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("Want update, refage=%ld, age=%ld\n", refresh_age, age);
 219                 if (!test_and_set_bit(CACHE_PENDING, &h->flags)) {
 220                         switch (cache_make_upcall(detail, h)) {
 221                         case -EINVAL:
 222                                 clear_bit(CACHE_PENDING, &h->flags);
 223                                 if (rv == -EAGAIN) {
 224                                         set_bit(CACHE_NEGATIVE, &h->flags);
 225                                         cache_fresh_unlocked(h, detail,
 226                                              cache_fresh_locked(h, get_seconds()+CACHE_NEW_EXPIRY));
 227                                         rv = -ENOENT;
 228                                 }
 229                                 break;
 230
 231                         case -EAGAIN:
 232                                 clear_bit(CACHE_PENDING, &h->flags);
 233                                 cache_revisit_request(h);
 234                                 break;
 235                         }
 236                 }
 237         }
 238
 239         if (rv == -EAGAIN)
 240                 if (cache_defer_req(rqstp, h) != 0)
 241                         rv = -ETIMEDOUT;
 242
 243         if (rv)
 244                 cache_put(h, detail);
 245         return rv;
 246 }
 247
 248 /*
 249  * caches need to be periodically cleaned.
 250  * For this we maintain a list of cache_detail and
 251  * a current pointer into that list and into the table
 252  * for that entry.
 253  *
 254  * Each time clean_cache is called it finds the next non-empty entry
 255  * in the current table and walks the list in that entry
 256  * looking for entries that can be removed.
 257  *
 258  * An entry gets removed if:
 259  * - The expiry is before current time
 260  * - The last_refresh time is before the flush_time for that cache
 261  *
 262  * later we might drop old entries with non-NEVER expiry if that table
 263  * is getting 'full' for some definition of 'full'
 264  *
 265  * The question of "how often to scan a table" is an interesting one
 266  * and is answered in part by the use of the "nextcheck" field in the
 267  * cache_detail.
 268  * When a scan of a table begins, the nextcheck field is set to a time
 269  * that is well into the future.
 270  * While scanning, if an expiry time is found that is earlier than the
 271  * current nextcheck time, nextcheck is set to that expiry time.
 272  * If the flush_time is ever set to a time earlier than the nextcheck
 273  * time, the nextcheck time is then set to that flush_time.
 274  *
 275  * A table is then only scanned if the current time is at least
 276  * the nextcheck time.
 277  *
 278  */
 279
 280 static LIST_HEAD(cache_list);
 281 static DEFINE_SPINLOCK(cache_list_lock);
 282 static struct cache_detail *current_detail;
 283 static int current_index;
 284
 285 static struct file_operations cache_file_operations;
 286 static struct file_operations content_file_operations;
 287 static struct file_operations cache_flush_operations;
 288
 289 static void do_cache_clean(struct work_struct *work);
 290 static DECLARE_DELAYED_WORK(cache_cleaner, do_cache_clean);
 291
 292 void cache_register(struct cache_detail *cd)
 293 {
 294         cd->proc_ent = proc_mkdir(cd->name, proc_net_rpc);
 295         if (cd->proc_ent) {
 296                 struct proc_dir_entry *p;
 297                 cd->proc_ent->owner = cd->owner;
 298                 cd->channel_ent = cd->content_ent = NULL;
 299
 300                 p = create_proc_entry("flush", S_IFREG|S_IRUSR|S_IWUSR,
 301                                       cd->proc_ent);
 302                 cd->flush_ent =  p;
 303                 if (p) {
 304                         p->proc_fops = &cache_flush_operations;
 305                         p->owner = cd->owner;
 306                         p->data = cd;
 307                 }
 308
 309                 if (cd->cache_request || cd->cache_parse) {
 310                         p = create_proc_entry("channel", S_IFREG|S_IRUSR|S_IWUSR,
 311                                               cd->proc_ent);
 312                         cd->channel_ent = p;
 313                         if (p) {
 314                                 p->proc_fops = &cache_file_operations;
 315                                 p->owner = cd->owner;
 316                                 p->data = cd;
 317                         }
 318                 }
 319                 if (cd->cache_show) {
 320                         p = create_proc_entry("content", S_IFREG|S_IRUSR|S_IWUSR,
 321                                               cd->proc_ent);
 322                         cd->content_ent = p;
 323                         if (p) {
 324                                 p->proc_fops = &content_file_operations;
 325                                 p->owner = cd->owner;
 326                                 p->data = cd;
 327                         }
 328                 }
 329         }
 330         rwlock_init(&cd->hash_lock);
 331         INIT_LIST_HEAD(&cd->queue);
 332         spin_lock(&cache_list_lock);
 333         cd->nextcheck = 0;
 334         cd->entries = 0;
 335         atomic_set(&cd->readers, 0);
 336         cd->last_close = 0;
