net/sunrpc/cache.c

   1 /*
   2  * net/sunrpc/cache.c
   3  *
   4  * Generic code for various authentication-related caches
   5  * used by sunrpc clients and servers.
   6  *
   7  * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
   8  *
   9  * Released under terms in GPL version 2.  See COPYING.
  10  *
  11  */
  12
  13 #include <linux/types.h>
  14 #include <linux/fs.h>
  15 #include <linux/file.h>
  16 #include <linux/slab.h>
  17 #include <linux/signal.h>
  18 #include <linux/sched.h>
  19 #include <linux/kmod.h>
  20 #include <linux/list.h>
  21 #include <linux/module.h>
  22 #include <linux/ctype.h>
  23 #include <asm/uaccess.h>
  24 #include <linux/poll.h>
  25 #include <linux/seq_file.h>
  26 #include <linux/proc_fs.h>
  27 #include <linux/net.h>
  28 #include <linux/workqueue.h>
  29 #include <linux/mutex.h>
  30 #include <asm/ioctls.h>
  31 #include <linux/sunrpc/types.h>
  32 #include <linux/sunrpc/cache.h>
  33 #include <linux/sunrpc/stats.h>
  34
  35 #define  RPCDBG_FACILITY RPCDBG_CACHE
  36
  37 static int cache_defer_req(struct cache_req *req, struct cache_head *item);
  38 static void cache_revisit_request(struct cache_head *item);
  39
  40 static void cache_init(struct cache_head *h)
  41 {
  42         time_t now = get_seconds();
  43         h->next = NULL;
  44         h->flags = 0;
  45         kref_init(&h->ref);
  46         h->expiry_time = now + CACHE_NEW_EXPIRY;
  47         h->last_refresh = now;
  48 }
  49
  50 struct cache_head *sunrpc_cache_lookup(struct cache_detail *detail,
  51                                        struct cache_head *key, int hash)
  52 {
  53         struct cache_head **head,  **hp;
  54         struct cache_head *new = NULL;
  55
  56         head = &detail->hash_table[hash];
  57
  58         read_lock(&detail->hash_lock);
  59
  60         for (hp=head; *hp != NULL ; hp = &(*hp)->next) {
  61                 struct cache_head *tmp = *hp;
  62                 if (detail->match(tmp, key)) {
  63                         cache_get(tmp);
  64                         read_unlock(&detail->hash_lock);
  65                         return tmp;
  66                 }
  67         }
  68         read_unlock(&detail->hash_lock);
  69         /* Didn't find anything, insert an empty entry */
  70
  71         new = detail->alloc();
  72         if (!new)
  73                 return NULL;
  74         /* must fully initialise 'new', else
  75          * we might get lose if we need to
  76          * cache_put it soon.
  77          */
  78         cache_init(new);
  79         detail->init(new, key);
  80
  81         write_lock(&detail->hash_lock);
  82
  83         /* check if entry appeared while we slept */
  84         for (hp=head; *hp != NULL ; hp = &(*hp)->next) {
  85                 struct cache_head *tmp = *hp;
  86                 if (detail->match(tmp, key)) {
  87                         cache_get(tmp);
  88                         write_unlock(&detail->hash_lock);
  89                         cache_put(new, detail);
  90                         return tmp;
  91                 }
  92         }
  93         new->next = *head;
  94         *head = new;
  95         detail->entries++;
  96         cache_get(new);
  97         write_unlock(&detail->hash_lock);
  98
  99         return new;
 100 }
 101 EXPORT_SYMBOL(sunrpc_cache_lookup);
 102
 103
 104 static void queue_loose(struct cache_detail *detail, struct cache_head *ch);
 105
 106 static int cache_fresh_locked(struct cache_head *head, time_t expiry)
 107 {
 108         head->expiry_time = expiry;
 109         head->last_refresh = get_seconds();
 110         return !test_and_set_bit(CACHE_VALID, &head->flags);
 111 }
 112
 113 static void cache_fresh_unlocked(struct cache_head *head,
 114                         struct cache_detail *detail, int new)
 115 {
 116         if (new)
 117                 cache_revisit_request(head);
 118         if (test_and_clear_bit(CACHE_PENDING, &head->flags)) {
 119                 cache_revisit_request(head);
 120                 queue_loose(detail, head);
 121         }
 122 }
 123
 124 struct cache_head *sunrpc_cache_update(struct cache_detail *detail,
 125                                        struct cache_head *new, struct cache_head *old, int hash)
 126 {
 127         /* The 'old' entry is to be replaced by 'new'.
 128          * If 'old' is not VALID, we update it directly,
 129          * otherwise we need to replace it
 130          */
 131         struct cache_head **head;
 132         struct cache_head *tmp;
 133         int is_new;
 134
 135         if (!test_bit(CACHE_VALID, &old->flags)) {
 136                 write_lock(&detail->hash_lock);
 137                 if (!test_bit(CACHE_VALID, &old->flags)) {
 138                         if (test_bit(CACHE_NEGATIVE, &new->flags))
 139                                 set_bit(CACHE_NEGATIVE, &old->flags);
 140                         else
 141                                 detail->update(old, new);
 142                         is_new = cache_fresh_locked(old, new->expiry_time);
 143                         write_unlock(&detail->hash_lock);
 144                         cache_fresh_unlocked(old, detail, is_new);
 145                         return old;
 146                 }
 147                 write_unlock(&detail->hash_lock);
 148         }
 149         /* We need to insert a new entry */
 150         tmp = detail->alloc();
 151         if (!tmp) {
 152                 cache_put(old, detail);
 153                 return NULL;
 154         }
 155         cache_init(tmp);
 156         detail->init(tmp, old);
 157         head = &detail->hash_table[hash];
 158
 159         write_lock(&detail->hash_lock);
 160         if (test_bit(CACHE_NEGATIVE, &new->flags))
 161                 set_bit(CACHE_NEGATIVE, &tmp->flags);
 162         else
 163                 detail->update(tmp, new);
 164         tmp->next = *head;
 165         *head = tmp;
 166         detail->entries++;
 167         cache_get(tmp);
 168         is_new = cache_fresh_locked(tmp, new->expiry_time);
 169         cache_fresh_locked(old, 0);
 170         write_unlock(&detail->hash_lock);
 171         cache_fresh_unlocked(tmp, detail, is_new);
 172         cache_fresh_unlocked(old, detail, 0);
 173         cache_put(old, detail);
 174         return tmp;
 175 }
 176 EXPORT_SYMBOL(sunrpc_cache_update);
 177
 178 static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h);
 179 /*
 180  * This is the generic cache management routine for all
 181  * the authentication caches.
