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1// SPDX-License-Identifier: GPL-2.0
2
3/*
4 * Copyright 2019, 2020 Amazon.com, Inc. or its affiliates. All rights reserved.
5 *
6 * User extended attribute client side cache functions.
7 *
8 * Author: Frank van der Linden <fllinden@amazon.com>
9 */
10#include <linux/errno.h>
11#include <linux/nfs_fs.h>
12#include <linux/hashtable.h>
13#include <linux/refcount.h>
14#include <uapi/linux/xattr.h>
15
16#include "nfs4_fs.h"
17#include "internal.h"
18
19/*
20 * User extended attributes client side caching is implemented by having
21 * a cache structure attached to NFS inodes. This structure is allocated
22 * when needed, and freed when the cache is zapped.
23 *
24 * The cache structure contains as hash table of entries, and a pointer
25 * to a special-cased entry for the listxattr cache.
26 *
27 * Accessing and allocating / freeing the caches is done via reference
28 * counting. The cache entries use a similar refcounting scheme.
29 *
30 * This makes freeing a cache, both from the shrinker and from the
31 * zap cache path, easy. It also means that, in current use cases,
32 * the large majority of inodes will not waste any memory, as they
33 * will never have any user extended attributes assigned to them.
34 *
35 * Attribute entries are hashed in to a simple hash table. They are
36 * also part of an LRU.
37 *
38 * There are three shrinkers.
39 *
40 * Two shrinkers deal with the cache entries themselves: one for
41 * large entries (> PAGE_SIZE), and one for smaller entries. The
42 * shrinker for the larger entries works more aggressively than
43 * those for the smaller entries.
44 *
45 * The other shrinker frees the cache structures themselves.
46 */
47
48/*
49 * 64 buckets is a good default. There is likely no reasonable
50 * workload that uses more than even 64 user extended attributes.
51 * You can certainly add a lot more - but you get what you ask for
52 * in those circumstances.
53 */
54#define NFS4_XATTR_HASH_SIZE 64
55
56#define NFSDBG_FACILITY NFSDBG_XATTRCACHE
57
58struct nfs4_xattr_cache;
59struct nfs4_xattr_entry;
60
61struct nfs4_xattr_bucket {
62 spinlock_t lock;
63 struct hlist_head hlist;
64 struct nfs4_xattr_cache *cache;
65 bool draining;
66};
67
68struct nfs4_xattr_cache {
69 struct kref ref;
70 struct nfs4_xattr_bucket buckets[NFS4_XATTR_HASH_SIZE];
71 struct list_head lru;
72 struct list_head dispose;
73 atomic_long_t nent;
74 spinlock_t listxattr_lock;
75 struct inode *inode;
76 struct nfs4_xattr_entry *listxattr;
77};
78
79struct nfs4_xattr_entry {
80 struct kref ref;
81 struct hlist_node hnode;
82 struct list_head lru;
83 struct list_head dispose;
84 char *xattr_name;
85 void *xattr_value;
86 size_t xattr_size;
87 struct nfs4_xattr_bucket *bucket;
88 uint32_t flags;
89};
90
91#define NFS4_XATTR_ENTRY_EXTVAL 0x0001
92
93/*
94 * LRU list of NFS inodes that have xattr caches.
95 */
96static struct list_lru nfs4_xattr_cache_lru;
97static struct list_lru nfs4_xattr_entry_lru;
98static struct list_lru nfs4_xattr_large_entry_lru;
99
100static struct kmem_cache *nfs4_xattr_cache_cachep;
101
102/*
103 * Hashing helper functions.
104 */
105static void
106nfs4_xattr_hash_init(struct nfs4_xattr_cache *cache)
107{
108 unsigned int i;
109
110 for (i = 0; i < NFS4_XATTR_HASH_SIZE; i++) {
111 INIT_HLIST_HEAD(&cache->buckets[i].hlist);
112 spin_lock_init(&cache->buckets[i].lock);
113 cache->buckets[i].cache = cache;
114 cache->buckets[i].draining = false;
115 }
116}
117
118/*
119 * Locking order:
120 * 1. inode i_lock or bucket lock
121 * 2. list_lru lock (taken by list_lru_* functions)
122 */
123
124/*
125 * Wrapper functions to add a cache entry to the right LRU.
126 */
127static bool
128nfs4_xattr_entry_lru_add(struct nfs4_xattr_entry *entry)
129{
130 struct list_lru *lru;
131
132 lru = (entry->flags & NFS4_XATTR_ENTRY_EXTVAL) ?
