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   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_GPL(sunrpc_cache_lookup);
 102
 103
 104 static void cache_dequeue(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                 cache_dequeue(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_GPL(sunrpc_cache_update);
 177
 178 static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h);
 179
 180 static inline int cache_is_valid(struct cache_detail *detail, struct cache_head *h)
 181 {
 182         if (!test_bit(CACHE_VALID, &h->flags) ||
 183             h->expiry_time < get_seconds())
 184                 return -EAGAIN;
 185         else if (detail->flush_time > h->last_refresh)
 186                 return -EAGAIN;
 187         else {
 188                 /* entry is valid */
 189                 if (test_bit(CACHE_NEGATIVE, &h->flags))
 190                         return -ENOENT;
 191                 else
 192                         return 0;
 193         }
 194 }
 195 /*
 196  * This is the generic cache management routine for all
 197  * the authentication caches.
 198  * It checks the currency of a cache item and will (later)
 199  * initiate an upcall to fill it if needed.
 200  *
 201  *
 202  * Returns 0 if the cache_head can be used, or cache_puts it and returns
 203  * -EAGAIN if upcall is pending and request has been queued
 204  * -ETIMEDOUT if upcall failed or request could not be queue or
 205  *           upcall completed but item is still invalid (implying that
 206  *           the cache item has been replaced with a newer one).
 207  * -ENOENT if cache entry was negative
 208  */
 209 int cache_check(struct cache_detail *detail,
 210                     struct cache_head *h, struct cache_req *rqstp)
 211 {
 212         int rv;
 213         long refresh_age, age;
 214
 215         /* First decide return status as best we can */
 216         rv = cache_is_valid(detail, h);
 217
 218         /* now see if we want to start an upcall */
 219         refresh_age = (h->expiry_time - h->last_refresh);
 220         age = get_seconds() - h->last_refresh;
 221
 222         if (rqstp == NULL) {
 223                 if (rv == -EAGAIN)
 224                         rv = -ENOENT;
 225         } else if (rv == -EAGAIN || age > refresh_age/2) {
 226                 dprintk("RPC:       Want update, refage=%ld, age=%ld\n",
 227                                 refresh_age, age);
 228                 if (!test_and_set_bit(CACHE_PENDING, &h->flags)) {
 229                         switch (cache_make_upcall(detail, h)) {
 230                         case -EINVAL:
 231                                 clear_bit(CACHE_PENDING, &h->flags);
 232                                 cache_revisit_request(h);
 233                                 if (rv == -EAGAIN) {
 234                                         set_bit(CACHE_NEGATIVE, &h->flags);
 235                                         cache_fresh_unlocked(h, detail,
 236                                              cache_fresh_locked(h, get_seconds()+CACHE_NEW_EXPIRY));
 237                                         rv = -ENOENT;
 238                                 }
 239                                 break;
 240
 241                         case -EAGAIN:
 242                                 clear_bit(CACHE_PENDING, &h->flags);
 243                                 cache_revisit_request(h);
 244                                 break;
 245                         }
 246                 }
 247         }
 248
 249         if (rv == -EAGAIN) {
 250                 if (cache_defer_req(rqstp, h) == 0) {
 251                         /* Request is not deferred */
 252                         rv = cache_is_valid(detail, h);
 253                         if (rv == -EAGAIN)
 254                                 rv = -ETIMEDOUT;
 255                 }
 256         }
 257         if (rv)
 258                 cache_put(h, detail);
 259         return rv;
 260 }
 261 EXPORT_SYMBOL_GPL(cache_check);
 262
 263 /*
 264  * caches need to be periodically cleaned.
 265  * For this we maintain a list of cache_detail and
 266  * a current pointer into that list and into the table
 267  * for that entry.
 268  *
 269  * Each time clean_cache is called it finds the next non-empty entry
 270  * in the current table and walks the list in that entry
 271  * looking for entries that can be removed.
 272  *
 273  * An entry gets removed if:
 274  * - The expiry is before current time
 275  * - The last_refresh time is before the flush_time for that cache
 276  *
 277  * later we might drop old entries with non-NEVER expiry if that table
 278  * is getting 'full' for some definition of 'full'
 279  *
 280  * The question of "how often to scan a table" is an interesting one
 281  * and is answered in part by the use of the "nextcheck" field in the
 282  * cache_detail.
 283  * When a scan of a table begins, the nextcheck field is set to a time
 284  * that is well into the future.
 285  * While scanning, if an expiry time is found that is earlier than the
 286  * current nextcheck time, nextcheck is set to that expiry time.
 287  * If the flush_time is ever set to a time earlier than the nextcheck
 288  * time, the nextcheck time is then set to that flush_time.
 289  *
 290  * A table is then only scanned if the current time is at least
 291  * the nextcheck time.
