Btrfs: make sure NODATACOW also gets NODATASUM set

A user reported hitting the BUG_ON() in btrfs_finished_ordered_io() where we had
csums on a NOCOW extent.  This can happen if we have NODATACOW set but not
NODATASUM set, which can happen in two cases, either we mount with -o nodatacow
and then write into preallocated space, or chattr +C a directory and move a file
into that directory.  Liu has fixed the move case in a different place, but this
fixes the mount -o nodatacow case.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>

fs/btrfs/inode.c

@@ -5574,7 +5574,8 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
 		if (btrfs_test_opt(root, NODATASUM))
 			BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM;
 		if (btrfs_test_opt(root, NODATACOW))
-			BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW;
+			BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW |
+				BTRFS_INODE_NODATASUM;
 	}
 
 	insert_inode_hash(inode);