Root/
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 | |
34 | #define CREATE_TRACE_POINTS |
35 | #include <trace/events/block.h> |
36 | |
37 | #include "blk.h" |
38 | #include "blk-cgroup.h" |
39 | |
40 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); |
41 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); |
42 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); |
43 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug); |
44 | |
45 | DEFINE_IDA(blk_queue_ida); |
46 | |
47 | /* |
48 | * For the allocated request tables |
49 | */ |
50 | static struct kmem_cache *request_cachep; |
51 | |
52 | /* |
53 | * For queue allocation |
54 | */ |
55 | struct kmem_cache *blk_requestq_cachep; |
56 | |
57 | /* |
58 | * Controlling structure to kblockd |
59 | */ |
60 | static struct workqueue_struct *kblockd_workqueue; |
61 | |
62 | static void drive_stat_acct(struct request *rq, int new_io) |
63 | { |
64 | struct hd_struct *part; |
65 | int rw = rq_data_dir(rq); |
66 | int cpu; |
67 | |
68 | if (!blk_do_io_stat(rq)) |
69 | return; |
70 | |
71 | cpu = part_stat_lock(); |
72 | |
73 | if (!new_io) { |
74 | part = rq->part; |
75 | part_stat_inc(cpu, part, merges[rw]); |
76 | } else { |
77 | part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); |
78 | if (!hd_struct_try_get(part)) { |
79 | /* |
80 | * The partition is already being removed, |
81 | * the request will be accounted on the disk only |
82 | * |
83 | * We take a reference on disk->part0 although that |
84 | * partition will never be deleted, so we can treat |
85 | * it as any other partition. |
86 | */ |
87 | part = &rq->rq_disk->part0; |
88 | hd_struct_get(part); |
89 | } |
90 | part_round_stats(cpu, part); |
91 | part_inc_in_flight(part, rw); |
92 | rq->part = part; |
93 | } |
94 | |
95 | part_stat_unlock(); |
96 | } |
97 | |
98 | void blk_queue_congestion_threshold(struct request_queue *q) |
99 | { |
100 | int nr; |
101 | |
102 | nr = q->nr_requests - (q->nr_requests / 8) + 1; |
103 | if (nr > q->nr_requests) |
104 | nr = q->nr_requests; |
105 | q->nr_congestion_on = nr; |
106 | |
107 | nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1; |
108 | if (nr < 1) |
109 | nr = 1; |
110 | q->nr_congestion_off = nr; |
111 | } |
112 | |
113 | /** |
114 | * blk_get_backing_dev_info - get the address of a queue's backing_dev_info |
115 | * @bdev: device |
116 | * |
117 | * Locates the passed device's request queue and returns the address of its |
118 | * backing_dev_info |
119 | * |
120 | * Will return NULL if the request queue cannot be located. |
121 | */ |
122 | struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) |
123 | { |
124 | struct backing_dev_info *ret = NULL; |
125 | struct request_queue *q = bdev_get_queue(bdev); |
126 | |
127 | if (q) |
128 | ret = &q->backing_dev_info; |
129 | return ret; |
130 | } |
131 | EXPORT_SYMBOL(blk_get_backing_dev_info); |
132 | |
133 | void blk_rq_init(struct request_queue *q, struct request *rq) |
134 | { |
135 | memset(rq, 0, sizeof(*rq)); |
136 | |
137 | INIT_LIST_HEAD(&rq->queuelist); |
138 | INIT_LIST_HEAD(&rq->timeout_list); |
139 | rq->cpu = -1; |
140 | rq->q = q; |
141 | rq->__sector = (sector_t) -1; |
142 | INIT_HLIST_NODE(&rq->hash); |
143 | RB_CLEAR_NODE(&rq->rb_node); |
144 | rq->cmd = rq->__cmd; |
145 | rq->cmd_len = BLK_MAX_CDB; |
146 | rq->tag = -1; |
147 | rq->ref_count = 1; |
148 | rq->start_time = jiffies; |
149 | set_start_time_ns(rq); |
150 | rq->part = NULL; |
151 | } |
152 | EXPORT_SYMBOL(blk_rq_init); |
153 | |
154 | static void req_bio_endio(struct request *rq, struct bio *bio, |
155 | unsigned int nbytes, int error) |
156 | { |
157 | if (error) |
158 | clear_bit(BIO_UPTODATE, &bio->bi_flags); |
159 | else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) |
160 | error = -EIO; |
161 | |
162 | if (unlikely(nbytes > bio->bi_size)) { |
163 | printk(KERN_ERR "%s: want %u bytes done, %u left\n", |
164 | __func__, nbytes, bio->bi_size); |
165 | nbytes = bio->bi_size; |
166 | } |
167 | |
168 | if (unlikely(rq->cmd_flags & REQ_QUIET)) |
169 | set_bit(BIO_QUIET, &bio->bi_flags); |
170 | |
171 | bio->bi_size -= nbytes; |
172 | bio->bi_sector += (nbytes >> 9); |
173 | |
174 | if (bio_integrity(bio)) |
175 | bio_integrity_advance(bio, nbytes); |
176 | |
177 | /* don't actually finish bio if it's part of flush sequence */ |
178 | if (bio->bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ)) |
179 | bio_endio(bio, error); |
180 | } |
181 | |
182 | void blk_dump_rq_flags(struct request *rq, char *msg) |
183 | { |
184 | int bit; |
185 | |
186 | printk(KERN_INFO "%s: dev %s: type=%x, flags=%x\n", msg, |
187 | rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type, |
188 | rq->cmd_flags); |
189 | |
190 | printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", |
191 | (unsigned long long)blk_rq_pos(rq), |
192 | blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); |
193 | printk(KERN_INFO " bio %p, biotail %p, buffer %p, len %u\n", |
194 | rq->bio, rq->biotail, rq->buffer, blk_rq_bytes(rq)); |
195 | |
196 | if (rq->cmd_type == REQ_TYPE_BLOCK_PC) { |
197 | printk(KERN_INFO " cdb: "); |
198 | for (bit = 0; bit < BLK_MAX_CDB; bit++) |
199 | printk("%02x ", rq->cmd[bit]); |
200 | printk("\n"); |
201 | } |
202 | } |
203 | EXPORT_SYMBOL(blk_dump_rq_flags); |
204 | |
205 | static void blk_delay_work(struct work_struct *work) |
206 | { |
207 | struct request_queue *q; |
208 | |
209 | q = container_of(work, struct request_queue, delay_work.work); |
210 | spin_lock_irq(q->queue_lock); |
211 | __blk_run_queue(q); |
212 | spin_unlock_irq(q->queue_lock); |
213 | } |
214 | |
215 | /** |
216 | * blk_delay_queue - restart queueing after defined interval |
217 | * @q: The &struct request_queue in question |
218 | * @msecs: Delay in msecs |
219 | * |
220 | * Description: |
221 | * Sometimes queueing needs to be postponed for a little while, to allow |
222 | * resources to come back. This function will make sure that queueing is |
223 | * restarted around the specified time. Queue lock must be held. |
224 | */ |
225 | void blk_delay_queue(struct request_queue *q, unsigned long msecs) |
226 | { |
227 | if (likely(!blk_queue_dead(q))) |
228 | queue_delayed_work(kblockd_workqueue, &q->delay_work, |
229 | msecs_to_jiffies(msecs)); |
230 | } |
231 | EXPORT_SYMBOL(blk_delay_queue); |
232 | |
233 | /** |
234 | * blk_start_queue - restart a previously stopped queue |
235 | * @q: The &struct request_queue in question |
236 | * |
237 | * Description: |
238 | * blk_start_queue() will clear the stop flag on the queue, and call |
239 | * the request_fn for the queue if it was in a stopped state when |
240 | * entered. Also see blk_stop_queue(). Queue lock must be held. |
241 | **/ |
242 | void blk_start_queue(struct request_queue *q) |
243 | { |
244 | WARN_ON(!irqs_disabled()); |
245 | |
246 | queue_flag_clear(QUEUE_FLAG_STOPPED, q); |
247 | __blk_run_queue(q); |
248 | } |
249 | EXPORT_SYMBOL(blk_start_queue); |
250 | |
251 | /** |
252 | * blk_stop_queue - stop a queue |
253 | * @q: The &struct request_queue in question |
254 | * |
255 | * Description: |
256 | * The Linux block layer assumes that a block driver will consume all |
257 | * entries on the request queue when the request_fn strategy is called. |
258 | * Often this will not happen, because of hardware limitations (queue |
259 | * depth settings). If a device driver gets a 'queue full' response, |
260 | * or if it simply chooses not to queue more I/O at one point, it can |
261 | * call this function to prevent the request_fn from being called until |
262 | * the driver has signalled it's ready to go again. This happens by calling |
263 | * blk_start_queue() to restart queue operations. Queue lock must be held. |
264 | **/ |
265 | void blk_stop_queue(struct request_queue *q) |
266 | { |
267 | cancel_delayed_work(&q->delay_work); |
268 | queue_flag_set(QUEUE_FLAG_STOPPED, q); |
269 | } |
270 | EXPORT_SYMBOL(blk_stop_queue); |
271 | |
272 | /** |
273 | * blk_sync_queue - cancel any pending callbacks on a queue |
274 | * @q: the queue |
275 | * |
276 | * Description: |
277 | * The block layer may perform asynchronous callback activity |
278 | * on a queue, such as calling the unplug function after a timeout. |
279 | * A block device may call blk_sync_queue to ensure that any |
280 | * such activity is cancelled, thus allowing it to release resources |
281 | * that the callbacks might use. The caller must already have made sure |
282 | * that its ->make_request_fn will not re-add plugging prior to calling |
283 | * this function. |
284 | * |
285 | * This function does not cancel any asynchronous activity arising |
286 | * out of elevator or throttling code. That would require elevaotor_exit() |
287 | * and blkcg_exit_queue() to be called with queue lock initialized. |
288 | * |
289 | */ |
290 | void blk_sync_queue(struct request_queue *q) |
291 | { |
292 | del_timer_sync(&q->timeout); |
293 | cancel_delayed_work_sync(&q->delay_work); |
294 | } |
295 | EXPORT_SYMBOL(blk_sync_queue); |
296 | |
297 | /** |
298 | * __blk_run_queue_uncond - run a queue whether or not it has been stopped |
299 | * @q: The queue to run |
300 | * |
301 | * Description: |
302 | * Invoke request handling on a queue if there are any pending requests. |
303 | * May be used to restart request handling after a request has completed. |
304 | * This variant runs the queue whether or not the queue has been |
305 | * stopped. Must be called with the queue lock held and interrupts |
306 | * disabled. See also @blk_run_queue. |
307 | */ |
308 | inline void __blk_run_queue_uncond(struct request_queue *q) |
309 | { |
310 | if (unlikely(blk_queue_dead(q))) |
311 | return; |
312 | |
313 | /* |
314 | * Some request_fn implementations, e.g. scsi_request_fn(), unlock |
315 | * the queue lock internally. As a result multiple threads may be |
316 | * running such a request function concurrently. Keep track of the |
317 | * number of active request_fn invocations such that blk_drain_queue() |
318 | * can wait until all these request_fn calls have finished. |
319 | */ |
320 | q->request_fn_active++; |
321 | q->request_fn(q); |
322 | q->request_fn_active--; |
323 | } |
324 | |
325 | /** |
326 | * __blk_run_queue - run a single device queue |
327 | * @q: The queue to run |
328 | * |
329 | * Description: |
330 | * See @blk_run_queue. This variant must be called with the queue lock |
331 | * held and interrupts disabled. |
332 | */ |
333 | void __blk_run_queue(struct request_queue *q) |
334 | { |
335 | if (unlikely(blk_queue_stopped(q))) |
336 | return; |
337 | |
338 | __blk_run_queue_uncond(q); |
339 | } |
340 | EXPORT_SYMBOL(__blk_run_queue); |
341 | |
342 | /** |
343 | * blk_run_queue_async - run a single device queue in workqueue context |
344 | * @q: The queue to run |
345 | * |
346 | * Description: |
347 | * Tells kblockd to perform the equivalent of @blk_run_queue on behalf |
348 | * of us. The caller must hold the queue lock. |
349 | */ |
350 | void blk_run_queue_async(struct request_queue *q) |
351 | { |
352 | if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q))) |
353 | mod_delayed_work(kblockd_workqueue, &q->delay_work, 0); |
354 | } |
355 | EXPORT_SYMBOL(blk_run_queue_async); |
356 | |
357 | /** |
358 | * blk_run_queue - run a single device queue |
359 | * @q: The queue to run |
360 | * |
361 | * Description: |
362 | * Invoke request handling on this queue, if it has pending work to do. |
363 | * May be used to restart queueing when a request has completed. |
364 | */ |
365 | void blk_run_queue(struct request_queue *q) |
366 | { |
367 | unsigned long flags; |
368 | |
369 | spin_lock_irqsave(q->queue_lock, flags); |
370 | __blk_run_queue(q); |
371 | spin_unlock_irqrestore(q->queue_lock, flags); |
372 | } |
373 | EXPORT_SYMBOL(blk_run_queue); |
374 | |
375 | void blk_put_queue(struct request_queue *q) |
376 | { |
377 | kobject_put(&q->kobj); |
378 | } |
379 | EXPORT_SYMBOL(blk_put_queue); |
380 | |
381 | /** |
382 | * __blk_drain_queue - drain requests from request_queue |
383 | * @q: queue to drain |
384 | * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV |
385 | * |
386 | * Drain requests from @q. If @drain_all is set, all requests are drained. |
387 | * If not, only ELVPRIV requests are drained. The caller is responsible |
388 | * for ensuring that no new requests which need to be drained are queued. |
389 | */ |
390 | static void __blk_drain_queue(struct request_queue *q, bool drain_all) |
391 | __releases(q->queue_lock) |
392 | __acquires(q->queue_lock) |
393 | { |
394 | int i; |
395 | |
396 | lockdep_assert_held(q->queue_lock); |
397 | |
398 | while (true) { |
399 | bool drain = false; |
400 | |
401 | /* |
402 | * The caller might be trying to drain @q before its |
403 | * elevator is initialized. |
404 | */ |
405 | if (q->elevator) |
406 | elv_drain_elevator(q); |
407 | |
408 | blkcg_drain_queue(q); |
409 | |
410 | /* |
411 | * This function might be called on a queue which failed |
412 | * driver init after queue creation or is not yet fully |
