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1 | /* |
2 | * Copyright (C) 1991, 1992 Linus Torvalds |
3 | * Copyright (C) 1994, Karl Keyte: Added support for disk statistics |
4 | * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE |
5 | * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de> |
6 | * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> |
7 | * - July2000 |
8 | * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001 |
9 | */ |
10 | |
11 | /* |
12 | * This handles all read/write requests to block devices |
13 | */ |
14 | #include <linux/kernel.h> |
15 | #include <linux/module.h> |
16 | #include <linux/backing-dev.h> |
17 | #include <linux/bio.h> |
18 | #include <linux/blkdev.h> |
19 | #include <linux/blk-mq.h> |
20 | #include <linux/highmem.h> |
21 | #include <linux/mm.h> |
22 | #include <linux/kernel_stat.h> |
23 | #include <linux/string.h> |
24 | #include <linux/init.h> |
25 | #include <linux/completion.h> |
26 | #include <linux/slab.h> |
27 | #include <linux/swap.h> |
28 | #include <linux/writeback.h> |
29 | #include <linux/task_io_accounting_ops.h> |
30 | #include <linux/fault-inject.h> |
31 | #include <linux/list_sort.h> |
32 | #include <linux/delay.h> |
33 | #include <linux/ratelimit.h> |
34 | #include <linux/pm_runtime.h> |
35 | |
36 | #define CREATE_TRACE_POINTS |
37 | #include <trace/events/block.h> |
38 | |
39 | #include "blk.h" |
40 | #include "blk-cgroup.h" |
41 | #include "blk-mq.h" |
42 | |
43 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); |
44 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); |
45 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); |
46 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug); |
47 | |
48 | DEFINE_IDA(blk_queue_ida); |
49 | |
50 | /* |
51 | * For the allocated request tables |
52 | */ |
53 | struct kmem_cache *request_cachep = NULL; |
54 | |
55 | /* |
56 | * For queue allocation |
57 | */ |
58 | struct kmem_cache *blk_requestq_cachep; |
59 | |
60 | /* |
61 | * Controlling structure to kblockd |
62 | */ |
63 | static struct workqueue_struct *kblockd_workqueue; |
64 | |
65 | void blk_queue_congestion_threshold(struct request_queue *q) |
66 | { |
67 | int nr; |
68 | |
69 | nr = q->nr_requests - (q->nr_requests / 8) + 1; |
70 | if (nr > q->nr_requests) |
71 | nr = q->nr_requests; |
72 | q->nr_congestion_on = nr; |
73 | |
74 | nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1; |
75 | if (nr < 1) |
76 | nr = 1; |
77 | q->nr_congestion_off = nr; |
78 | } |
79 | |
80 | /** |
81 | * blk_get_backing_dev_info - get the address of a queue's backing_dev_info |
82 | * @bdev: device |
83 | * |
84 | * Locates the passed device's request queue and returns the address of its |
85 | * backing_dev_info |
86 | * |
87 | * Will return NULL if the request queue cannot be located. |
88 | */ |
89 | struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) |
90 | { |
91 | struct backing_dev_info *ret = NULL; |
92 | struct request_queue *q = bdev_get_queue(bdev); |
93 | |
94 | if (q) |
95 | ret = &q->backing_dev_info; |
96 | return ret; |
97 | } |
98 | EXPORT_SYMBOL(blk_get_backing_dev_info); |
99 | |
100 | void blk_rq_init(struct request_queue *q, struct request *rq) |
101 | { |
102 | memset(rq, 0, sizeof(*rq)); |
103 | |
104 | INIT_LIST_HEAD(&rq->queuelist); |
105 | INIT_LIST_HEAD(&rq->timeout_list); |
106 | rq->cpu = -1; |
107 | rq->q = q; |
108 | rq->__sector = (sector_t) -1; |
109 | INIT_HLIST_NODE(&rq->hash); |
110 | RB_CLEAR_NODE(&rq->rb_node); |
111 | rq->cmd = rq->__cmd; |
112 | rq->cmd_len = BLK_MAX_CDB; |
113 | rq->tag = -1; |
114 | rq->start_time = jiffies; |
115 | set_start_time_ns(rq); |
116 | rq->part = NULL; |
117 | } |
118 | EXPORT_SYMBOL(blk_rq_init); |
119 | |
120 | static void req_bio_endio(struct request *rq, struct bio *bio, |
121 | unsigned int nbytes, int error) |
122 | { |
123 | if (error) |
124 | clear_bit(BIO_UPTODATE, &bio->bi_flags); |
125 | else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) |
126 | error = -EIO; |
127 | |
128 | if (unlikely(rq->cmd_flags & REQ_QUIET)) |
129 | set_bit(BIO_QUIET, &bio->bi_flags); |
130 | |
131 | bio_advance(bio, nbytes); |
132 | |
133 | /* don't actually finish bio if it's part of flush sequence */ |
134 | if (bio->bi_iter.bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ)) |
135 | bio_endio(bio, error); |
136 | } |
137 | |
138 | void blk_dump_rq_flags(struct request *rq, char *msg) |
139 | { |
140 | int bit; |
141 | |
142 | printk(KERN_INFO "%s: dev %s: type=%x, flags=%llx\n", msg, |
143 | rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type, |
144 | (unsigned long long) rq->cmd_flags); |
145 | |
146 | printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", |
147 | (unsigned long long)blk_rq_pos(rq), |
148 | blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); |
149 | printk(KERN_INFO " bio %p, biotail %p, buffer %p, len %u\n", |
150 | rq->bio, rq->biotail, rq->buffer, blk_rq_bytes(rq)); |
151 | |
152 | if (rq->cmd_type == REQ_TYPE_BLOCK_PC) { |
153 | printk(KERN_INFO " cdb: "); |
154 | for (bit = 0; bit < BLK_MAX_CDB; bit++) |
155 | printk("%02x ", rq->cmd[bit]); |
156 | printk("\n"); |
157 | } |
158 | } |
159 | EXPORT_SYMBOL(blk_dump_rq_flags); |
160 | |
161 | static void blk_delay_work(struct work_struct *work) |
162 | { |
163 | struct request_queue *q; |
164 | |
165 | q = container_of(work, struct request_queue, delay_work.work); |
166 | spin_lock_irq(q->queue_lock); |
167 | __blk_run_queue(q); |
168 | spin_unlock_irq(q->queue_lock); |
169 | } |
170 | |
171 | /** |
172 | * blk_delay_queue - restart queueing after defined interval |
173 | * @q: The &struct request_queue in question |
174 | * @msecs: Delay in msecs |
175 | * |
176 | * Description: |
177 | * Sometimes queueing needs to be postponed for a little while, to allow |
178 | * resources to come back. This function will make sure that queueing is |
179 | * restarted around the specified time. Queue lock must be held. |
180 | */ |
181 | void blk_delay_queue(struct request_queue *q, unsigned long msecs) |
182 | { |
183 | if (likely(!blk_queue_dead(q))) |
184 | queue_delayed_work(kblockd_workqueue, &q->delay_work, |
185 | msecs_to_jiffies(msecs)); |
186 | } |
187 | EXPORT_SYMBOL(blk_delay_queue); |
188 | |
189 | /** |
190 | * blk_start_queue - restart a previously stopped queue |
191 | * @q: The &struct request_queue in question |
192 | * |
193 | * Description: |
194 | * blk_start_queue() will clear the stop flag on the queue, and call |
195 | * the request_fn for the queue if it was in a stopped state when |
196 | * entered. Also see blk_stop_queue(). Queue lock must be held. |
197 | **/ |
198 | void blk_start_queue(struct request_queue *q) |
199 | { |
200 | WARN_ON(!irqs_disabled()); |
201 | |
202 | queue_flag_clear(QUEUE_FLAG_STOPPED, q); |
203 | __blk_run_queue(q); |
204 | } |
205 | EXPORT_SYMBOL(blk_start_queue); |
206 | |
207 | /** |
208 | * blk_stop_queue - stop a queue |
209 | * @q: The &struct request_queue in question |
210 | * |
211 | * Description: |
212 | * The Linux block layer assumes that a block driver will consume all |
213 | * entries on the request queue when the request_fn strategy is called. |
214 | * Often this will not happen, because of hardware limitations (queue |
215 | * depth settings). If a device driver gets a 'queue full' response, |
216 | * or if it simply chooses not to queue more I/O at one point, it can |
217 | * call this function to prevent the request_fn from being called until |
218 | * the driver has signalled it's ready to go again. This happens by calling |
219 | * blk_start_queue() to restart queue operations. Queue lock must be held. |
220 | **/ |
221 | void blk_stop_queue(struct request_queue *q) |
222 | { |
223 | cancel_delayed_work(&q->delay_work); |
224 | queue_flag_set(QUEUE_FLAG_STOPPED, q); |
225 | } |
226 | EXPORT_SYMBOL(blk_stop_queue); |
227 | |
228 | /** |
229 | * blk_sync_queue - cancel any pending callbacks on a queue |
230 | * @q: the queue |
231 | * |
232 | * Description: |
233 | * The block layer may perform asynchronous callback activity |
234 | * on a queue, such as calling the unplug function after a timeout. |
235 | * A block device may call blk_sync_queue to ensure that any |
236 | * such activity is cancelled, thus allowing it to release resources |
237 | * that the callbacks might use. The caller must already have made sure |
238 | * that its ->make_request_fn will not re-add plugging prior to calling |
239 | * this function. |
240 | * |
241 | * This function does not cancel any asynchronous activity arising |
242 | * out of elevator or throttling code. That would require elevaotor_exit() |
243 | * and blkcg_exit_queue() to be called with queue lock initialized. |
244 | * |
245 | */ |
246 | void blk_sync_queue(struct request_queue *q) |
247 | { |
248 | del_timer_sync(&q->timeout); |
249 | |
250 | if (q->mq_ops) { |
251 | struct blk_mq_hw_ctx *hctx; |
252 | int i; |
253 | |
254 | queue_for_each_hw_ctx(q, hctx, i) |
255 | cancel_delayed_work_sync(&hctx->delayed_work); |
256 | } else { |
257 | cancel_delayed_work_sync(&q->delay_work); |
258 | } |
259 | } |
260 | EXPORT_SYMBOL(blk_sync_queue); |
261 | |
262 | /** |
263 | * __blk_run_queue_uncond - run a queue whether or not it has been stopped |
264 | * @q: The queue to run |
265 | * |
266 | * Description: |
267 | * Invoke request handling on a queue if there are any pending requests. |
268 | * May be used to restart request handling after a request has completed. |
269 | * This variant runs the queue whether or not the queue has been |
270 | * stopped. Must be called with the queue lock held and interrupts |
271 | * disabled. See also @blk_run_queue. |
272 | */ |
273 | inline void __blk_run_queue_uncond(struct request_queue *q) |
274 | { |
275 | if (unlikely(blk_queue_dead(q))) |
276 | return; |
277 | |
278 | /* |
279 | * Some request_fn implementations, e.g. scsi_request_fn(), unlock |
280 | * the queue lock internally. As a result multiple threads may be |
281 | * running such a request function concurrently. Keep track of the |
282 | * number of active request_fn invocations such that blk_drain_queue() |
283 | * can wait until all these request_fn calls have finished. |
284 | */ |
285 | q->request_fn_active++; |
286 | q->request_fn(q); |
287 | q->request_fn_active--; |
288 | } |
289 | |
290 | /** |
291 | * __blk_run_queue - run a single device queue |
292 | * @q: The queue to run |
293 | * |
294 | * Description: |
295 | * See @blk_run_queue. This variant must be called with the queue lock |
296 | * held and interrupts disabled. |
297 | */ |
298 | void __blk_run_queue(struct request_queue *q) |
299 | { |
300 | if (unlikely(blk_queue_stopped(q))) |
301 | return; |
302 | |
303 | __blk_run_queue_uncond(q); |
304 | } |
305 | EXPORT_SYMBOL(__blk_run_queue); |
306 | |
307 | /** |
308 | * blk_run_queue_async - run a single device queue in workqueue context |
309 | * @q: The queue to run |
310 | * |
311 | * Description: |
312 | * Tells kblockd to perform the equivalent of @blk_run_queue on behalf |
313 | * of us. The caller must hold the queue lock. |
314 | */ |
315 | void blk_run_queue_async(struct request_queue *q) |
316 | { |
317 | if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q))) |
318 | mod_delayed_work(kblockd_workqueue, &q->delay_work, 0); |
319 | } |
320 | EXPORT_SYMBOL(blk_run_queue_async); |
321 | |
322 | /** |
323 | * blk_run_queue - run a single device queue |
324 | * @q: The queue to run |
325 | * |
326 | * Description: |
327 | * Invoke request handling on this queue, if it has pending work to do. |
328 | * May be used to restart queueing when a request has completed. |
329 | */ |
330 | void blk_run_queue(struct request_queue *q) |
331 | { |
332 | unsigned long flags; |
333 | |
334 | spin_lock_irqsave(q->queue_lock, flags); |
335 | __blk_run_queue(q); |
336 | spin_unlock_irqrestore(q->queue_lock, flags); |
337 | } |
338 | EXPORT_SYMBOL(blk_run_queue); |
339 | |
340 | void blk_put_queue(struct request_queue *q) |
341 | { |
342 | kobject_put(&q->kobj); |
343 | } |
344 | EXPORT_SYMBOL(blk_put_queue); |
345 | |
346 | /** |
347 | * __blk_drain_queue - drain requests from request_queue |
348 | * @q: queue to drain |
349 | * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV |
350 | * |
351 | * Drain requests from @q. If @drain_all is set, all requests are drained. |
352 | * If not, only ELVPRIV requests are drained. The caller is responsible |
353 | * for ensuring that no new requests which need to be drained are queued. |
354 | */ |
355 | static void __blk_drain_queue(struct request_queue *q, bool drain_all) |
356 | __releases(q->queue_lock) |
357 | __acquires(q->queue_lock) |
358 | { |
359 | int i; |
360 | |
361 | lockdep_assert_held(q->queue_lock); |
362 | |
363 | while (true) { |
364 | bool drain = false; |
365 | |
366 | /* |
367 | * The caller might be trying to drain @q before its |
368 | * elevator is initialized. |
369 | */ |
370 | if (q->elevator) |
371 | elv_drain_elevator(q); |
372 | |
373 | blkcg_drain_queue(q); |
374 | |
375 | /* |
376 | * This function might be called on a queue which failed |
377 | * driver init after queue creation or is not yet fully |
378 | * active yet. Some drivers (e.g. fd and loop) get unhappy |
379 | * in such cases. Kick queue iff dispatch queue has |
380 | * something on it and @q has request_fn set. |
381 | */ |
382 | if (!list_empty(&q->queue_head) && q->request_fn) |
383 | __blk_run_queue(q); |
384 | |
385 | drain |= q->nr_rqs_elvpriv; |
386 | drain |= q->request_fn_active; |
387 | |
388 | /* |
389 | * Unfortunately, requests are queued at and tracked from |
390 | * multiple places and there's no single counter which can |
391 | * be drained. Check all the queues and counters. |
392 | */ |
393 | if (drain_all) { |
394 | drain |= !list_empty(&q->queue_head); |
395 | for (i = 0; i < 2; i++) { |
396 | drain |= q->nr_rqs[i]; |
397 | drain |= q->in_flight[i]; |
398 | drain |= !list_empty(&q->flush_queue[i]); |
399 | } |
400 | } |
401 | |
402 | if (!drain) |
403 | break; |
404 | |
405 | spin_unlock_irq(q->queue_lock); |
406 | |
407 | msleep(10); |
408 | |
409 | spin_lock_irq(q->queue_lock); |
