xref: /openbmc/linux/drivers/md/dm-thin-metadata.c (revision 6774def6)
1 /*
2  * Copyright (C) 2011-2012 Red Hat, Inc.
3  *
4  * This file is released under the GPL.
5  */
6 
7 #include "dm-thin-metadata.h"
8 #include "persistent-data/dm-btree.h"
9 #include "persistent-data/dm-space-map.h"
10 #include "persistent-data/dm-space-map-disk.h"
11 #include "persistent-data/dm-transaction-manager.h"
12 
13 #include <linux/list.h>
14 #include <linux/device-mapper.h>
15 #include <linux/workqueue.h>
16 
17 /*--------------------------------------------------------------------------
18  * As far as the metadata goes, there is:
19  *
20  * - A superblock in block zero, taking up fewer than 512 bytes for
21  *   atomic writes.
22  *
23  * - A space map managing the metadata blocks.
24  *
25  * - A space map managing the data blocks.
26  *
27  * - A btree mapping our internal thin dev ids onto struct disk_device_details.
28  *
29  * - A hierarchical btree, with 2 levels which effectively maps (thin
30  *   dev id, virtual block) -> block_time.  Block time is a 64-bit
31  *   field holding the time in the low 24 bits, and block in the top 48
32  *   bits.
33  *
34  * BTrees consist solely of btree_nodes, that fill a block.  Some are
35  * internal nodes, as such their values are a __le64 pointing to other
36  * nodes.  Leaf nodes can store data of any reasonable size (ie. much
37  * smaller than the block size).  The nodes consist of the header,
38  * followed by an array of keys, followed by an array of values.  We have
39  * to binary search on the keys so they're all held together to help the
40  * cpu cache.
41  *
42  * Space maps have 2 btrees:
43  *
44  * - One maps a uint64_t onto a struct index_entry.  Which points to a
45  *   bitmap block, and has some details about how many free entries there
46  *   are etc.
47  *
48  * - The bitmap blocks have a header (for the checksum).  Then the rest
49  *   of the block is pairs of bits.  With the meaning being:
50  *
51  *   0 - ref count is 0
52  *   1 - ref count is 1
53  *   2 - ref count is 2
54  *   3 - ref count is higher than 2
55  *
56  * - If the count is higher than 2 then the ref count is entered in a
57  *   second btree that directly maps the block_address to a uint32_t ref
58  *   count.
59  *
60  * The space map metadata variant doesn't have a bitmaps btree.  Instead
61  * it has one single blocks worth of index_entries.  This avoids
62  * recursive issues with the bitmap btree needing to allocate space in
63  * order to insert.  With a small data block size such as 64k the
64  * metadata support data devices that are hundreds of terrabytes.
65  *
66  * The space maps allocate space linearly from front to back.  Space that
67  * is freed in a transaction is never recycled within that transaction.
68  * To try and avoid fragmenting _free_ space the allocator always goes
69  * back and fills in gaps.
70  *
71  * All metadata io is in THIN_METADATA_BLOCK_SIZE sized/aligned chunks
72  * from the block manager.
73  *--------------------------------------------------------------------------*/
74 
75 #define DM_MSG_PREFIX   "thin metadata"
76 
77 #define THIN_SUPERBLOCK_MAGIC 27022010
78 #define THIN_SUPERBLOCK_LOCATION 0
79 #define THIN_VERSION 2
80 #define THIN_METADATA_CACHE_SIZE 64
81 #define SECTOR_TO_BLOCK_SHIFT 3
82 
83 /*
84  *  3 for btree insert +
85  *  2 for btree lookup used within space map
86  */
87 #define THIN_MAX_CONCURRENT_LOCKS 5
88 
89 /* This should be plenty */
90 #define SPACE_MAP_ROOT_SIZE 128
91 
92 /*
93  * Little endian on-disk superblock and device details.
94  */
95 struct thin_disk_superblock {
96 	__le32 csum;	/* Checksum of superblock except for this field. */
97 	__le32 flags;
98 	__le64 blocknr;	/* This block number, dm_block_t. */
99 
100 	__u8 uuid[16];
101 	__le64 magic;
102 	__le32 version;
103 	__le32 time;
104 
105 	__le64 trans_id;
106 
107 	/*
108 	 * Root held by userspace transactions.
109 	 */
110 	__le64 held_root;
111 
112 	__u8 data_space_map_root[SPACE_MAP_ROOT_SIZE];
113 	__u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
114 
115 	/*
116 	 * 2-level btree mapping (dev_id, (dev block, time)) -> data block
117 	 */
118 	__le64 data_mapping_root;
119 
120 	/*
121 	 * Device detail root mapping dev_id -> device_details
122 	 */
123 	__le64 device_details_root;
124 
125 	__le32 data_block_size;		/* In 512-byte sectors. */
126 
127 	__le32 metadata_block_size;	/* In 512-byte sectors. */
128 	__le64 metadata_nr_blocks;
129 
130 	__le32 compat_flags;
131 	__le32 compat_ro_flags;
132 	__le32 incompat_flags;
133 } __packed;
134 
135 struct disk_device_details {
136 	__le64 mapped_blocks;
137 	__le64 transaction_id;		/* When created. */
138 	__le32 creation_time;
139 	__le32 snapshotted_time;
140 } __packed;
141 
142 struct dm_pool_metadata {
143 	struct hlist_node hash;
144 
145 	struct block_device *bdev;
146 	struct dm_block_manager *bm;
147 	struct dm_space_map *metadata_sm;
148 	struct dm_space_map *data_sm;
149 	struct dm_transaction_manager *tm;
150 	struct dm_transaction_manager *nb_tm;
151 
152 	/*
153 	 * Two-level btree.
154 	 * First level holds thin_dev_t.
155 	 * Second level holds mappings.
156 	 */
157 	struct dm_btree_info info;
158 
159 	/*
160 	 * Non-blocking version of the above.
161 	 */
162 	struct dm_btree_info nb_info;
163 
164 	/*
165 	 * Just the top level for deleting whole devices.
166 	 */
167 	struct dm_btree_info tl_info;
168 
169 	/*
170 	 * Just the bottom level for creating new devices.
171 	 */
172 	struct dm_btree_info bl_info;
173 
174 	/*
175 	 * Describes the device details btree.
176 	 */
177 	struct dm_btree_info details_info;
178 
179 	struct rw_semaphore root_lock;
180 	uint32_t time;
181 	dm_block_t root;
182 	dm_block_t details_root;
183 	struct list_head thin_devices;
184 	uint64_t trans_id;
185 	unsigned long flags;
186 	sector_t data_block_size;
187 	bool read_only:1;
188 
189 	/*
190 	 * Set if a transaction has to be aborted but the attempt to roll back
191 	 * to the previous (good) transaction failed.  The only pool metadata
192 	 * operation possible in this state is the closing of the device.
193 	 */
194 	bool fail_io:1;
195 
196 	/*
197 	 * Reading the space map roots can fail, so we read it into these
198 	 * buffers before the superblock is locked and updated.
