[NET] sem2mutex: net/
[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 void cache_init(struct cache_head *h)
41 {
42         time_t now = get_seconds();
43         h->next = NULL;
44         h->flags = 0;
45         atomic_set(&h->refcnt, 1);
46         h->expiry_time = now + CACHE_NEW_EXPIRY;
47         h->last_refresh = now;
48 }
49
50
51 static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h);
52 /*
53  * This is the generic cache management routine for all
54  * the authentication caches.
55  * It checks the currency of a cache item and will (later)
56  * initiate an upcall to fill it if needed.
57  *
58  *
59  * Returns 0 if the cache_head can be used, or cache_puts it and returns
60  * -EAGAIN if upcall is pending,
61  * -ENOENT if cache entry was negative
62  */
63 int cache_check(struct cache_detail *detail,
64                     struct cache_head *h, struct cache_req *rqstp)
65 {
66         int rv;
67         long refresh_age, age;
68
69         /* First decide return status as best we can */
70         if (!test_bit(CACHE_VALID, &h->flags) ||
71             h->expiry_time < get_seconds())
72                 rv = -EAGAIN;
73         else if (detail->flush_time > h->last_refresh)
74                 rv = -EAGAIN;
75         else {
76                 /* entry is valid */
77                 if (test_bit(CACHE_NEGATIVE, &h->flags))
78                         rv = -ENOENT;
79                 else rv = 0;
80         }
81
82         /* now see if we want to start an upcall */
83         refresh_age = (h->expiry_time - h->last_refresh);
84         age = get_seconds() - h->last_refresh;
85
86         if (rqstp == NULL) {
87                 if (rv == -EAGAIN)
88                         rv = -ENOENT;
89         } else if (rv == -EAGAIN || age > refresh_age/2) {
90                 dprintk("Want update, refage=%ld, age=%ld\n", refresh_age, age);
91                 if (!test_and_set_bit(CACHE_PENDING, &h->flags)) {
92                         switch (cache_make_upcall(detail, h)) {
93                         case -EINVAL:
94                                 clear_bit(CACHE_PENDING, &h->flags);
95                                 if (rv == -EAGAIN) {
96                                         set_bit(CACHE_NEGATIVE, &h->flags);
97                                         cache_fresh(detail, h, get_seconds()+CACHE_NEW_EXPIRY);
98                                         rv = -ENOENT;
99                                 }
100                                 break;
101
102                         case -EAGAIN:
103                                 clear_bit(CACHE_PENDING, &h->flags);
104                                 cache_revisit_request(h);
105                                 break;
106                         }
107                 }
108         }
109
110         if (rv == -EAGAIN)
111                 cache_defer_req(rqstp, h);
112
113         if (rv && h)
114                 detail->cache_put(h, detail);
115         return rv;
116 }
117
118 static void queue_loose(struct cache_detail *detail, struct cache_head *ch);
119
120 void cache_fresh(struct cache_detail *detail,
121                  struct cache_head *head, time_t expiry)
122 {
123
124         head->expiry_time = expiry;
125         head->last_refresh = get_seconds();
126         if (!test_and_set_bit(CACHE_VALID, &head->flags))
127                 cache_revisit_request(head);
128         if (test_and_clear_bit(CACHE_PENDING, &head->flags))
129                 queue_loose(detail, head);
130 }
131
132 /*
133  * caches need to be periodically cleaned.
134  * For this we maintain a list of cache_detail and
135  * a current pointer into that list and into the table
136  * for that entry.
137  *
138  * Each time clean_cache is called it finds the next non-empty entry
139  * in the current table and walks the list in that entry
140  * looking for entries that can be removed.
141  *
142  * An entry gets removed if:
143  * - The expiry is before current time
144  * - The last_refresh time is before the flush_time for that cache
145  *
146  * later we might drop old entries with non-NEVER expiry if that table
147  * is getting 'full' for some definition of 'full'
148  *
149  * The question of "how often to scan a table" is an interesting one
150  * and is answered in part by the use of the "nextcheck" field in the
151  * cache_detail.
152  * When a scan of a table begins, the nextcheck field is set to a time
153  * that is well into the future.
154  * While scanning, if an expiry time is found that is earlier than the
155  * current nextcheck time, nextcheck is set to that expiry time.
156  * If the flush_time is ever set to a time earlier than the nextcheck
157  * time, the nextcheck time is then set to that flush_time.
158  *
159  * A table is then only scanned if the current time is at least
160  * the nextcheck time.
