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 <linux/string_helpers.h>
  24#include <linux/uaccess.h>
  25#include <linux/poll.h>
  26#include <linux/seq_file.h>
  27#include <linux/proc_fs.h>
  28#include <linux/net.h>
  29#include <linux/workqueue.h>
  30#include <linux/mutex.h>
  31#include <linux/pagemap.h>
  32#include <asm/ioctls.h>
  33#include <linux/sunrpc/types.h>
  34#include <linux/sunrpc/cache.h>
  35#include <linux/sunrpc/stats.h>
  36#include <linux/sunrpc/rpc_pipe_fs.h>
  37#include "netns.h"
  38
  39#define  RPCDBG_FACILITY RPCDBG_CACHE
  40
  41static bool cache_defer_req(struct cache_req *req, struct cache_head *item);
  42static void cache_revisit_request(struct cache_head *item);
  43
  44static void cache_init(struct cache_head *h, struct cache_detail *detail)
  45{
  46        time_t now = seconds_since_boot();
  47        INIT_HLIST_NODE(&h->cache_list);
  48        h->flags = 0;
  49        kref_init(&h->ref);
  50        h->expiry_time = now + CACHE_NEW_EXPIRY;
  51        if (now <= detail->flush_time)
  52                /* ensure it isn't already expired */
  53                now = detail->flush_time + 1;
  54        h->last_refresh = now;
  55}
  56
  57static inline int cache_is_valid(struct cache_head *h);
  58static void cache_fresh_locked(struct cache_head *head, time_t expiry,
  59                                struct cache_detail *detail);
  60static void cache_fresh_unlocked(struct cache_head *head,
  61                                struct cache_detail *detail);
  62
  63static struct cache_head *sunrpc_cache_find_rcu(struct cache_detail *detail,
  64                                                struct cache_head *key,
  65                                                int hash)
  66{
  67        struct hlist_head *head = &detail->hash_table[hash];
  68        struct cache_head *tmp;
  69
  70        rcu_read_lock();
  71        hlist_for_each_entry_rcu(tmp, head, cache_list) {
  72                if (detail->match(tmp, key)) {
  73                        if (cache_is_expired(detail, tmp))
  74                                continue;
  75                        tmp = cache_get_rcu(tmp);
  76                        rcu_read_unlock();
  77                        return tmp;
  78                }
  79        }
  80        rcu_read_unlock();
  81        return NULL;
  82}
  83
  84static struct cache_head *sunrpc_cache_add_entry(struct cache_detail *detail,
  85                                                 struct cache_head *key,
  86                                                 int hash)
  87{
  88        struct cache_head *new, *tmp, *freeme = NULL;
  89        struct hlist_head *head = &detail->hash_table[hash];
  90
  91        new = detail->alloc();
  92        if (!new)
  93                return NULL;
  94        /* must fully initialise 'new', else
  95         * we might get lose if we need to
  96         * cache_put it soon.
  97         */
  98        cache_init(new, detail);
  99        detail->init(new, key);
 100
 101        spin_lock(&detail->hash_lock);
 102
 103        /* check if entry appeared while we slept */
 104        hlist_for_each_entry_rcu(tmp, head, cache_list) {
 105                if (detail->match(tmp, key)) {
 106                        if (cache_is_expired(detail, tmp)) {
 107                                hlist_del_init_rcu(&tmp->cache_list);
 108                                detail->entries --;
 109                                if (cache_is_valid(tmp) == -EAGAIN)
 110                                        set_bit(CACHE_NEGATIVE, &tmp->flags);
 111                                cache_fresh_locked(tmp, 0, detail);
 112                                freeme = tmp;
 113                                break;
 114                        }
 115                        cache_get(tmp);
 116                        spin_unlock(&detail->hash_lock);
 117                        cache_put(new, detail);
 118                        return tmp;
 119                }
 120        }
 121
 122        hlist_add_head_rcu(&new->cache_list, head);
 123        detail->entries++;
 124        cache_get(new);
 125        spin_unlock(&detail->hash_lock);
 126
 127        if (freeme) {
 128                cache_fresh_unlocked(freeme, detail);
 129                cache_put(freeme, detail);
 130        }
 131        return new;
 132}
 133
 134struct cache_head *sunrpc_cache_lookup_rcu(struct cache_detail *detail,
 135                                           struct cache_head *key, int hash)
 136{
 137        struct cache_head *ret;
 138
 139        ret = sunrpc_cache_find_rcu(detail, key, hash);
 140        if (ret)
 141                return ret;
 142        /* Didn't find anything, insert an empty entry */
 143        return sunrpc_cache_add_entry(detail, key, hash);
 144}
