1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright (C) 1994, Karl Keyte: Added support for disk statistics
5 * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
6 * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de>
7 * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au>
9 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
13 * This handles all read/write requests to block devices
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/backing-dev.h>
18 #include <linux/bio.h>
19 #include <linux/blkdev.h>
20 #include <linux/blk-mq.h>
21 #include <linux/highmem.h>
23 #include <linux/kernel_stat.h>
24 #include <linux/string.h>
25 #include <linux/init.h>
26 #include <linux/completion.h>
27 #include <linux/slab.h>
28 #include <linux/swap.h>
29 #include <linux/writeback.h>
30 #include <linux/task_io_accounting_ops.h>
31 #include <linux/fault-inject.h>
32 #include <linux/list_sort.h>
33 #include <linux/delay.h>
34 #include <linux/ratelimit.h>
35 #include <linux/pm_runtime.h>
36 #include <linux/blk-cgroup.h>
37 #include <linux/debugfs.h>
38 #include <linux/bpf.h>
40 #define CREATE_TRACE_POINTS
41 #include <trace/events/block.h>
45 #include "blk-mq-sched.h"
47 #include "blk-rq-qos.h"
49 #ifdef CONFIG_DEBUG_FS
50 struct dentry
*blk_debugfs_root
;
53 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap
);
54 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap
);
55 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete
);
56 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split
);
57 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug
);
59 DEFINE_IDA(blk_queue_ida
);
62 * For queue allocation
64 struct kmem_cache
*blk_requestq_cachep
;
67 * Controlling structure to kblockd
69 static struct workqueue_struct
*kblockd_workqueue
;
72 * blk_queue_flag_set - atomically set a queue flag
73 * @flag: flag to be set
76 void blk_queue_flag_set(unsigned int flag
, struct request_queue
*q
)
78 set_bit(flag
, &q
->queue_flags
);
80 EXPORT_SYMBOL(blk_queue_flag_set
);
83 * blk_queue_flag_clear - atomically clear a queue flag
84 * @flag: flag to be cleared
87 void blk_queue_flag_clear(unsigned int flag
, struct request_queue
*q
)
89 clear_bit(flag
, &q
->queue_flags
);
91 EXPORT_SYMBOL(blk_queue_flag_clear
);
94 * blk_queue_flag_test_and_set - atomically test and set a queue flag
95 * @flag: flag to be set
98 * Returns the previous value of @flag - 0 if the flag was not set and 1 if
99 * the flag was already set.
101 bool blk_queue_flag_test_and_set(unsigned int flag
, struct request_queue
*q
)
103 return test_and_set_bit(flag
, &q
->queue_flags
);
105 EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set
);
107 void blk_rq_init(struct request_queue
*q
, struct request
*rq
)
109 memset(rq
, 0, sizeof(*rq
));
111 INIT_LIST_HEAD(&rq
->queuelist
);
113 rq
->__sector
= (sector_t
) -1;
114 INIT_HLIST_NODE(&rq
->hash
);
115 RB_CLEAR_NODE(&rq
->rb_node
);
117 rq
->internal_tag
= -1;
118 rq
->start_time_ns
= ktime_get_ns();
121 EXPORT_SYMBOL(blk_rq_init
);
123 static const struct {
127 [BLK_STS_OK
] = { 0, "" },
128 [BLK_STS_NOTSUPP
] = { -EOPNOTSUPP
, "operation not supported" },
129 [BLK_STS_TIMEOUT
] = { -ETIMEDOUT
, "timeout" },
130 [BLK_STS_NOSPC
] = { -ENOSPC
, "critical space allocation" },
131 [BLK_STS_TRANSPORT
] = { -ENOLINK
, "recoverable transport" },
132 [BLK_STS_TARGET
] = { -EREMOTEIO
, "critical target" },
133 [BLK_STS_NEXUS
] = { -EBADE
, "critical nexus" },
134 [BLK_STS_MEDIUM
] = { -ENODATA
, "critical medium" },
135 [BLK_STS_PROTECTION
] = { -EILSEQ
, "protection" },
136 [BLK_STS_RESOURCE
] = { -ENOMEM
, "kernel resource" },
137 [BLK_STS_DEV_RESOURCE
] = { -EBUSY
, "device resource" },
138 [BLK_STS_AGAIN
] = { -EAGAIN
, "nonblocking retry" },
140 /* device mapper special case, should not leak out: */
141 [BLK_STS_DM_REQUEUE
] = { -EREMCHG
, "dm internal retry" },
143 /* everything else not covered above: */
144 [BLK_STS_IOERR
] = { -EIO
, "I/O" },
147 blk_status_t
errno_to_blk_status(int errno
)
151 for (i
= 0; i
< ARRAY_SIZE(blk_errors
); i
++) {
152 if (blk_errors
[i
].errno
== errno
)
153 return (__force blk_status_t
)i
;
156 return BLK_STS_IOERR
;
158 EXPORT_SYMBOL_GPL(errno_to_blk_status
);
160 int blk_status_to_errno(blk_status_t status
)
162 int idx
= (__force
int)status
;
164 if (WARN_ON_ONCE(idx
>= ARRAY_SIZE(blk_errors
)))
166 return blk_errors
[idx
].errno
;
168 EXPORT_SYMBOL_GPL(blk_status_to_errno
);
170 static void print_req_error(struct request
*req
, blk_status_t status
)
172 int idx
= (__force
int)status
;
174 if (WARN_ON_ONCE(idx
>= ARRAY_SIZE(blk_errors
)))
177 printk_ratelimited(KERN_ERR
"%s: %s error, dev %s, sector %llu flags %x\n",
178 __func__
, blk_errors
[idx
].name
,
179 req
->rq_disk
? req
->rq_disk
->disk_name
: "?",
180 (unsigned long long)blk_rq_pos(req
),
184 static void req_bio_endio(struct request
*rq
, struct bio
*bio
,
185 unsigned int nbytes
, blk_status_t error
)
188 bio
->bi_status
= error
;
190 if (unlikely(rq
->rq_flags
& RQF_QUIET
))
191 bio_set_flag(bio
, BIO_QUIET
);
193 bio_advance(bio
, nbytes
);
195 /* don't actually finish bio if it's part of flush sequence */
196 if (bio
->bi_iter
.bi_size
== 0 && !(rq
->rq_flags
& RQF_FLUSH_SEQ
))
200 void blk_dump_rq_flags(struct request
*rq
, char *msg
)
202 printk(KERN_INFO
"%s: dev %s: flags=%llx\n", msg
,
203 rq
->rq_disk
? rq
->rq_disk
->disk_name
: "?",
204 (unsigned long long) rq
->cmd_flags
);
206 printk(KERN_INFO
" sector %llu, nr/cnr %u/%u\n",
207 (unsigned long long)blk_rq_pos(rq
),
208 blk_rq_sectors(rq
), blk_rq_cur_sectors(rq
));
209 printk(KERN_INFO
" bio %p, biotail %p, len %u\n",
210 rq
->bio
, rq
->biotail
, blk_rq_bytes(rq
));
212 EXPORT_SYMBOL(blk_dump_rq_flags
);
215 * blk_sync_queue - cancel any pending callbacks on a queue
219 * The block layer may perform asynchronous callback activity
220 * on a queue, such as calling the unplug function after a timeout.
