Re: [PATCH 1/2] xfs_repair: complain about ag header crc errors

[Brian Foster <bfoster@redhat.com>]

On Thu, Jun 25, 2020 at 01:52:32PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Repair doesn't complain about crc errors in the AG headers, and it
> should.  Otherwise give the admin the wrong impression about the
> state of the filesystem after a nomodify check.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  repair/scan.c |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> 
> diff --git a/repair/scan.c b/repair/scan.c
> index 505cfc53..42b299f7 100644
> --- a/repair/scan.c
> +++ b/repair/scan.c
> @@ -2441,6 +2441,8 @@ scan_ag(
>  		objname = _("root superblock");
>  		goto out_free_sb;
>  	}
> +	if (sbbuf->b_error == -EFSBADCRC)
> +		do_warn(_("superblock has bad CRC for ag %d\n"), agno);

So salvage_buffer() reads the buf and passes along the verifier. If the
verifier fails, we ignore the error and return 0 because of
LIBXFS_READBUF_SALVAGE, but leave it set in bp->b_error so it should be
accessible here. Looks Ok:

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  	libxfs_sb_from_disk(sb, sbbuf->b_addr);
>  
>  	error = salvage_buffer(mp->m_dev,
> @@ -2450,6 +2452,8 @@ scan_ag(
>  		objname = _("agf block");
>  		goto out_free_sbbuf;
>  	}
> +	if (agfbuf->b_error == -EFSBADCRC)
> +		do_warn(_("agf has bad CRC for ag %d\n"), agno);
>  	agf = agfbuf->b_addr;
>  
>  	error = salvage_buffer(mp->m_dev,
> @@ -2459,6 +2463,8 @@ scan_ag(
>  		objname = _("agi block");
>  		goto out_free_agfbuf;
>  	}
> +	if (agibuf->b_error == -EFSBADCRC)
> +		do_warn(_("agi has bad CRC for ag %d\n"), agno);
>  	agi = agibuf->b_addr;
>  
>  	/* fix up bad ag headers */
>