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Linux/net/sunrpc/cache.c

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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 
 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 
 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 
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 
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 
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 
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 
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 
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  */
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 
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         schedule_delayed_work(&cache_cleaner, 0);
357 }
358 EXPORT_SYMBOL_GPL(sunrpc_init_cache_detail);
359 
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  */
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  */
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                 schedule_delayed_work(&cache_cleaner, delay);
480 }
481 
482 
483 /*
484  * Clean all caches promptly.  This just calls cache_clean
485  * repeatedly until we are sure that every cache has had a chance to
486  * be fully cleaned
487  */
488 void cache_flush(void)
489 {
490         while (cache_clean() != -1)
491                 cond_resched();
492         while (cache_clean() != -1)
493                 cond_resched();
494 }
495 EXPORT_SYMBOL_GPL(cache_flush);
496 
497 void cache_purge(struct cache_detail *detail)
498 {
499         time_t now = seconds_since_boot();
500         if (detail->flush_time >= now)
501                 now = detail->flush_time + 1;
502         /* 'now' is the maximum value any 'last_refresh' can have */
503         detail->flush_time = now;
504         detail->nextcheck = seconds_since_boot();
505         cache_flush();
506 }
507 EXPORT_SYMBOL_GPL(cache_purge);
508 
509 
510 /*
511  * Deferral and Revisiting of Requests.
512  *
513  * If a cache lookup finds a pending entry, we
514  * need to defer the request and revisit it later.
515  * All deferred requests are stored in a hash table,
516  * indexed by "struct cache_head *".
517  * As it may be wasteful to store a whole request
518  * structure, we allow the request to provide a
519  * deferred form, which must contain a
520  * 'struct cache_deferred_req'
521  * This cache_deferred_req contains a method to allow
522  * it to be revisited when cache info is available
523  */
524 
525 #define DFR_HASHSIZE    (PAGE_SIZE/sizeof(struct list_head))
526 #define DFR_HASH(item)  ((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE)
527 
528 #define DFR_MAX 300     /* ??? */
529 
530 static DEFINE_SPINLOCK(cache_defer_lock);
531 static LIST_HEAD(cache_defer_list);
532 static struct hlist_head cache_defer_hash[DFR_HASHSIZE];
533 static int cache_defer_cnt;
534 
535 static void __unhash_deferred_req(struct cache_deferred_req *dreq)
536 {
537         hlist_del_init(&dreq->hash);
538         if (!list_empty(&dreq->recent)) {
539                 list_del_init(&dreq->recent);
540                 cache_defer_cnt--;
541         }
542 }
543 
544 static void __hash_deferred_req(struct cache_deferred_req *dreq, struct cache_head *item)
545 {
546         int hash = DFR_HASH(item);
547 
548         INIT_LIST_HEAD(&dreq->recent);
549         hlist_add_head(&dreq->hash, &cache_defer_hash[hash]);
550 }
551 
552 static void setup_deferral(struct cache_deferred_req *dreq,
553                            struct cache_head *item,
554                            int count_me)
555 {
556 
557         dreq->item = item;
558 
559         spin_lock(&cache_defer_lock);
560 
561         __hash_deferred_req(dreq, item);
562 
563         if (count_me) {
564                 cache_defer_cnt++;
565                 list_add(&dreq->recent, &cache_defer_list);
566         }
567 
568         spin_unlock(&cache_defer_lock);
569 
570 }
571 
572 struct thread_deferred_req {
573         struct cache_deferred_req handle;
574         struct completion completion;
575 };
576 
577 static void cache_restart_thread(struct cache_deferred_req *dreq, int too_many)
578 {
579         struct thread_deferred_req *dr =
580                 container_of(dreq, struct thread_deferred_req, handle);
581         complete(&dr->completion);
582 }
583 
584 static void cache_wait_req(struct cache_req *req, struct cache_head *item)
585 {
586         struct thread_deferred_req sleeper;
587         struct cache_deferred_req *dreq = &sleeper.handle;
588 
589         sleeper.completion = COMPLETION_INITIALIZER_ONSTACK(sleeper.completion);
590         dreq->revisit = cache_restart_thread;
591 
592         setup_deferral(dreq, item, 0);
593 
594         if (!test_bit(CACHE_PENDING, &item->flags) ||
595             wait_for_completion_interruptible_timeout(
596                     &sleeper.completion, req->thread_wait) <= 0) {
597                 /* The completion wasn't completed, so we need
598                  * to clean up
599                  */
600                 spin_lock(&cache_defer_lock);
601                 if (!hlist_unhashed(&sleeper.handle.hash)) {
602                         __unhash_deferred_req(&sleeper.handle);
603                         spin_unlock(&cache_defer_lock);
604                 } else {
605                         /* cache_revisit_request already removed
606                          * this from the hash table, but hasn't
607                          * called ->revisit yet.  It will very soon
608                          * and we need to wait for it.
609                          */
610                         spin_unlock(&cache_defer_lock);
611                         wait_for_completion(&sleeper.completion);
612                 }
613         }
614 }
615 
616 static void cache_limit_defers(void)
617 {
618         /* Make sure we haven't exceed the limit of allowed deferred
619          * requests.
