Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/shaggy...
[linux-2.6] / 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 int 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  * -ETIMEDOUT if upcall failed and should be retried,
189  * -ENOENT if cache entry was negative
190  */
191 int cache_check(struct cache_detail *detail,
192                     struct cache_head *h, struct cache_req *rqstp)
193 {
194         int rv;
195         long refresh_age, age;
196
197         /* First decide return status as best we can */
198         if (!test_bit(CACHE_VALID, &h->flags) ||
199             h->expiry_time < get_seconds())
200                 rv = -EAGAIN;
201         else if (detail->flush_time > h->last_refresh)
202                 rv = -EAGAIN;
203         else {
204                 /* entry is valid */
205                 if (test_bit(CACHE_NEGATIVE, &h->flags))
206                         rv = -ENOENT;
207                 else rv = 0;
208         }
209
210         /* now see if we want to start an upcall */
211         refresh_age = (h->expiry_time - h->last_refresh);
212         age = get_seconds() - h->last_refresh;
213
214         if (rqstp == NULL) {
215                 if (rv == -EAGAIN)
216                         rv = -ENOENT;
217         } else if (rv == -EAGAIN || age > refresh_age/2) {
218                 dprintk("RPC:       Want update, refage=%ld, age=%ld\n",
219                                 refresh_age, age);
220                 if (!test_and_set_bit(CACHE_PENDING, &h->flags)) {
221                         switch (cache_make_upcall(detail, h)) {
222                         case -EINVAL:
223                                 clear_bit(CACHE_PENDING, &h->flags);
224                                 if (rv == -EAGAIN) {
225                                         set_bit(CACHE_NEGATIVE, &h->flags);
226                                         cache_fresh_unlocked(h, detail,
227                                              cache_fresh_locked(h, get_seconds()+CACHE_NEW_EXPIRY));
228                                         rv = -ENOENT;
229                                 }
230                                 break;
231
232                         case -EAGAIN:
233                                 clear_bit(CACHE_PENDING, &h->flags);
234                                 cache_revisit_request(h);
235                                 break;
236                         }
237                 }
238         }
239
240         if (rv == -EAGAIN)
241                 if (cache_defer_req(rqstp, h) != 0)
242                         rv = -ETIMEDOUT;
243
244         if (rv)
245                 cache_put(h, detail);
246         return rv;
247 }
248
249 /*
250  * caches need to be periodically cleaned.
251  * For this we maintain a list of cache_detail and
252  * a current pointer into that list and into the table
253  * for that entry.
254  *
255  * Each time clean_cache is called it finds the next non-empty entry
256  * in the current table and walks the list in that entry
257  * looking for entries that can be removed.
258  *
259  * An entry gets removed if:
260  * - The expiry is before current time
261  * - The last_refresh time is before the flush_time for that cache
262  *
263  * later we might drop old entries with non-NEVER expiry if that table
264  * is getting 'full' for some definition of 'full'
265  *
266  * The question of "how often to scan a table" is an interesting one
267  * and is answered in part by the use of the "nextcheck" field in the
268  * cache_detail.
269  * When a scan of a table begins, the nextcheck field is set to a time
270  * that is well into the future.
271  * While scanning, if an expiry time is found that is earlier than the
272  * current nextcheck time, nextcheck is set to that expiry time.
273  * If the flush_time is ever set to a time earlier than the nextcheck
274  * time, the nextcheck time is then set to that flush_time.
275  *
276  * A table is then only scanned if the current time is at least
277  * the nextcheck time.
