From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6EBBEC433DF for ; Thu, 27 Aug 2020 15:29:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4968822D02 for ; Thu, 27 Aug 2020 15:29:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Rg8dPWnv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728306AbgH0P3M (ORCPT ); Thu, 27 Aug 2020 11:29:12 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:36436 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728209AbgH0P3J (ORCPT ); Thu, 27 Aug 2020 11:29:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1598542148; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=+kaDLLF1f55NCIko0/llJRLFGMqoBN4rwHWmAV1FCCk=; b=Rg8dPWnvEeLX1llNiml570V9KpythOZmDUSRLvdYNxGdVBtyN/tA2dR3buY75cREjoyE9M BHCxE5WxPIL1jnCwkjL/9CfvPfJhy9dx/naVGj1EMKTfBIAnjzMGVML40PUUErtV/qZ/2W 2XIuiktfq7iEFjhr0g0SNEKy/lfa+9A= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-425-9dtdZprBOgSEsWY5L1TUOg-1; Thu, 27 Aug 2020 11:29:05 -0400 X-MC-Unique: 9dtdZprBOgSEsWY5L1TUOg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 56CE310ABDC2; Thu, 27 Aug 2020 15:29:02 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-127.rdu2.redhat.com [10.10.120.127]) by smtp.corp.redhat.com (Postfix) with ESMTP id 14FE85C1C2; Thu, 27 Aug 2020 15:28:55 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20200810164044.GA31753@lst.de> References: <20200810164044.GA31753@lst.de> <1851200.1596472222@warthog.procyon.org.uk> <447452.1596109876@warthog.procyon.org.uk> <667820.1597072619@warthog.procyon.org.uk> To: Christoph Hellwig Cc: dhowells@redhat.com, Alexander Viro , Matthew Wilcox , Jeff Layton , Dave Wysochanski , Trond Myklebust , Anna Schumaker , Steve French , Eric Van Hensbergen , linux-cachefs@redhat.com, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [GIT PULL] fscache rewrite -- please drop for now MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <1428310.1598542135.1@warthog.procyon.org.uk> Date: Thu, 27 Aug 2020 16:28:55 +0100 Message-ID: <1428311.1598542135@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Christoph Hellwig wrote: > FYI, a giant rewrite dropping support for existing consumer is always > rather awkward. Is there any way you could pre-stage some infrastructure > changes, and then do a temporary fscache2, which could then be renamed > back to fscache once everyone switched over? That's a bit tricky. There are three points that would have to be shared: the userspace miscdev interface, the backing filesystem and the single index tree. It's probably easier to just have a go at converting 9P and cifs. Making the old and new APIs share would be a fairly hefty undertaking in its own right. David