133 &nfs4_xattr_large_entry_lru : &nfs4_xattr_entry_lru;
134
135 return list_lru_add(lru, &entry->lru);
136}
137
138static bool
139nfs4_xattr_entry_lru_del(struct nfs4_xattr_entry *entry)
140{
141 struct list_lru *lru;
142
143 lru = (entry->flags & NFS4_XATTR_ENTRY_EXTVAL) ?
144 &nfs4_xattr_large_entry_lru : &nfs4_xattr_entry_lru;
145
146 return list_lru_del(lru, &entry->lru);
147}
148
149/*
150 * This function allocates cache entries. They are the normal
151 * extended attribute name/value pairs, but may also be a listxattr
152 * cache. Those allocations use the same entry so that they can be
153 * treated as one by the memory shrinker.
154 *
155 * xattr cache entries are allocated together with names. If the
156 * value fits in to one page with the entry structure and the name,
157 * it will also be part of the same allocation (kmalloc). This is
158 * expected to be the vast majority of cases. Larger allocations
159 * have a value pointer that is allocated separately by kvmalloc.
160 *
161 * Parameters:
162 *
163 * @name: Name of the extended attribute. NULL for listxattr cache
164 * entry.
165 * @value: Value of attribute, or listxattr cache. NULL if the
166 * value is to be copied from pages instead.
167 * @pages: Pages to copy the value from, if not NULL. Passed in to
168 * make it easier to copy the value after an RPC, even if
169 * the value will not be passed up to application (e.g.
170 * for a 'query' getxattr with NULL buffer).
171 * @len: Length of the value. Can be 0 for zero-length attributes.
172 * @value and @pages will be NULL if @len is 0.
173 */
174static struct nfs4_xattr_entry *
175nfs4_xattr_alloc_entry(const char *name, const void *value,
176 struct page **pages, size_t len)
177{
178 struct nfs4_xattr_entry *entry;
179 void *valp;
180 char *namep;
181 size_t alloclen, slen;
182 char *buf;
183 uint32_t flags;
184
185 BUILD_BUG_ON(sizeof(struct nfs4_xattr_entry) +
186 XATTR_NAME_MAX + 1 > PAGE_SIZE);
187
188 alloclen = sizeof(struct nfs4_xattr_entry);
189 if (name != NULL) {
190 slen = strlen(name) + 1;
191 alloclen += slen;
192 } else
193 slen = 0;
194
195 if (alloclen + len <= PAGE_SIZE) {
196 alloclen += len;
197 flags = 0;
198 } else {
199 flags = NFS4_XATTR_ENTRY_EXTVAL;
200 }
201
202 buf = kmalloc(alloclen, GFP_KERNEL);
203 if (buf == NULL)
204 return NULL;
205 entry = (struct nfs4_xattr_entry *)buf;
206
207 if (name != NULL) {
208 namep = buf + sizeof(struct nfs4_xattr_entry);
209 memcpy(namep, name, slen);
210 } else {
211 namep = NULL;
212 }
213
214
215 if (flags & NFS4_XATTR_ENTRY_EXTVAL) {
216 valp = kvmalloc(len, GFP_KERNEL);
217 if (valp == NULL) {
218 kfree(buf);
219 return NULL;
220 }
221 } else if (len != 0) {
222 valp = buf + sizeof(struct nfs4_xattr_entry) + slen;
223 } else
224 valp = NULL;
225
226 if (valp != NULL) {
227 if (value != NULL)
228 memcpy(valp, value, len);
229 else
230 _copy_from_pages(valp, pages, 0, len);
231 }
232
233 entry->flags = flags;
234 entry->xattr_value = valp;
235 kref_init(&entry->ref);
236 entry->xattr_name = namep;
237 entry->xattr_size = len;
238 entry->bucket = NULL;
239 INIT_LIST_HEAD(&entry->lru);
240 INIT_LIST_HEAD(&entry->dispose);
241 INIT_HLIST_NODE(&entry->hnode);
242
243 return entry;
244}
245
246static void
247nfs4_xattr_free_entry(struct nfs4_xattr_entry *entry)
248{
249 if (entry->flags & NFS4_XATTR_ENTRY_EXTVAL)
250 kvfree(entry->xattr_value);
251 kfree(entry);
252}
253
254static void
255nfs4_xattr_free_entry_cb(struct kref *kref)
