2 * Block driver for the QCOW version 2 format
4 * Copyright (c) 2004-2006 Fabrice Bellard
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:
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
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
25 #include "qemu/osdep.h"
26 #include "qapi/error.h"
27 #include "qemu-common.h"
28 #include "block/block_int.h"
29 #include "block/qcow2.h"
30 #include "qemu/range.h"
31 #include "qemu/bswap.h"
32 #include "qemu/cutils.h"
34 static int64_t alloc_clusters_noref(BlockDriverState
*bs
, uint64_t size
);
35 static int QEMU_WARN_UNUSED_RESULT
update_refcount(BlockDriverState
*bs
,
36 int64_t offset
, int64_t length
, uint64_t addend
,
37 bool decrease
, enum qcow2_discard_type type
);
39 static uint64_t get_refcount_ro0(const void *refcount_array
, uint64_t index
);
40 static uint64_t get_refcount_ro1(const void *refcount_array
, uint64_t index
);
41 static uint64_t get_refcount_ro2(const void *refcount_array
, uint64_t index
);
42 static uint64_t get_refcount_ro3(const void *refcount_array
, uint64_t index
);
43 static uint64_t get_refcount_ro4(const void *refcount_array
, uint64_t index
);
44 static uint64_t get_refcount_ro5(const void *refcount_array
, uint64_t index
);
45 static uint64_t get_refcount_ro6(const void *refcount_array
, uint64_t index
);
47 static void set_refcount_ro0(void *refcount_array
, uint64_t index
,
49 static void set_refcount_ro1(void *refcount_array
, uint64_t index
,
51 static void set_refcount_ro2(void *refcount_array
, uint64_t index
,
53 static void set_refcount_ro3(void *refcount_array
, uint64_t index
,
55 static void set_refcount_ro4(void *refcount_array
, uint64_t index
,
57 static void set_refcount_ro5(void *refcount_array
, uint64_t index
,
59 static void set_refcount_ro6(void *refcount_array
, uint64_t index
,
63 static Qcow2GetRefcountFunc
*const get_refcount_funcs
[] = {
73 static Qcow2SetRefcountFunc
*const set_refcount_funcs
[] = {
84 /*********************************************************/
85 /* refcount handling */
87 static void update_max_refcount_table_index(BDRVQcow2State
*s
)
89 unsigned i
= s
->refcount_table_size
- 1;
90 while (i
> 0 && (s
->refcount_table
[i
] & REFT_OFFSET_MASK
) == 0) {
93 /* Set s->max_refcount_table_index to the index of the last used entry */
94 s
->max_refcount_table_index
= i
;
97 int qcow2_refcount_init(BlockDriverState
*bs
)
99 BDRVQcow2State
*s
= bs
->opaque
;
100 unsigned int refcount_table_size2
, i
;
103 assert(s
->refcount_order
>= 0 && s
->refcount_order
<= 6);
105 s
->get_refcount
= get_refcount_funcs
[s
->refcount_order
];
106 s
->set_refcount
= set_refcount_funcs
[s
->refcount_order
];
108 assert(s
->refcount_table_size
<= INT_MAX
/ sizeof(uint64_t));
109 refcount_table_size2
= s
->refcount_table_size
* sizeof(uint64_t);
110 s
->refcount_table
= g_try_malloc(refcount_table_size2
);
112 if (s
->refcount_table_size
> 0) {
113 if (s
->refcount_table
== NULL
) {
117 BLKDBG_EVENT(bs
->file
, BLKDBG_REFTABLE_LOAD
);
118 ret
= bdrv_pread(bs
->file
, s
->refcount_table_offset
,
119 s
->refcount_table
, refcount_table_size2
);
123 for(i
= 0; i
< s
->refcount_table_size
; i
++)
124 be64_to_cpus(&s
->refcount_table
[i
]);
125 update_max_refcount_table_index(s
);
132 void qcow2_refcount_close(BlockDriverState
*bs
)
134 BDRVQcow2State
*s
= bs
->opaque
;
135 g_free(s
->refcount_table
);
139 static uint64_t get_refcount_ro0(const void *refcount_array
, uint64_t index
)
141 return (((const uint8_t *)refcount_array
)[index
/ 8] >> (index
% 8)) & 0x1;
144 static void set_refcount_ro0(void *refcount_array
, uint64_t index
,
147 assert(!(value
>> 1));
148 ((uint8_t *)refcount_array
)[index
/ 8] &= ~(0x1 << (index
% 8));
149 ((uint8_t *)refcount_array
)[index
/ 8] |= value
<< (index
% 8);
152 static uint64_t get_refcount_ro1(const void *refcount_array
, uint64_t index
)
154 return (((const uint8_t *)refcount_array
)[index
/ 4] >> (2 * (index
% 4)))
158 static void set_refcount_ro1(void *refcount_array
, uint64_t index
,
161 assert(!(value
>> 2));
162 ((uint8_t *)refcount_array
)[index
/ 4] &= ~(0x3 << (2 * (index
% 4)));
163 ((uint8_t *)refcount_array
)[index
/ 4] |= value
<< (2 * (index
% 4));
166 static uint64_t get_refcount_ro2(const void *refcount_array
, uint64_t index
)
168 return (((const uint8_t *)refcount_array
)[index
/ 2] >> (4 * (index
% 2)))
172 static void set_refcount_ro2(void *refcount_array
, uint64_t index
,
175 assert(!(value
>> 4));
176 ((uint8_t *)refcount_array
)[index
/ 2] &= ~(0xf << (4 * (index
% 2)));
177 ((uint8_t *)refcount_array
)[index
/ 2] |= value
<< (4 * (index
% 2));
180 static uint64_t get_refcount_ro3(const void *refcount_array
, uint64_t index
)
182 return ((const uint8_t *)refcount_array
)[index
];
185 static void set_refcount_ro3(void *refcount_array
, uint64_t index
,
188 assert(!(value
>> 8));
189 ((uint8_t *)refcount_array
)[index
] = value
;
192 static uint64_t get_refcount_ro4(const void *refcount_array
, uint64_t index
)
194 return be16_to_cpu(((const uint16_t *)refcount_array
)[index
]);
197 static void set_refcount_ro4(void *refcount_array
, uint64_t index
,
200 assert(!(value
>> 16));
201 ((uint16_t *)refcount_array
)[index
] = cpu_to_be16(value
);
204 static uint64_t get_refcount_ro5(const void *refcount_array
, uint64_t index
)
206 return be32_to_cpu(((const uint32_t *)refcount_array
)[index
]);
209 static void set_refcount_ro5(void *refcount_array
, uint64_t index
,
212 assert(!(value
>> 32));
213 ((uint32_t *)refcount_array
)[index
] = cpu_to_be32(value
);
216 static uint64_t get_refcount_ro6(const void *refcount_array
, uint64_t index
)
218 return be64_to_cpu(((const uint64_t *)refcount_array
)[index
]);
221 static void set_refcount_ro6(void *refcount_array
, uint64_t index
,
224 ((uint64_t *)refcount_array
)[index
] = cpu_to_be64(value
);
228 static int load_refcount_block(BlockDriverState
*bs
,
229 int64_t refcount_block_offset
,
230 void **refcount_block
)
232 BDRVQcow2State
*s
= bs
->opaque
;
234 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_LOAD
);
235 return qcow2_cache_get(bs
, s
->refcount_block_cache
, refcount_block_offset
,
240 * Retrieves the refcount of the cluster given by its index and stores it in
241 * *refcount. Returns 0 on success and -errno on failure.
243 int qcow2_get_refcount(BlockDriverState
*bs
, int64_t cluster_index
,
246 BDRVQcow2State
*s
= bs
->opaque
;
247 uint64_t refcount_table_index
, block_index
;
248 int64_t refcount_block_offset
;
250 void *refcount_block
;
252 refcount_table_index
= cluster_index
>> s
->refcount_block_bits
;
253 if (refcount_table_index
>= s
->refcount_table_size
) {
257 refcount_block_offset
=
258 s
->refcount_table
[refcount_table_index
] & REFT_OFFSET_MASK
;
259 if (!refcount_block_offset
) {
264 if (offset_into_cluster(s
, refcount_block_offset
)) {
265 qcow2_signal_corruption(bs
, true, -1, -1, "Refblock offset %#" PRIx64
266 " unaligned (reftable index: %#" PRIx64
")",
267 refcount_block_offset
, refcount_table_index
);
271 ret
= qcow2_cache_get(bs
, s
->refcount_block_cache
, refcount_block_offset
,
277 block_index
= cluster_index
& (s
->refcount_block_size
- 1);
278 *refcount
= s
->get_refcount(refcount_block
, block_index
);
280 qcow2_cache_put(s
->refcount_block_cache
, &refcount_block
);
285 /* Checks if two offsets are described by the same refcount block */
286 static int in_same_refcount_block(BDRVQcow2State
*s
, uint64_t offset_a
,
289 uint64_t block_a
= offset_a
>> (s
->cluster_bits
+ s
->refcount_block_bits
);
290 uint64_t block_b
= offset_b
>> (s
->cluster_bits
+ s
->refcount_block_bits
);
292 return (block_a
== block_b
);
296 * Loads a refcount block. If it doesn't exist yet, it is allocated first
297 * (including growing the refcount table if needed).
299 * Returns 0 on success or -errno in error case
301 static int alloc_refcount_block(BlockDriverState
*bs
,
302 int64_t cluster_index
, void **refcount_block
)
304 BDRVQcow2State
*s
= bs
->opaque
;
305 unsigned int refcount_table_index
;
308 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_ALLOC
);
310 /* Find the refcount block for the given cluster */
311 refcount_table_index
= cluster_index
>> s
->refcount_block_bits
;
313 if (refcount_table_index
< s
->refcount_table_size
) {
315 uint64_t refcount_block_offset
=
316 s
->refcount_table
[refcount_table_index
] & REFT_OFFSET_MASK
;
318 /* If it's already there, we're done */
319 if (refcount_block_offset
) {
320 if (offset_into_cluster(s
, refcount_block_offset
)) {
321 qcow2_signal_corruption(bs
, true, -1, -1, "Refblock offset %#"
322 PRIx64
" unaligned (reftable index: "
323 "%#x)", refcount_block_offset
,
324 refcount_table_index
);
328 return load_refcount_block(bs
, refcount_block_offset
,
334 * If we came here, we need to allocate something. Something is at least
335 * a cluster for the new refcount block. It may also include a new refcount
336 * table if the old refcount table is too small.
338 * Note that allocating clusters here needs some special care:
340 * - We can't use the normal qcow2_alloc_clusters(), it would try to
341 * increase the refcount and very likely we would end up with an endless
342 * recursion. Instead we must place the refcount blocks in a way that
343 * they can describe them themselves.
345 * - We need to consider that at this point we are inside update_refcounts
346 * and potentially doing an initial refcount increase. This means that
347 * some clusters have already been allocated by the caller, but their
348 * refcount isn't accurate yet. If we allocate clusters for metadata, we
349 * need to return -EAGAIN to signal the caller that it needs to restart
350 * the search for free clusters.
352 * - alloc_clusters_noref and qcow2_free_clusters may load a different
353 * refcount block into the cache
356 *refcount_block
= NULL
;
358 /* We write to the refcount table, so we might depend on L2 tables */
359 ret
= qcow2_cache_flush(bs
, s
->l2_table_cache
);
364 /* Allocate the refcount block itself and mark it as used */
365 int64_t new_block
= alloc_clusters_noref(bs
, s
->cluster_size
);
370 /* If we're allocating the block at offset 0 then something is wrong */
371 if (new_block
== 0) {
372 qcow2_signal_corruption(bs
, true, -1, -1, "Preventing invalid "
373 "allocation of refcount block at offset 0");
378 fprintf(stderr
, "qcow2: Allocate refcount block %d for %" PRIx64
380 refcount_table_index
, cluster_index
<< s
->cluster_bits
, new_block
);
383 if (in_same_refcount_block(s
, new_block
, cluster_index
<< s
->cluster_bits
)) {
384 /* Zero the new refcount block before updating it */
385 ret
= qcow2_cache_get_empty(bs
, s
->refcount_block_cache
, new_block
,
391 memset(*refcount_block
, 0, s
->cluster_size
);
393 /* The block describes itself, need to update the cache */
394 int block_index
= (new_block
>> s
->cluster_bits
) &
395 (s
->refcount_block_size
- 1);
396 s
->set_refcount(*refcount_block
, block_index
, 1);
398 /* Described somewhere else. This can recurse at most twice before we
399 * arrive at a block that describes itself. */
400 ret
= update_refcount(bs
, new_block
, s
->cluster_size
, 1, false,
401 QCOW2_DISCARD_NEVER
);
406 ret
= qcow2_cache_flush(bs
, s
->refcount_block_cache
);
411 /* Initialize the new refcount block only after updating its refcount,
412 * update_refcount uses the refcount cache itself */
413 ret
= qcow2_cache_get_empty(bs
, s
->refcount_block_cache
, new_block
,
419 memset(*refcount_block
, 0, s
->cluster_size
);
422 /* Now the new refcount block needs to be written to disk */
423 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_ALLOC_WRITE
);
424 qcow2_cache_entry_mark_dirty(s
->refcount_block_cache
, *refcount_block
);
425 ret
= qcow2_cache_flush(bs
, s
->refcount_block_cache
);
430 /* If the refcount table is big enough, just hook the block up there */
431 if (refcount_table_index
< s
->refcount_table_size
) {
432 uint64_t data64
= cpu_to_be64(new_block
);
433 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_ALLOC_HOOKUP
);
434 ret
= bdrv_pwrite_sync(bs
->file
,
435 s
->refcount_table_offset
+ refcount_table_index
* sizeof(uint64_t),
436 &data64
, sizeof(data64
));
441 s
->refcount_table
[refcount_table_index
] = new_block
;
442 /* If there's a hole in s->refcount_table then it can happen
443 * that refcount_table_index < s->max_refcount_table_index */
444 s
->max_refcount_table_index
=
445 MAX(s
->max_refcount_table_index
, refcount_table_index
);
447 /* The new refcount block may be where the caller intended to put its
448 * data, so let it restart the search. */
452 qcow2_cache_put(s
->refcount_block_cache
, refcount_block
);
455 * If we come here, we need to grow the refcount table. Again, a new
456 * refcount table needs some space and we can't simply allocate to avoid
459 * Therefore let's grab new refcount blocks at the end of the image, which
460 * will describe themselves and the new refcount table. This way we can
461 * reference them only in the new table and do the switch to the new
462 * refcount table at once without producing an inconsistent state in
465 BLKDBG_EVENT(bs
->file
, BLKDBG_REFTABLE_GROW
);
467 /* Calculate the number of refcount blocks needed so far; this will be the
468 * basis for calculating the index of the first cluster used for the
469 * self-describing refcount structures which we are about to create.