 292  *
 293  */
 294
 295 static LIST_HEAD(cache_list);
 296 static DEFINE_SPINLOCK(cache_list_lock);
 297 static struct cache_detail *current_detail;
 298 static int current_index;
 299
 300 static const struct file_operations cache_file_operations;
 301 static const struct file_operations content_file_operations;
 302 static const struct file_operations cache_flush_operations;
 303
 304 static void do_cache_clean(struct work_struct *work);
 305 static DECLARE_DELAYED_WORK(cache_cleaner, do_cache_clean);
 306
 307 static void remove_cache_proc_entries(struct cache_detail *cd)
 308 {
 309         if (cd->proc_ent == NULL)
 310                 return;
 311         if (cd->flush_ent)
 312                 remove_proc_entry("flush", cd->proc_ent);
 313         if (cd->channel_ent)
 314                 remove_proc_entry("channel", cd->proc_ent);
 315         if (cd->content_ent)
 316                 remove_proc_entry("content", cd->proc_ent);
 317         cd->proc_ent = NULL;
 318         remove_proc_entry(cd->name, proc_net_rpc);
 319 }
 320
 321 #ifdef CONFIG_PROC_FS
 322 static int create_cache_proc_entries(struct cache_detail *cd)
 323 {
 324         struct proc_dir_entry *p;
 325
 326         cd->proc_ent = proc_mkdir(cd->name, proc_net_rpc);
 327         if (cd->proc_ent == NULL)
 328                 goto out_nomem;
 329         cd->channel_ent = cd->content_ent = NULL;
 330
 331         p = proc_create_data("flush", S_IFREG|S_IRUSR|S_IWUSR,
 332                              cd->proc_ent, &cache_flush_operations, cd);
 333         cd->flush_ent = p;
 334         if (p == NULL)
 335                 goto out_nomem;
 336
 337         if (cd->cache_request || cd->cache_parse) {
 338                 p = proc_create_data("channel", S_IFREG|S_IRUSR|S_IWUSR,
 339                                      cd->proc_ent, &cache_file_operations, cd);
 340                 cd->channel_ent = p;
 341                 if (p == NULL)
 342                         goto out_nomem;
 343         }
 344         if (cd->cache_show) {
 345                 p = proc_create_data("content", S_IFREG|S_IRUSR|S_IWUSR,
 346                                 cd->proc_ent, &content_file_operations, cd);
 347                 cd->content_ent = p;
 348                 if (p == NULL)
 349                         goto out_nomem;
 350         }
 351         return 0;
 352 out_nomem:
 353         remove_cache_proc_entries(cd);
 354         return -ENOMEM;
 355 }
 356 #else /* CONFIG_PROC_FS */
 357 static int create_cache_proc_entries(struct cache_detail *cd)
 358 {
 359         return 0;
 360 }
 361 #endif
 362
 363 int cache_register(struct cache_detail *cd)
 364 {
 365         int ret;
 366
 367         ret = create_cache_proc_entries(cd);
 368         if (ret)
 369                 return ret;
 370         rwlock_init(&cd->hash_lock);
 371         INIT_LIST_HEAD(&cd->queue);
 372         spin_lock(&cache_list_lock);
 373         cd->nextcheck = 0;
 374         cd->entries = 0;
 375         atomic_set(&cd->readers, 0);
 376         cd->last_close = 0;
 377         cd->last_warn = -1;
 378         list_add(&cd->others, &cache_list);
 379         spin_unlock(&cache_list_lock);
 380
 381         /* start the cleaning process */
 382         schedule_delayed_work(&cache_cleaner, 0);
 383         return 0;
 384 }
 385 EXPORT_SYMBOL_GPL(cache_register);
 386
 387 void cache_unregister(struct cache_detail *cd)
 388 {
 389         cache_purge(cd);
 390         spin_lock(&cache_list_lock);
 391         write_lock(&cd->hash_lock);
 392         if (cd->entries || atomic_read(&cd->inuse)) {
 393                 write_unlock(&cd->hash_lock);
 394                 spin_unlock(&cache_list_lock);
 395                 goto out;
 396         }
 397         if (current_detail == cd)
 398                 current_detail = NULL;
 399         list_del_init(&cd->others);
 400         write_unlock(&cd->hash_lock);
 401         spin_unlock(&cache_list_lock);
 402         remove_cache_proc_entries(cd);
 403         if (list_empty(&cache_list)) {
 404                 /* module must be being unloaded so its safe to kill the worker */
 405                 cancel_delayed_work_sync(&cache_cleaner);
 406         }
 407         return;
 408 out:
 409         printk(KERN_ERR "nfsd: failed to unregister %s cache\n", cd->name);
 410 }
 411 EXPORT_SYMBOL_GPL(cache_unregister);
 412
 413 /* clean cache tries to find something to clean
 414  * and cleans it.
 415  * It returns 1 if it cleaned something,
 416  *            0 if it didn't find anything this time
 417  *           -1 if it fell off the end of the list.
