blob: bb3ad79c14d7deeabce18c00577f8add278ab51b [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
3 * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8#include "dm.h"
9#include "dm-bio-list.h"
10
11#include <linux/init.h>
12#include <linux/module.h>
13#include <linux/moduleparam.h>
14#include <linux/blkpg.h>
15#include <linux/bio.h>
16#include <linux/buffer_head.h>
17#include <linux/mempool.h>
18#include <linux/slab.h>
19#include <linux/idr.h>
20
21static const char *_name = DM_NAME;
22
23static unsigned int major = 0;
24static unsigned int _major = 0;
25
26/*
27 * One of these is allocated per bio.
28 */
29struct dm_io {
30 struct mapped_device *md;
31 int error;
32 struct bio *bio;
33 atomic_t io_count;
34};
35
36/*
37 * One of these is allocated per target within a bio. Hopefully
38 * this will be simplified out one day.
39 */
40struct target_io {
41 struct dm_io *io;
42 struct dm_target *ti;
43 union map_info info;
44};
45
46union map_info *dm_get_mapinfo(struct bio *bio)
47{
48 if (bio && bio->bi_private)
49 return &((struct target_io *)bio->bi_private)->info;
50 return NULL;
51}
52
53/*
54 * Bits for the md->flags field.
55 */
56#define DMF_BLOCK_IO 0
57#define DMF_SUSPENDED 1
58#define DMF_FS_LOCKED 2
59
60struct mapped_device {
61 struct rw_semaphore lock;
62 rwlock_t map_lock;
63 atomic_t holders;
64
65 unsigned long flags;
66
67 request_queue_t *queue;
68 struct gendisk *disk;
69
70 void *interface_ptr;
71
72 /*
73 * A list of ios that arrived while we were suspended.
74 */
75 atomic_t pending;
76 wait_queue_head_t wait;
77 struct bio_list deferred;
78
79 /*
80 * The current mapping.
81 */
82 struct dm_table *map;
83
84 /*
85 * io objects are allocated from here.
86 */
87 mempool_t *io_pool;
88 mempool_t *tio_pool;
89
90 /*
91 * Event handling.
92 */
93 atomic_t event_nr;
94 wait_queue_head_t eventq;
95
96 /*
97 * freeze/thaw support require holding onto a super block
98 */
99 struct super_block *frozen_sb;
Alasdair G Kergond1782a32005-05-05 16:16:03 -0700100 struct block_device *frozen_bdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101};
102
103#define MIN_IOS 256
104static kmem_cache_t *_io_cache;
105static kmem_cache_t *_tio_cache;
106
107static struct bio_set *dm_set;
108
109static int __init local_init(void)
110{
111 int r;
112
113 dm_set = bioset_create(16, 16, 4);
114 if (!dm_set)
115 return -ENOMEM;
116
117 /* allocate a slab for the dm_ios */
118 _io_cache = kmem_cache_create("dm_io",
119 sizeof(struct dm_io), 0, 0, NULL, NULL);
120 if (!_io_cache)
121 return -ENOMEM;
122
123 /* allocate a slab for the target ios */
124 _tio_cache = kmem_cache_create("dm_tio", sizeof(struct target_io),
125 0, 0, NULL, NULL);
126 if (!_tio_cache) {
127 kmem_cache_destroy(_io_cache);
128 return -ENOMEM;
129 }
130
131 _major = major;
132 r = register_blkdev(_major, _name);
133 if (r < 0) {
134 kmem_cache_destroy(_tio_cache);
135 kmem_cache_destroy(_io_cache);
136 return r;
137 }
138
139 if (!_major)
140 _major = r;
141
142 return 0;
143}
144
145static void local_exit(void)
146{
147 kmem_cache_destroy(_tio_cache);
148 kmem_cache_destroy(_io_cache);
149
150 bioset_free(dm_set);
151
152 if (unregister_blkdev(_major, _name) < 0)
153 DMERR("devfs_unregister_blkdev failed");
154
155 _major = 0;
156
157 DMINFO("cleaned up");
158}
159
160int (*_inits[])(void) __initdata = {
161 local_init,
162 dm_target_init,
163 dm_linear_init,
164 dm_stripe_init,
165 dm_interface_init,
166};
167
168void (*_exits[])(void) = {
169 local_exit,
170 dm_target_exit,
171 dm_linear_exit,
172 dm_stripe_exit,
173 dm_interface_exit,
174};
175
176static int __init dm_init(void)
177{
178 const int count = ARRAY_SIZE(_inits);
179
180 int r, i;
181
182 for (i = 0; i < count; i++) {
183 r = _inits[i]();
184 if (r)
185 goto bad;
