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
21 struct 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
33 static
v9fs_random_cachetag(struct v9fs_session_info * v9ses)34 int 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
43 const struct fscache_cookie_def v9fs_cache_session_index_def = {
44 .name = "9P.session",
45 .type = FSCACHE_COOKIE_TYPE_INDEX,
46 };
47
v9fs_cache_session_get_cookie(struct v9fs_session_info * v9ses)48 void 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 kfree(v9ses->cachetag);
55 v9ses->cachetag = NULL;
56 return;
57 }
58 }
59
60 v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
61 &v9fs_cache_session_index_def,
62 v9ses->cachetag,
63 strlen(v9ses->cachetag),
64 NULL, 0,
65 v9ses, 0, true);
66 p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
67 v9ses, v9ses->fscache);
68 }
69
v9fs_cache_session_put_cookie(struct v9fs_session_info * v9ses)70 void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
71 {
72 p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",
73 v9ses, v9ses->fscache);
74 fscache_relinquish_cookie(v9ses->fscache, NULL, false);
75 v9ses->fscache = NULL;
76 }
77
78 static enum
v9fs_cache_inode_check_aux(void * cookie_netfs_data,const void * buffer,uint16_t buflen,loff_t object_size)79 fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
80 const void *buffer,
81 uint16_t buflen,
82 loff_t object_size)
83 {
84 const struct v9fs_inode *v9inode = cookie_netfs_data;
85
86 if (buflen != sizeof(v9inode->qid.version))
87 return FSCACHE_CHECKAUX_OBSOLETE;
88
89 if (memcmp(buffer, &v9inode->qid.version,
90 sizeof(v9inode->qid.version)))
91 return FSCACHE_CHECKAUX_OBSOLETE;
92
93 return FSCACHE_CHECKAUX_OKAY;
94 }
95
96 const struct fscache_cookie_def v9fs_cache_inode_index_def = {
97 .name = "9p.inode",
98 .type = FSCACHE_COOKIE_TYPE_DATAFILE,
99 .check_aux = v9fs_cache_inode_check_aux,
100 };
101
v9fs_cache_inode_get_cookie(struct inode * inode)102 void v9fs_cache_inode_get_cookie(struct inode *inode)
103 {
104 struct v9fs_inode *v9inode;
105 struct v9fs_session_info *v9ses;
106
107 if (!S_ISREG(inode->i_mode))
108 return;
109
110 v9inode = V9FS_I(inode);
111 if (v9inode->fscache)
112 return;
113
114 v9ses = v9fs_inode2v9ses(inode);
115 v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
116 &v9fs_cache_inode_index_def,
117 &v9inode->qid.path,
118 sizeof(v9inode->qid.path),
119 &v9inode->qid.version,
120 sizeof(v9inode->qid.version),
121 v9inode,
122 i_size_read(&v9inode->vfs_inode),
123 true);
124
125 p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
126 inode, v9inode->fscache);
127 }
128
v9fs_cache_inode_put_cookie(struct inode * inode)129 void v9fs_cache_inode_put_cookie(struct inode *inode)
130 {
131 struct v9fs_inode *v9inode = V9FS_I(inode);
132
133 if (!v9inode->fscache)
134 return;
135 p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
136 inode, v9inode->fscache);
137
138 fscache_relinquish_cookie(v9inode->fscache, &v9inode->qid.version,
139 false);
140 v9inode->fscache = NULL;
141 }
142
v9fs_cache_inode_flush_cookie(struct inode * inode)143 void v9fs_cache_inode_flush_cookie(struct inode *inode)
144 {
145 struct v9fs_inode *v9inode = V9FS_I(inode);
146
147 if (!v9inode->fscache)
148 return;
149 p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
150 inode, v9inode->fscache);
151
152 fscache_relinquish_cookie(v9inode->fscache, NULL, true);
153 v9inode->fscache = NULL;
154 }
155
v9fs_cache_inode_set_cookie(struct inode * inode,struct file * filp)156 void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
157 {
158 struct v9fs_inode *v9inode = V9FS_I(inode);
159
160 if (!v9inode->fscache)
161 return;
162
163 mutex_lock(&v9inode->fscache_lock);
164
165 if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
166 v9fs_cache_inode_flush_cookie(inode);
167 else
168 v9fs_cache_inode_get_cookie(inode);
169
170 mutex_unlock(&v9inode->fscache_lock);
171 }
172
v9fs_cache_inode_reset_cookie(struct inode * inode)173 void v9fs_cache_inode_reset_cookie(struct inode *inode)
174 {
175 struct v9fs_inode *v9inode = V9FS_I(inode);
176 struct v9fs_session_info *v9ses;
177 struct fscache_cookie *old;
178
179 if (!v9inode->fscache)
180 return;
181
182 old = v9inode->fscache;
183
184 mutex_lock(&v9inode->fscache_lock);
185 fscache_relinquish_cookie(v9inode->fscache, NULL, true);
186
187 v9ses = v9fs_inode2v9ses(inode);
188 v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
189 &v9fs_cache_inode_index_def,
190 &v9inode->qid.path,
