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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * The NFSD open file cache.
4 *
5 * (c) 2015 - Jeff Layton <jeff.layton@primarydata.com>
6 *
7 * An nfsd_file object is a per-file collection of open state that binds
8 * together:
9 * - a struct file *
10 * - a user credential
11 * - a network namespace
12 * - a read-ahead context
13 * - monitoring for writeback errors
14 *
15 * nfsd_file objects are reference-counted. Consumers acquire a new
16 * object via the nfsd_file_acquire API. They manage their interest in
17 * the acquired object, and hence the object's reference count, via
18 * nfsd_file_get and nfsd_file_put. There are two varieties of nfsd_file
19 * object:
20 *
21 * * non-garbage-collected: When a consumer wants to precisely control
22 * the lifetime of a file's open state, it acquires a non-garbage-
23 * collected nfsd_file. The final nfsd_file_put releases the open
24 * state immediately.
25 *
26 * * garbage-collected: When a consumer does not control the lifetime
27 * of open state, it acquires a garbage-collected nfsd_file. The
28 * final nfsd_file_put allows the open state to linger for a period
29 * during which it may be re-used.
30 */
31
32#include <linux/hash.h>
33#include <linux/slab.h>
34#include <linux/file.h>
35#include <linux/pagemap.h>
36#include <linux/sched.h>
37#include <linux/list_lru.h>
38#include <linux/fsnotify_backend.h>
39#include <linux/fsnotify.h>
40#include <linux/seq_file.h>
41#include <linux/rhashtable.h>
42
43#include "vfs.h"
44#include "nfsd.h"
45#include "nfsfh.h"
46#include "netns.h"
47#include "filecache.h"
48#include "trace.h"
49
50#define NFSD_LAUNDRETTE_DELAY (2 * HZ)
51
52#define NFSD_FILE_CACHE_UP (0)
53
54/* We only care about NFSD_MAY_READ/WRITE for this cache */
55#define NFSD_FILE_MAY_MASK (NFSD_MAY_READ|NFSD_MAY_WRITE)
56
57static DEFINE_PER_CPU(unsigned long, nfsd_file_cache_hits);
58static DEFINE_PER_CPU(unsigned long, nfsd_file_acquisitions);
59static DEFINE_PER_CPU(unsigned long, nfsd_file_releases);
60static DEFINE_PER_CPU(unsigned long, nfsd_file_total_age);
61static DEFINE_PER_CPU(unsigned long, nfsd_file_evictions);
62
63struct nfsd_fcache_disposal {
64 struct work_struct work;
65 spinlock_t lock;
66 struct list_head freeme;
67};
68
69static struct workqueue_struct *nfsd_filecache_wq __read_mostly;
70
71static struct kmem_cache *nfsd_file_slab;
72static struct kmem_cache *nfsd_file_mark_slab;
73static struct list_lru nfsd_file_lru;
74static unsigned long nfsd_file_flags;
75static struct fsnotify_group *nfsd_file_fsnotify_group;
76static struct delayed_work nfsd_filecache_laundrette;
77static struct rhashtable nfsd_file_rhash_tbl
78 ____cacheline_aligned_in_smp;
79
80enum nfsd_file_lookup_type {
81 NFSD_FILE_KEY_INODE,
82 NFSD_FILE_KEY_FULL,
83};
84
85struct nfsd_file_lookup_key {
86 struct inode *inode;
87 struct net *net;
88 const struct cred *cred;
89 unsigned char need;
90 bool gc;
91 enum nfsd_file_lookup_type type;
92};
93
94/*
95 * The returned hash value is based solely on the address of an in-code
96 * inode, a pointer to a slab-allocated object. The entropy in such a
97 * pointer is concentrated in its middle bits.
98 */
99static u32 nfsd_file_inode_hash(const struct inode *inode, u32 seed)
100{
101 unsigned long ptr = (unsigned long)inode;
102 u32 k;
103
104 k = ptr >> L1_CACHE_SHIFT;
105 k &= 0x00ffffff;
106 return jhash2(&k, 1, seed);
107}
108
109/**
110 * nfsd_file_key_hashfn - Compute the hash value of a lookup key
111 * @data: key on which to compute the hash value
112 * @len: rhash table's key_len parameter (unused)
113 * @seed: rhash table's random seed of the day
114 *
115 * Return value:
116 * Computed 32-bit hash value
117 */
118static u32 nfsd_file_key_hashfn(const void *data, u32 len, u32 seed)
119{
120 const struct nfsd_file_lookup_key *key = data;
121
122 return nfsd_file_inode_hash(key->inode, seed);
123}
124
125/**
126 * nfsd_file_obj_hashfn - Compute the hash value of an nfsd_file
127 * @data: object on which to compute the hash value
128 * @len: rhash table's key_len parameter (unused)
129 * @seed: rhash table's random seed of the day
130 *
131 * Return value:
132 * Computed 32-bit hash value
133 */
134static u32 nfsd_file_obj_hashfn(const void *data, u32 len, u32 seed)
135{
136 const struct nfsd_file *nf = data;
137
138 return nfsd_file_inode_hash(nf->nf_inode, seed);
139}
140
141static bool
142nfsd_match_cred(const struct cred *c1, const struct cred *c2)
143{
144 int i;
145
146 if (!uid_eq(c1->fsuid, c2->fsuid))
