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14727281
DH
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>
5a0e3ad6 20#include <linux/slab.h>
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21
22#include "internal.h"
545db45f 23#include "iostat.h"
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DH
24#include "fscache.h"
25
26#define NFSDBG_FACILITY NFSDBG_FSCACHE
27
08734048
DH
28static struct rb_root nfs_fscache_keys = RB_ROOT;
29static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
30
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DH
31/*
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}
08734048
DH
58
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.
2df54806
DH
62 *
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.
08734048 66 */
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DH
67void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq,
68 struct nfs_clone_mount *mntdata)
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DH
69{
70 struct nfs_fscache_key *key, *xkey;
71 struct nfs_server *nfss = NFS_SB(sb);
72 struct rb_node **p, *parent;
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DH
73 int diff, ulen;
74
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DH
75 if (uniq) {
76 ulen = strlen(uniq);
77 } else if (mntdata) {
78 struct nfs_server *mnt_s = NFS_SB(mntdata->sb);
79 if (mnt_s->fscache_key) {
80 uniq = mnt_s->fscache_key->key.uniquifier;
81 ulen = mnt_s->fscache_key->key.uniq_len;
82 }
83 }
84
85 if (!uniq) {
86 uniq = "";
87 ulen = 1;
88 }
89
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DH
90 key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
91 if (!key)
92 return;
93
94 key->nfs_client = nfss->nfs_client;
95 key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
96 key->key.nfs_server.flags = nfss->flags;
97 key->key.nfs_server.rsize = nfss->rsize;
98 key->key.nfs_server.wsize = nfss->wsize;
99 key->key.nfs_server.acregmin = nfss->acregmin;
100 key->key.nfs_server.acregmax = nfss->acregmax;
101 key->key.nfs_server.acdirmin = nfss->acdirmin;
102 key->key.nfs_server.acdirmax = nfss->acdirmax;
103 key->key.nfs_server.fsid = nfss->fsid;
104 key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
105
106 key->key.uniq_len = ulen;
107 memcpy(key->key.uniquifier, uniq, ulen);
108
109 spin_lock(&nfs_fscache_keys_lock);
110 p = &nfs_fscache_keys.rb_node;
111 parent = NULL;
112 while (*p) {
113 parent = *p;
114 xkey = rb_entry(parent, struct nfs_fscache_key, node);
115
116 if (key->nfs_client < xkey->nfs_client)
117 goto go_left;
118 if (key->nfs_client > xkey->nfs_client)
119 goto go_right;
120
121 diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
122 if (diff < 0)
123 goto go_left;
124 if (diff > 0)
125 goto go_right;
126
127 if (key->key.uniq_len == 0)
128 goto non_unique;
129 diff = memcmp(key->key.uniquifier,
130 xkey->key.uniquifier,
131 key->key.uniq_len);
132 if (diff < 0)
133 goto go_left;
134 if (diff > 0)
135 goto go_right;
136 goto non_unique;
137
138 go_left:
139 p = &(*p)->rb_left;
140 continue;
141 go_right:
142 p = &(*p)->rb_right;
143 }
144
145 rb_link_node(&key->node, parent, p);
146 rb_insert_color(&key->node, &nfs_fscache_keys);
147 spin_unlock(&nfs_fscache_keys_lock);
148 nfss->fscache_key = key;
149
150 /* create a cache index for looking up filehandles */
151 nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
152 &nfs_fscache_super_index_def,
153 nfss);
154 dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
155 nfss, nfss->fscache);
156 return;
157
158non_unique:
159 spin_unlock(&nfs_fscache_keys_lock);
160 kfree(key);
161 nfss->fscache_key = NULL;
162 nfss->fscache = NULL;
163 printk(KERN_WARNING "NFS:"
164 " Cache request denied due to non-unique superblock keys\n");
165}
166
167/*
168 * release a per-superblock cookie
169 */
170void nfs_fscache_release_super_cookie(struct super_block *sb)
171{
172 struct nfs_server *nfss = NFS_SB(sb);
173
174 dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
175 nfss, nfss->fscache);
176
177 fscache_relinquish_cookie(nfss->fscache, 0);
178 nfss->fscache = NULL;
179
180 if (nfss->fscache_key) {
181 spin_lock(&nfs_fscache_keys_lock);
182 rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
183 spin_unlock(&nfs_fscache_keys_lock);
184 kfree(nfss->fscache_key);
185 nfss->fscache_key = NULL;
186 }
187}
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DH
188
189/*
190 * Initialise the per-inode cache cookie pointer for an NFS inode.