413 | * active yet. Some drivers (e.g. fd and loop) get unhappy |
414 | * in such cases. Kick queue iff dispatch queue has |
415 | * something on it and @q has request_fn set. |
416 | */ |
417 | if (!list_empty(&q->queue_head) && q->request_fn) |
418 | __blk_run_queue(q); |
419 | |
420 | drain |= q->nr_rqs_elvpriv; |
421 | drain |= q->request_fn_active; |
422 | |
423 | /* |
424 | * Unfortunately, requests are queued at and tracked from |
425 | * multiple places and there's no single counter which can |
426 | * be drained. Check all the queues and counters. |
427 | */ |
428 | if (drain_all) { |
429 | drain |= !list_empty(&q->queue_head); |
430 | for (i = 0; i < 2; i++) { |
431 | drain |= q->nr_rqs[i]; |
432 | drain |= q->in_flight[i]; |
433 | drain |= !list_empty(&q->flush_queue[i]); |
434 | } |
435 | } |
436 | |
437 | if (!drain) |
438 | break; |
439 | |
440 | spin_unlock_irq(q->queue_lock); |
441 | |
442 | msleep(10); |
443 | |
444 | spin_lock_irq(q->queue_lock); |
445 | } |
446 | |
447 | /* |
448 | * With queue marked dead, any woken up waiter will fail the |
449 | * allocation path, so the wakeup chaining is lost and we're |
450 | * left with hung waiters. We need to wake up those waiters. |
451 | */ |
452 | if (q->request_fn) { |
453 | struct request_list *rl; |
454 | |
455 | blk_queue_for_each_rl(rl, q) |
456 | for (i = 0; i < ARRAY_SIZE(rl->wait); i++) |
457 | wake_up_all(&rl->wait[i]); |
458 | } |
459 | } |
460 | |
461 | /** |
462 | * blk_queue_bypass_start - enter queue bypass mode |
463 | * @q: queue of interest |
464 | * |
465 | * In bypass mode, only the dispatch FIFO queue of @q is used. This |
466 | * function makes @q enter bypass mode and drains all requests which were |
467 | * throttled or issued before. On return, it's guaranteed that no request |
468 | * is being throttled or has ELVPRIV set and blk_queue_bypass() %true |
469 | * inside queue or RCU read lock. |
470 | */ |
471 | void blk_queue_bypass_start(struct request_queue *q) |
472 | { |
473 | bool drain; |
474 | |
475 | spin_lock_irq(q->queue_lock); |
476 | drain = !q->bypass_depth++; |
477 | queue_flag_set(QUEUE_FLAG_BYPASS, q); |
478 | spin_unlock_irq(q->queue_lock); |
479 | |
480 | if (drain) { |
481 | spin_lock_irq(q->queue_lock); |
482 | __blk_drain_queue(q, false); |
483 | spin_unlock_irq(q->queue_lock); |
484 | |
485 | /* ensure blk_queue_bypass() is %true inside RCU read lock */ |
486 | synchronize_rcu(); |
487 | } |
488 | } |
489 | EXPORT_SYMBOL_GPL(blk_queue_bypass_start); |
490 | |
491 | /** |
492 | * blk_queue_bypass_end - leave queue bypass mode |
493 | * @q: queue of interest |
494 | * |
495 | * Leave bypass mode and restore the normal queueing behavior. |
496 | */ |
497 | void blk_queue_bypass_end(struct request_queue *q) |
498 | { |
499 | spin_lock_irq(q->queue_lock); |
500 | if (!--q->bypass_depth) |
501 | queue_flag_clear(QUEUE_FLAG_BYPASS, q); |
502 | WARN_ON_ONCE(q->bypass_depth < 0); |
503 | spin_unlock_irq(q->queue_lock); |
504 | } |
505 | EXPORT_SYMBOL_GPL(blk_queue_bypass_end); |
506 | |
507 | /** |
508 | * blk_cleanup_queue - shutdown a request queue |
509 | * @q: request queue to shutdown |
510 | * |
511 | * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and |
512 | * put it. All future requests will be failed immediately with -ENODEV. |
513 | */ |
514 | void blk_cleanup_queue(struct request_queue *q) |
515 | { |
516 | spinlock_t *lock = q->queue_lock; |
517 | |
518 | /* mark @q DYING, no new request or merges will be allowed afterwards */ |
519 | mutex_lock(&q->sysfs_lock); |
520 | queue_flag_set_unlocked(QUEUE_FLAG_DYING, q); |
521 | spin_lock_irq(lock); |
522 | |
523 | /* |
524 | * A dying queue is permanently in bypass mode till released. Note |
525 | * that, unlike blk_queue_bypass_start(), we aren't performing |
526 | * synchronize_rcu() after entering bypass mode to avoid the delay |
527 | * as some drivers create and destroy a lot of queues while |
528 | * probing. This is still safe because blk_release_queue() will be |
529 | * called only after the queue refcnt drops to zero and nothing, |
530 | * RCU or not, would be traversing the queue by then. |
531 | */ |
532 | q->bypass_depth++; |
533 | queue_flag_set(QUEUE_FLAG_BYPASS, q); |
534 | |
535 | queue_flag_set(QUEUE_FLAG_NOMERGES, q); |
536 | queue_flag_set(QUEUE_FLAG_NOXMERGES, q); |
537 | queue_flag_set(QUEUE_FLAG_DYING, q); |
538 | spin_unlock_irq(lock); |
539 | mutex_unlock(&q->sysfs_lock); |
540 | |
541 | /* |
542 | * Drain all requests queued before DYING marking. Set DEAD flag to |
543 | * prevent that q->request_fn() gets invoked after draining finished. |
544 | */ |
545 | spin_lock_irq(lock); |
546 | __blk_drain_queue(q, true); |
547 | queue_flag_set(QUEUE_FLAG_DEAD, q); |
548 | spin_unlock_irq(lock); |
549 | |
550 | /* @q won't process any more request, flush async actions */ |
551 | del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer); |
552 | blk_sync_queue(q); |
553 | |
554 | spin_lock_irq(lock); |
555 | if (q->queue_lock != &q->__queue_lock) |
556 | q->queue_lock = &q->__queue_lock; |
557 | spin_unlock_irq(lock); |
558 | |
559 | /* @q is and will stay empty, shutdown and put */ |
560 | blk_put_queue(q); |
561 | } |
562 | EXPORT_SYMBOL(blk_cleanup_queue); |
563 | |
564 | int blk_init_rl(struct request_list *rl, struct request_queue *q, |
565 | gfp_t gfp_mask) |
566 | { |
567 | if (unlikely(rl->rq_pool)) |
568 | return 0; |
569 | |
570 | rl->q = q; |
571 | rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0; |
572 | rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0; |
573 | init_waitqueue_head(&rl->wait[BLK_RW_SYNC]); |
574 | init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]); |
575 | |
576 | rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
577 | mempool_free_slab, request_cachep, |
578 | gfp_mask, q->node); |
579 | if (!rl->rq_pool) |
580 | return -ENOMEM; |
581 | |
582 | return 0; |
583 | } |
584 | |
585 | void blk_exit_rl(struct request_list *rl) |
586 | { |
587 | if (rl->rq_pool) |
588 | mempool_destroy(rl->rq_pool); |
589 | } |
590 | |
591 | struct request_queue *blk_alloc_queue(gfp_t gfp_mask) |
592 | { |
593 | return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE); |
594 | } |
595 | EXPORT_SYMBOL(blk_alloc_queue); |
596 | |
597 | struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) |
598 | { |
599 | struct request_queue *q; |
600 | int err; |
601 | |
602 | q = kmem_cache_alloc_node(blk_requestq_cachep, |
603 | gfp_mask | __GFP_ZERO, node_id); |
604 | if (!q) |
605 | return NULL; |
606 | |
607 | q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask); |
608 | if (q->id < 0) |
609 | goto fail_q; |
610 | |
611 | q->backing_dev_info.ra_pages = |
612 | (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; |
613 | q->backing_dev_info.state = 0; |
614 | q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; |
615 | q->backing_dev_info.name = "block"; |
616 | q->node = node_id; |
617 | |
618 | err = bdi_init(&q->backing_dev_info); |
619 | if (err) |
620 | goto fail_id; |
621 | |
622 | setup_timer(&q->backing_dev_info.laptop_mode_wb_timer, |
623 | laptop_mode_timer_fn, (unsigned long) q); |
624 | setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q); |
625 | INIT_LIST_HEAD(&q->queue_head); |
626 | INIT_LIST_HEAD(&q->timeout_list); |
627 | INIT_LIST_HEAD(&q->icq_list); |
628 | #ifdef CONFIG_BLK_CGROUP |
629 | INIT_LIST_HEAD(&q->blkg_list); |
630 | #endif |
631 | INIT_LIST_HEAD(&q->flush_queue[0]); |
632 | INIT_LIST_HEAD(&q->flush_queue[1]); |
633 | INIT_LIST_HEAD(&q->flush_data_in_flight); |
634 | INIT_DELAYED_WORK(&q->delay_work, blk_delay_work); |
635 | |
636 | kobject_init(&q->kobj, &blk_queue_ktype); |
637 | |
638 | mutex_init(&q->sysfs_lock); |
639 | spin_lock_init(&q->__queue_lock); |
640 | |
641 | /* |
642 | * By default initialize queue_lock to internal lock and driver can |
643 | * override it later if need be. |
644 | */ |
645 | q->queue_lock = &q->__queue_lock; |
646 | |
647 | /* |
648 | * A queue starts its life with bypass turned on to avoid |
649 | * unnecessary bypass on/off overhead and nasty surprises during |
650 | * init. The initial bypass will be finished when the queue is |
651 | * registered by blk_register_queue(). |
652 | */ |
653 | q->bypass_depth = 1; |
654 | __set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags); |
655 | |
656 | if (blkcg_init_queue(q)) |
657 | goto fail_id; |
658 | |
659 | return q; |
660 | |
661 | fail_id: |
662 | ida_simple_remove(&blk_queue_ida, q->id); |
663 | fail_q: |
664 | kmem_cache_free(blk_requestq_cachep, q); |
665 | return NULL; |
666 | } |
667 | EXPORT_SYMBOL(blk_alloc_queue_node); |
668 | |
669 | /** |
670 | * blk_init_queue - prepare a request queue for use with a block device |
671 | * @rfn: The function to be called to process requests that have been |
672 | * placed on the queue. |
673 | * @lock: Request queue spin lock |
674 | * |
675 | * Description: |
676 | * If a block device wishes to use the standard request handling procedures, |
677 | * which sorts requests and coalesces adjacent requests, then it must |
678 | * call blk_init_queue(). The function @rfn will be called when there |
679 | * are requests on the queue that need to be processed. If the device |
680 | * supports plugging, then @rfn may not be called immediately when requests |
681 | * are available on the queue, but may be called at some time later instead. |
682 | * Plugged queues are generally unplugged when a buffer belonging to one |
683 | * of the requests on the queue is needed, or due to memory pressure. |
684 | * |
685 | * @rfn is not required, or even expected, to remove all requests off the |
686 | * queue, but only as many as it can handle at a time. If it does leave |
687 | * requests on the queue, it is responsible for arranging that the requests |
688 | * get dealt with eventually. |
689 | * |
690 | * The queue spin lock must be held while manipulating the requests on the |
691 | * request queue; this lock will be taken also from interrupt context, so irq |
692 | * disabling is needed for it. |
693 | * |
694 | * Function returns a pointer to the initialized request queue, or %NULL if |
695 | * it didn't succeed. |
696 | * |
697 | * Note: |
698 | * blk_init_queue() must be paired with a blk_cleanup_queue() call |
699 | * when the block device is deactivated (such as at module unload). |
700 | **/ |
701 | |
702 | struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) |
703 | { |
704 | return blk_init_queue_node(rfn, lock, NUMA_NO_NODE); |
705 | } |
706 | EXPORT_SYMBOL(blk_init_queue); |
707 | |
708 | struct request_queue * |
709 | blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) |
710 | { |
711 | struct request_queue *uninit_q, *q; |
712 | |
713 | uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id); |
714 | if (!uninit_q) |
715 | return NULL; |
716 | |
717 | q = blk_init_allocated_queue(uninit_q, rfn, lock); |
718 | if (!q) |
719 | blk_cleanup_queue(uninit_q); |
720 | |
721 | return q; |
722 | } |
723 | EXPORT_SYMBOL(blk_init_queue_node); |
724 | |
725 | struct request_queue * |
726 | blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn, |
727 | spinlock_t *lock) |
728 | { |
729 | if (!q) |
730 | return NULL; |
731 | |
732 | if (blk_init_rl(&q->root_rl, q, GFP_KERNEL)) |
733 | return NULL; |
734 | |
735 | q->request_fn = rfn; |
736 | q->prep_rq_fn = NULL; |
737 | q->unprep_rq_fn = NULL; |
738 | q->queue_flags |= QUEUE_FLAG_DEFAULT; |
739 | |
740 | /* Override internal queue lock with supplied lock pointer */ |
741 | if (lock) |
742 | q->queue_lock = lock; |
743 | |
744 | /* |
745 | * This also sets hw/phys segments, boundary and size |
746 | */ |
747 | blk_queue_make_request(q, blk_queue_bio); |
748 | |
749 | q->sg_reserved_size = INT_MAX; |
750 | |
751 | /* init elevator */ |
752 | if (elevator_init(q, NULL)) |
753 | return NULL; |
754 | return q; |
755 | } |
756 | EXPORT_SYMBOL(blk_init_allocated_queue); |
757 | |
758 | bool blk_get_queue(struct request_queue *q) |
759 | { |
760 | if (likely(!blk_queue_dying(q))) { |
761 | __blk_get_queue(q); |
762 | return true; |
763 | } |
764 | |
765 | return false; |
766 | } |
767 | EXPORT_SYMBOL(blk_get_queue); |
768 | |
769 | static inline void blk_free_request(struct request_list *rl, struct request *rq) |
770 | { |
771 | if (rq->cmd_flags & REQ_ELVPRIV) { |
772 | elv_put_request(rl->q, rq); |
773 | if (rq->elv.icq) |
774 | put_io_context(rq->elv.icq->ioc); |
775 | } |
776 | |
777 | mempool_free(rq, rl->rq_pool); |
778 | } |
779 | |
780 | /* |
781 | * ioc_batching returns true if the ioc is a valid batching request and |
782 | * should be given priority access to a request. |
783 | */ |
784 | static inline int ioc_batching(struct request_queue *q, struct io_context *ioc) |
785 | { |
786 | if (!ioc) |
787 | return 0; |
788 | |
789 | /* |
790 | * Make sure the process is able to allocate at least 1 request |
791 | * even if the batch times out, otherwise we could theoretically |
792 | * lose wakeups. |
793 | */ |
794 | return ioc->nr_batch_requests == q->nr_batching || |