147 return false;
148 if (!gid_eq(c1->fsgid, c2->fsgid))
149 return false;
150 if (c1->group_info == NULL || c2->group_info == NULL)
151 return c1->group_info == c2->group_info;
152 if (c1->group_info->ngroups != c2->group_info->ngroups)
153 return false;
154 for (i = 0; i < c1->group_info->ngroups; i++) {
155 if (!gid_eq(c1->group_info->gid[i], c2->group_info->gid[i]))
156 return false;
157 }
158 return true;
159}
160
161/**
162 * nfsd_file_obj_cmpfn - Match a cache item against search criteria
163 * @arg: search criteria
164 * @ptr: cache item to check
165 *
166 * Return values:
167 * %0 - Item matches search criteria
168 * %1 - Item does not match search criteria
169 */
170static int nfsd_file_obj_cmpfn(struct rhashtable_compare_arg *arg,
171 const void *ptr)
172{
173 const struct nfsd_file_lookup_key *key = arg->key;
174 const struct nfsd_file *nf = ptr;
175
176 switch (key->type) {
177 case NFSD_FILE_KEY_INODE:
178 if (nf->nf_inode != key->inode)
179 return 1;
180 break;
181 case NFSD_FILE_KEY_FULL:
182 if (nf->nf_inode != key->inode)
183 return 1;
184 if (nf->nf_may != key->need)
185 return 1;
186 if (nf->nf_net != key->net)
187 return 1;
188 if (!nfsd_match_cred(nf->nf_cred, key->cred))
189 return 1;
190 if (!!test_bit(NFSD_FILE_GC, &nf->nf_flags) != key->gc)
191 return 1;
192 if (test_bit(NFSD_FILE_HASHED, &nf->nf_flags) == 0)
193 return 1;
194 break;
195 }
196 return 0;
197}
198
199static const struct rhashtable_params nfsd_file_rhash_params = {
200 .key_len = sizeof_field(struct nfsd_file, nf_inode),
201 .key_offset = offsetof(struct nfsd_file, nf_inode),
202 .head_offset = offsetof(struct nfsd_file, nf_rhash),
203 .hashfn = nfsd_file_key_hashfn,
204 .obj_hashfn = nfsd_file_obj_hashfn,
205 .obj_cmpfn = nfsd_file_obj_cmpfn,
206 /* Reduce resizing churn on light workloads */
207 .min_size = 512, /* buckets */
208 .automatic_shrinking = true,
209};
210
211static void
212nfsd_file_schedule_laundrette(void)
213{
214 if (test_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags))
215 queue_delayed_work(system_wq, &nfsd_filecache_laundrette,
216 NFSD_LAUNDRETTE_DELAY);
217}
218
219static void
220nfsd_file_slab_free(struct rcu_head *rcu)
221{
222 struct nfsd_file *nf = container_of(rcu, struct nfsd_file, nf_rcu);
223
224 put_cred(nf->nf_cred);
225 kmem_cache_free(nfsd_file_slab, nf);
226}
227
228static void
229nfsd_file_mark_free(struct fsnotify_mark *mark)
230{
231 struct nfsd_file_mark *nfm = container_of(mark, struct nfsd_file_mark,
232 nfm_mark);
233
234 kmem_cache_free(nfsd_file_mark_slab, nfm);
235}
236
237static struct nfsd_file_mark *
238nfsd_file_mark_get(struct nfsd_file_mark *nfm)
239{
240 if (!refcount_inc_not_zero(&nfm->nfm_ref))
241 return NULL;
242 return nfm;
243}
244
245static void
246nfsd_file_mark_put(struct nfsd_file_mark *nfm)
247{
248 if (refcount_dec_and_test(&nfm->nfm_ref)) {
249 fsnotify_destroy_mark(&nfm->nfm_mark, nfsd_file_fsnotify_group);
250 fsnotify_put_mark(&nfm->nfm_mark);
251 }
252}
253
254static struct nfsd_file_mark *
255nfsd_file_mark_find_or_create(struct nfsd_file *nf, struct inode *inode)
256{
257 int err;
258 struct fsnotify_mark *mark;
259 struct nfsd_file_mark *nfm = NULL, *new;
260
261 do {
262 fsnotify_group_lock(nfsd_file_fsnotify_group);
263 mark = fsnotify_find_mark(&inode->i_fsnotify_marks,
264 nfsd_file_fsnotify_group);
265 if (mark) {
266 nfm = nfsd_file_mark_get(container_of(mark,
267 struct nfsd_file_mark,
268 nfm_mark));
269 fsnotify_group_unlock(nfsd_file_fsnotify_group);
270 if (nfm) {
271 fsnotify_put_mark(mark);
272 break;
273 }
274 /* Avoid soft lockup race with nfsd_file_mark_put() */
275 fsnotify_destroy_mark(mark, nfsd_file_fsnotify_group);
276 fsnotify_put_mark(mark);
277 } else {
278 fsnotify_group_unlock(nfsd_file_fsnotify_group);
279 }
280
281 /* allocate a new nfm */
282 new = kmem_cache_alloc(nfsd_file_mark_slab, GFP_KERNEL);
283 if (!new)
284 return NULL;
285 fsnotify_init_mark(&new->nfm_mark, nfsd_file_fsnotify_group);
286 new->nfm_mark.mask = FS_ATTRIB|FS_DELETE_SELF;
287 refcount_set(&new->nfm_ref, 1);
288
289 err = fsnotify_add_inode_mark(&new->nfm_mark, inode, 0);
290
291 /*
292 * If the add was successful, then return the object.
293 * Otherwise, we need to put the reference we hold on the
294 * nfm_mark. The fsnotify code will take a reference and put
295 * it on failure, so we can't just free it directly. It's also
296 * not safe to call fsnotify_destroy_mark on it as the
297 * mark->group will be NULL. Thus, we can't let the nfm_ref
298 * counter drive the destruction at this point.