278  *
279  */
280
281 static LIST_HEAD(cache_list);
282 static DEFINE_SPINLOCK(cache_list_lock);
283 static struct cache_detail *current_detail;
284 static int current_index;
285
286 static const struct file_operations cache_file_operations;
287 static const struct file_operations content_file_operations;
288 static const struct file_operations cache_flush_operations;
289
290 static void do_cache_clean(struct work_struct *work);
291 static DECLARE_DELAYED_WORK(cache_cleaner, do_cache_clean);
292
293 void cache_register(struct cache_detail *cd)
294 {
295         cd->proc_ent = proc_mkdir(cd->name, proc_net_rpc);
296         if (cd->proc_ent) {
297                 struct proc_dir_entry *p;
298                 cd->proc_ent->owner = cd->owner;
299                 cd->channel_ent = cd->content_ent = NULL;
300
301                 p = create_proc_entry("flush", S_IFREG|S_IRUSR|S_IWUSR,
302                                       cd->proc_ent);
303                 cd->flush_ent =  p;
304                 if (p) {
305                         p->proc_fops = &cache_flush_operations;
306                         p->owner = cd->owner;
307                         p->data = cd;
308                 }
309
310                 if (cd->cache_request || cd->cache_parse) {
311                         p = create_proc_entry("channel", S_IFREG|S_IRUSR|S_IWUSR,
312                                               cd->proc_ent);
313                         cd->channel_ent = p;
314                         if (p) {
315                                 p->proc_fops = &cache_file_operations;
316                                 p->owner = cd->owner;
317                                 p->data = cd;
318                         }
319                 }
320                 if (cd->cache_show) {
321                         p = create_proc_entry("content", S_IFREG|S_IRUSR|S_IWUSR,
322                                               cd->proc_ent);
323                         cd->content_ent = p;
324                         if (p) {
325                                 p->proc_fops = &content_file_operations;
326                                 p->owner = cd->owner;
327                                 p->data = cd;
328                         }
329                 }
330         }
331         rwlock_init(&cd->hash_lock);
332         INIT_LIST_HEAD(&cd->queue);
333         spin_lock(&cache_list_lock);
334         cd->nextcheck = 0;
335         cd->entries = 0;
336         atomic_set(&cd->readers, 0);
337         cd->last_close = 0;
338         cd->last_warn = -1;
339         list_add(&cd->others, &cache_list);
340         spin_unlock(&cache_list_lock);
341
342         /* start the cleaning process */
343         schedule_delayed_work(&cache_cleaner, 0);
344 }
345
346 int cache_unregister(struct cache_detail *cd)
347 {
348         cache_purge(cd);
349         spin_lock(&cache_list_lock);
350         write_lock(&cd->hash_lock);
351         if (cd->entries || atomic_read(&cd->inuse)) {
352                 write_unlock(&cd->hash_lock);
353                 spin_unlock(&cache_list_lock);
354                 return -EBUSY;
355         }
356         if (current_detail == cd)
357                 current_detail = NULL;
358         list_del_init(&cd->others);
359         write_unlock(&cd->hash_lock);
360         spin_unlock(&cache_list_lock);
361         if (cd->proc_ent) {
362                 if (cd->flush_ent)
363                         remove_proc_entry("flush", cd->proc_ent);
364                 if (cd->channel_ent)
365                         remove_proc_entry("channel", cd->proc_ent);
366                 if (cd->content_ent)
367                         remove_proc_entry("content", cd->proc_ent);
368
369                 cd->proc_ent = NULL;
370                 remove_proc_entry(cd->name, proc_net_rpc);
371         }
372         if (list_empty(&cache_list)) {
373                 /* module must be being unloaded so its safe to kill the worker */
374                 cancel_delayed_work(&cache_cleaner);
375                 flush_scheduled_work();
376         }
377         return 0;
378 }
379
380 /* clean cache tries to find something to clean
381  * and cleans it.
382  * It returns 1 if it cleaned something,
383  *            0 if it didn't find anything this time
384  *           -1 if it fell off the end of the list.
385  */
386 static int cache_clean(void)
387 {
388         int rv = 0;
389         struct list_head *next;
390
391         spin_lock(&cache_list_lock);
392
393         /* find a suitable table if we don't already have one */
394         while (current_detail == NULL ||
395             current_index >= current_detail->hash_size) {
396                 if (current_detail)
397                         next = current_detail->others.next;
398                 else
399                         next = cache_list.next;
400                 if (next == &cache_list) {
401                         current_detail = NULL;
402                         spin_unlock(&cache_list_lock);
403                         return -1;
404                 }
405                 current_detail = list_entry(next, struct cache_detail, others);
406                 if (current_detail->nextcheck > get_seconds())
407                         current_index = current_detail->hash_size;
408                 else {
409                         current_index = 0;
410                         current_detail->nextcheck = get_seconds()+30*60;
411                 }
412         }
413
414         /* find a non-empty bucket in the table */
415         while (current_detail &&
416                current_index < current_detail->hash_size &&
417                current_detail->hash_table[current_index] == NULL)
418                 current_index++;
419
420         /* find a cleanable entry in the bucket and clean it, or set to next bucket */
421
422         if (current_detail && current_index < current_detail->hash_size) {
423                 struct cache_head *ch, **cp;
424                 struct cache_detail *d;
425
426                 write_lock(&current_detail->hash_lock);
427
428                 /* Ok, now to clean this strand */
429
430                 cp = & current_detail->hash_table[current_index];
431                 ch = *cp;
432                 for (; ch; cp= & ch->next, ch= *cp) {
433                         if (current_detail->nextcheck > ch->expiry_time)
434                                 current_detail->nextcheck = ch->expiry_time+1;
435                         if (ch->expiry_time >= get_seconds()
436                             && ch->last_refresh >= current_detail->flush_time
437                                 )
438                                 continue;
439                         if (test_and_clear_bit(CACHE_PENDING, &ch->flags))
440                                 queue_loose(current_detail, ch);
441
442                         if (atomic_read(&ch->ref.refcount) == 1)
443                                 break;
444                 }
445                 if (ch) {
446                         *cp = ch->next;
447                         ch->next = NULL;
448                         current_detail->entries--;
449                         rv = 1;
450                 }
451                 write_unlock(&current_detail->hash_lock);
452                 d = current_detail;
453                 if (!ch)
454                         current_index ++;
455                 spin_unlock(&cache_list_lock);
456                 if (ch)
457                         cache_put(ch, d);
458         } else
459                 spin_unlock(&cache_list_lock);
460
461         return rv;
462 }
463
464 /*
465  * We want to regularly clean the cache, so we need to schedule some work ...
