d5725cb1491eee9555074496b6d31dcae5144fa2
[linux-2.6.git] / net / sunrpc / cache.c
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 <asm/uaccess.h>
24 #include <linux/poll.h>
25 #include <linux/seq_file.h>
26 #include <linux/proc_fs.h>
27 #include <linux/net.h>
28 #include <linux/workqueue.h>
29 #include <linux/mutex.h>
30 #include <asm/ioctls.h>
31 #include <linux/sunrpc/types.h>
32 #include <linux/sunrpc/cache.h>
33 #include <linux/sunrpc/stats.h>
34
35 #define  RPCDBG_FACILITY RPCDBG_CACHE
36
37 static void cache_defer_req(struct cache_req *req, struct cache_head *item);
38 static void cache_revisit_request(struct cache_head *item);
39
40 static void cache_init(struct cache_head *h)
41 {
42         time_t now = get_seconds();
43         h->next = NULL;
44         h->flags = 0;
45         kref_init(&h->ref);
46         h->expiry_time = now + CACHE_NEW_EXPIRY;
47         h->last_refresh = now;
48 }
49
50 struct cache_head *sunrpc_cache_lookup(struct cache_detail *detail,
51                                        struct cache_head *key, int hash)
52 {
53         struct cache_head **head,  **hp;
54         struct cache_head *new = NULL;
55
56         head = &detail->hash_table[hash];
57
58         read_lock(&detail->hash_lock);
59
60         for (hp=head; *hp != NULL ; hp = &(*hp)->next) {
61                 struct cache_head *tmp = *hp;
62                 if (detail->match(tmp, key)) {
63                         cache_get(tmp);
64                         read_unlock(&detail->hash_lock);
65                         return tmp;
66                 }
67         }
68         read_unlock(&detail->hash_lock);
69         /* Didn't find anything, insert an empty entry */
70
71         new = detail->alloc();
72         if (!new)
73                 return NULL;
74         /* must fully initialise 'new', else
75          * we might get lose if we need to
76          * cache_put it soon.
77          */
78         cache_init(new);
79         detail->init(new, key);
80
81         write_lock(&detail->hash_lock);
82
83         /* check if entry appeared while we slept */
84         for (hp=head; *hp != NULL ; hp = &(*hp)->next) {
85                 struct cache_head *tmp = *hp;
86                 if (detail->match(tmp, key)) {
87                         cache_get(tmp);
88                         write_unlock(&detail->hash_lock);
89                         cache_put(new, detail);
90                         return tmp;
91                 }
92         }
93         new->next = *head;
94         *head = new;
95         detail->entries++;
96         cache_get(new);
97         write_unlock(&detail->hash_lock);
98
99         return new;
100 }
101 EXPORT_SYMBOL(sunrpc_cache_lookup);
102
103
104 static void queue_loose(struct cache_detail *detail, struct cache_head *ch);
105
106 static int cache_fresh_locked(struct cache_head *head, time_t expiry)
107 {
108         head->expiry_time = expiry;
109         head->last_refresh = get_seconds();
110         return !test_and_set_bit(CACHE_VALID, &head->flags);
111 }
112
113 static void cache_fresh_unlocked(struct cache_head *head,
114                         struct cache_detail *detail, int new)
115 {
116         if (new)
117                 cache_revisit_request(head);
118         if (test_and_clear_bit(CACHE_PENDING, &head->flags)) {
119                 cache_revisit_request(head);
120                 queue_loose(detail, head);
121         }
122 }
123
124 struct cache_head *sunrpc_cache_update(struct cache_detail *detail,
125                                        struct cache_head *new, struct cache_head *old, int hash)
126 {
127         /* The 'old' entry is to be replaced by 'new'.
128          * If 'old' is not VALID, we update it directly,
129          * otherwise we need to replace it
130          */
131         struct cache_head **head;
132         struct cache_head *tmp;
133         int is_new;
134
135         if (!test_bit(CACHE_VALID, &old->flags)) {
136                 write_lock(&detail->hash_lock);
137                 if (!test_bit(CACHE_VALID, &old->flags)) {
138                         if (test_bit(CACHE_NEGATIVE, &new->flags))
139                                 set_bit(CACHE_NEGATIVE, &old->flags);
140                         else
141                                 detail->update(old, new);
142                         is_new = cache_fresh_locked(old, new->expiry_time);
143                         write_unlock(&detail->hash_lock);
144                         cache_fresh_unlocked(old, detail, is_new);
145                         return old;
146                 }
147                 write_unlock(&detail->hash_lock);
148         }
149         /* We need to insert a new entry */
150         tmp = detail->alloc();
151         if (!tmp) {
152                 cache_put(old, detail);
153                 return NULL;
154         }
155         cache_init(tmp);
156         detail->init(tmp, old);
157         head = &detail->hash_table[hash];
158
159         write_lock(&detail->hash_lock);
160         if (test_bit(CACHE_NEGATIVE, &new->flags))
161                 set_bit(CACHE_NEGATIVE, &tmp->flags);
162         else
163                 detail->update(tmp, new);
164         tmp->next = *head;
165         *head = tmp;
166         detail->entries++;
167         cache_get(tmp);
168         is_new = cache_fresh_locked(tmp, new->expiry_time);
169         cache_fresh_locked(old, 0);
170         write_unlock(&detail->hash_lock);
171         cache_fresh_unlocked(tmp, detail, is_new);
172         cache_fresh_unlocked(old, detail, 0);
173         cache_put(old, detail);
174         return tmp;
175 }
176 EXPORT_SYMBOL(sunrpc_cache_update);
177
178 static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h);
179 /*
180  * This is the generic cache management routine for all
181  * the authentication caches.