161  * 
162  */
163
164 static LIST_HEAD(cache_list);
165 static DEFINE_SPINLOCK(cache_list_lock);
166 static struct cache_detail *current_detail;
167 static int current_index;
168
169 static struct file_operations cache_file_operations;
170 static struct file_operations content_file_operations;
171 static struct file_operations cache_flush_operations;
172
173 static void do_cache_clean(void *data);
174 static DECLARE_WORK(cache_cleaner, do_cache_clean, NULL);
175
176 void cache_register(struct cache_detail *cd)
177 {
178         cd->proc_ent = proc_mkdir(cd->name, proc_net_rpc);
179         if (cd->proc_ent) {
180                 struct proc_dir_entry *p;
181                 cd->proc_ent->owner = cd->owner;
182                 cd->channel_ent = cd->content_ent = NULL;
183                 
184                 p = create_proc_entry("flush", S_IFREG|S_IRUSR|S_IWUSR,
185                                       cd->proc_ent);
186                 cd->flush_ent =  p;
187                 if (p) {
188                         p->proc_fops = &cache_flush_operations;
189                         p->owner = cd->owner;
190                         p->data = cd;
191                 }
192  
193                 if (cd->cache_request || cd->cache_parse) {
194                         p = create_proc_entry("channel", S_IFREG|S_IRUSR|S_IWUSR,
195                                               cd->proc_ent);
196                         cd->channel_ent = p;
197                         if (p) {
198                                 p->proc_fops = &cache_file_operations;
199                                 p->owner = cd->owner;
200                                 p->data = cd;
201                         }
202                 }
203                 if (cd->cache_show) {
204                         p = create_proc_entry("content", S_IFREG|S_IRUSR|S_IWUSR,
205                                               cd->proc_ent);
206                         cd->content_ent = p;
207                         if (p) {
208                                 p->proc_fops = &content_file_operations;
209                                 p->owner = cd->owner;
210                                 p->data = cd;
211                         }
212                 }
213         }
214         rwlock_init(&cd->hash_lock);
215         INIT_LIST_HEAD(&cd->queue);
216         spin_lock(&cache_list_lock);
217         cd->nextcheck = 0;
218         cd->entries = 0;
219         atomic_set(&cd->readers, 0);
220         cd->last_close = 0;
221         cd->last_warn = -1;
222         list_add(&cd->others, &cache_list);
223         spin_unlock(&cache_list_lock);
224
225         /* start the cleaning process */
226         schedule_work(&cache_cleaner);
227 }
228
229 int cache_unregister(struct cache_detail *cd)
230 {
231         cache_purge(cd);
232         spin_lock(&cache_list_lock);
233         write_lock(&cd->hash_lock);
234         if (cd->entries || atomic_read(&cd->inuse)) {
235                 write_unlock(&cd->hash_lock);
236                 spin_unlock(&cache_list_lock);
237                 return -EBUSY;
238         }
239         if (current_detail == cd)
240                 current_detail = NULL;
241         list_del_init(&cd->others);
242         write_unlock(&cd->hash_lock);
243         spin_unlock(&cache_list_lock);
244         if (cd->proc_ent) {
245                 if (cd->flush_ent)
246                         remove_proc_entry("flush", cd->proc_ent);
247                 if (cd->channel_ent)
248                         remove_proc_entry("channel", cd->proc_ent);
249                 if (cd->content_ent)
250                         remove_proc_entry("content", cd->proc_ent);
251
252                 cd->proc_ent = NULL;
253                 remove_proc_entry(cd->name, proc_net_rpc);
254         }
255         if (list_empty(&cache_list)) {
256                 /* module must be being unloaded so its safe to kill the worker */
257                 cancel_delayed_work(&cache_cleaner);
258                 flush_scheduled_work();
259         }
260         return 0;
261 }
262
263 /* clean cache tries to find something to clean
264  * and cleans it.
265  * It returns 1 if it cleaned something,
266  *            0 if it didn't find anything this time
267  *           -1 if it fell off the end of the list.