 182  * It checks the currency of a cache item and will (later)
 183  * initiate an upcall to fill it if needed.
 184  *
 185  *
 186  * Returns 0 if the cache_head can be used, or cache_puts it and returns
 187  * -EAGAIN if upcall is pending,
 188  * -ETIMEDOUT if upcall failed and should be retried,
 189  * -ENOENT if cache entry was negative
 190  */
 191 int cache_check(struct cache_detail *detail,
 192                     struct cache_head *h, struct cache_req *rqstp)
 193 {
 194         int rv;
 195         long refresh_age, age;
 196
 197         /* First decide return status as best we can */
 198         if (!test_bit(CACHE_VALID, &h->flags) ||
 199             h->expiry_time < get_seconds())
 200                 rv = -EAGAIN;
 201         else if (detail->flush_time > h->last_refresh)
 202                 rv = -EAGAIN;
 203         else {
 204                 /* entry is valid */
 205                 if (test_bit(CACHE_NEGATIVE, &h->flags))
 206                         rv = -ENOENT;
 207                 else rv = 0;
 208         }
 209
 210         /* now see if we want to start an upcall */
 211         refresh_age = (h->expiry_time - h->last_refresh);
 212         age = get_seconds() - h->last_refresh;
 213
 214         if (rqstp == NULL) {
 215                 if (rv == -EAGAIN)
 216                         rv = -ENOENT;
 217         } else if (rv == -EAGAIN || age > refresh_age/2) {
 218                 dprintk("RPC:       Want update, refage=%ld, age=%ld\n",
 219                                 refresh_age, age);
 220                 if (!test_and_set_bit(CACHE_PENDING, &h->flags)) {
 221                         switch (cache_make_upcall(detail, h)) {
 222                         case -EINVAL:
 223                                 clear_bit(CACHE_PENDING, &h->flags);
 224                                 if (rv == -EAGAIN) {
 225                                         set_bit(CACHE_NEGATIVE, &h->flags);
 226                                         cache_fresh_unlocked(h, detail,
 227                                              cache_fresh_locked(h, get_seconds()+CACHE_NEW_EXPIRY));
 228                                         rv = -ENOENT;
 229                                 }
 230                                 break;
 231
 232                         case -EAGAIN:
 233                                 clear_bit(CACHE_PENDING, &h->flags);
 234                                 cache_revisit_request(h);
 235                                 break;
 236                         }
 237                 }
 238         }
 239
 240         if (rv == -EAGAIN)
 241                 if (cache_defer_req(rqstp, h) != 0)
 242                         rv = -ETIMEDOUT;
 243
 244         if (rv)
 245                 cache_put(h, detail);
 246         return rv;
 247 }
 248 EXPORT_SYMBOL(cache_check);
 249
 250 /*
 251  * caches need to be periodically cleaned.
 252  * For this we maintain a list of cache_detail and
 253  * a current pointer into that list and into the table
 254  * for that entry.
 255  *
 256  * Each time clean_cache is called it finds the next non-empty entry
 257  * in the current table and walks the list in that entry
 258  * looking for entries that can be removed.
 259  *
 260  * An entry gets removed if:
 261  * - The expiry is before current time
 262  * - The last_refresh time is before the flush_time for that cache
 263  *
 264  * later we might drop old entries with non-NEVER expiry if that table
 265  * is getting 'full' for some definition of 'full'
 266  *
 267  * The question of "how often to scan a table" is an interesting one
 268  * and is answered in part by the use of the "nextcheck" field in the
 269  * cache_detail.
 270  * When a scan of a table begins, the nextcheck field is set to a time
 271  * that is well into the future.
 272  * While scanning, if an expiry time is found that is earlier than the
 273  * current nextcheck time, nextcheck is set to that expiry time.
 274  * If the flush_time is ever set to a time earlier than the nextcheck
 275  * time, the nextcheck time is then set to that flush_time.
 276  *
 277  * A table is then only scanned if the current time is at least
 278  * the nextcheck time.