471 * Because we reached this point, there cannot be any refcount entries for
472 * cluster_index or higher indices yet. However, because new_block has been
473 * allocated to describe that cluster (and it will assume this role later
474 * on), we cannot use that index; also, new_block may actually have a higher
475 * cluster index than cluster_index, so it needs to be taken into account
476 * here (and 1 needs to be added to its value because that cluster is used).
478 uint64_t blocks_used
= DIV_ROUND_UP(MAX(cluster_index
+ 1,
479 (new_block
>> s
->cluster_bits
) + 1),
480 s
->refcount_block_size
);
482 /* Create the new refcount table and blocks */
483 uint64_t meta_offset
= (blocks_used
* s
->refcount_block_size
) *
486 ret
= qcow2_refcount_area(bs
, meta_offset
, 0, false,
487 refcount_table_index
, new_block
);
492 ret
= load_refcount_block(bs
, new_block
, refcount_block
);
497 /* If we were trying to do the initial refcount update for some cluster
498 * allocation, we might have used the same clusters to store newly
499 * allocated metadata. Make the caller search some new space. */
503 if (*refcount_block
!= NULL
) {
504 qcow2_cache_put(s
->refcount_block_cache
, refcount_block
);
510 * Starting at @start_offset, this function creates new self-covering refcount
511 * structures: A new refcount table and refcount blocks which cover all of
512 * themselves, and a number of @additional_clusters beyond their end.
513 * @start_offset must be at the end of the image file, that is, there must be
514 * only empty space beyond it.
515 * If @exact_size is false, the refcount table will have 50 % more entries than
516 * necessary so it will not need to grow again soon.
517 * If @new_refblock_offset is not zero, it contains the offset of a refcount
518 * block that should be entered into the new refcount table at index
519 * @new_refblock_index.
521 * Returns: The offset after the new refcount structures (i.e. where the
522 * @additional_clusters may be placed) on success, -errno on error.
524 int64_t qcow2_refcount_area(BlockDriverState
*bs
, uint64_t start_offset
,
525 uint64_t additional_clusters
, bool exact_size
,
526 int new_refblock_index
,
527 uint64_t new_refblock_offset
)
529 BDRVQcow2State
*s
= bs
->opaque
;
530 uint64_t total_refblock_count_u64
, additional_refblock_count
;
531 int total_refblock_count
, table_size
, area_reftable_index
, table_clusters
;
533 uint64_t table_offset
, block_offset
, end_offset
;
537 assert(!(start_offset
% s
->cluster_size
));
539 qcow2_refcount_metadata_size(start_offset
/ s
->cluster_size
+
541 s
->cluster_size
, s
->refcount_order
,
542 !exact_size
, &total_refblock_count_u64
);
543 if (total_refblock_count_u64
> QCOW_MAX_REFTABLE_SIZE
) {
546 total_refblock_count
= total_refblock_count_u64
;
548 /* Index in the refcount table of the first refcount block to cover the area
549 * of refcount structures we are about to create; we know that
550 * @total_refblock_count can cover @start_offset, so this will definitely
551 * fit into an int. */
552 area_reftable_index
= (start_offset
/ s
->cluster_size
) /
553 s
->refcount_block_size
;
556 table_size
= total_refblock_count
;
558 table_size
= total_refblock_count
+
559 DIV_ROUND_UP(total_refblock_count
, 2);
561 /* The qcow2 file can only store the reftable size in number of clusters */
562 table_size
= ROUND_UP(table_size
, s
->cluster_size
/ sizeof(uint64_t));
563 table_clusters
= (table_size
* sizeof(uint64_t)) / s
->cluster_size
;
565 if (table_size
> QCOW_MAX_REFTABLE_SIZE
) {
569 new_table
= g_try_new0(uint64_t, table_size
);
571 assert(table_size
> 0);
572 if (new_table
== NULL
) {
577 /* Fill the new refcount table */
578 if (table_size
> s
->max_refcount_table_index
) {
579 /* We're actually growing the reftable */
580 memcpy(new_table
, s
->refcount_table
,
581 (s
->max_refcount_table_index
+ 1) * sizeof(uint64_t));
583 /* Improbable case: We're shrinking the reftable. However, the caller
584 * has assured us that there is only empty space beyond @start_offset,
585 * so we can simply drop all of the refblocks that won't fit into the
587 memcpy(new_table
, s
->refcount_table
, table_size
* sizeof(uint64_t));
590 if (new_refblock_offset
) {
591 assert(new_refblock_index
< total_refblock_count
);
592 new_table
[new_refblock_index
] = new_refblock_offset
;
595 /* Count how many new refblocks we have to create */
596 additional_refblock_count
= 0;
597 for (i
= area_reftable_index
; i
< total_refblock_count
; i
++) {
599 additional_refblock_count
++;
603 table_offset
= start_offset
+ additional_refblock_count
* s
->cluster_size
;
604 end_offset
= table_offset
+ table_clusters
* s
->cluster_size
;
606 /* Fill the refcount blocks, and create new ones, if necessary */
607 block_offset
= start_offset
;
608 for (i
= area_reftable_index
; i
< total_refblock_count
; i
++) {
610 uint64_t first_offset_covered
;
612 /* Reuse an existing refblock if possible, create a new one otherwise */
614 ret
= qcow2_cache_get(bs
, s
->refcount_block_cache
, new_table
[i
],
620 ret
= qcow2_cache_get_empty(bs
, s
->refcount_block_cache
,
621 block_offset
, &refblock_data
);
625 memset(refblock_data
, 0, s
->cluster_size
);
626 qcow2_cache_entry_mark_dirty(s
->refcount_block_cache
,
629 new_table
[i
] = block_offset
;
630 block_offset
+= s
->cluster_size
;
633 /* First host offset covered by this refblock */
634 first_offset_covered
= (uint64_t)i
* s
->refcount_block_size
*
636 if (first_offset_covered
< end_offset
) {
639 /* Set the refcount of all of the new refcount structures to 1 */
641 if (first_offset_covered
< start_offset
) {
642 assert(i
== area_reftable_index
);
643 j
= (start_offset
- first_offset_covered
) / s
->cluster_size
;
644 assert(j
< s
->refcount_block_size
);
649 end_index
= MIN((end_offset
- first_offset_covered
) /
651 s
->refcount_block_size
);
653 for (; j
< end_index
; j
++) {
654 /* The caller guaranteed us this space would be empty */
655 assert(s
->get_refcount(refblock_data
, j
) == 0);
656 s
->set_refcount(refblock_data
, j
, 1);
659 qcow2_cache_entry_mark_dirty(s
->refcount_block_cache
,
663 qcow2_cache_put(s
->refcount_block_cache
, &refblock_data
);
666 assert(block_offset
== table_offset
);
668 /* Write refcount blocks to disk */
669 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_ALLOC_WRITE_BLOCKS
);
670 ret
= qcow2_cache_flush(bs
, s
->refcount_block_cache
);
675 /* Write refcount table to disk */
676 for (i
= 0; i
< total_refblock_count
; i
++) {
677 cpu_to_be64s(&new_table
[i
]);
680 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_ALLOC_WRITE_TABLE
);
681 ret
= bdrv_pwrite_sync(bs
->file
, table_offset
, new_table
,
682 table_size
* sizeof(uint64_t));
687 for (i
= 0; i
< total_refblock_count
; i
++) {
688 be64_to_cpus(&new_table
[i
]);
691 /* Hook up the new refcount table in the qcow2 header */
696 data
.d64
= cpu_to_be64(table_offset
);
697 data
.d32
= cpu_to_be32(table_clusters
);
698 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_ALLOC_SWITCH_TABLE
);
699 ret
= bdrv_pwrite_sync(bs
->file
,
700 offsetof(QCowHeader
, refcount_table_offset
),
701 &data
, sizeof(data
));
706 /* And switch it in memory */
707 uint64_t old_table_offset
= s
->refcount_table_offset
;
708 uint64_t old_table_size
= s
->refcount_table_size
;
710 g_free(s
->refcount_table
);
711 s
->refcount_table
= new_table
;
712 s
->refcount_table_size
= table_size
;
713 s
->refcount_table_offset
= table_offset
;
714 update_max_refcount_table_index(s
);
716 /* Free old table. */
717 qcow2_free_clusters(bs
, old_table_offset
, old_table_size
* sizeof(uint64_t),
718 QCOW2_DISCARD_OTHER
);
727 void qcow2_process_discards(BlockDriverState
*bs
, int ret
)
729 BDRVQcow2State
*s
= bs
->opaque
;
730 Qcow2DiscardRegion
*d
, *next
;
732 QTAILQ_FOREACH_SAFE(d
, &s
->discards
, next
, next
) {
733 QTAILQ_REMOVE(&s
->discards
, d
, next
);
735 /* Discard is optional, ignore the return value */
737 bdrv_pdiscard(bs
->file
->bs
, d
->offset
, d
->bytes
);
744 static void update_refcount_discard(BlockDriverState
*bs
,
745 uint64_t offset
, uint64_t length
)
747 BDRVQcow2State
*s
= bs
->opaque
;
748 Qcow2DiscardRegion
*d
, *p
, *next
;
750 QTAILQ_FOREACH(d
, &s
->discards
, next
) {
751 uint64_t new_start
= MIN(offset
, d
->offset
);
752 uint64_t new_end
= MAX(offset
+ length
, d
->offset
+ d
->bytes
);
754 if (new_end
- new_start
<= length
+ d
->bytes
) {
755 /* There can't be any overlap, areas ending up here have no
756 * references any more and therefore shouldn't get freed another
758 assert(d
->bytes
+ length
== new_end
- new_start
);
759 d
->offset
= new_start
;
760 d
->bytes
= new_end
- new_start
;
765 d
= g_malloc(sizeof(*d
));
766 *d
= (Qcow2DiscardRegion
) {
771 QTAILQ_INSERT_TAIL(&s
->discards
, d
, next
);
774 /* Merge discard requests if they are adjacent now */
775 QTAILQ_FOREACH_SAFE(p
, &s
->discards
, next
, next
) {
777 || p
->offset
> d
->offset
+ d
->bytes
778 || d
->offset
> p
->offset
+ p
->bytes
)
783 /* Still no overlap possible */
784 assert(p
->offset
== d
->offset
+ d
->bytes
785 || d
->offset
== p
->offset
+ p
->bytes
);
787 QTAILQ_REMOVE(&s
->discards
, p
, next
);
788 d
->offset
= MIN(d
->offset
, p
->offset
);
789 d
->bytes
+= p
->bytes
;
794 /* XXX: cache several refcount block clusters ? */
795 /* @addend is the absolute value of the addend; if @decrease is set, @addend
796 * will be subtracted from the current refcount, otherwise it will be added */
797 static int QEMU_WARN_UNUSED_RESULT
update_refcount(BlockDriverState
*bs
,
802 enum qcow2_discard_type type
)
804 BDRVQcow2State
*s
= bs
->opaque
;
805 int64_t start
, last
, cluster_offset
;
806 void *refcount_block
= NULL
;
807 int64_t old_table_index
= -1;
811 fprintf(stderr
, "update_refcount: offset=%" PRId64
" size=%" PRId64
812 " addend=%s%" PRIu64
"\n", offset
, length
, decrease
? "-" : "",
817 } else if (length
== 0) {
822 qcow2_cache_set_dependency(bs
, s
->refcount_block_cache
,
826 start
= start_of_cluster(s
, offset
);
827 last
= start_of_cluster(s
, offset
+ length
- 1);
828 for(cluster_offset
= start
; cluster_offset
<= last
;
829 cluster_offset
+= s
->cluster_size
)
833 int64_t cluster_index
= cluster_offset
>> s
->cluster_bits
;
834 int64_t table_index
= cluster_index
>> s
->refcount_block_bits
;
836 /* Load the refcount block and allocate it if needed */
837 if (table_index
!= old_table_index
) {
838 if (refcount_block
) {
839 qcow2_cache_put(s
->refcount_block_cache
, &refcount_block
);
841 ret
= alloc_refcount_block(bs
, cluster_index
, &refcount_block
);
846 old_table_index
= table_index
;
848 qcow2_cache_entry_mark_dirty(s
->refcount_block_cache
, refcount_block
);
850 /* we can update the count and save it */
851 block_index
= cluster_index
& (s
->refcount_block_size
- 1);
853 refcount
= s
->get_refcount(refcount_block
, block_index
);
854 if (decrease
? (refcount
- addend
> refcount
)
855 : (refcount
+ addend
< refcount
||
856 refcount
+ addend
> s
->refcount_max
))
866 if (refcount
== 0 && cluster_index
< s
->free_cluster_index
) {
867 s
->free_cluster_index
= cluster_index
;
869 s
->set_refcount(refcount_block
, block_index
, refcount
);
874 table
= qcow2_cache_is_table_offset(s
->refcount_block_cache
,
877 qcow2_cache_put(s
->refcount_block_cache
, &refcount_block
);
878 qcow2_cache_discard(s
->refcount_block_cache
, table
);
881 table
= qcow2_cache_is_table_offset(s
->l2_table_cache
, offset
);
883 qcow2_cache_discard(s
->l2_table_cache
, table
);
886 if (s
->discard_passthrough
[type
]) {
887 update_refcount_discard(bs
, cluster_offset
, s
->cluster_size
);
894 if (!s
->cache_discards
) {
895 qcow2_process_discards(bs
, ret
);
898 /* Write last changed block to disk */
899 if (refcount_block
) {
900 qcow2_cache_put(s
->refcount_block_cache
, &refcount_block
);
904 * Try do undo any updates if an error is returned (This may succeed in
905 * some cases like ENOSPC for allocating a new refcount block)
909 dummy
= update_refcount(bs
, offset
, cluster_offset
- offset
, addend
,
910 !decrease
, QCOW2_DISCARD_NEVER
);
918 * Increases or decreases the refcount of a given cluster.