186 }
187
188 return 0;
189
190 bad:
191 while (i--)
192 _exits[i]();
193
194 return r;
195}
196
197static void __exit dm_exit(void)
198{
199 int i = ARRAY_SIZE(_exits);
200
201 while (i--)
202 _exits[i]();
203}
204
205/*
206 * Block device functions
207 */
208static int dm_blk_open(struct inode *inode, struct file *file)
209{
210 struct mapped_device *md;
211
212 md = inode->i_bdev->bd_disk->private_data;
213 dm_get(md);
214 return 0;
215}
216
217static int dm_blk_close(struct inode *inode, struct file *file)
218{
219 struct mapped_device *md;
220
221 md = inode->i_bdev->bd_disk->private_data;
222 dm_put(md);
223 return 0;
224}
225
226static inline struct dm_io *alloc_io(struct mapped_device *md)
227{
228 return mempool_alloc(md->io_pool, GFP_NOIO);
229}
230
231static inline void free_io(struct mapped_device *md, struct dm_io *io)
232{
233 mempool_free(io, md->io_pool);
234}
235
236static inline struct target_io *alloc_tio(struct mapped_device *md)
237{
238 return mempool_alloc(md->tio_pool, GFP_NOIO);
239}
240
241static inline void free_tio(struct mapped_device *md, struct target_io *tio)
242{
243 mempool_free(tio, md->tio_pool);
244}
245
246/*
247 * Add the bio to the list of deferred io.
248 */
249static int queue_io(struct mapped_device *md, struct bio *bio)
250{
251 down_write(&md->lock);
252
253 if (!test_bit(DMF_BLOCK_IO, &md->flags)) {
254 up_write(&md->lock);
255 return 1;
256 }
257
258 bio_list_add(&md->deferred, bio);
259
260 up_write(&md->lock);
261 return 0; /* deferred successfully */
262}
263
264/*
265 * Everyone (including functions in this file), should use this
266 * function to access the md->map field, and make sure they call
267 * dm_table_put() when finished.
268 */
269struct dm_table *dm_get_table(struct mapped_device *md)
270{
271 struct dm_table *t;
272
273 read_lock(&md->map_lock);
274 t = md->map;
275 if (t)
276 dm_table_get(t);
277 read_unlock(&md->map_lock);
278
279 return t;
280}
281
282/*-----------------------------------------------------------------
283 * CRUD START:
284 * A more elegant soln is in the works that uses the queue
285 * merge fn, unfortunately there are a couple of changes to
286 * the block layer that I want to make for this. So in the
287 * interests of getting something for people to use I give
288 * you this clearly demarcated crap.
289 *---------------------------------------------------------------*/
290
291/*
292 * Decrements the number of outstanding ios that a bio has been
293 * cloned into, completing the original io if necc.
294 */
295static inline void dec_pending(struct dm_io *io, int error)
296{
297 if (error)
298 io->error = error;
299
300 if (atomic_dec_and_test(&io->io_count)) {
301 if (atomic_dec_and_test(&io->md->pending))
302 /* nudge anyone waiting on suspend queue */
303 wake_up(&io->md->wait);
304
305 bio_endio(io->bio, io->bio->bi_size, io->error);
306 free_io(io->md, io);
307 }
308}
309
310static int clone_endio(struct bio *bio, unsigned int done, int error)
311{
312 int r = 0;
313 struct target_io *tio = bio->bi_private;
314 struct dm_io *io = tio->io;
315 dm_endio_fn endio = tio->ti->type->end_io;
316
317 if (bio->bi_size)
318 return 1;
319
320 if (!bio_flagged(bio, BIO_UPTODATE) && !error)
321 error = -EIO;
322
323 if (endio) {
324 r = endio(tio->ti, bio, error, &tio->info);
325 if (r < 0)
326 error = r;
327
328 else if (r > 0)
329 /* the target wants another shot at the io */
330 return 1;
331 }
332
333 free_tio(io->md, tio);
334 dec_pending(io, error);
335 bio_put(bio);
336 return r;
337}
338
339static sector_t max_io_len(struct mapped_device *md,
340 sector_t sector, struct dm_target *ti)
341{
342 sector_t offset = sector - ti->begin;
343 sector_t len = ti->len - offset;
344
345 /*
346 * Does the target need to split even further ?