 279  *
 280  */
 281
 282 static LIST_HEAD(cache_list);
 283 static DEFINE_SPINLOCK(cache_list_lock);
 284 static struct cache_detail *current_detail;
 285 static int current_index;
 286
 287 static const struct file_operations cache_file_operations;
 288 static const struct file_operations content_file_operations;
 289 static const struct file_operations cache_flush_operations;
 290
 291 static void do_cache_clean(struct work_struct *work);
 292 static DECLARE_DELAYED_WORK(cache_cleaner, do_cache_clean);
 293
 294 static void remove_cache_proc_entries(struct cache_detail *cd)
 295 {
 296         if (cd->proc_ent == NULL)
 297                 return;
 298         if (cd->flush_ent)
 299                 remove_proc_entry("flush", cd->proc_ent);
 300         if (cd->channel_ent)
 301                 remove_proc_entry("channel", cd->proc_ent);
 302         if (cd->content_ent)
 303                 remove_proc_entry("content", cd->proc_ent);
 304         cd->proc_ent = NULL;
 305         remove_proc_entry(cd->name, proc_net_rpc);
 306 }
 307
 308 #ifdef CONFIG_PROC_FS
 309 static int create_cache_proc_entries(struct cache_detail *cd)
 310 {
 311         struct proc_dir_entry *p;
 312
 313         cd->proc_ent = proc_mkdir(cd->name, proc_net_rpc);
 314         if (cd->proc_ent == NULL)
 315                 goto out_nomem;
 316         cd->proc_ent->owner = cd->owner;
 317         cd->channel_ent = cd->content_ent = NULL;
 318
 319         p = create_proc_entry("flush", S_IFREG|S_IRUSR|S_IWUSR, cd->proc_ent);
 320         cd->flush_ent = p;
 321         if (p == NULL)
 322                 goto out_nomem;
 323         p->proc_fops = &cache_flush_operations;
 324         p->owner = cd->owner;
 325         p->data = cd;
 326
 327         if (cd->cache_request || cd->cache_parse) {
 328                 p = create_proc_entry("channel", S_IFREG|S_IRUSR|S_IWUSR,
 329                                       cd->proc_ent);
 330                 cd->channel_ent = p;
 331                 if (p == NULL)
 332                         goto out_nomem;
 333                 p->proc_fops = &cache_file_operations;
 334                 p->owner = cd->owner;
 335                 p->data = cd;
 336         }
 337         if (cd->cache_show) {
 338                 p = create_proc_entry("content", S_IFREG|S_IRUSR|S_IWUSR,
 339                                       cd->proc_ent);
 340                 cd->content_ent = p;
 341                 if (p == NULL)
 342                         goto out_nomem;
 343                 p->proc_fops = &content_file_operations;
 344                 p->owner = cd->owner;
 345                 p->data = cd;
 346         }
 347         return 0;
 348 out_nomem:
 349         remove_cache_proc_entries(cd);
 350         return -ENOMEM;
 351 }
 352 #else /* CONFIG_PROC_FS */
 353 static int create_cache_proc_entries(struct cache_detail *cd)
 354 {
 355         return 0;
 356 }
 357 #endif
 358
 359 int cache_register(struct cache_detail *cd)
 360 {
 361         int ret;
 362
 363         ret = create_cache_proc_entries(cd);
 364         if (ret)
 365                 return ret;
 366         rwlock_init(&cd->hash_lock);
 367         INIT_LIST_HEAD(&cd->queue);
 368         spin_lock(&cache_list_lock);
 369         cd->nextcheck = 0;
 370         cd->entries = 0;
 371         atomic_set(&cd->readers, 0);
 372         cd->last_close = 0;
 373         cd->last_warn = -1;
 374         list_add(&cd->others, &cache_list);
 375         spin_unlock(&cache_list_lock);
 376
 377         /* start the cleaning process */
 378         schedule_delayed_work(&cache_cleaner, 0);
 379         return 0;
 380 }
 381 EXPORT_SYMBOL(cache_register);
 382
 383 void cache_unregister(struct cache_detail *cd)
 384 {
 385         cache_purge(cd);
 386         spin_lock(&cache_list_lock);
 387         write_lock(&cd->hash_lock);
 388         if (cd->entries || atomic_read(&cd->inuse)) {
 389                 write_unlock(&cd->hash_lock);
 390                 spin_unlock(&cache_list_lock);
 391                 goto out;
 392         }
 393         if (current_detail == cd)
 394                 current_detail = NULL;
 395         list_del_init(&cd->others);
 396         write_unlock(&cd->hash_lock);
 397         spin_unlock(&cache_list_lock);
 398         remove_cache_proc_entries(cd);
 399         if (list_empty(&cache_list)) {
 400                 /* module must be being unloaded so its safe to kill the worker */
 401                 cancel_delayed_work_sync(&cache_cleaner);
 402         }
 403         return;
 404 out:
 405         printk(KERN_ERR "nfsd: failed to unregister %s cache\n", cd->name);
 406 }
 407 EXPORT_SYMBOL(cache_unregister);
 408
 409 /* clean cache tries to find something to clean
 410  * and cleans it.
 411  * It returns 1 if it cleaned something,
 412  *            0 if it didn't find anything this time
 413  *           -1 if it fell off the end of the list.
 414  */
 415 static int cache_clean(void)
 416 {
 417         int rv = 0;
 418         struct list_head *next;
 419
 420         spin_lock(&cache_list_lock);
 421
 422         /* find a suitable table if we don't already have one */
 423         while (current_detail == NULL ||
 424             current_index >= current_detail->hash_size) {
 425                 if (current_detail)
 426                         next = current_detail->others.next;
 427                 else
 428                         next = cache_list.next;
 429                 if (next == &cache_list) {
 430                         current_detail = NULL;
 431                         spin_unlock(&cache_list_lock);
 432                         return -1;
 433                 }
 434                 current_detail = list_entry(next, struct cache_detail, others);
 435                 if (current_detail->nextcheck > get_seconds())
 436                         current_index = current_detail->hash_size;
 437                 else {
 438                         current_index = 0;
 439                         current_detail->nextcheck = get_seconds()+30*60;
 440                 }
 441         }
 442
 443         /* find a non-empty bucket in the table */
 444         while (current_detail &&
 445                current_index < current_detail->hash_size &&
 446                current_detail->hash_table[current_index] == NULL)
 447                 current_index++;
 448
 449         /* find a cleanable entry in the bucket and clean it, or set to next bucket */
 450
 451         if (current_detail && current_index < current_detail->hash_size) {
 452                 struct cache_head *ch, **cp;
 453                 struct cache_detail *d;
 454
 455                 write_lock(&current_detail->hash_lock);
 456
 457                 /* Ok, now to clean this strand */
 458
 459                 cp = & current_detail->hash_table[current_index];
 460                 ch = *cp;
 461                 for (; ch; cp= & ch->next, ch= *cp) {
 462                         if (current_detail->nextcheck > ch->expiry_time)
 463                                 current_detail->nextcheck = ch->expiry_time+1;
 464                         if (ch->expiry_time >= get_seconds()
 465                             && ch->last_refresh >= current_detail->flush_time
 466                                 )
 467                                 continue;
 468                         if (test_and_clear_bit(CACHE_PENDING, &ch->flags))
 469                                 queue_loose(current_detail, ch);
 470
 471                         if (atomic_read(&ch->ref.refcount) == 1)
 472                                 break;
 473                 }
 474                 if (ch) {
 475                         *cp = ch->next;
 476                         ch->next = NULL;
 477                         current_detail->entries--;
 478                         rv = 1;
 479                 }
 480                 write_unlock(&current_detail->hash_lock);
 481                 d = current_detail;
 482                 if (!ch)
 483                         current_index ++;
 484                 spin_unlock(&cache_list_lock);
 485                 if (ch)
 486                         cache_put(ch, d);
 487         } else
 488                 spin_unlock(&cache_list_lock);
 489
 490         return rv;
 491 }
 492
 493 /*
 494  * We want to regularly clean the cache, so we need to schedule some work ...
