diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/Kconfig | 14 | ||||
| -rw-r--r-- | block/Kconfig.iosched | 69 | ||||
| -rw-r--r-- | block/Makefile | 10 | ||||
| -rw-r--r-- | block/as-iosched.c | 2005 | ||||
| -rw-r--r-- | block/cfq-iosched.c | 2428 | ||||
| -rw-r--r-- | block/deadline-iosched.c | 878 | ||||
| -rw-r--r-- | block/elevator.c | 802 | ||||
| -rw-r--r-- | block/genhd.c | 726 | ||||
| -rw-r--r-- | block/ioctl.c | 275 | ||||
| -rw-r--r-- | block/ll_rw_blk.c | 3612 | ||||
| -rw-r--r-- | block/noop-iosched.c | 46 | ||||
| -rw-r--r-- | block/scsi_ioctl.c | 589 |
12 files changed, 11454 insertions, 0 deletions
diff --git a/block/Kconfig b/block/Kconfig new file mode 100644 index 00000000000..eb48edb80c1 --- /dev/null +++ b/block/Kconfig @@ -0,0 +1,14 @@ +# +# Block layer core configuration +# +#XXX - it makes sense to enable this only for 32-bit subarch's, not for x86_64 +#for instance. +config LBD + bool "Support for Large Block Devices" + depends on X86 || (MIPS && 32BIT) || PPC32 || ARCH_S390_31 || SUPERH || UML + help + Say Y here if you want to attach large (bigger than 2TB) discs to + your machine, or if you want to have a raid or loopback device + bigger than 2TB. Otherwise say N. + +source block/Kconfig.iosched diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched new file mode 100644 index 00000000000..f3b7753aac9 --- /dev/null +++ b/block/Kconfig.iosched @@ -0,0 +1,69 @@ + +menu "IO Schedulers" + +config IOSCHED_NOOP + bool + default y + ---help--- + The no-op I/O scheduler is a minimal scheduler that does basic merging + and sorting. Its main uses include non-disk based block devices like + memory devices, and specialised software or hardware environments + that do their own scheduling and require only minimal assistance from + the kernel. + +config IOSCHED_AS + tristate "Anticipatory I/O scheduler" + default y + ---help--- + The anticipatory I/O scheduler is the default disk scheduler. It is + generally a good choice for most environments, but is quite large and + complex when compared to the deadline I/O scheduler, it can also be + slower in some cases especially some database loads. + +config IOSCHED_DEADLINE + tristate "Deadline I/O scheduler" + default y + ---help--- + The deadline I/O scheduler is simple and compact, and is often as + good as the anticipatory I/O scheduler, and in some database + workloads, better. In the case of a single process performing I/O to + a disk at any one time, its behaviour is almost identical to the + anticipatory I/O scheduler and so is a good choice. + +config IOSCHED_CFQ + tristate "CFQ I/O scheduler" + default y + ---help--- + The CFQ I/O scheduler tries to distribute bandwidth equally + among all processes in the system. It should provide a fair + working environment, suitable for desktop systems. + +choice + prompt "Default I/O scheduler" + default DEFAULT_AS + help + Select the I/O scheduler which will be used by default for all + block devices. + + config DEFAULT_AS + bool "Anticipatory" if IOSCHED_AS=y + + config DEFAULT_DEADLINE + bool "Deadline" if IOSCHED_DEADLINE=y + + config DEFAULT_CFQ + bool "CFQ" if IOSCHED_CFQ=y + + config DEFAULT_NOOP + bool "No-op" + +endchoice + +config DEFAULT_IOSCHED + string + default "anticipatory" if DEFAULT_AS + default "deadline" if DEFAULT_DEADLINE + default "cfq" if DEFAULT_CFQ + default "noop" if DEFAULT_NOOP + +endmenu diff --git a/block/Makefile b/block/Makefile new file mode 100644 index 00000000000..7e4f93e2b44 --- /dev/null +++ b/block/Makefile @@ -0,0 +1,10 @@ +# +# Makefile for the kernel block layer +# + +obj-y := elevator.o ll_rw_blk.o ioctl.o genhd.o scsi_ioctl.o + +obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o +obj-$(CONFIG_IOSCHED_AS) += as-iosched.o +obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o +obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o diff --git a/block/as-iosched.c b/block/as-iosched.c new file mode 100644 index 00000000000..a78e160b59a --- /dev/null +++ b/block/as-iosched.c @@ -0,0 +1,2005 @@ +/* + * linux/drivers/block/as-iosched.c + * + * Anticipatory & deadline i/o scheduler. + * + * Copyright (C) 2002 Jens Axboe <axboe@suse.de> + * Nick Piggin <nickpiggin@yahoo.com.au> + * + */ +#include <linux/kernel.h> +#include <linux/fs.h> +#include <linux/blkdev.h> +#include <linux/elevator.h> +#include <linux/bio.h> +#include <linux/config.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/compiler.h> +#include <linux/hash.h> +#include <linux/rbtree.h> +#include <linux/interrupt.h> + +#define REQ_SYNC 1 +#define REQ_ASYNC 0 + +/* + * See Documentation/block/as-iosched.txt + */ + +/* + * max time before a read is submitted. + */ +#define default_read_expire (HZ / 8) + +/* + * ditto for writes, these limits are not hard, even + * if the disk is capable of satisfying them. + */ +#define default_write_expire (HZ / 4) + +/* + * read_batch_expire describes how long we will allow a stream of reads to + * persist before looking to see whether it is time to switch over to writes. + */ +#define default_read_batch_expire (HZ / 2) + +/* + * write_batch_expire describes how long we want a stream of writes to run for. + * This is not a hard limit, but a target we set for the auto-tuning thingy. + * See, the problem is: we can send a lot of writes to disk cache / TCQ in + * a short amount of time... + */ +#define default_write_batch_expire (HZ / 8) + +/* + * max time we may wait to anticipate a read (default around 6ms) + */ +#define default_antic_expire ((HZ / 150) ? HZ / 150 : 1) + +/* + * Keep track of up to 20ms thinktimes. We can go as big as we like here, + * however huge values tend to interfere and not decay fast enough. A program + * might be in a non-io phase of operation. Waiting on user input for example, + * or doing a lengthy computation. A small penalty can be justified there, and + * will still catch out those processes that constantly have large thinktimes. + */ +#define MAX_THINKTIME (HZ/50UL) + +/* Bits in as_io_context.state */ +enum as_io_states { + AS_TASK_RUNNING=0, /* Process has not exited */ + AS_TASK_IOSTARTED, /* Process has started some IO */ + AS_TASK_IORUNNING, /* Process has completed some IO */ +}; + +enum anticipation_status { + ANTIC_OFF=0, /* Not anticipating (normal operation) */ + ANTIC_WAIT_REQ, /* The last read has not yet completed */ + ANTIC_WAIT_NEXT, /* Currently anticipating a request vs + last read (which has completed) */ + ANTIC_FINISHED, /* Anticipating but have found a candidate + * or timed out */ +}; + +struct as_data { + /* + * run time data + */ + + struct request_queue *q; /* the "owner" queue */ + + /* + * requests (as_rq s) are present on both sort_list and fifo_list + */ + struct rb_root sort_list[2]; + struct list_head fifo_list[2]; + + struct as_rq *next_arq[2]; /* next in sort order */ + sector_t last_sector[2]; /* last REQ_SYNC & REQ_ASYNC sectors */ + struct list_head *hash; /* request hash */ + + unsigned long exit_prob; /* probability a task will exit while + being waited on */ + unsigned long exit_no_coop; /* probablility an exited task will + not be part of a later cooperating + request */ + unsigned long new_ttime_total; /* mean thinktime on new proc */ + unsigned long new_ttime_mean; + u64 new_seek_total; /* mean seek on new proc */ + sector_t new_seek_mean; + + unsigned long current_batch_expires; + unsigned long last_check_fifo[2]; + int changed_batch; /* 1: waiting for old batch to end */ + int new_batch; /* 1: waiting on first read complete */ + int batch_data_dir; /* current batch REQ_SYNC / REQ_ASYNC */ + int write_batch_count; /* max # of reqs in a write batch */ + int current_write_count; /* how many requests left this batch */ + int write_batch_idled; /* has the write batch gone idle? */ + mempool_t *arq_pool; + + enum anticipation_status antic_status; + unsigned long antic_start; /* jiffies: when it started */ + struct timer_list antic_timer; /* anticipatory scheduling timer */ + struct work_struct antic_work; /* Deferred unplugging */ + struct io_context *io_context; /* Identify the expected process */ + int ioc_finished; /* IO associated with io_context is finished */ + int nr_dispatched; + + /* + * settings that change how the i/o scheduler behaves + */ + unsigned long fifo_expire[2]; + unsigned long batch_expire[2]; + unsigned long antic_expire; +}; + +#define list_entry_fifo(ptr) list_entry((ptr), struct as_rq, fifo) + +/* + * per-request data. + */ +enum arq_state { + AS_RQ_NEW=0, /* New - not referenced and not on any lists */ + AS_RQ_QUEUED, /* In the request queue. It belongs to the + scheduler */ + AS_RQ_DISPATCHED, /* On the dispatch list. It belongs to the + driver now */ + AS_RQ_PRESCHED, /* Debug poisoning for requests being used */ + AS_RQ_REMOVED, + AS_RQ_MERGED, + AS_RQ_POSTSCHED, /* when they shouldn't be */ +}; + +struct as_rq { + /* + * rbtree index, key is the starting offset + */ + struct rb_node rb_node; + sector_t rb_key; + + struct request *request; + + struct io_context *io_context; /* The submitting task */ + + /* + * request hash, key is the ending offset (for back merge lookup) + */ + struct list_head hash; + unsigned int on_hash; + + /* + * expire fifo + */ + struct list_head fifo; + unsigned long expires; + + unsigned int is_sync; + enum arq_state state; +}; + +#define RQ_DATA(rq) ((struct as_rq *) (rq)->elevator_private) + +static kmem_cache_t *arq_pool; + +/* + * IO Context helper functions + */ + +/* Called to deallocate the as_io_context */ +static void free_as_io_context(struct as_io_context *aic) +{ + kfree(aic); +} + +/* Called when the task exits */ +static void exit_as_io_context(struct as_io_context *aic) +{ + WARN_ON(!test_bit(AS_TASK_RUNNING, &aic->state)); + clear_bit(AS_TASK_RUNNING, &aic->state); +} + +static struct as_io_context *alloc_as_io_context(void) +{ + struct as_io_context *ret; + + ret = kmalloc(sizeof(*ret), GFP_ATOMIC); + if (ret) { + ret->dtor = free_as_io_context; + ret->exit = exit_as_io_context; + ret->state = 1 << AS_TASK_RUNNING; + atomic_set(&ret->nr_queued, 0); + atomic_set(&ret->nr_dispatched, 0); + spin_lock_init(&ret->lock); + ret->ttime_total = 0; + ret->ttime_samples = 0; + ret->ttime_mean = 0; + ret->seek_total = 0; + ret->seek_samples = 0; + ret->seek_mean = 0; + } + + return ret; +} + +/* + * If the current task has no AS IO context then create one and initialise it. + * Then take a ref on the task's io context and return it. + */ +static struct io_context *as_get_io_context(void) +{ + struct io_context *ioc = get_io_context(GFP_ATOMIC); + if (ioc && !ioc->aic) { + ioc->aic = alloc_as_io_context(); + if (!ioc->aic) { + put_io_context(ioc); + ioc = NULL; + } + } + return ioc; +} + +static void as_put_io_context(struct as_rq *arq) +{ + struct as_io_context *aic; + + if (unlikely(!arq->io_context)) + return; + + aic = arq->io_context->aic; + + if (arq->is_sync == REQ_SYNC && aic) { + spin_lock(&aic->lock); + set_bit(AS_TASK_IORUNNING, &aic->state); + aic->last_end_request = jiffies; + spin_unlock(&aic->lock); + } + + put_io_context(arq->io_context); +} + +/* + * the back merge hash support functions + */ +static const int as_hash_shift = 6; +#define AS_HASH_BLOCK(sec) ((sec) >> 3) +#define AS_HASH_FN(sec) (hash_long(AS_HASH_BLOCK((sec)), as_hash_shift)) +#define AS_HASH_ENTRIES (1 << as_hash_shift) +#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) +#define list_entry_hash(ptr) list_entry((ptr), struct as_rq, hash) + +static inline void __as_del_arq_hash(struct as_rq *arq) +{ + arq->on_hash = 0; + list_del_init(&arq->hash); +} + +static inline void as_del_arq_hash(struct as_rq *arq) +{ + if (arq->on_hash) + __as_del_arq_hash(arq); +} + +static void as_add_arq_hash(struct as_data *ad, struct as_rq *arq) +{ + struct request *rq = arq->request; + + BUG_ON(arq->on_hash); + + arq->on_hash = 1; + list_add(&arq->hash, &ad->hash[AS_HASH_FN(rq_hash_key(rq))]); +} + +/* + * move hot entry to front of chain + */ +static inline void as_hot_arq_hash(struct as_data *ad, struct as_rq *arq) +{ + struct request *rq = arq->request; + struct list_head *head = &ad->hash[AS_HASH_FN(rq_hash_key(rq))]; + + if (!arq->on_hash) { + WARN_ON(1); + return; + } + + if (arq->hash.prev != head) { + list_del(&arq->hash); + list_add(&arq->hash, head); + } +} + +static struct request *as_find_arq_hash(struct as_data *ad, sector_t offset) +{ + struct list_head *hash_list = &ad->hash[AS_HASH_FN(offset)]; + struct list_head *entry, *next = hash_list->next; + + while ((entry = next) != hash_list) { + struct as_rq *arq = list_entry_hash(entry); + struct request *__rq = arq->request; + + next = entry->next; + + BUG_ON(!arq->on_hash); + + if (!rq_mergeable(__rq)) { + as_del_arq_hash(arq); + continue; + } + + if (rq_hash_key(__rq) == offset) + return __rq; + } + + return NULL; +} + +/* + * rb tree support functions + */ +#define RB_NONE (2) +#define RB_EMPTY(root) ((root)->rb_node == NULL) +#define ON_RB(node) ((node)->rb_color != RB_NONE) +#define RB_CLEAR(node) ((node)->rb_color = RB_NONE) +#define rb_entry_arq(node) rb_entry((node), struct as_rq, rb_node) +#define ARQ_RB_ROOT(ad, arq) (&(ad)->sort_list[(arq)->is_sync]) +#define rq_rb_key(rq) (rq)->sector + +/* + * as_find_first_arq finds the first (lowest sector numbered) request + * for the specified data_dir. Used to sweep back to the start of the disk + * (1-way elevator) after we process the last (highest sector) request. + */ +static struct as_rq *as_find_first_arq(struct as_data *ad, int data_dir) +{ + struct rb_node *n = ad->sort_list[data_dir].rb_node; + + if (n == NULL) + return NULL; + + for (;;) { + if (n->rb_left == NULL) + return rb_entry_arq(n); + + n = n->rb_left; + } +} + +/* + * Add the request to the rb tree if it is unique. If there is an alias (an + * existing request against the same sector), which can happen when using + * direct IO, then return the alias. + */ +static struct as_rq *as_add_arq_rb(struct as_data *ad, struct as_rq *arq) +{ + struct rb_node **p = &ARQ_RB_ROOT(ad, arq)->rb_node; + struct rb_node *parent = NULL; + struct as_rq *__arq; + struct request *rq = arq->request; + + arq->rb_key = rq_rb_key(rq); + + while (*p) { + parent = *p; + __arq = rb_entry_arq(parent); + + if (arq->rb_key < __arq->rb_key) + p = &(*p)->rb_left; + else if (arq->rb_key > __arq->rb_key) + p = &(*p)->rb_right; + else + return __arq; + } + + rb_link_node(&arq->rb_node, parent, p); + rb_insert_color(&arq->rb_node, ARQ_RB_ROOT(ad, arq)); + + return NULL; +} + +static inline void as_del_arq_rb(struct as_data *ad, struct as_rq *arq) +{ + if (!ON_RB(&arq->rb_node)) { + WARN_ON(1); + return; + } + + rb_erase(&arq->rb_node, ARQ_RB_ROOT(ad, arq)); + RB_CLEAR(&arq->rb_node); +} + +static struct request * +as_find_arq_rb(struct as_data *ad, sector_t sector, int data_dir) +{ + struct rb_node *n = ad->sort_list[data_dir].rb_node; + struct as_rq *arq; + + while (n) { + arq = rb_entry_arq(n); + + if (sector < arq->rb_key) + n = n->rb_left; + else if (sector > arq->rb_key) + n = n->rb_right; + else + return arq->request; + } + + return NULL; +} + +/* + * IO Scheduler proper + */ + +#define MAXBACK (1024 * 1024) /* + * Maximum distance the disk will go backward + * for a request. + */ + +#define BACK_PENALTY 2 + +/* + * as_choose_req selects the preferred one of two requests of the same data_dir + * ignoring time - eg. timeouts, which is the job of as_dispatch_request + */ +static struct as_rq * +as_choose_req(struct as_data *ad, struct as_rq *arq1, struct as_rq *arq2) +{ + int data_dir; + sector_t last, s1, s2, d1, d2; + int r1_wrap=0, r2_wrap=0; /* requests are behind the disk head */ + const sector_t maxback = MAXBACK; + + if (arq1 == NULL || arq1 == arq2) + return arq2; + if (arq2 == NULL) + return arq1; + + data_dir = arq1->is_sync; + + last = ad->last_sector[data_dir]; + s1 = arq1->request->sector; + s2 = arq2->request->sector; + + BUG_ON(data_dir != arq2->is_sync); + + /* + * Strict one way elevator _except_ in the case where we allow + * short backward seeks which are biased as twice the cost of a + * similar forward seek. + */ + if (s1 >= last) + d1 = s1 - last; + else if (s1+maxback >= last) + d1 = (last - s1)*BACK_PENALTY; + else { + r1_wrap = 1; + d1 = 0; /* shut up, gcc */ + } + + if (s2 >= last) + d2 = s2 - last; + else if (s2+maxback >= last) + d2 = (last - s2)*BACK_PENALTY; + else { + r2_wrap = 1; + d2 = 0; + } + + /* Found required data */ + if (!r1_wrap && r2_wrap) + return arq1; + else if (!r2_wrap && r1_wrap) + return arq2; + else if (r1_wrap && r2_wrap) { + /* both behind the head */ + if (s1 <= s2) + return arq1; + else + return arq2; + } + + /* Both requests in front of the head */ + if (d1 < d2) + return arq1; + else if (d2 < d1) + return arq2; + else { + if (s1 >= s2) + return arq1; + else + return arq2; + } +} + +/* + * as_find_next_arq finds the next request after @prev in elevator order. + * this with as_choose_req form the basis for how the scheduler chooses + * what request to process next. Anticipation works on top of this. + */ +static struct as_rq *as_find_next_arq(struct as_data *ad, struct as_rq *last) +{ + const int data_dir = last->is_sync; + struct as_rq *ret; + struct rb_node *rbnext = rb_next(&last->rb_node); + struct rb_node *rbprev = rb_prev(&last->rb_node); + struct as_rq *arq_next, *arq_prev; + + BUG_ON(!ON_RB(&last->rb_node)); + + if (rbprev) + arq_prev = rb_entry_arq(rbprev); + else + arq_prev = NULL; + + if (rbnext) + arq_next = rb_entry_arq(rbnext); + else { + arq_next = as_find_first_arq(ad, data_dir); + if (arq_next == last) + arq_next = NULL; + } + + ret = as_choose_req(ad, arq_next, arq_prev); + + return ret; +} + +/* + * anticipatory scheduling functions follow + */ + +/* + * as_antic_expired tells us when we have anticipated too long. + * The funny "absolute difference" math on the elapsed time is to handle + * jiffy wraps, and disks which have been idle for 0x80000000 jiffies. + */ +static int as_antic_expired(struct as_data *ad) +{ + long delta_jif; + + delta_jif = jiffies - ad->antic_start; + if (unlikely(delta_jif < 0)) + delta_jif = -delta_jif; + if (delta_jif < ad->antic_expire) + return 0; + + return 1; +} + +/* + * as_antic_waitnext starts anticipating that a nice request will soon be + * submitted. See also as_antic_waitreq + */ +static void as_antic_waitnext(struct as_data *ad) +{ + unsigned long timeout; + + BUG_ON(ad->antic_status != ANTIC_OFF + && ad->antic_status != ANTIC_WAIT_REQ); + + timeout = ad->antic_start + ad->antic_expire; + + mod_timer(&ad->antic_timer, timeout); + + ad->antic_status = ANTIC_WAIT_NEXT; +} + +/* + * as_antic_waitreq starts anticipating. We don't start timing the anticipation + * until the request that we're anticipating on has finished. This means we + * are timing from when the candidate process wakes up hopefully. + */ +static void as_antic_waitreq(struct as_data *ad) +{ + BUG_ON(ad->antic_status == ANTIC_FINISHED); + if (ad->antic_status == ANTIC_OFF) { + if (!ad->io_context || ad->ioc_finished) + as_antic_waitnext(ad); + else + ad->antic_status = ANTIC_WAIT_REQ; + } +} + +/* + * This is called directly by the functions in this file to stop anticipation. + * We kill the timer and schedule a call to the request_fn asap. + */ +static void as_antic_stop(struct as_data *ad) +{ + int status = ad->antic_status; + + if (status == ANTIC_WAIT_REQ || status == ANTIC_WAIT_NEXT) { + if (status == ANTIC_WAIT_NEXT) + del_timer(&ad->antic_timer); + ad->antic_status = ANTIC_FINISHED; + /* see as_work_handler */ + kblockd_schedule_work(&ad->antic_work); + } +} + +/* + * as_antic_timeout is the timer function set by as_antic_waitnext. + */ +static void as_antic_timeout(unsigned long data) +{ + struct request_queue *q = (struct request_queue *)data; + struct as_data *ad = q->elevator->elevator_data; + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + if (ad->antic_status == ANTIC_WAIT_REQ + || ad->antic_status == ANTIC_WAIT_NEXT) { + struct as_io_context *aic = ad->io_context->aic; + + ad->antic_status = ANTIC_FINISHED; + kblockd_schedule_work(&ad->antic_work); + + if (aic->ttime_samples == 0) { + /* process anticipated on has exited or timed out*/ + ad->exit_prob = (7*ad->exit_prob + 256)/8; + } + if (!test_bit(AS_TASK_RUNNING, &aic->state)) { + /* process not "saved" by a cooperating request */ + ad->exit_no_coop = (7*ad->exit_no_coop + 256)/8; + } + } + spin_unlock_irqrestore(q->queue_lock, flags); +} + +static void as_update_thinktime(struct as_data *ad, struct as_io_context *aic, + unsigned long ttime) +{ + /* fixed point: 1.0 == 1<<8 */ + if (aic->ttime_samples == 0) { + ad->new_ttime_total = (7*ad->new_ttime_total + 256*ttime) / 8; + ad->new_ttime_mean = ad->new_ttime_total / 256; + + ad->exit_prob = (7*ad->exit_prob)/8; + } + aic->ttime_samples = (7*aic->ttime_samples + 256) / 8; + aic->ttime_total = (7*aic->ttime_total + 256*ttime) / 8; + aic->ttime_mean = (aic->ttime_total + 128) / aic->ttime_samples; +} + +static void as_update_seekdist(struct as_data *ad, struct as_io_context *aic, + sector_t sdist) +{ + u64 total; + + if (aic->seek_samples == 0) { + ad->new_seek_total = (7*ad->new_seek_total + 256*(u64)sdist)/8; + ad->new_seek_mean = ad->new_seek_total / 256; + } + + /* + * Don't allow the seek distance to get too large from the + * odd fragment, pagein, etc + */ + if (aic->seek_samples <= 60) /* second&third seek */ + sdist = min(sdist, (aic->seek_mean * 4) + 2*1024*1024); + else + sdist = min(sdist, (aic->seek_mean * 4) + 2*1024*64); + + aic->seek_samples = (7*aic->seek_samples + 256) / 8; + aic->seek_total = (7*aic->seek_total + (u64)256*sdist) / 8; + total = aic->seek_total + (aic->seek_samples/2); + do_div(total, aic->seek_samples); + aic->seek_mean = (sector_t)total; +} + +/* + * as_update_iohist keeps a decaying histogram of IO thinktimes, and + * updates @aic->ttime_mean based on that. It is called when a new + * request is queued. + */ +static void as_update_iohist(struct as_data *ad, struct as_io_context *aic, + struct request *rq) +{ + struct as_rq *arq = RQ_DATA(rq); + int data_dir = arq->is_sync; + unsigned long thinktime = 0; + sector_t seek_dist; + + if (aic == NULL) + return; + + if (data_dir == REQ_SYNC) { + unsigned long in_flight = atomic_read(&aic->nr_queued) + + atomic_read(&aic->nr_dispatched); + spin_lock(&aic->lock); + if (test_bit(AS_TASK_IORUNNING, &aic->state) || + test_bit(AS_TASK_IOSTARTED, &aic->state)) { + /* Calculate read -> read thinktime */ + if (test_bit(AS_TASK_IORUNNING, &aic->state) + && in_flight == 0) { + thinktime = jiffies - aic->last_end_request; + thinktime = min(thinktime, MAX_THINKTIME-1); + } + as_update_thinktime(ad, aic, thinktime); + + /* Calculate read -> read seek distance */ + if (aic->last_request_pos < rq->sector) + seek_dist = rq->sector - aic->last_request_pos; + else + seek_dist = aic->last_request_pos - rq->sector; + as_update_seekdist(ad, aic, seek_dist); + } + aic->last_request_pos = rq->sector + rq->nr_sectors; + set_bit(AS_TASK_IOSTARTED, &aic->state); + spin_unlock(&aic->lock); + } +} + +/* + * as_close_req decides if one request is considered "close" to the + * previous one issued. + */ +static int as_close_req(struct as_data *ad, struct as_io_context *aic, + struct as_rq *arq) +{ + unsigned long delay; /* milliseconds */ + sector_t last = ad->last_sector[ad->batch_data_dir]; + sector_t next = arq->request->sector; + sector_t delta; /* acceptable close offset (in sectors) */ + sector_t s; + + if (ad->antic_status == ANTIC_OFF || !ad->ioc_finished) + delay = 0; + else + delay = ((jiffies - ad->antic_start) * 1000) / HZ; + + if (delay == 0) + delta = 8192; + else if (delay <= 20 && delay <= ad->antic_expire) + delta = 8192 << delay; + else + return 1; + + if ((last <= next + (delta>>1)) && (next <= last + delta)) + return 1; + + if (last < next) + s = next - last; + else + s = last - next; + + if (aic->seek_samples == 0) { + /* + * Process has just started IO. Use past statistics to + * gauge success possibility + */ + if (ad->new_seek_mean > s) { + /* this request is better than what we're expecting */ + return 1; + } + + } else { + if (aic->seek_mean > s) { + /* this request is better than what we're expecting */ + return 1; + } + } + + return 0; +} + +/* + * as_can_break_anticipation returns true if we have been anticipating this + * request. + * + * It also returns true if the process against which we are anticipating + * submits a write - that's presumably an fsync, O_SYNC write, etc. We want to + * dispatch it ASAP, because we know that application will not be submitting + * any new reads. + * + * If the task which has submitted the request has exited, break anticipation. + * + * If this task has queued some other IO, do not enter enticipation. + */ +static int as_can_break_anticipation(struct as_data *ad, struct as_rq *arq) +{ + struct io_context *ioc; + struct as_io_context *aic; + + ioc = ad->io_context; + BUG_ON(!ioc); + + if (arq && ioc == arq->io_context) { + /* request from same process */ + return 1; + } + + if (ad->ioc_finished && as_antic_expired(ad)) { + /* + * In this situation status should really be FINISHED, + * however the timer hasn't had the chance to run yet. + */ + return 1; + } + + aic = ioc->aic; + if (!aic) + return 0; + + if (atomic_read(&aic->nr_queued) > 0) { + /* process has more requests queued */ + return 1; + } + + if (atomic_read(&aic->nr_dispatched) > 0) { + /* process has more requests dispatched */ + return 1; + } + + if (arq && arq->is_sync == REQ_SYNC && as_close_req(ad, aic, arq)) { + /* + * Found a close request that is not one of ours. + * + * This makes close requests from another process update + * our IO history. Is generally useful when there are + * two or more cooperating processes working in the same + * area. + */ + if (!test_bit(AS_TASK_RUNNING, &aic->state)) { + if (aic->ttime_samples == 0) + ad->exit_prob = (7*ad->exit_prob + 256)/8; + + ad->exit_no_coop = (7*ad->exit_no_coop)/8; + } + + as_update_iohist(ad, aic, arq->request); + return 1; + } + + if (!test_bit(AS_TASK_RUNNING, &aic->state)) { + /* process anticipated on has exited */ + if (aic->ttime_samples == 0) + ad->exit_prob = (7*ad->exit_prob + 256)/8; + + if (ad->exit_no_coop > 128) + return 1; + } + + if (aic->ttime_samples == 0) { + if (ad->new_ttime_mean > ad->antic_expire) + return 1; + if (ad->exit_prob * ad->exit_no_coop > 128*256) + return 1; + } else if (aic->ttime_mean > ad->antic_expire) { + /* the process thinks too much between requests */ + return 1; + } + + return 0; +} + +/* + * as_can_anticipate indicates weather we should either run arq + * or keep anticipating a better request. + */ +static int as_can_anticipate(struct as_data *ad, struct as_rq *arq) +{ + if (!ad->io_context) + /* + * Last request submitted was a write + */ + return 0; + + if (ad->antic_status == ANTIC_FINISHED) + /* + * Don't restart if we have just finished. Run the next request + */ + return 0; + + if (as_can_break_anticipation(ad, arq)) + /* + * This request is a good candidate. Don't keep anticipating, + * run it. + */ + return 0; + + /* + * OK from here, we haven't finished, and don't have a decent request! + * Status is either ANTIC_OFF so start waiting, + * ANTIC_WAIT_REQ so continue waiting for request to finish + * or ANTIC_WAIT_NEXT so continue waiting for an acceptable request. + */ + + return 1; +} + +/* + * as_update_arq must be called whenever a request (arq) is added to + * the sort_list. This function keeps caches up to date, and checks if the + * request might be one we are "anticipating" + */ +static void as_update_arq(struct as_data *ad, struct as_rq *arq) +{ + const int data_dir = arq->is_sync; + + /* keep the next_arq cache up to date */ + ad->next_arq[data_dir] = as_choose_req(ad, arq, ad->next_arq[data_dir]); + + /* + * have we been anticipating this request? + * or does it come from the same process as the one we are anticipating + * for? + */ + if (ad->antic_status == ANTIC_WAIT_REQ + || ad->antic_status == ANTIC_WAIT_NEXT) { + if (as_can_break_anticipation(ad, arq)) + as_antic_stop(ad); + } +} + +/* + * Gathers timings and resizes the write batch automatically + */ +static void update_write_batch(struct as_data *ad) +{ + unsigned long batch = ad->batch_expire[REQ_ASYNC]; + long write_time; + + write_time = (jiffies - ad->current_batch_expires) + batch; + if (write_time < 0) + write_time = 0; + + if (write_time > batch && !ad->write_batch_idled) { + if (write_time > batch * 3) + ad->write_batch_count /= 2; + else + ad->write_batch_count--; + } else if (write_time < batch && ad->current_write_count == 0) { + if (batch > write_time * 3) + ad->write_batch_count *= 2; + else + ad->write_batch_count++; + } + + if (ad->write_batch_count < 1) + ad->write_batch_count = 1; +} + +/* + * as_completed_request is to be called when a request has completed and + * returned something to the requesting process, be it an error or data. + */ +static void as_completed_request(request_queue_t *q, struct request *rq) +{ + struct as_data *ad = q->elevator->elevator_data; + struct as_rq *arq = RQ_DATA(rq); + + WARN_ON(!list_empty(&rq->queuelist)); + + if (arq->state != AS_RQ_REMOVED) { + printk("arq->state %d\n", arq->state); + WARN_ON(1); + goto out; + } + + if (ad->changed_batch && ad->nr_dispatched == 1) { + kblockd_schedule_work(&ad->antic_work); + ad->changed_batch = 0; + + if (ad->batch_data_dir == REQ_SYNC) + ad->new_batch = 1; + } + WARN_ON(ad->nr_dispatched == 0); + ad->nr_dispatched--; + + /* + * Start counting the batch from when a request of that direction is + * actually serviced. This should help devices with big TCQ windows + * and writeback caches + */ + if (ad->new_batch && ad->batch_data_dir == arq->is_sync) { + update_write_batch(ad); + ad->current_batch_expires = jiffies + + ad->batch_expire[REQ_SYNC]; + ad->new_batch = 0; + } + + if (ad->io_context == arq->io_context && ad->io_context) { + ad->antic_start = jiffies; + ad->ioc_finished = 1; + if (ad->antic_status == ANTIC_WAIT_REQ) { + /* + * We were waiting on this request, now anticipate + * the next one + */ + as_antic_waitnext(ad); + } + } + + as_put_io_context(arq); +out: + arq->state = AS_RQ_POSTSCHED; +} + +/* + * as_remove_queued_request removes a request from the pre dispatch queue + * without updating refcounts. It is expected the caller will drop the + * reference unless it replaces the request at somepart of the elevator + * (ie. the dispatch queue) + */ +static void as_remove_queued_request(request_queue_t *q, struct request *rq) +{ + struct as_rq *arq = RQ_DATA(rq); + const int data_dir = arq->is_sync; + struct as_data *ad = q->elevator->elevator_data; + + WARN_ON(arq->state != AS_RQ_QUEUED); + + if (arq->io_context && arq->io_context->aic) { + BUG_ON(!atomic_read(&arq->io_context->aic->nr_queued)); + atomic_dec(&arq->io_context->aic->nr_queued); + } + + /* + * Update the "next_arq" cache if we are about to remove its + * entry + */ + if (ad->next_arq[data_dir] == arq) + ad->next_arq[data_dir] = as_find_next_arq(ad, arq); + + list_del_init(&arq->fifo); + as_del_arq_hash(arq); + as_del_arq_rb(ad, arq); +} + +/* + * as_fifo_expired returns 0 if there are no expired reads on the fifo, + * 1 otherwise. It is ratelimited so that we only perform the check once per + * `fifo_expire' interval. Otherwise a large number of expired requests + * would create a hopeless seekstorm. + * + * See as_antic_expired comment. + */ +static int as_fifo_expired(struct as_data *ad, int adir) +{ + struct as_rq *arq; + long delta_jif; + + delta_jif = jiffies - ad->last_check_fifo[adir]; + if (unlikely(delta_jif < 0)) + delta_jif = -delta_jif; + if (delta_jif < ad->fifo_expire[adir]) + return 0; + + ad->last_check_fifo[adir] = jiffies; + + if (list_empty(&ad->fifo_list[adir])) + return 0; + + arq = list_entry_fifo(ad->fifo_list[adir].next); + + return time_after(jiffies, arq->expires); +} + +/* + * as_batch_expired returns true if the current batch has expired. A batch + * is a set of reads or a set of writes. + */ +static inline int as_batch_expired(struct as_data *ad) +{ + if (ad->changed_batch || ad->new_batch) + return 0; + + if (ad->batch_data_dir == REQ_SYNC) + /* TODO! add a check so a complete fifo gets written? */ + return time_after(jiffies, ad->current_batch_expires); + + return time_after(jiffies, ad->current_batch_expires) + || ad->current_write_count == 0; +} + +/* + * move an entry to dispatch queue + */ +static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq) +{ + struct request *rq = arq->request; + const int data_dir = arq->is_sync; + + BUG_ON(!ON_RB(&arq->rb_node)); + + as_antic_stop(ad); + ad->antic_status = ANTIC_OFF; + + /* + * This has to be set in order to be correctly updated by + * as_find_next_arq + */ + ad->last_sector[data_dir] = rq->sector + rq->nr_sectors; + + if (data_dir == REQ_SYNC) { + /* In case we have to anticipate after this */ + copy_io_context(&ad->io_context, &arq->io_context); + } else { + if (ad->io_context) { + put_io_context(ad->io_context); + ad->io_context = NULL; + } + + if (ad->current_write_count != 0) + ad->current_write_count--; + } + ad->ioc_finished = 0; + + ad->next_arq[data_dir] = as_find_next_arq(ad, arq); + + /* + * take it off the sort and fifo list, add to dispatch queue + */ + while (!list_empty(&rq->queuelist)) { + struct request *__rq = list_entry_rq(rq->queuelist.next); + struct as_rq *__arq = RQ_DATA(__rq); + + list_del(&__rq->queuelist); + + elv_dispatch_add_tail(ad->q, __rq); + + if (__arq->io_context && __arq->io_context->aic) + atomic_inc(&__arq->io_context->aic->nr_dispatched); + + WARN_ON(__arq->state != AS_RQ_QUEUED); + __arq->state = AS_RQ_DISPATCHED; + + ad->nr_dispatched++; + } + + as_remove_queued_request(ad->q, rq); + WARN_ON(arq->state != AS_RQ_QUEUED); + + elv_dispatch_sort(ad->q, rq); + + arq->state = AS_RQ_DISPATCHED; + if (arq->io_context && arq->io_context->aic) + atomic_inc(&arq->io_context->aic->nr_dispatched); + ad->nr_dispatched++; +} + +/* + * as_dispatch_request selects the best request according to + * read/write expire, batch expire, etc, and moves it to the dispatch + * queue. Returns 1 if a request was found, 0 otherwise. + */ +static int as_dispatch_request(request_queue_t *q, int force) +{ + struct as_data *ad = q->elevator->elevator_data; + struct as_rq *arq; + const int reads = !list_empty(&ad->fifo_list[REQ_SYNC]); + const int writes = !list_empty(&ad->fifo_list[REQ_ASYNC]); + + if (unlikely(force)) { + /* + * Forced dispatch, accounting is useless. Reset + * accounting states and dump fifo_lists. Note that + * batch_data_dir is reset to REQ_SYNC to avoid + * screwing write batch accounting as write batch + * accounting occurs on W->R transition. + */ + int dispatched = 0; + + ad->batch_data_dir = REQ_SYNC; + ad->changed_batch = 0; + ad->new_batch = 0; + + while (ad->next_arq[REQ_SYNC]) { + as_move_to_dispatch(ad, ad->next_arq[REQ_SYNC]); + dispatched++; + } + ad->last_check_fifo[REQ_SYNC] = jiffies; + + while (ad->next_arq[REQ_ASYNC]) { + as_move_to_dispatch(ad, ad->next_arq[REQ_ASYNC]); + dispatched++; + } + ad->last_check_fifo[REQ_ASYNC] = jiffies; + + return dispatched; + } + + /* Signal that the write batch was uncontended, so we can't time it */ + if (ad->batch_data_dir == REQ_ASYNC && !reads) { + if (ad->current_write_count == 0 || !writes) + ad->write_batch_idled = 1; + } + + if (!(reads || writes) + || ad->antic_status == ANTIC_WAIT_REQ + || ad->antic_status == ANTIC_WAIT_NEXT + || ad->changed_batch) + return 0; + + if (!