347 */
348 if (ti->split_io) {
349 sector_t boundary;
350 boundary = ((offset + ti->split_io) & ~(ti->split_io - 1))
351 - offset;
352 if (len > boundary)
353 len = boundary;
354 }
355
356 return len;
357}
358
359static void __map_bio(struct dm_target *ti, struct bio *clone,
360 struct target_io *tio)
361{
362 int r;
363
364 /*
365 * Sanity checks.
366 */
367 BUG_ON(!clone->bi_size);
368
369 clone->bi_end_io = clone_endio;
370 clone->bi_private = tio;
371
372 /*
373 * Map the clone. If r == 0 we don't need to do
374 * anything, the target has assumed ownership of
375 * this io.
376 */
377 atomic_inc(&tio->io->io_count);
378 r = ti->type->map(ti, clone, &tio->info);
379 if (r > 0)
380 /* the bio has been remapped so dispatch it */
381 generic_make_request(clone);
382
383 else if (r < 0) {
384 /* error the io and bail out */
385 struct dm_io *io = tio->io;
386 free_tio(tio->io->md, tio);
Alasdair G Kergonf6a80ea2005-07-12 15:53:01 -0700387 dec_pending(io, r);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 bio_put(clone);
389 }
390}
391
392struct clone_info {
393 struct mapped_device *md;
394 struct dm_table *map;
395 struct bio *bio;
396 struct dm_io *io;
397 sector_t sector;
398 sector_t sector_count;
399 unsigned short idx;
400};
401
402/*
403 * Creates a little bio that is just does part of a bvec.
404 */
405static struct bio *split_bvec(struct bio *bio, sector_t sector,
406 unsigned short idx, unsigned int offset,
407 unsigned int len)
408{
409 struct bio *clone;
410 struct bio_vec *bv = bio->bi_io_vec + idx;
411
412 clone = bio_alloc_bioset(GFP_NOIO, 1, dm_set);
413 *clone->bi_io_vec = *bv;
414
415 clone->bi_sector = sector;
416 clone->bi_bdev = bio->bi_bdev;
417 clone->bi_rw = bio->bi_rw;
418 clone->bi_vcnt = 1;
419 clone->bi_size = to_bytes(len);
420 clone->bi_io_vec->bv_offset = offset;
421 clone->bi_io_vec->bv_len = clone->bi_size;
422
423 return clone;
424}
425
426/*
427 * Creates a bio that consists of range of complete bvecs.
428 */
429static struct bio *clone_bio(struct bio *bio, sector_t sector,
430 unsigned short idx, unsigned short bv_count,
431 unsigned int len)
432{
433 struct bio *clone;
434
435 clone = bio_clone(bio, GFP_NOIO);
436 clone->bi_sector = sector;
437 clone->bi_idx = idx;
438 clone->bi_vcnt = idx + bv_count;
439 clone->bi_size = to_bytes(len);
440 clone->bi_flags &= ~(1 << BIO_SEG_VALID);
441
442 return clone;
443}
444
445static void __clone_and_map(struct clone_info *ci)
446{
447 struct bio *clone, *bio = ci->bio;
448 struct dm_target *ti = dm_table_find_target(ci->map, ci->sector);
449 sector_t len = 0, max = max_io_len(ci->md, ci->sector, ti);
450 struct target_io *tio;
451
452 /*
453 * Allocate a target io object.
454 */
455 tio = alloc_tio(ci->md);
456 tio->io = ci->io;
457 tio->ti = ti;
458 memset(&tio->info, 0, sizeof(tio->info));
459
460 if (ci->sector_count <= max) {
461 /*
462 * Optimise for the simple case where we can do all of
463 * the remaining io with a single clone.
464 */
465 clone = clone_bio(bio, ci->sector, ci->idx,
466 bio->bi_vcnt - ci->idx, ci->sector_count);
467 __map_bio(ti, clone, tio);
468 ci->sector_count = 0;
469
470 } else if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) {
471 /*
472 * There are some bvecs that don't span targets.
473 * Do as many of these as possible.
474 */
475 int i;
476 sector_t remaining = max;
477 sector_t bv_len;
478
479 for (i = ci->idx; remaining && (i < bio->bi_vcnt); i++) {
480 bv_len = to_sector(bio->bi_io_vec[i].bv_len);
481
482 if (bv_len > remaining)
483 break;
484
485 remaining -= bv_len;
486 len += bv_len;
487 }
488
489 clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len);
490 __map_bio(ti, clone, tio);
491
492 ci->sector += len;
493 ci->sector_count -= len;
494 ci->idx = i;
495
496 } else {
497 /*
498 * Create two copy bios to deal with io that has
499 * been split across a target.