299 */
300 if (likely(!err))
301 nfm = new;
302 else
303 fsnotify_put_mark(&new->nfm_mark);
304 } while (unlikely(err == -EEXIST));
305
306 return nfm;
307}
308
309static struct nfsd_file *
310nfsd_file_alloc(struct nfsd_file_lookup_key *key, unsigned int may)
311{
312 struct nfsd_file *nf;
313
314 nf = kmem_cache_alloc(nfsd_file_slab, GFP_KERNEL);
315 if (nf) {
316 INIT_LIST_HEAD(&nf->nf_lru);
317 nf->nf_birthtime = ktime_get();
318 nf->nf_file = NULL;
319 nf->nf_cred = get_current_cred();
320 nf->nf_net = key->net;
321 nf->nf_flags = 0;
322 __set_bit(NFSD_FILE_HASHED, &nf->nf_flags);
323 __set_bit(NFSD_FILE_PENDING, &nf->nf_flags);
324 if (key->gc)
325 __set_bit(NFSD_FILE_GC, &nf->nf_flags);
326 nf->nf_inode = key->inode;
327 refcount_set(&nf->nf_ref, 1);
328 nf->nf_may = key->need;
329 nf->nf_mark = NULL;
330 }
331 return nf;
332}
333
334static void
335nfsd_file_fsync(struct nfsd_file *nf)
336{
337 struct file *file = nf->nf_file;
338 int ret;
339
340 if (!file || !(file->f_mode & FMODE_WRITE))
341 return;
342 ret = vfs_fsync(file, 1);
343 trace_nfsd_file_fsync(nf, ret);
344 if (ret)
345 nfsd_reset_write_verifier(net_generic(nf->nf_net, nfsd_net_id));
346}
347
348static int
349nfsd_file_check_write_error(struct nfsd_file *nf)
350{
351 struct file *file = nf->nf_file;
352
353 if (!file || !(file->f_mode & FMODE_WRITE))
354 return 0;
355 return filemap_check_wb_err(file->f_mapping, READ_ONCE(file->f_wb_err));
356}
357
358static void
359nfsd_file_hash_remove(struct nfsd_file *nf)
360{
361 trace_nfsd_file_unhash(nf);
362
363 if (nfsd_file_check_write_error(nf))
364 nfsd_reset_write_verifier(net_generic(nf->nf_net, nfsd_net_id));
365 rhashtable_remove_fast(&nfsd_file_rhash_tbl, &nf->nf_rhash,
366 nfsd_file_rhash_params);
367}
368
369static bool
370nfsd_file_unhash(struct nfsd_file *nf)
371{
372 if (test_and_clear_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
373 nfsd_file_hash_remove(nf);
374 return true;
375 }
376 return false;
377}
378
379static void
380nfsd_file_free(struct nfsd_file *nf)
381{
382 s64 age = ktime_to_ms(ktime_sub(ktime_get(), nf->nf_birthtime));
383
384 trace_nfsd_file_free(nf);
385
386 this_cpu_inc(nfsd_file_releases);
387 this_cpu_add(nfsd_file_total_age, age);
388
389 nfsd_file_unhash(nf);
390
391 /*
392 * We call fsync here in order to catch writeback errors. It's not
393 * strictly required by the protocol, but an nfsd_file could get
394 * evicted from the cache before a COMMIT comes in. If another
395 * task were to open that file in the interim and scrape the error,
396 * then the client may never see it. By calling fsync here, we ensure
397 * that writeback happens before the entry is freed, and that any
398 * errors reported result in the write verifier changing.
399 */
400 nfsd_file_fsync(nf);
401
402 if (nf->nf_mark)
403 nfsd_file_mark_put(nf->nf_mark);
404 if (nf->nf_file) {
405 get_file(nf->nf_file);
406 filp_close(nf->nf_file, NULL);
407 fput(nf->nf_file);
408 }
409
410 /*
411 * If this item is still linked via nf_lru, that's a bug.
412 * WARN and leak it to preserve system stability.
413 */
414 if (WARN_ON_ONCE(!list_empty(&nf->nf_lru)))
415 return;
416
417 call_rcu(&nf->nf_rcu, nfsd_file_slab_free);
418}
419
420static bool
421nfsd_file_check_writeback(struct nfsd_file *nf)
422{
423 struct file *file = nf->nf_file;
424 struct address_space *mapping;
425
426 if (!file || !(file->f_mode & FMODE_WRITE))
427 return false;
428 mapping = file->f_mapping;
429 return mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) ||
430 mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK);
431}
432
433static bool nfsd_file_lru_add(struct nfsd_file *nf)
434{
435 set_bit(NFSD_FILE_REFERENCED, &nf->nf_flags);
436 if (list_lru_add(&nfsd_file_lru, &nf->nf_lru)) {
437 trace_nfsd_file_lru_add(nf);
438 return true;
439 }
440 return false;
441}
442
443static bool nfsd_file_lru_remove(struct nfsd_file *nf)
444{
445 if (list_lru_del(&nfsd_file_lru, &nf->nf_lru)) {
446 trace_nfsd_file_lru_del(nf);
447 return true;
448 }
449 return false;
450}
451
452struct nfsd_file *
453nfsd_file_get(struct nfsd_file *nf)
454{
455 if (likely(refcount_inc_not_zero(&nf->nf_ref)))
456 return nf;
457 return NULL;
458}
459
460/**
461 * nfsd_file_put - put the reference to a nfsd_file
462 * @nf: nfsd_file of which to put the reference
463 *
464 * Put a reference to a nfsd_file. In the non-GC case, we just put the
465 * reference immediately. In the GC case, if the reference would be
466 * the last one, the put it on the LRU instead to be cleaned up later.
467 */
468void
469nfsd_file_put(struct nfsd_file *nf)
470{
471 might_sleep();
472 trace_nfsd_file_put(nf);
473
474 if (test_bit(NFSD_FILE_GC, &nf->nf_flags) &&
475 test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
476 /*
477 * If this is the last reference (nf_ref == 1), then try to
478 * transfer it to the LRU.
479 */
480 if (refcount_dec_not_one(&nf->nf_ref))
481 return;
482
483 /* Try to add it to the LRU. If that fails, decrement. */
484 if (nfsd_file_lru_add(nf)) {
485 /* If it's still hashed, we're done */
486 if (test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
487 nfsd_file_schedule_laundrette();
488 return;
489 }
490
491 /*
492 * We're racing with unhashing, so try to remove it from
493 * the LRU. If removal fails, then someone else already
494 * has our reference.
