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>
36 #include <linux/debugfs.h>
37 #include <linux/bpf.h>
39 #define CREATE_TRACE_POINTS
40 #include <trace/events/block.h>
44 #include "blk-mq-sched.h"
46 #include "blk-rq-qos.h"
48 #ifdef CONFIG_DEBUG_FS
49 struct dentry
*blk_debugfs_root
;
52 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap
);
53 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap
);
54 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete
);
55 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split
);
56 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug
);
58 DEFINE_IDA(blk_queue_ida
);
61 * For queue allocation
63 struct kmem_cache
*blk_requestq_cachep
;
66 * Controlling structure to kblockd
68 static struct workqueue_struct
*kblockd_workqueue
;
71 * blk_queue_flag_set - atomically set a queue flag
72 * @flag: flag to be set
75 void blk_queue_flag_set(unsigned int flag
, struct request_queue
*q
)
77 set_bit(flag
, &q
->queue_flags
);
79 EXPORT_SYMBOL(blk_queue_flag_set
);
82 * blk_queue_flag_clear - atomically clear a queue flag
83 * @flag: flag to be cleared
86 void blk_queue_flag_clear(unsigned int flag
, struct request_queue
*q
)
88 clear_bit(flag
, &q
->queue_flags
);
90 EXPORT_SYMBOL(blk_queue_flag_clear
);
93 * blk_queue_flag_test_and_set - atomically test and set a queue flag
94 * @flag: flag to be set
97 * Returns the previous value of @flag - 0 if the flag was not set and 1 if
98 * the flag was already set.
100 bool blk_queue_flag_test_and_set(unsigned int flag
, struct request_queue
*q
)
102 return test_and_set_bit(flag
, &q
->queue_flags
);
104 EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set
);
106 void blk_rq_init(struct request_queue
*q
, struct request
*rq
)
108 memset(rq
, 0, sizeof(*rq
));
110 INIT_LIST_HEAD(&rq
->queuelist
);
112 rq
->__sector
= (sector_t
) -1;
113 INIT_HLIST_NODE(&rq
->hash
);
114 RB_CLEAR_NODE(&rq
->rb_node
);
116 rq
->internal_tag
= -1;
117 rq
->start_time_ns
= ktime_get_ns();
120 EXPORT_SYMBOL(blk_rq_init
);
122 static const struct {
126 [BLK_STS_OK
] = { 0, "" },
127 [BLK_STS_NOTSUPP
] = { -EOPNOTSUPP
, "operation not supported" },
128 [BLK_STS_TIMEOUT
] = { -ETIMEDOUT
, "timeout" },
129 [BLK_STS_NOSPC
] = { -ENOSPC
, "critical space allocation" },
130 [BLK_STS_TRANSPORT
] = { -ENOLINK
, "recoverable transport" },
131 [BLK_STS_TARGET
] = { -EREMOTEIO
, "critical target" },
132 [BLK_STS_NEXUS
] = { -EBADE
, "critical nexus" },
133 [BLK_STS_MEDIUM
] = { -ENODATA
, "critical medium" },
134 [BLK_STS_PROTECTION
] = { -EILSEQ
, "protection" },
135 [BLK_STS_RESOURCE
] = { -ENOMEM
, "kernel resource" },
136 [BLK_STS_DEV_RESOURCE
] = { -EBUSY
, "device resource" },
137 [BLK_STS_AGAIN
] = { -EAGAIN
, "nonblocking retry" },
139 /* device mapper special case, should not leak out: */
140 [BLK_STS_DM_REQUEUE
] = { -EREMCHG
, "dm internal retry" },
142 /* everything else not covered above: */
143 [BLK_STS_IOERR
] = { -EIO
, "I/O" },
146 blk_status_t
errno_to_blk_status(int errno
)
150 for (i
= 0; i
< ARRAY_SIZE(blk_errors
); i
++) {
151 if (blk_errors
[i
].errno
== errno
)
152 return (__force blk_status_t
)i
;
155 return BLK_STS_IOERR
;
157 EXPORT_SYMBOL_GPL(errno_to_blk_status
);
159 int blk_status_to_errno(blk_status_t status
)
161 int idx
= (__force
int)status
;
163 if (WARN_ON_ONCE(idx
>= ARRAY_SIZE(blk_errors
)))
165 return blk_errors
[idx
].errno
;
167 EXPORT_SYMBOL_GPL(blk_status_to_errno
);
169 static void print_req_error(struct request
*req
, blk_status_t status
)
171 int idx
= (__force
int)status
;
173 if (WARN_ON_ONCE(idx
>= ARRAY_SIZE(blk_errors
)))
176 printk_ratelimited(KERN_ERR
"%s: %s error, dev %s, sector %llu flags %x\n",
177 __func__
, blk_errors
[idx
].name
,
178 req
->rq_disk
? req
->rq_disk
->disk_name
: "?",
179 (unsigned long long)blk_rq_pos(req
),
183 static void req_bio_endio(struct request
*rq
, struct bio
*bio
,
184 unsigned int nbytes
, blk_status_t error
)
187 bio
->bi_status
= error
;
189 if (unlikely(rq
->rq_flags
& RQF_QUIET
))
190 bio_set_flag(bio
, BIO_QUIET
);
192 bio_advance(bio
, nbytes
);
194 /* don't actually finish bio if it's part of flush sequence */
195 if (bio
->bi_iter
.bi_size
== 0 && !(rq
->rq_flags
& RQF_FLUSH_SEQ
))
199 void blk_dump_rq_flags(struct request
*rq
, char *msg
)
201 printk(KERN_INFO
"%s: dev %s: flags=%llx\n", msg
,
202 rq
->rq_disk
? rq
->rq_disk
->disk_name
: "?",
203 (unsigned long long) rq
->cmd_flags
);
205 printk(KERN_INFO
" sector %llu, nr/cnr %u/%u\n",
206 (unsigned long long)blk_rq_pos(rq
),
207 blk_rq_sectors(rq
), blk_rq_cur_sectors(rq
));
208 printk(KERN_INFO
" bio %p, biotail %p, len %u\n",
209 rq
->bio
, rq
->biotail
, blk_rq_bytes(rq
));
211 EXPORT_SYMBOL(blk_dump_rq_flags
);
214 * blk_sync_queue - cancel any pending callbacks on a queue
218 * The block layer may perform asynchronous callback activity
219 * on a queue, such as calling the unplug function after a timeout.
220 * A block device may call blk_sync_queue to ensure that any
221 * such activity is cancelled, thus allowing it to release resources
222 * that the callbacks might use. The caller must already have made sure
223 * that its ->make_request_fn will not re-add plugging prior to calling
226 * This function does not cancel any asynchronous activity arising
227 * out of elevator or throttling code. That would require elevator_exit()
228 * and blkcg_exit_queue() to be called with queue lock initialized.
