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qemu-patch-raspberry4/block/qcow2.c
Kevin Wolf 75bab85ca0 qcow2: Keep unknown header extension when rewriting header 
If we want header extensions to work as compatible extensions, we can't
destroy yet unknown header extensions when rewriting the header (e.g.
for changing the backing file). Save all unknown header extensions in a
list of blobs and include them in a new header.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-02-09 16:17:51 +01:00

1395 lines
40 KiB
C
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/*
* Block driver for the QCOW version 2 format
*
* Copyright (c) 2004-2006 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu-common.h"
#include "block_int.h"
#include "module.h"
#include <zlib.h>
#include "aes.h"
#include "block/qcow2.h"
#include "qemu-error.h"
#include "qerror.h"
/*
Differences with QCOW:
- Support for multiple incremental snapshots.
- Memory management by reference counts.
- Clusters which have a reference count of one have the bit
QCOW_OFLAG_COPIED to optimize write performance.
- Size of compressed clusters is stored in sectors to reduce bit usage
in the cluster offsets.
- Support for storing additional data (such as the VM state) in the
snapshots.
- If a backing store is used, the cluster size is not constrained
(could be backported to QCOW).
- L2 tables have always a size of one cluster.
*/
typedef struct {
uint32_t magic;
uint32_t len;
} QCowExtension;
#define QCOW2_EXT_MAGIC_END 0
#define QCOW2_EXT_MAGIC_BACKING_FORMAT 0xE2792ACA
static int qcow2_probe(const uint8_t *buf, int buf_size, const char *filename)
{
const QCowHeader *cow_header = (const void *)buf;
if (buf_size >= sizeof(QCowHeader) &&
be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
be32_to_cpu(cow_header->version) >= QCOW_VERSION)
return 100;
else
return 0;
}
/*
* read qcow2 extension and fill bs
* start reading from start_offset
* finish reading upon magic of value 0 or when end_offset reached
* unknown magic is skipped (future extension this version knows nothing about)
* return 0 upon success, non-0 otherwise
*/
static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset,
uint64_t end_offset)
{
BDRVQcowState *s = bs->opaque;
QCowExtension ext;
uint64_t offset;
int ret;
#ifdef DEBUG_EXT
printf("qcow2_read_extensions: start=%ld end=%ld\n", start_offset, end_offset);
#endif
offset = start_offset;
while (offset < end_offset) {
#ifdef DEBUG_EXT
BDRVQcowState *s = bs->opaque;
/* Sanity check */
if (offset > s->cluster_size)
printf("qcow2_read_extension: suspicious offset %lu\n", offset);
printf("attempting to read extended header in offset %lu\n", offset);
#endif
if (bdrv_pread(bs->file, offset, &ext, sizeof(ext)) != sizeof(ext)) {
fprintf(stderr, "qcow2_read_extension: ERROR: "
"pread fail from offset %" PRIu64 "\n",
offset);
return 1;
}
be32_to_cpus(&ext.magic);
be32_to_cpus(&ext.len);
offset += sizeof(ext);
#ifdef DEBUG_EXT
printf("ext.magic = 0x%x\n", ext.magic);
#endif
switch (ext.magic) {
case QCOW2_EXT_MAGIC_END:
return 0;
case QCOW2_EXT_MAGIC_BACKING_FORMAT:
if (ext.len >= sizeof(bs->backing_format)) {
fprintf(stderr, "ERROR: ext_backing_format: len=%u too large"
" (>=%zu)\n",
ext.len, sizeof(bs->backing_format));
return 2;
}
if (bdrv_pread(bs->file, offset , bs->backing_format,
ext.len) != ext.len)
return 3;
bs->backing_format[ext.len] = '\0';
#ifdef DEBUG_EXT
printf("Qcow2: Got format extension %s\n", bs->backing_format);
#endif
offset = ((offset + ext.len + 7) & ~7);
break;
default:
/* unknown magic - save it in case we need to rewrite the header */
{
Qcow2UnknownHeaderExtension *uext;
uext = g_malloc0(sizeof(*uext) + ext.len);
uext->magic = ext.magic;
uext->len = ext.len;
QLIST_INSERT_HEAD(&s->unknown_header_ext, uext, next);
ret = bdrv_pread(bs->file, offset , uext->data, uext->len);
if (ret < 0) {
return ret;
}
offset = ((offset + ext.len + 7) & ~7);
}
break;
}
}
return 0;
}