495 */
496 if (!nfsd_file_lru_remove(nf))
497 return;
498 }
499 }
500 if (refcount_dec_and_test(&nf->nf_ref))
501 nfsd_file_free(nf);
502}
503
504static void
505nfsd_file_dispose_list(struct list_head *dispose)
506{
507 struct nfsd_file *nf;
508
509 while (!list_empty(dispose)) {
510 nf = list_first_entry(dispose, struct nfsd_file, nf_lru);
511 list_del_init(&nf->nf_lru);
512 nfsd_file_free(nf);
513 }
514}
515
516static void
517nfsd_file_list_remove_disposal(struct list_head *dst,
518 struct nfsd_fcache_disposal *l)
519{
520 spin_lock(&l->lock);
521 list_splice_init(&l->freeme, dst);
522 spin_unlock(&l->lock);
523}
524
525static void
526nfsd_file_list_add_disposal(struct list_head *files, struct net *net)
527{
528 struct nfsd_net *nn = net_generic(net, nfsd_net_id);
529 struct nfsd_fcache_disposal *l = nn->fcache_disposal;
530
531 spin_lock(&l->lock);
532 list_splice_tail_init(files, &l->freeme);
533 spin_unlock(&l->lock);
534 queue_work(nfsd_filecache_wq, &l->work);
535}
536
537static void
538nfsd_file_list_add_pernet(struct list_head *dst, struct list_head *src,
539 struct net *net)
540{
541 struct nfsd_file *nf, *tmp;
542
543 list_for_each_entry_safe(nf, tmp, src, nf_lru) {
544 if (nf->nf_net == net)
545 list_move_tail(&nf->nf_lru, dst);
546 }
547}
548
549static void
550nfsd_file_dispose_list_delayed(struct list_head *dispose)
551{
552 LIST_HEAD(list);
553 struct nfsd_file *nf;
554
555 while(!list_empty(dispose)) {
556 nf = list_first_entry(dispose, struct nfsd_file, nf_lru);
557 nfsd_file_list_add_pernet(&list, dispose, nf->nf_net);
558 nfsd_file_list_add_disposal(&list, nf->nf_net);
559 }
560}
561
562/**
563 * nfsd_file_lru_cb - Examine an entry on the LRU list
564 * @item: LRU entry to examine
565 * @lru: controlling LRU
566 * @lock: LRU list lock (unused)
567 * @arg: dispose list
568 *
569 * Return values:
570 * %LRU_REMOVED: @item was removed from the LRU
571 * %LRU_ROTATE: @item is to be moved to the LRU tail
572 * %LRU_SKIP: @item cannot be evicted
573 */
574static enum lru_status
575nfsd_file_lru_cb(struct list_head *item, struct list_lru_one *lru,
576 spinlock_t *lock, void *arg)
577 __releases(lock)
578 __acquires(lock)
579{
580 struct list_head *head = arg;
581 struct nfsd_file *nf = list_entry(item, struct nfsd_file, nf_lru);
582
583 /* We should only be dealing with GC entries here */
584 WARN_ON_ONCE(!test_bit(NFSD_FILE_GC, &nf->nf_flags));
585
586 /*
587 * Don't throw out files that are still undergoing I/O or
588 * that have uncleared errors pending.
589 */
590 if (nfsd_file_check_writeback(nf)) {
591 trace_nfsd_file_gc_writeback(nf);
592 return LRU_SKIP;
593 }
594
595 /* If it was recently added to the list, skip it */
596 if (test_and_clear_bit(NFSD_FILE_REFERENCED, &nf->nf_flags)) {
597 trace_nfsd_file_gc_referenced(nf);
598 return LRU_ROTATE;
599 }
600
601 /*
602 * Put the reference held on behalf of the LRU. If it wasn't the last
603 * one, then just remove it from the LRU and ignore it.
604 */
605 if (!refcount_dec_and_test(&nf->nf_ref)) {
606 trace_nfsd_file_gc_in_use(nf);
607 list_lru_isolate(lru, &nf->nf_lru);
608 return LRU_REMOVED;
609 }
610
611 /* Refcount went to zero. Unhash it and queue it to the dispose list */
612 nfsd_file_unhash(nf);
613 list_lru_isolate_move(lru, &nf->nf_lru, head);
614 this_cpu_inc(nfsd_file_evictions);
615 trace_nfsd_file_gc_disposed(nf);
616 return LRU_REMOVED;
617}
618
619static void
620nfsd_file_gc(void)
621{
622 LIST_HEAD(dispose);
623 unsigned long ret;
624
625 ret = list_lru_walk(&nfsd_file_lru, nfsd_file_lru_cb,
626 &dispose, list_lru_count(&nfsd_file_lru));
627 trace_nfsd_file_gc_removed(ret, list_lru_count(&nfsd_file_lru));
628 nfsd_file_dispose_list_delayed(&dispose);
629}
630
631static void
632nfsd_file_gc_worker(struct work_struct *work)
633{
634 nfsd_file_gc();
635 if (list_lru_count(&nfsd_file_lru))
636 nfsd_file_schedule_laundrette();
637}
638
639static unsigned long
640nfsd_file_lru_count(struct shrinker *s, struct shrink_control *sc)
641{
642 return list_lru_count(&nfsd_file_lru);
643}
644
645static unsigned long
646nfsd_file_lru_scan(struct shrinker *s, struct shrink_control *sc)
647{
648 LIST_HEAD(dispose);
649 unsigned long ret;
650
651 ret = list_lru_shrink_walk(&nfsd_file_lru, sc,
652 nfsd_file_lru_cb, &dispose);
653 trace_nfsd_file_shrinker_removed(ret, list_lru_count(&nfsd_file_lru));
654 nfsd_file_dispose_list_delayed(&dispose);
655 return ret;
656}
657
658static struct shrinker nfsd_file_shrinker = {
659 .scan_objects = nfsd_file_lru_scan,
660 .count_objects = nfsd_file_lru_count,
661 .seeks = 1,
662};
663
664/**
665 * nfsd_file_cond_queue - conditionally unhash and queue a nfsd_file
666 * @nf: nfsd_file to attempt to queue
667 * @dispose: private list to queue successfully-put objects
668 *
669 * Unhash an nfsd_file, try to get a reference to it, and then put that
670 * reference. If it's the last reference, queue it to the dispose list.
