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1 /*
2  * Copyright (C) 1991, 1992 Linus Torvalds
3  * Copyright (C) 1994,      Karl Keyte: Added support for disk statistics
4  * Elevator latency, (C) 2000  Andrea Arcangeli <andrea@suse.de> SuSE
5  * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de>
6  * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au>
7  *	-  July2000
8  * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
9  */
10 
11 /*
12  * This handles all read/write requests to block devices
13  */
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/backing-dev.h>
17 #include <linux/bio.h>
18 #include <linux/blkdev.h>
19 #include <linux/blk-mq.h>
20 #include <linux/highmem.h>
21 #include <linux/mm.h>
22 #include <linux/kernel_stat.h>
23 #include <linux/string.h>
24 #include <linux/init.h>
25 #include <linux/completion.h>
26 #include <linux/slab.h>
27 #include <linux/swap.h>
28 #include <linux/writeback.h>
29 #include <linux/task_io_accounting_ops.h>
30 #include <linux/fault-inject.h>
31 #include <linux/list_sort.h>
32 #include <linux/delay.h>
33 #include <linux/ratelimit.h>
34 #include <linux/pm_runtime.h>
35 
36 #define CREATE_TRACE_POINTS
37 #include <trace/events/block.h>
38 
39 #include "blk.h"
40 #include "blk-cgroup.h"
41 #include "blk-mq.h"
42 
43 #include <linux/math64.h>
44 
45 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
46 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
47 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
48 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split);
49 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
50 
51 DEFINE_IDA(blk_queue_ida);
52 
53 /*
54  * For the allocated request tables
55  */
56 struct kmem_cache *request_cachep = NULL;
57 
58 /*
59  * For queue allocation
60  */
61 struct kmem_cache *blk_requestq_cachep;
62 
63 /*
64  * Controlling structure to kblockd
65  */
66 static struct workqueue_struct *kblockd_workqueue;
67 
blk_queue_congestion_threshold(struct request_queue * q)68 void blk_queue_congestion_threshold(struct request_queue *q)
69 {
70 	int nr;
71 
72 	nr = q->nr_requests - (q->nr_requests / 8) + 1;
73 	if (nr > q->nr_requests)
74 		nr = q->nr_requests;
75 	q->nr_congestion_on = nr;
76 
77 	nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
78 	if (nr < 1)
79 		nr = 1;
80 	q->nr_congestion_off = nr;
81 }
82 
83 /**
84  * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
85  * @bdev:	device
86  *
87  * Locates the passed device's request queue and returns the address of its
88  * backing_dev_info.  This function can only be called if @bdev is opened
89  * and the return value is never NULL.
90  */
blk_get_backing_dev_info(struct block_device * bdev)91 struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
92 {
93 	struct request_queue *q = bdev_get_queue(bdev);
94 
95 	return &q->backing_dev_info;
96 }
97 EXPORT_SYMBOL(blk_get_backing_dev_info);
98 
blk_rq_init(struct request_queue * q,struct request * rq)99 void blk_rq_init(struct request_queue *q, struct request *rq)
100 {
101 	memset(rq, 0, sizeof(*rq));
102 
103 	INIT_LIST_HEAD(&rq->queuelist);
104 	INIT_LIST_HEAD(&rq->timeout_list);
105 	rq->cpu = -1;
106 	rq->q = q;
107 	rq->__sector = (sector_t) -1;
108 	INIT_HLIST_NODE(&rq->hash);
109 	RB_CLEAR_NODE(&rq->rb_node);
110 	rq->cmd = rq->__cmd;
111 	rq->cmd_len = BLK_MAX_CDB;
112 	rq->tag = -1;
113 	rq->start_time = jiffies;
114 	set_start_time_ns(rq);
115 	rq->part = NULL;
116 }
117 EXPORT_SYMBOL(blk_rq_init);
118 
req_bio_endio(struct request * rq,struct bio * bio,unsigned int nbytes,int error)119 static void req_bio_endio(struct request *rq, struct bio *bio,
120 			  unsigned int nbytes, int error)
121 {
122 	if (error)
123 		clear_bit(BIO_UPTODATE, &bio->bi_flags);
124 	else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
125 		error = -EIO;
126 
127 	if (unlikely(rq->cmd_flags & REQ_QUIET))
128 		set_bit(BIO_QUIET, &bio->bi_flags);
129 
130 	bio_advance(bio, nbytes);
131 
132 	/* don't actually finish bio if it's part of flush sequence */
133 	if (bio->bi_iter.bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ))
134 		bio_endio(bio, error);
135 }
136 
blk_dump_rq_flags(struct request * rq,char * msg)137 void blk_dump_rq_flags(struct request *rq, char *msg)
138 {
139 	int bit;
140 
141 	printk(KERN_INFO "%s: dev %s: type=%x, flags=%llx\n", msg,
142 		rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
143 		(unsigned long long) rq->cmd_flags);
144 
145 	printk(KERN_INFO "  sector %llu, nr/cnr %u/%u\n",
146 	       (unsigned long long)blk_rq_pos(rq),
147 	       blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
148 	printk(KERN_INFO "  bio %p, biotail %p, len %u\n",
149 	       rq->bio, rq->biotail, blk_rq_bytes(rq));
150 
151 	if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
152 		printk(KERN_INFO "  cdb: ");
153 		for (bit = 0; bit < BLK_MAX_CDB; bit++)
154 			printk("%02x ", rq->cmd[bit]);
155 		printk("\n");
156 	}
157 }
158 EXPORT_SYMBOL(blk_dump_rq_flags);
159 
blk_delay_work(struct work_struct * work)160 static void blk_delay_work(struct work_struct *work)
161 {
162 	struct request_queue *q;
163 
164 	q = container_of(work, struct request_queue, delay_work.work);
165 	spin_lock_irq(q->queue_lock);
166 	__blk_run_queue(q);
167 	spin_unlock_irq(q->queue_lock);
168 }
169 
170 /**
171  * blk_delay_queue - restart queueing after defined interval
172  * @q:		The &struct request_queue in question
173  * @msecs:	Delay in msecs
174  *
175  * Description:
176  *   Sometimes queueing needs to be postponed for a little while, to allow
177  *   resources to come back. This function will make sure that queueing is
178  *   restarted around the specified time. Queue lock must be held.
179  */
blk_delay_queue(struct request_queue * q,unsigned long msecs)180 void blk_delay_queue(struct request_queue *q, unsigned long msecs)
181 {
182 	if (likely(!blk_queue_dead(q)))
183 		queue_delayed_work(kblockd_workqueue, &q->delay_work,
184 				   msecs_to_jiffies(msecs));
185 }
186 EXPORT_SYMBOL(blk_delay_queue);
187 
188 /**
189  * blk_start_queue - restart a previously stopped queue
190  * @q:    The &struct request_queue in question
191  *
192  * Description:
193  *   blk_start_queue() will clear the stop flag on the queue, and call
194  *   the request_fn for the queue if it was in a stopped state when
195  *   entered. Also see blk_stop_queue(). Queue lock must be held.
196  **/
blk_start_queue(struct request_queue * q)197 void blk_start_queue(struct request_queue *q)
198 {
199 	WARN_ON(!in_interrupt() && !irqs_disabled());
200 
201 	queue_flag_clear(QUEUE_FLAG_STOPPED, q);
202 	__blk_run_queue(q);
203 }
204 EXPORT_SYMBOL(blk_start_queue);
205 
206 /**
207  * blk_stop_queue - stop a queue
208  * @q:    The &struct request_queue in question
209  *
210  * Description:
211  *   The Linux block layer assumes that a block driver will consume all
212  *   entries on the request queue when the request_fn strategy is called.
213  *   Often this will not happen, because of hardware limitations (queue
214  *   depth settings). If a device driver gets a 'queue full' response,
215  *   or if it simply chooses not to queue more I/O at one point, it can
216  *   call this function to prevent the request_fn from being called until
217  *   the driver has signalled it's ready to go again. This happens by calling
218  *   blk_start_queue() to restart queue operations. Queue lock must be held.
219  **/
blk_stop_queue(struct request_queue * q)220 void blk_stop_queue(struct request_queue *q)
221 {
222 	cancel_delayed_work(&q->delay_work);
223 	queue_flag_set(QUEUE_FLAG_STOPPED, q);
224 }
225 EXPORT_SYMBOL(blk_stop_queue);
226 
227 /**
228  * blk_sync_queue - cancel any pending callbacks on a queue
229  * @q: the queue
230  *
231  * Description:
232  *     The block layer may perform asynchronous callback activity
233  *     on a queue, such as calling the unplug function after a timeout.
234  *     A block device may call blk_sync_queue to ensure that any
235  *     such activity is cancelled, thus allowing it to release resources
236  *     that the callbacks might use. The caller must already have made sure
237  *     that its ->make_request_fn will not re-add plugging prior to calling
238  *     this function.
239  *
240  *     This function does not cancel any asynchronous activity arising
241  *     out of elevator or throttling code. That would require elevator_exit()
242  *     and blkcg_exit_queue() to be called with queue lock initialized.
243  *
244  */
blk_sync_queue(struct request_queue * q)245 void blk_sync_queue(struct request_queue *q)
246 {
247 	del_timer_sync(&q->timeout);
248 
249 	if (q->mq_ops) {
250 		struct blk_mq_hw_ctx *hctx;
251 		int i;
252 
253 		queue_for_each_hw_ctx(q, hctx, i) {
254 			cancel_delayed_work_sync(&hctx->run_work);
255 			cancel_delayed_work_sync(&hctx->delay_work);
256 		}
257 	} else {
258 		cancel_delayed_work_sync(&q->delay_work);
259 	}
260 }
261 EXPORT_SYMBOL(blk_sync_queue);
262 
263 /**
264  * __blk_run_queue_uncond - run a queue whether or not it has been stopped
265  * @q:	The queue to run
266  *
267  * Description:
268  *    Invoke request handling on a queue if there are any pending requests.
269  *    May be used to restart request handling after a request has completed.
270  *    This variant runs the queue whether or not the queue has been
271  *    stopped. Must be called with the queue lock held and interrupts
272  *    disabled. See also @blk_run_queue.
273  */
__blk_run_queue_uncond(struct request_queue * q)274 inline void __blk_run_queue_uncond(struct request_queue *q)
275 {
276 	if (unlikely(blk_queue_dead(q)))
277 		return;
278 
279 	/*
280 	 * Some request_fn implementations, e.g. scsi_request_fn(), unlock
281 	 * the queue lock internally. As a result multiple threads may be
282 	 * running such a request function concurrently. Keep track of the
283 	 * number of active request_fn invocations such that blk_drain_queue()
284 	 * can wait until all these request_fn calls have finished.
285 	 */
286 	q->request_fn_active++;
287 	q->request_fn(q);
288 	q->request_fn_active--;
289 }
290 
291 /**
292  * __blk_run_queue - run a single device queue
293  * @q:	The queue to run
294  *
295  * Description:
296  *    See @blk_run_queue. This variant must be called with the queue lock
297  *    held and interrupts disabled.
298  */
__blk_run_queue(struct request_queue * q)299 void __blk_run_queue(struct request_queue *q)
300 {
301 	if (unlikely(blk_queue_stopped(q)))
302 		return;
303 
304 	__blk_run_queue_uncond(q);
305 }
306 EXPORT_SYMBOL(__blk_run_queue);
307 
308 /**
309  * blk_run_queue_async - run a single device queue in workqueue context
310  * @q:	The queue to run
311  *
312  * Description:
313  *    Tells kblockd to perform the equivalent of @blk_run_queue on behalf
314  *    of us. The caller must hold the queue lock.
315  */
blk_run_queue_async(struct request_queue * q)316 void blk_run_queue_async(struct request_queue *q)
317 {
318 	if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q)))
319 		mod_delayed_work(kblockd_workqueue, &q->delay_work, 0);
320 }
321 EXPORT_SYMBOL(blk_run_queue_async);
322 
323 /**
324  * blk_run_queue - run a single device queue
325  * @q: The queue to run
326  *
327  * Description:
328  *    Invoke request handling on this queue, if it has pending work to do.
329  *    May be used to restart queueing when a request has completed.
330  */
blk_run_queue(struct request_queue * q)331 void blk_run_queue(struct request_queue *q)
332 {
333 	unsigned long flags;
334 
335 	spin_lock_irqsave(q->queue_lock, flags);
336 	__blk_run_queue(q);
337 	spin_unlock_irqrestore(q->queue_lock, flags);
338 }
339 EXPORT_SYMBOL(blk_run_queue);
340 
blk_put_queue(struct request_queue * q)341 void blk_put_queue(struct request_queue *q)
342 {
343 	kobject_put(&q->kobj);
344 }
345 EXPORT_SYMBOL(blk_put_queue);
346 
347 /**
348  * __blk_drain_queue - drain requests from request_queue
349  * @q: queue to drain
350  * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
351  *
352  * Drain requests from @q.  If @drain_all is set, all requests are drained.
353  * If not, only ELVPRIV requests are drained.  The caller is responsible
354  * for ensuring that no new requests which need to be drained are queued.
355  */
__blk_drain_queue(struct request_queue * q,bool drain_all)356 static void __blk_drain_queue(struct request_queue *q, bool drain_all)
357 	__releases(q->queue_lock)
358 	__acquires(q->queue_lock)
359 {
360 	int i;
361 
362 	lockdep_assert_held(q->queue_lock);
363 
364 	while (true) {
365 		bool drain = false;
366 
367 		/*
368 		 * The caller might be trying to drain @q before its
369 		 * elevator is initialized.
370 		 */
371 		if (q->elevator)
372 			elv_drain_elevator(q);
373 
374 		blkcg_drain_queue(q);
375 
376 		/*
377 		 * This function might be called on a queue which failed
378 		 * driver init after queue creation or is not yet fully
379 		 * active yet.  Some drivers (e.g. fd and loop) get unhappy
380 		 * in such cases.  Kick queue iff dispatch queue has
381 		 * something on it and @q has request_fn set.
382 		 */
383 		if (!list_empty(&q->queue_head) && q->request_fn)
384 			__blk_run_queue(q);
385 
386 		drain |= q->nr_rqs_elvpriv;
387 		drain |= q->request_fn_active;
388 
389 		/*
390 		 * Unfortunately, requests are queued at and tracked from
391 		 * multiple places and there's no single counter which can
392 		 * be drained.  Check all the queues and counters.
393 		 */
394 		if (drain_all) {
395 			struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
396 			drain |= !list_empty(&q->queue_head);
397 			for (i = 0; i < 2; i++) {
398 				drain |= q->nr_rqs[i];
399 				drain |= q->in_flight[i];
400 				if (fq)
401 				    drain |= !list_empty(&fq->flush_queue[i]);
402 			}
403 		}
404 
405 		if (!drain)
406 			break;
407 
408 		spin_unlock_irq(q->queue_lock);
409 
410 		msleep(10);
411 
412 		spin_lock_irq(q->queue_lock);
413 	}
414 
415 	/*
416 	 * With queue marked dead, any woken up waiter will fail the
417 	 * allocation path, so the wakeup chaining is lost and we're
418 	 * left with hung waiters. We need to wake up those waiters.
419 	 */
420 	if (q->request_fn) {
421 		struct request_list *rl;
422 
423 		blk_queue_for_each_rl(rl, q)
424 			for (i = 0; i < ARRAY_SIZE(rl->wait); i++)
425 				wake_up_all(&rl->wait[i]);
426 	}
427 }
428 
429 /**
430  * blk_queue_bypass_start - enter queue bypass mode
431  * @q: queue of interest
432  *
433  * In bypass mode, only the dispatch FIFO queue of @q is used.  This
434  * function makes @q enter bypass mode and drains all requests which were
435  * throttled or issued before.  On return, it's guaranteed that no request
436  * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
437  * inside queue or RCU read lock.
