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