xref: /openbmc/linux/drivers/md/dm.c (revision be35f486108227e10fe5d96fd42fb2b344c59983)
1 /*
2  * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
3  * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
4  *
5  * This file is released under the GPL.
6  */
7 
8 #include "dm.h"
9 #include "dm-uevent.h"
10 
11 #include <linux/init.h>
12 #include <linux/module.h>
13 #include <linux/mutex.h>
14 #include <linux/moduleparam.h>
15 #include <linux/blkpg.h>
16 #include <linux/bio.h>
17 #include <linux/mempool.h>
18 #include <linux/slab.h>
19 #include <linux/idr.h>
20 #include <linux/hdreg.h>
21 #include <linux/delay.h>
22 
23 #include <trace/events/block.h>
24 
25 #define DM_MSG_PREFIX "core"
26 
27 #ifdef CONFIG_PRINTK
28 /*
29  * ratelimit state to be used in DMXXX_LIMIT().
30  */
31 DEFINE_RATELIMIT_STATE(dm_ratelimit_state,
32 		       DEFAULT_RATELIMIT_INTERVAL,
33 		       DEFAULT_RATELIMIT_BURST);
34 EXPORT_SYMBOL(dm_ratelimit_state);
35 #endif
36 
37 /*
38  * Cookies are numeric values sent with CHANGE and REMOVE
39  * uevents while resuming, removing or renaming the device.
40  */
41 #define DM_COOKIE_ENV_VAR_NAME "DM_COOKIE"
42 #define DM_COOKIE_LENGTH 24
43 
44 static const char *_name = DM_NAME;
45 
46 static unsigned int major = 0;
47 static unsigned int _major = 0;
48 
49 static DEFINE_IDR(_minor_idr);
50 
51 static DEFINE_SPINLOCK(_minor_lock);
52 
53 static void do_deferred_remove(struct work_struct *w);
54 
55 static DECLARE_WORK(deferred_remove_work, do_deferred_remove);
56 
57 /*
58  * For bio-based dm.
59  * One of these is allocated per bio.
60  */
61 struct dm_io {
62 	struct mapped_device *md;
63 	int error;
64 	atomic_t io_count;
65 	struct bio *bio;
66 	unsigned long start_time;
67 	spinlock_t endio_lock;
68 	struct dm_stats_aux stats_aux;
69 };
70 
71 /*
72  * For request-based dm.
73  * One of these is allocated per request.
74  */
75 struct dm_rq_target_io {
76 	struct mapped_device *md;
77 	struct dm_target *ti;
78 	struct request *orig, clone;
79 	int error;
80 	union map_info info;
81 };
82 
83 /*
84  * For request-based dm - the bio clones we allocate are embedded in these
85  * structs.
86  *
87  * We allocate these with bio_alloc_bioset, using the front_pad parameter when
88  * the bioset is created - this means the bio has to come at the end of the
89  * struct.
90  */
91 struct dm_rq_clone_bio_info {
92 	struct bio *orig;
93 	struct dm_rq_target_io *tio;
94 	struct bio clone;
95 };
96 
97 union map_info *dm_get_mapinfo(struct bio *bio)
98 {
99 	if (bio && bio->bi_private)
100 		return &((struct dm_target_io *)bio->bi_private)->info;
101 	return NULL;
102 }
103 
104 union map_info *dm_get_rq_mapinfo(struct request *rq)
105 {
106 	if (rq && rq->end_io_data)
107 		return &((struct dm_rq_target_io *)rq->end_io_data)->info;
108 	return NULL;
109 }
110 EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo);
111 
112 #define MINOR_ALLOCED ((void *)-1)
113 
114 /*
115  * Bits for the md->flags field.
116  */
117 #define DMF_BLOCK_IO_FOR_SUSPEND 0
118 #define DMF_SUSPENDED 1
119 #define DMF_FROZEN 2
120 #define DMF_FREEING 3
121 #define DMF_DELETING 4
122 #define DMF_NOFLUSH_SUSPENDING 5
123 #define DMF_MERGE_IS_OPTIONAL 6
124 #define DMF_DEFERRED_REMOVE 7
125 
126 /*
127  * A dummy definition to make RCU happy.
128  * struct dm_table should never be dereferenced in this file.
129  */
130 struct dm_table {
131 	int undefined__;
132 };
133 
134 /*
135  * Work processed by per-device workqueue.
136  */
137 struct mapped_device {
138 	struct srcu_struct io_barrier;
139 	struct mutex suspend_lock;
140 	atomic_t holders;
141 	atomic_t open_count;
142 
143 	/*
144 	 * The current mapping.
145 	 * Use dm_get_live_table{_fast} or take suspend_lock for
146 	 * dereference.
147 	 */
148 	struct dm_table *map;
149 
150 	unsigned long flags;
151 
152 	struct request_queue *queue;
153 	unsigned type;
154 	/* Protect queue and type against concurrent access. */
155 	struct mutex type_lock;
156 
157 	struct target_type *immutable_target_type;
158 
159 	struct gendisk *disk;
160 	char name[16];
161 
162 	void *interface_ptr;
163 
164 	/*
165 	 * A list of ios that arrived while we were suspended.
166 	 */
167 	atomic_t pending[2];
168 	wait_queue_head_t wait;
169 	struct work_struct work;
170 	struct bio_list deferred;
171 	spinlock_t deferred_lock;
172 
173 	/*
174 	 * Processing queue (flush)
175 	 */
176 	struct workqueue_struct *wq;
177 
178 	/*
179 	 * io objects are allocated from here.
180 	 */
181 	mempool_t *io_pool;
182 
183 	struct bio_set *bs;
184 
185 	/*
186 	 * Event handling.
187 	 */
188 	atomic_t event_nr;
189 	wait_queue_head_t eventq;
190 	atomic_t uevent_seq;
191 	struct list_head uevent_list;
192 	spinlock_t uevent_lock; /* Protect access to uevent_list */
193 
194 	/*
195 	 * freeze/thaw support require holding onto a super block
196 	 */
197 	struct super_block *frozen_sb;
198 	struct block_device *bdev;
199 
200 	/* forced geometry settings */
201 	struct hd_geometry geometry;
202 
203 	/* sysfs handle */
204 	struct kobject kobj;
205 
206 	/* wait until the kobject is released */
207 	struct completion kobj_completion;
208 
209 	/* zero-length flush that will be cloned and submitted to targets */
210 	struct bio flush_bio;
211 
212 	struct dm_stats stats;
213 };
214 
215 /*
216  * For mempools pre-allocation at the table loading time.
217  */
218 struct dm_md_mempools {
219 	mempool_t *io_pool;
220 	struct bio_set *bs;
221 };
222 
223 #define RESERVED_BIO_BASED_IOS		16
224 #define RESERVED_REQUEST_BASED_IOS	256
225 #define RESERVED_MAX_IOS		1024
226 static struct kmem_cache *_io_cache;
227 static struct kmem_cache *_rq_tio_cache;
228 
229 /*
230  * Bio-based DM's mempools' reserved IOs set by the user.
231  */
232 static unsigned reserved_bio_based_ios = RESERVED_BIO_BASED_IOS;
233 
234 /*
235  * Request-based DM's mempools' reserved IOs set by the user.
236  */
237 static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS;
238 
239 static unsigned __dm_get_reserved_ios(unsigned *reserved_ios,
240 				      unsigned def, unsigned max)
241 {
242 	unsigned ios = ACCESS_ONCE(*reserved_ios);
243 	unsigned modified_ios = 0;
244 
245 	if (!ios)
246 		modified_ios = def;
247 	else if (ios > max)
248 		modified_ios = max;
249 
250 	if (modified_ios) {
251 		(void)cmpxchg(reserved_ios, ios, modified_ios);
252 		ios = modified_ios;
253 	}
254 
255 	return ios;
256 }
257 
258 unsigned dm_get_reserved_bio_based_ios(void)
259 {
260 	return __dm_get_reserved_ios(&reserved_bio_based_ios,
261 				     RESERVED_BIO_BASED_IOS, RESERVED_MAX_IOS);
262 }
263 EXPORT_SYMBOL_GPL(dm_get_reserved_bio_based_ios);
264 
265 unsigned dm_get_reserved_rq_based_ios(void)
266 {
267 	return __dm_get_reserved_ios(&reserved_rq_based_ios,
268 				     RESERVED_REQUEST_BASED_IOS, RESERVED_MAX_IOS);
269 }
270 EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios);
271 
272 static int __init local_init(void)
273 {
274 	int r = -ENOMEM;
275 
276 	/* allocate a slab for the dm_ios */
277 	_io_cache = KMEM_CACHE(dm_io, 0);
278 	if (!_io_cache)
279 		return r;
280 
281 	_rq_tio_cache = KMEM_CACHE(dm_rq_target_io, 0);
282 	if (!_rq_tio_cache)
283 		goto out_free_io_cache;
284 
285 	r = dm_uevent_init();
286 	if (r)
287 		goto out_free_rq_tio_cache;
288 
289 	_major = major;
290 	r = register_blkdev(_major, _name);
291 	if (r < 0)
292 		goto out_uevent_exit;
293 
294 	if (!_major)
295 		_major = r;
296 
297 	return 0;
298 
299 out_uevent_exit:
300 	dm_uevent_exit();
301 out_free_rq_tio_cache:
302 	kmem_cache_destroy(_rq_tio_cache);
303 out_free_io_cache:
304 	kmem_cache_destroy(_io_cache);
305 
306 	return r;
307 }
308 
309 static void local_exit(void)
310 {
311 	flush_scheduled_work();
312 
313 	kmem_cache_destroy(_rq_tio_cache);
314 	kmem_cache_destroy(_io_cache);
315 	unregister_blkdev(_major, _name);
316 	dm_uevent_exit();
317 
318 	_major = 0;
319 
320 	DMINFO("cleaned up");
321 }
322 
323 static int (*_inits[])(void) __initdata = {
324 	local_init,
325 	dm_target_init,
326 	dm_linear_init,
327 	dm_stripe_init,
328 	dm_io_init,
329 	dm_kcopyd_init,
330 	dm_interface_init,
331 	dm_statistics_init,
332 };
333 
334 static void (*_exits[])(void) = {
335 	local_exit,
336 	dm_target_exit,
337 	dm_linear_exit,
338 	dm_stripe_exit,
339 	dm_io_exit,
340 	dm_kcopyd_exit,
341 	dm_interface_exit,
342 	dm_statistics_exit,
343 };
344 
345 static int __init dm_init(void)
346 {
347 	const int count = ARRAY_SIZE(_inits);
348 
349 	int r, i;
350 
351 	for (i = 0; i < count; i++) {
352 		r = _inits[i]();
353 		if (r)
354 			goto bad;
355 	}
356 
357 	return 0;
358 
359       bad:
360 	while (i--)
361 		_exits[i]();
362 
363 	return r;
364 }
365 
366 static void __exit dm_exit(void)
367 {
368 	int i = ARRAY_SIZE(_exits);
369 
370 	while (i--)
371 		_exits[i]();
372 
373 	/*
374 	 * Should be empty by this point.
375 	 */
376 	idr_destroy(&_minor_idr);
377 }
378 
379 /*
380  * Block device functions
381  */
382 int dm_deleting_md(struct mapped_device *md)
383 {
384 	return test_bit(DMF_DELETING, &md->flags);
385 }
386 
387 static int dm_blk_open(struct block_device *bdev, fmode_t mode)
388 {
389 	struct mapped_device *md;
390 
391 	spin_lock(&_minor_lock);
392 
393 	md = bdev->bd_disk->private_data;
394 	if (!md)
395 		goto out;
396 
397 	if (test_bit(DMF_FREEING, &md->flags) ||
398 	    dm_deleting_md(md)) {
399 		md = NULL;
400 		goto out;
401 	}
402 
403 	dm_get(md);
404 	atomic_inc(&md->open_count);
405 
406 out:
407 	spin_unlock(&_minor_lock);
408 
409 	return md ? 0 : -ENXIO;
410 }
411 
412 static void dm_blk_close(struct gendisk *disk, fmode_t mode)
413 {
414 	struct mapped_device *md = disk->private_data;
415 
416 	spin_lock(&_minor_lock);
417 
418 	if (atomic_dec_and_test(&md->open_count) &&
419 	    (test_bit(DMF_DEFERRED_REMOVE, &md->flags)))
420 		schedule_work(&deferred_remove_work);
421 
422 	dm_put(md);
423 
424 	spin_unlock(&_minor_lock);
425 }
426 
427 int dm_open_count(struct mapped_device *md)
428 {
429 	return atomic_read(&md->open_count);
430 }
431 
432 /*
433  * Guarantees nothing is using the device before it's deleted.
