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"
28 #include "block/qcow2.h"
29 #include "qemu/error-report.h"
30 #include "qapi/qmp/qerror.h"
31 #include "qapi/qmp/qbool.h"
32 #include "qapi/util.h"
33 #include "qapi/qmp/types.h"
34 #include "qapi-event.h"
36 #include "qemu/option_int.h"
39 Differences with QCOW:
41 - Support for multiple incremental snapshots.
42 - Memory management by reference counts.
43 - Clusters which have a reference count of one have the bit
44 QCOW_OFLAG_COPIED to optimize write performance.
45 - Size of compressed clusters is stored in sectors to reduce bit usage
46 in the cluster offsets.
47 - Support for storing additional data (such as the VM state) in the
49 - If a backing store is used, the cluster size is not constrained
50 (could be backported to QCOW).
51 - L2 tables have always a size of one cluster.
58 } QEMU_PACKED QCowExtension;
60 #define QCOW2_EXT_MAGIC_END 0
61 #define QCOW2_EXT_MAGIC_BACKING_FORMAT 0xE2792ACA
62 #define QCOW2_EXT_MAGIC_FEATURE_TABLE 0x6803f857
64 static int qcow2_probe(const uint8_t *buf, int buf_size, const char *filename)
66 const QCowHeader *cow_header = (const void *)buf;
68 if (buf_size >= sizeof(QCowHeader) &&
69 be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
70 be32_to_cpu(cow_header->version) >= 2)
78 * read qcow2 extension and fill bs
79 * start reading from start_offset
80 * finish reading upon magic of value 0 or when end_offset reached
81 * unknown magic is skipped (future extension this version knows nothing about)
82 * return 0 upon success, non-0 otherwise
84 static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset,
85 uint64_t end_offset, void **p_feature_table,
88 BDRVQcowState *s = bs->opaque;
94 printf("qcow2_read_extensions: start=%ld end=%ld\n", start_offset, end_offset);
96 offset = start_offset;
97 while (offset < end_offset) {
101 if (offset > s->cluster_size)
102 printf("qcow2_read_extension: suspicious offset %lu\n", offset);
104 printf("attempting to read extended header in offset %lu\n", offset);
107 ret = bdrv_pread(bs->file, offset, &ext, sizeof(ext));
109 error_setg_errno(errp, -ret, "qcow2_read_extension: ERROR: "
110 "pread fail from offset %" PRIu64, offset);
113 be32_to_cpus(&ext.magic);
114 be32_to_cpus(&ext.len);
115 offset += sizeof(ext);
117 printf("ext.magic = 0x%x\n", ext.magic);
119 if (offset > end_offset || ext.len > end_offset - offset) {
120 error_setg(errp, "Header extension too large");
125 case QCOW2_EXT_MAGIC_END:
128 case QCOW2_EXT_MAGIC_BACKING_FORMAT:
129 if (ext.len >= sizeof(bs->backing_format)) {
130 error_setg(errp, "ERROR: ext_backing_format: len=%" PRIu32
131 " too large (>=%zu)", ext.len,
132 sizeof(bs->backing_format));
135 ret = bdrv_pread(bs->file, offset, bs->backing_format, ext.len);
137 error_setg_errno(errp, -ret, "ERROR: ext_backing_format: "
138 "Could not read format name");
141 bs->backing_format[ext.len] = '\0';
142 s->image_backing_format = g_strdup(bs->backing_format);
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_setg(errp, QERR_UNKNOWN_BLOCK_FORMAT_FEATURE,
210 bdrv_get_device_or_node_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(BlockDriverState *bs, QemuOpts *opts,
486 uint64_t *l2_cache_size,
487 uint64_t *refcount_cache_size, Error **errp)
489 BDRVQcowState *s = bs->opaque;
490 uint64_t combined_cache_size;
491 bool l2_cache_size_set, refcount_cache_size_set, combined_cache_size_set;
493 combined_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_CACHE_SIZE);
494 l2_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_L2_CACHE_SIZE);
495 refcount_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_REFCOUNT_CACHE_SIZE);
497 combined_cache_size = qemu_opt_get_size(opts, QCOW2_OPT_CACHE_SIZE, 0);
498 *l2_cache_size = qemu_opt_get_size(opts, QCOW2_OPT_L2_CACHE_SIZE, 0);
499 *refcount_cache_size = qemu_opt_get_size(opts,
500 QCOW2_OPT_REFCOUNT_CACHE_SIZE, 0);
502 if (combined_cache_size_set) {
503 if (l2_cache_size_set && refcount_cache_size_set) {
504 error_setg(errp, QCOW2_OPT_CACHE_SIZE ", " QCOW2_OPT_L2_CACHE_SIZE
505 " and " QCOW2_OPT_REFCOUNT_CACHE_SIZE " may not be set "
508 } else if (*l2_cache_size > combined_cache_size) {
509 error_setg(errp, QCOW2_OPT_L2_CACHE_SIZE " may not exceed "
510 QCOW2_OPT_CACHE_SIZE);
512 } else if (*refcount_cache_size > combined_cache_size) {
513 error_setg(errp, QCOW2_OPT_REFCOUNT_CACHE_SIZE " may not exceed "
514 QCOW2_OPT_CACHE_SIZE);
518 if (l2_cache_size_set) {
519 *refcount_cache_size = combined_cache_size - *l2_cache_size;
520 } else if (refcount_cache_size_set) {
521 *l2_cache_size = combined_cache_size - *refcount_cache_size;
523 *refcount_cache_size = combined_cache_size
524 / (DEFAULT_L2_REFCOUNT_SIZE_RATIO + 1);
525 *l2_cache_size = combined_cache_size - *refcount_cache_size;
528 if (!l2_cache_size_set && !refcount_cache_size_set) {
529 *l2_cache_size = MAX(DEFAULT_L2_CACHE_BYTE_SIZE,
530 (uint64_t)DEFAULT_L2_CACHE_CLUSTERS
532 *refcount_cache_size = *l2_cache_size
533 / DEFAULT_L2_REFCOUNT_SIZE_RATIO;
534 } else if (!l2_cache_size_set) {
535 *l2_cache_size = *refcount_cache_size
536 * DEFAULT_L2_REFCOUNT_SIZE_RATIO;
537 } else if (!refcount_cache_size_set) {
538 *refcount_cache_size = *l2_cache_size
539 / DEFAULT_L2_REFCOUNT_SIZE_RATIO;
544 static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
547 BDRVQcowState *s = bs->opaque;
551 QemuOpts *opts = NULL;
552 Error *local_err = NULL;
554 uint64_t l1_vm_state_index;
555 const char *opt_overlap_check, *opt_overlap_check_template;
556 int overlap_check_template = 0;
557 uint64_t l2_cache_size, refcount_cache_size;
559 ret = bdrv_pread(bs->file, 0, &header, sizeof(header));
561 error_setg_errno(errp, -ret, "Could not read qcow2 header");
564 be32_to_cpus(&header.magic);
565 be32_to_cpus(&header.version);
566 be64_to_cpus(&header.backing_file_offset);
567 be32_to_cpus(&header.backing_file_size);
568 be64_to_cpus(&header.size);
569 be32_to_cpus(&header.cluster_bits);
570 be32_to_cpus(&header.crypt_method);
571 be64_to_cpus(&header.l1_table_offset);
572 be32_to_cpus(&header.l1_size);
573 be64_to_cpus(&header.refcount_table_offset);
574 be32_to_cpus(&header.refcount_table_clusters);
575 be64_to_cpus(&header.snapshots_offset);
576 be32_to_cpus(&header.nb_snapshots);
578 if (header.magic != QCOW_MAGIC) {
579 error_setg(errp, "Image is not in qcow2 format");
583 if (header.version < 2 || header.version > 3) {
584 report_unsupported(bs, errp, "QCOW version %" PRIu32, header.version);
589 s->qcow_version = header.version;
591 /* Initialise cluster size */
592 if (header.cluster_bits < MIN_CLUSTER_BITS ||
593 header.cluster_bits > MAX_CLUSTER_BITS) {
594 error_setg(errp, "Unsupported cluster size: 2^%" PRIu32,
595 header.cluster_bits);
600 s->cluster_bits = header.cluster_bits;
601 s->cluster_size = 1 << s->cluster_bits;
602 s->cluster_sectors = 1 << (s->cluster_bits - 9);
604 /* Initialise version 3 header fields */
605 if (header.version == 2) {
606 header.incompatible_features = 0;
607 header.compatible_features = 0;
608 header.autoclear_features = 0;
609 header.refcount_order = 4;
610 header.header_length = 72;
612 be64_to_cpus(&header.incompatible_features);
613 be64_to_cpus(&header.compatible_features);
614 be64_to_cpus(&header.autoclear_features);
615 be32_to_cpus(&header.refcount_order);
616 be32_to_cpus(&header.header_length);
618 if (header.header_length < 104) {
619 error_setg(errp, "qcow2 header too short");
625 if (header.header_length > s->cluster_size) {
626 error_setg(errp, "qcow2 header exceeds cluster size");
