Linux kernel mirror (for testing)
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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * V9FS cache definitions.
4 *
5 * Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
6 */
7
8#include <linux/jiffies.h>
9#include <linux/file.h>
10#include <linux/slab.h>
11#include <linux/stat.h>
12#include <linux/sched.h>
13#include <linux/fs.h>
14#include <net/9p/9p.h>
15
16#include "v9fs.h"
17#include "cache.h"
18
19#define CACHETAG_LEN 11
20
21struct fscache_netfs v9fs_cache_netfs = {
22 .name = "9p",
23 .version = 0,
24};
25
26/**
27 * v9fs_random_cachetag - Generate a random tag to be associated
28 * with a new cache session.
29 *
30 * The value of jiffies is used for a fairly randomly cache tag.
31 */
32
33static
34int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
35{
36 v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);
37 if (!v9ses->cachetag)
38 return -ENOMEM;
39
40 return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
41}
42
43const struct fscache_cookie_def v9fs_cache_session_index_def = {
44 .name = "9P.session",
45 .type = FSCACHE_COOKIE_TYPE_INDEX,
46};
47
48void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
49{
50 /* If no cache session tag was specified, we generate a random one. */
51 if (!v9ses->cachetag) {
52 if (v9fs_random_cachetag(v9ses) < 0) {
53 v9ses->fscache = NULL;
54 return;
55 }
56 }
57
58 v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
59 &v9fs_cache_session_index_def,
60 v9ses->cachetag,
61 strlen(v9ses->cachetag),
62 NULL, 0,
63 v9ses, 0, true);
64 p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
65 v9ses, v9ses->fscache);
66}
67
68void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
69{
70 p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",
71 v9ses, v9ses->fscache);
72 fscache_relinquish_cookie(v9ses->fscache, NULL, false);
73 v9ses->fscache = NULL;
74}
75
76static enum
77fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
78 const void *buffer,
79 uint16_t buflen,
80 loff_t object_size)
81{
82 const struct v9fs_inode *v9inode = cookie_netfs_data;
83
84 if (buflen != sizeof(v9inode->qid.version))
85 return FSCACHE_CHECKAUX_OBSOLETE;
86
87 if (memcmp(buffer, &v9inode->qid.version,
88 sizeof(v9inode->qid.version)))
89 return FSCACHE_CHECKAUX_OBSOLETE;
90
91 return FSCACHE_CHECKAUX_OKAY;
92}
93
94const struct fscache_cookie_def v9fs_cache_inode_index_def = {
95 .name = "9p.inode",
96 .type = FSCACHE_COOKIE_TYPE_DATAFILE,
97 .check_aux = v9fs_cache_inode_check_aux,
98};
99
100void v9fs_cache_inode_get_cookie(struct inode *inode)
101{
102 struct v9fs_inode *v9inode;
103 struct v9fs_session_info *v9ses;
104
105 if (!S_ISREG(inode->i_mode))
106 return;
107
108 v9inode = V9FS_I(inode);
109 if (v9inode->fscache)
110 return;
111
112 v9ses = v9fs_inode2v9ses(inode);
113 v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
114 &v9fs_cache_inode_index_def,
115 &v9inode->qid.path,
116 sizeof(v9inode->qid.path),
117 &v9inode->qid.version,
118 sizeof(v9inode->qid.version),
119 v9inode,
120 i_size_read(&v9inode->vfs_inode),
121 true);
122
123 p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
124 inode, v9inode->fscache);
125}
126
127void v9fs_cache_inode_put_cookie(struct inode *inode)
128{
129 struct v9fs_inode *v9inode = V9FS_I(inode);
130
131 if (!v9inode->fscache)
132 return;
133 p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
134 inode, v9inode->fscache);
135
136 fscache_relinquish_cookie(v9inode->fscache, &v9inode->qid.version,
137 false);
138 v9inode->fscache = NULL;
139}
140
141void v9fs_cache_inode_flush_cookie(struct inode *inode)
142{
143 struct v9fs_inode *v9inode = V9FS_I(inode);
144
145 if (!v9inode->fscache)
146 return;
147 p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
148 inode, v9inode->fscache);
149
150 fscache_relinquish_cookie(v9inode->fscache, NULL, true);
151 v9inode->fscache = NULL;
152}
153
154void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
155{
156 struct v9fs_inode *v9inode = V9FS_I(inode);
157
158 if (!v9inode->fscache)
159 return;
160
161 mutex_lock(&v9inode->fscache_lock);
162
163 if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
164 v9fs_cache_inode_flush_cookie(inode);
165 else
166 v9fs_cache_inode_get_cookie(inode);
167
168 mutex_unlock(&v9inode->fscache_lock);
169}
170
171void v9fs_cache_inode_reset_cookie(struct inode *inode)
172{
