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1 /*
2  * net/sunrpc/cache.c
3  *
4  * Generic code for various authentication-related caches
5  * used by sunrpc clients and servers.
6  *
7  * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
8  *
9  * Released under terms in GPL version 2.  See COPYING.
10  *
11  */
12 
13 #include <linux/types.h>
14 #include <linux/fs.h>
15 #include <linux/file.h>
16 #include <linux/slab.h>
17 #include <linux/signal.h>
18 #include <linux/sched.h>
19 #include <linux/kmod.h>
20 #include <linux/list.h>
21 #include <linux/module.h>
22 #include <linux/ctype.h>
23 #include <linux/string_helpers.h>
24 #include <asm/uaccess.h>
25 #include <linux/poll.h>
26 #include <linux/seq_file.h>
27 #include <linux/proc_fs.h>
28 #include <linux/net.h>
29 #include <linux/workqueue.h>
30 #include <linux/mutex.h>
31 #include <linux/pagemap.h>
32 #include <asm/ioctls.h>
33 #include <linux/sunrpc/types.h>
34 #include <linux/sunrpc/cache.h>
35 #include <linux/sunrpc/stats.h>
36 #include <linux/sunrpc/rpc_pipe_fs.h>
37 #include "netns.h"
38 
39 #define	 RPCDBG_FACILITY RPCDBG_CACHE
40 
41 static bool cache_defer_req(struct cache_req *req, struct cache_head *item);
42 static void cache_revisit_request(struct cache_head *item);
43 
cache_init(struct cache_head * h,struct cache_detail * detail)44 static void cache_init(struct cache_head *h, struct cache_detail *detail)
45 {
46 	time_t now = seconds_since_boot();
47 	INIT_HLIST_NODE(&h->cache_list);
48 	h->flags = 0;
49 	kref_init(&h->ref);
50 	h->expiry_time = now + CACHE_NEW_EXPIRY;
51 	if (now <= detail->flush_time)
52 		/* ensure it isn't already expired */
53 		now = detail->flush_time + 1;
54 	h->last_refresh = now;
55 }
56 
sunrpc_cache_lookup(struct cache_detail * detail,struct cache_head * key,int hash)57 struct cache_head *sunrpc_cache_lookup(struct cache_detail *detail,
58 				       struct cache_head *key, int hash)
59 {
60 	struct cache_head *new = NULL, *freeme = NULL, *tmp = NULL;
61 	struct hlist_head *head;
62 
63 	head = &detail->hash_table[hash];
64 
65 	read_lock(&detail->hash_lock);
66 
67 	hlist_for_each_entry(tmp, head, cache_list) {
68 		if (detail->match(tmp, key)) {
69 			if (cache_is_expired(detail, tmp))
70 				/* This entry is expired, we will discard it. */
71 				break;
72 			cache_get(tmp);
73 			read_unlock(&detail->hash_lock);
74 			return tmp;
75 		}
76 	}
77 	read_unlock(&detail->hash_lock);
78 	/* Didn't find anything, insert an empty entry */
79 
80 	new = detail->alloc();
81 	if (!new)
82 		return NULL;
83 	/* must fully initialise 'new', else
84 	 * we might get lose if we need to
85 	 * cache_put it soon.
86 	 */
87 	cache_init(new, detail);
88 	detail->init(new, key);
89 
90 	write_lock(&detail->hash_lock);
91 
92 	/* check if entry appeared while we slept */
93 	hlist_for_each_entry(tmp, head, cache_list) {
94 		if (detail->match(tmp, key)) {
95 			if (cache_is_expired(detail, tmp)) {
96 				hlist_del_init(&tmp->cache_list);
97 				detail->entries --;
98 				freeme = tmp;
99 				break;
100 			}
101 			cache_get(tmp);
102 			write_unlock(&detail->hash_lock);
103 			cache_put(new, detail);
104 			return tmp;
105 		}
106 	}
107 
108 	hlist_add_head(&new->cache_list, head);
109 	detail->entries++;
110 	cache_get(new);
111 	write_unlock(&detail->hash_lock);
112 
113 	if (freeme)
114 		cache_put(freeme, detail);
115 	return new;
116 }
117 EXPORT_SYMBOL_GPL(sunrpc_cache_lookup);
118 
119 
120 static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch);
121 
cache_fresh_locked(struct cache_head * head,time_t expiry,struct cache_detail * detail)122 static void cache_fresh_locked(struct cache_head *head, time_t expiry,
123 			       struct cache_detail *detail)
124 {
125 	time_t now = seconds_since_boot();
126 	if (now <= detail->flush_time)
127 		/* ensure it isn't immediately treated as expired */
128 		now = detail->flush_time + 1;
129 	head->expiry_time = expiry;
130 	head->last_refresh = now;
131 	smp_wmb(); /* paired with smp_rmb() in cache_is_valid() */
132 	set_bit(CACHE_VALID, &head->flags);
133 }
134 
cache_fresh_unlocked(struct cache_head * head,struct cache_detail * detail)135 static void cache_fresh_unlocked(struct cache_head *head,
136 				 struct cache_detail *detail)
137 {
138 	if (test_and_clear_bit(CACHE_PENDING, &head->flags)) {
139 		cache_revisit_request(head);
140 		cache_dequeue(detail, head);
141 	}
142 }
143 
sunrpc_cache_update(struct cache_detail * detail,struct cache_head * new,struct cache_head * old,int hash)144 struct cache_head *sunrpc_cache_update(struct cache_detail *detail,
145 				       struct cache_head *new, struct cache_head *old, int hash)
146 {
147 	/* The 'old' entry is to be replaced by 'new'.
148 	 * If 'old' is not VALID, we update it directly,
149 	 * otherwise we need to replace it
150 	 */
151 	struct cache_head *tmp;
152 
153 	if (!test_bit(CACHE_VALID, &old->flags)) {
154 		write_lock(&detail->hash_lock);
155 		if (!test_bit(CACHE_VALID, &old->flags)) {
156 			if (test_bit(CACHE_NEGATIVE, &new->flags))
157 				set_bit(CACHE_NEGATIVE, &old->flags);
158 			else
159 				detail->update(old, new);
160 			cache_fresh_locked(old, new->expiry_time, detail);
161 			write_unlock(&detail->hash_lock);
162 			cache_fresh_unlocked(old, detail);
163 			return old;
164 		}
165 		write_unlock(&detail->hash_lock);
166 	}
167 	/* We need to insert a new entry */
168 	tmp = detail->alloc();
169 	if (!tmp) {
170 		cache_put(old, detail);
171 		return NULL;
172 	}
173 	cache_init(tmp, detail);
174 	detail->init(tmp, old);
175 
176 	write_lock(&detail->hash_lock);
177 	if (test_bit(CACHE_NEGATIVE, &new->flags))
178 		set_bit(CACHE_NEGATIVE, &tmp->flags);
179 	else
180 		detail->update(tmp, new);
181 	hlist_add_head(&tmp->cache_list, &detail->hash_table[hash]);
182 	detail->entries++;
183 	cache_get(tmp);
184 	cache_fresh_locked(tmp, new->expiry_time, detail);
185 	cache_fresh_locked(old, 0, detail);
186 	write_unlock(&detail->hash_lock);
187 	cache_fresh_unlocked(tmp, detail);
188 	cache_fresh_unlocked(old, detail);
189 	cache_put(old, detail);
190 	return tmp;
191 }
192 EXPORT_SYMBOL_GPL(sunrpc_cache_update);
193 
cache_make_upcall(struct cache_detail * cd,struct cache_head * h)194 static int cache_make_upcall(struct cache_detail *cd, struct cache_head *h)
195 {
196 	if (cd->cache_upcall)
197 		return cd->cache_upcall(cd, h);
198 	return sunrpc_cache_pipe_upcall(cd, h);
199 }
200 
cache_is_valid(struct cache_head * h)201 static inline int cache_is_valid(struct cache_head *h)
202 {
203 	if (!test_bit(CACHE_VALID, &h->flags))
204 		return -EAGAIN;
205 	else {
206 		/* entry is valid */
207 		if (test_bit(CACHE_NEGATIVE, &h->flags))
208 			return -ENOENT;
209 		else {
210 			/*
211 			 * In combination with write barrier in
212 			 * sunrpc_cache_update, ensures that anyone
213 			 * using the cache entry after this sees the
214 			 * updated contents:
215 			 */
216 			smp_rmb();
217 			return 0;
218 		}
219 	}
220 }
221 
try_to_negate_entry(struct cache_detail * detail,struct cache_head * h)222 static int try_to_negate_entry(struct cache_detail *detail, struct cache_head *h)
223 {
224 	int rv;
225 
226 	write_lock(&detail->hash_lock);
227 	rv = cache_is_valid(h);
228 	if (rv == -EAGAIN) {
229 		set_bit(CACHE_NEGATIVE, &h->flags);
230 		cache_fresh_locked(h, seconds_since_boot()+CACHE_NEW_EXPIRY,
231 				   detail);
232 		rv = -ENOENT;
233 	}
234 	write_unlock(&detail->hash_lock);
235 	cache_fresh_unlocked(h, detail);
236 	return rv;
237 }
238 
239 /*
240  * This is the generic cache management routine for all
241  * the authentication caches.