631 if (header.header_length > sizeof(header)) {
632 s->unknown_header_fields_size = header.header_length - sizeof(header);
633 s->unknown_header_fields = g_malloc(s->unknown_header_fields_size);
634 ret = bdrv_pread(bs->file, sizeof(header), s->unknown_header_fields,
635 s->unknown_header_fields_size);
637 error_setg_errno(errp, -ret, "Could not read unknown qcow2 header "
643 if (header.backing_file_offset > s->cluster_size) {
644 error_setg(errp, "Invalid backing file offset");
649 if (header.backing_file_offset) {
650 ext_end = header.backing_file_offset;
652 ext_end = 1 << header.cluster_bits;
655 /* Handle feature bits */
656 s->incompatible_features = header.incompatible_features;
657 s->compatible_features = header.compatible_features;
658 s->autoclear_features = header.autoclear_features;
660 if (s->incompatible_features & ~QCOW2_INCOMPAT_MASK) {
661 void *feature_table = NULL;
662 qcow2_read_extensions(bs, header.header_length, ext_end,
663 &feature_table, NULL);
664 report_unsupported_feature(bs, errp, feature_table,
665 s->incompatible_features &
666 ~QCOW2_INCOMPAT_MASK);
668 g_free(feature_table);
672 if (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT) {
673 /* Corrupt images may not be written to unless they are being repaired
675 if ((flags & BDRV_O_RDWR) && !(flags & BDRV_O_CHECK)) {
676 error_setg(errp, "qcow2: Image is corrupt; cannot be opened "
683 /* Check support for various header values */
684 if (header.refcount_order > 6) {
685 error_setg(errp, "Reference count entry width too large; may not "
690 s->refcount_order = header.refcount_order;
691 s->refcount_bits = 1 << s->refcount_order;
692 s->refcount_max = UINT64_C(1) << (s->refcount_bits - 1);
693 s->refcount_max += s->refcount_max - 1;
695 if (header.crypt_method > QCOW_CRYPT_AES) {
696 error_setg(errp, "Unsupported encryption method: %" PRIu32,
697 header.crypt_method);
701 if (!qcrypto_cipher_supports(QCRYPTO_CIPHER_ALG_AES_128)) {
702 error_setg(errp, "AES cipher not available");
706 s->crypt_method_header = header.crypt_method;
707 if (s->crypt_method_header) {
711 s->l2_bits = s->cluster_bits - 3; /* L2 is always one cluster */
712 s->l2_size = 1 << s->l2_bits;
713 /* 2^(s->refcount_order - 3) is the refcount width in bytes */
714 s->refcount_block_bits = s->cluster_bits - (s->refcount_order - 3);
715 s->refcount_block_size = 1 << s->refcount_block_bits;
716 bs->total_sectors = header.size / 512;
717 s->csize_shift = (62 - (s->cluster_bits - 8));
718 s->csize_mask = (1 << (s->cluster_bits - 8)) - 1;
719 s->cluster_offset_mask = (1LL << s->csize_shift) - 1;
721 s->refcount_table_offset = header.refcount_table_offset;
722 s->refcount_table_size =
723 header.refcount_table_clusters << (s->cluster_bits - 3);
725 if (header.refcount_table_clusters > qcow2_max_refcount_clusters(s)) {
726 error_setg(errp, "Reference count table too large");
731 ret = validate_table_offset(bs, s->refcount_table_offset,
732 s->refcount_table_size, sizeof(uint64_t));
734 error_setg(errp, "Invalid reference count table offset");
738 /* Snapshot table offset/length */
739 if (header.nb_snapshots > QCOW_MAX_SNAPSHOTS) {
740 error_setg(errp, "Too many snapshots");
745 ret = validate_table_offset(bs, header.snapshots_offset,
747 sizeof(QCowSnapshotHeader));
749 error_setg(errp, "Invalid snapshot table offset");
753 /* read the level 1 table */
754 if (header.l1_size > QCOW_MAX_L1_SIZE / sizeof(uint64_t)) {
755 error_setg(errp, "Active L1 table too large");
759 s->l1_size = header.l1_size;
761 l1_vm_state_index = size_to_l1(s, header.size);
762 if (l1_vm_state_index > INT_MAX) {
763 error_setg(errp, "Image is too big");
767 s->l1_vm_state_index = l1_vm_state_index;
769 /* the L1 table must contain at least enough entries to put
771 if (s->l1_size < s->l1_vm_state_index) {
772 error_setg(errp, "L1 table is too small");
777 ret = validate_table_offset(bs, header.l1_table_offset,
778 header.l1_size, sizeof(uint64_t));
780 error_setg(errp, "Invalid L1 table offset");
783 s->l1_table_offset = header.l1_table_offset;
786 if (s->l1_size > 0) {
787 s->l1_table = qemu_try_blockalign(bs->file,
788 align_offset(s->l1_size * sizeof(uint64_t), 512));
789 if (s->l1_table == NULL) {
790 error_setg(errp, "Could not allocate L1 table");
794 ret = bdrv_pread(bs->file, s->l1_table_offset, s->l1_table,
795 s->l1_size * sizeof(uint64_t));
797 error_setg_errno(errp, -ret, "Could not read L1 table");
800 for(i = 0;i < s->l1_size; i++) {
801 be64_to_cpus(&s->l1_table[i]);
805 /* get L2 table/refcount block cache size from command line options */
806 opts = qemu_opts_create(&qcow2_runtime_opts, NULL, 0, &error_abort);
807 qemu_opts_absorb_qdict(opts, options, &local_err);
809 error_propagate(errp, local_err);
814 read_cache_sizes(bs, opts, &l2_cache_size, &refcount_cache_size,
817 error_propagate(errp, local_err);
822 l2_cache_size /= s->cluster_size;
823 if (l2_cache_size < MIN_L2_CACHE_SIZE) {
824 l2_cache_size = MIN_L2_CACHE_SIZE;
826 if (l2_cache_size > INT_MAX) {
827 error_setg(errp, "L2 cache size too big");
832 refcount_cache_size /= s->cluster_size;
833 if (refcount_cache_size < MIN_REFCOUNT_CACHE_SIZE) {
834 refcount_cache_size = MIN_REFCOUNT_CACHE_SIZE;
836 if (refcount_cache_size > INT_MAX) {
837 error_setg(errp, "Refcount cache size too big");
842 /* alloc L2 table/refcount block cache */
843 s->l2_table_cache = qcow2_cache_create(bs, l2_cache_size);
844 s->refcount_block_cache = qcow2_cache_create(bs, refcount_cache_size);
845 if (s->l2_table_cache == NULL || s->refcount_block_cache == NULL) {
846 error_setg(errp, "Could not allocate metadata caches");
851 s->cluster_cache = g_malloc(s->cluster_size);
852 /* one more sector for decompressed data alignment */
853 s->cluster_data = qemu_try_blockalign(bs->file, QCOW_MAX_CRYPT_CLUSTERS
854 * s->cluster_size + 512);
855 if (s->cluster_data == NULL) {
856 error_setg(errp, "Could not allocate temporary cluster buffer");
861 s->cluster_cache_offset = -1;
864 ret = qcow2_refcount_init(bs);
866 error_setg_errno(errp, -ret, "Could not initialize refcount handling");
870 QLIST_INIT(&s->cluster_allocs);
871 QTAILQ_INIT(&s->discards);
873 /* read qcow2 extensions */
874 if (qcow2_read_extensions(bs, header.header_length, ext_end, NULL,
876 error_propagate(errp, local_err);
881 /* read the backing file name */
882 if (header.backing_file_offset != 0) {
883 len = header.backing_file_size;
884 if (len > MIN(1023, s->cluster_size - header.backing_file_offset) ||
885 len >= sizeof(bs->backing_file)) {
886 error_setg(errp, "Backing file name too long");
890 ret = bdrv_pread(bs->file, header.backing_file_offset,
891 bs->backing_file, len);
893 error_setg_errno(errp, -ret, "Could not read backing file name");
896 bs->backing_file[len] = '\0';
897 s->image_backing_file = g_strdup(bs->backing_file);
900 /* Internal snapshots */
901 s->snapshots_offset = header.snapshots_offset;
902 s->nb_snapshots = header.nb_snapshots;
904 ret = qcow2_read_snapshots(bs);
906 error_setg_errno(errp, -ret, "Could not read snapshots");
910 /* Clear unknown autoclear feature bits */
911 if (!bs->read_only && !(flags & BDRV_O_INCOMING) && s->autoclear_features) {
912 s->autoclear_features = 0;
913 ret = qcow2_update_header(bs);
915 error_setg_errno(errp, -ret, "Could not update qcow2 header");
920 /* Initialise locks */
921 qemu_co_mutex_init(&s->lock);
923 /* Repair image if dirty */
924 if (!(flags & (BDRV_O_CHECK | BDRV_O_INCOMING)) && !bs->read_only &&
925 (s->incompatible_features & QCOW2_INCOMPAT_DIRTY)) {
926 BdrvCheckResult result = {0};
