On 20.05.2015 08:16, Fam Zheng wrote:
Signed-off-by: Fam Zheng <f...@redhat.com> --- blockdev.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)diff --git a/blockdev.c b/blockdev.c index 5eaf77e..7f763d9 100644 --- a/blockdev.c +++ b/blockdev.c @@ -1262,6 +1262,7 @@ typedef struct InternalSnapshotState { BlockDriverState *bs; AioContext *aio_context; QEMUSnapshotInfo sn; + Error *blocker; } InternalSnapshotState;static void internal_snapshot_prepare(BlkTransactionState *common,@@ -1300,6 +1301,10 @@ static void internal_snapshot_prepare(BlkTransactionState *common, state->aio_context = bdrv_get_aio_context(bs); aio_context_acquire(state->aio_context);+ state->bs = bs;+ error_setg(&state->blocker, "internal snapshot in progress"); + bdrv_op_block(bs, BLOCK_OP_TYPE_DEVICE_IO, state->blocker); + if (!bdrv_is_inserted(bs)) { error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, device); return; @@ -1354,9 +1359,6 @@ static void internal_snapshot_prepare(BlkTransactionState *common, name, device); return; } - - /* 4. succeed, mark a snapshot is created */ - state->bs = bs; }
As far as I can see, the failed operation in a transaction is aborted, too. So with this pulled up, if the creation of the snapshot failed, internal_snapshot_abort() will try to delete the (non-existing) snapshot which will fail. What is saving us from an even worse fate (internal_snapshot_prepare() failing because a snapshot with the name already existed, which would then be deleted by internal_snapshot_abort()) is that sn->name will not be set until the snapshot is actually attempted to be taken (thus, bdrv_snapshot_delete() in internal_snapshot_abort() fails). Oh, and that sn->id_str will only be set by bdrv_snapshot_create() in case of success.
So the only visible result is " Konsole output Failed to delete snapshot with id '' and name '' on device 'disk' in abort: Can't find the snapshot".
One way of fixing this would probably to check whether sn->id_str[0] is set instead of state->bs in internal_snapshot_abort(). That is, if bdrv_snapshot_create() really always and only fills sn->id_str if it was successful.
Max
static void internal_snapshot_abort(BlkTransactionState *common)@@ -1387,6 +1389,10 @@ static void internal_snapshot_clean(BlkTransactionState *common) InternalSnapshotState *state = DO_UPCAST(InternalSnapshotState, common, common);+ if (state->bs) {+ bdrv_op_unblock(state->bs, BLOCK_OP_TYPE_DEVICE_IO, state->blocker); + error_free(state->blocker); + } if (state->aio_context) { aio_context_release(state->aio_context); }