(reads && writes && as_batch_expired(ad))) { + /* + * batch is still running or no reads or no writes + */ + arq = ad->next_arq[ad->batch_data_dir]; + + if (ad->batch_data_dir == REQ_SYNC && ad->antic_expire) { + if (as_fifo_expired(ad, REQ_SYNC)) + goto fifo_expired; + + if (as_can_anticipate(ad, arq)) { + as_antic_waitreq(ad); + return 0; + } + } + + if (arq) { + /* we have a "next request" */ + if (reads && !writes) + ad->current_batch_expires = + jiffies + ad->batch_expire[REQ_SYNC]; + goto dispatch_request; + } + } + + /* + * at this point we are not running a batch. select the appropriate + * data direction (read / write) + */ + + if (reads) { + BUG_ON(RB_EMPTY(&ad->sort_list[REQ_SYNC])); + + if (writes && ad->batch_data_dir == REQ_SYNC) + /* + * Last batch was a read, switch to writes + */ + goto dispatch_writes; + + if (ad->batch_data_dir == REQ_ASYNC) { + WARN_ON(ad->new_batch); + ad->changed_batch = 1; + } + ad->batch_data_dir = REQ_SYNC; + arq = list_entry_fifo(ad->fifo_list[ad->batch_data_dir].next); + ad->last_check_fifo[ad->batch_data_dir] = jiffies; + goto dispatch_request; + } + + /* + * the last batch was a read + */ + + if (writes) { +dispatch_writes: + BUG_ON(RB_EMPTY(&ad->sort_list[REQ_ASYNC])); + + if (ad->batch_data_dir == REQ_SYNC) { + ad->changed_batch = 1; + + /* + * new_batch might be 1 when the queue runs out of + * reads. A subsequent submission of a write might + * cause a change of batch before the read is finished. + */ + ad->new_batch = 0; + } + ad->batch_data_dir = REQ_ASYNC; + ad->current_write_count = ad->write_batch_count; + ad->write_batch_idled = 0; + arq = ad->next_arq[ad->batch_data_dir]; + goto dispatch_request; + } + + BUG(); + return 0; + +dispatch_request: + /* + * If a request has expired, service it. + */ + + if (as_fifo_expired(ad, ad->batch_data_dir)) { +fifo_expired: + arq = list_entry_fifo(ad->fifo_list[ad->batch_data_dir].next); + BUG_ON(arq == NULL); + } + + if (ad->changed_batch) { + WARN_ON(ad->new_batch); + + if (ad->nr_dispatched) + return 0; + + if (ad->batch_data_dir == REQ_ASYNC) + ad->current_batch_expires = jiffies + + ad->batch_expire[REQ_ASYNC]; + else + ad->new_batch = 1; + + ad->changed_batch = 0; + } + + /* + * arq is the selected appropriate request. + */ + as_move_to_dispatch(ad, arq); + + return 1; +} + +/* + * Add arq to a list behind alias + */ +static inline void +as_add_aliased_request(struct as_data *ad, struct as_rq *arq, + struct as_rq *alias) +{ + struct request *req = arq->request; + struct list_head *insert = alias->request->queuelist.prev; + + /* + * Transfer list of aliases + */ + while (!list_empty(&req->queuelist)) { + struct request *__rq = list_entry_rq(req->queuelist.next); + struct as_rq *__arq = RQ_DATA(__rq); + + list_move_tail(&__rq->queuelist, &alias->request->queuelist); + + WARN_ON(__arq->state != AS_RQ_QUEUED); + } + + /* + * Another request with the same start sector on the rbtree. + * Link this request to that sector. They are untangled in + * as_move_to_dispatch + */ + list_add(&arq->request->queuelist, insert); + + /* + * Don't want to have to handle merges. + */ + as_del_arq_hash(arq); + arq->request->flags |= REQ_NOMERGE; +} + +/* + * add arq to rbtree and fifo + */ +static void as_add_request(request_queue_t *q, struct request *rq) +{ + struct as_data *ad = q->elevator->elevator_data; + struct as_rq *arq = RQ_DATA(rq); + struct as_rq *alias; + int data_dir; + + if (arq->state != AS_RQ_PRESCHED) { + printk("arq->state: %d\n", arq->state); + WARN_ON(1); + } + arq->state = AS_RQ_NEW; + + if (rq_data_dir(arq->request) == READ + || current->flags&PF_SYNCWRITE) + arq->is_sync = 1; + else + arq->is_sync = 0; + data_dir = arq->is_sync; + + arq->io_context = as_get_io_context(); + + if (arq->io_context) { + as_update_iohist(ad, arq->io_context->aic, arq->request); + atomic_inc(&arq->io_context->aic->nr_queued); + } + + alias = as_add_arq_rb(ad, arq); + if (!alias) { + /* + * set expire time (only used for reads) and add to fifo list + */ + arq->expires = jiffies + ad->fifo_expire[data_dir]; + list_add_tail(&arq->fifo, &ad->fifo_list[data_dir]); + + if (rq_mergeable(arq->request)) + as_add_arq_hash(ad, arq); + as_update_arq(ad, arq); /* keep state machine up to date */ + + } else { + as_add_aliased_request(ad, arq, alias); + + /* + * have we been anticipating this request? + * or does it come from the same process as the one we are + * anticipating for? + */ + if (ad->antic_status == ANTIC_WAIT_REQ + || ad->antic_status == ANTIC_WAIT_NEXT) { + if (as_can_break_anticipation(ad, arq)) + as_antic_stop(ad); + } + } + + arq->state = AS_RQ_QUEUED; +} + +static void as_activate_request(request_queue_t *q, struct request *rq) +{ + struct as_rq *arq = RQ_DATA(rq); + + WARN_ON(arq->state != AS_RQ_DISPATCHED); + arq->state = AS_RQ_REMOVED; + if (arq->io_context && arq->io_context->aic) + atomic_dec(&arq->io_context->aic->nr_dispatched); +} + +static void as_deactivate_request(request_queue_t *q, struct request *rq) +{ + struct as_rq *arq = RQ_DATA(rq); + + WARN_ON(arq->state != AS_RQ_REMOVED); + arq->state = AS_RQ_DISPATCHED; + if (arq->io_context && arq->io_context->aic) + atomic_inc(&arq->io_context->aic->nr_dispatched); +} + +/* + * as_queue_empty tells us if there are requests left in the device. It may + * not be the case that a driver can get the next request even if the queue + * is not empty - it is used in the block layer to check for plugging and + * merging opportunities + */ +static int as_queue_empty(request_queue_t *q) +{ + struct as_data *ad = q->elevator->elevator_data; + + return list_empty(&ad->fifo_list[REQ_ASYNC]) + && list_empty(&ad->fifo_list[REQ_SYNC]); +} + +static struct request *as_former_request(request_queue_t *q, + struct request *rq) +{ + struct as_rq *arq = RQ_DATA(rq); + struct rb_node *rbprev = rb_prev(&arq->rb_node); + struct request *ret = NULL; + + if (rbprev) + ret = rb_entry_arq(rbprev)->request; + + return ret; +} + +static struct request *as_latter_request(request_queue_t *q, + struct request *rq) +{ + struct as_rq *arq = RQ_DATA(rq); + struct rb_node *rbnext = rb_next(&arq->rb_node); + struct request *ret = NULL; + + if (rbnext) + ret = rb_entry_arq(rbnext)->request; + + return ret; +} + +static int +as_merge(request_queue_t *q, struct request **req, struct bio *bio) +{ + struct as_data *ad = q->elevator->elevator_data; + sector_t rb_key = bio->bi_sector + bio_sectors(bio); + struct request *__rq; + int ret; + + /* + * see if the merge hash can satisfy a back merge + */ + __rq = as_find_arq_hash(ad, bio->bi_sector); + if (__rq) { + BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector); + + if (elv_rq_merge_ok(__rq, bio)) { + ret = ELEVATOR_BACK_MERGE; + goto out; + } + } + + /* + * check for front merge + */ + __rq = as_find_arq_rb(ad, rb_key, bio_data_dir(bio)); + if (__rq) { + BUG_ON(rb_key != rq_rb_key(__rq)); + + if (elv_rq_merge_ok(__rq, bio)) { + ret = ELEVATOR_FRONT_MERGE; + goto out; + } + } + + return ELEVATOR_NO_MERGE; +out: + if (ret) { + if (rq_mergeable(__rq)) + as_hot_arq_hash(ad, RQ_DATA(__rq)); + } + *req = __rq; + return ret; +} + +static void as_merged_request(request_queue_t *q, struct request *req) +{ + struct as_data *ad = q->elevator->elevator_data; + struct as_rq *arq = RQ_DATA(req); + + /* + * hash always needs to be repositioned, key is end sector + */ + as_del_arq_hash(arq); + as_add_arq_hash(ad, arq); + + /* + * if the merge was a front merge, we need to reposition request + */ + if (rq_rb_key(req) != arq->rb_key) { + struct as_rq *alias, *next_arq = NULL; + + if (ad->next_arq[arq->is_sync] == arq) + next_arq = as_find_next_arq(ad, arq); + + /* + * Note! We should really be moving any old aliased requests + * off this request and try to insert them into the rbtree. We + * currently don't bother. Ditto the next function. + */ + as_del_arq_rb(ad, arq); + if ((alias = as_add_arq_rb(ad, arq))) { + list_del_init(&arq->fifo); + as_add_aliased_request(ad, arq, alias); + if (next_arq) + ad->next_arq[arq->is_sync] = next_arq; + } + /* + * Note! At this stage of this and the next function, our next + * request may not be optimal - eg the request may have "grown" + * behind the disk head. We currently don't bother adjusting. + */ + } +} + +static void as_merged_requests(request_queue_t *q, struct request *req, + struct request *next) +{ + struct as_data *ad = q->elevator->elevator_data; + struct as_rq *arq = RQ_DATA(req); + struct as_rq *anext = RQ_DATA(next); + + BUG_ON(!arq); + BUG_ON(!anext); + + /* + * reposition arq (this is the merged request) in hash, and in rbtree + * in case of a front merge + */ + as_del_arq_hash(arq); + as_add_arq_hash(ad, arq); + + if (rq_rb_key(req) != arq->rb_key) { + struct as_rq *alias, *next_arq = NULL; + + if (ad->next_arq[arq->is_sync] == arq) + next_arq = as_find_next_arq(ad, arq); + + as_del_arq_rb(ad, arq); + if ((alias = as_add_arq_rb(ad, arq))) { + list_del_init(&arq->fifo); + as_add_aliased_request(ad, arq, alias); + if (next_arq) + ad->next_arq[arq->is_sync] = next_arq; + } + } + + /* + * if anext expires before arq, assign its expire time to arq + * and move into anext position (anext will be deleted) in fifo + */ + if (!list_empty(&arq->fifo) && !list_empty(&anext->fifo)) { + if (time_before(anext->expires, arq->expires)) { + list_move(&arq->fifo, &anext->fifo); + arq->expires = anext->expires; + /* + * Don't copy here but swap, because when anext is + * removed below, it must contain the unused context + */ + swap_io_context(&arq->io_context, &anext->io_context); + } + } + + /* + * Transfer list of aliases + */ + while (!list_empty(&next->queuelist)) { + struct request *__rq = list_entry_rq(next->queuelist.next); + struct as_rq *__arq = RQ_DATA(__rq); + + list_move_tail(&__rq->queuelist, &req->queuelist); + + WARN_ON(__arq->state != AS_RQ_QUEUED); + } + + /* + * kill knowledge of next, this one is a goner + */ + as_remove_queued_request(q, next); + as_put_io_context(anext); + + anext->state = AS_RQ_MERGED; +} + +/* + * This is executed in a "deferred" process context, by kblockd. It calls the + * driver's request_fn so the driver can submit that request. + * + * IMPORTANT! This guy will reenter the elevator, so set up all queue global + * state before calling, and don't rely on any state over calls. + * + * FIXME! dispatch queue is not a queue at all! + */ +static void as_work_handler(void *data) +{ + struct request_queue *q = data; + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + if (!as_queue_empty(q)) + q->request_fn(q); + spin_unlock_irqrestore(q->queue_lock, flags); +} + +static void as_put_request(request_queue_t *q, struct request *rq) +{ + struct as_data *ad = q->elevator->elevator_data; + struct as_rq *arq = RQ_DATA(rq); + + if (!arq) { + WARN_ON(1); + return; + } + + if (unlikely(arq->state != AS_RQ_POSTSCHED && + arq->state != AS_RQ_PRESCHED && + arq->state != AS_RQ_MERGED)) { + printk("arq->state %d\n", arq->state); + WARN_ON(1); + } + + mempool_free(arq, ad->arq_pool); + rq->elevator_private = NULL; +} + +static int as_set_request(request_queue_t *q, struct request *rq, + struct bio *bio, gfp_t gfp_mask) +{ + struct as_data *ad = q->elevator->elevator_data; + struct as_rq *arq = mempool_alloc(ad->arq_pool, gfp_mask); + + if (arq) { + memset(arq, 0, sizeof(*arq)); + RB_CLEAR(&arq->rb_node); + arq->request = rq; + arq->state = AS_RQ_PRESCHED; + arq->io_context = NULL; + INIT_LIST_HEAD(&arq->hash); + arq->on_hash = 0; + INIT_LIST_HEAD(&arq->fifo); + rq->elevator_private = arq; + return 0; + } + + return 1; +} + +static int as_may_queue(request_queue_t *q, int rw, struct bio *bio) +{ + int ret = ELV_MQUEUE_MAY; + struct as_data *ad = q->elevator->elevator_data; + struct io_context *ioc; + if (ad->antic_status == ANTIC_WAIT_REQ || + ad->antic_status == ANTIC_WAIT_NEXT) { + ioc = as_get_io_context(); + if (ad->io_context == ioc) + ret = ELV_MQUEUE_MUST; + put_io_context(ioc); + } + + return ret; +} + +static void as_exit_queue(elevator_t *e) +{ + struct as_data *ad = e->elevator_data; + + del_timer_sync(&ad->antic_timer); + kblockd_flush(); + + BUG_ON(!list_empty(&ad->fifo_list[REQ_SYNC])); + BUG_ON(!list_empty(&ad->fifo_list[REQ_ASYNC])); + + mempool_destroy(ad->arq_pool); + put_io_context(ad->io_context); + kfree(ad->hash); + kfree(ad); +} + +/* + * initialize elevator private data (as_data), and alloc a arq for + * each request on the free lists + */ +static int as_init_queue(request_queue_t *q, elevator_t *e) +{ + struct as_data *ad; + int i; + + if (!arq_pool) + return -ENOMEM; + + ad = kmalloc_node(sizeof(*ad), GFP_KERNEL, q->node); + if (!ad) + return -ENOMEM; + memset(ad, 0, sizeof(*ad)); + + ad->q = q; /* Identify what queue the data belongs to */ + + ad->hash = kmalloc_node(sizeof(struct list_head)*AS_HASH_ENTRIES, + GFP_KERNEL, q->node); + if (!ad->hash) { + kfree(ad); + return -ENOMEM; + } + + ad->arq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, + mempool_free_slab, arq_pool, q->node); + if (!ad->arq_pool) { + kfree(ad->hash); + kfree(ad); + return -ENOMEM; + } + + /* anticipatory scheduling helpers */ + ad->antic_timer.function = as_antic_timeout; + ad->antic_timer.data = (unsigned long)q; + init_timer(&ad->antic_timer); + INIT_WORK(&ad->antic_work, as_work_handler, q); + + for (i = 0; i < AS_HASH_ENTRIES; i++) + INIT_LIST_HEAD(&ad->hash[i]); + + INIT_LIST_HEAD(&ad->fifo_list[REQ_SYNC]); + INIT_LIST_HEAD(&ad->fifo_list[REQ_ASYNC]); + ad->sort_list[REQ_SYNC] = RB_ROOT; + ad->sort_list[REQ_ASYNC] = RB_ROOT; + ad->fifo_expire[REQ_SYNC] = default_read_expire; + ad->fifo_expire[REQ_ASYNC] = default_write_expire; + ad->antic_expire = default_antic_expire; + ad->batch_expire[REQ_SYNC] = default_read_batch_expire; + ad->batch_expire[REQ_ASYNC] = default_write_batch_expire; + e->elevator_data = ad; + + ad->current_batch_expires = jiffies + ad->batch_expire[REQ_SYNC]; + ad->write_batch_count = ad->batch_expire[REQ_ASYNC] / 10; + if (ad->write_batch_count < 2) + ad->write_batch_count = 2; + + return 0; +} + +/* + * sysfs parts below + */ +struct as_fs_entry { + struct attribute attr; + ssize_t (*show)(struct as_data *, char *); + ssize_t (*store)(struct as_data *, const char *, size_t); +}; + +static ssize_t +as_var_show(unsigned int var, char *page) +{ + return sprintf(page, "%d\n", var); +} + +static ssize_t +as_var_store(unsigned long *var, const char *page, size_t count) +{ + char *p = (char *) page; + + *var = simple_strtoul(p, &p, 10); + return count; +} + +static ssize_t as_est_show(struct as_data *ad, char *page) +{ + int pos = 0; + + pos += sprintf(page+pos, "%lu %% exit probability\n", + 100*ad->exit_prob/256); + pos += sprintf(page+pos, "%lu %% probability of exiting without a " + "cooperating process submitting IO\n", + 100*ad->exit_no_coop/256); + pos += sprintf(page+pos, "%lu ms new thinktime\n", ad->new_ttime_mean); + pos += sprintf(page+pos, "%llu sectors new seek distance\n", + (unsigned long long)ad->new_seek_mean); + + return pos; +} + +#define SHOW_FUNCTION(__FUNC, __VAR) \ +static ssize_t __FUNC(struct as_data *ad, char *page) \ +{ \ + return as_var_show(jiffies_to_msecs((__VAR)), (page)); \ +} +SHOW_FUNCTION(as_readexpire_show, ad->fifo_expire[REQ_SYNC]); +SHOW_FUNCTION(as_writeexpire_show, ad->fifo_expire[REQ_ASYNC]); +SHOW_FUNCTION(as_anticexpire_show, ad->antic_expire); +SHOW_FUNCTION(as_read_batchexpire_show, ad->batch_expire[REQ_SYNC]); +SHOW_FUNCTION(as_write_batchexpire_show, ad->batch_expire[REQ_ASYNC]); +#undef SHOW_FUNCTION + +#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX) \ +static ssize_t __FUNC(struct as_data *ad, const char *page, size_t count) \ +{ \ + int ret = as_var_store(__PTR, (page), count); \ + if (*(__PTR) < (MIN)) \ + *(__PTR) = (MIN); \ + else if (*(__PTR) > (MAX)) \ + *(__PTR) = (MAX); \ + *(__PTR) = msecs_to_jiffies(*(__PTR)); \ + return ret; \ +} +STORE_FUNCTION(as_readexpire_store, &ad->fifo_expire[REQ_SYNC], 0, INT_MAX); +STORE_FUNCTION(as_writeexpire_store, &ad->fifo_expire[REQ_ASYNC], 0, INT_MAX); +STORE_FUNCTION(as_anticexpire_store, &ad->antic_expire, 0, INT_MAX); +STORE_FUNCTION(as_read_batchexpire_store, + &ad->batch_expire[REQ_SYNC], 0, INT_MAX); +STORE_FUNCTION(as_write_batchexpire_store, + &ad->batch_expire[REQ_ASYNC], 0, INT_MAX); +#undef STORE_FUNCTION + +static struct as_fs_entry as_est_entry = { + .attr = {.name = "est_time", .mode = S_IRUGO }, + .show = as_est_show, +}; +static struct as_fs_entry as_readexpire_entry = { + .attr = {.name = "read_expire", .mode = S_IRUGO | S_IWUSR }, + .show = as_readexpire_show, + .store = as_readexpire_store, +}; +static struct as_fs_entry as_writeexpire_entry = { + .attr = {.name = "write_expire", .mode = S_IRUGO | S_IWUSR }, + .show = as_writeexpire_show, + .store = as_writeexpire_store, +}; +static struct as_fs_entry as_anticexpire_entry = { + .attr = {.name = "antic_expire", .mode = S_IRUGO | S_IWUSR }, + .show = as_anticexpire_show, + .store = as_anticexpire_store, +}; +static struct as_fs_entry as_read_batchexpire_entry = { + .attr = {.name = "read_batch_expire", .mode = S_IRUGO | S_IWUSR }, + .show = as_read_batchexpire_show, + .store = as_read_batchexpire_store, +}; +static struct as_fs_entry as_write_batchexpire_entry = { + .attr = {.name = "write_batch_expire", .mode = S_IRUGO | S_IWUSR }, + .show = as_write_batchexpire_show, + .store = as_write_batchexpire_store, +}; + +static struct attribute *default_attrs[] = { + &as_est_entry.attr, + &as_readexpire_entry.attr, + &as_writeexpire_entry.attr, + &as_anticexpire_entry.attr, + &as_read_batchexpire_entry.attr, + &as_write_batchexpire_entry.attr, + NULL, +}; + +#define to_as(atr) container_of((atr), struct as_fs_entry, attr) + +static ssize_t +as_attr_show(struct kobject *kobj, struct attribute *attr, char *page) +{ + elevator_t *e = container_of(kobj, elevator_t, kobj); + struct as_fs_entry *entry = to_as(attr); + + if (!entry->show) + return -EIO; + + return entry->show(e->elevator_data, page); +} + +static ssize_t +as_attr_store(struct kobject *kobj, struct attribute *attr, + const char *page, size_t length) +{ + elevator_t *e = container_of(kobj, elevator_t, kobj); + struct as_fs_entry *entry = to_as(attr); + + if (!entry->store) + return -EIO; + + return entry->store(e->elevator_data, page, length); +} + +static struct sysfs_ops as_sysfs_ops = { + .show = as_attr_show, + .store = as_attr_store, +}; + +static struct kobj_type as_ktype = { + .sysfs_ops = &as_sysfs_ops, + .default_attrs = default_attrs, +}; + +static struct elevator_type iosched_as = { + .ops = { + .elevator_merge_fn = as_merge, + .elevator_merged_fn = as_merged_request, + .elevator_merge_req_fn = as_merged_requests, + .elevator_dispatch_fn = as_dispatch_request, + .elevator_add_req_fn = as_add_request, + .elevator_activate_req_fn = as_activate_request, + .elevator_deactivate_req_fn = as_deactivate_request, + .elevator_queue_empty_fn = as_queue_empty, + .elevator_completed_req_fn = as_completed_request, + .elevator_former_req_fn = as_former_request, + .elevator_latter_req_fn = as_latter_request, + .elevator_set_req_fn = as_set_request, + .elevator_put_req_fn = as_put_request, + .elevator_may_queue_fn = as_may_queue, + .elevator_init_fn = as_init_queue, + .elevator_exit_fn = as_exit_queue, + }, + + .elevator_ktype = &as_ktype, + .elevator_name = "anticipatory", + .elevator_owner = THIS_MODULE, +}; + +static int __init as_init(void) +{ + int ret; + + arq_pool = kmem_cache_create("as_arq", sizeof(struct as_rq), + 0, 0, NULL, NULL); + if (!arq_pool) + return -ENOMEM; + + ret = elv_register(&iosched_as); + if (!ret) { + /* + * don't allow AS to get unregistered, since we would have + * to browse all tasks in the system and release their + * as_io_context first + */ + __module_get(THIS_MODULE); + return 0; + } + + kmem_cache_destroy(arq_pool); + return ret; +} + +static void __exit as_exit(void) +{ + elv_unregister(&iosched_as); + kmem_cache_destroy(arq_pool); +} + +module_init(as_init); +module_exit(as_exit); + +MODULE_AUTHOR("Nick Piggin"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("anticipatory IO scheduler"); diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c new file mode 100644 index 00000000000..ecacca9c877 --- /dev/null +++ b/block/cfq-iosched.c @@ -0,0 +1,2428 @@ +/* + * linux/drivers/block/cfq-iosched.c + * + * CFQ, or complete fairness queueing, disk scheduler. + * + * Based on ideas from a previously unfinished io + * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. + * + * Copyright (C) 2003 Jens Axboe <axboe@suse.de> + */ +#include <linux/kernel.h> +#include <linux/fs.h> +#include <linux/blkdev.h> +#include <linux/elevator.h> +#include <linux/bio.h> +#include <linux/config.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/compiler.h> +#include <linux/hash.h> +#include <linux/rbtree.h> +#include <linux/mempool.h> +#include <linux/ioprio.h> +#include <linux/writeback.h> + +/* + * tunables + */ +static int cfq_quantum = 4; /* max queue in one round of service */ +static int cfq_queued = 8; /* minimum rq allocate limit per-queue*/ +static int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; +static int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */ +static int cfq_back_penalty = 2; /* penalty of a backwards seek */ + +static int cfq_slice_sync = HZ / 10; +static int cfq_slice_async = HZ / 25; +static int cfq_slice_async_rq = 2; +static int cfq_slice_idle = HZ / 100; + +#define CFQ_IDLE_GRACE (HZ / 10) +#define CFQ_SLICE_SCALE (5) + +#define CFQ_KEY_ASYNC (0) +#define CFQ_KEY_ANY (0xffff) + +/* + * disable queueing at the driver/hardware level + */ +static int cfq_max_depth = 2; + +/* + * for the hash of cfqq inside the cfqd + */ +#define CFQ_QHASH_SHIFT 6 +#define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT) +#define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash) + +/* + * for the hash of crq inside the cfqq + */ +#define CFQ_MHASH_SHIFT 6 +#define CFQ_MHASH_BLOCK(sec) ((sec) >> 3) +#define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT) +#define CFQ_MHASH_FN(sec) hash_long(CFQ_MHASH_BLOCK(sec), CFQ_MHASH_SHIFT) +#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) +#define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash) + +#define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list) +#define list_entry_fifo(ptr) list_entry((ptr), struct request, queuelist) + +#define RQ_DATA(rq) (rq)->elevator_private + +/* + * rb-tree defines + */ +#define RB_NONE (2) +#define RB_EMPTY(node) ((node)->rb_node == NULL) +#define RB_CLEAR_COLOR(node) (node)->rb_color = RB_NONE +#define RB_CLEAR(node) do { \ + (node)->rb_parent = NULL; \ + RB_CLEAR_COLOR((node)); \ + (node)->rb_right = NULL; \ + (node)->rb_left = NULL; \ +} while (0) +#define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL) +#define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node) +#define rq_rb_key(rq) (rq)->sector + +static kmem_cache_t *crq_pool; +static kmem_cache_t *cfq_pool; +static kmem_cache_t *cfq_ioc_pool; + +#define CFQ_PRIO_LISTS IOPRIO_BE_NR +#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) +#define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE) +#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) + +#define ASYNC (0) +#define SYNC (1) + +#define cfq_cfqq_dispatched(cfqq) \ + ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC]) + +#define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC) + +#define cfq_cfqq_sync(cfqq) \ + (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC]) + +/* + * Per block device queue structure + */ +struct cfq_data { + atomic_t ref; + request_queue_t *queue; + + /* + * rr list of queues with requests and the count of them + */ + struct list_head rr_list[CFQ_PRIO_LISTS]; + struct list_head busy_rr; + struct list_head cur_rr; + struct list_head idle_rr; + unsigned int busy_queues; + + /* + * non-ordered list of empty cfqq's + */ + struct list_head empty_list; + + /* + * cfqq lookup hash + */ + struct hlist_head *cfq_hash; + + /* + * global crq hash for all queues + */ + struct hlist_head *crq_hash; + + unsigned int max_queued; + + mempool_t *crq_pool; + + int rq_in_driver; + + /* + * schedule slice state info + */ + /* + * idle window management + */ + struct timer_list idle_slice_timer; + struct work_struct unplug_work; + + struct cfq_queue *active_queue; + struct cfq_io_context *active_cic; + int cur_prio, cur_end_prio; + unsigned int dispatch_slice; + + struct timer_list idle_class_timer; + + sector_t last_sector; + unsigned long last_end_request; + + unsigned int rq_starved; + + /* + * tunables, see top of file + */ + unsigned int cfq_quantum; + unsigned int cfq_queued; + unsigned int cfq_fifo_expire[2]; + unsigned int cfq_back_penalty; + unsigned int cfq_back_max; + unsigned int cfq_slice[2]; + unsigned int cfq_slice_async_rq; + unsigned int cfq_slice_idle; + unsigned int cfq_max_depth; +}; + +/* + * Per process-grouping structure + */ +struct cfq_queue { + /* reference count */ + atomic_t ref; + /* parent cfq_data */ + struct cfq_data *cfqd; + /* cfqq lookup hash */ + struct hlist_node cfq_hash; + /* hash key */ + unsigned int key; + /* on either rr or empty list of cfqd */ + struct list_head cfq_list; + /* sorted list of pending requests */ + struct rb_root sort_list; + /* if fifo isn't expired, next request to serve */ + struct cfq_rq *next_crq; + /* requests queued in sort_list */ + int queued[2]; + /* currently allocated requests */ + int allocated[2]; + /* fifo list of requests in sort_list */ + struct list_head fifo; + + unsigned long slice_start; + unsigned long slice_end; + unsigned long slice_left; + unsigned long service_last; + + /* number of requests that are on the dispatch list */ + int on_dispatch[2]; + + /* io prio of this group */ + unsigned short ioprio, org_ioprio; + unsigned short ioprio_class, org_ioprio_class; + + /* various state flags, see below */ + unsigned int flags; +}; + +struct cfq_rq { + struct rb_node rb_node; + sector_t rb_key; + struct request *request; + struct hlist_node hash; + + struct cfq_queue *cfq_queue; + struct cfq_io_context *io_context; + + unsigned int crq_flags; +}; + +enum cfqq_state_flags { + CFQ_CFQQ_FLAG_on_rr = 0, + CFQ_CFQQ_FLAG_wait_request, + CFQ_CFQQ_FLAG_must_alloc, + CFQ_CFQQ_FLAG_must_alloc_slice, + CFQ_CFQQ_FLAG_must_dispatch, + CFQ_CFQQ_FLAG_fifo_expire, + CFQ_CFQQ_FLAG_idle_window, + CFQ_CFQQ_FLAG_prio_changed, + CFQ_CFQQ_FLAG_expired, +}; + +#define CFQ_CFQQ_FNS(name) \ +static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ +{ \ + cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ +} \ +static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ +{ \ + cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ +} \ +static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ +{ \ + return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ +} + +CFQ_CFQQ_FNS(on_rr); +CFQ_CFQQ_FNS(wait_request); +CFQ_CFQQ_FNS(must_alloc); +CFQ_CFQQ_FNS(must_alloc_slice); +CFQ_CFQQ_FNS(must_dispatch); +CFQ_CFQQ_FNS(fifo_expire); +CFQ_CFQQ_FNS(idle_window); +CFQ_CFQQ_FNS(prio_changed); +CFQ_CFQQ_FNS(expired); +#undef CFQ_CFQQ_FNS + +enum cfq_rq_state_flags { + CFQ_CRQ_FLAG_is_sync = 0, +}; + +#define CFQ_CRQ_FNS(name) \ +static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \ +{ \ + crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \ +} \ +static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \ +{ \ + crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \ +} \ +static inline int cfq_crq_##name(const struct cfq_rq *crq) \ +{ \ + return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \ +} + +CFQ_CRQ_FNS(is_sync); +#undef CFQ_CRQ_FNS + +static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short); +static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *); +static void cfq_put_cfqd(struct cfq_data *cfqd); + +#define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE) + +/* + * lots of deadline iosched dupes, can be abstracted later... + */ +static inline void cfq_del_crq_hash(struct cfq_rq *crq) +{ + hlist_del_init(&crq->hash); +} + +static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq) +{ + const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request)); + + hlist_add_head(&crq->hash, &cfqd->crq_hash[hash_idx]); +} + +static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset) +{ + struct hlist_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)]; + struct hlist_node *entry, *next; + + hlist_for_each_safe(entry, next, hash_list) { + struct cfq_rq *crq = list_entry_hash(entry); + struct request *__rq = crq->request; + + if (!rq_mergeable(__rq)) { + cfq_del_crq_hash(crq); + continue; + } + + if (rq_hash_key(__rq) == offset) + return __rq; + } + + return NULL; +} + +/* + * scheduler run of queue, if there are requests pending and no one in the + * driver that will restart queueing + */ +static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) +{ + if (!cfqd->rq_in_driver && cfqd->busy_queues) + kblockd_schedule_work(&cfqd->unplug_work); +} + +static int cfq_queue_empty(request_queue_t *q) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + + return !cfqd->busy_queues; +} + +/* + * Lifted from AS - choose which of crq1 and crq2 that is best served now. + * We choose the request that is closest to the head right now. Distance + * behind the head are penalized and only allowed to a certain extent. + */ +static struct cfq_rq * +cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2) +{ + sector_t last, s1, s2, d1 = 0, d2 = 0; + int r1_wrap = 0, r2_wrap = 0; /* requests are behind the disk head */ + unsigned long back_max; + + if (crq1 == NULL || crq1 == crq2) + return crq2; + if (crq2 == NULL) + return crq1; + + if (cfq_crq_is_sync(crq1) && !cfq_crq_is_sync(crq2)) + return crq1; + else if (cfq_crq_is_sync(crq2) && !cfq_crq_is_sync(crq1)) + return crq2; + + s1 = crq1->request->sector; + s2 = crq2->request->sector; + + last = cfqd->last_sector; + + /* + * by definition, 1KiB is 2 sectors + */ + back_max = cfqd->cfq_back_max * 2; + + /* + * Strict one way elevator _except_ in the case where we allow + * short backward seeks which are biased as twice the cost of a + * similar forward seek. + */ + if (s1 >= last) + d1 = s1 - last; + else if (s1 + back_max >= last) + d1 = (last - s1) * cfqd->cfq_back_penalty; + else + r1_wrap = 1; + + if (s2 >= last) + d2 = s2 - last; + else if (s2 + back_max >= last) + d2 = (last - s2) * cfqd->cfq_back_penalty; + else + r2_wrap = 1; + + /* Found required data */ + if (!r1_wrap && r2_wrap) + return crq1; + else if (!r2_wrap && r1_wrap) + return crq2; + else if (r1_wrap && r2_wrap) { + /* both behind the head */ + if (s1 <= s2) + return crq1; + else + return crq2; + } + + /* Both requests in front of the head */ + if (d1 < d2) + return crq1; + else if (d2 < d1) + return crq2; + else { + if (s1 >= s2) + return crq1; + else + return crq2; + } +} + +/* + * would be nice to take fifo expire time into account as well + */ +static struct cfq_rq * +cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq, + struct cfq_rq *last) +{ + struct cfq_rq *crq_next = NULL, *crq_prev = NULL; + struct rb_node *rbnext, *rbprev; + + if (!(rbnext = rb_next(&last->rb_node))) { + rbnext = rb_first(&cfqq->sort_list); + if (rbnext == &last->rb_node) + rbnext = NULL; + } + + rbprev = rb_prev(&last->rb_node); + + if (rbprev) + crq_prev = rb_entry_crq(rbprev); + if (rbnext) + crq_next = rb_entry_crq(rbnext); + + return cfq_choose_req(cfqd, crq_next, crq_prev); +} + +static void cfq_update_next_crq(struct cfq_rq *crq) +{ + struct cfq_queue *cfqq = crq->cfq_queue; + + if (cfqq->next_crq == crq) + cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq); +} + +static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted) +{ + struct cfq_data *cfqd = cfqq->cfqd; + struct list_head *list, *entry; + + BUG_ON(!cfq_cfqq_on_rr(cfqq)); + + list_del(&cfqq->cfq_list); + + if (cfq_class_rt(cfqq)) + list = &cfqd->cur_rr; + else if (cfq_class_idle(cfqq)) + list = &cfqd->idle_rr; + else { + /* + * if cfqq has requests in flight, don't allow it to be + * found in cfq_set_active_queue before it has finished them. + * this is done to increase fairness between a process that + * has lots of io pending vs one that only generates one + * sporadically or synchronously + */ + if (cfq_cfqq_dispatched(cfqq)) + list = &cfqd->busy_rr; + else + list = &cfqd->rr_list[cfqq->ioprio]; + } + + /* + * if queue was preempted, just add to front to be fair. busy_rr + * isn't sorted. + */ + if (preempted || list == &cfqd->busy_rr) { + list_add(&cfqq->cfq_list, list); + return; + } + + /* + * sort by when queue was last serviced + */ + entry = list; + while ((entry = entry->prev) != list) { + struct cfq_queue *__cfqq = list_entry_cfqq(entry); + + if (!