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_int.h"
29 #include "block/qcow2.h"
32 Differences with QCOW:
34 - Support for multiple incremental snapshots.
35 - Memory management by reference counts.
36 - Clusters which have a reference count of one have the bit
37 QCOW_OFLAG_COPIED to optimize write performance.
38 - Size of compressed clusters is stored in sectors to reduce bit usage
39 in the cluster offsets.
40 - Support for storing additional data (such as the VM state) in the
42 - If a backing store is used, the cluster size is not constrained
43 (could be backported to QCOW).
44 - L2 tables have always a size of one cluster.
52 #define QCOW_EXT_MAGIC_END 0
53 #define QCOW_EXT_MAGIC_BACKING_FORMAT 0xE2792ACA
57 static int qcow_probe(const uint8_t *buf
, int buf_size
, const char *filename
)
59 const QCowHeader
*cow_header
= (const void *)buf
;
61 if (buf_size
>= sizeof(QCowHeader
) &&
62 be32_to_cpu(cow_header
->magic
) == QCOW_MAGIC
&&
63 be32_to_cpu(cow_header
->version
) == QCOW_VERSION
)
71 * read qcow2 extension and fill bs
72 * start reading from start_offset
73 * finish reading upon magic of value 0 or when end_offset reached
74 * unknown magic is skipped (future extension this version knows nothing about)
75 * return 0 upon success, non-0 otherwise
77 static int qcow_read_extensions(BlockDriverState
*bs
, uint64_t start_offset
,
80 BDRVQcowState
*s
= bs
->opaque
;
85 printf("qcow_read_extensions: start=%ld end=%ld\n", start_offset
, end_offset
);
87 offset
= start_offset
;
88 while (offset
< end_offset
) {
92 if (offset
> s
->cluster_size
)
93 printf("qcow_handle_extension: suspicious offset %lu\n", offset
);
95 printf("attemting to read extended header in offset %lu\n", offset
);
98 if (bdrv_pread(s
->hd
, offset
, &ext
, sizeof(ext
)) != sizeof(ext
)) {
99 fprintf(stderr
, "qcow_handle_extension: ERROR: pread fail from offset %llu\n",
100 (unsigned long long)offset
);
103 be32_to_cpus(&ext
.magic
);
104 be32_to_cpus(&ext
.len
);
105 offset
+= sizeof(ext
);
107 printf("ext.magic = 0x%x\n", ext
.magic
);
110 case QCOW_EXT_MAGIC_END
:
113 case QCOW_EXT_MAGIC_BACKING_FORMAT
:
114 if (ext
.len
>= sizeof(bs
->backing_format
)) {
115 fprintf(stderr
, "ERROR: ext_backing_format: len=%u too large"
117 ext
.len
, sizeof(bs
->backing_format
));
120 if (bdrv_pread(s
->hd
, offset
, bs
->backing_format
,
123 bs
->backing_format
[ext
.len
] = '\0';
125 printf("Qcow2: Got format extension %s\n", bs
->backing_format
);
127 offset
= ((offset
+ ext
.len
+ 7) & ~7);
131 /* unknown magic -- just skip it */
132 offset
= ((offset
+ ext
.len
+ 7) & ~7);
141 static int qcow_open(BlockDriverState
*bs
, const char *filename
, int flags
)
143 BDRVQcowState
*s
= bs
->opaque
;
144 int len
, i
, shift
, ret
;
148 ret
= bdrv_file_open(&s
->hd
, filename
, flags
);
151 if (bdrv_pread(s
->hd
, 0, &header
, sizeof(header
)) != sizeof(header
))
153 be32_to_cpus(&header
.magic
);
154 be32_to_cpus(&header
.version
);
155 be64_to_cpus(&header
.backing_file_offset
);
156 be32_to_cpus(&header
.backing_file_size
);
157 be64_to_cpus(&header
.size
);
158 be32_to_cpus(&header
.cluster_bits
);
159 be32_to_cpus(&header
.crypt_method
);
160 be64_to_cpus(&header
.l1_table_offset
);
161 be32_to_cpus(&header
.l1_size
);
162 be64_to_cpus(&header
.refcount_table_offset
);
163 be32_to_cpus(&header
.refcount_table_clusters
);
164 be64_to_cpus(&header
.snapshots_offset
);
165 be32_to_cpus(&header
.nb_snapshots
);
167 if (header
.magic
!= QCOW_MAGIC
|| header
.version
!= QCOW_VERSION
)
169 if (header
.cluster_bits
< MIN_CLUSTER_BITS
||
170 header
.cluster_bits
> MAX_CLUSTER_BITS
)
172 if (header
.crypt_method
> QCOW_CRYPT_AES
)
174 s
->crypt_method_header
= header
.crypt_method
;
175 if (s
->crypt_method_header
)
177 s
->cluster_bits
= header
.cluster_bits
;
178 s
->cluster_size
= 1 << s
->cluster_bits
;
179 s
