From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754286AbaIPNpm (ORCPT ); Tue, 16 Sep 2014 09:45:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56893 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754220AbaIPNpk (ORCPT ); Tue, 16 Sep 2014 09:45:40 -0400 From: Jeff Moyer To: Milosz Tanski Cc: LKML , Christoph Hellwig , "linux-fsdevel\@vger.kernel.org" , linux-aio@kvack.org, Mel Gorman , Volker Lendecke , Tejun Heo , michael.kerrisk@gmail.com Subject: Re: [RFC PATCH 0/7] Non-blockling buffered fs read (page cache only) References: X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Tue, 16 Sep 2014 09:44:57 -0400 In-Reply-To: (Milosz Tanski's message of "Mon, 15 Sep 2014 18:27:07 -0400") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Milosz Tanski writes: > Jeff, > > This patchset creates a new read (readv2/preadv2) syscall(s) that take > a extra flag argument (kind of like recvmsg). What it doesn't do is > change the current behavior of of the O_NONBLOCK, if the file is > open() with O_NONBLOCK flag. It shouldn't break any existing > applications since you have to opt into using this by using the new > syscall. Hi, Milosz, Ah, I misread one of the patches. Now that I've applied the series, I see that you're testing the flag argument, not the file open flags. > I don't have a preference either way if we should create a new flag or > re-use O_NONBLOCK the flag. Instead, I'm hoping to get some consensus > here from senior kernel developers like yourself. Maybe a RWF_NONBLOCK > (I'm stealing from eventfd, EFD_NONBLOCK). I think I'd rather name the flag something other than O_NONBLOCK, if for no other reason that to avoid confusion. > As a side note, I noticed that EFD_NONBLOCK, SFD_NONBLOCK, etc... all > alias to the value of O_NONBLOCK and there's a bunch of bug checks in > the code like this: > BUILD_BUG_ON(EFD_NONBLOCK != O_NONBLOCK); That's because the flag is passed on to anon_inode_getfile. See also this define: #define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK) A general note on your subjects -- you should make them more specific to the subsystem you're updating. Commit titles like "documentation update" are a bit too broad. ;-) Cheers, Jeff