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. *_wbk will contain the last writeback key used or NULL
33 * and we need to start from there if it's set.
34 */
35static int afs_get_writeback_key(struct afs_vnode *vnode,
36 struct afs_wb_key **_wbk)
37{
38 struct afs_wb_key *wbk = NULL;
39 struct list_head *p;
40 int ret = -ENOKEY, ret2;
41
42 spin_lock(lock: &vnode->wb_lock);
43 if (*_wbk)
44 p = (*_wbk)->vnode_link.next;
45 else
46 p = vnode->wb_keys.next;
47
48 while (p != &vnode->wb_keys) {
49 wbk = list_entry(p, struct afs_wb_key, vnode_link);
50 _debug("wbk %u", key_serial(wbk->key));
51 ret2 = key_validate(key: wbk->key);
52 if (ret2 == 0) {
53 refcount_inc(r: &wbk->usage);
54 _debug("USE WB KEY %u", key_serial(wbk->key));
55 break;
56 }
57
58 wbk = NULL;
59 if (ret == -ENOKEY)
60 ret = ret2;
61 p = p->next;
62 }
63
64 spin_unlock(lock: &vnode->wb_lock);
65 if (*_wbk)
66 afs_put_wb_key(*_wbk);
67 *_wbk = wbk;
68 return 0;
69}
70
71static void afs_store_data_success(struct afs_operation *op)
72{
73 struct afs_vnode *vnode = op->file[0].vnode;
74
75 op->ctime = op->file[0].scb.status.mtime_client;
76 afs_vnode_commit_status(op, &op->file[0]);
77 if (!afs_op_error(op)) {
78 if (!op->store.laundering)
79 afs_pages_written_back(vnode, start: op->store.pos, len: op->store.size);
80 afs_stat_v(vnode, n_stores);
81 atomic_long_add(i: op->store.size, v: &afs_v2net(vnode)->n_store_bytes);
82 }
83}
84
85static const struct afs_operation_ops afs_store_data_operation = {
86 .issue_afs_rpc = afs_fs_store_data,
87 .issue_yfs_rpc = yfs_fs_store_data,
88 .success = afs_store_data_success,
89};
90
91/*
92 * write to a file
93 */
94static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t pos,
95 bool laundering)
96{
97 struct afs_operation *op;
98 struct afs_wb_key *wbk = NULL;
99 loff_t size = iov_iter_count(i: iter);
100 int ret = -ENOKEY;
101
102 _enter("%s{%llx:%llu.%u},%llx,%llx",
103 vnode->volume->name,
104 vnode->fid.vid,
105 vnode->fid.vnode,
106 vnode->fid.unique,
107 size, pos);
108
109 ret = afs_get_writeback_key(vnode, wbk: &wbk);
110 if (ret) {
111 _leave(" = %d [no keys]", ret);
112 return ret;
113 }
114
115 op = afs_alloc_operation(wbk->key, vnode->volume);
116 if (IS_ERR(ptr: op)) {
117 afs_put_wb_key(wbk);
118 return -ENOMEM;
119 }
120
121 afs_op_set_vnode(op, n: 0, vnode);
122 op->file[0].dv_delta = 1;
123 op->file[0].modification = true;
124 op->store.pos = pos;
125 op->store.size = size;
126 op->store.laundering = laundering;
127 op->flags |= AFS_OPERATION_UNINTR;
128 op->ops = &afs_store_data_operation;
129
130try_next_key:
131 afs_begin_vnode_operation(op);
132
133 op->store.write_iter = iter;
134 op->store.i_size = max(pos + size, vnode->netfs.remote_i_size);
135 op->mtime = inode_get_mtime(inode: &vnode->netfs.inode);
136
137 afs_wait_for_operation(op);
138
139 switch (afs_op_error(op)) {
140 case -EACCES:
141 case -EPERM:
142 case -ENOKEY:
143 case -EKEYEXPIRED:
144 case -EKEYREJECTED:
145 case -EKEYREVOKED:
146 _debug("next");
147
148 ret = afs_get_writeback_key(vnode, wbk: &wbk);
149 if (ret == 0) {
150 key_put(key: op->key);
151 op->key = key_get(key: wbk->key);
152 goto try_next_key;
153 }
154 break;
155 }
156
157 afs_put_wb_key(wbk);
158 _leave(" = %d", afs_op_error(op));
159 return afs_put_operation(op);
160}
161
162static void afs_upload_to_server(struct netfs_io_subrequest *subreq)
163{
164 struct afs_vnode *vnode = AFS_FS_I(inode: subreq->rreq->inode);
165 ssize_t ret;
166
167 _enter("%x[%x],%zx",
168 subreq->rreq->debug_id, subreq->debug_index, subreq->io_iter.count);
169
170 trace_netfs_sreq(sreq: subreq, what: netfs_sreq_trace_submit);
171 ret = afs_store_data(vnode, iter: &subreq->io_iter, pos: subreq->start,
172 laundering: subreq->rreq->origin == NETFS_LAUNDER_WRITE);
173 netfs_write_subrequest_terminated(op: subreq, transferred_or_error: ret < 0 ? ret : subreq->len,
174 was_async: false);
175}
176
177static void afs_upload_to_server_worker(struct work_struct *work)
178{
179 struct netfs_io_subrequest *subreq =
180 container_of(work, struct netfs_io_subrequest, work);
181
182 afs_upload_to_server(subreq);
183}
184
185/*
186 * Set up write requests for a writeback slice. We need to add a write request
187 * for each write we want to make.
