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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* handling of writes to regular files and writing back to the server
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells ([email protected])
6 */
7
8#include <linux/backing-dev.h>
9#include <linux/slab.h>
10#include <linux/fs.h>
11#include <linux/pagemap.h>
12#include <linux/writeback.h>
13#include <linux/netfs.h>
14#include <trace/events/netfs.h>
15#include "internal.h"
16
17/*
18 * completion of write to server
19 */
20static void afs_pages_written_back(struct afs_vnode *vnode, loff_t start, unsigned int len)
21{
22 _enter("{%llx:%llu},{%x @%llx}",
23 vnode->fid.vid, vnode->fid.vnode, len, start);
24
25 afs_prune_wb_keys(vnode);
26 _leave("");
27}
28
29/*
30 * Find a key to use for the writeback. We cached the keys used to author the
31 * writes on the vnode. wreq->netfs_priv2 will contain the last writeback key
32 * record used or NULL and we need to start from there if it's set.
33 * wreq->netfs_priv will be set to the key itself or NULL.
34 */
35static void afs_get_writeback_key(struct netfs_io_request *wreq)
36{
37 struct afs_wb_key *wbk, *old = wreq->netfs_priv2;
38 struct afs_vnode *vnode = AFS_FS_I(wreq->inode);
39
40 key_put(wreq->netfs_priv);
41 wreq->netfs_priv = NULL;
42 wreq->netfs_priv2 = NULL;
43
44 spin_lock(&vnode->wb_lock);
45 if (old)
46 wbk = list_next_entry(old, vnode_link);
47 else
48 wbk = list_first_entry(&vnode->wb_keys, struct afs_wb_key, vnode_link);
49
50 list_for_each_entry_from(wbk, &vnode->wb_keys, vnode_link) {
51 _debug("wbk %u", key_serial(wbk->key));
52 if (key_validate(wbk->key) == 0) {
53 refcount_inc(&wbk->usage);
54 wreq->netfs_priv = key_get(wbk->key);
55 wreq->netfs_priv2 = wbk;
56 _debug("USE WB KEY %u", key_serial(wbk->key));
57 break;
58 }
59 }
60
61 spin_unlock(&vnode->wb_lock);
62
63 afs_put_wb_key(old);
64}
65
66static void afs_store_data_success(struct afs_operation *op)
67{
68 struct afs_vnode *vnode = op->file[0].vnode;
69
70 op->ctime = op->file[0].scb.status.mtime_client;
71 afs_vnode_commit_status(op, &op->file[0]);
72 if (!afs_op_error(op)) {
73 afs_pages_written_back(vnode, op->store.pos, op->store.size);
74 afs_stat_v(vnode, n_stores);
75 atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes);
76 }
77}
78
79static const struct afs_operation_ops afs_store_data_operation = {
80 .issue_afs_rpc = afs_fs_store_data,
81 .issue_yfs_rpc = yfs_fs_store_data,
82 .success = afs_store_data_success,
83};
84
85/*
86 * Prepare a subrequest to write to the server. This sets the max_len
87 * parameter.
88 */
89void afs_prepare_write(struct netfs_io_subrequest *subreq)
90{
91 struct netfs_io_stream *stream = &subreq->rreq->io_streams[subreq->stream_nr];
92
93 //if (test_bit(NETFS_SREQ_RETRYING, &subreq->flags))
94 // subreq->max_len = 512 * 1024;
95 //else
96 stream->sreq_max_len = 256 * 1024 * 1024;
97}
98
99/*
100 * Issue a subrequest to write to the server.
101 */
102static void afs_issue_write_worker(struct work_struct *work)
103{
104 struct netfs_io_subrequest *subreq = container_of(work, struct netfs_io_subrequest, work);
105 struct netfs_io_request *wreq = subreq->rreq;
106 struct afs_operation *op;
107 struct afs_vnode *vnode = AFS_FS_I(wreq->inode);
108 unsigned long long pos = subreq->start + subreq->transferred;
109 size_t len = subreq->len - subreq->transferred;
110 int ret = -ENOKEY;
111
112 _enter("R=%x[%x],%s{%llx:%llu.%u},%llx,%zx",
113 wreq->debug_id, subreq->debug_index,
114 vnode->volume->name,
115 vnode->fid.vid,
116 vnode->fid.vnode,
117 vnode->fid.unique,
118 pos, len);
119
120#if 0 // Error injection
121 if (subreq->debug_index == 3)
122 return netfs_write_subrequest_terminated(subreq, -ENOANO);
123
124 if (!subreq->retry_count) {
125 set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
126 return netfs_write_subrequest_terminated(subreq, -EAGAIN);
127 }
128#endif
129
130 op = afs_alloc_operation(wreq->netfs_priv, vnode->volume);
131 if (IS_ERR(op))
132 return netfs_write_subrequest_terminated(subreq, -EAGAIN);
133
134 afs_op_set_vnode(op, 0, vnode);
135 op->file[0].dv_delta = 1;
136 op->file[0].modification = true;
137 op->store.pos = pos;
138 op->store.size = len;
139 op->flags |= AFS_OPERATION_UNINTR;
140 op->ops = &afs_store_data_operation;
141
142 afs_begin_vnode_operation(op);
143
144 op->store.write_iter = &subreq->io_iter;
145 op->store.i_size = umax(pos + len, netfs_read_remote_i_size(&vnode->netfs.inode));
146 op->mtime = inode_get_mtime(&vnode->netfs.inode);
147
148 afs_wait_for_operation(op);
149 ret = afs_put_operation(op);
150 switch (ret) {
151 case 0:
152 __set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
153 break;
154 case -EACCES:
155 case -EPERM:
156 case -ENOKEY:
157 case -EKEYEXPIRED:
158 case -EKEYREJECTED:
159 case -EKEYREVOKED:
160 /* If there are more keys we can try, use the retry algorithm
161 * to rotate the keys.
