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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/backing-dev.h> | |
18 | #include <linux/bio.h> | |
19 | #include <linux/blkdev.h> | |
20 | #include <linux/blk-mq.h> | |
21 | #include <linux/highmem.h> | |
22 | #include <linux/mm.h> | |
23 | #include <linux/kernel_stat.h> | |
24 | #include <linux/string.h> | |
25 | #include <linux/init.h> | |
26 | #include <linux/completion.h> | |
27 | #include <linux/slab.h> | |
28 | #include <linux/swap.h> | |
29 | #include <linux/writeback.h> | |
30 | #include <linux/task_io_accounting_ops.h> | |
31 | #include <linux/fault-inject.h> | |
32 | #include <linux/list_sort.h> | |
33 | #include <linux/delay.h> | |
34 | #include <linux/ratelimit.h> | |
35 | #include <linux/pm_runtime.h> | |
36 | #include <linux/blk-cgroup.h> | |
37 | #include <linux/debugfs.h> | |
38 | #include <linux/bpf.h> | |
39 | ||
40 | #define CREATE_TRACE_POINTS | |
41 | #include <trace/events/block.h> | |
42 | ||
43 | #include "blk.h" | |
44 | #include "blk-mq.h" | |
45 | #include "blk-mq-sched.h" | |
46 | #include "blk-pm.h" | |
47 | #include "blk-rq-qos.h" | |
48 | ||
49 | #ifdef CONFIG_DEBUG_FS | |
50 | struct dentry *blk_debugfs_root; | |
51 | #endif | |
52 | ||
53 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); | |
54 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); | |
55 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); | |
56 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_split); | |
57 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug); | |
58 | ||
59 | DEFINE_IDA(blk_queue_ida); | |
60 | ||
61 | /* | |
62 | * For queue allocation | |
63 | */ | |
64 | struct kmem_cache *blk_requestq_cachep; | |
65 | ||
66 | /* | |
67 | * Controlling structure to kblockd | |
68 | */ | |
69 | static struct workqueue_struct *kblockd_workqueue; | |
70 | ||
71 | /** | |
72 | * blk_queue_flag_set - atomically set a queue flag | |
73 | * @flag: flag to be set | |
74 | * @q: request queue | |
75 | */ | |
76 | void blk_queue_flag_set(unsigned int flag, struct request_queue *q) | |
77 | { | |
78 | set_bit(flag, &q->queue_flags); | |
79 | } | |
80 | EXPORT_SYMBOL(blk_queue_flag_set); | |
81 | ||
82 | /** | |
83 | * blk_queue_flag_clear - atomically clear a queue flag | |
84 | * @flag: flag to be cleared | |
85 | * @q: request queue | |
86 | */ | |
87 | void blk_queue_flag_clear(unsigned int flag, struct request_queue *q) | |
88 | { | |
89 | clear_bit(flag, &q->queue_flags); | |
90 | } | |
91 | EXPORT_SYMBOL(blk_queue_flag_clear); | |
92 | ||
93 | /** | |
94 | * blk_queue_flag_test_and_set - atomically test and set a queue flag | |
95 | * @flag: flag to be set | |
96 | * @q: request queue | |
97 | * | |
98 | * Returns the previous value of @flag - 0 if the flag was not set and 1 if | |
99 | * the flag was already set. | |
100 | */ | |
101 | bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q) | |
102 | { | |
103 | return test_and_set_bit(flag, &q->queue_flags); | |
104 | } | |
105 | EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set); | |
106 | ||
107 | void blk_rq_init(struct request_queue *q, struct request *rq) | |
108 | { | |
109 | memset(rq, 0, sizeof(*rq)); | |
110 | ||
111 | INIT_LIST_HEAD(&rq->queuelist); | |
112 | rq->q = q; | |
113 | rq->__sector = (sector_t) -1; | |
114 | INIT_HLIST_NODE(&rq->hash); | |
115 | RB_CLEAR_NODE(&rq->rb_node); | |
116 | rq->tag = -1; | |
117 | rq->internal_tag = -1; | |
118 | rq->start_time_ns = ktime_get_ns(); | |
119 | rq->part = NULL; | |
120 | } | |
121 | EXPORT_SYMBOL(blk_rq_init); | |
122 | ||
123 | static const struct { | |
124 | int errno; | |
125 | const char *name; | |
126 | } blk_errors[] = { | |
127 | [BLK_STS_OK] = { 0, "" }, | |
128 | [BLK_STS_NOTSUPP] = { -EOPNOTSUPP, "operation not supported" }, | |
129 | [BLK_STS_TIMEOUT] = { -ETIMEDOUT, "timeout" }, | |
130 | [BLK_STS_NOSPC] = { -ENOSPC, "critical space allocation" }, | |
131 | [BLK_STS_TRANSPORT] = { -ENOLINK, "recoverable transport" }, | |
132 | [BLK_STS_TARGET] = { -EREMOTEIO, "critical target" }, | |
133 | [BLK_STS_NEXUS] = { -EBADE, "critical nexus" }, | |
134 | [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" }, | |
135 | [BLK_STS_PROTECTION] = { -EILSEQ, "protection" }, | |
136 | [BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" }, | |
137 | [BLK_STS_DEV_RESOURCE] = { -EBUSY, "device resource" }, | |
138 | [BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" }, | |
139 | ||
140 | /* device mapper special case, should not leak out: */ | |
141 | [BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" }, | |
142 | ||
143 | /* everything else not covered above: */ | |
144 | [BLK_STS_IOERR] = { -EIO, "I/O" }, | |
145 | }; | |
146 | ||
147 | blk_status_t errno_to_blk_status(int errno) | |
148 | { | |
149 | int i; | |
150 | ||
151 | for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { | |
152 | if (blk_errors[i].errno == errno) | |
153 | return (__force blk_status_t)i; | |
154 | } | |
155 | ||
156 | return BLK_STS_IOERR; | |
157 | } | |
158 | EXPORT_SYMBOL_GPL(errno_to_blk_status); | |
159 | ||
160 | int blk_status_to_errno(blk_status_t status) | |
161 | { | |
162 | int idx = (__force int)status; | |
163 | ||
164 | if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) | |
165 | return -EIO; | |
166 | return blk_errors[idx].errno; | |
167 | } | |
168 | EXPORT_SYMBOL_GPL(blk_status_to_errno); | |
169 | ||
170 | static void print_req_error(struct request *req, blk_status_t status) | |
171 | { | |
172 | int idx = (__force int)status; | |
173 | ||
174 | if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) | |
175 | return; | |
176 | ||
177 | printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu flags %x\n", | |
178 | __func__, blk_errors[idx].name, | |
179 | req->rq_disk ? req->rq_disk->disk_name : "?", | |
180 | (unsigned long long)blk_rq_pos(req), | |
181 | req->cmd_flags); | |
182 | } | |
183 | ||
184 | static void req_bio_endio(struct request *rq, struct bio *bio, | |
185 | unsigned int nbytes, blk_status_t error) | |
186 | { | |
187 | if (error) | |
188 | bio->bi_status = error; | |
189 | ||
190 | if (unlikely(rq->rq_flags & RQF_QUIET)) | |
191 | bio_set_flag(bio, BIO_QUIET); | |
192 | ||
193 | bio_advance(bio, nbytes); | |
194 | ||
195 | /* don't actually finish bio if it's part of flush sequence */ | |
196 | if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ)) | |
197 | bio_endio(bio); | |
198 | } | |
199 | ||
200 | void blk_dump_rq_flags(struct request *rq, char *msg) | |
201 | { | |
202 | printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg, | |
203 | rq->rq_disk ? rq->rq_disk->disk_name : "?", | |
204 | (unsigned long long) rq->cmd_flags); | |
205 | ||
206 | printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", | |
207 | (unsigned long long)blk_rq_pos(rq), | |
208 | blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); | |
209 | printk(KERN_INFO " bio %p, biotail %p, len %u\n", | |
210 | rq->bio, rq->biotail, blk_rq_bytes(rq)); | |
211 | } | |
212 | EXPORT_SYMBOL(blk_dump_rq_flags); | |
213 | ||
214 | /** | |
215 | * blk_sync_queue - cancel any pending callbacks on a queue | |
216 | * @q: the queue | |
217 | * | |
218 | * Description: | |
219 | * The block layer may perform asynchronous callback activity | |
220 | * on a queue, such as calling the unplug function after a timeout. | |
221 | * A block device may call blk_sync_queue to ensure that any | |
222 | * such activity is cancelled, thus allowing it to release resources | |
223 | * that the callbacks might use. The caller must already have made sure | |
224 | * that its ->make_request_fn will not re-add plugging prior to calling | |
225 | * this function. | |
226 | * | |
227 | * This function does not cancel any asynchronous activity arising | |
