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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>
20
21#include "internal.h"
David Howells545db452009-04-03 16:42:44 +010022#include "iostat.h"
David Howells14727282009-04-03 16:42:42 +010023#include "fscache.h"
24
25#define NFSDBG_FACILITY NFSDBG_FSCACHE
26
David Howells08734042009-04-03 16:42:42 +010027static struct rb_root nfs_fscache_keys = RB_ROOT;
28static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
29
David Howells14727282009-04-03 16:42:42 +010030/*
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 */
36void 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 */
49void 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}
David Howells08734042009-04-03 16:42:42 +010057
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.
David Howells2df54802009-09-23 14:36:39 -040061 *
62 * The default uniquifier is just an empty string, but it may be overridden
63 * either by the 'fsc=xxx' option to mount, or by inheriting it from the parent
64 * superblock across an automount point of some nature.
David Howells08734042009-04-03 16:42:42 +010065 */
David Howells2df54802009-09-23 14:36:39 -040066void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq,
67 struct nfs_clone_mount *mntdata)
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;
David Howells08734042009-04-03 16:42:42 +010072 int diff, ulen;
73
David Howells2df54802009-09-23 14:36:39 -040074 if (uniq) {
75 ulen = strlen(uniq);
76 } else if (mntdata) {
77 struct nfs_server *mnt_s = NFS_SB(mntdata->sb);
78 if (mnt_s->fscache_key) {
79 uniq = mnt_s->fscache_key->key.uniquifier;
80 ulen = mnt_s->fscache_key->key.uniq_len;
81 }
82 }
83
84 if (!uniq) {
85 uniq = "";
86 ulen = 1;
87 }
88
David Howells08734042009-04-03 16:42:42 +010089 key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
90 if (!key)
91 return;
92
93 key->nfs_client = nfss->nfs_client;
94 key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
95 key->key.nfs_server.flags = nfss->flags;
96 key->key.nfs_server.rsize = nfss->rsize;
97 key->key.nfs_server.wsize = nfss->wsize;
98 key->key.nfs_server.acregmin = nfss->acregmin;
99 key->key.nfs_server.acregmax = nfss->acregmax;
100 key->key.nfs_server.acdirmin = nfss->acdirmin;
101 key->key.nfs_server.acdirmax = nfss->acdirmax;
102 key->key.nfs_server.fsid = nfss->fsid;
103 key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
104
105 key->key.uniq_len = ulen;
106 memcpy(key->key.uniquifier, uniq, ulen);
107
108 spin_lock(&nfs_fscache_keys_lock);
109 p = &nfs_fscache_keys.rb_node;
110 parent = NULL;
111 while (*p) {
112 parent = *p;
113 xkey = rb_entry(parent, struct nfs_fscache_key, node);
114
115 if (key->nfs_client < xkey->nfs_client)
116 goto go_left;
117 if (key->nfs_client > xkey->nfs_client)
118 goto go_right;
119
120 diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
121 if (diff < 0)
122 goto go_left;
123 if (diff > 0)
124 goto go_right;
125
126 if (key->key.uniq_len == 0)
127 goto non_unique;
128 diff = memcmp(key->key.uniquifier,
129 xkey->key.uniquifier,
130 key->key.uniq_len);
131 if (diff < 0)
132 goto go_left;
133 if (diff > 0)
134 goto go_right;
135 goto non_unique;
136
137 go_left:
138 p = &(*p)->rb_left;
139 continue;
140 go_right:
141 p = &(*p)->rb_right;
142 }
143
144 rb_link_node(&key->node, parent, p);
145 rb_insert_color(&key->node, &nfs_fscache_keys);
146 spin_unlock(&nfs_fscache_keys_lock);
147 nfss->fscache_key = key;
148
149 /* create a cache index for looking up filehandles */
150 nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
151 &nfs_fscache_super_index_def,
152 nfss);
153 dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
154 nfss, nfss->fscache);
155 return;
156
157non_unique:
158 spin_unlock(&nfs_fscache_keys_lock);
159 kfree(key);
160 nfss->fscache_key = NULL;
161 nfss->fscache = NULL;
162 printk(KERN_WARNING "NFS:"
163 " Cache request denied due to non-unique superblock keys\n");
164}
165
166/*
167 * release a per-superblock cookie
168 */
169void nfs_fscache_release_super_cookie(struct super_block *sb)
170{
171 struct nfs_server *nfss = NFS_SB(sb);
172
173 dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
174 nfss, nfss->fscache);
175
176 fscache_relinquish_cookie(nfss->fscache, 0);
177 nfss->fscache = NULL;
178
179 if (nfss->fscache_key) {
180 spin_lock(&nfs_fscache_keys_lock);
181 rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
182 spin_unlock(&nfs_fscache_keys_lock);
183 kfree(nfss->fscache_key);
184 nfss->fscache_key = NULL;
185 }
186}
David Howellsef79c092009-04-03 16:42:43 +0100187
188/*
189 * Initialise the per-inode cache cookie pointer for an NFS inode.