182  * It checks the currency of a cache item and will (later)
183  * initiate an upcall to fill it if needed.
184  *
185  *
186  * Returns 0 if the cache_head can be used, or cache_puts it and returns
187  * -EAGAIN if upcall is pending,
188  * -ENOENT if cache entry was negative
189  */
190 int cache_check(struct cache_detail *detail,
191                     struct cache_head *h, struct cache_req *rqstp)
192 {
193         int rv;
194         long refresh_age, age;
195
196         /* First decide return status as best we can */
197         if (!test_bit(CACHE_VALID, &h->flags) ||
198             h->expiry_time < get_seconds())
199                 rv = -EAGAIN;
200         else if (detail->flush_time > h->last_refresh)
201                 rv = -EAGAIN;
202         else {
203                 /* entry is valid */
204                 if (test_bit(CACHE_NEGATIVE, &h->flags))
205                         rv = -ENOENT;
206                 else rv = 0;
207         }
208
209         /* now see if we want to start an upcall */
210         refresh_age = (h->expiry_time - h->last_refresh);
211         age = get_seconds() - h->last_refresh;
212
213         if (rqstp == NULL) {
214                 if (rv == -EAGAIN)
215                         rv = -ENOENT;
216         } else if (rv == -EAGAIN || age > refresh_age/2) {
217                 dprintk("Want update, refage=%ld, age=%ld\n", refresh_age, age);
218                 if (!test_and_set_bit(CACHE_PENDING, &h->flags)) {
219                         switch (cache_make_upcall(detail, h)) {
220                         case -EINVAL:
221                                 clear_bit(CACHE_PENDING, &h->flags);
222                                 if (rv == -EAGAIN) {
223                                         set_bit(CACHE_NEGATIVE, &h->flags);
224                                         cache_fresh_unlocked(h, detail,
225                                              cache_fresh_locked(h, get_seconds()+CACHE_NEW_EXPIRY));
226                                         rv = -ENOENT;
227                                 }
228                                 break;
229
230                         case -EAGAIN:
231                                 clear_bit(CACHE_PENDING, &h->flags);
232                                 cache_revisit_request(h);
233                                 break;
234                         }
235                 }
236         }
237
238         if (rv == -EAGAIN)
239                 cache_defer_req(rqstp, h);
240
241         if (rv)
242                 cache_put(h, detail);
243         return rv;
244 }
245
246 /*
247  * caches need to be periodically cleaned.
248  * For this we maintain a list of cache_detail and
249  * a current pointer into that list and into the table
250  * for that entry.
251  *
252  * Each time clean_cache is called it finds the next non-empty entry
253  * in the current table and walks the list in that entry
254  * looking for entries that can be removed.
255  *
256  * An entry gets removed if:
257  * - The expiry is before current time
258  * - The last_refresh time is before the flush_time for that cache
259  *
260  * later we might drop old entries with non-NEVER expiry if that table
261  * is getting 'full' for some definition of 'full'
262  *
263  * The question of "how often to scan a table" is an interesting one
264  * and is answered in part by the use of the "nextcheck" field in the
265  * cache_detail.
266  * When a scan of a table begins, the nextcheck field is set to a time
267  * that is well into the future.
268  * While scanning, if an expiry time is found that is earlier than the
269  * current nextcheck time, nextcheck is set to that expiry time.
270  * If the flush_time is ever set to a time earlier than the nextcheck
271  * time, the nextcheck time is then set to that flush_time.
272  *
273  * A table is then only scanned if the current time is at least
274  * the nextcheck time.