__cfqq->service_last) + break; + if (time_before(__cfqq->service_last, cfqq->service_last)) + break; + } + + list_add(&cfqq->cfq_list, entry); +} + +/* + * add to busy list of queues for service, trying to be fair in ordering + * the pending list according to last request service + */ +static inline void +cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + BUG_ON(cfq_cfqq_on_rr(cfqq)); + cfq_mark_cfqq_on_rr(cfqq); + cfqd->busy_queues++; + + cfq_resort_rr_list(cfqq, 0); +} + +static inline void +cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + BUG_ON(!cfq_cfqq_on_rr(cfqq)); + cfq_clear_cfqq_on_rr(cfqq); + list_move(&cfqq->cfq_list, &cfqd->empty_list); + + BUG_ON(!cfqd->busy_queues); + cfqd->busy_queues--; +} + +/* + * rb tree support functions + */ +static inline void cfq_del_crq_rb(struct cfq_rq *crq) +{ + struct cfq_queue *cfqq = crq->cfq_queue; + struct cfq_data *cfqd = cfqq->cfqd; + const int sync = cfq_crq_is_sync(crq); + + BUG_ON(!cfqq->queued[sync]); + cfqq->queued[sync]--; + + cfq_update_next_crq(crq); + + rb_erase(&crq->rb_node, &cfqq->sort_list); + RB_CLEAR_COLOR(&crq->rb_node); + + if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY(&cfqq->sort_list)) + cfq_del_cfqq_rr(cfqd, cfqq); +} + +static struct cfq_rq * +__cfq_add_crq_rb(struct cfq_rq *crq) +{ + struct rb_node **p = &crq->cfq_queue->sort_list.rb_node; + struct rb_node *parent = NULL; + struct cfq_rq *__crq; + + while (*p) { + parent = *p; + __crq = rb_entry_crq(parent); + + if (crq->rb_key < __crq->rb_key) + p = &(*p)->rb_left; + else if (crq->rb_key > __crq->rb_key) + p = &(*p)->rb_right; + else + return __crq; + } + + rb_link_node(&crq->rb_node, parent, p); + return NULL; +} + +static void cfq_add_crq_rb(struct cfq_rq *crq) +{ + struct cfq_queue *cfqq = crq->cfq_queue; + struct cfq_data *cfqd = cfqq->cfqd; + struct request *rq = crq->request; + struct cfq_rq *__alias; + + crq->rb_key = rq_rb_key(rq); + cfqq->queued[cfq_crq_is_sync(crq)]++; + + /* + * looks a little odd, but the first insert might return an alias. + * if that happens, put the alias on the dispatch list + */ + while ((__alias = __cfq_add_crq_rb(crq)) != NULL) + cfq_dispatch_insert(cfqd->queue, __alias); + + rb_insert_color(&crq->rb_node, &cfqq->sort_list); + + if (!cfq_cfqq_on_rr(cfqq)) + cfq_add_cfqq_rr(cfqd, cfqq); + + /* + * check if this request is a better next-serve candidate + */ + cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq); +} + +static inline void +cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq) +{ + rb_erase(&crq->rb_node, &cfqq->sort_list); + cfqq->queued[cfq_crq_is_sync(crq)]--; + + cfq_add_crq_rb(crq); +} + +static struct request *cfq_find_rq_rb(struct cfq_data *cfqd, sector_t sector) + +{ + struct cfq_queue *cfqq = cfq_find_cfq_hash(cfqd, current->pid, CFQ_KEY_ANY); + struct rb_node *n; + + if (!cfqq) + goto out; + + n = cfqq->sort_list.rb_node; + while (n) { + struct cfq_rq *crq = rb_entry_crq(n); + + if (sector < crq->rb_key) + n = n->rb_left; + else if (sector > crq->rb_key) + n = n->rb_right; + else + return crq->request; + } + +out: + return NULL; +} + +static void cfq_activate_request(request_queue_t *q, struct request *rq) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + + cfqd->rq_in_driver++; +} + +static void cfq_deactivate_request(request_queue_t *q, struct request *rq) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + + WARN_ON(!cfqd->rq_in_driver); + cfqd->rq_in_driver--; +} + +static void cfq_remove_request(struct request *rq) +{ + struct cfq_rq *crq = RQ_DATA(rq); + + list_del_init(&rq->queuelist); + cfq_del_crq_rb(crq); + cfq_del_crq_hash(crq); +} + +static int +cfq_merge(request_queue_t *q, struct request **req, struct bio *bio) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct request *__rq; + int ret; + + __rq = cfq_find_rq_hash(cfqd, bio->bi_sector); + if (__rq && elv_rq_merge_ok(__rq, bio)) { + ret = ELEVATOR_BACK_MERGE; + goto out; + } + + __rq = cfq_find_rq_rb(cfqd, bio->bi_sector + bio_sectors(bio)); + if (__rq && elv_rq_merge_ok(__rq, bio)) { + ret = ELEVATOR_FRONT_MERGE; + goto out; + } + + return ELEVATOR_NO_MERGE; +out: + *req = __rq; + return ret; +} + +static void cfq_merged_request(request_queue_t *q, struct request *req) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_rq *crq = RQ_DATA(req); + + cfq_del_crq_hash(crq); + cfq_add_crq_hash(cfqd, crq); + + if (rq_rb_key(req) != crq->rb_key) { + struct cfq_queue *cfqq = crq->cfq_queue; + + cfq_update_next_crq(crq); + cfq_reposition_crq_rb(cfqq, crq); + } +} + +static void +cfq_merged_requests(request_queue_t *q, struct request *rq, + struct request *next) +{ + cfq_merged_request(q, rq); + + /* + * reposition in fifo if next is older than rq + */ + if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && + time_before(next->start_time, rq->start_time)) + list_move(&rq->queuelist, &next->queuelist); + + cfq_remove_request(next); +} + +static inline void +__cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + if (cfqq) { + /* + * stop potential idle class queues waiting service + */ + del_timer(&cfqd->idle_class_timer); + + cfqq->slice_start = jiffies; + cfqq->slice_end = 0; + cfqq->slice_left = 0; + cfq_clear_cfqq_must_alloc_slice(cfqq); + cfq_clear_cfqq_fifo_expire(cfqq); + cfq_clear_cfqq_expired(cfqq); + } + + cfqd->active_queue = cfqq; +} + +/* + * 0 + * 0,1 + * 0,1,2 + * 0,1,2,3 + * 0,1,2,3,4 + * 0,1,2,3,4,5 + * 0,1,2,3,4,5,6 + * 0,1,2,3,4,5,6,7 + */ +static int cfq_get_next_prio_level(struct cfq_data *cfqd) +{ + int prio, wrap; + + prio = -1; + wrap = 0; + do { + int p; + + for (p = cfqd->cur_prio; p <= cfqd->cur_end_prio; p++) { + if (!list_empty(&cfqd->rr_list[p])) { + prio = p; + break; + } + } + + if (prio != -1) + break; + cfqd->cur_prio = 0; + if (++cfqd->cur_end_prio == CFQ_PRIO_LISTS) { + cfqd->cur_end_prio = 0; + if (wrap) + break; + wrap = 1; + } + } while (1); + + if (unlikely(prio == -1)) + return -1; + + BUG_ON(prio >= CFQ_PRIO_LISTS); + + list_splice_init(&cfqd->rr_list[prio], &cfqd->cur_rr); + + cfqd->cur_prio = prio + 1; + if (cfqd->cur_prio > cfqd->cur_end_prio) { + cfqd->cur_end_prio = cfqd->cur_prio; + cfqd->cur_prio = 0; + } + if (cfqd->cur_end_prio == CFQ_PRIO_LISTS) { + cfqd->cur_prio = 0; + cfqd->cur_end_prio = 0; + } + + return prio; +} + +static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) +{ + struct cfq_queue *cfqq; + + /* + * if current queue is expired but not done with its requests yet, + * wait for that to happen + */ + if ((cfqq = cfqd->active_queue) != NULL) { + if (cfq_cfqq_expired(cfqq) && cfq_cfqq_dispatched(cfqq)) + return NULL; + } + + /* + * if current list is non-empty, grab first entry. if it is empty, + * get next prio level and grab first entry then if any are spliced + */ + if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1) + cfqq = list_entry_cfqq(cfqd->cur_rr.next); + + /* + * if we have idle queues and no rt or be queues had pending + * requests, either allow immediate service if the grace period + * has passed or arm the idle grace timer + */ + if (!cfqq && !list_empty(&cfqd->idle_rr)) { + unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE; + + if (time_after_eq(jiffies, end)) + cfqq = list_entry_cfqq(cfqd->idle_rr.next); + else + mod_timer(&cfqd->idle_class_timer, end); + } + + __cfq_set_active_queue(cfqd, cfqq); + return cfqq; +} + +/* + * current cfqq expired its slice (or was too idle), select new one + */ +static void +__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, + int preempted) +{ + unsigned long now = jiffies; + + if (cfq_cfqq_wait_request(cfqq)) + del_timer(&cfqd->idle_slice_timer); + + if (!preempted && !cfq_cfqq_dispatched(cfqq)) + cfqq->service_last = now; + + cfq_clear_cfqq_must_dispatch(cfqq); + cfq_clear_cfqq_wait_request(cfqq); + + /* + * store what was left of this slice, if the queue idled out + * or was preempted + */ + if (time_after(now, cfqq->slice_end)) + cfqq->slice_left = now - cfqq->slice_end; + else + cfqq->slice_left = 0; + + if (cfq_cfqq_on_rr(cfqq)) + cfq_resort_rr_list(cfqq, preempted); + + if (cfqq == cfqd->active_queue) + cfqd->active_queue = NULL; + + if (cfqd->active_cic) { + put_io_context(cfqd->active_cic->ioc); + cfqd->active_cic = NULL; + } + + cfqd->dispatch_slice = 0; +} + +static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted) +{ + struct cfq_queue *cfqq = cfqd->active_queue; + + if (cfqq) { + /* + * use deferred expiry, if there are requests in progress as + * not to disturb the slice of the next queue + */ + if (cfq_cfqq_dispatched(cfqq)) + cfq_mark_cfqq_expired(cfqq); + else + __cfq_slice_expired(cfqd, cfqq, preempted); + } +} + +static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) + +{ + WARN_ON(!RB_EMPTY(&cfqq->sort_list)); + WARN_ON(cfqq != cfqd->active_queue); + + /* + * idle is disabled, either manually or by past process history + */ + if (!cfqd->cfq_slice_idle) + return 0; + if (!cfq_cfqq_idle_window(cfqq)) + return 0; + /* + * task has exited, don't wait + */ + if (cfqd->active_cic && !cfqd->active_cic->ioc->task) + return 0; + + cfq_mark_cfqq_must_dispatch(cfqq); + cfq_mark_cfqq_wait_request(cfqq); + + if (!timer_pending(&cfqd->idle_slice_timer)) { + unsigned long slice_left = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle); + + cfqd->idle_slice_timer.expires = jiffies + slice_left; + add_timer(&cfqd->idle_slice_timer); + } + + return 1; +} + +static void cfq_dispatch_insert(request_queue_t *q, struct cfq_rq *crq) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_queue *cfqq = crq->cfq_queue; + + cfqq->next_crq = cfq_find_next_crq(cfqd, cfqq, crq); + cfq_remove_request(crq->request); + cfqq->on_dispatch[cfq_crq_is_sync(crq)]++; + elv_dispatch_sort(q, crq->request); +} + +/* + * return expired entry, or NULL to just start from scratch in rbtree + */ +static inline struct cfq_rq *cfq_check_fifo(struct cfq_queue *cfqq) +{ + struct cfq_data *cfqd = cfqq->cfqd; + struct request *rq; + struct cfq_rq *crq; + + if (cfq_cfqq_fifo_expire(cfqq)) + return NULL; + + if (!list_empty(&cfqq->fifo)) { + int fifo = cfq_cfqq_class_sync(cfqq); + + crq = RQ_DATA(list_entry_fifo(cfqq->fifo.next)); + rq = crq->request; + if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) { + cfq_mark_cfqq_fifo_expire(cfqq); + return crq; + } + } + + return NULL; +} + +/* + * Scale schedule slice based on io priority. Use the sync time slice only + * if a queue is marked sync and has sync io queued. A sync queue with async + * io only, should not get full sync slice length. + */ +static inline int +cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)]; + + WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); + + return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio)); +} + +static inline void +cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; +} + +static inline int +cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + const int base_rq = cfqd->cfq_slice_async_rq; + + WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); + + return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); +} + +/* + * get next queue for service + */ +static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd, int force) +{ + unsigned long now = jiffies; + struct cfq_queue *cfqq; + + cfqq = cfqd->active_queue; + if (!cfqq) + goto new_queue; + + if (cfq_cfqq_expired(cfqq)) + goto new_queue; + + /* + * slice has expired + */ + if (!cfq_cfqq_must_dispatch(cfqq) && time_after(now, cfqq->slice_end)) + goto expire; + + /* + * if queue has requests, dispatch one. if not, check if + * enough slice is left to wait for one + */ + if (!RB_EMPTY(&cfqq->sort_list)) + goto keep_queue; + else if (!force && cfq_cfqq_class_sync(cfqq) && + time_before(now, cfqq->slice_end)) { + if (cfq_arm_slice_timer(cfqd, cfqq)) + return NULL; + } + +expire: + cfq_slice_expired(cfqd, 0); +new_queue: + cfqq = cfq_set_active_queue(cfqd); +keep_queue: + return cfqq; +} + +static int +__cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq, + int max_dispatch) +{ + int dispatched = 0; + + BUG_ON(RB_EMPTY(&cfqq->sort_list)); + + do { + struct cfq_rq *crq; + + /* + * follow expired path, else get first next available + */ + if ((crq = cfq_check_fifo(cfqq)) == NULL) + crq = cfqq->next_crq; + + /* + * finally, insert request into driver dispatch list + */ + cfq_dispatch_insert(cfqd->queue, crq); + + cfqd->dispatch_slice++; + dispatched++; + + if (!cfqd->active_cic) { + atomic_inc(&crq->io_context->ioc->refcount); + cfqd->active_cic = crq->io_context; + } + + if (RB_EMPTY(&cfqq->sort_list)) + break; + + } while (dispatched < max_dispatch); + + /* + * if slice end isn't set yet, set it. if at least one request was + * sync, use the sync time slice value + */ + if (!cfqq->slice_end) + cfq_set_prio_slice(cfqd, cfqq); + + /* + * expire an async queue immediately if it has used up its slice. idle + * queue always expire after 1 dispatch round. + */ + if ((!cfq_cfqq_sync(cfqq) && + cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) || + cfq_class_idle(cfqq)) + cfq_slice_expired(cfqd, 0); + + return dispatched; +} + +static int +cfq_dispatch_requests(request_queue_t *q, int force) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_queue *cfqq; + + if (!cfqd->busy_queues) + return 0; + + cfqq = cfq_select_queue(cfqd, force); + if (cfqq) { + int max_dispatch; + + /* + * if idle window is disabled, allow queue buildup + */ + if (!cfq_cfqq_idle_window(cfqq) && + cfqd->rq_in_driver >= cfqd->cfq_max_depth) + return 0; + + cfq_clear_cfqq_must_dispatch(cfqq); + cfq_clear_cfqq_wait_request(cfqq); + del_timer(&cfqd->idle_slice_timer); + + if (!force) { + max_dispatch = cfqd->cfq_quantum; + if (cfq_class_idle(cfqq)) + max_dispatch = 1; + } else + max_dispatch = INT_MAX; + + return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch); + } + + return 0; +} + +/* + * task holds one reference to the queue, dropped when task exits. each crq + * in-flight on this queue also holds a reference, dropped when crq is freed. + * + * queue lock must be held here. + */ +static void cfq_put_queue(struct cfq_queue *cfqq) +{ + struct cfq_data *cfqd = cfqq->cfqd; + + BUG_ON(atomic_read(&cfqq->ref) <= 0); + + if (!atomic_dec_and_test(&cfqq->ref)) + return; + + BUG_ON(rb_first(&cfqq->sort_list)); + BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); + BUG_ON(cfq_cfqq_on_rr(cfqq)); + + if (unlikely(cfqd->active_queue == cfqq)) { + __cfq_slice_expired(cfqd, cfqq, 0); + cfq_schedule_dispatch(cfqd); + } + + cfq_put_cfqd(cfqq->cfqd); + + /* + * it's on the empty list and still hashed + */ + list_del(&cfqq->cfq_list); + hlist_del(&cfqq->cfq_hash); + kmem_cache_free(cfq_pool, cfqq); +} + +static inline struct cfq_queue * +__cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned int prio, + const int hashval) +{ + struct hlist_head *hash_list = &cfqd->cfq_hash[hashval]; + struct hlist_node *entry, *next; + + hlist_for_each_safe(entry, next, hash_list) { + struct cfq_queue *__cfqq = list_entry_qhash(entry); + const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->ioprio_class, __cfqq->ioprio); + + if (__cfqq->key == key && (__p == prio || prio == CFQ_KEY_ANY)) + return __cfqq; + } + + return NULL; +} + +static struct cfq_queue * +cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned short prio) +{ + return __cfq_find_cfq_hash(cfqd, key, prio, hash_long(key, CFQ_QHASH_SHIFT)); +} + +static void cfq_free_io_context(struct cfq_io_context *cic) +{ + struct cfq_io_context *__cic; + struct list_head *entry, *next; + + list_for_each_safe(entry, next, &cic->list) { + __cic = list_entry(entry, struct cfq_io_context, list); + kmem_cache_free(cfq_ioc_pool, __cic); + } + + kmem_cache_free(cfq_ioc_pool, cic); +} + +/* + * Called with interrupts disabled + */ +static void cfq_exit_single_io_context(struct cfq_io_context *cic) +{ + struct cfq_data *cfqd = cic->cfqq->cfqd; + request_queue_t *q = cfqd->queue; + + WARN_ON(!irqs_disabled()); + + spin_lock(q->queue_lock); + + if (unlikely(cic->cfqq == cfqd->active_queue)) { + __cfq_slice_expired(cfqd, cic->cfqq, 0); + cfq_schedule_dispatch(cfqd); + } + + cfq_put_queue(cic->cfqq); + cic->cfqq = NULL; + spin_unlock(q->queue_lock); +} + +/* + * Another task may update the task cic list, if it is doing a queue lookup + * on its behalf. cfq_cic_lock excludes such concurrent updates + */ +static void cfq_exit_io_context(struct cfq_io_context *cic) +{ + struct cfq_io_context *__cic; + struct list_head *entry; + unsigned long flags; + + local_irq_save(flags); + + /* + * put the reference this task is holding to the various queues + */ + list_for_each(entry, &cic->list) { + __cic = list_entry(entry, struct cfq_io_context, list); + cfq_exit_single_io_context(__cic); + } + + cfq_exit_single_io_context(cic); + local_irq_restore(flags); +} + +static struct cfq_io_context * +cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) +{ + struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_mask); + + if (cic) { + INIT_LIST_HEAD(&cic->list); + cic->cfqq = NULL; + cic->key = NULL; + cic->last_end_request = jiffies; + cic->ttime_total = 0; + cic->ttime_samples = 0; + cic->ttime_mean = 0; + cic->dtor = cfq_free_io_context; + cic->exit = cfq_exit_io_context; + } + + return cic; +} + +static void cfq_init_prio_data(struct cfq_queue *cfqq) +{ + struct task_struct *tsk = current; + int ioprio_class; + + if (!cfq_cfqq_prio_changed(cfqq)) + return; + + ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio); + switch (ioprio_class) { + default: + printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); + case IOPRIO_CLASS_NONE: + /* + * no prio set, place us in the middle of the BE classes + */ + cfqq->ioprio = task_nice_ioprio(tsk); + cfqq->ioprio_class = IOPRIO_CLASS_BE; + break; + case IOPRIO_CLASS_RT: + cfqq->ioprio = task_ioprio(tsk); + cfqq->ioprio_class = IOPRIO_CLASS_RT; + break; + case IOPRIO_CLASS_BE: + cfqq->ioprio = task_ioprio(tsk); + cfqq->ioprio_class = IOPRIO_CLASS_BE; + break; + case IOPRIO_CLASS_IDLE: + cfqq->ioprio_class = IOPRIO_CLASS_IDLE; + cfqq->ioprio = 7; + cfq_clear_cfqq_idle_window(cfqq); + break; + } + + /* + * keep track of original prio settings in case we have to temporarily + * elevate the priority of this queue + */ + cfqq->org_ioprio = cfqq->ioprio; + cfqq->org_ioprio_class = cfqq->ioprio_class; + + if (cfq_cfqq_on_rr(cfqq)) + cfq_resort_rr_list(cfqq, 0); + + cfq_clear_cfqq_prio_changed(cfqq); +} + +static inline void changed_ioprio(struct cfq_queue *cfqq) +{ + if (cfqq) { + struct cfq_data *cfqd = cfqq->cfqd; + + spin_lock(cfqd->queue->queue_lock); + cfq_mark_cfqq_prio_changed(cfqq); + cfq_init_prio_data(cfqq); + spin_unlock(cfqd->queue->queue_lock); + } +} + +/* + * callback from sys_ioprio_set, irqs are disabled + */ +static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio) +{ + struct cfq_io_context *cic = ioc->cic; + + changed_ioprio(cic->cfqq); + + list_for_each_entry(cic, &cic->list, list) + changed_ioprio(cic->cfqq); + + return 0; +} + +static struct cfq_queue * +cfq_get_queue(struct cfq_data *cfqd, unsigned int key, unsigned short ioprio, + gfp_t gfp_mask) +{ + const int hashval = hash_long(key, CFQ_QHASH_SHIFT); + struct cfq_queue *cfqq, *new_cfqq = NULL; + +retry: + cfqq = __cfq_find_cfq_hash(cfqd, key, ioprio, hashval); + + if (!cfqq) { + if (new_cfqq) { + cfqq = new_cfqq; + new_cfqq = NULL; + } else if (gfp_mask & __GFP_WAIT) { + spin_unlock_irq(cfqd->queue->queue_lock); + new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); + spin_lock_irq(cfqd->queue->queue_lock); + goto retry; + } else { + cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); + if (!cfqq) + goto out; + } + + memset(cfqq, 0, sizeof(*cfqq)); + + INIT_HLIST_NODE(&cfqq->cfq_hash); + INIT_LIST_HEAD(&cfqq->cfq_list); + RB_CLEAR_ROOT(&cfqq->sort_list); + INIT_LIST_HEAD(&cfqq->fifo); + + cfqq->key = key; + hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]); + atomic_set(&cfqq->ref, 0); + cfqq->cfqd = cfqd; + atomic_inc(&cfqd->ref); + cfqq->service_last = 0; + /* + * set ->slice_left to allow preemption for a new process + */ + cfqq->slice_left = 2 * cfqd->cfq_slice_idle; + cfq_mark_cfqq_idle_window(cfqq); + cfq_mark_cfqq_prio_changed(cfqq); + cfq_init_prio_data(cfqq); + } + + if (new_cfqq) + kmem_cache_free(cfq_pool, new_cfqq); + + atomic_inc(&cfqq->ref); +out: + WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq); + return cfqq; +} + +/* + * Setup general io context and cfq io context. There can be several cfq + * io contexts per general io context, if this process is doing io to more + * than one device managed by cfq. Note that caller is holding a reference to + * cfqq, so we don't need to worry about it disappearing + */ +static struct cfq_io_context * +cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, gfp_t gfp_mask) +{ + struct io_context *ioc = NULL; + struct cfq_io_context *cic; + + might_sleep_if(gfp_mask & __GFP_WAIT); + + ioc = get_io_context(gfp_mask); + if (!ioc) + return NULL; + + if ((cic = ioc->cic) == NULL) { + cic = cfq_alloc_io_context(cfqd, gfp_mask); + + if (cic == NULL) + goto err; + + /* + * manually increment generic io_context usage count, it + * cannot go away since we are already holding one ref to it + */ + ioc->cic = cic; + ioc->set_ioprio = cfq_ioc_set_ioprio; + cic->ioc = ioc; + cic->key = cfqd; + atomic_inc(&cfqd->ref); + } else { + struct cfq_io_context *__cic; + + /* + * the first cic on the list is actually the head itself + */ + if (cic->key == cfqd) + goto out; + + /* + * cic exists, check if we already are there. linear search + * should be ok here, the list will usually not be more than + * 1 or a few entries long + */ + list_for_each_entry(__cic, &cic->list, list) { + /* + * this process is already holding a reference to + * this queue, so no need to get one more + */ + if (__cic->key == cfqd) { + cic = __cic; + goto out; + } + } + + /* + * nope, process doesn't have a cic assoicated with this + * cfqq yet. get a new one and add to list + */ + __cic = cfq_alloc_io_context(cfqd, gfp_mask); + if (__cic == NULL) + goto err; + + __cic->ioc = ioc; + __cic->key = cfqd; + atomic_inc(&cfqd->ref); + list_add(&__cic->list, &cic->list); + cic = __cic; + } + +out: + return cic; +err: + put_io_context(ioc); + return NULL; +} + +static void +cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) +{ + unsigned long elapsed, ttime; + + /* + * if this context already has stuff queued, thinktime is from + * last queue not last end + */ +#if 0 + if (time_after(cic->last_end_request, cic->last_queue)) + elapsed = jiffies - cic->last_end_request; + else + elapsed = jiffies - cic->last_queue; +#else + elapsed = jiffies - cic->last_end_request; +#endif + + ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); + + cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; + cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; + cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; +} + +#define sample_valid(samples) ((samples) > 80) + +/* + * Disable idle window if the process thinks too long or seeks so much that + * it doesn't matter + */ +static void +cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, + struct cfq_io_context *cic) +{ + int enable_idle = cfq_cfqq_idle_window(cfqq); + + if (!cic->ioc->task || !cfqd->cfq_slice_idle) + enable_idle = 0; + else if (sample_valid(cic->ttime_samples)) { + if (cic->ttime_mean > cfqd->cfq_slice_idle) + enable_idle = 0; + else + enable_idle = 1; + } + + if (enable_idle) + cfq_mark_cfqq_idle_window(cfqq); + else + cfq_clear_cfqq_idle_window(cfqq); +} + + +/* + * Check if new_cfqq should preempt the currently active queue. Return 0 for + * no or if we aren't sure, a 1 will cause a preempt. + */ +static int +cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, + struct cfq_rq *crq) +{ + struct cfq_queue *cfqq = cfqd->active_queue; + + if (cfq_class_idle(new_cfqq)) + return 0; + + if (!cfqq) + return 1; + + if (cfq_class_idle(cfqq)) + return 1; + if (!cfq_cfqq_wait_request(new_cfqq)) + return 0; + /* + * if it doesn't have slice left, forget it + */ + if (new_cfqq->slice_left < cfqd->cfq_slice_idle) + return 0; + if (cfq_crq_is_sync(crq) && !cfq_cfqq_sync(cfqq)) + return 1; + + return 0; +} + +/* + * cfqq preempts the active queue. if we allowed preempt with no slice left, + * let it have half of its nominal slice. + */ +static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + struct cfq_queue *__cfqq, *next; + + list_for_each_entry_safe(__cfqq, next, &cfqd->cur_rr, cfq_list) + cfq_resort_rr_list(__cfqq, 1); + + if (!cfqq->slice_left) + cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2; + + cfqq->slice_end = cfqq->slice_left + jiffies; + __cfq_slice_expired(cfqd, cfqq, 1); + __cfq_set_active_queue(cfqd, cfqq); +} + +/* + * should really be a ll_rw_blk.c helper + */ +static void cfq_start_queueing(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + request_queue_t *q = cfqd->queue; + + if (!blk_queue_plugged(q)) + q->request_fn(q); + else + __generic_unplug_device(q); +} + +/* + * Called when a new fs request (crq) is added (to cfqq). Check if there's + * something we should do about it + */ +static void +cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, + struct cfq_rq *crq) +{ + struct cfq_io_context *cic; + + cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq); + + /* + * we never wait for an async request and we don't allow preemption + * of an async request. so just return early + */ + if (!cfq_crq_is_sync(crq)) + return; + + cic = crq->io_context; + + cfq_update_io_thinktime(cfqd, cic); + cfq_update_idle_window(cfqd, cfqq, cic); + + cic->last_queue = jiffies; + + if (cfqq == cfqd->active_queue) { + /* + * if we are waiting for a request for this queue, let it rip + * immediately and flag that we must not expire this queue + * just now + */ + if (cfq_cfqq_wait_request(cfqq)) { + cfq_mark_cfqq_must_dispatch(cfqq); + del_timer(&cfqd->idle_slice_timer); + cfq_start_queueing(cfqd, cfqq); + } + } else if (cfq_should_preempt(cfqd, cfqq, crq)) { + /* + * not the active queue - expire current slice if it is + * idle and has expired it's mean thinktime or this new queue + * has some old slice time left and is of higher priority + */ + cfq_preempt_queue(cfqd, cfqq); + cfq_mark_cfqq_must_dispatch(cfqq); + cfq_start_queueing(cfqd, cfqq); + } +} + +static void cfq_insert_request(request_queue_t *q, struct request *rq) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_rq *crq = RQ_DATA(rq); + struct cfq_queue *cfqq = crq->cfq_queue; + + cfq_init_prio_data(cfqq); + + cfq_add_crq_rb(crq); + + list_add_tail(&rq->queuelist, &cfqq->fifo); + + if (rq_mergeable(rq)) + cfq_add_crq_hash(cfqd, crq); + + cfq_crq_enqueued(cfqd, cfqq, crq); +} + +static void cfq_completed_request(request_queue_t *q, struct request *rq) +{ + struct cfq_rq *crq = RQ_DATA(rq); + struct cfq_queue *cfqq = crq->cfq_queue; + struct cfq_data *cfqd = cfqq->cfqd; + const int sync = cfq_crq_is_sync(crq); + unsigned long now; + + now = jiffies; + + WARN_ON(!cfqd->rq_in_driver); + WARN_ON(!cfqq->on_dispatch[sync]); + cfqd->rq_in_driver--; + cfqq->on_dispatch[sync]--; + + if (!cfq_class_idle(cfqq)) + cfqd->last_end_request = now; + + if (!cfq_cfqq_dispatched(cfqq)) { + if (cfq_cfqq_on_rr(cfqq)) { + cfqq->service_last = now; + cfq_resort_rr_list(cfqq, 0); + } + if (cfq_cfqq_expired(cfqq)) { + __cfq_slice_expired(cfqd, cfqq, 0); + cfq_schedule_dispatch(cfqd); + } + } + + if (cfq_crq_is_sync(crq)) + crq->io_context->last_end_request = now; +} + +static struct request * +cfq_former_request(request_queue_t *q, struct request *rq) +{ + struct cfq_rq *crq = RQ_DATA(rq); + struct rb_node *rbprev = rb_prev(&crq->rb_node); + + if (rbprev) + return rb_entry_crq(rbprev)->request; + + return NULL; +} + +static struct request * +cfq_latter_request(request_queue_t *q, struct request *rq) +{ + struct cfq_rq *crq = RQ_DATA(rq); + struct rb_node *rbnext = rb_next(&crq->rb_node); + + if (rbnext) + return rb_entry_crq(rbnext)->request; + + return NULL; +} + +/* + * we temporarily boost lower priority queues if they are holding fs exclusive + * resources. they are boosted to normal prio (CLASS_BE/4) + */ +static void cfq_prio_boost(struct cfq_queue *cfqq) +{ + const int ioprio_class = cfqq->ioprio_class; + const int ioprio = cfqq->ioprio; + + if (has_fs_excl()) { + /* + * boost idle prio on transactions that would lock out other + * users of the filesystem + */ + if (cfq_class_idle(cfqq)) + cfqq->ioprio_class = IOPRIO_CLASS_BE; + if (cfqq->ioprio > IOPRIO_NORM) + cfqq->ioprio = IOPRIO_NORM; + } else { + /* + * check if we need to unboost the queue + */ + if (cfqq->ioprio_class != cfqq->org_ioprio_class) + cfqq->ioprio_class = cfqq->org_ioprio_class; + if (cfqq->ioprio != cfqq->org_ioprio) + cfqq->ioprio = cfqq->org_ioprio; + } + + /* + * refile between round-robin lists if we moved the priority class + */ + if ((ioprio_class != cfqq->ioprio_class || ioprio != cfqq->ioprio) && + cfq_cfqq_on_rr(cfqq)) + cfq_resort_rr_list(cfqq, 0); +} + +static inline pid_t cfq_queue_pid(struct task_struct *task, int rw) +{ + if (rw == READ || process_sync(task)) + return task->pid; + + return CFQ_KEY_ASYNC; +} + +static inline int +__cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq, + struct task_struct *task, int rw) +{ +#if 1 + if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) && + !cfq_cfqq_must_alloc_slice(cfqq)) { + cfq_mark_cfqq_must_alloc_slice(cfqq); + return ELV_MQUEUE_MUST; + } + + return ELV_MQUEUE_MAY; +#else + if (!cfqq || task->flags & PF_MEMALLOC) + return ELV_MQUEUE_MAY; + if (!cfqq->allocated[rw] || cfq_cfqq_must_alloc(cfqq)) { + if (cfq_cfqq_wait_request(cfqq)) + return ELV_MQUEUE_MUST; + + /* + * only allow 1 ELV_MQUEUE_MUST per slice, otherwise we + * can quickly flood the queue with writes from a single task + */ + if (rw == READ || !cfq_cfqq_must_alloc_slice(cfqq)) { + cfq_mark_cfqq_must_alloc_slice(cfqq); + return ELV_MQUEUE_MUST; + } + + return ELV_MQUEUE_MAY; + } + if (cfq_class_idle(cfqq)) + return ELV_MQUEUE_NO; + if (cfqq->allocated[rw] >= cfqd->max_queued) { + struct io_context *ioc = get_io_context(GFP_ATOMIC); + int ret = ELV_MQUEUE_NO; + + if (ioc && ioc->nr_batch_requests) + ret = ELV_MQUEUE_MAY; + + put_io_context(ioc); + return ret; + } + + return ELV_MQUEUE_MAY; +#endif +} + +static int cfq_may_queue(request_queue_t *q, int rw, struct bio *bio) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct task_struct *tsk = current; + struct cfq_queue *cfqq; + + /* + * don't force setup of a queue from here, as a call to may_queue + * does not necessarily imply that a request actually will be queued. + * so just lookup a possibly existing queue, or return 'may queue' + * if that fails + */ + cfqq = cfq_find_cfq_hash(cfqd, cfq_queue_pid(tsk, rw), tsk->ioprio); + if (cfqq) { + cfq_init_prio_data(cfqq); + cfq_prio_boost(cfqq); + + return __cfq_may_queue(cfqd, cfqq, tsk, rw); + } + + return ELV_MQUEUE_MAY; +} + +static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct request_list *rl = &q->rq; + + if (cfqq->allocated[READ] <= cfqd->max_queued || cfqd->rq_starved) { + smp_mb(); + if (waitqueue_active(&rl->wait[READ])) + wake_up(&rl->wait[READ]); + } + + if (cfqq->allocated[WRITE] <= cfqd->max_queued || cfqd->rq_starved) { + smp_mb(); + if (waitqueue_active(&rl->wait[WRITE])) + wake_up(&rl->wait[WRITE]); + } +} + +/* + * queue lock held here + */ +static void cfq_put_request(request_queue_t *q, struct request *rq) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_rq *crq = RQ_DATA(rq); + + if (crq) { + struct cfq_queue *cfqq = crq->cfq_queue; + const int rw = rq_data_dir(rq); + + BUG_ON(!cfqq->allocated[rw]); + cfqq->allocated[rw]--; + + put_io_context(crq->io_context->ioc); + + mempool_free(crq, cfqd->crq_pool); + rq->elevator_private = NULL; + + cfq_check_waiters(q, cfqq); + cfq_put_queue(cfqq); + } +} + +/* + * Allocate cfq data structures associated with this request. + */ +static int +cfq_set_request(request_queue_t *q, struct request *rq, struct bio *bio, + gfp_t gfp_mask) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct task_struct *tsk = current; + struct cfq_io_context *cic; + const int rw = rq_data_dir(rq); + pid_t key = cfq_queue_pid(tsk, rw); + struct cfq_queue *cfqq; + struct cfq_rq *crq; + unsigned long flags; + + might_sleep_if(gfp_mask & __GFP_WAIT); + + cic = cfq_get_io_context(cfqd, key, gfp_mask); + + spin_lock_irqsave(q->queue_lock, flags); + + if (!cic) + goto queue_fail; + + if (!cic->cfqq) { + cfqq = cfq_get_queue(cfqd, key, tsk->ioprio, gfp_mask); + if (!cfqq) + goto queue_fail; + + cic->cfqq = cfqq; + } else + cfqq = cic->cfqq; + + cfqq->allocated[rw]++; + cfq_clear_cfqq_must_alloc(cfqq); + cfqd->rq_starved = 0; + atomic_inc(&cfqq->ref); + spin_unlock_irqrestore(q->queue_lock, flags); + + crq = mempool_alloc(cfqd->crq_pool, gfp_mask); + if (crq) { + RB_CLEAR(&crq->rb_node); + crq->rb_key = 0; + crq->request = rq; + INIT_HLIST_NODE(&crq->hash); + crq->cfq_queue = cfqq; + crq->io_context = cic; + + if (rw == READ || process_sync(tsk)) + cfq_mark_crq_is_sync(crq); + else + cfq_clear_crq_is_sync(crq); + + rq->elevator_private = crq; + return 0; + } + + spin_lock_irqsave(q->queue_lock, flags); + cfqq->allocated[rw]--; + if (!(cfqq->allocated[0] + cfqq->allocated[1])) + cfq_mark_cfqq_must_alloc(cfqq); + cfq_put_queue(cfqq); +queue_fail: + if (cic) + put_io_context(cic->ioc); + /* + * mark us rq allocation starved. we need to kickstart the process + * ourselves if there are no pending requests that can do it for us. + * that would be an extremely rare OOM situation + */ + cfqd->rq_starved = 1; + cfq_schedule_dispatch(cfqd); + spin_unlock_irqrestore(q->queue_lock, flags); + return 1; +} + +static void cfq_kick_queue(void *data) +{ + request_queue_t *q = data; + struct cfq_data *cfqd = q->elevator->elevator_data; + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + + if (cfqd->rq_starved) { + struct request_list *rl = &q->rq; + + /* + * we aren't guaranteed to get a request after this, but we + * have to be opportunistic + */ + smp_mb(); + if (waitqueue_active(&rl->wait[READ])) + wake_up(&rl->wait[READ]); + if (waitqueue_active(&rl->wait[WRITE])) + wake_up(&rl->wait[WRITE]); + } + + blk_remove_plug(q); + q->request_fn(q); + spin_unlock_irqrestore(q->queue_lock, flags); +} + +/* + * Timer running if the active_queue is currently idling inside its time slice + */ +static void cfq_idle_slice_timer(unsigned long data) +{ + struct cfq_data *cfqd = (struct cfq_data *) data; + struct cfq_queue *cfqq; + unsigned long flags; + + spin_lock_irqsave(cfqd->queue->queue_lock, flags); + + if ((cfqq = cfqd->active_queue) != NULL) { + unsigned long now = jiffies; + + /* + * expired + */ + if (time_after(now, cfqq->slice_end)) + goto expire; + + /* + * only expire and reinvoke request handler, if there are + * other queues with pending requests + */ + if (!cfqd->busy_queues) { + cfqd->idle_slice_timer.expires = min(now + cfqd->cfq_slice_idle, cfqq->slice_end); + add_timer(&cfqd->idle_slice_timer); + goto out_cont; + } + + /* + * not expired and it has a request pending, let it dispatch + */ + if (!RB_EMPTY(&cfqq->sort_list)) { + cfq_mark_cfqq_must_dispatch(cfqq); + goto out_kick; + } + } +expire: + cfq_slice_expired(cfqd, 0); +out_kick: + cfq_schedule_dispatch(cfqd); +out_cont: + spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); +} + +/* + * Timer running if an idle class queue is waiting for service + */ +static void cfq_idle_class_timer(unsigned long data) +{ + struct cfq_data *cfqd = (struct cfq_data *) data; + unsigned long flags, end; + + spin_lock_irqsave(cfqd->queue->queue_lock, flags); + + /* + * race with a non-idle queue, reset timer + */ + end = cfqd->last_end_request + CFQ_IDLE_GRACE; + if (!time_after_eq(jiffies, end)) { + cfqd->idle_class_timer.expires = end; + add_timer(&cfqd->idle_class_timer); + } else + cfq_schedule_dispatch(cfqd); + + spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); +} + +static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) +{ + del_timer_sync(&cfqd->idle_slice_timer); + del_timer_sync(&cfqd->idle_class_timer); + blk_sync_queue(cfqd->queue); +} + +static void cfq_put_cfqd(struct cfq_data *cfqd) +{ + request_queue_t *q = cfqd->queue; + + if (!atomic_dec_and_test(&cfqd->ref)) + return; + + cfq_shutdown_timer_wq(cfqd); + blk_put_queue(q); + + mempool_destroy(cfqd->crq_pool); + kfree(cfqd->crq_hash); + kfree(cfqd->cfq_hash); + kfree(cfqd); +} + +static void cfq_exit_queue(elevator_t *e) +{ + struct cfq_data *cfqd = e->elevator_data; + + cfq_shutdown_timer_wq(cfqd); + cfq_put_cfqd(cfqd); +} + +static int cfq_init_queue(request_queue_t *q, elevator_t *e) +{ + struct cfq_data *cfqd; + int i; + + cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL); + if (!cfqd) + return -ENOMEM; + + memset(cfqd, 0, sizeof(*cfqd)); + + for (i = 0; i < CFQ_PRIO_LISTS; i++) + INIT_LIST_HEAD(&cfqd->rr_list[i]); + + INIT_LIST_HEAD(&cfqd->busy_rr); + INIT_LIST_HEAD(&cfqd->cur_rr); + INIT_LIST_HEAD(&cfqd->idle_rr); + INIT_LIST_HEAD(&cfqd->empty_list); + + cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL); + if (!cfqd->crq_hash) + goto out_crqhash; + + cfqd->cfq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL); + if (!cfqd->cfq_hash) + goto out_cfqhash; + + cfqd->crq_pool = mempool_create(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, crq_pool); + if (!cfqd->crq_pool) + goto out_crqpool; + + for (i = 0; i < CFQ_MHASH_ENTRIES; i++) + INIT_HLIST_HEAD(&cfqd->crq_hash[i]); + for (i = 0; i < CFQ_QHASH_ENTRIES; i++) + INIT_HLIST_HEAD(&cfqd->cfq_hash[i]); + + e->elevator_data = cfqd; + + cfqd->queue = q; + atomic_inc(&q->refcnt); + + cfqd->max_queued = q->nr_requests / 4; + q->nr_batching = cfq_queued; + + init_timer(&cfqd->idle_slice_timer); + cfqd->idle_slice_timer.function = cfq_idle_slice_timer; + cfqd->idle_slice_timer.data = (unsigned long) cfqd; + + init_timer(&cfqd->idle_class_timer); + cfqd->idle_class_timer.function = cfq_idle_class_timer; + cfqd->idle_class_timer.data = (unsigned long) cfqd; + + INIT_WORK(&cfqd->unplug_work, cfq_kick_queue, q); + + atomic_set(&cfqd->ref, 1); + + cfqd->cfq_queued = cfq_queued; + cfqd->cfq_quantum = cfq_quantum; + cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; + cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; + cfqd->cfq_back_max = cfq_back_max; + cfqd->cfq_back_penalty = cfq_back_penalty; + cfqd->cfq_slice[0] = cfq_slice_async; + cfqd->cfq_slice[1] = cfq_slice_sync; + cfqd->cfq_slice_async_rq = cfq_slice_async_rq; + cfqd->cfq_slice_idle = cfq_slice_idle; + cfqd->cfq_max_depth = cfq_max_depth; + + return 0; +out_crqpool: + kfree(cfqd->cfq_hash); +out_cfqhash: + kfree(cfqd->crq_hash); +out_crqhash: + kfree(cfqd); + return -ENOMEM; +} + +static void cfq_slab_kill(void) +{ + if (crq_pool) + kmem_cache_destroy(crq_pool); + if (cfq_pool) + kmem_cache_destroy(cfq_pool); + if (cfq_ioc_pool) + kmem_cache_destroy(cfq_ioc_pool); +} + +static int __init cfq_slab_setup(void) +{ + crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0, + NULL, NULL); + if (!crq_pool) + goto fail; + + cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0, + NULL, NULL); + if (!cfq_pool) + goto fail; + + cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool", + sizeof(struct cfq_io_context), 0, 0, NULL, NULL); + if (!cfq_ioc_pool) + goto fail; + + return 0; +fail: + cfq_slab_kill(); + return -ENOMEM; +} + +/* + * sysfs parts below --> + */ +struct cfq_fs_entry { + struct attribute attr; + ssize_t (*show)(struct cfq_data *, char *); + ssize_t (*store)(struct cfq_data *, const char *, size_t); +}; + +static ssize_t +cfq_var_show(unsigned int var, char *page) +{ + return sprintf(page, "%d\n", var); +} + +static ssize_t +cfq_var_store(unsigned int *var, const char *page, size_t count) +{ + char *p = (char *) page; + + *var = simple_strtoul(p, &p, 10); + return count; +} + +#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ +static ssize_t __FUNC(struct cfq_data *cfqd, char *page) \ +{ \ + unsigned int __data = __VAR; \ + if (__CONV) \ + __data = jiffies_to_msecs(__data); \ + return cfq_var_show(__data, (page)); \ +} +SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); +SHOW_FUNCTION(cfq_queued_show, cfqd->cfq_queued, 0); +SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); +SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); +SHOW_FUNCTION(cfq_back_max_show, cfqd->cfq_back_max, 0); +SHOW_FUNCTION(cfq_back_penalty_show, cfqd->cfq_back_penalty, 0); +SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); +SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); +SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); +SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); +SHOW_FUNCTION(cfq_max_depth_show, cfqd->cfq_max_depth, 0); +#undef SHOW_FUNCTION + +#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ +static ssize_t __FUNC(struct cfq_data *cfqd, const