228 | * out of elevator or throttling code. That would require elevator_exit() | |
229 | * and blkcg_exit_queue() to be called with queue lock initialized. | |
230 | * | |
231 | */ | |
232 | void blk_sync_queue(struct request_queue *q) | |
233 | { | |
234 | del_timer_sync(&q->timeout); | |
235 | cancel_work_sync(&q->timeout_work); | |
236 | } | |
237 | EXPORT_SYMBOL(blk_sync_queue); | |
238 | ||
239 | /** | |
240 | * blk_set_pm_only - increment pm_only counter | |
241 | * @q: request queue pointer | |
242 | */ | |
243 | void blk_set_pm_only(struct request_queue *q) | |
244 | { | |
245 | atomic_inc(&q->pm_only); | |
246 | } | |
247 | EXPORT_SYMBOL_GPL(blk_set_pm_only); | |
248 | ||
249 | void blk_clear_pm_only(struct request_queue *q) | |
250 | { | |
251 | int pm_only; | |
252 | ||
253 | pm_only = atomic_dec_return(&q->pm_only); | |
254 | WARN_ON_ONCE(pm_only < 0); | |
255 | if (pm_only == 0) | |
256 | wake_up_all(&q->mq_freeze_wq); | |
257 | } | |
258 | EXPORT_SYMBOL_GPL(blk_clear_pm_only); | |
259 | ||
260 | void blk_put_queue(struct request_queue *q) | |
261 | { | |
262 | kobject_put(&q->kobj); | |
263 | } | |
264 | EXPORT_SYMBOL(blk_put_queue); | |
265 | ||
266 | void blk_set_queue_dying(struct request_queue *q) | |
267 | { | |
268 | blk_queue_flag_set(QUEUE_FLAG_DYING, q); | |
269 | ||
270 | /* | |
271 | * When queue DYING flag is set, we need to block new req | |
272 | * entering queue, so we call blk_freeze_queue_start() to | |
273 | * prevent I/O from crossing blk_queue_enter(). | |
274 | */ | |
275 | blk_freeze_queue_start(q); | |
276 | ||
277 | if (queue_is_mq(q)) | |
278 | blk_mq_wake_waiters(q); | |
279 | ||
280 | /* Make blk_queue_enter() reexamine the DYING flag. */ | |
281 | wake_up_all(&q->mq_freeze_wq); | |
282 | } | |
283 | EXPORT_SYMBOL_GPL(blk_set_queue_dying); | |
284 | ||
285 | /** | |
286 | * blk_cleanup_queue - shutdown a request queue | |
287 | * @q: request queue to shutdown | |
288 | * | |
289 | * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and | |
290 | * put it. All future requests will be failed immediately with -ENODEV. | |
291 | */ | |
292 | void blk_cleanup_queue(struct request_queue *q) | |
293 | { | |
294 | /* mark @q DYING, no new request or merges will be allowed afterwards */ | |
295 | mutex_lock(&q->sysfs_lock); | |
296 | blk_set_queue_dying(q); | |
297 | ||
298 | blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q); | |
299 | blk_queue_flag_set(QUEUE_FLAG_NOXMERGES, q); | |
300 | blk_queue_flag_set(QUEUE_FLAG_DYING, q); | |
301 | mutex_unlock(&q->sysfs_lock); | |
302 | ||
303 | /* | |
304 | * Drain all requests queued before DYING marking. Set DEAD flag to | |
305 | * prevent that q->request_fn() gets invoked after draining finished. | |
306 | */ | |
307 | blk_freeze_queue(q); | |
308 | ||
309 | rq_qos_exit(q); | |
310 | ||
311 | blk_queue_flag_set(QUEUE_FLAG_DEAD, q); | |
312 | ||
313 | /* for synchronous bio-based driver finish in-flight integrity i/o */ | |
314 | blk_flush_integrity(); | |
315 | ||
316 | /* @q won't process any more request, flush async actions */ | |
317 | del_timer_sync(&q->backing_dev_info->laptop_mode_wb_timer); | |
318 | blk_sync_queue(q); | |
319 | ||
320 | if (queue_is_mq(q)) | |
321 | blk_mq_exit_queue(q); | |
322 | ||
323 | percpu_ref_exit(&q->q_usage_counter); | |
324 | ||
325 | /* @q is and will stay empty, shutdown and put */ | |
326 | blk_put_queue(q); | |
327 | } | |
328 | EXPORT_SYMBOL(blk_cleanup_queue); | |
329 | ||
330 | struct request_queue *blk_alloc_queue(gfp_t gfp_mask) | |
331 | { | |
332 | return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE); | |
333 | } | |
334 | EXPORT_SYMBOL(blk_alloc_queue); | |
335 | ||
336 | /** | |
337 | * blk_queue_enter() - try to increase q->q_usage_counter | |
338 | * @q: request queue pointer | |
339 | * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT | |
340 | */ | |
341 | int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) | |
342 | { | |
343 | const bool pm = flags & BLK_MQ_REQ_PREEMPT; | |
344 | ||
345 | while (true) { | |
346 | bool success = false; | |
347 | ||
348 | rcu_read_lock(); | |
349 | if (percpu_ref_tryget_live(&q->q_usage_counter)) { | |
350 | /* | |
351 | * The code that increments the pm_only counter is | |
352 | * responsible for ensuring that that counter is | |
353 | * globally visible before the queue is unfrozen. | |
354 | */ | |
355 | if (pm || !blk_queue_pm_only(q)) { | |
356 | success = true; | |
357 | } else { | |
358 | percpu_ref_put(&q->q_usage_counter); | |
359 | } | |
360 | } | |
361 | rcu_read_unlock(); | |
362 | ||
363 | if (success) | |
364 | return 0; | |
365 | ||
366 | if (flags & BLK_MQ_REQ_NOWAIT) | |
367 | return -EBUSY; | |
368 | ||
369 | /* | |
370 | * read pair of barrier in blk_freeze_queue_start(), | |
371 | * we need to order reading __PERCPU_REF_DEAD flag of | |
372 | * .q_usage_counter and reading .mq_freeze_depth or | |
373 | * queue dying flag, otherwise the following wait may | |
374 | * never return if the two reads are reordered. | |
375 | */ | |
376 | smp_rmb(); | |
377 | ||
378 | wait_event(q->mq_freeze_wq, | |
379 | (!q->mq_freeze_depth && | |
380 | (pm || (blk_pm_request_resume(q), | |
381 | !blk_queue_pm_only(q)))) || | |
382 | blk_queue_dying(q)); | |
383 | if (blk_queue_dying(q)) | |
384 | return -ENODEV; | |
385 | } | |
386 | } | |
387 | ||
388 | void blk_queue_exit(struct request_queue *q) | |
389 | { | |
390 | percpu_ref_put(&q->q_usage_counter); | |
391 | } | |
392 | ||
393 | static void blk_queue_usage_counter_release(struct percpu_ref *ref) | |
394 | { | |
395 | struct request_queue *q = | |
396 | container_of(ref, struct request_queue, q_usage_counter); | |
397 | ||
398 | wake_up_all(&q->mq_freeze_wq); | |
399 | } | |
400 | ||
401 | static void blk_rq_timed_out_timer(struct timer_list *t) | |
402 | { | |
403 | struct request_queue *q = from_timer(q, t, timeout); | |
404 | ||
405 | kblockd_schedule_work(&q->timeout_work); | |
406 | } | |
407 | ||
408 | static void blk_timeout_work(struct work_struct *work) | |
409 | { | |
410 | } | |
411 | ||
412 | /** | |
413 | * blk_alloc_queue_node - allocate a request queue | |
414 | * @gfp_mask: memory allocation flags | |
415 | * @node_id: NUMA node to allocate memory from | |
416 | */ | |
417 | struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) | |
418 | { | |
419 | struct request_queue *q; | |
420 | int ret; | |
421 | ||
422 | q = kmem_cache_alloc_node(blk_requestq_cachep, | |
423 | gfp_mask | __GFP_ZERO, node_id); | |
424 | if (!q) | |
425 | return NULL; | |
426 | ||
427 | INIT_LIST_HEAD(&q->queue_head); | |
428 | q->last_merge = NULL; | |
429 | ||
430 | q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask); | |
431 | if (q->id < 0) | |
432 | goto fail_q; | |
433 | ||
434 | ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS); | |
435 | if (ret) | |
436 | goto fail_id; | |
437 | ||
438 | q->backing_dev_info = bdi_alloc_node(gfp_mask, node_id); | |
439 | if (!q->backing_dev_info) | |
440 | goto fail_split; | |
441 | ||
442 | q->stats = blk_alloc_queue_stats(); | |
443 | if (!q->stats) | |
444 | goto fail_stats; | |
445 | ||
446 | q->backing_dev_info->ra_pages = VM_READAHEAD_PAGES; | |
447 | q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK; | |
448 | q->backing_dev_info->name = "block"; | |
449 | q->node = node_id; | |
450 | ||
451 | timer_setup(&q->backing_dev_info->laptop_mode_wb_timer, | |
452 | laptop_mode_timer_fn, 0); | |
453 | timer_setup(&q->timeout, blk_rq_timed_out_timer, 0); | |
454 | INIT_WORK(&q->timeout_work, blk_timeout_work); | |
455 | INIT_LIST_HEAD(&q->icq_list); | |
456 | #ifdef CONFIG_BLK_CGROUP | |
457 | INIT_LIST_HEAD(&q->blkg_list); | |
458 | #endif | |
459 | ||
460 | kobject_init(&q->kobj, &blk_queue_ktype); | |
461 | ||
462 | #ifdef CONFIG_BLK_DEV_IO_TRACE | |
