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1da177e4 LT |
1 | /* |
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 | ||
21 | static const char *_name = DM_NAME; | |
22 | ||
23 | static unsigned int major = 0; | |
24 | static unsigned int _major = 0; | |
25 | ||
26 | /* | |
27 | * One of these is allocated per bio. | |
28 | */ | |
29 | struct 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 | */ | |
40 | struct target_io { | |
41 | struct dm_io *io; | |
42 | struct dm_target *ti; | |
43 | union map_info info; | |
44 | }; | |
45 | ||
46 | union 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 | ||
60 | struct 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; | |
100 | }; | |
101 | ||
102 | #define MIN_IOS 256 | |
103 | static kmem_cache_t *_io_cache; | |
104 | static kmem_cache_t *_tio_cache; | |
105 | ||
106 | static struct bio_set *dm_set; | |
107 | ||
108 | static int __init local_init(void) | |
109 | { | |
110 | int r; | |
111 | ||
112 | dm_set = bioset_create(16, 16, 4); | |
113 | if (!dm_set) | |
114 | return -ENOMEM; | |
115 | ||
116 | /* allocate a slab for the dm_ios */ | |
117 | _io_cache = kmem_cache_create("dm_io", | |
118 | sizeof(struct dm_io), 0, 0, NULL, NULL); | |
119 | if (!_io_cache) | |
120 | return -ENOMEM; | |
121 | ||
122 | /* allocate a slab for the target ios */ | |
123 | _tio_cache = kmem_cache_create("dm_tio", sizeof(struct target_io), | |
124 | 0, 0, NULL, NULL); | |
125 | if (!_tio_cache) { | |
126 | kmem_cache_destroy(_io_cache); | |
127 | return -ENOMEM; | |
128 | } | |
129 | ||
130 | _major = major; | |
131 | r = register_blkdev(_major, _name); | |
132 | if (r < 0) { | |
133 | kmem_cache_destroy(_tio_cache); | |
134 | kmem_cache_destroy(_io_cache); | |
135 | return r; | |
136 | } | |
137 | ||
138 | if (!_major) | |
139 | _major = r; | |
140 | ||
141 | return 0; | |
142 | } | |
143 | ||
144 | static void local_exit(void) | |
145 | { | |
146 | kmem_cache_destroy(_tio_cache); | |
147 | kmem_cache_destroy(_io_cache); | |
148 | ||
149 | bioset_free(dm_set); | |
150 | ||
151 | if (unregister_blkdev(_major, _name) < 0) | |
152 | DMERR("devfs_unregister_blkdev failed"); | |
153 | ||
154 | _major = 0; | |
155 | ||
156 | DMINFO("cleaned up"); | |
157 | } | |
158 | ||
159 | int (*_inits[])(void) __initdata = { | |
160 | local_init, | |
161 | dm_target_init, | |
162 | dm_linear_init, | |
163 | dm_stripe_init, | |
164 | dm_interface_init, | |
165 | }; | |
166 | ||
167 | void (*_exits[])(void) = { | |
168 | local_exit, | |
169 | dm_target_exit, | |
170 | dm_linear_exit, | |
171 | dm_stripe_exit, | |
172 | dm_interface_exit, | |
173 | }; | |
174 | ||
175 | static int __init dm_init(void) | |
176 | { | |
177 | const int count = ARRAY_SIZE(_inits); | |
178 | ||
179 | int r, i; | |
180 | ||
181 | for (i = 0; i < count; i++) { | |
182 | r = _inits[i](); | |
183 | if (r) | |
184 | goto bad; | |
185 | } | |
186 | ||
187 | return 0; | |
188 | ||
189 | bad: | |
190 | while (i--) | |
191 | _exits[i](); | |
192 | ||
193 | return r; | |
194 | } | |
195 | ||
196 | static void __exit dm_exit(void) | |
197 | { | |
198 | int i = ARRAY_SIZE(_exits); | |
199 | ||
200 | while (i--) | |
201 | _exits[i](); | |
202 | } | |
203 | ||
204 | /* | |
205 | * Block device functions | |
206 | */ | |
207 | static int dm_blk_open(struct inode *inode, struct file *file) | |
208 | { | |
209 | struct mapped_device *md; | |
210 | ||
211 | md = inode->i_bdev->bd_disk->private_data; | |
212 | dm_get(md); | |
213 | return 0; | |
214 | } | |
215 | ||
216 | static int dm_blk_close(struct inode *inode, struct file *file) | |
217 | { | |
218 | struct mapped_device *md; | |
219 | ||
220 | md = inode->i_bdev->bd_disk->private_data; | |
221 | dm_put(md); | |
222 | return 0; | |
223 | } | |
224 | ||
225 | static inline struct dm_io *alloc_io(struct mapped_device *md) | |
226 | { | |
227 | return mempool_alloc(md->io_pool, GFP_NOIO); | |
228 | } | |
229 | ||
230 | static inline void free_io(struct mapped_device *md, struct dm_io *io) | |
231 | { | |
232 | mempool_free(io, md->io_pool); | |