static void cleanup_unknown_header_ext(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
Qcow2UnknownHeaderExtension *uext, *next;
QLIST_FOREACH_SAFE(uext, &s->unknown_header_ext, next, next) {
QLIST_REMOVE(uext, next);
g_free(uext);
}
}
static int qcow2_open(BlockDriverState *bs, int flags)
{
BDRVQcowState *s = bs->opaque;
int len, i, ret = 0;
QCowHeader header;
uint64_t ext_end;
bool writethrough;
ret = bdrv_pread(bs->file, 0, &header, sizeof(header));
if (ret < 0) {
goto fail;
}
be32_to_cpus(&header.magic);
be32_to_cpus(&header.version);
be64_to_cpus(&header.backing_file_offset);
be32_to_cpus(&header.backing_file_size);
be64_to_cpus(&header.size);
be32_to_cpus(&header.cluster_bits);
be32_to_cpus(&header.crypt_method);
be64_to_cpus(&header.l1_table_offset);
be32_to_cpus(&header.l1_size);
be64_to_cpus(&header.refcount_table_offset);
be32_to_cpus(&header.refcount_table_clusters);
be64_to_cpus(&header.snapshots_offset);
be32_to_cpus(&header.nb_snapshots);
if (header.magic != QCOW_MAGIC) {
ret = -EINVAL;
goto fail;
}
if (header.version != QCOW_VERSION) {
char version[64];
snprintf(version, sizeof(version), "QCOW version %d", header.version);
qerror_report(QERR_UNKNOWN_BLOCK_FORMAT_FEATURE,
bs->device_name, "qcow2", version);
ret = -ENOTSUP;
goto fail;
}
if (header.cluster_bits < MIN_CLUSTER_BITS ||
header.cluster_bits > MAX_CLUSTER_BITS) {
ret = -EINVAL;
goto fail;
}
if (header.crypt_method > QCOW_CRYPT_AES) {
ret = -EINVAL;
goto fail;
}
s->crypt_method_header = header.crypt_method;
if (s->crypt_method_header) {
bs->encrypted = 1;
}
s->cluster_bits = header.cluster_bits;
s->cluster_size = 1 << s->cluster_bits;
s->cluster_sectors = 1 << (s->cluster_bits - 9);
s->l2_bits = s->cluster_bits - 3; /* L2 is always one cluster */
s->l2_size = 1 << s->l2_bits;
bs->total_sectors = header.size / 512;
s->csize_shift = (62 - (s->cluster_bits - 8));
s->csize_mask = (1 << (s->cluster_bits - 8)) - 1;
s->cluster_offset_mask = (1LL << s->csize_shift) - 1;
s->refcount_table_offset = header.refcount_table_offset;
s->refcount_table_size =
header.refcount_table_clusters << (s->cluster_bits - 3);
s->snapshots_offset = header.snapshots_offset;
s->nb_snapshots = header.nb_snapshots;
/* read the level 1 table */
s->l1_size = header.l1_size;
s->l1_vm_state_index = size_to_l1(s, header.size);
/* the L1 table must contain at least enough entries to put
header.size bytes */
if (s->l1_size < s->l1_vm_state_index) {
ret = -EINVAL;
goto fail;
}
s->l1_table_offset = header.l1_table_offset;
if (s->l1_size > 0) {
s->l1_table = g_malloc0(
align_offset(s->l1_size * sizeof(uint64_t), 512));
ret = bdrv_pread(bs->file, s->l1_table_offset, s->l1_table,
s->l1_size * sizeof(uint64_t));
if (ret < 0) {
goto fail;
}
for(i = 0;i < s->l1_size; i++) {
be64_to_cpus(&s->l1_table[i]);
}
}
/* alloc L2 table/refcount block cache */
writethrough = ((flags & BDRV_O_CACHE_WB) == 0);
s->l2_table_cache = qcow2_cache_create(bs, L2_CACHE_SIZE, writethrough);
s->refcount_block_cache = qcow2_cache_create(bs, REFCOUNT_CACHE_SIZE,
writethrough);
s->cluster_cache = g_malloc(s->cluster_size);
/* one more sector for decompressed data alignment */
s->cluster_data = qemu_blockalign(bs, QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size
+ 512);
s->cluster_cache_offset = -1;
s->flags = flags;
ret = qcow2_refcount_init(bs);
if (ret != 0) {
goto fail;
}
QLIST_INIT(&s->cluster_allocs);
/* read qcow2 extensions */
if (header.backing_file_offset) {
ext_end = header.backing_file_offset;
} else {
ext_end = s->cluster_size;
}
if (qcow2_read_extensions(bs, sizeof(header), ext_end)) {
ret = -EINVAL;
goto fail;
}
/* read the backing file name */
if (header.backing_file_offset != 0) {
len = header.backing_file_size;
if (len > 1023) {
len = 1023;
}
ret = bdrv_pread(bs->file, header.backing_file_offset,
bs->backing_file, len);
if (ret < 0) {
goto fail;
}
bs->backing_file[len] = '\0';
}
ret = qcow2_read_snapshots(bs);
if (ret < 0) {
goto fail;
}
/* Initialise locks */
qemu_co_mutex_init(&s->lock);
#ifdef DEBUG_ALLOC
{