231 void blk_sync_queue(struct request_queue
*q
)
233 del_timer_sync(&q
->timeout
);
234 cancel_work_sync(&q
->timeout_work
);
236 if (queue_is_mq(q
)) {
237 struct blk_mq_hw_ctx
*hctx
;
240 cancel_delayed_work_sync(&q
->requeue_work
);
241 queue_for_each_hw_ctx(q
, hctx
, i
)
242 cancel_delayed_work_sync(&hctx
->run_work
);
245 EXPORT_SYMBOL(blk_sync_queue
);
248 * blk_set_pm_only - increment pm_only counter
249 * @q: request queue pointer
251 void blk_set_pm_only(struct request_queue
*q
)
253 atomic_inc(&q
->pm_only
);
255 EXPORT_SYMBOL_GPL(blk_set_pm_only
);
257 void blk_clear_pm_only(struct request_queue
*q
)
261 pm_only
= atomic_dec_return(&q
->pm_only
);
262 WARN_ON_ONCE(pm_only
< 0);
264 wake_up_all(&q
->mq_freeze_wq
);
266 EXPORT_SYMBOL_GPL(blk_clear_pm_only
);
268 void blk_put_queue(struct request_queue
*q
)
270 kobject_put(&q
->kobj
);
272 EXPORT_SYMBOL(blk_put_queue
);
274 void blk_set_queue_dying(struct request_queue
*q
)
276 blk_queue_flag_set(QUEUE_FLAG_DYING
, q
);
279 * When queue DYING flag is set, we need to block new req
280 * entering queue, so we call blk_freeze_queue_start() to
281 * prevent I/O from crossing blk_queue_enter().
283 blk_freeze_queue_start(q
);
286 blk_mq_wake_waiters(q
);
288 /* Make blk_queue_enter() reexamine the DYING flag. */
289 wake_up_all(&q
->mq_freeze_wq
);
291 EXPORT_SYMBOL_GPL(blk_set_queue_dying
);
293 /* Unconfigure the I/O scheduler and dissociate from the cgroup controller. */
294 void blk_exit_queue(struct request_queue
*q
)
297 * Since the I/O scheduler exit code may access cgroup information,
298 * perform I/O scheduler exit before disassociating from the block
303 elevator_exit(q
, q
->elevator
);
308 * Remove all references to @q from the block cgroup controller before
309 * restoring @q->queue_lock to avoid that restoring this pointer causes
310 * e.g. blkcg_print_blkgs() to crash.
315 * Since the cgroup code may dereference the @q->backing_dev_info
316 * pointer, only decrease its reference count after having removed the
317 * association with the block cgroup controller.
319 bdi_put(q
->backing_dev_info
);
323 * blk_cleanup_queue - shutdown a request queue
324 * @q: request queue to shutdown
326 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
327 * put it. All future requests will be failed immediately with -ENODEV.
329 void blk_cleanup_queue(struct request_queue
*q
)
331 /* mark @q DYING, no new request or merges will be allowed afterwards */
332 mutex_lock(&q
->sysfs_lock
);
333 blk_set_queue_dying(q
);
335 blk_queue_flag_set(QUEUE_FLAG_NOMERGES
, q
);
336 blk_queue_flag_set(QUEUE_FLAG_NOXMERGES
, q
);
337 blk_queue_flag_set(QUEUE_FLAG_DYING
, q
);
338 mutex_unlock(&q
->sysfs_lock
);
341 * Drain all requests queued before DYING marking. Set DEAD flag to
342 * prevent that q->request_fn() gets invoked after draining finished.
348 blk_queue_flag_set(QUEUE_FLAG_DEAD
, q
);
351 * make sure all in-progress dispatch are completed because
352 * blk_freeze_queue() can only complete all requests, and
353 * dispatch may still be in-progress since we dispatch requests
354 * from more than one contexts.
356 * We rely on driver to deal with the race in case that queue
357 * initialization isn't done.
359 if (queue_is_mq(q
) && blk_queue_init_done(q
))
360 blk_mq_quiesce_queue(q
);
362 /* for synchronous bio-based driver finish in-flight integrity i/o */
363 blk_flush_integrity();
365 /* @q won't process any more request, flush async actions */
366 del_timer_sync(&q
->backing_dev_info
->laptop_mode_wb_timer
);
370 * I/O scheduler exit is only safe after the sysfs scheduler attribute
373 WARN_ON_ONCE(q
->kobj
.state_in_sysfs
);
378 blk_mq_free_queue(q
);
380 percpu_ref_exit(&q
->q_usage_counter
);
382 /* @q is and will stay empty, shutdown and put */
385 EXPORT_SYMBOL(blk_cleanup_queue
);
387 struct request_queue
*blk_alloc_queue(gfp_t gfp_mask
)
389 return blk_alloc_queue_node(gfp_mask
, NUMA_NO_NODE
);
391 EXPORT_SYMBOL(blk_alloc_queue
);
394 * blk_queue_enter() - try to increase q->q_usage_counter
395 * @q: request queue pointer
396 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT
398 int blk_queue_enter(struct request_queue
*q
, blk_mq_req_flags_t flags
)
400 const bool pm
= flags
& BLK_MQ_REQ_PREEMPT
;
403 bool success
= false;
406 if (percpu_ref_tryget_live(&q
->q_usage_counter
)) {
408 * The code that increments the pm_only counter is
409 * responsible for ensuring that that counter is
410 * globally visible before the queue is unfrozen.
412 if (pm
|| !blk_queue_pm_only(q
)) {
415 percpu_ref_put(&q
->q_usage_counter
);
423 if (flags
& BLK_MQ_REQ_NOWAIT
)
427 * read pair of barrier in blk_freeze_queue_start(),
428 * we need to order reading __PERCPU_REF_DEAD flag of
429 * .q_usage_counter and reading .mq_freeze_depth or
430 * queue dying flag, otherwise the following wait may
431 * never return if the two reads are reordered.
