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qcow2: Version 3 images

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This adds the basic infrastructure to qcow2 to handle version 3 images.
It includes code to create v3 images, allow header updates for v3 images
and checks feature bits.

It still misses support for zero clusters, so this is not a fully
compliant implementation of v3 yet.

The default for creating new images stays at v2 for now.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2011-12-15 12:20:58 +01:00
parent afdf0abe77
commit 6744cbab8c
3 changed files with 149 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

146
block/qcow2.c
View File

@ -61,7 +61,7 @@ static int qcow2_probe(const uint8_t *buf, int buf_size, const char *filename)
if (buf_size >= sizeof(QCowHeader) &&
be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
be32_to_cpu(cow_header->version) >= QCOW_VERSION)
be32_to_cpu(cow_header->version) >= 2)
return 100;
else
return 0;
@ -169,6 +169,19 @@ static void cleanup_unknown_header_ext(BlockDriverState *bs)
}
}
static void report_unsupported(BlockDriverState *bs, const char *fmt, ...)
{
char msg[64];
va_list ap;
va_start(ap, fmt);
vsnprintf(msg, sizeof(msg), fmt, ap);
va_end(ap);
qerror_report(QERR_UNKNOWN_BLOCK_FORMAT_FEATURE,
bs->device_name, "qcow2", msg);
}
static int qcow2_open(BlockDriverState *bs, int flags)
{
BDRVQcowState *s = bs->opaque;
@ -199,14 +212,64 @@ static int qcow2_open(BlockDriverState *bs, int flags)
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);
if (header.version < 2 || header.version > 3) {
report_unsupported(bs, "QCOW version %d", header.version);
ret = -ENOTSUP;
goto fail;
}
s->qcow_version = header.version;
/* Initialise version 3 header fields */
if (header.version == 2) {
header.incompatible_features = 0;
header.compatible_features = 0;
header.autoclear_features = 0;
header.refcount_order = 4;
header.header_length = 72;
} else {
be64_to_cpus(&header.incompatible_features);
be64_to_cpus(&header.compatible_features);
be64_to_cpus(&header.autoclear_features);
be32_to_cpus(&header.refcount_order);
be32_to_cpus(&header.header_length);
}
if (header.header_length > sizeof(header)) {
s->unknown_header_fields_size = header.header_length - sizeof(header);
s->unknown_header_fields = g_malloc(s->unknown_header_fields_size);
ret = bdrv_pread(bs->file, sizeof(header), s->unknown_header_fields,
s->unknown_header_fields_size);
if (ret < 0) {
goto fail;
}
}
/* Handle feature bits */
s->incompatible_features = header.incompatible_features;
s->compatible_features = header.compatible_features;
s->autoclear_features = header.autoclear_features;
if (s->incompatible_features != 0) {
report_unsupported(bs, "incompatible features mask %" PRIx64,
header.incompatible_features);
ret = -ENOTSUP;
goto fail;
}
if (!bs->read_only && s->autoclear_features != 0) {
s->autoclear_features = 0;
qcow2_update_header(bs);
}
/* Check support for various header values */
if (header.refcount_order != 4) {
report_unsupported(bs, "%d bit reference counts",
1 << header.refcount_order);
ret = -ENOTSUP;
goto fail;
}
if (header.cluster_bits < MIN_CLUSTER_BITS ||
header.cluster_bits > MAX_CLUSTER_BITS) {
ret = -EINVAL;
@ -285,7 +348,7 @@ static int qcow2_open(BlockDriverState *bs, int flags)
} else {
ext_end = s->cluster_size;
}
if (qcow2_read_extensions(bs, sizeof(header), ext_end)) {
if (qcow2_read_extensions(bs, header.header_length, ext_end)) {
ret = -EINVAL;
goto fail;
}
@ -321,6 +384,7 @@ static int qcow2_open(BlockDriverState *bs, int flags)
return ret;
fail:
g_free(s->unknown_header_fields);
cleanup_unknown_header_ext(bs);
qcow2_free_snapshots(bs);
qcow2_refcount_close(bs);
@ -682,7 +746,9 @@ static void qcow2_close(BlockDriverState *bs)
qcow2_cache_destroy(bs, s->l2_table_cache);
qcow2_cache_destroy(bs, s->refcount_block_cache);
g_free(s->unknown_header_fields);
cleanup_unknown_header_ext(bs);
g_free(s->cluster_cache);
qemu_vfree(s->cluster_data);
qcow2_refcount_close(bs);
@ -756,10 +822,10 @@ int qcow2_update_header(BlockDriverState *bs)
int ret;
uint64_t total_size;
uint32_t refcount_table_clusters;
size_t header_length;
Qcow2UnknownHeaderExtension *uext;
buf = qemu_blockalign(bs, buflen);
memset(buf, 0, s->cluster_size);
/* Header structure */
header = (QCowHeader*) buf;
@ -769,12 +835,14 @@ int qcow2_update_header(BlockDriverState *bs)
goto fail;
}
header_length = sizeof(*header) + s->unknown_header_fields_size;
total_size = bs->total_sectors * BDRV_SECTOR_SIZE;
refcount_table_clusters = s->refcount_table_size >> (s->cluster_bits - 3);
*header = (QCowHeader) {
/* Version 2 fields */
.magic = cpu_to_be32(QCOW_MAGIC),
.version = cpu_to_be32(QCOW_VERSION),
.version = cpu_to_be32(s->qcow_version),
.backing_file_offset = 0,
.backing_file_size = 0,
.cluster_bits = cpu_to_be32(s->cluster_bits),
@ -786,10 +854,42 @@ int qcow2_update_header(BlockDriverState *bs)
.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),
/* Version 3 fields */
.incompatible_features = cpu_to_be64(s->incompatible_features),
.compatible_features = cpu_to_be64(s->compatible_features),
.autoclear_features = cpu_to_be64(s->autoclear_features),
.refcount_order = cpu_to_be32(3 + REFCOUNT_SHIFT),
.header_length = cpu_to_be32(header_length),
};
buf += sizeof(*header);
buflen -= sizeof(*header);
/* For older versions, write a shorter header */
switch (s->qcow_version) {
case 2:
ret = offsetof(QCowHeader, incompatible_features);
break;
case 3:
ret = sizeof(*header);
break;
default:
return -EINVAL;
}
buf += ret;
buflen -= ret;
memset(buf, 0, buflen);
/* Preserve any unknown field in the header */
if (s->unknown_header_fields_size) {
if (buflen < s->unknown_header_fields_size) {
ret = -ENOSPC;
goto fail;
}
memcpy(buf, s->unknown_header_fields, s->unknown_header_fields_size);
buf += s->unknown_header_fields_size;
buflen -= s->unknown_header_fields_size;
}
/* Backing file format header extension */
if (*bs->backing_format) {
@ -921,7 +1021,7 @@ static int preallocate(BlockDriverState *bs)
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)
QEMUOptionParameter *options, int version)
{
/* Calculate cluster_bits */
int cluster_bits;
@ -965,13 +1065,15 @@ static int qcow2_create2(const char *filename, int64_t total_size,
/* Write the header */
memset(&header, 0, sizeof(header));
header.magic = cpu_to_be32(QCOW_MAGIC);
header.version = cpu_to_be32(QCOW_VERSION);
header.version = cpu_to_be32(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);
header.refcount_order = cpu_to_be32(3 + REFCOUNT_SHIFT);
header.header_length = cpu_to_be32(sizeof(header));
if (flags & BLOCK_FLAG_ENCRYPT) {
header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
@ -1053,6 +1155,7 @@ static int qcow2_create(const char *filename, QEMUOptionParameter *options)
int flags = 0;
size_t cluster_size = DEFAULT_CLUSTER_SIZE;
int prealloc = 0;
int version = 2;
/* Read out options */
while (options && options->name) {
@ -1078,6 +1181,16 @@ static int qcow2_create(const char *filename, QEMUOptionParameter *options)
options->value.s);
return -EINVAL;
}
} else if (!strcmp(options->name, BLOCK_OPT_COMPAT_LEVEL)) {
if (!options->value.s || !strcmp(options->value.s, "0.10")) {
version = 2;
} else if (!strcmp(options->value.s, "1.1")) {
version = 3;
} else {
fprintf(stderr, "Invalid compatibility level: '%s'\n",
options->value.s);
return -EINVAL;
}
}
options++;
}
@ -1089,7 +1202,7 @@ static int qcow2_create(const char *filename, QEMUOptionParameter *options)
}
return qcow2_create2(filename, sectors, backing_file, backing_fmt, flags,
cluster_size, prealloc, options);
cluster_size, prealloc, options, version);
}
static int qcow2_make_empty(BlockDriverState *bs)
@ -1340,6 +1453,11 @@ static QEMUOptionParameter qcow2_create_options[] = {
.type = OPT_SIZE,
.help = "Virtual disk size"
},
{
.name = BLOCK_OPT_COMPAT_LEVEL,
.type = OPT_STRING,
.help = "Compatibility level (0.10 or 1.1)"
},
{
.name = BLOCK_OPT_BACKING_FILE,
.type = OPT_STRING,

