xref: /linux/block/blk-core.c (revision 9b960d8cd6f712cb2c03e2bdd4d5ca058238037f)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
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>
8  *	-  July2000
9  * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
10  */
11 
12 /*
13  * This handles all read/write requests to block devices
14  */
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/bio.h>
18 #include <linux/blkdev.h>
19 #include <linux/blk-pm.h>
20 #include <linux/blk-integrity.h>
21 #include <linux/highmem.h>
22 #include <linux/mm.h>
23 #include <linux/pagemap.h>
24 #include <linux/kernel_stat.h>
25 #include <linux/string.h>
26 #include <linux/init.h>
27 #include <linux/completion.h>
28 #include <linux/slab.h>
29 #include <linux/swap.h>
30 #include <linux/writeback.h>
31 #include <linux/task_io_accounting_ops.h>
32 #include <linux/fault-inject.h>
33 #include <linux/list_sort.h>
34 #include <linux/delay.h>
35 #include <linux/ratelimit.h>
36 #include <linux/pm_runtime.h>
37 #include <linux/t10-pi.h>
38 #include <linux/debugfs.h>
39 #include <linux/bpf.h>
40 #include <linux/part_stat.h>
41 #include <linux/sched/sysctl.h>
42 #include <linux/blk-crypto.h>
43 
44 #define CREATE_TRACE_POINTS
45 #include <trace/events/block.h>
46 
47 #include "blk.h"
48 #include "blk-mq-sched.h"
49 #include "blk-pm.h"
50 #include "blk-cgroup.h"
51 #include "blk-throttle.h"
52 #include "blk-ioprio.h"
53 
54 struct dentry *blk_debugfs_root;
55 
56 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
57 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
58 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
59 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split);
60 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
61 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_insert);
62 
63 static DEFINE_IDA(blk_queue_ida);
64 
65 /*
66  * For queue allocation
67  */
68 static struct kmem_cache *blk_requestq_cachep;
69 
70 /*
71  * Controlling structure to kblockd
72  */
73 static struct workqueue_struct *kblockd_workqueue;
74 
75 /**
76  * blk_queue_flag_set - atomically set a queue flag
77  * @flag: flag to be set
78  * @q: request queue
79  */
blk_queue_flag_set(unsigned int flag,struct request_queue * q)80 void blk_queue_flag_set(unsigned int flag, struct request_queue *q)
81 {
82 	set_bit(flag, &q->queue_flags);
83 }
84 EXPORT_SYMBOL(blk_queue_flag_set);
85 
86 /**
87  * blk_queue_flag_clear - atomically clear a queue flag
88  * @flag: flag to be cleared
89  * @q: request queue
90  */
blk_queue_flag_clear(unsigned int flag,struct request_queue * q)91 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q)
92 {
93 	clear_bit(flag, &q->queue_flags);
94 }
95 EXPORT_SYMBOL(blk_queue_flag_clear);
96 
97 #define REQ_OP_NAME(name) [REQ_OP_##name] = #name
98 static const char *const blk_op_name[] = {
99 	REQ_OP_NAME(READ),
100 	REQ_OP_NAME(WRITE),
101 	REQ_OP_NAME(FLUSH),
102 	REQ_OP_NAME(DISCARD),
103 	REQ_OP_NAME(SECURE_ERASE),
104 	REQ_OP_NAME(ZONE_RESET),
105 	REQ_OP_NAME(ZONE_RESET_ALL),
106 	REQ_OP_NAME(ZONE_OPEN),
107 	REQ_OP_NAME(ZONE_CLOSE),
108 	REQ_OP_NAME(ZONE_FINISH),
109 	REQ_OP_NAME(ZONE_APPEND),
110 	REQ_OP_NAME(WRITE_ZEROES),
111 	REQ_OP_NAME(DRV_IN),
112 	REQ_OP_NAME(DRV_OUT),
113 };
114 #undef REQ_OP_NAME
115 
116 /**
117  * blk_op_str - Return string XXX in the REQ_OP_XXX.
118  * @op: REQ_OP_XXX.
119  *
120  * Description: Centralize block layer function to convert REQ_OP_XXX into
121  * string format. Useful in the debugging and tracing bio or request. For
122  * invalid REQ_OP_XXX it returns string "UNKNOWN".
123  */
blk_op_str(enum req_op op)124 inline const char *blk_op_str(enum req_op op)
125 {
126 	const char *op_str = "UNKNOWN";
127 
128 	if (op < ARRAY_SIZE(blk_op_name) && blk_op_name[op])
129 		op_str = blk_op_name[op];
130 
131 	return op_str;
132 }
133 EXPORT_SYMBOL_GPL(blk_op_str);
134 
135 static const struct {
136 	int		errno;
137 	const char	*name;
138 } blk_errors[] = {
139 	[BLK_STS_OK]		= { 0,		"" },
140 	[BLK_STS_NOTSUPP]	= { -EOPNOTSUPP, "operation not supported" },
141 	[BLK_STS_TIMEOUT]	= { -ETIMEDOUT,	"timeout" },
142 	[BLK_STS_NOSPC]		= { -ENOSPC,	"critical space allocation" },
143 	[BLK_STS_TRANSPORT]	= { -ENOLINK,	"recoverable transport" },
144 	[BLK_STS_TARGET]	= { -EREMOTEIO,	"critical target" },
145 	[BLK_STS_RESV_CONFLICT]	= { -EBADE,	"reservation conflict" },
146 	[BLK_STS_MEDIUM]	= { -ENODATA,	"critical medium" },
147 	[BLK_STS_PROTECTION]	= { -EILSEQ,	"protection" },
148 	[BLK_STS_RESOURCE]	= { -ENOMEM,	"kernel resource" },
149 	[BLK_STS_DEV_RESOURCE]	= { -EBUSY,	"device resource" },
150 	[BLK_STS_AGAIN]		= { -EAGAIN,	"nonblocking retry" },
151 	[BLK_STS_OFFLINE]	= { -ENODEV,	"device offline" },
152 
153 	/* device mapper special case, should not leak out: */
154 	[BLK_STS_DM_REQUEUE]	= { -EREMCHG, "dm internal retry" },
155 
156 	/* zone device specific errors */
157 	[BLK_STS_ZONE_OPEN_RESOURCE]	= { -ETOOMANYREFS, "open zones exceeded" },
158 	[BLK_STS_ZONE_ACTIVE_RESOURCE]	= { -EOVERFLOW, "active zones exceeded" },
159 
160 	/* Command duration limit device-side timeout */
161 	[BLK_STS_DURATION_LIMIT]	= { -ETIME, "duration limit exceeded" },
162 
163 	[BLK_STS_INVAL]		= { -EINVAL,	"invalid" },
164 
165 	/* everything else not covered above: */
166 	[BLK_STS_IOERR]		= { -EIO,	"I/O" },
167 };
168 
errno_to_blk_status(int errno)169 blk_status_t errno_to_blk_status(int errno)
170 {
171 	int i;
172 
173 	for (i = 0; i < ARRAY_SIZE(blk_errors); i++) {
174 		if (blk_errors[i].errno == errno)
175 			return (__force blk_status_t)i;
176 	}
177 
178 	return BLK_STS_IOERR;
179 }
180 EXPORT_SYMBOL_GPL(errno_to_blk_status);
181 
blk_status_to_errno(blk_status_t status)182 int blk_status_to_errno(blk_status_t status)
183 {
184 	int idx = (__force int)status;
185 
186 	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
187 		return -EIO;
188 	return blk_errors[idx].errno;
189 }
190 EXPORT_SYMBOL_GPL(blk_status_to_errno);
191 
blk_status_to_str(blk_status_t status)192 const char *blk_status_to_str(blk_status_t status)
193 {
194 	int idx = (__force int)status;
195 
196 	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
197 		return "<null>";
198 	return blk_errors[idx].name;
199 }
200 EXPORT_SYMBOL_GPL(blk_status_to_str);
201 
202 /**
203  * blk_sync_queue - cancel any pending callbacks on a queue
204  * @q: the queue
205  *
206  * Description:
207  *     The block layer may perform asynchronous callback activity
208  *     on a queue, such as calling the unplug function after a timeout.