463 | mutex_init(&q->blk_trace_mutex); | |
464 | #endif | |
465 | mutex_init(&q->sysfs_lock); | |
466 | spin_lock_init(&q->queue_lock); | |
467 | ||
468 | init_waitqueue_head(&q->mq_freeze_wq); | |
469 | mutex_init(&q->mq_freeze_lock); | |
470 | ||
471 | /* | |
472 | * Init percpu_ref in atomic mode so that it's faster to shutdown. | |
473 | * See blk_register_queue() for details. | |
474 | */ | |
475 | if (percpu_ref_init(&q->q_usage_counter, | |
476 | blk_queue_usage_counter_release, | |
477 | PERCPU_REF_INIT_ATOMIC, GFP_KERNEL)) | |
478 | goto fail_bdi; | |
479 | ||
480 | if (blkcg_init_queue(q)) | |
481 | goto fail_ref; | |
482 | ||
483 | return q; | |
484 | ||
485 | fail_ref: | |
486 | percpu_ref_exit(&q->q_usage_counter); | |
487 | fail_bdi: | |
488 | blk_free_queue_stats(q->stats); | |
489 | fail_stats: | |
490 | bdi_put(q->backing_dev_info); | |
491 | fail_split: | |
492 | bioset_exit(&q->bio_split); | |
493 | fail_id: | |
494 | ida_simple_remove(&blk_queue_ida, q->id); | |
495 | fail_q: | |
496 | kmem_cache_free(blk_requestq_cachep, q); | |
497 | return NULL; | |
498 | } | |
499 | EXPORT_SYMBOL(blk_alloc_queue_node); | |
500 | ||
501 | bool blk_get_queue(struct request_queue *q) | |
502 | { | |
503 | if (likely(!blk_queue_dying(q))) { | |
504 | __blk_get_queue(q); | |
505 | return true; | |
506 | } | |
507 | ||
508 | return false; | |
509 | } | |
510 | EXPORT_SYMBOL(blk_get_queue); | |
511 | ||
512 | /** | |
513 | * blk_get_request - allocate a request | |
514 | * @q: request queue to allocate a request for | |
515 | * @op: operation (REQ_OP_*) and REQ_* flags, e.g. REQ_SYNC. | |
516 | * @flags: BLK_MQ_REQ_* flags, e.g. BLK_MQ_REQ_NOWAIT. | |
517 | */ | |
518 | struct request *blk_get_request(struct request_queue *q, unsigned int op, | |
519 | blk_mq_req_flags_t flags) | |
520 | { | |
521 | struct request *req; | |
522 | ||
523 | WARN_ON_ONCE(op & REQ_NOWAIT); | |
524 | WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT)); | |
525 | ||
526 | req = blk_mq_alloc_request(q, op, flags); | |
527 | if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn) | |
528 | q->mq_ops->initialize_rq_fn(req); | |
529 | ||
530 | return req; | |
531 | } | |
532 | EXPORT_SYMBOL(blk_get_request); | |
533 | ||
534 | void blk_put_request(struct request *req) | |
535 | { | |
536 | blk_mq_free_request(req); | |
537 | } | |
538 | EXPORT_SYMBOL(blk_put_request); | |
539 | ||
540 | bool bio_attempt_back_merge(struct request_queue *q, struct request *req, | |
541 | struct bio *bio) | |
542 | { | |
543 | const int ff = bio->bi_opf & REQ_FAILFAST_MASK; | |
544 | ||
545 | if (!ll_back_merge_fn(q, req, bio)) | |
546 | return false; | |
547 | ||
548 | trace_block_bio_backmerge(q, req, bio); | |
549 | ||
550 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) | |
551 | blk_rq_set_mixed_merge(req); | |
552 | ||
553 | req->biotail->bi_next = bio; | |
554 | req->biotail = bio; | |
555 | req->__data_len += bio->bi_iter.bi_size; | |
556 | ||
557 | blk_account_io_start(req, false); | |
558 | return true; | |
559 | } | |
560 | ||
561 | bool bio_attempt_front_merge(struct request_queue *q, struct request *req, | |
562 | struct bio *bio) | |
563 | { | |
564 | const int ff = bio->bi_opf & REQ_FAILFAST_MASK; | |
565 | ||
566 | if (!ll_front_merge_fn(q, req, bio)) | |
567 | return false; | |
568 | ||
569 | trace_block_bio_frontmerge(q, req, bio); | |
570 | ||
571 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) | |
572 | blk_rq_set_mixed_merge(req); | |
573 | ||
574 | bio->bi_next = req->bio; | |
575 | req->bio = bio; | |
576 | ||
577 | req->__sector = bio->bi_iter.bi_sector; | |
578 | req->__data_len += bio->bi_iter.bi_size; | |
579 | ||
580 | blk_account_io_start(req, false); | |
581 | return true; | |
582 | } | |
583 | ||
584 | bool bio_attempt_discard_merge(struct request_queue *q, struct request *req, | |
585 | struct bio *bio) | |
586 | { | |
587 | unsigned short segments = blk_rq_nr_discard_segments(req); | |
588 | ||
589 | if (segments >= queue_max_discard_segments(q)) | |
590 | goto no_merge; | |
591 | if (blk_rq_sectors(req) + bio_sectors(bio) > | |
592 | blk_rq_get_max_sectors(req, blk_rq_pos(req))) | |
593 | goto no_merge; | |
594 | ||
595 | req->biotail->bi_next = bio; | |
596 | req->biotail = bio; | |
597 | req->__data_len += bio->bi_iter.bi_size; | |
598 | req->nr_phys_segments = segments + 1; | |
599 | ||
600 | blk_account_io_start(req, false); | |
601 | return true; | |
602 | no_merge: | |
603 | req_set_nomerge(q, req); | |
604 | return false; | |
605 | } | |
606 | ||
607 | /** | |
608 | * blk_attempt_plug_merge - try to merge with %current's plugged list | |
609 | * @q: request_queue new bio is being queued at | |
610 | * @bio: new bio being queued | |
611 | * @same_queue_rq: pointer to &struct request that gets filled in when | |
612 | * another request associated with @q is found on the plug list | |
613 | * (optional, may be %NULL) | |
614 | * | |
615 | * Determine whether @bio being queued on @q can be merged with a request | |
616 | * on %current's plugged list. Returns %true if merge was successful, | |
617 | * otherwise %false. | |
618 | * | |
619 | * Plugging coalesces IOs from the same issuer for the same purpose without | |
620 | * going through @q->queue_lock. As such it's more of an issuing mechanism | |
621 | * than scheduling, and the request, while may have elvpriv data, is not | |
622 | * added on the elevator at this point. In addition, we don't have | |
623 | * reliable access to the elevator outside queue lock. Only check basic | |
624 | * merging parameters without querying the elevator. | |
625 | * | |
626 | * Caller must ensure !blk_queue_nomerges(q) beforehand. | |
627 | */ | |
628 | bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, | |
629 | struct request **same_queue_rq) | |
630 | { | |
631 | struct blk_plug *plug; | |
632 | struct request *rq; | |
633 | struct list_head *plug_list; | |
634 | ||
635 | plug = current->plug; | |
636 | if (!plug) | |
637 | return false; | |
638 | ||
639 | plug_list = &plug->mq_list; | |
640 | ||
641 | list_for_each_entry_reverse(rq, plug_list, queuelist) { | |
642 | bool merged = false; | |
643 | ||
644 | if (rq->q == q && same_queue_rq) { | |
645 | /* | |
646 | * Only blk-mq multiple hardware queues case checks the | |
647 | * rq in the same queue, there should be only one such | |
648 | * rq in a queue | |
649 | **/ | |
650 | *same_queue_rq = rq; | |
651 | } | |
652 | ||
653 | if (rq->q != q || !blk_rq_merge_ok(rq, bio)) | |
654 | continue; | |
655 | ||
656 | switch (blk_try_merge(rq, bio)) { | |
657 | case ELEVATOR_BACK_MERGE: | |
658 | merged = bio_attempt_back_merge(q, rq, bio); | |
659 | break; | |
660 | case ELEVATOR_FRONT_MERGE: | |
661 | merged = bio_attempt_front_merge(q, rq, bio); | |
662 | break; | |
663 | case ELEVATOR_DISCARD_MERGE: | |
664 | merged = bio_attempt_discard_merge(q, rq, bio); | |
665 | break; | |
666 | default: | |
667 | break; | |
668 | } | |
669 | ||
670 | if (merged) | |
671 | return true; | |
672 | } | |
673 | ||
674 | return false; | |
675 | } | |
676 | ||
677 | void blk_init_request_from_bio(struct request *req, struct bio *bio) | |
678 | { | |
679 | if (bio->bi_opf & REQ_RAHEAD) | |
680 | req->cmd_flags |= REQ_FAILFAST_MASK; | |
681 | ||
682 | req->__sector = bio->bi_iter.bi_sector; | |
683 | req->ioprio = bio_prio(bio); | |
684 | req->write_hint = bio->bi_write_hint; | |
685 | blk_rq_bio_prep(req->q, req, bio); | |
686 | } | |
687 | EXPORT_SYMBOL_GPL(blk_init_request_from_bio); | |
688 | ||
689 | static void handle_bad_sector(struct bio *bio, sector_t maxsector) | |
690 | { | |
691 | char b[BDEVNAME_SIZE]; | |
692 | ||
693 | printk(KERN_INFO "attempt to access beyond end of device\n"); | |
694 | printk(KERN_INFO "%s: rw=%d, want=%Lu, limit=%Lu\n", | |
695 | bio_devname(bio, b), bio->bi_opf, | |