275  * 
276  */
277
278 static LIST_HEAD(cache_list);
279 static DEFINE_SPINLOCK(cache_list_lock);
280 static struct cache_detail *current_detail;
281 static int current_index;
282
283 static struct file_operations cache_file_operations;
284 static struct file_operations content_file_operations;
285 static struct file_operations cache_flush_operations;
286
287 static void do_cache_clean(void *data);
288 static DECLARE_DELAYED_WORK(cache_cleaner, do_cache_clean, NULL);
289
290 void cache_register(struct cache_detail *cd)
291 {
292         cd->proc_ent = proc_mkdir(cd->name, proc_net_rpc);
293         if (cd->proc_ent) {
294                 struct proc_dir_entry *p;
295                 cd->proc_ent->owner = cd->owner;
296                 cd->channel_ent = cd->content_ent = NULL;
297                 
298                 p = create_proc_entry("flush", S_IFREG|S_IRUSR|S_IWUSR,
299                                       cd->proc_ent);
300                 cd->flush_ent =  p;
301                 if (p) {
302                         p->proc_fops = &cache_flush_operations;
303                         p->owner = cd->owner;
304                         p->data = cd;
305                 }
306  
307                 if (cd->cache_request || cd->cache_parse) {
308                         p = create_proc_entry("channel", S_IFREG|S_IRUSR|S_IWUSR,
309                                               cd->proc_ent);
310                         cd->channel_ent = p;
311                         if (p) {
312                                 p->proc_fops = &cache_file_operations;
313                                 p->owner = cd->owner;
314                                 p->data = cd;
315                         }
316                 }
317                 if (cd->cache_show) {
318                         p = create_proc_entry("content", S_IFREG|S_IRUSR|S_IWUSR,
319                                               cd->proc_ent);
320                         cd->content_ent = p;
321                         if (p) {
322                                 p->proc_fops = &content_file_operations;
323                                 p->owner = cd->owner;
324                                 p->data = cd;
325                         }
326                 }
327         }
328         rwlock_init(&cd->hash_lock);
329         INIT_LIST_HEAD(&cd->queue);
330         spin_lock(&cache_list_lock);
331         cd->nextcheck = 0;
332         cd->entries = 0;
333         atomic_set(&cd->readers, 0);
334         cd->last_close = 0;
335         cd->last_warn = -1;
336         list_add(&cd->others, &cache_list);
337         spin_unlock(&cache_list_lock);
338
339         /* start the cleaning process */
340         schedule_delayed_work(&cache_cleaner, 0);
341 }
342
343 int cache_unregister(struct cache_detail *cd)
344 {
345         cache_purge(cd);
346         spin_lock(&cache_list_lock);
347         write_lock(&cd->hash_lock);
348         if (cd->entries || atomic_read(&cd->inuse)) {
349                 write_unlock(&cd->hash_lock);
350                 spin_unlock(&cache_list_lock);
351                 return -EBUSY;
352         }
353         if (current_detail == cd)
354                 current_detail = NULL;
355         list_del_init(&cd->others);
356         write_unlock(&cd->hash_lock);
357         spin_unlock(&cache_list_lock);
358         if (cd->proc_ent) {
359                 if (cd->flush_ent)
360                         remove_proc_entry("flush", cd->proc_ent);
361                 if (cd->channel_ent)
362                         remove_proc_entry("channel", cd->proc_ent);
363                 if (cd->content_ent)
364                         remove_proc_entry("content", cd->proc_ent);
365
366                 cd->proc_ent = NULL;
367                 remove_proc_entry(cd->name, proc_net_rpc);
368         }
369         if (list_empty(&cache_list)) {
370                 /* module must be being unloaded so its safe to kill the worker */
371                 cancel_delayed_work(&cache_cleaner);
372                 flush_scheduled_work();
373         }
374         return 0;
375 }
376
377 /* clean cache tries to find something to clean
378  * and cleans it.
379  * It returns 1 if it cleaned something,
380  *            0 if it didn't find anything this time
381  *           -1 if it fell off the end of the list.
382  */
383 static int cache_clean(void)
384 {
385         int rv = 0;
386         struct list_head *next;
387
388         spin_lock(&cache_list_lock);
389
390         /* find a suitable table if we don't already have one */
391         while (current_detail == NULL ||
392             current_index >= current_detail->hash_size) {
393                 if (current_detail)
394                         next = current_detail->others.next;
395                 else
396                         next = cache_list.next;
397                 if (next == &cache_list) {
398                         current_detail = NULL;
399                         spin_unlock(&cache_list_lock);
400                         return -1;
401                 }
402                 current_detail = list_entry(next, struct cache_detail, others);
403                 if (current_detail->nextcheck > get_seconds())
404                         current_index = current_detail->hash_size;
405                 else {
406                         current_index = 0;
407                         current_detail->nextcheck = get_seconds()+30*60;
408                 }
409         }
410
411         /* find a non-empty bucket in the table */
412         while (current_detail &&
413                current_index < current_detail->hash_size &&
414                current_detail->hash_table[current_index] == NULL)
415                 current_index++;
416
417         /* find a cleanable entry in the bucket and clean it, or set to next bucket */
418         
419         if (current_detail && current_index < current_detail->hash_size) {
420                 struct cache_head *ch, **cp;
421                 struct cache_detail *d;
422                 
423                 write_lock(&current_detail->hash_lock);
424
425                 /* Ok, now to clean this strand */
426                         
427                 cp = & current_detail->hash_table[current_index];
428                 ch = *cp;
429                 for (; ch; cp= & ch->next, ch= *cp) {
430                         if (current_detail->nextcheck > ch->expiry_time)
431                                 current_detail->nextcheck = ch->expiry_time+1;
432                         if (ch->expiry_time >= get_seconds()
433                             && ch->last_refresh >= current_detail->flush_time
434                                 )
435                                 continue;
436                         if (test_and_clear_bit(CACHE_PENDING, &ch->flags))
437                                 queue_loose(current_detail, ch);
438
439                         if (atomic_read(&ch->ref.refcount) == 1)
440                                 break;
441                 }
442                 if (ch) {
443                         *cp = ch->next;
444                         ch->next = NULL;
445                         current_detail->entries--;
446                         rv = 1;
447                 }
448                 write_unlock(&current_detail->hash_lock);
449                 d = current_detail;
450                 if (!ch)
451                         current_index ++;
452                 spin_unlock(&cache_list_lock);
453                 if (ch)
454                         cache_put(ch, d);
455         } else
456                 spin_unlock(&cache_list_lock);
457
458         return rv;
459 }
460
461 /*
462  * We want to regularly clean the cache, so we need to schedule some work ...