920 * @addend is the absolute value of the addend; if @decrease is set, @addend
921 * will be subtracted from the current refcount, otherwise it will be added.
923 * On success 0 is returned; on failure -errno is returned.
925 int qcow2_update_cluster_refcount(BlockDriverState
*bs
,
926 int64_t cluster_index
,
927 uint64_t addend
, bool decrease
,
928 enum qcow2_discard_type type
)
930 BDRVQcow2State
*s
= bs
->opaque
;
933 ret
= update_refcount(bs
, cluster_index
<< s
->cluster_bits
, 1, addend
,
944 /*********************************************************/
945 /* cluster allocation functions */
949 /* return < 0 if error */
950 static int64_t alloc_clusters_noref(BlockDriverState
*bs
, uint64_t size
)
952 BDRVQcow2State
*s
= bs
->opaque
;
953 uint64_t i
, nb_clusters
, refcount
;
956 /* We can't allocate clusters if they may still be queued for discard. */
957 if (s
->cache_discards
) {
958 qcow2_process_discards(bs
, 0);
961 nb_clusters
= size_to_clusters(s
, size
);
963 for(i
= 0; i
< nb_clusters
; i
++) {
964 uint64_t next_cluster_index
= s
->free_cluster_index
++;
965 ret
= qcow2_get_refcount(bs
, next_cluster_index
, &refcount
);
969 } else if (refcount
!= 0) {
974 /* Make sure that all offsets in the "allocated" range are representable
976 if (s
->free_cluster_index
> 0 &&
977 s
->free_cluster_index
- 1 > (INT64_MAX
>> s
->cluster_bits
))
983 fprintf(stderr
, "alloc_clusters: size=%" PRId64
" -> %" PRId64
"\n",
985 (s
->free_cluster_index
- nb_clusters
) << s
->cluster_bits
);
987 return (s
->free_cluster_index
- nb_clusters
) << s
->cluster_bits
;
990 int64_t qcow2_alloc_clusters(BlockDriverState
*bs
, uint64_t size
)
995 BLKDBG_EVENT(bs
->file
, BLKDBG_CLUSTER_ALLOC
);
997 offset
= alloc_clusters_noref(bs
, size
);
1002 ret
= update_refcount(bs
, offset
, size
, 1, false, QCOW2_DISCARD_NEVER
);
1003 } while (ret
== -EAGAIN
);
1012 int64_t qcow2_alloc_clusters_at(BlockDriverState
*bs
, uint64_t offset
,
1013 int64_t nb_clusters
)
1015 BDRVQcow2State
*s
= bs
->opaque
;
1016 uint64_t cluster_index
, refcount
;
1020 assert(nb_clusters
>= 0);
1021 if (nb_clusters
== 0) {
1026 /* Check how many clusters there are free */
1027 cluster_index
= offset
>> s
->cluster_bits
;
1028 for(i
= 0; i
< nb_clusters
; i
++) {
1029 ret
= qcow2_get_refcount(bs
, cluster_index
++, &refcount
);
1032 } else if (refcount
!= 0) {
1037 /* And then allocate them */
1038 ret
= update_refcount(bs
, offset
, i
<< s
->cluster_bits
, 1, false,
1039 QCOW2_DISCARD_NEVER
);
1040 } while (ret
== -EAGAIN
);
1049 /* only used to allocate compressed sectors. We try to allocate
1050 contiguous sectors. size must be <= cluster_size */
1051 int64_t qcow2_alloc_bytes(BlockDriverState
*bs
, int size
)
1053 BDRVQcow2State
*s
= bs
->opaque
;
1055 size_t free_in_cluster
;
1058 BLKDBG_EVENT(bs
->file
, BLKDBG_CLUSTER_ALLOC_BYTES
);
1059 assert(size
> 0 && size
<= s
->cluster_size
);
1060 assert(!s
->free_byte_offset
|| offset_into_cluster(s
, s
->free_byte_offset
));
1062 offset
= s
->free_byte_offset
;
1066 ret
= qcow2_get_refcount(bs
, offset
>> s
->cluster_bits
, &refcount
);
1071 if (refcount
== s
->refcount_max
) {
1076 free_in_cluster
= s
->cluster_size
- offset_into_cluster(s
, offset
);
1078 if (!offset
|| free_in_cluster
< size
) {
1079 int64_t new_cluster
= alloc_clusters_noref(bs
, s
->cluster_size
);
1080 if (new_cluster
< 0) {
1084 if (new_cluster
== 0) {
1085 qcow2_signal_corruption(bs
, true, -1, -1, "Preventing invalid "
1086 "allocation of compressed cluster "
1091 if (!offset
|| ROUND_UP(offset
, s
->cluster_size
) != new_cluster
) {
1092 offset
= new_cluster
;
1093 free_in_cluster
= s
->cluster_size
;
1095 free_in_cluster
+= s
->cluster_size
;
1100 ret
= update_refcount(bs
, offset
, size
, 1, false, QCOW2_DISCARD_NEVER
);
1104 } while (ret
== -EAGAIN
);
1109 /* The cluster refcount was incremented; refcount blocks must be flushed
1110 * before the caller's L2 table updates. */
1111 qcow2_cache_set_dependency(bs
, s
->l2_table_cache
, s
->refcount_block_cache
);
1113 s
->free_byte_offset
= offset
+ size
;
1114 if (!offset_into_cluster(s
, s
->free_byte_offset
)) {
1115 s
->free_byte_offset
= 0;
1121 void qcow2_free_clusters(BlockDriverState
*bs
,
1122 int64_t offset
, int64_t size
,
1123 enum qcow2_discard_type type
)
1127 BLKDBG_EVENT(bs
->file
, BLKDBG_CLUSTER_FREE
);
1128 ret
= update_refcount(bs
, offset
, size
, 1, true, type
);
1130 fprintf(stderr
, "qcow2_free_clusters failed: %s\n", strerror(-ret
));
1131 /* TODO Remember the clusters to free them later and avoid leaking */
1136 * Free a cluster using its L2 entry (handles clusters of all types, e.g.
1137 * normal cluster, compressed cluster, etc.)
1139 void qcow2_free_any_clusters(BlockDriverState
*bs
, uint64_t l2_entry
,
1140 int nb_clusters
, enum qcow2_discard_type type
)
1142 BDRVQcow2State
*s
= bs
->opaque
;
1144 switch (qcow2_get_cluster_type(l2_entry
)) {
1145 case QCOW2_CLUSTER_COMPRESSED
:
1148 nb_csectors
= ((l2_entry
>> s
->csize_shift
) &
1150 qcow2_free_clusters(bs
,
1151 (l2_entry
& s
->cluster_offset_mask
) & ~511,
1152 nb_csectors
* 512, type
);
1155 case QCOW2_CLUSTER_NORMAL
:
1156 case QCOW2_CLUSTER_ZERO_ALLOC
:
1157 if (offset_into_cluster(s
, l2_entry
& L2E_OFFSET_MASK
)) {
1158 qcow2_signal_corruption(bs
, false, -1, -1,
1159 "Cannot free unaligned cluster %#llx",
1160 l2_entry
& L2E_OFFSET_MASK
);
1162 qcow2_free_clusters(bs
, l2_entry
& L2E_OFFSET_MASK
,
1163 nb_clusters
<< s
->cluster_bits
, type
);
1166 case QCOW2_CLUSTER_ZERO_PLAIN
:
1167 case QCOW2_CLUSTER_UNALLOCATED
:
1176 /*********************************************************/
1177 /* snapshots and image creation */
1181 /* update the refcounts of snapshots and the copied flag */
1182 int qcow2_update_snapshot_refcount(BlockDriverState
*bs
,
1183 int64_t l1_table_offset
, int l1_size
, int addend
)
1185 BDRVQcow2State
*s
= bs
->opaque
;
1186 uint64_t *l1_table
, *l2_slice
, l2_offset
, entry
, l1_size2
, refcount
;
1187 bool l1_allocated
= false;
1188 int64_t old_entry
, old_l2_offset
;
1189 unsigned slice
, slice_size2
, n_slices
;
1190 int i
, j
, l1_modified
= 0, nb_csectors
;
1193 assert(addend
>= -1 && addend
<= 1);
1197 l1_size2
= l1_size
* sizeof(uint64_t);
1198 slice_size2
= s
->l2_slice_size
* sizeof(uint64_t);
1199 n_slices
= s
->cluster_size
/ slice_size2
;
1201 s
->cache_discards
= true;
1203 /* WARNING: qcow2_snapshot_goto relies on this function not using the
1204 * l1_table_offset when it is the current s->l1_table_offset! Be careful
1205 * when changing this! */
1206 if (l1_table_offset
!= s
->l1_table_offset
) {
1207 l1_table
= g_try_malloc0(align_offset(l1_size2
, 512));
1208 if (l1_size2
&& l1_table
== NULL
) {
1212 l1_allocated
= true;
1214 ret
= bdrv_pread(bs
->file
, l1_table_offset
, l1_table
, l1_size2
);
1219 for (i
= 0; i
< l1_size
; i
++) {
1220 be64_to_cpus(&l1_table
[i
]);
1223 assert(l1_size
== s
->l1_size
);
1224 l1_table
= s
->l1_table
;
1225 l1_allocated
= false;
1228 for (i
= 0; i
< l1_size
; i
++) {
1229 l2_offset
= l1_table
[i
];
1231 old_l2_offset
= l2_offset
;
1232 l2_offset
&= L1E_OFFSET_MASK
;
1234 if (offset_into_cluster(s
, l2_offset
)) {
1235 qcow2_signal_corruption(bs
, true, -1, -1, "L2 table offset %#"
1236 PRIx64
" unaligned (L1 index: %#x)",
1242 for (slice
= 0; slice
< n_slices
; slice
++) {
1243 ret
= qcow2_cache_get(bs
, s
->l2_table_cache
,
1244 l2_offset
+ slice
* slice_size2
,
1245 (void **) &l2_slice
);
1250 for (j
= 0; j
< s
->l2_slice_size
; j
++) {
1251 uint64_t cluster_index
;
1254 entry
= be64_to_cpu(l2_slice
[j
]);
1256 entry
&= ~QCOW_OFLAG_COPIED
;
1257 offset
= entry
& L2E_OFFSET_MASK
;
1259 switch (qcow2_get_cluster_type(entry
)) {
1260 case QCOW2_CLUSTER_COMPRESSED
:
1261 nb_csectors
= ((entry
>> s
->csize_shift
) &
1264 ret
= update_refcount(
1265 bs
, (entry
& s
->cluster_offset_mask
) & ~511,
1266 nb_csectors
* 512, abs(addend
), addend
< 0,
1267 QCOW2_DISCARD_SNAPSHOT
);
1272 /* compressed clusters are never modified */
1276 case QCOW2_CLUSTER_NORMAL
:
1277 case QCOW2_CLUSTER_ZERO_ALLOC
:
1278 if (offset_into_cluster(s
, offset
)) {
1279 /* Here l2_index means table (not slice) index */
1280 int l2_index
= slice
* s
->l2_slice_size
+ j
;
1281 qcow2_signal_corruption(
1282 bs
, true, -1, -1, "Cluster "
1283 "allocation offset %#" PRIx64
1284 " unaligned (L2 offset: %#"
1285 PRIx64
", L2 index: %#x)",
1286 offset
, l2_offset
, l2_index
);
1291 cluster_index
= offset
>> s
->cluster_bits
;
1292 assert(cluster_index
);
1294 ret
= qcow2_update_cluster_refcount(
1295 bs
, cluster_index
, abs(addend
), addend
< 0,
1296 QCOW2_DISCARD_SNAPSHOT
);
1302 ret
= qcow2_get_refcount(bs
, cluster_index
, &refcount
);
1308 case QCOW2_CLUSTER_ZERO_PLAIN
:
1309 case QCOW2_CLUSTER_UNALLOCATED
:
1317 if (refcount
== 1) {
1318 entry
|= QCOW_OFLAG_COPIED
;
1320 if (entry
!= old_entry
) {
1322 qcow2_cache_set_dependency(bs
, s
->l2_table_cache
,
1323 s
->refcount_block_cache
);
1325 l2_slice
[j
] = cpu_to_be64(entry
);
1326 qcow2_cache_entry_mark_dirty(s
->l2_table_cache
,
1331 qcow2_cache_put(s
->l2_table_cache
, (void **) &l2_slice
);
1335 ret
= qcow2_update_cluster_refcount(bs
, l2_offset
>>
1337 abs(addend
), addend
< 0,
1338 QCOW2_DISCARD_SNAPSHOT
);
1343 ret
= qcow2_get_refcount(bs
, l2_offset
>> s
->cluster_bits
,
1347 } else if (refcount
== 1) {
1348 l2_offset
|= QCOW_OFLAG_COPIED
;
1350 if (l2_offset
!= old_l2_offset
) {
1351 l1_table
[i
] = l2_offset
;
1357 ret
= bdrv_flush(bs
);
1360 qcow2_cache_put(s
->l2_table_cache
, (void **) &l2_slice
);
1363 s
->cache_discards
= false;
1364 qcow2_process_discards(bs
, ret
);
1366 /* Update L1 only if it isn't deleted anyway (addend = -1) */
1367 if (ret
== 0 && addend
>= 0 && l1_modified
) {
1368 for (i
= 0; i
< l1_size
; i
++) {
1369 cpu_to_be64s(&l1_table
[i
]);
1372 ret
= bdrv_pwrite_sync(bs
->file
, l1_table_offset
,
1373 l1_table
, l1_size2
);
1375 for (i
= 0; i
< l1_size
; i
++) {
1376 be64_to_cpus(&l1_table
[i
]);
1387 /*********************************************************/
1388 /* refcount checking functions */
1391 static uint64_t refcount_array_byte_size(BDRVQcow2State
*s
, uint64_t entries
)
1393 /* This assertion holds because there is no way we can address more than
1394 * 2^(64 - 9) clusters at once (with cluster size 512 = 2^9, and because
1395 * offsets have to be representable in bytes); due to every cluster
1396 * corresponding to one refcount entry, we are well below that limit */
1397 assert(entries
< (UINT64_C(1) << (64 - 9)));
1399 /* Thanks to the assertion this will not overflow, because
1400 * s->refcount_order < 7.