256{
257 struct nfs4_xattr_entry *entry;
258
259 entry = container_of(kref, struct nfs4_xattr_entry, ref);
260
261 if (WARN_ON(!list_empty(&entry->lru)))
262 return;
263
264 nfs4_xattr_free_entry(entry);
265}
266
267static void
268nfs4_xattr_free_cache_cb(struct kref *kref)
269{
270 struct nfs4_xattr_cache *cache;
271 int i;
272
273 cache = container_of(kref, struct nfs4_xattr_cache, ref);
274
275 for (i = 0; i < NFS4_XATTR_HASH_SIZE; i++) {
276 if (WARN_ON(!hlist_empty(&cache->buckets[i].hlist)))
277 return;
278 cache->buckets[i].draining = false;
279 }
280
281 cache->listxattr = NULL;
282
283 kmem_cache_free(nfs4_xattr_cache_cachep, cache);
284
285}
286
287static struct nfs4_xattr_cache *
288nfs4_xattr_alloc_cache(void)
289{
290 struct nfs4_xattr_cache *cache;
291
292 cache = kmem_cache_alloc(nfs4_xattr_cache_cachep, GFP_KERNEL);
293 if (cache == NULL)
294 return NULL;
295
296 kref_init(&cache->ref);
297 atomic_long_set(&cache->nent, 0);
298
299 return cache;
300}
301
302/*
303 * Set the listxattr cache, which is a special-cased cache entry.
304 * The special value ERR_PTR(-ESTALE) is used to indicate that
305 * the cache is being drained - this prevents a new listxattr
306 * cache from being added to what is now a stale cache.
307 */
308static int
309nfs4_xattr_set_listcache(struct nfs4_xattr_cache *cache,
310 struct nfs4_xattr_entry *new)
311{
312 struct nfs4_xattr_entry *old;
313 int ret = 1;
314
315 spin_lock(&cache->listxattr_lock);
316
317 old = cache->listxattr;
318
319 if (old == ERR_PTR(-ESTALE)) {
320 ret = 0;
321 goto out;
322 }
323
324 cache->listxattr = new;
325 if (new != NULL && new != ERR_PTR(-ESTALE))
326 nfs4_xattr_entry_lru_add(new);
327
328 if (old != NULL) {
329 nfs4_xattr_entry_lru_del(old);
330 kref_put(&old->ref, nfs4_xattr_free_entry_cb);
331 }
332out:
333 spin_unlock(&cache->listxattr_lock);
334
335 return ret;
336}
337
338/*
339 * Unlink a cache from its parent inode, clearing out an invalid
340 * cache. Must be called with i_lock held.
341 */
342static struct nfs4_xattr_cache *
343nfs4_xattr_cache_unlink(struct inode *inode)
344{
345 struct nfs_inode *nfsi;
346 struct nfs4_xattr_cache *oldcache;
347
348 nfsi = NFS_I(inode);
349
350 oldcache = nfsi->xattr_cache;
351 if (oldcache != NULL) {
352 list_lru_del(&nfs4_xattr_cache_lru, &oldcache->lru);
353 oldcache->inode = NULL;
354 }
355 nfsi->xattr_cache = NULL;
356 nfsi->cache_validity &= ~NFS_INO_INVALID_XATTR;
357
358 return oldcache;
359
360}
361
362/*
363 * Discard a cache. Called by get_cache() if there was an old,
364 * invalid cache. Can also be called from a shrinker callback.
365 *
366 * The cache is dead, it has already been unlinked from its inode,
367 * and no longer appears on the cache LRU list.
368 *
369 * Mark all buckets as draining, so that no new entries are added. This
370 * could still happen in the unlikely, but possible case that another
371 * thread had grabbed a reference before it was unlinked from the inode,
372 * and is still holding it for an add operation.
373 *
374 * Remove all entries from the LRU lists, so that there is no longer
375 * any way to 'find' this cache. Then, remove the entries from the hash
376 * table.
377 *
378 * At that point, the cache will remain empty and can be freed when the final
379 * reference drops, which is very likely the kref_put at the end of
380 * this function, or the one called immediately afterwards in the
381 * shrinker callback.
