2 * Block driver for the QCOW 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/osdep.h"
25 #include "qapi/error.h"
26 #include "qemu-common.h"
27 #include "qemu/error-report.h"
28 #include "block/block_int.h"
29 #include "sysemu/block-backend.h"
30 #include "qemu/module.h"
31 #include "qemu/bswap.h"
33 #include "qapi/qmp/qerror.h"
34 #include "crypto/cipher.h"
35 #include "migration/migration.h"
37 /**************************************************************/
38 /* QEMU COW block driver with compression and encryption support */
40 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
41 #define QCOW_VERSION 1
43 #define QCOW_CRYPT_NONE 0
44 #define QCOW_CRYPT_AES 1
46 #define QCOW_OFLAG_COMPRESSED (1LL << 63)
48 typedef struct QCowHeader
{
51 uint64_t backing_file_offset
;
52 uint32_t backing_file_size
;
54 uint64_t size
; /* in bytes */
58 uint32_t crypt_method
;
59 uint64_t l1_table_offset
;
60 } QEMU_PACKED QCowHeader
;
62 #define L2_CACHE_SIZE 16
64 typedef struct BDRVQcowState
{
71 uint64_t cluster_offset_mask
;
72 uint64_t l1_table_offset
;
75 uint64_t l2_cache_offsets
[L2_CACHE_SIZE
];
76 uint32_t l2_cache_counts
[L2_CACHE_SIZE
];
77 uint8_t *cluster_cache
;
78 uint8_t *cluster_data
;
79 uint64_t cluster_cache_offset
;
80 QCryptoCipher
*cipher
; /* NULL if no key yet */
81 uint32_t crypt_method_header
;
83 Error
*migration_blocker
;
86 static int decompress_cluster(BlockDriverState
*bs
, uint64_t cluster_offset
);
88 static int qcow_probe(const uint8_t *buf
, int buf_size
, const char *filename
)
90 const QCowHeader
*cow_header
= (const void *)buf
;
92 if (buf_size
>= sizeof(QCowHeader
) &&
93 be32_to_cpu(cow_header
->magic
) == QCOW_MAGIC
&&
94 be32_to_cpu(cow_header
->version
) == QCOW_VERSION
)
100 static int qcow_open(BlockDriverState
*bs
, QDict
*options
, int flags
,
103 BDRVQcowState
*s
= bs
->opaque
;
104 unsigned int len
, i
, shift
;
108 ret
= bdrv_pread(bs
->file
, 0, &header
, sizeof(header
));
112 be32_to_cpus(&header
.magic
);
113 be32_to_cpus(&header
.version
);
114 be64_to_cpus(&header
.backing_file_offset
);
115 be32_to_cpus(&header
.backing_file_size
);
116 be32_to_cpus(&header
.mtime
);
117 be64_to_cpus(&header
.size
);
118 be32_to_cpus(&header
.crypt_method
);
119 be64_to_cpus(&header
.l1_table_offset
);
121 if (header
.magic
!= QCOW_MAGIC
) {
122 error_setg(errp
, "Image not in qcow format");
126 if (header
.version
!= QCOW_VERSION
) {
127 error_setg(errp
, "Unsupported qcow version %" PRIu32
, header
.version
);
132 if (header
.size
<= 1) {
133 error_setg(errp
, "Image size is too small (must be at least 2 bytes)");
137 if (header
.cluster_bits
< 9 || header
.cluster_bits
> 16) {
138 error_setg(errp
, "Cluster size must be between 512 and 64k");
143 /* l2_bits specifies number of entries; storing a uint64_t in each entry,
144 * so bytes = num_entries << 3. */
145 if (header
.l2_bits
< 9 - 3 || header
.l2_bits
> 16 - 3) {
146 error_setg(errp
, "L2 table size must be between 512 and 64k");