1401 * (note: x << s->refcount_order == x * s->refcount_bits) */
1402 return DIV_ROUND_UP(entries
<< s
->refcount_order
, 8);
1406 * Reallocates *array so that it can hold new_size entries. *size must contain
1407 * the current number of entries in *array. If the reallocation fails, *array
1408 * and *size will not be modified and -errno will be returned. If the
1409 * reallocation is successful, *array will be set to the new buffer, *size
1410 * will be set to new_size and 0 will be returned. The size of the reallocated
1411 * refcount array buffer will be aligned to a cluster boundary, and the newly
1412 * allocated area will be zeroed.
1414 static int realloc_refcount_array(BDRVQcow2State
*s
, void **array
,
1415 int64_t *size
, int64_t new_size
)
1417 int64_t old_byte_size
, new_byte_size
;
1420 /* Round to clusters so the array can be directly written to disk */
1421 old_byte_size
= size_to_clusters(s
, refcount_array_byte_size(s
, *size
))
1423 new_byte_size
= size_to_clusters(s
, refcount_array_byte_size(s
, new_size
))
1426 if (new_byte_size
== old_byte_size
) {
1431 assert(new_byte_size
> 0);
1433 if (new_byte_size
> SIZE_MAX
) {
1437 new_ptr
= g_try_realloc(*array
, new_byte_size
);
1442 if (new_byte_size
> old_byte_size
) {
1443 memset((char *)new_ptr
+ old_byte_size
, 0,
1444 new_byte_size
- old_byte_size
);
1454 * Increases the refcount for a range of clusters in a given refcount table.
1455 * This is used to construct a temporary refcount table out of L1 and L2 tables
1456 * which can be compared to the refcount table saved in the image.
1458 * Modifies the number of errors in res.
1460 int qcow2_inc_refcounts_imrt(BlockDriverState
*bs
, BdrvCheckResult
*res
,
1461 void **refcount_table
,
1462 int64_t *refcount_table_size
,
1463 int64_t offset
, int64_t size
)
1465 BDRVQcow2State
*s
= bs
->opaque
;
1466 uint64_t start
, last
, cluster_offset
, k
, refcount
;
1473 start
= start_of_cluster(s
, offset
);
1474 last
= start_of_cluster(s
, offset
+ size
- 1);
1475 for(cluster_offset
= start
; cluster_offset
<= last
;
1476 cluster_offset
+= s
->cluster_size
) {
1477 k
= cluster_offset
>> s
->cluster_bits
;
1478 if (k
>= *refcount_table_size
) {
1479 ret
= realloc_refcount_array(s
, refcount_table
,
1480 refcount_table_size
, k
+ 1);
1482 res
->check_errors
++;
1487 refcount
= s
->get_refcount(*refcount_table
, k
);
1488 if (refcount
== s
->refcount_max
) {
1489 fprintf(stderr
, "ERROR: overflow cluster offset=0x%" PRIx64
1490 "\n", cluster_offset
);
1491 fprintf(stderr
, "Use qemu-img amend to increase the refcount entry "
1492 "width or qemu-img convert to create a clean copy if the "
1493 "image cannot be opened for writing\n");
1497 s
->set_refcount(*refcount_table
, k
, refcount
+ 1);
1503 /* Flags for check_refcounts_l1() and check_refcounts_l2() */
1505 CHECK_FRAG_INFO
= 0x2, /* update BlockFragInfo counters */
1509 * Increases the refcount in the given refcount table for the all clusters
1510 * referenced in the L2 table. While doing so, performs some checks on L2
1513 * Returns the number of errors found by the checks or -errno if an internal
1516 static int check_refcounts_l2(BlockDriverState
*bs
, BdrvCheckResult
*res
,
1517 void **refcount_table
,
1518 int64_t *refcount_table_size
, int64_t l2_offset
,
1519 int flags
, BdrvCheckMode fix
)
1521 BDRVQcow2State
*s
= bs
->opaque
;
1522 uint64_t *l2_table
, l2_entry
;
1523 uint64_t next_contiguous_offset
= 0;
1524 int i
, l2_size
, nb_csectors
, ret
;
1526 /* Read L2 table from disk */
1527 l2_size
= s
->l2_size
* sizeof(uint64_t);
1528 l2_table
= g_malloc(l2_size
);
1530 ret
= bdrv_pread(bs
->file
, l2_offset
, l2_table
, l2_size
);
1532 fprintf(stderr
, "ERROR: I/O error in check_refcounts_l2\n");
1533 res
->check_errors
++;
1537 /* Do the actual checks */
1538 for(i
= 0; i
< s
->l2_size
; i
++) {
1539 l2_entry
= be64_to_cpu(l2_table
[i
]);
1541 switch (qcow2_get_cluster_type(l2_entry
)) {
1542 case QCOW2_CLUSTER_COMPRESSED
:
1543 /* Compressed clusters don't have QCOW_OFLAG_COPIED */
1544 if (l2_entry
& QCOW_OFLAG_COPIED
) {
1545 fprintf(stderr
, "ERROR: cluster %" PRId64
": "
1546 "copied flag must never be set for compressed "
1547 "clusters\n", l2_entry
>> s
->cluster_bits
);
1548 l2_entry
&= ~QCOW_OFLAG_COPIED
;
1552 /* Mark cluster as used */
1553 nb_csectors
= ((l2_entry
>> s
->csize_shift
) &
1555 l2_entry
&= s
->cluster_offset_mask
;
1556 ret
= qcow2_inc_refcounts_imrt(bs
, res
,
1557 refcount_table
, refcount_table_size
,
1558 l2_entry
& ~511, nb_csectors
* 512);
1563 if (flags
& CHECK_FRAG_INFO
) {
1564 res
->bfi
.allocated_clusters
++;
1565 res
->bfi
.compressed_clusters
++;
1567 /* Compressed clusters are fragmented by nature. Since they
1568 * take up sub-sector space but we only have sector granularity
1569 * I/O we need to re-read the same sectors even for adjacent
1570 * compressed clusters.
1572 res
->bfi
.fragmented_clusters
++;
1576 case QCOW2_CLUSTER_ZERO_ALLOC
:
1577 case QCOW2_CLUSTER_NORMAL
:
1579 uint64_t offset
= l2_entry
& L2E_OFFSET_MASK
;
1581 if (flags
& CHECK_FRAG_INFO
) {
1582 res
->bfi
.allocated_clusters
++;
1583 if (next_contiguous_offset
&&
1584 offset
!= next_contiguous_offset
) {
1585 res
->bfi
.fragmented_clusters
++;
1587 next_contiguous_offset
= offset
+ s
->cluster_size
;
1590 /* Correct offsets are cluster aligned */
1591 if (offset_into_cluster(s
, offset
)) {
1592 if (qcow2_get_cluster_type(l2_entry
) ==
1593 QCOW2_CLUSTER_ZERO_ALLOC
)
1595 fprintf(stderr
, "%s offset=%" PRIx64
": Preallocated zero "
1596 "cluster is not properly aligned; L2 entry "
1598 fix
& BDRV_FIX_ERRORS
? "Repairing" : "ERROR",
1600 if (fix
& BDRV_FIX_ERRORS
) {
1601 uint64_t l2e_offset
=
1602 l2_offset
+ (uint64_t)i
* sizeof(uint64_t);
1604 l2_entry
= QCOW_OFLAG_ZERO
;
1605 l2_table
[i
] = cpu_to_be64(l2_entry
);
1606 ret
= qcow2_pre_write_overlap_check(bs
,
1607 QCOW2_OL_ACTIVE_L2
| QCOW2_OL_INACTIVE_L2
,
1608 l2e_offset
, sizeof(uint64_t));
1610 fprintf(stderr
, "ERROR: Overlap check failed\n");
1611 res
->check_errors
++;
1612 /* Something is seriously wrong, so abort checking
1617 ret
= bdrv_pwrite_sync(bs
->file
, l2e_offset
,
1618 &l2_table
[i
], sizeof(uint64_t));
1620 fprintf(stderr
, "ERROR: Failed to overwrite L2 "
1621 "table entry: %s\n", strerror(-ret
));
1622 res
->check_errors
++;
1623 /* Do not abort, continue checking the rest of this
1624 * L2 table's entries */
1626 res
->corruptions_fixed
++;
1627 /* Skip marking the cluster as used
1628 * (it is unused now) */
1635 fprintf(stderr
, "ERROR offset=%" PRIx64
": Data cluster is "
1636 "not properly aligned; L2 entry corrupted.\n", offset
);
1641 /* Mark cluster as used */
1642 ret
= qcow2_inc_refcounts_imrt(bs
, res
,
1643 refcount_table
, refcount_table_size
,
1644 offset
, s
->cluster_size
);
1651 case QCOW2_CLUSTER_ZERO_PLAIN
:
1652 case QCOW2_CLUSTER_UNALLOCATED
:
1669 * Increases the refcount for the L1 table, its L2 tables and all referenced
1670 * clusters in the given refcount table. While doing so, performs some checks
1671 * on L1 and L2 entries.
1673 * Returns the number of errors found by the checks or -errno if an internal
1676 static int check_refcounts_l1(BlockDriverState
*bs
,
1677 BdrvCheckResult
*res
,
1678 void **refcount_table
,
1679 int64_t *refcount_table_size
,
1680 int64_t l1_table_offset
, int l1_size
,
1681 int flags
, BdrvCheckMode fix
)
1683 BDRVQcow2State
*s
= bs
->opaque
;
1684 uint64_t *l1_table
= NULL
, l2_offset
, l1_size2
;
1687 l1_size2
= l1_size
* sizeof(uint64_t);
1689 /* Mark L1 table as used */
1690 ret
= qcow2_inc_refcounts_imrt(bs
, res
, refcount_table
, refcount_table_size
,
1691 l1_table_offset
, l1_size2
);
1696 /* Read L1 table entries from disk */
1698 l1_table
= g_try_malloc(l1_size2
);
1699 if (l1_table
== NULL
) {
1701 res
->check_errors
++;
1704 ret
= bdrv_pread(bs
->file
, l1_table_offset
, l1_table
, l1_size2
);
1706 fprintf(stderr
, "ERROR: I/O error in check_refcounts_l1\n");
1707 res
->check_errors
++;
1710 for(i
= 0;i
< l1_size
; i
++)
1711 be64_to_cpus(&l1_table
[i
]);
1714 /* Do the actual checks */
1715 for(i
= 0; i
< l1_size
; i
++) {
1716 l2_offset
= l1_table
[i
];
1718 /* Mark L2 table as used */
1719 l2_offset
&= L1E_OFFSET_MASK
;
1720 ret
= qcow2_inc_refcounts_imrt(bs
, res
,
1721 refcount_table
, refcount_table_size
,
1722 l2_offset
, s
->cluster_size
);
1727 /* L2 tables are cluster aligned */
1728 if (offset_into_cluster(s
, l2_offset
)) {
1729 fprintf(stderr
, "ERROR l2_offset=%" PRIx64
": Table is not "
1730 "cluster aligned; L1 entry corrupted\n", l2_offset
);
1734 /* Process and check L2 entries */
1735 ret
= check_refcounts_l2(bs
, res
, refcount_table
,
1736 refcount_table_size
, l2_offset
, flags
,
1752 * Checks the OFLAG_COPIED flag for all L1 and L2 entries.