173 struct v9fs_inode *v9inode = V9FS_I(inode);
174 struct v9fs_session_info *v9ses;
175 struct fscache_cookie *old;
176
177 if (!v9inode->fscache)
178 return;
179
180 old = v9inode->fscache;
181
182 mutex_lock(&v9inode->fscache_lock);
183 fscache_relinquish_cookie(v9inode->fscache, NULL, true);
184
185 v9ses = v9fs_inode2v9ses(inode);
186 v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
187 &v9fs_cache_inode_index_def,
188 &v9inode->qid.path,
189 sizeof(v9inode->qid.path),
190 &v9inode->qid.version,
191 sizeof(v9inode->qid.version),
192 v9inode,
193 i_size_read(&v9inode->vfs_inode),
194 true);
195 p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
196 inode, old, v9inode->fscache);
197
198 mutex_unlock(&v9inode->fscache_lock);
199}
200
201int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
202{
203 struct inode *inode = page->mapping->host;
204 struct v9fs_inode *v9inode = V9FS_I(inode);
205
206 BUG_ON(!v9inode->fscache);
207
208 return fscache_maybe_release_page(v9inode->fscache, page, gfp);
209}
210
211void __v9fs_fscache_invalidate_page(struct page *page)
212{
213 struct inode *inode = page->mapping->host;
214 struct v9fs_inode *v9inode = V9FS_I(inode);
215
216 BUG_ON(!v9inode->fscache);
217
218 if (PageFsCache(page)) {
219 fscache_wait_on_page_write(v9inode->fscache, page);
220 BUG_ON(!PageLocked(page));
221 fscache_uncache_page(v9inode->fscache, page);
222 }
223}
224
225static void v9fs_vfs_readpage_complete(struct page *page, void *data,
226 int error)
227{
228 if (!error)
229 SetPageUptodate(page);
230
231 unlock_page(page);
232}
233
234/**
235 * __v9fs_readpage_from_fscache - read a page from cache
236 *
237 * Returns 0 if the pages are in cache and a BIO is submitted,
238 * 1 if the pages are not in cache and -error otherwise.
239 */
240
241int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
242{
243 int ret;
244 const struct v9fs_inode *v9inode = V9FS_I(inode);
245
246 p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
247 if (!v9inode->fscache)
248 return -ENOBUFS;
249
250 ret = fscache_read_or_alloc_page(v9inode->fscache,
251 page,
252 v9fs_vfs_readpage_complete,
253 NULL,
254 GFP_KERNEL);
255 switch (ret) {
256 case -ENOBUFS:
257 case -ENODATA:
258 p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret);
259 return 1;
260 case 0:
261 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
262 return ret;
263 default:
264 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
265 return ret;
266 }
267}
268
269/**
270 * __v9fs_readpages_from_fscache - read multiple pages from cache
271 *
272 * Returns 0 if the pages are in cache and a BIO is submitted,
273 * 1 if the pages are not in cache and -error otherwise.
274 */
275
276int __v9fs_readpages_from_fscache(struct inode *inode,
277 struct address_space *mapping,
278 struct list_head *pages,
279 unsigned *nr_pages)
280{
281 int ret;
282 const struct v9fs_inode *v9inode = V9FS_I(inode);
283
284 p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages);
285 if (!v9inode->fscache)
286 return -ENOBUFS;
287
288 ret = fscache_read_or_alloc_pages(v9inode->fscache,
289 mapping, pages, nr_pages,
290 v9fs_vfs_readpage_complete,
291 NULL,
292 mapping_gfp_mask(mapping));
293 switch (ret) {
294 case -ENOBUFS:
295 case -ENODATA:
296 p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret);
297 return 1;
298 case 0:
299 BUG_ON(!list_empty(pages));
300 BUG_ON(*nr_pages != 0);
301 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
302 return ret;
303 default:
304 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
305 return ret;
306 }
307}
308
309/**
310 * __v9fs_readpage_to_fscache - write a page to the cache
311 *
312 */
313
314void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
315{
316 int ret;
317 const struct v9fs_inode *v9inode = V9FS_I(inode);
318
319 p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
320 ret = fscache_write_page(v9inode->fscache, page,
321 i_size_read(&v9inode->vfs_inode), GFP_KERNEL);
322 p9_debug(P9_DEBUG_FSC, "ret = %d\n", ret);
323 if (ret != 0)
324 v9fs_uncache_page(inode, page);
325}
326
327/*
328 * wait for a page to complete writing to the cache
329 */
330void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
331{
332 const struct v9fs_inode *v9inode = V9FS_I(inode);
333 p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
334 if (PageFsCache(page))
335 fscache_wait_on_page_write(v9inode->fscache, page);
336}