PPC: e500mc: add missing IVORs to bitmap
[qemu.git] / block / qcow2-refcount.c
1 /*
2 * Block driver for the QCOW version 2 format
3 *
4 * Copyright (c) 2004-2006 Fabrice Bellard
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24
25 #include "qemu-common.h"
26 #include "block_int.h"
27 #include "block/qcow2.h"
28
29 static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size);
30 static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
31 int64_t offset, int64_t length,
32 int addend);
33
34
35 /*********************************************************/
36 /* refcount handling */
37
38 int qcow2_refcount_init(BlockDriverState *bs)
39 {
40 BDRVQcowState *s = bs->opaque;
41 int ret, refcount_table_size2, i;
42
43 refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t);
44 s->refcount_table = g_malloc(refcount_table_size2);
45 if (s->refcount_table_size > 0) {
46 BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_LOAD);
47 ret = bdrv_pread(bs->file, s->refcount_table_offset,
48 s->refcount_table, refcount_table_size2);
49 if (ret != refcount_table_size2)
50 goto fail;
51 for(i = 0; i < s->refcount_table_size; i++)
52 be64_to_cpus(&s->refcount_table[i]);
53 }
54 return 0;
55 fail:
56 return -ENOMEM;
57 }
58
59 void qcow2_refcount_close(BlockDriverState *bs)
60 {
61 BDRVQcowState *s = bs->opaque;
62 g_free(s->refcount_table);
63 }
64
65
66 static int load_refcount_block(BlockDriverState *bs,
67 int64_t refcount_block_offset,
68 void **refcount_block)
69 {
70 BDRVQcowState *s = bs->opaque;
71 int ret;
72
73 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_LOAD);
74 ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset,
75 refcount_block);
76
77 return ret;
78 }
79
80 /*
81 * Returns the refcount of the cluster given by its index. Any non-negative
82 * return value is the refcount of the cluster, negative values are -errno
83 * and indicate an error.
84 */
85 static int get_refcount(BlockDriverState *bs, int64_t cluster_index)
86 {
87 BDRVQcowState *s = bs->opaque;
88 int refcount_table_index, block_index;
89 int64_t refcount_block_offset;
90 int ret;
91 uint16_t *refcount_block;
92 uint16_t refcount;
93
94 refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT);
95 if (refcount_table_index >= s->refcount_table_size)
96 return 0;
97 refcount_block_offset = s->refcount_table[refcount_table_index];
98 if (!refcount_block_offset)
99 return 0;
100
101 ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset,
102 (void**) &refcount_block);
103 if (ret < 0) {
104 return ret;
105 }
106
107 block_index = cluster_index &
108 ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
109 refcount = be16_to_cpu(refcount_block[block_index]);
110
111 ret = qcow2_cache_put(bs, s->refcount_block_cache,
112 (void**) &refcount_block);
113 if (ret < 0) {
114 return ret;
115 }
116
117 return refcount;
118 }
119
120 /*
121 * Rounds the refcount table size up to avoid growing the table for each single
122 * refcount block that is allocated.
123 */
124 static unsigned int next_refcount_table_size(BDRVQcowState *s,
125 unsigned int min_size)
126 {
127 unsigned int min_clusters = (min_size >> (s->cluster_bits - 3)) + 1;
128 unsigned int refcount_table_clusters =
129 MAX(1, s->refcount_table_size >> (s->cluster_bits - 3));
130
131 while (min_clusters > refcount_table_clusters) {
132 refcount_table_clusters = (refcount_table_clusters * 3 + 1) / 2;
133 }
134
135 return refcount_table_clusters << (s->cluster_bits - 3);
136 }
137
138
139 /* Checks if two offsets are described by the same refcount block */
140 static int in_same_refcount_block(BDRVQcowState *s, uint64_t offset_a,
141 uint64_t offset_b)
142 {
143 uint64_t block_a = offset_a >> (2 * s->cluster_bits - REFCOUNT_SHIFT);
144 uint64_t block_b = offset_b >> (2 * s->cluster_bits - REFCOUNT_SHIFT);
145
146 return (block_a == block_b);
147 }
148
149 /*
150 * Loads a refcount block. If it doesn't exist yet, it is allocated first
151 * (including growing the refcount table if needed).
152 *
153 * Returns 0 on success or -errno in error case
154 */
155 static int alloc_refcount_block(BlockDriverState *bs,
156 int64_t cluster_index, uint16_t **refcount_block)
157 {
158 BDRVQcowState *s = bs->opaque;
159 unsigned int refcount_table_index;
160 int ret;
161
162 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC);
163
164 /* Find the refcount block for the given cluster */
165 refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT);
166
167 if (refcount_table_index < s->refcount_table_size) {
168
169 uint64_t refcount_block_offset =
170 s->refcount_table[refcount_table_index];
171
172 /* If it's already there, we're done */
173 if (refcount_block_offset) {
174 return load_refcount_block(bs, refcount_block_offset,
175 (void**) refcount_block);
176 }
177 }
178
179 /*
180 * If we came here, we need to allocate something. Something is at least
181 * a cluster for the new refcount block. It may also include a new refcount
182 * table if the old refcount table is too small.
