1 /* NFS filesystem cache interface
2 *
3 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12 #include <linux/init.h>
13 #include <linux/kernel.h>
14 #include <linux/sched.h>
15 #include <linux/mm.h>
16 #include <linux/nfs_fs.h>
17 #include <linux/nfs_fs_sb.h>
18 #include <linux/in6.h>
19 #include <linux/seq_file.h>
20
21 #include "internal.h"
22 #include "iostat.h"
23 #include "fscache.h"
24
25 #define NFSDBG_FACILITY NFSDBG_FSCACHE
26
27 static struct rb_root nfs_fscache_keys = RB_ROOT;
28 static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
29
30 /*
31 * Get the per-client index cookie for an NFS client if the appropriate mount
32 * flag was set
33 * - We always try and get an index cookie for the client, but get filehandle
34 * cookies on a per-superblock basis, depending on the mount flags
35 */
36 void nfs_fscache_get_client_cookie(struct nfs_client *clp)
37 {
38 /* create a cache index for looking up filehandles */
39 clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
40 &nfs_fscache_server_index_def,
41 clp);
42 dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
43 clp, clp->fscache);
44 }
45
46 /*
47 * Dispose of a per-client cookie
48 */
49 void nfs_fscache_release_client_cookie(struct nfs_client *clp)
50 {
51 dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
52 clp, clp->fscache);
53
54 fscache_relinquish_cookie(clp->fscache, 0);
55 clp->fscache = NULL;
56 }
57
58 /*
59 * Get the cache cookie for an NFS superblock. We have to handle
60 * uniquification here because the cache doesn't do it for us.
61 */
62 void nfs_fscache_get_super_cookie(struct super_block *sb,
63 struct nfs_parsed_mount_data *data)
64 {
65 struct nfs_fscache_key *key, *xkey;
66 struct nfs_server *nfss = NFS_SB(sb);
67 struct rb_node **p, *parent;
68 const char *uniq = data->fscache_uniq ?: "";
69 int diff, ulen;
70
71 ulen = strlen(uniq);
72 key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
73 if (!key)
74 return;
75
76 key->nfs_client = nfss->nfs_client;
77 key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
78 key->key.nfs_server.flags = nfss->flags;
79 key->key.nfs_server.rsize = nfss->rsize;
80 key->key.nfs_server.wsize = nfss->wsize;
81 key->key.nfs_server.acregmin = nfss->acregmin;
82 key->key.nfs_server.acregmax = nfss->acregmax;
83 key->key.nfs_server.acdirmin = nfss->acdirmin;
84 key->key.nfs_server.acdirmax = nfss->acdirmax;
85 key->key.nfs_server.fsid = nfss->fsid;
86 key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
87
88 key->key.uniq_len = ulen;
89 memcpy(key->key.uniquifier, uniq, ulen);
90
91 spin_lock(&nfs_fscache_keys_lock);
92 p = &nfs_fscache_keys.rb_node;
93 parent = NULL;
94 while (*p) {
95 parent = *p;
96 xkey = rb_entry(parent, struct nfs_fscache_key, node);
97
98 if (key->nfs_client < xkey->nfs_client)
99 goto go_left;
100 if (key->nfs_client > xkey->nfs_client)
101 goto go_right;
102
103 diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
104 if (diff < 0)
105 goto go_left;
106 if (diff > 0)
107 goto go_right;
108
109 if (key->key.uniq_len == 0)
110 goto non_unique;
111 diff = memcmp(key->key.uniquifier,
112 xkey->key.uniquifier,
113 key->key.uniq_len);
114 if (diff < 0)
115 goto go_left;
116 if (diff > 0)
117 goto go_right;
118 goto non_unique;
119
120 go_left:
121 p = &(*p)->rb_left;
122 continue;
123 go_right:
124 p = &(*p)->rb_right;
125 }
126
