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qcow2: Fix order in qcow2_snapshot_delete 

First the snapshot must be deleted and only then the refcounts can be
decreased.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
This commit is contained in:
Kevin Wolf 2011-11-16 17:22:10 +01:00
parent 43a0cac465
commit 9a4767809f
1 changed files with 34 additions and 16 deletions
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50
block/qcow2-snapshot.c
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@ -489,32 +489,50 @@ fail:
int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
{
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
QCowSnapshot sn;
int snapshot_index, ret;
/* Search the snapshot */
snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
if (snapshot_index < 0)
if (snapshot_index < 0) {
return -ENOENT;
sn = &s->snapshots[snapshot_index];
}
sn = s->snapshots[snapshot_index];
ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset, sn->l1_size, -1);
if (ret < 0)
return ret;
/* must update the copied flag on the current cluster offsets */
ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
if (ret < 0)
return ret;
qcow2_free_clusters(bs, sn->l1_table_offset, sn->l1_size * sizeof(uint64_t));
g_free(sn->id_str);
g_free(sn->name);
memmove(sn, sn + 1, (s->nb_snapshots - snapshot_index - 1) * sizeof(*sn));
/* Remove it from the snapshot list */
memmove(s->snapshots + snapshot_index,
s->snapshots + snapshot_index + 1,
(s->nb_snapshots - snapshot_index - 1) * sizeof(sn));
s->nb_snapshots--;
ret = qcow2_write_snapshots(bs);
if (ret < 0) {
/* XXX: restore snapshot if error ? */
return ret;
}
/*
* The snapshot is now unused, clean up. If we fail after this point, we
* won't recover but just leak clusters.
*/
g_free(sn.id_str);
g_free(sn.name);
/*
* Now decrease the refcounts of clusters referenced by the snapshot and
* free the L1 table.
*/
ret = qcow2_update_snapshot_refcount(bs, sn.l1_table_offset,
sn.l1_size, -1);
if (ret < 0) {
return ret;
}
qcow2_free_clusters(bs, sn.l1_table_offset, sn.l1_size * sizeof(uint64_t));
/* must update the copied flag on the current cluster offsets */
ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
if (ret < 0) {
return ret;
}
#ifdef DEBUG_ALLOC
{
BdrvCheckResult result = {0};