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
;
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_async - asynchronously restart a previously stopped queue
211 * @q: The &struct request_queue in question
214 * blk_start_queue_async() will clear the stop flag on the queue, and
215 * ensure that the request_fn for the queue is run from an async
218 void blk_start_queue_async(struct request_queue
*q
)
220 queue_flag_clear(QUEUE_FLAG_STOPPED
, q
);
221 blk_run_queue_async(q
);
223 EXPORT_SYMBOL(blk_start_queue_async
);
226 * blk_start_queue - restart a previously stopped queue
227 * @q: The &struct request_queue in question
230 * blk_start_queue() will clear the stop flag on the queue, and call
231 * the request_fn for the queue if it was in a stopped state when
232 * entered. Also see blk_stop_queue(). Queue lock must be held.
234 void blk_start_queue(struct request_queue
*q
)
236 WARN_ON(!irqs_disabled());
238 queue_flag_clear(QUEUE_FLAG_STOPPED
, q
);
241 EXPORT_SYMBOL(blk_start_queue
);
244 * blk_stop_queue - stop a queue
245 * @q: The &struct request_queue in question
248 * The Linux block layer assumes that a block driver will consume all
249 * entries on the request queue when the request_fn strategy is called.
250 * Often this will not happen, because of hardware limitations (queue
251 * depth settings). If a device driver gets a 'queue full' response,
252 * or if it simply chooses not to queue more I/O at one point, it can
253 * call this function to prevent the request_fn from being called until
254 * the driver has signalled it's ready to go again. This happens by calling
255 * blk_start_queue() to restart queue operations. Queue lock must be held.
257 void blk_stop_queue(struct request_queue
*q
)
259 cancel_delayed_work(&q
->delay_work
);
260 queue_flag_set(QUEUE_FLAG_STOPPED
, q
);
262 EXPORT_SYMBOL(blk_stop_queue
);
265 * blk_sync_queue - cancel any pending callbacks on a queue
269 * The block layer may perform asynchronous callback activity
270 * on a queue, such as calling the unplug function after a timeout.
271 * A block device may call blk_sync_queue to ensure that any
272 * such activity is cancelled, thus allowing it to release resources
273 * that the callbacks might use. The caller must already have made sure
274 * that its ->make_request_fn will not re-add plugging prior to calling
277 * This function does not cancel any asynchronous activity arising
278 * out of elevator or throttling code. That would require elevator_exit()
279 * and blkcg_exit_queue() to be called with queue lock initialized.
282 void blk_sync_queue(struct request_queue
*q
)
284 del_timer_sync(&q
->timeout
);
287 struct blk_mq_hw_ctx
*hctx
;
290 queue_for_each_hw_ctx(q
, hctx
, i
) {
291 cancel_delayed_work_sync(&hctx
->run_work
);
292 cancel_delayed_work_sync(&hctx
->delay_work
);
295 cancel_delayed_work_sync(&q
->delay_work
);
298 EXPORT_SYMBOL(blk_sync_queue
);
301 * __blk_run_queue_uncond - run a queue whether or not it has been stopped
302 * @q: The queue to run
305 * Invoke request handling on a queue if there are any pending requests.
306 * May be used to restart request handling after a request has completed.
307 * This variant runs the queue whether or not the queue has been
308 * stopped. Must be called with the queue lock held and interrupts
309 * disabled. See also @blk_run_queue.
311 inline void __blk_run_queue_uncond(struct request_queue
*q
)
313 if (unlikely(blk_queue_dead(q
)))
317 * Some request_fn implementations, e.g. scsi_request_fn(), unlock
318 * the queue lock internally. As a result multiple threads may be
319 * running such a request function concurrently. Keep track of the
320 * number of active request_fn invocations such that blk_drain_queue()
321 * can wait until all these request_fn calls have finished.
323 q
->request_fn_active
++;
325 q
->request_fn_active
--;
327 EXPORT_SYMBOL_GPL(__blk_run_queue_uncond
);
330 * __blk_run_queue - run a single device queue
331 * @q: The queue to run
334 * See @blk_run_queue. This variant must be called with the queue lock
335 * held and interrupts disabled.
337 void __blk_run_queue(struct request_queue
*q
)
339 if (unlikely(blk_queue_stopped(q
)))
342 __blk_run_queue_uncond(q
);
344 EXPORT_SYMBOL(__blk_run_queue
);
347 * blk_run_queue_async - run a single device queue in workqueue context
348 * @q: The queue to run
351 * Tells kblockd to perform the equivalent of @blk_run_queue on behalf
352 * of us. The caller must hold the queue lock.
354 void blk_run_queue_async(struct request_queue
*q
)
356 if (likely(!blk_queue_stopped(q
) && !blk_queue_dead(q
)))
357 mod_delayed_work(kblockd_workqueue
, &q
->delay_work
, 0);
359 EXPORT_SYMBOL(blk_run_queue_async
);
362 * blk_run_queue - run a single device queue
363 * @q: The queue to run
366 * Invoke request handling on this queue, if it has pending work to do.
367 * May be used to restart queueing when a request has completed.
369 void blk_run_queue(struct request_queue
*q
)
373 spin_lock_irqsave(q
->queue_lock
, flags
);
375 spin_unlock_irqrestore(q
->queue_lock
, flags
);
377 EXPORT_SYMBOL(blk_run_queue
);
379 void blk_put_queue(struct request_queue
*q
)
381 kobject_put(&q
->kobj
);
383 EXPORT_SYMBOL(blk_put_queue
);
386 * __blk_drain_queue - drain requests from request_queue
388 * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
390 * Drain requests from @q. If @drain_all is set, all requests are drained.
391 * If not, only ELVPRIV requests are drained. The caller is responsible
392 * for ensuring that no new requests which need to be drained are queued.
394 static void __blk_drain_queue(struct request_queue
*q
, bool drain_all
)
395 __releases(q
->queue_lock
)
396 __acquires(q
->queue_lock
)
400 lockdep_assert_held(q
->queue_lock
);
406 * The caller might be trying to drain @q before its
407 * elevator is initialized.
410 elv_drain_elevator(q
);
412 blkcg_drain_queue(q
);
415 * This function might be called on a queue which failed
416 * driver init after queue creation or is not yet fully
417 * active yet. Some drivers (e.g. fd and loop) get unhappy
418 * in such cases. Kick queue iff dispatch queue has
419 * something on it and @q has request_fn set.
421 if (!list_empty(&q
->queue_head
) && q
->request_fn
)
424 drain
|= q
->nr_rqs_elvpriv
;
425 drain
|= q
->request_fn_active
;
428 * Unfortunately, requests are queued at and tracked from
429 * multiple places and there's no single counter which can
430 * be drained. Check all the queues and counters.
433 struct blk_flush_queue
*fq
= blk_get_flush_queue(q
, NULL
);
434 drain
|= !list_empty(&q
->queue_head
);
435 for (i
= 0; i
< 2; i
++) {
436 drain
|= q
->nr_rqs
[i
];
437 drain
|= q
->in_flight
[i
];
439 drain
|= !list_empty(&fq
->flush_queue
[i
]);
446 spin_unlock_irq(q
->queue_lock
);
450 spin_lock_irq(q
->queue_lock
);
454 * With queue marked dead, any woken up waiter will fail the
455 * allocation path, so the wakeup chaining is lost and we're
456 * left with hung waiters. We need to wake up those waiters.
459 struct request_list
*rl
;
461 blk_queue_for_each_rl(rl
, q
)
462 for (i
= 0; i
< ARRAY_SIZE(rl
->wait
); i
++)
463 wake_up_all(&rl
->wait
[i
]);
468 * blk_queue_bypass_start - enter queue bypass mode
469 * @q: queue of interest
471 * In bypass mode, only the dispatch FIFO queue of @q is used. This
472 * function makes @q enter bypass mode and drains all requests which were
473 * throttled or issued before. On return, it's guaranteed that no request
474 * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
475 * inside queue or RCU read lock.
477 void blk_queue_bypass_start(struct request_queue
*q
)
479 spin_lock_irq(q
->queue_lock
);
481 queue_flag_set(QUEUE_FLAG_BYPASS
, q
);
482 spin_unlock_irq(q
->queue_lock
);
485 * Queues start drained. Skip actual draining till init is
486 * complete. This avoids lenghty delays during queue init which
487 * can happen many times during boot.
489 if (blk_queue_init_done(q
)) {
490 spin_lock_irq(q
->queue_lock
);
491 __blk_drain_queue(q
, false);
492 spin_unlock_irq(q
->queue_lock
);
494 /* ensure blk_queue_bypass() is %true inside RCU read lock */
498 EXPORT_SYMBOL_GPL(blk_queue_bypass_start
);
501 * blk_queue_bypass_end - leave queue bypass mode
502 * @q: queue of interest
504 * Leave bypass mode and restore the normal queueing behavior.
506 void blk_queue_bypass_end(struct request_queue
*q
)
508 spin_lock_irq(q
->queue_lock
);
509 if (!--q
->bypass_depth
)
510 queue_flag_clear(QUEUE_FLAG_BYPASS
, q
);
511 WARN_ON_ONCE(q
->bypass_depth
< 0);
512 spin_unlock_irq(q
->queue_lock
);
514 EXPORT_SYMBOL_GPL(blk_queue_bypass_end
);
516 void blk_set_queue_dying(struct request_queue
*q
)
518 queue_flag_set_unlocked(QUEUE_FLAG_DYING
, q
);
521 blk_mq_wake_waiters(q
);
523 struct request_list
*rl
;
525 blk_queue_for_each_rl(rl
, q
) {
527 wake_up(&rl
->wait
[BLK_RW_SYNC
]);
528 wake_up(&rl
->wait
[BLK_RW_ASYNC
]);
533 EXPORT_SYMBOL_GPL(blk_set_queue_dying
);
536 * blk_cleanup_queue - shutdown a request queue
537 * @q: request queue to shutdown
539 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
540 * put it. All future requests will be failed immediately with -ENODEV.
542 void blk_cleanup_queue(struct request_queue
*q
)
544 spinlock_t
*lock
= q
->queue_lock
;
546 /* mark @q DYING, no new request or merges will be allowed afterwards */
547 mutex_lock(&q
->sysfs_lock
);
548 blk_set_queue_dying(q
);
552 * A dying queue is permanently in bypass mode till released. Note
553 * that, unlike blk_queue_bypass_start(), we aren't performing
554 * synchronize_rcu() after entering bypass mode to avoid the delay
555 * as some drivers create and destroy a lot of queues while
556 * probing. This is still safe because blk_release_queue() will be
557 * called only after the queue refcnt drops to zero and nothing,
558 * RCU or not, would be traversing the queue by then.
561 queue_flag_set(QUEUE_FLAG_BYPASS
, q
);
563 queue_flag_set(QUEUE_FLAG_NOMERGES
, q
);
564 queue_flag_set(QUEUE_FLAG_NOXMERGES
, q
);
565 queue_flag_set(QUEUE_FLAG_DYING
, q
);
566 spin_unlock_irq(lock
);
567 mutex_unlock(&q
->sysfs_lock
);
570 * Drain all requests queued before DYING marking. Set DEAD flag to
571 * prevent that q->request_fn() gets invoked after draining finished.
