xref: /linux/drivers/md/dm.c (revision d39d0ed196aa1685bb24771e92f78633c66ac9cb)
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/buffer_head.h>
18 #include <linux/smp_lock.h>
19 #include <linux/mempool.h>
20 #include <linux/slab.h>
21 #include <linux/idr.h>
22 #include <linux/hdreg.h>
23 #include <linux/delay.h>
24 
25 #include <trace/events/block.h>
26 
27 #define DM_MSG_PREFIX "core"
28 
29 /*
30  * Cookies are numeric values sent with CHANGE and REMOVE
31  * uevents while resuming, removing or renaming the device.
32  */
33 #define DM_COOKIE_ENV_VAR_NAME "DM_COOKIE"
34 #define DM_COOKIE_LENGTH 24
35 
36 static const char *_name = DM_NAME;
37 
38 static unsigned int major = 0;
39 static unsigned int _major = 0;
40 
41 static DEFINE_SPINLOCK(_minor_lock);
42 /*
43  * For bio-based dm.
44  * One of these is allocated per bio.
45  */
46 struct dm_io {
47 	struct mapped_device *md;
48 	int error;
49 	atomic_t io_count;
50 	struct bio *bio;
51 	unsigned long start_time;
52 	spinlock_t endio_lock;
53 };
54 
55 /*
56  * For bio-based dm.
57  * One of these is allocated per target within a bio.  Hopefully
58  * this will be simplified out one day.
59  */
60 struct dm_target_io {
61 	struct dm_io *io;
62 	struct dm_target *ti;
63 	union map_info info;
64 };
65 
66 /*
67  * For request-based dm.
68  * One of these is allocated per request.
69  */
70 struct dm_rq_target_io {
71 	struct mapped_device *md;
72 	struct dm_target *ti;
73 	struct request *orig, clone;
74 	int error;
75 	union map_info info;
76 };
77 
78 /*
79  * For request-based dm.
80  * One of these is allocated per bio.
81  */
82 struct dm_rq_clone_bio_info {
83 	struct bio *orig;
84 	struct dm_rq_target_io *tio;
85 };
86 
87 union map_info *dm_get_mapinfo(struct bio *bio)
88 {
89 	if (bio && bio->bi_private)
90 		return &((struct dm_target_io *)bio->bi_private)->info;
91 	return NULL;
92 }
93 
94 union map_info *dm_get_rq_mapinfo(struct request *rq)
95 {
96 	if (rq && rq->end_io_data)
97 		return &((struct dm_rq_target_io *)rq->end_io_data)->info;
98 	return NULL;
99 }
100 EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo);
101 
102 #define MINOR_ALLOCED ((void *)-1)
103 
104 /*
105  * Bits for the md->flags field.
106  */
107 #define DMF_BLOCK_IO_FOR_SUSPEND 0
108 #define DMF_SUSPENDED 1
109 #define DMF_FROZEN 2
110 #define DMF_FREEING 3
111 #define DMF_DELETING 4
112 #define DMF_NOFLUSH_SUSPENDING 5
113 #define DMF_QUEUE_IO_TO_THREAD 6
114 
115 /*
116  * Work processed by per-device workqueue.
117  */
118 struct mapped_device {
119 	struct rw_semaphore io_lock;
120 	struct mutex suspend_lock;
121 	rwlock_t map_lock;
122 	atomic_t holders;
123 	atomic_t open_count;
124 
125 	unsigned long flags;
126 
127 	struct request_queue *queue;
128 	unsigned type;
129 	/* Protect queue and type against concurrent access. */
130 	struct mutex type_lock;
131 
132 	struct gendisk *disk;
133 	char name[16];
134 
135 	void *interface_ptr;
136 
137 	/*
138 	 * A list of ios that arrived while we were suspended.
139 	 */
140 	atomic_t pending[2];
141 	wait_queue_head_t wait;
142 	struct work_struct work;
143 	struct bio_list deferred;
144 	spinlock_t deferred_lock;
145 
146 	/*
147 	 * An error from the barrier request currently being processed.
148 	 */
149 	int barrier_error;
150 
151 	/*
152 	 * Protect barrier_error from concurrent endio processing
153 	 * in request-based dm.
154 	 */
155 	spinlock_t barrier_error_lock;
156 
157 	/*
158 	 * Processing queue (flush/barriers)
159 	 */
160 	struct workqueue_struct *wq;
161 	struct work_struct barrier_work;
162 
163 	/* A pointer to the currently processing pre/post flush request */
164 	struct request *flush_request;
165 
166 	/*
167 	 * The current mapping.
168 	 */
169 	struct dm_table *map;
170 
171 	/*
172 	 * io objects are allocated from here.
173 	 */
174 	mempool_t *io_pool;
175 	mempool_t *tio_pool;
176 
177 	struct bio_set *bs;
178 
179 	/*
180 	 * Event handling.
181 	 */
182 	atomic_t event_nr;
183 	wait_queue_head_t eventq;
184 	atomic_t uevent_seq;
185 	struct list_head uevent_list;
186 	spinlock_t uevent_lock; /* Protect access to uevent_list */
187 
188 	/*
189 	 * freeze/thaw support require holding onto a super block
190 	 */
191 	struct super_block *frozen_sb;
192 	struct block_device *bdev;
193 
194 	/* forced geometry settings */
195 	struct hd_geometry geometry;
196 
197 	/* For saving the address of __make_request for request based dm */
198 	make_request_fn *saved_make_request_fn;
199 
200 	/* sysfs handle */
201 	struct kobject kobj;
202 
203 	/* zero-length barrier that will be cloned and submitted to targets */
204 	struct bio barrier_bio;
205 };
206 
207 /*
208  * For mempools pre-allocation at the table loading time.
209  */
210 struct dm_md_mempools {
211 	mempool_t *io_pool;
212 	mempool_t *tio_pool;
213 	struct bio_set *bs;
214 };
215 
216 #define MIN_IOS 256
217 static struct kmem_cache *_io_cache;
218 static struct kmem_cache *_tio_cache;
219 static struct kmem_cache *_rq_tio_cache;
220 static struct kmem_cache *_rq_bio_info_cache;
221 
222 static int __init local_init(void)
223 {
224 	int r = -ENOMEM;
225 
226 	/* allocate a slab for the dm_ios */
227 	_io_cache = KMEM_CACHE(dm_io, 0);
228 	if (!_io_cache)
229 		return r;
230 
231 	/* allocate a slab for the target ios */
232 	_tio_cache = KMEM_CACHE(dm_target_io, 0);
233 	if (!_tio_cache)
234 		goto out_free_io_cache;
235 
236 	_rq_tio_cache = KMEM_CACHE(dm_rq_target_io, 0);
237 	if (!_rq_tio_cache)
238 		goto out_free_tio_cache;
239 
240 	_rq_bio_info_cache = KMEM_CACHE(dm_rq_clone_bio_info, 0);
241 	if (!_rq_bio_info_cache)
242 		goto out_free_rq_tio_cache;
243 
244 	r = dm_uevent_init();
245 	if (r)
246 		goto out_free_rq_bio_info_cache;
247 
248 	_major = major;
249 	r = register_blkdev(_major, _name);
250 	if (r < 0)
251 		goto out_uevent_exit;
252 
253 	if (!_major)
254 		_major = r;
255 
256 	return 0;
257 
258 out_uevent_exit:
259 	dm_uevent_exit();
260 out_free_rq_bio_info_cache:
261 	kmem_cache_destroy(_rq_bio_info_cache);
262 out_free_rq_tio_cache:
263 	kmem_cache_destroy(_rq_tio_cache);
264 out_free_tio_cache:
265 	kmem_cache_destroy(_tio_cache);
266 out_free_io_cache:
267 	kmem_cache_destroy(_io_cache);
268 
269 	return r;
270 }
271 
272 static void local_exit(void)
273 {
274 	kmem_cache_destroy(_rq_bio_info_cache);
275 	kmem_cache_destroy(_rq_tio_cache);
276 	kmem_cache_destroy(_tio_cache);
277 	kmem_cache_destroy(_io_cache);
278 	unregister_blkdev(_major, _name);
279 	dm_uevent_exit();
280 
281 	_major = 0;
282 
283 	DMINFO("cleaned up");
284 }
285 
286 static int (*_inits[])(void) __initdata = {
287 	local_init,
288 	dm_target_init,
289 	dm_linear_init,
290 	dm_stripe_init,
291 	dm_io_init,
292 	dm_kcopyd_init,
293 	dm_interface_init,
294 };
295 
296 static void (*_exits[])(void) = {
297 	local_exit,
298 	dm_target_exit,
299 	dm_linear_exit,
300 	dm_stripe_exit,
301 	dm_io_exit,
302 	dm_kcopyd_exit,
303 	dm_interface_exit,
304 };
305 
306 static int __init dm_init(void)
307 {
308 	const int count = ARRAY_SIZE(_inits);
309 
310 	int r, i;
311 
312 	for (i = 0; i < count; i++) {
313 		r = _inits[i]();
314 		if (r)
315 			goto bad;
316 	}
317 
318 	return 0;
319 
320       bad:
321 	while (i--)
322 		_exits[i]();
323 
324 	return r;
325 }
326 
327 static void __exit dm_exit(void)
328 {
329 	int i = ARRAY_SIZE(_exits);
330 
331 	while (i--)
332 		_exits[i]();
333 }
334 
335 /*
336  * Block device functions
337  */
338 int dm_deleting_md(struct mapped_device *md)
339 {
340 	return test_bit(DMF_DELETING, &md->flags);
341 }
342 
343 static int dm_blk_open(struct block_device *bdev, fmode_t mode)
344 {
345 	struct mapped_device *md;
346 
347 	lock_kernel();
348 	spin_lock(&_minor_lock);
349 
350 	md = bdev->bd_disk->private_data;
351 	if (!md)
352 		goto out;
353 
354 	if (test_bit(DMF_FREEING, &md->flags) ||
355 	    dm_deleting_md(md)) {
356 		md = NULL;
357 		goto out;
358 	}
359 
360 	dm_get(md);
361 	atomic_inc(&md->open_count);
362 
363 out:
364 	spin_unlock(&_minor_lock);
365 	unlock_kernel();
366 
367 	return md ? 0 : -ENXIO;
368 }
369 
370 static int dm_blk_close(struct gendisk *disk, fmode_t mode)
371 {
372 	struct mapped_device *md = disk->private_data;
373 
374 	lock_kernel();
375 	atomic_dec(&md->open_count);
376 	dm_put(md);
377 	unlock_kernel();
378 
379 	return 0;
380 }
381 
382 int dm_open_count(struct mapped_device *md)
383 {
384 	return atomic_read(&md->open_count);
385 }
386 
387 /*
388  * Guarantees nothing is using the device before it's deleted.
