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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 2AE20C742BE for ; Fri, 12 Jul 2019 12:59:58 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 815D820863 for ; Fri, 12 Jul 2019 12:59:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 815D820863 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 45lY150YgZzDqxG for ; Fri, 12 Jul 2019 22:59:53 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=ftp.linux.org.uk (client-ip=195.92.253.2; helo=zeniv.linux.org.uk; envelope-from=viro@ftp.linux.org.uk; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [195.92.253.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 45lXx52fp0zDqwF for ; Fri, 12 Jul 2019 22:56:25 +1000 (AEST) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92 #3 (Red Hat Linux)) id 1hlv5c-0007Pc-Mt; Fri, 12 Jul 2019 12:55:52 +0000 Date: Fri, 12 Jul 2019 13:55:52 +0100 From: Al Viro To: Aleksa Sarai Subject: Re: [PATCH v9 05/10] namei: O_BENEATH-style path resolution flags Message-ID: <20190712125552.GL17978@ZenIV.linux.org.uk> References: <20190706145737.5299-1-cyphar@cyphar.com> <20190706145737.5299-6-cyphar@cyphar.com> <20190712043341.GI17978@ZenIV.linux.org.uk> <20190712105745.nruaftgeat6irhzr@yavin> <20190712123924.GK17978@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190712123924.GK17978@ZenIV.linux.org.uk> User-Agent: Mutt/1.11.3 (2019-02-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Alexei Starovoitov , linux-kernel@vger.kernel.org, David Howells , linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, Shuah Khan , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Tycho Andersen , Aleksa Sarai , linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-xtensa@linux-xtensa.org, Kees Cook , Arnd Bergmann , Jann Horn , linuxppc-dev@lists.ozlabs.org, linux-m68k@lists.linux-m68k.org, Andy Lutomirski , Shuah Khan , David Drysdale , Christian Brauner , "J. Bruce Fields" , linux-parisc@vger.kernel.org, linux-api@vger.kernel.org, Chanho Min , Jeff Layton , Oleg Nesterov , Eric Biederman , linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Linus Torvalds , containers@lists.linux-foundation.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, Jul 12, 2019 at 01:39:24PM +0100, Al Viro wrote: > On Fri, Jul 12, 2019 at 08:57:45PM +1000, Aleksa Sarai wrote: > > > > > @@ -2350,9 +2400,11 @@ static const char *path_init(struct nameidata *nd, unsigned flags) > > > > s = ERR_PTR(error); > > > > return s; > > > > } > > > > - error = dirfd_path_init(nd); > > > > - if (unlikely(error)) > > > > - return ERR_PTR(error); > > > > + if (likely(!nd->path.mnt)) { > > > > > > Is that a weird way of saying "if we hadn't already called dirfd_path_init()"? > > > > Yes. I did it to be more consistent with the other "have we got the > > root" checks elsewhere. Is there another way you'd prefer I do it? > > "Have we got the root" checks are inevitable evil; here you are making the > control flow in a single function hard to follow. > > I *think* what you are doing is > absolute pathname, no LOOKUP_BENEATH: > set_root > error = nd_jump_root(nd) > else > error = dirfd_path_init(nd) > return unlikely(error) ? ERR_PTR(error) : s; > which should be a lot easier to follow (not to mention shorter), but I might > be missing something in all of that. PS: if that's what's going on, I would be tempted to turn the entire path_init() part into this: if (flags & LOOKUP_BENEATH) while (*s == '/') s++; in the very beginning (plus the handling of nd_jump_root() prototype change, but that belongs with nd_jump_root() change itself, obviously). Again, I might be missing something here...