620          */
621         struct cache_deferred_req *discard = NULL;
622 
623         if (cache_defer_cnt <= DFR_MAX)
624                 return;
625 
626         spin_lock(&cache_defer_lock);
627 
628         /* Consider removing either the first or the last */
629         if (cache_defer_cnt > DFR_MAX) {
630                 if (prandom_u32() & 1)
631                         discard = list_entry(cache_defer_list.next,
632                                              struct cache_deferred_req, recent);
633                 else
634                         discard = list_entry(cache_defer_list.prev,
635                                              struct cache_deferred_req, recent);
636                 __unhash_deferred_req(discard);
637         }
638         spin_unlock(&cache_defer_lock);
639         if (discard)
640                 discard->revisit(discard, 1);
641 }
642 
643 /* Return true if and only if a deferred request is queued. */
644 static bool cache_defer_req(struct cache_req *req, struct cache_head *item)
645 {
646         struct cache_deferred_req *dreq;
647 
648         if (req->thread_wait) {
649                 cache_wait_req(req, item);
650                 if (!test_bit(CACHE_PENDING, &item->flags))
651                         return false;
652         }
653         dreq = req->defer(req);
654         if (dreq == NULL)
655                 return false;
656         setup_deferral(dreq, item, 1);
657         if (!test_bit(CACHE_PENDING, &item->flags))
658                 /* Bit could have been cleared before we managed to
659                  * set up the deferral, so need to revisit just in case
660                  */
661                 cache_revisit_request(item);
662 
663         cache_limit_defers();
664         return true;
665 }
666 
667 static void cache_revisit_request(struct cache_head *item)
668 {
669         struct cache_deferred_req *dreq;
670         struct list_head pending;
671         struct hlist_node *tmp;
672         int hash = DFR_HASH(item);
673 
674         INIT_LIST_HEAD(&pending);
675         spin_lock(&cache_defer_lock);
676 
677         hlist_for_each_entry_safe(dreq, tmp, &cache_defer_hash[hash], hash)
678                 if (dreq->item == item) {
679                         __unhash_deferred_req(dreq);
680                         list_add(&dreq->recent, &pending);
681                 }
682 
683         spin_unlock(&cache_defer_lock);
684 
685         while (!list_empty(&pending)) {
686                 dreq = list_entry(pending.next, struct cache_deferred_req, recent);
687                 list_del_init(&dreq->recent);
688                 dreq->revisit(dreq, 0);
689         }
690 }
691 
692 void cache_clean_deferred(void *owner)
693 {
694         struct cache_deferred_req *dreq, *tmp;
695         struct list_head pending;
696 
697 
698         INIT_LIST_HEAD(&pending);
699         spin_lock(&cache_defer_lock);
700 
701         list_for_each_entry_safe(dreq, tmp, &cache_defer_list, recent) {
702                 if (dreq->owner == owner) {
703                         __unhash_deferred_req(dreq);
704                         list_add(&dreq->recent, &pending);
705                 }
706         }
707         spin_unlock(&cache_defer_lock);
708 
709         while (!list_empty(&pending)) {
710                 dreq = list_entry(pending.next, struct cache_deferred_req, recent);
711                 list_del_init(&dreq->recent);
712                 dreq->revisit(dreq, 1);
713         }
714 }
715 
716 /*
717  * communicate with user-space
718  *
719  * We have a magic /proc file - /proc/sunrpc/<cachename>/channel.
720  * On read, you get a full request, or block.
721  * On write, an update request is processed.
722  * Poll works if anything to read, and always allows write.
723  *
724  * Implemented by linked list of requests.  Each open file has
725  * a ->private that also exists in this list.  New requests are added
726  * to the end and may wakeup and preceding readers.
727  * New readers are added to the head.  If, on read, an item is found with
728  * CACHE_UPCALLING clear, we free it from the list.
729  *
730  */
731 
732 static DEFINE_SPINLOCK(queue_lock);
733 static DEFINE_MUTEX(queue_io_mutex);
734 
735 struct cache_queue {
736         struct list_head        list;
737         int                     reader; /* if 0, then request */
738 };
739 struct cache_request {
740         struct cache_queue      q;
741         struct cache_head       *item;
742         char                    * buf;
743         int                     len;
744         int                     readers;
745 };
746 struct cache_reader {
747         struct cache_queue      q;
748         int                     offset; /* if non-0, we have a refcnt on next request */
749 };
750 
751 static int cache_request(struct cache_detail *detail,
752                                struct cache_request *crq)
753 {
754         char *bp = crq->buf;
755         int len = PAGE_SIZE;
756 
757         detail->cache_request(detail, crq->item, &bp, &len);
758         if (len < 0)
759                 return -EAGAIN;
760         return PAGE_SIZE - len;
761 }
762 
763 static ssize_t cache_read(struct file *filp, char __user *buf, size_t count,
764                           loff_t *ppos, struct cache_detail *cd)
765 {
766         struct cache_reader *rp = filp->private_data;
767         struct cache_request *rq;
768         struct inode *inode = file_inode(filp);
769         int err;
770 
771         if (count == 0)
772                 return 0;
773 
774         inode_lock(inode); /* protect against multiple concurrent
775                               * readers on this file */
776  again:
777         spin_lock(&queue_lock);
778         /* need to find next request */
779         while (rp->q.list.next != &cd->queue &&
780                list_entry(rp->q.list.next, struct cache_queue, list)
781                ->reader) {
782                 struct list_head *next = rp->q.list.next;
783                 list_move(&rp->q.list, next);
784         }
785         if (rp->q.list.next == &cd->queue) {
786                 spin_unlock(&queue_lock);
787                 inode_unlock(inode);
788                 WARN_ON_ONCE(rp->offset);
789                 return 0;
790         }
791         rq = container_of(rp->q.list.next, struct cache_request, q.list);
792         WARN_ON_ONCE(rq->q.reader);
793         if (rp->offset == 0)
794                 rq->readers++;
795         spin_unlock(&queue_lock);
796 
797         if (rq->len == 0) {
798                 err = cache_request(cd, rq);
799                 if (err < 0)
800                         goto out;
801                 rq->len = err;
802         }
803 
804         if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) {
805                 err = -EAGAIN;
806                 spin_lock(&queue_lock);
807                 list_move(&rp->q.list, &rq->q.list);
808                 spin_unlock(&queue_lock);
809         } else {
810                 if (rp->offset + count > rq->len)