199 	 */
200 	__u8 data_space_map_root[SPACE_MAP_ROOT_SIZE];
201 	__u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
202 };
203 
204 struct dm_thin_device {
205 	struct list_head list;
206 	struct dm_pool_metadata *pmd;
207 	dm_thin_id id;
208 
209 	int open_count;
210 	bool changed:1;
211 	bool aborted_with_changes:1;
212 	uint64_t mapped_blocks;
213 	uint64_t transaction_id;
214 	uint32_t creation_time;
215 	uint32_t snapshotted_time;
216 };
217 
218 /*----------------------------------------------------------------
219  * superblock validator
220  *--------------------------------------------------------------*/
221 
222 #define SUPERBLOCK_CSUM_XOR 160774
223 
224 static void sb_prepare_for_write(struct dm_block_validator *v,
225 				 struct dm_block *b,
226 				 size_t block_size)
227 {
228 	struct thin_disk_superblock *disk_super = dm_block_data(b);
229 
230 	disk_super->blocknr = cpu_to_le64(dm_block_location(b));
231 	disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
232 						      block_size - sizeof(__le32),
233 						      SUPERBLOCK_CSUM_XOR));
234 }
235 
236 static int sb_check(struct dm_block_validator *v,
237 		    struct dm_block *b,
238 		    size_t block_size)
239 {
240 	struct thin_disk_superblock *disk_super = dm_block_data(b);
241 	__le32 csum_le;
242 
243 	if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
244 		DMERR("sb_check failed: blocknr %llu: "
245 		      "wanted %llu", le64_to_cpu(disk_super->blocknr),
246 		      (unsigned long long)dm_block_location(b));
247 		return -ENOTBLK;
248 	}
249 
250 	if (le64_to_cpu(disk_super->magic) != THIN_SUPERBLOCK_MAGIC) {
251 		DMERR("sb_check failed: magic %llu: "
252 		      "wanted %llu", le64_to_cpu(disk_super->magic),
253 		      (unsigned long long)THIN_SUPERBLOCK_MAGIC);
254 		return -EILSEQ;
255 	}
256 
257 	csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
258 					     block_size - sizeof(__le32),
259 					     SUPERBLOCK_CSUM_XOR));
260 	if (csum_le != disk_super->csum) {
261 		DMERR("sb_check failed: csum %u: wanted %u",
262 		      le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
263 		return -EILSEQ;
264 	}
265 
266 	return 0;
267 }
268 
269 static struct dm_block_validator sb_validator = {
270 	.name = "superblock",
271 	.prepare_for_write = sb_prepare_for_write,
272 	.check = sb_check
273 };
274 
275 /*----------------------------------------------------------------
276  * Methods for the btree value types
277  *--------------------------------------------------------------*/
278 
279 static uint64_t pack_block_time(dm_block_t b, uint32_t t)
280 {
281 	return (b << 24) | t;
282 }
283 
284 static void unpack_block_time(uint64_t v, dm_block_t *b, uint32_t *t)
285 {
286 	*b = v >> 24;
287 	*t = v & ((1 << 24) - 1);
288 }
289 
290 static void data_block_inc(void *context, const void *value_le)
291 {
292 	struct dm_space_map *sm = context;
293 	__le64 v_le;
294 	uint64_t b;
295 	uint32_t t;
296 
297 	memcpy(&v_le, value_le, sizeof(v_le));
298 	unpack_block_time(le64_to_cpu(v_le), &b, &t);
299 	dm_sm_inc_block(sm, b);
300 }
301 
302 static void data_block_dec(void *context, const void *value_le)
303 {
304 	struct dm_space_map *sm = context;
305 	__le64 v_le;
306 	uint64_t b;
307 	uint32_t t;
308 
309 	memcpy(&v_le, value_le, sizeof(v_le));
310 	unpack_block_time(le64_to_cpu(v_le), &b, &t);
311 	dm_sm_dec_block(sm, b);
312 }
313 
314 static int data_block_equal(void *context, const void *value1_le, const void *value2_le)
315 {
316 	__le64 v1_le, v2_le;
317 	uint64_t b1, b2;
318 	uint32_t t;
319 
320 	memcpy(&v1_le, value1_le, sizeof(v1_le));
321 	memcpy(&v2_le, value2_le, sizeof(v2_le));
322 	unpack_block_time(le64_to_cpu(v1_le), &b1, &t);
323 	unpack_block_time(le64_to_cpu(v2_le), &b2, &t);
324 
325 	return b1 == b2;
326 }
327 
328 static void subtree_inc(void *context, const void *value)
329 {
330 	struct dm_btree_info *info = context;
331 	__le64 root_le;
332 	uint64_t root;
333 
334 	memcpy(&root_le, value, sizeof(root_le));
335 	root = le64_to_cpu(root_le);
336 	dm_tm_inc(info->tm, root);
337 }
338 
339 static void subtree_dec(void *context, const void *value)
340 {
341 	struct dm_btree_info *info = context;
342 	__le64 root_le;
343 	uint64_t root;
344 
345 	memcpy(&root_le, value, sizeof(root_le));
346 	root = le64_to_cpu(root_le);
347 	if (dm_btree_del(info, root))
348 		DMERR("btree delete failed\n");
349 }
350 
351 static int subtree_equal(void *context, const void *value1_le, const void *value2_le)
352 {
353 	__le64 v1_le, v2_le;
354 	memcpy(&v1_le, value1_le, sizeof(v1_le));
355 	memcpy(&v2_le, value2_le, sizeof(v2_le));
356 
357 	return v1_le == v2_le;
358 }
359 
360 /*----------------------------------------------------------------*/
361 
362 static int superblock_lock_zero(struct dm_pool_metadata *pmd,
363 				struct dm_block **sblock)
364 {
365 	return dm_bm_write_lock_zero(pmd->bm, THIN_SUPERBLOCK_LOCATION,
366 				     &sb_validator, sblock);
367 }
368 
369 static int superblock_lock(struct dm_pool_metadata *pmd,
370 			   struct dm_block **sblock)
371 {
372 	return dm_bm_write_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
373 				&sb_validator, sblock);
374 }
375 
376 static int __superblock_all_zeroes(struct dm_block_manager *bm, int *result)
377 {
378 	int r;
379 	unsigned i;
380 	struct dm_block *b;
381 	__le64 *data_le, zero = cpu_to_le64(0);
382 	unsigned block_size = dm_bm_block_size(bm) / sizeof(__le64);
383 
384 	/*
385 	 * We can't use a validator here - it may be all zeroes.
