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1/*
2 * V9FS cache definitions.
3 *
4 * Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2
8 * as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to:
17 * Free Software Foundation
18 * 51 Franklin Street, Fifth Floor
19 * Boston, MA 02111-1301 USA
20 *
21 */
22
23#include <linux/jiffies.h>
24#include <linux/file.h>
25#include <linux/slab.h>
26#include <linux/stat.h>
27#include <linux/sched.h>
28#include <linux/fs.h>
29#include <net/9p/9p.h>
30
31#include "v9fs.h"
32#include "cache.h"
33
34#define CACHETAG_LEN 11
35
36struct fscache_netfs v9fs_cache_netfs = {
37 .name = "9p",
38 .version = 0,
39};
40
41/**
42 * v9fs_random_cachetag - Generate a random tag to be associated
43 * with a new cache session.
44 *
45 * The value of jiffies is used for a fairly randomly cache tag.
46 */
47
48static
49int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
50{
51 v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);
52 if (!v9ses->cachetag)
53 return -ENOMEM;
54
55 return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
56}
57
58static uint16_t v9fs_cache_session_get_key(const void *cookie_netfs_data,
59 void *buffer, uint16_t bufmax)
60{
61 struct v9fs_session_info *v9ses;
62 uint16_t klen = 0;
63
64 v9ses = (struct v9fs_session_info *)cookie_netfs_data;
65 p9_debug(P9_DEBUG_FSC, "session %p buf %p size %u\n",
66 v9ses, buffer, bufmax);
67
68 if (v9ses->cachetag)
69 klen = strlen(v9ses->cachetag);
70
71 if (klen > bufmax)
72 return 0;
73
74 memcpy(buffer, v9ses->cachetag, klen);
75 p9_debug(P9_DEBUG_FSC, "cache session tag %s\n", v9ses->cachetag);
76 return klen;
77}
78
79const struct fscache_cookie_def v9fs_cache_session_index_def = {
80 .name = "9P.session",
81 .type = FSCACHE_COOKIE_TYPE_INDEX,
82 .get_key = v9fs_cache_session_get_key,
83};
84
85void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
86{
87 /* If no cache session tag was specified, we generate a random one. */
88 if (!v9ses->cachetag)
89 v9fs_random_cachetag(v9ses);
90
91 v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
92 &v9fs_cache_session_index_def,
93 v9ses);
94 p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
95 v9ses, v9ses->fscache);
96}
97
98void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
99{
100 p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",
101 v9ses, v9ses->fscache);
102 fscache_relinquish_cookie(v9ses->fscache, 0);
103 v9ses->fscache = NULL;
104}
105
106
107static uint16_t v9fs_cache_inode_get_key(const void *cookie_netfs_data,
108 void *buffer, uint16_t bufmax)
109{
110 const struct v9fs_inode *v9inode = cookie_netfs_data;
111 memcpy(buffer, &v9inode->qid.path, sizeof(v9inode->qid.path));
112 p9_debug(P9_DEBUG_FSC, "inode %p get key %llu\n",
113 &v9inode->vfs_inode, v9inode->qid.path);
114 return sizeof(v9inode->qid.path);
115}
116
117static void v9fs_cache_inode_get_attr(const void *cookie_netfs_data,
118 uint64_t *size)
119{
120 const struct v9fs_inode *v9inode = cookie_netfs_data;
121 *size = i_size_read(&v9inode->vfs_inode);
122
123 p9_debug(P9_DEBUG_FSC, "inode %p get attr %llu\n",
124 &v9inode->vfs_inode, *size);
125}
126
127static uint16_t v9fs_cache_inode_get_aux(const void *cookie_netfs_data,
128 void *buffer, uint16_t buflen)
129{
130 const struct v9fs_inode *v9inode = cookie_netfs_data;
131 memcpy(buffer, &v9inode->qid.version, sizeof(v9inode->qid.version));
132 p9_debug(P9_DEBUG_FSC, "inode %p get aux %u\n",
133 &v9inode->vfs_inode, v9inode->qid.version);
134 return sizeof(v9inode->qid.version);
135}
136
137static enum
138fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