438  */
blk_queue_bypass_start(struct request_queue * q)439 void blk_queue_bypass_start(struct request_queue *q)
440 {
441 	spin_lock_irq(q->queue_lock);
442 	q->bypass_depth++;
443 	queue_flag_set(QUEUE_FLAG_BYPASS, q);
444 	spin_unlock_irq(q->queue_lock);
445 
446 	/*
447 	 * Queues start drained.  Skip actual draining till init is
448 	 * complete.  This avoids lenghty delays during queue init which
449 	 * can happen many times during boot.
450 	 */
451 	if (blk_queue_init_done(q)) {
452 		spin_lock_irq(q->queue_lock);
453 		__blk_drain_queue(q, false);
454 		spin_unlock_irq(q->queue_lock);
455 
456 		/* ensure blk_queue_bypass() is %true inside RCU read lock */
457 		synchronize_rcu();
458 	}
459 }
460 EXPORT_SYMBOL_GPL(blk_queue_bypass_start);
461 
462 /**
463  * blk_queue_bypass_end - leave queue bypass mode
464  * @q: queue of interest
465  *
466  * Leave bypass mode and restore the normal queueing behavior.
467  */
blk_queue_bypass_end(struct request_queue * q)468 void blk_queue_bypass_end(struct request_queue *q)
469 {
470 	spin_lock_irq(q->queue_lock);
471 	if (!--q->bypass_depth)
472 		queue_flag_clear(QUEUE_FLAG_BYPASS, q);
473 	WARN_ON_ONCE(q->bypass_depth < 0);
474 	spin_unlock_irq(q->queue_lock);
475 }
476 EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
477 
478 /**
479  * blk_cleanup_queue - shutdown a request queue
480  * @q: request queue to shutdown
481  *
482  * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
483  * put it.  All future requests will be failed immediately with -ENODEV.
484  */
blk_cleanup_queue(struct request_queue * q)485 void blk_cleanup_queue(struct request_queue *q)
486 {
487 	spinlock_t *lock = q->queue_lock;
488 
489 	/* mark @q DYING, no new request or merges will be allowed afterwards */
490 	mutex_lock(&q->sysfs_lock);
491 	queue_flag_set_unlocked(QUEUE_FLAG_DYING, q);
492 	spin_lock_irq(lock);
493 
494 	/*
495 	 * A dying queue is permanently in bypass mode till released.  Note
496 	 * that, unlike blk_queue_bypass_start(), we aren't performing
497 	 * synchronize_rcu() after entering bypass mode to avoid the delay
498 	 * as some drivers create and destroy a lot of queues while
499 	 * probing.  This is still safe because blk_release_queue() will be
500 	 * called only after the queue refcnt drops to zero and nothing,
501 	 * RCU or not, would be traversing the queue by then.
502 	 */
503 	q->bypass_depth++;
504 	queue_flag_set(QUEUE_FLAG_BYPASS, q);
505 
506 	queue_flag_set(QUEUE_FLAG_NOMERGES, q);
507 	queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
508 	queue_flag_set(QUEUE_FLAG_DYING, q);
509 	spin_unlock_irq(lock);
510 	mutex_unlock(&q->sysfs_lock);
511 
512 	/*
513 	 * Drain all requests queued before DYING marking. Set DEAD flag to
514 	 * prevent that q->request_fn() gets invoked after draining finished.
515 	 */
516 	if (q->mq_ops) {
517 		blk_mq_freeze_queue(q);
518 		spin_lock_irq(lock);
519 	} else {
520 		spin_lock_irq(lock);
521 		__blk_drain_queue(q, true);
522 	}
523 	queue_flag_set(QUEUE_FLAG_DEAD, q);
524 	spin_unlock_irq(lock);
525 
526 	/* @q won't process any more request, flush async actions */
527 	del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
528 	blk_sync_queue(q);
529 
530 	if (q->mq_ops)
531 		blk_mq_free_queue(q);
532 
533 	spin_lock_irq(lock);
534 	if (q->queue_lock != &q->__queue_lock)
535 		q->queue_lock = &q->__queue_lock;
536 	spin_unlock_irq(lock);
537 
538 	/* @q is and will stay empty, shutdown and put */
539 	blk_put_queue(q);
540 }
541 EXPORT_SYMBOL(blk_cleanup_queue);
542 
blk_init_rl(struct request_list * rl,struct request_queue * q,gfp_t gfp_mask)543 int blk_init_rl(struct request_list *rl, struct request_queue *q,
544 		gfp_t gfp_mask)
545 {
546 	if (unlikely(rl->rq_pool))
547 		return 0;
548 
549 	rl->q = q;
550 	rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
551 	rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
552 	init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
553 	init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
554 
555 	rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
556 					  mempool_free_slab, request_cachep,
557 					  gfp_mask, q->node);
558 	if (!rl->rq_pool)
559 		return -ENOMEM;
560 
561 	return 0;
562 }
563 
blk_exit_rl(struct request_list * rl)564 void blk_exit_rl(struct request_list *rl)
565 {
566 	if (rl->rq_pool)
567 		mempool_destroy(rl->rq_pool);
568 }
569 
blk_alloc_queue(gfp_t gfp_mask)570 struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
571 {
572 	return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE);
573 }
574 EXPORT_SYMBOL(blk_alloc_queue);
575 
blk_alloc_queue_node(gfp_t gfp_mask,int node_id)576 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
577 {
578 	struct request_queue *q;
579 	int err;
580 
581 	q = kmem_cache_alloc_node(blk_requestq_cachep,
582 				gfp_mask | __GFP_ZERO, node_id);
583 	if (!q)
584 		return NULL;
585 
586 	q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask);
587 	if (q->id < 0)
588 		goto fail_q;
589 
590 	q->backing_dev_info.ra_pages =
591 			(VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
592 	q->backing_dev_info.state = 0;
593 	q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
594 	q->backing_dev_info.name = "block";
595 	q->node = node_id;
596 
597 	err = bdi_init(&q->backing_dev_info);
598 	if (err)
599 		goto fail_id;
600 
601 	setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
602 		    laptop_mode_timer_fn, (unsigned long) q);
603 	setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
604 	INIT_LIST_HEAD(&q->queue_head);
605 	INIT_LIST_HEAD(&q->timeout_list);
606 	INIT_LIST_HEAD(&q->icq_list);
607 #ifdef CONFIG_BLK_CGROUP
608 	INIT_LIST_HEAD(&q->blkg_list);
609 #endif
610 	INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);
611 
612 	kobject_init(&q->kobj, &blk_queue_ktype);
613 
614 	mutex_init(&q->sysfs_lock);
615 	spin_lock_init(&q->__queue_lock);
616 
617 	/*
618 	 * By default initialize queue_lock to internal lock and driver can
619 	 * override it later if need be.
620 	 */
621 	q->queue_lock = &q->__queue_lock;
622 
623 	/*
624 	 * A queue starts its life with bypass turned on to avoid
625 	 * unnecessary bypass on/off overhead and nasty surprises during
626 	 * init.  The initial bypass will be finished when the queue is
627 	 * registered by blk_register_queue().
628 	 */
629 	q->bypass_depth = 1;
630 	__set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags);
631 
632 	init_waitqueue_head(&q->mq_freeze_wq);
633 
634 	if (blkcg_init_queue(q))
635 		goto fail_bdi;
636 
637 	return q;
638 
639 fail_bdi:
640 	bdi_destroy(&q->backing_dev_info);
641 fail_id:
642 	ida_simple_remove(&blk_queue_ida, q->id);
643 fail_q:
644 	kmem_cache_free(blk_requestq_cachep, q);
645 	return NULL;
646 }
647 EXPORT_SYMBOL(blk_alloc_queue_node);
648 
649 /**
650  * blk_init_queue  - prepare a request queue for use with a block device
651  * @rfn:  The function to be called to process requests that have been
652  *        placed on the queue.
653  * @lock: Request queue spin lock
654  *
655  * Description:
656  *    If a block device wishes to use the standard request handling procedures,
657  *    which sorts requests and coalesces adjacent requests, then it must
658  *    call blk_init_queue().  The function @rfn will be called when there
659  *    are requests on the queue that need to be processed.  If the device
660  *    supports plugging, then @rfn may not be called immediately when requests
661  *    are available on the queue, but may be called at some time later instead.
662  *    Plugged queues are generally unplugged when a buffer belonging to one
663  *    of the requests on the queue is needed, or due to memory pressure.
664  *
665  *    @rfn is not required, or even expected, to remove all requests off the
666  *    queue, but only as many as it can handle at a time.  If it does leave
667  *    requests on the queue, it is responsible for arranging that the requests
668  *    get dealt with eventually.
669  *
670  *    The queue spin lock must be held while manipulating the requests on the
671  *    request queue; this lock will be taken also from interrupt context, so irq
672  *    disabling is needed for it.
673  *
674  *    Function returns a pointer to the initialized request queue, or %NULL if
675  *    it didn't succeed.
676  *
677  * Note:
678  *    blk_init_queue() must be paired with a blk_cleanup_queue() call
679  *    when the block device is deactivated (such as at module unload).
680  **/
681 
blk_init_queue(request_fn_proc * rfn,spinlock_t * lock)682 struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
683 {
684 	return blk_init_queue_node(rfn, lock, NUMA_NO_NODE);
685 }
686 EXPORT_SYMBOL(blk_init_queue);
687 
688 struct request_queue *
blk_init_queue_node(request_fn_proc * rfn,spinlock_t * lock,int node_id)689 blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
690 {
691 	struct request_queue *uninit_q, *q;
692 
693 	uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id);
694 	if (!uninit_q)
695 		return NULL;
696 
697 	q = blk_init_allocated_queue(uninit_q, rfn, lock);
698 	if (!q)
699 		blk_cleanup_queue(uninit_q);
700 
701 	return q;
702 }
703 EXPORT_SYMBOL(blk_init_queue_node);
704 
705 struct request_queue *
blk_init_allocated_queue(struct request_queue * q,request_fn_proc * rfn,spinlock_t * lock)706 blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
707 			 spinlock_t *lock)
708 {
709 	if (!q)
710 		return NULL;
711 
712 	q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, 0);
713 	if (!q->fq)
714 		return NULL;
715 
716 	if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))
717 		goto fail;
718 
719 	q->request_fn		= rfn;
720 	q->prep_rq_fn		= NULL;
721 	q->unprep_rq_fn		= NULL;
722 	q->queue_flags		|= QUEUE_FLAG_DEFAULT;
723 
724 	/* Override internal queue lock with supplied lock pointer */
725 	if (lock)
726 		q->queue_lock		= lock;
727 
728 	/*
729 	 * This also sets hw/phys segments, boundary and size
730 	 */
731 	blk_queue_make_request(q, blk_queue_bio);
732 
733 	q->sg_reserved_size = INT_MAX;
734 
735 	/* Protect q->elevator from elevator_change */
736 	mutex_lock(&q->sysfs_lock);
737 
738 	/* init elevator */
739 	if (elevator_init(q, NULL)) {
740 		mutex_unlock(&q->sysfs_lock);
741 		goto fail;
742 	}
743 
744 	mutex_unlock(&q->sysfs_lock);
745 
746 	return q;
747 
748 fail:
749 	blk_free_flush_queue(q->fq);
750 	return NULL;
751 }
752 EXPORT_SYMBOL(blk_init_allocated_queue);
753 
blk_get_queue(struct request_queue * q)754 bool blk_get_queue(struct request_queue *q)
755 {
756 	if (likely(!blk_queue_dying(q))) {
757 		__blk_get_queue(q);
758 		return true;
759 	}
760 
761 	return false;
762 }
763 EXPORT_SYMBOL(blk_get_queue);
764 
blk_free_request(struct request_list * rl,struct request * rq)765 static inline void blk_free_request(struct request_list *rl, struct request *rq)
766 {
767 	if (rq->cmd_flags & REQ_ELVPRIV) {
768 		elv_put_request(rl->q, rq);
769 		if (rq->elv.icq)
770 			put_io_context(rq->elv.icq->ioc);
771 	}
772 
773 	mempool_free(rq, rl->rq_pool);
774 }
775 
776 /*
777  * ioc_batching returns true if the ioc is a valid batching request and
778  * should be given priority access to a request.
779  */
ioc_batching(struct request_queue * q,struct io_context * ioc)780 static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
781 {
782 	if (!ioc)
783 		return 0;
784 
785 	/*
786 	 * Make sure the process is able to allocate at least 1 request
787 	 * even if the batch times out, otherwise we could theoretically
788 	 * lose wakeups.
789 	 */
790 	return ioc->nr_batch_requests == q->nr_batching ||
791 		(ioc->nr_batch_requests > 0
792 		&& time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
793 }
794 
795 /*
796  * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
797  * will cause the process to be a "batcher" on all queues in the system. This
798  * is the behaviour we want though - once it gets a wakeup it should be given
799  * a nice run.
800  */
ioc_set_batching(struct request_queue * q,struct io_context * ioc)801 static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
802 {
803 	if (!ioc || ioc_batching(q, ioc))
804 		return;
805 
806 	ioc->nr_batch_requests = q->nr_batching;
807 	ioc->last_waited = jiffies;
808 }
809 
__freed_request(struct request_list * rl,int sync)810 static void __freed_request(struct request_list *rl, int sync)
811 {
812 	struct request_queue *q = rl->q;
813 
814 	/*
815 	 * bdi isn't aware of blkcg yet.  As all async IOs end up root
816 	 * blkcg anyway, just use root blkcg state.
817 	 */
818 	if (rl == &q->root_rl &&
819 	    rl->count[sync] < queue_congestion_off_threshold(q))
820 		blk_clear_queue_congested(q, sync);
821 
822 	if (rl->count[sync] + 1 <= q->nr_requests) {
823 		if (waitqueue_active(&rl->wait[sync]))
824 			wake_up(&rl->wait[sync]);
825 
826 		blk_clear_rl_full(rl, sync);
827 	}
828 }
829 
830 /*
831  * A request has just been released.  Account for it, update the full and
832  * congestion status, wake up any waiters.   Called under q->queue_lock.
833  */
freed_request(struct request_list * rl,unsigned int flags)834 static void freed_request(struct request_list *rl, unsigned int flags)
835 {
836 	struct request_queue *q = rl->q;
837 	int sync = rw_is_sync(flags);
838 
839 	q->nr_rqs[sync]--;
840 	rl->count[sync]--;
841 	if (flags & REQ_ELVPRIV)
842 		q->nr_rqs_elvpriv--;
843 
844 	__freed_request(rl, sync);
845 
846 	if (unlikely(rl->starved[sync ^ 1]))
847 		__freed_request(rl, sync ^ 1);
848 }
849 
blk_update_nr_requests(struct request_queue * q,unsigned int nr)850 int blk_update_nr_requests(struct request_queue *q, unsigned int nr)
851 {
852 	struct request_list *rl;
853 
854 	spin_lock_irq(q->queue_lock);
855 	q->nr_requests = nr;
856 	blk_queue_congestion_threshold(q);
857 
858 	/* congestion isn't cgroup aware and follows root blkcg for now */
859 	rl = &q->root_rl;
860 
861 	if (rl->count[BLK_RW_SYNC] >= queue_congestion_on_threshold(q))
862 		blk_set_queue_congested(q, BLK_RW_SYNC);
863 	else if (rl->count[BLK_RW_SYNC] < queue_congestion_off_threshold(q))
864 		blk_clear_queue_congested(q, BLK_RW_SYNC);
865 
866 	if (rl->count[BLK_RW_ASYNC] >= queue_congestion_on_threshold(q))
867 		blk_set_queue_congested(q, BLK_RW_ASYNC);
868 	else if (rl->count[BLK_RW_ASYNC] < queue_congestion_off_threshold(q))
869 		blk_clear_queue_congested(q, BLK_RW_ASYNC);
870 
871 	blk_queue_for_each_rl(rl, q) {
872 		if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
873 			blk_set_rl_full(rl, BLK_RW_SYNC);
874 		} else {
875 			blk_clear_rl_full(rl, BLK_RW_SYNC);
876 			wake_up(&rl->wait[BLK_RW_SYNC]);
877 		}
878 
879 		if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
880 			blk_set_rl_full(rl, BLK_RW_ASYNC);
881 		} else {
882 			blk_clear_rl_full(rl, BLK_RW_ASYNC);
883 			wake_up(&rl->wait[BLK_RW_ASYNC]);
884 		}
885 	}
886 
887 	spin_unlock_irq(q->queue_lock);
888 	return 0;
889 }
890 
891 /*
892  * Determine if elevator data should be initialized when allocating the
893  * request associated with @bio.