795 | (ioc->nr_batch_requests > 0 |
796 | && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); |
797 | } |
798 | |
799 | /* |
800 | * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This |
801 | * will cause the process to be a "batcher" on all queues in the system. This |
802 | * is the behaviour we want though - once it gets a wakeup it should be given |
803 | * a nice run. |
804 | */ |
805 | static void ioc_set_batching(struct request_queue *q, struct io_context *ioc) |
806 | { |
807 | if (!ioc || ioc_batching(q, ioc)) |
808 | return; |
809 | |
810 | ioc->nr_batch_requests = q->nr_batching; |
811 | ioc->last_waited = jiffies; |
812 | } |
813 | |
814 | static void __freed_request(struct request_list *rl, int sync) |
815 | { |
816 | struct request_queue *q = rl->q; |
817 | |
818 | /* |
819 | * bdi isn't aware of blkcg yet. As all async IOs end up root |
820 | * blkcg anyway, just use root blkcg state. |
821 | */ |
822 | if (rl == &q->root_rl && |
823 | rl->count[sync] < queue_congestion_off_threshold(q)) |
824 | blk_clear_queue_congested(q, sync); |
825 | |
826 | if (rl->count[sync] + 1 <= q->nr_requests) { |
827 | if (waitqueue_active(&rl->wait[sync])) |
828 | wake_up(&rl->wait[sync]); |
829 | |
830 | blk_clear_rl_full(rl, sync); |
831 | } |
832 | } |
833 | |
834 | /* |
835 | * A request has just been released. Account for it, update the full and |
836 | * congestion status, wake up any waiters. Called under q->queue_lock. |
837 | */ |
838 | static void freed_request(struct request_list *rl, unsigned int flags) |
839 | { |
840 | struct request_queue *q = rl->q; |
841 | int sync = rw_is_sync(flags); |
842 | |
843 | q->nr_rqs[sync]--; |
844 | rl->count[sync]--; |
845 | if (flags & REQ_ELVPRIV) |
846 | q->nr_rqs_elvpriv--; |
847 | |
848 | __freed_request(rl, sync); |
849 | |
850 | if (unlikely(rl->starved[sync ^ 1])) |
851 | __freed_request(rl, sync ^ 1); |
852 | } |
853 | |
854 | /* |
855 | * Determine if elevator data should be initialized when allocating the |
856 | * request associated with @bio. |
857 | */ |
858 | static bool blk_rq_should_init_elevator(struct bio *bio) |
859 | { |
860 | if (!bio) |
861 | return true; |
862 | |
863 | /* |
864 | * Flush requests do not use the elevator so skip initialization. |
865 | * This allows a request to share the flush and elevator data. |
866 | */ |
867 | if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) |
868 | return false; |
869 | |
870 | return true; |
871 | } |
872 | |
873 | /** |
874 | * rq_ioc - determine io_context for request allocation |
875 | * @bio: request being allocated is for this bio (can be %NULL) |
876 | * |
877 | * Determine io_context to use for request allocation for @bio. May return |
878 | * %NULL if %current->io_context doesn't exist. |
879 | */ |
880 | static struct io_context *rq_ioc(struct bio *bio) |
881 | { |
882 | #ifdef CONFIG_BLK_CGROUP |
883 | if (bio && bio->bi_ioc) |
884 | return bio->bi_ioc; |
885 | #endif |
886 | return current->io_context; |
887 | } |
888 | |
889 | /** |
890 | * __get_request - get a free request |
891 | * @rl: request list to allocate from |
892 | * @rw_flags: RW and SYNC flags |
893 | * @bio: bio to allocate request for (can be %NULL) |
894 | * @gfp_mask: allocation mask |
895 | * |
896 | * Get a free request from @q. This function may fail under memory |
897 | * pressure or if @q is dead. |
898 | * |
899 | * Must be callled with @q->queue_lock held and, |
900 | * Returns %NULL on failure, with @q->queue_lock held. |
901 | * Returns !%NULL on success, with @q->queue_lock *not held*. |
902 | */ |
903 | static struct request *__get_request(struct request_list *rl, int rw_flags, |
904 | struct bio *bio, gfp_t gfp_mask) |
905 | { |
906 | struct request_queue *q = rl->q; |
907 | struct request *rq; |
908 | struct elevator_type *et = q->elevator->type; |
909 | struct io_context *ioc = rq_ioc(bio); |
910 | struct io_cq *icq = NULL; |
911 | const bool is_sync = rw_is_sync(rw_flags) != 0; |
912 | int may_queue; |
913 | |
914 | if (unlikely(blk_queue_dying(q))) |
915 | return NULL; |
916 | |
917 | may_queue = elv_may_queue(q, rw_flags); |
918 | if (may_queue == ELV_MQUEUE_NO) |
919 | goto rq_starved; |
920 | |
921 | if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) { |
922 | if (rl->count[is_sync]+1 >= q->nr_requests) { |
923 | /* |
924 | * The queue will fill after this allocation, so set |
925 | * it as full, and mark this process as "batching". |
926 | * This process will be allowed to complete a batch of |
927 | * requests, others will be blocked. |
928 | */ |
929 | if (!blk_rl_full(rl, is_sync)) { |
930 | ioc_set_batching(q, ioc); |
931 | blk_set_rl_full(rl, is_sync); |
932 | } else { |
933 | if (may_queue != ELV_MQUEUE_MUST |
934 | && !ioc_batching(q, ioc)) { |
935 | /* |
936 | * The queue is full and the allocating |
937 | * process is not a "batcher", and not |
938 | * exempted by the IO scheduler |
939 | */ |
940 | return NULL; |
941 | } |
942 | } |
943 | } |
944 | /* |
945 | * bdi isn't aware of blkcg yet. As all async IOs end up |
946 | * root blkcg anyway, just use root blkcg state. |
947 | */ |
948 | if (rl == &q->root_rl) |
949 | blk_set_queue_congested(q, is_sync); |
950 | } |
951 | |
952 | /* |
953 | * Only allow batching queuers to allocate up to 50% over the defined |
954 | * limit of requests, otherwise we could have thousands of requests |
955 | * allocated with any setting of ->nr_requests |
956 | */ |
957 | if (rl->count[is_sync] >= (3 * q->nr_requests / 2)) |
958 | return NULL; |
959 | |
960 | q->nr_rqs[is_sync]++; |
961 | rl->count[is_sync]++; |
962 | rl->starved[is_sync] = 0; |
963 | |
964 | /* |
965 | * Decide whether the new request will be managed by elevator. If |
966 | * so, mark @rw_flags and increment elvpriv. Non-zero elvpriv will |
967 | * prevent the current elevator from being destroyed until the new |
968 | * request is freed. This guarantees icq's won't be destroyed and |
969 | * makes creating new ones safe. |
970 | * |
971 | * Also, lookup icq while holding queue_lock. If it doesn't exist, |
972 | * it will be created after releasing queue_lock. |
973 | */ |
974 | if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) { |
975 | rw_flags |= REQ_ELVPRIV; |
976 | q->nr_rqs_elvpriv++; |
977 | if (et->icq_cache && ioc) |
978 | icq = ioc_lookup_icq(ioc, q); |
979 | } |
980 | |
981 | if (blk_queue_io_stat(q)) |
982 | rw_flags |= REQ_IO_STAT; |
983 | spin_unlock_irq(q->queue_lock); |
984 | |
985 | /* allocate and init request */ |
986 | rq = mempool_alloc(rl->rq_pool, gfp_mask); |
987 | if (!rq) |
988 | goto fail_alloc; |
989 | |
990 | blk_rq_init(q, rq); |
991 | blk_rq_set_rl(rq, rl); |
992 | rq->cmd_flags = rw_flags | REQ_ALLOCED; |
993 | |
994 | /* init elvpriv */ |
995 | if (rw_flags & REQ_ELVPRIV) { |
996 | if (unlikely(et->icq_cache && !icq)) { |
997 | if (ioc) |
998 | icq = ioc_create_icq(ioc, q, gfp_mask); |
999 | if (!icq) |
1000 | goto fail_elvpriv; |
1001 | } |
1002 | |
1003 | rq->elv.icq = icq; |
1004 | if (unlikely(elv_set_request(q, rq, bio, gfp_mask))) |
1005 | goto fail_elvpriv; |
1006 | |
1007 | /* @rq->elv.icq holds io_context until @rq is freed */ |
1008 | if (icq) |
1009 | get_io_context(icq->ioc); |
1010 | } |
1011 | out: |
1012 | /* |
1013 | * ioc may be NULL here, and ioc_batching will be false. That's |
1014 | * OK, if the queue is under the request limit then requests need |
1015 | * not count toward the nr_batch_requests limit. There will always |
1016 | * be some limit enforced by BLK_BATCH_TIME. |
1017 | */ |
1018 | if (ioc_batching(q, ioc)) |
1019 | ioc->nr_batch_requests--; |
1020 | |
1021 | trace_block_getrq(q, bio, rw_flags & 1); |
1022 | return rq; |
1023 | |
1024 | fail_elvpriv: |
1025 | /* |
1026 | * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed |
1027 | * and may fail indefinitely under memory pressure and thus |
1028 | * shouldn't stall IO. Treat this request as !elvpriv. This will |
1029 | * disturb iosched and blkcg but weird is bettern than dead. |
1030 | */ |
1031 | printk_ratelimited(KERN_WARNING "%s: request aux data allocation failed, iosched may be disturbed\n", |
1032 | dev_name(q->backing_dev_info.dev)); |
1033 | |
1034 | rq->cmd_flags &= ~REQ_ELVPRIV; |
1035 | rq->elv.icq = NULL; |
1036 | |
1037 | spin_lock_irq(q->queue_lock); |
1038 | q->nr_rqs_elvpriv--; |
1039 | spin_unlock_irq(q->queue_lock); |
1040 | goto out; |
1041 | |
1042 | fail_alloc: |
1043 | /* |
1044 | * Allocation failed presumably due to memory. Undo anything we |
1045 | * might have messed up. |
1046 | * |
1047 | * Allocating task should really be put onto the front of the wait |
1048 | * queue, but this is pretty rare. |
1049 | */ |
1050 | spin_lock_irq(q->queue_lock); |
1051 | freed_request(rl, rw_flags); |
1052 | |
1053 | /* |
1054 | * in the very unlikely event that allocation failed and no |
1055 | * requests for this direction was pending, mark us starved so that |
1056 | * freeing of a request in the other direction will notice |
1057 | * us. another possible fix would be to split the rq mempool into |
1058 | * READ and WRITE |
1059 | */ |
1060 | rq_starved: |
1061 | if (unlikely(rl->count[is_sync] == 0)) |
1062 | rl->starved[is_sync] = 1; |
1063 | return NULL; |
1064 | } |
1065 | |
1066 | /** |
1067 | * get_request - get a free request |
1068 | * @q: request_queue to allocate request from |
1069 | * @rw_flags: RW and SYNC flags |
1070 | * @bio: bio to allocate request for (can be %NULL) |
1071 | * @gfp_mask: allocation mask |
1072 | * |
1073 | * Get a free request from @q. If %__GFP_WAIT is set in @gfp_mask, this |
1074 | * function keeps retrying under memory pressure and fails iff @q is dead. |
1075 | * |
1076 | * Must be callled with @q->queue_lock held and, |
1077 | * Returns %NULL on failure, with @q->queue_lock held. |
1078 | * Returns !%NULL on success, with @q->queue_lock *not held*. |
1079 | */ |
1080 | static struct request *get_request(struct request_queue *q, int rw_flags, |
1081 | struct bio *bio, gfp_t gfp_mask) |
1082 | { |
1083 | const bool is_sync = rw_is_sync(rw_flags) != 0; |
1084 | DEFINE_WAIT(wait); |
1085 | struct request_list *rl; |
1086 | struct request *rq; |
1087 | |
1088 | rl = blk_get_rl(q, bio); /* transferred to @rq on success */ |
1089 | retry: |
1090 | rq = __get_request(rl, rw_flags, bio, gfp_mask); |
1091 | if (rq) |
1092 | return rq; |
1093 | |
1094 | if (!(gfp_mask & __GFP_WAIT) || unlikely(blk_queue_dying(q))) { |
1095 | blk_put_rl(rl); |
1096 | return NULL; |
1097 | } |
1098 | |
1099 | /* wait on @rl and retry */ |
1100 | prepare_to_wait_exclusive(&rl->wait[is_sync], &wait, |
1101 | TASK_UNINTERRUPTIBLE); |
1102 | |
1103 | trace_block_sleeprq(q, bio, rw_flags & 1); |
1104 | |
1105 | spin_unlock_irq(q->queue_lock); |
1106 | io_schedule(); |
1107 | |
1108 | /* |
1109 | * After sleeping, we become a "batching" process and will be able |
1110 | * to allocate at least one request, and up to a big batch of them |
1111 | * for a small period time. See ioc_batching, ioc_set_batching |
1112 | */ |
1113 | ioc_set_batching(q, current->io_context); |
1114 | |
1115 | spin_lock_irq(q->queue_lock); |
1116 | finish_wait(&rl->wait[is_sync], &wait); |
1117 | |
1118 | goto retry; |
1119 | } |
1120 | |
1121 | struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask) |
1122 | { |
1123 | struct request *rq; |
1124 | |
1125 | BUG_ON(rw != READ && rw != WRITE); |
1126 | |
1127 | /* create ioc upfront */ |
1128 | create_io_context(gfp_mask, q->node); |
1129 | |
1130 | spin_lock_irq(q->queue_lock); |
1131 | rq = get_request(q, rw, NULL, gfp_mask); |
1132 | if (!rq) |
1133 | spin_unlock_irq(q->queue_lock); |
1134 | /* q->queue_lock is unlocked at this point */ |
1135 | |
1136 | return rq; |
1137 | } |
1138 | EXPORT_SYMBOL(blk_get_request); |
1139 | |
1140 | /** |
1141 | * blk_make_request - given a bio, allocate a corresponding struct request. |
1142 | * @q: target request queue |
1143 | * @bio: The bio describing the memory mappings that will be submitted for IO. |
1144 | * It may be a chained-bio properly constructed by block/bio layer. |
1145 | * @gfp_mask: gfp flags to be used for memory allocation |
1146 | * |
1147 | * blk_make_request is the parallel of generic_make_request for BLOCK_PC |
1148 | * type commands. Where the struct request needs to be farther initialized by |
1149 | * the caller. It is passed a &struct bio, which describes the memory info of |
1150 | * the I/O transfer. |
1151 | * |
1152 | * The caller of blk_make_request must make sure that bi_io_vec |
1153 | * are set to describe the memory buffers. That bio_data_dir() will return |
1154 | * the needed direction of the request. (And all bio's in the passed bio-chain |
1155 | * are properly set accordingly) |
1156 | * |
1157 | * If called under none-sleepable conditions, mapped bio buffers must not |
1158 | * need bouncing, by calling the appropriate masked or flagged allocator, |
1159 | * suitable for the target device. Otherwise the call to blk_queue_bounce will |
1160 | * BUG. |
1161 | * |
1162 | * WARNING: When allocating/cloning a bio-chain, careful consideration should be |