389  */
390 int dm_lock_for_deletion(struct mapped_device *md)
391 {
392 	int r = 0;
393 
394 	spin_lock(&_minor_lock);
395 
396 	if (dm_open_count(md))
397 		r = -EBUSY;
398 	else
399 		set_bit(DMF_DELETING, &md->flags);
400 
401 	spin_unlock(&_minor_lock);
402 
403 	return r;
404 }
405 
406 static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
407 {
408 	struct mapped_device *md = bdev->bd_disk->private_data;
409 
410 	return dm_get_geometry(md, geo);
411 }
412 
413 static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode,
414 			unsigned int cmd, unsigned long arg)
415 {
416 	struct mapped_device *md = bdev->bd_disk->private_data;
417 	struct dm_table *map = dm_get_live_table(md);
418 	struct dm_target *tgt;
419 	int r = -ENOTTY;
420 
421 	if (!map || !dm_table_get_size(map))
422 		goto out;
423 
424 	/* We only support devices that have a single target */
425 	if (dm_table_get_num_targets(map) != 1)
426 		goto out;
427 
428 	tgt = dm_table_get_target(map, 0);
429 
430 	if (dm_suspended_md(md)) {
431 		r = -EAGAIN;
432 		goto out;
433 	}
434 
435 	if (tgt->type->ioctl)
436 		r = tgt->type->ioctl(tgt, cmd, arg);
437 
438 out:
439 	dm_table_put(map);
440 
441 	return r;
442 }
443 
444 static struct dm_io *alloc_io(struct mapped_device *md)
445 {
446 	return mempool_alloc(md->io_pool, GFP_NOIO);
447 }
448 
449 static void free_io(struct mapped_device *md, struct dm_io *io)
450 {
451 	mempool_free(io, md->io_pool);
452 }
453 
454 static void free_tio(struct mapped_device *md, struct dm_target_io *tio)
455 {
456 	mempool_free(tio, md->tio_pool);
457 }
458 
459 static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md,
460 					    gfp_t gfp_mask)
461 {
462 	return mempool_alloc(md->tio_pool, gfp_mask);
463 }
464 
465 static void free_rq_tio(struct dm_rq_target_io *tio)
466 {
467 	mempool_free(tio, tio->md->tio_pool);
468 }
469 
470 static struct dm_rq_clone_bio_info *alloc_bio_info(struct mapped_device *md)
471 {
472 	return mempool_alloc(md->io_pool, GFP_ATOMIC);
473 }
474 
475 static void free_bio_info(struct dm_rq_clone_bio_info *info)
476 {
477 	mempool_free(info, info->tio->md->io_pool);
478 }
479 
480 static int md_in_flight(struct mapped_device *md)
481 {
482 	return atomic_read(&md->pending[READ]) +
483 	       atomic_read(&md->pending[WRITE]);
484 }
485 
486 static void start_io_acct(struct dm_io *io)
487 {
488 	struct mapped_device *md = io->md;
489 	int cpu;
490 	int rw = bio_data_dir(io->bio);
491 
492 	io->start_time = jiffies;
493 
494 	cpu = part_stat_lock();
495 	part_round_stats(cpu, &dm_disk(md)->part0);
496 	part_stat_unlock();
497 	dm_disk(md)->part0.in_flight[rw] = atomic_inc_return(&md->pending[rw]);
498 }
499 
500 static void end_io_acct(struct dm_io *io)
501 {
502 	struct mapped_device *md = io->md;
503 	struct bio *bio = io->bio;
504 	unsigned long duration = jiffies - io->start_time;
505 	int pending, cpu;
506 	int rw = bio_data_dir(bio);
507 
508 	cpu = part_stat_lock();
509 	part_round_stats(cpu, &dm_disk(md)->part0);
510 	part_stat_add(cpu, &dm_disk(md)->part0, ticks[rw], duration);
511 	part_stat_unlock();
512 
513 	/*
514 	 * After this is decremented the bio must not be touched if it is
515 	 * a barrier.
516 	 */
517 	dm_disk(md)->part0.in_flight[rw] = pending =
518 		atomic_dec_return(&md->pending[rw]);
519 	pending += atomic_read(&md->pending[rw^0x1]);
520 
521 	/* nudge anyone waiting on suspend queue */
522 	if (!pending)
523 		wake_up(&md->wait);
524 }
525 
526 /*
527  * Add the bio to the list of deferred io.
528  */
529 static void queue_io(struct mapped_device *md, struct bio *bio)
530 {
531 	down_write(&md->io_lock);
532 
533 	spin_lock_irq(&md->deferred_lock);
534 	bio_list_add(&md->deferred, bio);
535 	spin_unlock_irq(&md->deferred_lock);
536 
537 	if (!test_and_set_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags))
538 		queue_work(md->wq, &md->work);
539 
540 	up_write(&md->io_lock);
541 }
542 
543 /*
544  * Everyone (including functions in this file), should use this
545  * function to access the md->map field, and make sure they call
546  * dm_table_put() when finished.
547  */
548 struct dm_table *dm_get_live_table(struct mapped_device *md)
549 {
550 	struct dm_table *t;
551 	unsigned long flags;
552 
553 	read_lock_irqsave(&md->map_lock, flags);
554 	t = md->map;
555 	if (t)
556 		dm_table_get(t);
557 	read_unlock_irqrestore(&md->map_lock, flags);
558 
559 	return t;
560 }
561 
562 /*
563  * Get the geometry associated with a dm device
564  */
565 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo)
566 {
567 	*geo = md->geometry;
568 
569 	return 0;
570 }
571 
572 /*
573  * Set the geometry of a device.
574  */
575 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo)
576 {
577 	sector_t sz = (sector_t)geo->cylinders * geo->heads * geo->sectors;
578 
579 	if (geo->start > sz) {
580 		DMWARN("Start sector is beyond the geometry limits.");
581 		return -EINVAL;
582 	}
583 
584 	md->geometry = *geo;
585 
586 	return 0;
587 }
588 
589 /*-----------------------------------------------------------------
590  * CRUD START:
591  *   A more elegant soln is in the works that uses the queue
592  *   merge fn, unfortunately there are a couple of changes to
593  *   the block layer that I want to make for this.  So in the
594  *   interests of getting something for people to use I give
595  *   you this clearly demarcated crap.
596  *---------------------------------------------------------------*/
597 
598 static int __noflush_suspending(struct mapped_device *md)
599 {
600 	return test_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
601 }
602 
603 /*
604  * Decrements the number of outstanding ios that a bio has been
605  * cloned into, completing the original io if necc.
606  */
607 static void dec_pending(struct dm_io *io, int error)
608 {
609 	unsigned long flags;
610 	int io_error;
611 	struct bio *bio;
612 	struct mapped_device *md = io->md;
613 
614 	/* Push-back supersedes any I/O errors */
615 	if (unlikely(error)) {
616 		spin_lock_irqsave(&io->endio_lock, flags);
617 		if (!(io->error > 0 && __noflush_suspending(md)))
618 			io->error = error;
619 		spin_unlock_irqrestore(&io->endio_lock, flags);
620 	}
621 
622 	if (atomic_dec_and_test(&io->io_count)) {
623 		if (io->error == DM_ENDIO_REQUEUE) {
624 			/*
625 			 * Target requested pushing back the I/O.
626 			 */
627 			spin_lock_irqsave(&md->deferred_lock, flags);
628 			if (__noflush_suspending(md)) {
629 				if (!(io->bio->bi_rw & REQ_HARDBARRIER))
630 					bio_list_add_head(&md->deferred,
631 							  io->bio);
632 			} else
633 				/* noflush suspend was interrupted. */
634 				io->error = -EIO;
635 			spin_unlock_irqrestore(&md->deferred_lock, flags);
636 		}
637 
638 		io_error = io->error;
639 		bio = io->bio;
640 
641 		if (bio->bi_rw & REQ_HARDBARRIER) {
642 			/*
643 			 * There can be just one barrier request so we use
644 			 * a per-device variable for error reporting.
645 			 * Note that you can't touch the bio after end_io_acct
646 			 *
647 			 * We ignore -EOPNOTSUPP for empty flush reported by
648 			 * underlying devices. We assume that if the device
649 			 * doesn't support empty barriers, it doesn't need
650 			 * cache flushing commands.
651 			 */
652 			if (!md->barrier_error &&
653 			    !(bio_empty_barrier(bio) && io_error == -EOPNOTSUPP))
654 				md->barrier_error = io_error;
655 			end_io_acct(io);
656 			free_io(md, io);
657 		} else {
658 			end_io_acct(io);
659 			free_io(md, io);
660 
661 			if (io_error != DM_ENDIO_REQUEUE) {
662 				trace_block_bio_complete(md->queue, bio);
663 
664 				bio_endio(bio, io_error);
665 			}
666 		}
667 	}
668 }
669 
670 static void clone_endio(struct bio *bio, int error)
671 {
672 	int r = 0;
673 	struct dm_target_io *tio = bio->bi_private;
674 	struct dm_io *io = tio->io;
675 	struct mapped_device *md = tio->io->md;
676 	dm_endio_fn endio = tio->ti->type->end_io;
677 
678 	if (!bio_flagged(bio, BIO_UPTODATE) && !error)
679 		error = -EIO;
680 
681 	if (endio) {
682 		r = endio(tio->ti, bio, error, &tio->info);
683 		if (r < 0 || r == DM_ENDIO_REQUEUE)
684 			/*
685 			 * error and requeue request are handled
686 			 * in dec_pending().
687 			 */
688 			error = r;
689 		else if (r == DM_ENDIO_INCOMPLETE)
690 			/* The target will handle the io */
691 			return;
692 		else if (r) {
693 			DMWARN("unimplemented target endio return value: %d", r);
694 			BUG();
695 		}
696 	}
697 
698 	/*
699 	 * Store md for cleanup instead of tio which is about to get freed.
700 	 */
701 	bio->bi_private = md->bs;
702 
703 	free_tio(md, tio);
704 	bio_put(bio);
705 	dec_pending(io, error);
706 }
707 
708 /*
709  * Partial completion handling for request-based dm
710  */
711 static void end_clone_bio(struct bio *clone, int error)
712 {
713 	struct dm_rq_clone_bio_info *info = clone->bi_private;
714 	struct dm_rq_target_io *tio = info->tio;
715 	struct bio *bio = info->orig;
716 	unsigned int nr_bytes = info->orig->bi_size;
717 
718 	bio_put(clone);
719 
720 	if (tio->error)
721 		/*
722 		 * An error has already been detected on the request.
723 		 * Once error occurred, just let clone->end_io() handle
724 		 * the remainder.
725 		 */
726 		return;
727 	else if (error) {
728 		/*
729 		 * Don't notice the error to the upper layer yet.
730 		 * The error handling decision is made by the target driver,
731 		 * when the request is completed.
732 		 */
733 		tio->error = error;
734 		return;
735 	}
736 
737 	/*
738 	 * I/O for the bio successfully completed.
739 	 * Notice the data completion to the upper layer.
740 	 */
741 
742 	/*
743 	 * bios are processed from the head of the list.
744 	 * So the completing bio should always be rq->bio.
745 	 * If it's not, something wrong is happening.
746 	 */
747 	if (tio->orig->bio != bio)
748 		DMERR("bio completion is going in the middle of the request");
749 
750 	/*
751 	 * Update the original request.
752 	 * Do not use blk_end_request() here, because it may complete
753 	 * the original request before the clone, and break the ordering.
754 	 */
755 	blk_update_request(tio->orig, 0, nr_bytes);
756 }
757 
758 static void store_barrier_error(struct mapped_device *md, int error)
759 {
760 	unsigned long flags;
761 
762 	spin_lock_irqsave(&md->barrier_error_lock, flags);
763 	/*
764 	 * Basically, the first error is taken, but:
765 	 *   -EOPNOTSUPP supersedes any I/O error.
766 	 *   Requeue request supersedes any I/O error but -EOPNOTSUPP.
767 	 */
768 	if (!md->barrier_error || error == -EOPNOTSUPP ||
769 	    (md->barrier_error != -EOPNOTSUPP &&
770 	     error == DM_ENDIO_REQUEUE))
771 		md->barrier_error = error;
772 	spin_unlock_irqrestore(&md->barrier_error_lock, flags);
773 }
774 
775 /*
776  * Don't touch any member of the md after calling this function because
777  * the md may be freed in dm_put() at the end of this function.
778  * Or do dm_get() before calling this function and dm_put() later.
779  */
780 static void rq_completed(struct mapped_device *md, int rw, int run_queue)
781 {
782 	atomic_dec(&md->pending[rw]);
783 
784 	/* nudge anyone waiting on suspend queue */
785 	if (!md_in_flight(md))
786 		wake_up(&md->wait);
787 
788 	if (run_queue)
789 		blk_run_queue(md->queue);
790 
791 	/*
792 	 * dm_put() must be at the end of this function. See the comment above
793 	 */
794 	dm_put(md);
795 }
796 
797 static void free_rq_clone(struct request *clone)
798 {
799 	struct dm_rq_target_io *tio = clone->end_io_data;
800 
801 	blk_rq_unprep_clone(clone);
802 	free_rq_tio(tio);
803 }
804 
805 /*
806  * Complete the clone and the original request.
807  * Must be called without queue lock.
