Re: [PATCH v3] common/xfs: wipe the XFS superblock of each AGs

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Tue, Sep 24, 2019 at 06:09:19PM +0800, Zorro Lang wrote:
> xfs/030 always fails after d0e484ac699f ("check: wipe scratch devices
> between tests") get merged.
> 
> Due to xfs/030 does a sized(100m) mkfs. Before we merge above commit,
> mkfs.xfs detects an old primary superblock, it will write zeroes to
> all superblocks before formatting the new filesystem. But this won't
> be done if we wipe the first superblock(by merging above commit).
> 
> That means if we make a (smaller) sized xfs after wipefs, those *old*
> superblocks which created by last time mkfs.xfs will be left on disk.
> Then when we do xfs_repair, if xfs_repair can't find the first SB, it
> will go to find those *old* SB at first. When it finds them,
> everyting goes wrong.
> 
> So I try to wipe each XFS superblock if there's a XFS ondisk, then
> try to erase superblock of each XFS AG by default mkfs.xfs geometry.
> Thanks Darrick J. Wong helped to analyze this issue.
> 
> Reported-by: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
> Signed-off-by: Zorro Lang <zlang@redhat.com>

Looks ok to me,

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
> 
> Hi,
> 
> All changes in V3 is under:
> # Try to wipe each SB by default mkfs.xfs geometry
> ...
> ...
> 
> Thanks,
> Zorro
> 
>  common/rc  |  8 ++++++++
>  common/xfs | 40 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 48 insertions(+)
> 
> diff --git a/common/rc b/common/rc
> index 66c7fd4d..56329747 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -4045,6 +4045,14 @@ _try_wipe_scratch_devs()
>  {
>  	test -x "$WIPEFS_PROG" || return 0
>  
> +	# Do specified filesystem wipe at first
> +	case "$FSTYP" in
> +	"xfs")
> +		_try_wipe_scratch_xfs
> +		;;
> +	esac
> +
> +	# Then do wipefs on all scratch devices
>  	for dev in $SCRATCH_DEV_POOL $SCRATCH_DEV $SCRATCH_LOGDEV $SCRATCH_RTDEV; do
>  		test -b $dev && $WIPEFS_PROG -a $dev
>  	done
> diff --git a/common/xfs b/common/xfs
> index 1bce3c18..706ddf85 100644
> --- a/common/xfs
> +++ b/common/xfs
> @@ -884,3 +884,43 @@ _xfs_mount_agcount()
>  {
>  	$XFS_INFO_PROG "$1" | grep agcount= | sed -e 's/^.*agcount=\([0-9]*\),.*$/\1/g'
>  }
> +
> +# Wipe the superblock of each XFS AGs
> +_try_wipe_scratch_xfs()
> +{
> +	local num='^[0-9]+$'
> +	local agcount
> +	local agsize
> +	local dbsize
> +
> +	# Try to wipe each SB if there's an existed XFS
> +	agcount=`_scratch_xfs_get_sb_field agcount 2>/dev/null`
> +	agsize=`_scratch_xfs_get_sb_field agblocks 2>/dev/null`
> +	dbsize=`_scratch_xfs_get_sb_field blocksize 2>/dev/null`
> +	if [[ $agcount =~ $num && $agsize =~ $num && $dbsize =~ $num ]];then
> +		for ((i = 0; i < agcount; i++)); do
> +			$XFS_IO_PROG -c "pwrite $((i * dbsize * agsize)) $dbsize" \
> +				$SCRATCH_DEV >/dev/null;
> +		done
> +	fi
> +
> +	# Try to wipe each SB by default mkfs.xfs geometry
> +	local tmp=`mktemp -u`
> +	unset agcount agsize dbsize
> +	_scratch_mkfs_xfs -N 2>/dev/null | perl -ne '
> +		if (/^meta-data=.*\s+agcount=(\d+), agsize=(\d+) blks/) {
> +			print STDOUT "agcount=$1\nagsize=$2\n";
> +		}
> +		if (/^data\s+=\s+bsize=(\d+)\s/) {
> +			print STDOUT "dbsize=$1\n";
> +		}' > $tmp.mkfs
> +
> +	. $tmp.mkfs
> +	if [[ $agcount =~ $num && $agsize =~ $num && $dbsize =~ $num ]];then
> +		for ((i = 0; i < agcount; i++)); do
> +			$XFS_IO_PROG -c "pwrite $((i * dbsize * agsize)) $dbsize" \
> +				$SCRATCH_DEV >/dev/null;
> +		done
> +	fi
> +	rm -f $tmp.mkfs
> +}
> -- 
> 2.20.1
>