From: Christoph Hellwig Subject: fallocate vs O_(D)SYNC Date: Wed, 16 Nov 2011 03:42:56 -0500 Message-ID: <20111116084256.GA22963@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, mfasheh@suse.com, jlbec@evilplan.org, cluster-devel@redhat.com Return-path: Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:41046 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755100Ab1KPIm7 (ORCPT ); Wed, 16 Nov 2011 03:42:59 -0500 Content-Disposition: inline Sender: linux-ext4-owner@vger.kernel.org List-ID: It seems all filesystems but XFS ignore O_SYNC for fallocate, and never make sure the size update transaction made it to disk. Given that a fallocate without FALLOC_FL_KEEP_SIZE very much is a data operation (it adds new blocks that return zeroes) that seems like a fairly nasty surprise for O_SYNC users.