382 */
383static void
384nfs4_xattr_discard_cache(struct nfs4_xattr_cache *cache)
385{
386 unsigned int i;
387 struct nfs4_xattr_entry *entry;
388 struct nfs4_xattr_bucket *bucket;
389 struct hlist_node *n;
390
391 nfs4_xattr_set_listcache(cache, ERR_PTR(-ESTALE));
392
393 for (i = 0; i < NFS4_XATTR_HASH_SIZE; i++) {
394 bucket = &cache->buckets[i];
395
396 spin_lock(&bucket->lock);
397 bucket->draining = true;
398 hlist_for_each_entry_safe(entry, n, &bucket->hlist, hnode) {
399 nfs4_xattr_entry_lru_del(entry);
400 hlist_del_init(&entry->hnode);
401 kref_put(&entry->ref, nfs4_xattr_free_entry_cb);
402 }
403 spin_unlock(&bucket->lock);
404 }
405
406 atomic_long_set(&cache->nent, 0);
407
408 kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
409}
410
411/*
412 * Get a referenced copy of the cache structure. Avoid doing allocs
413 * while holding i_lock. Which means that we do some optimistic allocation,
414 * and might have to free the result in rare cases.
415 *
416 * This function only checks the NFS_INO_INVALID_XATTR cache validity bit
417 * and acts accordingly, replacing the cache when needed. For the read case
418 * (!add), this means that the caller must make sure that the cache
419 * is valid before caling this function. getxattr and listxattr call
420 * revalidate_inode to do this. The attribute cache timeout (for the
421 * non-delegated case) is expected to be dealt with in the revalidate
422 * call.
423 */
424
425static struct nfs4_xattr_cache *
426nfs4_xattr_get_cache(struct inode *inode, int add)
427{
428 struct nfs_inode *nfsi;
429 struct nfs4_xattr_cache *cache, *oldcache, *newcache;
430
431 nfsi = NFS_I(inode);
432
433 cache = oldcache = NULL;
434
435 spin_lock(&inode->i_lock);
436
437 if (nfsi->cache_validity & NFS_INO_INVALID_XATTR)
438 oldcache = nfs4_xattr_cache_unlink(inode);
439 else
440 cache = nfsi->xattr_cache;
441
442 if (cache != NULL)
443 kref_get(&cache->ref);
444
445 spin_unlock(&inode->i_lock);
446
447 if (add && cache == NULL) {
448 newcache = NULL;
449
450 cache = nfs4_xattr_alloc_cache();
451 if (cache == NULL)
452 goto out;
453
454 spin_lock(&inode->i_lock);
455 if (nfsi->cache_validity & NFS_INO_INVALID_XATTR) {
456 /*
457 * The cache was invalidated again. Give up,
458 * since what we want to enter is now likely
459 * outdated anyway.
460 */
461 spin_unlock(&inode->i_lock);
462 kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
463 cache = NULL;
464 goto out;
465 }
466
467 /*
468 * Check if someone beat us to it.
469 */
470 if (nfsi->xattr_cache != NULL) {
471 newcache = nfsi->xattr_cache;
472 kref_get(&newcache->ref);
473 } else {
474 kref_get(&cache->ref);
475 nfsi->xattr_cache = cache;
476 cache->inode = inode;
477 list_lru_add(&nfs4_xattr_cache_lru, &cache->lru);
478 }
479
480 spin_unlock(&inode->i_lock);
481
482 /*
483 * If there was a race, throw away the cache we just
484 * allocated, and use the new one allocated by someone
485 * else.
486 */
487 if (newcache != NULL) {
488 kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
489 cache = newcache;
490 }
491 }
492
493out:
494 /*
495 * Discard the now orphaned old cache.