 145EXPORT_SYMBOL_GPL(sunrpc_cache_lookup_rcu);
 146
 147static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch);
 148
 149static void cache_fresh_locked(struct cache_head *head, time_t expiry,
 150                               struct cache_detail *detail)
 151{
 152        time_t now = seconds_since_boot();
 153        if (now <= detail->flush_time)
 154                /* ensure it isn't immediately treated as expired */
 155                now = detail->flush_time + 1;
 156        head->expiry_time = expiry;
 157        head->last_refresh = now;
 158        smp_wmb(); /* paired with smp_rmb() in cache_is_valid() */
 159        set_bit(CACHE_VALID, &head->flags);
 160}
 161
 162static void cache_fresh_unlocked(struct cache_head *head,
 163                                 struct cache_detail *detail)
 164{
 165        if (test_and_clear_bit(CACHE_PENDING, &head->flags)) {
 166                cache_revisit_request(head);
 167                cache_dequeue(detail, head);
 168        }
 169}
 170
 171struct cache_head *sunrpc_cache_update(struct cache_detail *detail,
 172                                       struct cache_head *new, struct cache_head *old, int hash)
 173{
 174        /* The 'old' entry is to be replaced by 'new'.
 175         * If 'old' is not VALID, we update it directly,
 176         * otherwise we need to replace it
 177         */
 178        struct cache_head *tmp;
 179
 180        if (!test_bit(CACHE_VALID, &old->flags)) {
 181                spin_lock(&detail->hash_lock);
 182                if (!test_bit(CACHE_VALID, &old->flags)) {
 183                        if (test_bit(CACHE_NEGATIVE, &new->flags))
 184                                set_bit(CACHE_NEGATIVE, &old->flags);
 185                        else
 186                                detail->update(old, new);
 187                        cache_fresh_locked(old, new->expiry_time, detail);
 188                        spin_unlock(&detail->hash_lock);
 189                        cache_fresh_unlocked(old, detail);
 190                        return old;
 191                }
 192                spin_unlock(&detail->hash_lock);
 193        }
 194        /* We need to insert a new entry */
 195        tmp = detail->alloc();
 196        if (!tmp) {
 197                cache_put(old, detail);
 198                return NULL;
 199        }
 200        cache_init(tmp, detail);
 201        detail->init(tmp, old);
 202
 203        spin_lock(&detail->hash_lock);
 204        if (test_bit(CACHE_NEGATIVE, &new->flags))
 205                set_bit(CACHE_NEGATIVE, &tmp->flags);
 206        else
 207                detail->update(tmp, new);
 208        hlist_add_head(&tmp->cache_list, &detail->hash_table[hash]);
 209        detail->entries++;
 210        cache_get(tmp);
 211        cache_fresh_locked(tmp, new->expiry_time, detail);
 212        cache_fresh_locked(old, 0, detail);
 213        spin_unlock(&detail->hash_lock);
 214        cache_fresh_unlocked(tmp, detail);
 215        cache_fresh_unlocked(old, detail);
 216        cache_put(old, detail);
 217        return tmp;
 218}
 219EXPORT_SYMBOL_GPL(sunrpc_cache_update);
 220
 221static int cache_make_upcall(struct cache_detail *cd, struct cache_head *h)
 222{
 223        if (cd->cache_upcall)
 224                return cd->cache_upcall(cd, h);
 225        return sunrpc_cache_pipe_upcall(cd, h);
 226}
 227
 228static inline int cache_is_valid(struct cache_head *h)
 229{
 230        if (!test_bit(CACHE_VALID, &h->flags))
 231                return -EAGAIN;
 232        else {
 233                /* entry is valid */
 234                if (test_bit(CACHE_NEGATIVE, &h->flags))
 235                        return -ENOENT;
 236                else {
 237                        /*
 238                         * In combination with write barrier in
 239                         * sunrpc_cache_update, ensures that anyone
 240                         * using the cache entry after this sees the
 241                         * updated contents:
 242                         */
 243                        smp_rmb();
 244                        return 0;
 245                }
 246        }
 247}
 248
 249static int try_to_negate_entry(struct cache_detail *detail, struct cache_head *h)
 250{
 251        int rv;
 252
 253        spin_lock(&detail->hash_lock);
 254        rv = cache_is_valid(h);
 255        if (rv == -EAGAIN) {
 256                set_bit(CACHE_NEGATIVE, &h->flags);
 257                cache_fresh_locked(h, seconds_since_boot()+CACHE_NEW_EXPIRY,
 258                                   detail);
 259                rv = -ENOENT;
 260        }
 261        spin_unlock(&detail->hash_lock);
 262        cache_fresh_unlocked(h, detail);
 263        return rv;
 264}
 265
 266/*
 267 * This is the generic cache management routine for all
 268 * the authentication caches.
