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qcow2: Creating images with external data file

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This adds a .bdrv_create option to use an external data file.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2019-01-14 16:57:27 +01:00
parent 0e8c08be27
commit dcc98687f8
3 changed files with 31 additions and 0 deletions
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26
block/qcow2.c
View File

@ -2880,6 +2880,7 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
*/
BlockBackend *blk = NULL;
BlockDriverState *bs = NULL;
BlockDriverState *data_bs = NULL;
QCowHeader *header;
size_t cluster_size;
int version;
@ -2976,6 +2977,20 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
}
refcount_order = ctz32(qcow2_opts->refcount_bits);
if (qcow2_opts->data_file) {
if (version < 3) {
error_setg(errp, "External data files are only supported with "
"compatibility level 1.1 and above (use version=v3 or "
"greater)");
ret = -EINVAL;
goto out;
}
data_bs = bdrv_open_blockdev_ref(qcow2_opts->data_file, errp);
if (bs == NULL) {
ret = -EIO;
goto out;
}
}
/* Create BlockBackend to write to the image */
blk = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
@ -3014,6 +3029,10 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
header->compatible_features |=
cpu_to_be64(QCOW2_COMPAT_LAZY_REFCOUNTS);
}
if (data_bs) {
header->incompatible_features |=
cpu_to_be64(QCOW2_INCOMPAT_DATA_FILE);
}
ret = blk_pwrite(blk, 0, header, cluster_size, 0);
g_free(header);
@ -3044,6 +3063,9 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
options = qdict_new();
qdict_put_str(options, "driver", "qcow2");
qdict_put_str(options, "file", bs->node_name);
if (data_bs) {
qdict_put_str(options, "data-file", data_bs->node_name);
}
blk = blk_new_open(NULL, NULL, options,
BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_NO_FLUSH,
&local_err);
@ -3116,6 +3138,9 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
options = qdict_new();
qdict_put_str(options, "driver", "qcow2");
qdict_put_str(options, "file", bs->node_name);
if (data_bs) {
qdict_put_str(options, "data-file", data_bs->node_name);
}
blk = blk_new_open(NULL, NULL, options,
BDRV_O_RDWR | BDRV_O_NO_BACKING | BDRV_O_NO_IO,
&local_err);
@ -3129,6 +3154,7 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
out:
blk_unref(blk);
bdrv_unref(bs);
bdrv_unref(data_bs);
return ret;
}

1
include/block/block_int.h
View File

@ -56,6 +56,7 @@
#define BLOCK_OPT_NOCOW "nocow"
#define BLOCK_OPT_OBJECT_SIZE "object_size"
#define BLOCK_OPT_REFCOUNT_BITS "refcount_bits"
#define BLOCK_OPT_DATA_FILE "data_file"
#define BLOCK_PROBE_BUF_SIZE 512

4
qapi/block-core.json
View File

@ -4135,6 +4135,9 @@
# Driver specific image creation options for qcow2.
#
# @file Node to create the image format on
# @data-file Node to use as an external data file in which all guest
# data is stored so that only metadata remains in the qcow2
# file (since: 4.0)
# @size Size of the virtual disk in bytes
# @version Compatibility level (default: v3)
# @backing-file File name of the backing file if a backing file
@ -4150,6 +4153,7 @@
##
{ 'struct': 'BlockdevCreateOptionsQcow2',
'data': { 'file': 'BlockdevRef',
'*data-file': 'BlockdevRef',
'size': 'size',
'*version': 'BlockdevQcow2Version',
'*backing-file': 'str',