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=-5.9 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,URIBL_BLOCKED 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 19BE6C433E0 for ; Thu, 21 Jan 2021 19:19:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E1C3123136 for ; Thu, 21 Jan 2021 19:19:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726643AbhAUTTr (ORCPT ); Thu, 21 Jan 2021 14:19:47 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:45131 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726482AbhAUTI1 (ORCPT ); Thu, 21 Jan 2021 14:08:27 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611256021; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8cQVBtElgHkrZu0TCW+Tp+86juePWkkpr+KAAgOabXU=; b=AxZpqlQJb1pHt5uGjm8luNMnTQZTydxW6KIwP9Ong4xVAVsXwJ3CE5sbgI+V689RuOhQoH HKKT0sV4SMuzK38w8tI3LpI7/epeaBOQwkrquCX/Z3MTL+1KI0m6WnF6tnnGem70hppMcn KAicaTNawAi9iD42dY+QSnQuEVjKl1s= 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-594-ogR02f57MSGANxw_NhZwKQ-1; Thu, 21 Jan 2021 13:55:23 -0500 X-MC-Unique: ogR02f57MSGANxw_NhZwKQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 570368066F2; Thu, 21 Jan 2021 18:55:21 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-115-23.rdu2.redhat.com [10.10.115.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id 810576EF42; Thu, 21 Jan 2021 18:55:14 +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: <20210121174306.GB20964@fieldses.org> References: <20210121174306.GB20964@fieldses.org> <20210121164645.GA20964@fieldses.org> <161118128472.1232039.11746799833066425131.stgit@warthog.procyon.org.uk> <1794286.1611248577@warthog.procyon.org.uk> To: "J. Bruce Fields" Cc: dhowells@redhat.com, Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet , Takashi Iwai , Matthew Wilcox , linux-afs@lists.infradead.org, Jeff Layton , David Wysochanski , Alexander Viro , linux-cachefs@redhat.com, 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: [RFC][PATCH 00/25] Network fs helper library & fscache kiocb API MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <1851803.1611255313.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Thu, 21 Jan 2021 18:55:13 +0000 Message-ID: <1851804.1611255313@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org J. Bruce Fields wrote: > > Fixing this requires a much bigger overhaul of cachefiles than this pa= tchset > > performs. > = > That sounds like "sometimes you may get file corruption and there's > nothing you can do about it". But I know people actually use fscache, > so it must be reliable at least for some use cases. Yes. That's true for the upstream code because that uses bmap. I'm switc= hing to use SEEK_HOLE/SEEK_DATA to get rid of the bmap usage, but it doesn't ch= ange the issue. > Is it that those "bridging" blocks only show up in certain corner cases > that users can arrange to avoid? Or that it's OK as long as you use > certain specific file systems whose behavior goes beyond what's > technically required by the bamp or seek interfaces? That's a question for the xfs, ext4 and btrfs maintainers, and may vary between kernel versions and fsck or filesystem packing utility versions. David