->cluster_sectors
= 1 << (s
->cluster_bits
- 9);
180 s
->l2_bits
= s
->cluster_bits
- 3; /* L2 is always one cluster */
181 s
->l2_size
= 1 << s
->l2_bits
;
182 bs
->total_sectors
= header
.size
/ 512;
183 s
->csize_shift
= (62 - (s
->cluster_bits
- 8));
184 s
->csize_mask
= (1 << (s
->cluster_bits
- 8)) - 1;
185 s
->cluster_offset_mask
= (1LL << s
->csize_shift
) - 1;
186 s
->refcount_table_offset
= header
.refcount_table_offset
;
187 s
->refcount_table_size
=
188 header
.refcount_table_clusters
<< (s
->cluster_bits
- 3);
190 s
->snapshots_offset
= header
.snapshots_offset
;
191 s
->nb_snapshots
= header
.nb_snapshots
;
193 /* read the level 1 table */
194 s
->l1_size
= header
.l1_size
;
195 shift
= s
->cluster_bits
+ s
->l2_bits
;
196 s
->l1_vm_state_index
= (header
.size
+ (1LL << shift
) - 1) >> shift
;
197 /* the L1 table must contain at least enough entries to put
199 if (s
->l1_size
< s
->l1_vm_state_index
)
201 s
->l1_table_offset
= header
.l1_table_offset
;
202 if (s
->l1_size
> 0) {
203 s
->l1_table
= qemu_mallocz(
204 align_offset(s
->l1_size
* sizeof(uint64_t), 512));
205 if (bdrv_pread(s
->hd
, s
->l1_table_offset
, s
->l1_table
, s
->l1_size
* sizeof(uint64_t)) !=
206 s
->l1_size
* sizeof(uint64_t))
208 for(i
= 0;i
< s
->l1_size
; i
++) {
209 be64_to_cpus(&s
->l1_table
[i
]);
213 s
->l2_cache
= qemu_malloc(s
->l2_size
* L2_CACHE_SIZE
* sizeof(uint64_t));
214 s
->cluster_cache
= qemu_malloc(s
->cluster_size
);
215 /* one more sector for decompressed data alignment */
216 s
->cluster_data
= qemu_malloc(QCOW_MAX_CRYPT_CLUSTERS
* s
->cluster_size
218 s
->cluster_cache_offset
= -1;
220 if (qcow2_refcount_init(bs
) < 0)
223 QLIST_INIT(&s
->cluster_allocs
);
225 /* read qcow2 extensions */
226 if (header
.backing_file_offset
)
227 ext_end
= header
.backing_file_offset
;
229 ext_end
= s
->cluster_size
;
230 if (qcow_read_extensions(bs
, sizeof(header
), ext_end
))
233 /* read the backing file name */
234 if (header
.backing_file_offset
!= 0) {
235 len
= header
.backing_file_size
;
238 if (bdrv_pread(s
->hd
, header
.backing_file_offset
, bs
->backing_file
, len
) != len
)
240 bs
->backing_file
[len
] = '\0';
242 if (qcow2_read_snapshots(bs
) < 0)
246 qcow2_check_refcounts(bs
);
251 qcow2_free_snapshots(bs
);
252 qcow2_refcount_close(bs
);
253 qemu_free(s
->l1_table
);
254 qemu_free(s
->l2_cache
);
255 qemu_free(s
->cluster_cache
);
256 qemu_free(s
->cluster_data
);
261 static int qcow_set_key(BlockDriverState
*bs
, const char *key
)
263 BDRVQcowState
*s
= bs
->opaque
;
267 memset(keybuf
, 0, 16);
271 /* XXX: we could compress the chars to 7 bits to increase
273 for(i
= 0;i
< len
;i
++) {
276 s
->crypt_method
= s
->crypt_method_header
;
278 if (AES_set_encrypt_key(keybuf
, 128, &s
->aes_encrypt_key
) != 0)
280 if (AES_set_decrypt_key(keybuf
, 128, &s
->aes_decrypt_key
) != 0)
290 AES_encrypt(in
, tmp
, &s
->aes_encrypt_key
);
291 AES_decrypt(tmp
, out
, &s
->aes_decrypt_key
);
292 for(i
= 0; i
< 16; i
++)
293 printf(" %02x", tmp
[i
]);
295 for(i
= 0; i
< 16; i
++)
296 printf(" %02x", out
[i
]);
303 static int qcow_is_allocated(BlockDriverState
*bs
, int64_t sector_num
,
304 int nb_sectors
, int *pnum
)
306 uint64_t cluster_offset
;
309 cluster_offset
= qcow2_get_cluster_offset(bs
, sector_num
<< 9, pnum
);
311 return (cluster_offset
!= 0);
314 /* handle reading after the end of the backing file */
315 int qcow2_backing_read1(BlockDriverState
*bs
,
316 int64_t sector_num
, uint8_t *buf
, int nb_sectors
)
319 if ((sector_num
+ nb_sectors
) <= bs
->total_sectors
)
321 if (sector_num
>= bs
->total_sectors
)
324 n1
= bs
->total_sectors
- sector_num
;
325 memset(buf
+ n1
* 512, 0, 512 * (nb_sectors
- n1
));
329 typedef struct QCowAIOCB
{
330 BlockDriverAIOCB common
;
337 uint64_t cluster_offset
;
338 uint8_t *cluster_data
;
339 BlockDriverAIOCB
*hd_aiocb
;
341 QEMUIOVector hd_qiov
;