1754 * This function does not print an error message nor does it increment
1755 * check_errors if qcow2_get_refcount fails (this is because such an error will
1756 * have been already detected and sufficiently signaled by the calling function
1757 * (qcow2_check_refcounts) by the time this function is called).
1759 static int check_oflag_copied(BlockDriverState
*bs
, BdrvCheckResult
*res
,
1762 BDRVQcow2State
*s
= bs
->opaque
;
1763 uint64_t *l2_table
= qemu_blockalign(bs
, s
->cluster_size
);
1768 for (i
= 0; i
< s
->l1_size
; i
++) {
1769 uint64_t l1_entry
= s
->l1_table
[i
];
1770 uint64_t l2_offset
= l1_entry
& L1E_OFFSET_MASK
;
1771 bool l2_dirty
= false;
1777 ret
= qcow2_get_refcount(bs
, l2_offset
>> s
->cluster_bits
,
1780 /* don't print message nor increment check_errors */
1783 if ((refcount
== 1) != ((l1_entry
& QCOW_OFLAG_COPIED
) != 0)) {
1784 fprintf(stderr
, "%s OFLAG_COPIED L2 cluster: l1_index=%d "
1785 "l1_entry=%" PRIx64
" refcount=%" PRIu64
"\n",
1786 fix
& BDRV_FIX_ERRORS
? "Repairing" :
1788 i
, l1_entry
, refcount
);
1789 if (fix
& BDRV_FIX_ERRORS
) {
1790 s
->l1_table
[i
] = refcount
== 1
1791 ? l1_entry
| QCOW_OFLAG_COPIED
1792 : l1_entry
& ~QCOW_OFLAG_COPIED
;
1793 ret
= qcow2_write_l1_entry(bs
, i
);
1795 res
->check_errors
++;
1798 res
->corruptions_fixed
++;
1804 ret
= bdrv_pread(bs
->file
, l2_offset
, l2_table
,
1805 s
->l2_size
* sizeof(uint64_t));
1807 fprintf(stderr
, "ERROR: Could not read L2 table: %s\n",
1809 res
->check_errors
++;
1813 for (j
= 0; j
< s
->l2_size
; j
++) {
1814 uint64_t l2_entry
= be64_to_cpu(l2_table
[j
]);
1815 uint64_t data_offset
= l2_entry
& L2E_OFFSET_MASK
;
1816 QCow2ClusterType cluster_type
= qcow2_get_cluster_type(l2_entry
);
1818 if (cluster_type
== QCOW2_CLUSTER_NORMAL
||
1819 cluster_type
== QCOW2_CLUSTER_ZERO_ALLOC
) {
1820 ret
= qcow2_get_refcount(bs
,
1821 data_offset
>> s
->cluster_bits
,
1824 /* don't print message nor increment check_errors */
1827 if ((refcount
== 1) != ((l2_entry
& QCOW_OFLAG_COPIED
) != 0)) {
1828 fprintf(stderr
, "%s OFLAG_COPIED data cluster: "
1829 "l2_entry=%" PRIx64
" refcount=%" PRIu64
"\n",
1830 fix
& BDRV_FIX_ERRORS
? "Repairing" :
1832 l2_entry
, refcount
);
1833 if (fix
& BDRV_FIX_ERRORS
) {
1834 l2_table
[j
] = cpu_to_be64(refcount
== 1
1835 ? l2_entry
| QCOW_OFLAG_COPIED
1836 : l2_entry
& ~QCOW_OFLAG_COPIED
);
1838 res
->corruptions_fixed
++;
1847 ret
= qcow2_pre_write_overlap_check(bs
, QCOW2_OL_ACTIVE_L2
,
1848 l2_offset
, s
->cluster_size
);
1850 fprintf(stderr
, "ERROR: Could not write L2 table; metadata "
1851 "overlap check failed: %s\n", strerror(-ret
));
1852 res
->check_errors
++;
1856 ret
= bdrv_pwrite(bs
->file
, l2_offset
, l2_table
,
1859 fprintf(stderr
, "ERROR: Could not write L2 table: %s\n",
1861 res
->check_errors
++;
1870 qemu_vfree(l2_table
);
1875 * Checks consistency of refblocks and accounts for each refblock in
1878 static int check_refblocks(BlockDriverState
*bs
, BdrvCheckResult
*res
,
1879 BdrvCheckMode fix
, bool *rebuild
,
1880 void **refcount_table
, int64_t *nb_clusters
)
1882 BDRVQcow2State
*s
= bs
->opaque
;
1886 for(i
= 0; i
< s
->refcount_table_size
; i
++) {
1887 uint64_t offset
, cluster
;
1888 offset
= s
->refcount_table
[i
];
1889 cluster
= offset
>> s
->cluster_bits
;
1891 /* Refcount blocks are cluster aligned */
1892 if (offset_into_cluster(s
, offset
)) {
1893 fprintf(stderr
, "ERROR refcount block %" PRId64
" is not "
1894 "cluster aligned; refcount table entry corrupted\n", i
);
1900 if (cluster
>= *nb_clusters
) {
1901 fprintf(stderr
, "%s refcount block %" PRId64
" is outside image\n",
1902 fix
& BDRV_FIX_ERRORS
? "Repairing" : "ERROR", i
);
1904 if (fix
& BDRV_FIX_ERRORS
) {
1905 int64_t new_nb_clusters
;
1906 Error
*local_err
= NULL
;
1908 if (offset
> INT64_MAX
- s
->cluster_size
) {
1913 ret
= bdrv_truncate(bs
->file
, offset
+ s
->cluster_size
,
1914 PREALLOC_MODE_OFF
, &local_err
);
1916 error_report_err(local_err
);
1919 size
= bdrv_getlength(bs
->file
->bs
);
1925 new_nb_clusters
= size_to_clusters(s
, size
);
1926 assert(new_nb_clusters
>= *nb_clusters
);
1928 ret
= realloc_refcount_array(s
, refcount_table
,
1929 nb_clusters
, new_nb_clusters
);
1931 res
->check_errors
++;
1935 if (cluster
>= *nb_clusters
) {
1940 res
->corruptions_fixed
++;
1941 ret
= qcow2_inc_refcounts_imrt(bs
, res
,
1942 refcount_table
, nb_clusters
,
1943 offset
, s
->cluster_size
);
1947 /* No need to check whether the refcount is now greater than 1:
1948 * This area was just allocated and zeroed, so it can only be
1949 * exactly 1 after qcow2_inc_refcounts_imrt() */
1955 fprintf(stderr
, "ERROR could not resize image: %s\n",
1964 ret
= qcow2_inc_refcounts_imrt(bs
, res
, refcount_table
, nb_clusters
,
1965 offset
, s
->cluster_size
);
1969 if (s
->get_refcount(*refcount_table
, cluster
) != 1) {
1970 fprintf(stderr
, "ERROR refcount block %" PRId64
1971 " refcount=%" PRIu64
"\n", i
,
1972 s
->get_refcount(*refcount_table
, cluster
));
1983 * Calculates an in-memory refcount table.
1985 static int calculate_refcounts(BlockDriverState
*bs
, BdrvCheckResult
*res
,
1986 BdrvCheckMode fix
, bool *rebuild
,
1987 void **refcount_table
, int64_t *nb_clusters
)
1989 BDRVQcow2State
*s
= bs
->opaque
;
1994 if (!*refcount_table
) {
1995 int64_t old_size
= 0;
1996 ret
= realloc_refcount_array(s
, refcount_table
,
1997 &old_size
, *nb_clusters
);
1999 res
->check_errors
++;
2005 ret
= qcow2_inc_refcounts_imrt(bs
, res
, refcount_table
, nb_clusters
,
2006 0, s
->cluster_size
);
2011 /* current L1 table */
2012 ret
= check_refcounts_l1(bs
, res
, refcount_table
, nb_clusters
,
2013 s
->l1_table_offset
, s
->l1_size
, CHECK_FRAG_INFO
,
2020 for (i
= 0; i
< s
->nb_snapshots
; i
++) {
2021 sn
= s
->snapshots
+ i
;
2022 ret
= check_refcounts_l1(bs
, res
, refcount_table
, nb_clusters
,
2023 sn
->l1_table_offset
, sn
->l1_size
, 0, fix
);
2028 ret
= qcow2_inc_refcounts_imrt(bs
, res
, refcount_table
, nb_clusters
,
2029 s
->snapshots_offset
, s
->snapshots_size
);
2035 ret
= qcow2_inc_refcounts_imrt(bs
, res
, refcount_table
, nb_clusters
,
2036 s
->refcount_table_offset
,
2037 s
->refcount_table_size
* sizeof(uint64_t));
2043 if (s
->crypto_header
.length
) {
2044 ret
= qcow2_inc_refcounts_imrt(bs
, res
, refcount_table
, nb_clusters
,
2045 s
->crypto_header
.offset
,
2046 s
->crypto_header
.length
);
2053 ret
= qcow2_check_bitmaps_refcounts(bs
, res
, refcount_table
, nb_clusters
);
2058 return check_refblocks(bs
, res
, fix
, rebuild
, refcount_table
, nb_clusters
);
2062 * Compares the actual reference count for each cluster in the image against the
2063 * refcount as reported by the refcount structures on-disk.
2065 static void compare_refcounts(BlockDriverState
*bs
, BdrvCheckResult
*res
,
2066 BdrvCheckMode fix
, bool *rebuild
,
2067 int64_t *highest_cluster
,
2068 void *refcount_table
, int64_t nb_clusters
)
2070 BDRVQcow2State
*s
= bs
->opaque
;
2072 uint64_t refcount1
, refcount2
;
2075 for (i
= 0, *highest_cluster
= 0; i
< nb_clusters
; i
++) {
2076 ret
= qcow2_get_refcount(bs
, i
, &refcount1
);
2078 fprintf(stderr
, "Can't get refcount for cluster %" PRId64
": %s\n",
2080 res
->check_errors
++;
2084 refcount2
= s
->get_refcount(refcount_table
, i
);
2086 if (refcount1
> 0 || refcount2
> 0) {
2087 *highest_cluster
= i
;
2090 if (refcount1
!= refcount2
) {
2091 /* Check if we're allowed to fix the mismatch */
2092 int *num_fixed
= NULL
;
2093 if (refcount1
== 0) {
2095 } else if (refcount1
> refcount2
&& (fix
& BDRV_FIX_LEAKS
)) {
2096 num_fixed
= &res
->leaks_fixed
;
2097 } else if (refcount1
< refcount2
&& (fix
& BDRV_FIX_ERRORS
)) {
2098 num_fixed
= &res
->corruptions_fixed
;
2101 fprintf(stderr
, "%s cluster %" PRId64
" refcount=%" PRIu64
2102 " reference=%" PRIu64
"\n",
2103 num_fixed
!= NULL
? "Repairing" :
2104 refcount1
< refcount2
? "ERROR" :
2106 i
, refcount1
, refcount2
);
2109 ret
= update_refcount(bs
, i
<< s
->cluster_bits
, 1,
2110 refcount_diff(refcount1
, refcount2
),
2111 refcount1
> refcount2
,
2112 QCOW2_DISCARD_ALWAYS
);
2119 /* And if we couldn't, print an error */
2120 if (refcount1
< refcount2
) {
2130 * Allocates clusters using an in-memory refcount table (IMRT) in contrast to
2131 * the on-disk refcount structures.
2133 * On input, *first_free_cluster tells where to start looking, and need not
2134 * actually be a free cluster; the returned offset will not be before that
2135 * cluster. On output, *first_free_cluster points to the first gap found, even
2136 * if that gap was too small to be used as the returned offset.