435 wait_event(q
->mq_freeze_wq
,
436 (atomic_read(&q
->mq_freeze_depth
) == 0 &&
437 (pm
|| (blk_pm_request_resume(q
),
438 !blk_queue_pm_only(q
)))) ||
440 if (blk_queue_dying(q
))
445 void blk_queue_exit(struct request_queue
*q
)
447 percpu_ref_put(&q
->q_usage_counter
);
450 static void blk_queue_usage_counter_release(struct percpu_ref
*ref
)
452 struct request_queue
*q
=
453 container_of(ref
, struct request_queue
, q_usage_counter
);
455 wake_up_all(&q
->mq_freeze_wq
);
458 static void blk_rq_timed_out_timer(struct timer_list
*t
)
460 struct request_queue
*q
= from_timer(q
, t
, timeout
);
462 kblockd_schedule_work(&q
->timeout_work
);
466 * blk_alloc_queue_node - allocate a request queue
467 * @gfp_mask: memory allocation flags
468 * @node_id: NUMA node to allocate memory from
470 struct request_queue
*blk_alloc_queue_node(gfp_t gfp_mask
, int node_id
)
472 struct request_queue
*q
;
475 q
= kmem_cache_alloc_node(blk_requestq_cachep
,
476 gfp_mask
| __GFP_ZERO
, node_id
);
480 INIT_LIST_HEAD(&q
->queue_head
);
481 q
->last_merge
= NULL
;
483 q
->id
= ida_simple_get(&blk_queue_ida
, 0, 0, gfp_mask
);
487 ret
= bioset_init(&q
->bio_split
, BIO_POOL_SIZE
, 0, BIOSET_NEED_BVECS
);
491 q
->backing_dev_info
= bdi_alloc_node(gfp_mask
, node_id
);
492 if (!q
->backing_dev_info
)
495 q
->stats
= blk_alloc_queue_stats();
499 q
->backing_dev_info
->ra_pages
=
500 (VM_MAX_READAHEAD
* 1024) / PAGE_SIZE
;
501 q
->backing_dev_info
->capabilities
= BDI_CAP_CGROUP_WRITEBACK
;
502 q
->backing_dev_info
->name
= "block";
505 timer_setup(&q
->backing_dev_info
->laptop_mode_wb_timer
,
506 laptop_mode_timer_fn
, 0);
507 timer_setup(&q
->timeout
, blk_rq_timed_out_timer
, 0);
508 INIT_WORK(&q
->timeout_work
, NULL
);
509 INIT_LIST_HEAD(&q
->icq_list
);
510 #ifdef CONFIG_BLK_CGROUP
511 INIT_LIST_HEAD(&q
->blkg_list
);
514 kobject_init(&q
->kobj
, &blk_queue_ktype
);
516 #ifdef CONFIG_BLK_DEV_IO_TRACE
517 mutex_init(&q
->blk_trace_mutex
);
519 mutex_init(&q
->sysfs_lock
);
520 spin_lock_init(&q
->queue_lock
);
522 init_waitqueue_head(&q
->mq_freeze_wq
);
525 * Init percpu_ref in atomic mode so that it's faster to shutdown.
526 * See blk_register_queue() for details.
528 if (percpu_ref_init(&q
->q_usage_counter
,
529 blk_queue_usage_counter_release
,
530 PERCPU_REF_INIT_ATOMIC
, GFP_KERNEL
))
533 if (blkcg_init_queue(q
))
539 percpu_ref_exit(&q
->q_usage_counter
);
541 blk_free_queue_stats(q
->stats
);
543 bdi_put(q
->backing_dev_info
);
545 bioset_exit(&q
->bio_split
);
547 ida_simple_remove(&blk_queue_ida
, q
->id
);
549 kmem_cache_free(blk_requestq_cachep
, q
);
552 EXPORT_SYMBOL(blk_alloc_queue_node
);
554 bool blk_get_queue(struct request_queue
*q
)
556 if (likely(!blk_queue_dying(q
))) {
563 EXPORT_SYMBOL(blk_get_queue
);
566 * blk_get_request - allocate a request
567 * @q: request queue to allocate a request for
568 * @op: operation (REQ_OP_*) and REQ_* flags, e.g. REQ_SYNC.
569 * @flags: BLK_MQ_REQ_* flags, e.g. BLK_MQ_REQ_NOWAIT.
571 struct request
*blk_get_request(struct request_queue
*q
, unsigned int op
,
572 blk_mq_req_flags_t flags
)
576 WARN_ON_ONCE(op
& REQ_NOWAIT
);
577 WARN_ON_ONCE(flags
& ~(BLK_MQ_REQ_NOWAIT
| BLK_MQ_REQ_PREEMPT
));
579 req
= blk_mq_alloc_request(q
, op
, flags
);
580 if (!IS_ERR(req
) && q
->mq_ops
->initialize_rq_fn
)
581 q
->mq_ops
->initialize_rq_fn(req
);
585 EXPORT_SYMBOL(blk_get_request
);
587 void blk_put_request(struct request
*req
)
589 blk_mq_free_request(req
);
591 EXPORT_SYMBOL(blk_put_request
);
593 bool bio_attempt_back_merge(struct request_queue
*q
, struct request
*req
,
596 const int ff
= bio
->bi_opf
& REQ_FAILFAST_MASK
;
598 if (!ll_back_merge_fn(q
, req
, bio
))
601 trace_block_bio_backmerge(q
, req
, bio
);
603 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
604 blk_rq_set_mixed_merge(req
);
606 req
->biotail
->bi_next
= bio
;
608 req
->__data_len
+= bio
->bi_iter
.bi_size
;
610 blk_account_io_start(req
, false);
614 bool bio_attempt_front_merge(struct request_queue
*q
, struct request
*req
,
617 const int ff
= bio
->bi_opf
& REQ_FAILFAST_MASK
;
619 if (!ll_front_merge_fn(q
, req
, bio
))
622 trace_block_bio_frontmerge(q
, req
, bio
);
624 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
625 blk_rq_set_mixed_merge(req
);
627 bio
->bi_next
= req
->bio
;
630 req
->__sector
= bio
->bi_iter
.bi_sector
;
631 req
->__data_len
+= bio
->bi_iter
.bi_size
;
633 blk_account_io_start(req
, false);
637 bool bio_attempt_discard_merge(struct request_queue
*q
, struct request
*req
,
640 unsigned short segments
= blk_rq_nr_discard_segments(req
);
642 if (segments
>= queue_max_discard_segments(q
))
644 if (blk_rq_sectors(req
) + bio_sectors(bio
) >
645 blk_rq_get_max_sectors(req
, blk_rq_pos(req
)))
648 req
->biotail
->bi_next
= bio
;
650 req
->__data_len
+= bio
->bi_iter
.bi_size
;
651 req
->nr_phys_segments
= segments
+ 1;
653 blk_account_io_start(req
, false);
656 req_set_nomerge(q
, req
);
661 * blk_attempt_plug_merge - try to merge with %current's plugged list
662 * @q: request_queue new bio is being queued at
663 * @bio: new bio being queued
664 * @same_queue_rq: pointer to &struct request that gets filled in when
665 * another request associated with @q is found on the plug list
666 * (optional, may be %NULL)
668 * Determine whether @bio being queued on @q can be merged with a request
669 * on %current's plugged list. Returns %true if merge was successful,
672 * Plugging coalesces IOs from the same issuer for the same purpose without
673 * going through @q->queue_lock. As such it's more of an issuing mechanism
674 * than scheduling, and the request, while may have elvpriv data, is not
675 * added on the elevator at this point. In addition, we don't have
676 * reliable access to the elevator outside queue lock. Only check basic
677 * merging parameters without querying the elevator.
679 * Caller must ensure !blk_queue_nomerges(q) beforehand.