 418  */
 419 static int cache_clean(void)
 420 {
 421         int rv = 0;
 422         struct list_head *next;
 423
 424         spin_lock(&cache_list_lock);
 425
 426         /* find a suitable table if we don't already have one */
 427         while (current_detail == NULL ||
 428             current_index >= current_detail->hash_size) {
 429                 if (current_detail)
 430                         next = current_detail->others.next;
 431                 else
 432                         next = cache_list.next;
 433                 if (next == &cache_list) {
 434                         current_detail = NULL;
 435                         spin_unlock(&cache_list_lock);
 436                         return -1;
 437                 }
 438                 current_detail = list_entry(next, struct cache_detail, others);
 439                 if (current_detail->nextcheck > get_seconds())
 440                         current_index = current_detail->hash_size;
 441                 else {
 442                         current_index = 0;
 443                         current_detail->nextcheck = get_seconds()+30*60;
 444                 }
 445         }
 446
 447         /* find a non-empty bucket in the table */
 448         while (current_detail &&
 449                current_index < current_detail->hash_size &&
 450                current_detail->hash_table[current_index] == NULL)
 451                 current_index++;
 452
 453         /* find a cleanable entry in the bucket and clean it, or set to next bucket */
 454
 455         if (current_detail && current_index < current_detail->hash_size) {
 456                 struct cache_head *ch, **cp;
 457                 struct cache_detail *d;
 458
 459                 write_lock(&current_detail->hash_lock);
 460
 461                 /* Ok, now to clean this strand */
 462
 463                 cp = & current_detail->hash_table[current_index];
 464                 ch = *cp;
 465                 for (; ch; cp= & ch->next, ch= *cp) {
 466                         if (current_detail->nextcheck > ch->expiry_time)
 467                                 current_detail->nextcheck = ch->expiry_time+1;
 468                         if (ch->expiry_time >= get_seconds()
 469                             && ch->last_refresh >= current_detail->flush_time
 470                                 )
 471                                 continue;
 472                         if (test_and_clear_bit(CACHE_PENDING, &ch->flags))
 473                                 cache_dequeue(current_detail, ch);
 474
 475                         if (atomic_read(&ch->ref.refcount) == 1)
 476                                 break;
 477                 }
 478                 if (ch) {
 479                         *cp = ch->next;
 480                         ch->next = NULL;
 481                         current_detail->entries--;
 482                         rv = 1;
 483                 }
 484                 write_unlock(&current_detail->hash_lock);
 485                 d = current_detail;
 486                 if (!ch)
 487                         current_index ++;
 488                 spin_unlock(&cache_list_lock);
 489                 if (ch) {
 490                         cache_revisit_request(ch);
 491                         cache_put(ch, d);
 492                 }
 493         } else
 494                 spin_unlock(&cache_list_lock);
 495
 496         return rv;
 497 }
 498
 499 /*
 500  * We want to regularly clean the cache, so we need to schedule some work ...
 501  */
 502 static void do_cache_clean(struct work_struct *work)
 503 {
 504         int delay = 5;
 505         if (cache_clean() == -1)
 506                 delay = round_jiffies_relative(30*HZ);
 507
 508         if (list_empty(&cache_list))
 509                 delay = 0;
 510
 511         if (delay)
 512                 schedule_delayed_work(&cache_cleaner, delay);
 513 }
 514
 515
 516 /*
 517  * Clean all caches promptly.  This just calls cache_clean
 518  * repeatedly until we are sure that every cache has had a chance to
 519  * be fully cleaned
 520  */
 521 void cache_flush(void)
 522 {
 523         while (cache_clean() != -1)
 524                 cond_resched();
 525         while (cache_clean() != -1)
 526                 cond_resched();
 527 }
 528 EXPORT_SYMBOL_GPL(cache_flush);
 529
 530 void cache_purge(struct cache_detail *detail)
 531 {
 532         detail->flush_time = LONG_MAX;
 533         detail->nextcheck = get_seconds();
 534         cache_flush();
 535         detail->flush_time = 1;
 536 }
 537 EXPORT_SYMBOL_GPL(cache_purge);
 538
 539
 540 /*
 541  * Deferral and Revisiting of Requests.
 542  *
 543  * If a cache lookup finds a pending entry, we
 544  * need to defer the request and revisit it later.
 545  * All deferred requests are stored in a hash table,
 546  * indexed by "struct cache_head *".