434  */
435 int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred, bool only_deferred)
436 {
437 	int r = 0;
438 
439 	spin_lock(&_minor_lock);
440 
441 	if (dm_open_count(md)) {
442 		r = -EBUSY;
443 		if (mark_deferred)
444 			set_bit(DMF_DEFERRED_REMOVE, &md->flags);
445 	} else if (only_deferred && !test_bit(DMF_DEFERRED_REMOVE, &md->flags))
446 		r = -EEXIST;
447 	else
448 		set_bit(DMF_DELETING, &md->flags);
449 
450 	spin_unlock(&_minor_lock);
451 
452 	return r;
453 }
454 
455 int dm_cancel_deferred_remove(struct mapped_device *md)
456 {
457 	int r = 0;
458 
459 	spin_lock(&_minor_lock);
460 
461 	if (test_bit(DMF_DELETING, &md->flags))
462 		r = -EBUSY;
463 	else
464 		clear_bit(DMF_DEFERRED_REMOVE, &md->flags);
465 
466 	spin_unlock(&_minor_lock);
467 
468 	return r;
469 }
470 
471 static void do_deferred_remove(struct work_struct *w)
472 {
473 	dm_deferred_remove();
474 }
475 
476 sector_t dm_get_size(struct mapped_device *md)
477 {
478 	return get_capacity(md->disk);
479 }
480 
481 struct dm_stats *dm_get_stats(struct mapped_device *md)
482 {
483 	return &md->stats;
484 }
485 
486 static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
487 {
488 	struct mapped_device *md = bdev->bd_disk->private_data;
489 
490 	return dm_get_geometry(md, geo);
491 }
492 
493 static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode,
494 			unsigned int cmd, unsigned long arg)
495 {
496 	struct mapped_device *md = bdev->bd_disk->private_data;
497 	int srcu_idx;
498 	struct dm_table *map;
499 	struct dm_target *tgt;
500 	int r = -ENOTTY;
501 
502 retry:
503 	map = dm_get_live_table(md, &srcu_idx);
504 
505 	if (!map || !dm_table_get_size(map))
506 		goto out;
507 
508 	/* We only support devices that have a single target */
509 	if (dm_table_get_num_targets(map) != 1)
510 		goto out;
511 
512 	tgt = dm_table_get_target(map, 0);
513 
514 	if (dm_suspended_md(md)) {
515 		r = -EAGAIN;
516 		goto out;
517 	}
518 
519 	if (tgt->type->ioctl)
520 		r = tgt->type->ioctl(tgt, cmd, arg);
521 
522 out:
523 	dm_put_live_table(md, srcu_idx);
524 
525 	if (r == -ENOTCONN) {
526 		msleep(10);
527 		goto retry;
528 	}
529 
530 	return r;
531 }
532 
533 static struct dm_io *alloc_io(struct mapped_device *md)
534 {
535 	return mempool_alloc(md->io_pool, GFP_NOIO);
536 }
537 
538 static void free_io(struct mapped_device *md, struct dm_io *io)
539 {
540 	mempool_free(io, md->io_pool);
541 }
542 
543 static void free_tio(struct mapped_device *md, struct dm_target_io *tio)
544 {
545 	bio_put(&tio->clone);
546 }
547 
548 static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md,
549 					    gfp_t gfp_mask)
550 {
551 	return mempool_alloc(md->io_pool, gfp_mask);
552 }
553 
554 static void free_rq_tio(struct dm_rq_target_io *tio)
555 {
556 	mempool_free(tio, tio->md->io_pool);
557 }
558 
559 static int md_in_flight(struct mapped_device *md)
560 {
561 	return atomic_read(&md->pending[READ]) +
562 	       atomic_read(&md->pending[WRITE]);
563 }
564 
565 static void start_io_acct(struct dm_io *io)
566 {
567 	struct mapped_device *md = io->md;
568 	struct bio *bio = io->bio;
569 	int cpu;
570 	int rw = bio_data_dir(bio);
571 
572 	io->start_time = jiffies;
573 
574 	cpu = part_stat_lock();
575 	part_round_stats(cpu, &dm_disk(md)->part0);
576 	part_stat_unlock();
577 	atomic_set(&dm_disk(md)->part0.in_flight[rw],
578 		atomic_inc_return(&md->pending[rw]));
579 
580 	if (unlikely(dm_stats_used(&md->stats)))
581 		dm_stats_account_io(&md->stats, bio->bi_rw, bio->bi_sector,
582 				    bio_sectors(bio), false, 0, &io->stats_aux);
583 }
584 
585 static void end_io_acct(struct dm_io *io)
586 {
587 	struct mapped_device *md = io->md;
588 	struct bio *bio = io->bio;
589 	unsigned long duration = jiffies - io->start_time;
590 	int pending, cpu;
591 	int rw = bio_data_dir(bio);
592 
593 	cpu = part_stat_lock();
594 	part_round_stats(cpu, &dm_disk(md)->part0);
595 	part_stat_add(cpu, &dm_disk(md)->part0, ticks[rw], duration);
596 	part_stat_unlock();
597 
598 	if (unlikely(dm_stats_used(&md->stats)))
599 		dm_stats_account_io(&md->stats, bio->bi_rw, bio->bi_sector,
600 				    bio_sectors(bio), true, duration, &io->stats_aux);
601 
602 	/*
603 	 * After this is decremented the bio must not be touched if it is
604 	 * a flush.
605 	 */
606 	pending = atomic_dec_return(&md->pending[rw]);
607 	atomic_set(&dm_disk(md)->part0.in_flight[rw], pending);
608 	pending += atomic_read(&md->pending[rw^0x1]);
609 
610 	/* nudge anyone waiting on suspend queue */
611 	if (!pending)
612 		wake_up(&md->wait);
613 }
614 
615 /*
616  * Add the bio to the list of deferred io.
617  */
618 static void queue_io(struct mapped_device *md, struct bio *bio)
619 {
620 	unsigned long flags;
621 
622 	spin_lock_irqsave(&md->deferred_lock, flags);
623 	bio_list_add(&md->deferred, bio);
624 	spin_unlock_irqrestore(&md->deferred_lock, flags);
625 	queue_work(md->wq, &md->work);
626 }
627 
628 /*
629  * Everyone (including functions in this file), should use this
630  * function to access the md->map field, and make sure they call
631  * dm_put_live_table() when finished.
632  */
633 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx) __acquires(md->io_barrier)
634 {
635 	*srcu_idx = srcu_read_lock(&md->io_barrier);
636 
637 	return srcu_dereference(md->map, &md->io_barrier);
638 }
639 
640 void dm_put_live_table(struct mapped_device *md, int srcu_idx) __releases(md->io_barrier)
641 {
642 	srcu_read_unlock(&md->io_barrier, srcu_idx);
643 }
644 
645 void dm_sync_table(struct mapped_device *md)
646 {
647 	synchronize_srcu(&md->io_barrier);
648 	synchronize_rcu_expedited();
649 }
650 
651 /*
652  * A fast alternative to dm_get_live_table/dm_put_live_table.
653  * The caller must not block between these two functions.
654  */
655 static struct dm_table *dm_get_live_table_fast(struct mapped_device *md) __acquires(RCU)
656 {
657 	rcu_read_lock();
658 	return rcu_dereference(md->map);
659 }
660 
661 static void dm_put_live_table_fast(struct mapped_device *md) __releases(RCU)
662 {
663 	rcu_read_unlock();
664 }
665 
666 /*
667  * Get the geometry associated with a dm device
668  */
669 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo)
670 {
671 	*geo = md->geometry;
672 
673 	return 0;
674 }
675 
676 /*
677  * Set the geometry of a device.
678  */
679 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo)
680 {
681 	sector_t sz = (sector_t)geo->cylinders * geo->heads * geo->sectors;
682 
683 	if (geo->start > sz) {
684 		DMWARN("Start sector is beyond the geometry limits.");
685 		return -EINVAL;
686 	}
687 
688 	md->geometry = *geo;
689 
690 	return 0;
691 }
692 
693 /*-----------------------------------------------------------------
694  * CRUD START:
695  *   A more elegant soln is in the works that uses the queue
696  *   merge fn, unfortunately there are a couple of changes to
697  *   the block layer that I want to make for this.  So in the
698  *   interests of getting something for people to use I give
699  *   you this clearly demarcated crap.
700  *---------------------------------------------------------------*/
701 
702 static int __noflush_suspending(struct mapped_device *md)
703 {
704 	return test_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
705 }
706 
707 /*
708  * Decrements the number of outstanding ios that a bio has been
709  * cloned into, completing the original io if necc.
710  */
711 static void dec_pending(struct dm_io *io, int error)
712 {
713 	unsigned long flags;
714 	int io_error;
715 	struct bio *bio;
716 	struct mapped_device *md = io->md;
717 
718 	/* Push-back supersedes any I/O errors */
719 	if (unlikely(error)) {
720 		spin_lock_irqsave(&io->endio_lock, flags);
721 		if (!(io->error > 0 && __noflush_suspending(md)))
722 			io->error = error;
723 		spin_unlock_irqrestore(&io->endio_lock, flags);
724 	}
725 
726 	if (atomic_dec_and_test(&io->io_count)) {
727 		if (io->error == DM_ENDIO_REQUEUE) {
728 			/*
729 			 * Target requested pushing back the I/O.
730 			 */
731 			spin_lock_irqsave(&md->deferred_lock, flags);
732 			if (__noflush_suspending(md))
733 				bio_list_add_head(&md->deferred, io->bio);
734 			else
735 				/* noflush suspend was interrupted. */
736 				io->error = -EIO;
737 			spin_unlock_irqrestore(&md->deferred_lock, flags);
738 		}
739 
740 		io_error = io->error;
741 		bio = io->bio;
742 		end_io_acct(io);
743 		free_io(md, io);
744 
745 		if (io_error == DM_ENDIO_REQUEUE)
746 			return;
747 
748 		if ((bio->bi_rw & REQ_FLUSH) && bio->bi_size) {
749 			/*
750 			 * Preflush done for flush with data, reissue
751 			 * without REQ_FLUSH.
752 			 */
753 			bio->bi_rw &= ~REQ_FLUSH;
754 			queue_io(md, bio);
755 		} else {
756 			/* done with normal IO or empty flush */
757 			trace_block_bio_complete(md->queue, bio, io_error);
758 			bio_endio(bio, io_error);
759 		}
760 	}
761 }
762 
763 static void clone_endio(struct bio *bio, int error)
764 {
765 	int r = 0;
766 	struct dm_target_io *tio = bio->bi_private;
767 	struct dm_io *io = tio->io;
768 	struct mapped_device *md = tio->io->md;
769 	dm_endio_fn endio = tio->ti->type->end_io;
770 
771 	if (!bio_flagged(bio, BIO_UPTODATE) && !error)
772 		error = -EIO;
773 
774 	if (endio) {
775 		r = endio(tio->ti, bio, error);
776 		if (r < 0 || r == DM_ENDIO_REQUEUE)
777 			/*
778 			 * error and requeue request are handled
779 			 * in dec_pending().
780 			 */
781 			error = r;
782 		else if (r == DM_ENDIO_INCOMPLETE)
783 			/* The target will handle the io */
784 			return;
785 		else if (r) {
786 			DMWARN("unimplemented target endio return value: %d", r);
787 			BUG();
788 		}
789 	}
790 
791 	free_tio(md, tio);
792 	dec_pending(io, error);
793 }
794 
795 /*
796  * Partial completion handling for request-based dm
797  */
798 static void end_clone_bio(struct bio *clone, int error)
799 {
800 	struct dm_rq_clone_bio_info *info = clone->bi_private;
801 	struct dm_rq_target_io *tio = info->tio;
802 	struct bio *bio = info->orig;
803 	unsigned int nr_bytes = info->orig->bi_size;
804 
805 	bio_put(clone);
806 
807 	if (tio->error)
808 		/*
809 		 * An error has already been detected on the request.
810 		 * Once error occurred, just let clone->end_io() handle
811 		 * the remainder.
812 		 */
813 		return;
814 	else if (error) {
815 		/*
816 		 * Don't notice the error to the upper layer yet.
817 		 * The error handling decision is made by the target driver,
818 		 * when the request is completed.
819 		 */
820 		tio->error = error;
821 		return;
822 	}
823 
824 	/*
825 	 * I/O for the bio successfully completed.
826 	 * Notice the data completion to the upper layer.
827 	 */
828 
829 	/*
830 	 * bios are processed from the head of the list.
831 	 * So the completing bio should always be rq->bio.
832 	 * If it's not, something wrong is happening.
