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
24 #include "qemu-common.h"
25 #include "block/block_int.h"
26 #include "qemu/module.h"
29 #include "block/qcow2.h"
30 #include "qemu/error-report.h"
31 #include "qapi/qmp/qerror.h"
32 #include "qapi/qmp/qbool.h"
33 #include "qapi/util.h"
34 #include "qapi/qmp/types.h"
35 #include "qapi-event.h"
37 #include "qemu/option_int.h"
40 Differences with QCOW:
42 - Support for multiple incremental snapshots.
43 - Memory management by reference counts.
44 - Clusters which have a reference count of one have the bit
45 QCOW_OFLAG_COPIED to optimize write performance.
46 - Size of compressed clusters is stored in sectors to reduce bit usage
47 in the cluster offsets.
48 - Support for storing additional data (such as the VM state) in the
50 - If a backing store is used, the cluster size is not constrained
51 (could be backported to QCOW).
52 - L2 tables have always a size of one cluster.
59 } QEMU_PACKED QCowExtension
;
61 #define QCOW2_EXT_MAGIC_END 0
62 #define QCOW2_EXT_MAGIC_BACKING_FORMAT 0xE2792ACA
63 #define QCOW2_EXT_MAGIC_FEATURE_TABLE 0x6803f857
65 static int qcow2_probe(const uint8_t *buf
, int buf_size
, const char *filename
)
67 const QCowHeader
*cow_header
= (const void *)buf
;
69 if (buf_size
>= sizeof(QCowHeader
) &&
70 be32_to_cpu(cow_header
->magic
) == QCOW_MAGIC
&&
71 be32_to_cpu(cow_header
->version
) >= 2)
79 * read qcow2 extension and fill bs
80 * start reading from start_offset
81 * finish reading upon magic of value 0 or when end_offset reached
82 * unknown magic is skipped (future extension this version knows nothing about)
83 * return 0 upon success, non-0 otherwise
85 static int qcow2_read_extensions(BlockDriverState
*bs
, uint64_t start_offset
,
86 uint64_t end_offset
, void **p_feature_table
,
89 BDRVQcowState
*s
= bs
->opaque
;
95 printf("qcow2_read_extensions: start=%ld end=%ld\n", start_offset
, end_offset
);
97 offset
= start_offset
;
98 while (offset
< end_offset
) {
102 if (offset
> s
->cluster_size
)
103 printf("qcow2_read_extension: suspicious offset %lu\n", offset
);
105 printf("attempting to read extended header in offset %lu\n", offset
);
108 ret
= bdrv_pread(bs
->file
, offset
, &ext
, sizeof(ext
));
110 error_setg_errno(errp
, -ret
, "qcow2_read_extension: ERROR: "
111 "pread fail from offset %" PRIu64
, offset
);
114 be32_to_cpus(&ext
.magic
);
115 be32_to_cpus(&ext
.len
);
116 offset
+= sizeof(ext
);
118 printf("ext.magic = 0x%x\n", ext
.magic
);
120 if (offset
> end_offset
|| ext
.len
> end_offset
- offset
) {
121 error_setg(errp
, "Header extension too large");
126 case QCOW2_EXT_MAGIC_END
:
129 case QCOW2_EXT_MAGIC_BACKING_FORMAT
:
130 if (ext
.len
>= sizeof(bs
->backing_format
)) {
131 error_setg(errp
, "ERROR: ext_backing_format: len=%" PRIu32
132 " too large (>=%zu)", ext
.len
,
133 sizeof(bs
->backing_format
));
136 ret
= bdrv_pread(bs
->file
, offset
, bs
->backing_format
, ext
.len
);
138 error_setg_errno(errp
, -ret
, "ERROR: ext_backing_format: "
139 "Could not read format name");
142 bs
->backing_format
[ext
.len
] = '\0';
144 printf("Qcow2: Got format extension %s\n", bs
->backing_format
);
148 case QCOW2_EXT_MAGIC_FEATURE_TABLE
:
149 if (p_feature_table
!= NULL
) {
150 void* feature_table
= g_malloc0(ext
.len
+ 2 * sizeof(Qcow2Feature
));
151 ret
= bdrv_pread(bs
->file
, offset
, feature_table
, ext
.len
);
153 error_setg_errno(errp
, -ret
, "ERROR: ext_feature_table: "
154 "Could not read table");
158 *p_feature_table
= feature_table
;
163 /* unknown magic - save it in case we need to rewrite the header */
165 Qcow2UnknownHeaderExtension
*uext
;
167 uext
= g_malloc0(sizeof(*uext
) + ext
.len
);
168 uext
->magic
= ext
.magic
;
170 QLIST_INSERT_HEAD(&s
->unknown_header_ext
, uext
, next
);
172 ret
= bdrv_pread(bs
->file
, offset
, uext
->data
, uext
->len
);
174 error_setg_errno(errp
, -ret
, "ERROR: unknown extension: "
175 "Could not read data");
182 offset
+= ((ext
.len
+ 7) & ~7);
188 static void cleanup_unknown_header_ext(BlockDriverState
*bs
)
190 BDRVQcowState
*s
= bs
->opaque
;
191 Qcow2UnknownHeaderExtension
*uext
, *next
;
193 QLIST_FOREACH_SAFE(uext
, &s
->unknown_header_ext
, next
, next
) {
194 QLIST_REMOVE(uext
, next
);
199 static void GCC_FMT_ATTR(3, 4) report_unsupported(BlockDriverState
*bs
,
200 Error
**errp
, const char *fmt
, ...)
206 vsnprintf(msg
, sizeof(msg
), fmt
, ap
);
209 error_set(errp
, QERR_UNKNOWN_BLOCK_FORMAT_FEATURE
,
210 bdrv_get_device_name(bs
), "qcow2", msg
);
213 static void report_unsupported_feature(BlockDriverState
*bs
,
214 Error
**errp
, Qcow2Feature
*table
, uint64_t mask
)
216 char *features
= g_strdup("");
219 while (table
&& table
->name
[0] != '\0') {
220 if (table
->type
== QCOW2_FEAT_TYPE_INCOMPATIBLE
) {
221 if (mask
& (1ULL << table
->bit
)) {
223 features
= g_strdup_printf("%s%s%.46s", old
, *old
? ", " : "",
226 mask
&= ~(1ULL << table
->bit
);
234 features
= g_strdup_printf("%s%sUnknown incompatible feature: %" PRIx64
,
235 old
, *old
? ", " : "", mask
);
239 report_unsupported(bs
, errp
, "%s", features
);
244 * Sets the dirty bit and flushes afterwards if necessary.
246 * The incompatible_features bit is only set if the image file header was
247 * updated successfully. Therefore it is not required to check the return
248 * value of this function.
250 int qcow2_mark_dirty(BlockDriverState
*bs
)
252 BDRVQcowState
*s
= bs
->opaque
;
256 assert(s
->qcow_version
>= 3);
258 if (s
->incompatible_features
& QCOW2_INCOMPAT_DIRTY
) {
259 return 0; /* already dirty */
262 val
= cpu_to_be64(s
->incompatible_features
| QCOW2_INCOMPAT_DIRTY
);
263 ret
= bdrv_pwrite(bs
->file
, offsetof(QCowHeader
, incompatible_features
),
268 ret
= bdrv_flush(bs
->file
);
273 /* Only treat image as dirty if the header was updated successfully */
274 s
->incompatible_features
|= QCOW2_INCOMPAT_DIRTY
;
279 * Clears the dirty bit and flushes before if necessary. Only call this
280 * function when there are no pending requests, it does not guard against
281 * concurrent requests dirtying the image.
283 static int qcow2_mark_clean(BlockDriverState
*bs
)
285 BDRVQcowState
*s
= bs
->opaque
;
287 if (s
->incompatible_features
& QCOW2_INCOMPAT_DIRTY
) {
290 s
->incompatible_features
&= ~QCOW2_INCOMPAT_DIRTY
;
292 ret
= bdrv_flush(bs
);
297 return qcow2_update_header(bs
);
303 * Marks the image as corrupt.
305 int qcow2_mark_corrupt(BlockDriverState
*bs
)
307 BDRVQcowState
*s
= bs
->opaque
;
309 s
->incompatible_features
|= QCOW2_INCOMPAT_CORRUPT
;
310 return qcow2_update_header(bs
);
314 * Marks the image as consistent, i.e., unsets the corrupt bit, and flushes
315 * before if necessary.
317 int qcow2_mark_consistent(BlockDriverState
*bs
)
319 BDRVQcowState
*s
= bs
->opaque
;
321 if (s
->incompatible_features
& QCOW2_INCOMPAT_CORRUPT
) {
322 int ret
= bdrv_flush(bs
);
327 s
->incompatible_features
&= ~QCOW2_INCOMPAT_CORRUPT
;
328 return qcow2_update_header(bs
);
333 static int qcow2_check(BlockDriverState
*bs
, BdrvCheckResult
*result
,
336 int ret
= qcow2_check_refcounts(bs
, result
, fix
);
341 if (fix
&& result
->check_errors
== 0 && result
->corruptions
== 0) {
342 ret
= qcow2_mark_clean(bs
);
346 return qcow2_mark_consistent(bs
);
351 static int validate_table_offset(BlockDriverState
*bs
, uint64_t offset
,
352 uint64_t entries
, size_t entry_len
)
354 BDRVQcowState
*s
= bs
->opaque
;
357 /* Use signed INT64_MAX as the maximum even for uint64_t header fields,
358 * because values will be passed to qemu functions taking int64_t. */
359 if (entries
> INT64_MAX
/ entry_len
) {
363 size
= entries
* entry_len
;
365 if (INT64_MAX
- size
< offset
) {
369 /* Tables must be cluster aligned */
370 if (offset
& (s
->cluster_size
- 1)) {
377 static QemuOptsList qcow2_runtime_opts
= {
379 .head
= QTAILQ_HEAD_INITIALIZER(qcow2_runtime_opts
.head
),
382 .name
= QCOW2_OPT_LAZY_REFCOUNTS
,
383 .type
= QEMU_OPT_BOOL
,
384 .help
= "Postpone refcount updates",
387 .name
= QCOW2_OPT_DISCARD_REQUEST
,
388 .type
= QEMU_OPT_BOOL
,
389 .help
= "Pass guest discard requests to the layer below",
392 .name
= QCOW2_OPT_DISCARD_SNAPSHOT
,
393 .type
= QEMU_OPT_BOOL
,
394 .help
= "Generate discard requests when snapshot related space "
398 .name
= QCOW2_OPT_DISCARD_OTHER
,
399 .type
= QEMU_OPT_BOOL
,
400 .help
= "Generate discard requests when other clusters are freed",
403 .name
= QCOW2_OPT_OVERLAP
,
404 .type
= QEMU_OPT_STRING
,
405 .help
= "Selects which overlap checks to perform from a range of "
406 "templates (none, constant, cached, all)",
409 .name
= QCOW2_OPT_OVERLAP_TEMPLATE
,
410 .type
= QEMU_OPT_STRING
,
411 .help
= "Selects which overlap checks to perform from a range of "
412 "templates (none, constant, cached, all)",
415 .name
= QCOW2_OPT_OVERLAP_MAIN_HEADER
,
416 .type
= QEMU_OPT_BOOL
,
417 .help
= "Check for unintended writes into the main qcow2 header",
420 .name
= QCOW2_OPT_OVERLAP_ACTIVE_L1
,
421 .type
= QEMU_OPT_BOOL
,
422 .help
= "Check for unintended writes into the active L1 table",
425 .name
= QCOW2_OPT_OVERLAP_ACTIVE_L2
,
426 .type