894  */
blk_rq_should_init_elevator(struct bio * bio)895 static bool blk_rq_should_init_elevator(struct bio *bio)
896 {
897 	if (!bio)
898 		return true;
899 
900 	/*
901 	 * Flush requests do not use the elevator so skip initialization.
902 	 * This allows a request to share the flush and elevator data.
903 	 */
904 	if (bio->bi_rw & (REQ_FLUSH | REQ_FUA))
905 		return false;
906 
907 	return true;
908 }
909 
910 /**
911  * rq_ioc - determine io_context for request allocation
912  * @bio: request being allocated is for this bio (can be %NULL)
913  *
914  * Determine io_context to use for request allocation for @bio.  May return
915  * %NULL if %current->io_context doesn't exist.
916  */
rq_ioc(struct bio * bio)917 static struct io_context *rq_ioc(struct bio *bio)
918 {
919 #ifdef CONFIG_BLK_CGROUP
920 	if (bio && bio->bi_ioc)
921 		return bio->bi_ioc;
922 #endif
923 	return current->io_context;
924 }
925 
926 /**
927  * __get_request - get a free request
928  * @rl: request list to allocate from
929  * @rw_flags: RW and SYNC flags
930  * @bio: bio to allocate request for (can be %NULL)
931  * @gfp_mask: allocation mask
932  *
933  * Get a free request from @q.  This function may fail under memory
934  * pressure or if @q is dead.
935  *
936  * Must be called with @q->queue_lock held and,
937  * Returns ERR_PTR on failure, with @q->queue_lock held.
938  * Returns request pointer on success, with @q->queue_lock *not held*.
939  */
__get_request(struct request_list * rl,int rw_flags,struct bio * bio,gfp_t gfp_mask)940 static struct request *__get_request(struct request_list *rl, int rw_flags,
941 				     struct bio *bio, gfp_t gfp_mask)
942 {
943 	struct request_queue *q = rl->q;
944 	struct request *rq;
945 	struct elevator_type *et = q->elevator->type;
946 	struct io_context *ioc = rq_ioc(bio);
947 	struct io_cq *icq = NULL;
948 	const bool is_sync = rw_is_sync(rw_flags) != 0;
949 	int may_queue;
950 
951 	if (unlikely(blk_queue_dying(q)))
952 		return ERR_PTR(-ENODEV);
953 
954 	may_queue = elv_may_queue(q, rw_flags);
955 	if (may_queue == ELV_MQUEUE_NO)
956 		goto rq_starved;
957 
958 	if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
959 		if (rl->count[is_sync]+1 >= q->nr_requests) {
960 			/*
961 			 * The queue will fill after this allocation, so set
962 			 * it as full, and mark this process as "batching".
963 			 * This process will be allowed to complete a batch of
964 			 * requests, others will be blocked.
965 			 */
966 			if (!blk_rl_full(rl, is_sync)) {
967 				ioc_set_batching(q, ioc);
968 				blk_set_rl_full(rl, is_sync);
969 			} else {
970 				if (may_queue != ELV_MQUEUE_MUST
971 						&& !ioc_batching(q, ioc)) {
972 					/*
973 					 * The queue is full and the allocating
974 					 * process is not a "batcher", and not
975 					 * exempted by the IO scheduler
976 					 */
977 					return ERR_PTR(-ENOMEM);
978 				}
979 			}
980 		}
981 		/*
982 		 * bdi isn't aware of blkcg yet.  As all async IOs end up
983 		 * root blkcg anyway, just use root blkcg state.
984 		 */
985 		if (rl == &q->root_rl)
986 			blk_set_queue_congested(q, is_sync);
987 	}
988 
989 	/*
990 	 * Only allow batching queuers to allocate up to 50% over the defined
991 	 * limit of requests, otherwise we could have thousands of requests
992 	 * allocated with any setting of ->nr_requests
993 	 */
994 	if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
995 		return ERR_PTR(-ENOMEM);
996 
997 	q->nr_rqs[is_sync]++;
998 	rl->count[is_sync]++;
999 	rl->starved[is_sync] = 0;
1000 
1001 	/*
1002 	 * Decide whether the new request will be managed by elevator.  If
1003 	 * so, mark @rw_flags and increment elvpriv.  Non-zero elvpriv will
1004 	 * prevent the current elevator from being destroyed until the new
1005 	 * request is freed.  This guarantees icq's won't be destroyed and
1006 	 * makes creating new ones safe.
1007 	 *
1008 	 * Also, lookup icq while holding queue_lock.  If it doesn't exist,
1009 	 * it will be created after releasing queue_lock.
1010 	 */
1011 	if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) {
1012 		rw_flags |= REQ_ELVPRIV;
1013 		q->nr_rqs_elvpriv++;
1014 		if (et->icq_cache && ioc)
1015 			icq = ioc_lookup_icq(ioc, q);
1016 	}
1017 
1018 	if (blk_queue_io_stat(q))
1019 		rw_flags |= REQ_IO_STAT;
1020 	spin_unlock_irq(q->queue_lock);
1021 
1022 	/* allocate and init request */
1023 	rq = mempool_alloc(rl->rq_pool, gfp_mask);
1024 	if (!rq)
1025 		goto fail_alloc;
1026 
1027 	blk_rq_init(q, rq);
1028 	blk_rq_set_rl(rq, rl);
1029 	rq->cmd_flags = rw_flags | REQ_ALLOCED;
1030 
1031 	/* init elvpriv */
1032 	if (rw_flags & REQ_ELVPRIV) {
1033 		if (unlikely(et->icq_cache && !icq)) {
1034 			if (ioc)
1035 				icq = ioc_create_icq(ioc, q, gfp_mask);
1036 			if (!icq)
1037 				goto fail_elvpriv;
1038 		}
1039 
1040 		rq->elv.icq = icq;
1041 		if (unlikely(elv_set_request(q, rq, bio, gfp_mask)))
1042 			goto fail_elvpriv;
1043 
1044 		/* @rq->elv.icq holds io_context until @rq is freed */
1045 		if (icq)
1046 			get_io_context(icq->ioc);
1047 	}
1048 out:
1049 	/*
1050 	 * ioc may be NULL here, and ioc_batching will be false. That's
1051 	 * OK, if the queue is under the request limit then requests need
1052 	 * not count toward the nr_batch_requests limit. There will always
1053 	 * be some limit enforced by BLK_BATCH_TIME.
1054 	 */
1055 	if (ioc_batching(q, ioc))
1056 		ioc->nr_batch_requests--;
1057 
1058 	trace_block_getrq(q, bio, rw_flags & 1);
1059 	return rq;
1060 
1061 fail_elvpriv:
1062 	/*
1063 	 * elvpriv init failed.  ioc, icq and elvpriv aren't mempool backed
1064 	 * and may fail indefinitely under memory pressure and thus
1065 	 * shouldn't stall IO.  Treat this request as !elvpriv.  This will
1066 	 * disturb iosched and blkcg but weird is bettern than dead.
1067 	 */
1068 	printk_ratelimited(KERN_WARNING "%s: dev %s: request aux data allocation failed, iosched may be disturbed\n",
1069 			   __func__, dev_name(q->backing_dev_info.dev));
1070 
1071 	rq->cmd_flags &= ~REQ_ELVPRIV;
1072 	rq->elv.icq = NULL;
1073 
1074 	spin_lock_irq(q->queue_lock);
1075 	q->nr_rqs_elvpriv--;
1076 	spin_unlock_irq(q->queue_lock);
1077 	goto out;
1078 
1079 fail_alloc:
1080 	/*
1081 	 * Allocation failed presumably due to memory. Undo anything we
1082 	 * might have messed up.
1083 	 *
1084 	 * Allocating task should really be put onto the front of the wait
1085 	 * queue, but this is pretty rare.
1086 	 */
1087 	spin_lock_irq(q->queue_lock);
1088 	freed_request(rl, rw_flags);
1089 
1090 	/*
1091 	 * in the very unlikely event that allocation failed and no
1092 	 * requests for this direction was pending, mark us starved so that
1093 	 * freeing of a request in the other direction will notice
1094 	 * us. another possible fix would be to split the rq mempool into
1095 	 * READ and WRITE
1096 	 */
1097 rq_starved:
1098 	if (unlikely(rl->count[is_sync] == 0))
1099 		rl->starved[is_sync] = 1;
1100 	return ERR_PTR(-ENOMEM);
1101 }
1102 
1103 /**
1104  * get_request - get a free request
1105  * @q: request_queue to allocate request from
1106  * @rw_flags: RW and SYNC flags
1107  * @bio: bio to allocate request for (can be %NULL)
1108  * @gfp_mask: allocation mask
1109  *
1110  * Get a free request from @q.  If %__GFP_WAIT is set in @gfp_mask, this
1111  * function keeps retrying under memory pressure and fails iff @q is dead.
1112  *
1113  * Must be called with @q->queue_lock held and,
1114  * Returns ERR_PTR on failure, with @q->queue_lock held.
1115  * Returns request pointer on success, with @q->queue_lock *not held*.
1116  */
get_request(struct request_queue * q,int rw_flags,struct bio * bio,gfp_t gfp_mask)1117 static struct request *get_request(struct request_queue *q, int rw_flags,
1118 				   struct bio *bio, gfp_t gfp_mask)
1119 {
1120 	const bool is_sync = rw_is_sync(rw_flags) != 0;
1121 	DEFINE_WAIT(wait);
1122 	struct request_list *rl;
1123 	struct request *rq;
1124 
1125 	rl = blk_get_rl(q, bio);	/* transferred to @rq on success */
1126 retry:
1127 	rq = __get_request(rl, rw_flags, bio, gfp_mask);
1128 	if (!IS_ERR(rq))
1129 		return rq;
1130 
1131 	if (!(gfp_mask & __GFP_WAIT) || unlikely(blk_queue_dying(q))) {
1132 		blk_put_rl(rl);
1133 		return rq;
1134 	}
1135 
1136 	/* wait on @rl and retry */
1137 	prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
1138 				  TASK_UNINTERRUPTIBLE);
1139 
1140 	trace_block_sleeprq(q, bio, rw_flags & 1);
1141 
1142 	spin_unlock_irq(q->queue_lock);
1143 	io_schedule();
1144 
1145 	/*
1146 	 * After sleeping, we become a "batching" process and will be able
1147 	 * to allocate at least one request, and up to a big batch of them
1148 	 * for a small period time.  See ioc_batching, ioc_set_batching
1149 	 */
1150 	ioc_set_batching(q, current->io_context);
1151 
1152 	spin_lock_irq(q->queue_lock);
1153 	finish_wait(&rl->wait[is_sync], &wait);
1154 
1155 	goto retry;
1156 }
1157 
blk_old_get_request(struct request_queue * q,int rw,gfp_t gfp_mask)1158 static struct request *blk_old_get_request(struct request_queue *q, int rw,
1159 		gfp_t gfp_mask)
1160 {
1161 	struct request *rq;
1162 
1163 	BUG_ON(rw != READ && rw != WRITE);
1164 
1165 	/* create ioc upfront */
1166 	create_io_context(gfp_mask, q->node);
1167 
1168 	spin_lock_irq(q->queue_lock);
1169 	rq = get_request(q, rw, NULL, gfp_mask);
1170 	if (IS_ERR(rq))
1171 		spin_unlock_irq(q->queue_lock);
1172 	/* q->queue_lock is unlocked at this point */
1173 
1174 	return rq;
1175 }
1176 
blk_get_request(struct request_queue * q,int rw,gfp_t gfp_mask)1177 struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
1178 {
1179 	if (q->mq_ops)
1180 		return blk_mq_alloc_request(q, rw, gfp_mask, false);
1181 	else
1182 		return blk_old_get_request(q, rw, gfp_mask);
1183 }
1184 EXPORT_SYMBOL(blk_get_request);
1185 
1186 /**
1187  * blk_make_request - given a bio, allocate a corresponding struct request.
1188  * @q: target request queue
1189  * @bio:  The bio describing the memory mappings that will be submitted for IO.
1190  *        It may be a chained-bio properly constructed by block/bio layer.
1191  * @gfp_mask: gfp flags to be used for memory allocation
1192  *
1193  * blk_make_request is the parallel of generic_make_request for BLOCK_PC
1194  * type commands. Where the struct request needs to be farther initialized by
1195  * the caller. It is passed a &struct bio, which describes the memory info of
1196  * the I/O transfer.
1197  *
1198  * The caller of blk_make_request must make sure that bi_io_vec
1199  * are set to describe the memory buffers. That bio_data_dir() will return
1200  * the needed direction of the request. (And all bio's in the passed bio-chain
1201  * are properly set accordingly)
1202  *
1203  * If called under none-sleepable conditions, mapped bio buffers must not
1204  * need bouncing, by calling the appropriate masked or flagged allocator,
1205  * suitable for the target device. Otherwise the call to blk_queue_bounce will
1206  * BUG.
1207  *
1208  * WARNING: When allocating/cloning a bio-chain, careful consideration should be
1209  * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for
1210  * anything but the first bio in the chain. Otherwise you risk waiting for IO
1211  * completion of a bio that hasn't been submitted yet, thus resulting in a
1212  * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead
1213  * of bio_alloc(), as that avoids the mempool deadlock.
1214  * If possible a big IO should be split into smaller parts when allocation
1215  * fails. Partial allocation should not be an error, or you risk a live-lock.
1216  */
blk_make_request(struct request_queue * q,struct bio * bio,gfp_t gfp_mask)1217 struct request *blk_make_request(struct request_queue *q, struct bio *bio,
1218 				 gfp_t gfp_mask)
1219 {
1220 	struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask);
1221 
1222 	if (IS_ERR(rq))
1223 		return rq;
1224 
1225 	blk_rq_set_block_pc(rq);
1226 
1227 	for_each_bio(bio) {
1228 		struct bio *bounce_bio = bio;
1229 		int ret;
1230 
1231 		blk_queue_bounce(q, &bounce_bio);
1232 		ret = blk_rq_append_bio(q, rq, bounce_bio);
1233 		if (unlikely(ret)) {
1234 			blk_put_request(rq);
1235 			return ERR_PTR(ret);
1236 		}
1237 	}
1238 
1239 	return rq;
1240 }
1241 EXPORT_SYMBOL(blk_make_request);
1242 
1243 /**
1244  * blk_rq_set_block_pc - initialize a request to type BLOCK_PC
1245  * @rq:		request to be initialized
1246  *
1247  */
blk_rq_set_block_pc(struct request * rq)1248 void blk_rq_set_block_pc(struct request *rq)
1249 {
1250 	rq->cmd_type = REQ_TYPE_BLOCK_PC;
1251 	rq->__data_len = 0;
1252 	rq->__sector = (sector_t) -1;
1253 	rq->bio = rq->biotail = NULL;
1254 	memset(rq->__cmd, 0, sizeof(rq->__cmd));
1255 }
1256 EXPORT_SYMBOL(blk_rq_set_block_pc);
1257 
1258 /**
1259  * blk_requeue_request - put a request back on queue
1260  * @q:		request queue where request should be inserted
1261  * @rq:		request to be inserted
1262  *
1263  * Description:
1264  *    Drivers often keep queueing requests until the hardware cannot accept
1265  *    more, when that condition happens we need to put the request back
1266  *    on the queue. Must be called with queue lock held.