2138 * Note that *first_free_cluster is a cluster index whereas the return value is
2141 static int64_t alloc_clusters_imrt(BlockDriverState
*bs
,
2143 void **refcount_table
,
2144 int64_t *imrt_nb_clusters
,
2145 int64_t *first_free_cluster
)
2147 BDRVQcow2State
*s
= bs
->opaque
;
2148 int64_t cluster
= *first_free_cluster
, i
;
2149 bool first_gap
= true;
2150 int contiguous_free_clusters
;
2153 /* Starting at *first_free_cluster, find a range of at least cluster_count
2154 * continuously free clusters */
2155 for (contiguous_free_clusters
= 0;
2156 cluster
< *imrt_nb_clusters
&&
2157 contiguous_free_clusters
< cluster_count
;
2160 if (!s
->get_refcount(*refcount_table
, cluster
)) {
2161 contiguous_free_clusters
++;
2163 /* If this is the first free cluster found, update
2164 * *first_free_cluster accordingly */
2165 *first_free_cluster
= cluster
;
2168 } else if (contiguous_free_clusters
) {
2169 contiguous_free_clusters
= 0;
2173 /* If contiguous_free_clusters is greater than zero, it contains the number
2174 * of continuously free clusters until the current cluster; the first free
2175 * cluster in the current "gap" is therefore
2176 * cluster - contiguous_free_clusters */
2178 /* If no such range could be found, grow the in-memory refcount table
2179 * accordingly to append free clusters at the end of the image */
2180 if (contiguous_free_clusters
< cluster_count
) {
2181 /* contiguous_free_clusters clusters are already empty at the image end;
2182 * we need cluster_count clusters; therefore, we have to allocate
2183 * cluster_count - contiguous_free_clusters new clusters at the end of
2184 * the image (which is the current value of cluster; note that cluster
2185 * may exceed old_imrt_nb_clusters if *first_free_cluster pointed beyond
2187 ret
= realloc_refcount_array(s
, refcount_table
, imrt_nb_clusters
,
2188 cluster
+ cluster_count
2189 - contiguous_free_clusters
);
2195 /* Go back to the first free cluster */
2196 cluster
-= contiguous_free_clusters
;
2197 for (i
= 0; i
< cluster_count
; i
++) {
2198 s
->set_refcount(*refcount_table
, cluster
+ i
, 1);
2201 return cluster
<< s
->cluster_bits
;
2205 * Creates a new refcount structure based solely on the in-memory information
2206 * given through *refcount_table. All necessary allocations will be reflected
2209 * On success, the old refcount structure is leaked (it will be covered by the
2210 * new refcount structure).
2212 static int rebuild_refcount_structure(BlockDriverState
*bs
,
2213 BdrvCheckResult
*res
,
2214 void **refcount_table
,
2215 int64_t *nb_clusters
)
2217 BDRVQcow2State
*s
= bs
->opaque
;
2218 int64_t first_free_cluster
= 0, reftable_offset
= -1, cluster
= 0;
2219 int64_t refblock_offset
, refblock_start
, refblock_index
;
2220 uint32_t reftable_size
= 0;
2221 uint64_t *on_disk_reftable
= NULL
;
2222 void *on_disk_refblock
;
2225 uint64_t reftable_offset
;
2226 uint32_t reftable_clusters
;
2227 } QEMU_PACKED reftable_offset_and_clusters
;
2229 qcow2_cache_empty(bs
, s
->refcount_block_cache
);
2232 for (; cluster
< *nb_clusters
; cluster
++) {
2233 if (!s
->get_refcount(*refcount_table
, cluster
)) {
2237 refblock_index
= cluster
>> s
->refcount_block_bits
;
2238 refblock_start
= refblock_index
<< s
->refcount_block_bits
;
2240 /* Don't allocate a cluster in a refblock already written to disk */
2241 if (first_free_cluster
< refblock_start
) {
2242 first_free_cluster
= refblock_start
;
2244 refblock_offset
= alloc_clusters_imrt(bs
, 1, refcount_table
,
2245 nb_clusters
, &first_free_cluster
);
2246 if (refblock_offset
< 0) {
2247 fprintf(stderr
, "ERROR allocating refblock: %s\n",
2248 strerror(-refblock_offset
));
2249 res
->check_errors
++;
2250 ret
= refblock_offset
;
2254 if (reftable_size
<= refblock_index
) {
2255 uint32_t old_reftable_size
= reftable_size
;
2256 uint64_t *new_on_disk_reftable
;
2258 reftable_size
= ROUND_UP((refblock_index
+ 1) * sizeof(uint64_t),
2259 s
->cluster_size
) / sizeof(uint64_t);
2260 new_on_disk_reftable
= g_try_realloc(on_disk_reftable
,
2263 if (!new_on_disk_reftable
) {
2264 res
->check_errors
++;
2268 on_disk_reftable
= new_on_disk_reftable
;
2270 memset(on_disk_reftable
+ old_reftable_size
, 0,
2271 (reftable_size
- old_reftable_size
) * sizeof(uint64_t));
2273 /* The offset we have for the reftable is now no longer valid;
2274 * this will leak that range, but we can easily fix that by running
2275 * a leak-fixing check after this rebuild operation */
2276 reftable_offset
= -1;
2278 assert(on_disk_reftable
);
2280 on_disk_reftable
[refblock_index
] = refblock_offset
;
2282 /* If this is apparently the last refblock (for now), try to squeeze the
2284 if (refblock_index
== (*nb_clusters
- 1) >> s
->refcount_block_bits
&&
2285 reftable_offset
< 0)
2287 uint64_t reftable_clusters
= size_to_clusters(s
, reftable_size
*
2289 reftable_offset
= alloc_clusters_imrt(bs
, reftable_clusters
,
2290 refcount_table
, nb_clusters
,
2291 &first_free_cluster
);
2292 if (reftable_offset
< 0) {
2293 fprintf(stderr
, "ERROR allocating reftable: %s\n",
2294 strerror(-reftable_offset
));
2295 res
->check_errors
++;
2296 ret
= reftable_offset
;
2301 ret
= qcow2_pre_write_overlap_check(bs
, 0, refblock_offset
,
2304 fprintf(stderr
, "ERROR writing refblock: %s\n", strerror(-ret
));
2308 /* The size of *refcount_table is always cluster-aligned, therefore the
2309 * write operation will not overflow */
2310 on_disk_refblock
= (void *)((char *) *refcount_table
+
2311 refblock_index
* s
->cluster_size
);
2313 ret
= bdrv_write(bs
->file
, refblock_offset
/ BDRV_SECTOR_SIZE
,
2314 on_disk_refblock
, s
->cluster_sectors
);
2316 fprintf(stderr
, "ERROR writing refblock: %s\n", strerror(-ret
));
2320 /* Go to the end of this refblock */
2321 cluster
= refblock_start
+ s
->refcount_block_size
- 1;
2324 if (reftable_offset
< 0) {
2325 uint64_t post_refblock_start
, reftable_clusters
;
2327 post_refblock_start
= ROUND_UP(*nb_clusters
, s
->refcount_block_size
);
2328 reftable_clusters
= size_to_clusters(s
,
2329 reftable_size
* sizeof(uint64_t));
2330 /* Not pretty but simple */
2331 if (first_free_cluster
< post_refblock_start
) {
2332 first_free_cluster
= post_refblock_start
;
2334 reftable_offset
= alloc_clusters_imrt(bs
, reftable_clusters
,
2335 refcount_table
, nb_clusters
,
2336 &first_free_cluster
);
2337 if (reftable_offset
< 0) {
2338 fprintf(stderr
, "ERROR allocating reftable: %s\n",
2339 strerror(-reftable_offset
));
2340 res
->check_errors
++;
2341 ret
= reftable_offset
;
2345 goto write_refblocks
;
2348 for (refblock_index
= 0; refblock_index
< reftable_size
; refblock_index
++) {
2349 cpu_to_be64s(&on_disk_reftable
[refblock_index
]);
2352 ret
= qcow2_pre_write_overlap_check(bs
, 0, reftable_offset
,
2353 reftable_size
* sizeof(uint64_t));
2355 fprintf(stderr
, "ERROR writing reftable: %s\n", strerror(-ret
));
2359 assert(reftable_size
< INT_MAX
/ sizeof(uint64_t));
2360 ret
= bdrv_pwrite(bs
->file
, reftable_offset
, on_disk_reftable
,
2361 reftable_size
* sizeof(uint64_t));
2363 fprintf(stderr
, "ERROR writing reftable: %s\n", strerror(-ret
));
2367 /* Enter new reftable into the image header */
2368 reftable_offset_and_clusters
.reftable_offset
= cpu_to_be64(reftable_offset
);
2369 reftable_offset_and_clusters
.reftable_clusters
=
2370 cpu_to_be32(size_to_clusters(s
, reftable_size
* sizeof(uint64_t)));
2371 ret
= bdrv_pwrite_sync(bs
->file
,
2372 offsetof(QCowHeader
, refcount_table_offset
),
2373 &reftable_offset_and_clusters
,
2374 sizeof(reftable_offset_and_clusters
));
2376 fprintf(stderr
, "ERROR setting reftable: %s\n", strerror(-ret
));
2380 for (refblock_index
= 0; refblock_index
< reftable_size
; refblock_index
++) {
2381 be64_to_cpus(&on_disk_reftable
[refblock_index
]);
2383 s
->refcount_table
= on_disk_reftable
;
2384 s
->refcount_table_offset
= reftable_offset
;
2385 s
->refcount_table_size
= reftable_size
;
2386 update_max_refcount_table_index(s
);
2391 g_free(on_disk_reftable
);
2396 * Checks an image for refcount consistency.
2398 * Returns 0 if no errors are found, the number of errors in case the image is
2399 * detected as corrupted, and -errno when an internal error occurred.
2401 int qcow2_check_refcounts(BlockDriverState
*bs
, BdrvCheckResult
*res
,
2404 BDRVQcow2State
*s
= bs
->opaque
;
2405 BdrvCheckResult pre_compare_res
;
2406 int64_t size
, highest_cluster
, nb_clusters
;
2407 void *refcount_table
= NULL
;
2408 bool rebuild
= false;
2411 size
= bdrv_getlength(bs
->file
->bs
);
2413 res
->check_errors
++;
2417 nb_clusters
= size_to_clusters(s
, size
);
2418 if (nb_clusters
> INT_MAX
) {
2419 res
->check_errors
++;
2423 res
->bfi
.total_clusters
=
2424 size_to_clusters(s
, bs
->total_sectors
* BDRV_SECTOR_SIZE
);
2426 ret
= calculate_refcounts(bs
, res
, fix
, &rebuild
, &refcount_table
,
2432 /* In case we don't need to rebuild the refcount structure (but want to fix
2433 * something), this function is immediately called again, in which case the
2434 * result should be ignored */
2435 pre_compare_res
= *res
;
2436 compare_refcounts(bs
, res
, 0, &rebuild
, &highest_cluster
, refcount_table
,
2439 if (rebuild
&& (fix
& BDRV_FIX_ERRORS
)) {
2440 BdrvCheckResult old_res
= *res
;
2441 int fresh_leaks
= 0;
2443 fprintf(stderr
, "Rebuilding refcount structure\n");
2444 ret
= rebuild_refcount_structure(bs
, res
, &refcount_table
,
2450 res
->corruptions
= 0;
2453 /* Because the old reftable has been exchanged for a new one the
2454 * references have to be recalculated */
2456 memset(refcount_table
, 0, refcount_array_byte_size(s
, nb_clusters
));
2457 ret
= calculate_refcounts(bs
, res
, 0, &rebuild
, &refcount_table
,
2463 if (fix
& BDRV_FIX_LEAKS
) {
2464 /* The old refcount structures are now leaked, fix it; the result
2465 * can be ignored, aside from leaks which were introduced by
2466 * rebuild_refcount_structure() that could not be fixed */
2467 BdrvCheckResult saved_res
= *res
;
2468 *res
= (BdrvCheckResult
){ 0 };
2470 compare_refcounts(bs
, res
, BDRV_FIX_LEAKS
, &rebuild
,
2471 &highest_cluster
, refcount_table
, nb_clusters
);
2473 fprintf(stderr
, "ERROR rebuilt refcount structure is still "
2477 /* Any leaks accounted for here were introduced by
2478 * rebuild_refcount_structure() because that function has created a
2479 * new refcount structure from scratch */
2480 fresh_leaks
= res
->leaks
;
2484 if (res
->corruptions
< old_res
.corruptions
) {
2485 res
->corruptions_fixed
+= old_res
.corruptions
- res
->corruptions
;
2487 if (res
->leaks
< old_res
.leaks
) {
2488 res
->leaks_fixed
+= old_res
.leaks
- res
->leaks
;
2490 res
->leaks
+= fresh_leaks
;
2493 fprintf(stderr
, "ERROR need to rebuild refcount structures\n");
2494 res
->check_errors
++;
2499 if (res
->leaks
|| res
->corruptions
) {
2500 *res
= pre_compare_res
;
2501 compare_refcounts(bs
, res
, fix
, &rebuild
, &highest_cluster
,
2502 refcount_table
, nb_clusters
);
2506 /* check OFLAG_COPIED */
2507 ret
= check_oflag_copied(bs
, res
, fix
);
2512 res
->image_end_offset
= (highest_cluster
+ 1) * s
->cluster_size
;
2516 g_free(refcount_table
);
2521 #define overlaps_with(ofs, sz) \
2522 ranges_overlap(offset, size, ofs, sz)
2525 * Checks if the given offset into the image file is actually free to use by
2526 * looking for overlaps with important metadata sections (L1/L2 tables etc.),
2527 * i.e. a sanity check without relying on the refcount tables.
2529 * The ign parameter specifies what checks not to perform (being a bitmask of
2530 * QCow2MetadataOverlap values), i.e., what sections to ignore.