1163 | * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for |
1164 | * anything but the first bio in the chain. Otherwise you risk waiting for IO |
1165 | * completion of a bio that hasn't been submitted yet, thus resulting in a |
1166 | * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead |
1167 | * of bio_alloc(), as that avoids the mempool deadlock. |
1168 | * If possible a big IO should be split into smaller parts when allocation |
1169 | * fails. Partial allocation should not be an error, or you risk a live-lock. |
1170 | */ |
1171 | struct request *blk_make_request(struct request_queue *q, struct bio *bio, |
1172 | gfp_t gfp_mask) |
1173 | { |
1174 | struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask); |
1175 | |
1176 | if (unlikely(!rq)) |
1177 | return ERR_PTR(-ENOMEM); |
1178 | |
1179 | for_each_bio(bio) { |
1180 | struct bio *bounce_bio = bio; |
1181 | int ret; |
1182 | |
1183 | blk_queue_bounce(q, &bounce_bio); |
1184 | ret = blk_rq_append_bio(q, rq, bounce_bio); |
1185 | if (unlikely(ret)) { |
1186 | blk_put_request(rq); |
1187 | return ERR_PTR(ret); |
1188 | } |
1189 | } |
1190 | |
1191 | return rq; |
1192 | } |
1193 | EXPORT_SYMBOL(blk_make_request); |
1194 | |
1195 | /** |
1196 | * blk_requeue_request - put a request back on queue |
1197 | * @q: request queue where request should be inserted |
1198 | * @rq: request to be inserted |
1199 | * |
1200 | * Description: |
1201 | * Drivers often keep queueing requests until the hardware cannot accept |
1202 | * more, when that condition happens we need to put the request back |
1203 | * on the queue. Must be called with queue lock held. |
1204 | */ |
1205 | void blk_requeue_request(struct request_queue *q, struct request *rq) |
1206 | { |
1207 | blk_delete_timer(rq); |
1208 | blk_clear_rq_complete(rq); |
1209 | trace_block_rq_requeue(q, rq); |
1210 | |
1211 | if (blk_rq_tagged(rq)) |
1212 | blk_queue_end_tag(q, rq); |
1213 | |
1214 | BUG_ON(blk_queued_rq(rq)); |
1215 | |
1216 | elv_requeue_request(q, rq); |
1217 | } |
1218 | EXPORT_SYMBOL(blk_requeue_request); |
1219 | |
1220 | static void add_acct_request(struct request_queue *q, struct request *rq, |
1221 | int where) |
1222 | { |
1223 | drive_stat_acct(rq, 1); |
1224 | __elv_add_request(q, rq, where); |
1225 | } |
1226 | |
1227 | static void part_round_stats_single(int cpu, struct hd_struct *part, |
1228 | unsigned long now) |
1229 | { |
1230 | if (now == part->stamp) |
1231 | return; |
1232 | |
1233 | if (part_in_flight(part)) { |
1234 | __part_stat_add(cpu, part, time_in_queue, |
1235 | part_in_flight(part) * (now - part->stamp)); |
1236 | __part_stat_add(cpu, part, io_ticks, (now - part->stamp)); |
1237 | } |
1238 | part->stamp = now; |
1239 | } |
1240 | |
1241 | /** |
1242 | * part_round_stats() - Round off the performance stats on a struct disk_stats. |
1243 | * @cpu: cpu number for stats access |
1244 | * @part: target partition |
1245 | * |
1246 | * The average IO queue length and utilisation statistics are maintained |
1247 | * by observing the current state of the queue length and the amount of |
1248 | * time it has been in this state for. |
1249 | * |
1250 | * Normally, that accounting is done on IO completion, but that can result |
1251 | * in more than a second's worth of IO being accounted for within any one |
1252 | * second, leading to >100% utilisation. To deal with that, we call this |
1253 | * function to do a round-off before returning the results when reading |
1254 | * /proc/diskstats. This accounts immediately for all queue usage up to |
1255 | * the current jiffies and restarts the counters again. |
1256 | */ |
1257 | void part_round_stats(int cpu, struct hd_struct *part) |
1258 | { |
1259 | unsigned long now = jiffies; |
1260 | |
1261 | if (part->partno) |
1262 | part_round_stats_single(cpu, &part_to_disk(part)->part0, now); |
1263 | part_round_stats_single(cpu, part, now); |
1264 | } |
1265 | EXPORT_SYMBOL_GPL(part_round_stats); |
1266 | |
1267 | /* |
1268 | * queue lock must be held |
1269 | */ |
1270 | void __blk_put_request(struct request_queue *q, struct request *req) |
1271 | { |
1272 | if (unlikely(!q)) |
1273 | return; |
1274 | if (unlikely(--req->ref_count)) |
1275 | return; |
1276 | |
1277 | elv_completed_request(q, req); |
1278 | |
1279 | /* this is a bio leak */ |
1280 | WARN_ON(req->bio != NULL); |
1281 | |
1282 | /* |
1283 | * Request may not have originated from ll_rw_blk. if not, |
1284 | * it didn't come out of our reserved rq pools |
1285 | */ |
1286 | if (req->cmd_flags & REQ_ALLOCED) { |
1287 | unsigned int flags = req->cmd_flags; |
1288 | struct request_list *rl = blk_rq_rl(req); |
1289 | |
1290 | BUG_ON(!list_empty(&req->queuelist)); |
1291 | BUG_ON(!hlist_unhashed(&req->hash)); |
1292 | |
1293 | blk_free_request(rl, req); |
1294 | freed_request(rl, flags); |
1295 | blk_put_rl(rl); |
1296 | } |
1297 | } |
1298 | EXPORT_SYMBOL_GPL(__blk_put_request); |
1299 | |
1300 | void blk_put_request(struct request *req) |
1301 | { |
1302 | unsigned long flags; |
1303 | struct request_queue *q = req->q; |
1304 | |
1305 | spin_lock_irqsave(q->queue_lock, flags); |
1306 | __blk_put_request(q, req); |
1307 | spin_unlock_irqrestore(q->queue_lock, flags); |
1308 | } |
1309 | EXPORT_SYMBOL(blk_put_request); |
1310 | |
1311 | /** |
1312 | * blk_add_request_payload - add a payload to a request |
1313 | * @rq: request to update |
1314 | * @page: page backing the payload |
1315 | * @len: length of the payload. |
1316 | * |
1317 | * This allows to later add a payload to an already submitted request by |
1318 | * a block driver. The driver needs to take care of freeing the payload |
1319 | * itself. |
1320 | * |
1321 | * Note that this is a quite horrible hack and nothing but handling of |
1322 | * discard requests should ever use it. |
1323 | */ |
1324 | void blk_add_request_payload(struct request *rq, struct page *page, |
1325 | unsigned int len) |
1326 | { |
1327 | struct bio *bio = rq->bio; |
1328 | |
1329 | bio->bi_io_vec->bv_page = page; |
1330 | bio->bi_io_vec->bv_offset = 0; |
1331 | bio->bi_io_vec->bv_len = len; |
1332 | |
1333 | bio->bi_size = len; |
1334 | bio->bi_vcnt = 1; |
1335 | bio->bi_phys_segments = 1; |
1336 | |
1337 | rq->__data_len = rq->resid_len = len; |
1338 | rq->nr_phys_segments = 1; |
1339 | rq->buffer = bio_data(bio); |
1340 | } |
1341 | EXPORT_SYMBOL_GPL(blk_add_request_payload); |
1342 | |
1343 | static bool bio_attempt_back_merge(struct request_queue *q, struct request *req, |
1344 | struct bio *bio) |
1345 | { |
1346 | const int ff = bio->bi_rw & REQ_FAILFAST_MASK; |
1347 | |
1348 | if (!ll_back_merge_fn(q, req, bio)) |
1349 | return false; |
1350 | |
1351 | trace_block_bio_backmerge(q, req, bio); |
1352 | |
1353 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) |
1354 | blk_rq_set_mixed_merge(req); |
1355 | |
1356 | req->biotail->bi_next = bio; |
1357 | req->biotail = bio; |
1358 | req->__data_len += bio->bi_size; |
1359 | req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); |
1360 | |
1361 | drive_stat_acct(req, 0); |
1362 | return true; |
1363 | } |
1364 | |
1365 | static bool bio_attempt_front_merge(struct request_queue *q, |
1366 | struct request *req, struct bio *bio) |
1367 | { |
1368 | const int ff = bio->bi_rw & REQ_FAILFAST_MASK; |
1369 | |
1370 | if (!ll_front_merge_fn(q, req, bio)) |
1371 | return false; |
1372 | |
1373 | trace_block_bio_frontmerge(q, req, bio); |
1374 | |
1375 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) |
1376 | blk_rq_set_mixed_merge(req); |
1377 | |
1378 | bio->bi_next = req->bio; |
1379 | req->bio = bio; |
1380 | |
1381 | /* |
1382 | * may not be valid. if the low level driver said |
1383 | * it didn't need a bounce buffer then it better |
1384 | * not touch req->buffer either... |
1385 | */ |
1386 | req->buffer = bio_data(bio); |
1387 | req->__sector = bio->bi_sector; |
1388 | req->__data_len += bio->bi_size; |
1389 | req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); |
1390 | |
1391 | drive_stat_acct(req, 0); |
1392 | return true; |
1393 | } |
1394 | |
1395 | /** |
1396 | * attempt_plug_merge - try to merge with %current's plugged list |
1397 | * @q: request_queue new bio is being queued at |
1398 | * @bio: new bio being queued |
1399 | * @request_count: out parameter for number of traversed plugged requests |
1400 | * |
1401 | * Determine whether @bio being queued on @q can be merged with a request |
1402 | * on %current's plugged list. Returns %true if merge was successful, |
1403 | * otherwise %false. |
1404 | * |
1405 | * Plugging coalesces IOs from the same issuer for the same purpose without |
1406 | * going through @q->queue_lock. As such it's more of an issuing mechanism |
1407 | * than scheduling, and the request, while may have elvpriv data, is not |
1408 | * added on the elevator at this point. In addition, we don't have |
1409 | * reliable access to the elevator outside queue lock. Only check basic |
1410 | * merging parameters without querying the elevator. |
1411 | */ |
1412 | static bool attempt_plug_merge(struct request_queue *q, struct bio *bio, |
1413 | unsigned int *request_count) |
1414 | { |
1415 | struct blk_plug *plug; |
1416 | struct request *rq; |
1417 | bool ret = false; |
1418 | |
1419 | plug = current->plug; |
1420 | if (!plug) |
1421 | goto out; |
1422 | *request_count = 0; |
1423 | |
1424 | list_for_each_entry_reverse(rq, &plug->list, queuelist) { |
1425 | int el_ret; |
1426 | |
1427 | if (rq->q == q) |
1428 | (*request_count)++; |
1429 | |
1430 | if (rq->q != q || !blk_rq_merge_ok(rq, bio)) |
1431 | continue; |
1432 | |
1433 | el_ret = blk_try_merge(rq, bio); |
1434 | if (el_ret == ELEVATOR_BACK_MERGE) { |
1435 | ret = bio_attempt_back_merge(q, rq, bio); |
1436 | if (ret) |
1437 | break; |
1438 | } else if (el_ret == ELEVATOR_FRONT_MERGE) { |
1439 | ret = bio_attempt_front_merge(q, rq, bio); |
1440 | if (ret) |
1441 | break; |
1442 | } |
1443 | } |
1444 | out: |
1445 | return ret; |
1446 | } |
1447 | |
1448 | void init_request_from_bio(struct request *req, struct bio *bio) |
1449 | { |
1450 | req->cmd_type = REQ_TYPE_FS; |
1451 | |
1452 | req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK; |
1453 | if (bio->bi_rw & REQ_RAHEAD) |
1454 | req->cmd_flags |= REQ_FAILFAST_MASK; |
1455 | |
1456 | req->errors = 0; |
1457 | req->__sector = bio->bi_sector; |
1458 | req->ioprio = bio_prio(bio); |
1459 | blk_rq_bio_prep(req->q, req, bio); |
1460 | } |
1461 | |
1462 | void blk_queue_bio(struct request_queue *q, struct bio *bio) |
1463 | { |
1464 | const bool sync = !!(bio->bi_rw & REQ_SYNC); |
1465 | struct blk_plug *plug; |
1466 | int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT; |
1467 | struct request *req; |
1468 | unsigned int request_count = 0; |
1469 | |
1470 | /* |
1471 | * low level driver can indicate that it wants pages above a |
1472 | * certain limit bounced to low memory (ie for highmem, or even |
1473 | * ISA dma in theory) |
1474 | */ |
1475 | blk_queue_bounce(q, &bio); |
1476 | |
1477 | if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) { |
1478 | bio_endio(bio, -EIO); |
1479 | return; |
1480 | } |
1481 | |
1482 | if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) { |
1483 | spin_lock_irq(q->queue_lock); |
1484 | where = ELEVATOR_INSERT_FLUSH; |
1485 | goto get_rq; |
1486 | } |
1487 | |
1488 | /* |
1489 | * Check if we can merge with the plugged list before grabbing |
1490 | * any locks. |
1491 | */ |
1492 | if (attempt_plug_merge(q, bio, &request_count)) |
1493 | return; |
1494 | |
1495 | spin_lock_irq(q->queue_lock); |
1496 | |
1497 | el_ret = elv_merge(q, &req, bio); |
1498 | if (el_ret == ELEVATOR_BACK_MERGE) { |
1499 | if (bio_attempt_back_merge(q, req, bio)) { |
1500 | elv_bio_merged(q, req, bio); |
1501 | if (!attempt_back_merge(q, req)) |
1502 | elv_merged_request(q, req, el_ret); |
1503 | goto out_unlock; |
1504 | } |
1505 | } else if (el_ret == ELEVATOR_FRONT_MERGE) { |
1506 | if (bio_attempt_front_merge(q, req, bio)) { |
1507 | elv_bio_merged(q, req, bio); |
1508 | if (!attempt_front_merge(q, req)) |
1509 | elv_merged_request(q, req, el_ret); |
1510 | goto out_unlock; |
1511 | } |
1512 | } |
1513 | |
1514 | get_rq: |
1515 | /* |
1516 | * This sync check and mask will be re-done in init_request_from_bio(), |
1517 | * but we need to set it earlier to expose the sync flag to the |
1518 | * rq allocator and io schedulers. |
1519 | */ |
1520 | rw_flags = bio_data_dir(bio); |
1521 | if (sync) |
1522 | rw_flags |= REQ_SYNC; |
1523 | |
1524 | /* |
1525 | * Grab a free request. This is might sleep but can not fail. |
1526 | * Returns with the queue unlocked. |
1527 | */ |
1528 | req = get_request(q, rw_flags, bio, GFP_NOIO); |
1529 | if (unlikely(!req)) { |
1530 | bio_endio(bio, -ENODEV); /* @q is dead */ |
1531 | goto out_unlock; |
1532 | } |
1533 | |
1534 | /* |
1535 | * After dropping the lock and possibly sleeping here, our request |
1536 | * may now be mergeable after it had proven unmergeable (above). |
1537 | * We don't worry about that case for efficiency. It won't happen |