1267  */
blk_requeue_request(struct request_queue * q,struct request * rq)1268 void blk_requeue_request(struct request_queue *q, struct request *rq)
1269 {
1270 	blk_delete_timer(rq);
1271 	blk_clear_rq_complete(rq);
1272 	trace_block_rq_requeue(q, rq);
1273 
1274 	if (blk_rq_tagged(rq))
1275 		blk_queue_end_tag(q, rq);
1276 
1277 	BUG_ON(blk_queued_rq(rq));
1278 
1279 	elv_requeue_request(q, rq);
1280 }
1281 EXPORT_SYMBOL(blk_requeue_request);
1282 
add_acct_request(struct request_queue * q,struct request * rq,int where)1283 static void add_acct_request(struct request_queue *q, struct request *rq,
1284 			     int where)
1285 {
1286 	blk_account_io_start(rq, true);
1287 	__elv_add_request(q, rq, where);
1288 }
1289 
part_round_stats_single(int cpu,struct hd_struct * part,unsigned long now)1290 static void part_round_stats_single(int cpu, struct hd_struct *part,
1291 				    unsigned long now)
1292 {
1293 	int inflight;
1294 
1295 	if (now == part->stamp)
1296 		return;
1297 
1298 	inflight = part_in_flight(part);
1299 	if (inflight) {
1300 		__part_stat_add(cpu, part, time_in_queue,
1301 				inflight * (now - part->stamp));
1302 		__part_stat_add(cpu, part, io_ticks, (now - part->stamp));
1303 	}
1304 	part->stamp = now;
1305 }
1306 
1307 /**
1308  * part_round_stats() - Round off the performance stats on a struct disk_stats.
1309  * @cpu: cpu number for stats access
1310  * @part: target partition
1311  *
1312  * The average IO queue length and utilisation statistics are maintained
1313  * by observing the current state of the queue length and the amount of
1314  * time it has been in this state for.
1315  *
1316  * Normally, that accounting is done on IO completion, but that can result
1317  * in more than a second's worth of IO being accounted for within any one
1318  * second, leading to >100% utilisation.  To deal with that, we call this
1319  * function to do a round-off before returning the results when reading
1320  * /proc/diskstats.  This accounts immediately for all queue usage up to
1321  * the current jiffies and restarts the counters again.
1322  */
part_round_stats(int cpu,struct hd_struct * part)1323 void part_round_stats(int cpu, struct hd_struct *part)
1324 {
1325 	unsigned long now = jiffies;
1326 
1327 	if (part->partno)
1328 		part_round_stats_single(cpu, &part_to_disk(part)->part0, now);
1329 	part_round_stats_single(cpu, part, now);
1330 }
1331 EXPORT_SYMBOL_GPL(part_round_stats);
1332 
1333 #ifdef CONFIG_PM_RUNTIME
blk_pm_put_request(struct request * rq)1334 static void blk_pm_put_request(struct request *rq)
1335 {
1336 	if (rq->q->dev && !(rq->cmd_flags & REQ_PM) && !--rq->q->nr_pending)
1337 		pm_runtime_mark_last_busy(rq->q->dev);
1338 }
1339 #else
blk_pm_put_request(struct request * rq)1340 static inline void blk_pm_put_request(struct request *rq) {}
1341 #endif
1342 
1343 /*
1344  * queue lock must be held
1345  */
__blk_put_request(struct request_queue * q,struct request * req)1346 void __blk_put_request(struct request_queue *q, struct request *req)
1347 {
1348 	if (unlikely(!q))
1349 		return;
1350 
1351 	if (q->mq_ops) {
1352 		blk_mq_free_request(req);
1353 		return;
1354 	}
1355 
1356 	blk_pm_put_request(req);
1357 
1358 	elv_completed_request(q, req);
1359 
1360 	/* this is a bio leak */
1361 	WARN_ON(req->bio != NULL);
1362 
1363 	/*
1364 	 * Request may not have originated from ll_rw_blk. if not,
1365 	 * it didn't come out of our reserved rq pools
1366 	 */
1367 	if (req->cmd_flags & REQ_ALLOCED) {
1368 		unsigned int flags = req->cmd_flags;
1369 		struct request_list *rl = blk_rq_rl(req);
1370 
1371 		BUG_ON(!list_empty(&req->queuelist));
1372 		BUG_ON(ELV_ON_HASH(req));
1373 
1374 		blk_free_request(rl, req);
1375 		freed_request(rl, flags);
1376 		blk_put_rl(rl);
1377 	}
1378 }
1379 EXPORT_SYMBOL_GPL(__blk_put_request);
1380 
blk_put_request(struct request * req)1381 void blk_put_request(struct request *req)
1382 {
1383 	struct request_queue *q = req->q;
1384 
1385 	if (q->mq_ops)
1386 		blk_mq_free_request(req);
1387 	else {
1388 		unsigned long flags;
1389 
1390 		spin_lock_irqsave(q->queue_lock, flags);
1391 		__blk_put_request(q, req);
1392 		spin_unlock_irqrestore(q->queue_lock, flags);
1393 	}
1394 }
1395 EXPORT_SYMBOL(blk_put_request);
1396 
1397 /**
1398  * blk_add_request_payload - add a payload to a request
1399  * @rq: request to update
1400  * @page: page backing the payload
1401  * @len: length of the payload.
1402  *
1403  * This allows to later add a payload to an already submitted request by
1404  * a block driver.  The driver needs to take care of freeing the payload
1405  * itself.
1406  *
1407  * Note that this is a quite horrible hack and nothing but handling of
1408  * discard requests should ever use it.
1409  */
blk_add_request_payload(struct request * rq,struct page * page,unsigned int len)1410 void blk_add_request_payload(struct request *rq, struct page *page,
1411 		unsigned int len)
1412 {
1413 	struct bio *bio = rq->bio;
1414 
1415 	bio->bi_io_vec->bv_page = page;
1416 	bio->bi_io_vec->bv_offset = 0;
1417 	bio->bi_io_vec->bv_len = len;
1418 
1419 	bio->bi_iter.bi_size = len;
1420 	bio->bi_vcnt = 1;
1421 	bio->bi_phys_segments = 1;
1422 
1423 	rq->__data_len = rq->resid_len = len;
1424 	rq->nr_phys_segments = 1;
1425 }
1426 EXPORT_SYMBOL_GPL(blk_add_request_payload);
1427 
bio_attempt_back_merge(struct request_queue * q,struct request * req,struct bio * bio)1428 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
1429 			    struct bio *bio)
1430 {
1431 	const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
1432 
1433 	if (!ll_back_merge_fn(q, req, bio))
1434 		return false;
1435 
1436 	trace_block_bio_backmerge(q, req, bio);
1437 
1438 	if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1439 		blk_rq_set_mixed_merge(req);
1440 
1441 	req->biotail->bi_next = bio;
1442 	req->biotail = bio;
1443 	req->__data_len += bio->bi_iter.bi_size;
1444 	req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1445 
1446 	blk_account_io_start(req, false);
1447 	return true;
1448 }
1449 
bio_attempt_front_merge(struct request_queue * q,struct request * req,struct bio * bio)1450 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
1451 			     struct bio *bio)
1452 {
1453 	const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
1454 
1455 	if (!ll_front_merge_fn(q, req, bio))
1456 		return false;
1457 
1458 	trace_block_bio_frontmerge(q, req, bio);
1459 
1460 	if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1461 		blk_rq_set_mixed_merge(req);
1462 
1463 	bio->bi_next = req->bio;
1464 	req->bio = bio;
1465 
1466 	req->__sector = bio->bi_iter.bi_sector;
1467 	req->__data_len += bio->bi_iter.bi_size;
1468 	req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1469 
1470 	blk_account_io_start(req, false);
1471 	return true;
1472 }
1473 
1474 /**
1475  * blk_attempt_plug_merge - try to merge with %current's plugged list
1476  * @q: request_queue new bio is being queued at
1477  * @bio: new bio being queued
1478  * @request_count: out parameter for number of traversed plugged requests
1479  *
1480  * Determine whether @bio being queued on @q can be merged with a request
1481  * on %current's plugged list.  Returns %true if merge was successful,
1482  * otherwise %false.
1483  *
1484  * Plugging coalesces IOs from the same issuer for the same purpose without
1485  * going through @q->queue_lock.  As such it's more of an issuing mechanism
1486  * than scheduling, and the request, while may have elvpriv data, is not
1487  * added on the elevator at this point.  In addition, we don't have
1488  * reliable access to the elevator outside queue lock.  Only check basic
1489  * merging parameters without querying the elevator.
1490  *
1491  * Caller must ensure !blk_queue_nomerges(q) beforehand.
1492  */
blk_attempt_plug_merge(struct request_queue * q,struct bio * bio,unsigned int * request_count)1493 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
1494 			    unsigned int *request_count)
1495 {
1496 	struct blk_plug *plug;
1497 	struct request *rq;
1498 	bool ret = false;
1499 	struct list_head *plug_list;
1500 
1501 	plug = current->plug;
1502 	if (!plug)
1503 		goto out;
1504 	*request_count = 0;
1505 
1506 	if (q->mq_ops)
1507 		plug_list = &plug->mq_list;
1508 	else
1509 		plug_list = &plug->list;
1510 
1511 	list_for_each_entry_reverse(rq, plug_list, queuelist) {
1512 		int el_ret;
1513 
1514 		if (rq->q == q)
1515 			(*request_count)++;
1516 
1517 		if (rq->q != q || !blk_rq_merge_ok(rq, bio))
1518 			continue;
1519 
1520 		el_ret = blk_try_merge(rq, bio);
1521 		if (el_ret == ELEVATOR_BACK_MERGE) {
1522 			ret = bio_attempt_back_merge(q, rq, bio);
1523 			if (ret)
1524 				break;
1525 		} else if (el_ret == ELEVATOR_FRONT_MERGE) {
1526 			ret = bio_attempt_front_merge(q, rq, bio);
1527 			if (ret)
1528 				break;
1529 		}
1530 	}
1531 out:
1532 	return ret;
1533 }
1534 
init_request_from_bio(struct request * req,struct bio * bio)1535 void init_request_from_bio(struct request *req, struct bio *bio)
1536 {
1537 	req->cmd_type = REQ_TYPE_FS;
1538 
1539 	req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK;
1540 	if (bio->bi_rw & REQ_RAHEAD)
1541 		req->cmd_flags |= REQ_FAILFAST_MASK;
1542 
1543 	req->errors = 0;
1544 	req->__sector = bio->bi_iter.bi_sector;
1545 	req->ioprio = bio_prio(bio);
1546 	blk_rq_bio_prep(req->q, req, bio);
1547 }
1548 
blk_queue_bio(struct request_queue * q,struct bio * bio)1549 void blk_queue_bio(struct request_queue *q, struct bio *bio)
1550 {
1551 	const bool sync = !!(bio->bi_rw & REQ_SYNC);
1552 	struct blk_plug *plug;
1553 	int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT;
1554 	struct request *req;
1555 	unsigned int request_count = 0;
1556 
1557 	/*
1558 	 * low level driver can indicate that it wants pages above a
1559 	 * certain limit bounced to low memory (ie for highmem, or even
1560 	 * ISA dma in theory)
1561 	 */
1562 	blk_queue_bounce(q, &bio);
1563 
1564 	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1565 		bio_endio(bio, -EIO);
1566 		return;
1567 	}
1568 
1569 	if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
1570 		spin_lock_irq(q->queue_lock);
1571 		where = ELEVATOR_INSERT_FLUSH;
1572 		goto get_rq;
1573 	}
1574 
1575 	/*
1576 	 * Check if we can merge with the plugged list before grabbing
1577 	 * any locks.
1578 	 */
1579 	if (!blk_queue_nomerges(q) &&
1580 	    blk_attempt_plug_merge(q, bio, &request_count))
1581 		return;
1582 
1583 	spin_lock_irq(q->queue_lock);
1584 
1585 	el_ret = elv_merge(q, &req, bio);
1586 	if (el_ret == ELEVATOR_BACK_MERGE) {
1587 		if (bio_attempt_back_merge(q, req, bio)) {
1588 			elv_bio_merged(q, req, bio);
1589 			if (!attempt_back_merge(q, req))
1590 				elv_merged_request(q, req, el_ret);
1591 			goto out_unlock;
1592 		}
1593 	} else if (el_ret == ELEVATOR_FRONT_MERGE) {
1594 		if (bio_attempt_front_merge(q, req, bio)) {
1595 			elv_bio_merged(q, req, bio);
1596 			if (!attempt_front_merge(q, req))
1597 				elv_merged_request(q, req, el_ret);
1598 			goto out_unlock;
1599 		}
1600 	}
1601 
1602 get_rq:
1603 	/*
1604 	 * This sync check and mask will be re-done in init_request_from_bio(),
1605 	 * but we need to set it earlier to expose the sync flag to the
1606 	 * rq allocator and io schedulers.
1607 	 */
1608 	rw_flags = bio_data_dir(bio);
1609 	if (sync)
1610 		rw_flags |= REQ_SYNC;
1611 
1612 	/*
1613 	 * Grab a free request. This is might sleep but can not fail.
1614 	 * Returns with the queue unlocked.
1615 	 */
1616 	req = get_request(q, rw_flags, bio, GFP_NOIO);
1617 	if (IS_ERR(req)) {
1618 		bio_endio(bio, PTR_ERR(req));	/* @q is dead */
1619 		goto out_unlock;
1620 	}
1621 
1622 	/*
1623 	 * After dropping the lock and possibly sleeping here, our request
1624 	 * may now be mergeable after it had proven unmergeable (above).
1625 	 * We don't worry about that case for efficiency. It won't happen
1626 	 * often, and the elevators are able to handle it.
1627 	 */
1628 	init_request_from_bio(req, bio);
1629 
1630 	if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags))
1631 		req->cpu = raw_smp_processor_id();
1632 
1633 	plug = current->plug;
1634 	if (plug) {
1635 		/*
1636 		 * If this is the first request added after a plug, fire
1637 		 * of a plug trace.
1638 		 */
1639 		if (!request_count)
1640 			trace_block_plug(q);
1641 		else {
1642 			if (request_count >= BLK_MAX_REQUEST_COUNT) {
1643 				blk_flush_plug_list(plug, false);
1644 				trace_block_plug(q);
1645 			}
1646 		}
1647 		list_add_tail(&req->queuelist, &plug->list);
1648 		blk_account_io_start(req, true);
1649 	} else {
1650 		spin_lock_irq(q->queue_lock);
1651 		add_acct_request(q, req, where);
1652 		__blk_run_queue(q);
1653 out_unlock:
1654 		spin_unlock_irq(q->queue_lock);
1655 	}
1656 }
1657 EXPORT_SYMBOL_GPL(blk_queue_bio);	/* for device mapper only */
1658 
1659 /*
1660  * If bio->bi_dev is a partition, remap the location
1661  */
blk_partition_remap(struct bio * bio)1662 static inline void blk_partition_remap(struct bio *bio)
1663 {
1664 	struct block_device *bdev = bio->bi_bdev;
1665 
1666 	if (bio_sectors(bio) && bdev != bdev->bd_contains) {
1667 		struct hd_struct *p = bdev->bd_part;
1668 
1669 		bio->bi_iter.bi_sector += p->start_sect;
1670 		bio->bi_bdev = bdev->bd_contains;
1671 
1672 		trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio,
1673 				      bdev->bd_dev,
1674 				      bio->bi_iter.bi_sector - p->start_sect);
1675 	}
1676 }
1677 
handle_bad_sector(struct bio * bio)1678 static void handle_bad_sector(struct bio *bio)
1679 {
1680 	char b[BDEVNAME_SIZE];
1681 
1682 	printk(KERN_INFO "attempt to access beyond end of device\n");
1683 	printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
1684 			bdevname(bio->bi_bdev, b),
1685 			bio->bi_rw,
1686 			(unsigned long long)bio_end_sector(bio),
1687 			(long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9));
1688 
1689 	set_bit(BIO_EOF, &bio->bi_flags);
1690 }
1691 
1692 #ifdef CONFIG_FAIL_MAKE_REQUEST
1693 
1694 static DECLARE_FAULT_ATTR(fail_make_request);
1695 
setup_fail_make_request(char * str)1696 static int __init setup_fail_make_request(char *str)
1697 {
1698 	return setup_fault_attr(&fail_make_request, str);
1699 }
1700 __setup("fail_make_request=", setup_fail_make_request);
1701 
should_fail_request(struct hd_struct * part,unsigned int bytes)1702 static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
1703 {
1704 	return part->make_it_fail && should_fail(&fail_make_request, bytes);
1705 }
1706 
fail_make_request_debugfs(void)1707 static int __init fail_make_request_debugfs(void)
1708 {
1709 	struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
1710 						NULL, &fail_make_request);
1711 
1712 	return PTR_ERR_OR_ZERO(dir);
1713 }
1714 
1715 late_initcall(fail_make_request_debugfs);
1716 
1717 #else /* CONFIG_FAIL_MAKE_REQUEST */
1718 
should_fail_request(struct hd_struct * part,unsigned int bytes)1719 static inline bool should_fail_request(struct hd_struct *part,
1720 					unsigned int bytes)
1721 {
1722 	return false;
1723 }
1724 
1725 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1726 
1727 /*
1728  * Check whether this bio extends beyond the end of the device.
