xref: /openbmc/linux/drivers/md/dm.c (revision b34081f1)
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  * For bio-based dm.
54  * One of these is allocated per bio.
55  */
56 struct dm_io {
57 	struct mapped_device *md;
58 	int error;
59 	atomic_t io_count;
60 	struct bio *bio;
61 	unsigned long start_time;
62 	spinlock_t endio_lock;
63 	struct dm_stats_aux stats_aux;
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 - the bio clones we allocate are embedded in these
80  * structs.
81  *
82  * We allocate these with bio_alloc_bioset, using the front_pad parameter when
83  * the bioset is created - this means the bio has to come at the end of the
84  * struct.
85  */
86 struct dm_rq_clone_bio_info {
87 	struct bio *orig;
88 	struct dm_rq_target_io *tio;
89 	struct bio clone;
90 };
91 
92 union map_info *dm_get_mapinfo(struct bio *bio)
93 {
94 	if (bio && bio->bi_private)
95 		return &((struct dm_target_io *)bio->bi_private)->info;
96 	return NULL;
97 }
98 
99 union map_info *dm_get_rq_mapinfo(struct request *rq)
100 {
101 	if (rq && rq->end_io_data)
102 		return &((struct dm_rq_target_io *)rq->end_io_data)->info;
103 	return NULL;
104 }
105 EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo);
106 
107 #define MINOR_ALLOCED ((void *)-1)
108 
109 /*
110  * Bits for the md->flags field.
111  */
112 #define DMF_BLOCK_IO_FOR_SUSPEND 0
113 #define DMF_SUSPENDED 1
114 #define DMF_FROZEN 2
115 #define DMF_FREEING 3
116 #define DMF_DELETING 4
117 #define DMF_NOFLUSH_SUSPENDING 5
118 #define DMF_MERGE_IS_OPTIONAL 6
119 
120 /*
121  * A dummy definition to make RCU happy.
122  * struct dm_table should never be dereferenced in this file.
123  */
124 struct dm_table {
125 	int undefined__;
126 };
127 
128 /*
129  * Work processed by per-device workqueue.
130  */
131 struct mapped_device {
132 	struct srcu_struct io_barrier;
133 	struct mutex suspend_lock;
134 	atomic_t holders;
135 	atomic_t open_count;
136 
137 	/*
138 	 * The current mapping.
139 	 * Use dm_get_live_table{_fast} or take suspend_lock for
140 	 * dereference.
141 	 */
142 	struct dm_table *map;
143 
144 	unsigned long flags;
145 
146 	struct request_queue *queue;
147 	unsigned type;
148 	/* Protect queue and type against concurrent access. */
149 	struct mutex type_lock;
150 
151 	struct target_type *immutable_target_type;
152 
153 	struct gendisk *disk;
154 	char name[16];
155 
156 	void *interface_ptr;
157 
158 	/*
159 	 * A list of ios that arrived while we were suspended.
160 	 */
161 	atomic_t pending[2];
162 	wait_queue_head_t wait;
163 	struct work_struct work;
164 	struct bio_list deferred;
165 	spinlock_t deferred_lock;
166 
167 	/*
168 	 * Processing queue (flush)
169 	 */
170 	struct workqueue_struct *wq;
171 
172 	/*
173 	 * io objects are allocated from here.
174 	 */
175 	mempool_t *io_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 	/* sysfs handle */
198 	struct kobject kobj;
199 
200 	/* zero-length flush that will be cloned and submitted to targets */
201 	struct bio flush_bio;
202 
203 	struct dm_stats stats;
204 };
205 
206 /*
207  * For mempools pre-allocation at the table loading time.
208  */
209 struct dm_md_mempools {
210 	mempool_t *io_pool;
211 	struct bio_set *bs;
212 };
213 
214 #define MIN_IOS 256
215 static struct kmem_cache *_io_cache;
216 static struct kmem_cache *_rq_tio_cache;
217 
218 static int __init local_init(void)
219 {
220 	int r = -ENOMEM;
221 
222 	/* allocate a slab for the dm_ios */
223 	_io_cache = KMEM_CACHE(dm_io, 0);
224 	if (!_io_cache)
225 		return r;
226 
227 	_rq_tio_cache = KMEM_CACHE(dm_rq_target_io, 0);
228 	if (!_rq_tio_cache)
229 		goto out_free_io_cache;
230 
231 	r = dm_uevent_init();
232 	if (r)
233 		goto out_free_rq_tio_cache;
234 
235 	_major = major;
236 	r = register_blkdev(_major, _name);
237 	if (r < 0)
238 		goto out_uevent_exit;
239 
240 	if (!_major)
241 		_major = r;
242 
243 	return 0;
244 
245 out_uevent_exit:
246 	dm_uevent_exit();
247 out_free_rq_tio_cache:
248 	kmem_cache_destroy(_rq_tio_cache);
249 out_free_io_cache:
250 	kmem_cache_destroy(_io_cache);
251 
252 	return r;
253 }
254 
255 static void local_exit(void)
256 {
257 	kmem_cache_destroy(_rq_tio_cache);
258 	kmem_cache_destroy(_io_cache);
259 	unregister_blkdev(_major, _name);
260 	dm_uevent_exit();
261 
262 	_major = 0;
263 
264 	DMINFO("cleaned up");
265 }
266 
267 static int (*_inits[])(void) __initdata = {
268 	local_init,
269 	dm_target_init,
270 	dm_linear_init,
271 	dm_stripe_init,
272 	dm_io_init,
273 	dm_kcopyd_init,
274 	dm_interface_init,
275 	dm_statistics_init,
276 };
277 
278 static void (*_exits[])(void) = {
279 	local_exit,
280 	dm_target_exit,
281 	dm_linear_exit,
282 	dm_stripe_exit,
283 	dm_io_exit,
284 	dm_kcopyd_exit,
285 	dm_interface_exit,
286 	dm_statistics_exit,
287 };
288 
289 static int __init dm_init(void)
290 {
291 	const int count = ARRAY_SIZE(_inits);
292 
293 	int r, i;
294 
295 	for (i = 0; i < count; i++) {
296 		r = _inits[i]();
297 		if (r)
298 			goto bad;
299 	}
300 
301 	return 0;
302 
303       bad:
304 	while (i--)
305 		_exits[i]();
306 
307 	return r;
308 }
309 
310 static void __exit dm_exit(void)
311 {
312 	int i = ARRAY_SIZE(_exits);
313 
314 	while (i--)
315 		_exits[i]();
316 
317 	/*
318 	 * Should be empty by this point.
319 	 */
320 	idr_destroy(&_minor_idr);
321 }
322 
323 /*
324  * Block device functions
325  */
326 int dm_deleting_md(struct mapped_device *md)
327 {
328 	return test_bit(DMF_DELETING, &md->flags);
329 }
330 
331 static int dm_blk_open(struct block_device *bdev, fmode_t mode)
332 {
333 	struct mapped_device *md;
334 
335 	spin_lock(&_minor_lock);
336 
337 	md = bdev->bd_disk->private_data;
338 	if (!md)
339 		goto out;
340 
341 	if (test_bit(DMF_FREEING, &md->flags) ||
342 	    dm_deleting_md(md)) {
343 		md = NULL;
344 		goto out;
345 	}
346 
347 	dm_get(md);
348 	atomic_inc(&md->open_count);
349 
350 out:
351 	spin_unlock(&_minor_lock);
352 
353 	return md ? 0 : -ENXIO;
354 }
355 
356 static void dm_blk_close(struct gendisk *disk, fmode_t mode)
357 {
358 	struct mapped_device *md = disk->private_data;
359 
360 	spin_lock(&_minor_lock);
361 
362 	atomic_dec(&md->open_count);
363 	dm_put(md);
364 
365 	spin_unlock(&_minor_lock);
366 }
367 
368 int dm_open_count(struct mapped_device *md)
369 {
370 	return atomic_read(&md->open_count);
371 }
372 
373 /*
374  * Guarantees nothing is using the device before it's deleted.
375  */
376 int dm_lock_for_deletion(struct mapped_device *md)
377 {
378 	int r = 0;
379 
380 	spin_lock(&_minor_lock);
381 
382 	if (dm_open_count(md))
383 		r = -EBUSY;
384 	else
385 		set_bit(DMF_DELETING, &md->flags);
386 
387 	spin_unlock(&_minor_lock);
388 
389 	return r;
390 }
391 
392 sector_t dm_get_size(struct mapped_device *md)
393 {
394 	return get_capacity(md->disk);
395 }
396 
397 struct dm_stats *dm_get_stats(struct mapped_device *md)
398 {
399 	return &md->stats;
400 }
401 
402 static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
403 {
404 	struct mapped_device *md = bdev->bd_disk->private_data;
405 
406 	return dm_get_geometry(md, geo);
407 }
408 
409 static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode,
410 			unsigned int cmd, unsigned long arg)
411 {
412 	struct mapped_device *md = bdev->bd_disk->private_data;
413 	int srcu_idx;
414 	struct dm_table *map;
415 	struct dm_target *tgt;
416 	int r = -ENOTTY;
417 
418 retry:
419 	map = dm_get_live_table(md, &srcu_idx);
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_put_live_table(md, srcu_idx);
440 
441 	if (r == -ENOTCONN) {
442 		msleep(10);
443 		goto retry;
444 	}
445 
446 	return r;
447 }
448 
449 static struct dm_io *alloc_io(struct mapped_device *md)
450 {
451 	return mempool_alloc(md->io_pool, GFP_NOIO);
452 }
453 
454 static void free_io(struct mapped_device *md, struct dm_io *io)
455 {
456 	mempool_free(io, md->io_pool);
457 }
458 
459 static void free_tio(struct mapped_device *md, struct dm_target_io *tio)
460 {
461 	bio_put(&tio->clone);
462 }
463 
464 static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md,
465 					    gfp_t gfp_mask)
466 {
467 	return mempool_alloc(md->io_pool, gfp_mask);
468 }
469 
470 static void free_rq_tio(struct dm_rq_target_io *tio)
471 {
472 	mempool_free(tio, tio->md->io_pool);
473 }
474 
475 static int md_in_flight(struct mapped_device *md)
476 {
477 	return atomic_read(&md->pending[READ]) +
478 	       atomic_read(&md->pending[WRITE]);
479 }
480 
481 static void start_io_acct(struct dm_io *io)
482 {
483 	struct mapped_device *md = io->md;
484 	struct bio *bio = io->bio;
485 	int cpu;
486 	int rw = bio_data_dir(bio);
487 
488 	io->start_time = jiffies;
489 
490 	cpu = part_stat_lock();
491 	part_round_stats(cpu, &dm_disk(md)->part0);
492 	part_stat_unlock();
493 	atomic_set(&dm_disk(md)->part0.in_flight[rw],
494 		atomic_inc_return(&md->pending[rw]));
495 
496 	if (unlikely(dm_stats_used(&md->stats)))
497 		dm_stats_account_io(&md->stats, bio->bi_rw, bio->bi_sector,
498 				    bio_sectors(bio), false, 0, &io->stats_aux);
499 }
500 
501 static void end_io_acct(struct dm_io *io)
502 {
503 	struct mapped_device *md = io->md;
504 	struct bio *bio = io->bio;
505 	unsigned long duration = jiffies - io->start_time;
506 	int pending, cpu;
507 	int rw = bio_data_dir(bio);
508 
509 	cpu = part_stat_lock();
510 	part_round_stats(cpu, &dm_disk(md)->part0);
511 	part_stat_add(cpu, &dm_disk(md)->part0, ticks[rw], duration);
512 	part_stat_unlock();
513 
514 	if (unlikely(dm_stats_used(&md->stats)))
515 		dm_stats_account_io(&md->stats, bio->bi_rw, bio->bi_sector,
516 				    bio_sectors(bio), true, duration, &io->stats_aux);
517 
518 	/*
519 	 * After this is decremented the bio must not be touched if it is
520 	 * a flush.
