The Tuesday 11 Feb 2014 à 16:12:17 (+0800), Fam Zheng wrote :
> On Mon, 02/10 22:49, Benoît Canet wrote:
> > Take into account the fact that a block filter like quorum will be in
> > bs->file
> > while a regular block driver device is really on the top level.
> >
> > Signed-off-by: Benoit Canet <ben...@irqsave.net>
> > ---
> > block.c | 14 ++++++++------
> > 1 file changed, 8 insertions(+), 6 deletions(-)
> >
> > diff --git a/block.c b/block.c
> > index 07ac50a..d04f535 100644
> > --- a/block.c
> > +++ b/block.c
> > @@ -5400,14 +5400,16 @@ bool bdrv_is_first_non_filter(BlockDriverState
> > *candidate)
> >
> > /* walk down the bs forest recursively */
> > QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
> > - bool perm;
> > -
> > - if (!bs->file) {
> > - continue;
> > + bool perm = false;
> > +
> > + if (bs->file &&
> > + bs->file->drv &&
> > + bs->file->drv->authorizations[BS_IS_A_FILTER]) {
> > + perm = bdrv_recurse_is_first_non_filter(bs->file, candidate);
> > + } else if (bs == candidate) {
> > + perm = true;
> > }
> >
> > - perm = bdrv_recurse_is_first_non_filter(bs->file, candidate);
> > -
> > /* candidate is the first non filter */
> > if (perm) {
> > return true;
>
> With this change, if the top level driver has ->file, its implementation of
> .bdrv_recurse_is_first_non_filter() is skipped and bs->file is the start
> point.
>
> So we have an implication that single child block drivers (that has ->file)
> doesn't need to, and shouldn't implement this operation, as commentted above
> bdrv_generic_is_first_non_filter.
>
> Tested that this patch fixes the external snapshot problem, but didn't test
> the "quorum as bs->file case".
>
> Thanks,
>
> Reviewed-by: Fam Zheng <f...@redhat.com>
After extensive testing of all type of quorum instanciations and snapshots I
discovered that we are not done yet with this issue.
When instantiating quorum from the command line the quorum driver is in
bs->file->drv.
When using QMP's blockdev_add at once or by using references the quorum driver
is in bs->drv.
As a result this patch work in half the cases: regular file and command line
quorum but not when quorum is instantiated via QMP.
I don't understand why the block layer have this irregular behavior regarding
quorum instantiation.
What would be the best way to fix this ?
Best regards
Benoît