928 ret = qcow2_check(bs, &result, BDRV_FIX_ERRORS | BDRV_FIX_LEAKS);
930 error_setg_errno(errp, -ret, "Could not repair dirty image");
935 /* Enable lazy_refcounts according to image and command line options */
936 s->use_lazy_refcounts = qemu_opt_get_bool(opts, QCOW2_OPT_LAZY_REFCOUNTS,
937 (s->compatible_features & QCOW2_COMPAT_LAZY_REFCOUNTS));
939 s->discard_passthrough[QCOW2_DISCARD_NEVER] = false;
940 s->discard_passthrough[QCOW2_DISCARD_ALWAYS] = true;
941 s->discard_passthrough[QCOW2_DISCARD_REQUEST] =
942 qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_REQUEST,
943 flags & BDRV_O_UNMAP);
944 s->discard_passthrough[QCOW2_DISCARD_SNAPSHOT] =
945 qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_SNAPSHOT, true);
946 s->discard_passthrough[QCOW2_DISCARD_OTHER] =
947 qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_OTHER, false);
949 opt_overlap_check = qemu_opt_get(opts, QCOW2_OPT_OVERLAP);
950 opt_overlap_check_template = qemu_opt_get(opts, QCOW2_OPT_OVERLAP_TEMPLATE);
951 if (opt_overlap_check_template && opt_overlap_check &&
952 strcmp(opt_overlap_check_template, opt_overlap_check))
954 error_setg(errp, "Conflicting values for qcow2 options '"
955 QCOW2_OPT_OVERLAP "' ('%s') and '" QCOW2_OPT_OVERLAP_TEMPLATE
956 "' ('%s')", opt_overlap_check, opt_overlap_check_template);
960 if (!opt_overlap_check) {
961 opt_overlap_check = opt_overlap_check_template ?: "cached";
964 if (!strcmp(opt_overlap_check, "none")) {
965 overlap_check_template = 0;
966 } else if (!strcmp(opt_overlap_check, "constant")) {
967 overlap_check_template = QCOW2_OL_CONSTANT;
968 } else if (!strcmp(opt_overlap_check, "cached")) {
969 overlap_check_template = QCOW2_OL_CACHED;
970 } else if (!strcmp(opt_overlap_check, "all")) {
971 overlap_check_template = QCOW2_OL_ALL;
973 error_setg(errp, "Unsupported value '%s' for qcow2 option "
974 "'overlap-check'. Allowed are either of the following: "
975 "none, constant, cached, all", opt_overlap_check);
980 s->overlap_check = 0;
981 for (i = 0; i < QCOW2_OL_MAX_BITNR; i++) {
982 /* overlap-check defines a template bitmask, but every flag may be
983 * overwritten through the associated boolean option */
985 qemu_opt_get_bool(opts, overlap_bool_option_names[i],
986 overlap_check_template & (1 << i)) << i;
992 if (s->use_lazy_refcounts && s->qcow_version < 3) {
993 error_setg(errp, "Lazy refcounts require a qcow2 image with at least "
994 "qemu 1.1 compatibility level");
1001 BdrvCheckResult result = {0};
1002 qcow2_check_refcounts(bs, &result, 0);
1008 qemu_opts_del(opts);
1009 g_free(s->unknown_header_fields);
1010 cleanup_unknown_header_ext(bs);
1011 qcow2_free_snapshots(bs);
1012 qcow2_refcount_close(bs);
1013 qemu_vfree(s->l1_table);
1014 /* else pre-write overlap checks in cache_destroy may crash */
1016 if (s->l2_table_cache) {
1017 qcow2_cache_destroy(bs, s->l2_table_cache);
1019 if (s->refcount_block_cache) {
1020 qcow2_cache_destroy(bs, s->refcount_block_cache);
1022 g_free(s->cluster_cache);
1023 qemu_vfree(s->cluster_data);
1027 static void qcow2_refresh_limits(BlockDriverState *bs, Error **errp)
1029 BDRVQcowState *s = bs->opaque;
1031 bs->bl.write_zeroes_alignment = s->cluster_sectors;
1034 static int qcow2_set_key(BlockDriverState *bs, const char *key)
1036 BDRVQcowState *s = bs->opaque;
1041 memset(keybuf, 0, 16);
1045 /* XXX: we could compress the chars to 7 bits to increase
1047 for(i = 0;i < len;i++) {
1050 assert(bs->encrypted);
1052 qcrypto_cipher_free(s->cipher);
1053 s->cipher = qcrypto_cipher_new(
1054 QCRYPTO_CIPHER_ALG_AES_128,
1055 QCRYPTO_CIPHER_MODE_CBC,
1056 keybuf, G_N_ELEMENTS(keybuf),
1060 /* XXX would be nice if errors in this method could
1061 * be properly propagate to the caller. Would need
1062 * the bdrv_set_key() API signature to be fixed. */
1069 /* We have no actual commit/abort logic for qcow2, but we need to write out any
1070 * unwritten data if we reopen read-only. */
1071 static int qcow2_reopen_prepare(BDRVReopenState *state,
1072 BlockReopenQueue *queue, Error **errp)
1076 if ((state->flags & BDRV_O_RDWR) == 0) {
1077 ret = bdrv_flush(state->bs);
1082 ret = qcow2_mark_clean(state->bs);
1091 static int64_t coroutine_fn qcow2_co_get_block_status(BlockDriverState *bs,
1092 int64_t sector_num, int nb_sectors, int *pnum)
1094 BDRVQcowState *s = bs->opaque;
1095 uint64_t cluster_offset;
1096 int index_in_cluster, ret;
1100 qemu_co_mutex_lock(&s->lock);
1101 ret = qcow2_get_cluster_offset(bs, sector_num << 9, pnum, &cluster_offset);
1102 qemu_co_mutex_unlock(&s->lock);
1107 if (cluster_offset != 0 && ret != QCOW2_CLUSTER_COMPRESSED &&
1109 index_in_cluster = sector_num & (s->cluster_sectors - 1);
1110 cluster_offset |= (index_in_cluster << BDRV_SECTOR_BITS);
1111 status |= BDRV_BLOCK_OFFSET_VALID | cluster_offset;
1113 if (ret == QCOW2_CLUSTER_ZERO) {
1114 status |= BDRV_BLOCK_ZERO;
1115 } else if (ret != QCOW2_CLUSTER_UNALLOCATED) {
1116 status |= BDRV_BLOCK_DATA;
1121 /* handle reading after the end of the backing file */
1122 int qcow2_backing_read1(BlockDriverState *bs, QEMUIOVector *qiov,
1123 int64_t sector_num, int nb_sectors)
1126 if ((sector_num + nb_sectors) <= bs->total_sectors)
1128 if (sector_num >= bs->total_sectors)
1131 n1 = bs->total_sectors - sector_num;
1133 qemu_iovec_memset(qiov, 512 * n1, 0, 512 * (nb_sectors - n1));
1138 static coroutine_fn int qcow2_co_readv(BlockDriverState *bs, int64_t sector_num,
1139 int remaining_sectors, QEMUIOVector *qiov)
1141 BDRVQcowState *s = bs->opaque;
1142 int index_in_cluster, n1;
1144 int cur_nr_sectors; /* number of sectors in current iteration */
1145 uint64_t cluster_offset = 0;
1146 uint64_t bytes_done = 0;
1147 QEMUIOVector hd_qiov;
1148 uint8_t *cluster_data = NULL;
1150 qemu_iovec_init(&hd_qiov, qiov->niov);
1152 qemu_co_mutex_lock(&s->lock);
1154 while (remaining_sectors != 0) {
1156 /* prepare next request */
1157 cur_nr_sectors = remaining_sectors;
1159 cur_nr_sectors = MIN(cur_nr_sectors,
1160 QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors);
1163 ret = qcow2_get_cluster_offset(bs, sector_num << 9,
1164 &cur_nr_sectors, &cluster_offset);
1169 index_in_cluster = sector_num & (s->cluster_sectors - 1);
1171 qemu_iovec_reset(&hd_qiov);
1172 qemu_iovec_concat(&hd_qiov, qiov, bytes_done,
1173 cur_nr_sectors * 512);
1176 case QCOW2_CLUSTER_UNALLOCATED:
1178 if (bs->backing_hd) {
1179 /* read from the base image */
1180 n1 = qcow2_backing_read1(bs->backing_hd, &hd_qiov,
1181 sector_num, cur_nr_sectors);
1183 QEMUIOVector local_qiov;
1185 qemu_iovec_init(&local_qiov, hd_qiov.niov);
1186 qemu_iovec_concat(&local_qiov, &hd_qiov, 0,
1187 n1 * BDRV_SECTOR_SIZE);
1189 BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
1190 qemu_co_mutex_unlock(&s->lock);
1191 ret = bdrv_co_readv(bs->backing_hd, sector_num,
1193 qemu_co_mutex_lock(&s->lock);
1195 qemu_iovec_destroy(&local_qiov);
1202 /* Note: in this case, no need to wait */
1203 qemu_iovec_memset(&hd_qiov, 0, 0, 512 * cur_nr_sectors);
1207 case QCOW2_CLUSTER_ZERO:
1208 qemu_iovec_memset(&hd_qiov, 0, 0, 512 * cur_nr_sectors);
1211 case QCOW2_CLUSTER_COMPRESSED:
1212 /* add AIO support for compressed blocks ? */
1213 ret = qcow2_decompress_cluster(bs, cluster_offset);
1218 qemu_iovec_from_buf(&hd_qiov, 0,
1219 s->cluster_cache + index_in_cluster * 512,
1220 512 * cur_nr_sectors);
1223 case QCOW2_CLUSTER_NORMAL:
1224 if ((cluster_offset & 511) != 0) {
1229 if (bs->encrypted) {
1233 * For encrypted images, read everything into a temporary
1234 * contiguous buffer on which the AES functions can work.