221 * A block device may call blk_sync_queue to ensure that any
222 * such activity is cancelled, thus allowing it to release resources
223 * that the callbacks might use. The caller must already have made sure
224 * that its ->make_request_fn will not re-add plugging prior to calling
227 * This function does not cancel any asynchronous activity arising
228 * out of elevator or throttling code. That would require elevator_exit()
229 * and blkcg_exit_queue() to be called with queue lock initialized.
232 void blk_sync_queue(struct request_queue
*q
)
234 del_timer_sync(&q
->timeout
);
235 cancel_work_sync(&q
->timeout_work
);
237 EXPORT_SYMBOL(blk_sync_queue
);
240 * blk_set_pm_only - increment pm_only counter
241 * @q: request queue pointer
243 void blk_set_pm_only(struct request_queue
*q
)
245 atomic_inc(&q
->pm_only
);
247 EXPORT_SYMBOL_GPL(blk_set_pm_only
);
249 void blk_clear_pm_only(struct request_queue
*q
)
253 pm_only
= atomic_dec_return(&q
->pm_only
);
254 WARN_ON_ONCE(pm_only
< 0);
256 wake_up_all(&q
->mq_freeze_wq
);
258 EXPORT_SYMBOL_GPL(blk_clear_pm_only
);
260 void blk_put_queue(struct request_queue
*q
)
262 kobject_put(&q
->kobj
);
264 EXPORT_SYMBOL(blk_put_queue
);
266 void blk_set_queue_dying(struct request_queue
*q
)
268 blk_queue_flag_set(QUEUE_FLAG_DYING
, q
);
271 * When queue DYING flag is set, we need to block new req
272 * entering queue, so we call blk_freeze_queue_start() to
273 * prevent I/O from crossing blk_queue_enter().
275 blk_freeze_queue_start(q
);
278 blk_mq_wake_waiters(q
);
280 /* Make blk_queue_enter() reexamine the DYING flag. */
281 wake_up_all(&q
->mq_freeze_wq
);
283 EXPORT_SYMBOL_GPL(blk_set_queue_dying
);
286 * blk_cleanup_queue - shutdown a request queue
287 * @q: request queue to shutdown
289 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
290 * put it. All future requests will be failed immediately with -ENODEV.
292 void blk_cleanup_queue(struct request_queue
*q
)
294 /* mark @q DYING, no new request or merges will be allowed afterwards */
295 mutex_lock(&q
->sysfs_lock
);
296 blk_set_queue_dying(q
);
298 blk_queue_flag_set(QUEUE_FLAG_NOMERGES
, q
);
299 blk_queue_flag_set(QUEUE_FLAG_NOXMERGES
, q
);
300 blk_queue_flag_set(QUEUE_FLAG_DYING
, q
);
301 mutex_unlock(&q
->sysfs_lock
);
304 * Drain all requests queued before DYING marking. Set DEAD flag to
305 * prevent that q->request_fn() gets invoked after draining finished.
311 blk_queue_flag_set(QUEUE_FLAG_DEAD
, q
);
313 /* for synchronous bio-based driver finish in-flight integrity i/o */
314 blk_flush_integrity();
316 /* @q won't process any more request, flush async actions */
317 del_timer_sync(&q
->backing_dev_info
->laptop_mode_wb_timer
);
321 blk_mq_exit_queue(q
);
324 * In theory, request pool of sched_tags belongs to request queue.
325 * However, the current implementation requires tag_set for freeing
326 * requests, so free the pool now.
328 * Queue has become frozen, there can't be any in-queue requests, so
329 * it is safe to free requests now.
331 mutex_lock(&q
->sysfs_lock
);
333 blk_mq_sched_free_requests(q
);
334 mutex_unlock(&q
->sysfs_lock
);
336 percpu_ref_exit(&q
->q_usage_counter
);
338 /* @q is and will stay empty, shutdown and put */
341 EXPORT_SYMBOL(blk_cleanup_queue
);
343 struct request_queue
*blk_alloc_queue(gfp_t gfp_mask
)
345 return blk_alloc_queue_node(gfp_mask
, NUMA_NO_NODE
);
347 EXPORT_SYMBOL(blk_alloc_queue
);
350 * blk_queue_enter() - try to increase q->q_usage_counter
351 * @q: request queue pointer
352 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT
354 int blk_queue_enter(struct request_queue
*q
, blk_mq_req_flags_t flags
)
356 const bool pm
= flags
& BLK_MQ_REQ_PREEMPT
;
359 bool success
= false;
362 if (percpu_ref_tryget_live(&q
->q_usage_counter
)) {
364 * The code that increments the pm_only counter is
365 * responsible for ensuring that that counter is
366 * globally visible before the queue is unfrozen.
368 if (pm
|| !blk_queue_pm_only(q
)) {
371 percpu_ref_put(&q
->q_usage_counter
);
379 if (flags
& BLK_MQ_REQ_NOWAIT
)
383 * read pair of barrier in blk_freeze_queue_start(),
384 * we need to order reading __PERCPU_REF_DEAD flag of
385 * .q_usage_counter and reading .mq_freeze_depth or
386 * queue dying flag, otherwise the following wait may
387 * never return if the two reads are reordered.