127 rb_link_node(&key->node, parent, p);
128 rb_insert_color(&key->node, &nfs_fscache_keys);
129 spin_unlock(&nfs_fscache_keys_lock);
130 nfss->fscache_key = key;
131
132 /* create a cache index for looking up filehandles */
133 nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
134 &nfs_fscache_super_index_def,
135 nfss);
136 dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
137 nfss, nfss->fscache);
138 return;
139
140 non_unique:
141 spin_unlock(&nfs_fscache_keys_lock);
142 kfree(key);
143 nfss->fscache_key = NULL;
144 nfss->fscache = NULL;
145 printk(KERN_WARNING "NFS:"
146 " Cache request denied due to non-unique superblock keys\n");
147 }
148
149 /*
150 * release a per-superblock cookie
151 */
152 void nfs_fscache_release_super_cookie(struct super_block *sb)
153 {
154 struct nfs_server *nfss = NFS_SB(sb);
155
156 dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
157 nfss, nfss->fscache);
158
159 fscache_relinquish_cookie(nfss->fscache, 0);
160 nfss->fscache = NULL;
161
162 if (nfss->fscache_key) {
163 spin_lock(&nfs_fscache_keys_lock);
164 rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
165 spin_unlock(&nfs_fscache_keys_lock);
166 kfree(nfss->fscache_key);
167 nfss->fscache_key = NULL;
168 }
169 }
170
171 /*
172 * Initialise the per-inode cache cookie pointer for an NFS inode.
173 */
174 void nfs_fscache_init_inode_cookie(struct inode *inode)
175 {
176 NFS_I(inode)->fscache = NULL;
177 if (S_ISREG(inode->i_mode))
178 set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
179 }
180
181 /*
182 * Get the per-inode cache cookie for an NFS inode.
183 */
184 static void nfs_fscache_enable_inode_cookie(struct inode *inode)
185 {
186 struct super_block *sb = inode->i_sb;
187 struct nfs_inode *nfsi = NFS_I(inode);
188
189 if (nfsi->fscache || !NFS_FSCACHE(inode))
190 return;
191
192 if ((NFS_SB(sb)->options & NFS_OPTION_FSCACHE)) {
193 nfsi->fscache = fscache_acquire_cookie(
194 NFS_SB(sb)->fscache,
195 &nfs_fscache_inode_object_def,
196 nfsi);
197
198 dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
199 sb, nfsi, nfsi->fscache);
200 }
201 }
202
203 /*
204 * Release a per-inode cookie.
205 */
206 void nfs_fscache_release_inode_cookie(struct inode *inode)
207 {
208 struct nfs_inode *nfsi = NFS_I(inode);
209
210 dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
211 nfsi, nfsi->fscache);
212
213 fscache_relinquish_cookie(nfsi->fscache, 0);
214 nfsi->fscache = NULL;
215 }
216
217 /*
218 * Retire a per-inode cookie, destroying the data attached to it.
219 */
220 void nfs_fscache_zap_inode_cookie(struct inode *inode)
221 {
222 struct nfs_inode *nfsi = NFS_I(inode);
223
224 dfprintk(FSCACHE, "NFS: zapping cookie (0x%p/0x%p)\n",
225 nfsi, nfsi->fscache);
226
227 fscache_relinquish_cookie(nfsi->fscache, 1);
228 nfsi->fscache = NULL;
229 }
230
231 /*
232 * Turn off the cache with regard to a per-inode cookie if opened for writing,
233 * invalidating all the pages in the page cache relating to the associated
234 * inode to clear the per-page caching.
235 */
236 static void nfs_fscache_disable_inode_cookie(struct inode *inode)
237 {
238 clear_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
239
240 if (NFS_I(inode)->fscache) {
241 dfprintk(FSCACHE,
242 "NFS: nfsi 0x%p turning cache off\n", NFS_I(inode));
243
244 /* Need to invalidate any mapped pages that were read in before
245 * turning off the cache.