17
block/qcow2.h
View File

@ -33,7 +33,6 @@
//#define DEBUG_EXT
#define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
#define QCOW_VERSION 2
#define QCOW_CRYPT_NONE 0
#define QCOW_CRYPT_AES 1
@ -71,6 +70,14 @@ typedef struct QCowHeader {
uint32_t refcount_table_clusters;
uint32_t nb_snapshots;
uint64_t snapshots_offset;
/* The following fields are only valid for version >= 3 */
uint64_t incompatible_features;
uint64_t compatible_features;
uint64_t autoclear_features;
uint32_t refcount_order;
uint32_t header_length;
} QCowHeader;
typedef struct QCowSnapshot {
@ -135,6 +142,14 @@ typedef struct BDRVQcowState {
QCowSnapshot *snapshots;
int flags;
int qcow_version;
uint64_t incompatible_features;
uint64_t compatible_features;
uint64_t autoclear_features;
size_t unknown_header_fields_size;
void* unknown_header_fields;
QLIST_HEAD(, Qcow2UnknownHeaderExtension) unknown_header_ext;
} BDRVQcowState;

1
block_int.h
View File

@ -50,6 +50,7 @@
#define BLOCK_OPT_TABLE_SIZE "table_size"
#define BLOCK_OPT_PREALLOC "preallocation"
#define BLOCK_OPT_SUBFMT "subformat"
#define BLOCK_OPT_COMPAT_LEVEL "compat"
typedef struct BdrvTrackedRequest BdrvTrackedRequest;