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);
128 #ifdef CONFIG_PREEMPT_RT_FULL
129 INIT_WORK(&rq->work, __blk_mq_complete_request_remote_work);
133 rq->__sector = (sector_t) -1;
134 INIT_HLIST_NODE(&rq->hash);
135 RB_CLEAR_NODE(&rq->rb_node);
137 rq->cmd_len = BLK_MAX_CDB;
139 rq->start_time = jiffies;
140 set_start_time_ns(rq);
143 EXPORT_SYMBOL(blk_rq_init);
145 static void req_bio_endio(struct request *rq, struct bio *bio,
146 unsigned int nbytes, int error)
149 bio->bi_error = error;
151 if (unlikely(rq->cmd_flags & REQ_QUIET))
152 bio_set_flag(bio, BIO_QUIET);
154 bio_advance(bio, nbytes);
156 /* don't actually finish bio if it's part of flush sequence */
157 if (bio->bi_iter.bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ))
161 void blk_dump_rq_flags(struct request *rq, char *msg)
165 printk(KERN_INFO "%s: dev %s: type=%x, flags=%llx\n", msg,
166 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
167 (unsigned long long) rq->cmd_flags);
169 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n",
170 (unsigned long long)blk_rq_pos(rq),
171 blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
172 printk(KERN_INFO " bio %p, biotail %p, len %u\n",
173 rq->bio, rq->biotail, blk_rq_bytes(rq));
175 if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
176 printk(KERN_INFO " cdb: ");
177 for (bit = 0; bit < BLK_MAX_CDB; bit++)
178 printk("%02x ", rq->cmd[bit]);
182 EXPORT_SYMBOL(blk_dump_rq_flags);
184 static void blk_delay_work(struct work_struct *work)
186 struct request_queue *q;
188 q = container_of(work, struct request_queue, delay_work.work);
189 spin_lock_irq(q->queue_lock);
191 spin_unlock_irq(q->queue_lock);
195 * blk_delay_queue - restart queueing after defined interval
196 * @q: The &struct request_queue in question
197 * @msecs: Delay in msecs
200 * Sometimes queueing needs to be postponed for a little while, to allow
201 * resources to come back. This function will make sure that queueing is
202 * restarted around the specified time. Queue lock must be held.
204 void blk_delay_queue(struct request_queue *q, unsigned long msecs)
206 if (likely(!blk_queue_dead(q)))
207 queue_delayed_work(kblockd_workqueue, &q->delay_work,
208 msecs_to_jiffies(msecs));
210 EXPORT_SYMBOL(blk_delay_queue);
213 * blk_start_queue_async - asynchronously restart a previously stopped queue
214 * @q: The &struct request_queue in question
217 * blk_start_queue_async() will clear the stop flag on the queue, and
218 * ensure that the request_fn for the queue is run from an async
221 void blk_start_queue_async(struct request_queue *q)
223 queue_flag_clear(QUEUE_FLAG_STOPPED, q);
224 blk_run_queue_async(q);
226 EXPORT_SYMBOL(blk_start_queue_async);
229 * blk_start_queue - restart a previously stopped queue
230 * @q: The &struct request_queue in question
233 * blk_start_queue() will clear the stop flag on the queue, and call
234 * the request_fn for the queue if it was in a stopped state when
235 * entered. Also see blk_stop_queue(). Queue lock must be held.
237 void blk_start_queue(struct request_queue *q)
239 WARN_ON_NONRT(!irqs_disabled());
241 queue_flag_clear(QUEUE_FLAG_STOPPED, q);
244 EXPORT_SYMBOL(blk_start_queue);
247 * blk_stop_queue - stop a queue
248 * @q: The &struct request_queue in question
251 * The Linux block layer assumes that a block driver will consume all
252 * entries on the request queue when the request_fn strategy is called.
253 * Often this will not happen, because of hardware limitations (queue
254 * depth settings). If a device driver gets a 'queue full' response,
255 * or if it simply chooses not to queue more I/O at one point, it can
256 * call this function to prevent the request_fn from being called until
257 * the driver has signalled it's ready to go again. This happens by calling
258 * blk_start_queue() to restart queue operations. Queue lock must be held.
260 void blk_stop_queue(struct request_queue *q)
262 cancel_delayed_work(&q->delay_work);
263 queue_flag_set(QUEUE_FLAG_STOPPED, q);
265 EXPORT_SYMBOL(blk_stop_queue);
268 * blk_sync_queue - cancel any pending callbacks on a queue
272 * The block layer may perform asynchronous callback activity
273 * on a queue, such as calling the unplug function after a timeout.
274 * A block device may call blk_sync_queue to ensure that any
275 * such activity is cancelled, thus allowing it to release resources
276 * that the callbacks might use. The caller must already have made sure
277 * that its ->make_request_fn will not re-add plugging prior to calling
280 * This function does not cancel any asynchronous activity arising
281 * out of elevator or throttling code. That would require elevator_exit()
282 * and blkcg_exit_queue() to be called with queue lock initialized.
285 void blk_sync_queue(struct request_queue *q)
287 del_timer_sync(&q->timeout);
290 struct blk_mq_hw_ctx *hctx;
293 queue_for_each_hw_ctx(q, hctx, i) {
294 cancel_delayed_work_sync(&hctx->run_work);
295 cancel_delayed_work_sync(&hctx->delay_work);
298 cancel_delayed_work_sync(&q->delay_work);
301 EXPORT_SYMBOL(blk_sync_queue);
304 * __blk_run_queue_uncond - run a queue whether or not it has been stopped
305 * @q: The queue to run
308 * Invoke request handling on a queue if there are any pending requests.
309 * May be used to restart request handling after a request has completed.
310 * This variant runs the queue whether or not the queue has been
311 * stopped. Must be called with the queue lock held and interrupts
312 * disabled. See also @blk_run_queue.
314 inline void __blk_run_queue_uncond(struct request_queue *q)
316 if (unlikely(blk_queue_dead(q)))
320 * Some request_fn implementations, e.g. scsi_request_fn(), unlock
321 * the queue lock internally. As a result multiple threads may be
322 * running such a request function concurrently. Keep track of the
323 * number of active request_fn invocations such that blk_drain_queue()
324 * can wait until all these request_fn calls have finished.
326 q->request_fn_active++;
328 q->request_fn_active--;
330 EXPORT_SYMBOL_GPL(__blk_run_queue_uncond);
333 * __blk_run_queue - run a single device queue
334 * @q: The queue to run
337 * See @blk_run_queue. This variant must be called with the queue lock
338 * held and interrupts disabled.
340 void __blk_run_queue(struct request_queue *q)
342 if (unlikely(blk_queue_stopped(q)))
345 __blk_run_queue_uncond(q);
347 EXPORT_SYMBOL(__blk_run_queue);
350 * blk_run_queue_async - run a single device queue in workqueue context
351 * @q: The queue to run
354 * Tells kblockd to perform the equivalent of @blk_run_queue on behalf
355 * of us. The caller must hold the queue lock.
357 void blk_run_queue_async(struct request_queue *q)
359 if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q)))
360 mod_delayed_work(kblockd_workqueue, &q->delay_work, 0);
362 EXPORT_SYMBOL(blk_run_queue_async);
365 * blk_run_queue - run a single device queue
366 * @q: The queue to run
369 * Invoke request handling on this queue, if it has pending work to do.
370 * May be used to restart queueing when a request has completed.
372 void blk_run_queue(struct request_queue *q)
376 spin_lock_irqsave(q->queue_lock, flags);
378 spin_unlock_irqrestore(q->queue_lock, flags);
380 EXPORT_SYMBOL(blk_run_queue);
382 void blk_put_queue(struct request_queue *q)
384 kobject_put(&q->kobj);
386 EXPORT_SYMBOL(blk_put_queue);
389 * __blk_drain_queue - drain requests from request_queue
391 * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
393 * Drain requests from @q. If @drain_all is set, all requests are drained.
394 * If not, only ELVPRIV requests are drained. The caller is responsible
395 * for ensuring that no new requests which need to be drained are queued.
397 static void __blk_drain_queue(struct request_queue *q, bool drain_all)
398 __releases(q->queue_lock)
399 __acquires(q->queue_lock)
403 lockdep_assert_held(q->queue_lock);
409 * The caller might be trying to drain @q before its
410 * elevator is initialized.
413 elv_drain_elevator(q);
415 blkcg_drain_queue(q);
418 * This function might be called on a queue which failed
419 * driver init after queue creation or is not yet fully
420 * active yet. Some drivers (e.g. fd and loop) get unhappy
421 * in such cases. Kick queue iff dispatch queue has
422 * something on it and @q has request_fn set.
424 if (!list_empty(&q->queue_head) && q->request_fn)
427 drain |= q->nr_rqs_elvpriv;
428 drain |= q->request_fn_active;
431 * Unfortunately, requests are queued at and tracked from
432 * multiple places and there's no single counter which can
433 * be drained. Check all the queues and counters.
436 struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
437 drain |= !list_empty(&q->queue_head);
438 for (i = 0; i < 2; i++) {
439 drain |= q->nr_rqs[i];
440 drain |= q->in_flight[i];
442 drain |= !list_empty(&fq->flush_queue[i]);
449 spin_unlock_irq(q->queue_lock);
453 spin_lock_irq(q->queue_lock);
457 * With queue marked dead, any woken up waiter will fail the
458 * allocation path, so the wakeup chaining is lost and we're
459 * left with hung waiters. We need to wake up those waiters.
462 struct request_list *rl;
464 blk_queue_for_each_rl(rl, q)
465 for (i = 0; i < ARRAY_SIZE(rl->wait); i++)
466 wake_up_all(&rl->wait[i]);
471 * blk_queue_bypass_start - enter queue bypass mode
472 * @q: queue of interest
474 * In bypass mode, only the dispatch FIFO queue of @q is used. This
475 * function makes @q enter bypass mode and drains all requests which were
476 * throttled or issued before. On return, it's guaranteed that no request
477 * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
478 * inside queue or RCU read lock.
480 void blk_queue_bypass_start(struct request_queue *q)
482 spin_lock_irq(q->queue_lock);
484 queue_flag_set(QUEUE_FLAG_BYPASS, q);
485 spin_unlock_irq(q->queue_lock);
488 * Queues start drained. Skip actual draining till init is
489 * complete. This avoids lenghty delays during queue init which
490 * can happen many times during boot.
492 if (blk_queue_init_done(q)) {
493 spin_lock_irq(q->queue_lock);
494 __blk_drain_queue(q, false);
495 spin_unlock_irq(q->queue_lock);
497 /* ensure blk_queue_bypass() is %true inside RCU read lock */
501 EXPORT_SYMBOL_GPL(blk_queue_bypass_start);
504 * blk_queue_bypass_end - leave queue bypass mode
505 * @q: queue of interest
507 * Leave bypass mode and restore the normal queueing behavior.