496 */
497 if (oldcache != NULL)
498 nfs4_xattr_discard_cache(oldcache);
499
500 return cache;
501}
502
503static inline struct nfs4_xattr_bucket *
504nfs4_xattr_hash_bucket(struct nfs4_xattr_cache *cache, const char *name)
505{
506 return &cache->buckets[jhash(name, strlen(name), 0) &
507 (ARRAY_SIZE(cache->buckets) - 1)];
508}
509
510static struct nfs4_xattr_entry *
511nfs4_xattr_get_entry(struct nfs4_xattr_bucket *bucket, const char *name)
512{
513 struct nfs4_xattr_entry *entry;
514
515 entry = NULL;
516
517 hlist_for_each_entry(entry, &bucket->hlist, hnode) {
518 if (!strcmp(entry->xattr_name, name))
519 break;
520 }
521
522 return entry;
523}
524
525static int
526nfs4_xattr_hash_add(struct nfs4_xattr_cache *cache,
527 struct nfs4_xattr_entry *entry)
528{
529 struct nfs4_xattr_bucket *bucket;
530 struct nfs4_xattr_entry *oldentry = NULL;
531 int ret = 1;
532
533 bucket = nfs4_xattr_hash_bucket(cache, entry->xattr_name);
534 entry->bucket = bucket;
535
536 spin_lock(&bucket->lock);
537
538 if (bucket->draining) {
539 ret = 0;
540 goto out;
541 }
542
543 oldentry = nfs4_xattr_get_entry(bucket, entry->xattr_name);
544 if (oldentry != NULL) {
545 hlist_del_init(&oldentry->hnode);
546 nfs4_xattr_entry_lru_del(oldentry);
547 } else {
548 atomic_long_inc(&cache->nent);
549 }
550
551 hlist_add_head(&entry->hnode, &bucket->hlist);
552 nfs4_xattr_entry_lru_add(entry);
553
554out:
555 spin_unlock(&bucket->lock);
556
557 if (oldentry != NULL)
558 kref_put(&oldentry->ref, nfs4_xattr_free_entry_cb);
559
560 return ret;
561}
562
563static void
564nfs4_xattr_hash_remove(struct nfs4_xattr_cache *cache, const char *name)
565{
566 struct nfs4_xattr_bucket *bucket;
567 struct nfs4_xattr_entry *entry;
568
569 bucket = nfs4_xattr_hash_bucket(cache, name);
570
571 spin_lock(&bucket->lock);
572
573 entry = nfs4_xattr_get_entry(bucket, name);
574 if (entry != NULL) {
575 hlist_del_init(&entry->hnode);
576 nfs4_xattr_entry_lru_del(entry);
577 atomic_long_dec(&cache->nent);
578 }
579
580 spin_unlock(&bucket->lock);
581
582 if (entry != NULL)
583 kref_put(&entry->ref, nfs4_xattr_free_entry_cb);
584}
585
586static struct nfs4_xattr_entry *
587nfs4_xattr_hash_find(struct nfs4_xattr_cache *cache, const char *name)
588{
589 struct nfs4_xattr_bucket *bucket;
590 struct nfs4_xattr_entry *entry;
591
592 bucket = nfs4_xattr_hash_bucket(cache, name);
593
594 spin_lock(&bucket->lock);
595
596 entry = nfs4_xattr_get_entry(bucket, name);
597 if (entry != NULL)
598 kref_get(&entry->ref);
599
600 spin_unlock(&bucket->lock);
601
602 return entry;
603}
604
605/*
606 * Entry point to retrieve an entry from the cache.
607 */
608ssize_t nfs4_xattr_cache_get(struct inode *inode, const char *name, char *buf,
609 ssize_t buflen)
610{
611 struct nfs4_xattr_cache *cache;
612 struct nfs4_xattr_entry *entry;
613 ssize_t ret;
614
615 cache = nfs4_xattr_get_cache(inode, 0);
616 if (cache == NULL)
617 return -ENOENT;
618
619 ret = 0;
620 entry = nfs4_xattr_hash_find(cache, name);
621
622 if (entry != NULL) {
623 dprintk("%s: cache hit '%s', len %lu\n", __func__,
624 entry->xattr_name, (unsigned long)entry->xattr_size);
625 if (buflen == 0) {
626 /* Length probe only */
627 ret = entry->xattr_size;
628 } else if (buflen < entry->xattr_size)
629 ret = -ERANGE;
630 else {
631 memcpy(buf, entry->xattr_value, entry->xattr_size);
632 ret = entry->xattr_size;
633 }
634 kref_put(&entry->ref, nfs4_xattr_free_entry_cb);
635 } else {
636 dprintk("%s: cache miss '%s'\n", __func__, name);
637 ret = -ENOENT;
638 }
639
640 kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
641
642 return ret;
643}
644
645/*
646 * Retrieve a cached list of xattrs from the cache.
647 */
648ssize_t nfs4_xattr_cache_list(struct inode *inode, char *buf, ssize_t buflen)
649{
650 struct nfs4_xattr_cache *cache;
651 struct nfs4_xattr_entry *entry;
652 ssize_t ret;
653
654 cache = nfs4_xattr_get_cache(inode, 0);
655 if (cache == NULL)
656 return -ENOENT;
657
658 spin_lock(&cache->listxattr_lock);
659
660 entry = cache->listxattr;
661
662 if (entry != NULL && entry != ERR_PTR(-ESTALE)) {
663 if (buflen == 0) {
664 /* Length probe only */
665 ret = entry->xattr_size;
666 } else if (entry->xattr_size > buflen)
667 ret = -ERANGE;
668 else {
669 memcpy(buf, entry->xattr_value, entry->xattr_size);
670 ret = entry->xattr_size;
671 }
672 } else {
673 ret = -ENOENT;
674 }
675
676 spin_unlock(&cache->listxattr_lock);
677
678 kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
679
680 return ret;
681}
682
683/*
684 * Add an xattr to the cache.