 495  */
 496 static void do_cache_clean(struct work_struct *work)
 497 {
 498         int delay = 5;
 499         if (cache_clean() == -1)
 500                 delay = 30*HZ;
 501
 502         if (list_empty(&cache_list))
 503                 delay = 0;
 504
 505         if (delay)
 506                 schedule_delayed_work(&cache_cleaner, delay);
 507 }
 508
 509
 510 /*
 511  * Clean all caches promptly.  This just calls cache_clean
 512  * repeatedly until we are sure that every cache has had a chance to
 513  * be fully cleaned
 514  */
 515 void cache_flush(void)
 516 {
 517         while (cache_clean() != -1)
 518                 cond_resched();
 519         while (cache_clean() != -1)
 520                 cond_resched();
 521 }
 522 EXPORT_SYMBOL(cache_flush);
 523
 524 void cache_purge(struct cache_detail *detail)
 525 {
 526         detail->flush_time = LONG_MAX;
 527         detail->nextcheck = get_seconds();
 528         cache_flush();
 529         detail->flush_time = 1;
 530 }
 531 EXPORT_SYMBOL(cache_purge);
 532
 533
 534 /*
 535  * Deferral and Revisiting of Requests.
 536  *
 537  * If a cache lookup finds a pending entry, we
 538  * need to defer the request and revisit it later.
 539  * All deferred requests are stored in a hash table,
 540  * indexed by "struct cache_head *".
 541  * As it may be wasteful to store a whole request
 542  * structure, we allow the request to provide a
 543  * deferred form, which must contain a
 544  * 'struct cache_deferred_req'
 545  * This cache_deferred_req contains a method to allow
 546  * it to be revisited when cache info is available
 547  */
 548
 549 #define DFR_HASHSIZE    (PAGE_SIZE/sizeof(struct list_head))
 550 #define DFR_HASH(item)  ((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE)
 551
 552 #define DFR_MAX 300     /* ??? */
 553
 554 static DEFINE_SPINLOCK(cache_defer_lock);
 555 static LIST_HEAD(cache_defer_list);
 556 static struct list_head cache_defer_hash[DFR_HASHSIZE];
 557 static int cache_defer_cnt;
 558
 559 static int cache_defer_req(struct cache_req *req, struct cache_head *item)
 560 {
 561         struct cache_deferred_req *dreq;
 562         int hash = DFR_HASH(item);
 563
 564         if (cache_defer_cnt >= DFR_MAX) {
 565                 /* too much in the cache, randomly drop this one,
 566                  * or continue and drop the oldest below
 567                  */
 568                 if (net_random()&1)
 569                         return -ETIMEDOUT;
 570         }
 571         dreq = req->defer(req);
 572         if (dreq == NULL)
 573                 return -ETIMEDOUT;
 574
 575         dreq->item = item;
 576         dreq->recv_time = get_seconds();
 577
 578         spin_lock(&cache_defer_lock);
 579
 580         list_add(&dreq->recent, &cache_defer_list);
 581
 582         if (cache_defer_hash[hash].next == NULL)
 583                 INIT_LIST_HEAD(&cache_defer_hash[hash]);
 584         list_add(&dreq->hash, &cache_defer_hash[hash]);
 585
 586         /* it is in, now maybe clean up */
 587         dreq = NULL;
 588         if (++cache_defer_cnt > DFR_MAX) {
 589                 dreq = list_entry(cache_defer_list.prev,
 590                                   struct cache_deferred_req, recent);
 591                 list_del(&dreq->recent);
 592                 list_del(&dreq->hash);
 593                 cache_defer_cnt--;
 594         }
 595         spin_unlock(&cache_defer_lock);
 596
 597         if (dreq) {
 598                 /* there was one too many */
 599                 dreq->revisit(dreq, 1);
 600         }
 601         if (!test_bit(CACHE_PENDING, &item->flags)) {
 602                 /* must have just been validated... */
 603                 cache_revisit_request(item);
 604         }
 605         return 0;
 606 }
 607
 608 static void cache_revisit_request(struct cache_head *item)
 609 {
 610         struct cache_deferred_req *dreq;
 611         struct list_head pending;
 612
 613         struct list_head *lp;
 614         int hash = DFR_HASH(item);
 615
 616         INIT_LIST_HEAD(&pending);
 617         spin_lock(&cache_defer_lock);
 618
 619         lp = cache_defer_hash[hash].next;
 620         if (lp) {
 621                 while (lp != &cache_defer_hash[hash]) {
 622                         dreq = list_entry(lp, struct cache_deferred_req, hash);
 623                         lp = lp->next;
 624                         if (dreq->item == item) {
 625                                 list_del(&dreq->hash);
 626                                 list_move(&dreq->recent, &pending);
 627                                 cache_defer_cnt--;
 628                         }
 629                 }
 630         }
 631         spin_unlock(&cache_defer_lock);
 632
 633         while (!list_empty(&pending)) {
 634                 dreq = list_entry(pending.next, struct cache_deferred_req, recent);
 635                 list_del_init(&dreq->recent);
 636                 dreq->revisit(dreq, 0);
 637         }
 638 }
 639
 640 void cache_clean_deferred(void *owner)
 641 {
 642         struct cache_deferred_req *dreq, *tmp;
 643         struct list_head pending;
 644
 645
 646         INIT_LIST_HEAD(&pending);
 647         spin_lock(&cache_defer_lock);
 648
 649         list_for_each_entry_safe(dreq, tmp, &cache_defer_list, recent) {
 650                 if (dreq->owner == owner) {
 651                         list_del(&dreq->hash);
 652                         list_move(&dreq->recent, &pending);
 653                         cache_defer_cnt--;
 654                 }
 655         }
 656         spin_unlock(&cache_defer_lock);
 657
 658         while (!list_empty(&pending)) {
 659                 dreq = list_entry(pending.next, struct cache_deferred_req, recent);
 660                 list_del_init(&dreq->recent);
 661                 dreq->revisit(dreq, 1);
 662         }
 663 }
 664
 665 /*
 666  * communicate with user-space
 667  *
 668  * We have a magic /proc file - /proc/sunrpc/<cachename>/channel.
