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David Howells14727282009-04-03 16:42:42 +01001/* 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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090020#include <linux/slab.h>
David Howells14727282009-04-03 16:42:42 +010021
22#include "internal.h"
David Howells545db452009-04-03 16:42:44 +010023#include "iostat.h"
David Howells14727282009-04-03 16:42:42 +010024#include "fscache.h"
25
26#define NFSDBG_FACILITY NFSDBG_FSCACHE
27
David Howells08734042009-04-03 16:42:42 +010028static struct rb_root nfs_fscache_keys = RB_ROOT;
29static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
30
David Howells14727282009-04-03 16:42:42 +010031/*
32 * Get the per-client index cookie for an NFS client if the appropriate mount
33 * flag was set
34 * - We always try and get an index cookie for the client, but get filehandle
35 * cookies on a per-superblock basis, depending on the mount flags
36 */
37void nfs_fscache_get_client_cookie(struct nfs_client *clp)
38{
39 /* create a cache index for looking up filehandles */
40 clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
41 &nfs_fscache_server_index_def,
42 clp);
43 dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
44 clp, clp->fscache);
45}
46
47/*
48 * Dispose of a per-client cookie
49 */
50void nfs_fscache_release_client_cookie(struct nfs_client *clp)
51{
52 dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
53 clp, clp->fscache);
54
55 fscache_relinquish_cookie(clp->fscache, 0);
56 clp->fscache = NULL;
57}
David Howells08734042009-04-03 16:42:42 +010058
59/*
60 * Get the cache cookie for an NFS superblock. We have to handle
61 * uniquification here because the cache doesn't do it for us.
David Howells2df54802009-09-23 14:36:39 -040062 *
63 * The default uniquifier is just an empty string, but it may be overridden
64 * either by the 'fsc=xxx' option to mount, or by inheriting it from the parent
65 * superblock across an automount point of some nature.
David Howells08734042009-04-03 16:42:42 +010066 */
Bryan Schumaker2311b942012-05-10 15:07:32 -040067void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int ulen)
David Howells08734042009-04-03 16:42:42 +010068{
69 struct nfs_fscache_key *key, *xkey;
70 struct nfs_server *nfss = NFS_SB(sb);
71 struct rb_node **p, *parent;
Bryan Schumaker2311b942012-05-10 15:07:32 -040072 int diff;
David Howells2df54802009-09-23 14:36:39 -040073
74 if (!uniq) {
75 uniq = "";
76 ulen = 1;
77 }
78
David Howells08734042009-04-03 16:42:42 +010079 key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
80 if (!key)
81 return;
82
83 key->nfs_client = nfss->nfs_client;
84 key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
85 key->key.nfs_server.flags = nfss->flags;
86 key->key.nfs_server.rsize = nfss->rsize;
87 key->key.nfs_server.wsize = nfss->wsize;
88 key->key.nfs_server.acregmin = nfss->acregmin;
89 key->key.nfs_server.acregmax = nfss->acregmax;
90 key->key.nfs_server.acdirmin = nfss->acdirmin;
91 key->key.nfs_server.acdirmax = nfss->acdirmax;
92 key->key.nfs_server.fsid = nfss->fsid;
93 key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
94
95 key->key.uniq_len = ulen;
96 memcpy(key->key.uniquifier, uniq, ulen);
97
98 spin_lock(&nfs_fscache_keys_lock);
99 p = &nfs_fscache_keys.rb_node;
100 parent = NULL;
101 while (*p) {
102 parent = *p;
103 xkey = rb_entry(parent, struct nfs_fscache_key, node);
104
105 if (key->nfs_client < xkey->nfs_client)
106 goto go_left;
107 if (key->nfs_client > xkey->nfs_client)
108 goto go_right;
109
110 diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
111 if (diff < 0)
112 goto go_left;
113 if (diff > 0)
114 goto go_right;
115
116 if (key->key.uniq_len == 0)
117 goto non_unique;