 337         cd->last_warn = -1;
 338         list_add(&cd->others, &cache_list);
 339         spin_unlock(&cache_list_lock);
 340
 341         /* start the cleaning process */
 342         schedule_delayed_work(&cache_cleaner, 0);
 343 }
 344
 345 int cache_unregister(struct cache_detail *cd)
 346 {
 347         cache_purge(cd);
 348         spin_lock(&cache_list_lock);
 349         write_lock(&cd->hash_lock);
 350         if (cd->entries || atomic_read(&cd->inuse)) {
 351                 write_unlock(&cd->hash_lock);
 352                 spin_unlock(&cache_list_lock);
 353                 return -EBUSY;
 354         }
 355         if (current_detail == cd)
 356                 current_detail = NULL;
 357         list_del_init(&cd->others);
 358         write_unlock(&cd->hash_lock);
 359         spin_unlock(&cache_list_lock);
 360         if (cd->proc_ent) {
 361                 if (cd->flush_ent)
 362                         remove_proc_entry("flush", cd->proc_ent);
 363                 if (cd->channel_ent)
 364                         remove_proc_entry("channel", cd->proc_ent);
 365                 if (cd->content_ent)
 366                         remove_proc_entry("content", cd->proc_ent);
 367
 368                 cd->proc_ent = NULL;
 369                 remove_proc_entry(cd->name, proc_net_rpc);
 370         }
 371         if (list_empty(&cache_list)) {
 372                 /* module must be being unloaded so its safe to kill the worker */
 373                 cancel_delayed_work(&cache_cleaner);
 374                 flush_scheduled_work();
 375         }
 376         return 0;
 377 }
 378
 379 /* clean cache tries to find something to clean
 380  * and cleans it.
 381  * It returns 1 if it cleaned something,
 382  *            0 if it didn't find anything this time
 383  *           -1 if it fell off the end of the list.
 384  */
 385 static int cache_clean(void)
 386 {
 387         int rv = 0;
 388         struct list_head *next;
 389
 390         spin_lock(&cache_list_lock);
 391
 392         /* find a suitable table if we don't already have one */
 393         while (current_detail == NULL ||
 394             current_index >= current_detail->hash_size) {
 395                 if (current_detail)
 396                         next = current_detail->others.next;
 397                 else
 398                         next = cache_list.next;
 399                 if (next == &cache_list) {
 400                         current_detail = NULL;
 401                         spin_unlock(&cache_list_lock);
 402                         return -1;
 403                 }
 404                 current_detail = list_entry(next, struct cache_detail, others);
 405                 if (current_detail->nextcheck > get_seconds())
 406                         current_index = current_detail->hash_size;
 407                 else {
 408                         current_index = 0;
 409                         current_detail->nextcheck = get_seconds()+30*60;
 410                 }
 411         }
 412
 413         /* find a non-empty bucket in the table */
 414         while (current_detail &&
 415                current_index < current_detail->hash_size &&
 416                current_detail->hash_table[current_index] == NULL)
 417                 current_index++;
 418
 419         /* find a cleanable entry in the bucket and clean it, or set to next bucket */
 420
 421         if (current_detail && current_index < current_detail->hash_size) {
 422                 struct cache_head *ch, **cp;
 423                 struct cache_detail *d;
 424
 425                 write_lock(&current_detail->hash_lock);
 426
 427                 /* Ok, now to clean this strand */
 428
 429                 cp = & current_detail->hash_table[current_index];
 430                 ch = *cp;
 431                 for (; ch; cp= & ch->next, ch= *cp) {
 432                         if (current_detail->nextcheck > ch->expiry_time)
 433                                 current_detail->nextcheck = ch->expiry_time+1;
 434                         if (ch->expiry_time >= get_seconds()
 435                             && ch->last_refresh >= current_detail->flush_time
 436                                 )
 437                                 continue;
 438                         if (test_and_clear_bit(CACHE_PENDING, &ch->flags))
 439                                 queue_loose(current_detail, ch);
 440
 441                         if (atomic_read(&ch->ref.refcount) == 1)
 442                                 break;
 443                 }
 444                 if (ch) {
 445                         *cp = ch->next;
 446                         ch->next = NULL;
 447                         current_detail->entries--;
 448                         rv = 1;
 449                 }
 450                 write_unlock(&current_detail->hash_lock);
 451                 d = current_detail;
 452                 if (!ch)
 453                         current_index ++;
 454                 spin_unlock(&cache_list_lock);
 455                 if (ch)
 456                         cache_put(ch, d);
 457         } else
 458                 spin_unlock(&cache_list_lock);
 459
 460         return rv;
 461 }
 462
 463 /*
 464  * We want to regularly clean the cache, so we need to schedule some work ...
