2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 1994, Karl Keyte: Added support for disk statistics
4 * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
5 * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de>
6 * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au>
8 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
12 * This handles all read/write requests to block devices
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/backing-dev.h>
17 #include <linux/bio.h>
18 #include <linux/blkdev.h>
19 #include <linux/highmem.h>
21 #include <linux/kernel_stat.h>
22 #include <linux/string.h>
23 #include <linux/init.h>
24 #include <linux/completion.h>
25 #include <linux/slab.h>
26 #include <linux/swap.h>
27 #include <linux/writeback.h>
28 #include <linux/task_io_accounting_ops.h>
29 #include <linux/fault-inject.h>
31 #define CREATE_TRACE_POINTS
32 #include <trace/events/block.h>
36 EXPORT_TRACEPOINT_SYMBOL_GPL(block_remap);
37 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
38 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
40 static int __make_request(struct request_queue *q, struct bio *bio);
43 * For the allocated request tables
45 static struct kmem_cache *request_cachep;
48 * For queue allocation
50 struct kmem_cache *blk_requestq_cachep;
53 * Controlling structure to kblockd
55 static struct workqueue_struct *kblockd_workqueue;
57 static void drive_stat_acct(struct request *rq, int new_io)
59 struct hd_struct *part;
60 int rw = rq_data_dir(rq);
63 if (!blk_do_io_stat(rq))
66 cpu = part_stat_lock();
67 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
70 part_stat_inc(cpu, part, merges[rw]);
72 part_round_stats(cpu, part);
73 part_inc_in_flight(part, rw);
79 void blk_queue_congestion_threshold(struct request_queue *q)
83 nr = q->nr_requests - (q->nr_requests / 8) + 1;
84 if (nr > q->nr_requests)
86 q->nr_congestion_on = nr;
88 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
91 q->nr_congestion_off = nr;
95 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
98 * Locates the passed device's request queue and returns the address of its
101 * Will return NULL if the request queue cannot be located.
103 struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
105 struct backing_dev_info *ret = NULL;
106 struct request_queue *q = bdev_get_queue(bdev);
109 ret = &q->backing_dev_info;
112 EXPORT_SYMBOL(blk_get_backing_dev_info);
114 void blk_rq_init(struct request_queue *q, struct request *rq)
116 memset(rq, 0, sizeof(*rq));
118 INIT_LIST_HEAD(&rq->queuelist);
119 INIT_LIST_HEAD(&rq->timeout_list);
122 rq->__sector = (sector_t) -1;
123 INIT_HLIST_NODE(&rq->hash);
124 RB_CLEAR_NODE(&rq->rb_node);
126 rq->cmd_len = BLK_MAX_CDB;
129 rq->start_time = jiffies;
130 set_start_time_ns(rq);
132 EXPORT_SYMBOL(blk_rq_init);
134 static void req_bio_endio(struct request *rq, struct bio *bio,
135 unsigned int nbytes, int error)
137 struct request_queue *q = rq->q;
139 if (&q->bar_rq != rq) {
141 clear_bit(BIO_UPTODATE, &bio->bi_flags);
142 else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
145 if (unlikely(nbytes > bio->bi_size)) {
146 printk(KERN_ERR "%s: want %u bytes done, %u left\n",
147 __func__, nbytes, bio->bi_size);
148 nbytes = bio->bi_size;
151 if (unlikely(rq->cmd_flags & REQ_QUIET))
152 set_bit(BIO_QUIET, &bio->bi_flags);
154 bio->bi_size -= nbytes;
155 bio->bi_sector += (nbytes >> 9);
157 if (bio_integrity(bio))
158 bio_integrity_advance(bio, nbytes);
160 if (bio->bi_size == 0)
161 bio_endio(bio, error);
165 * Okay, this is the barrier request in progress, just
168 if (error && !q->orderr)
173 void blk_dump_rq_flags(struct request *rq, char *msg)
177 printk(KERN_INFO "%s: dev %s: type=%x, flags=%x\n", msg,
178 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
181 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n",
182 (unsigned long long)blk_rq_pos(rq),
183 blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
184 printk(KERN_INFO " bio %p, biotail %p, buffer %p, len %u\n",
185 rq->bio, rq->biotail, rq->buffer, blk_rq_bytes(rq));
187 if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
188 printk(KERN_INFO " cdb: ");
189 for (bit = 0; bit < BLK_MAX_CDB; bit++)
190 printk("%02x ", rq->cmd[bit]);
194 EXPORT_SYMBOL(blk_dump_rq_flags);
197 * "plug" the device if there are no outstanding requests: this will
198 * force the transfer to start only after we have put all the requests
201 * This is called with interrupts off and no requests on the queue and
202 * with the queue lock held.
204 void blk_plug_device(struct request_queue *q)
206 WARN_ON(!irqs_disabled());
209 * don't plug a stopped queue, it must be paired with blk_start_queue()
210 * which will restart the queueing
212 if (blk_queue_stopped(q))
215 if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) {
216 mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
220 EXPORT_SYMBOL(blk_plug_device);
223 * blk_plug_device_unlocked - plug a device without queue lock held
224 * @q: The &struct request_queue to plug
227 * Like @blk_plug_device(), but grabs the queue lock and disables
230 void blk_plug_device_unlocked(struct request_queue *q)
234 spin_lock_irqsave(q->queue_lock, flags);
236 spin_unlock_irqrestore(q->queue_lock, flags);
238 EXPORT_SYMBOL(blk_plug_device_unlocked);
241 * remove the queue from the plugged list, if present. called with
242 * queue lock held and interrupts disabled.
244 int blk_remove_plug(struct request_queue *q)
246 WARN_ON(!irqs_disabled());
248 if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q))
251 del_timer(&q->unplug_timer);
254 EXPORT_SYMBOL(blk_remove_plug);
257 * remove the plug and let it rip..
259 void __generic_unplug_device(struct request_queue *q)
261 if (unlikely(blk_queue_stopped(q)))
263 if (!blk_remove_plug(q) && !blk_queue_nonrot(q))
270 * generic_unplug_device - fire a request queue
271 * @q: The &struct request_queue in question
274 * Linux uses plugging to build bigger requests queues before letting
275 * the device have at them. If a queue is plugged, the I/O scheduler
276 * is still adding and merging requests on the queue. Once the queue
277 * gets unplugged, the request_fn defined for the queue is invoked and
280 void generic_unplug_device(struct request_queue *q)
282 if (blk_queue_plugged(q)) {
283 spin_lock_irq(q->queue_lock);
284 __generic_unplug_device(q);
285 spin_unlock_irq(q->queue_lock);
288 EXPORT_SYMBOL(generic_unplug_device);
290 static void blk_backing_dev_unplug(struct backing_dev_info *bdi,
293 struct request_queue *q = bdi->unplug_io_data;
298 void blk_unplug_work(struct work_struct *work)
300 struct request_queue *q =
301 container_of(work, struct request_queue, unplug_work);
303 trace_block_unplug_io(q);
307 void blk_unplug_timeout(unsigned long data)
309 struct request_queue *q = (struct request_queue *)data;
311 trace_block_unplug_timer(q);
312 kblockd_schedule_work(q, &q->unplug_work);
315 void blk_unplug(struct request_queue *q)
318 * devices don't necessarily have an ->unplug_fn defined
321 trace_block_unplug_io(q);
325 EXPORT_SYMBOL(blk_unplug);
328 * blk_start_queue - restart a previously stopped queue
329 * @q: The &struct request_queue in question
332 * blk_start_queue() will clear the stop flag on the queue, and call
333 * the request_fn for the queue if it was in a stopped state when
334 * entered. Also see blk_stop_queue(). Queue lock must be held.
336 void blk_start_queue(struct request_queue *q)
338 WARN_ON(!irqs_disabled());
340 queue_flag_clear(QUEUE_FLAG_STOPPED, q);
343 EXPORT_SYMBOL(blk_start_queue);
346 * blk_stop_queue - stop a queue
347 * @q: The &struct request_queue in question
350 * The Linux block layer assumes that a block driver will consume all
351 * entries on the request queue when the request_fn strategy is called.
352 * Often this will not happen, because of hardware limitations (queue
353 * depth settings). If a device driver gets a 'queue full' response,
354 * or if it simply chooses not to queue more I/O at one point, it can
355 * call this function to prevent the request_fn from being called until
356 * the driver has signalled it's ready to go again. This happens by calling
357 * blk_start_queue() to restart queue operations. Queue lock must be held.