183 *
184 * Note that allocating clusters here needs some special care:
185 *
186 * - We can't use the normal qcow2_alloc_clusters(), it would try to
187 * increase the refcount and very likely we would end up with an endless
188 * recursion. Instead we must place the refcount blocks in a way that
189 * they can describe them themselves.
190 *
191 * - We need to consider that at this point we are inside update_refcounts
192 * and doing the initial refcount increase. This means that some clusters
193 * have already been allocated by the caller, but their refcount isn't
194 * accurate yet. free_cluster_index tells us where this allocation ends
195 * as long as we don't overwrite it by freeing clusters.
196 *
197 * - alloc_clusters_noref and qcow2_free_clusters may load a different
198 * refcount block into the cache
199 */
200
201 *refcount_block = NULL;
202
203 /* We write to the refcount table, so we might depend on L2 tables */
204 qcow2_cache_flush(bs, s->l2_table_cache);
205
206 /* Allocate the refcount block itself and mark it as used */
207 int64_t new_block = alloc_clusters_noref(bs, s->cluster_size);
208 if (new_block < 0) {
209 return new_block;
210 }
211
212 #ifdef DEBUG_ALLOC2
213 fprintf(stderr, "qcow2: Allocate refcount block %d for %" PRIx64
214 " at %" PRIx64 "\n",
215 refcount_table_index, cluster_index << s->cluster_bits, new_block);
216 #endif
217
218 if (in_same_refcount_block(s, new_block, cluster_index << s->cluster_bits)) {
219 /* Zero the new refcount block before updating it */
220 ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, new_block,
221 (void**) refcount_block);
222 if (ret < 0) {
223 goto fail_block;
224 }
225
226 memset(*refcount_block, 0, s->cluster_size);
227
228 /* The block describes itself, need to update the cache */
229 int block_index = (new_block >> s->cluster_bits) &
230 ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
231 (*refcount_block)[block_index] = cpu_to_be16(1);
232 } else {
233 /* Described somewhere else. This can recurse at most twice before we
234 * arrive at a block that describes itself. */
235 ret = update_refcount(bs, new_block, s->cluster_size, 1);
236 if (ret < 0) {
237 goto fail_block;
238 }
239
240 bdrv_flush(bs->file);
241
242 /* Initialize the new refcount block only after updating its refcount,
243 * update_refcount uses the refcount cache itself */
244 ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, new_block,
245 (void**) refcount_block);
246 if (ret < 0) {
247 goto fail_block;
248 }
249
250 memset(*refcount_block, 0, s->cluster_size);
251 }
252
253 /* Now the new refcount block needs to be written to disk */
254 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE);
255 qcow2_cache_entry_mark_dirty(s->refcount_block_cache, *refcount_block);
256 ret = qcow2_cache_flush(bs, s->refcount_block_cache);
257 if (ret < 0) {
258 goto fail_block;
259 }
260
261 /* If the refcount table is big enough, just hook the block up there */
262 if (refcount_table_index < s->refcount_table_size) {
263 uint64_t data64 = cpu_to_be64(new_block);
264 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_HOOKUP);
265 ret = bdrv_pwrite_sync(bs->file,
266 s->refcount_table_offset + refcount_table_index * sizeof(uint64_t),
267 &data64, sizeof(data64));
268 if (ret < 0) {
269 goto fail_block;
270 }
271
272 s->refcount_table[refcount_table_index] = new_block;
273 return 0;
274 }
275
276 ret = qcow2_cache_put(bs, s->refcount_block_cache, (void**) refcount_block);
277 if (ret < 0) {
278 goto fail_block;
279 }
280
281 /*
282 * If we come here, we need to grow the refcount table. Again, a new
283 * refcount table needs some space and we can't simply allocate to avoid
284 * endless recursion.
285 *
286 * Therefore let's grab new refcount blocks at the end of the image, which
287 * will describe themselves and the new refcount table. This way we can
288 * reference them only in the new table and do the switch to the new
289 * refcount table at once without producing an inconsistent state in
290 * between.
