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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EBD54C433F5 for ; Wed, 9 Feb 2022 06:06:42 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4JtqC51zPTz3bPM for ; Wed, 9 Feb 2022 17:06:41 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.alibaba.com (client-ip=47.90.199.14; helo=out199-14.us.a.mail.aliyun.com; envelope-from=jefflexu@linux.alibaba.com; receiver=) Received: from out199-14.us.a.mail.aliyun.com (out199-14.us.a.mail.aliyun.com [47.90.199.14]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4JtqC23LLfz2x9Q for ; Wed, 9 Feb 2022 17:06:38 +1100 (AEDT) X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R701e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e04357; MF=jefflexu@linux.alibaba.com; NM=1; PH=DS; RN=15; SR=0; TI=SMTPD_---0V3zaQT8_1644386484; Received: from localhost(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0V3zaQT8_1644386484) by smtp.aliyun-inc.com(127.0.0.1); Wed, 09 Feb 2022 14:01:25 +0800 From: Jeffle Xu To: dhowells@redhat.com, linux-cachefs@redhat.com, xiang@kernel.org, chao@kernel.org, linux-erofs@lists.ozlabs.org Subject: [PATCH v3 12/22] erofs: add erofs_fscache_read_page() helper Date: Wed, 9 Feb 2022 14:00:58 +0800 Message-Id: <20220209060108.43051-13-jefflexu@linux.alibaba.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20220209060108.43051-1-jefflexu@linux.alibaba.com> References: <20220209060108.43051-1-jefflexu@linux.alibaba.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linux-erofs@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development of Linux EROFS file system List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: gregkh@linuxfoundation.org, willy@infradead.org, linux-kernel@vger.kernel.org, joseph.qi@linux.alibaba.com, linux-fsdevel@vger.kernel.org, gerry@linux.alibaba.com, torvalds@linux-foundation.org Errors-To: linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Sender: "Linux-erofs" Add erofs_fscache_read_page() 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() of on-demand reading semantics. Signed-off-by: Jeffle Xu --- fs/erofs/fscache.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c index 3addd9aa549c..f4aade711664 100644 --- a/fs/erofs/fscache.c +++ b/fs/erofs/fscache.c @@ -6,6 +6,42 @@ static struct fscache_volume *volume; +static int erofs_fscache_read_page(struct fscache_cookie *cookie, + struct page *page, loff_t start_pos) +{ + struct netfs_cache_resources cres; + struct bio_vec bvec[1]; + struct iov_iter iter; + int ret; + + memset(&cres, 0, sizeof(cres)); + + ret = fscache_begin_read_operation(&cres, cookie); + if (ret) + return ret; + + bvec[0].bv_page = page; + bvec[0].bv_offset = 0; + bvec[0].bv_len = PAGE_SIZE; + iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE); + + ret = fscache_read(&cres, start_pos, &iter, + NETFS_READ_HOLE_FAIL, NULL, NULL); + /* + * -ENODATA will be returned when cache miss. In this case, make the + * backend prepare for the data and then reinitiate a read from cache. + */ + if (ret == -ENODATA) { + ret = fscache_ondemand_read(&cres, start_pos, PAGE_SIZE); + if (ret == 0) + ret = fscache_read(&cres, start_pos, &iter, + NETFS_READ_HOLE_FAIL, NULL, NULL); + } + + fscache_end_operation(&cres); + return ret; +} + static const struct address_space_operations erofs_fscache_blob_aops = { }; -- 2.27.0