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 (dhowells@redhat.com)
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/pagevec.h>
14#include <linux/netfs.h>
15#include <trace/events/netfs.h>
16#include "internal.h"
17
18/*
19 * completion of write to server
20 */
21static void afs_pages_written_back(struct afs_vnode *vnode, loff_t start, unsigned int len)
22{
23 _enter("{%llx:%llu},{%x @%llx}",
24 vnode->fid.vid, vnode->fid.vnode, len, start);
25
26 afs_prune_wb_keys(vnode);
27 _leave("");
28}
29
30/*
31 * Find a key to use for the writeback. We cached the keys used to author the
32 * writes on the vnode. wreq->netfs_priv2 will contain the last writeback key
33 * record used or NULL and we need to start from there if it's set.
34 * wreq->netfs_priv will be set to the key itself or NULL.
35 */
36static void afs_get_writeback_key(struct netfs_io_request *wreq)
37{
38 struct afs_wb_key *wbk, *old = wreq->netfs_priv2;
39 struct afs_vnode *vnode = AFS_FS_I(inode: wreq->inode);
40
41 key_put(key: wreq->netfs_priv);
42 wreq->netfs_priv = NULL;
43 wreq->netfs_priv2 = NULL;
44
45 spin_lock(lock: &vnode->wb_lock);
46 if (old)
47 wbk = list_next_entry(old, vnode_link);
48 else
49 wbk = list_first_entry(&vnode->wb_keys, struct afs_wb_key, vnode_link);
50
51 list_for_each_entry_from(wbk, &vnode->wb_keys, vnode_link) {
52 _debug("wbk %u", key_serial(wbk->key));
53 if (key_validate(key: wbk->key) == 0) {
54 refcount_inc(r: &wbk->usage);
55 wreq->netfs_priv = key_get(key: wbk->key);
56 wreq->netfs_priv2 = wbk;
57 _debug("USE WB KEY %u", key_serial(wbk->key));
58 break;
59 }
60 }
61
62 spin_unlock(lock: &vnode->wb_lock);
63
64 afs_put_wb_key(old);
65}
66
67static void afs_store_data_success(struct afs_operation *op)
68{
69 struct afs_vnode *vnode = op->file[0].vnode;
70
71 op->ctime = op->file[0].scb.status.mtime_client;
72 afs_vnode_commit_status(op, &op->file[0]);
73 if (!afs_op_error(op)) {
74 afs_pages_written_back(vnode, start: op->store.pos, len: op->store.size);
75 afs_stat_v(vnode, n_stores);
76 atomic_long_add(i: op->store.size, v: &afs_v2net(vnode)->n_store_bytes);
77 }
78}
79
80static const struct afs_operation_ops afs_store_data_operation = {
81 .issue_afs_rpc = afs_fs_store_data,
82 .issue_yfs_rpc = yfs_fs_store_data,
83 .success = afs_store_data_success,
84};
85
86/*
87 * Prepare a subrequest to write to the server. This sets the max_len
88 * parameter.
89 */
90void afs_prepare_write(struct netfs_io_subrequest *subreq)
91{
92 struct netfs_io_stream *stream = &subreq->rreq->io_streams[subreq->stream_nr];
93
94 //if (test_bit(NETFS_SREQ_RETRYING, &subreq->flags))
95 // subreq->max_len = 512 * 1024;
96 //else
97 stream->sreq_max_len = 256 * 1024 * 1024;
98}
99
100/*
101 * Issue a subrequest to write to the server.
102 */
103static void afs_issue_write_worker(struct work_struct *work)
104{
105 struct netfs_io_subrequest *subreq = container_of(work, struct netfs_io_subrequest, work);
106 struct netfs_io_request *wreq = subreq->rreq;
107 struct afs_operation *op;
108 struct afs_vnode *vnode = AFS_FS_I(inode: wreq->inode);
109 unsigned long long pos = subreq->start + subreq->transferred;
110 size_t len = subreq->len - subreq->transferred;
111 int ret = -ENOKEY;
112
113 _enter("R=%x[%x],%s{%llx:%llu.%u},%llx,%zx",
114 wreq->debug_id, subreq->debug_index,
115 vnode->volume->name,
116 vnode->fid.vid,
117 vnode->fid.vnode,
118 vnode->fid.unique,
119 pos, len);
120
121#if 0 // Error injection
122 if (subreq->debug_index == 3)
123 return netfs_write_subrequest_terminated(subreq, -ENOANO);
124
125 if (!subreq->retry_count) {
126 set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
127 return netfs_write_subrequest_terminated(subreq, -EAGAIN);
128 }
129#endif
130
131 op = afs_alloc_operation(wreq->netfs_priv, vnode->volume);
132 if (IS_ERR(ptr: op))
133 return netfs_write_subrequest_terminated(op: subreq, transferred_or_error: -EAGAIN);
134
135 afs_op_set_vnode(op, n: 0, vnode);
136 op->file[0].dv_delta = 1;
137 op->file[0].modification = true;
138 op->store.pos = pos;
139 op->store.size = len;
140 op->flags |= AFS_OPERATION_UNINTR;
141 op->ops = &afs_store_data_operation;
142
143 afs_begin_vnode_operation(op);
144
145 op->store.write_iter = &subreq->io_iter;
146 op->store.i_size = umax(pos + len, vnode->netfs.remote_i_size);
147 op->mtime = inode_get_mtime(inode: &vnode->netfs.inode);
148
149 afs_wait_for_operation(op);
150 ret = afs_put_operation(op);
151 switch (ret) {
152 case 0:
153 __set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
154 break;
155 case -EACCES:
156 case -EPERM:
157 case -ENOKEY:
158 case -EKEYEXPIRED:
159 case -EKEYREJECTED:
160 case -EKEYREVOKED:
161 /* If there are more keys we can try, use the retry algorithm
162 * to rotate the keys.