391 wait_event(q
->mq_freeze_wq
,
392 (!q
->mq_freeze_depth
&&
393 (pm
|| (blk_pm_request_resume(q
),
394 !blk_queue_pm_only(q
)))) ||
396 if (blk_queue_dying(q
))
401 void blk_queue_exit(struct request_queue
*q
)
403 percpu_ref_put(&q
->q_usage_counter
);
406 static void blk_queue_usage_counter_release(struct percpu_ref
*ref
)
408 struct request_queue
*q
=
409 container_of(ref
, struct request_queue
, q_usage_counter
);
411 wake_up_all(&q
->mq_freeze_wq
);
414 static void blk_rq_timed_out_timer(struct timer_list
*t
)
416 struct request_queue
*q
= from_timer(q
, t
, timeout
);
418 kblockd_schedule_work(&q
->timeout_work
);
421 static void blk_timeout_work(struct work_struct
*work
)
426 * blk_alloc_queue_node - allocate a request queue
427 * @gfp_mask: memory allocation flags
428 * @node_id: NUMA node to allocate memory from
430 struct request_queue
*blk_alloc_queue_node(gfp_t gfp_mask
, int node_id
)
432 struct request_queue
*q
;
435 q
= kmem_cache_alloc_node(blk_requestq_cachep
,
436 gfp_mask
| __GFP_ZERO
, node_id
);
440 INIT_LIST_HEAD(&q
->queue_head
);
441 q
->last_merge
= NULL
;
443 q
->id
= ida_simple_get(&blk_queue_ida
, 0, 0, gfp_mask
);
447 ret
= bioset_init(&q
->bio_split
, BIO_POOL_SIZE
, 0, BIOSET_NEED_BVECS
);
451 q
->backing_dev_info
= bdi_alloc_node(gfp_mask
, node_id
);
452 if (!q
->backing_dev_info
)
455 q
->stats
= blk_alloc_queue_stats();
459 q
->backing_dev_info
->ra_pages
= VM_READAHEAD_PAGES
;
460 q
->backing_dev_info
->capabilities
= BDI_CAP_CGROUP_WRITEBACK
;
461 q
->backing_dev_info
->name
= "block";
464 timer_setup(&q
->backing_dev_info
->laptop_mode_wb_timer
,
465 laptop_mode_timer_fn
, 0);
466 timer_setup(&q
->timeout
, blk_rq_timed_out_timer
, 0);
467 INIT_WORK(&q
->timeout_work
, blk_timeout_work
);
468 INIT_LIST_HEAD(&q
->icq_list
);
469 #ifdef CONFIG_BLK_CGROUP
470 INIT_LIST_HEAD(&q
->blkg_list
);
473 kobject_init(&q
->kobj
, &blk_queue_ktype
);
475 #ifdef CONFIG_BLK_DEV_IO_TRACE
476 mutex_init(&q
->blk_trace_mutex
);
478 mutex_init(&q
->sysfs_lock
);
479 spin_lock_init(&q
->queue_lock
);
481 init_waitqueue_head(&q
->mq_freeze_wq
);
482 mutex_init(&q
->mq_freeze_lock
);
485 * Init percpu_ref in atomic mode so that it's faster to shutdown.
486 * See blk_register_queue() for details.
488 if (percpu_ref_init(&q
->q_usage_counter
,
489 blk_queue_usage_counter_release
,
490 PERCPU_REF_INIT_ATOMIC
, GFP_KERNEL
))
493 if (blkcg_init_queue(q
))
499 percpu_ref_exit(&q
->q_usage_counter
);
501 blk_free_queue_stats(q
->stats
);
503 bdi_put(q
->backing_dev_info
);
505 bioset_exit(&q
->bio_split
);
507 ida_simple_remove(&blk_queue_ida
, q
->id
);
509 kmem_cache_free(blk_requestq_cachep
, q
);
512 EXPORT_SYMBOL(blk_alloc_queue_node
);
514 bool blk_get_queue(struct request_queue
*q
)
516 if (likely(!blk_queue_dying(q
))) {
523 EXPORT_SYMBOL(blk_get_queue
);
526 * blk_get_request - allocate a request
527 * @q: request queue to allocate a request for
528 * @op: operation (REQ_OP_*) and REQ_* flags, e.g. REQ_SYNC.
529 * @flags: BLK_MQ_REQ_* flags, e.g. BLK_MQ_REQ_NOWAIT.
531 struct request
*blk_get_request(struct request_queue
*q
, unsigned int op
,
532 blk_mq_req_flags_t flags
)
536 WARN_ON_ONCE(op
& REQ_NOWAIT
);
537 WARN_ON_ONCE(flags
& ~(BLK_MQ_REQ_NOWAIT
| BLK_MQ_REQ_PREEMPT
));
539 req
= blk_mq_alloc_request(q
, op
, flags
);
540 if (!IS_ERR(req
) && q
->mq_ops
->initialize_rq_fn
)
541 q
->mq_ops
->initialize_rq_fn(req
);
545 EXPORT_SYMBOL(blk_get_request
);
547 void blk_put_request(struct request
*req
)
549 blk_mq_free_request(req
);
551 EXPORT_SYMBOL(blk_put_request
);
553 bool bio_attempt_back_merge(struct request_queue
*q
, struct request
*req
,
556 const int ff
= bio
->bi_opf
& REQ_FAILFAST_MASK
;
558 if (!ll_back_merge_fn(q
, req
, bio
))
561 trace_block_bio_backmerge(q
, req
, bio
);
563 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
564 blk_rq_set_mixed_merge(req
);
566 req
->biotail
->bi_next
= bio
;
568 req
->__data_len
+= bio
->bi_iter
.bi_size
;
570 blk_account_io_start(req
, false);
574 bool bio_attempt_front_merge(struct request_queue
*q
, struct request
*req
,
577 const int ff
= bio
->bi_opf
& REQ_FAILFAST_MASK
;
579 if (!ll_front_merge_fn(q
, req
, bio
))
582 trace_block_bio_frontmerge(q
, req
, bio
);
584 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
585 blk_rq_set_mixed_merge(req
);
587 bio
->bi_next
= req
->bio
;
590 req
->__sector
= bio
->bi_iter
.bi_sector
;
591 req
->__data_len
+= bio
->bi_iter
.bi_size
;
593 blk_account_io_start(req
, false);
597 bool bio_attempt_discard_merge(struct request_queue
*q
, struct request
*req
,
600 unsigned short segments
= blk_rq_nr_discard_segments(req
);
602 if (segments
>= queue_max_discard_segments(q
))
604 if (blk_rq_sectors(req
) + bio_sectors(bio
) >
605 blk_rq_get_max_sectors(req
, blk_rq_pos(req
)))
608 req
->biotail
->bi_next
= bio
;
610 req
->__data_len
+= bio
->bi_iter
.bi_size
;
611 req
->nr_phys_segments
= segments
+ 1;
613 blk_account_io_start(req
, false);
616 req_set_nomerge(q
, req
);
621 * blk_attempt_plug_merge - try to merge with %current's plugged list
622 * @q: request_queue new bio is being queued at
623 * @bio: new bio being queued
624 * @same_queue_rq: pointer to &struct request that gets filled in when
625 * another request associated with @q is found on the plug list
626 * (optional, may be %NULL)
628 * Determine whether @bio being queued on @q can be merged with a request
629 * on %current's plugged list. Returns %true if merge was successful,
632 * Plugging coalesces IOs from the same issuer for the same purpose without
633 * going through @q->queue_lock. As such it's more of an issuing mechanism
634 * than scheduling, and the request, while may have elvpriv data, is not
635 * added on the elevator at this point. In addition, we don't have
636 * reliable access to the elevator outside queue lock. Only check basic
637 * merging parameters without querying the elevator.
639 * Caller must ensure !blk_queue_nomerges(q) beforehand.
