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