BdrvCheckResult result = {0};
qcow2_check_refcounts(bs, &result);
}
#endif
return ret;
fail:
cleanup_unknown_header_ext(bs);
qcow2_free_snapshots(bs);
qcow2_refcount_close(bs);
g_free(s->l1_table);
if (s->l2_table_cache) {
qcow2_cache_destroy(bs, s->l2_table_cache);
}
g_free(s->cluster_cache);
qemu_vfree(s->cluster_data);
return ret;
}
static int qcow2_set_key(BlockDriverState *bs, const char *key)
{
BDRVQcowState *s = bs->opaque;
uint8_t keybuf[16];
int len, i;
memset(keybuf, 0, 16);
len = strlen(key);
if (len > 16)
len = 16;
/* XXX: we could compress the chars to 7 bits to increase
entropy */
for(i = 0;i < len;i++) {
keybuf[i] = key[i];
}
s->crypt_method = s->crypt_method_header;
if (AES_set_encrypt_key(keybuf, 128, &s->aes_encrypt_key) != 0)
return -1;
if (AES_set_decrypt_key(keybuf, 128, &s->aes_decrypt_key) != 0)
return -1;
#if 0
/* test */
{
uint8_t in[16];
uint8_t out[16];
uint8_t tmp[16];
for(i=0;i<16;i++)
in[i] = i;
AES_encrypt(in, tmp, &s->aes_encrypt_key);
AES_decrypt(tmp, out, &s->aes_decrypt_key);
for(i = 0; i < 16; i++)
printf(" %02x", tmp[i]);
printf("\n");
for(i = 0; i < 16; i++)
printf(" %02x", out[i]);
printf("\n");
}
#endif
return 0;
}
static int coroutine_fn qcow2_co_is_allocated(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, int *pnum)
{
BDRVQcowState *s = bs->opaque;
uint64_t cluster_offset;
int ret;
*pnum = nb_sectors;
/* FIXME We can get errors here, but the bdrv_co_is_allocated interface
* can't pass them on today */
qemu_co_mutex_lock(&s->lock);
ret = qcow2_get_cluster_offset(bs, sector_num << 9, pnum, &cluster_offset);
qemu_co_mutex_unlock(&s->lock);
if (ret < 0) {
*pnum = 0;
}
return (cluster_offset != 0);
}
/* handle reading after the end of the backing file */
int qcow2_backing_read1(BlockDriverState *bs, QEMUIOVector *qiov,
int64_t sector_num, int nb_sectors)
{
int n1;
if ((sector_num + nb_sectors) <= bs->total_sectors)
return nb_sectors;
if (sector_num >= bs->total_sectors)
n1 = 0;
else
n1 = bs->total_sectors - sector_num;
qemu_iovec_memset_skip(qiov, 0, 512 * (nb_sectors - n1), 512 * n1);
return n1;
}
static coroutine_fn int qcow2_co_readv(BlockDriverState *bs, int64_t sector_num,
int remaining_sectors, QEMUIOVector *qiov)
{
BDRVQcowState *s = bs->opaque;
int index_in_cluster, n1;
int ret;
int cur_nr_sectors; /* number of sectors in current iteration */
uint64_t cluster_offset = 0;
uint64_t bytes_done = 0;
QEMUIOVector hd_qiov;
uint8_t *cluster_data = NULL;
qemu_iovec_init(&hd_qiov, qiov->niov);
qemu_co_mutex_lock(&s->lock);
while (remaining_sectors != 0) {
/* prepare next request */
cur_nr_sectors = remaining_sectors;
if (s->crypt_method) {
cur_nr_sectors = MIN(cur_nr_sectors,
QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors);
}
ret = qcow2_get_cluster_offset(bs, sector_num << 9,
&cur_nr_sectors, &cluster_offset);
if (ret < 0) {
goto fail;
}
index_in_cluster = sector_num & (s->cluster_sectors - 1);
qemu_iovec_reset(&hd_qiov);
qemu_iovec_copy(&hd_qiov, qiov, bytes_done,
cur_nr_sectors * 512);
if (!cluster_offset) {
if (bs->backing_hd) {
/* read from the base image */
n1 = qcow2_backing_read1(bs->backing_hd, &hd_qiov,
sector_num, cur_nr_sectors);
if (n1 > 0) {
BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
qemu_co_mutex_unlock(&s->lock);
ret = bdrv_co_readv(bs->backing_hd, sector_num,
n1, &hd_qiov);
qemu_co_mutex_lock(&s->lock);
if (ret < 0) {
goto fail;
}
}
} else {
/* Note: in this case, no need to wait */
qemu_iovec_memset(&hd_qiov, 0, 512 * cur_nr_sectors);
}
} else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
/* add AIO support for compressed blocks ? */
ret = qcow2_decompress_cluster(bs, cluster_offset);
if (ret < 0) {
goto fail;
}
qemu_iovec_from_buffer(&hd_qiov,
s->cluster_cache + index_in_cluster * 512,
512 * cur_nr_sectors);
} else {
if ((cluster_offset & 511) != 0) {
ret = -EIO;
goto fail;
}
if (s->crypt_method) {
/*
* For encrypted images, read everything into a temporary
* contiguous buffer on which the AES functions can work.