 269 * It checks the currency of a cache item and will (later)
 270 * initiate an upcall to fill it if needed.
 271 *
 272 *
 273 * Returns 0 if the cache_head can be used, or cache_puts it and returns
 274 * -EAGAIN if upcall is pending and request has been queued
 275 * -ETIMEDOUT if upcall failed or request could not be queue or
 276 *           upcall completed but item is still invalid (implying that
 277 *           the cache item has been replaced with a newer one).
 278 * -ENOENT if cache entry was negative
 279 */
 280int cache_check(struct cache_detail *detail,
 281                    struct cache_head *h, struct cache_req *rqstp)
 282{
 283        int rv;
 284        long refresh_age, age;
 285
 286        /* First decide return status as best we can */
 287        rv = cache_is_valid(h);
 288
 289        /* now see if we want to start an upcall */
 290        refresh_age = (h->expiry_time - h->last_refresh);
 291        age = seconds_since_boot() - h->last_refresh;
 292
 293        if (rqstp == NULL) {
 294                if (rv == -EAGAIN)
 295                        rv = -ENOENT;
 296        } else if (rv == -EAGAIN ||
 297                   (h->expiry_time != 0 && age > refresh_age/2)) {
 298                dprintk("RPC:       Want update, refage=%ld, age=%ld\n",
 299                                refresh_age, age);
 300                if (!test_and_set_bit(CACHE_PENDING, &h->flags)) {
 301                        switch (cache_make_upcall(detail, h)) {
 302                        case -EINVAL:
 303                                rv = try_to_negate_entry(detail, h);
 304                                break;
 305                        case -EAGAIN:
 306                                cache_fresh_unlocked(h, detail);
 307                                break;
 308                        }
 309                }
 310        }
 311
 312        if (rv == -EAGAIN) {
 313                if (!cache_defer_req(rqstp, h)) {
 314                        /*
 315                         * Request was not deferred; handle it as best
 316                         * we can ourselves:
 317                         */
 318                        rv = cache_is_valid(h);
 319                        if (rv == -EAGAIN)
 320                                rv = -ETIMEDOUT;
 321                }
 322        }
 323        if (rv)
 324                cache_put(h, detail);
 325        return rv;
 326}
 327EXPORT_SYMBOL_GPL(cache_check);
 328
 329/*
 330 * caches need to be periodically cleaned.
 331 * For this we maintain a list of cache_detail and
 332 * a current pointer into that list and into the table
 333 * for that entry.
 334 *
 335 * Each time cache_clean is called it finds the next non-empty entry
 336 * in the current table and walks the list in that entry
 337 * looking for entries that can be removed.
 338 *
 339 * An entry gets removed if:
 340 * - The expiry is before current time
 341 * - The last_refresh time is before the flush_time for that cache
 342 *
 343 * later we might drop old entries with non-NEVER expiry if that table
 344 * is getting 'full' for some definition of 'full'
 345 *
 346 * The question of "how often to scan a table" is an interesting one
 347 * and is answered in part by the use of the "nextcheck" field in the
 348 * cache_detail.
 349 * When a scan of a table begins, the nextcheck field is set to a time
 350 * that is well into the future.
 351 * While scanning, if an expiry time is found that is earlier than the
 352 * current nextcheck time, nextcheck is set to that expiry time.
