btrfs-progs: update help for device stats

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/cmds-device.c b/cmds-device.c
index 458c088..cbb6b61 100644 (file)
--- a/cmds-device.c
+++ b/cmds-device.c
@@ -349,7 +349,9 @@ out:
 
 static const char * const cmd_device_stats_usage[] = {
        "btrfs device stats [-z] <path>|<device>",
-       "Show current device IO stats. -z to reset stats afterwards.",
+       "Show current device IO stats.",
+       "",
+       "-z                     show current stats and reset values to zero",
        NULL
 };