209  *     A block device may call blk_sync_queue to ensure that any
210  *     such activity is cancelled, thus allowing it to release resources
211  *     that the callbacks might use. The caller must already have made sure
212  *     that its ->submit_bio will not re-add plugging prior to calling
213  *     this function.
214  *
215  *     This function does not cancel any asynchronous activity arising
216  *     out of elevator or throttling code. That would require elevator_exit()
217  *     and blkcg_exit_queue() to be called with queue lock initialized.
218  *
219  */
blk_sync_queue(struct request_queue * q)220 void blk_sync_queue(struct request_queue *q)
221 {
222 	del_timer_sync(&q->timeout);
223 	cancel_work_sync(&q->timeout_work);
224 }
225 EXPORT_SYMBOL(blk_sync_queue);
226 
227 /**
228  * blk_set_pm_only - increment pm_only counter
229  * @q: request queue pointer
230  */
blk_set_pm_only(struct request_queue * q)231 void blk_set_pm_only(struct request_queue *q)
232 {
233 	atomic_inc(&q->pm_only);
234 }
235 EXPORT_SYMBOL_GPL(blk_set_pm_only);
236 
blk_clear_pm_only(struct request_queue * q)237 void blk_clear_pm_only(struct request_queue *q)
238 {
239 	int pm_only;
240 
241 	pm_only = atomic_dec_return(&q->pm_only);
242 	WARN_ON_ONCE(pm_only < 0);
243 	if (pm_only == 0)
244 		wake_up_all(&q->mq_freeze_wq);
245 }
246 EXPORT_SYMBOL_GPL(blk_clear_pm_only);
247 
blk_free_queue_rcu(struct rcu_head * rcu_head)248 static void blk_free_queue_rcu(struct rcu_head *rcu_head)
249 {
250 	struct request_queue *q = container_of(rcu_head,
251 			struct request_queue, rcu_head);
252 
253 	percpu_ref_exit(&q->q_usage_counter);
254 	kmem_cache_free(blk_requestq_cachep, q);
255 }
256 
blk_free_queue(struct request_queue * q)257 static void blk_free_queue(struct request_queue *q)
258 {
259 	blk_free_queue_stats(q->stats);
260 	if (queue_is_mq(q))
261 		blk_mq_release(q);
262 
263 	ida_free(&blk_queue_ida, q->id);
264 	lockdep_unregister_key(&q->io_lock_cls_key);
265 	lockdep_unregister_key(&q->q_lock_cls_key);
266 	call_rcu(&q->rcu_head, blk_free_queue_rcu);
267 }
268 
269 /**
270  * blk_put_queue - decrement the request_queue refcount
271  * @q: the request_queue structure to decrement the refcount for
272  *
273  * Decrements the refcount of the request_queue and free it when the refcount
274  * reaches 0.
275  */
blk_put_queue(struct request_queue * q)276 void blk_put_queue(struct request_queue *q)
277 {
278 	if (refcount_dec_and_test(&q->refs))
279 		blk_free_queue(q);
280 }
281 EXPORT_SYMBOL(blk_put_queue);
282 
blk_queue_start_drain(struct request_queue * q)283 bool blk_queue_start_drain(struct request_queue *q)
284 {
285 	/*
286 	 * When queue DYING flag is set, we need to block new req
287 	 * entering queue, so we call blk_freeze_queue_start() to
288 	 * prevent I/O from crossing blk_queue_enter().
289 	 */
290 	bool freeze = __blk_freeze_queue_start(q, current);
291 	if (queue_is_mq(q))
292 		blk_mq_wake_waiters(q);
293 	/* Make blk_queue_enter() reexamine the DYING flag. */
294 	wake_up_all(&q->mq_freeze_wq);
295 
296 	return freeze;
297 }
298 
299 /**
300  * blk_queue_enter() - try to increase q->q_usage_counter
301  * @q: request queue pointer
302  * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PM
303  */
blk_queue_enter(struct request_queue * q,blk_mq_req_flags_t flags)304 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags)
305 {
306 	const bool pm = flags & BLK_MQ_REQ_PM;
307 
308 	while (!blk_try_enter_queue(q, pm)) {
309 		if (flags & BLK_MQ_REQ_NOWAIT)
310 			return -EAGAIN;
311 
312 		/*
313 		 * read pair of barrier in blk_freeze_queue_start(), we need to
314 		 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and
315 		 * reading .mq_freeze_depth or queue dying flag, otherwise the
316 		 * following wait may never return if the two reads are
317 		 * reordered.
