From patchwork Thu Dec 17 16:19:08 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Axboe X-Patchwork-Id: 11980175 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=-13.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNWANTED_LANGUAGE_BODY, 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 3291BC2BB48 for ; Thu, 17 Dec 2020 16:19:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F3CE02342C for ; Thu, 17 Dec 2020 16:19:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728204AbgLQQT6 (ORCPT ); Thu, 17 Dec 2020 11:19:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53432 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728109AbgLQQT5 (ORCPT ); Thu, 17 Dec 2020 11:19:57 -0500 Received: from mail-io1-xd2a.google.com (mail-io1-xd2a.google.com [IPv6:2607:f8b0:4864:20::d2a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 779EFC0617A7 for ; Thu, 17 Dec 2020 08:19:17 -0800 (PST) Received: by mail-io1-xd2a.google.com with SMTP id y5so28012196iow.5 for ; Thu, 17 Dec 2020 08:19:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=l3Iugrzv5AcZw4A0i3n4W+/08URx3AE48WmSwpXG8sU=; b=kSzEhAdr4HA8g96BObh97VBvUBN59ILBercmAOObT+DzJ7a2+1MBtlwq7ITX1ny9oG R2Cck+i5qIvf0kC5tPGDU6im9/fxitb0o+UnC87CekR5CQ0IXeGn1PqEMszuuzCtay/F +tp1uLhbKw//SLYZzx1DZgaTlwhdw86vdeLf+ZEnQZt0ZsJgxpkzIooJBfKevhHroR7P 0Orb1ZNGSNl3E479ohTYxLOi5++KhtG9ItfSECDAEZkwlde1F26uG8frbqXY2ekpem2N 5YJcXpJpD8wvTsBlr5Zyz4b6zyfPGCv+AnMsORrd2tXb5HtAfPe82SEeOUkTsJC78Mln Axng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=l3Iugrzv5AcZw4A0i3n4W+/08URx3AE48WmSwpXG8sU=; b=s1LQjliwSGuYBAtMTDAvZDn8gtPBjDxS06z5bV420lCmEXdHMtwWs48HvdLwlW2Hy1 pxCHLVeOv6bbcRaM3eWTSmbEabCJLB42Ddhff+uVaW0yGOcY0JPuGG9cRmzSg5O5qsMz lZezxANhSS96Yes42GfE1f3ddbPDrPqqUORY5fqeFbUsf6648bX90OvwFmtI+w6V6+IS DRy7+7JFjHN8chET+ksU60B5KuW5DXQgd/VVDOzScqgy0rW02NCZ6dtP/UMGKOQV6OyQ QZ/urb0XBv4MpNI2VG/1wQtMyr1w38fdlOYklCyyaH6YbD4/JzkHCvfgBtFpbB5x5+sQ e/aA== X-Gm-Message-State: AOAM530kfslbbfSXduBKaCuGGy0LFdfJLA+ZAWQz4OGfTzrvMzSmEPLL 0bdyhf6LU+1gQ/T1pUEZs6NYLvo0yHfEBQ== X-Google-Smtp-Source: ABdhPJzGjI9Ly/jySolAEMH94vSWY1+Stu7TrqiJESJV3yFOQ+d3litaJnEJXdgZfQXRGQygxac06g== X-Received: by 2002:a6b:700f:: with SMTP id l15mr11814702ioc.22.1608221956528; Thu, 17 Dec 2020 08:19:16 -0800 (PST) Received: from p1.localdomain ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id k76sm3849957ilk.36.2020.12.17.08.19.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Dec 2020 08:19:16 -0800 (PST) From: Jens Axboe To: linux-fsdevel@vger.kernel.org Cc: torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, Jens Axboe Subject: [PATCH 1/4] fs: make unlazy_walk() error handling consistent Date: Thu, 17 Dec 2020 09:19:08 -0700 Message-Id: <20201217161911.743222-2-axboe@kernel.dk> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201217161911.743222-1-axboe@kernel.dk> References: <20201217161911.743222-1-axboe@kernel.dk> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Most callers check for non-zero return, and assume it's -ECHILD (which it always will be). One caller uses the actual error return. Clean this up and make it fully consistent, by having unlazy_walk() return a bool instead. Rename it to try_to_unlazy() and return true on success, and failure on error. That's easier to read. No functional changes in this patch. Cc: Al Viro Signed-off-by: Jens Axboe --- fs/namei.c | 43 +++++++++++++++++-------------------------- 1 file changed, 17 insertions(+), 26 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 03d0e11e4f36..c31ddddcef3c 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -669,17 +669,17 @@ static bool legitimize_root(struct nameidata *nd) */ /** - * unlazy_walk - try to switch to ref-walk mode. + * try_to_unlazy - try to switch to ref-walk mode. * @nd: nameidata pathwalk data - * Returns: 0 on success, -ECHILD on failure + * Returns: true on success, false