linux/net/sunrpc/cache.c
<<
>>
Prefs
   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
  37static int cache_defer_req(struct cache_req *req, struct cache_head *item);
  38static void cache_revisit_request(struct cache_head *item);
  39
  40static 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
  50struct 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}
 101EXPORT_SYMBOL(sunrpc_cache_lookup);
 102
 103
 104static void queue_loose(struct cache_detail *detail, struct cache_head *ch);
 105
 106static 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
 113static 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
 124struct 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}
 176EXPORT_SYMBOL(sunrpc_cache_update);
 177
 178static 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 */
 191int 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}
 248EXPORT_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
 282static LIST_HEAD(cache_list);
 283static DEFINE_SPINLOCK(cache_list_lock);
 284static struct cache_detail *current_detail;
 285static int current_index;
 286
 287static const struct file_operations cache_file_operations;
 288static const struct file_operations content_file_operations;
 289static const struct file_operations cache_flush_operations;
 290
 291static void do_cache_clean(struct work_struct *work);
 292static DECLARE_DELAYED_WORK(cache_cleaner, do_cache_clean);
 293
 294static 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
 309static 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;
 343out_nomem:
 344        remove_cache_proc_entries(cd);
 345        return -ENOMEM;
 346}
 347#else /* CONFIG_PROC_FS */
 348static int create_cache_proc_entries(struct cache_detail *cd)
 349{
 350        return 0;
 351}
 352#endif
 353
 354int 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}
 376EXPORT_SYMBOL(cache_register);
 377
 378void 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;
 399out:
 400        printk(KERN_ERR "nfsd: failed to unregister %s cache\n", cd->name);
 401}
 402EXPORT_SYMBOL(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 */
 410static 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 */
 491static 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 */
 510void cache_flush(void)
 511{
 512        while (cache_clean() != -1)
 513                cond_resched();
 514        while (cache_clean() != -1)
 515                cond_resched();
 516}
 517EXPORT_SYMBOL(cache_flush);
 518
 519void 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}
 526EXPORT_SYMBOL(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
 549static DEFINE_SPINLOCK(cache_defer_lock);
 550static LIST_HEAD(cache_defer_list);
 551static struct list_head cache_defer_hash[DFR_HASHSIZE];
 552static int cache_defer_cnt;
 553
 554static 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
 602static 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
 634void 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
 675static DEFINE_SPINLOCK(queue_lock);
 676static DEFINE_MUTEX(queue_io_mutex);
 677
 678struct cache_queue {
 679        struct list_head        list;
 680        int                     reader; /* if 0, then request */
 681};
 682struct cache_request {
 683        struct cache_queue      q;
 684        struct cache_head       *item;
 685        char                    * buf;
 686        int                     len;
 687        int                     readers;
 688};
 689struct cache_reader {
 690        struct cache_queue      q;
 691        int                     offset; /* if non-0, we have a refcnt on next request */
 692};
 693
 694static ssize_t
 695cache_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
 769static char write_buf[8192]; /* protected by queue_io_mutex */
 770
 771static ssize_t
 772cache_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
 799static DECLARE_WAIT_QUEUE_HEAD(queue_wait);
 800
 801static unsigned int
 802cache_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
 829static int
 830cache_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
 859static int
 860cache_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
 882static int
 883cache_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
 915static 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
 927static 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
 957void 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}
 991EXPORT_SYMBOL(qword_add);
 992
 993void 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}
1020EXPORT_SYMBOL(qword_addhex);
1021
1022static 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 */
1035static 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')
1096int 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}
1143EXPORT_SYMBOL(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
1153struct handle {
1154        struct cache_detail *cd;
1155};
1156
1157static 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
1187static 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
1214static 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
1221static 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
1242static 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
1249static 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
1262static 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
1269static 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
1290static 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
1314static const struct file_operations cache_flush_operations = {
1315        .open           = nonseekable_open,
1316        .read           = read_flush,
1317        .write          = write_flush,
1318};
1319
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.