 353 * If the flush_time is ever set to a time earlier than the nextcheck
 354 * time, the nextcheck time is then set to that flush_time.
 355 *
 356 * A table is then only scanned if the current time is at least
 357 * the nextcheck time.
 358 *
 359 */
 360
 361static LIST_HEAD(cache_list);
 362static DEFINE_SPINLOCK(cache_list_lock);
 363static struct cache_detail *current_detail;
 364static int current_index;
 365
 366static void do_cache_clean(struct work_struct *work);
 367static struct delayed_work cache_cleaner;
 368
 369void sunrpc_init_cache_detail(struct cache_detail *cd)
 370{
 371        spin_lock_init(&cd->hash_lock);
 372        INIT_LIST_HEAD(&cd->queue);
 373        spin_lock(&cache_list_lock);
 374        cd->nextcheck = 0;
 375        cd->entries = 0;
 376        atomic_set(&cd->readers, 0);
 377        cd->last_close = 0;
 378        cd->last_warn = -1;
 379        list_add(&cd->others, &cache_list);
 380        spin_unlock(&cache_list_lock);
 381
 382        /* start the cleaning process */
 383        queue_delayed_work(system_power_efficient_wq, &cache_cleaner, 0);
 384}
 385EXPORT_SYMBOL_GPL(sunrpc_init_cache_detail);
 386
 387void sunrpc_destroy_cache_detail(struct cache_detail *cd)
 388{
 389        cache_purge(cd);
 390        spin_lock(&cache_list_lock);
 391        spin_lock(&cd->hash_lock);
 392        if (current_detail == cd)
 393                current_detail = NULL;
 394        list_del_init(&cd->others);
 395        spin_unlock(&cd->hash_lock);
 396        spin_unlock(&cache_list_lock);
 397        if (list_empty(&cache_list)) {
 398                /* module must be being unloaded so its safe to kill the worker */
 399                cancel_delayed_work_sync(&cache_cleaner);
 400        }
 401}
 402EXPORT_SYMBOL_GPL(sunrpc_destroy_cache_detail);
 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 > seconds_since_boot())
 431                        current_index = current_detail->hash_size;
 432                else {
 433                        current_index = 0;
 434                        current_detail->nextcheck = seconds_since_boot()+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               hlist_empty(&current_detail->hash_table[current_index]))
 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 = NULL;
 448                struct cache_detail *d;
 449                struct hlist_head *head;
 450                struct hlist_node *tmp;
 451
 452                spin_lock(&current_detail->hash_lock);
 453
 454                /* Ok, now to clean this strand */
 455
 456                head = &current_detail->hash_table[current_index];
 457                hlist_for_each_entry_safe(ch, tmp, head, cache_list) {
 458                        if (current_detail->nextcheck > ch->expiry_time)
 459                                current_detail->nextcheck = ch->expiry_time+1;
 460                        if (!cache_is_expired(current_detail, ch))
 461                                continue;
 462
 463                        hlist_del_init_rcu(&ch->cache_list);
 464                        current_detail->entries--;
 465                        rv = 1;
 466                        break;
 467                }
 468
 469                spin_unlock(&current_detail->hash_lock);
 470                d = current_detail;
 471                if (!ch)
 472                        current_index ++;
 473                spin_unlock(&cache_list_lock);
 474                if (ch) {
 475                        set_bit(CACHE_CLEANED, &ch->flags);
 476                        cache_fresh_unlocked(ch, d);
 477                        cache_put(ch, d);
 478                }
 479        } else
 480                spin_unlock(&cache_list_lock);
 481
 482        return rv;
 483}
 484
 485/*
 486 * We want to regularly clean the cache, so we need to schedule some work ...