318 		 */
319 		smp_rmb();
320 		wait_event(q->mq_freeze_wq,
321 			   (!q->mq_freeze_depth &&
322 			    blk_pm_resume_queue(pm, q)) ||
323 			   blk_queue_dying(q));
324 		if (blk_queue_dying(q))
325 			return -ENODEV;
326 	}
327 
328 	rwsem_acquire_read(&q->q_lockdep_map, 0, 0, _RET_IP_);
329 	rwsem_release(&q->q_lockdep_map, _RET_IP_);
330 	return 0;
331 }
332 
__bio_queue_enter(struct request_queue * q,struct bio * bio)333 int __bio_queue_enter(struct request_queue *q, struct bio *bio)
334 {
335 	while (!blk_try_enter_queue(q, false)) {
336 		struct gendisk *disk = bio->bi_bdev->bd_disk;
337 
338 		if (bio->bi_opf & REQ_NOWAIT) {
339 			if (test_bit(GD_DEAD, &disk->state))
340 				goto dead;
341 			bio_wouldblock_error(bio);
342 			return -EAGAIN;
343 		}
344 
345 		/*
346 		 * read pair of barrier in blk_freeze_queue_start(), we need to
347 		 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and
348 		 * reading .mq_freeze_depth or queue dying flag, otherwise the
349 		 * following wait may never return if the two reads are
350 		 * reordered.
351 		 */
352 		smp_rmb();
353 		wait_event(q->mq_freeze_wq,
354 			   (!q->mq_freeze_depth &&
355 			    blk_pm_resume_queue(false, q)) ||
356 			   test_bit(GD_DEAD, &disk->state));
357 		if (test_bit(GD_DEAD, &disk->state))
358 			goto dead;
359 	}
360 
361 	rwsem_acquire_read(&q->io_lockdep_map, 0, 0, _RET_IP_);
362 	rwsem_release(&q->io_lockdep_map, _RET_IP_);
363 	return 0;
364 dead:
365 	bio_io_error(bio);
366 	return -ENODEV;
367 }
368 
blk_queue_exit(struct request_queue * q)369 void blk_queue_exit(struct request_queue *q)
370 {
371 	percpu_ref_put(&q->q_usage_counter);
372 }
373 
blk_queue_usage_counter_release(struct percpu_ref * ref)374 static void blk_queue_usage_counter_release(struct percpu_ref *ref)
375 {
376 	struct request_queue *q =
377 		container_of(ref, struct request_queue, q_usage_counter);
378 
379 	wake_up_all(&q->mq_freeze_wq);
380 }
381 
blk_rq_timed_out_timer(struct timer_list * t)382 static void blk_rq_timed_out_timer(struct timer_list *t)
383 {
384 	struct request_queue *q = from_timer(q, t, timeout);
385 
386 	kblockd_schedule_work(&q->timeout_work);
387 }
388 
blk_timeout_work(struct work_struct * work)389 static void blk_timeout_work(struct work_struct *work)
390 {
391 }
392 
blk_alloc_queue(struct queue_limits * lim,int node_id)393 struct request_queue *blk_alloc_queue(struct queue_limits *lim, int node_id)
394 {
395 	struct request_queue *q;
396 	int error;
397 
398 	q = kmem_cache_alloc_node(blk_requestq_cachep, GFP_KERNEL | __GFP_ZERO,
399 				  node_id);
400 	if (!q)
401 		return ERR_PTR(-ENOMEM);
402 
403 	q->last_merge = NULL;
404 
405 	q->id = ida_alloc(&blk_queue_ida, GFP_KERNEL);
406 	if (q->id < 0) {
407 		error = q->id;
408 		goto fail_q;
409 	}
410 
411 	q->stats = blk_alloc_queue_stats();
412 	if (!q->stats) {
413 		error = -ENOMEM;
414 		goto fail_id;
415 	}
416 
417 	error = blk_set_default_limits(lim);
418 	if (error)
419 		goto fail_stats;
420 	q->limits = *lim;
421 
422 	q->node = node_id;
423 
424 	atomic_set(&q->nr_active_requests_shared_tags, 0);
425 
426 	timer_setup(&q->timeout, blk_rq_timed_out_timer, 0);
427 	INIT_WORK(&q->timeout_work, blk_timeout_work);
428 	INIT_LIST_HEAD(&q->icq_list);
429 
430 	refcount_set(&q->refs, 1);
431 	mutex_init(&q->debugfs_mutex);
432 	mutex_init(&q->elevator_lock);
433 	mutex_init(&q->sysfs_lock);
434 	mutex_init(&q->limits_lock);
435 	mutex_init(&q->rq_qos_mutex);
436 	spin_lock_init(&q->queue_lock);
437 
438 	init_waitqueue_head(&q->mq_freeze_wq);
439 	mutex_init(&q->mq_freeze_lock);
440 
441 	blkg_init_queue(q);
442 
443 	/*
444 	 * Init percpu_ref in atomic mode so that it's faster to shutdown.
445 	 * See blk_register_queue() for details.
446 	 */
447 	error = percpu_ref_init(&q->q_usage_counter,
448 				blk_queue_usage_counter_release,
449 				PERCPU_REF_INIT_ATOMIC, GFP_KERNEL);
450 	if (error)
451 		goto fail_stats;
452 	lockdep_register_key(&q->io_lock_cls_key);
453 	lockdep_register_key(&q->q_lock_cls_key);
454 	lockdep_init_map(&q->io_lockdep_map, "&q->q_usage_counter(io)",
455 			 &q->io_lock_cls_key, 0);
456 	lockdep_init_map(&q->q_lockdep_map, "&q->q_usage_counter(queue)",
457 			 &q->q_lock_cls_key, 0);
458 
459 	/* Teach lockdep about lock ordering (reclaim WRT queue freeze lock). */
460 	fs_reclaim_acquire(GFP_KERNEL);
461 	rwsem_acquire_read(&q->io_lockdep_map, 0, 0, _RET_IP_);
462 	rwsem_release(&q->io_lockdep_map, _RET_IP_);
463 	fs_reclaim_release(GFP_KERNEL);
464 
465 	q->nr_requests = BLKDEV_DEFAULT_RQ;
466 
467 	return q;
468 
469 fail_stats:
470 	blk_free_queue_stats(q->stats);
471 fail_id:
472 	ida_free(&blk_queue_ida, q->id);
473 fail_q:
474 	kmem_cache_free(blk_requestq_cachep, q);
475 	return ERR_PTR(error);
476 }
477 
478 /**
479  * blk_get_queue - increment the request_queue refcount
480  * @q: the request_queue structure to increment the refcount for
481  *
482  * Increment the refcount of the request_queue kobject.
483  *
484  * Context: Any context.