386 	 */
387 	r = dm_bm_read_lock(bm, THIN_SUPERBLOCK_LOCATION, NULL, &b);
388 	if (r)
389 		return r;
390 
391 	data_le = dm_block_data(b);
392 	*result = 1;
393 	for (i = 0; i < block_size; i++) {
394 		if (data_le[i] != zero) {
395 			*result = 0;
396 			break;
397 		}
398 	}
399 
400 	return dm_bm_unlock(b);
401 }
402 
403 static void __setup_btree_details(struct dm_pool_metadata *pmd)
404 {
405 	pmd->info.tm = pmd->tm;
406 	pmd->info.levels = 2;
407 	pmd->info.value_type.context = pmd->data_sm;
408 	pmd->info.value_type.size = sizeof(__le64);
409 	pmd->info.value_type.inc = data_block_inc;
410 	pmd->info.value_type.dec = data_block_dec;
411 	pmd->info.value_type.equal = data_block_equal;
412 
413 	memcpy(&pmd->nb_info, &pmd->info, sizeof(pmd->nb_info));
414 	pmd->nb_info.tm = pmd->nb_tm;
415 
416 	pmd->tl_info.tm = pmd->tm;
417 	pmd->tl_info.levels = 1;
418 	pmd->tl_info.value_type.context = &pmd->bl_info;
419 	pmd->tl_info.value_type.size = sizeof(__le64);
420 	pmd->tl_info.value_type.inc = subtree_inc;
421 	pmd->tl_info.value_type.dec = subtree_dec;
422 	pmd->tl_info.value_type.equal = subtree_equal;
423 
424 	pmd->bl_info.tm = pmd->tm;
425 	pmd->bl_info.levels = 1;
426 	pmd->bl_info.value_type.context = pmd->data_sm;
427 	pmd->bl_info.value_type.size = sizeof(__le64);
428 	pmd->bl_info.value_type.inc = data_block_inc;
429 	pmd->bl_info.value_type.dec = data_block_dec;
430 	pmd->bl_info.value_type.equal = data_block_equal;
431 
432 	pmd->details_info.tm = pmd->tm;
433 	pmd->details_info.levels = 1;
434 	pmd->details_info.value_type.context = NULL;
435 	pmd->details_info.value_type.size = sizeof(struct disk_device_details);
436 	pmd->details_info.value_type.inc = NULL;
437 	pmd->details_info.value_type.dec = NULL;
438 	pmd->details_info.value_type.equal = NULL;
439 }
440 
441 static int save_sm_roots(struct dm_pool_metadata *pmd)
442 {
443 	int r;
444 	size_t len;
445 
446 	r = dm_sm_root_size(pmd->metadata_sm, &len);
447 	if (r < 0)
448 		return r;
449 
450 	r = dm_sm_copy_root(pmd->metadata_sm, &pmd->metadata_space_map_root, len);
451 	if (r < 0)
452 		return r;
453 
454 	r = dm_sm_root_size(pmd->data_sm, &len);
455 	if (r < 0)
456 		return r;
457 
458 	return dm_sm_copy_root(pmd->data_sm, &pmd->data_space_map_root, len);
459 }
460 
461 static void copy_sm_roots(struct dm_pool_metadata *pmd,
462 			  struct thin_disk_superblock *disk)
463 {
464 	memcpy(&disk->metadata_space_map_root,
465 	       &pmd->metadata_space_map_root,
466 	       sizeof(pmd->metadata_space_map_root));
467 
468 	memcpy(&disk->data_space_map_root,
469 	       &pmd->data_space_map_root,
470 	       sizeof(pmd->data_space_map_root));
471 }
472 
473 static int __write_initial_superblock(struct dm_pool_metadata *pmd)
474 {
475 	int r;
476 	struct dm_block *sblock;
477 	struct thin_disk_superblock *disk_super;
478 	sector_t bdev_size = i_size_read(pmd->bdev->bd_inode) >> SECTOR_SHIFT;
479 
480 	if (bdev_size > THIN_METADATA_MAX_SECTORS)
481 		bdev_size = THIN_METADATA_MAX_SECTORS;
482 
483 	r = dm_sm_commit(pmd->data_sm);
484 	if (r < 0)
485 		return r;
486 
487 	r = save_sm_roots(pmd);
488 	if (r < 0)
489 		return r;
490 
491 	r = dm_tm_pre_commit(pmd->tm);
492 	if (r < 0)
493 		return r;
494 
495 	r = superblock_lock_zero(pmd, &sblock);
496 	if (r)
497 		return r;
498 
499 	disk_super = dm_block_data(sblock);
500 	disk_super->flags = 0;
501 	memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
502 	disk_super->magic = cpu_to_le64(THIN_SUPERBLOCK_MAGIC);
503 	disk_super->version = cpu_to_le32(THIN_VERSION);
504 	disk_super->time = 0;
505 	disk_super->trans_id = 0;
506 	disk_super->held_root = 0;
507 
508 	copy_sm_roots(pmd, disk_super);
509 
510 	disk_super->data_mapping_root = cpu_to_le64(pmd->root);
511 	disk_super->device_details_root = cpu_to_le64(pmd->details_root);
512 	disk_super->metadata_block_size = cpu_to_le32(THIN_METADATA_BLOCK_SIZE);
513 	disk_super->metadata_nr_blocks = cpu_to_le64(bdev_size >> SECTOR_TO_BLOCK_SHIFT);
514 	disk_super->data_block_size = cpu_to_le32(pmd->data_block_size);
515 
516 	return dm_tm_commit(pmd->tm, sblock);
517 }
518 
519 static int __format_metadata(struct dm_pool_metadata *pmd)
520 {
521 	int r;
522 
523 	r = dm_tm_create_with_sm(pmd->bm, THIN_SUPERBLOCK_LOCATION,
524 				 &pmd->tm, &pmd->metadata_sm);
525 	if (r < 0) {
526 		DMERR("tm_create_with_sm failed");
527 		return r;
528 	}
529 
530 	pmd->data_sm = dm_sm_disk_create(pmd->tm, 0);
531 	if (IS_ERR(pmd->data_sm)) {
532 		DMERR("sm_disk_create failed");
533 		r = PTR_ERR(pmd->data_sm);
534 		goto bad_cleanup_tm;
535 	}
536 
537 	pmd->nb_tm = dm_tm_create_non_blocking_clone(pmd->tm);
538 	if (!pmd->nb_tm) {
539 		DMERR("could not create non-blocking clone tm");
540 		r = -ENOMEM;
541 		goto bad_cleanup_data_sm;
542 	}
543 
544 	__setup_btree_details(pmd);
545 
546 	r = dm_btree_empty(&pmd->info, &pmd->root);
547 	if (r < 0)
548 		goto bad_cleanup_nb_tm;
549 
550 	r = dm_btree_empty(&pmd->details_info, &pmd->details_root);
551 	if (r < 0) {
552 		DMERR("couldn't create devices root");
553 		goto bad_cleanup_nb_tm;
554 	}
555 
556 	r = __write_initial_superblock(pmd);
557 	if (r)
558 		goto bad_cleanup_nb_tm;
559 
560 	return 0;
561 
562 bad_cleanup_nb_tm:
563 	dm_tm_destroy(pmd->nb_tm);
564 bad_cleanup_data_sm:
565 	dm_sm_destroy(pmd->data_sm);
566 bad_cleanup_tm:
567 	dm_tm_destroy(pmd->tm);
568 	dm_sm_destroy(pmd->metadata_sm);
569 
570 	return r;
571 }
572 
573 static int __check_incompat_features(struct thin_disk_superblock *disk_super,
574 				     struct dm_pool_metadata *pmd)
575 {
576 	uint32_t features;
577 
578 	features = le32_to_cpu(disk_super->incompat_flags) & ~THIN_FEATURE_INCOMPAT_SUPP;
579 	if (features) {
580 		DMERR("could not access metadata due to unsupported optional features (%lx).",
581 		      (unsigned long)features);
582 		return -EINVAL;
583 	}
584 
585 	/*
586 	 * Check for read-only metadata to skip the following RDWR checks.