242  * It checks the currency of a cache item and will (later)
243  * initiate an upcall to fill it if needed.
244  *
245  *
246  * Returns 0 if the cache_head can be used, or cache_puts it and returns
247  * -EAGAIN if upcall is pending and request has been queued
248  * -ETIMEDOUT if upcall failed or request could not be queue or
249  *           upcall completed but item is still invalid (implying that
250  *           the cache item has been replaced with a newer one).
251  * -ENOENT if cache entry was negative
252  */
cache_check(struct cache_detail * detail,struct cache_head * h,struct cache_req * rqstp)253 int cache_check(struct cache_detail *detail,
254 		    struct cache_head *h, struct cache_req *rqstp)
255 {
256 	int rv;
257 	long refresh_age, age;
258 
259 	/* First decide return status as best we can */
260 	rv = cache_is_valid(h);
261 
262 	/* now see if we want to start an upcall */
263 	refresh_age = (h->expiry_time - h->last_refresh);
264 	age = seconds_since_boot() - h->last_refresh;
265 
266 	if (rqstp == NULL) {
267 		if (rv == -EAGAIN)
268 			rv = -ENOENT;
269 	} else if (rv == -EAGAIN ||
270 		   (h->expiry_time != 0 && age > refresh_age/2)) {
271 		dprintk("RPC:       Want update, refage=%ld, age=%ld\n",
272 				refresh_age, age);
273 		if (!test_and_set_bit(CACHE_PENDING, &h->flags)) {
274 			switch (cache_make_upcall(detail, h)) {
275 			case -EINVAL:
276 				rv = try_to_negate_entry(detail, h);
277 				break;
278 			case -EAGAIN:
279 				cache_fresh_unlocked(h, detail);
280 				break;
281 			}
282 		}
283 	}
284 
285 	if (rv == -EAGAIN) {
286 		if (!cache_defer_req(rqstp, h)) {
287 			/*
288 			 * Request was not deferred; handle it as best
289 			 * we can ourselves:
290 			 */
291 			rv = cache_is_valid(h);
292 			if (rv == -EAGAIN)
293 				rv = -ETIMEDOUT;
294 		}
295 	}
296 	if (rv)
297 		cache_put(h, detail);
298 	return rv;
299 }
300 EXPORT_SYMBOL_GPL(cache_check);
301 
302 /*
303  * caches need to be periodically cleaned.
304  * For this we maintain a list of cache_detail and
305  * a current pointer into that list and into the table
306  * for that entry.
307  *
308  * Each time cache_clean is called it finds the next non-empty entry
309  * in the current table and walks the list in that entry
310  * looking for entries that can be removed.
311  *
312  * An entry gets removed if:
313  * - The expiry is before current time
314  * - The last_refresh time is before the flush_time for that cache
315  *
316  * later we might drop old entries with non-NEVER expiry if that table
317  * is getting 'full' for some definition of 'full'
318  *
319  * The question of "how often to scan a table" is an interesting one
320  * and is answered in part by the use of the "nextcheck" field in the
321  * cache_detail.
322  * When a scan of a table begins, the nextcheck field is set to a time
323  * that is well into the future.
324  * While scanning, if an expiry time is found that is earlier than the
325  * current nextcheck time, nextcheck is set to that expiry time.
326  * If the flush_time is ever set to a time earlier than the nextcheck
327  * time, the nextcheck time is then set to that flush_time.
328  *
329  * A table is then only scanned if the current time is at least
330  * the nextcheck time.
331  *
332  */
333 
334 static LIST_HEAD(cache_list);
335 static DEFINE_SPINLOCK(cache_list_lock);
336 static struct cache_detail *current_detail;
337 static int current_index;
338 
339 static void do_cache_clean(struct work_struct *work);
340 static struct delayed_work cache_cleaner;
341 
sunrpc_init_cache_detail(struct cache_detail * cd)342 void sunrpc_init_cache_detail(struct cache_detail *cd)
343 {
344 	rwlock_init(&cd->hash_lock);
345 	INIT_LIST_HEAD(&cd->queue);
346 	spin_lock(&cache_list_lock);
347 	cd->nextcheck = 0;
348 	cd->entries = 0;
349 	atomic_set(&cd->readers, 0);
350 	cd->last_close = 0;
351 	cd->last_warn = -1;
352 	list_add(&cd->others, &cache_list);
353 	spin_unlock(&cache_list_lock);
354 
355 	/* start the cleaning process */
356 	queue_delayed_work(system_power_efficient_wq, &cache_cleaner, 0);
357 }
358 EXPORT_SYMBOL_GPL(sunrpc_init_cache_detail);
359 
sunrpc_destroy_cache_detail(struct cache_detail * cd)360 void sunrpc_destroy_cache_detail(struct cache_detail *cd)
361 {
362 	cache_purge(cd);
363 	spin_lock(&cache_list_lock);
364 	write_lock(&cd->hash_lock);
365 	if (cd->entries) {
366 		write_unlock(&cd->hash_lock);
367 		spin_unlock(&cache_list_lock);
368 		goto out;
369 	}
370 	if (current_detail == cd)
371 		current_detail = NULL;
372 	list_del_init(&cd->others);
373 	write_unlock(&cd->hash_lock);
374 	spin_unlock(&cache_list_lock);
375 	if (list_empty(&cache_list)) {
376 		/* module must be being unloaded so its safe to kill the worker */
377 		cancel_delayed_work_sync(&cache_cleaner);
378 	}
379 	return;
380 out:
381 	printk(KERN_ERR "RPC: failed to unregister %s cache\n", cd->name);
382 }
383 EXPORT_SYMBOL_GPL(sunrpc_destroy_cache_detail);
384 
385 /* clean cache tries to find something to clean
386  * and cleans it.
387  * It returns 1 if it cleaned something,
388  *            0 if it didn't find anything this time
389  *           -1 if it fell off the end of the list.
390  */
cache_clean(void)391 static int cache_clean(void)
392 {
393 	int rv = 0;
394 	struct list_head *next;
395 
396 	spin_lock(&cache_list_lock);
397 
398 	/* find a suitable table if we don't already have one */
399 	while (current_detail == NULL ||
400 	    current_index >= current_detail->hash_size) {
401 		if (current_detail)
402 			next = current_detail->others.next;
403 		else
404 			next = cache_list.next;
405 		if (next == &cache_list) {
406 			current_detail = NULL;
407 			spin_unlock(&cache_list_lock);
408 			return -1;
409 		}
410 		current_detail = list_entry(next, struct cache_detail, others);
411 		if (current_detail->nextcheck > seconds_since_boot())
412 			current_index = current_detail->hash_size;
413 		else {
414 			current_index = 0;
415 			current_detail->nextcheck = seconds_since_boot()+30*60;
416 		}
417 	}
418 
419 	/* find a non-empty bucket in the table */
420 	while (current_detail &&
421 	       current_index < current_detail->hash_size &&
422 	       hlist_empty(&current_detail->hash_table[current_index]))
423 		current_index++;
424 
425 	/* find a cleanable entry in the bucket and clean it, or set to next bucket */
426 
427 	if (current_detail && current_index < current_detail->hash_size) {
428 		struct cache_head *ch = NULL;
429 		struct cache_detail *d;
430 		struct hlist_head *head;
431 		struct hlist_node *tmp;
432 
433 		write_lock(&current_detail->hash_lock);
434 
435 		/* Ok, now to clean this strand */
436 
437 		head = &current_detail->hash_table[current_index];
438 		hlist_for_each_entry_safe(ch, tmp, head, cache_list) {
439 			if (current_detail->nextcheck > ch->expiry_time)
440 				current_detail->nextcheck = ch->expiry_time+1;
441 			if (!cache_is_expired(current_detail, ch))
442 				continue;
443 
444 			hlist_del_init(&ch->cache_list);
445 			current_detail->entries--;
446 			rv = 1;
447 			break;
448 		}
449 
450 		write_unlock(&current_detail->hash_lock);
451 		d = current_detail;
452 		if (!ch)
453 			current_index ++;
454 		spin_unlock(&cache_list_lock);
455 		if (ch) {
456 			set_bit(CACHE_CLEANED, &ch->flags);
457 			cache_fresh_unlocked(ch, d);
458 			cache_put(ch, d);
459 		}
460 	} else
461 		spin_unlock(&cache_list_lock);
462 
463 	return rv;
464 }
465 
466 /*
467  * We want to regularly clean the cache, so we need to schedule some work ...