191 sizeof(v9inode->qid.path),
192 &v9inode->qid.version,
193 sizeof(v9inode->qid.version),
194 v9inode,
195 i_size_read(&v9inode->vfs_inode),
196 true);
197 p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
198 inode, old, v9inode->fscache);
199
200 mutex_unlock(&v9inode->fscache_lock);
201 }
202
__v9fs_fscache_release_page(struct page * page,gfp_t gfp)203 int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
204 {
205 struct inode *inode = page->mapping->host;
206 struct v9fs_inode *v9inode = V9FS_I(inode);
207
208 BUG_ON(!v9inode->fscache);
209
210 return fscache_maybe_release_page(v9inode->fscache, page, gfp);
211 }
212
__v9fs_fscache_invalidate_page(struct page * page)213 void __v9fs_fscache_invalidate_page(struct page *page)
214 {
215 struct inode *inode = page->mapping->host;
216 struct v9fs_inode *v9inode = V9FS_I(inode);
217
218 BUG_ON(!v9inode->fscache);
219
220 if (PageFsCache(page)) {
221 fscache_wait_on_page_write(v9inode->fscache, page);
222 BUG_ON(!PageLocked(page));
223 fscache_uncache_page(v9inode->fscache, page);
224 }
225 }
226
v9fs_vfs_readpage_complete(struct page * page,void * data,int error)227 static void v9fs_vfs_readpage_complete(struct page *page, void *data,
228 int error)
229 {
230 if (!error)
231 SetPageUptodate(page);
232
233 unlock_page(page);
234 }
235
236 /**
237 * __v9fs_readpage_from_fscache - read a page from cache
238 *
239 * Returns 0 if the pages are in cache and a BIO is submitted,
240 * 1 if the pages are not in cache and -error otherwise.
241 */
242
__v9fs_readpage_from_fscache(struct inode * inode,struct page * page)243 int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
244 {
245 int ret;
246 const struct v9fs_inode *v9inode = V9FS_I(inode);
247
248 p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
249 if (!v9inode->fscache)
250 return -ENOBUFS;
251
252 ret = fscache_read_or_alloc_page(v9inode->fscache,
253 page,
254 v9fs_vfs_readpage_complete,
255 NULL,
256 GFP_KERNEL);
257 switch (ret) {
258 case -ENOBUFS:
259 case -ENODATA:
260 p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret);
261 return 1;
262 case 0:
263 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
264 return ret;
265 default:
266 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
267 return ret;
268 }
269 }
270
271 /**
272 * __v9fs_readpages_from_fscache - read multiple pages from cache
273 *
274 * Returns 0 if the pages are in cache and a BIO is submitted,
275 * 1 if the pages are not in cache and -error otherwise.
276 */
277
__v9fs_readpages_from_fscache(struct inode * inode,struct address_space * mapping,struct list_head * pages,unsigned * nr_pages)278 int __v9fs_readpages_from_fscache(struct inode *inode,
279 struct address_space *mapping,
280 struct list_head *pages,
281 unsigned *nr_pages)
282 {
283 int ret;
284 const struct v9fs_inode *v9inode = V9FS_I(inode);
285
286 p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages);
287 if (!v9inode->fscache)
288 return -ENOBUFS;
289
290 ret = fscache_read_or_alloc_pages(v9inode->fscache,
291 mapping, pages, nr_pages,
292 v9fs_vfs_readpage_complete,
293 NULL,
294 mapping_gfp_mask(mapping));
295 switch (ret) {
296 case -ENOBUFS:
297 case -ENODATA:
298 p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret);
299 return 1;
300 case 0:
301 BUG_ON(!list_empty(pages));
302 BUG_ON(*nr_pages != 0);
303 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
304 return ret;
305 default:
306 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
307 return ret;
308 }
309 }
310
311 /**
312 * __v9fs_readpage_to_fscache - write a page to the cache
313 *
314 */
315
__v9fs_readpage_to_fscache(struct inode * inode,struct page * page)316 void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
317 {
318 int ret;
319 const struct v9fs_inode *v9inode = V9FS_I(inode);
320
321 p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
322 ret = fscache_write_page(v9inode->fscache, page,
323 i_size_read(&v9inode->vfs_inode), GFP_KERNEL);
324 p9_debug(P9_DEBUG_FSC, "ret = %d\n", ret);
325 if (ret != 0)
326 v9fs_uncache_page(inode, page);
327 }
328
329 /*
330 * wait for a page to complete writing to the cache
331 */
__v9fs_fscache_wait_on_page_write(struct inode * inode,struct page * page)332 void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
333 {
334 const struct v9fs_inode *v9inode = V9FS_I(inode);
335 p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
336 if (PageFsCache(page))
337 fscache_wait_on_page_write(v9inode->fscache, page);
338 }
339