833 	 */
834 	if (tio->orig->bio != bio)
835 		DMERR("bio completion is going in the middle of the request");
836 
837 	/*
838 	 * Update the original request.
839 	 * Do not use blk_end_request() here, because it may complete
840 	 * the original request before the clone, and break the ordering.
841 	 */
842 	blk_update_request(tio->orig, 0, nr_bytes);
843 }
844 
845 /*
846  * Don't touch any member of the md after calling this function because
847  * the md may be freed in dm_put() at the end of this function.
848  * Or do dm_get() before calling this function and dm_put() later.
849  */
850 static void rq_completed(struct mapped_device *md, int rw, int run_queue)
851 {
852 	atomic_dec(&md->pending[rw]);
853 
854 	/* nudge anyone waiting on suspend queue */
855 	if (!md_in_flight(md))
856 		wake_up(&md->wait);
857 
858 	/*
859 	 * Run this off this callpath, as drivers could invoke end_io while
860 	 * inside their request_fn (and holding the queue lock). Calling
861 	 * back into ->request_fn() could deadlock attempting to grab the
862 	 * queue lock again.
863 	 */
864 	if (run_queue)
865 		blk_run_queue_async(md->queue);
866 
867 	/*
868 	 * dm_put() must be at the end of this function. See the comment above
869 	 */
870 	dm_put(md);
871 }
872 
873 static void free_rq_clone(struct request *clone)
874 {
875 	struct dm_rq_target_io *tio = clone->end_io_data;
876 
877 	blk_rq_unprep_clone(clone);
878 	free_rq_tio(tio);
879 }
880 
881 /*
882  * Complete the clone and the original request.
883  * Must be called without queue lock.
884  */
885 static void dm_end_request(struct request *clone, int error)
886 {
887 	int rw = rq_data_dir(clone);
888 	struct dm_rq_target_io *tio = clone->end_io_data;
889 	struct mapped_device *md = tio->md;
890 	struct request *rq = tio->orig;
891 
892 	if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
893 		rq->errors = clone->errors;
894 		rq->resid_len = clone->resid_len;
895 
896 		if (rq->sense)
897 			/*
898 			 * We are using the sense buffer of the original
899 			 * request.
900 			 * So setting the length of the sense data is enough.
901 			 */
902 			rq->sense_len = clone->sense_len;
903 	}
904 
905 	free_rq_clone(clone);
906 	blk_end_request_all(rq, error);
907 	rq_completed(md, rw, true);
908 }
909 
910 static void dm_unprep_request(struct request *rq)
911 {
912 	struct request *clone = rq->special;
913 
914 	rq->special = NULL;
915 	rq->cmd_flags &= ~REQ_DONTPREP;
916 
917 	free_rq_clone(clone);
918 }
919 
920 /*
921  * Requeue the original request of a clone.
922  */
923 void dm_requeue_unmapped_request(struct request *clone)
924 {
925 	int rw = rq_data_dir(clone);
926 	struct dm_rq_target_io *tio = clone->end_io_data;
927 	struct mapped_device *md = tio->md;
928 	struct request *rq = tio->orig;
929 	struct request_queue *q = rq->q;
930 	unsigned long flags;
931 
932 	dm_unprep_request(rq);
933 
934 	spin_lock_irqsave(q->queue_lock, flags);
935 	blk_requeue_request(q, rq);
936 	spin_unlock_irqrestore(q->queue_lock, flags);
937 
938 	rq_completed(md, rw, 0);
939 }
940 EXPORT_SYMBOL_GPL(dm_requeue_unmapped_request);
941 
942 static void __stop_queue(struct request_queue *q)
943 {
944 	blk_stop_queue(q);
945 }
946 
947 static void stop_queue(struct request_queue *q)
948 {
949 	unsigned long flags;
950 
951 	spin_lock_irqsave(q->queue_lock, flags);
952 	__stop_queue(q);
953 	spin_unlock_irqrestore(q->queue_lock, flags);
954 }
955 
956 static void __start_queue(struct request_queue *q)
957 {
958 	if (blk_queue_stopped(q))
959 		blk_start_queue(q);
960 }
961 
962 static void start_queue(struct request_queue *q)
963 {
964 	unsigned long flags;
965 
966 	spin_lock_irqsave(q->queue_lock, flags);
967 	__start_queue(q);
968 	spin_unlock_irqrestore(q->queue_lock, flags);
969 }
970 
971 static void dm_done(struct request *clone, int error, bool mapped)
972 {
973 	int r = error;
974 	struct dm_rq_target_io *tio = clone->end_io_data;
975 	dm_request_endio_fn rq_end_io = NULL;
976 
977 	if (tio->ti) {
978 		rq_end_io = tio->ti->type->rq_end_io;
979 
980 		if (mapped && rq_end_io)
981 			r = rq_end_io(tio->ti, clone, error, &tio->info);
982 	}
983 
984 	if (r <= 0)
985 		/* The target wants to complete the I/O */
986 		dm_end_request(clone, r);
987 	else if (r == DM_ENDIO_INCOMPLETE)
988 		/* The target will handle the I/O */
989 		return;
990 	else if (r == DM_ENDIO_REQUEUE)
991 		/* The target wants to requeue the I/O */
992 		dm_requeue_unmapped_request(clone);
993 	else {
994 		DMWARN("unimplemented target endio return value: %d", r);
995 		BUG();
996 	}
997 }
998 
999 /*
1000  * Request completion handler for request-based dm
1001  */
1002 static void dm_softirq_done(struct request *rq)
1003 {
1004 	bool mapped = true;
1005 	struct request *clone = rq->completion_data;
1006 	struct dm_rq_target_io *tio = clone->end_io_data;
1007 
1008 	if (rq->cmd_flags & REQ_FAILED)
1009 		mapped = false;
1010 
1011 	dm_done(clone, tio->error, mapped);
1012 }
1013 
1014 /*
1015  * Complete the clone and the original request with the error status
1016  * through softirq context.
1017  */
1018 static void dm_complete_request(struct request *clone, int error)
1019 {
1020 	struct dm_rq_target_io *tio = clone->end_io_data;
1021 	struct request *rq = tio->orig;
1022 
1023 	tio->error = error;
1024 	rq->completion_data = clone;
1025 	blk_complete_request(rq);
1026 }
1027 
1028 /*
1029  * Complete the not-mapped clone and the original request with the error status
1030  * through softirq context.
1031  * Target's rq_end_io() function isn't called.
1032  * This may be used when the target's map_rq() function fails.
1033  */
1034 void dm_kill_unmapped_request(struct request *clone, int error)
1035 {
1036 	struct dm_rq_target_io *tio = clone->end_io_data;
1037 	struct request *rq = tio->orig;
1038 
1039 	rq->cmd_flags |= REQ_FAILED;
1040 	dm_complete_request(clone, error);
1041 }
1042 EXPORT_SYMBOL_GPL(dm_kill_unmapped_request);
1043 
1044 /*
1045  * Called with the queue lock held
1046  */
1047 static void end_clone_request(struct request *clone, int error)
1048 {
1049 	/*
1050 	 * For just cleaning up the information of the queue in which
1051 	 * the clone was dispatched.
1052 	 * The clone is *NOT* freed actually here because it is alloced from
1053 	 * dm own mempool and REQ_ALLOCED isn't set in clone->cmd_flags.
1054 	 */
1055 	__blk_put_request(clone->q, clone);
1056 
1057 	/*
1058 	 * Actual request completion is done in a softirq context which doesn't
1059 	 * hold the queue lock.  Otherwise, deadlock could occur because:
1060 	 *     - another request may be submitted by the upper level driver
1061 	 *       of the stacking during the completion
1062 	 *     - the submission which requires queue lock may be done
1063 	 *       against this queue
1064 	 */
1065 	dm_complete_request(clone, error);
1066 }
1067 
1068 /*
1069  * Return maximum size of I/O possible at the supplied sector up to the current
1070  * target boundary.
1071  */
1072 static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti)
1073 {
1074 	sector_t target_offset = dm_target_offset(ti, sector);
1075 
1076 	return ti->len - target_offset;
1077 }
1078 
1079 static sector_t max_io_len(sector_t sector, struct dm_target *ti)
1080 {
1081 	sector_t len = max_io_len_target_boundary(sector, ti);
1082 	sector_t offset, max_len;
1083 
1084 	/*
1085 	 * Does the target need to split even further?
1086 	 */
1087 	if (ti->max_io_len) {
1088 		offset = dm_target_offset(ti, sector);
1089 		if (unlikely(ti->max_io_len & (ti->max_io_len - 1)))
1090 			max_len = sector_div(offset, ti->max_io_len);
1091 		else
1092 			max_len = offset & (ti->max_io_len - 1);
1093 		max_len = ti->max_io_len - max_len;
1094 
1095 		if (len > max_len)
1096 			len = max_len;
1097 	}
1098 
1099 	return len;
1100 }
1101 
1102 int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
1103 {
1104 	if (len > UINT_MAX) {
1105 		DMERR("Specified maximum size of target IO (%llu) exceeds limit (%u)",
1106 		      (unsigned long long)len, UINT_MAX);
1107 		ti->error = "Maximum size of target IO is too large";
1108 		return -EINVAL;
1109 	}
1110 
1111 	ti->max_io_len = (uint32_t) len;
1112 
1113 	return 0;
1114 }
1115 EXPORT_SYMBOL_GPL(dm_set_target_max_io_len);
1116 
1117 static void __map_bio(struct dm_target_io *tio)
1118 {
1119 	int r;
1120 	sector_t sector;
1121 	struct mapped_device *md;
1122 	struct bio *clone = &tio->clone;
1123 	struct dm_target *ti = tio->ti;
1124 
1125 	clone->bi_end_io = clone_endio;
1126 	clone->bi_private = tio;
1127 
1128 	/*
1129 	 * Map the clone.  If r == 0 we don't need to do
1130 	 * anything, the target has assumed ownership of
1131 	 * this io.
1132 	 */
1133 	atomic_inc(&tio->io->io_count);
1134 	sector = clone->bi_sector;
1135 	r = ti->type->map(ti, clone);
1136 	if (r == DM_MAPIO_REMAPPED) {
1137 		/* the bio has been remapped so dispatch it */
1138 
1139 		trace_block_bio_remap(bdev_get_queue(clone->bi_bdev), clone,
1140 				      tio->io->bio->bi_bdev->bd_dev, sector);
1141 
1142 		generic_make_request(clone);
1143 	} else if (r < 0 || r == DM_MAPIO_REQUEUE) {
1144 		/* error the io and bail out, or requeue it if needed */
1145 		md = tio->io->md;
1146 		dec_pending(tio->io, r);
1147 		free_tio(md, tio);
1148 	} else if (r) {
1149 		DMWARN("unimplemented target map return value: %d", r);
1150 		BUG();
1151 	}
1152 }
1153 
1154 struct clone_info {
1155 	struct mapped_device *md;
1156 	struct dm_table *map;
1157 	struct bio *bio;
1158 	struct dm_io *io;
1159 	sector_t sector;
1160 	sector_t sector_count;
1161 	unsigned short idx;
1162 };
1163 
1164 static void bio_setup_sector(struct bio *bio, sector_t sector, sector_t len)
1165 {
1166 	bio->bi_sector = sector;
1167 	bio->bi_size = to_bytes(len);
1168 }
1169 
1170 static void bio_setup_bv(struct bio *bio, unsigned short idx, unsigned short bv_count)
1171 {
1172 	bio->bi_idx = idx;
1173 	bio->bi_vcnt = idx + bv_count;
1174 	bio->bi_flags &= ~(1 << BIO_SEG_VALID);
1175 }
1176 
1177 static void clone_bio_integrity(struct bio *bio, struct bio *clone,
1178 				unsigned short idx, unsigned len, unsigned offset,
1179 				unsigned trim)
1180 {
1181 	if (!bio_integrity(bio))
1182 		return;
1183 
1184 	bio_integrity_clone(clone, bio, GFP_NOIO);
1185 
1186 	if (trim)
1187 		bio_integrity_trim(clone, bio_sector_offset(bio, idx, offset), len);
1188 }
1189 
1190 /*
1191  * Creates a little bio that just does part of a bvec.
