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/blk-mq.h>
20 #include <linux/highmem.h>
22 #include <linux/kernel_stat.h>
23 #include <linux/string.h>
24 #include <linux/init.h>
25 #include <linux/completion.h>
26 #include <linux/slab.h>
27 #include <linux/swap.h>
28 #include <linux/writeback.h>
29 #include <linux/task_io_accounting_ops.h>
30 #include <linux/fault-inject.h>
31 #include <linux/list_sort.h>
32 #include <linux/delay.h>
33 #include <linux/ratelimit.h>
34 #include <linux/pm_runtime.h>
35 #include <linux/blk-cgroup.h>
37 #define CREATE_TRACE_POINTS
38 #include <trace/events/block.h>
43 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
44 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
45 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
46 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split);
47 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
49 DEFINE_IDA(blk_queue_ida);
52 * For the allocated request tables
54 struct kmem_cache *request_cachep = NULL;
57 * For queue allocation
59 struct kmem_cache *blk_requestq_cachep;
62 * Controlling structure to kblockd
64 static struct workqueue_struct *kblockd_workqueue;
66 static void blk_clear_congested(struct request_list *rl, int sync)
68 #ifdef CONFIG_CGROUP_WRITEBACK
69 clear_wb_congested(rl->blkg->wb_congested, sync);
72 * If !CGROUP_WRITEBACK, all blkg's map to bdi->wb and we shouldn't
73 * flip its congestion state for events on other blkcgs.
75 if (rl == &rl->q->root_rl)
76 clear_wb_congested(rl->q->backing_dev_info.wb.congested, sync);
80 static void blk_set_congested(struct request_list *rl, int sync)
82 #ifdef CONFIG_CGROUP_WRITEBACK
83 set_wb_congested(rl->blkg->wb_congested, sync);
85 /* see blk_clear_congested() */
86 if (rl == &rl->q->root_rl)
87 set_wb_congested(rl->q->backing_dev_info.wb.congested, sync);
91 void blk_queue_congestion_threshold(struct request_queue *q)
95 nr = q->nr_requests - (q->nr_requests / 8) + 1;
96 if (nr > q->nr_requests)
98 q->nr_congestion_on = nr;
100 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
103 q->nr_congestion_off = nr;
107 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
110 * Locates the passed device's request queue and returns the address of its
111 * backing_dev_info. This function can only be called if @bdev is opened
112 * and the return value is never NULL.
114 struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
116 struct request_queue *q = bdev_get_queue(bdev);
118 return &q->backing_dev_info;
120 EXPORT_SYMBOL(blk_get_backing_dev_info);
122 void blk_rq_init(struct request_queue *q, struct request *rq)
124 memset(rq, 0, sizeof(*rq));
126 INIT_LIST_HEAD(&rq->queuelist);
127 INIT_LIST_HEAD(&rq->timeout_list);
130 rq->__sector = (sector_t) -1;
131 INIT_HLIST_NODE(&rq->hash);
132 RB_CLEAR_NODE(&rq->rb_node);
134 rq->cmd_len = BLK_MAX_CDB;
136 rq->start_time = jiffies;
137 set_start_time_ns(rq);
140 EXPORT_SYMBOL(blk_rq_init);
142 static void req_bio_endio(struct request *rq, struct bio *bio,
143 unsigned int nbytes, int error)
146 bio->bi_error = error;
148 if (unlikely(rq->cmd_flags & REQ_QUIET))
149 bio_set_flag(bio, BIO_QUIET);
151 bio_advance(bio, nbytes);
153 /* don't actually finish bio if it's part of flush sequence */
154 if (bio->bi_iter.bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ))
158 void blk_dump_rq_flags(struct request *rq, char *msg)
162 printk(KERN_INFO "%s: dev %s: type=%x, flags=%llx\n", msg,
163 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
164 (unsigned long long) rq->cmd_flags);
166 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n",
167 (unsigned long long)blk_rq_pos(rq),
168 blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
169 printk(KERN_INFO " bio %p, biotail %p, len %u\n",
170 rq->bio, rq->biotail, blk_rq_bytes(rq));
172 if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
173 printk(KERN_INFO " cdb: ");
174 for (bit = 0; bit < BLK_MAX_CDB; bit++)
175 printk("%02x ", rq->cmd[bit]);
179 EXPORT_SYMBOL(blk_dump_rq_flags);
181 static void blk_delay_work(struct work_struct *work)
183 struct request_queue *q;
185 q = container_of(work, struct request_queue, delay_work.work);
186 spin_lock_irq(q->queue_lock);
188 spin_unlock_irq(q->queue_lock);
192 * blk_delay_queue - restart queueing after defined interval
193 * @q: The &struct request_queue in question
194 * @msecs: Delay in msecs
197 * Sometimes queueing needs to be postponed for a little while, to allow
198 * resources to come back. This function will make sure that queueing is
199 * restarted around the specified time. Queue lock must be held.
201 void blk_delay_queue(struct request_queue *q, unsigned long msecs)
203 if (likely(!blk_queue_dead(q)))
204 queue_delayed_work(kblockd_workqueue, &q->delay_work,
205 msecs_to_jiffies(msecs));
207 EXPORT_SYMBOL(blk_delay_queue);
210 * blk_start_queue - restart a previously stopped queue
211 * @q: The &struct request_queue in question
214 * blk_start_queue() will clear the stop flag on the queue, and call
215 * the request_fn for the queue if it was in a stopped state when
216 * entered. Also see blk_stop_queue(). Queue lock must be held.
218 void blk_start_queue(struct request_queue *q)
220 WARN_ON(!irqs_disabled());
222 queue_flag_clear(QUEUE_FLAG_STOPPED, q);
225 EXPORT_SYMBOL(blk_start_queue);
228 * blk_stop_queue - stop a queue
229 * @q: The &struct request_queue in question
232 * The Linux block layer assumes that a block driver will consume all
233 * entries on the request queue when the request_fn strategy is called.
234 * Often this will not happen, because of hardware limitations (queue
235 * depth settings). If a device driver gets a 'queue full' response,
236 * or if it simply chooses not to queue more I/O at one point, it can
237 * call this function to prevent the request_fn from being called until
238 * the driver has signalled it's ready to go again. This happens by calling
239 * blk_start_queue() to restart queue operations. Queue lock must be held.
241 void blk_stop_queue(struct request_queue *q)
243 cancel_delayed_work(&q->delay_work);
244 queue_flag_set(QUEUE_FLAG_STOPPED, q);
246 EXPORT_SYMBOL(blk_stop_queue);
249 * blk_sync_queue - cancel any pending callbacks on a queue
253 * The block layer may perform asynchronous callback activity
254 * on a queue, such as calling the unplug function after a timeout.
255 * A block device may call blk_sync_queue to ensure that any
256 * such activity is cancelled, thus allowing it to release resources
257 * that the callbacks might use. The caller must already have made sure
258 * that its ->make_request_fn will not re-add plugging prior to calling
261 * This function does not cancel any asynchronous activity arising
262 * out of elevator or throttling code. That would require elevator_exit()
263 * and blkcg_exit_queue() to be called with queue lock initialized.
266 void blk_sync_queue(struct request_queue *q)
268 del_timer_sync(&q->timeout);
271 struct blk_mq_hw_ctx *hctx;
274 queue_for_each_hw_ctx(q, hctx, i) {
275 cancel_delayed_work_sync(&hctx->run_work);
276 cancel_delayed_work_sync(&hctx->delay_work);
279 cancel_delayed_work_sync(&q->delay_work);
282 EXPORT_SYMBOL(blk_sync_queue);
285 * __blk_run_queue_uncond - run a queue whether or not it has been stopped
286 * @q: The queue to run
289 * Invoke request handling on a queue if there are any pending requests.
290 * May be used to restart request handling after a request has completed.
291 * This variant runs the queue whether or not the queue has been
292 * stopped. Must be called with the queue lock held and interrupts
293 * disabled. See also @blk_run_queue.
295 inline void __blk_run_queue_uncond(struct request_queue *q)
297 if (unlikely(blk_queue_dead(q)))
301 * Some request_fn implementations, e.g. scsi_request_fn(), unlock
302 * the queue lock internally. As a result multiple threads may be
303 * running such a request function concurrently. Keep track of the
304 * number of active request_fn invocations such that blk_drain_queue()
305 * can wait until all these request_fn calls have finished.
307 q->request_fn_active++;
309 q->request_fn_active--;
311 EXPORT_SYMBOL_GPL(__blk_run_queue_uncond);
314 * __blk_run_queue - run a single device queue
315 * @q: The queue to run
318 * See @blk_run_queue. This variant must be called with the queue lock
319 * held and interrupts disabled.
321 void __blk_run_queue(struct request_queue *q)
323 if (unlikely(blk_queue_stopped(q)))
326 __blk_run_queue_uncond(q);
328 EXPORT_SYMBOL(__blk_run_queue);
331 * blk_run_queue_async - run a single device queue in workqueue context
332 * @q: The queue to run
335 * Tells kblockd to perform the equivalent of @blk_run_queue on behalf
336 * of us. The caller must hold the queue lock.
338 void blk_run_queue_async(struct request_queue *q)
340 if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q)))
341 mod_delayed_work(kblockd_workqueue, &q->delay_work, 0);
343 EXPORT_SYMBOL(blk_run_queue_async);
346 * blk_run_queue - run a single device queue
347 * @q: The queue to run
350 * Invoke request handling on this queue, if it has pending work to do.
351 * May be used to restart queueing when a request has completed.
353 void blk_run_queue(struct request_queue *q)
357 spin_lock_irqsave(q->queue_lock, flags);
359 spin_unlock_irqrestore(q->queue_lock, flags);
361 EXPORT_SYMBOL(blk_run_queue);
363 void blk_put_queue(struct request_queue *q)
365 kobject_put(&q->kobj);
367 EXPORT_SYMBOL(blk_put_queue);
370 * __blk_drain_queue - drain requests from request_queue
372 * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
374 * Drain requests from @q. If @drain_all is set, all requests are drained.
375 * If not, only ELVPRIV requests are drained. The caller is responsible
376 * for ensuring that no new requests which need to be drained are queued.
378 static void __blk_drain_queue(struct request_queue *q, bool drain_all)
379 __releases(q->queue_lock)
380 __acquires(q->queue_lock)
384 lockdep_assert_held(q->queue_lock);
390 * The caller might be trying to drain @q before its
391 * elevator is initialized.
394 elv_drain_elevator(q);
396 blkcg_drain_queue(q);
399 * This function might be called on a queue which failed
400 * driver init after queue creation or is not yet fully
401 * active yet. Some drivers (e.g. fd and loop) get unhappy
402 * in such cases. Kick queue iff dispatch queue has
403 * something on it and @q has request_fn set.
405 if (!list_empty(&q->queue_head) && q->request_fn)
408 drain |= q->nr_rqs_elvpriv;
409 drain |= q->request_fn_active;
412 * Unfortunately, requests are queued at and tracked from
413 * multiple places and there's no single counter which can
414 * be drained. Check all the queues and counters.