500 */
501 struct bio_vec *bv = bio->bi_io_vec + ci->idx;
502
503 clone = split_bvec(bio, ci->sector, ci->idx,
504 bv->bv_offset, max);
505 __map_bio(ti, clone, tio);
506
507 ci->sector += max;
508 ci->sector_count -= max;
509 ti = dm_table_find_target(ci->map, ci->sector);
510
511 len = to_sector(bv->bv_len) - max;
512 clone = split_bvec(bio, ci->sector, ci->idx,
513 bv->bv_offset + to_bytes(max), len);
514 tio = alloc_tio(ci->md);
515 tio->io = ci->io;
516 tio->ti = ti;
517 memset(&tio->info, 0, sizeof(tio->info));
518 __map_bio(ti, clone, tio);
519
520 ci->sector += len;
521 ci->sector_count -= len;
522 ci->idx++;
523 }
524}
525
526/*
527 * Split the bio into several clones.
528 */
529static void __split_bio(struct mapped_device *md, struct bio *bio)
530{
531 struct clone_info ci;
532
533 ci.map = dm_get_table(md);
534 if (!ci.map) {
535 bio_io_error(bio, bio->bi_size);
536 return;
537 }
538
539 ci.md = md;
540 ci.bio = bio;
541 ci.io = alloc_io(md);
542 ci.io->error = 0;
543 atomic_set(&ci.io->io_count, 1);
544 ci.io->bio = bio;
545 ci.io->md = md;
546 ci.sector = bio->bi_sector;
547 ci.sector_count = bio_sectors(bio);
548 ci.idx = bio->bi_idx;
549
550 atomic_inc(&md->pending);
551 while (ci.sector_count)
552 __clone_and_map(&ci);
553
554 /* drop the extra reference count */
555 dec_pending(ci.io, 0);
556 dm_table_put(ci.map);
557}
558/*-----------------------------------------------------------------
559 * CRUD END
560 *---------------------------------------------------------------*/
561
562/*
563 * The request function that just remaps the bio built up by
564 * dm_merge_bvec.
565 */
566static int dm_request(request_queue_t *q, struct bio *bio)
567{
568 int r;
569 struct mapped_device *md = q->queuedata;
570
571 down_read(&md->lock);
572
573 /*
574 * If we're suspended we have to queue
575 * this io for later.
576 */
577 while (test_bit(DMF_BLOCK_IO, &md->flags)) {
578 up_read(&md->lock);
579
580 if (bio_rw(bio) == READA) {
581 bio_io_error(bio, bio->bi_size);
582 return 0;
583 }
584
585 r = queue_io(md, bio);
586 if (r < 0) {
587 bio_io_error(bio, bio->bi_size);
588 return 0;
589
590 } else if (r == 0)
591 return 0; /* deferred successfully */
592
593 /*
594 * We're in a while loop, because someone could suspend
595 * before we get to the following read lock.
596 */
597 down_read(&md->lock);
598 }
599
600 __split_bio(md, bio);
601 up_read(&md->lock);
602 return 0;
603}
604
605static int dm_flush_all(request_queue_t *q, struct gendisk *disk,
606 sector_t *error_sector)
607{
608 struct mapped_device *md = q->queuedata;
609 struct dm_table *map = dm_get_table(md);
610 int ret = -ENXIO;
611
612 if (map) {
613 ret = dm_table_flush_all(md->map);
614 dm_table_put(map);
615 }
616
617 return ret;
618}
619
620static void dm_unplug_all(request_queue_t *q)
621{
622 struct mapped_device *md = q->queuedata;
623 struct dm_table *map = dm_get_table(md);
624
625 if (map) {
626 dm_table_unplug_all(map);
627 dm_table_put(map);
628 }
629}
630
631static int dm_any_congested(void *congested_data, int bdi_bits)
632{
633 int r;
634 struct mapped_device *md = (struct mapped_device *) congested_data;
635 struct dm_table *map = dm_get_table(md);
636
637 if (!map || test_bit(DMF_BLOCK_IO, &md->flags))
638 r = bdi_bits;
639 else
640 r = dm_table_any_congested(map, bdi_bits);
641
642 dm_table_put(map);
643 return r;
644}
645
646/*-----------------------------------------------------------------
647 * An IDR is used to keep track of allocated minor numbers.