= QEMU_OPT_BOOL
,
427 .help
= "Check for unintended writes into an active L2 table",
430 .name
= QCOW2_OPT_OVERLAP_REFCOUNT_TABLE
,
431 .type
= QEMU_OPT_BOOL
,
432 .help
= "Check for unintended writes into the refcount table",
435 .name
= QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK
,
436 .type
= QEMU_OPT_BOOL
,
437 .help
= "Check for unintended writes into a refcount block",
440 .name
= QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE
,
441 .type
= QEMU_OPT_BOOL
,
442 .help
= "Check for unintended writes into the snapshot table",
445 .name
= QCOW2_OPT_OVERLAP_INACTIVE_L1
,
446 .type
= QEMU_OPT_BOOL
,
447 .help
= "Check for unintended writes into an inactive L1 table",
450 .name
= QCOW2_OPT_OVERLAP_INACTIVE_L2
,
451 .type
= QEMU_OPT_BOOL
,
452 .help
= "Check for unintended writes into an inactive L2 table",
455 .name
= QCOW2_OPT_CACHE_SIZE
,
456 .type
= QEMU_OPT_SIZE
,
457 .help
= "Maximum combined metadata (L2 tables and refcount blocks) "
461 .name
= QCOW2_OPT_L2_CACHE_SIZE
,
462 .type
= QEMU_OPT_SIZE
,
463 .help
= "Maximum L2 table cache size",
466 .name
= QCOW2_OPT_REFCOUNT_CACHE_SIZE
,
467 .type
= QEMU_OPT_SIZE
,
468 .help
= "Maximum refcount block cache size",
470 { /* end of list */ }
474 static const char *overlap_bool_option_names
[QCOW2_OL_MAX_BITNR
] = {
475 [QCOW2_OL_MAIN_HEADER_BITNR
] = QCOW2_OPT_OVERLAP_MAIN_HEADER
,
476 [QCOW2_OL_ACTIVE_L1_BITNR
] = QCOW2_OPT_OVERLAP_ACTIVE_L1
,
477 [QCOW2_OL_ACTIVE_L2_BITNR
] = QCOW2_OPT_OVERLAP_ACTIVE_L2
,
478 [QCOW2_OL_REFCOUNT_TABLE_BITNR
] = QCOW2_OPT_OVERLAP_REFCOUNT_TABLE
,
479 [QCOW2_OL_REFCOUNT_BLOCK_BITNR
] = QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK
,
480 [QCOW2_OL_SNAPSHOT_TABLE_BITNR
] = QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE
,
481 [QCOW2_OL_INACTIVE_L1_BITNR
] = QCOW2_OPT_OVERLAP_INACTIVE_L1
,
482 [QCOW2_OL_INACTIVE_L2_BITNR
] = QCOW2_OPT_OVERLAP_INACTIVE_L2
,
485 static void read_cache_sizes(QemuOpts
*opts
, uint64_t *l2_cache_size
,
486 uint64_t *refcount_cache_size
, Error
**errp
)
488 uint64_t combined_cache_size
;
489 bool l2_cache_size_set
, refcount_cache_size_set
, combined_cache_size_set
;
491 combined_cache_size_set
= qemu_opt_get(opts
, QCOW2_OPT_CACHE_SIZE
);
492 l2_cache_size_set
= qemu_opt_get(opts
, QCOW2_OPT_L2_CACHE_SIZE
);
493 refcount_cache_size_set
= qemu_opt_get(opts
, QCOW2_OPT_REFCOUNT_CACHE_SIZE
);
495 combined_cache_size
= qemu_opt_get_size(opts
, QCOW2_OPT_CACHE_SIZE
, 0);
496 *l2_cache_size
= qemu_opt_get_size(opts
, QCOW2_OPT_L2_CACHE_SIZE
, 0);
497 *refcount_cache_size
= qemu_opt_get_size(opts
,
498 QCOW2_OPT_REFCOUNT_CACHE_SIZE
, 0);
500 if (combined_cache_size_set
) {
501 if (l2_cache_size_set
&& refcount_cache_size_set
) {
502 error_setg(errp
, QCOW2_OPT_CACHE_SIZE
", " QCOW2_OPT_L2_CACHE_SIZE
503 " and " QCOW2_OPT_REFCOUNT_CACHE_SIZE
" may not be set "
506 } else if (*l2_cache_size
> combined_cache_size
) {
507 error_setg(errp
, QCOW2_OPT_L2_CACHE_SIZE
" may not exceed "
508 QCOW2_OPT_CACHE_SIZE
);
510 } else if (*refcount_cache_size
> combined_cache_size
) {
511 error_setg(errp
, QCOW2_OPT_REFCOUNT_CACHE_SIZE
" may not exceed "
512 QCOW2_OPT_CACHE_SIZE
);
516 if (l2_cache_size_set
) {
517 *refcount_cache_size
= combined_cache_size
- *l2_cache_size
;
518 } else if (refcount_cache_size_set
) {
519 *l2_cache_size
= combined_cache_size
- *refcount_cache_size
;
521 *refcount_cache_size
= combined_cache_size
522 / (DEFAULT_L2_REFCOUNT_SIZE_RATIO
+ 1);
523 *l2_cache_size
= combined_cache_size
- *refcount_cache_size
;
526 if (!l2_cache_size_set
&& !refcount_cache_size_set
) {
527 *l2_cache_size
= DEFAULT_L2_CACHE_BYTE_SIZE
;
528 *refcount_cache_size
= *l2_cache_size
529 / DEFAULT_L2_REFCOUNT_SIZE_RATIO
;
530 } else if (!l2_cache_size_set
) {
531 *l2_cache_size
= *refcount_cache_size
532 * DEFAULT_L2_REFCOUNT_SIZE_RATIO
;
533 } else if (!refcount_cache_size_set
) {
534 *refcount_cache_size
= *l2_cache_size
535 / DEFAULT_L2_REFCOUNT_SIZE_RATIO
;
540 static int qcow2_open(BlockDriverState
*bs
, QDict
*options
, int flags
,
543 BDRVQcowState
*s
= bs
->opaque
;
547 QemuOpts
*opts
= NULL
;
548 Error
*local_err
= NULL
;
550 uint64_t l1_vm_state_index
;
551 const char *opt_overlap_check
, *opt_overlap_check_template
;
552 int overlap_check_template
= 0;
553 uint64_t l2_cache_size
, refcount_cache_size
;
555 ret
= bdrv_pread(bs
->file
, 0, &header
, sizeof(header
));
557 error_setg_errno(errp
, -ret
, "Could not read qcow2 header");
560 be32_to_cpus(&header
.magic
);
561 be32_to_cpus(&header
.version
);
562 be64_to_cpus(&header
.backing_file_offset
);
563 be32_to_cpus(&header
.backing_file_size
);
564 be64_to_cpus(&header
.size
);
565 be32_to_cpus(&header
.cluster_bits
);
566 be32_to_cpus(&header
.crypt_method
);
567 be64_to_cpus(&header
.l1_table_offset
);
568 be32_to_cpus(&header
.l1_size
);
569 be64_to_cpus(&header
.refcount_table_offset
);
570 be32_to_cpus(&header
.refcount_table_clusters
);
571 be64_to_cpus(&header
.snapshots_offset
);
572 be32_to_cpus(&header
.nb_snapshots
);
574 if (header
.magic
!= QCOW_MAGIC
) {
575 error_setg(errp
, "Image is not in qcow2 format");
579 if (header
.version
< 2 || header
.version
> 3) {
580 report_unsupported(bs
, errp
, "QCOW version %" PRIu32
, header
.version
);
585 s
->qcow_version
= header
.version
;
587 /* Initialise cluster size */
588 if (header
.cluster_bits
< MIN_CLUSTER_BITS
||
589 header
.cluster_bits
> MAX_CLUSTER_BITS
) {
590 error_setg(errp
, "Unsupported cluster size: 2^%" PRIu32
,
591 header
.cluster_bits
);
596 s
->cluster_bits
= header
.cluster_bits
;
597 s
->cluster_size
= 1 << s
->cluster_bits
;
598 s
->cluster_sectors
= 1 << (s
->cluster_bits
- 9);
600 /* Initialise version 3 header fields */
601 if (header
.version
== 2) {
602 header
.incompatible_features
= 0;
603 header
.compatible_features
= 0;
604 header
.autoclear_features
= 0;
605 header
.refcount_order
= 4;
606 header
.header_length
= 72;
608 be64_to_cpus(&header
.incompatible_features
);
609 be64_to_cpus(&header
.compatible_features
);
610 be64_to_cpus(&header
.autoclear_features
);
611 be32_to_cpus(&header
.refcount_order
);
612 be32_to_cpus(&header
.header_length
);
614 if (header
.header_length
< 104) {
615 error_setg(errp
, "qcow2 header too short");
621 if (header
.header_length
> s
->cluster_size
) {
622 error_setg(errp
, "qcow2 header exceeds cluster size");
627 if (header
.header_length
> sizeof(header
)) {
628 s
->unknown_header_fields_size
= header
.header_length
- sizeof(header
);
629 s
->unknown_header_fields
= g_malloc(s
->unknown_header_fields_size
);
630 ret
= bdrv_pread(bs
->file
, sizeof(header
), s
->unknown_header_fields
,
631 s
->unknown_header_fields_size
);
633 error_setg_errno(errp
, -ret
, "Could not read unknown qcow2 header "
639 if (header
.backing_file_offset
> s
->cluster_size
) {
640 error_setg(errp
, "Invalid backing file offset");
645 if (header
.backing_file_offset
) {
646 ext_end
= header
.backing_file_offset
;
648 ext_end
= 1 << header
.cluster_bits
;
651 /* Handle feature bits */
652 s
->incompatible_features
= header
.incompatible_features
;
653 s
->compatible_features
= header
.compatible_features
;
654 s
->autoclear_features
= header
.autoclear_features
;
656 if (s
->incompatible_features
& ~QCOW2_INCOMPAT_MASK
) {
657 void *feature_table
= NULL
;
658 qcow2_read_extensions(bs
, header
.header_length
, ext_end
,
659 &feature_table
, NULL
);
660 report_unsupported_feature(bs
, errp
, feature_table
,
661 s
->incompatible_features
&
662 ~QCOW2_INCOMPAT_MASK
);
664 g_free(feature_table
);
668 if (s
->incompatible_features
& QCOW2_INCOMPAT_CORRUPT
) {
669 /* Corrupt images may not be written to unless they are being repaired
671 if ((flags
& BDRV_O_RDWR
) && !(flags
& BDRV_O_CHECK
)) {
672 error_setg(errp
, "qcow2: Image is corrupt; cannot be opened "
679 /* Check support for various header values */
680 if (header
.refcount_order
!= 4) {
681 report_unsupported(bs
, errp
, "%d bit reference counts",
682 1 << header
.refcount_order
);
686 s
->refcount_order
= header
.refcount_order
;
688 if (header
.crypt_method
> QCOW_CRYPT_AES
) {
689 error_setg(errp
, "Unsupported encryption method: %" PRIu32
,
690 header
.crypt_method
);
694 s
->crypt_method_header
= header
.crypt_method
;
695 if (s
->crypt_method_header
) {
699 s
->l2_bits
= s
->cluster_bits
- 3; /* L2 is always one cluster */
700 s
->l2_size
= 1 << s
->l2_bits
;
701 /* 2^(s->refcount_order - 3) is the refcount width in bytes */
702 s
->refcount_block_bits
= s
->cluster_bits
- (s
->refcount_order
- 3);
703 s
->refcount_block_size
= 1 << s
->refcount_block_bits
;
704 bs
->total_sectors
= header
.size
/ 512;
705 s
->csize_shift
= (62 - (s
->cluster_bits
- 8));
706 s
->csize_mask
= (1 << (s
->cluster_bits
- 8)) - 1;
707 s
->cluster_offset_mask
= (1LL << s
->csize_shift
) - 1;
709 s
->refcount_table_offset
= header
.refcount_table_offset
;
710 s
->refcount_table_size
=
711 header
.refcount_table_clusters
<< (s
->cluster_bits
- 3);
713 if (header
.refcount_table_clusters
> qcow2_max_refcount_clusters(s
)) {
714 error_setg(errp