417 struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
418 drain |= !list_empty(&q->queue_head);
419 for (i = 0; i < 2; i++) {
420 drain |= q->nr_rqs[i];
421 drain |= q->in_flight[i];
423 drain |= !list_empty(&fq->flush_queue[i]);
430 spin_unlock_irq(q->queue_lock);
434 spin_lock_irq(q->queue_lock);
438 * With queue marked dead, any woken up waiter will fail the
439 * allocation path, so the wakeup chaining is lost and we're
440 * left with hung waiters. We need to wake up those waiters.
443 struct request_list *rl;
445 blk_queue_for_each_rl(rl, q)
446 for (i = 0; i < ARRAY_SIZE(rl->wait); i++)
447 wake_up_all(&rl->wait[i]);
452 * blk_queue_bypass_start - enter queue bypass mode
453 * @q: queue of interest
455 * In bypass mode, only the dispatch FIFO queue of @q is used. This
456 * function makes @q enter bypass mode and drains all requests which were
457 * throttled or issued before. On return, it's guaranteed that no request
458 * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
459 * inside queue or RCU read lock.
461 void blk_queue_bypass_start(struct request_queue *q)
463 spin_lock_irq(q->queue_lock);
465 queue_flag_set(QUEUE_FLAG_BYPASS, q);
466 spin_unlock_irq(q->queue_lock);
469 * Queues start drained. Skip actual draining till init is
470 * complete. This avoids lenghty delays during queue init which
471 * can happen many times during boot.
473 if (blk_queue_init_done(q)) {
474 spin_lock_irq(q->queue_lock);
475 __blk_drain_queue(q, false);
476 spin_unlock_irq(q->queue_lock);
478 /* ensure blk_queue_bypass() is %true inside RCU read lock */
482 EXPORT_SYMBOL_GPL(blk_queue_bypass_start);
485 * blk_queue_bypass_end - leave queue bypass mode
486 * @q: queue of interest
488 * Leave bypass mode and restore the normal queueing behavior.
490 void blk_queue_bypass_end(struct request_queue *q)
492 spin_lock_irq(q->queue_lock);
493 if (!--q->bypass_depth)
494 queue_flag_clear(QUEUE_FLAG_BYPASS, q);
495 WARN_ON_ONCE(q->bypass_depth < 0);
496 spin_unlock_irq(q->queue_lock);
498 EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
500 void blk_set_queue_dying(struct request_queue *q)
502 queue_flag_set_unlocked(QUEUE_FLAG_DYING, q);
505 blk_mq_wake_waiters(q);
507 struct request_list *rl;
509 blk_queue_for_each_rl(rl, q) {
511 wake_up(&rl->wait[BLK_RW_SYNC]);
512 wake_up(&rl->wait[BLK_RW_ASYNC]);
517 EXPORT_SYMBOL_GPL(blk_set_queue_dying);
520 * blk_cleanup_queue - shutdown a request queue
521 * @q: request queue to shutdown
523 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
524 * put it. All future requests will be failed immediately with -ENODEV.
526 void blk_cleanup_queue(struct request_queue *q)
528 spinlock_t *lock = q->queue_lock;
530 /* mark @q DYING, no new request or merges will be allowed afterwards */
531 mutex_lock(&q->sysfs_lock);
532 blk_set_queue_dying(q);
536 * A dying queue is permanently in bypass mode till released. Note
537 * that, unlike blk_queue_bypass_start(), we aren't performing
538 * synchronize_rcu() after entering bypass mode to avoid the delay
539 * as some drivers create and destroy a lot of queues while
540 * probing. This is still safe because blk_release_queue() will be
541 * called only after the queue refcnt drops to zero and nothing,
542 * RCU or not, would be traversing the queue by then.
545 queue_flag_set(QUEUE_FLAG_BYPASS, q);
547 queue_flag_set(QUEUE_FLAG_NOMERGES, q);
548 queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
549 queue_flag_set(QUEUE_FLAG_DYING, q);
550 spin_unlock_irq(lock);
551 mutex_unlock(&q->sysfs_lock);
554 * Drain all requests queued before DYING marking. Set DEAD flag to
555 * prevent that q->request_fn() gets invoked after draining finished.
560 __blk_drain_queue(q, true);
561 queue_flag_set(QUEUE_FLAG_DEAD, q);
562 spin_unlock_irq(lock);
564 /* for synchronous bio-based driver finish in-flight integrity i/o */
565 blk_flush_integrity();
567 /* @q won't process any more request, flush async actions */
568 del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
572 blk_mq_free_queue(q);
573 percpu_ref_exit(&q->q_usage_counter);
576 if (q->queue_lock != &q->__queue_lock)
577 q->queue_lock = &q->__queue_lock;
578 spin_unlock_irq(lock);
580 bdi_unregister(&q->backing_dev_info);
582 /* @q is and will stay empty, shutdown and put */
585 EXPORT_SYMBOL(blk_cleanup_queue);
587 /* Allocate memory local to the request queue */
588 static void *alloc_request_struct(gfp_t gfp_mask, void *data)
590 int nid = (int)(long)data;
591 return kmem_cache_alloc_node(request_cachep, gfp_mask, nid);
594 static void free_request_struct(void *element, void *unused)
596 kmem_cache_free(request_cachep, element);
599 int blk_init_rl(struct request_list *rl, struct request_queue *q,
602 if (unlikely(rl->rq_pool))
606 rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
607 rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
608 init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
609 init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
611 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, alloc_request_struct,
613 (void *)(long)q->node, gfp_mask,
621 void blk_exit_rl(struct request_list *rl)
624 mempool_destroy(rl->rq_pool);
627 struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
629 return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE);
631 EXPORT_SYMBOL(blk_alloc_queue);
633 int blk_queue_enter(struct request_queue *q, gfp_t gfp)
638 if (percpu_ref_tryget_live(&q->q_usage_counter))
641 if (!(gfp & __GFP_WAIT))
644 ret = wait_event_interruptible(q->mq_freeze_wq,
645 !atomic_read(&q->mq_freeze_depth) ||
647 if (blk_queue_dying(q))
654 void blk_queue_exit(struct request_queue *q)
656 percpu_ref_put(&q->q_usage_counter);
659 static void blk_queue_usage_counter_release(struct percpu_ref *ref)
661 struct request_queue *q =
662 container_of(ref, struct request_queue, q_usage_counter);
664 wake_up_all(&q->mq_freeze_wq);
667 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
669 struct request_queue *q;
672 q = kmem_cache_alloc_node(blk_requestq_cachep,
673 gfp_mask | __GFP_ZERO, node_id);
677 q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask);
681 q->bio_split = bioset_create(BIO_POOL_SIZE, 0);
685 q->backing_dev_info.ra_pages =
686 (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
687 q->backing_dev_info.capabilities = BDI_CAP_CGROUP_WRITEBACK;
688 q->backing_dev_info.name = "block";
691 err = bdi_init(&q->backing_dev_info);
695 setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
696 laptop_mode_timer_fn, (unsigned long) q);
697 setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
698 INIT_LIST_HEAD(&q->queue_head);
699 INIT_LIST_HEAD(&q->timeout_list);
700 INIT_LIST_HEAD(&q->icq_list);
701 #ifdef CONFIG_BLK_CGROUP
702 INIT_LIST_HEAD(&q->blkg_list);
704 INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);
706 kobject_init(&q->kobj, &blk_queue_ktype);
708 mutex_init(&q->sysfs_lock);
709 spin_lock_init(&q->__queue_lock);
712 * By default initialize queue_lock to internal lock and driver can
713 * override it later if need be.
715 q->queue_lock = &q->__queue_lock;
718 * A queue starts its life with bypass turned on to avoid
719 * unnecessary bypass on/off overhead and nasty surprises during
720 * init. The initial bypass will be finished when the queue is
721 * registered by blk_register_queue().
724 __set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags);
726 init_waitqueue_head(&q->mq_freeze_wq);
729 * Init percpu_ref in atomic mode so that it's faster to shutdown.
730 * See blk_register_queue() for details.
732 if (percpu_ref_init(&q->q_usage_counter,
733 blk_queue_usage_counter_release,
734 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
737 if (blkcg_init_queue(q))
743 percpu_ref_exit(&q->q_usage_counter);
745 bdi_destroy(&q->backing_dev_info);
747 bioset_free(q->bio_split);
749 ida_simple_remove(&blk_queue_ida, q->id);
751 kmem_cache_free(blk_requestq_cachep, q);
754 EXPORT_SYMBOL(blk_alloc_queue_node);
757 * blk_init_queue - prepare a request queue for use with a block device
758 * @rfn: The function to be called to process requests that have been
759 * placed on the queue.
760 * @lock: Request queue spin lock
763 * If a block device wishes to use the standard request handling procedures,
764 * which sorts requests and coalesces adjacent requests, then it must
765 * call blk_init_queue(). The function @rfn will be called when there
766 * are requests on the queue that need to be processed. If the device
767 * supports plugging, then @rfn may not be called immediately when requests
768 * are available on the queue, but may be called at some time later instead.
769 * Plugged queues are generally unplugged when a buffer belonging to one
770 * of the requests on the queue is needed, or due to memory pressure.
772 * @rfn is not required, or even expected, to remove all requests off the
773 * queue, but only as many as it can handle at a time. If it does leave
774 * requests on the queue, it is responsible for arranging that the requests
775 * get dealt with eventually.
777 * The queue spin lock must be held while manipulating the requests on the
778 * request queue; this lock will be taken also from interrupt context, so irq
779 * disabling is needed for it.
781 * Function returns a pointer to the initialized request queue, or %NULL if
785 * blk_init_queue() must be paired with a blk_cleanup_queue() call
786 * when the block device is deactivated (such as at module unload).
789 struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
791 return blk_init_queue_node(rfn, lock, NUMA_NO_NODE);
793 EXPORT_SYMBOL(blk_init_queue);
795 struct request_queue *
796 blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
798 struct request_queue *uninit_q, *q;
800 uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id);
804 q = blk_init_allocated_queue(uninit_q, rfn, lock);
806 blk_cleanup_queue(uninit_q);
810 EXPORT_SYMBOL(blk_init_queue_node);
812 static void blk_queue_bio(struct request_queue *q, struct bio *bio);
814 struct request_queue *
815 blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
821 q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, 0);
825 if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))
829 q->prep_rq_fn = NULL;
830 q->unprep_rq_fn = NULL;
831 q->queue_flags |= QUEUE_FLAG_DEFAULT;
833 /* Override internal queue lock with supplied lock pointer */
835 q->queue_lock = lock;
838 * This also sets hw/phys segments, boundary and size
840 blk_queue_make_request(q, blk_queue_bio);
842 q->sg_reserved_size = INT_MAX;
844 /* Protect q->elevator from elevator_change */
845 mutex_lock(&q->sysfs_lock);
848 if (elevator_init(q, NULL)) {
849 mutex_unlock(&q->sysfs_lock);
853 mutex_unlock(&q->sysfs_lock);
858 blk_free_flush_queue(q->fq);
861 EXPORT_SYMBOL(blk_init_allocated_queue);
863 bool blk_get_queue(struct request_queue *q)
865 if (likely(!blk_queue_dying(q))) {
872 EXPORT_SYMBOL(blk_get_queue);
874 static inline void blk_free_request(struct request_list *rl, struct request *rq)
876 if (rq->cmd_flags & REQ_ELVPRIV) {
877 elv_put_request(rl->q, rq);
879 put_io_context(rq->elv.icq->ioc);
882 mempool_free(rq, rl->rq_pool);
886 * ioc_batching returns true if the ioc is a valid batching request and
887 * should be given priority access to a request.