648 *---------------------------------------------------------------*/
649static DECLARE_MUTEX(_minor_lock);
650static DEFINE_IDR(_minor_idr);
651
652static void free_minor(unsigned int minor)
653{
654 down(&_minor_lock);
655 idr_remove(&_minor_idr, minor);
656 up(&_minor_lock);
657}
658
659/*
660 * See if the device with a specific minor # is free.
661 */
662static int specific_minor(struct mapped_device *md, unsigned int minor)
663{
664 int r, m;
665
666 if (minor >= (1 << MINORBITS))
667 return -EINVAL;
668
669 down(&_minor_lock);
670
671 if (idr_find(&_minor_idr, minor)) {
672 r = -EBUSY;
673 goto out;
674 }
675
676 r = idr_pre_get(&_minor_idr, GFP_KERNEL);
677 if (!r) {
678 r = -ENOMEM;
679 goto out;
680 }
681
682 r = idr_get_new_above(&_minor_idr, md, minor, &m);
683 if (r) {
684 goto out;
685 }
686
687 if (m != minor) {
688 idr_remove(&_minor_idr, m);
689 r = -EBUSY;
690 goto out;
691 }
692
693out:
694 up(&_minor_lock);
695 return r;
696}
697
698static int next_free_minor(struct mapped_device *md, unsigned int *minor)
699{
700 int r;
701 unsigned int m;
702
703 down(&_minor_lock);
704
705 r = idr_pre_get(&_minor_idr, GFP_KERNEL);
706 if (!r) {
707 r = -ENOMEM;
708 goto out;
709 }
710
711 r = idr_get_new(&_minor_idr, md, &m);
712 if (r) {
713 goto out;
714 }
715
716 if (m >= (1 << MINORBITS)) {
717 idr_remove(&_minor_idr, m);
718 r = -ENOSPC;
719 goto out;
720 }
721
722 *minor = m;
723
724out:
725 up(&_minor_lock);
726 return r;
727}
728
729static struct block_device_operations dm_blk_dops;
730
731/*
732 * Allocate and initialise a blank device with a given minor.
733 */
734static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
735{
736 int r;
737 struct mapped_device *md = kmalloc(sizeof(*md), GFP_KERNEL);
738
739 if (!md) {
740 DMWARN("unable to allocate device, out of memory.");
741 return NULL;
742 }
743
744 /* get a minor number for the dev */
745 r = persistent ? specific_minor(md, minor) : next_free_minor(md, &minor);
746 if (r < 0)
747 goto bad1;
748
749 memset(md, 0, sizeof(*md));
750 init_rwsem(&md->lock);
751 rwlock_init(&md->map_lock);
752 atomic_set(&md->holders, 1);
753 atomic_set(&md->event_nr, 0);
754
755 md->queue = blk_alloc_queue(GFP_KERNEL);
756 if (!md->queue)
757 goto bad1;
758
759 md->queue->queuedata = md;
760 md->queue->backing_dev_info.congested_fn = dm_any_congested;
761 md->queue->backing_dev_info.congested_data = md;
762 blk_queue_make_request(md->queue, dm_request);
763 md->queue->unplug_fn = dm_unplug_all;
764 md->queue->issue_flush_fn = dm_flush_all;
765
766 md->io_pool = mempool_create(MIN_IOS, mempool_alloc_slab,
767 mempool_free_slab, _io_cache);
768 if (!md->io_pool)
769 goto bad2;
770
771 md->tio_pool = mempool_create(MIN_IOS, mempool_alloc_slab,
772 mempool_free_slab, _tio_cache);
773 if (!md->tio_pool)
774 goto bad3;
775
776 md->disk = alloc_disk(1);
777 if (!md->disk)
778 goto bad4;
779
780 md->disk->major = _major;
781 md->disk->first_minor = minor;
782 md->disk->fops = &dm_blk_dops;
783 md->disk->queue = md->queue;
784 md->disk->private_data = md;
785 sprintf(md->disk->disk_name, "dm-%d", minor);
786 add_disk(md->disk);
787
788 atomic_set(&md->pending, 0);
789 init_waitqueue_head(&md->wait);
790 init_waitqueue_head(&md->eventq);
791
792 return md;
793
794 bad4:
795 mempool_destroy(md->tio_pool);
796 bad3:
797 mempool_destroy(md->io_pool);
798 bad2:
799 blk_put_queue(md->queue);
800 free_minor(minor);
801 bad1:
802 kfree(md);
803 return NULL;
804}
805
806static void free_dev(struct mapped_device *md)
807{
808 free_minor(md->disk->first_minor);
809 mempool_destroy(md->tio_pool);
810 mempool_destroy(md->io_pool);
811 del_gendisk(md->disk);
812 put_disk(md->disk);
813 blk_put_queue(md->queue);
814 kfree(md);
815}
816
817/*
818 * Bind a table to the device.
