Re: [PATCH 2/6] xfs_repair: clear DIFLAG2_NREXT64 when filesystem doesn't support nrext64

[Dave Chinner <david@fromorbit.com>]

On Tue, Jun 28, 2022 at 01:49:25PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> Clear the nrext64 inode flag if the filesystem doesn't have the nrext64
> feature enabled in the superblock.
> 
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---
>  repair/dinode.c |   19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> 
> diff --git a/repair/dinode.c b/repair/dinode.c
> index 00de31fb..547c5833 100644
> --- a/repair/dinode.c
> +++ b/repair/dinode.c
> @@ -2690,6 +2690,25 @@ _("bad (negative) size %" PRId64 " on inode %" PRIu64 "\n"),
>  			}
>  		}
>  
> +		if (xfs_dinode_has_large_extent_counts(dino) &&
> +		    !xfs_has_large_extent_counts(mp)) {
> +			if (!uncertain) {
> +				do_warn(
> +	_("inode %" PRIu64 " is marked large extent counts but file system does not support large extent counts\n"),
> +					lino);
> +			}
> +			flags2 &= ~XFS_DIFLAG2_NREXT64;
> +
> +			if (no_modify) {
> +				do_warn(_("would zero extent counts.\n"));
> +			} else {
> +				do_warn(_("zeroing extent counts.\n"));
> +				dino->di_nextents = 0;
> +				dino->di_anextents = 0;
> +				*dirty = 1;

Is that necessary? If the existing extent counts are within the
bounds of the old extent fields, then shouldn't we just rewrite the
current values into the old format rather than trashing all the
data/xattrs on the inode?

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com