576 __blk_drain_queue(q
, true);
577 queue_flag_set(QUEUE_FLAG_DEAD
, q
);
578 spin_unlock_irq(lock
);
580 /* for synchronous bio-based driver finish in-flight integrity i/o */
581 blk_flush_integrity();
583 /* @q won't process any more request, flush async actions */
584 del_timer_sync(&q
->backing_dev_info
.laptop_mode_wb_timer
);
588 blk_mq_free_queue(q
);
589 percpu_ref_exit(&q
->q_usage_counter
);
592 if (q
->queue_lock
!= &q
->__queue_lock
)
593 q
->queue_lock
= &q
->__queue_lock
;
594 spin_unlock_irq(lock
);
596 bdi_unregister(&q
->backing_dev_info
);
598 /* @q is and will stay empty, shutdown and put */
601 EXPORT_SYMBOL(blk_cleanup_queue
);
603 /* Allocate memory local to the request queue */
604 static void *alloc_request_struct(gfp_t gfp_mask
, void *data
)
606 int nid
= (int)(long)data
;
607 return kmem_cache_alloc_node(request_cachep
, gfp_mask
, nid
);
610 static void free_request_struct(void *element
, void *unused
)
612 kmem_cache_free(request_cachep
, element
);
615 int blk_init_rl(struct request_list
*rl
, struct request_queue
*q
,
618 if (unlikely(rl
->rq_pool
))
622 rl
->count
[BLK_RW_SYNC
] = rl
->count
[BLK_RW_ASYNC
] = 0;
623 rl
->starved
[BLK_RW_SYNC
] = rl
->starved
[BLK_RW_ASYNC
] = 0;
624 init_waitqueue_head(&rl
->wait
[BLK_RW_SYNC
]);
625 init_waitqueue_head(&rl
->wait
[BLK_RW_ASYNC
]);
627 rl
->rq_pool
= mempool_create_node(BLKDEV_MIN_RQ
, alloc_request_struct
,
629 (void *)(long)q
->node
, gfp_mask
,
637 void blk_exit_rl(struct request_list
*rl
)
640 mempool_destroy(rl
->rq_pool
);
643 struct request_queue
*blk_alloc_queue(gfp_t gfp_mask
)
645 return blk_alloc_queue_node(gfp_mask
, NUMA_NO_NODE
);
647 EXPORT_SYMBOL(blk_alloc_queue
);
649 int blk_queue_enter(struct request_queue
*q
, bool nowait
)
654 if (percpu_ref_tryget_live(&q
->q_usage_counter
))
660 ret
= wait_event_interruptible(q
->mq_freeze_wq
,
661 !atomic_read(&q
->mq_freeze_depth
) ||
663 if (blk_queue_dying(q
))
670 void blk_queue_exit(struct request_queue
*q
)
672 percpu_ref_put(&q
->q_usage_counter
);
675 static void blk_queue_usage_counter_release(struct percpu_ref
*ref
)
677 struct request_queue
*q
=
678 container_of(ref
, struct request_queue
, q_usage_counter
);
680 wake_up_all(&q
->mq_freeze_wq
);
683 static void blk_rq_timed_out_timer(unsigned long data
)
685 struct request_queue
*q
= (struct request_queue
*)data
;
687 kblockd_schedule_work(&q
->timeout_work
);
690 struct request_queue
*blk_alloc_queue_node(gfp_t gfp_mask
, int node_id
)
692 struct request_queue
*q
;
695 q
= kmem_cache_alloc_node(blk_requestq_cachep
,
696 gfp_mask
| __GFP_ZERO
, node_id
);
700 q
->id
= ida_simple_get(&blk_queue_ida
, 0, 0, gfp_mask
);
704 q
->bio_split
= bioset_create(BIO_POOL_SIZE
, 0);
708 q
->backing_dev_info
.ra_pages
=
709 (VM_MAX_READAHEAD
* 1024) / PAGE_SIZE
;
710 q
->backing_dev_info
.capabilities
= BDI_CAP_CGROUP_WRITEBACK
;
711 q
->backing_dev_info
.name
= "block";
714 err
= bdi_init(&q
->backing_dev_info
);
718 setup_timer(&q
->backing_dev_info
.laptop_mode_wb_timer
,
719 laptop_mode_timer_fn
, (unsigned long) q
);
720 setup_timer(&q
->timeout
, blk_rq_timed_out_timer
, (unsigned long) q
);
721 INIT_LIST_HEAD(&q
->queue_head
);
722 INIT_LIST_HEAD(&q
->timeout_list
);
723 INIT_LIST_HEAD(&q
->icq_list
);
724 #ifdef CONFIG_BLK_CGROUP
725 INIT_LIST_HEAD(&q
->blkg_list
);
727 INIT_DELAYED_WORK(&q
->delay_work
, blk_delay_work
);
729 kobject_init(&q
->kobj
, &blk_queue_ktype
);
731 mutex_init(&q
->sysfs_lock
);
732 spin_lock_init(&q
->__queue_lock
);
735 * By default initialize queue_lock to internal lock and driver can
736 * override it later if need be.
738 q
->queue_lock
= &q
->__queue_lock
;
741 * A queue starts its life with bypass turned on to avoid
742 * unnecessary bypass on/off overhead and nasty surprises during
743 * init. The initial bypass will be finished when the queue is
744 * registered by blk_register_queue().
747 __set_bit(QUEUE_FLAG_BYPASS
, &q
->queue_flags
);
749 init_waitqueue_head(&q
->mq_freeze_wq
);
752 * Init percpu_ref in atomic mode so that it's faster to shutdown.
753 * See blk_register_queue() for details.
755 if (percpu_ref_init(&q
->q_usage_counter
,
756 blk_queue_usage_counter_release
,
757 PERCPU_REF_INIT_ATOMIC
, GFP_KERNEL
))
760 if (blkcg_init_queue(q
))
766 percpu_ref_exit(&q
->q_usage_counter
);
768 bdi_destroy(&q
->backing_dev_info
);
770 bioset_free(q
->bio_split
);
772 ida_simple_remove(&blk_queue_ida
, q
->id
);
774 kmem_cache_free(blk_requestq_cachep
, q
);
777 EXPORT_SYMBOL(blk_alloc_queue_node
);
780 * blk_init_queue - prepare a request queue for use with a block device
781 * @rfn: The function to be called to process requests that have been
782 * placed on the queue.
783 * @lock: Request queue spin lock
786 * If a block device wishes to use the standard request handling procedures,
787 * which sorts requests and coalesces adjacent requests, then it must
788 * call blk_init_queue(). The function @rfn will be called when there
789 * are requests on the queue that need to be processed. If the device
790 * supports plugging, then @rfn may not be called immediately when requests
791 * are available on the queue, but may be called at some time later instead.
792 * Plugged queues are generally unplugged when a buffer belonging to one
793 * of the requests on the queue is needed, or due to memory pressure.
795 * @rfn is not required, or even expected, to remove all requests off the
796 * queue, but only as many as it can handle at a time. If it does leave
797 * requests on the queue, it is responsible for arranging that the requests
798 * get dealt with eventually.
800 * The queue spin lock must be held while manipulating the requests on the
801 * request queue; this lock will be taken also from interrupt context, so irq
802 * disabling is needed for it.
804 * Function returns a pointer to the initialized request queue, or %NULL if
808 * blk_init_queue() must be paired with a blk_cleanup_queue() call
809 * when the block device is deactivated (such as at module unload).
812 struct request_queue
*blk_init_queue(request_fn_proc
*rfn
, spinlock_t
*lock
)
814 return blk_init_queue_node(rfn
, lock
, NUMA_NO_NODE
);
816 EXPORT_SYMBOL(blk_init_queue
);
818 struct request_queue
*
819 blk_init_queue_node(request_fn_proc
*rfn
, spinlock_t
*lock
, int node_id
)
821 struct request_queue
*uninit_q
, *q
;
823 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, node_id
);
827 q
= blk_init_allocated_queue(uninit_q
, rfn
, lock
);
829 blk_cleanup_queue(uninit_q
);
833 EXPORT_SYMBOL(blk_init_queue_node
);
835 static blk_qc_t
blk_queue_bio(struct request_queue
*q
, struct bio
*bio
);
837 struct request_queue
*
838 blk_init_allocated_queue(struct request_queue
*q
, request_fn_proc
*rfn
,
844 q
->fq
= blk_alloc_flush_queue(q
, NUMA_NO_NODE
, 0);
848 if (blk_init_rl(&q
->root_rl
, q
, GFP_KERNEL
))
851 INIT_WORK(&q
->timeout_work
, blk_timeout_work
);
853 q
->prep_rq_fn
= NULL
;
854 q
->unprep_rq_fn
= NULL
;
855 q
->queue_flags
|= QUEUE_FLAG_DEFAULT
;
857 /* Override internal queue lock with supplied lock pointer */
859 q
->queue_lock
= lock
;
862 * This also sets hw/phys segments, boundary and size
864 blk_queue_make_request(q
, blk_queue_bio
);
866 q
->sg_reserved_size
= INT_MAX
;
868 /* Protect q->elevator from elevator_change */
869 mutex_lock(&q
->sysfs_lock
);
872 if (elevator_init(q
, NULL
)) {
873 mutex_unlock(&q
->sysfs_lock
);
877 mutex_unlock(&q
->sysfs_lock
);
882 blk_free_flush_queue(q
->fq
);
885 EXPORT_SYMBOL(blk_init_allocated_queue
);
887 bool blk_get_queue(struct request_queue
*q
)
889 if (likely(!blk_queue_dying(q
))) {
896 EXPORT_SYMBOL(blk_get_queue
);
898 static inline void blk_free_request(struct request_list
*rl
, struct request
*rq
)
900 if (rq
->cmd_flags
& REQ_ELVPRIV
) {
901 elv_put_request(rl
->q
, rq
);
903 put_io_context(rq
->elv
.icq
->ioc
);
906 mempool_free(rq
, rl
->rq_pool
);
910 * ioc_batching returns true if the ioc is a valid batching request and
911 * should be given priority access to a request.
913 static inline int ioc_batching(struct request_queue
*q
, struct io_context
*ioc
)
919 * Make sure the process is able to allocate at least 1 request
920 * even if the batch times out, otherwise we could theoretically
923 return ioc
->nr_batch_requests
== q
->nr_batching
||
924 (ioc
->nr_batch_requests
> 0
925 && time_before(jiffies
, ioc
->last_waited
+ BLK_BATCH_TIME
));
929 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
930 * will cause the process to be a "batcher" on all queues in the system. This
931 * is the behaviour we want though - once it gets a wakeup it should be given
934 static void ioc_set_batching(struct request_queue
*q
, struct io_context
*ioc
)
936 if (!ioc
|| ioc_batching(q
, ioc
))
939 ioc
->nr_batch_requests
= q
->nr_batching
;
940 ioc
->last_waited
= jiffies
;
943 static void __freed_request(struct request_list
*rl
, int sync
)
945 struct request_queue
*q
= rl
->q
;
947 if (rl
->count
[sync
] < queue_congestion_off_threshold(q
))
948 blk_clear_congested(rl
, sync
);
950 if (rl
->count
[sync
] + 1 <= q
->nr_requests
) {
951 if (waitqueue_active(&rl
->wait
[sync
]))
952 wake_up(&rl
->wait
[sync
]);
954 blk_clear_rl_full(rl
, sync
);
959 * A request has just been released. Account for it, update the full and
960 * congestion status, wake up any waiters. Called under q->queue_lock.
962 static void freed_request(struct request_list
*rl
, int op
, unsigned int flags
)
964 struct request_queue
*q
= rl
->q
;
965 int sync
= rw_is_sync(op
, flags
);
969 if (flags
& REQ_ELVPRIV
)
972 __freed_request(rl
, sync
);
974 if (unlikely(rl
->starved
[sync
^ 1]))
975 __freed_request(rl
, sync
^ 1);
978 int blk_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
980 struct request_list
*rl
;
981 int on_thresh
, off_thresh
;
983 spin_lock_irq(q
->queue_lock
);
985 blk_queue_congestion_threshold(q
);
986 on_thresh
= queue_congestion_on_threshold(q
);
987 off_thresh
= queue_congestion_off_threshold(q
);
989 blk_queue_for_each_rl(rl
, q
) {
990 if (rl
->count
[BLK_RW_SYNC
] >= on_thresh
)
991 blk_set_congested(rl
, BLK_RW_SYNC
);
992 else if (rl
->count
[BLK_RW_SYNC
] < off_thresh
)
993 blk_clear_congested(rl
, BLK_RW_SYNC
);
995 if (rl
->count
[BLK_RW_ASYNC
] >= on_thresh
)
996 blk_set_congested(rl
, BLK_RW_ASYNC
);
997 else if (rl
->count
[BLK_RW_ASYNC
] < off_thresh
)
998 blk_clear_congested(rl
, BLK_RW_ASYNC
);
1000 if (rl
->count
[BLK_RW_SYNC
] >= q
->nr_requests
) {
1001 blk_set_rl_full(rl
, BLK_RW_SYNC
);
1003 blk_clear_rl_full(rl
, BLK_RW_SYNC
);
1004 wake_up(&rl
->wait
[BLK_RW_SYNC
]);
1007 if (rl
->count
[BLK_RW_ASYNC
] >= q
->nr_requests
) {
1008 blk_set_rl_full(rl
, BLK_RW_ASYNC
);
1010 blk_clear_rl_full(rl
, BLK_RW_ASYNC
);
1011 wake_up(&rl
->wait
[BLK_RW_ASYNC
]);
1015 spin_unlock_irq(q
->queue_lock
);
1020 * Determine if elevator data should be initialized when allocating the
1021 * request associated with @bio.
1023 static bool blk_rq_should_init_elevator(struct bio
*bio
)
1029 * Flush requests do not use the elevator so skip initialization.
1030 * This allows a request to share the flush and elevator data.
1032 if (bio
->bi_rw
& (REQ_PREFLUSH
| REQ_FUA
))
1039 * rq_ioc - determine io_context for request allocation
1040 * @bio: request being allocated is for this bio (can be %NULL)
1042 * Determine io_context to use for request allocation for @bio. May return
1043 * %NULL if %current->io_context doesn't exist.