641 bool blk_attempt_plug_merge(struct request_queue
*q
, struct bio
*bio
,
642 struct request
**same_queue_rq
)
644 struct blk_plug
*plug
;
646 struct list_head
*plug_list
;
648 plug
= current
->plug
;
652 plug_list
= &plug
->mq_list
;
654 list_for_each_entry_reverse(rq
, plug_list
, queuelist
) {
657 if (rq
->q
== q
&& same_queue_rq
) {
659 * Only blk-mq multiple hardware queues case checks the
660 * rq in the same queue, there should be only one such
666 if (rq
->q
!= q
|| !blk_rq_merge_ok(rq
, bio
))
669 switch (blk_try_merge(rq
, bio
)) {
670 case ELEVATOR_BACK_MERGE
:
671 merged
= bio_attempt_back_merge(q
, rq
, bio
);
673 case ELEVATOR_FRONT_MERGE
:
674 merged
= bio_attempt_front_merge(q
, rq
, bio
);
676 case ELEVATOR_DISCARD_MERGE
:
677 merged
= bio_attempt_discard_merge(q
, rq
, bio
);
690 void blk_init_request_from_bio(struct request
*req
, struct bio
*bio
)
692 if (bio
->bi_opf
& REQ_RAHEAD
)
693 req
->cmd_flags
|= REQ_FAILFAST_MASK
;
695 req
->__sector
= bio
->bi_iter
.bi_sector
;
696 req
->ioprio
= bio_prio(bio
);
697 req
->write_hint
= bio
->bi_write_hint
;
698 blk_rq_bio_prep(req
->q
, req
, bio
);
700 EXPORT_SYMBOL_GPL(blk_init_request_from_bio
);
702 static void handle_bad_sector(struct bio
*bio
, sector_t maxsector
)
704 char b
[BDEVNAME_SIZE
];
706 printk(KERN_INFO
"attempt to access beyond end of device\n");
707 printk(KERN_INFO
"%s: rw=%d, want=%Lu, limit=%Lu\n",
708 bio_devname(bio
, b
), bio
->bi_opf
,
709 (unsigned long long)bio_end_sector(bio
),
710 (long long)maxsector
);
713 #ifdef CONFIG_FAIL_MAKE_REQUEST
715 static DECLARE_FAULT_ATTR(fail_make_request
);
717 static int __init
setup_fail_make_request(char *str
)
719 return setup_fault_attr(&fail_make_request
, str
);
721 __setup("fail_make_request=", setup_fail_make_request
);
723 static bool should_fail_request(struct hd_struct
*part
, unsigned int bytes
)
725 return part
->make_it_fail
&& should_fail(&fail_make_request
, bytes
);
728 static int __init
fail_make_request_debugfs(void)
730 struct dentry
*dir
= fault_create_debugfs_attr("fail_make_request",
731 NULL
, &fail_make_request
);
733 return PTR_ERR_OR_ZERO(dir
);
736 late_initcall(fail_make_request_debugfs
);
738 #else /* CONFIG_FAIL_MAKE_REQUEST */
740 static inline bool should_fail_request(struct hd_struct
*part
,
746 #endif /* CONFIG_FAIL_MAKE_REQUEST */
748 static inline bool bio_check_ro(struct bio
*bio
, struct hd_struct
*part
)
750 const int op
= bio_op(bio
);
752 if (part
->policy
&& op_is_write(op
)) {
753 char b
[BDEVNAME_SIZE
];
755 if (op_is_flush(bio
->bi_opf
) && !bio_sectors(bio
))
759 "generic_make_request: Trying to write "
760 "to read-only block-device %s (partno %d)\n",
761 bio_devname(bio
, b
), part
->partno
);
762 /* Older lvm-tools actually trigger this */
769 static noinline
int should_fail_bio(struct bio
*bio
)
771 if (should_fail_request(&bio
->bi_disk
->part0
, bio
->bi_iter
.bi_size
))
775 ALLOW_ERROR_INJECTION(should_fail_bio
, ERRNO
);
778 * Check whether this bio extends beyond the end of the device or partition.
779 * This may well happen - the kernel calls bread() without checking the size of
780 * the device, e.g., when mounting a file system.
782 static inline int bio_check_eod(struct bio
*bio
, sector_t maxsector
)
784 unsigned int nr_sectors
= bio_sectors(bio
);
786 if (nr_sectors
&& maxsector
&&
787 (nr_sectors
> maxsector
||
788 bio
->bi_iter
.bi_sector
> maxsector
- nr_sectors
)) {
789 handle_bad_sector(bio
, maxsector
);
796 * Remap block n of partition p to block n+start(p) of the disk.
798 static inline int blk_partition_remap(struct bio
*bio
)
804 p
= __disk_get_part(bio
->bi_disk
, bio
->bi_partno
);
807 if (unlikely(should_fail_request(p
, bio
->bi_iter
.bi_size
)))
809 if (unlikely(bio_check_ro(bio
, p
)))
813 * Zone reset does not include bi_size so bio_sectors() is always 0.
814 * Include a test for the reset op code and perform the remap if needed.
816 if (bio_sectors(bio
) || bio_op(bio
) == REQ_OP_ZONE_RESET
) {
817 if (bio_check_eod(bio
, part_nr_sects_read(p
)))
819 bio
->bi_iter
.bi_sector
+= p
->start_sect
;
820 trace_block_bio_remap(bio
->bi_disk
->queue
, bio
, part_devt(p
),
821 bio
->bi_iter
.bi_sector
- p
->start_sect
);
830 static noinline_for_stack
bool
831 generic_make_request_checks(struct bio
*bio
)
833 struct request_queue
*q
;
834 int nr_sectors
= bio_sectors(bio
);
835 blk_status_t status
= BLK_STS_IOERR
;
836 char b
[BDEVNAME_SIZE
];
840 q
= bio
->bi_disk
->queue
;
843 "generic_make_request: Trying to access "
844 "nonexistent block-device %s (%Lu)\n",
845 bio_devname(bio
, b
), (long long)bio
->bi_iter
.bi_sector
);
850 * For a REQ_NOWAIT based request, return -EOPNOTSUPP
851 * if queue is not a request based queue.
853 if ((bio
->bi_opf
& REQ_NOWAIT
) && !queue_is_mq(q
))
856 if (should_fail_bio(bio
))
859 if (bio
->bi_partno
) {
860 if (unlikely(blk_partition_remap(bio
)))
863 if (unlikely(bio_check_ro(bio
, &bio
->bi_disk
->part0
)))
865 if (unlikely(bio_check_eod(bio
, get_capacity(bio
->bi_disk
))))
870 * Filter flush bio's early so that make_request based
871 * drivers without flush support don't have to worry
874 if (op_is_flush(bio
->bi_opf
) &&
875 !test_bit(QUEUE_FLAG_WC
, &q
->queue_flags
)) {
876 bio
->bi_opf
&= ~(REQ_PREFLUSH
| REQ_FUA
);
883 if (!test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
884 bio
->bi_opf
&= ~REQ_HIPRI
;
886 switch (bio_op(bio
)) {
888 if (!blk_queue_discard(q
))
891 case REQ_OP_SECURE_ERASE
:
892 if (!blk_queue_secure_erase(q
))
895 case REQ_OP_WRITE_SAME
:
896 if (!q
->limits
.max_write_same_sectors
)
899 case REQ_OP_ZONE_RESET
:
900 if (!blk_queue_is_zoned(q
))
903 case REQ_OP_WRITE_ZEROES
:
904 if (!q
->limits
.max_write_zeroes_sectors
)
912 * Various block parts want %current->io_context and lazy ioc
913 * allocation ends up trading a lot of pain for a small amount of
914 * memory. Just allocate it upfront. This may fail and block
915 * layer knows how to live with it.