485  */
blk_get_queue(struct request_queue * q)486 bool blk_get_queue(struct request_queue *q)
487 {
488 	if (unlikely(blk_queue_dying(q)))
489 		return false;
490 	refcount_inc(&q->refs);
491 	return true;
492 }
493 EXPORT_SYMBOL(blk_get_queue);
494 
495 #ifdef CONFIG_FAIL_MAKE_REQUEST
496 
497 static DECLARE_FAULT_ATTR(fail_make_request);
498 
setup_fail_make_request(char * str)499 static int __init setup_fail_make_request(char *str)
500 {
501 	return setup_fault_attr(&fail_make_request, str);
502 }
503 __setup("fail_make_request=", setup_fail_make_request);
504 
should_fail_request(struct block_device * part,unsigned int bytes)505 bool should_fail_request(struct block_device *part, unsigned int bytes)
506 {
507 	return bdev_test_flag(part, BD_MAKE_IT_FAIL) &&
508 	       should_fail(&fail_make_request, bytes);
509 }
510 
fail_make_request_debugfs(void)511 static int __init fail_make_request_debugfs(void)
512 {
513 	struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
514 						NULL, &fail_make_request);
515 
516 	return PTR_ERR_OR_ZERO(dir);
517 }
518 
519 late_initcall(fail_make_request_debugfs);
520 #endif /* CONFIG_FAIL_MAKE_REQUEST */
521 
bio_check_ro(struct bio * bio)522 static inline void bio_check_ro(struct bio *bio)
523 {
524 	if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) {
525 		if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
526 			return;
527 
528 		if (bdev_test_flag(bio->bi_bdev, BD_RO_WARNED))
529 			return;
530 
531 		bdev_set_flag(bio->bi_bdev, BD_RO_WARNED);
532 
533 		/*
534 		 * Use ioctl to set underlying disk of raid/dm to read-only
535 		 * will trigger this.
536 		 */
537 		pr_warn("Trying to write to read-only block-device %pg\n",
538 			bio->bi_bdev);
539 	}
540 }
541 
should_fail_bio(struct bio * bio)542 static noinline int should_fail_bio(struct bio *bio)
543 {
544 	if (should_fail_request(bdev_whole(bio->bi_bdev), bio->bi_iter.bi_size))
545 		return -EIO;
546 	return 0;
547 }
548 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO);
549 
550 /*
551  * Check whether this bio extends beyond the end of the device or partition.
552  * This may well happen - the kernel calls bread() without checking the size of
553  * the device, e.g., when mounting a file system.
554  */
bio_check_eod(struct bio * bio)555 static inline int bio_check_eod(struct bio *bio)
556 {
557 	sector_t maxsector = bdev_nr_sectors(bio->bi_bdev);
558 	unsigned int nr_sectors = bio_sectors(bio);
559 
560 	if (nr_sectors &&
561 	    (nr_sectors > maxsector ||
562 	     bio->bi_iter.bi_sector > maxsector - nr_sectors)) {
563 		pr_info_ratelimited("%s: attempt to access beyond end of device\n"
564 				    "%pg: rw=%d, sector=%llu, nr_sectors = %u limit=%llu\n",
565 				    current->comm, bio->bi_bdev, bio->bi_opf,
566 				    bio->bi_iter.bi_sector, nr_sectors, maxsector);
567 		return -EIO;
568 	}
569 	return 0;
570 }
571 
572 /*
573  * Remap block n of partition p to block n+start(p) of the disk.
574  */
blk_partition_remap(struct bio * bio)575 static int blk_partition_remap(struct bio *bio)
576 {
577 	struct block_device *p = bio->bi_bdev;
578 
579 	if (unlikely(should_fail_request(p, bio->bi_iter.bi_size)))
580 		return -EIO;
581 	if (bio_sectors(bio)) {
582 		bio->bi_iter.bi_sector += p->bd_start_sect;
583 		trace_block_bio_remap(bio, p->bd_dev,
584 				      bio->bi_iter.bi_sector -
585 				      p->bd_start_sect);
586 	}
587 	bio_set_flag(bio, BIO_REMAPPED);
588 	return 0;
589 }
590 
591 /*
592  * Check write append to a zoned block device.
593  */
blk_check_zone_append(struct request_queue * q,struct bio * bio)594 static inline blk_status_t blk_check_zone_append(struct request_queue *q,
595 						 struct bio *bio)
596 {
597 	int nr_sectors = bio_sectors(bio);
598 
599 	/* Only applicable to zoned block devices */
600 	if (!bdev_is_zoned(bio->bi_bdev))
601 		return BLK_STS_NOTSUPP;
602 
603 	/* The bio sector must point to the start of a sequential zone */
604 	if (!bdev_is_zone_start(bio->bi_bdev, bio->bi_iter.bi_sector))
605 		return BLK_STS_IOERR;
606 
607 	/*
608 	 * Not allowed to cross zone boundaries. Otherwise, the BIO will be
609 	 * split and could result in non-contiguous sectors being written in
610 	 * different zones.
611 	 */
612 	if (nr_sectors > q->limits.chunk_sectors)
613 		return BLK_STS_IOERR;
614 
615 	/* Make sure the BIO is small enough and will not get split */
616 	if (nr_sectors > q->limits.max_zone_append_sectors)
617 		return BLK_STS_IOERR;
618 
619 	bio->bi_opf |= REQ_NOMERGE;
620 
621 	return BLK_STS_OK;
622 }
623 
__submit_bio(struct bio * bio)624 static void __submit_bio(struct bio *bio)
625 {
626 	/* If plug is not used, add new plug here to cache nsecs time. */
627 	struct blk_plug plug;
628 
629 	if (unlikely(!blk_crypto_bio_prep(&bio)))
630 		return;
631 
632 	blk_start_plug(&plug);
633 
634 	if (!bdev_test_flag(bio->bi_bdev, BD_HAS_SUBMIT_BIO)) {
635 		blk_mq_submit_bio(bio);
636 	} else if (likely(bio_queue_enter(bio) == 0)) {
637 		struct gendisk *disk = bio->bi_bdev->bd_disk;
638 
639 		if ((bio->bi_opf & REQ_POLLED) &&
640 		    !(disk->queue->limits.features & BLK_FEAT_POLL)) {
641 			bio->bi_status = BLK_STS_NOTSUPP;
642 			bio_endio(bio);
643 		} else {
644 			disk->fops->submit_bio(bio);
645 		}
646 		blk_queue_exit(disk->queue);
647 	}
648 
649 	blk_finish_plug(&plug);
650 }
651 
652 /*
653  * The loop in this function may be a bit non-obvious, and so deserves some
654  * explanation:
655  *
656  *  - Before entering the loop, bio->bi_next is NULL (as all callers ensure
657  *    that), so we have a list with a single bio.
658  *  - We pretend that we have just taken it off a longer list, so we assign
659  *    bio_list to a pointer to the bio_list_on_stack, thus initialising the
660  *    bio_list of new bios to be added.  ->submit_bio() may indeed add some more
661  *    bios through a recursive call to submit_bio_noacct.  If it did, we find a
662  *    non-NULL value in bio_list and re-enter the loop from the top.
