On Thu, Sep 24, 2020 at 06:40:41AM +0100, Christoph Hellwig wrote:
> On Wed, Sep 23, 2020 at 11:24:37AM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> >
> > Actually take the rt lock before updating the bitmap from multiple
> > threads. This fixes an infrequent corruption problem when running
> > generic/013 and rtinherit=1 is set on the root dir.
> >
> > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> > ---
> > repair/dinode.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/repair/dinode.c b/repair/dinode.c
> > index 57013bf149b2..07f3f83aef8c 100644
> > --- a/repair/dinode.c
> > +++ b/repair/dinode.c
> > @@ -184,6 +184,7 @@ process_rt_rec(
> > xfs_rfsblock_t *tot,
> > int check_dups)
> > {
> > + struct aglock *lock = &ag_locks[(signed)NULLAGNUMBER];
>
> Err, what is this weird cast doing here?
Well.... ag_locks is allocated with length ag_locks[agcount + 1], and
then the pointer is incremented so that ag_locks[-1] is the rt lock.
NULLAGNUMBER is cast to xfs_agnumber_t, which is uint32_t, so we have to
cast it back to signed so that we actually do the pointer subtraction(!)
Yeah, I know, it's nuts...
--D
> The rest looks sane.