 465  */
 466 static void do_cache_clean(struct work_struct *work)
 467 {
 468         int delay = 5;
 469         if (cache_clean() == -1)
 470                 delay = 30*HZ;
 471
 472         if (list_empty(&cache_list))
 473                 delay = 0;
 474
 475         if (delay)
 476                 schedule_delayed_work(&cache_cleaner, delay);
 477 }
 478
 479
 480 /*
 481  * Clean all caches promptly.  This just calls cache_clean
 482  * repeatedly until we are sure that every cache has had a chance to
 483  * be fully cleaned
 484  */
 485 void cache_flush(void)
 486 {
 487         while (cache_clean() != -1)
 488                 cond_resched();
 489         while (cache_clean() != -1)
 490                 cond_resched();
 491 }
 492
 493 void cache_purge(struct cache_detail *detail)
 494 {
 495         detail->flush_time = LONG_MAX;
 496         detail->nextcheck = get_seconds();
 497         cache_flush();
 498         detail->flush_time = 1;
 499 }
 500
 501
 502
 503 /*
 504  * Deferral and Revisiting of Requests.
 505  *
 506  * If a cache lookup finds a pending entry, we
 507  * need to defer the request and revisit it later.
 508  * All deferred requests are stored in a hash table,
 509  * indexed by "struct cache_head *".
 510  * As it may be wasteful to store a whole request
 511  * structure, we allow the request to provide a
 512  * deferred form, which must contain a
 513  * 'struct cache_deferred_req'
 514  * This cache_deferred_req contains a method to allow
 515  * it to be revisited when cache info is available
 516  */
 517
 518 #define DFR_HASHSIZE    (PAGE_SIZE/sizeof(struct list_head))
 519 #define DFR_HASH(item)  ((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE)
 520
 521 #define DFR_MAX 300     /* ??? */
 522
 523 static DEFINE_SPINLOCK(cache_defer_lock);
 524 static LIST_HEAD(cache_defer_list);
 525 static struct list_head cache_defer_hash[DFR_HASHSIZE];
 526 static int cache_defer_cnt;
 527
 528 static int cache_defer_req(struct cache_req *req, struct cache_head *item)
 529 {
 530         struct cache_deferred_req *dreq;
 531         int hash = DFR_HASH(item);
 532
 533         dreq = req->defer(req);
 534         if (dreq == NULL)
 535                 return -ETIMEDOUT;
 536
 537         dreq->item = item;
 538         dreq->recv_time = get_seconds();
 539
 540         spin_lock(&cache_defer_lock);
 541
 542         list_add(&dreq->recent, &cache_defer_list);
 543
 544         if (cache_defer_hash[hash].next == NULL)
 545                 INIT_LIST_HEAD(&cache_defer_hash[hash]);
 546         list_add(&dreq->hash, &cache_defer_hash[hash]);
 547
 548         /* it is in, now maybe clean up */
 549         dreq = NULL;
 550         if (++cache_defer_cnt > DFR_MAX) {
 551                 /* too much in the cache, randomly drop
 552                  * first or last
 553                  */
 554                 if (net_random()&1)
 555                         dreq = list_entry(cache_defer_list.next,
 556                                           struct cache_deferred_req,
 557                                           recent);
 558                 else
 559                         dreq = list_entry(cache_defer_list.prev,
 560                                           struct cache_deferred_req,
 561                                           recent);
 562                 list_del(&dreq->recent);
 563                 list_del(&dreq->hash);
 564                 cache_defer_cnt--;
 565         }
 566         spin_unlock(&cache_defer_lock);
 567
 568         if (dreq) {
 569                 /* there was one too many */
 570                 dreq->revisit(dreq, 1);
 571         }
 572         if (!test_bit(CACHE_PENDING, &item->flags)) {
 573                 /* must have just been validated... */
 574                 cache_revisit_request(item);
 575         }
 576         return 0;
 577 }
 578
 579 static void cache_revisit_request(struct cache_head *item)
 580 {
 581         struct cache_deferred_req *dreq;
 582         struct list_head pending;
 583
 584         struct list_head *lp;
 585         int hash = DFR_HASH(item);
 586
 587         INIT_LIST_HEAD(&pending);
 588         spin_lock(&cache_defer_lock);
 589
 590         lp = cache_defer_hash[hash].next;
 591         if (lp) {
 592                 while (lp != &cache_defer_hash[hash]) {
 593                         dreq = list_entry(lp, struct cache_deferred_req, hash);
 594                         lp = lp->next;
 595                         if (dreq->item == item) {
 596                                 list_del(&dreq->hash);
 597                                 list_move(&dreq->recent, &pending);
 598                                 cache_defer_cnt--;
 599                         }
 600                 }
 601         }
 602         spin_unlock(&cache_defer_lock);
 603
