On Mon, Apr 20, 2020 at 01:53:22PM +1000, Dave Chinner wrote:
> On Fri, Apr 17, 2020 at 11:08:53AM -0400, Brian Foster wrote:
> > The dquot read/write verifier calls xfs_dqblk_verify() on every
> > dquot in the buffer. Remove the duplicate call from
> > xfs_qm_dqflush().
>
> Ah, I think there's a bug here - it's not supposed to be a
> duplicate....
>
> > Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
> > ---
> > fs/xfs/xfs_dquot.c | 14 --------------
> > 1 file changed, 14 deletions(-)
> >
> > diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
> > index af2c8e5ceea0..73032c18a94a 100644
> > --- a/fs/xfs/xfs_dquot.c
> > +++ b/fs/xfs/xfs_dquot.c
> > @@ -1071,7 +1071,6 @@ xfs_qm_dqflush(
> > struct xfs_buf *bp;
> > struct xfs_dqblk *dqb;
> > struct xfs_disk_dquot *ddqp;
> > - xfs_failaddr_t fa;
> > int error;
> >
> > ASSERT(XFS_DQ_IS_LOCKED(dqp));
> > @@ -1116,19 +1115,6 @@ xfs_qm_dqflush(
> > dqb = bp->b_addr + dqp->q_bufoffset;
> > ddqp = &dqb->dd_diskdq;
> >
> > - /*
> > - * A simple sanity check in case we got a corrupted dquot.
> > - */
> > - fa = xfs_dqblk_verify(mp, dqb, be32_to_cpu(ddqp->d_id), 0);
>
> So this verifies the on disk dquot ....
>
> > - if (fa) {
> > - xfs_alert(mp, "corrupt dquot ID 0x%x in memory at %pS",
>
> ...which issues an "in memory corruption" alert on failure...
>
> > - be32_to_cpu(ddqp->d_id), fa);
> > - xfs_buf_relse(bp);
> > - xfs_dqfunlock(dqp);
> > - xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
> > - return -EFSCORRUPTED;
> > - }
> > -
> > /* This is the only portion of data that needs to persist */
> > memcpy(ddqp, &dqp->q_core, sizeof(struct xfs_disk_dquot));
>
> .... and on success we immediately overwrite the on-disk copy with
> the unchecked in-memory copy of the dquot.
>
> IOWs, I think that verification call here should be checking the
> in-memory dquot core, not the on disk buffer that is about to get
> trashed. i.e. something like this:
>
> - fa = xfs_dqblk_verify(mp, dqb, be32_to_cpu(ddqp->d_id), 0);
> + fa = xfs_dquot_verify(mp, &dqp->q_core, be32_to_cpu(ddqp->d_id), 0);
>
Isn't this still essentially duplicated by the write verifier? I don't
feel strongly about changing it as above vs. removing it, but it does
still seem unnecessary to me..
Brian
> Cheers,
>
> Dave.
> --
> Dave Chinner
> david@xxxxxxxxxxxxx
>