463  */
464 static void do_cache_clean(void *data)
465 {
466         int delay = 5;
467         if (cache_clean() == -1)
468                 delay = 30*HZ;
469
470         if (list_empty(&cache_list))
471                 delay = 0;
472
473         if (delay)
474                 schedule_delayed_work(&cache_cleaner, delay);
475 }
476
477
478 /* 
479  * Clean all caches promptly.  This just calls cache_clean
480  * repeatedly until we are sure that every cache has had a chance to 
481  * be fully cleaned
482  */
483 void cache_flush(void)
484 {
485         while (cache_clean() != -1)
486                 cond_resched();
487         while (cache_clean() != -1)
488                 cond_resched();
489 }
490
491 void cache_purge(struct cache_detail *detail)
492 {
493         detail->flush_time = LONG_MAX;
494         detail->nextcheck = get_seconds();
495         cache_flush();
496         detail->flush_time = 1;
497 }
498
499
500
501 /*
502  * Deferral and Revisiting of Requests.
503  *
504  * If a cache lookup finds a pending entry, we
505  * need to defer the request and revisit it later.
506  * All deferred requests are stored in a hash table,
507  * indexed by "struct cache_head *".
508  * As it may be wasteful to store a whole request
509  * structure, we allow the request to provide a 
510  * deferred form, which must contain a
511  * 'struct cache_deferred_req'
512  * This cache_deferred_req contains a method to allow
513  * it to be revisited when cache info is available
514  */
515
516 #define DFR_HASHSIZE    (PAGE_SIZE/sizeof(struct list_head))
517 #define DFR_HASH(item)  ((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE)
518
519 #define DFR_MAX 300     /* ??? */
520
521 static DEFINE_SPINLOCK(cache_defer_lock);
522 static LIST_HEAD(cache_defer_list);
523 static struct list_head cache_defer_hash[DFR_HASHSIZE];
524 static int cache_defer_cnt;
525
526 static void cache_defer_req(struct cache_req *req, struct cache_head *item)
527 {
528         struct cache_deferred_req *dreq;
529         int hash = DFR_HASH(item);
530
531         dreq = req->defer(req);
532         if (dreq == NULL)
533                 return;
534
535         dreq->item = item;
536         dreq->recv_time = get_seconds();
537
538         spin_lock(&cache_defer_lock);
539
540         list_add(&dreq->recent, &cache_defer_list);
541
542         if (cache_defer_hash[hash].next == NULL)
543                 INIT_LIST_HEAD(&cache_defer_hash[hash]);
544         list_add(&dreq->hash, &cache_defer_hash[hash]);
545
546         /* it is in, now maybe clean up */
547         dreq = NULL;
548         if (++cache_defer_cnt > DFR_MAX) {
549                 /* too much in the cache, randomly drop
550                  * first or last
551                  */
552                 if (net_random()&1) 
553                         dreq = list_entry(cache_defer_list.next,
554                                           struct cache_deferred_req,
555                                           recent);
556                 else
557                         dreq = list_entry(cache_defer_list.prev,
558                                           struct cache_deferred_req,
559                                           recent);
560                 list_del(&dreq->recent);
561                 list_del(&dreq->hash);
562                 cache_defer_cnt--;
563         }
564         spin_unlock(&cache_defer_lock);
565
566         if (dreq) {
567                 /* there was one too many */
568                 dreq->revisit(dreq, 1);
569         }
570         if (!test_bit(CACHE_PENDING, &item->flags)) {
571                 /* must have just been validated... */
572                 cache_revisit_request(item);
573         }
574 }
575
576 static void cache_revisit_request(struct cache_head *item)
577 {
578         struct cache_deferred_req *dreq;
579         struct list_head pending;
580
581         struct list_head *lp;
582         int hash = DFR_HASH(item);
583
584         INIT_LIST_HEAD(&pending);
585         spin_lock(&cache_defer_lock);
586         
587         lp = cache_defer_hash[hash].next;
588         if (lp) {
589                 while (lp != &cache_defer_hash[hash]) {
590                         dreq = list_entry(lp, struct cache_deferred_req, hash);
591                         lp = lp->next;
592                         if (dreq->item == item) {
593                                 list_del(&dreq->hash);
594                                 list_move(&dreq->recent, &pending);
595                                 cache_defer_cnt--;
596                         }
597                 }
598         }
599         spin_unlock(&cache_defer_lock);
600
601         while (!list_empty(&pending)) {
602                 dreq = list_entry(pending.next, struct cache_deferred_req, recent);
603                 list_del_init(&dreq->recent);
604                 dreq->revisit(dreq, 0);
605         }
606 }
607
608 void cache_clean_deferred(void *owner)
609 {
610         struct cache_deferred_req *dreq, *tmp;
611         struct list_head pending;
612
613
614         INIT_LIST_HEAD(&pending);
615         spin_lock(&cache_defer_lock);
616         
617         list_for_each_entry_safe(dreq, tmp, &cache_defer_list, recent) {
618                 if (dreq->owner == owner) {
619                         list_del(&dreq->hash);
620                         list_move(&dreq->recent, &pending);
621                         cache_defer_cnt--;
622                 }
623         }
624         spin_unlock(&cache_defer_lock);
625
626         while (!list_empty(&pending)) {
627                 dreq = list_entry(pending.next, struct cache_deferred_req, recent);
628                 list_del_init(&dreq->recent);
629                 dreq->revisit(dreq, 1);
630         }
631 }
632
633 /*
634  * communicate with user-space
635  *
636  * We have a magic /proc file - /proc/sunrpc/cache
637  * On read, you get a full request, or block
638  * On write, an update request is processed
639  * Poll works if anything to read, and always allows write
640  *
641  * Implemented by linked list of requests.  Each open file has 
642  * a ->private that also exists in this list.  New request are added
643  * to the end and may wakeup and preceding readers.