1538 | * often, and the elevators are able to handle it. |
1539 | */ |
1540 | init_request_from_bio(req, bio); |
1541 | |
1542 | if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) |
1543 | req->cpu = raw_smp_processor_id(); |
1544 | |
1545 | plug = current->plug; |
1546 | if (plug) { |
1547 | /* |
1548 | * If this is the first request added after a plug, fire |
1549 | * of a plug trace. If others have been added before, check |
1550 | * if we have multiple devices in this plug. If so, make a |
1551 | * note to sort the list before dispatch. |
1552 | */ |
1553 | if (list_empty(&plug->list)) |
1554 | trace_block_plug(q); |
1555 | else { |
1556 | if (request_count >= BLK_MAX_REQUEST_COUNT) { |
1557 | blk_flush_plug_list(plug, false); |
1558 | trace_block_plug(q); |
1559 | } |
1560 | } |
1561 | list_add_tail(&req->queuelist, &plug->list); |
1562 | drive_stat_acct(req, 1); |
1563 | } else { |
1564 | spin_lock_irq(q->queue_lock); |
1565 | add_acct_request(q, req, where); |
1566 | __blk_run_queue(q); |
1567 | out_unlock: |
1568 | spin_unlock_irq(q->queue_lock); |
1569 | } |
1570 | } |
1571 | EXPORT_SYMBOL_GPL(blk_queue_bio); /* for device mapper only */ |
1572 | |
1573 | /* |
1574 | * If bio->bi_dev is a partition, remap the location |
1575 | */ |
1576 | static inline void blk_partition_remap(struct bio *bio) |
1577 | { |
1578 | struct block_device *bdev = bio->bi_bdev; |
1579 | |
1580 | if (bio_sectors(bio) && bdev != bdev->bd_contains) { |
1581 | struct hd_struct *p = bdev->bd_part; |
1582 | |
1583 | bio->bi_sector += p->start_sect; |
1584 | bio->bi_bdev = bdev->bd_contains; |
1585 | |
1586 | trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio, |
1587 | bdev->bd_dev, |
1588 | bio->bi_sector - p->start_sect); |
1589 | } |
1590 | } |
1591 | |
1592 | static void handle_bad_sector(struct bio *bio) |
1593 | { |
1594 | char b[BDEVNAME_SIZE]; |
1595 | |
1596 | printk(KERN_INFO "attempt to access beyond end of device\n"); |
1597 | printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n", |
1598 | bdevname(bio->bi_bdev, b), |
1599 | bio->bi_rw, |
1600 | (unsigned long long)bio->bi_sector + bio_sectors(bio), |
1601 | (long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9)); |
1602 | |
1603 | set_bit(BIO_EOF, &bio->bi_flags); |
1604 | } |
1605 | |
1606 | #ifdef CONFIG_FAIL_MAKE_REQUEST |
1607 | |
1608 | static DECLARE_FAULT_ATTR(fail_make_request); |
1609 | |
1610 | static int __init setup_fail_make_request(char *str) |
1611 | { |
1612 | return setup_fault_attr(&fail_make_request, str); |
1613 | } |
1614 | __setup("fail_make_request=", setup_fail_make_request); |
1615 | |
1616 | static bool should_fail_request(struct hd_struct *part, unsigned int bytes) |
1617 | { |
1618 | return part->make_it_fail && should_fail(&fail_make_request, bytes); |
1619 | } |
1620 | |
1621 | static int __init fail_make_request_debugfs(void) |
1622 | { |
1623 | struct dentry *dir = fault_create_debugfs_attr("fail_make_request", |
1624 | NULL, &fail_make_request); |
1625 | |
1626 | return IS_ERR(dir) ? PTR_ERR(dir) : 0; |
1627 | } |
1628 | |
1629 | late_initcall(fail_make_request_debugfs); |
1630 | |
1631 | #else /* CONFIG_FAIL_MAKE_REQUEST */ |
1632 | |
1633 | static inline bool should_fail_request(struct hd_struct *part, |
1634 | unsigned int bytes) |
1635 | { |
1636 | return false; |
1637 | } |
1638 | |
1639 | #endif /* CONFIG_FAIL_MAKE_REQUEST */ |
1640 | |
1641 | /* |
1642 | * Check whether this bio extends beyond the end of the device. |
1643 | */ |
1644 | static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors) |
1645 | { |
1646 | sector_t maxsector; |
1647 | |
1648 | if (!nr_sectors) |
1649 | return 0; |
1650 | |
1651 | /* Test device or partition size, when known. */ |
1652 | maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9; |
1653 | if (maxsector) { |
1654 | sector_t sector = bio->bi_sector; |
1655 | |
1656 | if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { |
1657 | /* |
1658 | * This may well happen - the kernel calls bread() |
1659 | * without checking the size of the device, e.g., when |
1660 | * mounting a device. |
1661 | */ |
1662 | handle_bad_sector(bio); |
1663 | return 1; |
1664 | } |
1665 | } |
1666 | |
1667 | return 0; |
1668 | } |
1669 | |
1670 | static noinline_for_stack bool |
1671 | generic_make_request_checks(struct bio *bio) |
1672 | { |
1673 | struct request_queue *q; |
1674 | int nr_sectors = bio_sectors(bio); |
1675 | int err = -EIO; |
1676 | char b[BDEVNAME_SIZE]; |
1677 | struct hd_struct *part; |
1678 | |
1679 | might_sleep(); |
1680 | |
1681 | if (bio_check_eod(bio, nr_sectors)) |
1682 | goto end_io; |
1683 | |
1684 | q = bdev_get_queue(bio->bi_bdev); |
1685 | if (unlikely(!q)) { |
1686 | printk(KERN_ERR |
1687 | "generic_make_request: Trying to access " |
1688 | "nonexistent block-device %s (%Lu)\n", |
1689 | bdevname(bio->bi_bdev, b), |
1690 | (long long) bio->bi_sector); |
1691 | goto end_io; |
1692 | } |
1693 | |
1694 | if (likely(bio_is_rw(bio) && |
1695 | nr_sectors > queue_max_hw_sectors(q))) { |
1696 | printk(KERN_ERR "bio too big device %s (%u > %u)\n", |
1697 | bdevname(bio->bi_bdev, b), |
1698 | bio_sectors(bio), |
1699 | queue_max_hw_sectors(q)); |
1700 | goto end_io; |
1701 | } |
1702 | |
1703 | part = bio->bi_bdev->bd_part; |
1704 | if (should_fail_request(part, bio->bi_size) || |
1705 | should_fail_request(&part_to_disk(part)->part0, |
1706 | bio->bi_size)) |
1707 | goto end_io; |
1708 | |
1709 | /* |
1710 | * If this device has partitions, remap block n |
1711 | * of partition p to block n+start(p) of the disk. |
1712 | */ |
1713 | blk_partition_remap(bio); |
1714 | |
1715 | if (bio_check_eod(bio, nr_sectors)) |
1716 | goto end_io; |
1717 | |
1718 | /* |
1719 | * Filter flush bio's early so that make_request based |
1720 | * drivers without flush support don't have to worry |
1721 | * about them. |
1722 | */ |
1723 | if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) { |
1724 | bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA); |
1725 | if (!nr_sectors) { |
1726 | err = 0; |
1727 | goto end_io; |
1728 | } |
1729 | } |
1730 | |
1731 | if ((bio->bi_rw & REQ_DISCARD) && |
1732 | (!blk_queue_discard(q) || |
1733 | ((bio->bi_rw & REQ_SECURE) && !blk_queue_secdiscard(q)))) { |
1734 | err = -EOPNOTSUPP; |
1735 | goto end_io; |
1736 | } |
1737 | |
1738 | if (bio->bi_rw & REQ_WRITE_SAME && !bdev_write_same(bio->bi_bdev)) { |
1739 | err = -EOPNOTSUPP; |
1740 | goto end_io; |
1741 | } |
1742 | |
1743 | /* |
1744 | * Various block parts want %current->io_context and lazy ioc |
1745 | * allocation ends up trading a lot of pain for a small amount of |
1746 | * memory. Just allocate it upfront. This may fail and block |
1747 | * layer knows how to live with it. |
1748 | */ |
1749 | create_io_context(GFP_ATOMIC, q->node); |
1750 | |
1751 | if (blk_throtl_bio(q, bio)) |
1752 | return false; /* throttled, will be resubmitted later */ |
1753 | |
1754 | trace_block_bio_queue(q, bio); |
1755 | return true; |
1756 | |
1757 | end_io: |
1758 | bio_endio(bio, err); |
1759 | return false; |
1760 | } |
1761 | |
1762 | /** |
1763 | * generic_make_request - hand a buffer to its device driver for I/O |
1764 | * @bio: The bio describing the location in memory and on the device. |
1765 | * |
1766 | * generic_make_request() is used to make I/O requests of block |
1767 | * devices. It is passed a &struct bio, which describes the I/O that needs |
1768 | * to be done. |
1769 | * |
1770 | * generic_make_request() does not return any status. The |
1771 | * success/failure status of the request, along with notification of |
1772 | * completion, is delivered asynchronously through the bio->bi_end_io |
1773 | * function described (one day) else where. |
1774 | * |
1775 | * The caller of generic_make_request must make sure that bi_io_vec |
1776 | * are set to describe the memory buffer, and that bi_dev and bi_sector are |
1777 | * set to describe the device address, and the |
1778 | * bi_end_io and optionally bi_private are set to describe how |
1779 | * completion notification should be signaled. |
1780 | * |
1781 | * generic_make_request and the drivers it calls may use bi_next if this |
1782 | * bio happens to be merged with someone else, and may resubmit the bio to |
1783 | * a lower device by calling into generic_make_request recursively, which |
1784 | * means the bio should NOT be touched after the call to ->make_request_fn. |
1785 | */ |
1786 | void generic_make_request(struct bio *bio) |
1787 | { |
1788 | struct bio_list bio_list_on_stack; |
1789 | |
1790 | if (!generic_make_request_checks(bio)) |
1791 | return; |
1792 | |
1793 | /* |
1794 | * We only want one ->make_request_fn to be active at a time, else |
1795 | * stack usage with stacked devices could be a problem. So use |
1796 | * current->bio_list to keep a list of requests submited by a |
1797 | * make_request_fn function. current->bio_list is also used as a |
1798 | * flag to say if generic_make_request is currently active in this |
1799 | * task or not. If it is NULL, then no make_request is active. If |
1800 | * it is non-NULL, then a make_request is active, and new requests |
1801 | * should be added at the tail |
1802 | */ |
1803 | if (current->bio_list) { |
1804 | bio_list_add(current->bio_list, bio); |
1805 | return; |
1806 | } |
1807 | |
1808 | /* following loop may be a bit non-obvious, and so deserves some |
1809 | * explanation. |
1810 | * Before entering the loop, bio->bi_next is NULL (as all callers |
1811 | * ensure that) so we have a list with a single bio. |
1812 | * We pretend that we have just taken it off a longer list, so |
1813 | * we assign bio_list to a pointer to the bio_list_on_stack, |
1814 | * thus initialising the bio_list of new bios to be |
1815 | * added. ->make_request() may indeed add some more bios |
1816 | * through a recursive call to generic_make_request. If it |
1817 | * did, we find a non-NULL value in bio_list and re-enter the loop |
1818 | * from the top. In this case we really did just take the bio |
1819 | * of the top of the list (no pretending) and so remove it from |
1820 | * bio_list, and call into ->make_request() again. |
1821 | */ |
1822 | BUG_ON(bio->bi_next); |
1823 | bio_list_init(&bio_list_on_stack); |
1824 | current->bio_list = &bio_list_on_stack; |
1825 | do { |
1826 | struct request_queue *q = bdev_get_queue(bio->bi_bdev); |
1827 | |
1828 | q->make_request_fn(q, bio); |
1829 | |
1830 | bio = bio_list_pop(current->bio_list); |
1831 | } while (bio); |
1832 | current->bio_list = NULL; /* deactivate */ |
1833 | } |
1834 | EXPORT_SYMBOL(generic_make_request); |
1835 | |
1836 | /** |
1837 | * submit_bio - submit a bio to the block device layer for I/O |
1838 | * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) |
1839 | * @bio: The &struct bio which describes the I/O |
1840 | * |
1841 | * submit_bio() is very similar in purpose to generic_make_request(), and |
1842 | * uses that function to do most of the work. Both are fairly rough |
1843 | * interfaces; @bio must be presetup and ready for I/O. |
1844 | * |
1845 | */ |
1846 | void submit_bio(int rw, struct bio *bio) |
1847 | { |
1848 | bio->bi_rw |= rw; |
1849 | |
1850 | /* |
1851 | * If it's a regular read/write or a barrier with data attached, |
1852 | * go through the normal accounting stuff before submission. |
1853 | */ |
1854 | if (bio_has_data(bio)) { |
1855 | unsigned int count; |
1856 | |
1857 | if (unlikely(rw & REQ_WRITE_SAME)) |
1858 | count = bdev_logical_block_size(bio->bi_bdev) >> 9; |
1859 | else |
1860 | count = bio_sectors(bio); |
1861 | |
1862 | if (rw & WRITE) { |
1863 | count_vm_events(PGPGOUT, count); |
1864 | } else { |
1865 | task_io_account_read(bio->bi_size); |
1866 | count_vm_events(PGPGIN, count); |
1867 | } |
1868 | |
1869 | if (unlikely(block_dump)) { |
1870 | char b[BDEVNAME_SIZE]; |
1871 | printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n", |
1872 | current->comm, task_pid_nr(current), |
1873 | (rw & WRITE) ? "WRITE" : "READ", |
1874 | (unsigned long long)bio->bi_sector, |
1875 | bdevname(bio->bi_bdev, b), |
1876 | count); |
1877 | } |
1878 | } |
1879 | |
1880 | generic_make_request(bio); |
1881 | } |
1882 | EXPORT_SYMBOL(submit_bio); |
1883 | |
1884 | /** |
1885 | * blk_rq_check_limits - Helper function to check a request for the queue limit |
1886 | * @q: the queue |
1887 | * @rq: the request being checked |
1888 | * |
1889 | * Description: |
1890 | * @rq may have been made based on weaker limitations of upper-level queues |
1891 | * in request stacking drivers, and it may violate the limitation of @q. |
1892 | * Since the block layer and the underlying device driver trust @rq |
1893 | * after it is inserted to @q, it should be checked against @q before |
1894 | * the insertion using this generic function. |
1895 | * |
1896 | * This function should also be useful for request stacking drivers |
1897 | * in some cases below, so export this function. |
1898 | * Request stacking drivers like request-based dm may change the queue |