233 | } | |
234 | ||
235 | static inline struct target_io *alloc_tio(struct mapped_device *md) | |
236 | { | |
237 | return mempool_alloc(md->tio_pool, GFP_NOIO); | |
238 | } | |
239 | ||
240 | static inline void free_tio(struct mapped_device *md, struct target_io *tio) | |
241 | { | |
242 | mempool_free(tio, md->tio_pool); | |
243 | } | |
244 | ||
245 | /* | |
246 | * Add the bio to the list of deferred io. | |
247 | */ | |
248 | static int queue_io(struct mapped_device *md, struct bio *bio) | |
249 | { | |
250 | down_write(&md->lock); | |
251 | ||
252 | if (!test_bit(DMF_BLOCK_IO, &md->flags)) { | |
253 | up_write(&md->lock); | |
254 | return 1; | |
255 | } | |
256 | ||
257 | bio_list_add(&md->deferred, bio); | |
258 | ||
259 | up_write(&md->lock); | |
260 | return 0; /* deferred successfully */ | |
261 | } | |
262 | ||
263 | /* | |
264 | * Everyone (including functions in this file), should use this | |
265 | * function to access the md->map field, and make sure they call | |
266 | * dm_table_put() when finished. | |
267 | */ | |
268 | struct dm_table *dm_get_table(struct mapped_device *md) | |
269 | { | |
270 | struct dm_table *t; | |
271 | ||
272 | read_lock(&md->map_lock); | |
273 | t = md->map; | |
274 | if (t) | |
275 | dm_table_get(t); | |
276 | read_unlock(&md->map_lock); | |
277 | ||
278 | return t; | |
279 | } | |
280 | ||
281 | /*----------------------------------------------------------------- | |
282 | * CRUD START: | |
283 | * A more elegant soln is in the works that uses the queue | |
284 | * merge fn, unfortunately there are a couple of changes to | |
285 | * the block layer that I want to make for this. So in the | |
286 | * interests of getting something for people to use I give | |
287 | * you this clearly demarcated crap. | |
288 | *---------------------------------------------------------------*/ | |
289 | ||
290 | /* | |
291 | * Decrements the number of outstanding ios that a bio has been | |
292 | * cloned into, completing the original io if necc. | |
293 | */ | |
294 | static inline void dec_pending(struct dm_io *io, int error) | |
295 | { | |
296 | if (error) | |
297 | io->error = error; | |
298 | ||
299 | if (atomic_dec_and_test(&io->io_count)) { | |
300 | if (atomic_dec_and_test(&io->md->pending)) | |
301 | /* nudge anyone waiting on suspend queue */ | |
302 | wake_up(&io->md->wait); | |
303 | ||
304 | bio_endio(io->bio, io->bio->bi_size, io->error); | |
305 | free_io(io->md, io); | |
306 | } | |
307 | } | |
308 | ||
309 | static int clone_endio(struct bio *bio, unsigned int done, int error) | |
310 | { | |
311 | int r = 0; | |
312 | struct target_io *tio = bio->bi_private; | |
313 | struct dm_io *io = tio->io; | |
314 | dm_endio_fn endio = tio->ti->type->end_io; | |
315 | ||
316 | if (bio->bi_size) | |
317 | return 1; | |
318 | ||
319 | if (!bio_flagged(bio, BIO_UPTODATE) && !error) | |
320 | error = -EIO; | |
321 | ||
322 | if (endio) { | |
323 | r = endio(tio->ti, bio, error, &tio->info); | |
324 | if (r < 0) | |
325 | error = r; | |
326 | ||
327 | else if (r > 0) | |
328 | /* the target wants another shot at the io */ | |
329 | return 1; | |
330 | } | |
331 | ||
332 | free_tio(io->md, tio); | |
333 | dec_pending(io, error); | |
334 | bio_put(bio); | |
335 | return r; | |
336 | } | |
337 | ||
338 | static sector_t max_io_len(struct mapped_device *md, | |
339 | sector_t sector, struct dm_target *ti) | |
340 | { | |
341 | sector_t offset = sector - ti->begin; | |
342 | sector_t len = ti->len - offset; | |
343 | ||
344 | /* | |
345 | * Does the target need to split even further ? | |
346 | */ | |
347 | if (ti->split_io) { | |
348 | sector_t boundary; | |
349 | boundary = ((offset + ti->split_io) & ~(ti->split_io - 1)) | |
350 | - offset; | |
351 | if (len > boundary) | |
352 | len = boundary; | |
353 | } | |
354 | ||
355 | return len; | |
356 | } | |
357 | ||
358 | static void __map_bio(struct dm_target *ti, struct bio *clone, | |
359 | struct target_io *tio) | |
360 | { | |
361 | int r; | |
362 | ||
363 | /* | |
364 | * Sanity checks. | |