359 void blk_stop_queue(struct request_queue *q)
362 queue_flag_set(QUEUE_FLAG_STOPPED, q);
364 EXPORT_SYMBOL(blk_stop_queue);
367 * blk_sync_queue - cancel any pending callbacks on a queue
371 * The block layer may perform asynchronous callback activity
372 * on a queue, such as calling the unplug function after a timeout.
373 * A block device may call blk_sync_queue to ensure that any
374 * such activity is cancelled, thus allowing it to release resources
375 * that the callbacks might use. The caller must already have made sure
376 * that its ->make_request_fn will not re-add plugging prior to calling
380 void blk_sync_queue(struct request_queue *q)
382 del_timer_sync(&q->unplug_timer);
383 del_timer_sync(&q->timeout);
384 cancel_work_sync(&q->unplug_work);
386 EXPORT_SYMBOL(blk_sync_queue);
389 * __blk_run_queue - run a single device queue
390 * @q: The queue to run
393 * See @blk_run_queue. This variant must be called with the queue lock
394 * held and interrupts disabled.
397 void __blk_run_queue(struct request_queue *q)
401 if (unlikely(blk_queue_stopped(q)))
404 if (elv_queue_empty(q))
408 * Only recurse once to avoid overrunning the stack, let the unplug
409 * handling reinvoke the handler shortly if we already got there.
411 if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
413 queue_flag_clear(QUEUE_FLAG_REENTER, q);
415 queue_flag_set(QUEUE_FLAG_PLUGGED, q);
416 kblockd_schedule_work(q, &q->unplug_work);
419 EXPORT_SYMBOL(__blk_run_queue);
422 * blk_run_queue - run a single device queue
423 * @q: The queue to run
426 * Invoke request handling on this queue, if it has pending work to do.
427 * May be used to restart queueing when a request has completed.
429 void blk_run_queue(struct request_queue *q)
433 spin_lock_irqsave(q->queue_lock, flags);
435 spin_unlock_irqrestore(q->queue_lock, flags);
437 EXPORT_SYMBOL(blk_run_queue);
439 void blk_put_queue(struct request_queue *q)
441 kobject_put(&q->kobj);
444 void blk_cleanup_queue(struct request_queue *q)
447 * We know we have process context here, so we can be a little
448 * cautious and ensure that pending block actions on this device
449 * are done before moving on. Going into this function, we should
450 * not have processes doing IO to this device.
454 del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
455 mutex_lock(&q->sysfs_lock);
456 queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q);
457 mutex_unlock(&q->sysfs_lock);
460 elevator_exit(q->elevator);
464 EXPORT_SYMBOL(blk_cleanup_queue);
466 static int blk_init_free_list(struct request_queue *q)
468 struct request_list *rl = &q->rq;
470 if (unlikely(rl->rq_pool))
473 rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
474 rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
476 init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
477 init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
479 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
480 mempool_free_slab, request_cachep, q->node);
488 struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
490 return blk_alloc_queue_node(gfp_mask, -1);
492 EXPORT_SYMBOL(blk_alloc_queue);
494 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
496 struct request_queue *q;
499 q = kmem_cache_alloc_node(blk_requestq_cachep,
500 gfp_mask | __GFP_ZERO, node_id);
504 q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug;
505 q->backing_dev_info.unplug_io_data = q;
506 q->backing_dev_info.ra_pages =
507 (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
508 q->backing_dev_info.state = 0;
509 q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
510 q->backing_dev_info.name = "block";
512 err = bdi_init(&q->backing_dev_info);
514 kmem_cache_free(blk_requestq_cachep, q);
518 setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
519 laptop_mode_timer_fn, (unsigned long) q);
520 init_timer(&q->unplug_timer);
521 setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
522 INIT_LIST_HEAD(&q->timeout_list);
523 INIT_LIST_HEAD(&q->pending_barriers);
524 INIT_WORK(&q->unplug_work, blk_unplug_work);
526 kobject_init(&q->kobj, &blk_queue_ktype);
528 mutex_init(&q->sysfs_lock);
529 spin_lock_init(&q->__queue_lock);
533 EXPORT_SYMBOL(blk_alloc_queue_node);
536 * blk_init_queue - prepare a request queue for use with a block device
537 * @rfn: The function to be called to process requests that have been
538 * placed on the queue.
539 * @lock: Request queue spin lock
542 * If a block device wishes to use the standard request handling procedures,
543 * which sorts requests and coalesces adjacent requests, then it must
544 * call blk_init_queue(). The function @rfn will be called when there
545 * are requests on the queue that need to be processed. If the device
546 * supports plugging, then @rfn may not be called immediately when requests
547 * are available on the queue, but may be called at some time later instead.
548 * Plugged queues are generally unplugged when a buffer belonging to one
549 * of the requests on the queue is needed, or due to memory pressure.
551 * @rfn is not required, or even expected, to remove all requests off the
552 * queue, but only as many as it can handle at a time. If it does leave
553 * requests on the queue, it is responsible for arranging that the requests
554 * get dealt with eventually.
556 * The queue spin lock must be held while manipulating the requests on the
557 * request queue; this lock will be taken also from interrupt context, so irq
558 * disabling is needed for it.
560 * Function returns a pointer to the initialized request queue, or %NULL if
564 * blk_init_queue() must be paired with a blk_cleanup_queue() call
565 * when the block device is deactivated (such as at module unload).
568 struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
570 return blk_init_queue_node(rfn, lock, -1);
572 EXPORT_SYMBOL(blk_init_queue);
574 struct request_queue *
575 blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
577 struct request_queue *uninit_q, *q;
579 uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id);
583 q = blk_init_allocated_queue_node(uninit_q, rfn, lock, node_id);
585 blk_cleanup_queue(uninit_q);
589 EXPORT_SYMBOL(blk_init_queue_node);
591 struct request_queue *
592 blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
595 return blk_init_allocated_queue_node(q, rfn, lock, -1);
597 EXPORT_SYMBOL(blk_init_allocated_queue);
599 struct request_queue *
600 blk_init_allocated_queue_node(struct request_queue *q, request_fn_proc *rfn,
601 spinlock_t *lock, int node_id)
607 if (blk_init_free_list(q))
611 q->prep_rq_fn = NULL;
612 q->unprep_rq_fn = NULL;
613 q->unplug_fn = generic_unplug_device;
614 q->queue_flags = QUEUE_FLAG_DEFAULT;
615 q->queue_lock = lock;
618 * This also sets hw/phys segments, boundary and size
620 blk_queue_make_request(q, __make_request);
622 q->sg_reserved_size = INT_MAX;
627 if (!elevator_init(q, NULL)) {
628 blk_queue_congestion_threshold(q);
634 EXPORT_SYMBOL(blk_init_allocated_queue_node);
636 int blk_get_queue(struct request_queue *q)
638 if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
639 kobject_get(&q->kobj);
646 static inline void blk_free_request(struct request_queue *q, struct request *rq)
648 if (rq->cmd_flags & REQ_ELVPRIV)
649 elv_put_request(q, rq);
650 mempool_free(rq, q->rq.rq_pool);
653 static struct request *
654 blk_alloc_request(struct request_queue *q, int flags, int priv, gfp_t gfp_mask)
656 struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
663 rq->cmd_flags = flags | REQ_ALLOCED;
666 if (unlikely(elv_set_request(q, rq, gfp_mask))) {
667 mempool_free(rq, q->rq.rq_pool);
670 rq->cmd_flags |= REQ_ELVPRIV;
677 * ioc_batching returns true if the ioc is a valid batching request and
678 * should be given priority access to a request.
680 static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
686 * Make sure the process is able to allocate at least 1 request
687 * even if the batch times out, otherwise we could theoretically
690 return ioc->nr_batch_requests == q->nr_batching ||
691 (ioc->nr_batch_requests > 0
692 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
696 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
697 * will cause the process to be a "batcher" on all queues in the system. This
698 * is the behaviour we want though - once it gets a wakeup it should be given
701 static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
703 if (!ioc || ioc_batching(q, ioc))
706 ioc->nr_batch_requests = q->nr_batching;
707 ioc->last_waited = jiffies;
710 static void __freed_request(struct request_queue *q, int sync)
712 struct request_list *rl = &q->rq;
714 if (rl->count[sync] < queue_congestion_off_threshold(q))
715 blk_clear_queue_congested(q, sync);
717 if (rl->count[sync] + 1 <= q->nr_requests) {
718 if (waitqueue_active(&rl->wait[sync]))
719 wake_up(&rl->wait[sync]);
721 blk_clear_queue_full(q, sync);
726 * A request has just been released. Account for it, update the full and
727 * congestion status, wake up any waiters. Called under q->queue_lock.