696 | (unsigned long long)bio_end_sector(bio), | |
697 | (long long)maxsector); | |
698 | } | |
699 | ||
700 | #ifdef CONFIG_FAIL_MAKE_REQUEST | |
701 | ||
702 | static DECLARE_FAULT_ATTR(fail_make_request); | |
703 | ||
704 | static int __init setup_fail_make_request(char *str) | |
705 | { | |
706 | return setup_fault_attr(&fail_make_request, str); | |
707 | } | |
708 | __setup("fail_make_request=", setup_fail_make_request); | |
709 | ||
710 | static bool should_fail_request(struct hd_struct *part, unsigned int bytes) | |
711 | { | |
712 | return part->make_it_fail && should_fail(&fail_make_request, bytes); | |
713 | } | |
714 | ||
715 | static int __init fail_make_request_debugfs(void) | |
716 | { | |
717 | struct dentry *dir = fault_create_debugfs_attr("fail_make_request", | |
718 | NULL, &fail_make_request); | |
719 | ||
720 | return PTR_ERR_OR_ZERO(dir); | |
721 | } | |
722 | ||
723 | late_initcall(fail_make_request_debugfs); | |
724 | ||
725 | #else /* CONFIG_FAIL_MAKE_REQUEST */ | |
726 | ||
727 | static inline bool should_fail_request(struct hd_struct *part, | |
728 | unsigned int bytes) | |
729 | { | |
730 | return false; | |
731 | } | |
732 | ||
733 | #endif /* CONFIG_FAIL_MAKE_REQUEST */ | |
734 | ||
735 | static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part) | |
736 | { | |
737 | const int op = bio_op(bio); | |
738 | ||
739 | if (part->policy && op_is_write(op)) { | |
740 | char b[BDEVNAME_SIZE]; | |
741 | ||
742 | if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) | |
743 | return false; | |
744 | ||
745 | WARN_ONCE(1, | |
746 | "generic_make_request: Trying to write " | |
747 | "to read-only block-device %s (partno %d)\n", | |
748 | bio_devname(bio, b), part->partno); | |
749 | /* Older lvm-tools actually trigger this */ | |
750 | return false; | |
751 | } | |
752 | ||
753 | return false; | |
754 | } | |
755 | ||
756 | static noinline int should_fail_bio(struct bio *bio) | |
757 | { | |
758 | if (should_fail_request(&bio->bi_disk->part0, bio->bi_iter.bi_size)) | |
759 | return -EIO; | |
760 | return 0; | |
761 | } | |
762 | ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); | |
763 | ||
764 | /* | |
765 | * Check whether this bio extends beyond the end of the device or partition. | |
766 | * This may well happen - the kernel calls bread() without checking the size of | |
767 | * the device, e.g., when mounting a file system. | |
768 | */ | |
769 | static inline int bio_check_eod(struct bio *bio, sector_t maxsector) | |
770 | { | |
771 | unsigned int nr_sectors = bio_sectors(bio); | |
772 | ||
773 | if (nr_sectors && maxsector && | |
774 | (nr_sectors > maxsector || | |
775 | bio->bi_iter.bi_sector > maxsector - nr_sectors)) { | |
776 | handle_bad_sector(bio, maxsector); | |
777 | return -EIO; | |
778 | } | |
779 | return 0; | |
780 | } | |
781 | ||
782 | /* | |
783 | * Remap block n of partition p to block n+start(p) of the disk. | |
784 | */ | |
785 | static inline int blk_partition_remap(struct bio *bio) | |
786 | { | |
787 | struct hd_struct *p; | |
788 | int ret = -EIO; | |
789 | ||
790 | rcu_read_lock(); | |
791 | p = __disk_get_part(bio->bi_disk, bio->bi_partno); | |
792 | if (unlikely(!p)) | |
793 | goto out; | |
794 | if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) | |
795 | goto out; | |
796 | if (unlikely(bio_check_ro(bio, p))) | |
797 | goto out; | |
798 | ||
799 | /* | |
800 | * Zone reset does not include bi_size so bio_sectors() is always 0. | |
801 | * Include a test for the reset op code and perform the remap if needed. | |
802 | */ | |
803 | if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET) { | |
804 | if (bio_check_eod(bio, part_nr_sects_read(p))) | |
805 | goto out; | |
806 | bio->bi_iter.bi_sector += p->start_sect; | |
807 | trace_block_bio_remap(bio->bi_disk->queue, bio, part_devt(p), | |
808 | bio->bi_iter.bi_sector - p->start_sect); | |
809 | } | |
810 | bio->bi_partno = 0; | |
811 | ret = 0; | |
812 | out: | |
813 | rcu_read_unlock(); | |
814 | return ret; | |
815 | } | |
816 | ||
817 | static noinline_for_stack bool | |
818 | generic_make_request_checks(struct bio *bio) | |
819 | { | |
820 | struct request_queue *q; | |
821 | int nr_sectors = bio_sectors(bio); | |
822 | blk_status_t status = BLK_STS_IOERR; | |
823 | char b[BDEVNAME_SIZE]; | |
824 | ||
825 | might_sleep(); | |
826 | ||
827 | q = bio->bi_disk->queue; | |
828 | if (unlikely(!q)) { | |
829 | printk(KERN_ERR | |
830 | "generic_make_request: Trying to access " | |
831 | "nonexistent block-device %s (%Lu)\n", | |
832 | bio_devname(bio, b), (long long)bio->bi_iter.bi_sector); | |
833 | goto end_io; | |
834 | } | |
835 | ||
836 | /* | |
837 | * For a REQ_NOWAIT based request, return -EOPNOTSUPP | |
838 | * if queue is not a request based queue. | |
839 | */ | |
840 | if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_mq(q)) | |
841 | goto not_supported; | |
842 | ||
843 | if (should_fail_bio(bio)) | |
844 | goto end_io; | |
845 | ||
846 | if (bio->bi_partno) { | |
847 | if (unlikely(blk_partition_remap(bio))) | |
848 | goto end_io; | |
849 | } else { | |
850 | if (unlikely(bio_check_ro(bio, &bio->bi_disk->part0))) | |
851 | goto end_io; | |
852 | if (unlikely(bio_check_eod(bio, get_capacity(bio->bi_disk)))) | |
853 | goto end_io; | |
854 | } | |
855 | ||
856 | /* | |
857 | * Filter flush bio's early so that make_request based | |
858 | * drivers without flush support don't have to worry | |
859 | * about them. | |
860 | */ | |
861 | if (op_is_flush(bio->bi_opf) && | |
862 | !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) { | |
863 | bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); | |
864 | if (!nr_sectors) { | |
865 | status = BLK_STS_OK; | |
866 | goto end_io; | |
867 | } | |
868 | } | |
869 | ||
870 | if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) | |
871 | bio->bi_opf &= ~REQ_HIPRI; | |
872 | ||
873 | switch (bio_op(bio)) { | |
874 | case REQ_OP_DISCARD: | |
875 | if (!blk_queue_discard(q)) | |
876 | goto not_supported; | |
877 | break; | |
878 | case REQ_OP_SECURE_ERASE: | |
879 | if (!blk_queue_secure_erase(q)) | |
880 | goto not_supported; | |
881 | break; | |
882 | case REQ_OP_WRITE_SAME: | |
883 | if (!q->limits.max_write_same_sectors) | |
884 | goto not_supported; | |
885 | break; | |
886 | case REQ_OP_ZONE_RESET: | |
887 | if (!blk_queue_is_zoned(q)) | |
888 | goto not_supported; | |
889 | break; | |
890 | case REQ_OP_WRITE_ZEROES: | |
891 | if (!q->limits.max_write_zeroes_sectors) | |
892 | goto not_supported; | |
893 | break; | |
894 | default: | |
895 | break; | |
896 | } | |
897 | ||
898 | /* | |
899 | * Various block parts want %current->io_context and lazy ioc | |
900 | * allocation ends up trading a lot of pain for a small amount of | |
901 | * memory. Just allocate it upfront. This may fail and block | |
902 | * layer knows how to live with it. | |
903 | */ | |
904 | create_io_context(GFP_ATOMIC, q->node); | |
905 | ||
906 | if (!blkcg_bio_issue_check(q, bio)) | |
907 | return false; | |
908 | ||
909 | if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { | |
910 | trace_block_bio_queue(q, bio); | |
911 | /* Now that enqueuing has been traced, we need to trace | |
912 | * completion as well. | |
913 | */ | |
914 | bio_set_flag(bio, BIO_TRACE_COMPLETION); | |
915 | } | |
916 | return true; | |
917 | ||
918 | not_supported: | |
919 | status = BLK_STS_NOTSUPP; | |
920 | end_io: | |
921 | bio->bi_status = status; | |
922 | bio_endio(bio); | |
923 | return false; | |
924 | } | |
925 | ||
926 | /** | |
927 | * generic_make_request - hand a buffer to its device driver for I/O | |
928 | * @bio: The bio describing the location in memory and on the device. | |
929 | * | |
930 | * generic_make_request() is used to make I/O requests of block | |
931 | * devices. It is passed a &struct bio, which describes the I/O that needs | |