1045 static struct io_context
*rq_ioc(struct bio
*bio
)
1047 #ifdef CONFIG_BLK_CGROUP
1048 if (bio
&& bio
->bi_ioc
)
1051 return current
->io_context
;
1055 * __get_request - get a free request
1056 * @rl: request list to allocate from
1057 * @op: REQ_OP_READ/REQ_OP_WRITE
1058 * @op_flags: rq_flag_bits
1059 * @bio: bio to allocate request for (can be %NULL)
1060 * @gfp_mask: allocation mask
1062 * Get a free request from @q. This function may fail under memory
1063 * pressure or if @q is dead.
1065 * Must be called with @q->queue_lock held and,
1066 * Returns ERR_PTR on failure, with @q->queue_lock held.
1067 * Returns request pointer on success, with @q->queue_lock *not held*.
1069 static struct request
*__get_request(struct request_list
*rl
, int op
,
1070 int op_flags
, struct bio
*bio
,
1073 struct request_queue
*q
= rl
->q
;
1075 struct elevator_type
*et
= q
->elevator
->type
;
1076 struct io_context
*ioc
= rq_ioc(bio
);
1077 struct io_cq
*icq
= NULL
;
1078 const bool is_sync
= rw_is_sync(op
, op_flags
) != 0;
1081 if (unlikely(blk_queue_dying(q
)))
1082 return ERR_PTR(-ENODEV
);
1084 may_queue
= elv_may_queue(q
, op
, op_flags
);
1085 if (may_queue
== ELV_MQUEUE_NO
)
1088 if (rl
->count
[is_sync
]+1 >= queue_congestion_on_threshold(q
)) {
1089 if (rl
->count
[is_sync
]+1 >= q
->nr_requests
) {
1091 * The queue will fill after this allocation, so set
1092 * it as full, and mark this process as "batching".
1093 * This process will be allowed to complete a batch of
1094 * requests, others will be blocked.
1096 if (!blk_rl_full(rl
, is_sync
)) {
1097 ioc_set_batching(q
, ioc
);
1098 blk_set_rl_full(rl
, is_sync
);
1100 if (may_queue
!= ELV_MQUEUE_MUST
1101 && !ioc_batching(q
, ioc
)) {
1103 * The queue is full and the allocating
1104 * process is not a "batcher", and not
1105 * exempted by the IO scheduler
1107 return ERR_PTR(-ENOMEM
);
1111 blk_set_congested(rl
, is_sync
);
1115 * Only allow batching queuers to allocate up to 50% over the defined
1116 * limit of requests, otherwise we could have thousands of requests
1117 * allocated with any setting of ->nr_requests
1119 if (rl
->count
[is_sync
] >= (3 * q
->nr_requests
/ 2))
1120 return ERR_PTR(-ENOMEM
);
1122 q
->nr_rqs
[is_sync
]++;
1123 rl
->count
[is_sync
]++;
1124 rl
->starved
[is_sync
] = 0;
1127 * Decide whether the new request will be managed by elevator. If
1128 * so, mark @op_flags and increment elvpriv. Non-zero elvpriv will
1129 * prevent the current elevator from being destroyed until the new
1130 * request is freed. This guarantees icq's won't be destroyed and
1131 * makes creating new ones safe.
1133 * Also, lookup icq while holding queue_lock. If it doesn't exist,
1134 * it will be created after releasing queue_lock.
1136 if (blk_rq_should_init_elevator(bio
) && !blk_queue_bypass(q
)) {
1137 op_flags
|= REQ_ELVPRIV
;
1138 q
->nr_rqs_elvpriv
++;
1139 if (et
->icq_cache
&& ioc
)
1140 icq
= ioc_lookup_icq(ioc
, q
);
1143 if (blk_queue_io_stat(q
))
1144 op_flags
|= REQ_IO_STAT
;
1145 spin_unlock_irq(q
->queue_lock
);
1147 /* allocate and init request */
1148 rq
= mempool_alloc(rl
->rq_pool
, gfp_mask
);
1153 blk_rq_set_rl(rq
, rl
);
1154 req_set_op_attrs(rq
, op
, op_flags
| REQ_ALLOCED
);
1157 if (op_flags
& REQ_ELVPRIV
) {
1158 if (unlikely(et
->icq_cache
&& !icq
)) {
1160 icq
= ioc_create_icq(ioc
, q
, gfp_mask
);
1166 if (unlikely(elv_set_request(q
, rq
, bio
, gfp_mask
)))
1169 /* @rq->elv.icq holds io_context until @rq is freed */
1171 get_io_context(icq
->ioc
);
1175 * ioc may be NULL here, and ioc_batching will be false. That's
1176 * OK, if the queue is under the request limit then requests need
1177 * not count toward the nr_batch_requests limit. There will always
1178 * be some limit enforced by BLK_BATCH_TIME.
1180 if (ioc_batching(q
, ioc
))
1181 ioc
->nr_batch_requests
--;
1183 trace_block_getrq(q
, bio
, op
);
1188 * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed
1189 * and may fail indefinitely under memory pressure and thus
1190 * shouldn't stall IO. Treat this request as !elvpriv. This will
1191 * disturb iosched and blkcg but weird is bettern than dead.
1193 printk_ratelimited(KERN_WARNING
"%s: dev %s: request aux data allocation failed, iosched may be disturbed\n",
1194 __func__
, dev_name(q
->backing_dev_info
.dev
));
1196 rq
->cmd_flags
&= ~REQ_ELVPRIV
;
1199 spin_lock_irq(q
->queue_lock
);
1200 q
->nr_rqs_elvpriv
--;
1201 spin_unlock_irq(q
->queue_lock
);
1206 * Allocation failed presumably due to memory. Undo anything we
1207 * might have messed up.
1209 * Allocating task should really be put onto the front of the wait
1210 * queue, but this is pretty rare.
1212 spin_lock_irq(q
->queue_lock
);
1213 freed_request(rl
, op
, op_flags
);
1216 * in the very unlikely event that allocation failed and no
1217 * requests for this direction was pending, mark us starved so that
1218 * freeing of a request in the other direction will notice
1219 * us. another possible fix would be to split the rq mempool into
1223 if (unlikely(rl
->count
[is_sync
] == 0))
1224 rl
->starved
[is_sync
] = 1;
1225 return ERR_PTR(-ENOMEM
);
1229 * get_request - get a free request
1230 * @q: request_queue to allocate request from
1231 * @op: REQ_OP_READ/REQ_OP_WRITE
1232 * @op_flags: rq_flag_bits
1233 * @bio: bio to allocate request for (can be %NULL)
1234 * @gfp_mask: allocation mask
1236 * Get a free request from @q. If %__GFP_DIRECT_RECLAIM is set in @gfp_mask,
1237 * this function keeps retrying under memory pressure and fails iff @q is dead.
1239 * Must be called with @q->queue_lock held and,
1240 * Returns ERR_PTR on failure, with @q->queue_lock held.
1241 * Returns request pointer on success, with @q->queue_lock *not held*.
1243 static struct request
*get_request(struct request_queue
*q
, int op
,
1244 int op_flags
, struct bio
*bio
,
1247 const bool is_sync
= rw_is_sync(op
, op_flags
) != 0;
1249 struct request_list
*rl
;
1252 rl
= blk_get_rl(q
, bio
); /* transferred to @rq on success */
1254 rq
= __get_request(rl
, op
, op_flags
, bio
, gfp_mask
);
1258 if (!gfpflags_allow_blocking(gfp_mask
) || unlikely(blk_queue_dying(q
))) {
1263 /* wait on @rl and retry */
1264 prepare_to_wait_exclusive(&rl
->wait
[is_sync
], &wait
,
1265 TASK_UNINTERRUPTIBLE
);
1267 trace_block_sleeprq(q
, bio
, op
);
1269 spin_unlock_irq(q
->queue_lock
);
1273 * After sleeping, we become a "batching" process and will be able
1274 * to allocate at least one request, and up to a big batch of them
1275 * for a small period time. See ioc_batching, ioc_set_batching
1277 ioc_set_batching(q
, current
->io_context
);
1279 spin_lock_irq(q
->queue_lock
);
1280 finish_wait(&rl
->wait
[is_sync
], &wait
);
1285 static struct request
*blk_old_get_request(struct request_queue
*q
, int rw
,
1290 BUG_ON(rw
!= READ
&& rw
!= WRITE
);
1292 /* create ioc upfront */
1293 create_io_context(gfp_mask
, q
->node
);
1295 spin_lock_irq(q
->queue_lock
);
1296 rq
= get_request(q
, rw
, 0, NULL
, gfp_mask
);
1298 spin_unlock_irq(q
->queue_lock
);
1299 /* q->queue_lock is unlocked at this point */
1304 struct request
*blk_get_request(struct request_queue
*q
, int rw
, gfp_t gfp_mask
)
1307 return blk_mq_alloc_request(q
, rw
,
1308 (gfp_mask
& __GFP_DIRECT_RECLAIM
) ?
1309 0 : BLK_MQ_REQ_NOWAIT
);
1311 return blk_old_get_request(q
, rw
, gfp_mask
);
1313 EXPORT_SYMBOL(blk_get_request
);
1316 * blk_make_request - given a bio, allocate a corresponding struct request.
1317 * @q: target request queue
1318 * @bio: The bio describing the memory mappings that will be submitted for IO.
1319 * It may be a chained-bio properly constructed by block/bio layer.
1320 * @gfp_mask: gfp flags to be used for memory allocation
1322 * blk_make_request is the parallel of generic_make_request for BLOCK_PC
1323 * type commands. Where the struct request needs to be farther initialized by
1324 * the caller. It is passed a &struct bio, which describes the memory info of
1327 * The caller of blk_make_request must make sure that bi_io_vec
1328 * are set to describe the memory buffers. That bio_data_dir() will return
1329 * the needed direction of the request. (And all bio's in the passed bio-chain
1330 * are properly set accordingly)
1332 * If called under none-sleepable conditions, mapped bio buffers must not
1333 * need bouncing, by calling the appropriate masked or flagged allocator,
1334 * suitable for the target device. Otherwise the call to blk_queue_bounce will
1337 * WARNING: When allocating/cloning a bio-chain, careful consideration should be
1338 * given to how you allocate bios. In particular, you cannot use
1339 * __GFP_DIRECT_RECLAIM for anything but the first bio in the chain. Otherwise
1340 * you risk waiting for IO completion of a bio that hasn't been submitted yet,
1341 * thus resulting in a deadlock. Alternatively bios should be allocated using
1342 * bio_kmalloc() instead of bio_alloc(), as that avoids the mempool deadlock.
1343 * If possible a big IO should be split into smaller parts when allocation
1344 * fails. Partial allocation should not be an error, or you risk a live-lock.
1346 struct request
*blk_make_request(struct request_queue
*q
, struct bio
*bio
,
1349 struct request
*rq
= blk_get_request(q
, bio_data_dir(bio
), gfp_mask
);
1354 blk_rq_set_block_pc(rq
);
1357 struct bio
*bounce_bio
= bio
;
1360 blk_queue_bounce(q
, &bounce_bio
);
1361 ret
= blk_rq_append_bio(q
, rq
, bounce_bio
);
1362 if (unlikely(ret
)) {
1363 blk_put_request(rq
);
1364 return ERR_PTR(ret
);
1370 EXPORT_SYMBOL(blk_make_request
);
1373 * blk_rq_set_block_pc - initialize a request to type BLOCK_PC
1374 * @rq: request to be initialized
1377 void blk_rq_set_block_pc(struct request
*rq
)
1379 rq
->cmd_type
= REQ_TYPE_BLOCK_PC
;
1381 rq
->__sector
= (sector_t
) -1;
1382 rq
->bio
= rq
->biotail
= NULL
;
1383 memset(rq
->__cmd
, 0, sizeof(rq
->__cmd
));
1385 EXPORT_SYMBOL(blk_rq_set_block_pc
);
1388 * blk_requeue_request - put a request back on queue
1389 * @q: request queue where request should be inserted
1390 * @rq: request to be inserted
1393 * Drivers often keep queueing requests until the hardware cannot accept
1394 * more, when that condition happens we need to put the request back
1395 * on the queue. Must be called with queue lock held.
