From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760868Ab3GaWY5 (ORCPT ); Wed, 31 Jul 2013 18:24:57 -0400 Received: from imap.thunk.org ([74.207.234.97]:37601 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753892Ab3GaWY4 (ORCPT ); Wed, 31 Jul 2013 18:24:56 -0400 X-Greylist: delayed 1319 seconds by postgrey-1.27 at vger.kernel.org; Wed, 31 Jul 2013 18:24:56 EDT Date: Wed, 31 Jul 2013 18:01:54 -0400 From: "Theodore Ts'o" To: Namjae Jeon Cc: adilger.kernel@dilger.ca, bpm@sgi.com, elder@kernel.org, hch@infradead.org, david@fromorbit.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, xfs@oss.sgi.com, a.sangwan@samsung.com, Namjae Jeon Subject: Re: [PATCH 1/3] fs: Introduce new flag FALLOC_FL_COLLAPSE_RANGE Message-ID: <20130731220154.GA11378@thunk.org> Mail-Followup-To: Theodore Ts'o , Namjae Jeon , adilger.kernel@dilger.ca, bpm@sgi.com, elder@kernel.org, hch@infradead.org, david@fromorbit.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, xfs@oss.sgi.com, a.sangwan@samsung.com, Namjae Jeon References: <1375281721-15840-1-git-send-email-linkinjeon@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1375281721-15840-1-git-send-email-linkinjeon@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@thunk.org X-SA-Exim-Scanned: No (on imap.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Have you considered what happens if you have a 10 megabyte file, of which the first 5 megs are mmap'ed into a userspace process. Now suppose you call COLLAPASE_RANGE on a one megabyte range starting at offset 1024k from the beginning of the file. Does the right thing happen to the mmap'ed region in memory? Cheers, - Ted