 604         while (!list_empty(&pending)) {
 605                 dreq = list_entry(pending.next, struct cache_deferred_req, recent);
 606                 list_del_init(&dreq->recent);
 607                 dreq->revisit(dreq, 0);
 608         }
 609 }
 610
 611 void cache_clean_deferred(void *owner)
 612 {
 613         struct cache_deferred_req *dreq, *tmp;
 614         struct list_head pending;
 615
 616
 617         INIT_LIST_HEAD(&pending);
 618         spin_lock(&cache_defer_lock);
 619
 620         list_for_each_entry_safe(dreq, tmp, &cache_defer_list, recent) {
 621                 if (dreq->owner == owner) {
 622                         list_del(&dreq->hash);
 623                         list_move(&dreq->recent, &pending);
 624                         cache_defer_cnt--;
 625                 }
 626         }
 627         spin_unlock(&cache_defer_lock);
 628
 629         while (!list_empty(&pending)) {
 630                 dreq = list_entry(pending.next, struct cache_deferred_req, recent);
 631                 list_del_init(&dreq->recent);
 632                 dreq->revisit(dreq, 1);
 633         }
 634 }
 635
 636 /*
 637  * communicate with user-space
 638  *
 639  * We have a magic /proc file - /proc/sunrpc/cache
 640  * On read, you get a full request, or block
 641  * On write, an update request is processed
 642  * Poll works if anything to read, and always allows write
 643  *
 644  * Implemented by linked list of requests.  Each open file has
 645  * a ->private that also exists in this list.  New request are added
 646  * to the end and may wakeup and preceding readers.
 647  * New readers are added to the head.  If, on read, an item is found with
 648  * CACHE_UPCALLING clear, we free it from the list.
 649  *
 650  */
 651
 652 static DEFINE_SPINLOCK(queue_lock);
 653 static DEFINE_MUTEX(queue_io_mutex);
 654
 655 struct cache_queue {
 656         struct list_head        list;
 657         int                     reader; /* if 0, then request */
 658 };
 659 struct cache_request {
 660         struct cache_queue      q;
 661         struct cache_head       *item;
 662         char                    * buf;
 663         int                     len;
 664         int                     readers;
 665 };
 666 struct cache_reader {
 667         struct cache_queue      q;
 668         int                     offset; /* if non-0, we have a refcnt on next request */
 669 };
 670
 671 static ssize_t
 672 cache_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
 673 {
 674         struct cache_reader *rp = filp->private_data;
 675         struct cache_request *rq;
 676         struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;
 677         int err;
 678
 679         if (count == 0)
 680                 return 0;
 681
 682         mutex_lock(&queue_io_mutex); /* protect against multiple concurrent
 683                               * readers on this file */
 684  again:
 685         spin_lock(&queue_lock);
 686         /* need to find next request */
 687         while (rp->q.list.next != &cd->queue &&
 688                list_entry(rp->q.list.next, struct cache_queue, list)
 689                ->reader) {
 690                 struct list_head *next = rp->q.list.next;
 691                 list_move(&rp->q.list, next);
 692         }
 693         if (rp->q.list.next == &cd->queue) {
 694                 spin_unlock(&queue_lock);
 695                 mutex_unlock(&queue_io_mutex);
 696                 BUG_ON(rp->offset);
 697                 return 0;
 698         }
 699         rq = container_of(rp->q.list.next, struct cache_request, q.list);
 700         BUG_ON(rq->q.reader);
 701         if (rp->offset == 0)
 702                 rq->readers++;
 703         spin_unlock(&queue_lock);
 704
 705         if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) {
 706                 err = -EAGAIN;
 707                 spin_lock(&queue_lock);
 708                 list_move(&rp->q.list, &rq->q.list);
 709                 spin_unlock(&queue_lock);
 710         } else {
 711                 if (rp->offset + count > rq->len)
 712                         count = rq->len - rp->offset;
 713                 err = -EFAULT;
 714                 if (copy_to_user(buf, rq->buf + rp->offset, count))
 715                         goto out;
 716                 rp->offset += count;
 717                 if (rp->offset >= rq->len) {
 718                         rp->offset = 0;
 719                         spin_lock(&queue_lock);
 720                         list_move(&rp->q.list, &rq->q.list);
 721                         spin_unlock(&queue_lock);
 722                 }
 723                 err = 0;
 724         }
 725  out:
 726         if (rp->offset == 0) {
 727                 /* need to release rq */
 728                 spin_lock(&queue_lock);
 729                 rq->readers--;
