On Thu, Oct 22, 2015 at 12:18:11PM +0200, Kevin Wolf wrote:
> Am 22.10.2015 um 08:32 hat Fam Zheng geschrieben:
> > This ensures the atomicity of the transaction by avoiding processing of
> > external requests such as those from ioeventfd.
> >
> > state->bs is assigned right after bdrv_drained_begin. Because it was
> > used as the flag for deletion or not in abort, now we need a separate
> > flag - InternalSnapshotState.created.
> >
> > Signed-off-by: Fam Zheng <f...@redhat.com>
> > ---
> > blockdev.c | 9 +++++++--
> > 1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/blockdev.c b/blockdev.c
> > index 52f44b2..adc0e69 100644
> > --- a/blockdev.c
> > +++ b/blockdev.c
> > @@ -1370,6 +1370,7 @@ typedef struct InternalSnapshotState {
> > BlockDriverState *bs;
> > AioContext *aio_context;
> > QEMUSnapshotInfo sn;
> > + bool created;
> > } InternalSnapshotState;
> >
> > static void internal_snapshot_prepare(BlkTransactionState *common,
> > @@ -1414,6 +1415,9 @@ static void
> > internal_snapshot_prepare(BlkTransactionState *common,
> > }
> > bs = blk_bs(blk);
> >
> > + state->bs = bs;
> > + bdrv_drained_begin(bs);
> > +
> > if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT, errp)) {
> > return;
> > }
>
> More context:
>
> /* AioContext is released in .clean() */
> state->aio_context = blk_get_aio_context(blk);
> aio_context_acquire(state->aio_context);
>
> if (!blk_is_available(blk)) {
> error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, device);
> return;
> }
> bs = blk_bs(blk);
>
> state->bs = bs;
> bdrv_drained_begin(bs);
>
> If we error out because of !blk_is_available(blk), we will still call
> bdrv_drained_end() in .clean even though bdrv_drained_begin() hasn't
> been called yet.
>
Right, if the bdrv_drained_begin() is moved down as it is in this
patch, then the state->aio_context assignment needs moved down as
well.