1192  */
1193 static void clone_split_bio(struct dm_target_io *tio, struct bio *bio,
1194 			    sector_t sector, unsigned short idx,
1195 			    unsigned offset, unsigned len)
1196 {
1197 	struct bio *clone = &tio->clone;
1198 	struct bio_vec *bv = bio->bi_io_vec + idx;
1199 
1200 	*clone->bi_io_vec = *bv;
1201 
1202 	bio_setup_sector(clone, sector, len);
1203 
1204 	clone->bi_bdev = bio->bi_bdev;
1205 	clone->bi_rw = bio->bi_rw;
1206 	clone->bi_vcnt = 1;
1207 	clone->bi_io_vec->bv_offset = offset;
1208 	clone->bi_io_vec->bv_len = clone->bi_size;
1209 	clone->bi_flags |= 1 << BIO_CLONED;
1210 
1211 	clone_bio_integrity(bio, clone, idx, len, offset, 1);
1212 }
1213 
1214 /*
1215  * Creates a bio that consists of range of complete bvecs.
1216  */
1217 static void clone_bio(struct dm_target_io *tio, struct bio *bio,
1218 		      sector_t sector, unsigned short idx,
1219 		      unsigned short bv_count, unsigned len)
1220 {
1221 	struct bio *clone = &tio->clone;
1222 	unsigned trim = 0;
1223 
1224 	__bio_clone(clone, bio);
1225 	bio_setup_sector(clone, sector, len);
1226 	bio_setup_bv(clone, idx, bv_count);
1227 
1228 	if (idx != bio->bi_idx || clone->bi_size < bio->bi_size)
1229 		trim = 1;
1230 	clone_bio_integrity(bio, clone, idx, len, 0, trim);
1231 }
1232 
1233 static struct dm_target_io *alloc_tio(struct clone_info *ci,
1234 				      struct dm_target *ti, int nr_iovecs,
1235 				      unsigned target_bio_nr)
1236 {
1237 	struct dm_target_io *tio;
1238 	struct bio *clone;
1239 
1240 	clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, ci->md->bs);
1241 	tio = container_of(clone, struct dm_target_io, clone);
1242 
1243 	tio->io = ci->io;
1244 	tio->ti = ti;
1245 	memset(&tio->info, 0, sizeof(tio->info));
1246 	tio->target_bio_nr = target_bio_nr;
1247 
1248 	return tio;
1249 }
1250 
1251 static void __clone_and_map_simple_bio(struct clone_info *ci,
1252 				       struct dm_target *ti,
1253 				       unsigned target_bio_nr, sector_t len)
1254 {
1255 	struct dm_target_io *tio = alloc_tio(ci, ti, ci->bio->bi_max_vecs, target_bio_nr);
1256 	struct bio *clone = &tio->clone;
1257 
1258 	/*
1259 	 * Discard requests require the bio's inline iovecs be initialized.
1260 	 * ci->bio->bi_max_vecs is BIO_INLINE_VECS anyway, for both flush
1261 	 * and discard, so no need for concern about wasted bvec allocations.
1262 	 */
1263 	 __bio_clone(clone, ci->bio);
1264 	if (len)
1265 		bio_setup_sector(clone, ci->sector, len);
1266 
1267 	__map_bio(tio);
1268 }
1269 
1270 static void __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti,
1271 				  unsigned num_bios, sector_t len)
1272 {
1273 	unsigned target_bio_nr;
1274 
1275 	for (target_bio_nr = 0; target_bio_nr < num_bios; target_bio_nr++)
1276 		__clone_and_map_simple_bio(ci, ti, target_bio_nr, len);
1277 }
1278 
1279 static int __send_empty_flush(struct clone_info *ci)
1280 {
1281 	unsigned target_nr = 0;
1282 	struct dm_target *ti;
1283 
1284 	BUG_ON(bio_has_data(ci->bio));
1285 	while ((ti = dm_table_get_target(ci->map, target_nr++)))
1286 		__send_duplicate_bios(ci, ti, ti->num_flush_bios, 0);
1287 
1288 	return 0;
1289 }
1290 
1291 static void __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti,
1292 				     sector_t sector, int nr_iovecs,
1293 				     unsigned short idx, unsigned short bv_count,
1294 				     unsigned offset, unsigned len,
1295 				     unsigned split_bvec)
1296 {
1297 	struct bio *bio = ci->bio;
1298 	struct dm_target_io *tio;
1299 	unsigned target_bio_nr;
1300 	unsigned num_target_bios = 1;
1301 
1302 	/*
1303 	 * Does the target want to receive duplicate copies of the bio?
1304 	 */
1305 	if (bio_data_dir(bio) == WRITE && ti->num_write_bios)
1306 		num_target_bios = ti->num_write_bios(ti, bio);
1307 
1308 	for (target_bio_nr = 0; target_bio_nr < num_target_bios; target_bio_nr++) {
1309 		tio = alloc_tio(ci, ti, nr_iovecs, target_bio_nr);
1310 		if (split_bvec)
1311 			clone_split_bio(tio, bio, sector, idx, offset, len);
1312 		else
1313 			clone_bio(tio, bio, sector, idx, bv_count, len);
1314 		__map_bio(tio);
1315 	}
1316 }
1317 
1318 typedef unsigned (*get_num_bios_fn)(struct dm_target *ti);
1319 
1320 static unsigned get_num_discard_bios(struct dm_target *ti)
1321 {
1322 	return ti->num_discard_bios;
1323 }
1324 
1325 static unsigned get_num_write_same_bios(struct dm_target *ti)
1326 {
1327 	return ti->num_write_same_bios;
1328 }
1329 
1330 typedef bool (*is_split_required_fn)(struct dm_target *ti);
1331 
1332 static bool is_split_required_for_discard(struct dm_target *ti)
1333 {
1334 	return ti->split_discard_bios;
1335 }
1336 
1337 static int __send_changing_extent_only(struct clone_info *ci,
1338 				       get_num_bios_fn get_num_bios,
1339 				       is_split_required_fn is_split_required)
1340 {
1341 	struct dm_target *ti;
1342 	sector_t len;
1343 	unsigned num_bios;
1344 
1345 	do {
1346 		ti = dm_table_find_target(ci->map, ci->sector);
1347 		if (!dm_target_is_valid(ti))
1348 			return -EIO;
1349 
1350 		/*
1351 		 * Even though the device advertised support for this type of
1352 		 * request, that does not mean every target supports it, and
1353 		 * reconfiguration might also have changed that since the
1354 		 * check was performed.
1355 		 */
1356 		num_bios = get_num_bios ? get_num_bios(ti) : 0;
1357 		if (!num_bios)
1358 			return -EOPNOTSUPP;
1359 
1360 		if (is_split_required && !is_split_required(ti))
1361 			len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
1362 		else
1363 			len = min(ci->sector_count, max_io_len(ci->sector, ti));
1364 
1365 		__send_duplicate_bios(ci, ti, num_bios, len);
1366 
1367 		ci->sector += len;
1368 	} while (ci->sector_count -= len);
1369 
1370 	return 0;
1371 }
1372 
1373 static int __send_discard(struct clone_info *ci)
1374 {
1375 	return __send_changing_extent_only(ci, get_num_discard_bios,
1376 					   is_split_required_for_discard);
1377 }
1378 
1379 static int __send_write_same(struct clone_info *ci)
1380 {
1381 	return __send_changing_extent_only(ci, get_num_write_same_bios, NULL);
1382 }
1383 
1384 /*
1385  * Find maximum number of sectors / bvecs we can process with a single bio.
1386  */
1387 static sector_t __len_within_target(struct clone_info *ci, sector_t max, int *idx)
1388 {
1389 	struct bio *bio = ci->bio;
1390 	sector_t bv_len, total_len = 0;
1391 
1392 	for (*idx = ci->idx; max && (*idx < bio->bi_vcnt); (*idx)++) {
1393 		bv_len = to_sector(bio->bi_io_vec[*idx].bv_len);
1394 
1395 		if (bv_len > max)
1396 			break;
1397 
1398 		max -= bv_len;
1399 		total_len += bv_len;
1400 	}
1401 
1402 	return total_len;
1403 }
1404 
1405 static int __split_bvec_across_targets(struct clone_info *ci,
1406 				       struct dm_target *ti, sector_t max)
1407 {
1408 	struct bio *bio = ci->bio;
1409 	struct bio_vec *bv = bio->bi_io_vec + ci->idx;
1410 	sector_t remaining = to_sector(bv->bv_len);
1411 	unsigned offset = 0;
1412 	sector_t len;
1413 
1414 	do {
1415 		if (offset) {
1416 			ti = dm_table_find_target(ci->map, ci->sector);
1417 			if (!dm_target_is_valid(ti))
1418 				return -EIO;
1419 
1420 			max = max_io_len(ci->sector, ti);
1421 		}
1422 
1423 		len = min(remaining, max);
1424 
1425 		__clone_and_map_data_bio(ci, ti, ci->sector, 1, ci->idx, 0,
1426 					 bv->bv_offset + offset, len, 1);
1427 
1428 		ci->sector += len;
1429 		ci->sector_count -= len;
1430 		offset += to_bytes(len);
1431 	} while (remaining -= len);
1432 
1433 	ci->idx++;
1434 
1435 	return 0;
1436 }
1437 
1438 /*
1439  * Select the correct strategy for processing a non-flush bio.
1440  */
1441 static int __split_and_process_non_flush(struct clone_info *ci)
1442 {
1443 	struct bio *bio = ci->bio;
1444 	struct dm_target *ti;
1445 	sector_t len, max;
1446 	int idx;
1447 
1448 	if (unlikely(bio->bi_rw & REQ_DISCARD))
1449 		return __send_discard(ci);
1450 	else if (unlikely(bio->bi_rw & REQ_WRITE_SAME))
1451 		return __send_write_same(ci);
1452 
1453 	ti = dm_table_find_target(ci->map, ci->sector);
1454 	if (!dm_target_is_valid(ti))
1455 		return -EIO;
1456 
1457 	max = max_io_len(ci->sector, ti);
1458 
1459 	/*
1460 	 * Optimise for the simple case where we can do all of
1461 	 * the remaining io with a single clone.
1462 	 */
1463 	if (ci->sector_count <= max) {
1464 		__clone_and_map_data_bio(ci, ti, ci->sector, bio->bi_max_vecs,
1465 					 ci->idx, bio->bi_vcnt - ci->idx, 0,
1466 					 ci->sector_count, 0);
1467 		ci->sector_count = 0;
1468 		return 0;
1469 	}
1470 
1471 	/*
1472 	 * There are some bvecs that don't span targets.
1473 	 * Do as many of these as possible.
1474 	 */
1475 	if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) {
1476 		len = __len_within_target(ci, max, &idx);
1477 
1478 		__clone_and_map_data_bio(ci, ti, ci->sector, bio->bi_max_vecs,
1479 					 ci->idx, idx - ci->idx, 0, len, 0);
1480 
1481 		ci->sector += len;
1482 		ci->sector_count -= len;
1483 		ci->idx = idx;
1484 
1485 		return 0;
1486 	}
1487 
1488 	/*
1489 	 * Handle a bvec that must be split between two or more targets.
1490 	 */
1491 	return __split_bvec_across_targets(ci, ti, max);
1492 }
1493 
1494 /*
1495  * Entry point to split a bio into clones and submit them to the targets.
1496  */
1497 static void __split_and_process_bio(struct mapped_device *md,
1498 				    struct dm_table *map, struct bio *bio)
1499 {
1500 	struct clone_info ci;
1501 	int error = 0;
1502 
1503 	if (unlikely(!map)) {
1504 		bio_io_error(bio);
1505 		return;
1506 	}
1507 
1508 	ci.map = map;
1509 	ci.md = md;
1510 	ci.io = alloc_io(md);
1511 	ci.io->error = 0;
1512 	atomic_set(&ci.io->io_count, 1);
1513 	ci.io->bio = bio;
1514 	ci.io->md = md;
1515 	spin_lock_init(&ci.io->endio_lock);
1516 	ci.sector = bio->bi_sector;
1517 	ci.idx = bio->bi_idx;
1518 
1519 	start_io_acct(ci.io);
1520 
1521 	if (bio->bi_rw & REQ_FLUSH) {
1522 		ci.bio = &ci.md->flush_bio;
1523 		ci.sector_count = 0;
1524 		error = __send_empty_flush(&ci);
1525 		/* dec_pending submits any data associated with flush */
1526 	} else {
1527 		ci.bio = bio;
1528 		ci.sector_count = bio_sectors(bio);
1529 		while (ci.sector_count && !error)
1530 			error = __split_and_process_non_flush(&ci);
1531 	}
1532 
1533 	/* drop the extra reference count */
1534 	dec_pending(ci.io, error);
1535 }
1536 /*-----------------------------------------------------------------
1537  * CRUD END
1538  *---------------------------------------------------------------*/
1539 
1540 static int dm_merge_bvec(struct request_queue *q,
1541 			 struct bvec_merge_data *bvm,
1542 			 struct bio_vec *biovec)
1543 {
1544 	struct mapped_device *md = q->queuedata;
1545 	struct dm_table *map = dm_get_live_table_fast(md);
1546 	struct dm_target *ti;
1547 	sector_t max_sectors;
1548 	int max_size = 0;
1549 
1550 	if (unlikely(!map))
1551 		goto out;
1552 
1553 	ti = dm_table_find_target(map, bvm->bi_sector);
1554 	if (!dm_target_is_valid(ti))
1555 		goto out;
1556 
1557 	/*
1558 	 * Find maximum amount of I/O that won't need splitting
1559 	 */
1560 	max_sectors = min(max_io_len(bvm->bi_sector, ti),
1561 			  (sector_t) BIO_MAX_SECTORS);
1562 	max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
1563 	if (max_size < 0)
1564 		max_size = 0;
1565 
1566 	/*
1567 	 * merge_bvec_fn() returns number of bytes
1568 	 * it can accept at this offset
1569 	 * max is precomputed maximal io size
1570 	 */
1571 	if (max_size && ti->type->merge)
1572 		max_size = ti->type->merge(ti, bvm, biovec, max_size);
1573 	/*
1574 	 * If the target doesn't support merge method and some of the devices
1575 	 * provided their merge_bvec method (we know this by looking at
1576 	 * queue_max_hw_sectors), then we can't allow bios with multiple vector
1577 	 * entries.  So always set max_size to 0, and the code below allows
1578 	 * just one page.
