Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751885AbaLQIYp (ORCPT ); Wed, 17 Dec 2014 03:24:45 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:36616 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751860AbaLQIYn (ORCPT ); Wed, 17 Dec 2014 03:24:43 -0500 Date: Wed, 17 Dec 2014 00:24:37 -0800 From: Christoph Hellwig To: Al Viro Cc: Omar Sandoval , Jan Kara , Andrew Morton , Trond Myklebust , David Sterba , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/8] swap: lock i_mutex for swap_writepage direct_IO Message-ID: <20141217082437.GA9301@infradead.org> References: <20141215162705.GA23887@quack.suse.cz> <20141215165615.GA19041@infradead.org> <20141215221100.GA4637@mew> <20141216083543.GA32425@infradead.org> <20141216085624.GA25256@mew> <20141217080610.GA20335@infradead.org> <20141217082020.GH22149@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141217082020.GH22149@ZenIV.linux.org.uk> 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 Wed, Dec 17, 2014 at 08:20:21AM +0000, Al Viro wrote: > Where the hell would those other references come from? We open the damn > thing in sys_swapon(), never put it into descriptor tables, etc. and > the only reason why we use filp_close() instead of fput() is that we > would miss ->flush() otherwise. > > Said that, why not simply *open* it with O_DIRECT to start with and be done > with that? It's not as if those guys came preopened by caller - swapon(2) > gets a pathname and does opening itself. Oops, should have dug deeper into the code. For some reason I assumed the fd is passed in from userspace. The suggestion from Al is much better, given that we never do normal I/O on the swapfile, just the bmap + direct bio submission which I hope could go away in favor of the direct I/O variant in the long run. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/