917 create_io_context(GFP_ATOMIC
, q
->node
);
919 if (!blkcg_bio_issue_check(q
, bio
))
922 if (!bio_flagged(bio
, BIO_TRACE_COMPLETION
)) {
923 trace_block_bio_queue(q
, bio
);
924 /* Now that enqueuing has been traced, we need to trace
925 * completion as well.
927 bio_set_flag(bio
, BIO_TRACE_COMPLETION
);
932 status
= BLK_STS_NOTSUPP
;
934 bio
->bi_status
= status
;
940 * generic_make_request - hand a buffer to its device driver for I/O
941 * @bio: The bio describing the location in memory and on the device.
943 * generic_make_request() is used to make I/O requests of block
944 * devices. It is passed a &struct bio, which describes the I/O that needs
947 * generic_make_request() does not return any status. The
948 * success/failure status of the request, along with notification of
949 * completion, is delivered asynchronously through the bio->bi_end_io
950 * function described (one day) else where.
952 * The caller of generic_make_request must make sure that bi_io_vec
953 * are set to describe the memory buffer, and that bi_dev and bi_sector are
954 * set to describe the device address, and the
955 * bi_end_io and optionally bi_private are set to describe how
956 * completion notification should be signaled.
958 * generic_make_request and the drivers it calls may use bi_next if this
959 * bio happens to be merged with someone else, and may resubmit the bio to
960 * a lower device by calling into generic_make_request recursively, which
961 * means the bio should NOT be touched after the call to ->make_request_fn.
963 blk_qc_t
generic_make_request(struct bio
*bio
)
966 * bio_list_on_stack[0] contains bios submitted by the current
968 * bio_list_on_stack[1] contains bios that were submitted before
969 * the current make_request_fn, but that haven't been processed
972 struct bio_list bio_list_on_stack
[2];
973 blk_qc_t ret
= BLK_QC_T_NONE
;
975 if (!generic_make_request_checks(bio
))
979 * We only want one ->make_request_fn to be active at a time, else
980 * stack usage with stacked devices could be a problem. So use
981 * current->bio_list to keep a list of requests submited by a
982 * make_request_fn function. current->bio_list is also used as a
983 * flag to say if generic_make_request is currently active in this
984 * task or not. If it is NULL, then no make_request is active. If
985 * it is non-NULL, then a make_request is active, and new requests
986 * should be added at the tail
988 if (current
->bio_list
) {
989 bio_list_add(¤t
->bio_list
[0], bio
);
993 /* following loop may be a bit non-obvious, and so deserves some
995 * Before entering the loop, bio->bi_next is NULL (as all callers
996 * ensure that) so we have a list with a single bio.
997 * We pretend that we have just taken it off a longer list, so
998 * we assign bio_list to a pointer to the bio_list_on_stack,
999 * thus initialising the bio_list of new bios to be
1000 * added. ->make_request() may indeed add some more bios
1001 * through a recursive call to generic_make_request. If it
1002 * did, we find a non-NULL value in bio_list and re-enter the loop
1003 * from the top. In this case we really did just take the bio
1004 * of the top of the list (no pretending) and so remove it from
1005 * bio_list, and call into ->make_request() again.
1007 BUG_ON(bio
->bi_next
);
1008 bio_list_init(&bio_list_on_stack
[0]);
1009 current
->bio_list
= bio_list_on_stack
;
1011 struct request_queue
*q
= bio
->bi_disk
->queue
;
1012 blk_mq_req_flags_t flags
= bio
->bi_opf
& REQ_NOWAIT
?
1013 BLK_MQ_REQ_NOWAIT
: 0;
1015 if (likely(blk_queue_enter(q
, flags
) == 0)) {
1016 struct bio_list lower
, same
;
1018 /* Create a fresh bio_list for all subordinate requests */
1019 bio_list_on_stack
[1] = bio_list_on_stack
[0];
1020 bio_list_init(&bio_list_on_stack
[0]);
1021 ret
= q
->make_request_fn(q
, bio
);
1025 /* sort new bios into those for a lower level
1026 * and those for the same level
1028 bio_list_init(&lower
);
1029 bio_list_init(&same
);
1030 while ((bio
= bio_list_pop(&bio_list_on_stack
[0])) != NULL
)
1031 if (q
== bio
->bi_disk
->queue
)
1032 bio_list_add(&same
, bio
);
1034 bio_list_add(&lower
, bio
);
1035 /* now assemble so we handle the lowest level first */
1036 bio_list_merge(&bio_list_on_stack
[0], &lower
);
1037 bio_list_merge(&bio_list_on_stack
[0], &same
);
1038 bio_list_merge(&bio_list_on_stack
[0], &bio_list_on_stack
[1]);
1040 if (unlikely(!blk_queue_dying(q
) &&
1041 (bio
->bi_opf
& REQ_NOWAIT
)))
1042 bio_wouldblock_error(bio
);
1046 bio
= bio_list_pop(&bio_list_on_stack
[0]);
1048 current
->bio_list
= NULL
; /* deactivate */
1053 EXPORT_SYMBOL(generic_make_request
);
1056 * direct_make_request - hand a buffer directly to its device driver for I/O
1057 * @bio: The bio describing the location in memory and on the device.
1059 * This function behaves like generic_make_request(), but does not protect
1060 * against recursion. Must only be used if the called driver is known
1061 * to not call generic_make_request (or direct_make_request) again from
1062 * its make_request function. (Calling direct_make_request again from
1063 * a workqueue is perfectly fine as that doesn't recurse).
1065 blk_qc_t
direct_make_request(struct bio
*bio
)
1067 struct request_queue
*q
= bio
->bi_disk
->queue
;
1068 bool nowait
= bio
->bi_opf
& REQ_NOWAIT
;
1071 if (!generic_make_request_checks(bio
))
1072 return BLK_QC_T_NONE
;
1074 if (unlikely(blk_queue_enter(q
, nowait
? BLK_MQ_REQ_NOWAIT
: 0))) {
1075 if (nowait
&& !blk_queue_dying(q
))
1076 bio
->bi_status
= BLK_STS_AGAIN
;
1078 bio
->bi_status
= BLK_STS_IOERR
;
1080 return BLK_QC_T_NONE
;
1083 ret
= q
->make_request_fn(q
, bio
);
1087 EXPORT_SYMBOL_GPL(direct_make_request
);
1090 * submit_bio - submit a bio to the block device layer for I/O
1091 * @bio: The &struct bio which describes the I/O
1093 * submit_bio() is very similar in purpose to generic_make_request(), and
1094 * uses that function to do most of the work. Both are fairly rough
1095 * interfaces; @bio must be presetup and ready for I/O.