509 void blk_queue_bypass_end(struct request_queue *q)
511 spin_lock_irq(q->queue_lock);
512 if (!--q->bypass_depth)
513 queue_flag_clear(QUEUE_FLAG_BYPASS, q);
514 WARN_ON_ONCE(q->bypass_depth < 0);
515 spin_unlock_irq(q->queue_lock);
517 EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
519 void blk_set_queue_dying(struct request_queue *q)
521 queue_flag_set_unlocked(QUEUE_FLAG_DYING, q);
524 blk_mq_wake_waiters(q);
526 struct request_list *rl;
528 blk_queue_for_each_rl(rl, q) {
530 wake_up(&rl->wait[BLK_RW_SYNC]);
531 wake_up(&rl->wait[BLK_RW_ASYNC]);
536 EXPORT_SYMBOL_GPL(blk_set_queue_dying);
539 * blk_cleanup_queue - shutdown a request queue
540 * @q: request queue to shutdown
542 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
543 * put it. All future requests will be failed immediately with -ENODEV.
545 void blk_cleanup_queue(struct request_queue *q)
547 spinlock_t *lock = q->queue_lock;
549 /* mark @q DYING, no new request or merges will be allowed afterwards */
550 mutex_lock(&q->sysfs_lock);
551 blk_set_queue_dying(q);
555 * A dying queue is permanently in bypass mode till released. Note
556 * that, unlike blk_queue_bypass_start(), we aren't performing
557 * synchronize_rcu() after entering bypass mode to avoid the delay
558 * as some drivers create and destroy a lot of queues while
559 * probing. This is still safe because blk_release_queue() will be
560 * called only after the queue refcnt drops to zero and nothing,
561 * RCU or not, would be traversing the queue by then.
564 queue_flag_set(QUEUE_FLAG_BYPASS, q);
566 queue_flag_set(QUEUE_FLAG_NOMERGES, q);
567 queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
568 queue_flag_set(QUEUE_FLAG_DYING, q);
569 spin_unlock_irq(lock);
570 mutex_unlock(&q->sysfs_lock);
573 * Drain all requests queued before DYING marking. Set DEAD flag to
574 * prevent that q->request_fn() gets invoked after draining finished.
579 __blk_drain_queue(q, true);
580 queue_flag_set(QUEUE_FLAG_DEAD, q);
581 spin_unlock_irq(lock);
583 /* for synchronous bio-based driver finish in-flight integrity i/o */
584 blk_flush_integrity();
586 /* @q won't process any more request, flush async actions */
587 del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
591 blk_mq_free_queue(q);
592 percpu_ref_exit(&q->q_usage_counter);
595 if (q->queue_lock != &q->__queue_lock)
596 q->queue_lock = &q->__queue_lock;
597 spin_unlock_irq(lock);
599 bdi_unregister(&q->backing_dev_info);
601 /* @q is and will stay empty, shutdown and put */
604 EXPORT_SYMBOL(blk_cleanup_queue);
606 /* Allocate memory local to the request queue */
607 static void *alloc_request_struct(gfp_t gfp_mask, void *data)
609 int nid = (int)(long)data;
610 return kmem_cache_alloc_node(request_cachep, gfp_mask, nid);
613 static void free_request_struct(void *element, void *unused)
615 kmem_cache_free(request_cachep, element);
618 int blk_init_rl(struct request_list *rl, struct request_queue *q,
621 if (unlikely(rl->rq_pool))
625 rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
626 rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
627 init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
628 init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
630 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, alloc_request_struct,
632 (void *)(long)q->node, gfp_mask,
640 void blk_exit_rl(struct request_list *rl)
643 mempool_destroy(rl->rq_pool);
646 struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
648 return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE);
650 EXPORT_SYMBOL(blk_alloc_queue);
652 int blk_queue_enter(struct request_queue *q, gfp_t gfp)
657 if (percpu_ref_tryget_live(&q->q_usage_counter))
660 if (!gfpflags_allow_blocking(gfp))
663 ret = swait_event_interruptible(q->mq_freeze_wq,
664 !atomic_read(&q->mq_freeze_depth) ||
666 if (blk_queue_dying(q))
673 void blk_queue_exit(struct request_queue *q)
675 percpu_ref_put(&q->q_usage_counter);
678 static void blk_queue_usage_counter_release(struct percpu_ref *ref)
680 struct request_queue *q =
681 container_of(ref, struct request_queue, q_usage_counter);
683 swake_up_all(&q->mq_freeze_wq);
686 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
688 struct request_queue *q;
691 q = kmem_cache_alloc_node(blk_requestq_cachep,
692 gfp_mask | __GFP_ZERO, node_id);
696 q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask);
700 q->bio_split = bioset_create(BIO_POOL_SIZE, 0);
704 q->backing_dev_info.ra_pages =
705 (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
706 q->backing_dev_info.capabilities = BDI_CAP_CGROUP_WRITEBACK;
707 q->backing_dev_info.name = "block";
710 err = bdi_init(&q->backing_dev_info);
714 setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
715 laptop_mode_timer_fn, (unsigned long) q);
716 setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
717 INIT_LIST_HEAD(&q->queue_head);
718 INIT_LIST_HEAD(&q->timeout_list);
719 INIT_LIST_HEAD(&q->icq_list);
720 #ifdef CONFIG_BLK_CGROUP
721 INIT_LIST_HEAD(&q->blkg_list);
723 INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);
725 kobject_init(&q->kobj, &blk_queue_ktype);
727 mutex_init(&q->sysfs_lock);
728 spin_lock_init(&q->__queue_lock);
731 * By default initialize queue_lock to internal lock and driver can
732 * override it later if need be.
734 q->queue_lock = &q->__queue_lock;
737 * A queue starts its life with bypass turned on to avoid
738 * unnecessary bypass on/off overhead and nasty surprises during
739 * init. The initial bypass will be finished when the queue is
740 * registered by blk_register_queue().
743 __set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags);
745 init_swait_queue_head(&q->mq_freeze_wq);
748 * Init percpu_ref in atomic mode so that it's faster to shutdown.
749 * See blk_register_queue() for details.
751 if (percpu_ref_init(&q->q_usage_counter,
752 blk_queue_usage_counter_release,
753 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
756 if (blkcg_init_queue(q))
762 percpu_ref_exit(&q->q_usage_counter);
764 bdi_destroy(&q->backing_dev_info);
766 bioset_free(q->bio_split);
768 ida_simple_remove(&blk_queue_ida, q->id);
770 kmem_cache_free(blk_requestq_cachep, q);
773 EXPORT_SYMBOL(blk_alloc_queue_node);
776 * blk_init_queue - prepare a request queue for use with a block device
777 * @rfn: The function to be called to process requests that have been
778 * placed on the queue.
779 * @lock: Request queue spin lock
782 * If a block device wishes to use the standard request handling procedures,
783 * which sorts requests and coalesces adjacent requests, then it must
784 * call blk_init_queue(). The function @rfn will be called when there
785 * are requests on the queue that need to be processed. If the device
786 * supports plugging, then @rfn may not be called immediately when requests
787 * are available on the queue, but may be called at some time later instead.
788 * Plugged queues are generally unplugged when a buffer belonging to one
789 * of the requests on the queue is needed, or due to memory pressure.
791 * @rfn is not required, or even expected, to remove all requests off the
792 * queue, but only as many as it can handle at a time. If it does leave
793 * requests on the queue, it is responsible for arranging that the requests
794 * get dealt with eventually.
796 * The queue spin lock must be held while manipulating the requests on the
797 * request queue; this lock will be taken also from interrupt context, so irq
798 * disabling is needed for it.
800 * Function returns a pointer to the initialized request queue, or %NULL if
804 * blk_init_queue() must be paired with a blk_cleanup_queue() call
805 * when the block device is deactivated (such as at module unload).
808 struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
810 return blk_init_queue_node(rfn, lock, NUMA_NO_NODE);
812 EXPORT_SYMBOL(blk_init_queue);
814 struct request_queue *
815 blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
817 struct request_queue *uninit_q, *q;
819 uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id);
823 q = blk_init_allocated_queue(uninit_q, rfn, lock);
825 blk_cleanup_queue(uninit_q);
829 EXPORT_SYMBOL(blk_init_queue_node);
831 static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio);
833 struct request_queue *
834 blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
840 q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, 0);
844 if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))
848 q->prep_rq_fn = NULL;
849 q->unprep_rq_fn = NULL;
850 q->queue_flags |= QUEUE_FLAG_DEFAULT;
852 /* Override internal queue lock with supplied lock pointer */
854 q->queue_lock = lock;
857 * This also sets hw/phys segments, boundary and size
859 blk_queue_make_request(q, blk_queue_bio);
861 q->sg_reserved_size = INT_MAX;
863 /* Protect q->elevator from elevator_change */
864 mutex_lock(&q->sysfs_lock);
867 if (elevator_init(q, NULL)) {
868 mutex_unlock(&q->sysfs_lock);
872 mutex_unlock(&q->sysfs_lock);
877 blk_free_flush_queue(q->fq);
880 EXPORT_SYMBOL(blk_init_allocated_queue);
882 bool blk_get_queue(struct request_queue *q)
884 if (likely(!blk_queue_dying(q))) {
891 EXPORT_SYMBOL(blk_get_queue);
893 static inline void blk_free_request(struct request_list *rl, struct request *rq)
895 if (rq->cmd_flags & REQ_ELVPRIV) {
896 elv_put_request(rl->q, rq);
898 put_io_context(rq->elv.icq->ioc);
901 mempool_free(rq, rl->rq_pool);
905 * ioc_batching returns true if the ioc is a valid batching request and
906 * should be given priority access to a request.
908 static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
914 * Make sure the process is able to allocate at least 1 request
915 * even if the batch times out, otherwise we could theoretically
918 return ioc->nr_batch_requests == q->nr_batching ||
919 (ioc->nr_batch_requests > 0
920 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
924 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
925 * will cause the process to be a "batcher" on all queues in the system. This
926 * is the behaviour we want though - once it gets a wakeup it should be given
929 static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
931 if (!ioc || ioc_batching(q, ioc))
934 ioc->nr_batch_requests = q->nr_batching;
935 ioc->last_waited = jiffies;
938 static void __freed_request(struct request_list *rl, int sync)
940 struct request_queue *q = rl->q;
942 if (rl->count[sync] < queue_congestion_off_threshold(q))
943 blk_clear_congested(rl, sync);
945 if (rl->count[sync] + 1 <= q->nr_requests) {
946 if (waitqueue_active(&rl->wait[sync]))
947 wake_up(&rl->wait[sync]);
949 blk_clear_rl_full(rl, sync);
954 * A request has just been released. Account for it, update the full and
955 * congestion status, wake up any waiters. Called under q->queue_lock.