819 */
820static void event_callback(void *context)
821{
822 struct mapped_device *md = (struct mapped_device *) context;
823
824 atomic_inc(&md->event_nr);
825 wake_up(&md->eventq);
826}
827
828static void __set_size(struct gendisk *disk, sector_t size)
829{
830 struct block_device *bdev;
831
832 set_capacity(disk, size);
833 bdev = bdget_disk(disk, 0);
834 if (bdev) {
835 down(&bdev->bd_inode->i_sem);
836 i_size_write(bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
837 up(&bdev->bd_inode->i_sem);
838 bdput(bdev);
839 }
840}
841
842static int __bind(struct mapped_device *md, struct dm_table *t)
843{
844 request_queue_t *q = md->queue;
845 sector_t size;
846
847 size = dm_table_get_size(t);
848 __set_size(md->disk, size);
849 if (size == 0)
850 return 0;
851
852 write_lock(&md->map_lock);
853 md->map = t;
854 write_unlock(&md->map_lock);
855
856 dm_table_get(t);
857 dm_table_event_callback(md->map, event_callback, md);
858 dm_table_set_restrictions(t, q);
859 return 0;
860}
861
862static void __unbind(struct mapped_device *md)
863{
864 struct dm_table *map = md->map;
865
866 if (!map)
867 return;
868
869 dm_table_event_callback(map, NULL, NULL);
870 write_lock(&md->map_lock);
871 md->map = NULL;
872 write_unlock(&md->map_lock);
873 dm_table_put(map);
874}
875
876/*
877 * Constructor for a new device.
878 */
879static int create_aux(unsigned int minor, int persistent,
880 struct mapped_device **result)
881{
882 struct mapped_device *md;
883
884 md = alloc_dev(minor, persistent);
885 if (!md)
886 return -ENXIO;
887
888 *result = md;
889 return 0;
890}
891
892int dm_create(struct mapped_device **result)
893{
894 return create_aux(0, 0, result);
895}
896
897int dm_create_with_minor(unsigned int minor, struct mapped_device **result)
898{
899 return create_aux(minor, 1, result);
900}
901
902void *dm_get_mdptr(dev_t dev)
903{
904 struct mapped_device *md;
905 void *mdptr = NULL;
906 unsigned minor = MINOR(dev);
907
908 if (MAJOR(dev) != _major || minor >= (1 << MINORBITS))
909 return NULL;
910
911 down(&_minor_lock);
912
913 md = idr_find(&_minor_idr, minor);
914
915 if (md && (dm_disk(md)->first_minor == minor))
916 mdptr = md->interface_ptr;
917
918 up(&_minor_lock);
919
920 return mdptr;
921}
922
923void dm_set_mdptr(struct mapped_device *md, void *ptr)
924{
925 md->interface_ptr = ptr;
926}
927
928void dm_get(struct mapped_device *md)
929{
930 atomic_inc(&md->holders);
931}
932
933void dm_put(struct mapped_device *md)
934{
935 struct dm_table *map = dm_get_table(md);
936
937 if (atomic_dec_and_test(&md->holders)) {
938 if (!test_bit(DMF_SUSPENDED, &md->flags) && map) {
939 dm_table_presuspend_targets(map);
940 dm_table_postsuspend_targets(map);
941 }
942 __unbind(md);
943 free_dev(md);
944 }
945
946 dm_table_put(map);
947}
948
949/*
950 * Process the deferred bios
951 */
952static void __flush_deferred_io(struct mapped_device *md, struct bio *c)
953{
954 struct bio *n;
955
956 while (c) {
957 n = c->bi_next;
958 c->bi_next = NULL;
959 __split_bio(md, c);
960 c = n;
961 }
962}
963
964/*
965 * Swap in a new table (destroying old one).
966 */
967int dm_swap_table(struct mapped_device *md, struct dm_table *table)
968{
969 int r;
970
971 down_write(&md->lock);
972
973 /* device must be suspended */
974 if (!test_bit(DMF_SUSPENDED, &md->flags)) {
975 up_write(&md->lock);
976 return -EPERM;
977 }
978
979 __unbind(md);
980 r = __bind(md, table);
981 if (r)
982 return r;
983
984 up_write(&md->lock);
985 return 0;
986}
987
988/*
989 * Functions to lock and unlock any filesystem running on the
990 * device.