*/
if (!cluster_data) {
cluster_data =
qemu_blockalign(bs, QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
}
assert(cur_nr_sectors <=
QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors);
qemu_iovec_reset(&hd_qiov);
qemu_iovec_add(&hd_qiov, cluster_data,
512 * cur_nr_sectors);
}
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
qemu_co_mutex_unlock(&s->lock);
ret = bdrv_co_readv(bs->file,
(cluster_offset >> 9) + index_in_cluster,
cur_nr_sectors, &hd_qiov);
qemu_co_mutex_lock(&s->lock);
if (ret < 0) {
goto fail;
}
if (s->crypt_method) {
qcow2_encrypt_sectors(s, sector_num, cluster_data,
cluster_data, cur_nr_sectors, 0, &s->aes_decrypt_key);
qemu_iovec_reset(&hd_qiov);
qemu_iovec_copy(&hd_qiov, qiov, bytes_done,
cur_nr_sectors * 512);
qemu_iovec_from_buffer(&hd_qiov, cluster_data,
512 * cur_nr_sectors);
}
}
remaining_sectors -= cur_nr_sectors;
sector_num += cur_nr_sectors;
bytes_done += cur_nr_sectors * 512;
}
ret = 0;
fail:
qemu_co_mutex_unlock(&s->lock);
qemu_iovec_destroy(&hd_qiov);
qemu_vfree(cluster_data);
return ret;
}
static void run_dependent_requests(BDRVQcowState *s, QCowL2Meta *m)
{
/* Take the request off the list of running requests */
if (m->nb_clusters != 0) {
QLIST_REMOVE(m, next_in_flight);
}
/* Restart all dependent requests */
if (!qemu_co_queue_empty(&m->dependent_requests)) {
qemu_co_mutex_unlock(&s->lock);
qemu_co_queue_restart_all(&m->dependent_requests);
qemu_co_mutex_lock(&s->lock);
}
}
static coroutine_fn int qcow2_co_writev(BlockDriverState *bs,
int64_t sector_num,
int remaining_sectors,
QEMUIOVector *qiov)
{
BDRVQcowState *s = bs->opaque;
int index_in_cluster;
int n_end;
int ret;
int cur_nr_sectors; /* number of sectors in current iteration */
uint64_t cluster_offset;
QEMUIOVector hd_qiov;
uint64_t bytes_done = 0;
uint8_t *cluster_data = NULL;
QCowL2Meta l2meta = {
.nb_clusters = 0,
};
qemu_co_queue_init(&l2meta.dependent_requests);
qemu_iovec_init(&hd_qiov, qiov->niov);
s->cluster_cache_offset = -1; /* disable compressed cache */
qemu_co_mutex_lock(&s->lock);
while (remaining_sectors != 0) {
index_in_cluster = sector_num & (s->cluster_sectors - 1);
n_end = index_in_cluster + remaining_sectors;
if (s->crypt_method &&
n_end > QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors) {
n_end = QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors;
}
ret = qcow2_alloc_cluster_offset(bs, sector_num << 9,
index_in_cluster, n_end, &cur_nr_sectors, &l2meta);
if (ret < 0) {
goto fail;
}
cluster_offset = l2meta.cluster_offset;
assert((cluster_offset & 511) == 0);
qemu_iovec_reset(&hd_qiov);
qemu_iovec_copy(&hd_qiov, qiov, bytes_done,
cur_nr_sectors * 512);
if (s->crypt_method) {
if (!cluster_data) {
cluster_data = qemu_blockalign(bs, QCOW_MAX_CRYPT_CLUSTERS *
s->cluster_size);
}
assert(hd_qiov.size <=
QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
qemu_iovec_to_buffer(&hd_qiov, cluster_data);
qcow2_encrypt_sectors(s, sector_num, cluster_data,
cluster_data, cur_nr_sectors, 1, &s->aes_encrypt_key);
qemu_iovec_reset(&hd_qiov);
qemu_iovec_add(&hd_qiov, cluster_data,
cur_nr_sectors * 512);
}
BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
qemu_co_mutex_unlock(&s->lock);
ret = bdrv_co_writev(bs->file,
(cluster_offset >> 9) + index_in_cluster,
cur_nr_sectors, &hd_qiov);
qemu_co_mutex_lock(&s->lock);
if (ret < 0) {
goto fail;
}
ret = qcow2_alloc_cluster_link_l2(bs, &l2meta);
if (ret < 0) {
goto fail;
}
run_dependent_requests(s, &l2meta);
remaining_sectors -= cur_nr_sectors;
sector_num += cur_nr_sectors;
bytes_done += cur_nr_sectors * 512;
}
ret = 0;
fail:
run_dependent_requests(s, &l2meta);
qemu_co_mutex_unlock(&s->lock);
qemu_iovec_destroy(&hd_qiov);
qemu_vfree(cluster_data);
return ret;
}
static void qcow2_close(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
g_free(s->l1_table);
qcow2_cache_flush(bs, s->l2_table_cache);
qcow2_cache_flush(bs, s->refcount_block_cache);
qcow2_cache_destroy(bs, s->l2_table_cache);
qcow2_cache_destroy(bs, s->refcount_block_cache);
cleanup_unknown_header_ext(bs);
g_free(s->cluster_cache);
qemu_vfree(s->cluster_data);
qcow2_refcount_close(bs);
qcow2_free_snapshots(bs);
}
static void qcow2_invalidate_cache(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
int flags = s->flags;
AES_KEY aes_encrypt_key;
AES_KEY aes_decrypt_key;
uint32_t crypt_method = 0;
/*
* Backing files are read-only which makes all of their metadata immutable,
* that means we don't have to worry about reopening them here.