2533 * - 0 if writing to this offset will not affect the mentioned metadata
2534 * - a positive QCow2MetadataOverlap value indicating one overlapping section
2535 * - a negative value (-errno) indicating an error while performing a check,
2536 * e.g. when bdrv_read failed on QCOW2_OL_INACTIVE_L2
2538 int qcow2_check_metadata_overlap(BlockDriverState
*bs
, int ign
, int64_t offset
,
2541 BDRVQcow2State
*s
= bs
->opaque
;
2542 int chk
= s
->overlap_check
& ~ign
;
2549 if (chk
& QCOW2_OL_MAIN_HEADER
) {
2550 if (offset
< s
->cluster_size
) {
2551 return QCOW2_OL_MAIN_HEADER
;
2555 /* align range to test to cluster boundaries */
2556 size
= align_offset(offset_into_cluster(s
, offset
) + size
, s
->cluster_size
);
2557 offset
= start_of_cluster(s
, offset
);
2559 if ((chk
& QCOW2_OL_ACTIVE_L1
) && s
->l1_size
) {
2560 if (overlaps_with(s
->l1_table_offset
, s
->l1_size
* sizeof(uint64_t))) {
2561 return QCOW2_OL_ACTIVE_L1
;
2565 if ((chk
& QCOW2_OL_REFCOUNT_TABLE
) && s
->refcount_table_size
) {
2566 if (overlaps_with(s
->refcount_table_offset
,
2567 s
->refcount_table_size
* sizeof(uint64_t))) {
2568 return QCOW2_OL_REFCOUNT_TABLE
;
2572 if ((chk
& QCOW2_OL_SNAPSHOT_TABLE
) && s
->snapshots_size
) {
2573 if (overlaps_with(s
->snapshots_offset
, s
->snapshots_size
)) {
2574 return QCOW2_OL_SNAPSHOT_TABLE
;
2578 if ((chk
& QCOW2_OL_INACTIVE_L1
) && s
->snapshots
) {
2579 for (i
= 0; i
< s
->nb_snapshots
; i
++) {
2580 if (s
->snapshots
[i
].l1_size
&&
2581 overlaps_with(s
->snapshots
[i
].l1_table_offset
,
2582 s
->snapshots
[i
].l1_size
* sizeof(uint64_t))) {
2583 return QCOW2_OL_INACTIVE_L1
;
2588 if ((chk
& QCOW2_OL_ACTIVE_L2
) && s
->l1_table
) {
2589 for (i
= 0; i
< s
->l1_size
; i
++) {
2590 if ((s
->l1_table
[i
] & L1E_OFFSET_MASK
) &&
2591 overlaps_with(s
->l1_table
[i
] & L1E_OFFSET_MASK
,
2593 return QCOW2_OL_ACTIVE_L2
;
2598 if ((chk
& QCOW2_OL_REFCOUNT_BLOCK
) && s
->refcount_table
) {
2599 unsigned last_entry
= s
->max_refcount_table_index
;
2600 assert(last_entry
< s
->refcount_table_size
);
2601 assert(last_entry
+ 1 == s
->refcount_table_size
||
2602 (s
->refcount_table
[last_entry
+ 1] & REFT_OFFSET_MASK
) == 0);
2603 for (i
= 0; i
<= last_entry
; i
++) {
2604 if ((s
->refcount_table
[i
] & REFT_OFFSET_MASK
) &&
2605 overlaps_with(s
->refcount_table
[i
] & REFT_OFFSET_MASK
,
2607 return QCOW2_OL_REFCOUNT_BLOCK
;
2612 if ((chk
& QCOW2_OL_INACTIVE_L2
) && s
->snapshots
) {
2613 for (i
= 0; i
< s
->nb_snapshots
; i
++) {
2614 uint64_t l1_ofs
= s
->snapshots
[i
].l1_table_offset
;
2615 uint32_t l1_sz
= s
->snapshots
[i
].l1_size
;
2616 uint64_t l1_sz2
= l1_sz
* sizeof(uint64_t);
2617 uint64_t *l1
= g_try_malloc(l1_sz2
);
2620 if (l1_sz2
&& l1
== NULL
) {
2624 ret
= bdrv_pread(bs
->file
, l1_ofs
, l1
, l1_sz2
);
2630 for (j
= 0; j
< l1_sz
; j
++) {
2631 uint64_t l2_ofs
= be64_to_cpu(l1
[j
]) & L1E_OFFSET_MASK
;
2632 if (l2_ofs
&& overlaps_with(l2_ofs
, s
->cluster_size
)) {
2634 return QCOW2_OL_INACTIVE_L2
;
2645 static const char *metadata_ol_names
[] = {
2646 [QCOW2_OL_MAIN_HEADER_BITNR
] = "qcow2_header",
2647 [QCOW2_OL_ACTIVE_L1_BITNR
] = "active L1 table",
2648 [QCOW2_OL_ACTIVE_L2_BITNR
] = "active L2 table",
2649 [QCOW2_OL_REFCOUNT_TABLE_BITNR
] = "refcount table",
2650 [QCOW2_OL_REFCOUNT_BLOCK_BITNR
] = "refcount block",
2651 [QCOW2_OL_SNAPSHOT_TABLE_BITNR
] = "snapshot table",
2652 [QCOW2_OL_INACTIVE_L1_BITNR
] = "inactive L1 table",
2653 [QCOW2_OL_INACTIVE_L2_BITNR
] = "inactive L2 table",
2657 * First performs a check for metadata overlaps (through
2658 * qcow2_check_metadata_overlap); if that fails with a negative value (error
2659 * while performing a check), that value is returned. If an impending overlap
2660 * is detected, the BDS will be made unusable, the qcow2 file marked corrupt
2661 * and -EIO returned.
2663 * Returns 0 if there were neither overlaps nor errors while checking for
2664 * overlaps; or a negative value (-errno) on error.
2666 int qcow2_pre_write_overlap_check(BlockDriverState
*bs
, int ign
, int64_t offset
,
2669 int ret
= qcow2_check_metadata_overlap(bs
, ign
, offset
, size
);
2673 } else if (ret
> 0) {
2674 int metadata_ol_bitnr
= ctz32(ret
);
2675 assert(metadata_ol_bitnr
< QCOW2_OL_MAX_BITNR
);
2677 qcow2_signal_corruption(bs
, true, offset
, size
, "Preventing invalid "
2678 "write on metadata (overlaps with %s)",
2679 metadata_ol_names
[metadata_ol_bitnr
]);
2686 /* A pointer to a function of this type is given to walk_over_reftable(). That
2687 * function will create refblocks and pass them to a RefblockFinishOp once they
2688 * are completed (@refblock). @refblock_empty is set if the refblock is
2691 * Along with the refblock, a corresponding reftable entry is passed, in the
2692 * reftable @reftable (which may be reallocated) at @reftable_index.
2694 * @allocated should be set to true if a new cluster has been allocated.
2696 typedef int (RefblockFinishOp
)(BlockDriverState
*bs
, uint64_t **reftable
,
2697 uint64_t reftable_index
, uint64_t *reftable_size
,
2698 void *refblock
, bool refblock_empty
,
2699 bool *allocated
, Error
**errp
);
2702 * This "operation" for walk_over_reftable() allocates the refblock on disk (if
2703 * it is not empty) and inserts its offset into the new reftable. The size of
2704 * this new reftable is increased as required.
2706 static int alloc_refblock(BlockDriverState
*bs
, uint64_t **reftable
,
2707 uint64_t reftable_index
, uint64_t *reftable_size
,
2708 void *refblock
, bool refblock_empty
, bool *allocated
,
2711 BDRVQcow2State
*s
= bs
->opaque
;
2714 if (!refblock_empty
&& reftable_index
>= *reftable_size
) {
2715 uint64_t *new_reftable
;
2716 uint64_t new_reftable_size
;
2718 new_reftable_size
= ROUND_UP(reftable_index
+ 1,
2719 s
->cluster_size
/ sizeof(uint64_t));
2720 if (new_reftable_size
> QCOW_MAX_REFTABLE_SIZE
/ sizeof(uint64_t)) {
2722 "This operation would make the refcount table grow "
2723 "beyond the maximum size supported by QEMU, aborting");
2727 new_reftable
= g_try_realloc(*reftable
, new_reftable_size
*
2729 if (!new_reftable
) {
2730 error_setg(errp
, "Failed to increase reftable buffer size");
2734 memset(new_reftable
+ *reftable_size
, 0,
2735 (new_reftable_size
- *reftable_size
) * sizeof(uint64_t));
2737 *reftable
= new_reftable
;
2738 *reftable_size
= new_reftable_size
;
2741 if (!refblock_empty
&& !(*reftable
)[reftable_index
]) {
2742 offset
= qcow2_alloc_clusters(bs
, s
->cluster_size
);
2744 error_setg_errno(errp
, -offset
, "Failed to allocate refblock");
2747 (*reftable
)[reftable_index
] = offset
;
2755 * This "operation" for walk_over_reftable() writes the refblock to disk at the
2756 * offset specified by the new reftable's entry. It does not modify the new
2757 * reftable or change any refcounts.
2759 static int flush_refblock(BlockDriverState
*bs
, uint64_t **reftable
,
2760 uint64_t reftable_index
, uint64_t *reftable_size
,
2761 void *refblock
, bool refblock_empty
, bool *allocated
,
2764 BDRVQcow2State
*s
= bs
->opaque
;
2768 if (reftable_index
< *reftable_size
&& (*reftable
)[reftable_index
]) {
2769 offset
= (*reftable
)[reftable_index
];
2771 ret
= qcow2_pre_write_overlap_check(bs
, 0, offset
, s
->cluster_size
);
2773 error_setg_errno(errp
, -ret
, "Overlap check failed");
2777 ret
= bdrv_pwrite(bs
->file
, offset
, refblock
, s
->cluster_size
);
2779 error_setg_errno(errp
, -ret
, "Failed to write refblock");
2783 assert(refblock_empty
);
2790 * This function walks over the existing reftable and every referenced refblock;
2791 * if @new_set_refcount is non-NULL, it is called for every refcount entry to
2792 * create an equal new entry in the passed @new_refblock. Once that
2793 * @new_refblock is completely filled, @operation will be called.
2795 * @status_cb and @cb_opaque are used for the amend operation's status callback.
2796 * @index is the index of the walk_over_reftable() calls and @total is the total
2797 * number of walk_over_reftable() calls per amend operation. Both are used for
2798 * calculating the parameters for the status callback.
2800 * @allocated is set to true if a new cluster has been allocated.