1098 blk_qc_t
submit_bio(struct bio
*bio
)
1101 * If it's a regular read/write or a barrier with data attached,
1102 * go through the normal accounting stuff before submission.
1104 if (bio_has_data(bio
)) {
1107 if (unlikely(bio_op(bio
) == REQ_OP_WRITE_SAME
))
1108 count
= queue_logical_block_size(bio
->bi_disk
->queue
) >> 9;
1110 count
= bio_sectors(bio
);
1112 if (op_is_write(bio_op(bio
))) {
1113 count_vm_events(PGPGOUT
, count
);
1115 task_io_account_read(bio
->bi_iter
.bi_size
);
1116 count_vm_events(PGPGIN
, count
);
1119 if (unlikely(block_dump
)) {
1120 char b
[BDEVNAME_SIZE
];
1121 printk(KERN_DEBUG
"%s(%d): %s block %Lu on %s (%u sectors)\n",
1122 current
->comm
, task_pid_nr(current
),
1123 op_is_write(bio_op(bio
)) ? "WRITE" : "READ",
1124 (unsigned long long)bio
->bi_iter
.bi_sector
,
1125 bio_devname(bio
, b
), count
);
1129 return generic_make_request(bio
);
1131 EXPORT_SYMBOL(submit_bio
);
1134 * blk_cloned_rq_check_limits - Helper function to check a cloned request
1135 * for new the queue limits
1137 * @rq: the request being checked
1140 * @rq may have been made based on weaker limitations of upper-level queues
1141 * in request stacking drivers, and it may violate the limitation of @q.
1142 * Since the block layer and the underlying device driver trust @rq
1143 * after it is inserted to @q, it should be checked against @q before
1144 * the insertion using this generic function.
1146 * Request stacking drivers like request-based dm may change the queue
1147 * limits when retrying requests on other queues. Those requests need
1148 * to be checked against the new queue limits again during dispatch.
1150 static int blk_cloned_rq_check_limits(struct request_queue
*q
,
1153 if (blk_rq_sectors(rq
) > blk_queue_get_max_sectors(q
, req_op(rq
))) {
1154 printk(KERN_ERR
"%s: over max size limit. (%u > %u)\n",
1155 __func__
, blk_rq_sectors(rq
),
1156 blk_queue_get_max_sectors(q
, req_op(rq
)));
1161 * queue's settings related to segment counting like q->bounce_pfn
1162 * may differ from that of other stacking queues.
1163 * Recalculate it to check the request correctly on this queue's
1166 blk_recalc_rq_segments(rq
);
1167 if (rq
->nr_phys_segments
> queue_max_segments(q
)) {
1168 printk(KERN_ERR
"%s: over max segments limit. (%hu > %hu)\n",
1169 __func__
, rq
->nr_phys_segments
, queue_max_segments(q
));
1177 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
1178 * @q: the queue to submit the request
1179 * @rq: the request being queued
1181 blk_status_t
blk_insert_cloned_request(struct request_queue
*q
, struct request
*rq
)
1183 if (blk_cloned_rq_check_limits(q
, rq
))
1184 return BLK_STS_IOERR
;
1187 should_fail_request(&rq
->rq_disk
->part0
, blk_rq_bytes(rq
)))
1188 return BLK_STS_IOERR
;
1190 if (blk_queue_io_stat(q
))
1191 blk_account_io_start(rq
, true);
1194 * Since we have a scheduler attached on the top device,
1195 * bypass a potential scheduler on the bottom device for
1198 return blk_mq_request_issue_directly(rq
, true);
1200 EXPORT_SYMBOL_GPL(blk_insert_cloned_request
);
1203 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
1204 * @rq: request to examine
1207 * A request could be merge of IOs which require different failure
1208 * handling. This function determines the number of bytes which
1209 * can be failed from the beginning of the request without
1210 * crossing into area which need to be retried further.
1213 * The number of bytes to fail.
1215 unsigned int blk_rq_err_bytes(const struct request
*rq
)
1217 unsigned int ff
= rq
->cmd_flags
& REQ_FAILFAST_MASK
;
1218 unsigned int bytes
= 0;
1221 if (!(rq
->rq_flags
& RQF_MIXED_MERGE
))
1222 return blk_rq_bytes(rq
);
1225 * Currently the only 'mixing' which can happen is between
1226 * different fastfail types. We can safely fail portions
1227 * which have all the failfast bits that the first one has -
1228 * the ones which are at least as eager to fail as the first
1231 for (bio
= rq
->bio
; bio
; bio
= bio
->bi_next
) {
1232 if ((bio
->bi_opf
& ff
) != ff
)
1234 bytes
+= bio
->bi_iter
.bi_size
;
1237 /* this could lead to infinite loop */
1238 BUG_ON(blk_rq_bytes(rq
) && !bytes
);
1241 EXPORT_SYMBOL_GPL(blk_rq_err_bytes
);
1243 void blk_account_io_completion(struct request
*req
, unsigned int bytes
)
1245 if (blk_do_io_stat(req
)) {
1246 const int sgrp
= op_stat_group(req_op(req
));
1247 struct hd_struct
*part
;
1251 part_stat_add(part
, sectors
[sgrp
], bytes
>> 9);
1256 void blk_account_io_done(struct request
*req
, u64 now
)
1259 * Account IO completion. flush_rq isn't accounted as a
1260 * normal IO on queueing nor completion. Accounting the
1261 * containing request is enough.
1263 if (blk_do_io_stat(req
) && !(req
->rq_flags
& RQF_FLUSH_SEQ
)) {
1264 const int sgrp
= op_stat_group(req_op(req
));
1265 struct hd_struct
*part
;
1270 update_io_ticks(part
, jiffies
);
1271 part_stat_inc(part
, ios
[sgrp
]);
1272 part_stat_add(part
, nsecs
[sgrp
], now
- req
->start_time_ns
);
1273 part_stat_add(part
, time_in_queue
, nsecs_to_jiffies64(now
- req
->start_time_ns
));
1274 part_dec_in_flight(req
->q
, part
, rq_data_dir(req
));
1276 hd_struct_put(part
);
1281 void blk_account_io_start(struct request
*rq
, bool new_io
)
1283 struct hd_struct
*part
;
1284 int rw
= rq_data_dir(rq
);
1286 if (!blk_do_io_stat(rq
))
1293 part_stat_inc(part
, merges
[rw
]);
1295 part
= disk_map_sector_rcu(rq
->rq_disk
, blk_rq_pos(rq
));
1296 if (!hd_struct_try_get(part
)) {
1298 * The partition is already being removed,
1299 * the request will be accounted on the disk only
1301 * We take a reference on disk->part0 although that
1302 * partition will never be deleted, so we can treat
1303 * it as any other partition.