808  */
809 static void dm_end_request(struct request *clone, int error)
810 {
811 	int rw = rq_data_dir(clone);
812 	int run_queue = 1;
813 	bool is_barrier = clone->cmd_flags & REQ_HARDBARRIER;
814 	struct dm_rq_target_io *tio = clone->end_io_data;
815 	struct mapped_device *md = tio->md;
816 	struct request *rq = tio->orig;
817 
818 	if (rq->cmd_type == REQ_TYPE_BLOCK_PC && !is_barrier) {
819 		rq->errors = clone->errors;
820 		rq->resid_len = clone->resid_len;
821 
822 		if (rq->sense)
823 			/*
824 			 * We are using the sense buffer of the original
825 			 * request.
826 			 * So setting the length of the sense data is enough.
827 			 */
828 			rq->sense_len = clone->sense_len;
829 	}
830 
831 	free_rq_clone(clone);
832 
833 	if (unlikely(is_barrier)) {
834 		if (unlikely(error))
835 			store_barrier_error(md, error);
836 		run_queue = 0;
837 	} else
838 		blk_end_request_all(rq, error);
839 
840 	rq_completed(md, rw, run_queue);
841 }
842 
843 static void dm_unprep_request(struct request *rq)
844 {
845 	struct request *clone = rq->special;
846 
847 	rq->special = NULL;
848 	rq->cmd_flags &= ~REQ_DONTPREP;
849 
850 	free_rq_clone(clone);
851 }
852 
853 /*
854  * Requeue the original request of a clone.
855  */
856 void dm_requeue_unmapped_request(struct request *clone)
857 {
858 	int rw = rq_data_dir(clone);
859 	struct dm_rq_target_io *tio = clone->end_io_data;
860 	struct mapped_device *md = tio->md;
861 	struct request *rq = tio->orig;
862 	struct request_queue *q = rq->q;
863 	unsigned long flags;
864 
865 	if (unlikely(clone->cmd_flags & REQ_HARDBARRIER)) {
866 		/*
867 		 * Barrier clones share an original request.
868 		 * Leave it to dm_end_request(), which handles this special
869 		 * case.
870 		 */
871 		dm_end_request(clone, DM_ENDIO_REQUEUE);
872 		return;
873 	}
874 
875 	dm_unprep_request(rq);
876 
877 	spin_lock_irqsave(q->queue_lock, flags);
878 	if (elv_queue_empty(q))
879 		blk_plug_device(q);
880 	blk_requeue_request(q, rq);
881 	spin_unlock_irqrestore(q->queue_lock, flags);
882 
883 	rq_completed(md, rw, 0);
884 }
885 EXPORT_SYMBOL_GPL(dm_requeue_unmapped_request);
886 
887 static void __stop_queue(struct request_queue *q)
888 {
889 	blk_stop_queue(q);
890 }
891 
892 static void stop_queue(struct request_queue *q)
893 {
894 	unsigned long flags;
895 
896 	spin_lock_irqsave(q->queue_lock, flags);
897 	__stop_queue(q);
898 	spin_unlock_irqrestore(q->queue_lock, flags);
899 }
900 
901 static void __start_queue(struct request_queue *q)
902 {
903 	if (blk_queue_stopped(q))
904 		blk_start_queue(q);
905 }
906 
907 static void start_queue(struct request_queue *q)
908 {
909 	unsigned long flags;
910 
911 	spin_lock_irqsave(q->queue_lock, flags);
912 	__start_queue(q);
913 	spin_unlock_irqrestore(q->queue_lock, flags);
914 }
915 
916 static void dm_done(struct request *clone, int error, bool mapped)
917 {
918 	int r = error;
919 	struct dm_rq_target_io *tio = clone->end_io_data;
920 	dm_request_endio_fn rq_end_io = tio->ti->type->rq_end_io;
921 
922 	if (mapped && rq_end_io)
923 		r = rq_end_io(tio->ti, clone, error, &tio->info);
924 
925 	if (r <= 0)
926 		/* The target wants to complete the I/O */
927 		dm_end_request(clone, r);
928 	else if (r == DM_ENDIO_INCOMPLETE)
929 		/* The target will handle the I/O */
930 		return;
931 	else if (r == DM_ENDIO_REQUEUE)
932 		/* The target wants to requeue the I/O */
933 		dm_requeue_unmapped_request(clone);
934 	else {
935 		DMWARN("unimplemented target endio return value: %d", r);
936 		BUG();
937 	}
938 }
939 
940 /*
941  * Request completion handler for request-based dm
942  */
943 static void dm_softirq_done(struct request *rq)
944 {
945 	bool mapped = true;
946 	struct request *clone = rq->completion_data;
947 	struct dm_rq_target_io *tio = clone->end_io_data;
948 
949 	if (rq->cmd_flags & REQ_FAILED)
950 		mapped = false;
951 
952 	dm_done(clone, tio->error, mapped);
953 }
954 
955 /*
956  * Complete the clone and the original request with the error status
957  * through softirq context.
958  */
959 static void dm_complete_request(struct request *clone, int error)
960 {
961 	struct dm_rq_target_io *tio = clone->end_io_data;
962 	struct request *rq = tio->orig;
963 
964 	if (unlikely(clone->cmd_flags & REQ_HARDBARRIER)) {
965 		/*
966 		 * Barrier clones share an original request.  So can't use
967 		 * softirq_done with the original.
968 		 * Pass the clone to dm_done() directly in this special case.
969 		 * It is safe (even if clone->q->queue_lock is held here)
970 		 * because there is no I/O dispatching during the completion
971 		 * of barrier clone.
972 		 */
973 		dm_done(clone, error, true);
974 		return;
975 	}
976 
977 	tio->error = error;
978 	rq->completion_data = clone;
979 	blk_complete_request(rq);
980 }
981 
982 /*
983  * Complete the not-mapped clone and the original request with the error status
984  * through softirq context.
985  * Target's rq_end_io() function isn't called.
986  * This may be used when the target's map_rq() function fails.
987  */
988 void dm_kill_unmapped_request(struct request *clone, int error)
989 {
990 	struct dm_rq_target_io *tio = clone->end_io_data;
991 	struct request *rq = tio->orig;
992 
993 	if (unlikely(clone->cmd_flags & REQ_HARDBARRIER)) {
994 		/*
995 		 * Barrier clones share an original request.
996 		 * Leave it to dm_end_request(), which handles this special
997 		 * case.
998 		 */
999 		BUG_ON(error > 0);
1000 		dm_end_request(clone, error);
1001 		return;
1002 	}
1003 
1004 	rq->cmd_flags |= REQ_FAILED;
1005 	dm_complete_request(clone, error);
1006 }
1007 EXPORT_SYMBOL_GPL(dm_kill_unmapped_request);
1008 
1009 /*
1010  * Called with the queue lock held
1011  */
1012 static void end_clone_request(struct request *clone, int error)
1013 {
1014 	/*
1015 	 * For just cleaning up the information of the queue in which
1016 	 * the clone was dispatched.
1017 	 * The clone is *NOT* freed actually here because it is alloced from
1018 	 * dm own mempool and REQ_ALLOCED isn't set in clone->cmd_flags.
1019 	 */
1020 	__blk_put_request(clone->q, clone);
1021 
1022 	/*
1023 	 * Actual request completion is done in a softirq context which doesn't
1024 	 * hold the queue lock.  Otherwise, deadlock could occur because:
1025 	 *     - another request may be submitted by the upper level driver
1026 	 *       of the stacking during the completion
1027 	 *     - the submission which requires queue lock may be done
1028 	 *       against this queue
1029 	 */
1030 	dm_complete_request(clone, error);
1031 }
1032 
1033 /*
1034  * Return maximum size of I/O possible at the supplied sector up to the current
1035  * target boundary.
1036  */
1037 static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti)
1038 {
1039 	sector_t target_offset = dm_target_offset(ti, sector);
1040 
1041 	return ti->len - target_offset;
1042 }
1043 
1044 static sector_t max_io_len(sector_t sector, struct dm_target *ti)
1045 {
1046 	sector_t len = max_io_len_target_boundary(sector, ti);
1047 
1048 	/*
1049 	 * Does the target need to split even further ?
1050 	 */
1051 	if (ti->split_io) {
1052 		sector_t boundary;
1053 		sector_t offset = dm_target_offset(ti, sector);
1054 		boundary = ((offset + ti->split_io) & ~(ti->split_io - 1))
1055 			   - offset;
1056 		if (len > boundary)
1057 			len = boundary;
1058 	}
1059 
1060 	return len;
1061 }
1062 
1063 static void __map_bio(struct dm_target *ti, struct bio *clone,
1064 		      struct dm_target_io *tio)
1065 {
1066 	int r;
1067 	sector_t sector;
1068 	struct mapped_device *md;
1069 
1070 	clone->bi_end_io = clone_endio;
1071 	clone->bi_private = tio;
1072 
1073 	/*
1074 	 * Map the clone.  If r == 0 we don't need to do
1075 	 * anything, the target has assumed ownership of
1076 	 * this io.
1077 	 */
1078 	atomic_inc(&tio->io->io_count);
1079 	sector = clone->bi_sector;
1080 	r = ti->type->map(ti, clone, &tio->info);
1081 	if (r == DM_MAPIO_REMAPPED) {
1082 		/* the bio has been remapped so dispatch it */
1083 
1084 		trace_block_remap(bdev_get_queue(clone->bi_bdev), clone,
1085 				    tio->io->bio->bi_bdev->bd_dev, sector);
1086 
1087 		generic_make_request(clone);
1088 	} else if (r < 0 || r == DM_MAPIO_REQUEUE) {
1089 		/* error the io and bail out, or requeue it if needed */
1090 		md = tio->io->md;
1091 		dec_pending(tio->io, r);
1092 		/*
1093 		 * Store bio_set for cleanup.
1094 		 */
1095 		clone->bi_private = md->bs;
1096 		bio_put(clone);
1097 		free_tio(md, tio);
1098 	} else if (r) {
1099 		DMWARN("unimplemented target map return value: %d", r);
1100 		BUG();
1101 	}
1102 }
1103 
1104 struct clone_info {
1105 	struct mapped_device *md;
1106 	struct dm_table *map;
1107 	struct bio *bio;
1108 	struct dm_io *io;
1109 	sector_t sector;
1110 	sector_t sector_count;
1111 	unsigned short idx;
1112 };
1113 
1114 static void dm_bio_destructor(struct bio *bio)
1115 {
1116 	struct bio_set *bs = bio->bi_private;
1117 
1118 	bio_free(bio, bs);
1119 }
1120 
1121 /*
1122  * Creates a little bio that is just does part of a bvec.
1123  */
1124 static struct bio *split_bvec(struct bio *bio, sector_t sector,
1125 			      unsigned short idx, unsigned int offset,
1126 			      unsigned int len, struct bio_set *bs)
1127 {
1128 	struct bio *clone;
1129 	struct bio_vec *bv = bio->bi_io_vec + idx;
1130 
1131 	clone = bio_alloc_bioset(GFP_NOIO, 1, bs);
1132 	clone->bi_destructor = dm_bio_destructor;
1133 	*clone->bi_io_vec = *bv;
1134 
1135 	clone->bi_sector = sector;
1136 	clone->bi_bdev = bio->bi_bdev;
1137 	clone->bi_rw = bio->bi_rw & ~REQ_HARDBARRIER;
1138 	clone->bi_vcnt = 1;
1139 	clone->bi_size = to_bytes(len);
1140 	clone->bi_io_vec->bv_offset = offset;
1141 	clone->bi_io_vec->bv_len = clone->bi_size;
1142 	clone->bi_flags |= 1 << BIO_CLONED;
1143 
1144 	if (bio_integrity(bio)) {
1145 		bio_integrity_clone(clone, bio, GFP_NOIO, bs);
1146 		bio_integrity_trim(clone,
1147 				   bio_sector_offset(bio, idx, offset), len);
1148 	}
1149 
1150 	return clone;
1151 }
1152 
1153 /*
1154  * Creates a bio that consists of range of complete bvecs.