466  */
467 static void do_cache_clean(struct work_struct *work)
468 {
469         int delay = 5;
470         if (cache_clean() == -1)
471                 delay = 30*HZ;
472
473         if (list_empty(&cache_list))
474                 delay = 0;
475
476         if (delay)
477                 schedule_delayed_work(&cache_cleaner, delay);
478 }
479
480
481 /*
482  * Clean all caches promptly.  This just calls cache_clean
483  * repeatedly until we are sure that every cache has had a chance to
484  * be fully cleaned
485  */
486 void cache_flush(void)
487 {
488         while (cache_clean() != -1)
489                 cond_resched();
490         while (cache_clean() != -1)
491                 cond_resched();
492 }
493
494 void cache_purge(struct cache_detail *detail)
495 {
496         detail->flush_time = LONG_MAX;
497         detail->nextcheck = get_seconds();
498         cache_flush();
499         detail->flush_time = 1;
500 }
501
502
503
504 /*
505  * Deferral and Revisiting of Requests.
506  *
507  * If a cache lookup finds a pending entry, we
508  * need to defer the request and revisit it later.
509  * All deferred requests are stored in a hash table,
510  * indexed by "struct cache_head *".
511  * As it may be wasteful to store a whole request
512  * structure, we allow the request to provide a
513  * deferred form, which must contain a
514  * 'struct cache_deferred_req'
515  * This cache_deferred_req contains a method to allow
516  * it to be revisited when cache info is available
517  */
518
519 #define DFR_HASHSIZE    (PAGE_SIZE/sizeof(struct list_head))
520 #define DFR_HASH(item)  ((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE)
521
522 #define DFR_MAX 300     /* ??? */
523
524 static DEFINE_SPINLOCK(cache_defer_lock);
525 static LIST_HEAD(cache_defer_list);
526 static struct list_head cache_defer_hash[DFR_HASHSIZE];
527 static int cache_defer_cnt;
528
529 static int cache_defer_req(struct cache_req *req, struct cache_head *item)
530 {
531         struct cache_deferred_req *dreq;
532         int hash = DFR_HASH(item);
533
534         if (cache_defer_cnt >= DFR_MAX) {
535                 /* too much in the cache, randomly drop this one,
536                  * or continue and drop the oldest below
537                  */
538                 if (net_random()&1)
539                         return -ETIMEDOUT;
540         }
541         dreq = req->defer(req);
542         if (dreq == NULL)
543                 return -ETIMEDOUT;
544
545         dreq->item = item;
546         dreq->recv_time = get_seconds();
547
548         spin_lock(&cache_defer_lock);
549
550         list_add(&dreq->recent, &cache_defer_list);
551
552         if (cache_defer_hash[hash].next == NULL)
553                 INIT_LIST_HEAD(&cache_defer_hash[hash]);
554         list_add(&dreq->hash, &cache_defer_hash[hash]);
555
556         /* it is in, now maybe clean up */
557         dreq = NULL;
558         if (++cache_defer_cnt > DFR_MAX) {
559                 dreq = list_entry(cache_defer_list.prev,
560                                   struct cache_deferred_req, recent);
561                 list_del(&dreq->recent);
562                 list_del(&dreq->hash);
563                 cache_defer_cnt--;
564         }
565         spin_unlock(&cache_defer_lock);
566
567         if (dreq) {
568                 /* there was one too many */
569                 dreq->revisit(dreq, 1);
570         }
571         if (!test_bit(CACHE_PENDING, &item->flags)) {
572                 /* must have just been validated... */
573                 cache_revisit_request(item);
574         }
575         return 0;
576 }
577
578 static void cache_revisit_request(struct cache_head *item)
579 {
580         struct cache_deferred_req *dreq;
581         struct list_head pending;
582
583         struct list_head *lp;
584         int hash = DFR_HASH(item);
585
586         INIT_LIST_HEAD(&pending);
587         spin_lock(&cache_defer_lock);
588
589         lp = cache_defer_hash[hash].next;
590         if (lp) {
591                 while (lp != &cache_defer_hash[hash]) {
592                         dreq = list_entry(lp, struct cache_deferred_req, hash);
593                         lp = lp->next;
594                         if (dreq->item == item) {
595                                 list_del(&dreq->hash);
596                                 list_move(&dreq->recent, &pending);
597                                 cache_defer_cnt--;
598                         }
599                 }
600         }
601         spin_unlock(&cache_defer_lock);
602
603         while (!list_empty(&pending)) {
604                 dreq = list_entry(pending.next, struct cache_deferred_req, recent);
