Re: [Qemu-devel] [PATCH v4 7/7] block: Allow backup on referenced named BlockDriverState

[Kevin Wolf <kwolf@redhat.com>]

Am 26.11.2013 um 04:06 hat Fam Zheng geschrieben:
> On 2013年11月25日 19:23, Kevin Wolf wrote:
> >Am 22.11.2013 um 06:24 hat Fam Zheng geschrieben:
> >>Drive backup is a read only operation on source bs. We want to allow
> >>this specific case to enable image-fleecing. Note that when
> >>image-fleecing job starts, the job still add its blocker to source bs,
> >>and any other operation on it will be blocked by that.
> >>
> >>Signed-off-by: Fam Zheng <famz@redhat.com>
> >>---
> >>  block.c | 2 ++
> >>  1 file changed, 2 insertions(+)
> >>
> >>diff --git a/block.c b/block.c
> >>index a5da656..d30be51 100644
> >>--- a/block.c
> >>+++ b/block.c
> >>@@ -1179,6 +1179,8 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
> >>                             "device is used as backing hd of '%s'",
> >>                             bs->device_name);
> >>                  bdrv_op_block_all(bs->backing_hd, bs->backing_blocker);
> >>+                bdrv_op_unblock(bs->backing_hd, BLOCK_OP_TYPE_BACKUP,
> >>+                                bs->backing_blocker);
> >>                  pstrcpy(bs->backing_file, sizeof(bs->backing_file),
> >>                          bs->backing_hd->filename);
> >>                  pstrcpy(bs->backing_format, sizeof(bs->backing_format),
> >
> >We probably need separate blockers for "can be a backup source" and "can
> >be a backup target". Because I think this allows using it as a
> >read-write target as well, which was not intended.
> >
> 
> Yes. Will do it.
> 
> >Do we need to cover this in other parts of the code as well, like when
> >adding a new BDS during external snapshot creation?
> >
> 
> Does it have a name? If not I think we are safe there.

Not yet, but I think it won't be long until we do have named nodes
created this way, so considering it now certainly can't hurt.

Kevin