889 static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
895 * Make sure the process is able to allocate at least 1 request
896 * even if the batch times out, otherwise we could theoretically
899 return ioc->nr_batch_requests == q->nr_batching ||
900 (ioc->nr_batch_requests > 0
901 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
905 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
906 * will cause the process to be a "batcher" on all queues in the system. This
907 * is the behaviour we want though - once it gets a wakeup it should be given
910 static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
912 if (!ioc || ioc_batching(q, ioc))
915 ioc->nr_batch_requests = q->nr_batching;
916 ioc->last_waited = jiffies;
919 static void __freed_request(struct request_list *rl, int sync)
921 struct request_queue *q = rl->q;
923 if (rl->count[sync] < queue_congestion_off_threshold(q))
924 blk_clear_congested(rl, sync);
926 if (rl->count[sync] + 1 <= q->nr_requests) {
927 if (waitqueue_active(&rl->wait[sync]))
928 wake_up(&rl->wait[sync]);
930 blk_clear_rl_full(rl, sync);
935 * A request has just been released. Account for it, update the full and
936 * congestion status, wake up any waiters. Called under q->queue_lock.
938 static void freed_request(struct request_list *rl, unsigned int flags)
940 struct request_queue *q = rl->q;
941 int sync = rw_is_sync(flags);
945 if (flags & REQ_ELVPRIV)
948 __freed_request(rl, sync);
950 if (unlikely(rl->starved[sync ^ 1]))
951 __freed_request(rl, sync ^ 1);
954 int blk_update_nr_requests(struct request_queue *q, unsigned int nr)
956 struct request_list *rl;
957 int on_thresh, off_thresh;
959 spin_lock_irq(q->queue_lock);
961 blk_queue_congestion_threshold(q);
962 on_thresh = queue_congestion_on_threshold(q);
963 off_thresh = queue_congestion_off_threshold(q);
965 blk_queue_for_each_rl(rl, q) {
966 if (rl->count[BLK_RW_SYNC] >= on_thresh)
967 blk_set_congested(rl, BLK_RW_SYNC);
968 else if (rl->count[BLK_RW_SYNC] < off_thresh)
969 blk_clear_congested(rl, BLK_RW_SYNC);
971 if (rl->count[BLK_RW_ASYNC] >= on_thresh)
972 blk_set_congested(rl, BLK_RW_ASYNC);
973 else if (rl->count[BLK_RW_ASYNC] < off_thresh)
974 blk_clear_congested(rl, BLK_RW_ASYNC);
976 if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
977 blk_set_rl_full(rl, BLK_RW_SYNC);
979 blk_clear_rl_full(rl, BLK_RW_SYNC);
980 wake_up(&rl->wait[BLK_RW_SYNC]);
983 if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
984 blk_set_rl_full(rl, BLK_RW_ASYNC);
986 blk_clear_rl_full(rl, BLK_RW_ASYNC);
987 wake_up(&rl->wait[BLK_RW_ASYNC]);
991 spin_unlock_irq(q->queue_lock);
996 * Determine if elevator data should be initialized when allocating the
997 * request associated with @bio.
999 static bool blk_rq_should_init_elevator(struct bio *bio)
1005 * Flush requests do not use the elevator so skip initialization.
1006 * This allows a request to share the flush and elevator data.
1008 if (bio->bi_rw & (REQ_FLUSH | REQ_FUA))
1015 * rq_ioc - determine io_context for request allocation
1016 * @bio: request being allocated is for this bio (can be %NULL)
1018 * Determine io_context to use for request allocation for @bio. May return
1019 * %NULL if %current->io_context doesn't exist.
1021 static struct io_context *rq_ioc(struct bio *bio)
1023 #ifdef CONFIG_BLK_CGROUP
1024 if (bio && bio->bi_ioc)
1027 return current->io_context;
1031 * __get_request - get a free request
1032 * @rl: request list to allocate from
1033 * @rw_flags: RW and SYNC flags
1034 * @bio: bio to allocate request for (can be %NULL)
1035 * @gfp_mask: allocation mask
1037 * Get a free request from @q. This function may fail under memory
1038 * pressure or if @q is dead.
1040 * Must be called with @q->queue_lock held and,
1041 * Returns ERR_PTR on failure, with @q->queue_lock held.
1042 * Returns request pointer on success, with @q->queue_lock *not held*.
1044 static struct request *__get_request(struct request_list *rl, int rw_flags,
1045 struct bio *bio, gfp_t gfp_mask)
1047 struct request_queue *q = rl->q;
1049 struct elevator_type *et = q->elevator->type;
1050 struct io_context *ioc = rq_ioc(bio);
1051 struct io_cq *icq = NULL;
1052 const bool is_sync = rw_is_sync(rw_flags) != 0;
1055 if (unlikely(blk_queue_dying(q)))
1056 return ERR_PTR(-ENODEV);
1058 may_queue = elv_may_queue(q, rw_flags);
1059 if (may_queue == ELV_MQUEUE_NO)
1062 if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
1063 if (rl->count[is_sync]+1 >= q->nr_requests) {
1065 * The queue will fill after this allocation, so set
1066 * it as full, and mark this process as "batching".
1067 * This process will be allowed to complete a batch of
1068 * requests, others will be blocked.
1070 if (!blk_rl_full(rl, is_sync)) {
1071 ioc_set_batching(q, ioc);
1072 blk_set_rl_full(rl, is_sync);
1074 if (may_queue != ELV_MQUEUE_MUST
1075 && !ioc_batching(q, ioc)) {
1077 * The queue is full and the allocating
1078 * process is not a "batcher", and not
1079 * exempted by the IO scheduler
1081 return ERR_PTR(-ENOMEM);
1085 blk_set_congested(rl, is_sync);
1089 * Only allow batching queuers to allocate up to 50% over the defined
1090 * limit of requests, otherwise we could have thousands of requests
1091 * allocated with any setting of ->nr_requests
1093 if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
1094 return ERR_PTR(-ENOMEM);
1096 q->nr_rqs[is_sync]++;
1097 rl->count[is_sync]++;
1098 rl->starved[is_sync] = 0;
1101 * Decide whether the new request will be managed by elevator. If
1102 * so, mark @rw_flags and increment elvpriv. Non-zero elvpriv will
1103 * prevent the current elevator from being destroyed until the new
1104 * request is freed. This guarantees icq's won't be destroyed and
1105 * makes creating new ones safe.
1107 * Also, lookup icq while holding queue_lock. If it doesn't exist,
1108 * it will be created after releasing queue_lock.
1110 if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) {
1111 rw_flags |= REQ_ELVPRIV;
1112 q->nr_rqs_elvpriv++;
1113 if (et->icq_cache && ioc)
1114 icq = ioc_lookup_icq(ioc, q);
1117 if (blk_queue_io_stat(q))
1118 rw_flags |= REQ_IO_STAT;
1119 spin_unlock_irq(q->queue_lock);
1121 /* allocate and init request */
1122 rq = mempool_alloc(rl->rq_pool, gfp_mask);
1127 blk_rq_set_rl(rq, rl);
1128 rq->cmd_flags = rw_flags | REQ_ALLOCED;
1131 if (rw_flags & REQ_ELVPRIV) {
1132 if (unlikely(et->icq_cache && !icq)) {
1134 icq = ioc_create_icq(ioc, q, gfp_mask);
1140 if (unlikely(elv_set_request(q, rq, bio, gfp_mask)))
1143 /* @rq->elv.icq holds io_context until @rq is freed */
1145 get_io_context(icq->ioc);
1149 * ioc may be NULL here, and ioc_batching will be false. That's
1150 * OK, if the queue is under the request limit then requests need
1151 * not count toward the nr_batch_requests limit. There will always
1152 * be some limit enforced by BLK_BATCH_TIME.
1154 if (ioc_batching(q, ioc))
1155 ioc->nr_batch_requests--;
1157 trace_block_getrq(q, bio, rw_flags & 1);
1162 * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed
1163 * and may fail indefinitely under memory pressure and thus
1164 * shouldn't stall IO. Treat this request as !elvpriv. This will
1165 * disturb iosched and blkcg but weird is bettern than dead.
1167 printk_ratelimited(KERN_WARNING "%s: dev %s: request aux data allocation failed, iosched may be disturbed\n",
1168 __func__, dev_name(q->backing_dev_info.dev));
1170 rq->cmd_flags &= ~REQ_ELVPRIV;
1173 spin_lock_irq(q->queue_lock);
1174 q->nr_rqs_elvpriv--;
1175 spin_unlock_irq(q->queue_lock);
1180 * Allocation failed presumably due to memory. Undo anything we
1181 * might have messed up.
1183 * Allocating task should really be put onto the front of the wait
1184 * queue, but this is pretty rare.
1186 spin_lock_irq(q->queue_lock);
1187 freed_request(rl, rw_flags);
1190 * in the very unlikely event that allocation failed and no
1191 * requests for this direction was pending, mark us starved so that
1192 * freeing of a request in the other direction will notice
1193 * us. another possible fix would be to split the rq mempool into
1197 if (unlikely(rl->count[is_sync] == 0))
1198 rl->starved[is_sync] = 1;
1199 return ERR_PTR(-ENOMEM);
1203 * get_request - get a free request
1204 * @q: request_queue to allocate request from
1205 * @rw_flags: RW and SYNC flags
1206 * @bio: bio to allocate request for (can be %NULL)
1207 * @gfp_mask: allocation mask
1209 * Get a free request from @q. If %__GFP_WAIT is set in @gfp_mask, this
1210 * function keeps retrying under memory pressure and fails iff @q is dead.
1212 * Must be called with @q->queue_lock held and,
1213 * Returns ERR_PTR on failure, with @q->queue_lock held.
1214 * Returns request pointer on success, with @q->queue_lock *not held*.
1216 static struct request *get_request(struct request_queue *q, int rw_flags,
1217 struct bio *bio, gfp_t gfp_mask)
1219 const bool is_sync = rw_is_sync(rw_flags) != 0;
1221 struct request_list *rl;
1224 rl = blk_get_rl(q, bio); /* transferred to @rq on success */
1226 rq = __get_request(rl, rw_flags, bio, gfp_mask);
1230 if (!(gfp_mask & __GFP_WAIT) || unlikely(blk_queue_dying(q))) {
1235 /* wait on @rl and retry */
1236 prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
1237 TASK_UNINTERRUPTIBLE);
1239 trace_block_sleeprq(q, bio, rw_flags & 1);
1241 spin_unlock_irq(q->queue_lock);
1245 * After sleeping, we become a "batching" process and will be able
1246 * to allocate at least one request, and up to a big batch of them
1247 * for a small period time. See ioc_batching, ioc_set_batching
1249 ioc_set_batching(q, current->io_context);
1251 spin_lock_irq(q->queue_lock);
1252 finish_wait(&rl->wait[is_sync], &wait);
1257 static struct request *blk_old_get_request(struct request_queue *q, int rw,
1262 BUG_ON(rw != READ && rw != WRITE);
1264 /* create ioc upfront */
1265 create_io_context(gfp_mask, q->node);
1267 spin_lock_irq(q->queue_lock);
1268 rq = get_request(q, rw, NULL, gfp_mask);
1270 spin_unlock_irq(q->queue_lock);
1271 /* q->queue_lock is unlocked at this point */
1276 struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
1279 return blk_mq_alloc_request(q, rw, gfp_mask, false);
1281 return blk_old_get_request(q, rw, gfp_mask);
1283 EXPORT_SYMBOL(blk_get_request);
1286 * blk_make_request - given a bio, allocate a corresponding struct request.