344 QLIST_ENTRY(QCowAIOCB
) next_depend
;
347 static void qcow_aio_cancel(BlockDriverAIOCB
*blockacb
)
349 QCowAIOCB
*acb
= (QCowAIOCB
*)blockacb
;
351 bdrv_aio_cancel(acb
->hd_aiocb
);
352 qemu_aio_release(acb
);
355 static AIOPool qcow_aio_pool
= {
356 .aiocb_size
= sizeof(QCowAIOCB
),
357 .cancel
= qcow_aio_cancel
,
360 static void qcow_aio_read_cb(void *opaque
, int ret
);
361 static void qcow_aio_read_bh(void *opaque
)
363 QCowAIOCB
*acb
= opaque
;
364 qemu_bh_delete(acb
->bh
);
366 qcow_aio_read_cb(opaque
, 0);
369 static int qcow_schedule_bh(QEMUBHFunc
*cb
, QCowAIOCB
*acb
)
374 acb
->bh
= qemu_bh_new(cb
, acb
);
378 qemu_bh_schedule(acb
->bh
);
383 static void qcow_aio_read_cb(void *opaque
, int ret
)
385 QCowAIOCB
*acb
= opaque
;
386 BlockDriverState
*bs
= acb
->common
.bs
;
387 BDRVQcowState
*s
= bs
->opaque
;
388 int index_in_cluster
, n1
;
390 acb
->hd_aiocb
= NULL
;
394 /* post process the read buffer */
395 if (!acb
->cluster_offset
) {
397 } else if (acb
->cluster_offset
& QCOW_OFLAG_COMPRESSED
) {
400 if (s
->crypt_method
) {
401 qcow2_encrypt_sectors(s
, acb
->sector_num
, acb
->buf
, acb
->buf
,
403 &s
->aes_decrypt_key
);
407 acb
->nb_sectors
-= acb
->n
;
408 acb
->sector_num
+= acb
->n
;
409 acb
->buf
+= acb
->n
* 512;
411 if (acb
->nb_sectors
== 0) {
412 /* request completed */
417 /* prepare next AIO request */
418 acb
->n
= acb
->nb_sectors
;
419 acb
->cluster_offset
=
420 qcow2_get_cluster_offset(bs
, acb
->sector_num
<< 9, &acb
->n
);
421 index_in_cluster
= acb
->sector_num
& (s
->cluster_sectors
- 1);
423 if (!acb
->cluster_offset
) {
424 if (bs
->backing_hd
) {
425 /* read from the base image */
426 n1
= qcow2_backing_read1(bs
->backing_hd
, acb
->sector_num
,
429 acb
->hd_iov
.iov_base
= (void *)acb
->buf
;
430 acb
->hd_iov
.iov_len
= acb
->n
* 512;
431 qemu_iovec_init_external(&acb
->hd_qiov
, &acb
->hd_iov
, 1);
432 acb
->hd_aiocb
= bdrv_aio_readv(bs
->backing_hd
, acb
->sector_num
,
433 &acb
->hd_qiov
, acb
->n
,
434 qcow_aio_read_cb
, acb
);
435 if (acb
->hd_aiocb
== NULL
)
438 ret
= qcow_schedule_bh(qcow_aio_read_bh
, acb
);
443 /* Note: in this case, no need to wait */
444 memset(acb
->buf
, 0, 512 * acb
->n
);
445 ret
= qcow_schedule_bh(qcow_aio_read_bh
, acb
);
449 } else if (acb
->cluster_offset
& QCOW_OFLAG_COMPRESSED
) {
450 /* add AIO support for compressed blocks ? */
451 if (qcow2_decompress_cluster(s
, acb
->cluster_offset
) < 0)
454 s
->cluster_cache
+ index_in_cluster
* 512, 512 * acb
->n
);
455 ret
= qcow_schedule_bh(qcow_aio_read_bh
, acb
);
459 if ((acb
->cluster_offset
& 511) != 0) {
464 acb
->hd_iov
.iov_base
= (void *)acb
->buf
;
465 acb
->hd_iov
.iov_len
= acb
->n
* 512;
466 qemu_iovec_init_external(&acb
->hd_qiov
, &acb
->hd_iov
, 1);
467 acb
->hd_aiocb
= bdrv_aio_readv(s
->hd
,
468 (acb
->cluster_offset
>> 9) + index_in_cluster
,
469 &acb
->hd_qiov
, acb
->n
, qcow_aio_read_cb
, acb
);
470 if (acb
->hd_aiocb
== NULL
)
476 if (acb
->qiov
->niov
> 1) {
477 qemu_iovec_from_buffer(acb
->qiov
, acb
->orig_buf
, acb
->qiov
->size
);
478 qemu_vfree(acb
->orig_buf
);
480 acb
->common
.cb(acb
->common
.opaque
, ret
);
481 qemu_aio_release(acb
);
484 static QCowAIOCB
*qcow_aio_setup(BlockDriverState
*bs
,
485 int64_t sector_num
, QEMUIOVector
*qiov
, int nb_sectors
,
486 BlockDriverCompletionFunc
*cb
, void *opaque
, int is_write
)
490 acb
= qemu_aio_get(&qcow_aio_pool
, bs
, cb
, opaque
);
493 acb
->hd_aiocb
= NULL
;
494 acb
->sector_num
= sector_num
;
496 if (qiov
->niov
> 1) {
497 acb
->buf
= acb
->orig_buf
= qemu_blockalign(bs
, qiov
->size
);
499 qemu_iovec_to_buffer(qiov
, acb
->buf
);
501 acb
->buf
= (uint8_t *)qiov
->iov
->iov_base
;
503 acb
->nb_sectors
= nb_sectors
;
505 acb
->cluster_offset
= 0;
506 acb
->l2meta
.nb_clusters
= 0;
507 QLIST_INIT(&acb
->l2meta
.dependent_requests
);
511 static BlockDriverAIOCB
*qcow_aio_readv(BlockDriverState