2802 static int walk_over_reftable(BlockDriverState
*bs
, uint64_t **new_reftable
,
2803 uint64_t *new_reftable_index
,
2804 uint64_t *new_reftable_size
,
2805 void *new_refblock
, int new_refblock_size
,
2806 int new_refcount_bits
,
2807 RefblockFinishOp
*operation
, bool *allocated
,
2808 Qcow2SetRefcountFunc
*new_set_refcount
,
2809 BlockDriverAmendStatusCB
*status_cb
,
2810 void *cb_opaque
, int index
, int total
,
2813 BDRVQcow2State
*s
= bs
->opaque
;
2814 uint64_t reftable_index
;
2815 bool new_refblock_empty
= true;
2817 int new_refblock_index
= 0;
2820 for (reftable_index
= 0; reftable_index
< s
->refcount_table_size
;
2823 uint64_t refblock_offset
= s
->refcount_table
[reftable_index
]
2826 status_cb(bs
, (uint64_t)index
* s
->refcount_table_size
+ reftable_index
,
2827 (uint64_t)total
* s
->refcount_table_size
, cb_opaque
);
2829 if (refblock_offset
) {
2832 if (offset_into_cluster(s
, refblock_offset
)) {
2833 qcow2_signal_corruption(bs
, true, -1, -1, "Refblock offset %#"
2834 PRIx64
" unaligned (reftable index: %#"
2835 PRIx64
")", refblock_offset
,
2838 "Image is corrupt (unaligned refblock offset)");
2842 ret
= qcow2_cache_get(bs
, s
->refcount_block_cache
, refblock_offset
,
2845 error_setg_errno(errp
, -ret
, "Failed to retrieve refblock");
2849 for (refblock_index
= 0; refblock_index
< s
->refcount_block_size
;
2854 if (new_refblock_index
>= new_refblock_size
) {
2855 /* new_refblock is now complete */
2856 ret
= operation(bs
, new_reftable
, *new_reftable_index
,
2857 new_reftable_size
, new_refblock
,
2858 new_refblock_empty
, allocated
, errp
);
2860 qcow2_cache_put(s
->refcount_block_cache
, &refblock
);
2864 (*new_reftable_index
)++;
2865 new_refblock_index
= 0;
2866 new_refblock_empty
= true;
2869 refcount
= s
->get_refcount(refblock
, refblock_index
);
2870 if (new_refcount_bits
< 64 && refcount
>> new_refcount_bits
) {
2873 qcow2_cache_put(s
->refcount_block_cache
, &refblock
);
2875 offset
= ((reftable_index
<< s
->refcount_block_bits
)
2876 + refblock_index
) << s
->cluster_bits
;
2878 error_setg(errp
, "Cannot decrease refcount entry width to "
2879 "%i bits: Cluster at offset %#" PRIx64
" has a "
2880 "refcount of %" PRIu64
, new_refcount_bits
,
2885 if (new_set_refcount
) {
2886 new_set_refcount(new_refblock
, new_refblock_index
++,
2889 new_refblock_index
++;
2891 new_refblock_empty
= new_refblock_empty
&& refcount
== 0;
2894 qcow2_cache_put(s
->refcount_block_cache
, &refblock
);
2896 /* No refblock means every refcount is 0 */
2897 for (refblock_index
= 0; refblock_index
< s
->refcount_block_size
;
2900 if (new_refblock_index
>= new_refblock_size
) {
2901 /* new_refblock is now complete */
2902 ret
= operation(bs
, new_reftable
, *new_reftable_index
,
2903 new_reftable_size
, new_refblock
,
2904 new_refblock_empty
, allocated
, errp
);
2909 (*new_reftable_index
)++;
2910 new_refblock_index
= 0;
2911 new_refblock_empty
= true;
2914 if (new_set_refcount
) {
2915 new_set_refcount(new_refblock
, new_refblock_index
++, 0);
2917 new_refblock_index
++;
2923 if (new_refblock_index
> 0) {
2924 /* Complete the potentially existing partially filled final refblock */
2925 if (new_set_refcount
) {
2926 for (; new_refblock_index
< new_refblock_size
;
2927 new_refblock_index
++)
2929 new_set_refcount(new_refblock
, new_refblock_index
, 0);
2933 ret
= operation(bs
, new_reftable
, *new_reftable_index
,
2934 new_reftable_size
, new_refblock
, new_refblock_empty
,
2940 (*new_reftable_index
)++;
2943 status_cb(bs
, (uint64_t)(index
+ 1) * s
->refcount_table_size
,
2944 (uint64_t)total
* s
->refcount_table_size
, cb_opaque
);
2949 int qcow2_change_refcount_order(BlockDriverState
*bs
, int refcount_order
,
2950 BlockDriverAmendStatusCB
*status_cb
,
2951 void *cb_opaque
, Error
**errp
)
2953 BDRVQcow2State
*s
= bs
->opaque
;
2954 Qcow2GetRefcountFunc
*new_get_refcount
;
2955 Qcow2SetRefcountFunc
*new_set_refcount
;
2956 void *new_refblock
= qemu_blockalign(bs
->file
->bs
, s
->cluster_size
);
2957 uint64_t *new_reftable
= NULL
, new_reftable_size
= 0;
2958 uint64_t *old_reftable
, old_reftable_size
, old_reftable_offset
;
2959 uint64_t new_reftable_index
= 0;
2961 int64_t new_reftable_offset
= 0, allocated_reftable_size
= 0;
2962 int new_refblock_size
, new_refcount_bits
= 1 << refcount_order
;
2963 int old_refcount_order
;
2966 bool new_allocation
;
2968 assert(s
->qcow_version
>= 3);
2969 assert(refcount_order
>= 0 && refcount_order
<= 6);
2971 /* see qcow2_open() */
2972 new_refblock_size
= 1 << (s
->cluster_bits
- (refcount_order
- 3));
2974 new_get_refcount
= get_refcount_funcs
[refcount_order
];
2975 new_set_refcount
= set_refcount_funcs
[refcount_order
];
2981 new_allocation
= false;
2983 /* At least we have to do this walk and the one which writes the
2984 * refblocks; also, at least we have to do this loop here at least
2985 * twice (normally), first to do the allocations, and second to
2986 * determine that everything is correctly allocated, this then makes
2987 * three walks in total */
2988 total_walks
= MAX(walk_index
+ 2, 3);
2990 /* First, allocate the structures so they are present in the refcount
2992 ret
= walk_over_reftable(bs
, &new_reftable
, &new_reftable_index
,
2993 &new_reftable_size
, NULL
, new_refblock_size
,
2994 new_refcount_bits
, &alloc_refblock
,
2995 &new_allocation
, NULL
, status_cb
, cb_opaque
,
2996 walk_index
++, total_walks
, errp
);
3001 new_reftable_index
= 0;
3003 if (new_allocation
) {
3004 if (new_reftable_offset
) {
3005 qcow2_free_clusters(bs
, new_reftable_offset
,
3006 allocated_reftable_size
* sizeof(uint64_t),
3007 QCOW2_DISCARD_NEVER
);
3010 new_reftable_offset
= qcow2_alloc_clusters(bs
, new_reftable_size
*
3012 if (new_reftable_offset
< 0) {
3013 error_setg_errno(errp
, -new_reftable_offset
,
3014 "Failed to allocate the new reftable");
3015 ret
= new_reftable_offset
;
3018 allocated_reftable_size
= new_reftable_size
;
3020 } while (new_allocation
);
3022 /* Second, write the new refblocks */
3023 ret
= walk_over_reftable(bs
, &new_reftable
, &new_reftable_index
,
3024 &new_reftable_size
, new_refblock
,
3025 new_refblock_size
, new_refcount_bits
,
3026 &flush_refblock
, &new_allocation
, new_set_refcount
,
3027 status_cb
, cb_opaque
, walk_index
, walk_index
+ 1,
3032 assert(!new_allocation
);
3035 /* Write the new reftable */
3036 ret
= qcow2_pre_write_overlap_check(bs
, 0, new_reftable_offset
,
3037 new_reftable_size
* sizeof(uint64_t));
3039 error_setg_errno(errp
, -ret
, "Overlap check failed");
3043 for (i
= 0; i
< new_reftable_size
; i
++) {
3044 cpu_to_be64s(&new_reftable
[i
]);
3047 ret
= bdrv_pwrite(bs
->file
, new_reftable_offset
, new_reftable
,
3048 new_reftable_size
* sizeof(uint64_t));
3050 for (i
= 0; i
< new_reftable_size
; i
++) {
3051 be64_to_cpus(&new_reftable
[i
]);
3055 error_setg_errno(errp
, -ret
, "Failed to write the new reftable");
3060 /* Empty the refcount cache */
3061 ret
= qcow2_cache_flush(bs
, s
->refcount_block_cache
);
3063 error_setg_errno(errp
, -ret
, "Failed to flush the refblock cache");
3067 /* Update the image header to point to the new reftable; this only updates
3068 * the fields which are relevant to qcow2_update_header(); other fields
3069 * such as s->refcount_table or s->refcount_bits stay stale for now
3070 * (because we have to restore everything if qcow2_update_header() fails) */
3071 old_refcount_order
= s
->refcount_order
;
3072 old_reftable_size
= s
->refcount_table_size
;
3073 old_reftable_offset
= s
->refcount_table_offset
;
3075 s
->refcount_order
= refcount_order
;
3076 s
->refcount_table_size
= new_reftable_size
;
3077 s
->refcount_table_offset
= new_reftable_offset
;
3079 ret
= qcow2_update_header(bs
);
3081 s
->refcount_order
= old_refcount_order
;
3082 s
->refcount_table_size
= old_reftable_size
;
3083 s
->refcount_table_offset
= old_reftable_offset
;
3084 error_setg_errno(errp
, -ret
, "Failed to update the qcow2 header");
3088 /* Now update the rest of the in-memory information */
3089 old_reftable
= s
->refcount_table
;
3090 s
->refcount_table
= new_reftable
;
3091 update_max_refcount_table_index(s
);
3093 s
->refcount_bits
= 1 << refcount_order
;
3094 s
->refcount_max
= UINT64_C(1) << (s
->refcount_bits
- 1);
3095 s
->refcount_max
+= s
->refcount_max
- 1;
3097 s
->refcount_block_bits
= s
->cluster_bits
- (refcount_order
- 3);
3098 s
->refcount_block_size
= 1 << s
->refcount_block_bits
;
3100 s
->get_refcount
= new_get_refcount
;
3101 s
->set_refcount
= new_set_refcount
;
3103 /* For cleaning up all old refblocks and the old reftable below the "done"
3105 new_reftable
= old_reftable
;
3106 new_reftable_size
= old_reftable_size
;
3107 new_reftable_offset
= old_reftable_offset
;
3111 /* On success, new_reftable actually points to the old reftable (and
3112 * new_reftable_size is the old reftable's size); but that is just
3114 for (i
= 0; i
< new_reftable_size
; i
++) {
3115 uint64_t offset
= new_reftable
[i
] & REFT_OFFSET_MASK
;
3117 qcow2_free_clusters(bs
, offset
, s
->cluster_size
,
3118 QCOW2_DISCARD_OTHER
);
3121 g_free(new_reftable
);
3123 if (new_reftable_offset
> 0) {
3124 qcow2_free_clusters(bs
, new_reftable_offset
,
3125 new_reftable_size
* sizeof(uint64_t),
3126 QCOW2_DISCARD_OTHER
);
3130 qemu_vfree(new_refblock
);
3134 static int64_t get_refblock_offset(BlockDriverState
*bs
, uint64_t offset
)
3136 BDRVQcow2State
*s
= bs
->opaque
;
3137 uint32_t index
= offset_to_reftable_index(s
, offset
);
3138 int64_t covering_refblock_offset
= 0;
3140 if (index
< s
->refcount_table_size
) {
3141 covering_refblock_offset
= s
->refcount_table
[index
] & REFT_OFFSET_MASK
;
3143 if (!covering_refblock_offset
) {
3144 qcow2_signal_corruption(bs
, true, -1, -1, "Refblock at %#" PRIx64
" is "
3145 "not covered by the refcount structures",
3150 return covering_refblock_offset
;
3153 static int qcow2_discard_refcount_block(BlockDriverState
*bs
,
3154 uint64_t discard_block_offs
)
3156 BDRVQcow2State
*s
= bs
->opaque
;
3157 int64_t refblock_offs
;
3158 uint64_t cluster_index
= discard_block_offs
>> s
->cluster_bits
;
3159 uint32_t block_index
= cluster_index
& (s
->refcount_block_size
- 1);
3163 refblock_offs
= get_refblock_offset(bs
, discard_block_offs
);
3164 if (refblock_offs
< 0) {
3165 return refblock_offs
;
3168 assert(discard_block_offs
!= 0);
3170 ret
= qcow2_cache_get(bs
, s
->refcount_block_cache
, refblock_offs
,
3176 if (s
->get_refcount(refblock
, block_index
) != 1) {
3177 qcow2_signal_corruption(bs
, true, -1, -1, "Invalid refcount:"
3178 " refblock offset %#" PRIx64
3179 ", reftable index %u"
3180 ", block offset %#" PRIx64
3181 ", refcount %#" PRIx64
,
3183 offset_to_reftable_index(s
, discard_block_offs
),
3185 s
->get_refcount(refblock
, block_index
));
3186 qcow2_cache_put(s
->refcount_block_cache
, &refblock
);
3189 s
->set_refcount(refblock
, block_index
, 0);
3191 qcow2_cache_entry_mark_dirty(s
->refcount_block_cache
, refblock
);
3193 qcow2_cache_put(s
->refcount_block_cache
, &refblock
);
3195 if (cluster_index
< s
->free_cluster_index
) {
3196 s
->free_cluster_index
= cluster_index
;
3199 refblock
= qcow2_cache_is_table_offset(s
->refcount_block_cache
,
3200 discard_block_offs
);
3202 /* discard refblock from the cache if refblock is cached */
3203 qcow2_cache_discard(s
->refcount_block_cache
, refblock
);
3205 update_refcount_discard(bs
, discard_block_offs
, s
->cluster_size
);
3210 int qcow2_shrink_reftable(BlockDriverState
*bs
)
3212 BDRVQcow2State
*s
= bs
->opaque
;
3213 uint64_t *reftable_tmp
=
3214 g_malloc(s
->refcount_table_size
* sizeof(uint64_t));
3217 for (i
= 0; i
< s
->refcount_table_size
; i
++) {
3218 int64_t refblock_offs
= s
->refcount_table
[i
] & REFT_OFFSET_MASK
;
3222 if (refblock_offs
== 0) {
3223 reftable_tmp
[i
] = 0;
3226 ret
= qcow2_cache_get(bs
, s
->refcount_block_cache
, refblock_offs
,
3232 /* the refblock has own reference */
3233 if (i
== offset_to_reftable_index(s
, refblock_offs
)) {
3234 uint64_t block_index
= (refblock_offs
>> s
->cluster_bits
) &
3235 (s
->refcount_block_size
- 1);
3236 uint64_t refcount
= s
->get_refcount(refblock
, block_index
);
3238 s
->set_refcount(refblock
, block_index
, 0);
3240 unused_block
= buffer_is_zero(refblock
, s
->cluster_size
);
3242 s
->set_refcount(refblock
, block_index
, refcount
);
3244 unused_block
= buffer_is_zero(refblock
, s
->cluster_size
);
3246 qcow2_cache_put(s
->refcount_block_cache
, &refblock
);
3248 reftable_tmp
[i
] = unused_block
? 0 : cpu_to_be64(s
->refcount_table
[i
]);
3251 ret
= bdrv_pwrite_sync(bs
->file
, s
->refcount_table_offset
, reftable_tmp
,
3252 s
->refcount_table_size
* sizeof(uint64_t));
3254 * If the write in the reftable failed the image may contain a partially
3255 * overwritten reftable. In this case it would be better to clear the
3256 * reftable in memory to avoid possible image corruption.
3258 for (i
= 0; i
< s
->refcount_table_size
; i
++) {
3259 if (s
->refcount_table
[i
] && !reftable_tmp
[i
]) {
3261 ret
= qcow2_discard_refcount_block(bs
, s
->refcount_table
[i
] &
3264 s
->refcount_table
[i
] = 0;
3268 if (!s
->cache_discards
) {
3269 qcow2_process_discards(bs
, ret
);
3273 g_free(reftable_tmp
);
3277 int64_t qcow2_get_last_cluster(BlockDriverState
*bs
, int64_t size
)
3279 BDRVQcow2State
*s
= bs
->opaque
;
3282 for (i
= size_to_clusters(s
, size
) - 1; i
>= 0; i
--) {
3284 int ret
= qcow2_get_refcount(bs
, i
, &refcount
);
3286 fprintf(stderr
, "Can't get refcount for cluster %" PRId64
": %s\n",
3294 qcow2_signal_corruption(bs
, true, -1, -1,
3295 "There are no references in the refcount table.");