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 5EC1CC433EF for ; Thu, 31 Mar 2022 11:59:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235526AbiCaMA5 (ORCPT ); Thu, 31 Mar 2022 08:00:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45390 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235471AbiCaMAW (ORCPT ); Thu, 31 Mar 2022 08:00:22 -0400 Received: from out30-57.freemail.mail.aliyun.com (out30-57.freemail.mail.aliyun.com [115.124.30.57]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F07066156; Thu, 31 Mar 2022 04:58:16 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04423;MF=jefflexu@linux.alibaba.com;NM=1;PH=DS;RN=18;SR=0;TI=SMTPD_---0V8imrtn_1648727892; Received: from localhost(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0V8imrtn_1648727892) by smtp.aliyun-inc.com(127.0.0.1); Thu, 31 Mar 2022 19:58:12 +0800 From: Jeffle Xu To: dhowells@redhat.com, linux-cachefs@redhat.com, xiang@kernel.org, chao@kernel.org, linux-erofs@lists.ozlabs.org Cc: torvalds@linux-foundation.org, gregkh@linuxfoundation.org, willy@infradead.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, luodaowen.backend@bytedance.com, tianzichen@kuaishou.com, fannaihao@baidu.com Subject: [PATCH v7 12/19] erofs: add erofs_fscache_read_folios() helper Date: Thu, 31 Mar 2022 19:57:46 +0800 Message-Id: <20220331115753.89431-13-jefflexu@linux.alibaba.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20220331115753.89431-1-jefflexu@linux.alibaba.com> References: <20220331115753.89431-1-jefflexu@linux.alibaba.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add erofs_fscache_read_folios() helper reading from fscache. It supports on-demand read semantics. That is, it will make the backend prepare for the data when cache miss. Once data ready, it will reinitiate a read from the cache. This helper can then be used to implement .readpage()/.readahead() of on-demand read semantics. Signed-off-by: Jeffle Xu --- fs/erofs/fscache.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c index 1c88614203d2..d38a6efc8e50 100644 --- a/fs/erofs/fscache.c +++ b/fs/erofs/fscache.c @@ -5,6 +5,35 @@ #include #include "internal.h" +/* + * Read data from fscache and fill the read data into page cache described by + * @start/len, which shall be both aligned with PAGE_SIZE. @pstart describes + * the start physical address in the cache file. + */ +static int erofs_fscache_read_folios(struct fscache_cookie *cookie, + struct address_space *mapping, + loff_t start, size_t len, + loff_t pstart) +{ + struct netfs_cache_resources cres; + struct iov_iter iter; + int ret; + + memset(&cres, 0, sizeof(cres)); + + ret = fscache_begin_read_operation(&cres, cookie); + if (ret) + return ret; + + iov_iter_xarray(&iter, READ, &mapping->i_pages, start, len); + + ret = fscache_read(&cres, pstart, &iter, + NETFS_READ_HOLE_ONDEMAND, NULL, NULL); + + fscache_end_operation(&cres); + return ret; +} + static const struct address_space_operations erofs_fscache_meta_aops = { }; -- 2.27.0