1287 * @q: target request queue
1288 * @bio: The bio describing the memory mappings that will be submitted for IO.
1289 * It may be a chained-bio properly constructed by block/bio layer.
1290 * @gfp_mask: gfp flags to be used for memory allocation
1292 * blk_make_request is the parallel of generic_make_request for BLOCK_PC
1293 * type commands. Where the struct request needs to be farther initialized by
1294 * the caller. It is passed a &struct bio, which describes the memory info of
1297 * The caller of blk_make_request must make sure that bi_io_vec
1298 * are set to describe the memory buffers. That bio_data_dir() will return
1299 * the needed direction of the request. (And all bio's in the passed bio-chain
1300 * are properly set accordingly)
1302 * If called under none-sleepable conditions, mapped bio buffers must not
1303 * need bouncing, by calling the appropriate masked or flagged allocator,
1304 * suitable for the target device. Otherwise the call to blk_queue_bounce will
1307 * WARNING: When allocating/cloning a bio-chain, careful consideration should be
1308 * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for
1309 * anything but the first bio in the chain. Otherwise you risk waiting for IO
1310 * completion of a bio that hasn't been submitted yet, thus resulting in a
1311 * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead
1312 * of bio_alloc(), as that avoids the mempool deadlock.
1313 * If possible a big IO should be split into smaller parts when allocation
1314 * fails. Partial allocation should not be an error, or you risk a live-lock.
1316 struct request *blk_make_request(struct request_queue *q, struct bio *bio,
1319 struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask);
1324 blk_rq_set_block_pc(rq);
1327 struct bio *bounce_bio = bio;
1330 blk_queue_bounce(q, &bounce_bio);
1331 ret = blk_rq_append_bio(q, rq, bounce_bio);
1332 if (unlikely(ret)) {
1333 blk_put_request(rq);
1334 return ERR_PTR(ret);
1340 EXPORT_SYMBOL(blk_make_request);
1343 * blk_rq_set_block_pc - initialize a request to type BLOCK_PC
1344 * @rq: request to be initialized
1347 void blk_rq_set_block_pc(struct request *rq)
1349 rq->cmd_type = REQ_TYPE_BLOCK_PC;
1351 rq->__sector = (sector_t) -1;
1352 rq->bio = rq->biotail = NULL;
1353 memset(rq->__cmd, 0, sizeof(rq->__cmd));
1355 EXPORT_SYMBOL(blk_rq_set_block_pc);
1358 * blk_requeue_request - put a request back on queue
1359 * @q: request queue where request should be inserted
1360 * @rq: request to be inserted
1363 * Drivers often keep queueing requests until the hardware cannot accept
1364 * more, when that condition happens we need to put the request back
1365 * on the queue. Must be called with queue lock held.
1367 void blk_requeue_request(struct request_queue *q, struct request *rq)
1369 blk_delete_timer(rq);
1370 blk_clear_rq_complete(rq);
1371 trace_block_rq_requeue(q, rq);
1373 if (rq->cmd_flags & REQ_QUEUED)
1374 blk_queue_end_tag(q, rq);
1376 BUG_ON(blk_queued_rq(rq));
1378 elv_requeue_request(q, rq);
1380 EXPORT_SYMBOL(blk_requeue_request);
1382 static void add_acct_request(struct request_queue *q, struct request *rq,
1385 blk_account_io_start(rq, true);
1386 __elv_add_request(q, rq, where);
1389 static void part_round_stats_single(int cpu, struct hd_struct *part,
1394 if (now == part->stamp)
1397 inflight = part_in_flight(part);
1399 __part_stat_add(cpu, part, time_in_queue,
1400 inflight * (now - part->stamp));
1401 __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
1407 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1408 * @cpu: cpu number for stats access
1409 * @part: target partition
1411 * The average IO queue length and utilisation statistics are maintained
1412 * by observing the current state of the queue length and the amount of
1413 * time it has been in this state for.
1415 * Normally, that accounting is done on IO completion, but that can result
1416 * in more than a second's worth of IO being accounted for within any one
1417 * second, leading to >100% utilisation. To deal with that, we call this
1418 * function to do a round-off before returning the results when reading
1419 * /proc/diskstats. This accounts immediately for all queue usage up to
1420 * the current jiffies and restarts the counters again.
1422 void part_round_stats(int cpu, struct hd_struct *part)
1424 unsigned long now = jiffies;
1427 part_round_stats_single(cpu, &part_to_disk(part)->part0, now);
1428 part_round_stats_single(cpu, part, now);
1430 EXPORT_SYMBOL_GPL(part_round_stats);
1433 static void blk_pm_put_request(struct request *rq)
1435 if (rq->q->dev && !(rq->cmd_flags & REQ_PM) && !--rq->q->nr_pending)
1436 pm_runtime_mark_last_busy(rq->q->dev);
1439 static inline void blk_pm_put_request(struct request *rq) {}
1443 * queue lock must be held
1445 void __blk_put_request(struct request_queue *q, struct request *req)
1451 blk_mq_free_request(req);
1455 blk_pm_put_request(req);
1457 elv_completed_request(q, req);
1459 /* this is a bio leak */
1460 WARN_ON(req->bio != NULL);
1463 * Request may not have originated from ll_rw_blk. if not,
1464 * it didn't come out of our reserved rq pools
1466 if (req->cmd_flags & REQ_ALLOCED) {
1467 unsigned int flags = req->cmd_flags;
1468 struct request_list *rl = blk_rq_rl(req);
1470 BUG_ON(!list_empty(&req->queuelist));
1471 BUG_ON(ELV_ON_HASH(req));
1473 blk_free_request(rl, req);
1474 freed_request(rl, flags);
1478 EXPORT_SYMBOL_GPL(__blk_put_request);
1480 void blk_put_request(struct request *req)
1482 struct request_queue *q = req->q;
1485 blk_mq_free_request(req);
1487 unsigned long flags;
1489 spin_lock_irqsave(q->queue_lock, flags);
1490 __blk_put_request(q, req);
1491 spin_unlock_irqrestore(q->queue_lock, flags);
1494 EXPORT_SYMBOL(blk_put_request);
1497 * blk_add_request_payload - add a payload to a request
1498 * @rq: request to update
1499 * @page: page backing the payload
1500 * @len: length of the payload.
1502 * This allows to later add a payload to an already submitted request by
1503 * a block driver. The driver needs to take care of freeing the payload
1506 * Note that this is a quite horrible hack and nothing but handling of
1507 * discard requests should ever use it.
1509 void blk_add_request_payload(struct request *rq, struct page *page,
1512 struct bio *bio = rq->bio;
1514 bio->bi_io_vec->bv_page = page;
1515 bio->bi_io_vec->bv_offset = 0;
1516 bio->bi_io_vec->bv_len = len;
1518 bio->bi_iter.bi_size = len;
1520 bio->bi_phys_segments = 1;
1522 rq->__data_len = rq->resid_len = len;
1523 rq->nr_phys_segments = 1;
1525 EXPORT_SYMBOL_GPL(blk_add_request_payload);
1527 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
1530 const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
1532 if (!ll_back_merge_fn(q, req, bio))
1535 trace_block_bio_backmerge(q, req, bio);
1537 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1538 blk_rq_set_mixed_merge(req);
1540 req->biotail->bi_next = bio;
1542 req->__data_len += bio->bi_iter.bi_size;
1543 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1545 blk_account_io_start(req, false);
1549 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
1552 const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
1554 if (!ll_front_merge_fn(q, req, bio))
1557 trace_block_bio_frontmerge(q, req, bio);
1559 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1560 blk_rq_set_mixed_merge(req);
1562 bio->bi_next = req->bio;
1565 req->__sector = bio->bi_iter.bi_sector;
1566 req->__data_len += bio->bi_iter.bi_size;
1567 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1569 blk_account_io_start(req, false);
1574 * blk_attempt_plug_merge - try to merge with %current's plugged list
1575 * @q: request_queue new bio is being queued at
1576 * @bio: new bio being queued
1577 * @request_count: out parameter for number of traversed plugged requests
1579 * Determine whether @bio being queued on @q can be merged with a request
1580 * on %current's plugged list. Returns %true if merge was successful,
1583 * Plugging coalesces IOs from the same issuer for the same purpose without
1584 * going through @q->queue_lock. As such it's more of an issuing mechanism
1585 * than scheduling, and the request, while may have elvpriv data, is not
1586 * added on the elevator at this point. In addition, we don't have
1587 * reliable access to the elevator outside queue lock. Only check basic
1588 * merging parameters without querying the elevator.
1590 * Caller must ensure !blk_queue_nomerges(q) beforehand.
1592 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
1593 unsigned int *request_count,
1594 struct request **same_queue_rq)
1596 struct blk_plug *plug;
1599 struct list_head *plug_list;
1601 plug = current->plug;
1607 plug_list = &plug->mq_list;
1609 plug_list = &plug->list;
1611 list_for_each_entry_reverse(rq, plug_list, queuelist) {
1617 * Only blk-mq multiple hardware queues case checks the
1618 * rq in the same queue, there should be only one such
1622 *same_queue_rq = rq;
1625 if (rq->q != q || !blk_rq_merge_ok(rq, bio))
1628 el_ret = blk_try_merge(rq, bio);
1629 if (el_ret == ELEVATOR_BACK_MERGE) {
1630 ret = bio_attempt_back_merge(q, rq, bio);
1633 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
1634 ret = bio_attempt_front_merge(q, rq, bio);
1643 unsigned int blk_plug_queued_count(struct request_queue *q)
1645 struct blk_plug *plug;
1647 struct list_head *plug_list;
1648 unsigned int ret = 0;
1650 plug = current->plug;
1655 plug_list = &plug->mq_list;
1657 plug_list = &plug->list;
1659 list_for_each_entry(rq, plug_list, queuelist) {
1667 void init_request_from_bio(struct request *req, struct bio *bio)
1669 req->cmd_type = REQ_TYPE_FS;
1671 req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK;
1672 if (bio->bi_rw & REQ_RAHEAD)
1673 req->cmd_flags |= REQ_FAILFAST_MASK;
1676 req->__sector = bio->bi_iter.bi_sector;
1677 req->ioprio = bio_prio(bio);
1678 blk_rq_bio_prep(req->q, req, bio);
1681 static void blk_queue_bio(struct request_queue *q, struct bio *bio)
1683 const bool sync = !!(bio->bi_rw & REQ_SYNC);
1684 struct blk_plug *plug;
1685 int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT;
1686 struct request *req;
1687 unsigned int request_count = 0;
1689 blk_queue_split(q, &bio, q->bio_split);
1692 * low level driver can indicate that it wants pages above a
1693 * certain limit bounced to low memory (ie for highmem, or even
1694 * ISA dma in theory)
1696 blk_queue_bounce(q, &bio);
1698 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1699 bio->bi_error = -EIO;
1704 if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
1705 spin_lock_irq(q->queue_lock);
1706 where = ELEVATOR_INSERT_FLUSH;
1711 * Check if we can merge with the plugged list before grabbing
1714 if (!blk_queue_nomerges(q)) {
1715 if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
1718 request_count = blk_plug_queued_count(q);
1720 spin_lock_irq(q->queue_lock);
1722 el_ret = elv_merge(q, &req, bio);
1723 if (el_ret == ELEVATOR_BACK_MERGE) {
1724 if (bio_attempt_back_merge(q, req, bio)) {
1725 elv_bio_merged(q, req, bio);
1726 if (!attempt_back_merge(q, req))
1727 elv_merged_request(q, req, el_ret);
1730 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
1731 if (bio_attempt_front_merge(q, req, bio)) {
1732 elv_bio_merged(q, req, bio);
1733 if (!attempt_front_merge(q, req))
1734 elv_merged_request(q, req, el_ret);
1741 * This sync check and mask will be re-done in init_request_from_bio(),
1742 * but we need to set it earlier to expose the sync flag to the
1743 * rq allocator and io schedulers.
