From patchwork Fri Mar 25 12:22:06 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jingbo Xu X-Patchwork-Id: 12791540 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 89350C433EF for ; Fri, 25 Mar 2022 12:22:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358978AbiCYMYP (ORCPT ); Fri, 25 Mar 2022 08:24:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38340 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354835AbiCYMYM (ORCPT ); Fri, 25 Mar 2022 08:24:12 -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 17B0ED4CBE; Fri, 25 Mar 2022 05:22:37 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R171e4;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_---0V89zY1L_1648210951; Received: from localhost(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0V89zY1L_1648210951) by smtp.aliyun-inc.com(127.0.0.1); Fri, 25 Mar 2022 20:22:32 +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 v6 05/22] cachefiles: implement on-demand read Date: Fri, 25 Mar 2022 20:22:06 +0800 Message-Id: <20220325122223.102958-6-jefflexu@linux.alibaba.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20220325122223.102958-1-jefflexu@linux.alibaba.com> References: <20220325122223.102958-1-jefflexu@linux.alibaba.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Implement the data plane of on-demand read mode. A new NETFS_READ_HOLE_ONDEMAND flag is introduced to indicate that on-demand read should be done when a cache miss encountered. In this case, the read routine will send a READ request to user daemon, along with the anonymous fd and the file range that shall be read. Now user daemon is responsible for fetching data in the given file range, and then writing the fetched data into cache file with the given anonymous fd. After sending the READ request, the read routine will hang there, until the READ request is handled by user daemon. Then it will retry to read from the same file range. If a cache miss is encountered again on the same file range, the read routine will fail then. Signed-off-by: Jeffle Xu --- fs/cachefiles/internal.h | 7 +++ fs/cachefiles/io.c | 11 +++++ fs/cachefiles/ondemand.c | 81 +++++++++++++++++++++++++++++++++ include/linux/netfs.h | 1 + include/uapi/linux/cachefiles.h | 13 ++++++ 5 files changed, 113 insertions(+) diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index c80b519a887b..686f25097681 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -281,6 +281,8 @@ extern int cachefiles_ondemand_cinit(struct cachefiles_cache *cache, extern int cachefiles_ondemand_init_object(struct cachefiles_object *object); extern void cachefiles_ondemand_cleanup_object(struct cachefiles_object *object); +extern int cachefiles_ondemand_read(struct cachefiles_object *object, + loff_t pos, size_t len); #else ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache, @@ -295,6 +297,11 @@ static inline int cachefiles_ondemand_init_object(struct cachefiles_object *obje } static inline void cachefiles_ondemand_cleanup_object(struct cachefiles_object *object) {} +static inline int cachefiles_ondemand_read(struct cachefiles_object *object, + loff_t pos, size_t len) +{ + return -EOPNOTSUPP; +} #endif /* diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c index 8dbc1eb254a3..ee1283ba7a2c 100644 --- a/fs/cachefiles/io.c +++ b/fs/cachefiles/io.c @@ -95,6 +95,7 @@ static int cachefiles_read(struct netfs_cache_resources *cres, file, file_inode(file)->i_ino, start_pos, len, i_size_read(file_inode(file))); +retry: /* If the caller asked us to seek for data before doing the read, then * we should do that now. If we find a gap, we fill it with zeros. */ @@ -119,6 +120,16 @@ static int cachefiles_read(struct netfs_cache_resources *cres, if (read_hole == NETFS_READ_HOLE_FAIL) goto presubmission_error; + if (read_hole == NETFS_READ_HOLE_ONDEMAND) { + if (!cachefiles_ondemand_read(object, off, len)) { + /* fail the read if no progress achieved */ + read_hole = NETFS_READ_HOLE_FAIL; + goto retry; + } + + goto presubmission_error; + } + iov_iter_zero(len, iter); skipped = len; ret = 0; diff --git a/fs/cachefiles/ondemand.c b/fs/cachefiles/ondemand.c index 7fd518e01e5a..965fb7bd97c0 100644 --- a/fs/cachefiles/ondemand.c +++ b/fs/cachefiles/ondemand.c @@ -11,13 +11,30 @@ static int