365 | */ | |
366 | BUG_ON(!clone->bi_size); | |
367 | ||
368 | clone->bi_end_io = clone_endio; | |
369 | clone->bi_private = tio; | |
370 | ||
371 | /* | |
372 | * Map the clone. If r == 0 we don't need to do | |
373 | * anything, the target has assumed ownership of | |
374 | * this io. | |
375 | */ | |
376 | atomic_inc(&tio->io->io_count); | |
377 | r = ti->type->map(ti, clone, &tio->info); | |
378 | if (r > 0) | |
379 | /* the bio has been remapped so dispatch it */ | |
380 | generic_make_request(clone); | |
381 | ||
382 | else if (r < 0) { | |
383 | /* error the io and bail out */ | |
384 | struct dm_io *io = tio->io; | |
385 | free_tio(tio->io->md, tio); | |
386 | dec_pending(io, -EIO); | |
387 | bio_put(clone); | |
388 | } | |
389 | } | |
390 | ||
391 | struct clone_info { | |
392 | struct mapped_device *md; | |
393 | struct dm_table *map; | |
394 | struct bio *bio; | |
395 | struct dm_io *io; | |
396 | sector_t sector; | |
397 | sector_t sector_count; | |
398 | unsigned short idx; | |
399 | }; | |
400 | ||
401 | /* | |
402 | * Creates a little bio that is just does part of a bvec. | |
403 | */ | |
404 | static struct bio *split_bvec(struct bio *bio, sector_t sector, | |
405 | unsigned short idx, unsigned int offset, | |
406 | unsigned int len) | |
407 | { | |
408 | struct bio *clone; | |
409 | struct bio_vec *bv = bio->bi_io_vec + idx; | |
410 | ||
411 | clone = bio_alloc_bioset(GFP_NOIO, 1, dm_set); | |
412 | *clone->bi_io_vec = *bv; | |
413 | ||
414 | clone->bi_sector = sector; | |
415 | clone->bi_bdev = bio->bi_bdev; | |
416 | clone->bi_rw = bio->bi_rw; | |
417 | clone->bi_vcnt = 1; | |
418 | clone->bi_size = to_bytes(len); | |
419 | clone->bi_io_vec->bv_offset = offset; | |
420 | clone->bi_io_vec->bv_len = clone->bi_size; | |
421 | ||
422 | return clone; | |
423 | } | |
424 | ||
425 | /* | |
426 | * Creates a bio that consists of range of complete bvecs. | |
427 | */ | |
428 | static struct bio *clone_bio(struct bio *bio, sector_t sector, | |
429 | unsigned short idx, unsigned short bv_count, | |
430 | unsigned int len) | |
431 | { | |
432 | struct bio *clone; | |
433 | ||
434 | clone = bio_clone(bio, GFP_NOIO); | |
435 | clone->bi_sector = sector; | |
436 | clone->bi_idx = idx; | |
437 | clone->bi_vcnt = idx + bv_count; | |
438 | clone->bi_size = to_bytes(len); | |
439 | clone->bi_flags &= ~(1 << BIO_SEG_VALID); | |
440 | ||
441 | return clone; | |
442 | } | |
443 | ||
444 | static void __clone_and_map(struct clone_info *ci) | |
445 | { | |
446 | struct bio *clone, *bio = ci->bio; | |
447 | struct dm_target *ti = dm_table_find_target(ci->map, ci->sector); | |
448 | sector_t len = 0, max = max_io_len(ci->md, ci->sector, ti); | |
449 | struct target_io *tio; | |
450 | ||
451 | /* | |
452 | * Allocate a target io object. | |
453 | */ | |
454 | tio = alloc_tio(ci->md); | |
455 | tio->io = ci->io; | |
456 | tio->ti = ti; | |
457 | memset(&tio->info, 0, sizeof(tio->info)); | |
458 | ||
459 | if (ci->sector_count <= max) { | |
460 | /* | |
461 | * Optimise for the simple case where we can do all of | |
462 | * the remaining io with a single clone. | |
463 | */ | |
464 | clone = clone_bio(bio, ci->sector, ci->idx, | |
465 | bio->bi_vcnt - ci->idx, ci->sector_count); | |
466 | __map_bio(ti, clone, tio); | |
467 | ci->sector_count = 0; | |
468 | ||
469 | } else if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) { | |
470 | /* | |
471 | * There are some bvecs that don't span targets. | |
472 | * Do as many of these as possible. | |
473 | */ | |
474 | int i; | |
475 | sector_t remaining = max; | |
476 | sector_t bv_len; | |
477 | ||
478 | for (i = ci->idx; remaining && (i < bio->bi_vcnt); i++) { | |
479 | bv_len = to_sector(bio->bi_io_vec[i].bv_len); | |
480 | ||
481 | if (bv_len > remaining) | |
482 | break; | |
483 | ||
484 | remaining -= bv_len; | |
485 | len += bv_len; | |
486 | } | |
487 | ||
488 | clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len); | |
489 | __map_bio(ti, clone, tio); | |
490 | ||
491 | ci->sector += len; | |
