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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10EBDC433FE for ; Tue, 19 Oct 2021 19:01:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E404B6137D for ; Tue, 19 Oct 2021 19:01:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233744AbhJSTDf (ORCPT ); Tue, 19 Oct 2021 15:03:35 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:34195 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232717AbhJSTDf (ORCPT ); Tue, 19 Oct 2021 15:03:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634670081; 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=luTsdgmE900iDsk4r7Drx7azoYqgQwbXioWRwmTxsXU=; b=Z/8hcUNmY3chnTqVZEp+xsaD/2h8dIELhPbcV6A3pLr/S/Sc3CdmSvwYPP2GwW5cofyMAQ wLclC/JWmmvOZq02gqf8YQYT8tpoD3R6NP8tcCugjQQ9zik7e8bZJMnzE1PZRoeXmxTHMZ APRN6dNdBNnInqV5WO27H81/U0hoC4I= 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-245-JCqP3r1lPumGoWAVNqfxIw-1; Tue, 19 Oct 2021 15:01:17 -0400 X-MC-Unique: JCqP3r1lPumGoWAVNqfxIw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 31D42800482; Tue, 19 Oct 2021 19:01:12 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id EB0645D6D7; Tue, 19 Oct 2021 19:00:49 +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: References: <163456861570.2614702.14754548462706508617.stgit@warthog.procyon.org.uk> To: Jeff Layton Cc: dhowells@redhat.com, linux-cachefs@redhat.com, ceph-devel@vger.kernel.org, linux-afs@lists.infradead.org, Anna Schumaker , linux-nfs@vger.kernel.org, Kent Overstreet , linux-mm@kvack.org, Matthew Wilcox , linux-fsdevel@vger.kernel.org, Dave Wysochanski , Marc Dionne , Trond Myklebust , Shyam Prasad N , Eric Van Hensbergen , v9fs-developer@lists.sourceforge.net, linux-cifs@vger.kernel.org, Latchesar Ionkov , Steve French , Al Viro , Dominique Martinet , Ilya Dryomov , Trond Myklebust , Omar Sandoval , Linus Torvalds , linux-kernel@vger.kernel.org Subject: Re: [PATCH 00/67] fscache: Rewrite index API and management system MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2972093.1634670049.1@warthog.procyon.org.uk> Date: Tue, 19 Oct 2021 20:00:49 +0100 Message-ID: <2972094.1634670049@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Jeff Layton wrote: > Given the indexing changes, what sort of behavior should we expect when > upgrading from old-style to new-style indexes? Do they just not match, > and we end up downloading new copies of all the data and the old stale > stuff eventually gets culled? Correct: they don't match. The names of the directories and files will be quite different - and so will the attached xattrs. However, no filesystems currently store locally-modified data in the cache, so you shouldn't lose any data after upgrading. > Ditto for downgrades -- can we expect sane behavior if someone runs an > old kernel on top of an existing fscache that was populated by a new > kernel? Correct. With this branch, filesystems now store locally-modified data into the cache - but they also upload it to the server at the same time. If there's a disagreement between what's in the cache and what's on the server with this branch, the cache is discarded, so simply discarding the cache on a download shouldn't be a problem. It's currently operating as a write-through cache, not a write-back cache. That will change if I get round to implementing disconnected operation, but it's not there yet. David