151 if (header
.crypt_method
> QCOW_CRYPT_AES
) {
152 error_setg(errp
, "invalid encryption method in qcow header");
156 if (!qcrypto_cipher_supports(QCRYPTO_CIPHER_ALG_AES_128
)) {
157 error_setg(errp
, "AES cipher not available");
161 s
->crypt_method_header
= header
.crypt_method
;
162 if (s
->crypt_method_header
) {
163 if (bdrv_uses_whitelist() &&
164 s
->crypt_method_header
== QCOW_CRYPT_AES
) {
166 "Use of AES-CBC encrypted qcow images is no longer "
167 "supported in system emulators");
168 error_append_hint(errp
,
169 "You can use 'qemu-img convert' to convert your "
170 "image to an alternative supported format, such "
171 "as unencrypted qcow, or raw with the LUKS "
172 "format instead.\n");
177 bs
->encrypted
= true;
179 s
->cluster_bits
= header
.cluster_bits
;
180 s
->cluster_size
= 1 << s
->cluster_bits
;
181 s
->cluster_sectors
= 1 << (s
->cluster_bits
- 9);
182 s
->l2_bits
= header
.l2_bits
;
183 s
->l2_size
= 1 << s
->l2_bits
;
184 bs
->total_sectors
= header
.size
/ 512;
185 s
->cluster_offset_mask
= (1LL << (63 - s
->cluster_bits
)) - 1;
187 /* read the level 1 table */
188 shift
= s
->cluster_bits
+ s
->l2_bits
;
189 if (header
.size
> UINT64_MAX
- (1LL << shift
)) {
190 error_setg(errp
, "Image too large");
194 uint64_t l1_size
= (header
.size
+ (1LL << shift
) - 1) >> shift
;
195 if (l1_size
> INT_MAX
/ sizeof(uint64_t)) {
196 error_setg(errp
, "Image too large");
200 s
->l1_size
= l1_size
;
203 s
->l1_table_offset
= header
.l1_table_offset
;
204 s
->l1_table
= g_try_new(uint64_t, s
->l1_size
);
205 if (s
->l1_table
== NULL
) {
206 error_setg(errp
, "Could not allocate memory for L1 table");
211 ret
= bdrv_pread(bs
->file
, s
->l1_table_offset
, s
->l1_table
,
212 s
->l1_size
* sizeof(uint64_t));
217 for(i
= 0;i
< s
->l1_size
; i
++) {
218 be64_to_cpus(&s
->l1_table
[i
]);
221 /* alloc L2 cache (max. 64k * 16 * 8 = 8 MB) */
223 qemu_try_blockalign(bs
->file
->bs
,
224 s
->l2_size
* L2_CACHE_SIZE
* sizeof(uint64_t));
225 if (s
->l2_cache
== NULL
) {
226 error_setg(errp
, "Could not allocate L2 table cache");
230 s
->cluster_cache
= g_malloc(s
->cluster_size
);
231 s
->cluster_data
= g_malloc(s
->cluster_size
);
232 s
->cluster_cache_offset
= -1;
234 /* read the backing file name */
235 if (header
.backing_file_offset
!= 0) {
236 len
= header
.backing_file_size
;
237 if (len
> 1023 || len
>= sizeof(bs
->backing_file
)) {
238 error_setg(errp
, "Backing file name too long");
242 ret
= bdrv_pread(bs
->file
, header
.backing_file_offset
,
243 bs
->backing_file
, len
);
247 bs
->backing_file
[len
] = '\0';
250 /* Disable migration when qcow images are used */
251 error_setg(&s
->migration_blocker
, "The qcow format used by node '%s' "
252 "does not support live migration",
253 bdrv_get_device_or_node_name(bs
));
254 migrate_add_blocker(s
->migration_blocker
);
256 qemu_co_mutex_init(&s
->lock
);
261 qemu_vfree(s
->l2_cache
);
262 g_free(s
->cluster_cache
);
263 g_free(s
->cluster_data
);