 487 */
 488static void do_cache_clean(struct work_struct *work)
 489{
 490        int delay = 5;
 491        if (cache_clean() == -1)
 492                delay = round_jiffies_relative(30*HZ);
 493
 494        if (list_empty(&cache_list))
 495                delay = 0;
 496
 497        if (delay)
 498                queue_delayed_work(system_power_efficient_wq,
 499                                   &cache_cleaner, delay);
 500}
 501
 502
 503/*
 504 * Clean all caches promptly.  This just calls cache_clean
 505 * repeatedly until we are sure that every cache has had a chance to
 506 * be fully cleaned
 507 */
 508void cache_flush(void)
 509{
 510        while (cache_clean() != -1)
 511                cond_resched();
 512        while (cache_clean() != -1)
 513                cond_resched();
 514}
 515EXPORT_SYMBOL_GPL(cache_flush);
 516
 517void cache_purge(struct cache_detail *detail)
 518{
 519        struct cache_head *ch = NULL;
 520        struct hlist_head *head = NULL;
 521        struct hlist_node *tmp = NULL;
 522        int i = 0;
 523
 524        spin_lock(&detail->hash_lock);
 525        if (!detail->entries) {
 526                spin_unlock(&detail->hash_lock);
 527                return;
 528        }
 529
 530        dprintk("RPC: %d entries in %s cache\n", detail->entries, detail->name);
 531        for (i = 0; i < detail->hash_size; i++) {
 532                head = &detail->hash_table[i];
 533                hlist_for_each_entry_safe(ch, tmp, head, cache_list) {
 534                        hlist_del_init_rcu(&ch->cache_list);
 535                        detail->entries--;
 536
 537                        set_bit(CACHE_CLEANED, &ch->flags);
 538                        spin_unlock(&detail->hash_lock);
 539                        cache_fresh_unlocked(ch, detail);
 540                        cache_put(ch, detail);
 541                        spin_lock(&detail->hash_lock);
 542                }
 543        }
 544        spin_unlock(&detail->hash_lock);
 545}
 546EXPORT_SYMBOL_GPL(cache_purge);
 547
 548
 549/*
 550 * Deferral and Revisiting of Requests.
 551 *
 552 * If a cache lookup finds a pending entry, we
 553 * need to defer the request and revisit it later.
 554 * All deferred requests are stored in a hash table,
 555 * indexed by "struct cache_head *".
 556 * As it may be wasteful to store a whole request
 557 * structure, we allow the request to provide a
 558 * deferred form, which must contain a
 559 * 'struct cache_deferred_req'
 560 * This cache_deferred_req contains a method to allow
 561 * it to be revisited when cache info is available
 562 */
 563
 564#define DFR_HASHSIZE    (PAGE_SIZE/sizeof(struct list_head))
 565#define DFR_HASH(item)  ((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE)
 566
 567#define DFR_MAX 300     /* ??? */
 568
 569static DEFINE_SPINLOCK(cache_defer_lock);
 570static LIST_HEAD(cache_defer_list);
 571static struct hlist_head cache_defer_hash[DFR_HASHSIZE];
 572static int cache_defer_cnt;
 573
 574static void __unhash_deferred_req(struct cache_deferred_req *dreq)
 575{
 576        hlist_del_init(&dreq->hash);
 577        if (!list_empty(&dreq->recent)) {
 578                list_del_init(&dreq->recent);
 579                cache_defer_cnt--;
 580        }
 581}
 582
 583static void __hash_deferred_req(struct cache_deferred_req *dreq, struct cache_head *item)
 584{
 585        int hash = DFR_HASH(item);
 586
 587        INIT_LIST_HEAD(&dreq->recent);
 588        hlist_add_head(&dreq->hash, &cache_defer_hash[hash]);
 589}
 590
 591static void setup_deferral(struct cache_deferred_req *dreq,
 592                           struct cache_head *item,
 593                           int count_me)
 594{
 595
 596        dreq->item = item;
 597
 598        spin_lock(&cache_defer_lock);
 599
 600        __hash_deferred_req(dreq, item);
 601
 602        if (count_me) {
 603                cache_defer_cnt++;
 604                list_add(&dreq->recent, &cache_defer_list);
 605        }
 606
 607        spin_unlock(&cache_defer_lock);
 608
 609}
 610
 611struct thread_deferred_req {
 612        struct cache_deferred_req handle;
 613        struct completion completion;
 614};
 615
 616static void cache_restart_thread(struct cache_deferred_req *dreq, int too_many)
 617{
 618        struct thread_deferred_req *dr =
 619                container_of(dreq, struct thread_deferred_req, handle);
 620        complete(&dr->completion);
 621}
 622
 623static void cache_wait_req(struct cache_req *req, struct cache_head *item)
 624{
 625        struct thread_deferred_req sleeper;
 626        struct cache_deferred_req *dreq = &sleeper.handle;
 627
 628        sleeper.completion = COMPLETION_INITIALIZER_ONSTACK(sleeper.completion);
 629        dreq->revisit = cache_restart_thread;
 630
 631        setup_deferral(dreq, item, 0);
 632
 633        if (!test_bit(CACHE_PENDING, &item->flags) ||
 634            wait_for_completion_interruptible_timeout(
 635                    &sleeper.completion, req->thread_wait) <= 0) {
 636                /* The completion wasn't completed, so we need
 637                 * to clean up
 638                 */
 639                spin_lock(&cache_defer_lock);
 640                if (!hlist_unhashed(&sleeper.handle.hash)) {
 641                        __unhash_deferred_req(&sleeper.handle);
 642                        spin_unlock(&cache_defer_lock);
 643                } else {
 644                        /* cache_revisit_request already removed
 645                         * this from the hash table, but hasn't
 646                         * called ->revisit yet.  It will very soon
 647                         * and we need to wait for it.