*/
if (s->crypt_method) {
crypt_method = s->crypt_method;
memcpy(&aes_encrypt_key, &s->aes_encrypt_key, sizeof(aes_encrypt_key));
memcpy(&aes_decrypt_key, &s->aes_decrypt_key, sizeof(aes_decrypt_key));
}
qcow2_close(bs);
memset(s, 0, sizeof(BDRVQcowState));
qcow2_open(bs, flags);
if (crypt_method) {
s->crypt_method = crypt_method;
memcpy(&s->aes_encrypt_key, &aes_encrypt_key, sizeof(aes_encrypt_key));
memcpy(&s->aes_decrypt_key, &aes_decrypt_key, sizeof(aes_decrypt_key));
}
}
static size_t header_ext_add(char *buf, uint32_t magic, const void *s,
size_t len, size_t buflen)
{
QCowExtension *ext_backing_fmt = (QCowExtension*) buf;
size_t ext_len = sizeof(QCowExtension) + ((len + 7) & ~7);
if (buflen < ext_len) {
return -ENOSPC;
}
*ext_backing_fmt = (QCowExtension) {
.magic = cpu_to_be32(magic),
.len = cpu_to_be32(len),
};
memcpy(buf + sizeof(QCowExtension), s, len);
return ext_len;
}
/*
* Updates the qcow2 header, including the variable length parts of it, i.e.
* the backing file name and all extensions. qcow2 was not designed to allow
* such changes, so if we run out of space (we can only use the first cluster)
* this function may fail.
*
* Returns 0 on success, -errno in error cases.
*/
int qcow2_update_header(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
QCowHeader *header;
char *buf;
size_t buflen = s->cluster_size;
int ret;
uint64_t total_size;
uint32_t refcount_table_clusters;
Qcow2UnknownHeaderExtension *uext;
buf = qemu_blockalign(bs, buflen);
memset(buf, 0, s->cluster_size);
/* Header structure */
header = (QCowHeader*) buf;
if (buflen < sizeof(*header)) {
ret = -ENOSPC;
goto fail;
}
total_size = bs->total_sectors * BDRV_SECTOR_SIZE;
refcount_table_clusters = s->refcount_table_size >> (s->cluster_bits - 3);
*header = (QCowHeader) {
.magic = cpu_to_be32(QCOW_MAGIC),
.version = cpu_to_be32(QCOW_VERSION),
.backing_file_offset = 0,
.backing_file_size = 0,
.cluster_bits = cpu_to_be32(s->cluster_bits),
.size = cpu_to_be64(total_size),
.crypt_method = cpu_to_be32(s->crypt_method_header),
.l1_size = cpu_to_be32(s->l1_size),
.l1_table_offset = cpu_to_be64(s->l1_table_offset),
.refcount_table_offset = cpu_to_be64(s->refcount_table_offset),
.refcount_table_clusters = cpu_to_be32(refcount_table_clusters),
.nb_snapshots = cpu_to_be32(s->nb_snapshots),
.snapshots_offset = cpu_to_be64(s->snapshots_offset),
};
buf += sizeof(*header);
buflen -= sizeof(*header);
/* Backing file format header extension */
if (*bs->backing_format) {
ret = header_ext_add(buf, QCOW2_EXT_MAGIC_BACKING_FORMAT,
bs->backing_format, strlen(bs->backing_format),
buflen);
if (ret < 0) {
goto fail;
}
buf += ret;
buflen -= ret;
}
/* Keep unknown header extensions */
QLIST_FOREACH(uext, &s->unknown_header_ext, next) {
ret = header_ext_add(buf, uext->magic, uext->data, uext->len, buflen);
if (ret < 0) {
goto fail;
}
buf += ret;
buflen -= ret;
}
/* End of header extensions */
ret = header_ext_add(buf, QCOW2_EXT_MAGIC_END, NULL, 0, buflen);
if (ret < 0) {
goto fail;
}
buf += ret;
buflen -= ret;
/* Backing file name */
if (*bs->backing_file) {
size_t backing_file_len = strlen(bs->backing_file);
if (buflen < backing_file_len) {
ret = -ENOSPC;
goto fail;
}
strncpy(buf, bs->backing_file, buflen);
header->backing_file_offset = cpu_to_be64(buf - ((char*) header));
header->backing_file_size = cpu_to_be32(backing_file_len);
}
/* Write the new header */
ret = bdrv_pwrite(bs->file, 0, header, s->cluster_size);
if (ret < 0) {
goto fail;
}
ret = 0;
fail:
qemu_vfree(header);
return ret;
}
static int qcow2_change_backing_file(BlockDriverState *bs,
const char *backing_file, const char *backing_fmt)
{
/* Backing file format doesn't make sense without a backing file */
if (backing_fmt && !backing_file) {
return -EINVAL;
}
pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");
return qcow2_update_header(bs);
}
static int preallocate(BlockDriverState *bs)
{
uint64_t nb_sectors;
uint64_t offset;
int num;
int ret;
QCowL2Meta meta;
nb_sectors = bdrv_getlength(bs) >> 9;
offset = 0;
qemu_co_queue_init(&meta.dependent_requests);
meta.cluster_offset = 0;
while (nb_sectors) {
num = MIN(nb_sectors, INT_MAX >> 9);
ret = qcow2_alloc_cluster_offset(bs, offset, 0, num, &num, &meta);
if (ret < 0) {
return ret;
}
ret = qcow2_alloc_cluster_link_l2(bs, &meta);
if (ret < 0) {
qcow2_free_any_clusters(bs, meta.cluster_offset, meta.nb_clusters);
return ret;
}
/* There are no dependent requests, but we need to remove our request
* from the list of in-flight requests */
run_dependent_requests(bs->opaque, &meta);
/* TODO Preallocate data if requested */
nb_sectors -= num;
offset += num << 9;
}
/*
* It is expected that the image file is large enough to actually contain
* all of the allocated clusters (otherwise we get failing reads after
* EOF). Extend the image to the last allocated sector.
