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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 41C07C43470 for ; Wed, 19 May 2021 00:51:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 251EF613AA for ; Wed, 19 May 2021 00:51:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233321AbhESAwg (ORCPT ); Tue, 18 May 2021 20:52:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54012 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352876AbhESAvW (ORCPT ); Tue, 18 May 2021 20:51:22 -0400 Received: from zeniv-ca.linux.org.uk (zeniv-ca.linux.org.uk [IPv6:2607:5300:60:148a::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 31763C06175F; Tue, 18 May 2021 17:50:03 -0700 (PDT) Received: from viro by zeniv-ca.linux.org.uk with local (Exim 4.94 #2 (Red Hat Linux)) id 1ljAOT-00G4FW-HH; Wed, 19 May 2021 00:49:01 +0000 From: Al Viro To: Linus Torvalds Cc: Jia He , Petr Mladek , Steven Rostedt , Sergey Senozhatsky , Andy Shevchenko , Rasmus Villemoes , Jonathan Corbet , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , "Eric W . Biederman" , "Darrick J. Wong" , "Peter Zijlstra (Intel)" , Ira Weiny , Eric Biggers , "Ahmed S. Darwish" , "open list:DOCUMENTATION" , Linux Kernel Mailing List , linux-s390 , linux-fsdevel Subject: [PATCH 02/14] d_path: saner calling conventions for __dentry_path() Date: Wed, 19 May 2021 00:48:49 +0000 Message-Id: <20210519004901.3829541-2-viro@zeniv.linux.org.uk> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210519004901.3829541-1-viro@zeniv.linux.org.uk> References: <20210519004901.3829541-1-viro@zeniv.linux.org.uk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 1) lift NUL-termination into the callers 2) pass pointer to the end of buffer instead of that to beginning. (1) allows to simplify dentry_path() - we don't need to play silly games with restoring the leading / of "//deleted" after __dentry_path() would've overwritten it with NUL. We also do not need to check if (either) prepend() in there fails - if the buffer is not large enough, we'll end with negative buflen after prepend() and __dentry_path() will return the right value (ERR_PTR(-ENAMETOOLONG)) just fine. Signed-off-by: Al Viro --- fs/d_path.c | 33 +++++++++++++-------------------- 1 file changed, 13 insertions(+), 20 deletions(-) diff --git a/fs/d_path.c b/fs/d_path.c index 01df5dfa1f88..1a1cf05e7780 100644 --- a/fs/d_path.c +++ b/fs/d_path.c @@ -326,22 +326,21 @@ char *simple_dname(struct dentry *dentry, char *buffer, int buflen) /* * Write full pathname from the root of the filesystem into the buffer. */ -static char *__dentry_path(const struct dentry *d, char *buf, int buflen) +static char *__dentry_path(const struct dentry *d, char *p, int buflen) { const struct dentry *dentry; char *end, *retval; int len, seq = 0; int error = 0; - if (buflen < 2) + if (buflen < 1) goto Elong; rcu_read_lock(); restart: dentry = d; - end = buf + buflen; + end = p; len = buflen; - prepend(&end, &len, "", 1); /* Get '/' right */ retval = end-1; *retval = '/'; @@ -373,27 +372,21 @@ static char *__dentry_path(const struct dentry *d, char *buf, int buflen) char *dentry_path_raw(const struct dentry *dentry, char *buf, int buflen) { - return __dentry_path(dentry, buf, buflen); + char *p = buf + buflen; + prepend(&p, &buflen, "", 1); + return __dentry_path(dentry, p, buflen); } EXPORT_SYMBOL(dentry_path_raw); char *dentry_path(const struct dentry *dentry, char *buf, int buflen) { - char *p = NULL; - char *retval; - - if (d_unlinked(dentry)) { - p = buf + buflen; - if (prepend(&p, &buflen, "//deleted", 10) != 0) - goto Elong; - buflen++; - } - retval = __dentry_path(dentry, buf, buflen); - if (!IS_ERR(retval) && p) - *p = '/'; /* restore '/' overriden with '\0' */ - return retval; -Elong: - return ERR_PTR(-ENAMETOOLONG); + char *p = buf + buflen; + + if (unlikely(d_unlinked(dentry))) + prepend(&p, &buflen, "//deleted", 10); + else + prepend(&p, &buflen, "", 1); + return __dentry_path(dentry, p, buflen); } static void get_fs_root_and_pwd_rcu(struct fs_struct *fs, struct path *root, -- 2.11.0