1236 if (!cluster_data) {
1238 qemu_try_blockalign(bs->file, QCOW_MAX_CRYPT_CLUSTERS
1240 if (cluster_data == NULL) {
1246 assert(cur_nr_sectors <=
1247 QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors);
1248 qemu_iovec_reset(&hd_qiov);
1249 qemu_iovec_add(&hd_qiov, cluster_data,
1250 512 * cur_nr_sectors);
1253 BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
1254 qemu_co_mutex_unlock(&s->lock);
1255 ret = bdrv_co_readv(bs->file,
1256 (cluster_offset >> 9) + index_in_cluster,
1257 cur_nr_sectors, &hd_qiov);
1258 qemu_co_mutex_lock(&s->lock);
1262 if (bs->encrypted) {
1265 if (qcow2_encrypt_sectors(s, sector_num, cluster_data,
1266 cluster_data, cur_nr_sectors, false,
1272 qemu_iovec_from_buf(qiov, bytes_done,
1273 cluster_data, 512 * cur_nr_sectors);
1278 g_assert_not_reached();
1283 remaining_sectors -= cur_nr_sectors;
1284 sector_num += cur_nr_sectors;
1285 bytes_done += cur_nr_sectors * 512;
1290 qemu_co_mutex_unlock(&s->lock);
1292 qemu_iovec_destroy(&hd_qiov);
1293 qemu_vfree(cluster_data);
1298 static coroutine_fn int qcow2_co_writev(BlockDriverState *bs,
1300 int remaining_sectors,
1303 BDRVQcowState *s = bs->opaque;
1304 int index_in_cluster;
1306 int cur_nr_sectors; /* number of sectors in current iteration */
1307 uint64_t cluster_offset;
1308 QEMUIOVector hd_qiov;
1309 uint64_t bytes_done = 0;
1310 uint8_t *cluster_data = NULL;
1311 QCowL2Meta *l2meta = NULL;
1313 trace_qcow2_writev_start_req(qemu_coroutine_self(), sector_num,
1316 qemu_iovec_init(&hd_qiov, qiov->niov);
1318 s->cluster_cache_offset = -1; /* disable compressed cache */
1320 qemu_co_mutex_lock(&s->lock);
1322 while (remaining_sectors != 0) {
1326 trace_qcow2_writev_start_part(qemu_coroutine_self());
1327 index_in_cluster = sector_num & (s->cluster_sectors - 1);
1328 cur_nr_sectors = remaining_sectors;
1329 if (bs->encrypted &&
1331 QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors - index_in_cluster) {
1333 QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors - index_in_cluster;
1336 ret = qcow2_alloc_cluster_offset(bs, sector_num << 9,
1337 &cur_nr_sectors, &cluster_offset, &l2meta);
1342 assert((cluster_offset & 511) == 0);
1344 qemu_iovec_reset(&hd_qiov);
1345 qemu_iovec_concat(&hd_qiov, qiov, bytes_done,
1346 cur_nr_sectors * 512);
1348 if (bs->encrypted) {
1351 if (!cluster_data) {
1352 cluster_data = qemu_try_blockalign(bs->file,
1353 QCOW_MAX_CRYPT_CLUSTERS
1355 if (cluster_data == NULL) {
1361 assert(hd_qiov.size <=
1362 QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
1363 qemu_iovec_to_buf(&hd_qiov, 0, cluster_data, hd_qiov.size);
1365 if (qcow2_encrypt_sectors(s, sector_num, cluster_data,
1366 cluster_data, cur_nr_sectors,
1373 qemu_iovec_reset(&hd_qiov);
1374 qemu_iovec_add(&hd_qiov, cluster_data,
1375 cur_nr_sectors * 512);
1378 ret = qcow2_pre_write_overlap_check(bs, 0,
1379 cluster_offset + index_in_cluster * BDRV_SECTOR_SIZE,
1380 cur_nr_sectors * BDRV_SECTOR_SIZE);
1385 qemu_co_mutex_unlock(&s->lock);
1386 BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
1387 trace_qcow2_writev_data(qemu_coroutine_self(),
1388 (cluster_offset >> 9) + index_in_cluster);
1389 ret = bdrv_co_writev(bs->file,
1390 (cluster_offset >> 9) + index_in_cluster,
1391 cur_nr_sectors, &hd_qiov);
1392 qemu_co_mutex_lock(&s->lock);
1397 while (l2meta != NULL) {
1400 ret = qcow2_alloc_cluster_link_l2(bs, l2meta);
1405 /* Take the request off the list of running requests */
1406 if (l2meta->nb_clusters != 0) {
1407 QLIST_REMOVE(l2meta, next_in_flight);
1410 qemu_co_queue_restart_all(&l2meta->dependent_requests);
1412 next = l2meta->next;
1417 remaining_sectors -= cur_nr_sectors;
1418 sector_num += cur_nr_sectors;
1419 bytes_done += cur_nr_sectors * 512;
1420 trace_qcow2_writev_done_part(qemu_coroutine_self(), cur_nr_sectors);
1425 qemu_co_mutex_unlock(&s->lock);
1427 while (l2meta != NULL) {
1430 if (l2meta->nb_clusters != 0) {
1431 QLIST_REMOVE(l2meta, next_in_flight);
1433 qemu_co_queue_restart_all(&l2meta->dependent_requests);
1435 next = l2meta->next;
1440 qemu_iovec_destroy(&hd_qiov);
1441 qemu_vfree(cluster_data);
1442 trace_qcow2_writev_done_req(qemu_coroutine_self(), ret);
1447 static void qcow2_close(BlockDriverState *bs)
1449 BDRVQcowState *s = bs->opaque;
1450 qemu_vfree(s->l1_table);
1451 /* else pre-write overlap checks in cache_destroy may crash */
1454 if (!(bs->open_flags & BDRV_O_INCOMING)) {
1457 ret1 = qcow2_cache_flush(bs, s->l2_table_cache);
1458 ret2 = qcow2_cache_flush(bs, s->refcount_block_cache);
1461 error_report("Failed to flush the L2 table cache: %s",
1465 error_report("Failed to flush the refcount block cache: %s",
1469 if (!ret1 && !ret2) {
1470 qcow2_mark_clean(bs);
1474 qcow2_cache_destroy(bs, s->l2_table_cache);
1475 qcow2_cache_destroy(bs, s->refcount_block_cache);
1477 qcrypto_cipher_free(s->cipher);
1480 g_free(s->unknown_header_fields);
1481 cleanup_unknown_header_ext(bs);
1483 g_free(s->image_backing_file);
1484 g_free(s->image_backing_format);
1486 g_free(s->cluster_cache);
1487 qemu_vfree(s->cluster_data);
1488 qcow2_refcount_close(bs);
1489 qcow2_free_snapshots(bs);
1492 static void qcow2_invalidate_cache(BlockDriverState *bs, Error **errp)
1494 BDRVQcowState *s = bs->opaque;
1495 int flags = s->flags;
1496 QCryptoCipher *cipher = NULL;
1498 Error *local_err = NULL;
1502 * Backing files are read-only which makes all of their metadata immutable,
1503 * that means we don't have to worry about reopening them here.
1511 bdrv_invalidate_cache(bs->file, &local_err);
1513 error_propagate(errp, local_err);
1517 memset(s, 0, sizeof(BDRVQcowState));
1518 options = qdict_clone_shallow(bs->options);
1520 ret = qcow2_open(bs, options, flags, &local_err);
1523 error_setg(errp, "Could not reopen qcow2 layer: %s",
1524 error_get_pretty(local_err));
1525 error_free(local_err);
1527 } else if (ret < 0) {
1528 error_setg_errno(errp, -ret, "Could not reopen qcow2 layer");
1535 static size_t header_ext_add(char *buf, uint32_t magic, const void *s,
1536 size_t len, size_t buflen)
1538 QCowExtension *ext_backing_fmt = (QCowExtension*) buf;
1539 size_t ext_len = sizeof(QCowExtension) + ((len + 7) & ~7);
1541 if (buflen < ext_len) {
1545 *ext_backing_fmt = (QCowExtension) {
1546 .magic = cpu_to_be32(magic),
1547 .len = cpu_to_be32(len),
1549 memcpy(buf + sizeof(QCowExtension), s, len);
1555 * Updates the qcow2 header, including the variable length parts of it, i.e.
1556 * the backing file name and all extensions. qcow2 was not designed to allow
1557 * such changes, so if we run out of space (we can only use the first cluster)
1558 * this function may fail.
1560 * Returns 0 on success, -errno in error cases.
1562 int qcow2_update_header(BlockDriverState *bs)
1564 BDRVQcowState *s = bs->opaque;
1567 size_t buflen = s->cluster_size;
1569 uint64_t total_size;
1570 uint32_t refcount_table_clusters;
1571 size_t header_length;
1572 Qcow2UnknownHeaderExtension *uext;
1574 buf = qemu_blockalign(bs, buflen);
1576 /* Header structure */
1577 header = (QCowHeader*) buf;
1579 if (buflen < sizeof(*header)) {
1584 header_length = sizeof(*header) + s->unknown_header_fields_size;
1585 total_size = bs->total_sectors * BDRV_SECTOR_SIZE;
1586 refcount_table_clusters = s->refcount_table_size >> (s->cluster_bits - 3);
1588 *header = (QCowHeader) {
1589 /* Version 2 fields */
1590 .magic = cpu_to_be32(QCOW_MAGIC),
1591 .version = cpu_to_be32(s->qcow_version),
1592 .backing_file_offset = 0,
1593 .backing_file_size = 0,
1594 .cluster_bits = cpu_to_be32(s->cluster_bits),
1595 .size = cpu_to_be64(total_size),
1596 .crypt_method = cpu_to_be32(s->crypt_method_header),
1597 .l1_size = cpu_to_be32(s->l1_size),
1598 .l1_table_offset = cpu_to_be64(s->l1_table_offset),
1599 .refcount_table_offset = cpu_to_be64(s->refcount_table_offset),
1600 .refcount_table_clusters = cpu_to_be32(refcount_table_clusters),
1601 .nb_snapshots = cpu_to_be32(s->nb_snapshots),
1602 .snapshots_offset = cpu_to_be64(s->snapshots_offset),
1604 /* Version 3 fields */
1605 .incompatible_features = cpu_to_be64(s->incompatible_features),
1606 .compatible_features = cpu_to_be64(s->compatible_features),
1607 .autoclear_features = cpu_to_be64(s->autoclear_features),
1608 .refcount_order = cpu_to_be32(s->refcount_order),
1609 .header_length = cpu_to_be32(header_length),
1612 /* For older versions, write a shorter header */
1613 switch (s->qcow_version) {
1615 ret = offsetof(QCowHeader, incompatible_features);
1618 ret = sizeof(*header);
1627 memset(buf, 0, buflen);
1629 /* Preserve any unknown field in the header */
1630 if (s->unknown_header_fields_size) {
1631 if (buflen < s->unknown_header_fields_size) {
1636 memcpy(buf, s->unknown_header_fields, s->unknown_header_fields_size);
1637 buf += s->unknown_header_fields_size;
1638 buflen -= s->unknown_header_fields_size;
1641 /* Backing file format header extension */
1642 if (s->image_backing_format) {
1643 ret = header_ext_add(buf, QCOW2_EXT_MAGIC_BACKING_FORMAT,
1644 s->image_backing_format,
1645 strlen(s->image_backing_format),
1656 Qcow2Feature features[] = {
1658 .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
1659 .bit = QCOW2_INCOMPAT_DIRTY_BITNR,
1660 .name = "dirty bit",
1663 .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
1664 .bit = QCOW2_INCOMPAT_CORRUPT_BITNR,
1665 .name = "corrupt bit",
1668 .type = QCOW2_FEAT_TYPE_COMPATIBLE,
1669 .bit = QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR,
1670 .name = "lazy refcounts",
1674 ret = header_ext_add(buf, QCOW2_EXT_MAGIC_FEATURE_TABLE,
1675 features, sizeof(features), buflen);
1682 /* Keep unknown header extensions */
1683 QLIST_FOREACH(uext, &s->unknown_header_ext, next) {
1684 ret = header_ext_add(buf, uext->magic, uext->data, uext->len, buflen);
1693 /* End of header extensions */
1694 ret = header_ext_add(buf, QCOW2_EXT_MAGIC_END, NULL, 0, buflen);
1702 /* Backing file name */
1703 if (s->image_backing_file) {
1704 size_t backing_file_len = strlen(s->image_backing_file);
1706 if (buflen < backing_file_len) {
1711 /* Using strncpy is ok here, since buf is not NUL-terminated. */
1712 strncpy(buf, s->image_backing_file, buflen);
1714 header->backing_file_offset = cpu_to_be64(buf - ((char*) header));
1715 header->backing_file_size = cpu_to_be32(backing_file_len);
1718 /* Write the new header */
1719 ret = bdrv_pwrite(bs->file, 0, header, s->cluster_size);
1730 static int qcow2_change_backing_file(BlockDriverState *bs,
1731 const char *backing_file, const char *backing_fmt)
1733 BDRVQcowState *s = bs->opaque;
1735 pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
1736 pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");
1738 g_free(s->image_backing_file);
1739 g_free(s->image_backing_format);
1741 s->image_backing_file = backing_file ? g_strdup(bs->backing_file) : NULL;
1742 s->image_backing_format = backing_fmt ? g_strdup(bs->backing_format) : NULL;
1744 return qcow2_update_header(bs);
1747 static int preallocate(BlockDriverState *bs)
1749 uint64_t nb_sectors;
1751 uint64_t host_offset = 0;
1756 nb_sectors = bdrv_nb_sectors(bs);
1759 while (nb_sectors) {
1760 num = MIN(nb_sectors, INT_MAX >> BDRV_SECTOR_BITS);
1761 ret = qcow2_alloc_cluster_offset(bs, offset, &num,
1762 &host_offset, &meta);
1768 QCowL2Meta *next = meta->next;
1770 ret = qcow2_alloc_cluster_link_l2(bs, meta);
1772 qcow2_free_any_clusters(bs, meta->alloc_offset,
1773 meta->nb_clusters, QCOW2_DISCARD_NEVER);
1777 /* There are no dependent requests, but we need to remove our
1778 * request from the list of in-flight requests */
1779 QLIST_REMOVE(meta, next_in_flight);
1785 /* TODO Preallocate data if requested */
1788 offset += num << BDRV_SECTOR_BITS;
1792 * It is expected that the image file is large enough to actually contain
1793 * all of the allocated clusters (otherwise we get failing reads after
1794 * EOF). Extend the image to the last allocated sector.
