diff options
Diffstat (limited to 'drivers/block/elevator.c')
| -rw-r--r-- | drivers/block/elevator.c | 712 |
1 files changed, 0 insertions, 712 deletions
diff --git a/drivers/block/elevator.c b/drivers/block/elevator.c deleted file mode 100644 index 98f0126a2de..00000000000 --- a/drivers/block/elevator.c +++ /dev/null @@ -1,712 +0,0 @@ -/* - * 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 <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); - -inline int elv_try_last_merge(request_queue_t *q, struct bio *bio) -{ - if (q->last_merge) - return elv_try_merge(q->last_merge, bio); - - return ELEVATOR_NO_MERGE; -} -EXPORT_SYMBOL(elv_try_last_merge); - -static struct elevator_type *elevator_find(const char *name) -{ - struct elevator_type *e = NULL; - struct list_head *entry; - - spin_lock_irq(&elv_list_lock); - 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; - } - } - spin_unlock_irq(&elv_list_lock); - - 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 = elevator_find(name); - - if (!e) - return NULL; - if (!try_module_get(e->elevator_owner)) - return NULL; - - 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; - - INIT_LIST_HEAD(&q->queue_head); - q->last_merge = NULL; - 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) -{ - /* - * check if default is set and exists - */ - if (chosen_elevator[0] && elevator_find(chosen_elevator)) - return; - -#if defined(CONFIG_IOSCHED_AS) - strcpy(chosen_elevator, "anticipatory"); -#elif defined(CONFIG_IOSCHED_DEADLINE) - strcpy(chosen_elevator, "deadline"); -#elif defined(CONFIG_IOSCHED_CFQ) - strcpy(chosen_elevator, "cfq"); -#elif defined(CONFIG_IOSCHED_NOOP) - strcpy(chosen_elevator, "noop"); -#else -#error "You must build at least 1 IO scheduler into the kernel" -#endif -} - -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; - - 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); -} - -int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) -{ - elevator_t *e = q->elevator; - - 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); -} - -void elv_merge_requests(request_queue_t *q, struct request *rq, - struct request *next) -{ - elevator_t *e = q->elevator; - - if (q->last_merge == next) - q->last_merge = NULL; - - if (e->ops->elevator_merge_req_fn) - e->ops->elevator_merge_req_fn(q, rq, next); -} - -/* - * For careful internal use by the block layer. Essentially the same as - * a requeue in that it tells the io scheduler that this request is not - * active in the driver or hardware anymore, but we don't want the request - * added back to the scheduler. Function is not exported. - */ -void elv_deactivate_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--; - - rq->flags &= ~REQ_STARTED; - - if (e->ops->elevator_deactivate_req_fn) - e->ops->elevator_deactivate_req_fn(q, rq); -} - -void elv_requeue_request(request_queue_t *q, struct request *rq) -{ - elv_deactivate_request(q, rq); - - /* - * 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; - } - - /* - * the request is prepped and may have some resources allocated. - * allowing unprepped requests to pass this one may cause resource - * deadlock. turn on softbarrier. - */ - rq->flags |= REQ_SOFTBARRIER; - - /* - * if iosched has an explicit requeue hook, then use that. otherwise - * just put the request at the front of the queue - */ - if (q->elevator->ops->elevator_requeue_req_fn) - q->elevator->ops->elevator_requeue_req_fn(q, rq); - else - __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0); -} - -void __elv_add_request(request_queue_t *q, struct request *rq, int where, - int plug) -{ - /* - * barriers implicitly indicate back insertion - */ - if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER) && - where == ELEVATOR_INSERT_SORT) - where = ELEVATOR_INSERT_BACK; - - if (plug) - blk_plug_device(q); - - rq->q = q; - - if (!test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)) { - q->elevator->ops->elevator_add_req_fn(q, rq, where); - - 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); - } - } else - /* - * if drain is set, store the request "locally". when the drain - * is finished, the requests will be handed ordered to the io - * scheduler - */ - list_add_tail(&rq->queuelist, &q->drain_list); -} - -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 = q->elevator->ops->elevator_next_req_fn(q); - - /* - * if this is a barrier write and the device has to issue a - * flush sequence to support it, check how far we are - */ - if (rq && 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) { - /* - * 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 (rq == q->last_merge) - q->last_merge = 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. turn on softbarrier. - */ - rq->flags |= REQ_SOFTBARRIER; - 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_remove_request(request_queue_t *q, struct request *rq) -{ - elevator_t *e = q->elevator; - - /* - * 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. note that we only account requests that the - * driver has seen (REQ_STARTED set), to avoid false accounting - * for request-request merges - */ - if (blk_account_rq(rq)) - q->in_flight++; - - /* - * the main clearing point for q->last_merge is on retrieval of - * request by driver (it calls elv_next_request()), but it _can_ - * also happen here if a request is added to the queue but later - * deleted without ever being given to driver (merged with another - * request). - */ - if (rq == q->last_merge) - q->last_merge = NULL; - - if (e->ops->elevator_remove_req_fn) - e->ops->elevator_remove_req_fn(q, rq); -} - -int elv_queue_empty(request_queue_t *q) -{ - elevator_t *e = q->elevator; - - if (e->ops->elevator_queue_empty_fn) - return e->ops->elevator_queue_empty_fn(q); - - return list_empty(&q->queue_head); -} - -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, - int 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 (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) -{ - if (elevator_find(e->elevator_name)) - BUG(); - - spin_lock_irq(&elv_list_lock); - 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) -{ - 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. we also do an intermediate - * switch to noop to ensure safety with stack-allocated requests, since they - * don't originate from the block layer allocator. noop is safe here, because - * it never needs to touch the elevator itself for completion events. DRAIN - * flags will make sure we don't touch it for additions either. - */ -static void elevator_switch(request_queue_t *q, struct elevator_type *new_e) -{ - elevator_t *e = kmalloc(sizeof(elevator_t), GFP_KERNEL); - struct elevator_type *noop_elevator = NULL; - elevator_t *old_elevator; - - if (!e) - goto error; - - /* - * first step, drain requests from the block freelist - */ - blk_wait_queue_drained(q, 0); - - /* - * unregister old elevator data - */ - elv_unregister_queue(q); - old_elevator = q->elevator; - - /* - * next step, switch to noop since it uses no private rq structures - * and doesn't allocate any memory for anything. then wait for any - * non-fs requests in-flight - */ - noop_elevator = elevator_get("noop"); - spin_lock_irq(q->queue_lock); - elevator_attach(q, noop_elevator, e); - spin_unlock_irq(q->queue_lock); - - blk_wait_queue_drained(q, 1); - - /* - * 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 start queue again - */ - elevator_exit(old_elevator); - blk_finish_queue_drain(q); - elevator_put(noop_elevator); - 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); -fail: - q->elevator = old_elevator; - elv_register_queue(q); - blk_finish_queue_drain(q); -error: - if (noop_elevator) - elevator_put(noop_elevator); - 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)) - 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_add_request); -EXPORT_SYMBOL(__elv_add_request); -EXPORT_SYMBOL(elv_requeue_request); -EXPORT_SYMBOL(elv_next_request); -EXPORT_SYMBOL(elv_remove_request); -EXPORT_SYMBOL(elv_queue_empty); -EXPORT_SYMBOL(elv_completed_request); -EXPORT_SYMBOL(elevator_exit); -EXPORT_SYMBOL(elevator_init); |