1397 void blk_requeue_request(struct request_queue
*q
, struct request
*rq
)
1399 blk_delete_timer(rq
);
1400 blk_clear_rq_complete(rq
);
1401 trace_block_rq_requeue(q
, rq
);
1403 if (rq
->cmd_flags
& REQ_QUEUED
)
1404 blk_queue_end_tag(q
, rq
);
1406 BUG_ON(blk_queued_rq(rq
));
1408 elv_requeue_request(q
, rq
);
1410 EXPORT_SYMBOL(blk_requeue_request
);
1412 static void add_acct_request(struct request_queue
*q
, struct request
*rq
,
1415 blk_account_io_start(rq
, true);
1416 __elv_add_request(q
, rq
, where
);
1419 static void part_round_stats_single(int cpu
, struct hd_struct
*part
,
1424 if (now
== part
->stamp
)
1427 inflight
= part_in_flight(part
);
1429 __part_stat_add(cpu
, part
, time_in_queue
,
1430 inflight
* (now
- part
->stamp
));
1431 __part_stat_add(cpu
, part
, io_ticks
, (now
- part
->stamp
));
1437 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1438 * @cpu: cpu number for stats access
1439 * @part: target partition
1441 * The average IO queue length and utilisation statistics are maintained
1442 * by observing the current state of the queue length and the amount of
1443 * time it has been in this state for.
1445 * Normally, that accounting is done on IO completion, but that can result
1446 * in more than a second's worth of IO being accounted for within any one
1447 * second, leading to >100% utilisation. To deal with that, we call this
1448 * function to do a round-off before returning the results when reading
1449 * /proc/diskstats. This accounts immediately for all queue usage up to
1450 * the current jiffies and restarts the counters again.
1452 void part_round_stats(int cpu
, struct hd_struct
*part
)
1454 unsigned long now
= jiffies
;
1457 part_round_stats_single(cpu
, &part_to_disk(part
)->part0
, now
);
1458 part_round_stats_single(cpu
, part
, now
);
1460 EXPORT_SYMBOL_GPL(part_round_stats
);
1463 static void blk_pm_put_request(struct request
*rq
)
1465 if (rq
->q
->dev
&& !(rq
->cmd_flags
& REQ_PM
) && !--rq
->q
->nr_pending
)
1466 pm_runtime_mark_last_busy(rq
->q
->dev
);
1469 static inline void blk_pm_put_request(struct request
*rq
) {}
1473 * queue lock must be held
1475 void __blk_put_request(struct request_queue
*q
, struct request
*req
)
1481 blk_mq_free_request(req
);
1485 blk_pm_put_request(req
);
1487 elv_completed_request(q
, req
);
1489 /* this is a bio leak */
1490 WARN_ON(req
->bio
!= NULL
);
1493 * Request may not have originated from ll_rw_blk. if not,
1494 * it didn't come out of our reserved rq pools
1496 if (req
->cmd_flags
& REQ_ALLOCED
) {
1497 unsigned int flags
= req
->cmd_flags
;
1498 int op
= req_op(req
);
1499 struct request_list
*rl
= blk_rq_rl(req
);
1501 BUG_ON(!list_empty(&req
->queuelist
));
1502 BUG_ON(ELV_ON_HASH(req
));
1504 blk_free_request(rl
, req
);
1505 freed_request(rl
, op
, flags
);
1509 EXPORT_SYMBOL_GPL(__blk_put_request
);
1511 void blk_put_request(struct request
*req
)
1513 struct request_queue
*q
= req
->q
;
1516 blk_mq_free_request(req
);
1518 unsigned long flags
;
1520 spin_lock_irqsave(q
->queue_lock
, flags
);
1521 __blk_put_request(q
, req
);
1522 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1525 EXPORT_SYMBOL(blk_put_request
);
1528 * blk_add_request_payload - add a payload to a request
1529 * @rq: request to update
1530 * @page: page backing the payload
1531 * @offset: offset in page
1532 * @len: length of the payload.
1534 * This allows to later add a payload to an already submitted request by
1535 * a block driver. The driver needs to take care of freeing the payload
1538 * Note that this is a quite horrible hack and nothing but handling of
1539 * discard requests should ever use it.
1541 void blk_add_request_payload(struct request
*rq
, struct page
*page
,
1542 int offset
, unsigned int len
)
1544 struct bio
*bio
= rq
->bio
;
1546 bio
->bi_io_vec
->bv_page
= page
;
1547 bio
->bi_io_vec
->bv_offset
= offset
;
1548 bio
->bi_io_vec
->bv_len
= len
;
1550 bio
->bi_iter
.bi_size
= len
;
1552 bio
->bi_phys_segments
= 1;
1554 rq
->__data_len
= rq
->resid_len
= len
;
1555 rq
->nr_phys_segments
= 1;
1557 EXPORT_SYMBOL_GPL(blk_add_request_payload
);
1559 bool bio_attempt_back_merge(struct request_queue
*q
, struct request
*req
,
1562 const int ff
= bio
->bi_rw
& REQ_FAILFAST_MASK
;
1564 if (!ll_back_merge_fn(q
, req
, bio
))
1567 trace_block_bio_backmerge(q
, req
, bio
);
1569 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
1570 blk_rq_set_mixed_merge(req
);
1572 req
->biotail
->bi_next
= bio
;
1574 req
->__data_len
+= bio
->bi_iter
.bi_size
;
1575 req
->ioprio
= ioprio_best(req
->ioprio
, bio_prio(bio
));
1577 blk_account_io_start(req
, false);
1581 bool bio_attempt_front_merge(struct request_queue
*q
, struct request
*req
,
1584 const int ff
= bio
->bi_rw
& REQ_FAILFAST_MASK
;
1586 if (!ll_front_merge_fn(q
, req
, bio
))
1589 trace_block_bio_frontmerge(q
, req
, bio
);
1591 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
1592 blk_rq_set_mixed_merge(req
);
1594 bio
->bi_next
= req
->bio
;
1597 req
->__sector
= bio
->bi_iter
.bi_sector
;
1598 req
->__data_len
+= bio
->bi_iter
.bi_size
;
1599 req
->ioprio
= ioprio_best(req
->ioprio
, bio_prio(bio
));
1601 blk_account_io_start(req
, false);
1606 * blk_attempt_plug_merge - try to merge with %current's plugged list
1607 * @q: request_queue new bio is being queued at
1608 * @bio: new bio being queued
1609 * @request_count: out parameter for number of traversed plugged requests
1610 * @same_queue_rq: pointer to &struct request that gets filled in when
1611 * another request associated with @q is found on the plug list
1612 * (optional, may be %NULL)
1614 * Determine whether @bio being queued on @q can be merged with a request
1615 * on %current's plugged list. Returns %true if merge was successful,
1618 * Plugging coalesces IOs from the same issuer for the same purpose without
1619 * going through @q->queue_lock. As such it's more of an issuing mechanism
1620 * than scheduling, and the request, while may have elvpriv data, is not
1621 * added on the elevator at this point. In addition, we don't have
1622 * reliable access to the elevator outside queue lock. Only check basic
1623 * merging parameters without querying the elevator.
1625 * Caller must ensure !blk_queue_nomerges(q) beforehand.
1627 bool blk_attempt_plug_merge(struct request_queue
*q
, struct bio
*bio
,
1628 unsigned int *request_count
,
1629 struct request
**same_queue_rq
)
1631 struct blk_plug
*plug
;
1634 struct list_head
*plug_list
;
1636 plug
= current
->plug
;
1642 plug_list
= &plug
->mq_list
;
1644 plug_list
= &plug
->list
;
1646 list_for_each_entry_reverse(rq
, plug_list
, queuelist
) {
1652 * Only blk-mq multiple hardware queues case checks the
1653 * rq in the same queue, there should be only one such
1657 *same_queue_rq
= rq
;
1660 if (rq
->q
!= q
|| !blk_rq_merge_ok(rq
, bio
))
1663 el_ret
= blk_try_merge(rq
, bio
);
1664 if (el_ret
== ELEVATOR_BACK_MERGE
) {
1665 ret
= bio_attempt_back_merge(q
, rq
, bio
);
1668 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
1669 ret
= bio_attempt_front_merge(q
, rq
, bio
);
1678 unsigned int blk_plug_queued_count(struct request_queue
*q
)
1680 struct blk_plug
*plug
;
1682 struct list_head
*plug_list
;
1683 unsigned int ret
= 0;
1685 plug
= current
->plug
;
1690 plug_list
= &plug
->mq_list
;
1692 plug_list
= &plug
->list
;
1694 list_for_each_entry(rq
, plug_list
, queuelist
) {
1702 void init_request_from_bio(struct request
*req
, struct bio
*bio
)
1704 req
->cmd_type
= REQ_TYPE_FS
;
1706 req
->cmd_flags
|= bio
->bi_rw
& REQ_COMMON_MASK
;
1707 if (bio
->bi_rw
& REQ_RAHEAD
)
1708 req
->cmd_flags
|= REQ_FAILFAST_MASK
;
1711 req
->__sector
= bio
->bi_iter
.bi_sector
;
1712 req
->ioprio
= bio_prio(bio
);
1713 blk_rq_bio_prep(req
->q
, req
, bio
);
1716 static blk_qc_t
blk_queue_bio(struct request_queue
*q
, struct bio
*bio
)
1718 const bool sync
= !!(bio
->bi_rw
& REQ_SYNC
);
1719 struct blk_plug
*plug
;
1720 int el_ret
, rw_flags
= 0, where
= ELEVATOR_INSERT_SORT
;
1721 struct request
*req
;
1722 unsigned int request_count
= 0;
1725 * low level driver can indicate that it wants pages above a
1726 * certain limit bounced to low memory (ie for highmem, or even
1727 * ISA dma in theory)
1729 blk_queue_bounce(q
, &bio
);
1731 blk_queue_split(q
, &bio
, q
->bio_split
);
1733 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1734 bio
->bi_error
= -EIO
;
1736 return BLK_QC_T_NONE
;
1739 if (bio
->bi_rw
& (REQ_PREFLUSH
| REQ_FUA
)) {
1740 spin_lock_irq(q
->queue_lock
);
1741 where
= ELEVATOR_INSERT_FLUSH
;
1746 * Check if we can merge with the plugged list before grabbing
1749 if (!blk_queue_nomerges(q
)) {
1750 if (blk_attempt_plug_merge(q
, bio
, &request_count
, NULL
))
1751 return BLK_QC_T_NONE
;
1753 request_count
= blk_plug_queued_count(q
);
1755 spin_lock_irq(q
->queue_lock
);
1757 el_ret
= elv_merge(q
, &req
, bio
);
1758 if (el_ret
== ELEVATOR_BACK_MERGE
) {
1759 if (bio_attempt_back_merge(q
, req
, bio
)) {
1760 elv_bio_merged(q
, req
, bio
);
1761 if (!attempt_back_merge(q
, req
))
1762 elv_merged_request(q
, req
, el_ret
);
1765 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
1766 if (bio_attempt_front_merge(q
, req
, bio
)) {
1767 elv_bio_merged(q
, req
, bio
);
1768 if (!attempt_front_merge(q
, req
))
1769 elv_merged_request(q
, req
, el_ret
);
1776 * This sync check and mask will be re-done in init_request_from_bio(),
1777 * but we need to set it earlier to expose the sync flag to the
1778 * rq allocator and io schedulers.
1781 rw_flags
|= REQ_SYNC
;
1784 * Grab a free request. This is might sleep but can not fail.
1785 * Returns with the queue unlocked.
1787 req
= get_request(q
, bio_data_dir(bio
), rw_flags
, bio
, GFP_NOIO
);
1789 bio
->bi_error
= PTR_ERR(req
);
1795 * After dropping the lock and possibly sleeping here, our request
1796 * may now be mergeable after it had proven unmergeable (above).
1797 * We don't worry about that case for efficiency. It won't happen
1798 * often, and the elevators are able to handle it.