char *page, size_t count) \ +{ \ + unsigned int __data; \ + int ret = cfq_var_store(&__data, (page), count); \ + if (__data < (MIN)) \ + __data = (MIN); \ + else if (__data > (MAX)) \ + __data = (MAX); \ + if (__CONV) \ + *(__PTR) = msecs_to_jiffies(__data); \ + else \ + *(__PTR) = __data; \ + return ret; \ +} +STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); +STORE_FUNCTION(cfq_queued_store, &cfqd->cfq_queued, 1, UINT_MAX, 0); +STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1); +STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1); +STORE_FUNCTION(cfq_back_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); +STORE_FUNCTION(cfq_back_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0); +STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); +STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); +STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); +STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0); +STORE_FUNCTION(cfq_max_depth_store, &cfqd->cfq_max_depth, 1, UINT_MAX, 0); +#undef STORE_FUNCTION + +static struct cfq_fs_entry cfq_quantum_entry = { + .attr = {.name = "quantum", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_quantum_show, + .store = cfq_quantum_store, +}; +static struct cfq_fs_entry cfq_queued_entry = { + .attr = {.name = "queued", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_queued_show, + .store = cfq_queued_store, +}; +static struct cfq_fs_entry cfq_fifo_expire_sync_entry = { + .attr = {.name = "fifo_expire_sync", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_fifo_expire_sync_show, + .store = cfq_fifo_expire_sync_store, +}; +static struct cfq_fs_entry cfq_fifo_expire_async_entry = { + .attr = {.name = "fifo_expire_async", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_fifo_expire_async_show, + .store = cfq_fifo_expire_async_store, +}; +static struct cfq_fs_entry cfq_back_max_entry = { + .attr = {.name = "back_seek_max", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_back_max_show, + .store = cfq_back_max_store, +}; +static struct cfq_fs_entry cfq_back_penalty_entry = { + .attr = {.name = "back_seek_penalty", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_back_penalty_show, + .store = cfq_back_penalty_store, +}; +static struct cfq_fs_entry cfq_slice_sync_entry = { + .attr = {.name = "slice_sync", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_slice_sync_show, + .store = cfq_slice_sync_store, +}; +static struct cfq_fs_entry cfq_slice_async_entry = { + .attr = {.name = "slice_async", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_slice_async_show, + .store = cfq_slice_async_store, +}; +static struct cfq_fs_entry cfq_slice_async_rq_entry = { + .attr = {.name = "slice_async_rq", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_slice_async_rq_show, + .store = cfq_slice_async_rq_store, +}; +static struct cfq_fs_entry cfq_slice_idle_entry = { + .attr = {.name = "slice_idle", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_slice_idle_show, + .store = cfq_slice_idle_store, +}; +static struct cfq_fs_entry cfq_max_depth_entry = { + .attr = {.name = "max_depth", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_max_depth_show, + .store = cfq_max_depth_store, +}; + +static struct attribute *default_attrs[] = { + &cfq_quantum_entry.attr, + &cfq_queued_entry.attr, + &cfq_fifo_expire_sync_entry.attr, + &cfq_fifo_expire_async_entry.attr, + &cfq_back_max_entry.attr, + &cfq_back_penalty_entry.attr, + &cfq_slice_sync_entry.attr, + &cfq_slice_async_entry.attr, + &cfq_slice_async_rq_entry.attr, + &cfq_slice_idle_entry.attr, + &cfq_max_depth_entry.attr, + NULL, +}; + +#define to_cfq(atr) container_of((atr), struct cfq_fs_entry, attr) + +static ssize_t +cfq_attr_show(struct kobject *kobj, struct attribute *attr, char *page) +{ + elevator_t *e = container_of(kobj, elevator_t, kobj); + struct cfq_fs_entry *entry = to_cfq(attr); + + if (!entry->show) + return -EIO; + + return entry->show(e->elevator_data, page); +} + +static ssize_t +cfq_attr_store(struct kobject *kobj, struct attribute *attr, + const char *page, size_t length) +{ + elevator_t *e = container_of(kobj, elevator_t, kobj); + struct cfq_fs_entry *entry = to_cfq(attr); + + if (!entry->store) + return -EIO; + + return entry->store(e->elevator_data, page, length); +} + +static struct sysfs_ops cfq_sysfs_ops = { + .show = cfq_attr_show, + .store = cfq_attr_store, +}; + +static struct kobj_type cfq_ktype = { + .sysfs_ops = &cfq_sysfs_ops, + .default_attrs = default_attrs, +}; + +static struct elevator_type iosched_cfq = { + .ops = { + .elevator_merge_fn = cfq_merge, + .elevator_merged_fn = cfq_merged_request, + .elevator_merge_req_fn = cfq_merged_requests, + .elevator_dispatch_fn = cfq_dispatch_requests, + .elevator_add_req_fn = cfq_insert_request, + .elevator_activate_req_fn = cfq_activate_request, + .elevator_deactivate_req_fn = cfq_deactivate_request, + .elevator_queue_empty_fn = cfq_queue_empty, + .elevator_completed_req_fn = cfq_completed_request, + .elevator_former_req_fn = cfq_former_request, + .elevator_latter_req_fn = cfq_latter_request, + .elevator_set_req_fn = cfq_set_request, + .elevator_put_req_fn = cfq_put_request, + .elevator_may_queue_fn = cfq_may_queue, + .elevator_init_fn = cfq_init_queue, + .elevator_exit_fn = cfq_exit_queue, + }, + .elevator_ktype = &cfq_ktype, + .elevator_name = "cfq", + .elevator_owner = THIS_MODULE, +}; + +static int __init cfq_init(void) +{ + int ret; + + /* + * could be 0 on HZ < 1000 setups + */ + if (!cfq_slice_async) + cfq_slice_async = 1; + if (!cfq_slice_idle) + cfq_slice_idle = 1; + + if (cfq_slab_setup()) + return -ENOMEM; + + ret = elv_register(&iosched_cfq); + if (ret) + cfq_slab_kill(); + + return ret; +} + +static void __exit cfq_exit(void) +{ + elv_unregister(&iosched_cfq); + cfq_slab_kill(); +} + +module_init(cfq_init); +module_exit(cfq_exit); + +MODULE_AUTHOR("Jens Axboe"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c new file mode 100644 index 00000000000..7929471d7df --- /dev/null +++ b/block/deadline-iosched.c @@ -0,0 +1,878 @@ +/* + * linux/drivers/block/deadline-iosched.c + * + * Deadline i/o scheduler. + * + * Copyright (C) 2002 Jens Axboe <axboe@suse.de> + */ +#include <linux/kernel.h> +#include <linux/fs.h> +#include <linux/blkdev.h> +#include <linux/elevator.h> +#include <linux/bio.h> +#include <linux/config.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/compiler.h> +#include <linux/hash.h> +#include <linux/rbtree.h> + +/* + * See Documentation/block/deadline-iosched.txt + */ +static int read_expire = HZ / 2; /* max time before a read is submitted. */ +static int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */ +static int writes_starved = 2; /* max times reads can starve a write */ +static int fifo_batch = 16; /* # of sequential requests treated as one + by the above parameters. For throughput. */ + +static const int deadline_hash_shift = 5; +#define DL_HASH_BLOCK(sec) ((sec) >> 3) +#define DL_HASH_FN(sec) (hash_long(DL_HASH_BLOCK((sec)), deadline_hash_shift)) +#define DL_HASH_ENTRIES (1 << deadline_hash_shift) +#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) +#define list_entry_hash(ptr) list_entry((ptr), struct deadline_rq, hash) +#define ON_HASH(drq) (drq)->on_hash + +struct deadline_data { + /* + * run time data + */ + + /* + * requests (deadline_rq s) are present on both sort_list and fifo_list + */ + struct rb_root sort_list[2]; + struct list_head fifo_list[2]; + + /* + * next in sort order. read, write or both are NULL + */ + struct deadline_rq *next_drq[2]; + struct list_head *hash; /* request hash */ + unsigned int batching; /* number of sequential requests made */ + sector_t last_sector; /* head position */ + unsigned int starved; /* times reads have starved writes */ + + /* + * settings that change how the i/o scheduler behaves + */ + int fifo_expire[2]; + int fifo_batch; + int writes_starved; + int front_merges; + + mempool_t *drq_pool; +}; + +/* + * pre-request data. + */ +struct deadline_rq { + /* + * rbtree index, key is the starting offset + */ + struct rb_node rb_node; + sector_t rb_key; + + struct request *request; + + /* + * request hash, key is the ending offset (for back merge lookup) + */ + struct list_head hash; + char on_hash; + + /* + * expire fifo + */ + struct list_head fifo; + unsigned long expires; +}; + +static void deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq); + +static kmem_cache_t *drq_pool; + +#define RQ_DATA(rq) ((struct deadline_rq *) (rq)->elevator_private) + +/* + * the back merge hash support functions + */ +static inline void __deadline_del_drq_hash(struct deadline_rq *drq) +{ + drq->on_hash = 0; + list_del_init(&drq->hash); +} + +static inline void deadline_del_drq_hash(struct deadline_rq *drq) +{ + if (ON_HASH(drq)) + __deadline_del_drq_hash(drq); +} + +static inline void +deadline_add_drq_hash(struct deadline_data *dd, struct deadline_rq *drq) +{ + struct request *rq = drq->request; + + BUG_ON(ON_HASH(drq)); + + drq->on_hash = 1; + list_add(&drq->hash, &dd->hash[DL_HASH_FN(rq_hash_key(rq))]); +} + +/* + * move hot entry to front of chain + */ +static inline void +deadline_hot_drq_hash(struct deadline_data *dd, struct deadline_rq *drq) +{ + struct request *rq = drq->request; + struct list_head *head = &dd->hash[DL_HASH_FN(rq_hash_key(rq))]; + + if (ON_HASH(drq) && drq->hash.prev != head) { + list_del(&drq->hash); + list_add(&drq->hash, head); + } +} + +static struct request * +deadline_find_drq_hash(struct deadline_data *dd, sector_t offset) +{ + struct list_head *hash_list = &dd->hash[DL_HASH_FN(offset)]; + struct list_head *entry, *next = hash_list->next; + + while ((entry = next) != hash_list) { + struct deadline_rq *drq = list_entry_hash(entry); + struct request *__rq = drq->request; + + next = entry->next; + + BUG_ON(!ON_HASH(drq)); + + if (!rq_mergeable(__rq)) { + __deadline_del_drq_hash(drq); + continue; + } + + if (rq_hash_key(__rq) == offset) + return __rq; + } + + return NULL; +} + +/* + * rb tree support functions + */ +#define RB_NONE (2) +#define RB_EMPTY(root) ((root)->rb_node == NULL) +#define ON_RB(node) ((node)->rb_color != RB_NONE) +#define RB_CLEAR(node) ((node)->rb_color = RB_NONE) +#define rb_entry_drq(node) rb_entry((node), struct deadline_rq, rb_node) +#define DRQ_RB_ROOT(dd, drq) (&(dd)->sort_list[rq_data_dir((drq)->request)]) +#define rq_rb_key(rq) (rq)->sector + +static struct deadline_rq * +__deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq) +{ + struct rb_node **p = &DRQ_RB_ROOT(dd, drq)->rb_node; + struct rb_node *parent = NULL; + struct deadline_rq *__drq; + + while (*p) { + parent = *p; + __drq = rb_entry_drq(parent); + + if (drq->rb_key < __drq->rb_key) + p = &(*p)->rb_left; + else if (drq->rb_key > __drq->rb_key) + p = &(*p)->rb_right; + else + return __drq; + } + + rb_link_node(&drq->rb_node, parent, p); + return NULL; +} + +static void +deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq) +{ + struct deadline_rq *__alias; + + drq->rb_key = rq_rb_key(drq->request); + +retry: + __alias = __deadline_add_drq_rb(dd, drq); + if (!__alias) { + rb_insert_color(&drq->rb_node, DRQ_RB_ROOT(dd, drq)); + return; + } + + deadline_move_request(dd, __alias); + goto retry; +} + +static inline void +deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq) +{ + const int data_dir = rq_data_dir(drq->request); + + if (dd->next_drq[data_dir] == drq) { + struct rb_node *rbnext = rb_next(&drq->rb_node); + + dd->next_drq[data_dir] = NULL; + if (rbnext) + dd->next_drq[data_dir] = rb_entry_drq(rbnext); + } + + BUG_ON(!ON_RB(&drq->rb_node)); + rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq)); + RB_CLEAR(&drq->rb_node); +} + +static struct request * +deadline_find_drq_rb(struct deadline_data *dd, sector_t sector, int data_dir) +{ + struct rb_node *n = dd->sort_list[data_dir].rb_node; + struct deadline_rq *drq; + + while (n) { + drq = rb_entry_drq(n); + + if (sector < drq->rb_key) + n = n->rb_left; + else if (sector > drq->rb_key) + n = n->rb_right; + else + return drq->request; + } + + return NULL; +} + +/* + * deadline_find_first_drq finds the first (lowest sector numbered) request + * for the specified data_dir. Used to sweep back to the start of the disk + * (1-way elevator) after we process the last (highest sector) request. + */ +static struct deadline_rq * +deadline_find_first_drq(struct deadline_data *dd, int data_dir) +{ + struct rb_node *n = dd->sort_list[data_dir].rb_node; + + for (;;) { + if (n->rb_left == NULL) + return rb_entry_drq(n); + + n = n->rb_left; + } +} + +/* + * add drq to rbtree and fifo + */ +static void +deadline_add_request(struct request_queue *q, struct request *rq) +{ + struct deadline_data *dd = q->elevator->elevator_data; + struct deadline_rq *drq = RQ_DATA(rq); + + const int data_dir = rq_data_dir(drq->request); + + deadline_add_drq_rb(dd, drq); + /* + * set expire time (only used for reads) and add to fifo list + */ + drq->expires = jiffies + dd->fifo_expire[data_dir]; + list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]); + + if (rq_mergeable(rq)) + deadline_add_drq_hash(dd, drq); +} + +/* + * remove rq from rbtree, fifo, and hash + */ +static void deadline_remove_request(request_queue_t *q, struct request *rq) +{ + struct deadline_rq *drq = RQ_DATA(rq); + struct deadline_data *dd = q->elevator->elevator_data; + + list_del_init(&drq->fifo); + deadline_del_drq_rb(dd, drq); + deadline_del_drq_hash(drq); +} + +static int +deadline_merge(request_queue_t *q, struct request **req, struct bio *bio) +{ + struct deadline_data *dd = q->elevator->elevator_data; + struct request *__rq; + int ret; + + /* + * see if the merge hash can satisfy a back merge + */ + __rq = deadline_find_drq_hash(dd, bio->bi_sector); + if (__rq) { + BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector); + + if (elv_rq_merge_ok(__rq, bio)) { + ret = ELEVATOR_BACK_MERGE; + goto out; + } + } + + /* + * check for front merge + */ + if (dd->front_merges) { + sector_t rb_key = bio->bi_sector + bio_sectors(bio); + + __rq = deadline_find_drq_rb(dd, rb_key, bio_data_dir(bio)); + if (__rq) { + BUG_ON(rb_key != rq_rb_key(__rq)); + + if (elv_rq_merge_ok(__rq, bio)) { + ret = ELEVATOR_FRONT_MERGE; + goto out; + } + } + } + + return ELEVATOR_NO_MERGE; +out: + if (ret) + deadline_hot_drq_hash(dd, RQ_DATA(__rq)); + *req = __rq; + return ret; +} + +static void deadline_merged_request(request_queue_t *q, struct request *req) +{ + struct deadline_data *dd = q->elevator->elevator_data; + struct deadline_rq *drq = RQ_DATA(req); + + /* + * hash always needs to be repositioned, key is end sector + */ + deadline_del_drq_hash(drq); + deadline_add_drq_hash(dd, drq); + + /* + * if the merge was a front merge, we need to reposition request + */ + if (rq_rb_key(req) != drq->rb_key) { + deadline_del_drq_rb(dd, drq); + deadline_add_drq_rb(dd, drq); + } +} + +static void +deadline_merged_requests(request_queue_t *q, struct request *req, + struct request *next) +{ + struct deadline_data *dd = q->elevator->elevator_data; + struct deadline_rq *drq = RQ_DATA(req); + struct deadline_rq *dnext = RQ_DATA(next); + + BUG_ON(!drq); + BUG_ON(!dnext); + + /* + * reposition drq (this is the merged request) in hash, and in rbtree + * in case of a front merge + */ + deadline_del_drq_hash(drq); + deadline_add_drq_hash(dd, drq); + + if (rq_rb_key(req) != drq->rb_key) { + deadline_del_drq_rb(dd, drq); + deadline_add_drq_rb(dd, drq); + } + + /* + * if dnext expires before drq, assign its expire time to drq + * and move into dnext position (dnext will be deleted) in fifo + */ + if (!list_empty(&drq->fifo) && !list_empty(&dnext->fifo)) { + if (time_before(dnext->expires, drq->expires)) { + list_move(&drq->fifo, &dnext->fifo); + drq->expires = dnext->expires; + } + } + + /* + * kill knowledge of next, this one is a goner + */ + deadline_remove_request(q, next); +} + +/* + * move request from sort list to dispatch queue. + */ +static inline void +deadline_move_to_dispatch(struct deadline_data *dd, struct deadline_rq *drq) +{ + request_queue_t *q = drq->request->q; + + deadline_remove_request(q, drq->request); + elv_dispatch_add_tail(q, drq->request); +} + +/* + * move an entry to dispatch queue + */ +static void +deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq) +{ + const int data_dir = rq_data_dir(drq->request); + struct rb_node *rbnext = rb_next(&drq->rb_node); + + dd->next_drq[READ] = NULL; + dd->next_drq[WRITE] = NULL; + + if (rbnext) + dd->next_drq[data_dir] = rb_entry_drq(rbnext); + + dd->last_sector = drq->request->sector + drq->request->nr_sectors; + + /* + * take it off the sort and fifo list, move + * to dispatch queue + */ + deadline_move_to_dispatch(dd, drq); +} + +#define list_entry_fifo(ptr) list_entry((ptr), struct deadline_rq, fifo) + +/* + * deadline_check_fifo returns 0 if there are no expired reads on the fifo, + * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir]) + */ +static inline int deadline_check_fifo(struct deadline_data *dd, int ddir) +{ + struct deadline_rq *drq = list_entry_fifo(dd->fifo_list[ddir].next); + + /* + * drq is expired! + */ + if (time_after(jiffies, drq->expires)) + return 1; + + return 0; +} + +/* + * deadline_dispatch_requests selects the best request according to + * read/write expire, fifo_batch, etc + */ +static int deadline_dispatch_requests(request_queue_t *q, int force) +{ + struct deadline_data *dd = q->elevator->elevator_data; + const int reads = !list_empty(&dd->fifo_list[READ]); + const int writes = !list_empty(&dd->fifo_list[WRITE]); + struct deadline_rq *drq; + int data_dir; + + /* + * batches are currently reads XOR writes + */ + if (dd->next_drq[WRITE]) + drq = dd->next_drq[WRITE]; + else + drq = dd->next_drq[READ]; + + if (drq) { + /* we have a "next request" */ + + if (dd->last_sector != drq->request->sector) + /* end the batch on a non sequential request */ + dd->batching += dd->fifo_batch; + + if (dd->batching < dd->fifo_batch) + /* we are still entitled to batch */ + goto dispatch_request; + } + + /* + * at this point we are not running a batch. select the appropriate + * data direction (read / write) + */ + + if (reads) { + BUG_ON(RB_EMPTY(&dd->sort_list[READ])); + + if (writes && (dd->starved++ >= dd->writes_starved)) + goto dispatch_writes; + + data_dir = READ; + + goto dispatch_find_request; + } + + /* + * there are either no reads or writes have been starved + */ + + if (writes) { +dispatch_writes: + BUG_ON(RB_EMPTY(&dd->sort_list[WRITE])); + + dd->starved = 0; + + data_dir = WRITE; + + goto dispatch_find_request; + } + + return 0; + +dispatch_find_request: + /* + * we are not running a batch, find best request for selected data_dir + */ + if (deadline_check_fifo(dd, data_dir)) { + /* An expired request exists - satisfy it */ + dd->batching = 0; + drq = list_entry_fifo(dd->fifo_list[data_dir].next); + + } else if (dd->next_drq[data_dir]) { + /* + * The last req was the same dir and we have a next request in + * sort order. No expired requests so continue on from here. + */ + drq = dd->next_drq[data_dir]; + } else { + /* + * The last req was the other direction or we have run out of + * higher-sectored requests. Go back to the lowest sectored + * request (1 way elevator) and start a new batch. + */ + dd->batching = 0; + drq = deadline_find_first_drq(dd, data_dir); + } + +dispatch_request: + /* + * drq is the selected appropriate request. + */ + dd->batching++; + deadline_move_request(dd, drq); + + return 1; +} + +static int deadline_queue_empty(request_queue_t *q) +{ + struct deadline_data *dd = q->elevator->elevator_data; + + return list_empty(&dd->fifo_list[WRITE]) + && list_empty(&dd->fifo_list[READ]); +} + +static struct request * +deadline_former_request(request_queue_t *q, struct request *rq) +{ + struct deadline_rq *drq = RQ_DATA(rq); + struct rb_node *rbprev = rb_prev(&drq->rb_node); + + if (rbprev) + return rb_entry_drq(rbprev)->request; + + return NULL; +} + +static struct request * +deadline_latter_request(request_queue_t *q, struct request *rq) +{ + struct deadline_rq *drq = RQ_DATA(rq); + struct rb_node *rbnext = rb_next(&drq->rb_node); + + if (rbnext) + return rb_entry_drq(rbnext)->request; + + return NULL; +} + +static void deadline_exit_queue(elevator_t *e) +{ + struct deadline_data *dd = e->elevator_data; + + BUG_ON(!list_empty(&dd->fifo_list[READ])); + BUG_ON(!list_empty(&dd->fifo_list[WRITE])); + + mempool_destroy(dd->drq_pool); + kfree(dd->hash); + kfree(dd); +} + +/* + * initialize elevator private data (deadline_data), and alloc a drq for + * each request on the free lists + */ +static int deadline_init_queue(request_queue_t *q, elevator_t *e) +{ + struct deadline_data *dd; + int i; + + if (!drq_pool) + return -ENOMEM; + + dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node); + if (!dd) + return -ENOMEM; + memset(dd, 0, sizeof(*dd)); + + dd->hash = kmalloc_node(sizeof(struct list_head)*DL_HASH_ENTRIES, + GFP_KERNEL, q->node); + if (!dd->hash) { + kfree(dd); + return -ENOMEM; + } + + dd->drq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, + mempool_free_slab, drq_pool, q->node); + if (!dd->drq_pool) { + kfree(dd->hash); + kfree(dd); + return -ENOMEM; + } + + for (i = 0; i < DL_HASH_ENTRIES; i++) + INIT_LIST_HEAD(&dd->hash[i]); + + INIT_LIST_HEAD(&dd->fifo_list[READ]); + INIT_LIST_HEAD(&dd->fifo_list[WRITE]); + dd->sort_list[READ] = RB_ROOT; + dd->sort_list[WRITE] = RB_ROOT; + dd->fifo_expire[READ] = read_expire; + dd->fifo_expire[WRITE] = write_expire; + dd->writes_starved = writes_starved; + dd->front_merges = 1; + dd->fifo_batch = fifo_batch; + e->elevator_data = dd; + return 0; +} + +static void deadline_put_request(request_queue_t *q, struct request *rq) +{ + struct deadline_data *dd = q->elevator->elevator_data; + struct deadline_rq *drq = RQ_DATA(rq); + + mempool_free(drq, dd->drq_pool); + rq->elevator_private = NULL; +} + +static int +deadline_set_request(request_queue_t *q, struct request *rq, struct bio *bio, + gfp_t gfp_mask) +{ + struct deadline_data *dd = q->elevator->elevator_data; + struct deadline_rq *drq; + + drq = mempool_alloc(dd->drq_pool, gfp_mask); + if (drq) { + memset(drq, 0, sizeof(*drq)); + RB_CLEAR(&drq->rb_node); + drq->request = rq; + + INIT_LIST_HEAD(&drq->hash); + drq->on_hash = 0; + + INIT_LIST_HEAD(&drq->fifo); + + rq->elevator_private = drq; + return 0; + } + + return 1; +} + +/* + * sysfs parts below + */ +struct deadline_fs_entry { + struct attribute attr; + ssize_t (*show)(struct deadline_data *, char *); + ssize_t (*store)(struct deadline_data *, const char *, size_t); +}; + +static ssize_t +deadline_var_show(int var, char *page) +{ + return sprintf(page, "%d\n", var); +} + +static ssize_t +deadline_var_store(int *var, const char *page, size_t count) +{ + char *p = (char *) page; + + *var = simple_strtol(p, &p, 10); + return count; +} + +#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ +static ssize_t __FUNC(struct deadline_data *dd, char *page) \ +{ \ + int __data = __VAR; \ + if (__CONV) \ + __data = jiffies_to_msecs(__data); \ + return deadline_var_show(__data, (page)); \ +} +SHOW_FUNCTION(deadline_readexpire_show, dd->fifo_expire[READ], 1); +SHOW_FUNCTION(deadline_writeexpire_show, dd->fifo_expire[WRITE], 1); +SHOW_FUNCTION(deadline_writesstarved_show, dd->writes_starved, 0); +SHOW_FUNCTION(deadline_frontmerges_show, dd->front_merges, 0); +SHOW_FUNCTION(deadline_fifobatch_show, dd->fifo_batch, 0); +#undef SHOW_FUNCTION + +#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ +static ssize_t __FUNC(struct deadline_data *dd, const char *page, size_t count) \ +{ \ + int __data; \ + int ret = deadline_var_store(&__data, (page), count); \ + if (__data < (MIN)) \ + __data = (MIN); \ + else if (__data > (MAX)) \ + __data = (MAX); \ + if (__CONV) \ + *(__PTR) = msecs_to_jiffies(__data); \ + else \ + *(__PTR) = __data; \ + return ret; \ +} +STORE_FUNCTION(deadline_readexpire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1); +STORE_FUNCTION(deadline_writeexpire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1); +STORE_FUNCTION(deadline_writesstarved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0); +STORE_FUNCTION(deadline_frontmerges_store, &dd->front_merges, 0, 1, 0); +STORE_FUNCTION(deadline_fifobatch_store, &dd->fifo_batch, 0, INT_MAX, 0); +#undef STORE_FUNCTION + +static struct deadline_fs_entry deadline_readexpire_entry = { + .attr = {.name = "read_expire", .mode = S_IRUGO | S_IWUSR }, + .show = deadline_readexpire_show, + .store = deadline_readexpire_store, +}; +static struct deadline_fs_entry deadline_writeexpire_entry = { + .attr = {.name = "write_expire", .mode = S_IRUGO | S_IWUSR }, + .show = deadline_writeexpire_show, + .store = deadline_writeexpire_store, +}; +static struct deadline_fs_entry deadline_writesstarved_entry = { + .attr = {.name = "writes_starved", .mode = S_IRUGO | S_IWUSR }, + .show = deadline_writesstarved_show, + .store = deadline_writesstarved_store, +}; +static struct deadline_fs_entry deadline_frontmerges_entry = { + .attr = {.name = "front_merges", .mode = S_IRUGO | S_IWUSR }, + .show = deadline_frontmerges_show, + .store = deadline_frontmerges_store, +}; +static struct deadline_fs_entry deadline_fifobatch_entry = { + .attr = {.name = "fifo_batch", .mode = S_IRUGO | S_IWUSR }, + .show = deadline_fifobatch_show, + .store = deadline_fifobatch_store, +}; + +static struct attribute *default_attrs[] = { + &deadline_readexpire_entry.attr, + &deadline_writeexpire_entry.attr, + &deadline_writesstarved_entry.attr, + &deadline_frontmerges_entry.attr, + &deadline_fifobatch_entry.attr, + NULL, +}; + +#define to_deadline(atr) container_of((atr), struct deadline_fs_entry, attr) + +static ssize_t +deadline_attr_show(struct kobject *kobj, struct attribute *attr, char *page) +{ + elevator_t *e = container_of(kobj, elevator_t, kobj); + struct deadline_fs_entry *entry = to_deadline(attr); + + if (!entry->show) + return -EIO; + + return entry->show(e->elevator_data, page); +} + +static ssize_t +deadline_attr_store(struct kobject *kobj, struct attribute *attr, + const char *page, size_t length) +{ + elevator_t *e = container_of(kobj, elevator_t, kobj); + struct deadline_fs_entry *entry = to_deadline(attr); + + if (!entry->store) + return -EIO; + + return entry->store(e->elevator_data, page, length); +} + +static struct sysfs_ops deadline_sysfs_ops = { + .show = deadline_attr_show, + .store = deadline_attr_store, +}; + +static struct kobj_type deadline_ktype = { + .sysfs_ops = &deadline_sysfs_ops, + .default_attrs = default_attrs, +}; + +static struct elevator_type iosched_deadline = { + .ops = { + .elevator_merge_fn = deadline_merge, + .elevator_merged_fn = deadline_merged_request, + .elevator_merge_req_fn = deadline_merged_requests, + .elevator_dispatch_fn = deadline_dispatch_requests, + .elevator_add_req_fn = deadline_add_request, + .elevator_queue_empty_fn = deadline_queue_empty, + .elevator_former_req_fn = deadline_former_request, + .elevator_latter_req_fn = deadline_latter_request, + .elevator_set_req_fn = deadline_set_request, + .elevator_put_req_fn = deadline_put_request, + .elevator_init_fn = deadline_init_queue, + .elevator_exit_fn = deadline_exit_queue, + }, + + .elevator_ktype = &deadline_ktype, + .elevator_name = "deadline", + .elevator_owner = THIS_MODULE, +}; + +static int __init deadline_init(void) +{ + int ret; + + drq_pool = kmem_cache_create("deadline_drq", sizeof(struct deadline_rq), + 0, 0, NULL, NULL); + + if (!drq_pool) + return -ENOMEM; + + ret = elv_register(&iosched_deadline); + if (ret) + kmem_cache_destroy(drq_pool); + + return ret; +} + +static void __exit deadline_exit(void) +{ + kmem_cache_destroy(drq_pool); + elv_unregister(&iosched_deadline); +} + +module_init(deadline_init); +module_exit(deadline_exit); + +MODULE_AUTHOR("Jens Axboe"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("deadline IO scheduler"); diff --git a/block/elevator.c b/block/elevator.c new file mode 100644 index 00000000000..d4a49a3df82 --- /dev/null +++ b/block/elevator.c @@ -0,0 +1,802 @@ +/* + * linux/drivers/block/elevator.c + * + * Block device elevator/IO-scheduler. + * + * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE + * + * 30042000 Jens Axboe <axboe@suse.de> : + * + * Split the elevator a bit so that it is possible to choose a different + * one or even write a new "plug in". There are three pieces: + * - elevator_fn, inserts a new request in the queue list + * - elevator_merge_fn, decides whether a new buffer can be merged with + * an existing request + * - elevator_dequeue_fn, called when a request is taken off the active list + * + * 20082000 Dave Jones <davej@suse.de> : + * Removed tests for max-bomb-segments, which was breaking elvtune + * when run without -bN + * + * Jens: + * - Rework again to work with bio instead of buffer_heads + * - loose bi_dev comparisons, partition handling is right now + * - completely modularize elevator setup and teardown + * + */ +#include <linux/kernel.h> +#include <linux/fs.h> +#include <linux/blkdev.h> +#include <linux/elevator.h> +#include <linux/bio.h> +#include <linux/config.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/compiler.h> +#include <linux/delay.h> + +#include <asm/uaccess.h> + +static DEFINE_SPINLOCK(elv_list_lock); +static LIST_HEAD(elv_list); + +/* + * can we safely merge with this request? + */ +inline int elv_rq_merge_ok(struct request *rq, struct bio *bio) +{ + if (!rq_mergeable(rq)) + return 0; + + /* + * different data direction or already started, don't merge + */ + if (bio_data_dir(bio) != rq_data_dir(rq)) + return 0; + + /* + * same device and no special stuff set, merge is ok + */ + if (rq->rq_disk == bio->bi_bdev->bd_disk && + !rq->waiting && !rq->special) + return 1; + + return 0; +} +EXPORT_SYMBOL(elv_rq_merge_ok); + +inline int elv_try_merge(struct request *__rq, struct bio *bio) +{ + int ret = ELEVATOR_NO_MERGE; + + /* + * we can merge and sequence is ok, check if it's possible + */ + if (elv_rq_merge_ok(__rq, bio)) { + if (__rq->sector + __rq->nr_sectors == bio->bi_sector) + ret = ELEVATOR_BACK_MERGE; + else if (__rq->sector - bio_sectors(bio) == bio->bi_sector) + ret = ELEVATOR_FRONT_MERGE; + } + + return ret; +} +EXPORT_SYMBOL(elv_try_merge); + +static struct elevator_type *elevator_find(const char *name) +{ + struct elevator_type *e = NULL; + struct list_head *entry; + + list_for_each(entry, &elv_list) { + struct elevator_type *__e; + + __e = list_entry(entry, struct elevator_type, list); + + if (!strcmp(__e->elevator_name, name)) { + e = __e; + break; + } + } + + return e; +} + +static void elevator_put(struct elevator_type *e) +{ + module_put(e->elevator_owner); +} + +static struct elevator_type *elevator_get(const char *name) +{ + struct elevator_type *e; + + spin_lock_irq(&elv_list_lock); + + e = elevator_find(name); + if (e && !try_module_get(e->elevator_owner)) + e = NULL; + + spin_unlock_irq(&elv_list_lock); + + return e; +} + +static int elevator_attach(request_queue_t *q, struct elevator_type *e, + struct elevator_queue *eq) +{ + int ret = 0; + + memset(eq, 0, sizeof(*eq)); + eq->ops = &e->ops; + eq->elevator_type = e; + + q->elevator = eq; + + if (eq->ops->elevator_init_fn) + ret = eq->ops->elevator_init_fn(q, eq); + + return ret; +} + +static char chosen_elevator[16]; + +static void elevator_setup_default(void) +{ + struct elevator_type *e; + + /* + * If default has not been set, use the compiled-in selection. + */ + if (!chosen_elevator[0]) + strcpy(chosen_elevator, CONFIG_DEFAULT_IOSCHED); + + /* + * If the given scheduler is not available, fall back to no-op. + */ + if (!(e = elevator_find(chosen_elevator))) + strcpy(chosen_elevator, "noop"); + elevator_put(e); +} + +static int __init elevator_setup(char *str) +{ + strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); + return 0; +} + +__setup("elevator=", elevator_setup); + +int elevator_init(request_queue_t *q, char *name) +{ + struct elevator_type *e = NULL; + struct elevator_queue *eq; + int ret = 0; + + INIT_LIST_HEAD(&q->queue_head); + q->last_merge = NULL; + q->end_sector = 0; + q->boundary_rq = NULL; + + elevator_setup_default(); + + if (!name) + name = chosen_elevator; + + e = elevator_get(name); + if (!e) + return -EINVAL; + + eq = kmalloc(sizeof(struct elevator_queue), GFP_KERNEL); + if (!eq) { + elevator_put(e->elevator_type); + return -ENOMEM; + } + + ret = elevator_attach(q, e, eq); + if (ret) { + kfree(eq); + elevator_put(e->elevator_type); + } + + return ret; +} + +void elevator_exit(elevator_t *e) +{ + if (e->ops->elevator_exit_fn) + e->ops->elevator_exit_fn(e); + + elevator_put(e->elevator_type); + e->elevator_type = NULL; + kfree(e); +} + +/* + * Insert rq into dispatch queue of q. Queue lock must be held on + * entry. If sort != 0, rq is sort-inserted; otherwise, rq will be + * appended to the dispatch queue. To be used by specific elevators. + */ +void elv_dispatch_sort(request_queue_t *q, struct request *rq) +{ + sector_t boundary; + struct list_head *entry; + + if (q->last_merge == rq) + q->last_merge = NULL; + + boundary = q->end_sector; + + list_for_each_prev(entry, &q->queue_head) { + struct request *pos = list_entry_rq(entry); + + if (pos->flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED)) + break; + if (rq->sector >= boundary) { + if (pos->sector < boundary) + continue; + } else { + if (pos->sector >= boundary) + break; + } + if (rq->sector >= pos->sector) + break; + } + + list_add(&rq->queuelist, entry); +} + +int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) +{ + elevator_t *e = q->elevator; + int ret; + + if (q->last_merge) { + ret = elv_try_merge(q->last_merge, bio); + if (ret != ELEVATOR_NO_MERGE) { + *req = q->last_merge; + return ret; + } + } + + if (e->ops->elevator_merge_fn) + return e->ops->elevator_merge_fn(q, req, bio); + + return ELEVATOR_NO_MERGE; +} + +void elv_merged_request(request_queue_t *q, struct request *rq) +{ + elevator_t *e = q->elevator; + + if (e->ops->elevator_merged_fn) + e->ops->elevator_merged_fn(q, rq); + + q->last_merge = rq; +} + +void elv_merge_requests(request_queue_t *q, struct request *rq, + struct request *next) +{ + elevator_t *e = q->elevator; + + if (e->ops->elevator_merge_req_fn) + e->ops->elevator_merge_req_fn(q, rq, next); + + q->last_merge = rq; +} + +void elv_requeue_request(request_queue_t *q, struct request *rq) +{ + elevator_t *e = q->elevator; + + /* + * it already went through dequeue, we need to decrement the + * in_flight count again + */ + if (blk_account_rq(rq)) { + q->in_flight--; + if (blk_sorted_rq(rq) && e->ops->elevator_deactivate_req_fn) + e->ops->elevator_deactivate_req_fn(q, rq); + } + + rq->flags &= ~REQ_STARTED; + + /* + * if this is the flush, requeue the original instead and drop the flush + */ + if (rq->flags & REQ_BAR_FLUSH) { + clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags); + rq = rq->end_io_data; + } + + __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0); +} + +void __elv_add_request(request_queue_t *q, struct request *rq, int where, + int plug) +{ + if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { + /* + * barriers implicitly indicate back insertion + */ + if (where == ELEVATOR_INSERT_SORT) + where = ELEVATOR_INSERT_BACK; + + /* + * this request is scheduling boundary, update end_sector + */ + if (blk_fs_request(rq)) { + q->end_sector = rq_end_sector(rq); + q->boundary_rq = rq; + } + } else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT) + where = ELEVATOR_INSERT_BACK; + + if (plug) + blk_plug_device(q); + + rq->q = q; + + switch (where) { + case ELEVATOR_INSERT_FRONT: + rq->flags |= REQ_SOFTBARRIER; + + list_add(&rq->queuelist, &q->queue_head); + break; + + case ELEVATOR_INSERT_BACK: + rq->flags |= REQ_SOFTBARRIER; + + while (q->elevator->ops->elevator_dispatch_fn(q, 1)) + ; + list_add_tail(&rq->queuelist, &q->queue_head); + /* + * We kick the queue here for the following reasons. + * - The elevator might have returned NULL previously + * to delay requests and returned them now. As the + * queue wasn't empty before this request, ll_rw_blk + * won't run the queue on return, resulting in hang. + * - Usually, back inserted requests won't be merged + * with anything. There's no point in delaying queue + * processing. + */ + blk_remove_plug(q); + q->request_fn(q); + break; + + case ELEVATOR_INSERT_SORT: + BUG_ON(!blk_fs_request(rq)); + rq->flags |= REQ_SORTED; + if (q->last_merge == NULL && rq_mergeable(rq)) + q->last_merge = rq; + /* + * Some ioscheds (cfq) run q->request_fn directly, so + * rq cannot be accessed after calling + * elevator_add_req_fn. + */ + q->elevator->ops->elevator_add_req_fn(q, rq); + break; + + default: + printk(KERN_ERR "%s: bad insertion point %d\n", + __FUNCTION__, where); + BUG(); + } + + if (blk_queue_plugged(q)) { + int nrq = q->rq.count[READ] + q->rq.count[WRITE] + - q->in_flight; + + if (nrq >= q->unplug_thresh) + __generic_unplug_device(q); + } +} + +void elv_add_request(request_queue_t *q, struct request *rq, int where, + int plug) +{ + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + __elv_add_request(q, rq, where, plug); + spin_unlock_irqrestore(q->queue_lock, flags); +} + +static inline struct request *__elv_next_request(request_queue_t *q) +{ + struct request *rq; + + if (unlikely(list_empty(&q->queue_head) && + !q->elevator->ops->elevator_dispatch_fn(q, 0))) + return NULL; + + rq = list_entry_rq(q->queue_head.next); + + /* + * if this is a barrier write and the device has to issue a + * flush sequence to support it, check how far we are + */ + if (blk_fs_request(rq) && blk_barrier_rq(rq)) { + BUG_ON(q->ordered == QUEUE_ORDERED_NONE); + + if (q->ordered == QUEUE_ORDERED_FLUSH && + !blk_barrier_preflush(rq)) + rq = blk_start_pre_flush(q, rq); + } + + return rq; +} + +struct request *elv_next_request(request_queue_t *q) +{ + struct request *rq; + int ret; + + while ((rq = __elv_next_request(q)) != NULL) { + if (!