685 *
686 * This also invalidates the xattr list cache.
687 */
688void nfs4_xattr_cache_add(struct inode *inode, const char *name,
689 const char *buf, struct page **pages, ssize_t buflen)
690{
691 struct nfs4_xattr_cache *cache;
692 struct nfs4_xattr_entry *entry;
693
694 dprintk("%s: add '%s' len %lu\n", __func__,
695 name, (unsigned long)buflen);
696
697 cache = nfs4_xattr_get_cache(inode, 1);
698 if (cache == NULL)
699 return;
700
701 entry = nfs4_xattr_alloc_entry(name, buf, pages, buflen);
702 if (entry == NULL)
703 goto out;
704
705 (void)nfs4_xattr_set_listcache(cache, NULL);
706
707 if (!nfs4_xattr_hash_add(cache, entry))
708 kref_put(&entry->ref, nfs4_xattr_free_entry_cb);
709
710out:
711 kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
712}
713
714
715/*
716 * Remove an xattr from the cache.
717 *
718 * This also invalidates the xattr list cache.
719 */
720void nfs4_xattr_cache_remove(struct inode *inode, const char *name)
721{
722 struct nfs4_xattr_cache *cache;
723
724 dprintk("%s: remove '%s'\n", __func__, name);
725
726 cache = nfs4_xattr_get_cache(inode, 0);
727 if (cache == NULL)
728 return;
729
730 (void)nfs4_xattr_set_listcache(cache, NULL);
731 nfs4_xattr_hash_remove(cache, name);
732
733 kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
734}
735
736/*
737 * Cache listxattr output, replacing any possible old one.
738 */
739void nfs4_xattr_cache_set_list(struct inode *inode, const char *buf,
740 ssize_t buflen)
741{
742 struct nfs4_xattr_cache *cache;
743 struct nfs4_xattr_entry *entry;
744
745 cache = nfs4_xattr_get_cache(inode, 1);
746 if (cache == NULL)
747 return;
748
749 entry = nfs4_xattr_alloc_entry(NULL, buf, NULL, buflen);
750 if (entry == NULL)
751 goto out;
752
753 /*
754 * This is just there to be able to get to bucket->cache,
755 * which is obviously the same for all buckets, so just
756 * use bucket 0.
757 */
758 entry->bucket = &cache->buckets[0];
759
760 if (!nfs4_xattr_set_listcache(cache, entry))
761 kref_put(&entry->ref, nfs4_xattr_free_entry_cb);
762
763out:
764 kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
765}
766
767/*
768 * Zap the entire cache. Called when an inode is evicted.
769 */
770void nfs4_xattr_cache_zap(struct inode *inode)
771{
772 struct nfs4_xattr_cache *oldcache;
773
774 spin_lock(&inode->i_lock);
775 oldcache = nfs4_xattr_cache_unlink(inode);
776 spin_unlock(&inode->i_lock);
777
778 if (oldcache)
779 nfs4_xattr_discard_cache(oldcache);
780}
781
782/*
783 * The entry LRU is shrunk more aggressively than the cache LRU,
784 * by settings @seeks to 1.
785 *
786 * Cache structures are freed only when they've become empty, after
787 * pruning all but one entry.