729 static void freed_request(struct request_queue *q, int sync, int priv)
731 struct request_list *rl = &q->rq;
737 __freed_request(q, sync);
739 if (unlikely(rl->starved[sync ^ 1]))
740 __freed_request(q, sync ^ 1);
744 * Get a free request, queue_lock must be held.
745 * Returns NULL on failure, with queue_lock held.
746 * Returns !NULL on success, with queue_lock *not held*.
748 static struct request *get_request(struct request_queue *q, int rw_flags,
749 struct bio *bio, gfp_t gfp_mask)
751 struct request *rq = NULL;
752 struct request_list *rl = &q->rq;
753 struct io_context *ioc = NULL;
754 const bool is_sync = rw_is_sync(rw_flags) != 0;
757 may_queue = elv_may_queue(q, rw_flags);
758 if (may_queue == ELV_MQUEUE_NO)
761 if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
762 if (rl->count[is_sync]+1 >= q->nr_requests) {
763 ioc = current_io_context(GFP_ATOMIC, q->node);
765 * The queue will fill after this allocation, so set
766 * it as full, and mark this process as "batching".
767 * This process will be allowed to complete a batch of
768 * requests, others will be blocked.
770 if (!blk_queue_full(q, is_sync)) {
771 ioc_set_batching(q, ioc);
772 blk_set_queue_full(q, is_sync);
774 if (may_queue != ELV_MQUEUE_MUST
775 && !ioc_batching(q, ioc)) {
777 * The queue is full and the allocating
778 * process is not a "batcher", and not
779 * exempted by the IO scheduler
785 blk_set_queue_congested(q, is_sync);
789 * Only allow batching queuers to allocate up to 50% over the defined
790 * limit of requests, otherwise we could have thousands of requests
791 * allocated with any setting of ->nr_requests
793 if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
796 rl->count[is_sync]++;
797 rl->starved[is_sync] = 0;
799 priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
803 if (blk_queue_io_stat(q))
804 rw_flags |= REQ_IO_STAT;
805 spin_unlock_irq(q->queue_lock);
807 rq = blk_alloc_request(q, rw_flags, priv, gfp_mask);
810 * Allocation failed presumably due to memory. Undo anything
811 * we might have messed up.
813 * Allocating task should really be put onto the front of the
814 * wait queue, but this is pretty rare.
816 spin_lock_irq(q->queue_lock);
817 freed_request(q, is_sync, priv);
820 * in the very unlikely event that allocation failed and no
821 * requests for this direction was pending, mark us starved
822 * so that freeing of a request in the other direction will
823 * notice us. another possible fix would be to split the
824 * rq mempool into READ and WRITE
827 if (unlikely(rl->count[is_sync] == 0))
828 rl->starved[is_sync] = 1;
834 * ioc may be NULL here, and ioc_batching will be false. That's
835 * OK, if the queue is under the request limit then requests need
836 * not count toward the nr_batch_requests limit. There will always
837 * be some limit enforced by BLK_BATCH_TIME.
839 if (ioc_batching(q, ioc))
840 ioc->nr_batch_requests--;
842 trace_block_getrq(q, bio, rw_flags & 1);
848 * No available requests for this queue, unplug the device and wait for some
849 * requests to become available.
851 * Called with q->queue_lock held, and returns with it unlocked.
853 static struct request *get_request_wait(struct request_queue *q, int rw_flags,
856 const bool is_sync = rw_is_sync(rw_flags) != 0;
859 rq = get_request(q, rw_flags, bio, GFP_NOIO);
862 struct io_context *ioc;
863 struct request_list *rl = &q->rq;
865 prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
866 TASK_UNINTERRUPTIBLE);
868 trace_block_sleeprq(q, bio, rw_flags & 1);
870 __generic_unplug_device(q);
871 spin_unlock_irq(q->queue_lock);
875 * After sleeping, we become a "batching" process and
876 * will be able to allocate at least one request, and
877 * up to a big batch of them for a small period time.
878 * See ioc_batching, ioc_set_batching
880 ioc = current_io_context(GFP_NOIO, q->node);
881 ioc_set_batching(q, ioc);
883 spin_lock_irq(q->queue_lock);
884 finish_wait(&rl->wait[is_sync], &wait);
886 rq = get_request(q, rw_flags, bio, GFP_NOIO);
892 struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
896 BUG_ON(rw != READ && rw != WRITE);
898 spin_lock_irq(q->queue_lock);
899 if (gfp_mask & __GFP_WAIT) {
900 rq = get_request_wait(q, rw, NULL);
902 rq = get_request(q, rw, NULL, gfp_mask);
904 spin_unlock_irq(q->queue_lock);
906 /* q->queue_lock is unlocked at this point */
910 EXPORT_SYMBOL(blk_get_request);
913 * blk_make_request - given a bio, allocate a corresponding struct request.
914 * @q: target request queue
915 * @bio: The bio describing the memory mappings that will be submitted for IO.
916 * It may be a chained-bio properly constructed by block/bio layer.
917 * @gfp_mask: gfp flags to be used for memory allocation
919 * blk_make_request is the parallel of generic_make_request for BLOCK_PC
920 * type commands. Where the struct request needs to be farther initialized by
921 * the caller. It is passed a &struct bio, which describes the memory info of
924 * The caller of blk_make_request must make sure that bi_io_vec
925 * are set to describe the memory buffers. That bio_data_dir() will return
926 * the needed direction of the request. (And all bio's in the passed bio-chain
927 * are properly set accordingly)
929 * If called under none-sleepable conditions, mapped bio buffers must not
930 * need bouncing, by calling the appropriate masked or flagged allocator,
931 * suitable for the target device. Otherwise the call to blk_queue_bounce will
934 * WARNING: When allocating/cloning a bio-chain, careful consideration should be
935 * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for
936 * anything but the first bio in the chain. Otherwise you risk waiting for IO
937 * completion of a bio that hasn't been submitted yet, thus resulting in a
938 * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead
939 * of bio_alloc(), as that avoids the mempool deadlock.
940 * If possible a big IO should be split into smaller parts when allocation
941 * fails. Partial allocation should not be an error, or you risk a live-lock.
943 struct request *blk_make_request(struct request_queue *q, struct bio *bio,
946 struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask);
949 return ERR_PTR(-ENOMEM);
952 struct bio *bounce_bio = bio;
955 blk_queue_bounce(q, &bounce_bio);
956 ret = blk_rq_append_bio(q, rq, bounce_bio);
965 EXPORT_SYMBOL(blk_make_request);
968 * blk_requeue_request - put a request back on queue
969 * @q: request queue where request should be inserted
970 * @rq: request to be inserted
973 * Drivers often keep queueing requests until the hardware cannot accept
974 * more, when that condition happens we need to put the request back
975 * on the queue. Must be called with queue lock held.
977 void blk_requeue_request(struct request_queue *q, struct request *rq)
979 blk_delete_timer(rq);
980 blk_clear_rq_complete(rq);
981 trace_block_rq_requeue(q, rq);
983 if (blk_rq_tagged(rq))
984 blk_queue_end_tag(q, rq);
986 BUG_ON(blk_queued_rq(rq));
988 elv_requeue_request(q, rq);
990 EXPORT_SYMBOL(blk_requeue_request);
993 * blk_insert_request - insert a special request into a request queue
994 * @q: request queue where request should be inserted
995 * @rq: request to be inserted
996 * @at_head: insert request at head or tail of queue
997 * @data: private data
1000 * Many block devices need to execute commands asynchronously, so they don't
1001 * block the whole kernel from preemption during request execution. This is
1002 * accomplished normally by inserting aritficial requests tagged as
1003 * REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them
1004 * be scheduled for actual execution by the request queue.
1006 * We have the option of inserting the head or the tail of the queue.
1007 * Typically we use the tail for new ioctls and so forth. We use the head
1008 * of the queue for things like a QUEUE_FULL message from a device, or a
1009 * host that is unable to accept a particular command.
