Re: [PATCH 01/11] xfs_scrub: separate media error reporting for attribute forks

[Eric Sandeen <sandeen@sandeen.net>]

On 9/25/19 4:36 PM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Use different functions to warn about media errors that were detected
> underlying xattr data because logical offsets for attribute fork extents
> have no meaning to users.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  scrub/phase6.c |   45 ++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 38 insertions(+), 7 deletions(-)
> 
> 
> diff --git a/scrub/phase6.c b/scrub/phase6.c
> index 4554af9a..1edd98af 100644
> --- a/scrub/phase6.c
> +++ b/scrub/phase6.c
> @@ -113,7 +113,7 @@ xfs_decode_special_owner(
>  
>  /* Report if this extent overlaps a bad region. */
>  static bool
> -xfs_report_verify_inode_bmap(
> +report_data_loss(
>  	struct scrub_ctx		*ctx,
>  	const char			*descr,
>  	int				fd,
> @@ -142,6 +142,40 @@ _("offset %llu failed read verification."), bmap->bm_offset);
>  	return true;
>  }
>  
> +/* Report if the extended attribute data overlaps a bad region. */

I'd like to see a comment above the typedef for this function
(eventually scrub_bmap_iter_fn), or above the function which uses it
(scrub_iterate_filemaps) in order to explain what the return
values mean and the implication for scanning.

Looking at this w/o a lot of context, 

"Report if the extended attribute data overlaps a bad region."

and nothing but "return true" seems ... odd.  I think what it means
is "print something if found ... and set an error for some problems,
but always continue scanning?"

> +static bool
> +report_attr_loss(
> +	struct scrub_ctx		*ctx,
> +	const char			*descr,
> +	int				fd,
> +	int				whichfork,
> +	struct fsxattr			*fsx,
> +	struct xfs_bmap			*bmap,
> +	void				*arg)
> +{
> +	struct media_verify_state	*vs = arg;
> +	struct bitmap			*bmp = vs->d_bad;
> +
> +	/* Complain about attr fork extents that don't look right. */
> +	if (bmap->bm_flags & (BMV_OF_PREALLOC | BMV_OF_DELALLOC)) {
> +		str_info(ctx, descr,
> +_("found unexpected unwritten/delalloc attr fork extent."));
> +		return true;
> +	}
> +
> +	if (fsx->fsx_xflags & FS_XFLAG_REALTIME) {
> +		str_info(ctx, descr,
> +_("found unexpected realtime attr fork extent."));
> +		return true;
> +	}

so these don't flag any error, and moveon stays true, but

> +
> +	if (bitmap_test(bmp, bmap->bm_physical, bmap->bm_length))
> +		str_error(ctx, descr,
> +_("media error in extended attribute data."));

this actually counts as an error?  OTOH report_data_loss() seems to return
false if it finds something like this, so I'm a little confused about the
difference and the behavior.  Help?

> +
> +	return true;
> +}
> +
>  /* Iterate the extent mappings of a file to report errors. */
>  static bool
>  xfs_report_verify_fd(
> @@ -155,16 +189,13 @@ xfs_report_verify_fd(
>  
>  	/* data fork */
>  	moveon = xfs_iterate_filemaps(ctx, descr, fd, XFS_DATA_FORK, &key,
> -			xfs_report_verify_inode_bmap, arg);
> +			report_data_loss, arg);
>  	if (!moveon)
>  		return false;
>  
>  	/* attr fork */
> -	moveon = xfs_iterate_filemaps(ctx, descr, fd, XFS_ATTR_FORK, &key,
> -			xfs_report_verify_inode_bmap, arg);
> -	if (!moveon)
> -		return false;
> -	return true;
> +	return xfs_iterate_filemaps(ctx, descr, fd, XFS_ATTR_FORK, &key,
> +			report_attr_loss, arg);
>  }
>  
>  /* Report read verify errors in unlinked (but still open) files. */
>