644  * New readers are added to the head.  If, on read, an item is found with
645  * CACHE_UPCALLING clear, we free it from the list.
646  *
647  */
648
649 static DEFINE_SPINLOCK(queue_lock);
650 static DEFINE_MUTEX(queue_io_mutex);
651
652 struct cache_queue {
653         struct list_head        list;
654         int                     reader; /* if 0, then request */
655 };
656 struct cache_request {
657         struct cache_queue      q;
658         struct cache_head       *item;
659         char                    * buf;
660         int                     len;
661         int                     readers;
662 };
663 struct cache_reader {
664         struct cache_queue      q;
665         int                     offset; /* if non-0, we have a refcnt on next request */
666 };
667
668 static ssize_t
669 cache_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
670 {
671         struct cache_reader *rp = filp->private_data;
672         struct cache_request *rq;
673         struct cache_detail *cd = PDE(filp->f_dentry->d_inode)->data;
674         int err;
675
676         if (count == 0)
677                 return 0;
678
679         mutex_lock(&queue_io_mutex); /* protect against multiple concurrent
680                               * readers on this file */
681  again:
682         spin_lock(&queue_lock);
683         /* need to find next request */
684         while (rp->q.list.next != &cd->queue &&
685                list_entry(rp->q.list.next, struct cache_queue, list)
686                ->reader) {
687                 struct list_head *next = rp->q.list.next;
688                 list_move(&rp->q.list, next);
689         }
690         if (rp->q.list.next == &cd->queue) {
691                 spin_unlock(&queue_lock);
692                 mutex_unlock(&queue_io_mutex);
693                 BUG_ON(rp->offset);
694                 return 0;
695         }
696         rq = container_of(rp->q.list.next, struct cache_request, q.list);
697         BUG_ON(rq->q.reader);
698         if (rp->offset == 0)
699                 rq->readers++;
700         spin_unlock(&queue_lock);
701
702         if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) {
703                 err = -EAGAIN;
704                 spin_lock(&queue_lock);
705                 list_move(&rp->q.list, &rq->q.list);
706                 spin_unlock(&queue_lock);
707         } else {
708                 if (rp->offset + count > rq->len)
709                         count = rq->len - rp->offset;
710                 err = -EFAULT;
711                 if (copy_to_user(buf, rq->buf + rp->offset, count))
712                         goto out;
713                 rp->offset += count;
714                 if (rp->offset >= rq->len) {
715                         rp->offset = 0;
716                         spin_lock(&queue_lock);
717                         list_move(&rp->q.list, &rq->q.list);
718                         spin_unlock(&queue_lock);
719                 }
720                 err = 0;
721         }
722  out:
723         if (rp->offset == 0) {
724                 /* need to release rq */
725                 spin_lock(&queue_lock);
726                 rq->readers--;
727                 if (rq->readers == 0 &&
728                     !test_bit(CACHE_PENDING, &rq->item->flags)) {
729                         list_del(&rq->q.list);
730                         spin_unlock(&queue_lock);
731                         cache_put(rq->item, cd);
732                         kfree(rq->buf);
733                         kfree(rq);
734                 } else
735                         spin_unlock(&queue_lock);
736         }
737         if (err == -EAGAIN)
738                 goto again;
739         mutex_unlock(&queue_io_mutex);
740         return err ? err :  count;
741 }
742
743 static char write_buf[8192]; /* protected by queue_io_mutex */
744
745 static ssize_t
746 cache_write(struct file *filp, const char __user *buf, size_t count,
747             loff_t *ppos)
748 {
749         int err;
750         struct cache_detail *cd = PDE(filp->f_dentry->d_inode)->data;
751
752         if (count == 0)
753                 return 0;
754         if (count >= sizeof(write_buf))
755                 return -EINVAL;
756
757         mutex_lock(&queue_io_mutex);
758
759         if (copy_from_user(write_buf, buf, count)) {
760                 mutex_unlock(&queue_io_mutex);
761                 return -EFAULT;
762         }
763         write_buf[count] = '\0';
764         if (cd->cache_parse)
765                 err = cd->cache_parse(cd, write_buf, count);
766         else
767                 err = -EINVAL;
768
769         mutex_unlock(&queue_io_mutex);
770         return err ? err : count;
771 }
772
773 static DECLARE_WAIT_QUEUE_HEAD(queue_wait);
774
775 static unsigned int
776 cache_poll(struct file *filp, poll_table *wait)
777 {
778         unsigned int mask;
779         struct cache_reader *rp = filp->private_data;
780         struct cache_queue *cq;
781         struct cache_detail *cd = PDE(filp->f_dentry->d_inode)->data;
782
783         poll_wait(filp, &queue_wait, wait);
784
785         /* alway allow write */
786         mask = POLL_OUT | POLLWRNORM;
787
788         if (!rp)
789                 return mask;
790
791         spin_lock(&queue_lock);
792
793         for (cq= &rp->q; &cq->list != &cd->queue;
794              cq = list_entry(cq->list.next, struct cache_queue, list))
795                 if (!cq->reader) {
796                         mask |= POLLIN | POLLRDNORM;
797                         break;
798                 }
799         spin_unlock(&queue_lock);
800         return mask;
801 }
802
803 static int
804 cache_ioctl(struct inode *ino, struct file *filp,
805             unsigned int cmd, unsigned long arg)
806 {
807         int len = 0;
808         struct cache_reader *rp = filp->private_data;
809         struct cache_queue *cq;
810         struct cache_detail *cd = PDE(ino)->data;
811
812         if (cmd != FIONREAD || !rp)
813                 return -EINVAL;
814
815         spin_lock(&queue_lock);
816
817         /* only find the length remaining in current request,
818          * or the length of the next request
819          */
820         for (cq= &rp->q; &cq->list != &cd->queue;
821              cq = list_entry(cq->list.next, struct cache_queue, list))