492 | ci->sector_count -= len; | |
493 | ci->idx = i; | |
494 | ||
495 | } else { | |
496 | /* | |
497 | * Create two copy bios to deal with io that has | |
498 | * been split across a target. | |
499 | */ | |
500 | struct bio_vec *bv = bio->bi_io_vec + ci->idx; | |
501 | ||
502 | clone = split_bvec(bio, ci->sector, ci->idx, | |
503 | bv->bv_offset, max); | |
504 | __map_bio(ti, clone, tio); | |
505 | ||
506 | ci->sector += max; | |
507 | ci->sector_count -= max; | |
508 | ti = dm_table_find_target(ci->map, ci->sector); | |
509 | ||
510 | len = to_sector(bv->bv_len) - max; | |
511 | clone = split_bvec(bio, ci->sector, ci->idx, | |
512 | bv->bv_offset + to_bytes(max), len); | |
513 | tio = alloc_tio(ci->md); | |
514 | tio->io = ci->io; | |
515 | tio->ti = ti; | |
516 | memset(&tio->info, 0, sizeof(tio->info)); | |
517 | __map_bio(ti, clone, tio); | |
518 | ||
519 | ci->sector += len; | |
520 | ci->sector_count -= len; | |
521 | ci->idx++; | |
522 | } | |
523 | } | |
524 | ||
525 | /* | |
526 | * Split the bio into several clones. | |
527 | */ | |
528 | static void __split_bio(struct mapped_device *md, struct bio *bio) | |
529 | { | |
530 | struct clone_info ci; | |
531 | ||
532 | ci.map = dm_get_table(md); | |
533 | if (!ci.map) { | |
534 | bio_io_error(bio, bio->bi_size); | |
535 | return; | |
536 | } | |
537 | ||
538 | ci.md = md; | |
539 | ci.bio = bio; | |
540 | ci.io = alloc_io(md); | |
541 | ci.io->error = 0; | |
542 | atomic_set(&ci.io->io_count, 1); | |
543 | ci.io->bio = bio; | |
544 | ci.io->md = md; | |
545 | ci.sector = bio->bi_sector; | |
546 | ci.sector_count = bio_sectors(bio); | |
547 | ci.idx = bio->bi_idx; | |
548 | ||
549 | atomic_inc(&md->pending); | |
550 | while (ci.sector_count) | |
551 | __clone_and_map(&ci); | |
552 | ||
553 | /* drop the extra reference count */ | |
554 | dec_pending(ci.io, 0); | |
555 | dm_table_put(ci.map); | |
556 | } | |
557 | /*----------------------------------------------------------------- | |
558 | * CRUD END | |
559 | *---------------------------------------------------------------*/ | |
560 | ||
561 | /* | |
562 | * The request function that just remaps the bio built up by | |
563 | * dm_merge_bvec. | |
564 | */ | |
565 | static int dm_request(request_queue_t *q, struct bio *bio) | |
566 | { | |
567 | int r; | |
568 | struct mapped_device *md = q->queuedata; | |
569 | ||
570 | down_read(&md->lock); | |
571 | ||
572 | /* | |
573 | * If we're suspended we have to queue | |
574 | * this io for later. | |
575 | */ | |
576 | while (test_bit(DMF_BLOCK_IO, &md->flags)) { | |
577 | up_read(&md->lock); | |
578 | ||
579 | if (bio_rw(bio) == READA) { | |
580 | bio_io_error(bio, bio->bi_size); | |
581 | return 0; | |
582 | } | |
583 | ||
584 | r = queue_io(md, bio); | |
585 | if (r < 0) { | |
586 | bio_io_error(bio, bio->bi_size); | |
587 | return 0; | |
588 | ||
589 | } else if (r == 0) | |
590 | return 0; /* deferred successfully */ | |
591 | ||
592 | /* | |
593 | * We're in a while loop, because someone could suspend | |
594 | * before we get to the following read lock. | |
595 | */ | |
596 | down_read(&md->lock); | |
597 | } | |
598 | ||
599 | __split_bio(md, bio); | |
600 | up_read(&md->lock); | |
601 | return 0; | |
602 | } | |
603 | ||
604 | static int dm_flush_all(request_queue_t *q, struct gendisk *disk, | |
605 | sector_t *error_sector) | |
606 | { | |
607 | struct mapped_device *md = q->queuedata; | |
608 | struct dm_table *map = dm_get_table(md); | |
609 | int ret = -ENXIO; | |
610 | ||
611 | if (map) { | |
612 | ret = dm_table_flush_all(md->map); | |
613 | dm_table_put(map); | |
614 | } | |
615 | ||
616 | return ret; | |
617 | } | |
618 | ||
619 | static void dm_unplug_all(request_queue_t *q) | |
620 | { | |
621 | struct mapped_device *md = q->queuedata; | |
622 | struct dm_table *map = dm_get_table(md); | |
623 | ||
624 | if (map) { | |
625 | dm_table_unplug_all(map); | |
626 | dm_table_put(map); | |
627 | } | |
628 | } | |
629 | ||
630 | static int dm_any_congested(void *congested_data, int bdi_bits) | |
631 | { | |
632 | int r; | |