1800 init_request_from_bio(req
, bio
);
1802 if (test_bit(QUEUE_FLAG_SAME_COMP
, &q
->queue_flags
))
1803 req
->cpu
= raw_smp_processor_id();
1805 plug
= current
->plug
;
1808 * If this is the first request added after a plug, fire
1812 trace_block_plug(q
);
1814 if (request_count
>= BLK_MAX_REQUEST_COUNT
) {
1815 blk_flush_plug_list(plug
, false);
1816 trace_block_plug(q
);
1819 list_add_tail(&req
->queuelist
, &plug
->list
);
1820 blk_account_io_start(req
, true);
1822 spin_lock_irq(q
->queue_lock
);
1823 add_acct_request(q
, req
, where
);
1826 spin_unlock_irq(q
->queue_lock
);
1829 return BLK_QC_T_NONE
;
1833 * If bio->bi_dev is a partition, remap the location
1835 static inline void blk_partition_remap(struct bio
*bio
)
1837 struct block_device
*bdev
= bio
->bi_bdev
;
1839 if (bio_sectors(bio
) && bdev
!= bdev
->bd_contains
) {
1840 struct hd_struct
*p
= bdev
->bd_part
;
1842 bio
->bi_iter
.bi_sector
+= p
->start_sect
;
1843 bio
->bi_bdev
= bdev
->bd_contains
;
1845 trace_block_bio_remap(bdev_get_queue(bio
->bi_bdev
), bio
,
1847 bio
->bi_iter
.bi_sector
- p
->start_sect
);
1851 static void handle_bad_sector(struct bio
*bio
)
1853 char b
[BDEVNAME_SIZE
];
1855 printk(KERN_INFO
"attempt to access beyond end of device\n");
1856 printk(KERN_INFO
"%s: rw=%d, want=%Lu, limit=%Lu\n",
1857 bdevname(bio
->bi_bdev
, b
),
1859 (unsigned long long)bio_end_sector(bio
),
1860 (long long)(i_size_read(bio
->bi_bdev
->bd_inode
) >> 9));
1863 #ifdef CONFIG_FAIL_MAKE_REQUEST
1865 static DECLARE_FAULT_ATTR(fail_make_request
);
1867 static int __init
setup_fail_make_request(char *str
)
1869 return setup_fault_attr(&fail_make_request
, str
);
1871 __setup("fail_make_request=", setup_fail_make_request
);
1873 static bool should_fail_request(struct hd_struct
*part
, unsigned int bytes
)
1875 return part
->make_it_fail
&& should_fail(&fail_make_request
, bytes
);
1878 static int __init
fail_make_request_debugfs(void)
1880 struct dentry
*dir
= fault_create_debugfs_attr("fail_make_request",
1881 NULL
, &fail_make_request
);
1883 return PTR_ERR_OR_ZERO(dir
);
1886 late_initcall(fail_make_request_debugfs
);
1888 #else /* CONFIG_FAIL_MAKE_REQUEST */
1890 static inline bool should_fail_request(struct hd_struct
*part
,
1896 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1899 * Check whether this bio extends beyond the end of the device.
1901 static inline int bio_check_eod(struct bio
*bio
, unsigned int nr_sectors
)
1908 /* Test device or partition size, when known. */
1909 maxsector
= i_size_read(bio
->bi_bdev
->bd_inode
) >> 9;
1911 sector_t sector
= bio
->bi_iter
.bi_sector
;
1913 if (maxsector
< nr_sectors
|| maxsector
- nr_sectors
< sector
) {
1915 * This may well happen - the kernel calls bread()
1916 * without checking the size of the device, e.g., when
1917 * mounting a device.
1919 handle_bad_sector(bio
);
1927 static noinline_for_stack
bool
1928 generic_make_request_checks(struct bio
*bio
)
1930 struct request_queue
*q
;
1931 int nr_sectors
= bio_sectors(bio
);
1933 char b
[BDEVNAME_SIZE
];
1934 struct hd_struct
*part
;
1938 if (bio_check_eod(bio
, nr_sectors
))
1941 q
= bdev_get_queue(bio
->bi_bdev
);
1944 "generic_make_request: Trying to access "
1945 "nonexistent block-device %s (%Lu)\n",
1946 bdevname(bio
->bi_bdev
, b
),
1947 (long long) bio
->bi_iter
.bi_sector
);
1951 part
= bio
->bi_bdev
->bd_part
;
1952 if (should_fail_request(part
, bio
->bi_iter
.bi_size
) ||
1953 should_fail_request(&part_to_disk(part
)->part0
,
1954 bio
->bi_iter
.bi_size
))
1958 * If this device has partitions, remap block n
1959 * of partition p to block n+start(p) of the disk.
1961 blk_partition_remap(bio
);
1963 if (bio_check_eod(bio
, nr_sectors
))
1967 * Filter flush bio's early so that make_request based
1968 * drivers without flush support don't have to worry
1971 if ((bio
->bi_rw
& (REQ_PREFLUSH
| REQ_FUA
)) &&
1972 !test_bit(QUEUE_FLAG_WC
, &q
->queue_flags
)) {
1973 bio
->bi_rw
&= ~(REQ_PREFLUSH
| REQ_FUA
);
1980 switch (bio_op(bio
)) {
1981 case REQ_OP_DISCARD
:
1982 if (!blk_queue_discard(q
))
1985 case REQ_OP_SECURE_ERASE
:
1986 if (!blk_queue_secure_erase(q
))
1989 case REQ_OP_WRITE_SAME
:
1990 if (!bdev_write_same(bio
->bi_bdev
))
1998 * Various block parts want %current->io_context and lazy ioc
1999 * allocation ends up trading a lot of pain for a small amount of
2000 * memory. Just allocate it upfront. This may fail and block
2001 * layer knows how to live with it.
2003 create_io_context(GFP_ATOMIC
, q
->node
);
2005 if (!blkcg_bio_issue_check(q
, bio
))
2008 trace_block_bio_queue(q
, bio
);
2014 bio
->bi_error
= err
;
2020 * generic_make_request - hand a buffer to its device driver for I/O
2021 * @bio: The bio describing the location in memory and on the device.
2023 * generic_make_request() is used to make I/O requests of block
2024 * devices. It is passed a &struct bio, which describes the I/O that needs
2027 * generic_make_request() does not return any status. The
2028 * success/failure status of the request, along with notification of
2029 * completion, is delivered asynchronously through the bio->bi_end_io
2030 * function described (one day) else where.
2032 * The caller of generic_make_request must make sure that bi_io_vec
2033 * are set to describe the memory buffer, and that bi_dev and bi_sector are
2034 * set to describe the device address, and the
2035 * bi_end_io and optionally bi_private are set to describe how
2036 * completion notification should be signaled.
2038 * generic_make_request and the drivers it calls may use bi_next if this
2039 * bio happens to be merged with someone else, and may resubmit the bio to
2040 * a lower device by calling into generic_make_request recursively, which
2041 * means the bio should NOT be touched after the call to ->make_request_fn.
2043 blk_qc_t
generic_make_request(struct bio
*bio
)
2045 struct bio_list bio_list_on_stack
;
2046 blk_qc_t ret
= BLK_QC_T_NONE
;
2048 if (!generic_make_request_checks(bio
))
2052 * We only want one ->make_request_fn to be active at a time, else
2053 * stack usage with stacked devices could be a problem. So use
2054 * current->bio_list to keep a list of requests submited by a
2055 * make_request_fn function. current->bio_list is also used as a
2056 * flag to say if generic_make_request is currently active in this
2057 * task or not. If it is NULL, then no make_request is active. If
2058 * it is non-NULL, then a make_request is active, and new requests
2059 * should be added at the tail
2061 if (current
->bio_list
) {
2062 bio_list_add(current
->bio_list
, bio
);
2066 /* following loop may be a bit non-obvious, and so deserves some
2068 * Before entering the loop, bio->bi_next is NULL (as all callers
2069 * ensure that) so we have a list with a single bio.
2070 * We pretend that we have just taken it off a longer list, so
2071 * we assign bio_list to a pointer to the bio_list_on_stack,
2072 * thus initialising the bio_list of new bios to be
2073 * added. ->make_request() may indeed add some more bios
2074 * through a recursive call to generic_make_request. If it
2075 * did, we find a non-NULL value in bio_list and re-enter the loop
2076 * from the top. In this case we really did just take the bio
2077 * of the top of the list (no pretending) and so remove it from
2078 * bio_list, and call into ->make_request() again.
2080 BUG_ON(bio
->bi_next
);
2081 bio_list_init(&bio_list_on_stack
);
2082 current
->bio_list
= &bio_list_on_stack
;
2084 struct request_queue
*q
= bdev_get_queue(bio
->bi_bdev
);
2086 if (likely(blk_queue_enter(q
, false) == 0)) {
2087 ret
= q
->make_request_fn(q
, bio
);
2091 bio
= bio_list_pop(current
->bio_list
);
2093 struct bio
*bio_next
= bio_list_pop(current
->bio_list
);
2099 current
->bio_list
= NULL
; /* deactivate */
2104 EXPORT_SYMBOL(generic_make_request
);
2107 * submit_bio - submit a bio to the block device layer for I/O
2108 * @bio: The &struct bio which describes the I/O
2110 * submit_bio() is very similar in purpose to generic_make_request(), and
2111 * uses that function to do most of the work. Both are fairly rough
2112 * interfaces; @bio must be presetup and ready for I/O.
2115 blk_qc_t
submit_bio(struct bio
*bio
)
2118 * If it's a regular read/write or a barrier with data attached,
2119 * go through the normal accounting stuff before submission.
2121 if (bio_has_data(bio
)) {
2124 if (unlikely(bio_op(bio
) == REQ_OP_WRITE_SAME
))
2125 count
= bdev_logical_block_size(bio
->bi_bdev
) >> 9;
2127 count
= bio_sectors(bio
);
2129 if (op_is_write(bio_op(bio
))) {
2130 count_vm_events(PGPGOUT
, count
);
2132 task_io_account_read(bio
->bi_iter
.bi_size
);
2133 count_vm_events(PGPGIN
, count
);
2136 if (unlikely(block_dump
)) {
2137 char b
[BDEVNAME_SIZE
];
2138 printk(KERN_DEBUG
"%s(%d): %s block %Lu on %s (%u sectors)\n",
2139 current
->comm
, task_pid_nr(current
),
2140 op_is_write(bio_op(bio
)) ? "WRITE" : "READ",
2141 (unsigned long long)bio
->bi_iter
.bi_sector
,
2142 bdevname(bio
->bi_bdev
, b
),
2147 return generic_make_request(bio
);
2149 EXPORT_SYMBOL(submit_bio
);
2152 * blk_cloned_rq_check_limits - Helper function to check a cloned request
2153 * for new the queue limits
2155 * @rq: the request being checked
2158 * @rq may have been made based on weaker limitations of upper-level queues
2159 * in request stacking drivers, and it may violate the limitation of @q.
2160 * Since the block layer and the underlying device driver trust @rq
2161 * after it is inserted to @q, it should be checked against @q before
2162 * the insertion using this generic function.
2164 * Request stacking drivers like request-based dm may change the queue
2165 * limits when retrying requests on other queues. Those requests need
2166 * to be checked against the new queue limits again during dispatch.
2168 static int blk_cloned_rq_check_limits(struct request_queue
*q
,
2171 if (blk_rq_sectors(rq
) > blk_queue_get_max_sectors(q
, req_op(rq
))) {
2172 printk(KERN_ERR
"%s: over max size limit.\n", __func__
);
2177 * queue's settings related to segment counting like q->bounce_pfn
2178 * may differ from that of other stacking queues.
2179 * Recalculate it to check the request correctly on this queue's
2182 blk_recalc_rq_segments(rq
);
2183 if (rq
->nr_phys_segments
> queue_max_segments(q
)) {
2184 printk(KERN_ERR
"%s: over max segments limit.\n", __func__
);
2192 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
2193 * @q: the queue to submit the request
2194 * @rq: the request being queued
2196 int blk_insert_cloned_request(struct request_queue
*q
, struct request
*rq
)
2198 unsigned long flags
;
2199 int where
= ELEVATOR_INSERT_BACK
;
2201 if (blk_cloned_rq_check_limits(q
, rq
))
2205 should_fail_request(&rq
->rq_disk
->part0
, blk_rq_bytes(rq
)))
2209 if (blk_queue_io_stat(q
))
2210 blk_account_io_start(rq
, true);
2211 blk_mq_insert_request(rq
, false, true, false);
2215 spin_lock_irqsave(q
->queue_lock
, flags
);
2216 if (unlikely(blk_queue_dying(q
))) {
2217 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2222 * Submitting request must be dequeued before calling this function
2223 * because it will be linked to another request_queue
2225 BUG_ON(blk_queued_rq(rq
));
2227 if (rq
->cmd_flags
& (REQ_PREFLUSH
| REQ_FUA
))
2228 where
= ELEVATOR_INSERT_FLUSH
;
2230 add_acct_request(q
, rq
, where
);
2231 if (where
== ELEVATOR_INSERT_FLUSH
)
2233 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2237 EXPORT_SYMBOL_GPL(blk_insert_cloned_request
);
2240 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
2241 * @rq: request to examine
2244 * A request could be merge of IOs which require different failure
2245 * handling. This function determines the number of bytes which
2246 * can be failed from the beginning of the request without
2247 * crossing into area which need to be retried further.
2250 * The number of bytes to fail.
2253 * queue_lock must be held.
