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