605                 list_del_init(&dreq->recent);
606                 dreq->revisit(dreq, 0);
607         }
608 }
609
610 void cache_clean_deferred(void *owner)
611 {
612         struct cache_deferred_req *dreq, *tmp;
613         struct list_head pending;
614
615
616         INIT_LIST_HEAD(&pending);
617         spin_lock(&cache_defer_lock);
618
619         list_for_each_entry_safe(dreq, tmp, &cache_defer_list, recent) {
620                 if (dreq->owner == owner) {
621                         list_del(&dreq->hash);
622                         list_move(&dreq->recent, &pending);
623                         cache_defer_cnt--;
624                 }
625         }
626         spin_unlock(&cache_defer_lock);
627
628         while (!list_empty(&pending)) {
629                 dreq = list_entry(pending.next, struct cache_deferred_req, recent);
630                 list_del_init(&dreq->recent);
631                 dreq->revisit(dreq, 1);
632         }
633 }
634
635 /*
636  * communicate with user-space
637  *
638  * We have a magic /proc file - /proc/sunrpc/cache
639  * On read, you get a full request, or block
640  * On write, an update request is processed
641  * Poll works if anything to read, and always allows write
642  *
643  * Implemented by linked list of requests.  Each open file has
644  * a ->private that also exists in this list.  New request are added
645  * to the end and may wakeup and preceding readers.
646  * New readers are added to the head.  If, on read, an item is found with
647  * CACHE_UPCALLING clear, we free it from the list.
648  *
649  */
650
651 static DEFINE_SPINLOCK(queue_lock);
652 static DEFINE_MUTEX(queue_io_mutex);
653
654 struct cache_queue {
655         struct list_head        list;
656         int                     reader; /* if 0, then request */
657 };
658 struct cache_request {
659         struct cache_queue      q;
660         struct cache_head       *item;
661         char                    * buf;
662         int                     len;
663         int                     readers;
664 };
665 struct cache_reader {
666         struct cache_queue      q;
667         int                     offset; /* if non-0, we have a refcnt on next request */
668 };
669
670 static ssize_t
671 cache_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
672 {
673         struct cache_reader *rp = filp->private_data;
674         struct cache_request *rq;
675         struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;
676         int err;
677
678         if (count == 0)
679                 return 0;
680
681         mutex_lock(&queue_io_mutex); /* protect against multiple concurrent
682                               * readers on this file */
683  again:
684         spin_lock(&queue_lock);
685         /* need to find next request */
686         while (rp->q.list.next != &cd->queue &&
687                list_entry(rp->q.list.next, struct cache_queue, list)
688                ->reader) {
689                 struct list_head *next = rp->q.list.next;
690                 list_move(&rp->q.list, next);
691         }
692         if (rp->q.list.next == &cd->queue) {
693                 spin_unlock(&queue_lock);
694                 mutex_unlock(&queue_io_mutex);
695                 BUG_ON(rp->offset);
696                 return 0;
697         }
698         rq = container_of(rp->q.list.next, struct cache_request, q.list);
699         BUG_ON(rq->q.reader);
700         if (rp->offset == 0)
701                 rq->readers++;
702         spin_unlock(&queue_lock);
703
704         if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) {
705                 err = -EAGAIN;
706                 spin_lock(&queue_lock);
707                 list_move(&rp->q.list, &rq->q.list);
708                 spin_unlock(&queue_lock);
709         } else {
710                 if (rp->offset + count > rq->len)
711                         count = rq->len - rp->offset;
712                 err = -EFAULT;
713                 if (copy_to_user(buf, rq->buf + rp->offset, count))
714                         goto out;
715                 rp->offset += count;
716                 if (rp->offset >= rq->len) {
717                         rp->offset = 0;
718                         spin_lock(&queue_lock);
719                         list_move(&rp->q.list, &rq->q.list);
720                         spin_unlock(&queue_lock);
721                 }
722                 err = 0;
723         }
724  out:
725         if (rp->offset == 0) {
726                 /* need to release rq */
727                 spin_lock(&queue_lock);
728                 rq->readers--;
729                 if (rq->readers == 0 &&