2255 unsigned int blk_rq_err_bytes(const struct request
*rq
)
2257 unsigned int ff
= rq
->cmd_flags
& REQ_FAILFAST_MASK
;
2258 unsigned int bytes
= 0;
2261 if (!(rq
->cmd_flags
& REQ_MIXED_MERGE
))
2262 return blk_rq_bytes(rq
);
2265 * Currently the only 'mixing' which can happen is between
2266 * different fastfail types. We can safely fail portions
2267 * which have all the failfast bits that the first one has -
2268 * the ones which are at least as eager to fail as the first
2271 for (bio
= rq
->bio
; bio
; bio
= bio
->bi_next
) {
2272 if ((bio
->bi_rw
& ff
) != ff
)
2274 bytes
+= bio
->bi_iter
.bi_size
;
2277 /* this could lead to infinite loop */
2278 BUG_ON(blk_rq_bytes(rq
) && !bytes
);
2281 EXPORT_SYMBOL_GPL(blk_rq_err_bytes
);
2283 void blk_account_io_completion(struct request
*req
, unsigned int bytes
)
2285 if (blk_do_io_stat(req
)) {
2286 const int rw
= rq_data_dir(req
);
2287 struct hd_struct
*part
;
2290 cpu
= part_stat_lock();
2292 part_stat_add(cpu
, part
, sectors
[rw
], bytes
>> 9);
2297 void blk_account_io_done(struct request
*req
)
2300 * Account IO completion. flush_rq isn't accounted as a
2301 * normal IO on queueing nor completion. Accounting the
2302 * containing request is enough.
2304 if (blk_do_io_stat(req
) && !(req
->cmd_flags
& REQ_FLUSH_SEQ
)) {
2305 unsigned long duration
= jiffies
- req
->start_time
;
2306 const int rw
= rq_data_dir(req
);
2307 struct hd_struct
*part
;
2310 cpu
= part_stat_lock();
2313 part_stat_inc(cpu
, part
, ios
[rw
]);
2314 part_stat_add(cpu
, part
, ticks
[rw
], duration
);
2315 part_round_stats(cpu
, part
);
2316 part_dec_in_flight(part
, rw
);
2318 hd_struct_put(part
);
2325 * Don't process normal requests when queue is suspended
2326 * or in the process of suspending/resuming
2328 static struct request
*blk_pm_peek_request(struct request_queue
*q
,
2331 if (q
->dev
&& (q
->rpm_status
== RPM_SUSPENDED
||
2332 (q
->rpm_status
!= RPM_ACTIVE
&& !(rq
->cmd_flags
& REQ_PM
))))
2338 static inline struct request
*blk_pm_peek_request(struct request_queue
*q
,
2345 void blk_account_io_start(struct request
*rq
, bool new_io
)
2347 struct hd_struct
*part
;
2348 int rw
= rq_data_dir(rq
);
2351 if (!blk_do_io_stat(rq
))
2354 cpu
= part_stat_lock();
2358 part_stat_inc(cpu
, part
, merges
[rw
]);
2360 part
= disk_map_sector_rcu(rq
->rq_disk
, blk_rq_pos(rq
));
2361 if (!hd_struct_try_get(part
)) {
2363 * The partition is already being removed,
2364 * the request will be accounted on the disk only
2366 * We take a reference on disk->part0 although that
2367 * partition will never be deleted, so we can treat
2368 * it as any other partition.
2370 part
= &rq
->rq_disk
->part0
;
2371 hd_struct_get(part
);
2373 part_round_stats(cpu
, part
);
2374 part_inc_in_flight(part
, rw
);
2382 * blk_peek_request - peek at the top of a request queue
2383 * @q: request queue to peek at
2386 * Return the request at the top of @q. The returned request
2387 * should be started using blk_start_request() before LLD starts
2391 * Pointer to the request at the top of @q if available. Null
2395 * queue_lock must be held.
2397 struct request
*blk_peek_request(struct request_queue
*q
)
2402 while ((rq
= __elv_next_request(q
)) != NULL
) {
2404 rq
= blk_pm_peek_request(q
, rq
);
2408 if (!(rq
->cmd_flags
& REQ_STARTED
)) {
2410 * This is the first time the device driver
2411 * sees this request (possibly after
2412 * requeueing). Notify IO scheduler.
2414 if (rq
->cmd_flags
& REQ_SORTED
)
2415 elv_activate_rq(q
, rq
);
2418 * just mark as started even if we don't start
2419 * it, a request that has been delayed should
2420 * not be passed by new incoming requests
2422 rq
->cmd_flags
|= REQ_STARTED
;
2423 trace_block_rq_issue(q
, rq
);
2426 if (!q
->boundary_rq
|| q
->boundary_rq
== rq
) {
2427 q
->end_sector
= rq_end_sector(rq
);
2428 q
->boundary_rq
= NULL
;
2431 if (rq
->cmd_flags
& REQ_DONTPREP
)
2434 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
2436 * make sure space for the drain appears we
2437 * know we can do this because max_hw_segments
2438 * has been adjusted to be one fewer than the
2441 rq
->nr_phys_segments
++;
2447 ret
= q
->prep_rq_fn(q
, rq
);
2448 if (ret
== BLKPREP_OK
) {
2450 } else if (ret
== BLKPREP_DEFER
) {
2452 * the request may have been (partially) prepped.
2453 * we need to keep this request in the front to
2454 * avoid resource deadlock. REQ_STARTED will
2455 * prevent other fs requests from passing this one.
2457 if (q
->dma_drain_size
&& blk_rq_bytes(rq
) &&
2458 !(rq
->cmd_flags
& REQ_DONTPREP
)) {
2460 * remove the space for the drain we added
2461 * so that we don't add it again
2463 --rq
->nr_phys_segments
;
2468 } else if (ret
== BLKPREP_KILL
|| ret
== BLKPREP_INVALID
) {
2469 int err
= (ret
== BLKPREP_INVALID
) ? -EREMOTEIO
: -EIO
;
2471 rq
->cmd_flags
|= REQ_QUIET
;
2473 * Mark this request as started so we don't trigger
2474 * any debug logic in the end I/O path.
2476 blk_start_request(rq
);
2477 __blk_end_request_all(rq
, err
);
2479 printk(KERN_ERR
"%s: bad return=%d\n", __func__
, ret
);
2486 EXPORT_SYMBOL(blk_peek_request
);
2488 void blk_dequeue_request(struct request
*rq
)
2490 struct request_queue
*q
= rq
->q
;
2492 BUG_ON(list_empty(&rq
->queuelist
));
2493 BUG_ON(ELV_ON_HASH(rq
));
2495 list_del_init(&rq
->queuelist
);
2498 * the time frame between a request being removed from the lists
2499 * and to it is freed is accounted as io that is in progress at
2502 if (blk_account_rq(rq
)) {
2503 q
->in_flight
[rq_is_sync(rq
)]++;
2504 set_io_start_time_ns(rq
);
2509 * blk_start_request - start request processing on the driver
2510 * @req: request to dequeue
2513 * Dequeue @req and start timeout timer on it. This hands off the
2514 * request to the driver.
2516 * Block internal functions which don't want to start timer should
2517 * call blk_dequeue_request().
2520 * queue_lock must be held.
2522 void blk_start_request(struct request
*req
)
2524 blk_dequeue_request(req
);
2527 * We are now handing the request to the hardware, initialize
2528 * resid_len to full count and add the timeout handler.
2530 req
->resid_len
= blk_rq_bytes(req
);
2531 if (unlikely(blk_bidi_rq(req
)))
2532 req
->next_rq
->resid_len
= blk_rq_bytes(req
->next_rq
);
2534 BUG_ON(test_bit(REQ_ATOM_COMPLETE
, &req
->atomic_flags
));
2537 EXPORT_SYMBOL(blk_start_request
);
2540 * blk_fetch_request - fetch a request from a request queue
2541 * @q: request queue to fetch a request from
2544 * Return the request at the top of @q. The request is started on
2545 * return and LLD can start processing it immediately.
2548 * Pointer to the request at the top of @q if available. Null
2552 * queue_lock must be held.
2554 struct request
*blk_fetch_request(struct request_queue
*q
)
2558 rq
= blk_peek_request(q
);
2560 blk_start_request(rq
);
2563 EXPORT_SYMBOL(blk_fetch_request
);
2566 * blk_update_request - Special helper function for request stacking drivers
2567 * @req: the request being processed
2568 * @error: %0 for success, < %0 for error
2569 * @nr_bytes: number of bytes to complete @req
2572 * Ends I/O on a number of bytes attached to @req, but doesn't complete
2573 * the request structure even if @req doesn't have leftover.
2574 * If @req has leftover, sets it up for the next range of segments.
2576 * This special helper function is only for request stacking drivers
2577 * (e.g. request-based dm) so that they can handle partial completion.
2578 * Actual device drivers should use blk_end_request instead.
2580 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
2581 * %false return from this function.
2584 * %false - this request doesn't have any more data
2585 * %true - this request has more data
2587 bool blk_update_request(struct request
*req
, int error
, unsigned int nr_bytes
)
2591 trace_block_rq_complete(req
->q
, req
, nr_bytes
);
2597 * For fs requests, rq is just carrier of independent bio's
2598 * and each partial completion should be handled separately.
2599 * Reset per-request error on each partial completion.
2601 * TODO: tj: This is too subtle. It would be better to let
2602 * low level drivers do what they see fit.
2604 if (req
->cmd_type
== REQ_TYPE_FS
)
2607 if (error
&& req
->cmd_type
== REQ_TYPE_FS
&&
2608 !(req
->cmd_flags
& REQ_QUIET
)) {
2613 error_type
= "recoverable transport";
2616 error_type
= "critical target";
2619 error_type
= "critical nexus";
2622 error_type
= "timeout";
2625 error_type
= "critical space allocation";
2628 error_type
= "critical medium";
2635 printk_ratelimited(KERN_ERR
"%s: %s error, dev %s, sector %llu\n",
2636 __func__
, error_type
, req
->rq_disk
?
2637 req
->rq_disk
->disk_name
: "?",
2638 (unsigned long long)blk_rq_pos(req
));
2642 blk_account_io_completion(req
, nr_bytes
);
2646 struct bio
*bio
= req
->bio
;
2647 unsigned bio_bytes
= min(bio
->bi_iter
.bi_size
, nr_bytes
);
2649 if (bio_bytes
== bio
->bi_iter
.bi_size
)
2650 req
->bio
= bio
->bi_next
;
2652 req_bio_endio(req
, bio
, bio_bytes
, error
);
2654 total_bytes
+= bio_bytes
;
2655 nr_bytes
-= bio_bytes
;
2666 * Reset counters so that the request stacking driver
2667 * can find how many bytes remain in the request
2670 req
->__data_len
= 0;
2674 req
->__data_len
-= total_bytes
;
2676 /* update sector only for requests with clear definition of sector */
2677 if (req
->cmd_type
== REQ_TYPE_FS
)
2678 req
->__sector
+= total_bytes
>> 9;
2680 /* mixed attributes always follow the first bio */
2681 if (req
->cmd_flags
& REQ_MIXED_MERGE
) {
2682 req
->cmd_flags
&= ~REQ_FAILFAST_MASK
;
2683 req
->cmd_flags
|= req
->bio
->bi_rw
& REQ_FAILFAST_MASK
;
2687 * If total number of sectors is less than the first segment
2688 * size, something has gone terribly wrong.
2690 if (blk_rq_bytes(req
) < blk_rq_cur_bytes(req
)) {
2691 blk_dump_rq_flags(req
, "request botched");
2692 req
->__data_len
= blk_rq_cur_bytes(req
);
2695 /* recalculate the number of segments */
2696 blk_recalc_rq_segments(req
);
2700 EXPORT_SYMBOL_GPL(blk_update_request
);
2702 static bool blk_update_bidi_request(struct request
*rq
, int error
,
2703 unsigned int nr_bytes
,
2704 unsigned int bidi_bytes
)
2706 if (blk_update_request(rq
, error
, nr_bytes
))
2709 /* Bidi request must be completed as a whole */
2710 if (unlikely(blk_bidi_rq(rq
)) &&
2711 blk_update_request(rq
->next_rq
, error
, bidi_bytes
))
2714 if (blk_queue_add_random(rq
->q
))
2715 add_disk_randomness(rq
->rq_disk
);
2721 * blk_unprep_request - unprepare a request
2724 * This function makes a request ready for complete resubmission (or
2725 * completion). It happens only after all error handling is complete,
2726 * so represents the appropriate moment to deallocate any resources
2727 * that were allocated to the request in the prep_rq_fn. The queue
2728 * lock is held when calling this.