162 */
163 if (wreq->netfs_priv2)
164 set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
165 break;
166 }
167
168 netfs_write_subrequest_terminated(subreq, ret < 0 ? ret : subreq->len);
169}
170
171void afs_issue_write(struct netfs_io_subrequest *subreq)
172{
173 subreq->work.func = afs_issue_write_worker;
174 if (!queue_work(system_dfl_wq, &subreq->work))
175 WARN_ON_ONCE(1);
176}
177
178/*
179 * Writeback calls this when it finds a folio that needs uploading. This isn't
180 * called if writeback only has copy-to-cache to deal with.
181 */
182void afs_begin_writeback(struct netfs_io_request *wreq)
183{
184 if (S_ISREG(wreq->inode->i_mode))
185 afs_get_writeback_key(wreq);
186}
187
188/*
189 * Prepare to retry the writes in request. Use this to try rotating the
190 * available writeback keys.
191 */
192void afs_retry_request(struct netfs_io_request *wreq, struct netfs_io_stream *stream)
193{
194 struct netfs_io_subrequest *subreq =
195 list_first_entry(&stream->subrequests,
196 struct netfs_io_subrequest, rreq_link);
197
198 switch (wreq->origin) {
199 case NETFS_READAHEAD:
200 case NETFS_READPAGE:
201 case NETFS_READ_GAPS:
202 case NETFS_READ_SINGLE:
203 case NETFS_READ_FOR_WRITE:
204 case NETFS_UNBUFFERED_READ:
205 case NETFS_DIO_READ:
206 return;
207 default:
208 break;
209 }
210
211 switch (subreq->error) {
212 case -EACCES:
213 case -EPERM:
214 case -ENOKEY:
215 case -EKEYEXPIRED:
216 case -EKEYREJECTED:
217 case -EKEYREVOKED:
218 afs_get_writeback_key(wreq);
219 if (!wreq->netfs_priv)
220 stream->failed = true;
221 break;
222 }
223}
224
225/*
226 * write some of the pending data back to the server
227 */
228int afs_writepages(struct address_space *mapping, struct writeback_control *wbc)
229{
230 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
231 int ret;
232
233 /* We have to be careful as we can end up racing with setattr()
234 * truncating the pagecache since the caller doesn't take a lock here
235 * to prevent it.
236 */
237 if (wbc->sync_mode == WB_SYNC_ALL)
238 down_read(&vnode->validate_lock);
239 else if (!down_read_trylock(&vnode->validate_lock))
240 return 0;
241
242 ret = netfs_writepages(mapping, wbc);
243 up_read(&vnode->validate_lock);
244 return ret;
245}
246
247/*
248 * flush any dirty pages for this process, and check for write errors.
249 * - the return status from this call provides a reliable indication of
250 * whether any write errors occurred for this process.
251 */
252int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
253{
254 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
255 struct afs_file *af = file->private_data;
256 int ret;
257
258 _enter("{%llx:%llu},{n=%pD},%d",
259 vnode->fid.vid, vnode->fid.vnode, file,
260 datasync);
261
262 ret = afs_validate(vnode, af->key);
263 if (ret < 0)
264 return ret;
265
266 return file_write_and_wait_range(file, start, end);
267}
268
269/*
270 * notification that a previously read-only page is about to become writable
271 * - if it returns an error, the caller will deliver a bus error signal
272 */
273vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
274{
275 struct file *file = vmf->vma->vm_file;
276
277 if (afs_validate(AFS_FS_I(file_inode(file)), afs_file_key(file)) < 0)
278 return VM_FAULT_SIGBUS;
279 return netfs_page_mkwrite(vmf, NULL);
280}
281
282/*
283 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock.
284 */
285void afs_prune_wb_keys(struct afs_vnode *vnode)
286{
287 LIST_HEAD(graveyard);
288 struct afs_wb_key *wbk, *tmp;
289
290 /* Discard unused keys */
291 spin_lock(&vnode->wb_lock);
292
293 if (!mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
294 !mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_DIRTY)) {
295 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
296 if (refcount_read(&wbk->usage) == 1)
297 list_move(&wbk->vnode_link, &graveyard);
298 }
299 }
300
301 spin_unlock(&vnode->wb_lock);
302
303 while (!list_empty(&graveyard)) {
304 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
305 list_del(&wbk->vnode_link);
306 afs_put_wb_key(wbk);
307 }
308}