788 */
789
790static unsigned long nfs4_xattr_cache_count(struct shrinker *shrink,
791 struct shrink_control *sc);
792static unsigned long nfs4_xattr_entry_count(struct shrinker *shrink,
793 struct shrink_control *sc);
794static unsigned long nfs4_xattr_cache_scan(struct shrinker *shrink,
795 struct shrink_control *sc);
796static unsigned long nfs4_xattr_entry_scan(struct shrinker *shrink,
797 struct shrink_control *sc);
798
799static struct shrinker nfs4_xattr_cache_shrinker = {
800 .count_objects = nfs4_xattr_cache_count,
801 .scan_objects = nfs4_xattr_cache_scan,
802 .seeks = DEFAULT_SEEKS,
803 .flags = SHRINKER_MEMCG_AWARE,
804};
805
806static struct shrinker nfs4_xattr_entry_shrinker = {
807 .count_objects = nfs4_xattr_entry_count,
808 .scan_objects = nfs4_xattr_entry_scan,
809 .seeks = DEFAULT_SEEKS,
810 .batch = 512,
811 .flags = SHRINKER_MEMCG_AWARE,
812};
813
814static struct shrinker nfs4_xattr_large_entry_shrinker = {
815 .count_objects = nfs4_xattr_entry_count,
816 .scan_objects = nfs4_xattr_entry_scan,
817 .seeks = 1,
818 .batch = 512,
819 .flags = SHRINKER_MEMCG_AWARE,
820};
821
822static enum lru_status
823cache_lru_isolate(struct list_head *item,
824 struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
825{
826 struct list_head *dispose = arg;
827 struct inode *inode;
828 struct nfs4_xattr_cache *cache = container_of(item,
829 struct nfs4_xattr_cache, lru);
830
831 if (atomic_long_read(&cache->nent) > 1)
832 return LRU_SKIP;
833
834 /*
835 * If a cache structure is on the LRU list, we know that
836 * its inode is valid. Try to lock it to break the link.
837 * Since we're inverting the lock order here, only try.
838 */
839 inode = cache->inode;
840
841 if (!spin_trylock(&inode->i_lock))
842 return LRU_SKIP;
843
844 kref_get(&cache->ref);
845
846 cache->inode = NULL;
847 NFS_I(inode)->xattr_cache = NULL;
848 NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_XATTR;
849 list_lru_isolate(lru, &cache->lru);
850
851 spin_unlock(&inode->i_lock);
852
853 list_add_tail(&cache->dispose, dispose);
854 return LRU_REMOVED;
855}
856
857static unsigned long
858nfs4_xattr_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
859{
860 LIST_HEAD(dispose);
861 unsigned long freed;
862 struct nfs4_xattr_cache *cache;
863
864 freed = list_lru_shrink_walk(&nfs4_xattr_cache_lru, sc,
865 cache_lru_isolate, &dispose);
866 while (!list_empty(&dispose)) {
867 cache = list_first_entry(&dispose, struct nfs4_xattr_cache,
868 dispose);
869 list_del_init(&cache->dispose);
870 nfs4_xattr_discard_cache(cache);
871 kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
872 }
873
874 return freed;
875}
876
877
878static unsigned long
879nfs4_xattr_cache_count(struct shrinker *shrink, struct shrink_control *sc)
880{
881 unsigned long count;
882
883 count = list_lru_shrink_count(&nfs4_xattr_cache_lru, sc);
884 return vfs_pressure_ratio(count);
885}
886
887static enum lru_status
888entry_lru_isolate(struct list_head *item,
889 struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
890{
891 struct list_head *dispose = arg;
892 struct nfs4_xattr_bucket *bucket;
893 struct nfs4_xattr_cache *cache;
894 struct nfs4_xattr_entry *entry = container_of(item,
895 struct nfs4_xattr_entry, lru);
896
897 bucket = entry->bucket;
898 cache = bucket->cache;
899
900 /*
901 * Unhook the entry from its parent (either a cache bucket
902 * or a cache structure if it's a listxattr buf), so that
903 * it's no longer found. Then add it to the isolate list,
904 * to be freed later.
905 *
906 * In both cases, we're reverting lock order, so use
907 * trylock and skip the entry if we can't get the lock.
908 */
909 if (entry->xattr_name != NULL) {
910 /* Regular cache entry */
911 if (!spin_trylock(&bucket->lock))
912 return LRU_SKIP;
913
914 kref_get(&entry->ref);
915
916 hlist_del_init(&entry->hnode);
917 atomic_long_dec(&cache->nent);
918 list_lru_isolate(lru, &entry->lru);
919
920 spin_unlock(&bucket->lock);
921 } else {
922 /* Listxattr cache entry */
923 if (!spin_trylock(&cache->listxattr_lock))
924 return LRU_SKIP;
925
926 kref_get(&entry->ref);
927
928 cache->listxattr = NULL;
929 list_lru_isolate(lru, &entry->lru);
930
931 spin_unlock(&cache->listxattr_lock);
932 }
933
934 list_add_tail(&entry->dispose, dispose);
935 return LRU_REMOVED;
936}
937
938static unsigned long
939nfs4_xattr_entry_scan(struct shrinker *shrink, struct shrink_control *sc)
940{
941 LIST_HEAD(dispose);
942 unsigned long freed;
943 struct nfs4_xattr_entry *entry;
944 struct list_lru *lru;
945
946 lru = (shrink == &nfs4_xattr_large_entry_shrinker) ?