681 bool blk_attempt_plug_merge(struct request_queue
*q
, struct bio
*bio
,
682 struct request
**same_queue_rq
)
684 struct blk_plug
*plug
;
686 struct list_head
*plug_list
;
688 plug
= current
->plug
;
692 plug_list
= &plug
->mq_list
;
694 list_for_each_entry_reverse(rq
, plug_list
, queuelist
) {
697 if (rq
->q
== q
&& same_queue_rq
) {
699 * Only blk-mq multiple hardware queues case checks the
700 * rq in the same queue, there should be only one such
706 if (rq
->q
!= q
|| !blk_rq_merge_ok(rq
, bio
))
709 switch (blk_try_merge(rq
, bio
)) {
710 case ELEVATOR_BACK_MERGE
:
711 merged
= bio_attempt_back_merge(q
, rq
, bio
);
713 case ELEVATOR_FRONT_MERGE
:
714 merged
= bio_attempt_front_merge(q
, rq
, bio
);
716 case ELEVATOR_DISCARD_MERGE
:
717 merged
= bio_attempt_discard_merge(q
, rq
, bio
);
730 void blk_init_request_from_bio(struct request
*req
, struct bio
*bio
)
732 if (bio
->bi_opf
& REQ_RAHEAD
)
733 req
->cmd_flags
|= REQ_FAILFAST_MASK
;
735 req
->__sector
= bio
->bi_iter
.bi_sector
;
736 req
->ioprio
= bio_prio(bio
);
737 req
->write_hint
= bio
->bi_write_hint
;
738 blk_rq_bio_prep(req
->q
, req
, bio
);
740 EXPORT_SYMBOL_GPL(blk_init_request_from_bio
);
742 static void handle_bad_sector(struct bio
*bio
, sector_t maxsector
)
744 char b
[BDEVNAME_SIZE
];
746 printk(KERN_INFO
"attempt to access beyond end of device\n");
747 printk(KERN_INFO
"%s: rw=%d, want=%Lu, limit=%Lu\n",
748 bio_devname(bio
, b
), bio
->bi_opf
,
749 (unsigned long long)bio_end_sector(bio
),
750 (long long)maxsector
);
753 #ifdef CONFIG_FAIL_MAKE_REQUEST
755 static DECLARE_FAULT_ATTR(fail_make_request
);
757 static int __init
setup_fail_make_request(char *str
)
759 return setup_fault_attr(&fail_make_request
, str
);
761 __setup("fail_make_request=", setup_fail_make_request
);
763 static bool should_fail_request(struct hd_struct
*part
, unsigned int bytes
)
765 return part
->make_it_fail
&& should_fail(&fail_make_request
, bytes
);
768 static int __init
fail_make_request_debugfs(void)
770 struct dentry
*dir
= fault_create_debugfs_attr("fail_make_request",
771 NULL
, &fail_make_request
);
773 return PTR_ERR_OR_ZERO(dir
);
776 late_initcall(fail_make_request_debugfs
);
778 #else /* CONFIG_FAIL_MAKE_REQUEST */
780 static inline bool should_fail_request(struct hd_struct
*part
,
786 #endif /* CONFIG_FAIL_MAKE_REQUEST */
788 static inline bool bio_check_ro(struct bio
*bio
, struct hd_struct
*part
)
790 const int op
= bio_op(bio
);
792 if (part
->policy
&& op_is_write(op
)) {
793 char b
[BDEVNAME_SIZE
];
795 if (op_is_flush(bio
->bi_opf
) && !bio_sectors(bio
))
799 "generic_make_request: Trying to write "
800 "to read-only block-device %s (partno %d)\n",
801 bio_devname(bio
, b
), part
->partno
);
802 /* Older lvm-tools actually trigger this */
809 static noinline
int should_fail_bio(struct bio
*bio
)
811 if (should_fail_request(&bio
->bi_disk
->part0
, bio
->bi_iter
.bi_size
))
815 ALLOW_ERROR_INJECTION(should_fail_bio
, ERRNO
);
818 * Check whether this bio extends beyond the end of the device or partition.
819 * This may well happen - the kernel calls bread() without checking the size of
820 * the device, e.g., when mounting a file system.
822 static inline int bio_check_eod(struct bio
*bio
, sector_t maxsector
)
824 unsigned int nr_sectors
= bio_sectors(bio
);
826 if (nr_sectors
&& maxsector
&&
827 (nr_sectors
> maxsector
||
828 bio
->bi_iter
.bi_sector
> maxsector
- nr_sectors
)) {
829 handle_bad_sector(bio
, maxsector
);
836 * Remap block n of partition p to block n+start(p) of the disk.
838 static inline int blk_partition_remap(struct bio
*bio
)
844 p
= __disk_get_part(bio
->bi_disk
, bio
->bi_partno
);
847 if (unlikely(should_fail_request(p
, bio
->bi_iter
.bi_size
)))
849 if (unlikely(bio_check_ro(bio
, p
)))
853 * Zone reset does not include bi_size so bio_sectors() is always 0.
854 * Include a test for the reset op code and perform the remap if needed.
856 if (bio_sectors(bio
) || bio_op(bio
) == REQ_OP_ZONE_RESET
) {
857 if (bio_check_eod(bio
, part_nr_sects_read(p
)))
859 bio
->bi_iter
.bi_sector
+= p
->start_sect
;
860 trace_block_bio_remap(bio
->bi_disk
->queue
, bio
, part_devt(p
),
861 bio
->bi_iter
.bi_sector
- p
->start_sect
);
870 static noinline_for_stack
bool
871 generic_make_request_checks(struct bio
*bio
)
873 struct request_queue
*q
;
874 int nr_sectors
= bio_sectors(bio
);
875 blk_status_t status
= BLK_STS_IOERR
;
876 char b
[BDEVNAME_SIZE
];
880 q
= bio
->bi_disk
->queue
;
883 "generic_make_request: Trying to access "
884 "nonexistent block-device %s (%Lu)\n",
885 bio_devname(bio
, b
), (long long)bio
->bi_iter
.bi_sector
);
890 * For a REQ_NOWAIT based request, return -EOPNOTSUPP
891 * if queue is not a request based queue.
893 if ((bio
->bi_opf
& REQ_NOWAIT
) && !queue_is_mq(q
))
896 if (should_fail_bio(bio
))
899 if (bio
->bi_partno
) {
900 if (unlikely(blk_partition_remap(bio
)))
903 if (unlikely(bio_check_ro(bio
, &bio
->bi_disk
->part0
)))
905 if (unlikely(bio_check_eod(bio
, get_capacity(bio
->bi_disk
))))
910 * Filter flush bio's early so that make_request based
911 * drivers without flush support don't have to worry
914 if (op_is_flush(bio
->bi_opf
) &&
915 !test_bit(QUEUE_FLAG_WC
, &q
->queue_flags
)) {
916 bio
->bi_opf
&= ~(REQ_PREFLUSH
| REQ_FUA
);
923 if (!test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
924 bio
->bi_opf
&= ~REQ_HIPRI
;
926 switch (bio_op(bio
)) {
928 if (!blk_queue_discard(q
))
931 case REQ_OP_SECURE_ERASE
:
932 if (!blk_queue_secure_erase(q
))
935 case REQ_OP_WRITE_SAME
:
936 if (!q
->limits
.max_write_same_sectors
)
939 case REQ_OP_ZONE_RESET
:
940 if (!blk_queue_is_zoned(q
))
943 case REQ_OP_WRITE_ZEROES
:
944 if (!q
->limits
.max_write_zeroes_sectors
)
952 * Various block parts want %current->io_context and lazy ioc
953 * allocation ends up trading a lot of pain for a small amount of
954 * memory. Just allocate it upfront. This may fail and block
955 * layer knows how to live with it.