1899 | * limits while requests are in the queue (e.g. dm's table swapping). |
1900 | * Such request stacking drivers should check those requests agaist |
1901 | * the new queue limits again when they dispatch those requests, |
1902 | * although such checkings are also done against the old queue limits |
1903 | * when submitting requests. |
1904 | */ |
1905 | int blk_rq_check_limits(struct request_queue *q, struct request *rq) |
1906 | { |
1907 | if (!rq_mergeable(rq)) |
1908 | return 0; |
1909 | |
1910 | if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, rq->cmd_flags)) { |
1911 | printk(KERN_ERR "%s: over max size limit.\n", __func__); |
1912 | return -EIO; |
1913 | } |
1914 | |
1915 | /* |
1916 | * queue's settings related to segment counting like q->bounce_pfn |
1917 | * may differ from that of other stacking queues. |
1918 | * Recalculate it to check the request correctly on this queue's |
1919 | * limitation. |
1920 | */ |
1921 | blk_recalc_rq_segments(rq); |
1922 | if (rq->nr_phys_segments > queue_max_segments(q)) { |
1923 | printk(KERN_ERR "%s: over max segments limit.\n", __func__); |
1924 | return -EIO; |
1925 | } |
1926 | |
1927 | return 0; |
1928 | } |
1929 | EXPORT_SYMBOL_GPL(blk_rq_check_limits); |
1930 | |
1931 | /** |
1932 | * blk_insert_cloned_request - Helper for stacking drivers to submit a request |
1933 | * @q: the queue to submit the request |
1934 | * @rq: the request being queued |
1935 | */ |
1936 | int blk_insert_cloned_request(struct request_queue *q, struct request *rq) |
1937 | { |
1938 | unsigned long flags; |
1939 | int where = ELEVATOR_INSERT_BACK; |
1940 | |
1941 | if (blk_rq_check_limits(q, rq)) |
1942 | return -EIO; |
1943 | |
1944 | if (rq->rq_disk && |
1945 | should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq))) |
1946 | return -EIO; |
1947 | |
1948 | spin_lock_irqsave(q->queue_lock, flags); |
1949 | if (unlikely(blk_queue_dying(q))) { |
1950 | spin_unlock_irqrestore(q->queue_lock, flags); |
1951 | return -ENODEV; |
1952 | } |
1953 | |
1954 | /* |
1955 | * Submitting request must be dequeued before calling this function |
1956 | * because it will be linked to another request_queue |
1957 | */ |
1958 | BUG_ON(blk_queued_rq(rq)); |
1959 | |
1960 | if (rq->cmd_flags & (REQ_FLUSH|REQ_FUA)) |
1961 | where = ELEVATOR_INSERT_FLUSH; |
1962 | |
1963 | add_acct_request(q, rq, where); |
1964 | if (where == ELEVATOR_INSERT_FLUSH) |
1965 | __blk_run_queue(q); |
1966 | spin_unlock_irqrestore(q->queue_lock, flags); |
1967 | |
1968 | return 0; |
1969 | } |
1970 | EXPORT_SYMBOL_GPL(blk_insert_cloned_request); |
1971 | |
1972 | /** |
1973 | * blk_rq_err_bytes - determine number of bytes till the next failure boundary |
1974 | * @rq: request to examine |
1975 | * |
1976 | * Description: |
1977 | * A request could be merge of IOs which require different failure |
1978 | * handling. This function determines the number of bytes which |
1979 | * can be failed from the beginning of the request without |
1980 | * crossing into area which need to be retried further. |
1981 | * |
1982 | * Return: |
1983 | * The number of bytes to fail. |
1984 | * |
1985 | * Context: |
1986 | * queue_lock must be held. |
1987 | */ |
1988 | unsigned int blk_rq_err_bytes(const struct request *rq) |
1989 | { |
1990 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; |
1991 | unsigned int bytes = 0; |
1992 | struct bio *bio; |
1993 | |
1994 | if (!(rq->cmd_flags & REQ_MIXED_MERGE)) |
1995 | return blk_rq_bytes(rq); |
1996 | |
1997 | /* |
1998 | * Currently the only 'mixing' which can happen is between |
1999 | * different fastfail types. We can safely fail portions |
2000 | * which have all the failfast bits that the first one has - |
2001 | * the ones which are at least as eager to fail as the first |
2002 | * one. |
2003 | */ |
2004 | for (bio = rq->bio; bio; bio = bio->bi_next) { |
2005 | if ((bio->bi_rw & ff) != ff) |
2006 | break; |
2007 | bytes += bio->bi_size; |
2008 | } |
2009 | |
2010 | /* this could lead to infinite loop */ |
2011 | BUG_ON(blk_rq_bytes(rq) && !bytes); |
2012 | return bytes; |
2013 | } |
2014 | EXPORT_SYMBOL_GPL(blk_rq_err_bytes); |
2015 | |
2016 | static void blk_account_io_completion(struct request *req, unsigned int bytes) |
2017 | { |
2018 | if (blk_do_io_stat(req)) { |
2019 | const int rw = rq_data_dir(req); |
2020 | struct hd_struct *part; |
2021 | int cpu; |
2022 | |
2023 | cpu = part_stat_lock(); |
2024 | part = req->part; |
2025 | part_stat_add(cpu, part, sectors[rw], bytes >> 9); |
2026 | part_stat_unlock(); |
2027 | } |
2028 | } |
2029 | |
2030 | static void blk_account_io_done(struct request *req) |
2031 | { |
2032 | /* |
2033 | * Account IO completion. flush_rq isn't accounted as a |
2034 | * normal IO on queueing nor completion. Accounting the |
2035 | * containing request is enough. |
2036 | */ |
2037 | if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) { |
2038 | unsigned long duration = jiffies - req->start_time; |
2039 | const int rw = rq_data_dir(req); |
2040 | struct hd_struct *part; |
2041 | int cpu; |
2042 | |
2043 | cpu = part_stat_lock(); |
2044 | part = req->part; |
2045 | |
2046 | part_stat_inc(cpu, part, ios[rw]); |
2047 | part_stat_add(cpu, part, ticks[rw], duration); |
2048 | part_round_stats(cpu, part); |
2049 | part_dec_in_flight(part, rw); |
2050 | |
2051 | hd_struct_put(part); |
2052 | part_stat_unlock(); |
2053 | } |
2054 | } |
2055 | |
2056 | /** |
2057 | * blk_peek_request - peek at the top of a request queue |
2058 | * @q: request queue to peek at |
2059 | * |
2060 | * Description: |
2061 | * Return the request at the top of @q. The returned request |
2062 | * should be started using blk_start_request() before LLD starts |
2063 | * processing it. |
2064 | * |
2065 | * Return: |
2066 | * Pointer to the request at the top of @q if available. Null |
2067 | * otherwise. |
2068 | * |
2069 | * Context: |
2070 | * queue_lock must be held. |
2071 | */ |
2072 | struct request *blk_peek_request(struct request_queue *q) |
2073 | { |
2074 | struct request *rq; |
2075 | int ret; |
2076 | |
2077 | while ((rq = __elv_next_request(q)) != NULL) { |
2078 | if (!(rq->cmd_flags & REQ_STARTED)) { |
2079 | /* |
2080 | * This is the first time the device driver |
2081 | * sees this request (possibly after |
2082 | * requeueing). Notify IO scheduler. |
2083 | */ |
2084 | if (rq->cmd_flags & REQ_SORTED) |
2085 | elv_activate_rq(q, rq); |
2086 | |
2087 | /* |
2088 | * just mark as started even if we don't start |
2089 | * it, a request that has been delayed should |
2090 | * not be passed by new incoming requests |
2091 | */ |
2092 | rq->cmd_flags |= REQ_STARTED; |
2093 | trace_block_rq_issue(q, rq); |
2094 | } |
2095 | |
2096 | if (!q->boundary_rq || q->boundary_rq == rq) { |
2097 | q->end_sector = rq_end_sector(rq); |
2098 | q->boundary_rq = NULL; |
2099 | } |
2100 | |
2101 | if (rq->cmd_flags & REQ_DONTPREP) |
2102 | break; |
2103 | |
2104 | if (q->dma_drain_size && blk_rq_bytes(rq)) { |
2105 | /* |
2106 | * make sure space for the drain appears we |
2107 | * know we can do this because max_hw_segments |
2108 | * has been adjusted to be one fewer than the |
2109 | * device can handle |
2110 | */ |
2111 | rq->nr_phys_segments++; |
2112 | } |
2113 | |
2114 | if (!q->prep_rq_fn) |
2115 | break; |
2116 | |
2117 | ret = q->prep_rq_fn(q, rq); |
2118 | if (ret == BLKPREP_OK) { |
2119 | break; |
2120 | } else if (ret == BLKPREP_DEFER) { |
2121 | /* |
2122 | * the request may have been (partially) prepped. |
2123 | * we need to keep this request in the front to |
2124 | * avoid resource deadlock. REQ_STARTED will |
2125 | * prevent other fs requests from passing this one. |
2126 | */ |
2127 | if (q->dma_drain_size && blk_rq_bytes(rq) && |
2128 | !(rq->cmd_flags & REQ_DONTPREP)) { |
2129 | /* |
2130 | * remove the space for the drain we added |
2131 | * so that we don't add it again |
2132 | */ |
2133 | --rq->nr_phys_segments; |
2134 | } |
2135 | |
2136 | rq = NULL; |
2137 | break; |
2138 | } else if (ret == BLKPREP_KILL) { |
2139 | rq->cmd_flags |= REQ_QUIET; |
2140 | /* |
2141 | * Mark this request as started so we don't trigger |
2142 | * any debug logic in the end I/O path. |
2143 | */ |
2144 | blk_start_request(rq); |
2145 | __blk_end_request_all(rq, -EIO); |
2146 | } else { |
2147 | printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); |
2148 | break; |
2149 | } |
2150 | } |
2151 | |
2152 | return rq; |
2153 | } |
2154 | EXPORT_SYMBOL(blk_peek_request); |
2155 | |
2156 | void blk_dequeue_request(struct request *rq) |
2157 | { |
2158 | struct request_queue *q = rq->q; |
2159 | |
2160 | BUG_ON(list_empty(&rq->queuelist)); |
2161 | BUG_ON(ELV_ON_HASH(rq)); |
2162 | |
2163 | list_del_init(&rq->queuelist); |
2164 | |
2165 | /* |
2166 | * the time frame between a request being removed from the lists |
2167 | * and to it is freed is accounted as io that is in progress at |
2168 | * the driver side. |
2169 | */ |
2170 | if (blk_account_rq(rq)) { |
2171 | q->in_flight[rq_is_sync(rq)]++; |
2172 | set_io_start_time_ns(rq); |
2173 | } |
2174 | } |
2175 | |
2176 | /** |
2177 | * blk_start_request - start request processing on the driver |
2178 | * @req: request to dequeue |
2179 | * |
2180 | * Description: |
2181 | * Dequeue @req and start timeout timer on it. This hands off the |
2182 | * request to the driver. |
2183 | * |
2184 | * Block internal functions which don't want to start timer should |
2185 | * call blk_dequeue_request(). |
2186 | * |
2187 | * Context: |
2188 | * queue_lock must be held. |
2189 | */ |
2190 | void blk_start_request(struct request *req) |
2191 | { |
2192 | blk_dequeue_request(req); |
2193 | |
2194 | /* |
2195 | * We are now handing the request to the hardware, initialize |
2196 | * resid_len to full count and add the timeout handler. |
2197 | */ |
2198 | req->resid_len = blk_rq_bytes(req); |
2199 | if (unlikely(blk_bidi_rq(req))) |
2200 | req->next_rq->resid_len = blk_rq_bytes(req->next_rq); |
2201 | |
2202 | blk_add_timer(req); |
2203 | } |
2204 | EXPORT_SYMBOL(blk_start_request); |
2205 | |
2206 | /** |
2207 | * blk_fetch_request - fetch a request from a request queue |
2208 | * @q: request queue to fetch a request from |
2209 | * |
2210 | * Description: |
2211 | * Return the request at the top of @q. The request is started on |
2212 | * return and LLD can start processing it immediately. |
2213 | * |
2214 | * Return: |
2215 | * Pointer to the request at the top of @q if available. Null |
2216 | * otherwise. |
2217 | * |
2218 | * Context: |
2219 | * queue_lock must be held. |
2220 | */ |
2221 | struct request *blk_fetch_request(struct request_queue *q) |
2222 | { |
2223 | struct request *rq; |
2224 | |
2225 | rq = blk_peek_request(q); |
2226 | if (rq) |
2227 | blk_start_request(rq); |
2228 | return rq; |
2229 | } |
2230 | EXPORT_SYMBOL(blk_fetch_request); |
2231 | |
2232 | /** |
2233 | * blk_update_request - Special helper function for request stacking drivers |
2234 | * @req: the request being processed |
2235 | * @error: %0 for success, < %0 for error |
2236 | * @nr_bytes: number of bytes to complete @req |
2237 | * |
2238 | * Description: |
2239 | * Ends I/O on a number of bytes attached to @req, but doesn't complete |
2240 | * the request structure even if @req doesn't have leftover. |
2241 | * If @req has leftover, sets it up for the next range of segments. |
2242 | * |
2243 | * This special helper function is only for request stacking drivers |
2244 | * (e.g. request-based dm) so that they can handle partial completion. |
2245 | * Actual device drivers should use blk_end_request instead. |
2246 | * |
2247 | * Passing the result of blk_rq_bytes() as @nr_bytes guarantees |
2248 | * %false return from this function. |
2249 | * |
2250 | * Return: |
2251 | * %false - this request doesn't have any more data |
2252 | * %true - this request has more data |
2253 | **/ |
2254 | bool blk_update_request(struct request *req, int error, unsigned int nr_bytes) |
2255 | { |
2256 | int total_bytes, bio_nbytes, next_idx = 0; |
2257 | struct bio *bio; |
2258 | |
2259 | if (!req->bio) |
2260 | return false; |
2261 | |
2262 | trace_block_rq_complete(req->q, req); |
2263 | |
2264 | /* |
2265 | * For fs requests, rq is just carrier of independent bio's |
2266 | * and each partial completion should be handled separately. |
2267 | * Reset per-request error on each partial completion. |
2268 | * |
2269 | * TODO: tj: This is too subtle. It would be better to let |
2270 | * low level drivers do what they see fit. |
2271 | */ |
2272 | if (req->cmd_type == REQ_TYPE_FS) |
2273 | req->errors = 0; |
2274 | |
2275 | if (error && req->cmd_type == REQ_TYPE_FS && |
2276 | !(req->cmd_flags & REQ_QUIET)) { |
2277 | char *error_type; |
2278 | |
2279 | switch (error) { |
2280 | case -ENOLINK: |
2281 | error_type = "recoverable transport"; |
2282 | break; |
2283 | case -EREMOTEIO: |
2284 | error_type = "critical target"; |
2285 | break; |
2286 | case -EBADE: |
2287 | error_type = "critical nexus"; |
2288 | break; |
2289 | case -EIO: |
2290 | default: |
2291 | error_type = "I/O"; |
2292 | break; |