587 	 */
588 	if (get_disk_ro(pmd->bdev->bd_disk))
589 		return 0;
590 
591 	features = le32_to_cpu(disk_super->compat_ro_flags) & ~THIN_FEATURE_COMPAT_RO_SUPP;
592 	if (features) {
593 		DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
594 		      (unsigned long)features);
595 		return -EINVAL;
596 	}
597 
598 	return 0;
599 }
600 
601 static int __open_metadata(struct dm_pool_metadata *pmd)
602 {
603 	int r;
604 	struct dm_block *sblock;
605 	struct thin_disk_superblock *disk_super;
606 
607 	r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
608 			    &sb_validator, &sblock);
609 	if (r < 0) {
610 		DMERR("couldn't read superblock");
611 		return r;
612 	}
613 
614 	disk_super = dm_block_data(sblock);
615 
616 	/* Verify the data block size hasn't changed */
617 	if (le32_to_cpu(disk_super->data_block_size) != pmd->data_block_size) {
618 		DMERR("changing the data block size (from %u to %llu) is not supported",
619 		      le32_to_cpu(disk_super->data_block_size),
620 		      (unsigned long long)pmd->data_block_size);
621 		r = -EINVAL;
622 		goto bad_unlock_sblock;
623 	}
624 
625 	r = __check_incompat_features(disk_super, pmd);
626 	if (r < 0)
627 		goto bad_unlock_sblock;
628 
629 	r = dm_tm_open_with_sm(pmd->bm, THIN_SUPERBLOCK_LOCATION,
630 			       disk_super->metadata_space_map_root,
631 			       sizeof(disk_super->metadata_space_map_root),
632 			       &pmd->tm, &pmd->metadata_sm);
633 	if (r < 0) {
634 		DMERR("tm_open_with_sm failed");
635 		goto bad_unlock_sblock;
636 	}
637 
638 	pmd->data_sm = dm_sm_disk_open(pmd->tm, disk_super->data_space_map_root,
639 				       sizeof(disk_super->data_space_map_root));
640 	if (IS_ERR(pmd->data_sm)) {
641 		DMERR("sm_disk_open failed");
642 		r = PTR_ERR(pmd->data_sm);
643 		goto bad_cleanup_tm;
644 	}
645 
646 	pmd->nb_tm = dm_tm_create_non_blocking_clone(pmd->tm);
647 	if (!pmd->nb_tm) {
648 		DMERR("could not create non-blocking clone tm");
649 		r = -ENOMEM;
650 		goto bad_cleanup_data_sm;
651 	}
652 
653 	__setup_btree_details(pmd);
654 	return dm_bm_unlock(sblock);
655 
656 bad_cleanup_data_sm:
657 	dm_sm_destroy(pmd->data_sm);
658 bad_cleanup_tm:
659 	dm_tm_destroy(pmd->tm);
660 	dm_sm_destroy(pmd->metadata_sm);
661 bad_unlock_sblock:
662 	dm_bm_unlock(sblock);
663 
664 	return r;
665 }
666 
667 static int __open_or_format_metadata(struct dm_pool_metadata *pmd, bool format_device)
668 {
669 	int r, unformatted;
670 
671 	r = __superblock_all_zeroes(pmd->bm, &unformatted);
672 	if (r)
673 		return r;
674 
675 	if (unformatted)
676 		return format_device ? __format_metadata(pmd) : -EPERM;
677 
678 	return __open_metadata(pmd);
679 }
680 
681 static int __create_persistent_data_objects(struct dm_pool_metadata *pmd, bool format_device)
682 {
683 	int r;
684 
685 	pmd->bm = dm_block_manager_create(pmd->bdev, THIN_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
686 					  THIN_METADATA_CACHE_SIZE,
687 					  THIN_MAX_CONCURRENT_LOCKS);
688 	if (IS_ERR(pmd->bm)) {
689 		DMERR("could not create block manager");
690 		return PTR_ERR(pmd->bm);
691 	}
692 
693 	r = __open_or_format_metadata(pmd, format_device);
694 	if (r)
695 		dm_block_manager_destroy(pmd->bm);
696 
697 	return r;
698 }
699 
700 static void __destroy_persistent_data_objects(struct dm_pool_metadata *pmd)
701 {
702 	dm_sm_destroy(pmd->data_sm);
703 	dm_sm_destroy(pmd->metadata_sm);
704 	dm_tm_destroy(pmd->nb_tm);
705 	dm_tm_destroy(pmd->tm);
706 	dm_block_manager_destroy(pmd->bm);
707 }
708 
709 static int __begin_transaction(struct dm_pool_metadata *pmd)
710 {
711 	int r;
712 	struct thin_disk_superblock *disk_super;
713 	struct dm_block *sblock;
714 
715 	/*
716 	 * We re-read the superblock every time.  Shouldn't need to do this
717 	 * really.
718 	 */
719 	r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
720 			    &sb_validator, &sblock);
721 	if (r)
722 		return r;
723 
724 	disk_super = dm_block_data(sblock);
725 	pmd->time = le32_to_cpu(disk_super->time);
726 	pmd->root = le64_to_cpu(disk_super->data_mapping_root);
727 	pmd->details_root = le64_to_cpu(disk_super->device_details_root);
728 	pmd->trans_id = le64_to_cpu(disk_super->trans_id);
729 	pmd->flags = le32_to_cpu(disk_super->flags);
730 	pmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
731 
732 	dm_bm_unlock(sblock);
733 	return 0;
734 }
735 
736 static int __write_changed_details(struct dm_pool_metadata *pmd)
737 {
738 	int r;
739 	struct dm_thin_device *td, *tmp;
740 	struct disk_device_details details;
741 	uint64_t key;
742 
743 	list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
744 		if (!td->changed)
745 			continue;
746 
747 		key = td->id;
748 
749 		details.mapped_blocks = cpu_to_le64(td->mapped_blocks);
750 		details.transaction_id = cpu_to_le64(td->transaction_id);
751 		details.creation_time = cpu_to_le32(td->creation_time);
752 		details.snapshotted_time = cpu_to_le32(td->snapshotted_time);
753 		__dm_bless_for_disk(&details);
754 
755 		r = dm_btree_insert(&pmd->details_info, pmd->details_root,
756 				    &key, &details, &pmd->details_root);
757 		if (r)
758 			return r;
759 
760 		if (td->open_count)
761 			td->changed = 0;
762 		else {
763 			list_del(&td->list);
764 			kfree(td);
765 		}
766 	}
767 
768 	return 0;
769 }
770 
771 static int __commit_transaction(struct dm_pool_metadata *pmd)
772 {
773 	int r;
774 	size_t metadata_len, data_len;
775 	struct thin_disk_superblock *disk_super;
776 	struct dm_block *sblock;
777 
778 	/*
779 	 * We need to know if the thin_disk_superblock exceeds a 512-byte sector.
780 	 */
781 	BUILD_BUG_ON(sizeof(struct thin_disk_superblock) > 512);
782 
783 	r = __write_changed_details(pmd);
784 	if (r < 0)
785 		return r;
786 
787 	r = dm_sm_commit(pmd->data_sm);
788 	if (r < 0)
789 		return r;
790 
791 	r = dm_tm_pre_commit(pmd->tm);
792 	if (r < 0)
793 		return r;
794 
795 	r = dm_sm_root_size(pmd->metadata_sm, &metadata_len);
796 	if (r < 0)
797 		return r;
798 
799 	r = dm_sm_root_size(pmd->data_sm, &data_len);
800 	if (r < 0)
801 		return r;
802 
803 	r = save_sm_roots(pmd);
804 	if (r < 0)
805 		return r;
806 
807 	r = superblock_lock(pmd, &sblock);
808 	if (r)
809 		return r;
810 
811 	disk_super = dm_block_data(sblock);
812 	disk_super->time = cpu_to_le32(pmd->time);
813 	disk_super->data_mapping_root = cpu_to_le64(pmd->root);
814 	disk_super->device_details_root = cpu_to_le64(pmd->details_root);
815 	disk_super->trans_id = cpu_to_le64(pmd->trans_id);
816 	disk_super->flags = cpu_to_le32(pmd->flags);
817 
818 	copy_sm_roots(pmd, disk_super);
819 
820 	return dm_tm_commit(pmd->tm, sblock);
821 }
822 
823 struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
824 					       sector_t data_block_size,
825 					       bool format_device)
826 {
827 	int r;
828 	struct dm_pool_metadata *pmd;
829 
830 	pmd = kmalloc(sizeof(*pmd), GFP_KERNEL);
831 	if (!pmd) {
832 		DMERR("could not allocate metadata struct");
833 		return ERR_PTR(-ENOMEM);
834 	}
835 
836 	init_rwsem(&pmd->root_lock);
837 	pmd->time = 0;
838 	INIT_LIST_HEAD(&pmd->thin_devices);
839 	pmd->read_only = false;
840 	pmd->fail_io = false;
841 	pmd->bdev = bdev;
842 	pmd->data_block_size = data_block_size;
843 
844 	r = __create_persistent_data_objects(pmd, format_device);
845 	if (r) {
846 		kfree(pmd);
847 		return ERR_PTR(r);
848 	}
849 
850 	r = __begin_transaction(pmd);
851 	if (r < 0) {
852 		if (dm_pool_metadata_close(pmd) < 0)
853 			DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
854 		return ERR_PTR(r);
855 	}
856 
857 	return pmd;
858 }
859 
860 int dm_pool_metadata_close(struct dm_pool_metadata *pmd)
861 {
862 	int r;
863 	unsigned open_devices = 0;
864 	struct dm_thin_device *td, *tmp;
865 
866 	down_read(&pmd->root_lock);
867 	list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
868 		if (td->open_count)
869 			open_devices++;
870 		else {
871 			list_del(&td->list);
872 			kfree(td);
873 		}
874 	}
875 	up_read(&pmd->root_lock);
876 
877 	if (open_devices) {
878 		DMERR("attempt to close pmd when %u device(s) are still open",
879 		       open_devices);
880 		return -EBUSY;
881 	}
882 
883 	if (!pmd->read_only && !pmd->fail_io) {
884 		r = __commit_transaction(pmd);
885 		if (r < 0)
886 			DMWARN("%s: __commit_transaction() failed, error = %d",
887 			       __func__, r);
888 	}
889 
890 	if (!pmd->fail_io)
891 		__destroy_persistent_data_objects(pmd);
892 
893 	kfree(pmd);
894 	return 0;
895 }
896 
897 /*
898  * __open_device: Returns @td corresponding to device with id @dev,
899  * creating it if @create is set and incrementing @td->open_count.