1011 void blk_insert_request(struct request_queue *q, struct request *rq,
1012 int at_head, void *data)
1014 int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
1015 unsigned long flags;
1018 * tell I/O scheduler that this isn't a regular read/write (ie it
1019 * must not attempt merges on this) and that it acts as a soft
1022 rq->cmd_type = REQ_TYPE_SPECIAL;
1026 spin_lock_irqsave(q->queue_lock, flags);
1029 * If command is tagged, release the tag
1031 if (blk_rq_tagged(rq))
1032 blk_queue_end_tag(q, rq);
1034 drive_stat_acct(rq, 1);
1035 __elv_add_request(q, rq, where, 0);
1037 spin_unlock_irqrestore(q->queue_lock, flags);
1039 EXPORT_SYMBOL(blk_insert_request);
1041 static void part_round_stats_single(int cpu, struct hd_struct *part,
1044 if (now == part->stamp)
1047 if (part_in_flight(part)) {
1048 __part_stat_add(cpu, part, time_in_queue,
1049 part_in_flight(part) * (now - part->stamp));
1050 __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
1056 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1057 * @cpu: cpu number for stats access
1058 * @part: target partition
1060 * The average IO queue length and utilisation statistics are maintained
1061 * by observing the current state of the queue length and the amount of
1062 * time it has been in this state for.
1064 * Normally, that accounting is done on IO completion, but that can result
1065 * in more than a second's worth of IO being accounted for within any one
1066 * second, leading to >100% utilisation. To deal with that, we call this
1067 * function to do a round-off before returning the results when reading
1068 * /proc/diskstats. This accounts immediately for all queue usage up to
1069 * the current jiffies and restarts the counters again.
1071 void part_round_stats(int cpu, struct hd_struct *part)
1073 unsigned long now = jiffies;
1076 part_round_stats_single(cpu, &part_to_disk(part)->part0, now);
1077 part_round_stats_single(cpu, part, now);
1079 EXPORT_SYMBOL_GPL(part_round_stats);
1082 * queue lock must be held
1084 void __blk_put_request(struct request_queue *q, struct request *req)
1088 if (unlikely(--req->ref_count))
1091 elv_completed_request(q, req);
1093 /* this is a bio leak */
1094 WARN_ON(req->bio != NULL);
1097 * Request may not have originated from ll_rw_blk. if not,
1098 * it didn't come out of our reserved rq pools
1100 if (req->cmd_flags & REQ_ALLOCED) {
1101 int is_sync = rq_is_sync(req) != 0;
1102 int priv = req->cmd_flags & REQ_ELVPRIV;
1104 BUG_ON(!list_empty(&req->queuelist));
1105 BUG_ON(!hlist_unhashed(&req->hash));
1107 blk_free_request(q, req);
1108 freed_request(q, is_sync, priv);
1111 EXPORT_SYMBOL_GPL(__blk_put_request);
1113 void blk_put_request(struct request *req)
1115 unsigned long flags;
1116 struct request_queue *q = req->q;
1118 spin_lock_irqsave(q->queue_lock, flags);
1119 __blk_put_request(q, req);
1120 spin_unlock_irqrestore(q->queue_lock, flags);
1122 EXPORT_SYMBOL(blk_put_request);
1125 * blk_add_request_payload - add a payload to a request
1126 * @rq: request to update
1127 * @page: page backing the payload
1128 * @len: length of the payload.
1130 * This allows to later add a payload to an already submitted request by
1131 * a block driver. The driver needs to take care of freeing the payload
1134 * Note that this is a quite horrible hack and nothing but handling of
1135 * discard requests should ever use it.
1137 void blk_add_request_payload(struct request *rq, struct page *page,
1140 struct bio *bio = rq->bio;
1142 bio->bi_io_vec->bv_page = page;
1143 bio->bi_io_vec->bv_offset = 0;
1144 bio->bi_io_vec->bv_len = len;
1148 bio->bi_phys_segments = 1;
1150 rq->__data_len = rq->resid_len = len;
1151 rq->nr_phys_segments = 1;
1152 rq->buffer = bio_data(bio);
1154 EXPORT_SYMBOL_GPL(blk_add_request_payload);
1156 void init_request_from_bio(struct request *req, struct bio *bio)
1158 req->cpu = bio->bi_comp_cpu;
1159 req->cmd_type = REQ_TYPE_FS;
1161 req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK;
1162 if (bio->bi_rw & REQ_RAHEAD)
1163 req->cmd_flags |= REQ_FAILFAST_MASK;
1166 req->__sector = bio->bi_sector;
1167 req->ioprio = bio_prio(bio);
1168 blk_rq_bio_prep(req->q, req, bio);
1172 * Only disabling plugging for non-rotational devices if it does tagging
1173 * as well, otherwise we do need the proper merging
1175 static inline bool queue_should_plug(struct request_queue *q)
1177 return !(blk_queue_nonrot(q) && blk_queue_tagged(q));
1180 static int __make_request(struct request_queue *q, struct bio *bio)
1182 struct request *req;
1184 unsigned int bytes = bio->bi_size;
1185 const unsigned short prio = bio_prio(bio);
1186 const bool sync = (bio->bi_rw & REQ_SYNC);
1187 const bool unplug = (bio->bi_rw & REQ_UNPLUG);
1188 const unsigned int ff = bio->bi_rw & REQ_FAILFAST_MASK;
1189 int where = ELEVATOR_INSERT_SORT;
1192 /* REQ_HARDBARRIER is no more */
1193 if (WARN_ONCE(bio->bi_rw & REQ_HARDBARRIER,
1194 "block: HARDBARRIER is deprecated, use FLUSH/FUA instead\n")) {
1195 bio_endio(bio, -EOPNOTSUPP);
1200 * low level driver can indicate that it wants pages above a
1201 * certain limit bounced to low memory (ie for highmem, or even
1202 * ISA dma in theory)
1204 blk_queue_bounce(q, &bio);
1206 spin_lock_irq(q->queue_lock);
1208 if (bio->bi_rw & REQ_HARDBARRIER) {
1209 where = ELEVATOR_INSERT_FRONT;
1213 if (elv_queue_empty(q))
1216 el_ret = elv_merge(q, &req, bio);
1218 case ELEVATOR_BACK_MERGE:
1219 BUG_ON(!rq_mergeable(req));
1221 if (!ll_back_merge_fn(q, req, bio))
1224 trace_block_bio_backmerge(q, bio);
1226 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1227 blk_rq_set_mixed_merge(req);
1229 req->biotail->bi_next = bio;
1231 req->__data_len += bytes;
1232 req->ioprio = ioprio_best(req->ioprio, prio);
1233 if (!blk_rq_cpu_valid(req))
1234 req->cpu = bio->bi_comp_cpu;
1235 drive_stat_acct(req, 0);
1236 elv_bio_merged(q, req, bio);
1237 if (!attempt_back_merge(q, req))
1238 elv_merged_request(q, req, el_ret);
1241 case ELEVATOR_FRONT_MERGE:
1242 BUG_ON(!rq_mergeable(req));
1244 if (!ll_front_merge_fn(q, req, bio))
1247 trace_block_bio_frontmerge(q, bio);
1249 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) {
1250 blk_rq_set_mixed_merge(req);
1251 req->cmd_flags &= ~REQ_FAILFAST_MASK;
1252 req->cmd_flags |= ff;
1255 bio->bi_next = req->bio;
1259 * may not be valid. if the low level driver said
1260 * it didn't need a bounce buffer then it better
1261 * not touch req->buffer either...
1263 req->buffer = bio_data(bio);
1264 req->__sector = bio->bi_sector;
1265 req->__data_len += bytes;
1266 req->ioprio = ioprio_best(req->ioprio, prio);
1267 if (!blk_rq_cpu_valid(req))
1268 req->cpu = bio->bi_comp_cpu;
1269 drive_stat_acct(req, 0);
1270 elv_bio_merged(q, req, bio);
1271 if (!attempt_front_merge(q, req))
1272 elv_merged_request(q, req, el_ret);
1275 /* ELV_NO_MERGE: elevator says don't/can't merge. */
1282 * This sync check and mask will be re-done in init_request_from_bio(),
1283 * but we need to set it earlier to expose the sync flag to the
1284 * rq allocator and io schedulers.
1286 rw_flags = bio_data_dir(bio);
1288 rw_flags |= REQ_SYNC;
1291 * Grab a free request. This is might sleep but can not fail.
1292 * Returns with the queue unlocked.
1294 req = get_request_wait(q, rw_flags, bio);
1297 * After dropping the lock and possibly sleeping here, our request
1298 * may now be mergeable after it had proven unmergeable (above).
1299 * We don't worry about that case for efficiency. It won't happen
1300 * often, and the elevators are able to handle it.
