NFSv4.2: Serialise O_DIRECT i/o and clone range

Ensure that all O_DIRECT reads and writes complete before cloning a file
range, so that both the source and destination are up to date.

Fixes: a5864c999d ("NFS: Do not serialise O_DIRECT reads and writes")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/nfs4file.c

@@ -278,9 +278,11 @@ static loff_t nfs42_remap_file_range(struct file *src_file, loff_t src_off,
 	lock_two_nondirectories(src_inode, dst_inode);
 	/* flush all pending writes on both src and dst so that server
 	 * has the latest data */
+	nfs_file_block_o_direct(NFS_I(src_inode));
 	ret = nfs_sync_inode(src_inode);
 	if (ret)
 		goto out_unlock;
+	nfs_file_block_o_direct(NFS_I(dst_inode));
 	ret = nfs_sync_inode(dst_inode);
 	if (ret)
 		goto out_unlock;