268 /* We have nothing to do for QCOW reopen, stubs just return
270 static int qcow_reopen_prepare(BDRVReopenState
*state
,
271 BlockReopenQueue
*queue
, Error
**errp
)
276 static int qcow_set_key(BlockDriverState
*bs
, const char *key
)
278 BDRVQcowState
*s
= bs
->opaque
;
283 memset(keybuf
, 0, 16);
287 /* XXX: we could compress the chars to 7 bits to increase
289 for(i
= 0;i
< len
;i
++) {
292 assert(bs
->encrypted
);
294 qcrypto_cipher_free(s
->cipher
);
295 s
->cipher
= qcrypto_cipher_new(
296 QCRYPTO_CIPHER_ALG_AES_128
,
297 QCRYPTO_CIPHER_MODE_CBC
,
298 keybuf
, G_N_ELEMENTS(keybuf
),
302 /* XXX would be nice if errors in this method could
303 * be properly propagate to the caller. Would need
304 * the bdrv_set_key() API signature to be fixed. */
311 /* The crypt function is compatible with the linux cryptoloop
312 algorithm for < 4 GB images. NOTE: out_buf == in_buf is
314 static int encrypt_sectors(BDRVQcowState
*s
, int64_t sector_num
,
315 uint8_t *out_buf
, const uint8_t *in_buf
,
316 int nb_sectors
, bool enc
, Error
**errp
)
325 for(i
= 0; i
< nb_sectors
; i
++) {
326 ivec
.ll
[0] = cpu_to_le64(sector_num
);
328 if (qcrypto_cipher_setiv(s
->cipher
,
329 ivec
.b
, G_N_ELEMENTS(ivec
.b
),
334 ret
= qcrypto_cipher_encrypt(s
->cipher
,
340 ret
= qcrypto_cipher_decrypt(s
->cipher
,
360 * 1 to allocate a normal cluster (for sector indexes 'n_start' to
363 * 2 to allocate a compressed cluster of size
364 * 'compressed_size'. 'compressed_size' must be > 0 and <
367 * return 0 if not allocated.
369 static uint64_t get_cluster_offset(BlockDriverState
*bs
,
370 uint64_t offset
, int allocate
,
372 int n_start
, int n_end
)
374 BDRVQcowState
*s
= bs
->opaque
;
375 int min_index
, i
, j
, l1_index
, l2_index
;
376 uint64_t l2_offset
, *l2_table
, cluster_offset
, tmp
;
380 l1_index
= offset
>> (s
->l2_bits
+ s
->cluster_bits
);
381 l2_offset
= s
->l1_table
[l1_index
];
386 /* allocate a new l2 entry */
387 l2_offset
= bdrv_getlength(bs
->file
->bs
);
388 /* round to cluster size */
389 l2_offset
= (l2_offset
+ s
->cluster_size
- 1) & ~(s
->cluster_size
- 1);
390 /* update the L1 entry */
391 s
->l1_table
[l1_index
] = l2_offset
;
392 tmp
= cpu_to_be64(l2_offset
);
393 if (bdrv_pwrite_sync(bs
->file
,
394 s
->l1_table_offset
+ l1_index
* sizeof(tmp
),
395 &tmp
, sizeof(tmp
)) < 0)
399 for(i
= 0; i
< L2_CACHE_SIZE
; i
++) {
400 if (l2_offset
== s
->l2_cache_offsets
[i
]) {
401 /* increment the hit count */
402 if (++s
->l2_cache_counts
[i
] == 0xffffffff) {
403 for(j
= 0; j
< L2_CACHE_SIZE
; j
++) {
404 s
->l2_cache_counts
[j
] >>= 1;
407 l2_table
= s
->l2_cache
+ (i
<< s
->l2_bits
);
411 /* not found: load a new entry in the least used one */
413 min_count
= 0xffffffff;
414 for(i
= 0; i
< L2_CACHE_SIZE
; i
++) {
415 if (s
->l2_cache_counts
[i
] < min_count
) {
416 min_count
= s
->l2_cache_counts
[i
];
420 l2_table
= s
->l2_cache
+ (min_index
<< s
->l2_bits
);
422 memset(l2_table
, 0, s
->l2_size
* sizeof(uint64_t));
423 if (bdrv_pwrite_sync(bs