1302 init_request_from_bio(req, bio);
1304 spin_lock_irq(q->queue_lock);
1305 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) ||
1306 bio_flagged(bio, BIO_CPU_AFFINE))
1307 req->cpu = blk_cpu_to_group(smp_processor_id());
1308 if (queue_should_plug(q) && elv_queue_empty(q))
1311 /* insert the request into the elevator */
1312 drive_stat_acct(req, 1);
1313 __elv_add_request(q, req, where, 0);
1315 if (unplug || !queue_should_plug(q))
1316 __generic_unplug_device(q);
1317 spin_unlock_irq(q->queue_lock);
1322 * If bio->bi_dev is a partition, remap the location
1324 static inline void blk_partition_remap(struct bio *bio)
1326 struct block_device *bdev = bio->bi_bdev;
1328 if (bio_sectors(bio) && bdev != bdev->bd_contains) {
1329 struct hd_struct *p = bdev->bd_part;
1331 bio->bi_sector += p->start_sect;
1332 bio->bi_bdev = bdev->bd_contains;
1334 trace_block_remap(bdev_get_queue(bio->bi_bdev), bio,
1336 bio->bi_sector - p->start_sect);
1340 static void handle_bad_sector(struct bio *bio)
1342 char b[BDEVNAME_SIZE];
1344 printk(KERN_INFO "attempt to access beyond end of device\n");
1345 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
1346 bdevname(bio->bi_bdev, b),
1348 (unsigned long long)bio->bi_sector + bio_sectors(bio),
1349 (long long)(bio->bi_bdev->bd_inode->i_size >> 9));
1351 set_bit(BIO_EOF, &bio->bi_flags);
1354 #ifdef CONFIG_FAIL_MAKE_REQUEST
1356 static DECLARE_FAULT_ATTR(fail_make_request);
1358 static int __init setup_fail_make_request(char *str)
1360 return setup_fault_attr(&fail_make_request, str);
1362 __setup("fail_make_request=", setup_fail_make_request);
1364 static int should_fail_request(struct bio *bio)
1366 struct hd_struct *part = bio->bi_bdev->bd_part;
1368 if (part_to_disk(part)->part0.make_it_fail || part->make_it_fail)
1369 return should_fail(&fail_make_request, bio->bi_size);
1374 static int __init fail_make_request_debugfs(void)
1376 return init_fault_attr_dentries(&fail_make_request,
1377 "fail_make_request");
1380 late_initcall(fail_make_request_debugfs);
1382 #else /* CONFIG_FAIL_MAKE_REQUEST */
1384 static inline int should_fail_request(struct bio *bio)
1389 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1392 * Check whether this bio extends beyond the end of the device.
1394 static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
1401 /* Test device or partition size, when known. */
1402 maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
1404 sector_t sector = bio->bi_sector;
1406 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
1408 * This may well happen - the kernel calls bread()
1409 * without checking the size of the device, e.g., when
1410 * mounting a device.
1412 handle_bad_sector(bio);
1421 * generic_make_request - hand a buffer to its device driver for I/O
1422 * @bio: The bio describing the location in memory and on the device.
1424 * generic_make_request() is used to make I/O requests of block
1425 * devices. It is passed a &struct bio, which describes the I/O that needs
1428 * generic_make_request() does not return any status. The
1429 * success/failure status of the request, along with notification of
1430 * completion, is delivered asynchronously through the bio->bi_end_io
1431 * function described (one day) else where.
1433 * The caller of generic_make_request must make sure that bi_io_vec
1434 * are set to describe the memory buffer, and that bi_dev and bi_sector are
1435 * set to describe the device address, and the
1436 * bi_end_io and optionally bi_private are set to describe how
1437 * completion notification should be signaled.
1439 * generic_make_request and the drivers it calls may use bi_next if this
1440 * bio happens to be merged with someone else, and may change bi_dev and
1441 * bi_sector for remaps as it sees fit. So the values of these fields
1442 * should NOT be depended on after the call to generic_make_request.
1444 static inline void __generic_make_request(struct bio *bio)
1446 struct request_queue *q;
1447 sector_t old_sector;
1448 int ret, nr_sectors = bio_sectors(bio);
1454 if (bio_check_eod(bio, nr_sectors))
1458 * Resolve the mapping until finished. (drivers are
1459 * still free to implement/resolve their own stacking
1460 * by explicitly returning 0)
1462 * NOTE: we don't repeat the blk_size check for each new device.
1463 * Stacking drivers are expected to know what they are doing.
1468 char b[BDEVNAME_SIZE];
1470 q = bdev_get_queue(bio->bi_bdev);
1473 "generic_make_request: Trying to access "
1474 "nonexistent block-device %s (%Lu)\n",
1475 bdevname(bio->bi_bdev, b),
1476 (long long) bio->bi_sector);
1480 if (unlikely(!(bio->bi_rw & REQ_DISCARD) &&
1481 nr_sectors > queue_max_hw_sectors(q))) {
1482 printk(KERN_ERR "bio too big device %s (%u > %u)\n",
1483 bdevname(bio->bi_bdev, b),
1485 queue_max_hw_sectors(q));
1489 if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
1492 if (should_fail_request(bio))
1496 * If this device has partitions, remap block n
1497 * of partition p to block n+start(p) of the disk.
1499 blk_partition_remap(bio);
1501 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio))
1504 if (old_sector != -1)
1505 trace_block_remap(q, bio, old_dev, old_sector);
1507 old_sector = bio->bi_sector;
1508 old_dev = bio->bi_bdev->bd_dev;
1510 if (bio_check_eod(bio, nr_sectors))
1513 if ((bio->bi_rw & REQ_DISCARD) &&
1514 (!blk_queue_discard(q) ||
1515 ((bio->bi_rw & REQ_SECURE) &&
1516 !blk_queue_secdiscard(q)))) {
1521 trace_block_bio_queue(q, bio);
1523 ret = q->make_request_fn(q, bio);
1529 bio_endio(bio, err);
1533 * We only want one ->make_request_fn to be active at a time,
1534 * else stack usage with stacked devices could be a problem.
1535 * So use current->bio_list to keep a list of requests
1536 * submited by a make_request_fn function.
1537 * current->bio_list is also used as a flag to say if
1538 * generic_make_request is currently active in this task or not.
1539 * If it is NULL, then no make_request is active. If it is non-NULL,
1540 * then a make_request is active, and new requests should be added
1543 void generic_make_request(struct bio *bio)
1545 struct bio_list bio_list_on_stack;
1547 if (current->bio_list) {
1548 /* make_request is active */
1549 bio_list_add(current->bio_list, bio);
1552 /* following loop may be a bit non-obvious, and so deserves some
1554 * Before entering the loop, bio->bi_next is NULL (as all callers
1555 * ensure that) so we have a list with a single bio.
1556 * We pretend that we have just taken it off a longer list, so
1557 * we assign bio_list to a pointer to the bio_list_on_stack,
1558 * thus initialising the bio_list of new bios to be
1559 * added. __generic_make_request may indeed add some more bios
1560 * through a recursive call to generic_make_request. If it
1561 * did, we find a non-NULL value in bio_list and re-enter the loop
1562 * from the top. In this case we really did just take the bio
1563 * of the top of the list (no pretending) and so remove it from
1564 * bio_list, and call into __generic_make_request again.
1566 * The loop was structured like this to make only one call to
1567 * __generic_make_request (which is important as it is large and
1568 * inlined) and to keep the structure simple.
1570 BUG_ON(bio->bi_next);
1571 bio_list_init(&bio_list_on_stack);
1572 current->bio_list = &bio_list_on_stack;
1574 __generic_make_request(bio);
1575 bio = bio_list_pop(current->bio_list);
1577 current->bio_list = NULL; /* deactivate */
1579 EXPORT_SYMBOL(generic_make_request);
1582 * submit_bio - submit a bio to the block device layer for I/O
1583 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
1584 * @bio: The &struct bio which describes the I/O
1586 * submit_bio() is very similar in purpose to generic_make_request(), and
1587 * uses that function to do most of the work. Both are fairly rough
1588 * interfaces; @bio must be presetup and ready for I/O.
1591 void submit_bio(int rw, struct bio *bio)
1593 int count = bio_sectors(bio);
1598 * If it's a regular read/write or a barrier with data attached,
1599 * go through the normal accounting stuff before submission.
1601 if (bio_has_data(bio) && !(rw & REQ_DISCARD)) {
1603 count_vm_events(PGPGOUT, count);
1605 task_io_account_read(bio->bi_size);
1606 count_vm_events(PGPGIN, count);
1609 if (unlikely(block_dump)) {
1610 char b[BDEVNAME_SIZE];
1611 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n",
1612 current->comm, task_pid_nr(current),
1613 (rw & WRITE) ? "WRITE" : "READ",
1614 (unsigned long long)bio->bi_sector,
1615 bdevname(bio->bi_bdev, b));
1619 generic_make_request(bio);
1621 EXPORT_SYMBOL(submit_bio);
1624 * blk_rq_check_limits - Helper function to check a request for the queue limit
1626 * @rq: the request being checked
1629 * @rq may have been made based on weaker limitations of upper-level queues
1630 * in request stacking drivers, and it may violate the limitation of @q.