671 */
672static void
673nfsd_file_cond_queue(struct nfsd_file *nf, struct list_head *dispose)
674 __must_hold(RCU)
675{
676 int decrement = 1;
677
678 /* If we raced with someone else unhashing, ignore it */
679 if (!nfsd_file_unhash(nf))
680 return;
681
682 /* If we can't get a reference, ignore it */
683 if (!nfsd_file_get(nf))
684 return;
685
686 /* Extra decrement if we remove from the LRU */
687 if (nfsd_file_lru_remove(nf))
688 ++decrement;
689
690 /* If refcount goes to 0, then put on the dispose list */
691 if (refcount_sub_and_test(decrement, &nf->nf_ref)) {
692 list_add(&nf->nf_lru, dispose);
693 trace_nfsd_file_closing(nf);
694 }
695}
696
697/**
698 * nfsd_file_queue_for_close: try to close out any open nfsd_files for an inode
699 * @inode: inode on which to close out nfsd_files
700 * @dispose: list on which to gather nfsd_files to close out
701 *
702 * An nfsd_file represents a struct file being held open on behalf of nfsd. An
703 * open file however can block other activity (such as leases), or cause
704 * undesirable behavior (e.g. spurious silly-renames when reexporting NFS).
705 *
706 * This function is intended to find open nfsd_files when this sort of
707 * conflicting access occurs and then attempt to close those files out.
708 *
709 * Populates the dispose list with entries that have already had their
710 * refcounts go to zero. The actual free of an nfsd_file can be expensive,
711 * so we leave it up to the caller whether it wants to wait or not.
712 */
713static void
714nfsd_file_queue_for_close(struct inode *inode, struct list_head *dispose)
715{
716 struct nfsd_file_lookup_key key = {
717 .type = NFSD_FILE_KEY_INODE,
718 .inode = inode,
719 };
720 struct nfsd_file *nf;
721
722 rcu_read_lock();
723 do {
724 nf = rhashtable_lookup(&nfsd_file_rhash_tbl, &key,
725 nfsd_file_rhash_params);
726 if (!nf)
727 break;
728 nfsd_file_cond_queue(nf, dispose);
729 } while (1);
730 rcu_read_unlock();
731}
732
733/**
734 * nfsd_file_close_inode - attempt a delayed close of a nfsd_file
735 * @inode: inode of the file to attempt to remove
736 *
737 * Close out any open nfsd_files that can be reaped for @inode. The
738 * actual freeing is deferred to the dispose_list_delayed infrastructure.
739 *
740 * This is used by the fsnotify callbacks and setlease notifier.
741 */
742static void
743nfsd_file_close_inode(struct inode *inode)
744{
745 LIST_HEAD(dispose);
746
747 nfsd_file_queue_for_close(inode, &dispose);
748 nfsd_file_dispose_list_delayed(&dispose);
749}
750
751/**
752 * nfsd_file_close_inode_sync - attempt to forcibly close a nfsd_file
753 * @inode: inode of the file to attempt to remove
754 *
755 * Close out any open nfsd_files that can be reaped for @inode. The
756 * nfsd_files are closed out synchronously.
757 *
758 * This is called from nfsd_rename and nfsd_unlink to avoid silly-renames
759 * when reexporting NFS.
760 */
761void
762nfsd_file_close_inode_sync(struct inode *inode)
763{
764 struct nfsd_file *nf;
765 LIST_HEAD(dispose);
766
767 trace_nfsd_file_close(inode);
768
769 nfsd_file_queue_for_close(inode, &dispose);
770 while (!list_empty(&dispose)) {
771 nf = list_first_entry(&dispose, struct nfsd_file, nf_lru);
772 list_del_init(&nf->nf_lru);
773 nfsd_file_free(nf);
774 }
775 flush_delayed_fput();
776}
777
778/**
779 * nfsd_file_delayed_close - close unused nfsd_files
780 * @work: dummy
781 *
782 * Walk the LRU list and destroy any entries that have not been used since
783 * the last scan.
784 */
785static void
786nfsd_file_delayed_close(struct work_struct *work)
787{
788 LIST_HEAD(head);
789 struct nfsd_fcache_disposal *l = container_of(work,
790 struct nfsd_fcache_disposal, work);
791
792 nfsd_file_list_remove_disposal(&head, l);
793 nfsd_file_dispose_list(&head);
794}
795
796static int
797nfsd_file_lease_notifier_call(struct notifier_block *nb, unsigned long arg,
798 void *data)
799{
800 struct file_lock *fl = data;
801
802 /* Only close files for F_SETLEASE leases */
803 if (fl->fl_flags & FL_LEASE)
804 nfsd_file_close_inode(file_inode(fl->fl_file));
805 return 0;
806}
807
808static struct notifier_block nfsd_file_lease_notifier = {
809 .notifier_call = nfsd_file_lease_notifier_call,
810};
811
812static int
813nfsd_file_fsnotify_handle_event(struct fsnotify_mark *mark, u32 mask,
814 struct inode *inode, struct inode *dir,
815 const struct qstr *name, u32 cookie)
816{
817 if (WARN_ON_ONCE(!inode))
818 return 0;
819
820 trace_nfsd_file_fsnotify_handle_event(inode, mask);
821
822 /* Should be no marks on non-regular files */
823 if (!S_ISREG(inode->i_mode)) {
824 WARN_ON_ONCE(1);
825 return 0;
826 }
827
828 /* don't close files if this was not the last link */
829 if (mask & FS_ATTRIB) {
830 if (inode->i_nlink)
831 return 0;
832 }
833
834 nfsd_file_close_inode(inode);
835 return 0;
836}
837
838
839static const struct fsnotify_ops nfsd_file_fsnotify_ops = {
840 .handle_inode_event = nfsd_file_fsnotify_handle_event,
841 .free_mark = nfsd_file_mark_free,
842};
843
844int
845nfsd_file_cache_init(void)
846{
847 int ret;
848
849 lockdep_assert_held(&nfsd_mutex);
850 if (test_and_set_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags) == 1)
851 return 0;
852
853 ret = rhashtable_init(&nfsd_file_rhash_tbl, &nfsd_file_rhash_params);
854 if (ret)
855 return ret;
856
857 ret = -ENOMEM;
858 nfsd_filecache_wq = alloc_workqueue("nfsd_filecache", 0, 0);
859 if (!nfsd_filecache_wq)
860 goto out;
861
862 nfsd_file_slab = kmem_cache_create("nfsd_file",
863 sizeof(struct nfsd_file), 0, 0, NULL);