1579 	 */
1580 	else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9)
1581 
1582 		max_size = 0;
1583 
1584 out:
1585 	dm_put_live_table_fast(md);
1586 	/*
1587 	 * Always allow an entire first page
1588 	 */
1589 	if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT))
1590 		max_size = biovec->bv_len;
1591 
1592 	return max_size;
1593 }
1594 
1595 /*
1596  * The request function that just remaps the bio built up by
1597  * dm_merge_bvec.
1598  */
1599 static void _dm_request(struct request_queue *q, struct bio *bio)
1600 {
1601 	int rw = bio_data_dir(bio);
1602 	struct mapped_device *md = q->queuedata;
1603 	int cpu;
1604 	int srcu_idx;
1605 	struct dm_table *map;
1606 
1607 	map = dm_get_live_table(md, &srcu_idx);
1608 
1609 	cpu = part_stat_lock();
1610 	part_stat_inc(cpu, &dm_disk(md)->part0, ios[rw]);
1611 	part_stat_add(cpu, &dm_disk(md)->part0, sectors[rw], bio_sectors(bio));
1612 	part_stat_unlock();
1613 
1614 	/* if we're suspended, we have to queue this io for later */
1615 	if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) {
1616 		dm_put_live_table(md, srcu_idx);
1617 
1618 		if (bio_rw(bio) != READA)
1619 			queue_io(md, bio);
1620 		else
1621 			bio_io_error(bio);
1622 		return;
1623 	}
1624 
1625 	__split_and_process_bio(md, map, bio);
1626 	dm_put_live_table(md, srcu_idx);
1627 	return;
1628 }
1629 
1630 int dm_request_based(struct mapped_device *md)
1631 {
1632 	return blk_queue_stackable(md->queue);
1633 }
1634 
1635 static void dm_request(struct request_queue *q, struct bio *bio)
1636 {
1637 	struct mapped_device *md = q->queuedata;
1638 
1639 	if (dm_request_based(md))
1640 		blk_queue_bio(q, bio);
1641 	else
1642 		_dm_request(q, bio);
1643 }
1644 
1645 void dm_dispatch_request(struct request *rq)
1646 {
1647 	int r;
1648 
1649 	if (blk_queue_io_stat(rq->q))
1650 		rq->cmd_flags |= REQ_IO_STAT;
1651 
1652 	rq->start_time = jiffies;
1653 	r = blk_insert_cloned_request(rq->q, rq);
1654 	if (r)
1655 		dm_complete_request(rq, r);
1656 }
1657 EXPORT_SYMBOL_GPL(dm_dispatch_request);
1658 
1659 static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
1660 				 void *data)
1661 {
1662 	struct dm_rq_target_io *tio = data;
1663 	struct dm_rq_clone_bio_info *info =
1664 		container_of(bio, struct dm_rq_clone_bio_info, clone);
1665 
1666 	info->orig = bio_orig;
1667 	info->tio = tio;
1668 	bio->bi_end_io = end_clone_bio;
1669 	bio->bi_private = info;
1670 
1671 	return 0;
1672 }
1673 
1674 static int setup_clone(struct request *clone, struct request *rq,
1675 		       struct dm_rq_target_io *tio)
1676 {
1677 	int r;
1678 
1679 	r = blk_rq_prep_clone(clone, rq, tio->md->bs, GFP_ATOMIC,
1680 			      dm_rq_bio_constructor, tio);
1681 	if (r)
1682 		return r;
1683 
1684 	clone->cmd = rq->cmd;
1685 	clone->cmd_len = rq->cmd_len;
1686 	clone->sense = rq->sense;
1687 	clone->buffer = rq->buffer;
1688 	clone->end_io = end_clone_request;
1689 	clone->end_io_data = tio;
1690 
1691 	return 0;
1692 }
1693 
1694 static struct request *clone_rq(struct request *rq, struct mapped_device *md,
1695 				gfp_t gfp_mask)
1696 {
1697 	struct request *clone;
1698 	struct dm_rq_target_io *tio;
1699 
1700 	tio = alloc_rq_tio(md, gfp_mask);
1701 	if (!tio)
1702 		return NULL;
1703 
1704 	tio->md = md;
1705 	tio->ti = NULL;
1706 	tio->orig = rq;
1707 	tio->error = 0;
1708 	memset(&tio->info, 0, sizeof(tio->info));
1709 
1710 	clone = &tio->clone;
1711 	if (setup_clone(clone, rq, tio)) {
1712 		/* -ENOMEM */
1713 		free_rq_tio(tio);
1714 		return NULL;
1715 	}
1716 
1717 	return clone;
1718 }
1719 
1720 /*
1721  * Called with the queue lock held.
1722  */
1723 static int dm_prep_fn(struct request_queue *q, struct request *rq)
1724 {
1725 	struct mapped_device *md = q->queuedata;
1726 	struct request *clone;
1727 
1728 	if (unlikely(rq->special)) {
1729 		DMWARN("Already has something in rq->special.");
1730 		return BLKPREP_KILL;
1731 	}
1732 
1733 	clone = clone_rq(rq, md, GFP_ATOMIC);
1734 	if (!clone)
1735 		return BLKPREP_DEFER;
1736 
1737 	rq->special = clone;
1738 	rq->cmd_flags |= REQ_DONTPREP;
1739 
1740 	return BLKPREP_OK;
1741 }
1742 
1743 /*
1744  * Returns:
1745  * 0  : the request has been processed (not requeued)
1746  * !0 : the request has been requeued
1747  */
1748 static int map_request(struct dm_target *ti, struct request *clone,
1749 		       struct mapped_device *md)
1750 {
1751 	int r, requeued = 0;
1752 	struct dm_rq_target_io *tio = clone->end_io_data;
1753 
1754 	tio->ti = ti;
1755 	r = ti->type->map_rq(ti, clone, &tio->info);
1756 	switch (r) {
1757 	case DM_MAPIO_SUBMITTED:
1758 		/* The target has taken the I/O to submit by itself later */
1759 		break;
1760 	case DM_MAPIO_REMAPPED:
1761 		/* The target has remapped the I/O so dispatch it */
1762 		trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
1763 				     blk_rq_pos(tio->orig));
1764 		dm_dispatch_request(clone);
1765 		break;
1766 	case DM_MAPIO_REQUEUE:
1767 		/* The target wants to requeue the I/O */
1768 		dm_requeue_unmapped_request(clone);
1769 		requeued = 1;
1770 		break;
1771 	default:
1772 		if (r > 0) {
1773 			DMWARN("unimplemented target map return value: %d", r);
1774 			BUG();
1775 		}
1776 
1777 		/* The target wants to complete the I/O */
1778 		dm_kill_unmapped_request(clone, r);
1779 		break;
1780 	}
1781 
1782 	return requeued;
1783 }
1784 
1785 static struct request *dm_start_request(struct mapped_device *md, struct request *orig)
1786 {
1787 	struct request *clone;
1788 
1789 	blk_start_request(orig);
1790 	clone = orig->special;
1791 	atomic_inc(&md->pending[rq_data_dir(clone)]);
1792 
1793 	/*
1794 	 * Hold the md reference here for the in-flight I/O.
1795 	 * We can't rely on the reference count by device opener,
1796 	 * because the device may be closed during the request completion
1797 	 * when all bios are completed.
1798 	 * See the comment in rq_completed() too.
1799 	 */
1800 	dm_get(md);
1801 
1802 	return clone;
1803 }
1804 
1805 /*
1806  * q->request_fn for request-based dm.
1807  * Called with the queue lock held.
1808  */
1809 static void dm_request_fn(struct request_queue *q)
1810 {
1811 	struct mapped_device *md = q->queuedata;
1812 	int srcu_idx;
1813 	struct dm_table *map = dm_get_live_table(md, &srcu_idx);
1814 	struct dm_target *ti;
1815 	struct request *rq, *clone;
1816 	sector_t pos;
1817 
1818 	/*
1819 	 * For suspend, check blk_queue_stopped() and increment
1820 	 * ->pending within a single queue_lock not to increment the
1821 	 * number of in-flight I/Os after the queue is stopped in
1822 	 * dm_suspend().
1823 	 */
1824 	while (!blk_queue_stopped(q)) {
1825 		rq = blk_peek_request(q);
1826 		if (!rq)
1827 			goto delay_and_out;
1828 
1829 		/* always use block 0 to find the target for flushes for now */
1830 		pos = 0;
1831 		if (!(rq->cmd_flags & REQ_FLUSH))
1832 			pos = blk_rq_pos(rq);
1833 
1834 		ti = dm_table_find_target(map, pos);
1835 		if (!dm_target_is_valid(ti)) {
1836 			/*
1837 			 * Must perform setup, that dm_done() requires,
1838 			 * before calling dm_kill_unmapped_request
1839 			 */
1840 			DMERR_LIMIT("request attempted access beyond the end of device");
1841 			clone = dm_start_request(md, rq);
1842 			dm_kill_unmapped_request(clone, -EIO);
1843 			continue;
1844 		}
1845 
1846 		if (ti->type->busy && ti->type->busy(ti))
1847 			goto delay_and_out;
1848 
1849 		clone = dm_start_request(md, rq);
1850 
1851 		spin_unlock(q->queue_lock);
1852 		if (map_request(ti, clone, md))
1853 			goto requeued;
1854 
1855 		BUG_ON(!irqs_disabled());
1856 		spin_lock(q->queue_lock);
1857 	}
1858 
1859 	goto out;
1860 
1861 requeued:
1862 	BUG_ON(!irqs_disabled());
1863 	spin_lock(q->queue_lock);
1864 
1865 delay_and_out:
1866 	blk_delay_queue(q, HZ / 10);
1867 out:
1868 	dm_put_live_table(md, srcu_idx);
1869 }
1870 
1871 int dm_underlying_device_busy(struct request_queue *q)
1872 {
1873 	return blk_lld_busy(q);
1874 }
1875 EXPORT_SYMBOL_GPL(dm_underlying_device_busy);
1876 
1877 static int dm_lld_busy(struct request_queue *q)
1878 {
1879 	int r;
1880 	struct mapped_device *md = q->queuedata;
1881 	struct dm_table *map = dm_get_live_table_fast(md);
1882 
1883 	if (!map || test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))
1884 		r = 1;
1885 	else
1886 		r = dm_table_any_busy_target(map);
1887 
1888 	dm_put_live_table_fast(md);
1889 
1890 	return r;
1891 }
1892 
1893 static int dm_any_congested(void *congested_data, int bdi_bits)
1894 {
1895 	int r = bdi_bits;
1896 	struct mapped_device *md = congested_data;
1897 	struct dm_table *map;
1898 
1899 	if (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
1900 		map = dm_get_live_table_fast(md);
1901 		if (map) {
1902 			/*
1903 			 * Request-based dm cares about only own queue for
1904 			 * the query about congestion status of request_queue
1905 			 */
1906 			if (dm_request_based(md))
1907 				r = md->queue->backing_dev_info.state &
1908 				    bdi_bits;
1909 			else
1910 				r = dm_table_any_congested(map, bdi_bits);
1911 		}
1912 		dm_put_live_table_fast(md);
1913 	}
1914 
1915 	return r;
1916 }
1917 
1918 /*-----------------------------------------------------------------
1919  * An IDR is used to keep track of allocated minor numbers.
