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qemu/block/qcow.c

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/*
* Block driver for the QCOW 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/osdep.h"
#include "qapi/error.h"
#include "qemu-common.h"
#include "qemu/error-report.h"
#include "block/block_int.h"
#include "sysemu/block-backend.h"
#include "qemu/module.h"
#include "qemu/bswap.h"
#include <zlib.h>
#include "qapi/qmp/qerror.h"
#include "crypto/cipher.h"
#include "migration/migration.h"
/**************************************************************/
/* QEMU COW block driver with compression and encryption support */
#define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
#define QCOW_VERSION 1
#define QCOW_CRYPT_NONE 0
#define QCOW_CRYPT_AES 1
#define QCOW_OFLAG_COMPRESSED (1LL << 63)
typedef struct QCowHeader {
uint32_t magic;
uint32_t version;
uint64_t backing_file_offset;
uint32_t backing_file_size;
uint32_t mtime;
uint64_t size; /* in bytes */
uint8_t cluster_bits;
uint8_t l2_bits;
uint16_t padding;
uint32_t crypt_method;
uint64_t l1_table_offset;
} QEMU_PACKED QCowHeader;
#define L2_CACHE_SIZE 16
typedef struct BDRVQcowState {
int cluster_bits;
int cluster_size;
int cluster_sectors;
int l2_bits;
int l2_size;
unsigned int l1_size;
uint64_t cluster_offset_mask;
uint64_t l1_table_offset;
uint64_t *l1_table;
uint64_t *l2_cache;
uint64_t l2_cache_offsets[L2_CACHE_SIZE];
uint32_t l2_cache_counts[L2_CACHE_SIZE];
uint8_t *cluster_cache;
uint8_t *cluster_data;
uint64_t cluster_cache_offset;
QCryptoCipher *cipher; /* NULL if no key yet */
uint32_t crypt_method_header;
CoMutex lock;
Error *migration_blocker;
} BDRVQcowState;
static int decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
static int qcow_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;
}
static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
BDRVQcowState *s = bs->opaque;
unsigned int len, i, shift;
int ret;
QCowHeader header;
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);
be32_to_cpus(&header.mtime);
be64_to_cpus(&header.size);
be32_to_cpus(&header.crypt_method);
be64_to_cpus(&header.l1_table_offset);
if (header.magic != QCOW_MAGIC) {
error_setg(errp, "Image not in qcow format");
ret = -EINVAL;
goto fail;
}
if (header.version != QCOW_VERSION) {
error_setg(errp, "Unsupported qcow version %" PRIu32, header.version);
ret = -ENOTSUP;
goto fail;
}
if (header.size <= 1) {
error_setg(errp, "Image size is too small (must be at least 2 bytes)");
ret = -EINVAL;
goto fail;
}
if (header.cluster_bits < 9 || header.cluster_bits > 16) {
error_setg(errp, "Cluster size must be between 512 and 64k");
ret = -EINVAL;
goto fail;
}
/* l2_bits specifies number of entries; storing a uint64_t in each entry,
* so bytes = num_entries << 3. */
if (header.l2_bits < 9 - 3 || header.l2_bits > 16 - 3) {
error_setg(errp, "L2 table size must be between 512 and 64k");
ret = -EINVAL;
goto fail;
}
if (header.crypt_method > QCOW_CRYPT_AES) {
error_setg(errp, "invalid encryption method in qcow header");
ret = -EINVAL;
goto fail;
}
if (!qcrypto_cipher_supports(QCRYPTO_CIPHER_ALG_AES_128)) {
error_setg(errp, "AES cipher not available");
ret = -EINVAL;
goto fail;
}
s->crypt_method_header = header.crypt_method;
if (s->crypt_method_header) {
if (bdrv_uses_whitelist() &&
s->crypt_method_header == QCOW_CRYPT_AES) {
error_setg(errp,
"Use of AES-CBC encrypted qcow images is no longer "
"supported in system emulators");
error_append_hint(errp,
"You can use 'qemu-img convert' to convert your "
"image to an alternative supported format, such "
"as unencrypted qcow, or raw with the LUKS "
"format instead.\n");
ret = -ENOSYS;
goto fail;
