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 */
afs_pages_written_back(struct afs_vnode * vnode,loff_t start,unsigned int len)21 static 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 */
afs_get_writeback_key(struct netfs_io_request * wreq)36 static 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(wreq->inode);
40
41 key_put(wreq->netfs_priv);
42 wreq->netfs_priv = NULL;
43 wreq->netfs_priv2 = NULL;
44
45 spin_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(wbk->key) == 0) {
54 refcount_inc(&wbk->usage);
55 wreq->netfs_priv = key_get(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(&vnode->wb_lock);
63
64 afs_put_wb_key(old);
65 }
66
afs_store_data_success(struct afs_operation * op)67 static 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, op->store.pos, op->store.size);
75 afs_stat_v(vnode, n_stores);
76 atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes);
77 }
78 }
79
80 static 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 */
afs_prepare_write(struct netfs_io_subrequest * subreq)90 void 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 */
afs_issue_write_worker(struct work_struct * work)103 static 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(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, false);
124
125 if (!test_bit(NETFS_SREQ_RETRYING, &subreq->flags)) {
126 set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
127 return netfs_write_subrequest_terminated(subreq, -EAGAIN, false);
128 }
129 #endif
130
131 op = afs_alloc_operation(wreq->netfs_priv, vnode->volume);
132 if (IS_ERR(op))
133 return netfs_write_subrequest_terminated(subreq, -EAGAIN, false);
134
135 afs_op_set_vnode(op, 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(&vnode->netfs.inode);
148
149 afs_wait_for_operation(op);
150 ret = afs_put_operation(op);
151 switch (ret) {
152 case -EACCES:
153 case -EPERM:
154 case -ENOKEY:
155 case -EKEYEXPIRED:
156 case -EKEYREJECTED:
157 case -EKEYREVOKED:
158 /* If there are more keys we can try, use the retry algorithm
159 * to rotate the keys.
160 */
161 if (wreq->netfs_priv2)
162 set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
163 break;
164 }
165
166 netfs_write_subrequest_terminated(subreq, ret < 0 ? ret : subreq->len, false);
167 }
168
afs_issue_write(struct netfs_io_subrequest * subreq)169 void afs_issue_write(struct netfs_io_subrequest *subreq)
170 {
171 subreq->work.func = afs_issue_write_worker;
172 if (!queue_work(system_unbound_wq, &subreq->work))
173 WARN_ON_ONCE(1);
174 }
175
176 /*
177 * Writeback calls this when it finds a folio that needs uploading. This isn't
178 * called if writeback only has copy-to-cache to deal with.
179 */
afs_begin_writeback(struct netfs_io_request * wreq)180 void afs_begin_writeback(struct netfs_io_request *wreq)
181 {
182 afs_get_writeback_key(wreq);
183 wreq->io_streams[0].avail = true;
184 }
185
186 /*
187 * Prepare to retry the writes in request. Use this to try rotating the
188 * available writeback keys.
189 */
afs_retry_request(struct netfs_io_request * wreq,struct netfs_io_stream * stream)190 void afs_retry_request(struct netfs_io_request *wreq, struct netfs_io_stream *stream)
191 {
192 struct netfs_io_subrequest *subreq =
193 list_first_entry(&stream->subrequests,
194 struct netfs_io_subrequest, rreq_link);
195
196 switch (subreq->error) {
197 case -EACCES:
198 case -EPERM:
199 case -ENOKEY:
200 case -EKEYEXPIRED:
201 case -EKEYREJECTED:
202 case -EKEYREVOKED:
203 afs_get_writeback_key(wreq);
204 if (!wreq->netfs_priv)
205 stream->failed = true;
206 break;
207 }
208 }
209
210 /*
211 * write some of the pending data back to the server
212 */
afs_writepages(struct address_space * mapping,struct writeback_control * wbc)213 int afs_writepages(struct address_space *mapping, struct writeback_control *wbc)
214 {
215 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
216 int ret;
217
218 /* We have to be careful as we can end up racing with setattr()
219 * truncating the pagecache since the caller doesn't take a lock here
220 * to prevent it.
221 */
222 if (wbc->sync_mode == WB_SYNC_ALL)
223 down_read(&vnode->validate_lock);
224 else if (!down_read_trylock(&vnode->validate_lock))
225 return 0;
226
227 ret = netfs_writepages(mapping, wbc);
228 up_read(&vnode->validate_lock);
229 return ret;
230 }
231
232 /*
233 * flush any dirty pages for this process, and check for write errors.
234 * - the return status from this call provides a reliable indication of
235 * whether any write errors occurred for this process.
236 */
afs_fsync(struct file * file,loff_t start,loff_t end,int datasync)237 int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
238 {
239 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
240 struct afs_file *af = file->private_data;
241 int ret;
242
243 _enter("{%llx:%llu},{n=%pD},%d",
244 vnode->fid.vid, vnode->fid.vnode, file,
245 datasync);
246
247 ret = afs_validate(vnode, af->key);
248 if (ret < 0)
249 return ret;
250
251 return file_write_and_wait_range(file, start, end);
252 }
253
254 /*
255 * notification that a previously read-only page is about to become writable
256 * - if it returns an error, the caller will deliver a bus error signal
257 */
afs_page_mkwrite(struct vm_fault * vmf)258 vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
259 {
260 struct file *file = vmf->vma->vm_file;
261
262 if (afs_validate(AFS_FS_I(file_inode(file)), afs_file_key(file)) < 0)
263 return VM_FAULT_SIGBUS;
264 return netfs_page_mkwrite(vmf, NULL);
265 }
266
267 /*
268 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock.
269 */
afs_prune_wb_keys(struct afs_vnode * vnode)270 void afs_prune_wb_keys(struct afs_vnode *vnode)
271 {
272 LIST_HEAD(graveyard);
273 struct afs_wb_key *wbk, *tmp;
274
275 /* Discard unused keys */
276 spin_lock(&vnode->wb_lock);
277
278 if (!mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
279 !mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_DIRTY)) {
280 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
281 if (refcount_read(&wbk->usage) == 1)
282 list_move(&wbk->vnode_link, &graveyard);
283 }
284 }
285
286 spin_unlock(&vnode->wb_lock);
287
288 while (!list_empty(&graveyard)) {
289 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
290 list_del(&wbk->vnode_link);
291 afs_put_wb_key(wbk);
292 }
293 }
294