->file
, l2_offset
, l2_table
,
424 s
->l2_size
* sizeof(uint64_t)) < 0)
427 if (bdrv_pread(bs
->file
, l2_offset
, l2_table
,
428 s
->l2_size
* sizeof(uint64_t)) !=
429 s
->l2_size
* sizeof(uint64_t))
432 s
->l2_cache_offsets
[min_index
] = l2_offset
;
433 s
->l2_cache_counts
[min_index
] = 1;
435 l2_index
= (offset
>> s
->cluster_bits
) & (s
->l2_size
- 1);
436 cluster_offset
= be64_to_cpu(l2_table
[l2_index
]);
437 if (!cluster_offset
||
438 ((cluster_offset
& QCOW_OFLAG_COMPRESSED
) && allocate
== 1)) {
441 /* allocate a new cluster */
442 if ((cluster_offset
& QCOW_OFLAG_COMPRESSED
) &&
443 (n_end
- n_start
) < s
->cluster_sectors
) {
444 /* if the cluster is already compressed, we must
445 decompress it in the case it is not completely
447 if (decompress_cluster(bs
, cluster_offset
) < 0)
449 cluster_offset
= bdrv_getlength(bs
->file
->bs
);
450 cluster_offset
= (cluster_offset
+ s
->cluster_size
- 1) &
451 ~(s
->cluster_size
- 1);
452 /* write the cluster content */
453 if (bdrv_pwrite(bs
->file
, cluster_offset
, s
->cluster_cache
,
458 cluster_offset
= bdrv_getlength(bs
->file
->bs
);
460 /* round to cluster size */
461 cluster_offset
= (cluster_offset
+ s
->cluster_size
- 1) &
462 ~(s
->cluster_size
- 1);
463 bdrv_truncate(bs
->file
->bs
, cluster_offset
+ s
->cluster_size
);
464 /* if encrypted, we must initialize the cluster
465 content which won't be written */
467 (n_end
- n_start
) < s
->cluster_sectors
) {
470 start_sect
= (offset
& ~(s
->cluster_size
- 1)) >> 9;
471 memset(s
->cluster_data
+ 512, 0x00, 512);
472 for(i
= 0; i
< s
->cluster_sectors
; i
++) {
473 if (i
< n_start
|| i
>= n_end
) {
475 if (encrypt_sectors(s
, start_sect
+ i
,
477 s
->cluster_data
+ 512, 1,
483 if (bdrv_pwrite(bs
->file
,
484 cluster_offset
+ i
* 512,
485 s
->cluster_data
, 512) != 512)
490 } else if (allocate
== 2) {
491 cluster_offset
|= QCOW_OFLAG_COMPRESSED
|
492 (uint64_t)compressed_size
<< (63 - s
->cluster_bits
);
495 /* update L2 table */
496 tmp
= cpu_to_be64(cluster_offset
);
497 l2_table
[l2_index
] = tmp
;
498 if (bdrv_pwrite_sync(bs
->file
, l2_offset
+ l2_index
* sizeof(tmp
),
499 &tmp
, sizeof(tmp
)) < 0)
502 return cluster_offset
;
505 static int64_t coroutine_fn
qcow_co_get_block_status(BlockDriverState
*bs
,
506 int64_t sector_num
, int nb_sectors
, int *pnum
, BlockDriverState
**file
)
508 BDRVQcowState
*s
= bs
->opaque
;
509 int index_in_cluster
, n
;
510 uint64_t cluster_offset
;
512 qemu_co_mutex_lock(&s
->lock
);
513 cluster_offset
= get_cluster_offset(bs
, sector_num
<< 9, 0, 0, 0, 0);
514 qemu_co_mutex_unlock(&s
->lock
);
515 index_in_cluster
= sector_num
& (s
->cluster_sectors
- 1);
516 n
= s
->cluster_sectors
- index_in_cluster
;
520 if (!cluster_offset
) {
523 if ((cluster_offset
& QCOW_OFLAG_COMPRESSED
) || s
->cipher
) {
524 return BDRV_BLOCK_DATA
;
526 cluster_offset
|= (index_in_cluster
<< BDRV_SECTOR_BITS
);
527 *file
= bs
->file
->bs
;
528 return BDRV_BLOCK_DATA
| BDRV_BLOCK_OFFSET_VALID
| cluster_offset
