From patchwork Mon Dec 27 12:54:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jingbo Xu X-Patchwork-Id: 12699752 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 000FFC4332F for ; Mon, 27 Dec 2021 12:55:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237037AbhL0MzS (ORCPT ); Mon, 27 Dec 2021 07:55:18 -0500 Received: from out30-132.freemail.mail.aliyun.com ([115.124.30.132]:35702 "EHLO out30-132.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236978AbhL0MzM (ORCPT ); Mon, 27 Dec 2021 07:55:12 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=jefflexu@linux.alibaba.com;NM=1;PH=DS;RN=12;SR=0;TI=SMTPD_---0V.xJoSm_1640609709; Received: from localhost(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0V.xJoSm_1640609709) by smtp.aliyun-inc.com(127.0.0.1); Mon, 27 Dec 2021 20:55:10 +0800 From: Jeffle Xu To: dhowells@redhat.com, linux-cachefs@redhat.com, xiang@kernel.org, chao@kernel.org, linux-erofs@lists.ozlabs.org Cc: 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 Subject: [PATCH v1 21/23] cachefiles: implement .read() for demand read Date: Mon, 27 Dec 2021 20:54:42 +0800 Message-Id: <20211227125444.21187-22-jefflexu@linux.alibaba.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20211227125444.21187-1-jefflexu@linux.alibaba.com> References: <20211227125444.21187-1-jefflexu@linux.alibaba.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Once notified, user daemon need to get more details of the request by reading the devnode. The readed information includes the file range of the request, with which user daemon could somehow prepare corresponding data (e.g. download from remote through network) and fill the hole. Signed-off-by: Jeffle Xu --- fs/cachefiles/daemon.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c index 311dcd911a85..ce4cc5617dfc 100644 --- a/fs/cachefiles/daemon.c +++ b/fs/cachefiles/daemon.c @@ -29,6 +29,8 @@ static ssize_t cachefiles_daemon_write(struct file *, const char __user *, size_t, loff_t *); static __poll_t cachefiles_daemon_poll(struct file *, struct poll_table_struct *); +static ssize_t cachefiles_demand_read(struct file *, char __user *, size_t, + loff_t *); static __poll_t cachefiles_demand_poll(struct file *, struct poll_table_struct *); static int cachefiles_daemon_frun(struct cachefiles_cache *, char *); @@ -63,6 +65,7 @@ const struct file_operations cachefiles_demand_fops = { .owner = THIS_MODULE, .open = cachefiles_daemon_open, .release = cachefiles_daemon_release, + .read = cachefiles_demand_read, .write = cachefiles_daemon_write, .poll = cachefiles_demand_poll, .llseek = noop_llseek, @@ -322,6 +325,32 @@ static __poll_t cachefiles_daemon_poll(struct file *file, return mask; } +static ssize_t cachefiles_demand_read(struct file *file, char __user *_buffer, + size_t buflen, loff_t *pos) +{ + struct cachefiles_cache *cache = file->private_data; + struct cachefiles_req *req; + int n, id = 0; + + if (!test_bit(CACHEFILES_READY, &cache->flags)) + return 0; + + spin_lock(&cache->reqs_lock); + req = idr_get_next(&cache->reqs, &id); + spin_unlock(&cache->reqs_lock); + if (!req) + return 0; + + n = sizeof(req->req_in); + if (n > buflen) + return -EMSGSIZE; + + if (copy_to_user(_buffer, &req->req_in, n) != 0) + return -EFAULT; + + return n; +} + static __poll_t cachefiles_demand_poll(struct file *file, struct poll_table_struct *poll) {