}
bs->encrypted = true;
}
s->cluster_bits = header.cluster_bits;
s->cluster_size = 1 << s->cluster_bits;
s->cluster_sectors = 1 << (s->cluster_bits - 9);
s->l2_bits = header.l2_bits;
s->l2_size = 1 << s->l2_bits;
bs->total_sectors = header.size / 512;
s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1;
/* read the level 1 table */
shift = s->cluster_bits + s->l2_bits;
if (header.size > UINT64_MAX - (1LL << shift)) {
error_setg(errp, "Image too large");
ret = -EINVAL;
goto fail;
} else {
uint64_t l1_size = (header.size + (1LL << shift) - 1) >> shift;
if (l1_size > INT_MAX / sizeof(uint64_t)) {
error_setg(errp, "Image too large");
ret = -EINVAL;
goto fail;
}
s->l1_size = l1_size;
}
s->l1_table_offset = header.l1_table_offset;
s->l1_table = g_try_new(uint64_t, s->l1_size);
if (s->l1_table == NULL) {
error_setg(errp, "Could not allocate memory for L1 table");
ret = -ENOMEM;
goto fail;
}
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 cache (max. 64k * 16 * 8 = 8 MB) */
s->l2_cache =
qemu_try_blockalign(bs->file->bs,
s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
if (s->l2_cache == NULL) {
error_setg(errp, "Could not allocate L2 table cache");
ret = -ENOMEM;
goto fail;
}
s->cluster_cache = g_malloc(s->cluster_size);
s->cluster_data = g_malloc(s->cluster_size);
s->cluster_cache_offset = -1;
/* read the backing file name */
if (header.backing_file_offset != 0) {
len = header.backing_file_size;
if (len > 1023 || len >= sizeof(bs->backing_file)) {
error_setg(errp, "Backing file name too long");
ret = -EINVAL;
goto fail;
}
ret = bdrv_pread(bs->file, header.backing_file_offset,
bs->backing_file, len);
if (ret < 0) {
goto fail;
}
bs->backing_file[len] = '\0';
}
/* Disable migration when qcow images are used */
error_setg(&s->migration_blocker, "The qcow format used by node '%s' "
"does not support live migration",
bdrv_get_device_or_node_name(bs));
migrate_add_blocker(s->migration_blocker);
qemu_co_mutex_init(&s->lock);
return 0;
fail:
g_free(s->l1_table);
qemu_vfree(s->l2_cache);
g_free(s->cluster_cache);
g_free(s->cluster_data);
return ret;
}
/* We have nothing to do for QCOW reopen, stubs just return
* success */
static int qcow_reopen_prepare(BDRVReopenState *state,
BlockReopenQueue *queue, Error **errp)
{
return 0;
}
static int qcow_set_key(BlockDriverState *bs, const char *key)
{
BDRVQcowState *s = bs->opaque;
uint8_t keybuf[16];
int len, i;
Error *err;
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];
}
assert(bs->encrypted);
qcrypto_cipher_free(s->cipher);
s->cipher = qcrypto_cipher_new(
QCRYPTO_CIPHER_ALG_AES_128,
QCRYPTO_CIPHER_MODE_CBC,
keybuf, G_N_ELEMENTS(keybuf),
&err);
if (!s->cipher) {
/* XXX would be nice if errors in this method could
* be properly propagate to the caller. Would need
* the bdrv_set_key() API signature to be fixed. */
error_free(err);
return -1;
}
return 0;
}
/* The crypt function is compatible with the linux cryptoloop
algorithm for < 4 GB images. NOTE: out_buf == in_buf is
supported */
static int encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
uint8_t *out_buf, const uint8_t *in_buf,
int nb_sectors, bool enc, Error **errp)
{
union {
uint64_t ll[2];
uint8_t b[16];
} ivec;
int i;
int ret;
for(i = 0; i < nb_sectors; i++) {
ivec.ll[0] = cpu_to_le64(sector_num);
ivec.ll[1] = 0;
if (qcrypto_cipher_setiv(s->cipher,
ivec.b, G_N_ELEMENTS(ivec.b),
errp) < 0) {
return -1;
}
if (enc) {
ret = qcrypto_cipher_encrypt(s->cipher,
in_buf,
out_buf,
512,
errp);
} else {
ret = qcrypto_cipher_decrypt(s->cipher,
in_buf,
out_buf,
512,
errp);
}
if (ret < 0) {
return -1;
}
sector_num++;
in_buf += 512;
out_buf += 512;
}
return 0;
}
/* 'allocate' is:
*
* 0 to not allocate.