468  */
do_cache_clean(struct work_struct * work)469 static void do_cache_clean(struct work_struct *work)
470 {
471 	int delay = 5;
472 	if (cache_clean() == -1)
473 		delay = round_jiffies_relative(30*HZ);
474 
475 	if (list_empty(&cache_list))
476 		delay = 0;
477 
478 	if (delay)
479 		queue_delayed_work(system_power_efficient_wq,
480 				   &cache_cleaner, delay);
481 }
482 
483 
484 /*
485  * Clean all caches promptly.  This just calls cache_clean
486  * repeatedly until we are sure that every cache has had a chance to
487  * be fully cleaned
488  */
cache_flush(void)489 void cache_flush(void)
490 {
491 	while (cache_clean() != -1)
492 		cond_resched();
493 	while (cache_clean() != -1)
494 		cond_resched();
495 }
496 EXPORT_SYMBOL_GPL(cache_flush);
497 
cache_purge(struct cache_detail * detail)498 void cache_purge(struct cache_detail *detail)
499 {
500 	time_t now = seconds_since_boot();
501 	if (detail->flush_time >= now)
502 		now = detail->flush_time + 1;
503 	/* 'now' is the maximum value any 'last_refresh' can have */
504 	detail->flush_time = now;
505 	detail->nextcheck = seconds_since_boot();
506 	cache_flush();
507 }
508 EXPORT_SYMBOL_GPL(cache_purge);
509 
510 
511 /*
512  * Deferral and Revisiting of Requests.
513  *
514  * If a cache lookup finds a pending entry, we
515  * need to defer the request and revisit it later.
516  * All deferred requests are stored in a hash table,
517  * indexed by "struct cache_head *".
518  * As it may be wasteful to store a whole request
519  * structure, we allow the request to provide a
520  * deferred form, which must contain a
521  * 'struct cache_deferred_req'
522  * This cache_deferred_req contains a method to allow
523  * it to be revisited when cache info is available
524  */
525 
526 #define	DFR_HASHSIZE	(PAGE_SIZE/sizeof(struct list_head))
527 #define	DFR_HASH(item)	((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE)
528 
529 #define	DFR_MAX	300	/* ??? */
530 
531 static DEFINE_SPINLOCK(cache_defer_lock);
532 static LIST_HEAD(cache_defer_list);
533 static struct hlist_head cache_defer_hash[DFR_HASHSIZE];
534 static int cache_defer_cnt;
535 
__unhash_deferred_req(struct cache_deferred_req * dreq)536 static void __unhash_deferred_req(struct cache_deferred_req *dreq)
537 {
538 	hlist_del_init(&dreq->hash);
539 	if (!list_empty(&dreq->recent)) {
540 		list_del_init(&dreq->recent);
541 		cache_defer_cnt--;
542 	}
543 }
544 
__hash_deferred_req(struct cache_deferred_req * dreq,struct cache_head * item)545 static void __hash_deferred_req(struct cache_deferred_req *dreq, struct cache_head *item)
546 {
547 	int hash = DFR_HASH(item);
548 
549 	INIT_LIST_HEAD(&dreq->recent);
550 	hlist_add_head(&dreq->hash, &cache_defer_hash[hash]);
551 }
552 
setup_deferral(struct cache_deferred_req * dreq,struct cache_head * item,int count_me)553 static void setup_deferral(struct cache_deferred_req *dreq,
554 			   struct cache_head *item,
555 			   int count_me)
556 {
557 
558 	dreq->item = item;
559 
560 	spin_lock(&cache_defer_lock);
561 
562 	__hash_deferred_req(dreq, item);
563 
564 	if (count_me) {
565 		cache_defer_cnt++;
566 		list_add(&dreq->recent, &cache_defer_list);
567 	}
568 
569 	spin_unlock(&cache_defer_lock);
570 
571 }
572 
573 struct thread_deferred_req {
574 	struct cache_deferred_req handle;
575 	struct completion completion;
576 };
577 
cache_restart_thread(struct cache_deferred_req * dreq,int too_many)578 static void cache_restart_thread(struct cache_deferred_req *dreq, int too_many)
579 {
580 	struct thread_deferred_req *dr =
581 		container_of(dreq, struct thread_deferred_req, handle);
582 	complete(&dr->completion);
583 }
584 
cache_wait_req(struct cache_req * req,struct cache_head * item)585 static void cache_wait_req(struct cache_req *req, struct cache_head *item)
586 {
587 	struct thread_deferred_req sleeper;
588 	struct cache_deferred_req *dreq = &sleeper.handle;
589 
590 	sleeper.completion = COMPLETION_INITIALIZER_ONSTACK(sleeper.completion);
591 	dreq->revisit = cache_restart_thread;
592 
593 	setup_deferral(dreq, item, 0);
594 
595 	if (!test_bit(CACHE_PENDING, &item->flags) ||
596 	    wait_for_completion_interruptible_timeout(
597 		    &sleeper.completion, req->thread_wait) <= 0) {
598 		/* The completion wasn't completed, so we need
599 		 * to clean up
600 		 */
601 		spin_lock(&cache_defer_lock);
602 		if (!hlist_unhashed(&sleeper.handle.hash)) {
603 			__unhash_deferred_req(&sleeper.handle);
604 			spin_unlock(&cache_defer_lock);
605 		} else {
606 			/* cache_revisit_request already removed
607 			 * this from the hash table, but hasn't
608 			 * called ->revisit yet.  It will very soon
609 			 * and we need to wait for it.
610 			 */
611 			spin_unlock(&cache_defer_lock);
612 			wait_for_completion(&sleeper.completion);
613 		}
614 	}
615 }
616 
cache_limit_defers(void)617 static void cache_limit_defers(void)
618 {
619 	/* Make sure we haven't exceed the limit of allowed deferred
620 	 * requests.
621 	 */
622 	struct cache_deferred_req *discard = NULL;
623 
624 	if (cache_defer_cnt <= DFR_MAX)
625 		return;
626 
627 	spin_lock(&cache_defer_lock);
628 
629 	/* Consider removing either the first or the last */
630 	if (cache_defer_cnt > DFR_MAX) {
631 		if (prandom_u32() & 1)
632 			discard = list_entry(cache_defer_list.next,
633 					     struct cache_deferred_req, recent);
634 		else
635 			discard = list_entry(cache_defer_list.prev,
636 					     struct cache_deferred_req, recent);
637 		__unhash_deferred_req(discard);
638 	}
639 	spin_unlock(&cache_defer_lock);
640 	if (discard)
641 		discard->revisit(discard, 1);
642 }
643 
644 /* Return true if and only if a deferred request is queued. */
cache_defer_req(struct cache_req * req,struct cache_head * item)645 static bool cache_defer_req(struct cache_req *req, struct cache_head *item)
646 {
647 	struct cache_deferred_req *dreq;
648 
649 	if (req->thread_wait) {
650 		cache_wait_req(req, item);
651 		if (!test_bit(CACHE_PENDING, &item->flags))
652 			return false;
653 	}
654 	dreq = req->defer(req);
655 	if (dreq == NULL)
656 		return false;
657 	setup_deferral(dreq, item, 1);
658 	if (!test_bit(CACHE_PENDING, &item->flags))
659 		/* Bit could have been cleared before we managed to
660 		 * set up the deferral, so need to revisit just in case
661 		 */
662 		cache_revisit_request(item);
663 
664 	cache_limit_defers();
665 	return true;
666 }
667 
cache_revisit_request(struct cache_head * item)668 static void cache_revisit_request(struct cache_head *item)
669 {
670 	struct cache_deferred_req *dreq;
671 	struct list_head pending;
672 	struct hlist_node *tmp;
673 	int hash = DFR_HASH(item);
674 
675 	INIT_LIST_HEAD(&pending);
676 	spin_lock(&cache_defer_lock);
677 
678 	hlist_for_each_entry_safe(dreq, tmp, &cache_defer_hash[hash], hash)
679 		if (dreq->item == item) {
680 			__unhash_deferred_req(dreq);
681 			list_add(&dreq->recent, &pending);
682 		}
683 
684 	spin_unlock(&cache_defer_lock);
685 
686 	while (!list_empty(&pending)) {
687 		dreq = list_entry(pending.next, struct cache_deferred_req, recent);
688 		list_del_init(&dreq->recent);
689 		dreq->revisit(dreq, 0);
690 	}
691 }
692 
cache_clean_deferred(void * owner)693 void cache_clean_deferred(void *owner)
694 {
695 	struct cache_deferred_req *dreq, *tmp;
696 	struct list_head pending;
697 
698 
699 	INIT_LIST_HEAD(&pending);
700 	spin_lock(&cache_defer_lock);
701 
702 	list_for_each_entry_safe(dreq, tmp, &cache_defer_list, recent) {
703 		if (dreq->owner == owner) {
704 			__unhash_deferred_req(dreq);
705 			list_add(&dreq->recent, &pending);
706 		}
707 	}
708 	spin_unlock(&cache_defer_lock);
709 
710 	while (!list_empty(&pending)) {
711 		dreq = list_entry(pending.next, struct cache_deferred_req, recent);
712 		list_del_init(&dreq->recent);
713 		dreq->revisit(dreq, 1);
714 	}
715 }
716 
717 /*
718  * communicate with user-space
719  *
720  * We have a magic /proc file - /proc/sunrpc/<cachename>/channel.