663  *  - In this case we really did just take the bio of the top of the list (no
664  *    pretending) and so remove it from bio_list, and call into ->submit_bio()
665  *    again.
666  *
667  * bio_list_on_stack[0] contains bios submitted by the current ->submit_bio.
668  * bio_list_on_stack[1] contains bios that were submitted before the current
669  *	->submit_bio, but that haven't been processed yet.
670  */
__submit_bio_noacct(struct bio * bio)671 static void __submit_bio_noacct(struct bio *bio)
672 {
673 	struct bio_list bio_list_on_stack[2];
674 
675 	BUG_ON(bio->bi_next);
676 
677 	bio_list_init(&bio_list_on_stack[0]);
678 	current->bio_list = bio_list_on_stack;
679 
680 	do {
681 		struct request_queue *q = bdev_get_queue(bio->bi_bdev);
682 		struct bio_list lower, same;
683 
684 		/*
685 		 * Create a fresh bio_list for all subordinate requests.
686 		 */
687 		bio_list_on_stack[1] = bio_list_on_stack[0];
688 		bio_list_init(&bio_list_on_stack[0]);
689 
690 		__submit_bio(bio);
691 
692 		/*
693 		 * Sort new bios into those for a lower level and those for the
694 		 * same level.
695 		 */
696 		bio_list_init(&lower);
697 		bio_list_init(&same);
698 		while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL)
699 			if (q == bdev_get_queue(bio->bi_bdev))
700 				bio_list_add(&same, bio);
701 			else
702 				bio_list_add(&lower, bio);
703 
704 		/*
705 		 * Now assemble so we handle the lowest level first.
706 		 */
707 		bio_list_merge(&bio_list_on_stack[0], &lower);
708 		bio_list_merge(&bio_list_on_stack[0], &same);
709 		bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]);
710 	} while ((bio = bio_list_pop(&bio_list_on_stack[0])));
711 
712 	current->bio_list = NULL;
713 }
714 
__submit_bio_noacct_mq(struct bio * bio)715 static void __submit_bio_noacct_mq(struct bio *bio)
716 {
717 	struct bio_list bio_list[2] = { };
718 
719 	current->bio_list = bio_list;
720 
721 	do {
722 		__submit_bio(bio);
723 	} while ((bio = bio_list_pop(&bio_list[0])));
724 
725 	current->bio_list = NULL;
726 }
727 
submit_bio_noacct_nocheck(struct bio * bio)728 void submit_bio_noacct_nocheck(struct bio *bio)
729 {
730 	blk_cgroup_bio_start(bio);
731 	blkcg_bio_issue_init(bio);
732 
733 	if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) {
734 		trace_block_bio_queue(bio);
735 		/*
736 		 * Now that enqueuing has been traced, we need to trace
737 		 * completion as well.
738 		 */
739 		bio_set_flag(bio, BIO_TRACE_COMPLETION);
740 	}
741 
742 	/*
743 	 * We only want one ->submit_bio to be active at a time, else stack
744 	 * usage with stacked devices could be a problem.  Use current->bio_list
745 	 * to collect a list of requests submited by a ->submit_bio method while
746 	 * it is active, and then process them after it returned.
747 	 */
748 	if (current->bio_list)
749 		bio_list_add(&current->bio_list[0], bio);
750 	else if (!bdev_test_flag(bio->bi_bdev, BD_HAS_SUBMIT_BIO))
751 		__submit_bio_noacct_mq(bio);
752 	else
753 		__submit_bio_noacct(bio);
754 }
755 
blk_validate_atomic_write_op_size(struct request_queue * q,struct bio * bio)756 static blk_status_t blk_validate_atomic_write_op_size(struct request_queue *q,
757 						 struct bio *bio)
758 {
759 	if (bio->bi_iter.bi_size > queue_atomic_write_unit_max_bytes(q))
760 		return BLK_STS_INVAL;
761 
762 	if (bio->bi_iter.bi_size % queue_atomic_write_unit_min_bytes(q))
763 		return BLK_STS_INVAL;
764 
765 	return BLK_STS_OK;
766 }
767 
768 /**
769  * submit_bio_noacct - re-submit a bio to the block device layer for I/O
770  * @bio:  The bio describing the location in memory and on the device.
771  *
772  * This is a version of submit_bio() that shall only be used for I/O that is
773  * resubmitted to lower level drivers by stacking block drivers.  All file
774  * systems and other upper level users of the block layer should use
775  * submit_bio() instead.
776  */
submit_bio_noacct(struct bio * bio)777 void submit_bio_noacct(struct bio *bio)
778 {
779 	struct block_device *bdev = bio->bi_bdev;
780 	struct request_queue *q = bdev_get_queue(bdev);
781 	blk_status_t status = BLK_STS_IOERR;
782 
783 	might_sleep();
784 
785 	/*
786 	 * For a REQ_NOWAIT based request, return -EOPNOTSUPP
787 	 * if queue does not support NOWAIT.
788 	 */
789 	if ((bio->bi_opf & REQ_NOWAIT) && !bdev_nowait(bdev))
790 		goto not_supported;
791 
792 	if (should_fail_bio(bio))
793 		goto end_io;
794 	bio_check_ro(bio);
795 	if (!bio_flagged(bio, BIO_REMAPPED)) {
796 		if (unlikely(bio_check_eod(bio)))
797 			goto end_io;
798 		if (bdev_is_partition(bdev) &&
799 		    unlikely(blk_partition_remap(bio)))
800 			goto end_io;
801 	}
802 
803 	/*
804 	 * Filter flush bio's early so that bio based drivers without flush
805 	 * support don't have to worry about them.
806 	 */
807 	if (op_is_flush(bio->bi_opf)) {
808 		if (WARN_ON_ONCE(bio_op(bio) != REQ_OP_WRITE &&
809 				 bio_op(bio) != REQ_OP_ZONE_APPEND))
810 			goto end_io;
811 		if (!bdev_write_cache(bdev)) {
812 			bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA);
813 			if (!bio_sectors(bio)) {
814 				status = BLK_STS_OK;
815 				goto end_io;
816 			}
817 		}
818 	}
819 
820 	switch (bio_op(bio)) {
821 	case REQ_OP_READ:
822 		break;
823 	case REQ_OP_WRITE:
824 		if (bio->bi_opf & REQ_ATOMIC) {
825 			status = blk_validate_atomic_write_op_size(q, bio);
826 			if (status != BLK_STS_OK)
827 				goto end_io;
828 		}
829 		break;
830 	case REQ_OP_FLUSH:
831 		/*
832 		 * REQ_OP_FLUSH can't be submitted through bios, it is only
833 		 * synthetized in struct request by the flush state machine.