190 */
191void nfs_fscache_init_inode_cookie(struct inode *inode)
192{
193 NFS_I(inode)->fscache = NULL;
194 if (S_ISREG(inode->i_mode))
195 set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
196}
197
198/*
199 * Get the per-inode cache cookie for an NFS inode.
200 */
201static void nfs_fscache_enable_inode_cookie(struct inode *inode)
202{
203 struct super_block *sb = inode->i_sb;
204 struct nfs_inode *nfsi = NFS_I(inode);
205
206 if (nfsi->fscache || !NFS_FSCACHE(inode))
207 return;
208
209 if ((NFS_SB(sb)->options & NFS_OPTION_FSCACHE)) {
210 nfsi->fscache = fscache_acquire_cookie(
211 NFS_SB(sb)->fscache,
212 &nfs_fscache_inode_object_def,
213 nfsi);
214
215 dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
216 sb, nfsi, nfsi->fscache);
217 }
218}
219
220/*
221 * Release a per-inode cookie.
222 */
223void nfs_fscache_release_inode_cookie(struct inode *inode)
224{
225 struct nfs_inode *nfsi = NFS_I(inode);
226
227 dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
228 nfsi, nfsi->fscache);
229
230 fscache_relinquish_cookie(nfsi->fscache, 0);
231 nfsi->fscache = NULL;
232}
233
234/*
235 * Retire a per-inode cookie, destroying the data attached to it.
236 */
237void nfs_fscache_zap_inode_cookie(struct inode *inode)
238{
239 struct nfs_inode *nfsi = NFS_I(inode);
240
241 dfprintk(FSCACHE, "NFS: zapping cookie (0x%p/0x%p)\n",
242 nfsi, nfsi->fscache);
243
244 fscache_relinquish_cookie(nfsi->fscache, 1);
245 nfsi->fscache = NULL;
246}
247
248/*
249 * Turn off the cache with regard to a per-inode cookie if opened for writing,
250 * invalidating all the pages in the page cache relating to the associated
251 * inode to clear the per-page caching.
252 */
253static void nfs_fscache_disable_inode_cookie(struct inode *inode)
254{
255 clear_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
256
257 if (NFS_I(inode)->fscache) {
258 dfprintk(FSCACHE,
259 "NFS: nfsi 0x%p turning cache off\n", NFS_I(inode));
260
261 /* Need to invalidate any mapped pages that were read in before
262 * turning off the cache.