932 | * to be done. | |
933 | * | |
934 | * generic_make_request() does not return any status. The | |
935 | * success/failure status of the request, along with notification of | |
936 | * completion, is delivered asynchronously through the bio->bi_end_io | |
937 | * function described (one day) else where. | |
938 | * | |
939 | * The caller of generic_make_request must make sure that bi_io_vec | |
940 | * are set to describe the memory buffer, and that bi_dev and bi_sector are | |
941 | * set to describe the device address, and the | |
942 | * bi_end_io and optionally bi_private are set to describe how | |
943 | * completion notification should be signaled. | |
944 | * | |
945 | * generic_make_request and the drivers it calls may use bi_next if this | |
946 | * bio happens to be merged with someone else, and may resubmit the bio to | |
947 | * a lower device by calling into generic_make_request recursively, which | |
948 | * means the bio should NOT be touched after the call to ->make_request_fn. | |
949 | */ | |
950 | blk_qc_t generic_make_request(struct bio *bio) | |
951 | { | |
952 | /* | |
953 | * bio_list_on_stack[0] contains bios submitted by the current | |
954 | * make_request_fn. | |
955 | * bio_list_on_stack[1] contains bios that were submitted before | |
956 | * the current make_request_fn, but that haven't been processed | |
957 | * yet. | |
958 | */ | |
959 | struct bio_list bio_list_on_stack[2]; | |
960 | blk_qc_t ret = BLK_QC_T_NONE; | |
961 | ||
962 | if (!generic_make_request_checks(bio)) | |
963 | goto out; | |
964 | ||
965 | /* | |
966 | * We only want one ->make_request_fn to be active at a time, else | |
967 | * stack usage with stacked devices could be a problem. So use | |
968 | * current->bio_list to keep a list of requests submited by a | |
969 | * make_request_fn function. current->bio_list is also used as a | |
970 | * flag to say if generic_make_request is currently active in this | |
971 | * task or not. If it is NULL, then no make_request is active. If | |
972 | * it is non-NULL, then a make_request is active, and new requests | |
973 | * should be added at the tail | |
974 | */ | |
975 | if (current->bio_list) { | |
976 | bio_list_add(¤t->bio_list[0], bio); | |
977 | goto out; | |
978 | } | |
979 | ||
980 | /* following loop may be a bit non-obvious, and so deserves some | |
981 | * explanation. | |
982 | * Before entering the loop, bio->bi_next is NULL (as all callers | |
983 | * ensure that) so we have a list with a single bio. | |
984 | * We pretend that we have just taken it off a longer list, so | |
985 | * we assign bio_list to a pointer to the bio_list_on_stack, | |
986 | * thus initialising the bio_list of new bios to be | |
987 | * added. ->make_request() may indeed add some more bios | |
988 | * through a recursive call to generic_make_request. If it | |
989 | * did, we find a non-NULL value in bio_list and re-enter the loop | |
990 | * from the top. In this case we really did just take the bio | |
991 | * of the top of the list (no pretending) and so remove it from | |
992 | * bio_list, and call into ->make_request() again. | |
993 | */ | |
994 | BUG_ON(bio->bi_next); | |
995 | bio_list_init(&bio_list_on_stack[0]); | |
996 | current->bio_list = bio_list_on_stack; | |
997 | do { | |
998 | struct request_queue *q = bio->bi_disk->queue; | |
999 | blk_mq_req_flags_t flags = bio->bi_opf & REQ_NOWAIT ? | |
1000 | BLK_MQ_REQ_NOWAIT : 0; | |
1001 | ||
1002 | if (likely(blk_queue_enter(q, flags) == 0)) { | |
1003 | struct bio_list lower, same; | |
1004 | ||
1005 | /* Create a fresh bio_list for all subordinate requests */ | |
1006 | bio_list_on_stack[1] = bio_list_on_stack[0]; | |
1007 | bio_list_init(&bio_list_on_stack[0]); | |
1008 | ret = q->make_request_fn(q, bio); | |
1009 | ||
1010 | blk_queue_exit(q); | |
1011 | ||
1012 | /* sort new bios into those for a lower level | |
1013 | * and those for the same level | |
1014 | */ | |
1015 | bio_list_init(&lower); | |
1016 | bio_list_init(&same); | |
1017 | while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL) | |
1018 | if (q == bio->bi_disk->queue) | |
1019 | bio_list_add(&same, bio); | |
1020 | else | |
1021 | bio_list_add(&lower, bio); | |
1022 | /* now assemble so we handle the lowest level first */ | |
1023 | bio_list_merge(&bio_list_on_stack[0], &lower); | |
1024 | bio_list_merge(&bio_list_on_stack[0], &same); | |
1025 | bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); | |
1026 | } else { | |
1027 | if (unlikely(!blk_queue_dying(q) && | |
1028 | (bio->bi_opf & REQ_NOWAIT))) | |
1029 | bio_wouldblock_error(bio); | |
1030 | else | |
1031 | bio_io_error(bio); | |
1032 | } | |
1033 | bio = bio_list_pop(&bio_list_on_stack[0]); | |
1034 | } while (bio); | |
1035 | current->bio_list = NULL; /* deactivate */ | |
1036 | ||
1037 | out: | |
1038 | return ret; | |
1039 | } | |
1040 | EXPORT_SYMBOL(generic_make_request); | |
1041 | ||
1042 | /** | |
1043 | * direct_make_request - hand a buffer directly to its device driver for I/O | |
1044 | * @bio: The bio describing the location in memory and on the device. | |
1045 | * | |
1046 | * This function behaves like generic_make_request(), but does not protect | |
1047 | * against recursion. Must only be used if the called driver is known | |
1048 | * to not call generic_make_request (or direct_make_request) again from | |
1049 | * its make_request function. (Calling direct_make_request again from | |
1050 | * a workqueue is perfectly fine as that doesn't recurse). | |
1051 | */ | |
1052 | blk_qc_t direct_make_request(struct bio *bio) | |
1053 | { | |
1054 | struct request_queue *q = bio->bi_disk->queue; | |
1055 | bool nowait = bio->bi_opf & REQ_NOWAIT; | |
1056 | blk_qc_t ret; | |
1057 | ||
1058 | if (!generic_make_request_checks(bio)) | |
1059 | return BLK_QC_T_NONE; | |
1060 | ||
1061 | if (unlikely(blk_queue_enter(q, nowait ? BLK_MQ_REQ_NOWAIT : 0))) { | |
1062 | if (nowait && !blk_queue_dying(q)) | |
1063 | bio->bi_status = BLK_STS_AGAIN; | |
1064 | else | |
1065 | bio->bi_status = BLK_STS_IOERR; | |
1066 | bio_endio(bio); | |
1067 | return BLK_QC_T_NONE; | |
1068 | } | |
1069 | ||
1070 | ret = q->make_request_fn(q, bio); | |
1071 | blk_queue_exit(q); | |
1072 | return ret; | |
1073 | } | |
1074 | EXPORT_SYMBOL_GPL(direct_make_request); | |
1075 | ||
1076 | /** | |
1077 | * submit_bio - submit a bio to the block device layer for I/O | |
1078 | * @bio: The &struct bio which describes the I/O | |
1079 | * | |
1080 | * submit_bio() is very similar in purpose to generic_make_request(), and | |
1081 | * uses that function to do most of the work. Both are fairly rough | |
1082 | * interfaces; @bio must be presetup and ready for I/O. | |
1083 | * | |
1084 | */ | |
1085 | blk_qc_t submit_bio(struct bio *bio) | |
1086 | { | |
1087 | /* | |
1088 | * If it's a regular read/write or a barrier with data attached, | |
1089 | * go through the normal accounting stuff before submission. | |
1090 | */ | |
1091 | if (bio_has_data(bio)) { | |
1092 | unsigned int count; | |
1093 | ||
1094 | if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) | |
1095 | count = queue_logical_block_size(bio->bi_disk->queue) >> 9; | |
1096 | else | |
1097 | count = bio_sectors(bio); | |
1098 | ||
1099 | if (op_is_write(bio_op(bio))) { | |
1100 | count_vm_events(PGPGOUT, count); | |
1101 | } else { | |
1102 | task_io_account_read(bio->bi_iter.bi_size); | |
1103 | count_vm_events(PGPGIN, count); | |
1104 | } | |
1105 | ||
1106 | if (unlikely(block_dump)) { | |
1107 | char b[BDEVNAME_SIZE]; | |
1108 | printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n", | |
1109 | current->comm, task_pid_nr(current), | |
1110 | op_is_write(bio_op(bio)) ? "WRITE" : "READ", | |
1111 | (unsigned long long)bio->bi_iter.bi_sector, | |