*bs
,
512 int64_t sector_num
, QEMUIOVector
*qiov
, int nb_sectors
,
513 BlockDriverCompletionFunc
*cb
, void *opaque
)
517 acb
= qcow_aio_setup(bs
, sector_num
, qiov
, nb_sectors
, cb
, opaque
, 0);
521 qcow_aio_read_cb(acb
, 0);
525 static void qcow_aio_write_cb(void *opaque
, int ret
);
527 static void run_dependent_requests(QCowL2Meta
*m
)
532 /* Take the request off the list of running requests */
533 if (m
->nb_clusters
!= 0) {
534 QLIST_REMOVE(m
, next_in_flight
);
538 * Restart all dependent requests.
539 * Can't use QLIST_FOREACH here - the next link might not be the same
540 * any more after the callback (request could depend on a different
543 for (req
= m
->dependent_requests
.lh_first
; req
!= NULL
; req
= next
) {
544 next
= req
->next_depend
.le_next
;
545 qcow_aio_write_cb(req
, 0);
548 /* Empty the list for the next part of the request */
549 QLIST_INIT(&m
->dependent_requests
);
552 static void qcow_aio_write_cb(void *opaque
, int ret
)
554 QCowAIOCB
*acb
= opaque
;
555 BlockDriverState
*bs
= acb
->common
.bs
;
556 BDRVQcowState
*s
= bs
->opaque
;
557 int index_in_cluster
;
558 const uint8_t *src_buf
;
561 acb
->hd_aiocb
= NULL
;
564 ret
= qcow2_alloc_cluster_link_l2(bs
, acb
->cluster_offset
, &acb
->l2meta
);
567 run_dependent_requests(&acb
->l2meta
);
572 acb
->nb_sectors
-= acb
->n
;
573 acb
->sector_num
+= acb
->n
;
574 acb
->buf
+= acb
->n
* 512;
576 if (acb
->nb_sectors
== 0) {
577 /* request completed */
582 index_in_cluster
= acb
->sector_num
& (s
->cluster_sectors
- 1);
583 n_end
= index_in_cluster
+ acb
->nb_sectors
;
584 if (s
->crypt_method
&&
585 n_end
> QCOW_MAX_CRYPT_CLUSTERS
* s
->cluster_sectors
)
586 n_end
= QCOW_MAX_CRYPT_CLUSTERS
* s
->cluster_sectors
;
588 acb
->cluster_offset
= qcow2_alloc_cluster_offset(bs
, acb
->sector_num
<< 9,
590 n_end
, &acb
->n
, &acb
->l2meta
);
592 /* Need to wait for another request? If so, we are done for now. */
593 if (!acb
->cluster_offset
&& acb
->l2meta
.depends_on
!= NULL
) {
594 QLIST_INSERT_HEAD(&acb
->l2meta
.depends_on
->dependent_requests
,
599 if (!acb
->cluster_offset
|| (acb
->cluster_offset
& 511) != 0) {
603 if (s
->crypt_method
) {
604 if (!acb
->cluster_data
) {
605 acb
->cluster_data
= qemu_mallocz(QCOW_MAX_CRYPT_CLUSTERS
*
608 qcow2_encrypt_sectors(s
, acb
->sector_num
, acb
->cluster_data
, acb
->buf
,
609 acb
->n
, 1, &s
->aes_encrypt_key
);
610 src_buf
= acb
->cluster_data
;
614 acb
->hd_iov
.iov_base
= (void *)src_buf
;
615 acb
->hd_iov
.iov_len
= acb
->n
* 512;
616 qemu_iovec_init_external(&acb
->hd_qiov
, &acb
->hd_iov
, 1);
617 acb
->hd_aiocb
= bdrv_aio_writev(s
->hd
,
618 (acb
->cluster_offset
>> 9) + index_in_cluster
,
619 &acb
->hd_qiov
, acb
->n
,
620 qcow_aio_write_cb
, acb
);
621 if (acb
->hd_aiocb
== NULL
)
627 if (acb
->qiov
->niov
> 1)
628 qemu_vfree(acb
->orig_buf
);
629 acb
->common
.cb(acb
->common
.opaque
, ret
);
630 qemu_aio_release(acb
);
633 static BlockDriverAIOCB
*qcow_aio_writev(BlockDriverState
*bs
,
634 int64_t sector_num
, QEMUIOVector
*qiov
, int nb_sectors
,
635 BlockDriverCompletionFunc
*cb
, void *opaque
)
637 BDRVQcowState
*s
= bs
->opaque
;
640 s
->cluster_cache_offset
= -1; /* disable compressed cache */
642 acb
= qcow_aio_setup(bs
, sector_num
, qiov
, nb_sectors
, cb
, opaque
, 1);
646 qcow_aio_write_cb(acb
, 0);
650 static void qcow_close(BlockDriverState
*bs
)
652 BDRVQcowState
*s
= bs
->opaque
;
653 qemu_free(s
->l1_table
);
654 qemu_free(s
->l2_cache
);
655 qemu_free(s
->cluster_cache
);
656 qemu_free(s
->cluster_data
);
657 qcow2_refcount_close(bs
);
662 * Updates the variable length parts of the qcow2 header, i.e. the backing file
663 * name and all extensions. qcow2 was not designed to allow such changes, so if
664 * we run out of space (we can only use the first cluster) this function may
667 * Returns 0 on success, -errno in error cases.