1745 rw_flags = bio_data_dir(bio);
1747 rw_flags |= REQ_SYNC;
1750 * Grab a free request. This is might sleep but can not fail.
1751 * Returns with the queue unlocked.
1753 req = get_request(q, rw_flags, bio, GFP_NOIO);
1755 bio->bi_error = PTR_ERR(req);
1761 * After dropping the lock and possibly sleeping here, our request
1762 * may now be mergeable after it had proven unmergeable (above).
1763 * We don't worry about that case for efficiency. It won't happen
1764 * often, and the elevators are able to handle it.
1766 init_request_from_bio(req, bio);
1768 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags))
1769 req->cpu = raw_smp_processor_id();
1771 plug = current->plug;
1774 * If this is the first request added after a plug, fire
1778 trace_block_plug(q);
1780 if (request_count >= BLK_MAX_REQUEST_COUNT) {
1781 blk_flush_plug_list(plug, false);
1782 trace_block_plug(q);
1785 list_add_tail(&req->queuelist, &plug->list);
1786 blk_account_io_start(req, true);
1788 spin_lock_irq(q->queue_lock);
1789 add_acct_request(q, req, where);
1792 spin_unlock_irq(q->queue_lock);
1797 * If bio->bi_dev is a partition, remap the location
1799 static inline void blk_partition_remap(struct bio *bio)
1801 struct block_device *bdev = bio->bi_bdev;
1803 if (bio_sectors(bio) && bdev != bdev->bd_contains) {
1804 struct hd_struct *p = bdev->bd_part;
1806 bio->bi_iter.bi_sector += p->start_sect;
1807 bio->bi_bdev = bdev->bd_contains;
1809 trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio,
1811 bio->bi_iter.bi_sector - p->start_sect);
1815 static void handle_bad_sector(struct bio *bio)
1817 char b[BDEVNAME_SIZE];
1819 printk(KERN_INFO "attempt to access beyond end of device\n");
1820 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
1821 bdevname(bio->bi_bdev, b),
1823 (unsigned long long)bio_end_sector(bio),
1824 (long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9));
1827 #ifdef CONFIG_FAIL_MAKE_REQUEST
1829 static DECLARE_FAULT_ATTR(fail_make_request);
1831 static int __init setup_fail_make_request(char *str)
1833 return setup_fault_attr(&fail_make_request, str);
1835 __setup("fail_make_request=", setup_fail_make_request);
1837 static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
1839 return part->make_it_fail && should_fail(&fail_make_request, bytes);
1842 static int __init fail_make_request_debugfs(void)
1844 struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
1845 NULL, &fail_make_request);
1847 return PTR_ERR_OR_ZERO(dir);
1850 late_initcall(fail_make_request_debugfs);
1852 #else /* CONFIG_FAIL_MAKE_REQUEST */
1854 static inline bool should_fail_request(struct hd_struct *part,
1860 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1863 * Check whether this bio extends beyond the end of the device.
1865 static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
1872 /* Test device or partition size, when known. */
1873 maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
1875 sector_t sector = bio->bi_iter.bi_sector;
1877 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
1879 * This may well happen - the kernel calls bread()
1880 * without checking the size of the device, e.g., when
1881 * mounting a device.
1883 handle_bad_sector(bio);
1891 static noinline_for_stack bool
1892 generic_make_request_checks(struct bio *bio)
1894 struct request_queue *q;
1895 int nr_sectors = bio_sectors(bio);
1897 char b[BDEVNAME_SIZE];
1898 struct hd_struct *part;
1902 if (bio_check_eod(bio, nr_sectors))
1905 q = bdev_get_queue(bio->bi_bdev);
1908 "generic_make_request: Trying to access "
1909 "nonexistent block-device %s (%Lu)\n",
1910 bdevname(bio->bi_bdev, b),
1911 (long long) bio->bi_iter.bi_sector);
1915 part = bio->bi_bdev->bd_part;
1916 if (should_fail_request(part, bio->bi_iter.bi_size) ||
1917 should_fail_request(&part_to_disk(part)->part0,
1918 bio->bi_iter.bi_size))
1922 * If this device has partitions, remap block n
1923 * of partition p to block n+start(p) of the disk.
1925 blk_partition_remap(bio);
1927 if (bio_check_eod(bio, nr_sectors))
1931 * Filter flush bio's early so that make_request based
1932 * drivers without flush support don't have to worry
1935 if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) {
1936 bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA);
1943 if ((bio->bi_rw & REQ_DISCARD) &&
1944 (!blk_queue_discard(q) ||
1945 ((bio->bi_rw & REQ_SECURE) && !blk_queue_secdiscard(q)))) {
1950 if (bio->bi_rw & REQ_WRITE_SAME && !bdev_write_same(bio->bi_bdev)) {
1956 * Various block parts want %current->io_context and lazy ioc
1957 * allocation ends up trading a lot of pain for a small amount of
1958 * memory. Just allocate it upfront. This may fail and block
1959 * layer knows how to live with it.
1961 create_io_context(GFP_ATOMIC, q->node);
1963 if (!blkcg_bio_issue_check(q, bio))
1966 trace_block_bio_queue(q, bio);
1970 bio->bi_error = err;
1976 * generic_make_request - hand a buffer to its device driver for I/O
1977 * @bio: The bio describing the location in memory and on the device.
1979 * generic_make_request() is used to make I/O requests of block
1980 * devices. It is passed a &struct bio, which describes the I/O that needs
1983 * generic_make_request() does not return any status. The
1984 * success/failure status of the request, along with notification of
1985 * completion, is delivered asynchronously through the bio->bi_end_io
1986 * function described (one day) else where.
1988 * The caller of generic_make_request must make sure that bi_io_vec
1989 * are set to describe the memory buffer, and that bi_dev and bi_sector are
1990 * set to describe the device address, and the
1991 * bi_end_io and optionally bi_private are set to describe how
1992 * completion notification should be signaled.
1994 * generic_make_request and the drivers it calls may use bi_next if this
1995 * bio happens to be merged with someone else, and may resubmit the bio to
1996 * a lower device by calling into generic_make_request recursively, which
1997 * means the bio should NOT be touched after the call to ->make_request_fn.
1999 void generic_make_request(struct bio *bio)
2001 struct bio_list bio_list_on_stack;
2003 if (!generic_make_request_checks(bio))
2007 * We only want one ->make_request_fn to be active at a time, else
2008 * stack usage with stacked devices could be a problem. So use
2009 * current->bio_list to keep a list of requests submited by a
2010 * make_request_fn function. current->bio_list is also used as a
2011 * flag to say if generic_make_request is currently active in this
2012 * task or not. If it is NULL, then no make_request is active. If
2013 * it is non-NULL, then a make_request is active, and new requests
2014 * should be added at the tail
2016 if (current->bio_list) {
2017 bio_list_add(current->bio_list, bio);
2021 /* following loop may be a bit non-obvious, and so deserves some
2023 * Before entering the loop, bio->bi_next is NULL (as all callers
2024 * ensure that) so we have a list with a single bio.
2025 * We pretend that we have just taken it off a longer list, so
2026 * we assign bio_list to a pointer to the bio_list_on_stack,
2027 * thus initialising the bio_list of new bios to be
2028 * added. ->make_request() may indeed add some more bios
2029 * through a recursive call to generic_make_request. If it
2030 * did, we find a non-NULL value in bio_list and re-enter the loop
2031 * from the top. In this case we really did just take the bio
2032 * of the top of the list (no pretending) and so remove it from
2033 * bio_list, and call into ->make_request() again.
2035 BUG_ON(bio->bi_next);
2036 bio_list_init(&bio_list_on_stack);
2037 current->bio_list = &bio_list_on_stack;
2039 struct request_queue *q = bdev_get_queue(bio->bi_bdev);
2041 if (likely(blk_queue_enter(q, __GFP_WAIT) == 0)) {
2043 q->make_request_fn(q, bio);
2047 bio = bio_list_pop(current->bio_list);
2049 struct bio *bio_next = bio_list_pop(current->bio_list);
2055 current->bio_list = NULL; /* deactivate */
2057 EXPORT_SYMBOL(generic_make_request);
2060 * submit_bio - submit a bio to the block device layer for I/O
2061 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
2062 * @bio: The &struct bio which describes the I/O
2064 * submit_bio() is very similar in purpose to generic_make_request(), and
2065 * uses that function to do most of the work. Both are fairly rough
2066 * interfaces; @bio must be presetup and ready for I/O.
2069 void submit_bio(int rw, struct bio *bio)
2074 * If it's a regular read/write or a barrier with data attached,
2075 * go through the normal accounting stuff before submission.
2077 if (bio_has_data(bio)) {
2080 if (unlikely(rw & REQ_WRITE_SAME))
2081 count = bdev_logical_block_size(bio->bi_bdev) >> 9;
2083 count = bio_sectors(bio);
2086 count_vm_events(PGPGOUT, count);
2088 task_io_account_read(bio->bi_iter.bi_size);
2089 count_vm_events(PGPGIN, count);
2092 if (unlikely(block_dump)) {
2093 char b[BDEVNAME_SIZE];
2094 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
2095 current->comm, task_pid_nr(current),
2096 (rw & WRITE) ? "WRITE" : "READ",
2097 (unsigned long long)bio->bi_iter.bi_sector,
2098 bdevname(bio->bi_bdev, b),
2103 generic_make_request(bio);
2105 EXPORT_SYMBOL(submit_bio);
2108 * blk_rq_check_limits - Helper function to check a request for the queue limit
2110 * @rq: the request being checked
2113 * @rq may have been made based on weaker limitations of upper-level queues
2114 * in request stacking drivers, and it may violate the limitation of @q.
2115 * Since the block layer and the underlying device driver trust @rq
2116 * after it is inserted to @q, it should be checked against @q before
2117 * the insertion using this generic function.
2119 * This function should also be useful for request stacking drivers
2120 * in some cases below, so export this function.
2121 * Request stacking drivers like request-based dm may change the queue
2122 * limits while requests are in the queue (e.g. dm's table swapping).
2123 * Such request stacking drivers should check those requests against
2124 * the new queue limits again when they dispatch those requests,
2125 * although such checkings are also done against the old queue limits
2126 * when submitting requests.