268  */
269 static int cache_clean(void)
270 {
271         int rv = 0;
272         struct list_head *next;
273
274         spin_lock(&cache_list_lock);
275
276         /* find a suitable table if we don't already have one */
277         while (current_detail == NULL ||
278             current_index >= current_detail->hash_size) {
279                 if (current_detail)
280                         next = current_detail->others.next;
281                 else
282                         next = cache_list.next;
283                 if (next == &cache_list) {
284                         current_detail = NULL;
285                         spin_unlock(&cache_list_lock);
286                         return -1;
287                 }
288                 current_detail = list_entry(next, struct cache_detail, others);
289                 if (current_detail->nextcheck > get_seconds())
290                         current_index = current_detail->hash_size;
291                 else {
292                         current_index = 0;
293                         current_detail->nextcheck = get_seconds()+30*60;
294                 }
295         }
296
297         /* find a non-empty bucket in the table */
298         while (current_detail &&
299                current_index < current_detail->hash_size &&
300                current_detail->hash_table[current_index] == NULL)
301                 current_index++;
302
303         /* find a cleanable entry in the bucket and clean it, or set to next bucket */
304         
305         if (current_detail && current_index < current_detail->hash_size) {
306                 struct cache_head *ch, **cp;
307                 struct cache_detail *d;
308                 
309                 write_lock(&current_detail->hash_lock);
310
311                 /* Ok, now to clean this strand */
312                         
313                 cp = & current_detail->hash_table[current_index];
314                 ch = *cp;
315                 for (; ch; cp= & ch->next, ch= *cp) {
316                         if (current_detail->nextcheck > ch->expiry_time)
317                                 current_detail->nextcheck = ch->expiry_time+1;
318                         if (ch->expiry_time >= get_seconds()
319                             && ch->last_refresh >= current_detail->flush_time
320                                 )
321                                 continue;
322                         if (test_and_clear_bit(CACHE_PENDING, &ch->flags))
323                                 queue_loose(current_detail, ch);
324
325                         if (atomic_read(&ch->refcnt) == 1)
326                                 break;
327                 }
328                 if (ch) {
329                         *cp = ch->next;
330                         ch->next = NULL;
331                         current_detail->entries--;
332                         rv = 1;
333                 }
334                 write_unlock(&current_detail->hash_lock);
335                 d = current_detail;
336                 if (!ch)
337                         current_index ++;
338                 spin_unlock(&cache_list_lock);
339                 if (ch)
340                         d->cache_put(ch, d);
341         } else
342                 spin_unlock(&cache_list_lock);
343
344         return rv;
345 }
346
347 /*
348  * We want to regularly clean the cache, so we need to schedule some work ...
349  */
350 static void do_cache_clean(void *data)
351 {
352         int delay = 5;
353         if (cache_clean() == -1)
354                 delay = 30*HZ;
355
356         if (list_empty(&cache_list))
357                 delay = 0;
358
359         if (delay)
360                 schedule_delayed_work(&cache_cleaner, delay);
361 }
362
363
364 /* 
365  * Clean all caches promptly.  This just calls cache_clean
366  * repeatedly until we are sure that every cache has had a chance to 
367  * be fully cleaned
368  */
369 void cache_flush(void)
370 {
371         while (cache_clean() != -1)
372                 cond_resched();
373         while (cache_clean() != -1)
374                 cond_resched();
375 }
376
377 void cache_purge(struct cache_detail *detail)
378 {
379         detail->flush_time = LONG_MAX;
380         detail->nextcheck = get_seconds();
381         cache_flush();
382         detail->flush_time = 1;
383 }
384
385
386
387 /*
388  * Deferral and Revisiting of Requests.
389  *
390  * If a cache lookup finds a pending entry, we
391  * need to defer the request and revisit it later.
392  * All deferred requests are stored in a hash table,
393  * indexed by "struct cache_head *".
394  * As it may be wasteful to store a whole request
395  * structure, we allow the request to provide a 
396  * deferred form, which must contain a
397  * 'struct cache_deferred_req'
398  * This cache_deferred_req contains a method to allow
399  * it to be revisited when cache info is available
400  */
401
402 #define DFR_HASHSIZE    (PAGE_SIZE/sizeof(struct list_head))
403 #define DFR_HASH(item)  ((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE)
404
405 #define DFR_MAX 300     /* ??? */
406
407 static DEFINE_SPINLOCK(cache_defer_lock);
408 static LIST_HEAD(cache_defer_list);
409 static struct list_head cache_defer_hash[DFR_HASHSIZE];
410 static int cache_defer_cnt;
411
412 static void cache_defer_req(struct cache_req *req, struct cache_head *item)
413 {
414         struct cache_deferred_req *dreq;
415         int hash = DFR_HASH(item);
416
417         dreq = req->defer(req);
418         if (dreq == NULL)
419                 return;