1155  */
1156 static struct bio *clone_bio(struct bio *bio, sector_t sector,
1157 			     unsigned short idx, unsigned short bv_count,
1158 			     unsigned int len, struct bio_set *bs)
1159 {
1160 	struct bio *clone;
1161 
1162 	clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);
1163 	__bio_clone(clone, bio);
1164 	clone->bi_rw &= ~REQ_HARDBARRIER;
1165 	clone->bi_destructor = dm_bio_destructor;
1166 	clone->bi_sector = sector;
1167 	clone->bi_idx = idx;
1168 	clone->bi_vcnt = idx + bv_count;
1169 	clone->bi_size = to_bytes(len);
1170 	clone->bi_flags &= ~(1 << BIO_SEG_VALID);
1171 
1172 	if (bio_integrity(bio)) {
1173 		bio_integrity_clone(clone, bio, GFP_NOIO, bs);
1174 
1175 		if (idx != bio->bi_idx || clone->bi_size < bio->bi_size)
1176 			bio_integrity_trim(clone,
1177 					   bio_sector_offset(bio, idx, 0), len);
1178 	}
1179 
1180 	return clone;
1181 }
1182 
1183 static struct dm_target_io *alloc_tio(struct clone_info *ci,
1184 				      struct dm_target *ti)
1185 {
1186 	struct dm_target_io *tio = mempool_alloc(ci->md->tio_pool, GFP_NOIO);
1187 
1188 	tio->io = ci->io;
1189 	tio->ti = ti;
1190 	memset(&tio->info, 0, sizeof(tio->info));
1191 
1192 	return tio;
1193 }
1194 
1195 static void __issue_target_request(struct clone_info *ci, struct dm_target *ti,
1196 				   unsigned request_nr, sector_t len)
1197 {
1198 	struct dm_target_io *tio = alloc_tio(ci, ti);
1199 	struct bio *clone;
1200 
1201 	tio->info.target_request_nr = request_nr;
1202 
1203 	/*
1204 	 * Discard requests require the bio's inline iovecs be initialized.
1205 	 * ci->bio->bi_max_vecs is BIO_INLINE_VECS anyway, for both flush
1206 	 * and discard, so no need for concern about wasted bvec allocations.
1207 	 */
1208 	clone = bio_alloc_bioset(GFP_NOIO, ci->bio->bi_max_vecs, ci->md->bs);
1209 	__bio_clone(clone, ci->bio);
1210 	clone->bi_destructor = dm_bio_destructor;
1211 	if (len) {
1212 		clone->bi_sector = ci->sector;
1213 		clone->bi_size = to_bytes(len);
1214 	}
1215 
1216 	__map_bio(ti, clone, tio);
1217 }
1218 
1219 static void __issue_target_requests(struct clone_info *ci, struct dm_target *ti,
1220 				    unsigned num_requests, sector_t len)
1221 {
1222 	unsigned request_nr;
1223 
1224 	for (request_nr = 0; request_nr < num_requests; request_nr++)
1225 		__issue_target_request(ci, ti, request_nr, len);
1226 }
1227 
1228 static int __clone_and_map_empty_barrier(struct clone_info *ci)
1229 {
1230 	unsigned target_nr = 0;
1231 	struct dm_target *ti;
1232 
1233 	while ((ti = dm_table_get_target(ci->map, target_nr++)))
1234 		__issue_target_requests(ci, ti, ti->num_flush_requests, 0);
1235 
1236 	ci->sector_count = 0;
1237 
1238 	return 0;
1239 }
1240 
1241 /*
1242  * Perform all io with a single clone.
1243  */
1244 static void __clone_and_map_simple(struct clone_info *ci, struct dm_target *ti)
1245 {
1246 	struct bio *clone, *bio = ci->bio;
1247 	struct dm_target_io *tio;
1248 
1249 	tio = alloc_tio(ci, ti);
1250 	clone = clone_bio(bio, ci->sector, ci->idx,
1251 			  bio->bi_vcnt - ci->idx, ci->sector_count,
1252 			  ci->md->bs);
1253 	__map_bio(ti, clone, tio);
1254 	ci->sector_count = 0;
1255 }
1256 
1257 static int __clone_and_map_discard(struct clone_info *ci)
1258 {
1259 	struct dm_target *ti;
1260 	sector_t len;
1261 
1262 	do {
1263 		ti = dm_table_find_target(ci->map, ci->sector);
1264 		if (!dm_target_is_valid(ti))
1265 			return -EIO;
1266 
1267 		/*
1268 		 * Even though the device advertised discard support,
1269 		 * reconfiguration might have changed that since the
1270 		 * check was performed.
1271 		 */
1272 		if (!ti->num_discard_requests)
1273 			return -EOPNOTSUPP;
1274 
1275 		len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
1276 
1277 		__issue_target_requests(ci, ti, ti->num_discard_requests, len);
1278 
1279 		ci->sector += len;
1280 	} while (ci->sector_count -= len);
1281 
1282 	return 0;
1283 }
1284 
1285 static int __clone_and_map(struct clone_info *ci)
1286 {
1287 	struct bio *clone, *bio = ci->bio;
1288 	struct dm_target *ti;
1289 	sector_t len = 0, max;
1290 	struct dm_target_io *tio;
1291 
1292 	if (unlikely(bio_empty_barrier(bio)))
1293 		return __clone_and_map_empty_barrier(ci);
1294 
1295 	if (unlikely(bio->bi_rw & REQ_DISCARD))
1296 		return __clone_and_map_discard(ci);
1297 
1298 	ti = dm_table_find_target(ci->map, ci->sector);
1299 	if (!dm_target_is_valid(ti))
1300 		return -EIO;
1301 
1302 	max = max_io_len(ci->sector, ti);
1303 
1304 	if (ci->sector_count <= max) {
1305 		/*
1306 		 * Optimise for the simple case where we can do all of
1307 		 * the remaining io with a single clone.
1308 		 */
1309 		__clone_and_map_simple(ci, ti);
1310 
1311 	} else if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) {
1312 		/*
1313 		 * There are some bvecs that don't span targets.
1314 		 * Do as many of these as possible.
1315 		 */
1316 		int i;
1317 		sector_t remaining = max;
1318 		sector_t bv_len;
1319 
1320 		for (i = ci->idx; remaining && (i < bio->bi_vcnt); i++) {
1321 			bv_len = to_sector(bio->bi_io_vec[i].bv_len);
1322 
1323 			if (bv_len > remaining)
1324 				break;
1325 
1326 			remaining -= bv_len;
1327 			len += bv_len;
1328 		}
1329 
1330 		tio = alloc_tio(ci, ti);
1331 		clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len,
1332 				  ci->md->bs);
1333 		__map_bio(ti, clone, tio);
1334 
1335 		ci->sector += len;
1336 		ci->sector_count -= len;
1337 		ci->idx = i;
1338 
1339 	} else {
1340 		/*
1341 		 * Handle a bvec that must be split between two or more targets.
1342 		 */
1343 		struct bio_vec *bv = bio->bi_io_vec + ci->idx;
1344 		sector_t remaining = to_sector(bv->bv_len);
1345 		unsigned int offset = 0;
1346 
1347 		do {
1348 			if (offset) {
1349 				ti = dm_table_find_target(ci->map, ci->sector);
1350 				if (!dm_target_is_valid(ti))
1351 					return -EIO;
1352 
1353 				max = max_io_len(ci->sector, ti);
1354 			}
1355 
1356 			len = min(remaining, max);
1357 
1358 			tio = alloc_tio(ci, ti);
1359 			clone = split_bvec(bio, ci->sector, ci->idx,
1360 					   bv->bv_offset + offset, len,
1361 					   ci->md->bs);
1362 
1363 			__map_bio(ti, clone, tio);
1364 
1365 			ci->sector += len;
1366 			ci->sector_count -= len;
1367 			offset += to_bytes(len);
1368 		} while (remaining -= len);
1369 
1370 		ci->idx++;
1371 	}
1372 
1373 	return 0;
1374 }
1375 
1376 /*
1377  * Split the bio into several clones and submit it to targets.
1378  */
1379 static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
1380 {
1381 	struct clone_info ci;
1382 	int error = 0;
1383 
1384 	ci.map = dm_get_live_table(md);
1385 	if (unlikely(!ci.map)) {
1386 		if (!(bio->bi_rw & REQ_HARDBARRIER))
1387 			bio_io_error(bio);
1388 		else
1389 			if (!md->barrier_error)
1390 				md->barrier_error = -EIO;
1391 		return;
1392 	}
1393 
1394 	ci.md = md;
1395 	ci.bio = bio;
1396 	ci.io = alloc_io(md);
1397 	ci.io->error = 0;
1398 	atomic_set(&ci.io->io_count, 1);
1399 	ci.io->bio = bio;
1400 	ci.io->md = md;
1401 	spin_lock_init(&ci.io->endio_lock);
1402 	ci.sector = bio->bi_sector;
1403 	ci.sector_count = bio_sectors(bio);
1404 	if (unlikely(bio_empty_barrier(bio)))
1405 		ci.sector_count = 1;
1406 	ci.idx = bio->bi_idx;
1407 
1408 	start_io_acct(ci.io);
1409 	while (ci.sector_count && !error)
1410 		error = __clone_and_map(&ci);
1411 
1412 	/* drop the extra reference count */
1413 	dec_pending(ci.io, error);
1414 	dm_table_put(ci.map);
1415 }
1416 /*-----------------------------------------------------------------
1417  * CRUD END
1418  *---------------------------------------------------------------*/
1419 
1420 static int dm_merge_bvec(struct request_queue *q,
1421 			 struct bvec_merge_data *bvm,
1422 			 struct bio_vec *biovec)
1423 {
1424 	struct mapped_device *md = q->queuedata;
1425 	struct dm_table *map = dm_get_live_table(md);
1426 	struct dm_target *ti;
1427 	sector_t max_sectors;
1428 	int max_size = 0;
1429 
1430 	if (unlikely(!map))
1431 		goto out;
1432 
1433 	ti = dm_table_find_target(map, bvm->bi_sector);
1434 	if (!dm_target_is_valid(ti))
1435 		goto out_table;
1436 
1437 	/*
1438 	 * Find maximum amount of I/O that won't need splitting
1439 	 */
1440 	max_sectors = min(max_io_len(bvm->bi_sector, ti),
1441 			  (sector_t) BIO_MAX_SECTORS);
1442 	max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
1443 	if (max_size < 0)
1444 		max_size = 0;
1445 
1446 	/*
1447 	 * merge_bvec_fn() returns number of bytes
1448 	 * it can accept at this offset
1449 	 * max is precomputed maximal io size
1450 	 */
1451 	if (max_size && ti->type->merge)
1452 		max_size = ti->type->merge(ti, bvm, biovec, max_size);
1453 	/*
1454 	 * If the target doesn't support merge method and some of the devices
1455 	 * provided their merge_bvec method (we know this by looking at
1456 	 * queue_max_hw_sectors), then we can't allow bios with multiple vector
1457 	 * entries.  So always set max_size to 0, and the code below allows
1458 	 * just one page.
1459 	 */
1460 	else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9)
1461 
1462 		max_size = 0;
1463 
1464 out_table:
1465 	dm_table_put(map);
1466 
1467 out:
1468 	/*
1469 	 * Always allow an entire first page
1470 	 */
1471 	if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT))
1472 		max_size = biovec->bv_len;
1473 
1474 	return max_size;
1475 }
1476 
1477 /*
1478  * The request function that just remaps the bio built up by
1479  * dm_merge_bvec.
1480  */
1481 static int _dm_request(struct request_queue *q, struct bio *bio)
1482 {
1483 	int rw = bio_data_dir(bio);
1484 	struct mapped_device *md = q->queuedata;
1485 	int cpu;
1486 
1487 	down_read(&md->io_lock);
1488 
1489 	cpu = part_stat_lock();
1490 	part_stat_inc(cpu, &dm_disk(md)->part0, ios[rw]);
1491 	part_stat_add(cpu, &dm_disk(md)->part0, sectors[rw], bio_sectors(bio));
1492 	part_stat_unlock();
1493 
1494 	/*
1495 	 * If we're suspended or the thread is processing barriers
1496 	 * we have to queue this io for later.