cachefiles_ondemand_fd_release(struct inode *inode, struct file *file) { struct cachefiles_object *object = file->private_data; + struct cachefiles_cache *cache = object->volume->cache; + struct xarray *xa = &cache->reqs; + struct cachefiles_req *req; + unsigned long index; + xa_lock(xa); /* * Uninstall anon_fd to the cachefiles object, so that no further * associated requests will get enqueued. */ object->fd = -1; + /* + * Flush all pending READ requests since their completion depends on + * anon_fd. + */ + xa_for_each(xa, index, req) { + if (req->msg.opcode == CACHEFILES_OP_READ) { + req->error = -EIO; + complete(&req->done); + } + } + xa_unlock(xa); + cachefiles_put_object(object, cachefiles_obj_put_ondemand_fd); return 0; } @@ -60,11 +77,35 @@ static loff_t cachefiles_ondemand_fd_llseek(struct file *filp, loff_t pos, int w return vfs_llseek(file, pos, whence); } +static long cachefiles_ondemand_fd_ioctl(struct file *filp, unsigned int ioctl, + unsigned long arg) +{ + struct cachefiles_object *object = filp->private_data; + struct cachefiles_cache *cache = object->volume->cache; + struct cachefiles_req *req; + unsigned long id; + + if (ioctl != CACHEFILES_IOC_CREAD) + return -EINVAL; + + if (!test_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags)) + return -EOPNOTSUPP; + + id = arg; + req = xa_erase(&cache->reqs, id); + if (!req) + return -EINVAL; + + complete(&req->done); + return 0; +} + static const struct file_operations cachefiles_ondemand_fd_fops = { .owner = THIS_MODULE, .release = cachefiles_ondemand_fd_release, .write_iter = cachefiles_ondemand_fd_write_iter, .llseek = cachefiles_ondemand_fd_llseek, + .unlocked_ioctl = cachefiles_ondemand_fd_ioctl, }; /* @@ -269,6 +310,13 @@ static int cachefiles_ondemand_send_req(struct cachefiles_object *object, goto out; } + /* recheck anon_fd for READ request with lock held */ + if (opcode == CACHEFILES_OP_READ && object->fd == -1) { + xas_unlock(&xas); + ret = -EIO; + goto out; + } + xas.xa_index = 0; xas_find_marked(&xas, UINT_MAX, XA_FREE_MARK); if (xas.xa_node == XAS_RESTART) @@ -341,6 +389,28 @@ static int init_close_req(struct cachefiles_req *req, void *private) return 0; } +struct cachefiles_read_ctx { + loff_t off; + size_t len; +}; + +static int init_read_req(struct cachefiles_req *req, void *private) +{ + struct cachefiles_object *object = req->object; + struct cachefiles_read *load = (void *)&req->msg.data; + struct cachefiles_read_ctx *read_ctx = private; + int fd = object->fd; + + /* Stop enqueuing request when daemon closes anon_fd prematurely. */ + if (WARN_ON_ONCE(fd == -1)) + return -EIO; + + load->off = read_ctx->off; + load->len = read_ctx->len; + load->fd = fd; + return 0; +} + int cachefiles_ondemand_init_object(struct cachefiles_object *object) { struct fscache_cookie *cookie = object->cookie; @@ -373,3 +443,14 @@ void cachefiles_ondemand_cleanup_object(struct cachefiles_object *object) sizeof(struct cachefiles_close), init_close_req, NULL); } + +int cachefiles_ondemand_read(struct cachefiles_object *object, + loff_t pos, size_t len) +{ + struct cachefiles_read_ctx read_ctx = {pos, len}; + + return cachefiles_ondemand_send_req(object, + CACHEFILES_OP_READ, + sizeof(struct cachefiles_read), + init_read_req, &read_ctx); +} diff --git a/include/linux/netfs.h b/include/linux/netfs.h index 614f22213e21..2a9c50d3a928 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -203,6 +203,7 @@ enum netfs_read_from_hole { NETFS_READ_HOLE_IGNORE, NETFS_READ_HOLE_CLEAR, NETFS_READ_HOLE_FAIL, + NETFS_READ_HOLE_ONDEMAND, }; /* diff --git a/include/uapi/linux/cachefiles.h b/include/uapi/linux/cachefiles.h index 03047e4b7df2..004335d44e16 100644 --- a/include/uapi/linux/cachefiles.h +++ b/include/uapi/linux/cachefiles.h @@ -3,6 +3,7 @@ #define _LINUX_CACHEFILES_H #include +#include /* * Fscache ensures that the maximum length of cookie key is 255. The volume key @@ -13,6 +14,7 @@ enum cachefiles_opcode { CACHEFILES_OP_OPEN, CACHEFILES_OP_CLOSE, + CACHEFILES_OP_READ, }; /* @@ -45,4 +47,15 @@ struct cachefiles_close { __u32 fd; }; +struct cachefiles_read { + __u64 off; + __u64 len; + __u32 fd; +}; + +/* + * For CACHEFILES_IOC_CREAD, arg is the @id field of corresponding READ request. + */ +#define CACHEFILES_IOC_CREAD _IOW(0x98, 1, long) + #endif