420
421         dreq->item = item;
422         dreq->recv_time = get_seconds();
423
424         spin_lock(&cache_defer_lock);
425
426         list_add(&dreq->recent, &cache_defer_list);
427
428         if (cache_defer_hash[hash].next == NULL)
429                 INIT_LIST_HEAD(&cache_defer_hash[hash]);
430         list_add(&dreq->hash, &cache_defer_hash[hash]);
431
432         /* it is in, now maybe clean up */
433         dreq = NULL;
434         if (++cache_defer_cnt > DFR_MAX) {
435                 /* too much in the cache, randomly drop
436                  * first or last
437                  */
438                 if (net_random()&1) 
439                         dreq = list_entry(cache_defer_list.next,
440                                           struct cache_deferred_req,
441                                           recent);
442                 else
443                         dreq = list_entry(cache_defer_list.prev,
444                                           struct cache_deferred_req,
445                                           recent);
446                 list_del(&dreq->recent);
447                 list_del(&dreq->hash);
448                 cache_defer_cnt--;
449         }
450         spin_unlock(&cache_defer_lock);
451
452         if (dreq) {
453                 /* there was one too many */
454                 dreq->revisit(dreq, 1);
455         }
456         if (test_bit(CACHE_VALID, &item->flags)) {
457                 /* must have just been validated... */
458                 cache_revisit_request(item);
459         }
460 }
461
462 static void cache_revisit_request(struct cache_head *item)
463 {
464         struct cache_deferred_req *dreq;
465         struct list_head pending;
466
467         struct list_head *lp;
468         int hash = DFR_HASH(item);
469
470         INIT_LIST_HEAD(&pending);
471         spin_lock(&cache_defer_lock);
472         
473         lp = cache_defer_hash[hash].next;
474         if (lp) {
475                 while (lp != &cache_defer_hash[hash]) {
476                         dreq = list_entry(lp, struct cache_deferred_req, hash);
477                         lp = lp->next;
478                         if (dreq->item == item) {
479                                 list_del(&dreq->hash);
480                                 list_move(&dreq->recent, &pending);
481                                 cache_defer_cnt--;
482                         }
483                 }
484         }
485         spin_unlock(&cache_defer_lock);
486
487         while (!list_empty(&pending)) {
488                 dreq = list_entry(pending.next, struct cache_deferred_req, recent);
489                 list_del_init(&dreq->recent);
490                 dreq->revisit(dreq, 0);
491         }
492 }
493
494 void cache_clean_deferred(void *owner)
495 {
496         struct cache_deferred_req *dreq, *tmp;
497         struct list_head pending;
498
499
500         INIT_LIST_HEAD(&pending);
501         spin_lock(&cache_defer_lock);
502         
503         list_for_each_entry_safe(dreq, tmp, &cache_defer_list, recent) {
504                 if (dreq->owner == owner) {
505                         list_del(&dreq->hash);
506                         list_move(&dreq->recent, &pending);
507                         cache_defer_cnt--;
508                 }
509         }
510         spin_unlock(&cache_defer_lock);
511
512         while (!list_empty(&pending)) {
513                 dreq = list_entry(pending.next, struct cache_deferred_req, recent);
514                 list_del_init(&dreq->recent);
515                 dreq->revisit(dreq, 1);
516         }
517 }
518
519 /*
520  * communicate with user-space
521  *
522  * We have a magic /proc file - /proc/sunrpc/cache
523  * On read, you get a full request, or block
524  * On write, an update request is processed
525  * Poll works if anything to read, and always allows write
526  *
527  * Implemented by linked list of requests.  Each open file has 
528  * a ->private that also exists in this list.  New request are added
529  * to the end and may wakeup and preceding readers.
530  * New readers are added to the head.  If, on read, an item is found with
531  * CACHE_UPCALLING clear, we free it from the list.
532  *
533  */
534
535 static DEFINE_SPINLOCK(queue_lock);
536 static DEFINE_MUTEX(queue_io_mutex);
537
538 struct cache_queue {
539         struct list_head        list;
540         int                     reader; /* if 0, then request */
541 };
542 struct cache_request {
543         struct cache_queue      q;
544         struct cache_head       *item;
545         char                    * buf;
546         int                     len;
547         int                     readers;
548 };
549 struct cache_reader {
550         struct cache_queue      q;
551         int                     offset; /* if non-0, we have a refcnt on next request */
552 };
553
554 static ssize_t
555 cache_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
556 {
557         struct cache_reader *rp = filp->private_data;
558         struct cache_request *rq;
559         struct cache_detail *cd = PDE(filp->f_dentry->d_inode)->data;
560         int err;
561
562         if (count == 0)
563                 return 0;
564
565         mutex_lock(&queue_io_mutex); /* protect against multiple concurrent
566                               * readers on this file */
567  again:
568         spin_lock(&queue_lock);
569         /* need to find next request */
570         while (rp->q.list.next != &cd->queue &&
571                list_entry(rp->q.list.next, struct cache_queue, list)