957 create_io_context(GFP_ATOMIC
, q
->node
);
959 if (!blkcg_bio_issue_check(q
, bio
))
962 if (!bio_flagged(bio
, BIO_TRACE_COMPLETION
)) {
963 trace_block_bio_queue(q
, bio
);
964 /* Now that enqueuing has been traced, we need to trace
965 * completion as well.
967 bio_set_flag(bio
, BIO_TRACE_COMPLETION
);
972 status
= BLK_STS_NOTSUPP
;
974 bio
->bi_status
= status
;
980 * generic_make_request - hand a buffer to its device driver for I/O
981 * @bio: The bio describing the location in memory and on the device.
983 * generic_make_request() is used to make I/O requests of block
984 * devices. It is passed a &struct bio, which describes the I/O that needs
987 * generic_make_request() does not return any status. The
988 * success/failure status of the request, along with notification of
989 * completion, is delivered asynchronously through the bio->bi_end_io
990 * function described (one day) else where.
992 * The caller of generic_make_request must make sure that bi_io_vec
993 * are set to describe the memory buffer, and that bi_dev and bi_sector are
994 * set to describe the device address, and the
995 * bi_end_io and optionally bi_private are set to describe how
996 * completion notification should be signaled.
998 * generic_make_request and the drivers it calls may use bi_next if this
999 * bio happens to be merged with someone else, and may resubmit the bio to
1000 * a lower device by calling into generic_make_request recursively, which
1001 * means the bio should NOT be touched after the call to ->make_request_fn.
1003 blk_qc_t
generic_make_request(struct bio
*bio
)
1006 * bio_list_on_stack[0] contains bios submitted by the current
1008 * bio_list_on_stack[1] contains bios that were submitted before
1009 * the current make_request_fn, but that haven't been processed
1012 struct bio_list bio_list_on_stack
[2];
1013 blk_mq_req_flags_t flags
= 0;
1014 struct request_queue
*q
= bio
->bi_disk
->queue
;
1015 blk_qc_t ret
= BLK_QC_T_NONE
;
1017 if (bio
->bi_opf
& REQ_NOWAIT
)
1018 flags
= BLK_MQ_REQ_NOWAIT
;
1019 if (bio_flagged(bio
, BIO_QUEUE_ENTERED
))
1020 blk_queue_enter_live(q
);
1021 else if (blk_queue_enter(q
, flags
) < 0) {
1022 if (!blk_queue_dying(q
) && (bio
->bi_opf
& REQ_NOWAIT
))
1023 bio_wouldblock_error(bio
);
1029 if (!generic_make_request_checks(bio
))
1033 * We only want one ->make_request_fn to be active at a time, else
1034 * stack usage with stacked devices could be a problem. So use
1035 * current->bio_list to keep a list of requests submited by a
1036 * make_request_fn function. current->bio_list is also used as a
1037 * flag to say if generic_make_request is currently active in this
1038 * task or not. If it is NULL, then no make_request is active. If
1039 * it is non-NULL, then a make_request is active, and new requests
1040 * should be added at the tail
1042 if (current
->bio_list
) {
1043 bio_list_add(¤t
->bio_list
[0], bio
);
1047 /* following loop may be a bit non-obvious, and so deserves some
1049 * Before entering the loop, bio->bi_next is NULL (as all callers
1050 * ensure that) so we have a list with a single bio.
1051 * We pretend that we have just taken it off a longer list, so
1052 * we assign bio_list to a pointer to the bio_list_on_stack,
1053 * thus initialising the bio_list of new bios to be
1054 * added. ->make_request() may indeed add some more bios
1055 * through a recursive call to generic_make_request. If it
1056 * did, we find a non-NULL value in bio_list and re-enter the loop
1057 * from the top. In this case we really did just take the bio
1058 * of the top of the list (no pretending) and so remove it from
1059 * bio_list, and call into ->make_request() again.
1061 BUG_ON(bio
->bi_next
);
1062 bio_list_init(&bio_list_on_stack
[0]);
1063 current
->bio_list
= bio_list_on_stack
;
1065 bool enter_succeeded
= true;
1067 if (unlikely(q
!= bio
->bi_disk
->queue
)) {
1070 q
= bio
->bi_disk
->queue
;
1072 if (bio
->bi_opf
& REQ_NOWAIT
)
1073 flags
= BLK_MQ_REQ_NOWAIT
;
1074 if (blk_queue_enter(q
, flags
) < 0) {
1075 enter_succeeded
= false;
1080 if (enter_succeeded
) {
1081 struct bio_list lower
, same
;
1083 /* Create a fresh bio_list for all subordinate requests */
1084 bio_list_on_stack
[1] = bio_list_on_stack
[0];
1085 bio_list_init(&bio_list_on_stack
[0]);
1088 * Since we're recursing into make_request here, ensure
1089 * that we mark this bio as already having entered the queue.
1090 * If not, and the queue is going away, we can get stuck
1091 * forever on waiting for the queue reference to drop. But
1092 * that will never happen, as we're already holding a
1095 bio_set_flag(bio
, BIO_QUEUE_ENTERED
);
1096 ret
= q
->make_request_fn(q
, bio
);
1097 bio_clear_flag(bio
, BIO_QUEUE_ENTERED
);
1099 /* sort new bios into those for a lower level
1100 * and those for the same level
1102 bio_list_init(&lower
);
1103 bio_list_init(&same
);
1104 while ((bio
= bio_list_pop(&bio_list_on_stack
[0])) != NULL
)
1105 if (q
== bio
->bi_disk
->queue
)
1106 bio_list_add(&same
, bio
);
1108 bio_list_add(&lower
, bio
);
1109 /* now assemble so we handle the lowest level first */
1110 bio_list_merge(&bio_list_on_stack
[0], &lower
);
1111 bio_list_merge(&bio_list_on_stack
[0], &same
);
1112 bio_list_merge(&bio_list_on_stack
[0], &bio_list_on_stack
[1]);
1114 if (unlikely(!blk_queue_dying(q
) &&
1115 (bio
->bi_opf
& REQ_NOWAIT
)))
1116 bio_wouldblock_error(bio
);
1120 bio
= bio_list_pop(&bio_list_on_stack
[0]);
1122 current
->bio_list
= NULL
; /* deactivate */
1129 EXPORT_SYMBOL(generic_make_request
);
1132 * direct_make_request - hand a buffer directly to its device driver for I/O
1133 * @bio: The bio describing the location in memory and on the device.
1135 * This function behaves like generic_make_request(), but does not protect
1136 * against recursion. Must only be used if the called driver is known
1137 * to not call generic_make_request (or direct_make_request) again from
1138 * its make_request function. (Calling direct_make_request again from
1139 * a workqueue is perfectly fine as that doesn't recurse).