669 static int qcow2_update_ext_header(BlockDriverState
*bs
,
670 const char *backing_file
, const char *backing_fmt
)
672 size_t backing_file_len
= 0;
673 size_t backing_fmt_len
= 0;
674 BDRVQcowState
*s
= bs
->opaque
;
675 QCowExtension ext_backing_fmt
= {0, 0};
678 /* Backing file format doesn't make sense without a backing file */
679 if (backing_fmt
&& !backing_file
) {
683 /* Prepare the backing file format extension if needed */
685 ext_backing_fmt
.len
= cpu_to_be32(strlen(backing_fmt
));
686 ext_backing_fmt
.magic
= cpu_to_be32(QCOW_EXT_MAGIC_BACKING_FORMAT
);
687 backing_fmt_len
= ((sizeof(ext_backing_fmt
)
688 + strlen(backing_fmt
) + 7) & ~7);
691 /* Check if we can fit the new header into the first cluster */
693 backing_file_len
= strlen(backing_file
);
696 size_t header_size
= sizeof(QCowHeader
) + backing_file_len
699 if (header_size
> s
->cluster_size
) {
703 /* Rewrite backing file name and qcow2 extensions */
704 size_t ext_size
= header_size
- sizeof(QCowHeader
);
705 uint8_t buf
[ext_size
];
707 size_t backing_file_offset
= 0;
711 int padding
= backing_fmt_len
-
712 (sizeof(ext_backing_fmt
) + strlen(backing_fmt
));
714 memcpy(buf
+ offset
, &ext_backing_fmt
, sizeof(ext_backing_fmt
));
715 offset
+= sizeof(ext_backing_fmt
);
717 memcpy(buf
+ offset
, backing_fmt
, strlen(backing_fmt
));
718 offset
+= strlen(backing_fmt
);
720 memset(buf
+ offset
, 0, padding
);
724 memcpy(buf
+ offset
, backing_file
, backing_file_len
);
725 backing_file_offset
= sizeof(QCowHeader
) + offset
;
728 ret
= bdrv_pwrite(s
->hd
, sizeof(QCowHeader
), buf
, ext_size
);
733 /* Update header fields */
734 uint64_t be_backing_file_offset
= cpu_to_be64(backing_file_offset
);
735 uint32_t be_backing_file_size
= cpu_to_be32(backing_file_len
);
737 ret
= bdrv_pwrite(s
->hd
, offsetof(QCowHeader
, backing_file_offset
),
738 &be_backing_file_offset
, sizeof(uint64_t));
743 ret
= bdrv_pwrite(s
->hd
, offsetof(QCowHeader
, backing_file_size
),
744 &be_backing_file_size
, sizeof(uint32_t));
754 static int qcow2_change_backing_file(BlockDriverState
*bs
,
755 const char *backing_file
, const char *backing_fmt
)
757 return qcow2_update_ext_header(bs
, backing_file
, backing_fmt
);
760 static int get_bits_from_size(size_t size
)
769 /* Not a power of two */
782 static int preallocate(BlockDriverState
*bs
)
784 BDRVQcowState
*s
= bs
->opaque
;
785 uint64_t cluster_offset
= 0;
791 nb_sectors
= bdrv_getlength(bs
) >> 9;
793 QLIST_INIT(&meta
.dependent_requests
);
796 num
= MIN(nb_sectors
, INT_MAX
>> 9);
797 cluster_offset
= qcow2_alloc_cluster_offset(bs
, offset
, 0, num
, &num
,
800 if (cluster_offset
== 0) {
804 if (qcow2_alloc_cluster_link_l2(bs
, cluster_offset
, &meta
) < 0) {
805 qcow2_free_any_clusters(bs
, cluster_offset
, meta
.nb_clusters
);
809 /* There are no dependent requests, but we need to remove our request
810 * from the list of in-flight requests */
811 run_dependent_requests(&meta
);
813 /* TODO Preallocate data if requested */
820 * It is expected that the image file is large enough to actually contain
821 * all of the allocated clusters (otherwise we get failing reads after
822 * EOF). Extend the image to the last allocated sector.