 648                         */
 649                        spin_unlock(&cache_defer_lock);
 650                        wait_for_completion(&sleeper.completion);
 651                }
 652        }
 653}
 654
 655static void cache_limit_defers(void)
 656{
 657        /* Make sure we haven't exceed the limit of allowed deferred
 658         * requests.
 659         */
 660        struct cache_deferred_req *discard = NULL;
 661
 662        if (cache_defer_cnt <= DFR_MAX)
 663                return;
 664
 665        spin_lock(&cache_defer_lock);
 666
 667        /* Consider removing either the first or the last */
 668        if (cache_defer_cnt > DFR_MAX) {
 669                if (prandom_u32() & 1)
 670                        discard = list_entry(cache_defer_list.next,
 671                                             struct cache_deferred_req, recent);
 672                else
 673                        discard = list_entry(cache_defer_list.prev,
 674                                             struct cache_deferred_req, recent);
 675                __unhash_deferred_req(discard);
 676        }
 677        spin_unlock(&cache_defer_lock);
 678        if (discard)
 679                discard->revisit(discard, 1);
 680}
 681
 682/* Return true if and only if a deferred request is queued. */
 683static bool cache_defer_req(struct cache_req *req, struct cache_head *item)
 684{
 685        struct cache_deferred_req *dreq;
 686
 687        if (req->thread_wait) {
 688                cache_wait_req(req, item);
 689                if (!test_bit(CACHE_PENDING, &item->flags))
 690                        return false;
 691        }
 692        dreq = req->defer(req);
 693        if (dreq == NULL)
 694                return false;
 695        setup_deferral(dreq, item, 1);
 696        if (!test_bit(CACHE_PENDING, &item->flags))
 697                /* Bit could have been cleared before we managed to
 698                 * set up the deferral, so need to revisit just in case
 699                 */
 700                cache_revisit_request(item);
 701
 702        cache_limit_defers();
 703        return true;
 704}
 705
 706static void cache_revisit_request(struct cache_head *item)
 707{
 708        struct cache_deferred_req *dreq;
 709        struct list_head pending;
 710        struct hlist_node *tmp;
 711        int hash = DFR_HASH(item);
 712
 713        INIT_LIST_HEAD(&pending);
 714        spin_lock(&cache_defer_lock);
 715
 716        hlist_for_each_entry_safe(dreq, tmp, &cache_defer_hash[hash], hash)
 717                if (dreq->item == item) {
 718                        __unhash_deferred_req(dreq);
 719                        list_add(&dreq->recent, &pending);
 720                }
 721
 722        spin_unlock(&cache_defer_lock);
 723
 724        while (!list_empty(&pending)) {
 725                dreq = list_entry(pending.next, struct cache_deferred_req, recent);
 726                list_del_init(&dreq->recent);
 727                dreq->revisit(dreq, 0);
 728        }
 729}
 730
 731void cache_clean_deferred(void *owner)
 732{
 733        struct cache_deferred_req *dreq, *tmp;
 734        struct list_head pending;
 735
 736
 737        INIT_LIST_HEAD(&pending);
 738        spin_lock(&cache_defer_lock);
 739
 740        list_for_each_entry_safe(dreq, tmp, &cache_defer_list, recent) {
 741                if (dreq->owner == owner) {
 742                        __unhash_deferred_req(dreq);
 743                        list_add(&dreq->recent, &pending);
 744                }
 745        }
 746        spin_unlock(&cache_defer_lock);
 747
 748        while (!list_empty(&pending)) {
 749                dreq = list_entry(pending.next, struct cache_deferred_req, recent);
 750                list_del_init(&dreq->recent);
 751                dreq->revisit(dreq, 1);
 752        }
 753}
 754
 755/*
 756 * communicate with user-space
 757 *
 758 * We have a magic /proc file - /proc/net/rpc/<cachename>/channel.