;
531 static int decompress_buffer(uint8_t *out_buf
, int out_buf_size
,
532 const uint8_t *buf
, int buf_size
)
534 z_stream strm1
, *strm
= &strm1
;
537 memset(strm
, 0, sizeof(*strm
));
539 strm
->next_in
= (uint8_t *)buf
;
540 strm
->avail_in
= buf_size
;
541 strm
->next_out
= out_buf
;
542 strm
->avail_out
= out_buf_size
;
544 ret
= inflateInit2(strm
, -12);
547 ret
= inflate(strm
, Z_FINISH
);
548 out_len
= strm
->next_out
- out_buf
;
549 if ((ret
!= Z_STREAM_END
&& ret
!= Z_BUF_ERROR
) ||
550 out_len
!= out_buf_size
) {
558 static int decompress_cluster(BlockDriverState
*bs
, uint64_t cluster_offset
)
560 BDRVQcowState
*s
= bs
->opaque
;
564 coffset
= cluster_offset
& s
->cluster_offset_mask
;
565 if (s
->cluster_cache_offset
!= coffset
) {
566 csize
= cluster_offset
>> (63 - s
->cluster_bits
);
567 csize
&= (s
->cluster_size
- 1);
568 ret
= bdrv_pread(bs
->file
, coffset
, s
->cluster_data
, csize
);
571 if (decompress_buffer(s
->cluster_cache
, s
->cluster_size
,
572 s
->cluster_data
, csize
) < 0) {
575 s
->cluster_cache_offset
= coffset
;
580 static coroutine_fn
int qcow_co_readv(BlockDriverState
*bs
, int64_t sector_num
,
581 int nb_sectors
, QEMUIOVector
*qiov
)
583 BDRVQcowState
*s
= bs
->opaque
;
584 int index_in_cluster
;
586 uint64_t cluster_offset
;
588 QEMUIOVector hd_qiov
;
593 if (qiov
->niov
> 1) {
594 buf
= orig_buf
= qemu_try_blockalign(bs
, qiov
->size
);
600 buf
= (uint8_t *)qiov
->iov
->iov_base
;
603 qemu_co_mutex_lock(&s
->lock
);
605 while (nb_sectors
!= 0) {
606 /* prepare next request */
607 cluster_offset
= get_cluster_offset(bs
, sector_num
<< 9,
609 index_in_cluster
= sector_num
& (s
->cluster_sectors
- 1);
610 n
= s
->cluster_sectors
- index_in_cluster
;
611 if (n
> nb_sectors
) {
615 if (!cluster_offset
) {
617 /* read from the base image */
618 hd_iov
.iov_base
= (void *)buf
;
619 hd_iov
.iov_len
= n
* 512;
620 qemu_iovec_init_external(&hd_qiov
, &hd_iov
, 1);
621 qemu_co_mutex_unlock(&s
->lock
);
622 ret
= bdrv_co_readv(bs
->backing
, sector_num
, n
, &hd_qiov
);
623 qemu_co_mutex_lock(&s
->lock
);
628 /* Note: in this case, no need to wait */
629 memset(buf
, 0, 512 * n
);
631 } else if (cluster_offset
& QCOW_OFLAG_COMPRESSED
) {
632 /* add AIO support for compressed blocks ? */
633 if (decompress_cluster(bs
, cluster_offset
) < 0) {
637 s
->cluster_cache
+ index_in_cluster
* 512, 512 * n
);
639 if ((cluster_offset
& 511) != 0) {
642 hd_iov
.iov_base
= (void *)buf
;
643 hd_iov
.iov_len
= n
* 512;
644 qemu_iovec_init_external(&hd_qiov
, &hd_iov
, 1);
645 qemu_co_mutex_unlock(&s
->lock
);
646 ret
= bdrv_co_readv(bs
->file
,
647 (cluster_offset
>> 9) + index_in_cluster
,
649 qemu_co_mutex_lock(&s
->lock
);
655 if (encrypt_sectors(s
, sector_num
, buf
, buf
,
656 n
, false, &err
) < 0) {
669 qemu_co_mutex_unlock(&s
->lock
);
671 if (qiov
->niov
> 1) {
672 qemu_iovec_from_buf(qiov
, 0, orig_buf
, qiov
->size
);
673 qemu_vfree(orig_buf
);
684 static coroutine_fn
int qcow_co_writev(BlockDriverState