811                         count = rq->len - rp->offset;
812                 err = -EFAULT;
813                 if (copy_to_user(buf, rq->buf + rp->offset, count))
814                         goto out;
815                 rp->offset += count;
816                 if (rp->offset >= rq->len) {
817                         rp->offset = 0;
818                         spin_lock(&queue_lock);
819                         list_move(&rp->q.list, &rq->q.list);
820                         spin_unlock(&queue_lock);
821                 }
822                 err = 0;
823         }
824  out:
825         if (rp->offset == 0) {
826                 /* need to release rq */
827                 spin_lock(&queue_lock);
828                 rq->readers--;
829                 if (rq->readers == 0 &&
830                     !test_bit(CACHE_PENDING, &rq->item->flags)) {
831                         list_del(&rq->q.list);
832                         spin_unlock(&queue_lock);
833                         cache_put(rq->item, cd);
834                         kfree(rq->buf);
835                         kfree(rq);
836                 } else
837                         spin_unlock(&queue_lock);
838         }
839         if (err == -EAGAIN)
840                 goto again;
841         inode_unlock(inode);
842         return err ? err :  count;
843 }
844 
845 static ssize_t cache_do_downcall(char *kaddr, const char __user *buf,
846                                  size_t count, struct cache_detail *cd)
847 {
848         ssize_t ret;
849 
850         if (count == 0)
851                 return -EINVAL;
852         if (copy_from_user(kaddr, buf, count))
853                 return -EFAULT;
854         kaddr[count] = '\0';
855         ret = cd->cache_parse(cd, kaddr, count);
856         if (!ret)
857                 ret = count;
858         return ret;
859 }
860 
861 static ssize_t cache_slow_downcall(const char __user *buf,
862                                    size_t count, struct cache_detail *cd)
863 {
864         static char write_buf[8192]; /* protected by queue_io_mutex */
865         ssize_t ret = -EINVAL;
866 
867         if (count >= sizeof(write_buf))
868                 goto out;
869         mutex_lock(&queue_io_mutex);
870         ret = cache_do_downcall(write_buf, buf, count, cd);
871         mutex_unlock(&queue_io_mutex);
872 out:
873         return ret;
874 }
875 
876 static ssize_t cache_downcall(struct address_space *mapping,
877                               const char __user *buf,
878                               size_t count, struct cache_detail *cd)
879 {
880         struct page *page;
881         char *kaddr;
882         ssize_t ret = -ENOMEM;
883 
884         if (count >= PAGE_SIZE)
885                 goto out_slow;
886 
887         page = find_or_create_page(mapping, 0, GFP_KERNEL);
888         if (!page)
889                 goto out_slow;
890 
891         kaddr = kmap(page);
892         ret = cache_do_downcall(kaddr, buf, count, cd);
893         kunmap(page);
894         unlock_page(page);
895         put_page(page);
896         return ret;
897 out_slow:
898         return cache_slow_downcall(buf, count, cd);
899 }
900 
901 static ssize_t cache_write(struct file *filp, const char __user *buf,
902                            size_t count, loff_t *ppos,
903                            struct cache_detail *cd)
904 {
905         struct address_space *mapping = filp->f_mapping;
906         struct inode *inode = file_inode(filp);
907         ssize_t ret = -EINVAL;
908 
909         if (!cd->cache_parse)
910                 goto out;
911 
912         inode_lock(inode);
913         ret = cache_downcall(mapping, buf, count, cd);
914         inode_unlock(inode);
915 out:
916         return ret;
917 }
918 
919 static DECLARE_WAIT_QUEUE_HEAD(queue_wait);
920 
921 static unsigned int cache_poll(struct file *filp, poll_table *wait,
922                                struct cache_detail *cd)
923 {
924         unsigned int mask;
925         struct cache_reader *rp = filp->private_data;
926         struct cache_queue *cq;
927 
928         poll_wait(filp, &queue_wait, wait);
929 
930         /* alway allow write */
931         mask = POLLOUT | POLLWRNORM;
932 
933         if (!rp)
934                 return mask;
935 
936         spin_lock(&queue_lock);
937 
938         for (cq= &rp->q; &cq->list != &cd->queue;
939              cq = list_entry(cq->list.next, struct cache_queue, list))
940                 if (!cq->reader) {
941                         mask |= POLLIN | POLLRDNORM;
942                         break;
943                 }
944         spin_unlock(&queue_lock);
945         return mask;
946 }
947 
948 static int cache_ioctl(struct inode *ino, struct file *filp,
949                        unsigned int cmd, unsigned long arg,
950                        struct cache_detail *cd)
951 {
952         int len = 0;
953         struct cache_reader *rp = filp->private_data;
954         struct cache_queue *cq;
955 
956         if (cmd != FIONREAD || !rp)
957                 return -EINVAL;
958 
959         spin_lock(&queue_lock);
960 
961         /* only find the length remaining in current request,
962          * or the length of the next request
963          */
964         for (cq= &rp->q; &cq->list != &cd->queue;
965              cq = list_entry(cq->list.next, struct cache_queue, list))
966                 if (!cq->reader) {
967                         struct cache_request *cr =
968                                 container_of(cq, struct cache_request, q);
969                         len = cr->len - rp->offset;
970                         break;
971                 }
972         spin_unlock(&queue_lock);
973 
974         return put_user(len, (int __user *)arg);
975 }
976 
977 static int cache_open(struct inode *inode, struct file *filp,
978                       struct cache_detail *cd)
979 {
980         struct cache_reader *rp = NULL;
981 
982         if (!cd || !try_module_get(cd->owner))
983                 return -EACCES;
984         nonseekable_open(inode, filp);
985         if (filp->f_mode & FMODE_READ) {
986                 rp = kmalloc(sizeof(*rp), GFP_KERNEL);
987                 if (!rp) {
988                         module_put(cd->owner);
989                         return -ENOMEM;
990                 }
991                 rp->offset = 0;
992                 rp->q.reader = 1;
993                 atomic_inc(&cd->readers);
994                 spin_lock(&queue_lock);
995                 list_add(&rp->q.list, &cd->queue);
996                 spin_unlock(&queue_lock);
997         }
998         filp->private_data = rp;
999         return 0;
1000 }
1001 
1002 static int cache_release(struct inode *inode, struct file *filp,
1003                          struct cache_detail *cd)
1004 {
1005         struct cache_reader *rp = filp->private_data;
1006 
1007         if (rp) {
1008                 spin_lock(&queue_lock);
1009                 if (rp->offset) {
1010                         struct cache_queue *cq;