2293 | } |
2294 | printk_ratelimited(KERN_ERR "end_request: %s error, dev %s, sector %llu\n", |
2295 | error_type, req->rq_disk ? |
2296 | req->rq_disk->disk_name : "?", |
2297 | (unsigned long long)blk_rq_pos(req)); |
2298 | |
2299 | } |
2300 | |
2301 | blk_account_io_completion(req, nr_bytes); |
2302 | |
2303 | total_bytes = bio_nbytes = 0; |
2304 | while ((bio = req->bio) != NULL) { |
2305 | int nbytes; |
2306 | |
2307 | if (nr_bytes >= bio->bi_size) { |
2308 | req->bio = bio->bi_next; |
2309 | nbytes = bio->bi_size; |
2310 | req_bio_endio(req, bio, nbytes, error); |
2311 | next_idx = 0; |
2312 | bio_nbytes = 0; |
2313 | } else { |
2314 | int idx = bio->bi_idx + next_idx; |
2315 | |
2316 | if (unlikely(idx >= bio->bi_vcnt)) { |
2317 | blk_dump_rq_flags(req, "__end_that"); |
2318 | printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n", |
2319 | __func__, idx, bio->bi_vcnt); |
2320 | break; |
2321 | } |
2322 | |
2323 | nbytes = bio_iovec_idx(bio, idx)->bv_len; |
2324 | BIO_BUG_ON(nbytes > bio->bi_size); |
2325 | |
2326 | /* |
2327 | * not a complete bvec done |
2328 | */ |
2329 | if (unlikely(nbytes > nr_bytes)) { |
2330 | bio_nbytes += nr_bytes; |
2331 | total_bytes += nr_bytes; |
2332 | break; |
2333 | } |
2334 | |
2335 | /* |
2336 | * advance to the next vector |
2337 | */ |
2338 | next_idx++; |
2339 | bio_nbytes += nbytes; |
2340 | } |
2341 | |
2342 | total_bytes += nbytes; |
2343 | nr_bytes -= nbytes; |
2344 | |
2345 | bio = req->bio; |
2346 | if (bio) { |
2347 | /* |
2348 | * end more in this run, or just return 'not-done' |
2349 | */ |
2350 | if (unlikely(nr_bytes <= 0)) |
2351 | break; |
2352 | } |
2353 | } |
2354 | |
2355 | /* |
2356 | * completely done |
2357 | */ |
2358 | if (!req->bio) { |
2359 | /* |
2360 | * Reset counters so that the request stacking driver |
2361 | * can find how many bytes remain in the request |
2362 | * later. |
2363 | */ |
2364 | req->__data_len = 0; |
2365 | return false; |
2366 | } |
2367 | |
2368 | /* |
2369 | * if the request wasn't completed, update state |
2370 | */ |
2371 | if (bio_nbytes) { |
2372 | req_bio_endio(req, bio, bio_nbytes, error); |
2373 | bio->bi_idx += next_idx; |
2374 | bio_iovec(bio)->bv_offset += nr_bytes; |
2375 | bio_iovec(bio)->bv_len -= nr_bytes; |
2376 | } |
2377 | |
2378 | req->__data_len -= total_bytes; |
2379 | req->buffer = bio_data(req->bio); |
2380 | |
2381 | /* update sector only for requests with clear definition of sector */ |
2382 | if (req->cmd_type == REQ_TYPE_FS) |
2383 | req->__sector += total_bytes >> 9; |
2384 | |
2385 | /* mixed attributes always follow the first bio */ |
2386 | if (req->cmd_flags & REQ_MIXED_MERGE) { |
2387 | req->cmd_flags &= ~REQ_FAILFAST_MASK; |
2388 | req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK; |
2389 | } |
2390 | |
2391 | /* |
2392 | * If total number of sectors is less than the first segment |
2393 | * size, something has gone terribly wrong. |
2394 | */ |
2395 | if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { |
2396 | blk_dump_rq_flags(req, "request botched"); |
2397 | req->__data_len = blk_rq_cur_bytes(req); |
2398 | } |
2399 | |
2400 | /* recalculate the number of segments */ |
2401 | blk_recalc_rq_segments(req); |
2402 | |
2403 | return true; |
2404 | } |
2405 | EXPORT_SYMBOL_GPL(blk_update_request); |
2406 | |
2407 | static bool blk_update_bidi_request(struct request *rq, int error, |
2408 | unsigned int nr_bytes, |
2409 | unsigned int bidi_bytes) |
2410 | { |
2411 | if (blk_update_request(rq, error, nr_bytes)) |
2412 | return true; |
2413 | |
2414 | /* Bidi request must be completed as a whole */ |
2415 | if (unlikely(blk_bidi_rq(rq)) && |
2416 | blk_update_request(rq->next_rq, error, bidi_bytes)) |
2417 | return true; |
2418 | |
2419 | if (blk_queue_add_random(rq->q)) |
2420 | add_disk_randomness(rq->rq_disk); |
2421 | |
2422 | return false; |
2423 | } |
2424 | |
2425 | /** |
2426 | * blk_unprep_request - unprepare a request |
2427 | * @req: the request |
2428 | * |
2429 | * This function makes a request ready for complete resubmission (or |
2430 | * completion). It happens only after all error handling is complete, |
2431 | * so represents the appropriate moment to deallocate any resources |
2432 | * that were allocated to the request in the prep_rq_fn. The queue |
2433 | * lock is held when calling this. |
2434 | */ |
2435 | void blk_unprep_request(struct request *req) |
2436 | { |
2437 | struct request_queue *q = req->q; |
2438 | |
2439 | req->cmd_flags &= ~REQ_DONTPREP; |
2440 | if (q->unprep_rq_fn) |
2441 | q->unprep_rq_fn(q, req); |
2442 | } |
2443 | EXPORT_SYMBOL_GPL(blk_unprep_request); |
2444 | |
2445 | /* |
2446 | * queue lock must be held |
2447 | */ |
2448 | static void blk_finish_request(struct request *req, int error) |
2449 | { |
2450 | if (blk_rq_tagged(req)) |
2451 | blk_queue_end_tag(req->q, req); |
2452 | |
2453 | BUG_ON(blk_queued_rq(req)); |
2454 | |
2455 | if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS) |
2456 | laptop_io_completion(&req->q->backing_dev_info); |
2457 | |
2458 | blk_delete_timer(req); |
2459 | |
2460 | if (req->cmd_flags & REQ_DONTPREP) |
2461 | blk_unprep_request(req); |
2462 | |
2463 | |
2464 | blk_account_io_done(req); |
2465 | |
2466 | if (req->end_io) |
2467 | req->end_io(req, error); |
2468 | else { |
2469 | if (blk_bidi_rq(req)) |
2470 | __blk_put_request(req->next_rq->q, req->next_rq); |
2471 | |
2472 | __blk_put_request(req->q, req); |
2473 | } |
2474 | } |
2475 | |
2476 | /** |
2477 | * blk_end_bidi_request - Complete a bidi request |
2478 | * @rq: the request to complete |
2479 | * @error: %0 for success, < %0 for error |
2480 | * @nr_bytes: number of bytes to complete @rq |
2481 | * @bidi_bytes: number of bytes to complete @rq->next_rq |
2482 | * |
2483 | * Description: |
2484 | * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. |
2485 | * Drivers that supports bidi can safely call this member for any |
2486 | * type of request, bidi or uni. In the later case @bidi_bytes is |
2487 | * just ignored. |
2488 | * |
2489 | * Return: |
2490 | * %false - we are done with this request |
2491 | * %true - still buffers pending for this request |
2492 | **/ |
2493 | static bool blk_end_bidi_request(struct request *rq, int error, |
2494 | unsigned int nr_bytes, unsigned int bidi_bytes) |
2495 | { |
2496 | struct request_queue *q = rq->q; |
2497 | unsigned long flags; |
2498 | |
2499 | if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) |
2500 | return true; |
2501 | |
2502 | spin_lock_irqsave(q->queue_lock, flags); |
2503 | blk_finish_request(rq, error); |
2504 | spin_unlock_irqrestore(q->queue_lock, flags); |
2505 | |
2506 | return false; |
2507 | } |
2508 | |
2509 | /** |
2510 | * __blk_end_bidi_request - Complete a bidi request with queue lock held |
2511 | * @rq: the request to complete |
2512 | * @error: %0 for success, < %0 for error |
2513 | * @nr_bytes: number of bytes to complete @rq |
2514 | * @bidi_bytes: number of bytes to complete @rq->next_rq |
2515 | * |
2516 | * Description: |
2517 | * Identical to blk_end_bidi_request() except that queue lock is |
2518 | * assumed to be locked on entry and remains so on return. |
2519 | * |
2520 | * Return: |
2521 | * %false - we are done with this request |
2522 | * %true - still buffers pending for this request |
2523 | **/ |
2524 | bool __blk_end_bidi_request(struct request *rq, int error, |
2525 | unsigned int nr_bytes, unsigned int bidi_bytes) |
2526 | { |
2527 | if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) |
2528 | return true; |
2529 | |
2530 | blk_finish_request(rq, error); |
2531 | |
2532 | return false; |
2533 | } |
2534 | |
2535 | /** |
2536 | * blk_end_request - Helper function for drivers to complete the request. |
2537 | * @rq: the request being processed |
2538 | * @error: %0 for success, < %0 for error |
2539 | * @nr_bytes: number of bytes to complete |
2540 | * |
2541 | * Description: |
2542 | * Ends I/O on a number of bytes attached to @rq. |
2543 | * If @rq has leftover, sets it up for the next range of segments. |
2544 | * |
2545 | * Return: |
2546 | * %false - we are done with this request |
2547 | * %true - still buffers pending for this request |
2548 | **/ |
2549 | bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes) |
2550 | { |
2551 | return blk_end_bidi_request(rq, error, nr_bytes, 0); |
2552 | } |
2553 | EXPORT_SYMBOL(blk_end_request); |
2554 | |
2555 | /** |
2556 | * blk_end_request_all - Helper function for drives to finish the request. |
2557 | * @rq: the request to finish |
2558 | * @error: %0 for success, < %0 for error |
2559 | * |
2560 | * Description: |
2561 | * Completely finish @rq. |
2562 | */ |
2563 | void blk_end_request_all(struct request *rq, int error) |
2564 | { |
2565 | bool pending; |
2566 | unsigned int bidi_bytes = 0; |
2567 | |
2568 | if (unlikely(blk_bidi_rq(rq))) |
2569 | bidi_bytes = blk_rq_bytes(rq->next_rq); |
2570 | |
2571 | pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); |
2572 | BUG_ON(pending); |
2573 | } |
2574 | EXPORT_SYMBOL(blk_end_request_all); |
2575 | |
2576 | /** |
2577 | * blk_end_request_cur - Helper function to finish the current request chunk. |
2578 | * @rq: the request to finish the current chunk for |
2579 | * @error: %0 for success, < %0 for error |
2580 | * |
2581 | * Description: |
2582 | * Complete the current consecutively mapped chunk from @rq. |
2583 | * |
2584 | * Return: |
2585 | * %false - we are done with this request |
2586 | * %true - still buffers pending for this request |
2587 | */ |
2588 | bool blk_end_request_cur(struct request *rq, int error) |
2589 | { |
2590 | return blk_end_request(rq, error, blk_rq_cur_bytes(rq)); |
2591 | } |
2592 | EXPORT_SYMBOL(blk_end_request_cur); |
2593 | |
2594 | /** |
2595 | * blk_end_request_err - Finish a request till the next failure boundary. |
2596 | * @rq: the request to finish till the next failure boundary for |
2597 | * @error: must be negative errno |
2598 | * |
2599 | * Description: |
2600 | * Complete @rq till the next failure boundary. |
2601 | * |
2602 | * Return: |
2603 | * %false - we are done with this request |
2604 | * %true - still buffers pending for this request |
2605 | */ |
2606 | bool blk_end_request_err(struct request *rq, int error) |
2607 | { |
2608 | WARN_ON(error >= 0); |
2609 | return blk_end_request(rq, error, blk_rq_err_bytes(rq)); |
2610 | } |
2611 | EXPORT_SYMBOL_GPL(blk_end_request_err); |
2612 | |
2613 | /** |
2614 | * __blk_end_request - Helper function for drivers to complete the request. |
2615 | * @rq: the request being processed |
2616 | * @error: %0 for success, < %0 for error |
2617 | * @nr_bytes: number of bytes to complete |
2618 | * |
2619 | * Description: |
2620 | * Must be called with queue lock held unlike blk_end_request(). |
2621 | * |
2622 | * Return: |
2623 | * %false - we are done with this request |
2624 | * %true - still buffers pending for this request |
2625 | **/ |
2626 | bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes) |
2627 | { |
2628 | return __blk_end_bidi_request(rq, error, nr_bytes, 0); |
2629 | } |
2630 | EXPORT_SYMBOL(__blk_end_request); |
2631 | |
2632 | /** |
2633 | * __blk_end_request_all - Helper function for drives to finish the request. |
2634 | * @rq: the request to finish |
2635 | * @error: %0 for success, < %0 for error |
2636 | * |
2637 | * Description: |
2638 | * Completely finish @rq. Must be called with queue lock held. |
2639 | */ |
2640 | void __blk_end_request_all(struct request *rq, int error) |
2641 | { |
2642 | bool pending; |
2643 | unsigned int bidi_bytes = 0; |
2644 | |
2645 | if (unlikely(blk_bidi_rq(rq))) |
2646 | bidi_bytes = blk_rq_bytes(rq->next_rq); |
2647 | |
2648 | pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); |
2649 | BUG_ON(pending); |
2650 | } |
2651 | EXPORT_SYMBOL(__blk_end_request_all); |
2652 | |
2653 | /** |
2654 | * __blk_end_request_cur - Helper function to finish the current request chunk. |
2655 | * @rq: the request to finish the current chunk for |
2656 | * @error: %0 for success, < %0 for error |
2657 | * |
2658 | * Description: |
2659 | * Complete the current consecutively mapped chunk from @rq. Must |
2660 | * be called with queue lock held. |
2661 | * |
2662 | * Return: |
2663 | * %false - we are done with this request |
2664 | * %true - still buffers pending for this request |
2665 | */ |
2666 | bool __blk_end_request_cur(struct request *rq, int error) |
2667 | { |
2668 | return __blk_end_request(rq, error, blk_rq_cur_bytes(rq)); |
2669 | } |
2670 | EXPORT_SYMBOL(__blk_end_request_cur); |
2671 | |
2672 | /** |
2673 | * __blk_end_request_err - Finish a request till the next failure boundary. |
2674 | * @rq: the request to finish till the next failure boundary for |
2675 | * @error: must be negative errno |
2676 | * |
2677 | * Description: |
2678 | * Complete @rq till the next failure boundary. Must be called |
2679 | * with queue lock held. |
2680 | * |
2681 | * Return: |
2682 | * %false - we are done with this request |
2683 | * %true - still buffers pending for this request |
