Re: [PATCH 2/2] xfs_admin: enable online label getting and setting

[Carlos Maiolino <cmaiolino@redhat.com>]

On Mon, Dec 02, 2019 at 06:47:55PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Connect xfs_admin -L to the xfs_io label command so that we can get and
> set the label for a live filesystem.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  db/xfs_admin.sh      |   42 ++++++++++++++++++++++++++++++++++++++++--
>  man/man8/xfs_admin.8 |    4 +++-
>  2 files changed, 43 insertions(+), 3 deletions(-)
> 

Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>

> 
> diff --git a/db/xfs_admin.sh b/db/xfs_admin.sh
> index bd325da2..d18959bf 100755
> --- a/db/xfs_admin.sh
> +++ b/db/xfs_admin.sh
> @@ -7,8 +7,30 @@
>  status=0
>  DB_OPTS=""
>  REPAIR_OPTS=""
> +IO_OPTS=""
>  USAGE="Usage: xfs_admin [-efjlpuV] [-c 0|1] [-L label] [-U uuid] device [logdev]"
>  
> +# Try to find a loop device associated with a file.  We only want to return
> +# one loopdev (multiple loop devices can attach to a single file) so we grab
> +# the last line and return it if it's actually a block device.
> +try_find_loop_dev_for_file() {
> +	local x="$(losetup -O NAME -j "$1" 2> /dev/null | tail -n 1)"
> +	test -b "$x" && echo "$x"
> +}
> +
> +# See if we can find a mount point for the argument.
> +find_mntpt_for_arg() {
> +	local arg="$1"
> +
> +	# See if we can map the arg to a loop device
> +	local loopdev="$(try_find_loop_dev_for_file "${arg}")"
> +	test -n "$loopdev" && arg="$loopdev"
> +
> +	# If we find a mountpoint for the device, do a live query;
> +	# otherwise try reading the fs with xfs_db.
> +	findmnt -t xfs -f -n -o TARGET "${arg}" 2> /dev/null
> +}
> +
>  while getopts "efjlpuc:L:U:V" c
>  do
>  	case $c in
> @@ -16,8 +38,16 @@ do
>  	e)	DB_OPTS=$DB_OPTS" -c 'version extflg'";;
>  	f)	DB_OPTS=$DB_OPTS" -f";;
>  	j)	DB_OPTS=$DB_OPTS" -c 'version log2'";;
> -	l)	DB_OPTS=$DB_OPTS" -r -c label";;
> -	L)	DB_OPTS=$DB_OPTS" -c 'label "$OPTARG"'";;
> +	l)	DB_OPTS=$DB_OPTS" -r -c label"
> +		IO_OPTS=$IO_OPTS" -r -c label"
> +		;;
> +	L)	DB_OPTS=$DB_OPTS" -c 'label "$OPTARG"'"
> +		if [ "$OPTARG" = "--" ]; then
> +			IO_OPTS=$IO_OPTS" -c 'label -c'"
> +		else
> +			IO_OPTS=$IO_OPTS" -c 'label -s "$OPTARG"'"
> +		fi
> +		;;
>  	p)	DB_OPTS=$DB_OPTS" -c 'version projid32bit'";;
>  	u)	DB_OPTS=$DB_OPTS" -r -c uuid";;
>  	U)	DB_OPTS=$DB_OPTS" -c 'uuid "$OPTARG"'";;
> @@ -41,6 +71,14 @@ case $# in
>  				REPAIR_OPTS=$REPAIR_OPTS" -l '$2'"
>  		fi
>  
> +		# Try making the changes online, if supported
> +		if [ -n "$IO_OPTS" ] && mntpt="$(find_mntpt_for_arg "$1")"
> +		then
> +			eval xfs_io -x -p xfs_admin $IO_OPTS "$mntpt"
> +			test "$?" -eq 0 && exit 0
> +		fi
> +
> +		# Otherwise try offline changing
>  		if [ -n "$DB_OPTS" ]
>  		then
>  			eval xfs_db -x -p xfs_admin $DB_OPTS $1
> diff --git a/man/man8/xfs_admin.8 b/man/man8/xfs_admin.8
> index 8afc873f..220dd803 100644
> --- a/man/man8/xfs_admin.8
> +++ b/man/man8/xfs_admin.8
> @@ -26,7 +26,7 @@ uses the
>  .BR xfs_db (8)
>  command to modify various parameters of a filesystem.
>  .PP
> -Devices that are mounted cannot be modified.
> +Devices that are mounted cannot be modified, except as noted below.
>  Administrators must unmount filesystems before
>  .BR xfs_admin " or " xfs_db (8)
>  can convert parameters.
> @@ -67,6 +67,7 @@ log buffers).
>  .TP
>  .B \-l
>  Print the current filesystem label.
> +This command can be run if the filesystem is mounted.
>  .TP
>  .B \-p
>  Enable 32bit project identifier support (PROJID32BIT feature).
> @@ -102,6 +103,7 @@ The filesystem label can be cleared using the special "\c
>  .B \-\-\c
>  " value for
>  .IR label .
> +This command can be run if the filesystem is mounted.
>  .TP
>  .BI \-U " uuid"
>  Set the UUID of the filesystem to
> 

-- 
Carlos