824 if (cluster_offset
!= 0) {
827 bdrv_write(s
->hd
, (cluster_offset
>> 9) + num
- 1, buf
, 1);
833 static int qcow_create2(const char *filename
, int64_t total_size
,
834 const char *backing_file
, const char *backing_format
,
835 int flags
, size_t cluster_size
, int prealloc
)
838 int fd
, header_size
, backing_filename_len
, l1_size
, i
, shift
, l2_bits
;
839 int ref_clusters
, backing_format_len
= 0;
840 int rounded_ext_bf_len
= 0;
842 uint64_t tmp
, offset
;
843 QCowCreateState s1
, *s
= &s1
;
844 QCowExtension ext_bf
= {0, 0};
847 memset(s
, 0, sizeof(*s
));
849 fd
= open(filename
, O_WRONLY
| O_CREAT
| O_TRUNC
| O_BINARY
, 0644);
852 memset(&header
, 0, sizeof(header
));
853 header
.magic
= cpu_to_be32(QCOW_MAGIC
);
854 header
.version
= cpu_to_be32(QCOW_VERSION
);
855 header
.size
= cpu_to_be64(total_size
* 512);
856 header_size
= sizeof(header
);
857 backing_filename_len
= 0;
859 if (backing_format
) {
860 ext_bf
.magic
= QCOW_EXT_MAGIC_BACKING_FORMAT
;
861 backing_format_len
= strlen(backing_format
);
862 ext_bf
.len
= backing_format_len
;
863 rounded_ext_bf_len
= (sizeof(ext_bf
) + ext_bf
.len
+ 7) & ~7;
864 header_size
+= rounded_ext_bf_len
;
866 header
.backing_file_offset
= cpu_to_be64(header_size
);
867 backing_filename_len
= strlen(backing_file
);
868 header
.backing_file_size
= cpu_to_be32(backing_filename_len
);
869 header_size
+= backing_filename_len
;
873 s
->cluster_bits
= get_bits_from_size(cluster_size
);
874 if (s
->cluster_bits
< MIN_CLUSTER_BITS
||
875 s
->cluster_bits
> MAX_CLUSTER_BITS
)
877 fprintf(stderr
, "Cluster size must be a power of two between "
879 1 << MIN_CLUSTER_BITS
,
880 1 << (MAX_CLUSTER_BITS
- 10));
883 s
->cluster_size
= 1 << s
->cluster_bits
;
885 header
.cluster_bits
= cpu_to_be32(s
->cluster_bits
);
886 header_size
= (header_size
+ 7) & ~7;
887 if (flags
& BLOCK_FLAG_ENCRYPT
) {
888 header
.crypt_method
= cpu_to_be32(QCOW_CRYPT_AES
);
890 header
.crypt_method
= cpu_to_be32(QCOW_CRYPT_NONE
);
892 l2_bits
= s
->cluster_bits
- 3;
893 shift
= s
->cluster_bits
+ l2_bits
;
894 l1_size
= (((total_size
* 512) + (1LL << shift
) - 1) >> shift
);
895 offset
= align_offset(header_size
, s
->cluster_size
);
896 s
->l1_table_offset
= offset
;
897 header
.l1_table_offset
= cpu_to_be64(s
->l1_table_offset
);
898 header
.l1_size
= cpu_to_be32(l1_size
);
899 offset
+= align_offset(l1_size
* sizeof(uint64_t), s
->cluster_size
);
901 s
->refcount_table
= qemu_mallocz(s
->cluster_size
);
903 s
->refcount_table_offset
= offset
;
904 header
.refcount_table_offset
= cpu_to_be64(offset
);
905 header
.refcount_table_clusters
= cpu_to_be32(1);
906 offset
+= s
->cluster_size
;
907 s
->refcount_block_offset
= offset
;
909 /* count how many refcount blocks needed */
910 tmp
= offset
>> s
->cluster_bits
;
911 ref_clusters
= (tmp
>> (s
->cluster_bits
- REFCOUNT_SHIFT
)) + 1;
912 for (i
=0; i
< ref_clusters
; i
++) {
913 s
->refcount_table
[i
] = cpu_to_be64(offset
);
914 offset
+= s
->cluster_size
;
917 s
->refcount_block
= qemu_mallocz(ref_clusters
* s
->cluster_size
);
919 /* update refcounts */
920 qcow2_create_refcount_update(s
, 0, header_size
);
921 qcow2_create_refcount_update(s
, s
->l1_table_offset
,
922 l1_size
* sizeof(uint64_t));
923 qcow2_create_refcount_update(s
, s
->refcount_table_offset
, s
->cluster_size
);
924 qcow2_create_refcount_update(s
, s
->refcount_block_offset
,
925 ref_clusters
* s
->cluster_size
);
927 /* write all the data */
928 write(fd
, &header
, sizeof(header
));
930 if (backing_format_len
) {
932 int padding
= rounded_ext_bf_len
- (ext_bf
.len
+ sizeof(ext_bf
));
934 memset(zero
, 0, sizeof(zero
));
