1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Cache data I/O routines
3 *
4 * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7 #define FSCACHE_DEBUG_LEVEL OPERATION
8 #include <linux/fscache-cache.h>
9 #include <linux/uio.h>
10 #include <linux/bvec.h>
11 #include <linux/slab.h>
12 #include <linux/uio.h>
13 #include "internal.h"
14
15 /**
16 * fscache_wait_for_operation - Wait for an object become accessible
17 * @cres: The cache resources for the operation being performed
18 * @want_state: The minimum state the object must be at
19 *
20 * See if the target cache object is at the specified minimum state of
21 * accessibility yet, and if not, wait for it.
22 */
23 bool fscache_wait_for_operation(struct netfs_cache_resources *cres,
24 enum fscache_want_state want_state)
25 {
26 struct fscache_cookie *cookie = fscache_cres_cookie(cres);
27 enum fscache_cookie_state state;
28
29 again:
30 if (!fscache_cache_is_live(cookie->volume->cache)) {
31 _leave(" [broken]");
32 return false;
33 }
34
35 state = fscache_cookie_state(cookie);
36 _enter("c=%08x{%u},%x", cookie->debug_id, state, want_state);
37
38 switch (state) {
39 case FSCACHE_COOKIE_STATE_CREATING:
40 case FSCACHE_COOKIE_STATE_INVALIDATING:
41 if (want_state == FSCACHE_WANT_PARAMS)
42 goto ready; /* There can be no content */
43 fallthrough;
44 case FSCACHE_COOKIE_STATE_LOOKING_UP:
45 case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
46 wait_var_event(&cookie->state,
47 fscache_cookie_state(cookie) != state);
48 goto again;
49
50 case FSCACHE_COOKIE_STATE_ACTIVE:
51 goto ready;
52 case FSCACHE_COOKIE_STATE_DROPPED:
53 case FSCACHE_COOKIE_STATE_RELINQUISHING:
54 default:
55 _leave(" [not live]");
56 return false;
57 }
58
59 ready:
60 if (!cres->cache_priv2)
61 return cookie->volume->cache->ops->begin_operation(cres, want_state);
62 return true;
63 }
64 EXPORT_SYMBOL(fscache_wait_for_operation);
65
66 /*
67 * Begin an I/O operation on the cache, waiting till we reach the right state.
68 *
69 * Attaches the resources required to the operation resources record.
70 */
71 static int fscache_begin_operation(struct netfs_cache_resources *cres,
72 struct fscache_cookie *cookie,
73 enum fscache_want_state want_state,
74 enum fscache_access_trace why)
75 {
76 enum fscache_cookie_state state;
77 long timeo;
78 bool once_only = false;
79
80 cres->ops = NULL;
81 cres->cache_priv = cookie;
82 cres->cache_priv2 = NULL;
83 cres->debug_id = cookie->debug_id;
84 cres->inval_counter = cookie->inval_counter;
85
86 if (!fscache_begin_cookie_access(cookie, why)) {
87 cres->cache_priv = NULL;
88 return -ENOBUFS;
89 }
90
91 again:
92 spin_lock(&cookie->lock);
93
94 state = fscache_cookie_state(cookie);
95 _enter("c=%08x{%u},%x", cookie->debug_id, state, want_state);
96
97 switch (state) {
98 case FSCACHE_COOKIE_STATE_LOOKING_UP:
99 case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
100 case FSCACHE_COOKIE_STATE_INVALIDATING:
101 goto wait_for_file_wrangling;
102 case FSCACHE_COOKIE_STATE_CREATING:
103 if (want_state == FSCACHE_WANT_PARAMS)
104 goto ready; /* There can be no content */
105 goto wait_for_file_wrangling;
106 case FSCACHE_COOKIE_STATE_ACTIVE:
107 goto ready;
108 case FSCACHE_COOKIE_STATE_DROPPED:
109 case FSCACHE_COOKIE_STATE_RELINQUISHING:
110 WARN(1, "Can't use cookie in state %u\n", cookie->state);
111 goto not_live;
112 default:
113 goto not_live;
114 }
115
116 ready:
117 spin_unlock(&cookie->lock);
118 if (!cookie->volume->cache->ops->begin_operation(cres, want_state))
119 goto failed;
120 return 0;
121
122 wait_for_file_wrangling:
123 spin_unlock(&cookie->lock);
124 trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref),
125 atomic_read(&cookie->n_accesses),
126 fscache_access_io_wait);
127 timeo = wait_var_event_timeout(&cookie->state,
128 fscache_cookie_state(cookie) != state, 20 * HZ);
129 if (timeo <= 1 && !once_only) {
130 pr_warn("%s: cookie state change wait timed out: cookie->state=%u state=%u",
131 __func__, fscache_cookie_state(cookie), state);
132 fscache_print_cookie(cookie, 'O');
133 once_only = true;
134 }
135 goto again;
136
137 not_live:
138 spin_unlock(&cookie->lock);
139 failed:
140 cres->cache_priv = NULL;
141 cres->ops = NULL;
142 fscache_end_cookie_access(cookie, fscache_access_io_not_live);
143 _leave(" = -ENOBUFS");
144 return -ENOBUFS;
145 }
146