1141 blk_qc_t
direct_make_request(struct bio
*bio
)
1143 struct request_queue
*q
= bio
->bi_disk
->queue
;
1144 bool nowait
= bio
->bi_opf
& REQ_NOWAIT
;
1147 if (!generic_make_request_checks(bio
))
1148 return BLK_QC_T_NONE
;
1150 if (unlikely(blk_queue_enter(q
, nowait
? BLK_MQ_REQ_NOWAIT
: 0))) {
1151 if (nowait
&& !blk_queue_dying(q
))
1152 bio
->bi_status
= BLK_STS_AGAIN
;
1154 bio
->bi_status
= BLK_STS_IOERR
;
1156 return BLK_QC_T_NONE
;
1159 ret
= q
->make_request_fn(q
, bio
);
1163 EXPORT_SYMBOL_GPL(direct_make_request
);
1166 * submit_bio - submit a bio to the block device layer for I/O
1167 * @bio: The &struct bio which describes the I/O
1169 * submit_bio() is very similar in purpose to generic_make_request(), and
1170 * uses that function to do most of the work. Both are fairly rough
1171 * interfaces; @bio must be presetup and ready for I/O.
1174 blk_qc_t
submit_bio(struct bio
*bio
)
1177 * If it's a regular read/write or a barrier with data attached,
1178 * go through the normal accounting stuff before submission.
1180 if (bio_has_data(bio
)) {
1183 if (unlikely(bio_op(bio
) == REQ_OP_WRITE_SAME
))
1184 count
= queue_logical_block_size(bio
->bi_disk
->queue
) >> 9;
1186 count
= bio_sectors(bio
);
1188 if (op_is_write(bio_op(bio
))) {
1189 count_vm_events(PGPGOUT
, count
);
1191 task_io_account_read(bio
->bi_iter
.bi_size
);
1192 count_vm_events(PGPGIN
, count
);
1195 if (unlikely(block_dump
)) {
1196 char b
[BDEVNAME_SIZE
];
1197 printk(KERN_DEBUG
"%s(%d): %s block %Lu on %s (%u sectors)\n",
1198 current
->comm
, task_pid_nr(current
),
1199 op_is_write(bio_op(bio
)) ? "WRITE" : "READ",
1200 (unsigned long long)bio
->bi_iter
.bi_sector
,
1201 bio_devname(bio
, b
), count
);
1205 return generic_make_request(bio
);
1207 EXPORT_SYMBOL(submit_bio
);
1210 * blk_cloned_rq_check_limits - Helper function to check a cloned request
1211 * for new the queue limits
1213 * @rq: the request being checked
1216 * @rq may have been made based on weaker limitations of upper-level queues
1217 * in request stacking drivers, and it may violate the limitation of @q.
1218 * Since the block layer and the underlying device driver trust @rq
1219 * after it is inserted to @q, it should be checked against @q before
1220 * the insertion using this generic function.
1222 * Request stacking drivers like request-based dm may change the queue
1223 * limits when retrying requests on other queues. Those requests need
1224 * to be checked against the new queue limits again during dispatch.
1226 static int blk_cloned_rq_check_limits(struct request_queue
*q
,
1229 if (blk_rq_sectors(rq
) > blk_queue_get_max_sectors(q
, req_op(rq
))) {
1230 printk(KERN_ERR
"%s: over max size limit.\n", __func__
);
1235 * queue's settings related to segment counting like q->bounce_pfn
1236 * may differ from that of other stacking queues.
1237 * Recalculate it to check the request correctly on this queue's
1240 blk_recalc_rq_segments(rq
);
1241 if (rq
->nr_phys_segments
> queue_max_segments(q
)) {
1242 printk(KERN_ERR
"%s: over max segments limit.\n", __func__
);
1250 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
1251 * @q: the queue to submit the request
1252 * @rq: the request being queued
1254 blk_status_t
blk_insert_cloned_request(struct request_queue
*q
, struct request
*rq
)
1258 if (blk_cloned_rq_check_limits(q
, rq
))
1259 return BLK_STS_IOERR
;
1262 should_fail_request(&rq
->rq_disk
->part0
, blk_rq_bytes(rq
)))
1263 return BLK_STS_IOERR
;
1265 if (blk_queue_io_stat(q
))
1266 blk_account_io_start(rq
, true);
1269 * Since we have a scheduler attached on the top device,
1270 * bypass a potential scheduler on the bottom device for
1273 return blk_mq_try_issue_directly(rq
->mq_hctx
, rq
, &unused
, true, true);
1275 EXPORT_SYMBOL_GPL(blk_insert_cloned_request
);
1278 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
1279 * @rq: request to examine
1282 * A request could be merge of IOs which require different failure
1283 * handling. This function determines the number of bytes which
1284 * can be failed from the beginning of the request without
1285 * crossing into area which need to be retried further.
1288 * The number of bytes to fail.
1290 unsigned int blk_rq_err_bytes(const struct request
*rq
)
1292 unsigned int ff
= rq
->cmd_flags
& REQ_FAILFAST_MASK
;
1293 unsigned int bytes
= 0;
1296 if (!(rq
->rq_flags
& RQF_MIXED_MERGE
))
1297 return blk_rq_bytes(rq
);
1300 * Currently the only 'mixing' which can happen is between
1301 * different fastfail types. We can safely fail portions
1302 * which have all the failfast bits that the first one has -
1303 * the ones which are at least as eager to fail as the first
1306 for (bio
= rq
->bio
; bio
; bio
= bio
->bi_next
) {
1307 if ((bio
->bi_opf
& ff
) != ff
)
1309 bytes
+= bio
->bi_iter
.bi_size
;
1312 /* this could lead to infinite loop */
1313 BUG_ON(blk_rq_bytes(rq
) && !bytes
);
1316 EXPORT_SYMBOL_GPL(blk_rq_err_bytes
);
1318 void blk_account_io_completion(struct request
*req
, unsigned int bytes
)
1320 if (blk_do_io_stat(req
)) {
1321 const int sgrp
= op_stat_group(req_op(req
));
1322 struct hd_struct
*part
;
1326 part_stat_add(part
, sectors
[sgrp
], bytes
>> 9);
1331 void blk_account_io_done(struct request
*req
, u64 now
)
1334 * Account IO completion. flush_rq isn't accounted as a
1335 * normal IO on queueing nor completion. Accounting the
1336 * containing request is enough.
1338 if (blk_do_io_stat(req
) && !(req
->rq_flags
& RQF_FLUSH_SEQ
)) {
1339 const int sgrp
= op_stat_group(req_op(req
));
1340 struct hd_struct
*part
;
1345 update_io_ticks(part
, jiffies
);
1346 part_stat_inc(part
, ios
[sgrp
]);
1347 part_stat_add(part
, nsecs
[sgrp
], now
- req
->start_time_ns
);
1348 part_stat_add(part
, time_in_queue
, nsecs_to_jiffies64(now
- req
->start_time_ns
));
1349 part_dec_in_flight(req
->q
, part
, rq_data_dir(req
));
1351 hd_struct_put(part
);
1356 void blk_account_io_start(struct request
*rq
, bool new_io
)
1358 struct hd_struct
*part
;
1359 int rw
= rq_data_dir(rq
);
1361 if (!blk_do_io_stat(rq
))
1368 part_stat_inc(part
, merges
[rw
]);
1370 part
= disk_map_sector_rcu(rq
->rq_disk
, blk_rq_pos(rq
));
1371 if (!hd_struct_try_get(part
)) {
1373 * The partition is already being removed,
1374 * the request will be accounted on the disk only
1376 * We take a reference on disk->part0 although that
1377 * partition will never be deleted, so we can treat
1378 * it as any other partition.
