Re: [Qemu-block] [PATCH v6 08/13] blockdev: Block device IO during internal snapshot transaction

[Max Reitz]

On 21.05.2015 08:42, Fam Zheng wrote:
> Signed-off-by: Fam Zheng <address@hidden>
> ---
>   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;
>   }

Unchanged from v5, so the same issue: Pulling this up means that 
internal_snapshot_abort() may attempt to delete the snapshot even if it 
hasn't been (successfully) created. This will always fail because 
sn->id_str is empty, though.

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);
>       }