2684 | */ |
2685 | bool __blk_end_request_err(struct request *rq, int error) |
2686 | { |
2687 | WARN_ON(error >= 0); |
2688 | return __blk_end_request(rq, error, blk_rq_err_bytes(rq)); |
2689 | } |
2690 | EXPORT_SYMBOL_GPL(__blk_end_request_err); |
2691 | |
2692 | void blk_rq_bio_prep(struct request_queue *q, struct request *rq, |
2693 | struct bio *bio) |
2694 | { |
2695 | /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */ |
2696 | rq->cmd_flags |= bio->bi_rw & REQ_WRITE; |
2697 | |
2698 | if (bio_has_data(bio)) { |
2699 | rq->nr_phys_segments = bio_phys_segments(q, bio); |
2700 | rq->buffer = bio_data(bio); |
2701 | } |
2702 | rq->__data_len = bio->bi_size; |
2703 | rq->bio = rq->biotail = bio; |
2704 | |
2705 | if (bio->bi_bdev) |
2706 | rq->rq_disk = bio->bi_bdev->bd_disk; |
2707 | } |
2708 | |
2709 | #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE |
2710 | /** |
2711 | * rq_flush_dcache_pages - Helper function to flush all pages in a request |
2712 | * @rq: the request to be flushed |
2713 | * |
2714 | * Description: |
2715 | * Flush all pages in @rq. |
2716 | */ |
2717 | void rq_flush_dcache_pages(struct request *rq) |
2718 | { |
2719 | struct req_iterator iter; |
2720 | struct bio_vec *bvec; |
2721 | |
2722 | rq_for_each_segment(bvec, rq, iter) |
2723 | flush_dcache_page(bvec->bv_page); |
2724 | } |
2725 | EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); |
2726 | #endif |
2727 | |
2728 | /** |
2729 | * blk_lld_busy - Check if underlying low-level drivers of a device are busy |
2730 | * @q : the queue of the device being checked |
2731 | * |
2732 | * Description: |
2733 | * Check if underlying low-level drivers of a device are busy. |
2734 | * If the drivers want to export their busy state, they must set own |
2735 | * exporting function using blk_queue_lld_busy() first. |
2736 | * |
2737 | * Basically, this function is used only by request stacking drivers |
2738 | * to stop dispatching requests to underlying devices when underlying |
2739 | * devices are busy. This behavior helps more I/O merging on the queue |
2740 | * of the request stacking driver and prevents I/O throughput regression |
2741 | * on burst I/O load. |
2742 | * |
2743 | * Return: |
2744 | * 0 - Not busy (The request stacking driver should dispatch request) |
2745 | * 1 - Busy (The request stacking driver should stop dispatching request) |
2746 | */ |
2747 | int blk_lld_busy(struct request_queue *q) |
2748 | { |
2749 | if (q->lld_busy_fn) |
2750 | return q->lld_busy_fn(q); |
2751 | |
2752 | return 0; |
2753 | } |
2754 | EXPORT_SYMBOL_GPL(blk_lld_busy); |
2755 | |
2756 | /** |
2757 | * blk_rq_unprep_clone - Helper function to free all bios in a cloned request |
2758 | * @rq: the clone request to be cleaned up |
2759 | * |
2760 | * Description: |
2761 | * Free all bios in @rq for a cloned request. |
2762 | */ |
2763 | void blk_rq_unprep_clone(struct request *rq) |
2764 | { |
2765 | struct bio *bio; |
2766 | |
2767 | while ((bio = rq->bio) != NULL) { |
2768 | rq->bio = bio->bi_next; |
2769 | |
2770 | bio_put(bio); |
2771 | } |
2772 | } |
2773 | EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); |
2774 | |
2775 | /* |
2776 | * Copy attributes of the original request to the clone request. |
2777 | * The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied. |
2778 | */ |
2779 | static void __blk_rq_prep_clone(struct request *dst, struct request *src) |
2780 | { |
2781 | dst->cpu = src->cpu; |
2782 | dst->cmd_flags = (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE; |
2783 | dst->cmd_type = src->cmd_type; |
2784 | dst->__sector = blk_rq_pos(src); |
2785 | dst->__data_len = blk_rq_bytes(src); |
2786 | dst->nr_phys_segments = src->nr_phys_segments; |
2787 | dst->ioprio = src->ioprio; |
2788 | dst->extra_len = src->extra_len; |
2789 | } |
2790 | |
2791 | /** |
2792 | * blk_rq_prep_clone - Helper function to setup clone request |
2793 | * @rq: the request to be setup |
2794 | * @rq_src: original request to be cloned |
2795 | * @bs: bio_set that bios for clone are allocated from |
2796 | * @gfp_mask: memory allocation mask for bio |
2797 | * @bio_ctr: setup function to be called for each clone bio. |
2798 | * Returns %0 for success, non %0 for failure. |
2799 | * @data: private data to be passed to @bio_ctr |
2800 | * |
2801 | * Description: |
2802 | * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. |
2803 | * The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense) |
2804 | * are not copied, and copying such parts is the caller's responsibility. |
2805 | * Also, pages which the original bios are pointing to are not copied |
2806 | * and the cloned bios just point same pages. |
2807 | * So cloned bios must be completed before original bios, which means |
2808 | * the caller must complete @rq before @rq_src. |
2809 | */ |
2810 | int blk_rq_prep_clone(struct request *rq, struct request *rq_src, |
2811 | struct bio_set *bs, gfp_t gfp_mask, |
2812 | int (*bio_ctr)(struct bio *, struct bio *, void *), |
2813 | void *data) |
2814 | { |
2815 | struct bio *bio, *bio_src; |
2816 | |
2817 | if (!bs) |
2818 | bs = fs_bio_set; |
2819 | |
2820 | blk_rq_init(NULL, rq); |
2821 | |
2822 | __rq_for_each_bio(bio_src, rq_src) { |
2823 | bio = bio_clone_bioset(bio_src, gfp_mask, bs); |
2824 | if (!bio) |
2825 | goto free_and_out; |
2826 | |
2827 | if (bio_ctr && bio_ctr(bio, bio_src, data)) |
2828 | goto free_and_out; |
2829 | |
2830 | if (rq->bio) { |
2831 | rq->biotail->bi_next = bio; |
2832 | rq->biotail = bio; |
2833 | } else |
2834 | rq->bio = rq->biotail = bio; |
2835 | } |
2836 | |
2837 | __blk_rq_prep_clone(rq, rq_src); |
2838 | |
2839 | return 0; |
2840 | |
2841 | free_and_out: |
2842 | if (bio) |
2843 | bio_put(bio); |
2844 | blk_rq_unprep_clone(rq); |
2845 | |
2846 | return -ENOMEM; |
2847 | } |
2848 | EXPORT_SYMBOL_GPL(blk_rq_prep_clone); |
2849 | |
2850 | int kblockd_schedule_work(struct request_queue *q, struct work_struct *work) |
2851 | { |
2852 | return queue_work(kblockd_workqueue, work); |
2853 | } |
2854 | EXPORT_SYMBOL(kblockd_schedule_work); |
2855 | |
2856 | int kblockd_schedule_delayed_work(struct request_queue *q, |
2857 | struct delayed_work *dwork, unsigned long delay) |
2858 | { |
2859 | return queue_delayed_work(kblockd_workqueue, dwork, delay); |
2860 | } |
2861 | EXPORT_SYMBOL(kblockd_schedule_delayed_work); |
2862 | |
2863 | #define PLUG_MAGIC 0x91827364 |
2864 | |
2865 | /** |
2866 | * blk_start_plug - initialize blk_plug and track it inside the task_struct |
2867 | * @plug: The &struct blk_plug that needs to be initialized |
2868 | * |
2869 | * Description: |
2870 | * Tracking blk_plug inside the task_struct will help with auto-flushing the |
2871 | * pending I/O should the task end up blocking between blk_start_plug() and |
2872 | * blk_finish_plug(). This is important from a performance perspective, but |
2873 | * also ensures that we don't deadlock. For instance, if the task is blocking |
2874 | * for a memory allocation, memory reclaim could end up wanting to free a |
2875 | * page belonging to that request that is currently residing in our private |
2876 | * plug. By flushing the pending I/O when the process goes to sleep, we avoid |
2877 | * this kind of deadlock. |
2878 | */ |
2879 | void blk_start_plug(struct blk_plug *plug) |
2880 | { |
2881 | struct task_struct *tsk = current; |
2882 | |
2883 | plug->magic = PLUG_MAGIC; |
2884 | INIT_LIST_HEAD(&plug->list); |
2885 | INIT_LIST_HEAD(&plug->cb_list); |
2886 | |
2887 | /* |
2888 | * If this is a nested plug, don't actually assign it. It will be |
2889 | * flushed on its own. |
2890 | */ |
2891 | if (!tsk->plug) { |
2892 | /* |
2893 | * Store ordering should not be needed here, since a potential |
2894 | * preempt will imply a full memory barrier |
2895 | */ |
2896 | tsk->plug = plug; |
2897 | } |
2898 | } |
2899 | EXPORT_SYMBOL(blk_start_plug); |
2900 | |
2901 | static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b) |
2902 | { |
2903 | struct request *rqa = container_of(a, struct request, queuelist); |
2904 | struct request *rqb = container_of(b, struct request, queuelist); |
2905 | |
2906 | return !(rqa->q < rqb->q || |
2907 | (rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb))); |
2908 | } |
2909 | |
2910 | /* |
2911 | * If 'from_schedule' is true, then postpone the dispatch of requests |
2912 | * until a safe kblockd context. We due this to avoid accidental big |
2913 | * additional stack usage in driver dispatch, in places where the originally |
2914 | * plugger did not intend it. |
2915 | */ |
2916 | static void queue_unplugged(struct request_queue *q, unsigned int depth, |
2917 | bool from_schedule) |
2918 | __releases(q->queue_lock) |
2919 | { |
2920 | trace_block_unplug(q, depth, !from_schedule); |
2921 | |
2922 | if (from_schedule) |
2923 | blk_run_queue_async(q); |
2924 | else |
2925 | __blk_run_queue(q); |
2926 | spin_unlock(q->queue_lock); |
2927 | } |
2928 | |
2929 | static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) |
2930 | { |
2931 | LIST_HEAD(callbacks); |
2932 | |
2933 | while (!list_empty(&plug->cb_list)) { |
2934 | list_splice_init(&plug->cb_list, &callbacks); |
2935 | |
2936 | while (!list_empty(&callbacks)) { |
2937 | struct blk_plug_cb *cb = list_first_entry(&callbacks, |
2938 | struct blk_plug_cb, |
2939 | list); |
2940 | list_del(&cb->list); |
2941 | cb->callback(cb, from_schedule); |
2942 | } |
2943 | } |
2944 | } |
2945 | |
2946 | struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, |
2947 | int size) |
2948 | { |
2949 | struct blk_plug *plug = current->plug; |
2950 | struct blk_plug_cb *cb; |
2951 | |
2952 | if (!plug) |
2953 | return NULL; |
2954 | |
2955 | list_for_each_entry(cb, &plug->cb_list, list) |
2956 | if (cb->callback == unplug && cb->data == data) |
2957 | return cb; |
2958 | |
2959 | /* Not currently on the callback list */ |
2960 | BUG_ON(size < sizeof(*cb)); |
2961 | cb = kzalloc(size, GFP_ATOMIC); |
2962 | if (cb) { |
2963 | cb->data = data; |
2964 | cb->callback = unplug; |
2965 | list_add(&cb->list, &plug->cb_list); |
2966 | } |
2967 | return cb; |
2968 | } |
2969 | EXPORT_SYMBOL(blk_check_plugged); |
2970 | |
2971 | void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) |
2972 | { |
2973 | struct request_queue *q; |
2974 | unsigned long flags; |
2975 | struct request *rq; |
2976 | LIST_HEAD(list); |
2977 | unsigned int depth; |
2978 | |
2979 | BUG_ON(plug->magic != PLUG_MAGIC); |
2980 | |
2981 | flush_plug_callbacks(plug, from_schedule); |
2982 | if (list_empty(&plug->list)) |
2983 | return; |
2984 | |
2985 | list_splice_init(&plug->list, &list); |
2986 | |
2987 | list_sort(NULL, &list, plug_rq_cmp); |
2988 | |
2989 | q = NULL; |
2990 | depth = 0; |
2991 | |
2992 | /* |
2993 | * Save and disable interrupts here, to avoid doing it for every |
2994 | * queue lock we have to take. |
2995 | */ |
2996 | local_irq_save(flags); |
2997 | while (!list_empty(&list)) { |
2998 | rq = list_entry_rq(list.next); |
2999 | list_del_init(&rq->queuelist); |
3000 | BUG_ON(!rq->q); |
3001 | if (rq->q != q) { |
3002 | /* |
3003 | * This drops the queue lock |
3004 | */ |
3005 | if (q) |
3006 | queue_unplugged(q, depth, from_schedule); |
3007 | q = rq->q; |
3008 | depth = 0; |
3009 | spin_lock(q->queue_lock); |
3010 | } |
3011 | |
3012 | /* |
3013 | * Short-circuit if @q is dead |
3014 | */ |
3015 | if (unlikely(blk_queue_dying(q))) { |
3016 | __blk_end_request_all(rq, -ENODEV); |
3017 | continue; |
3018 | } |
3019 | |
3020 | /* |
3021 | * rq is already accounted, so use raw insert |
3022 | */ |
3023 | if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) |
3024 | __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH); |
3025 | else |
3026 | __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE); |
3027 | |
3028 | depth++; |
3029 | } |
3030 | |
3031 | /* |
3032 | * This drops the queue lock |
3033 | */ |
3034 | if (q) |
3035 | queue_unplugged(q, depth, from_schedule); |
3036 | |
3037 | local_irq_restore(flags); |
3038 | } |
3039 | |
3040 | void blk_finish_plug(struct blk_plug *plug) |
3041 | { |
3042 | blk_flush_plug_list(plug, false); |
3043 | |
3044 | if (plug == current->plug) |
3045 | current->plug = NULL; |
3046 | } |
3047 | EXPORT_SYMBOL(blk_finish_plug); |
3048 | |
3049 | int __init blk_dev_init(void) |
3050 | { |
3051 | BUILD_BUG_ON(__REQ_NR_BITS > 8 * |
3052 | sizeof(((struct request *)0)->cmd_flags)); |
3053 | |
3054 | /* used for unplugging and affects IO latency/throughput - HIGHPRI */ |
3055 | kblockd_workqueue = alloc_workqueue("kblockd", |
3056 | WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); |
3057 | if (!kblockd_workqueue) |
3058 | panic("Failed to create kblockd\n"); |
3059 | |
3060 | request_cachep = kmem_cache_create("blkdev_requests", |
3061 | sizeof(struct request), 0, SLAB_PANIC, NULL); |
3062 | |
3063 | blk_requestq_cachep = kmem_cache_create("blkdev_queue", |
3064 | sizeof(struct request_queue), 0, SLAB_PANIC, NULL); |
3065 | |
3066 | return 0; |
3067 | } |
3068 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9