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>

diff --git a/Documentation/filesystems/btrfs.txt b/Documentation/filesystems/btrfs.txt
index 79c08f3..bbd1f0f 100644 (file)
--- 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.

diff --cc fs/btrfs/super.c
Simple merge