291 */
292 BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_GROW);
293
294 /* Calculate the number of refcount blocks needed so far */
295 uint64_t refcount_block_clusters = 1 << (s->cluster_bits - REFCOUNT_SHIFT);
296 uint64_t blocks_used = (s->free_cluster_index +
297 refcount_block_clusters - 1) / refcount_block_clusters;
298
299 /* And now we need at least one block more for the new metadata */
300 uint64_t table_size = next_refcount_table_size(s, blocks_used + 1);
301 uint64_t last_table_size;
302 uint64_t blocks_clusters;
303 do {
304 uint64_t table_clusters = size_to_clusters(s, table_size);
305 blocks_clusters = 1 +
306 ((table_clusters + refcount_block_clusters - 1)
307 / refcount_block_clusters);
308 uint64_t meta_clusters = table_clusters + blocks_clusters;
309
310 last_table_size = table_size;
311 table_size = next_refcount_table_size(s, blocks_used +
312 ((meta_clusters + refcount_block_clusters - 1)
313 / refcount_block_clusters));
314
315 } while (last_table_size != table_size);
316
317 #ifdef DEBUG_ALLOC2
318 fprintf(stderr, "qcow2: Grow refcount table %" PRId32 " => %" PRId64 "\n",
319 s->refcount_table_size, table_size);
320 #endif
321
322 /* Create the new refcount table and blocks */
323 uint64_t meta_offset = (blocks_used * refcount_block_clusters) *
324 s->cluster_size;
325 uint64_t table_offset = meta_offset + blocks_clusters * s->cluster_size;
326 uint16_t *new_blocks = g_malloc0(blocks_clusters * s->cluster_size);
327 uint64_t *new_table = g_malloc0(table_size * sizeof(uint64_t));
328
329 assert(meta_offset >= (s->free_cluster_index * s->cluster_size));
330
331 /* Fill the new refcount table */
332 memcpy(new_table, s->refcount_table,
333 s->refcount_table_size * sizeof(uint64_t));
334 new_table[refcount_table_index] = new_block;
335
336 int i;
337 for (i = 0; i < blocks_clusters; i++) {
338 new_table[blocks_used + i] = meta_offset + (i * s->cluster_size);
339 }
340
341 /* Fill the refcount blocks */
342 uint64_t table_clusters = size_to_clusters(s, table_size * sizeof(uint64_t));
343 int block = 0;
344 for (i = 0; i < table_clusters + blocks_clusters; i++) {
345 new_blocks[block++] = cpu_to_be16(1);
346 }
347
348 /* Write refcount blocks to disk */
349 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_BLOCKS);
350 ret = bdrv_pwrite_sync(bs->file, meta_offset, new_blocks,
351 blocks_clusters * s->cluster_size);
352 g_free(new_blocks);
353 if (ret < 0) {
354 goto fail_table;
355 }
356
357 /* Write refcount table to disk */
358 for(i = 0; i < table_size; i++) {
359 cpu_to_be64s(&new_table[i]);
360 }
361
362 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_TABLE);
363 ret = bdrv_pwrite_sync(bs->file, table_offset, new_table,
364 table_size * sizeof(uint64_t));
365 if (ret < 0) {
366 goto fail_table;
367 }
368
369 for(i = 0; i < table_size; i++) {
370 cpu_to_be64s(&new_table[i]);
371 }
372
373 /* Hook up the new refcount table in the qcow2 header */
374 uint8_t data[12];
375 cpu_to_be64w((uint64_t*)data, table_offset);
376 cpu_to_be32w((uint32_t*)(data + 8), table_clusters);
377 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_SWITCH_TABLE);
378 ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, refcount_table_offset),
379 data, sizeof(data));
380 if (ret < 0) {
381 goto fail_table;
382 }
383
384 /* And switch it in memory */
385 uint64_t old_table_offset = s->refcount_table_offset;
386 uint64_t old_table_size = s->refcount_table_size;
387
388 g_free(s->refcount_table);
389 s->refcount_table = new_table;
390 s->refcount_table_size = table_size;
391 s->refcount_table_offset = table_offset;
392
393 /* Free old table. Remember, we must not change free_cluster_index */
394 uint64_t old_free_cluster_index = s->free_cluster_index;
395 qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t));
396 s->free_cluster_index = old_free_cluster_index;
397
398 ret = load_refcount_block(bs, new_block, (void**) refcount_block);
399 if (ret < 0) {
400 return ret;
401 }
402
403 return new_block;
404
405 fail_table:
406 g_free(new_table);
407 fail_block:
408 if (*refcount_block != NULL) {
409 qcow2_cache_put(bs, s->refcount_block_cache, (void**) refcount_block);
410 }
411 return ret;
412 }
413
414 /* XXX: cache several refcount block clusters ? */
415 static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
416 int64_t offset, int64_t length, int addend)
417 {
418 BDRVQcowState *s = bs->opaque;