410 | } |
411 | |
412 | /* |
413 | * With queue marked dead, any woken up waiter will fail the |
414 | * allocation path, so the wakeup chaining is lost and we're |
415 | * left with hung waiters. We need to wake up those waiters. |
416 | */ |
417 | if (q->request_fn) { |
418 | struct request_list *rl; |
419 | |
420 | blk_queue_for_each_rl(rl, q) |
421 | for (i = 0; i < ARRAY_SIZE(rl->wait); i++) |
422 | wake_up_all(&rl->wait[i]); |
423 | } |
424 | } |
425 | |
426 | /** |
427 | * blk_queue_bypass_start - enter queue bypass mode |
428 | * @q: queue of interest |
429 | * |
430 | * In bypass mode, only the dispatch FIFO queue of @q is used. This |
431 | * function makes @q enter bypass mode and drains all requests which were |
432 | * throttled or issued before. On return, it's guaranteed that no request |
433 | * is being throttled or has ELVPRIV set and blk_queue_bypass() %true |
434 | * inside queue or RCU read lock. |
435 | */ |
436 | void blk_queue_bypass_start(struct request_queue *q) |
437 | { |
438 | bool drain; |
439 | |
440 | spin_lock_irq(q->queue_lock); |
441 | drain = !q->bypass_depth++; |
442 | queue_flag_set(QUEUE_FLAG_BYPASS, q); |
443 | spin_unlock_irq(q->queue_lock); |
444 | |
445 | if (drain) { |
446 | spin_lock_irq(q->queue_lock); |
447 | __blk_drain_queue(q, false); |
448 | spin_unlock_irq(q->queue_lock); |
449 | |
450 | /* ensure blk_queue_bypass() is %true inside RCU read lock */ |
451 | synchronize_rcu(); |
452 | } |
453 | } |
454 | EXPORT_SYMBOL_GPL(blk_queue_bypass_start); |
455 | |
456 | /** |
457 | * blk_queue_bypass_end - leave queue bypass mode |
458 | * @q: queue of interest |
459 | * |
460 | * Leave bypass mode and restore the normal queueing behavior. |
461 | */ |
462 | void blk_queue_bypass_end(struct request_queue *q) |
463 | { |
464 | spin_lock_irq(q->queue_lock); |
465 | if (!--q->bypass_depth) |
466 | queue_flag_clear(QUEUE_FLAG_BYPASS, q); |
467 | WARN_ON_ONCE(q->bypass_depth < 0); |
468 | spin_unlock_irq(q->queue_lock); |
469 | } |
470 | EXPORT_SYMBOL_GPL(blk_queue_bypass_end); |
471 | |
472 | /** |
473 | * blk_cleanup_queue - shutdown a request queue |
474 | * @q: request queue to shutdown |
475 | * |
476 | * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and |
477 | * put it. All future requests will be failed immediately with -ENODEV. |
478 | */ |
479 | void blk_cleanup_queue(struct request_queue *q) |
480 | { |
481 | spinlock_t *lock = q->queue_lock; |
482 | |
483 | /* mark @q DYING, no new request or merges will be allowed afterwards */ |
484 | mutex_lock(&q->sysfs_lock); |
485 | queue_flag_set_unlocked(QUEUE_FLAG_DYING, q); |
486 | spin_lock_irq(lock); |
487 | |
488 | /* |
489 | * A dying queue is permanently in bypass mode till released. Note |
490 | * that, unlike blk_queue_bypass_start(), we aren't performing |
491 | * synchronize_rcu() after entering bypass mode to avoid the delay |
492 | * as some drivers create and destroy a lot of queues while |
493 | * probing. This is still safe because blk_release_queue() will be |
494 | * called only after the queue refcnt drops to zero and nothing, |
495 | * RCU or not, would be traversing the queue by then. |
496 | */ |
497 | q->bypass_depth++; |
498 | queue_flag_set(QUEUE_FLAG_BYPASS, q); |
499 | |
500 | queue_flag_set(QUEUE_FLAG_NOMERGES, q); |
501 | queue_flag_set(QUEUE_FLAG_NOXMERGES, q); |
502 | queue_flag_set(QUEUE_FLAG_DYING, q); |
503 | spin_unlock_irq(lock); |
504 | mutex_unlock(&q->sysfs_lock); |
505 | |
506 | /* |
507 | * Drain all requests queued before DYING marking. Set DEAD flag to |
508 | * prevent that q->request_fn() gets invoked after draining finished. |
509 | */ |
510 | if (q->mq_ops) { |
511 | blk_mq_drain_queue(q); |
512 | spin_lock_irq(lock); |
513 | } else { |
514 | spin_lock_irq(lock); |
515 | __blk_drain_queue(q, true); |
516 | } |
517 | queue_flag_set(QUEUE_FLAG_DEAD, q); |
518 | spin_unlock_irq(lock); |
519 | |
520 | /* @q won't process any more request, flush async actions */ |
521 | del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer); |
522 | blk_sync_queue(q); |
523 | |
524 | spin_lock_irq(lock); |
525 | if (q->queue_lock != &q->__queue_lock) |
526 | q->queue_lock = &q->__queue_lock; |
527 | spin_unlock_irq(lock); |
528 | |
529 | /* @q is and will stay empty, shutdown and put */ |
530 | blk_put_queue(q); |
531 | } |
532 | EXPORT_SYMBOL(blk_cleanup_queue); |
533 | |
534 | int blk_init_rl(struct request_list *rl, struct request_queue *q, |
535 | gfp_t gfp_mask) |
536 | { |
537 | if (unlikely(rl->rq_pool)) |
538 | return 0; |
539 | |
540 | rl->q = q; |
541 | rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0; |
542 | rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0; |
543 | init_waitqueue_head(&rl->wait[BLK_RW_SYNC]); |
544 | init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]); |
545 | |
546 | rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
547 | mempool_free_slab, request_cachep, |
548 | gfp_mask, q->node); |
549 | if (!rl->rq_pool) |
550 | return -ENOMEM; |
551 | |
552 | return 0; |
553 | } |
554 | |
555 | void blk_exit_rl(struct request_list *rl) |
556 | { |
557 | if (rl->rq_pool) |
558 | mempool_destroy(rl->rq_pool); |
559 | } |
560 | |
561 | struct request_queue *blk_alloc_queue(gfp_t gfp_mask) |
562 | { |
563 | return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE); |
564 | } |
565 | EXPORT_SYMBOL(blk_alloc_queue); |
566 | |
567 | struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) |
568 | { |
569 | struct request_queue *q; |
570 | int err; |
571 | |
572 | q = kmem_cache_alloc_node(blk_requestq_cachep, |
573 | gfp_mask | __GFP_ZERO, node_id); |
574 | if (!q) |
575 | return NULL; |
576 | |
577 | if (percpu_counter_init(&q->mq_usage_counter, 0)) |
578 | goto fail_q; |
579 | |
580 | q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask); |
581 | if (q->id < 0) |
582 | goto fail_c; |
583 | |
584 | q->backing_dev_info.ra_pages = |
585 | (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; |
586 | q->backing_dev_info.state = 0; |
587 | q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; |
588 | q->backing_dev_info.name = "block"; |
589 | q->node = node_id; |
590 | |
591 | err = bdi_init(&q->backing_dev_info); |
592 | if (err) |
593 | goto fail_id; |
594 | |
595 | setup_timer(&q->backing_dev_info.laptop_mode_wb_timer, |
596 | laptop_mode_timer_fn, (unsigned long) q); |
597 | setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q); |
598 | INIT_LIST_HEAD(&q->queue_head); |
599 | INIT_LIST_HEAD(&q->timeout_list); |
600 | INIT_LIST_HEAD(&q->icq_list); |
601 | #ifdef CONFIG_BLK_CGROUP |
602 | INIT_LIST_HEAD(&q->blkg_list); |
603 | #endif |
604 | INIT_LIST_HEAD(&q->flush_queue[0]); |
605 | INIT_LIST_HEAD(&q->flush_queue[1]); |
606 | INIT_LIST_HEAD(&q->flush_data_in_flight); |
607 | INIT_DELAYED_WORK(&q->delay_work, blk_delay_work); |
608 | |
609 | kobject_init(&q->kobj, &blk_queue_ktype); |
610 | |
611 | mutex_init(&q->sysfs_lock); |
612 | spin_lock_init(&q->__queue_lock); |
613 | |
614 | /* |
615 | * By default initialize queue_lock to internal lock and driver can |
616 | * override it later if need be. |
617 | */ |
618 | q->queue_lock = &q->__queue_lock; |
619 | |
620 | /* |
621 | * A queue starts its life with bypass turned on to avoid |
622 | * unnecessary bypass on/off overhead and nasty surprises during |
623 | * init. The initial bypass will be finished when the queue is |
624 | * registered by blk_register_queue(). |
625 | */ |
626 | q->bypass_depth = 1; |
627 | __set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags); |
628 | |
629 | init_waitqueue_head(&q->mq_freeze_wq); |
630 | |
631 | if (blkcg_init_queue(q)) |
632 | goto fail_bdi; |
633 | |
634 | return q; |
635 | |
636 | fail_bdi: |
637 | bdi_destroy(&q->backing_dev_info); |
638 | fail_id: |
639 | ida_simple_remove(&blk_queue_ida, q->id); |
640 | fail_c: |
641 | percpu_counter_destroy(&q->mq_usage_counter); |
642 | fail_q: |
643 | kmem_cache_free(blk_requestq_cachep, q); |
644 | return NULL; |
645 | } |
646 | EXPORT_SYMBOL(blk_alloc_queue_node); |
647 | |
648 | /** |
649 | * blk_init_queue - prepare a request queue for use with a block device |
650 | * @rfn: The function to be called to process requests that have been |
651 | * placed on the queue. |
652 | * @lock: Request queue spin lock |
653 | * |
654 | * Description: |
655 | * If a block device wishes to use the standard request handling procedures, |
656 | * which sorts requests and coalesces adjacent requests, then it must |
657 | * call blk_init_queue(). The function @rfn will be called when there |
658 | * are requests on the queue that need to be processed. If the device |
659 | * supports plugging, then @rfn may not be called immediately when requests |
660 | * are available on the queue, but may be called at some time later instead. |
661 | * Plugged queues are generally unplugged when a buffer belonging to one |
662 | * of the requests on the queue is needed, or due to memory pressure. |
663 | * |
664 | * @rfn is not required, or even expected, to remove all requests off the |
665 | * queue, but only as many as it can handle at a time. If it does leave |
666 | * requests on the queue, it is responsible for arranging that the requests |
667 | * get dealt with eventually. |
668 | * |
669 | * The queue spin lock must be held while manipulating the requests on the |
670 | * request queue; this lock will be taken also from interrupt context, so irq |
671 | * disabling is needed for it. |
672 | * |
673 | * Function returns a pointer to the initialized request queue, or %NULL if |
674 | * it didn't succeed. |
675 | * |
676 | * Note: |
677 | * blk_init_queue() must be paired with a blk_cleanup_queue() call |
678 | * when the block device is deactivated (such as at module unload). |
679 | **/ |
680 | |
681 | struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) |
682 | { |
683 | return blk_init_queue_node(rfn, lock, NUMA_NO_NODE); |
684 | } |
685 | EXPORT_SYMBOL(blk_init_queue); |
686 | |
687 | struct request_queue * |
688 | blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) |
689 | { |
690 | struct request_queue *uninit_q, *q; |
691 | |
692 | uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id); |
693 | if (!uninit_q) |
694 | return NULL; |
695 | |
696 | q = blk_init_allocated_queue(uninit_q, rfn, lock); |
697 | if (!q) |
698 | blk_cleanup_queue(uninit_q); |
699 | |
700 | return q; |
701 | } |
702 | EXPORT_SYMBOL(blk_init_queue_node); |
703 | |
704 | struct request_queue * |
705 | blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn, |
706 | spinlock_t *lock) |
707 | { |
708 | if (!q) |
709 | return NULL; |
710 | |
711 | q->flush_rq = kzalloc(sizeof(struct request), GFP_KERNEL); |
712 | if (!q->flush_rq) |
713 | return NULL; |
714 | |
715 | if (blk_init_rl(&q->root_rl, q, GFP_KERNEL)) |
716 | goto fail; |
717 | |
718 | q->request_fn = rfn; |
719 | q->prep_rq_fn = NULL; |
720 | q->unprep_rq_fn = NULL; |
721 | q->queue_flags |= QUEUE_FLAG_DEFAULT; |
722 | |
723 | /* Override internal queue lock with supplied lock pointer */ |
724 | if (lock) |
725 | q->queue_lock = lock; |
726 | |
727 | /* |
728 | * This also sets hw/phys segments, boundary and size |
729 | */ |
730 | blk_queue_make_request(q, blk_queue_bio); |
731 | |
732 | q->sg_reserved_size = INT_MAX; |
733 | |
734 | /* Protect q->elevator from elevator_change */ |
735 | mutex_lock(&q->sysfs_lock); |
736 | |
737 | /* init elevator */ |
738 | if (elevator_init(q, NULL)) { |
739 | mutex_unlock(&q->sysfs_lock); |
740 | goto fail; |
741 | } |
742 | |
743 | mutex_unlock(&q->sysfs_lock); |
744 | |
745 | return q; |
746 | |
747 | fail: |
748 | kfree(q->flush_rq); |
749 | return NULL; |
750 | } |
751 | EXPORT_SYMBOL(blk_init_allocated_queue); |
752 | |
753 | bool blk_get_queue(struct request_queue *q) |
754 | { |
755 | if (likely(!blk_queue_dying(q))) { |
756 | __blk_get_queue(q); |
757 | return true; |
758 | } |
759 | |
760 | return false; |
761 | } |
762 | EXPORT_SYMBOL(blk_get_queue); |
763 | |
764 | static inline void blk_free_request(struct request_list *rl, struct request *rq) |
765 | { |
766 | if (rq->cmd_flags & REQ_ELVPRIV) { |
767 | elv_put_request(rl->q, rq); |
768 | if (rq->elv.icq) |
769 | put_io_context(rq->elv.icq->ioc); |
770 | } |
771 | |
772 | mempool_free(rq, rl->rq_pool); |
773 | } |
774 | |
775 | /* |
776 | * ioc_batching returns true if the ioc is a valid batching request and |
777 | * should be given priority access to a request. |
778 | */ |
779 | static inline int ioc_batching(struct request_queue *q, struct io_context *ioc) |
780 | { |
781 | if (!ioc) |
782 | return 0; |
783 | |
784 | /* |
785 | * Make sure the process is able to allocate at least 1 request |
786 | * even if the batch times out, otherwise we could theoretically |
787 | * lose wakeups. |
788 | */ |
789 | return ioc->nr_batch_requests == q->nr_batching || |
790 | (ioc->nr_batch_requests > 0 |
791 | && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); |
792 | } |
793 | |
794 | /* |
795 | * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This |
796 | * will cause the process to be a "batcher" on all queues in the system. This |
797 | * is the behaviour we want though - once it gets a wakeup it should be given |
798 | * a nice run. |
799 | */ |
800 | static void ioc_set_batching(struct request_queue *q, struct io_context *ioc) |
801 | { |
802 | if (!ioc || ioc_batching(q, ioc)) |
803 | return; |
804 | |
805 | ioc->nr_batch_requests = q->nr_batching; |
806 | ioc->last_waited = jiffies; |
807 | } |
808 | |
809 | static void __freed_request(struct request_list *rl, int sync) |
810 | { |
811 | struct request_queue *q = rl->q; |
812 | |
813 | /* |
814 | * bdi isn't aware of blkcg yet. As all async IOs end up root |
815 | * blkcg anyway, just use root blkcg state. |
816 | */ |
817 | if (rl == &q->root_rl && |
818 | rl->count[sync] < queue_congestion_off_threshold(q)) |
819 | blk_clear_queue_congested(q, sync); |
820 | |
821 | if (rl->count[sync] + 1 <= q->nr_requests) { |
822 | if (waitqueue_active(&rl->wait[sync])) |
823 | wake_up(&rl->wait[sync]); |
824 | |
825 | blk_clear_rl_full(rl, sync); |
826 | } |