991 */
992static int __lock_fs(struct mapped_device *md)
993{
Alasdair G Kergondfbe03f2005-05-05 16:16:04 -0700994 int error = -ENOMEM;
995
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996 if (test_and_set_bit(DMF_FS_LOCKED, &md->flags))
997 return 0;
998
Alasdair G Kergond1782a32005-05-05 16:16:03 -0700999 md->frozen_bdev = bdget_disk(md->disk, 0);
1000 if (!md->frozen_bdev) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001 DMWARN("bdget failed in __lock_fs");
Alasdair G Kergondfbe03f2005-05-05 16:16:04 -07001002 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 }
1004
1005 WARN_ON(md->frozen_sb);
Alasdair G Kergondfbe03f2005-05-05 16:16:04 -07001006
Alasdair G Kergond1782a32005-05-05 16:16:03 -07001007 md->frozen_sb = freeze_bdev(md->frozen_bdev);
Alasdair G Kergondfbe03f2005-05-05 16:16:04 -07001008 if (IS_ERR(md->frozen_sb)) {
1009 error = PTR_ERR(md->frozen_sb);
1010 goto out_bdput;
1011 }
1012
Linus Torvalds1da177e2005-04-16 15:20:36 -07001013 /* don't bdput right now, we don't want the bdev
1014 * to go away while it is locked. We'll bdput
1015 * in __unlock_fs
1016 */
1017 return 0;
Alasdair G Kergondfbe03f2005-05-05 16:16:04 -07001018
1019out_bdput:
1020 bdput(md->frozen_bdev);
1021 md->frozen_sb = NULL;
1022 md->frozen_bdev = NULL;
1023out:
1024 clear_bit(DMF_FS_LOCKED, &md->flags);
1025 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026}
1027
Alasdair G Kergon3dcee802005-05-05 16:16:04 -07001028static void __unlock_fs(struct mapped_device *md)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030 if (!test_and_clear_bit(DMF_FS_LOCKED, &md->flags))
Alasdair G Kergon3dcee802005-05-05 16:16:04 -07001031 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001032
Alasdair G Kergond1782a32005-05-05 16:16:03 -07001033 thaw_bdev(md->frozen_bdev, md->frozen_sb);
1034 bdput(md->frozen_bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035
Linus Torvalds1da177e2005-04-16 15:20:36 -07001036 md->frozen_sb = NULL;
Alasdair G Kergond1782a32005-05-05 16:16:03 -07001037 md->frozen_bdev = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038}
1039
1040/*
1041 * We need to be able to change a mapping table under a mounted
1042 * filesystem. For example we might want to move some data in
1043 * the background. Before the table can be swapped with
1044 * dm_bind_table, dm_suspend must be called to flush any in
1045 * flight bios and ensure that any further io gets deferred.
1046 */
1047int dm_suspend(struct mapped_device *md)
1048{
1049 struct dm_table *map;
1050 DECLARE_WAITQUEUE(wait, current);
Alasdair G Kergonb84b0282005-05-05 16:16:06 -07001051 int error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052
1053 /* Flush I/O to the device. */
1054 down_read(&md->lock);
Alasdair G Kergonb84b0282005-05-05 16:16:06 -07001055 if (test_bit(DMF_BLOCK_IO, &md->flags))
1056 goto out_read_unlock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057
1058 map = dm_get_table(md);
1059 if (map)
Alasdair G Kergon436d4102005-07-12 15:53:03 -07001060 /* This does not get reverted if there's an error later. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061 dm_table_presuspend_targets(map);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062
Alasdair G Kergon436d4102005-07-12 15:53:03 -07001063 error = __lock_fs(md);
1064 if (error) {
1065 dm_table_put(map);
1066 goto out_read_unlock;
1067 }
1068
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069 up_read(&md->lock);
1070
1071 /*
Alasdair G Kergon354e0072005-05-05 16:16:05 -07001072 * First we set the BLOCK_IO flag so no more ios will be mapped.