1497 	 */
1498 	if (unlikely(test_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags)) ||
1499 	    unlikely(bio->bi_rw & REQ_HARDBARRIER)) {
1500 		up_read(&md->io_lock);
1501 
1502 		if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) &&
1503 		    bio_rw(bio) == READA) {
1504 			bio_io_error(bio);
1505 			return 0;
1506 		}
1507 
1508 		queue_io(md, bio);
1509 
1510 		return 0;
1511 	}
1512 
1513 	__split_and_process_bio(md, bio);
1514 	up_read(&md->io_lock);
1515 	return 0;
1516 }
1517 
1518 static int dm_make_request(struct request_queue *q, struct bio *bio)
1519 {
1520 	struct mapped_device *md = q->queuedata;
1521 
1522 	return md->saved_make_request_fn(q, bio); /* call __make_request() */
1523 }
1524 
1525 static int dm_request_based(struct mapped_device *md)
1526 {
1527 	return blk_queue_stackable(md->queue);
1528 }
1529 
1530 static int dm_request(struct request_queue *q, struct bio *bio)
1531 {
1532 	struct mapped_device *md = q->queuedata;
1533 
1534 	if (dm_request_based(md))
1535 		return dm_make_request(q, bio);
1536 
1537 	return _dm_request(q, bio);
1538 }
1539 
1540 static bool dm_rq_is_flush_request(struct request *rq)
1541 {
1542 	if (rq->cmd_flags & REQ_FLUSH)
1543 		return true;
1544 	else
1545 		return false;
1546 }
1547 
1548 void dm_dispatch_request(struct request *rq)
1549 {
1550 	int r;
1551 
1552 	if (blk_queue_io_stat(rq->q))
1553 		rq->cmd_flags |= REQ_IO_STAT;
1554 
1555 	rq->start_time = jiffies;
1556 	r = blk_insert_cloned_request(rq->q, rq);
1557 	if (r)
1558 		dm_complete_request(rq, r);
1559 }
1560 EXPORT_SYMBOL_GPL(dm_dispatch_request);
1561 
1562 static void dm_rq_bio_destructor(struct bio *bio)
1563 {
1564 	struct dm_rq_clone_bio_info *info = bio->bi_private;
1565 	struct mapped_device *md = info->tio->md;
1566 
1567 	free_bio_info(info);
1568 	bio_free(bio, md->bs);
1569 }
1570 
1571 static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
1572 				 void *data)
1573 {
1574 	struct dm_rq_target_io *tio = data;
1575 	struct mapped_device *md = tio->md;
1576 	struct dm_rq_clone_bio_info *info = alloc_bio_info(md);
1577 
1578 	if (!info)
1579 		return -ENOMEM;
1580 
1581 	info->orig = bio_orig;
1582 	info->tio = tio;
1583 	bio->bi_end_io = end_clone_bio;
1584 	bio->bi_private = info;
1585 	bio->bi_destructor = dm_rq_bio_destructor;
1586 
1587 	return 0;
1588 }
1589 
1590 static int setup_clone(struct request *clone, struct request *rq,
1591 		       struct dm_rq_target_io *tio)
1592 {
1593 	int r;
1594 
1595 	if (dm_rq_is_flush_request(rq)) {
1596 		blk_rq_init(NULL, clone);
1597 		clone->cmd_type = REQ_TYPE_FS;
1598 		clone->cmd_flags |= (REQ_HARDBARRIER | WRITE);
1599 	} else {
1600 		r = blk_rq_prep_clone(clone, rq, tio->md->bs, GFP_ATOMIC,
1601 				      dm_rq_bio_constructor, tio);
1602 		if (r)
1603 			return r;
1604 
1605 		clone->cmd = rq->cmd;
1606 		clone->cmd_len = rq->cmd_len;
1607 		clone->sense = rq->sense;
1608 		clone->buffer = rq->buffer;
1609 	}
1610 
1611 	clone->end_io = end_clone_request;
1612 	clone->end_io_data = tio;
1613 
1614 	return 0;
1615 }
1616 
1617 static struct request *clone_rq(struct request *rq, struct mapped_device *md,
1618 				gfp_t gfp_mask)
1619 {
1620 	struct request *clone;
1621 	struct dm_rq_target_io *tio;
1622 
1623 	tio = alloc_rq_tio(md, gfp_mask);
1624 	if (!tio)
1625 		return NULL;
1626 
1627 	tio->md = md;
1628 	tio->ti = NULL;
1629 	tio->orig = rq;
1630 	tio->error = 0;
1631 	memset(&tio->info, 0, sizeof(tio->info));
1632 
1633 	clone = &tio->clone;
1634 	if (setup_clone(clone, rq, tio)) {
1635 		/* -ENOMEM */
1636 		free_rq_tio(tio);
1637 		return NULL;
1638 	}
1639 
1640 	return clone;
1641 }
1642 
1643 /*
1644  * Called with the queue lock held.
1645  */
1646 static int dm_prep_fn(struct request_queue *q, struct request *rq)
1647 {
1648 	struct mapped_device *md = q->queuedata;
1649 	struct request *clone;
1650 
1651 	if (unlikely(dm_rq_is_flush_request(rq)))
1652 		return BLKPREP_OK;
1653 
1654 	if (unlikely(rq->special)) {
1655 		DMWARN("Already has something in rq->special.");
1656 		return BLKPREP_KILL;
1657 	}
1658 
1659 	clone = clone_rq(rq, md, GFP_ATOMIC);
1660 	if (!clone)
1661 		return BLKPREP_DEFER;
1662 
1663 	rq->special = clone;
1664 	rq->cmd_flags |= REQ_DONTPREP;
1665 
1666 	return BLKPREP_OK;
1667 }
1668 
1669 /*
1670  * Returns:
1671  * 0  : the request has been processed (not requeued)
1672  * !0 : the request has been requeued
1673  */
1674 static int map_request(struct dm_target *ti, struct request *clone,
1675 		       struct mapped_device *md)
1676 {
1677 	int r, requeued = 0;
1678 	struct dm_rq_target_io *tio = clone->end_io_data;
1679 
1680 	/*
1681 	 * Hold the md reference here for the in-flight I/O.
1682 	 * We can't rely on the reference count by device opener,
1683 	 * because the device may be closed during the request completion
1684 	 * when all bios are completed.
1685 	 * See the comment in rq_completed() too.
1686 	 */
1687 	dm_get(md);
1688 
1689 	tio->ti = ti;
1690 	r = ti->type->map_rq(ti, clone, &tio->info);
1691 	switch (r) {
1692 	case DM_MAPIO_SUBMITTED:
1693 		/* The target has taken the I/O to submit by itself later */
1694 		break;
1695 	case DM_MAPIO_REMAPPED:
1696 		/* The target has remapped the I/O so dispatch it */
1697 		trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
1698 				     blk_rq_pos(tio->orig));
1699 		dm_dispatch_request(clone);
1700 		break;
1701 	case DM_MAPIO_REQUEUE:
1702 		/* The target wants to requeue the I/O */
1703 		dm_requeue_unmapped_request(clone);
1704 		requeued = 1;
1705 		break;
1706 	default:
1707 		if (r > 0) {
1708 			DMWARN("unimplemented target map return value: %d", r);
1709 			BUG();
1710 		}
1711 
1712 		/* The target wants to complete the I/O */
1713 		dm_kill_unmapped_request(clone, r);
1714 		break;
1715 	}
1716 
1717 	return requeued;
1718 }
1719 
1720 /*
1721  * q->request_fn for request-based dm.
1722  * Called with the queue lock held.
1723  */
1724 static void dm_request_fn(struct request_queue *q)
1725 {
1726 	struct mapped_device *md = q->queuedata;
1727 	struct dm_table *map = dm_get_live_table(md);
1728 	struct dm_target *ti;
1729 	struct request *rq, *clone;
1730 
1731 	/*
1732 	 * For suspend, check blk_queue_stopped() and increment
1733 	 * ->pending within a single queue_lock not to increment the
1734 	 * number of in-flight I/Os after the queue is stopped in
1735 	 * dm_suspend().
1736 	 */
1737 	while (!blk_queue_plugged(q) && !blk_queue_stopped(q)) {
1738 		rq = blk_peek_request(q);
1739 		if (!rq)
1740 			goto plug_and_out;
1741 
1742 		if (unlikely(dm_rq_is_flush_request(rq))) {
1743 			BUG_ON(md->flush_request);
1744 			md->flush_request = rq;
1745 			blk_start_request(rq);
1746 			queue_work(md->wq, &md->barrier_work);
1747 			goto out;
1748 		}
1749 
1750 		ti = dm_table_find_target(map, blk_rq_pos(rq));
1751 		if (ti->type->busy && ti->type->busy(ti))
1752 			goto plug_and_out;
1753 
1754 		blk_start_request(rq);
1755 		clone = rq->special;
1756 		atomic_inc(&md->pending[rq_data_dir(clone)]);
1757 
1758 		spin_unlock(q->queue_lock);
1759 		if (map_request(ti, clone, md))
1760 			goto requeued;
1761 
1762 		spin_lock_irq(q->queue_lock);
1763 	}
1764 
1765 	goto out;
1766 
1767 requeued:
1768 	spin_lock_irq(q->queue_lock);
1769 
1770 plug_and_out:
1771 	if (!elv_queue_empty(q))
1772 		/* Some requests still remain, retry later */
1773 		blk_plug_device(q);
1774 
1775 out:
1776 	dm_table_put(map);
1777 
1778 	return;
1779 }
1780 
1781 int dm_underlying_device_busy(struct request_queue *q)
1782 {
1783 	return blk_lld_busy(q);
1784 }
1785 EXPORT_SYMBOL_GPL(dm_underlying_device_busy);
1786 
1787 static int dm_lld_busy(struct request_queue *q)
1788 {
1789 	int r;
1790 	struct mapped_device *md = q->queuedata;
1791 	struct dm_table *map = dm_get_live_table(md);
1792 
1793 	if (!map || test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))
1794 		r = 1;
1795 	else
1796 		r = dm_table_any_busy_target(map);
1797 
1798 	dm_table_put(map);
1799 
1800 	return r;
1801 }
1802 
1803 static void dm_unplug_all(struct request_queue *q)
1804 {
1805 	struct mapped_device *md = q->queuedata;
1806 	struct dm_table *map = dm_get_live_table(md);
1807 
1808 	if (map) {
1809 		if (dm_request_based(md))
1810 			generic_unplug_device(q);
1811 
1812 		dm_table_unplug_all(map);
1813 		dm_table_put(map);
1814 	}
1815 }
1816 
1817 static int dm_any_congested(void *congested_data, int bdi_bits)
1818 {
1819 	int r = bdi_bits;
1820 	struct mapped_device *md = congested_data;
1821 	struct dm_table *map;
1822 
1823 	if (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
1824 		map = dm_get_live_table(md);
1825 		if (map) {
1826 			/*
1827 			 * Request-based dm cares about only own queue for
1828 			 * the query about congestion status of request_queue
1829 			 */
1830 			if (dm_request_based(md))
1831 				r = md->queue->backing_dev_info.state &
1832 				    bdi_bits;
1833 			else
1834 				r = dm_table_any_congested(map, bdi_bits);
1835 
1836 			dm_table_put(map);
1837 		}
1838 	}
1839 
1840 	return r;
1841 }
1842 
1843 /*-----------------------------------------------------------------
1844  * An IDR is used to keep track of allocated minor numbers.
1845  *---------------------------------------------------------------*/
1846 static DEFINE_IDR(_minor_idr);
1847 
1848 static void free_minor(int minor)
1849 {
1850 	spin_lock(&_minor_lock);
1851 	idr_remove(&_minor_idr, minor);
1852 	spin_unlock(&_minor_lock);
1853 }
1854 
1855 /*
1856  * See if the device with a specific minor # is free.