, "Reference count table too large");
719 ret
= validate_table_offset(bs
, s
->refcount_table_offset
,
720 s
->refcount_table_size
, sizeof(uint64_t));
722 error_setg(errp
, "Invalid reference count table offset");
726 /* Snapshot table offset/length */
727 if (header
.nb_snapshots
> QCOW_MAX_SNAPSHOTS
) {
728 error_setg(errp
, "Too many snapshots");
733 ret
= validate_table_offset(bs
, header
.snapshots_offset
,
735 sizeof(QCowSnapshotHeader
));
737 error_setg(errp
, "Invalid snapshot table offset");
741 /* read the level 1 table */
742 if (header
.l1_size
> QCOW_MAX_L1_SIZE
) {
743 error_setg(errp
, "Active L1 table too large");
747 s
->l1_size
= header
.l1_size
;
749 l1_vm_state_index
= size_to_l1(s
, header
.size
);
750 if (l1_vm_state_index
> INT_MAX
) {
751 error_setg(errp
, "Image is too big");
755 s
->l1_vm_state_index
= l1_vm_state_index
;
757 /* the L1 table must contain at least enough entries to put
759 if (s
->l1_size
< s
->l1_vm_state_index
) {
760 error_setg(errp
, "L1 table is too small");
765 ret
= validate_table_offset(bs
, header
.l1_table_offset
,
766 header
.l1_size
, sizeof(uint64_t));
768 error_setg(errp
, "Invalid L1 table offset");
771 s
->l1_table_offset
= header
.l1_table_offset
;
774 if (s
->l1_size
> 0) {
775 s
->l1_table
= qemu_try_blockalign(bs
->file
,
776 align_offset(s
->l1_size
* sizeof(uint64_t), 512));
777 if (s
->l1_table
== NULL
) {
778 error_setg(errp
, "Could not allocate L1 table");
782 ret
= bdrv_pread(bs
->file
, s
->l1_table_offset
, s
->l1_table
,
783 s
->l1_size
* sizeof(uint64_t));
785 error_setg_errno(errp
, -ret
, "Could not read L1 table");
788 for(i
= 0;i
< s
->l1_size
; i
++) {
789 be64_to_cpus(&s
->l1_table
[i
]);
793 /* get L2 table/refcount block cache size from command line options */
794 opts
= qemu_opts_create(&qcow2_runtime_opts
, NULL
, 0, &error_abort
);
795 qemu_opts_absorb_qdict(opts
, options
, &local_err
);
797 error_propagate(errp
, local_err
);
802 read_cache_sizes(opts
, &l2_cache_size
, &refcount_cache_size
, &local_err
);
804 error_propagate(errp
, local_err
);
809 l2_cache_size
/= s
->cluster_size
;
810 if (l2_cache_size
< MIN_L2_CACHE_SIZE
) {
811 l2_cache_size
= MIN_L2_CACHE_SIZE
;
813 if (l2_cache_size
> INT_MAX
) {
814 error_setg(errp
, "L2 cache size too big");
819 refcount_cache_size
/= s
->cluster_size
;
820 if (refcount_cache_size
< MIN_REFCOUNT_CACHE_SIZE
) {
821 refcount_cache_size
= MIN_REFCOUNT_CACHE_SIZE
;
823 if (refcount_cache_size
> INT_MAX
) {
824 error_setg(errp
, "Refcount cache size too big");
829 /* alloc L2 table/refcount block cache */
830 s
->l2_table_cache
= qcow2_cache_create(bs
, l2_cache_size
);
831 s
->refcount_block_cache
= qcow2_cache_create(bs
, refcount_cache_size
);
832 if (s
->l2_table_cache
== NULL
|| s
->refcount_block_cache
== NULL
) {
833 error_setg(errp
, "Could not allocate metadata caches");
838 s
->cluster_cache
= g_malloc(s
->cluster_size
);
839 /* one more sector for decompressed data alignment */
840 s
->cluster_data
= qemu_try_blockalign(bs
->file
, QCOW_MAX_CRYPT_CLUSTERS
841 * s
->cluster_size
+ 512);
842 if (s
->cluster_data
== NULL
) {
843 error_setg(errp
, "Could not allocate temporary cluster buffer");
848 s
->cluster_cache_offset
= -1;
851 ret
= qcow2_refcount_init(bs
);
853 error_setg_errno(errp
, -ret
, "Could not initialize refcount handling");
857 QLIST_INIT(&s
->cluster_allocs
);
858 QTAILQ_INIT(&s
->discards
);
860 /* read qcow2 extensions */
861 if (qcow2_read_extensions(bs
, header
.header_length
, ext_end
, NULL
,
863 error_propagate(errp
, local_err
);
868 /* read the backing file name */
869 if (header
.backing_file_offset
!= 0) {
870 len
= header
.backing_file_size
;
871 if (len
> MIN(1023, s
->cluster_size
- header
.backing_file_offset
)) {
872 error_setg(errp
, "Backing file name too long");
876 ret
= bdrv_pread(bs
->file
, header
.backing_file_offset
,
877 bs
->backing_file
, len
);
879 error_setg_errno(errp
, -ret
, "Could not read backing file name");
882 bs
->backing_file
[len
] = '\0';
885 /* Internal snapshots */
886 s
->snapshots_offset
= header
.snapshots_offset
;
887 s
->nb_snapshots
= header
.nb_snapshots
;
889 ret
= qcow2_read_snapshots(bs
);
891 error_setg_errno(errp
, -ret
, "Could not read snapshots");
895 /* Clear unknown autoclear feature bits */
896 if (!bs
->read_only
&& !(flags
& BDRV_O_INCOMING
) && s
->autoclear_features
) {
897 s
->autoclear_features
= 0;
898 ret
= qcow2_update_header(bs
);
900 error_setg_errno(errp
, -ret
, "Could not update qcow2 header");
905 /* Initialise locks */
906 qemu_co_mutex_init(&s
->lock
);
908 /* Repair image if dirty */
909 if (!(flags
& (BDRV_O_CHECK
| BDRV_O_INCOMING
)) && !bs
->read_only
&&
910 (s
->incompatible_features
& QCOW2_INCOMPAT_DIRTY
)) {
911 BdrvCheckResult result
= {0};
913 ret
= qcow2_check(bs
, &result
, BDRV_FIX_ERRORS
| BDRV_FIX_LEAKS
);
915 error_setg_errno(errp
, -ret
, "Could not repair dirty image");
920 /* Enable lazy_refcounts according to image and command line options */
921 s
->use_lazy_refcounts
= qemu_opt_get_bool(opts
, QCOW2_OPT_LAZY_REFCOUNTS
,
922 (s
->compatible_features
& QCOW2_COMPAT_LAZY_REFCOUNTS
));
924 s
->discard_passthrough
[QCOW2_DISCARD_NEVER
] = false;
925 s
->discard_passthrough
[QCOW2_DISCARD_ALWAYS
] = true;
926 s
->discard_passthrough
[QCOW2_DISCARD_REQUEST
] =
927 qemu_opt_get_bool(opts
, QCOW2_OPT_DISCARD_REQUEST
,
928 flags
& BDRV_O_UNMAP
);
929 s
->discard_passthrough
[QCOW2_DISCARD_SNAPSHOT
] =
930 qemu_opt_get_bool(opts
, QCOW2_OPT_DISCARD_SNAPSHOT
, true);
931 s
->discard_passthrough
[QCOW2_DISCARD_OTHER
] =
932 qemu_opt_get_bool(opts
, QCOW2_OPT_DISCARD_OTHER
, false);
934 opt_overlap_check
= qemu_opt_get(opts
, QCOW2_OPT_OVERLAP
);
935 opt_overlap_check_template
= qemu_opt_get(opts
, QCOW2_OPT_OVERLAP_TEMPLATE
);
936 if (opt_overlap_check_template
&& opt_overlap_check
&&
937 strcmp(opt_overlap_check_template
, opt_overlap_check
))
939 error_setg(errp
, "Conflicting values for qcow2 options '"
940 QCOW2_OPT_OVERLAP
"' ('%s') and '" QCOW2_OPT_OVERLAP_TEMPLATE
941 "' ('%s')", opt_overlap_check
, opt_overlap_check_template
);
945 if (!opt_overlap_check
) {
946 opt_overlap_check
= opt_overlap_check_template
?: "cached";
949 if (!strcmp(opt_overlap_check
, "none")) {
950 overlap_check_template
= 0;
951 } else if (!strcmp(opt_overlap_check
, "constant")) {
952 overlap_check_template
= QCOW2_OL_CONSTANT
;
953 } else if (!strcmp(opt_overlap_check
, "cached")) {
954 overlap_check_template
= QCOW2_OL_CACHED
;
955 } else if (!strcmp(opt_overlap_check
, "all")) {
956 overlap_check_template
= QCOW2_OL_ALL
;
958 error_setg(errp
, "Unsupported value '%s' for qcow2 option "
959 "'overlap-check'. Allowed are either of the following: "
960 "none, constant, cached, all", opt_overlap_check
);
965 s
->overlap_check
= 0;
966 for (i
= 0; i
< QCOW2_OL_MAX_BITNR
; i
++) {
967 /* overlap-check defines a template bitmask, but every flag may be
968 * overwritten through the associated boolean option */
970 qemu_opt_get_bool(opts
, overlap_bool_option_names
[i
],
971 overlap_check_template
& (1 << i
)) << i
;
977 if (s
->use_lazy_refcounts
&& s
->qcow_version
< 3) {
978 error_setg(errp
, "Lazy refcounts require a qcow2 image with at least "
979 "qemu 1.1 compatibility level");
986 BdrvCheckResult result
= {0};
987 qcow2_check_refcounts(bs
, &result
, 0);
994 g_free(s
->unknown_header_fields
);
995 cleanup_unknown_header_ext(bs
);
996 qcow2_free_snapshots(bs
);
997 qcow2_refcount_close(bs
);
998 qemu_vfree(s
->l1_table
);
999 /* else pre-write overlap checks in cache_destroy may crash */
1001 if (s
->l2_table_cache
) {
1002 qcow2_cache_destroy(bs
, s
->l2_table_cache
);
1004 if (s
->refcount_block_cache
) {
1005 qcow2_cache_destroy(bs
, s
->refcount_block_cache
);
1007 g_free(s
->cluster_cache
);
1008 qemu_vfree(s
->cluster_data
);
1012 static void qcow2_refresh_limits(BlockDriverState
*bs
, Error
**errp
)
1014 BDRVQcowState
*s
= bs
->opaque
;
1016 bs
->bl
.write_zeroes_alignment
= s
->cluster_sectors
;
1019 static int qcow2_set_key(BlockDriverState
*bs
, const char *key
)
1021 BDRVQcowState
*s
= bs
->opaque
;
1025 memset(keybuf
, 0, 16);
1029 /* XXX: we could compress the chars to 7 bits to increase
1031 for(i
= 0;i
< len
;i
++) {
1034 s
->crypt_method
= s
->crypt_method_header
;
1036 if (AES_set_encrypt_key(keybuf
, 128, &s
->aes_encrypt_key
) != 0)
1038 if (AES_set_decrypt_key(keybuf
, 128, &s
->aes_decrypt_key
) != 0)
1048 AES_encrypt(in
, tmp
, &s
->aes_encrypt_key
);
1049 AES_decrypt(tmp
, out
, &s
->aes_decrypt_key
);
1050 for(i
= 0; i
< 16; i
++)
1051 printf(" %02x", tmp
[i
]);
1053 for(i
= 0; i
< 16; i
++)
1054 printf(" %02x", out
[i
]);
1061 /* We have no actual commit/abort logic for qcow2, but we need to write out any
1062 * unwritten data if we reopen read-only. */
1063 static int qcow2_reopen_prepare(BDRVReopenState
*state
,
1064 BlockReopenQueue
*queue
, Error
**errp
)
1068 if ((state
->flags
& BDRV_O_RDWR
) == 0) {
1069 ret
= bdrv_flush(state
->bs
);
1074 ret
= qcow2_mark_clean(state
->bs
);
1083 static int64_t coroutine_fn