188 */
189void afs_create_write_requests(struct netfs_io_request *wreq, loff_t start, size_t len)
190{
191 struct netfs_io_subrequest *subreq;
192
193 _enter("%x,%llx-%llx", wreq->debug_id, start, start + len);
194
195 subreq = netfs_create_write_request(wreq, dest: NETFS_UPLOAD_TO_SERVER,
196 start, len, worker: afs_upload_to_server_worker);
197 if (subreq)
198 netfs_queue_write_request(subreq);
199}
200
201/*
202 * write some of the pending data back to the server
203 */
204int afs_writepages(struct address_space *mapping, struct writeback_control *wbc)
205{
206 struct afs_vnode *vnode = AFS_FS_I(inode: mapping->host);
207 int ret;
208
209 /* We have to be careful as we can end up racing with setattr()
210 * truncating the pagecache since the caller doesn't take a lock here
211 * to prevent it.
212 */
213 if (wbc->sync_mode == WB_SYNC_ALL)
214 down_read(sem: &vnode->validate_lock);
215 else if (!down_read_trylock(sem: &vnode->validate_lock))
216 return 0;
217
218 ret = netfs_writepages(mapping, wbc);
219 up_read(sem: &vnode->validate_lock);
220 return ret;
221}
222
223/*
224 * flush any dirty pages for this process, and check for write errors.
225 * - the return status from this call provides a reliable indication of
226 * whether any write errors occurred for this process.
227 */
228int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
229{
230 struct afs_vnode *vnode = AFS_FS_I(inode: file_inode(f: file));
231 struct afs_file *af = file->private_data;
232 int ret;
233
234 _enter("{%llx:%llu},{n=%pD},%d",
235 vnode->fid.vid, vnode->fid.vnode, file,
236 datasync);
237
238 ret = afs_validate(vnode, key: af->key);
239 if (ret < 0)
240 return ret;
241
242 return file_write_and_wait_range(file, start, end);
243}
244
245/*
246 * notification that a previously read-only page is about to become writable
247 * - if it returns an error, the caller will deliver a bus error signal
248 */
249vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
250{
251 struct file *file = vmf->vma->vm_file;
252
253 if (afs_validate(vnode: AFS_FS_I(inode: file_inode(f: file)), key: afs_file_key(file)) < 0)
254 return VM_FAULT_SIGBUS;
255 return netfs_page_mkwrite(vmf, NULL);
256}
257
258/*
259 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock.
260 */
261void afs_prune_wb_keys(struct afs_vnode *vnode)
262{
263 LIST_HEAD(graveyard);
264 struct afs_wb_key *wbk, *tmp;
265
266 /* Discard unused keys */
267 spin_lock(lock: &vnode->wb_lock);
268
269 if (!mapping_tagged(mapping: &vnode->netfs.inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
270 !mapping_tagged(mapping: &vnode->netfs.inode.i_data, PAGECACHE_TAG_DIRTY)) {
271 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
272 if (refcount_read(r: &wbk->usage) == 1)
273 list_move(list: &wbk->vnode_link, head: &graveyard);
274 }
275 }
276
277 spin_unlock(lock: &vnode->wb_lock);
278
279 while (!list_empty(head: &graveyard)) {
280 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
281 list_del(entry: &wbk->vnode_link);
282 afs_put_wb_key(wbk);
283 }
284}
285

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