633 | struct mapped_device *md = (struct mapped_device *) congested_data; | |
634 | struct dm_table *map = dm_get_table(md); | |
635 | ||
636 | if (!map || test_bit(DMF_BLOCK_IO, &md->flags)) | |
637 | r = bdi_bits; | |
638 | else | |
639 | r = dm_table_any_congested(map, bdi_bits); | |
640 | ||
641 | dm_table_put(map); | |
642 | return r; | |
643 | } | |
644 | ||
645 | /*----------------------------------------------------------------- | |
646 | * An IDR is used to keep track of allocated minor numbers. | |
647 | *---------------------------------------------------------------*/ | |
648 | static DECLARE_MUTEX(_minor_lock); | |
649 | static DEFINE_IDR(_minor_idr); | |
650 | ||
651 | static void free_minor(unsigned int minor) | |
652 | { | |
653 | down(&_minor_lock); | |
654 | idr_remove(&_minor_idr, minor); | |
655 | up(&_minor_lock); | |
656 | } | |
657 | ||
658 | /* | |
659 | * See if the device with a specific minor # is free. | |
660 | */ | |
661 | static int specific_minor(struct mapped_device *md, unsigned int minor) | |
662 | { | |
663 | int r, m; | |
664 | ||
665 | if (minor >= (1 << MINORBITS)) | |
666 | return -EINVAL; | |
667 | ||
668 | down(&_minor_lock); | |
669 | ||
670 | if (idr_find(&_minor_idr, minor)) { | |
671 | r = -EBUSY; | |
672 | goto out; | |
673 | } | |
674 | ||
675 | r = idr_pre_get(&_minor_idr, GFP_KERNEL); | |
676 | if (!r) { | |
677 | r = -ENOMEM; | |
678 | goto out; | |
679 | } | |
680 | ||
681 | r = idr_get_new_above(&_minor_idr, md, minor, &m); | |
682 | if (r) { | |
683 | goto out; | |
684 | } | |
685 | ||
686 | if (m != minor) { | |
687 | idr_remove(&_minor_idr, m); | |
688 | r = -EBUSY; | |
689 | goto out; | |
690 | } | |
691 | ||
692 | out: | |
693 | up(&_minor_lock); | |
694 | return r; | |
695 | } | |
696 | ||
697 | static int next_free_minor(struct mapped_device *md, unsigned int *minor) | |
698 | { | |
699 | int r; | |
700 | unsigned int m; | |
701 | ||
702 | down(&_minor_lock); | |
703 | ||
704 | r = idr_pre_get(&_minor_idr, GFP_KERNEL); | |
705 | if (!r) { | |
706 | r = -ENOMEM; | |
707 | goto out; | |
708 | } | |
709 | ||
710 | r = idr_get_new(&_minor_idr, md, &m); | |
711 | if (r) { | |
712 | goto out; | |
713 | } | |
714 | ||
715 | if (m >= (1 << MINORBITS)) { | |
716 | idr_remove(&_minor_idr, m); | |
717 | r = -ENOSPC; | |
718 | goto out; | |
719 | } | |
720 | ||
721 | *minor = m; | |
722 | ||
723 | out: | |
724 | up(&_minor_lock); | |
725 | return r; | |
726 | } | |
727 | ||
728 | static struct block_device_operations dm_blk_dops; | |
729 | ||
730 | /* | |
731 | * Allocate and initialise a blank device with a given minor. | |
732 | */ | |
733 | static struct mapped_device *alloc_dev(unsigned int minor, int persistent) | |
734 | { | |
735 | int r; | |
736 | struct mapped_device *md = kmalloc(sizeof(*md), GFP_KERNEL); | |
737 | ||
738 | if (!md) { | |
739 | DMWARN("unable to allocate device, out of memory."); | |
740 | return NULL; | |
741 | } | |
742 | ||
743 | /* get a minor number for the dev */ | |
744 | r = persistent ? specific_minor(md, minor) : next_free_minor(md, &minor); | |
745 | if (r < 0) | |
746 | goto bad1; | |
747 | ||
748 | memset(md, 0, sizeof(*md)); | |
749 | init_rwsem(&md->lock); | |
750 | rwlock_init(&md->map_lock); | |
751 | atomic_set(&md->holders, 1); | |
752 | atomic_set(&md->event_nr, 0); | |
753 | ||
754 | md->queue = blk_alloc_queue(GFP_KERNEL); | |
755 | if (!md->queue) | |
756 | goto bad1; | |
757 | ||
758 | md->queue->queuedata = md; | |
759 | md->queue->backing_dev_info.congested_fn = dm_any_congested; | |
760 | md->queue->backing_dev_info.congested_data = md; | |
761 | blk_queue_make_request(md->queue, dm_request); | |
762 | md->queue->unplug_fn = dm_unplug_all; | |
763 | md->queue->issue_flush_fn = dm_flush_all; | |
764 | ||
765 | md->io_pool = mempool_create(MIN_IOS, mempool_alloc_slab, | |
766 | mempool_free_slab, _io_cache); | |
767 | if (!md->io_pool) | |
768 | goto bad2; | |
769 | ||
770 | md->tio_pool = mempool_create(MIN_IOS, mempool_alloc_slab, | |
771 | mempool_free_slab, _tio_cache); | |