521 	 */
522 	pending = atomic_dec_return(&md->pending[rw]);
523 	atomic_set(&dm_disk(md)->part0.in_flight[rw], pending);
524 	pending += atomic_read(&md->pending[rw^0x1]);
525 
526 	/* nudge anyone waiting on suspend queue */
527 	if (!pending)
528 		wake_up(&md->wait);
529 }
530 
531 /*
532  * Add the bio to the list of deferred io.
533  */
534 static void queue_io(struct mapped_device *md, struct bio *bio)
535 {
536 	unsigned long flags;
537 
538 	spin_lock_irqsave(&md->deferred_lock, flags);
539 	bio_list_add(&md->deferred, bio);
540 	spin_unlock_irqrestore(&md->deferred_lock, flags);
541 	queue_work(md->wq, &md->work);
542 }
543 
544 /*
545  * Everyone (including functions in this file), should use this
546  * function to access the md->map field, and make sure they call
547  * dm_put_live_table() when finished.
548  */
549 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx) __acquires(md->io_barrier)
550 {
551 	*srcu_idx = srcu_read_lock(&md->io_barrier);
552 
553 	return srcu_dereference(md->map, &md->io_barrier);
554 }
555 
556 void dm_put_live_table(struct mapped_device *md, int srcu_idx) __releases(md->io_barrier)
557 {
558 	srcu_read_unlock(&md->io_barrier, srcu_idx);
559 }
560 
561 void dm_sync_table(struct mapped_device *md)
562 {
563 	synchronize_srcu(&md->io_barrier);
564 	synchronize_rcu_expedited();
565 }
566 
567 /*
568  * A fast alternative to dm_get_live_table/dm_put_live_table.
569  * The caller must not block between these two functions.
570  */
571 static struct dm_table *dm_get_live_table_fast(struct mapped_device *md) __acquires(RCU)
572 {
573 	rcu_read_lock();
574 	return rcu_dereference(md->map);
575 }
576 
577 static void dm_put_live_table_fast(struct mapped_device *md) __releases(RCU)
578 {
579 	rcu_read_unlock();
580 }
581 
582 /*
583  * Get the geometry associated with a dm device
584  */
585 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo)
586 {
587 	*geo = md->geometry;
588 
589 	return 0;
590 }
591 
592 /*
593  * Set the geometry of a device.
594  */
595 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo)
596 {
597 	sector_t sz = (sector_t)geo->cylinders * geo->heads * geo->sectors;
598 
599 	if (geo->start > sz) {
600 		DMWARN("Start sector is beyond the geometry limits.");
601 		return -EINVAL;
602 	}
603 
604 	md->geometry = *geo;
605 
606 	return 0;
607 }
608 
609 /*-----------------------------------------------------------------
610  * CRUD START:
611  *   A more elegant soln is in the works that uses the queue
612  *   merge fn, unfortunately there are a couple of changes to
613  *   the block layer that I want to make for this.  So in the
614  *   interests of getting something for people to use I give
615  *   you this clearly demarcated crap.
616  *---------------------------------------------------------------*/
617 
618 static int __noflush_suspending(struct mapped_device *md)
619 {
620 	return test_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
621 }
622 
623 /*
624  * Decrements the number of outstanding ios that a bio has been
625  * cloned into, completing the original io if necc.
626  */
627 static void dec_pending(struct dm_io *io, int error)
628 {
629 	unsigned long flags;
630 	int io_error;
631 	struct bio *bio;
632 	struct mapped_device *md = io->md;
633 
634 	/* Push-back supersedes any I/O errors */
635 	if (unlikely(error)) {
636 		spin_lock_irqsave(&io->endio_lock, flags);
637 		if (!(io->error > 0 && __noflush_suspending(md)))
638 			io->error = error;
639 		spin_unlock_irqrestore(&io->endio_lock, flags);
640 	}
641 
642 	if (atomic_dec_and_test(&io->io_count)) {
643 		if (io->error == DM_ENDIO_REQUEUE) {
644 			/*
645 			 * Target requested pushing back the I/O.
646 			 */
647 			spin_lock_irqsave(&md->deferred_lock, flags);
648 			if (__noflush_suspending(md))
649 				bio_list_add_head(&md->deferred, io->bio);
650 			else
651 				/* noflush suspend was interrupted. */
652 				io->error = -EIO;
653 			spin_unlock_irqrestore(&md->deferred_lock, flags);
654 		}
655 
656 		io_error = io->error;
657 		bio = io->bio;
658 		end_io_acct(io);
659 		free_io(md, io);
660 
661 		if (io_error == DM_ENDIO_REQUEUE)
662 			return;
663 
664 		if ((bio->bi_rw & REQ_FLUSH) && bio->bi_size) {
665 			/*
666 			 * Preflush done for flush with data, reissue
667 			 * without REQ_FLUSH.
668 			 */
669 			bio->bi_rw &= ~REQ_FLUSH;
670 			queue_io(md, bio);
671 		} else {
672 			/* done with normal IO or empty flush */
673 			trace_block_bio_complete(md->queue, bio, io_error);
674 			bio_endio(bio, io_error);
675 		}
676 	}
677 }
678 
679 static void clone_endio(struct bio *bio, int error)
680 {
681 	int r = 0;
682 	struct dm_target_io *tio = bio->bi_private;
683 	struct dm_io *io = tio->io;
684 	struct mapped_device *md = tio->io->md;
685 	dm_endio_fn endio = tio->ti->type->end_io;
686 
687 	if (!bio_flagged(bio, BIO_UPTODATE) && !error)
688 		error = -EIO;
689 
690 	if (endio) {
691 		r = endio(tio->ti, bio, error);
692 		if (r < 0 || r == DM_ENDIO_REQUEUE)
693 			/*
694 			 * error and requeue request are handled
695 			 * in dec_pending().
696 			 */
697 			error = r;
698 		else if (r == DM_ENDIO_INCOMPLETE)
699 			/* The target will handle the io */
700 			return;
701 		else if (r) {
702 			DMWARN("unimplemented target endio return value: %d", r);
703 			BUG();
704 		}
705 	}
706 
707 	free_tio(md, tio);
708 	dec_pending(io, error);
709 }
710 
711 /*
712  * Partial completion handling for request-based dm
713  */
714 static void end_clone_bio(struct bio *clone, int error)
715 {
716 	struct dm_rq_clone_bio_info *info = clone->bi_private;
717 	struct dm_rq_target_io *tio = info->tio;
718 	struct bio *bio = info->orig;
719 	unsigned int nr_bytes = info->orig->bi_size;
720 
721 	bio_put(clone);
722 
723 	if (tio->error)
724 		/*
725 		 * An error has already been detected on the request.
726 		 * Once error occurred, just let clone->end_io() handle
727 		 * the remainder.
728 		 */
729 		return;
730 	else if (error) {
731 		/*
732 		 * Don't notice the error to the upper layer yet.
733 		 * The error handling decision is made by the target driver,
734 		 * when the request is completed.
735 		 */
736 		tio->error = error;
737 		return;
738 	}
739 
740 	/*
741 	 * I/O for the bio successfully completed.
742 	 * Notice the data completion to the upper layer.
743 	 */
744 
745 	/*
746 	 * bios are processed from the head of the list.
747 	 * So the completing bio should always be rq->bio.
748 	 * If it's not, something wrong is happening.
749 	 */
750 	if (tio->orig->bio != bio)
751 		DMERR("bio completion is going in the middle of the request");
752 
753 	/*
754 	 * Update the original request.
755 	 * Do not use blk_end_request() here, because it may complete
756 	 * the original request before the clone, and break the ordering.
757 	 */
758 	blk_update_request(tio->orig, 0, nr_bytes);
759 }
760 
761 /*
762  * Don't touch any member of the md after calling this function because
763  * the md may be freed in dm_put() at the end of this function.
764  * Or do dm_get() before calling this function and dm_put() later.
765  */
766 static void rq_completed(struct mapped_device *md, int rw, int run_queue)
767 {
768 	atomic_dec(&md->pending[rw]);
769 
770 	/* nudge anyone waiting on suspend queue */
771 	if (!md_in_flight(md))
772 		wake_up(&md->wait);
773 
774 	/*
775 	 * Run this off this callpath, as drivers could invoke end_io while
776 	 * inside their request_fn (and holding the queue lock). Calling
777 	 * back into ->request_fn() could deadlock attempting to grab the
778 	 * queue lock again.
779 	 */
780 	if (run_queue)
781 		blk_run_queue_async(md->queue);
782 
783 	/*
784 	 * dm_put() must be at the end of this function. See the comment above
785 	 */
786 	dm_put(md);
787 }
788 
789 static void free_rq_clone(struct request *clone)
790 {
791 	struct dm_rq_target_io *tio = clone->end_io_data;
792 
793 	blk_rq_unprep_clone(clone);
794 	free_rq_tio(tio);
795 }
796 
797 /*
798  * Complete the clone and the original request.
799  * Must be called without queue lock.
800  */
801 static void dm_end_request(struct request *clone, int error)
802 {
803 	int rw = rq_data_dir(clone);
804 	struct dm_rq_target_io *tio = clone->end_io_data;
805 	struct mapped_device *md = tio->md;
806 	struct request *rq = tio->orig;
807 
808 	if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
809 		rq->errors = clone->errors;
810 		rq->resid_len = clone->resid_len;
811 
812 		if (rq->sense)
813 			/*
814 			 * We are using the sense buffer of the original
815 			 * request.
816 			 * So setting the length of the sense data is enough.
817 			 */
818 			rq->sense_len = clone->sense_len;
819 	}
820 
821 	free_rq_clone(clone);
822 	blk_end_request_all(rq, error);
823 	rq_completed(md, rw, true);
824 }
825 
826 static void dm_unprep_request(struct request *rq)
827 {
828 	struct request *clone = rq->special;
829 
830 	rq->special = NULL;
831 	rq->cmd_flags &= ~REQ_DONTPREP;
832 
833 	free_rq_clone(clone);
834 }
835 
836 /*
837  * Requeue the original request of a clone.
