Re: [Qemu-devel] [PATCH 3/5] block: Simplify bdrv_reopen_abort()

[Kevin Wolf <kwolf@redhat.com>]

Am 14.08.2018 um 12:15 hat Alberto Garcia geschrieben:
> On Tue 14 Aug 2018 11:07:42 AM CEST, Kevin Wolf wrote:
> > Am 29.06.2018 um 13:37 hat Alberto Garcia geschrieben:
> >> If a bdrv_reopen_multiple() call fails, then the explicit_options
> >> QDict has to be deleted for every entry in the reopen queue. This must
> >> happen regardless of whether that entry's bdrv_reopen_prepare() call
> >> succeeded or not.
> >> 
> >> This patch simplifies the cleanup code a bit.
> >> 
> >> Signed-off-by: Alberto Garcia <berto@igalia.com>
> >> ---
> >>  block.c | 9 ++++-----
> >>  1 file changed, 4 insertions(+), 5 deletions(-)
> >> 
> >> diff --git a/block.c b/block.c
> >> index 5aaed424b9..48e8f4814c 100644
> >> --- a/block.c
> >> +++ b/block.c
> >> @@ -3060,9 +3060,10 @@ int bdrv_reopen_multiple(AioContext *ctx, BlockReopenQueue *bs_queue, Error **er
> >>  
> >>  cleanup:
> >>      QSIMPLEQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
> >> -        if (ret && bs_entry->prepared) {
> >> -            bdrv_reopen_abort(&bs_entry->state);
> >> -        } else if (ret) {
> >> +        if (ret) {
> >> +            if (bs_entry->prepared) {
> >> +                bdrv_reopen_abort(&bs_entry->state);
> >> +            }
> >>              qobject_unref(bs_entry->state.explicit_options);
> >>          }
> >>          qobject_unref(bs_entry->state.options);
> >> @@ -3351,8 +3352,6 @@ void bdrv_reopen_abort(BDRVReopenState *reopen_state)
> >>          drv->bdrv_reopen_abort(reopen_state);
> >>      }
> >>  
> >> -    qobject_unref(reopen_state->explicit_options);
> >> -
> >>      bdrv_abort_perm_update(reopen_state->bs);
> >>  }
> >
> > I think this is only correct if we make bdrv_reopen_prepare/commit/abort
> > private. At the moment they are public interfaces, so we must have
> > thought that some callers might want to integrate them into other
> > transactions.
> 
> But that's not a problem as long as the new callers unref
> state.explicit_options when bdrv_reopen_prepare() fails. They need to do
> it with state.options anyway.

Actually that makes sense because the code creating the object isn't
even in bdrv_reopen_prepare(), but in bdrv_reopen_queue_child(). So it's
the caller that owns the object and should free them too. I just
confused the two functions.

Kevin