 547  * As it may be wasteful to store a whole request
 548  * structure, we allow the request to provide a
 549  * deferred form, which must contain a
 550  * 'struct cache_deferred_req'
 551  * This cache_deferred_req contains a method to allow
 552  * it to be revisited when cache info is available
 553  */
 554
 555 #define DFR_HASHSIZE    (PAGE_SIZE/sizeof(struct list_head))
 556 #define DFR_HASH(item)  ((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE)
 557
 558 #define DFR_MAX 300     /* ??? */
 559
 560 static DEFINE_SPINLOCK(cache_defer_lock);
 561 static LIST_HEAD(cache_defer_list);
 562 static struct list_head cache_defer_hash[DFR_HASHSIZE];
 563 static int cache_defer_cnt;
 564
 565 static int cache_defer_req(struct cache_req *req, struct cache_head *item)
 566 {
 567         struct cache_deferred_req *dreq;
 568         int hash = DFR_HASH(item);
 569
 570         if (cache_defer_cnt >= DFR_MAX) {
 571                 /* too much in the cache, randomly drop this one,
 572                  * or continue and drop the oldest below
 573                  */
 574                 if (net_random()&1)
 575                         return 0;
 576         }
 577         dreq = req->defer(req);
 578         if (dreq == NULL)
 579                 return 0;
 580
 581         dreq->item = item;
 582
 583         spin_lock(&cache_defer_lock);
 584
 585         list_add(&dreq->recent, &cache_defer_list);
 586
 587         if (cache_defer_hash[hash].next == NULL)
 588                 INIT_LIST_HEAD(&cache_defer_hash[hash]);
 589         list_add(&dreq->hash, &cache_defer_hash[hash]);
 590
 591         /* it is in, now maybe clean up */
 592         dreq = NULL;
 593         if (++cache_defer_cnt > DFR_MAX) {
 594                 dreq = list_entry(cache_defer_list.prev,
 595                                   struct cache_deferred_req, recent);
 596                 list_del(&dreq->recent);
 597                 list_del(&dreq->hash);
 598                 cache_defer_cnt--;
 599         }
 600         spin_unlock(&cache_defer_lock);
 601
 602         if (dreq) {
 603                 /* there was one too many */
 604                 dreq->revisit(dreq, 1);
 605         }
 606         if (!test_bit(CACHE_PENDING, &item->flags)) {
 607                 /* must have just been validated... */
 608                 cache_revisit_request(item);
 609                 return 0;
 610         }
 611         return 1;
 612 }
 613
 614 static void cache_revisit_request(struct cache_head *item)
 615 {
 616         struct cache_deferred_req *dreq;
 617         struct list_head pending;
 618
 619         struct list_head *lp;
 620         int hash = DFR_HASH(item);
 621
 622         INIT_LIST_HEAD(&pending);
 623         spin_lock(&cache_defer_lock);
 624
 625         lp = cache_defer_hash[hash].next;
 626         if (lp) {
 627                 while (lp != &cache_defer_hash[hash]) {
 628                         dreq = list_entry(lp, struct cache_deferred_req, hash);
 629                         lp = lp->next;
 630                         if (dreq->item == item) {
 631                                 list_del(&dreq->hash);
 632                                 list_move(&dreq->recent, &pending);
 633                                 cache_defer_cnt--;
 634                         }
 635                 }
 636         }
 637         spin_unlock(&cache_defer_lock);
 638
 639         while (!list_empty(&pending)) {
 640                 dreq = list_entry(pending.next, struct cache_deferred_req, recent);
 641                 list_del_init(&dreq->recent);
 642                 dreq->revisit(dreq, 0);
 643         }
 644 }
 645
 646 void cache_clean_deferred(void *owner)
 647 {
 648         struct cache_deferred_req *dreq, *tmp;
 649         struct list_head pending;
 650
 651
 652         INIT_LIST_HEAD(&pending);
 653         spin_lock(&cache_defer_lock);
 654
 655         list_for_each_entry_safe(dreq, tmp, &cache_defer_list, recent) {
 656                 if (dreq->owner == owner) {
 657                         list_del(&dreq->hash);
 658                         list_move(&dreq->recent, &pending);
 659                         cache_defer_cnt--;
 660                 }
 661         }
 662         spin_unlock(&cache_defer_lock);
 663
 664         while (!list_empty(&pending)) {
 665                 dreq = list_entry(pending.next, struct cache_deferred_req, recent);
 666                 list_del_init(&dreq->recent);
 667                 dreq->revisit(dreq, 1);
 668         }
 669 }
 670
 671 /*
 672  * communicate with user-space
 673  *
 674  * We have a magic /proc file - /proc/sunrpc/<cachename>/channel.
 675  * On read, you get a full request, or block.
 676  * On write, an update request is processed.
 677  * Poll works if anything to read, and always allows write.
 678  *
 679  * Implemented by linked list of requests.  Each open file has
 680  * a ->private that also exists in this list.  New requests are added
 681  * to the end and may wakeup and preceding readers.
 682  * New readers are added to the head.  If, on read, an item is found with
 683  * CACHE_UPCALLING clear, we free it from the list.