1112 | bio_devname(bio, b), count); | |
1113 | } | |
1114 | } | |
1115 | ||
1116 | return generic_make_request(bio); | |
1117 | } | |
1118 | EXPORT_SYMBOL(submit_bio); | |
1119 | ||
1120 | /** | |
1121 | * blk_cloned_rq_check_limits - Helper function to check a cloned request | |
1122 | * for new the queue limits | |
1123 | * @q: the queue | |
1124 | * @rq: the request being checked | |
1125 | * | |
1126 | * Description: | |
1127 | * @rq may have been made based on weaker limitations of upper-level queues | |
1128 | * in request stacking drivers, and it may violate the limitation of @q. | |
1129 | * Since the block layer and the underlying device driver trust @rq | |
1130 | * after it is inserted to @q, it should be checked against @q before | |
1131 | * the insertion using this generic function. | |
1132 | * | |
1133 | * Request stacking drivers like request-based dm may change the queue | |
1134 | * limits when retrying requests on other queues. Those requests need | |
1135 | * to be checked against the new queue limits again during dispatch. | |
1136 | */ | |
1137 | static int blk_cloned_rq_check_limits(struct request_queue *q, | |
1138 | struct request *rq) | |
1139 | { | |
1140 | if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) { | |
1141 | printk(KERN_ERR "%s: over max size limit. (%u > %u)\n", | |
1142 | __func__, blk_rq_sectors(rq), | |
1143 | blk_queue_get_max_sectors(q, req_op(rq))); | |
1144 | return -EIO; | |
1145 | } | |
1146 | ||
1147 | /* | |
1148 | * queue's settings related to segment counting like q->bounce_pfn | |
1149 | * may differ from that of other stacking queues. | |
1150 | * Recalculate it to check the request correctly on this queue's | |
1151 | * limitation. | |
1152 | */ | |
1153 | blk_recalc_rq_segments(rq); | |
1154 | if (rq->nr_phys_segments > queue_max_segments(q)) { | |
1155 | printk(KERN_ERR "%s: over max segments limit. (%hu > %hu)\n", | |
1156 | __func__, rq->nr_phys_segments, queue_max_segments(q)); | |
1157 | return -EIO; | |
1158 | } | |
1159 | ||
1160 | return 0; | |
1161 | } | |
1162 | ||
1163 | /** | |
1164 | * blk_insert_cloned_request - Helper for stacking drivers to submit a request | |
1165 | * @q: the queue to submit the request | |
1166 | * @rq: the request being queued | |
1167 | */ | |
1168 | blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *rq) | |
1169 | { | |
1170 | if (blk_cloned_rq_check_limits(q, rq)) | |
1171 | return BLK_STS_IOERR; | |
1172 | ||
1173 | if (rq->rq_disk && | |
1174 | should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq))) | |
1175 | return BLK_STS_IOERR; | |
1176 | ||
1177 | if (blk_queue_io_stat(q)) | |
1178 | blk_account_io_start(rq, true); | |
1179 | ||
1180 | /* | |
1181 | * Since we have a scheduler attached on the top device, | |
1182 | * bypass a potential scheduler on the bottom device for | |
1183 | * insert. | |
1184 | */ | |
1185 | return blk_mq_request_issue_directly(rq, true); | |
1186 | } | |
1187 | EXPORT_SYMBOL_GPL(blk_insert_cloned_request); | |
1188 | ||
1189 | /** | |
1190 | * blk_rq_err_bytes - determine number of bytes till the next failure boundary | |
1191 | * @rq: request to examine | |
1192 | * | |
1193 | * Description: | |
1194 | * A request could be merge of IOs which require different failure | |
1195 | * handling. This function determines the number of bytes which | |
1196 | * can be failed from the beginning of the request without | |
1197 | * crossing into area which need to be retried further. | |
1198 | * | |
1199 | * Return: | |
1200 | * The number of bytes to fail. | |
1201 | */ | |
1202 | unsigned int blk_rq_err_bytes(const struct request *rq) | |
1203 | { | |
1204 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; | |
1205 | unsigned int bytes = 0; | |
1206 | struct bio *bio; | |
1207 | ||
1208 | if (!(rq->rq_flags & RQF_MIXED_MERGE)) | |
1209 | return blk_rq_bytes(rq); | |
1210 | ||
1211 | /* | |
1212 | * Currently the only 'mixing' which can happen is between | |
1213 | * different fastfail types. We can safely fail portions | |
1214 | * which have all the failfast bits that the first one has - | |
1215 | * the ones which are at least as eager to fail as the first | |
1216 | * one. | |
1217 | */ | |
1218 | for (bio = rq->bio; bio; bio = bio->bi_next) { | |
1219 | if ((bio->bi_opf & ff) != ff) | |
1220 | break; | |
1221 | bytes += bio->bi_iter.bi_size; | |
1222 | } | |
1223 | ||
1224 | /* this could lead to infinite loop */ | |
1225 | BUG_ON(blk_rq_bytes(rq) && !bytes); | |
1226 | return bytes; | |
1227 | } | |
1228 | EXPORT_SYMBOL_GPL(blk_rq_err_bytes); | |
1229 | ||
1230 | void blk_account_io_completion(struct request *req, unsigned int bytes) | |
1231 | { | |
1232 | if (blk_do_io_stat(req)) { | |
1233 | const int sgrp = op_stat_group(req_op(req)); | |
1234 | struct hd_struct *part; | |
1235 | ||
1236 | part_stat_lock(); | |
1237 | part = req->part; | |
1238 | part_stat_add(part, sectors[sgrp], bytes >> 9); | |
1239 | part_stat_unlock(); | |
1240 | } | |
1241 | } | |
1242 | ||
1243 | void blk_account_io_done(struct request *req, u64 now) | |
1244 | { | |
1245 | /* | |
1246 | * Account IO completion. flush_rq isn't accounted as a | |
1247 | * normal IO on queueing nor completion. Accounting the | |
1248 | * containing request is enough. | |
1249 | */ | |
1250 | if (blk_do_io_stat(req) && !(req->rq_flags & RQF_FLUSH_SEQ)) { | |
1251 | const int sgrp = op_stat_group(req_op(req)); | |
1252 | struct hd_struct *part; | |
1253 | ||
1254 | part_stat_lock(); | |
1255 | part = req->part; | |
1256 | ||
1257 | update_io_ticks(part, jiffies); | |
1258 | part_stat_inc(part, ios[sgrp]); | |
1259 | part_stat_add(part, nsecs[sgrp], now - req->start_time_ns); | |
1260 | part_stat_add(part, time_in_queue, nsecs_to_jiffies64(now - req->start_time_ns)); | |
1261 | part_dec_in_flight(req->q, part, rq_data_dir(req)); | |
1262 | ||
1263 | hd_struct_put(part); | |
1264 | part_stat_unlock(); | |
1265 | } | |
1266 | } | |
1267 | ||
1268 | void blk_account_io_start(struct request *rq, bool new_io) | |
1269 | { | |
1270 | struct hd_struct *part; | |
1271 | int rw = rq_data_dir(rq); | |
1272 | ||
1273 | if (!blk_do_io_stat(rq)) | |
1274 | return; | |
1275 | ||
1276 | part_stat_lock(); | |
1277 | ||
1278 | if (!new_io) { | |
1279 | part = rq->part; | |
1280 | part_stat_inc(part, merges[rw]); | |
1281 | } else { | |
1282 | part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); | |
1283 | if (!hd_struct_try_get(part)) { | |
1284 | /* | |
1285 | * The partition is already being removed, | |
1286 | * the request will be accounted on the disk only | |
1287 | * | |
1288 | * We take a reference on disk->part0 although that | |
1289 | * partition will never be deleted, so we can treat | |
1290 | * it as any other partition. | |
1291 | */ | |
1292 | part = &rq->rq_disk->part0; | |
1293 | hd_struct_get(part); | |
1294 | } | |
1295 | part_inc_in_flight(rq->q, part, rw); | |
1296 | rq->part = part; | |
1297 | } | |
1298 | ||
1299 | update_io_ticks(part, jiffies); | |
1300 | ||
1301 | part_stat_unlock(); | |
1302 | } | |
1303 | ||
1304 | /* | |
1305 | * Steal bios from a request and add them to a bio list. | |
1306 | * The request must not have been partially completed before. | |
1307 | */ | |
1308 | void blk_steal_bios(struct bio_list *list, struct request *rq) | |
1309 | { | |
1310 | if (rq->bio) { | |
1311 | if (list->tail) | |
1312 | list->tail->bi_next = rq->bio; | |
1313 | else | |
1314 | list->head = rq->bio; | |
1315 | list->tail = rq->biotail; | |
1316 | ||
1317 | rq->bio = NULL; | |
1318 | rq->biotail = NULL; | |
1319 | } | |
1320 | ||
1321 | rq->__data_len = 0; | |
1322 | } | |
1323 | EXPORT_SYMBOL_GPL(blk_steal_bios); | |
1324 | ||
1325 | /** | |
1326 | * blk_update_request - Special helper function for request stacking drivers | |