163 */
164 if (wreq->netfs_priv2)
165 set_bit(NETFS_SREQ_NEED_RETRY, addr: &subreq->flags);
166 break;
167 }
168
169 netfs_write_subrequest_terminated(op: subreq, transferred_or_error: ret < 0 ? ret : subreq->len);
170}
171
172void afs_issue_write(struct netfs_io_subrequest *subreq)
173{
174 subreq->work.func = afs_issue_write_worker;
175 if (!queue_work(wq: system_dfl_wq, work: &subreq->work))
176 WARN_ON_ONCE(1);
177}
178
179/*
180 * Writeback calls this when it finds a folio that needs uploading. This isn't
181 * called if writeback only has copy-to-cache to deal with.
182 */
183void afs_begin_writeback(struct netfs_io_request *wreq)
184{
185 if (S_ISREG(wreq->inode->i_mode))
186 afs_get_writeback_key(wreq);
187}
188
189/*
190 * Prepare to retry the writes in request. Use this to try rotating the
191 * available writeback keys.
192 */
193void afs_retry_request(struct netfs_io_request *wreq, struct netfs_io_stream *stream)
194{
195 struct netfs_io_subrequest *subreq =
196 list_first_entry(&stream->subrequests,
197 struct netfs_io_subrequest, rreq_link);
198
199 switch (wreq->origin) {
200 case NETFS_READAHEAD:
201 case NETFS_READPAGE:
202 case NETFS_READ_GAPS:
203 case NETFS_READ_SINGLE:
204 case NETFS_READ_FOR_WRITE:
205 case NETFS_UNBUFFERED_READ:
206 case NETFS_DIO_READ:
207 return;
208 default:
209 break;
210 }
211
212 switch (subreq->error) {
213 case -EACCES:
214 case -EPERM:
215 case -ENOKEY:
216 case -EKEYEXPIRED:
217 case -EKEYREJECTED:
218 case -EKEYREVOKED:
219 afs_get_writeback_key(wreq);
220 if (!wreq->netfs_priv)
221 stream->failed = true;
222 break;
223 }
224}
225
226/*
227 * write some of the pending data back to the server
228 */
229int afs_writepages(struct address_space *mapping, struct writeback_control *wbc)
230{
231 struct afs_vnode *vnode = AFS_FS_I(inode: mapping->host);
232 int ret;
233
234 /* We have to be careful as we can end up racing with setattr()
235 * truncating the pagecache since the caller doesn't take a lock here
236 * to prevent it.
237 */
238 if (wbc->sync_mode == WB_SYNC_ALL)
239 down_read(sem: &vnode->validate_lock);
240 else if (!down_read_trylock(sem: &vnode->validate_lock))
241 return 0;
242
243 ret = netfs_writepages(mapping, wbc);
244 up_read(sem: &vnode->validate_lock);
245 return ret;
246}
247
248/*
249 * flush any dirty pages for this process, and check for write errors.
250 * - the return status from this call provides a reliable indication of
251 * whether any write errors occurred for this process.
252 */
253int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
254{
255 struct afs_vnode *vnode = AFS_FS_I(inode: file_inode(f: file));
256 struct afs_file *af = file->private_data;
257 int ret;
258
259 _enter("{%llx:%llu},{n=%pD},%d",
260 vnode->fid.vid, vnode->fid.vnode, file,
261 datasync);
262
263 ret = afs_validate(vnode, key: af->key);
264 if (ret < 0)
265 return ret;
266
267 return file_write_and_wait_range(file, start, end);
268}
269
270/*
271 * notification that a previously read-only page is about to become writable
272 * - if it returns an error, the caller will deliver a bus error signal
273 */
274vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
275{
276 struct file *file = vmf->vma->vm_file;
277
278 if (afs_validate(vnode: AFS_FS_I(inode: file_inode(f: file)), key: afs_file_key(file)) < 0)
279 return VM_FAULT_SIGBUS;
280 return netfs_page_mkwrite(vmf, NULL);
281}
282
283/*
284 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock.
285 */
286void afs_prune_wb_keys(struct afs_vnode *vnode)
287{
288 LIST_HEAD(graveyard);
289 struct afs_wb_key *wbk, *tmp;
290
291 /* Discard unused keys */
292 spin_lock(lock: &vnode->wb_lock);
293
294 if (!mapping_tagged(mapping: &vnode->netfs.inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
295 !mapping_tagged(mapping: &vnode->netfs.inode.i_data, PAGECACHE_TAG_DIRTY)) {
296 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
297 if (refcount_read(r: &wbk->usage) == 1)
298 list_move(list: &wbk->vnode_link, head: &graveyard);
299 }
300 }
301
302 spin_unlock(lock: &vnode->wb_lock);
303
304 while (!list_empty(head: &graveyard)) {
305 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
306 list_del(entry: &wbk->vnode_link);
307 afs_put_wb_key(wbk);
308 }
309}
310

source code of linux/fs/afs/write.c