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 50BC7C433F5 for ; Fri, 22 Oct 2021 18:52:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3AD2260F5D for ; Fri, 22 Oct 2021 18:52:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232375AbhJVSy4 (ORCPT ); Fri, 22 Oct 2021 14:54:56 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:56832 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229463AbhJVSyy (ORCPT ); Fri, 22 Oct 2021 14:54:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634928756; 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=tW1THt74zlEe0JuUHAuc3WzNTwwNynQeKBO1wEGMPGk=; b=dQk+JBqP/CI2oRGIKyMOwoWWK+URmJ2cIxoELexdxuLa1iFv3A73M3zPNbbb9eiPfOmJfW pZJ61HMEPlVJXbqnfKFGZt/DIAFLBUycggTZsgoccs+RKO9v6Eth9t93Lp0+P1NGAqap88 rHRQHY7qNWoP7unMtyGAfTuq7M6pVwA= 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-339-LwTXxwRMMRqR8zd0PjpeHQ-1; Fri, 22 Oct 2021 14:52:31 -0400 X-MC-Unique: LwTXxwRMMRqR8zd0PjpeHQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3DAC8802B4F; Fri, 22 Oct 2021 18:52:28 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id CA62C60C04; Fri, 22 Oct 2021 18:52:19 +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: Steve French Cc: David Howells , Omar Sandoval , Anna Schumaker , Kent Overstreet , Matthew Wilcox , Dave Wysochanski , Marc Dionne , Trond Myklebust , Shyam Prasad N , Eric Van Hensbergen , Latchesar Ionkov , Jeff Layton , Steve French , Al Viro , Dominique Martinet , Ilya Dryomov , Trond Myklebust , Jeff Layton , Linus Torvalds , linux-cachefs@redhat.com, v9fs-developer@lists.sourceforge.net, linux-afs@lists.infradead.org, ceph-devel , CIFS , linux-nfs , linux-mm , linux-fsdevel , LKML 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: <1037423.1634928738.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Fri, 22 Oct 2021 19:52:18 +0100 Message-ID: <1037424.1634928738@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Steve French wrote: > On Thu, Oct 21, 2021 at 5:21 PM Omar Sandoval wrot= e: > > > > On Mon, Oct 18, 2021 at 03:50:15PM +0100, David Howells wrote: > > However, with the advent of the tmpfile capacity in the VFS, an opport= unity > > arises to do invalidation much more easily, without having to wait for= I/O > > that's actually in progress: Cachefiles can simply cut over its file > > pointer for the backing object attached to a cookie and abandon the > > in-progress I/O, dismissing it upon completion. > = > Have changes been made to O_TMPFILE? It is problematic for network > filesystems because it is not an atomic operation, and would be great if= it > were possible to create a tmpfile and open it atomically (at the file sy= stem > level). In this case, it's nothing to do with the network filesystem that's using = the cache per se. Cachefiles is using tmpfiles on the backing filesystem, so = as long as that's, say, ext4, xfs or btrfs, it should work fine. The backing filesystem also needs to support SEEK_HOLE and SEEK_DATA. I'm not sure I'd recommend putting your cache on a network filesystem. David