572                ->reader) {
573                 struct list_head *next = rp->q.list.next;
574                 list_move(&rp->q.list, next);
575         }
576         if (rp->q.list.next == &cd->queue) {
577                 spin_unlock(&queue_lock);
578                 mutex_unlock(&queue_io_mutex);
579                 BUG_ON(rp->offset);
580                 return 0;
581         }
582         rq = container_of(rp->q.list.next, struct cache_request, q.list);
583         BUG_ON(rq->q.reader);
584         if (rp->offset == 0)
585                 rq->readers++;
586         spin_unlock(&queue_lock);
587
588         if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) {
589                 err = -EAGAIN;
590                 spin_lock(&queue_lock);
591                 list_move(&rp->q.list, &rq->q.list);
592                 spin_unlock(&queue_lock);
593         } else {
594                 if (rp->offset + count > rq->len)
595                         count = rq->len - rp->offset;
596                 err = -EFAULT;
597                 if (copy_to_user(buf, rq->buf + rp->offset, count))
598                         goto out;
599                 rp->offset += count;
600                 if (rp->offset >= rq->len) {
601                         rp->offset = 0;
602                         spin_lock(&queue_lock);
603                         list_move(&rp->q.list, &rq->q.list);
604                         spin_unlock(&queue_lock);
605                 }
606                 err = 0;
607         }
608  out:
609         if (rp->offset == 0) {
610                 /* need to release rq */
611                 spin_lock(&queue_lock);
612                 rq->readers--;
613                 if (rq->readers == 0 &&
614                     !test_bit(CACHE_PENDING, &rq->item->flags)) {
615                         list_del(&rq->q.list);
616                         spin_unlock(&queue_lock);
617                         cd->cache_put(rq->item, cd);
618                         kfree(rq->buf);
619                         kfree(rq);
620                 } else
621                         spin_unlock(&queue_lock);
622         }
623         if (err == -EAGAIN)
624                 goto again;
625         mutex_unlock(&queue_io_mutex);
626         return err ? err :  count;
627 }
628
629 static char write_buf[8192]; /* protected by queue_io_mutex */
630
631 static ssize_t
632 cache_write(struct file *filp, const char __user *buf, size_t count,
633             loff_t *ppos)
634 {
635         int err;
636         struct cache_detail *cd = PDE(filp->f_dentry->d_inode)->data;
637
638         if (count == 0)
639                 return 0;
640         if (count >= sizeof(write_buf))
641                 return -EINVAL;
642
643         mutex_lock(&queue_io_mutex);
644
645         if (copy_from_user(write_buf, buf, count)) {
646                 mutex_unlock(&queue_io_mutex);
647                 return -EFAULT;
648         }
649         write_buf[count] = '\0';
650         if (cd->cache_parse)
651                 err = cd->cache_parse(cd, write_buf, count);
652         else
653                 err = -EINVAL;
654
655         mutex_unlock(&queue_io_mutex);
656         return err ? err : count;
657 }
658
659 static DECLARE_WAIT_QUEUE_HEAD(queue_wait);
660
661 static unsigned int
662 cache_poll(struct file *filp, poll_table *wait)
663 {
664         unsigned int mask;
665         struct cache_reader *rp = filp->private_data;
666         struct cache_queue *cq;
667         struct cache_detail *cd = PDE(filp->f_dentry->d_inode)->data;
668
669         poll_wait(filp, &queue_wait, wait);
670
671         /* alway allow write */
672         mask = POLL_OUT | POLLWRNORM;
673
674         if (!rp)
675                 return mask;
676
677         spin_lock(&queue_lock);
678
679         for (cq= &rp->q; &cq->list != &cd->queue;
680              cq = list_entry(cq->list.next, struct cache_queue, list))
681                 if (!cq->reader) {
682                         mask |= POLLIN | POLLRDNORM;
683                         break;
684                 }
685         spin_unlock(&queue_lock);
686         return mask;
687 }
688
689 static int
690 cache_ioctl(struct inode *ino, struct file *filp,
691             unsigned int cmd, unsigned long arg)
692 {
693         int len = 0;
694         struct cache_reader *rp = filp->private_data;
695         struct cache_queue *cq;
696         struct cache_detail *cd = PDE(ino)->data;
697
698         if (cmd != FIONREAD || !rp)
699                 return -EINVAL;
700
701         spin_lock(&queue_lock);
702
703         /* only find the length remaining in current request,
704          * or the length of the next request
705          */
706         for (cq= &rp->q; &cq->list != &cd->queue;
707              cq = list_entry(cq->list.next, struct cache_queue, list))
708                 if (!cq->reader) {
709                         struct cache_request *cr =
710                                 container_of(cq, struct cache_request, q);
711                         len = cr->len - rp->offset;
712                         break;
713                 }
714         spin_unlock(&queue_lock);
715
716         return put_user(len, (int __user *)arg);
717 }
718
719 static int
720 cache_open(struct inode *inode, struct file *filp)
721 {
722         struct cache_reader *rp = NULL;
723
724         nonseekable_open(inode, filp);
725         if (filp->f_mode & FMODE_READ) {
726                 struct cache_detail *cd = PDE(inode)->data;
727
728                 rp = kmalloc(sizeof(*rp), GFP_KERNEL);
