Re: [Qemu-block] [PATCH] blockdev: Unset temporary flag when changing medium.

[Alyssa Milburn]

On Sat, Feb 06, 2016 at 02:04:23PM +0100, Max Reitz wrote:
> On 04.02.2016 18:36, Alyssa Milburn wrote:
> > This avoids a 'change' command from the monitor unlink()ing the new
> > file if the bdrv was previously snapshotted.
> > 
> > Signed-off-by: Alyssa Milburn <address@hidden>
> > ---
> >  blockdev.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/blockdev.c b/blockdev.c
> > index be4ca44..d39c2e6 100644
> > --- a/blockdev.c
> > +++ b/blockdev.c
> > @@ -2514,6 +2514,7 @@ void qmp_blockdev_change_medium(const char *device, 
> > const char *filename,
> >      }
> >  
> >      bdrv_flags = blk_get_open_flags_from_root_state(blk);
> > +    bdrv_flags &= ~BDRV_O_TEMPORARY;
> >  
> >      if (!has_read_only) {
> >          read_only = BLOCKDEV_CHANGE_READ_ONLY_MODE_RETAIN;
> > 
> 
> This patch is correct (thanks!), but I think we want to unset even more
> flags, namely BDRV_O_SNAPSHOT, BDRV_O_NO_BACKING, and BDRV_O_PROTOCOL.

Thanks. I posted an updated patch with this change (but of course, this is a
trivial patch anyway). It's not entirely clear to me which flags should(n't)
be preserved and where to do that. Since the snapshotted file is part of a
chain (and the original flags are "correct") I wondered if this might not be
the ideal fix, but it seems safe/sane to do it here.

- Alyssa