838  */
839 void dm_requeue_unmapped_request(struct request *clone)
840 {
841 	int rw = rq_data_dir(clone);
842 	struct dm_rq_target_io *tio = clone->end_io_data;
843 	struct mapped_device *md = tio->md;
844 	struct request *rq = tio->orig;
845 	struct request_queue *q = rq->q;
846 	unsigned long flags;
847 
848 	dm_unprep_request(rq);
849 
850 	spin_lock_irqsave(q->queue_lock, flags);
851 	blk_requeue_request(q, rq);
852 	spin_unlock_irqrestore(q->queue_lock, flags);
853 
854 	rq_completed(md, rw, 0);
855 }
856 EXPORT_SYMBOL_GPL(dm_requeue_unmapped_request);
857 
858 static void __stop_queue(struct request_queue *q)
859 {
860 	blk_stop_queue(q);
861 }
862 
863 static void stop_queue(struct request_queue *q)
864 {
865 	unsigned long flags;
866 
867 	spin_lock_irqsave(q->queue_lock, flags);
868 	__stop_queue(q);
869 	spin_unlock_irqrestore(q->queue_lock, flags);
870 }
871 
872 static void __start_queue(struct request_queue *q)
873 {
874 	if (blk_queue_stopped(q))
875 		blk_start_queue(q);
876 }
877 
878 static void start_queue(struct request_queue *q)
879 {
880 	unsigned long flags;
881 
882 	spin_lock_irqsave(q->queue_lock, flags);
883 	__start_queue(q);
884 	spin_unlock_irqrestore(q->queue_lock, flags);
885 }
886 
887 static void dm_done(struct request *clone, int error, bool mapped)
888 {
889 	int r = error;
890 	struct dm_rq_target_io *tio = clone->end_io_data;
891 	dm_request_endio_fn rq_end_io = NULL;
892 
893 	if (tio->ti) {
894 		rq_end_io = tio->ti->type->rq_end_io;
895 
896 		if (mapped && rq_end_io)
897 			r = rq_end_io(tio->ti, clone, error, &tio->info);
898 	}
899 
900 	if (r <= 0)
901 		/* The target wants to complete the I/O */
902 		dm_end_request(clone, r);
903 	else if (r == DM_ENDIO_INCOMPLETE)
904 		/* The target will handle the I/O */
905 		return;
906 	else if (r == DM_ENDIO_REQUEUE)
907 		/* The target wants to requeue the I/O */
908 		dm_requeue_unmapped_request(clone);
909 	else {
910 		DMWARN("unimplemented target endio return value: %d", r);
911 		BUG();
912 	}
913 }
914 
915 /*
916  * Request completion handler for request-based dm
917  */
918 static void dm_softirq_done(struct request *rq)
919 {
920 	bool mapped = true;
921 	struct request *clone = rq->completion_data;
922 	struct dm_rq_target_io *tio = clone->end_io_data;
923 
924 	if (rq->cmd_flags & REQ_FAILED)
925 		mapped = false;
926 
927 	dm_done(clone, tio->error, mapped);
928 }
929 
930 /*
931  * Complete the clone and the original request with the error status
932  * through softirq context.
933  */
934 static void dm_complete_request(struct request *clone, int error)
935 {
936 	struct dm_rq_target_io *tio = clone->end_io_data;
937 	struct request *rq = tio->orig;
938 
939 	tio->error = error;
940 	rq->completion_data = clone;
941 	blk_complete_request(rq);
942 }
943 
944 /*
945  * Complete the not-mapped clone and the original request with the error status
946  * through softirq context.
947  * Target's rq_end_io() function isn't called.
948  * This may be used when the target's map_rq() function fails.
949  */
950 void dm_kill_unmapped_request(struct request *clone, int error)
951 {
952 	struct dm_rq_target_io *tio = clone->end_io_data;
953 	struct request *rq = tio->orig;
954 
955 	rq->cmd_flags |= REQ_FAILED;
956 	dm_complete_request(clone, error);
957 }
958 EXPORT_SYMBOL_GPL(dm_kill_unmapped_request);
959 
960 /*
961  * Called with the queue lock held
962  */
963 static void end_clone_request(struct request *clone, int error)
964 {
965 	/*
966 	 * For just cleaning up the information of the queue in which
967 	 * the clone was dispatched.
968 	 * The clone is *NOT* freed actually here because it is alloced from
969 	 * dm own mempool and REQ_ALLOCED isn't set in clone->cmd_flags.
970 	 */
971 	__blk_put_request(clone->q, clone);
972 
973 	/*
974 	 * Actual request completion is done in a softirq context which doesn't
975 	 * hold the queue lock.  Otherwise, deadlock could occur because:
976 	 *     - another request may be submitted by the upper level driver
977 	 *       of the stacking during the completion
978 	 *     - the submission which requires queue lock may be done
979 	 *       against this queue
980 	 */
981 	dm_complete_request(clone, error);
982 }
983 
984 /*
985  * Return maximum size of I/O possible at the supplied sector up to the current
986  * target boundary.
987  */
988 static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti)
989 {
990 	sector_t target_offset = dm_target_offset(ti, sector);
991 
992 	return ti->len - target_offset;
993 }
994 
995 static sector_t max_io_len(sector_t sector, struct dm_target *ti)
996 {
997 	sector_t len = max_io_len_target_boundary(sector, ti);
998 	sector_t offset, max_len;
999 
1000 	/*
1001 	 * Does the target need to split even further?
1002 	 */
1003 	if (ti->max_io_len) {
1004 		offset = dm_target_offset(ti, sector);
1005 		if (unlikely(ti->max_io_len & (ti->max_io_len - 1)))
1006 			max_len = sector_div(offset, ti->max_io_len);
1007 		else
1008 			max_len = offset & (ti->max_io_len - 1);
1009 		max_len = ti->max_io_len - max_len;
1010 
1011 		if (len > max_len)
1012 			len = max_len;
1013 	}
1014 
1015 	return len;
1016 }
1017 
1018 int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
1019 {
1020 	if (len > UINT_MAX) {
1021 		DMERR("Specified maximum size of target IO (%llu) exceeds limit (%u)",
1022 		      (unsigned long long)len, UINT_MAX);
1023 		ti->error = "Maximum size of target IO is too large";
1024 		return -EINVAL;
1025 	}
1026 
1027 	ti->max_io_len = (uint32_t) len;
1028 
1029 	return 0;
1030 }
1031 EXPORT_SYMBOL_GPL(dm_set_target_max_io_len);
1032 
1033 static void __map_bio(struct dm_target_io *tio)
1034 {
1035 	int r;
1036 	sector_t sector;
1037 	struct mapped_device *md;
1038 	struct bio *clone = &tio->clone;
1039 	struct dm_target *ti = tio->ti;
1040 
1041 	clone->bi_end_io = clone_endio;
1042 	clone->bi_private = tio;
1043 
1044 	/*
1045 	 * Map the clone.  If r == 0 we don't need to do
1046 	 * anything, the target has assumed ownership of
1047 	 * this io.
1048 	 */
1049 	atomic_inc(&tio->io->io_count);
1050 	sector = clone->bi_sector;
1051 	r = ti->type->map(ti, clone);
1052 	if (r == DM_MAPIO_REMAPPED) {
1053 		/* the bio has been remapped so dispatch it */
1054 
1055 		trace_block_bio_remap(bdev_get_queue(clone->bi_bdev), clone,
1056 				      tio->io->bio->bi_bdev->bd_dev, sector);
1057 
1058 		generic_make_request(clone);
1059 	} else if (r < 0 || r == DM_MAPIO_REQUEUE) {
1060 		/* error the io and bail out, or requeue it if needed */
1061 		md = tio->io->md;
1062 		dec_pending(tio->io, r);
1063 		free_tio(md, tio);
1064 	} else if (r) {
1065 		DMWARN("unimplemented target map return value: %d", r);
1066 		BUG();
1067 	}
1068 }
1069 
1070 struct clone_info {
1071 	struct mapped_device *md;
1072 	struct dm_table *map;
1073 	struct bio *bio;
1074 	struct dm_io *io;
1075 	sector_t sector;
1076 	sector_t sector_count;
1077 	unsigned short idx;
1078 };
1079 
1080 static void bio_setup_sector(struct bio *bio, sector_t sector, sector_t len)
1081 {
1082 	bio->bi_sector = sector;
1083 	bio->bi_size = to_bytes(len);
1084 }
1085 
1086 static void bio_setup_bv(struct bio *bio, unsigned short idx, unsigned short bv_count)
1087 {
1088 	bio->bi_idx = idx;
1089 	bio->bi_vcnt = idx + bv_count;
1090 	bio->bi_flags &= ~(1 << BIO_SEG_VALID);
1091 }
1092 
1093 static void clone_bio_integrity(struct bio *bio, struct bio *clone,
1094 				unsigned short idx, unsigned len, unsigned offset,
1095 				unsigned trim)
1096 {
1097 	if (!bio_integrity(bio))
1098 		return;
1099 
1100 	bio_integrity_clone(clone, bio, GFP_NOIO);
1101 
1102 	if (trim)
1103 		bio_integrity_trim(clone, bio_sector_offset(bio, idx, offset), len);
1104 }
1105 
1106 /*
1107  * Creates a little bio that just does part of a bvec.
1108  */
1109 static void clone_split_bio(struct dm_target_io *tio, struct bio *bio,
1110 			    sector_t sector, unsigned short idx,
1111 			    unsigned offset, unsigned len)
1112 {
1113 	struct bio *clone = &tio->clone;
1114 	struct bio_vec *bv = bio->bi_io_vec + idx;
1115 
1116 	*clone->bi_io_vec = *bv;
1117 
1118 	bio_setup_sector(clone, sector, len);
1119 
1120 	clone->bi_bdev = bio->bi_bdev;
1121 	clone->bi_rw = bio->bi_rw;
1122 	clone->bi_vcnt = 1;
1123 	clone->bi_io_vec->bv_offset = offset;
1124 	clone->bi_io_vec->bv_len = clone->bi_size;
1125 	clone->bi_flags |= 1 << BIO_CLONED;
1126 
1127 	clone_bio_integrity(bio, clone, idx, len, offset, 1);
1128 }
1129 
1130 /*
1131  * Creates a bio that consists of range of complete bvecs.
1132  */
1133 static void clone_bio(struct dm_target_io *tio, struct bio *bio,
1134 		      sector_t sector, unsigned short idx,
1135 		      unsigned short bv_count, unsigned len)
1136 {
1137 	struct bio *clone = &tio->clone;
1138 	unsigned trim = 0;
1139 
1140 	__bio_clone(clone, bio);
1141 	bio_setup_sector(clone, sector, len);
1142 	bio_setup_bv(clone, idx, bv_count);
1143 
1144 	if (idx != bio->bi_idx || clone->bi_size < bio->bi_size)
1145 		trim = 1;
1146 	clone_bio_integrity(bio, clone, idx, len, 0, trim);
1147 }
1148 
1149 static struct dm_target_io *alloc_tio(struct clone_info *ci,
1150 				      struct dm_target *ti, int nr_iovecs,
1151 				      unsigned target_bio_nr)
1152 {
1153 	struct dm_target_io *tio;
1154 	struct bio *clone;
1155 
1156 	clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, ci->md->bs);
1157 	tio = container_of(clone, struct dm_target_io, clone);
1158 
1159 	tio->io = ci->io;
1160 	tio->ti = ti;
1161 	memset(&tio->info, 0, sizeof(tio->info));
1162 	tio->target_bio_nr = target_bio_nr;
1163 
1164 	return tio;
1165 }
1166 
1167 static void __clone_and_map_simple_bio(struct clone_info *ci,
1168 				       struct dm_target *ti,
1169 				       unsigned target_bio_nr, sector_t len)
1170 {
1171 	struct dm_target_io *tio = alloc_tio(ci, ti, ci->bio->bi_max_vecs, target_bio_nr);
1172 	struct bio *clone = &tio->clone;
1173 
1174 	/*
1175 	 * Discard requests require the bio's inline iovecs be initialized.
1176 	 * ci->bio->bi_max_vecs is BIO_INLINE_VECS anyway, for both flush
1177 	 * and discard, so no need for concern about wasted bvec allocations.
1178 	 */
1179 	 __bio_clone(clone, ci->bio);
1180 	if (len)
1181 		bio_setup_sector(clone, ci->sector, len);
1182 
1183 	__map_bio(tio);
1184 }
1185 
1186 static void __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti,
1187 				  unsigned num_bios, sector_t len)
1188 {
1189 	unsigned target_bio_nr;
1190 
1191 	for (target_bio_nr = 0; target_bio_nr < num_bios; target_bio_nr++)
1192 		__clone_and_map_simple_bio(ci, ti, target_bio_nr, len);
1193 }
1194 
1195 static int __send_empty_flush(struct clone_info *ci)
1196 {
1197 	unsigned target_nr = 0;
1198 	struct dm_target *ti;
1199 
1200 	BUG_ON(bio_has_data(ci->bio));
1201 	while ((ti = dm_table_get_target(ci->map, target_nr++)))
1202 		__send_duplicate_bios(ci, ti, ti->num_flush_bios, 0);
1203 
1204 	return 0;
1205 }
1206 
1207 static void __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti,
1208 				     sector_t sector, int nr_iovecs,
1209 				     unsigned short idx, unsigned short bv_count,
1210 				     unsigned offset, unsigned len,
1211 				     unsigned split_bvec)
1212 {
1213 	struct bio *bio = ci->bio;
1214 	struct dm_target_io *tio;
1215 	unsigned target_bio_nr;
1216 	unsigned num_target_bios = 1;
1217 
1218 	/*
1219 	 * Does the target want to receive duplicate copies of the bio?