191 */
192void nfs_fscache_init_inode_cookie(struct inode *inode)
193{
194 NFS_I(inode)->fscache = NULL;
195 if (S_ISREG(inode->i_mode))
196 set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
197}
198
199/*
200 * Get the per-inode cache cookie for an NFS inode.
201 */
202static void nfs_fscache_enable_inode_cookie(struct inode *inode)
203{
204 struct super_block *sb = inode->i_sb;
205 struct nfs_inode *nfsi = NFS_I(inode);
206
207 if (nfsi->fscache || !NFS_FSCACHE(inode))
208 return;
209
210 if ((NFS_SB(sb)->options & NFS_OPTION_FSCACHE)) {
211 nfsi->fscache = fscache_acquire_cookie(
212 NFS_SB(sb)->fscache,
213 &nfs_fscache_inode_object_def,
214 nfsi);
215
216 dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
217 sb, nfsi, nfsi->fscache);
218 }
219}
220
221/*
222 * Release a per-inode cookie.
223 */
224void nfs_fscache_release_inode_cookie(struct inode *inode)
225{
226 struct nfs_inode *nfsi = NFS_I(inode);
227
228 dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
229 nfsi, nfsi->fscache);
230
231 fscache_relinquish_cookie(nfsi->fscache, 0);
232 nfsi->fscache = NULL;
233}
234
235/*
236 * Retire a per-inode cookie, destroying the data attached to it.
237 */
238void nfs_fscache_zap_inode_cookie(struct inode *inode)
239{
240 struct nfs_inode *nfsi = NFS_I(inode);
241
242 dfprintk(FSCACHE, "NFS: zapping cookie (0x%p/0x%p)\n",
243 nfsi, nfsi->fscache);
244
245 fscache_relinquish_cookie(nfsi->fscache, 1);
246 nfsi->fscache = NULL;
247}
248
249/*
250 * Turn off the cache with regard to a per-inode cookie if opened for writing,
251 * invalidating all the pages in the page cache relating to the associated
252 * inode to clear the per-page caching.
253 */
254static void nfs_fscache_disable_inode_cookie(struct inode *inode)
255{
256 clear_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
257
258 if (NFS_I(inode)->fscache) {
259 dfprintk(FSCACHE,
260 "NFS: nfsi 0x%p turning cache off\n", NFS_I(inode));
261
262 /* Need to invalidate any mapped pages that were read in before
263 * turning off the cache.
264 */
265 if (inode->i_mapping && inode->i_mapping->nrpages)
266 invalidate_inode_pages2(inode->i_mapping);
267
268 nfs_fscache_zap_inode_cookie(inode);
269 }
270}
271
272/*
273 * wait_on_bit() sleep function for uninterruptible waiting
274 */
275static int nfs_fscache_wait_bit(void *flags)
276{
277 schedule();
278 return 0;
279}
280
281/*
282 * Lock against someone else trying to also acquire or relinquish a cookie
283 */
284static inline void nfs_fscache_inode_lock(struct inode *inode)
285{
286 struct nfs_inode *nfsi = NFS_I(inode);
287
288 while (test_and_set_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags))
289 wait_on_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK,
290 nfs_fscache_wait_bit, TASK_UNINTERRUPTIBLE);
291}
292
293/*
294 * Unlock cookie management lock
295 */
296static inline void nfs_fscache_inode_unlock(struct inode *inode)
297{
298 struct nfs_inode *nfsi = NFS_I(inode);
299
300 smp_mb__before_clear_bit();
301 clear_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags);
302 smp_mb__after_clear_bit();
303 wake_up_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK);
304}
305
306/*
307 * Decide if we should enable or disable local caching for this inode.
308 * - For now, with NFS, only regular files that are open read-only will be able
309 * to use the cache.
310 * - May be invoked multiple times in parallel by parallel nfs_open() functions.