721  * On read, you get a full request, or block.
722  * On write, an update request is processed.
723  * Poll works if anything to read, and always allows write.
724  *
725  * Implemented by linked list of requests.  Each open file has
726  * a ->private that also exists in this list.  New requests are added
727  * to the end and may wakeup and preceding readers.
728  * New readers are added to the head.  If, on read, an item is found with
729  * CACHE_UPCALLING clear, we free it from the list.
730  *
731  */
732 
733 static DEFINE_SPINLOCK(queue_lock);
734 static DEFINE_MUTEX(queue_io_mutex);
735 
736 struct cache_queue {
737 	struct list_head	list;
738 	int			reader;	/* if 0, then request */
739 };
740 struct cache_request {
741 	struct cache_queue	q;
742 	struct cache_head	*item;
743 	char			* buf;
744 	int			len;
745 	int			readers;
746 };
747 struct cache_reader {
748 	struct cache_queue	q;
749 	int			offset;	/* if non-0, we have a refcnt on next request */
750 };
751 
cache_request(struct cache_detail * detail,struct cache_request * crq)752 static int cache_request(struct cache_detail *detail,
753 			       struct cache_request *crq)
754 {
755 	char *bp = crq->buf;
756 	int len = PAGE_SIZE;
757 
758 	detail->cache_request(detail, crq->item, &bp, &len);
759 	if (len < 0)
760 		return -EAGAIN;
761 	return PAGE_SIZE - len;
762 }
763 
cache_read(struct file * filp,char __user * buf,size_t count,loff_t * ppos,struct cache_detail * cd)764 static ssize_t cache_read(struct file *filp, char __user *buf, size_t count,
765 			  loff_t *ppos, struct cache_detail *cd)
766 {
767 	struct cache_reader *rp = filp->private_data;
768 	struct cache_request *rq;
769 	struct inode *inode = file_inode(filp);
770 	int err;
771 
772 	if (count == 0)
773 		return 0;
774 
775 	inode_lock(inode); /* protect against multiple concurrent
776 			      * readers on this file */
777  again:
778 	spin_lock(&queue_lock);
779 	/* need to find next request */
780 	while (rp->q.list.next != &cd->queue &&
781 	       list_entry(rp->q.list.next, struct cache_queue, list)
782 	       ->reader) {
783 		struct list_head *next = rp->q.list.next;
784 		list_move(&rp->q.list, next);
785 	}
786 	if (rp->q.list.next == &cd->queue) {
787 		spin_unlock(&queue_lock);
788 		inode_unlock(inode);
789 		WARN_ON_ONCE(rp->offset);
790 		return 0;
791 	}
792 	rq = container_of(rp->q.list.next, struct cache_request, q.list);
793 	WARN_ON_ONCE(rq->q.reader);
794 	if (rp->offset == 0)
795 		rq->readers++;
796 	spin_unlock(&queue_lock);
797 
798 	if (rq->len == 0) {
799 		err = cache_request(cd, rq);
800 		if (err < 0)
801 			goto out;
802 		rq->len = err;
803 	}
804 
805 	if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) {
806 		err = -EAGAIN;
807 		spin_lock(&queue_lock);
808 		list_move(&rp->q.list, &rq->q.list);
809 		spin_unlock(&queue_lock);
810 	} else {
811 		if (rp->offset + count > rq->len)
812 			count = rq->len - rp->offset;
813 		err = -EFAULT;
814 		if (copy_to_user(buf, rq->buf + rp->offset, count))
815 			goto out;
816 		rp->offset += count;
817 		if (rp->offset >= rq->len) {
818 			rp->offset = 0;
819 			spin_lock(&queue_lock);
820 			list_move(&rp->q.list, &rq->q.list);
821 			spin_unlock(&queue_lock);
822 		}
823 		err = 0;
824 	}
825  out:
826 	if (rp->offset == 0) {
827 		/* need to release rq */
828 		spin_lock(&queue_lock);
829 		rq->readers--;
830 		if (rq->readers == 0 &&
831 		    !test_bit(CACHE_PENDING, &rq->item->flags)) {
832 			list_del(&rq->q.list);
833 			spin_unlock(&queue_lock);
834 			cache_put(rq->item, cd);
835 			kfree(rq->buf);
836 			kfree(rq);
837 		} else
838 			spin_unlock(&queue_lock);
839 	}
840 	if (err == -EAGAIN)
841 		goto again;
842 	inode_unlock(inode);
843 	return err ? err :  count;
844 }
845 
cache_do_downcall(char * kaddr,const char __user * buf,size_t count,struct cache_detail * cd)846 static ssize_t cache_do_downcall(char *kaddr, const char __user *buf,
847 				 size_t count, struct cache_detail *cd)
848 {
849 	ssize_t ret;
850 
851 	if (count == 0)
852 		return -EINVAL;
853 	if (copy_from_user(kaddr, buf, count))
854 		return -EFAULT;
855 	kaddr[count] = '\0';
856 	ret = cd->cache_parse(cd, kaddr, count);
857 	if (!ret)
858 		ret = count;
859 	return ret;
860 }
861 
cache_slow_downcall(const char __user * buf,size_t count,struct cache_detail * cd)862 static ssize_t cache_slow_downcall(const char __user *buf,
863 				   size_t count, struct cache_detail *cd)
864 {
865 	static char write_buf[8192]; /* protected by queue_io_mutex */
866 	ssize_t ret = -EINVAL;
867 
868 	if (count >= sizeof(write_buf))
869 		goto out;
870 	mutex_lock(&queue_io_mutex);
871 	ret = cache_do_downcall(write_buf, buf, count, cd);
872 	mutex_unlock(&queue_io_mutex);
873 out:
874 	return ret;
875 }
876 
cache_downcall(struct address_space * mapping,const char __user * buf,size_t count,struct cache_detail * cd)877 static ssize_t cache_downcall(struct address_space *mapping,
878 			      const char __user *buf,
879 			      size_t count, struct cache_detail *cd)
880 {
881 	struct page *page;
882 	char *kaddr;
883 	ssize_t ret = -ENOMEM;
884 
885 	if (count >= PAGE_SIZE)
886 		goto out_slow;
887 
888 	page = find_or_create_page(mapping, 0, GFP_KERNEL);
889 	if (!page)
890 		goto out_slow;
891 
892 	kaddr = kmap(page);
893 	ret = cache_do_downcall(kaddr, buf, count, cd);
894 	kunmap(page);
895 	unlock_page(page);
896 	put_page(page);
897 	return ret;
898 out_slow:
899 	return cache_slow_downcall(buf, count, cd);
900 }
901 
cache_write(struct file * filp,const char __user * buf,size_t count,loff_t * ppos,struct cache_detail * cd)902 static ssize_t cache_write(struct file *filp, const char __user *buf,
903 			   size_t count, loff_t *ppos,
904 			   struct cache_detail *cd)
905 {
906 	struct address_space *mapping = filp->f_mapping;
907 	struct inode *inode = file_inode(filp);
908 	ssize_t ret = -EINVAL;
909 
910 	if (!cd->cache_parse)
911 		goto out;
912 
913 	inode_lock(inode);
914 	ret = cache_downcall(mapping, buf, count, cd);
915 	inode_unlock(inode);
916 out:
917 	return ret;
918 }
919 
920 static DECLARE_WAIT_QUEUE_HEAD(queue_wait);
921 
cache_poll(struct file * filp,poll_table * wait,struct cache_detail * cd)922 static unsigned int cache_poll(struct file *filp, poll_table *wait,
923 			       struct cache_detail *cd)
924 {
925 	unsigned int mask;
926 	struct cache_reader *rp = filp->private_data;
927 	struct cache_queue *cq;
928 
929 	poll_wait(filp, &queue_wait, wait);
930 
931 	/* alway allow write */
932 	mask = POLLOUT | POLLWRNORM;
933 
934 	if (!rp)
935 		return mask;
936 
937 	spin_lock(&queue_lock);
938 
939 	for (cq= &rp->q; &cq->list != &cd->queue;
940 	     cq = list_entry(cq->list.next, struct cache_queue, list))
941 		if (!cq->reader) {
942 			mask |= POLLIN | POLLRDNORM;
943 			break;
944 		}
945 	spin_unlock(&queue_lock);
946 	return mask;
947 }
948 
cache_ioctl(struct inode * ino,struct file * filp,unsigned int cmd,unsigned long arg,struct cache_detail * cd)949 static int cache_ioctl(struct inode *ino, struct file *filp,
950 		       unsigned int cmd, unsigned long arg,
951 		       struct cache_detail *cd)
952 {
953 	int len = 0;
954 	struct cache_reader *rp = filp->private_data;
955 	struct cache_queue *cq;
956 
957 	if (cmd != FIONREAD || !rp)