730                     !test_bit(CACHE_PENDING, &rq->item->flags)) {
731                         list_del(&rq->q.list);
732                         spin_unlock(&queue_lock);
733                         cache_put(rq->item, cd);
734                         kfree(rq->buf);
735                         kfree(rq);
736                 } else
737                         spin_unlock(&queue_lock);
738         }
739         if (err == -EAGAIN)
740                 goto again;
741         mutex_unlock(&queue_io_mutex);
742         return err ? err :  count;
743 }
744
745 static char write_buf[8192]; /* protected by queue_io_mutex */
746
747 static ssize_t
748 cache_write(struct file *filp, const char __user *buf, size_t count,
749             loff_t *ppos)
750 {
751         int err;
752         struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;
753
754         if (count == 0)
755                 return 0;
756         if (count >= sizeof(write_buf))
757                 return -EINVAL;
758
759         mutex_lock(&queue_io_mutex);
760
761         if (copy_from_user(write_buf, buf, count)) {
762                 mutex_unlock(&queue_io_mutex);
763                 return -EFAULT;
764         }
765         write_buf[count] = '\0';
766         if (cd->cache_parse)
767                 err = cd->cache_parse(cd, write_buf, count);
768         else
769                 err = -EINVAL;
770
771         mutex_unlock(&queue_io_mutex);
772         return err ? err : count;
773 }
774
775 static DECLARE_WAIT_QUEUE_HEAD(queue_wait);
776
777 static unsigned int
778 cache_poll(struct file *filp, poll_table *wait)
779 {
780         unsigned int mask;
781         struct cache_reader *rp = filp->private_data;
782         struct cache_queue *cq;
783         struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;
784
785         poll_wait(filp, &queue_wait, wait);
786
787         /* alway allow write */
788         mask = POLL_OUT | POLLWRNORM;
789
790         if (!rp)
791                 return mask;
792
793         spin_lock(&queue_lock);
794
795         for (cq= &rp->q; &cq->list != &cd->queue;
796              cq = list_entry(cq->list.next, struct cache_queue, list))
797                 if (!cq->reader) {
798                         mask |= POLLIN | POLLRDNORM;
799                         break;
800                 }
801         spin_unlock(&queue_lock);
802         return mask;
803 }
804
805 static int
806 cache_ioctl(struct inode *ino, struct file *filp,
807             unsigned int cmd, unsigned long arg)
808 {
809         int len = 0;
810         struct cache_reader *rp = filp->private_data;
811         struct cache_queue *cq;
812         struct cache_detail *cd = PDE(ino)->data;
813
814         if (cmd != FIONREAD || !rp)
815                 return -EINVAL;
816
817         spin_lock(&queue_lock);
818
819         /* only find the length remaining in current request,
820          * or the length of the next request
821          */
822         for (cq= &rp->q; &cq->list != &cd->queue;
823              cq = list_entry(cq->list.next, struct cache_queue, list))
824                 if (!cq->reader) {
825                         struct cache_request *cr =
826                                 container_of(cq, struct cache_request, q);
827                         len = cr->len - rp->offset;
828                         break;
829                 }
830         spin_unlock(&queue_lock);
831
832         return put_user(len, (int __user *)arg);
833 }
834
835 static int
836 cache_open(struct inode *inode, struct file *filp)
837 {
838         struct cache_reader *rp = NULL;
839
840         nonseekable_open(inode, filp);
841         if (filp->f_mode & FMODE_READ) {
842                 struct cache_detail *cd = PDE(inode)->data;
843
844                 rp = kmalloc(sizeof(*rp), GFP_KERNEL);
845                 if (!rp)
846                         return -ENOMEM;
847                 rp->offset = 0;
848                 rp->q.reader = 1;
849                 atomic_inc(&cd->readers);
850                 spin_lock(&queue_lock);
851                 list_add(&rp->q.list, &cd->queue);
852                 spin_unlock(&queue_lock);
853         }
854         filp->private_data = rp;
855         return 0;
856 }
857
858 static int
859 cache_release(struct inode *inode, struct file *filp)
860 {
861         struct cache_reader *rp = filp->private_data;
862         struct cache_detail *cd = PDE(inode)->data;
863
864         if (rp) {
865                 spin_lock(&queue_lock);
866                 if (rp->offset) {
867                         struct cache_queue *cq;
868                         for (cq= &rp->q; &cq->list != &cd->queue;
869                              cq = list_entry(cq->list.next, struct cache_queue, list))