 684  *
 685  */
 686
 687 static DEFINE_SPINLOCK(queue_lock);
 688 static DEFINE_MUTEX(queue_io_mutex);
 689
 690 struct cache_queue {
 691         struct list_head        list;
 692         int                     reader; /* if 0, then request */
 693 };
 694 struct cache_request {
 695         struct cache_queue      q;
 696         struct cache_head       *item;
 697         char                    * buf;
 698         int                     len;
 699         int                     readers;
 700 };
 701 struct cache_reader {
 702         struct cache_queue      q;
 703         int                     offset; /* if non-0, we have a refcnt on next request */
 704 };
 705
 706 static ssize_t
 707 cache_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
 708 {
 709         struct cache_reader *rp = filp->private_data;
 710         struct cache_request *rq;
 711         struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;
 712         int err;
 713
 714         if (count == 0)
 715                 return 0;
 716
 717         mutex_lock(&queue_io_mutex); /* protect against multiple concurrent
 718                               * readers on this file */
 719  again:
 720         spin_lock(&queue_lock);
 721         /* need to find next request */
 722         while (rp->q.list.next != &cd->queue &&
 723                list_entry(rp->q.list.next, struct cache_queue, list)
 724                ->reader) {
 725                 struct list_head *next = rp->q.list.next;
 726                 list_move(&rp->q.list, next);
 727         }
 728         if (rp->q.list.next == &cd->queue) {
 729                 spin_unlock(&queue_lock);
 730                 mutex_unlock(&queue_io_mutex);
 731                 BUG_ON(rp->offset);
 732                 return 0;
 733         }
 734         rq = container_of(rp->q.list.next, struct cache_request, q.list);
 735         BUG_ON(rq->q.reader);
 736         if (rp->offset == 0)
 737                 rq->readers++;
 738         spin_unlock(&queue_lock);
 739
 740         if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) {
 741                 err = -EAGAIN;
 742                 spin_lock(&queue_lock);
 743                 list_move(&rp->q.list, &rq->q.list);
 744                 spin_unlock(&queue_lock);
 745         } else {
 746                 if (rp->offset + count > rq->len)
 747                         count = rq->len - rp->offset;
 748                 err = -EFAULT;
 749                 if (copy_to_user(buf, rq->buf + rp->offset, count))
 750                         goto out;
 751                 rp->offset += count;
 752                 if (rp->offset >= rq->len) {
 753                         rp->offset = 0;
 754                         spin_lock(&queue_lock);
 755                         list_move(&rp->q.list, &rq->q.list);
 756                         spin_unlock(&queue_lock);
 757                 }
 758                 err = 0;
 759         }
 760  out:
 761         if (rp->offset == 0) {
 762                 /* need to release rq */
 763                 spin_lock(&queue_lock);
 764                 rq->readers--;
 765                 if (rq->readers == 0 &&
 766                     !test_bit(CACHE_PENDING, &rq->item->flags)) {
 767                         list_del(&rq->q.list);
 768                         spin_unlock(&queue_lock);
 769                         cache_put(rq->item, cd);
 770                         kfree(rq->buf);
 771                         kfree(rq);
 772                 } else
 773                         spin_unlock(&queue_lock);
 774         }
 775         if (err == -EAGAIN)
 776                 goto again;
 777         mutex_unlock(&queue_io_mutex);
 778         return err ? err :  count;
 779 }
 780
 781 static char write_buf[8192]; /* protected by queue_io_mutex */
 782
 783 static ssize_t
 784 cache_write(struct file *filp, const char __user *buf, size_t count,
 785             loff_t *ppos)
 786 {
 787         int err;
 788         struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;
 789
 790         if (count == 0)
 791                 return 0;
 792         if (count >= sizeof(write_buf))
 793                 return -EINVAL;
 794
 795         mutex_lock(&queue_io_mutex);
 796
 797         if (copy_from_user(write_buf, buf, count)) {
 798                 mutex_unlock(&queue_io_mutex);
 799                 return -EFAULT;
 800         }
 801         write_buf[count] = '\0';
 802         if (cd->cache_parse)
 803                 err = cd->cache_parse(cd, write_buf, count);
 804         else
 805                 err = -EINVAL;
 806
 807         mutex_unlock(&queue_io_mutex);
 808         return err ? err : count;
 809 }
 810
 811 static DECLARE_WAIT_QUEUE_HEAD(queue_wait);
 812
 813 static unsigned int
 814 cache_poll(struct file *filp, poll_table *wait)
 815 {
 816         unsigned int mask;
 817         struct cache_reader *rp = filp->private_data;
 818         struct cache_queue *cq;
 819         struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;
 820
 821         poll_wait(filp, &queue_wait, wait);
 822
 823         /* alway allow write */
 824         mask = POLL_OUT | POLLWRNORM;
 825
 826         if (!rp)
 827                 return mask;
 828
 829         spin_lock(&queue_lock);
 830
 831         for (cq= &rp->q; &cq->list != &cd->queue;
 832              cq = list_entry(cq->list.next, struct cache_queue, list))
 833                 if (!cq->reader) {
 834                         mask |= POLLIN | POLLRDNORM;
 835                         break;
 836                 }
 837         spin_unlock(&queue_lock);
 838         return mask;
 839 }
 840
 841 static int
 842 cache_ioctl(struct inode *ino, struct file *filp,
 843             unsigned int cmd, unsigned long arg)
 844 {
 845         int len = 0;
 846         struct cache_reader *rp = filp->private_data;
 847         struct cache_queue *cq;
 848         struct cache_detail *cd = PDE(ino)->data;
 849
 850         if (cmd != FIONREAD || !rp)
 851                 return -EINVAL;
 852
 853         spin_lock(&queue_lock);
 854
 855         /* only find the length remaining in current request,
 856          * or the length of the next request
 857          */
 858         for (cq= &rp->q; &cq->list != &cd->queue;
 859              cq = list_entry(cq->list.next, struct cache_queue, list))
 860                 if (!cq->reader) {
 861                         struct cache_request *cr =