729                 if (!rp)
730                         return -ENOMEM;
731                 rp->offset = 0;
732                 rp->q.reader = 1;
733                 atomic_inc(&cd->readers);
734                 spin_lock(&queue_lock);
735                 list_add(&rp->q.list, &cd->queue);
736                 spin_unlock(&queue_lock);
737         }
738         filp->private_data = rp;
739         return 0;
740 }
741
742 static int
743 cache_release(struct inode *inode, struct file *filp)
744 {
745         struct cache_reader *rp = filp->private_data;
746         struct cache_detail *cd = PDE(inode)->data;
747
748         if (rp) {
749                 spin_lock(&queue_lock);
750                 if (rp->offset) {
751                         struct cache_queue *cq;
752                         for (cq= &rp->q; &cq->list != &cd->queue;
753                              cq = list_entry(cq->list.next, struct cache_queue, list))
754                                 if (!cq->reader) {
755                                         container_of(cq, struct cache_request, q)
756                                                 ->readers--;
757                                         break;
758                                 }
759                         rp->offset = 0;
760                 }
761                 list_del(&rp->q.list);
762                 spin_unlock(&queue_lock);
763
764                 filp->private_data = NULL;
765                 kfree(rp);
766
767                 cd->last_close = get_seconds();
768                 atomic_dec(&cd->readers);
769         }
770         return 0;
771 }
772
773
774
775 static struct file_operations cache_file_operations = {
776         .owner          = THIS_MODULE,
777         .llseek         = no_llseek,
778         .read           = cache_read,
779         .write          = cache_write,
780         .poll           = cache_poll,
781         .ioctl          = cache_ioctl, /* for FIONREAD */
782         .open           = cache_open,
783         .release        = cache_release,
784 };
785
786
787 static void queue_loose(struct cache_detail *detail, struct cache_head *ch)
788 {
789         struct cache_queue *cq;
790         spin_lock(&queue_lock);
791         list_for_each_entry(cq, &detail->queue, list)
792                 if (!cq->reader) {
793                         struct cache_request *cr = container_of(cq, struct cache_request, q);
794                         if (cr->item != ch)
795                                 continue;
796                         if (cr->readers != 0)
797                                 break;
798                         list_del(&cr->q.list);
799                         spin_unlock(&queue_lock);
800                         detail->cache_put(cr->item, detail);
801                         kfree(cr->buf);
802                         kfree(cr);
803                         return;
804                 }
805         spin_unlock(&queue_lock);
806 }
807
808 /*
809  * Support routines for text-based upcalls.
810  * Fields are separated by spaces.
811  * Fields are either mangled to quote space tab newline slosh with slosh
812  * or a hexified with a leading \x
813  * Record is terminated with newline.
814  *
815  */
816
817 void qword_add(char **bpp, int *lp, char *str)
818 {
819         char *bp = *bpp;
820         int len = *lp;
821         char c;
822
823         if (len < 0) return;
824
825         while ((c=*str++) && len)
826                 switch(c) {
827                 case ' ':
828                 case '\t':
829                 case '\n':
830                 case '\\':
831                         if (len >= 4) {
832                                 *bp++ = '\\';
833                                 *bp++ = '0' + ((c & 0300)>>6);
834                                 *bp++ = '0' + ((c & 0070)>>3);
835                                 *bp++ = '0' + ((c & 0007)>>0);
836                         }
837                         len -= 4;
838                         break;
839                 default:
840                         *bp++ = c;
841                         len--;
842                 }
843         if (c || len <1) len = -1;
844         else {
845                 *bp++ = ' ';
846                 len--;
847         }
848         *bpp = bp;
849         *lp = len;
850 }
851
852 void qword_addhex(char **bpp, int *lp, char *buf, int blen)
853 {
854         char *bp = *bpp;
855         int len = *lp;
856
857         if (len < 0) return;
858
859         if (len > 2) {
860                 *bp++ = '\\';
861                 *bp++ = 'x';
862                 len -= 2;
863                 while (blen && len >= 2) {
864                         unsigned char c = *buf++;
865                         *bp++ = '0' + ((c&0xf0)>>4) + (c>=0xa0)*('a'-'9'-1);
866                         *bp++ = '0' + (c&0x0f) + ((c&0x0f)>=0x0a)*('a'-'9'-1);
867                         len -= 2;
868                         blen--;
869                 }
870         }
871         if (blen || len<1) len = -1;
872         else {
873                 *bp++ = ' ';
874                 len--;
875         }
876         *bpp = bp;
877         *lp = len;
878 }
879
880 static void warn_no_listener(struct cache_detail *detail)
881 {
882         if (detail->last_warn != detail->last_close) {
883                 detail->last_warn = detail->last_close;
884                 if (detail->warn_no_listener)
885                         detail->warn_no_listener(detail);
886         }
887 }
888
889 /*
890  * register an upcall request to user-space.
891  * Each request is at most one page long.
