vfs: do_last(): only return EISDIR for O_CREAT

This allows this code to be shared between O_CREAT and plain opens.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -2384,7 +2384,7 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
 	if (error)
 		return ERR_PTR(error);
 	error = -EISDIR;
-	if (S_ISDIR(nd->inode->i_mode))
+	if ((open_flag & O_CREAT) && S_ISDIR(nd->inode->i_mode))
 		goto exit;
 	error = -ENOTDIR;
 	if ((nd->flags & LOOKUP_DIRECTORY) && !nd->inode->i_op->lookup)