1857  */
1858 static int specific_minor(int minor)
1859 {
1860 	int r, m;
1861 
1862 	if (minor >= (1 << MINORBITS))
1863 		return -EINVAL;
1864 
1865 	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
1866 	if (!r)
1867 		return -ENOMEM;
1868 
1869 	spin_lock(&_minor_lock);
1870 
1871 	if (idr_find(&_minor_idr, minor)) {
1872 		r = -EBUSY;
1873 		goto out;
1874 	}
1875 
1876 	r = idr_get_new_above(&_minor_idr, MINOR_ALLOCED, minor, &m);
1877 	if (r)
1878 		goto out;
1879 
1880 	if (m != minor) {
1881 		idr_remove(&_minor_idr, m);
1882 		r = -EBUSY;
1883 		goto out;
1884 	}
1885 
1886 out:
1887 	spin_unlock(&_minor_lock);
1888 	return r;
1889 }
1890 
1891 static int next_free_minor(int *minor)
1892 {
1893 	int r, m;
1894 
1895 	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
1896 	if (!r)
1897 		return -ENOMEM;
1898 
1899 	spin_lock(&_minor_lock);
1900 
1901 	r = idr_get_new(&_minor_idr, MINOR_ALLOCED, &m);
1902 	if (r)
1903 		goto out;
1904 
1905 	if (m >= (1 << MINORBITS)) {
1906 		idr_remove(&_minor_idr, m);
1907 		r = -ENOSPC;
1908 		goto out;
1909 	}
1910 
1911 	*minor = m;
1912 
1913 out:
1914 	spin_unlock(&_minor_lock);
1915 	return r;
1916 }
1917 
1918 static const struct block_device_operations dm_blk_dops;
1919 
1920 static void dm_wq_work(struct work_struct *work);
1921 static void dm_rq_barrier_work(struct work_struct *work);
1922 
1923 static void dm_init_md_queue(struct mapped_device *md)
1924 {
1925 	/*
1926 	 * Request-based dm devices cannot be stacked on top of bio-based dm
1927 	 * devices.  The type of this dm device has not been decided yet.
1928 	 * The type is decided at the first table loading time.
1929 	 * To prevent problematic device stacking, clear the queue flag
1930 	 * for request stacking support until then.
1931 	 *
1932 	 * This queue is new, so no concurrency on the queue_flags.
1933 	 */
1934 	queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue);
1935 
1936 	md->queue->queuedata = md;
1937 	md->queue->backing_dev_info.congested_fn = dm_any_congested;
1938 	md->queue->backing_dev_info.congested_data = md;
1939 	blk_queue_make_request(md->queue, dm_request);
1940 	blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
1941 	md->queue->unplug_fn = dm_unplug_all;
1942 	blk_queue_merge_bvec(md->queue, dm_merge_bvec);
1943 }
1944 
1945 /*
1946  * Allocate and initialise a blank device with a given minor.
1947  */
1948 static struct mapped_device *alloc_dev(int minor)
1949 {
1950 	int r;
1951 	struct mapped_device *md = kzalloc(sizeof(*md), GFP_KERNEL);
1952 	void *old_md;
1953 
1954 	if (!md) {
1955 		DMWARN("unable to allocate device, out of memory.");
1956 		return NULL;
1957 	}
1958 
1959 	if (!try_module_get(THIS_MODULE))
1960 		goto bad_module_get;
1961 
1962 	/* get a minor number for the dev */
1963 	if (minor == DM_ANY_MINOR)
1964 		r = next_free_minor(&minor);
1965 	else
1966 		r = specific_minor(minor);
1967 	if (r < 0)
1968 		goto bad_minor;
1969 
1970 	md->type = DM_TYPE_NONE;
1971 	init_rwsem(&md->io_lock);
1972 	mutex_init(&md->suspend_lock);
1973 	mutex_init(&md->type_lock);
1974 	spin_lock_init(&md->deferred_lock);
1975 	spin_lock_init(&md->barrier_error_lock);
1976 	rwlock_init(&md->map_lock);
1977 	atomic_set(&md->holders, 1);
1978 	atomic_set(&md->open_count, 0);
1979 	atomic_set(&md->event_nr, 0);
1980 	atomic_set(&md->uevent_seq, 0);
1981 	INIT_LIST_HEAD(&md->uevent_list);
1982 	spin_lock_init(&md->uevent_lock);
1983 
1984 	md->queue = blk_alloc_queue(GFP_KERNEL);
1985 	if (!md->queue)
1986 		goto bad_queue;
1987 
1988 	dm_init_md_queue(md);
1989 
1990 	md->disk = alloc_disk(1);
1991 	if (!md->disk)
1992 		goto bad_disk;
1993 
1994 	atomic_set(&md->pending[0], 0);
1995 	atomic_set(&md->pending[1], 0);
1996 	init_waitqueue_head(&md->wait);
1997 	INIT_WORK(&md->work, dm_wq_work);
1998 	INIT_WORK(&md->barrier_work, dm_rq_barrier_work);
1999 	init_waitqueue_head(&md->eventq);
2000 
2001 	md->disk->major = _major;
2002 	md->disk->first_minor = minor;
2003 	md->disk->fops = &dm_blk_dops;
2004 	md->disk->queue = md->queue;
2005 	md->disk->private_data = md;
2006 	sprintf(md->disk->disk_name, "dm-%d", minor);
2007 	add_disk(md->disk);
2008 	format_dev_t(md->name, MKDEV(_major, minor));
2009 
2010 	md->wq = create_singlethread_workqueue("kdmflush");
2011 	if (!md->wq)
2012 		goto bad_thread;
2013 
2014 	md->bdev = bdget_disk(md->disk, 0);
2015 	if (!md->bdev)
2016 		goto bad_bdev;
2017 
2018 	/* Populate the mapping, nobody knows we exist yet */
2019 	spin_lock(&_minor_lock);
2020 	old_md = idr_replace(&_minor_idr, md, minor);
2021 	spin_unlock(&_minor_lock);
2022 
2023 	BUG_ON(old_md != MINOR_ALLOCED);
2024 
2025 	return md;
2026 
2027 bad_bdev:
2028 	destroy_workqueue(md->wq);
2029 bad_thread:
2030 	del_gendisk(md->disk);
2031 	put_disk(md->disk);
2032 bad_disk:
2033 	blk_cleanup_queue(md->queue);
2034 bad_queue:
2035 	free_minor(minor);
2036 bad_minor:
2037 	module_put(THIS_MODULE);
2038 bad_module_get:
2039 	kfree(md);
2040 	return NULL;
2041 }
2042 
2043 static void unlock_fs(struct mapped_device *md);
2044 
2045 static void free_dev(struct mapped_device *md)
2046 {
2047 	int minor = MINOR(disk_devt(md->disk));
2048 
2049 	unlock_fs(md);
2050 	bdput(md->bdev);
2051 	destroy_workqueue(md->wq);
2052 	if (md->tio_pool)
2053 		mempool_destroy(md->tio_pool);
2054 	if (md->io_pool)
2055 		mempool_destroy(md->io_pool);
2056 	if (md->bs)
2057 		bioset_free(md->bs);
2058 	blk_integrity_unregister(md->disk);
2059 	del_gendisk(md->disk);
2060 	free_minor(minor);
2061 
2062 	spin_lock(&_minor_lock);
2063 	md->disk->private_data = NULL;
2064 	spin_unlock(&_minor_lock);
2065 
2066 	put_disk(md->disk);
2067 	blk_cleanup_queue(md->queue);
2068 	module_put(THIS_MODULE);
2069 	kfree(md);
2070 }
2071 
2072 static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
2073 {
2074 	struct dm_md_mempools *p;
2075 
2076 	if (md->io_pool && md->tio_pool && md->bs)
2077 		/* the md already has necessary mempools */
2078 		goto out;
2079 
2080 	p = dm_table_get_md_mempools(t);
2081 	BUG_ON(!p || md->io_pool || md->tio_pool || md->bs);
2082 
2083 	md->io_pool = p->io_pool;
2084 	p->io_pool = NULL;
2085 	md->tio_pool = p->tio_pool;
2086 	p->tio_pool = NULL;
2087 	md->bs = p->bs;
2088 	p->bs = NULL;
2089 
2090 out:
2091 	/* mempool bind completed, now no need any mempools in the table */
2092 	dm_table_free_md_mempools(t);
2093 }
2094 
2095 /*
2096  * Bind a table to the device.
2097  */
2098 static void event_callback(void *context)
2099 {
2100 	unsigned long flags;
2101 	LIST_HEAD(uevents);
2102 	struct mapped_device *md = (struct mapped_device *) context;
2103 
2104 	spin_lock_irqsave(&md->uevent_lock, flags);
2105 	list_splice_init(&md->uevent_list, &uevents);
2106 	spin_unlock_irqrestore(&md->uevent_lock, flags);
2107 
2108 	dm_send_uevents(&uevents, &disk_to_dev(md->disk)->kobj);
2109 
2110 	atomic_inc(&md->event_nr);
2111 	wake_up(&md->eventq);
2112 }
2113 
2114 static void __set_size(struct mapped_device *md, sector_t size)
2115 {
2116 	set_capacity(md->disk, size);
2117 
2118 	mutex_lock(&md->bdev->bd_inode->i_mutex);
2119 	i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
2120 	mutex_unlock(&md->bdev->bd_inode->i_mutex);
2121 }
2122 
2123 /*
2124  * Returns old map, which caller must destroy.
2125  */
2126 static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
2127 			       struct queue_limits *limits)
2128 {
2129 	struct dm_table *old_map;
2130 	struct request_queue *q = md->queue;
2131 	sector_t size;
2132 	unsigned long flags;
2133 
2134 	size = dm_table_get_size(t);
2135 
2136 	/*
2137 	 * Wipe any geometry if the size of the table changed.
2138 	 */
2139 	if (size != get_capacity(md->disk))
2140 		memset(&md->geometry, 0, sizeof(md->geometry));
2141 
2142 	__set_size(md, size);
2143 
2144 	dm_table_event_callback(t, event_callback, md);
2145 
2146 	/*
2147 	 * The queue hasn't been stopped yet, if the old table type wasn't
2148 	 * for request-based during suspension.  So stop it to prevent
2149 	 * I/O mapping before resume.
2150 	 * This must be done before setting the queue restrictions,
2151 	 * because request-based dm may be run just after the setting.
2152 	 */
2153 	if (dm_table_request_based(t) && !blk_queue_stopped(q))
2154 		stop_queue(q);
2155 
2156 	__bind_mempools(md, t);
2157 
2158 	write_lock_irqsave(&md->map_lock, flags);
2159 	old_map = md->map;
2160 	md->map = t;
2161 	dm_table_set_restrictions(t, q, limits);
2162 	write_unlock_irqrestore(&md->map_lock, flags);
2163 
2164 	return old_map;
2165 }
2166 
2167 /*
2168  * Returns unbound table for the caller to free.
2169  */
2170 static struct dm_table *__unbind(struct mapped_device *md)
2171 {
2172 	struct dm_table *map = md->map;
2173 	unsigned long flags;
2174 
2175 	if (!map)
2176 		return NULL;
2177 
2178 	dm_table_event_callback(map, NULL, NULL);
2179 	write_lock_irqsave(&md->map_lock, flags);
2180 	md->map = NULL;
2181 	write_unlock_irqrestore(&md->map_lock, flags);
2182 
2183 	return map;
2184 }
2185 
2186 /*
2187  * Constructor for a new device.
2188  */
2189 int dm_create(int minor, struct mapped_device **result)
2190 {
2191 	struct mapped_device *md;
2192 
2193 	md = alloc_dev(minor);
2194 	if (!md)
2195 		return -ENXIO;
2196 
2197 	dm_sysfs_init(md);
2198 
2199 	*result = md;
2200 	return 0;
2201 }
2202 
2203 /*
2204  * Functions to manage md->type.
2205  * All are required to hold md->type_lock.
2206  */
2207 void dm_lock_md_type(struct mapped_device *md)
2208 {
2209 	mutex_lock(&md->type_lock);
2210 }
2211 
2212 void dm_unlock_md_type(struct mapped_device *md)
2213 {
2214 	mutex_unlock(&md->type_lock);
2215 }
2216 
2217 void dm_set_md_type(struct mapped_device *md, unsigned type)
2218 {
2219 	md->type = type;
2220 }
2221 
2222 unsigned dm_get_md_type(struct mapped_device *md)
2223 {
2224 	return md->type;
2225 }
2226 
2227 /*
2228  * Fully initialize a request-based queue (->elevator, ->request_fn, etc).