900  * On failure, @td is undefined.
901  */
902 static int __open_device(struct dm_pool_metadata *pmd,
903 			 dm_thin_id dev, int create,
904 			 struct dm_thin_device **td)
905 {
906 	int r, changed = 0;
907 	struct dm_thin_device *td2;
908 	uint64_t key = dev;
909 	struct disk_device_details details_le;
910 
911 	/*
912 	 * If the device is already open, return it.
913 	 */
914 	list_for_each_entry(td2, &pmd->thin_devices, list)
915 		if (td2->id == dev) {
916 			/*
917 			 * May not create an already-open device.
918 			 */
919 			if (create)
920 				return -EEXIST;
921 
922 			td2->open_count++;
923 			*td = td2;
924 			return 0;
925 		}
926 
927 	/*
928 	 * Check the device exists.
929 	 */
930 	r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
931 			    &key, &details_le);
932 	if (r) {
933 		if (r != -ENODATA || !create)
934 			return r;
935 
936 		/*
937 		 * Create new device.
938 		 */
939 		changed = 1;
940 		details_le.mapped_blocks = 0;
941 		details_le.transaction_id = cpu_to_le64(pmd->trans_id);
942 		details_le.creation_time = cpu_to_le32(pmd->time);
943 		details_le.snapshotted_time = cpu_to_le32(pmd->time);
944 	}
945 
946 	*td = kmalloc(sizeof(**td), GFP_NOIO);
947 	if (!*td)
948 		return -ENOMEM;
949 
950 	(*td)->pmd = pmd;
951 	(*td)->id = dev;
952 	(*td)->open_count = 1;
953 	(*td)->changed = changed;
954 	(*td)->aborted_with_changes = false;
955 	(*td)->mapped_blocks = le64_to_cpu(details_le.mapped_blocks);
956 	(*td)->transaction_id = le64_to_cpu(details_le.transaction_id);
957 	(*td)->creation_time = le32_to_cpu(details_le.creation_time);
958 	(*td)->snapshotted_time = le32_to_cpu(details_le.snapshotted_time);
959 
960 	list_add(&(*td)->list, &pmd->thin_devices);
961 
962 	return 0;
963 }
964 
965 static void __close_device(struct dm_thin_device *td)
966 {
967 	--td->open_count;
968 }
969 
970 static int __create_thin(struct dm_pool_metadata *pmd,
971 			 dm_thin_id dev)
972 {
973 	int r;
974 	dm_block_t dev_root;
975 	uint64_t key = dev;
976 	struct disk_device_details details_le;
977 	struct dm_thin_device *td;
978 	__le64 value;
979 
980 	r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
981 			    &key, &details_le);
982 	if (!r)
983 		return -EEXIST;
984 
985 	/*
986 	 * Create an empty btree for the mappings.
987 	 */
988 	r = dm_btree_empty(&pmd->bl_info, &dev_root);
989 	if (r)
990 		return r;
991 
992 	/*
993 	 * Insert it into the main mapping tree.
994 	 */
995 	value = cpu_to_le64(dev_root);
996 	__dm_bless_for_disk(&value);
997 	r = dm_btree_insert(&pmd->tl_info, pmd->root, &key, &value, &pmd->root);
998 	if (r) {
999 		dm_btree_del(&pmd->bl_info, dev_root);
1000 		return r;
1001 	}
1002 
1003 	r = __open_device(pmd, dev, 1, &td);
1004 	if (r) {
1005 		dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
1006 		dm_btree_del(&pmd->bl_info, dev_root);
1007 		return r;
1008 	}
1009 	__close_device(td);
1010 
1011 	return r;
1012 }
1013 
1014 int dm_pool_create_thin(struct dm_pool_metadata *pmd, dm_thin_id dev)
1015 {
1016 	int r = -EINVAL;
1017 
1018 	down_write(&pmd->root_lock);
1019 	if (!pmd->fail_io)
1020 		r = __create_thin(pmd, dev);
1021 	up_write(&pmd->root_lock);
1022 
1023 	return r;
1024 }
1025 
1026 static int __set_snapshot_details(struct dm_pool_metadata *pmd,
1027 				  struct dm_thin_device *snap,
1028 				  dm_thin_id origin, uint32_t time)
1029 {
1030 	int r;
1031 	struct dm_thin_device *td;
1032 
1033 	r = __open_device(pmd, origin, 0, &td);
1034 	if (r)
1035 		return r;
1036 
1037 	td->changed = 1;
1038 	td->snapshotted_time = time;
1039 
1040 	snap->mapped_blocks = td->mapped_blocks;
1041 	snap->snapshotted_time = time;
1042 	__close_device(td);
1043 
1044 	return 0;
1045 }
1046 
1047 static int __create_snap(struct dm_pool_metadata *pmd,
1048 			 dm_thin_id dev, dm_thin_id origin)
1049 {
1050 	int r;
1051 	dm_block_t origin_root;
1052 	uint64_t key = origin, dev_key = dev;
1053 	struct dm_thin_device *td;
1054 	struct disk_device_details details_le;
1055 	__le64 value;
1056 
1057 	/* check this device is unused */
1058 	r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
1059 			    &dev_key, &details_le);
1060 	if (!r)
1061 		return -EEXIST;
1062 
1063 	/* find the mapping tree for the origin */
1064 	r = dm_btree_lookup(&pmd->tl_info, pmd->root, &key, &value);
1065 	if (r)
1066 		return r;
1067 	origin_root = le64_to_cpu(value);
1068 
1069 	/* clone the origin, an inc will do */
1070 	dm_tm_inc(pmd->tm, origin_root);
1071 
1072 	/* insert into the main mapping tree */
1073 	value = cpu_to_le64(origin_root);
1074 	__dm_bless_for_disk(&value);
1075 	key = dev;
1076 	r = dm_btree_insert(&pmd->tl_info, pmd->root, &key, &value, &pmd->root);
1077 	if (r) {
1078 		dm_tm_dec(pmd->tm, origin_root);
1079 		return r;
1080 	}
1081 
1082 	pmd->time++;
1083 
1084 	r = __open_device(pmd, dev, 1, &td);
1085 	if (r)
1086 		goto bad;
1087 
1088 	r = __set_snapshot_details(pmd, td, origin, pmd->time);
1089 	__close_device(td);
1090 
1091 	if (r)
1092 		goto bad;
1093 
1094 	return 0;
1095 
1096 bad:
1097 	dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
1098 	dm_btree_remove(&pmd->details_info, pmd->details_root,
1099 			&key, &pmd->details_root);
1100 	return r;
1101 }
1102 
1103 int dm_pool_create_snap(struct dm_pool_metadata *pmd,
1104 				 dm_thin_id dev,
1105 				 dm_thin_id origin)
1106 {
1107 	int r = -EINVAL;
1108 
1109 	down_write(&pmd->root_lock);
1110 	if (!pmd->fail_io)
1111 		r = __create_snap(pmd, dev, origin);
1112 	up_write(&pmd->root_lock);
1113 
1114 	return r;
1115 }
1116 
1117 static int __delete_device(struct dm_pool_metadata *pmd, dm_thin_id dev)
1118 {
1119 	int r;
1120 	uint64_t key = dev;
1121 	struct dm_thin_device *td;
1122 
1123 	/* TODO: failure should mark the transaction invalid */
1124 	r = __open_device(pmd, dev, 0, &td);
1125 	if (r)
1126 		return r;
1127 
1128 	if (td->open_count > 1) {
1129 		__close_device(td);
1130 		return -EBUSY;
1131 	}
1132 
1133 	list_del(&td->list);
1134 	kfree(td);
1135 	r = dm_btree_remove(&pmd->details_info, pmd->details_root,
1136 			    &key, &pmd->details_root);