263 */
264 if (inode->i_mapping && inode->i_mapping->nrpages)
265 invalidate_inode_pages2(inode->i_mapping);
266
267 nfs_fscache_zap_inode_cookie(inode);
268 }
269}
270
271/*
272 * wait_on_bit() sleep function for uninterruptible waiting
273 */
274static int nfs_fscache_wait_bit(void *flags)
275{
276 schedule();
277 return 0;
278}
279
280/*
281 * Lock against someone else trying to also acquire or relinquish a cookie
282 */
283static inline void nfs_fscache_inode_lock(struct inode *inode)
284{
285 struct nfs_inode *nfsi = NFS_I(inode);
286
287 while (test_and_set_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags))
288 wait_on_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK,
289 nfs_fscache_wait_bit, TASK_UNINTERRUPTIBLE);
290}
291
292/*
293 * Unlock cookie management lock
294 */
295static inline void nfs_fscache_inode_unlock(struct inode *inode)
296{
297 struct nfs_inode *nfsi = NFS_I(inode);
298
299 smp_mb__before_clear_bit();
300 clear_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags);
301 smp_mb__after_clear_bit();
302 wake_up_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK);
303}
304
305/*
306 * Decide if we should enable or disable local caching for this inode.
307 * - For now, with NFS, only regular files that are open read-only will be able
308 * to use the cache.
309 * - May be invoked multiple times in parallel by parallel nfs_open() functions.
310 */
311void nfs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
312{
313 if (NFS_FSCACHE(inode)) {
314 nfs_fscache_inode_lock(inode);
315 if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
316 nfs_fscache_disable_inode_cookie(inode);
317 else
318 nfs_fscache_enable_inode_cookie(inode);
319 nfs_fscache_inode_unlock(inode);
320 }
321}
322
323/*
324 * Replace a per-inode cookie due to revalidation detecting a file having
325 * changed on the server.
326 */
327void nfs_fscache_reset_inode_cookie(struct inode *inode)
328{
329 struct nfs_inode *nfsi = NFS_I(inode);
330 struct nfs_server *nfss = NFS_SERVER(inode);
331 struct fscache_cookie *old = nfsi->fscache;
332
333 nfs_fscache_inode_lock(inode);
334 if (nfsi->fscache) {
335 /* retire the current fscache cache and get a new one */
336 fscache_relinquish_cookie(nfsi->fscache, 1);
337
338 nfsi->fscache = fscache_acquire_cookie(
339 nfss->nfs_client->fscache,
340 &nfs_fscache_inode_object_def,
341 nfsi);
342
343 dfprintk(FSCACHE,
344 "NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
345 nfss, nfsi, old, nfsi->fscache);
346 }
347 nfs_fscache_inode_unlock(inode);
348}
David Howells545db452009-04-03 16:42:44 +0100349
350/*
351 * Release the caching state associated with a page, if the page isn't busy
352 * interacting with the cache.
353 * - Returns true (can release page) or false (page busy).
354 */
355int nfs_fscache_release_page(struct page *page, gfp_t gfp)
356{
357 struct nfs_inode *nfsi = NFS_I(page->mapping->host);
358 struct fscache_cookie *cookie = nfsi->fscache;
359
360 BUG_ON(!cookie);
361
David Howells545db452009-04-03 16:42:44 +0100362 if (PageFsCache(page)) {
363 dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
364 cookie, page, nfsi);
365
David Howells201a1542009-11-19 18:11:35 +0000366 if (!fscache_maybe_release_page(cookie, page, gfp))
367 return 0;
368
David Howells545db452009-04-03 16:42:44 +0100369 nfs_add_fscache_stats(page->mapping->host,
370 NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
371 }
372
373 return 1;
374}
375
376/*
377 * Release the caching state associated with a page if undergoing complete page
378 * invalidation.
379 */
380void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
381{
382 struct nfs_inode *nfsi = NFS_I(inode);
383 struct fscache_cookie *cookie = nfsi->fscache;
384
385 BUG_ON(!cookie);
386
387 dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
388 cookie, page, nfsi);
389
390 fscache_wait_on_page_write(cookie, page);
391
392 BUG_ON(!PageLocked(page));
393 fscache_uncache_page(cookie, page);
394 nfs_add_fscache_stats(page->mapping->host,
395 NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
396}
David Howells9a9fc1c2009-04-03 16:42:44 +0100397
398/*
399 * Handle completion of a page being read from the cache.
400 * - Called in process (keventd) context.