1220 	 */
1221 	if (bio_data_dir(bio) == WRITE && ti->num_write_bios)
1222 		num_target_bios = ti->num_write_bios(ti, bio);
1223 
1224 	for (target_bio_nr = 0; target_bio_nr < num_target_bios; target_bio_nr++) {
1225 		tio = alloc_tio(ci, ti, nr_iovecs, target_bio_nr);
1226 		if (split_bvec)
1227 			clone_split_bio(tio, bio, sector, idx, offset, len);
1228 		else
1229 			clone_bio(tio, bio, sector, idx, bv_count, len);
1230 		__map_bio(tio);
1231 	}
1232 }
1233 
1234 typedef unsigned (*get_num_bios_fn)(struct dm_target *ti);
1235 
1236 static unsigned get_num_discard_bios(struct dm_target *ti)
1237 {
1238 	return ti->num_discard_bios;
1239 }
1240 
1241 static unsigned get_num_write_same_bios(struct dm_target *ti)
1242 {
1243 	return ti->num_write_same_bios;
1244 }
1245 
1246 typedef bool (*is_split_required_fn)(struct dm_target *ti);
1247 
1248 static bool is_split_required_for_discard(struct dm_target *ti)
1249 {
1250 	return ti->split_discard_bios;
1251 }
1252 
1253 static int __send_changing_extent_only(struct clone_info *ci,
1254 				       get_num_bios_fn get_num_bios,
1255 				       is_split_required_fn is_split_required)
1256 {
1257 	struct dm_target *ti;
1258 	sector_t len;
1259 	unsigned num_bios;
1260 
1261 	do {
1262 		ti = dm_table_find_target(ci->map, ci->sector);
1263 		if (!dm_target_is_valid(ti))
1264 			return -EIO;
1265 
1266 		/*
1267 		 * Even though the device advertised support for this type of
1268 		 * request, that does not mean every target supports it, and
1269 		 * reconfiguration might also have changed that since the
1270 		 * check was performed.
1271 		 */
1272 		num_bios = get_num_bios ? get_num_bios(ti) : 0;
1273 		if (!num_bios)
1274 			return -EOPNOTSUPP;
1275 
1276 		if (is_split_required && !is_split_required(ti))
1277 			len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
1278 		else
1279 			len = min(ci->sector_count, max_io_len(ci->sector, ti));
1280 
1281 		__send_duplicate_bios(ci, ti, num_bios, len);
1282 
1283 		ci->sector += len;
1284 	} while (ci->sector_count -= len);
1285 
1286 	return 0;
1287 }
1288 
1289 static int __send_discard(struct clone_info *ci)
1290 {
1291 	return __send_changing_extent_only(ci, get_num_discard_bios,
1292 					   is_split_required_for_discard);
1293 }
1294 
1295 static int __send_write_same(struct clone_info *ci)
1296 {
1297 	return __send_changing_extent_only(ci, get_num_write_same_bios, NULL);
1298 }
1299 
1300 /*
1301  * Find maximum number of sectors / bvecs we can process with a single bio.
1302  */
1303 static sector_t __len_within_target(struct clone_info *ci, sector_t max, int *idx)
1304 {
1305 	struct bio *bio = ci->bio;
1306 	sector_t bv_len, total_len = 0;
1307 
1308 	for (*idx = ci->idx; max && (*idx < bio->bi_vcnt); (*idx)++) {
1309 		bv_len = to_sector(bio->bi_io_vec[*idx].bv_len);
1310 
1311 		if (bv_len > max)
1312 			break;
1313 
1314 		max -= bv_len;
1315 		total_len += bv_len;
1316 	}
1317 
1318 	return total_len;
1319 }
1320 
1321 static int __split_bvec_across_targets(struct clone_info *ci,
1322 				       struct dm_target *ti, sector_t max)
1323 {
1324 	struct bio *bio = ci->bio;
1325 	struct bio_vec *bv = bio->bi_io_vec + ci->idx;
1326 	sector_t remaining = to_sector(bv->bv_len);
1327 	unsigned offset = 0;
1328 	sector_t len;
1329 
1330 	do {
1331 		if (offset) {
1332 			ti = dm_table_find_target(ci->map, ci->sector);
1333 			if (!dm_target_is_valid(ti))
1334 				return -EIO;
1335 
1336 			max = max_io_len(ci->sector, ti);
1337 		}
1338 
1339 		len = min(remaining, max);
1340 
1341 		__clone_and_map_data_bio(ci, ti, ci->sector, 1, ci->idx, 0,
1342 					 bv->bv_offset + offset, len, 1);
1343 
1344 		ci->sector += len;
1345 		ci->sector_count -= len;
1346 		offset += to_bytes(len);
1347 	} while (remaining -= len);
1348 
1349 	ci->idx++;
1350 
1351 	return 0;
1352 }
1353 
1354 /*
1355  * Select the correct strategy for processing a non-flush bio.
1356  */
1357 static int __split_and_process_non_flush(struct clone_info *ci)
1358 {
1359 	struct bio *bio = ci->bio;
1360 	struct dm_target *ti;
1361 	sector_t len, max;
1362 	int idx;
1363 
1364 	if (unlikely(bio->bi_rw & REQ_DISCARD))
1365 		return __send_discard(ci);
1366 	else if (unlikely(bio->bi_rw & REQ_WRITE_SAME))
1367 		return __send_write_same(ci);
1368 
1369 	ti = dm_table_find_target(ci->map, ci->sector);
1370 	if (!dm_target_is_valid(ti))
1371 		return -EIO;
1372 
1373 	max = max_io_len(ci->sector, ti);
1374 
1375 	/*
1376 	 * Optimise for the simple case where we can do all of
1377 	 * the remaining io with a single clone.
1378 	 */
1379 	if (ci->sector_count <= max) {
1380 		__clone_and_map_data_bio(ci, ti, ci->sector, bio->bi_max_vecs,
1381 					 ci->idx, bio->bi_vcnt - ci->idx, 0,
1382 					 ci->sector_count, 0);
1383 		ci->sector_count = 0;
1384 		return 0;
1385 	}
1386 
1387 	/*
1388 	 * There are some bvecs that don't span targets.
1389 	 * Do as many of these as possible.
1390 	 */
1391 	if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) {
1392 		len = __len_within_target(ci, max, &idx);
1393 
1394 		__clone_and_map_data_bio(ci, ti, ci->sector, bio->bi_max_vecs,
1395 					 ci->idx, idx - ci->idx, 0, len, 0);
1396 
1397 		ci->sector += len;
1398 		ci->sector_count -= len;
1399 		ci->idx = idx;
1400 
1401 		return 0;
1402 	}
1403 
1404 	/*
1405 	 * Handle a bvec that must be split between two or more targets.
1406 	 */
1407 	return __split_bvec_across_targets(ci, ti, max);
1408 }
1409 
1410 /*
1411  * Entry point to split a bio into clones and submit them to the targets.
1412  */
1413 static void __split_and_process_bio(struct mapped_device *md,
1414 				    struct dm_table *map, struct bio *bio)
1415 {
1416 	struct clone_info ci;
1417 	int error = 0;
1418 
1419 	if (unlikely(!map)) {
1420 		bio_io_error(bio);
1421 		return;
1422 	}
1423 
1424 	ci.map = map;
1425 	ci.md = md;
1426 	ci.io = alloc_io(md);
1427 	ci.io->error = 0;
1428 	atomic_set(&ci.io->io_count, 1);
1429 	ci.io->bio = bio;
1430 	ci.io->md = md;
1431 	spin_lock_init(&ci.io->endio_lock);
1432 	ci.sector = bio->bi_sector;
1433 	ci.idx = bio->bi_idx;
1434 
1435 	start_io_acct(ci.io);
1436 
1437 	if (bio->bi_rw & REQ_FLUSH) {
1438 		ci.bio = &ci.md->flush_bio;
1439 		ci.sector_count = 0;
1440 		error = __send_empty_flush(&ci);
1441 		/* dec_pending submits any data associated with flush */
1442 	} else {
1443 		ci.bio = bio;
1444 		ci.sector_count = bio_sectors(bio);
1445 		while (ci.sector_count && !error)
1446 			error = __split_and_process_non_flush(&ci);
1447 	}
1448 
1449 	/* drop the extra reference count */
1450 	dec_pending(ci.io, error);
1451 }
1452 /*-----------------------------------------------------------------
1453  * CRUD END
1454  *---------------------------------------------------------------*/
1455 
1456 static int dm_merge_bvec(struct request_queue *q,
1457 			 struct bvec_merge_data *bvm,
1458 			 struct bio_vec *biovec)
1459 {
1460 	struct mapped_device *md = q->queuedata;
1461 	struct dm_table *map = dm_get_live_table_fast(md);
1462 	struct dm_target *ti;
1463 	sector_t max_sectors;
1464 	int max_size = 0;
1465 
1466 	if (unlikely(!map))
1467 		goto out;
1468 
1469 	ti = dm_table_find_target(map, bvm->bi_sector);
1470 	if (!dm_target_is_valid(ti))
1471 		goto out;
1472 
1473 	/*
1474 	 * Find maximum amount of I/O that won't need splitting
1475 	 */
1476 	max_sectors = min(max_io_len(bvm->bi_sector, ti),
1477 			  (sector_t) BIO_MAX_SECTORS);
1478 	max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
1479 	if (max_size < 0)
1480 		max_size = 0;
1481 
1482 	/*
1483 	 * merge_bvec_fn() returns number of bytes
1484 	 * it can accept at this offset
1485 	 * max is precomputed maximal io size
1486 	 */
1487 	if (max_size && ti->type->merge)
1488 		max_size = ti->type->merge(ti, bvm, biovec, max_size);
1489 	/*
1490 	 * If the target doesn't support merge method and some of the devices
1491 	 * provided their merge_bvec method (we know this by looking at
1492 	 * queue_max_hw_sectors), then we can't allow bios with multiple vector
1493 	 * entries.  So always set max_size to 0, and the code below allows
1494 	 * just one page.
1495 	 */
1496 	else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9)
1497 
1498 		max_size = 0;
1499 
1500 out:
1501 	dm_put_live_table_fast(md);
1502 	/*
1503 	 * Always allow an entire first page
1504 	 */
1505 	if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT))
1506 		max_size = biovec->bv_len;
1507 
1508 	return max_size;
1509 }
1510 
1511 /*
1512  * The request function that just remaps the bio built up by
1513  * dm_merge_bvec.