118 diff = memcmp(key->key.uniquifier,
119 xkey->key.uniquifier,
120 key->key.uniq_len);
121 if (diff < 0)
122 goto go_left;
123 if (diff > 0)
124 goto go_right;
125 goto non_unique;
126
127 go_left:
128 p = &(*p)->rb_left;
129 continue;
130 go_right:
131 p = &(*p)->rb_right;
132 }
133
134 rb_link_node(&key->node, parent, p);
135 rb_insert_color(&key->node, &nfs_fscache_keys);
136 spin_unlock(&nfs_fscache_keys_lock);
137 nfss->fscache_key = key;
138
139 /* create a cache index for looking up filehandles */
140 nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
141 &nfs_fscache_super_index_def,
142 nfss);
143 dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
144 nfss, nfss->fscache);
145 return;
146
147non_unique:
148 spin_unlock(&nfs_fscache_keys_lock);
149 kfree(key);
150 nfss->fscache_key = NULL;
151 nfss->fscache = NULL;
152 printk(KERN_WARNING "NFS:"
153 " Cache request denied due to non-unique superblock keys\n");
154}
155
156/*
157 * release a per-superblock cookie
158 */
159void nfs_fscache_release_super_cookie(struct super_block *sb)
160{
161 struct nfs_server *nfss = NFS_SB(sb);
162
163 dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
164 nfss, nfss->fscache);
165
166 fscache_relinquish_cookie(nfss->fscache, 0);
167 nfss->fscache = NULL;
168
169 if (nfss->fscache_key) {
170 spin_lock(&nfs_fscache_keys_lock);
171 rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
172 spin_unlock(&nfs_fscache_keys_lock);
173 kfree(nfss->fscache_key);
174 nfss->fscache_key = NULL;
175 }
176}
David Howellsef79c092009-04-03 16:42:43 +0100177
178/*
179 * Initialise the per-inode cache cookie pointer for an NFS inode.
180 */
181void nfs_fscache_init_inode_cookie(struct inode *inode)
182{
183 NFS_I(inode)->fscache = NULL;
184 if (S_ISREG(inode->i_mode))
185 set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
186}
187
188/*
189 * Get the per-inode cache cookie for an NFS inode.
190 */
191static void nfs_fscache_enable_inode_cookie(struct inode *inode)
192{
193 struct super_block *sb = inode->i_sb;
194 struct nfs_inode *nfsi = NFS_I(inode);
195
196 if (nfsi->fscache || !NFS_FSCACHE(inode))
197 return;
198
199 if ((NFS_SB(sb)->options & NFS_OPTION_FSCACHE)) {
200 nfsi->fscache = fscache_acquire_cookie(
201 NFS_SB(sb)->fscache,
202 &nfs_fscache_inode_object_def,
203 nfsi);
204
205 dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
206 sb, nfsi, nfsi->fscache);
207 }
208}
209
210/*
211 * Release a per-inode cookie.
212 */
213void nfs_fscache_release_inode_cookie(struct inode *inode)
214{
215 struct nfs_inode *nfsi = NFS_I(inode);
216
217 dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
218 nfsi, nfsi->fscache);
219
220 fscache_relinquish_cookie(nfsi->fscache, 0);
221 nfsi->fscache = NULL;
222}
223
224/*
225 * Retire a per-inode cookie, destroying the data attached to it.
226 */
227void nfs_fscache_zap_inode_cookie(struct inode *inode)
228{
229 struct nfs_inode *nfsi = NFS_I(inode);
230
231 dfprintk(FSCACHE, "NFS: zapping cookie (0x%p/0x%p)\n",
232 nfsi, nfsi->fscache);
233
234 fscache_relinquish_cookie(nfsi->fscache, 1);
235 nfsi->fscache = NULL;
236}
237
238/*
239 * Turn off the cache with regard to a per-inode cookie if opened for writing,
240 * invalidating all the pages in the page cache relating to the associated
241 * inode to clear the per-page caching.
242 */
243static void nfs_fscache_disable_inode_cookie(struct inode *inode)
244{
245 clear_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
246
247 if (NFS_I(inode)->fscache) {
248 dfprintk(FSCACHE,
249 "NFS: nfsi 0x%p turning cache off\n", NFS_I(inode));
250
David Howellsc902ce12011-07-07 12:19:48 +0100251 /* Need to uncache any pages attached to this inode that
252 * fscache knows about before turning off the cache.