419 int64_t start, last, cluster_offset;
420 uint16_t *refcount_block = NULL;
421 int64_t old_table_index = -1;
422 int ret;
423
424 #ifdef DEBUG_ALLOC2
425 fprintf(stderr, "update_refcount: offset=%" PRId64 " size=%" PRId64 " addend=%d\n",
426 offset, length, addend);
427 #endif
428 if (length < 0) {
429 return -EINVAL;
430 } else if (length == 0) {
431 return 0;
432 }
433
434 if (addend < 0) {
435 qcow2_cache_set_dependency(bs, s->refcount_block_cache,
436 s->l2_table_cache);
437 }
438
439 start = offset & ~(s->cluster_size - 1);
440 last = (offset + length - 1) & ~(s->cluster_size - 1);
441 for(cluster_offset = start; cluster_offset <= last;
442 cluster_offset += s->cluster_size)
443 {
444 int block_index, refcount;
445 int64_t cluster_index = cluster_offset >> s->cluster_bits;
446 int64_t table_index =
447 cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT);
448
449 /* Load the refcount block and allocate it if needed */
450 if (table_index != old_table_index) {
451 if (refcount_block) {
452 ret = qcow2_cache_put(bs, s->refcount_block_cache,
453 (void**) &refcount_block);
454 if (ret < 0) {
455 goto fail;
456 }
457 }
458
459 ret = alloc_refcount_block(bs, cluster_index, &refcount_block);
460 if (ret < 0) {
461 goto fail;
462 }
463 }
464 old_table_index = table_index;
465
466 qcow2_cache_entry_mark_dirty(s->refcount_block_cache, refcount_block);
467
468 /* we can update the count and save it */
469 block_index = cluster_index &
470 ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
471
472 refcount = be16_to_cpu(refcount_block[block_index]);
473 refcount += addend;
474 if (refcount < 0 || refcount > 0xffff) {
475 ret = -EINVAL;
476 goto fail;
477 }
478 if (refcount == 0 && cluster_index < s->free_cluster_index) {
479 s->free_cluster_index = cluster_index;
480 }
481 refcount_block[block_index] = cpu_to_be16(refcount);
482 }
483
484 ret = 0;
485 fail:
486 /* Write last changed block to disk */
487 if (refcount_block) {
488 int wret;
489 wret = qcow2_cache_put(bs, s->refcount_block_cache,
490 (void**) &refcount_block);
491 if (wret < 0) {
492 return ret < 0 ? ret : wret;
493 }
494 }
495
496 /*
497 * Try do undo any updates if an error is returned (This may succeed in
498 * some cases like ENOSPC for allocating a new refcount block)
499 */
500 if (ret < 0) {
501 int dummy;
502 dummy = update_refcount(bs, offset, cluster_offset - offset, -addend);
503 (void)dummy;
504 }
505
506 return ret;
507 }
508
509 /*
510 * Increases or decreases the refcount of a given cluster by one.
511 * addend must be 1 or -1.
512 *
513 * If the return value is non-negative, it is the new refcount of the cluster.
514 * If it is negative, it is -errno and indicates an error.
515 */
516 static int update_cluster_refcount(BlockDriverState *bs,
517 int64_t cluster_index,
518 int addend)
519 {
520 BDRVQcowState *s = bs->opaque;
521 int ret;
522
523 ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend);
524 if (ret < 0) {
525 return ret;
526 }
527
528 bdrv_flush(bs->file);
529
530 return get_refcount(bs, cluster_index);
531 }
532
533
534
535 /*********************************************************/
536 /* cluster allocation functions */
537
538
539
540 /* return < 0 if error */
541 static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size)
542 {
543 BDRVQcowState *s = bs->opaque;
544 int i, nb_clusters, refcount;
545
546 nb_clusters = size_to_clusters(s, size);
547 retry:
548 for(i = 0; i < nb_clusters; i++) {
549 int64_t next_cluster_index = s->free_cluster_index++;
550 refcount = get_refcount(bs, next_cluster_index);
551
552 if (refcount < 0) {
553 return refcount;
554 } else if (refcount != 0) {
555 goto retry;
556 }
557 }
558 #ifdef DEBUG_ALLOC2
559 fprintf(stderr, "alloc_clusters: size=%" PRId64 " -> %" PRId64 "\n",
560 size,
561 (s->free_cluster_index - nb_clusters) << s->cluster_bits);
562 #endif
563 return (s->free_cluster_index - nb_clusters) << s->cluster_bits;
564 }
565
566 int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size)
567 {
568 int64_t offset;
569 int ret;
570
571 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC);
572 offset = alloc_clusters_noref(bs, size);
573 if (offset < 0) {
574 return offset;
575 }
576
577 ret = update_refcount(bs, offset, size, 1);
578 if (ret < 0) {
579 return ret;
580 }
581
582 return offset;
583 }
584
585 /* only used to allocate compressed sectors. We try to allocate