1380 part
= &rq
->rq_disk
->part0
;
1381 hd_struct_get(part
);
1383 part_inc_in_flight(rq
->q
, part
, rw
);
1387 update_io_ticks(part
, jiffies
);
1393 * Steal bios from a request and add them to a bio list.
1394 * The request must not have been partially completed before.
1396 void blk_steal_bios(struct bio_list
*list
, struct request
*rq
)
1400 list
->tail
->bi_next
= rq
->bio
;
1402 list
->head
= rq
->bio
;
1403 list
->tail
= rq
->biotail
;
1411 EXPORT_SYMBOL_GPL(blk_steal_bios
);
1414 * blk_update_request - Special helper function for request stacking drivers
1415 * @req: the request being processed
1416 * @error: block status code
1417 * @nr_bytes: number of bytes to complete @req
1420 * Ends I/O on a number of bytes attached to @req, but doesn't complete
1421 * the request structure even if @req doesn't have leftover.
1422 * If @req has leftover, sets it up for the next range of segments.
1424 * This special helper function is only for request stacking drivers
1425 * (e.g. request-based dm) so that they can handle partial completion.
1426 * Actual device drivers should use blk_end_request instead.
1428 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
1429 * %false return from this function.
1432 * The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in both
1433 * blk_rq_bytes() and in blk_update_request().
1436 * %false - this request doesn't have any more data
1437 * %true - this request has more data
1439 bool blk_update_request(struct request
*req
, blk_status_t error
,
1440 unsigned int nr_bytes
)
1444 trace_block_rq_complete(req
, blk_status_to_errno(error
), nr_bytes
);
1449 if (unlikely(error
&& !blk_rq_is_passthrough(req
) &&
1450 !(req
->rq_flags
& RQF_QUIET
)))
1451 print_req_error(req
, error
);
1453 blk_account_io_completion(req
, nr_bytes
);
1457 struct bio
*bio
= req
->bio
;
1458 unsigned bio_bytes
= min(bio
->bi_iter
.bi_size
, nr_bytes
);
1460 if (bio_bytes
== bio
->bi_iter
.bi_size
)
1461 req
->bio
= bio
->bi_next
;
1463 /* Completion has already been traced */
1464 bio_clear_flag(bio
, BIO_TRACE_COMPLETION
);
1465 req_bio_endio(req
, bio
, bio_bytes
, error
);
1467 total_bytes
+= bio_bytes
;
1468 nr_bytes
-= bio_bytes
;
1479 * Reset counters so that the request stacking driver
1480 * can find how many bytes remain in the request
1483 req
->__data_len
= 0;
1487 req
->__data_len
-= total_bytes
;
1489 /* update sector only for requests with clear definition of sector */
1490 if (!blk_rq_is_passthrough(req
))
1491 req
->__sector
+= total_bytes
>> 9;
1493 /* mixed attributes always follow the first bio */
1494 if (req
->rq_flags
& RQF_MIXED_MERGE
) {
1495 req
->cmd_flags
&= ~REQ_FAILFAST_MASK
;
1496 req
->cmd_flags
|= req
->bio
->bi_opf
& REQ_FAILFAST_MASK
;
1499 if (!(req
->rq_flags
& RQF_SPECIAL_PAYLOAD
)) {
1501 * If total number of sectors is less than the first segment
1502 * size, something has gone terribly wrong.
1504 if (blk_rq_bytes(req
) < blk_rq_cur_bytes(req
)) {
1505 blk_dump_rq_flags(req
, "request botched");
1506 req
->__data_len
= blk_rq_cur_bytes(req
);
1509 /* recalculate the number of segments */
1510 blk_recalc_rq_segments(req
);
1515 EXPORT_SYMBOL_GPL(blk_update_request
);
1517 void blk_rq_bio_prep(struct request_queue
*q
, struct request
*rq
,
1520 if (bio_has_data(bio
))
1521 rq
->nr_phys_segments
= bio_phys_segments(q
, bio
);
1522 else if (bio_op(bio
) == REQ_OP_DISCARD
)
1523 rq
->nr_phys_segments
= 1;
1525 rq
->__data_len
= bio
->bi_iter
.bi_size
;
1526 rq
->bio
= rq
->biotail
= bio
;
1529 rq
->rq_disk
= bio
->bi_disk
;
1532 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
1534 * rq_flush_dcache_pages - Helper function to flush all pages in a request
1535 * @rq: the request to be flushed
1538 * Flush all pages in @rq.
1540 void rq_flush_dcache_pages(struct request
*rq
)
1542 struct req_iterator iter
;
1543 struct bio_vec bvec
;
1545 rq_for_each_segment(bvec
, rq
, iter
)
1546 flush_dcache_page(bvec
.bv_page
);
1548 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages
);
1552 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
1553 * @q : the queue of the device being checked
1556 * Check if underlying low-level drivers of a device are busy.
1557 * If the drivers want to export their busy state, they must set own
1558 * exporting function using blk_queue_lld_busy() first.
1560 * Basically, this function is used only by request stacking drivers
1561 * to stop dispatching requests to underlying devices when underlying
1562 * devices are busy. This behavior helps more I/O merging on the queue
1563 * of the request stacking driver and prevents I/O throughput regression
1564 * on burst I/O load.
1567 * 0 - Not busy (The request stacking driver should dispatch request)
1568 * 1 - Busy (The request stacking driver should stop dispatching request)
1570 int blk_lld_busy(struct request_queue
*q
)
1572 if (queue_is_mq(q
) && q
->mq_ops
->busy
)
1573 return q
->mq_ops
->busy(q
);
1577 EXPORT_SYMBOL_GPL(blk_lld_busy
);
1580 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
1581 * @rq: the clone request to be cleaned up
1584 * Free all bios in @rq for a cloned request.
1586 void blk_rq_unprep_clone(struct request
*rq
)
1590 while ((bio
= rq
->bio
) != NULL
) {
1591 rq
->bio
= bio
->bi_next
;
1596 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone
);
1599 * Copy attributes of the original request to the clone request.
1600 * The actual data parts (e.g. ->cmd, ->sense) are not copied.
1602 static void __blk_rq_prep_clone(struct request
*dst
, struct request
*src
)
1604 dst
->__sector
= blk_rq_pos(src
);
1605 dst
->__data_len
= blk_rq_bytes(src
);
1606 if (src
->rq_flags
& RQF_SPECIAL_PAYLOAD
) {
1607 dst
->rq_flags
|= RQF_SPECIAL_PAYLOAD
;
1608 dst
->special_vec
= src
->special_vec
;
1610 dst
->nr_phys_segments
= src
->nr_phys_segments
;
1611 dst
->ioprio
= src
->ioprio
;
1612 dst
->extra_len
= src
->extra_len
;
1616 * blk_rq_prep_clone - Helper function to setup clone request
1617 * @rq: the request to be setup
1618 * @rq_src: original request to be cloned
1619 * @bs: bio_set that bios for clone are allocated from
1620 * @gfp_mask: memory allocation mask for bio
1621 * @bio_ctr: setup function to be called for each clone bio.