David Howellsef79c092009-04-03 16:42:43 +0100253 */
David Howellsc902ce12011-07-07 12:19:48 +0100254 fscache_uncache_all_inode_pages(NFS_I(inode)->fscache, inode);
David Howellsef79c092009-04-03 16:42:43 +0100255 nfs_fscache_zap_inode_cookie(inode);
256 }
257}
258
259/*
260 * wait_on_bit() sleep function for uninterruptible waiting
261 */
262static int nfs_fscache_wait_bit(void *flags)
263{
264 schedule();
265 return 0;
266}
267
268/*
269 * Lock against someone else trying to also acquire or relinquish a cookie
270 */
271static inline void nfs_fscache_inode_lock(struct inode *inode)
272{
273 struct nfs_inode *nfsi = NFS_I(inode);
274
275 while (test_and_set_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags))
276 wait_on_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK,
277 nfs_fscache_wait_bit, TASK_UNINTERRUPTIBLE);
278}
279
280/*
281 * Unlock cookie management lock
282 */
283static inline void nfs_fscache_inode_unlock(struct inode *inode)
284{
285 struct nfs_inode *nfsi = NFS_I(inode);
286
287 smp_mb__before_clear_bit();
288 clear_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags);
289 smp_mb__after_clear_bit();
290 wake_up_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK);
291}
292
293/*
294 * Decide if we should enable or disable local caching for this inode.
295 * - For now, with NFS, only regular files that are open read-only will be able
296 * to use the cache.
297 * - May be invoked multiple times in parallel by parallel nfs_open() functions.
298 */
299void nfs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
300{
301 if (NFS_FSCACHE(inode)) {
302 nfs_fscache_inode_lock(inode);
303 if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
304 nfs_fscache_disable_inode_cookie(inode);
305 else
306 nfs_fscache_enable_inode_cookie(inode);
307 nfs_fscache_inode_unlock(inode);
308 }
309}
310
311/*
312 * Replace a per-inode cookie due to revalidation detecting a file having
313 * changed on the server.
314 */
315void nfs_fscache_reset_inode_cookie(struct inode *inode)
316{
317 struct nfs_inode *nfsi = NFS_I(inode);
318 struct nfs_server *nfss = NFS_SERVER(inode);
Trond Myklebust6f008662012-03-20 14:12:46 -0400319 NFS_IFDEBUG(struct fscache_cookie *old = nfsi->fscache);
David Howellsef79c092009-04-03 16:42:43 +0100320
321 nfs_fscache_inode_lock(inode);
322 if (nfsi->fscache) {
323 /* retire the current fscache cache and get a new one */
324 fscache_relinquish_cookie(nfsi->fscache, 1);
325
326 nfsi->fscache = fscache_acquire_cookie(
327 nfss->nfs_client->fscache,
328 &nfs_fscache_inode_object_def,
329 nfsi);
330
331 dfprintk(FSCACHE,
332 "NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
333 nfss, nfsi, old, nfsi->fscache);
334 }
335 nfs_fscache_inode_unlock(inode);
336}
David Howells545db452009-04-03 16:42:44 +0100337
338/*
339 * Release the caching state associated with a page, if the page isn't busy
340 * interacting with the cache.
341 * - Returns true (can release page) or false (page busy).
342 */
343int nfs_fscache_release_page(struct page *page, gfp_t gfp)
344{
David Howells545db452009-04-03 16:42:44 +0100345 if (PageFsCache(page)) {
Trond Myklebust2c174002010-02-08 09:32:27 -0500346 struct nfs_inode *nfsi = NFS_I(page->mapping->host);
347 struct fscache_cookie *cookie = nfsi->fscache;
348
349 BUG_ON(!cookie);
David Howells545db452009-04-03 16:42:44 +0100350 dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
351 cookie, page, nfsi);
352
David Howells201a1542009-11-19 18:11:35 +0000353 if (!fscache_maybe_release_page(cookie, page, gfp))
354 return 0;
355
David Howells545db452009-04-03 16:42:44 +0100356 nfs_add_fscache_stats(page->mapping->host,
357 NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
358 }
359
360 return 1;
361}
362
363/*
364 * Release the caching state associated with a page if undergoing complete page
365 * invalidation.
366 */
367void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
368{
369 struct nfs_inode *nfsi = NFS_I(inode);
370 struct fscache_cookie *cookie = nfsi->fscache;
371
372 BUG_ON(!cookie);
373
374 dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
375 cookie, page, nfsi);
376
377 fscache_wait_on_page_write(cookie, page);
378
379 BUG_ON(!PageLocked(page));
380 fscache_uncache_page(cookie, page);
381 nfs_add_fscache_stats(page->mapping->host,
382 NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
383}
David Howells9a9fc1c2009-04-03 16:42:44 +0100384
385/*
386 * Handle completion of a page being read from the cache.