 669  * On read, you get a full request, or block.
 670  * On write, an update request is processed.
 671  * Poll works if anything to read, and always allows write.
 672  *
 673  * Implemented by linked list of requests.  Each open file has
 674  * a ->private that also exists in this list.  New requests are added
 675  * to the end and may wakeup and preceding readers.
 676  * New readers are added to the head.  If, on read, an item is found with
 677  * CACHE_UPCALLING clear, we free it from the list.
 678  *
 679  */
 680
 681 static DEFINE_SPINLOCK(queue_lock);
 682 static DEFINE_MUTEX(queue_io_mutex);
 683
 684 struct cache_queue {
 685         struct list_head        list;
 686         int                     reader; /* if 0, then request */
 687 };
 688 struct cache_request {
 689         struct cache_queue      q;
 690         struct cache_head       *item;
 691         char                    * buf;
 692         int                     len;
 693         int                     readers;
 694 };
 695 struct cache_reader {
 696         struct cache_queue      q;
 697         int                     offset; /* if non-0, we have a refcnt on next request */
 698 };
 699
 700 static ssize_t
 701 cache_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
 702 {
 703         struct cache_reader *rp = filp->private_data;
 704         struct cache_request *rq;
 705         struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;
 706         int err;
 707
 708         if (count == 0)
 709                 return 0;
 710
 711         mutex_lock(&queue_io_mutex); /* protect against multiple concurrent
 712                               * readers on this file */
 713  again:
 714         spin_lock(&queue_lock);
 715         /* need to find next request */
 716         while (rp->q.list.next != &cd->queue &&
 717                list_entry(rp->q.list.next, struct cache_queue, list)
 718                ->reader) {
 719                 struct list_head *next = rp->q.list.next;
 720                 list_move(&rp->q.list, next);
 721         }
 722         if (rp->q.list.next == &cd->queue) {
 723                 spin_unlock(&queue_lock);
 724                 mutex_unlock(&queue_io_mutex);
 725                 BUG_ON(rp->offset);
 726                 return 0;
 727         }
 728         rq = container_of(rp->q.list.next, struct cache_request, q.list);
 729         BUG_ON(rq->q.reader);
 730         if (rp->offset == 0)
 731                 rq->readers++;
 732         spin_unlock(&queue_lock);
 733
 734         if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) {
 735                 err = -EAGAIN;
 736                 spin_lock(&queue_lock);
 737                 list_move(&rp->q.list, &rq->q.list);
 738                 spin_unlock(&queue_lock);
 739         } else {
 740                 if (rp->offset + count > rq->len)
 741                         count = rq->len - rp->offset;
 742                 err = -EFAULT;
 743                 if (copy_to_user(buf, rq->buf + rp->offset, count))
 744                         goto out;
 745                 rp->offset += count;
 746                 if (rp->offset >= rq->len) {
 747                         rp->offset = 0;
 748                         spin_lock(&queue_lock);
 749                         list_move(&rp->q.list, &rq->q.list);
 750                         spin_unlock(&queue_lock);
 751                 }
 752                 err = 0;
 753         }
 754  out:
 755         if (rp->offset == 0) {
 756                 /* need to release rq */
 757                 spin_lock(&queue_lock);
 758                 rq->readers--;
 759                 if (rq->readers == 0 &&
 760                     !test_bit(CACHE_PENDING, &rq->item->flags)) {
 761                         list_del(&rq->q.list);
 762                         spin_unlock(&queue_lock);
 763                         cache_put(rq->item, cd);
 764                         kfree(rq->buf);
 765                         kfree(rq);
 766                 } else
 767                         spin_unlock(&queue_lock);
 768         }
 769         if (err == -EAGAIN)
 770                 goto again;
 771         mutex_unlock(&queue_io_mutex);
 772         return err ? err :  count;
 773 }
 774
 775 static char write_buf[8192]; /* protected by queue_io_mutex */
 776
 777 static ssize_t
 778 cache_write(struct file *filp, const char __user *buf, size_t count,
 779             loff_t *ppos)
 780 {
 781         int err;
 782         struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;
 783
 784         if (count == 0)
 785                 return 0;
 786         if (count >= sizeof(write_buf))
 787                 return -EINVAL;
 788
 789         mutex_lock(&queue_io_mutex);
 790
 791         if (copy_from_user(write_buf, buf, count)) {
 792                 mutex_unlock(&queue_io_mutex);
 793                 return -EFAULT;
 794         }
 795         write_buf[count] = '\0';
 796         if (cd->cache_parse)
 797                 err = cd->cache_parse(cd, write_buf, count);
 798         else
 799                 err = -EINVAL;
 800
 801         mutex_unlock(&queue_io_mutex);
 802         return err ? err : count;
 803 }
 804
 805 static DECLARE_WAIT_QUEUE_HEAD(queue_wait);
 806
 807 static unsigned int
 808 cache_poll(struct file *filp, poll_table *wait)
 809 {
 810         unsigned int mask;
 811         struct cache_reader *rp = filp->private_data;