qcow2_co_get_block_status(BlockDriverState
*bs
,
1084 int64_t sector_num
, int nb_sectors
, int *pnum
)
1086 BDRVQcowState
*s
= bs
->opaque
;
1087 uint64_t cluster_offset
;
1088 int index_in_cluster
, ret
;
1092 qemu_co_mutex_lock(&s
->lock
);
1093 ret
= qcow2_get_cluster_offset(bs
, sector_num
<< 9, pnum
, &cluster_offset
);
1094 qemu_co_mutex_unlock(&s
->lock
);
1099 if (cluster_offset
!= 0 && ret
!= QCOW2_CLUSTER_COMPRESSED
&&
1101 index_in_cluster
= sector_num
& (s
->cluster_sectors
- 1);
1102 cluster_offset
|= (index_in_cluster
<< BDRV_SECTOR_BITS
);
1103 status
|= BDRV_BLOCK_OFFSET_VALID
| cluster_offset
;
1105 if (ret
== QCOW2_CLUSTER_ZERO
) {
1106 status
|= BDRV_BLOCK_ZERO
;
1107 } else if (ret
!= QCOW2_CLUSTER_UNALLOCATED
) {
1108 status
|= BDRV_BLOCK_DATA
;
1113 /* handle reading after the end of the backing file */
1114 int qcow2_backing_read1(BlockDriverState
*bs
, QEMUIOVector
*qiov
,
1115 int64_t sector_num
, int nb_sectors
)
1118 if ((sector_num
+ nb_sectors
) <= bs
->total_sectors
)
1120 if (sector_num
>= bs
->total_sectors
)
1123 n1
= bs
->total_sectors
- sector_num
;
1125 qemu_iovec_memset(qiov
, 512 * n1
, 0, 512 * (nb_sectors
- n1
));
1130 static coroutine_fn
int qcow2_co_readv(BlockDriverState
*bs
, int64_t sector_num
,
1131 int remaining_sectors
, QEMUIOVector
*qiov
)
1133 BDRVQcowState
*s
= bs
->opaque
;
1134 int index_in_cluster
, n1
;
1136 int cur_nr_sectors
; /* number of sectors in current iteration */
1137 uint64_t cluster_offset
= 0;
1138 uint64_t bytes_done
= 0;
1139 QEMUIOVector hd_qiov
;
1140 uint8_t *cluster_data
= NULL
;
1142 qemu_iovec_init(&hd_qiov
, qiov
->niov
);
1144 qemu_co_mutex_lock(&s
->lock
);
1146 while (remaining_sectors
!= 0) {
1148 /* prepare next request */
1149 cur_nr_sectors
= remaining_sectors
;
1150 if (s
->crypt_method
) {
1151 cur_nr_sectors
= MIN(cur_nr_sectors
,
1152 QCOW_MAX_CRYPT_CLUSTERS
* s
->cluster_sectors
);
1155 ret
= qcow2_get_cluster_offset(bs
, sector_num
<< 9,
1156 &cur_nr_sectors
, &cluster_offset
);
1161 index_in_cluster
= sector_num
& (s
->cluster_sectors
- 1);
1163 qemu_iovec_reset(&hd_qiov
);
1164 qemu_iovec_concat(&hd_qiov
, qiov
, bytes_done
,
1165 cur_nr_sectors
* 512);
1168 case QCOW2_CLUSTER_UNALLOCATED
:
1170 if (bs
->backing_hd
) {
1171 /* read from the base image */
1172 n1
= qcow2_backing_read1(bs
->backing_hd
, &hd_qiov
,
1173 sector_num
, cur_nr_sectors
);
1175 QEMUIOVector local_qiov
;
1177 qemu_iovec_init(&local_qiov
, hd_qiov
.niov
);
1178 qemu_iovec_concat(&local_qiov
, &hd_qiov
, 0,
1179 n1
* BDRV_SECTOR_SIZE
);
1181 BLKDBG_EVENT(bs
->file
, BLKDBG_READ_BACKING_AIO
);
1182 qemu_co_mutex_unlock(&s
->lock
);
1183 ret
= bdrv_co_readv(bs
->backing_hd
, sector_num
,
1185 qemu_co_mutex_lock(&s
->lock
);
1187 qemu_iovec_destroy(&local_qiov
);
1194 /* Note: in this case, no need to wait */
1195 qemu_iovec_memset(&hd_qiov
, 0, 0, 512 * cur_nr_sectors
);
1199 case QCOW2_CLUSTER_ZERO
:
1200 qemu_iovec_memset(&hd_qiov
, 0, 0, 512 * cur_nr_sectors
);
1203 case QCOW2_CLUSTER_COMPRESSED
:
1204 /* add AIO support for compressed blocks ? */
1205 ret
= qcow2_decompress_cluster(bs
, cluster_offset
);
1210 qemu_iovec_from_buf(&hd_qiov
, 0,
1211 s
->cluster_cache
+ index_in_cluster
* 512,
1212 512 * cur_nr_sectors
);
1215 case QCOW2_CLUSTER_NORMAL
:
1216 if ((cluster_offset
& 511) != 0) {
1221 if (s
->crypt_method
) {
1223 * For encrypted images, read everything into a temporary
1224 * contiguous buffer on which the AES functions can work.
1226 if (!cluster_data
) {
1228 qemu_try_blockalign(bs
->file
, QCOW_MAX_CRYPT_CLUSTERS
1230 if (cluster_data
== NULL
) {
1236 assert(cur_nr_sectors
<=
1237 QCOW_MAX_CRYPT_CLUSTERS
* s
->cluster_sectors
);
1238 qemu_iovec_reset(&hd_qiov
);
1239 qemu_iovec_add(&hd_qiov
, cluster_data
,
1240 512 * cur_nr_sectors
);
1243 BLKDBG_EVENT(bs
->file
, BLKDBG_READ_AIO
);
1244 qemu_co_mutex_unlock(&s
->lock
);
1245 ret
= bdrv_co_readv(bs
->file
,
1246 (cluster_offset
>> 9) + index_in_cluster
,
1247 cur_nr_sectors
, &hd_qiov
);
1248 qemu_co_mutex_lock(&s
->lock
);
1252 if (s
->crypt_method
) {
1253 qcow2_encrypt_sectors(s
, sector_num
, cluster_data
,
1254 cluster_data
, cur_nr_sectors
, 0, &s
->aes_decrypt_key
);
1255 qemu_iovec_from_buf(qiov
, bytes_done
,
1256 cluster_data
, 512 * cur_nr_sectors
);
1261 g_assert_not_reached();
1266 remaining_sectors
-= cur_nr_sectors
;
1267 sector_num
+= cur_nr_sectors
;
1268 bytes_done
+= cur_nr_sectors
* 512;
1273 qemu_co_mutex_unlock(&s
->lock
);
1275 qemu_iovec_destroy(&hd_qiov
);
1276 qemu_vfree(cluster_data
);
1281 static coroutine_fn
int qcow2_co_writev(BlockDriverState
*bs
,
1283 int remaining_sectors
,
1286 BDRVQcowState
*s
= bs
->opaque
;
1287 int index_in_cluster
;
1289 int cur_nr_sectors
; /* number of sectors in current iteration */
1290 uint64_t cluster_offset
;
1291 QEMUIOVector hd_qiov
;
1292 uint64_t bytes_done
= 0;
1293 uint8_t *cluster_data
= NULL
;
1294 QCowL2Meta
*l2meta
= NULL
;
1296 trace_qcow2_writev_start_req(qemu_coroutine_self(), sector_num
,
1299 qemu_iovec_init(&hd_qiov
, qiov
->niov
);
1301 s
->cluster_cache_offset
= -1; /* disable compressed cache */
1303 qemu_co_mutex_lock(&s
->lock
);
1305 while (remaining_sectors
!= 0) {
1309 trace_qcow2_writev_start_part(qemu_coroutine_self());
1310 index_in_cluster
= sector_num
& (s
->cluster_sectors
- 1);
1311 cur_nr_sectors
= remaining_sectors
;
1312 if (s
->crypt_method
&&
1314 QCOW_MAX_CRYPT_CLUSTERS
* s
->cluster_sectors
- index_in_cluster
) {
1316 QCOW_MAX_CRYPT_CLUSTERS
* s
->cluster_sectors
- index_in_cluster
;
1319 ret
= qcow2_alloc_cluster_offset(bs
, sector_num
<< 9,
1320 &cur_nr_sectors
, &cluster_offset
, &l2meta
);
1325 assert((cluster_offset
& 511) == 0);
1327 qemu_iovec_reset(&hd_qiov
);
1328 qemu_iovec_concat(&hd_qiov
, qiov
, bytes_done
,
1329 cur_nr_sectors
* 512);
1331 if (s
->crypt_method
) {
1332 if (!cluster_data
) {
1333 cluster_data
= qemu_try_blockalign(bs
->file
,
1334 QCOW_MAX_CRYPT_CLUSTERS
1336 if (cluster_data
== NULL
) {
1342 assert(hd_qiov
.size
<=
1343 QCOW_MAX_CRYPT_CLUSTERS
* s
->cluster_size
);
1344 qemu_iovec_to_buf(&hd_qiov
, 0, cluster_data
, hd_qiov
.size
);
1346 qcow2_encrypt_sectors(s
, sector_num
, cluster_data
,
1347 cluster_data
, cur_nr_sectors
, 1, &s
->aes_encrypt_key
);
1349 qemu_iovec_reset(&hd_qiov
);
1350 qemu_iovec_add(&hd_qiov
, cluster_data
,
1351 cur_nr_sectors
* 512);
1354 ret
= qcow2_pre_write_overlap_check(bs
, 0,
1355 cluster_offset
+ index_in_cluster
* BDRV_SECTOR_SIZE
,
1356 cur_nr_sectors
* BDRV_SECTOR_SIZE
);
1361 qemu_co_mutex_unlock(&s
->lock
);
1362 BLKDBG_EVENT(bs
->file
, BLKDBG_WRITE_AIO
);
1363 trace_qcow2_writev_data(qemu_coroutine_self(),
1364 (cluster_offset
>> 9) + index_in_cluster
);
1365 ret
= bdrv_co_writev(bs
->file
,
1366 (cluster_offset
>> 9) + index_in_cluster
,
1367 cur_nr_sectors
, &hd_qiov
);
1368 qemu_co_mutex_lock(&s
->lock
);
1373 while (l2meta
!= NULL
) {
1376 ret
= qcow2_alloc_cluster_link_l2(bs
, l2meta
);
1381 /* Take the request off the list of running requests */
1382 if (l2meta
->nb_clusters
!= 0) {
1383 QLIST_REMOVE(l2meta
, next_in_flight
);
1386 qemu_co_queue_restart_all(&l2meta
->dependent_requests
);
1388 next
= l2meta
->next
;
1393 remaining_sectors
-= cur_nr_sectors
;
1394 sector_num
+= cur_nr_sectors
;
1395 bytes_done
+= cur_nr_sectors
* 512;
1396 trace_qcow2_writev_done_part(qemu_coroutine_self(), cur_nr_sectors
);
1401 qemu_co_mutex_unlock(&s
->lock
);
1403 while (l2meta
!= NULL
) {
1406 if (l2meta
->nb_clusters
!= 0) {
1407 QLIST_REMOVE(l2meta
, next_in_flight
);
1409 qemu_co_queue_restart_all(&l2meta
->dependent_requests
);
1411 next
= l2meta
->next
;
1416 qemu_iovec_destroy(&hd_qiov
);
1417 qemu_vfree(cluster_data
);
1418 trace_qcow2_writev_done_req(qemu_coroutine_self(), ret
);
1423 static void qcow2_close(BlockDriverState
*bs
)
1425 BDRVQcowState
*s
= bs
->opaque
;
1426 qemu_vfree(s
->l1_table
);
1427 /* else pre-write overlap checks in cache_destroy may crash */
1430 if (!(bs
->open_flags
& BDRV_O_INCOMING
)) {
1433 ret1
= qcow2_cache_flush(bs
, s
->l2_table_cache
);
1434 ret2
= qcow2_cache_flush(bs
, s
->refcount_block_cache
);
1437 error_report("Failed to flush the L2 table cache: %s",
1441 error_report("Failed to flush the refcount block cache: %s",
1445 if (!ret1
&& !ret2
) {
1446 qcow2_mark_clean(bs
);
1450 qcow2_cache_destroy(bs
, s
->l2_table_cache
);
1451 qcow2_cache_destroy(bs
, s
->refcount_block_cache
);
1453 g_free(s
->unknown_header_fields
);
1454 cleanup_unknown_header_ext(bs
);
1456 g_free(s
->cluster_cache
);
1457 qemu_vfree(s
->cluster_data
);
1458 qcow2_refcount_close(bs
);
1459 qcow2_free_snapshots(bs
);
1462 static void qcow2_invalidate_cache(BlockDriverState
*bs
, Error
**errp
)
1464 BDRVQcowState
*s
= bs
->opaque
;
1465 int flags
= s
->flags
;
1466 AES_KEY aes_encrypt_key
;
1467 AES_KEY aes_decrypt_key
;
1468 uint32_t crypt_method
= 0;
1470 Error
*local_err
= NULL
;
1474 * Backing files are read-only which makes all of their metadata immutable,
1475 * that means we don't have to worry about reopening them here.
