kdump-lib-initramfs: Improve mount point retrieval logic

We use findmnt to find the real mount point by mount source, however,
when there is a bind mount target, findmnt will give more than one
results and what we actually want is the one without fsroot.

Will fallback to previous method if the $_mntpoint is empty.

Signed-off-by: Lichen Liu <[email protected]>

kdump-lib-initramfs.sh

@@ -103,8 +103,14 @@ get_fs_type_from_target()
 
 get_mntpoint_from_target()
 {
-	# --source is applied to ensure non-bind mount is returned
-	get_mount_info TARGET source "$1" -f
+	local _mntpoint
+	# get the first TARGET when SOURCE doesn't end with ].
+	# In most cases, a SOURCE ends with ] when fsroot or subvol exists.
+	_mntpoint=$(get_mount_info TARGET,SOURCE source "$1" | grep -v "\]$" | awk 'NR==1 { print $1 }')
+
+	# fallback to the old way when _mntpoint is empty.
+	[[ -n "$_mntpoint" ]] || _mntpoint=$(get_mount_info TARGET source "$1" -f )
+	echo $_mntpoint
 }
 
 is_ssh_dump_target()

kdump-lib.sh

@@ -205,7 +205,7 @@ get_bind_mount_source()
 
 	_fsroot=${_src#"${_src_nofsroot}"[}
 	_fsroot=${_fsroot%]}
-	_mnt=$(get_mount_info TARGET source "$_src_nofsroot" -f)
+	_mnt=$(get_mntpoint_from_target "$_src_nofsroot")
 
 	# for btrfs, _fsroot will also contain the subvol value as well, strip it
 	if [[ $_fstype == btrfs ]]; then