 730                 if (rq->readers == 0 &&
 731                     !test_bit(CACHE_PENDING, &rq->item->flags)) {
 732                         list_del(&rq->q.list);
 733                         spin_unlock(&queue_lock);
 734                         cache_put(rq->item, cd);
 735                         kfree(rq->buf);
 736                         kfree(rq);
 737                 } else
 738                         spin_unlock(&queue_lock);
 739         }
 740         if (err == -EAGAIN)
 741                 goto again;
 742         mutex_unlock(&queue_io_mutex);
 743         return err ? err :  count;
 744 }
 745
 746 static char write_buf[8192]; /* protected by queue_io_mutex */
 747
 748 static ssize_t
 749 cache_write(struct file *filp, const char __user *buf, size_t count,
 750             loff_t *ppos)
 751 {
 752         int err;
 753         struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;
 754
 755         if (count == 0)
 756                 return 0;
 757         if (count >= sizeof(write_buf))
 758                 return -EINVAL;
 759
 760         mutex_lock(&queue_io_mutex);
 761
 762         if (copy_from_user(write_buf, buf, count)) {
 763                 mutex_unlock(&queue_io_mutex);
 764                 return -EFAULT;
 765         }
 766         write_buf[count] = '\0';
 767         if (cd->cache_parse)
 768                 err = cd->cache_parse(cd, write_buf, count);
 769         else
 770                 err = -EINVAL;
 771
 772         mutex_unlock(&queue_io_mutex);
 773         return err ? err : count;
 774 }
 775
 776 static DECLARE_WAIT_QUEUE_HEAD(queue_wait);
 777
 778 static unsigned int
 779 cache_poll(struct file *filp, poll_table *wait)
 780 {
 781         unsigned int mask;
 782         struct cache_reader *rp = filp->private_data;
 783         struct cache_queue *cq;
 784         struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;
 785
 786         poll_wait(filp, &queue_wait, wait);
 787
 788         /* alway allow write */
 789         mask = POLL_OUT | POLLWRNORM;
 790
 791         if (!rp)
 792                 return mask;
 793
 794         spin_lock(&queue_lock);
 795
 796         for (cq= &rp->q; &cq->list != &cd->queue;
 797              cq = list_entry(cq->list.next, struct cache_queue, list))
 798                 if (!cq->reader) {
 799                         mask |= POLLIN | POLLRDNORM;
 800                         break;
 801                 }
 802         spin_unlock(&queue_lock);
 803         return mask;
 804 }
 805
 806 static int
 807 cache_ioctl(struct inode *ino, struct file *filp,
 808             unsigned int cmd, unsigned long arg)
 809 {
 810         int len = 0;
 811         struct cache_reader *rp = filp->private_data;
 812         struct cache_queue *cq;
 813         struct cache_detail *cd = PDE(ino)->data;
 814
 815         if (cmd != FIONREAD || !rp)
 816                 return -EINVAL;
 817
 818         spin_lock(&queue_lock);
 819
 820         /* only find the length remaining in current request,
 821          * or the length of the next request
 822          */
 823         for (cq= &rp->q; &cq->list != &cd->queue;
 824              cq = list_entry(cq->list.next, struct cache_queue, list))
 825                 if (!cq->reader) {
 826                         struct cache_request *cr =
 827                                 container_of(cq, struct cache_request, q);
 828                         len = cr->len - rp->offset;
 829                         break;
 830                 }
 831         spin_unlock(&queue_lock);
 832
 833         return put_user(len, (int __user *)arg);
 834 }
 835
 836 static int
 837 cache_open(struct inode *inode, struct file *filp)
 838 {
 839         struct cache_reader *rp = NULL;
 840
 841         nonseekable_open(inode, filp);
 842         if (filp->f_mode & FMODE_READ) {
 843                 struct cache_detail *cd = PDE(inode)->data;
 844
 845                 rp = kmalloc(sizeof(*rp), GFP_KERNEL);
 846                 if (!rp)
 847                         return -ENOMEM;
 848                 rp->offset = 0;
 849                 rp->q.reader = 1;
 850                 atomic_inc(&cd->readers);
 851                 spin_lock(&queue_lock);
 852                 list_add(&rp->q.list, &cd->queue);
 853                 spin_unlock(&queue_lock);
 854         }
 855         filp->private_data = rp;
 856         return 0;
 857 }
 858
 859 static int
 860 cache_release(struct inode *inode, struct file *filp)
 861 {
 862         struct cache_reader *rp = filp->private_data;
 863         struct cache_detail *cd = PDE(inode)->data;
 864
 865         if (rp) {
 866                 spin_lock(&queue_lock);
 867                 if (rp->offset) {
 868                         struct cache_queue *cq;
 869                         for (cq= &rp->q; &cq->list != &cd->queue;