1622 * Returns %0 for success, non %0 for failure.
1623 * @data: private data to be passed to @bio_ctr
1626 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
1627 * The actual data parts of @rq_src (e.g. ->cmd, ->sense)
1628 * are not copied, and copying such parts is the caller's responsibility.
1629 * Also, pages which the original bios are pointing to are not copied
1630 * and the cloned bios just point same pages.
1631 * So cloned bios must be completed before original bios, which means
1632 * the caller must complete @rq before @rq_src.
1634 int blk_rq_prep_clone(struct request
*rq
, struct request
*rq_src
,
1635 struct bio_set
*bs
, gfp_t gfp_mask
,
1636 int (*bio_ctr
)(struct bio
*, struct bio
*, void *),
1639 struct bio
*bio
, *bio_src
;
1644 __rq_for_each_bio(bio_src
, rq_src
) {
1645 bio
= bio_clone_fast(bio_src
, gfp_mask
, bs
);
1649 if (bio_ctr
&& bio_ctr(bio
, bio_src
, data
))
1653 rq
->biotail
->bi_next
= bio
;
1656 rq
->bio
= rq
->biotail
= bio
;
1659 __blk_rq_prep_clone(rq
, rq_src
);
1666 blk_rq_unprep_clone(rq
);
1670 EXPORT_SYMBOL_GPL(blk_rq_prep_clone
);
1672 int kblockd_schedule_work(struct work_struct
*work
)
1674 return queue_work(kblockd_workqueue
, work
);
1676 EXPORT_SYMBOL(kblockd_schedule_work
);
1678 int kblockd_schedule_work_on(int cpu
, struct work_struct
*work
)
1680 return queue_work_on(cpu
, kblockd_workqueue
, work
);
1682 EXPORT_SYMBOL(kblockd_schedule_work_on
);
1684 int kblockd_mod_delayed_work_on(int cpu
, struct delayed_work
*dwork
,
1685 unsigned long delay
)
1687 return mod_delayed_work_on(cpu
, kblockd_workqueue
, dwork
, delay
);
1689 EXPORT_SYMBOL(kblockd_mod_delayed_work_on
);
1692 * blk_start_plug - initialize blk_plug and track it inside the task_struct
1693 * @plug: The &struct blk_plug that needs to be initialized
1696 * blk_start_plug() indicates to the block layer an intent by the caller
1697 * to submit multiple I/O requests in a batch. The block layer may use
1698 * this hint to defer submitting I/Os from the caller until blk_finish_plug()
1699 * is called. However, the block layer may choose to submit requests
1700 * before a call to blk_finish_plug() if the number of queued I/Os
1701 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than
1702 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if
1703 * the task schedules (see below).
1705 * Tracking blk_plug inside the task_struct will help with auto-flushing the
1706 * pending I/O should the task end up blocking between blk_start_plug() and
1707 * blk_finish_plug(). This is important from a performance perspective, but
1708 * also ensures that we don't deadlock. For instance, if the task is blocking
1709 * for a memory allocation, memory reclaim could end up wanting to free a
1710 * page belonging to that request that is currently residing in our private
1711 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
1712 * this kind of deadlock.
1714 void blk_start_plug(struct blk_plug
*plug
)
1716 struct task_struct
*tsk
= current
;
1719 * If this is a nested plug, don't actually assign it.
1724 INIT_LIST_HEAD(&plug
->mq_list
);
1725 INIT_LIST_HEAD(&plug
->cb_list
);
1727 plug
->multiple_queues
= false;
1730 * Store ordering should not be needed here, since a potential
1731 * preempt will imply a full memory barrier
1735 EXPORT_SYMBOL(blk_start_plug
);
1737 static void flush_plug_callbacks(struct blk_plug
*plug
, bool from_schedule
)
1739 LIST_HEAD(callbacks
);
1741 while (!list_empty(&plug
->cb_list
)) {
1742 list_splice_init(&plug
->cb_list
, &callbacks
);
1744 while (!list_empty(&callbacks
)) {
1745 struct blk_plug_cb
*cb
= list_first_entry(&callbacks
,
1748 list_del(&cb
->list
);
1749 cb
->callback(cb
, from_schedule
);
1754 struct blk_plug_cb
*blk_check_plugged(blk_plug_cb_fn unplug
, void *data
,
1757 struct blk_plug
*plug
= current
->plug
;
1758 struct blk_plug_cb
*cb
;
1763 list_for_each_entry(cb
, &plug
->cb_list
, list
)
1764 if (cb
->callback
== unplug
&& cb
->data
== data
)
1767 /* Not currently on the callback list */
1768 BUG_ON(size
< sizeof(*cb
));
1769 cb
= kzalloc(size
, GFP_ATOMIC
);
1772 cb
->callback
= unplug
;
1773 list_add(&cb
->list
, &plug
->cb_list
);
1777 EXPORT_SYMBOL(blk_check_plugged
);
1779 void blk_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1781 flush_plug_callbacks(plug
, from_schedule
);
1783 if (!list_empty(&plug
->mq_list
))
1784 blk_mq_flush_plug_list(plug
, from_schedule
);
1788 * blk_finish_plug - mark the end of a batch of submitted I/O
1789 * @plug: The &struct blk_plug passed to blk_start_plug()
1792 * Indicate that a batch of I/O submissions is complete. This function
1793 * must be paired with an initial call to blk_start_plug(). The intent
1794 * is to allow the block layer to optimize I/O submission. See the
1795 * documentation for blk_start_plug() for more information.
1797 void blk_finish_plug(struct blk_plug
*plug
)
1799 if (plug
!= current
->plug
)
1801 blk_flush_plug_list(plug
, false);
1803 current
->plug
= NULL
;
1805 EXPORT_SYMBOL(blk_finish_plug
);
1807 int __init
blk_dev_init(void)
1809 BUILD_BUG_ON(REQ_OP_LAST
>= (1 << REQ_OP_BITS
));
1810 BUILD_BUG_ON(REQ_OP_BITS
+ REQ_FLAG_BITS
> 8 *
1811 FIELD_SIZEOF(struct request
, cmd_flags
));
1812 BUILD_BUG_ON(REQ_OP_BITS
+ REQ_FLAG_BITS
> 8 *
1813 FIELD_SIZEOF(struct bio
, bi_opf
));
1815 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
1816 kblockd_workqueue
= alloc_workqueue("kblockd",
1817 WQ_MEM_RECLAIM
| WQ_HIGHPRI
, 0);
1818 if (!kblockd_workqueue
)
1819 panic("Failed to create kblockd\n");
1821 blk_requestq_cachep
= kmem_cache_create("request_queue",
1822 sizeof(struct request_queue
), 0, SLAB_PANIC
, NULL
);
1824 #ifdef CONFIG_DEBUG_FS
1825 blk_debugfs_root
= debugfs_create_dir("block", NULL
);