147 int __fscache_begin_read_operation(struct netfs_cache_resources *cres,
148 struct fscache_cookie *cookie)
149 {
150 return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS,
151 fscache_access_io_read);
152 }
153 EXPORT_SYMBOL(__fscache_begin_read_operation);
154
155 int __fscache_begin_write_operation(struct netfs_cache_resources *cres,
156 struct fscache_cookie *cookie)
157 {
158 return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS,
159 fscache_access_io_write);
160 }
161 EXPORT_SYMBOL(__fscache_begin_write_operation);
162
163 struct fscache_write_request {
164 struct netfs_cache_resources cache_resources;
165 struct address_space *mapping;
166 loff_t start;
167 size_t len;
168 bool set_bits;
169 bool using_pgpriv2;
170 netfs_io_terminated_t term_func;
171 void *term_func_priv;
172 };
173
174 void __fscache_clear_page_bits(struct address_space *mapping,
175 loff_t start, size_t len)
176 {
177 pgoff_t first = start / PAGE_SIZE;
178 pgoff_t last = (start + len - 1) / PAGE_SIZE;
179 struct page *page;
180
181 if (len) {
182 XA_STATE(xas, &mapping->i_pages, first);
183
184 rcu_read_lock();
185 xas_for_each(&xas, page, last) {
186 folio_end_private_2(page_folio(page));
187 }
188 rcu_read_unlock();
189 }
190 }
191 EXPORT_SYMBOL(__fscache_clear_page_bits);
192
193 /*
194 * Deal with the completion of writing the data to the cache.
195 */
196 static void fscache_wreq_done(void *priv, ssize_t transferred_or_error,
197 bool was_async)
198 {
199 struct fscache_write_request *wreq = priv;
200
201 if (wreq->using_pgpriv2)
202 fscache_clear_page_bits(wreq->mapping, wreq->start, wreq->len,
203 wreq->set_bits);
204
205 if (wreq->term_func)
206 wreq->term_func(wreq->term_func_priv, transferred_or_error,
207 was_async);
208 fscache_end_operation(&wreq->cache_resources);
209 kfree(wreq);
210 }
211
212 void __fscache_write_to_cache(struct fscache_cookie *cookie,
213 struct address_space *mapping,
214 loff_t start, size_t len, loff_t i_size,
215 netfs_io_terminated_t term_func,
216 void *term_func_priv,
217 bool using_pgpriv2, bool cond)
218 {
219 struct fscache_write_request *wreq;
220 struct netfs_cache_resources *cres;
221 struct iov_iter iter;
222 int ret = -ENOBUFS;
223
224 if (len == 0)
225 goto abandon;
226
227 _enter("%llx,%zx", start, len);
228
229 wreq = kzalloc(sizeof(struct fscache_write_request), GFP_NOFS);
230 if (!wreq)
231 goto abandon;
232 wreq->mapping = mapping;
233 wreq->start = start;
234 wreq->len = len;
235 wreq->using_pgpriv2 = using_pgpriv2;
236 wreq->set_bits = cond;
237 wreq->term_func = term_func;
238 wreq->term_func_priv = term_func_priv;
239
240 cres = &wreq->cache_resources;
241 if (fscache_begin_operation(cres, cookie, FSCACHE_WANT_WRITE,
242 fscache_access_io_write) < 0)
243 goto abandon_free;
244
245 ret = cres->ops->prepare_write(cres, &start, &len, len, i_size, false);
246 if (ret < 0)
247 goto abandon_end;
248
249 /* TODO: Consider clearing page bits now for space the write isn't
250 * covering. This is more complicated than it appears when THPs are
251 * taken into account.
252 */
253
254 iov_iter_xarray(&iter, ITER_SOURCE, &mapping->i_pages, start, len);
255 fscache_write(cres, start, &iter, fscache_wreq_done, wreq);
256 return;
257
258 abandon_end:
259 return fscache_wreq_done(wreq, ret, false);
260 abandon_free:
261 kfree(wreq);
262 abandon:
263 if (using_pgpriv2)
264 fscache_clear_page_bits(mapping, start, len, cond);
265 if (term_func)
266 term_func(term_func_priv, ret, false);
267 }
268 EXPORT_SYMBOL(__fscache_write_to_cache);
269
270 /*
271 * Change the size of a backing object.
272 */
273 void __fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size)
274 {
275 struct netfs_cache_resources cres;
276
277 trace_fscache_resize(cookie, new_size);
278 if (fscache_begin_operation(&cres, cookie, FSCACHE_WANT_WRITE,
279 fscache_access_io_resize) == 0) {
280 fscache_stat(&fscache_n_resizes);
281 set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &cookie->flags);
282
283 /* We cannot defer a resize as we need to do it inside the
284 * netfs's inode lock so that we're serialised with respect to
285 * writes.
286 */
287 cookie->volume->cache->ops->resize_cookie(&cres, new_size);
288 fscache_end_operation(&cres);
289 } else {
290 fscache_stat(&fscache_n_resizes_null);
291 }
292 }
293 EXPORT_SYMBOL(__fscache_resize_cookie);
294
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