 812         struct cache_queue *cq;
 813         struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;
 814
 815         poll_wait(filp, &queue_wait, wait);
 816
 817         /* alway allow write */
 818         mask = POLL_OUT | POLLWRNORM;
 819
 820         if (!rp)
 821                 return mask;
 822
 823         spin_lock(&queue_lock);
 824
 825         for (cq= &rp->q; &cq->list != &cd->queue;
 826              cq = list_entry(cq->list.next, struct cache_queue, list))
 827                 if (!cq->reader) {
 828                         mask |= POLLIN | POLLRDNORM;
 829                         break;
 830                 }
 831         spin_unlock(&queue_lock);
 832         return mask;
 833 }
 834
 835 static int
 836 cache_ioctl(struct inode *ino, struct file *filp,
 837             unsigned int cmd, unsigned long arg)
 838 {
 839         int len = 0;
 840         struct cache_reader *rp = filp->private_data;
 841         struct cache_queue *cq;
 842         struct cache_detail *cd = PDE(ino)->data;
 843
 844         if (cmd != FIONREAD || !rp)
 845                 return -EINVAL;
 846
 847         spin_lock(&queue_lock);
 848
 849         /* only find the length remaining in current request,
 850          * or the length of the next request
 851          */
 852         for (cq= &rp->q; &cq->list != &cd->queue;
 853              cq = list_entry(cq->list.next, struct cache_queue, list))
 854                 if (!cq->reader) {
 855                         struct cache_request *cr =
 856                                 container_of(cq, struct cache_request, q);
 857                         len = cr->len - rp->offset;
 858                         break;
 859                 }
 860         spin_unlock(&queue_lock);
 861
 862         return put_user(len, (int __user *)arg);
 863 }
 864
 865 static int
 866 cache_open(struct inode *inode, struct file *filp)
 867 {
 868         struct cache_reader *rp = NULL;
 869
 870         nonseekable_open(inode, filp);
 871         if (filp->f_mode & FMODE_READ) {
 872                 struct cache_detail *cd = PDE(inode)->data;
 873
 874                 rp = kmalloc(sizeof(*rp), GFP_KERNEL);
 875                 if (!rp)
 876                         return -ENOMEM;
 877                 rp->offset = 0;
 878                 rp->q.reader = 1;
 879                 atomic_inc(&cd->readers);
 880                 spin_lock(&queue_lock);
 881                 list_add(&rp->q.list, &cd->queue);
 882                 spin_unlock(&queue_lock);
 883         }
 884         filp->private_data = rp;
 885         return 0;
 886 }
 887
 888 static int
 889 cache_release(struct inode *inode, struct file *filp)
 890 {
 891         struct cache_reader *rp = filp->private_data;
 892         struct cache_detail *cd = PDE(inode)->data;
 893
 894         if (rp) {
 895                 spin_lock(&queue_lock);
 896                 if (rp->offset) {
 897                         struct cache_queue *cq;
 898                         for (cq= &rp->q; &cq->list != &cd->queue;
 899                              cq = list_entry(cq->list.next, struct cache_queue, list))
 900                                 if (!cq->reader) {
 901                                         container_of(cq, struct cache_request, q)
 902                                                 ->readers--;
 903                                         break;
 904                                 }
 905                         rp->offset = 0;
 906                 }
 907                 list_del(&rp->q.list);
 908                 spin_unlock(&queue_lock);
 909
 910                 filp->private_data = NULL;
 911                 kfree(rp);
 912
 913                 cd->last_close = get_seconds();
 914                 atomic_dec(&cd->readers);
 915         }
 916         return 0;
 917 }
 918
 919
 920
 921 static const struct file_operations cache_file_operations = {
 922         .owner          = THIS_MODULE,
 923         .llseek         = no_llseek,
 924         .read           = cache_read,
 925         .write          = cache_write,
 926         .poll           = cache_poll,
 927         .ioctl          = cache_ioctl, /* for FIONREAD */
 928         .open           = cache_open,
 929         .release        = cache_release,
 930 };
 931
 932
 933 static void queue_loose(struct cache_detail *detail, struct cache_head *ch)
 934 {
 935         struct cache_queue *cq;
 936         spin_lock(&queue_lock);
 937         list_for_each_entry(cq, &detail->queue, list)
 938                 if (!cq->reader) {
 939                         struct cache_request *cr = container_of(cq, struct cache_request, q);
 940                         if (cr->item != ch)
 941                                 continue;
 942                         if (cr->readers != 0)
 943                                 continue;
 944                         list_del(&cr->q.list);
 945                         spin_unlock(&queue_lock);
 946                         cache_put(cr->item, detail);
 947                         kfree(cr->buf);
 948                         kfree(cr);
 949                         return;
 950                 }
 951         spin_unlock(&queue_lock);
 952 }
 953
 954 /*
 955  * Support routines for text-based upcalls.
 956  * Fields are separated by spaces.
 957  * Fields are either mangled to quote space tab newline slosh with slosh
 958  * or a hexified with a leading \x
 959  * Record is terminated with newline.