1137 	if (r)
1138 		return r;
1139 
1140 	r = dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
1141 	if (r)
1142 		return r;
1143 
1144 	return 0;
1145 }
1146 
1147 int dm_pool_delete_thin_device(struct dm_pool_metadata *pmd,
1148 			       dm_thin_id dev)
1149 {
1150 	int r = -EINVAL;
1151 
1152 	down_write(&pmd->root_lock);
1153 	if (!pmd->fail_io)
1154 		r = __delete_device(pmd, dev);
1155 	up_write(&pmd->root_lock);
1156 
1157 	return r;
1158 }
1159 
1160 int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
1161 					uint64_t current_id,
1162 					uint64_t new_id)
1163 {
1164 	int r = -EINVAL;
1165 
1166 	down_write(&pmd->root_lock);
1167 
1168 	if (pmd->fail_io)
1169 		goto out;
1170 
1171 	if (pmd->trans_id != current_id) {
1172 		DMERR("mismatched transaction id");
1173 		goto out;
1174 	}
1175 
1176 	pmd->trans_id = new_id;
1177 	r = 0;
1178 
1179 out:
1180 	up_write(&pmd->root_lock);
1181 
1182 	return r;
1183 }
1184 
1185 int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
1186 					uint64_t *result)
1187 {
1188 	int r = -EINVAL;
1189 
1190 	down_read(&pmd->root_lock);
1191 	if (!pmd->fail_io) {
1192 		*result = pmd->trans_id;
1193 		r = 0;
1194 	}
1195 	up_read(&pmd->root_lock);
1196 
1197 	return r;
1198 }
1199 
1200 static int __reserve_metadata_snap(struct dm_pool_metadata *pmd)
1201 {
1202 	int r, inc;
1203 	struct thin_disk_superblock *disk_super;
1204 	struct dm_block *copy, *sblock;
1205 	dm_block_t held_root;
1206 
1207 	/*
1208 	 * Copy the superblock.
1209 	 */
1210 	dm_sm_inc_block(pmd->metadata_sm, THIN_SUPERBLOCK_LOCATION);
1211 	r = dm_tm_shadow_block(pmd->tm, THIN_SUPERBLOCK_LOCATION,
1212 			       &sb_validator, &copy, &inc);
1213 	if (r)
1214 		return r;
1215 
1216 	BUG_ON(!inc);
1217 
1218 	held_root = dm_block_location(copy);
1219 	disk_super = dm_block_data(copy);
1220 
1221 	if (le64_to_cpu(disk_super->held_root)) {
1222 		DMWARN("Pool metadata snapshot already exists: release this before taking another.");
1223 
1224 		dm_tm_dec(pmd->tm, held_root);
1225 		dm_tm_unlock(pmd->tm, copy);
1226 		return -EBUSY;
1227 	}
1228 
1229 	/*
1230 	 * Wipe the spacemap since we're not publishing this.
1231 	 */
1232 	memset(&disk_super->data_space_map_root, 0,
1233 	       sizeof(disk_super->data_space_map_root));
1234 	memset(&disk_super->metadata_space_map_root, 0,
1235 	       sizeof(disk_super->metadata_space_map_root));
1236 
1237 	/*
1238 	 * Increment the data structures that need to be preserved.
1239 	 */
1240 	dm_tm_inc(pmd->tm, le64_to_cpu(disk_super->data_mapping_root));
1241 	dm_tm_inc(pmd->tm, le64_to_cpu(disk_super->device_details_root));
1242 	dm_tm_unlock(pmd->tm, copy);
1243 
1244 	/*
1245 	 * Write the held root into the superblock.
1246 	 */
1247 	r = superblock_lock(pmd, &sblock);
1248 	if (r) {
1249 		dm_tm_dec(pmd->tm, held_root);
1250 		return r;
1251 	}
1252 
1253 	disk_super = dm_block_data(sblock);
1254 	disk_super->held_root = cpu_to_le64(held_root);
1255 	dm_bm_unlock(sblock);
1256 	return 0;
1257 }
1258 
1259 int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd)
1260 {
1261 	int r = -EINVAL;
1262 
1263 	down_write(&pmd->root_lock);
1264 	if (!pmd->fail_io)
1265 		r = __reserve_metadata_snap(pmd);
1266 	up_write(&pmd->root_lock);
1267 
1268 	return r;
1269 }
1270 
1271 static int __release_metadata_snap(struct dm_pool_metadata *pmd)
1272 {
1273 	int r;
1274 	struct thin_disk_superblock *disk_super;
1275 	struct dm_block *sblock, *copy;
1276 	dm_block_t held_root;
1277 
1278 	r = superblock_lock(pmd, &sblock);
1279 	if (r)
1280 		return r;
1281 
1282 	disk_super = dm_block_data(sblock);
1283 	held_root = le64_to_cpu(disk_super->held_root);
1284 	disk_super->held_root = cpu_to_le64(0);
1285 
1286 	dm_bm_unlock(sblock);
1287 
1288 	if (!held_root) {
1289 		DMWARN("No pool metadata snapshot found: nothing to release.");
1290 		return -EINVAL;
1291 	}
1292 
1293 	r = dm_tm_read_lock(pmd->tm, held_root, &sb_validator, &copy);
1294 	if (r)
1295 		return r;
1296 
1297 	disk_super = dm_block_data(copy);
1298 	dm_sm_dec_block(pmd->metadata_sm, le64_to_cpu(disk_super->data_mapping_root));
1299 	dm_sm_dec_block(pmd->metadata_sm, le64_to_cpu(disk_super->device_details_root));
1300 	dm_sm_dec_block(pmd->metadata_sm, held_root);
1301 
1302 	return dm_tm_unlock(pmd->tm, copy);
1303 }
1304 
1305 int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd)
1306 {
1307 	int r = -EINVAL;
1308 
1309 	down_write(&pmd->root_lock);
1310 	if (!pmd->fail_io)
1311 		r = __release_metadata_snap(pmd);
1312 	up_write(&pmd->root_lock);
1313 
1314 	return r;
1315 }
1316 
1317 static int __get_metadata_snap(struct dm_pool_metadata *pmd,
1318 			       dm_block_t *result)
1319 {
1320 	int r;
1321 	struct thin_disk_superblock *disk_super;
1322 	struct dm_block *sblock;
1323 
1324 	r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
1325 			    &sb_validator, &sblock);
1326 	if (r)
1327 		return r;
1328 
1329 	disk_super = dm_block_data(sblock);
1330 	*result = le64_to_cpu(disk_super->held_root);
1331 
1332 	return dm_bm_unlock(sblock);
1333 }
1334 
1335 int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd,
1336 			      dm_block_t *result)
1337 {
1338 	int r = -EINVAL;
1339 
1340 	down_read(&pmd->root_lock);
1341 	if (!pmd->fail_io)
1342 		r = __get_metadata_snap(pmd, result);
1343 	up_read(&pmd->root_lock);
1344 
1345 	return r;
1346 }
1347 
1348 int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
1349 			     struct dm_thin_device **td)
1350 {
1351 	int r = -EINVAL;
1352 
1353 	down_write(&pmd->root_lock);
1354 	if (!pmd->fail_io)
1355 		r = __open_device(pmd, dev, 0, td);
1356 	up_write(&pmd->root_lock);
1357 
1358 	return r;
1359 }
1360 
1361 int dm_pool_close_thin_device(struct dm_thin_device *td)
1362 {
1363 	down_write(&td->pmd->root_lock);
1364 	__close_device(td);
1365 	up_write(&td->pmd->root_lock);
1366 
1367 	return 0;
1368 }
1369 
1370 dm_thin_id dm_thin_dev_id(struct dm_thin_device *td)
1371 {
1372 	return td->id;
1373 }
1374 
1375 /*
1376  * Check whether @time (of block creation) is older than @td's last snapshot.