827 | } |
828 | |
829 | /* |
830 | * A request has just been released. Account for it, update the full and |
831 | * congestion status, wake up any waiters. Called under q->queue_lock. |
832 | */ |
833 | static void freed_request(struct request_list *rl, unsigned int flags) |
834 | { |
835 | struct request_queue *q = rl->q; |
836 | int sync = rw_is_sync(flags); |
837 | |
838 | q->nr_rqs[sync]--; |
839 | rl->count[sync]--; |
840 | if (flags & REQ_ELVPRIV) |
841 | q->nr_rqs_elvpriv--; |
842 | |
843 | __freed_request(rl, sync); |
844 | |
845 | if (unlikely(rl->starved[sync ^ 1])) |
846 | __freed_request(rl, sync ^ 1); |
847 | } |
848 | |
849 | /* |
850 | * Determine if elevator data should be initialized when allocating the |
851 | * request associated with @bio. |
852 | */ |
853 | static bool blk_rq_should_init_elevator(struct bio *bio) |
854 | { |
855 | if (!bio) |
856 | return true; |
857 | |
858 | /* |
859 | * Flush requests do not use the elevator so skip initialization. |
860 | * This allows a request to share the flush and elevator data. |
861 | */ |
862 | if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) |
863 | return false; |
864 | |
865 | return true; |
866 | } |
867 | |
868 | /** |
869 | * rq_ioc - determine io_context for request allocation |
870 | * @bio: request being allocated is for this bio (can be %NULL) |
871 | * |
872 | * Determine io_context to use for request allocation for @bio. May return |
873 | * %NULL if %current->io_context doesn't exist. |
874 | */ |
875 | static struct io_context *rq_ioc(struct bio *bio) |
876 | { |
877 | #ifdef CONFIG_BLK_CGROUP |
878 | if (bio && bio->bi_ioc) |
879 | return bio->bi_ioc; |
880 | #endif |
881 | return current->io_context; |
882 | } |
883 | |
884 | /** |
885 | * __get_request - get a free request |
886 | * @rl: request list to allocate from |
887 | * @rw_flags: RW and SYNC flags |
888 | * @bio: bio to allocate request for (can be %NULL) |
889 | * @gfp_mask: allocation mask |
890 | * |
891 | * Get a free request from @q. This function may fail under memory |
892 | * pressure or if @q is dead. |
893 | * |
894 | * Must be callled with @q->queue_lock held and, |
895 | * Returns %NULL on failure, with @q->queue_lock held. |
896 | * Returns !%NULL on success, with @q->queue_lock *not held*. |
897 | */ |
898 | static struct request *__get_request(struct request_list *rl, int rw_flags, |
899 | struct bio *bio, gfp_t gfp_mask) |
900 | { |
901 | struct request_queue *q = rl->q; |
902 | struct request *rq; |
903 | struct elevator_type *et = q->elevator->type; |
904 | struct io_context *ioc = rq_ioc(bio); |
905 | struct io_cq *icq = NULL; |
906 | const bool is_sync = rw_is_sync(rw_flags) != 0; |
907 | int may_queue; |
908 | |
909 | if (unlikely(blk_queue_dying(q))) |
910 | return NULL; |
911 | |
912 | may_queue = elv_may_queue(q, rw_flags); |
913 | if (may_queue == ELV_MQUEUE_NO) |
914 | goto rq_starved; |
915 | |
916 | if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) { |
917 | if (rl->count[is_sync]+1 >= q->nr_requests) { |
918 | /* |
919 | * The queue will fill after this allocation, so set |
920 | * it as full, and mark this process as "batching". |
921 | * This process will be allowed to complete a batch of |
922 | * requests, others will be blocked. |
923 | */ |
924 | if (!blk_rl_full(rl, is_sync)) { |
925 | ioc_set_batching(q, ioc); |
926 | blk_set_rl_full(rl, is_sync); |
927 | } else { |
928 | if (may_queue != ELV_MQUEUE_MUST |
929 | && !ioc_batching(q, ioc)) { |
930 | /* |
931 | * The queue is full and the allocating |
932 | * process is not a "batcher", and not |
933 | * exempted by the IO scheduler |
934 | */ |
935 | return NULL; |
936 | } |
937 | } |
938 | } |
939 | /* |
940 | * bdi isn't aware of blkcg yet. As all async IOs end up |
941 | * root blkcg anyway, just use root blkcg state. |
942 | */ |
943 | if (rl == &q->root_rl) |
944 | blk_set_queue_congested(q, is_sync); |
945 | } |
946 | |
947 | /* |
948 | * Only allow batching queuers to allocate up to 50% over the defined |
949 | * limit of requests, otherwise we could have thousands of requests |
950 | * allocated with any setting of ->nr_requests |
951 | */ |
952 | if (rl->count[is_sync] >= (3 * q->nr_requests / 2)) |
953 | return NULL; |
954 | |
955 | q->nr_rqs[is_sync]++; |
956 | rl->count[is_sync]++; |
957 | rl->starved[is_sync] = 0; |
958 | |
959 | /* |
960 | * Decide whether the new request will be managed by elevator. If |
961 | * so, mark @rw_flags and increment elvpriv. Non-zero elvpriv will |
962 | * prevent the current elevator from being destroyed until the new |
963 | * request is freed. This guarantees icq's won't be destroyed and |
964 | * makes creating new ones safe. |
965 | * |
966 | * Also, lookup icq while holding queue_lock. If it doesn't exist, |
967 | * it will be created after releasing queue_lock. |
968 | */ |
969 | if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) { |
970 | rw_flags |= REQ_ELVPRIV; |
971 | q->nr_rqs_elvpriv++; |
972 | if (et->icq_cache && ioc) |
973 | icq = ioc_lookup_icq(ioc, q); |
974 | } |
975 | |
976 | if (blk_queue_io_stat(q)) |
977 | rw_flags |= REQ_IO_STAT; |
978 | spin_unlock_irq(q->queue_lock); |
979 | |
980 | /* allocate and init request */ |
981 | rq = mempool_alloc(rl->rq_pool, gfp_mask); |
982 | if (!rq) |
983 | goto fail_alloc; |
984 | |
985 | blk_rq_init(q, rq); |
986 | blk_rq_set_rl(rq, rl); |
987 | rq->cmd_flags = rw_flags | REQ_ALLOCED; |
988 | |
989 | /* init elvpriv */ |
990 | if (rw_flags & REQ_ELVPRIV) { |
991 | if (unlikely(et->icq_cache && !icq)) { |
992 | if (ioc) |
993 | icq = ioc_create_icq(ioc, q, gfp_mask); |
994 | if (!icq) |
995 | goto fail_elvpriv; |
996 | } |
997 | |
998 | rq->elv.icq = icq; |
999 | if (unlikely(elv_set_request(q, rq, bio, gfp_mask))) |
1000 | goto fail_elvpriv; |
1001 | |
1002 | /* @rq->elv.icq holds io_context until @rq is freed */ |
1003 | if (icq) |
1004 | get_io_context(icq->ioc); |
1005 | } |
1006 | out: |
1007 | /* |
1008 | * ioc may be NULL here, and ioc_batching will be false. That's |
1009 | * OK, if the queue is under the request limit then requests need |
1010 | * not count toward the nr_batch_requests limit. There will always |
1011 | * be some limit enforced by BLK_BATCH_TIME. |
1012 | */ |
1013 | if (ioc_batching(q, ioc)) |
1014 | ioc->nr_batch_requests--; |
1015 | |
1016 | trace_block_getrq(q, bio, rw_flags & 1); |
1017 | return rq; |
1018 | |
1019 | fail_elvpriv: |
1020 | /* |
1021 | * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed |
1022 | * and may fail indefinitely under memory pressure and thus |
1023 | * shouldn't stall IO. Treat this request as !elvpriv. This will |
1024 | * disturb iosched and blkcg but weird is bettern than dead. |
1025 | */ |
1026 | printk_ratelimited(KERN_WARNING "%s: request aux data allocation failed, iosched may be disturbed\n", |
1027 | dev_name(q->backing_dev_info.dev)); |
1028 | |
1029 | rq->cmd_flags &= ~REQ_ELVPRIV; |
1030 | rq->elv.icq = NULL; |
1031 | |
1032 | spin_lock_irq(q->queue_lock); |
1033 | q->nr_rqs_elvpriv--; |
1034 | spin_unlock_irq(q->queue_lock); |
1035 | goto out; |
1036 | |
1037 | fail_alloc: |
1038 | /* |
1039 | * Allocation failed presumably due to memory. Undo anything we |
1040 | * might have messed up. |
1041 | * |
1042 | * Allocating task should really be put onto the front of the wait |
1043 | * queue, but this is pretty rare. |
1044 | */ |
1045 | spin_lock_irq(q->queue_lock); |
1046 | freed_request(rl, rw_flags); |
1047 | |
1048 | /* |
1049 | * in the very unlikely event that allocation failed and no |
1050 | * requests for this direction was pending, mark us starved so that |
1051 | * freeing of a request in the other direction will notice |
1052 | * us. another possible fix would be to split the rq mempool into |
1053 | * READ and WRITE |
1054 | */ |
1055 | rq_starved: |
1056 | if (unlikely(rl->count[is_sync] == 0)) |
1057 | rl->starved[is_sync] = 1; |
1058 | return NULL; |
1059 | } |
1060 | |
1061 | /** |
1062 | * get_request - get a free request |
1063 | * @q: request_queue to allocate request from |
1064 | * @rw_flags: RW and SYNC flags |
1065 | * @bio: bio to allocate request for (can be %NULL) |
1066 | * @gfp_mask: allocation mask |
1067 | * |
1068 | * Get a free request from @q. If %__GFP_WAIT is set in @gfp_mask, this |
1069 | * function keeps retrying under memory pressure and fails iff @q is dead. |
1070 | * |
1071 | * Must be callled with @q->queue_lock held and, |
1072 | * Returns %NULL on failure, with @q->queue_lock held. |
1073 | * Returns !%NULL on success, with @q->queue_lock *not held*. |
1074 | */ |
1075 | static struct request *get_request(struct request_queue *q, int rw_flags, |
1076 | struct bio *bio, gfp_t gfp_mask) |
1077 | { |
1078 | const bool is_sync = rw_is_sync(rw_flags) != 0; |
1079 | DEFINE_WAIT(wait); |
1080 | struct request_list *rl; |
1081 | struct request *rq; |
1082 | |
1083 | rl = blk_get_rl(q, bio); /* transferred to @rq on success */ |
1084 | retry: |
1085 | rq = __get_request(rl, rw_flags, bio, gfp_mask); |
1086 | if (rq) |
1087 | return rq; |
1088 | |
1089 | if (!(gfp_mask & __GFP_WAIT) || unlikely(blk_queue_dying(q))) { |
1090 | blk_put_rl(rl); |
1091 | return NULL; |
1092 | } |
1093 | |
1094 | /* wait on @rl and retry */ |
1095 | prepare_to_wait_exclusive(&rl->wait[is_sync], &wait, |
1096 | TASK_UNINTERRUPTIBLE); |
1097 | |
1098 | trace_block_sleeprq(q, bio, rw_flags & 1); |
1099 | |
1100 | spin_unlock_irq(q->queue_lock); |
1101 | io_schedule(); |
1102 | |
1103 | /* |
1104 | * After sleeping, we become a "batching" process and will be able |
1105 | * to allocate at least one request, and up to a big batch of them |
1106 | * for a small period time. See ioc_batching, ioc_set_batching |
1107 | */ |
1108 | ioc_set_batching(q, current->io_context); |
1109 | |
1110 | spin_lock_irq(q->queue_lock); |
1111 | finish_wait(&rl->wait[is_sync], &wait); |
1112 | |
1113 | goto retry; |
1114 | } |
1115 | |
1116 | static struct request *blk_old_get_request(struct request_queue *q, int rw, |
1117 | gfp_t gfp_mask) |
1118 | { |
1119 | struct request *rq; |
1120 | |
1121 | BUG_ON(rw != READ && rw != WRITE); |
1122 | |
1123 | /* create ioc upfront */ |
1124 | create_io_context(gfp_mask, q->node); |
1125 | |
1126 | spin_lock_irq(q->queue_lock); |
1127 | rq = get_request(q, rw, NULL, gfp_mask); |
1128 | if (!rq) |
1129 | spin_unlock_irq(q->queue_lock); |
1130 | /* q->queue_lock is unlocked at this point */ |
1131 | |
1132 | return rq; |
1133 | } |
1134 | |
1135 | struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask) |
1136 | { |
1137 | if (q->mq_ops) |
1138 | return blk_mq_alloc_request(q, rw, gfp_mask); |
1139 | else |
1140 | return blk_old_get_request(q, rw, gfp_mask); |
1141 | } |
1142 | EXPORT_SYMBOL(blk_get_request); |
1143 | |
1144 | /** |
1145 | * blk_make_request - given a bio, allocate a corresponding struct request. |
1146 | * @q: target request queue |
1147 | * @bio: The bio describing the memory mappings that will be submitted for IO. |
1148 | * It may be a chained-bio properly constructed by block/bio layer. |
1149 | * @gfp_mask: gfp flags to be used for memory allocation |
1150 | * |
1151 | * blk_make_request is the parallel of generic_make_request for BLOCK_PC |
1152 | * type commands. Where the struct request needs to be farther initialized by |
1153 | * the caller. It is passed a &struct bio, which describes the memory info of |
1154 | * the I/O transfer. |
1155 | * |
1156 | * The caller of blk_make_request must make sure that bi_io_vec |
1157 | * are set to describe the memory buffers. That bio_data_dir() will return |
1158 | * the needed direction of the request. (And all bio's in the passed bio-chain |
1159 | * are properly set accordingly) |
1160 | * |
1161 | * If called under none-sleepable conditions, mapped bio buffers must not |
1162 | * need bouncing, by calling the appropriate masked or flagged allocator, |
1163 | * suitable for the target device. Otherwise the call to blk_queue_bounce will |
1164 | * BUG. |
1165 | * |
1166 | * WARNING: When allocating/cloning a bio-chain, careful consideration should be |
1167 | * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for |
1168 | * anything but the first bio in the chain. Otherwise you risk waiting for IO |
1169 | * completion of a bio that hasn't been submitted yet, thus resulting in a |
1170 | * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead |
1171 | * of bio_alloc(), as that avoids the mempool deadlock. |
1172 | * If possible a big IO should be split into smaller parts when allocation |
1173 | * fails. Partial allocation should not be an error, or you risk a live-lock. |
1174 | */ |
1175 | struct request *blk_make_request(struct request_queue *q, struct bio *bio, |
1176 | gfp_t gfp_mask) |
1177 | { |
1178 | struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask); |
1179 | |
1180 | if (unlikely(!rq)) |
1181 | return ERR_PTR(-ENOMEM); |
1182 | |
1183 | for_each_bio(bio) { |
1184 | struct bio *bounce_bio = bio; |
1185 | int ret; |
1186 | |
1187 | blk_queue_bounce(q, &bounce_bio); |
1188 | ret = blk_rq_append_bio(q, rq, bounce_bio); |
1189 | if (unlikely(ret)) { |
1190 | blk_put_request(rq); |
1191 | return ERR_PTR(ret); |
1192 | } |
1193 | } |
1194 | |
1195 | return rq; |
1196 | } |
1197 | EXPORT_SYMBOL(blk_make_request); |
1198 | |
1199 | /** |
1200 | * blk_requeue_request - put a request back on queue |
1201 | * @q: request queue where request should be inserted |
1202 | * @rq: request to be inserted |
1203 | * |
1204 | * Description: |
1205 | * Drivers often keep queueing requests until the hardware cannot accept |
1206 | * more, when that condition happens we need to put the request back |
1207 | * on the queue. Must be called with queue lock held. |
1208 | */ |
1209 | void blk_requeue_request(struct request_queue *q, struct request *rq) |
1210 | { |
1211 | blk_delete_timer(rq); |
1212 | blk_clear_rq_complete(rq); |
1213 | trace_block_rq_requeue(q, rq); |
1214 | |
1215 | if (blk_rq_tagged(rq)) |
1216 | blk_queue_end_tag(q, rq); |
1217 | |
1218 | BUG_ON(blk_queued_rq(rq)); |
1219 | |
1220 | elv_requeue_request(q, rq); |
1221 | } |