1631 * Since the block layer and the underlying device driver trust @rq
1632 * after it is inserted to @q, it should be checked against @q before
1633 * the insertion using this generic function.
1635 * This function should also be useful for request stacking drivers
1636 * in some cases below, so export this fuction.
1637 * Request stacking drivers like request-based dm may change the queue
1638 * limits while requests are in the queue (e.g. dm's table swapping).
1639 * Such request stacking drivers should check those requests agaist
1640 * the new queue limits again when they dispatch those requests,
1641 * although such checkings are also done against the old queue limits
1642 * when submitting requests.
1644 int blk_rq_check_limits(struct request_queue *q, struct request *rq)
1646 if (rq->cmd_flags & REQ_DISCARD)
1649 if (blk_rq_sectors(rq) > queue_max_sectors(q) ||
1650 blk_rq_bytes(rq) > queue_max_hw_sectors(q) << 9) {
1651 printk(KERN_ERR "%s: over max size limit.\n", __func__);
1656 * queue's settings related to segment counting like q->bounce_pfn
1657 * may differ from that of other stacking queues.
1658 * Recalculate it to check the request correctly on this queue's
1661 blk_recalc_rq_segments(rq);
1662 if (rq->nr_phys_segments > queue_max_segments(q)) {
1663 printk(KERN_ERR "%s: over max segments limit.\n", __func__);
1669 EXPORT_SYMBOL_GPL(blk_rq_check_limits);
1672 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
1673 * @q: the queue to submit the request
1674 * @rq: the request being queued
1676 int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
1678 unsigned long flags;
1680 if (blk_rq_check_limits(q, rq))
1683 #ifdef CONFIG_FAIL_MAKE_REQUEST
1684 if (rq->rq_disk && rq->rq_disk->part0.make_it_fail &&
1685 should_fail(&fail_make_request, blk_rq_bytes(rq)))
1689 spin_lock_irqsave(q->queue_lock, flags);
1692 * Submitting request must be dequeued before calling this function
1693 * because it will be linked to another request_queue
1695 BUG_ON(blk_queued_rq(rq));
1697 drive_stat_acct(rq, 1);
1698 __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0);
1700 spin_unlock_irqrestore(q->queue_lock, flags);
1704 EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
1707 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
1708 * @rq: request to examine
1711 * A request could be merge of IOs which require different failure
1712 * handling. This function determines the number of bytes which
1713 * can be failed from the beginning of the request without
1714 * crossing into area which need to be retried further.
1717 * The number of bytes to fail.
1720 * queue_lock must be held.
1722 unsigned int blk_rq_err_bytes(const struct request *rq)
1724 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
1725 unsigned int bytes = 0;
1728 if (!(rq->cmd_flags & REQ_MIXED_MERGE))
1729 return blk_rq_bytes(rq);
1732 * Currently the only 'mixing' which can happen is between
1733 * different fastfail types. We can safely fail portions
1734 * which have all the failfast bits that the first one has -
1735 * the ones which are at least as eager to fail as the first
1738 for (bio = rq->bio; bio; bio = bio->bi_next) {
1739 if ((bio->bi_rw & ff) != ff)
1741 bytes += bio->bi_size;
1744 /* this could lead to infinite loop */
1745 BUG_ON(blk_rq_bytes(rq) && !bytes);
1748 EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
1750 static void blk_account_io_completion(struct request *req, unsigned int bytes)
1752 if (blk_do_io_stat(req)) {
1753 const int rw = rq_data_dir(req);
1754 struct hd_struct *part;
1757 cpu = part_stat_lock();
1758 part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req));
1759 part_stat_add(cpu, part, sectors[rw], bytes >> 9);
1764 static void blk_account_io_done(struct request *req)
1767 * Account IO completion. bar_rq isn't accounted as a normal
1768 * IO on queueing nor completion. Accounting the containing
1769 * request is enough.
1771 if (blk_do_io_stat(req) && req != &req->q->bar_rq) {
1772 unsigned long duration = jiffies - req->start_time;
1773 const int rw = rq_data_dir(req);
1774 struct hd_struct *part;
1777 cpu = part_stat_lock();
1778 part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req));
1780 part_stat_inc(cpu, part, ios[rw]);
1781 part_stat_add(cpu, part, ticks[rw], duration);
1782 part_round_stats(cpu, part);
1783 part_dec_in_flight(part, rw);
1790 * blk_peek_request - peek at the top of a request queue
1791 * @q: request queue to peek at
1794 * Return the request at the top of @q. The returned request
1795 * should be started using blk_start_request() before LLD starts
1799 * Pointer to the request at the top of @q if available. Null
1803 * queue_lock must be held.
1805 struct request *blk_peek_request(struct request_queue *q)
1810 while ((rq = __elv_next_request(q)) != NULL) {
1811 if (!(rq->cmd_flags & REQ_STARTED)) {
1813 * This is the first time the device driver
1814 * sees this request (possibly after
1815 * requeueing). Notify IO scheduler.
1817 if (rq->cmd_flags & REQ_SORTED)
1818 elv_activate_rq(q, rq);
1821 * just mark as started even if we don't start
1822 * it, a request that has been delayed should
1823 * not be passed by new incoming requests
1825 rq->cmd_flags |= REQ_STARTED;
1826 trace_block_rq_issue(q, rq);
1829 if (!q->boundary_rq || q->boundary_rq == rq) {
1830 q->end_sector = rq_end_sector(rq);
1831 q->boundary_rq = NULL;
1834 if (rq->cmd_flags & REQ_DONTPREP)
1837 if (q->dma_drain_size && blk_rq_bytes(rq)) {
1839 * make sure space for the drain appears we
1840 * know we can do this because max_hw_segments
1841 * has been adjusted to be one fewer than the
1844 rq->nr_phys_segments++;
1850 ret = q->prep_rq_fn(q, rq);
1851 if (ret == BLKPREP_OK) {
1853 } else if (ret == BLKPREP_DEFER) {
1855 * the request may have been (partially) prepped.
1856 * we need to keep this request in the front to
1857 * avoid resource deadlock. REQ_STARTED will
1858 * prevent other fs requests from passing this one.
1860 if (q->dma_drain_size && blk_rq_bytes(rq) &&
1861 !(rq->cmd_flags & REQ_DONTPREP)) {
1863 * remove the space for the drain we added
1864 * so that we don't add it again
1866 --rq->nr_phys_segments;
1871 } else if (ret == BLKPREP_KILL) {
1872 rq->cmd_flags |= REQ_QUIET;
1874 * Mark this request as started so we don't trigger
1875 * any debug logic in the end I/O path.
1877 blk_start_request(rq);
1878 __blk_end_request_all(rq, -EIO);
1880 printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
1887 EXPORT_SYMBOL(blk_peek_request);
1889 void blk_dequeue_request(struct request *rq)
1891 struct request_queue *q = rq->q;
1893 BUG_ON(list_empty(&rq->queuelist));
1894 BUG_ON(ELV_ON_HASH(rq));
1896 list_del_init(&rq->queuelist);
1899 * the time frame between a request being removed from the lists
1900 * and to it is freed is accounted as io that is in progress at
1903 if (blk_account_rq(rq)) {
1904 q->in_flight[rq_is_sync(rq)]++;
1905 set_io_start_time_ns(rq);
1910 * blk_start_request - start request processing on the driver
1911 * @req: request to dequeue
1914 * Dequeue @req and start timeout timer on it. This hands off the
1915 * request to the driver.
1917 * Block internal functions which don't want to start timer should
1918 * call blk_dequeue_request().
1921 * queue_lock must be held.
1923 void blk_start_request(struct request *req)
1925 blk_dequeue_request(req);
1928 * We are now handing the request to the hardware, initialize
1929 * resid_len to full count and add the timeout handler.
1931 req->resid_len = blk_rq_bytes(req);
1932 if (unlikely(blk_bidi_rq(req)))
1933 req->next_rq->resid_len = blk_rq_bytes(req->next_rq);
1937 EXPORT_SYMBOL(blk_start_request);
1940 * blk_fetch_request - fetch a request from a request queue
1941 * @q: request queue to fetch a request from
1944 * Return the request at the top of @q. The request is started on
1945 * return and LLD can start processing it immediately.