2229  */
2230 static int dm_init_request_based_queue(struct mapped_device *md)
2231 {
2232 	struct request_queue *q = NULL;
2233 
2234 	if (md->queue->elevator)
2235 		return 1;
2236 
2237 	/* Fully initialize the queue */
2238 	q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL);
2239 	if (!q)
2240 		return 0;
2241 
2242 	md->queue = q;
2243 	md->saved_make_request_fn = md->queue->make_request_fn;
2244 	dm_init_md_queue(md);
2245 	blk_queue_softirq_done(md->queue, dm_softirq_done);
2246 	blk_queue_prep_rq(md->queue, dm_prep_fn);
2247 	blk_queue_lld_busy(md->queue, dm_lld_busy);
2248 	blk_queue_ordered(md->queue, QUEUE_ORDERED_DRAIN_FLUSH);
2249 
2250 	elv_register_queue(md->queue);
2251 
2252 	return 1;
2253 }
2254 
2255 /*
2256  * Setup the DM device's queue based on md's type
2257  */
2258 int dm_setup_md_queue(struct mapped_device *md)
2259 {
2260 	if ((dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) &&
2261 	    !dm_init_request_based_queue(md)) {
2262 		DMWARN("Cannot initialize queue for request-based mapped device");
2263 		return -EINVAL;
2264 	}
2265 
2266 	return 0;
2267 }
2268 
2269 static struct mapped_device *dm_find_md(dev_t dev)
2270 {
2271 	struct mapped_device *md;
2272 	unsigned minor = MINOR(dev);
2273 
2274 	if (MAJOR(dev) != _major || minor >= (1 << MINORBITS))
2275 		return NULL;
2276 
2277 	spin_lock(&_minor_lock);
2278 
2279 	md = idr_find(&_minor_idr, minor);
2280 	if (md && (md == MINOR_ALLOCED ||
2281 		   (MINOR(disk_devt(dm_disk(md))) != minor) ||
2282 		   dm_deleting_md(md) ||
2283 		   test_bit(DMF_FREEING, &md->flags))) {
2284 		md = NULL;
2285 		goto out;
2286 	}
2287 
2288 out:
2289 	spin_unlock(&_minor_lock);
2290 
2291 	return md;
2292 }
2293 
2294 struct mapped_device *dm_get_md(dev_t dev)
2295 {
2296 	struct mapped_device *md = dm_find_md(dev);
2297 
2298 	if (md)
2299 		dm_get(md);
2300 
2301 	return md;
2302 }
2303 
2304 void *dm_get_mdptr(struct mapped_device *md)
2305 {
2306 	return md->interface_ptr;
2307 }
2308 
2309 void dm_set_mdptr(struct mapped_device *md, void *ptr)
2310 {
2311 	md->interface_ptr = ptr;
2312 }
2313 
2314 void dm_get(struct mapped_device *md)
2315 {
2316 	atomic_inc(&md->holders);
2317 	BUG_ON(test_bit(DMF_FREEING, &md->flags));
2318 }
2319 
2320 const char *dm_device_name(struct mapped_device *md)
2321 {
2322 	return md->name;
2323 }
2324 EXPORT_SYMBOL_GPL(dm_device_name);
2325 
2326 static void __dm_destroy(struct mapped_device *md, bool wait)
2327 {
2328 	struct dm_table *map;
2329 
2330 	might_sleep();
2331 
2332 	spin_lock(&_minor_lock);
2333 	map = dm_get_live_table(md);
2334 	idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md))));
2335 	set_bit(DMF_FREEING, &md->flags);
2336 	spin_unlock(&_minor_lock);
2337 
2338 	if (!dm_suspended_md(md)) {
2339 		dm_table_presuspend_targets(map);
2340 		dm_table_postsuspend_targets(map);
2341 	}
2342 
2343 	/*
2344 	 * Rare, but there may be I/O requests still going to complete,
2345 	 * for example.  Wait for all references to disappear.
2346 	 * No one should increment the reference count of the mapped_device,
2347 	 * after the mapped_device state becomes DMF_FREEING.
2348 	 */
2349 	if (wait)
2350 		while (atomic_read(&md->holders))
2351 			msleep(1);
2352 	else if (atomic_read(&md->holders))
2353 		DMWARN("%s: Forcibly removing mapped_device still in use! (%d users)",
2354 		       dm_device_name(md), atomic_read(&md->holders));
2355 
2356 	dm_sysfs_exit(md);
2357 	dm_table_put(map);
2358 	dm_table_destroy(__unbind(md));
2359 	free_dev(md);
2360 }
2361 
2362 void dm_destroy(struct mapped_device *md)
2363 {
2364 	__dm_destroy(md, true);
2365 }
2366 
2367 void dm_destroy_immediate(struct mapped_device *md)
2368 {
2369 	__dm_destroy(md, false);
2370 }
2371 
2372 void dm_put(struct mapped_device *md)
2373 {
2374 	atomic_dec(&md->holders);
2375 }
2376 EXPORT_SYMBOL_GPL(dm_put);
2377 
2378 static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
2379 {
2380 	int r = 0;
2381 	DECLARE_WAITQUEUE(wait, current);
2382 
2383 	dm_unplug_all(md->queue);
2384 
2385 	add_wait_queue(&md->wait, &wait);
2386 
2387 	while (1) {
2388 		set_current_state(interruptible);
2389 
2390 		smp_mb();
2391 		if (!md_in_flight(md))
2392 			break;
2393 
2394 		if (interruptible == TASK_INTERRUPTIBLE &&
2395 		    signal_pending(current)) {
2396 			r = -EINTR;
2397 			break;
2398 		}
2399 
2400 		io_schedule();
2401 	}
2402 	set_current_state(TASK_RUNNING);
2403 
2404 	remove_wait_queue(&md->wait, &wait);
2405 
2406 	return r;
2407 }
2408 
2409 static void dm_flush(struct mapped_device *md)
2410 {
2411 	dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
2412 
2413 	bio_init(&md->barrier_bio);
2414 	md->barrier_bio.bi_bdev = md->bdev;
2415 	md->barrier_bio.bi_rw = WRITE_BARRIER;
2416 	__split_and_process_bio(md, &md->barrier_bio);
2417 
2418 	dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
2419 }
2420 
2421 static void process_barrier(struct mapped_device *md, struct bio *bio)
2422 {
2423 	md->barrier_error = 0;
2424 
2425 	dm_flush(md);
2426 
2427 	if (!bio_empty_barrier(bio)) {
2428 		__split_and_process_bio(md, bio);
2429 		/*
2430 		 * If the request isn't supported, don't waste time with
2431 		 * the second flush.
2432 		 */
2433 		if (md->barrier_error != -EOPNOTSUPP)
2434 			dm_flush(md);
2435 	}
2436 
2437 	if (md->barrier_error != DM_ENDIO_REQUEUE)
2438 		bio_endio(bio, md->barrier_error);
2439 	else {
2440 		spin_lock_irq(&md->deferred_lock);
2441 		bio_list_add_head(&md->deferred, bio);
2442 		spin_unlock_irq(&md->deferred_lock);
2443 	}
2444 }
2445 
2446 /*
2447  * Process the deferred bios
2448  */
2449 static void dm_wq_work(struct work_struct *work)
2450 {
2451 	struct mapped_device *md = container_of(work, struct mapped_device,
2452 						work);
2453 	struct bio *c;
2454 
2455 	down_write(&md->io_lock);
2456 
2457 	while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
2458 		spin_lock_irq(&md->deferred_lock);
2459 		c = bio_list_pop(&md->deferred);
2460 		spin_unlock_irq(&md->deferred_lock);
2461 
2462 		if (!c) {
2463 			clear_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags);
2464 			break;
2465 		}
2466 
2467 		up_write(&md->io_lock);
2468 
2469 		if (dm_request_based(md))
2470 			generic_make_request(c);
2471 		else {
2472 			if (c->bi_rw & REQ_HARDBARRIER)
2473 				process_barrier(md, c);
2474 			else
2475 				__split_and_process_bio(md, c);
2476 		}
2477 
2478 		down_write(&md->io_lock);
2479 	}
2480 
2481 	up_write(&md->io_lock);
2482 }
2483 
2484 static void dm_queue_flush(struct mapped_device *md)
2485 {
2486 	clear_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
2487 	smp_mb__after_clear_bit();
2488 	queue_work(md->wq, &md->work);
2489 }
2490 
2491 static void dm_rq_set_target_request_nr(struct request *clone, unsigned request_nr)
2492 {
2493 	struct dm_rq_target_io *tio = clone->end_io_data;
2494 
2495 	tio->info.target_request_nr = request_nr;
2496 }
2497 
2498 /* Issue barrier requests to targets and wait for their completion. */
2499 static int dm_rq_barrier(struct mapped_device *md)
2500 {
2501 	int i, j;
2502 	struct dm_table *map = dm_get_live_table(md);
2503 	unsigned num_targets = dm_table_get_num_targets(map);
2504 	struct dm_target *ti;
2505 	struct request *clone;
2506 
2507 	md->barrier_error = 0;
2508 
2509 	for (i = 0; i < num_targets; i++) {
2510 		ti = dm_table_get_target(map, i);
2511 		for (j = 0; j < ti->num_flush_requests; j++) {
2512 			clone = clone_rq(md->flush_request, md, GFP_NOIO);
2513 			dm_rq_set_target_request_nr(clone, j);
2514 			atomic_inc(&md->pending[rq_data_dir(clone)]);
2515 			map_request(ti, clone, md);
2516 		}
2517 	}
2518 
2519 	dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
2520 	dm_table_put(map);
2521 
2522 	return md->barrier_error;
2523 }
2524 
2525 static void dm_rq_barrier_work(struct work_struct *work)
2526 {
2527 	int error;
2528 	struct mapped_device *md = container_of(work, struct mapped_device,
2529 						barrier_work);
2530 	struct request_queue *q = md->queue;
2531 	struct request *rq;
2532 	unsigned long flags;
2533 
2534 	/*
2535 	 * Hold the md reference here and leave it at the last part so that
2536 	 * the md can't be deleted by device opener when the barrier request
2537 	 * completes.
2538 	 */
2539 	dm_get(md);
2540 
2541 	error = dm_rq_barrier(md);
2542 
2543 	rq = md->flush_request;
2544 	md->flush_request = NULL;
2545 
2546 	if (error == DM_ENDIO_REQUEUE) {
2547 		spin_lock_irqsave(q->queue_lock, flags);
2548 		blk_requeue_request(q, rq);
2549 		spin_unlock_irqrestore(q->queue_lock, flags);
2550 	} else
2551 		blk_end_request_all(rq, error);
2552 
2553 	blk_run_queue(q);
2554 
2555 	dm_put(md);
2556 }
2557 
2558 /*
2559  * Swap in a new table, returning the old one for the caller to destroy.
2560  */
2561 struct dm_table *dm_swap_table(struct mapped_device *md, struct dm_table *table)
2562 {
2563 	struct dm_table *map = ERR_PTR(-EINVAL);
2564 	struct queue_limits limits;
2565 	int r;
2566 
2567 	mutex_lock(&md->suspend_lock);
2568 
2569 	/* device must be suspended */
2570 	if (!dm_suspended_md(md))
2571 		goto out;
2572 
2573 	r = dm_calculate_queue_limits(table, &limits);
2574 	if (r) {
2575 		map = ERR_PTR(r);
2576 		goto out;
2577 	}
2578 
2579 	map = __bind(md, table, &limits);
2580 
2581 out:
2582 	mutex_unlock(&md->suspend_lock);
2583 	return map;
2584 }
2585 
2586 /*
2587  * Functions to lock and unlock any filesystem running on the
2588  * device.
2589  */
2590 static int lock_fs(struct mapped_device *md)
2591 {
2592 	int r;
2593 
2594 	WARN_ON(md->frozen_sb);
2595 
2596 	md->frozen_sb = freeze_bdev(md->bdev);
2597 	if (IS_ERR(md->frozen_sb)) {
2598 		r = PTR_ERR(md->frozen_sb);
2599 		md->frozen_sb = NULL;
2600 		return r;
2601 	}
2602 
2603 	set_bit(DMF_FROZEN, &md->flags);
2604 
2605 	return 0;
2606 }
2607 
2608 static void unlock_fs(struct mapped_device *md)
2609 {
2610 	if (!test_bit(DMF_FROZEN, &md->flags))
2611 		return;
2612 
2613 	thaw_bdev(md->bdev, md->frozen_sb);
2614 	md->frozen_sb = NULL;
2615 	clear_bit(DMF_FROZEN, &md->flags);
2616 }
2617 
2618 /*
2619  * We need to be able to change a mapping table under a mounted
2620  * filesystem.  For example we might want to move some data in
2621  * the background.  Before the table can be swapped with
2622  * dm_bind_table, dm_suspend must be called to flush any in
2623  * flight bios and ensure that any further io gets deferred.
