btrfs-progs: update device scan usage

the btrfs device scan usage didnt publish --all-devices
option so add it

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

diff --git a/cmds-device.c b/cmds-device.c
index 3a694be..4bbf401 100644 (file)
--- a/cmds-device.c
+++ b/cmds-device.c
@@ -180,7 +180,7 @@ static int cmd_rm_dev(int argc, char **argv)
 }
 
 static const char * const cmd_scan_dev_usage[] = {
-       "btrfs device scan [<device>...]",
+       "btrfs device scan [<--all-devices>|<device> [<device>...]]",
        "Scan devices for a btrfs filesystem",
        NULL
 };