*
* 1 to allocate a normal cluster (for sector indexes 'n_start' to
* 'n_end')
*
* 2 to allocate a compressed cluster of size
* 'compressed_size'. 'compressed_size' must be > 0 and <
* cluster_size
*
* return 0 if not allocated.
*/
static uint64_t get_cluster_offset(BlockDriverState *bs,
uint64_t offset, int allocate,
int compressed_size,
int n_start, int n_end)
{
BDRVQcowState *s = bs->opaque;
int min_index, i, j, l1_index, l2_index;
uint64_t l2_offset, *l2_table, cluster_offset, tmp;
uint32_t min_count;
int new_l2_table;
l1_index = offset >> (s->l2_bits + s->cluster_bits);
l2_offset = s->l1_table[l1_index];
new_l2_table = 0;
if (!l2_offset) {
if (!allocate)
return 0;
/* allocate a new l2 entry */
l2_offset = bdrv_getlength(bs->file->bs);
/* round to cluster size */
l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size - 1);
/* update the L1 entry */
s->l1_table[l1_index] = l2_offset;
tmp = cpu_to_be64(l2_offset);
if (bdrv_pwrite_sync(bs->file,
s->l1_table_offset + l1_index * sizeof(tmp),
&tmp, sizeof(tmp)) < 0)
return 0;
new_l2_table = 1;
}
for(i = 0; i < L2_CACHE_SIZE; i++) {
if (l2_offset == s->l2_cache_offsets[i]) {
/* increment the hit count */
if (++s->l2_cache_counts[i] == 0xffffffff) {
for(j = 0; j < L2_CACHE_SIZE; j++) {
s->l2_cache_counts[j] >>= 1;
}
}
l2_table = s->l2_cache + (i << s->l2_bits);
goto found;
}
}
/* not found: load a new entry in the least used one */
min_index = 0;
min_count = 0xffffffff;
for(i = 0; i < L2_CACHE_SIZE; i++) {
if (s->l2_cache_counts[i] < min_count) {
min_count = s->l2_cache_counts[i];
min_index = i;
}
}
l2_table = s->l2_cache + (min_index << s->l2_bits);
if (new_l2_table) {
memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
if (bdrv_pwrite_sync(bs->file, l2_offset, l2_table,
s->l2_size * sizeof(uint64_t)) < 0)
return 0;
} else {
if (bdrv_pread(bs->file, l2_offset, l2_table,
s->l2_size * sizeof(uint64_t)) !=
s->l2_size * sizeof(uint64_t))
return 0;
}
s->l2_cache_offsets[min_index] = l2_offset;
s->l2_cache_counts[min_index] = 1;
found:
l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
cluster_offset = be64_to_cpu(l2_table[l2_index]);
if (!cluster_offset ||
((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) {
if (!allocate)
return 0;
/* allocate a new cluster */
if ((cluster_offset & QCOW_OFLAG_COMPRESSED) &&
(n_end - n_start) < s->cluster_sectors) {
/* if the cluster is already compressed, we must
decompress it in the case it is not completely
overwritten */
if (decompress_cluster(bs, cluster_offset) < 0)
return 0;
cluster_offset = bdrv_getlength(bs->file->bs);
cluster_offset = (cluster_offset + s->cluster_size - 1) &
~(s->cluster_size - 1);
/* write the cluster content */
if (bdrv_pwrite(bs->file, cluster_offset, s->cluster_cache,
s->cluster_size) !=
s->cluster_size)
return -1;
} else {
cluster_offset = bdrv_getlength(bs->file->bs);
if (allocate == 1) {
/* round to cluster size */
cluster_offset = (cluster_offset + s->cluster_size - 1) &
~(s->cluster_size - 1);
bdrv_truncate(bs->file->bs, cluster_offset + s->cluster_size);
/* if encrypted, we must initialize the cluster
content which won't be written */
if (bs->encrypted &&
(n_end - n_start) < s->cluster_sectors) {