1478 if (s
->crypt_method
) {
1479 crypt_method
= s
->crypt_method
;
1480 memcpy(&aes_encrypt_key
, &s
->aes_encrypt_key
, sizeof(aes_encrypt_key
));
1481 memcpy(&aes_decrypt_key
, &s
->aes_decrypt_key
, sizeof(aes_decrypt_key
));
1486 bdrv_invalidate_cache(bs
->file
, &local_err
);
1488 error_propagate(errp
, local_err
);
1492 memset(s
, 0, sizeof(BDRVQcowState
));
1493 options
= qdict_clone_shallow(bs
->options
);
1495 ret
= qcow2_open(bs
, options
, flags
, &local_err
);
1498 error_setg(errp
, "Could not reopen qcow2 layer: %s",
1499 error_get_pretty(local_err
));
1500 error_free(local_err
);
1502 } else if (ret
< 0) {
1503 error_setg_errno(errp
, -ret
, "Could not reopen qcow2 layer");
1508 s
->crypt_method
= crypt_method
;
1509 memcpy(&s
->aes_encrypt_key
, &aes_encrypt_key
, sizeof(aes_encrypt_key
));
1510 memcpy(&s
->aes_decrypt_key
, &aes_decrypt_key
, sizeof(aes_decrypt_key
));
1514 static size_t header_ext_add(char *buf
, uint32_t magic
, const void *s
,
1515 size_t len
, size_t buflen
)
1517 QCowExtension
*ext_backing_fmt
= (QCowExtension
*) buf
;
1518 size_t ext_len
= sizeof(QCowExtension
) + ((len
+ 7) & ~7);
1520 if (buflen
< ext_len
) {
1524 *ext_backing_fmt
= (QCowExtension
) {
1525 .magic
= cpu_to_be32(magic
),
1526 .len
= cpu_to_be32(len
),
1528 memcpy(buf
+ sizeof(QCowExtension
), s
, len
);
1534 * Updates the qcow2 header, including the variable length parts of it, i.e.
1535 * the backing file name and all extensions. qcow2 was not designed to allow
1536 * such changes, so if we run out of space (we can only use the first cluster)
1537 * this function may fail.
1539 * Returns 0 on success, -errno in error cases.
1541 int qcow2_update_header(BlockDriverState
*bs
)
1543 BDRVQcowState
*s
= bs
->opaque
;
1546 size_t buflen
= s
->cluster_size
;
1548 uint64_t total_size
;
1549 uint32_t refcount_table_clusters
;
1550 size_t header_length
;
1551 Qcow2UnknownHeaderExtension
*uext
;
1553 buf
= qemu_blockalign(bs
, buflen
);
1555 /* Header structure */
1556 header
= (QCowHeader
*) buf
;
1558 if (buflen
< sizeof(*header
)) {
1563 header_length
= sizeof(*header
) + s
->unknown_header_fields_size
;
1564 total_size
= bs
->total_sectors
* BDRV_SECTOR_SIZE
;
1565 refcount_table_clusters
= s
->refcount_table_size
>> (s
->cluster_bits
- 3);
1567 *header
= (QCowHeader
) {
1568 /* Version 2 fields */
1569 .magic
= cpu_to_be32(QCOW_MAGIC
),
1570 .version
= cpu_to_be32(s
->qcow_version
),
1571 .backing_file_offset
= 0,
1572 .backing_file_size
= 0,
1573 .cluster_bits
= cpu_to_be32(s
->cluster_bits
),
1574 .size
= cpu_to_be64(total_size
),
1575 .crypt_method
= cpu_to_be32(s
->crypt_method_header
),
1576 .l1_size
= cpu_to_be32(s
->l1_size
),
1577 .l1_table_offset
= cpu_to_be64(s
->l1_table_offset
),
1578 .refcount_table_offset
= cpu_to_be64(s
->refcount_table_offset
),
1579 .refcount_table_clusters
= cpu_to_be32(refcount_table_clusters
),
1580 .nb_snapshots
= cpu_to_be32(s
->nb_snapshots
),
1581 .snapshots_offset
= cpu_to_be64(s
->snapshots_offset
),
1583 /* Version 3 fields */
1584 .incompatible_features
= cpu_to_be64(s
->incompatible_features
),
1585 .compatible_features
= cpu_to_be64(s
->compatible_features
),
1586 .autoclear_features
= cpu_to_be64(s
->autoclear_features
),
1587 .refcount_order
= cpu_to_be32(s
->refcount_order
),
1588 .header_length
= cpu_to_be32(header_length
),
1591 /* For older versions, write a shorter header */
1592 switch (s
->qcow_version
) {
1594 ret
= offsetof(QCowHeader
, incompatible_features
);
1597 ret
= sizeof(*header
);
1606 memset(buf
, 0, buflen
);
1608 /* Preserve any unknown field in the header */
1609 if (s
->unknown_header_fields_size
) {
1610 if (buflen
< s
->unknown_header_fields_size
) {
1615 memcpy(buf
, s
->unknown_header_fields
, s
->unknown_header_fields_size
);
1616 buf
+= s
->unknown_header_fields_size
;
1617 buflen
-= s
->unknown_header_fields_size
;
1620 /* Backing file format header extension */
1621 if (*bs
->backing_format
) {
1622 ret
= header_ext_add(buf
, QCOW2_EXT_MAGIC_BACKING_FORMAT
,
1623 bs
->backing_format
, strlen(bs
->backing_format
),
1634 Qcow2Feature features
[] = {
1636 .type
= QCOW2_FEAT_TYPE_INCOMPATIBLE
,
1637 .bit
= QCOW2_INCOMPAT_DIRTY_BITNR
,
1638 .name
= "dirty bit",
1641 .type
= QCOW2_FEAT_TYPE_INCOMPATIBLE
,
1642 .bit
= QCOW2_INCOMPAT_CORRUPT_BITNR
,
1643 .name
= "corrupt bit",
1646 .type
= QCOW2_FEAT_TYPE_COMPATIBLE
,
1647 .bit
= QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR
,
1648 .name
= "lazy refcounts",
1652 ret
= header_ext_add(buf
, QCOW2_EXT_MAGIC_FEATURE_TABLE
,
1653 features
, sizeof(features
), buflen
);
1660 /* Keep unknown header extensions */
1661 QLIST_FOREACH(uext
, &s
->unknown_header_ext
, next
) {
1662 ret
= header_ext_add(buf
, uext
->magic
, uext
->data
, uext
->len
, buflen
);
1671 /* End of header extensions */
1672 ret
= header_ext_add(buf
, QCOW2_EXT_MAGIC_END
, NULL
, 0, buflen
);
1680 /* Backing file name */
1681 if (*bs
->backing_file
) {
1682 size_t backing_file_len
= strlen(bs
->backing_file
);
1684 if (buflen
< backing_file_len
) {
1689 /* Using strncpy is ok here, since buf is not NUL-terminated. */
1690 strncpy(buf
, bs
->backing_file
, buflen
);
1692 header
->backing_file_offset
= cpu_to_be64(buf
- ((char*) header
));
1693 header
->backing_file_size
= cpu_to_be32(backing_file_len
);
1696 /* Write the new header */
1697 ret
= bdrv_pwrite(bs
->file
, 0, header
, s
->cluster_size
);
1708 static int qcow2_change_backing_file(BlockDriverState
*bs
,
1709 const char *backing_file
, const char *backing_fmt
)
1711 pstrcpy(bs
->backing_file
, sizeof(bs
->backing_file
), backing_file
?: "");
1712 pstrcpy(bs
->backing_format
, sizeof(bs
->backing_format
), backing_fmt
?: "");
1714 return qcow2_update_header(bs
);
1717 static int preallocate(BlockDriverState
*bs
)
1719 uint64_t nb_sectors
;
1721 uint64_t host_offset
= 0;
1726 nb_sectors
= bdrv_nb_sectors(bs
);
1729 while (nb_sectors
) {
1730 num
= MIN(nb_sectors
, INT_MAX
>> BDRV_SECTOR_BITS
);
1731 ret
= qcow2_alloc_cluster_offset(bs
, offset
, &num
,
1732 &host_offset
, &meta
);
1738 QCowL2Meta
*next
= meta
->next
;
1740 ret
= qcow2_alloc_cluster_link_l2(bs
, meta
);
1742 qcow2_free_any_clusters(bs
, meta
->alloc_offset
,
1743 meta
->nb_clusters
, QCOW2_DISCARD_NEVER
);
1747 /* There are no dependent requests, but we need to remove our
1748 * request from the list of in-flight requests */
1749 QLIST_REMOVE(meta
, next_in_flight
);
1755 /* TODO Preallocate data if requested */
1758 offset
+= num
<< BDRV_SECTOR_BITS
;
1762 * It is expected that the image file is large enough to actually contain
1763 * all of the allocated clusters (otherwise we get failing reads after
1764 * EOF). Extend the image to the last allocated sector.
1766 if (host_offset
!= 0) {
1767 uint8_t buf
[BDRV_SECTOR_SIZE
];
1768 memset(buf
, 0, BDRV_SECTOR_SIZE
);
1769 ret
= bdrv_write(bs
->file
, (host_offset
>> BDRV_SECTOR_BITS
) + num
- 1,
1779 static int qcow2_create2(const char *filename
, int64_t total_size
,
1780 const char *backing_file
, const char *backing_format
,
1781 int flags
, size_t cluster_size
, PreallocMode prealloc
,
1782 QemuOpts
*opts
, int version
,
1785 /* Calculate cluster_bits */
1787 cluster_bits
= ffs(cluster_size
) - 1;
1788 if (cluster_bits
< MIN_CLUSTER_BITS
|| cluster_bits
> MAX_CLUSTER_BITS
||
1789 (1 << cluster_bits
) != cluster_size
)
1791 error_setg(errp
, "Cluster size must be a power of two between %d and "
1792 "%dk", 1 << MIN_CLUSTER_BITS
, 1 << (MAX_CLUSTER_BITS
- 10));
1797 * Open the image file and write a minimal qcow2 header.
1799 * We keep things simple and start with a zero-sized image. We also
1800 * do without refcount blocks or a L1 table for now. We'll fix the
1801 * inconsistency later.
1803 * We do need a refcount table because growing the refcount table means
1804 * allocating two new refcount blocks - the seconds of which would be at
1805 * 2 GB for 64k clusters, and we don't want to have a 2 GB initial file
1806 * size for any qcow2 image.
1808 BlockDriverState
* bs
;
1810 uint64_t* refcount_table
;
1811 Error
*local_err
= NULL
;
1814 if (prealloc
== PREALLOC_MODE_FULL
|| prealloc
== PREALLOC_MODE_FALLOC
) {
1815 int64_t meta_size
= 0;
1816 uint64_t nreftablee
, nrefblocke
, nl1e
, nl2e
;
1817 int64_t aligned_total_size
= align_offset(total_size
, cluster_size
);
1819 /* header: 1 cluster */
1820 meta_size
+= cluster_size
;
1822 /* total size of L2 tables */
1823 nl2e
= aligned_total_size
/ cluster_size
;
1824 nl2e
= align_offset(nl2e
, cluster_size
/ sizeof(uint64_t));
1825 meta_size
+= nl2e
* sizeof(uint64_t);
1827 /* total size of L1 tables */
1828 nl1e
= nl2e
* sizeof(uint64_t) / cluster_size
;
1829 nl1e
= align_offset(nl1e
, cluster_size
/ sizeof(uint64_t));
1830 meta_size
+= nl1e
* sizeof(uint64_t);
1832 /* total size of refcount blocks
1834 * note: every host cluster is reference-counted, including metadata
1835 * (even refcount blocks are recursively included).