772 | if (!md->tio_pool) | |
773 | goto bad3; | |
774 | ||
775 | md->disk = alloc_disk(1); | |
776 | if (!md->disk) | |
777 | goto bad4; | |
778 | ||
779 | md->disk->major = _major; | |
780 | md->disk->first_minor = minor; | |
781 | md->disk->fops = &dm_blk_dops; | |
782 | md->disk->queue = md->queue; | |
783 | md->disk->private_data = md; | |
784 | sprintf(md->disk->disk_name, "dm-%d", minor); | |
785 | add_disk(md->disk); | |
786 | ||
787 | atomic_set(&md->pending, 0); | |
788 | init_waitqueue_head(&md->wait); | |
789 | init_waitqueue_head(&md->eventq); | |
790 | ||
791 | return md; | |
792 | ||
793 | bad4: | |
794 | mempool_destroy(md->tio_pool); | |
795 | bad3: | |
796 | mempool_destroy(md->io_pool); | |
797 | bad2: | |
798 | blk_put_queue(md->queue); | |
799 | free_minor(minor); | |
800 | bad1: | |
801 | kfree(md); | |
802 | return NULL; | |
803 | } | |
804 | ||
805 | static void free_dev(struct mapped_device *md) | |
806 | { | |
807 | free_minor(md->disk->first_minor); | |
808 | mempool_destroy(md->tio_pool); | |
809 | mempool_destroy(md->io_pool); | |
810 | del_gendisk(md->disk); | |
811 | put_disk(md->disk); | |
812 | blk_put_queue(md->queue); | |
813 | kfree(md); | |
814 | } | |
815 | ||
816 | /* | |
817 | * Bind a table to the device. | |
818 | */ | |
819 | static void event_callback(void *context) | |
820 | { | |
821 | struct mapped_device *md = (struct mapped_device *) context; | |
822 | ||
823 | atomic_inc(&md->event_nr); | |
824 | wake_up(&md->eventq); | |
825 | } | |
826 | ||
827 | static void __set_size(struct gendisk *disk, sector_t size) | |
828 | { | |
829 | struct block_device *bdev; | |
830 | ||
831 | set_capacity(disk, size); | |
832 | bdev = bdget_disk(disk, 0); | |
833 | if (bdev) { | |
834 | down(&bdev->bd_inode->i_sem); | |
835 | i_size_write(bdev->bd_inode, (loff_t)size << SECTOR_SHIFT); | |
836 | up(&bdev->bd_inode->i_sem); | |
837 | bdput(bdev); | |
838 | } | |
839 | } | |
840 | ||
841 | static int __bind(struct mapped_device *md, struct dm_table *t) | |
842 | { | |
843 | request_queue_t *q = md->queue; | |
844 | sector_t size; | |
845 | ||
846 | size = dm_table_get_size(t); | |
847 | __set_size(md->disk, size); | |
848 | if (size == 0) | |
849 | return 0; | |
850 | ||
851 | write_lock(&md->map_lock); | |
852 | md->map = t; | |
853 | write_unlock(&md->map_lock); | |
854 | ||
855 | dm_table_get(t); | |
856 | dm_table_event_callback(md->map, event_callback, md); | |
857 | dm_table_set_restrictions(t, q); | |
858 | return 0; | |
859 | } | |
860 | ||
861 | static void __unbind(struct mapped_device *md) | |
862 | { | |
863 | struct dm_table *map = md->map; | |
864 | ||
865 | if (!map) | |
866 | return; | |
867 | ||
868 | dm_table_event_callback(map, NULL, NULL); | |
869 | write_lock(&md->map_lock); | |
870 | md->map = NULL; | |
871 | write_unlock(&md->map_lock); | |
872 | dm_table_put(map); | |
873 | } | |
874 | ||
875 | /* | |
876 | * Constructor for a new device. | |
877 | */ | |
878 | static int create_aux(unsigned int minor, int persistent, | |
879 | struct mapped_device **result) | |
880 | { | |
881 | struct mapped_device *md; | |
882 | ||
883 | md = alloc_dev(minor, persistent); | |
884 | if (!md) | |
885 | return -ENXIO; | |
886 | ||
887 | *result = md; | |
888 | return 0; | |
889 | } | |
890 | ||
891 | int dm_create(struct mapped_device **result) | |
892 | { | |
893 | return create_aux(0, 0, result); | |
894 | } | |
895 | ||
896 | int dm_create_with_minor(unsigned int minor, struct mapped_device **result) | |
897 | { | |
898 | return create_aux(minor, 1, result); | |
899 | } | |
900 | ||
901 | void *dm_get_mdptr(dev_t dev) | |
902 | { | |
903 | struct mapped_device *md; | |
904 | void *mdptr = NULL; | |
905 | unsigned minor = MINOR(dev); | |
906 | ||
907 | if (MAJOR(dev) != _major || minor >= (1 << MINORBITS)) | |
908 | return NULL; | |
909 | ||
910 | down(&_minor_lock); | |
911 | ||
912 | md = idr_find(&_minor_idr, minor); | |
913 | ||
914 | if (md && (dm_disk(md)->first_minor == minor)) | |
915 | mdptr = md->interface_ptr; | |