1796 if (host_offset != 0) {
1797 uint8_t buf[BDRV_SECTOR_SIZE];
1798 memset(buf, 0, BDRV_SECTOR_SIZE);
1799 ret = bdrv_write(bs->file, (host_offset >> BDRV_SECTOR_BITS) + num - 1,
1809 static int qcow2_create2(const char *filename, int64_t total_size,
1810 const char *backing_file, const char *backing_format,
1811 int flags, size_t cluster_size, PreallocMode prealloc,
1812 QemuOpts *opts, int version, int refcount_order,
1815 /* Calculate cluster_bits */
1817 cluster_bits = ctz32(cluster_size);
1818 if (cluster_bits < MIN_CLUSTER_BITS || cluster_bits > MAX_CLUSTER_BITS ||
1819 (1 << cluster_bits) != cluster_size)
1821 error_setg(errp, "Cluster size must be a power of two between %d and "
1822 "%dk", 1 << MIN_CLUSTER_BITS, 1 << (MAX_CLUSTER_BITS - 10));
1827 * Open the image file and write a minimal qcow2 header.
1829 * We keep things simple and start with a zero-sized image. We also
1830 * do without refcount blocks or a L1 table for now. We'll fix the
1831 * inconsistency later.
1833 * We do need a refcount table because growing the refcount table means
1834 * allocating two new refcount blocks - the seconds of which would be at
1835 * 2 GB for 64k clusters, and we don't want to have a 2 GB initial file
1836 * size for any qcow2 image.
1838 BlockDriverState* bs;
1840 uint64_t* refcount_table;
1841 Error *local_err = NULL;
1844 if (prealloc == PREALLOC_MODE_FULL || prealloc == PREALLOC_MODE_FALLOC) {
1845 /* Note: The following calculation does not need to be exact; if it is a
1846 * bit off, either some bytes will be "leaked" (which is fine) or we
1847 * will need to increase the file size by some bytes (which is fine,
1848 * too, as long as the bulk is allocated here). Therefore, using
1849 * floating point arithmetic is fine. */
1850 int64_t meta_size = 0;
1851 uint64_t nreftablee, nrefblocke, nl1e, nl2e;
1852 int64_t aligned_total_size = align_offset(total_size, cluster_size);
1853 int refblock_bits, refblock_size;
1854 /* refcount entry size in bytes */
1855 double rces = (1 << refcount_order) / 8.;
1857 /* see qcow2_open() */
1858 refblock_bits = cluster_bits - (refcount_order - 3);
1859 refblock_size = 1 << refblock_bits;
1861 /* header: 1 cluster */
1862 meta_size += cluster_size;
1864 /* total size of L2 tables */
1865 nl2e = aligned_total_size / cluster_size;
1866 nl2e = align_offset(nl2e, cluster_size / sizeof(uint64_t));
1867 meta_size += nl2e * sizeof(uint64_t);
1869 /* total size of L1 tables */
1870 nl1e = nl2e * sizeof(uint64_t) / cluster_size;
1871 nl1e = align_offset(nl1e, cluster_size / sizeof(uint64_t));
1872 meta_size += nl1e * sizeof(uint64_t);
1874 /* total size of refcount blocks
1876 * note: every host cluster is reference-counted, including metadata
1877 * (even refcount blocks are recursively included).
1879 * a = total_size (this is the guest disk size)
1880 * m = meta size not including refcount blocks and refcount tables
1882 * y1 = number of refcount blocks entries
1883 * y2 = meta size including everything
1884 * rces = refcount entry size in bytes
1887 * y2 = y1 * rces + y1 * rces * sizeof(u64) / c + m
1889 * y1 = (a + m) / (c - rces - rces * sizeof(u64) / c)
1891 nrefblocke = (aligned_total_size + meta_size + cluster_size)
1892 / (cluster_size - rces - rces * sizeof(uint64_t)
1894 meta_size += DIV_ROUND_UP(nrefblocke, refblock_size) * cluster_size;
1896 /* total size of refcount tables */
1897 nreftablee = nrefblocke / refblock_size;
1898 nreftablee = align_offset(nreftablee, cluster_size / sizeof(uint64_t));
1899 meta_size += nreftablee * sizeof(uint64_t);
1901 qemu_opt_set_number(opts, BLOCK_OPT_SIZE,
1902 aligned_total_size + meta_size, &error_abort);
1903 qemu_opt_set(opts, BLOCK_OPT_PREALLOC, PreallocMode_lookup[prealloc],
1907 ret = bdrv_create_file(filename, opts, &local_err);
1909 error_propagate(errp, local_err);
1914 ret = bdrv_open(&bs, filename, NULL, NULL, BDRV_O_RDWR | BDRV_O_PROTOCOL,
1917 error_propagate(errp, local_err);
1921 /* Write the header */
1922 QEMU_BUILD_BUG_ON((1 << MIN_CLUSTER_BITS) < sizeof(*header));
1923 header = g_malloc0(cluster_size);
1924 *header = (QCowHeader) {
1925 .magic = cpu_to_be32(QCOW_MAGIC),
1926 .version = cpu_to_be32(version),
1927 .cluster_bits = cpu_to_be32(cluster_bits),
1928 .size = cpu_to_be64(0),
1929 .l1_table_offset = cpu_to_be64(0),
1930 .l1_size = cpu_to_be32(0),
1931 .refcount_table_offset = cpu_to_be64(cluster_size),
1932 .refcount_table_clusters = cpu_to_be32(1),
1933 .refcount_order = cpu_to_be32(refcount_order),
1934 .header_length = cpu_to_be32(sizeof(*header)),
1937 if (flags & BLOCK_FLAG_ENCRYPT) {
1938 header->crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
1940 header->crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
1943 if (flags & BLOCK_FLAG_LAZY_REFCOUNTS) {
1944 header->compatible_features |=
1945 cpu_to_be64(QCOW2_COMPAT_LAZY_REFCOUNTS);
1948 ret = bdrv_pwrite(bs, 0, header, cluster_size);
1951 error_setg_errno(errp, -ret, "Could not write qcow2 header");
1955 /* Write a refcount table with one refcount block */
1956 refcount_table = g_malloc0(2 * cluster_size);
1957 refcount_table[0] = cpu_to_be64(2 * cluster_size);
1958 ret = bdrv_pwrite(bs, cluster_size, refcount_table, 2 * cluster_size);
1959 g_free(refcount_table);
1962 error_setg_errno(errp, -ret, "Could not write refcount table");
1970 * And now open the image and make it consistent first (i.e. increase the
1971 * refcount of the cluster that is occupied by the header and the refcount
1974 ret = bdrv_open(&bs, filename, NULL, NULL,
1975 BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH,
1976 &bdrv_qcow2, &local_err);
1978 error_propagate(errp, local_err);
1982 ret = qcow2_alloc_clusters(bs, 3 * cluster_size);
1984 error_setg_errno(errp, -ret, "Could not allocate clusters for qcow2 "
1985 "header and refcount table");
1988 } else if (ret != 0) {
1989 error_report("Huh, first cluster in empty image is already in use?");
1993 /* Okay, now that we have a valid image, let's give it the right size */
1994 ret = bdrv_truncate(bs, total_size);
1996 error_setg_errno(errp, -ret, "Could not resize image");
2000 /* Want a backing file? There you go.*/
2002 ret = bdrv_change_backing_file(bs, backing_file, backing_format);
2004 error_setg_errno(errp, -ret, "Could not assign backing file '%s' "
2005 "with format '%s'", backing_file, backing_format);
2010 /* And if we're supposed to preallocate metadata, do that now */
2011 if (prealloc != PREALLOC_MODE_OFF) {
2012 BDRVQcowState *s = bs->opaque;
2013 qemu_co_mutex_lock(&s->lock);
2014 ret = preallocate(bs);
2015 qemu_co_mutex_unlock(&s->lock);
2017 error_setg_errno(errp, -ret, "Could not preallocate metadata");
2025 /* Reopen the image without BDRV_O_NO_FLUSH to flush it before returning */
2026 ret = bdrv_open(&bs, filename, NULL, NULL,
2027 BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_BACKING,
2028 &bdrv_qcow2, &local_err);
2030 error_propagate(errp, local_err);
2042 static int qcow2_create(const char *filename, QemuOpts *opts, Error **errp)
2044 char *backing_file = NULL;
2045 char *backing_fmt = NULL;
2049 size_t cluster_size = DEFAULT_CLUSTER_SIZE;
2050 PreallocMode prealloc;
2052 uint64_t refcount_bits = 16;
2054 Error *local_err = NULL;
2057 /* Read out options */
2058 size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
2060 backing_file = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FILE);