822                 if (!cq->reader) {
823                         struct cache_request *cr =
824                                 container_of(cq, struct cache_request, q);
825                         len = cr->len - rp->offset;
826                         break;
827                 }
828         spin_unlock(&queue_lock);
829
830         return put_user(len, (int __user *)arg);
831 }
832
833 static int
834 cache_open(struct inode *inode, struct file *filp)
835 {
836         struct cache_reader *rp = NULL;
837
838         nonseekable_open(inode, filp);
839         if (filp->f_mode & FMODE_READ) {
840                 struct cache_detail *cd = PDE(inode)->data;
841
842                 rp = kmalloc(sizeof(*rp), GFP_KERNEL);
843                 if (!rp)
844                         return -ENOMEM;
845                 rp->offset = 0;
846                 rp->q.reader = 1;
847                 atomic_inc(&cd->readers);
848                 spin_lock(&queue_lock);
849                 list_add(&rp->q.list, &cd->queue);
850                 spin_unlock(&queue_lock);
851         }
852         filp->private_data = rp;
853         return 0;
854 }
855
856 static int
857 cache_release(struct inode *inode, struct file *filp)
858 {
859         struct cache_reader *rp = filp->private_data;
860         struct cache_detail *cd = PDE(inode)->data;
861
862         if (rp) {
863                 spin_lock(&queue_lock);
864                 if (rp->offset) {
865                         struct cache_queue *cq;
866                         for (cq= &rp->q; &cq->list != &cd->queue;
867                              cq = list_entry(cq->list.next, struct cache_queue, list))
868                                 if (!cq->reader) {
869                                         container_of(cq, struct cache_request, q)
870                                                 ->readers--;
871                                         break;
872                                 }
873                         rp->offset = 0;
874                 }
875                 list_del(&rp->q.list);
876                 spin_unlock(&queue_lock);
877
878                 filp->private_data = NULL;
879                 kfree(rp);
880
881                 cd->last_close = get_seconds();
882                 atomic_dec(&cd->readers);
883         }
884         return 0;
885 }
886
887
888
889 static struct file_operations cache_file_operations = {
890         .owner          = THIS_MODULE,
891         .llseek         = no_llseek,
892         .read           = cache_read,
893         .write          = cache_write,
894         .poll           = cache_poll,
895         .ioctl          = cache_ioctl, /* for FIONREAD */
896         .open           = cache_open,
897         .release        = cache_release,
898 };
899
900
901 static void queue_loose(struct cache_detail *detail, struct cache_head *ch)
902 {
903         struct cache_queue *cq;
904         spin_lock(&queue_lock);
905         list_for_each_entry(cq, &detail->queue, list)
906                 if (!cq->reader) {
907                         struct cache_request *cr = container_of(cq, struct cache_request, q);
908                         if (cr->item != ch)
909                                 continue;
910                         if (cr->readers != 0)
911                                 continue;
912                         list_del(&cr->q.list);
913                         spin_unlock(&queue_lock);
914                         cache_put(cr->item, detail);
915                         kfree(cr->buf);
916                         kfree(cr);
917                         return;
918                 }
919         spin_unlock(&queue_lock);
920 }
921
922 /*
923  * Support routines for text-based upcalls.
924  * Fields are separated by spaces.
925  * Fields are either mangled to quote space tab newline slosh with slosh
926  * or a hexified with a leading \x
927  * Record is terminated with newline.
928  *
929  */
930
931 void qword_add(char **bpp, int *lp, char *str)
932 {
933         char *bp = *bpp;
934         int len = *lp;
935         char c;
936
937         if (len < 0) return;
938
939         while ((c=*str++) && len)
940                 switch(c) {
941                 case ' ':
942                 case '\t':
943                 case '\n':
944                 case '\\':
945                         if (len >= 4) {
946                                 *bp++ = '\\';
947                                 *bp++ = '0' + ((c & 0300)>>6);
948                                 *bp++ = '0' + ((c & 0070)>>3);
949                                 *bp++ = '0' + ((c & 0007)>>0);
950                         }
951                         len -= 4;
952                         break;
953                 default:
954                         *bp++ = c;
955                         len--;
956                 }
957         if (c || len <1) len = -1;
958         else {
959                 *bp++ = ' ';
960                 len--;
961         }
962         *bpp = bp;
963         *lp = len;
964 }
965
966 void qword_addhex(char **bpp, int *lp, char *buf, int blen)
967 {
968         char *bp = *bpp;
969         int len = *lp;
970
971         if (len < 0) return;
972
973         if (len > 2) {
974                 *bp++ = '\\';
975                 *bp++ = 'x';
976                 len -= 2;
977                 while (blen && len >= 2) {
978                         unsigned char c = *buf++;
979                         *bp++ = '0' + ((c&0xf0)>>4) + (c>=0xa0)*('a'-'9'-1);
980                         *bp++ = '0' + (c&0x0f) + ((c&0x0f)>=0x0a)*('a'-'9'-1);
981                         len -= 2;
982                         blen--;
983                 }
984         }
985         if (blen || len<1) len = -1;
986         else {
987                 *bp++ = ' ';
988                 len--;
989         }
990         *bpp = bp;
991         *lp = len;
992 }
993
994 static void warn_no_listener(struct cache_detail *detail)
995 {
996         if (detail->last_warn != detail->last_close) {
997                 detail->last_warn = detail->last_close;
998                 if (detail->warn_no_listener)
999                         detail->warn_no_listener(detail);
1000         }
1001 }
1002
1003 /*
1004  * register an upcall request to user-space.