(rq->flags & REQ_STARTED)) { + elevator_t *e = q->elevator; + + /* + * This is the first time the device driver + * sees this request (possibly after + * requeueing). Notify IO scheduler. + */ + if (blk_sorted_rq(rq) && + e->ops->elevator_activate_req_fn) + e->ops->elevator_activate_req_fn(q, rq); + + /* + * just mark as started even if we don't start + * it, a request that has been delayed should + * not be passed by new incoming requests + */ + rq->flags |= REQ_STARTED; + } + + if (!q->boundary_rq || q->boundary_rq == rq) { + q->end_sector = rq_end_sector(rq); + q->boundary_rq = NULL; + } + + if ((rq->flags & REQ_DONTPREP) || !q->prep_rq_fn) + break; + + ret = q->prep_rq_fn(q, rq); + if (ret == BLKPREP_OK) { + break; + } else if (ret == BLKPREP_DEFER) { + /* + * the request may have been (partially) prepped. + * we need to keep this request in the front to + * avoid resource deadlock. REQ_STARTED will + * prevent other fs requests from passing this one. + */ + rq = NULL; + break; + } else if (ret == BLKPREP_KILL) { + int nr_bytes = rq->hard_nr_sectors << 9; + + if (!nr_bytes) + nr_bytes = rq->data_len; + + blkdev_dequeue_request(rq); + rq->flags |= REQ_QUIET; + end_that_request_chunk(rq, 0, nr_bytes); + end_that_request_last(rq); + } else { + printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, + ret); + break; + } + } + + return rq; +} + +void elv_dequeue_request(request_queue_t *q, struct request *rq) +{ + BUG_ON(list_empty(&rq->queuelist)); + + list_del_init(&rq->queuelist); + + /* + * the time frame between a request being removed from the lists + * and to it is freed is accounted as io that is in progress at + * the driver side. + */ + if (blk_account_rq(rq)) + q->in_flight++; +} + +int elv_queue_empty(request_queue_t *q) +{ + elevator_t *e = q->elevator; + + if (!list_empty(&q->queue_head)) + return 0; + + if (e->ops->elevator_queue_empty_fn) + return e->ops->elevator_queue_empty_fn(q); + + return 1; +} + +struct request *elv_latter_request(request_queue_t *q, struct request *rq) +{ + struct list_head *next; + + elevator_t *e = q->elevator; + + if (e->ops->elevator_latter_req_fn) + return e->ops->elevator_latter_req_fn(q, rq); + + next = rq->queuelist.next; + if (next != &q->queue_head && next != &rq->queuelist) + return list_entry_rq(next); + + return NULL; +} + +struct request *elv_former_request(request_queue_t *q, struct request *rq) +{ + struct list_head *prev; + + elevator_t *e = q->elevator; + + if (e->ops->elevator_former_req_fn) + return e->ops->elevator_former_req_fn(q, rq); + + prev = rq->queuelist.prev; + if (prev != &q->queue_head && prev != &rq->queuelist) + return list_entry_rq(prev); + + return NULL; +} + +int elv_set_request(request_queue_t *q, struct request *rq, struct bio *bio, + gfp_t gfp_mask) +{ + elevator_t *e = q->elevator; + + if (e->ops->elevator_set_req_fn) + return e->ops->elevator_set_req_fn(q, rq, bio, gfp_mask); + + rq->elevator_private = NULL; + return 0; +} + +void elv_put_request(request_queue_t *q, struct request *rq) +{ + elevator_t *e = q->elevator; + + if (e->ops->elevator_put_req_fn) + e->ops->elevator_put_req_fn(q, rq); +} + +int elv_may_queue(request_queue_t *q, int rw, struct bio *bio) +{ + elevator_t *e = q->elevator; + + if (e->ops->elevator_may_queue_fn) + return e->ops->elevator_may_queue_fn(q, rw, bio); + + return ELV_MQUEUE_MAY; +} + +void elv_completed_request(request_queue_t *q, struct request *rq) +{ + elevator_t *e = q->elevator; + + /* + * request is released from the driver, io must be done + */ + if (blk_account_rq(rq)) { + q->in_flight--; + if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) + e->ops->elevator_completed_req_fn(q, rq); + } +} + +int elv_register_queue(struct request_queue *q) +{ + elevator_t *e = q->elevator; + + e->kobj.parent = kobject_get(&q->kobj); + if (!e->kobj.parent) + return -EBUSY; + + snprintf(e->kobj.name, KOBJ_NAME_LEN, "%s", "iosched"); + e->kobj.ktype = e->elevator_type->elevator_ktype; + + return kobject_register(&e->kobj); +} + +void elv_unregister_queue(struct request_queue *q) +{ + if (q) { + elevator_t *e = q->elevator; + kobject_unregister(&e->kobj); + kobject_put(&q->kobj); + } +} + +int elv_register(struct elevator_type *e) +{ + spin_lock_irq(&elv_list_lock); + if (elevator_find(e->elevator_name)) + BUG(); + list_add_tail(&e->list, &elv_list); + spin_unlock_irq(&elv_list_lock); + + printk(KERN_INFO "io scheduler %s registered", e->elevator_name); + if (!strcmp(e->elevator_name, chosen_elevator)) + printk(" (default)"); + printk("\n"); + return 0; +} +EXPORT_SYMBOL_GPL(elv_register); + +void elv_unregister(struct elevator_type *e) +{ + struct task_struct *g, *p; + + /* + * Iterate every thread in the process to remove the io contexts. + */ + read_lock(&tasklist_lock); + do_each_thread(g, p) { + struct io_context *ioc = p->io_context; + if (ioc && ioc->cic) { + ioc->cic->exit(ioc->cic); + ioc->cic->dtor(ioc->cic); + ioc->cic = NULL; + } + if (ioc && ioc->aic) { + ioc->aic->exit(ioc->aic); + ioc->aic->dtor(ioc->aic); + ioc->aic = NULL; + } + } while_each_thread(g, p); + read_unlock(&tasklist_lock); + + spin_lock_irq(&elv_list_lock); + list_del_init(&e->list); + spin_unlock_irq(&elv_list_lock); +} +EXPORT_SYMBOL_GPL(elv_unregister); + +/* + * switch to new_e io scheduler. be careful not to introduce deadlocks - + * we don't free the old io scheduler, before we have allocated what we + * need for the new one. this way we have a chance of going back to the old + * one, if the new one fails init for some reason. + */ +static void elevator_switch(request_queue_t *q, struct elevator_type *new_e) +{ + elevator_t *old_elevator, *e; + + /* + * Allocate new elevator + */ + e = kmalloc(sizeof(elevator_t), GFP_KERNEL); + if (!e) + goto error; + + /* + * Turn on BYPASS and drain all requests w/ elevator private data + */ + spin_lock_irq(q->queue_lock); + + set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); + + while (q->elevator->ops->elevator_dispatch_fn(q, 1)) + ; + + while (q->rq.elvpriv) { + spin_unlock_irq(q->queue_lock); + msleep(10); + spin_lock_irq(q->queue_lock); + } + + spin_unlock_irq(q->queue_lock); + + /* + * unregister old elevator data + */ + elv_unregister_queue(q); + old_elevator = q->elevator; + + /* + * attach and start new elevator + */ + if (elevator_attach(q, new_e, e)) + goto fail; + + if (elv_register_queue(q)) + goto fail_register; + + /* + * finally exit old elevator and turn off BYPASS. + */ + elevator_exit(old_elevator); + clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); + return; + +fail_register: + /* + * switch failed, exit the new io scheduler and reattach the old + * one again (along with re-adding the sysfs dir) + */ + elevator_exit(e); + e = NULL; +fail: + q->elevator = old_elevator; + elv_register_queue(q); + clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); + kfree(e); +error: + elevator_put(new_e); + printk(KERN_ERR "elevator: switch to %s failed\n",new_e->elevator_name); +} + +ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count) +{ + char elevator_name[ELV_NAME_MAX]; + struct elevator_type *e; + + memset(elevator_name, 0, sizeof(elevator_name)); + strncpy(elevator_name, name, sizeof(elevator_name)); + + if (elevator_name[strlen(elevator_name) - 1] == '\n') + elevator_name[strlen(elevator_name) - 1] = '\0'; + + e = elevator_get(elevator_name); + if (!e) { + printk(KERN_ERR "elevator: type %s not found\n", elevator_name); + return -EINVAL; + } + + if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { + elevator_put(e); + return count; + } + + elevator_switch(q, e); + return count; +} + +ssize_t elv_iosched_show(request_queue_t *q, char *name) +{ + elevator_t *e = q->elevator; + struct elevator_type *elv = e->elevator_type; + struct list_head *entry; + int len = 0; + + spin_lock_irq(q->queue_lock); + list_for_each(entry, &elv_list) { + struct elevator_type *__e; + + __e = list_entry(entry, struct elevator_type, list); + if (!strcmp(elv->elevator_name, __e->elevator_name)) + len += sprintf(name+len, "[%s] ", elv->elevator_name); + else + len += sprintf(name+len, "%s ", __e->elevator_name); + } + spin_unlock_irq(q->queue_lock); + + len += sprintf(len+name, "\n"); + return len; +} + +EXPORT_SYMBOL(elv_dispatch_sort); +EXPORT_SYMBOL(elv_add_request); +EXPORT_SYMBOL(__elv_add_request); +EXPORT_SYMBOL(elv_requeue_request); +EXPORT_SYMBOL(elv_next_request); +EXPORT_SYMBOL(elv_dequeue_request); +EXPORT_SYMBOL(elv_queue_empty); +EXPORT_SYMBOL(elv_completed_request); +EXPORT_SYMBOL(elevator_exit); +EXPORT_SYMBOL(elevator_init); diff --git a/block/genhd.c b/block/genhd.c new file mode 100644 index 00000000000..54aec4a1ae1 --- /dev/null +++ b/block/genhd.c @@ -0,0 +1,726 @@ +/* + * gendisk handling + */ + +#include <linux/config.h> +#include <linux/module.h> +#include <linux/fs.h> +#include <linux/genhd.h> +#include <linux/kernel.h> +#include <linux/blkdev.h> +#include <linux/init.h> +#include <linux/spinlock.h> +#include <linux/seq_file.h> +#include <linux/slab.h> +#include <linux/kmod.h> +#include <linux/kobj_map.h> +#include <linux/buffer_head.h> + +#define MAX_PROBE_HASH 255 /* random */ + +static struct subsystem block_subsys; + +static DECLARE_MUTEX(block_subsys_sem); + +/* + * Can be deleted altogether. Later. + * + */ +static struct blk_major_name { + struct blk_major_name *next; + int major; + char name[16]; +} *major_names[MAX_PROBE_HASH]; + +/* index in the above - for now: assume no multimajor ranges */ +static inline int major_to_index(int major) +{ + return major % MAX_PROBE_HASH; +} + +#ifdef CONFIG_PROC_FS +/* get block device names in somewhat random order */ +int get_blkdev_list(char *p, int used) +{ + struct blk_major_name *n; + int i, len; + + len = snprintf(p, (PAGE_SIZE-used), "\nBlock devices:\n"); + + down(&block_subsys_sem); + for (i = 0; i < ARRAY_SIZE(major_names); i++) { + for (n = major_names[i]; n; n = n->next) { + /* + * If the curent string plus the 5 extra characters + * in the line would run us off the page, then we're done + */ + if ((len + used + strlen(n->name) + 5) >= PAGE_SIZE) + goto page_full; + len += sprintf(p+len, "%3d %s\n", + n->major, n->name); + } + } +page_full: + up(&block_subsys_sem); + + return len; +} +#endif + +int register_blkdev(unsigned int major, const char *name) +{ + struct blk_major_name **n, *p; + int index, ret = 0; + + down(&block_subsys_sem); + + /* temporary */ + if (major == 0) { + for (index = ARRAY_SIZE(major_names)-1; index > 0; index--) { + if (major_names[index] == NULL) + break; + } + + if (index == 0) { + printk("register_blkdev: failed to get major for %s\n", + name); + ret = -EBUSY; + goto out; + } + major = index; + ret = major; + } + + p = kmalloc(sizeof(struct blk_major_name), GFP_KERNEL); + if (p == NULL) { + ret = -ENOMEM; + goto out; + } + + p->major = major; + strlcpy(p->name, name, sizeof(p->name)); + p->next = NULL; + index = major_to_index(major); + + for (n = &major_names[index]; *n; n = &(*n)->next) { + if ((*n)->major == major) + break; + } + if (!*n) + *n = p; + else + ret = -EBUSY; + + if (ret < 0) { + printk("register_blkdev: cannot get major %d for %s\n", + major, name); + kfree(p); + } +out: + up(&block_subsys_sem); + return ret; +} + +EXPORT_SYMBOL(register_blkdev); + +/* todo: make void - error printk here */ +int unregister_blkdev(unsigned int major, const char *name) +{ + struct blk_major_name **n; + struct blk_major_name *p = NULL; + int index = major_to_index(major); + int ret = 0; + + down(&block_subsys_sem); + for (n = &major_names[index]; *n; n = &(*n)->next) + if ((*n)->major == major) + break; + if (!*n || strcmp((*n)->name, name)) + ret = -EINVAL; + else { + p = *n; + *n = p->next; + } + up(&block_subsys_sem); + kfree(p); + + return ret; +} + +EXPORT_SYMBOL(unregister_blkdev); + +static struct kobj_map *bdev_map; + +/* + * Register device numbers dev..(dev+range-1) + * range must be nonzero + * The hash chain is sorted on range, so that subranges can override. + */ +void blk_register_region(dev_t dev, unsigned long range, struct module *module, + struct kobject *(*probe)(dev_t, int *, void *), + int (*lock)(dev_t, void *), void *data) +{ + kobj_map(bdev_map, dev, range, module, probe, lock, data); +} + +EXPORT_SYMBOL(blk_register_region); + +void blk_unregister_region(dev_t dev, unsigned long range) +{ + kobj_unmap(bdev_map, dev, range); +} + +EXPORT_SYMBOL(blk_unregister_region); + +static struct kobject *exact_match(dev_t dev, int *part, void *data) +{ + struct gendisk *p = data; + return &p->kobj; +} + +static int exact_lock(dev_t dev, void *data) +{ + struct gendisk *p = data; + + if (!get_disk(p)) + return -1; + return 0; +} + +/** + * add_disk - add partitioning information to kernel list + * @disk: per-device partitioning information + * + * This function registers the partitioning information in @disk + * with the kernel. + */ +void add_disk(struct gendisk *disk) +{ + disk->flags |= GENHD_FL_UP; + blk_register_region(MKDEV(disk->major, disk->first_minor), + disk->minors, NULL, exact_match, exact_lock, disk); + register_disk(disk); + blk_register_queue(disk); +} + +EXPORT_SYMBOL(add_disk); +EXPORT_SYMBOL(del_gendisk); /* in partitions/check.c */ + +void unlink_gendisk(struct gendisk *disk) +{ + blk_unregister_queue(disk); + blk_unregister_region(MKDEV(disk->major, disk->first_minor), + disk->minors); +} + +#define to_disk(obj) container_of(obj,struct gendisk,kobj) + +/** + * get_gendisk - get partitioning information for a given device + * @dev: device to get partitioning information for + * + * This function gets the structure containing partitioning + * information for the given device @dev. + */ +struct gendisk *get_gendisk(dev_t dev, int *part) +{ + struct kobject *kobj = kobj_lookup(bdev_map, dev, part); + return kobj ? to_disk(kobj) : NULL; +} + +#ifdef CONFIG_PROC_FS +/* iterator */ +static void *part_start(struct seq_file *part, loff_t *pos) +{ + struct list_head *p; + loff_t l = *pos; + + down(&block_subsys_sem); + list_for_each(p, &block_subsys.kset.list) + if (!l--) + return list_entry(p, struct gendisk, kobj.entry); + return NULL; +} + +static void *part_next(struct seq_file *part, void *v, loff_t *pos) +{ + struct list_head *p = ((struct gendisk *)v)->kobj.entry.next; + ++*pos; + return p==&block_subsys.kset.list ? NULL : + list_entry(p, struct gendisk, kobj.entry); +} + +static void part_stop(struct seq_file *part, void *v) +{ + up(&block_subsys_sem); +} + +static int show_partition(struct seq_file *part, void *v) +{ + struct gendisk *sgp = v; + int n; + char buf[BDEVNAME_SIZE]; + + if (&sgp->kobj.entry == block_subsys.kset.list.next) + seq_puts(part, "major minor #blocks name\n\n"); + + /* Don't show non-partitionable removeable devices or empty devices */ + if (!get_capacity(sgp) || + (sgp->minors == 1 && (sgp->flags & GENHD_FL_REMOVABLE))) + return 0; + if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO) + return 0; + + /* show the full disk and all non-0 size partitions of it */ + seq_printf(part, "%4d %4d %10llu %s\n", + sgp->major, sgp->first_minor, + (unsigned long long)get_capacity(sgp) >> 1, + disk_name(sgp, 0, buf)); + for (n = 0; n < sgp->minors - 1; n++) { + if (!sgp->part[n]) + continue; + if (sgp->part[n]->nr_sects == 0) + continue; + seq_printf(part, "%4d %4d %10llu %s\n", + sgp->major, n + 1 + sgp->first_minor, + (unsigned long long)sgp->part[n]->nr_sects >> 1 , + disk_name(sgp, n + 1, buf)); + } + + return 0; +} + +struct seq_operations partitions_op = { + .start =part_start, + .next = part_next, + .stop = part_stop, + .show = show_partition +}; +#endif + + +extern int blk_dev_init(void); + +static struct kobject *base_probe(dev_t dev, int *part, void *data) +{ + if (request_module("block-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0) + /* Make old-style 2.4 aliases work */ + request_module("block-major-%d", MAJOR(dev)); + return NULL; +} + +static int __init genhd_device_init(void) +{ + bdev_map = kobj_map_init(base_probe, &block_subsys_sem); + blk_dev_init(); + subsystem_register(&block_subsys); + return 0; +} + +subsys_initcall(genhd_device_init); + + + +/* + * kobject & sysfs bindings for block devices + */ +static ssize_t disk_attr_show(struct kobject *kobj, struct attribute *attr, + char *page) +{ + struct gendisk *disk = to_disk(kobj); + struct disk_attribute *disk_attr = + container_of(attr,struct disk_attribute,attr); + ssize_t ret = -EIO; + + if (disk_attr->show) + ret = disk_attr->show(disk,page); + return ret; +} + +static ssize_t disk_attr_store(struct kobject * kobj, struct attribute * attr, + const char *page, size_t count) +{ + struct gendisk *disk = to_disk(kobj); + struct disk_attribute *disk_attr = + container_of(attr,struct disk_attribute,attr); + ssize_t ret = 0; + + if (disk_attr->store) + ret = disk_attr->store(disk, page, count); + return ret; +} + +static struct sysfs_ops disk_sysfs_ops = { + .show = &disk_attr_show, + .store = &disk_attr_store, +}; + +static ssize_t disk_uevent_store(struct gendisk * disk, + const char *buf, size_t count) +{ + kobject_hotplug(&disk->kobj, KOBJ_ADD); + return count; +} +static ssize_t disk_dev_read(struct gendisk * disk, char *page) +{ + dev_t base = MKDEV(disk->major, disk->first_minor); + return print_dev_t(page, base); +} +static ssize_t disk_range_read(struct gendisk * disk, char *page) +{ + return sprintf(page, "%d\n", disk->minors); +} +static ssize_t disk_removable_read(struct gendisk * disk, char *page) +{ + return sprintf(page, "%d\n", + (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0)); + +} +static ssize_t disk_size_read(struct gendisk * disk, char *page) +{ + return sprintf(page, "%llu\n", (unsigned long long)get_capacity(disk)); +} + +static ssize_t disk_stats_read(struct gendisk * disk, char *page) +{ + preempt_disable(); + disk_round_stats(disk); + preempt_enable(); + return sprintf(page, + "%8u %8u %8llu %8u " + "%8u %8u %8llu %8u " + "%8u %8u %8u" + "\n", + disk_stat_read(disk, ios[0]), disk_stat_read(disk, merges[0]), + (unsigned long long)disk_stat_read(disk, sectors[0]), + jiffies_to_msecs(disk_stat_read(disk, ticks[0])), + disk_stat_read(disk, ios[1]), disk_stat_read(disk, merges[1]), + (unsigned long long)disk_stat_read(disk, sectors[1]), + jiffies_to_msecs(disk_stat_read(disk, ticks[1])), + disk->in_flight, + jiffies_to_msecs(disk_stat_read(disk, io_ticks)), + jiffies_to_msecs(disk_stat_read(disk, time_in_queue))); +} +static struct disk_attribute disk_attr_uevent = { + .attr = {.name = "uevent", .mode = S_IWUSR }, + .store = disk_uevent_store +}; +static struct disk_attribute disk_attr_dev = { + .attr = {.name = "dev", .mode = S_IRUGO }, + .show = disk_dev_read +}; +static struct disk_attribute disk_attr_range = { + .attr = {.name = "range", .mode = S_IRUGO }, + .show = disk_range_read +}; +static struct disk_attribute disk_attr_removable = { + .attr = {.name = "removable", .mode = S_IRUGO }, + .show = disk_removable_read +}; +static struct disk_attribute disk_attr_size = { + .attr = {.name = "size", .mode = S_IRUGO }, + .show = disk_size_read +}; +static struct disk_attribute disk_attr_stat = { + .attr = {.name = "stat", .mode = S_IRUGO }, + .show = disk_stats_read +}; + +static struct attribute * default_attrs[] = { + &disk_attr_uevent.attr, + &disk_attr_dev.attr, + &disk_attr_range.attr, + &disk_attr_removable.attr, + &disk_attr_size.attr, + &disk_attr_stat.attr, + NULL, +}; + +static void disk_release(struct kobject * kobj) +{ + struct gendisk *disk = to_disk(kobj); + kfree(disk->random); + kfree(disk->part); + free_disk_stats(disk); + kfree(disk); +} + +static struct kobj_type ktype_block = { + .release = disk_release, + .sysfs_ops = &disk_sysfs_ops, + .default_attrs = default_attrs, +}; + +extern struct kobj_type ktype_part; + +static int block_hotplug_filter(struct kset *kset, struct kobject *kobj) +{ + struct kobj_type *ktype = get_ktype(kobj); + + return ((ktype == &ktype_block) || (ktype == &ktype_part)); +} + +static int block_hotplug(struct kset *kset, struct kobject *kobj, char **envp, + int num_envp, char *buffer, int buffer_size) +{ + struct kobj_type *ktype = get_ktype(kobj); + struct device *physdev; + struct gendisk *disk; + struct hd_struct *part; + int length = 0; + int i = 0; + + if (ktype == &ktype_block) { + disk = container_of(kobj, struct gendisk, kobj); + add_hotplug_env_var(envp, num_envp, &i, buffer, buffer_size, + &length, "MINOR=%u", disk->first_minor); + } else if (ktype == &ktype_part) { + disk = container_of(kobj->parent, struct gendisk, kobj); + part = container_of(kobj, struct hd_struct, kobj); + add_hotplug_env_var(envp, num_envp, &i, buffer, buffer_size, + &length, "MINOR=%u", + disk->first_minor + part->partno); + } else + return 0; + + add_hotplug_env_var(envp, num_envp, &i, buffer, buffer_size, &length, + "MAJOR=%u", disk->major); + + /* add physical device, backing this device */ + physdev = disk->driverfs_dev; + if (physdev) { + char *path = kobject_get_path(&physdev->kobj, GFP_KERNEL); + + add_hotplug_env_var(envp, num_envp, &i, buffer, buffer_size, + &length, "PHYSDEVPATH=%s", path); + kfree(path); + + if (physdev->bus) + add_hotplug_env_var(envp, num_envp, &i, + buffer, buffer_size, &length, + "PHYSDEVBUS=%s", + physdev->bus->name); + + if (physdev->driver) + add_hotplug_env_var(envp, num_envp, &i, + buffer, buffer_size, &length, + "PHYSDEVDRIVER=%s", + physdev->driver->name); + } + + /* terminate, set to next free slot, shrink available space */ + envp[i] = NULL; + envp = &envp[i]; + num_envp -= i; + buffer = &buffer[length]; + buffer_size -= length; + + return 0; +} + +static struct kset_hotplug_ops block_hotplug_ops = { + .filter = block_hotplug_filter, + .hotplug = block_hotplug, +}; + +/* declare block_subsys. */ +static decl_subsys(block, &ktype_block, &block_hotplug_ops); + + +/* + * aggregate disk stat collector. Uses the same stats that the sysfs + * entries do, above, but makes them available through one seq_file. + * Watching a few disks may be efficient through sysfs, but watching + * all of them will be more efficient through this interface. + * + * The output looks suspiciously like /proc/partitions with a bunch of + * extra fields. + */ + +/* iterator */ +static void *diskstats_start(struct seq_file *part, loff_t *pos) +{ + loff_t k = *pos; + struct list_head *p; + + down(&block_subsys_sem); + list_for_each(p, &block_subsys.kset.list) + if (!k--) + return list_entry(p, struct gendisk, kobj.entry); + return NULL; +} + +static void *diskstats_next(struct seq_file *part, void *v, loff_t *pos) +{ + struct list_head *p = ((struct gendisk *)v)->kobj.entry.next; + ++*pos; + return p==&block_subsys.kset.list ? NULL : + list_entry(p, struct gendisk, kobj.entry); +} + +static void diskstats_stop(struct seq_file *part, void *v) +{ + up(&block_subsys_sem); +} + +static int diskstats_show(struct seq_file *s, void *v) +{ + struct gendisk *gp = v; + char buf[BDEVNAME_SIZE]; + int n = 0; + + /* + if (&sgp->kobj.entry == block_subsys.kset.list.next) + seq_puts(s, "major minor name" + " rio rmerge rsect ruse wio wmerge " + "wsect wuse running use aveq" + "\n\n"); + */ + + preempt_disable(); + disk_round_stats(gp); + preempt_enable(); + seq_printf(s, "%4d %4d %s %u %u %llu %u %u %u %llu %u %u %u %u\n", + gp->major, n + gp->first_minor, disk_name(gp, n, buf), + disk_stat_read(gp, ios[0]), disk_stat_read(gp, merges[0]), + (unsigned long long)disk_stat_read(gp, sectors[0]), + jiffies_to_msecs(disk_stat_read(gp, ticks[0])), + disk_stat_read(gp, ios[1]), disk_stat_read(gp, merges[1]), + (unsigned long long)disk_stat_read(gp, sectors[1]), + jiffies_to_msecs(disk_stat_read(gp, ticks[1])), + gp->in_flight, + jiffies_to_msecs(disk_stat_read(gp, io_ticks)), + jiffies_to_msecs(disk_stat_read(gp, time_in_queue))); + + /* now show all non-0 size partitions of it */ + for (n = 0; n < gp->minors - 1; n++) { + struct hd_struct *hd = gp->part[n]; + + if (hd && hd->nr_sects) + seq_printf(s, "%4d %4d %s %u %u %u %u\n", + gp->major, n + gp->first_minor + 1, + disk_name(gp, n + 1, buf), + hd->ios[0], hd->sectors[0], + hd->ios[1], hd->sectors[1]); + } + + return 0; +} + +struct seq_operations diskstats_op = { + .start = diskstats_start, + .next = diskstats_next, + .stop = diskstats_stop, + .show = diskstats_show +}; + +struct gendisk *alloc_disk(int minors) +{ + return alloc_disk_node(minors, -1); +} + +struct gendisk *alloc_disk_node(int minors, int node_id) +{ + struct gendisk *disk; + + disk = kmalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id); + if (disk) { + memset(disk, 0, sizeof(struct gendisk)); + if (!init_disk_stats(disk)) { + kfree(disk); + return NULL; + } + if (minors > 1) { + int size = (minors - 1) * sizeof(struct hd_struct *); + disk->part = kmalloc_node(size, GFP_KERNEL, node_id); + if (!disk->part) { + kfree(disk); + return NULL; + } + memset(disk->part, 0, size); + } + disk->minors = minors; + kobj_set_kset_s(disk,block_subsys); + kobject_init(&disk->kobj); + rand_initialize_disk(disk); + } + return disk; +} + +EXPORT_SYMBOL(alloc_disk); +EXPORT_SYMBOL(alloc_disk_node); + +struct kobject *get_disk(struct gendisk *disk) +{ + struct module *owner; + struct kobject *kobj; + + if (!disk->fops) + return NULL; + owner = disk->fops->owner; + if (owner && !try_module_get(owner)) + return NULL; + kobj = kobject_get(&disk->kobj); + if (kobj == NULL) { + module_put(owner); + return NULL; + } + return kobj; + +} + +EXPORT_SYMBOL(get_disk); + +void put_disk(struct gendisk *disk) +{ + if (disk) + kobject_put(&disk->kobj); +} + +EXPORT_SYMBOL(put_disk); + +void set_device_ro(struct block_device *bdev, int flag) +{ + if (bdev->bd_contains != bdev) + bdev->bd_part->policy = flag; + else + bdev->bd_disk->policy = flag; +} + +EXPORT_SYMBOL(set_device_ro); + +void set_disk_ro(struct gendisk *disk, int flag) +{ + int i; + disk->policy = flag; + for (i = 0; i < disk->minors - 1; i++) + if (disk->part[i]) disk->part[i]->policy = flag; +} + +EXPORT_SYMBOL(set_disk_ro); + +int bdev_read_only(struct block_device *bdev) +{ + if (!bdev) + return 0; + else if (bdev->bd_contains != bdev) + return bdev->bd_part->policy; + else + return bdev->bd_disk->policy; +} + +EXPORT_SYMBOL(bdev_read_only); + +int invalidate_partition(struct gendisk *disk, int index) +{ + int res = 0; + struct block_device *bdev = bdget_disk(disk, index); + if (bdev) { + fsync_bdev(bdev); + res = __invalidate_device(bdev); + bdput(bdev); + } + return res; +} + +EXPORT_SYMBOL(invalidate_partition); diff --git a/block/ioctl.c b/block/ioctl.c new file mode 100644 index 00000000000..6e278474f9a --- /dev/null +++ b/block/ioctl.c @@ -0,0 +1,275 @@ +#include <linux/sched.h> /* for capable() */ +#include <linux/blkdev.h> +#include <linux/blkpg.h> +#include <linux/backing-dev.h> +#include <linux/buffer_head.h> +#include <linux/smp_lock.h> +#include <asm/uaccess.h> + +static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user *arg) +{ + struct block_device *bdevp; + struct gendisk *disk; + struct blkpg_ioctl_arg a; + struct blkpg_partition p; + long long start, length; + int part; + int i; + + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + if (copy_from_user(&a, arg, sizeof(struct blkpg_ioctl_arg))) + return -EFAULT; + if (copy_from_user(&p, a.data, sizeof(struct blkpg_partition))) + return -EFAULT; + disk = bdev->bd_disk; + if (bdev != bdev->bd_contains) + return -EINVAL; + part = p.pno; + if (part <= 0 || part >= disk->minors) + return -EINVAL; + switch (a.op) { + case BLKPG_ADD_PARTITION: + start = p.start >> 9; + length = p.length >> 9; + /* check for fit in a hd_struct */ + if (sizeof(sector_t) == sizeof(long) && + sizeof(long long) > sizeof(long)) { + long pstart = start, plength = length; + if (pstart != start || plength != length + || pstart < 0 || plength < 0) + return -EINVAL; + } + /* partition number in use? */ + down(&bdev->bd_sem); + if (disk->part[part - 1]) { + up(&bdev->bd_sem); + return -EBUSY; + } + /* overlap? */ + for (i = 0; i < disk->minors - 1; i++) { + struct hd_struct *s = disk->part[i]; + + if (!s) + continue; + if (!(start+length <= s->start_sect || + start >= s->start_sect + s->nr_sects)) { + up(&bdev->bd_sem); + return -EBUSY; + } + } + /* all seems OK */ + add_partition(disk, part, start, length); + up(&bdev->bd_sem); + return 0; + case BLKPG_DEL_PARTITION: + if (!disk->part[part-1]) + return -ENXIO; + if (disk->part[part - 1]->nr_sects == 0) + return -ENXIO; + bdevp = bdget_disk(disk, part); + if (!bdevp) + return -ENOMEM; + down(&bdevp->bd_sem); + if (bdevp->bd_openers) { + up(&bdevp->bd_sem); + bdput(bdevp); + return -EBUSY; + } + /* all seems OK */ + fsync_bdev(bdevp); + invalidate_bdev(bdevp, 0); + + down(&bdev->bd_sem); + delete_partition(disk, part); + up(&bdev->bd_sem); + up(&bdevp->bd_sem); + bdput(bdevp); + + return 0; + default: + return -EINVAL; + } +} + +static int blkdev_reread_part(struct block_device *bdev) +{ + struct gendisk *disk = bdev->bd_disk; + int res; + + if (disk->minors == 1 || bdev != bdev->bd_contains) + return -EINVAL; + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + if (down_trylock(&bdev->bd_sem)) + return -EBUSY; + res = rescan_partitions(disk, bdev); + up(&bdev->bd_sem); + return res; +} + +static int put_ushort(unsigned long arg, unsigned short val) +{ + return put_user(val, (unsigned short __user *)arg); +} + +static int put_int(unsigned long arg, int val) +{ + return put_user(val, (int __user *)arg); +} + +static int put_long(unsigned long arg, long val) +{ + return put_user(val, (long __user *)arg); +} + +static int put_ulong(unsigned long arg, unsigned long val) +{ + return put_user(val, (unsigned long __user *)arg); +} + +static int put_u64(unsigned long arg, u64 val) +{ + return put_user(val, (u64 __user *)arg); +} + +static int blkdev_locked_ioctl(struct file *file, struct block_device *bdev, + unsigned cmd, unsigned long arg) +{ + struct backing_dev_info *bdi; + int ret, n; + + switch (cmd) { + case BLKRAGET: + case BLKFRAGET: + if (!arg) + return -EINVAL; + bdi = blk_get_backing_dev_info(bdev); + if (bdi == NULL) + return -ENOTTY; + return put_long(arg, (bdi->ra_pages * PAGE_CACHE_SIZE) / 512); + case BLKROGET: + return put_int(arg, bdev_read_only(bdev) != 0); + case BLKBSZGET: /* get the logical block size (cf. BLKSSZGET) */ + return put_int(arg, block_size(bdev)); + case BLKSSZGET: /* get block device hardware sector size */ + return put_int(arg, bdev_hardsect_size(bdev)); + case BLKSECTGET: + return put_ushort(arg, bdev_get_queue(bdev)->max_sectors); + case BLKRASET: + case BLKFRASET: + if(!capable(CAP_SYS_ADMIN)) + return -EACCES; + bdi = blk_get_backing_dev_info(bdev); + if (bdi == NULL) + return -ENOTTY; + bdi->ra_pages = (arg * 512) / PAGE_CACHE_SIZE; + return 0; + case BLKBSZSET: + /* set the logical block size */ + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + if (!arg) + return -EINVAL; + if (get_user(n, (int __user *) arg)) + return -EFAULT; + if (bd_claim(bdev, file) < 0) + return -EBUSY; + ret = set_blocksize(bdev, n); + bd_release(bdev); + return ret; + case BLKPG: + return blkpg_ioctl(bdev, (struct blkpg_ioctl_arg __user *) arg); + case BLKRRPART: + return blkdev_reread_part(bdev); + case BLKGETSIZE: + if ((bdev->bd_inode->i_size >> 9) > ~0UL) + return -EFBIG; + return put_ulong(arg, bdev->bd_inode->i_size >> 9); + case BLKGETSIZE64: + return put_u64(arg, bdev->bd_inode->i_size); + } + return -ENOIOCTLCMD; +} + +static int blkdev_driver_ioctl(struct inode *inode, struct file *file, + struct gendisk *disk, unsigned cmd, unsigned long arg) +{ + int ret; + if (disk->fops->unlocked_ioctl) + return disk->fops->unlocked_ioctl(file, cmd, arg); + + if (disk->fops->ioctl) { + lock_kernel(); + ret = disk->fops->ioctl(inode, file, cmd, arg); + unlock_kernel(); + return ret; + } + + return -ENOTTY; +} + +int blkdev_ioctl(struct inode *inode, struct file *file, unsigned cmd, + unsigned long arg) +{ + struct block_device *bdev = inode->i_bdev; + struct gendisk *disk = bdev->bd_disk; + int ret, n; + + switch(cmd) { + case BLKFLSBUF: + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + + ret = blkdev_driver_ioctl(inode, file, disk, cmd, arg); + /* -EINVAL to handle old uncorrected drivers */ + if (ret != -EINVAL && ret != -ENOTTY) + return ret; + + lock_kernel(); + fsync_bdev(bdev); + invalidate_bdev(bdev, 0); + unlock_kernel(); + return 0; + + case BLKROSET: + ret = blkdev_driver_ioctl(inode, file, disk, cmd, arg); + /* -EINVAL to handle old uncorrected drivers */ + if (ret != -EINVAL && ret != -ENOTTY) + return ret; + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + if (get_user(n, (int __user *)(arg))) + return -EFAULT; + lock_kernel(); + set_device_ro(bdev, n); + unlock_kernel(); + return 0; + } + + lock_kernel(); + ret = blkdev_locked_ioctl(file, bdev, cmd, arg); + unlock_kernel(); + if (ret != -ENOIOCTLCMD) + return ret; + + return blkdev_driver_ioctl(inode, file, disk, cmd, arg); +} + +/* Most of the generic ioctls are handled in the normal fallback path. + This assumes the blkdev's low level compat_ioctl always returns + ENOIOCTLCMD for unknown ioctls. */ +long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg) +{ + struct block_device *bdev = file->f_dentry->d_inode->i_bdev; + struct gendisk *disk = bdev->bd_disk; + int ret = -ENOIOCTLCMD; + if (disk->fops->compat_ioctl) { + lock_kernel(); + ret = disk->fops->compat_ioctl(file, cmd, arg); + unlock_kernel(); + } + return ret; +} + +EXPORT_SYMBOL_GPL(blkdev_ioctl); diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c new file mode 100644 index 00000000000..5f52e30b43f --- /dev/null +++ b/block/ll_rw_blk.c @@ -0,0 +1,3612 @@ +/* + * linux/drivers/block/ll_rw_blk.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + * Copyright (C) 1994, Karl Keyte: Added support for disk statistics + * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE + * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de> + * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> - July2000 + * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001 + */ + +/* + * This handles all read/write requests to block devices + */ +#include <linux/config.