1222 | EXPORT_SYMBOL(blk_requeue_request); |
1223 | |
1224 | static void add_acct_request(struct request_queue *q, struct request *rq, |
1225 | int where) |
1226 | { |
1227 | blk_account_io_start(rq, true); |
1228 | __elv_add_request(q, rq, where); |
1229 | } |
1230 | |
1231 | static void part_round_stats_single(int cpu, struct hd_struct *part, |
1232 | unsigned long now) |
1233 | { |
1234 | if (now == part->stamp) |
1235 | return; |
1236 | |
1237 | if (part_in_flight(part)) { |
1238 | __part_stat_add(cpu, part, time_in_queue, |
1239 | part_in_flight(part) * (now - part->stamp)); |
1240 | __part_stat_add(cpu, part, io_ticks, (now - part->stamp)); |
1241 | } |
1242 | part->stamp = now; |
1243 | } |
1244 | |
1245 | /** |
1246 | * part_round_stats() - Round off the performance stats on a struct disk_stats. |
1247 | * @cpu: cpu number for stats access |
1248 | * @part: target partition |
1249 | * |
1250 | * The average IO queue length and utilisation statistics are maintained |
1251 | * by observing the current state of the queue length and the amount of |
1252 | * time it has been in this state for. |
1253 | * |
1254 | * Normally, that accounting is done on IO completion, but that can result |
1255 | * in more than a second's worth of IO being accounted for within any one |
1256 | * second, leading to >100% utilisation. To deal with that, we call this |
1257 | * function to do a round-off before returning the results when reading |
1258 | * /proc/diskstats. This accounts immediately for all queue usage up to |
1259 | * the current jiffies and restarts the counters again. |
1260 | */ |
1261 | void part_round_stats(int cpu, struct hd_struct *part) |
1262 | { |
1263 | unsigned long now = jiffies; |
1264 | |
1265 | if (part->partno) |
1266 | part_round_stats_single(cpu, &part_to_disk(part)->part0, now); |
1267 | part_round_stats_single(cpu, part, now); |
1268 | } |
1269 | EXPORT_SYMBOL_GPL(part_round_stats); |
1270 | |
1271 | #ifdef CONFIG_PM_RUNTIME |
1272 | static void blk_pm_put_request(struct request *rq) |
1273 | { |
1274 | if (rq->q->dev && !(rq->cmd_flags & REQ_PM) && !--rq->q->nr_pending) |
1275 | pm_runtime_mark_last_busy(rq->q->dev); |
1276 | } |
1277 | #else |
1278 | static inline void blk_pm_put_request(struct request *rq) {} |
1279 | #endif |
1280 | |
1281 | /* |
1282 | * queue lock must be held |
1283 | */ |
1284 | void __blk_put_request(struct request_queue *q, struct request *req) |
1285 | { |
1286 | if (unlikely(!q)) |
1287 | return; |
1288 | |
1289 | if (q->mq_ops) { |
1290 | blk_mq_free_request(req); |
1291 | return; |
1292 | } |
1293 | |
1294 | blk_pm_put_request(req); |
1295 | |
1296 | elv_completed_request(q, req); |
1297 | |
1298 | /* this is a bio leak */ |
1299 | WARN_ON(req->bio != NULL); |
1300 | |
1301 | /* |
1302 | * Request may not have originated from ll_rw_blk. if not, |
1303 | * it didn't come out of our reserved rq pools |
1304 | */ |
1305 | if (req->cmd_flags & REQ_ALLOCED) { |
1306 | unsigned int flags = req->cmd_flags; |
1307 | struct request_list *rl = blk_rq_rl(req); |
1308 | |
1309 | BUG_ON(!list_empty(&req->queuelist)); |
1310 | BUG_ON(ELV_ON_HASH(req)); |
1311 | |
1312 | blk_free_request(rl, req); |
1313 | freed_request(rl, flags); |
1314 | blk_put_rl(rl); |
1315 | } |
1316 | } |
1317 | EXPORT_SYMBOL_GPL(__blk_put_request); |
1318 | |
1319 | void blk_put_request(struct request *req) |
1320 | { |
1321 | struct request_queue *q = req->q; |
1322 | |
1323 | if (q->mq_ops) |
1324 | blk_mq_free_request(req); |
1325 | else { |
1326 | unsigned long flags; |
1327 | |
1328 | spin_lock_irqsave(q->queue_lock, flags); |
1329 | __blk_put_request(q, req); |
1330 | spin_unlock_irqrestore(q->queue_lock, flags); |
1331 | } |
1332 | } |
1333 | EXPORT_SYMBOL(blk_put_request); |
1334 | |
1335 | /** |
1336 | * blk_add_request_payload - add a payload to a request |
1337 | * @rq: request to update |
1338 | * @page: page backing the payload |
1339 | * @len: length of the payload. |
1340 | * |
1341 | * This allows to later add a payload to an already submitted request by |
1342 | * a block driver. The driver needs to take care of freeing the payload |
1343 | * itself. |
1344 | * |
1345 | * Note that this is a quite horrible hack and nothing but handling of |
1346 | * discard requests should ever use it. |
1347 | */ |
1348 | void blk_add_request_payload(struct request *rq, struct page *page, |
1349 | unsigned int len) |
1350 | { |
1351 | struct bio *bio = rq->bio; |
1352 | |
1353 | bio->bi_io_vec->bv_page = page; |
1354 | bio->bi_io_vec->bv_offset = 0; |
1355 | bio->bi_io_vec->bv_len = len; |
1356 | |
1357 | bio->bi_iter.bi_size = len; |
1358 | bio->bi_vcnt = 1; |
1359 | bio->bi_phys_segments = 1; |
1360 | |
1361 | rq->__data_len = rq->resid_len = len; |
1362 | rq->nr_phys_segments = 1; |
1363 | rq->buffer = bio_data(bio); |
1364 | } |
1365 | EXPORT_SYMBOL_GPL(blk_add_request_payload); |
1366 | |
1367 | bool bio_attempt_back_merge(struct request_queue *q, struct request *req, |
1368 | struct bio *bio) |
1369 | { |
1370 | const int ff = bio->bi_rw & REQ_FAILFAST_MASK; |
1371 | |
1372 | if (!ll_back_merge_fn(q, req, bio)) |
1373 | return false; |
1374 | |
1375 | trace_block_bio_backmerge(q, req, bio); |
1376 | |
1377 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) |
1378 | blk_rq_set_mixed_merge(req); |
1379 | |
1380 | req->biotail->bi_next = bio; |
1381 | req->biotail = bio; |
1382 | req->__data_len += bio->bi_iter.bi_size; |
1383 | req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); |
1384 | |
1385 | blk_account_io_start(req, false); |
1386 | return true; |
1387 | } |
1388 | |
1389 | bool bio_attempt_front_merge(struct request_queue *q, struct request *req, |
1390 | struct bio *bio) |
1391 | { |
1392 | const int ff = bio->bi_rw & REQ_FAILFAST_MASK; |
1393 | |
1394 | if (!ll_front_merge_fn(q, req, bio)) |
1395 | return false; |
1396 | |
1397 | trace_block_bio_frontmerge(q, req, bio); |
1398 | |
1399 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) |
1400 | blk_rq_set_mixed_merge(req); |
1401 | |
1402 | bio->bi_next = req->bio; |
1403 | req->bio = bio; |
1404 | |
1405 | /* |
1406 | * may not be valid. if the low level driver said |
1407 | * it didn't need a bounce buffer then it better |
1408 | * not touch req->buffer either... |
1409 | */ |
1410 | req->buffer = bio_data(bio); |
1411 | req->__sector = bio->bi_iter.bi_sector; |
1412 | req->__data_len += bio->bi_iter.bi_size; |
1413 | req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); |
1414 | |
1415 | blk_account_io_start(req, false); |
1416 | return true; |
1417 | } |
1418 | |
1419 | /** |
1420 | * blk_attempt_plug_merge - try to merge with %current's plugged list |
1421 | * @q: request_queue new bio is being queued at |
1422 | * @bio: new bio being queued |
1423 | * @request_count: out parameter for number of traversed plugged requests |
1424 | * |
1425 | * Determine whether @bio being queued on @q can be merged with a request |
1426 | * on %current's plugged list. Returns %true if merge was successful, |
1427 | * otherwise %false. |
1428 | * |
1429 | * Plugging coalesces IOs from the same issuer for the same purpose without |
1430 | * going through @q->queue_lock. As such it's more of an issuing mechanism |
1431 | * than scheduling, and the request, while may have elvpriv data, is not |
1432 | * added on the elevator at this point. In addition, we don't have |
1433 | * reliable access to the elevator outside queue lock. Only check basic |
1434 | * merging parameters without querying the elevator. |
1435 | */ |
1436 | bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, |
1437 | unsigned int *request_count) |
1438 | { |
1439 | struct blk_plug *plug; |
1440 | struct request *rq; |
1441 | bool ret = false; |
1442 | struct list_head *plug_list; |
1443 | |
1444 | if (blk_queue_nomerges(q)) |
1445 | goto out; |
1446 | |
1447 | plug = current->plug; |
1448 | if (!plug) |
1449 | goto out; |
1450 | *request_count = 0; |
1451 | |
1452 | if (q->mq_ops) |
1453 | plug_list = &plug->mq_list; |
1454 | else |
1455 | plug_list = &plug->list; |
1456 | |
1457 | list_for_each_entry_reverse(rq, plug_list, queuelist) { |
1458 | int el_ret; |
1459 | |
1460 | if (rq->q == q) |
1461 | (*request_count)++; |
1462 | |
1463 | if (rq->q != q || !blk_rq_merge_ok(rq, bio)) |
1464 | continue; |
1465 | |
1466 | el_ret = blk_try_merge(rq, bio); |
1467 | if (el_ret == ELEVATOR_BACK_MERGE) { |
1468 | ret = bio_attempt_back_merge(q, rq, bio); |
1469 | if (ret) |
1470 | break; |
1471 | } else if (el_ret == ELEVATOR_FRONT_MERGE) { |
1472 | ret = bio_attempt_front_merge(q, rq, bio); |
1473 | if (ret) |
1474 | break; |
1475 | } |
1476 | } |
1477 | out: |
1478 | return ret; |
1479 | } |
1480 | |
1481 | void init_request_from_bio(struct request *req, struct bio *bio) |
1482 | { |
1483 | req->cmd_type = REQ_TYPE_FS; |
1484 | |
1485 | req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK; |
1486 | if (bio->bi_rw & REQ_RAHEAD) |
1487 | req->cmd_flags |= REQ_FAILFAST_MASK; |
1488 | |
1489 | req->errors = 0; |
1490 | req->__sector = bio->bi_iter.bi_sector; |
1491 | req->ioprio = bio_prio(bio); |
1492 | blk_rq_bio_prep(req->q, req, bio); |
1493 | } |
1494 | |
1495 | void blk_queue_bio(struct request_queue *q, struct bio *bio) |
1496 | { |
1497 | const bool sync = !!(bio->bi_rw & REQ_SYNC); |
1498 | struct blk_plug *plug; |
1499 | int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT; |
1500 | struct request *req; |
1501 | unsigned int request_count = 0; |
1502 | |
1503 | /* |
1504 | * low level driver can indicate that it wants pages above a |
1505 | * certain limit bounced to low memory (ie for highmem, or even |
1506 | * ISA dma in theory) |
1507 | */ |
1508 | blk_queue_bounce(q, &bio); |
1509 | |
1510 | if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) { |
1511 | bio_endio(bio, -EIO); |
1512 | return; |
1513 | } |
1514 | |
1515 | if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) { |
1516 | spin_lock_irq(q->queue_lock); |
1517 | where = ELEVATOR_INSERT_FLUSH; |
1518 | goto get_rq; |
1519 | } |
1520 | |
1521 | /* |
1522 | * Check if we can merge with the plugged list before grabbing |
1523 | * any locks. |
1524 | */ |
1525 | if (blk_attempt_plug_merge(q, bio, &request_count)) |
1526 | return; |
1527 | |
1528 | spin_lock_irq(q->queue_lock); |
1529 | |
1530 | el_ret = elv_merge(q, &req, bio); |
1531 | if (el_ret == ELEVATOR_BACK_MERGE) { |
1532 | if (bio_attempt_back_merge(q, req, bio)) { |
1533 | elv_bio_merged(q, req, bio); |
1534 | if (!attempt_back_merge(q, req)) |
1535 | elv_merged_request(q, req, el_ret); |
1536 | goto out_unlock; |
1537 | } |
1538 | } else if (el_ret == ELEVATOR_FRONT_MERGE) { |
1539 | if (bio_attempt_front_merge(q, req, bio)) { |
1540 | elv_bio_merged(q, req, bio); |
1541 | if (!attempt_front_merge(q, req)) |
1542 | elv_merged_request(q, req, el_ret); |
1543 | goto out_unlock; |
1544 | } |
1545 | } |
1546 | |
1547 | get_rq: |
1548 | /* |
1549 | * This sync check and mask will be re-done in init_request_from_bio(), |
1550 | * but we need to set it earlier to expose the sync flag to the |
1551 | * rq allocator and io schedulers. |
1552 | */ |
1553 | rw_flags = bio_data_dir(bio); |
1554 | if (sync) |
1555 | rw_flags |= REQ_SYNC; |
1556 | |
1557 | /* |
1558 | * Grab a free request. This is might sleep but can not fail. |
1559 | * Returns with the queue unlocked. |
1560 | */ |
1561 | req = get_request(q, rw_flags, bio, GFP_NOIO); |
1562 | if (unlikely(!req)) { |
1563 | bio_endio(bio, -ENODEV); /* @q is dead */ |
1564 | goto out_unlock; |
1565 | } |
1566 | |
1567 | /* |
1568 | * After dropping the lock and possibly sleeping here, our request |
1569 | * may now be mergeable after it had proven unmergeable (above). |
1570 | * We don't worry about that case for efficiency. It won't happen |
1571 | * often, and the elevators are able to handle it. |
1572 | */ |
1573 | init_request_from_bio(req, bio); |
1574 | |
1575 | if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) |
1576 | req->cpu = raw_smp_processor_id(); |
1577 | |
1578 | plug = current->plug; |
1579 | if (plug) { |
1580 | /* |
1581 | * If this is the first request added after a plug, fire |
1582 | * of a plug trace. |
1583 | */ |
1584 | if (!request_count) |
1585 | trace_block_plug(q); |
1586 | else { |
1587 | if (request_count >= BLK_MAX_REQUEST_COUNT) { |
1588 | blk_flush_plug_list(plug, false); |
1589 | trace_block_plug(q); |
1590 | } |
1591 | } |
1592 | list_add_tail(&req->queuelist, &plug->list); |
1593 | blk_account_io_start(req, true); |
1594 | } else { |
1595 | spin_lock_irq(q->queue_lock); |
1596 | add_acct_request(q, req, where); |
1597 | __blk_run_queue(q); |
1598 | out_unlock: |
1599 | spin_unlock_irq(q->queue_lock); |
1600 | } |
1601 | } |
1602 | EXPORT_SYMBOL_GPL(blk_queue_bio); /* for device mapper only */ |
1603 | |
1604 | /* |
1605 | * If bio->bi_dev is a partition, remap the location |
1606 | */ |
1607 | static inline void blk_partition_remap(struct bio *bio) |
1608 | { |
1609 | struct block_device *bdev = bio->bi_bdev; |
1610 | |
1611 | if (bio_sectors(bio) && bdev != bdev->bd_contains) { |
1612 | struct hd_struct *p = bdev->bd_part; |
1613 | |
1614 | bio->bi_iter.bi_sector += p->start_sect; |
1615 | bio->bi_bdev = bdev->bd_contains; |
1616 | |
1617 | trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio, |
1618 | bdev->bd_dev, |
1619 | bio->bi_iter.bi_sector - p->start_sect); |
1620 | } |
1621 | } |
1622 | |
1623 | static void handle_bad_sector(struct bio *bio) |
1624 | { |
1625 | char b[BDEVNAME_SIZE]; |
1626 | |
1627 | printk(KERN_INFO "attempt to access beyond end of device\n"); |
1628 | printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n", |
1629 | bdevname(bio->bi_bdev, b), |
1630 | bio->bi_rw, |
1631 | (unsigned long long)bio_end_sector(bio), |
1632 | (long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9)); |
1633 | |
1634 | set_bit(BIO_EOF, &bio->bi_flags); |
1635 | } |
1636 | |
1637 | #ifdef CONFIG_FAIL_MAKE_REQUEST |
1638 | |
1639 | static DECLARE_FAULT_ATTR(fail_make_request); |
1640 | |
1641 | static int __init setup_fail_make_request(char *str) |
1642 | { |
1643 | return setup_fault_attr(&fail_make_request, str); |