 759 * On read, you get a full request, or block.
 760 * On write, an update request is processed.
 761 * Poll works if anything to read, and always allows write.
 762 *
 763 * Implemented by linked list of requests.  Each open file has
 764 * a ->private that also exists in this list.  New requests are added
 765 * to the end and may wakeup and preceding readers.
 766 * New readers are added to the head.  If, on read, an item is found with
 767 * CACHE_UPCALLING clear, we free it from the list.
 768 *
 769 */
 770
 771static DEFINE_SPINLOCK(queue_lock);
 772static DEFINE_MUTEX(queue_io_mutex);
 773
 774struct cache_queue {
 775        struct list_head        list;
 776        int                     reader; /* if 0, then request */
 777};
 778struct cache_request {
 779        struct cache_queue      q;
 780        struct cache_head       *item;
 781        char                    * buf;
 782        int                     len;
 783        int                     readers;
 784};
 785struct cache_reader {
 786        struct cache_queue      q;
 787        int                     offset; /* if non-0, we have a refcnt on next request */
 788};
 789
 790static int cache_request(struct cache_detail *detail,
 791                               struct cache_request *crq)
 792{
 793        char *bp = crq->buf;
 794        int len = PAGE_SIZE;
 795
 796        detail->cache_request(detail, crq->item, &bp, &len);
 797        if (len < 0)
 798                return -EAGAIN;
 799        return PAGE_SIZE - len;
 800}
 801
 802static ssize_t cache_read(struct file *filp, char __user *buf, size_t count,
 803                          loff_t *ppos, struct cache_detail *cd)
 804{
 805        struct cache_reader *rp = filp->private_data;
 806        struct cache_request *rq;
 807        struct inode *inode = file_inode(filp);
 808        int err;
 809
 810        if (count == 0)
 811                return 0;
 812
 813        inode_lock(inode); /* protect against multiple concurrent
 814                              * readers on this file */
 815 again:
 816        spin_lock(&queue_lock);
 817        /* need to find next request */
 818        while (rp->q.list.next != &cd->queue &&
 819               list_entry(rp->q.list.next, struct cache_queue, list)
 820               ->reader) {
 821                struct list_head *next = rp->q.list.next;
 822                list_move(&rp->q.list, next);
 823        }
 824        if (rp->q.list.next == &cd->queue) {
 825                spin_unlock(&queue_lock);
 826                inode_unlock(inode);
 827                WARN_ON_ONCE(rp->offset);
 828                return 0;
 829        }
 830        rq = container_of(rp->q.list.next, struct cache_request, q.list);
 831        WARN_ON_ONCE(rq->q.reader);
 832        if (rp->offset == 0)
 833                rq->readers++;
 834        spin_unlock(&queue_lock);
 835
 836        if (rq->len == 0) {
 837                err = cache_request(cd, rq);
 838                if (err < 0)
 839                        goto out;
 840                rq->len = err;
 841        }
 842
 843        if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) {
 844                err = -EAGAIN;
 845                spin_lock(&queue_lock);
 846                list_move(&rp->q.list, &rq->q.list);
 847                spin_unlock(&queue_lock);
 848        } else {
 849                if (rp->offset + count > rq->len)
 850                        count = rq->len - rp->offset;
 851                err = -EFAULT;
 852                if (copy_to_user(buf, rq->buf + rp->offset, count))
 853                        goto out;
 854                rp->offset += count;
 855                if (rp->offset >= rq->len) {
 856                        rp->offset = 0;
 857                        spin_lock(&queue_lock);
 858                        list_move(&rp->q.list, &rq->q.list);
 859                        spin_unlock(&queue_lock);
 860                }
 861                err = 0;
 862        }
 863 out:
 864        if (rp->offset == 0) {