1514  */
1515 static void _dm_request(struct request_queue *q, struct bio *bio)
1516 {
1517 	int rw = bio_data_dir(bio);
1518 	struct mapped_device *md = q->queuedata;
1519 	int cpu;
1520 	int srcu_idx;
1521 	struct dm_table *map;
1522 
1523 	map = dm_get_live_table(md, &srcu_idx);
1524 
1525 	cpu = part_stat_lock();
1526 	part_stat_inc(cpu, &dm_disk(md)->part0, ios[rw]);
1527 	part_stat_add(cpu, &dm_disk(md)->part0, sectors[rw], bio_sectors(bio));
1528 	part_stat_unlock();
1529 
1530 	/* if we're suspended, we have to queue this io for later */
1531 	if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) {
1532 		dm_put_live_table(md, srcu_idx);
1533 
1534 		if (bio_rw(bio) != READA)
1535 			queue_io(md, bio);
1536 		else
1537 			bio_io_error(bio);
1538 		return;
1539 	}
1540 
1541 	__split_and_process_bio(md, map, bio);
1542 	dm_put_live_table(md, srcu_idx);
1543 	return;
1544 }
1545 
1546 int dm_request_based(struct mapped_device *md)
1547 {
1548 	return blk_queue_stackable(md->queue);
1549 }
1550 
1551 static void dm_request(struct request_queue *q, struct bio *bio)
1552 {
1553 	struct mapped_device *md = q->queuedata;
1554 
1555 	if (dm_request_based(md))
1556 		blk_queue_bio(q, bio);
1557 	else
1558 		_dm_request(q, bio);
1559 }
1560 
1561 void dm_dispatch_request(struct request *rq)
1562 {
1563 	int r;
1564 
1565 	if (blk_queue_io_stat(rq->q))
1566 		rq->cmd_flags |= REQ_IO_STAT;
1567 
1568 	rq->start_time = jiffies;
1569 	r = blk_insert_cloned_request(rq->q, rq);
1570 	if (r)
1571 		dm_complete_request(rq, r);
1572 }
1573 EXPORT_SYMBOL_GPL(dm_dispatch_request);
1574 
1575 static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
1576 				 void *data)
1577 {
1578 	struct dm_rq_target_io *tio = data;
1579 	struct dm_rq_clone_bio_info *info =
1580 		container_of(bio, struct dm_rq_clone_bio_info, clone);
1581 
1582 	info->orig = bio_orig;
1583 	info->tio = tio;
1584 	bio->bi_end_io = end_clone_bio;
1585 	bio->bi_private = info;
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 	r = blk_rq_prep_clone(clone, rq, tio->md->bs, GFP_ATOMIC,
1596 			      dm_rq_bio_constructor, tio);
1597 	if (r)
1598 		return r;
1599 
1600 	clone->cmd = rq->cmd;
1601 	clone->cmd_len = rq->cmd_len;
1602 	clone->sense = rq->sense;
1603 	clone->buffer = rq->buffer;
1604 	clone->end_io = end_clone_request;
1605 	clone->end_io_data = tio;
1606 
1607 	return 0;
1608 }
1609 
1610 static struct request *clone_rq(struct request *rq, struct mapped_device *md,
1611 				gfp_t gfp_mask)
1612 {
1613 	struct request *clone;
1614 	struct dm_rq_target_io *tio;
1615 
1616 	tio = alloc_rq_tio(md, gfp_mask);
1617 	if (!tio)
1618 		return NULL;
1619 
1620 	tio->md = md;
1621 	tio->ti = NULL;
1622 	tio->orig = rq;
1623 	tio->error = 0;
1624 	memset(&tio->info, 0, sizeof(tio->info));
1625 
1626 	clone = &tio->clone;
1627 	if (setup_clone(clone, rq, tio)) {
1628 		/* -ENOMEM */
1629 		free_rq_tio(tio);
1630 		return NULL;
1631 	}
1632 
1633 	return clone;
1634 }
1635 
1636 /*
1637  * Called with the queue lock held.
1638  */
1639 static int dm_prep_fn(struct request_queue *q, struct request *rq)
1640 {
1641 	struct mapped_device *md = q->queuedata;
1642 	struct request *clone;
1643 
1644 	if (unlikely(rq->special)) {
1645 		DMWARN("Already has something in rq->special.");
1646 		return BLKPREP_KILL;
1647 	}
1648 
1649 	clone = clone_rq(rq, md, GFP_ATOMIC);
1650 	if (!clone)
1651 		return BLKPREP_DEFER;
1652 
1653 	rq->special = clone;
1654 	rq->cmd_flags |= REQ_DONTPREP;
1655 
1656 	return BLKPREP_OK;
1657 }
1658 
1659 /*
1660  * Returns:
1661  * 0  : the request has been processed (not requeued)
1662  * !0 : the request has been requeued
1663  */
1664 static int map_request(struct dm_target *ti, struct request *clone,
1665 		       struct mapped_device *md)
1666 {
1667 	int r, requeued = 0;
1668 	struct dm_rq_target_io *tio = clone->end_io_data;
1669 
1670 	tio->ti = ti;
1671 	r = ti->type->map_rq(ti, clone, &tio->info);
1672 	switch (r) {
1673 	case DM_MAPIO_SUBMITTED:
1674 		/* The target has taken the I/O to submit by itself later */
1675 		break;
1676 	case DM_MAPIO_REMAPPED:
1677 		/* The target has remapped the I/O so dispatch it */
1678 		trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
1679 				     blk_rq_pos(tio->orig));
1680 		dm_dispatch_request(clone);
1681 		break;
1682 	case DM_MAPIO_REQUEUE:
1683 		/* The target wants to requeue the I/O */
1684 		dm_requeue_unmapped_request(clone);
1685 		requeued = 1;
1686 		break;
1687 	default:
1688 		if (r > 0) {
1689 			DMWARN("unimplemented target map return value: %d", r);
1690 			BUG();
1691 		}
1692 
1693 		/* The target wants to complete the I/O */
1694 		dm_kill_unmapped_request(clone, r);
1695 		break;
1696 	}
1697 
1698 	return requeued;
1699 }
1700 
1701 static struct request *dm_start_request(struct mapped_device *md, struct request *orig)
1702 {
1703 	struct request *clone;
1704 
1705 	blk_start_request(orig);
1706 	clone = orig->special;
1707 	atomic_inc(&md->pending[rq_data_dir(clone)]);
1708 
1709 	/*
1710 	 * Hold the md reference here for the in-flight I/O.
1711 	 * We can't rely on the reference count by device opener,
1712 	 * because the device may be closed during the request completion
1713 	 * when all bios are completed.
1714 	 * See the comment in rq_completed() too.
1715 	 */
1716 	dm_get(md);
1717 
1718 	return clone;
1719 }
1720 
1721 /*
1722  * q->request_fn for request-based dm.
1723  * Called with the queue lock held.
1724  */
1725 static void dm_request_fn(struct request_queue *q)
1726 {
1727 	struct mapped_device *md = q->queuedata;
1728 	int srcu_idx;
1729 	struct dm_table *map = dm_get_live_table(md, &srcu_idx);
1730 	struct dm_target *ti;
1731 	struct request *rq, *clone;
1732 	sector_t pos;
1733 
1734 	/*
1735 	 * For suspend, check blk_queue_stopped() and increment
1736 	 * ->pending within a single queue_lock not to increment the
1737 	 * number of in-flight I/Os after the queue is stopped in
1738 	 * dm_suspend().
1739 	 */
1740 	while (!blk_queue_stopped(q)) {
1741 		rq = blk_peek_request(q);
1742 		if (!rq)
1743 			goto delay_and_out;
1744 
1745 		/* always use block 0 to find the target for flushes for now */
1746 		pos = 0;
1747 		if (!(rq->cmd_flags & REQ_FLUSH))
1748 			pos = blk_rq_pos(rq);
1749 
1750 		ti = dm_table_find_target(map, pos);
1751 		if (!dm_target_is_valid(ti)) {
1752 			/*
1753 			 * Must perform setup, that dm_done() requires,
1754 			 * before calling dm_kill_unmapped_request
1755 			 */
1756 			DMERR_LIMIT("request attempted access beyond the end of device");
1757 			clone = dm_start_request(md, rq);
1758 			dm_kill_unmapped_request(clone, -EIO);
1759 			continue;
1760 		}
1761 
1762 		if (ti->type->busy && ti->type->busy(ti))
1763 			goto delay_and_out;
1764 
1765 		clone = dm_start_request(md, rq);
1766 
1767 		spin_unlock(q->queue_lock);
1768 		if (map_request(ti, clone, md))
1769 			goto requeued;
1770 
1771 		BUG_ON(!irqs_disabled());
1772 		spin_lock(q->queue_lock);
1773 	}
1774 
1775 	goto out;
1776 
1777 requeued:
1778 	BUG_ON(!irqs_disabled());
1779 	spin_lock(q->queue_lock);
1780 
1781 delay_and_out:
1782 	blk_delay_queue(q, HZ / 10);
1783 out:
1784 	dm_put_live_table(md, srcu_idx);
1785 }
1786 
1787 int dm_underlying_device_busy(struct request_queue *q)
1788 {
1789 	return blk_lld_busy(q);
1790 }
1791 EXPORT_SYMBOL_GPL(dm_underlying_device_busy);
1792 
1793 static int dm_lld_busy(struct request_queue *q)
1794 {
1795 	int r;
1796 	struct mapped_device *md = q->queuedata;
1797 	struct dm_table *map = dm_get_live_table_fast(md);
1798 
1799 	if (!map || test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))
1800 		r = 1;
1801 	else
1802 		r = dm_table_any_busy_target(map);
1803 
1804 	dm_put_live_table_fast(md);
1805 
1806 	return r;
1807 }
1808 
1809 static int dm_any_congested(void *congested_data, int bdi_bits)
1810 {
1811 	int r = bdi_bits;
1812 	struct mapped_device *md = congested_data;
1813 	struct dm_table *map;
1814 
1815 	if (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
1816 		map = dm_get_live_table_fast(md);
1817 		if (map) {
1818 			/*
1819 			 * Request-based dm cares about only own queue for
1820 			 * the query about congestion status of request_queue
1821 			 */
1822 			if (dm_request_based(md))
1823 				r = md->queue->backing_dev_info.state &
1824 				    bdi_bits;
1825 			else
1826 				r = dm_table_any_congested(map, bdi_bits);
1827 		}
1828 		dm_put_live_table_fast(md);
1829 	}
1830 
1831 	return r;
1832 }
1833 
1834 /*-----------------------------------------------------------------
1835  * An IDR is used to keep track of allocated minor numbers.
1836  *---------------------------------------------------------------*/
1837 static void free_minor(int minor)
1838 {
1839 	spin_lock(&_minor_lock);
1840 	idr_remove(&_minor_idr, minor);
1841 	spin_unlock(&_minor_lock);
1842 }
1843 
1844 /*
1845  * See if the device with a specific minor # is free.
1846  */
1847 static int specific_minor(int minor)
1848 {
1849 	int r;
1850 
1851 	if (minor >= (1 << MINORBITS))
1852 		return -EINVAL;
1853 
1854 	idr_preload(GFP_KERNEL);
1855 	spin_lock(&_minor_lock);
1856 
1857 	r = idr_alloc(&_minor_idr, MINOR_ALLOCED, minor, minor + 1, GFP_NOWAIT);
1858 
1859 	spin_unlock(&_minor_lock);
1860 	idr_preload_end();
1861 	if (r < 0)
1862 		return r == -ENOSPC ? -EBUSY : r;
1863 	return 0;
1864 }
1865 
1866 static int next_free_minor(int *minor)
1867 {
1868 	int r;
1869 
1870 	idr_preload(GFP_KERNEL);
1871 	spin_lock(&_minor_lock);
1872 
1873 	r = idr_alloc(&_minor_idr, MINOR_ALLOCED, 0, 1 << MINORBITS, GFP_NOWAIT);
1874 
1875 	spin_unlock(&_minor_lock);
1876 	idr_preload_end();
1877 	if (r < 0)
1878 		return r;
1879 	*minor = r;
1880 	return 0;
1881 }
1882 
1883 static const struct block_device_operations dm_blk_dops;
1884 
1885 static void dm_wq_work(struct work_struct *work);
1886 
1887 static void dm_init_md_queue(struct mapped_device *md)
1888 {
1889 	/*
1890 	 * Request-based dm devices cannot be stacked on top of bio-based dm
1891 	 * devices.  The type of this dm device has not been decided yet.
