From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 9 Sep 2001 22:33:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 9 Sep 2001 22:33:13 -0400 Received: from humbolt.nl.linux.org ([131.211.28.48]:12293 "EHLO humbolt.nl.linux.org") by vger.kernel.org with ESMTP id ; Sun, 9 Sep 2001 22:32:57 -0400 Content-Type: text/plain; charset=US-ASCII From: Daniel Phillips To: Chris Mason , Andrea Arcangeli Subject: Re: linux-2.4.10-pre5 Date: Mon, 10 Sep 2001 04:40:21 +0200 X-Mailer: KMail [version 1.3.1] Cc: Linus Torvalds , Andreas Dilger , Kernel Mailing List In-Reply-To: <20010910001556Z16150-26183+680@humbolt.nl.linux.org> <20010910021513Z16066-26183+696@humbolt.nl.linux.org> <1324600000.1000088434@tiny> In-Reply-To: <1324600000.1000088434@tiny> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Message-Id: <20010910023312Z16066-26183+700@humbolt.nl.linux.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On September 10, 2001 04:20 am, Chris Mason wrote: > On Monday, September 10, 2001 04:22:25 AM +0200 Daniel Phillips > wrote: > > > On September 10, 2001 04:15 am, Daniel Phillips wrote: > >> On September 10, 2001 03:55 am, Andrea Arcangeli wrote: > >> > getblk should unconditionally alloc a new bh entity and only care to > >> > map it to the right cache backing store with a pagecache hash lookup. > >> > >> To feel anything like the original the new getblk has to be idempotent: > >> subsequent calls return the same block. > > > > Err, buffer_head > > How about subsequent calls for the same offset with the same blocksize need > to return the same buffer head? Are we picking nits? Better add "the same dev" and "until the buffer head is freed" ;-) I've always felt that passing the blocksize and hashing on it is just a little bizarre. This means for example that you can have two 2K buffers overlaid on a 4K buffer, and they will be entirely non-coherent. If we substitute "mapping" where "dev" goes we wouldn't need the size any more. We could still take it and just BUG if it doesn't match the mapping. Bearing in mind Linus's comments about the liklihood that we might see mixed block sizes in a single mapping something in the future. -- Daniel