From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: Re: [PATCH v9 05/10] namei: O_BENEATH-style path resolution flags Date: Fri, 12 Jul 2019 16:00:27 +0100 Message-ID: <20190712150026.GO17978@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> <20190712125552.GL17978@ZenIV.linux.org.uk> <20190712132553.GN17978@ZenIV.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190712132553.GN17978@ZenIV.linux.org.uk> Sender: linux-kernel-owner@vger.kernel.org To: Aleksa Sarai Cc: Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Christian Brauner , David Drysdale , Andy Lutomirski , Linus Torvalds , Eric Biederman , Andrew Morton , Alexei Starovoitov , Kees Cook , Jann Horn , Tycho Andersen , Chanho Min , Oleg Nesterov , Aleksa Sarai , containers@lists.linux-foundation.org, linux-alpha@vger.kernel.org List-Id: linux-arch.vger.kernel.org On Fri, Jul 12, 2019 at 02:25:53PM +0100, Al Viro wrote: > if (flags & LOOKUP_BENEATH) { > nd->root = nd->path; > if (!(flags & LOOKUP_RCU)) > path_get(&nd->root); > else > nd->root_seq = nd->seq; BTW, this assignment is needed for LOOKUP_RCU case. Without it you are pretty much guaranteed that lazy pathwalk will fail, when it comes to complete_walk(). Speaking of which, what would happen if LOOKUP_ROOT/LOOKUP_BENEATH combination would someday get passed? From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from zeniv.linux.org.uk ([195.92.253.2]:39588 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727035AbfGLPAx (ORCPT ); Fri, 12 Jul 2019 11:00:53 -0400 Date: Fri, 12 Jul 2019 16:00:27 +0100 From: Al Viro Subject: Re: [PATCH v9 05/10] namei: O_BENEATH-style path resolution flags Message-ID: <20190712150026.GO17978@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> <20190712125552.GL17978@ZenIV.linux.org.uk> <20190712132553.GN17978@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190712132553.GN17978@ZenIV.linux.org.uk> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Aleksa Sarai Cc: Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Christian Brauner , David Drysdale , Andy Lutomirski , Linus Torvalds , Eric Biederman , Andrew Morton , Alexei Starovoitov , Kees Cook , Jann Horn , Tycho Andersen , Chanho Min , Oleg Nesterov , Aleksa Sarai , containers@lists.linux-foundation.org, linux-alpha@vger.kernel.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, sparclinux@vger.kernel.org Message-ID: <20190712150027.dGnITDnvUC88irXOSU2g6RDIZ4HRecot-OImsgsSLNc@z> On Fri, Jul 12, 2019 at 02:25:53PM +0100, Al Viro wrote: > if (flags & LOOKUP_BENEATH) { > nd->root = nd->path; > if (!(flags & LOOKUP_RCU)) > path_get(&nd->root); > else > nd->root_seq = nd->seq; BTW, this assignment is needed for LOOKUP_RCU case. Without it you are pretty much guaranteed that lazy pathwalk will fail, when it comes to complete_walk(). Speaking of which, what would happen if LOOKUP_ROOT/LOOKUP_BENEATH combination would someday get passed?