916 | ||
917 | up(&_minor_lock); | |
918 | ||
919 | return mdptr; | |
920 | } | |
921 | ||
922 | void dm_set_mdptr(struct mapped_device *md, void *ptr) | |
923 | { | |
924 | md->interface_ptr = ptr; | |
925 | } | |
926 | ||
927 | void dm_get(struct mapped_device *md) | |
928 | { | |
929 | atomic_inc(&md->holders); | |
930 | } | |
931 | ||
932 | void dm_put(struct mapped_device *md) | |
933 | { | |
934 | struct dm_table *map = dm_get_table(md); | |
935 | ||
936 | if (atomic_dec_and_test(&md->holders)) { | |
937 | if (!test_bit(DMF_SUSPENDED, &md->flags) && map) { | |
938 | dm_table_presuspend_targets(map); | |
939 | dm_table_postsuspend_targets(map); | |
940 | } | |
941 | __unbind(md); | |
942 | free_dev(md); | |
943 | } | |
944 | ||
945 | dm_table_put(map); | |
946 | } | |
947 | ||
948 | /* | |
949 | * Process the deferred bios | |
950 | */ | |
951 | static void __flush_deferred_io(struct mapped_device *md, struct bio *c) | |
952 | { | |
953 | struct bio *n; | |
954 | ||
955 | while (c) { | |
956 | n = c->bi_next; | |
957 | c->bi_next = NULL; | |
958 | __split_bio(md, c); | |
959 | c = n; | |
960 | } | |
961 | } | |
962 | ||
963 | /* | |
964 | * Swap in a new table (destroying old one). | |
965 | */ | |
966 | int dm_swap_table(struct mapped_device *md, struct dm_table *table) | |
967 | { | |
968 | int r; | |
969 | ||
970 | down_write(&md->lock); | |
971 | ||
972 | /* device must be suspended */ | |
973 | if (!test_bit(DMF_SUSPENDED, &md->flags)) { | |
974 | up_write(&md->lock); | |
975 | return -EPERM; | |
976 | } | |
977 | ||
978 | __unbind(md); | |
979 | r = __bind(md, table); | |
980 | if (r) | |
981 | return r; | |
982 | ||
983 | up_write(&md->lock); | |
984 | return 0; | |
985 | } | |
986 | ||
987 | /* | |
988 | * Functions to lock and unlock any filesystem running on the | |
989 | * device. | |
990 | */ | |
991 | static int __lock_fs(struct mapped_device *md) | |
992 | { | |
993 | struct block_device *bdev; | |
994 | ||
995 | if (test_and_set_bit(DMF_FS_LOCKED, &md->flags)) | |
996 | return 0; | |
997 | ||
998 | bdev = bdget_disk(md->disk, 0); | |
999 | if (!bdev) { | |
1000 | DMWARN("bdget failed in __lock_fs"); | |
1001 | return -ENOMEM; | |
1002 | } | |
1003 | ||
1004 | WARN_ON(md->frozen_sb); | |
1005 | md->frozen_sb = freeze_bdev(bdev); | |
1006 | /* don't bdput right now, we don't want the bdev | |
1007 | * to go away while it is locked. We'll bdput | |
1008 | * in __unlock_fs | |
1009 | */ | |
1010 | return 0; | |
1011 | } | |
1012 | ||
1013 | static int __unlock_fs(struct mapped_device *md) | |
1014 | { | |
1015 | struct block_device *bdev; | |
1016 | ||
1017 | if (!test_and_clear_bit(DMF_FS_LOCKED, &md->flags)) | |
1018 | return 0; | |
1019 | ||
1020 | bdev = bdget_disk(md->disk, 0); | |
1021 | if (!bdev) { | |
1022 | DMWARN("bdget failed in __unlock_fs"); | |
1023 | return -ENOMEM; | |
1024 | } | |
1025 | ||
1026 | thaw_bdev(bdev, md->frozen_sb); | |
1027 | md->frozen_sb = NULL; | |
1028 | bdput(bdev); | |
1029 | bdput(bdev); | |
1030 | return 0; | |
1031 | } | |
1032 | ||
1033 | /* | |
1034 | * We need to be able to change a mapping table under a mounted | |
1035 | * filesystem. For example we might want to move some data in | |
1036 | * the background. Before the table can be swapped with | |
1037 | * dm_bind_table, dm_suspend must be called to flush any in | |
1038 | * flight bios and ensure that any further io gets deferred. | |
1039 | */ | |
1040 | int dm_suspend(struct mapped_device *md) | |
1041 | { | |
1042 | struct dm_table *map; | |
1043 | DECLARE_WAITQUEUE(wait, current); | |
1044 | ||
1045 | /* Flush I/O to the device. */ | |
1046 | down_read(&md->lock); | |
1047 | if (test_bit(DMF_BLOCK_IO, &md->flags)) { | |
1048 | up_read(&md->lock); | |
1049 | return -EINVAL; | |
1050 | } | |
1051 | ||
1052 | map = dm_get_table(md); | |
1053 | if (map) | |
1054 | dm_table_presuspend_targets(map); | |
1055 | __lock_fs(md); | |
1056 | ||
1057 | up_read(&md->lock); | |
1058 | ||
1059 | /* | |
1060 | * First we set the BLOCK_IO flag so no more ios will be | |
