Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 6 Feb 2001 20:31:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 6 Feb 2001 20:31:46 -0500 Received: from zeus.kernel.org ([209.10.41.242]:54976 "EHLO zeus.kernel.org") by vger.kernel.org with ESMTP id ; Tue, 6 Feb 2001 20:31:35 -0500 Date: Wed, 7 Feb 2001 01:27:10 +0000 From: "Stephen C. Tweedie" To: Linus Torvalds Cc: "Stephen C. Tweedie" , Ingo Molnar , Ben LaHaise , Alan Cox , Manfred Spraul , Steve Lord , Linux Kernel List , kiobuf-io-devel@lists.sourceforge.net, Ingo Molnar Subject: Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait Message-ID: <20010207012710.N1167@redhat.com> In-Reply-To: <20010207002107.L1167@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2i In-Reply-To: ; from torvalds@transmeta.com on Tue, Feb 06, 2001 at 04:41:21PM -0800 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Tue, Feb 06, 2001 at 04:41:21PM -0800, Linus Torvalds wrote: > > On Wed, 7 Feb 2001, Stephen C. Tweedie wrote: > > No, it is a problem of the ll_rw_block interface: buffer_heads need to > > be aligned on disk at a multiple of their buffer size. > > Ehh.. True of ll_rw_block() and submit_bh(), which are meant for the > traditional block device setup, where "b_blocknr" is the "virtual > blocknumber" and that indeed is tied in to the block size. > > The fact is, if you have problems like the above, then you don't > understand the interfaces. And it sounds like you designed kiobuf support > around the wrong set of interfaces. They used the only interfaces available at the time... > If you want to get at the _sector_ level, then you do ... > which doesn't look all that complicated to me. What's the problem? Doesn't this break nastily as soon as the IO hits an LVM or soft raid device? I don't think we are safe if we create a larger-sized buffer_head which spans a raid stripe: the raid mapping is only applied once per buffer_head. --Stephen - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/