870                                 if (!cq->reader) {
871                                         container_of(cq, struct cache_request, q)
872                                                 ->readers--;
873                                         break;
874                                 }
875                         rp->offset = 0;
876                 }
877                 list_del(&rp->q.list);
878                 spin_unlock(&queue_lock);
879
880                 filp->private_data = NULL;
881                 kfree(rp);
882
883                 cd->last_close = get_seconds();
884                 atomic_dec(&cd->readers);
885         }
886         return 0;
887 }
888
889
890
891 static const struct file_operations cache_file_operations = {
892         .owner          = THIS_MODULE,
893         .llseek         = no_llseek,
894         .read           = cache_read,
895         .write          = cache_write,
896         .poll           = cache_poll,
897         .ioctl          = cache_ioctl, /* for FIONREAD */
898         .open           = cache_open,
899         .release        = cache_release,
900 };
901
902
903 static void queue_loose(struct cache_detail *detail, struct cache_head *ch)
904 {
905         struct cache_queue *cq;
906         spin_lock(&queue_lock);
907         list_for_each_entry(cq, &detail->queue, list)
908                 if (!cq->reader) {
909                         struct cache_request *cr = container_of(cq, struct cache_request, q);
910                         if (cr->item != ch)
911                                 continue;
912                         if (cr->readers != 0)
913                                 continue;
914                         list_del(&cr->q.list);
915                         spin_unlock(&queue_lock);
916                         cache_put(cr->item, detail);
917                         kfree(cr->buf);
918                         kfree(cr);
919                         return;
920                 }
921         spin_unlock(&queue_lock);
922 }
923
924 /*
925  * Support routines for text-based upcalls.
926  * Fields are separated by spaces.
927  * Fields are either mangled to quote space tab newline slosh with slosh
928  * or a hexified with a leading \x
929  * Record is terminated with newline.
930  *
931  */
932
933 void qword_add(char **bpp, int *lp, char *str)
934 {
935         char *bp = *bpp;
936         int len = *lp;
937         char c;
938
939         if (len < 0) return;
940
941         while ((c=*str++) && len)
942                 switch(c) {
943                 case ' ':
944                 case '\t':
945                 case '\n':
946                 case '\\':
947                         if (len >= 4) {
948                                 *bp++ = '\\';
949                                 *bp++ = '0' + ((c & 0300)>>6);
950                                 *bp++ = '0' + ((c & 0070)>>3);
951                                 *bp++ = '0' + ((c & 0007)>>0);
952                         }
953                         len -= 4;
954                         break;
955                 default:
956                         *bp++ = c;
957                         len--;
958                 }
959         if (c || len <1) len = -1;
960         else {
961                 *bp++ = ' ';
962                 len--;
963         }
964         *bpp = bp;
965         *lp = len;
966 }
967
968 void qword_addhex(char **bpp, int *lp, char *buf, int blen)
969 {
970         char *bp = *bpp;
971         int len = *lp;
972
973         if (len < 0) return;
974
975         if (len > 2) {
976                 *bp++ = '\\';
977                 *bp++ = 'x';
978                 len -= 2;
979                 while (blen && len >= 2) {
980                         unsigned char c = *buf++;
981                         *bp++ = '0' + ((c&0xf0)>>4) + (c>=0xa0)*('a'-'9'-1);
982                         *bp++ = '0' + (c&0x0f) + ((c&0x0f)>=0x0a)*('a'-'9'-1);
983                         len -= 2;
984                         blen--;
985                 }
986         }
987         if (blen || len<1) len = -1;
988         else {
989                 *bp++ = ' ';
990                 len--;
991         }
992         *bpp = bp;
993         *lp = len;
994 }
995
996 static void warn_no_listener(struct cache_detail *detail)
997 {
998         if (detail->last_warn != detail->last_close) {
999                 detail->last_warn = detail->last_close;
1000                 if (detail->warn_no_listener)
1001                         detail->warn_no_listener(detail);
1002         }
1003 }
1004
1005 /*
1006  * register an upcall request to user-space.
1007  * Each request is at most one page long.