 870                              cq = list_entry(cq->list.next, struct cache_queue, list))
 871                                 if (!cq->reader) {
 872                                         container_of(cq, struct cache_request, q)
 873                                                 ->readers--;
 874                                         break;
 875                                 }
 876                         rp->offset = 0;
 877                 }
 878                 list_del(&rp->q.list);
 879                 spin_unlock(&queue_lock);
 880
 881                 filp->private_data = NULL;
 882                 kfree(rp);
 883
 884                 cd->last_close = get_seconds();
 885                 atomic_dec(&cd->readers);
 886         }
 887         return 0;
 888 }
 889
 890
 891
 892 static struct file_operations cache_file_operations = {
 893         .owner          = THIS_MODULE,
 894         .llseek         = no_llseek,
 895         .read           = cache_read,
 896         .write          = cache_write,
 897         .poll           = cache_poll,
 898         .ioctl          = cache_ioctl, /* for FIONREAD */
 899         .open           = cache_open,
 900         .release        = cache_release,
 901 };
 902
 903
 904 static void queue_loose(struct cache_detail *detail, struct cache_head *ch)
 905 {
 906         struct cache_queue *cq;
 907         spin_lock(&queue_lock);
 908         list_for_each_entry(cq, &detail->queue, list)
 909                 if (!cq->reader) {
 910                         struct cache_request *cr = container_of(cq, struct cache_request, q);
 911                         if (cr->item != ch)
 912                                 continue;
 913                         if (cr->readers != 0)
 914                                 continue;
 915                         list_del(&cr->q.list);
 916                         spin_unlock(&queue_lock);
 917                         cache_put(cr->item, detail);
 918                         kfree(cr->buf);
 919                         kfree(cr);
 920                         return;
 921                 }
 922         spin_unlock(&queue_lock);
 923 }
 924
 925 /*
 926  * Support routines for text-based upcalls.
 927  * Fields are separated by spaces.
 928  * Fields are either mangled to quote space tab newline slosh with slosh
 929  * or a hexified with a leading \x
 930  * Record is terminated with newline.
 931  *
 932  */
 933
 934 void qword_add(char **bpp, int *lp, char *str)
 935 {
 936         char *bp = *bpp;
 937         int len = *lp;
 938         char c;
 939
 940         if (len < 0) return;
 941
 942         while ((c=*str++) && len)
 943                 switch(c) {
 944                 case ' ':
 945                 case '\t':
 946                 case '\n':
 947                 case '\\':
 948                         if (len >= 4) {
 949                                 *bp++ = '\\';
 950                                 *bp++ = '0' + ((c & 0300)>>6);
 951                                 *bp++ = '0' + ((c & 0070)>>3);
 952                                 *bp++ = '0' + ((c & 0007)>>0);
 953                         }
 954                         len -= 4;
 955                         break;
 956                 default:
 957                         *bp++ = c;
 958                         len--;
 959                 }
 960         if (c || len <1) len = -1;
 961         else {
 962                 *bp++ = ' ';
 963                 len--;
 964         }
 965         *bpp = bp;
 966         *lp = len;
 967 }
 968
 969 void qword_addhex(char **bpp, int *lp, char *buf, int blen)
 970 {
 971         char *bp = *bpp;
 972         int len = *lp;
 973
 974         if (len < 0) return;
 975
 976         if (len > 2) {
 977                 *bp++ = '\\';
 978                 *bp++ = 'x';
 979                 len -= 2;
 980                 while (blen && len >= 2) {
 981                         unsigned char c = *buf++;
 982                         *bp++ = '0' + ((c&0xf0)>>4) + (c>=0xa0)*('a'-'9'-1);
 983                         *bp++ = '0' + (c&0x0f) + ((c&0x0f)>=0x0a)*('a'-'9'-1);
 984                         len -= 2;
 985                         blen--;
 986                 }
 987         }
 988         if (blen || len<1) len = -1;
 989         else {
 990                 *bp++ = ' ';
 991                 len--;
 992         }
 993         *bpp = bp;
 994         *lp = len;
 995 }
 996
 997 static void warn_no_listener(struct cache_detail *detail)
 998 {
 999         if (detail->last_warn != detail->last_close) {
1000                 detail->last_warn = detail->last_close;
1001                 if (detail->warn_no_listener)
1002                         detail->warn_no_listener(detail);
1003         }
1004 }
1005
1006 /*
1007  * register an upcall request to user-space.
1008  * Each request is at most one page long.