1305 part
= &rq
->rq_disk
->part0
;
1306 hd_struct_get(part
);
1308 part_inc_in_flight(rq
->q
, part
, rw
);
1312 update_io_ticks(part
, jiffies
);
1318 * Steal bios from a request and add them to a bio list.
1319 * The request must not have been partially completed before.
1321 void blk_steal_bios(struct bio_list
*list
, struct request
*rq
)
1325 list
->tail
->bi_next
= rq
->bio
;
1327 list
->head
= rq
->bio
;
1328 list
->tail
= rq
->biotail
;
1336 EXPORT_SYMBOL_GPL(blk_steal_bios
);
1339 * blk_update_request - Special helper function for request stacking drivers
1340 * @req: the request being processed
1341 * @error: block status code
1342 * @nr_bytes: number of bytes to complete @req
1345 * Ends I/O on a number of bytes attached to @req, but doesn't complete
1346 * the request structure even if @req doesn't have leftover.
1347 * If @req has leftover, sets it up for the next range of segments.
1349 * This special helper function is only for request stacking drivers
1350 * (e.g. request-based dm) so that they can handle partial completion.
1351 * Actual device drivers should use blk_end_request instead.
1353 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
1354 * %false return from this function.
1357 * The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in both
1358 * blk_rq_bytes() and in blk_update_request().
1361 * %false - this request doesn't have any more data
1362 * %true - this request has more data
1364 bool blk_update_request(struct request
*req
, blk_status_t error
,
1365 unsigned int nr_bytes
)
1369 trace_block_rq_complete(req
, blk_status_to_errno(error
), nr_bytes
);
1374 if (unlikely(error
&& !blk_rq_is_passthrough(req
) &&
1375 !(req
->rq_flags
& RQF_QUIET
)))
1376 print_req_error(req
, error
);
1378 blk_account_io_completion(req
, nr_bytes
);
1382 struct bio
*bio
= req
->bio
;
1383 unsigned bio_bytes
= min(bio
->bi_iter
.bi_size
, nr_bytes
);
1385 if (bio_bytes
== bio
->bi_iter
.bi_size
)
1386 req
->bio
= bio
->bi_next
;
1388 /* Completion has already been traced */
1389 bio_clear_flag(bio
, BIO_TRACE_COMPLETION
);
1390 req_bio_endio(req
, bio
, bio_bytes
, error
);
1392 total_bytes
+= bio_bytes
;
1393 nr_bytes
-= bio_bytes
;
1404 * Reset counters so that the request stacking driver
1405 * can find how many bytes remain in the request
1408 req
->__data_len
= 0;
1412 req
->__data_len
-= total_bytes
;
1414 /* update sector only for requests with clear definition of sector */
1415 if (!blk_rq_is_passthrough(req
))
1416 req
->__sector
+= total_bytes
>> 9;
1418 /* mixed attributes always follow the first bio */
1419 if (req
->rq_flags
& RQF_MIXED_MERGE
) {
1420 req
->cmd_flags
&= ~REQ_FAILFAST_MASK
;
1421 req
->cmd_flags
|= req
->bio
->bi_opf
& REQ_FAILFAST_MASK
;
1424 if (!(req
->rq_flags
& RQF_SPECIAL_PAYLOAD
)) {
1426 * If total number of sectors is less than the first segment
1427 * size, something has gone terribly wrong.
1429 if (blk_rq_bytes(req
) < blk_rq_cur_bytes(req
)) {
1430 blk_dump_rq_flags(req
, "request botched");
1431 req
->__data_len
= blk_rq_cur_bytes(req
);
1434 /* recalculate the number of segments */
1435 blk_recalc_rq_segments(req
);
1440 EXPORT_SYMBOL_GPL(blk_update_request
);
1442 void blk_rq_bio_prep(struct request_queue
*q
, struct request
*rq
,
1445 if (bio_has_data(bio
))
1446 rq
->nr_phys_segments
= bio_phys_segments(q
, bio
);
1447 else if (bio_op(bio
) == REQ_OP_DISCARD
)
1448 rq
->nr_phys_segments
= 1;
1450 rq
->__data_len
= bio
->bi_iter
.bi_size
;
1451 rq
->bio
= rq
->biotail
= bio
;
1454 rq
->rq_disk
= bio
->bi_disk
;
1457 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
1459 * rq_flush_dcache_pages - Helper function to flush all pages in a request
1460 * @rq: the request to be flushed
1463 * Flush all pages in @rq.
1465 void rq_flush_dcache_pages(struct request
*rq
)
1467 struct req_iterator iter
;
1468 struct bio_vec bvec
;
1470 rq_for_each_segment(bvec
, rq
, iter
)
1471 flush_dcache_page(bvec
.bv_page
);
1473 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages
);
1477 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
1478 * @q : the queue of the device being checked
1481 * Check if underlying low-level drivers of a device are busy.
1482 * If the drivers want to export their busy state, they must set own
1483 * exporting function using blk_queue_lld_busy() first.
1485 * Basically, this function is used only by request stacking drivers
1486 * to stop dispatching requests to underlying devices when underlying
1487 * devices are busy. This behavior helps more I/O merging on the queue
1488 * of the request stacking driver and prevents I/O throughput regression
1489 * on burst I/O load.
1492 * 0 - Not busy (The request stacking driver should dispatch request)
1493 * 1 - Busy (The request stacking driver should stop dispatching request)
1495 int blk_lld_busy(struct request_queue
*q
)
1497 if (queue_is_mq(q
) && q
->mq_ops
->busy
)
1498 return q
->mq_ops
->busy(q
);
1502 EXPORT_SYMBOL_GPL(blk_lld_busy
);
1505 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
1506 * @rq: the clone request to be cleaned up
1509 * Free all bios in @rq for a cloned request.
1511 void blk_rq_unprep_clone(struct request
*rq
)
1515 while ((bio
= rq
->bio
) != NULL
) {
1516 rq
->bio
= bio
->bi_next
;
1521 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone
);
1524 * Copy attributes of the original request to the clone request.
1525 * The actual data parts (e.g. ->cmd, ->sense) are not copied.
1527 static void __blk_rq_prep_clone(struct request
*dst
, struct request
*src
)
1529 dst
->__sector
= blk_rq_pos(src
);
1530 dst
->__data_len
= blk_rq_bytes(src
);
1531 if (src
->rq_flags
& RQF_SPECIAL_PAYLOAD
) {
1532 dst
->rq_flags
|= RQF_SPECIAL_PAYLOAD
;
1533 dst
->special_vec
= src
->special_vec
;
1535 dst
->nr_phys_segments
= src
->nr_phys_segments
;
1536 dst
->ioprio
= src
->ioprio
;
1537 dst
->extra_len
= src
->extra_len
;
1541 * blk_rq_prep_clone - Helper function to setup clone request
1542 * @rq: the request to be setup
1543 * @rq_src: original request to be cloned
1544 * @bs: bio_set that bios for clone are allocated from
1545 * @gfp_mask: memory allocation mask for bio
1546 * @bio_ctr: setup function to be called for each clone bio.
