[PATCH 5/9] repair: detect CRC errors in AG headers

[Christoph Hellwig]

On Tue, Apr 15, 2014 at 06:24:57PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner at redhat.com>
> 
> repair doesn't currently detect verifier errors in AG header
> blocks - apart from the primary superblock they are not detected.
> They are, fortunately, corrected in the important cases (AGF, AGI
> and AGFL) because these structures are rebuilt in phase 5, but if
> you run xfs_repair in checking mode it won't report them as bad.

Shouldn't we apply the same scheme as for directories here, that is if
it fails with a verifier error re-read without the verifier and then
still do the full check as well?

Btw, it might make sense to have special read_buf variants in libxfs
that always return a valid buffer even if the verifier fails, just
telling us about it without having to re-read.