586 contiguous sectors. size must be <= cluster_size */
587 int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
588 {
589 BDRVQcowState *s = bs->opaque;
590 int64_t offset, cluster_offset;
591 int free_in_cluster;
592
593 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_BYTES);
594 assert(size > 0 && size <= s->cluster_size);
595 if (s->free_byte_offset == 0) {
596 s->free_byte_offset = qcow2_alloc_clusters(bs, s->cluster_size);
597 if (s->free_byte_offset < 0) {
598 return s->free_byte_offset;
599 }
600 }
601 redo:
602 free_in_cluster = s->cluster_size -
603 (s->free_byte_offset & (s->cluster_size - 1));
604 if (size <= free_in_cluster) {
605 /* enough space in current cluster */
606 offset = s->free_byte_offset;
607 s->free_byte_offset += size;
608 free_in_cluster -= size;
609 if (free_in_cluster == 0)
610 s->free_byte_offset = 0;
611 if ((offset & (s->cluster_size - 1)) != 0)
612 update_cluster_refcount(bs, offset >> s->cluster_bits, 1);
613 } else {
614 offset = qcow2_alloc_clusters(bs, s->cluster_size);
615 if (offset < 0) {
616 return offset;
617 }
618 cluster_offset = s->free_byte_offset & ~(s->cluster_size - 1);
619 if ((cluster_offset + s->cluster_size) == offset) {
620 /* we are lucky: contiguous data */
621 offset = s->free_byte_offset;
622 update_cluster_refcount(bs, offset >> s->cluster_bits, 1);
623 s->free_byte_offset += size;
624 } else {
625 s->free_byte_offset = offset;
626 goto redo;
627 }
628 }
629
630 bdrv_flush(bs->file);
631 return offset;
632 }
633
634 void qcow2_free_clusters(BlockDriverState *bs,
635 int64_t offset, int64_t size)
636 {
637 int ret;
638
639 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_FREE);
640 ret = update_refcount(bs, offset, size, -1);
641 if (ret < 0) {
642 fprintf(stderr, "qcow2_free_clusters failed: %s\n", strerror(-ret));
643 /* TODO Remember the clusters to free them later and avoid leaking */
644 }
645 }
646
647 /*
648 * free_any_clusters
649 *
650 * free clusters according to its type: compressed or not
651 *
652 */
653
654 void qcow2_free_any_clusters(BlockDriverState *bs,
655 uint64_t cluster_offset, int nb_clusters)
656 {
657 BDRVQcowState *s = bs->opaque;
658
659 /* free the cluster */
660
661 if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
662 int nb_csectors;
663 nb_csectors = ((cluster_offset >> s->csize_shift) &
664 s->csize_mask) + 1;
665 qcow2_free_clusters(bs,
666 (cluster_offset & s->cluster_offset_mask) & ~511,
667 nb_csectors * 512);
668 return;
669 }
670
671 qcow2_free_clusters(bs, cluster_offset, nb_clusters << s->cluster_bits);
672
673 return;
674 }
675
676
677
678 /*********************************************************/
679 /* snapshots and image creation */
680
681
682
683 /* update the refcounts of snapshots and the copied flag */
684 int qcow2_update_snapshot_refcount(BlockDriverState *bs,
685 int64_t l1_table_offset, int l1_size, int addend)
686 {
687 BDRVQcowState *s = bs->opaque;
688 uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2, l1_allocated;
689 int64_t old_offset, old_l2_offset;
690 int i, j, l1_modified = 0, nb_csectors, refcount;
691 int ret;
692 bool old_l2_writethrough, old_refcount_writethrough;
693
694 /* Switch caches to writeback mode during update */
695 old_l2_writethrough =
696 qcow2_cache_set_writethrough(bs, s->l2_table_cache, false);
697 old_refcount_writethrough =
698 qcow2_cache_set_writethrough(bs, s->refcount_block_cache, false);
699
700 l2_table = NULL;
701 l1_table = NULL;
702 l1_size2 = l1_size * sizeof(uint64_t);
703
704 /* WARNING: qcow2_snapshot_goto relies on this function not using the
705 * l1_table_offset when it is the current s->l1_table_offset! Be careful
706 * when changing this! */
707 if (l1_table_offset != s->l1_table_offset) {
708 if (l1_size2 != 0) {
709 l1_table = g_malloc0(align_offset(l1_size2, 512));
710 } else {
711 l1_table = NULL;
712 }
713 l1_allocated = 1;
714 if (bdrv_pread(bs->file, l1_table_offset,
715 l1_table, l1_size2) != l1_size2)
716 {
717 ret = -EIO;
718 goto fail;
719 }
720
721 for(i = 0;i < l1_size; i++)
722 be64_to_cpus(&l1_table[i]);
723 } else {
724 assert(l1_size == s->l1_size);
725 l1_table = s->l1_table;
726 l1_allocated = 0;
727 }
728
729 for(i = 0; i < l1_size; i++) {
730 l2_offset = l1_table[i];
731 if (l2_offset) {
732 old_l2_offset = l2_offset;
733 l2_offset &= ~QCOW_OFLAG_COPIED;
734