935 cpu_to_be32s(&ext_bf
.magic
);
936 cpu_to_be32s(&ext_bf
.len
);
937 write(fd
, &ext_bf
, sizeof(ext_bf
));
938 write(fd
, backing_format
, backing_format_len
);
940 write(fd
, zero
, padding
);
943 write(fd
, backing_file
, backing_filename_len
);
945 lseek(fd
, s
->l1_table_offset
, SEEK_SET
);
947 for(i
= 0;i
< l1_size
; i
++) {
948 write(fd
, &tmp
, sizeof(tmp
));
950 lseek(fd
, s
->refcount_table_offset
, SEEK_SET
);
951 write(fd
, s
->refcount_table
, s
->cluster_size
);
953 lseek(fd
, s
->refcount_block_offset
, SEEK_SET
);
954 write(fd
, s
->refcount_block
, ref_clusters
* s
->cluster_size
);
956 qemu_free(s
->refcount_table
);
957 qemu_free(s
->refcount_block
);
960 /* Preallocate metadata */
962 BlockDriverState
*bs
;
964 bdrv_open(bs
, filename
, BDRV_O_CACHE_WB
);
972 static int qcow_create(const char *filename
, QEMUOptionParameter
*options
)
974 const char *backing_file
= NULL
;
975 const char *backing_fmt
= NULL
;
976 uint64_t sectors
= 0;
978 size_t cluster_size
= 65536;
981 /* Read out options */
982 while (options
&& options
->name
) {
983 if (!strcmp(options
->name
, BLOCK_OPT_SIZE
)) {
984 sectors
= options
->value
.n
/ 512;
985 } else if (!strcmp(options
->name
, BLOCK_OPT_BACKING_FILE
)) {
986 backing_file
= options
->value
.s
;
987 } else if (!strcmp(options
->name
, BLOCK_OPT_BACKING_FMT
)) {
988 backing_fmt
= options
->value
.s
;
989 } else if (!strcmp(options
->name
, BLOCK_OPT_ENCRYPT
)) {
990 flags
|= options
->value
.n
? BLOCK_FLAG_ENCRYPT
: 0;
991 } else if (!strcmp(options
->name
, BLOCK_OPT_CLUSTER_SIZE
)) {
992 if (options
->value
.n
) {
993 cluster_size
= options
->value
.n
;
995 } else if (!strcmp(options
->name
, BLOCK_OPT_PREALLOC
)) {
996 if (!options
->value
.s
|| !strcmp(options
->value
.s
, "off")) {
998 } else if (!strcmp(options
->value
.s
, "metadata")) {
1001 fprintf(stderr
, "Invalid preallocation mode: '%s'\n",
1009 if (backing_file
&& prealloc
) {
1010 fprintf(stderr
, "Backing file and preallocation cannot be used at "
1015 return qcow_create2(filename
, sectors
, backing_file
, backing_fmt
, flags
,
1016 cluster_size
, prealloc
);
1019 static int qcow_make_empty(BlockDriverState
*bs
)
1022 /* XXX: not correct */
1023 BDRVQcowState
*s
= bs
->opaque
;
1024 uint32_t l1_length
= s
->l1_size
* sizeof(uint64_t);
1027 memset(s
->l1_table
, 0, l1_length
);
1028 if (bdrv_pwrite(s
->hd
, s
->l1_table_offset
, s
->l1_table
, l1_length
) < 0)
1030 ret
= bdrv_truncate(s
->hd
, s
->l1_table_offset
+ l1_length
);
1039 /* XXX: put compressed sectors first, then all the cluster aligned
1040 tables to avoid losing bytes in alignment */
1041 static int qcow_write_compressed(BlockDriverState
*bs
, int64_t sector_num
,
1042 const uint8_t *buf
, int nb_sectors
)
1044 BDRVQcowState
*s
= bs
->opaque
;
1048 uint64_t cluster_offset
;
1050 if (nb_sectors
== 0) {
1051 /* align end of file to a sector boundary to ease reading with
1052 sector based I/Os */
1053 cluster_offset
= bdrv_getlength(s
->hd
);
1054 cluster_offset
= (cluster_offset
+ 511) & ~511;
1055 bdrv_truncate(s
->hd
, cluster_offset
);
1059 if (nb_sectors
!= s
->cluster_sectors
)
1062 out_buf
= qemu_malloc(s
->cluster_size
+ (s
->cluster_size
/ 1000) + 128);
1064 /* best compression, small window, no zlib header */
1065 memset(&strm
, 0, sizeof(strm
));
1066 ret
= deflateInit2(&strm
, Z_DEFAULT_COMPRESSION
,
1068 9, Z_DEFAULT_STRATEGY
);
1074 strm
.avail_in
= s
->cluster_size
;
1075 strm
.next_in
= (uint8_t *)buf
;
1076 strm
.avail_out
= s
->cluster_size
;
1077 strm
.next_out
= out_buf
;
1079 ret
= deflate(&strm
, Z_FINISH
);
1080 if (ret
!= Z_STREAM_END
&& ret
!= Z_OK
) {
1085 out_len