1948 * Pointer to the request at the top of @q if available. Null
1952 * queue_lock must be held.
1954 struct request *blk_fetch_request(struct request_queue *q)
1958 rq = blk_peek_request(q);
1960 blk_start_request(rq);
1963 EXPORT_SYMBOL(blk_fetch_request);
1966 * blk_update_request - Special helper function for request stacking drivers
1967 * @req: the request being processed
1968 * @error: %0 for success, < %0 for error
1969 * @nr_bytes: number of bytes to complete @req
1972 * Ends I/O on a number of bytes attached to @req, but doesn't complete
1973 * the request structure even if @req doesn't have leftover.
1974 * If @req has leftover, sets it up for the next range of segments.
1976 * This special helper function is only for request stacking drivers
1977 * (e.g. request-based dm) so that they can handle partial completion.
1978 * Actual device drivers should use blk_end_request instead.
1980 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
1981 * %false return from this function.
1984 * %false - this request doesn't have any more data
1985 * %true - this request has more data
1987 bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
1989 int total_bytes, bio_nbytes, next_idx = 0;
1995 trace_block_rq_complete(req->q, req);
1998 * For fs requests, rq is just carrier of independent bio's
1999 * and each partial completion should be handled separately.
2000 * Reset per-request error on each partial completion.
2002 * TODO: tj: This is too subtle. It would be better to let
2003 * low level drivers do what they see fit.
2005 if (req->cmd_type == REQ_TYPE_FS)
2008 if (error && req->cmd_type == REQ_TYPE_FS &&
2009 !(req->cmd_flags & REQ_QUIET)) {
2010 printk(KERN_ERR "end_request: I/O error, dev %s, sector %llu\n",
2011 req->rq_disk ? req->rq_disk->disk_name : "?",
2012 (unsigned long long)blk_rq_pos(req));
2015 blk_account_io_completion(req, nr_bytes);
2017 total_bytes = bio_nbytes = 0;
2018 while ((bio = req->bio) != NULL) {
2021 if (nr_bytes >= bio->bi_size) {
2022 req->bio = bio->bi_next;
2023 nbytes = bio->bi_size;
2024 req_bio_endio(req, bio, nbytes, error);
2028 int idx = bio->bi_idx + next_idx;
2030 if (unlikely(idx >= bio->bi_vcnt)) {
2031 blk_dump_rq_flags(req, "__end_that");
2032 printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n",
2033 __func__, idx, bio->bi_vcnt);
2037 nbytes = bio_iovec_idx(bio, idx)->bv_len;
2038 BIO_BUG_ON(nbytes > bio->bi_size);
2041 * not a complete bvec done
2043 if (unlikely(nbytes > nr_bytes)) {
2044 bio_nbytes += nr_bytes;
2045 total_bytes += nr_bytes;
2050 * advance to the next vector
2053 bio_nbytes += nbytes;
2056 total_bytes += nbytes;
2062 * end more in this run, or just return 'not-done'
2064 if (unlikely(nr_bytes <= 0))
2074 * Reset counters so that the request stacking driver
2075 * can find how many bytes remain in the request
2078 req->__data_len = 0;
2083 * if the request wasn't completed, update state
2086 req_bio_endio(req, bio, bio_nbytes, error);
2087 bio->bi_idx += next_idx;
2088 bio_iovec(bio)->bv_offset += nr_bytes;
2089 bio_iovec(bio)->bv_len -= nr_bytes;
2092 req->__data_len -= total_bytes;
2093 req->buffer = bio_data(req->bio);
2095 /* update sector only for requests with clear definition of sector */
2096 if (req->cmd_type == REQ_TYPE_FS || (req->cmd_flags & REQ_DISCARD))
2097 req->__sector += total_bytes >> 9;
2099 /* mixed attributes always follow the first bio */
2100 if (req->cmd_flags & REQ_MIXED_MERGE) {
2101 req->cmd_flags &= ~REQ_FAILFAST_MASK;
2102 req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK;
2106 * If total number of sectors is less than the first segment
2107 * size, something has gone terribly wrong.
2109 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
2110 printk(KERN_ERR "blk: request botched\n");
2111 req->__data_len = blk_rq_cur_bytes(req);
2114 /* recalculate the number of segments */
2115 blk_recalc_rq_segments(req);
2119 EXPORT_SYMBOL_GPL(blk_update_request);
2121 static bool blk_update_bidi_request(struct request *rq, int error,
2122 unsigned int nr_bytes,
2123 unsigned int bidi_bytes)
2125 if (blk_update_request(rq, error, nr_bytes))
2128 /* Bidi request must be completed as a whole */
2129 if (unlikely(blk_bidi_rq(rq)) &&
2130 blk_update_request(rq->next_rq, error, bidi_bytes))
2133 if (blk_queue_add_random(rq->q))
2134 add_disk_randomness(rq->rq_disk);
2140 * blk_unprep_request - unprepare a request
2143 * This function makes a request ready for complete resubmission (or
2144 * completion). It happens only after all error handling is complete,
2145 * so represents the appropriate moment to deallocate any resources
2146 * that were allocated to the request in the prep_rq_fn. The queue
2147 * lock is held when calling this.
2149 void blk_unprep_request(struct request *req)
2151 struct request_queue *q = req->q;
2153 req->cmd_flags &= ~REQ_DONTPREP;
2154 if (q->unprep_rq_fn)
2155 q->unprep_rq_fn(q, req);
2157 EXPORT_SYMBOL_GPL(blk_unprep_request);
2160 * queue lock must be held
2162 static void blk_finish_request(struct request *req, int error)
2164 if (blk_rq_tagged(req))
2165 blk_queue_end_tag(req->q, req);
2167 BUG_ON(blk_queued_rq(req));
2169 if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS)
2170 laptop_io_completion(&req->q->backing_dev_info);
2172 blk_delete_timer(req);
2174 if (req->cmd_flags & REQ_DONTPREP)
2175 blk_unprep_request(req);
2178 blk_account_io_done(req);
2181 req->end_io(req, error);
2183 if (blk_bidi_rq(req))
2184 __blk_put_request(req->next_rq->q, req->next_rq);
2186 __blk_put_request(req->q, req);
2191 * blk_end_bidi_request - Complete a bidi request
2192 * @rq: the request to complete
2193 * @error: %0 for success, < %0 for error
2194 * @nr_bytes: number of bytes to complete @rq
2195 * @bidi_bytes: number of bytes to complete @rq->next_rq
2198 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2199 * Drivers that supports bidi can safely call this member for any
2200 * type of request, bidi or uni. In the later case @bidi_bytes is
2204 * %false - we are done with this request
2205 * %true - still buffers pending for this request
2207 static bool blk_end_bidi_request(struct request *rq, int error,
2208 unsigned int nr_bytes, unsigned int bidi_bytes)
2210 struct request_queue *q = rq->q;
2211 unsigned long flags;
2213 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2216 spin_lock_irqsave(q->queue_lock, flags);
2217 blk_finish_request(rq, error);
2218 spin_unlock_irqrestore(q->queue_lock, flags);
2224 * __blk_end_bidi_request - Complete a bidi request with queue lock held
2225 * @rq: the request to complete
2226 * @error: %0 for success, < %0 for error
2227 * @nr_bytes: number of bytes to complete @rq
2228 * @bidi_bytes: number of bytes to complete @rq->next_rq
2231 * Identical to blk_end_bidi_request() except that queue lock is
2232 * assumed to be locked on entry and remains so on return.
2235 * %false - we are done with this request
2236 * %true - still buffers pending for this request
2238 static bool __blk_end_bidi_request(struct request *rq, int error,
2239 unsigned int nr_bytes, unsigned int bidi_bytes)
2241 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2244 blk_finish_request(rq, error);
2250 * blk_end_request - Helper function for drivers to complete the request.
2251 * @rq: the request being processed
2252 * @error: %0 for success, < %0 for error
2253 * @nr_bytes: number of bytes to complete
2256 * Ends I/O on a number of bytes attached to @rq.
2257 * If @rq has leftover, sets it up for the next range of segments.
2260 * %false - we are done with this request
2261 * %true - still buffers pending for this request
2263 bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
2265 return blk_end_bidi_request(rq, error, nr_bytes, 0);
2267 EXPORT_SYMBOL(blk_end_request);
2270 * blk_end_request_all - Helper function for drives to finish the request.
2271 * @rq: the request to finish
2272 * @error: %0 for success, < %0 for error
2275 * Completely finish @rq.