2061 backing_fmt = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FMT);
2062 if (qemu_opt_get_bool_del(opts, BLOCK_OPT_ENCRYPT, false)) {
2063 flags |= BLOCK_FLAG_ENCRYPT;
2065 cluster_size = qemu_opt_get_size_del(opts, BLOCK_OPT_CLUSTER_SIZE,
2066 DEFAULT_CLUSTER_SIZE);
2067 buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
2068 prealloc = qapi_enum_parse(PreallocMode_lookup, buf,
2069 PREALLOC_MODE_MAX, PREALLOC_MODE_OFF,
2072 error_propagate(errp, local_err);
2077 buf = qemu_opt_get_del(opts, BLOCK_OPT_COMPAT_LEVEL);
2079 /* keep the default */
2080 } else if (!strcmp(buf, "0.10")) {
2082 } else if (!strcmp(buf, "1.1")) {
2085 error_setg(errp, "Invalid compatibility level: '%s'", buf);
2090 if (qemu_opt_get_bool_del(opts, BLOCK_OPT_LAZY_REFCOUNTS, false)) {
2091 flags |= BLOCK_FLAG_LAZY_REFCOUNTS;
2094 if (backing_file && prealloc != PREALLOC_MODE_OFF) {
2095 error_setg(errp, "Backing file and preallocation cannot be used at "
2101 if (version < 3 && (flags & BLOCK_FLAG_LAZY_REFCOUNTS)) {
2102 error_setg(errp, "Lazy refcounts only supported with compatibility "
2103 "level 1.1 and above (use compat=1.1 or greater)");
2108 refcount_bits = qemu_opt_get_number_del(opts, BLOCK_OPT_REFCOUNT_BITS,
2110 if (refcount_bits > 64 || !is_power_of_2(refcount_bits)) {
2111 error_setg(errp, "Refcount width must be a power of two and may not "
2117 if (version < 3 && refcount_bits != 16) {
2118 error_setg(errp, "Different refcount widths than 16 bits require "
2119 "compatibility level 1.1 or above (use compat=1.1 or "
2125 refcount_order = ctz32(refcount_bits);
2127 ret = qcow2_create2(filename, size, backing_file, backing_fmt, flags,
2128 cluster_size, prealloc, opts, version, refcount_order,
2131 error_propagate(errp, local_err);
2135 g_free(backing_file);
2136 g_free(backing_fmt);
2141 static coroutine_fn int qcow2_co_write_zeroes(BlockDriverState *bs,
2142 int64_t sector_num, int nb_sectors, BdrvRequestFlags flags)
2145 BDRVQcowState *s = bs->opaque;
2147 /* Emulate misaligned zero writes */
2148 if (sector_num % s->cluster_sectors || nb_sectors % s->cluster_sectors) {
2152 /* Whatever is left can use real zero clusters */
2153 qemu_co_mutex_lock(&s->lock);
2154 ret = qcow2_zero_clusters(bs, sector_num << BDRV_SECTOR_BITS,
2156 qemu_co_mutex_unlock(&s->lock);
2161 static coroutine_fn int qcow2_co_discard(BlockDriverState *bs,
2162 int64_t sector_num, int nb_sectors)
2165 BDRVQcowState *s = bs->opaque;
2167 qemu_co_mutex_lock(&s->lock);
2168 ret = qcow2_discard_clusters(bs, sector_num << BDRV_SECTOR_BITS,
2169 nb_sectors, QCOW2_DISCARD_REQUEST, false);
2170 qemu_co_mutex_unlock(&s->lock);
2174 static int qcow2_truncate(BlockDriverState *bs, int64_t offset)
2176 BDRVQcowState *s = bs->opaque;
2177 int64_t new_l1_size;
2181 error_report("The new size must be a multiple of 512");
2185 /* cannot proceed if image has snapshots */
2186 if (s->nb_snapshots) {
2187 error_report("Can't resize an image which has snapshots");
2191 /* shrinking is currently not supported */
2192 if (offset < bs->total_sectors * 512) {
2193 error_report("qcow2 doesn't support shrinking images yet");
2197 new_l1_size = size_to_l1(s, offset);
2198 ret = qcow2_grow_l1_table(bs, new_l1_size, true);
2203 /* write updated header.size */
2204 offset = cpu_to_be64(offset);
2205 ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, size),
2206 &offset, sizeof(uint64_t));
2211 s->l1_vm_state_index = new_l1_size;
2215 /* XXX: put compressed sectors first, then all the cluster aligned
2216 tables to avoid losing bytes in alignment */
2217 static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num,
2218 const uint8_t *buf, int nb_sectors)
2220 BDRVQcowState *s = bs->opaque;
2224 uint64_t cluster_offset;
2226 if (nb_sectors == 0) {
2227 /* align end of file to a sector boundary to ease reading with
2228 sector based I/Os */
2229 cluster_offset = bdrv_getlength(bs->file);
2230 return bdrv_truncate(bs->file, cluster_offset);
2233 if (nb_sectors != s->cluster_sectors) {
2236 /* Zero-pad last write if image size is not cluster aligned */
2237 if (sector_num + nb_sectors == bs->total_sectors &&
2238 nb_sectors < s->cluster_sectors) {
2239 uint8_t *pad_buf = qemu_blockalign(bs, s->cluster_size);
2240 memset(pad_buf, 0, s->cluster_size);
2241 memcpy(pad_buf, buf, nb_sectors * BDRV_SECTOR_SIZE);
2242 ret = qcow2_write_compressed(bs, sector_num,
2243 pad_buf, s->cluster_sectors);
2244 qemu_vfree(pad_buf);
2249 out_buf = g_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
2251 /* best compression, small window, no zlib header */
2252 memset(&strm, 0, sizeof(strm));
2253 ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
2255 9, Z_DEFAULT_STRATEGY);
2261 strm.avail_in = s->cluster_size;
2262 strm.next_in = (uint8_t *)buf;
2263 strm.avail_out = s->cluster_size;
2264 strm.next_out = out_buf;
2266 ret = deflate(&strm, Z_FINISH);
2267 if (ret != Z_STREAM_END && ret != Z_OK) {
2272 out_len = strm.next_out - out_buf;
2276 if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
2277 /* could not compress: write normal cluster */
2278 ret = bdrv_write(bs, sector_num, buf, s->cluster_sectors);
2283 cluster_offset = qcow2_alloc_compressed_cluster_offset(bs,
2284 sector_num << 9, out_len);
2285 if (!cluster_offset) {
2289 cluster_offset &= s->cluster_offset_mask;
2291 ret = qcow2_pre_write_overlap_check(bs, 0, cluster_offset, out_len);
2296 BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED);
2297 ret = bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len);
2309 static int make_completely_empty(BlockDriverState *bs)
2311 BDRVQcowState *s = bs->opaque;
2312 int ret, l1_clusters;
2314 uint64_t *new_reftable = NULL;
2315 uint64_t rt_entry, l1_size2;
2318 uint64_t reftable_offset;
2319 uint32_t reftable_clusters;
2320 } QEMU_PACKED l1_ofs_rt_ofs_cls;
2322 ret = qcow2_cache_empty(bs, s->l2_table_cache);
2327 ret = qcow2_cache_empty(bs, s->refcount_block_cache);
2332 /* Refcounts will be broken utterly */
2333 ret = qcow2_mark_dirty(bs);
2338 BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE);
2340 l1_clusters = DIV_ROUND_UP(s->l1_size, s->cluster_size / sizeof(uint64_t));
2341 l1_size2 = (uint64_t)s->l1_size * sizeof(uint64_t);
2343 /* After this call, neither the in-memory nor the on-disk refcount
2344 * information accurately describe the actual references */
2346 ret = bdrv_write_zeroes(bs->file, s->l1_table_offset / BDRV_SECTOR_SIZE,
2347 l1_clusters * s->cluster_sectors, 0);
2349 goto fail_broken_refcounts;
2351 memset(s->l1_table, 0, l1_size2);
2353 BLKDBG_EVENT(bs->file, BLKDBG_EMPTY_IMAGE_PREPARE);
2355 /* Overwrite enough clusters at the beginning of the sectors to place
2356 * the refcount table, a refcount block and the L1 table in; this may
2357 * overwrite parts of the existing refcount and L1 table, which is not
2358 * an issue because the dirty flag is set, complete data loss is in fact
2359 * desired and partial data loss is consequently fine as well */
2360 ret = bdrv_write_zeroes(bs->file, s->cluster_size / BDRV_SECTOR_SIZE,
2361 (2 + l1_clusters) * s->cluster_size /
2362 BDRV_SECTOR_SIZE, 0);
2363 /* This call (even if it failed overall) may have overwritten on-disk
2364 * refcount structures; in that case, the in-memory refcount information
2365 * will probably differ from the on-disk information which makes the BDS
2368 goto fail_broken_refcounts;
2371 BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE);