1547 * Returns %0 for success, non %0 for failure.
1548 * @data: private data to be passed to @bio_ctr
1551 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
1552 * The actual data parts of @rq_src (e.g. ->cmd, ->sense)
1553 * are not copied, and copying such parts is the caller's responsibility.
1554 * Also, pages which the original bios are pointing to are not copied
1555 * and the cloned bios just point same pages.
1556 * So cloned bios must be completed before original bios, which means
1557 * the caller must complete @rq before @rq_src.
1559 int blk_rq_prep_clone(struct request
*rq
, struct request
*rq_src
,
1560 struct bio_set
*bs
, gfp_t gfp_mask
,
1561 int (*bio_ctr
)(struct bio
*, struct bio
*, void *),
1564 struct bio
*bio
, *bio_src
;
1569 __rq_for_each_bio(bio_src
, rq_src
) {
1570 bio
= bio_clone_fast(bio_src
, gfp_mask
, bs
);
1574 if (bio_ctr
&& bio_ctr(bio
, bio_src
, data
))
1578 rq
->biotail
->bi_next
= bio
;
1581 rq
->bio
= rq
->biotail
= bio
;
1584 __blk_rq_prep_clone(rq
, rq_src
);
1591 blk_rq_unprep_clone(rq
);
1595 EXPORT_SYMBOL_GPL(blk_rq_prep_clone
);
1597 int kblockd_schedule_work(struct work_struct
*work
)
1599 return queue_work(kblockd_workqueue
, work
);
1601 EXPORT_SYMBOL(kblockd_schedule_work
);
1603 int kblockd_schedule_work_on(int cpu
, struct work_struct
*work
)
1605 return queue_work_on(cpu
, kblockd_workqueue
, work
);
1607 EXPORT_SYMBOL(kblockd_schedule_work_on
);
1609 int kblockd_mod_delayed_work_on(int cpu
, struct delayed_work
*dwork
,
1610 unsigned long delay
)
1612 return mod_delayed_work_on(cpu
, kblockd_workqueue
, dwork
, delay
);
1614 EXPORT_SYMBOL(kblockd_mod_delayed_work_on
);
1617 * blk_start_plug - initialize blk_plug and track it inside the task_struct
1618 * @plug: The &struct blk_plug that needs to be initialized
1621 * blk_start_plug() indicates to the block layer an intent by the caller
1622 * to submit multiple I/O requests in a batch. The block layer may use
1623 * this hint to defer submitting I/Os from the caller until blk_finish_plug()
1624 * is called. However, the block layer may choose to submit requests
1625 * before a call to blk_finish_plug() if the number of queued I/Os
1626 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than
1627 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if
1628 * the task schedules (see below).
1630 * Tracking blk_plug inside the task_struct will help with auto-flushing the
1631 * pending I/O should the task end up blocking between blk_start_plug() and
1632 * blk_finish_plug(). This is important from a performance perspective, but
1633 * also ensures that we don't deadlock. For instance, if the task is blocking
1634 * for a memory allocation, memory reclaim could end up wanting to free a
1635 * page belonging to that request that is currently residing in our private
1636 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
1637 * this kind of deadlock.
1639 void blk_start_plug(struct blk_plug
*plug
)
1641 struct task_struct
*tsk
= current
;
1644 * If this is a nested plug, don't actually assign it.
1649 INIT_LIST_HEAD(&plug
->mq_list
);
1650 INIT_LIST_HEAD(&plug
->cb_list
);
1652 plug
->multiple_queues
= false;
1655 * Store ordering should not be needed here, since a potential
1656 * preempt will imply a full memory barrier
1660 EXPORT_SYMBOL(blk_start_plug
);
1662 static void flush_plug_callbacks(struct blk_plug
*plug
, bool from_schedule
)
1664 LIST_HEAD(callbacks
);
1666 while (!list_empty(&plug
->cb_list
)) {
1667 list_splice_init(&plug
->cb_list
, &callbacks
);
1669 while (!list_empty(&callbacks
)) {
1670 struct blk_plug_cb
*cb
= list_first_entry(&callbacks
,
1673 list_del(&cb
->list
);
1674 cb
->callback(cb
, from_schedule
);
1679 struct blk_plug_cb
*blk_check_plugged(blk_plug_cb_fn unplug
, void *data
,
1682 struct blk_plug
*plug
= current
->plug
;
1683 struct blk_plug_cb
*cb
;
1688 list_for_each_entry(cb
, &plug
->cb_list
, list
)
1689 if (cb
->callback
== unplug
&& cb
->data
== data
)
1692 /* Not currently on the callback list */
1693 BUG_ON(size
< sizeof(*cb
));
1694 cb
= kzalloc(size
, GFP_ATOMIC
);
1697 cb
->callback
= unplug
;
1698 list_add(&cb
->list
, &plug
->cb_list
);
1702 EXPORT_SYMBOL(blk_check_plugged
);
1704 void blk_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1706 flush_plug_callbacks(plug
, from_schedule
);
1708 if (!list_empty(&plug
->mq_list
))
1709 blk_mq_flush_plug_list(plug
, from_schedule
);
1713 * blk_finish_plug - mark the end of a batch of submitted I/O
1714 * @plug: The &struct blk_plug passed to blk_start_plug()
1717 * Indicate that a batch of I/O submissions is complete. This function
1718 * must be paired with an initial call to blk_start_plug(). The intent
1719 * is to allow the block layer to optimize I/O submission. See the
1720 * documentation for blk_start_plug() for more information.
1722 void blk_finish_plug(struct blk_plug
*plug
)
1724 if (plug
!= current
->plug
)
1726 blk_flush_plug_list(plug
, false);
1728 current
->plug
= NULL
;
1730 EXPORT_SYMBOL(blk_finish_plug
);
1732 int __init
blk_dev_init(void)
1734 BUILD_BUG_ON(REQ_OP_LAST
>= (1 << REQ_OP_BITS
));
1735 BUILD_BUG_ON(REQ_OP_BITS
+ REQ_FLAG_BITS
> 8 *
1736 FIELD_SIZEOF(struct request
, cmd_flags
));
1737 BUILD_BUG_ON(REQ_OP_BITS
+ REQ_FLAG_BITS
> 8 *
1738 FIELD_SIZEOF(struct bio
, bi_opf
));
1740 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
1741 kblockd_workqueue
= alloc_workqueue("kblockd",
1742 WQ_MEM_RECLAIM
| WQ_HIGHPRI
, 0);
1743 if (!kblockd_workqueue
)
1744 panic("Failed to create kblockd\n");
1746 blk_requestq_cachep
= kmem_cache_create("request_queue",
1747 sizeof(struct request_queue
), 0, SLAB_PANIC
, NULL
);
1749 #ifdef CONFIG_DEBUG_FS
1750 blk_debugfs_root
= debugfs_create_dir("block", NULL
);