Re: [PATCH 03/10] xfs_repair: ignore "repaired" flag after we decide to clear xattr block

Darrick J. Wong
2015-08-17T20:50:31Z

On Mon, Aug 17, 2015 at 02:20:32PM -0500, Eric Sandeen wrote:
> On 8/14/15 8:43 PM, Darrick J. Wong wrote:
> > If in the course of examining extended attribute block contents we
> > first decide to repair an entry (*repair = 1) but secondly decide to
> > clear the whole block, set *repair = 0 because the clearing action
> > only happens if *repair == 0. Put another way, if we're nuking a
> > block, don't pretend like we've fixed it too.
>
> Hm, or what happens otherwise?
>
> TBH this is making my brain hurt, chasing it all the way back up
> the callchain. It's *repair not *repaired; it's not saying we
> fixed it, but that we should fix it, right? It'll take me a while
> to work out what all the callers do with the "clearit" return from
> process_attr_leaf_block and with *repair.

I thought *repair actually did mean *repaired (past tense). But I might just
be confused? xfs_attr.c:939 says:

do_warn(
_("removing attribute entry %d for inode %" PRIu64 "\n"),
i, ino);
tempentry = (xfs_attr_sf_entry_t *)
((intptr_t) currententry +
XFS_ATTR_SF_ENTSIZE(currententry));
memmove(currententry,tempentry,remainingspace);
asf->hdr.count -= 1;
i--; /* no worries, it will wrap back to 0 */
*repair = 1;

...that looks like a repair to me? Also see attr_repair.c:965:

if (asf->hdr.count != i) {
if (no_modify) {
do_warn(
_("would have corrected attribute entry count in inode %" PRIu64 " from %d to %d\n"),
ino, asf->hdr.count, i);
} else {
do_warn(
_("corrected attribute entry count in inode %" PRIu64 ", was %d, now %d\n"),
ino, asf->hdr.count, i);
asf->hdr.count = i;
*repair = 1;
}
}

...looks like we fix asf->hdr.count and then set *repair to 1.

> Did you have a specific example of something going wrong?

A few dozen runs of xfs/72[0-2] are pretty good at hitting this.

--D

>
> thanks,
> -Eric
>
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> > repair/attr_repair.c | 14 +++++++++++++-
> > 1 file changed, 13 insertions(+), 1 deletion(-)
> >
> >
> > diff --git a/repair/attr_repair.c b/repair/attr_repair.c
> > index 62f80e7..2bd9334 100644
> > --- a/repair/attr_repair.c
> > +++ b/repair/attr_repair.c
> > @@ -1311,6 +1311,13 @@ process_leaf_attr_block(
> > * we can add it then.
> > */
> > }
> > + /*
> > + * If we're just going to zap the block, don't pretend like we
> > + * repaired it, because repairing the block stops the clear
> > + * operation.
> > + */
> > + if (clearit)
> > + *repair = 0;
> > if (*repair)
> > xfs_attr3_leaf_hdr_to_disk(mp->m_attr_geo, leaf, &leafhdr);
> >
> > @@ -1524,6 +1531,7 @@ process_longform_attr(
> > xfs_dahash_t next_hashval;
> > int repairlinks = 0;
> > struct xfs_attr3_icleaf_hdr leafhdr;
> > + int error;
> >
> > *repair = 0;
> >
> > @@ -1604,12 +1612,16 @@ process_longform_attr(
> > libxfs_writebuf(bp, 0);
> > } else
> > libxfs_putbuf(bp);
> > - return (process_node_attr(mp, ino, dip, blkmap)); /* + repair */
> > + error = process_node_attr(mp, ino, dip, blkmap); /* + repair */
> > + if (error)
> > + *repair = 0;
> > + return error;
> > default:
> > do_warn(
> > _("bad attribute leaf magic # %#x for dir ino %" PRIu64 "\n"),
> > be16_to_cpu(leaf->hdr.info.magic), ino);
> > libxfs_putbuf(bp);
> > + *repair = 0;
> > return(1);
> > }
> >
> >
> > _______________________________________________
> > xfs mailing list
> > xfs@oss.sgi.com
> > http://oss.sgi.com/mailman/listinfo/xfs
> >
>
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