Return error in case of invalid 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 Signed-off-by: Alasdair G Kergon --- drivers/md/dm-mpath.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletion(-) Index: linux-2.6.26-rc8/drivers/md/dm-mpath.c =================================================================== --- linux-2.6.26-rc8.orig/drivers/md/dm-mpath.c 2008-06-30 11:13:44.000000000 +0100 +++ linux-2.6.26-rc8/drivers/md/dm-mpath.c 2008-06-30 11:13:55.000000000 +0100 @@ -630,8 +630,10 @@ static struct priority_group *parse_prio 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;