Re: [PATCH 05/10] xfs_repair: force not-so-bad bmbt blocks back through the verifier

Darrick J. Wong
2015-08-17T23:48:23Z

On Mon, Aug 17, 2015 at 04:14:27PM -0500, Eric Sandeen wrote:
> On 8/14/15 8:44 PM, Darrick J. Wong wrote:
> > If during prefetch we encounter a bmbt block that fails the CRC check
> > due to corruption in the unused part of the block, force the buffer
> > back through the non-prefetch verifiers later so that the CRC is
> > updated. Otherwise, the bad checksum goes unfixed and the kernel will
> > still flag the bmbt block as invalid.
> >
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> > repair/prefetch.c | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> >
> > diff --git a/repair/prefetch.c b/repair/prefetch.c
> > index 8b261ae..fc7097f 100644
> > --- a/repair/prefetch.c
> > +++ b/repair/prefetch.c
> > @@ -276,6 +276,14 @@ pf_scan_lbtree(
> >
> > XFS_BUF_SET_PRIORITY(bp, isadir ? B_DIR_BMAP : B_BMAP);
> >
> > + /*
> > + * Make this bmbt buffer go back through the verifiers later so that
> > + * we correct checksum errors stemming from bitflips in the unused
> > + * parts of the bmbt block.
> > + */
> > + if (bp->b_error == -EFSBADCRC || bp->b_error == -EFSCORRUPTED)
> > + bp->b_flags |= LIBXFS_B_UNCHECKED;
>
> Hm, so why check EFSCORRUPTED? If you're doing what the comment says, why
> not just EFSBADCRC? EFSCORRUPTED means that in-use portions are bad, no?

You're right, I only need to hook onto EFSBADCRC. I probably got too used
to seeing checks for both everywhere. 8)

--D

>
> -Eric
>
> > +
> > rc = (*func)(XFS_BUF_TO_BLOCK(bp), level - 1, isadir, args);
> >
> > libxfs_putbuf(bp);
> >
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> > xfs@oss.sgi.com
> > http://oss.sgi.com/mailman/listinfo/xfs
> >
>
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