834 		 */
835 		goto not_supported;
836 	case REQ_OP_DISCARD:
837 		if (!bdev_max_discard_sectors(bdev))
838 			goto not_supported;
839 		break;
840 	case REQ_OP_SECURE_ERASE:
841 		if (!bdev_max_secure_erase_sectors(bdev))
842 			goto not_supported;
843 		break;
844 	case REQ_OP_ZONE_APPEND:
845 		status = blk_check_zone_append(q, bio);
846 		if (status != BLK_STS_OK)
847 			goto end_io;
848 		break;
849 	case REQ_OP_WRITE_ZEROES:
850 		if (!q->limits.max_write_zeroes_sectors)
851 			goto not_supported;
852 		break;
853 	case REQ_OP_ZONE_RESET:
854 	case REQ_OP_ZONE_OPEN:
855 	case REQ_OP_ZONE_CLOSE:
856 	case REQ_OP_ZONE_FINISH:
857 	case REQ_OP_ZONE_RESET_ALL:
858 		if (!bdev_is_zoned(bio->bi_bdev))
859 			goto not_supported;
860 		break;
861 	case REQ_OP_DRV_IN:
862 	case REQ_OP_DRV_OUT:
863 		/*
864 		 * Driver private operations are only used with passthrough
865 		 * requests.
866 		 */
867 		fallthrough;
868 	default:
869 		goto not_supported;
870 	}
871 
872 	if (blk_throtl_bio(bio))
873 		return;
874 	submit_bio_noacct_nocheck(bio);
875 	return;
876 
877 not_supported:
878 	status = BLK_STS_NOTSUPP;
879 end_io:
880 	bio->bi_status = status;
881 	bio_endio(bio);
882 }
883 EXPORT_SYMBOL(submit_bio_noacct);
884 
bio_set_ioprio(struct bio * bio)885 static void bio_set_ioprio(struct bio *bio)
886 {
887 	/* Nobody set ioprio so far? Initialize it based on task's nice value */
888 	if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) == IOPRIO_CLASS_NONE)
889 		bio->bi_ioprio = get_current_ioprio();
890 	blkcg_set_ioprio(bio);
891 }
892 
893 /**
894  * submit_bio - submit a bio to the block device layer for I/O
895  * @bio: The &struct bio which describes the I/O
896  *
897  * submit_bio() is used to submit I/O requests to block devices.  It is passed a
898  * fully set up &struct bio that describes the I/O that needs to be done.  The
899  * bio will be send to the device described by the bi_bdev field.
900  *
901  * The success/failure status of the request, along with notification of
902  * completion, is delivered asynchronously through the ->bi_end_io() callback
903  * in @bio.  The bio must NOT be touched by the caller until ->bi_end_io() has
904  * been called.
905  */
submit_bio(struct bio * bio)906 void submit_bio(struct bio *bio)
907 {
908 	if (bio_op(bio) == REQ_OP_READ) {
909 		task_io_account_read(bio->bi_iter.bi_size);
910 		count_vm_events(PGPGIN, bio_sectors(bio));
911 	} else if (bio_op(bio) == REQ_OP_WRITE) {
912 		count_vm_events(PGPGOUT, bio_sectors(bio));
913 	}
914 
915 	bio_set_ioprio(bio);
916 	submit_bio_noacct(bio);
917 }
918 EXPORT_SYMBOL(submit_bio);
919 
920 /**
921  * bio_poll - poll for BIO completions
922  * @bio: bio to poll for
923  * @iob: batches of IO
924  * @flags: BLK_POLL_* flags that control the behavior
925  *
926  * Poll for completions on queue associated with the bio. Returns number of
927  * completed entries found.
928  *
929  * Note: the caller must either be the context that submitted @bio, or
930  * be in a RCU critical section to prevent freeing of @bio.
931  */
bio_poll(struct bio * bio,struct io_comp_batch * iob,unsigned int flags)932 int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags)
933 {
934 	blk_qc_t cookie = READ_ONCE(bio->bi_cookie);
935 	struct block_device *bdev;
936 	struct request_queue *q;
937 	int ret = 0;
938 
939 	bdev = READ_ONCE(bio->bi_bdev);
940 	if (!bdev)
941 		return 0;
942 
943 	q = bdev_get_queue(bdev);
944 	if (cookie == BLK_QC_T_NONE)
945 		return 0;
946 
947 	blk_flush_plug(current->plug, false);
948 
949 	/*
950 	 * We need to be able to enter a frozen queue, similar to how
951 	 * timeouts also need to do that. If that is blocked, then we can
952 	 * have pending IO when a queue freeze is started, and then the
953 	 * wait for the freeze to finish will wait for polled requests to
954 	 * timeout as the poller is preventer from entering the queue and
955 	 * completing them. As long as we prevent new IO from being queued,
956 	 * that should be all that matters.
957 	 */
958 	if (!percpu_ref_tryget(&q->q_usage_counter))
959 		return 0;
960 	if (queue_is_mq(q)) {
961 		ret = blk_mq_poll(q, cookie, iob, flags);
962 	} else {
963 		struct gendisk *disk = q->disk;
964 
965 		if ((q->limits.features & BLK_FEAT_POLL) && disk &&
966 		    disk->fops->poll_bio)
967 			ret = disk->fops->poll_bio(bio, iob, flags);
968 	}
969 	blk_queue_exit(q);
970 	return ret;
971 }
972 EXPORT_SYMBOL_GPL(bio_poll);
973 
974 /*
975  * Helper to implement file_operations.iopoll.  Requires the bio to be stored
976  * in iocb->private, and cleared before freeing the bio.
977  */
iocb_bio_iopoll(struct kiocb * kiocb,struct io_comp_batch * iob,unsigned int flags)978 int iocb_bio_iopoll(struct kiocb *kiocb, struct io_comp_batch *iob,
979 		    unsigned int flags)
980 {
981 	struct bio *bio;
982 	int ret = 0;
983 
984 	/*
985 	 * Note: the bio cache only uses SLAB_TYPESAFE_BY_RCU, so bio can
986 	 * point to a freshly allocated bio at this point.  If that happens
987 	 * we have a few cases to consider:
988 	 *
989 	 *  1) the bio is beeing initialized and bi_bdev is NULL.  We can just
990 	 *     simply nothing in this case
991 	 *  2) the bio points to a not poll enabled device.  bio_poll will catch
992 	 *     this and return 0
993 	 *  3) the bio points to a poll capable device, including but not
994 	 *     limited to the one that the original bio pointed to.  In this
995 	 *     case we will call into the actual poll method and poll for I/O,
996 	 *     even if we don't need to, but it won't cause harm either.
