From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.kundenserver.de ([212.227.17.24]:61890 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751085AbcCBKzw (ORCPT ); Wed, 2 Mar 2016 05:55:52 -0500 From: Arnd Bergmann To: Christoph Hellwig Cc: "Darrick J. Wong" , axboe@kernel.dk, akpm@linux-foundation.org, torvalds@linux-foundation.org, martin.petersen@oracle.com, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, shane.seymour@hpe.com, bfields@fieldses.org, linux-fsdevel@vger.kernel.org, jlayton@poochiereds.net Subject: Re: [PATCH v5.1 0/2] create BLKZEROOUT ioctl that invalidates page cache Date: Wed, 02 Mar 2016 11:55:12 +0100 Message-ID: <3061888.dPHoQkWWFl@wuerfel> In-Reply-To: <20160302094416.GA16631@infradead.org> References: <20160302040932.16685.62789.stgit@birch.djwong.org> <1889689.0axyUkdxkf@wuerfel> <20160302094416.GA16631@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wednesday 02 March 2016 01:44:16 Christoph Hellwig wrote: > On Wed, Mar 02, 2016 at 10:15:02AM +0100, Arnd Bergmann wrote: > > I'm missing the background on this, just saw the patch fly by, > > so sorry if this has been asked before: > > > > Why do you want to invalidate the cache? Is this to save RAM > > or is something else going to write here and you have to invalidate > > it for correctness? > > BLKZEROOUT can be though as a direct I/O operation - it issues a > WRITE SAME (or similar) command straight to the device to zero > the specified range. If there was cached data for this range it would > now be stale. Ok, got it. Thanks, Arnd