958 		return -EINVAL;
959 
960 	spin_lock(&queue_lock);
961 
962 	/* only find the length remaining in current request,
963 	 * or the length of the next request
964 	 */
965 	for (cq= &rp->q; &cq->list != &cd->queue;
966 	     cq = list_entry(cq->list.next, struct cache_queue, list))
967 		if (!cq->reader) {
968 			struct cache_request *cr =
969 				container_of(cq, struct cache_request, q);
970 			len = cr->len - rp->offset;
971 			break;
972 		}
973 	spin_unlock(&queue_lock);
974 
975 	return put_user(len, (int __user *)arg);
976 }
977 
cache_open(struct inode * inode,struct file * filp,struct cache_detail * cd)978 static int cache_open(struct inode *inode, struct file *filp,
979 		      struct cache_detail *cd)
980 {
981 	struct cache_reader *rp = NULL;
982 
983 	if (!cd || !try_module_get(cd->owner))
984 		return -EACCES;
985 	nonseekable_open(inode, filp);
986 	if (filp->f_mode & FMODE_READ) {
987 		rp = kmalloc(sizeof(*rp), GFP_KERNEL);
988 		if (!rp) {
989 			module_put(cd->owner);
990 			return -ENOMEM;
991 		}
992 		rp->offset = 0;
993 		rp->q.reader = 1;
994 		atomic_inc(&cd->readers);
995 		spin_lock(&queue_lock);
996 		list_add(&rp->q.list, &cd->queue);
997 		spin_unlock(&queue_lock);
998 	}
999 	filp->private_data = rp;
1000 	return 0;
1001 }
1002 
cache_release(struct inode * inode,struct file * filp,struct cache_detail * cd)1003 static int cache_release(struct inode *inode, struct file *filp,
1004 			 struct cache_detail *cd)
1005 {
1006 	struct cache_reader *rp = filp->private_data;
1007 
1008 	if (rp) {
1009 		spin_lock(&queue_lock);
1010 		if (rp->offset) {
1011 			struct cache_queue *cq;
1012 			for (cq= &rp->q; &cq->list != &cd->queue;
1013 			     cq = list_entry(cq->list.next, struct cache_queue, list))
1014 				if (!cq->reader) {
1015 					container_of(cq, struct cache_request, q)
1016 						->readers--;
1017 					break;
1018 				}
1019 			rp->offset = 0;
1020 		}
1021 		list_del(&rp->q.list);
1022 		spin_unlock(&queue_lock);
1023 
1024 		filp->private_data = NULL;
1025 		kfree(rp);
1026 
1027 		cd->last_close = seconds_since_boot();
1028 		atomic_dec(&cd->readers);
1029 	}
1030 	module_put(cd->owner);
1031 	return 0;
1032 }
1033 
1034 
1035 
cache_dequeue(struct cache_detail * detail,struct cache_head * ch)1036 static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch)
1037 {
1038 	struct cache_queue *cq, *tmp;
1039 	struct cache_request *cr;
1040 	struct list_head dequeued;
1041 
1042 	INIT_LIST_HEAD(&dequeued);
1043 	spin_lock(&queue_lock);
1044 	list_for_each_entry_safe(cq, tmp, &detail->queue, list)
1045 		if (!cq->reader) {
1046 			cr = container_of(cq, struct cache_request, q);
1047 			if (cr->item != ch)
1048 				continue;
1049 			if (test_bit(CACHE_PENDING, &ch->flags))
1050 				/* Lost a race and it is pending again */
1051 				break;
1052 			if (cr->readers != 0)
1053 				continue;
1054 			list_move(&cr->q.list, &dequeued);
1055 		}
1056 	spin_unlock(&queue_lock);
1057 	while (!list_empty(&dequeued)) {
1058 		cr = list_entry(dequeued.next, struct cache_request, q.list);
1059 		list_del(&cr->q.list);
1060 		cache_put(cr->item, detail);
1061 		kfree(cr->buf);
1062 		kfree(cr);
1063 	}
1064 }
1065 
1066 /*
1067  * Support routines for text-based upcalls.
1068  * Fields are separated by spaces.
1069  * Fields are either mangled to quote space tab newline slosh with slosh
1070  * or a hexified with a leading \x
1071  * Record is terminated with newline.
1072  *
1073  */
1074 
qword_add(char ** bpp,int * lp,char * str)1075 void qword_add(char **bpp, int *lp, char *str)
1076 {
1077 	char *bp = *bpp;
1078 	int len = *lp;
1079 	int ret;
1080 
1081 	if (len < 0) return;
1082 
1083 	ret = string_escape_str(str, bp, len, ESCAPE_OCTAL, "\\ \n\t");
1084 	if (ret >= len) {
1085 		bp += len;
1086 		len = -1;
1087 	} else {
1088 		bp += ret;
1089 		len -= ret;
1090 		*bp++ = ' ';
1091 		len--;
1092 	}
1093 	*bpp = bp;
1094 	*lp = len;
1095 }
1096 EXPORT_SYMBOL_GPL(qword_add);
1097 
qword_addhex(char ** bpp,int * lp,char * buf,int blen)1098 void qword_addhex(char **bpp, int *lp, char *buf, int blen)
1099 {
1100 	char *bp = *bpp;
1101 	int len = *lp;
1102 
1103 	if (len < 0) return;
1104 
1105 	if (len > 2) {
1106 		*bp++ = '\\';
1107 		*bp++ = 'x';
1108 		len -= 2;
1109 		while (blen && len >= 2) {
1110 			bp = hex_byte_pack(bp, *buf++);
1111 			len -= 2;
1112 			blen--;
1113 		}
1114 	}
1115 	if (blen || len<1) len = -1;
1116 	else {
1117 		*bp++ = ' ';
1118 		len--;
1119 	}
1120 	*bpp = bp;
1121 	*lp = len;
1122 }
1123 EXPORT_SYMBOL_GPL(qword_addhex);
1124 
warn_no_listener(struct cache_detail * detail)1125 static void warn_no_listener(struct cache_detail *detail)
1126 {
1127 	if (detail->last_warn != detail->last_close) {
1128 		detail->last_warn = detail->last_close;
1129 		if (detail->warn_no_listener)
1130 			detail->warn_no_listener(detail, detail->last_close != 0);
1131 	}
1132 }
1133 
cache_listeners_exist(struct cache_detail * detail)1134 static bool cache_listeners_exist(struct cache_detail *detail)
1135 {
1136 	if (atomic_read(&detail->readers))
1137 		return true;
1138 	if (detail->last_close == 0)
1139 		/* This cache was never opened */
1140 		return false;
1141 	if (detail->last_close < seconds_since_boot() - 30)
1142 		/*
1143 		 * We allow for the possibility that someone might
1144 		 * restart a userspace daemon without restarting the
1145 		 * server; but after 30 seconds, we give up.
1146 		 */
1147 		 return false;
1148 	return true;
1149 }
1150 
1151 /*
1152  * register an upcall request to user-space and queue it up for read() by the
1153  * upcall daemon.
1154  *
1155  * Each request is at most one page long.
1156  */
sunrpc_cache_pipe_upcall(struct cache_detail * detail,struct cache_head * h)1157 int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h)
1158 {
1159 
1160 	char *buf;
1161 	struct cache_request *crq;
1162 	int ret = 0;
1163 
1164 	if (!detail->cache_request)
1165 		return -EINVAL;
1166 
1167 	if (!cache_listeners_exist(detail)) {
1168 		warn_no_listener(detail);
1169 		return -EINVAL;
1170 	}
1171 	if (test_bit(CACHE_CLEANED, &h->flags))
1172 		/* Too late to make an upcall */
1173 		return -EAGAIN;
1174 
1175 	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
1176 	if (!buf)
1177 		return -EAGAIN;
1178 
1179 	crq = kmalloc(sizeof (*crq), GFP_KERNEL);
1180 	if (!crq) {
1181 		kfree(buf);
1182 		return -EAGAIN;
1183 	}
1184 
1185 	crq->q.reader = 0;
1186 	crq->buf = buf;
1187 	crq->len = 0;
1188 	crq->readers = 0;
1189 	spin_lock(&queue_lock);
1190 	if (test_bit(CACHE_PENDING, &h->flags)) {
1191 		crq->item = cache_get(h);
1192 		list_add_tail(&crq->q.list, &detail->queue);
1193 	} else
1194 		/* Lost a race, no longer PENDING, so don't enqueue */
1195 		ret = -EAGAIN;
1196 	spin_unlock(&queue_lock);
1197 	wake_up(&queue_wait);
1198 	if (ret == -EAGAIN) {
1199 		kfree(buf);
1200 		kfree(crq);
1201 	}
1202 	return ret;
1203 }
1204 EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall);
1205 
1206 /*
1207  * parse a message from user-space and pass it
1208  * to an appropriate cache
1209  * Messages are, like requests, separated into fields by
1210  * spaces and dequotes as \xHEXSTRING or embedded \nnn octal
1211  *
1212  * Message is
1213  *   reply cachename expiry key ... content....