1009  */
1010 static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h)
1011 {
1012
1013         char *buf;
1014         struct cache_request *crq;
1015         char *bp;
1016         int len;
1017
1018         if (detail->cache_request == NULL)
1019                 return -EINVAL;
1020
1021         if (atomic_read(&detail->readers) == 0 &&
1022             detail->last_close < get_seconds() - 30) {
1023                         warn_no_listener(detail);
1024                         return -EINVAL;
1025         }
1026
1027         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
1028         if (!buf)
1029                 return -EAGAIN;
1030
1031         crq = kmalloc(sizeof (*crq), GFP_KERNEL);
1032         if (!crq) {
1033                 kfree(buf);
1034                 return -EAGAIN;
1035         }
1036
1037         bp = buf; len = PAGE_SIZE;
1038
1039         detail->cache_request(detail, h, &bp, &len);
1040
1041         if (len < 0) {
1042                 kfree(buf);
1043                 kfree(crq);
1044                 return -EAGAIN;
1045         }
1046         crq->q.reader = 0;
1047         crq->item = cache_get(h);
1048         crq->buf = buf;
1049         crq->len = PAGE_SIZE - len;
1050         crq->readers = 0;
1051         spin_lock(&queue_lock);
1052         list_add_tail(&crq->q.list, &detail->queue);
1053         spin_unlock(&queue_lock);
1054         wake_up(&queue_wait);
1055         return 0;
1056 }
1057
1058 /*
1059  * parse a message from user-space and pass it
1060  * to an appropriate cache
1061  * Messages are, like requests, separated into fields by
1062  * spaces and dequotes as \xHEXSTRING or embedded \nnn octal
1063  *
1064  * Message is
1065  *   reply cachename expiry key ... content....
1066  *
1067  * key and content are both parsed by cache
1068  */
1069
1070 #define isodigit(c) (isdigit(c) && c <= '7')
1071 int qword_get(char **bpp, char *dest, int bufsize)
1072 {
1073         /* return bytes copied, or -1 on error */
1074         char *bp = *bpp;
1075         int len = 0;
1076
1077         while (*bp == ' ') bp++;
1078
1079         if (bp[0] == '\\' && bp[1] == 'x') {
1080                 /* HEX STRING */
1081                 bp += 2;
1082                 while (isxdigit(bp[0]) && isxdigit(bp[1]) && len < bufsize) {
1083                         int byte = isdigit(*bp) ? *bp-'0' : toupper(*bp)-'A'+10;
1084                         bp++;
1085                         byte <<= 4;
1086                         byte |= isdigit(*bp) ? *bp-'0' : toupper(*bp)-'A'+10;
1087                         *dest++ = byte;
1088                         bp++;
1089                         len++;
1090                 }
1091         } else {
1092                 /* text with \nnn octal quoting */
1093                 while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) {
1094                         if (*bp == '\\' &&
1095                             isodigit(bp[1]) && (bp[1] <= '3') &&
1096                             isodigit(bp[2]) &&
1097                             isodigit(bp[3])) {
1098                                 int byte = (*++bp -'0');
1099                                 bp++;
1100                                 byte = (byte << 3) | (*bp++ - '0');
1101                                 byte = (byte << 3) | (*bp++ - '0');
1102                                 *dest++ = byte;
1103                                 len++;
1104                         } else {
1105                                 *dest++ = *bp++;
1106                                 len++;
1107                         }
1108                 }
1109         }
1110
1111         if (*bp != ' ' && *bp != '\n' && *bp != '\0')
1112                 return -1;
1113         while (*bp == ' ') bp++;
1114         *bpp = bp;
1115         *dest = '\0';
1116         return len;
1117 }
1118
1119
1120 /*
1121  * support /proc/sunrpc/cache/$CACHENAME/content
1122  * as a seqfile.
