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