1892 	 * The type is decided at the first table loading time.
1893 	 * To prevent problematic device stacking, clear the queue flag
1894 	 * for request stacking support until then.
1895 	 *
1896 	 * This queue is new, so no concurrency on the queue_flags.
1897 	 */
1898 	queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue);
1899 
1900 	md->queue->queuedata = md;
1901 	md->queue->backing_dev_info.congested_fn = dm_any_congested;
1902 	md->queue->backing_dev_info.congested_data = md;
1903 	blk_queue_make_request(md->queue, dm_request);
1904 	blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
1905 	blk_queue_merge_bvec(md->queue, dm_merge_bvec);
1906 }
1907 
1908 /*
1909  * Allocate and initialise a blank device with a given minor.
1910  */
1911 static struct mapped_device *alloc_dev(int minor)
1912 {
1913 	int r;
1914 	struct mapped_device *md = kzalloc(sizeof(*md), GFP_KERNEL);
1915 	void *old_md;
1916 
1917 	if (!md) {
1918 		DMWARN("unable to allocate device, out of memory.");
1919 		return NULL;
1920 	}
1921 
1922 	if (!try_module_get(THIS_MODULE))
1923 		goto bad_module_get;
1924 
1925 	/* get a minor number for the dev */
1926 	if (minor == DM_ANY_MINOR)
1927 		r = next_free_minor(&minor);
1928 	else
1929 		r = specific_minor(minor);
1930 	if (r < 0)
1931 		goto bad_minor;
1932 
1933 	r = init_srcu_struct(&md->io_barrier);
1934 	if (r < 0)
1935 		goto bad_io_barrier;
1936 
1937 	md->type = DM_TYPE_NONE;
1938 	mutex_init(&md->suspend_lock);
1939 	mutex_init(&md->type_lock);
1940 	spin_lock_init(&md->deferred_lock);
1941 	atomic_set(&md->holders, 1);
1942 	atomic_set(&md->open_count, 0);
1943 	atomic_set(&md->event_nr, 0);
1944 	atomic_set(&md->uevent_seq, 0);
1945 	INIT_LIST_HEAD(&md->uevent_list);
1946 	spin_lock_init(&md->uevent_lock);
1947 
1948 	md->queue = blk_alloc_queue(GFP_KERNEL);
1949 	if (!md->queue)
1950 		goto bad_queue;
1951 
1952 	dm_init_md_queue(md);
1953 
1954 	md->disk = alloc_disk(1);
1955 	if (!md->disk)
1956 		goto bad_disk;
1957 
1958 	atomic_set(&md->pending[0], 0);
1959 	atomic_set(&md->pending[1], 0);
1960 	init_waitqueue_head(&md->wait);
1961 	INIT_WORK(&md->work, dm_wq_work);
1962 	init_waitqueue_head(&md->eventq);
1963 
1964 	md->disk->major = _major;
1965 	md->disk->first_minor = minor;
1966 	md->disk->fops = &dm_blk_dops;
1967 	md->disk->queue = md->queue;
1968 	md->disk->private_data = md;
1969 	sprintf(md->disk->disk_name, "dm-%d", minor);
1970 	add_disk(md->disk);
1971 	format_dev_t(md->name, MKDEV(_major, minor));
1972 
1973 	md->wq = alloc_workqueue("kdmflush", WQ_MEM_RECLAIM, 0);
1974 	if (!md->wq)
1975 		goto bad_thread;
1976 
1977 	md->bdev = bdget_disk(md->disk, 0);
1978 	if (!md->bdev)
1979 		goto bad_bdev;
1980 
1981 	bio_init(&md->flush_bio);
1982 	md->flush_bio.bi_bdev = md->bdev;
1983 	md->flush_bio.bi_rw = WRITE_FLUSH;
1984 
1985 	dm_stats_init(&md->stats);
1986 
1987 	/* Populate the mapping, nobody knows we exist yet */
1988 	spin_lock(&_minor_lock);
1989 	old_md = idr_replace(&_minor_idr, md, minor);
1990 	spin_unlock(&_minor_lock);
1991 
1992 	BUG_ON(old_md != MINOR_ALLOCED);
1993 
1994 	return md;
1995 
1996 bad_bdev:
1997 	destroy_workqueue(md->wq);
1998 bad_thread:
1999 	del_gendisk(md->disk);
2000 	put_disk(md->disk);
2001 bad_disk:
2002 	blk_cleanup_queue(md->queue);
2003 bad_queue:
2004 	cleanup_srcu_struct(&md->io_barrier);
2005 bad_io_barrier:
2006 	free_minor(minor);
2007 bad_minor:
2008 	module_put(THIS_MODULE);
2009 bad_module_get:
2010 	kfree(md);
2011 	return NULL;
2012 }
2013 
2014 static void unlock_fs(struct mapped_device *md);
2015 
2016 static void free_dev(struct mapped_device *md)
2017 {
2018 	int minor = MINOR(disk_devt(md->disk));
2019 
2020 	unlock_fs(md);
2021 	bdput(md->bdev);
2022 	destroy_workqueue(md->wq);
2023 	if (md->io_pool)
2024 		mempool_destroy(md->io_pool);
2025 	if (md->bs)
2026 		bioset_free(md->bs);
2027 	blk_integrity_unregister(md->disk);
2028 	del_gendisk(md->disk);
2029 	cleanup_srcu_struct(&md->io_barrier);
2030 	free_minor(minor);
2031 
2032 	spin_lock(&_minor_lock);
2033 	md->disk->private_data = NULL;
2034 	spin_unlock(&_minor_lock);
2035 
2036 	put_disk(md->disk);
2037 	blk_cleanup_queue(md->queue);
2038 	dm_stats_cleanup(&md->stats);
2039 	module_put(THIS_MODULE);
2040 	kfree(md);
2041 }
2042 
2043 static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
2044 {
2045 	struct dm_md_mempools *p = dm_table_get_md_mempools(t);
2046 
2047 	if (md->io_pool && md->bs) {
2048 		/* The md already has necessary mempools. */
2049 		if (dm_table_get_type(t) == DM_TYPE_BIO_BASED) {
2050 			/*
2051 			 * Reload bioset because front_pad may have changed
2052 			 * because a different table was loaded.
2053 			 */
2054 			bioset_free(md->bs);
2055 			md->bs = p->bs;
2056 			p->bs = NULL;
2057 		} else if (dm_table_get_type(t) == DM_TYPE_REQUEST_BASED) {
2058 			/*
2059 			 * There's no need to reload with request-based dm
2060 			 * because the size of front_pad doesn't change.
2061 			 * Note for future: If you are to reload bioset,
2062 			 * prep-ed requests in the queue may refer
2063 			 * to bio from the old bioset, so you must walk
2064 			 * through the queue to unprep.
2065 			 */
2066 		}
2067 		goto out;
2068 	}
2069 
2070 	BUG_ON(!p || md->io_pool || md->bs);
2071 
2072 	md->io_pool = p->io_pool;
2073 	p->io_pool = NULL;
2074 	md->bs = p->bs;
2075 	p->bs = NULL;
2076 
2077 out:
2078 	/* mempool bind completed, now no need any mempools in the table */
2079 	dm_table_free_md_mempools(t);
2080 }
2081 
2082 /*
2083  * Bind a table to the device.
2084  */
2085 static void event_callback(void *context)
2086 {
2087 	unsigned long flags;
2088 	LIST_HEAD(uevents);
2089 	struct mapped_device *md = (struct mapped_device *) context;
2090 
2091 	spin_lock_irqsave(&md->uevent_lock, flags);
2092 	list_splice_init(&md->uevent_list, &uevents);
2093 	spin_unlock_irqrestore(&md->uevent_lock, flags);
2094 
2095 	dm_send_uevents(&uevents, &disk_to_dev(md->disk)->kobj);
2096 
2097 	atomic_inc(&md->event_nr);
2098 	wake_up(&md->eventq);
2099 }
2100 
2101 /*
2102  * Protected by md->suspend_lock obtained by dm_swap_table().
2103  */
2104 static void __set_size(struct mapped_device *md, sector_t size)
2105 {
2106 	set_capacity(md->disk, size);
2107 
2108 	i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
2109 }
2110 
2111 /*
2112  * Return 1 if the queue has a compulsory merge_bvec_fn function.
2113  *
2114  * If this function returns 0, then the device is either a non-dm
2115  * device without a merge_bvec_fn, or it is a dm device that is
2116  * able to split any bios it receives that are too big.
2117  */
2118 int dm_queue_merge_is_compulsory(struct request_queue *q)
2119 {
2120 	struct mapped_device *dev_md;
2121 
2122 	if (!q->merge_bvec_fn)
2123 		return 0;
2124 
2125 	if (q->make_request_fn == dm_request) {
2126 		dev_md = q->queuedata;
2127 		if (test_bit(DMF_MERGE_IS_OPTIONAL, &dev_md->flags))
2128 			return 0;
2129 	}
2130 
2131 	return 1;
2132 }
2133 
2134 static int dm_device_merge_is_compulsory(struct dm_target *ti,
2135 					 struct dm_dev *dev, sector_t start,
2136 					 sector_t len, void *data)
2137 {
2138 	struct block_device *bdev = dev->bdev;
2139 	struct request_queue *q = bdev_get_queue(bdev);
2140 
2141 	return dm_queue_merge_is_compulsory(q);
2142 }
2143 
2144 /*
2145  * Return 1 if it is acceptable to ignore merge_bvec_fn based
2146  * on the properties of the underlying devices.
2147  */
2148 static int dm_table_merge_is_optional(struct dm_table *table)
2149 {
2150 	unsigned i = 0;
2151 	struct dm_target *ti;
2152 
2153 	while (i < dm_table_get_num_targets(table)) {
2154 		ti = dm_table_get_target(table, i++);
2155 
2156 		if (ti->type->iterate_devices &&
2157 		    ti->type->iterate_devices(ti, dm_device_merge_is_compulsory, NULL))
2158 			return 0;
2159 	}
2160 
2161 	return 1;
2162 }
2163 
2164 /*
2165  * Returns old map, which caller must destroy.
2166  */
2167 static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
2168 			       struct queue_limits *limits)
2169 {
2170 	struct dm_table *old_map;
2171 	struct request_queue *q = md->queue;
2172 	sector_t size;
2173 	int merge_is_optional;
2174 
2175 	size = dm_table_get_size(t);
2176 
2177 	/*
2178 	 * Wipe any geometry if the size of the table changed.
2179 	 */
2180 	if (size != dm_get_size(md))
2181 		memset(&md->geometry, 0, sizeof(md->geometry));
2182 
2183 	__set_size(md, size);
2184 
2185 	dm_table_event_callback(t, event_callback, md);
2186 
2187 	/*
2188 	 * The queue hasn't been stopped yet, if the old table type wasn't
2189 	 * for request-based during suspension.  So stop it to prevent
2190 	 * I/O mapping before resume.
2191 	 * This must be done before setting the queue restrictions,
2192 	 * because request-based dm may be run just after the setting.
2193 	 */
2194 	if (dm_table_request_based(t) && !blk_queue_stopped(q))
2195 		stop_queue(q);
2196 
2197 	__bind_mempools(md, t);
2198 
2199 	merge_is_optional = dm_table_merge_is_optional(t);
2200 
2201 	old_map = md->map;
2202 	rcu_assign_pointer(md->map, t);
2203 	md->immutable_target_type = dm_table_get_immutable_target_type(t);
2204 
2205 	dm_table_set_restrictions(t, q, limits);
2206 	if (merge_is_optional)
2207 		set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
2208 	else
2209 		clear_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
2210 	dm_sync_table(md);
2211 
2212 	return old_map;
2213 }
2214 
2215 /*
2216  * Returns unbound table for the caller to free.
