btrfs: Add "barrier" option to support "-o remount,barrier"

[cascardo/linux.git] / Documentation / filesystems / btrfs.txt

diff --git a/Documentation/filesystems/btrfs.txt b/Documentation/filesystems/btrfs.txt
index 5dd282d..ce487a2 100644 (file)
--- a/Documentation/filesystems/btrfs.txt
+++ b/Documentation/filesystems/btrfs.txt
@@ -38,7 +38,7 @@ Mount Options
 =============
 
 When mounting a btrfs filesystem, the following option are accepted.
-Unless otherwise specified, all options default to off.
+Options with (*) are default options and will not show in the mount options.
 
   alloc_start=<bytes>
        Debugging option to force all block allocations above a certain
@@ -138,12 +138,13 @@ Unless otherwise specified, all options default to off.
        Disable support for Posix Access Control Lists (ACLs).  See the
        acl(5) manual page for more information about ACLs.
 
+  barrier(*)
   nobarrier
-        Disables the use of block layer write barriers.  Write barriers ensure
-       that certain IOs make it through the device cache and are on persistent
-       storage.  If used on a device with a volatile (non-battery-backed)
-       write-back cache, this option will lead to filesystem corruption on a
-       system crash or power loss.
+        Enable/disable the use of block layer write barriers.  Write barriers
+       ensure that certain IOs make it through the device cache and are on
+       persistent storage. If disabled on a device with a volatile
+       (non-battery-backed) write-back cache, nobarrier option will lead to
+       filesystem corruption on a system crash or power loss.
 
   nodatacow
        Disable data copy-on-write for newly created files.  Implies nodatasum,