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

[Eric Sandeen <sandeen@sandeen.net>]

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?

-Eric

> +
>  	rc = (*func)(XFS_BUF_TO_BLOCK(bp), level - 1, isadir, args);
>  
>  	libxfs_putbuf(bp);
> 
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