diff -urNp x-ref/fs/fcntl.c x/fs/fcntl.c
--- x-ref/fs/fcntl.c	2003-01-14 03:04:09.000000000 +0100
+++ x/fs/fcntl.c	2003-01-14 03:04:12.000000000 +0100
@@ -231,6 +231,11 @@ static int setfl(int fd, struct file * f
 	}
 
 	if (arg & O_DIRECT) {
+		error = -EINVAL;
+		if (!inode->i_mapping || !inode->i_mapping->a_ops ||
+		    !inode->i_mapping->a_ops->direct_IO)
+			goto out;
+
 		if (!filp->f_iobuf) {
 			error = alloc_kiovec(1, &filp->f_iobuf);
 			if (error < 0)
diff -urNp x-ref/fs/open.c x/fs/open.c
--- x-ref/fs/open.c	2002-11-29 02:23:16.000000000 +0100
+++ x/fs/open.c	2003-01-14 03:04:12.000000000 +0100
@@ -699,6 +699,12 @@ struct file *dentry_open(struct dentry *
 	}
 	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 
+	/* NB: we're sure to have correct a_ops only after f_op->open */
+	error = -EINVAL;
+	if (f->f_flags & O_DIRECT && (!inode->i_mapping || !inode->i_mapping->a_ops ||
+				      !inode->i_mapping->a_ops->direct_IO))
+		goto cleanup_all;
+
 	return f;
 
 cleanup_all:
diff -urNp x-ref/mm/filemap.c x/mm/filemap.c
--- x-ref/mm/filemap.c	2003-01-14 03:04:11.000000000 +0100
+++ x/mm/filemap.c	2003-01-14 03:04:52.000000000 +0100
@@ -1538,8 +1538,6 @@ static ssize_t generic_file_direct_IO(in
 	retval = -EINVAL;
 	if ((offset & blocksize_mask) || (count & blocksize_mask) || ((unsigned long) buf & blocksize_mask))
 		goto out_free;
-	if (!mapping->a_ops->direct_IO)
-		goto out_free;
 
 	if ((rw == READ) && (offset + count > size))
 		count = size - offset;