387 * - Called in process (keventd) context.
388 */
389static void nfs_readpage_from_fscache_complete(struct page *page,
390 void *context,
391 int error)
392{
393 dfprintk(FSCACHE,
394 "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
395 page, context, error);
396
397 /* if the read completes with an error, we just unlock the page and let
398 * the VM reissue the readpage */
399 if (!error) {
400 SetPageUptodate(page);
401 unlock_page(page);
402 } else {
403 error = nfs_readpage_async(context, page->mapping->host, page);
404 if (error)
405 unlock_page(page);
406 }
407}
408
409/*
410 * Retrieve a page from fscache
411 */
412int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
413 struct inode *inode, struct page *page)
414{
415 int ret;
416
417 dfprintk(FSCACHE,
418 "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
419 NFS_I(inode)->fscache, page, page->index, page->flags, inode);
420
421 ret = fscache_read_or_alloc_page(NFS_I(inode)->fscache,
422 page,
423 nfs_readpage_from_fscache_complete,
424 ctx,
425 GFP_KERNEL);
426
427 switch (ret) {
428 case 0: /* read BIO submitted (page in fscache) */
429 dfprintk(FSCACHE,
430 "NFS: readpage_from_fscache: BIO submitted\n");
431 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK, 1);
432 return ret;
433
434 case -ENOBUFS: /* inode not in cache */
435 case -ENODATA: /* page not in cache */
436 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
437 dfprintk(FSCACHE,
438 "NFS: readpage_from_fscache %d\n", ret);
439 return 1;
440
441 default:
442 dfprintk(FSCACHE, "NFS: readpage_from_fscache %d\n", ret);
443 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
444 }
445 return ret;
446}
447
448/*
449 * Retrieve a set of pages from fscache
450 */
451int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
452 struct inode *inode,
453 struct address_space *mapping,
454 struct list_head *pages,
455 unsigned *nr_pages)
456{
Chuck Lever0f15c532010-05-07 13:33:48 -0400457 unsigned npages = *nr_pages;
458 int ret;
David Howells9a9fc1c2009-04-03 16:42:44 +0100459
460 dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
461 NFS_I(inode)->fscache, npages, inode);
462
463 ret = fscache_read_or_alloc_pages(NFS_I(inode)->fscache,
464 mapping, pages, nr_pages,
465 nfs_readpage_from_fscache_complete,
466 ctx,
467 mapping_gfp_mask(mapping));
468 if (*nr_pages < npages)
469 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
470 npages);
471 if (*nr_pages > 0)
472 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
473 *nr_pages);
474
475 switch (ret) {
476 case 0: /* read submitted to the cache for all pages */
477 BUG_ON(!list_empty(pages));
478 BUG_ON(*nr_pages != 0);
479 dfprintk(FSCACHE,
480 "NFS: nfs_getpages_from_fscache: submitted\n");
481
482 return ret;
483
484 case -ENOBUFS: /* some pages aren't cached and can't be */
485 case -ENODATA: /* some pages aren't cached */
486 dfprintk(FSCACHE,
487 "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
488 return 1;
489
490 default:
491 dfprintk(FSCACHE,
492 "NFS: nfs_getpages_from_fscache: ret %d\n", ret);
493 }
494
495 return ret;
496}
David Howells7f8e05f2009-04-03 16:42:45 +0100497
498/*
499 * Store a newly fetched page in fscache
500 * - PG_fscache must be set on the page
501 */
502void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
503{
504 int ret;
505
506 dfprintk(FSCACHE,
507 "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
508 NFS_I(inode)->fscache, page, page->index, page->flags, sync);
509
510 ret = fscache_write_page(NFS_I(inode)->fscache, page, GFP_KERNEL);
511 dfprintk(FSCACHE,
512 "NFS: readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
513 page, page->index, page->flags, ret);
514
515 if (ret != 0) {
516 fscache_uncache_page(NFS_I(inode)->fscache, page);
517 nfs_add_fscache_stats(inode,
518 NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1);
519 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
520 } else {
521 nfs_add_fscache_stats(inode,
522 NFSIOS_FSCACHE_PAGES_WRITTEN_OK, 1);
523 }
524}