1377  * If so then the associated block is shared with the last snapshot device.
1378  * Any block on a device created *after* the device last got snapshotted is
1379  * necessarily not shared.
1380  */
1381 static bool __snapshotted_since(struct dm_thin_device *td, uint32_t time)
1382 {
1383 	return td->snapshotted_time > time;
1384 }
1385 
1386 int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
1387 		       int can_block, struct dm_thin_lookup_result *result)
1388 {
1389 	int r = -EINVAL;
1390 	uint64_t block_time = 0;
1391 	__le64 value;
1392 	struct dm_pool_metadata *pmd = td->pmd;
1393 	dm_block_t keys[2] = { td->id, block };
1394 	struct dm_btree_info *info;
1395 
1396 	if (can_block) {
1397 		down_read(&pmd->root_lock);
1398 		info = &pmd->info;
1399 	} else if (down_read_trylock(&pmd->root_lock))
1400 		info = &pmd->nb_info;
1401 	else
1402 		return -EWOULDBLOCK;
1403 
1404 	if (pmd->fail_io)
1405 		goto out;
1406 
1407 	r = dm_btree_lookup(info, pmd->root, keys, &value);
1408 	if (!r)
1409 		block_time = le64_to_cpu(value);
1410 
1411 out:
1412 	up_read(&pmd->root_lock);
1413 
1414 	if (!r) {
1415 		dm_block_t exception_block;
1416 		uint32_t exception_time;
1417 		unpack_block_time(block_time, &exception_block,
1418 				  &exception_time);
1419 		result->block = exception_block;
1420 		result->shared = __snapshotted_since(td, exception_time);
1421 	}
1422 
1423 	return r;
1424 }
1425 
1426 static int __insert(struct dm_thin_device *td, dm_block_t block,
1427 		    dm_block_t data_block)
1428 {
1429 	int r, inserted;
1430 	__le64 value;
1431 	struct dm_pool_metadata *pmd = td->pmd;
1432 	dm_block_t keys[2] = { td->id, block };
1433 
1434 	value = cpu_to_le64(pack_block_time(data_block, pmd->time));
1435 	__dm_bless_for_disk(&value);
1436 
1437 	r = dm_btree_insert_notify(&pmd->info, pmd->root, keys, &value,
1438 				   &pmd->root, &inserted);
1439 	if (r)
1440 		return r;
1441 
1442 	td->changed = 1;
1443 	if (inserted)
1444 		td->mapped_blocks++;
1445 
1446 	return 0;
1447 }
1448 
1449 int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
1450 			 dm_block_t data_block)
1451 {
1452 	int r = -EINVAL;
1453 
1454 	down_write(&td->pmd->root_lock);
1455 	if (!td->pmd->fail_io)
1456 		r = __insert(td, block, data_block);
1457 	up_write(&td->pmd->root_lock);
1458 
1459 	return r;
1460 }
1461 
1462 static int __remove(struct dm_thin_device *td, dm_block_t block)
1463 {
1464 	int r;
1465 	struct dm_pool_metadata *pmd = td->pmd;
1466 	dm_block_t keys[2] = { td->id, block };
1467 
1468 	r = dm_btree_remove(&pmd->info, pmd->root, keys, &pmd->root);
1469 	if (r)
1470 		return r;
1471 
1472 	td->mapped_blocks--;
1473 	td->changed = 1;
1474 
1475 	return 0;
1476 }
1477 
1478 int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block)
1479 {
1480 	int r = -EINVAL;
1481 
1482 	down_write(&td->pmd->root_lock);
1483 	if (!td->pmd->fail_io)
1484 		r = __remove(td, block);
1485 	up_write(&td->pmd->root_lock);
1486 
1487 	return r;
1488 }
1489 
1490 int dm_pool_block_is_used(struct dm_pool_metadata *pmd, dm_block_t b, bool *result)
1491 {
1492 	int r;
1493 	uint32_t ref_count;
1494 
1495 	down_read(&pmd->root_lock);
1496 	r = dm_sm_get_count(pmd->data_sm, b, &ref_count);
1497 	if (!r)
1498 		*result = (ref_count != 0);
1499 	up_read(&pmd->root_lock);
1500 
1501 	return r;
1502 }
1503 
1504 bool dm_thin_changed_this_transaction(struct dm_thin_device *td)
1505 {
1506 	int r;
1507 
1508 	down_read(&td->pmd->root_lock);
1509 	r = td->changed;
1510 	up_read(&td->pmd->root_lock);
1511 
1512 	return r;
1513 }
1514 
1515 bool dm_pool_changed_this_transaction(struct dm_pool_metadata *pmd)
1516 {
1517 	bool r = false;
1518 	struct dm_thin_device *td, *tmp;
1519 
1520 	down_read(&pmd->root_lock);
1521 	list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
1522 		if (td->changed) {
1523 			r = td->changed;
1524 			break;
1525 		}
1526 	}
1527 	up_read(&pmd->root_lock);
1528 
1529 	return r;
1530 }
1531 
1532 bool dm_thin_aborted_changes(struct dm_thin_device *td)
1533 {
1534 	bool r;
1535 
1536 	down_read(&td->pmd->root_lock);
1537 	r = td->aborted_with_changes;
1538 	up_read(&td->pmd->root_lock);
1539 
1540 	return r;
1541 }
1542 
1543 int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result)
1544 {
1545 	int r = -EINVAL;
1546 
1547 	down_write(&pmd->root_lock);
1548 	if (!pmd->fail_io)
1549 		r = dm_sm_new_block(pmd->data_sm, result);
1550 	up_write(&pmd->root_lock);
1551 
1552 	return r;
1553 }
1554 
1555 int dm_pool_commit_metadata(struct dm_pool_metadata *pmd)
1556 {
1557 	int r = -EINVAL;
1558 
1559 	down_write(&pmd->root_lock);
1560 	if (pmd->fail_io)
1561 		goto out;
1562 
1563 	r = __commit_transaction(pmd);
1564 	if (r <= 0)
1565 		goto out;
1566 
1567 	/*
1568 	 * Open the next transaction.