892  */
893 static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h)
894 {
895
896         char *buf;
897         struct cache_request *crq;
898         char *bp;
899         int len;
900
901         if (detail->cache_request == NULL)
902                 return -EINVAL;
903
904         if (atomic_read(&detail->readers) == 0 &&
905             detail->last_close < get_seconds() - 30) {
906                         warn_no_listener(detail);
907                         return -EINVAL;
908         }
909
910         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
911         if (!buf)
912                 return -EAGAIN;
913
914         crq = kmalloc(sizeof (*crq), GFP_KERNEL);
915         if (!crq) {
916                 kfree(buf);
917                 return -EAGAIN;
918         }
919
920         bp = buf; len = PAGE_SIZE;
921
922         detail->cache_request(detail, h, &bp, &len);
923
924         if (len < 0) {
925                 kfree(buf);
926                 kfree(crq);
927                 return -EAGAIN;
928         }
929         crq->q.reader = 0;
930         crq->item = cache_get(h);
931         crq->buf = buf;
932         crq->len = PAGE_SIZE - len;
933         crq->readers = 0;
934         spin_lock(&queue_lock);
935         list_add_tail(&crq->q.list, &detail->queue);
936         spin_unlock(&queue_lock);
937         wake_up(&queue_wait);
938         return 0;
939 }
940
941 /*
942  * parse a message from user-space and pass it
943  * to an appropriate cache
944  * Messages are, like requests, separated into fields by
945  * spaces and dequotes as \xHEXSTRING or embedded \nnn octal
946  *
947  * Message is 
948  *   reply cachename expiry key ... content....
949  *
950  * key and content are both parsed by cache 
951  */
952
953 #define isodigit(c) (isdigit(c) && c <= '7')
954 int qword_get(char **bpp, char *dest, int bufsize)
955 {
956         /* return bytes copied, or -1 on error */
957         char *bp = *bpp;
958         int len = 0;
959
960         while (*bp == ' ') bp++;
961
962         if (bp[0] == '\\' && bp[1] == 'x') {
963                 /* HEX STRING */
964                 bp += 2;
965                 while (isxdigit(bp[0]) && isxdigit(bp[1]) && len < bufsize) {
966                         int byte = isdigit(*bp) ? *bp-'0' : toupper(*bp)-'A'+10;
967                         bp++;
968                         byte <<= 4;
969                         byte |= isdigit(*bp) ? *bp-'0' : toupper(*bp)-'A'+10;
970                         *dest++ = byte;
971                         bp++;
972                         len++;
973                 }
974         } else {
975                 /* text with \nnn octal quoting */
976                 while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) {
977                         if (*bp == '\\' &&
978                             isodigit(bp[1]) && (bp[1] <= '3') &&
979                             isodigit(bp[2]) &&
980                             isodigit(bp[3])) {
981                                 int byte = (*++bp -'0');
982                                 bp++;
983                                 byte = (byte << 3) | (*bp++ - '0');
984                                 byte = (byte << 3) | (*bp++ - '0');
985                                 *dest++ = byte;
986                                 len++;
987                         } else {
988                                 *dest++ = *bp++;
989                                 len++;
990                         }
991                 }
992         }
993
994         if (*bp != ' ' && *bp != '\n' && *bp != '\0')
995                 return -1;
996         while (*bp == ' ') bp++;
997         *bpp = bp;
998         *dest = '\0';
999         return len;
1000 }
1001
1002
1003 /*
1004  * support /proc/sunrpc/cache/$CACHENAME/content
1005  * as a seqfile.