1011                         for (cq= &rp->q; &cq->list != &cd->queue;
1012                              cq = list_entry(cq->list.next, struct cache_queue, list))
1013                                 if (!cq->reader) {
1014                                         container_of(cq, struct cache_request, q)
1015                                                 ->readers--;
1016                                         break;
1017                                 }
1018                         rp->offset = 0;
1019                 }
1020                 list_del(&rp->q.list);
1021                 spin_unlock(&queue_lock);
1022 
1023                 filp->private_data = NULL;
1024                 kfree(rp);
1025 
1026                 cd->last_close = seconds_since_boot();
1027                 atomic_dec(&cd->readers);
1028         }
1029         module_put(cd->owner);
1030         return 0;
1031 }
1032 
1033 
1034 
1035 static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch)
1036 {
1037         struct cache_queue *cq, *tmp;
1038         struct cache_request *cr;
1039         struct list_head dequeued;
1040 
1041         INIT_LIST_HEAD(&dequeued);
1042         spin_lock(&queue_lock);
1043         list_for_each_entry_safe(cq, tmp, &detail->queue, list)
1044                 if (!cq->reader) {
1045                         cr = container_of(cq, struct cache_request, q);
1046                         if (cr->item != ch)
1047                                 continue;
1048                         if (test_bit(CACHE_PENDING, &ch->flags))
1049                                 /* Lost a race and it is pending again */
1050                                 break;
1051                         if (cr->readers != 0)
1052                                 continue;
1053                         list_move(&cr->q.list, &dequeued);
1054                 }
1055         spin_unlock(&queue_lock);
1056         while (!list_empty(&dequeued)) {
1057                 cr = list_entry(dequeued.next, struct cache_request, q.list);
1058                 list_del(&cr->q.list);
1059                 cache_put(cr->item, detail);
1060                 kfree(cr->buf);
1061                 kfree(cr);
1062         }
1063 }
1064 
1065 /*
1066  * Support routines for text-based upcalls.
1067  * Fields are separated by spaces.
1068  * Fields are either mangled to quote space tab newline slosh with slosh
1069  * or a hexified with a leading \x
1070  * Record is terminated with newline.
1071  *
1072  */
1073 
1074 void qword_add(char **bpp, int *lp, char *str)
1075 {
1076         char *bp = *bpp;
1077         int len = *lp;
1078         int ret;
1079 
1080         if (len < 0) return;
1081 
1082         ret = string_escape_str(str, bp, len, ESCAPE_OCTAL, "\\ \n\t");
1083         if (ret >= len) {
1084                 bp += len;
1085                 len = -1;
1086         } else {
1087                 bp += ret;
1088                 len -= ret;
1089                 *bp++ = ' ';
1090                 len--;
1091         }
1092         *bpp = bp;
1093         *lp = len;
1094 }
1095 EXPORT_SYMBOL_GPL(qword_add);
1096 
1097 void qword_addhex(char **bpp, int *lp, char *buf, int blen)
1098 {
1099         char *bp = *bpp;
1100         int len = *lp;
1101 
1102         if (len < 0) return;
1103 
1104         if (len > 2) {
1105                 *bp++ = '\\';
1106                 *bp++ = 'x';
1107                 len -= 2;
1108                 while (blen && len >= 2) {
1109                         bp = hex_byte_pack(bp, *buf++);
1110                         len -= 2;
1111                         blen--;
1112                 }
1113         }
1114         if (blen || len<1) len = -1;
1115         else {
1116                 *bp++ = ' ';
1117                 len--;
1118         }
1119         *bpp = bp;
1120         *lp = len;
1121 }
1122 EXPORT_SYMBOL_GPL(qword_addhex);
1123 
1124 static void warn_no_listener(struct cache_detail *detail)
1125 {
1126         if (detail->last_warn != detail->last_close) {
1127                 detail->last_warn = detail->last_close;
1128                 if (detail->warn_no_listener)
1129                         detail->warn_no_listener(detail, detail->last_close != 0);
1130         }
1131 }
1132 
1133 static bool cache_listeners_exist(struct cache_detail *detail)
1134 {
1135         if (atomic_read(&detail->readers))
1136                 return true;
1137         if (detail->last_close == 0)
1138                 /* This cache was never opened */
1139                 return false;
1140         if (detail->last_close < seconds_since_boot() - 30)
1141                 /*
1142                  * We allow for the possibility that someone might
1143                  * restart a userspace daemon without restarting the
1144                  * server; but after 30 seconds, we give up.
1145                  */
1146                  return false;
1147         return true;
1148 }
1149 
1150 /*
1151  * register an upcall request to user-space and queue it up for read() by the
1152  * upcall daemon.
1153  *
1154  * Each request is at most one page long.
1155  */
1156 int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h)
1157 {
1158 
1159         char *buf;
1160         struct cache_request *crq;
1161         int ret = 0;
1162 
1163         if (!detail->cache_request)
1164                 return -EINVAL;
1165 
1166         if (!cache_listeners_exist(detail)) {
1167                 warn_no_listener(detail);
1168                 return -EINVAL;
1169         }
1170         if (test_bit(CACHE_CLEANED, &h->flags))
1171                 /* Too late to make an upcall */
1172                 return -EAGAIN;
1173 
1174         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
1175         if (!buf)
1176                 return -EAGAIN;
1177 
1178         crq = kmalloc(sizeof (*crq), GFP_KERNEL);
1179         if (!crq) {
1180                 kfree(buf);
1181                 return -EAGAIN;
1182         }
1183 
1184         crq->q.reader = 0;
1185         crq->buf = buf;
1186         crq->len = 0;
1187         crq->readers = 0;
1188         spin_lock(&queue_lock);
1189         if (test_bit(CACHE_PENDING, &h->flags)) {
1190                 crq->item = cache_get(h);
1191                 list_add_tail(&crq->q.list, &detail->queue);
1192         } else
1193                 /* Lost a race, no longer PENDING, so don't enqueue */
1194                 ret = -EAGAIN;
1195         spin_unlock(&queue_lock);
1196         wake_up(&queue_wait);
1197         if (ret == -EAGAIN) {
1198                 kfree(buf);
1199                 kfree(crq);
1200         }
1201         return ret;
1202 }
1203 EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall);
1204 
1205 /*
1206  * parse a message from user-space and pass it
1207  * to an appropriate cache
1208  * Messages are, like requests, separated into fields by
1209  * spaces and dequotes as \xHEXSTRING or embedded \nnn octal
1210  *
1211  * Message is
1212  *   reply cachename expiry key ... content....
