On Mon, Sep 09, 2013 at 10:57:57AM +0800, Wenchao Xia wrote:
> Signed-off-by: Wenchao Xia <xiaw...@linux.vnet.ibm.com>
> ---
> block/qcow2-snapshot.c | 7 +++++--
> 1 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
> index 40393b2..9e2d695 100644
> --- a/block/qcow2-snapshot.c
> +++ b/block/qcow2-snapshot.c
> @@ -186,7 +186,7 @@ static int qcow2_write_snapshots(BlockDriverState *bs)
> }
> ret = bdrv_flush(bs);
> if (ret < 0) {
> - return ret;
> + goto fail;
> }
>
> /* The snapshot list position has not yet been updated, so these clusters
> @@ -194,7 +194,7 @@ static int qcow2_write_snapshots(BlockDriverState *bs)
> ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT, offset,
> s->snapshots_size);
> if (ret < 0) {
> - return ret;
> + goto fail;
> }
>
>
> @@ -278,6 +278,9 @@ static int qcow2_write_snapshots(BlockDriverState *bs)
> return 0;
>
> fail:
> + /* free the new snapshot table */
> + qcow2_free_clusters(bs, snapshots_offset, snapshots_size,
> + QCOW2_DISCARD_ALWAYS);
It is safer to skip qcow2_free_clusters() when the final
bdrv_pwrite_sync() fails. We don't know if the header was updated on
disk. If it was updated, then freeing the clusters may allow them to be
reallocated later (this will cause corruption).