735 ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset,
736 (void**) &l2_table);
737 if (ret < 0) {
738 goto fail;
739 }
740
741 for(j = 0; j < s->l2_size; j++) {
742 offset = be64_to_cpu(l2_table[j]);
743 if (offset != 0) {
744 old_offset = offset;
745 offset &= ~QCOW_OFLAG_COPIED;
746 if (offset & QCOW_OFLAG_COMPRESSED) {
747 nb_csectors = ((offset >> s->csize_shift) &
748 s->csize_mask) + 1;
749 if (addend != 0) {
750 int ret;
751 ret = update_refcount(bs,
752 (offset & s->cluster_offset_mask) & ~511,
753 nb_csectors * 512, addend);
754 if (ret < 0) {
755 goto fail;
756 }
757
758 /* TODO Flushing once for the whole function should
759 * be enough */
760 bdrv_flush(bs->file);
761 }
762 /* compressed clusters are never modified */
763 refcount = 2;
764 } else {
765 if (addend != 0) {
766 refcount = update_cluster_refcount(bs, offset >> s->cluster_bits, addend);
767 } else {
768 refcount = get_refcount(bs, offset >> s->cluster_bits);
769 }
770
771 if (refcount < 0) {
772 ret = -EIO;
773 goto fail;
774 }
775 }
776
777 if (refcount == 1) {
778 offset |= QCOW_OFLAG_COPIED;
779 }
780 if (offset != old_offset) {
781 if (addend > 0) {
782 qcow2_cache_set_dependency(bs, s->l2_table_cache,
783 s->refcount_block_cache);
784 }
785 l2_table[j] = cpu_to_be64(offset);
786 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
787 }
788 }
789 }
790
791 ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
792 if (ret < 0) {
793 goto fail;
794 }
795
796
797 if (addend != 0) {
798 refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend);
799 } else {
800 refcount = get_refcount(bs, l2_offset >> s->cluster_bits);
801 }
802 if (refcount < 0) {
803 ret = -EIO;
804 goto fail;
805 } else if (refcount == 1) {
806 l2_offset |= QCOW_OFLAG_COPIED;
807 }
808 if (l2_offset != old_l2_offset) {
809 l1_table[i] = l2_offset;
810 l1_modified = 1;
811 }
812 }
813 }
814
815 ret = 0;
816 fail:
817 if (l2_table) {
818 qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
819 }
820
821 /* Enable writethrough cache mode again */
822 qcow2_cache_set_writethrough(bs, s->l2_table_cache, old_l2_writethrough);
823 qcow2_cache_set_writethrough(bs, s->refcount_block_cache,
824 old_refcount_writethrough);
825
826 /* Update L1 only if it isn't deleted anyway (addend = -1) */
827 if (addend >= 0 && l1_modified) {
828 for(i = 0; i < l1_size; i++)
829 cpu_to_be64s(&l1_table[i]);
830 if (bdrv_pwrite_sync(bs->file, l1_table_offset, l1_table,
831 l1_size2) < 0)
832 goto fail;
833 for(i = 0; i < l1_size; i++)
834 be64_to_cpus(&l1_table[i]);
835 }
836 if (l1_allocated)
837 g_free(l1_table);
838 return ret;
839 }
840
841
842
843
844 /*********************************************************/
845 /* refcount checking functions */
846
847
848
849 /*
850 * Increases the refcount for a range of clusters in a given refcount table.
851 * This is used to construct a temporary refcount table out of L1 and L2 tables
852 * which can be compared the the refcount table saved in the image.
853 *
854 * Modifies the number of errors in res.
855 */
856 static void inc_refcounts(BlockDriverState *bs,
857 BdrvCheckResult *res,
858 uint16_t *refcount_table,
859 int refcount_table_size,
860 int64_t offset, int64_t size)
861 {
862 BDRVQcowState *s = bs->opaque;
863 int64_t start, last, cluster_offset;
864 int k;
865
866 if (size <= 0)
867 return;
868
869 start = offset & ~(s->cluster_size - 1);
870 last = (offset + size - 1) & ~(s->cluster_size - 1);
871 for(cluster_offset = start; cluster_offset <= last;
872 cluster_offset += s->cluster_size) {
873 k = cluster_offset >> s->cluster_bits;
874 if (k < 0) {
875 fprintf(stderr, "ERROR: invalid cluster offset=0x%" PRIx64 "\n",
876 cluster_offset);
877 res->corruptions++;
878 } else if (k >= refcount_table_size) {
879 fprintf(stderr, "Warning: cluster offset=0x%" PRIx64 " is after "
880 "the end of the image file, can't properly check refcounts.\n",
881 cluster_offset);
882 res->check_errors++;
883 } else {
884 if (++refcount_table[k] == 0) {
885 fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64
886 "\n", cluster_offset);
887 res->corruptions++;
888 }
889 }
890 }
891 }
892
893 /*
894 * Increases the refcount in the given refcount table for the all clusters
895 * referenced in the L2 table. While doing so, performs some checks on L2
896 * entries.
897 *
898 * Returns the number of errors found by the checks or -errno if an internal
899 * error occurred.