 960  *
 961  */
 962
 963 void qword_add(char **bpp, int *lp, char *str)
 964 {
 965         char *bp = *bpp;
 966         int len = *lp;
 967         char c;
 968
 969         if (len < 0) return;
 970
 971         while ((c=*str++) && len)
 972                 switch(c) {
 973                 case ' ':
 974                 case '\t':
 975                 case '\n':
 976                 case '\\':
 977                         if (len >= 4) {
 978                                 *bp++ = '\\';
 979                                 *bp++ = '0' + ((c & 0300)>>6);
 980                                 *bp++ = '0' + ((c & 0070)>>3);
 981                                 *bp++ = '0' + ((c & 0007)>>0);
 982                         }
 983                         len -= 4;
 984                         break;
 985                 default:
 986                         *bp++ = c;
 987                         len--;
 988                 }
 989         if (c || len <1) len = -1;
 990         else {
 991                 *bp++ = ' ';
 992                 len--;
 993         }
 994         *bpp = bp;
 995         *lp = len;
 996 }
 997 EXPORT_SYMBOL(qword_add);
 998
 999 void qword_addhex(char **bpp, int *lp, char *buf, int blen)
1000 {
1001         char *bp = *bpp;
1002         int len = *lp;
1003
1004         if (len < 0) return;
1005
1006         if (len > 2) {
1007                 *bp++ = '\\';
1008                 *bp++ = 'x';
1009                 len -= 2;
1010                 while (blen && len >= 2) {
1011                         unsigned char c = *buf++;
1012                         *bp++ = '0' + ((c&0xf0)>>4) + (c>=0xa0)*('a'-'9'-1);
1013                         *bp++ = '0' + (c&0x0f) + ((c&0x0f)>=0x0a)*('a'-'9'-1);
1014                         len -= 2;
1015                         blen--;
1016                 }
1017         }
1018         if (blen || len<1) len = -1;
1019         else {
1020                 *bp++ = ' ';
1021                 len--;
1022         }
1023         *bpp = bp;
1024         *lp = len;
1025 }
1026 EXPORT_SYMBOL(qword_addhex);
1027
1028 static void warn_no_listener(struct cache_detail *detail)
1029 {
1030         if (detail->last_warn != detail->last_close) {
1031                 detail->last_warn = detail->last_close;
1032                 if (detail->warn_no_listener)
1033                         detail->warn_no_listener(detail);
1034         }
1035 }
1036
1037 /*
1038  * register an upcall request to user-space.
1039  * Each request is at most one page long.
1040  */
1041 static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h)
1042 {
1043
1044         char *buf;
1045         struct cache_request *crq;
1046         char *bp;
1047         int len;
1048
1049         if (detail->cache_request == NULL)
1050                 return -EINVAL;
1051
1052         if (atomic_read(&detail->readers) == 0 &&
1053             detail->last_close < get_seconds() - 30) {
1054                         warn_no_listener(detail);
1055                         return -EINVAL;
1056         }
1057
1058         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
1059         if (!buf)
1060                 return -EAGAIN;
1061
1062         crq = kmalloc(sizeof (*crq), GFP_KERNEL);
1063         if (!crq) {
1064                 kfree(buf);
1065                 return -EAGAIN;
1066         }
1067
1068         bp = buf; len = PAGE_SIZE;
1069
1070         detail->cache_request(detail, h, &bp, &len);
1071
1072         if (len < 0) {
1073                 kfree(buf);
1074                 kfree(crq);
1075                 return -EAGAIN;
1076         }
1077         crq->q.reader = 0;
1078         crq->item = cache_get(h);
1079         crq->buf = buf;
1080         crq->len = PAGE_SIZE - len;
1081         crq->readers = 0;
1082         spin_lock(&queue_lock);
1083         list_add_tail(&crq->q.list, &detail->queue);
1084         spin_unlock(&queue_lock);
1085         wake_up(&queue_wait);
1086         return 0;
1087 }
1088
1089 /*
1090  * parse a message from user-space and pass it
1091  * to an appropriate cache
1092  * Messages are, like requests, separated into fields by
1093  * spaces and dequotes as \xHEXSTRING or embedded \nnn octal
1094  *
1095  * Message is
1096  *   reply cachename expiry key ... content....
1097  *
1098  * key and content are both parsed by cache
1099  */
1100
1101 #define isodigit(c) (isdigit(c) && c <= '7')
1102 int qword_get(char **bpp, char *dest, int bufsize)
1103 {
1104         /* return bytes copied, or -1 on error */
1105         char *bp = *bpp;
1106         int len = 0;
1107
1108         while (*bp == ' ') bp++;
1109
1110         if (bp[0] == '\\' && bp[1] == 'x') {
1111                 /* HEX STRING */
1112                 bp += 2;
1113                 while (isxdigit(bp[0]) && isxdigit(bp[1]) && len < bufsize) {
1114                         int byte = isdigit(*bp) ? *bp-'0' : toupper(*bp)-'A'+10;
1115                         bp++;
1116                         byte <<= 4;
1117                         byte |= isdigit(*bp) ? *bp-'0' : toupper(*bp)-'A'+10;
1118                         *dest++ = byte;
1119                         bp++;
1120                         len++;
1121                 }
1122         } else {
1123                 /* text with \nnn octal quoting */
1124                 while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) {
1125                         if (*bp == '\\' &&
1126                             isodigit(bp[1]) && (bp[1] <= '3') &&
1127                             isodigit(bp[2]) &&
1128                             isodigit(bp[3])) {
1129                                 int byte = (*++bp -'0');
1130                                 bp++;
1131                                 byte = (byte << 3) | (*bp++ - '0');
1132                                 byte = (byte << 3) | (*bp++ - '0');
1133                                 *dest++ = byte;
1134                                 len++;
1135                         } else {
1136                                 *dest++ = *bp++;
1137                                 len++;
1138                         }
1139                 }
1140         }
1141
1142         if (*bp != ' ' && *bp != '\n' && *bp != '\0')
1143                 return -1;
1144         while (*bp == ' ') bp++;
1145         *bpp = bp;
1146         *dest = '\0';
1147         return len;
1148 }
1149 EXPORT_SYMBOL(qword_get);
1150
1151
1152 /*
1153  * support /proc/sunrpc/cache/$CACHENAME/content
1154  * as a seqfile.
