diff options
Diffstat (limited to 'drivers/block/ll_rw_blk.c')
| -rw-r--r-- | drivers/block/ll_rw_blk.c | 3613 |
1 files changed, 0 insertions, 3613 deletions
diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c deleted file mode 100644 index 2747741677f..00000000000 --- a/drivers/block/ll_rw_blk.c +++ /dev/null @@ -1,3613 +0,0 @@ -/* - * 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); - } -} |