From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29322C4CECE for ; Fri, 13 Mar 2020 23:55:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 02D332074E for ; Fri, 13 Mar 2020 23:55:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728079AbgCMXzN (ORCPT ); Fri, 13 Mar 2020 19:55:13 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:50178 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727841AbgCMXyG (ORCPT ); Fri, 13 Mar 2020 19:54:06 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jCu7x-00B6eA-FP; Fri, 13 Mar 2020 23:54:05 +0000 From: Al Viro To: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Linus Torvalds Subject: [RFC][PATCH v4 59/69] pick_link(): take reserving space on stack into a new helper Date: Fri, 13 Mar 2020 23:53:47 +0000 Message-Id: <20200313235357.2646756-59-viro@ZenIV.linux.org.uk> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200313235357.2646756-1-viro@ZenIV.linux.org.uk> References: <20200313235303.GP23230@ZenIV.linux.org.uk> <20200313235357.2646756-1-viro@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Al Viro Signed-off-by: Al Viro --- fs/namei.c | 46 +++++++++++++++++++++++++--------------------- 1 file changed, 25 insertions(+), 21 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index d58e447db2f1..c27f657c6b71 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1580,6 +1580,28 @@ static inline int may_lookup(struct nameidata *nd) return inode_permission(nd->inode, MAY_EXEC); } +static int reserve_stack(struct nameidata *nd, struct path *link, unsigned seq) +{ + int error; + + if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) + return -ELOOP; + error = nd_alloc_stack(nd); + if (likely(!error)) + return 0; + if (error == -ECHILD) { + // we must grab link first + bool grabbed_link = legitimize_path(nd, link, seq); + // ... and we must unlazy to be able to clean up + error = unlazy_walk(nd); + if (unlikely(!grabbed_link)) + error = -ECHILD; + if (!error) + error = nd_alloc_stack(nd); + } + return error; +} + enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4}; static const char *pick_link(struct nameidata *nd, struct path *link, @@ -1587,31 +1609,13 @@ static const char *pick_link(struct nameidata *nd, struct path *link, { struct saved *last; const char *res; - int error; + int error = reserve_stack(nd, link, seq); - if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { - if (!(nd->flags & LOOKUP_RCU)) - path_put(link); - return ERR_PTR(-ELOOP); - } - error = nd_alloc_stack(nd); if (unlikely(error)) { - if (error == -ECHILD) { - // we must grab link first - bool grabbed_link = legitimize_path(nd, link, seq); - // ... and we must unlazy to be able to clean up - error = unlazy_walk(nd); - if (unlikely(!grabbed_link)) - error = -ECHILD; - if (!error) - error = nd_alloc_stack(nd); - } - if (error) { + if (!(nd->flags & LOOKUP_RCU)) path_put(link); - return ERR_PTR(error); - } + return ERR_PTR(error); } - last = nd->stack + nd->depth++; last->link = *link; clear_delayed_call(&last->done); -- 2.11.0