1214  *
1215  * key and content are both parsed by cache
1216  */
1217 
qword_get(char ** bpp,char * dest,int bufsize)1218 int qword_get(char **bpp, char *dest, int bufsize)
1219 {
1220 	/* return bytes copied, or -1 on error */
1221 	char *bp = *bpp;
1222 	int len = 0;
1223 
1224 	while (*bp == ' ') bp++;
1225 
1226 	if (bp[0] == '\\' && bp[1] == 'x') {
1227 		/* HEX STRING */
1228 		bp += 2;
1229 		while (len < bufsize - 1) {
1230 			int h, l;
1231 
1232 			h = hex_to_bin(bp[0]);
1233 			if (h < 0)
1234 				break;
1235 
1236 			l = hex_to_bin(bp[1]);
1237 			if (l < 0)
1238 				break;
1239 
1240 			*dest++ = (h << 4) | l;
1241 			bp += 2;
1242 			len++;
1243 		}
1244 	} else {
1245 		/* text with \nnn octal quoting */
1246 		while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) {
1247 			if (*bp == '\\' &&
1248 			    isodigit(bp[1]) && (bp[1] <= '3') &&
1249 			    isodigit(bp[2]) &&
1250 			    isodigit(bp[3])) {
1251 				int byte = (*++bp -'0');
1252 				bp++;
1253 				byte = (byte << 3) | (*bp++ - '0');
1254 				byte = (byte << 3) | (*bp++ - '0');
1255 				*dest++ = byte;
1256 				len++;
1257 			} else {
1258 				*dest++ = *bp++;
1259 				len++;
1260 			}
1261 		}
1262 	}
1263 
1264 	if (*bp != ' ' && *bp != '\n' && *bp != '\0')
1265 		return -1;
1266 	while (*bp == ' ') bp++;
1267 	*bpp = bp;
1268 	*dest = '\0';
1269 	return len;
1270 }
1271 EXPORT_SYMBOL_GPL(qword_get);
1272 
1273 
1274 /*
1275  * support /proc/sunrpc/cache/$CACHENAME/content
1276  * as a seqfile.
1277  * We call ->cache_show passing NULL for the item to
1278  * get a header, then pass each real item in the cache
1279  */
1280 
cache_seq_start(struct seq_file * m,loff_t * pos)1281 void *cache_seq_start(struct seq_file *m, loff_t *pos)
1282 	__acquires(cd->hash_lock)
1283 {
1284 	loff_t n = *pos;
1285 	unsigned int hash, entry;
1286 	struct cache_head *ch;
1287 	struct cache_detail *cd = m->private;
1288 
1289 	read_lock(&cd->hash_lock);
1290 	if (!n--)
1291 		return SEQ_START_TOKEN;
1292 	hash = n >> 32;
1293 	entry = n & ((1LL<<32) - 1);
1294 
1295 	hlist_for_each_entry(ch, &cd->hash_table[hash], cache_list)
1296 		if (!entry--)
1297 			return ch;
1298 	n &= ~((1LL<<32) - 1);
1299 	do {
1300 		hash++;
1301 		n += 1LL<<32;
1302 	} while(hash < cd->hash_size &&
1303 		hlist_empty(&cd->hash_table[hash]));
1304 	if (hash >= cd->hash_size)
1305 		return NULL;
1306 	*pos = n+1;
1307 	return hlist_entry_safe(cd->hash_table[hash].first,
1308 				struct cache_head, cache_list);
1309 }
1310 EXPORT_SYMBOL_GPL(cache_seq_start);
1311 
cache_seq_next(struct seq_file * m,void * p,loff_t * pos)1312 void *cache_seq_next(struct seq_file *m, void *p, loff_t *pos)
1313 {
1314 	struct cache_head *ch = p;
1315 	int hash = (*pos >> 32);
1316 	struct cache_detail *cd = m->private;
1317 
1318 	if (p == SEQ_START_TOKEN)
1319 		hash = 0;
1320 	else if (ch->cache_list.next == NULL) {
1321 		hash++;
1322 		*pos += 1LL<<32;
1323 	} else {
1324 		++*pos;
1325 		return hlist_entry_safe(ch->cache_list.next,
1326 					struct cache_head, cache_list);
1327 	}
1328 	*pos &= ~((1LL<<32) - 1);
1329 	while (hash < cd->hash_size &&
1330 	       hlist_empty(&cd->hash_table[hash])) {
1331 		hash++;
1332 		*pos += 1LL<<32;
1333 	}
1334 	if (hash >= cd->hash_size)
1335 		return NULL;
1336 	++*pos;
1337 	return hlist_entry_safe(cd->hash_table[hash].first,
1338 				struct cache_head, cache_list);
1339 }
1340 EXPORT_SYMBOL_GPL(cache_seq_next);
1341 
cache_seq_stop(struct seq_file * m,void * p)1342 void cache_seq_stop(struct seq_file *m, void *p)
1343 	__releases(cd->hash_lock)
1344 {
1345 	struct cache_detail *cd = m->private;
1346 	read_unlock(&cd->hash_lock);
1347 }
1348 EXPORT_SYMBOL_GPL(cache_seq_stop);
1349 
c_show(struct seq_file * m,void * p)1350 static int c_show(struct seq_file *m, void *p)
1351 {
1352 	struct cache_head *cp = p;
1353 	struct cache_detail *cd = m->private;
1354 
1355 	if (p == SEQ_START_TOKEN)
1356 		return cd->cache_show(m, cd, NULL);
1357 
1358 	ifdebug(CACHE)
1359 		seq_printf(m, "# expiry=%ld refcnt=%d flags=%lx\n",
1360 			   convert_to_wallclock(cp->expiry_time),
1361 			   atomic_read(&cp->ref.refcount), cp->flags);
1362 	cache_get(cp);
1363 	if (cache_check(cd, cp, NULL))
1364 		/* cache_check does a cache_put on failure */
1365 		seq_printf(m, "# ");
1366 	else {
1367 		if (cache_is_expired(cd, cp))
1368 			seq_printf(m, "# ");
1369 		cache_put(cp, cd);
1370 	}
1371 
1372 	return cd->cache_show(m, cd, cp);
1373 }
1374 
1375 static const struct seq_operations cache_content_op = {
1376 	.start	= cache_seq_start,
1377 	.next	= cache_seq_next,
1378 	.stop	= cache_seq_stop,
1379 	.show	= c_show,
1380 };
1381 
content_open(struct inode * inode,struct file * file,struct cache_detail * cd)1382 static int content_open(struct inode *inode, struct file *file,
1383 			struct cache_detail *cd)
1384 {
1385 	struct seq_file *seq;
1386 	int err;
1387 
1388 	if (!cd || !try_module_get(cd->owner))
1389 		return -EACCES;
1390 
1391 	err = seq_open(file, &cache_content_op);
1392 	if (err) {
1393 		module_put(cd->owner);
1394 		return err;
1395 	}
1396 
1397 	seq = file->private_data;
1398 	seq->private = cd;
1399 	return 0;
1400 }
1401 
content_release(struct inode * inode,struct file * file,struct cache_detail * cd)1402 static int content_release(struct inode *inode, struct file *file,
1403 		struct cache_detail *cd)
1404 {
1405 	int ret = seq_release(inode, file);
1406 	module_put(cd->owner);
1407 	return ret;
1408 }
1409 
open_flush(struct inode * inode,struct file * file,struct cache_detail * cd)1410 static int open_flush(struct inode *inode, struct file *file,
1411 			struct cache_detail *cd)
1412 {
1413 	if (!cd || !try_module_get(cd->owner))
1414 		return -EACCES;
1415 	return nonseekable_open(inode, file);
1416 }
1417 
release_flush(struct inode * inode,struct file * file,struct cache_detail * cd)1418 static int release_flush(struct inode *inode, struct file *file,
1419 			struct cache_detail *cd)
1420 {
1421 	module_put(cd->owner);
1422 	return 0;
1423 }
1424 
read_flush(struct file * file,char __user * buf,size_t count,loff_t * ppos,struct cache_detail * cd)1425 static ssize_t read_flush(struct file *file, char __user *buf,
1426 			  size_t count, loff_t *ppos,
1427 			  struct cache_detail *cd)
1428 {
1429 	char tbuf[22];
1430 	unsigned long p = *ppos;
1431 	size_t len;
1432 
1433 	snprintf(tbuf, sizeof(tbuf), "%lu\n", convert_to_wallclock(cd->flush_time));
1434 	len = strlen(tbuf);
1435 	if (p >= len)
1436 		return 0;
1437 	len -= p;
1438 	if (len > count)
1439 		len = count;
1440 	if (copy_to_user(buf, (void*)(tbuf+p), len))
1441 		return -EFAULT;
1442 	*ppos += len;
1443 	return len;
1444 }
1445 
write_flush(struct file * file,const char __user * buf,size_t count,loff_t * ppos,struct cache_detail * cd)1446 static ssize_t write_flush(struct file *file, const char __user *buf,
1447 			   size_t count, loff_t *ppos,
1448 			   struct cache_detail *cd)
1449 {
1450 	char tbuf[20];
1451 	char *bp, *ep;
1452 	time_t then, now;
1453 
1454 	if (*ppos || count > sizeof(tbuf)-1)
1455 		return -EINVAL;
1456 	if (copy_from_user(tbuf, buf, count))
1457 		return -EFAULT;
1458 	tbuf[count] = 0;
1459 	simple_strtoul(tbuf, &ep, 0);
1460 	if (*ep && *ep != '\n')
1461 		return -EINVAL;
1462 
1463 	bp = tbuf;
1464 	then = get_expiry(&bp);
1465 	now = seconds_since_boot();
1466 	cd->nextcheck = now;
1467 	/* Can only set flush_time to 1 second beyond "now", or
1468 	 * possibly 1 second beyond flushtime.  This is because
1469 	 * flush_time never goes backwards so it mustn't get too far
1470 	 * ahead of time.