1008  */
1009 static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h)
1010 {
1011
1012         char *buf;
1013         struct cache_request *crq;
1014         char *bp;
1015         int len;
1016
1017         if (detail->cache_request == NULL)
1018                 return -EINVAL;
1019
1020         if (atomic_read(&detail->readers) == 0 &&
1021             detail->last_close < get_seconds() - 30) {
1022                         warn_no_listener(detail);
1023                         return -EINVAL;
1024         }
1025
1026         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
1027         if (!buf)
1028                 return -EAGAIN;
1029
1030         crq = kmalloc(sizeof (*crq), GFP_KERNEL);
1031         if (!crq) {
1032                 kfree(buf);
1033                 return -EAGAIN;
1034         }
1035
1036         bp = buf; len = PAGE_SIZE;
1037
1038         detail->cache_request(detail, h, &bp, &len);
1039
1040         if (len < 0) {
1041                 kfree(buf);
1042                 kfree(crq);
1043                 return -EAGAIN;
1044         }
1045         crq->q.reader = 0;
1046         crq->item = cache_get(h);
1047         crq->buf = buf;
1048         crq->len = PAGE_SIZE - len;
1049         crq->readers = 0;
1050         spin_lock(&queue_lock);
1051         list_add_tail(&crq->q.list, &detail->queue);
1052         spin_unlock(&queue_lock);
1053         wake_up(&queue_wait);
1054         return 0;
1055 }
1056
1057 /*
1058  * parse a message from user-space and pass it
1059  * to an appropriate cache
1060  * Messages are, like requests, separated into fields by
1061  * spaces and dequotes as \xHEXSTRING or embedded \nnn octal
1062  *
1063  * Message is
1064  *   reply cachename expiry key ... content....
1065  *
1066  * key and content are both parsed by cache
1067  */
1068
1069 #define isodigit(c) (isdigit(c) && c <= '7')
1070 int qword_get(char **bpp, char *dest, int bufsize)
1071 {
1072         /* return bytes copied, or -1 on error */
1073         char *bp = *bpp;
1074         int len = 0;
1075
1076         while (*bp == ' ') bp++;
1077
1078         if (bp[0] == '\\' && bp[1] == 'x') {
1079                 /* HEX STRING */
1080                 bp += 2;
1081                 while (isxdigit(bp[0]) && isxdigit(bp[1]) && len < bufsize) {
1082                         int byte = isdigit(*bp) ? *bp-'0' : toupper(*bp)-'A'+10;
1083                         bp++;
1084                         byte <<= 4;
1085                         byte |= isdigit(*bp) ? *bp-'0' : toupper(*bp)-'A'+10;
1086                         *dest++ = byte;
1087                         bp++;
1088                         len++;
1089                 }
1090         } else {
1091                 /* text with \nnn octal quoting */
1092                 while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) {
1093                         if (*bp == '\\' &&
1094                             isodigit(bp[1]) && (bp[1] <= '3') &&
1095                             isodigit(bp[2]) &&
1096                             isodigit(bp[3])) {
1097                                 int byte = (*++bp -'0');
1098                                 bp++;
1099                                 byte = (byte << 3) | (*bp++ - '0');
1100                                 byte = (byte << 3) | (*bp++ - '0');
1101                                 *dest++ = byte;
1102                                 len++;
1103                         } else {
1104                                 *dest++ = *bp++;
1105                                 len++;
1106                         }
1107                 }
1108         }
1109
1110         if (*bp != ' ' && *bp != '\n' && *bp != '\0')
1111                 return -1;
1112         while (*bp == ' ') bp++;
1113         *bpp = bp;
1114         *dest = '\0';
1115         return len;
1116 }
1117
1118
1119 /*
1120  * support /proc/sunrpc/cache/$CACHENAME/content
1121  * as a seqfile.