on failure * - * unlazy_walk attempts to legitimize the current nd->path and nd->root + * try_to_unlazy attempts to legitimize the current nd->path and nd->root * for ref-walk mode. * Must be called from rcu-walk context. - * Nothing should touch nameidata between unlazy_walk() failure and + * Nothing should touch nameidata between try_to_unlazy() failure and * terminate_walk(). */ -static int unlazy_walk(struct nameidata *nd) +static bool try_to_unlazy(struct nameidata *nd) { struct dentry *parent = nd->path.dentry; @@ -694,14 +694,14 @@ static int unlazy_walk(struct nameidata *nd) goto out; rcu_read_unlock(); BUG_ON(nd->inode != parent->d_inode); - return 0; + return true; out1: nd->path.mnt = NULL; nd->path.dentry = NULL; out: rcu_read_unlock(); - return -ECHILD; + return false; } /** @@ -792,7 +792,7 @@ static int complete_walk(struct nameidata *nd) */ if (!(nd->flags & (LOOKUP_ROOT | LOOKUP_IS_SCOPED))) nd->root.mnt = NULL; - if (unlikely(unlazy_walk(nd))) + if (!try_to_unlazy(nd)) return -ECHILD; } @@ -1466,7 +1466,7 @@ static struct dentry *lookup_fast(struct nameidata *nd, unsigned seq; dentry = __d_lookup_rcu(parent, &nd->last, &seq); if (unlikely(!dentry)) { - if (unlazy_walk(nd)) + if (!try_to_unlazy(nd)) return ERR_PTR(-ECHILD); return NULL; } @@ -1567,10 +1567,8 @@ static inline int may_lookup(struct nameidata *nd) { if (nd->flags & LOOKUP_RCU) { int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); - if (err != -ECHILD) + if (err != -ECHILD || !try_to_unlazy(nd)) return err; - if (unlazy_walk(nd)) - return -ECHILD; } return inode_permission(nd->inode, MAY_EXEC); } @@ -1592,7 +1590,7 @@ static int reserve_stack(struct nameidata *nd, struct path *link, unsigned seq) // unlazy even if we fail to grab the link - cleanup needs it bool grabbed_link = legitimize_path(nd, link, seq); - if (unlazy_walk(nd) != 0 || !grabbed_link) + if (!try_to_unlazy(nd) != 0 || !grabbed_link) return -ECHILD; if (nd_alloc_stack(nd)) @@ -1634,7 +1632,7 @@ static const char *pick_link(struct nameidata *nd, struct path *link, touch_atime(&last->link); cond_resched(); } else if (atime_needs_update(&last->link, inode)) { - if (unlikely(unlazy_walk(nd))) + if (!try_to_unlazy(nd)) return ERR_PTR(-ECHILD); touch_atime(&last->link); } @@ -1651,11 +1649,8 @@ static const char *pick_link(struct nameidata *nd, struct path *link, get = inode->i_op->get_link; if (nd->flags & LOOKUP_RCU) { res = get(NULL, inode, &last->done); - if (res == ERR_PTR(-ECHILD)) { - if (unlikely(unlazy_walk(nd))) - return ERR_PTR(-ECHILD); + if (res == ERR_PTR(-ECHILD) && try_to_unlazy(nd)) res = get(link->dentry, inode, &last->done); - } } else { res = get(link->dentry, inode, &last->done); } @@ -2193,7 +2188,7 @@ static int link_path_walk(const char *name, struct nameidata *nd) } if (unlikely(!d_can_lookup(nd->path.dentry))) { if (nd->flags & LOOKUP_RCU) { - if (unlazy_walk(nd)) + if (!try_to_unlazy(nd)) return -ECHILD; } return -ENOTDIR; @@ -3127,7 +3122,6 @@ static const char *open_last_lookups(struct nameidata *nd, struct inode *inode; struct dentry *dentry; const char *res; - int error; nd->flags |= op->intent; @@ -3151,9 +3145,8 @@ static const char *open_last_lookups(struct nameidata *nd, } else { /* create side of things */ if (nd->flags & LOOKUP_RCU) { - error = unlazy_walk(nd); - if (unlikely(error)) - return ERR_PTR(error); + if (!try_to_unlazy(nd)) + return ERR_PTR(-ECHILD); } audit_inode(nd->name, dir, AUDIT_INODE_PARENT); /* trailing slashes? */ @@ -3162,9 +3155,7 @@ static const char *open_last_lookups(struct nameidata *nd, } if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { - error = mnt_want_write(nd->path.mnt); - if (!error) - got_write = true; + got_write = !mnt_want_write(nd->path.mnt); /* * do _not_ fail yet - we might not need that or fail with * a different error; let lookup_open() decide; we'll be