LU-10885 docs: note flock now being enabled by default

mount -o flock was made the default, but the mount.lustre(8) man-page
still said noflock is default.  Text based on comments in LU-10885 and
http://wiki.lustre.org/Mounting_a_Lustre_File_System_on_Client_Nodes.

Signed-off-by: Laura Hild <lsh@jlab.org>
Change-Id: I48bfc0260fb948771f5cf4fb8cbc6ee9588e2217
Test-Parameters: trivial
Fixes: 16fb13eb3863 ("LU-10885 llite: enable flock mount option by default")
Fixes: 3613af3e15cb ("LU-10885 llite: enable flock mount option by default")
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/51948
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Timothy Day <timday@amazon.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lustre/doc/mount.lustre.8 b/lustre/doc/mount.lustre.8
index cc1a25a..a95c05b 100644 (file)
--- a/lustre/doc/mount.lustre.8
+++ b/lustre/doc/mount.lustre.8
@@ -135,11 +135,12 @@ options:
 .TP
 .BI flock
 Enable full distributed
-.BI flock (2)
+.BR flock (2)
 support, coherent across all client nodes also using this mount option.  This
 is useful if applications need coherent userspace file locking across multiple
-client nodes, but also imposes communications overhead in order to maintain
-locking consistency between client nodes.
+client nodes, has no measurable performance impact in modern (2.x) versions of
+Lustre, is therefore the recommended mode, and is enabled by default in Lustre
+2.12.3 and newer.
 .TP
 .BI localflock
 Enable local
@@ -148,21 +149,17 @@ support, using only client-local file locking.  This is faster than mounting
 with the
 .B flock
 option, and can be used for applications that depend on functioning
-.BI flock (2)
+.BR flock (2)
 but run only on a single node.
 .TP
 .BI noflock
 Disables
-.BR flock(2)
-support entirely, and is the default option.  Applications calling
-.BR flock(2)
+.BR flock (2)
+support entirely.  Applications calling
+.BR flock (2)
 will get an
 .B ENOSYS
-error.  It is up to the administrator to choose either the
-.B localflock
-or
-.B flock
-mount option based on their requirements.  It is possible to mount clients
+error.  It is possible to mount clients
 with different options, and only those mounted with
 .B flock
 will be coherent amongst each other.