2277 void blk_end_request_all(struct request *rq, int error)
2280 unsigned int bidi_bytes = 0;
2282 if (unlikely(blk_bidi_rq(rq)))
2283 bidi_bytes = blk_rq_bytes(rq->next_rq);
2285 pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2288 EXPORT_SYMBOL(blk_end_request_all);
2291 * blk_end_request_cur - Helper function to finish the current request chunk.
2292 * @rq: the request to finish the current chunk for
2293 * @error: %0 for success, < %0 for error
2296 * Complete the current consecutively mapped chunk from @rq.
2299 * %false - we are done with this request
2300 * %true - still buffers pending for this request
2302 bool blk_end_request_cur(struct request *rq, int error)
2304 return blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2306 EXPORT_SYMBOL(blk_end_request_cur);
2309 * blk_end_request_err - Finish a request till the next failure boundary.
2310 * @rq: the request to finish till the next failure boundary for
2311 * @error: must be negative errno
2314 * Complete @rq till the next failure boundary.
2317 * %false - we are done with this request
2318 * %true - still buffers pending for this request
2320 bool blk_end_request_err(struct request *rq, int error)
2322 WARN_ON(error >= 0);
2323 return blk_end_request(rq, error, blk_rq_err_bytes(rq));
2325 EXPORT_SYMBOL_GPL(blk_end_request_err);
2328 * __blk_end_request - Helper function for drivers to complete the request.
2329 * @rq: the request being processed
2330 * @error: %0 for success, < %0 for error
2331 * @nr_bytes: number of bytes to complete
2334 * Must be called with queue lock held unlike blk_end_request().
2337 * %false - we are done with this request
2338 * %true - still buffers pending for this request
2340 bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
2342 return __blk_end_bidi_request(rq, error, nr_bytes, 0);
2344 EXPORT_SYMBOL(__blk_end_request);
2347 * __blk_end_request_all - Helper function for drives to finish the request.
2348 * @rq: the request to finish
2349 * @error: %0 for success, < %0 for error
2352 * Completely finish @rq. Must be called with queue lock held.
2354 void __blk_end_request_all(struct request *rq, int error)
2357 unsigned int bidi_bytes = 0;
2359 if (unlikely(blk_bidi_rq(rq)))
2360 bidi_bytes = blk_rq_bytes(rq->next_rq);
2362 pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2365 EXPORT_SYMBOL(__blk_end_request_all);
2368 * __blk_end_request_cur - Helper function to finish the current request chunk.
2369 * @rq: the request to finish the current chunk for
2370 * @error: %0 for success, < %0 for error
2373 * Complete the current consecutively mapped chunk from @rq. Must
2374 * be called with queue lock held.
2377 * %false - we are done with this request
2378 * %true - still buffers pending for this request
2380 bool __blk_end_request_cur(struct request *rq, int error)
2382 return __blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2384 EXPORT_SYMBOL(__blk_end_request_cur);
2387 * __blk_end_request_err - Finish a request till the next failure boundary.
2388 * @rq: the request to finish till the next failure boundary for
2389 * @error: must be negative errno
2392 * Complete @rq till the next failure boundary. Must be called
2393 * with queue lock held.
2396 * %false - we are done with this request
2397 * %true - still buffers pending for this request
2399 bool __blk_end_request_err(struct request *rq, int error)
2401 WARN_ON(error >= 0);
2402 return __blk_end_request(rq, error, blk_rq_err_bytes(rq));
2404 EXPORT_SYMBOL_GPL(__blk_end_request_err);
2406 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
2409 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */
2410 rq->cmd_flags |= bio->bi_rw & REQ_WRITE;
2412 if (bio_has_data(bio)) {
2413 rq->nr_phys_segments = bio_phys_segments(q, bio);
2414 rq->buffer = bio_data(bio);
2416 rq->__data_len = bio->bi_size;
2417 rq->bio = rq->biotail = bio;
2420 rq->rq_disk = bio->bi_bdev->bd_disk;
2423 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
2425 * rq_flush_dcache_pages - Helper function to flush all pages in a request
2426 * @rq: the request to be flushed
2429 * Flush all pages in @rq.
2431 void rq_flush_dcache_pages(struct request *rq)
2433 struct req_iterator iter;
2434 struct bio_vec *bvec;
2436 rq_for_each_segment(bvec, rq, iter)
2437 flush_dcache_page(bvec->bv_page);
2439 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
2443 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
2444 * @q : the queue of the device being checked
2447 * Check if underlying low-level drivers of a device are busy.
2448 * If the drivers want to export their busy state, they must set own
2449 * exporting function using blk_queue_lld_busy() first.
2451 * Basically, this function is used only by request stacking drivers
2452 * to stop dispatching requests to underlying devices when underlying
2453 * devices are busy. This behavior helps more I/O merging on the queue
2454 * of the request stacking driver and prevents I/O throughput regression
2455 * on burst I/O load.
2458 * 0 - Not busy (The request stacking driver should dispatch request)
2459 * 1 - Busy (The request stacking driver should stop dispatching request)
2461 int blk_lld_busy(struct request_queue *q)
2464 return q->lld_busy_fn(q);
2468 EXPORT_SYMBOL_GPL(blk_lld_busy);
2471 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
2472 * @rq: the clone request to be cleaned up
2475 * Free all bios in @rq for a cloned request.
2477 void blk_rq_unprep_clone(struct request *rq)
2481 while ((bio = rq->bio) != NULL) {
2482 rq->bio = bio->bi_next;
2487 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
2490 * Copy attributes of the original request to the clone request.
2491 * The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied.
2493 static void __blk_rq_prep_clone(struct request *dst, struct request *src)
2495 dst->cpu = src->cpu;
2496 dst->cmd_flags = (rq_data_dir(src) | REQ_NOMERGE);
2497 if (src->cmd_flags & REQ_DISCARD)
2498 dst->cmd_flags |= REQ_DISCARD;
2499 dst->cmd_type = src->cmd_type;
2500 dst->__sector = blk_rq_pos(src);
2501 dst->__data_len = blk_rq_bytes(src);
2502 dst->nr_phys_segments = src->nr_phys_segments;
2503 dst->ioprio = src->ioprio;
2504 dst->extra_len = src->extra_len;
2508 * blk_rq_prep_clone - Helper function to setup clone request
2509 * @rq: the request to be setup
2510 * @rq_src: original request to be cloned
2511 * @bs: bio_set that bios for clone are allocated from
2512 * @gfp_mask: memory allocation mask for bio
2513 * @bio_ctr: setup function to be called for each clone bio.
2514 * Returns %0 for success, non %0 for failure.
2515 * @data: private data to be passed to @bio_ctr
2518 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
2519 * The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense)
2520 * are not copied, and copying such parts is the caller's responsibility.
2521 * Also, pages which the original bios are pointing to are not copied
2522 * and the cloned bios just point same pages.
2523 * So cloned bios must be completed before original bios, which means
2524 * the caller must complete @rq before @rq_src.
2526 int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
2527 struct bio_set *bs, gfp_t gfp_mask,
2528 int (*bio_ctr)(struct bio *, struct bio *, void *),
2531 struct bio *bio, *bio_src;
2536 blk_rq_init(NULL, rq);
2538 __rq_for_each_bio(bio_src, rq_src) {
2539 bio = bio_alloc_bioset(gfp_mask, bio_src->bi_max_vecs, bs);
2543 __bio_clone(bio, bio_src);
2545 if (bio_integrity(bio_src) &&
2546 bio_integrity_clone(bio, bio_src, gfp_mask, bs))
2549 if (bio_ctr && bio_ctr(bio, bio_src, data))
2553 rq->biotail->bi_next = bio;
2556 rq->bio = rq->biotail = bio;
2559 __blk_rq_prep_clone(rq, rq_src);
2566 blk_rq_unprep_clone(rq);
2570 EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
2572 int kblockd_schedule_work(struct request_queue *q, struct work_struct *work)
2574 return queue_work(kblockd_workqueue, work);
2576 EXPORT_SYMBOL(kblockd_schedule_work);
2578 int __init blk_dev_init(void)
2580 BUILD_BUG_ON(__REQ_NR_BITS > 8 *
2581 sizeof(((struct request *)0)->cmd_flags));
2583 kblockd_workqueue = create_workqueue("kblockd");
2584 if (!kblockd_workqueue)
2585 panic("Failed to create kblockd\n");
2587 request_cachep = kmem_cache_create("blkdev_requests",
2588 sizeof(struct request), 0, SLAB_PANIC, NULL);
2590 blk_requestq_cachep = kmem_cache_create("blkdev_queue",
2591 sizeof(struct request_queue), 0, SLAB_PANIC, NULL);