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/backing-dev.h> +#include <linux/bio.h> +#include <linux/blkdev.h> +#include <linux/highmem.h> +#include <linux/mm.h> +#include <linux/kernel_stat.h> +#include <linux/string.h> +#include <linux/init.h> +#include <linux/bootmem.h> /* for max_pfn/max_low_pfn */ +#include <linux/completion.h> +#include <linux/slab.h> +#include <linux/swap.h> +#include <linux/writeback.h> +#include <linux/blkdev.h> + +/* + * for max sense size + */ +#include <scsi/scsi_cmnd.h> + +static void blk_unplug_work(void *data); +static void blk_unplug_timeout(unsigned long data); +static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io); + +/* + * For the allocated request tables + */ +static kmem_cache_t *request_cachep; + +/* + * For queue allocation + */ +static kmem_cache_t *requestq_cachep; + +/* + * For io context allocations + */ +static kmem_cache_t *iocontext_cachep; + +static wait_queue_head_t congestion_wqh[2] = { + __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), + __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) + }; + +/* + * Controlling structure to kblockd + */ +static struct workqueue_struct *kblockd_workqueue; + +unsigned long blk_max_low_pfn, blk_max_pfn; + +EXPORT_SYMBOL(blk_max_low_pfn); +EXPORT_SYMBOL(blk_max_pfn); + +/* Amount of time in which a process may batch requests */ +#define BLK_BATCH_TIME (HZ/50UL) + +/* Number of requests a "batching" process may submit */ +#define BLK_BATCH_REQ 32 + +/* + * Return the threshold (number of used requests) at which the queue is + * considered to be congested. It include a little hysteresis to keep the + * context switch rate down. + */ +static inline int queue_congestion_on_threshold(struct request_queue *q) +{ + return q->nr_congestion_on; +} + +/* + * The threshold at which a queue is considered to be uncongested + */ +static inline int queue_congestion_off_threshold(struct request_queue *q) +{ + return q->nr_congestion_off; +} + +static void blk_queue_congestion_threshold(struct request_queue *q) +{ + int nr; + + nr = q->nr_requests - (q->nr_requests / 8) + 1; + if (nr > q->nr_requests) + nr = q->nr_requests; + q->nr_congestion_on = nr; + + nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1; + if (nr < 1) + nr = 1; + q->nr_congestion_off = nr; +} + +/* + * A queue has just exitted congestion. Note this in the global counter of + * congested queues, and wake up anyone who was waiting for requests to be + * put back. + */ +static void clear_queue_congested(request_queue_t *q, int rw) +{ + enum bdi_state bit; + wait_queue_head_t *wqh = &congestion_wqh[rw]; + + bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; + clear_bit(bit, &q->backing_dev_info.state); + smp_mb__after_clear_bit(); + if (waitqueue_active(wqh)) + wake_up(wqh); +} + +/* + * A queue has just entered congestion. Flag that in the queue's VM-visible + * state flags and increment the global gounter of congested queues. + */ +static void set_queue_congested(request_queue_t *q, int rw) +{ + enum bdi_state bit; + + bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; + set_bit(bit, &q->backing_dev_info.state); +} + +/** + * blk_get_backing_dev_info - get the address of a queue's backing_dev_info + * @bdev: device + * + * Locates the passed device's request queue and returns the address of its + * backing_dev_info + * + * Will return NULL if the request queue cannot be located. + */ +struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) +{ + struct backing_dev_info *ret = NULL; + request_queue_t *q = bdev_get_queue(bdev); + + if (q) + ret = &q->backing_dev_info; + return ret; +} + +EXPORT_SYMBOL(blk_get_backing_dev_info); + +void blk_queue_activity_fn(request_queue_t *q, activity_fn *fn, void *data) +{ + q->activity_fn = fn; + q->activity_data = data; +} + +EXPORT_SYMBOL(blk_queue_activity_fn); + +/** + * blk_queue_prep_rq - set a prepare_request function for queue + * @q: queue + * @pfn: prepare_request function + * + * It's possible for a queue to register a prepare_request callback which + * is invoked before the request is handed to the request_fn. The goal of + * the function is to prepare a request for I/O, it can be used to build a + * cdb from the request data for instance. + * + */ +void blk_queue_prep_rq(request_queue_t *q, prep_rq_fn *pfn) +{ + q->prep_rq_fn = pfn; +} + +EXPORT_SYMBOL(blk_queue_prep_rq); + +/** + * blk_queue_merge_bvec - set a merge_bvec function for queue + * @q: queue + * @mbfn: merge_bvec_fn + * + * Usually queues have static limitations on the max sectors or segments that + * we can put in a request. Stacking drivers may have some settings that + * are dynamic, and thus we have to query the queue whether it is ok to + * add a new bio_vec to a bio at a given offset or not. If the block device + * has such limitations, it needs to register a merge_bvec_fn to control + * the size of bio's sent to it. Note that a block device *must* allow a + * single page to be added to an empty bio. The block device driver may want + * to use the bio_split() function to deal with these bio's. By default + * no merge_bvec_fn is defined for a queue, and only the fixed limits are + * honored. + */ +void blk_queue_merge_bvec(request_queue_t *q, merge_bvec_fn *mbfn) +{ + q->merge_bvec_fn = mbfn; +} + +EXPORT_SYMBOL(blk_queue_merge_bvec); + +/** + * blk_queue_make_request - define an alternate make_request function for a device + * @q: the request queue for the device to be affected + * @mfn: the alternate make_request function + * + * Description: + * The normal way for &struct bios to be passed to a device + * driver is for them to be collected into requests on a request + * queue, and then to allow the device driver to select requests + * off that queue when it is ready. This works well for many block + * devices. However some block devices (typically virtual devices + * such as md or lvm) do not benefit from the processing on the + * request queue, and are served best by having the requests passed + * directly to them. This can be achieved by providing a function + * to blk_queue_make_request(). + * + * Caveat: + * The driver that does this *must* be able to deal appropriately + * with buffers in "highmemory". This can be accomplished by either calling + * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling + * blk_queue_bounce() to create a buffer in normal memory. + **/ +void blk_queue_make_request(request_queue_t * q, make_request_fn * mfn) +{ + /* + * set defaults + */ + q->nr_requests = BLKDEV_MAX_RQ; + blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS); + blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS); + q->make_request_fn = mfn; + q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; + q->backing_dev_info.state = 0; + q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; + blk_queue_max_sectors(q, MAX_SECTORS); + blk_queue_hardsect_size(q, 512); + blk_queue_dma_alignment(q, 511); + blk_queue_congestion_threshold(q); + q->nr_batching = BLK_BATCH_REQ; + + q->unplug_thresh = 4; /* hmm */ + q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */ + if (q->unplug_delay == 0) + q->unplug_delay = 1; + + INIT_WORK(&q->unplug_work, blk_unplug_work, q); + + q->unplug_timer.function = blk_unplug_timeout; + q->unplug_timer.data = (unsigned long)q; + + /* + * by default assume old behaviour and bounce for any highmem page + */ + blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH); + + blk_queue_activity_fn(q, NULL, NULL); +} + +EXPORT_SYMBOL(blk_queue_make_request); + +static inline void rq_init(request_queue_t *q, struct request *rq) +{ + INIT_LIST_HEAD(&rq->queuelist); + + rq->errors = 0; + rq->rq_status = RQ_ACTIVE; + rq->bio = rq->biotail = NULL; + rq->ioprio = 0; + rq->buffer = NULL; + rq->ref_count = 1; + rq->q = q; + rq->waiting = NULL; + rq->special = NULL; + rq->data_len = 0; + rq->data = NULL; + rq->nr_phys_segments = 0; + rq->sense = NULL; + rq->end_io = NULL; + rq->end_io_data = NULL; +} + +/** + * blk_queue_ordered - does this queue support ordered writes + * @q: the request queue + * @flag: see below + * + * Description: + * For journalled file systems, doing ordered writes on a commit + * block instead of explicitly doing wait_on_buffer (which is bad + * for performance) can be a big win. Block drivers supporting this + * feature should call this function and indicate so. + * + **/ +void blk_queue_ordered(request_queue_t *q, int flag) +{ + switch (flag) { + case QUEUE_ORDERED_NONE: + if (q->flush_rq) + kmem_cache_free(request_cachep, q->flush_rq); + q->flush_rq = NULL; + q->ordered = flag; + break; + case QUEUE_ORDERED_TAG: + q->ordered = flag; + break; + case QUEUE_ORDERED_FLUSH: + q->ordered = flag; + if (!q->flush_rq) + q->flush_rq = kmem_cache_alloc(request_cachep, + GFP_KERNEL); + break; + default: + printk("blk_queue_ordered: bad value %d\n", flag); + break; + } +} + +EXPORT_SYMBOL(blk_queue_ordered); + +/** + * blk_queue_issue_flush_fn - set function for issuing a flush + * @q: the request queue + * @iff: the function to be called issuing the flush + * + * Description: + * If a driver supports issuing a flush command, the support is notified + * to the block layer by defining it through this call. + * + **/ +void blk_queue_issue_flush_fn(request_queue_t *q, issue_flush_fn *iff) +{ + q->issue_flush_fn = iff; +} + +EXPORT_SYMBOL(blk_queue_issue_flush_fn); + +/* + * Cache flushing for ordered writes handling + */ +static void blk_pre_flush_end_io(struct request *flush_rq) +{ + struct request *rq = flush_rq->end_io_data; + request_queue_t *q = rq->q; + + elv_completed_request(q, flush_rq); + + rq->flags |= REQ_BAR_PREFLUSH; + + if (!flush_rq->errors) + elv_requeue_request(q, rq); + else { + q->end_flush_fn(q, flush_rq); + clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags); + q->request_fn(q); + } +} + +static void blk_post_flush_end_io(struct request *flush_rq) +{ + struct request *rq = flush_rq->end_io_data; + request_queue_t *q = rq->q; + + elv_completed_request(q, flush_rq); + + rq->flags |= REQ_BAR_POSTFLUSH; + + q->end_flush_fn(q, flush_rq); + clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags); + q->request_fn(q); +} + +struct request *blk_start_pre_flush(request_queue_t *q, struct request *rq) +{ + struct request *flush_rq = q->flush_rq; + + BUG_ON(!blk_barrier_rq(rq)); + + if (test_and_set_bit(QUEUE_FLAG_FLUSH, &q->queue_flags)) + return NULL; + + rq_init(q, flush_rq); + flush_rq->elevator_private = NULL; + flush_rq->flags = REQ_BAR_FLUSH; + flush_rq->rq_disk = rq->rq_disk; + flush_rq->rl = NULL; + + /* + * prepare_flush returns 0 if no flush is needed, just mark both + * pre and post flush as done in that case + */ + if (!q->prepare_flush_fn(q, flush_rq)) { + rq->flags |= REQ_BAR_PREFLUSH | REQ_BAR_POSTFLUSH; + clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags); + return rq; + } + + /* + * some drivers dequeue requests right away, some only after io + * completion. make sure the request is dequeued. + */ + if (!list_empty(&rq->queuelist)) + blkdev_dequeue_request(rq); + + flush_rq->end_io_data = rq; + flush_rq->end_io = blk_pre_flush_end_io; + + __elv_add_request(q, flush_rq, ELEVATOR_INSERT_FRONT, 0); + return flush_rq; +} + +static void blk_start_post_flush(request_queue_t *q, struct request *rq) +{ + struct request *flush_rq = q->flush_rq; + + BUG_ON(!blk_barrier_rq(rq)); + + rq_init(q, flush_rq); + flush_rq->elevator_private = NULL; + flush_rq->flags = REQ_BAR_FLUSH; + flush_rq->rq_disk = rq->rq_disk; + flush_rq->rl = NULL; + + if (q->prepare_flush_fn(q, flush_rq)) { + flush_rq->end_io_data = rq; + flush_rq->end_io = blk_post_flush_end_io; + + __elv_add_request(q, flush_rq, ELEVATOR_INSERT_FRONT, 0); + q->request_fn(q); + } +} + +static inline int blk_check_end_barrier(request_queue_t *q, struct request *rq, + int sectors) +{ + if (sectors > rq->nr_sectors) + sectors = rq->nr_sectors; + + rq->nr_sectors -= sectors; + return rq->nr_sectors; +} + +static int __blk_complete_barrier_rq(request_queue_t *q, struct request *rq, + int sectors, int queue_locked) +{ + if (q->ordered != QUEUE_ORDERED_FLUSH) + return 0; + if (!blk_fs_request(rq) || !blk_barrier_rq(rq)) + return 0; + if (blk_barrier_postflush(rq)) + return 0; + + if (!blk_check_end_barrier(q, rq, sectors)) { + unsigned long flags = 0; + + if (!queue_locked) + spin_lock_irqsave(q->queue_lock, flags); + + blk_start_post_flush(q, rq); + + if (!queue_locked) + spin_unlock_irqrestore(q->queue_lock, flags); + } + + return 1; +} + +/** + * blk_complete_barrier_rq - complete possible barrier request + * @q: the request queue for the device + * @rq: the request + * @sectors: number of sectors to complete + * + * Description: + * Used in driver end_io handling to determine whether to postpone + * completion of a barrier request until a post flush has been done. This + * is the unlocked variant, used if the caller doesn't already hold the + * queue lock. + **/ +int blk_complete_barrier_rq(request_queue_t *q, struct request *rq, int sectors) +{ + return __blk_complete_barrier_rq(q, rq, sectors, 0); +} +EXPORT_SYMBOL(blk_complete_barrier_rq); + +/** + * blk_complete_barrier_rq_locked - complete possible barrier request + * @q: the request queue for the device + * @rq: the request + * @sectors: number of sectors to complete + * + * Description: + * See blk_complete_barrier_rq(). This variant must be used if the caller + * holds the queue lock. + **/ +int blk_complete_barrier_rq_locked(request_queue_t *q, struct request *rq, + int sectors) +{ + return __blk_complete_barrier_rq(q, rq, sectors, 1); +} +EXPORT_SYMBOL(blk_complete_barrier_rq_locked); + +/** + * blk_queue_bounce_limit - set bounce buffer limit for queue + * @q: the request queue for the device + * @dma_addr: bus address limit + * + * Description: + * Different hardware can have different requirements as to what pages + * it can do I/O directly to. A low level driver can call + * blk_queue_bounce_limit to have lower memory pages allocated as bounce + * buffers for doing I/O to pages residing above @page. By default + * the block layer sets this to the highest numbered "low" memory page. + **/ +void blk_queue_bounce_limit(request_queue_t *q, u64 dma_addr) +{ + unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT; + + /* + * set appropriate bounce gfp mask -- unfortunately we don't have a + * full 4GB zone, so we have to resort to low memory for any bounces. + * ISA has its own < 16MB zone. + */ + if (bounce_pfn < blk_max_low_pfn) { + BUG_ON(dma_addr < BLK_BOUNCE_ISA); + init_emergency_isa_pool(); + q->bounce_gfp = GFP_NOIO | GFP_DMA; + } else + q->bounce_gfp = GFP_NOIO; + + q->bounce_pfn = bounce_pfn; +} + +EXPORT_SYMBOL(blk_queue_bounce_limit); + +/** + * blk_queue_max_sectors - set max sectors for a request for this queue + * @q: the request queue for the device + * @max_sectors: max sectors in the usual 512b unit + * + * Description: + * Enables a low level driver to set an upper limit on the size of + * received requests. + **/ +void blk_queue_max_sectors(request_queue_t *q, unsigned short max_sectors) +{ + if ((max_sectors << 9) < PAGE_CACHE_SIZE) { + max_sectors = 1 << (PAGE_CACHE_SHIFT - 9); + printk("%s: set to minimum %d\n", __FUNCTION__, max_sectors); + } + + q->max_sectors = q->max_hw_sectors = max_sectors; +} + +EXPORT_SYMBOL(blk_queue_max_sectors); + +/** + * blk_queue_max_phys_segments - set max phys segments for a request for this queue + * @q: the request queue for the device + * @max_segments: max number of segments + * + * Description: + * Enables a low level driver to set an upper limit on the number of + * physical data segments in a request. This would be the largest sized + * scatter list the driver could handle. + **/ +void blk_queue_max_phys_segments(request_queue_t *q, unsigned short max_segments) +{ + if (!max_segments) { + max_segments = 1; + printk("%s: set to minimum %d\n", __FUNCTION__, max_segments); + } + + q->max_phys_segments = max_segments; +} + +EXPORT_SYMBOL(blk_queue_max_phys_segments); + +/** + * blk_queue_max_hw_segments - set max hw segments for a request for this queue + * @q: the request queue for the device + * @max_segments: max number of segments + * + * Description: + * Enables a low level driver to set an upper limit on the number of + * hw data segments in a request. This would be the largest number of + * address/length pairs the host adapter can actually give as once + * to the device. + **/ +void blk_queue_max_hw_segments(request_queue_t *q, unsigned short max_segments) +{ + if (!max_segments) { + max_segments = 1; + printk("%s: set to minimum %d\n", __FUNCTION__, max_segments); + } + + q->max_hw_segments = max_segments; +} + +EXPORT_SYMBOL(blk_queue_max_hw_segments); + +/** + * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg + * @q: the request queue for the device + * @max_size: max size of segment in bytes + * + * Description: + * Enables a low level driver to set an upper limit on the size of a + * coalesced segment + **/ +void blk_queue_max_segment_size(request_queue_t *q, unsigned int max_size) +{ + if (max_size < PAGE_CACHE_SIZE) { + max_size = PAGE_CACHE_SIZE; + printk("%s: set to minimum %d\n", __FUNCTION__, max_size); + } + + q->max_segment_size = max_size; +} + +EXPORT_SYMBOL(blk_queue_max_segment_size); + +/** + * blk_queue_hardsect_size - set hardware sector size for the queue + * @q: the request queue for the device + * @size: the hardware sector size, in bytes + * + * Description: + * This should typically be set to the lowest possible sector size + * that the hardware can operate on (possible without reverting to + * even internal read-modify-write operations). Usually the default + * of 512 covers most hardware. + **/ +void blk_queue_hardsect_size(request_queue_t *q, unsigned short size) +{ + q->hardsect_size = size; +} + +EXPORT_SYMBOL(blk_queue_hardsect_size); + +/* + * Returns the minimum that is _not_ zero, unless both are zero. + */ +#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) + +/** + * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers + * @t: the stacking driver (top) + * @b: the underlying device (bottom) + **/ +void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b) +{ + /* zero is "infinity" */ + t->max_sectors = t->max_hw_sectors = + min_not_zero(t->max_sectors,b->max_sectors); + + t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments); + t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments); + t->max_segment_size = min(t->max_segment_size,b->max_segment_size); + t->hardsect_size = max(t->hardsect_size,b->hardsect_size); +} + +EXPORT_SYMBOL(blk_queue_stack_limits); + +/** + * blk_queue_segment_boundary - set boundary rules for segment merging + * @q: the request queue for the device + * @mask: the memory boundary mask + **/ +void blk_queue_segment_boundary(request_queue_t *q, unsigned long mask) +{ + if (mask < PAGE_CACHE_SIZE - 1) { + mask = PAGE_CACHE_SIZE - 1; + printk("%s: set to minimum %lx\n", __FUNCTION__, mask); + } + + q->seg_boundary_mask = mask; +} + +EXPORT_SYMBOL(blk_queue_segment_boundary); + +/** + * blk_queue_dma_alignment - set dma length and memory alignment + * @q: the request queue for the device + * @mask: alignment mask + * + * description: + * set required memory and length aligment for direct dma transactions. + * this is used when buiding direct io requests for the queue. + * + **/ +void blk_queue_dma_alignment(request_queue_t *q, int mask) +{ + q->dma_alignment = mask; +} + +EXPORT_SYMBOL(blk_queue_dma_alignment); + +/** + * blk_queue_find_tag - find a request by its tag and queue + * @q: The request queue for the device + * @tag: The tag of the request + * + * Notes: + * Should be used when a device returns a tag and you want to match + * it with a request. + * + * no locks need be held. + **/ +struct request *blk_queue_find_tag(request_queue_t *q, int tag) +{ + struct blk_queue_tag *bqt = q->queue_tags; + + if (unlikely(bqt == NULL || tag >= bqt->real_max_depth)) + return NULL; + + return bqt->tag_index[tag]; +} + +EXPORT_SYMBOL(blk_queue_find_tag); + +/** + * __blk_queue_free_tags - release tag maintenance info + * @q: the request queue for the device + * + * Notes: + * blk_cleanup_queue() will take care of calling this function, if tagging + * has been used. So there's no need to call this directly. + **/ +static void __blk_queue_free_tags(request_queue_t *q) +{ + struct blk_queue_tag *bqt = q->queue_tags; + + if (!bqt) + return; + + if (atomic_dec_and_test(&bqt->refcnt)) { + BUG_ON(bqt->busy); + BUG_ON(!list_empty(&bqt->busy_list)); + + kfree(bqt->tag_index); + bqt->tag_index = NULL; + + kfree(bqt->tag_map); + bqt->tag_map = NULL; + + kfree(bqt); + } + + q->queue_tags = NULL; + q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED); +} + +/** + * blk_queue_free_tags - release tag maintenance info + * @q: the request queue for the device + * + * Notes: + * This is used to disabled tagged queuing to a device, yet leave + * queue in function. + **/ +void blk_queue_free_tags(request_queue_t *q) +{ + clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); +} + +EXPORT_SYMBOL(blk_queue_free_tags); + +static int +init_tag_map(request_queue_t *q, struct blk_queue_tag *tags, int depth) +{ + struct request **tag_index; + unsigned long *tag_map; + int nr_ulongs; + + if (depth > q->nr_requests * 2) { + depth = q->nr_requests * 2; + printk(KERN_ERR "%s: adjusted depth to %d\n", + __FUNCTION__, depth); + } + + tag_index = kmalloc(depth * sizeof(struct request *), GFP_ATOMIC); + if (!tag_index) + goto fail; + + nr_ulongs = ALIGN(depth, BITS_PER_LONG) / BITS_PER_LONG; + tag_map = kmalloc(nr_ulongs * sizeof(unsigned long), GFP_ATOMIC); + if (!tag_map) + goto fail; + + memset(tag_index, 0, depth * sizeof(struct request *)); + memset(tag_map, 0, nr_ulongs * sizeof(unsigned long)); + tags->real_max_depth = depth; + tags->max_depth = depth; + tags->tag_index = tag_index; + tags->tag_map = tag_map; + + return 0; +fail: + kfree(tag_index); + return -ENOMEM; +} + +/** + * blk_queue_init_tags - initialize the queue tag info + * @q: the request queue for the device + * @depth: the maximum queue depth supported + * @tags: the tag to use + **/ +int blk_queue_init_tags(request_queue_t *q, int depth, + struct blk_queue_tag *tags) +{ + int rc; + + BUG_ON(tags && q->queue_tags && tags != q->queue_tags); + + if (!tags && !q->queue_tags) { + tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC); + if (!tags) + goto fail; + + if (init_tag_map(q, tags, depth)) + goto fail; + + INIT_LIST_HEAD(&tags->busy_list); + tags->busy = 0; + atomic_set(&tags->refcnt, 1); + } else if (q->queue_tags) { + if ((rc = blk_queue_resize_tags(q, depth))) + return rc; + set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); + return 0; + } else + atomic_inc(&tags->refcnt); + + /* + * assign it, all done + */ + q->queue_tags = tags; + q->queue_flags |= (1 << QUEUE_FLAG_QUEUED); + return 0; +fail: + kfree(tags); + return -ENOMEM; +} + +EXPORT_SYMBOL(blk_queue_init_tags); + +/** + * blk_queue_resize_tags - change the queueing depth + * @q: the request queue for the device + * @new_depth: the new max command queueing depth + * + * Notes: + * Must be called with the queue lock held. + **/ +int blk_queue_resize_tags(request_queue_t *q, int new_depth) +{ + struct blk_queue_tag *bqt = q->queue_tags; + struct request **tag_index; + unsigned long *tag_map; + int max_depth, nr_ulongs; + + if (!bqt) + return -ENXIO; + + /* + * if we already have large enough real_max_depth. just + * adjust max_depth. *NOTE* as requests with tag value + * between new_depth and real_max_depth can be in-flight, tag + * map can not be shrunk blindly here. + */ + if (new_depth <= bqt->real_max_depth) { + bqt->max_depth = new_depth; + return 0; + } + + /* + * save the old state info, so we can copy it back + */ + tag_index = bqt->tag_index; + tag_map = bqt->tag_map; + max_depth = bqt->real_max_depth; + + if (init_tag_map(q, bqt, new_depth)) + return -ENOMEM; + + memcpy(bqt->tag_index, tag_index, max_depth * sizeof(struct request *)); + nr_ulongs = ALIGN(max_depth, BITS_PER_LONG) / BITS_PER_LONG; + memcpy(bqt->tag_map, tag_map, nr_ulongs * sizeof(unsigned long)); + + kfree(tag_index); + kfree(tag_map); + return 0; +} + +EXPORT_SYMBOL(blk_queue_resize_tags); + +/** + * blk_queue_end_tag - end tag operations for a request + * @q: the request queue for the device + * @rq: the request that has completed + * + * Description: + * Typically called when end_that_request_first() returns 0, meaning + * all transfers have been done for a request. It's important to call + * this function before end_that_request_last(), as that will put the + * request back on the free list thus corrupting the internal tag list. + * + * Notes: + * queue lock must be held. + **/ +void blk_queue_end_tag(request_queue_t *q, struct request *rq) +{ + struct blk_queue_tag *bqt = q->queue_tags; + int tag = rq->tag; + + BUG_ON(tag == -1); + + if (unlikely(tag >= bqt->real_max_depth)) + /* + * This can happen after tag depth has been reduced. + * FIXME: how about a warning or info message here? + */ + return; + + if (unlikely(!__test_and_clear_bit(tag, bqt->tag_map))) { + printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n", + __FUNCTION__, tag); + return; + } + + list_del_init(&rq->queuelist); + rq->flags &= ~REQ_QUEUED; + rq->tag = -1; + + if (unlikely(bqt->tag_index[tag] == NULL)) + printk(KERN_ERR "%s: tag %d is missing\n", + __FUNCTION__, tag); + + bqt->tag_index[tag] = NULL; + bqt->busy--; +} + +EXPORT_SYMBOL(blk_queue_end_tag); + +/** + * blk_queue_start_tag - find a free tag and assign it + * @q: the request queue for the device + * @rq: the block request that needs tagging + * + * Description: + * This can either be used as a stand-alone helper, or possibly be + * assigned as the queue &prep_rq_fn (in which case &struct request + * automagically gets a tag assigned). Note that this function + * assumes that any type of request can be queued! if this is not + * true for your device, you must check the request type before + * calling this function. The request will also be removed from + * the request queue, so it's the drivers responsibility to readd + * it if it should need to be restarted for some reason. + * + * Notes: + * queue lock must be held. + **/ +int blk_queue_start_tag(request_queue_t *q, struct request *rq) +{ + struct blk_queue_tag *bqt = q->queue_tags; + int tag; + + if (unlikely((rq->flags & REQ_QUEUED))) { + printk(KERN_ERR + "%s: request %p for device [%s] already tagged %d", + __FUNCTION__, rq, + rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->tag); + BUG(); + } + + tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth); + if (tag >= bqt->max_depth) + return 1; + + __set_bit(tag, bqt->tag_map); + + rq->flags |= REQ_QUEUED; + rq->tag = tag; + bqt->tag_index[tag] = rq; + blkdev_dequeue_request(rq); + list_add(&rq->queuelist, &bqt->busy_list); + bqt->busy++; + return 0; +} + +EXPORT_SYMBOL(blk_queue_start_tag); + +/** + * blk_queue_invalidate_tags - invalidate all pending tags + * @q: the request queue for the device + * + * Description: + * Hardware conditions may dictate a need to stop all pending requests. + * In this case, we will safely clear the block side of the tag queue and + * readd all requests to the request queue in the right order. + * + * Notes: + * queue lock must be held. + **/ +void blk_queue_invalidate_tags(request_queue_t *q) +{ + struct blk_queue_tag *bqt = q->queue_tags; + struct list_head *tmp, *n; + struct request *rq; + + list_for_each_safe(tmp, n, &bqt->busy_list) { + rq = list_entry_rq(tmp); + + if (rq->tag == -1) { + printk(KERN_ERR + "%s: bad tag found on list\n", __FUNCTION__); + list_del_init(&rq->queuelist); + rq->flags &= ~REQ_QUEUED; + } else + blk_queue_end_tag(q, rq); + + rq->flags &= ~REQ_STARTED; + __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); + } +} + +EXPORT_SYMBOL(blk_queue_invalidate_tags); + +static char *rq_flags[] = { + "REQ_RW", + "REQ_FAILFAST", + "REQ_SORTED", + "REQ_SOFTBARRIER", + "REQ_HARDBARRIER", + "REQ_CMD", + "REQ_NOMERGE", + "REQ_STARTED", + "REQ_DONTPREP", + "REQ_QUEUED", + "REQ_ELVPRIV", + "REQ_PC", + "REQ_BLOCK_PC", + "REQ_SENSE", + "REQ_FAILED", + "REQ_QUIET", + "REQ_SPECIAL", + "REQ_DRIVE_CMD", + "REQ_DRIVE_TASK", + "REQ_DRIVE_TASKFILE", + "REQ_PREEMPT", + "REQ_PM_SUSPEND", + "REQ_PM_RESUME", + "REQ_PM_SHUTDOWN", +}; + +void blk_dump_rq_flags(struct request *rq, char *msg) +{ + int bit; + + printk("%s: dev %s: flags = ", msg, + rq->rq_disk ? rq->rq_disk->disk_name : "?"); + bit = 0; + do { + if (rq->flags & (1 << bit)) + printk("%s ", rq_flags[bit]); + bit++; + } while (bit < __REQ_NR_BITS); + + printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq->sector, + rq->nr_sectors, + rq->current_nr_sectors); + printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq->bio, rq->biotail, rq->buffer, rq->data, rq->data_len); + + if (rq->flags & (REQ_BLOCK_PC | REQ_PC)) { + printk("cdb: "); + for (bit = 0; bit < sizeof(rq->cmd); bit++) + printk("%02x ", rq->cmd[bit]); + printk("\n"); + } +} + +EXPORT_SYMBOL(blk_dump_rq_flags); + +void blk_recount_segments(request_queue_t *q, struct bio *bio) +{ + struct bio_vec *bv, *bvprv = NULL; + int i, nr_phys_segs, nr_hw_segs, seg_size, hw_seg_size, cluster; + int high, highprv = 1; + + if (unlikely(!bio->bi_io_vec)) + return; + + cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); + hw_seg_size = seg_size = nr_phys_segs = nr_hw_segs = 0; + bio_for_each_segment(bv, bio, i) { + /* + * the trick here is making sure that a high page is never + * considered part of another segment, since that might + * change with the bounce page. + */ + high = page_to_pfn(bv->bv_page) >= q->bounce_pfn; + if (high || highprv) + goto new_hw_segment; + if (cluster) { + if (seg_size + bv->bv_len > q->max_segment_size) + goto new_segment; + if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv)) + goto new_segment; + if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv)) + goto new_segment; + if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) + goto new_hw_segment; + + seg_size += bv->bv_len; + hw_seg_size += bv->bv_len; + bvprv = bv; + continue; + } +new_segment: + if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) && + !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) { + hw_seg_size += bv->bv_len; + } else { +new_hw_segment: + if (hw_seg_size > bio->bi_hw_front_size) + bio->bi_hw_front_size = hw_seg_size; + hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len; + nr_hw_segs++; + } + + nr_phys_segs++; + bvprv = bv; + seg_size = bv->bv_len; + highprv = high; + } + if (hw_seg_size > bio->bi_hw_back_size) + bio->bi_hw_back_size = hw_seg_size; + if (nr_hw_segs == 1 && hw_seg_size > bio->bi_hw_front_size) + bio->bi_hw_front_size = hw_seg_size; + bio->bi_phys_segments = nr_phys_segs; + bio->bi_hw_segments = nr_hw_segs; + bio->bi_flags |= (1 << BIO_SEG_VALID); +} + + +static int blk_phys_contig_segment(request_queue_t *q, struct bio *bio, + struct bio *nxt) +{ + if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER))) + return 0; + + if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt))) + return 0; + if (bio->bi_size + nxt->bi_size > q->max_segment_size) + return 0; + + /* + * bio and nxt are contigous in memory, check if the queue allows + * these two to be merged into one + */ + if (BIO_SEG_BOUNDARY(q, bio, nxt)) + return 1; + + return 0; +} + +static int blk_hw_contig_segment(request_queue_t *q, struct bio *bio, + struct bio *nxt) +{ + if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) + blk_recount_segments(q, bio); + if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID))) + blk_recount_segments(q, nxt); + if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) || + BIOVEC_VIRT_OVERSIZE(bio->bi_hw_front_size + bio->bi_hw_back_size)) + return 0; + if (bio->bi_size + nxt->bi_size > q->max_segment_size) + return 0; + + return 1; +} + +/* + * map a request to scatterlist, return number of sg entries setup. Caller + * must make sure sg can hold rq->nr_phys_segments entries + */ +int blk_rq_map_sg(request_queue_t *q, struct request *rq, struct scatterlist *sg) +{ + struct bio_vec *bvec, *bvprv; + struct bio *bio; + int nsegs, i, cluster; + + nsegs = 0; + cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); + + /* + * for each bio in rq + */ + bvprv = NULL; + rq_for_each_bio(bio, rq) { + /* + * for each segment in bio + */ + bio_for_each_segment(bvec, bio, i) { + int nbytes = bvec->bv_len; + + if (bvprv && cluster) { + if (sg[nsegs - 1].length + nbytes > q->max_segment_size) + goto new_segment; + + if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) + goto new_segment; + if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) + goto new_segment; + + sg[nsegs - 1].length += nbytes; + } else { +new_segment: + memset(&sg[nsegs],0,sizeof(struct scatterlist)); + sg[nsegs].page = bvec->bv_page; + sg[nsegs].length = nbytes; + sg[nsegs].offset = bvec->bv_offset; + + nsegs++; + } + bvprv = bvec; + } /* segments in bio */ + } /* bios in rq */ + + return nsegs; +} + +EXPORT_SYMBOL(blk_rq_map_sg); + +/* + * the standard queue merge functions, can be overridden with device + * specific ones if so desired + */ + +static inline int ll_new_mergeable(request_queue_t *q, + struct request *req, + struct bio *bio) +{ + int nr_phys_segs = bio_phys_segments(q, bio); + + if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { + req->flags |= REQ_NOMERGE; + if (req == q->last_merge) + q->last_merge = NULL; + return 0; + } + + /* + * A hw segment is just getting larger, bump just the phys + * counter. + */ + req->nr_phys_segments += nr_phys_segs; + return 1; +} + +static inline int ll_new_hw_segment(request_queue_t *q, + struct request *req, + struct bio *bio) +{ + int nr_hw_segs = bio_hw_segments(q, bio); + int nr_phys_segs = bio_phys_segments(q, bio); + + if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments + || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { + req->flags |= REQ_NOMERGE; + if (req == q->last_merge) + q->last_merge = NULL; + return 0; + } + + /* + * This will form the start of a new hw segment. Bump both + * counters. + */ + req->nr_hw_segments += nr_hw_segs; + req->nr_phys_segments += nr_phys_segs; + return 1; +} + +static int ll_back_merge_fn(request_queue_t *q, struct request *req, + struct bio *bio) +{ + int len; + + if (req->nr_sectors + bio_sectors(bio) > q->max_sectors) { + req->flags |= REQ_NOMERGE; + if (req == q->last_merge) + q->last_merge = NULL; + return 0; + } + if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID))) + blk_recount_segments(q, req->biotail); + if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) + blk_recount_segments(q, bio); + len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size; + if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) && + !BIOVEC_VIRT_OVERSIZE(len)) { + int mergeable = ll_new_mergeable(q, req, bio); + + if (mergeable) { + if (req->nr_hw_segments == 1) + req->bio->bi_hw_front_size = len; + if (bio->bi_hw_segments == 1) + bio->bi_hw_back_size = len; + } + return mergeable; + } + + return ll_new_hw_segment(q, req, bio); +} + +static int ll_front_merge_fn(request_queue_t *q, struct request *req, + struct bio *bio) +{ + int len; + + if (req->nr_sectors + bio_sectors(bio) > q->max_sectors) { + req->flags |= REQ_NOMERGE; + if (req == q->last_merge) + q->last_merge = NULL; + return 0; + } + len = bio->bi_hw_back_size + req->bio->bi_hw_front_size; + if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) + blk_recount_segments(q, bio); + if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID))) + blk_recount_segments(q, req->bio); + if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) && + !BIOVEC_VIRT_OVERSIZE(len)) { + int mergeable = ll_new_mergeable(q, req, bio); + + if (mergeable) { + if (bio->bi_hw_segments == 1) + bio->bi_hw_front_size = len; + if (req->nr_hw_segments == 1) + req->biotail->bi_hw_back_size = len; + } + return mergeable; + } + + return ll_new_hw_segment(q, req, bio); +} + +static int ll_merge_requests_fn(request_queue_t *q, struct request *req, + struct request *next) +{ + int total_phys_segments; + int total_hw_segments; + + /* + * First check if the either of the requests are re-queued + * requests. Can't merge them if they are. + */ + if (req->special || next->special) + return 0; + + /* + * Will it become too large? + */ + if ((req->nr_sectors + next->nr_sectors) > q->max_sectors) + return 0; + + total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; + if (blk_phys_contig_segment(q, req->biotail, next->bio)) + total_phys_segments--; + + if (total_phys_segments > q->max_phys_segments) + return 0; + + total_hw_segments = req->nr_hw_segments + next->nr_hw_segments; + if (blk_hw_contig_segment(q, req->biotail, next->bio)) { + int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size; + /* + * propagate the combined length to the end of the requests + */ + if (req->nr_hw_segments == 1) + req->bio->bi_hw_front_size = len; + if (next->nr_hw_segments == 1) + next->biotail->bi_hw_back_size = len; + total_hw_segments--; + } + + if (total_hw_segments > q->max_hw_segments) + return 0; + + /* Merge is OK... */ + req->nr_phys_segments = total_phys_segments; + req->nr_hw_segments = total_hw_segments; + return 1; +} + +/* + * "plug" the device if there are no outstanding requests: this will + * force the transfer to start only after we have put all the requests + * on the list. + * + * This is called with interrupts off and no requests on the queue and + * with the queue lock held. + */ +void blk_plug_device(request_queue_t *q) +{ + WARN_ON(!irqs_disabled()); + + /* + * don't plug a stopped queue, it must be paired with blk_start_queue() + * which will restart the queueing + */ + if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)) + return; + + if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) + mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); +} + +EXPORT_SYMBOL(blk_plug_device); + +/* + * remove the queue from the plugged list, if present. called with + * queue lock held and interrupts disabled. + */ +int blk_remove_plug(request_queue_t *q) +{ + WARN_ON(!irqs_disabled()); + + if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) + return 0; + + del_timer(&q->unplug_timer); + return 1; +} + +EXPORT_SYMBOL(blk_remove_plug); + +/* + * remove the plug and let it rip.. + */ +void __generic_unplug_device(request_queue_t *q) +{ + if (unlikely(test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags))) + return; + + if (!blk_remove_plug(q)) + return; + + q->request_fn(q); +} +EXPORT_SYMBOL(__generic_unplug_device); + +/** + * generic_unplug_device - fire a request queue + * @q: The &request_queue_t in question + * + * Description: + * Linux uses plugging to build bigger requests queues before letting + * the device have at them. If a queue is plugged, the I/O scheduler + * is still adding and merging requests on the queue. Once the queue + * gets unplugged, the request_fn defined for the queue is invoked and + * transfers started. + **/ +void generic_unplug_device(request_queue_t *q) +{ + spin_lock_irq(q->queue_lock); + __generic_unplug_device(q); + spin_unlock_irq(q->queue_lock); +} +EXPORT_SYMBOL(generic_unplug_device); + +static void blk_backing_dev_unplug(struct backing_dev_info *bdi, + struct page *page) +{ + request_queue_t *q = bdi->unplug_io_data; + + /* + * devices don't necessarily have an ->unplug_fn defined + */ + if (q->unplug_fn) + q->unplug_fn(q); +} + +static void blk_unplug_work(void *data) +{ + request_queue_t *q = data; + + q->unplug_fn(q); +} + +static void blk_unplug_timeout(unsigned long data) +{ + request_queue_t *q = (request_queue_t *)data; + + kblockd_schedule_work(&q->unplug_work); +} + +/** + * blk_start_queue - restart a previously stopped queue + * @q: The &request_queue_t in question + * + * Description: + * blk_start_queue() will clear the stop flag on the queue, and call + * the request_fn for the queue if it was in a stopped state when + * entered. Also see blk_stop_queue(). Queue lock must be held. + **/ +void blk_start_queue(request_queue_t *q) +{ + clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); + + /* + * one level of recursion is ok and is much faster than kicking + * the unplug handling + */ + if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { + q->request_fn(q); + clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags); + } else { + blk_plug_device(q); + kblockd_schedule_work(&q->unplug_work); + } +} + +EXPORT_SYMBOL(blk_start_queue); + +/** + * blk_stop_queue - stop a queue + * @q: The &request_queue_t in question + * + * Description: + * The Linux block layer assumes that a block driver will consume all + * entries on the request queue when the request_fn strategy is called. + * Often this will not happen, because of hardware limitations (queue + * depth settings). If a device driver gets a 'queue full' response, + * or if it simply chooses not to queue more I/O at one point, it can + * call this function to prevent the request_fn from being called until + * the driver has signalled it's ready to go again. This happens by calling + * blk_start_queue() to restart queue operations. Queue lock must be held. + **/ +void blk_stop_queue(request_queue_t *q) +{ + blk_remove_plug(q); + set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); +} +EXPORT_SYMBOL(blk_stop_queue); + +/** + * blk_sync_queue - cancel any pending callbacks on a queue + * @q: the queue + * + * Description: + * The block layer may perform asynchronous callback activity + * on a queue, such as calling the unplug function after a timeout. + * A block device may call blk_sync_queue to ensure that any + * such activity is cancelled, thus allowing it to release resources + * the the callbacks might use. The caller must already have made sure + * that its ->make_request_fn will not re-add plugging prior to calling + * this function. + * + */ +void blk_sync_queue(struct request_queue *q) +{ + del_timer_sync(&q->unplug_timer); + kblockd_flush(); +} +EXPORT_SYMBOL(blk_sync_queue); + +/** + * blk_run_queue - run a single device queue + * @q: The queue to run + */ +void blk_run_queue(struct request_queue *q) +{ + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + blk_remove_plug(q); + if (!elv_queue_empty(q)) + q->request_fn(q); + spin_unlock_irqrestore(q->queue_lock, flags); +} +EXPORT_SYMBOL(blk_run_queue); + +/** + * blk_cleanup_queue: - release a &request_queue_t when it is no longer needed + * @q: the request queue to be released + * + * Description: + * blk_cleanup_queue is the pair to blk_init_queue() or + * blk_queue_make_request(). It should be called when a request queue is + * being released; typically when a block device is being de-registered. + * Currently, its primary task it to free all the &struct request + * structures that were allocated to the queue and the queue itself. + * + * Caveat: + * Hopefully the low level driver will have finished any + * outstanding requests first... + **/ +void blk_cleanup_queue(request_queue_t * q) +{ + struct request_list *rl = &q->rq; + + if (!atomic_dec_and_test(&q->refcnt)) + return; + + if (q->elevator) + elevator_exit(q->elevator); + + blk_sync_queue(q); + + if (rl->rq_pool) + mempool_destroy(rl->rq_pool); + + if (q->queue_tags) + __blk_queue_free_tags(q); + + blk_queue_ordered(q, QUEUE_ORDERED_NONE); + + kmem_cache_free(requestq_cachep, q); +} + +EXPORT_SYMBOL(blk_cleanup_queue); + +static int blk_init_free_list(request_queue_t *q) +{ + struct request_list *rl = &q->rq; + + rl->count[READ] = rl->count[WRITE] = 0; + rl->starved[READ] = rl->starved[WRITE] = 0; + rl->elvpriv = 0; + init_waitqueue_head(&rl->wait[READ]); + init_waitqueue_head(&rl->wait[WRITE]); + + rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, + mempool_free_slab, request_cachep, q->node); + + if (!rl->rq_pool) + return -ENOMEM; + + return 0; +} + +static int __make_request(request_queue_t *, struct bio *); + +request_queue_t *blk_alloc_queue(gfp_t gfp_mask) +{ + return blk_alloc_queue_node(gfp_mask, -1); +} +EXPORT_SYMBOL(blk_alloc_queue); + +request_queue_t *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) +{ + request_queue_t *q; + + q = kmem_cache_alloc_node(requestq_cachep, gfp_mask, node_id); + if (!q) + return NULL; + + memset(q, 0, sizeof(*q)); + init_timer(&q->unplug_timer); + atomic_set(&q->refcnt, 1); + + q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; + q->backing_dev_info.unplug_io_data = q; + + return q; +} +EXPORT_SYMBOL(blk_alloc_queue_node); + +/** + * blk_init_queue - prepare a request queue for use with a block device + * @rfn: The function to be called to process requests that have been + * placed on the queue. + * @lock: Request queue spin lock + * + * Description: + * If a block device wishes to use the standard request handling procedures, + * which sorts requests and coalesces adjacent requests, then it must + * call blk_init_queue(). The function @rfn will be called when there + * are requests on the queue that need to be processed. If the device + * supports plugging, then @rfn may not be called immediately when requests + * are available on the queue, but may be called at some time later instead. + * Plugged queues are generally unplugged when a buffer belonging to one + * of the requests on the queue is needed, or due to memory pressure. + * + * @rfn is not required, or even expected, to remove all requests off the + * queue, but only as many as it can handle at a time. If it does leave + * requests on the queue, it is responsible for arranging that the requests + * get dealt with eventually. + * + * The queue spin lock must be held while manipulating the requests on the + * request queue. + * + * Function returns a pointer to the initialized request queue, or NULL if + * it didn't succeed. + * + * Note: + * blk_init_queue() must be paired with a blk_cleanup_queue() call + * when the block device is deactivated (such as at module unload). + **/ + +request_queue_t *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) +{ + return blk_init_queue_node(rfn, lock, -1); +} +EXPORT_SYMBOL(blk_init_queue); + +request_queue_t * +blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) +{ + request_queue_t *q = blk_alloc_queue_node(GFP_KERNEL, node_id); + + if (!q) + return NULL; + + q->node = node_id; + if (blk_init_free_list(q)) + goto out_init; + + /* + * if caller didn't supply a lock, they get per-queue locking with + * our embedded lock + */ + if (!lock) { + spin_lock_init(&q->__queue_lock); + lock = &q->__queue_lock; + } + + q->request_fn = rfn; + q->back_merge_fn = ll_back_merge_fn; + q->front_merge_fn = ll_front_merge_fn; + q->merge_requests_fn = ll_merge_requests_fn; + q->prep_rq_fn = NULL; + q->unplug_fn = generic_unplug_device; + q->queue_flags = (1 << QUEUE_FLAG_CLUSTER); + q->queue_lock = lock; + + blk_queue_segment_boundary(q, 0xffffffff); + + blk_queue_make_request(q, __make_request); + blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE); + + blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS); + blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS); + + /* + * all done + */ + if (!elevator_init(q, NULL)) { + blk_queue_congestion_threshold(q); + return q; + } + + blk_cleanup_queue(q); +out_init: + kmem_cache_free(requestq_cachep, q); + return NULL; +} +EXPORT_SYMBOL(blk_init_queue_node); + +int blk_get_queue(request_queue_t *q) +{ + if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { + atomic_inc(&q->refcnt); + return 0; + } + + return 1; +} + +EXPORT_SYMBOL(blk_get_queue); + +static inline void blk_free_request(request_queue_t *q, struct request *rq) +{ + if (rq->flags & REQ_ELVPRIV) + elv_put_request(q, rq); + mempool_free(rq, q->rq.rq_pool); +} + +static inline struct request * +blk_alloc_request(request_queue_t *q, int rw, struct bio *bio, + int priv, gfp_t gfp_mask) +{ + struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); + + if (!rq) + return NULL; + + /* + * first three bits are identical in rq->flags and bio->bi_rw, + * see bio.h and blkdev.h + */ + rq->flags = rw; + + if (priv) { + if (unlikely(elv_set_request(q, rq, bio, gfp_mask))) { + mempool_free(rq, q->rq.rq_pool); + return NULL; + } + rq->flags |= REQ_ELVPRIV; + } + + return rq; +} + +/* + * ioc_batching returns true if the ioc is a valid batching request and + * should be given priority access to a request. + */ +static inline int ioc_batching(request_queue_t *q, struct io_context *ioc) +{ + if (!ioc) + return 0; + + /* + * Make sure the process is able to allocate at least 1 request + * even if the batch times out, otherwise we could theoretically + * lose wakeups. + */ + return ioc->nr_batch_requests == q->nr_batching || + (ioc->nr_batch_requests > 0 + && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); +} + +/* + * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This + * will cause the process to be a "batcher" on all queues in the system. This + * is the behaviour we want though - once it gets a wakeup it should be given + * a nice run. + */ +static void ioc_set_batching(request_queue_t *q, struct io_context *ioc) +{ + if (!ioc || ioc_batching(q, ioc)) + return; + + ioc->nr_batch_requests = q->nr_batching; + ioc->last_waited = jiffies; +} + +static void __freed_request(request_queue_t *q, int rw) +{ + struct request_list *rl = &q->rq; + + if (rl->count[rw] < queue_congestion_off_threshold(q)) + clear_queue_congested(q, rw); + + if (rl->count[rw] + 1 <= q->nr_requests) { + if (waitqueue_active(&rl->wait[rw])) + wake_up(&rl->wait[rw]); + + blk_clear_queue_full(q, rw); + } +} + +/* + * A request has just been released. Account for it, update the full and + * congestion status, wake up any waiters. Called under q->queue_lock. + */ +static void freed_request(request_queue_t *q, int rw, int priv) +{ + struct request_list *rl = &q->rq; + + rl->count[rw]--; + if (priv) + rl->elvpriv--; + + __freed_request(q, rw); + + if (unlikely(rl->starved[rw ^ 1])) + __freed_request(q, rw ^ 1); +} + +#define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist) +/* + * Get a free request, queue_lock must be held. + * Returns NULL on failure, with queue_lock held. + * Returns !NULL on success, with queue_lock *not held*. + */ +static struct request *get_request(request_queue_t *q, int rw, struct bio *bio, + gfp_t gfp_mask) +{ + struct request *rq = NULL; + struct request_list *rl = &q->rq; + struct io_context *ioc = current_io_context(GFP_ATOMIC); + int priv; + + if (rl->count[rw]+1 >= q->nr_requests) { + /* + * The queue will fill after this allocation, so set it as + * full, and mark this process as "batching". This process + * will be allowed to complete a batch of requests, others + * will be blocked. + */ + if (!blk_queue_full(q, rw)) { + ioc_set_batching(q, ioc); + blk_set_queue_full(q, rw); + } + } + + switch (elv_may_queue(q, rw, bio)) { + case ELV_MQUEUE_NO: + goto rq_starved; + case ELV_MQUEUE_MAY: + break; + case ELV_MQUEUE_MUST: + goto get_rq; + } + + if (blk_queue_full(q, rw) && !ioc_batching(q, ioc)) { + /* + * The queue is full and the allocating process is not a + * "batcher", and not exempted by the IO scheduler + */ + goto out; + } + +get_rq: + /* + * Only allow batching queuers to allocate up to 50% over the defined + * limit of requests, otherwise we could have thousands of requests + * allocated with any setting of ->nr_requests + */ + if (rl->count[rw] >= (3 * q->nr_requests / 2)) + goto out; + + rl->count[rw]++; + rl->starved[rw] = 0; + if (rl->count[rw] >= queue_congestion_on_threshold(q)) + set_queue_congested(q, rw); + + priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); + if (priv) + rl->elvpriv++; + + spin_unlock_irq(q->queue_lock); + + rq = blk_alloc_request(q, rw, bio, priv, gfp_mask); + if (!rq) { + /* + * Allocation failed presumably due to memory. Undo anything + * we might have messed up. + * + * Allocating task should really be put onto the front of the + * wait queue, but this is pretty rare. + */ + spin_lock_irq(q->queue_lock); + freed_request(q, rw, priv); + + /* + * in the very unlikely event that allocation failed and no + * requests for this direction was pending, mark us starved + * so that freeing of a request in the other direction will + * notice us. another possible fix would be to split the + * rq mempool into READ and WRITE + */ +rq_starved: + if (unlikely(rl->count[rw] == 0)) + rl->starved[rw] = 1; + + goto out; + } + + if (ioc_batching(q, ioc)) + ioc->nr_batch_requests--; + + rq_init(q, rq); + rq->rl = rl; +out: + return rq; +} + +/* + * No available requests for this queue, unplug the device and wait for some + * requests to become available. + * + * Called with q->queue_lock held, and returns with it unlocked. + */ +static struct request *get_request_wait(request_queue_t *q, int rw, + struct bio *bio) +{ + struct request *rq; + + rq = get_request(q, rw, bio, GFP_NOIO); + while (!rq) { + DEFINE_WAIT(wait); + struct request_list *rl = &q->rq; + + prepare_to_wait_exclusive(&rl->wait[rw], &wait, + TASK_UNINTERRUPTIBLE); + + rq = get_request(q, rw, bio, GFP_NOIO); + + if (!rq) { + struct io_context *ioc; + + __generic_unplug_device(q); + spin_unlock_irq(q->queue_lock); + io_schedule(); + + /* + * After sleeping, we become a "batching" process and + * will be able to allocate at least one request, and + * up to a big batch of them for a small period time. + * See ioc_batching, ioc_set_batching + */ + ioc = current_io_context(GFP_NOIO); + ioc_set_batching(q, ioc); + + spin_lock_irq(q->queue_lock); + } + finish_wait(&rl->wait[rw], &wait); + } + + return rq; +} + +struct request *blk_get_request(request_queue_t *q, int rw, gfp_t gfp_mask) +{ + struct request *rq; + + BUG_ON(rw != READ && rw != WRITE); + + spin_lock_irq(q->queue_lock); + if (gfp_mask & __GFP_WAIT) { + rq = get_request_wait(q, rw, NULL); + } else { + rq = get_request(q, rw, NULL, gfp_mask); + if (!rq) + spin_unlock_irq(q->queue_lock); + } + /* q->queue_lock is unlocked at this point */ + + return rq; +} +EXPORT_SYMBOL(blk_get_request); + +/** + * blk_requeue_request - put a request back on queue + * @q: request queue where request should be inserted + * @rq: request to be inserted + * + * Description: + * Drivers often keep queueing requests until the hardware cannot accept + * more, when that condition happens we need to put the request back + * on the queue. Must be called with queue lock held. + */ +void blk_requeue_request(request_queue_t *q, struct request *rq) +{ + if (blk_rq_tagged(rq)) + blk_queue_end_tag(q, rq); + + elv_requeue_request(q, rq); +} + +EXPORT_SYMBOL(blk_requeue_request); + +/** + * blk_insert_request - insert a special request in to a request queue + * @q: request queue where request should be inserted + * @rq: request to be inserted + * @at_head: insert request at head or tail of queue + * @data: private data + * + * Description: + * Many block devices need to execute commands asynchronously, so they don't + * block the whole kernel from preemption during request execution. This is + * accomplished normally by inserting aritficial requests tagged as + * REQ_SPECIAL in to the corresponding request queue, and letting them be + * scheduled for actual execution by the request queue. + * + * We have the option of inserting the head or the tail of the queue. + * Typically we use the tail for new ioctls and so forth. We use the head + * of the queue for things like a QUEUE_FULL message from a device, or a + * host that is unable to accept a particular command. + */ +void blk_insert_request(request_queue_t *q, struct request *rq, + int at_head, void *data) +{ + int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; + unsigned long flags; + + /* + * tell I/O scheduler that this isn't a regular read/write (ie it + * must not attempt merges on this) and that it acts as a soft + * barrier + */ + rq->flags |= REQ_SPECIAL | REQ_SOFTBARRIER; + + rq->special = data; + + spin_lock_irqsave(q->queue_lock, flags); + + /* + * If command is tagged, release the tag + */ + if (blk_rq_tagged(rq)) + blk_queue_end_tag(q, rq); + + drive_stat_acct(rq, rq->nr_sectors, 1); + __elv_add_request(q, rq, where, 0); + + if (blk_queue_plugged(q)) + __generic_unplug_device(q); + else + q->request_fn(q); + spin_unlock_irqrestore(q->queue_lock, flags); +} + +EXPORT_SYMBOL(blk_insert_request); + +/** + * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage + * @q: request queue where request should be inserted + * @rq: request structure to fill + * @ubuf: the user buffer + * @len: length of user data + * + * Description: + * Data will be mapped directly for zero copy io, if possible. Otherwise + * a kernel bounce buffer is used. + * + * A matching blk_rq_unmap_user() must be issued at the end of io, while + * still in process context. + * + * Note: The mapped bio may need to be bounced through blk_queue_bounce() + * before being submitted to the device, as pages mapped may be out of + * reach. It's the callers responsibility to make sure this happens. The + * original bio must be passed back in to blk_rq_unmap_user() for proper + * unmapping. + */ +int blk_rq_map_user(request_queue_t *q, struct request *rq, void __user *ubuf, + unsigned int len) +{ + unsigned long uaddr; + struct bio *bio; + int reading; + + if (len > (q->max_sectors << 9)) + return -EINVAL; + if (!len || !ubuf) + return -EINVAL; + + reading = rq_data_dir(rq) == READ; + + /* + * if alignment requirement is satisfied, map in user pages for + * direct dma. else, set up kernel bounce buffers + */ + uaddr = (unsigned long) ubuf; + if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q))) + bio = bio_map_user(q, NULL, uaddr, len, reading); + else + bio = bio_copy_user(q, uaddr, len, reading); + + if (!IS_ERR(bio)) { + rq->bio = rq->biotail = bio; + blk_rq_bio_prep(q, rq, bio); + + rq->buffer = rq->data = NULL; + rq->data_len = len; + return 0; + } + + /* + * bio is the err-ptr + */ + return PTR_ERR(bio); +} + +EXPORT_SYMBOL(blk_rq_map_user); + +/** + * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage + * @q: request queue where request should be inserted + * @rq: request to map data to + * @iov: pointer to the iovec + * @iov_count: number of elements in the iovec + * + * Description: + * Data will be mapped directly for zero copy io, if possible. Otherwise + * a kernel bounce buffer is used. + * + * A matching blk_rq_unmap_user() must be issued at the end of io, while + * still in process context. + * + * Note: The mapped bio may need to be bounced through blk_queue_bounce() + * before being submitted to the device, as pages mapped may be out of + * reach. It's the callers responsibility to make sure this happens. The + * original bio must be passed back in to blk_rq_unmap_user() for proper + * unmapping. + */ +int blk_rq_map_user_iov(request_queue_t *q, struct request *rq, + struct sg_iovec *iov, int iov_count) +{ + struct bio *bio; + + if (!iov || iov_count <= 0) + return -EINVAL; + + /* we don't allow misaligned data like bio_map_user() does. If the + * user is using sg, they're expected to know the alignment constraints + * and respect them accordingly */ + bio = bio_map_user_iov(q, NULL, iov, iov_count, rq_data_dir(rq)== READ); + if (IS_ERR(bio)) + return PTR_ERR(bio); + + rq->bio = rq->biotail = bio; + blk_rq_bio_prep(q, rq, bio); + rq->buffer = rq->data = NULL; + rq->data_len = bio->bi_size; + return 0; +} + +EXPORT_SYMBOL(blk_rq_map_user_iov); + +/** + * blk_rq_unmap_user - unmap a request with user data + * @bio: bio to be unmapped + * @ulen: length of user buffer + * + * Description: + * Unmap a bio previously mapped by blk_rq_map_user(). + */ +int blk_rq_unmap_user(struct bio *bio, unsigned int ulen) +{ + int ret = 0; + + if (bio) { + if (bio_flagged(bio, BIO_USER_MAPPED)) + bio_unmap_user(bio); + else + ret = bio_uncopy_user(bio); + } + + return 0; +} + +EXPORT_SYMBOL(blk_rq_unmap_user); + +/** + * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage + * @q: request queue where request should be inserted + * @rq: request to fill + * @kbuf: the kernel buffer + * @len: length of user data + * @gfp_mask: memory allocation flags + */ +int blk_rq_map_kern(request_queue_t *q, struct request *rq, void *kbuf, + unsigned int len, gfp_t gfp_mask) +{ + struct bio *bio; + + if (len > (q->max_sectors << 9)) + return -EINVAL; + if (!len || !kbuf) + return -EINVAL; + + bio = bio_map_kern(q, kbuf, len, gfp_mask); + if (IS_ERR(bio)) + return PTR_ERR(bio); + + if (rq_data_dir(rq) == WRITE) + bio->bi_rw |= (1 << BIO_RW); + + rq->bio = rq->biotail = bio; + blk_rq_bio_prep(q, rq, bio); + + rq->buffer = rq->data = NULL; + rq->data_len = len; + return 0; +} + +EXPORT_SYMBOL(blk_rq_map_kern); + +/** + * blk_execute_rq_nowait - insert a request into queue for execution + * @q: queue to insert the request in + * @bd_disk: matching gendisk + * @rq: request to insert + * @at_head: insert request at head or tail of queue + * @done: I/O completion handler + * + * Description: + * Insert a fully prepared request at the back of the io scheduler queue + * for execution. Don't wait for completion. + */ +void blk_execute_rq_nowait(request_queue_t *q, struct gendisk *bd_disk, + struct request *rq, int at_head, + void (*done)(struct request *)) +{ + int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; + + rq->rq_disk = bd_disk; + rq->flags |= REQ_NOMERGE; + rq->end_io = done; + elv_add_request(q, rq, where, 1); + generic_unplug_device(q); +} + +/** + * blk_execute_rq - insert a request into queue for execution + * @q: queue to insert the request in + * @bd_disk: matching gendisk + * @rq: request to insert + * @at_head: insert request at head or tail of queue + * + * Description: + * Insert a fully prepared request at the back of the io scheduler queue + * for execution and wait for completion. + */ +int blk_execute_rq(request_queue_t *q, struct gendisk *bd_disk, + struct request *rq, int at_head) +{ + DECLARE_COMPLETION(wait); + char sense[SCSI_SENSE_BUFFERSIZE]; + int err = 0; + + /* + * we need an extra reference to the request, so we can look at + * it after io completion + */ + rq->ref_count++; + + if (!rq->sense) { + memset(sense, 0, sizeof(sense)); + rq->sense = sense; + rq->sense_len = 0; + } + + rq->waiting = &wait; + blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq); + wait_for_completion(&wait); + rq->waiting = NULL; + + if (rq->errors) + err = -EIO; + + return err; +} + +EXPORT_SYMBOL(blk_execute_rq); + +/** + * blkdev_issue_flush - queue a flush + * @bdev: blockdev to issue flush for + * @error_sector: error sector + * + * Description: + * Issue a flush for the block device in question. Caller can supply + * room for storing the error offset in case of a flush error, if they + * wish to. Caller must run wait_for_completion() on its own. + */ +int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector) +{ + request_queue_t *q; + + if (bdev->bd_disk == NULL) + return -ENXIO; + + q = bdev_get_queue(bdev); + if (!q) + return -ENXIO; + if (!q->issue_flush_fn) + return -EOPNOTSUPP; + + return q->issue_flush_fn(q, bdev->bd_disk, error_sector); +} + +EXPORT_SYMBOL(blkdev_issue_flush); + +static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io) +{ + int rw = rq_data_dir(rq); + + if (!blk_fs_request(rq) || !rq->rq_disk) + return; + + if (!new_io) { + __disk_stat_inc(rq->rq_disk, merges[rw]); + } else { + disk_round_stats(rq->rq_disk); + rq->rq_disk->in_flight++; + } +} + +/* + * add-request adds a request to the linked list. + * queue lock is held and interrupts disabled, as we muck with the + * request queue list. + */ +static inline void add_request(request_queue_t * q, struct request * req) +{ + drive_stat_acct(req, req->nr_sectors, 1); + + if (q->activity_fn) + q->activity_fn(q->activity_data, rq_data_dir(req)); + + /* + * elevator indicated where it wants this request to be + * inserted at elevator_merge time + */ + __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0); +} + +/* + * disk_round_stats() - Round off the performance stats on a struct + * disk_stats. + * + * The average IO queue length and utilisation statistics are maintained + * by observing the current state of the queue length and the amount of + * time it has been in this state for. + * + * Normally, that accounting is done on IO completion, but that can result + * in more than a second's worth of IO being accounted for within any one + * second, leading to >100% utilisation. To deal with that, we call this + * function to do a round-off before returning the results when reading + * /proc/diskstats. This accounts immediately for all queue usage up to + * the current jiffies and restarts the counters again. + */ +void disk_round_stats(struct gendisk *disk) +{ + unsigned long now = jiffies; + + if (now == disk->stamp) + return; + + if (disk->in_flight) { + __disk_stat_add(disk, time_in_queue, + disk->in_flight * (now - disk->stamp)); + __disk_stat_add(disk, io_ticks, (now - disk->stamp)); + } + disk->stamp = now; +} + +/* + * queue lock must be held + */ +static void __blk_put_request(request_queue_t *q, struct request *req) +{ + struct request_list *rl = req->rl; + + if (unlikely(!q)) + return; + if (unlikely(--req->ref_count)) + return; + + elv_completed_request(q, req); + + req->rq_status = RQ_INACTIVE; + req->rl = NULL; + + /* + * Request may not have originated from ll_rw_blk. if not, + * it didn't come out of our reserved rq pools + */ + if (rl) { + int rw = rq_data_dir(req); + int priv = req->flags & REQ_ELVPRIV; + + BUG_ON(!list_empty(&req->queuelist)); + + blk_free_request(q, req); + freed_request(q, rw, priv); + } +} + +void blk_put_request(struct request *req) +{ + unsigned long flags; + request_queue_t *q = req->q; + + /* + * Gee, IDE calls in w/ NULL q. Fix IDE and remove the + * following if (q) test. + */ + if (q) { + spin_lock_irqsave(q->queue_lock, flags); + __blk_put_request(q, req); + spin_unlock_irqrestore(q->queue_lock, flags); + } +} + +EXPORT_SYMBOL(blk_put_request); + +/** + * blk_end_sync_rq - executes a completion event on a request + * @rq: request to complete + */ +void blk_end_sync_rq(struct request *rq) +{ + struct completion *waiting = rq->waiting; + + rq->waiting = NULL; + __blk_put_request(rq->q, rq); + + /* + * complete last, if this is a stack request the process (and thus + * the rq pointer) could be invalid right after this complete() + */ + complete(waiting); +} +EXPORT_SYMBOL(blk_end_sync_rq); + +/** + * blk_congestion_wait - wait for a queue to become uncongested + * @rw: READ or WRITE + * @timeout: timeout in jiffies + * + * Waits for up to @timeout jiffies for a queue (any queue) to exit congestion. + * If no queues are congested then just wait for the next request to be + * returned. + */ +long blk_congestion_wait(int rw, long timeout) +{ + long ret; + DEFINE_WAIT(wait); + wait_queue_head_t *wqh = &congestion_wqh[rw]; + + prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); + ret = io_schedule_timeout(timeout); + finish_wait(wqh, &wait); + return ret; +} + +EXPORT_SYMBOL(blk_congestion_wait); + +/* + * Has to be called with the request spinlock acquired + */ +static int attempt_merge(request_queue_t *q, struct request *req, + struct request *next) +{ + if (!rq_mergeable(req) || !rq_mergeable(next)) + return 0; + + /* + * not contigious + */ + if (req->sector + req->nr_sectors != next->sector) + return 0; + + if (rq_data_dir(req) != rq_data_dir(next) + || req->rq_disk != next->rq_disk + || next->waiting || next->special) + return 0; + + /* + * If we are allowed to merge, then append bio list + * from next to rq and release next. merge_requests_fn + * will have updated segment counts, update sector + * counts here. + */ + if (!q->merge_requests_fn(q, req, next)) + return 0; + + /* + * At this point we have either done a back merge + * or front merge. We need the smaller start_time of + * the merged requests to be the current request + * for accounting purposes. + */ + if (time_after(req->start_time, next->start_time)) + req->start_time = next->start_time; + + req->biotail->bi_next = next->bio; + req->biotail = next->biotail; + + req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors; + + elv_merge_requests(q, req, next); + + if (req->rq_disk) { + disk_round_stats(req->rq_disk); + req->rq_disk->in_flight--; + } + + req->ioprio = ioprio_best(req->ioprio, next->ioprio); + + __blk_put_request(q, next); + return 1; +} + +static inline int attempt_back_merge(request_queue_t *q, struct request *rq) +{ + struct request *next = elv_latter_request(q, rq); + + if (next) + return attempt_merge(q, rq, next); + + return 0; +} + +static inline int attempt_front_merge(request_queue_t *q, struct request *rq) +{ + struct request *prev = elv_former_request(q, rq); + + if (prev) + return attempt_merge(q, prev, rq); + + return 0; +} + +/** + * blk_attempt_remerge - attempt to remerge active head with next request + * @q: The &request_queue_t belonging to the device + * @rq: The head request (usually) + * + * Description: + * For head-active devices, the queue can easily be unplugged so quickly + * that proper merging is not done on the front request. This may hurt + * performance greatly for some devices. The block layer cannot safely + * do merging on that first request for these queues, but the driver can + * call this function and make it happen any way. Only the driver knows + * when it is safe to do so. + **/ +void blk_attempt_remerge(request_queue_t *q, struct request *rq) +{ + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + attempt_back_merge(q, rq); + spin_unlock_irqrestore(q->queue_lock, flags); +} + +EXPORT_SYMBOL(blk_attempt_remerge); + +static int __make_request(request_queue_t *q, struct bio *bio) +{ + struct request *req; + int el_ret, rw, nr_sectors, cur_nr_sectors, barrier, err, sync; + unsigned short prio; + sector_t sector; + + sector = bio->bi_sector; + nr_sectors = bio_sectors(bio); + cur_nr_sectors = bio_cur_sectors(bio); + prio = bio_prio(bio); + + rw = bio_data_dir(bio); + sync = bio_sync(bio); + + /* + * low level driver can indicate that it wants pages above a + * certain limit bounced to low memory (ie for highmem, or even + * ISA dma in theory) + */ + blk_queue_bounce(q, &bio); + + spin_lock_prefetch(q->queue_lock); + + barrier = bio_barrier(bio); + if (unlikely(barrier) && (q->ordered == QUEUE_ORDERED_NONE)) { + err = -EOPNOTSUPP; + goto end_io; + } + + spin_lock_irq(q->queue_lock); + + if (unlikely(barrier) || elv_queue_empty(q)) + goto get_rq; + + el_ret = elv_merge(q, &req, bio); + switch (el_ret) { + case ELEVATOR_BACK_MERGE: + BUG_ON(!rq_mergeable(req)); + + if (!q->back_merge_fn(q, req, bio)) + break; + + req->biotail->bi_next = bio; + req->biotail = bio; + req->nr_sectors = req->hard_nr_sectors += nr_sectors; + req->ioprio = ioprio_best(req->ioprio, prio); + drive_stat_acct(req, nr_sectors, 0); + if (!attempt_back_merge(q, req)) + elv_merged_request(q, req); + goto out; + + case ELEVATOR_FRONT_MERGE: + BUG_ON(!rq_mergeable(req)); + + if (!q->front_merge_fn(q, req, bio)) + break; + + bio->bi_next = req->bio; + req->bio = bio; + + /* + * may not be valid. if the low level driver said + * it didn't need a bounce buffer then it better + * not touch req->buffer either... + */ + req->buffer = bio_data(bio); + req->current_nr_sectors = cur_nr_sectors; + req->hard_cur_sectors = cur_nr_sectors; + req->sector = req->hard_sector = sector; + req->nr_sectors = req->hard_nr_sectors += nr_sectors; + req->ioprio = ioprio_best(req->ioprio, prio); + drive_stat_acct(req, nr_sectors, 0); + if (!attempt_front_merge(q, req)) + elv_merged_request(q, req); + goto out; + + /* ELV_NO_MERGE: elevator says don't/can't merge. */ + default: + ; + } + +get_rq: + /* + * Grab a free request. This is might sleep but can not fail. + * Returns with the queue unlocked. + */ + req = get_request_wait(q, rw, bio); + + /* + * After dropping the lock and possibly sleeping here, our request + * may now be mergeable after it had proven unmergeable (above). + * We don't worry about that case for efficiency. It won't happen + * often, and the elevators are able to handle it. + */ + + req->flags |= REQ_CMD; + + /* + * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST) + */ + if (bio_rw_ahead(bio) || bio_failfast(bio)) + req->flags |= REQ_FAILFAST; + + /* + * REQ_BARRIER implies no merging, but lets make it explicit + */ + if (unlikely(barrier)) + req->flags |= (REQ_HARDBARRIER | REQ_NOMERGE); + + req->errors = 0; + req->hard_sector = req->sector = sector; + req->hard_nr_sectors = req->nr_sectors = nr_sectors; + req->current_nr_sectors = req->hard_cur_sectors = cur_nr_sectors; + req->nr_phys_segments = bio_phys_segments(q, bio); + req->nr_hw_segments = bio_hw_segments(q, bio); + req->buffer = bio_data(bio); /* see ->buffer comment above */ + req->waiting = NULL; + req->bio = req->biotail = bio; + req->ioprio = prio; + req->rq_disk = bio->bi_bdev->bd_disk; + req->start_time = jiffies; + + spin_lock_irq(q->queue_lock); + if (elv_queue_empty(q)) + blk_plug_device(q); + add_request(q, req); +out: + if (sync) + __generic_unplug_device(q); + + spin_unlock_irq(q->queue_lock); + return 0; + +end_io: + bio_endio(bio, nr_sectors << 9, err); + return 0; +} + +/* + * If bio->bi_dev is a partition, remap the location + */ +static inline void blk_partition_remap(struct bio *bio) +{ + struct