401 */
402static void nfs_readpage_from_fscache_complete(struct page *page,
403 void *context,
404 int error)
405{
406 dfprintk(FSCACHE,
407 "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
408 page, context, error);
409
410 /* if the read completes with an error, we just unlock the page and let
411 * the VM reissue the readpage */
412 if (!error) {
413 SetPageUptodate(page);
414 unlock_page(page);
415 } else {
416 error = nfs_readpage_async(context, page->mapping->host, page);
417 if (error)
418 unlock_page(page);
419 }
420}
421
422/*
423 * Retrieve a page from fscache
424 */
425int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
426 struct inode *inode, struct page *page)
427{
428 int ret;
429
430 dfprintk(FSCACHE,
431 "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
432 NFS_I(inode)->fscache, page, page->index, page->flags, inode);
433
434 ret = fscache_read_or_alloc_page(NFS_I(inode)->fscache,
435 page,
436 nfs_readpage_from_fscache_complete,
437 ctx,
438 GFP_KERNEL);
439
440 switch (ret) {
441 case 0: /* read BIO submitted (page in fscache) */
442 dfprintk(FSCACHE,
443 "NFS: readpage_from_fscache: BIO submitted\n");
444 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK, 1);
445 return ret;
446
447 case -ENOBUFS: /* inode not in cache */
448 case -ENODATA: /* page not in cache */
449 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
450 dfprintk(FSCACHE,
451 "NFS: readpage_from_fscache %d\n", ret);
452 return 1;
453
454 default:
455 dfprintk(FSCACHE, "NFS: readpage_from_fscache %d\n", ret);
456 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
457 }
458 return ret;
459}
460
461/*
462 * Retrieve a set of pages from fscache
463 */
464int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
465 struct inode *inode,
466 struct address_space *mapping,
467 struct list_head *pages,
468 unsigned *nr_pages)
469{
470 int ret, npages = *nr_pages;
471
472 dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
473 NFS_I(inode)->fscache, npages, inode);
474
475 ret = fscache_read_or_alloc_pages(NFS_I(inode)->fscache,
476 mapping, pages, nr_pages,
477 nfs_readpage_from_fscache_complete,
478 ctx,
479 mapping_gfp_mask(mapping));
480 if (*nr_pages < npages)
481 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
482 npages);
483 if (*nr_pages > 0)
484 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
485 *nr_pages);
486
487 switch (ret) {
488 case 0: /* read submitted to the cache for all pages */
489 BUG_ON(!list_empty(pages));
490 BUG_ON(*nr_pages != 0);
491 dfprintk(FSCACHE,
492 "NFS: nfs_getpages_from_fscache: submitted\n");
493
494 return ret;
495
496 case -ENOBUFS: /* some pages aren't cached and can't be */
497 case -ENODATA: /* some pages aren't cached */
498 dfprintk(FSCACHE,
499 "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
500 return 1;
501
502 default:
503 dfprintk(FSCACHE,
504 "NFS: nfs_getpages_from_fscache: ret %d\n", ret);
505 }
506
507 return ret;
508}
David Howells7f8e05f2009-04-03 16:42:45 +0100509
510/*
511 * Store a newly fetched page in fscache
512 * - PG_fscache must be set on the page
513 */
514void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
515{
516 int ret;
517
518 dfprintk(FSCACHE,
519 "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
520 NFS_I(inode)->fscache, page, page->index, page->flags, sync);
521
522 ret = fscache_write_page(NFS_I(inode)->fscache, page, GFP_KERNEL);
523 dfprintk(FSCACHE,
524 "NFS: readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
525 page, page->index, page->flags, ret);
526
527 if (ret != 0) {
528 fscache_uncache_page(NFS_I(inode)->fscache, page);
529 nfs_add_fscache_stats(inode,
530 NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1);
531 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
532 } else {
533 nfs_add_fscache_stats(inode,
534 NFSIOS_FSCACHE_PAGES_WRITTEN_OK, 1);
535 }
536}