Merge branch 'master' into for-linus

[pandora-kernel.git] / Documentation / filesystems / ext3.txt

diff --git a/Documentation/filesystems/ext3.txt b/Documentation/filesystems/ext3.txt
index 867c5b5..272f80d 100644 (file)
--- a/Documentation/filesystems/ext3.txt
+++ b/Documentation/filesystems/ext3.txt
@@ -59,8 +59,19 @@ commit=nrsec (*)     Ext3 can be told to sync all its data and metadata
                        Setting it to very large values will improve
                        performance.
 
-barrier=1              This enables/disables barriers.  barrier=0 disables
-                       it, barrier=1 enables it.
+barrier=<0(*)|1>       This enables/disables the use of write barriers in
+barrier                        the jbd code.  barrier=0 disables, barrier=1 enables.
+nobarrier      (*)     This also requires an IO stack which can support
+                       barriers, and if jbd gets an error on a barrier
+                       write, it will disable again with a warning.
+                       Write barriers enforce proper on-disk ordering
+                       of journal commits, making volatile disk write caches
+                       safe to use, at some performance penalty.  If
+                       your disks are battery-backed in one way or another,
+                       disabling barriers may safely improve performance.
+                       The mount options "barrier" and "nobarrier" can
+                       also be used to enable or disable barriers, for
+                       consistency with other ext3 mount options.
 
 orlov          (*)     This enables the new Orlov block allocator. It is
                        enabled by default.