 862                                 container_of(cq, struct cache_request, q);
 863                         len = cr->len - rp->offset;
 864                         break;
 865                 }
 866         spin_unlock(&queue_lock);
 867
 868         return put_user(len, (int __user *)arg);
 869 }
 870
 871 static int
 872 cache_open(struct inode *inode, struct file *filp)
 873 {
 874         struct cache_reader *rp = NULL;
 875
 876         nonseekable_open(inode, filp);
 877         if (filp->f_mode & FMODE_READ) {
 878                 struct cache_detail *cd = PDE(inode)->data;
 879
 880                 rp = kmalloc(sizeof(*rp), GFP_KERNEL);
 881                 if (!rp)
 882                         return -ENOMEM;
 883                 rp->offset = 0;
 884                 rp->q.reader = 1;
 885                 atomic_inc(&cd->readers);
 886                 spin_lock(&queue_lock);
 887                 list_add(&rp->q.list, &cd->queue);
 888                 spin_unlock(&queue_lock);
 889         }
 890         filp->private_data = rp;
 891         return 0;
 892 }
 893
 894 static int
 895 cache_release(struct inode *inode, struct file *filp)
 896 {
 897         struct cache_reader *rp = filp->private_data;
 898         struct cache_detail *cd = PDE(inode)->data;
 899
 900         if (rp) {
 901                 spin_lock(&queue_lock);
 902                 if (rp->offset) {
 903                         struct cache_queue *cq;
 904                         for (cq= &rp->q; &cq->list != &cd->queue;
 905                              cq = list_entry(cq->list.next, struct cache_queue, list))
 906                                 if (!cq->reader) {
 907                                         container_of(cq, struct cache_request, q)
 908                                                 ->readers--;
 909                                         break;
 910                                 }
 911                         rp->offset = 0;
 912                 }
 913                 list_del(&rp->q.list);
 914                 spin_unlock(&queue_lock);
 915
 916                 filp->private_data = NULL;
 917                 kfree(rp);
 918
 919                 cd->last_close = get_seconds();
 920                 atomic_dec(&cd->readers);
 921         }
 922         return 0;
 923 }
 924
 925
 926
 927 static const struct file_operations cache_file_operations = {
 928         .owner          = THIS_MODULE,
 929         .llseek         = no_llseek,
 930         .read           = cache_read,
 931         .write          = cache_write,
 932         .poll           = cache_poll,
 933         .ioctl          = cache_ioctl, /* for FIONREAD */
 934         .open           = cache_open,
 935         .release        = cache_release,
 936 };
 937
 938
 939 static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch)
 940 {
 941         struct cache_queue *cq;
 942         spin_lock(&queue_lock);
 943         list_for_each_entry(cq, &detail->queue, list)
 944                 if (!cq->reader) {
 945                         struct cache_request *cr = container_of(cq, struct cache_request, q);
 946                         if (cr->item != ch)
 947                                 continue;
 948                         if (cr->readers != 0)
 949                                 continue;
 950                         list_del(&cr->q.list);
 951                         spin_unlock(&queue_lock);
 952                         cache_put(cr->item, detail);
 953                         kfree(cr->buf);
 954                         kfree(cr);
 955                         return;
 956                 }
 957         spin_unlock(&queue_lock);
 958 }
 959
 960 /*
 961  * Support routines for text-based upcalls.
 962  * Fields are separated by spaces.
 963  * Fields are either mangled to quote space tab newline slosh with slosh
 964  * or a hexified with a leading \x
 965  * Record is terminated with newline.
 966  *
 967  */
 968
 969 void qword_add(char **bpp, int *lp, char *str)
 970 {
 971         char *bp = *bpp;
 972         int len = *lp;
 973         char c;
 974
 975         if (len < 0) return;
 976
 977         while ((c=*str++) && len)
 978                 switch(c) {
 979                 case ' ':
 980                 case '\t':
 981                 case '\n':
 982                 case '\\':
 983                         if (len >= 4) {
 984                                 *bp++ = '\\';
 985                                 *bp++ = '0' + ((c & 0300)>>6);
 986                                 *bp++ = '0' + ((c & 0070)>>3);
 987                                 *bp++ = '0' + ((c & 0007)>>0);
 988                         }
 989                         len -= 4;
 990                         break;
 991                 default:
 992                         *bp++ = c;
 993                         len--;
 994                 }
 995         if (c || len <1) len = -1;
 996         else {
 997                 *bp++ = ' ';
 998                 len--;
 999         }
1000         *bpp = bp;
1001         *lp = len;
1002 }
1003 EXPORT_SYMBOL_GPL(qword_add);
1004
1005 void qword_addhex(char **bpp, int *lp, char *buf, int blen)
1006 {
1007         char *bp = *bpp;
1008         int len = *lp;
1009
1010         if (len < 0) return;
1011
1012         if (len > 2) {
1013                 *bp++ = '\\';
1014                 *bp++ = 'x';
1015                 len -= 2;
1016                 while (blen && len >= 2) {
1017                         unsigned char c = *buf++;
1018                         *bp++ = '0' + ((c&0xf0)>>4) + (c>=0xa0)*('a'-'9'-1);
1019                         *bp++ = '0' + (c&0x0f) + ((c&0x0f)>=0x0a)*('a'-'9'-1);
1020                         len -= 2;
1021                         blen--;
1022                 }
1023         }
1024         if (blen || len<1) len = -1;
1025         else {
1026                 *bp++ = ' ';
1027                 len--;
1028         }
1029         *bpp = bp;
1030         *lp = len;
1031 }
1032 EXPORT_SYMBOL_GPL(qword_addhex);
1033
1034 static void warn_no_listener(struct cache_detail *detail)
1035 {
1036         if (detail->last_warn != detail->last_close) {
1037                 detail->last_warn = detail->last_close;
1038                 if (detail->warn_no_listener)
1039                         detail->warn_no_listener(detail);
1040         }
1041 }
1042
1043 /*
1044  * register an upcall request to user-space.
