From mboxrd@z Thu Jan 1 00:00:00 1970 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: Content-Disposition: inline In-Reply-To: <20081015192254.GL15064@parisc-linux.org> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org 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 :(