1471 	 */
1472 	if (then >= now) {
1473 		/* Want to flush everything, so behave like cache_purge() */
1474 		if (cd->flush_time >= now)
1475 			now = cd->flush_time + 1;
1476 		then = now;
1477 	}
1478 
1479 	cd->flush_time = then;
1480 	cache_flush();
1481 
1482 	*ppos += count;
1483 	return count;
1484 }
1485 
cache_read_procfs(struct file * filp,char __user * buf,size_t count,loff_t * ppos)1486 static ssize_t cache_read_procfs(struct file *filp, char __user *buf,
1487 				 size_t count, loff_t *ppos)
1488 {
1489 	struct cache_detail *cd = PDE_DATA(file_inode(filp));
1490 
1491 	return cache_read(filp, buf, count, ppos, cd);
1492 }
1493 
cache_write_procfs(struct file * filp,const char __user * buf,size_t count,loff_t * ppos)1494 static ssize_t cache_write_procfs(struct file *filp, const char __user *buf,
1495 				  size_t count, loff_t *ppos)
1496 {
1497 	struct cache_detail *cd = PDE_DATA(file_inode(filp));
1498 
1499 	return cache_write(filp, buf, count, ppos, cd);
1500 }
1501 
cache_poll_procfs(struct file * filp,poll_table * wait)1502 static unsigned int cache_poll_procfs(struct file *filp, poll_table *wait)
1503 {
1504 	struct cache_detail *cd = PDE_DATA(file_inode(filp));
1505 
1506 	return cache_poll(filp, wait, cd);
1507 }
1508 
cache_ioctl_procfs(struct file * filp,unsigned int cmd,unsigned long arg)1509 static long cache_ioctl_procfs(struct file *filp,
1510 			       unsigned int cmd, unsigned long arg)
1511 {
1512 	struct inode *inode = file_inode(filp);
1513 	struct cache_detail *cd = PDE_DATA(inode);
1514 
1515 	return cache_ioctl(inode, filp, cmd, arg, cd);
1516 }
1517 
cache_open_procfs(struct inode * inode,struct file * filp)1518 static int cache_open_procfs(struct inode *inode, struct file *filp)
1519 {
1520 	struct cache_detail *cd = PDE_DATA(inode);
1521 
1522 	return cache_open(inode, filp, cd);
1523 }
1524 
cache_release_procfs(struct inode * inode,struct file * filp)1525 static int cache_release_procfs(struct inode *inode, struct file *filp)
1526 {
1527 	struct cache_detail *cd = PDE_DATA(inode);
1528 
1529 	return cache_release(inode, filp, cd);
1530 }
1531 
1532 static const struct file_operations cache_file_operations_procfs = {
1533 	.owner		= THIS_MODULE,
1534 	.llseek		= no_llseek,
1535 	.read		= cache_read_procfs,
1536 	.write		= cache_write_procfs,
1537 	.poll		= cache_poll_procfs,
1538 	.unlocked_ioctl	= cache_ioctl_procfs, /* for FIONREAD */
1539 	.open		= cache_open_procfs,
1540 	.release	= cache_release_procfs,
1541 };
1542 
content_open_procfs(struct inode * inode,struct file * filp)1543 static int content_open_procfs(struct inode *inode, struct file *filp)
1544 {
1545 	struct cache_detail *cd = PDE_DATA(inode);
1546 
1547 	return content_open(inode, filp, cd);
1548 }
1549 
content_release_procfs(struct inode * inode,struct file * filp)1550 static int content_release_procfs(struct inode *inode, struct file *filp)
1551 {
1552 	struct cache_detail *cd = PDE_DATA(inode);
1553 
1554 	return content_release(inode, filp, cd);
1555 }
1556 
1557 static const struct file_operations content_file_operations_procfs = {
1558 	.open		= content_open_procfs,
1559 	.read		= seq_read,
1560 	.llseek		= seq_lseek,
1561 	.release	= content_release_procfs,
1562 };
1563 
open_flush_procfs(struct inode * inode,struct file * filp)1564 static int open_flush_procfs(struct inode *inode, struct file *filp)
1565 {
1566 	struct cache_detail *cd = PDE_DATA(inode);
1567 
1568 	return open_flush(inode, filp, cd);
1569 }
1570 
release_flush_procfs(struct inode * inode,struct file * filp)1571 static int release_flush_procfs(struct inode *inode, struct file *filp)
1572 {
1573 	struct cache_detail *cd = PDE_DATA(inode);
1574 
1575 	return release_flush(inode, filp, cd);
1576 }
1577 
read_flush_procfs(struct file * filp,char __user * buf,size_t count,loff_t * ppos)1578 static ssize_t read_flush_procfs(struct file *filp, char __user *buf,
1579 			    size_t count, loff_t *ppos)
1580 {
1581 	struct cache_detail *cd = PDE_DATA(file_inode(filp));
1582 
1583 	return read_flush(filp, buf, count, ppos, cd);
1584 }
1585 
write_flush_procfs(struct file * filp,const char __user * buf,size_t count,loff_t * ppos)1586 static ssize_t write_flush_procfs(struct file *filp,
1587 				  const char __user *buf,
1588 				  size_t count, loff_t *ppos)
1589 {
1590 	struct cache_detail *cd = PDE_DATA(file_inode(filp));
1591 
1592 	return write_flush(filp, buf, count, ppos, cd);
1593 }
1594 
1595 static const struct file_operations cache_flush_operations_procfs = {
1596 	.open		= open_flush_procfs,
1597 	.read		= read_flush_procfs,
1598 	.write		= write_flush_procfs,
1599 	.release	= release_flush_procfs,
1600 	.llseek		= no_llseek,
1601 };
1602 
remove_cache_proc_entries(struct cache_detail * cd,struct net * net)1603 static void remove_cache_proc_entries(struct cache_detail *cd, struct net *net)
1604 {
1605 	struct sunrpc_net *sn;
1606 
1607 	if (cd->u.procfs.proc_ent == NULL)
1608 		return;
1609 	if (cd->u.procfs.flush_ent)
1610 		remove_proc_entry("flush", cd->u.procfs.proc_ent);
1611 	if (cd->u.procfs.channel_ent)
1612 		remove_proc_entry("channel", cd->u.procfs.proc_ent);
1613 	if (cd->u.procfs.content_ent)
1614 		remove_proc_entry("content", cd->u.procfs.proc_ent);
1615 	cd->u.procfs.proc_ent = NULL;
1616 	sn = net_generic(net, sunrpc_net_id);
1617 	remove_proc_entry(cd->name, sn->proc_net_rpc);
1618 }
1619 
1620 #ifdef CONFIG_PROC_FS
create_cache_proc_entries(struct cache_detail * cd,struct net * net)1621 static int create_cache_proc_entries(struct cache_detail *cd, struct net *net)
1622 {
1623 	struct proc_dir_entry *p;
1624 	struct sunrpc_net *sn;
1625 
1626 	sn = net_generic(net, sunrpc_net_id);
1627 	cd->u.procfs.proc_ent = proc_mkdir(cd->name, sn->proc_net_rpc);
1628 	if (cd->u.procfs.proc_ent == NULL)
1629 		goto out_nomem;
1630 	cd->u.procfs.channel_ent = NULL;
1631 	cd->u.procfs.content_ent = NULL;
1632 
1633 	p = proc_create_data("flush", S_IFREG|S_IRUSR|S_IWUSR,
1634 			     cd->u.procfs.proc_ent,
1635 			     &cache_flush_operations_procfs, cd);
1636 	cd->u.procfs.flush_ent = p;
1637 	if (p == NULL)
1638 		goto out_nomem;
1639 
1640 	if (cd->cache_request || cd->cache_parse) {
1641 		p = proc_create_data("channel", S_IFREG|S_IRUSR|S_IWUSR,
1642 				     cd->u.procfs.proc_ent,
1643 				     &cache_file_operations_procfs, cd);
1644 		cd->u.procfs.channel_ent = p;
1645 		if (p == NULL)
1646 			goto out_nomem;
1647 	}
1648 	if (cd->cache_show) {
1649 		p = proc_create_data("content", S_IFREG|S_IRUSR,
1650 				cd->u.procfs.proc_ent,
1651 				&content_file_operations_procfs, cd);
1652 		cd->u.procfs.content_ent = p;
1653 		if (p == NULL)
1654 			goto out_nomem;
1655 	}
1656 	return 0;
1657 out_nomem:
1658 	remove_cache_proc_entries(cd, net);
1659 	return -ENOMEM;
1660 }
1661 #else /* CONFIG_PROC_FS */
create_cache_proc_entries(struct cache_detail * cd,struct net * net)1662 static int create_cache_proc_entries(struct cache_detail *cd, struct net *net)