311 */
312void nfs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
313{
314 if (NFS_FSCACHE(inode)) {
315 nfs_fscache_inode_lock(inode);
316 if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
317 nfs_fscache_disable_inode_cookie(inode);
318 else
319 nfs_fscache_enable_inode_cookie(inode);
320 nfs_fscache_inode_unlock(inode);
321 }
322}
323
324/*
325 * Replace a per-inode cookie due to revalidation detecting a file having
326 * changed on the server.
327 */
328void nfs_fscache_reset_inode_cookie(struct inode *inode)
329{
330 struct nfs_inode *nfsi = NFS_I(inode);
331 struct nfs_server *nfss = NFS_SERVER(inode);
332 struct fscache_cookie *old = nfsi->fscache;
333
334 nfs_fscache_inode_lock(inode);
335 if (nfsi->fscache) {
336 /* retire the current fscache cache and get a new one */
337 fscache_relinquish_cookie(nfsi->fscache, 1);
338
339 nfsi->fscache = fscache_acquire_cookie(
340 nfss->nfs_client->fscache,
341 &nfs_fscache_inode_object_def,
342 nfsi);
343
344 dfprintk(FSCACHE,
345 "NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
346 nfss, nfsi, old, nfsi->fscache);
347 }
348 nfs_fscache_inode_unlock(inode);
349}
545db45f
DH
350
351/*
352 * Release the caching state associated with a page, if the page isn't busy
353 * interacting with the cache.
354 * - Returns true (can release page) or false (page busy).
355 */
356int nfs_fscache_release_page(struct page *page, gfp_t gfp)
357{
545db45f 358 if (PageFsCache(page)) {
2c174009
TM
359 struct nfs_inode *nfsi = NFS_I(page->mapping->host);
360 struct fscache_cookie *cookie = nfsi->fscache;
361
362 BUG_ON(!cookie);
545db45f
DH
363 dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
364 cookie, page, nfsi);
365
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DH
366 if (!fscache_maybe_release_page(cookie, page, gfp))
367 return 0;
368
545db45f
DH
369 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}
9a9fc1c0
DH
397
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{
0f15c53d
CL
470 unsigned npages = *nr_pages;
471 int ret;
9a9fc1c0
DH
472
473 dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
474 NFS_I(inode)->fscache, npages, inode);
475
476 ret = fscache_read_or_alloc_pages(NFS_I(inode)->fscache,
477 mapping, pages, nr_pages,
478 nfs_readpage_from_fscache_complete,
479 ctx,
480 mapping_gfp_mask(mapping));
481 if (*nr_pages < npages)
482 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
483 npages);
484 if (*nr_pages > 0)
485 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
486 *nr_pages);
487
488 switch (ret) {
489 case 0: /* read submitted to the cache for all pages */
490 BUG_ON(!list_empty(pages));
491 BUG_ON(*nr_pages != 0);
492 dfprintk(FSCACHE,
493 "NFS: nfs_getpages_from_fscache: submitted\n");
494
495 return ret;
496
497 case -ENOBUFS: /* some pages aren't cached and can't be */
498 case -ENODATA: /* some pages aren't cached */
499 dfprintk(FSCACHE,
500 "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
501 return 1;
502
503 default:
504 dfprintk(FSCACHE,
505 "NFS: nfs_getpages_from_fscache: ret %d\n", ret);
506 }
507
508 return ret;
509}
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DH
510
511/*
512 * Store a newly fetched page in fscache
513 * - PG_fscache must be set on the page
514 */
515void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
516{
517 int ret;
518
519 dfprintk(FSCACHE,
520 "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
521 NFS_I(inode)->fscache, page, page->index, page->flags, sync);
522
523 ret = fscache_write_page(NFS_I(inode)->fscache, page, GFP_KERNEL);
524 dfprintk(FSCACHE,
525 "NFS: readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
526 page, page->index, page->flags, ret);
527
528 if (ret != 0) {
529 fscache_uncache_page(NFS_I(inode)->fscache, page);
530 nfs_add_fscache_stats(inode,
531 NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1);
532 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
533 } else {
534 nfs_add_fscache_stats(inode,
535 NFSIOS_FSCACHE_PAGES_WRITTEN_OK, 1);
536 }
537}