1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Single, monolithic object support (e.g. AFS directory).
3 *
4 * Copyright (C) 2024 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/export.h>
9#include <linux/fs.h>
10#include <linux/mm.h>
11#include <linux/pagemap.h>
12#include <linux/slab.h>
13#include <linux/uio.h>
14#include <linux/sched/mm.h>
15#include <linux/task_io_accounting_ops.h>
16#include <linux/netfs.h>
17#include "internal.h"
18
19/**
20 * netfs_single_mark_inode_dirty - Mark a single, monolithic object inode dirty
21 * @inode: The inode to mark
22 *
23 * Mark an inode that contains a single, monolithic object as dirty so that its
24 * writepages op will get called. If set, the SINGLE_NO_UPLOAD flag indicates
25 * that the object will only be written to the cache and not uploaded (e.g. AFS
26 * directory contents).
27 */
28void netfs_single_mark_inode_dirty(struct inode *inode)
29{
30 struct netfs_inode *ictx = netfs_inode(inode);
31 bool cache_only = test_bit(NETFS_ICTX_SINGLE_NO_UPLOAD, &ictx->flags);
32 bool caching = fscache_cookie_enabled(netfs_i_cookie(netfs_inode(inode)));
33
34 if (cache_only && !caching)
35 return;
36
37 mark_inode_dirty(inode);
38
39 if (caching && !(inode->i_state & I_PINNING_NETFS_WB)) {
40 bool need_use = false;
41
42 spin_lock(lock: &inode->i_lock);
43 if (!(inode->i_state & I_PINNING_NETFS_WB)) {
44 inode->i_state |= I_PINNING_NETFS_WB;
45 need_use = true;
46 }
47 spin_unlock(lock: &inode->i_lock);
48
49 if (need_use)
50 fscache_use_cookie(cookie: netfs_i_cookie(ctx: ictx), will_modify: true);
51 }
52
53}
54EXPORT_SYMBOL(netfs_single_mark_inode_dirty);
55
56static int netfs_single_begin_cache_read(struct netfs_io_request *rreq, struct netfs_inode *ctx)
57{
58 return fscache_begin_read_operation(cres: &rreq->cache_resources, cookie: netfs_i_cookie(ctx));
59}
60
61static void netfs_single_cache_prepare_read(struct netfs_io_request *rreq,
62 struct netfs_io_subrequest *subreq)
63{
64 struct netfs_cache_resources *cres = &rreq->cache_resources;
65
66 if (!cres->ops) {
67 subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
68 return;
69 }
70 subreq->source = cres->ops->prepare_read(subreq, rreq->i_size);
71 trace_netfs_sreq(sreq: subreq, what: netfs_sreq_trace_prepare);
72
73}
74
75static void netfs_single_read_cache(struct netfs_io_request *rreq,
76 struct netfs_io_subrequest *subreq)
77{
78 struct netfs_cache_resources *cres = &rreq->cache_resources;
79
80 _enter("R=%08x[%x]", rreq->debug_id, subreq->debug_index);
81 netfs_stat(&netfs_n_rh_read);
82 cres->ops->read(cres, subreq->start, &subreq->io_iter, NETFS_READ_HOLE_FAIL,
83 netfs_cache_read_terminated, subreq);
84}
85
86/*
87 * Perform a read to a buffer from the cache or the server. Only a single
88 * subreq is permitted as the object must be fetched in a single transaction.
89 */
90static int netfs_single_dispatch_read(struct netfs_io_request *rreq)
91{
92 struct netfs_io_stream *stream = &rreq->io_streams[0];
93 struct netfs_io_subrequest *subreq;
94 int ret = 0;
95
96 subreq = netfs_alloc_subrequest(rreq);
97 if (!subreq)
98 return -ENOMEM;
99
100 subreq->source = NETFS_SOURCE_UNKNOWN;
101 subreq->start = 0;
102 subreq->len = rreq->len;
103 subreq->io_iter = rreq->buffer.iter;
104
105 __set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags);
106
107 spin_lock(lock: &rreq->lock);
108 list_add_tail(new: &subreq->rreq_link, head: &stream->subrequests);
109 trace_netfs_sreq(sreq: subreq, what: netfs_sreq_trace_added);
110 stream->front = subreq;
111 /* Store list pointers before active flag */
112 smp_store_release(&stream->active, true);
113 spin_unlock(lock: &rreq->lock);
114
115 netfs_single_cache_prepare_read(rreq, subreq);
116 switch (subreq->source) {
117 case NETFS_DOWNLOAD_FROM_SERVER:
118 netfs_stat(&netfs_n_rh_download);
119 if (rreq->netfs_ops->prepare_read) {
120 ret = rreq->netfs_ops->prepare_read(subreq);
121 if (ret < 0)
122 goto cancel;
123 }
124
125 rreq->netfs_ops->issue_read(subreq);
126 rreq->submitted += subreq->len;
127 break;
128 case NETFS_READ_FROM_CACHE:
129 trace_netfs_sreq(sreq: subreq, what: netfs_sreq_trace_submit);
130 netfs_single_read_cache(rreq, subreq);
131 rreq->submitted += subreq->len;
132 ret = 0;
133 break;
134 default:
135 pr_warn("Unexpected single-read source %u\n", subreq->source);
136 WARN_ON_ONCE(true);
137 ret = -EIO;
138 break;
139 }
140
141 smp_wmb(); /* Write lists before ALL_QUEUED. */
142 set_bit(NETFS_RREQ_ALL_QUEUED, addr: &rreq->flags);
143 return ret;
144cancel:
145 netfs_put_subrequest(subreq, what: netfs_sreq_trace_put_cancel);
146 return ret;
147}
148
149/**
150 * netfs_read_single - Synchronously read a single blob of pages.
151 * @inode: The inode to read from.
152 * @file: The file we're using to read or NULL.
153 * @iter: The buffer we're reading into.
154 *
155 * Fulfil a read request for a single monolithic object by drawing data from
156 * the cache if possible, or the netfs if not. The buffer may be larger than
157 * the file content; unused beyond the EOF will be zero-filled. The content
158 * will be read with a single I/O request (though this may be retried).
159 *
160 * The calling netfs must initialise a netfs context contiguous to the vfs
161 * inode before calling this.
162 *
163 * This is usable whether or not caching is enabled. If caching is enabled,
164 * the data will be stored as a single object into the cache.
165 */
166ssize_t netfs_read_single(struct inode *inode, struct file *file, struct iov_iter *iter)
167{
168 struct netfs_io_request *rreq;
169 struct netfs_inode *ictx = netfs_inode(inode);
170 ssize_t ret;
171
172 rreq = netfs_alloc_request(mapping: inode->i_mapping, file, start: 0, len: iov_iter_count(i: iter),
173 origin: NETFS_READ_SINGLE);
174 if (IS_ERR(ptr: rreq))
175 return PTR_ERR(ptr: rreq);
176
177 ret = netfs_single_begin_cache_read(rreq, ctx: ictx);
178 if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
179 goto cleanup_free;
180
181 netfs_stat(&netfs_n_rh_read_single);
182 trace_netfs_read(rreq, start: 0, len: rreq->len, what: netfs_read_trace_read_single);
183
184 rreq->buffer.iter = *iter;
185 netfs_single_dispatch_read(rreq);
186
187 ret = netfs_wait_for_read(rreq);
188 netfs_put_request(rreq, what: netfs_rreq_trace_put_return);
189 return ret;
190
191cleanup_free:
192 netfs_put_failed_request(rreq);
193 return ret;
194}
195EXPORT_SYMBOL(netfs_read_single);
196