2624  */
2625 /*
2626  * Suspend mechanism in request-based dm.
2627  *
2628  * 1. Flush all I/Os by lock_fs() if needed.
2629  * 2. Stop dispatching any I/O by stopping the request_queue.
2630  * 3. Wait for all in-flight I/Os to be completed or requeued.
2631  *
2632  * To abort suspend, start the request_queue.
2633  */
2634 int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
2635 {
2636 	struct dm_table *map = NULL;
2637 	int r = 0;
2638 	int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0;
2639 	int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0;
2640 
2641 	mutex_lock(&md->suspend_lock);
2642 
2643 	if (dm_suspended_md(md)) {
2644 		r = -EINVAL;
2645 		goto out_unlock;
2646 	}
2647 
2648 	map = dm_get_live_table(md);
2649 
2650 	/*
2651 	 * DMF_NOFLUSH_SUSPENDING must be set before presuspend.
2652 	 * This flag is cleared before dm_suspend returns.
2653 	 */
2654 	if (noflush)
2655 		set_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
2656 
2657 	/* This does not get reverted if there's an error later. */
2658 	dm_table_presuspend_targets(map);
2659 
2660 	/*
2661 	 * Flush I/O to the device.
2662 	 * Any I/O submitted after lock_fs() may not be flushed.
2663 	 * noflush takes precedence over do_lockfs.
2664 	 * (lock_fs() flushes I/Os and waits for them to complete.)
2665 	 */
2666 	if (!noflush && do_lockfs) {
2667 		r = lock_fs(md);
2668 		if (r)
2669 			goto out;
2670 	}
2671 
2672 	/*
2673 	 * Here we must make sure that no processes are submitting requests
2674 	 * to target drivers i.e. no one may be executing
2675 	 * __split_and_process_bio. This is called from dm_request and
2676 	 * dm_wq_work.
2677 	 *
2678 	 * To get all processes out of __split_and_process_bio in dm_request,
2679 	 * we take the write lock. To prevent any process from reentering
2680 	 * __split_and_process_bio from dm_request, we set
2681 	 * DMF_QUEUE_IO_TO_THREAD.
2682 	 *
2683 	 * To quiesce the thread (dm_wq_work), we set DMF_BLOCK_IO_FOR_SUSPEND
2684 	 * and call flush_workqueue(md->wq). flush_workqueue will wait until
2685 	 * dm_wq_work exits and DMF_BLOCK_IO_FOR_SUSPEND will prevent any
2686 	 * further calls to __split_and_process_bio from dm_wq_work.
2687 	 */
2688 	down_write(&md->io_lock);
2689 	set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
2690 	set_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags);
2691 	up_write(&md->io_lock);
2692 
2693 	/*
2694 	 * Request-based dm uses md->wq for barrier (dm_rq_barrier_work) which
2695 	 * can be kicked until md->queue is stopped.  So stop md->queue before
2696 	 * flushing md->wq.
2697 	 */
2698 	if (dm_request_based(md))
2699 		stop_queue(md->queue);
2700 
2701 	flush_workqueue(md->wq);
2702 
2703 	/*
2704 	 * At this point no more requests are entering target request routines.
2705 	 * We call dm_wait_for_completion to wait for all existing requests
2706 	 * to finish.
2707 	 */
2708 	r = dm_wait_for_completion(md, TASK_INTERRUPTIBLE);
2709 
2710 	down_write(&md->io_lock);
2711 	if (noflush)
2712 		clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
2713 	up_write(&md->io_lock);
2714 
2715 	/* were we interrupted ? */
2716 	if (r < 0) {
2717 		dm_queue_flush(md);
2718 
2719 		if (dm_request_based(md))
2720 			start_queue(md->queue);
2721 
2722 		unlock_fs(md);
2723 		goto out; /* pushback list is already flushed, so skip flush */
2724 	}
2725 
2726 	/*
2727 	 * If dm_wait_for_completion returned 0, the device is completely
2728 	 * quiescent now. There is no request-processing activity. All new
2729 	 * requests are being added to md->deferred list.
2730 	 */
2731 
2732 	set_bit(DMF_SUSPENDED, &md->flags);
2733 
2734 	dm_table_postsuspend_targets(map);
2735 
2736 out:
2737 	dm_table_put(map);
2738 
2739 out_unlock:
2740 	mutex_unlock(&md->suspend_lock);
2741 	return r;
2742 }
2743 
2744 int dm_resume(struct mapped_device *md)
2745 {
2746 	int r = -EINVAL;
2747 	struct dm_table *map = NULL;
2748 
2749 	mutex_lock(&md->suspend_lock);
2750 	if (!dm_suspended_md(md))
2751 		goto out;
2752 
2753 	map = dm_get_live_table(md);
2754 	if (!map || !dm_table_get_size(map))
2755 		goto out;
2756 
2757 	r = dm_table_resume_targets(map);
2758 	if (r)
2759 		goto out;
2760 
2761 	dm_queue_flush(md);
2762 
2763 	/*
2764 	 * Flushing deferred I/Os must be done after targets are resumed
2765 	 * so that mapping of targets can work correctly.
2766 	 * Request-based dm is queueing the deferred I/Os in its request_queue.
2767 	 */
2768 	if (dm_request_based(md))
2769 		start_queue(md->queue);
2770 
2771 	unlock_fs(md);
2772 
2773 	clear_bit(DMF_SUSPENDED, &md->flags);
2774 
2775 	dm_table_unplug_all(map);
2776 	r = 0;
2777 out:
2778 	dm_table_put(map);
2779 	mutex_unlock(&md->suspend_lock);
2780 
2781 	return r;
2782 }
2783 
2784 /*-----------------------------------------------------------------
2785  * Event notification.
2786  *---------------------------------------------------------------*/
2787 int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
2788 		       unsigned cookie)
2789 {
2790 	char udev_cookie[DM_COOKIE_LENGTH];
2791 	char *envp[] = { udev_cookie, NULL };
2792 
2793 	if (!cookie)
2794 		return kobject_uevent(&disk_to_dev(md->disk)->kobj, action);
2795 	else {
2796 		snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u",
2797 			 DM_COOKIE_ENV_VAR_NAME, cookie);
2798 		return kobject_uevent_env(&disk_to_dev(md->disk)->kobj,
2799 					  action, envp);
2800 	}
2801 }
2802 
2803 uint32_t dm_next_uevent_seq(struct mapped_device *md)
2804 {
2805 	return atomic_add_return(1, &md->uevent_seq);
2806 }
2807 
2808 uint32_t dm_get_event_nr(struct mapped_device *md)
2809 {
2810 	return atomic_read(&md->event_nr);
2811 }
2812 
2813 int dm_wait_event(struct mapped_device *md, int event_nr)
2814 {
2815 	return wait_event_interruptible(md->eventq,
2816 			(event_nr != atomic_read(&md->event_nr)));
2817 }
2818 
2819 void dm_uevent_add(struct mapped_device *md, struct list_head *elist)
2820 {
2821 	unsigned long flags;
2822 
2823 	spin_lock_irqsave(&md->uevent_lock, flags);
2824 	list_add(elist, &md->uevent_list);
2825 	spin_unlock_irqrestore(&md->uevent_lock, flags);
2826 }
2827 
2828 /*
2829  * The gendisk is only valid as long as you have a reference
2830  * count on 'md'.
2831  */
2832 struct gendisk *dm_disk(struct mapped_device *md)
2833 {
2834 	return md->disk;
2835 }
2836 
2837 struct kobject *dm_kobject(struct mapped_device *md)
2838 {
2839 	return &md->kobj;
2840 }
2841 
2842 /*
2843  * struct mapped_device should not be exported outside of dm.c
2844  * so use this check to verify that kobj is part of md structure
2845  */
2846 struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
2847 {
2848 	struct mapped_device *md;
2849 
2850 	md = container_of(kobj, struct mapped_device, kobj);
2851 	if (&md->kobj != kobj)
2852 		return NULL;
2853 
2854 	if (test_bit(DMF_FREEING, &md->flags) ||
2855 	    dm_deleting_md(md))
2856 		return NULL;
2857 
2858 	dm_get(md);
2859 	return md;
2860 }
2861 
2862 int dm_suspended_md(struct mapped_device *md)
2863 {
2864 	return test_bit(DMF_SUSPENDED, &md->flags);
2865 }
2866 
2867 int dm_suspended(struct dm_target *ti)
2868 {
2869 	return dm_suspended_md(dm_table_get_md(ti->table));
2870 }
2871 EXPORT_SYMBOL_GPL(dm_suspended);
2872 
2873 int dm_noflush_suspending(struct dm_target *ti)
2874 {
2875 	return __noflush_suspending(dm_table_get_md(ti->table));
2876 }
2877 EXPORT_SYMBOL_GPL(dm_noflush_suspending);
2878 
2879 struct dm_md_mempools *dm_alloc_md_mempools(unsigned type)
2880 {
2881 	struct dm_md_mempools *pools = kmalloc(sizeof(*pools), GFP_KERNEL);
2882 
2883 	if (!pools)
2884 		return NULL;
2885 
2886 	pools->io_pool = (type == DM_TYPE_BIO_BASED) ?
2887 			 mempool_create_slab_pool(MIN_IOS, _io_cache) :
2888 			 mempool_create_slab_pool(MIN_IOS, _rq_bio_info_cache);
2889 	if (!pools->io_pool)
2890 		goto free_pools_and_out;
2891 
2892 	pools->tio_pool = (type == DM_TYPE_BIO_BASED) ?
2893 			  mempool_create_slab_pool(MIN_IOS, _tio_cache) :
2894 			  mempool_create_slab_pool(MIN_IOS, _rq_tio_cache);
2895 	if (!pools->tio_pool)
2896 		goto free_io_pool_and_out;
2897 
2898 	pools->bs = (type == DM_TYPE_BIO_BASED) ?
2899 		    bioset_create(16, 0) : bioset_create(MIN_IOS, 0);
2900 	if (!pools->bs)
2901 		goto free_tio_pool_and_out;
2902 
2903 	return pools;
2904 
2905 free_tio_pool_and_out:
2906 	mempool_destroy(pools->tio_pool);
2907 
2908 free_io_pool_and_out:
2909 	mempool_destroy(pools->io_pool);
2910 
2911 free_pools_and_out:
2912 	kfree(pools);
2913 
2914 	return NULL;
2915 }
2916 
2917 void dm_free_md_mempools(struct dm_md_mempools *pools)
2918 {
2919 	if (!pools)
2920 		return;
2921 
2922 	if (pools->io_pool)
2923 		mempool_destroy(pools->io_pool);
2924 
2925 	if (pools->tio_pool)
2926 		mempool_destroy(pools->tio_pool);
2927 
2928 	if (pools->bs)
2929 		bioset_free(pools->bs);
2930 
2931 	kfree(pools);
2932 }
2933 
2934 static const struct block_device_operations dm_blk_dops = {
2935 	.open = dm_blk_open,
2936 	.release = dm_blk_close,
2937 	.ioctl = dm_blk_ioctl,
2938 	.getgeo = dm_blk_getgeo,
2939 	.owner = THIS_MODULE
2940 };
2941 
2942 EXPORT_SYMBOL(dm_get_mapinfo);
2943 
2944 /*
2945  * module hooks
2946  */
2947 module_init(dm_init);
2948 module_exit(dm_exit);
2949 
2950 module_param(major, uint, 0);
2951 MODULE_PARM_DESC(major, "The major number of the device mapper");
2952 MODULE_DESCRIPTION(DM_NAME " driver");
2953 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
2954 MODULE_LICENSE("GPL");
2955