2128 int blk_rq_check_limits(struct request_queue *q, struct request *rq)
2130 if (!rq_mergeable(rq))
2133 if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, rq->cmd_flags)) {
2134 printk(KERN_ERR "%s: over max size limit.\n", __func__);
2139 * queue's settings related to segment counting like q->bounce_pfn
2140 * may differ from that of other stacking queues.
2141 * Recalculate it to check the request correctly on this queue's
2144 blk_recalc_rq_segments(rq);
2145 if (rq->nr_phys_segments > queue_max_segments(q)) {
2146 printk(KERN_ERR "%s: over max segments limit.\n", __func__);
2152 EXPORT_SYMBOL_GPL(blk_rq_check_limits);
2155 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
2156 * @q: the queue to submit the request
2157 * @rq: the request being queued
2159 int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
2161 unsigned long flags;
2162 int where = ELEVATOR_INSERT_BACK;
2164 if (blk_rq_check_limits(q, rq))
2168 should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
2172 if (blk_queue_io_stat(q))
2173 blk_account_io_start(rq, true);
2174 blk_mq_insert_request(rq, false, true, true);
2178 spin_lock_irqsave(q->queue_lock, flags);
2179 if (unlikely(blk_queue_dying(q))) {
2180 spin_unlock_irqrestore(q->queue_lock, flags);
2185 * Submitting request must be dequeued before calling this function
2186 * because it will be linked to another request_queue
2188 BUG_ON(blk_queued_rq(rq));
2190 if (rq->cmd_flags & (REQ_FLUSH|REQ_FUA))
2191 where = ELEVATOR_INSERT_FLUSH;
2193 add_acct_request(q, rq, where);
2194 if (where == ELEVATOR_INSERT_FLUSH)
2196 spin_unlock_irqrestore(q->queue_lock, flags);
2200 EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
2203 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
2204 * @rq: request to examine
2207 * A request could be merge of IOs which require different failure
2208 * handling. This function determines the number of bytes which
2209 * can be failed from the beginning of the request without
2210 * crossing into area which need to be retried further.
2213 * The number of bytes to fail.
2216 * queue_lock must be held.
2218 unsigned int blk_rq_err_bytes(const struct request *rq)
2220 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
2221 unsigned int bytes = 0;
2224 if (!(rq->cmd_flags & REQ_MIXED_MERGE))
2225 return blk_rq_bytes(rq);
2228 * Currently the only 'mixing' which can happen is between
2229 * different fastfail types. We can safely fail portions
2230 * which have all the failfast bits that the first one has -
2231 * the ones which are at least as eager to fail as the first
2234 for (bio = rq->bio; bio; bio = bio->bi_next) {
2235 if ((bio->bi_rw & ff) != ff)
2237 bytes += bio->bi_iter.bi_size;
2240 /* this could lead to infinite loop */
2241 BUG_ON(blk_rq_bytes(rq) && !bytes);
2244 EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
2246 void blk_account_io_completion(struct request *req, unsigned int bytes)
2248 if (blk_do_io_stat(req)) {
2249 const int rw = rq_data_dir(req);
2250 struct hd_struct *part;
2253 cpu = part_stat_lock();
2255 part_stat_add(cpu, part, sectors[rw], bytes >> 9);
2260 void blk_account_io_done(struct request *req)
2263 * Account IO completion. flush_rq isn't accounted as a
2264 * normal IO on queueing nor completion. Accounting the
2265 * containing request is enough.
2267 if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) {
2268 unsigned long duration = jiffies - req->start_time;
2269 const int rw = rq_data_dir(req);
2270 struct hd_struct *part;
2273 cpu = part_stat_lock();
2276 part_stat_inc(cpu, part, ios[rw]);
2277 part_stat_add(cpu, part, ticks[rw], duration);
2278 part_round_stats(cpu, part);
2279 part_dec_in_flight(part, rw);
2281 hd_struct_put(part);
2288 * Don't process normal requests when queue is suspended
2289 * or in the process of suspending/resuming
2291 static struct request *blk_pm_peek_request(struct request_queue *q,
2294 if (q->dev && (q->rpm_status == RPM_SUSPENDED ||
2295 (q->rpm_status != RPM_ACTIVE && !(rq->cmd_flags & REQ_PM))))
2301 static inline struct request *blk_pm_peek_request(struct request_queue *q,
2308 void blk_account_io_start(struct request *rq, bool new_io)
2310 struct hd_struct *part;
2311 int rw = rq_data_dir(rq);
2314 if (!blk_do_io_stat(rq))
2317 cpu = part_stat_lock();
2321 part_stat_inc(cpu, part, merges[rw]);
2323 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
2324 if (!hd_struct_try_get(part)) {
2326 * The partition is already being removed,
2327 * the request will be accounted on the disk only
2329 * We take a reference on disk->part0 although that
2330 * partition will never be deleted, so we can treat
2331 * it as any other partition.
2333 part = &rq->rq_disk->part0;
2334 hd_struct_get(part);
2336 part_round_stats(cpu, part);
2337 part_inc_in_flight(part, rw);
2345 * blk_peek_request - peek at the top of a request queue
2346 * @q: request queue to peek at
2349 * Return the request at the top of @q. The returned request
2350 * should be started using blk_start_request() before LLD starts
2354 * Pointer to the request at the top of @q if available. Null
2358 * queue_lock must be held.
2360 struct request *blk_peek_request(struct request_queue *q)
2365 while ((rq = __elv_next_request(q)) != NULL) {
2367 rq = blk_pm_peek_request(q, rq);
2371 if (!(rq->cmd_flags & REQ_STARTED)) {
2373 * This is the first time the device driver
2374 * sees this request (possibly after
2375 * requeueing). Notify IO scheduler.
2377 if (rq->cmd_flags & REQ_SORTED)
2378 elv_activate_rq(q, rq);
2381 * just mark as started even if we don't start
2382 * it, a request that has been delayed should
2383 * not be passed by new incoming requests
2385 rq->cmd_flags |= REQ_STARTED;
2386 trace_block_rq_issue(q, rq);
2389 if (!q->boundary_rq || q->boundary_rq == rq) {
2390 q->end_sector = rq_end_sector(rq);
2391 q->boundary_rq = NULL;
2394 if (rq->cmd_flags & REQ_DONTPREP)
2397 if (q->dma_drain_size && blk_rq_bytes(rq)) {
2399 * make sure space for the drain appears we
2400 * know we can do this because max_hw_segments
2401 * has been adjusted to be one fewer than the
2404 rq->nr_phys_segments++;
2410 ret = q->prep_rq_fn(q, rq);
2411 if (ret == BLKPREP_OK) {
2413 } else if (ret == BLKPREP_DEFER) {
2415 * the request may have been (partially) prepped.
2416 * we need to keep this request in the front to
2417 * avoid resource deadlock. REQ_STARTED will
2418 * prevent other fs requests from passing this one.
2420 if (q->dma_drain_size && blk_rq_bytes(rq) &&
2421 !(rq->cmd_flags & REQ_DONTPREP)) {
2423 * remove the space for the drain we added
2424 * so that we don't add it again
2426 --rq->nr_phys_segments;
2431 } else if (ret == BLKPREP_KILL) {
2432 rq->cmd_flags |= REQ_QUIET;
2434 * Mark this request as started so we don't trigger
2435 * any debug logic in the end I/O path.
2437 blk_start_request(rq);
2438 __blk_end_request_all(rq, -EIO);
2440 printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
2447 EXPORT_SYMBOL(blk_peek_request);
2449 void blk_dequeue_request(struct request *rq)
2451 struct request_queue *q = rq->q;
2453 BUG_ON(list_empty(&rq->queuelist));
2454 BUG_ON(ELV_ON_HASH(rq));
2456 list_del_init(&rq->queuelist);
2459 * the time frame between a request being removed from the lists
2460 * and to it is freed is accounted as io that is in progress at
2463 if (blk_account_rq(rq)) {
2464 q->in_flight[rq_is_sync(rq)]++;
2465 set_io_start_time_ns(rq);
2470 * blk_start_request - start request processing on the driver
2471 * @req: request to dequeue
2474 * Dequeue @req and start timeout timer on it. This hands off the
2475 * request to the driver.
2477 * Block internal functions which don't want to start timer should
2478 * call blk_dequeue_request().
2481 * queue_lock must be held.
2483 void blk_start_request(struct request *req)
2485 blk_dequeue_request(req);
2488 * We are now handing the request to the hardware, initialize
2489 * resid_len to full count and add the timeout handler.
2491 req->resid_len = blk_rq_bytes(req);
2492 if (unlikely(blk_bidi_rq(req)))
2493 req->next_rq->resid_len = blk_rq_bytes(req->next_rq);
2495 BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
2498 EXPORT_SYMBOL(blk_start_request);
2501 * blk_fetch_request - fetch a request from a request queue
2502 * @q: request queue to fetch a request from
2505 * Return the request at the top of @q. The request is started on
2506 * return and LLD can start processing it immediately.
2509 * Pointer to the request at the top of @q if available. Null
2513 * queue_lock must be held.
2515 struct request *blk_fetch_request(struct request_queue *q)
2519 rq = blk_peek_request(q);
2521 blk_start_request(rq);
2524 EXPORT_SYMBOL(blk_fetch_request);
2527 * blk_update_request - Special helper function for request stacking drivers
2528 * @req: the request being processed
2529 * @error: %0 for success, < %0 for error
2530 * @nr_bytes: number of bytes to complete @req
2533 * Ends I/O on a number of bytes attached to @req, but doesn't complete
2534 * the request structure even if @req doesn't have leftover.
2535 * If @req has leftover, sets it up for the next range of segments.
2537 * This special helper function is only for request stacking drivers
2538 * (e.g. request-based dm) so that they can handle partial completion.
2539 * Actual device drivers should use blk_end_request instead.
2541 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
2542 * %false return from this function.
2545 * %false - this request doesn't have any more data
2546 * %true - this request has more data
2548 bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
2552 trace_block_rq_complete(req->q, req, nr_bytes);
2558 * For fs requests, rq is just carrier of independent bio's
2559 * and each partial completion should be handled separately.
2560 * Reset per-request error on each partial completion.
2562 * TODO: tj: This is too subtle. It would be better to let
2563 * low level drivers do what they see fit.
2565 if (req->cmd_type == REQ_TYPE_FS)
2568 if (error && req->cmd_type == REQ_TYPE_FS &&
2569 !(req->cmd_flags & REQ_QUIET)) {
2574 error_type = "recoverable transport";
2577 error_type = "critical target";
2580 error_type = "critical nexus";
2583 error_type = "timeout";
2586 error_type = "critical space allocation";
2589 error_type = "critical medium";
2596 printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n",
2597 __func__, error_type, req->rq_disk ?
2598 req->rq_disk->disk_name : "?",
2599 (unsigned long long)blk_rq_pos(req));
2603 blk_account_io_completion(req, nr_bytes);
2607 struct bio *bio = req->bio;
2608 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);
2610 if (bio_bytes == bio->bi_iter.bi_size)
2611 req->bio = bio->bi_next;
2613 req_bio_endio(req, bio, bio_bytes, error);
2615 total_bytes += bio_bytes;
2616 nr_bytes -= bio_bytes;
2627 * Reset counters so that the request stacking driver
2628 * can find how many bytes remain in the request
2631 req->__data_len = 0;
2635 req->__data_len -= total_bytes;
2637 /* update sector only for requests with clear definition of sector */
2638 if (req->cmd_type == REQ_TYPE_FS)
2639 req->__sector += total_bytes >> 9;
2641 /* mixed attributes always follow the first bio */
2642 if (req->cmd_flags & REQ_MIXED_MERGE) {
2643 req->cmd_flags &= ~REQ_FAILFAST_MASK;
2644 req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK;
2648 * If total number of sectors is less than the first segment
2649 * size, something has gone terribly wrong.