957 static void freed_request(struct request_list *rl, unsigned int flags)
959 struct request_queue *q = rl->q;
960 int sync = rw_is_sync(flags);
964 if (flags & REQ_ELVPRIV)
967 __freed_request(rl, sync);
969 if (unlikely(rl->starved[sync ^ 1]))
970 __freed_request(rl, sync ^ 1);
973 int blk_update_nr_requests(struct request_queue *q, unsigned int nr)
975 struct request_list *rl;
976 int on_thresh, off_thresh;
978 spin_lock_irq(q->queue_lock);
980 blk_queue_congestion_threshold(q);
981 on_thresh = queue_congestion_on_threshold(q);
982 off_thresh = queue_congestion_off_threshold(q);
984 blk_queue_for_each_rl(rl, q) {
985 if (rl->count[BLK_RW_SYNC] >= on_thresh)
986 blk_set_congested(rl, BLK_RW_SYNC);
987 else if (rl->count[BLK_RW_SYNC] < off_thresh)
988 blk_clear_congested(rl, BLK_RW_SYNC);
990 if (rl->count[BLK_RW_ASYNC] >= on_thresh)
991 blk_set_congested(rl, BLK_RW_ASYNC);
992 else if (rl->count[BLK_RW_ASYNC] < off_thresh)
993 blk_clear_congested(rl, BLK_RW_ASYNC);
995 if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
996 blk_set_rl_full(rl, BLK_RW_SYNC);
998 blk_clear_rl_full(rl, BLK_RW_SYNC);
999 wake_up(&rl->wait[BLK_RW_SYNC]);
1002 if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
1003 blk_set_rl_full(rl, BLK_RW_ASYNC);
1005 blk_clear_rl_full(rl, BLK_RW_ASYNC);
1006 wake_up(&rl->wait[BLK_RW_ASYNC]);
1010 spin_unlock_irq(q->queue_lock);
1015 * Determine if elevator data should be initialized when allocating the
1016 * request associated with @bio.
1018 static bool blk_rq_should_init_elevator(struct bio *bio)
1024 * Flush requests do not use the elevator so skip initialization.
1025 * This allows a request to share the flush and elevator data.
1027 if (bio->bi_rw & (REQ_FLUSH | REQ_FUA))
1034 * rq_ioc - determine io_context for request allocation
1035 * @bio: request being allocated is for this bio (can be %NULL)
1037 * Determine io_context to use for request allocation for @bio. May return
1038 * %NULL if %current->io_context doesn't exist.
1040 static struct io_context *rq_ioc(struct bio *bio)
1042 #ifdef CONFIG_BLK_CGROUP
1043 if (bio && bio->bi_ioc)
1046 return current->io_context;
1050 * __get_request - get a free request
1051 * @rl: request list to allocate from
1052 * @rw_flags: RW and SYNC flags
1053 * @bio: bio to allocate request for (can be %NULL)
1054 * @gfp_mask: allocation mask
1056 * Get a free request from @q. This function may fail under memory
1057 * pressure or if @q is dead.
1059 * Must be called with @q->queue_lock held and,
1060 * Returns ERR_PTR on failure, with @q->queue_lock held.
1061 * Returns request pointer on success, with @q->queue_lock *not held*.
1063 static struct request *__get_request(struct request_list *rl, int rw_flags,
1064 struct bio *bio, gfp_t gfp_mask)
1066 struct request_queue *q = rl->q;
1068 struct elevator_type *et = q->elevator->type;
1069 struct io_context *ioc = rq_ioc(bio);
1070 struct io_cq *icq = NULL;
1071 const bool is_sync = rw_is_sync(rw_flags) != 0;
1074 if (unlikely(blk_queue_dying(q)))
1075 return ERR_PTR(-ENODEV);
1077 may_queue = elv_may_queue(q, rw_flags);
1078 if (may_queue == ELV_MQUEUE_NO)
1081 if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
1082 if (rl->count[is_sync]+1 >= q->nr_requests) {
1084 * The queue will fill after this allocation, so set
1085 * it as full, and mark this process as "batching".
1086 * This process will be allowed to complete a batch of
1087 * requests, others will be blocked.
1089 if (!blk_rl_full(rl, is_sync)) {
1090 ioc_set_batching(q, ioc);
1091 blk_set_rl_full(rl, is_sync);
1093 if (may_queue != ELV_MQUEUE_MUST
1094 && !ioc_batching(q, ioc)) {
1096 * The queue is full and the allocating
1097 * process is not a "batcher", and not
1098 * exempted by the IO scheduler
1100 return ERR_PTR(-ENOMEM);
1104 blk_set_congested(rl, is_sync);
1108 * Only allow batching queuers to allocate up to 50% over the defined
1109 * limit of requests, otherwise we could have thousands of requests
1110 * allocated with any setting of ->nr_requests
1112 if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
1113 return ERR_PTR(-ENOMEM);
1115 q->nr_rqs[is_sync]++;
1116 rl->count[is_sync]++;
1117 rl->starved[is_sync] = 0;
1120 * Decide whether the new request will be managed by elevator. If
1121 * so, mark @rw_flags and increment elvpriv. Non-zero elvpriv will
1122 * prevent the current elevator from being destroyed until the new
1123 * request is freed. This guarantees icq's won't be destroyed and
1124 * makes creating new ones safe.
1126 * Also, lookup icq while holding queue_lock. If it doesn't exist,
1127 * it will be created after releasing queue_lock.
1129 if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) {
1130 rw_flags |= REQ_ELVPRIV;
1131 q->nr_rqs_elvpriv++;
1132 if (et->icq_cache && ioc)
1133 icq = ioc_lookup_icq(ioc, q);
1136 if (blk_queue_io_stat(q))
1137 rw_flags |= REQ_IO_STAT;
1138 spin_unlock_irq(q->queue_lock);
1140 /* allocate and init request */
1141 rq = mempool_alloc(rl->rq_pool, gfp_mask);
1146 blk_rq_set_rl(rq, rl);
1147 rq->cmd_flags = rw_flags | REQ_ALLOCED;
1150 if (rw_flags & REQ_ELVPRIV) {
1151 if (unlikely(et->icq_cache && !icq)) {
1153 icq = ioc_create_icq(ioc, q, gfp_mask);
1159 if (unlikely(elv_set_request(q, rq, bio, gfp_mask)))
1162 /* @rq->elv.icq holds io_context until @rq is freed */
1164 get_io_context(icq->ioc);
1168 * ioc may be NULL here, and ioc_batching will be false. That's
1169 * OK, if the queue is under the request limit then requests need
1170 * not count toward the nr_batch_requests limit. There will always
1171 * be some limit enforced by BLK_BATCH_TIME.
1173 if (ioc_batching(q, ioc))
1174 ioc->nr_batch_requests--;
1176 trace_block_getrq(q, bio, rw_flags & 1);
1181 * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed
1182 * and may fail indefinitely under memory pressure and thus
1183 * shouldn't stall IO. Treat this request as !elvpriv. This will
1184 * disturb iosched and blkcg but weird is bettern than dead.
1186 printk_ratelimited(KERN_WARNING "%s: dev %s: request aux data allocation failed, iosched may be disturbed\n",
1187 __func__, dev_name(q->backing_dev_info.dev));
1189 rq->cmd_flags &= ~REQ_ELVPRIV;
1192 spin_lock_irq(q->queue_lock);
1193 q->nr_rqs_elvpriv--;
1194 spin_unlock_irq(q->queue_lock);
1199 * Allocation failed presumably due to memory. Undo anything we
1200 * might have messed up.
1202 * Allocating task should really be put onto the front of the wait
1203 * queue, but this is pretty rare.
1205 spin_lock_irq(q->queue_lock);
1206 freed_request(rl, rw_flags);
1209 * in the very unlikely event that allocation failed and no
1210 * requests for this direction was pending, mark us starved so that
1211 * freeing of a request in the other direction will notice
1212 * us. another possible fix would be to split the rq mempool into
1216 if (unlikely(rl->count[is_sync] == 0))
1217 rl->starved[is_sync] = 1;
1218 return ERR_PTR(-ENOMEM);
1222 * get_request - get a free request
1223 * @q: request_queue to allocate request from
1224 * @rw_flags: RW and SYNC flags
1225 * @bio: bio to allocate request for (can be %NULL)
1226 * @gfp_mask: allocation mask
1228 * Get a free request from @q. If %__GFP_DIRECT_RECLAIM is set in @gfp_mask,
1229 * this function keeps retrying under memory pressure and fails iff @q is dead.
1231 * Must be called with @q->queue_lock held and,
1232 * Returns ERR_PTR on failure, with @q->queue_lock held.
1233 * Returns request pointer on success, with @q->queue_lock *not held*.
1235 static struct request *get_request(struct request_queue *q, int rw_flags,
1236 struct bio *bio, gfp_t gfp_mask)
1238 const bool is_sync = rw_is_sync(rw_flags) != 0;
1240 struct request_list *rl;
1243 rl = blk_get_rl(q, bio); /* transferred to @rq on success */
1245 rq = __get_request(rl, rw_flags, bio, gfp_mask);
1249 if (!gfpflags_allow_blocking(gfp_mask) || unlikely(blk_queue_dying(q))) {
1254 /* wait on @rl and retry */
1255 prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
1256 TASK_UNINTERRUPTIBLE);
1258 trace_block_sleeprq(q, bio, rw_flags & 1);
1260 spin_unlock_irq(q->queue_lock);
1264 * After sleeping, we become a "batching" process and will be able
1265 * to allocate at least one request, and up to a big batch of them
1266 * for a small period time. See ioc_batching, ioc_set_batching
1268 ioc_set_batching(q, current->io_context);
1270 spin_lock_irq(q->queue_lock);
1271 finish_wait(&rl->wait[is_sync], &wait);
1276 static struct request *blk_old_get_request(struct request_queue *q, int rw,
1281 BUG_ON(rw != READ && rw != WRITE);
1283 /* create ioc upfront */
1284 create_io_context(gfp_mask, q->node);
1286 spin_lock_irq(q->queue_lock);
1287 rq = get_request(q, rw, NULL, gfp_mask);
1289 spin_unlock_irq(q->queue_lock);
1290 /* q->queue_lock is unlocked at this point */
1295 struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
1298 return blk_mq_alloc_request(q, rw, gfp_mask, false);
1300 return blk_old_get_request(q, rw, gfp_mask);
1302 EXPORT_SYMBOL(blk_get_request);
1305 * blk_make_request - given a bio, allocate a corresponding struct request.
1306 * @q: target request queue
1307 * @bio: The bio describing the memory mappings that will be submitted for IO.
1308 * It may be a chained-bio properly constructed by block/bio layer.
1309 * @gfp_mask: gfp flags to be used for memory allocation
1311 * blk_make_request is the parallel of generic_make_request for BLOCK_PC
1312 * type commands. Where the struct request needs to be farther initialized by
1313 * the caller. It is passed a &struct bio, which describes the memory info of
1316 * The caller of blk_make_request must make sure that bi_io_vec
1317 * are set to describe the memory buffers. That bio_data_dir() will return
1318 * the needed direction of the request. (And all bio's in the passed bio-chain
1319 * are properly set accordingly)
1321 * If called under none-sleepable conditions, mapped bio buffers must not
1322 * need bouncing, by calling the appropriate masked or flagged allocator,
1323 * suitable for the target device. Otherwise the call to blk_queue_bounce will
1326 * WARNING: When allocating/cloning a bio-chain, careful consideration should be
1327 * given to how you allocate bios. In particular, you cannot use
1328 * __GFP_DIRECT_RECLAIM for anything but the first bio in the chain. Otherwise
1329 * you risk waiting for IO completion of a bio that hasn't been submitted yet,
1330 * thus resulting in a deadlock. Alternatively bios should be allocated using
1331 * bio_kmalloc() instead of bio_alloc(), as that avoids the mempool deadlock.
