dm mpath: return parameter error

Return a specific error message if there are an invalid number of multipath
arguments.

This invalid command returns an "Unknown error" because the ti->error field is
not set

dmsetup create --table '0 2 multipath 0 0 1 1 round-robin 0 1 1 /dev/sdh' mpath0

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 9f570b2ab7b4..230d7890ec8a 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -625,8 +625,10 @@ static struct priority_group *parse_priority_group(struct arg_set *as,
                 struct pgpath *pgpath;
                 struct arg_set path_args;
 
-                if (as->argc < nr_params)
+                if (as->argc < nr_params) {
+                        ti->error = "not enough path parameters";
                         goto bad;
+                }
 
                 path_args.argc = nr_params;
                 path_args.argv = as->argv;