Re: [PATCH v3 2/2] xfs_admin: get UUID of mounted filesystem

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

On Wed, Jan 04, 2023 at 04:36:13PM -0800, Catherine Hoang wrote:
> Adapt this tool to call xfs_io to retrieve the UUID of a mounted filesystem.
> This is a precursor to enabling xfs_admin to set the UUID of a mounted
> filesystem.
> 
> Signed-off-by: Catherine Hoang <catherine.hoang@oracle.com>
> ---
>  db/xfs_admin.sh | 61 +++++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 51 insertions(+), 10 deletions(-)
> 
> diff --git a/db/xfs_admin.sh b/db/xfs_admin.sh
> index 409975b2..b73fb3ad 100755
> --- a/db/xfs_admin.sh
> +++ b/db/xfs_admin.sh
> @@ -5,8 +5,11 @@
>  #
>  
>  status=0
> +require_offline=""
> +require_online=""
>  DB_OPTS=""
>  REPAIR_OPTS=""
> +IO_OPTS=""
>  REPAIR_DEV_OPTS=""
>  LOG_OPTS=""
>  USAGE="Usage: xfs_admin [-efjlpuV] [-c 0|1] [-L label] [-O v5_feature] [-r rtdev] [-U uuid] device [logdev]"
> @@ -14,17 +17,37 @@ USAGE="Usage: xfs_admin [-efjlpuV] [-c 0|1] [-L label] [-O v5_feature] [-r rtdev
>  while getopts "c:efjlL:O:pr:uU:V" c
>  do
>  	case $c in
> -	c)	REPAIR_OPTS=$REPAIR_OPTS" -c lazycount="$OPTARG;;
> -	e)	DB_OPTS=$DB_OPTS" -c 'version extflg'";;
> -	f)	DB_OPTS=$DB_OPTS" -f";;
> -	j)	DB_OPTS=$DB_OPTS" -c 'version log2'";;
> +	c)	REPAIR_OPTS=$REPAIR_OPTS" -c lazycount="$OPTARG
> +		require_offline=1
> +		;;
> +	e)	DB_OPTS=$DB_OPTS" -c 'version extflg'"
> +		require_offline=1
> +		;;
> +	f)	DB_OPTS=$DB_OPTS" -f"
> +		require_offline=1
> +		;;
> +	j)	DB_OPTS=$DB_OPTS" -c 'version log2'"
> +		require_offline=1
> +		;;
>  	l)	DB_OPTS=$DB_OPTS" -r -c label";;

Now that xfs_admin can issue commands directly against mounted
filesystems, I suppose it ought to wire up support for querying and
changing the label as well.  Doing that should be trivial, and
definitely an idea for a separate patch:

# xfs_io -c 'label' /mnt
label = "hi"
# xfs_io -c 'label -s bye' /mnt
label = "bye"
# xfs_io -c 'label' /mnt
label = "bye"

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

--D

> -	L)	DB_OPTS=$DB_OPTS" -c 'label "$OPTARG"'";;
> -	O)	REPAIR_OPTS=$REPAIR_OPTS" -c $OPTARG";;
> -	p)	DB_OPTS=$DB_OPTS" -c 'version projid32bit'";;
> -	r)	REPAIR_DEV_OPTS=" -r '$OPTARG'";;
> -	u)	DB_OPTS=$DB_OPTS" -r -c uuid";;
> -	U)	DB_OPTS=$DB_OPTS" -c 'uuid "$OPTARG"'";;
> +	L)	DB_OPTS=$DB_OPTS" -c 'label "$OPTARG"'"
> +		require_offline=1
> +		;;
> +	O)	REPAIR_OPTS=$REPAIR_OPTS" -c $OPTARG"
> +		require_offline=1
> +		;;
> +	p)	DB_OPTS=$DB_OPTS" -c 'version projid32bit'"
> +		require_offline=1
> +		;;
> +	r)	REPAIR_DEV_OPTS=" -r '$OPTARG'"
> +		require_offline=1
> +		;;
> +	u)	DB_OPTS=$DB_OPTS" -r -c uuid"
> +		IO_OPTS=$IO_OPTS" -r -c fsuuid"
> +		;;
> +	U)	DB_OPTS=$DB_OPTS" -c 'uuid "$OPTARG"'"
> +		require_offline=1
> +		;;
>  	V)	xfs_db -p xfs_admin -V
>  		status=$?
>  		exit $status
> @@ -38,6 +61,24 @@ set -- extra $@
>  shift $OPTIND
>  case $# in
>  	1|2)
> +		if mntpt="$(findmnt -t xfs -f -n -o TARGET "$1" 2>/dev/null)"; then
> +			# filesystem is mounted
> +			if [ -n "$require_offline" ]; then
> +				echo "$1: filesystem is mounted."
> +				exit 2
> +			fi
> +
> +			if [ -n "$IO_OPTS" ]; then
> +				exec xfs_io -p xfs_admin $IO_OPTS "$mntpt"
> +			fi
> +		fi
> +
> +		# filesystem is not mounted
> +		if [ -n "$require_online" ]; then
> +			echo "$1: filesystem is not mounted"
> +			exit 2
> +		fi
> +
>  		# Pick up the log device, if present
>  		if [ -n "$2" ]; then
>  			LOG_OPTS=" -l '$2'"
> -- 
> 2.25.1
>