1155  * We call ->cache_show passing NULL for the item to
1156  * get a header, then pass each real item in the cache
1157  */
1158
1159 struct handle {
1160         struct cache_detail *cd;
1161 };
1162
1163 static void *c_start(struct seq_file *m, loff_t *pos)
1164         __acquires(cd->hash_lock)
1165 {
1166         loff_t n = *pos;
1167         unsigned hash, entry;
1168         struct cache_head *ch;
1169         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1170
1171
1172         read_lock(&cd->hash_lock);
1173         if (!n--)
1174                 return SEQ_START_TOKEN;
1175         hash = n >> 32;
1176         entry = n & ((1LL<<32) - 1);
1177
1178         for (ch=cd->hash_table[hash]; ch; ch=ch->next)
1179                 if (!entry--)
1180                         return ch;
1181         n &= ~((1LL<<32) - 1);
1182         do {
1183                 hash++;
1184                 n += 1LL<<32;
1185         } while(hash < cd->hash_size &&
1186                 cd->hash_table[hash]==NULL);
1187         if (hash >= cd->hash_size)
1188                 return NULL;
1189         *pos = n+1;
1190         return cd->hash_table[hash];
1191 }
1192
1193 static void *c_next(struct seq_file *m, void *p, loff_t *pos)
1194 {
1195         struct cache_head *ch = p;
1196         int hash = (*pos >> 32);
1197         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1198
1199         if (p == SEQ_START_TOKEN)
1200                 hash = 0;
1201         else if (ch->next == NULL) {
1202                 hash++;
1203                 *pos += 1LL<<32;
1204         } else {
1205                 ++*pos;
1206                 return ch->next;
1207         }
1208         *pos &= ~((1LL<<32) - 1);
1209         while (hash < cd->hash_size &&
1210                cd->hash_table[hash] == NULL) {
1211                 hash++;
1212                 *pos += 1LL<<32;
1213         }
1214         if (hash >= cd->hash_size)
1215                 return NULL;
1216         ++*pos;
1217         return cd->hash_table[hash];
1218 }
1219
1220 static void c_stop(struct seq_file *m, void *p)
1221         __releases(cd->hash_lock)
1222 {
1223         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1224         read_unlock(&cd->hash_lock);
1225 }
1226
1227 static int c_show(struct seq_file *m, void *p)
1228 {
1229         struct cache_head *cp = p;
1230         struct cache_detail *cd = ((struct handle*)m->private)->cd;
1231
1232         if (p == SEQ_START_TOKEN)
1233                 return cd->cache_show(m, cd, NULL);
1234
1235         ifdebug(CACHE)
1236                 seq_printf(m, "# expiry=%ld refcnt=%d flags=%lx\n",
1237                            cp->expiry_time, atomic_read(&cp->ref.refcount), cp->flags);
1238         cache_get(cp);
1239         if (cache_check(cd, cp, NULL))
1240                 /* cache_check does a cache_put on failure */
1241                 seq_printf(m, "# ");
1242         else
1243                 cache_put(cp, cd);
1244
1245         return cd->cache_show(m, cd, cp);
1246 }
1247
1248 static const struct seq_operations cache_content_op = {
1249         .start  = c_start,
1250         .next   = c_next,
1251         .stop   = c_stop,
1252         .show   = c_show,
1253 };
1254
1255 static int content_open(struct inode *inode, struct file *file)
1256 {
1257         struct handle *han;
1258         struct cache_detail *cd = PDE(inode)->data;
1259
1260         han = __seq_open_private(file, &cache_content_op, sizeof(*han));
1261         if (han == NULL)
1262                 return -ENOMEM;
1263
1264         han->cd = cd;
1265         return 0;
1266 }
1267
1268 static const struct file_operations content_file_operations = {
1269         .open           = content_open,
1270         .read           = seq_read,
1271         .llseek         = seq_lseek,
1272         .release        = seq_release_private,
1273 };
1274
1275 static ssize_t read_flush(struct file *file, char __user *buf,
1276                             size_t count, loff_t *ppos)
1277 {
1278         struct cache_detail *cd = PDE(file->f_path.dentry->d_inode)->data;
1279         char tbuf[20];
1280         unsigned long p = *ppos;
1281         size_t len;
1282
1283         sprintf(tbuf, "%lu\n", cd->flush_time);
1284         len = strlen(tbuf);
1285         if (p >= len)
1286                 return 0;
1287         len -= p;
1288         if (len > count)
1289                 len = count;
1290         if (copy_to_user(buf, (void*)(tbuf+p), len))
1291                 return -EFAULT;
1292         *ppos += len;
1293         return len;
1294 }
1295
1296 static ssize_t write_flush(struct file * file, const char __user * buf,
1297                              size_t count, loff_t *ppos)
1298 {
1299         struct cache_detail *cd = PDE(file->f_path.dentry->d_inode)->data;
1300         char tbuf[20];
1301         char *ep;
1302         long flushtime;
1303         if (*ppos || count > sizeof(tbuf)-1)
1304                 return -EINVAL;
1305         if (copy_from_user(tbuf, buf, count))
1306                 return -EFAULT;
1307         tbuf[count] = 0;
1308         flushtime = simple_strtoul(tbuf, &ep, 0);
1309         if (*ep && *ep != '\n')
1310                 return -EINVAL;
1311
1312         cd->flush_time = flushtime;
1313         cd->nextcheck = get_seconds();
1314         cache_flush();
1315
1316         *ppos += count;
1317         return count;
1318 }
1319
1320 static const struct file_operations cache_flush_operations = {
1321         .open           = nonseekable_open,
1322         .read           = read_flush,
1323         .write          = write_flush,
1324 };