2217  */
2218 static struct dm_table *__unbind(struct mapped_device *md)
2219 {
2220 	struct dm_table *map = md->map;
2221 
2222 	if (!map)
2223 		return NULL;
2224 
2225 	dm_table_event_callback(map, NULL, NULL);
2226 	rcu_assign_pointer(md->map, NULL);
2227 	dm_sync_table(md);
2228 
2229 	return map;
2230 }
2231 
2232 /*
2233  * Constructor for a new device.
2234  */
2235 int dm_create(int minor, struct mapped_device **result)
2236 {
2237 	struct mapped_device *md;
2238 
2239 	md = alloc_dev(minor);
2240 	if (!md)
2241 		return -ENXIO;
2242 
2243 	dm_sysfs_init(md);
2244 
2245 	*result = md;
2246 	return 0;
2247 }
2248 
2249 /*
2250  * Functions to manage md->type.
2251  * All are required to hold md->type_lock.
2252  */
2253 void dm_lock_md_type(struct mapped_device *md)
2254 {
2255 	mutex_lock(&md->type_lock);
2256 }
2257 
2258 void dm_unlock_md_type(struct mapped_device *md)
2259 {
2260 	mutex_unlock(&md->type_lock);
2261 }
2262 
2263 void dm_set_md_type(struct mapped_device *md, unsigned type)
2264 {
2265 	BUG_ON(!mutex_is_locked(&md->type_lock));
2266 	md->type = type;
2267 }
2268 
2269 unsigned dm_get_md_type(struct mapped_device *md)
2270 {
2271 	BUG_ON(!mutex_is_locked(&md->type_lock));
2272 	return md->type;
2273 }
2274 
2275 struct target_type *dm_get_immutable_target_type(struct mapped_device *md)
2276 {
2277 	return md->immutable_target_type;
2278 }
2279 
2280 /*
2281  * Fully initialize a request-based queue (->elevator, ->request_fn, etc).
2282  */
2283 static int dm_init_request_based_queue(struct mapped_device *md)
2284 {
2285 	struct request_queue *q = NULL;
2286 
2287 	if (md->queue->elevator)
2288 		return 1;
2289 
2290 	/* Fully initialize the queue */
2291 	q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL);
2292 	if (!q)
2293 		return 0;
2294 
2295 	md->queue = q;
2296 	dm_init_md_queue(md);
2297 	blk_queue_softirq_done(md->queue, dm_softirq_done);
2298 	blk_queue_prep_rq(md->queue, dm_prep_fn);
2299 	blk_queue_lld_busy(md->queue, dm_lld_busy);
2300 
2301 	elv_register_queue(md->queue);
2302 
2303 	return 1;
2304 }
2305 
2306 /*
2307  * Setup the DM device's queue based on md's type
2308  */
2309 int dm_setup_md_queue(struct mapped_device *md)
2310 {
2311 	if ((dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) &&
2312 	    !dm_init_request_based_queue(md)) {
2313 		DMWARN("Cannot initialize queue for request-based mapped device");
2314 		return -EINVAL;
2315 	}
2316 
2317 	return 0;
2318 }
2319 
2320 static struct mapped_device *dm_find_md(dev_t dev)
2321 {
2322 	struct mapped_device *md;
2323 	unsigned minor = MINOR(dev);
2324 
2325 	if (MAJOR(dev) != _major || minor >= (1 << MINORBITS))
2326 		return NULL;
2327 
2328 	spin_lock(&_minor_lock);
2329 
2330 	md = idr_find(&_minor_idr, minor);
2331 	if (md && (md == MINOR_ALLOCED ||
2332 		   (MINOR(disk_devt(dm_disk(md))) != minor) ||
2333 		   dm_deleting_md(md) ||
2334 		   test_bit(DMF_FREEING, &md->flags))) {
2335 		md = NULL;
2336 		goto out;
2337 	}
2338 
2339 out:
2340 	spin_unlock(&_minor_lock);
2341 
2342 	return md;
2343 }
2344 
2345 struct mapped_device *dm_get_md(dev_t dev)
2346 {
2347 	struct mapped_device *md = dm_find_md(dev);
2348 
2349 	if (md)
2350 		dm_get(md);
2351 
2352 	return md;
2353 }
2354 EXPORT_SYMBOL_GPL(dm_get_md);
2355 
2356 void *dm_get_mdptr(struct mapped_device *md)
2357 {
2358 	return md->interface_ptr;
2359 }
2360 
2361 void dm_set_mdptr(struct mapped_device *md, void *ptr)
2362 {
2363 	md->interface_ptr = ptr;
2364 }
2365 
2366 void dm_get(struct mapped_device *md)
2367 {
2368 	atomic_inc(&md->holders);
2369 	BUG_ON(test_bit(DMF_FREEING, &md->flags));
2370 }
2371 
2372 const char *dm_device_name(struct mapped_device *md)
2373 {
2374 	return md->name;
2375 }
2376 EXPORT_SYMBOL_GPL(dm_device_name);
2377 
2378 static void __dm_destroy(struct mapped_device *md, bool wait)
2379 {
2380 	struct dm_table *map;
2381 	int srcu_idx;
2382 
2383 	might_sleep();
2384 
2385 	spin_lock(&_minor_lock);
2386 	map = dm_get_live_table(md, &srcu_idx);
2387 	idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md))));
2388 	set_bit(DMF_FREEING, &md->flags);
2389 	spin_unlock(&_minor_lock);
2390 
2391 	if (!dm_suspended_md(md)) {
2392 		dm_table_presuspend_targets(map);
2393 		dm_table_postsuspend_targets(map);
2394 	}
2395 
2396 	/* dm_put_live_table must be before msleep, otherwise deadlock is possible */
2397 	dm_put_live_table(md, srcu_idx);
2398 
2399 	/*
2400 	 * Rare, but there may be I/O requests still going to complete,
2401 	 * for example.  Wait for all references to disappear.
2402 	 * No one should increment the reference count of the mapped_device,
2403 	 * after the mapped_device state becomes DMF_FREEING.
2404 	 */
2405 	if (wait)
2406 		while (atomic_read(&md->holders))
2407 			msleep(1);
2408 	else if (atomic_read(&md->holders))
2409 		DMWARN("%s: Forcibly removing mapped_device still in use! (%d users)",
2410 		       dm_device_name(md), atomic_read(&md->holders));
2411 
2412 	dm_sysfs_exit(md);
2413 	dm_table_destroy(__unbind(md));
2414 	free_dev(md);
2415 }
2416 
2417 void dm_destroy(struct mapped_device *md)
2418 {
2419 	__dm_destroy(md, true);
2420 }
2421 
2422 void dm_destroy_immediate(struct mapped_device *md)
2423 {
2424 	__dm_destroy(md, false);
2425 }
2426 
2427 void dm_put(struct mapped_device *md)
2428 {
2429 	atomic_dec(&md->holders);
2430 }
2431 EXPORT_SYMBOL_GPL(dm_put);
2432 
2433 static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
2434 {
2435 	int r = 0;
2436 	DECLARE_WAITQUEUE(wait, current);
2437 
2438 	add_wait_queue(&md->wait, &wait);
2439 
2440 	while (1) {
2441 		set_current_state(interruptible);
2442 
2443 		if (!md_in_flight(md))
2444 			break;
2445 
2446 		if (interruptible == TASK_INTERRUPTIBLE &&
2447 		    signal_pending(current)) {
2448 			r = -EINTR;
2449 			break;
2450 		}
2451 
2452 		io_schedule();
2453 	}
2454 	set_current_state(TASK_RUNNING);
2455 
2456 	remove_wait_queue(&md->wait, &wait);
2457 
2458 	return r;
2459 }
2460 
2461 /*
2462  * Process the deferred bios
2463  */
2464 static void dm_wq_work(struct work_struct *work)
2465 {
2466 	struct mapped_device *md = container_of(work, struct mapped_device,
2467 						work);
2468 	struct bio *c;
2469 	int srcu_idx;
2470 	struct dm_table *map;
2471 
2472 	map = dm_get_live_table(md, &srcu_idx);
2473 
2474 	while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
2475 		spin_lock_irq(&md->deferred_lock);
2476 		c = bio_list_pop(&md->deferred);
2477 		spin_unlock_irq(&md->deferred_lock);
2478 
2479 		if (!c)
2480 			break;
2481 
2482 		if (dm_request_based(md))
2483 			generic_make_request(c);
2484 		else
2485 			__split_and_process_bio(md, map, c);
2486 	}
2487 
2488 	dm_put_live_table(md, srcu_idx);
2489 }
2490 
2491 static void dm_queue_flush(struct mapped_device *md)
2492 {
2493 	clear_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
2494 	smp_mb__after_clear_bit();
2495 	queue_work(md->wq, &md->work);
2496 }
2497 
2498 /*
2499  * Swap in a new table, returning the old one for the caller to destroy.
2500  */
2501 struct dm_table *dm_swap_table(struct mapped_device *md, struct dm_table *table)
2502 {
2503 	struct dm_table *live_map = NULL, *map = ERR_PTR(-EINVAL);
2504 	struct queue_limits limits;
2505 	int r;
2506 
2507 	mutex_lock(&md->suspend_lock);
2508 
2509 	/* device must be suspended */
2510 	if (!dm_suspended_md(md))
2511 		goto out;
2512 
2513 	/*
2514 	 * If the new table has no data devices, retain the existing limits.
2515 	 * This helps multipath with queue_if_no_path if all paths disappear,
2516 	 * then new I/O is queued based on these limits, and then some paths
2517 	 * reappear.
2518 	 */
2519 	if (dm_table_has_no_data_devices(table)) {
2520 		live_map = dm_get_live_table_fast(md);
2521 		if (live_map)
2522 			limits = md->queue->limits;
2523 		dm_put_live_table_fast(md);
2524 	}
2525 
2526 	if (!live_map) {
2527 		r = dm_calculate_queue_limits(table, &limits);
2528 		if (r) {
2529 			map = ERR_PTR(r);
2530 			goto out;
2531 		}
2532 	}
2533 
2534 	map = __bind(md, table, &limits);
2535 
2536 out:
2537 	mutex_unlock(&md->suspend_lock);
2538 	return map;
2539 }
2540 
2541 /*
2542  * Functions to lock and unlock any filesystem running on the
2543  * device.
2544  */
2545 static int lock_fs(struct mapped_device *md)
2546 {
2547 	int r;
2548 
2549 	WARN_ON(md->frozen_sb);
2550 
2551 	md->frozen_sb = freeze_bdev(md->bdev);
2552 	if (IS_ERR(md->frozen_sb)) {
2553 		r = PTR_ERR(md->frozen_sb);
2554 		md->frozen_sb = NULL;
2555 		return r;
2556 	}
2557 
2558 	set_bit(DMF_FROZEN, &md->flags);
2559 
2560 	return 0;
2561 }
2562 
2563 static void unlock_fs(struct mapped_device *md)
2564 {
2565 	if (!test_bit(DMF_FROZEN, &md->flags))
2566 		return;
2567 
2568 	thaw_bdev(md->bdev, md->frozen_sb);
2569 	md->frozen_sb = NULL;
2570 	clear_bit(DMF_FROZEN, &md->flags);
2571 }
2572 
2573 /*
2574  * We need to be able to change a mapping table under a mounted
2575  * filesystem.  For example we might want to move some data in
2576  * the background.  Before the table can be swapped with
2577  * dm_bind_table, dm_suspend must be called to flush any in
2578  * flight bios and ensure that any further io gets deferred.
2579  */
2580 /*
2581  * Suspend mechanism in request-based dm.