246 */
247 if (inode->i_mapping && inode->i_mapping->nrpages)
248 invalidate_inode_pages2(inode->i_mapping);
249
250 nfs_fscache_zap_inode_cookie(inode);
251 }
252 }
253
254 /*
255 * wait_on_bit() sleep function for uninterruptible waiting
256 */
257 static int nfs_fscache_wait_bit(void *flags)
258 {
259 schedule();
260 return 0;
261 }
262
263 /*
264 * Lock against someone else trying to also acquire or relinquish a cookie
265 */
266 static inline void nfs_fscache_inode_lock(struct inode *inode)
267 {
268 struct nfs_inode *nfsi = NFS_I(inode);
269
270 while (test_and_set_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags))
271 wait_on_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK,
272 nfs_fscache_wait_bit, TASK_UNINTERRUPTIBLE);
273 }
274
275 /*
276 * Unlock cookie management lock
277 */
278 static inline void nfs_fscache_inode_unlock(struct inode *inode)
279 {
280 struct nfs_inode *nfsi = NFS_I(inode);
281
282 smp_mb__before_clear_bit();
283 clear_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags);
284 smp_mb__after_clear_bit();
285 wake_up_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK);
286 }
287
288 /*
289 * Decide if we should enable or disable local caching for this inode.
290 * - For now, with NFS, only regular files that are open read-only will be able
291 * to use the cache.
292 * - May be invoked multiple times in parallel by parallel nfs_open() functions.
293 */
294 void nfs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
295 {
296 if (NFS_FSCACHE(inode)) {
297 nfs_fscache_inode_lock(inode);
298 if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
299 nfs_fscache_disable_inode_cookie(inode);
300 else
301 nfs_fscache_enable_inode_cookie(inode);
302 nfs_fscache_inode_unlock(inode);
303 }
304 }
305
306 /*
307 * Replace a per-inode cookie due to revalidation detecting a file having
308 * changed on the server.
309 */
310 void nfs_fscache_reset_inode_cookie(struct inode *inode)
311 {
312 struct nfs_inode *nfsi = NFS_I(inode);
313 struct nfs_server *nfss = NFS_SERVER(inode);
314 struct fscache_cookie *old = nfsi->fscache;
315
316 nfs_fscache_inode_lock(inode);
317 if (nfsi->fscache) {
318 /* retire the current fscache cache and get a new one */
319 fscache_relinquish_cookie(nfsi->fscache, 1);
320
321 nfsi->fscache = fscache_acquire_cookie(
322 nfss->nfs_client->fscache,
323 &nfs_fscache_inode_object_def,
324 nfsi);
325
326 dfprintk(FSCACHE,
327 "NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
328 nfss, nfsi, old, nfsi->fscache);
329 }
330 nfs_fscache_inode_unlock(inode);
331 }
332
333 /*
334 * Release the caching state associated with a page, if the page isn't busy
335 * interacting with the cache.
336 * - Returns true (can release page) or false (page busy).
337 */
338 int nfs_fscache_release_page(struct page *page, gfp_t gfp)
339 {
340 if (PageFsCache(page)) {
341 struct nfs_inode *nfsi = NFS_I(page->mapping->host);
342 struct fscache_cookie *cookie = nfsi->fscache;
343
344 BUG_ON(!cookie);
345 dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
346 cookie, page, nfsi);
347
348 if (fscache_check_page_write(cookie, page)) {
349 if (!(gfp & __GFP_WAIT))
350 return 0;
351 fscache_wait_on_page_write(cookie, page);
352 }
353
354 fscache_uncache_page(cookie, page);
355 nfs_add_fscache_stats(page->mapping->host,
356 NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
357 }
358
359 return 1;
360 }
361
362 /*
363 * Release the caching state associated with a page if undergoing complete page
364 * invalidation.
365 */
366 void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
367 {
368 struct nfs_inode *nfsi = NFS_I(inode);
369 struct fscache_cookie *cookie = nfsi->fscache;
370
371 BUG_ON(!cookie);
372
373 dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
374 cookie, page, nfsi);
375
376 fscache_wait_on_page_write(cookie, page);
377
378 BUG_ON(!PageLocked(page));
379 fscache_uncache_page(cookie, page);
380 nfs_add_fscache_stats(page->mapping->host,
381 NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
382 }
383
384 /*
385 * Handle completion of a page being read from the cache.
