Btrfs: disable snapshot aware defrag for now

commit 8101c8dbf6243ba517aab58d69bf1bc37d8b7b9c upstream.

It's just broken and it's taking a lot of effort to fix it, so for now just
disable it so people can defrag in peace.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 0bcee78..25e6a8e 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2655,7 +2655,7 @@
 			EXTENT_DEFRAG, 1, cached_state);
 	if (ret) {
 		u64 last_snapshot = btrfs_root_last_snapshot(&root->root_item);
-		if (last_snapshot >= BTRFS_I(inode)->generation)
+		if (0 && last_snapshot >= BTRFS_I(inode)->generation)
 			/* the inode is shared */
 			new = record_old_file_extents(inode, ordered_extent);