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Copy snapshots out of QCOW2 disk

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In order to backup snapshots, created from QCOW2 iamge, we want to copy snapshots out of QCOW2 disk to a seperate storage.
The following patch adds a new option in "qemu-img": qemu-img convert -f qcow2 -O qcow2 -s snapshot_name src_img bck_img.
Right now, it only supports to copy the full snapshot, delta snapshot is on the way.

Changes from V1: all the comments from Kevin are addressed:
Add read-only checking
Fix coding style
Change the name from bdrv_snapshot_load to bdrv_snapshot_load_tmp

Signed-off-by: Disheng Su <edison@cloud.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
edison 2010-09-21 19:58:41 -07:00 • committed by Kevin Wolf
parent a58b8d5401
commit 51ef67270b
9 changed files with 75 additions and 5 deletions
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31
block/qcow2-snapshot.c
View file

@ -418,3 +418,34 @@ int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
return s->nb_snapshots;
}
int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name)
{
int i, snapshot_index, l1_size2;
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_name);
if (snapshot_index < 0) {
return -ENOENT;
}
sn = &s->snapshots[snapshot_index];
s->l1_size = sn->l1_size;
l1_size2 = s->l1_size * sizeof(uint64_t);
if (s->l1_table != NULL) {
qemu_free(s->l1_table);
}
s->l1_table_offset = sn->l1_table_offset;
s->l1_table = qemu_mallocz(align_offset(l1_size2, 512));
if (bdrv_pread(bs->file, sn->l1_table_offset,
s->l1_table, l1_size2) != l1_size2) {
return -1;
}
for(i = 0;i < s->l1_size; i++) {
be64_to_cpus(&s->l1_table[i]);
}
return 0;
}