900 */
901 static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res,
902 uint16_t *refcount_table, int refcount_table_size, int64_t l2_offset,
903 int check_copied)
904 {
905 BDRVQcowState *s = bs->opaque;
906 uint64_t *l2_table, offset;
907 int i, l2_size, nb_csectors, refcount;
908
909 /* Read L2 table from disk */
910 l2_size = s->l2_size * sizeof(uint64_t);
911 l2_table = g_malloc(l2_size);
912
913 if (bdrv_pread(bs->file, l2_offset, l2_table, l2_size) != l2_size)
914 goto fail;
915
916 /* Do the actual checks */
917 for(i = 0; i < s->l2_size; i++) {
918 offset = be64_to_cpu(l2_table[i]);
919 if (offset != 0) {
920 if (offset & QCOW_OFLAG_COMPRESSED) {
921 /* Compressed clusters don't have QCOW_OFLAG_COPIED */
922 if (offset & QCOW_OFLAG_COPIED) {
923 fprintf(stderr, "ERROR: cluster %" PRId64 ": "
924 "copied flag must never be set for compressed "
925 "clusters\n", offset >> s->cluster_bits);
926 offset &= ~QCOW_OFLAG_COPIED;
927 res->corruptions++;
928 }
929
930 /* Mark cluster as used */
931 nb_csectors = ((offset >> s->csize_shift) &
932 s->csize_mask) + 1;
933 offset &= s->cluster_offset_mask;
934 inc_refcounts(bs, res, refcount_table, refcount_table_size,
935 offset & ~511, nb_csectors * 512);
936 } else {
937 /* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
938 if (check_copied) {
939 uint64_t entry = offset;
940 offset &= ~QCOW_OFLAG_COPIED;
941 refcount = get_refcount(bs, offset >> s->cluster_bits);
942 if (refcount < 0) {
943 fprintf(stderr, "Can't get refcount for offset %"
944 PRIx64 ": %s\n", entry, strerror(-refcount));
945 goto fail;
946 }
947 if ((refcount == 1) != ((entry & QCOW_OFLAG_COPIED) != 0)) {
948 fprintf(stderr, "ERROR OFLAG_COPIED: offset=%"
949 PRIx64 " refcount=%d\n", entry, refcount);
950 res->corruptions++;
951 }
952 }
953
954 /* Mark cluster as used */
955 offset &= ~QCOW_OFLAG_COPIED;
956 inc_refcounts(bs, res, refcount_table,refcount_table_size,
957 offset, s->cluster_size);
958
959 /* Correct offsets are cluster aligned */
960 if (offset & (s->cluster_size - 1)) {
961 fprintf(stderr, "ERROR offset=%" PRIx64 ": Cluster is not "
962 "properly aligned; L2 entry corrupted.\n", offset);
963 res->corruptions++;
964 }
965 }
966 }
967 }
968
969 g_free(l2_table);
970 return 0;
971
972 fail:
973 fprintf(stderr, "ERROR: I/O error in check_refcounts_l2\n");
974 g_free(l2_table);
975 return -EIO;
976 }
977
978 /*
979 * Increases the refcount for the L1 table, its L2 tables and all referenced
980 * clusters in the given refcount table. While doing so, performs some checks
981 * on L1 and L2 entries.
982 *
983 * Returns the number of errors found by the checks or -errno if an internal
984 * error occurred.
985 */
986 static int check_refcounts_l1(BlockDriverState *bs,
987 BdrvCheckResult *res,
988 uint16_t *refcount_table,
989 int refcount_table_size,
990 int64_t l1_table_offset, int l1_size,
991 int check_copied)
992 {
993 BDRVQcowState *s = bs->opaque;
994 uint64_t *l1_table, l2_offset, l1_size2;
995 int i, refcount, ret;
996
997 l1_size2 = l1_size * sizeof(uint64_t);
998
999 /* Mark L1 table as used */
1000 inc_refcounts(bs, res, refcount_table, refcount_table_size,
1001 l1_table_offset, l1_size2);
1002
1003 /* Read L1 table entries from disk */
1004 if (l1_size2 == 0) {
1005 l1_table = NULL;
1006 } else {
1007 l1_table = g_malloc(l1_size2);
1008 if (bdrv_pread(bs->file, l1_table_offset,
1009 l1_table, l1_size2) != l1_size2)
1010 goto fail;
1011 for(i = 0;i < l1_size; i++)
1012 be64_to_cpus(&l1_table[i]);
1013 }
1014
1015 /* Do the actual checks */
1016 for(i = 0; i < l1_size; i++) {
1017 l2_offset = l1_table[i];
1018 if (l2_offset) {
1019 /* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
1020 if (check_copied) {
1021 refcount = get_refcount(bs, (l2_offset & ~QCOW_OFLAG_COPIED)
1022 >> s->cluster_bits);
1023 if (refcount < 0) {
1024 fprintf(stderr, "Can't get refcount for l2_offset %"
1025 PRIx64 ": %s\n", l2_offset, strerror(-refcount));
1026 goto fail;
1027 }
1028 if ((refcount == 1) != ((l2_offset & QCOW_OFLAG_COPIED) != 0)) {
1029 fprintf(stderr, "ERROR OFLAG_COPIED: l2_offset=%" PRIx64
1030 " refcount=%d\n", l2_offset, refcount);
1031 res->corruptions++;
1032 }
1033 }
1034
1035 /* Mark L2 table as used */
1036 l2_offset &= ~QCOW_OFLAG_COPIED;
1037 inc_refcounts(bs, res, refcount_table, refcount_table_size,
1038 l2_offset, s->cluster_size);
1039
1040 /* L2 tables are cluster aligned */
1041 if (l2_offset & (s->cluster_size - 1)) {
1042 fprintf(stderr, "ERROR l2_offset=%" PRIx64 ": Table is not "
1043 "cluster aligned; L1 entry corrupted\n", l2_offset);
1044 res->corruptions++;
1045 }
1046
1047 /* Process and check L2 entries */
1048 ret = check_refcounts_l2(bs, res, refcount_table,
1049 refcount_table_size, l2_offset, check_copied);
1050 if (ret < 0) {
1051 goto fail;
1052 }
1053 }
1054 }
1055 g_free(l1_table);
1056 return 0;
1057
1058 fail:
1059 fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n");
1060 res->check_errors++;
1061 g_free(l1_table);
1062 return -EIO;
1063 }
1064
1065 /*
1066 * Checks an image for refcount consistency.