1327 | * @req: the request being processed | |
1328 | * @error: block status code | |
1329 | * @nr_bytes: number of bytes to complete @req | |
1330 | * | |
1331 | * Description: | |
1332 | * Ends I/O on a number of bytes attached to @req, but doesn't complete | |
1333 | * the request structure even if @req doesn't have leftover. | |
1334 | * If @req has leftover, sets it up for the next range of segments. | |
1335 | * | |
1336 | * This special helper function is only for request stacking drivers | |
1337 | * (e.g. request-based dm) so that they can handle partial completion. | |
1338 | * Actual device drivers should use blk_end_request instead. | |
1339 | * | |
1340 | * Passing the result of blk_rq_bytes() as @nr_bytes guarantees | |
1341 | * %false return from this function. | |
1342 | * | |
1343 | * Note: | |
1344 | * The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in both | |
1345 | * blk_rq_bytes() and in blk_update_request(). | |
1346 | * | |
1347 | * Return: | |
1348 | * %false - this request doesn't have any more data | |
1349 | * %true - this request has more data | |
1350 | **/ | |
1351 | bool blk_update_request(struct request *req, blk_status_t error, | |
1352 | unsigned int nr_bytes) | |
1353 | { | |
1354 | int total_bytes; | |
1355 | ||
1356 | trace_block_rq_complete(req, blk_status_to_errno(error), nr_bytes); | |
1357 | ||
1358 | if (!req->bio) | |
1359 | return false; | |
1360 | ||
1361 | if (unlikely(error && !blk_rq_is_passthrough(req) && | |
1362 | !(req->rq_flags & RQF_QUIET))) | |
1363 | print_req_error(req, error); | |
1364 | ||
1365 | blk_account_io_completion(req, nr_bytes); | |
1366 | ||
1367 | total_bytes = 0; | |
1368 | while (req->bio) { | |
1369 | struct bio *bio = req->bio; | |
1370 | unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes); | |
1371 | ||
1372 | if (bio_bytes == bio->bi_iter.bi_size) | |
1373 | req->bio = bio->bi_next; | |
1374 | ||
1375 | /* Completion has already been traced */ | |
1376 | bio_clear_flag(bio, BIO_TRACE_COMPLETION); | |
1377 | req_bio_endio(req, bio, bio_bytes, error); | |
1378 | ||
1379 | total_bytes += bio_bytes; | |
1380 | nr_bytes -= bio_bytes; | |
1381 | ||
1382 | if (!nr_bytes) | |
1383 | break; | |
1384 | } | |
1385 | ||
1386 | /* | |
1387 | * completely done | |
1388 | */ | |
1389 | if (!req->bio) { | |
1390 | /* | |
1391 | * Reset counters so that the request stacking driver | |
1392 | * can find how many bytes remain in the request | |
1393 | * later. | |
1394 | */ | |
1395 | req->__data_len = 0; | |
1396 | return false; | |
1397 | } | |
1398 | ||
1399 | req->__data_len -= total_bytes; | |
1400 | ||
1401 | /* update sector only for requests with clear definition of sector */ | |
1402 | if (!blk_rq_is_passthrough(req)) | |
1403 | req->__sector += total_bytes >> 9; | |
1404 | ||
1405 | /* mixed attributes always follow the first bio */ | |
1406 | if (req->rq_flags & RQF_MIXED_MERGE) { | |
1407 | req->cmd_flags &= ~REQ_FAILFAST_MASK; | |
1408 | req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK; | |
1409 | } | |
1410 | ||
1411 | if (!(req->rq_flags & RQF_SPECIAL_PAYLOAD)) { | |
1412 | /* | |
1413 | * If total number of sectors is less than the first segment | |
1414 | * size, something has gone terribly wrong. | |
1415 | */ | |
1416 | if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { | |
1417 | blk_dump_rq_flags(req, "request botched"); | |
1418 | req->__data_len = blk_rq_cur_bytes(req); | |
1419 | } | |
1420 | ||
1421 | /* recalculate the number of segments */ | |
1422 | blk_recalc_rq_segments(req); | |
1423 | } | |
1424 | ||
1425 | return true; | |
1426 | } | |
1427 | EXPORT_SYMBOL_GPL(blk_update_request); | |
1428 | ||
1429 | void blk_rq_bio_prep(struct request_queue *q, struct request *rq, | |
1430 | struct bio *bio) | |
1431 | { | |
1432 | if (bio_has_data(bio)) | |
1433 | rq->nr_phys_segments = bio_phys_segments(q, bio); | |
1434 | else if (bio_op(bio) == REQ_OP_DISCARD) | |
1435 | rq->nr_phys_segments = 1; | |
1436 | ||
1437 | rq->__data_len = bio->bi_iter.bi_size; | |
1438 | rq->bio = rq->biotail = bio; | |
1439 | ||
1440 | if (bio->bi_disk) | |
1441 | rq->rq_disk = bio->bi_disk; | |
1442 | } | |
1443 | ||
1444 | #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE | |
1445 | /** | |
1446 | * rq_flush_dcache_pages - Helper function to flush all pages in a request | |
1447 | * @rq: the request to be flushed | |
1448 | * | |
1449 | * Description: | |
1450 | * Flush all pages in @rq. | |
1451 | */ | |
1452 | void rq_flush_dcache_pages(struct request *rq) | |
1453 | { | |
1454 | struct req_iterator iter; | |
1455 | struct bio_vec bvec; | |
1456 | ||
1457 | rq_for_each_segment(bvec, rq, iter) | |
1458 | flush_dcache_page(bvec.bv_page); | |
1459 | } | |
1460 | EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); | |
1461 | #endif | |
1462 | ||
1463 | /** | |
1464 | * blk_lld_busy - Check if underlying low-level drivers of a device are busy | |
1465 | * @q : the queue of the device being checked | |
1466 | * | |
1467 | * Description: | |
1468 | * Check if underlying low-level drivers of a device are busy. | |
1469 | * If the drivers want to export their busy state, they must set own | |
1470 | * exporting function using blk_queue_lld_busy() first. | |
1471 | * | |
1472 | * Basically, this function is used only by request stacking drivers | |
1473 | * to stop dispatching requests to underlying devices when underlying | |
1474 | * devices are busy. This behavior helps more I/O merging on the queue | |
1475 | * of the request stacking driver and prevents I/O throughput regression | |
1476 | * on burst I/O load. | |
1477 | * | |
1478 | * Return: | |
1479 | * 0 - Not busy (The request stacking driver should dispatch request) | |
1480 | * 1 - Busy (The request stacking driver should stop dispatching request) | |
1481 | */ | |
1482 | int blk_lld_busy(struct request_queue *q) | |
1483 | { | |
1484 | if (queue_is_mq(q) && q->mq_ops->busy) | |
1485 | return q->mq_ops->busy(q); | |
1486 | ||
1487 | return 0; | |
1488 | } | |
1489 | EXPORT_SYMBOL_GPL(blk_lld_busy); | |
1490 | ||
1491 | /** | |
1492 | * blk_rq_unprep_clone - Helper function to free all bios in a cloned request | |
1493 | * @rq: the clone request to be cleaned up | |
1494 | * | |
1495 | * Description: | |
1496 | * Free all bios in @rq for a cloned request. | |
1497 | */ | |
1498 | void blk_rq_unprep_clone(struct request *rq) | |
1499 | { | |
1500 | struct bio *bio; | |
1501 | ||
1502 | while ((bio = rq->bio) != NULL) { | |
1503 | rq->bio = bio->bi_next; | |
1504 | ||
1505 | bio_put(bio); | |
1506 | } | |
1507 | } | |
1508 | EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); | |
1509 | ||
1510 | /* | |
1511 | * Copy attributes of the original request to the clone request. | |
1512 | * The actual data parts (e.g. ->cmd, ->sense) are not copied. | |
1513 | */ | |
1514 | static void __blk_rq_prep_clone(struct request *dst, struct request *src) | |
1515 | { | |
1516 | dst->__sector = blk_rq_pos(src); | |
1517 | dst->__data_len = blk_rq_bytes(src); | |
1518 | if (src->rq_flags & RQF_SPECIAL_PAYLOAD) { | |
1519 | dst->rq_flags |= RQF_SPECIAL_PAYLOAD; | |
1520 | dst->special_vec = src->special_vec; | |
1521 | } | |
1522 | dst->nr_phys_segments = src->nr_phys_segments; | |
1523 | dst->ioprio = src->ioprio; | |
1524 | dst->extra_len = src->extra_len; | |
1525 | } | |
1526 | ||
1527 | /** | |
1528 | * blk_rq_prep_clone - Helper function to setup clone request | |
1529 | * @rq: the request to be setup | |
1530 | * @rq_src: original request to be cloned | |
1531 | * @bs: bio_set that bios for clone are allocated from | |
1532 | * @gfp_mask: memory allocation mask for bio | |
1533 | * @bio_ctr: setup function to be called for each clone bio. | |
1534 | * Returns %0 for success, non %0 for failure. | |
1535 | * @data: private data to be passed to @bio_ctr | |