2582  *
2583  * 1. Flush all I/Os by lock_fs() if needed.
2584  * 2. Stop dispatching any I/O by stopping the request_queue.
2585  * 3. Wait for all in-flight I/Os to be completed or requeued.
2586  *
2587  * To abort suspend, start the request_queue.
2588  */
2589 int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
2590 {
2591 	struct dm_table *map = NULL;
2592 	int r = 0;
2593 	int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0;
2594 	int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0;
2595 
2596 	mutex_lock(&md->suspend_lock);
2597 
2598 	if (dm_suspended_md(md)) {
2599 		r = -EINVAL;
2600 		goto out_unlock;
2601 	}
2602 
2603 	map = md->map;
2604 
2605 	/*
2606 	 * DMF_NOFLUSH_SUSPENDING must be set before presuspend.
2607 	 * This flag is cleared before dm_suspend returns.
2608 	 */
2609 	if (noflush)
2610 		set_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
2611 
2612 	/* This does not get reverted if there's an error later. */
2613 	dm_table_presuspend_targets(map);
2614 
2615 	/*
2616 	 * Flush I/O to the device.
2617 	 * Any I/O submitted after lock_fs() may not be flushed.
2618 	 * noflush takes precedence over do_lockfs.
2619 	 * (lock_fs() flushes I/Os and waits for them to complete.)
2620 	 */
2621 	if (!noflush && do_lockfs) {
2622 		r = lock_fs(md);
2623 		if (r)
2624 			goto out_unlock;
2625 	}
2626 
2627 	/*
2628 	 * Here we must make sure that no processes are submitting requests
2629 	 * to target drivers i.e. no one may be executing
2630 	 * __split_and_process_bio. This is called from dm_request and
2631 	 * dm_wq_work.
2632 	 *
2633 	 * To get all processes out of __split_and_process_bio in dm_request,
2634 	 * we take the write lock. To prevent any process from reentering
2635 	 * __split_and_process_bio from dm_request and quiesce the thread
2636 	 * (dm_wq_work), we set BMF_BLOCK_IO_FOR_SUSPEND and call
2637 	 * flush_workqueue(md->wq).
2638 	 */
2639 	set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
2640 	synchronize_srcu(&md->io_barrier);
2641 
2642 	/*
2643 	 * Stop md->queue before flushing md->wq in case request-based
2644 	 * dm defers requests to md->wq from md->queue.
2645 	 */
2646 	if (dm_request_based(md))
2647 		stop_queue(md->queue);
2648 
2649 	flush_workqueue(md->wq);
2650 
2651 	/*
2652 	 * At this point no more requests are entering target request routines.
2653 	 * We call dm_wait_for_completion to wait for all existing requests
2654 	 * to finish.
2655 	 */
2656 	r = dm_wait_for_completion(md, TASK_INTERRUPTIBLE);
2657 
2658 	if (noflush)
2659 		clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
2660 	synchronize_srcu(&md->io_barrier);
2661 
2662 	/* were we interrupted ? */
2663 	if (r < 0) {
2664 		dm_queue_flush(md);
2665 
2666 		if (dm_request_based(md))
2667 			start_queue(md->queue);
2668 
2669 		unlock_fs(md);
2670 		goto out_unlock; /* pushback list is already flushed, so skip flush */
2671 	}
2672 
2673 	/*
2674 	 * If dm_wait_for_completion returned 0, the device is completely
2675 	 * quiescent now. There is no request-processing activity. All new
2676 	 * requests are being added to md->deferred list.
2677 	 */
2678 
2679 	set_bit(DMF_SUSPENDED, &md->flags);
2680 
2681 	dm_table_postsuspend_targets(map);
2682 
2683 out_unlock:
2684 	mutex_unlock(&md->suspend_lock);
2685 	return r;
2686 }
2687 
2688 int dm_resume(struct mapped_device *md)
2689 {
2690 	int r = -EINVAL;
2691 	struct dm_table *map = NULL;
2692 
2693 	mutex_lock(&md->suspend_lock);
2694 	if (!dm_suspended_md(md))
2695 		goto out;
2696 
2697 	map = md->map;
2698 	if (!map || !dm_table_get_size(map))
2699 		goto out;
2700 
2701 	r = dm_table_resume_targets(map);
2702 	if (r)
2703 		goto out;
2704 
2705 	dm_queue_flush(md);
2706 
2707 	/*
2708 	 * Flushing deferred I/Os must be done after targets are resumed
2709 	 * so that mapping of targets can work correctly.
2710 	 * Request-based dm is queueing the deferred I/Os in its request_queue.
2711 	 */
2712 	if (dm_request_based(md))
2713 		start_queue(md->queue);
2714 
2715 	unlock_fs(md);
2716 
2717 	clear_bit(DMF_SUSPENDED, &md->flags);
2718 
2719 	r = 0;
2720 out:
2721 	mutex_unlock(&md->suspend_lock);
2722 
2723 	return r;
2724 }
2725 
2726 /*
2727  * Internal suspend/resume works like userspace-driven suspend. It waits
2728  * until all bios finish and prevents issuing new bios to the target drivers.
2729  * It may be used only from the kernel.
2730  *
2731  * Internal suspend holds md->suspend_lock, which prevents interaction with
2732  * userspace-driven suspend.
2733  */
2734 
2735 void dm_internal_suspend(struct mapped_device *md)
2736 {
2737 	mutex_lock(&md->suspend_lock);
2738 	if (dm_suspended_md(md))
2739 		return;
2740 
2741 	set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
2742 	synchronize_srcu(&md->io_barrier);
2743 	flush_workqueue(md->wq);
2744 	dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
2745 }
2746 
2747 void dm_internal_resume(struct mapped_device *md)
2748 {
2749 	if (dm_suspended_md(md))
2750 		goto done;
2751 
2752 	dm_queue_flush(md);
2753 
2754 done:
2755 	mutex_unlock(&md->suspend_lock);
2756 }
2757 
2758 /*-----------------------------------------------------------------
2759  * Event notification.
2760  *---------------------------------------------------------------*/
2761 int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
2762 		       unsigned cookie)
2763 {
2764 	char udev_cookie[DM_COOKIE_LENGTH];
2765 	char *envp[] = { udev_cookie, NULL };
2766 
2767 	if (!cookie)
2768 		return kobject_uevent(&disk_to_dev(md->disk)->kobj, action);
2769 	else {
2770 		snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u",
2771 			 DM_COOKIE_ENV_VAR_NAME, cookie);
2772 		return kobject_uevent_env(&disk_to_dev(md->disk)->kobj,
2773 					  action, envp);
2774 	}
2775 }
2776 
2777 uint32_t dm_next_uevent_seq(struct mapped_device *md)
2778 {
2779 	return atomic_add_return(1, &md->uevent_seq);
2780 }
2781 
2782 uint32_t dm_get_event_nr(struct mapped_device *md)
2783 {
2784 	return atomic_read(&md->event_nr);
2785 }
2786 
2787 int dm_wait_event(struct mapped_device *md, int event_nr)
2788 {
2789 	return wait_event_interruptible(md->eventq,
2790 			(event_nr != atomic_read(&md->event_nr)));
2791 }
2792 
2793 void dm_uevent_add(struct mapped_device *md, struct list_head *elist)
2794 {
2795 	unsigned long flags;
2796 
2797 	spin_lock_irqsave(&md->uevent_lock, flags);
2798 	list_add(elist, &md->uevent_list);
2799 	spin_unlock_irqrestore(&md->uevent_lock, flags);
2800 }
2801 
2802 /*
2803  * The gendisk is only valid as long as you have a reference
2804  * count on 'md'.
2805  */
2806 struct gendisk *dm_disk(struct mapped_device *md)
2807 {
2808 	return md->disk;
2809 }
2810 
2811 struct kobject *dm_kobject(struct mapped_device *md)
2812 {
2813 	return &md->kobj;
2814 }
2815 
2816 /*
2817  * struct mapped_device should not be exported outside of dm.c
2818  * so use this check to verify that kobj is part of md structure
2819  */
2820 struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
2821 {
2822 	struct mapped_device *md;
2823 
2824 	md = container_of(kobj, struct mapped_device, kobj);
2825 	if (&md->kobj != kobj)
2826 		return NULL;
2827 
2828 	if (test_bit(DMF_FREEING, &md->flags) ||
2829 	    dm_deleting_md(md))
2830 		return NULL;
2831 
2832 	dm_get(md);
2833 	return md;
2834 }
2835 
2836 int dm_suspended_md(struct mapped_device *md)
2837 {
2838 	return test_bit(DMF_SUSPENDED, &md->flags);
2839 }
2840 
2841 int dm_suspended(struct dm_target *ti)
2842 {
2843 	return dm_suspended_md(dm_table_get_md(ti->table));
2844 }
2845 EXPORT_SYMBOL_GPL(dm_suspended);
2846 
2847 int dm_noflush_suspending(struct dm_target *ti)
2848 {
2849 	return __noflush_suspending(dm_table_get_md(ti->table));
2850 }
2851 EXPORT_SYMBOL_GPL(dm_noflush_suspending);
2852 
2853 struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, unsigned per_bio_data_size)
2854 {
2855 	struct dm_md_mempools *pools = kzalloc(sizeof(*pools), GFP_KERNEL);
2856 	struct kmem_cache *cachep;
2857 	unsigned int pool_size;
2858 	unsigned int front_pad;
2859 
2860 	if (!pools)
2861 		return NULL;
2862 
2863 	if (type == DM_TYPE_BIO_BASED) {
2864 		cachep = _io_cache;
2865 		pool_size = 16;
2866 		front_pad = roundup(per_bio_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone);
2867 	} else if (type == DM_TYPE_REQUEST_BASED) {
2868 		cachep = _rq_tio_cache;
2869 		pool_size = MIN_IOS;
2870 		front_pad = offsetof(struct dm_rq_clone_bio_info, clone);
2871 		/* per_bio_data_size is not used. See __bind_mempools(). */
2872 		WARN_ON(per_bio_data_size != 0);
2873 	} else
2874 		goto out;
2875 
2876 	pools->io_pool = mempool_create_slab_pool(MIN_IOS, cachep);
2877 	if (!pools->io_pool)
2878 		goto out;
2879 
2880 	pools->bs = bioset_create(pool_size, front_pad);
2881 	if (!pools->bs)
2882 		goto out;
2883 
2884 	if (integrity && bioset_integrity_create(pools->bs, pool_size))
2885 		goto out;
2886 
2887 	return pools;
2888 
2889 out:
2890 	dm_free_md_mempools(pools);
2891 
2892 	return NULL;
2893 }
2894 
2895 void dm_free_md_mempools(struct dm_md_mempools *pools)
2896 {
2897 	if (!pools)
2898 		return;
2899 
2900 	if (pools->io_pool)
2901 		mempool_destroy(pools->io_pool);
2902 
2903 	if (pools->bs)
2904 		bioset_free(pools->bs);
2905 
2906 	kfree(pools);
2907 }
2908 
2909 static const struct block_device_operations dm_blk_dops = {
2910 	.open = dm_blk_open,
2911 	.release = dm_blk_close,
2912 	.ioctl = dm_blk_ioctl,
2913 	.getgeo = dm_blk_getgeo,
2914 	.owner = THIS_MODULE
2915 };
2916 
2917 EXPORT_SYMBOL(dm_get_mapinfo);
2918 
2919 /*
2920  * module hooks
2921  */
2922 module_init(dm_init);
2923 module_exit(dm_exit);
2924 
2925 module_param(major, uint, 0);
2926 MODULE_PARM_DESC(major, "The major number of the device mapper");
2927 MODULE_DESCRIPTION(DM_NAME " driver");
2928 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
2929 MODULE_LICENSE("GPL");
2930