997 	 *
998 	 * For cases 2) and 3) above the RCU grace period ensures that bi_bdev
999 	 * is still allocated. Because partitions hold a reference to the whole
1000 	 * device bdev and thus disk, the disk is also still valid.  Grabbing
1001 	 * a reference to the queue in bio_poll() ensures the hctxs and requests
1002 	 * are still valid as well.
1003 	 */
1004 	rcu_read_lock();
1005 	bio = READ_ONCE(kiocb->private);
1006 	if (bio)
1007 		ret = bio_poll(bio, iob, flags);
1008 	rcu_read_unlock();
1009 
1010 	return ret;
1011 }
1012 EXPORT_SYMBOL_GPL(iocb_bio_iopoll);
1013 
update_io_ticks(struct block_device * part,unsigned long now,bool end)1014 void update_io_ticks(struct block_device *part, unsigned long now, bool end)
1015 {
1016 	unsigned long stamp;
1017 again:
1018 	stamp = READ_ONCE(part->bd_stamp);
1019 	if (unlikely(time_after(now, stamp)) &&
1020 	    likely(try_cmpxchg(&part->bd_stamp, &stamp, now)) &&
1021 	    (end || part_in_flight(part)))
1022 		__part_stat_add(part, io_ticks, now - stamp);
1023 
1024 	if (bdev_is_partition(part)) {
1025 		part = bdev_whole(part);
1026 		goto again;
1027 	}
1028 }
1029 
bdev_start_io_acct(struct block_device * bdev,enum req_op op,unsigned long start_time)1030 unsigned long bdev_start_io_acct(struct block_device *bdev, enum req_op op,
1031 				 unsigned long start_time)
1032 {
1033 	part_stat_lock();
1034 	update_io_ticks(bdev, start_time, false);
1035 	part_stat_local_inc(bdev, in_flight[op_is_write(op)]);
1036 	part_stat_unlock();
1037 
1038 	return start_time;
1039 }
1040 EXPORT_SYMBOL(bdev_start_io_acct);
1041 
1042 /**
1043  * bio_start_io_acct - start I/O accounting for bio based drivers
1044  * @bio:	bio to start account for
1045  *
1046  * Returns the start time that should be passed back to bio_end_io_acct().
1047  */
bio_start_io_acct(struct bio * bio)1048 unsigned long bio_start_io_acct(struct bio *bio)
1049 {
1050 	return bdev_start_io_acct(bio->bi_bdev, bio_op(bio), jiffies);
1051 }
1052 EXPORT_SYMBOL_GPL(bio_start_io_acct);
1053 
bdev_end_io_acct(struct block_device * bdev,enum req_op op,unsigned int sectors,unsigned long start_time)1054 void bdev_end_io_acct(struct block_device *bdev, enum req_op op,
1055 		      unsigned int sectors, unsigned long start_time)
1056 {
1057 	const int sgrp = op_stat_group(op);
1058 	unsigned long now = READ_ONCE(jiffies);
1059 	unsigned long duration = now - start_time;
1060 
1061 	part_stat_lock();
1062 	update_io_ticks(bdev, now, true);
1063 	part_stat_inc(bdev, ios[sgrp]);
1064 	part_stat_add(bdev, sectors[sgrp], sectors);
1065 	part_stat_add(bdev, nsecs[sgrp], jiffies_to_nsecs(duration));
1066 	part_stat_local_dec(bdev, in_flight[op_is_write(op)]);
1067 	part_stat_unlock();
1068 }
1069 EXPORT_SYMBOL(bdev_end_io_acct);
1070 
bio_end_io_acct_remapped(struct bio * bio,unsigned long start_time,struct block_device * orig_bdev)1071 void bio_end_io_acct_remapped(struct bio *bio, unsigned long start_time,
1072 			      struct block_device *orig_bdev)
1073 {
1074 	bdev_end_io_acct(orig_bdev, bio_op(bio), bio_sectors(bio), start_time);
1075 }
1076 EXPORT_SYMBOL_GPL(bio_end_io_acct_remapped);
1077 
1078 /**
1079  * blk_lld_busy - Check if underlying low-level drivers of a device are busy
1080  * @q : the queue of the device being checked
1081  *
1082  * Description:
1083  *    Check if underlying low-level drivers of a device are busy.
1084  *    If the drivers want to export their busy state, they must set own
1085  *    exporting function using blk_queue_lld_busy() first.
1086  *
1087  *    Basically, this function is used only by request stacking drivers
1088  *    to stop dispatching requests to underlying devices when underlying
1089  *    devices are busy.  This behavior helps more I/O merging on the queue
1090  *    of the request stacking driver and prevents I/O throughput regression
1091  *    on burst I/O load.
1092  *
1093  * Return:
1094  *    0 - Not busy (The request stacking driver should dispatch request)
1095  *    1 - Busy (The request stacking driver should stop dispatching request)
1096  */
blk_lld_busy(struct request_queue * q)1097 int blk_lld_busy(struct request_queue *q)
1098 {
1099 	if (queue_is_mq(q) && q->mq_ops->busy)
1100 		return q->mq_ops->busy(q);
1101 
1102 	return 0;
1103 }
1104 EXPORT_SYMBOL_GPL(blk_lld_busy);
1105 
kblockd_schedule_work(struct work_struct * work)1106 int kblockd_schedule_work(struct work_struct *work)
1107 {
1108 	return queue_work(kblockd_workqueue, work);
1109 }
1110 EXPORT_SYMBOL(kblockd_schedule_work);
1111 
kblockd_mod_delayed_work_on(int cpu,struct delayed_work * dwork,unsigned long delay)1112 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork,
1113 				unsigned long delay)
1114 {
1115 	return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
1116 }
1117 EXPORT_SYMBOL(kblockd_mod_delayed_work_on);
1118 
blk_start_plug_nr_ios(struct blk_plug * plug,unsigned short nr_ios)1119 void blk_start_plug_nr_ios(struct blk_plug *plug, unsigned short nr_ios)
1120 {
1121 	struct task_struct *tsk = current;
1122 
1123 	/*
1124 	 * If this is a nested plug, don't actually assign it.