uint64_t start_sect;
assert(s->cipher);
start_sect = (offset & ~(s->cluster_size - 1)) >> 9;
memset(s->cluster_data + 512, 0x00, 512);
for(i = 0; i < s->cluster_sectors; i++) {
if (i < n_start || i >= n_end) {
Error *err = NULL;
if (encrypt_sectors(s, start_sect + i,
s->cluster_data,
s->cluster_data + 512, 1,
true, &err) < 0) {
error_free(err);
errno = EIO;
return -1;
}
if (bdrv_pwrite(bs->file,
cluster_offset + i * 512,
s->cluster_data, 512) != 512)
return -1;
}
}
}
} else if (allocate == 2) {
cluster_offset |= QCOW_OFLAG_COMPRESSED |
(uint64_t)compressed_size << (63 - s->cluster_bits);
}
}
/* update L2 table */
tmp = cpu_to_be64(cluster_offset);
l2_table[l2_index] = tmp;
if (bdrv_pwrite_sync(bs->file, l2_offset + l2_index * sizeof(tmp),
&tmp, sizeof(tmp)) < 0)
return 0;
}
return cluster_offset;
}
static int64_t coroutine_fn qcow_co_get_block_status(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, int *pnum, BlockDriverState **file)
{
BDRVQcowState *s = bs->opaque;
int index_in_cluster, n;
uint64_t cluster_offset;
qemu_co_mutex_lock(&s->lock);
cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
qemu_co_mutex_unlock(&s->lock);
index_in_cluster = sector_num & (s->cluster_sectors - 1);
n = s->cluster_sectors - index_in_cluster;
if (n > nb_sectors)
n = nb_sectors;
*pnum = n;
if (!cluster_offset) {
return 0;
}
if ((cluster_offset & QCOW_OFLAG_COMPRESSED) || s->cipher) {
return BDRV_BLOCK_DATA;
}
cluster_offset |= (index_in_cluster << BDRV_SECTOR_BITS);
*file = bs->file->bs;
return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | cluster_offset;
}
static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
const uint8_t *buf, int buf_size)
{
z_stream strm1, *strm = &strm1;
int ret, out_len;
memset(strm, 0, sizeof(*strm));
strm->next_in = (uint8_t *)buf;
strm->avail_in = buf_size;
strm->next_out = out_buf;
strm->avail_out = out_buf_size;
ret = inflateInit2(strm, -12);
if (ret != Z_OK)
return -1;
ret = inflate(strm, Z_FINISH);
out_len = strm->next_out - out_buf;
if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
out_len != out_buf_size) {
inflateEnd(strm);
return -1;
}
inflateEnd(strm);
return 0;
}
static int decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
{
BDRVQcowState *s = bs->opaque;
int ret, csize;
uint64_t coffset;
coffset = cluster_offset & s->cluster_offset_mask;
if (s->cluster_cache_offset != coffset) {
csize = cluster_offset >> (63 - s->cluster_bits);
csize &= (s->cluster_size - 1);
ret = bdrv_pread(bs->file, coffset, s->cluster_data, csize);
if (ret != csize)
return -1;
if (decompress_buffer(s->cluster_cache, s->cluster_size,
s->cluster_data, csize) < 0) {
return -1;
}
s->cluster_cache_offset = coffset;
}
return 0;
}
static coroutine_fn int qcow_co_readv(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
{
BDRVQcowState *s = bs->opaque;
int index_in_cluster;
int ret = 0, n;
uint64_t cluster_offset;
struct iovec hd_iov;
QEMUIOVector hd_qiov;
uint8_t *buf;
void *orig_buf;
Error *err = NULL;
if (qiov->niov > 1) {
buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
if (buf == NULL) {
return -ENOMEM;
}
} else {
orig_buf = NULL;
buf = (uint8_t *)qiov->iov->iov_base;
}