1332 * If possible a big IO should be split into smaller parts when allocation
1333 * fails. Partial allocation should not be an error, or you risk a live-lock.
1335 struct request *blk_make_request(struct request_queue *q, struct bio *bio,
1338 struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask);
1343 blk_rq_set_block_pc(rq);
1346 struct bio *bounce_bio = bio;
1349 blk_queue_bounce(q, &bounce_bio);
1350 ret = blk_rq_append_bio(q, rq, bounce_bio);
1351 if (unlikely(ret)) {
1352 blk_put_request(rq);
1353 return ERR_PTR(ret);
1359 EXPORT_SYMBOL(blk_make_request);
1362 * blk_rq_set_block_pc - initialize a request to type BLOCK_PC
1363 * @rq: request to be initialized
1366 void blk_rq_set_block_pc(struct request *rq)
1368 rq->cmd_type = REQ_TYPE_BLOCK_PC;
1370 rq->__sector = (sector_t) -1;
1371 rq->bio = rq->biotail = NULL;
1372 memset(rq->__cmd, 0, sizeof(rq->__cmd));
1374 EXPORT_SYMBOL(blk_rq_set_block_pc);
1377 * blk_requeue_request - put a request back on queue
1378 * @q: request queue where request should be inserted
1379 * @rq: request to be inserted
1382 * Drivers often keep queueing requests until the hardware cannot accept
1383 * more, when that condition happens we need to put the request back
1384 * on the queue. Must be called with queue lock held.
1386 void blk_requeue_request(struct request_queue *q, struct request *rq)
1388 blk_delete_timer(rq);
1389 blk_clear_rq_complete(rq);
1390 trace_block_rq_requeue(q, rq);
1392 if (rq->cmd_flags & REQ_QUEUED)
1393 blk_queue_end_tag(q, rq);
1395 BUG_ON(blk_queued_rq(rq));
1397 elv_requeue_request(q, rq);
1399 EXPORT_SYMBOL(blk_requeue_request);
1401 static void add_acct_request(struct request_queue *q, struct request *rq,
1404 blk_account_io_start(rq, true);
1405 __elv_add_request(q, rq, where);
1408 static void part_round_stats_single(int cpu, struct hd_struct *part,
1413 if (now == part->stamp)
1416 inflight = part_in_flight(part);
1418 __part_stat_add(cpu, part, time_in_queue,
1419 inflight * (now - part->stamp));
1420 __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
1426 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1427 * @cpu: cpu number for stats access
1428 * @part: target partition
1430 * The average IO queue length and utilisation statistics are maintained
1431 * by observing the current state of the queue length and the amount of
1432 * time it has been in this state for.
1434 * Normally, that accounting is done on IO completion, but that can result
1435 * in more than a second's worth of IO being accounted for within any one
1436 * second, leading to >100% utilisation. To deal with that, we call this
1437 * function to do a round-off before returning the results when reading
1438 * /proc/diskstats. This accounts immediately for all queue usage up to
1439 * the current jiffies and restarts the counters again.
1441 void part_round_stats(int cpu, struct hd_struct *part)
1443 unsigned long now = jiffies;
1446 part_round_stats_single(cpu, &part_to_disk(part)->part0, now);
1447 part_round_stats_single(cpu, part, now);
1449 EXPORT_SYMBOL_GPL(part_round_stats);
1452 static void blk_pm_put_request(struct request *rq)
1454 if (rq->q->dev && !(rq->cmd_flags & REQ_PM) && !--rq->q->nr_pending)
1455 pm_runtime_mark_last_busy(rq->q->dev);
1458 static inline void blk_pm_put_request(struct request *rq) {}
1462 * queue lock must be held
1464 void __blk_put_request(struct request_queue *q, struct request *req)
1470 blk_mq_free_request(req);
1474 blk_pm_put_request(req);
1476 elv_completed_request(q, req);
1478 /* this is a bio leak */
1479 WARN_ON(req->bio != NULL);
1482 * Request may not have originated from ll_rw_blk. if not,
1483 * it didn't come out of our reserved rq pools
1485 if (req->cmd_flags & REQ_ALLOCED) {
1486 unsigned int flags = req->cmd_flags;
1487 struct request_list *rl = blk_rq_rl(req);
1489 BUG_ON(!list_empty(&req->queuelist));
1490 BUG_ON(ELV_ON_HASH(req));
1492 blk_free_request(rl, req);
1493 freed_request(rl, flags);
1497 EXPORT_SYMBOL_GPL(__blk_put_request);
1499 void blk_put_request(struct request *req)
1501 struct request_queue *q = req->q;
1504 blk_mq_free_request(req);
1506 unsigned long flags;
1508 spin_lock_irqsave(q->queue_lock, flags);
1509 __blk_put_request(q, req);
1510 spin_unlock_irqrestore(q->queue_lock, flags);
1513 EXPORT_SYMBOL(blk_put_request);
1516 * blk_add_request_payload - add a payload to a request
1517 * @rq: request to update
1518 * @page: page backing the payload
1519 * @len: length of the payload.
1521 * This allows to later add a payload to an already submitted request by
1522 * a block driver. The driver needs to take care of freeing the payload
1525 * Note that this is a quite horrible hack and nothing but handling of
1526 * discard requests should ever use it.
1528 void blk_add_request_payload(struct request *rq, struct page *page,
1531 struct bio *bio = rq->bio;
1533 bio->bi_io_vec->bv_page = page;
1534 bio->bi_io_vec->bv_offset = 0;
1535 bio->bi_io_vec->bv_len = len;
1537 bio->bi_iter.bi_size = len;
1539 bio->bi_phys_segments = 1;
1541 rq->__data_len = rq->resid_len = len;
1542 rq->nr_phys_segments = 1;
1544 EXPORT_SYMBOL_GPL(blk_add_request_payload);
1546 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
1549 const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
1551 if (!ll_back_merge_fn(q, req, bio))
1554 trace_block_bio_backmerge(q, req, bio);
1556 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1557 blk_rq_set_mixed_merge(req);
1559 req->biotail->bi_next = bio;
1561 req->__data_len += bio->bi_iter.bi_size;
1562 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1564 blk_account_io_start(req, false);
1568 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
1571 const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
1573 if (!ll_front_merge_fn(q, req, bio))
1576 trace_block_bio_frontmerge(q, req, bio);
1578 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1579 blk_rq_set_mixed_merge(req);
1581 bio->bi_next = req->bio;
1584 req->__sector = bio->bi_iter.bi_sector;
1585 req->__data_len += bio->bi_iter.bi_size;
1586 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1588 blk_account_io_start(req, false);
1593 * blk_attempt_plug_merge - try to merge with %current's plugged list
1594 * @q: request_queue new bio is being queued at
1595 * @bio: new bio being queued
1596 * @request_count: out parameter for number of traversed plugged requests
1597 * @same_queue_rq: pointer to &struct request that gets filled in when
1598 * another request associated with @q is found on the plug list
1599 * (optional, may be %NULL)
1601 * Determine whether @bio being queued on @q can be merged with a request
1602 * on %current's plugged list. Returns %true if merge was successful,
1605 * Plugging coalesces IOs from the same issuer for the same purpose without
1606 * going through @q->queue_lock. As such it's more of an issuing mechanism
1607 * than scheduling, and the request, while may have elvpriv data, is not
1608 * added on the elevator at this point. In addition, we don't have
1609 * reliable access to the elevator outside queue lock. Only check basic
1610 * merging parameters without querying the elevator.
1612 * Caller must ensure !blk_queue_nomerges(q) beforehand.
1614 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
1615 unsigned int *request_count,
1616 struct request **same_queue_rq)
1618 struct blk_plug *plug;
1621 struct list_head *plug_list;
1623 plug = current->plug;
1629 plug_list = &plug->mq_list;
1631 plug_list = &plug->list;
1633 list_for_each_entry_reverse(rq, plug_list, queuelist) {
1639 * Only blk-mq multiple hardware queues case checks the
1640 * rq in the same queue, there should be only one such
1644 *same_queue_rq = rq;
1647 if (rq->q != q || !blk_rq_merge_ok(rq, bio))
1650 el_ret = blk_try_merge(rq, bio);
1651 if (el_ret == ELEVATOR_BACK_MERGE) {
1652 ret = bio_attempt_back_merge(q, rq, bio);
1655 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
1656 ret = bio_attempt_front_merge(q, rq, bio);
1665 unsigned int blk_plug_queued_count(struct request_queue *q)
1667 struct blk_plug *plug;
1669 struct list_head *plug_list;
1670 unsigned int ret = 0;
1672 plug = current->plug;
1677 plug_list = &plug->mq_list;
1679 plug_list = &plug->list;
1681 list_for_each_entry(rq, plug_list, queuelist) {
1689 void init_request_from_bio(struct request *req, struct bio *bio)
1691 req->cmd_type = REQ_TYPE_FS;
1693 req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK;
1694 if (bio->bi_rw & REQ_RAHEAD)
1695 req->cmd_flags |= REQ_FAILFAST_MASK;
1698 req->__sector = bio->bi_iter.bi_sector;
1699 req->ioprio = bio_prio(bio);
1700 blk_rq_bio_prep(req->q, req, bio);
1703 static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
1705 const bool sync = !!(bio->bi_rw & REQ_SYNC);
1706 struct blk_plug *plug;
1707 int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT;
1708 struct request *req;
1709 unsigned int request_count = 0;
1712 * low level driver can indicate that it wants pages above a
1713 * certain limit bounced to low memory (ie for highmem, or even
1714 * ISA dma in theory)
1716 blk_queue_bounce(q, &bio);
1718 blk_queue_split(q, &bio, q->bio_split);
1720 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1721 bio->bi_error = -EIO;
1723 return BLK_QC_T_NONE;
1726 if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
1727 spin_lock_irq(q->queue_lock);
1728 where = ELEVATOR_INSERT_FLUSH;
1733 * Check if we can merge with the plugged list before grabbing
1736 if (!blk_queue_nomerges(q)) {
1737 if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
1738 return BLK_QC_T_NONE;
1740 request_count = blk_plug_queued_count(q);
1742 spin_lock_irq(q->queue_lock);
1744 el_ret = elv_merge(q, &req, bio);
1745 if (el_ret == ELEVATOR_BACK_MERGE) {
1746 if (bio_attempt_back_merge(q, req, bio)) {
1747 elv_bio_merged(q, req, bio);
1748 if (!attempt_back_merge(q, req))
1749 elv_merged_request(q, req, el_ret);
1752 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
1753 if (bio_attempt_front_merge(q, req, bio)) {
1754 elv_bio_merged(q, req, bio);
1755 if (!attempt_front_merge(q, req))
1756 elv_merged_request(q, req, el_ret);
1763 * This sync check and mask will be re-done in init_request_from_bio(),
1764 * but we need to set it earlier to expose the sync flag to the
1765 * rq allocator and io schedulers.
1767 rw_flags = bio_data_dir(bio);
1769 rw_flags |= REQ_SYNC;
1772 * Grab a free request. This is might sleep but can not fail.
