mount.8: Clarify relation between noatime and nodiratime

According to https://lwn.net/Articles/245002/ and checking Linus' git master fs/inode.c it's obvious nodiratime is redundant when mounting with noatime. Clarify that in the man page.

diff --git a/sys-utils/mount.8 b/sys-utils/mount.8
index 27839235f4b37ae058dd3b6ea4c1621d4fb05c71..4af636b592d099fbe5706e5f9c111c24f9df4e93 100644 (file)
--- a/sys-utils/mount.8
+++ b/sys-utils/mount.8
@@ -863,7 +863,8 @@ mount options.
 .TP
 .B noatime
 Do not update inode access times on this filesystem (e.g., for faster
-access on the news spool to speed up news servers).
+access on the news spool to speed up news servers). This works for all
+inode types (directories too), so implies nodiratime.
 .TP
 .B auto
 Can be mounted with the
@@ -964,7 +965,8 @@ system.
 Update directory inode access times on this filesystem.  This is the default.
 .TP
 .B nodiratime
-Do not update directory inode access times on this filesystem.
+Do not update directory inode access times on this filesystem. If noatime
+option is set, this option is not needed.
 .TP
 .B dirsync
 All directory updates within the filesystem should be done synchronously.