qcow2: Version 3 images
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>
diff --git a/block/qcow2.c b/block/qcow2.c
index 4c82adc..3e1482f 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -61,7 +61,7 @@
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 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 @@
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 @@
} 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 @@
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 @@
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 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 @@
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 @@
.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 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 @@
/* 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 @@
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 @@
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 @@
}
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)
@@ -1341,6 +1454,11 @@
.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,
.help = "File name of a base image"