1213  *
1214  * key and content are both parsed by cache
1215  */
1216 
1217 int qword_get(char **bpp, char *dest, int bufsize)
1218 {
1219         /* return bytes copied, or -1 on error */
1220         char *bp = *bpp;
1221         int len = 0;
1222 
1223         while (*bp == ' ') bp++;
1224 
1225         if (bp[0] == '\\' && bp[1] == 'x') {
1226                 /* HEX STRING */
1227                 bp += 2;
1228                 while (len < bufsize - 1) {
1229                         int h, l;
1230 
1231                         h = hex_to_bin(bp[0]);
1232                         if (h < 0)
1233                                 break;
1234 
1235                         l = hex_to_bin(bp[1]);
1236                         if (l < 0)
1237                                 break;
1238 
1239                         *dest++ = (h << 4) | l;
1240                         bp += 2;
1241                         len++;
1242                 }
1243         } else {
1244                 /* text with \nnn octal quoting */
1245                 while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) {
1246                         if (*bp == '\\' &&
1247                             isodigit(bp[1]) && (bp[1] <= '3') &&
1248                             isodigit(bp[2]) &&
1249                             isodigit(bp[3])) {
1250                                 int byte = (*++bp -'');
1251                                 bp++;
1252                                 byte = (byte << 3) | (*bp++ - '');
1253                                 byte = (byte << 3) | (*bp++ - '');
1254                                 *dest++ = byte;
1255                                 len++;
1256                         } else {
1257                                 *dest++ = *bp++;
1258                                 len++;
1259                         }
1260                 }
1261         }
1262 
1263         if (*bp != ' ' && *bp != '\n' && *bp != '\0')
1264                 return -1;
1265         while (*bp == ' ') bp++;
1266         *bpp = bp;
1267         *dest = '\0';
1268         return len;
1269 }
1270 EXPORT_SYMBOL_GPL(qword_get);
1271 
1272 
1273 /*
1274  * support /proc/sunrpc/cache/$CACHENAME/content
1275  * as a seqfile.
1276  * We call ->cache_show passing NULL for the item to
1277  * get a header, then pass each real item in the cache
1278  */
1279 
1280 void *cache_seq_start(struct seq_file *m, loff_t *pos)
1281         __acquires(cd->hash_lock)
1282 {
1283         loff_t n = *pos;
1284         unsigned int hash, entry;
1285         struct cache_head *ch;
1286         struct cache_detail *cd = m->private;
1287 
1288         read_lock(&cd->hash_lock);
1289         if (!n--)
1290                 return SEQ_START_TOKEN;
1291         hash = n >> 32;
1292         entry = n & ((1LL<<32) - 1);
1293 
1294         hlist_for_each_entry(ch, &cd->hash_table[hash], cache_list)
1295                 if (!entry--)
1296                         return ch;
1297         n &= ~((1LL<<32) - 1);
1298         do {
1299                 hash++;
1300                 n += 1LL<<32;
1301         } while(hash < cd->hash_size &&
1302                 hlist_empty(&cd->hash_table[hash]));
1303         if (hash >= cd->hash_size)
1304                 return NULL;
1305         *pos = n+1;
1306         return hlist_entry_safe(cd->hash_table[hash].first,
1307                                 struct cache_head, cache_list);
1308 }
1309 EXPORT_SYMBOL_GPL(cache_seq_start);
1310 
1311 void *cache_seq_next(struct seq_file *m, void *p, loff_t *pos)
1312 {
1313         struct cache_head *ch = p;
1314         int hash = (*pos >> 32);
1315         struct cache_detail *cd = m->private;
1316 
1317         if (p == SEQ_START_TOKEN)
1318                 hash = 0;
1319         else if (ch->cache_list.next == NULL) {
1320                 hash++;
1321                 *pos += 1LL<<32;
1322         } else {
1323                 ++*pos;
1324                 return hlist_entry_safe(ch->cache_list.next,
1325                                         struct cache_head, cache_list);
1326         }
1327         *pos &= ~((1LL<<32) - 1);
1328         while (hash < cd->hash_size &&
1329                hlist_empty(&cd->hash_table[hash])) {
1330                 hash++;
1331                 *pos += 1LL<<32;
1332         }
1333         if (hash >= cd->hash_size)
1334                 return NULL;
1335         ++*pos;
1336         return hlist_entry_safe(cd->hash_table[hash].first,
1337                                 struct cache_head, cache_list);
1338 }
1339 EXPORT_SYMBOL_GPL(cache_seq_next);
1340 
1341 void cache_seq_stop(struct seq_file *m, void *p)
1342         __releases(cd->hash_lock)
1343 {
1344         struct cache_detail *cd = m->private;
1345         read_unlock(&cd->hash_lock);
1346 }
1347 EXPORT_SYMBOL_GPL(cache_seq_stop);
1348 
1349 static int c_show(struct seq_file *m, void *p)
1350 {
1351         struct cache_head *cp = p;
1352         struct cache_detail *cd = m->private;
1353 
1354         if (p == SEQ_START_TOKEN)
1355                 return cd->cache_show(m, cd, NULL);
1356 
1357         ifdebug(CACHE)
1358                 seq_printf(m, "# expiry=%ld refcnt=%d flags=%lx\n",
1359                            convert_to_wallclock(cp->expiry_time),
1360                            atomic_read(&cp->ref.refcount), cp->flags);
1361         cache_get(cp);
1362         if (cache_check(cd, cp, NULL))
1363                 /* cache_check does a cache_put on failure */
1364                 seq_printf(m, "# ");
1365         else {
1366                 if (cache_is_expired(cd, cp))
1367                         seq_printf(m, "# ");
1368                 cache_put(cp, cd);
1369         }
1370 
