Add a is_mounted helper

Use is_mounted helper instaed of calling findmnt directly or checking if
"mount" value is empty.

If findmnt looks for fstab as well, some non mounted entry will also
return value. Required to support non-mounted target.

Signed-off-by: Kairui Song <kasong@redhat.com>
Acked-by: Pingfan Liu <piliu@redhat.com>

kdump-lib-initramfs.sh

@@ -101,7 +101,7 @@ dump_fs()
     local _mp=$(findmnt -k -f -n -r -o TARGET $1)
     local _op=$(findmnt -k -f -n -r -o OPTIONS $1)
 
-    if [ -z "$_mp" ]; then
+    if ! is_mounted "$_mp"; then
         _dev=$(findmnt -s -f -n -r -o SOURCE $1)
         _mp=$(findmnt -s -f -n -r -o TARGET $1)
         _op=$(findmnt -s -f -n -r -o OPTIONS $1)

kdump-lib.sh

@@ -246,6 +246,11 @@ get_target_from_path()
     echo $_target
 }
 
+is_mounted()
+{
+    findmnt -k -n $1 &>/dev/null
+}
+
 get_fs_type_from_target()
 {
     findmnt -k -f -n -r -o FSTYPE $1

kdumpctl

@@ -475,7 +475,7 @@ check_dump_fs_modified()
 		fi
 	fi
 
-	if ! findmnt $_target >/dev/null; then
+	if ! is_mounted $_target; then
 		echo "Dump target $_target is probably not mounted."
 		return 2
 	fi

mkdumprd

@@ -366,7 +366,7 @@ do
         extra_modules="$extra_modules $config_val"
         ;;
     ext[234]|xfs|btrfs|minix|nfs)
-        if ! findmnt $config_val >/dev/null; then
+        if ! is_mounted $config_val; then
             perror_exit "Dump target $config_val is probably not mounted."
         fi