*/
if (meta.cluster_offset != 0) {
uint8_t buf[512];
memset(buf, 0, 512);
ret = bdrv_write(bs->file, (meta.cluster_offset >> 9) + num - 1, buf, 1);
if (ret < 0) {
return ret;
}
}
return 0;
}
static int qcow2_create2(const char *filename, int64_t total_size,
const char *backing_file, const char *backing_format,
int flags, size_t cluster_size, int prealloc,
QEMUOptionParameter *options)
{
/* Calculate cluster_bits */
int cluster_bits;
cluster_bits = ffs(cluster_size) - 1;
if (cluster_bits < MIN_CLUSTER_BITS || cluster_bits > MAX_CLUSTER_BITS ||
(1 << cluster_bits) != cluster_size)
{
error_report(
"Cluster size must be a power of two between %d and %dk",
1 << MIN_CLUSTER_BITS, 1 << (MAX_CLUSTER_BITS - 10));
return -EINVAL;
}
/*
* Open the image file and write a minimal qcow2 header.
*
* We keep things simple and start with a zero-sized image. We also
* do without refcount blocks or a L1 table for now. We'll fix the
* inconsistency later.
*
* We do need a refcount table because growing the refcount table means
* allocating two new refcount blocks - the seconds of which would be at
* 2 GB for 64k clusters, and we don't want to have a 2 GB initial file
* size for any qcow2 image.
*/
BlockDriverState* bs;
QCowHeader header;
uint8_t* refcount_table;
int ret;
ret = bdrv_create_file(filename, options);
if (ret < 0) {
return ret;
}
ret = bdrv_file_open(&bs, filename, BDRV_O_RDWR);
if (ret < 0) {
return ret;
}
/* Write the header */
memset(&header, 0, sizeof(header));
header.magic = cpu_to_be32(QCOW_MAGIC);
header.version = cpu_to_be32(QCOW_VERSION);
header.cluster_bits = cpu_to_be32(cluster_bits);
header.size = cpu_to_be64(0);
header.l1_table_offset = cpu_to_be64(0);
header.l1_size = cpu_to_be32(0);
header.refcount_table_offset = cpu_to_be64(cluster_size);
header.refcount_table_clusters = cpu_to_be32(1);
if (flags & BLOCK_FLAG_ENCRYPT) {
header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
} else {
header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
}
ret = bdrv_pwrite(bs, 0, &header, sizeof(header));
if (ret < 0) {
goto out;
}
/* Write an empty refcount table */
refcount_table = g_malloc0(cluster_size);
ret = bdrv_pwrite(bs, cluster_size, refcount_table, cluster_size);
g_free(refcount_table);
if (ret < 0) {
goto out;
}
bdrv_close(bs);
/*
* And now open the image and make it consistent first (i.e. increase the
* refcount of the cluster that is occupied by the header and the refcount
* table)
*/
BlockDriver* drv = bdrv_find_format("qcow2");
assert(drv != NULL);
ret = bdrv_open(bs, filename,
BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH, drv);
if (ret < 0) {
goto out;
}
ret = qcow2_alloc_clusters(bs, 2 * cluster_size);
if (ret < 0) {
goto out;
} else if (ret != 0) {
error_report("Huh, first cluster in empty image is already in use?");
abort();
}
/* Okay, now that we have a valid image, let's give it the right size */
ret = bdrv_truncate(bs, total_size * BDRV_SECTOR_SIZE);
if (ret < 0) {
goto out;
}
/* Want a backing file? There you go.*/
if (backing_file) {
ret = bdrv_change_backing_file(bs, backing_file, backing_format);
if (ret < 0) {
goto out;
}
}
/* And if we're supposed to preallocate metadata, do that now */
if (prealloc) {
ret = preallocate(bs);
if (ret < 0) {
goto out;
}
}
ret = 0;
out:
bdrv_delete(bs);
return ret;
}
static int qcow2_create(const char *filename, QEMUOptionParameter *options)
{
const char *backing_file = NULL;
const char *backing_fmt = NULL;
uint64_t sectors = 0;
int flags = 0;
size_t cluster_size = DEFAULT_CLUSTER_SIZE;
int prealloc = 0;
/* Read out options */
while (options && options->name) {
if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
sectors = options->value.n / 512;
} else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) {
backing_file = options->value.s;
} else if (!strcmp(options->name, BLOCK_OPT_BACKING_FMT)) {
backing_fmt = options->value.s;
} else if (!strcmp(options->name, BLOCK_OPT_ENCRYPT)) {