1371         return cd->cache_show(m, cd, cp);
1372 }
1373 
1374 static const struct seq_operations cache_content_op = {
1375         .start  = cache_seq_start,
1376         .next   = cache_seq_next,
1377         .stop   = cache_seq_stop,
1378         .show   = c_show,
1379 };
1380 
1381 static int content_open(struct inode *inode, struct file *file,
1382                         struct cache_detail *cd)
1383 {
1384         struct seq_file *seq;
1385         int err;
1386 
1387         if (!cd || !try_module_get(cd->owner))
1388                 return -EACCES;
1389 
1390         err = seq_open(file, &cache_content_op);
1391         if (err) {
1392                 module_put(cd->owner);
1393                 return err;
1394         }
1395 
1396         seq = file->private_data;
1397         seq->private = cd;
1398         return 0;
1399 }
1400 
1401 static int content_release(struct inode *inode, struct file *file,
1402                 struct cache_detail *cd)
1403 {
1404         int ret = seq_release(inode, file);
1405         module_put(cd->owner);
1406         return ret;
1407 }
1408 
1409 static int open_flush(struct inode *inode, struct file *file,
1410                         struct cache_detail *cd)
1411 {
1412         if (!cd || !try_module_get(cd->owner))
1413                 return -EACCES;
1414         return nonseekable_open(inode, file);
1415 }
1416 
1417 static int release_flush(struct inode *inode, struct file *file,
1418                         struct cache_detail *cd)
1419 {
1420         module_put(cd->owner);
1421         return 0;
1422 }
1423 
1424 static ssize_t read_flush(struct file *file, char __user *buf,
1425                           size_t count, loff_t *ppos,
1426                           struct cache_detail *cd)
1427 {
1428         char tbuf[22];
1429         unsigned long p = *ppos;
1430         size_t len;
1431 
1432         snprintf(tbuf, sizeof(tbuf), "%lu\n", convert_to_wallclock(cd->flush_time));
1433         len = strlen(tbuf);
1434         if (p >= len)
1435                 return 0;
1436         len -= p;
1437         if (len > count)
1438                 len = count;
1439         if (copy_to_user(buf, (void*)(tbuf+p), len))
1440                 return -EFAULT;
1441         *ppos += len;
1442         return len;
1443 }
1444 
1445 static ssize_t write_flush(struct file *file, const char __user *buf,
1446                            size_t count, loff_t *ppos,
1447                            struct cache_detail *cd)
1448 {
1449         char tbuf[20];
1450         char *bp, *ep;
1451         time_t then, now;
1452 
1453         if (*ppos || count > sizeof(tbuf)-1)
1454                 return -EINVAL;
1455         if (copy_from_user(tbuf, buf, count))
1456                 return -EFAULT;
1457         tbuf[count] = 0;
1458         simple_strtoul(tbuf, &ep, 0);
1459         if (*ep && *ep != '\n')
1460                 return -EINVAL;
1461 
1462         bp = tbuf;
1463         then = get_expiry(&bp);
1464         now = seconds_since_boot();
1465         cd->nextcheck = now;
1466         /* Can only set flush_time to 1 second beyond "now", or
1467          * possibly 1 second beyond flushtime.  This is because
1468          * flush_time never goes backwards so it mustn't get too far
1469          * ahead of time.
1470          */
1471         if (then >= now) {
1472                 /* Want to flush everything, so behave like cache_purge() */
1473                 if (cd->flush_time >= now)
1474                         now = cd->flush_time + 1;
1475                 then = now;
1476         }
1477 
1478         cd->flush_time = then;
1479         cache_flush();
1480 
1481         *ppos += count;
1482         return count;
1483 }
1484 
1485 static ssize_t cache_read_procfs(struct file *filp, char __user *buf,
1486                                  size_t count, loff_t *ppos)
1487 {
1488         struct cache_detail *cd = PDE_DATA(file_inode(filp));
1489 
1490         return cache_read(filp, buf, count, ppos, cd);
1491 }
1492 
1493 static ssize_t cache_write_procfs(struct file *filp, const char __user *buf,
1494                                   size_t count, loff_t *ppos)
1495 {
1496         struct cache_detail *cd = PDE_DATA(file_inode(filp));
1497 
1498         return cache_write(filp, buf, count, ppos, cd);
1499 }
1500 
1501 static unsigned int cache_poll_procfs(struct file *filp, poll_table *wait)
1502 {
1503         struct cache_detail *cd = PDE_DATA(file_inode(filp));
1504 
1505         return cache_poll(filp, wait, cd);
1506 }
1507 
1508 static long cache_ioctl_procfs(struct file *filp,
1509                                unsigned int cmd, unsigned long arg)
1510 {
1511         struct inode *inode = file_inode(filp);
1512         struct cache_detail *cd = PDE_DATA(inode);
1513 
1514         return cache_ioctl(inode, filp, cmd, arg, cd);
1515 }
1516 
1517 static int cache_open_procfs(struct inode *inode, struct file *filp)
1518 {
1519         struct cache_detail *cd = PDE_DATA(inode);
1520 
1521         return cache_open(inode, filp, cd);
1522 }
1523 
1524 static int cache_release_procfs(struct inode *inode, struct file *filp)
1525 {
1526         struct cache_detail *cd = PDE_DATA(inode);
1527 
1528         return cache_release(inode, filp, cd);
1529 }
1530 
1531 static const struct file_operations cache_file_operations_procfs = {
1532         .owner          = THIS_MODULE,
1533         .llseek         = no_llseek,
1534         .read           = cache_read_procfs,
1535         .write          = cache_write_procfs,
1536         .poll           = cache_poll_procfs,
1537         .unlocked_ioctl = cache_ioctl_procfs, /* for FIONREAD */
1538         .open           = cache_open_procfs,
