From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-xfs-owner@vger.kernel.org>
Received: from mx1.redhat.com ([209.132.183.28]:44844 "EHLO mx1.redhat.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1726260AbfDVT1P (ORCPT <rfc822;linux-xfs@vger.kernel.org>);
        Mon, 22 Apr 2019 15:27:15 -0400
Date: Mon, 22 Apr 2019 14:27:11 -0500
From: Bill O'Donnell <billodo@redhat.com>
Subject: Re: [PATCH 02/10] xfs_info: use findmnt to handle mounted block
 devices
Message-ID: <20190422192711.GA29660@redhat.com>
References: <155594788997.115924.16224143537288136652.stgit@magnolia>
 <155594790268.115924.87682432738525436.stgit@magnolia>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <155594790268.115924.87682432738525436.stgit@magnolia>
Sender: linux-xfs-owner@vger.kernel.org
List-ID: <linux-xfs.vger.kernel.org>
List-Id: xfs
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: sandeen@sandeen.net, linux-xfs@vger.kernel.org

On Mon, Apr 22, 2019 at 08:45:02AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Use findmnt to determine if the passed-in argument is associated with a
> mount point, and if so, use spaceman to query the mounted filesystem.
> If the user passed in a file, try to find out if it's a loop mounted
> live filesystem and if so query the live filesystem.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

Reviewed-by: Bill O'Donnell <billodo@redhat.com>

> ---
>  debian/control       |    2 +-
>  spaceman/xfs_info.sh |   22 +++++++++++++++++++---
>  2 files changed, 20 insertions(+), 4 deletions(-)
> 
> 
> diff --git a/debian/control b/debian/control
> index f4f807b0..0b3205f5 100644
> --- a/debian/control
> +++ b/debian/control
> @@ -8,7 +8,7 @@ Standards-Version: 4.0.0
>  Homepage: https://xfs.wiki.kernel.org/
>  
>  Package: xfsprogs
> -Depends: ${shlibs:Depends}, ${misc:Depends}, python3:any
> +Depends: ${shlibs:Depends}, ${misc:Depends}, python3:any, util-linux
>  Provides: fsck-backend
>  Suggests: xfsdump, acl, attr, quota
>  Breaks: xfsdump (<< 3.0.0)
> diff --git a/spaceman/xfs_info.sh b/spaceman/xfs_info.sh
> index ecf17f61..1bf6d2c3 100755
> --- a/spaceman/xfs_info.sh
> +++ b/spaceman/xfs_info.sh
> @@ -7,6 +7,14 @@
>  OPTS=""
>  USAGE="Usage: xfs_info [-V] [-t mtab] [mountpoint|device|file]"
>  
> +# Try to find a loop device associated with a file.  We only want to return
> +# one loopdev (multiple loop devices can attach to a single file) so we grab
> +# the last line and return it if it's actually a block device.
> +try_find_loop_dev_for_file() {
> +	local x="$(losetup -O NAME -j "$1" 2> /dev/null | tail -n 1)"
> +	test -b "$x" && echo "$x"
> +}
> +
>  while getopts "t:V" c
>  do
>  	case $c in
> @@ -24,11 +32,19 @@ set -- extra "$@"
>  shift $OPTIND
>  case $# in
>  	1)
> -		if [ -b "$1" ] || [ -f "$1" ]; then
> -			xfs_db -p xfs_info -c "info" $OPTS "$1"
> +		arg="$1"
> +
> +		# See if we can map the arg to a loop device
> +		loopdev="$(try_find_loop_dev_for_file "${arg}")"
> +		test -n "${loopdev}" && arg="${loopdev}"
> +
> +		# If we find a mountpoint for the device, do a live query;
> +		# otherwise try reading the fs with xfs_db.
> +		if mountpt="$(findmnt -f -n -o TARGET "${arg}" 2> /dev/null)"; then
> +			xfs_spaceman -p xfs_info -c "info" $OPTS "${mountpt}"
>  			status=$?
>  		else
> -			xfs_spaceman -p xfs_info -c "info" $OPTS "$1"
> +			xfs_db -p xfs_info -c "info" $OPTS "${arg}"
>  			status=$?
>  		fi
>  		;;
>