1067 *
1068 * Returns 0 if no errors are found, the number of errors in case the image is
1069 * detected as corrupted, and -errno when an internal error occurred.
1070 */
1071 int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res)
1072 {
1073 BDRVQcowState *s = bs->opaque;
1074 int64_t size;
1075 int nb_clusters, refcount1, refcount2, i;
1076 QCowSnapshot *sn;
1077 uint16_t *refcount_table;
1078 int ret;
1079
1080 size = bdrv_getlength(bs->file);
1081 nb_clusters = size_to_clusters(s, size);
1082 refcount_table = g_malloc0(nb_clusters * sizeof(uint16_t));
1083
1084 /* header */
1085 inc_refcounts(bs, res, refcount_table, nb_clusters,
1086 0, s->cluster_size);
1087
1088 /* current L1 table */
1089 ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters,
1090 s->l1_table_offset, s->l1_size, 1);
1091 if (ret < 0) {
1092 goto fail;
1093 }
1094
1095 /* snapshots */
1096 for(i = 0; i < s->nb_snapshots; i++) {
1097 sn = s->snapshots + i;
1098 ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters,
1099 sn->l1_table_offset, sn->l1_size, 0);
1100 if (ret < 0) {
1101 goto fail;
1102 }
1103 }
1104 inc_refcounts(bs, res, refcount_table, nb_clusters,
1105 s->snapshots_offset, s->snapshots_size);
1106
1107 /* refcount data */
1108 inc_refcounts(bs, res, refcount_table, nb_clusters,
1109 s->refcount_table_offset,
1110 s->refcount_table_size * sizeof(uint64_t));
1111
1112 for(i = 0; i < s->refcount_table_size; i++) {
1113 uint64_t offset, cluster;
1114 offset = s->refcount_table[i];
1115 cluster = offset >> s->cluster_bits;
1116
1117 /* Refcount blocks are cluster aligned */
1118 if (offset & (s->cluster_size - 1)) {
1119 fprintf(stderr, "ERROR refcount block %d is not "
1120 "cluster aligned; refcount table entry corrupted\n", i);
1121 res->corruptions++;
1122 continue;
1123 }
1124
1125 if (cluster >= nb_clusters) {
1126 fprintf(stderr, "ERROR refcount block %d is outside image\n", i);
1127 res->corruptions++;
1128 continue;
1129 }
1130
1131 if (offset != 0) {
1132 inc_refcounts(bs, res, refcount_table, nb_clusters,
1133 offset, s->cluster_size);
1134 if (refcount_table[cluster] != 1) {
1135 fprintf(stderr, "ERROR refcount block %d refcount=%d\n",
1136 i, refcount_table[cluster]);
1137 res->corruptions++;
1138 }
1139 }
1140 }
1141
1142 /* compare ref counts */
1143 for(i = 0; i < nb_clusters; i++) {
1144 refcount1 = get_refcount(bs, i);
1145 if (refcount1 < 0) {
1146 fprintf(stderr, "Can't get refcount for cluster %d: %s\n",
1147 i, strerror(-refcount1));
1148 res->check_errors++;
1149 continue;
1150 }
1151
1152 refcount2 = refcount_table[i];
1153 if (refcount1 != refcount2) {
1154 fprintf(stderr, "%s cluster %d refcount=%d reference=%d\n",
1155 refcount1 < refcount2 ? "ERROR" : "Leaked",
1156 i, refcount1, refcount2);
1157 if (refcount1 < refcount2) {
1158 res->corruptions++;
1159 } else {
1160 res->leaks++;
1161 }
1162 }
1163 }
1164
1165 ret = 0;
1166
1167 fail:
1168 g_free(refcount_table);
1169
1170 return ret;
1171 }
1172