1125 	 */
1126 	if (tsk->plug)
1127 		return;
1128 
1129 	plug->cur_ktime = 0;
1130 	rq_list_init(&plug->mq_list);
1131 	rq_list_init(&plug->cached_rqs);
1132 	plug->nr_ios = min_t(unsigned short, nr_ios, BLK_MAX_REQUEST_COUNT);
1133 	plug->rq_count = 0;
1134 	plug->multiple_queues = false;
1135 	plug->has_elevator = false;
1136 	INIT_LIST_HEAD(&plug->cb_list);
1137 
1138 	/*
1139 	 * Store ordering should not be needed here, since a potential
1140 	 * preempt will imply a full memory barrier
1141 	 */
1142 	tsk->plug = plug;
1143 }
1144 
1145 /**
1146  * blk_start_plug - initialize blk_plug and track it inside the task_struct
1147  * @plug:	The &struct blk_plug that needs to be initialized
1148  *
1149  * Description:
1150  *   blk_start_plug() indicates to the block layer an intent by the caller
1151  *   to submit multiple I/O requests in a batch.  The block layer may use
1152  *   this hint to defer submitting I/Os from the caller until blk_finish_plug()
1153  *   is called.  However, the block layer may choose to submit requests
1154  *   before a call to blk_finish_plug() if the number of queued I/Os
1155  *   exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than
1156  *   %BLK_PLUG_FLUSH_SIZE.  The queued I/Os may also be submitted early if
1157  *   the task schedules (see below).
1158  *
1159  *   Tracking blk_plug inside the task_struct will help with auto-flushing the
1160  *   pending I/O should the task end up blocking between blk_start_plug() and
1161  *   blk_finish_plug(). This is important from a performance perspective, but
1162  *   also ensures that we don't deadlock. For instance, if the task is blocking
1163  *   for a memory allocation, memory reclaim could end up wanting to free a
1164  *   page belonging to that request that is currently residing in our private
1165  *   plug. By flushing the pending I/O when the process goes to sleep, we avoid
1166  *   this kind of deadlock.
1167  */
blk_start_plug(struct blk_plug * plug)1168 void blk_start_plug(struct blk_plug *plug)
1169 {
1170 	blk_start_plug_nr_ios(plug, 1);
1171 }
1172 EXPORT_SYMBOL(blk_start_plug);
1173 
flush_plug_callbacks(struct blk_plug * plug,bool from_schedule)1174 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
1175 {
1176 	LIST_HEAD(callbacks);
1177 
1178 	while (!list_empty(&plug->cb_list)) {
1179 		list_splice_init(&plug->cb_list, &callbacks);
1180 
1181 		while (!list_empty(&callbacks)) {
1182 			struct blk_plug_cb *cb = list_first_entry(&callbacks,
1183 							  struct blk_plug_cb,
1184 							  list);
1185 			list_del(&cb->list);
1186 			cb->callback(cb, from_schedule);
1187 		}
1188 	}
1189 }
1190 
blk_check_plugged(blk_plug_cb_fn unplug,void * data,int size)1191 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
1192 				      int size)
1193 {
1194 	struct blk_plug *plug = current->plug;
1195 	struct blk_plug_cb *cb;
1196 
1197 	if (!plug)
1198 		return NULL;
1199 
1200 	list_for_each_entry(cb, &plug->cb_list, list)
1201 		if (cb->callback == unplug && cb->data == data)
1202 			return cb;
1203 
1204 	/* Not currently on the callback list */
1205 	BUG_ON(size < sizeof(*cb));
1206 	cb = kzalloc(size, GFP_ATOMIC);
1207 	if (cb) {
1208 		cb->data = data;
1209 		cb->callback = unplug;
1210 		list_add(&cb->list, &plug->cb_list);
1211 	}
1212 	return cb;
1213 }
1214 EXPORT_SYMBOL(blk_check_plugged);
1215 
__blk_flush_plug(struct blk_plug * plug,bool from_schedule)1216 void __blk_flush_plug(struct blk_plug *plug, bool from_schedule)
1217 {
1218 	if (!list_empty(&plug->cb_list))
1219 		flush_plug_callbacks(plug, from_schedule);
1220 	blk_mq_flush_plug_list(plug, from_schedule);
1221 	/*
1222 	 * Unconditionally flush out cached requests, even if the unplug
1223 	 * event came from schedule. Since we know hold references to the
1224 	 * queue for cached requests, we don't want a blocked task holding
1225 	 * up a queue freeze/quiesce event.
1226 	 */
1227 	if (unlikely(!rq_list_empty(&plug->cached_rqs)))
1228 		blk_mq_free_plug_rqs(plug);
1229 
1230 	plug->cur_ktime = 0;
1231 	current->flags &= ~PF_BLOCK_TS;
1232 }
1233 
1234 /**
1235  * blk_finish_plug - mark the end of a batch of submitted I/O
1236  * @plug:	The &struct blk_plug passed to blk_start_plug()
1237  *
1238  * Description:
1239  * Indicate that a batch of I/O submissions is complete.  This function
1240  * must be paired with an initial call to blk_start_plug().  The intent
1241  * is to allow the block layer to optimize I/O submission.  See the
1242  * documentation for blk_start_plug() for more information.
1243  */
blk_finish_plug(struct blk_plug * plug)1244 void blk_finish_plug(struct blk_plug *plug)
1245 {
1246 	if (plug == current->plug) {
1247 		__blk_flush_plug(plug, false);
1248 		current->plug = NULL;
1249 	}
1250 }
1251 EXPORT_SYMBOL(blk_finish_plug);
1252 
blk_io_schedule(void)1253 void blk_io_schedule(void)
1254 {
1255 	/* Prevent hang_check timer from firing at us during very long I/O */
1256 	unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2;
1257 
1258 	if (timeout)
1259 		io_schedule_timeout(timeout);
1260 	else
1261 		io_schedule();
1262 }
1263 EXPORT_SYMBOL_GPL(blk_io_schedule);
1264 
blk_dev_init(void)1265 int __init blk_dev_init(void)
1266 {
1267 	BUILD_BUG_ON((__force u32)REQ_OP_LAST >= (1 << REQ_OP_BITS));
1268 	BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
1269 			sizeof_field(struct request, cmd_flags));
1270 	BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
1271 			sizeof_field(struct bio, bi_opf));
1272 
1273 	/* used for unplugging and affects IO latency/throughput - HIGHPRI */
1274 	kblockd_workqueue = alloc_workqueue("kblockd",
1275 					    WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1276 	if (!kblockd_workqueue)
1277 		panic("Failed to create kblockd\n");
1278 
1279 	blk_requestq_cachep = KMEM_CACHE(request_queue, SLAB_PANIC);
1280 
1281 	blk_debugfs_root = debugfs_create_dir("block", NULL);
1282 
1283 	return 0;
1284 }
1285