2651 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
2652 blk_dump_rq_flags(req, "request botched");
2653 req->__data_len = blk_rq_cur_bytes(req);
2656 /* recalculate the number of segments */
2657 blk_recalc_rq_segments(req);
2661 EXPORT_SYMBOL_GPL(blk_update_request);
2663 static bool blk_update_bidi_request(struct request *rq, int error,
2664 unsigned int nr_bytes,
2665 unsigned int bidi_bytes)
2667 if (blk_update_request(rq, error, nr_bytes))
2670 /* Bidi request must be completed as a whole */
2671 if (unlikely(blk_bidi_rq(rq)) &&
2672 blk_update_request(rq->next_rq, error, bidi_bytes))
2675 if (blk_queue_add_random(rq->q))
2676 add_disk_randomness(rq->rq_disk);
2682 * blk_unprep_request - unprepare a request
2685 * This function makes a request ready for complete resubmission (or
2686 * completion). It happens only after all error handling is complete,
2687 * so represents the appropriate moment to deallocate any resources
2688 * that were allocated to the request in the prep_rq_fn. The queue
2689 * lock is held when calling this.
2691 void blk_unprep_request(struct request *req)
2693 struct request_queue *q = req->q;
2695 req->cmd_flags &= ~REQ_DONTPREP;
2696 if (q->unprep_rq_fn)
2697 q->unprep_rq_fn(q, req);
2699 EXPORT_SYMBOL_GPL(blk_unprep_request);
2702 * queue lock must be held
2704 void blk_finish_request(struct request *req, int error)
2706 if (req->cmd_flags & REQ_QUEUED)
2707 blk_queue_end_tag(req->q, req);
2709 BUG_ON(blk_queued_rq(req));
2711 if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS)
2712 laptop_io_completion(&req->q->backing_dev_info);
2714 blk_delete_timer(req);
2716 if (req->cmd_flags & REQ_DONTPREP)
2717 blk_unprep_request(req);
2719 blk_account_io_done(req);
2722 req->end_io(req, error);
2724 if (blk_bidi_rq(req))
2725 __blk_put_request(req->next_rq->q, req->next_rq);
2727 __blk_put_request(req->q, req);
2730 EXPORT_SYMBOL(blk_finish_request);
2733 * blk_end_bidi_request - Complete a bidi request
2734 * @rq: the request to complete
2735 * @error: %0 for success, < %0 for error
2736 * @nr_bytes: number of bytes to complete @rq
2737 * @bidi_bytes: number of bytes to complete @rq->next_rq
2740 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2741 * Drivers that supports bidi can safely call this member for any
2742 * type of request, bidi or uni. In the later case @bidi_bytes is
2746 * %false - we are done with this request
2747 * %true - still buffers pending for this request
2749 static bool blk_end_bidi_request(struct request *rq, int error,
2750 unsigned int nr_bytes, unsigned int bidi_bytes)
2752 struct request_queue *q = rq->q;
2753 unsigned long flags;
2755 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2758 spin_lock_irqsave(q->queue_lock, flags);
2759 blk_finish_request(rq, error);
2760 spin_unlock_irqrestore(q->queue_lock, flags);
2766 * __blk_end_bidi_request - Complete a bidi request with queue lock held
2767 * @rq: the request to complete
2768 * @error: %0 for success, < %0 for error
2769 * @nr_bytes: number of bytes to complete @rq
2770 * @bidi_bytes: number of bytes to complete @rq->next_rq
2773 * Identical to blk_end_bidi_request() except that queue lock is
2774 * assumed to be locked on entry and remains so on return.
2777 * %false - we are done with this request
2778 * %true - still buffers pending for this request
2780 bool __blk_end_bidi_request(struct request *rq, int error,
2781 unsigned int nr_bytes, unsigned int bidi_bytes)
2783 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2786 blk_finish_request(rq, error);
2792 * blk_end_request - Helper function for drivers to complete the request.
2793 * @rq: the request being processed
2794 * @error: %0 for success, < %0 for error
2795 * @nr_bytes: number of bytes to complete
2798 * Ends I/O on a number of bytes attached to @rq.
2799 * If @rq has leftover, sets it up for the next range of segments.
2802 * %false - we are done with this request
2803 * %true - still buffers pending for this request
2805 bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
2807 return blk_end_bidi_request(rq, error, nr_bytes, 0);
2809 EXPORT_SYMBOL(blk_end_request);
2812 * blk_end_request_all - Helper function for drives to finish the request.
2813 * @rq: the request to finish
2814 * @error: %0 for success, < %0 for error
2817 * Completely finish @rq.
2819 void blk_end_request_all(struct request *rq, int error)
2822 unsigned int bidi_bytes = 0;
2824 if (unlikely(blk_bidi_rq(rq)))
2825 bidi_bytes = blk_rq_bytes(rq->next_rq);
2827 pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2830 EXPORT_SYMBOL(blk_end_request_all);
2833 * blk_end_request_cur - Helper function to finish the current request chunk.
2834 * @rq: the request to finish the current chunk for
2835 * @error: %0 for success, < %0 for error
2838 * Complete the current consecutively mapped chunk from @rq.
2841 * %false - we are done with this request
2842 * %true - still buffers pending for this request
2844 bool blk_end_request_cur(struct request *rq, int error)
2846 return blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2848 EXPORT_SYMBOL(blk_end_request_cur);
2851 * blk_end_request_err - Finish a request till the next failure boundary.
2852 * @rq: the request to finish till the next failure boundary for
2853 * @error: must be negative errno
2856 * Complete @rq till the next failure boundary.
2859 * %false - we are done with this request
2860 * %true - still buffers pending for this request
2862 bool blk_end_request_err(struct request *rq, int error)
2864 WARN_ON(error >= 0);
2865 return blk_end_request(rq, error, blk_rq_err_bytes(rq));
2867 EXPORT_SYMBOL_GPL(blk_end_request_err);
2870 * __blk_end_request - Helper function for drivers to complete the request.
2871 * @rq: the request being processed
2872 * @error: %0 for success, < %0 for error
2873 * @nr_bytes: number of bytes to complete
2876 * Must be called with queue lock held unlike blk_end_request().
2879 * %false - we are done with this request
2880 * %true - still buffers pending for this request
2882 bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
2884 return __blk_end_bidi_request(rq, error, nr_bytes, 0);
2886 EXPORT_SYMBOL(__blk_end_request);
2889 * __blk_end_request_all - Helper function for drives to finish the request.
2890 * @rq: the request to finish
2891 * @error: %0 for success, < %0 for error
2894 * Completely finish @rq. Must be called with queue lock held.
2896 void __blk_end_request_all(struct request *rq, int error)
2899 unsigned int bidi_bytes = 0;
2901 if (unlikely(blk_bidi_rq(rq)))
2902 bidi_bytes = blk_rq_bytes(rq->next_rq);
2904 pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2907 EXPORT_SYMBOL(__blk_end_request_all);
2910 * __blk_end_request_cur - Helper function to finish the current request chunk.
2911 * @rq: the request to finish the current chunk for
2912 * @error: %0 for success, < %0 for error
2915 * Complete the current consecutively mapped chunk from @rq. Must
2916 * be called with queue lock held.
2919 * %false - we are done with this request
2920 * %true - still buffers pending for this request
2922 bool __blk_end_request_cur(struct request *rq, int error)
2924 return __blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2926 EXPORT_SYMBOL(__blk_end_request_cur);
2929 * __blk_end_request_err - Finish a request till the next failure boundary.
2930 * @rq: the request to finish till the next failure boundary for
2931 * @error: must be negative errno
2934 * Complete @rq till the next failure boundary. Must be called
2935 * with queue lock held.
2938 * %false - we are done with this request
2939 * %true - still buffers pending for this request
2941 bool __blk_end_request_err(struct request *rq, int error)
2943 WARN_ON(error >= 0);
2944 return __blk_end_request(rq, error, blk_rq_err_bytes(rq));
2946 EXPORT_SYMBOL_GPL(__blk_end_request_err);
2948 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
2951 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */
2952 rq->cmd_flags |= bio->bi_rw & REQ_WRITE;
2954 if (bio_has_data(bio))
2955 rq->nr_phys_segments = bio_phys_segments(q, bio);
2957 rq->__data_len = bio->bi_iter.bi_size;
2958 rq->bio = rq->biotail = bio;
2961 rq->rq_disk = bio->bi_bdev->bd_disk;
2964 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
2966 * rq_flush_dcache_pages - Helper function to flush all pages in a request
2967 * @rq: the request to be flushed
2970 * Flush all pages in @rq.
2972 void rq_flush_dcache_pages(struct request *rq)
2974 struct req_iterator iter;
2975 struct bio_vec bvec;
2977 rq_for_each_segment(bvec, rq, iter)
2978 flush_dcache_page(bvec.bv_page);
2980 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
2984 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
2985 * @q : the queue of the device being checked
2988 * Check if underlying low-level drivers of a device are busy.
2989 * If the drivers want to export their busy state, they must set own
2990 * exporting function using blk_queue_lld_busy() first.
2992 * Basically, this function is used only by request stacking drivers
2993 * to stop dispatching requests to underlying devices when underlying
2994 * devices are busy. This behavior helps more I/O merging on the queue
2995 * of the request stacking driver and prevents I/O throughput regression
2996 * on burst I/O load.
2999 * 0 - Not busy (The request stacking driver should dispatch request)
3000 * 1 - Busy (The request stacking driver should stop dispatching request)
3002 int blk_lld_busy(struct request_queue *q)
3005 return q->lld_busy_fn(q);
3009 EXPORT_SYMBOL_GPL(blk_lld_busy);
3012 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
3013 * @rq: the clone request to be cleaned up
3016 * Free all bios in @rq for a cloned request.
3018 void blk_rq_unprep_clone(struct request *rq)
3022 while ((bio = rq->bio) != NULL) {
3023 rq->bio = bio->bi_next;
3028 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
3031 * Copy attributes of the original request to the clone request.
3032 * The actual data parts (e.g. ->cmd, ->sense) are not copied.
3034 static void __blk_rq_prep_clone(struct request *dst, struct request *src)
3036 dst->cpu = src->cpu;
3037 dst->cmd_flags |= (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE;
3038 dst->cmd_type = src->cmd_type;
3039 dst->__sector = blk_rq_pos(src);
3040 dst->__data_len = blk_rq_bytes(src);
3041 dst->nr_phys_segments = src->nr_phys_segments;
3042 dst->ioprio = src->ioprio;
3043 dst->extra_len = src->extra_len;
3047 * blk_rq_prep_clone - Helper function to setup clone request
3048 * @rq: the request to be setup
3049 * @rq_src: original request to be cloned
3050 * @bs: bio_set that bios for clone are allocated from
3051 * @gfp_mask: memory allocation mask for bio
3052 * @bio_ctr: setup function to be called for each clone bio.