1920  *---------------------------------------------------------------*/
1921 static void free_minor(int minor)
1922 {
1923 	spin_lock(&_minor_lock);
1924 	idr_remove(&_minor_idr, minor);
1925 	spin_unlock(&_minor_lock);
1926 }
1927 
1928 /*
1929  * See if the device with a specific minor # is free.
1930  */
1931 static int specific_minor(int minor)
1932 {
1933 	int r;
1934 
1935 	if (minor >= (1 << MINORBITS))
1936 		return -EINVAL;
1937 
1938 	idr_preload(GFP_KERNEL);
1939 	spin_lock(&_minor_lock);
1940 
1941 	r = idr_alloc(&_minor_idr, MINOR_ALLOCED, minor, minor + 1, GFP_NOWAIT);
1942 
1943 	spin_unlock(&_minor_lock);
1944 	idr_preload_end();
1945 	if (r < 0)
1946 		return r == -ENOSPC ? -EBUSY : r;
1947 	return 0;
1948 }
1949 
1950 static int next_free_minor(int *minor)
1951 {
1952 	int r;
1953 
1954 	idr_preload(GFP_KERNEL);
1955 	spin_lock(&_minor_lock);
1956 
1957 	r = idr_alloc(&_minor_idr, MINOR_ALLOCED, 0, 1 << MINORBITS, GFP_NOWAIT);
1958 
1959 	spin_unlock(&_minor_lock);
1960 	idr_preload_end();
1961 	if (r < 0)
1962 		return r;
1963 	*minor = r;
1964 	return 0;
1965 }
1966 
1967 static const struct block_device_operations dm_blk_dops;
1968 
1969 static void dm_wq_work(struct work_struct *work);
1970 
1971 static void dm_init_md_queue(struct mapped_device *md)
1972 {
1973 	/*
1974 	 * Request-based dm devices cannot be stacked on top of bio-based dm
1975 	 * devices.  The type of this dm device has not been decided yet.
1976 	 * The type is decided at the first table loading time.
1977 	 * To prevent problematic device stacking, clear the queue flag
1978 	 * for request stacking support until then.
1979 	 *
1980 	 * This queue is new, so no concurrency on the queue_flags.
1981 	 */
1982 	queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue);
1983 
1984 	md->queue->queuedata = md;
1985 	md->queue->backing_dev_info.congested_fn = dm_any_congested;
1986 	md->queue->backing_dev_info.congested_data = md;
1987 	blk_queue_make_request(md->queue, dm_request);
1988 	blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
1989 	blk_queue_merge_bvec(md->queue, dm_merge_bvec);
1990 }
1991 
1992 /*
1993  * Allocate and initialise a blank device with a given minor.
1994  */
1995 static struct mapped_device *alloc_dev(int minor)
1996 {
1997 	int r;
1998 	struct mapped_device *md = kzalloc(sizeof(*md), GFP_KERNEL);
1999 	void *old_md;
2000 
2001 	if (!md) {
2002 		DMWARN("unable to allocate device, out of memory.");
2003 		return NULL;
2004 	}
2005 
2006 	if (!try_module_get(THIS_MODULE))
2007 		goto bad_module_get;
2008 
2009 	/* get a minor number for the dev */
2010 	if (minor == DM_ANY_MINOR)
2011 		r = next_free_minor(&minor);
2012 	else
2013 		r = specific_minor(minor);
2014 	if (r < 0)
2015 		goto bad_minor;
2016 
2017 	r = init_srcu_struct(&md->io_barrier);
2018 	if (r < 0)
2019 		goto bad_io_barrier;
2020 
2021 	md->type = DM_TYPE_NONE;
2022 	mutex_init(&md->suspend_lock);
2023 	mutex_init(&md->type_lock);
2024 	spin_lock_init(&md->deferred_lock);
2025 	atomic_set(&md->holders, 1);
2026 	atomic_set(&md->open_count, 0);
2027 	atomic_set(&md->event_nr, 0);
2028 	atomic_set(&md->uevent_seq, 0);
2029 	INIT_LIST_HEAD(&md->uevent_list);
2030 	spin_lock_init(&md->uevent_lock);
2031 
2032 	md->queue = blk_alloc_queue(GFP_KERNEL);
2033 	if (!md->queue)
2034 		goto bad_queue;
2035 
2036 	dm_init_md_queue(md);
2037 
2038 	md->disk = alloc_disk(1);
2039 	if (!md->disk)
2040 		goto bad_disk;
2041 
2042 	atomic_set(&md->pending[0], 0);
2043 	atomic_set(&md->pending[1], 0);
2044 	init_waitqueue_head(&md->wait);
2045 	INIT_WORK(&md->work, dm_wq_work);
2046 	init_waitqueue_head(&md->eventq);
2047 	init_completion(&md->kobj_completion);
2048 
2049 	md->disk->major = _major;
2050 	md->disk->first_minor = minor;
2051 	md->disk->fops = &dm_blk_dops;
2052 	md->disk->queue = md->queue;
2053 	md->disk->private_data = md;
2054 	sprintf(md->disk->disk_name, "dm-%d", minor);
2055 	add_disk(md->disk);
2056 	format_dev_t(md->name, MKDEV(_major, minor));
2057 
2058 	md->wq = alloc_workqueue("kdmflush", WQ_MEM_RECLAIM, 0);
2059 	if (!md->wq)
2060 		goto bad_thread;
2061 
2062 	md->bdev = bdget_disk(md->disk, 0);
2063 	if (!md->bdev)
2064 		goto bad_bdev;
2065 
2066 	bio_init(&md->flush_bio);
2067 	md->flush_bio.bi_bdev = md->bdev;
2068 	md->flush_bio.bi_rw = WRITE_FLUSH;
2069 
2070 	dm_stats_init(&md->stats);
2071 
2072 	/* Populate the mapping, nobody knows we exist yet */
2073 	spin_lock(&_minor_lock);
2074 	old_md = idr_replace(&_minor_idr, md, minor);
2075 	spin_unlock(&_minor_lock);
2076 
2077 	BUG_ON(old_md != MINOR_ALLOCED);
2078 
2079 	return md;
2080 
2081 bad_bdev:
2082 	destroy_workqueue(md->wq);
2083 bad_thread:
2084 	del_gendisk(md->disk);
2085 	put_disk(md->disk);
2086 bad_disk:
2087 	blk_cleanup_queue(md->queue);
2088 bad_queue:
2089 	cleanup_srcu_struct(&md->io_barrier);
2090 bad_io_barrier:
2091 	free_minor(minor);
2092 bad_minor:
2093 	module_put(THIS_MODULE);
2094 bad_module_get:
2095 	kfree(md);
2096 	return NULL;
2097 }
2098 
2099 static void unlock_fs(struct mapped_device *md);
2100 
2101 static void free_dev(struct mapped_device *md)
2102 {
2103 	int minor = MINOR(disk_devt(md->disk));
2104 
2105 	unlock_fs(md);
2106 	bdput(md->bdev);
2107 	destroy_workqueue(md->wq);
2108 	if (md->io_pool)
2109 		mempool_destroy(md->io_pool);
2110 	if (md->bs)
2111 		bioset_free(md->bs);
2112 	blk_integrity_unregister(md->disk);
2113 	del_gendisk(md->disk);
2114 	cleanup_srcu_struct(&md->io_barrier);
2115 	free_minor(minor);
2116 
2117 	spin_lock(&_minor_lock);
2118 	md->disk->private_data = NULL;
2119 	spin_unlock(&_minor_lock);
2120 
2121 	put_disk(md->disk);
2122 	blk_cleanup_queue(md->queue);
2123 	dm_stats_cleanup(&md->stats);
2124 	module_put(THIS_MODULE);
2125 	kfree(md);
2126 }
2127 
2128 static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
2129 {
2130 	struct dm_md_mempools *p = dm_table_get_md_mempools(t);
2131 
2132 	if (md->io_pool && md->bs) {
2133 		/* The md already has necessary mempools. */
2134 		if (dm_table_get_type(t) == DM_TYPE_BIO_BASED) {
2135 			/*
2136 			 * Reload bioset because front_pad may have changed
2137 			 * because a different table was loaded.
2138 			 */
2139 			bioset_free(md->bs);
2140 			md->bs = p->bs;
2141 			p->bs = NULL;
2142 		} else if (dm_table_get_type(t) == DM_TYPE_REQUEST_BASED) {
2143 			/*
2144 			 * There's no need to reload with request-based dm
2145 			 * because the size of front_pad doesn't change.
2146 			 * Note for future: If you are to reload bioset,
2147 			 * prep-ed requests in the queue may refer
2148 			 * to bio from the old bioset, so you must walk
2149 			 * through the queue to unprep.
2150 			 */
2151 		}
2152 		goto out;
2153 	}
2154 
2155 	BUG_ON(!p || md->io_pool || md->bs);
2156 
2157 	md->io_pool = p->io_pool;
2158 	p->io_pool = NULL;
2159 	md->bs = p->bs;
2160 	p->bs = NULL;
2161 
2162 out:
2163 	/* mempool bind completed, now no need any mempools in the table */
2164 	dm_table_free_md_mempools(t);
2165 }
2166 
2167 /*
2168  * Bind a table to the device.
2169  */
2170 static void event_callback(void *context)
2171 {
2172 	unsigned long flags;
2173 	LIST_HEAD(uevents);
2174 	struct mapped_device *md = (struct mapped_device *) context;
2175 
2176 	spin_lock_irqsave(&md->uevent_lock, flags);
2177 	list_splice_init(&md->uevent_list, &uevents);
2178 	spin_unlock_irqrestore(&md->uevent_lock, flags);
2179 
2180 	dm_send_uevents(&uevents, &disk_to_dev(md->disk)->kobj);
2181 
2182 	atomic_inc(&md->event_nr);
2183 	wake_up(&md->eventq);
2184 }
2185 
2186 /*
2187  * Protected by md->suspend_lock obtained by dm_swap_table().
2188  */
2189 static void __set_size(struct mapped_device *md, sector_t size)
2190 {
2191 	set_capacity(md->disk, size);
2192 
2193 	i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
2194 }
2195 
2196 /*
2197  * Return 1 if the queue has a compulsory merge_bvec_fn function.
2198  *
2199  * If this function returns 0, then the device is either a non-dm
2200  * device without a merge_bvec_fn, or it is a dm device that is
2201  * able to split any bios it receives that are too big.
2202  */
2203 int dm_queue_merge_is_compulsory(struct request_queue *q)
2204 {
2205 	struct mapped_device *dev_md;
2206 
2207 	if (!q->merge_bvec_fn)
2208 		return 0;
2209 
2210 	if (q->make_request_fn == dm_request) {
2211 		dev_md = q->queuedata;
2212 		if (test_bit(DMF_MERGE_IS_OPTIONAL, &dev_md->flags))
2213 			return 0;
2214 	}
2215 
2216 	return 1;
2217 }
2218 
2219 static int dm_device_merge_is_compulsory(struct dm_target *ti,
2220 					 struct dm_dev *dev, sector_t start,
2221 					 sector_t len, void *data)
2222 {
2223 	struct block_device *bdev = dev->bdev;
2224 	struct request_queue *q = bdev_get_queue(bdev);
2225 
2226 	return dm_queue_merge_is_compulsory(q);
2227 }
2228 
2229 /*
2230  * Return 1 if it is acceptable to ignore merge_bvec_fn based
2231  * on the properties of the underlying devices.
2232  */
2233 static int dm_table_merge_is_optional(struct dm_table *table)
2234 {
2235 	unsigned i = 0;
2236 	struct dm_target *ti;
2237 
2238 	while (i < dm_table_get_num_targets(table)) {
2239 		ti = dm_table_get_target(table, i++);
2240 
2241 		if (ti->type->iterate_devices &&
2242 		    ti->type->iterate_devices(ti, dm_device_merge_is_compulsory, NULL))
2243 			return 0;
2244 	}
2245 
2246 	return 1;
2247 }
2248 
2249 /*
2250  * Returns old map, which caller must destroy.
2251  */
2252 static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
2253 			       struct queue_limits *limits)
2254 {
2255 	struct dm_table *old_map;
2256 	struct request_queue *q = md->queue;
2257 	sector_t size;
2258 	int merge_is_optional;
2259 
2260 	size = dm_table_get_size(t);
2261 
2262 	/*
2263 	 * Wipe any geometry if the size of the table changed.
2264 	 */
2265 	if (size != dm_get_size(md))
2266 		memset(&md->geometry, 0, sizeof(md->geometry));
2267 
2268 	__set_size(md, size);
2269 
2270 	dm_table_event_callback(t, event_callback, md);
2271 
2272 	/*
2273 	 * The queue hasn't been stopped yet, if the old table type wasn't
2274 	 * for request-based during suspension.  So stop it to prevent
2275 	 * I/O mapping before resume.