1644 | } |
1645 | __setup("fail_make_request=", setup_fail_make_request); |
1646 | |
1647 | static bool should_fail_request(struct hd_struct *part, unsigned int bytes) |
1648 | { |
1649 | return part->make_it_fail && should_fail(&fail_make_request, bytes); |
1650 | } |
1651 | |
1652 | static int __init fail_make_request_debugfs(void) |
1653 | { |
1654 | struct dentry *dir = fault_create_debugfs_attr("fail_make_request", |
1655 | NULL, &fail_make_request); |
1656 | |
1657 | return IS_ERR(dir) ? PTR_ERR(dir) : 0; |
1658 | } |
1659 | |
1660 | late_initcall(fail_make_request_debugfs); |
1661 | |
1662 | #else /* CONFIG_FAIL_MAKE_REQUEST */ |
1663 | |
1664 | static inline bool should_fail_request(struct hd_struct *part, |
1665 | unsigned int bytes) |
1666 | { |
1667 | return false; |
1668 | } |
1669 | |
1670 | #endif /* CONFIG_FAIL_MAKE_REQUEST */ |
1671 | |
1672 | /* |
1673 | * Check whether this bio extends beyond the end of the device. |
1674 | */ |
1675 | static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors) |
1676 | { |
1677 | sector_t maxsector; |
1678 | |
1679 | if (!nr_sectors) |
1680 | return 0; |
1681 | |
1682 | /* Test device or partition size, when known. */ |
1683 | maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9; |
1684 | if (maxsector) { |
1685 | sector_t sector = bio->bi_iter.bi_sector; |
1686 | |
1687 | if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { |
1688 | /* |
1689 | * This may well happen - the kernel calls bread() |
1690 | * without checking the size of the device, e.g., when |
1691 | * mounting a device. |
1692 | */ |
1693 | handle_bad_sector(bio); |
1694 | return 1; |
1695 | } |
1696 | } |
1697 | |
1698 | return 0; |
1699 | } |
1700 | |
1701 | static noinline_for_stack bool |
1702 | generic_make_request_checks(struct bio *bio) |
1703 | { |
1704 | struct request_queue *q; |
1705 | int nr_sectors = bio_sectors(bio); |
1706 | int err = -EIO; |
1707 | char b[BDEVNAME_SIZE]; |
1708 | struct hd_struct *part; |
1709 | |
1710 | might_sleep(); |
1711 | |
1712 | if (bio_check_eod(bio, nr_sectors)) |
1713 | goto end_io; |
1714 | |
1715 | q = bdev_get_queue(bio->bi_bdev); |
1716 | if (unlikely(!q)) { |
1717 | printk(KERN_ERR |
1718 | "generic_make_request: Trying to access " |
1719 | "nonexistent block-device %s (%Lu)\n", |
1720 | bdevname(bio->bi_bdev, b), |
1721 | (long long) bio->bi_iter.bi_sector); |
1722 | goto end_io; |
1723 | } |
1724 | |
1725 | if (likely(bio_is_rw(bio) && |
1726 | nr_sectors > queue_max_hw_sectors(q))) { |
1727 | printk(KERN_ERR "bio too big device %s (%u > %u)\n", |
1728 | bdevname(bio->bi_bdev, b), |
1729 | bio_sectors(bio), |
1730 | queue_max_hw_sectors(q)); |
1731 | goto end_io; |
1732 | } |
1733 | |
1734 | part = bio->bi_bdev->bd_part; |
1735 | if (should_fail_request(part, bio->bi_iter.bi_size) || |
1736 | should_fail_request(&part_to_disk(part)->part0, |
1737 | bio->bi_iter.bi_size)) |
1738 | goto end_io; |
1739 | |
1740 | /* |
1741 | * If this device has partitions, remap block n |
1742 | * of partition p to block n+start(p) of the disk. |
1743 | */ |
1744 | blk_partition_remap(bio); |
1745 | |
1746 | if (bio_check_eod(bio, nr_sectors)) |
1747 | goto end_io; |
1748 | |
1749 | /* |
1750 | * Filter flush bio's early so that make_request based |
1751 | * drivers without flush support don't have to worry |
1752 | * about them. |
1753 | */ |
1754 | if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) { |
1755 | bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA); |
1756 | if (!nr_sectors) { |
1757 | err = 0; |
1758 | goto end_io; |
1759 | } |
1760 | } |
1761 | |
1762 | if ((bio->bi_rw & REQ_DISCARD) && |
1763 | (!blk_queue_discard(q) || |
1764 | ((bio->bi_rw & REQ_SECURE) && !blk_queue_secdiscard(q)))) { |
1765 | err = -EOPNOTSUPP; |
1766 | goto end_io; |
1767 | } |
1768 | |
1769 | if (bio->bi_rw & REQ_WRITE_SAME && !bdev_write_same(bio->bi_bdev)) { |
1770 | err = -EOPNOTSUPP; |
1771 | goto end_io; |
1772 | } |
1773 | |
1774 | /* |
1775 | * Various block parts want %current->io_context and lazy ioc |
1776 | * allocation ends up trading a lot of pain for a small amount of |
1777 | * memory. Just allocate it upfront. This may fail and block |
1778 | * layer knows how to live with it. |
1779 | */ |
1780 | create_io_context(GFP_ATOMIC, q->node); |
1781 | |
1782 | if (blk_throtl_bio(q, bio)) |
1783 | return false; /* throttled, will be resubmitted later */ |
1784 | |
1785 | trace_block_bio_queue(q, bio); |
1786 | return true; |
1787 | |
1788 | end_io: |
1789 | bio_endio(bio, err); |
1790 | return false; |
1791 | } |
1792 | |
1793 | /** |
1794 | * generic_make_request - hand a buffer to its device driver for I/O |
1795 | * @bio: The bio describing the location in memory and on the device. |
1796 | * |
1797 | * generic_make_request() is used to make I/O requests of block |
1798 | * devices. It is passed a &struct bio, which describes the I/O that needs |
1799 | * to be done. |
1800 | * |
1801 | * generic_make_request() does not return any status. The |
1802 | * success/failure status of the request, along with notification of |
1803 | * completion, is delivered asynchronously through the bio->bi_end_io |
1804 | * function described (one day) else where. |
1805 | * |
1806 | * The caller of generic_make_request must make sure that bi_io_vec |
1807 | * are set to describe the memory buffer, and that bi_dev and bi_sector are |
1808 | * set to describe the device address, and the |
1809 | * bi_end_io and optionally bi_private are set to describe how |
1810 | * completion notification should be signaled. |
1811 | * |
1812 | * generic_make_request and the drivers it calls may use bi_next if this |
1813 | * bio happens to be merged with someone else, and may resubmit the bio to |
1814 | * a lower device by calling into generic_make_request recursively, which |
1815 | * means the bio should NOT be touched after the call to ->make_request_fn. |
1816 | */ |
1817 | void generic_make_request(struct bio *bio) |
1818 | { |
1819 | struct bio_list bio_list_on_stack; |
1820 | |
1821 | if (!generic_make_request_checks(bio)) |
1822 | return; |
1823 | |
1824 | /* |
1825 | * We only want one ->make_request_fn to be active at a time, else |
1826 | * stack usage with stacked devices could be a problem. So use |
1827 | * current->bio_list to keep a list of requests submited by a |
1828 | * make_request_fn function. current->bio_list is also used as a |
1829 | * flag to say if generic_make_request is currently active in this |
1830 | * task or not. If it is NULL, then no make_request is active. If |
1831 | * it is non-NULL, then a make_request is active, and new requests |
1832 | * should be added at the tail |
1833 | */ |
1834 | if (current->bio_list) { |
1835 | bio_list_add(current->bio_list, bio); |
1836 | return; |
1837 | } |
1838 | |
1839 | /* following loop may be a bit non-obvious, and so deserves some |
1840 | * explanation. |
1841 | * Before entering the loop, bio->bi_next is NULL (as all callers |
1842 | * ensure that) so we have a list with a single bio. |
1843 | * We pretend that we have just taken it off a longer list, so |
1844 | * we assign bio_list to a pointer to the bio_list_on_stack, |
1845 | * thus initialising the bio_list of new bios to be |
1846 | * added. ->make_request() may indeed add some more bios |
1847 | * through a recursive call to generic_make_request. If it |
1848 | * did, we find a non-NULL value in bio_list and re-enter the loop |
1849 | * from the top. In this case we really did just take the bio |
1850 | * of the top of the list (no pretending) and so remove it from |
1851 | * bio_list, and call into ->make_request() again. |
1852 | */ |
1853 | BUG_ON(bio->bi_next); |
1854 | bio_list_init(&bio_list_on_stack); |
1855 | current->bio_list = &bio_list_on_stack; |
1856 | do { |
1857 | struct request_queue *q = bdev_get_queue(bio->bi_bdev); |
1858 | |
1859 | q->make_request_fn(q, bio); |
1860 | |
1861 | bio = bio_list_pop(current->bio_list); |
1862 | } while (bio); |
1863 | current->bio_list = NULL; /* deactivate */ |
1864 | } |
1865 | EXPORT_SYMBOL(generic_make_request); |
1866 | |
1867 | /** |
1868 | * submit_bio - submit a bio to the block device layer for I/O |
1869 | * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) |
1870 | * @bio: The &struct bio which describes the I/O |
1871 | * |
1872 | * submit_bio() is very similar in purpose to generic_make_request(), and |
1873 | * uses that function to do most of the work. Both are fairly rough |
1874 | * interfaces; @bio must be presetup and ready for I/O. |
1875 | * |
1876 | */ |
1877 | void submit_bio(int rw, struct bio *bio) |
1878 | { |
1879 | bio->bi_rw |= rw; |
1880 | |
1881 | /* |
1882 | * If it's a regular read/write or a barrier with data attached, |
1883 | * go through the normal accounting stuff before submission. |
1884 | */ |
1885 | if (bio_has_data(bio)) { |
1886 | unsigned int count; |
1887 | |
1888 | if (unlikely(rw & REQ_WRITE_SAME)) |
1889 | count = bdev_logical_block_size(bio->bi_bdev) >> 9; |
1890 | else |
1891 | count = bio_sectors(bio); |
1892 | |
1893 | if (rw & WRITE) { |
1894 | count_vm_events(PGPGOUT, count); |
1895 | } else { |
1896 | task_io_account_read(bio->bi_iter.bi_size); |
1897 | count_vm_events(PGPGIN, count); |
1898 | } |
1899 | |
1900 | if (unlikely(block_dump)) { |
1901 | char b[BDEVNAME_SIZE]; |
1902 | printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n", |
1903 | current->comm, task_pid_nr(current), |
1904 | (rw & WRITE) ? "WRITE" : "READ", |
1905 | (unsigned long long)bio->bi_iter.bi_sector, |
1906 | bdevname(bio->bi_bdev, b), |
1907 | count); |
1908 | } |
1909 | } |
1910 | |
1911 | generic_make_request(bio); |
1912 | } |
1913 | EXPORT_SYMBOL(submit_bio); |
1914 | |
1915 | /** |
1916 | * blk_rq_check_limits - Helper function to check a request for the queue limit |
1917 | * @q: the queue |
1918 | * @rq: the request being checked |
1919 | * |
1920 | * Description: |
1921 | * @rq may have been made based on weaker limitations of upper-level queues |
1922 | * in request stacking drivers, and it may violate the limitation of @q. |
1923 | * Since the block layer and the underlying device driver trust @rq |
1924 | * after it is inserted to @q, it should be checked against @q before |
1925 | * the insertion using this generic function. |
1926 | * |
1927 | * This function should also be useful for request stacking drivers |
1928 | * in some cases below, so export this function. |
1929 | * Request stacking drivers like request-based dm may change the queue |
1930 | * limits while requests are in the queue (e.g. dm's table swapping). |
1931 | * Such request stacking drivers should check those requests against |
1932 | * the new queue limits again when they dispatch those requests, |
1933 | * although such checkings are also done against the old queue limits |
1934 | * when submitting requests. |
1935 | */ |
1936 | int blk_rq_check_limits(struct request_queue *q, struct request *rq) |
1937 | { |
1938 | if (!rq_mergeable(rq)) |
1939 | return 0; |
1940 | |
1941 | if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, rq->cmd_flags)) { |
1942 | printk(KERN_ERR "%s: over max size limit.\n", __func__); |
1943 | return -EIO; |
1944 | } |
1945 | |
1946 | /* |
1947 | * queue's settings related to segment counting like q->bounce_pfn |
1948 | * may differ from that of other stacking queues. |
1949 | * Recalculate it to check the request correctly on this queue's |
1950 | * limitation. |
1951 | */ |
1952 | blk_recalc_rq_segments(rq); |
1953 | if (rq->nr_phys_segments > queue_max_segments(q)) { |
1954 | printk(KERN_ERR "%s: over max segments limit.\n", __func__); |
1955 | return -EIO; |
1956 | } |
1957 | |
1958 | return 0; |
1959 | } |
1960 | EXPORT_SYMBOL_GPL(blk_rq_check_limits); |
1961 | |
1962 | /** |
1963 | * blk_insert_cloned_request - Helper for stacking drivers to submit a request |
1964 | * @q: the queue to submit the request |
1965 | * @rq: the request being queued |
1966 | */ |
1967 | int blk_insert_cloned_request(struct request_queue *q, struct request *rq) |
1968 | { |
1969 | unsigned long flags; |
1970 | int where = ELEVATOR_INSERT_BACK; |
1971 | |
1972 | if (blk_rq_check_limits(q, rq)) |
1973 | return -EIO; |
1974 | |
1975 | if (rq->rq_disk && |
1976 | should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq))) |
1977 | return -EIO; |
1978 | |
1979 | spin_lock_irqsave(q->queue_lock, flags); |
1980 | if (unlikely(blk_queue_dying(q))) { |
1981 | spin_unlock_irqrestore(q->queue_lock, flags); |
1982 | return -ENODEV; |
1983 | } |
1984 | |
1985 | /* |
1986 | * Submitting request must be dequeued before calling this function |
1987 | * because it will be linked to another request_queue |
1988 | */ |
1989 | BUG_ON(blk_queued_rq(rq)); |
1990 | |
1991 | if (rq->cmd_flags & (REQ_FLUSH|REQ_FUA)) |
1992 | where = ELEVATOR_INSERT_FLUSH; |
1993 | |
1994 | add_acct_request(q, rq, where); |
1995 | if (where == ELEVATOR_INSERT_FLUSH) |
1996 | __blk_run_queue(q); |
1997 | spin_unlock_irqrestore(q->queue_lock, flags); |
1998 | |
1999 | return 0; |
2000 | } |
2001 | EXPORT_SYMBOL_GPL(blk_insert_cloned_request); |
2002 | |
2003 | /** |
2004 | * blk_rq_err_bytes - determine number of bytes till the next failure boundary |
2005 | * @rq: request to examine |
2006 | * |
2007 | * Description: |
2008 | * A request could be merge of IOs which require different failure |
2009 | * handling. This function determines the number of bytes which |
2010 | * can be failed from the beginning of the request without |
2011 | * crossing into area which need to be retried further. |
2012 | * |
2013 | * Return: |
2014 | * The number of bytes to fail. |
2015 | * |
2016 | * Context: |
2017 | * queue_lock must be held. |
2018 | */ |
2019 | unsigned int blk_rq_err_bytes(const struct request *rq) |
2020 | { |
2021 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; |
2022 | unsigned int bytes = 0; |
2023 | struct bio *bio; |
2024 | |
2025 | if (!(rq->cmd_flags & REQ_MIXED_MERGE)) |
2026 | return blk_rq_bytes(rq); |
2027 | |
2028 | /* |
2029 | * Currently the only 'mixing' which can happen is between |