2730 void blk_unprep_request(struct request
*req
)
2732 struct request_queue
*q
= req
->q
;
2734 req
->cmd_flags
&= ~REQ_DONTPREP
;
2735 if (q
->unprep_rq_fn
)
2736 q
->unprep_rq_fn(q
, req
);
2738 EXPORT_SYMBOL_GPL(blk_unprep_request
);
2741 * queue lock must be held
2743 void blk_finish_request(struct request
*req
, int error
)
2745 if (req
->cmd_flags
& REQ_QUEUED
)
2746 blk_queue_end_tag(req
->q
, req
);
2748 BUG_ON(blk_queued_rq(req
));
2750 if (unlikely(laptop_mode
) && req
->cmd_type
== REQ_TYPE_FS
)
2751 laptop_io_completion(&req
->q
->backing_dev_info
);
2753 blk_delete_timer(req
);
2755 if (req
->cmd_flags
& REQ_DONTPREP
)
2756 blk_unprep_request(req
);
2758 blk_account_io_done(req
);
2761 req
->end_io(req
, error
);
2763 if (blk_bidi_rq(req
))
2764 __blk_put_request(req
->next_rq
->q
, req
->next_rq
);
2766 __blk_put_request(req
->q
, req
);
2769 EXPORT_SYMBOL(blk_finish_request
);
2772 * blk_end_bidi_request - Complete a bidi request
2773 * @rq: the request to complete
2774 * @error: %0 for success, < %0 for error
2775 * @nr_bytes: number of bytes to complete @rq
2776 * @bidi_bytes: number of bytes to complete @rq->next_rq
2779 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2780 * Drivers that supports bidi can safely call this member for any
2781 * type of request, bidi or uni. In the later case @bidi_bytes is
2785 * %false - we are done with this request
2786 * %true - still buffers pending for this request
2788 static bool blk_end_bidi_request(struct request
*rq
, int error
,
2789 unsigned int nr_bytes
, unsigned int bidi_bytes
)
2791 struct request_queue
*q
= rq
->q
;
2792 unsigned long flags
;
2794 if (blk_update_bidi_request(rq
, error
, nr_bytes
, bidi_bytes
))
2797 spin_lock_irqsave(q
->queue_lock
, flags
);
2798 blk_finish_request(rq
, error
);
2799 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2805 * __blk_end_bidi_request - Complete a bidi request with queue lock held
2806 * @rq: the request to complete
2807 * @error: %0 for success, < %0 for error
2808 * @nr_bytes: number of bytes to complete @rq
2809 * @bidi_bytes: number of bytes to complete @rq->next_rq
2812 * Identical to blk_end_bidi_request() except that queue lock is
2813 * assumed to be locked on entry and remains so on return.
2816 * %false - we are done with this request
2817 * %true - still buffers pending for this request
2819 bool __blk_end_bidi_request(struct request
*rq
, int error
,
2820 unsigned int nr_bytes
, unsigned int bidi_bytes
)
2822 if (blk_update_bidi_request(rq
, error
, nr_bytes
, bidi_bytes
))
2825 blk_finish_request(rq
, error
);
2831 * blk_end_request - Helper function for drivers to complete the request.
2832 * @rq: the request being processed
2833 * @error: %0 for success, < %0 for error
2834 * @nr_bytes: number of bytes to complete
2837 * Ends I/O on a number of bytes attached to @rq.
2838 * If @rq has leftover, sets it up for the next range of segments.
2841 * %false - we are done with this request
2842 * %true - still buffers pending for this request
2844 bool blk_end_request(struct request
*rq
, int error
, unsigned int nr_bytes
)
2846 return blk_end_bidi_request(rq
, error
, nr_bytes
, 0);
2848 EXPORT_SYMBOL(blk_end_request
);
2851 * blk_end_request_all - Helper function for drives to finish the request.
2852 * @rq: the request to finish
2853 * @error: %0 for success, < %0 for error
2856 * Completely finish @rq.
2858 void blk_end_request_all(struct request
*rq
, int error
)
2861 unsigned int bidi_bytes
= 0;
2863 if (unlikely(blk_bidi_rq(rq
)))
2864 bidi_bytes
= blk_rq_bytes(rq
->next_rq
);
2866 pending
= blk_end_bidi_request(rq
, error
, blk_rq_bytes(rq
), bidi_bytes
);
2869 EXPORT_SYMBOL(blk_end_request_all
);
2872 * blk_end_request_cur - Helper function to finish the current request chunk.
2873 * @rq: the request to finish the current chunk for
2874 * @error: %0 for success, < %0 for error
2877 * Complete the current consecutively mapped chunk from @rq.
2880 * %false - we are done with this request
2881 * %true - still buffers pending for this request
2883 bool blk_end_request_cur(struct request
*rq
, int error
)
2885 return blk_end_request(rq
, error
, blk_rq_cur_bytes(rq
));
2887 EXPORT_SYMBOL(blk_end_request_cur
);
2890 * blk_end_request_err - Finish a request till the next failure boundary.
2891 * @rq: the request to finish till the next failure boundary for
2892 * @error: must be negative errno
2895 * Complete @rq till the next failure boundary.
2898 * %false - we are done with this request
2899 * %true - still buffers pending for this request
2901 bool blk_end_request_err(struct request
*rq
, int error
)
2903 WARN_ON(error
>= 0);
2904 return blk_end_request(rq
, error
, blk_rq_err_bytes(rq
));
2906 EXPORT_SYMBOL_GPL(blk_end_request_err
);
2909 * __blk_end_request - Helper function for drivers to complete the request.
2910 * @rq: the request being processed
2911 * @error: %0 for success, < %0 for error
2912 * @nr_bytes: number of bytes to complete
2915 * Must be called with queue lock held unlike blk_end_request().
2918 * %false - we are done with this request
2919 * %true - still buffers pending for this request
2921 bool __blk_end_request(struct request
*rq
, int error
, unsigned int nr_bytes
)
2923 return __blk_end_bidi_request(rq
, error
, nr_bytes
, 0);
2925 EXPORT_SYMBOL(__blk_end_request
);
2928 * __blk_end_request_all - Helper function for drives to finish the request.
2929 * @rq: the request to finish
2930 * @error: %0 for success, < %0 for error
2933 * Completely finish @rq. Must be called with queue lock held.
2935 void __blk_end_request_all(struct request
*rq
, int error
)
2938 unsigned int bidi_bytes
= 0;
2940 if (unlikely(blk_bidi_rq(rq
)))
2941 bidi_bytes
= blk_rq_bytes(rq
->next_rq
);
2943 pending
= __blk_end_bidi_request(rq
, error
, blk_rq_bytes(rq
), bidi_bytes
);
2946 EXPORT_SYMBOL(__blk_end_request_all
);
2949 * __blk_end_request_cur - Helper function to finish the current request chunk.
2950 * @rq: the request to finish the current chunk for
2951 * @error: %0 for success, < %0 for error
2954 * Complete the current consecutively mapped chunk from @rq. Must
2955 * be called with queue lock held.
2958 * %false - we are done with this request
2959 * %true - still buffers pending for this request
2961 bool __blk_end_request_cur(struct request
*rq
, int error
)
2963 return __blk_end_request(rq
, error
, blk_rq_cur_bytes(rq
));
2965 EXPORT_SYMBOL(__blk_end_request_cur
);
2968 * __blk_end_request_err - Finish a request till the next failure boundary.
2969 * @rq: the request to finish till the next failure boundary for
2970 * @error: must be negative errno
2973 * Complete @rq till the next failure boundary. Must be called
2974 * with queue lock held.
2977 * %false - we are done with this request
2978 * %true - still buffers pending for this request
2980 bool __blk_end_request_err(struct request
*rq
, int error
)
2982 WARN_ON(error
>= 0);
2983 return __blk_end_request(rq
, error
, blk_rq_err_bytes(rq
));
2985 EXPORT_SYMBOL_GPL(__blk_end_request_err
);
2987 void blk_rq_bio_prep(struct request_queue
*q
, struct request
*rq
,
2990 req_set_op(rq
, bio_op(bio
));
2992 if (bio_has_data(bio
))
2993 rq
->nr_phys_segments
= bio_phys_segments(q
, bio
);
2995 rq
->__data_len
= bio
->bi_iter
.bi_size
;
2996 rq
->bio
= rq
->biotail
= bio
;
2999 rq
->rq_disk
= bio
->bi_bdev
->bd_disk
;
3002 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
3004 * rq_flush_dcache_pages - Helper function to flush all pages in a request
3005 * @rq: the request to be flushed
3008 * Flush all pages in @rq.
3010 void rq_flush_dcache_pages(struct request
*rq
)
3012 struct req_iterator iter
;
3013 struct bio_vec bvec
;
3015 rq_for_each_segment(bvec
, rq
, iter
)
3016 flush_dcache_page(bvec
.bv_page
);
3018 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages
);
3022 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
3023 * @q : the queue of the device being checked
3026 * Check if underlying low-level drivers of a device are busy.
3027 * If the drivers want to export their busy state, they must set own
3028 * exporting function using blk_queue_lld_busy() first.
3030 * Basically, this function is used only by request stacking drivers
3031 * to stop dispatching requests to underlying devices when underlying
3032 * devices are busy. This behavior helps more I/O merging on the queue
3033 * of the request stacking driver and prevents I/O throughput regression
3034 * on burst I/O load.
3037 * 0 - Not busy (The request stacking driver should dispatch request)
3038 * 1 - Busy (The request stacking driver should stop dispatching request)
3040 int blk_lld_busy(struct request_queue
*q
)
3043 return q
->lld_busy_fn(q
);
3047 EXPORT_SYMBOL_GPL(blk_lld_busy
);
3050 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
3051 * @rq: the clone request to be cleaned up
3054 * Free all bios in @rq for a cloned request.
3056 void blk_rq_unprep_clone(struct request
*rq
)
3060 while ((bio
= rq
->bio
) != NULL
) {
3061 rq
->bio
= bio
->bi_next
;
3066 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone
);
3069 * Copy attributes of the original request to the clone request.
3070 * The actual data parts (e.g. ->cmd, ->sense) are not copied.
3072 static void __blk_rq_prep_clone(struct request
*dst
, struct request
*src
)
3074 dst
->cpu
= src
->cpu
;
3075 req_set_op_attrs(dst
, req_op(src
),
3076 (src
->cmd_flags
& REQ_CLONE_MASK
) | REQ_NOMERGE
);
3077 dst
->cmd_type
= src
->cmd_type
;
3078 dst
->__sector
= blk_rq_pos(src
);
3079 dst
->__data_len
= blk_rq_bytes(src
);
3080 dst
->nr_phys_segments
= src
->nr_phys_segments
;
3081 dst
->ioprio
= src
->ioprio
;
3082 dst
->extra_len
= src
->extra_len
;
3086 * blk_rq_prep_clone - Helper function to setup clone request
3087 * @rq: the request to be setup
3088 * @rq_src: original request to be cloned
3089 * @bs: bio_set that bios for clone are allocated from
3090 * @gfp_mask: memory allocation mask for bio
3091 * @bio_ctr: setup function to be called for each clone bio.
3092 * Returns %0 for success, non %0 for failure.
3093 * @data: private data to be passed to @bio_ctr
3096 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
3097 * The actual data parts of @rq_src (e.g. ->cmd, ->sense)
3098 * are not copied, and copying such parts is the caller's responsibility.
3099 * Also, pages which the original bios are pointing to are not copied
3100 * and the cloned bios just point same pages.
3101 * So cloned bios must be completed before original bios, which means
3102 * the caller must complete @rq before @rq_src.
3104 int blk_rq_prep_clone(struct request
*rq
, struct request
*rq_src
,
3105 struct bio_set
*bs
, gfp_t gfp_mask
,
3106 int (*bio_ctr
)(struct bio
*, struct bio
*, void *),
3109 struct bio
*bio
, *bio_src
;
3114 __rq_for_each_bio(bio_src
, rq_src
) {
3115 bio
= bio_clone_fast(bio_src
, gfp_mask
, bs
);
3119 if (bio_ctr
&& bio_ctr(bio
, bio_src
, data
))
3123 rq
->biotail
->bi_next
= bio
;
3126 rq
->bio
= rq
->biotail
= bio
;
3129 __blk_rq_prep_clone(rq
, rq_src
);
3136 blk_rq_unprep_clone(rq
);
3140 EXPORT_SYMBOL_GPL(blk_rq_prep_clone
);
3142 int kblockd_schedule_work(struct work_struct
*work
)
3144 return queue_work(kblockd_workqueue
, work
);
3146 EXPORT_SYMBOL(kblockd_schedule_work
);
3148 int kblockd_schedule_delayed_work(struct delayed_work
*dwork
,
3149 unsigned long delay
)
3151 return queue_delayed_work(kblockd_workqueue
, dwork
, delay
);
3153 EXPORT_SYMBOL(kblockd_schedule_delayed_work
);
3155 int kblockd_schedule_delayed_work_on(int cpu
, struct delayed_work
*dwork
,
3156 unsigned long delay
)
3158 return queue_delayed_work_on(cpu
, kblockd_workqueue
, dwork
, delay
);
3160 EXPORT_SYMBOL(kblockd_schedule_delayed_work_on
);
3163 * blk_start_plug - initialize blk_plug and track it inside the task_struct
3164 * @plug: The &struct blk_plug that needs to be initialized
3167 * Tracking blk_plug inside the task_struct will help with auto-flushing the
3168 * pending I/O should the task end up blocking between blk_start_plug() and
3169 * blk_finish_plug(). This is important from a performance perspective, but
3170 * also ensures that we don't deadlock. For instance, if the task is blocking
3171 * for a memory allocation, memory reclaim could end up wanting to free a
3172 * page belonging to that request that is currently residing in our private
3173 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
3174 * this kind of deadlock.
