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 4EEDAC433EF for ; Thu, 27 Jan 2022 07:07:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237104AbiA0HHF (ORCPT ); Thu, 27 Jan 2022 02:07:05 -0500 Received: from out30-57.freemail.mail.aliyun.com ([115.124.30.57]:51914 "EHLO out30-57.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229823AbiA0HHE (ORCPT ); Thu, 27 Jan 2022 02:07:04 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R161e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04407;MF=jefflexu@linux.alibaba.com;NM=1;PH=DS;RN=12;SR=0;TI=SMTPD_---0V2z08g._1643267220; Received: from 30.225.24.48(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0V2z08g._1643267220) by smtp.aliyun-inc.com(127.0.0.1); Thu, 27 Jan 2022 15:07:02 +0800 Message-ID: <8f73d28e-db30-f2e4-0143-9d75c4b13087@linux.alibaba.com> Date: Thu, 27 Jan 2022 15:07:00 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.3.2 Subject: Re: [PATCH v2 00/20] fscache,erofs: fscache-based demand-read semantics Content-Language: en-US To: David Howells Cc: linux-cachefs@redhat.com, xiang@kernel.org, chao@kernel.org, linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, joseph.qi@linux.alibaba.com, bo.liu@linux.alibaba.com, tao.peng@linux.alibaba.com, gerry@linux.alibaba.com, eguan@linux.alibaba.com, linux-kernel@vger.kernel.org References: <8f88459a-97e0-8b8d-3ec9-260d482a0d38@linux.alibaba.com> <20220118131216.85338-1-jefflexu@linux.alibaba.com> <2815558.1643127330@warthog.procyon.org.uk> <100895.1643187095@warthog.procyon.org.uk> From: JeffleXu In-Reply-To: <100895.1643187095@warthog.procyon.org.uk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 1/26/22 4:51 PM, David Howells wrote: > JeffleXu wrote: > >> "/path/to/file+offset" >> ^ >> >> Besides, what does the 'offset' mean? > > Assuming you're storing multiple erofs files within the same backend file, you > need to tell the the cache backend how to find the data. Assuming the erofs > data is arranged such that each erofs file is a single contiguous region, then > you need a pathname and a file offset to find one of them. > Alright. In fact one erofs file can contain multiple chunks, which can correspond to different backing blob files. Thus currently I will use fscache_read() directly, to push this feature forward. Thanks a lot. -- Thanks, Jeffle