*bs
, int64_t sector_num
,
685 int nb_sectors
, QEMUIOVector
*qiov
)
687 BDRVQcowState
*s
= bs
->opaque
;
688 int index_in_cluster
;
689 uint64_t cluster_offset
;
690 const uint8_t *src_buf
;
692 uint8_t *cluster_data
= NULL
;
694 QEMUIOVector hd_qiov
;
698 s
->cluster_cache_offset
= -1; /* disable compressed cache */
700 if (qiov
->niov
> 1) {
701 buf
= orig_buf
= qemu_try_blockalign(bs
, qiov
->size
);
705 qemu_iovec_to_buf(qiov
, 0, buf
, qiov
->size
);
708 buf
= (uint8_t *)qiov
->iov
->iov_base
;
711 qemu_co_mutex_lock(&s
->lock
);
713 while (nb_sectors
!= 0) {
715 index_in_cluster
= sector_num
& (s
->cluster_sectors
- 1);
716 n
= s
->cluster_sectors
- index_in_cluster
;
717 if (n
> nb_sectors
) {
720 cluster_offset
= get_cluster_offset(bs
, sector_num
<< 9, 1, 0,
722 index_in_cluster
+ n
);
723 if (!cluster_offset
|| (cluster_offset
& 511) != 0) {
731 cluster_data
= g_malloc0(s
->cluster_size
);
733 if (encrypt_sectors(s
, sector_num
, cluster_data
, buf
,
734 n
, true, &err
) < 0) {
739 src_buf
= cluster_data
;
744 hd_iov
.iov_base
= (void *)src_buf
;
745 hd_iov
.iov_len
= n
* 512;
746 qemu_iovec_init_external(&hd_qiov
, &hd_iov
, 1);
747 qemu_co_mutex_unlock(&s
->lock
);
748 ret
= bdrv_co_writev(bs
->file
,
749 (cluster_offset
>> 9) + index_in_cluster
,
751 qemu_co_mutex_lock(&s
->lock
);
761 qemu_co_mutex_unlock(&s
->lock
);
763 if (qiov
->niov
> 1) {
764 qemu_vfree(orig_buf
);
766 g_free(cluster_data
);
771 static void qcow_close(BlockDriverState
*bs
)
773 BDRVQcowState
*s
= bs
->opaque
;
775 qcrypto_cipher_free(s
->cipher
);
778 qemu_vfree(s
->l2_cache
);
779 g_free(s
->cluster_cache
);
780 g_free(s
->cluster_data
);
782 migrate_del_blocker(s
->migration_blocker
);
783 error_free(s
->migration_blocker
);
786 static int qcow_create(const char *filename
, QemuOpts
*opts
, Error
**errp
)
788 int header_size
, backing_filename_len
, l1_size
, shift
, i
;
791 int64_t total_size
= 0;
792 char *backing_file
= NULL
;
794 Error
*local_err
= NULL
;
796 BlockBackend
*qcow_blk
;
798 /* Read out options */
799 total_size
= ROUND_UP(qemu_opt_get_size_del(opts
, BLOCK_OPT_SIZE
, 0),
801 backing_file
= qemu_opt_get_del(opts
, BLOCK_OPT_BACKING_FILE
);
802 if (qemu_opt_get_bool_del(opts
, BLOCK_OPT_ENCRYPT
, false)) {
803 flags
|= BLOCK_FLAG_ENCRYPT
;
806 ret
= bdrv_create_file(filename
, opts
, &local_err
);
808 error_propagate(errp
, local_err
);
812 qcow_blk
= blk_new_open(filename
, NULL
, NULL
,
813 BDRV_O_RDWR
| BDRV_O_PROTOCOL
, &local_err
);
814 if (qcow_blk
== NULL
) {
815 error_propagate(errp
, local_err
);
820 blk_set_allow_write_beyond_eof(qcow_blk
, true);
822 ret
= blk_truncate(qcow_blk
, 0);
827 memset(&header
, 0, sizeof(header
));
828 header
.magic
= cpu_to_be32(QCOW_MAGIC
);
829 header
.version
= cpu_to_be32(QCOW_VERSION
);
830 header
.size
= cpu_to_be64(total_size
);
831 header_size
= sizeof(header
);
832 backing_filename_len
= 0;
834 if (strcmp(backing_file
, "fat:")) {
835 header
.backing_file_offset
