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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C1E83C4332F for ; Thu, 9 Dec 2021 16:50:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237968AbhLIQx5 (ORCPT ); Thu, 9 Dec 2021 11:53:57 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:22437 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241318AbhLIQx5 (ORCPT ); Thu, 9 Dec 2021 11:53:57 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1639068623; 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=J1GcNbc9O5U5G8LlnP/kK4YsVg9drcvikjSXrTjTmMo=; b=XXcMufcf1A33ShGEcu/cIiaLPiMTGL16gdDSZZIBBRLuNK6gCt7C6kbEkAQDdYz2GDVqCt BRYwonIPl1rZj9eQ2SEenlK5PYNAmfteUR14vezEphkjYokNCs/mV95PEaEkrLtju5jwIq XjDFkce+O3/381oebL8x0EgnavuTqfc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-584-JHLalODTOZi6-eTunFrpGg-1; Thu, 09 Dec 2021 11:50:21 -0500 X-MC-Unique: JHLalODTOZi6-eTunFrpGg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 79DE718C89DF; Thu, 9 Dec 2021 16:50:19 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.122]) by smtp.corp.redhat.com (Postfix) with ESMTP id 24DE25ED39; Thu, 9 Dec 2021 16:49:53 +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: <163819575444.215744.318477214576928110.stgit@warthog.procyon.org.uk> <163819612321.215744.9738308885948264476.stgit@warthog.procyon.org.uk> To: JeffleXu Cc: dhowells@redhat.com, linux-cachefs@redhat.com, Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet , Jeff Layton , Matthew Wilcox , Alexander Viro , Omar Sandoval , Linus Torvalds , 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: [PATCH 24/64] netfs: Pass more information on how to deal with a hole in the cache MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <143691.1639068593.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Thu, 09 Dec 2021 16:49:53 +0000 Message-ID: <143692.1639068593@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org JeffleXu wrote: > > @@ -466,7 +466,7 @@ static void netfs_rreq_short_read(struct netfs_rea= d_request *rreq, > > netfs_get_read_subrequest(subreq); > > atomic_inc(&rreq->nr_rd_ops); > > if (subreq->source =3D=3D NETFS_READ_FROM_CACHE) > > - netfs_read_from_cache(rreq, subreq, true); > > + netfs_read_from_cache(rreq, subreq, NETFS_READ_HOLE_CLEAR); > = > Hi I'm not sure why NETFS_READ_HOLE_CLEAR style should be used in 'short > read' case. The cache backing filesystem (eg. ext4) might have excised a chunk of zero= s from the cache in order to optimise its extent list. This instructs the c= ache to zero over the cracks. Actually, I need to think a bit further on this. This was written assuming that the cache tracks its content independently = - but those patches are not in with this set. > I'm not sure why 'subreq->start' is not incremented with > 'subreq->transferred' when calling cres->ops->read() in 'short read' cas= e. subreq->start shouldn't get changed. subreq->transferred is sufficient. David