1006  * We call ->cache_show passing NULL for the item to
1007  * get a header, then pass each real item in the cache
1008  */
1009
1010 struct handle {
1011         struct cache_detail *cd;
1012 };
1013
1014 static void *c_start(struct seq_file *m, loff_t *pos)
1015 {
1016         loff_t n = *pos;
1017         unsigned hash, entry;
1018         struct cache_head *ch;
1019         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1020         
1021
1022         read_lock(&cd->hash_lock);
1023         if (!n--)
1024                 return SEQ_START_TOKEN;
1025         hash = n >> 32;
1026         entry = n & ((1LL<<32) - 1);
1027
1028         for (ch=cd->hash_table[hash]; ch; ch=ch->next)
1029                 if (!entry--)
1030                         return ch;
1031         n &= ~((1LL<<32) - 1);
1032         do {
1033                 hash++;
1034                 n += 1LL<<32;
1035         } while(hash < cd->hash_size && 
1036                 cd->hash_table[hash]==NULL);
1037         if (hash >= cd->hash_size)
1038                 return NULL;
1039         *pos = n+1;
1040         return cd->hash_table[hash];
1041 }
1042
1043 static void *c_next(struct seq_file *m, void *p, loff_t *pos)
1044 {
1045         struct cache_head *ch = p;
1046         int hash = (*pos >> 32);
1047         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1048
1049         if (p == SEQ_START_TOKEN)
1050                 hash = 0;
1051         else if (ch->next == NULL) {
1052                 hash++;
1053                 *pos += 1LL<<32;
1054         } else {
1055                 ++*pos;
1056                 return ch->next;
1057         }
1058         *pos &= ~((1LL<<32) - 1);
1059         while (hash < cd->hash_size &&
1060                cd->hash_table[hash] == NULL) {
1061                 hash++;
1062                 *pos += 1LL<<32;
1063         }
1064         if (hash >= cd->hash_size)
1065                 return NULL;
1066         ++*pos;
1067         return cd->hash_table[hash];
1068 }
1069
1070 static void c_stop(struct seq_file *m, void *p)
1071 {
1072         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1073         read_unlock(&cd->hash_lock);
1074 }
1075
1076 static int c_show(struct seq_file *m, void *p)
1077 {
1078         struct cache_head *cp = p;
1079         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1080
1081         if (p == SEQ_START_TOKEN)
1082                 return cd->cache_show(m, cd, NULL);
1083
1084         ifdebug(CACHE)
1085                 seq_printf(m, "# expiry=%ld refcnt=%d\n",
1086                            cp->expiry_time, atomic_read(&cp->refcnt));
1087         cache_get(cp);
1088         if (cache_check(cd, cp, NULL))
1089                 /* cache_check does a cache_put on failure */
1090                 seq_printf(m, "# ");
1091         else
1092                 cache_put(cp, cd);
1093
1094         return cd->cache_show(m, cd, cp);
1095 }
1096
1097 static struct seq_operations cache_content_op = {
1098         .start  = c_start,
1099         .next   = c_next,
1100         .stop   = c_stop,
1101         .show   = c_show,
1102 };
1103
1104 static int content_open(struct inode *inode, struct file *file)
1105 {
1106         int res;
1107         struct handle *han;
1108         struct cache_detail *cd = PDE(inode)->data;
1109
1110         han = kmalloc(sizeof(*han), GFP_KERNEL);
1111         if (han == NULL)
1112                 return -ENOMEM;
1113
1114         han->cd = cd;
1115
1116         res = seq_open(file, &cache_content_op);
1117         if (res)
1118                 kfree(han);
1119         else
1120                 ((struct seq_file *)file->private_data)->private = han;
1121
1122         return res;
1123 }
1124 static int content_release(struct inode *inode, struct file *file)
1125 {
1126         struct seq_file *m = (struct seq_file *)file->private_data;
1127         struct handle *han = m->private;
1128         kfree(han);
1129         m->private = NULL;
1130         return seq_release(inode, file);
1131 }
1132
1133 static struct file_operations content_file_operations = {
1134         .open           = content_open,
1135         .read           = seq_read,
1136         .llseek         = seq_lseek,
1137         .release        = content_release,
1138 };
1139
1140 static ssize_t read_flush(struct file *file, char __user *buf,
1141                             size_t count, loff_t *ppos)
1142 {
1143         struct cache_detail *cd = PDE(file->f_dentry->d_inode)->data;
1144         char tbuf[20];
1145         unsigned long p = *ppos;
1146         int len;
1147
1148         sprintf(tbuf, "%lu\n", cd->flush_time);
1149         len = strlen(tbuf);
1150         if (p >= len)
1151                 return 0;
1152         len -= p;
1153         if (len > count) len = count;
1154         if (copy_to_user(buf, (void*)(tbuf+p), len))
1155                 len = -EFAULT;
1156         else
1157                 *ppos += len;
1158         return len;
1159 }
1160
1161 static ssize_t write_flush(struct file * file, const char __user * buf,
1162                              size_t count, loff_t *ppos)
1163 {
1164         struct cache_detail *cd = PDE(file->f_dentry->d_inode)->data;
1165         char tbuf[20];
1166         char *ep;
1167         long flushtime;
1168         if (*ppos || count > sizeof(tbuf)-1)
1169                 return -EINVAL;
1170         if (copy_from_user(tbuf, buf, count))
1171                 return -EFAULT;
1172         tbuf[count] = 0;
1173         flushtime = simple_strtoul(tbuf, &ep, 0);
1174         if (*ep && *ep != '\n')
1175                 return -EINVAL;
1176
1177         cd->flush_time = flushtime;
1178         cd->nextcheck = get_seconds();
1179         cache_flush();
1180
1181         *ppos += count;
1182         return count;
1183 }
1184
1185 static struct file_operations cache_flush_operations = {
1186         .open           = nonseekable_open,
1187         .read           = read_flush,
1188         .write          = write_flush,
1189 };