block_device *bdev = bio->bi_bdev; + + if (bdev != bdev->bd_contains) { + struct hd_struct *p = bdev->bd_part; + const int rw = bio_data_dir(bio); + + p->sectors[rw] += bio_sectors(bio); + p->ios[rw]++; + + bio->bi_sector += p->start_sect; + bio->bi_bdev = bdev->bd_contains; + } +} + +static void handle_bad_sector(struct bio *bio) +{ + char b[BDEVNAME_SIZE]; + + printk(KERN_INFO "attempt to access beyond end of device\n"); + printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n", + bdevname(bio->bi_bdev, b), + bio->bi_rw, + (unsigned long long)bio->bi_sector + bio_sectors(bio), + (long long)(bio->bi_bdev->bd_inode->i_size >> 9)); + + set_bit(BIO_EOF, &bio->bi_flags); +} + +/** + * generic_make_request: hand a buffer to its device driver for I/O + * @bio: The bio describing the location in memory and on the device. + * + * generic_make_request() is used to make I/O requests of block + * devices. It is passed a &struct bio, which describes the I/O that needs + * to be done. + * + * generic_make_request() does not return any status. The + * success/failure status of the request, along with notification of + * completion, is delivered asynchronously through the bio->bi_end_io + * function described (one day) else where. + * + * The caller of generic_make_request must make sure that bi_io_vec + * are set to describe the memory buffer, and that bi_dev and bi_sector are + * set to describe the device address, and the + * bi_end_io and optionally bi_private are set to describe how + * completion notification should be signaled. + * + * generic_make_request and the drivers it calls may use bi_next if this + * bio happens to be merged with someone else, and may change bi_dev and + * bi_sector for remaps as it sees fit. So the values of these fields + * should NOT be depended on after the call to generic_make_request. + */ +void generic_make_request(struct bio *bio) +{ + request_queue_t *q; + sector_t maxsector; + int ret, nr_sectors = bio_sectors(bio); + + might_sleep(); + /* Test device or partition size, when known. */ + maxsector = bio->bi_bdev->bd_inode->i_size >> 9; + if (maxsector) { + sector_t sector = bio->bi_sector; + + if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { + /* + * This may well happen - the kernel calls bread() + * without checking the size of the device, e.g., when + * mounting a device. + */ + handle_bad_sector(bio); + goto end_io; + } + } + + /* + * Resolve the mapping until finished. (drivers are + * still free to implement/resolve their own stacking + * by explicitly returning 0) + * + * NOTE: we don't repeat the blk_size check for each new device. + * Stacking drivers are expected to know what they are doing. + */ + do { + char b[BDEVNAME_SIZE]; + + q = bdev_get_queue(bio->bi_bdev); + if (!q) { + printk(KERN_ERR + "generic_make_request: Trying to access " + "nonexistent block-device %s (%Lu)\n", + bdevname(bio->bi_bdev, b), + (long long) bio->bi_sector); +end_io: + bio_endio(bio, bio->bi_size, -EIO); + break; + } + + if (unlikely(bio_sectors(bio) > q->max_hw_sectors)) { + printk("bio too big device %s (%u > %u)\n", + bdevname(bio->bi_bdev, b), + bio_sectors(bio), + q->max_hw_sectors); + goto end_io; + } + + if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) + goto end_io; + + /* + * If this device has partitions, remap block n + * of partition p to block n+start(p) of the disk. + */ + blk_partition_remap(bio); + + ret = q->make_request_fn(q, bio); + } while (ret); +} + +EXPORT_SYMBOL(generic_make_request); + +/** + * submit_bio: submit a bio to the block device layer for I/O + * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) + * @bio: The &struct bio which describes the I/O + * + * submit_bio() is very similar in purpose to generic_make_request(), and + * uses that function to do most of the work. Both are fairly rough + * interfaces, @bio must be presetup and ready for I/O. + * + */ +void submit_bio(int rw, struct bio *bio) +{ + int count = bio_sectors(bio); + + BIO_BUG_ON(!bio->bi_size); + BIO_BUG_ON(!bio->bi_io_vec); + bio->bi_rw |= rw; + if (rw & WRITE) + mod_page_state(pgpgout, count); + else + mod_page_state(pgpgin, count); + + if (unlikely(block_dump)) { + char b[BDEVNAME_SIZE]; + printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n", + current->comm, current->pid, + (rw & WRITE) ? "WRITE" : "READ", + (unsigned long long)bio->bi_sector, + bdevname(bio->bi_bdev,b)); + } + + generic_make_request(bio); +} + +EXPORT_SYMBOL(submit_bio); + +static void blk_recalc_rq_segments(struct request *rq) +{ + struct bio *bio, *prevbio = NULL; + int nr_phys_segs, nr_hw_segs; + unsigned int phys_size, hw_size; + request_queue_t *q = rq->q; + + if (!rq->bio) + return; + + phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0; + rq_for_each_bio(bio, rq) { + /* Force bio hw/phys segs to be recalculated. */ + bio->bi_flags &= ~(1 << BIO_SEG_VALID); + + nr_phys_segs += bio_phys_segments(q, bio); + nr_hw_segs += bio_hw_segments(q, bio); + if (prevbio) { + int pseg = phys_size + prevbio->bi_size + bio->bi_size; + int hseg = hw_size + prevbio->bi_size + bio->bi_size; + + if (blk_phys_contig_segment(q, prevbio, bio) && + pseg <= q->max_segment_size) { + nr_phys_segs--; + phys_size += prevbio->bi_size + bio->bi_size; + } else + phys_size = 0; + + if (blk_hw_contig_segment(q, prevbio, bio) && + hseg <= q->max_segment_size) { + nr_hw_segs--; + hw_size += prevbio->bi_size + bio->bi_size; + } else + hw_size = 0; + } + prevbio = bio; + } + + rq->nr_phys_segments = nr_phys_segs; + rq->nr_hw_segments = nr_hw_segs; +} + +static void blk_recalc_rq_sectors(struct request *rq, int nsect) +{ + if (blk_fs_request(rq)) { + rq->hard_sector += nsect; + rq->hard_nr_sectors -= nsect; + + /* + * Move the I/O submission pointers ahead if required. + */ + if ((rq->nr_sectors >= rq->hard_nr_sectors) && + (rq->sector <= rq->hard_sector)) { + rq->sector = rq->hard_sector; + rq->nr_sectors = rq->hard_nr_sectors; + rq->hard_cur_sectors = bio_cur_sectors(rq->bio); + rq->current_nr_sectors = rq->hard_cur_sectors; + rq->buffer = bio_data(rq->bio); + } + + /* + * if total number of sectors is less than the first segment + * size, something has gone terribly wrong + */ + if (rq->nr_sectors < rq->current_nr_sectors) { + printk("blk: request botched\n"); + rq->nr_sectors = rq->current_nr_sectors; + } + } +} + +static int __end_that_request_first(struct request *req, int uptodate, + int nr_bytes) +{ + int total_bytes, bio_nbytes, error, next_idx = 0; + struct bio *bio; + + /* + * extend uptodate bool to allow < 0 value to be direct io error + */ + error = 0; + if (end_io_error(uptodate)) + error = !uptodate ? -EIO : uptodate; + + /* + * for a REQ_BLOCK_PC request, we want to carry any eventual + * sense key with us all the way through + */ + if (!blk_pc_request(req)) + req->errors = 0; + + if (!uptodate) { + if (blk_fs_request(req) && !(req->flags & REQ_QUIET)) + printk("end_request: I/O error, dev %s, sector %llu\n", + req->rq_disk ? req->rq_disk->disk_name : "?", + (unsigned long long)req->sector); + } + + if (blk_fs_request(req) && req->rq_disk) { + const int rw = rq_data_dir(req); + + __disk_stat_add(req->rq_disk, sectors[rw], nr_bytes >> 9); + } + + total_bytes = bio_nbytes = 0; + while ((bio = req->bio) != NULL) { + int nbytes; + + if (nr_bytes >= bio->bi_size) { + req->bio = bio->bi_next; + nbytes = bio->bi_size; + bio_endio(bio, nbytes, error); + next_idx = 0; + bio_nbytes = 0; + } else { + int idx = bio->bi_idx + next_idx; + + if (unlikely(bio->bi_idx >= bio->bi_vcnt)) { + blk_dump_rq_flags(req, "__end_that"); + printk("%s: bio idx %d >= vcnt %d\n", + __FUNCTION__, + bio->bi_idx, bio->bi_vcnt); + break; + } + + nbytes = bio_iovec_idx(bio, idx)->bv_len; + BIO_BUG_ON(nbytes > bio->bi_size); + + /* + * not a complete bvec done + */ + if (unlikely(nbytes > nr_bytes)) { + bio_nbytes += nr_bytes; + total_bytes += nr_bytes; + break; + } + + /* + * advance to the next vector + */ + next_idx++; + bio_nbytes += nbytes; + } + + total_bytes += nbytes; + nr_bytes -= nbytes; + + if ((bio = req->bio)) { + /* + * end more in this run, or just return 'not-done' + */ + if (unlikely(nr_bytes <= 0)) + break; + } + } + + /* + * completely done + */ + if (!req->bio) + return 0; + + /* + * if the request wasn't completed, update state + */ + if (bio_nbytes) { + bio_endio(bio, bio_nbytes, error); + bio->bi_idx += next_idx; + bio_iovec(bio)->bv_offset += nr_bytes; + bio_iovec(bio)->bv_len -= nr_bytes; + } + + blk_recalc_rq_sectors(req, total_bytes >> 9); + blk_recalc_rq_segments(req); + return 1; +} + +/** + * end_that_request_first - end I/O on a request + * @req: the request being processed + * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error + * @nr_sectors: number of sectors to end I/O on + * + * Description: + * Ends I/O on a number of sectors attached to @req, and sets it up + * for the next range of segments (if any) in the cluster. + * + * Return: + * 0 - we are done with this request, call end_that_request_last() + * 1 - still buffers pending for this request + **/ +int end_that_request_first(struct request *req, int uptodate, int nr_sectors) +{ + return __end_that_request_first(req, uptodate, nr_sectors << 9); +} + +EXPORT_SYMBOL(end_that_request_first); + +/** + * end_that_request_chunk - end I/O on a request + * @req: the request being processed + * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error + * @nr_bytes: number of bytes to complete + * + * Description: + * Ends I/O on a number of bytes attached to @req, and sets it up + * for the next range of segments (if any). Like end_that_request_first(), + * but deals with bytes instead of sectors. + * + * Return: + * 0 - we are done with this request, call end_that_request_last() + * 1 - still buffers pending for this request + **/ +int end_that_request_chunk(struct request *req, int uptodate, int nr_bytes) +{ + return __end_that_request_first(req, uptodate, nr_bytes); +} + +EXPORT_SYMBOL(end_that_request_chunk); + +/* + * queue lock must be held + */ +void end_that_request_last(struct request *req) +{ + struct gendisk *disk = req->rq_disk; + + if (unlikely(laptop_mode) && blk_fs_request(req)) + laptop_io_completion(); + + if (disk && blk_fs_request(req)) { + unsigned long duration = jiffies - req->start_time; + const int rw = rq_data_dir(req); + + __disk_stat_inc(disk, ios[rw]); + __disk_stat_add(disk, ticks[rw], duration); + disk_round_stats(disk); + disk->in_flight--; + } + if (req->end_io) + req->end_io(req); + else + __blk_put_request(req->q, req); +} + +EXPORT_SYMBOL(end_that_request_last); + +void end_request(struct request *req, int uptodate) +{ + if (!end_that_request_first(req, uptodate, req->hard_cur_sectors)) { + add_disk_randomness(req->rq_disk); + blkdev_dequeue_request(req); + end_that_request_last(req); + } +} + +EXPORT_SYMBOL(end_request); + +void blk_rq_bio_prep(request_queue_t *q, struct request *rq, struct bio *bio) +{ + /* first three bits are identical in rq->flags and bio->bi_rw */ + rq->flags |= (bio->bi_rw & 7); + + rq->nr_phys_segments = bio_phys_segments(q, bio); + rq->nr_hw_segments = bio_hw_segments(q, bio); + rq->current_nr_sectors = bio_cur_sectors(bio); + rq->hard_cur_sectors = rq->current_nr_sectors; + rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio); + rq->buffer = bio_data(bio); + + rq->bio = rq->biotail = bio; +} + +EXPORT_SYMBOL(blk_rq_bio_prep); + +int kblockd_schedule_work(struct work_struct *work) +{ + return queue_work(kblockd_workqueue, work); +} + +EXPORT_SYMBOL(kblockd_schedule_work); + +void kblockd_flush(void) +{ + flush_workqueue(kblockd_workqueue); +} +EXPORT_SYMBOL(kblockd_flush); + +int __init blk_dev_init(void) +{ + kblockd_workqueue = create_workqueue("kblockd"); + if (!kblockd_workqueue) + panic("Failed to create kblockd\n"); + + request_cachep = kmem_cache_create("blkdev_requests", + sizeof(struct request), 0, SLAB_PANIC, NULL, NULL); + + requestq_cachep = kmem_cache_create("blkdev_queue", + sizeof(request_queue_t), 0, SLAB_PANIC, NULL, NULL); + + iocontext_cachep = kmem_cache_create("blkdev_ioc", + sizeof(struct io_context), 0, SLAB_PANIC, NULL, NULL); + + blk_max_low_pfn = max_low_pfn; + blk_max_pfn = max_pfn; + + return 0; +} + +/* + * IO Context helper functions + */ +void put_io_context(struct io_context *ioc) +{ + if (ioc == NULL) + return; + + BUG_ON(atomic_read(&ioc->refcount) == 0); + + if (atomic_dec_and_test(&ioc->refcount)) { + if (ioc->aic && ioc->aic->dtor) + ioc->aic->dtor(ioc->aic); + if (ioc->cic && ioc->cic->dtor) + ioc->cic->dtor(ioc->cic); + + kmem_cache_free(iocontext_cachep, ioc); + } +} +EXPORT_SYMBOL(put_io_context); + +/* Called by the exitting task */ +void exit_io_context(void) +{ + unsigned long flags; + struct io_context *ioc; + + local_irq_save(flags); + task_lock(current); + ioc = current->io_context; + current->io_context = NULL; + ioc->task = NULL; + task_unlock(current); + local_irq_restore(flags); + + if (ioc->aic && ioc->aic->exit) + ioc->aic->exit(ioc->aic); + if (ioc->cic && ioc->cic->exit) + ioc->cic->exit(ioc->cic); + + put_io_context(ioc); +} + +/* + * If the current task has no IO context then create one and initialise it. + * Otherwise, return its existing IO context. + * + * This returned IO context doesn't have a specifically elevated refcount, + * but since the current task itself holds a reference, the context can be + * used in general code, so long as it stays within `current` context. + */ +struct io_context *current_io_context(gfp_t gfp_flags) +{ + struct task_struct *tsk = current; + struct io_context *ret; + + ret = tsk->io_context; + if (likely(ret)) + return ret; + + ret = kmem_cache_alloc(iocontext_cachep, gfp_flags); + if (ret) { + atomic_set(&ret->refcount, 1); + ret->task = current; + ret->set_ioprio = NULL; + ret->last_waited = jiffies; /* doesn't matter... */ + ret->nr_batch_requests = 0; /* because this is 0 */ + ret->aic = NULL; + ret->cic = NULL; + tsk->io_context = ret; + } + + return ret; +} +EXPORT_SYMBOL(current_io_context); + +/* + * If the current task has no IO context then create one and initialise it. + * If it does have a context, take a ref on it. + * + * This is always called in the context of the task which submitted the I/O. + */ +struct io_context *get_io_context(gfp_t gfp_flags) +{ + struct io_context *ret; + ret = current_io_context(gfp_flags); + if (likely(ret)) + atomic_inc(&ret->refcount); + return ret; +} +EXPORT_SYMBOL(get_io_context); + +void copy_io_context(struct io_context **pdst, struct io_context **psrc) +{ + struct io_context *src = *psrc; + struct io_context *dst = *pdst; + + if (src) { + BUG_ON(atomic_read(&src->refcount) == 0); + atomic_inc(&src->refcount); + put_io_context(dst); + *pdst = src; + } +} +EXPORT_SYMBOL(copy_io_context); + +void swap_io_context(struct io_context **ioc1, struct io_context **ioc2) +{ + struct io_context *temp; + temp = *ioc1; + *ioc1 = *ioc2; + *ioc2 = temp; +} +EXPORT_SYMBOL(swap_io_context); + +/* + * sysfs parts below + */ +struct queue_sysfs_entry { + struct attribute attr; + ssize_t (*show)(struct request_queue *, char *); + ssize_t (*store)(struct request_queue *, const char *, size_t); +}; + +static ssize_t +queue_var_show(unsigned int var, char *page) +{ + return sprintf(page, "%d\n", var); +} + +static ssize_t +queue_var_store(unsigned long *var, const char *page, size_t count) +{ + char *p = (char *) page; + + *var = simple_strtoul(p, &p, 10); + return count; +} + +static ssize_t queue_requests_show(struct request_queue *q, char *page) +{ + return queue_var_show(q->nr_requests, (page)); +} + +static ssize_t +queue_requests_store(struct request_queue *q, const char *page, size_t count) +{ + struct request_list *rl = &q->rq; + + int ret = queue_var_store(&q->nr_requests, page, count); + if (q->nr_requests < BLKDEV_MIN_RQ) + q->nr_requests = BLKDEV_MIN_RQ; + blk_queue_congestion_threshold(q); + + if (rl->count[READ] >= queue_congestion_on_threshold(q)) + set_queue_congested(q, READ); + else if (rl->count[READ] < queue_congestion_off_threshold(q)) + clear_queue_congested(q, READ); + + if (rl->count[WRITE] >= queue_congestion_on_threshold(q)) + set_queue_congested(q, WRITE); + else if (rl->count[WRITE] < queue_congestion_off_threshold(q)) + clear_queue_congested(q, WRITE); + + if (rl->count[READ] >= q->nr_requests) { + blk_set_queue_full(q, READ); + } else if (rl->count[READ]+1 <= q->nr_requests) { + blk_clear_queue_full(q, READ); + wake_up(&rl->wait[READ]); + } + + if (rl->count[WRITE] >= q->nr_requests) { + blk_set_queue_full(q, WRITE); + } else if (rl->count[WRITE]+1 <= q->nr_requests) { + blk_clear_queue_full(q, WRITE); + wake_up(&rl->wait[WRITE]); + } + return ret; +} + +static ssize_t queue_ra_show(struct request_queue *q, char *page) +{ + int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10); + + return queue_var_show(ra_kb, (page)); +} + +static ssize_t +queue_ra_store(struct request_queue *q, const char *page, size_t count) +{ + unsigned long ra_kb; + ssize_t ret = queue_var_store(&ra_kb, page, count); + + spin_lock_irq(q->queue_lock); + if (ra_kb > (q->max_sectors >> 1)) + ra_kb = (q->max_sectors >> 1); + + q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10); + spin_unlock_irq(q->queue_lock); + + return ret; +} + +static ssize_t queue_max_sectors_show(struct request_queue *q, char *page) +{ + int max_sectors_kb = q->max_sectors >> 1; + + return queue_var_show(max_sectors_kb, (page)); +} + +static ssize_t +queue_max_sectors_store(struct request_queue *q, const char *page, size_t count) +{ + unsigned long max_sectors_kb, + max_hw_sectors_kb = q->max_hw_sectors >> 1, + page_kb = 1 << (PAGE_CACHE_SHIFT - 10); + ssize_t ret = queue_var_store(&max_sectors_kb, page, count); + int ra_kb; + + if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb) + return -EINVAL; + /* + * Take the queue lock to update the readahead and max_sectors + * values synchronously: + */ + spin_lock_irq(q->queue_lock); + /* + * Trim readahead window as well, if necessary: + */ + ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10); + if (ra_kb > max_sectors_kb) + q->backing_dev_info.ra_pages = + max_sectors_kb >> (PAGE_CACHE_SHIFT - 10); + + q->max_sectors = max_sectors_kb << 1; + spin_unlock_irq(q->queue_lock); + + return ret; +} + +static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page) +{ + int max_hw_sectors_kb = q->max_hw_sectors >> 1; + + return queue_var_show(max_hw_sectors_kb, (page)); +} + + +static struct queue_sysfs_entry queue_requests_entry = { + .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR }, + .show = queue_requests_show, + .store = queue_requests_store, +}; + +static struct queue_sysfs_entry queue_ra_entry = { + .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR }, + .show = queue_ra_show, + .store = queue_ra_store, +}; + +static struct queue_sysfs_entry queue_max_sectors_entry = { + .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR }, + .show = queue_max_sectors_show, + .store = queue_max_sectors_store, +}; + +static struct queue_sysfs_entry queue_max_hw_sectors_entry = { + .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO }, + .show = queue_max_hw_sectors_show, +}; + +static struct queue_sysfs_entry queue_iosched_entry = { + .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR }, + .show = elv_iosched_show, + .store = elv_iosched_store, +}; + +static struct attribute *default_attrs[] = { + &queue_requests_entry.attr, + &queue_ra_entry.attr, + &queue_max_hw_sectors_entry.attr, + &queue_max_sectors_entry.attr, + &queue_iosched_entry.attr, + NULL, +}; + +#define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr) + +static ssize_t +queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page) +{ + struct queue_sysfs_entry *entry = to_queue(attr); + struct request_queue *q; + + q = container_of(kobj, struct request_queue, kobj); + if (!entry->show) + return -EIO; + + return entry->show(q, page); +} + +static ssize_t +queue_attr_store(struct kobject *kobj, struct attribute *attr, + const char *page, size_t length) +{ + struct queue_sysfs_entry *entry = to_queue(attr); + struct request_queue *q; + + q = container_of(kobj, struct request_queue, kobj); + if (!entry->store) + return -EIO; + + return entry->store(q, page, length); +} + +static struct sysfs_ops queue_sysfs_ops = { + .show = queue_attr_show, + .store = queue_attr_store, +}; + +static struct kobj_type queue_ktype = { + .sysfs_ops = &queue_sysfs_ops, + .default_attrs = default_attrs, +}; + +int blk_register_queue(struct gendisk *disk) +{ + int ret; + + request_queue_t *q = disk->queue; + + if (!q || !q->request_fn) + return -ENXIO; + + q->kobj.parent = kobject_get(&disk->kobj); + if (!q->kobj.parent) + return -EBUSY; + + snprintf(q->kobj.name, KOBJ_NAME_LEN, "%s", "queue"); + q->kobj.ktype = &queue_ktype; + + ret = kobject_register(&q->kobj); + if (ret < 0) + return ret; + + ret = elv_register_queue(q); + if (ret) { + kobject_unregister(&q->kobj); + return ret; + } + + return 0; +} + +void blk_unregister_queue(struct gendisk *disk) +{ + request_queue_t *q = disk->queue; + + if (q && q->request_fn) { + elv_unregister_queue(q); + + kobject_unregister(&q->kobj); + kobject_put(&disk->kobj); + } +} diff --git a/block/noop-iosched.c b/block/noop-iosched.c new file mode 100644 index 00000000000..e54f006e7e6 --- /dev/null +++ b/block/noop-iosched.c @@ -0,0 +1,46 @@ +/* + * elevator noop + */ +#include <linux/blkdev.h> +#include <linux/elevator.h> +#include <linux/bio.h> +#include <linux/module.h> +#include <linux/init.h> + +static void elevator_noop_add_request(request_queue_t *q, struct request *rq) +{ + rq->flags |= REQ_NOMERGE; + elv_dispatch_add_tail(q, rq); +} + +static int elevator_noop_dispatch(request_queue_t *q, int force) +{ + return 0; +} + +static struct elevator_type elevator_noop = { + .ops = { + .elevator_dispatch_fn = elevator_noop_dispatch, + .elevator_add_req_fn = elevator_noop_add_request, + }, + .elevator_name = "noop", + .elevator_owner = THIS_MODULE, +}; + +static int __init noop_init(void) +{ + return elv_register(&elevator_noop); +} + +static void __exit noop_exit(void) +{ + elv_unregister(&elevator_noop); +} + +module_init(noop_init); +module_exit(noop_exit); + + +MODULE_AUTHOR("Jens Axboe"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("No-op IO scheduler"); diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c new file mode 100644 index 00000000000..382dea7b224 --- /dev/null +++ b/block/scsi_ioctl.c @@ -0,0 +1,589 @@ +/* + * Copyright (C) 2001 Jens Axboe <axboe@suse.de> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public Licens + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111- + * + */ +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/string.h> +#include <linux/module.h> +#include <linux/blkdev.h> +#include <linux/completion.h> +#include <linux/cdrom.h> +#include <linux/slab.h> +#include <linux/times.h> +#include <asm/uaccess.h> + +#include <scsi/scsi.h> +#include <scsi/scsi_ioctl.h> +#include <scsi/scsi_cmnd.h> + +/* Command group 3 is reserved and should never be used. */ +const unsigned char scsi_command_size[8] = +{ + 6, 10, 10, 12, + 16, 12, 10, 10 +}; + +EXPORT_SYMBOL(scsi_command_size); + +#define BLK_DEFAULT_TIMEOUT (60 * HZ) + +#include <scsi/sg.h> + +static int sg_get_version(int __user *p) +{ + static int sg_version_num = 30527; + return put_user(sg_version_num, p); +} + +static int scsi_get_idlun(request_queue_t *q, int __user *p) +{ + return put_user(0, p); +} + +static int scsi_get_bus(request_queue_t *q, int __user *p) +{ + return put_user(0, p); +} + +static int sg_get_timeout(request_queue_t *q) +{ + return q->sg_timeout / (HZ / USER_HZ); +} + +static int sg_set_timeout(request_queue_t *q, int __user *p) +{ + int timeout, err = get_user(timeout, p); + + if (!err) + q->sg_timeout = timeout * (HZ / USER_HZ); + + return err; +} + +static int sg_get_reserved_size(request_queue_t *q, int __user *p) +{ + return put_user(q->sg_reserved_size, p); +} + +static int sg_set_reserved_size(request_queue_t *q, int __user *p) +{ + int size, err = get_user(size, p); + + if (err) + return err; + + if (size < 0) + return -EINVAL; + if (size > (q->max_sectors << 9)) + size = q->max_sectors << 9; + + q->sg_reserved_size = size; + return 0; +} + +/* + * will always return that we are ATAPI even for a real SCSI drive, I'm not + * so sure this is worth doing anything about (why would you care??) + */ +static int sg_emulated_host(request_queue_t *q, int __user *p) +{ + return put_user(1, p); +} + +#define CMD_READ_SAFE 0x01 +#define CMD_WRITE_SAFE 0x02 +#define CMD_WARNED 0x04 +#define safe_for_read(cmd) [cmd] = CMD_READ_SAFE +#define safe_for_write(cmd) [cmd] = CMD_WRITE_SAFE + +static int verify_command(struct file *file, unsigned char *cmd) +{ + static unsigned char cmd_type[256] = { + + /* Basic read-only commands */ + safe_for_read(TEST_UNIT_READY), + safe_for_read(REQUEST_SENSE), + safe_for_read(READ_6), + safe_for_read(READ_10), + safe_for_read(READ_12), + safe_for_read(READ_16), + safe_for_read(READ_BUFFER), + safe_for_read(READ_DEFECT_DATA), + safe_for_read(READ_LONG), + safe_for_read(INQUIRY), + safe_for_read(MODE_SENSE), + safe_for_read(MODE_SENSE_10), + safe_for_read(LOG_SENSE), + safe_for_read(START_STOP), + safe_for_read(GPCMD_VERIFY_10), + safe_for_read(VERIFY_16), + + /* Audio CD commands */ + safe_for_read(GPCMD_PLAY_CD), + safe_for_read(GPCMD_PLAY_AUDIO_10), + safe_for_read(GPCMD_PLAY_AUDIO_MSF), + safe_for_read(GPCMD_PLAY_AUDIO_TI), + safe_for_read(GPCMD_PAUSE_RESUME), + + /* CD/DVD data reading */ + safe_for_read(GPCMD_READ_BUFFER_CAPACITY), + safe_for_read(GPCMD_READ_CD), + safe_for_read(GPCMD_READ_CD_MSF), + safe_for_read(GPCMD_READ_DISC_INFO), + safe_for_read(GPCMD_READ_CDVD_CAPACITY), + safe_for_read(GPCMD_READ_DVD_STRUCTURE), + safe_for_read(GPCMD_READ_HEADER), + safe_for_read(GPCMD_READ_TRACK_RZONE_INFO), + safe_for_read(GPCMD_READ_SUBCHANNEL), + safe_for_read(GPCMD_READ_TOC_PMA_ATIP), + safe_for_read(GPCMD_REPORT_KEY), + safe_for_read(GPCMD_SCAN), + safe_for_read(GPCMD_GET_CONFIGURATION), + safe_for_read(GPCMD_READ_FORMAT_CAPACITIES), + safe_for_read(GPCMD_GET_EVENT_STATUS_NOTIFICATION), + safe_for_read(GPCMD_GET_PERFORMANCE), + safe_for_read(GPCMD_SEEK), + safe_for_read(GPCMD_STOP_PLAY_SCAN), + + /* Basic writing commands */ + safe_for_write(WRITE_6), + safe_for_write(WRITE_10), + safe_for_write(WRITE_VERIFY), + safe_for_write(WRITE_12), + safe_for_write(WRITE_VERIFY_12), + safe_for_write(WRITE_16), + safe_for_write(WRITE_LONG), + safe_for_write(WRITE_LONG_2), + safe_for_write(ERASE), + safe_for_write(GPCMD_MODE_SELECT_10), + safe_for_write(MODE_SELECT), + safe_for_write(LOG_SELECT), + safe_for_write(GPCMD_BLANK), + safe_for_write(GPCMD_CLOSE_TRACK), + safe_for_write(GPCMD_FLUSH_CACHE), + safe_for_write(GPCMD_FORMAT_UNIT), + safe_for_write(GPCMD_REPAIR_RZONE_TRACK), + safe_for_write(GPCMD_RESERVE_RZONE_TRACK), + safe_for_write(GPCMD_SEND_DVD_STRUCTURE), + safe_for_write(GPCMD_SEND_EVENT), + safe_for_write(GPCMD_SEND_KEY), + safe_for_write(GPCMD_SEND_OPC), + safe_for_write(GPCMD_SEND_CUE_SHEET), + safe_for_write(GPCMD_SET_SPEED), + safe_for_write(GPCMD_PREVENT_ALLOW_MEDIUM_REMOVAL), + safe_for_write(GPCMD_LOAD_UNLOAD), + safe_for_write(GPCMD_SET_STREAMING), + }; + unsigned char type = cmd_type[cmd[0]]; + + /* Anybody who can open the device can do a read-safe command */ + if (type & CMD_READ_SAFE) + return 0; + + /* Write-safe commands just require a writable open.. */ + if (type & CMD_WRITE_SAFE) { + if (file->f_mode & FMODE_WRITE) + return 0; + } + + /* And root can do any command.. */ + if (capable(CAP_SYS_RAWIO)) + return 0; + + if (!type) { + cmd_type[cmd[0]] = CMD_WARNED; + printk(KERN_WARNING "scsi: unknown opcode 0x%02x\n", cmd[0]); + } + + /* Otherwise fail it with an "Operation not permitted" */ + return -EPERM; +} + +static int sg_io(struct file *file, request_queue_t *q, + struct gendisk *bd_disk, struct sg_io_hdr *hdr) +{ + unsigned long start_time; + int writing = 0, ret = 0; + struct request *rq; + struct bio *bio; + char sense[SCSI_SENSE_BUFFERSIZE]; + unsigned char cmd[BLK_MAX_CDB]; + + if (hdr->interface_id != 'S') + return -EINVAL; + if (hdr->cmd_len > BLK_MAX_CDB) + return -EINVAL; + if (copy_from_user(cmd, hdr->cmdp, hdr->cmd_len)) + return -EFAULT; + if (verify_command(file, cmd)) + return -EPERM; + + if (hdr->dxfer_len > (q->max_sectors << 9)) + return -EIO; + + if (hdr->dxfer_len) + switch (hdr->dxfer_direction) { + default: + return -EINVAL; + case SG_DXFER_TO_FROM_DEV: + case SG_DXFER_TO_DEV: + writing = 1; + break; + case SG_DXFER_FROM_DEV: + break; + } + + rq = blk_get_request(q, writing ? WRITE : READ, GFP_KERNEL); + if (!rq) + return -ENOMEM; + + if (hdr->iovec_count) { + const int size = sizeof(struct sg_iovec) * hdr->iovec_count; + struct sg_iovec *iov; + + iov = kmalloc(size, GFP_KERNEL); + if (!iov) { + ret = -ENOMEM; + goto out; + } + + if (copy_from_user(iov, hdr->dxferp, size)) { + kfree(iov); + ret = -EFAULT; + goto out; + } + + ret = blk_rq_map_user_iov(q, rq, iov, hdr->iovec_count); + kfree(iov); + } else if (hdr->dxfer_len) + ret = blk_rq_map_user(q, rq, hdr->dxferp, hdr->dxfer_len); + + if (ret) + goto out; + + /* + * fill in request structure + */ + rq->cmd_len = hdr->cmd_len; + memcpy(rq->cmd, cmd, hdr->cmd_len); + if (sizeof(rq->cmd) != hdr->cmd_len) + memset(rq->cmd + hdr->cmd_len, 0, sizeof(rq->cmd) - hdr->cmd_len); + + memset(sense, 0, sizeof(sense)); + rq->sense = sense; + rq->sense_len = 0; + + rq->flags |= REQ_BLOCK_PC; + bio = rq->bio; + + /* + * bounce this after holding a reference to the original bio, it's + * needed for proper unmapping + */ + if (rq->bio) + blk_queue_bounce(q, &rq->bio); + + rq->timeout = (hdr->timeout * HZ) / 1000; + if (!rq->timeout) + rq->timeout = q->sg_timeout; + if (!rq->timeout) + rq->timeout = BLK_DEFAULT_TIMEOUT; + + start_time = jiffies; + + /* ignore return value. All information is passed back to caller + * (if he doesn't check that is his problem). + * N.B. a non-zero SCSI status is _not_ necessarily an error. + */ + blk_execute_rq(q, bd_disk, rq, 0); + + /* write to all output members */ + hdr->status = 0xff & rq->errors; + hdr->masked_status = status_byte(rq->errors); + hdr->msg_status = msg_byte(rq->errors); + hdr->host_status = host_byte(rq->errors); + hdr->driver_status = driver_byte(rq->errors); + hdr->info = 0; + if (hdr->masked_status || hdr->host_status || hdr->driver_status) + hdr->info |= SG_INFO_CHECK; + hdr->resid = rq->data_len; + hdr->duration = ((jiffies - start_time) * 1000) / HZ; + hdr->sb_len_wr = 0; + + if (rq->sense_len && hdr->sbp) { + int len = min((unsigned int) hdr->mx_sb_len, rq->sense_len); + + if (!copy_to_user(hdr->sbp, rq->sense, len)) + hdr->sb_len_wr = len; + } + + if (blk_rq_unmap_user(bio, hdr->dxfer_len)) + ret = -EFAULT; + + /* may not have succeeded, but output values written to control + * structure (struct sg_io_hdr). */ +out: + blk_put_request(rq); + return ret; +} + +#define OMAX_SB_LEN 16 /* For backward compatibility */ + +static int sg_scsi_ioctl(struct file *file, request_queue_t *q, + struct gendisk *bd_disk, Scsi_Ioctl_Command __user *sic) +{ + struct request *rq; + int err; + unsigned int in_len, out_len, bytes, opcode, cmdlen; + char *buffer = NULL, sense[SCSI_SENSE_BUFFERSIZE]; + + /* + * get in an out lengths, verify they don't exceed a page worth of data + */ + if (get_user(in_len, &sic->inlen)) + return -EFAULT; + if (get_user(out_len, &sic->outlen)) + return -EFAULT; + if (in_len > PAGE_SIZE || out_len > PAGE_SIZE) + return -EINVAL; + if (get_user(opcode, sic->data)) + return -EFAULT; + + bytes = max(in_len, out_len); + if (bytes) { + buffer = kmalloc(bytes, q->bounce_gfp | GFP_USER| __GFP_NOWARN); + if (!buffer) + return -ENOMEM; + + memset(buffer, 0, bytes); + } + + rq = blk_get_request(q, in_len ? WRITE : READ, __GFP_WAIT); + + cmdlen = COMMAND_SIZE(opcode); + + /* + * get command and data to send to device, if any + */ + err = -EFAULT; + rq->cmd_len = cmdlen; + if (copy_from_user(rq->cmd, sic->data, cmdlen)) + goto error; + + if (copy_from_user(buffer, sic->data + cmdlen, in_len)) + goto error; + + err = verify_command(file, rq->cmd); + if (err) + goto error; + + switch (opcode) { + case SEND_DIAGNOSTIC: + case FORMAT_UNIT: + rq->timeout = FORMAT_UNIT_TIMEOUT; + break; + case START_STOP: + rq->timeout = START_STOP_TIMEOUT; + break; + case MOVE_MEDIUM: + rq->timeout = MOVE_MEDIUM_TIMEOUT; + break; + case READ_ELEMENT_STATUS: + rq->timeout = READ_ELEMENT_STATUS_TIMEOUT; + break; + case READ_DEFECT_DATA: + rq->timeout = READ_DEFECT_DATA_TIMEOUT; + break; + default: + rq->timeout = BLK_DEFAULT_TIMEOUT; + break; + } + + memset(sense, 0, sizeof(sense)); + rq->sense = sense; + rq->sense_len = 0; + + rq->data = buffer; + rq->data_len = bytes; + rq->flags |= REQ_BLOCK_PC; + + blk_execute_rq(q, bd_disk, rq, 0); + err = rq->errors & 0xff; /* only 8 bit SCSI status */ + if (err) { + if (rq->sense_len && rq->sense) { + bytes = (OMAX_SB_LEN > rq->sense_len) ? + rq->sense_len : OMAX_SB_LEN; + if (copy_to_user(sic->data, rq->sense, bytes)) + err = -EFAULT; + } + } else { + if (copy_to_user(sic->data, buffer, out_len)) + err = -EFAULT; + } + +error: + kfree(buffer); + blk_put_request(rq); + return err; +} + +int scsi_cmd_ioctl(struct file *file, struct gendisk *bd_disk, unsigned int cmd, void __user *arg) +{ + request_queue_t *q; + struct request *rq; + int close = 0, err; + + q = bd_disk->queue; + if (!q) + return -ENXIO; + + if (blk_get_queue(q)) + return -ENXIO; + + switch (cmd) { + /* + * new sgv3 interface + */ + case SG_GET_VERSION_NUM: + err = sg_get_version(arg); + break; + case SCSI_IOCTL_GET_IDLUN: + err = scsi_get_idlun(q, arg); + break; + case SCSI_IOCTL_GET_BUS_NUMBER: + err = scsi_get_bus(q, arg); + break; + case SG_SET_TIMEOUT: + err = sg_set_timeout(q, arg); + break; + case SG_GET_TIMEOUT: + err = sg_get_timeout(q); + break; + case SG_GET_RESERVED_SIZE: + err = sg_get_reserved_size(q, arg); + break; + case SG_SET_RESERVED_SIZE: + err = sg_set_reserved_size(q, arg); + break; + case SG_EMULATED_HOST: + err = sg_emulated_host(q, arg); + break; + case SG_IO: { + struct sg_io_hdr hdr; + + err = -EFAULT; + if (copy_from_user(&hdr, arg, sizeof(hdr))) + break; + err = sg_io(file, q, bd_disk, &hdr); + if (err == -EFAULT) + break; + + if (copy_to_user(arg, &hdr, sizeof(hdr))) + err = -EFAULT; + break; + } + case CDROM_SEND_PACKET: { + struct cdrom_generic_command cgc; + struct sg_io_hdr hdr; + + err = -EFAULT; + if (copy_from_user(&cgc, arg, sizeof(cgc))) + break; + cgc.timeout = clock_t_to_jiffies(cgc.timeout); + memset(&hdr, 0, sizeof(hdr)); + hdr.interface_id = 'S'; + hdr.cmd_len = sizeof(cgc.cmd); + hdr.dxfer_len = cgc.buflen; + err = 0; + switch (cgc.data_direction) { + case CGC_DATA_UNKNOWN: + hdr.dxfer_direction = SG_DXFER_UNKNOWN; + break; + case CGC_DATA_WRITE: + hdr.dxfer_direction = SG_DXFER_TO_DEV; + break; + case CGC_DATA_READ: + hdr.dxfer_direction = SG_DXFER_FROM_DEV; + break; + case CGC_DATA_NONE: + hdr.dxfer_direction = SG_DXFER_NONE; + break; + default: + err = -EINVAL; + } + if (err) + break; + + hdr.dxferp = cgc.buffer; + hdr.sbp = cgc.sense; + if (hdr.sbp) + hdr.mx_sb_len = sizeof(struct request_sense); + hdr.timeout = cgc.timeout; + hdr.cmdp = ((struct cdrom_generic_command __user*) arg)->cmd; + hdr.cmd_len = sizeof(cgc.cmd); + + err = sg_io(file, q, bd_disk, &hdr); + if (err == -EFAULT) + break; + + if (hdr.status) + err = -EIO; + + cgc.stat = err; + cgc.buflen = hdr.resid; + if (copy_to_user(arg, &cgc, sizeof(cgc))) + err = -EFAULT; + + break; + } + + /* + * old junk scsi send command ioctl + */ + case SCSI_IOCTL_SEND_COMMAND: + printk(KERN_WARNING "program %s is using a deprecated SCSI ioctl, please convert it to SG_IO\n", current->comm); + err = -EINVAL; + if (!arg) + break; + + err = sg_scsi_ioctl(file, q, bd_disk, arg); + break; + case CDROMCLOSETRAY: + close = 1; + case CDROMEJECT: + rq = blk_get_request(q, WRITE, __GFP_WAIT); + rq->flags |= REQ_BLOCK_PC; + rq->data = NULL; + rq->data_len = 0; + rq->timeout = BLK_DEFAULT_TIMEOUT; + memset(rq->cmd, 0, sizeof(rq->cmd)); + rq->cmd[0] = GPCMD_START_STOP_UNIT; + rq->cmd[4] = 0x02 + (close != 0); + rq->cmd_len = 6; + err = blk_execute_rq(q, bd_disk, rq, 0); + blk_put_request(rq); + break; + default: + err = -ENOTTY; + } + + blk_put_queue(q); + return err; +} + +EXPORT_SYMBOL(scsi_cmd_ioctl); |