1729  */
bio_check_eod(struct bio * bio,unsigned int nr_sectors)1730 static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
1731 {
1732 	sector_t maxsector;
1733 
1734 	if (!nr_sectors)
1735 		return 0;
1736 
1737 	/* Test device or partition size, when known. */
1738 	maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
1739 	if (maxsector) {
1740 		sector_t sector = bio->bi_iter.bi_sector;
1741 
1742 		if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
1743 			/*
1744 			 * This may well happen - the kernel calls bread()
1745 			 * without checking the size of the device, e.g., when
1746 			 * mounting a device.
1747 			 */
1748 			handle_bad_sector(bio);
1749 			return 1;
1750 		}
1751 	}
1752 
1753 	return 0;
1754 }
1755 
1756 static noinline_for_stack bool
generic_make_request_checks(struct bio * bio)1757 generic_make_request_checks(struct bio *bio)
1758 {
1759 	struct request_queue *q;
1760 	int nr_sectors = bio_sectors(bio);
1761 	int err = -EIO;
1762 	char b[BDEVNAME_SIZE];
1763 	struct hd_struct *part;
1764 
1765 	might_sleep();
1766 
1767 	if (bio_check_eod(bio, nr_sectors))
1768 		goto end_io;
1769 
1770 	q = bdev_get_queue(bio->bi_bdev);
1771 	if (unlikely(!q)) {
1772 		printk(KERN_ERR
1773 		       "generic_make_request: Trying to access "
1774 			"nonexistent block-device %s (%Lu)\n",
1775 			bdevname(bio->bi_bdev, b),
1776 			(long long) bio->bi_iter.bi_sector);
1777 		goto end_io;
1778 	}
1779 
1780 	if (likely(bio_is_rw(bio) &&
1781 		   nr_sectors > queue_max_hw_sectors(q))) {
1782 		printk(KERN_ERR "bio too big device %s (%u > %u)\n",
1783 		       bdevname(bio->bi_bdev, b),
1784 		       bio_sectors(bio),
1785 		       queue_max_hw_sectors(q));
1786 		goto end_io;
1787 	}
1788 
1789 	part = bio->bi_bdev->bd_part;
1790 	if (should_fail_request(part, bio->bi_iter.bi_size) ||
1791 	    should_fail_request(&part_to_disk(part)->part0,
1792 				bio->bi_iter.bi_size))
1793 		goto end_io;
1794 
1795 	/*
1796 	 * If this device has partitions, remap block n
1797 	 * of partition p to block n+start(p) of the disk.
1798 	 */
1799 	blk_partition_remap(bio);
1800 
1801 	if (bio_check_eod(bio, nr_sectors))
1802 		goto end_io;
1803 
1804 	/*
1805 	 * Filter flush bio's early so that make_request based
1806 	 * drivers without flush support don't have to worry
1807 	 * about them.
1808 	 */
1809 	if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) {
1810 		bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA);
1811 		if (!nr_sectors) {
1812 			err = 0;
1813 			goto end_io;
1814 		}
1815 	}
1816 
1817 	if ((bio->bi_rw & REQ_DISCARD) &&
1818 	    (!blk_queue_discard(q) ||
1819 	     ((bio->bi_rw & REQ_SECURE) && !blk_queue_secdiscard(q)))) {
1820 		err = -EOPNOTSUPP;
1821 		goto end_io;
1822 	}
1823 
1824 	if (bio->bi_rw & REQ_WRITE_SAME && !bdev_write_same(bio->bi_bdev)) {
1825 		err = -EOPNOTSUPP;
1826 		goto end_io;
1827 	}
1828 
1829 	/*
1830 	 * Various block parts want %current->io_context and lazy ioc
1831 	 * allocation ends up trading a lot of pain for a small amount of
1832 	 * memory.  Just allocate it upfront.  This may fail and block
1833 	 * layer knows how to live with it.
1834 	 */
1835 	create_io_context(GFP_ATOMIC, q->node);
1836 
1837 	if (blk_throtl_bio(q, bio))
1838 		return false;	/* throttled, will be resubmitted later */
1839 
1840 	trace_block_bio_queue(q, bio);
1841 	return true;
1842 
1843 end_io:
1844 	bio_endio(bio, err);
1845 	return false;
1846 }
1847 
1848 /**
1849  * generic_make_request - hand a buffer to its device driver for I/O
1850  * @bio:  The bio describing the location in memory and on the device.
1851  *
1852  * generic_make_request() is used to make I/O requests of block
1853  * devices. It is passed a &struct bio, which describes the I/O that needs
1854  * to be done.
1855  *
1856  * generic_make_request() does not return any status.  The
1857  * success/failure status of the request, along with notification of
1858  * completion, is delivered asynchronously through the bio->bi_end_io
1859  * function described (one day) else where.
1860  *
1861  * The caller of generic_make_request must make sure that bi_io_vec
1862  * are set to describe the memory buffer, and that bi_dev and bi_sector are
1863  * set to describe the device address, and the
1864  * bi_end_io and optionally bi_private are set to describe how
1865  * completion notification should be signaled.
1866  *
1867  * generic_make_request and the drivers it calls may use bi_next if this
1868  * bio happens to be merged with someone else, and may resubmit the bio to
1869  * a lower device by calling into generic_make_request recursively, which
1870  * means the bio should NOT be touched after the call to ->make_request_fn.
1871  */
generic_make_request(struct bio * bio)1872 void generic_make_request(struct bio *bio)
1873 {
1874 	struct bio_list bio_list_on_stack;
1875 
1876 	if (!generic_make_request_checks(bio))
1877 		return;
1878 
1879 	/*
1880 	 * We only want one ->make_request_fn to be active at a time, else
1881 	 * stack usage with stacked devices could be a problem.  So use
1882 	 * current->bio_list to keep a list of requests submited by a
1883 	 * make_request_fn function.  current->bio_list is also used as a
1884 	 * flag to say if generic_make_request is currently active in this
1885 	 * task or not.  If it is NULL, then no make_request is active.  If
1886 	 * it is non-NULL, then a make_request is active, and new requests
1887 	 * should be added at the tail
1888 	 */
1889 	if (current->bio_list) {
1890 		bio_list_add(current->bio_list, bio);
1891 		return;
1892 	}
1893 
1894 	/* following loop may be a bit non-obvious, and so deserves some
1895 	 * explanation.
1896 	 * Before entering the loop, bio->bi_next is NULL (as all callers
1897 	 * ensure that) so we have a list with a single bio.
1898 	 * We pretend that we have just taken it off a longer list, so
1899 	 * we assign bio_list to a pointer to the bio_list_on_stack,
1900 	 * thus initialising the bio_list of new bios to be
1901 	 * added.  ->make_request() may indeed add some more bios
1902 	 * through a recursive call to generic_make_request.  If it
1903 	 * did, we find a non-NULL value in bio_list and re-enter the loop
1904 	 * from the top.  In this case we really did just take the bio
1905 	 * of the top of the list (no pretending) and so remove it from
1906 	 * bio_list, and call into ->make_request() again.
1907 	 */
1908 	BUG_ON(bio->bi_next);
1909 	bio_list_init(&bio_list_on_stack);
1910 	current->bio_list = &bio_list_on_stack;
1911 	do {
1912 		struct request_queue *q = bdev_get_queue(bio->bi_bdev);
1913 
1914 		q->make_request_fn(q, bio);
1915 
1916 		bio = bio_list_pop(current->bio_list);
1917 	} while (bio);
1918 	current->bio_list = NULL; /* deactivate */
1919 }
1920 EXPORT_SYMBOL(generic_make_request);
1921 
1922 /**
1923  * submit_bio - submit a bio to the block device layer for I/O
1924  * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
1925  * @bio: The &struct bio which describes the I/O
1926  *
1927  * submit_bio() is very similar in purpose to generic_make_request(), and
1928  * uses that function to do most of the work. Both are fairly rough
1929  * interfaces; @bio must be presetup and ready for I/O.
1930  *
1931  */
submit_bio(int rw,struct bio * bio)1932 void submit_bio(int rw, struct bio *bio)
1933 {
1934 	bio->bi_rw |= rw;
1935 
1936 	/*
1937 	 * If it's a regular read/write or a barrier with data attached,
1938 	 * go through the normal accounting stuff before submission.
1939 	 */
1940 	if (bio_has_data(bio)) {
1941 		unsigned int count;
1942 
1943 		if (unlikely(rw & REQ_WRITE_SAME))
1944 			count = bdev_logical_block_size(bio->bi_bdev) >> 9;
1945 		else
1946 			count = bio_sectors(bio);
1947 
1948 		if (rw & WRITE) {
1949 			count_vm_events(PGPGOUT, count);
1950 		} else {
1951 			task_io_account_read(bio->bi_iter.bi_size);
1952 			count_vm_events(PGPGIN, count);
1953 		}
1954 
1955 		if (unlikely(block_dump)) {
1956 			char b[BDEVNAME_SIZE];
1957 			printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
1958 			current->comm, task_pid_nr(current),
1959 				(rw & WRITE) ? "WRITE" : "READ",
1960 				(unsigned long long)bio->bi_iter.bi_sector,
1961 				bdevname(bio->bi_bdev, b),
1962 				count);
1963 		}
1964 	}
1965 
1966 	generic_make_request(bio);
1967 }
1968 EXPORT_SYMBOL(submit_bio);
1969 
1970 /**
1971  * blk_rq_check_limits - Helper function to check a request for the queue limit
1972  * @q:  the queue
1973  * @rq: the request being checked
1974  *
1975  * Description:
1976  *    @rq may have been made based on weaker limitations of upper-level queues
1977  *    in request stacking drivers, and it may violate the limitation of @q.
1978  *    Since the block layer and the underlying device driver trust @rq
1979  *    after it is inserted to @q, it should be checked against @q before
1980  *    the insertion using this generic function.
1981  *
1982  *    This function should also be useful for request stacking drivers
1983  *    in some cases below, so export this function.
1984  *    Request stacking drivers like request-based dm may change the queue
1985  *    limits while requests are in the queue (e.g. dm's table swapping).
1986  *    Such request stacking drivers should check those requests against
1987  *    the new queue limits again when they dispatch those requests,
1988  *    although such checkings are also done against the old queue limits
1989  *    when submitting requests.
1990  */
blk_rq_check_limits(struct request_queue * q,struct request * rq)1991 int blk_rq_check_limits(struct request_queue *q, struct request *rq)
1992 {
1993 	if (!rq_mergeable(rq))
1994 		return 0;
1995 
1996 	if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, rq->cmd_flags)) {
1997 		printk(KERN_ERR "%s: over max size limit.\n", __func__);
1998 		return -EIO;
1999 	}
2000 
2001 	/*
2002 	 * queue's settings related to segment counting like q->bounce_pfn
2003 	 * may differ from that of other stacking queues.
2004 	 * Recalculate it to check the request correctly on this queue's
2005 	 * limitation.
2006 	 */
2007 	blk_recalc_rq_segments(rq);
2008 	if (rq->nr_phys_segments > queue_max_segments(q)) {
2009 		printk(KERN_ERR "%s: over max segments limit.\n", __func__);
2010 		return -EIO;
2011 	}
2012 
2013 	return 0;
2014 }
2015 EXPORT_SYMBOL_GPL(blk_rq_check_limits);
2016 
2017 /**
2018  * blk_insert_cloned_request - Helper for stacking drivers to submit a request
2019  * @q:  the queue to submit the request
2020  * @rq: the request being queued
2021  */
blk_insert_cloned_request(struct request_queue * q,struct request * rq)2022 int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
2023 {
2024 	unsigned long flags;
2025 	int where = ELEVATOR_INSERT_BACK;
2026 
2027 	if (blk_rq_check_limits(q, rq))
2028 		return -EIO;
2029 
2030 	if (rq->rq_disk &&
2031 	    should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
2032 		return -EIO;
2033 
2034 	spin_lock_irqsave(q->queue_lock, flags);
2035 	if (unlikely(blk_queue_dying(q))) {
2036 		spin_unlock_irqrestore(q->queue_lock, flags);
2037 		return -ENODEV;
2038 	}
2039 
2040 	/*
2041 	 * Submitting request must be dequeued before calling this function
2042 	 * because it will be linked to another request_queue
2043 	 */
2044 	BUG_ON(blk_queued_rq(rq));
2045 
2046 	if (rq->cmd_flags & (REQ_FLUSH|REQ_FUA))
2047 		where = ELEVATOR_INSERT_FLUSH;
2048 
2049 	add_acct_request(q, rq, where);
2050 	if (where == ELEVATOR_INSERT_FLUSH)
2051 		__blk_run_queue(q);
2052 	spin_unlock_irqrestore(q->queue_lock, flags);
2053 
2054 	return 0;
2055 }
2056 EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
2057 
2058 /**
2059  * blk_rq_err_bytes - determine number of bytes till the next failure boundary
2060  * @rq: request to examine
2061  *
2062  * Description:
2063  *     A request could be merge of IOs which require different failure
2064  *     handling.  This function determines the number of bytes which
2065  *     can be failed from the beginning of the request without
2066  *     crossing into area which need to be retried further.
2067  *
2068  * Return:
2069  *     The number of bytes to fail.
2070  *
2071  * Context:
2072  *     queue_lock must be held.
2073  */
blk_rq_err_bytes(const struct request * rq)2074 unsigned int blk_rq_err_bytes(const struct request *rq)
2075 {
2076 	unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
2077 	unsigned int bytes = 0;
2078 	struct bio *bio;
2079 
2080 	if (!(rq->cmd_flags & REQ_MIXED_MERGE))
2081 		return blk_rq_bytes(rq);
2082 
2083 	/*
2084 	 * Currently the only 'mixing' which can happen is between
2085 	 * different fastfail types.  We can safely fail portions
2086 	 * which have all the failfast bits that the first one has -
2087 	 * the ones which are at least as eager to fail as the first
2088 	 * one.