947 &nfs4_xattr_large_entry_lru : &nfs4_xattr_entry_lru;
948
949 freed = list_lru_shrink_walk(lru, sc, entry_lru_isolate, &dispose);
950
951 while (!list_empty(&dispose)) {
952 entry = list_first_entry(&dispose, struct nfs4_xattr_entry,
953 dispose);
954 list_del_init(&entry->dispose);
955
956 /*
957 * Drop two references: the one that we just grabbed
958 * in entry_lru_isolate, and the one that was set
959 * when the entry was first allocated.
960 */
961 kref_put(&entry->ref, nfs4_xattr_free_entry_cb);
962 kref_put(&entry->ref, nfs4_xattr_free_entry_cb);
963 }
964
965 return freed;
966}
967
968static unsigned long
969nfs4_xattr_entry_count(struct shrinker *shrink, struct shrink_control *sc)
970{
971 unsigned long count;
972 struct list_lru *lru;
973
974 lru = (shrink == &nfs4_xattr_large_entry_shrinker) ?
975 &nfs4_xattr_large_entry_lru : &nfs4_xattr_entry_lru;
976
977 count = list_lru_shrink_count(lru, sc);
978 return vfs_pressure_ratio(count);
979}
980
981
982static void nfs4_xattr_cache_init_once(void *p)
983{
984 struct nfs4_xattr_cache *cache = p;
985
986 spin_lock_init(&cache->listxattr_lock);
987 atomic_long_set(&cache->nent, 0);
988 nfs4_xattr_hash_init(cache);
989 cache->listxattr = NULL;
990 INIT_LIST_HEAD(&cache->lru);
991 INIT_LIST_HEAD(&cache->dispose);
992}
993
994int __init nfs4_xattr_cache_init(void)
995{
996 int ret = 0;
997
998 nfs4_xattr_cache_cachep = kmem_cache_create("nfs4_xattr_cache_cache",
999 sizeof(struct nfs4_xattr_cache), 0,
1000 (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD),
1001 nfs4_xattr_cache_init_once);
1002 if (nfs4_xattr_cache_cachep == NULL)
1003 return -ENOMEM;
1004
1005 ret = list_lru_init_memcg(&nfs4_xattr_large_entry_lru,
1006 &nfs4_xattr_large_entry_shrinker);
1007 if (ret)
1008 goto out4;
1009
1010 ret = list_lru_init_memcg(&nfs4_xattr_entry_lru,
1011 &nfs4_xattr_entry_shrinker);
1012 if (ret)
1013 goto out3;
1014
1015 ret = list_lru_init_memcg(&nfs4_xattr_cache_lru,
1016 &nfs4_xattr_cache_shrinker);
1017 if (ret)
1018 goto out2;
1019
1020 ret = register_shrinker(&nfs4_xattr_cache_shrinker, "nfs-xattr_cache");
1021 if (ret)
1022 goto out1;
1023
1024 ret = register_shrinker(&nfs4_xattr_entry_shrinker, "nfs-xattr_entry");
1025 if (ret)
1026 goto out;
1027
1028 ret = register_shrinker(&nfs4_xattr_large_entry_shrinker,
1029 "nfs-xattr_large_entry");
1030 if (!ret)
1031 return 0;
1032
1033 unregister_shrinker(&nfs4_xattr_entry_shrinker);
1034out:
1035 unregister_shrinker(&nfs4_xattr_cache_shrinker);
1036out1:
1037 list_lru_destroy(&nfs4_xattr_cache_lru);
1038out2:
1039 list_lru_destroy(&nfs4_xattr_entry_lru);
1040out3:
1041 list_lru_destroy(&nfs4_xattr_large_entry_lru);
1042out4:
1043 kmem_cache_destroy(nfs4_xattr_cache_cachep);
1044
1045 return ret;
1046}
1047
1048void nfs4_xattr_cache_exit(void)
1049{
1050 unregister_shrinker(&nfs4_xattr_large_entry_shrinker);
1051 unregister_shrinker(&nfs4_xattr_entry_shrinker);
1052 unregister_shrinker(&nfs4_xattr_cache_shrinker);
1053 list_lru_destroy(&nfs4_xattr_large_entry_lru);
1054 list_lru_destroy(&nfs4_xattr_entry_lru);
1055 list_lru_destroy(&nfs4_xattr_cache_lru);
1056 kmem_cache_destroy(nfs4_xattr_cache_cachep);
1057}