Re: [Qemu-devel] [PATCH v2 10/11] blockdev: Block device IO during blockdev-backup transaction

[Fam Zheng <famz@redhat.com>]

On Wed, 05/13 19:22, Wen Congyang wrote:
> On 05/14/2015 01:28 AM, Fam Zheng wrote:
> > Signed-off-by: Fam Zheng <famz@redhat.com>
> > ---
> >  blockdev.c | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/blockdev.c b/blockdev.c
> > index ae52d27..bd28183 100644
> > --- a/blockdev.c
> > +++ b/blockdev.c
> > @@ -1649,6 +1649,7 @@ typedef struct BlockdevBackupState {
> >      BlockDriverState *bs;
> >      BlockJob *job;
> >      AioContext *aio_context;
> > +    Error *blocker;
> >  } BlockdevBackupState;
> >  
> >  static void blockdev_backup_prepare(BlkTransactionState *common, Error **errp)
> > @@ -1685,6 +1686,10 @@ static void blockdev_backup_prepare(BlkTransactionState *common, Error **errp)
> >      }
> >      aio_context_acquire(state->aio_context);
> >  
> > +    state->bs = bs;
> > +    error_setg(&state->blocker, "blockdev-backup in progress");
> > +    bdrv_op_block(bs, BLOCK_OP_TYPE_DEVICE_IO, state->blocker);
> > +
> 
> Do you test this patch? You need to read from bs to do backup!!
> If the mode is none, you also need to write to bs!!

This blocker is only temporary and is removed in blockdev_backup_clean before
qmp_transaction returns.

Fam

> 
> Thanks
> Wen Congyang
> 
> >      qmp_blockdev_backup(backup->device, backup->target,
> >                          backup->sync,
> >                          backup->has_speed, backup->speed,
> > @@ -1696,7 +1701,6 @@ static void blockdev_backup_prepare(BlkTransactionState *common, Error **errp)
> >          return;
> >      }
> >  
> > -    state->bs = bs;
> >      state->job = state->bs->job;
> >  }
> >  
> > @@ -1715,6 +1719,10 @@ static void blockdev_backup_clean(BlkTransactionState *common)
> >  {
> >      BlockdevBackupState *state = DO_UPCAST(BlockdevBackupState, 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);
> >      }
> > 
>