don't modify od->filp at all

make put_filp() conditional on flag set by finish_open()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -2708,10 +2708,8 @@ static struct file *path_openat(int dfd, const char *pathname,
 		path_put(&nd->root);
 	if (base)
 		fput(base);
-	if (od.filp) {
-		BUG_ON(od.filp->f_path.dentry);
+	if (!(opened & FILE_OPENED))
 		put_filp(od.filp);
-	}
 	if (res == ERR_PTR(-EOPENSTALE)) {
 		if (flags & LOOKUP_RCU)
 			res = ERR_PTR(-ECHILD);

fs/open.c

@@ -786,15 +786,14 @@ struct file *finish_open(struct opendata *od, struct dentry *dentry,
 			 int *opened)
 {
 	struct file *res;
+	BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
 
 	mntget(od->mnt);
 	dget(dentry);
 
 	res = do_dentry_open(dentry, od->mnt, od->filp, open, current_cred());
-	if (!IS_ERR(res)) {
+	if (!IS_ERR(res))
 		*opened |= FILE_OPENED;
-		od->filp = NULL;
-	}
 
 	return res;
 }