1005  * Each request is at most one page long.
1006  */
1007 static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h)
1008 {
1009
1010         char *buf;
1011         struct cache_request *crq;
1012         char *bp;
1013         int len;
1014
1015         if (detail->cache_request == NULL)
1016                 return -EINVAL;
1017
1018         if (atomic_read(&detail->readers) == 0 &&
1019             detail->last_close < get_seconds() - 30) {
1020                         warn_no_listener(detail);
1021                         return -EINVAL;
1022         }
1023
1024         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
1025         if (!buf)
1026                 return -EAGAIN;
1027
1028         crq = kmalloc(sizeof (*crq), GFP_KERNEL);
1029         if (!crq) {
1030                 kfree(buf);
1031                 return -EAGAIN;
1032         }
1033
1034         bp = buf; len = PAGE_SIZE;
1035
1036         detail->cache_request(detail, h, &bp, &len);
1037
1038         if (len < 0) {
1039                 kfree(buf);
1040                 kfree(crq);
1041                 return -EAGAIN;
1042         }
1043         crq->q.reader = 0;
1044         crq->item = cache_get(h);
1045         crq->buf = buf;
1046         crq->len = PAGE_SIZE - len;
1047         crq->readers = 0;
1048         spin_lock(&queue_lock);
1049         list_add_tail(&crq->q.list, &detail->queue);
1050         spin_unlock(&queue_lock);
1051         wake_up(&queue_wait);
1052         return 0;
1053 }
1054
1055 /*
1056  * parse a message from user-space and pass it
1057  * to an appropriate cache
1058  * Messages are, like requests, separated into fields by
1059  * spaces and dequotes as \xHEXSTRING or embedded \nnn octal
1060  *
1061  * Message is 
1062  *   reply cachename expiry key ... content....
1063  *
1064  * key and content are both parsed by cache 
1065  */
1066
1067 #define isodigit(c) (isdigit(c) && c <= '7')
1068 int qword_get(char **bpp, char *dest, int bufsize)
1069 {
1070         /* return bytes copied, or -1 on error */
1071         char *bp = *bpp;
1072         int len = 0;
1073
1074         while (*bp == ' ') bp++;
1075
1076         if (bp[0] == '\\' && bp[1] == 'x') {
1077                 /* HEX STRING */
1078                 bp += 2;
1079                 while (isxdigit(bp[0]) && isxdigit(bp[1]) && len < bufsize) {
1080                         int byte = isdigit(*bp) ? *bp-'0' : toupper(*bp)-'A'+10;
1081                         bp++;
1082                         byte <<= 4;
1083                         byte |= isdigit(*bp) ? *bp-'0' : toupper(*bp)-'A'+10;
1084                         *dest++ = byte;
1085                         bp++;
1086                         len++;
1087                 }
1088         } else {
1089                 /* text with \nnn octal quoting */
1090                 while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) {
1091                         if (*bp == '\\' &&
1092                             isodigit(bp[1]) && (bp[1] <= '3') &&
1093                             isodigit(bp[2]) &&
1094                             isodigit(bp[3])) {
1095                                 int byte = (*++bp -'0');
1096                                 bp++;
1097                                 byte = (byte << 3) | (*bp++ - '0');
1098                                 byte = (byte << 3) | (*bp++ - '0');
1099                                 *dest++ = byte;
1100                                 len++;
1101                         } else {
1102                                 *dest++ = *bp++;
1103                                 len++;
1104                         }
1105                 }
1106         }
1107
1108         if (*bp != ' ' && *bp != '\n' && *bp != '\0')
1109                 return -1;
1110         while (*bp == ' ') bp++;
1111         *bpp = bp;
1112         *dest = '\0';
1113         return len;
1114 }
1115
1116
1117 /*
1118  * support /proc/sunrpc/cache/$CACHENAME/content
1119  * as a seqfile.