qemu_co_mutex_lock(&s->lock);
while (nb_sectors != 0) {
/* prepare next request */
cluster_offset = get_cluster_offset(bs, sector_num << 9,
0, 0, 0, 0);
index_in_cluster = sector_num & (s->cluster_sectors - 1);
n = s->cluster_sectors - index_in_cluster;
if (n > nb_sectors) {
n = nb_sectors;
}
if (!cluster_offset) {
if (bs->backing) {
/* read from the base image */
hd_iov.iov_base = (void *)buf;
hd_iov.iov_len = n * 512;
qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
qemu_co_mutex_unlock(&s->lock);
ret = bdrv_co_readv(bs->backing, sector_num, n, &hd_qiov);
qemu_co_mutex_lock(&s->lock);
if (ret < 0) {
goto fail;
}
} else {
/* Note: in this case, no need to wait */
memset(buf, 0, 512 * n);
}
} else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
/* add AIO support for compressed blocks ? */
if (decompress_cluster(bs, cluster_offset) < 0) {
goto fail;
}
memcpy(buf,
s->cluster_cache + index_in_cluster * 512, 512 * n);
} else {
if ((cluster_offset & 511) != 0) {
goto fail;
}
hd_iov.iov_base = (void *)buf;
hd_iov.iov_len = n * 512;
qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
qemu_co_mutex_unlock(&s->lock);
ret = bdrv_co_readv(bs->file,
(cluster_offset >> 9) + index_in_cluster,
n, &hd_qiov);
qemu_co_mutex_lock(&s->lock);
if (ret < 0) {
break;
}
if (bs->encrypted) {
assert(s->cipher);
if (encrypt_sectors(s, sector_num, buf, buf,
n, false, &err) < 0) {
goto fail;
}
}
}
ret = 0;
nb_sectors -= n;
sector_num += n;
buf += n * 512;
}
done:
qemu_co_mutex_unlock(&s->lock);
if (qiov->niov > 1) {
qemu_iovec_from_buf(qiov, 0, orig_buf, qiov->size);
qemu_vfree(orig_buf);
}
return ret;
fail:
error_free(err);
ret = -EIO;
goto done;
}
static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
{
BDRVQcowState *s = bs->opaque;
int index_in_cluster;
uint64_t cluster_offset;
const uint8_t *src_buf;
int ret = 0, n;
uint8_t *cluster_data = NULL;
struct iovec hd_iov;
QEMUIOVector hd_qiov;
uint8_t *buf;
void *orig_buf;
s->cluster_cache_offset = -1; /* disable compressed cache */
if (qiov->niov > 1) {
buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
if (buf == NULL) {
return -ENOMEM;
}
qemu_iovec_to_buf(qiov, 0, buf, qiov->size);
} else {
orig_buf = NULL;
buf = (uint8_t *)qiov->iov->iov_base;
}
qemu_co_mutex_lock(&s->lock);
while (nb_sectors != 0) {
index_in_cluster = sector_num & (s->cluster_sectors - 1);
n = s->cluster_sectors - index_in_cluster;
if (n > nb_sectors) {
n = nb_sectors;
}
cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0,
index_in_cluster,
index_in_cluster + n);
if (!cluster_offset || (cluster_offset & 511) != 0) {
ret = -EIO;
break;
}
if (bs->encrypted) {
Error *err = NULL;
assert(s->cipher);
if (!cluster_data) {
cluster_data = g_malloc0(s->cluster_size);
}
if (encrypt_sectors(s, sector_num, cluster_data, buf,
n, true, &err) < 0) {
error_free(err);
ret = -EIO;
break;
}
src_buf = cluster_data;
} else {
src_buf = buf;
}
hd_iov.iov_base = (void *)src_buf;
hd_iov.iov_len = n * 512;
qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
qemu_co_mutex_unlock(&s->lock);
ret = bdrv_co_writev(bs->file,
(cluster_offset >> 9) + index_in_cluster,
n, &hd_qiov);
qemu_co_mutex_lock(&s->lock);
if (ret < 0) {