flags |= options->value.n ? BLOCK_FLAG_ENCRYPT : 0;
} else if (!strcmp(options->name, BLOCK_OPT_CLUSTER_SIZE)) {
if (options->value.n) {
cluster_size = options->value.n;
}
} else if (!strcmp(options->name, BLOCK_OPT_PREALLOC)) {
if (!options->value.s || !strcmp(options->value.s, "off")) {
prealloc = 0;
} else if (!strcmp(options->value.s, "metadata")) {
prealloc = 1;
} else {
fprintf(stderr, "Invalid preallocation mode: '%s'\n",
options->value.s);
return -EINVAL;
}
}
options++;
}
if (backing_file && prealloc) {
fprintf(stderr, "Backing file and preallocation cannot be used at "
"the same time\n");
return -EINVAL;
}
return qcow2_create2(filename, sectors, backing_file, backing_fmt, flags,
cluster_size, prealloc, options);
}
static int qcow2_make_empty(BlockDriverState *bs)
{
#if 0
/* XXX: not correct */
BDRVQcowState *s = bs->opaque;
uint32_t l1_length = s->l1_size * sizeof(uint64_t);
int ret;
memset(s->l1_table, 0, l1_length);
if (bdrv_pwrite(bs->file, s->l1_table_offset, s->l1_table, l1_length) < 0)
return -1;
ret = bdrv_truncate(bs->file, s->l1_table_offset + l1_length);
if (ret < 0)
return ret;
l2_cache_reset(bs);
#endif
return 0;
}
static coroutine_fn int qcow2_co_discard(BlockDriverState *bs,
int64_t sector_num, int nb_sectors)
{
int ret;
BDRVQcowState *s = bs->opaque;
qemu_co_mutex_lock(&s->lock);
ret = qcow2_discard_clusters(bs, sector_num << BDRV_SECTOR_BITS,
nb_sectors);
qemu_co_mutex_unlock(&s->lock);
return ret;
}
static int qcow2_truncate(BlockDriverState *bs, int64_t offset)
{
BDRVQcowState *s = bs->opaque;
int ret, new_l1_size;
if (offset & 511) {
return -EINVAL;
}
/* cannot proceed if image has snapshots */
if (s->nb_snapshots) {
return -ENOTSUP;
}
/* shrinking is currently not supported */
if (offset < bs->total_sectors * 512) {
return -ENOTSUP;
}
new_l1_size = size_to_l1(s, offset);
ret = qcow2_grow_l1_table(bs, new_l1_size, true);
if (ret < 0) {
return ret;
}
/* write updated header.size */
offset = cpu_to_be64(offset);
ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, size),
&offset, sizeof(uint64_t));
if (ret < 0) {
return ret;
}
s->l1_vm_state_index = new_l1_size;
return 0;
}
/* XXX: put compressed sectors first, then all the cluster aligned
tables to avoid losing bytes in alignment */
static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
BDRVQcowState *s = bs->opaque;
z_stream strm;
int ret, out_len;
uint8_t *out_buf;
uint64_t cluster_offset;
if (nb_sectors == 0) {
/* align end of file to a sector boundary to ease reading with
sector based I/Os */
cluster_offset = bdrv_getlength(bs->file);
cluster_offset = (cluster_offset + 511) & ~511;
bdrv_truncate(bs->file, cluster_offset);
return 0;
}
if (nb_sectors != s->cluster_sectors)
return -EINVAL;
out_buf = g_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
/* best compression, small window, no zlib header */
memset(&strm, 0, sizeof(strm));
ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
Z_DEFLATED, -12,
9, Z_DEFAULT_STRATEGY);
if (ret != 0) {
ret = -EINVAL;
goto fail;
}
strm.avail_in = s->cluster_size;
strm.next_in = (uint8_t *)buf;
strm.avail_out = s->cluster_size;
strm.next_out = out_buf;
ret = deflate(&strm, Z_FINISH);
if (ret != Z_STREAM_END && ret != Z_OK) {
deflateEnd(&strm);
ret = -EINVAL;
goto fail;
}
out_len = strm.next_out - out_buf;
deflateEnd(&strm);
if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
/* could not compress: write normal cluster */
ret = bdrv_write(bs, sector_num, buf, s->cluster_sectors);
if (ret < 0) {
goto fail;
}
} else {
cluster_offset = qcow2_alloc_compressed_cluster_offset(bs,
sector_num << 9, out_len);
if (!cluster_offset) {
ret = -EIO;
goto fail;
}
cluster_offset &= s->cluster_offset_mask;
BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED);
ret = bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len);
if (ret < 0) {
goto fail;
}
}
ret = 0;
fail:
g_free(out_buf);
return ret;
}
static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