864 if (!nfsd_file_slab) {
865 pr_err("nfsd: unable to create nfsd_file_slab\n");
866 goto out_err;
867 }
868
869 nfsd_file_mark_slab = kmem_cache_create("nfsd_file_mark",
870 sizeof(struct nfsd_file_mark), 0, 0, NULL);
871 if (!nfsd_file_mark_slab) {
872 pr_err("nfsd: unable to create nfsd_file_mark_slab\n");
873 goto out_err;
874 }
875
876
877 ret = list_lru_init(&nfsd_file_lru);
878 if (ret) {
879 pr_err("nfsd: failed to init nfsd_file_lru: %d\n", ret);
880 goto out_err;
881 }
882
883 ret = register_shrinker(&nfsd_file_shrinker, "nfsd-filecache");
884 if (ret) {
885 pr_err("nfsd: failed to register nfsd_file_shrinker: %d\n", ret);
886 goto out_lru;
887 }
888
889 ret = lease_register_notifier(&nfsd_file_lease_notifier);
890 if (ret) {
891 pr_err("nfsd: unable to register lease notifier: %d\n", ret);
892 goto out_shrinker;
893 }
894
895 nfsd_file_fsnotify_group = fsnotify_alloc_group(&nfsd_file_fsnotify_ops,
896 FSNOTIFY_GROUP_NOFS);
897 if (IS_ERR(nfsd_file_fsnotify_group)) {
898 pr_err("nfsd: unable to create fsnotify group: %ld\n",
899 PTR_ERR(nfsd_file_fsnotify_group));
900 ret = PTR_ERR(nfsd_file_fsnotify_group);
901 nfsd_file_fsnotify_group = NULL;
902 goto out_notifier;
903 }
904
905 INIT_DELAYED_WORK(&nfsd_filecache_laundrette, nfsd_file_gc_worker);
906out:
907 return ret;
908out_notifier:
909 lease_unregister_notifier(&nfsd_file_lease_notifier);
910out_shrinker:
911 unregister_shrinker(&nfsd_file_shrinker);
912out_lru:
913 list_lru_destroy(&nfsd_file_lru);
914out_err:
915 kmem_cache_destroy(nfsd_file_slab);
916 nfsd_file_slab = NULL;
917 kmem_cache_destroy(nfsd_file_mark_slab);
918 nfsd_file_mark_slab = NULL;
919 destroy_workqueue(nfsd_filecache_wq);
920 nfsd_filecache_wq = NULL;
921 rhashtable_destroy(&nfsd_file_rhash_tbl);
922 goto out;
923}
924
925/**
926 * __nfsd_file_cache_purge: clean out the cache for shutdown
927 * @net: net-namespace to shut down the cache (may be NULL)
928 *
929 * Walk the nfsd_file cache and close out any that match @net. If @net is NULL,
930 * then close out everything. Called when an nfsd instance is being shut down.
931 */
932static void
933__nfsd_file_cache_purge(struct net *net)
934{
935 struct rhashtable_iter iter;
936 struct nfsd_file *nf;
937 LIST_HEAD(dispose);
938
939 rhashtable_walk_enter(&nfsd_file_rhash_tbl, &iter);
940 do {
941 rhashtable_walk_start(&iter);
942
943 nf = rhashtable_walk_next(&iter);
944 while (!IS_ERR_OR_NULL(nf)) {
945 if (!net || nf->nf_net == net)
946 nfsd_file_cond_queue(nf, &dispose);
947 nf = rhashtable_walk_next(&iter);
948 }
949
950 rhashtable_walk_stop(&iter);
951 } while (nf == ERR_PTR(-EAGAIN));
952 rhashtable_walk_exit(&iter);
953
954 nfsd_file_dispose_list(&dispose);
955}
956
957static struct nfsd_fcache_disposal *
958nfsd_alloc_fcache_disposal(void)
959{
960 struct nfsd_fcache_disposal *l;
961
962 l = kmalloc(sizeof(*l), GFP_KERNEL);
963 if (!l)
964 return NULL;
965 INIT_WORK(&l->work, nfsd_file_delayed_close);
966 spin_lock_init(&l->lock);
967 INIT_LIST_HEAD(&l->freeme);
968 return l;
969}
970
971static void
972nfsd_free_fcache_disposal(struct nfsd_fcache_disposal *l)
973{
974 cancel_work_sync(&l->work);
975 nfsd_file_dispose_list(&l->freeme);
976 kfree(l);
977}
978
979static void
980nfsd_free_fcache_disposal_net(struct net *net)
981{
982 struct nfsd_net *nn = net_generic(net, nfsd_net_id);
983 struct nfsd_fcache_disposal *l = nn->fcache_disposal;
984
985 nfsd_free_fcache_disposal(l);
986}
987
988int
989nfsd_file_cache_start_net(struct net *net)
990{
991 struct nfsd_net *nn = net_generic(net, nfsd_net_id);
992
993 nn->fcache_disposal = nfsd_alloc_fcache_disposal();
994 return nn->fcache_disposal ? 0 : -ENOMEM;
995}
996
997/**
998 * nfsd_file_cache_purge - Remove all cache items associated with @net
999 * @net: target net namespace
1000 *
1001 */
1002void
1003nfsd_file_cache_purge(struct net *net)
1004{
1005 lockdep_assert_held(&nfsd_mutex);
1006 if (test_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags) == 1)
1007 __nfsd_file_cache_purge(net);
1008}
1009
1010void
1011nfsd_file_cache_shutdown_net(struct net *net)
1012{
1013 nfsd_file_cache_purge(net);
1014 nfsd_free_fcache_disposal_net(net);
1015}
1016
1017void
1018nfsd_file_cache_shutdown(void)
1019{
1020 int i;
1021
1022 lockdep_assert_held(&nfsd_mutex);
1023 if (test_and_clear_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags) == 0)
1024 return;
1025
1026 lease_unregister_notifier(&nfsd_file_lease_notifier);
1027 unregister_shrinker(&nfsd_file_shrinker);
1028 /*
1029 * make sure all callers of nfsd_file_lru_cb are done before
1030 * calling nfsd_file_cache_purge
1031 */
1032 cancel_delayed_work_sync(&nfsd_filecache_laundrette);
1033 __nfsd_file_cache_purge(NULL);
1034 list_lru_destroy(&nfsd_file_lru);
1035 rcu_barrier();
1036 fsnotify_put_group(nfsd_file_fsnotify_group);
1037 nfsd_file_fsnotify_group = NULL;
1038 kmem_cache_destroy(nfsd_file_slab);
1039 nfsd_file_slab = NULL;
1040 fsnotify_wait_marks_destroyed();
1041 kmem_cache_destroy(nfsd_file_mark_slab);
1042 nfsd_file_mark_slab = NULL;
1043 destroy_workqueue(nfsd_filecache_wq);
1044 nfsd_filecache_wq = NULL;
1045 rhashtable_destroy(&nfsd_file_rhash_tbl);
1046
1047 for_each_possible_cpu(i) {
1048 per_cpu(nfsd_file_cache_hits, i) = 0;
1049 per_cpu(nfsd_file_acquisitions, i) = 0;
1050 per_cpu(nfsd_file_releases, i) = 0;
1051 per_cpu(nfsd_file_total_age, i) = 0;
1052 per_cpu(nfsd_file_evictions, i) = 0;
1053 }
1054}
1055
1056/**
1057 * nfsd_file_is_cached - are there any cached open files for this inode?