1536 | * | |
1537 | * Description: | |
1538 | * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. | |
1539 | * The actual data parts of @rq_src (e.g. ->cmd, ->sense) | |
1540 | * are not copied, and copying such parts is the caller's responsibility. | |
1541 | * Also, pages which the original bios are pointing to are not copied | |
1542 | * and the cloned bios just point same pages. | |
1543 | * So cloned bios must be completed before original bios, which means | |
1544 | * the caller must complete @rq before @rq_src. | |
1545 | */ | |
1546 | int blk_rq_prep_clone(struct request *rq, struct request *rq_src, | |
1547 | struct bio_set *bs, gfp_t gfp_mask, | |
1548 | int (*bio_ctr)(struct bio *, struct bio *, void *), | |
1549 | void *data) | |
1550 | { | |
1551 | struct bio *bio, *bio_src; | |
1552 | ||
1553 | if (!bs) | |
1554 | bs = &fs_bio_set; | |
1555 | ||
1556 | __rq_for_each_bio(bio_src, rq_src) { | |
1557 | bio = bio_clone_fast(bio_src, gfp_mask, bs); | |
1558 | if (!bio) | |
1559 | goto free_and_out; | |
1560 | ||
1561 | if (bio_ctr && bio_ctr(bio, bio_src, data)) | |
1562 | goto free_and_out; | |
1563 | ||
1564 | if (rq->bio) { | |
1565 | rq->biotail->bi_next = bio; | |
1566 | rq->biotail = bio; | |
1567 | } else | |
1568 | rq->bio = rq->biotail = bio; | |
1569 | } | |
1570 | ||
1571 | __blk_rq_prep_clone(rq, rq_src); | |
1572 | ||
1573 | return 0; | |
1574 | ||
1575 | free_and_out: | |
1576 | if (bio) | |
1577 | bio_put(bio); | |
1578 | blk_rq_unprep_clone(rq); | |
1579 | ||
1580 | return -ENOMEM; | |
1581 | } | |
1582 | EXPORT_SYMBOL_GPL(blk_rq_prep_clone); | |
1583 | ||
1584 | int kblockd_schedule_work(struct work_struct *work) | |
1585 | { | |
1586 | return queue_work(kblockd_workqueue, work); | |
1587 | } | |
1588 | EXPORT_SYMBOL(kblockd_schedule_work); | |
1589 | ||
1590 | int kblockd_schedule_work_on(int cpu, struct work_struct *work) | |
1591 | { | |
1592 | return queue_work_on(cpu, kblockd_workqueue, work); | |
1593 | } | |
1594 | EXPORT_SYMBOL(kblockd_schedule_work_on); | |
1595 | ||
1596 | int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, | |
1597 | unsigned long delay) | |
1598 | { | |
1599 | return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); | |
1600 | } | |
1601 | EXPORT_SYMBOL(kblockd_mod_delayed_work_on); | |
1602 | ||
1603 | /** | |
1604 | * blk_start_plug - initialize blk_plug and track it inside the task_struct | |
1605 | * @plug: The &struct blk_plug that needs to be initialized | |
1606 | * | |
1607 | * Description: | |
1608 | * blk_start_plug() indicates to the block layer an intent by the caller | |
1609 | * to submit multiple I/O requests in a batch. The block layer may use | |
1610 | * this hint to defer submitting I/Os from the caller until blk_finish_plug() | |
1611 | * is called. However, the block layer may choose to submit requests | |
1612 | * before a call to blk_finish_plug() if the number of queued I/Os | |
1613 | * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than | |
1614 | * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if | |
1615 | * the task schedules (see below). | |
1616 | * | |
1617 | * Tracking blk_plug inside the task_struct will help with auto-flushing the | |
1618 | * pending I/O should the task end up blocking between blk_start_plug() and | |
1619 | * blk_finish_plug(). This is important from a performance perspective, but | |
1620 | * also ensures that we don't deadlock. For instance, if the task is blocking | |
1621 | * for a memory allocation, memory reclaim could end up wanting to free a | |
1622 | * page belonging to that request that is currently residing in our private | |
1623 | * plug. By flushing the pending I/O when the process goes to sleep, we avoid | |
1624 | * this kind of deadlock. | |
1625 | */ | |
1626 | void blk_start_plug(struct blk_plug *plug) | |
1627 | { | |
1628 | struct task_struct *tsk = current; | |
1629 | ||
1630 | /* | |
1631 | * If this is a nested plug, don't actually assign it. | |
1632 | */ | |
1633 | if (tsk->plug) | |
1634 | return; | |
1635 | ||
1636 | INIT_LIST_HEAD(&plug->mq_list); | |
1637 | INIT_LIST_HEAD(&plug->cb_list); | |
1638 | plug->rq_count = 0; | |
1639 | plug->multiple_queues = false; | |
1640 | ||
1641 | /* | |
1642 | * Store ordering should not be needed here, since a potential | |
1643 | * preempt will imply a full memory barrier | |
1644 | */ | |
1645 | tsk->plug = plug; | |
1646 | } | |
1647 | EXPORT_SYMBOL(blk_start_plug); | |
1648 | ||
1649 | static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) | |
1650 | { | |
1651 | LIST_HEAD(callbacks); | |
1652 | ||
1653 | while (!list_empty(&plug->cb_list)) { | |
1654 | list_splice_init(&plug->cb_list, &callbacks); | |
1655 | ||
1656 | while (!list_empty(&callbacks)) { | |
1657 | struct blk_plug_cb *cb = list_first_entry(&callbacks, | |
1658 | struct blk_plug_cb, | |
1659 | list); | |
1660 | list_del(&cb->list); | |
1661 | cb->callback(cb, from_schedule); | |
1662 | } | |
1663 | } | |
1664 | } | |
1665 | ||
1666 | struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, | |
1667 | int size) | |
1668 | { | |
1669 | struct blk_plug *plug = current->plug; | |
1670 | struct blk_plug_cb *cb; | |
1671 | ||
1672 | if (!plug) | |
1673 | return NULL; | |
1674 | ||
1675 | list_for_each_entry(cb, &plug->cb_list, list) | |
1676 | if (cb->callback == unplug && cb->data == data) | |
1677 | return cb; | |
1678 | ||
1679 | /* Not currently on the callback list */ | |
1680 | BUG_ON(size < sizeof(*cb)); | |
1681 | cb = kzalloc(size, GFP_ATOMIC); | |
1682 | if (cb) { | |
1683 | cb->data = data; | |
1684 | cb->callback = unplug; | |
1685 | list_add(&cb->list, &plug->cb_list); | |
1686 | } | |
1687 | return cb; | |
1688 | } | |
1689 | EXPORT_SYMBOL(blk_check_plugged); | |
1690 | ||
1691 | void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) | |
1692 | { | |
1693 | flush_plug_callbacks(plug, from_schedule); | |
1694 | ||
1695 | if (!list_empty(&plug->mq_list)) | |
1696 | blk_mq_flush_plug_list(plug, from_schedule); | |
1697 | } | |
1698 | ||
1699 | /** | |
1700 | * blk_finish_plug - mark the end of a batch of submitted I/O | |
1701 | * @plug: The &struct blk_plug passed to blk_start_plug() | |
1702 | * | |
1703 | * Description: | |
1704 | * Indicate that a batch of I/O submissions is complete. This function | |
1705 | * must be paired with an initial call to blk_start_plug(). The intent | |
1706 | * is to allow the block layer to optimize I/O submission. See the | |
1707 | * documentation for blk_start_plug() for more information. | |
1708 | */ | |
1709 | void blk_finish_plug(struct blk_plug *plug) | |
1710 | { | |
1711 | if (plug != current->plug) | |
1712 | return; | |
1713 | blk_flush_plug_list(plug, false); | |
1714 | ||
1715 | current->plug = NULL; | |
1716 | } | |
1717 | EXPORT_SYMBOL(blk_finish_plug); | |
1718 | ||
1719 | int __init blk_dev_init(void) | |
1720 | { | |
1721 | BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS)); | |
1722 | BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * | |
1723 | FIELD_SIZEOF(struct request, cmd_flags)); | |
1724 | BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * | |
1725 | FIELD_SIZEOF(struct bio, bi_opf)); | |
1726 | ||
1727 | /* used for unplugging and affects IO latency/throughput - HIGHPRI */ | |
1728 | kblockd_workqueue = alloc_workqueue("kblockd", | |
1729 | WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); | |
1730 | if (!kblockd_workqueue) | |
1731 | panic("Failed to create kblockd\n"); | |
1732 | ||
1733 | blk_requestq_cachep = kmem_cache_create("request_queue", | |
1734 | sizeof(struct request_queue), 0, SLAB_PANIC, NULL); | |
1735 | ||
1736 | #ifdef CONFIG_DEBUG_FS | |
1737 | blk_debugfs_root = debugfs_create_dir("block", NULL); | |
1738 | #endif | |
1739 | ||
1740 | return 0; | |
1741 | } |