2089 	 */
2090 	for (bio = rq->bio; bio; bio = bio->bi_next) {
2091 		if ((bio->bi_rw & ff) != ff)
2092 			break;
2093 		bytes += bio->bi_iter.bi_size;
2094 	}
2095 
2096 	/* this could lead to infinite loop */
2097 	BUG_ON(blk_rq_bytes(rq) && !bytes);
2098 	return bytes;
2099 }
2100 EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
2101 
blk_account_io_completion(struct request * req,unsigned int bytes)2102 void blk_account_io_completion(struct request *req, unsigned int bytes)
2103 {
2104 	if (blk_do_io_stat(req)) {
2105 		const int rw = rq_data_dir(req);
2106 		struct hd_struct *part;
2107 		int cpu;
2108 
2109 		cpu = part_stat_lock();
2110 		part = req->part;
2111 		part_stat_add(cpu, part, sectors[rw], bytes >> 9);
2112 		part_stat_unlock();
2113 	}
2114 }
2115 
blk_account_io_done(struct request * req)2116 void blk_account_io_done(struct request *req)
2117 {
2118 	/*
2119 	 * Account IO completion.  flush_rq isn't accounted as a
2120 	 * normal IO on queueing nor completion.  Accounting the
2121 	 * containing request is enough.
2122 	 */
2123 	if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) {
2124 		unsigned long duration = jiffies - req->start_time;
2125 		const int rw = rq_data_dir(req);
2126 		struct hd_struct *part;
2127 		int cpu;
2128 
2129 		cpu = part_stat_lock();
2130 		part = req->part;
2131 
2132 		part_stat_inc(cpu, part, ios[rw]);
2133 		part_stat_add(cpu, part, ticks[rw], duration);
2134 		part_round_stats(cpu, part);
2135 		part_dec_in_flight(part, rw);
2136 
2137 		hd_struct_put(part);
2138 		part_stat_unlock();
2139 	}
2140 }
2141 
2142 #ifdef CONFIG_PM_RUNTIME
2143 /*
2144  * Don't process normal requests when queue is suspended
2145  * or in the process of suspending/resuming
2146  */
blk_pm_peek_request(struct request_queue * q,struct request * rq)2147 static struct request *blk_pm_peek_request(struct request_queue *q,
2148 					   struct request *rq)
2149 {
2150 	if (q->dev && (q->rpm_status == RPM_SUSPENDED ||
2151 	    (q->rpm_status != RPM_ACTIVE && !(rq->cmd_flags & REQ_PM))))
2152 		return NULL;
2153 	else
2154 		return rq;
2155 }
2156 #else
blk_pm_peek_request(struct request_queue * q,struct request * rq)2157 static inline struct request *blk_pm_peek_request(struct request_queue *q,
2158 						  struct request *rq)
2159 {
2160 	return rq;
2161 }
2162 #endif
2163 
blk_account_io_start(struct request * rq,bool new_io)2164 void blk_account_io_start(struct request *rq, bool new_io)
2165 {
2166 	struct hd_struct *part;
2167 	int rw = rq_data_dir(rq);
2168 	int cpu;
2169 
2170 	if (!blk_do_io_stat(rq))
2171 		return;
2172 
2173 	cpu = part_stat_lock();
2174 
2175 	if (!new_io) {
2176 		part = rq->part;
2177 		part_stat_inc(cpu, part, merges[rw]);
2178 	} else {
2179 		part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
2180 		if (!hd_struct_try_get(part)) {
2181 			/*
2182 			 * The partition is already being removed,
2183 			 * the request will be accounted on the disk only
2184 			 *
2185 			 * We take a reference on disk->part0 although that
2186 			 * partition will never be deleted, so we can treat
2187 			 * it as any other partition.
2188 			 */
2189 			part = &rq->rq_disk->part0;
2190 			hd_struct_get(part);
2191 		}
2192 		part_round_stats(cpu, part);
2193 		part_inc_in_flight(part, rw);
2194 		rq->part = part;
2195 	}
2196 
2197 	part_stat_unlock();
2198 }
2199 
2200 /**
2201  * blk_peek_request - peek at the top of a request queue
2202  * @q: request queue to peek at
2203  *
2204  * Description:
2205  *     Return the request at the top of @q.  The returned request
2206  *     should be started using blk_start_request() before LLD starts
2207  *     processing it.
2208  *
2209  * Return:
2210  *     Pointer to the request at the top of @q if available.  Null
2211  *     otherwise.
2212  *
2213  * Context:
2214  *     queue_lock must be held.
2215  */
blk_peek_request(struct request_queue * q)2216 struct request *blk_peek_request(struct request_queue *q)
2217 {
2218 	struct request *rq;
2219 	int ret;
2220 
2221 	while ((rq = __elv_next_request(q)) != NULL) {
2222 
2223 		rq = blk_pm_peek_request(q, rq);
2224 		if (!rq)
2225 			break;
2226 
2227 		if (!(rq->cmd_flags & REQ_STARTED)) {
2228 			/*
2229 			 * This is the first time the device driver
2230 			 * sees this request (possibly after
2231 			 * requeueing).  Notify IO scheduler.
2232 			 */
2233 			if (rq->cmd_flags & REQ_SORTED)
2234 				elv_activate_rq(q, rq);
2235 
2236 			/*
2237 			 * just mark as started even if we don't start
2238 			 * it, a request that has been delayed should
2239 			 * not be passed by new incoming requests
2240 			 */
2241 			rq->cmd_flags |= REQ_STARTED;
2242 			trace_block_rq_issue(q, rq);
2243 		}
2244 
2245 		if (!q->boundary_rq || q->boundary_rq == rq) {
2246 			q->end_sector = rq_end_sector(rq);
2247 			q->boundary_rq = NULL;
2248 		}
2249 
2250 		if (rq->cmd_flags & REQ_DONTPREP)
2251 			break;
2252 
2253 		if (q->dma_drain_size && blk_rq_bytes(rq)) {
2254 			/*
2255 			 * make sure space for the drain appears we
2256 			 * know we can do this because max_hw_segments
2257 			 * has been adjusted to be one fewer than the
2258 			 * device can handle
2259 			 */
2260 			rq->nr_phys_segments++;
2261 		}
2262 
2263 		if (!q->prep_rq_fn)
2264 			break;
2265 
2266 		ret = q->prep_rq_fn(q, rq);
2267 		if (ret == BLKPREP_OK) {
2268 			break;
2269 		} else if (ret == BLKPREP_DEFER) {
2270 			/*
2271 			 * the request may have been (partially) prepped.
2272 			 * we need to keep this request in the front to
2273 			 * avoid resource deadlock.  REQ_STARTED will
2274 			 * prevent other fs requests from passing this one.
2275 			 */
2276 			if (q->dma_drain_size && blk_rq_bytes(rq) &&
2277 			    !(rq->cmd_flags & REQ_DONTPREP)) {
2278 				/*
2279 				 * remove the space for the drain we added
2280 				 * so that we don't add it again
2281 				 */
2282 				--rq->nr_phys_segments;
2283 			}
2284 
2285 			rq = NULL;
2286 			break;
2287 		} else if (ret == BLKPREP_KILL) {
2288 			rq->cmd_flags |= REQ_QUIET;
2289 			/*
2290 			 * Mark this request as started so we don't trigger
2291 			 * any debug logic in the end I/O path.
2292 			 */
2293 			blk_start_request(rq);
2294 			__blk_end_request_all(rq, -EIO);
2295 		} else {
2296 			printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
2297 			break;
2298 		}
2299 	}
2300 
2301 	return rq;
2302 }
2303 EXPORT_SYMBOL(blk_peek_request);
2304 
blk_dequeue_request(struct request * rq)2305 void blk_dequeue_request(struct request *rq)
2306 {
2307 	struct request_queue *q = rq->q;
2308 
2309 	BUG_ON(list_empty(&rq->queuelist));
2310 	BUG_ON(ELV_ON_HASH(rq));
2311 
2312 	list_del_init(&rq->queuelist);
2313 
2314 	/*
2315 	 * the time frame between a request being removed from the lists
2316 	 * and to it is freed is accounted as io that is in progress at
2317 	 * the driver side.
2318 	 */
2319 	if (blk_account_rq(rq)) {
2320 		q->in_flight[rq_is_sync(rq)]++;
2321 		set_io_start_time_ns(rq);
2322 	}
2323 }
2324 
2325 /**
2326  * blk_start_request - start request processing on the driver
2327  * @req: request to dequeue
2328  *
2329  * Description:
2330  *     Dequeue @req and start timeout timer on it.  This hands off the
2331  *     request to the driver.
2332  *
2333  *     Block internal functions which don't want to start timer should
2334  *     call blk_dequeue_request().
2335  *
2336  * Context:
2337  *     queue_lock must be held.
2338  */
blk_start_request(struct request * req)2339 void blk_start_request(struct request *req)
2340 {
2341 	blk_dequeue_request(req);
2342 
2343 	/*
2344 	 * We are now handing the request to the hardware, initialize
2345 	 * resid_len to full count and add the timeout handler.
2346 	 */
2347 	req->resid_len = blk_rq_bytes(req);
2348 	if (unlikely(blk_bidi_rq(req)))
2349 		req->next_rq->resid_len = blk_rq_bytes(req->next_rq);
2350 
2351 	BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
2352 	blk_add_timer(req);
2353 }
2354 EXPORT_SYMBOL(blk_start_request);
2355 
2356 /**
2357  * blk_fetch_request - fetch a request from a request queue
2358  * @q: request queue to fetch a request from
2359  *
2360  * Description:
2361  *     Return the request at the top of @q.  The request is started on
2362  *     return and LLD can start processing it immediately.
2363  *
2364  * Return:
2365  *     Pointer to the request at the top of @q if available.  Null
2366  *     otherwise.
2367  *
2368  * Context:
2369  *     queue_lock must be held.
2370  */
blk_fetch_request(struct request_queue * q)2371 struct request *blk_fetch_request(struct request_queue *q)
2372 {
2373 	struct request *rq;
2374 
2375 	rq = blk_peek_request(q);
2376 	if (rq)
2377 		blk_start_request(rq);
2378 	return rq;
2379 }
2380 EXPORT_SYMBOL(blk_fetch_request);
2381 
2382 /**
2383  * blk_update_request - Special helper function for request stacking drivers
2384  * @req:      the request being processed
2385  * @error:    %0 for success, < %0 for error
2386  * @nr_bytes: number of bytes to complete @req
2387  *
2388  * Description:
2389  *     Ends I/O on a number of bytes attached to @req, but doesn't complete
2390  *     the request structure even if @req doesn't have leftover.
2391  *     If @req has leftover, sets it up for the next range of segments.
2392  *
2393  *     This special helper function is only for request stacking drivers
2394  *     (e.g. request-based dm) so that they can handle partial completion.
2395  *     Actual device drivers should use blk_end_request instead.
2396  *
2397  *     Passing the result of blk_rq_bytes() as @nr_bytes guarantees
2398  *     %false return from this function.
2399  *
2400  * Return:
2401  *     %false - this request doesn't have any more data
2402  *     %true  - this request has more data
2403  **/
blk_update_request(struct request * req,int error,unsigned int nr_bytes)2404 bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
2405 {
2406 	int total_bytes;
2407 
2408 	trace_block_rq_complete(req->q, req, nr_bytes);
2409 
2410 	if (!req->bio)
2411 		return false;
2412 
2413 	/*
2414 	 * For fs requests, rq is just carrier of independent bio's
2415 	 * and each partial completion should be handled separately.
2416 	 * Reset per-request error on each partial completion.
2417 	 *
2418 	 * TODO: tj: This is too subtle.  It would be better to let
2419 	 * low level drivers do what they see fit.
2420 	 */
2421 	if (req->cmd_type == REQ_TYPE_FS)
2422 		req->errors = 0;
2423 
2424 	if (error && req->cmd_type == REQ_TYPE_FS &&
2425 	    !(req->cmd_flags & REQ_QUIET)) {
2426 		char *error_type;
2427 
2428 		switch (error) {
2429 		case -ENOLINK:
2430 			error_type = "recoverable transport";
2431 			break;
2432 		case -EREMOTEIO:
2433 			error_type = "critical target";
2434 			break;
2435 		case -EBADE:
2436 			error_type = "critical nexus";
2437 			break;
2438 		case -ETIMEDOUT:
2439 			error_type = "timeout";
2440 			break;
2441 		case -ENOSPC:
2442 			error_type = "critical space allocation";
2443 			break;
2444 		case -ENODATA:
2445 			error_type = "critical medium";
2446 			break;
2447 		case -EIO:
2448 		default:
2449 			error_type = "I/O";
2450 			break;
2451 		}
2452 		printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n",
2453 				   __func__, error_type, req->rq_disk ?
2454 				   req->rq_disk->disk_name : "?",
2455 				   (unsigned long long)blk_rq_pos(req));
2456 
2457 	}
2458 
2459 	blk_account_io_completion(req, nr_bytes);
2460 
2461 	total_bytes = 0;
2462 	while (req->bio) {
2463 		struct bio *bio = req->bio;
2464 		unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);
2465 
2466 		if (bio_bytes == bio->bi_iter.bi_size)
2467 			req->bio = bio->bi_next;
2468 
2469 		req_bio_endio(req, bio, bio_bytes, error);
2470 
2471 		total_bytes += bio_bytes;
2472 		nr_bytes -= bio_bytes;
2473 
2474 		if (!nr_bytes)
2475 			break;
2476 	}
2477 
2478 	/*
2479 	 * completely done
2480 	 */
2481 	if (!req->bio) {
2482 		/*
2483 		 * Reset counters so that the request stacking driver
2484 		 * can find how many bytes remain in the request
2485 		 * later.
2486 		 */
2487 		req->__data_len = 0;
2488 		return false;
2489 	}
2490 
2491 	req->__data_len -= total_bytes;
2492 
2493 	/* update sector only for requests with clear definition of sector */
2494 	if (req->cmd_type == REQ_TYPE_FS)
2495 		req->__sector += total_bytes >> 9;
2496 
2497 	/* mixed attributes always follow the first bio */
2498 	if (req->cmd_flags & REQ_MIXED_MERGE) {
2499 		req->cmd_flags &= ~REQ_FAILFAST_MASK;
2500 		req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK;
2501 	}
2502 
2503 	/*
2504 	 * If total number of sectors is less than the first segment
2505 	 * size, something has gone terribly wrong.
2506 	 */
2507 	if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
2508 		blk_dump_rq_flags(req, "request botched");
2509 		req->__data_len = blk_rq_cur_bytes(req);
2510 	}
2511 
2512 	/* recalculate the number of segments */
2513 	blk_recalc_rq_segments(req);
2514 
2515 	return true;
2516 }
2517 EXPORT_SYMBOL_GPL(blk_update_request);
2518 
blk_update_bidi_request(struct request * rq,int error,unsigned int nr_bytes,unsigned int bidi_bytes)2519 static bool blk_update_bidi_request(struct request *rq, int error,
2520 				    unsigned int nr_bytes,
2521 				    unsigned int bidi_bytes)
2522 {
2523 	if (blk_update_request(rq, error, nr_bytes))
2524 		return true;
2525 
2526 	/* Bidi request must be completed as a whole */
2527 	if (unlikely(blk_bidi_rq(rq)) &&
2528 	    blk_update_request(rq->next_rq, error, bidi_bytes))
2529 		return true;
2530 
2531 	if (blk_queue_add_random(rq->q))
2532 		add_disk_randomness(rq->rq_disk);
2533 
2534 	return false;
2535 }
2536 
2537 /**
2538  * blk_unprep_request - unprepare a request
2539  * @req:	the request
2540  *
2541  * This function makes a request ready for complete resubmission (or
2542  * completion).  It happens only after all error handling is complete,
2543  * so represents the appropriate moment to deallocate any resources
2544  * that were allocated to the request in the prep_rq_fn.  The queue
2545  * lock is held when calling this.