1058 * @inode: inode to check
1059 *
1060 * The lookup matches inodes in all net namespaces and is atomic wrt
1061 * nfsd_file_acquire().
1062 *
1063 * Return values:
1064 * %true: filecache contains at least one file matching this inode
1065 * %false: filecache contains no files matching this inode
1066 */
1067bool
1068nfsd_file_is_cached(struct inode *inode)
1069{
1070 struct nfsd_file_lookup_key key = {
1071 .type = NFSD_FILE_KEY_INODE,
1072 .inode = inode,
1073 };
1074 bool ret = false;
1075
1076 if (rhashtable_lookup_fast(&nfsd_file_rhash_tbl, &key,
1077 nfsd_file_rhash_params) != NULL)
1078 ret = true;
1079 trace_nfsd_file_is_cached(inode, (int)ret);
1080 return ret;
1081}
1082
1083static __be32
1084nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
1085 unsigned int may_flags, struct file *file,
1086 struct nfsd_file **pnf, bool want_gc)
1087{
1088 struct nfsd_file_lookup_key key = {
1089 .type = NFSD_FILE_KEY_FULL,
1090 .need = may_flags & NFSD_FILE_MAY_MASK,
1091 .net = SVC_NET(rqstp),
1092 .gc = want_gc,
1093 };
1094 bool open_retry = true;
1095 struct nfsd_file *nf;
1096 __be32 status;
1097 int ret;
1098
1099 status = fh_verify(rqstp, fhp, S_IFREG,
1100 may_flags|NFSD_MAY_OWNER_OVERRIDE);
1101 if (status != nfs_ok)
1102 return status;
1103 key.inode = d_inode(fhp->fh_dentry);
1104 key.cred = get_current_cred();
1105
1106retry:
1107 rcu_read_lock();
1108 nf = rhashtable_lookup(&nfsd_file_rhash_tbl, &key,
1109 nfsd_file_rhash_params);
1110 if (nf)
1111 nf = nfsd_file_get(nf);
1112 rcu_read_unlock();
1113
1114 if (nf) {
1115 if (nfsd_file_lru_remove(nf))
1116 WARN_ON_ONCE(refcount_dec_and_test(&nf->nf_ref));
1117 goto wait_for_construction;
1118 }
1119
1120 nf = nfsd_file_alloc(&key, may_flags);
1121 if (!nf) {
1122 status = nfserr_jukebox;
1123 goto out_status;
1124 }
1125
1126 ret = rhashtable_lookup_insert_key(&nfsd_file_rhash_tbl,
1127 &key, &nf->nf_rhash,
1128 nfsd_file_rhash_params);
1129 if (likely(ret == 0))
1130 goto open_file;
1131
1132 nfsd_file_slab_free(&nf->nf_rcu);
1133 nf = NULL;
1134 if (ret == -EEXIST)
1135 goto retry;
1136 trace_nfsd_file_insert_err(rqstp, key.inode, may_flags, ret);
1137 status = nfserr_jukebox;
1138 goto out_status;
1139
1140wait_for_construction:
1141 wait_on_bit(&nf->nf_flags, NFSD_FILE_PENDING, TASK_UNINTERRUPTIBLE);
1142
1143 /* Did construction of this file fail? */
1144 if (!test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
1145 trace_nfsd_file_cons_err(rqstp, key.inode, may_flags, nf);
1146 if (!open_retry) {
1147 status = nfserr_jukebox;
1148 goto out;
1149 }
1150 open_retry = false;
1151 if (refcount_dec_and_test(&nf->nf_ref))
1152 nfsd_file_free(nf);
1153 goto retry;
1154 }
1155
1156 this_cpu_inc(nfsd_file_cache_hits);
1157
1158 status = nfserrno(nfsd_open_break_lease(file_inode(nf->nf_file), may_flags));
1159out:
1160 if (status == nfs_ok) {
1161 this_cpu_inc(nfsd_file_acquisitions);
1162 *pnf = nf;
1163 } else {
1164 if (refcount_dec_and_test(&nf->nf_ref))
1165 nfsd_file_free(nf);
1166 nf = NULL;
1167 }
1168
1169out_status:
1170 put_cred(key.cred);
1171 trace_nfsd_file_acquire(rqstp, key.inode, may_flags, nf, status);
1172 return status;
1173
1174open_file:
1175 trace_nfsd_file_alloc(nf);
1176 nf->nf_mark = nfsd_file_mark_find_or_create(nf, key.inode);
1177 if (nf->nf_mark) {
1178 if (file) {
1179 get_file(file);
1180 nf->nf_file = file;
1181 status = nfs_ok;
1182 trace_nfsd_file_opened(nf, status);
1183 } else {
1184 status = nfsd_open_verified(rqstp, fhp, may_flags,
1185 &nf->nf_file);
1186 trace_nfsd_file_open(nf, status);
1187 }
1188 } else
1189 status = nfserr_jukebox;
1190 /*
1191 * If construction failed, or we raced with a call to unlink()
1192 * then unhash.