1045  * Each request is at most one page long.
1046  */
1047 static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h)
1048 {
1049
1050         char *buf;
1051         struct cache_request *crq;
1052         char *bp;
1053         int len;
1054
1055         if (detail->cache_request == NULL)
1056                 return -EINVAL;
1057
1058         if (atomic_read(&detail->readers) == 0 &&
1059             detail->last_close < get_seconds() - 30) {
1060                         warn_no_listener(detail);
1061                         return -EINVAL;
1062         }
1063
1064         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
1065         if (!buf)
1066                 return -EAGAIN;
1067
1068         crq = kmalloc(sizeof (*crq), GFP_KERNEL);
1069         if (!crq) {
1070                 kfree(buf);
1071                 return -EAGAIN;
1072         }
1073
1074         bp = buf; len = PAGE_SIZE;
1075
1076         detail->cache_request(detail, h, &bp, &len);
1077
1078         if (len < 0) {
1079                 kfree(buf);
1080                 kfree(crq);
1081                 return -EAGAIN;
1082         }
1083         crq->q.reader = 0;
1084         crq->item = cache_get(h);
1085         crq->buf = buf;
1086         crq->len = PAGE_SIZE - len;
1087         crq->readers = 0;
1088         spin_lock(&queue_lock);
1089         list_add_tail(&crq->q.list, &detail->queue);
1090         spin_unlock(&queue_lock);
1091         wake_up(&queue_wait);
1092         return 0;
1093 }
1094
1095 /*
1096  * parse a message from user-space and pass it
1097  * to an appropriate cache
1098  * Messages are, like requests, separated into fields by
1099  * spaces and dequotes as \xHEXSTRING or embedded \nnn octal
1100  *
1101  * Message is
1102  *   reply cachename expiry key ... content....
1103  *
1104  * key and content are both parsed by cache
1105  */
1106
1107 #define isodigit(c) (isdigit(c) && c <= '7')
1108 int qword_get(char **bpp, char *dest, int bufsize)
1109 {
1110         /* return bytes copied, or -1 on error */
1111         char *bp = *bpp;
1112         int len = 0;
1113
1114         while (*bp == ' ') bp++;
1115
1116         if (bp[0] == '\\' && bp[1] == 'x') {
1117                 /* HEX STRING */
1118                 bp += 2;
1119                 while (isxdigit(bp[0]) && isxdigit(bp[1]) && len < bufsize) {
1120                         int byte = isdigit(*bp) ? *bp-'0' : toupper(*bp)-'A'+10;
1121                         bp++;
1122                         byte <<= 4;
1123                         byte |= isdigit(*bp) ? *bp-'0' : toupper(*bp)-'A'+10;
1124                         *dest++ = byte;
1125                         bp++;
1126                         len++;
1127                 }
1128         } else {
1129                 /* text with \nnn octal quoting */
1130                 while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) {
1131                         if (*bp == '\\' &&
1132                             isodigit(bp[1]) && (bp[1] <= '3') &&
1133                             isodigit(bp[2]) &&
1134                             isodigit(bp[3])) {
1135                                 int byte = (*++bp -'0');
1136                                 bp++;
1137                                 byte = (byte << 3) | (*bp++ - '0');
1138                                 byte = (byte << 3) | (*bp++ - '0');
1139                                 *dest++ = byte;
1140                                 len++;
1141                         } else {
1142                                 *dest++ = *bp++;
1143                                 len++;
1144                         }
1145                 }
1146         }
1147
1148         if (*bp != ' ' && *bp != '\n' && *bp != '\0')
1149                 return -1;
1150         while (*bp == ' ') bp++;
1151         *bpp = bp;
1152         *dest = '\0';
1153         return len;
1154 }
1155 EXPORT_SYMBOL_GPL(qword_get);
1156
1157
1158 /*
1159  * support /proc/sunrpc/cache/$CACHENAME/content
1160  * as a seqfile.