2546  */
blk_unprep_request(struct request * req)2547 void blk_unprep_request(struct request *req)
2548 {
2549 	struct request_queue *q = req->q;
2550 
2551 	req->cmd_flags &= ~REQ_DONTPREP;
2552 	if (q->unprep_rq_fn)
2553 		q->unprep_rq_fn(q, req);
2554 }
2555 EXPORT_SYMBOL_GPL(blk_unprep_request);
2556 
2557 /*
2558  * queue lock must be held
2559  */
blk_finish_request(struct request * req,int error)2560 void blk_finish_request(struct request *req, int error)
2561 {
2562 	if (blk_rq_tagged(req))
2563 		blk_queue_end_tag(req->q, req);
2564 
2565 	BUG_ON(blk_queued_rq(req));
2566 
2567 	if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS)
2568 		laptop_io_completion(&req->q->backing_dev_info);
2569 
2570 	blk_delete_timer(req);
2571 
2572 	if (req->cmd_flags & REQ_DONTPREP)
2573 		blk_unprep_request(req);
2574 
2575 	blk_account_io_done(req);
2576 
2577 	if (req->end_io)
2578 		req->end_io(req, error);
2579 	else {
2580 		if (blk_bidi_rq(req))
2581 			__blk_put_request(req->next_rq->q, req->next_rq);
2582 
2583 		__blk_put_request(req->q, req);
2584 	}
2585 }
2586 EXPORT_SYMBOL(blk_finish_request);
2587 
2588 /**
2589  * blk_end_bidi_request - Complete a bidi request
2590  * @rq:         the request to complete
2591  * @error:      %0 for success, < %0 for error
2592  * @nr_bytes:   number of bytes to complete @rq
2593  * @bidi_bytes: number of bytes to complete @rq->next_rq
2594  *
2595  * Description:
2596  *     Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2597  *     Drivers that supports bidi can safely call this member for any
2598  *     type of request, bidi or uni.  In the later case @bidi_bytes is
2599  *     just ignored.
2600  *
2601  * Return:
2602  *     %false - we are done with this request
2603  *     %true  - still buffers pending for this request
2604  **/
blk_end_bidi_request(struct request * rq,int error,unsigned int nr_bytes,unsigned int bidi_bytes)2605 static bool blk_end_bidi_request(struct request *rq, int error,
2606 				 unsigned int nr_bytes, unsigned int bidi_bytes)
2607 {
2608 	struct request_queue *q = rq->q;
2609 	unsigned long flags;
2610 
2611 	if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2612 		return true;
2613 
2614 	spin_lock_irqsave(q->queue_lock, flags);
2615 	blk_finish_request(rq, error);
2616 	spin_unlock_irqrestore(q->queue_lock, flags);
2617 
2618 	return false;
2619 }
2620 
2621 /**
2622  * __blk_end_bidi_request - Complete a bidi request with queue lock held
2623  * @rq:         the request to complete
2624  * @error:      %0 for success, < %0 for error
2625  * @nr_bytes:   number of bytes to complete @rq
2626  * @bidi_bytes: number of bytes to complete @rq->next_rq
2627  *
2628  * Description:
2629  *     Identical to blk_end_bidi_request() except that queue lock is
2630  *     assumed to be locked on entry and remains so on return.
2631  *
2632  * Return:
2633  *     %false - we are done with this request
2634  *     %true  - still buffers pending for this request
2635  **/
__blk_end_bidi_request(struct request * rq,int error,unsigned int nr_bytes,unsigned int bidi_bytes)2636 bool __blk_end_bidi_request(struct request *rq, int error,
2637 				   unsigned int nr_bytes, unsigned int bidi_bytes)
2638 {
2639 	if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2640 		return true;
2641 
2642 	blk_finish_request(rq, error);
2643 
2644 	return false;
2645 }
2646 
2647 /**
2648  * blk_end_request - Helper function for drivers to complete the request.
2649  * @rq:       the request being processed
2650  * @error:    %0 for success, < %0 for error
2651  * @nr_bytes: number of bytes to complete
2652  *
2653  * Description:
2654  *     Ends I/O on a number of bytes attached to @rq.
2655  *     If @rq has leftover, sets it up for the next range of segments.
2656  *
2657  * Return:
2658  *     %false - we are done with this request
2659  *     %true  - still buffers pending for this request
2660  **/
blk_end_request(struct request * rq,int error,unsigned int nr_bytes)2661 bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
2662 {
2663 	return blk_end_bidi_request(rq, error, nr_bytes, 0);
2664 }
2665 EXPORT_SYMBOL(blk_end_request);
2666 
2667 /**
2668  * blk_end_request_all - Helper function for drives to finish the request.
2669  * @rq: the request to finish
2670  * @error: %0 for success, < %0 for error
2671  *
2672  * Description:
2673  *     Completely finish @rq.
2674  */
blk_end_request_all(struct request * rq,int error)2675 void blk_end_request_all(struct request *rq, int error)
2676 {
2677 	bool pending;
2678 	unsigned int bidi_bytes = 0;
2679 
2680 	if (unlikely(blk_bidi_rq(rq)))
2681 		bidi_bytes = blk_rq_bytes(rq->next_rq);
2682 
2683 	pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2684 	BUG_ON(pending);
2685 }
2686 EXPORT_SYMBOL(blk_end_request_all);
2687 
2688 /**
2689  * blk_end_request_cur - Helper function to finish the current request chunk.
2690  * @rq: the request to finish the current chunk for
2691  * @error: %0 for success, < %0 for error
2692  *
2693  * Description:
2694  *     Complete the current consecutively mapped chunk from @rq.
2695  *
2696  * Return:
2697  *     %false - we are done with this request
2698  *     %true  - still buffers pending for this request
2699  */
blk_end_request_cur(struct request * rq,int error)2700 bool blk_end_request_cur(struct request *rq, int error)
2701 {
2702 	return blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2703 }
2704 EXPORT_SYMBOL(blk_end_request_cur);
2705 
2706 /**
2707  * blk_end_request_err - Finish a request till the next failure boundary.
2708  * @rq: the request to finish till the next failure boundary for
2709  * @error: must be negative errno
2710  *
2711  * Description:
2712  *     Complete @rq till the next failure boundary.
2713  *
2714  * Return:
2715  *     %false - we are done with this request
2716  *     %true  - still buffers pending for this request
2717  */
blk_end_request_err(struct request * rq,int error)2718 bool blk_end_request_err(struct request *rq, int error)
2719 {
2720 	WARN_ON(error >= 0);
2721 	return blk_end_request(rq, error, blk_rq_err_bytes(rq));
2722 }
2723 EXPORT_SYMBOL_GPL(blk_end_request_err);
2724 
2725 /**
2726  * __blk_end_request - Helper function for drivers to complete the request.
2727  * @rq:       the request being processed
2728  * @error:    %0 for success, < %0 for error
2729  * @nr_bytes: number of bytes to complete
2730  *
2731  * Description:
2732  *     Must be called with queue lock held unlike blk_end_request().
2733  *
2734  * Return:
2735  *     %false - we are done with this request
2736  *     %true  - still buffers pending for this request
2737  **/
__blk_end_request(struct request * rq,int error,unsigned int nr_bytes)2738 bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
2739 {
2740 	return __blk_end_bidi_request(rq, error, nr_bytes, 0);
2741 }
2742 EXPORT_SYMBOL(__blk_end_request);
2743 
2744 /**
2745  * __blk_end_request_all - Helper function for drives to finish the request.
2746  * @rq: the request to finish
2747  * @error: %0 for success, < %0 for error
2748  *
2749  * Description:
2750  *     Completely finish @rq.  Must be called with queue lock held.
2751  */
__blk_end_request_all(struct request * rq,int error)2752 void __blk_end_request_all(struct request *rq, int error)
2753 {
2754 	bool pending;
2755 	unsigned int bidi_bytes = 0;
2756 
2757 	if (unlikely(blk_bidi_rq(rq)))
2758 		bidi_bytes = blk_rq_bytes(rq->next_rq);
2759 
2760 	pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2761 	BUG_ON(pending);
2762 }
2763 EXPORT_SYMBOL(__blk_end_request_all);
2764 
2765 /**
2766  * __blk_end_request_cur - Helper function to finish the current request chunk.
2767  * @rq: the request to finish the current chunk for
2768  * @error: %0 for success, < %0 for error
2769  *
2770  * Description:
2771  *     Complete the current consecutively mapped chunk from @rq.  Must
2772  *     be called with queue lock held.
2773  *
2774  * Return:
2775  *     %false - we are done with this request
2776  *     %true  - still buffers pending for this request
2777  */
__blk_end_request_cur(struct request * rq,int error)2778 bool __blk_end_request_cur(struct request *rq, int error)
2779 {
2780 	return __blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2781 }
2782 EXPORT_SYMBOL(__blk_end_request_cur);
2783 
2784 /**
2785  * __blk_end_request_err - Finish a request till the next failure boundary.
2786  * @rq: the request to finish till the next failure boundary for
2787  * @error: must be negative errno
2788  *
2789  * Description:
2790  *     Complete @rq till the next failure boundary.  Must be called
2791  *     with queue lock held.
2792  *
2793  * Return:
2794  *     %false - we are done with this request
2795  *     %true  - still buffers pending for this request
2796  */
__blk_end_request_err(struct request * rq,int error)2797 bool __blk_end_request_err(struct request *rq, int error)
2798 {
2799 	WARN_ON(error >= 0);
2800 	return __blk_end_request(rq, error, blk_rq_err_bytes(rq));
2801 }
2802 EXPORT_SYMBOL_GPL(__blk_end_request_err);
2803 
blk_rq_bio_prep(struct request_queue * q,struct request * rq,struct bio * bio)2804 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
2805 		     struct bio *bio)
2806 {
2807 	/* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */
2808 	rq->cmd_flags |= bio->bi_rw & REQ_WRITE;
2809 
2810 	if (bio_has_data(bio))
2811 		rq->nr_phys_segments = bio_phys_segments(q, bio);
2812 
2813 	rq->__data_len = bio->bi_iter.bi_size;
2814 	rq->bio = rq->biotail = bio;
2815 
2816 	if (bio->bi_bdev)
2817 		rq->rq_disk = bio->bi_bdev->bd_disk;
2818 }
2819 
2820 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
2821 /**
2822  * rq_flush_dcache_pages - Helper function to flush all pages in a request
2823  * @rq: the request to be flushed
2824  *
2825  * Description:
2826  *     Flush all pages in @rq.
2827  */
rq_flush_dcache_pages(struct request * rq)2828 void rq_flush_dcache_pages(struct request *rq)
2829 {
2830 	struct req_iterator iter;
2831 	struct bio_vec bvec;
2832 
2833 	rq_for_each_segment(bvec, rq, iter)
2834 		flush_dcache_page(bvec.bv_page);
2835 }
2836 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
2837 #endif
2838 
2839 /**
2840  * blk_lld_busy - Check if underlying low-level drivers of a device are busy
2841  * @q : the queue of the device being checked
2842  *
2843  * Description:
2844  *    Check if underlying low-level drivers of a device are busy.
2845  *    If the drivers want to export their busy state, they must set own
2846  *    exporting function using blk_queue_lld_busy() first.
2847  *
2848  *    Basically, this function is used only by request stacking drivers
2849  *    to stop dispatching requests to underlying devices when underlying
2850  *    devices are busy.  This behavior helps more I/O merging on the queue
2851  *    of the request stacking driver and prevents I/O throughput regression
2852  *    on burst I/O load.
2853  *
2854  * Return:
2855  *    0 - Not busy (The request stacking driver should dispatch request)
2856  *    1 - Busy (The request stacking driver should stop dispatching request)
2857  */
blk_lld_busy(struct request_queue * q)2858 int blk_lld_busy(struct request_queue *q)
2859 {
2860 	if (q->lld_busy_fn)
2861 		return q->lld_busy_fn(q);
2862 
2863 	return 0;
2864 }
2865 EXPORT_SYMBOL_GPL(blk_lld_busy);
2866 
2867 /**
2868  * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
2869  * @rq: the clone request to be cleaned up
2870  *
2871  * Description:
2872  *     Free all bios in @rq for a cloned request.
2873  */
blk_rq_unprep_clone(struct request * rq)2874 void blk_rq_unprep_clone(struct request *rq)
2875 {
2876 	struct bio *bio;
2877 
2878 	while ((bio = rq->bio) != NULL) {
2879 		rq->bio = bio->bi_next;
2880 
2881 		bio_put(bio);
2882 	}
2883 }
2884 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
2885 
2886 /*
2887  * Copy attributes of the original request to the clone request.
2888  * The actual data parts (e.g. ->cmd, ->sense) are not copied.
2889  */
__blk_rq_prep_clone(struct request * dst,struct request * src)2890 static void __blk_rq_prep_clone(struct request *dst, struct request *src)
2891 {
2892 	dst->cpu = src->cpu;
2893 	dst->cmd_flags = (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE;
2894 	dst->cmd_type = src->cmd_type;
2895 	dst->__sector = blk_rq_pos(src);
2896 	dst->__data_len = blk_rq_bytes(src);
2897 	dst->nr_phys_segments = src->nr_phys_segments;
2898 	dst->ioprio = src->ioprio;
2899 	dst->extra_len = src->extra_len;
2900 }
2901 
2902 /**
2903  * blk_rq_prep_clone - Helper function to setup clone request
2904  * @rq: the request to be setup
2905  * @rq_src: original request to be cloned
2906  * @bs: bio_set that bios for clone are allocated from
2907  * @gfp_mask: memory allocation mask for bio
2908  * @bio_ctr: setup function to be called for each clone bio.
2909  *           Returns %0 for success, non %0 for failure.
2910  * @data: private data to be passed to @bio_ctr
2911  *
2912  * Description:
2913  *     Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
2914  *     The actual data parts of @rq_src (e.g. ->cmd, ->sense)
2915  *     are not copied, and copying such parts is the caller's responsibility.
2916  *     Also, pages which the original bios are pointing to are not copied
2917  *     and the cloned bios just point same pages.
2918  *     So cloned bios must be completed before original bios, which means
2919  *     the caller must complete @rq before @rq_src.
2920  */
blk_rq_prep_clone(struct request * rq,struct request * rq_src,struct bio_set * bs,gfp_t gfp_mask,int (* bio_ctr)(struct bio *,struct bio *,void *),void * data)2921 int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
2922 		      struct bio_set *bs, gfp_t gfp_mask,
2923 		      int (*bio_ctr)(struct bio *, struct bio *, void *),
2924 		      void *data)
2925 {
2926 	struct bio *bio, *bio_src;
2927 
2928 	if (!bs)
2929 		bs = fs_bio_set;
2930 
2931 	blk_rq_init(NULL, rq);
2932 
2933 	__rq_for_each_bio(bio_src, rq_src) {
2934 		bio = bio_clone_fast(bio_src, gfp_mask, bs);
2935 		if (!bio)
2936 			goto free_and_out;
2937 
2938 		if (bio_ctr && bio_ctr(bio, bio_src, data))
2939 			goto free_and_out;
2940 
2941 		if (rq->bio) {
2942 			rq->biotail->bi_next = bio;
2943 			rq->biotail = bio;
2944 		} else
2945 			rq->bio = rq->biotail = bio;
2946 	}
2947 
2948 	__blk_rq_prep_clone(rq, rq_src);
2949 
2950 	return 0;
2951 
2952 free_and_out:
2953 	if (bio)
2954 		bio_put(bio);
2955 	blk_rq_unprep_clone(rq);
2956 
2957 	return -ENOMEM;
2958 }
2959 EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
2960 
kblockd_schedule_work(struct work_struct * work)2961 int kblockd_schedule_work(struct work_struct *work)
2962 {
2963 	return queue_work(kblockd_workqueue, work);
2964 }
2965 EXPORT_SYMBOL(kblockd_schedule_work);
2966 
kblockd_schedule_delayed_work(struct delayed_work * dwork,unsigned long delay)2967 int kblockd_schedule_delayed_work(struct delayed_work *dwork,
2968 				  unsigned long delay)
2969 {
2970 	return queue_delayed_work(kblockd_workqueue, dwork, delay);
2971 }
2972 EXPORT_SYMBOL(kblockd_schedule_delayed_work);
2973 
kblockd_schedule_delayed_work_on(int cpu,struct delayed_work * dwork,unsigned long delay)2974 int kblockd_schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
2975 				     unsigned long delay)
2976 {
2977 	return queue_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
2978 }
2979 EXPORT_SYMBOL(kblockd_schedule_delayed_work_on);
2980 
2981 /**
2982  * blk_start_plug - initialize blk_plug and track it inside the task_struct
2983  * @plug:	The &struct blk_plug that needs to be initialized
2984  *
2985  * Description:
2986  *   Tracking blk_plug inside the task_struct will help with auto-flushing the
2987  *   pending I/O should the task end up blocking between blk_start_plug() and
2988  *   blk_finish_plug(). This is important from a performance perspective, but
2989  *   also ensures that we don't deadlock. For instance, if the task is blocking
2990  *   for a memory allocation, memory reclaim could end up wanting to free a
2991  *   page belonging to that request that is currently residing in our private
2992  *   plug. By flushing the pending I/O when the process goes to sleep, we avoid
2993  *   this kind of deadlock.