386 * - Called in process (keventd) context.
387 */
388 static void nfs_readpage_from_fscache_complete(struct page *page,
389 void *context,
390 int error)
391 {
392 dfprintk(FSCACHE,
393 "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
394 page, context, error);
395
396 /* if the read completes with an error, we just unlock the page and let
397 * the VM reissue the readpage */
398 if (!error) {
399 SetPageUptodate(page);
400 unlock_page(page);
401 } else {
402 error = nfs_readpage_async(context, page->mapping->host, page);
403 if (error)
404 unlock_page(page);
405 }
406 }
407
408 /*
409 * Retrieve a page from fscache
410 */
411 int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
412 struct inode *inode, struct page *page)
413 {
414 int ret;
415
416 dfprintk(FSCACHE,
417 "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
418 NFS_I(inode)->fscache, page, page->index, page->flags, inode);
419
420 ret = fscache_read_or_alloc_page(NFS_I(inode)->fscache,
421 page,
422 nfs_readpage_from_fscache_complete,
423 ctx,
424 GFP_KERNEL);
425
426 switch (ret) {
427 case 0: /* read BIO submitted (page in fscache) */
428 dfprintk(FSCACHE,
429 "NFS: readpage_from_fscache: BIO submitted\n");
430 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK, 1);
431 return ret;
432
433 case -ENOBUFS: /* inode not in cache */
434 case -ENODATA: /* page not in cache */
435 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
436 dfprintk(FSCACHE,
437 "NFS: readpage_from_fscache %d\n", ret);
438 return 1;
439
440 default:
441 dfprintk(FSCACHE, "NFS: readpage_from_fscache %d\n", ret);
442 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
443 }
444 return ret;
445 }
446
447 /*
448 * Retrieve a set of pages from fscache
449 */
450 int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
451 struct inode *inode,
452 struct address_space *mapping,
453 struct list_head *pages,
454 unsigned *nr_pages)
455 {
456 int ret, npages = *nr_pages;
457
458 dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
459 NFS_I(inode)->fscache, npages, inode);
460
461 ret = fscache_read_or_alloc_pages(NFS_I(inode)->fscache,
462 mapping, pages, nr_pages,
463 nfs_readpage_from_fscache_complete,
464 ctx,
465 mapping_gfp_mask(mapping));
466 if (*nr_pages < npages)
467 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
468 npages);
469 if (*nr_pages > 0)
470 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
471 *nr_pages);
472
473 switch (ret) {
474 case 0: /* read submitted to the cache for all pages */
475 BUG_ON(!list_empty(pages));
476 BUG_ON(*nr_pages != 0);
477 dfprintk(FSCACHE,
478 "NFS: nfs_getpages_from_fscache: submitted\n");
479
480 return ret;
481
482 case -ENOBUFS: /* some pages aren't cached and can't be */
483 case -ENODATA: /* some pages aren't cached */
484 dfprintk(FSCACHE,
485 "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
486 return 1;
487
488 default:
489 dfprintk(FSCACHE,
490 "NFS: nfs_getpages_from_fscache: ret %d\n", ret);
491 }
492
493 return ret;
494 }
495
496 /*
497 * Store a newly fetched page in fscache
498 * - PG_fscache must be set on the page
499 */
500 void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
501 {
502 int ret;
503
504 dfprintk(FSCACHE,
505 "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
506 NFS_I(inode)->fscache, page, page->index, page->flags, sync);
507
508 ret = fscache_write_page(NFS_I(inode)->fscache, page, GFP_KERNEL);
509 dfprintk(FSCACHE,
510 "NFS: readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
511 page, page->index, page->flags, ret);
512
513 if (ret != 0) {
514 fscache_uncache_page(NFS_I(inode)->fscache, page);
515 nfs_add_fscache_stats(inode,
516 NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1);
517 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
518 } else {
519 nfs_add_fscache_stats(inode,
520 NFSIOS_FSCACHE_PAGES_WRITTEN_OK, 1);
521 }
522 }
523
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