1122  * We call ->cache_show passing NULL for the item to
1123  * get a header, then pass each real item in the cache
1124  */
1125
1126 struct handle {
1127         struct cache_detail *cd;
1128 };
1129
1130 static void *c_start(struct seq_file *m, loff_t *pos)
1131 {
1132         loff_t n = *pos;
1133         unsigned hash, entry;
1134         struct cache_head *ch;
1135         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1136
1137
1138         read_lock(&cd->hash_lock);
1139         if (!n--)
1140                 return SEQ_START_TOKEN;
1141         hash = n >> 32;
1142         entry = n & ((1LL<<32) - 1);
1143
1144         for (ch=cd->hash_table[hash]; ch; ch=ch->next)
1145                 if (!entry--)
1146                         return ch;
1147         n &= ~((1LL<<32) - 1);
1148         do {
1149                 hash++;
1150                 n += 1LL<<32;
1151         } while(hash < cd->hash_size &&
1152                 cd->hash_table[hash]==NULL);
1153         if (hash >= cd->hash_size)
1154                 return NULL;
1155         *pos = n+1;
1156         return cd->hash_table[hash];
1157 }
1158
1159 static void *c_next(struct seq_file *m, void *p, loff_t *pos)
1160 {
1161         struct cache_head *ch = p;
1162         int hash = (*pos >> 32);
1163         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1164
1165         if (p == SEQ_START_TOKEN)
1166                 hash = 0;
1167         else if (ch->next == NULL) {
1168                 hash++;
1169                 *pos += 1LL<<32;
1170         } else {
1171                 ++*pos;
1172                 return ch->next;
1173         }
1174         *pos &= ~((1LL<<32) - 1);
1175         while (hash < cd->hash_size &&
1176                cd->hash_table[hash] == NULL) {
1177                 hash++;
1178                 *pos += 1LL<<32;
1179         }
1180         if (hash >= cd->hash_size)
1181                 return NULL;
1182         ++*pos;
1183         return cd->hash_table[hash];
1184 }
1185
1186 static void c_stop(struct seq_file *m, void *p)
1187 {
1188         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1189         read_unlock(&cd->hash_lock);
1190 }
1191
1192 static int c_show(struct seq_file *m, void *p)
1193 {
1194         struct cache_head *cp = p;
1195         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1196
1197         if (p == SEQ_START_TOKEN)
1198                 return cd->cache_show(m, cd, NULL);
1199
1200         ifdebug(CACHE)
1201                 seq_printf(m, "# expiry=%ld refcnt=%d flags=%lx\n",
1202                            cp->expiry_time, atomic_read(&cp->ref.refcount), cp->flags);
1203         cache_get(cp);
1204         if (cache_check(cd, cp, NULL))
1205                 /* cache_check does a cache_put on failure */
1206                 seq_printf(m, "# ");
1207         else
1208                 cache_put(cp, cd);
1209
1210         return cd->cache_show(m, cd, cp);
1211 }
1212
1213 static struct seq_operations cache_content_op = {
1214         .start  = c_start,
1215         .next   = c_next,
1216         .stop   = c_stop,
1217         .show   = c_show,
1218 };
1219
1220 static int content_open(struct inode *inode, struct file *file)
1221 {
1222         int res;
1223         struct handle *han;
1224         struct cache_detail *cd = PDE(inode)->data;
1225
1226         han = kmalloc(sizeof(*han), GFP_KERNEL);
1227         if (han == NULL)
1228                 return -ENOMEM;
1229
1230         han->cd = cd;
1231
1232         res = seq_open(file, &cache_content_op);
1233         if (res)
1234                 kfree(han);
1235         else
1236                 ((struct seq_file *)file->private_data)->private = han;
1237
1238         return res;
1239 }
1240 static int content_release(struct inode *inode, struct file *file)
1241 {
1242         struct seq_file *m = (struct seq_file *)file->private_data;
1243         struct handle *han = m->private;
1244         kfree(han);
1245         m->private = NULL;
1246         return seq_release(inode, file);
1247 }
1248
1249 static const struct file_operations content_file_operations = {
1250         .open           = content_open,
1251         .read           = seq_read,
1252         .llseek         = seq_lseek,
1253         .release        = content_release,
1254 };
1255
1256 static ssize_t read_flush(struct file *file, char __user *buf,
1257                             size_t count, loff_t *ppos)
1258 {
1259         struct cache_detail *cd = PDE(file->f_path.dentry->d_inode)->data;
1260         char tbuf[20];
1261         unsigned long p = *ppos;
1262         int len;
1263
1264         sprintf(tbuf, "%lu\n", cd->flush_time);
1265         len = strlen(tbuf);
1266         if (p >= len)
1267                 return 0;
1268         len -= p;
1269         if (len > count) len = count;
1270         if (copy_to_user(buf, (void*)(tbuf+p), len))
1271                 len = -EFAULT;
1272         else
1273                 *ppos += len;
1274         return len;
1275 }
1276
1277 static ssize_t write_flush(struct file * file, const char __user * buf,
1278                              size_t count, loff_t *ppos)
1279 {
1280         struct cache_detail *cd = PDE(file->f_path.dentry->d_inode)->data;
1281         char tbuf[20];
1282         char *ep;
1283         long flushtime;
1284         if (*ppos || count > sizeof(tbuf)-1)
1285                 return -EINVAL;
1286         if (copy_from_user(tbuf, buf, count))
1287                 return -EFAULT;
1288         tbuf[count] = 0;
1289         flushtime = simple_strtoul(tbuf, &ep, 0);
1290         if (*ep && *ep != '\n')
1291                 return -EINVAL;
1292
1293         cd->flush_time = flushtime;
1294         cd->nextcheck = get_seconds();
1295         cache_flush();
1296
1297         *ppos += count;
1298         return count;
1299 }
1300
1301 static const struct file_operations cache_flush_operations = {
1302         .open           = nonseekable_open,
1303         .read           = read_flush,
1304         .write          = write_flush,
1305 };