1539         .release        = cache_release_procfs,
1540 };
1541 
1542 static int content_open_procfs(struct inode *inode, struct file *filp)
1543 {
1544         struct cache_detail *cd = PDE_DATA(inode);
1545 
1546         return content_open(inode, filp, cd);
1547 }
1548 
1549 static int content_release_procfs(struct inode *inode, struct file *filp)
1550 {
1551         struct cache_detail *cd = PDE_DATA(inode);
1552 
1553         return content_release(inode, filp, cd);
1554 }
1555 
1556 static const struct file_operations content_file_operations_procfs = {
1557         .open           = content_open_procfs,
1558         .read           = seq_read,
1559         .llseek         = seq_lseek,
1560         .release        = content_release_procfs,
1561 };
1562 
1563 static int open_flush_procfs(struct inode *inode, struct file *filp)
1564 {
1565         struct cache_detail *cd = PDE_DATA(inode);
1566 
1567         return open_flush(inode, filp, cd);
1568 }
1569 
1570 static int release_flush_procfs(struct inode *inode, struct file *filp)
1571 {
1572         struct cache_detail *cd = PDE_DATA(inode);
1573 
1574         return release_flush(inode, filp, cd);
1575 }
1576 
1577 static ssize_t read_flush_procfs(struct file *filp, char __user *buf,
1578                             size_t count, loff_t *ppos)
1579 {
1580         struct cache_detail *cd = PDE_DATA(file_inode(filp));
1581 
1582         return read_flush(filp, buf, count, ppos, cd);
1583 }
1584 
1585 static ssize_t write_flush_procfs(struct file *filp,
1586                                   const char __user *buf,
1587                                   size_t count, loff_t *ppos)
1588 {
1589         struct cache_detail *cd = PDE_DATA(file_inode(filp));
1590 
1591         return write_flush(filp, buf, count, ppos, cd);
1592 }
1593 
1594 static const struct file_operations cache_flush_operations_procfs = {
1595         .open           = open_flush_procfs,
1596         .read           = read_flush_procfs,
1597         .write          = write_flush_procfs,
1598         .release        = release_flush_procfs,
1599         .llseek         = no_llseek,
1600 };
1601 
1602 static void remove_cache_proc_entries(struct cache_detail *cd, struct net *net)
1603 {
1604         struct sunrpc_net *sn;
1605 
1606         if (cd->u.procfs.proc_ent == NULL)
1607                 return;
1608         if (cd->u.procfs.flush_ent)
1609                 remove_proc_entry("flush", cd->u.procfs.proc_ent);
1610         if (cd->u.procfs.channel_ent)
1611                 remove_proc_entry("channel", cd->u.procfs.proc_ent);
1612         if (cd->u.procfs.content_ent)
1613                 remove_proc_entry("content", cd->u.procfs.proc_ent);
1614         cd->u.procfs.proc_ent = NULL;
1615         sn = net_generic(net, sunrpc_net_id);
1616         remove_proc_entry(cd->name, sn->proc_net_rpc);
1617 }
1618 
1619 #ifdef CONFIG_PROC_FS
1620 static int create_cache_proc_entries(struct cache_detail *cd, struct net *net)
1621 {
1622         struct proc_dir_entry *p;
1623         struct sunrpc_net *sn;
1624 
1625         sn = net_generic(net, sunrpc_net_id);
1626         cd->u.procfs.proc_ent = proc_mkdir(cd->name, sn->proc_net_rpc);
1627         if (cd->u.procfs.proc_ent == NULL)
1628                 goto out_nomem;
1629         cd->u.procfs.channel_ent = NULL;
1630         cd->u.procfs.content_ent = NULL;
1631 
1632         p = proc_create_data("flush", S_IFREG|S_IRUSR|S_IWUSR,
1633                              cd->u.procfs.proc_ent,
1634                              &cache_flush_operations_procfs, cd);
1635         cd->u.procfs.flush_ent = p;
1636         if (p == NULL)
1637                 goto out_nomem;
1638 
1639         if (cd->cache_request || cd->cache_parse) {
1640                 p = proc_create_data("channel", S_IFREG|S_IRUSR|S_IWUSR,
1641                                      cd->u.procfs.proc_ent,
1642                                      &cache_file_operations_procfs, cd);
1643                 cd->u.procfs.channel_ent = p;
1644                 if (p == NULL)
1645                         goto out_nomem;
1646         }
1647         if (cd->cache_show) {
1648                 p = proc_create_data("content", S_IFREG|S_IRUSR,
1649                                 cd->u.procfs.proc_ent,
1650                                 &content_file_operations_procfs, cd);
1651                 cd->u.procfs.content_ent = p;
1652                 if (p == NULL)
1653                         goto out_nomem;
1654         }
1655         return 0;
1656 out_nomem:
1657         remove_cache_proc_entries(cd, net);
1658         return -ENOMEM;
1659 }
1660 #else /* CONFIG_PROC_FS */
1661 static int create_cache_proc_entries(struct cache_detail *cd, struct net *net)
1662 {
1663         return 0;
1664 }
1665 #endif
1666 
1667 void __init cache_initialize(void)
1668 {
1669         INIT_DEFERRABLE_WORK(&cache_cleaner, do_cache_clean);
1670 }
1671 
1672 int cache_register_net(struct cache_detail *cd, struct net *net)
1673 {
1674         int ret;
1675 
1676         sunrpc_init_cache_detail(cd);
1677         ret = create_cache_proc_entries(cd, net);
1678         if (ret)
1679                 sunrpc_destroy_cache_detail(cd);
1680         return ret;
1681 }
1682 EXPORT_SYMBOL_GPL(cache_register_net);
1683 
1684 void cache_unregister_net(struct cache_detail *cd, struct net *net)
1685 {
1686         remove_cache_proc_entries(cd, net);
1687         sunrpc_destroy_cache_detail(cd);
1688 }
1689 EXPORT_SYMBOL_GPL(cache_unregister_net);
1690 
1691 struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net)
1692 {
1693         struct cache_detail *cd;
1694         int i;
1695 
1696         cd = kmemdup(tmpl, sizeof(struct cache_detail), GFP_KERNEL);