3176 void blk_start_plug(struct blk_plug
*plug
)
3178 struct task_struct
*tsk
= current
;
3181 * If this is a nested plug, don't actually assign it.
3186 INIT_LIST_HEAD(&plug
->list
);
3187 INIT_LIST_HEAD(&plug
->mq_list
);
3188 INIT_LIST_HEAD(&plug
->cb_list
);
3190 * Store ordering should not be needed here, since a potential
3191 * preempt will imply a full memory barrier
3195 EXPORT_SYMBOL(blk_start_plug
);
3197 static int plug_rq_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
3199 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
3200 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
3202 return !(rqa
->q
< rqb
->q
||
3203 (rqa
->q
== rqb
->q
&& blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
3207 * If 'from_schedule' is true, then postpone the dispatch of requests
3208 * until a safe kblockd context. We due this to avoid accidental big
3209 * additional stack usage in driver dispatch, in places where the originally
3210 * plugger did not intend it.
3212 static void queue_unplugged(struct request_queue
*q
, unsigned int depth
,
3214 __releases(q
->queue_lock
)
3216 trace_block_unplug(q
, depth
, !from_schedule
);
3219 blk_run_queue_async(q
);
3222 spin_unlock(q
->queue_lock
);
3225 static void flush_plug_callbacks(struct blk_plug
*plug
, bool from_schedule
)
3227 LIST_HEAD(callbacks
);
3229 while (!list_empty(&plug
->cb_list
)) {
3230 list_splice_init(&plug
->cb_list
, &callbacks
);
3232 while (!list_empty(&callbacks
)) {
3233 struct blk_plug_cb
*cb
= list_first_entry(&callbacks
,
3236 list_del(&cb
->list
);
3237 cb
->callback(cb
, from_schedule
);
3242 struct blk_plug_cb
*blk_check_plugged(blk_plug_cb_fn unplug
, void *data
,
3245 struct blk_plug
*plug
= current
->plug
;
3246 struct blk_plug_cb
*cb
;
3251 list_for_each_entry(cb
, &plug
->cb_list
, list
)
3252 if (cb
->callback
== unplug
&& cb
->data
== data
)
3255 /* Not currently on the callback list */
3256 BUG_ON(size
< sizeof(*cb
));
3257 cb
= kzalloc(size
, GFP_ATOMIC
);
3260 cb
->callback
= unplug
;
3261 list_add(&cb
->list
, &plug
->cb_list
);
3265 EXPORT_SYMBOL(blk_check_plugged
);
3267 void blk_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
3269 struct request_queue
*q
;
3270 unsigned long flags
;
3275 flush_plug_callbacks(plug
, from_schedule
);
3277 if (!list_empty(&plug
->mq_list
))
3278 blk_mq_flush_plug_list(plug
, from_schedule
);
3280 if (list_empty(&plug
->list
))
3283 list_splice_init(&plug
->list
, &list
);
3285 list_sort(NULL
, &list
, plug_rq_cmp
);
3291 * Save and disable interrupts here, to avoid doing it for every
3292 * queue lock we have to take.
3294 local_irq_save(flags
);
3295 while (!list_empty(&list
)) {
3296 rq
= list_entry_rq(list
.next
);
3297 list_del_init(&rq
->queuelist
);
3301 * This drops the queue lock
3304 queue_unplugged(q
, depth
, from_schedule
);
3307 spin_lock(q
->queue_lock
);
3311 * Short-circuit if @q is dead
3313 if (unlikely(blk_queue_dying(q
))) {
3314 __blk_end_request_all(rq
, -ENODEV
);
3319 * rq is already accounted, so use raw insert
3321 if (rq
->cmd_flags
& (REQ_PREFLUSH
| REQ_FUA
))
3322 __elv_add_request(q
, rq
, ELEVATOR_INSERT_FLUSH
);
3324 __elv_add_request(q
, rq
, ELEVATOR_INSERT_SORT_MERGE
);
3330 * This drops the queue lock
3333 queue_unplugged(q
, depth
, from_schedule
);
3335 local_irq_restore(flags
);
3338 void blk_finish_plug(struct blk_plug
*plug
)
3340 if (plug
!= current
->plug
)
3342 blk_flush_plug_list(plug
, false);
3344 current
->plug
= NULL
;
3346 EXPORT_SYMBOL(blk_finish_plug
);
3348 bool blk_poll(struct request_queue
*q
, blk_qc_t cookie
)
3350 struct blk_plug
*plug
;
3353 if (!q
->mq_ops
|| !q
->mq_ops
->poll
|| !blk_qc_t_valid(cookie
) ||
3354 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
3357 plug
= current
->plug
;
3359 blk_flush_plug_list(plug
, false);
3361 state
= current
->state
;
3362 while (!need_resched()) {
3363 unsigned int queue_num
= blk_qc_t_to_queue_num(cookie
);
3364 struct blk_mq_hw_ctx
*hctx
= q
->queue_hw_ctx
[queue_num
];
3367 hctx
->poll_invoked
++;
3369 ret
= q
->mq_ops
->poll(hctx
, blk_qc_t_to_tag(cookie
));
3371 hctx
->poll_success
++;
3372 set_current_state(TASK_RUNNING
);
3376 if (signal_pending_state(state
, current
))
3377 set_current_state(TASK_RUNNING
);
3379 if (current
->state
== TASK_RUNNING
)
3391 * blk_pm_runtime_init - Block layer runtime PM initialization routine
3392 * @q: the queue of the device
3393 * @dev: the device the queue belongs to
3396 * Initialize runtime-PM-related fields for @q and start auto suspend for
3397 * @dev. Drivers that want to take advantage of request-based runtime PM
3398 * should call this function after @dev has been initialized, and its
3399 * request queue @q has been allocated, and runtime PM for it can not happen
3400 * yet(either due to disabled/forbidden or its usage_count > 0). In most
3401 * cases, driver should call this function before any I/O has taken place.
3403 * This function takes care of setting up using auto suspend for the device,
3404 * the autosuspend delay is set to -1 to make runtime suspend impossible
3405 * until an updated value is either set by user or by driver. Drivers do
3406 * not need to touch other autosuspend settings.
3408 * The block layer runtime PM is request based, so only works for drivers
3409 * that use request as their IO unit instead of those directly use bio's.
3411 void blk_pm_runtime_init(struct request_queue
*q
, struct device
*dev
)
3414 q
->rpm_status
= RPM_ACTIVE
;
3415 pm_runtime_set_autosuspend_delay(q
->dev
, -1);
3416 pm_runtime_use_autosuspend(q
->dev
);
3418 EXPORT_SYMBOL(blk_pm_runtime_init
);
3421 * blk_pre_runtime_suspend - Pre runtime suspend check
3422 * @q: the queue of the device
3425 * This function will check if runtime suspend is allowed for the device
3426 * by examining if there are any requests pending in the queue. If there
3427 * are requests pending, the device can not be runtime suspended; otherwise,
3428 * the queue's status will be updated to SUSPENDING and the driver can
3429 * proceed to suspend the device.
3431 * For the not allowed case, we mark last busy for the device so that
3432 * runtime PM core will try to autosuspend it some time later.
3434 * This function should be called near the start of the device's
3435 * runtime_suspend callback.
3438 * 0 - OK to runtime suspend the device
3439 * -EBUSY - Device should not be runtime suspended
3441 int blk_pre_runtime_suspend(struct request_queue
*q
)
3448 spin_lock_irq(q
->queue_lock
);
3449 if (q
->nr_pending
) {
3451 pm_runtime_mark_last_busy(q
->dev
);
3453 q
->rpm_status
= RPM_SUSPENDING
;
3455 spin_unlock_irq(q
->queue_lock
);
3458 EXPORT_SYMBOL(blk_pre_runtime_suspend
);
3461 * blk_post_runtime_suspend - Post runtime suspend processing
3462 * @q: the queue of the device
3463 * @err: return value of the device's runtime_suspend function
3466 * Update the queue's runtime status according to the return value of the
3467 * device's runtime suspend function and mark last busy for the device so
3468 * that PM core will try to auto suspend the device at a later time.
3470 * This function should be called near the end of the device's
3471 * runtime_suspend callback.
3473 void blk_post_runtime_suspend(struct request_queue
*q
, int err
)
3478 spin_lock_irq(q
->queue_lock
);
3480 q
->rpm_status
= RPM_SUSPENDED
;
3482 q
->rpm_status
= RPM_ACTIVE
;
3483 pm_runtime_mark_last_busy(q
->dev
);
3485 spin_unlock_irq(q
->queue_lock
);
3487 EXPORT_SYMBOL(blk_post_runtime_suspend
);
3490 * blk_pre_runtime_resume - Pre runtime resume processing
3491 * @q: the queue of the device
3494 * Update the queue's runtime status to RESUMING in preparation for the
3495 * runtime resume of the device.
3497 * This function should be called near the start of the device's
3498 * runtime_resume callback.
3500 void blk_pre_runtime_resume(struct request_queue
*q
)
3505 spin_lock_irq(q
->queue_lock
);
3506 q
->rpm_status
= RPM_RESUMING
;
3507 spin_unlock_irq(q
->queue_lock
);
3509 EXPORT_SYMBOL(blk_pre_runtime_resume
);
3512 * blk_post_runtime_resume - Post runtime resume processing
3513 * @q: the queue of the device
3514 * @err: return value of the device's runtime_resume function
3517 * Update the queue's runtime status according to the return value of the
3518 * device's runtime_resume function. If it is successfully resumed, process
3519 * the requests that are queued into the device's queue when it is resuming
3520 * and then mark last busy and initiate autosuspend for it.
3522 * This function should be called near the end of the device's
3523 * runtime_resume callback.
3525 void blk_post_runtime_resume(struct request_queue
*q
, int err
)
3530 spin_lock_irq(q
->queue_lock
);
3532 q
->rpm_status
= RPM_ACTIVE
;
3534 pm_runtime_mark_last_busy(q
->dev
);
3535 pm_request_autosuspend(q
->dev
);
3537 q
->rpm_status
= RPM_SUSPENDED
;
3539 spin_unlock_irq(q
->queue_lock
);
3541 EXPORT_SYMBOL(blk_post_runtime_resume
);
3544 * blk_set_runtime_active - Force runtime status of the queue to be active
3545 * @q: the queue of the device
3547 * If the device is left runtime suspended during system suspend the resume
3548 * hook typically resumes the device and corrects runtime status
3549 * accordingly. However, that does not affect the queue runtime PM status
3550 * which is still "suspended". This prevents processing requests from the
3553 * This function can be used in driver's resume hook to correct queue
3554 * runtime PM status and re-enable peeking requests from the queue. It
3555 * should be called before first request is added to the queue.
3557 void blk_set_runtime_active(struct request_queue
*q
)
3559 spin_lock_irq(q
->queue_lock
);
3560 q
->rpm_status
= RPM_ACTIVE
;
3561 pm_runtime_mark_last_busy(q
->dev
);
3562 pm_request_autosuspend(q
->dev
);
3563 spin_unlock_irq(q
->queue_lock
);
3565 EXPORT_SYMBOL(blk_set_runtime_active
);
3568 int __init
blk_dev_init(void)
3570 BUILD_BUG_ON(__REQ_NR_BITS
> 8 *
3571 FIELD_SIZEOF(struct request
, cmd_flags
));
3573 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
3574 kblockd_workqueue
= alloc_workqueue("kblockd",
3575 WQ_MEM_RECLAIM
| WQ_HIGHPRI
, 0);
3576 if (!kblockd_workqueue
)
3577 panic("Failed to create kblockd\n");
3579 request_cachep
= kmem_cache_create("blkdev_requests",
3580 sizeof(struct request
), 0, SLAB_PANIC
, NULL
);
3582 blk_requestq_cachep
= kmem_cache_create("request_queue",
3583 sizeof(struct request_queue
), 0, SLAB_PANIC
, NULL
);