3053 * Returns %0 for success, non %0 for failure.
3054 * @data: private data to be passed to @bio_ctr
3057 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
3058 * The actual data parts of @rq_src (e.g. ->cmd, ->sense)
3059 * are not copied, and copying such parts is the caller's responsibility.
3060 * Also, pages which the original bios are pointing to are not copied
3061 * and the cloned bios just point same pages.
3062 * So cloned bios must be completed before original bios, which means
3063 * the caller must complete @rq before @rq_src.
3065 int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
3066 struct bio_set *bs, gfp_t gfp_mask,
3067 int (*bio_ctr)(struct bio *, struct bio *, void *),
3070 struct bio *bio, *bio_src;
3075 __rq_for_each_bio(bio_src, rq_src) {
3076 bio = bio_clone_fast(bio_src, gfp_mask, bs);
3080 if (bio_ctr && bio_ctr(bio, bio_src, data))
3084 rq->biotail->bi_next = bio;
3087 rq->bio = rq->biotail = bio;
3090 __blk_rq_prep_clone(rq, rq_src);
3097 blk_rq_unprep_clone(rq);
3101 EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
3103 int kblockd_schedule_work(struct work_struct *work)
3105 return queue_work(kblockd_workqueue, work);
3107 EXPORT_SYMBOL(kblockd_schedule_work);
3109 int kblockd_schedule_delayed_work(struct delayed_work *dwork,
3110 unsigned long delay)
3112 return queue_delayed_work(kblockd_workqueue, dwork, delay);
3114 EXPORT_SYMBOL(kblockd_schedule_delayed_work);
3116 int kblockd_schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
3117 unsigned long delay)
3119 return queue_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
3121 EXPORT_SYMBOL(kblockd_schedule_delayed_work_on);
3124 * blk_start_plug - initialize blk_plug and track it inside the task_struct
3125 * @plug: The &struct blk_plug that needs to be initialized
3128 * Tracking blk_plug inside the task_struct will help with auto-flushing the
3129 * pending I/O should the task end up blocking between blk_start_plug() and
3130 * blk_finish_plug(). This is important from a performance perspective, but
3131 * also ensures that we don't deadlock. For instance, if the task is blocking
3132 * for a memory allocation, memory reclaim could end up wanting to free a
3133 * page belonging to that request that is currently residing in our private
3134 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
3135 * this kind of deadlock.
3137 void blk_start_plug(struct blk_plug *plug)
3139 struct task_struct *tsk = current;
3142 * If this is a nested plug, don't actually assign it.
3147 INIT_LIST_HEAD(&plug->list);
3148 INIT_LIST_HEAD(&plug->mq_list);
3149 INIT_LIST_HEAD(&plug->cb_list);
3151 * Store ordering should not be needed here, since a potential
3152 * preempt will imply a full memory barrier
3156 EXPORT_SYMBOL(blk_start_plug);
3158 static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
3160 struct request *rqa = container_of(a, struct request, queuelist);
3161 struct request *rqb = container_of(b, struct request, queuelist);
3163 return !(rqa->q < rqb->q ||
3164 (rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb)));
3168 * If 'from_schedule' is true, then postpone the dispatch of requests
3169 * until a safe kblockd context. We due this to avoid accidental big
3170 * additional stack usage in driver dispatch, in places where the originally
3171 * plugger did not intend it.
3173 static void queue_unplugged(struct request_queue *q, unsigned int depth,
3175 __releases(q->queue_lock)
3177 trace_block_unplug(q, depth, !from_schedule);
3180 blk_run_queue_async(q);
3183 spin_unlock(q->queue_lock);
3186 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
3188 LIST_HEAD(callbacks);
3190 while (!list_empty(&plug->cb_list)) {
3191 list_splice_init(&plug->cb_list, &callbacks);
3193 while (!list_empty(&callbacks)) {
3194 struct blk_plug_cb *cb = list_first_entry(&callbacks,
3197 list_del(&cb->list);
3198 cb->callback(cb, from_schedule);
3203 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
3206 struct blk_plug *plug = current->plug;
3207 struct blk_plug_cb *cb;
3212 list_for_each_entry(cb, &plug->cb_list, list)
3213 if (cb->callback == unplug && cb->data == data)
3216 /* Not currently on the callback list */
3217 BUG_ON(size < sizeof(*cb));
3218 cb = kzalloc(size, GFP_ATOMIC);
3221 cb->callback = unplug;
3222 list_add(&cb->list, &plug->cb_list);
3226 EXPORT_SYMBOL(blk_check_plugged);
3228 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
3230 struct request_queue *q;
3231 unsigned long flags;
3236 flush_plug_callbacks(plug, from_schedule);
3238 if (!list_empty(&plug->mq_list))
3239 blk_mq_flush_plug_list(plug, from_schedule);
3241 if (list_empty(&plug->list))
3244 list_splice_init(&plug->list, &list);
3246 list_sort(NULL, &list, plug_rq_cmp);
3252 * Save and disable interrupts here, to avoid doing it for every
3253 * queue lock we have to take.
3255 local_irq_save(flags);
3256 while (!list_empty(&list)) {
3257 rq = list_entry_rq(list.next);
3258 list_del_init(&rq->queuelist);
3262 * This drops the queue lock
3265 queue_unplugged(q, depth, from_schedule);
3268 spin_lock(q->queue_lock);
3272 * Short-circuit if @q is dead
3274 if (unlikely(blk_queue_dying(q))) {
3275 __blk_end_request_all(rq, -ENODEV);
3280 * rq is already accounted, so use raw insert
3282 if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA))
3283 __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
3285 __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);
3291 * This drops the queue lock
3294 queue_unplugged(q, depth, from_schedule);
3296 local_irq_restore(flags);
3299 void blk_finish_plug(struct blk_plug *plug)
3301 if (plug != current->plug)
3303 blk_flush_plug_list(plug, false);
3305 current->plug = NULL;
3307 EXPORT_SYMBOL(blk_finish_plug);
3311 * blk_pm_runtime_init - Block layer runtime PM initialization routine
3312 * @q: the queue of the device
3313 * @dev: the device the queue belongs to
3316 * Initialize runtime-PM-related fields for @q and start auto suspend for
3317 * @dev. Drivers that want to take advantage of request-based runtime PM
3318 * should call this function after @dev has been initialized, and its
3319 * request queue @q has been allocated, and runtime PM for it can not happen
3320 * yet(either due to disabled/forbidden or its usage_count > 0). In most
3321 * cases, driver should call this function before any I/O has taken place.
3323 * This function takes care of setting up using auto suspend for the device,
3324 * the autosuspend delay is set to -1 to make runtime suspend impossible
3325 * until an updated value is either set by user or by driver. Drivers do
3326 * not need to touch other autosuspend settings.
3328 * The block layer runtime PM is request based, so only works for drivers
3329 * that use request as their IO unit instead of those directly use bio's.
3331 void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
3334 q->rpm_status = RPM_ACTIVE;
3335 pm_runtime_set_autosuspend_delay(q->dev, -1);
3336 pm_runtime_use_autosuspend(q->dev);
3338 EXPORT_SYMBOL(blk_pm_runtime_init);
3341 * blk_pre_runtime_suspend - Pre runtime suspend check
3342 * @q: the queue of the device
3345 * This function will check if runtime suspend is allowed for the device
3346 * by examining if there are any requests pending in the queue. If there
3347 * are requests pending, the device can not be runtime suspended; otherwise,
3348 * the queue's status will be updated to SUSPENDING and the driver can
3349 * proceed to suspend the device.
3351 * For the not allowed case, we mark last busy for the device so that
3352 * runtime PM core will try to autosuspend it some time later.
3354 * This function should be called near the start of the device's
3355 * runtime_suspend callback.
3358 * 0 - OK to runtime suspend the device
3359 * -EBUSY - Device should not be runtime suspended
3361 int blk_pre_runtime_suspend(struct request_queue *q)
3365 spin_lock_irq(q->queue_lock);
3366 if (q->nr_pending) {
3368 pm_runtime_mark_last_busy(q->dev);
3370 q->rpm_status = RPM_SUSPENDING;
3372 spin_unlock_irq(q->queue_lock);
3375 EXPORT_SYMBOL(blk_pre_runtime_suspend);
3378 * blk_post_runtime_suspend - Post runtime suspend processing
3379 * @q: the queue of the device
3380 * @err: return value of the device's runtime_suspend function
3383 * Update the queue's runtime status according to the return value of the
3384 * device's runtime suspend function and mark last busy for the device so
3385 * that PM core will try to auto suspend the device at a later time.
3387 * This function should be called near the end of the device's
3388 * runtime_suspend callback.
3390 void blk_post_runtime_suspend(struct request_queue *q, int err)
3392 spin_lock_irq(q->queue_lock);
3394 q->rpm_status = RPM_SUSPENDED;
3396 q->rpm_status = RPM_ACTIVE;
3397 pm_runtime_mark_last_busy(q->dev);
3399 spin_unlock_irq(q->queue_lock);
3401 EXPORT_SYMBOL(blk_post_runtime_suspend);
3404 * blk_pre_runtime_resume - Pre runtime resume processing
3405 * @q: the queue of the device
3408 * Update the queue's runtime status to RESUMING in preparation for the
3409 * runtime resume of the device.
3411 * This function should be called near the start of the device's
3412 * runtime_resume callback.
3414 void blk_pre_runtime_resume(struct request_queue *q)
3416 spin_lock_irq(q->queue_lock);
3417 q->rpm_status = RPM_RESUMING;
3418 spin_unlock_irq(q->queue_lock);
3420 EXPORT_SYMBOL(blk_pre_runtime_resume);
3423 * blk_post_runtime_resume - Post runtime resume processing
3424 * @q: the queue of the device
3425 * @err: return value of the device's runtime_resume function
3428 * Update the queue's runtime status according to the return value of the
3429 * device's runtime_resume function. If it is successfully resumed, process
3430 * the requests that are queued into the device's queue when it is resuming
3431 * and then mark last busy and initiate autosuspend for it.
3433 * This function should be called near the end of the device's
3434 * runtime_resume callback.
3436 void blk_post_runtime_resume(struct request_queue *q, int err)
3438 spin_lock_irq(q->queue_lock);
3440 q->rpm_status = RPM_ACTIVE;
3442 pm_runtime_mark_last_busy(q->dev);
3443 pm_request_autosuspend(q->dev);
3445 q->rpm_status = RPM_SUSPENDED;
3447 spin_unlock_irq(q->queue_lock);
3449 EXPORT_SYMBOL(blk_post_runtime_resume);
3452 int __init blk_dev_init(void)
3454 BUILD_BUG_ON(__REQ_NR_BITS > 8 *
3455 FIELD_SIZEOF(struct request, cmd_flags));
3457 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
3458 kblockd_workqueue = alloc_workqueue("kblockd",
3459 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
3460 if (!kblockd_workqueue)
3461 panic("Failed to create kblockd\n");
3463 request_cachep = kmem_cache_create("blkdev_requests",
3464 sizeof(struct request), 0, SLAB_PANIC, NULL);
3466 blk_requestq_cachep = kmem_cache_create("blkdev_queue",
3467 sizeof(struct request_queue), 0, SLAB_PANIC, NULL);