1837 * a = total_size (this is the guest disk size)
1838 * m = meta size not including refcount blocks and refcount tables
1840 * y1 = number of refcount blocks entries
1841 * y2 = meta size including everything
1844 * y2 = y1 * sizeof(u16) + y1 * sizeof(u16) * sizeof(u64) / c + m
1846 * y1 = (a + m) / (c - sizeof(u16) - sizeof(u16) * sizeof(u64) / c)
1848 nrefblocke
= (aligned_total_size
+ meta_size
+ cluster_size
) /
1849 (cluster_size
- sizeof(uint16_t) -
1850 1.0 * sizeof(uint16_t) * sizeof(uint64_t) / cluster_size
);
1851 nrefblocke
= align_offset(nrefblocke
, cluster_size
/ sizeof(uint16_t));
1852 meta_size
+= nrefblocke
* sizeof(uint16_t);
1854 /* total size of refcount tables */
1855 nreftablee
= nrefblocke
* sizeof(uint16_t) / cluster_size
;
1856 nreftablee
= align_offset(nreftablee
, cluster_size
/ sizeof(uint64_t));
1857 meta_size
+= nreftablee
* sizeof(uint64_t);
1859 qemu_opt_set_number(opts
, BLOCK_OPT_SIZE
,
1860 aligned_total_size
+ meta_size
);
1861 qemu_opt_set(opts
, BLOCK_OPT_PREALLOC
, PreallocMode_lookup
[prealloc
]);
1864 ret
= bdrv_create_file(filename
, opts
, &local_err
);
1866 error_propagate(errp
, local_err
);
1871 ret
= bdrv_open(&bs
, filename
, NULL
, NULL
, BDRV_O_RDWR
| BDRV_O_PROTOCOL
,
1874 error_propagate(errp
, local_err
);
1878 /* Write the header */
1879 QEMU_BUILD_BUG_ON((1 << MIN_CLUSTER_BITS
) < sizeof(*header
));
1880 header
= g_malloc0(cluster_size
);
1881 *header
= (QCowHeader
) {
1882 .magic
= cpu_to_be32(QCOW_MAGIC
),
1883 .version
= cpu_to_be32(version
),
1884 .cluster_bits
= cpu_to_be32(cluster_bits
),
1885 .size
= cpu_to_be64(0),
1886 .l1_table_offset
= cpu_to_be64(0),
1887 .l1_size
= cpu_to_be32(0),
1888 .refcount_table_offset
= cpu_to_be64(cluster_size
),
1889 .refcount_table_clusters
= cpu_to_be32(1),
1890 .refcount_order
= cpu_to_be32(4),
1891 .header_length
= cpu_to_be32(sizeof(*header
)),
1894 if (flags
& BLOCK_FLAG_ENCRYPT
) {
1895 header
->crypt_method
= cpu_to_be32(QCOW_CRYPT_AES
);
1897 header
->crypt_method
= cpu_to_be32(QCOW_CRYPT_NONE
);
1900 if (flags
& BLOCK_FLAG_LAZY_REFCOUNTS
) {
1901 header
->compatible_features
|=
1902 cpu_to_be64(QCOW2_COMPAT_LAZY_REFCOUNTS
);
1905 ret
= bdrv_pwrite(bs
, 0, header
, cluster_size
);
1908 error_setg_errno(errp
, -ret
, "Could not write qcow2 header");
1912 /* Write a refcount table with one refcount block */
1913 refcount_table
= g_malloc0(2 * cluster_size
);
1914 refcount_table
[0] = cpu_to_be64(2 * cluster_size
);
1915 ret
= bdrv_pwrite(bs
, cluster_size
, refcount_table
, 2 * cluster_size
);
1916 g_free(refcount_table
);
1919 error_setg_errno(errp
, -ret
, "Could not write refcount table");
1927 * And now open the image and make it consistent first (i.e. increase the
1928 * refcount of the cluster that is occupied by the header and the refcount
1931 ret
= bdrv_open(&bs
, filename
, NULL
, NULL
,
1932 BDRV_O_RDWR
| BDRV_O_CACHE_WB
| BDRV_O_NO_FLUSH
,
1933 &bdrv_qcow2
, &local_err
);
1935 error_propagate(errp
, local_err
);
1939 ret
= qcow2_alloc_clusters(bs
, 3 * cluster_size
);
1941 error_setg_errno(errp
, -ret
, "Could not allocate clusters for qcow2 "
1942 "header and refcount table");
1945 } else if (ret
!= 0) {
1946 error_report("Huh, first cluster in empty image is already in use?");
1950 /* Okay, now that we have a valid image, let's give it the right size */
1951 ret
= bdrv_truncate(bs
, total_size
);
1953 error_setg_errno(errp
, -ret
, "Could not resize image");
1957 /* Want a backing file? There you go.*/
1959 ret
= bdrv_change_backing_file(bs
, backing_file
, backing_format
);
1961 error_setg_errno(errp
, -ret
, "Could not assign backing file '%s' "
1962 "with format '%s'", backing_file
, backing_format
);
1967 /* And if we're supposed to preallocate metadata, do that now */
1968 if (prealloc
!= PREALLOC_MODE_OFF
) {
1969 BDRVQcowState
*s
= bs
->opaque
;
1970 qemu_co_mutex_lock(&s
->lock
);
1971 ret
= preallocate(bs
);
1972 qemu_co_mutex_unlock(&s
->lock
);
1974 error_setg_errno(errp
, -ret
, "Could not preallocate metadata");
1982 /* Reopen the image without BDRV_O_NO_FLUSH to flush it before returning */
1983 ret
= bdrv_open(&bs
, filename
, NULL
, NULL
,
1984 BDRV_O_RDWR
| BDRV_O_CACHE_WB
| BDRV_O_NO_BACKING
,
1985 &bdrv_qcow2
, &local_err
);
1987 error_propagate(errp
, local_err
);
1999 static int qcow2_create(const char *filename
, QemuOpts
*opts
, Error
**errp
)
2001 char *backing_file
= NULL
;
2002 char *backing_fmt
= NULL
;
2006 size_t cluster_size
= DEFAULT_CLUSTER_SIZE
;
2007 PreallocMode prealloc
;
2009 Error
*local_err
= NULL
;
2012 /* Read out options */
2013 size
= ROUND_UP(qemu_opt_get_size_del(opts
, BLOCK_OPT_SIZE
, 0),
2015 backing_file
= qemu_opt_get_del(opts
, BLOCK_OPT_BACKING_FILE
);
2016 backing_fmt
= qemu_opt_get_del(opts
, BLOCK_OPT_BACKING_FMT
);
2017 if (qemu_opt_get_bool_del(opts
, BLOCK_OPT_ENCRYPT
, false)) {
2018 flags
|= BLOCK_FLAG_ENCRYPT
;
2020 cluster_size
= qemu_opt_get_size_del(opts
, BLOCK_OPT_CLUSTER_SIZE
,
2021 DEFAULT_CLUSTER_SIZE
);
2022 buf
= qemu_opt_get_del(opts
, BLOCK_OPT_PREALLOC
);
2023 prealloc
= qapi_enum_parse(PreallocMode_lookup
, buf
,
2024 PREALLOC_MODE_MAX
, PREALLOC_MODE_OFF
,
2027 error_propagate(errp
, local_err
);
2032 buf
= qemu_opt_get_del(opts
, BLOCK_OPT_COMPAT_LEVEL
);
2034 /* keep the default */
2035 } else if (!strcmp(buf
, "0.10")) {
2037 } else if (!strcmp(buf
, "1.1")) {
2040 error_setg(errp
, "Invalid compatibility level: '%s'", buf
);
2045 if (qemu_opt_get_bool_del(opts
, BLOCK_OPT_LAZY_REFCOUNTS
, false)) {
2046 flags
|= BLOCK_FLAG_LAZY_REFCOUNTS
;
2049 if (backing_file
&& prealloc
!= PREALLOC_MODE_OFF
) {
2050 error_setg(errp
, "Backing file and preallocation cannot be used at "
2056 if (version
< 3 && (flags
& BLOCK_FLAG_LAZY_REFCOUNTS
)) {
2057 error_setg(errp
, "Lazy refcounts only supported with compatibility "
2058 "level 1.1 and above (use compat=1.1 or greater)");
2063 ret
= qcow2_create2(filename
, size
, backing_file
, backing_fmt
, flags
,
2064 cluster_size
, prealloc
, opts
, version
, &local_err
);
2066 error_propagate(errp
, local_err
);
2070 g_free(backing_file
);
2071 g_free(backing_fmt
);
2076 static coroutine_fn
int qcow2_co_write_zeroes(BlockDriverState
*bs
,
2077 int64_t sector_num
, int nb_sectors
, BdrvRequestFlags flags
)
2080 BDRVQcowState
*s
= bs
->opaque
;
2082 /* Emulate misaligned zero writes */
2083 if (sector_num
% s
->cluster_sectors
|| nb_sectors
% s
->cluster_sectors
) {
2087 /* Whatever is left can use real zero clusters */
2088 qemu_co_mutex_lock(&s
->lock
);
2089 ret
= qcow2_zero_clusters(bs
, sector_num
<< BDRV_SECTOR_BITS
,
2091 qemu_co_mutex_unlock(&s
->lock
);
2096 static coroutine_fn
int qcow2_co_discard(BlockDriverState
*bs
,
2097 int64_t sector_num
, int nb_sectors
)
2100 BDRVQcowState
*s
= bs
->opaque
;
2102 qemu_co_mutex_lock(&s
->lock
);
2103 ret
= qcow2_discard_clusters(bs
, sector_num
<< BDRV_SECTOR_BITS
,
2104 nb_sectors
, QCOW2_DISCARD_REQUEST
, false);
2105 qemu_co_mutex_unlock(&s
->lock
);
2109 static int qcow2_truncate(BlockDriverState
*bs
, int64_t offset
)
2111 BDRVQcowState
*s
= bs
->opaque
;
2112 int64_t new_l1_size
;
2116 error_report("The new size must be a multiple of 512");
2120 /* cannot proceed if image has snapshots */
2121 if (s
->nb_snapshots
) {
2122 error_report("Can't resize an image which has snapshots");
2126 /* shrinking is currently not supported */
2127 if (offset
< bs
->total_sectors
* 512) {
2128 error_report("qcow2 doesn't support shrinking images yet");
2132 new_l1_size
= size_to_l1(s
, offset
);
2133 ret
= qcow2_grow_l1_table(bs
, new_l1_size
, true);
2138 /* write updated header.size */
2139 offset
= cpu_to_be64(offset
);
2140 ret
= bdrv_pwrite_sync(bs
->file
, offsetof(QCowHeader
, size
),
2141 &offset
, sizeof(uint64_t));
2146 s
->l1_vm_state_index
= new_l1_size
;
2150 /* XXX: put compressed sectors first, then all the cluster aligned
2151 tables to avoid losing bytes in alignment */
2152 static int qcow2_write_compressed(BlockDriverState
*bs
, int64_t sector_num
,
2153 const uint8_t *buf
, int nb_sectors
)
2155 BDRVQcowState
*s
= bs
->opaque
;
2159 uint64_t cluster_offset
;
2161 if (nb_sectors
== 0) {
2162 /* align end of file to a sector boundary to ease reading with
2163 sector based I/Os */
2164 cluster_offset
= bdrv_getlength(bs
->file
);
2165 bdrv_truncate(bs
->file
, cluster_offset
);
2169 if (nb_sectors
!= s
->cluster_sectors
) {
2172 /* Zero-pad last write if image size is not cluster aligned */
2173 if (sector_num
+ nb_sectors
== bs
->total_sectors
&&
2174 nb_sectors
< s
->cluster_sectors
) {
2175 uint8_t *pad_buf
= qemu_blockalign(bs
, s
->cluster_size
);
2176 memset(pad_buf
, 0, s
->cluster_size
);
2177 memcpy(pad_buf
, buf
, nb_sectors
* BDRV_SECTOR_SIZE
);
2178 ret
= qcow2_write_compressed(bs
, sector_num
,
2179 pad_buf
, s
->cluster_sectors
);
2180 qemu_vfree(pad_buf
);
2185 out_buf
= g_malloc(s
->cluster_size
+ (s
->cluster_size
/ 1000) + 128);
2187 /* best compression, small window, no zlib header */
2188 memset(&strm
, 0, sizeof(strm
));
2189 ret
= deflateInit2(&strm
, Z_DEFAULT_COMPRESSION
,
2191 9, Z_DEFAULT_STRATEGY
);
2197 strm
.avail_in
= s
->cluster_size
;
2198 strm
.next_in
= (uint8_t *)buf
;
2199 strm
.avail_out
= s
->cluster_size
;
2200 strm
.next_out
= out_buf
;
2202 ret
= deflate(&strm
, Z_FINISH
);
2203 if (ret
!= Z_STREAM_END
&& ret
!= Z_OK
) {
2208 out_len
= strm
.next_out
- out_buf
;
2212 if (ret
!= Z_STREAM_END
|| out_len
>= s
->cluster_size
) {
2213 /* could not compress: write normal cluster */
2214 ret
= bdrv_write(bs
, sector_num
, buf
, s
->cluster_sectors
);
2219 cluster_offset
= qcow2_alloc_compressed_cluster_offset(bs
,
2220 sector_num
<< 9, out_len
);
2221 if (!cluster_offset
) {
2225 cluster_offset
&= s
->cluster_offset_mask
;
2227 ret