1773 * Returns with the queue unlocked.
1775 req = get_request(q, rw_flags, bio, GFP_NOIO);
1777 bio->bi_error = PTR_ERR(req);
1783 * After dropping the lock and possibly sleeping here, our request
1784 * may now be mergeable after it had proven unmergeable (above).
1785 * We don't worry about that case for efficiency. It won't happen
1786 * often, and the elevators are able to handle it.
1788 init_request_from_bio(req, bio);
1790 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags))
1791 req->cpu = raw_smp_processor_id();
1793 plug = current->plug;
1796 * If this is the first request added after a plug, fire
1800 trace_block_plug(q);
1802 if (request_count >= BLK_MAX_REQUEST_COUNT) {
1803 blk_flush_plug_list(plug, false);
1804 trace_block_plug(q);
1807 list_add_tail(&req->queuelist, &plug->list);
1808 blk_account_io_start(req, true);
1810 spin_lock_irq(q->queue_lock);
1811 add_acct_request(q, req, where);
1814 spin_unlock_irq(q->queue_lock);
1817 return BLK_QC_T_NONE;
1821 * If bio->bi_dev is a partition, remap the location
1823 static inline void blk_partition_remap(struct bio *bio)
1825 struct block_device *bdev = bio->bi_bdev;
1827 if (bio_sectors(bio) && bdev != bdev->bd_contains) {
1828 struct hd_struct *p = bdev->bd_part;
1830 bio->bi_iter.bi_sector += p->start_sect;
1831 bio->bi_bdev = bdev->bd_contains;
1833 trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio,
1835 bio->bi_iter.bi_sector - p->start_sect);
1839 static void handle_bad_sector(struct bio *bio)
1841 char b[BDEVNAME_SIZE];
1843 printk(KERN_INFO "attempt to access beyond end of device\n");
1844 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
1845 bdevname(bio->bi_bdev, b),
1847 (unsigned long long)bio_end_sector(bio),
1848 (long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9));
1851 #ifdef CONFIG_FAIL_MAKE_REQUEST
1853 static DECLARE_FAULT_ATTR(fail_make_request);
1855 static int __init setup_fail_make_request(char *str)
1857 return setup_fault_attr(&fail_make_request, str);
1859 __setup("fail_make_request=", setup_fail_make_request);
1861 static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
1863 return part->make_it_fail && should_fail(&fail_make_request, bytes);
1866 static int __init fail_make_request_debugfs(void)
1868 struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
1869 NULL, &fail_make_request);
1871 return PTR_ERR_OR_ZERO(dir);
1874 late_initcall(fail_make_request_debugfs);
1876 #else /* CONFIG_FAIL_MAKE_REQUEST */
1878 static inline bool should_fail_request(struct hd_struct *part,
1884 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1887 * Check whether this bio extends beyond the end of the device.
1889 static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
1896 /* Test device or partition size, when known. */
1897 maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
1899 sector_t sector = bio->bi_iter.bi_sector;
1901 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
1903 * This may well happen - the kernel calls bread()
1904 * without checking the size of the device, e.g., when
1905 * mounting a device.
1907 handle_bad_sector(bio);
1915 static noinline_for_stack bool
1916 generic_make_request_checks(struct bio *bio)
1918 struct request_queue *q;
1919 int nr_sectors = bio_sectors(bio);
1921 char b[BDEVNAME_SIZE];
1922 struct hd_struct *part;
1926 if (bio_check_eod(bio, nr_sectors))
1929 q = bdev_get_queue(bio->bi_bdev);
1932 "generic_make_request: Trying to access "
1933 "nonexistent block-device %s (%Lu)\n",
1934 bdevname(bio->bi_bdev, b),
1935 (long long) bio->bi_iter.bi_sector);
1939 part = bio->bi_bdev->bd_part;
1940 if (should_fail_request(part, bio->bi_iter.bi_size) ||
1941 should_fail_request(&part_to_disk(part)->part0,
1942 bio->bi_iter.bi_size))
1946 * If this device has partitions, remap block n
1947 * of partition p to block n+start(p) of the disk.
1949 blk_partition_remap(bio);
1951 if (bio_check_eod(bio, nr_sectors))
1955 * Filter flush bio's early so that make_request based
1956 * drivers without flush support don't have to worry
1959 if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) {
1960 bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA);
1967 if ((bio->bi_rw & REQ_DISCARD) &&
1968 (!blk_queue_discard(q) ||
1969 ((bio->bi_rw & REQ_SECURE) && !blk_queue_secdiscard(q)))) {
1974 if (bio->bi_rw & REQ_WRITE_SAME && !bdev_write_same(bio->bi_bdev)) {
1980 * Various block parts want %current->io_context and lazy ioc
1981 * allocation ends up trading a lot of pain for a small amount of
1982 * memory. Just allocate it upfront. This may fail and block
1983 * layer knows how to live with it.
1985 create_io_context(GFP_ATOMIC, q->node);
1987 if (!blkcg_bio_issue_check(q, bio))
1990 trace_block_bio_queue(q, bio);
1994 bio->bi_error = err;
2000 * generic_make_request - hand a buffer to its device driver for I/O
2001 * @bio: The bio describing the location in memory and on the device.
2003 * generic_make_request() is used to make I/O requests of block
2004 * devices. It is passed a &struct bio, which describes the I/O that needs
2007 * generic_make_request() does not return any status. The
2008 * success/failure status of the request, along with notification of
2009 * completion, is delivered asynchronously through the bio->bi_end_io
2010 * function described (one day) else where.
2012 * The caller of generic_make_request must make sure that bi_io_vec
2013 * are set to describe the memory buffer, and that bi_dev and bi_sector are
2014 * set to describe the device address, and the
2015 * bi_end_io and optionally bi_private are set to describe how
2016 * completion notification should be signaled.
2018 * generic_make_request and the drivers it calls may use bi_next if this
2019 * bio happens to be merged with someone else, and may resubmit the bio to
2020 * a lower device by calling into generic_make_request recursively, which
2021 * means the bio should NOT be touched after the call to ->make_request_fn.
2023 blk_qc_t generic_make_request(struct bio *bio)
2025 struct bio_list bio_list_on_stack;
2026 blk_qc_t ret = BLK_QC_T_NONE;
2028 if (!generic_make_request_checks(bio))
2032 * We only want one ->make_request_fn to be active at a time, else
2033 * stack usage with stacked devices could be a problem. So use
2034 * current->bio_list to keep a list of requests submited by a
2035 * make_request_fn function. current->bio_list is also used as a
2036 * flag to say if generic_make_request is currently active in this
2037 * task or not. If it is NULL, then no make_request is active. If
2038 * it is non-NULL, then a make_request is active, and new requests
2039 * should be added at the tail
2041 if (current->bio_list) {
2042 bio_list_add(current->bio_list, bio);
2046 /* following loop may be a bit non-obvious, and so deserves some
2048 * Before entering the loop, bio->bi_next is NULL (as all callers
2049 * ensure that) so we have a list with a single bio.
2050 * We pretend that we have just taken it off a longer list, so
2051 * we assign bio_list to a pointer to the bio_list_on_stack,
2052 * thus initialising the bio_list of new bios to be
2053 * added. ->make_request() may indeed add some more bios
2054 * through a recursive call to generic_make_request. If it
2055 * did, we find a non-NULL value in bio_list and re-enter the loop
2056 * from the top. In this case we really did just take the bio
2057 * of the top of the list (no pretending) and so remove it from
2058 * bio_list, and call into ->make_request() again.
2060 BUG_ON(bio->bi_next);
2061 bio_list_init(&bio_list_on_stack);
2062 current->bio_list = &bio_list_on_stack;
2064 struct request_queue *q = bdev_get_queue(bio->bi_bdev);
2066 if (likely(blk_queue_enter(q, __GFP_DIRECT_RECLAIM) == 0)) {
2068 ret = q->make_request_fn(q, bio);
2072 bio = bio_list_pop(current->bio_list);
2074 struct bio *bio_next = bio_list_pop(current->bio_list);
2080 current->bio_list = NULL; /* deactivate */
2085 EXPORT_SYMBOL(generic_make_request);
2088 * submit_bio - submit a bio to the block device layer for I/O
2089 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
2090 * @bio: The &struct bio which describes the I/O
2092 * submit_bio() is very similar in purpose to generic_make_request(), and
2093 * uses that function to do most of the work. Both are fairly rough
2094 * interfaces; @bio must be presetup and ready for I/O.
2097 blk_qc_t submit_bio(int rw, struct bio *bio)
2102 * If it's a regular read/write or a barrier with data attached,
2103 * go through the normal accounting stuff before submission.
2105 if (bio_has_data(bio)) {
2108 if (unlikely(rw & REQ_WRITE_SAME))
2109 count = bdev_logical_block_size(bio->bi_bdev) >> 9;
2111 count = bio_sectors(bio);
2114 count_vm_events(PGPGOUT, count);
2116 task_io_account_read(bio->bi_iter.bi_size);
2117 count_vm_events(PGPGIN, count);
2120 if (unlikely(block_dump)) {
2121 char b[BDEVNAME_SIZE];
2122 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
2123 current->comm, task_pid_nr(current),
2124 (rw & WRITE) ? "WRITE" : "READ",
2125 (unsigned long long)bio->bi_iter.bi_sector,
2126 bdevname(bio->bi_bdev, b),
2131 return generic_make_request(bio);
2133 EXPORT_SYMBOL(submit_bio);
2136 * blk_cloned_rq_check_limits - Helper function to check a cloned request
2137 * for new the queue limits
2139 * @rq: the request being checked
2142 * @rq may have been made based on weaker limitations of upper-level queues
2143 * in request stacking drivers, and it may violate the limitation of @q.
2144 * Since the block layer and the underlying device driver trust @rq
2145 * after it is inserted to @q, it should be checked against @q before
2146 * the insertion using this generic function.
2148 * Request stacking drivers like request-based dm may change the queue
2149 * limits when retrying requests on other queues. Those requests need
2150 * to be checked against the new queue limits again during dispatch.
2152 static int blk_cloned_rq_check_limits(struct request_queue *q,
2155 if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, rq->cmd_flags)) {
2156 printk(KERN_ERR "%s: over max size limit.\n", __func__);
2161 * queue's settings related to segment counting like q->bounce_pfn
2162 * may differ from that of other stacking queues.
2163 * Recalculate it to check the request correctly on this queue's
2166 blk_recalc_rq_segments(rq);
2167 if (rq->nr_phys_segments > queue_max_segments(q)) {
2168 printk(KERN_ERR "%s: over max segments limit.\n", __func__);
2176 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
2177 * @q: the queue to submit the request
2178 * @rq: the request being queued
2180 int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
2182 unsigned long flags;
2183 int where = ELEVATOR_INSERT_BACK;
2185 if (blk_cloned_rq_check_limits(q, rq))
2189 should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
2193 if (blk_queue_io_stat(q))
2194 blk_account_io_start(rq, true);
2195 blk_mq_insert_request(rq, false, true, true);
2199 spin_lock_irqsave(q->queue_lock, flags);
2200 if (unlikely(blk_queue_dying(q))) {
2201 spin_unlock_irqrestore(q->queue_lock, flags);
2206 * Submitting request must be dequeued before calling this function
2207 * because it will be linked to another request_queue
2209 BUG_ON(blk_queued_rq(rq));
2211 if (rq->cmd_flags & (REQ_FLUSH|REQ_FUA))
2212 where = ELEVATOR_INSERT_FLUSH;
2214 add_acct_request(q, rq, where);
2215 if (where == ELEVATOR_INSERT_FLUSH)
2217 spin_unlock_irqrestore(q->queue_lock, flags);
2221 EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
2224 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
2225 * @rq: request to examine
2228 * A request could be merge of IOs which require different failure
2229 * handling. This function determines the number of bytes which
2230 * can be failed from the beginning of the request without
2231 * crossing into area which need to be retried further.