1569 	 */
1570 	r = __begin_transaction(pmd);
1571 out:
1572 	up_write(&pmd->root_lock);
1573 	return r;
1574 }
1575 
1576 static void __set_abort_with_changes_flags(struct dm_pool_metadata *pmd)
1577 {
1578 	struct dm_thin_device *td;
1579 
1580 	list_for_each_entry(td, &pmd->thin_devices, list)
1581 		td->aborted_with_changes = td->changed;
1582 }
1583 
1584 int dm_pool_abort_metadata(struct dm_pool_metadata *pmd)
1585 {
1586 	int r = -EINVAL;
1587 
1588 	down_write(&pmd->root_lock);
1589 	if (pmd->fail_io)
1590 		goto out;
1591 
1592 	__set_abort_with_changes_flags(pmd);
1593 	__destroy_persistent_data_objects(pmd);
1594 	r = __create_persistent_data_objects(pmd, false);
1595 	if (r)
1596 		pmd->fail_io = true;
1597 
1598 out:
1599 	up_write(&pmd->root_lock);
1600 
1601 	return r;
1602 }
1603 
1604 int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd, dm_block_t *result)
1605 {
1606 	int r = -EINVAL;
1607 
1608 	down_read(&pmd->root_lock);
1609 	if (!pmd->fail_io)
1610 		r = dm_sm_get_nr_free(pmd->data_sm, result);
1611 	up_read(&pmd->root_lock);
1612 
1613 	return r;
1614 }
1615 
1616 int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
1617 					  dm_block_t *result)
1618 {
1619 	int r = -EINVAL;
1620 
1621 	down_read(&pmd->root_lock);
1622 	if (!pmd->fail_io)
1623 		r = dm_sm_get_nr_free(pmd->metadata_sm, result);
1624 	up_read(&pmd->root_lock);
1625 
1626 	return r;
1627 }
1628 
1629 int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
1630 				  dm_block_t *result)
1631 {
1632 	int r = -EINVAL;
1633 
1634 	down_read(&pmd->root_lock);
1635 	if (!pmd->fail_io)
1636 		r = dm_sm_get_nr_blocks(pmd->metadata_sm, result);
1637 	up_read(&pmd->root_lock);
1638 
1639 	return r;
1640 }
1641 
1642 int dm_pool_get_data_block_size(struct dm_pool_metadata *pmd, sector_t *result)
1643 {
1644 	down_read(&pmd->root_lock);
1645 	*result = pmd->data_block_size;
1646 	up_read(&pmd->root_lock);
1647 
1648 	return 0;
1649 }
1650 
1651 int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result)
1652 {
1653 	int r = -EINVAL;
1654 
1655 	down_read(&pmd->root_lock);
1656 	if (!pmd->fail_io)
1657 		r = dm_sm_get_nr_blocks(pmd->data_sm, result);
1658 	up_read(&pmd->root_lock);
1659 
1660 	return r;
1661 }
1662 
1663 int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result)
1664 {
1665 	int r = -EINVAL;
1666 	struct dm_pool_metadata *pmd = td->pmd;
1667 
1668 	down_read(&pmd->root_lock);
1669 	if (!pmd->fail_io) {
1670 		*result = td->mapped_blocks;
1671 		r = 0;
1672 	}
1673 	up_read(&pmd->root_lock);
1674 
1675 	return r;
1676 }
1677 
1678 static int __highest_block(struct dm_thin_device *td, dm_block_t *result)
1679 {
1680 	int r;
1681 	__le64 value_le;
1682 	dm_block_t thin_root;
1683 	struct dm_pool_metadata *pmd = td->pmd;
1684 
1685 	r = dm_btree_lookup(&pmd->tl_info, pmd->root, &td->id, &value_le);
1686 	if (r)
1687 		return r;
1688 
1689 	thin_root = le64_to_cpu(value_le);
1690 
1691 	return dm_btree_find_highest_key(&pmd->bl_info, thin_root, result);
1692 }
1693 
1694 int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
1695 				     dm_block_t *result)
1696 {
1697 	int r = -EINVAL;
1698 	struct dm_pool_metadata *pmd = td->pmd;
1699 
1700 	down_read(&pmd->root_lock);
1701 	if (!pmd->fail_io)
1702 		r = __highest_block(td, result);
1703 	up_read(&pmd->root_lock);
1704 
1705 	return r;
1706 }
1707 
1708 static int __resize_space_map(struct dm_space_map *sm, dm_block_t new_count)
1709 {
1710 	int r;
1711 	dm_block_t old_count;
1712 
1713 	r = dm_sm_get_nr_blocks(sm, &old_count);
1714 	if (r)
1715 		return r;
1716 
1717 	if (new_count == old_count)
1718 		return 0;
1719 
1720 	if (new_count < old_count) {
1721 		DMERR("cannot reduce size of space map");
1722 		return -EINVAL;
1723 	}
1724 
1725 	return dm_sm_extend(sm, new_count - old_count);
1726 }
1727 
1728 int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
1729 {
1730 	int r = -EINVAL;
1731 
1732 	down_write(&pmd->root_lock);
1733 	if (!pmd->fail_io)
1734 		r = __resize_space_map(pmd->data_sm, new_count);
1735 	up_write(&pmd->root_lock);
1736 
1737 	return r;
1738 }
1739 
1740 int dm_pool_resize_metadata_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
1741 {
1742 	int r = -EINVAL;
1743 
1744 	down_write(&pmd->root_lock);
1745 	if (!pmd->fail_io)
1746 		r = __resize_space_map(pmd->metadata_sm, new_count);
1747 	up_write(&pmd->root_lock);
1748 
1749 	return r;
1750 }
1751 
1752 void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd)
1753 {
1754 	down_write(&pmd->root_lock);
1755 	pmd->read_only = true;
1756 	dm_bm_set_read_only(pmd->bm);
1757 	up_write(&pmd->root_lock);
1758 }
1759 
1760 void dm_pool_metadata_read_write(struct dm_pool_metadata *pmd)
1761 {
1762 	down_write(&pmd->root_lock);
1763 	pmd->read_only = false;
1764 	dm_bm_set_read_write(pmd->bm);
1765 	up_write(&pmd->root_lock);
1766 }
1767 
1768 int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
1769 					dm_block_t threshold,
1770 					dm_sm_threshold_fn fn,
1771 					void *context)
1772 {
1773 	int r;
1774 
1775 	down_write(&pmd->root_lock);
1776 	r = dm_sm_register_threshold_callback(pmd->metadata_sm, threshold, fn, context);
1777 	up_write(&pmd->root_lock);
1778 
1779 	return r;
1780 }
1781 
1782 int dm_pool_metadata_set_needs_check(struct dm_pool_metadata *pmd)
1783 {
1784 	int r;
1785 	struct dm_block *sblock;
1786 	struct thin_disk_superblock *disk_super;
1787 
1788 	down_write(&pmd->root_lock);
1789 	pmd->flags |= THIN_METADATA_NEEDS_CHECK_FLAG;
1790 
1791 	r = superblock_lock(pmd, &sblock);
1792 	if (r) {
1793 		DMERR("couldn't read superblock");
1794 		goto out;
1795 	}
1796 
1797 	disk_super = dm_block_data(sblock);
1798 	disk_super->flags = cpu_to_le32(pmd->flags);
1799 
1800 	dm_bm_unlock(sblock);
1801 out:
1802 	up_write(&pmd->root_lock);
1803 	return r;
1804 }
1805 
1806 bool dm_pool_metadata_needs_check(struct dm_pool_metadata *pmd)
1807 {
1808 	bool needs_check;
1809 
1810 	down_read(&pmd->root_lock);
1811 	needs_check = pmd->flags & THIN_METADATA_NEEDS_CHECK_FLAG;
1812 	up_read(&pmd->root_lock);
1813 
1814 	return needs_check;
1815 }
1816