Allow to specify only one disk. This is helpful when we want to extend

our concatenated device later.

MFC after:	1 week

2 files changed, 16 insertions, 5 deletions

diff --git a/sbin/geom/class/concat/gconcat.8 b/sbin/geom/class/concat/gconcat.8
index c91c0b9..2e1b79d 100644
--- a/sbin/geom/class/concat/gconcat.8
+++ b/sbin/geom/class/concat/gconcat.8
@@ -35,7 +35,7 @@
 .Cm create
 .Op Fl v
 .Ar name
-.Ar prov prov ...
+.Ar prov ...
 .Nm
 .Cm destroy
 .Op Fl fv
@@ -44,7 +44,7 @@
 .Cm label
 .Op Fl hv
 .Ar name
-.Ar prov prov ...
+.Ar prov ...
 .Nm
 .Cm stop
 .Op Fl fv
@@ -168,10 +168,21 @@ umount /mnt
 gconcat stop data
 gconcat unload
 .Ed
+.Pp
+Configure concatenated provider on one disk only.
+Create file system.
+Add two more disks and extend existing file system.
+.Bd -literal -offset indent
+gconcat label data /dev/da0
+newfs /dev/concat/data
+gconcat label data /dev/da0 /dev/da1 /dev/da2
+growfs /dev/concat/data
+.Ed
 .Sh SEE ALSO
 .Xr geom 4 ,
 .Xr loader.conf 5 ,
 .Xr geom 8 ,
+.Xr growfs 8 ,
 .Xr mount 8 ,
 .Xr newfs 8 ,
 .Xr sysctl 8 ,
diff --git a/sbin/geom/class/concat/geom_concat.c b/sbin/geom/class/concat/geom_concat.c
index bf4687e..4157cea 100644
--- a/sbin/geom/class/concat/geom_concat.c
+++ b/sbin/geom/class/concat/geom_concat.c
@@ -55,7 +55,7 @@ struct g_command class_commands[] = {
 	    "[-v] prov ..."
 	},
 	{ "create", G_FLAG_VERBOSE | G_FLAG_LOADKLD, NULL, G_NULL_OPTS,
-	    "[-v] name prov prov ..."
+	    "[-v] name prov ..."
 	},
 	{ "destroy", G_FLAG_VERBOSE, NULL,
 	    {
@@ -72,7 +72,7 @@ struct g_command class_commands[] = {
 		{ 'h', "hardcode", NULL, G_TYPE_NONE },
 		G_OPT_SENTINEL
 	    },
-	    "[-hv] name prov prov ..."
+	    "[-hv] name prov ..."
 	},
 	{ "stop", G_FLAG_VERBOSE, NULL,
 	    {
@@ -118,7 +118,7 @@ concat_label(struct gctl_req *req)
 	int error, i, hardcode, nargs;
 
 	nargs = gctl_get_int(req, "nargs");
-	if (nargs <= 2) {
+	if (nargs < 2) {
 		gctl_error(req, "Too few arguments.");
 		return;
 	}