2372 BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_UPDATE);
2374 /* "Create" an empty reftable (one cluster) directly after the image
2375 * header and an empty L1 table three clusters after the image header;
2376 * the cluster between those two will be used as the first refblock */
2377 cpu_to_be64w(&l1_ofs_rt_ofs_cls.l1_offset, 3 * s->cluster_size);
2378 cpu_to_be64w(&l1_ofs_rt_ofs_cls.reftable_offset, s->cluster_size);
2379 cpu_to_be32w(&l1_ofs_rt_ofs_cls.reftable_clusters, 1);
2380 ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, l1_table_offset),
2381 &l1_ofs_rt_ofs_cls, sizeof(l1_ofs_rt_ofs_cls));
2383 goto fail_broken_refcounts;
2386 s->l1_table_offset = 3 * s->cluster_size;
2388 new_reftable = g_try_new0(uint64_t, s->cluster_size / sizeof(uint64_t));
2389 if (!new_reftable) {
2391 goto fail_broken_refcounts;
2394 s->refcount_table_offset = s->cluster_size;
2395 s->refcount_table_size = s->cluster_size / sizeof(uint64_t);
2397 g_free(s->refcount_table);
2398 s->refcount_table = new_reftable;
2399 new_reftable = NULL;
2401 /* Now the in-memory refcount information again corresponds to the on-disk
2402 * information (reftable is empty and no refblocks (the refblock cache is
2403 * empty)); however, this means some clusters (e.g. the image header) are
2404 * referenced, but not refcounted, but the normal qcow2 code assumes that
2405 * the in-memory information is always correct */
2407 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC);
2409 /* Enter the first refblock into the reftable */
2410 rt_entry = cpu_to_be64(2 * s->cluster_size);
2411 ret = bdrv_pwrite_sync(bs->file, s->cluster_size,
2412 &rt_entry, sizeof(rt_entry));
2414 goto fail_broken_refcounts;
2416 s->refcount_table[0] = 2 * s->cluster_size;
2418 s->free_cluster_index = 0;
2419 assert(3 + l1_clusters <= s->refcount_block_size);
2420 offset = qcow2_alloc_clusters(bs, 3 * s->cluster_size + l1_size2);
2423 goto fail_broken_refcounts;
2424 } else if (offset > 0) {
2425 error_report("First cluster in emptied image is in use");
2429 /* Now finally the in-memory information corresponds to the on-disk
2430 * structures and is correct */
2431 ret = qcow2_mark_clean(bs);
2436 ret = bdrv_truncate(bs->file, (3 + l1_clusters) * s->cluster_size);
2443 fail_broken_refcounts:
2444 /* The BDS is unusable at this point. If we wanted to make it usable, we
2445 * would have to call qcow2_refcount_close(), qcow2_refcount_init(),
2446 * qcow2_check_refcounts(), qcow2_refcount_close() and qcow2_refcount_init()
2447 * again. However, because the functions which could have caused this error
2448 * path to be taken are used by those functions as well, it's very likely
2449 * that that sequence will fail as well. Therefore, just eject the BDS. */
2453 g_free(new_reftable);
2457 static int qcow2_make_empty(BlockDriverState *bs)
2459 BDRVQcowState *s = bs->opaque;
2460 uint64_t start_sector;
2461 int sector_step = INT_MAX / BDRV_SECTOR_SIZE;
2462 int l1_clusters, ret = 0;
2464 l1_clusters = DIV_ROUND_UP(s->l1_size, s->cluster_size / sizeof(uint64_t));
2466 if (s->qcow_version >= 3 && !s->snapshots &&
2467 3 + l1_clusters <= s->refcount_block_size) {
2468 /* The following function only works for qcow2 v3 images (it requires
2469 * the dirty flag) and only as long as there are no snapshots (because
2470 * it completely empties the image). Furthermore, the L1 table and three
2471 * additional clusters (image header, refcount table, one refcount
2472 * block) have to fit inside one refcount block. */
2473 return make_completely_empty(bs);
2476 /* This fallback code simply discards every active cluster; this is slow,
2477 * but works in all cases */
2478 for (start_sector = 0; start_sector < bs->total_sectors;
2479 start_sector += sector_step)
2481 /* As this function is generally used after committing an external
2482 * snapshot, QCOW2_DISCARD_SNAPSHOT seems appropriate. Also, the
2483 * default action for this kind of discard is to pass the discard,
2484 * which will ideally result in an actually smaller image file, as
2485 * is probably desired. */
2486 ret = qcow2_discard_clusters(bs, start_sector * BDRV_SECTOR_SIZE,
2488 bs->total_sectors - start_sector),
2489 QCOW2_DISCARD_SNAPSHOT, true);
2498 static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs)
2500 BDRVQcowState *s = bs->opaque;
2503 qemu_co_mutex_lock(&s->lock);
2504 ret = qcow2_cache_flush(bs, s->l2_table_cache);
2506 qemu_co_mutex_unlock(&s->lock);
2510 if (qcow2_need_accurate_refcounts(s)) {
2511 ret = qcow2_cache_flush(bs, s->refcount_block_cache);
2513 qemu_co_mutex_unlock(&s->lock);
2517 qemu_co_mutex_unlock(&s->lock);
2522 static int qcow2_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
2524 BDRVQcowState *s = bs->opaque;
2525 bdi->unallocated_blocks_are_zero = true;
2526 bdi->can_write_zeroes_with_unmap = (s->qcow_version >= 3);
2527 bdi->cluster_size = s->cluster_size;
2528 bdi->vm_state_offset = qcow2_vm_state_offset(s);
2532 static ImageInfoSpecific *qcow2_get_specific_info(BlockDriverState *bs)
2534 BDRVQcowState *s = bs->opaque;
2535 ImageInfoSpecific *spec_info = g_new(ImageInfoSpecific, 1);
2537 *spec_info = (ImageInfoSpecific){
2538 .kind = IMAGE_INFO_SPECIFIC_KIND_QCOW2,
2540 .qcow2 = g_new(ImageInfoSpecificQCow2, 1),
2543 if (s->qcow_version == 2) {
2544 *spec_info->qcow2 = (ImageInfoSpecificQCow2){
2545 .compat = g_strdup("0.10"),
2546 .refcount_bits = s->refcount_bits,
2548 } else if (s->qcow_version == 3) {
2549 *spec_info->qcow2 = (ImageInfoSpecificQCow2){
2550 .compat = g_strdup("1.1"),
2551 .lazy_refcounts = s->compatible_features &
2552 QCOW2_COMPAT_LAZY_REFCOUNTS,
2553 .has_lazy_refcounts = true,
2554 .corrupt = s->incompatible_features &
2555 QCOW2_INCOMPAT_CORRUPT,
2556 .has_corrupt = true,
2557 .refcount_bits = s->refcount_bits,
2565 static void dump_refcounts(BlockDriverState *bs)
2567 BDRVQcowState *s = bs->opaque;
2568 int64_t nb_clusters, k, k1, size;
2571 size = bdrv_getlength(bs->file);
2572 nb_clusters = size_to_clusters(s, size);
2573 for(k = 0; k < nb_clusters;) {
2575 refcount = get_refcount(bs, k);
2577 while (k < nb_clusters && get_refcount(bs, k) == refcount)
2579 printf("%" PRId64 ": refcount=%d nb=%" PRId64 "\n", k, refcount,
2585 static int qcow2_save_vmstate(BlockDriverState *bs, QEMUIOVector *qiov,
2588 BDRVQcowState *s = bs->opaque;
2589 int64_t total_sectors = bs->total_sectors;
2590 bool zero_beyond_eof = bs->zero_beyond_eof;
2593 BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_SAVE);
2594 bs->zero_beyond_eof = false;
2595 ret = bdrv_pwritev(bs, qcow2_vm_state_offset(s) + pos, qiov);
2596 bs->zero_beyond_eof = zero_beyond_eof;
2598 /* bdrv_co_do_writev will have increased the total_sectors value to include
2599 * the VM state - the VM state is however not an actual part of the block
2600 * device, therefore, we need to restore the old value. */
2601 bs->total_sectors = total_sectors;
2606 static int qcow2_load_vmstate(BlockDriverState *bs, uint8_t *buf,
2607 int64_t pos, int size)
2609 BDRVQcowState *s = bs->opaque;
2610 bool zero_beyond_eof = bs->zero_beyond_eof;
2613 BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_LOAD);
2614 bs->zero_beyond_eof = false;
2615 ret = bdrv_pread(bs, qcow2_vm_state_offset(s) + pos, buf, size);
2616 bs->zero_beyond_eof = zero_beyond_eof;
2622 * Downgrades an image's version. To achieve this, any incompatible features
2623 * have to be removed.
