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[Qemu-devel] [PATCH v2 8/9] qcow2: Fix order in qcow2_snapshot_delete
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH v2 8/9] qcow2: Fix order in qcow2_snapshot_delete |
Date: |
Fri, 18 Nov 2011 19:29:04 +0100 |
First the snapshot must be deleted and only then the refcounts can be
decreased.
Signed-off-by: Kevin Wolf <address@hidden>
---
block/qcow2-snapshot.c | 48 +++++++++++++++++++++++++++++++++---------------
1 files changed, 33 insertions(+), 15 deletions(-)
diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index 20cb66e..d4fbcb9 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -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)
+ /* 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) {
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)
+ }
+
+ /*
+ * 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));
+ }
+ 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));
- s->nb_snapshots--;
- ret = qcow2_write_snapshots(bs);
+ /* 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) {
- /* XXX: restore snapshot if error ? */
return ret;
}
+
#ifdef DEBUG_ALLOC
{
BdrvCheckResult result = {0};
--
1.7.6.4
- [Qemu-devel] [PATCH v2 0/9] qcow2: Fix error paths for internal snapshots, Kevin Wolf, 2011/11/18
- [Qemu-devel] [PATCH v2 4/9] qcow2: Cleanups and memleak fix in qcow2_snapshot_create, Kevin Wolf, 2011/11/18
- [Qemu-devel] [PATCH v2 2/9] qcow2: Return real error code in qcow2_write_snapshots, Kevin Wolf, 2011/11/18
- [Qemu-devel] [PATCH v2 8/9] qcow2: Fix order in qcow2_snapshot_delete,
Kevin Wolf <=
- [Qemu-devel] [PATCH v2 7/9] qcow2: Fix order of refcount updates in qcow2_snapshot_goto, Kevin Wolf, 2011/11/18
- [Qemu-devel] [PATCH v2 9/9] qcow2: Fix error path in qcow2_snapshot_load_tmp, Kevin Wolf, 2011/11/18
- [Qemu-devel] [PATCH v2 6/9] qcow2: Return real error in qcow2_snapshot_goto, Kevin Wolf, 2011/11/18
- Re: [Qemu-devel] [PATCH v2 0/9] qcow2: Fix error paths for internal snapshots, Stefan Hajnoczi, 2011/11/21