= qcow2_pre_write_overlap_check(bs
, 0, cluster_offset
, out_len
);
2232 BLKDBG_EVENT(bs
->file
, BLKDBG_WRITE_COMPRESSED
);
2233 ret
= bdrv_pwrite(bs
->file
, cluster_offset
, out_buf
, out_len
);
2245 static int make_completely_empty(BlockDriverState
*bs
)
2247 BDRVQcowState
*s
= bs
->opaque
;
2248 int ret
, l1_clusters
;
2250 uint64_t *new_reftable
= NULL
;
2251 uint64_t rt_entry
, l1_size2
;
2254 uint64_t reftable_offset
;
2255 uint32_t reftable_clusters
;
2256 } QEMU_PACKED l1_ofs_rt_ofs_cls
;
2258 ret
= qcow2_cache_empty(bs
, s
->l2_table_cache
);
2263 ret
= qcow2_cache_empty(bs
, s
->refcount_block_cache
);
2268 /* Refcounts will be broken utterly */
2269 ret
= qcow2_mark_dirty(bs
);
2274 BLKDBG_EVENT(bs
->file
, BLKDBG_L1_UPDATE
);
2276 l1_clusters
= DIV_ROUND_UP(s
->l1_size
, s
->cluster_size
/ sizeof(uint64_t));
2277 l1_size2
= (uint64_t)s
->l1_size
* sizeof(uint64_t);
2279 /* After this call, neither the in-memory nor the on-disk refcount
2280 * information accurately describe the actual references */
2282 ret
= bdrv_write_zeroes(bs
->file
, s
->l1_table_offset
/ BDRV_SECTOR_SIZE
,
2283 l1_clusters
* s
->cluster_sectors
, 0);
2285 goto fail_broken_refcounts
;
2287 memset(s
->l1_table
, 0, l1_size2
);
2289 BLKDBG_EVENT(bs
->file
, BLKDBG_EMPTY_IMAGE_PREPARE
);
2291 /* Overwrite enough clusters at the beginning of the sectors to place
2292 * the refcount table, a refcount block and the L1 table in; this may
2293 * overwrite parts of the existing refcount and L1 table, which is not
2294 * an issue because the dirty flag is set, complete data loss is in fact
2295 * desired and partial data loss is consequently fine as well */
2296 ret
= bdrv_write_zeroes(bs
->file
, s
->cluster_size
/ BDRV_SECTOR_SIZE
,
2297 (2 + l1_clusters
) * s
->cluster_size
/
2298 BDRV_SECTOR_SIZE
, 0);
2299 /* This call (even if it failed overall) may have overwritten on-disk
2300 * refcount structures; in that case, the in-memory refcount information
2301 * will probably differ from the on-disk information which makes the BDS
2304 goto fail_broken_refcounts
;
2307 BLKDBG_EVENT(bs
->file
, BLKDBG_L1_UPDATE
);
2308 BLKDBG_EVENT(bs
->file
, BLKDBG_REFTABLE_UPDATE
);
2310 /* "Create" an empty reftable (one cluster) directly after the image
2311 * header and an empty L1 table three clusters after the image header;
2312 * the cluster between those two will be used as the first refblock */
2313 cpu_to_be64w(&l1_ofs_rt_ofs_cls
.l1_offset
, 3 * s
->cluster_size
);
2314 cpu_to_be64w(&l1_ofs_rt_ofs_cls
.reftable_offset
, s
->cluster_size
);
2315 cpu_to_be32w(&l1_ofs_rt_ofs_cls
.reftable_clusters
, 1);
2316 ret
= bdrv_pwrite_sync(bs
->file
, offsetof(QCowHeader
, l1_table_offset
),
2317 &l1_ofs_rt_ofs_cls
, sizeof(l1_ofs_rt_ofs_cls
));
2319 goto fail_broken_refcounts
;
2322 s
->l1_table_offset
= 3 * s
->cluster_size
;
2324 new_reftable
= g_try_new0(uint64_t, s
->cluster_size
/ sizeof(uint64_t));
2325 if (!new_reftable
) {
2327 goto fail_broken_refcounts
;
2330 s
->refcount_table_offset
= s
->cluster_size
;
2331 s
->refcount_table_size
= s
->cluster_size
/ sizeof(uint64_t);
2333 g_free(s
->refcount_table
);
2334 s
->refcount_table
= new_reftable
;
2335 new_reftable
= NULL
;
2337 /* Now the in-memory refcount information again corresponds to the on-disk
2338 * information (reftable is empty and no refblocks (the refblock cache is
2339 * empty)); however, this means some clusters (e.g. the image header) are
2340 * referenced, but not refcounted, but the normal qcow2 code assumes that
2341 * the in-memory information is always correct */
2343 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_ALLOC
);
2345 /* Enter the first refblock into the reftable */
2346 rt_entry
= cpu_to_be64(2 * s
->cluster_size
);
2347 ret
= bdrv_pwrite_sync(bs
->file
, s
->cluster_size
,
2348 &rt_entry
, sizeof(rt_entry
));
2350 goto fail_broken_refcounts
;
2352 s
->refcount_table
[0] = 2 * s
->cluster_size
;
2354 s
->free_cluster_index
= 0;
2355 assert(3 + l1_clusters
<= s
->refcount_block_size
);
2356 offset
= qcow2_alloc_clusters(bs
, 3 * s
->cluster_size
+ l1_size2
);
2359 goto fail_broken_refcounts
;
2360 } else if (offset
> 0) {
2361 error_report("First cluster in emptied image is in use");
2365 /* Now finally the in-memory information corresponds to the on-disk
2366 * structures and is correct */
2367 ret
= qcow2_mark_clean(bs
);
2372 ret
= bdrv_truncate(bs
->file
, (3 + l1_clusters
) * s
->cluster_size
);
2379 fail_broken_refcounts
:
2380 /* The BDS is unusable at this point. If we wanted to make it usable, we
2381 * would have to call qcow2_refcount_close(), qcow2_refcount_init(),
2382 * qcow2_check_refcounts(), qcow2_refcount_close() and qcow2_refcount_init()
2383 * again. However, because the functions which could have caused this error
2384 * path to be taken are used by those functions as well, it's very likely
2385 * that that sequence will fail as well. Therefore, just eject the BDS. */
2389 g_free(new_reftable
);
2393 static int qcow2_make_empty(BlockDriverState
*bs
)
2395 BDRVQcowState
*s
= bs
->opaque
;
2396 uint64_t start_sector
;
2397 int sector_step
= INT_MAX
/ BDRV_SECTOR_SIZE
;
2398 int l1_clusters
, ret
= 0;
2400 l1_clusters
= DIV_ROUND_UP(s
->l1_size
, s
->cluster_size
/ sizeof(uint64_t));
2402 if (s
->qcow_version
>= 3 && !s
->snapshots
&&
2403 3 + l1_clusters
<= s
->refcount_block_size
) {
2404 /* The following function only works for qcow2 v3 images (it requires
2405 * the dirty flag) and only as long as there are no snapshots (because
2406 * it completely empties the image). Furthermore, the L1 table and three
2407 * additional clusters (image header, refcount table, one refcount
2408 * block) have to fit inside one refcount block. */
2409 return make_completely_empty(bs
);
2412 /* This fallback code simply discards every active cluster; this is slow,
2413 * but works in all cases */
2414 for (start_sector
= 0; start_sector
< bs
->total_sectors
;
2415 start_sector
+= sector_step
)
2417 /* As this function is generally used after committing an external
2418 * snapshot, QCOW2_DISCARD_SNAPSHOT seems appropriate. Also, the
2419 * default action for this kind of discard is to pass the discard,
2420 * which will ideally result in an actually smaller image file, as
2421 * is probably desired. */
2422 ret
= qcow2_discard_clusters(bs
, start_sector
* BDRV_SECTOR_SIZE
,
2424 bs
->total_sectors
- start_sector
),
2425 QCOW2_DISCARD_SNAPSHOT
, true);
2434 static coroutine_fn
int qcow2_co_flush_to_os(BlockDriverState
*bs
)
2436 BDRVQcowState
*s
= bs
->opaque
;
2439 qemu_co_mutex_lock(&s
->lock
);
2440 ret
= qcow2_cache_flush(bs
, s
->l2_table_cache
);
2442 qemu_co_mutex_unlock(&s
->lock
);
2446 if (qcow2_need_accurate_refcounts(s
)) {
2447 ret
= qcow2_cache_flush(bs
, s
->refcount_block_cache
);
2449 qemu_co_mutex_unlock(&s
->lock
);
2453 qemu_co_mutex_unlock(&s
->lock
);
2458 static int qcow2_get_info(BlockDriverState
*bs
, BlockDriverInfo
*bdi
)
2460 BDRVQcowState
*s
= bs
->opaque
;
2461 bdi
->unallocated_blocks_are_zero
= true;
2462 bdi
->can_write_zeroes_with_unmap
= (s
->qcow_version
>= 3);
2463 bdi
->cluster_size
= s
->cluster_size
;
2464 bdi
->vm_state_offset
= qcow2_vm_state_offset(s
);
2468 static ImageInfoSpecific
*qcow2_get_specific_info(BlockDriverState
*bs
)
2470 BDRVQcowState
*s
= bs
->opaque
;
2471 ImageInfoSpecific
*spec_info
= g_new(ImageInfoSpecific
, 1);
2473 *spec_info
= (ImageInfoSpecific
){
2474 .kind
= IMAGE_INFO_SPECIFIC_KIND_QCOW2
,
2476 .qcow2
= g_new(ImageInfoSpecificQCow2
, 1),
2479 if (s
->qcow_version
== 2) {
2480 *spec_info
->qcow2
= (ImageInfoSpecificQCow2
){
2481 .compat
= g_strdup("0.10"),
2483 } else if (s
->qcow_version
== 3) {
2484 *spec_info
->qcow2
= (ImageInfoSpecificQCow2
){
2485 .compat
= g_strdup("1.1"),
2486 .lazy_refcounts
= s
->compatible_features
&
2487 QCOW2_COMPAT_LAZY_REFCOUNTS
,
2488 .has_lazy_refcounts
= true,
2489 .corrupt
= s
->incompatible_features
&
2490 QCOW2_INCOMPAT_CORRUPT
,
2491 .has_corrupt
= true,
2499 static void dump_refcounts(BlockDriverState
*bs
)
2501 BDRVQcowState
*s
= bs
->opaque
;
2502 int64_t nb_clusters
, k
, k1
, size
;
2505 size
= bdrv_getlength(bs
->file
);
2506 nb_clusters
= size_to_clusters(s
, size
);
2507 for(k
= 0; k
< nb_clusters
;) {
2509 refcount
= get_refcount(bs
, k
);
2511 while (k
< nb_clusters
&& get_refcount(bs
, k
) == refcount
)
2513 printf("%" PRId64
": refcount=%d nb=%" PRId64
"\n", k
, refcount
,
2519 static int qcow2_save_vmstate(BlockDriverState
*bs
, QEMUIOVector
*qiov
,
2522 BDRVQcowState
*s
= bs
->opaque
;
2523 int64_t total_sectors
= bs
->total_sectors
;
2524 int growable
= bs
->growable
;
2525 bool zero_beyond_eof
= bs
->zero_beyond_eof
;
2528 BLKDBG_EVENT(bs
->file
, BLKDBG_VMSTATE_SAVE
);
2530 bs
->zero_beyond_eof
= false;
2531 ret
= bdrv_pwritev(bs
, qcow2_vm_state_offset(s
) + pos
, qiov
);
2532 bs
->growable
= growable
;
2533 bs
->zero_beyond_eof
= zero_beyond_eof
;
2535 /* bdrv_co_do_writev will have increased the total_sectors value to include
2536 * the VM state - the VM state is however not an actual part of the block
2537 * device, therefore, we need to restore the old value. */
2538 bs
->total_sectors
= total_sectors
;
2543 static int qcow2_load_vmstate(BlockDriverState
*bs
, uint8_t *buf
,
2544 int64_t pos
, int size
)
2546 BDRVQcowState
*s
= bs
->opaque
;
2547 int growable
= bs
->growable
;
2548 bool zero_beyond_eof
= bs
->zero_beyond_eof
;
2551 BLKDBG_EVENT(bs
->file
, BLKDBG_VMSTATE_LOAD
);
2553 bs
->zero_beyond_eof
= false;
2554 ret
= bdrv_pread(bs
, qcow2_vm_state_offset(s
) + pos
, buf
, size
);
2555 bs
->growable
= growable
;
2556 bs
->zero_beyond_eof
= zero_beyond_eof
;
2562 * Downgrades an image's version. To achieve this, any incompatible features
2563 * have to be removed.