1123  * We call ->cache_show passing NULL for the item to
1124  * get a header, then pass each real item in the cache
1125  */
1126
1127 struct handle {
1128         struct cache_detail *cd;
1129 };
1130
1131 static void *c_start(struct seq_file *m, loff_t *pos)
1132 {
1133         loff_t n = *pos;
1134         unsigned hash, entry;
1135         struct cache_head *ch;
1136         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1137
1138
1139         read_lock(&cd->hash_lock);
1140         if (!n--)
1141                 return SEQ_START_TOKEN;
1142         hash = n >> 32;
1143         entry = n & ((1LL<<32) - 1);
1144
1145         for (ch=cd->hash_table[hash]; ch; ch=ch->next)
1146                 if (!entry--)
1147                         return ch;
1148         n &= ~((1LL<<32) - 1);
1149         do {
1150                 hash++;
1151                 n += 1LL<<32;
1152         } while(hash < cd->hash_size &&
1153                 cd->hash_table[hash]==NULL);
1154         if (hash >= cd->hash_size)
1155                 return NULL;
1156         *pos = n+1;
1157         return cd->hash_table[hash];
1158 }
1159
1160 static void *c_next(struct seq_file *m, void *p, loff_t *pos)
1161 {
1162         struct cache_head *ch = p;
1163         int hash = (*pos >> 32);
1164         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1165
1166         if (p == SEQ_START_TOKEN)
1167                 hash = 0;
1168         else if (ch->next == NULL) {
1169                 hash++;
1170                 *pos += 1LL<<32;
1171         } else {
1172                 ++*pos;
1173                 return ch->next;
1174         }
1175         *pos &= ~((1LL<<32) - 1);
1176         while (hash < cd->hash_size &&
1177                cd->hash_table[hash] == NULL) {
1178                 hash++;
1179                 *pos += 1LL<<32;
1180         }
1181         if (hash >= cd->hash_size)
1182                 return NULL;
1183         ++*pos;
1184         return cd->hash_table[hash];
1185 }
1186
1187 static void c_stop(struct seq_file *m, void *p)
1188 {
1189         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1190         read_unlock(&cd->hash_lock);
1191 }
1192
1193 static int c_show(struct seq_file *m, void *p)
1194 {
1195         struct cache_head *cp = p;
1196         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1197
1198         if (p == SEQ_START_TOKEN)
1199                 return cd->cache_show(m, cd, NULL);
1200
1201         ifdebug(CACHE)
1202                 seq_printf(m, "# expiry=%ld refcnt=%d flags=%lx\n",
1203                            cp->expiry_time, atomic_read(&cp->ref.refcount), cp->flags);
1204         cache_get(cp);
1205         if (cache_check(cd, cp, NULL))
1206                 /* cache_check does a cache_put on failure */
1207                 seq_printf(m, "# ");
1208         else
1209                 cache_put(cp, cd);
1210
1211         return cd->cache_show(m, cd, cp);
1212 }
1213
1214 static struct seq_operations cache_content_op = {
1215         .start  = c_start,
1216         .next   = c_next,
1217         .stop   = c_stop,
1218         .show   = c_show,
1219 };
1220
1221 static int content_open(struct inode *inode, struct file *file)
1222 {
1223         int res;
1224         struct handle *han;
1225         struct cache_detail *cd = PDE(inode)->data;
1226
1227         han = kmalloc(sizeof(*han), GFP_KERNEL);
1228         if (han == NULL)
1229                 return -ENOMEM;
1230
1231         han->cd = cd;
1232
1233         res = seq_open(file, &cache_content_op);
1234         if (res)
1235                 kfree(han);
1236         else
1237                 ((struct seq_file *)file->private_data)->private = han;
1238
1239         return res;
1240 }
1241 static int content_release(struct inode *inode, struct file *file)
1242 {
1243         struct seq_file *m = (struct seq_file *)file->private_data;
1244         struct handle *han = m->private;
1245         kfree(han);
1246         m->private = NULL;
1247         return seq_release(inode, file);
1248 }
1249
1250 static struct file_operations content_file_operations = {
1251         .open           = content_open,
1252         .read           = seq_read,
1253         .llseek         = seq_lseek,
1254         .release        = content_release,
1255 };
1256
1257 static ssize_t read_flush(struct file *file, char __user *buf,
1258                             size_t count, loff_t *ppos)
1259 {
1260         struct cache_detail *cd = PDE(file->f_path.dentry->d_inode)->data;
1261         char tbuf[20];
1262         unsigned long p = *ppos;
1263         int len;
1264
1265         sprintf(tbuf, "%lu\n", cd->flush_time);
1266         len = strlen(tbuf);
1267         if (p >= len)
1268                 return 0;
1269         len -= p;
1270         if (len > count) len = count;
1271         if (copy_to_user(buf, (void*)(tbuf+p), len))
1272                 len = -EFAULT;
1273         else
1274                 *ppos += len;
1275         return len;
1276 }
1277
1278 static ssize_t write_flush(struct file * file, const char __user * buf,
1279                              size_t count, loff_t *ppos)
1280 {
1281         struct cache_detail *cd = PDE(file->f_path.dentry->d_inode)->data;
1282         char tbuf[20];
1283         char *ep;
1284         long flushtime;
1285         if (*ppos || count > sizeof(tbuf)-1)
1286                 return -EINVAL;
1287         if (copy_from_user(tbuf, buf, count))
1288                 return -EFAULT;
1289         tbuf[count] = 0;
1290         flushtime = simple_strtoul(tbuf, &ep, 0);
1291         if (*ep && *ep != '\n')
1292                 return -EINVAL;
1293
1294         cd->flush_time = flushtime;
1295         cd->nextcheck = get_seconds();
1296         cache_flush();
1297
1298         *ppos += count;
1299         return count;
1300 }
1301
1302 static struct file_operations cache_flush_operations = {
1303         .open           = nonseekable_open,
1304         .read           = read_flush,
1305         .write          = write_flush,
1306 };