= cpu_to_be64(header_size
);
836 backing_filename_len
= strlen(backing_file
);
837 header
.backing_file_size
= cpu_to_be32(backing_filename_len
);
838 header_size
+= backing_filename_len
;
840 /* special backing file for vvfat */
843 header
.cluster_bits
= 9; /* 512 byte cluster to avoid copying
844 unmodified sectors */
845 header
.l2_bits
= 12; /* 32 KB L2 tables */
847 header
.cluster_bits
= 12; /* 4 KB clusters */
848 header
.l2_bits
= 9; /* 4 KB L2 tables */
850 header_size
= (header_size
+ 7) & ~7;
851 shift
= header
.cluster_bits
+ header
.l2_bits
;
852 l1_size
= (total_size
+ (1LL << shift
) - 1) >> shift
;
854 header
.l1_table_offset
= cpu_to_be64(header_size
);
855 if (flags
& BLOCK_FLAG_ENCRYPT
) {
856 header
.crypt_method
= cpu_to_be32(QCOW_CRYPT_AES
);
858 header
.crypt_method
= cpu_to_be32(QCOW_CRYPT_NONE
);
861 /* write all the data */
862 ret
= blk_pwrite(qcow_blk
, 0, &header
, sizeof(header
), 0);
863 if (ret
!= sizeof(header
)) {
868 ret
= blk_pwrite(qcow_blk
, sizeof(header
),
869 backing_file
, backing_filename_len
, 0);
870 if (ret
!= backing_filename_len
) {
875 tmp
= g_malloc0(BDRV_SECTOR_SIZE
);
876 for (i
= 0; i
< DIV_ROUND_UP(sizeof(uint64_t) * l1_size
, BDRV_SECTOR_SIZE
);
878 ret
= blk_pwrite(qcow_blk
, header_size
+ BDRV_SECTOR_SIZE
* i
,
879 tmp
, BDRV_SECTOR_SIZE
, 0);
880 if (ret
!= BDRV_SECTOR_SIZE
) {
891 g_free(backing_file
);
895 static int qcow_make_empty(BlockDriverState
*bs
)
897 BDRVQcowState
*s
= bs
->opaque
;
898 uint32_t l1_length
= s
->l1_size
* sizeof(uint64_t);
901 memset(s
->l1_table
, 0, l1_length
);
902 if (bdrv_pwrite_sync(bs
->file
, s
->l1_table_offset
, s
->l1_table
,
905 ret
= bdrv_truncate(bs
->file
->bs
, s
->l1_table_offset
+ l1_length
);
909 memset(s
->l2_cache
, 0, s
->l2_size
* L2_CACHE_SIZE
* sizeof(uint64_t));
910 memset(s
->l2_cache_offsets
, 0, L2_CACHE_SIZE
* sizeof(uint64_t));
911 memset(s
->l2_cache_counts
, 0, L2_CACHE_SIZE
* sizeof(uint32_t));
916 typedef struct QcowWriteCo
{
917 BlockDriverState
*bs
;
924 static void qcow_write_co_entry(void *opaque
)
926 QcowWriteCo
*co
= opaque
;
929 struct iovec iov
= (struct iovec
) {
930 .iov_base
= (uint8_t*) co
->buf
,
931 .iov_len
= co
->nb_sectors
* BDRV_SECTOR_SIZE
,
933 qemu_iovec_init_external(&qiov
, &iov
, 1);
935 co
->ret
= qcow_co_writev(co
->bs
, co
->sector_num
, co
->nb_sectors
, &qiov
);
938 /* Wrapper for non-coroutine contexts */
939 static int qcow_write(BlockDriverState
*bs
, int64_t sector_num
,
940 const uint8_t *buf
, int nb_sectors
)
943 AioContext
*aio_context
= bdrv_get_aio_context(bs
);
946 .sector_num
= sector_num
,
948 .nb_sectors
= nb_sectors
,
951 co
= qemu_coroutine_create(qcow_write_co_entry
, &data
);
952 qemu_coroutine_enter(co
);
953 while (data
.ret
== -EINPROGRESS
) {
954 aio_poll(aio_context
, true);
959 /* XXX: put compressed sectors first, then all the cluster aligned
960 tables to avoid losing bytes in alignment */
961 static int qcow_write_compressed(BlockDriverState
*bs