1120  * We call ->cache_show passing NULL for the item to
1121  * get a header, then pass each real item in the cache
1122  */
1123
1124 struct handle {
1125         struct cache_detail *cd;
1126 };
1127
1128 static void *c_start(struct seq_file *m, loff_t *pos)
1129 {
1130         loff_t n = *pos;
1131         unsigned hash, entry;
1132         struct cache_head *ch;
1133         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1134         
1135
1136         read_lock(&cd->hash_lock);
1137         if (!n--)
1138                 return SEQ_START_TOKEN;
1139         hash = n >> 32;
1140         entry = n & ((1LL<<32) - 1);
1141
1142         for (ch=cd->hash_table[hash]; ch; ch=ch->next)
1143                 if (!entry--)
1144                         return ch;
1145         n &= ~((1LL<<32) - 1);
1146         do {
1147                 hash++;
1148                 n += 1LL<<32;
1149         } while(hash < cd->hash_size && 
1150                 cd->hash_table[hash]==NULL);
1151         if (hash >= cd->hash_size)
1152                 return NULL;
1153         *pos = n+1;
1154         return cd->hash_table[hash];
1155 }
1156
1157 static void *c_next(struct seq_file *m, void *p, loff_t *pos)
1158 {
1159         struct cache_head *ch = p;
1160         int hash = (*pos >> 32);
1161         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1162
1163         if (p == SEQ_START_TOKEN)
1164                 hash = 0;
1165         else if (ch->next == NULL) {
1166                 hash++;
1167                 *pos += 1LL<<32;
1168         } else {
1169                 ++*pos;
1170                 return ch->next;
1171         }
1172         *pos &= ~((1LL<<32) - 1);
1173         while (hash < cd->hash_size &&
1174                cd->hash_table[hash] == NULL) {
1175                 hash++;
1176                 *pos += 1LL<<32;
1177         }
1178         if (hash >= cd->hash_size)
1179                 return NULL;
1180         ++*pos;
1181         return cd->hash_table[hash];
1182 }
1183
1184 static void c_stop(struct seq_file *m, void *p)
1185 {
1186         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1187         read_unlock(&cd->hash_lock);
1188 }
1189
1190 static int c_show(struct seq_file *m, void *p)
1191 {
1192         struct cache_head *cp = p;
1193         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1194
1195         if (p == SEQ_START_TOKEN)
1196                 return cd->cache_show(m, cd, NULL);
1197
1198         ifdebug(CACHE)
1199                 seq_printf(m, "# expiry=%ld refcnt=%d flags=%lx\n",
1200                            cp->expiry_time, atomic_read(&cp->ref.refcount), cp->flags);
1201         cache_get(cp);
1202         if (cache_check(cd, cp, NULL))
1203                 /* cache_check does a cache_put on failure */
1204                 seq_printf(m, "# ");
1205         else
1206                 cache_put(cp, cd);
1207
1208         return cd->cache_show(m, cd, cp);
1209 }
1210
1211 static struct seq_operations cache_content_op = {
1212         .start  = c_start,
1213         .next   = c_next,
1214         .stop   = c_stop,
1215         .show   = c_show,
1216 };
1217
1218 static int content_open(struct inode *inode, struct file *file)
1219 {
1220         int res;
1221         struct handle *han;
1222         struct cache_detail *cd = PDE(inode)->data;
1223
1224         han = kmalloc(sizeof(*han), GFP_KERNEL);
1225         if (han == NULL)
1226                 return -ENOMEM;
1227
1228         han->cd = cd;
1229
1230         res = seq_open(file, &cache_content_op);
1231         if (res)
1232                 kfree(han);
1233         else
1234                 ((struct seq_file *)file->private_data)->private = han;
1235
1236         return res;
1237 }
1238 static int content_release(struct inode *inode, struct file *file)
1239 {
1240         struct seq_file *m = (struct seq_file *)file->private_data;
1241         struct handle *han = m->private;
1242         kfree(han);
1243         m->private = NULL;
1244         return seq_release(inode, file);
1245 }
1246
1247 static struct file_operations content_file_operations = {
1248         .open           = content_open,
1249         .read           = seq_read,
1250         .llseek         = seq_lseek,
1251         .release        = content_release,
1252 };
1253
1254 static ssize_t read_flush(struct file *file, char __user *buf,
1255                             size_t count, loff_t *ppos)
1256 {
1257         struct cache_detail *cd = PDE(file->f_dentry->d_inode)->data;
1258         char tbuf[20];
1259         unsigned long p = *ppos;
1260         int len;
1261
1262         sprintf(tbuf, "%lu\n", cd->flush_time);
1263         len = strlen(tbuf);
1264         if (p >= len)
1265                 return 0;
1266         len -= p;
1267         if (len > count) len = count;
1268         if (copy_to_user(buf, (void*)(tbuf+p), len))
1269                 len = -EFAULT;
1270         else
1271                 *ppos += len;
1272         return len;
1273 }
1274
1275 static ssize_t write_flush(struct file * file, const char __user * buf,
1276                              size_t count, loff_t *ppos)
1277 {
1278         struct cache_detail *cd = PDE(file->f_dentry->d_inode)->data;
1279         char tbuf[20];
1280         char *ep;
1281         long flushtime;
1282         if (*ppos || count > sizeof(tbuf)-1)
1283                 return -EINVAL;
1284         if (copy_from_user(tbuf, buf, count))
1285                 return -EFAULT;
1286         tbuf[count] = 0;
1287         flushtime = simple_strtoul(tbuf, &ep, 0);
1288         if (*ep && *ep != '\n')
1289                 return -EINVAL;
1290
1291         cd->flush_time = flushtime;
1292         cd->nextcheck = get_seconds();
1293         cache_flush();
1294
1295         *ppos += count;
1296         return count;
1297 }
1298
1299 static struct file_operations cache_flush_operations = {
1300         .open           = nonseekable_open,
1301         .read           = read_flush,
1302         .write          = write_flush,
1303 };