139 const void *buffer,
140 uint16_t buflen)
141{
142 const struct v9fs_inode *v9inode = cookie_netfs_data;
143
144 if (buflen != sizeof(v9inode->qid.version))
145 return FSCACHE_CHECKAUX_OBSOLETE;
146
147 if (memcmp(buffer, &v9inode->qid.version,
148 sizeof(v9inode->qid.version)))
149 return FSCACHE_CHECKAUX_OBSOLETE;
150
151 return FSCACHE_CHECKAUX_OKAY;
152}
153
154static void v9fs_cache_inode_now_uncached(void *cookie_netfs_data)
155{
156 struct v9fs_inode *v9inode = cookie_netfs_data;
157 struct pagevec pvec;
158 pgoff_t first;
159 int loop, nr_pages;
160
161 pagevec_init(&pvec, 0);
162 first = 0;
163
164 for (;;) {
165 nr_pages = pagevec_lookup(&pvec, v9inode->vfs_inode.i_mapping,
166 first,
167 PAGEVEC_SIZE - pagevec_count(&pvec));
168 if (!nr_pages)
169 break;
170
171 for (loop = 0; loop < nr_pages; loop++)
172 ClearPageFsCache(pvec.pages[loop]);
173
174 first = pvec.pages[nr_pages - 1]->index + 1;
175
176 pvec.nr = nr_pages;
177 pagevec_release(&pvec);
178 cond_resched();
179 }
180}
181
182const struct fscache_cookie_def v9fs_cache_inode_index_def = {
183 .name = "9p.inode",
184 .type = FSCACHE_COOKIE_TYPE_DATAFILE,
185 .get_key = v9fs_cache_inode_get_key,
186 .get_attr = v9fs_cache_inode_get_attr,
187 .get_aux = v9fs_cache_inode_get_aux,
188 .check_aux = v9fs_cache_inode_check_aux,
189 .now_uncached = v9fs_cache_inode_now_uncached,
190};
191
192void v9fs_cache_inode_get_cookie(struct inode *inode)
193{
194 struct v9fs_inode *v9inode;
195 struct v9fs_session_info *v9ses;
196
197 if (!S_ISREG(inode->i_mode))
198 return;
199
200 v9inode = V9FS_I(inode);
201 if (v9inode->fscache)
202 return;
203
204 v9ses = v9fs_inode2v9ses(inode);
205 v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
206 &v9fs_cache_inode_index_def,
207 v9inode);
208
209 p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
210 inode, v9inode->fscache);
211}
212
213void v9fs_cache_inode_put_cookie(struct inode *inode)
214{
215 struct v9fs_inode *v9inode = V9FS_I(inode);
216
217 if (!v9inode->fscache)
218 return;
219 p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
220 inode, v9inode->fscache);
221
222 fscache_relinquish_cookie(v9inode->fscache, 0);
223 v9inode->fscache = NULL;
224}
225
226void v9fs_cache_inode_flush_cookie(struct inode *inode)
227{
228 struct v9fs_inode *v9inode = V9FS_I(inode);
229
230 if (!v9inode->fscache)
231 return;
232 p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
233 inode, v9inode->fscache);
234
235 fscache_relinquish_cookie(v9inode->fscache, 1);
236 v9inode->fscache = NULL;
237}
238
239void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
240{
241 struct v9fs_inode *v9inode = V9FS_I(inode);
242 struct p9_fid *fid;
243
244 if (!v9inode->fscache)
245 return;
246
247 spin_lock(&v9inode->fscache_lock);
248 fid = filp->private_data;
249 if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
250 v9fs_cache_inode_flush_cookie(inode);
251 else
252 v9fs_cache_inode_get_cookie(inode);
253
254 spin_unlock(&v9inode->fscache_lock);
255}
256
257void v9fs_cache_inode_reset_cookie(struct inode *inode)
258{
259 struct v9fs_inode *v9inode = V9FS_I(inode);
260 struct v9fs_session_info *v9ses;
261 struct fscache_cookie *old;
262
263 if (!v9inode->fscache)
264 return;
265
266 old = v9inode->fscache;
267
268 spin_lock(&v9inode->fscache_lock);
269 fscache_relinquish_cookie(v9inode->fscache, 1);
270
271 v9ses = v9fs_inode2v9ses(inode);
272 v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
273 &v9fs_cache_inode_index_def,
274 v9inode);
275 p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
276 inode, old, v9inode->fscache);
277
278 spin_unlock(&v9inode->fscache_lock);