2234 * The number of bytes to fail.
2237 * queue_lock must be held.
2239 unsigned int blk_rq_err_bytes(const struct request *rq)
2241 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
2242 unsigned int bytes = 0;
2245 if (!(rq->cmd_flags & REQ_MIXED_MERGE))
2246 return blk_rq_bytes(rq);
2249 * Currently the only 'mixing' which can happen is between
2250 * different fastfail types. We can safely fail portions
2251 * which have all the failfast bits that the first one has -
2252 * the ones which are at least as eager to fail as the first
2255 for (bio = rq->bio; bio; bio = bio->bi_next) {
2256 if ((bio->bi_rw & ff) != ff)
2258 bytes += bio->bi_iter.bi_size;
2261 /* this could lead to infinite loop */
2262 BUG_ON(blk_rq_bytes(rq) && !bytes);
2265 EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
2267 void blk_account_io_completion(struct request *req, unsigned int bytes)
2269 if (blk_do_io_stat(req)) {
2270 const int rw = rq_data_dir(req);
2271 struct hd_struct *part;
2274 cpu = part_stat_lock();
2276 part_stat_add(cpu, part, sectors[rw], bytes >> 9);
2281 void blk_account_io_done(struct request *req)
2284 * Account IO completion. flush_rq isn't accounted as a
2285 * normal IO on queueing nor completion. Accounting the
2286 * containing request is enough.
2288 if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) {
2289 unsigned long duration = jiffies - req->start_time;
2290 const int rw = rq_data_dir(req);
2291 struct hd_struct *part;
2294 cpu = part_stat_lock();
2297 part_stat_inc(cpu, part, ios[rw]);
2298 part_stat_add(cpu, part, ticks[rw], duration);
2299 part_round_stats(cpu, part);
2300 part_dec_in_flight(part, rw);
2302 hd_struct_put(part);
2309 * Don't process normal requests when queue is suspended
2310 * or in the process of suspending/resuming
2312 static struct request *blk_pm_peek_request(struct request_queue *q,
2315 if (q->dev && (q->rpm_status == RPM_SUSPENDED ||
2316 (q->rpm_status != RPM_ACTIVE && !(rq->cmd_flags & REQ_PM))))
2322 static inline struct request *blk_pm_peek_request(struct request_queue *q,
2329 void blk_account_io_start(struct request *rq, bool new_io)
2331 struct hd_struct *part;
2332 int rw = rq_data_dir(rq);
2335 if (!blk_do_io_stat(rq))
2338 cpu = part_stat_lock();
2342 part_stat_inc(cpu, part, merges[rw]);
2344 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
2345 if (!hd_struct_try_get(part)) {
2347 * The partition is already being removed,
2348 * the request will be accounted on the disk only
2350 * We take a reference on disk->part0 although that
2351 * partition will never be deleted, so we can treat
2352 * it as any other partition.
2354 part = &rq->rq_disk->part0;
2355 hd_struct_get(part);
2357 part_round_stats(cpu, part);
2358 part_inc_in_flight(part, rw);
2366 * blk_peek_request - peek at the top of a request queue
2367 * @q: request queue to peek at
2370 * Return the request at the top of @q. The returned request
2371 * should be started using blk_start_request() before LLD starts
2375 * Pointer to the request at the top of @q if available. Null
2379 * queue_lock must be held.
2381 struct request *blk_peek_request(struct request_queue *q)
2386 while ((rq = __elv_next_request(q)) != NULL) {
2388 rq = blk_pm_peek_request(q, rq);
2392 if (!(rq->cmd_flags & REQ_STARTED)) {
2394 * This is the first time the device driver
2395 * sees this request (possibly after
2396 * requeueing). Notify IO scheduler.
2398 if (rq->cmd_flags & REQ_SORTED)
2399 elv_activate_rq(q, rq);
2402 * just mark as started even if we don't start
2403 * it, a request that has been delayed should
2404 * not be passed by new incoming requests
2406 rq->cmd_flags |= REQ_STARTED;
2407 trace_block_rq_issue(q, rq);
2410 if (!q->boundary_rq || q->boundary_rq == rq) {
2411 q->end_sector = rq_end_sector(rq);
2412 q->boundary_rq = NULL;
2415 if (rq->cmd_flags & REQ_DONTPREP)
2418 if (q->dma_drain_size && blk_rq_bytes(rq)) {
2420 * make sure space for the drain appears we
2421 * know we can do this because max_hw_segments
2422 * has been adjusted to be one fewer than the
2425 rq->nr_phys_segments++;
2431 ret = q->prep_rq_fn(q, rq);
2432 if (ret == BLKPREP_OK) {
2434 } else if (ret == BLKPREP_DEFER) {
2436 * the request may have been (partially) prepped.
2437 * we need to keep this request in the front to
2438 * avoid resource deadlock. REQ_STARTED will
2439 * prevent other fs requests from passing this one.
2441 if (q->dma_drain_size && blk_rq_bytes(rq) &&
2442 !(rq->cmd_flags & REQ_DONTPREP)) {
2444 * remove the space for the drain we added
2445 * so that we don't add it again
2447 --rq->nr_phys_segments;
2452 } else if (ret == BLKPREP_KILL) {
2453 rq->cmd_flags |= REQ_QUIET;
2455 * Mark this request as started so we don't trigger
2456 * any debug logic in the end I/O path.
2458 blk_start_request(rq);
2459 __blk_end_request_all(rq, -EIO);
2461 printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
2468 EXPORT_SYMBOL(blk_peek_request);
2470 void blk_dequeue_request(struct request *rq)
2472 struct request_queue *q = rq->q;
2474 BUG_ON(list_empty(&rq->queuelist));
2475 BUG_ON(ELV_ON_HASH(rq));
2477 list_del_init(&rq->queuelist);
2480 * the time frame between a request being removed from the lists
2481 * and to it is freed is accounted as io that is in progress at
2484 if (blk_account_rq(rq)) {
2485 q->in_flight[rq_is_sync(rq)]++;
2486 set_io_start_time_ns(rq);
2491 * blk_start_request - start request processing on the driver
2492 * @req: request to dequeue
2495 * Dequeue @req and start timeout timer on it. This hands off the
2496 * request to the driver.
2498 * Block internal functions which don't want to start timer should
2499 * call blk_dequeue_request().
2502 * queue_lock must be held.
2504 void blk_start_request(struct request *req)
2506 blk_dequeue_request(req);
2509 * We are now handing the request to the hardware, initialize
2510 * resid_len to full count and add the timeout handler.
2512 req->resid_len = blk_rq_bytes(req);
2513 if (unlikely(blk_bidi_rq(req)))
2514 req->next_rq->resid_len = blk_rq_bytes(req->next_rq);
2516 BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
2519 EXPORT_SYMBOL(blk_start_request);
2522 * blk_fetch_request - fetch a request from a request queue
2523 * @q: request queue to fetch a request from
2526 * Return the request at the top of @q. The request is started on
2527 * return and LLD can start processing it immediately.
2530 * Pointer to the request at the top of @q if available. Null
2534 * queue_lock must be held.
2536 struct request *blk_fetch_request(struct request_queue *q)
2540 rq = blk_peek_request(q);
2542 blk_start_request(rq);
2545 EXPORT_SYMBOL(blk_fetch_request);
2548 * blk_update_request - Special helper function for request stacking drivers
2549 * @req: the request being processed
2550 * @error: %0 for success, < %0 for error
2551 * @nr_bytes: number of bytes to complete @req
2554 * Ends I/O on a number of bytes attached to @req, but doesn't complete
2555 * the request structure even if @req doesn't have leftover.
2556 * If @req has leftover, sets it up for the next range of segments.
2558 * This special helper function is only for request stacking drivers
2559 * (e.g. request-based dm) so that they can handle partial completion.
2560 * Actual device drivers should use blk_end_request instead.
2562 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
2563 * %false return from this function.
2566 * %false - this request doesn't have any more data
2567 * %true - this request has more data
2569 bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
2573 trace_block_rq_complete(req->q, req, nr_bytes);
2579 * For fs requests, rq is just carrier of independent bio's
2580 * and each partial completion should be handled separately.
2581 * Reset per-request error on each partial completion.
2583 * TODO: tj: This is too subtle. It would be better to let
2584 * low level drivers do what they see fit.
2586 if (req->cmd_type == REQ_TYPE_FS)
2589 if (error && req->cmd_type == REQ_TYPE_FS &&
2590 !(req->cmd_flags & REQ_QUIET)) {
2595 error_type = "recoverable transport";
2598 error_type = "critical target";
2601 error_type = "critical nexus";
2604 error_type = "timeout";
2607 error_type = "critical space allocation";
2610 error_type = "critical medium";
2617 printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n",
2618 __func__, error_type, req->rq_disk ?
2619 req->rq_disk->disk_name : "?",
2620 (unsigned long long)blk_rq_pos(req));
2624 blk_account_io_completion(req, nr_bytes);
2628 struct bio *bio = req->bio;
2629 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);
2631 if (bio_bytes == bio->bi_iter.bi_size)
2632 req->bio = bio->bi_next;
2634 req_bio_endio(req, bio, bio_bytes, error);
2636 total_bytes += bio_bytes;
2637 nr_bytes -= bio_bytes;
2648 * Reset counters so that the request stacking driver
2649 * can find how many bytes remain in the request
2652 req->__data_len = 0;
2656 req->__data_len -= total_bytes;
2658 /* update sector only for requests with clear definition of sector */
2659 if (req->cmd_type == REQ_TYPE_FS)
2660 req->__sector += total_bytes >> 9;
2662 /* mixed attributes always follow the first bio */
2663 if (req->cmd_flags & REQ_MIXED_MERGE) {
2664 req->cmd_flags &= ~REQ_FAILFAST_MASK;
2665 req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK;
2669 * If total number of sectors is less than the first segment
2670 * size, something has gone terribly wrong.
