From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754402AbaIVO01 (ORCPT ); Mon, 22 Sep 2014 10:26:27 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:47808 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754199AbaIVOZW (ORCPT ); Mon, 22 Sep 2014 10:25:22 -0400 Date: Mon, 22 Sep 2014 07:25:19 -0700 From: Christoph Hellwig To: Jonathan Corbet Cc: Milosz Tanski , LKML , Christoph Hellwig , "linux-fsdevel@vger.kernel.org" , linux-aio@kvack.org, Mel Gorman , Volker Lendecke , Tejun Heo , Jeff Moyer , "Theodore Ts'o" , Al Viro Subject: Re: [RFC v2 0/5] Non-blockling buffered fs read (page cache only) Message-ID: <20140922142519.GA27920@infradead.org> References: <20140919104204.3b0bb762@lwn.net> <20140922101221.4bf46809@lwn.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140922101221.4bf46809@lwn.net> User-Agent: Mutt/1.5.23 (2014-03-12) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 22, 2014 at 10:12:21AM -0400, Jonathan Corbet wrote: > So I'm not contesting this, but I am genuinely curious: do you think > there are applications out there requesting non-blocking behavior on > regular files that will then break if they actually get non-blocking > behavior? I don't suppose you have an example? You only have to look as far as Samba, but Jeff quoted an old lkml post earlier that had other examples. source3/smbd/open.c: if (first_open_attempt && lp_kernel_oplocks(SNUM(conn))) { /* * With kernel oplocks the open breaking an oplock * blocks until the oplock holder has given up the * oplock or closed the file. We prevent this by first * trying to open the file with O_NONBLOCK (see "man * fcntl" on Linux). For the second try, triggered by * an oplock break response, we do not need this * anymore. * * This is true under the assumption that only Samba * requests kernel oplocks. Once someone else like * NFSv4 starts to use that API, we will have to * modify this by communicating with the NFSv4 server. */ flags2 |= O_NONBLOCK; } From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [RFC v2 0/5] Non-blockling buffered fs read (page cache only) Date: Mon, 22 Sep 2014 07:25:19 -0700 Message-ID: <20140922142519.GA27920@infradead.org> References: <20140919104204.3b0bb762@lwn.net> <20140922101221.4bf46809@lwn.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Milosz Tanski , LKML , Christoph Hellwig , "linux-fsdevel@vger.kernel.org" , linux-aio@kvack.org, Mel Gorman , Volker Lendecke , Tejun Heo , Jeff Moyer , Theodore Ts'o , Al Viro To: Jonathan Corbet Return-path: Content-Disposition: inline In-Reply-To: <20140922101221.4bf46809@lwn.net> Sender: owner-linux-aio@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Mon, Sep 22, 2014 at 10:12:21AM -0400, Jonathan Corbet wrote: > So I'm not contesting this, but I am genuinely curious: do you think > there are applications out there requesting non-blocking behavior on > regular files that will then break if they actually get non-blocking > behavior? I don't suppose you have an example? You only have to look as far as Samba, but Jeff quoted an old lkml post earlier that had other examples. source3/smbd/open.c: if (first_open_attempt && lp_kernel_oplocks(SNUM(conn))) { /* * With kernel oplocks the open breaking an oplock * blocks until the oplock holder has given up the * oplock or closed the file. We prevent this by first * trying to open the file with O_NONBLOCK (see "man * fcntl" on Linux). For the second try, triggered by * an oplock break response, we do not need this * anymore. * * This is true under the assumption that only Samba * requests kernel oplocks. Once someone else like * NFSv4 starts to use that API, we will have to * modify this by communicating with the NFSv4 server. */ flags2 |= O_NONBLOCK; } -- To unsubscribe, send a message with 'unsubscribe linux-aio' in the body to majordomo@kvack.org. For more info on Linux AIO, see: http://www.kvack.org/aio/ Don't email: aart@kvack.org