= strm
.next_out
- out_buf
;
1089 if (ret
!= Z_STREAM_END
|| out_len
>= s
->cluster_size
) {
1090 /* could not compress: write normal cluster */
1091 bdrv_write(bs
, sector_num
, buf
, s
->cluster_sectors
);
1093 cluster_offset
= qcow2_alloc_compressed_cluster_offset(bs
,
1094 sector_num
<< 9, out_len
);
1095 if (!cluster_offset
)
1097 cluster_offset
&= s
->cluster_offset_mask
;
1098 if (bdrv_pwrite(s
->hd
, cluster_offset
, out_buf
, out_len
) != out_len
) {
1108 static void qcow_flush(BlockDriverState
*bs
)
1110 BDRVQcowState
*s
= bs
->opaque
;
1114 static int64_t qcow_vm_state_offset(BDRVQcowState
*s
)
1116 return (int64_t)s
->l1_vm_state_index
<< (s
->cluster_bits
+ s
->l2_bits
);
1119 static int qcow_get_info(BlockDriverState
*bs
, BlockDriverInfo
*bdi
)
1121 BDRVQcowState
*s
= bs
->opaque
;
1122 bdi
->cluster_size
= s
->cluster_size
;
1123 bdi
->vm_state_offset
= qcow_vm_state_offset(s
);
1128 static int qcow_check(BlockDriverState
*bs
)
1130 return qcow2_check_refcounts(bs
);
1134 static void dump_refcounts(BlockDriverState
*bs
)
1136 BDRVQcowState
*s
= bs
->opaque
;
1137 int64_t nb_clusters
, k
, k1
, size
;
1140 size
= bdrv_getlength(s
->hd
);
1141 nb_clusters
= size_to_clusters(s
, size
);
1142 for(k
= 0; k
< nb_clusters
;) {
1144 refcount
= get_refcount(bs
, k
);
1146 while (k
< nb_clusters
&& get_refcount(bs
, k
) == refcount
)
1148 printf("%lld: refcount=%d nb=%lld\n", k
, refcount
, k
- k1
);
1153 static int qcow_save_vmstate(BlockDriverState
*bs
, const uint8_t *buf
,
1154 int64_t pos
, int size
)
1156 BDRVQcowState
*s
= bs
->opaque
;
1157 int growable
= bs
->growable
;
1160 bdrv_pwrite(bs
, qcow_vm_state_offset(s
) + pos
, buf
, size
);
1161 bs
->growable
= growable
;
1166 static int qcow_load_vmstate(BlockDriverState
*bs
, uint8_t *buf
,
1167 int64_t pos
, int size
)
1169 BDRVQcowState
*s
= bs
->opaque
;
1170 int growable
= bs
->growable
;
1174 ret
= bdrv_pread(bs
, qcow_vm_state_offset(s
) + pos
, buf
, size
);
1175 bs
->growable
= growable
;
1180 static QEMUOptionParameter qcow_create_options
[] = {
1182 .name
= BLOCK_OPT_SIZE
,
1184 .help
= "Virtual disk size"
1187 .name
= BLOCK_OPT_BACKING_FILE
,
1189 .help
= "File name of a base image"
1192 .name
= BLOCK_OPT_BACKING_FMT
,
1194 .help
= "Image format of the base image"
1197 .name
= BLOCK_OPT_ENCRYPT
,
1199 .help
= "Encrypt the image"
1202 .name
= BLOCK_OPT_CLUSTER_SIZE
,
1204 .help
= "qcow2 cluster size"
1207 .name
= BLOCK_OPT_PREALLOC
,
1209 .help
= "Preallocation mode (allowed values: off, metadata)"
1214 static BlockDriver bdrv_qcow2
= {
1215 .format_name
= "qcow2",
1216 .instance_size
= sizeof(BDRVQcowState
),
1217 .bdrv_probe
= qcow_probe
,
1218 .bdrv_open
= qcow_open
,
1219 .bdrv_close
= qcow_close
,
1220 .bdrv_create
= qcow_create
,
1221 .bdrv_flush
= qcow_flush
,
1222 .bdrv_is_allocated
= qcow_is_allocated
,
1223 .bdrv_set_key
= qcow_set_key
,
1224 .bdrv_make_empty
= qcow_make_empty
,
1226 .bdrv_aio_readv
= qcow_aio_readv
,
1227 .bdrv_aio_writev
= qcow_aio_writev
,
1228 .bdrv_write_compressed
= qcow_write_compressed
,
1230 .bdrv_snapshot_create
= qcow2_snapshot_create
,
1231 .bdrv_snapshot_goto
= qcow2_snapshot_goto
,
1232 .bdrv_snapshot_delete
= qcow2_snapshot_delete
,
1233 .bdrv_snapshot_list
= qcow2_snapshot_list
,
1234 .bdrv_get_info
= qcow_get_info
,
1236 .bdrv_save_vmstate
= qcow_save_vmstate
,
1237 .bdrv_load_vmstate
= qcow_load_vmstate
,
1239 .bdrv_change_backing_file
= qcow2_change_backing_file
,
1241 .create_options
= qcow_create_options
,
1242 .bdrv_check
= qcow_check
,
1245 static void bdrv_qcow2_init(void)
1247 bdrv_register(&bdrv_qcow2
);
1250 block_init(bdrv_qcow2_init
);