2672 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
2673 blk_dump_rq_flags(req, "request botched");
2674 req->__data_len = blk_rq_cur_bytes(req);
2677 /* recalculate the number of segments */
2678 blk_recalc_rq_segments(req);
2682 EXPORT_SYMBOL_GPL(blk_update_request);
2684 static bool blk_update_bidi_request(struct request *rq, int error,
2685 unsigned int nr_bytes,
2686 unsigned int bidi_bytes)
2688 if (blk_update_request(rq, error, nr_bytes))
2691 /* Bidi request must be completed as a whole */
2692 if (unlikely(blk_bidi_rq(rq)) &&
2693 blk_update_request(rq->next_rq, error, bidi_bytes))
2696 if (blk_queue_add_random(rq->q))
2697 add_disk_randomness(rq->rq_disk);
2703 * blk_unprep_request - unprepare a request
2706 * This function makes a request ready for complete resubmission (or
2707 * completion). It happens only after all error handling is complete,
2708 * so represents the appropriate moment to deallocate any resources
2709 * that were allocated to the request in the prep_rq_fn. The queue
2710 * lock is held when calling this.
2712 void blk_unprep_request(struct request *req)
2714 struct request_queue *q = req->q;
2716 req->cmd_flags &= ~REQ_DONTPREP;
2717 if (q->unprep_rq_fn)
2718 q->unprep_rq_fn(q, req);
2720 EXPORT_SYMBOL_GPL(blk_unprep_request);
2723 * queue lock must be held
2725 void blk_finish_request(struct request *req, int error)
2727 if (req->cmd_flags & REQ_QUEUED)
2728 blk_queue_end_tag(req->q, req);
2730 BUG_ON(blk_queued_rq(req));
2732 if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS)
2733 laptop_io_completion(&req->q->backing_dev_info);
2735 blk_delete_timer(req);
2737 if (req->cmd_flags & REQ_DONTPREP)
2738 blk_unprep_request(req);
2740 blk_account_io_done(req);
2743 req->end_io(req, error);
2745 if (blk_bidi_rq(req))
2746 __blk_put_request(req->next_rq->q, req->next_rq);
2748 __blk_put_request(req->q, req);
2751 EXPORT_SYMBOL(blk_finish_request);
2754 * blk_end_bidi_request - Complete a bidi request
2755 * @rq: the request to complete
2756 * @error: %0 for success, < %0 for error
2757 * @nr_bytes: number of bytes to complete @rq
2758 * @bidi_bytes: number of bytes to complete @rq->next_rq
2761 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2762 * Drivers that supports bidi can safely call this member for any
2763 * type of request, bidi or uni. In the later case @bidi_bytes is
2767 * %false - we are done with this request
2768 * %true - still buffers pending for this request
2770 static bool blk_end_bidi_request(struct request *rq, int error,
2771 unsigned int nr_bytes, unsigned int bidi_bytes)
2773 struct request_queue *q = rq->q;
2774 unsigned long flags;
2776 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2779 spin_lock_irqsave(q->queue_lock, flags);
2780 blk_finish_request(rq, error);
2781 spin_unlock_irqrestore(q->queue_lock, flags);
2787 * __blk_end_bidi_request - Complete a bidi request with queue lock held
2788 * @rq: the request to complete
2789 * @error: %0 for success, < %0 for error
2790 * @nr_bytes: number of bytes to complete @rq
2791 * @bidi_bytes: number of bytes to complete @rq->next_rq
2794 * Identical to blk_end_bidi_request() except that queue lock is
2795 * assumed to be locked on entry and remains so on return.
2798 * %false - we are done with this request
2799 * %true - still buffers pending for this request
2801 bool __blk_end_bidi_request(struct request *rq, int error,
2802 unsigned int nr_bytes, unsigned int bidi_bytes)
2804 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2807 blk_finish_request(rq, error);
2813 * blk_end_request - Helper function for drivers to complete the request.
2814 * @rq: the request being processed
2815 * @error: %0 for success, < %0 for error
2816 * @nr_bytes: number of bytes to complete
2819 * Ends I/O on a number of bytes attached to @rq.
2820 * If @rq has leftover, sets it up for the next range of segments.
2823 * %false - we are done with this request
2824 * %true - still buffers pending for this request
2826 bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
2828 return blk_end_bidi_request(rq, error, nr_bytes, 0);
2830 EXPORT_SYMBOL(blk_end_request);
2833 * blk_end_request_all - Helper function for drives to finish the request.
2834 * @rq: the request to finish
2835 * @error: %0 for success, < %0 for error
2838 * Completely finish @rq.
2840 void blk_end_request_all(struct request *rq, int error)
2843 unsigned int bidi_bytes = 0;
2845 if (unlikely(blk_bidi_rq(rq)))
2846 bidi_bytes = blk_rq_bytes(rq->next_rq);
2848 pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2851 EXPORT_SYMBOL(blk_end_request_all);
2854 * blk_end_request_cur - Helper function to finish the current request chunk.
2855 * @rq: the request to finish the current chunk for
2856 * @error: %0 for success, < %0 for error
2859 * Complete the current consecutively mapped chunk from @rq.
2862 * %false - we are done with this request
2863 * %true - still buffers pending for this request
2865 bool blk_end_request_cur(struct request *rq, int error)
2867 return blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2869 EXPORT_SYMBOL(blk_end_request_cur);
2872 * blk_end_request_err - Finish a request till the next failure boundary.
2873 * @rq: the request to finish till the next failure boundary for
2874 * @error: must be negative errno
2877 * Complete @rq till the next failure boundary.
2880 * %false - we are done with this request
2881 * %true - still buffers pending for this request
2883 bool blk_end_request_err(struct request *rq, int error)
2885 WARN_ON(error >= 0);
2886 return blk_end_request(rq, error, blk_rq_err_bytes(rq));
2888 EXPORT_SYMBOL_GPL(blk_end_request_err);
2891 * __blk_end_request - Helper function for drivers to complete the request.
2892 * @rq: the request being processed
2893 * @error: %0 for success, < %0 for error
2894 * @nr_bytes: number of bytes to complete
2897 * Must be called with queue lock held unlike blk_end_request().
2900 * %false - we are done with this request
2901 * %true - still buffers pending for this request
2903 bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
2905 return __blk_end_bidi_request(rq, error, nr_bytes, 0);
2907 EXPORT_SYMBOL(__blk_end_request);
2910 * __blk_end_request_all - Helper function for drives to finish the request.
2911 * @rq: the request to finish
2912 * @error: %0 for success, < %0 for error
2915 * Completely finish @rq. Must be called with queue lock held.
2917 void __blk_end_request_all(struct request *rq, int error)
2920 unsigned int bidi_bytes = 0;
2922 if (unlikely(blk_bidi_rq(rq)))
2923 bidi_bytes = blk_rq_bytes(rq->next_rq);
2925 pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2928 EXPORT_SYMBOL(__blk_end_request_all);
2931 * __blk_end_request_cur - Helper function to finish the current request chunk.
2932 * @rq: the request to finish the current chunk for
2933 * @error: %0 for success, < %0 for error
2936 * Complete the current consecutively mapped chunk from @rq. Must
2937 * be called with queue lock held.
2940 * %false - we are done with this request
2941 * %true - still buffers pending for this request
2943 bool __blk_end_request_cur(struct request *rq, int error)
2945 return __blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2947 EXPORT_SYMBOL(__blk_end_request_cur);
2950 * __blk_end_request_err - Finish a request till the next failure boundary.
2951 * @rq: the request to finish till the next failure boundary for
2952 * @error: must be negative errno
2955 * Complete @rq till the next failure boundary. Must be called
2956 * with queue lock held.
2959 * %false - we are done with this request
2960 * %true - still buffers pending for this request
2962 bool __blk_end_request_err(struct request *rq, int error)
2964 WARN_ON(error >= 0);
2965 return __blk_end_request(rq, error, blk_rq_err_bytes(rq));
2967 EXPORT_SYMBOL_GPL(__blk_end_request_err);
2969 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
2972 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */
2973 rq->cmd_flags |= bio->bi_rw & REQ_WRITE;
2975 if (bio_has_data(bio))
2976 rq->nr_phys_segments = bio_phys_segments(q, bio);
2978 rq->__data_len = bio->bi_iter.bi_size;
2979 rq->bio = rq->biotail = bio;
2982 rq->rq_disk = bio->bi_bdev->bd_disk;
2985 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
2987 * rq_flush_dcache_pages - Helper function to flush all pages in a request
2988 * @rq: the request to be flushed
2991 * Flush all pages in @rq.
2993 void rq_flush_dcache_pages(struct request *rq)
2995 struct req_iterator iter;
2996 struct bio_vec bvec;
2998 rq_for_each_segment(bvec, rq, iter)
2999 flush_dcache_page(bvec.bv_page);
3001 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
3005 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
3006 * @q : the queue of the device being checked
3009 * Check if underlying low-level drivers of a device are busy.
3010 * If the drivers want to export their busy state, they must set own
3011 * exporting function using blk_queue_lld_busy() first.
3013 * Basically, this function is used only by request stacking drivers
3014 * to stop dispatching requests to underlying devices when underlying
3015 * devices are busy. This behavior helps more I/O merging on the queue
3016 * of the request stacking driver and prevents I/O throughput regression
3017 * on burst I/O load.
3020 * 0 - Not busy (The request stacking driver should dispatch request)
3021 * 1 - Busy (The request stacking driver should stop dispatching request)
3023 int blk_lld_busy(struct request_queue *q)
3026 return q->lld_busy_fn(q);
3030 EXPORT_SYMBOL_GPL(blk_lld_busy);
3033 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
3034 * @rq: the clone request to be cleaned up
3037 * Free all bios in @rq for a cloned request.
3039 void blk_rq_unprep_clone(struct request *rq)
3043 while ((bio = rq->bio) != NULL) {
3044 rq->bio = bio->bi_next;
3049 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
3052 * Copy attributes of the original request to the clone request.
3053 * The actual data parts (e.g. ->cmd, ->sense) are not copied.
3055 static void __blk_rq_prep_clone(struct request *dst, struct request *src)
3057 dst->cpu = src->cpu;
3058 dst->cmd_flags |= (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE;
3059 dst->cmd_type = src->cmd_type;
3060 dst->__sector = blk_rq_pos(src);
3061 dst->__data_len = blk_rq_bytes(src);
3062 dst->nr_phys_segments = src->nr_phys_segments;
3063 dst->ioprio = src->ioprio;
3064 dst->extra_len = src->extra_len;
3068 * blk_rq_prep_clone - Helper function to setup clone request
3069 * @rq: the request to be setup
3070 * @rq_src: original request to be cloned
3071 * @bs: bio_set that bios for clone are allocated from
3072 * @gfp_mask: memory allocation mask for bio
3073 * @bio_ctr: setup function to be called for each clone bio.
3074 * Returns %0 for success, non %0 for failure.
3075 * @data: private data to be passed to @bio_ctr
3078 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
3079 * The actual data parts of @rq_src (e.g. ->cmd, ->sense)
3080 * are not copied, and copying such parts is the caller's responsibility.
3081 * Also, pages which the original bios are pointing to are not copied
3082 * and the cloned bios just point same pages.
3083 * So cloned bios must be completed before original bios, which means
3084 * the caller must complete @rq before @rq_src.
