Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761736AbYASAwZ (ORCPT ); Fri, 18 Jan 2008 19:52:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757481AbYASAwQ (ORCPT ); Fri, 18 Jan 2008 19:52:16 -0500 Received: from waste.org ([66.93.16.53]:43611 "EHLO waste.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757260AbYASAwO (ORCPT ); Fri, 18 Jan 2008 19:52:14 -0500 Subject: Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapped files From: Matt Mackall To: Rik van Riel Cc: Linus Torvalds , Ingo Oeser , Miklos Szeredi , peterz@infradead.org, salikhmetov@gmail.com, linux-mm@kvack.org, jakob@unthought.net, linux-kernel@vger.kernel.org, valdis.kletnieks@vt.edu, ksm@42.dk, staubach@redhat.com, jesper.juhl@gmail.com, akpm@linux-foundation.org, protasnb@gmail.com, r.e.wolff@bitwizard.nl, hidave.darkstar@gmail.com, hch@infradead.org In-Reply-To: <20080118175450.715ded60@bree.surriel.com> References: <12006091182260-git-send-email-salikhmetov@gmail.com> <200801182332.02945.ioe-lkml@rameria.de> <20080118175450.715ded60@bree.surriel.com> Content-Type: text/plain Date: Fri, 18 Jan 2008 18:50:03 -0600 Message-Id: <1200703803.25782.45.camel@cinder.waste.org> Mime-Version: 1.0 X-Mailer: Evolution 2.12.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1946 Lines: 56 On Fri, 2008-01-18 at 17:54 -0500, Rik van Riel wrote: > On Fri, 18 Jan 2008 14:47:33 -0800 (PST) > Linus Torvalds wrote: > > > - keep it simple. Let's face it, Linux has never ever given those > > guarantees before, and it's not is if anybody has really cared. Even > > now, the issue seems to be more about paper standards conformance than > > anything else. > > There is one issue which is way more than just standards conformance. > > When a program changes file data through mmap(), at some point the > mtime needs to be update so that backup programs know to back up the > new version of the file. > > Backup programs not seeing an updated mtime is a really big deal. And that's fixed with the 4-line approach. Reminds me, I've got a patch here for addressing that problem with loop mounts: Writes to loop should update the mtime of the underlying file. Signed-off-by: Matt Mackall Index: l/drivers/block/loop.c =================================================================== --- l.orig/drivers/block/loop.c 2007-11-05 17:50:07.000000000 -0600 +++ l/drivers/block/loop.c 2007-11-05 19:03:51.000000000 -0600 @@ -221,6 +221,7 @@ static int do_lo_send_aops(struct loop_d offset = pos & ((pgoff_t)PAGE_CACHE_SIZE - 1); bv_offs = bvec->bv_offset; len = bvec->bv_len; + file_update_time(file); while (len > 0) { sector_t IV; unsigned size; @@ -299,6 +300,7 @@ static int __do_lo_send_write(struct fil set_fs(get_ds()); bw = file->f_op->write(file, buf, len, &pos); + file_update_time(file); set_fs(old_fs); if (likely(bw == len)) return 0; -- Mathematics is the supreme nostalgia of our time. -- 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/