2030 | * different fastfail types. We can safely fail portions |
2031 | * which have all the failfast bits that the first one has - |
2032 | * the ones which are at least as eager to fail as the first |
2033 | * one. |
2034 | */ |
2035 | for (bio = rq->bio; bio; bio = bio->bi_next) { |
2036 | if ((bio->bi_rw & ff) != ff) |
2037 | break; |
2038 | bytes += bio->bi_iter.bi_size; |
2039 | } |
2040 | |
2041 | /* this could lead to infinite loop */ |
2042 | BUG_ON(blk_rq_bytes(rq) && !bytes); |
2043 | return bytes; |
2044 | } |
2045 | EXPORT_SYMBOL_GPL(blk_rq_err_bytes); |
2046 | |
2047 | void blk_account_io_completion(struct request *req, unsigned int bytes) |
2048 | { |
2049 | if (blk_do_io_stat(req)) { |
2050 | const int rw = rq_data_dir(req); |
2051 | struct hd_struct *part; |
2052 | int cpu; |
2053 | |
2054 | cpu = part_stat_lock(); |
2055 | part = req->part; |
2056 | part_stat_add(cpu, part, sectors[rw], bytes >> 9); |
2057 | part_stat_unlock(); |
2058 | } |
2059 | } |
2060 | |
2061 | void blk_account_io_done(struct request *req) |
2062 | { |
2063 | /* |
2064 | * Account IO completion. flush_rq isn't accounted as a |
2065 | * normal IO on queueing nor completion. Accounting the |
2066 | * containing request is enough. |
2067 | */ |
2068 | if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) { |
2069 | unsigned long duration = jiffies - req->start_time; |
2070 | const int rw = rq_data_dir(req); |
2071 | struct hd_struct *part; |
2072 | int cpu; |
2073 | |
2074 | cpu = part_stat_lock(); |
2075 | part = req->part; |
2076 | |
2077 | part_stat_inc(cpu, part, ios[rw]); |
2078 | part_stat_add(cpu, part, ticks[rw], duration); |
2079 | part_round_stats(cpu, part); |
2080 | part_dec_in_flight(part, rw); |
2081 | |
2082 | hd_struct_put(part); |
2083 | part_stat_unlock(); |
2084 | } |
2085 | } |
2086 | |
2087 | #ifdef CONFIG_PM_RUNTIME |
2088 | /* |
2089 | * Don't process normal requests when queue is suspended |
2090 | * or in the process of suspending/resuming |
2091 | */ |
2092 | static struct request *blk_pm_peek_request(struct request_queue *q, |
2093 | struct request *rq) |
2094 | { |
2095 | if (q->dev && (q->rpm_status == RPM_SUSPENDED || |
2096 | (q->rpm_status != RPM_ACTIVE && !(rq->cmd_flags & REQ_PM)))) |
2097 | return NULL; |
2098 | else |
2099 | return rq; |
2100 | } |
2101 | #else |
2102 | static inline struct request *blk_pm_peek_request(struct request_queue *q, |
2103 | struct request *rq) |
2104 | { |
2105 | return rq; |
2106 | } |
2107 | #endif |
2108 | |
2109 | void blk_account_io_start(struct request *rq, bool new_io) |
2110 | { |
2111 | struct hd_struct *part; |
2112 | int rw = rq_data_dir(rq); |
2113 | int cpu; |
2114 | |
2115 | if (!blk_do_io_stat(rq)) |
2116 | return; |
2117 | |
2118 | cpu = part_stat_lock(); |
2119 | |
2120 | if (!new_io) { |
2121 | part = rq->part; |
2122 | part_stat_inc(cpu, part, merges[rw]); |
2123 | } else { |
2124 | part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); |
2125 | if (!hd_struct_try_get(part)) { |
2126 | /* |
2127 | * The partition is already being removed, |
2128 | * the request will be accounted on the disk only |
2129 | * |
2130 | * We take a reference on disk->part0 although that |
2131 | * partition will never be deleted, so we can treat |
2132 | * it as any other partition. |
2133 | */ |
2134 | part = &rq->rq_disk->part0; |
2135 | hd_struct_get(part); |
2136 | } |
2137 | part_round_stats(cpu, part); |
2138 | part_inc_in_flight(part, rw); |
2139 | rq->part = part; |
2140 | } |
2141 | |
2142 | part_stat_unlock(); |
2143 | } |
2144 | |
2145 | /** |
2146 | * blk_peek_request - peek at the top of a request queue |
2147 | * @q: request queue to peek at |
2148 | * |
2149 | * Description: |
2150 | * Return the request at the top of @q. The returned request |
2151 | * should be started using blk_start_request() before LLD starts |
2152 | * processing it. |
2153 | * |
2154 | * Return: |
2155 | * Pointer to the request at the top of @q if available. Null |
2156 | * otherwise. |
2157 | * |
2158 | * Context: |
2159 | * queue_lock must be held. |
2160 | */ |
2161 | struct request *blk_peek_request(struct request_queue *q) |
2162 | { |
2163 | struct request *rq; |
2164 | int ret; |
2165 | |
2166 | while ((rq = __elv_next_request(q)) != NULL) { |
2167 | |
2168 | rq = blk_pm_peek_request(q, rq); |
2169 | if (!rq) |
2170 | break; |
2171 | |
2172 | if (!(rq->cmd_flags & REQ_STARTED)) { |
2173 | /* |
2174 | * This is the first time the device driver |
2175 | * sees this request (possibly after |
2176 | * requeueing). Notify IO scheduler. |
2177 | */ |
2178 | if (rq->cmd_flags & REQ_SORTED) |
2179 | elv_activate_rq(q, rq); |
2180 | |
2181 | /* |
2182 | * just mark as started even if we don't start |
2183 | * it, a request that has been delayed should |
2184 | * not be passed by new incoming requests |
2185 | */ |
2186 | rq->cmd_flags |= REQ_STARTED; |
2187 | trace_block_rq_issue(q, rq); |
2188 | } |
2189 | |
2190 | if (!q->boundary_rq || q->boundary_rq == rq) { |
2191 | q->end_sector = rq_end_sector(rq); |
2192 | q->boundary_rq = NULL; |
2193 | } |
2194 | |
2195 | if (rq->cmd_flags & REQ_DONTPREP) |
2196 | break; |
2197 | |
2198 | if (q->dma_drain_size && blk_rq_bytes(rq)) { |
2199 | /* |
2200 | * make sure space for the drain appears we |
2201 | * know we can do this because max_hw_segments |
2202 | * has been adjusted to be one fewer than the |
2203 | * device can handle |
2204 | */ |
2205 | rq->nr_phys_segments++; |
2206 | } |
2207 | |
2208 | if (!q->prep_rq_fn) |
2209 | break; |
2210 | |
2211 | ret = q->prep_rq_fn(q, rq); |
2212 | if (ret == BLKPREP_OK) { |
2213 | break; |
2214 | } else if (ret == BLKPREP_DEFER) { |
2215 | /* |
2216 | * the request may have been (partially) prepped. |
2217 | * we need to keep this request in the front to |
2218 | * avoid resource deadlock. REQ_STARTED will |
2219 | * prevent other fs requests from passing this one. |
2220 | */ |
2221 | if (q->dma_drain_size && blk_rq_bytes(rq) && |
2222 | !(rq->cmd_flags & REQ_DONTPREP)) { |
2223 | /* |
2224 | * remove the space for the drain we added |
2225 | * so that we don't add it again |
2226 | */ |
2227 | --rq->nr_phys_segments; |
2228 | } |
2229 | |
2230 | rq = NULL; |
2231 | break; |
2232 | } else if (ret == BLKPREP_KILL) { |
2233 | rq->cmd_flags |= REQ_QUIET; |
2234 | /* |
2235 | * Mark this request as started so we don't trigger |
2236 | * any debug logic in the end I/O path. |
2237 | */ |
2238 | blk_start_request(rq); |
2239 | __blk_end_request_all(rq, -EIO); |
2240 | } else { |
2241 | printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); |
2242 | break; |
2243 | } |
2244 | } |
2245 | |
2246 | return rq; |
2247 | } |
2248 | EXPORT_SYMBOL(blk_peek_request); |
2249 | |
2250 | void blk_dequeue_request(struct request *rq) |
2251 | { |
2252 | struct request_queue *q = rq->q; |
2253 | |
2254 | BUG_ON(list_empty(&rq->queuelist)); |
2255 | BUG_ON(ELV_ON_HASH(rq)); |
2256 | |
2257 | list_del_init(&rq->queuelist); |
2258 | |
2259 | /* |
2260 | * the time frame between a request being removed from the lists |
2261 | * and to it is freed is accounted as io that is in progress at |
2262 | * the driver side. |
2263 | */ |
2264 | if (blk_account_rq(rq)) { |
2265 | q->in_flight[rq_is_sync(rq)]++; |
2266 | set_io_start_time_ns(rq); |
2267 | } |
2268 | } |
2269 | |
2270 | /** |
2271 | * blk_start_request - start request processing on the driver |
2272 | * @req: request to dequeue |
2273 | * |
2274 | * Description: |
2275 | * Dequeue @req and start timeout timer on it. This hands off the |
2276 | * request to the driver. |
2277 | * |
2278 | * Block internal functions which don't want to start timer should |
2279 | * call blk_dequeue_request(). |
2280 | * |
2281 | * Context: |
2282 | * queue_lock must be held. |
2283 | */ |
2284 | void blk_start_request(struct request *req) |
2285 | { |
2286 | blk_dequeue_request(req); |
2287 | |
2288 | /* |
2289 | * We are now handing the request to the hardware, initialize |
2290 | * resid_len to full count and add the timeout handler. |
2291 | */ |
2292 | req->resid_len = blk_rq_bytes(req); |
2293 | if (unlikely(blk_bidi_rq(req))) |
2294 | req->next_rq->resid_len = blk_rq_bytes(req->next_rq); |
2295 | |
2296 | BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags)); |
2297 | blk_add_timer(req); |
2298 | } |
2299 | EXPORT_SYMBOL(blk_start_request); |
2300 | |
2301 | /** |
2302 | * blk_fetch_request - fetch a request from a request queue |
2303 | * @q: request queue to fetch a request from |
2304 | * |
2305 | * Description: |
2306 | * Return the request at the top of @q. The request is started on |
2307 | * return and LLD can start processing it immediately. |
2308 | * |
2309 | * Return: |
2310 | * Pointer to the request at the top of @q if available. Null |
2311 | * otherwise. |
2312 | * |
2313 | * Context: |
2314 | * queue_lock must be held. |
2315 | */ |
2316 | struct request *blk_fetch_request(struct request_queue *q) |
2317 | { |
2318 | struct request *rq; |
2319 | |
2320 | rq = blk_peek_request(q); |
2321 | if (rq) |
2322 | blk_start_request(rq); |
2323 | return rq; |
2324 | } |
2325 | EXPORT_SYMBOL(blk_fetch_request); |
2326 | |
2327 | /** |
2328 | * blk_update_request - Special helper function for request stacking drivers |
2329 | * @req: the request being processed |
2330 | * @error: %0 for success, < %0 for error |
2331 | * @nr_bytes: number of bytes to complete @req |
2332 | * |
2333 | * Description: |
2334 | * Ends I/O on a number of bytes attached to @req, but doesn't complete |
2335 | * the request structure even if @req doesn't have leftover. |
2336 | * If @req has leftover, sets it up for the next range of segments. |
2337 | * |
2338 | * This special helper function is only for request stacking drivers |
2339 | * (e.g. request-based dm) so that they can handle partial completion. |
2340 | * Actual device drivers should use blk_end_request instead. |
2341 | * |
2342 | * Passing the result of blk_rq_bytes() as @nr_bytes guarantees |
2343 | * %false return from this function. |
2344 | * |
2345 | * Return: |
2346 | * %false - this request doesn't have any more data |
2347 | * %true - this request has more data |
2348 | **/ |
2349 | bool blk_update_request(struct request *req, int error, unsigned int nr_bytes) |
2350 | { |
2351 | int total_bytes; |
2352 | |
2353 | if (!req->bio) |
2354 | return false; |
2355 | |
2356 | trace_block_rq_complete(req->q, req, nr_bytes); |
2357 | |
2358 | /* |
2359 | * For fs requests, rq is just carrier of independent bio's |
2360 | * and each partial completion should be handled separately. |
2361 | * Reset per-request error on each partial completion. |
2362 | * |
2363 | * TODO: tj: This is too subtle. It would be better to let |
2364 | * low level drivers do what they see fit. |
2365 | */ |
2366 | if (req->cmd_type == REQ_TYPE_FS) |
2367 | req->errors = 0; |
2368 | |
2369 | if (error && req->cmd_type == REQ_TYPE_FS && |
2370 | !(req->cmd_flags & REQ_QUIET)) { |
2371 | char *error_type; |
2372 | |
2373 | switch (error) { |
2374 | case -ENOLINK: |
2375 | error_type = "recoverable transport"; |
2376 | break; |
2377 | case -EREMOTEIO: |
2378 | error_type = "critical target"; |
2379 | break; |
2380 | case -EBADE: |
2381 | error_type = "critical nexus"; |
2382 | break; |
2383 | case -ETIMEDOUT: |
2384 | error_type = "timeout"; |
2385 | break; |
2386 | case -ENOSPC: |
2387 | error_type = "critical space allocation"; |
2388 | break; |
2389 | case -ENODATA: |
2390 | error_type = "critical medium"; |
2391 | break; |
2392 | case -EIO: |
2393 | default: |
2394 | error_type = "I/O"; |
2395 | break; |
2396 | } |
2397 | printk_ratelimited(KERN_ERR "end_request: %s error, dev %s, sector %llu\n", |
2398 | error_type, req->rq_disk ? |
2399 | req->rq_disk->disk_name : "?", |
2400 | (unsigned long long)blk_rq_pos(req)); |
2401 | |
2402 | } |
2403 | |
2404 | blk_account_io_completion(req, nr_bytes); |
2405 | |
2406 | total_bytes = 0; |
2407 | while (req->bio) { |
2408 | struct bio *bio = req->bio; |
2409 | unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes); |
2410 | |
2411 | if (bio_bytes == bio->bi_iter.bi_size) |
2412 | req->bio = bio->bi_next; |
2413 | |
2414 | req_bio_endio(req, bio, bio_bytes, error); |
2415 | |
2416 | total_bytes += bio_bytes; |
2417 | nr_bytes -= bio_bytes; |
2418 | |
2419 | if (!nr_bytes) |
2420 | break; |
2421 | } |
2422 | |
2423 | /* |
2424 | * completely done |
2425 | */ |
2426 | if (!req->bio) { |
2427 | /* |
2428 | * Reset counters so that the request stacking driver |
2429 | * can find how many bytes remain in the request |
2430 | * later. |
2431 | */ |
2432 | req->__data_len = 0; |
2433 | return false; |
2434 | } |
2435 | |
2436 | req->__data_len -= total_bytes; |
2437 | req->buffer = bio_data(req->bio); |
2438 | |
2439 | /* update sector only for requests with clear definition of sector */ |
2440 | if (req->cmd_type == REQ_TYPE_FS) |
2441 | req->__sector += total_bytes >> 9; |
2442 | |
2443 | /* mixed attributes always follow the first bio */ |
2444 | if (req->cmd_flags & REQ_MIXED_MERGE) { |
2445 | req->cmd_flags &= ~REQ_FAILFAST_MASK; |
2446 | req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK; |
2447 | } |
2448 | |
2449 | /* |
2450 | * If total number of sectors is less than the first segment |
2451 | * size, something has gone terribly wrong. |
2452 | */ |
2453 | if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { |
2454 | blk_dump_rq_flags(req, "request botched"); |
2455 | req->__data_len = blk_rq_cur_bytes(req); |
2456 | } |
2457 | |
2458 | /* recalculate the number of segments */ |
2459 | blk_recalc_rq_segments(req); |
2460 | |
2461 | return true; |
2462 | } |
2463 | EXPORT_SYMBOL_GPL(blk_update_request); |
2464 | |
2465 | static bool blk_update_bidi_request(struct request *rq, int error, |
2466 | unsigned int nr_bytes, |
2467 | unsigned int bidi_bytes) |
2468 | { |
2469 | if (blk_update_request(rq, error, nr_bytes)) |
2470 | return true; |
2471 | |
2472 | /* Bidi request must be completed as a whole */ |
2473 | if (unlikely(blk_bidi_rq(rq)) && |
2474 | blk_update_request(rq->next_rq, error, bidi_bytes)) |
2475 | return true; |
2476 | |