1061 | * mapped. | |
1062 | */ | |
1063 | down_write(&md->lock); | |
1064 | if (test_bit(DMF_BLOCK_IO, &md->flags)) { | |
1065 | /* | |
1066 | * If we get here we know another thread is | |
1067 | * trying to suspend as well, so we leave the fs | |
1068 | * locked for this thread. | |
1069 | */ | |
1070 | up_write(&md->lock); | |
1071 | return -EINVAL; | |
1072 | } | |
1073 | ||
1074 | set_bit(DMF_BLOCK_IO, &md->flags); | |
1075 | add_wait_queue(&md->wait, &wait); | |
1076 | up_write(&md->lock); | |
1077 | ||
1078 | /* unplug */ | |
1079 | if (map) { | |
1080 | dm_table_unplug_all(map); | |
1081 | dm_table_put(map); | |
1082 | } | |
1083 | ||
1084 | /* | |
1085 | * Then we wait for the already mapped ios to | |
1086 | * complete. | |
1087 | */ | |
1088 | while (1) { | |
1089 | set_current_state(TASK_INTERRUPTIBLE); | |
1090 | ||
1091 | if (!atomic_read(&md->pending) || signal_pending(current)) | |
1092 | break; | |
1093 | ||
1094 | io_schedule(); | |
1095 | } | |
1096 | set_current_state(TASK_RUNNING); | |
1097 | ||
1098 | down_write(&md->lock); | |
1099 | remove_wait_queue(&md->wait, &wait); | |
1100 | ||
1101 | /* were we interrupted ? */ | |
1102 | if (atomic_read(&md->pending)) { | |
1103 | __unlock_fs(md); | |
1104 | clear_bit(DMF_BLOCK_IO, &md->flags); | |
1105 | up_write(&md->lock); | |
1106 | return -EINTR; | |
1107 | } | |
1108 | ||
1109 | set_bit(DMF_SUSPENDED, &md->flags); | |
1110 | ||
1111 | map = dm_get_table(md); | |
1112 | if (map) | |
1113 | dm_table_postsuspend_targets(map); | |
1114 | dm_table_put(map); | |
1115 | up_write(&md->lock); | |
1116 | ||
1117 | return 0; | |
1118 | } | |
1119 | ||
1120 | int dm_resume(struct mapped_device *md) | |
1121 | { | |
1122 | struct bio *def; | |
1123 | struct dm_table *map = dm_get_table(md); | |
1124 | ||
1125 | down_write(&md->lock); | |
1126 | if (!map || | |
1127 | !test_bit(DMF_SUSPENDED, &md->flags) || | |
1128 | !dm_table_get_size(map)) { | |
1129 | up_write(&md->lock); | |
1130 | dm_table_put(map); | |
1131 | return -EINVAL; | |
1132 | } | |
1133 | ||
1134 | dm_table_resume_targets(map); | |
1135 | clear_bit(DMF_SUSPENDED, &md->flags); | |
1136 | clear_bit(DMF_BLOCK_IO, &md->flags); | |
1137 | ||
1138 | def = bio_list_get(&md->deferred); | |
1139 | __flush_deferred_io(md, def); | |
1140 | up_write(&md->lock); | |
1141 | __unlock_fs(md); | |
1142 | dm_table_unplug_all(map); | |
1143 | dm_table_put(map); | |
1144 | ||
1145 | return 0; | |
1146 | } | |
1147 | ||
1148 | /*----------------------------------------------------------------- | |
1149 | * Event notification. | |
1150 | *---------------------------------------------------------------*/ | |
1151 | uint32_t dm_get_event_nr(struct mapped_device *md) | |
1152 | { | |
1153 | return atomic_read(&md->event_nr); | |
1154 | } | |
1155 | ||
1156 | int dm_wait_event(struct mapped_device *md, int event_nr) | |
1157 | { | |
1158 | return wait_event_interruptible(md->eventq, | |
1159 | (event_nr != atomic_read(&md->event_nr))); | |
1160 | } | |
1161 | ||
1162 | /* | |
1163 | * The gendisk is only valid as long as you have a reference | |
1164 | * count on 'md'. | |
1165 | */ | |
1166 | struct gendisk *dm_disk(struct mapped_device *md) | |
1167 | { | |
1168 | return md->disk; | |
1169 | } | |
1170 | ||
1171 | int dm_suspended(struct mapped_device *md) | |
1172 | { | |
1173 | return test_bit(DMF_SUSPENDED, &md->flags); | |
1174 | } | |
1175 | ||
1176 | static struct block_device_operations dm_blk_dops = { | |
1177 | .open = dm_blk_open, | |
1178 | .release = dm_blk_close, | |
1179 | .owner = THIS_MODULE | |
1180 | }; | |
1181 | ||
1182 | EXPORT_SYMBOL(dm_get_mapinfo); | |
1183 | ||
1184 | /* | |
1185 | * module hooks | |
1186 | */ | |
1187 | module_init(dm_init); | |
1188 | module_exit(dm_exit); | |
1189 | ||
1190 | module_param(major, uint, 0); | |
1191 | MODULE_PARM_DESC(major, "The major number of the device mapper"); | |
1192 | MODULE_DESCRIPTION(DM_NAME " driver"); | |
1193 | MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>"); | |
1194 | MODULE_LICENSE("GPL"); |