int ret;
qemu_co_mutex_lock(&s->lock);
ret = qcow2_cache_flush(bs, s->l2_table_cache);
if (ret < 0) {
qemu_co_mutex_unlock(&s->lock);
return ret;
}
ret = qcow2_cache_flush(bs, s->refcount_block_cache);
if (ret < 0) {
qemu_co_mutex_unlock(&s->lock);
return ret;
}
qemu_co_mutex_unlock(&s->lock);
return 0;
}
static coroutine_fn int qcow2_co_flush_to_disk(BlockDriverState *bs)
{
return bdrv_co_flush(bs->file);
}
static int64_t qcow2_vm_state_offset(BDRVQcowState *s)
{
return (int64_t)s->l1_vm_state_index << (s->cluster_bits + s->l2_bits);
}
static int qcow2_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
BDRVQcowState *s = bs->opaque;
bdi->cluster_size = s->cluster_size;
bdi->vm_state_offset = qcow2_vm_state_offset(s);
return 0;
}
static int qcow2_check(BlockDriverState *bs, BdrvCheckResult *result)
{
return qcow2_check_refcounts(bs, result);
}
#if 0
static void dump_refcounts(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
int64_t nb_clusters, k, k1, size;
int refcount;
size = bdrv_getlength(bs->file);
nb_clusters = size_to_clusters(s, size);
for(k = 0; k < nb_clusters;) {
k1 = k;
refcount = get_refcount(bs, k);
k++;
while (k < nb_clusters && get_refcount(bs, k) == refcount)
k++;
printf("%" PRId64 ": refcount=%d nb=%" PRId64 "\n", k, refcount,
k - k1);
}
}
#endif
static int qcow2_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
int64_t pos, int size)
{
BDRVQcowState *s = bs->opaque;
int growable = bs->growable;
int ret;
BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_SAVE);
bs->growable = 1;
ret = bdrv_pwrite(bs, qcow2_vm_state_offset(s) + pos, buf, size);
bs->growable = growable;
return ret;
}
static int qcow2_load_vmstate(BlockDriverState *bs, uint8_t *buf,
int64_t pos, int size)
{
BDRVQcowState *s = bs->opaque;
int growable = bs->growable;
int ret;
BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_LOAD);
bs->growable = 1;
ret = bdrv_pread(bs, qcow2_vm_state_offset(s) + pos, buf, size);
bs->growable = growable;
return ret;
}
static QEMUOptionParameter qcow2_create_options[] = {
{
.name = BLOCK_OPT_SIZE,
.type = OPT_SIZE,
.help = "Virtual disk size"
},
{
.name = BLOCK_OPT_BACKING_FILE,
.type = OPT_STRING,
.help = "File name of a base image"
},
{
.name = BLOCK_OPT_BACKING_FMT,
.type = OPT_STRING,
.help = "Image format of the base image"
},
{
.name = BLOCK_OPT_ENCRYPT,
.type = OPT_FLAG,
.help = "Encrypt the image"
},
{
.name = BLOCK_OPT_CLUSTER_SIZE,
.type = OPT_SIZE,
.help = "qcow2 cluster size",
.value = { .n = DEFAULT_CLUSTER_SIZE },
},
{
.name = BLOCK_OPT_PREALLOC,
.type = OPT_STRING,
.help = "Preallocation mode (allowed values: off, metadata)"
},
{ NULL }
};
static BlockDriver bdrv_qcow2 = {
.format_name = "qcow2",
.instance_size = sizeof(BDRVQcowState),
.bdrv_probe = qcow2_probe,
.bdrv_open = qcow2_open,
.bdrv_close = qcow2_close,
.bdrv_create = qcow2_create,
.bdrv_co_is_allocated = qcow2_co_is_allocated,
.bdrv_set_key = qcow2_set_key,
.bdrv_make_empty = qcow2_make_empty,
.bdrv_co_readv = qcow2_co_readv,
.bdrv_co_writev = qcow2_co_writev,
.bdrv_co_flush_to_os = qcow2_co_flush_to_os,
.bdrv_co_flush_to_disk = qcow2_co_flush_to_disk,
.bdrv_co_discard = qcow2_co_discard,
.bdrv_truncate = qcow2_truncate,
.bdrv_write_compressed = qcow2_write_compressed,
.bdrv_snapshot_create = qcow2_snapshot_create,
.bdrv_snapshot_goto = qcow2_snapshot_goto,
.bdrv_snapshot_delete = qcow2_snapshot_delete,
.bdrv_snapshot_list = qcow2_snapshot_list,
.bdrv_snapshot_load_tmp = qcow2_snapshot_load_tmp,
.bdrv_get_info = qcow2_get_info,
.bdrv_save_vmstate = qcow2_save_vmstate,
.bdrv_load_vmstate = qcow2_load_vmstate,
.bdrv_change_backing_file = qcow2_change_backing_file,
.bdrv_invalidate_cache = qcow2_invalidate_cache,
.create_options = qcow2_create_options,
.bdrv_check = qcow2_check,
};
static void bdrv_qcow2_init(void)
{
bdrv_register(&bdrv_qcow2);
}
block_init(bdrv_qcow2_init);
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