2477 | if (blk_queue_add_random(rq->q)) |
2478 | add_disk_randomness(rq->rq_disk); |
2479 | |
2480 | return false; |
2481 | } |
2482 | |
2483 | /** |
2484 | * blk_unprep_request - unprepare a request |
2485 | * @req: the request |
2486 | * |
2487 | * This function makes a request ready for complete resubmission (or |
2488 | * completion). It happens only after all error handling is complete, |
2489 | * so represents the appropriate moment to deallocate any resources |
2490 | * that were allocated to the request in the prep_rq_fn. The queue |
2491 | * lock is held when calling this. |
2492 | */ |
2493 | void blk_unprep_request(struct request *req) |
2494 | { |
2495 | struct request_queue *q = req->q; |
2496 | |
2497 | req->cmd_flags &= ~REQ_DONTPREP; |
2498 | if (q->unprep_rq_fn) |
2499 | q->unprep_rq_fn(q, req); |
2500 | } |
2501 | EXPORT_SYMBOL_GPL(blk_unprep_request); |
2502 | |
2503 | /* |
2504 | * queue lock must be held |
2505 | */ |
2506 | static void blk_finish_request(struct request *req, int error) |
2507 | { |
2508 | if (blk_rq_tagged(req)) |
2509 | blk_queue_end_tag(req->q, req); |
2510 | |
2511 | BUG_ON(blk_queued_rq(req)); |
2512 | |
2513 | if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS) |
2514 | laptop_io_completion(&req->q->backing_dev_info); |
2515 | |
2516 | blk_delete_timer(req); |
2517 | |
2518 | if (req->cmd_flags & REQ_DONTPREP) |
2519 | blk_unprep_request(req); |
2520 | |
2521 | blk_account_io_done(req); |
2522 | |
2523 | if (req->end_io) |
2524 | req->end_io(req, error); |
2525 | else { |
2526 | if (blk_bidi_rq(req)) |
2527 | __blk_put_request(req->next_rq->q, req->next_rq); |
2528 | |
2529 | __blk_put_request(req->q, req); |
2530 | } |
2531 | } |
2532 | |
2533 | /** |
2534 | * blk_end_bidi_request - Complete a bidi request |
2535 | * @rq: the request to complete |
2536 | * @error: %0 for success, < %0 for error |
2537 | * @nr_bytes: number of bytes to complete @rq |
2538 | * @bidi_bytes: number of bytes to complete @rq->next_rq |
2539 | * |
2540 | * Description: |
2541 | * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. |
2542 | * Drivers that supports bidi can safely call this member for any |
2543 | * type of request, bidi or uni. In the later case @bidi_bytes is |
2544 | * just ignored. |
2545 | * |
2546 | * Return: |
2547 | * %false - we are done with this request |
2548 | * %true - still buffers pending for this request |
2549 | **/ |
2550 | static bool blk_end_bidi_request(struct request *rq, int error, |
2551 | unsigned int nr_bytes, unsigned int bidi_bytes) |
2552 | { |
2553 | struct request_queue *q = rq->q; |
2554 | unsigned long flags; |
2555 | |
2556 | if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) |
2557 | return true; |
2558 | |
2559 | spin_lock_irqsave(q->queue_lock, flags); |
2560 | blk_finish_request(rq, error); |
2561 | spin_unlock_irqrestore(q->queue_lock, flags); |
2562 | |
2563 | return false; |
2564 | } |
2565 | |
2566 | /** |
2567 | * __blk_end_bidi_request - Complete a bidi request with queue lock held |
2568 | * @rq: the request to complete |
2569 | * @error: %0 for success, < %0 for error |
2570 | * @nr_bytes: number of bytes to complete @rq |
2571 | * @bidi_bytes: number of bytes to complete @rq->next_rq |
2572 | * |
2573 | * Description: |
2574 | * Identical to blk_end_bidi_request() except that queue lock is |
2575 | * assumed to be locked on entry and remains so on return. |
2576 | * |
2577 | * Return: |
2578 | * %false - we are done with this request |
2579 | * %true - still buffers pending for this request |
2580 | **/ |
2581 | bool __blk_end_bidi_request(struct request *rq, int error, |
2582 | unsigned int nr_bytes, unsigned int bidi_bytes) |
2583 | { |
2584 | if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) |
2585 | return true; |
2586 | |
2587 | blk_finish_request(rq, error); |
2588 | |
2589 | return false; |
2590 | } |
2591 | |
2592 | /** |
2593 | * blk_end_request - Helper function for drivers to complete the request. |
2594 | * @rq: the request being processed |
2595 | * @error: %0 for success, < %0 for error |
2596 | * @nr_bytes: number of bytes to complete |
2597 | * |
2598 | * Description: |
2599 | * Ends I/O on a number of bytes attached to @rq. |
2600 | * If @rq has leftover, sets it up for the next range of segments. |
2601 | * |
2602 | * Return: |
2603 | * %false - we are done with this request |
2604 | * %true - still buffers pending for this request |
2605 | **/ |
2606 | bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes) |
2607 | { |
2608 | return blk_end_bidi_request(rq, error, nr_bytes, 0); |
2609 | } |
2610 | EXPORT_SYMBOL(blk_end_request); |
2611 | |
2612 | /** |
2613 | * blk_end_request_all - Helper function for drives to finish the request. |
2614 | * @rq: the request to finish |
2615 | * @error: %0 for success, < %0 for error |
2616 | * |
2617 | * Description: |
2618 | * Completely finish @rq. |
2619 | */ |
2620 | void blk_end_request_all(struct request *rq, int error) |
2621 | { |
2622 | bool pending; |
2623 | unsigned int bidi_bytes = 0; |
2624 | |
2625 | if (unlikely(blk_bidi_rq(rq))) |
2626 | bidi_bytes = blk_rq_bytes(rq->next_rq); |
2627 | |
2628 | pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); |
2629 | BUG_ON(pending); |
2630 | } |
2631 | EXPORT_SYMBOL(blk_end_request_all); |
2632 | |
2633 | /** |
2634 | * blk_end_request_cur - Helper function to finish the current request chunk. |
2635 | * @rq: the request to finish the current chunk for |
2636 | * @error: %0 for success, < %0 for error |
2637 | * |
2638 | * Description: |
2639 | * Complete the current consecutively mapped chunk from @rq. |
2640 | * |
2641 | * Return: |
2642 | * %false - we are done with this request |
2643 | * %true - still buffers pending for this request |
2644 | */ |
2645 | bool blk_end_request_cur(struct request *rq, int error) |
2646 | { |
2647 | return blk_end_request(rq, error, blk_rq_cur_bytes(rq)); |
2648 | } |
2649 | EXPORT_SYMBOL(blk_end_request_cur); |
2650 | |
2651 | /** |
2652 | * blk_end_request_err - Finish a request till the next failure boundary. |
2653 | * @rq: the request to finish till the next failure boundary for |
2654 | * @error: must be negative errno |
2655 | * |
2656 | * Description: |
2657 | * Complete @rq till the next failure boundary. |
2658 | * |
2659 | * Return: |
2660 | * %false - we are done with this request |
2661 | * %true - still buffers pending for this request |
2662 | */ |
2663 | bool blk_end_request_err(struct request *rq, int error) |
2664 | { |
2665 | WARN_ON(error >= 0); |
2666 | return blk_end_request(rq, error, blk_rq_err_bytes(rq)); |
2667 | } |
2668 | EXPORT_SYMBOL_GPL(blk_end_request_err); |
2669 | |
2670 | /** |
2671 | * __blk_end_request - Helper function for drivers to complete the request. |
2672 | * @rq: the request being processed |
2673 | * @error: %0 for success, < %0 for error |
2674 | * @nr_bytes: number of bytes to complete |
2675 | * |
2676 | * Description: |
2677 | * Must be called with queue lock held unlike blk_end_request(). |
2678 | * |
2679 | * Return: |
2680 | * %false - we are done with this request |
2681 | * %true - still buffers pending for this request |
2682 | **/ |
2683 | bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes) |
2684 | { |
2685 | return __blk_end_bidi_request(rq, error, nr_bytes, 0); |
2686 | } |
2687 | EXPORT_SYMBOL(__blk_end_request); |
2688 | |
2689 | /** |
2690 | * __blk_end_request_all - Helper function for drives to finish the request. |
2691 | * @rq: the request to finish |
2692 | * @error: %0 for success, < %0 for error |
2693 | * |
2694 | * Description: |
2695 | * Completely finish @rq. Must be called with queue lock held. |
2696 | */ |
2697 | void __blk_end_request_all(struct request *rq, int error) |
2698 | { |
2699 | bool pending; |
2700 | unsigned int bidi_bytes = 0; |
2701 | |
2702 | if (unlikely(blk_bidi_rq(rq))) |
2703 | bidi_bytes = blk_rq_bytes(rq->next_rq); |
2704 | |
2705 | pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); |
2706 | BUG_ON(pending); |
2707 | } |
2708 | EXPORT_SYMBOL(__blk_end_request_all); |
2709 | |
2710 | /** |
2711 | * __blk_end_request_cur - Helper function to finish the current request chunk. |
2712 | * @rq: the request to finish the current chunk for |
2713 | * @error: %0 for success, < %0 for error |
2714 | * |
2715 | * Description: |
2716 | * Complete the current consecutively mapped chunk from @rq. Must |
2717 | * be called with queue lock held. |
2718 | * |
2719 | * Return: |
2720 | * %false - we are done with this request |
2721 | * %true - still buffers pending for this request |
2722 | */ |
2723 | bool __blk_end_request_cur(struct request *rq, int error) |
2724 | { |
2725 | return __blk_end_request(rq, error, blk_rq_cur_bytes(rq)); |
2726 | } |
2727 | EXPORT_SYMBOL(__blk_end_request_cur); |
2728 | |
2729 | /** |
2730 | * __blk_end_request_err - Finish a request till the next failure boundary. |
2731 | * @rq: the request to finish till the next failure boundary for |
2732 | * @error: must be negative errno |
2733 | * |
2734 | * Description: |
2735 | * Complete @rq till the next failure boundary. Must be called |
2736 | * with queue lock held. |
2737 | * |
2738 | * Return: |
2739 | * %false - we are done with this request |
2740 | * %true - still buffers pending for this request |
2741 | */ |
2742 | bool __blk_end_request_err(struct request *rq, int error) |
2743 | { |
2744 | WARN_ON(error >= 0); |
2745 | return __blk_end_request(rq, error, blk_rq_err_bytes(rq)); |
2746 | } |
2747 | EXPORT_SYMBOL_GPL(__blk_end_request_err); |
2748 | |
2749 | void blk_rq_bio_prep(struct request_queue *q, struct request *rq, |
2750 | struct bio *bio) |
2751 | { |
2752 | /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */ |
2753 | rq->cmd_flags |= bio->bi_rw & REQ_WRITE; |
2754 | |
2755 | if (bio_has_data(bio)) { |
2756 | rq->nr_phys_segments = bio_phys_segments(q, bio); |
2757 | rq->buffer = bio_data(bio); |
2758 | } |
2759 | rq->__data_len = bio->bi_iter.bi_size; |
2760 | rq->bio = rq->biotail = bio; |
2761 | |
2762 | if (bio->bi_bdev) |
2763 | rq->rq_disk = bio->bi_bdev->bd_disk; |
2764 | } |
2765 | |
2766 | #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE |
2767 | /** |
2768 | * rq_flush_dcache_pages - Helper function to flush all pages in a request |
2769 | * @rq: the request to be flushed |
2770 | * |
2771 | * Description: |
2772 | * Flush all pages in @rq. |
2773 | */ |
2774 | void rq_flush_dcache_pages(struct request *rq) |
2775 | { |
2776 | struct req_iterator iter; |
2777 | struct bio_vec bvec; |
2778 | |
2779 | rq_for_each_segment(bvec, rq, iter) |
2780 | flush_dcache_page(bvec.bv_page); |
2781 | } |
2782 | EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); |
2783 | #endif |
2784 | |
2785 | /** |
2786 | * blk_lld_busy - Check if underlying low-level drivers of a device are busy |
2787 | * @q : the queue of the device being checked |
2788 | * |
2789 | * Description: |
2790 | * Check if underlying low-level drivers of a device are busy. |
2791 | * If the drivers want to export their busy state, they must set own |
2792 | * exporting function using blk_queue_lld_busy() first. |
2793 | * |
2794 | * Basically, this function is used only by request stacking drivers |
2795 | * to stop dispatching requests to underlying devices when underlying |
2796 | * devices are busy. This behavior helps more I/O merging on the queue |
2797 | * of the request stacking driver and prevents I/O throughput regression |
2798 | * on burst I/O load. |
2799 | * |
2800 | * Return: |
2801 | * 0 - Not busy (The request stacking driver should dispatch request) |
2802 | * 1 - Busy (The request stacking driver should stop dispatching request) |
2803 | */ |
2804 | int blk_lld_busy(struct request_queue *q) |
2805 | { |
2806 | if (q->lld_busy_fn) |
2807 | return q->lld_busy_fn(q); |
2808 | |
2809 | return 0; |
2810 | } |
2811 | EXPORT_SYMBOL_GPL(blk_lld_busy); |
2812 | |
2813 | /** |
2814 | * blk_rq_unprep_clone - Helper function to free all bios in a cloned request |
2815 | * @rq: the clone request to be cleaned up |
2816 | * |
2817 | * Description: |
2818 | * Free all bios in @rq for a cloned request. |
2819 | */ |
2820 | void blk_rq_unprep_clone(struct request *rq) |
2821 | { |
2822 | struct bio *bio; |
2823 | |
2824 | while ((bio = rq->bio) != NULL) { |
2825 | rq->bio = bio->bi_next; |
2826 | |
2827 | bio_put(bio); |
2828 | } |
2829 | } |
2830 | EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); |
2831 | |
2832 | /* |
2833 | * Copy attributes of the original request to the clone request. |
2834 | * The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied. |
2835 | */ |
2836 | static void __blk_rq_prep_clone(struct request *dst, struct request *src) |
2837 | { |
2838 | dst->cpu = src->cpu; |
2839 | dst->cmd_flags = (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE; |
2840 | dst->cmd_type = src->cmd_type; |
2841 | dst->__sector = blk_rq_pos(src); |
2842 | dst->__data_len = blk_rq_bytes(src); |
2843 | dst->nr_phys_segments = src->nr_phys_segments; |
2844 | dst->ioprio = src->ioprio; |
2845 | dst->extra_len = src->extra_len; |
2846 | } |
2847 | |
2848 | /** |
2849 | * blk_rq_prep_clone - Helper function to setup clone request |
2850 | * @rq: the request to be setup |
2851 | * @rq_src: original request to be cloned |
2852 | * @bs: bio_set that bios for clone are allocated from |
2853 | * @gfp_mask: memory allocation mask for bio |
2854 | * @bio_ctr: setup function to be called for each clone bio. |
2855 | * Returns %0 for success, non %0 for failure. |
2856 | * @data: private data to be passed to @bio_ctr |
2857 | * |
2858 | * Description: |
2859 | * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. |
2860 | * The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense) |
2861 | * are not copied, and copying such parts is the caller's responsibility. |
2862 | * Also, pages which the original bios are pointing to are not copied |
2863 | * and the cloned bios just point same pages. |
2864 | * So cloned bios must be completed before original bios, which means |
2865 | * the caller must complete @rq before @rq_src. |
2866 | */ |