2276 	 * This must be done before setting the queue restrictions,
2277 	 * because request-based dm may be run just after the setting.
2278 	 */
2279 	if (dm_table_request_based(t) && !blk_queue_stopped(q))
2280 		stop_queue(q);
2281 
2282 	__bind_mempools(md, t);
2283 
2284 	merge_is_optional = dm_table_merge_is_optional(t);
2285 
2286 	old_map = md->map;
2287 	rcu_assign_pointer(md->map, t);
2288 	md->immutable_target_type = dm_table_get_immutable_target_type(t);
2289 
2290 	dm_table_set_restrictions(t, q, limits);
2291 	if (merge_is_optional)
2292 		set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
2293 	else
2294 		clear_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
2295 	dm_sync_table(md);
2296 
2297 	return old_map;
2298 }
2299 
2300 /*
2301  * Returns unbound table for the caller to free.
2302  */
2303 static struct dm_table *__unbind(struct mapped_device *md)
2304 {
2305 	struct dm_table *map = md->map;
2306 
2307 	if (!map)
2308 		return NULL;
2309 
2310 	dm_table_event_callback(map, NULL, NULL);
2311 	rcu_assign_pointer(md->map, NULL);
2312 	dm_sync_table(md);
2313 
2314 	return map;
2315 }
2316 
2317 /*
2318  * Constructor for a new device.
2319  */
2320 int dm_create(int minor, struct mapped_device **result)
2321 {
2322 	struct mapped_device *md;
2323 
2324 	md = alloc_dev(minor);
2325 	if (!md)
2326 		return -ENXIO;
2327 
2328 	dm_sysfs_init(md);
2329 
2330 	*result = md;
2331 	return 0;
2332 }
2333 
2334 /*
2335  * Functions to manage md->type.
2336  * All are required to hold md->type_lock.
2337  */
2338 void dm_lock_md_type(struct mapped_device *md)
2339 {
2340 	mutex_lock(&md->type_lock);
2341 }
2342 
2343 void dm_unlock_md_type(struct mapped_device *md)
2344 {
2345 	mutex_unlock(&md->type_lock);
2346 }
2347 
2348 void dm_set_md_type(struct mapped_device *md, unsigned type)
2349 {
2350 	BUG_ON(!mutex_is_locked(&md->type_lock));
2351 	md->type = type;
2352 }
2353 
2354 unsigned dm_get_md_type(struct mapped_device *md)
2355 {
2356 	BUG_ON(!mutex_is_locked(&md->type_lock));
2357 	return md->type;
2358 }
2359 
2360 struct target_type *dm_get_immutable_target_type(struct mapped_device *md)
2361 {
2362 	return md->immutable_target_type;
2363 }
2364 
2365 /*
2366  * The queue_limits are only valid as long as you have a reference
2367  * count on 'md'.
2368  */
2369 struct queue_limits *dm_get_queue_limits(struct mapped_device *md)
2370 {
2371 	BUG_ON(!atomic_read(&md->holders));
2372 	return &md->queue->limits;
2373 }
2374 EXPORT_SYMBOL_GPL(dm_get_queue_limits);
2375 
2376 /*
2377  * Fully initialize a request-based queue (->elevator, ->request_fn, etc).
2378  */
2379 static int dm_init_request_based_queue(struct mapped_device *md)
2380 {
2381 	struct request_queue *q = NULL;
2382 
2383 	if (md->queue->elevator)
2384 		return 1;
2385 
2386 	/* Fully initialize the queue */
2387 	q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL);
2388 	if (!q)
2389 		return 0;
2390 
2391 	md->queue = q;
2392 	dm_init_md_queue(md);
2393 	blk_queue_softirq_done(md->queue, dm_softirq_done);
2394 	blk_queue_prep_rq(md->queue, dm_prep_fn);
2395 	blk_queue_lld_busy(md->queue, dm_lld_busy);
2396 
2397 	elv_register_queue(md->queue);
2398 
2399 	return 1;
2400 }
2401 
2402 /*
2403  * Setup the DM device's queue based on md's type
2404  */
2405 int dm_setup_md_queue(struct mapped_device *md)
2406 {
2407 	if ((dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) &&
2408 	    !dm_init_request_based_queue(md)) {
2409 		DMWARN("Cannot initialize queue for request-based mapped device");
2410 		return -EINVAL;
2411 	}
2412 
2413 	return 0;
2414 }
2415 
2416 static struct mapped_device *dm_find_md(dev_t dev)
2417 {
2418 	struct mapped_device *md;
2419 	unsigned minor = MINOR(dev);
2420 
2421 	if (MAJOR(dev) != _major || minor >= (1 << MINORBITS))
2422 		return NULL;
2423 
2424 	spin_lock(&_minor_lock);
2425 
2426 	md = idr_find(&_minor_idr, minor);
2427 	if (md && (md == MINOR_ALLOCED ||
2428 		   (MINOR(disk_devt(dm_disk(md))) != minor) ||
2429 		   dm_deleting_md(md) ||
2430 		   test_bit(DMF_FREEING, &md->flags))) {
2431 		md = NULL;
2432 		goto out;
2433 	}
2434 
2435 out:
2436 	spin_unlock(&_minor_lock);
2437 
2438 	return md;
2439 }
2440 
2441 struct mapped_device *dm_get_md(dev_t dev)
2442 {
2443 	struct mapped_device *md = dm_find_md(dev);
2444 
2445 	if (md)
2446 		dm_get(md);
2447 
2448 	return md;
2449 }
2450 EXPORT_SYMBOL_GPL(dm_get_md);
2451 
2452 void *dm_get_mdptr(struct mapped_device *md)
2453 {
2454 	return md->interface_ptr;
2455 }
2456 
2457 void dm_set_mdptr(struct mapped_device *md, void *ptr)
2458 {
2459 	md->interface_ptr = ptr;
2460 }
2461 
2462 void dm_get(struct mapped_device *md)
2463 {
2464 	atomic_inc(&md->holders);
2465 	BUG_ON(test_bit(DMF_FREEING, &md->flags));
2466 }
2467 
2468 const char *dm_device_name(struct mapped_device *md)
2469 {
2470 	return md->name;
2471 }
2472 EXPORT_SYMBOL_GPL(dm_device_name);
2473 
2474 static void __dm_destroy(struct mapped_device *md, bool wait)
2475 {
2476 	struct dm_table *map;
2477 	int srcu_idx;
2478 
2479 	might_sleep();
2480 
2481 	spin_lock(&_minor_lock);
2482 	map = dm_get_live_table(md, &srcu_idx);
2483 	idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md))));
2484 	set_bit(DMF_FREEING, &md->flags);
2485 	spin_unlock(&_minor_lock);
2486 
2487 	if (!dm_suspended_md(md)) {
2488 		dm_table_presuspend_targets(map);
2489 		dm_table_postsuspend_targets(map);
2490 	}
2491 
2492 	/* dm_put_live_table must be before msleep, otherwise deadlock is possible */
2493 	dm_put_live_table(md, srcu_idx);
2494 
2495 	/*
2496 	 * Rare, but there may be I/O requests still going to complete,
2497 	 * for example.  Wait for all references to disappear.
2498 	 * No one should increment the reference count of the mapped_device,
2499 	 * after the mapped_device state becomes DMF_FREEING.
2500 	 */
2501 	if (wait)
2502 		while (atomic_read(&md->holders))
2503 			msleep(1);
2504 	else if (atomic_read(&md->holders))
2505 		DMWARN("%s: Forcibly removing mapped_device still in use! (%d users)",
2506 		       dm_device_name(md), atomic_read(&md->holders));
2507 
2508 	dm_sysfs_exit(md);
2509 	dm_table_destroy(__unbind(md));
2510 	free_dev(md);
2511 }
2512 
2513 void dm_destroy(struct mapped_device *md)
2514 {
2515 	__dm_destroy(md, true);
2516 }
2517 
2518 void dm_destroy_immediate(struct mapped_device *md)
2519 {
2520 	__dm_destroy(md, false);
2521 }
2522 
2523 void dm_put(struct mapped_device *md)
2524 {
2525 	atomic_dec(&md->holders);
2526 }
2527 EXPORT_SYMBOL_GPL(dm_put);
2528 
2529 static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
2530 {
2531 	int r = 0;
2532 	DECLARE_WAITQUEUE(wait, current);
2533 
2534 	add_wait_queue(&md->wait, &wait);
2535 
2536 	while (1) {
2537 		set_current_state(interruptible);
2538 
2539 		if (!md_in_flight(md))
2540 			break;
2541 
2542 		if (interruptible == TASK_INTERRUPTIBLE &&
2543 		    signal_pending(current)) {
2544 			r = -EINTR;
2545 			break;
2546 		}
2547 
2548 		io_schedule();
2549 	}
2550 	set_current_state(TASK_RUNNING);
2551 
2552 	remove_wait_queue(&md->wait, &wait);
2553 
2554 	return r;
2555 }
2556 
2557 /*
2558  * Process the deferred bios
2559  */
2560 static void dm_wq_work(struct work_struct *work)
2561 {
2562 	struct mapped_device *md = container_of(work, struct mapped_device,
2563 						work);
2564 	struct bio *c;
2565 	int srcu_idx;
2566 	struct dm_table *map;
2567 
2568 	map = dm_get_live_table(md, &srcu_idx);
2569 
2570 	while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
2571 		spin_lock_irq(&md->deferred_lock);
2572 		c = bio_list_pop(&md->deferred);
2573 		spin_unlock_irq(&md->deferred_lock);
2574 
2575 		if (!c)
2576 			break;
2577 
2578 		if (dm_request_based(md))
2579 			generic_make_request(c);
2580 		else
2581 			__split_and_process_bio(md, map, c);
2582 	}
2583 
2584 	dm_put_live_table(md, srcu_idx);
2585 }
2586 
2587 static void dm_queue_flush(struct mapped_device *md)
2588 {
2589 	clear_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
2590 	smp_mb__after_clear_bit();
2591 	queue_work(md->wq, &md->work);
2592 }
2593 
2594 /*
2595  * Swap in a new table, returning the old one for the caller to destroy.
2596  */
2597 struct dm_table *dm_swap_table(struct mapped_device *md, struct dm_table *table)
2598 {
2599 	struct dm_table *live_map = NULL, *map = ERR_PTR(-EINVAL);
2600 	struct queue_limits limits;
2601 	int r;
2602 
2603 	mutex_lock(&md->suspend_lock);
2604 
2605 	/* device must be suspended */
2606 	if (!dm_suspended_md(md))
2607 		goto out;
2608 
2609 	/*
2610 	 * If the new table has no data devices, retain the existing limits.
2611 	 * This helps multipath with queue_if_no_path if all paths disappear,
2612 	 * then new I/O is queued based on these limits, and then some paths
2613 	 * reappear.
2614 	 */
2615 	if (dm_table_has_no_data_devices(table)) {
2616 		live_map = dm_get_live_table_fast(md);
2617 		if (live_map)
2618 			limits = md->queue->limits;
2619 		dm_put_live_table_fast(md);
2620 	}
2621 
2622 	if (!live_map) {
2623 		r = dm_calculate_queue_limits(table, &limits);
2624 		if (r) {
2625 			map = ERR_PTR(r);
2626 			goto out;
2627 		}
2628 	}
2629 
2630 	map = __bind(md, table, &limits);
2631 
2632 out:
2633 	mutex_unlock(&md->suspend_lock);
2634 	return map;
2635 }
2636 
2637 /*
2638  * Functions to lock and unlock any filesystem running on the
2639  * device.
2640  */
2641 static int lock_fs(struct mapped_device *md)
2642 {
2643 	int r;
2644 
2645 	WARN_ON(md->frozen_sb);
2646 
2647 	md->frozen_sb = freeze_bdev(md->bdev);
2648 	if (IS_ERR(md->frozen_sb)) {
2649 		r = PTR_ERR(md->frozen_sb);
2650 		md->frozen_sb = NULL;
2651 		return r;
2652 	}
2653 
2654 	set_bit(DMF_FROZEN, &md->flags);
2655 
2656 	return 0;
2657 }
2658 
2659 static void unlock_fs(struct mapped_device *md)
2660 {
2661 	if (!test_bit(DMF_FROZEN, &md->flags))
2662 		return;
2663 
2664 	thaw_bdev(md->bdev, md->frozen_sb);
2665 	md->frozen_sb = NULL;
2666 	clear_bit(DMF_FROZEN, &md->flags);
2667 }
2668 
2669 /*
2670  * We need to be able to change a mapping table under a mounted
2671  * filesystem.  For example we might want to move some data in
2672  * the background.  Before the table can be swapped with
2673  * dm_bind_table, dm_suspend must be called to flush any in
2674  * flight bios and ensure that any further io gets deferred.
