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 7B8D5C4321E for ; Tue, 29 Nov 2022 11:59:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231326AbiK2L7G (ORCPT ); Tue, 29 Nov 2022 06:59:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59298 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229900AbiK2L6j (ORCPT ); Tue, 29 Nov 2022 06:58:39 -0500 Received: from out30-6.freemail.mail.aliyun.com (out30-6.freemail.mail.aliyun.com [115.124.30.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DB54C65CC for ; Tue, 29 Nov 2022 03:58:37 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R511e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045192;MF=jefflexu@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0VW-kQll_1669723113; Received: from localhost(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0VW-kQll_1669723113) by smtp.aliyun-inc.com; Tue, 29 Nov 2022 19:58:34 +0800 From: Jingbo Xu To: xiang@kernel.org, chao@kernel.org, linux-erofs@lists.ozlabs.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH v3 0/2] erofs: support large folios for fscache mode Date: Tue, 29 Nov 2022 19:58:31 +0800 Message-Id: <20221129115833.41062-1-jefflexu@linux.alibaba.com> X-Mailer: git-send-email 2.19.1.6.gb485710b MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org v3: - patch 1: when large folios supported, one folio or folio range can be mapped into several slices, with each slice mapped to different cookies, and thus each slice needs its own netfs_cache_resources. In the implementation of v2, each .read_folio() or .readahead() calling corresponds to only one request, and thus only one netfs_cache_resources (embedded in the request). In this case, fscache_begin_read_operation() may be called multiple times on this cres, while cres->ops->end_operation() is called only once when the whole request completes. This can cause the leakage of the corresponding cachefiles_object->n_accesses refcount, which will cause the user daemon hangs there forever waiting for cache->object_count decreasing to 0 when the user daemon exits. Worsely, as we mentioned previously, when large folios supported, one folio or folio range can be mapped to multiple chunks on different cookies, in which case each mapped chunk needs its own cres. In the implementation of v2, each .read_folio() or .readahead() calling corresponds to only one request, and thus only one cres. This will make the only cres used by the first chunk gets overridden by the following chunk. To fix this, we introduce listed requests, where each .read_folio() or .readahead() calling can correspond to a list of requests, with each request corresponds to one cres. v2: https://lore.kernel.org/all/20221128025011.36352-1-jefflexu@linux.alibaba.com/ v1: https://lore.kernel.org/all/20221126005756.7662-1-jefflexu@linux.alibaba.com/ v2: - patch 2: keep the enabling for iomap and fscache mode in separate patches; don't enable the feature for the meta data routine for now (Gao Xiang) Patch 1 is the main part of supporting large folios for fscache mode. It relies on a pending patch[1] adding .prepare_ondemand_read() interface in Cachefiles. Patch 2 just turns the switch on and enables the feature for fscache mode. It relies on a previous patch[2] which enables this feature for iomap mode. [1] https://lore.kernel.org/all/20221124034212.81892-1-jefflexu@linux.alibaba.com/ [2] https://lore.kernel.org/all/20221110074023.8059-1-jefflexu@linux.alibaba.com/ Jingbo Xu (2): erofs: support large folios for fscache mode erofs: enable large folios for fscache mode fs/erofs/fscache.c | 166 ++++++++++++++++++++++++--------------------- fs/erofs/inode.c | 3 +- 2 files changed, 89 insertions(+), 80 deletions(-) -- 2.19.1.6.gb485710b