2867 | int blk_rq_prep_clone(struct request *rq, struct request *rq_src, |
2868 | struct bio_set *bs, gfp_t gfp_mask, |
2869 | int (*bio_ctr)(struct bio *, struct bio *, void *), |
2870 | void *data) |
2871 | { |
2872 | struct bio *bio, *bio_src; |
2873 | |
2874 | if (!bs) |
2875 | bs = fs_bio_set; |
2876 | |
2877 | blk_rq_init(NULL, rq); |
2878 | |
2879 | __rq_for_each_bio(bio_src, rq_src) { |
2880 | bio = bio_clone_bioset(bio_src, gfp_mask, bs); |
2881 | if (!bio) |
2882 | goto free_and_out; |
2883 | |
2884 | if (bio_ctr && bio_ctr(bio, bio_src, data)) |
2885 | goto free_and_out; |
2886 | |
2887 | if (rq->bio) { |
2888 | rq->biotail->bi_next = bio; |
2889 | rq->biotail = bio; |
2890 | } else |
2891 | rq->bio = rq->biotail = bio; |
2892 | } |
2893 | |
2894 | __blk_rq_prep_clone(rq, rq_src); |
2895 | |
2896 | return 0; |
2897 | |
2898 | free_and_out: |
2899 | if (bio) |
2900 | bio_put(bio); |
2901 | blk_rq_unprep_clone(rq); |
2902 | |
2903 | return -ENOMEM; |
2904 | } |
2905 | EXPORT_SYMBOL_GPL(blk_rq_prep_clone); |
2906 | |
2907 | int kblockd_schedule_work(struct request_queue *q, struct work_struct *work) |
2908 | { |
2909 | return queue_work(kblockd_workqueue, work); |
2910 | } |
2911 | EXPORT_SYMBOL(kblockd_schedule_work); |
2912 | |
2913 | int kblockd_schedule_delayed_work(struct request_queue *q, |
2914 | struct delayed_work *dwork, unsigned long delay) |
2915 | { |
2916 | return queue_delayed_work(kblockd_workqueue, dwork, delay); |
2917 | } |
2918 | EXPORT_SYMBOL(kblockd_schedule_delayed_work); |
2919 | |
2920 | #define PLUG_MAGIC 0x91827364 |
2921 | |
2922 | /** |
2923 | * blk_start_plug - initialize blk_plug and track it inside the task_struct |
2924 | * @plug: The &struct blk_plug that needs to be initialized |
2925 | * |
2926 | * Description: |
2927 | * Tracking blk_plug inside the task_struct will help with auto-flushing the |
2928 | * pending I/O should the task end up blocking between blk_start_plug() and |
2929 | * blk_finish_plug(). This is important from a performance perspective, but |
2930 | * also ensures that we don't deadlock. For instance, if the task is blocking |
2931 | * for a memory allocation, memory reclaim could end up wanting to free a |
2932 | * page belonging to that request that is currently residing in our private |
2933 | * plug. By flushing the pending I/O when the process goes to sleep, we avoid |
2934 | * this kind of deadlock. |
2935 | */ |
2936 | void blk_start_plug(struct blk_plug *plug) |
2937 | { |
2938 | struct task_struct *tsk = current; |
2939 | |
2940 | plug->magic = PLUG_MAGIC; |
2941 | INIT_LIST_HEAD(&plug->list); |
2942 | INIT_LIST_HEAD(&plug->mq_list); |
2943 | INIT_LIST_HEAD(&plug->cb_list); |
2944 | |
2945 | /* |
2946 | * If this is a nested plug, don't actually assign it. It will be |
2947 | * flushed on its own. |
2948 | */ |
2949 | if (!tsk->plug) { |
2950 | /* |
2951 | * Store ordering should not be needed here, since a potential |
2952 | * preempt will imply a full memory barrier |
2953 | */ |
2954 | tsk->plug = plug; |
2955 | } |
2956 | } |
2957 | EXPORT_SYMBOL(blk_start_plug); |
2958 | |
2959 | static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b) |
2960 | { |
2961 | struct request *rqa = container_of(a, struct request, queuelist); |
2962 | struct request *rqb = container_of(b, struct request, queuelist); |
2963 | |
2964 | return !(rqa->q < rqb->q || |
2965 | (rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb))); |
2966 | } |
2967 | |
2968 | /* |
2969 | * If 'from_schedule' is true, then postpone the dispatch of requests |
2970 | * until a safe kblockd context. We due this to avoid accidental big |
2971 | * additional stack usage in driver dispatch, in places where the originally |
2972 | * plugger did not intend it. |
2973 | */ |
2974 | static void queue_unplugged(struct request_queue *q, unsigned int depth, |
2975 | bool from_schedule) |
2976 | __releases(q->queue_lock) |
2977 | { |
2978 | trace_block_unplug(q, depth, !from_schedule); |
2979 | |
2980 | if (from_schedule) |
2981 | blk_run_queue_async(q); |
2982 | else |
2983 | __blk_run_queue(q); |
2984 | spin_unlock(q->queue_lock); |
2985 | } |
2986 | |
2987 | static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) |
2988 | { |
2989 | LIST_HEAD(callbacks); |
2990 | |
2991 | while (!list_empty(&plug->cb_list)) { |
2992 | list_splice_init(&plug->cb_list, &callbacks); |
2993 | |
2994 | while (!list_empty(&callbacks)) { |
2995 | struct blk_plug_cb *cb = list_first_entry(&callbacks, |
2996 | struct blk_plug_cb, |
2997 | list); |
2998 | list_del(&cb->list); |
2999 | cb->callback(cb, from_schedule); |
3000 | } |
3001 | } |
3002 | } |
3003 | |
3004 | struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, |
3005 | int size) |
3006 | { |
3007 | struct blk_plug *plug = current->plug; |
3008 | struct blk_plug_cb *cb; |
3009 | |
3010 | if (!plug) |
3011 | return NULL; |
3012 | |
3013 | list_for_each_entry(cb, &plug->cb_list, list) |
3014 | if (cb->callback == unplug && cb->data == data) |
3015 | return cb; |
3016 | |
3017 | /* Not currently on the callback list */ |
3018 | BUG_ON(size < sizeof(*cb)); |
3019 | cb = kzalloc(size, GFP_ATOMIC); |
3020 | if (cb) { |
3021 | cb->data = data; |
3022 | cb->callback = unplug; |
3023 | list_add(&cb->list, &plug->cb_list); |
3024 | } |
3025 | return cb; |
3026 | } |
3027 | EXPORT_SYMBOL(blk_check_plugged); |
3028 | |
3029 | void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) |
3030 | { |
3031 | struct request_queue *q; |
3032 | unsigned long flags; |
3033 | struct request *rq; |
3034 | LIST_HEAD(list); |
3035 | unsigned int depth; |
3036 | |
3037 | BUG_ON(plug->magic != PLUG_MAGIC); |
3038 | |
3039 | flush_plug_callbacks(plug, from_schedule); |
3040 | |
3041 | if (!list_empty(&plug->mq_list)) |
3042 | blk_mq_flush_plug_list(plug, from_schedule); |
3043 | |
3044 | if (list_empty(&plug->list)) |
3045 | return; |
3046 | |
3047 | list_splice_init(&plug->list, &list); |
3048 | |
3049 | list_sort(NULL, &list, plug_rq_cmp); |
3050 | |
3051 | q = NULL; |
3052 | depth = 0; |
3053 | |
3054 | /* |
3055 | * Save and disable interrupts here, to avoid doing it for every |
3056 | * queue lock we have to take. |
3057 | */ |
3058 | local_irq_save(flags); |
3059 | while (!list_empty(&list)) { |
3060 | rq = list_entry_rq(list.next); |
3061 | list_del_init(&rq->queuelist); |
3062 | BUG_ON(!rq->q); |
3063 | if (rq->q != q) { |
3064 | /* |
3065 | * This drops the queue lock |
3066 | */ |
3067 | if (q) |
3068 | queue_unplugged(q, depth, from_schedule); |
3069 | q = rq->q; |
3070 | depth = 0; |
3071 | spin_lock(q->queue_lock); |
3072 | } |
3073 | |
3074 | /* |
3075 | * Short-circuit if @q is dead |
3076 | */ |
3077 | if (unlikely(blk_queue_dying(q))) { |
3078 | __blk_end_request_all(rq, -ENODEV); |
3079 | continue; |
3080 | } |
3081 | |
3082 | /* |
3083 | * rq is already accounted, so use raw insert |
3084 | */ |
3085 | if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) |
3086 | __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH); |
3087 | else |
3088 | __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE); |
3089 | |
3090 | depth++; |
3091 | } |
3092 | |
3093 | /* |
3094 | * This drops the queue lock |
3095 | */ |
3096 | if (q) |
3097 | queue_unplugged(q, depth, from_schedule); |
3098 | |
3099 | local_irq_restore(flags); |
3100 | } |
3101 | |
3102 | void blk_finish_plug(struct blk_plug *plug) |
3103 | { |
3104 | blk_flush_plug_list(plug, false); |
3105 | |
3106 | if (plug == current->plug) |
3107 | current->plug = NULL; |
3108 | } |
3109 | EXPORT_SYMBOL(blk_finish_plug); |
3110 | |
3111 | #ifdef CONFIG_PM_RUNTIME |
3112 | /** |
3113 | * blk_pm_runtime_init - Block layer runtime PM initialization routine |
3114 | * @q: the queue of the device |
3115 | * @dev: the device the queue belongs to |
3116 | * |
3117 | * Description: |
3118 | * Initialize runtime-PM-related fields for @q and start auto suspend for |
3119 | * @dev. Drivers that want to take advantage of request-based runtime PM |
3120 | * should call this function after @dev has been initialized, and its |
3121 | * request queue @q has been allocated, and runtime PM for it can not happen |
3122 | * yet(either due to disabled/forbidden or its usage_count > 0). In most |
3123 | * cases, driver should call this function before any I/O has taken place. |
3124 | * |
3125 | * This function takes care of setting up using auto suspend for the device, |
3126 | * the autosuspend delay is set to -1 to make runtime suspend impossible |
3127 | * until an updated value is either set by user or by driver. Drivers do |
3128 | * not need to touch other autosuspend settings. |
3129 | * |
3130 | * The block layer runtime PM is request based, so only works for drivers |
3131 | * that use request as their IO unit instead of those directly use bio's. |
3132 | */ |
3133 | void blk_pm_runtime_init(struct request_queue *q, struct device *dev) |
3134 | { |
3135 | q->dev = dev; |
3136 | q->rpm_status = RPM_ACTIVE; |
3137 | pm_runtime_set_autosuspend_delay(q->dev, -1); |
3138 | pm_runtime_use_autosuspend(q->dev); |
3139 | } |
3140 | EXPORT_SYMBOL(blk_pm_runtime_init); |
3141 | |
3142 | /** |
3143 | * blk_pre_runtime_suspend - Pre runtime suspend check |
3144 | * @q: the queue of the device |
3145 | * |
3146 | * Description: |
3147 | * This function will check if runtime suspend is allowed for the device |
3148 | * by examining if there are any requests pending in the queue. If there |
3149 | * are requests pending, the device can not be runtime suspended; otherwise, |
3150 | * the queue's status will be updated to SUSPENDING and the driver can |
3151 | * proceed to suspend the device. |
3152 | * |
3153 | * For the not allowed case, we mark last busy for the device so that |
3154 | * runtime PM core will try to autosuspend it some time later. |
3155 | * |
3156 | * This function should be called near the start of the device's |
3157 | * runtime_suspend callback. |
3158 | * |
3159 | * Return: |
3160 | * 0 - OK to runtime suspend the device |
3161 | * -EBUSY - Device should not be runtime suspended |
3162 | */ |
3163 | int blk_pre_runtime_suspend(struct request_queue *q) |
3164 | { |
3165 | int ret = 0; |
3166 | |
3167 | spin_lock_irq(q->queue_lock); |
3168 | if (q->nr_pending) { |
3169 | ret = -EBUSY; |
3170 | pm_runtime_mark_last_busy(q->dev); |
3171 | } else { |
3172 | q->rpm_status = RPM_SUSPENDING; |
3173 | } |
3174 | spin_unlock_irq(q->queue_lock); |
3175 | return ret; |
3176 | } |
3177 | EXPORT_SYMBOL(blk_pre_runtime_suspend); |
3178 | |
3179 | /** |
3180 | * blk_post_runtime_suspend - Post runtime suspend processing |
3181 | * @q: the queue of the device |
3182 | * @err: return value of the device's runtime_suspend function |
3183 | * |
3184 | * Description: |
3185 | * Update the queue's runtime status according to the return value of the |
3186 | * device's runtime suspend function and mark last busy for the device so |
3187 | * that PM core will try to auto suspend the device at a later time. |
3188 | * |
3189 | * This function should be called near the end of the device's |
3190 | * runtime_suspend callback. |
3191 | */ |
3192 | void blk_post_runtime_suspend(struct request_queue *q, int err) |
3193 | { |
3194 | spin_lock_irq(q->queue_lock); |
3195 | if (!err) { |
3196 | q->rpm_status = RPM_SUSPENDED; |
3197 | } else { |
3198 | q->rpm_status = RPM_ACTIVE; |
3199 | pm_runtime_mark_last_busy(q->dev); |
3200 | } |
3201 | spin_unlock_irq(q->queue_lock); |
3202 | } |
3203 | EXPORT_SYMBOL(blk_post_runtime_suspend); |
3204 | |
3205 | /** |
3206 | * blk_pre_runtime_resume - Pre runtime resume processing |
3207 | * @q: the queue of the device |
3208 | * |
3209 | * Description: |
3210 | * Update the queue's runtime status to RESUMING in preparation for the |
3211 | * runtime resume of the device. |
3212 | * |
3213 | * This function should be called near the start of the device's |
3214 | * runtime_resume callback. |
3215 | */ |
3216 | void blk_pre_runtime_resume(struct request_queue *q) |
3217 | { |
3218 | spin_lock_irq(q->queue_lock); |
3219 | q->rpm_status = RPM_RESUMING; |
3220 | spin_unlock_irq(q->queue_lock); |
3221 | } |
3222 | EXPORT_SYMBOL(blk_pre_runtime_resume); |
3223 | |
3224 | /** |
3225 | * blk_post_runtime_resume - Post runtime resume processing |
3226 | * @q: the queue of the device |
3227 | * @err: return value of the device's runtime_resume function |
3228 | * |
3229 | * Description: |
3230 | * Update the queue's runtime status according to the return value of the |
3231 | * device's runtime_resume function. If it is successfully resumed, process |
3232 | * the requests that are queued into the device's queue when it is resuming |
3233 | * and then mark last busy and initiate autosuspend for it. |
3234 | * |
3235 | * This function should be called near the end of the device's |
3236 | * runtime_resume callback. |
3237 | */ |
3238 | void blk_post_runtime_resume(struct request_queue *q, int err) |
3239 | { |
3240 | spin_lock_irq(q->queue_lock); |
3241 | if (!err) { |
3242 | q->rpm_status = RPM_ACTIVE; |
3243 | __blk_run_queue(q); |
3244 | pm_runtime_mark_last_busy(q->dev); |
3245 | pm_request_autosuspend(q->dev); |
3246 | } else { |
3247 | q->rpm_status = RPM_SUSPENDED; |
3248 | } |
3249 | spin_unlock_irq(q->queue_lock); |
3250 | } |
3251 | EXPORT_SYMBOL(blk_post_runtime_resume); |
3252 | #endif |
3253 | |
3254 | int __init blk_dev_init(void) |
3255 | { |
3256 | BUILD_BUG_ON(__REQ_NR_BITS > 8 * |
3257 | sizeof(((struct request *)0)->cmd_flags)); |
3258 | |
3259 | /* used for unplugging and affects IO latency/throughput - HIGHPRI */ |
3260 | kblockd_workqueue = alloc_workqueue("kblockd", |
3261 | WQ_MEM_RECLAIM | WQ_HIGHPRI | |
3262 | WQ_POWER_EFFICIENT, 0); |
3263 | if (!kblockd_workqueue) |
3264 | panic("Failed to create kblockd\n"); |
3265 | |
3266 | request_cachep = kmem_cache_create("blkdev_requests", |
3267 | sizeof(struct request), 0, SLAB_PANIC, NULL); |
3268 | |
3269 | blk_requestq_cachep = kmem_cache_create("blkdev_queue", |
3270 | sizeof(struct request_queue), 0, SLAB_PANIC, NULL); |
3271 | |
3272 | return 0; |
3273 | } |
3274 |
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