2675  */
2676 /*
2677  * Suspend mechanism in request-based dm.
2678  *
2679  * 1. Flush all I/Os by lock_fs() if needed.
2680  * 2. Stop dispatching any I/O by stopping the request_queue.
2681  * 3. Wait for all in-flight I/Os to be completed or requeued.
2682  *
2683  * To abort suspend, start the request_queue.
2684  */
2685 int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
2686 {
2687 	struct dm_table *map = NULL;
2688 	int r = 0;
2689 	int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0;
2690 	int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0;
2691 
2692 	mutex_lock(&md->suspend_lock);
2693 
2694 	if (dm_suspended_md(md)) {
2695 		r = -EINVAL;
2696 		goto out_unlock;
2697 	}
2698 
2699 	map = md->map;
2700 
2701 	/*
2702 	 * DMF_NOFLUSH_SUSPENDING must be set before presuspend.
2703 	 * This flag is cleared before dm_suspend returns.
2704 	 */
2705 	if (noflush)
2706 		set_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
2707 
2708 	/* This does not get reverted if there's an error later. */
2709 	dm_table_presuspend_targets(map);
2710 
2711 	/*
2712 	 * Flush I/O to the device.
2713 	 * Any I/O submitted after lock_fs() may not be flushed.
2714 	 * noflush takes precedence over do_lockfs.
2715 	 * (lock_fs() flushes I/Os and waits for them to complete.)
2716 	 */
2717 	if (!noflush && do_lockfs) {
2718 		r = lock_fs(md);
2719 		if (r)
2720 			goto out_unlock;
2721 	}
2722 
2723 	/*
2724 	 * Here we must make sure that no processes are submitting requests
2725 	 * to target drivers i.e. no one may be executing
2726 	 * __split_and_process_bio. This is called from dm_request and
2727 	 * dm_wq_work.
2728 	 *
2729 	 * To get all processes out of __split_and_process_bio in dm_request,
2730 	 * we take the write lock. To prevent any process from reentering
2731 	 * __split_and_process_bio from dm_request and quiesce the thread
2732 	 * (dm_wq_work), we set BMF_BLOCK_IO_FOR_SUSPEND and call
2733 	 * flush_workqueue(md->wq).
2734 	 */
2735 	set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
2736 	synchronize_srcu(&md->io_barrier);
2737 
2738 	/*
2739 	 * Stop md->queue before flushing md->wq in case request-based
2740 	 * dm defers requests to md->wq from md->queue.
2741 	 */
2742 	if (dm_request_based(md))
2743 		stop_queue(md->queue);
2744 
2745 	flush_workqueue(md->wq);
2746 
2747 	/*
2748 	 * At this point no more requests are entering target request routines.
2749 	 * We call dm_wait_for_completion to wait for all existing requests
2750 	 * to finish.
2751 	 */
2752 	r = dm_wait_for_completion(md, TASK_INTERRUPTIBLE);
2753 
2754 	if (noflush)
2755 		clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
2756 	synchronize_srcu(&md->io_barrier);
2757 
2758 	/* were we interrupted ? */
2759 	if (r < 0) {
2760 		dm_queue_flush(md);
2761 
2762 		if (dm_request_based(md))
2763 			start_queue(md->queue);
2764 
2765 		unlock_fs(md);
2766 		goto out_unlock; /* pushback list is already flushed, so skip flush */
2767 	}
2768 
2769 	/*
2770 	 * If dm_wait_for_completion returned 0, the device is completely
2771 	 * quiescent now. There is no request-processing activity. All new
2772 	 * requests are being added to md->deferred list.
2773 	 */
2774 
2775 	set_bit(DMF_SUSPENDED, &md->flags);
2776 
2777 	dm_table_postsuspend_targets(map);
2778 
2779 out_unlock:
2780 	mutex_unlock(&md->suspend_lock);
2781 	return r;
2782 }
2783 
2784 int dm_resume(struct mapped_device *md)
2785 {
2786 	int r = -EINVAL;
2787 	struct dm_table *map = NULL;
2788 
2789 	mutex_lock(&md->suspend_lock);
2790 	if (!dm_suspended_md(md))
2791 		goto out;
2792 
2793 	map = md->map;
2794 	if (!map || !dm_table_get_size(map))
2795 		goto out;
2796 
2797 	r = dm_table_resume_targets(map);
2798 	if (r)
2799 		goto out;
2800 
2801 	dm_queue_flush(md);
2802 
2803 	/*
2804 	 * Flushing deferred I/Os must be done after targets are resumed
2805 	 * so that mapping of targets can work correctly.
2806 	 * Request-based dm is queueing the deferred I/Os in its request_queue.
2807 	 */
2808 	if (dm_request_based(md))
2809 		start_queue(md->queue);
2810 
2811 	unlock_fs(md);
2812 
2813 	clear_bit(DMF_SUSPENDED, &md->flags);
2814 
2815 	r = 0;
2816 out:
2817 	mutex_unlock(&md->suspend_lock);
2818 
2819 	return r;
2820 }
2821 
2822 /*
2823  * Internal suspend/resume works like userspace-driven suspend. It waits
2824  * until all bios finish and prevents issuing new bios to the target drivers.
2825  * It may be used only from the kernel.
2826  *
2827  * Internal suspend holds md->suspend_lock, which prevents interaction with
2828  * userspace-driven suspend.
2829  */
2830 
2831 void dm_internal_suspend(struct mapped_device *md)
2832 {
2833 	mutex_lock(&md->suspend_lock);
2834 	if (dm_suspended_md(md))
2835 		return;
2836 
2837 	set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
2838 	synchronize_srcu(&md->io_barrier);
2839 	flush_workqueue(md->wq);
2840 	dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
2841 }
2842 
2843 void dm_internal_resume(struct mapped_device *md)
2844 {
2845 	if (dm_suspended_md(md))
2846 		goto done;
2847 
2848 	dm_queue_flush(md);
2849 
2850 done:
2851 	mutex_unlock(&md->suspend_lock);
2852 }
2853 
2854 /*-----------------------------------------------------------------
2855  * Event notification.
2856  *---------------------------------------------------------------*/
2857 int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
2858 		       unsigned cookie)
2859 {
2860 	char udev_cookie[DM_COOKIE_LENGTH];
2861 	char *envp[] = { udev_cookie, NULL };
2862 
2863 	if (!cookie)
2864 		return kobject_uevent(&disk_to_dev(md->disk)->kobj, action);
2865 	else {
2866 		snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u",
2867 			 DM_COOKIE_ENV_VAR_NAME, cookie);
2868 		return kobject_uevent_env(&disk_to_dev(md->disk)->kobj,
2869 					  action, envp);
2870 	}
2871 }
2872 
2873 uint32_t dm_next_uevent_seq(struct mapped_device *md)
2874 {
2875 	return atomic_add_return(1, &md->uevent_seq);
2876 }
2877 
2878 uint32_t dm_get_event_nr(struct mapped_device *md)
2879 {
2880 	return atomic_read(&md->event_nr);
2881 }
2882 
2883 int dm_wait_event(struct mapped_device *md, int event_nr)
2884 {
2885 	return wait_event_interruptible(md->eventq,
2886 			(event_nr != atomic_read(&md->event_nr)));
2887 }
2888 
2889 void dm_uevent_add(struct mapped_device *md, struct list_head *elist)
2890 {
2891 	unsigned long flags;
2892 
2893 	spin_lock_irqsave(&md->uevent_lock, flags);
2894 	list_add(elist, &md->uevent_list);
2895 	spin_unlock_irqrestore(&md->uevent_lock, flags);
2896 }
2897 
2898 /*
2899  * The gendisk is only valid as long as you have a reference
2900  * count on 'md'.
2901  */
2902 struct gendisk *dm_disk(struct mapped_device *md)
2903 {
2904 	return md->disk;
2905 }
2906 
2907 struct kobject *dm_kobject(struct mapped_device *md)
2908 {
2909 	return &md->kobj;
2910 }
2911 
2912 struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
2913 {
2914 	struct mapped_device *md;
2915 
2916 	md = container_of(kobj, struct mapped_device, kobj);
2917 
2918 	if (test_bit(DMF_FREEING, &md->flags) ||
2919 	    dm_deleting_md(md))
2920 		return NULL;
2921 
2922 	dm_get(md);
2923 	return md;
2924 }
2925 
2926 struct completion *dm_get_completion_from_kobject(struct kobject *kobj)
2927 {
2928 	struct mapped_device *md = container_of(kobj, struct mapped_device, kobj);
2929 
2930 	return &md->kobj_completion;
2931 }
2932 
2933 int dm_suspended_md(struct mapped_device *md)
2934 {
2935 	return test_bit(DMF_SUSPENDED, &md->flags);
2936 }
2937 
2938 int dm_test_deferred_remove_flag(struct mapped_device *md)
2939 {
2940 	return test_bit(DMF_DEFERRED_REMOVE, &md->flags);
2941 }
2942 
2943 int dm_suspended(struct dm_target *ti)
2944 {
2945 	return dm_suspended_md(dm_table_get_md(ti->table));
2946 }
2947 EXPORT_SYMBOL_GPL(dm_suspended);
2948 
2949 int dm_noflush_suspending(struct dm_target *ti)
2950 {
2951 	return __noflush_suspending(dm_table_get_md(ti->table));
2952 }
2953 EXPORT_SYMBOL_GPL(dm_noflush_suspending);
2954 
2955 struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, unsigned per_bio_data_size)
2956 {
2957 	struct dm_md_mempools *pools = kzalloc(sizeof(*pools), GFP_KERNEL);
2958 	struct kmem_cache *cachep;
2959 	unsigned int pool_size;
2960 	unsigned int front_pad;
2961 
2962 	if (!pools)
2963 		return NULL;
2964 
2965 	if (type == DM_TYPE_BIO_BASED) {
2966 		cachep = _io_cache;
2967 		pool_size = dm_get_reserved_bio_based_ios();
2968 		front_pad = roundup(per_bio_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone);
2969 	} else if (type == DM_TYPE_REQUEST_BASED) {
2970 		cachep = _rq_tio_cache;
2971 		pool_size = dm_get_reserved_rq_based_ios();
2972 		front_pad = offsetof(struct dm_rq_clone_bio_info, clone);
2973 		/* per_bio_data_size is not used. See __bind_mempools(). */
2974 		WARN_ON(per_bio_data_size != 0);
2975 	} else
2976 		goto out;
2977 
2978 	pools->io_pool = mempool_create_slab_pool(pool_size, cachep);
2979 	if (!pools->io_pool)
2980 		goto out;
2981 
2982 	pools->bs = bioset_create(pool_size, front_pad);
2983 	if (!pools->bs)
2984 		goto out;
2985 
2986 	if (integrity && bioset_integrity_create(pools->bs, pool_size))
2987 		goto out;
2988 
2989 	return pools;
2990 
2991 out:
2992 	dm_free_md_mempools(pools);
2993 
2994 	return NULL;
2995 }
2996 
2997 void dm_free_md_mempools(struct dm_md_mempools *pools)
2998 {
2999 	if (!pools)
3000 		return;
3001 
3002 	if (pools->io_pool)
3003 		mempool_destroy(pools->io_pool);
3004 
3005 	if (pools->bs)
3006 		bioset_free(pools->bs);
3007 
3008 	kfree(pools);
3009 }
3010 
3011 static const struct block_device_operations dm_blk_dops = {
3012 	.open = dm_blk_open,
3013 	.release = dm_blk_close,
3014 	.ioctl = dm_blk_ioctl,
3015 	.getgeo = dm_blk_getgeo,
3016 	.owner = THIS_MODULE
3017 };
3018 
3019 EXPORT_SYMBOL(dm_get_mapinfo);
3020 
3021 /*
3022  * module hooks
3023  */
3024 module_init(dm_init);
3025 module_exit(dm_exit);
3026 
3027 module_param(major, uint, 0);
3028 MODULE_PARM_DESC(major, "The major number of the device mapper");
3029 
3030 module_param(reserved_bio_based_ios, uint, S_IRUGO | S_IWUSR);
3031 MODULE_PARM_DESC(reserved_bio_based_ios, "Reserved IOs in bio-based mempools");
3032 
3033 module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
3034 MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
3035 
3036 MODULE_DESCRIPTION(DM_NAME " driver");
3037 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
3038 MODULE_LICENSE("GPL");
3039