2625 static int qcow2_downgrade(BlockDriverState *bs, int target_version,
2626 BlockDriverAmendStatusCB *status_cb)
2628 BDRVQcowState *s = bs->opaque;
2629 int current_version = s->qcow_version;
2632 if (target_version == current_version) {
2634 } else if (target_version > current_version) {
2636 } else if (target_version != 2) {
2640 if (s->refcount_order != 4) {
2641 /* we would have to convert the image to a refcount_order == 4 image
2642 * here; however, since qemu (at the time of writing this) does not
2643 * support anything different than 4 anyway, there is no point in doing
2644 * so right now; however, we should error out (if qemu supports this in
2645 * the future and this code has not been adapted) */
2646 error_report("qcow2_downgrade: Image refcount orders other than 4 are "
2647 "currently not supported.");
2651 /* clear incompatible features */
2652 if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
2653 ret = qcow2_mark_clean(bs);
2659 /* with QCOW2_INCOMPAT_CORRUPT, it is pretty much impossible to get here in
2660 * the first place; if that happens nonetheless, returning -ENOTSUP is the
2661 * best thing to do anyway */
2663 if (s->incompatible_features) {
2667 /* since we can ignore compatible features, we can set them to 0 as well */
2668 s->compatible_features = 0;
2669 /* if lazy refcounts have been used, they have already been fixed through
2670 * clearing the dirty flag */
2672 /* clearing autoclear features is trivial */
2673 s->autoclear_features = 0;
2675 ret = qcow2_expand_zero_clusters(bs, status_cb);
2680 s->qcow_version = target_version;
2681 ret = qcow2_update_header(bs);
2683 s->qcow_version = current_version;
2689 static int qcow2_amend_options(BlockDriverState *bs, QemuOpts *opts,
2690 BlockDriverAmendStatusCB *status_cb)
2692 BDRVQcowState *s = bs->opaque;
2693 int old_version = s->qcow_version, new_version = old_version;
2694 uint64_t new_size = 0;
2695 const char *backing_file = NULL, *backing_format = NULL;
2696 bool lazy_refcounts = s->use_lazy_refcounts;
2697 const char *compat = NULL;
2698 uint64_t cluster_size = s->cluster_size;
2701 QemuOptDesc *desc = opts->list->desc;
2703 while (desc && desc->name) {
2704 if (!qemu_opt_find(opts, desc->name)) {
2705 /* only change explicitly defined options */
2710 if (!strcmp(desc->name, BLOCK_OPT_COMPAT_LEVEL)) {
2711 compat = qemu_opt_get(opts, BLOCK_OPT_COMPAT_LEVEL);
2713 /* preserve default */
2714 } else if (!strcmp(compat, "0.10")) {
2716 } else if (!strcmp(compat, "1.1")) {
2719 fprintf(stderr, "Unknown compatibility level %s.\n", compat);
2722 } else if (!strcmp(desc->name, BLOCK_OPT_PREALLOC)) {
2723 fprintf(stderr, "Cannot change preallocation mode.\n");
2725 } else if (!strcmp(desc->name, BLOCK_OPT_SIZE)) {
2726 new_size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, 0);
2727 } else if (!strcmp(desc->name, BLOCK_OPT_BACKING_FILE)) {
2728 backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE);
2729 } else if (!strcmp(desc->name, BLOCK_OPT_BACKING_FMT)) {
2730 backing_format = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT);
2731 } else if (!strcmp(desc->name, BLOCK_OPT_ENCRYPT)) {
2732 encrypt = qemu_opt_get_bool(opts, BLOCK_OPT_ENCRYPT,
2735 if (encrypt != !!s->cipher) {
2736 fprintf(stderr, "Changing the encryption flag is not "
2740 } else if (!strcmp(desc->name, BLOCK_OPT_CLUSTER_SIZE)) {
2741 cluster_size = qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE,
2743 if (cluster_size != s->cluster_size) {
2744 fprintf(stderr, "Changing the cluster size is not "
2748 } else if (!strcmp(desc->name, BLOCK_OPT_LAZY_REFCOUNTS)) {
2749 lazy_refcounts = qemu_opt_get_bool(opts, BLOCK_OPT_LAZY_REFCOUNTS,
2751 } else if (!strcmp(desc->name, BLOCK_OPT_REFCOUNT_BITS)) {
2752 error_report("Cannot change refcount entry width");
2755 /* if this assertion fails, this probably means a new option was
2756 * added without having it covered here */
2763 if (new_version != old_version) {
2764 if (new_version > old_version) {
2766 s->qcow_version = new_version;
2767 ret = qcow2_update_header(bs);
2769 s->qcow_version = old_version;
2773 ret = qcow2_downgrade(bs, new_version, status_cb);
2780 if (backing_file || backing_format) {
2781 ret = qcow2_change_backing_file(bs,
2782 backing_file ?: s->image_backing_file,
2783 backing_format ?: s->image_backing_format);
2789 if (s->use_lazy_refcounts != lazy_refcounts) {
2790 if (lazy_refcounts) {
2791 if (s->qcow_version < 3) {
2792 fprintf(stderr, "Lazy refcounts only supported with compatibility "
2793 "level 1.1 and above (use compat=1.1 or greater)\n");
2796 s->compatible_features |= QCOW2_COMPAT_LAZY_REFCOUNTS;
2797 ret = qcow2_update_header(bs);
2799 s->compatible_features &= ~QCOW2_COMPAT_LAZY_REFCOUNTS;
2802 s->use_lazy_refcounts = true;
2804 /* make image clean first */
2805 ret = qcow2_mark_clean(bs);
2809 /* now disallow lazy refcounts */
2810 s->compatible_features &= ~QCOW2_COMPAT_LAZY_REFCOUNTS;
2811 ret = qcow2_update_header(bs);
2813 s->compatible_features |= QCOW2_COMPAT_LAZY_REFCOUNTS;
2816 s->use_lazy_refcounts = false;
2821 ret = bdrv_truncate(bs, new_size);
2831 * If offset or size are negative, respectively, they will not be included in
2832 * the BLOCK_IMAGE_CORRUPTED event emitted.
2833 * fatal will be ignored for read-only BDS; corruptions found there will always
2834 * be considered non-fatal.
2836 void qcow2_signal_corruption(BlockDriverState *bs, bool fatal, int64_t offset,
2837 int64_t size, const char *message_format, ...)
2839 BDRVQcowState *s = bs->opaque;
2840 const char *node_name;
2844 fatal = fatal && !bs->read_only;
2846 if (s->signaled_corruption &&
2847 (!fatal || (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT)))
2852 va_start(ap, message_format);
2853 message = g_strdup_vprintf(message_format, ap);
2857 fprintf(stderr, "qcow2: Marking image as corrupt: %s; further "
2858 "corruption events will be suppressed\n", message);
2860 fprintf(stderr, "qcow2: Image is corrupt: %s; further non-fatal "
2861 "corruption events will be suppressed\n", message);
2864 node_name = bdrv_get_node_name(bs);
2865 qapi_event_send_block_image_corrupted(bdrv_get_device_name(bs),
2866 *node_name != '\0', node_name,
2867 message, offset >= 0, offset,
2869 fatal, &error_abort);
2873 qcow2_mark_corrupt(bs);
2874 bs->drv = NULL; /* make BDS unusable */
2877 s->signaled_corruption = true;
2880 static QemuOptsList qcow2_create_opts = {
2881 .name = "qcow2-create-opts",
2882 .head = QTAILQ_HEAD_INITIALIZER(qcow2_create_opts.head),
2885 .name = BLOCK_OPT_SIZE,
2886 .type = QEMU_OPT_SIZE,
2887 .help = "Virtual disk size"
2890 .name = BLOCK_OPT_COMPAT_LEVEL,
2891 .type = QEMU_OPT_STRING,
2892 .help = "Compatibility level (0.10 or 1.1)"
2895 .name = BLOCK_OPT_BACKING_FILE,
2896 .type = QEMU_OPT_STRING,
2897 .help = "File name of a base image"
2900 .name = BLOCK_OPT_BACKING_FMT,
2901 .type = QEMU_OPT_STRING,
2902 .help = "Image format of the base image"
2905 .name = BLOCK_OPT_ENCRYPT,
2906 .type = QEMU_OPT_BOOL,
2907 .help = "Encrypt the image",
2908 .def_value_str = "off"
2911 .name = BLOCK_OPT_CLUSTER_SIZE,
2912 .type = QEMU_OPT_SIZE,
2913 .help = "qcow2 cluster size",
2914 .def_value_str = stringify(DEFAULT_CLUSTER_SIZE)
2917 .name = BLOCK_OPT_PREALLOC,
2918 .type = QEMU_OPT_STRING,
2919 .help = "Preallocation mode (allowed values: off, metadata, "
2923 .name = BLOCK_OPT_LAZY_REFCOUNTS,
2924 .type = QEMU_OPT_BOOL,
2925 .help = "Postpone refcount updates",
2926 .def_value_str = "off"
2929 .name = BLOCK_OPT_REFCOUNT_BITS,
2930 .type = QEMU_OPT_NUMBER,
2931 .help = "Width of a reference count entry in bits",
2932 .def_value_str = "16"
2934 { /* end of list */ }
2938 BlockDriver bdrv_qcow2 = {
2939 .format_name = "qcow2",
2940 .instance_size = sizeof(BDRVQcowState),
2941 .bdrv_probe = qcow2_probe,
2942 .bdrv_open = qcow2_open,
2943 .bdrv_close = qcow2_close,
2944 .bdrv_reopen_prepare = qcow2_reopen_prepare,
2945 .bdrv_create = qcow2_create,
2946 .bdrv_has_zero_init = bdrv_has_zero_init_1,
2947 .bdrv_co_get_block_status = qcow2_co_get_block_status,
2948 .bdrv_set_key = qcow2_set_key,
2950 .bdrv_co_readv = qcow2_co_readv,
2951 .bdrv_co_writev = qcow2_co_writev,
2952 .bdrv_co_flush_to_os = qcow2_co_flush_to_os,
2954 .bdrv_co_write_zeroes = qcow2_co_write_zeroes,
2955 .bdrv_co_discard = qcow2_co_discard,
2956 .bdrv_truncate = qcow2_truncate,
2957 .bdrv_write_compressed = qcow2_write_compressed,
2958 .bdrv_make_empty = qcow2_make_empty,
2960 .bdrv_snapshot_create = qcow2_snapshot_create,
2961 .bdrv_snapshot_goto = qcow2_snapshot_goto,
2962 .bdrv_snapshot_delete = qcow2_snapshot_delete,
2963 .bdrv_snapshot_list = qcow2_snapshot_list,
2964 .bdrv_snapshot_load_tmp = qcow2_snapshot_load_tmp,
2965 .bdrv_get_info = qcow2_get_info,
2966 .bdrv_get_specific_info = qcow2_get_specific_info,
2968 .bdrv_save_vmstate = qcow2_save_vmstate,
2969 .bdrv_load_vmstate = qcow2_load_vmstate,
2971 .supports_backing = true,
2972 .bdrv_change_backing_file = qcow2_change_backing_file,
2974 .bdrv_refresh_limits = qcow2_refresh_limits,
2975 .bdrv_invalidate_cache = qcow2_invalidate_cache,
2977 .create_opts = &qcow2_create_opts,
2978 .bdrv_check = qcow2_check,
2979 .bdrv_amend_options = qcow2_amend_options,
2982 static void bdrv_qcow2_init(void)
2984 bdrv_register(&bdrv_qcow2);
2987 block_init(bdrv_qcow2_init);