xref: /openbmc/linux/fs/nfs/fscache.c (revision e8e0929d)
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  * 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.
65  */
66 void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq,
67 				  struct nfs_clone_mount *mntdata)
68 {
69 	struct nfs_fscache_key *key, *xkey;
70 	struct nfs_server *nfss = NFS_SB(sb);
71 	struct rb_node **p, *parent;
72 	int diff, ulen;
73 
74 	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 
89 	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 
157 non_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  */
169 void 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 }
187 
188 /*
189  * Initialise the per-inode cache cookie pointer for an NFS inode.
190  */
191 void 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  */
201 static 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  */
223 void 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  */
237 void 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  */
253 static 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  */
274 static 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  */
283 static 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  */
295 static 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  */
311 void 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  */
327 void 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 }
349 
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  */
355 int 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 
362 	if (fscache_check_page_write(cookie, page)) {
363 		if (!(gfp & __GFP_WAIT))
364 			return 0;
365 		fscache_wait_on_page_write(cookie, page);
366 	}
367 
368 	if (PageFsCache(page)) {
369 		dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
370 			 cookie, page, nfsi);
371 
372 		fscache_uncache_page(cookie, page);
373 		nfs_add_fscache_stats(page->mapping->host,
374 				      NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
375 	}
376 
377 	return 1;
378 }
379 
380 /*
381  * Release the caching state associated with a page if undergoing complete page
382  * invalidation.
383  */
384 void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
385 {
386 	struct nfs_inode *nfsi = NFS_I(inode);
387 	struct fscache_cookie *cookie = nfsi->fscache;
388 
389 	BUG_ON(!cookie);
390 
391 	dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
392 		 cookie, page, nfsi);
393 
394 	fscache_wait_on_page_write(cookie, page);
395 
396 	BUG_ON(!PageLocked(page));
397 	fscache_uncache_page(cookie, page);
398 	nfs_add_fscache_stats(page->mapping->host,
399 			      NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
400 }
401 
402 /*
403  * Handle completion of a page being read from the cache.
404  * - Called in process (keventd) context.
405  */
406 static void nfs_readpage_from_fscache_complete(struct page *page,
407 					       void *context,
408 					       int error)
409 {
410 	dfprintk(FSCACHE,
411 		 "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
412 		 page, context, error);
413 
414 	/* if the read completes with an error, we just unlock the page and let
415 	 * the VM reissue the readpage */
416 	if (!error) {
417 		SetPageUptodate(page);
418 		unlock_page(page);
419 	} else {
420 		error = nfs_readpage_async(context, page->mapping->host, page);
421 		if (error)
422 			unlock_page(page);
423 	}
424 }
425 
426 /*
427  * Retrieve a page from fscache
428  */
429 int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
430 				struct inode *inode, struct page *page)
431 {
432 	int ret;
433 
434 	dfprintk(FSCACHE,
435 		 "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
436 		 NFS_I(inode)->fscache, page, page->index, page->flags, inode);
437 
438 	ret = fscache_read_or_alloc_page(NFS_I(inode)->fscache,
439 					 page,
440 					 nfs_readpage_from_fscache_complete,
441 					 ctx,
442 					 GFP_KERNEL);
443 
444 	switch (ret) {
445 	case 0: /* read BIO submitted (page in fscache) */
446 		dfprintk(FSCACHE,
447 			 "NFS:    readpage_from_fscache: BIO submitted\n");
448 		nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK, 1);
449 		return ret;
450 
451 	case -ENOBUFS: /* inode not in cache */
452 	case -ENODATA: /* page not in cache */
453 		nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
454 		dfprintk(FSCACHE,
455 			 "NFS:    readpage_from_fscache %d\n", ret);
456 		return 1;
457 
458 	default:
459 		dfprintk(FSCACHE, "NFS:    readpage_from_fscache %d\n", ret);
460 		nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
461 	}
462 	return ret;
463 }
464 
465 /*
466  * Retrieve a set of pages from fscache
467  */
468 int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
469 				 struct inode *inode,
470 				 struct address_space *mapping,
471 				 struct list_head *pages,
472 				 unsigned *nr_pages)
473 {
474 	int ret, npages = *nr_pages;
475 
476 	dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
477 		 NFS_I(inode)->fscache, npages, inode);
478 
479 	ret = fscache_read_or_alloc_pages(NFS_I(inode)->fscache,
480 					  mapping, pages, nr_pages,
481 					  nfs_readpage_from_fscache_complete,
482 					  ctx,
483 					  mapping_gfp_mask(mapping));
484 	if (*nr_pages < npages)
485 		nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
486 				      npages);
487 	if (*nr_pages > 0)
488 		nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
489 				      *nr_pages);
490 
491 	switch (ret) {
492 	case 0: /* read submitted to the cache for all pages */
493 		BUG_ON(!list_empty(pages));
494 		BUG_ON(*nr_pages != 0);
495 		dfprintk(FSCACHE,
496 			 "NFS: nfs_getpages_from_fscache: submitted\n");
497 
498 		return ret;
499 
500 	case -ENOBUFS: /* some pages aren't cached and can't be */
501 	case -ENODATA: /* some pages aren't cached */
502 		dfprintk(FSCACHE,
503 			 "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
504 		return 1;
505 
506 	default:
507 		dfprintk(FSCACHE,
508 			 "NFS: nfs_getpages_from_fscache: ret  %d\n", ret);
509 	}
510 
511 	return ret;
512 }
513 
514 /*
515  * Store a newly fetched page in fscache
516  * - PG_fscache must be set on the page
517  */
518 void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
519 {
520 	int ret;
521 
522 	dfprintk(FSCACHE,
523 		 "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
524 		 NFS_I(inode)->fscache, page, page->index, page->flags, sync);
525 
526 	ret = fscache_write_page(NFS_I(inode)->fscache, page, GFP_KERNEL);
527 	dfprintk(FSCACHE,
528 		 "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
529 		 page, page->index, page->flags, ret);
530 
531 	if (ret != 0) {
532 		fscache_uncache_page(NFS_I(inode)->fscache, page);
533 		nfs_add_fscache_stats(inode,
534 				      NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1);
535 		nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
536 	} else {
537 		nfs_add_fscache_stats(inode,
538 				      NFSIOS_FSCACHE_PAGES_WRITTEN_OK, 1);
539 	}
540 }
541