xfs: Support setting FMODE_CAN_ATOMIC_WRITE

Set FMODE_CAN_ATOMIC_WRITE flag if we can atomic write for that inode.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>	 #On ppc64

Author: johnpgarry

fs/xfs/xfs_file.c

@@ -1223,6 +1223,8 @@ xfs_file_open(
 	if (xfs_is_shutdown(XFS_M(inode->i_sb)))
 		return -EIO;
 	file->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT;
+	if (xfs_inode_can_atomicwrite(XFS_I(inode)))
+		file->f_mode |= FMODE_CAN_ATOMIC_WRITE;
 	return generic_file_open(inode, file);
 }