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