2994  */
blk_start_plug(struct blk_plug * plug)2995 void blk_start_plug(struct blk_plug *plug)
2996 {
2997 	struct task_struct *tsk = current;
2998 
2999 	INIT_LIST_HEAD(&plug->list);
3000 	INIT_LIST_HEAD(&plug->mq_list);
3001 	INIT_LIST_HEAD(&plug->cb_list);
3002 
3003 	/*
3004 	 * If this is a nested plug, don't actually assign it. It will be
3005 	 * flushed on its own.
3006 	 */
3007 	if (!tsk->plug) {
3008 		/*
3009 		 * Store ordering should not be needed here, since a potential
3010 		 * preempt will imply a full memory barrier
3011 		 */
3012 		tsk->plug = plug;
3013 	}
3014 }
3015 EXPORT_SYMBOL(blk_start_plug);
3016 
plug_rq_cmp(void * priv,struct list_head * a,struct list_head * b)3017 static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
3018 {
3019 	struct request *rqa = container_of(a, struct request, queuelist);
3020 	struct request *rqb = container_of(b, struct request, queuelist);
3021 
3022 	return !(rqa->q < rqb->q ||
3023 		(rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb)));
3024 }
3025 
3026 /*
3027  * If 'from_schedule' is true, then postpone the dispatch of requests
3028  * until a safe kblockd context. We due this to avoid accidental big
3029  * additional stack usage in driver dispatch, in places where the originally
3030  * plugger did not intend it.
3031  */
queue_unplugged(struct request_queue * q,unsigned int depth,bool from_schedule)3032 static void queue_unplugged(struct request_queue *q, unsigned int depth,
3033 			    bool from_schedule)
3034 	__releases(q->queue_lock)
3035 {
3036 	trace_block_unplug(q, depth, !from_schedule);
3037 
3038 	if (from_schedule)
3039 		blk_run_queue_async(q);
3040 	else
3041 		__blk_run_queue(q);
3042 	spin_unlock(q->queue_lock);
3043 }
3044 
flush_plug_callbacks(struct blk_plug * plug,bool from_schedule)3045 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
3046 {
3047 	LIST_HEAD(callbacks);
3048 
3049 	while (!list_empty(&plug->cb_list)) {
3050 		list_splice_init(&plug->cb_list, &callbacks);
3051 
3052 		while (!list_empty(&callbacks)) {
3053 			struct blk_plug_cb *cb = list_first_entry(&callbacks,
3054 							  struct blk_plug_cb,
3055 							  list);
3056 			list_del(&cb->list);
3057 			cb->callback(cb, from_schedule);
3058 		}
3059 	}
3060 }
3061 
blk_check_plugged(blk_plug_cb_fn unplug,void * data,int size)3062 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
3063 				      int size)
3064 {
3065 	struct blk_plug *plug = current->plug;
3066 	struct blk_plug_cb *cb;
3067 
3068 	if (!plug)
3069 		return NULL;
3070 
3071 	list_for_each_entry(cb, &plug->cb_list, list)
3072 		if (cb->callback == unplug && cb->data == data)
3073 			return cb;
3074 
3075 	/* Not currently on the callback list */
3076 	BUG_ON(size < sizeof(*cb));
3077 	cb = kzalloc(size, GFP_ATOMIC);
3078 	if (cb) {
3079 		cb->data = data;
3080 		cb->callback = unplug;
3081 		list_add(&cb->list, &plug->cb_list);
3082 	}
3083 	return cb;
3084 }
3085 EXPORT_SYMBOL(blk_check_plugged);
3086 
blk_flush_plug_list(struct blk_plug * plug,bool from_schedule)3087 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
3088 {
3089 	struct request_queue *q;
3090 	unsigned long flags;
3091 	struct request *rq;
3092 	LIST_HEAD(list);
3093 	unsigned int depth;
3094 
3095 	flush_plug_callbacks(plug, from_schedule);
3096 
3097 	if (!list_empty(&plug->mq_list))
3098 		blk_mq_flush_plug_list(plug, from_schedule);
3099 
3100 	if (list_empty(&plug->list))
3101 		return;
3102 
3103 	list_splice_init(&plug->list, &list);
3104 
3105 	list_sort(NULL, &list, plug_rq_cmp);
3106 
3107 	q = NULL;
3108 	depth = 0;
3109 
3110 	/*
3111 	 * Save and disable interrupts here, to avoid doing it for every
3112 	 * queue lock we have to take.
3113 	 */
3114 	local_irq_save(flags);
3115 	while (!list_empty(&list)) {
3116 		rq = list_entry_rq(list.next);
3117 		list_del_init(&rq->queuelist);
3118 		BUG_ON(!rq->q);
3119 		if (rq->q != q) {
3120 			/*
3121 			 * This drops the queue lock
3122 			 */
3123 			if (q)
3124 				queue_unplugged(q, depth, from_schedule);
3125 			q = rq->q;
3126 			depth = 0;
3127 			spin_lock(q->queue_lock);
3128 		}
3129 
3130 		/*
3131 		 * Short-circuit if @q is dead
3132 		 */
3133 		if (unlikely(blk_queue_dying(q))) {
3134 			__blk_end_request_all(rq, -ENODEV);
3135 			continue;
3136 		}
3137 
3138 		/*
3139 		 * rq is already accounted, so use raw insert
3140 		 */
3141 		if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA))
3142 			__elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
3143 		else
3144 			__elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);
3145 
3146 		depth++;
3147 	}
3148 
3149 	/*
3150 	 * This drops the queue lock
3151 	 */
3152 	if (q)
3153 		queue_unplugged(q, depth, from_schedule);
3154 
3155 	local_irq_restore(flags);
3156 }
3157 
blk_finish_plug(struct blk_plug * plug)3158 void blk_finish_plug(struct blk_plug *plug)
3159 {
3160 	blk_flush_plug_list(plug, false);
3161 
3162 	if (plug == current->plug)
3163 		current->plug = NULL;
3164 }
3165 EXPORT_SYMBOL(blk_finish_plug);
3166 
3167 #ifdef CONFIG_PM_RUNTIME
3168 /**
3169  * blk_pm_runtime_init - Block layer runtime PM initialization routine
3170  * @q: the queue of the device
3171  * @dev: the device the queue belongs to
3172  *
3173  * Description:
3174  *    Initialize runtime-PM-related fields for @q and start auto suspend for
3175  *    @dev. Drivers that want to take advantage of request-based runtime PM
3176  *    should call this function after @dev has been initialized, and its
3177  *    request queue @q has been allocated, and runtime PM for it can not happen
3178  *    yet(either due to disabled/forbidden or its usage_count > 0). In most
3179  *    cases, driver should call this function before any I/O has taken place.
3180  *
3181  *    This function takes care of setting up using auto suspend for the device,
3182  *    the autosuspend delay is set to -1 to make runtime suspend impossible
3183  *    until an updated value is either set by user or by driver. Drivers do
3184  *    not need to touch other autosuspend settings.
3185  *
3186  *    The block layer runtime PM is request based, so only works for drivers
3187  *    that use request as their IO unit instead of those directly use bio's.
3188  */
blk_pm_runtime_init(struct request_queue * q,struct device * dev)3189 void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
3190 {
3191 	q->dev = dev;
3192 	q->rpm_status = RPM_ACTIVE;
3193 	pm_runtime_set_autosuspend_delay(q->dev, -1);
3194 	pm_runtime_use_autosuspend(q->dev);
3195 }
3196 EXPORT_SYMBOL(blk_pm_runtime_init);
3197 
3198 /**
3199  * blk_pre_runtime_suspend - Pre runtime suspend check
3200  * @q: the queue of the device
3201  *
3202  * Description:
3203  *    This function will check if runtime suspend is allowed for the device
3204  *    by examining if there are any requests pending in the queue. If there
3205  *    are requests pending, the device can not be runtime suspended; otherwise,
3206  *    the queue's status will be updated to SUSPENDING and the driver can
3207  *    proceed to suspend the device.
3208  *
3209  *    For the not allowed case, we mark last busy for the device so that
3210  *    runtime PM core will try to autosuspend it some time later.
3211  *
3212  *    This function should be called near the start of the device's
3213  *    runtime_suspend callback.
3214  *
3215  * Return:
3216  *    0		- OK to runtime suspend the device
3217  *    -EBUSY	- Device should not be runtime suspended
3218  */
blk_pre_runtime_suspend(struct request_queue * q)3219 int blk_pre_runtime_suspend(struct request_queue *q)
3220 {
3221 	int ret = 0;
3222 
3223 	spin_lock_irq(q->queue_lock);
3224 	if (q->nr_pending) {
3225 		ret = -EBUSY;
3226 		pm_runtime_mark_last_busy(q->dev);
3227 	} else {
3228 		q->rpm_status = RPM_SUSPENDING;
3229 	}
3230 	spin_unlock_irq(q->queue_lock);
3231 	return ret;
3232 }
3233 EXPORT_SYMBOL(blk_pre_runtime_suspend);
3234 
3235 /**
3236  * blk_post_runtime_suspend - Post runtime suspend processing
3237  * @q: the queue of the device
3238  * @err: return value of the device's runtime_suspend function
3239  *
3240  * Description:
3241  *    Update the queue's runtime status according to the return value of the
3242  *    device's runtime suspend function and mark last busy for the device so
3243  *    that PM core will try to auto suspend the device at a later time.
3244  *
3245  *    This function should be called near the end of the device's
3246  *    runtime_suspend callback.
3247  */
blk_post_runtime_suspend(struct request_queue * q,int err)3248 void blk_post_runtime_suspend(struct request_queue *q, int err)
3249 {
3250 	spin_lock_irq(q->queue_lock);
3251 	if (!err) {
3252 		q->rpm_status = RPM_SUSPENDED;
3253 	} else {
3254 		q->rpm_status = RPM_ACTIVE;
3255 		pm_runtime_mark_last_busy(q->dev);
3256 	}
3257 	spin_unlock_irq(q->queue_lock);
3258 }
3259 EXPORT_SYMBOL(blk_post_runtime_suspend);
3260 
3261 /**
3262  * blk_pre_runtime_resume - Pre runtime resume processing
3263  * @q: the queue of the device
3264  *
3265  * Description:
3266  *    Update the queue's runtime status to RESUMING in preparation for the
3267  *    runtime resume of the device.
3268  *
3269  *    This function should be called near the start of the device's
3270  *    runtime_resume callback.
3271  */
blk_pre_runtime_resume(struct request_queue * q)3272 void blk_pre_runtime_resume(struct request_queue *q)
3273 {
3274 	spin_lock_irq(q->queue_lock);
3275 	q->rpm_status = RPM_RESUMING;
3276 	spin_unlock_irq(q->queue_lock);
3277 }
3278 EXPORT_SYMBOL(blk_pre_runtime_resume);
3279 
3280 /**
3281  * blk_post_runtime_resume - Post runtime resume processing
3282  * @q: the queue of the device
3283  * @err: return value of the device's runtime_resume function
3284  *
3285  * Description:
3286  *    Update the queue's runtime status according to the return value of the
3287  *    device's runtime_resume function. If it is successfully resumed, process
3288  *    the requests that are queued into the device's queue when it is resuming
3289  *    and then mark last busy and initiate autosuspend for it.
3290  *
3291  *    This function should be called near the end of the device's
3292  *    runtime_resume callback.
3293  */
blk_post_runtime_resume(struct request_queue * q,int err)3294 void blk_post_runtime_resume(struct request_queue *q, int err)
3295 {
3296 	spin_lock_irq(q->queue_lock);
3297 	if (!err) {
3298 		q->rpm_status = RPM_ACTIVE;
3299 		__blk_run_queue(q);
3300 		pm_runtime_mark_last_busy(q->dev);
3301 		pm_request_autosuspend(q->dev);
3302 	} else {
3303 		q->rpm_status = RPM_SUSPENDED;
3304 	}
3305 	spin_unlock_irq(q->queue_lock);
3306 }
3307 EXPORT_SYMBOL(blk_post_runtime_resume);
3308 #endif
3309 
blk_dev_init(void)3310 int __init blk_dev_init(void)
3311 {
3312 	BUILD_BUG_ON(__REQ_NR_BITS > 8 *
3313 			sizeof(((struct request *)0)->cmd_flags));
3314 
3315 	/* used for unplugging and affects IO latency/throughput - HIGHPRI */
3316 	kblockd_workqueue = alloc_workqueue("kblockd",
3317 					    WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
3318 	if (!kblockd_workqueue)
3319 		panic("Failed to create kblockd\n");
3320 
3321 	request_cachep = kmem_cache_create("blkdev_requests",
3322 			sizeof(struct request), 0, SLAB_PANIC, NULL);
3323 
3324 	blk_requestq_cachep = kmem_cache_create("blkdev_queue",
3325 			sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
3326 
3327 	return 0;
3328 }
3329 
3330 /*
3331  * Blk IO latency support. We want this to be as cheap as possible, so doing
3332  * this lockless (and avoiding atomics), a few off by a few errors in this
3333  * code is not harmful, and we don't want to do anything that is
3334  * perf-impactful.
3335  * TODO : If necessary, we can make the histograms per-cpu and aggregate
3336  * them when printing them out.
3337  */
3338 ssize_t
blk_latency_hist_show(char * name,struct io_latency_state * s,char * buf,int buf_size)3339 blk_latency_hist_show(char* name, struct io_latency_state *s, char *buf,
3340 		int buf_size)
3341 {
3342 	int i;
3343 	int bytes_written = 0;
3344 	u_int64_t num_elem, elem;
3345 	int pct;
3346 	u_int64_t average;
3347 
3348        num_elem = s->latency_elems;
3349        if (num_elem > 0) {
3350 	       average = div64_u64(s->latency_sum, s->latency_elems);
3351 	       bytes_written += scnprintf(buf + bytes_written,
3352 			       buf_size - bytes_written,
3353 			       "IO svc_time %s Latency Histogram (n = %llu,"
3354 			       " average = %llu):\n", name, num_elem, average);
3355 	       for (i = 0;
3356 		    i < ARRAY_SIZE(latency_x_axis_us);
3357 		    i++) {
3358 		       elem = s->latency_y_axis[i];
3359 		       pct = div64_u64(elem * 100, num_elem);
3360 		       bytes_written += scnprintf(buf + bytes_written,
3361 				       PAGE_SIZE - bytes_written,
3362 				       "\t< %6lluus%15llu%15d%%\n",
3363 				       latency_x_axis_us[i],
3364 				       elem, pct);
3365 	       }
3366 	       /* Last element in y-axis table is overflow */
3367 	       elem = s->latency_y_axis[i];
3368 	       pct = div64_u64(elem * 100, num_elem);
3369 	       bytes_written += scnprintf(buf + bytes_written,
3370 			       PAGE_SIZE - bytes_written,
3371 			       "\t>=%6lluus%15llu%15d%%\n",
3372 			       latency_x_axis_us[i - 1], elem, pct);
3373 	}
3374 
3375 	return bytes_written;
3376 }
3377 EXPORT_SYMBOL(blk_latency_hist_show);
3378