3086 int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
3087 struct bio_set *bs, gfp_t gfp_mask,
3088 int (*bio_ctr)(struct bio *, struct bio *, void *),
3091 struct bio *bio, *bio_src;
3096 __rq_for_each_bio(bio_src, rq_src) {
3097 bio = bio_clone_fast(bio_src, gfp_mask, bs);
3101 if (bio_ctr && bio_ctr(bio, bio_src, data))
3105 rq->biotail->bi_next = bio;
3108 rq->bio = rq->biotail = bio;
3111 __blk_rq_prep_clone(rq, rq_src);
3118 blk_rq_unprep_clone(rq);
3122 EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
3124 int kblockd_schedule_work(struct work_struct *work)
3126 return queue_work(kblockd_workqueue, work);
3128 EXPORT_SYMBOL(kblockd_schedule_work);
3130 int kblockd_schedule_delayed_work(struct delayed_work *dwork,
3131 unsigned long delay)
3133 return queue_delayed_work(kblockd_workqueue, dwork, delay);
3135 EXPORT_SYMBOL(kblockd_schedule_delayed_work);
3137 int kblockd_schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
3138 unsigned long delay)
3140 return queue_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
3142 EXPORT_SYMBOL(kblockd_schedule_delayed_work_on);
3145 * blk_start_plug - initialize blk_plug and track it inside the task_struct
3146 * @plug: The &struct blk_plug that needs to be initialized
3149 * Tracking blk_plug inside the task_struct will help with auto-flushing the
3150 * pending I/O should the task end up blocking between blk_start_plug() and
3151 * blk_finish_plug(). This is important from a performance perspective, but
3152 * also ensures that we don't deadlock. For instance, if the task is blocking
3153 * for a memory allocation, memory reclaim could end up wanting to free a
3154 * page belonging to that request that is currently residing in our private
3155 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
3156 * this kind of deadlock.
3158 void blk_start_plug(struct blk_plug *plug)
3160 struct task_struct *tsk = current;
3163 * If this is a nested plug, don't actually assign it.
3168 INIT_LIST_HEAD(&plug->list);
3169 INIT_LIST_HEAD(&plug->mq_list);
3170 INIT_LIST_HEAD(&plug->cb_list);
3172 * Store ordering should not be needed here, since a potential
3173 * preempt will imply a full memory barrier
3177 EXPORT_SYMBOL(blk_start_plug);
3179 static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
3181 struct request *rqa = container_of(a, struct request, queuelist);
3182 struct request *rqb = container_of(b, struct request, queuelist);
3184 return !(rqa->q < rqb->q ||
3185 (rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb)));
3189 * If 'from_schedule' is true, then postpone the dispatch of requests
3190 * until a safe kblockd context. We due this to avoid accidental big
3191 * additional stack usage in driver dispatch, in places where the originally
3192 * plugger did not intend it.
3194 static void queue_unplugged(struct request_queue *q, unsigned int depth,
3196 __releases(q->queue_lock)
3198 trace_block_unplug(q, depth, !from_schedule);
3201 blk_run_queue_async(q);
3204 spin_unlock_irq(q->queue_lock);
3207 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
3209 LIST_HEAD(callbacks);
3211 while (!list_empty(&plug->cb_list)) {
3212 list_splice_init(&plug->cb_list, &callbacks);
3214 while (!list_empty(&callbacks)) {
3215 struct blk_plug_cb *cb = list_first_entry(&callbacks,
3218 list_del(&cb->list);
3219 cb->callback(cb, from_schedule);
3224 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
3227 struct blk_plug *plug = current->plug;
3228 struct blk_plug_cb *cb;
3233 list_for_each_entry(cb, &plug->cb_list, list)
3234 if (cb->callback == unplug && cb->data == data)
3237 /* Not currently on the callback list */
3238 BUG_ON(size < sizeof(*cb));
3239 cb = kzalloc(size, GFP_ATOMIC);
3242 cb->callback = unplug;
3243 list_add(&cb->list, &plug->cb_list);
3247 EXPORT_SYMBOL(blk_check_plugged);
3249 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
3251 struct request_queue *q;
3256 flush_plug_callbacks(plug, from_schedule);
3258 if (!list_empty(&plug->mq_list))
3259 blk_mq_flush_plug_list(plug, from_schedule);
3261 if (list_empty(&plug->list))
3264 list_splice_init(&plug->list, &list);
3266 list_sort(NULL, &list, plug_rq_cmp);
3271 while (!list_empty(&list)) {
3272 rq = list_entry_rq(list.next);
3273 list_del_init(&rq->queuelist);
3277 * This drops the queue lock
3280 queue_unplugged(q, depth, from_schedule);
3283 spin_lock_irq(q->queue_lock);
3287 * Short-circuit if @q is dead
3289 if (unlikely(blk_queue_dying(q))) {
3290 __blk_end_request_all(rq, -ENODEV);
3295 * rq is already accounted, so use raw insert
3297 if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA))
3298 __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
3300 __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);
3306 * This drops the queue lock
3309 queue_unplugged(q, depth, from_schedule);
3312 void blk_finish_plug(struct blk_plug *plug)
3314 if (plug != current->plug)
3316 blk_flush_plug_list(plug, false);
3318 current->plug = NULL;
3320 EXPORT_SYMBOL(blk_finish_plug);
3322 bool blk_poll(struct request_queue *q, blk_qc_t cookie)
3324 struct blk_plug *plug;
3327 if (!q->mq_ops || !q->mq_ops->poll || !blk_qc_t_valid(cookie) ||
3328 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
3331 plug = current->plug;
3333 blk_flush_plug_list(plug, false);
3335 state = current->state;
3336 while (!need_resched()) {
3337 unsigned int queue_num = blk_qc_t_to_queue_num(cookie);
3338 struct blk_mq_hw_ctx *hctx = q->queue_hw_ctx[queue_num];
3341 hctx->poll_invoked++;
3343 ret = q->mq_ops->poll(hctx, blk_qc_t_to_tag(cookie));
3345 hctx->poll_success++;
3346 set_current_state(TASK_RUNNING);
3350 if (signal_pending_state(state, current))
3351 set_current_state(TASK_RUNNING);
3353 if (current->state == TASK_RUNNING)
3365 * blk_pm_runtime_init - Block layer runtime PM initialization routine
3366 * @q: the queue of the device
3367 * @dev: the device the queue belongs to
3370 * Initialize runtime-PM-related fields for @q and start auto suspend for
3371 * @dev. Drivers that want to take advantage of request-based runtime PM
3372 * should call this function after @dev has been initialized, and its
3373 * request queue @q has been allocated, and runtime PM for it can not happen
3374 * yet(either due to disabled/forbidden or its usage_count > 0). In most
3375 * cases, driver should call this function before any I/O has taken place.
3377 * This function takes care of setting up using auto suspend for the device,
3378 * the autosuspend delay is set to -1 to make runtime suspend impossible
3379 * until an updated value is either set by user or by driver. Drivers do
3380 * not need to touch other autosuspend settings.
3382 * The block layer runtime PM is request based, so only works for drivers
3383 * that use request as their IO unit instead of those directly use bio's.
3385 void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
3388 q->rpm_status = RPM_ACTIVE;
3389 pm_runtime_set_autosuspend_delay(q->dev, -1);
3390 pm_runtime_use_autosuspend(q->dev);
3392 EXPORT_SYMBOL(blk_pm_runtime_init);
3395 * blk_pre_runtime_suspend - Pre runtime suspend check
3396 * @q: the queue of the device
3399 * This function will check if runtime suspend is allowed for the device
3400 * by examining if there are any requests pending in the queue. If there
3401 * are requests pending, the device can not be runtime suspended; otherwise,
3402 * the queue's status will be updated to SUSPENDING and the driver can
3403 * proceed to suspend the device.
3405 * For the not allowed case, we mark last busy for the device so that
3406 * runtime PM core will try to autosuspend it some time later.
3408 * This function should be called near the start of the device's
3409 * runtime_suspend callback.
3412 * 0 - OK to runtime suspend the device
3413 * -EBUSY - Device should not be runtime suspended
3415 int blk_pre_runtime_suspend(struct request_queue *q)
3422 spin_lock_irq(q->queue_lock);
3423 if (q->nr_pending) {
3425 pm_runtime_mark_last_busy(q->dev);
3427 q->rpm_status = RPM_SUSPENDING;
3429 spin_unlock_irq(q->queue_lock);
3432 EXPORT_SYMBOL(blk_pre_runtime_suspend);
3435 * blk_post_runtime_suspend - Post runtime suspend processing
3436 * @q: the queue of the device
3437 * @err: return value of the device's runtime_suspend function
3440 * Update the queue's runtime status according to the return value of the
3441 * device's runtime suspend function and mark last busy for the device so
3442 * that PM core will try to auto suspend the device at a later time.
3444 * This function should be called near the end of the device's
3445 * runtime_suspend callback.
3447 void blk_post_runtime_suspend(struct request_queue *q, int err)
3452 spin_lock_irq(q->queue_lock);
3454 q->rpm_status = RPM_SUSPENDED;
3456 q->rpm_status = RPM_ACTIVE;
3457 pm_runtime_mark_last_busy(q->dev);
3459 spin_unlock_irq(q->queue_lock);
3461 EXPORT_SYMBOL(blk_post_runtime_suspend);
3464 * blk_pre_runtime_resume - Pre runtime resume processing
3465 * @q: the queue of the device
3468 * Update the queue's runtime status to RESUMING in preparation for the
3469 * runtime resume of the device.
3471 * This function should be called near the start of the device's
3472 * runtime_resume callback.
3474 void blk_pre_runtime_resume(struct request_queue *q)
3479 spin_lock_irq(q->queue_lock);
3480 q->rpm_status = RPM_RESUMING;
3481 spin_unlock_irq(q->queue_lock);
3483 EXPORT_SYMBOL(blk_pre_runtime_resume);
3486 * blk_post_runtime_resume - Post runtime resume processing
3487 * @q: the queue of the device
3488 * @err: return value of the device's runtime_resume function
3491 * Update the queue's runtime status according to the return value of the
3492 * device's runtime_resume function. If it is successfully resumed, process
3493 * the requests that are queued into the device's queue when it is resuming
3494 * and then mark last busy and initiate autosuspend for it.
3496 * This function should be called near the end of the device's
3497 * runtime_resume callback.
3499 void blk_post_runtime_resume(struct request_queue *q, int err)
3504 spin_lock_irq(q->queue_lock);
3506 q->rpm_status = RPM_ACTIVE;
3508 pm_runtime_mark_last_busy(q->dev);
3509 pm_request_autosuspend(q->dev);
3511 q->rpm_status = RPM_SUSPENDED;
3513 spin_unlock_irq(q->queue_lock);
3515 EXPORT_SYMBOL(blk_post_runtime_resume);
3518 int __init blk_dev_init(void)
3520 BUILD_BUG_ON(__REQ_NR_BITS > 8 *
3521 FIELD_SIZEOF(struct request, cmd_flags));
3523 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
3524 kblockd_workqueue = alloc_workqueue("kblockd",
3525 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
3526 if (!kblockd_workqueue)
3527 panic("Failed to create kblockd\n");
3529 request_cachep = kmem_cache_create("blkdev_requests",
3530 sizeof(struct request), 0, SLAB_PANIC, NULL);
3532 blk_requestq_cachep = kmem_cache_create("blkdev_queue",
3533 sizeof(struct request_queue), 0, SLAB_PANIC, NULL);