Re: [PATCH] xfs/191: fix xattr leaf block emptying on 64k blocksized fses

["Darrick J. Wong" <djwong@kernel.org>]

On Thu, Feb 02, 2023 at 10:09:40PM +0100, Anthony Iliopoulos wrote:
> This test is failing on filesystems with 64k blocksize since the leaf
> hdr.firstused field is 16 bit and as such trying to reset it to $dbsize
> overflows and is rejected by xfs_db. The leaf is never properly resetted
> and the discrepancy is picked up by xfs_repair, thus failing the test.
> 
> Fix it by setting it to XFS_ATTR3_LEAF_NULLOFF (0) as this is the proper
> on-disk value to indicate an empty leaf on 64k blocksized fses.
> 
> Signed-off-by: Anthony Iliopoulos <ailiop@suse.com>
> ---
>  tests/xfs/191 | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/xfs/191 b/tests/xfs/191
> index 4f0a9b9eeef5..8dd875fcd28b 100755
> --- a/tests/xfs/191
> +++ b/tests/xfs/191
> @@ -78,10 +78,20 @@ make_empty_leaf() {
>  
>  	base=$(_scratch_xfs_get_metadata_field "hdr.freemap[0].base" "inode $inum" "ablock 0")
>  
> +	# 64k dbsize is a special case since it overflows the 16 bit firstused
> +	# field and it needs to be set to the special XFS_ATTR3_LEAF_NULLOFF (0)
> +	# value to indicate a null leaf. For more details see kernel commit:
> +	# e87021a2bc10 ("xfs: use larger in-core attr firstused field and detect overflow").

Do we need a second _fixed_by_kernel_commit here?

> +	if [ $dbsize -eq 65536 ]; then
> +		firstused=0;
> +	else
> +		firstused=$dbsize;

Trailing semicolon not necessary here.

> +	fi

Otherwise, looks correct to me, so
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> +
>  	_scratch_xfs_db -x -c "inode $inum" -c "ablock 0" \
>  		-c "write -d hdr.count 0" \
>  		-c "write -d hdr.usedbytes 0" \
> -		-c "write -d hdr.firstused $dbsize" \
> +		-c "write -d hdr.firstused $firstused" \
>  		-c "write -d hdr.freemap[0].size $((dbsize - base))" \
>  		-c print >> $seqres.full
>  }
> -- 
> 2.35.3
>