1073 *
1074 * If the flag is already set we know another thread is trying to
1075 * suspend as well, so we leave the fs locked for this thread.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001076 */
Alasdair G Kergonb84b0282005-05-05 16:16:06 -07001077 error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078 down_write(&md->lock);
Alasdair G Kergonb84b0282005-05-05 16:16:06 -07001079 if (test_and_set_bit(DMF_BLOCK_IO, &md->flags)) {
Alasdair G Kergon354e0072005-05-05 16:16:05 -07001080 if (map)
1081 dm_table_put(map);
Alasdair G Kergonb84b0282005-05-05 16:16:06 -07001082 goto out_write_unlock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083 }
1084
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085 add_wait_queue(&md->wait, &wait);
1086 up_write(&md->lock);
1087
1088 /* unplug */
1089 if (map) {
1090 dm_table_unplug_all(map);
1091 dm_table_put(map);
1092 }
1093
1094 /*
1095 * Then we wait for the already mapped ios to
1096 * complete.
1097 */
1098 while (1) {
1099 set_current_state(TASK_INTERRUPTIBLE);
1100
1101 if (!atomic_read(&md->pending) || signal_pending(current))
1102 break;
1103
1104 io_schedule();
1105 }
1106 set_current_state(TASK_RUNNING);
1107
1108 down_write(&md->lock);
1109 remove_wait_queue(&md->wait, &wait);
1110
1111 /* were we interrupted ? */
Alasdair G Kergonb84b0282005-05-05 16:16:06 -07001112 error = -EINTR;
1113 if (atomic_read(&md->pending))
1114 goto out_unfreeze;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001115
1116 set_bit(DMF_SUSPENDED, &md->flags);
1117
1118 map = dm_get_table(md);
1119 if (map)
1120 dm_table_postsuspend_targets(map);
1121 dm_table_put(map);
1122 up_write(&md->lock);
1123
1124 return 0;
Alasdair G Kergonb84b0282005-05-05 16:16:06 -07001125
1126out_unfreeze:
Alasdair G Kergonb84b0282005-05-05 16:16:06 -07001127 __unlock_fs(md);
1128 clear_bit(DMF_BLOCK_IO, &md->flags);
1129out_write_unlock:
1130 up_write(&md->lock);
1131 return error;
1132
1133out_read_unlock:
1134 up_read(&md->lock);
1135 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001136}
1137
1138int dm_resume(struct mapped_device *md)
1139{
1140 struct bio *def;
1141 struct dm_table *map = dm_get_table(md);
1142
1143 down_write(&md->lock);
1144 if (!map ||
1145 !test_bit(DMF_SUSPENDED, &md->flags) ||
1146 !dm_table_get_size(map)) {
1147 up_write(&md->lock);
1148 dm_table_put(map);
1149 return -EINVAL;
1150 }
1151
1152 dm_table_resume_targets(map);
1153 clear_bit(DMF_SUSPENDED, &md->flags);
1154 clear_bit(DMF_BLOCK_IO, &md->flags);
1155
1156 def = bio_list_get(&md->deferred);
1157 __flush_deferred_io(md, def);
1158 up_write(&md->lock);
1159 __unlock_fs(md);
1160 dm_table_unplug_all(map);
1161 dm_table_put(map);
1162
1163 return 0;
1164}
1165
1166/*-----------------------------------------------------------------
1167 * Event notification.
1168 *---------------------------------------------------------------*/
1169uint32_t dm_get_event_nr(struct mapped_device *md)
1170{
1171 return atomic_read(&md->event_nr);
1172}
1173
1174int dm_wait_event(struct mapped_device *md, int event_nr)
1175{
1176 return wait_event_interruptible(md->eventq,
1177 (event_nr != atomic_read(&md->event_nr)));
1178}
1179
1180/*
1181 * The gendisk is only valid as long as you have a reference
1182 * count on 'md'.
1183 */
1184struct gendisk *dm_disk(struct mapped_device *md)
1185{
1186 return md->disk;
1187}
1188
1189int dm_suspended(struct mapped_device *md)
1190{
1191 return test_bit(DMF_SUSPENDED, &md->flags);
1192}
1193
1194static struct block_device_operations dm_blk_dops = {
1195 .open = dm_blk_open,
1196 .release = dm_blk_close,
1197 .owner = THIS_MODULE
1198};
1199
1200EXPORT_SYMBOL(dm_get_mapinfo);
1201
1202/*
1203 * module hooks
1204 */
1205module_init(dm_init);
1206module_exit(dm_exit);
1207
1208module_param(major, uint, 0);
1209MODULE_PARM_DESC(major, "The major number of the device mapper");
1210MODULE_DESCRIPTION(DM_NAME " driver");
1211MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
1212MODULE_LICENSE("GPL");