diff -urNp --exclude CVS --exclude BitKeeper x-ref/fs/fcntl.c x/fs/fcntl.c
--- x-ref/fs/fcntl.c	2003-07-17 03:29:54.000000000 +0200
+++ x/fs/fcntl.c	2003-07-17 03:43:15.000000000 +0200
@@ -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 ||
+		    !have_mapping_directIO(inode->i_mapping))
+			goto out;
+
 		if (!filp->f_iobuf) {
 			error = alloc_kiovec(1, &filp->f_iobuf);
 			if (error < 0)
diff -urNp --exclude CVS --exclude BitKeeper x-ref/fs/open.c x/fs/open.c
--- x-ref/fs/open.c	2003-07-15 02:05:51.000000000 +0200
+++ x/fs/open.c	2003-07-17 03:42:44.000000000 +0200
@@ -701,6 +701,12 @@ 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 ||
+				      !have_mapping_directIO(inode->i_mapping)))
+		goto cleanup_all;
+
 	return f;
 
 cleanup_all:
diff -urNp --exclude CVS --exclude BitKeeper x-ref/include/linux/fs.h x/include/linux/fs.h
--- x-ref/include/linux/fs.h	2003-07-17 03:29:52.000000000 +0200
+++ x/include/linux/fs.h	2003-07-17 03:42:45.000000000 +0200
@@ -519,6 +519,11 @@ struct inode {
 	} u;
 };
 
+static inline int have_mapping_directIO(struct address_space * mapping)
+{
+	return mapping->a_ops->direct_IO || mapping->a_ops->direct_fileIO;
+}
+
 static inline void inode_add_bytes(struct inode *inode, loff_t bytes)
 {
 	inode->i_blocks += bytes >> 9;
diff -urNp --exclude CVS --exclude BitKeeper x-ref/mm/filemap.c x/mm/filemap.c
--- x-ref/mm/filemap.c	2003-07-17 03:29:56.000000000 +0200
+++ x/mm/filemap.c	2003-07-17 03:40:38.000000000 +0200
@@ -1522,11 +1522,6 @@ no_cached_page:
 	UPDATE_ATIME(inode);
 }
 
-static inline int have_mapping_directIO(struct address_space * mapping)
-{
-	return mapping->a_ops->direct_IO || mapping->a_ops->direct_fileIO;
-}
-
 /* Switch between old and new directIO formats */
 static inline int do_call_directIO(int rw, struct file *filp, struct kiobuf *iobuf, unsigned long offset, int blocksize)
 {
@@ -1573,8 +1568,6 @@ 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 (!have_mapping_directIO(mapping))
-		goto out_free;
 
 	if ((rw == READ) && (offset + count > size))
 		count = size - offset;