1663 {
1664 	return 0;
1665 }
1666 #endif
1667 
cache_initialize(void)1668 void __init cache_initialize(void)
1669 {
1670 	INIT_DEFERRABLE_WORK(&cache_cleaner, do_cache_clean);
1671 }
1672 
cache_register_net(struct cache_detail * cd,struct net * net)1673 int cache_register_net(struct cache_detail *cd, struct net *net)
1674 {
1675 	int ret;
1676 
1677 	sunrpc_init_cache_detail(cd);
1678 	ret = create_cache_proc_entries(cd, net);
1679 	if (ret)
1680 		sunrpc_destroy_cache_detail(cd);
1681 	return ret;
1682 }
1683 EXPORT_SYMBOL_GPL(cache_register_net);
1684 
cache_unregister_net(struct cache_detail * cd,struct net * net)1685 void cache_unregister_net(struct cache_detail *cd, struct net *net)
1686 {
1687 	remove_cache_proc_entries(cd, net);
1688 	sunrpc_destroy_cache_detail(cd);
1689 }
1690 EXPORT_SYMBOL_GPL(cache_unregister_net);
1691 
cache_create_net(struct cache_detail * tmpl,struct net * net)1692 struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net)
1693 {
1694 	struct cache_detail *cd;
1695 	int i;
1696 
1697 	cd = kmemdup(tmpl, sizeof(struct cache_detail), GFP_KERNEL);
1698 	if (cd == NULL)
1699 		return ERR_PTR(-ENOMEM);
1700 
1701 	cd->hash_table = kzalloc(cd->hash_size * sizeof(struct hlist_head),
1702 				 GFP_KERNEL);
1703 	if (cd->hash_table == NULL) {
1704 		kfree(cd);
1705 		return ERR_PTR(-ENOMEM);
1706 	}
1707 
1708 	for (i = 0; i < cd->hash_size; i++)
1709 		INIT_HLIST_HEAD(&cd->hash_table[i]);
1710 	cd->net = net;
1711 	return cd;
1712 }
1713 EXPORT_SYMBOL_GPL(cache_create_net);
1714 
cache_destroy_net(struct cache_detail * cd,struct net * net)1715 void cache_destroy_net(struct cache_detail *cd, struct net *net)
1716 {
1717 	kfree(cd->hash_table);
1718 	kfree(cd);
1719 }
1720 EXPORT_SYMBOL_GPL(cache_destroy_net);
1721 
cache_read_pipefs(struct file * filp,char __user * buf,size_t count,loff_t * ppos)1722 static ssize_t cache_read_pipefs(struct file *filp, char __user *buf,
1723 				 size_t count, loff_t *ppos)
1724 {
1725 	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1726 
1727 	return cache_read(filp, buf, count, ppos, cd);
1728 }
1729 
cache_write_pipefs(struct file * filp,const char __user * buf,size_t count,loff_t * ppos)1730 static ssize_t cache_write_pipefs(struct file *filp, const char __user *buf,
1731 				  size_t count, loff_t *ppos)
1732 {
1733 	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1734 
1735 	return cache_write(filp, buf, count, ppos, cd);
1736 }
1737 
cache_poll_pipefs(struct file * filp,poll_table * wait)1738 static unsigned int cache_poll_pipefs(struct file *filp, poll_table *wait)
1739 {
1740 	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1741 
1742 	return cache_poll(filp, wait, cd);
1743 }
1744 
cache_ioctl_pipefs(struct file * filp,unsigned int cmd,unsigned long arg)1745 static long cache_ioctl_pipefs(struct file *filp,
1746 			      unsigned int cmd, unsigned long arg)
1747 {
1748 	struct inode *inode = file_inode(filp);
1749 	struct cache_detail *cd = RPC_I(inode)->private;
1750 
1751 	return cache_ioctl(inode, filp, cmd, arg, cd);
1752 }
1753 
cache_open_pipefs(struct inode * inode,struct file * filp)1754 static int cache_open_pipefs(struct inode *inode, struct file *filp)
1755 {
1756 	struct cache_detail *cd = RPC_I(inode)->private;
1757 
1758 	return cache_open(inode, filp, cd);
1759 }
1760 
cache_release_pipefs(struct inode * inode,struct file * filp)1761 static int cache_release_pipefs(struct inode *inode, struct file *filp)
1762 {
1763 	struct cache_detail *cd = RPC_I(inode)->private;
1764 
1765 	return cache_release(inode, filp, cd);
1766 }
1767 
1768 const struct file_operations cache_file_operations_pipefs = {
1769 	.owner		= THIS_MODULE,
1770 	.llseek		= no_llseek,
1771 	.read		= cache_read_pipefs,
1772 	.write		= cache_write_pipefs,
1773 	.poll		= cache_poll_pipefs,
1774 	.unlocked_ioctl	= cache_ioctl_pipefs, /* for FIONREAD */
1775 	.open		= cache_open_pipefs,
1776 	.release	= cache_release_pipefs,
1777 };
1778 
content_open_pipefs(struct inode * inode,struct file * filp)1779 static int content_open_pipefs(struct inode *inode, struct file *filp)
1780 {
1781 	struct cache_detail *cd = RPC_I(inode)->private;
1782 
1783 	return content_open(inode, filp, cd);
1784 }
1785 
content_release_pipefs(struct inode * inode,struct file * filp)1786 static int content_release_pipefs(struct inode *inode, struct file *filp)
1787 {
1788 	struct cache_detail *cd = RPC_I(inode)->private;
1789 
1790 	return content_release(inode, filp, cd);
1791 }
1792 
1793 const struct file_operations content_file_operations_pipefs = {
1794 	.open		= content_open_pipefs,
1795 	.read		= seq_read,
1796 	.llseek		= seq_lseek,
1797 	.release	= content_release_pipefs,
1798 };
1799 
open_flush_pipefs(struct inode * inode,struct file * filp)1800 static int open_flush_pipefs(struct inode *inode, struct file *filp)
1801 {
1802 	struct cache_detail *cd = RPC_I(inode)->private;
1803 
1804 	return open_flush(inode, filp, cd);
1805 }
1806 
release_flush_pipefs(struct inode * inode,struct file * filp)1807 static int release_flush_pipefs(struct inode *inode, struct file *filp)
1808 {
1809 	struct cache_detail *cd = RPC_I(inode)->private;
1810 
1811 	return release_flush(inode, filp, cd);
1812 }
1813 
read_flush_pipefs(struct file * filp,char __user * buf,size_t count,loff_t * ppos)1814 static ssize_t read_flush_pipefs(struct file *filp, char __user *buf,
1815 			    size_t count, loff_t *ppos)
1816 {
1817 	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1818 
1819 	return read_flush(filp, buf, count, ppos, cd);
1820 }
1821 
write_flush_pipefs(struct file * filp,const char __user * buf,size_t count,loff_t * ppos)1822 static ssize_t write_flush_pipefs(struct file *filp,
1823 				  const char __user *buf,
1824 				  size_t count, loff_t *ppos)
1825 {
1826 	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1827 
1828 	return write_flush(filp, buf, count, ppos, cd);
1829 }
1830 
1831 const struct file_operations cache_flush_operations_pipefs = {
1832 	.open		= open_flush_pipefs,
1833 	.read		= read_flush_pipefs,
1834 	.write		= write_flush_pipefs,
1835 	.release	= release_flush_pipefs,
1836 	.llseek		= no_llseek,
1837 };
1838 
sunrpc_cache_register_pipefs(struct dentry * parent,const char * name,umode_t umode,struct cache_detail * cd)1839 int sunrpc_cache_register_pipefs(struct dentry *parent,
1840 				 const char *name, umode_t umode,
1841 				 struct cache_detail *cd)
1842 {
1843 	struct dentry *dir = rpc_create_cache_dir(parent, name, umode, cd);
1844 	if (IS_ERR(dir))
1845 		return PTR_ERR(dir);
1846 	cd->u.pipefs.dir = dir;
1847 	return 0;
1848 }
1849 EXPORT_SYMBOL_GPL(sunrpc_cache_register_pipefs);
1850 
sunrpc_cache_unregister_pipefs(struct cache_detail * cd)1851 void sunrpc_cache_unregister_pipefs(struct cache_detail *cd)
1852 {
1853 	rpc_remove_cache_dir(cd->u.pipefs.dir);
1854 	cd->u.pipefs.dir = NULL;
1855 }
1856 EXPORT_SYMBOL_GPL(sunrpc_cache_unregister_pipefs);
1857 
1858