git.oblomov.eu Git - linux-2.6/blob - net/sunrpc/cache.c

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