1161  * We call ->cache_show passing NULL for the item to
1162  * get a header, then pass each real item in the cache
1163  */
1164
1165 struct handle {
1166         struct cache_detail *cd;
1167 };
1168
1169 static void *c_start(struct seq_file *m, loff_t *pos)
1170         __acquires(cd->hash_lock)
1171 {
1172         loff_t n = *pos;
1173         unsigned hash, entry;
1174         struct cache_head *ch;
1175         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1176
1177
1178         read_lock(&cd->hash_lock);
1179         if (!n--)
1180                 return SEQ_START_TOKEN;
1181         hash = n >> 32;
1182         entry = n & ((1LL<<32) - 1);
1183
1184         for (ch=cd->hash_table[hash]; ch; ch=ch->next)
1185                 if (!entry--)
1186                         return ch;
1187         n &= ~((1LL<<32) - 1);
1188         do {
1189                 hash++;
1190                 n += 1LL<<32;
1191         } while(hash < cd->hash_size &&
1192                 cd->hash_table[hash]==NULL);
1193         if (hash >= cd->hash_size)
1194                 return NULL;
1195         *pos = n+1;
1196         return cd->hash_table[hash];
1197 }
1198
1199 static void *c_next(struct seq_file *m, void *p, loff_t *pos)
1200 {
1201         struct cache_head *ch = p;
1202         int hash = (*pos >> 32);
1203         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1204
1205         if (p == SEQ_START_TOKEN)
1206                 hash = 0;
1207         else if (ch->next == NULL) {
1208                 hash++;
1209                 *pos += 1LL<<32;
1210         } else {
1211                 ++*pos;
1212                 return ch->next;
1213         }
1214         *pos &= ~((1LL<<32) - 1);
1215         while (hash < cd->hash_size &&
1216                cd->hash_table[hash] == NULL) {
1217                 hash++;
1218                 *pos += 1LL<<32;
1219         }
1220         if (hash >= cd->hash_size)
1221                 return NULL;
1222         ++*pos;
1223         return cd->hash_table[hash];
1224 }
1225
1226 static void c_stop(struct seq_file *m, void *p)
1227         __releases(cd->hash_lock)
1228 {
1229         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1230         read_unlock(&cd->hash_lock);
1231 }
1232
1233 static int c_show(struct seq_file *m, void *p)
1234 {
1235         struct cache_head *cp = p;
1236         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1237
1238         if (p == SEQ_START_TOKEN)
1239                 return cd->cache_show(m, cd, NULL);
1240
1241         ifdebug(CACHE)
1242                 seq_printf(m, "# expiry=%ld refcnt=%d flags=%lx\n",
1243                            cp->expiry_time, atomic_read(&cp->ref.refcount), cp->flags);
1244         cache_get(cp);
1245         if (cache_check(cd, cp, NULL))
1246                 /* cache_check does a cache_put on failure */
1247                 seq_printf(m, "# ");
1248         else
1249                 cache_put(cp, cd);
1250
1251         return cd->cache_show(m, cd, cp);
1252 }
1253
1254 static const struct seq_operations cache_content_op = {
1255         .start  = c_start,
1256         .next   = c_next,
1257         .stop   = c_stop,
1258         .show   = c_show,
1259 };
1260
1261 static int content_open(struct inode *inode, struct file *file)
1262 {
1263         struct handle *han;
1264         struct cache_detail *cd = PDE(inode)->data;
1265
1266         han = __seq_open_private(file, &cache_content_op, sizeof(*han));
1267         if (han == NULL)
1268                 return -ENOMEM;
1269
1270         han->cd = cd;
1271         return 0;
1272 }
1273
1274 static const struct file_operations content_file_operations = {
1275         .open           = content_open,
1276         .read           = seq_read,
1277         .llseek         = seq_lseek,
1278         .release        = seq_release_private,
1279 };
1280
1281 static ssize_t read_flush(struct file *file, char __user *buf,
1282                             size_t count, loff_t *ppos)
1283 {
1284         struct cache_detail *cd = PDE(file->f_path.dentry->d_inode)->data;
1285         char tbuf[20];
1286         unsigned long p = *ppos;
1287         size_t len;
1288
1289         sprintf(tbuf, "%lu\n", cd->flush_time);
1290         len = strlen(tbuf);
1291         if (p >= len)
1292                 return 0;
1293         len -= p;
1294         if (len > count)
1295                 len = count;
1296         if (copy_to_user(buf, (void*)(tbuf+p), len))
1297                 return -EFAULT;
1298         *ppos += len;
1299         return len;
1300 }
1301
1302 static ssize_t write_flush(struct file * file, const char __user * buf,
1303                              size_t count, loff_t *ppos)
1304 {
1305         struct cache_detail *cd = PDE(file->f_path.dentry->d_inode)->data;
1306         char tbuf[20];
1307         char *ep;
1308         long flushtime;
1309         if (*ppos || count > sizeof(tbuf)-1)
1310                 return -EINVAL;
1311         if (copy_from_user(tbuf, buf, count))
1312                 return -EFAULT;
1313         tbuf[count] = 0;
1314         flushtime = simple_strtoul(tbuf, &ep, 0);
1315         if (*ep && *ep != '\n')
1316                 return -EINVAL;
1317
1318         cd->flush_time = flushtime;
1319         cd->nextcheck = get_seconds();
1320         cache_flush();
1321
1322         *ppos += count;
1323         return count;
1324 }
1325
1326 static const struct file_operations cache_flush_operations = {
1327         .open           = nonseekable_open,
1328         .read           = read_flush,
1329         .write          = write_flush,
1330 };