break;
}
ret = 0;
nb_sectors -= n;
sector_num += n;
buf += n * 512;
}
qemu_co_mutex_unlock(&s->lock);
if (qiov->niov > 1) {
qemu_vfree(orig_buf);
}
g_free(cluster_data);
return ret;
}
static void qcow_close(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
qcrypto_cipher_free(s->cipher);
s->cipher = NULL;
g_free(s->l1_table);
qemu_vfree(s->l2_cache);
g_free(s->cluster_cache);
g_free(s->cluster_data);
migrate_del_blocker(s->migration_blocker);
error_free(s->migration_blocker);
}
static int qcow_create(const char *filename, QemuOpts *opts, Error **errp)
{
int header_size, backing_filename_len, l1_size, shift, i;
QCowHeader header;
uint8_t *tmp;
int64_t total_size = 0;
char *backing_file = NULL;
int flags = 0;
Error *local_err = NULL;
int ret;
BlockBackend *qcow_blk;
/* Read out options */
total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
BDRV_SECTOR_SIZE);
backing_file = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FILE);
if (qemu_opt_get_bool_del(opts, BLOCK_OPT_ENCRYPT, false)) {
flags |= BLOCK_FLAG_ENCRYPT;
}
ret = bdrv_create_file(filename, opts, &local_err);
if (ret < 0) {
error_propagate(errp, local_err);
goto cleanup;
}
qcow_blk = blk_new_open(filename, NULL, NULL,
BDRV_O_RDWR | BDRV_O_PROTOCOL, &local_err);
if (qcow_blk == NULL) {
error_propagate(errp, local_err);
ret = -EIO;
goto cleanup;
}
blk_set_allow_write_beyond_eof(qcow_blk, true);
ret = blk_truncate(qcow_blk, 0);
if (ret < 0) {
goto exit;
}
memset(&header, 0, sizeof(header));
header.magic = cpu_to_be32(QCOW_MAGIC);
header.version = cpu_to_be32(QCOW_VERSION);
header.size = cpu_to_be64(total_size);
header_size = sizeof(header);
backing_filename_len = 0;
if (backing_file) {
if (strcmp(backing_file, "fat:")) {
header.backing_file_offset = cpu_to_be64(header_size);
backing_filename_len = strlen(backing_file);
header.backing_file_size = cpu_to_be32(backing_filename_len);
header_size += backing_filename_len;
} else {
/* special backing file for vvfat */
backing_file = NULL;
}
header.cluster_bits = 9; /* 512 byte cluster to avoid copying
unmodified sectors */
header.l2_bits = 12; /* 32 KB L2 tables */
} else {
header.cluster_bits = 12; /* 4 KB clusters */
header.l2_bits = 9; /* 4 KB L2 tables */
}
header_size = (header_size + 7) & ~7;
shift = header.cluster_bits + header.l2_bits;
l1_size = (total_size + (1LL << shift) - 1) >> shift;
header.l1_table_offset = cpu_to_be64(header_size);
if (flags & BLOCK_FLAG_ENCRYPT) {
header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
} else {
header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
}
/* write all the data */
ret = blk_pwrite(qcow_blk, 0, &header, sizeof(header), 0);
if (ret != sizeof(header)) {
goto exit;
}
if (backing_file) {
ret = blk_pwrite(qcow_blk, sizeof(header),
backing_file, backing_filename_len, 0);
if (ret != backing_filename_len) {
goto exit;
}
}
tmp = g_malloc0(BDRV_SECTOR_SIZE);
for (i = 0; i < DIV_ROUND_UP(sizeof(uint64_t) * l1_size, BDRV_SECTOR_SIZE);
i++) {
ret = blk_pwrite(qcow_blk, header_size + BDRV_SECTOR_SIZE * i,
tmp, BDRV_SECTOR_SIZE, 0);
if (ret != BDRV_SECTOR_SIZE) {
g_free(tmp);
goto exit;
}
}
g_free(tmp);
ret = 0;
exit:
blk_unref(qcow_blk);
cleanup:
g_free(backing_file);
return ret;
}
static int qcow_make_empty(BlockDriverState *bs)
{
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_sync(bs->file, s->l1_table_offset, s->l1_table,
l1_length) < 0)
return -1;
ret = bdrv_truncate(bs->file->bs, s->l1_table_offset + l1_length);
if (ret < 0)
return ret;
memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
return 0;
}
/* XXX: put compressed sectors first, then all the cluster aligned
tables to avoid losing bytes in alignment */
static coroutine_fn int
qcow_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov)
{
BDRVQcowState *s = bs->opaque;
QEMUIOVector hd_qiov;
struct iovec iov;
z_stream strm;
int ret, out_len;
uint8_t *buf, *out_buf;
uint64_t cluster_offset;
buf = qemu_blockalign(bs, s->cluster_size);
if (bytes != s->cluster_size) {
if (bytes > s->cluster_size ||
offset + bytes != bs->total_sectors << BDRV_SECTOR_BITS)
{
qemu_vfree(buf);
return -EINVAL;
}
/* Zero-pad last write if image size is not cluster aligned */
memset(buf + bytes, 0, s->cluster_size - bytes);
}
qemu_iovec_to_buf(qiov, 0, buf, qiov->size);
out_buf = g_malloc(s->cluster_size);
/* 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 = qcow_co_writev(bs, offset >> BDRV_SECTOR_BITS,
bytes >> BDRV_SECTOR_BITS, qiov);
if (ret < 0) {
goto fail;
}
goto success;
}
qemu_co_mutex_lock(&s->lock);
cluster_offset = get_cluster_offset(bs, offset, 2, out_len, 0, 0);
qemu_co_mutex_unlock(&s->lock);
if (cluster_offset == 0) {
ret = -EIO;
goto fail;
}
cluster_offset &= s->cluster_offset_mask;
iov = (struct iovec) {
.iov_base = out_buf,
.iov_len = out_len,
};
qemu_iovec_init_external(&hd_qiov, &iov, 1);
ret = bdrv_co_pwritev(bs->file, cluster_offset, out_len, &hd_qiov, 0);
if (ret < 0) {
goto fail;
}
success:
ret = 0;
fail:
qemu_vfree(buf);
g_free(out_buf);
return ret;
}
static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
BDRVQcowState *s = bs->opaque;
bdi->cluster_size = s->cluster_size;
return 0;
}
static QemuOptsList qcow_create_opts = {
.name = "qcow-create-opts",
.head = QTAILQ_HEAD_INITIALIZER(qcow_create_opts.head),
.desc = {
{
.name = BLOCK_OPT_SIZE,
.type = QEMU_OPT_SIZE,
.help = "Virtual disk size"
},
{
.name = BLOCK_OPT_BACKING_FILE,
.type = QEMU_OPT_STRING,
.help = "File name of a base image"
},
{
.name = BLOCK_OPT_ENCRYPT,
.type = QEMU_OPT_BOOL,
.help = "Encrypt the image",
.def_value_str = "off"
},
{ /* end of list */ }
}
};
static BlockDriver bdrv_qcow = {
.format_name = "qcow",
.instance_size = sizeof(BDRVQcowState),
.bdrv_probe = qcow_probe,
.bdrv_open = qcow_open,
.bdrv_close = qcow_close,
.bdrv_reopen_prepare = qcow_reopen_prepare,
.bdrv_create = qcow_create,
.bdrv_has_zero_init = bdrv_has_zero_init_1,
.supports_backing = true,
.bdrv_co_readv = qcow_co_readv,
.bdrv_co_writev = qcow_co_writev,
.bdrv_co_get_block_status = qcow_co_get_block_status,
.bdrv_set_key = qcow_set_key,
.bdrv_make_empty = qcow_make_empty,
.bdrv_co_pwritev_compressed = qcow_co_pwritev_compressed,
.bdrv_get_info = qcow_get_info,
.create_opts = &qcow_create_opts,
};
static void bdrv_qcow_init(void)
{
bdrv_register(&bdrv_qcow);
}
block_init(bdrv_qcow_init);
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