From: Nick Piggin Subject: Re: minix/ext2 + rd problem Date: Thu, 16 Oct 2008 05:48:12 +0200 Message-ID: <20081016034812.GA10371@wotan.suse.de> References: <20081015041644.GA24613@wotan.suse.de> <20081015140523.GA30641@wotan.suse.de> <20081015143425.GA2316@wotan.suse.de> <20081015192254.GL15064@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Richard Kojedzinszky , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org To: Matthew Wilcox Return-path: Received: from mail.suse.de ([195.135.220.2]:42893 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752548AbYJPDs1 (ORCPT ); Wed, 15 Oct 2008 23:48:27 -0400 Content-Disposition: inline In-Reply-To: <20081015192254.GL15064@parisc-linux.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Oct 15, 2008 at 01:22:54PM -0600, Matthew Wilcox wrote: > On Wed, Oct 15, 2008 at 04:34:25PM +0200, Nick Piggin wrote: > > You can flush and invalidate the blockdev with the --flushbufs argument > > to blockdev command. However you can't use this with ramdisk devices: > > someone thought it would be a good idea to save on precious ioctl space > > and implemented totally different semantics on that device with the > > same ioctl (it throws away the underlying data as well as the cache). > > What happens if we declare that a bug and fix it (and add a new ioctl to > actually throw away the data ... oh, wait, we have one, it's BLKDISCARD)? Well... that's a good point. We probably could, because the worst someone will see is their backing store memory does not get freed. It won't munch someone's data. I'd love to do this, OTOH we've had the old behaviour, apparently documented and used by someone at some point, for a long time :(