git.oblomov.eu Git - linux-2.6/blob - 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 };