279}
280
281int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
282{
283 struct inode *inode = page->mapping->host;
284 struct v9fs_inode *v9inode = V9FS_I(inode);
285
286 BUG_ON(!v9inode->fscache);
287
288 return fscache_maybe_release_page(v9inode->fscache, page, gfp);
289}
290
291void __v9fs_fscache_invalidate_page(struct page *page)
292{
293 struct inode *inode = page->mapping->host;
294 struct v9fs_inode *v9inode = V9FS_I(inode);
295
296 BUG_ON(!v9inode->fscache);
297
298 if (PageFsCache(page)) {
299 fscache_wait_on_page_write(v9inode->fscache, page);
300 BUG_ON(!PageLocked(page));
301 fscache_uncache_page(v9inode->fscache, page);
302 }
303}
304
305static void v9fs_vfs_readpage_complete(struct page *page, void *data,
306 int error)
307{
308 if (!error)
309 SetPageUptodate(page);
310
311 unlock_page(page);
312}
313
314/**
315 * __v9fs_readpage_from_fscache - read a page from cache
316 *
317 * Returns 0 if the pages are in cache and a BIO is submitted,
318 * 1 if the pages are not in cache and -error otherwise.
319 */
320
321int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
322{
323 int ret;
324 const struct v9fs_inode *v9inode = V9FS_I(inode);
325
326 p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
327 if (!v9inode->fscache)
328 return -ENOBUFS;
329
330 ret = fscache_read_or_alloc_page(v9inode->fscache,
331 page,
332 v9fs_vfs_readpage_complete,
333 NULL,
334 GFP_KERNEL);
335 switch (ret) {
336 case -ENOBUFS:
337 case -ENODATA:
338 p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret);
339 return 1;
340 case 0:
341 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
342 return ret;
343 default:
344 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
345 return ret;
346 }
347}
348
349/**
350 * __v9fs_readpages_from_fscache - read multiple pages from cache
351 *
352 * Returns 0 if the pages are in cache and a BIO is submitted,
353 * 1 if the pages are not in cache and -error otherwise.
354 */
355
356int __v9fs_readpages_from_fscache(struct inode *inode,
357 struct address_space *mapping,
358 struct list_head *pages,
359 unsigned *nr_pages)
360{
361 int ret;
362 const struct v9fs_inode *v9inode = V9FS_I(inode);
363
364 p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages);
365 if (!v9inode->fscache)
366 return -ENOBUFS;
367
368 ret = fscache_read_or_alloc_pages(v9inode->fscache,
369 mapping, pages, nr_pages,
370 v9fs_vfs_readpage_complete,
371 NULL,
372 mapping_gfp_mask(mapping));
373 switch (ret) {
374 case -ENOBUFS:
375 case -ENODATA:
376 p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret);
377 return 1;
378 case 0:
379 BUG_ON(!list_empty(pages));
380 BUG_ON(*nr_pages != 0);
381 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
382 return ret;
383 default:
384 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
385 return ret;
386 }
387}
388
389/**
390 * __v9fs_readpage_to_fscache - write a page to the cache
391 *
392 */
393
394void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
395{
396 int ret;
397 const struct v9fs_inode *v9inode = V9FS_I(inode);
398
399 p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
400 ret = fscache_write_page(v9inode->fscache, page, GFP_KERNEL);
401 p9_debug(P9_DEBUG_FSC, "ret = %d\n", ret);
402 if (ret != 0)
403 v9fs_uncache_page(inode, page);
404}
405
406/*
407 * wait for a page to complete writing to the cache
408 */
409void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
410{
411 const struct v9fs_inode *v9inode = V9FS_I(inode);
412 p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
413 if (PageFsCache(page))
414 fscache_wait_on_page_write(v9inode->fscache, page);
415}