1697         if (cd == NULL)
1698                 return ERR_PTR(-ENOMEM);
1699 
1700         cd->hash_table = kzalloc(cd->hash_size * sizeof(struct hlist_head),
1701                                  GFP_KERNEL);
1702         if (cd->hash_table == NULL) {
1703                 kfree(cd);
1704                 return ERR_PTR(-ENOMEM);
1705         }
1706 
1707         for (i = 0; i < cd->hash_size; i++)
1708                 INIT_HLIST_HEAD(&cd->hash_table[i]);
1709         cd->net = net;
1710         return cd;
1711 }
1712 EXPORT_SYMBOL_GPL(cache_create_net);
1713 
1714 void cache_destroy_net(struct cache_detail *cd, struct net *net)
1715 {
1716         kfree(cd->hash_table);
1717         kfree(cd);
1718 }
1719 EXPORT_SYMBOL_GPL(cache_destroy_net);
1720 
1721 static ssize_t cache_read_pipefs(struct file *filp, char __user *buf,
1722                                  size_t count, loff_t *ppos)
1723 {
1724         struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1725 
1726         return cache_read(filp, buf, count, ppos, cd);
1727 }
1728 
1729 static ssize_t cache_write_pipefs(struct file *filp, const char __user *buf,
1730                                   size_t count, loff_t *ppos)
1731 {
1732         struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1733 
1734         return cache_write(filp, buf, count, ppos, cd);
1735 }
1736 
1737 static unsigned int cache_poll_pipefs(struct file *filp, poll_table *wait)
1738 {
1739         struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1740 
1741         return cache_poll(filp, wait, cd);
1742 }
1743 
1744 static long cache_ioctl_pipefs(struct file *filp,
1745                               unsigned int cmd, unsigned long arg)
1746 {
1747         struct inode *inode = file_inode(filp);
1748         struct cache_detail *cd = RPC_I(inode)->private;
1749 
1750         return cache_ioctl(inode, filp, cmd, arg, cd);
1751 }
1752 
1753 static int cache_open_pipefs(struct inode *inode, struct file *filp)
1754 {
1755         struct cache_detail *cd = RPC_I(inode)->private;
1756 
1757         return cache_open(inode, filp, cd);
1758 }
1759 
1760 static int cache_release_pipefs(struct inode *inode, struct file *filp)
1761 {
1762         struct cache_detail *cd = RPC_I(inode)->private;
1763 
1764         return cache_release(inode, filp, cd);
1765 }
1766 
1767 const struct file_operations cache_file_operations_pipefs = {
1768         .owner          = THIS_MODULE,
1769         .llseek         = no_llseek,
1770         .read           = cache_read_pipefs,
1771         .write          = cache_write_pipefs,
1772         .poll           = cache_poll_pipefs,
1773         .unlocked_ioctl = cache_ioctl_pipefs, /* for FIONREAD */
1774         .open           = cache_open_pipefs,
1775         .release        = cache_release_pipefs,
1776 };
1777 
1778 static int content_open_pipefs(struct inode *inode, struct file *filp)
1779 {
1780         struct cache_detail *cd = RPC_I(inode)->private;
1781 
1782         return content_open(inode, filp, cd);
1783 }
1784 
1785 static int content_release_pipefs(struct inode *inode, struct file *filp)
1786 {
1787         struct cache_detail *cd = RPC_I(inode)->private;
1788 
1789         return content_release(inode, filp, cd);
1790 }
1791 
1792 const struct file_operations content_file_operations_pipefs = {
1793         .open           = content_open_pipefs,
1794         .read           = seq_read,
1795         .llseek         = seq_lseek,
1796         .release        = content_release_pipefs,
1797 };
1798 
1799 static int open_flush_pipefs(struct inode *inode, struct file *filp)
1800 {
1801         struct cache_detail *cd = RPC_I(inode)->private;
1802 
1803         return open_flush(inode, filp, cd);
1804 }
1805 
1806 static int release_flush_pipefs(struct inode *inode, struct file *filp)
1807 {
1808         struct cache_detail *cd = RPC_I(inode)->private;
1809 
1810         return release_flush(inode, filp, cd);
1811 }
1812 
1813 static ssize_t read_flush_pipefs(struct file *filp, char __user *buf,
1814                             size_t count, loff_t *ppos)
1815 {
1816         struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1817 
1818         return read_flush(filp, buf, count, ppos, cd);
1819 }
1820 
1821 static ssize_t write_flush_pipefs(struct file *filp,
1822                                   const char __user *buf,
1823                                   size_t count, loff_t *ppos)
1824 {
1825         struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1826 
1827         return write_flush(filp, buf, count, ppos, cd);
1828 }
1829 
1830 const struct file_operations cache_flush_operations_pipefs = {
1831         .open           = open_flush_pipefs,
1832         .read           = read_flush_pipefs,
1833         .write          = write_flush_pipefs,
1834         .release        = release_flush_pipefs,
1835         .llseek         = no_llseek,
1836 };
1837 
1838 int sunrpc_cache_register_pipefs(struct dentry *parent,
1839                                  const char *name, umode_t umode,
1840                                  struct cache_detail *cd)
1841 {
1842         struct dentry *dir = rpc_create_cache_dir(parent, name, umode, cd);
1843         if (IS_ERR(dir))
1844                 return PTR_ERR(dir);
1845         cd->u.pipefs.dir = dir;
1846         return 0;
1847 }
1848 EXPORT_SYMBOL_GPL(sunrpc_cache_register_pipefs);
1849 
1850 void sunrpc_cache_unregister_pipefs(struct cache_detail *cd)
1851 {
1852         rpc_remove_cache_dir(cd->u.pipefs.dir);
1853         cd->u.pipefs.dir = NULL;
1854 }
1855 EXPORT_SYMBOL_GPL(sunrpc_cache_unregister_pipefs);
1856 
1857 

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