, int64_t sector_num
,
962 const uint8_t *buf
, int nb_sectors
)
964 BDRVQcowState
*s
= bs
->opaque
;
968 uint64_t cluster_offset
;
970 if (nb_sectors
!= s
->cluster_sectors
) {
973 /* Zero-pad last write if image size is not cluster aligned */
974 if (sector_num
+ nb_sectors
== bs
->total_sectors
&&
975 nb_sectors
< s
->cluster_sectors
) {
976 uint8_t *pad_buf
= qemu_blockalign(bs
, s
->cluster_size
);
977 memset(pad_buf
, 0, s
->cluster_size
);
978 memcpy(pad_buf
, buf
, nb_sectors
* BDRV_SECTOR_SIZE
);
979 ret
= qcow_write_compressed(bs
, sector_num
,
980 pad_buf
, s
->cluster_sectors
);
986 out_buf
= g_malloc(s
->cluster_size
);
988 /* best compression, small window, no zlib header */
989 memset(&strm
, 0, sizeof(strm
));
990 ret
= deflateInit2(&strm
, Z_DEFAULT_COMPRESSION
,
992 9, Z_DEFAULT_STRATEGY
);
998 strm
.avail_in
= s
->cluster_size
;
999 strm
.next_in
= (uint8_t *)buf
;
1000 strm
.avail_out
= s
->cluster_size
;
1001 strm
.next_out
= out_buf
;
1003 ret
= deflate(&strm
, Z_FINISH
);
1004 if (ret
!= Z_STREAM_END
&& ret
!= Z_OK
) {
1009 out_len
= strm
.next_out
- out_buf
;
1013 if (ret
!= Z_STREAM_END
|| out_len
>= s
->cluster_size
) {
1014 /* could not compress: write normal cluster */
1015 ret
= qcow_write(bs
, sector_num
, buf
, s
->cluster_sectors
);
1020 cluster_offset
= get_cluster_offset(bs
, sector_num
<< 9, 2,
1022 if (cluster_offset
== 0) {
1027 cluster_offset
&= s
->cluster_offset_mask
;
1028 ret
= bdrv_pwrite(bs
->file
, cluster_offset
, out_buf
, out_len
);
1040 static int qcow_get_info(BlockDriverState
*bs
, BlockDriverInfo
*bdi
)
1042 BDRVQcowState
*s
= bs
->opaque
;
1043 bdi
->cluster_size
= s
->cluster_size
;
1047 static QemuOptsList qcow_create_opts
= {
1048 .name
= "qcow-create-opts",
1049 .head
= QTAILQ_HEAD_INITIALIZER(qcow_create_opts
.head
),
1052 .name
= BLOCK_OPT_SIZE
,
1053 .type
= QEMU_OPT_SIZE
,
1054 .help
= "Virtual disk size"
1057 .name
= BLOCK_OPT_BACKING_FILE
,
1058 .type
= QEMU_OPT_STRING
,
1059 .help
= "File name of a base image"
1062 .name
= BLOCK_OPT_ENCRYPT
,
1063 .type
= QEMU_OPT_BOOL
,
1064 .help
= "Encrypt the image",
1065 .def_value_str
= "off"
1067 { /* end of list */ }
1071 static BlockDriver bdrv_qcow
= {
1072 .format_name
= "qcow",
1073 .instance_size
= sizeof(BDRVQcowState
),
1074 .bdrv_probe
= qcow_probe
,
1075 .bdrv_open
= qcow_open
,
1076 .bdrv_close
= qcow_close
,
1077 .bdrv_reopen_prepare
= qcow_reopen_prepare
,
1078 .bdrv_create
= qcow_create
,
1079 .bdrv_has_zero_init
= bdrv_has_zero_init_1
,
1080 .supports_backing
= true,
1082 .bdrv_co_readv
= qcow_co_readv
,
1083 .bdrv_co_writev
= qcow_co_writev
,
1084 .bdrv_co_get_block_status
= qcow_co_get_block_status
,
1086 .bdrv_set_key
= qcow_set_key
,
1087 .bdrv_make_empty
= qcow_make_empty
,
1088 .bdrv_write_compressed
= qcow_write_compressed
,
1089 .bdrv_get_info
= qcow_get_info
,
1091 .create_opts
= &qcow_create_opts
,
1094 static void bdrv_qcow_init(void)
1096 bdrv_register(&bdrv_qcow
);
1099 block_init(bdrv_qcow_init
);