btrfs: Add datacow mount option.

Add datacow mount option to enable copy-on-write with
remount option.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/Documentation/filesystems/btrfs.txt b/Documentation/filesystems/btrfs.txt
index 79c08f368ace..bbd1f0f57ce9 100644
--- a/Documentation/filesystems/btrfs.txt
+++ b/Documentation/filesystems/btrfs.txt
@@ -154,9 +154,10 @@ Options with (*) are default options and will not show in the mount options.
         (non-battery-backed) write-back cache, nobarrier option will lead to
         filesystem corruption on a system crash or power loss.
 
+  datacow(*)
   nodatacow
-        Disable data copy-on-write for newly created files.  Implies nodatasum,
-        and disables all compression.
+        Enable/disable data copy-on-write for newly created files.
+        Nodatacow implies nodatasum, and disables all compression.
 
   nodatasum
         Disable data checksumming for newly created files.