2565 static int qcow2_downgrade(BlockDriverState
*bs
, int target_version
,
2566 BlockDriverAmendStatusCB
*status_cb
)
2568 BDRVQcowState
*s
= bs
->opaque
;
2569 int current_version
= s
->qcow_version
;
2572 if (target_version
== current_version
) {
2574 } else if (target_version
> current_version
) {
2576 } else if (target_version
!= 2) {
2580 if (s
->refcount_order
!= 4) {
2581 /* we would have to convert the image to a refcount_order == 4 image
2582 * here; however, since qemu (at the time of writing this) does not
2583 * support anything different than 4 anyway, there is no point in doing
2584 * so right now; however, we should error out (if qemu supports this in
2585 * the future and this code has not been adapted) */
2586 error_report("qcow2_downgrade: Image refcount orders other than 4 are "
2587 "currently not supported.");
2591 /* clear incompatible features */
2592 if (s
->incompatible_features
& QCOW2_INCOMPAT_DIRTY
) {
2593 ret
= qcow2_mark_clean(bs
);
2599 /* with QCOW2_INCOMPAT_CORRUPT, it is pretty much impossible to get here in
2600 * the first place; if that happens nonetheless, returning -ENOTSUP is the
2601 * best thing to do anyway */
2603 if (s
->incompatible_features
) {
2607 /* since we can ignore compatible features, we can set them to 0 as well */
2608 s
->compatible_features
= 0;
2609 /* if lazy refcounts have been used, they have already been fixed through
2610 * clearing the dirty flag */
2612 /* clearing autoclear features is trivial */
2613 s
->autoclear_features
= 0;
2615 ret
= qcow2_expand_zero_clusters(bs
, status_cb
);
2620 s
->qcow_version
= target_version
;
2621 ret
= qcow2_update_header(bs
);
2623 s
->qcow_version
= current_version
;
2629 static int qcow2_amend_options(BlockDriverState
*bs
, QemuOpts
*opts
,
2630 BlockDriverAmendStatusCB
*status_cb
)
2632 BDRVQcowState
*s
= bs
->opaque
;
2633 int old_version
= s
->qcow_version
, new_version
= old_version
;
2634 uint64_t new_size
= 0;
2635 const char *backing_file
= NULL
, *backing_format
= NULL
;
2636 bool lazy_refcounts
= s
->use_lazy_refcounts
;
2637 const char *compat
= NULL
;
2638 uint64_t cluster_size
= s
->cluster_size
;
2641 QemuOptDesc
*desc
= opts
->list
->desc
;
2643 while (desc
&& desc
->name
) {
2644 if (!qemu_opt_find(opts
, desc
->name
)) {
2645 /* only change explicitly defined options */
2650 if (!strcmp(desc
->name
, "compat")) {
2651 compat
= qemu_opt_get(opts
, "compat");
2653 /* preserve default */
2654 } else if (!strcmp(compat
, "0.10")) {
2656 } else if (!strcmp(compat
, "1.1")) {
2659 fprintf(stderr
, "Unknown compatibility level %s.\n", compat
);
2662 } else if (!strcmp(desc
->name
, "preallocation")) {
2663 fprintf(stderr
, "Cannot change preallocation mode.\n");
2665 } else if (!strcmp(desc
->name
, "size")) {
2666 new_size
= qemu_opt_get_size(opts
, "size", 0);
2667 } else if (!strcmp(desc
->name
, "backing_file")) {
2668 backing_file
= qemu_opt_get(opts
, "backing_file");
2669 } else if (!strcmp(desc
->name
, "backing_fmt")) {
2670 backing_format
= qemu_opt_get(opts
, "backing_fmt");
2671 } else if (!strcmp(desc
->name
, "encryption")) {
2672 encrypt
= qemu_opt_get_bool(opts
, "encryption", s
->crypt_method
);
2673 if (encrypt
!= !!s
->crypt_method
) {
2674 fprintf(stderr
, "Changing the encryption flag is not "
2678 } else if (!strcmp(desc
->name
, "cluster_size")) {
2679 cluster_size
= qemu_opt_get_size(opts
, "cluster_size",
2681 if (cluster_size
!= s
->cluster_size
) {
2682 fprintf(stderr
, "Changing the cluster size is not "
2686 } else if (!strcmp(desc
->name
, "lazy_refcounts")) {
2687 lazy_refcounts
= qemu_opt_get_bool(opts
, "lazy_refcounts",
2690 /* if this assertion fails, this probably means a new option was
2691 * added without having it covered here */
2698 if (new_version
!= old_version
) {
2699 if (new_version
> old_version
) {
2701 s
->qcow_version
= new_version
;
2702 ret
= qcow2_update_header(bs
);
2704 s
->qcow_version
= old_version
;
2708 ret
= qcow2_downgrade(bs
, new_version
, status_cb
);
2715 if (backing_file
|| backing_format
) {
2716 ret
= qcow2_change_backing_file(bs
, backing_file
?: bs
->backing_file
,
2717 backing_format
?: bs
->backing_format
);
2723 if (s
->use_lazy_refcounts
!= lazy_refcounts
) {
2724 if (lazy_refcounts
) {
2725 if (s
->qcow_version
< 3) {
2726 fprintf(stderr
, "Lazy refcounts only supported with compatibility "
2727 "level 1.1 and above (use compat=1.1 or greater)\n");
2730 s
->compatible_features
|= QCOW2_COMPAT_LAZY_REFCOUNTS
;
2731 ret
= qcow2_update_header(bs
);
2733 s
->compatible_features
&= ~QCOW2_COMPAT_LAZY_REFCOUNTS
;
2736 s
->use_lazy_refcounts
= true;
2738 /* make image clean first */
2739 ret
= qcow2_mark_clean(bs
);
2743 /* now disallow lazy refcounts */
2744 s
->compatible_features
&= ~QCOW2_COMPAT_LAZY_REFCOUNTS
;
2745 ret
= qcow2_update_header(bs
);
2747 s
->compatible_features
|= QCOW2_COMPAT_LAZY_REFCOUNTS
;
2750 s
->use_lazy_refcounts
= false;
2755 ret
= bdrv_truncate(bs
, new_size
);
2765 * If offset or size are negative, respectively, they will not be included in
2766 * the BLOCK_IMAGE_CORRUPTED event emitted.
2767 * fatal will be ignored for read-only BDS; corruptions found there will always
2768 * be considered non-fatal.
2770 void qcow2_signal_corruption(BlockDriverState
*bs
, bool fatal
, int64_t offset
,
2771 int64_t size
, const char *message_format
, ...)
2773 BDRVQcowState
*s
= bs
->opaque
;
2777 fatal
= fatal
&& !bs
->read_only
;
2779 if (s
->signaled_corruption
&&
2780 (!fatal
|| (s
->incompatible_features
& QCOW2_INCOMPAT_CORRUPT
)))
2785 va_start(ap
, message_format
);
2786 message
= g_strdup_vprintf(message_format
, ap
);
2790 fprintf(stderr
, "qcow2: Marking image as corrupt: %s; further "
2791 "corruption events will be suppressed\n", message
);
2793 fprintf(stderr
, "qcow2: Image is corrupt: %s; further non-fatal "
2794 "corruption events will be suppressed\n", message
);
2797 qapi_event_send_block_image_corrupted(bdrv_get_device_name(bs
), message
,
2798 offset
>= 0, offset
, size
>= 0, size
,
2799 fatal
, &error_abort
);
2803 qcow2_mark_corrupt(bs
);
2804 bs
->drv
= NULL
; /* make BDS unusable */
2807 s
->signaled_corruption
= true;
2810 static QemuOptsList qcow2_create_opts
= {
2811 .name
= "qcow2-create-opts",
2812 .head
= QTAILQ_HEAD_INITIALIZER(qcow2_create_opts
.head
),
2815 .name
= BLOCK_OPT_SIZE
,
2816 .type
= QEMU_OPT_SIZE
,
2817 .help
= "Virtual disk size"
2820 .name
= BLOCK_OPT_COMPAT_LEVEL
,
2821 .type
= QEMU_OPT_STRING
,
2822 .help
= "Compatibility level (0.10 or 1.1)"
2825 .name
= BLOCK_OPT_BACKING_FILE
,
2826 .type
= QEMU_OPT_STRING
,
2827 .help
= "File name of a base image"
2830 .name
= BLOCK_OPT_BACKING_FMT
,
2831 .type
= QEMU_OPT_STRING
,
2832 .help
= "Image format of the base image"
2835 .name
= BLOCK_OPT_ENCRYPT
,
2836 .type
= QEMU_OPT_BOOL
,
2837 .help
= "Encrypt the image",
2838 .def_value_str
= "off"
2841 .name
= BLOCK_OPT_CLUSTER_SIZE
,
2842 .type
= QEMU_OPT_SIZE
,
2843 .help
= "qcow2 cluster size",
2844 .def_value_str
= stringify(DEFAULT_CLUSTER_SIZE
)
2847 .name
= BLOCK_OPT_PREALLOC
,
2848 .type
= QEMU_OPT_STRING
,
2849 .help
= "Preallocation mode (allowed values: off, metadata, "
2853 .name
= BLOCK_OPT_LAZY_REFCOUNTS
,
2854 .type
= QEMU_OPT_BOOL
,
2855 .help
= "Postpone refcount updates",
2856 .def_value_str
= "off"
2858 { /* end of list */ }
2862 BlockDriver bdrv_qcow2
= {
2863 .format_name
= "qcow2",
2864 .instance_size
= sizeof(BDRVQcowState
),
2865 .bdrv_probe
= qcow2_probe
,
2866 .bdrv_open
= qcow2_open
,
2867 .bdrv_close
= qcow2_close
,
2868 .bdrv_reopen_prepare
= qcow2_reopen_prepare
,
2869 .bdrv_create
= qcow2_create
,
2870 .bdrv_has_zero_init
= bdrv_has_zero_init_1
,
2871 .bdrv_co_get_block_status
= qcow2_co_get_block_status
,
2872 .bdrv_set_key
= qcow2_set_key
,
2874 .bdrv_co_readv
= qcow2_co_readv
,
2875 .bdrv_co_writev
= qcow2_co_writev
,
2876 .bdrv_co_flush_to_os
= qcow2_co_flush_to_os
,
2878 .bdrv_co_write_zeroes
= qcow2_co_write_zeroes
,
2879 .bdrv_co_discard
= qcow2_co_discard
,
2880 .bdrv_truncate
= qcow2_truncate
,
2881 .bdrv_write_compressed
= qcow2_write_compressed
,
2882 .bdrv_make_empty
= qcow2_make_empty
,
2884 .bdrv_snapshot_create
= qcow2_snapshot_create
,
2885 .bdrv_snapshot_goto
= qcow2_snapshot_goto
,
2886 .bdrv_snapshot_delete
= qcow2_snapshot_delete
,
2887 .bdrv_snapshot_list
= qcow2_snapshot_list
,
2888 .bdrv_snapshot_load_tmp
= qcow2_snapshot_load_tmp
,
2889 .bdrv_get_info
= qcow2_get_info
,
2890 .bdrv_get_specific_info
= qcow2_get_specific_info
,
2892 .bdrv_save_vmstate
= qcow2_save_vmstate
,
2893 .bdrv_load_vmstate
= qcow2_load_vmstate
,
2895 .supports_backing
= true,
2896 .bdrv_change_backing_file
= qcow2_change_backing_file
,
2898 .bdrv_refresh_limits
= qcow2_refresh_limits
,
2899 .bdrv_invalidate_cache
= qcow2_invalidate_cache
,
2901 .create_opts
= &qcow2_create_opts
,
2902 .bdrv_check
= qcow2_check
,
2903 .bdrv_amend_options
= qcow2_amend_options
,
2906 static void bdrv_qcow2_init(void)
2908 bdrv_register(&bdrv_qcow2
);
2911 block_init(bdrv_qcow2_init
);