1193 */
1194 if (status == nfs_ok && key.inode->i_nlink == 0)
1195 status = nfserr_jukebox;
1196 if (status != nfs_ok)
1197 nfsd_file_unhash(nf);
1198 clear_bit_unlock(NFSD_FILE_PENDING, &nf->nf_flags);
1199 smp_mb__after_atomic();
1200 wake_up_bit(&nf->nf_flags, NFSD_FILE_PENDING);
1201 goto out;
1202}
1203
1204/**
1205 * nfsd_file_acquire_gc - Get a struct nfsd_file with an open file
1206 * @rqstp: the RPC transaction being executed
1207 * @fhp: the NFS filehandle of the file to be opened
1208 * @may_flags: NFSD_MAY_ settings for the file
1209 * @pnf: OUT: new or found "struct nfsd_file" object
1210 *
1211 * The nfsd_file object returned by this API is reference-counted
1212 * and garbage-collected. The object is retained for a few
1213 * seconds after the final nfsd_file_put() in case the caller
1214 * wants to re-use it.
1215 *
1216 * Returns nfs_ok and sets @pnf on success; otherwise an nfsstat in
1217 * network byte order is returned.
1218 */
1219__be32
1220nfsd_file_acquire_gc(struct svc_rqst *rqstp, struct svc_fh *fhp,
1221 unsigned int may_flags, struct nfsd_file **pnf)
1222{
1223 return nfsd_file_do_acquire(rqstp, fhp, may_flags, NULL, pnf, true);
1224}
1225
1226/**
1227 * nfsd_file_acquire - Get a struct nfsd_file with an open file
1228 * @rqstp: the RPC transaction being executed
1229 * @fhp: the NFS filehandle of the file to be opened
1230 * @may_flags: NFSD_MAY_ settings for the file
1231 * @pnf: OUT: new or found "struct nfsd_file" object
1232 *
1233 * The nfsd_file_object returned by this API is reference-counted
1234 * but not garbage-collected. The object is unhashed after the
1235 * final nfsd_file_put().
1236 *
1237 * Returns nfs_ok and sets @pnf on success; otherwise an nfsstat in
1238 * network byte order is returned.
1239 */
1240__be32
1241nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
1242 unsigned int may_flags, struct nfsd_file **pnf)
1243{
1244 return nfsd_file_do_acquire(rqstp, fhp, may_flags, NULL, pnf, false);
1245}
1246
1247/**
1248 * nfsd_file_acquire_opened - Get a struct nfsd_file using existing open file
1249 * @rqstp: the RPC transaction being executed
1250 * @fhp: the NFS filehandle of the file just created
1251 * @may_flags: NFSD_MAY_ settings for the file
1252 * @file: cached, already-open file (may be NULL)
1253 * @pnf: OUT: new or found "struct nfsd_file" object
1254 *
1255 * Acquire a nfsd_file object that is not GC'ed. If one doesn't already exist,
1256 * and @file is non-NULL, use it to instantiate a new nfsd_file instead of
1257 * opening a new one.
1258 *
1259 * Returns nfs_ok and sets @pnf on success; otherwise an nfsstat in
1260 * network byte order is returned.
1261 */
1262__be32
1263nfsd_file_acquire_opened(struct svc_rqst *rqstp, struct svc_fh *fhp,
1264 unsigned int may_flags, struct file *file,
1265 struct nfsd_file **pnf)
1266{
1267 return nfsd_file_do_acquire(rqstp, fhp, may_flags, file, pnf, false);
1268}
1269
1270/*
1271 * Note that fields may be added, removed or reordered in the future. Programs
1272 * scraping this file for info should test the labels to ensure they're
1273 * getting the correct field.
1274 */
1275int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
1276{
1277 unsigned long releases = 0, evictions = 0;
1278 unsigned long hits = 0, acquisitions = 0;
1279 unsigned int i, count = 0, buckets = 0;
1280 unsigned long lru = 0, total_age = 0;
1281
1282 /* Serialize with server shutdown */
1283 mutex_lock(&nfsd_mutex);
1284 if (test_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags) == 1) {
1285 struct bucket_table *tbl;
1286 struct rhashtable *ht;
1287
1288 lru = list_lru_count(&nfsd_file_lru);
1289
1290 rcu_read_lock();
1291 ht = &nfsd_file_rhash_tbl;
1292 count = atomic_read(&ht->nelems);
1293 tbl = rht_dereference_rcu(ht->tbl, ht);
1294 buckets = tbl->size;
1295 rcu_read_unlock();
1296 }
1297 mutex_unlock(&nfsd_mutex);
1298
1299 for_each_possible_cpu(i) {
1300 hits += per_cpu(nfsd_file_cache_hits, i);
1301 acquisitions += per_cpu(nfsd_file_acquisitions, i);
1302 releases += per_cpu(nfsd_file_releases, i);
1303 total_age += per_cpu(nfsd_file_total_age, i);
1304 evictions += per_cpu(nfsd_file_evictions, i);
1305 }
1306
1307 seq_printf(m, "total entries: %u\n", count);
1308 seq_printf(m, "hash buckets: %u\n", buckets);
1309 seq_printf(m, "lru entries: %lu\n", lru);
1310 seq_printf(m, "cache hits: %lu\n", hits);
1311 seq_printf(m, "acquisitions: %lu\n", acquisitions);
1312 seq_printf(m, "releases: %lu\n", releases);
1313 seq_printf(m, "evictions: %lu\n", evictions);
1314 if (releases)
1315 seq_printf(m, "mean age (ms): %ld\n", total_age / releases);
1316 else
1317 seq_printf(m, "mean age (ms): -\n");
1318 return 0;
1319}