 865                /* need to release rq */
 866                spin_lock(&queue_lock);
 867                rq->readers--;
 868                if (rq->readers == 0 &&
 869                    !test_bit(CACHE_PENDING, &rq->item->flags)) {
 870                        list_del(&rq->q.list);
 871                        spin_unlock(&queue_lock);
 872                        cache_put(rq->item, cd);
 873                        kfree(rq->buf);
 874                        kfree(rq);
 875                } else
 876                        spin_unlock(&queue_lock);
 877        }
 878        if (err == -EAGAIN)
 879                goto again;
 880        inode_unlock(inode);
 881        return err ? err :  count;
 882}
 883
 884static ssize_t cache_do_downcall(char *kaddr, const char __user *buf,
 885                                 size_t count, struct cache_detail *cd)
 886{
 887        ssize_t ret;
 888
 889        if (count == 0)
 890                return -EINVAL;
 891        if (copy_from_user(kaddr, buf, count))
 892                return -EFAULT;
 893        kaddr[count] = '\0';
 894        ret = cd->cache_parse(cd, kaddr, count);
 895        if (!ret)
 896                ret = count;
 897        return ret;
 898}
 899
 900static ssize_t cache_slow_downcall(const char __user *buf,
 901                                   size_t count, struct cache_detail *cd)
 902{
 903        static char write_buf[8192]; /* protected by queue_io_mutex */
 904        ssize_t ret = -EINVAL;
 905
 906        if (count >= sizeof(write_buf))
 907                goto out;
 908        mutex_lock(&queue_io_mutex);
 909        ret = cache_do_downcall(write_buf, buf, count, cd);
 910        mutex_unlock(&queue_io_mutex);
 911out:
 912        return ret;
 913}
 914
 915static ssize_t cache_downcall(struct address_space *mapping,
 916                              const char __user *buf,
 917                              size_t count, struct cache_detail *cd)
 918{
 919        struct page *page;
 920        char *kaddr;
 921        ssize_t ret = -ENOMEM;
 922
 923        if (count >= PAGE_SIZE)
 924                goto out_slow;
 925
 926        page = find_or_create_page(mapping, 0, GFP_KERNEL);
 927        if (!page)
 928                goto out_slow;
 929
 930        kaddr = kmap(page);
 931        ret = cache_do_downcall(kaddr, buf, count, cd);
 932        kunmap(page);
 933        unlock_page(page);
 934        put_page(page);
 935        return ret;
 936out_slow:
 937        return cache_slow_downcall(buf, count, cd);
 938}
 939
 940static ssize_t cache_write(struct file *filp, const char __user *buf,
 941                           size_t count, loff_t *ppos,
 942                           struct cache_detail *cd)
 943{
 944        struct address_space *mapping = filp->f_mapping;
 945        struct inode *inode = file_inode(filp);
 946        ssize_t ret = -EINVAL;
 947
 948        if (!cd->cache_parse)
 949                goto out;
 950
 951        inode_lock(inode);
 952        ret = cache_downcall(mapping, buf, count, cd);
 953        inode_unlock(inode);
 954out:
 955        return ret;
 956}
 957
 958static DECLARE_WAIT_QUEUE_HEAD(queue_wait);
 959
 960static __poll_t cache_poll(struct file *filp, poll_table *wait,
 961                               struct cache_detail *cd)
 962{
 963        __poll_t mask;
 964        struct cache_reader *rp = filp->private_data;
 965        struct cache_queue *cq;
 966
 967        poll_wait(filp, &queue_wait, wait);
 968
 969        /* alway allow write */
 970        mask = EPOLLOUT | EPOLLWRNORM;
 971
 972        if (!rp)
 973                return mask;
 974
 975        spin_lock(&queue_lock);
 976
 977        for (cq= &rp->q; &cq->list != &cd->queue;
 978             cq = list_entry(cq->list.next, struct cache_queue, list))
 979                if (!cq->reader) {
 980                        mask |= EPOLLIN | EPOLLRDNORM;
 981                        break;
 982                }
 983        spin_unlock(&queue_lock);
 984        return mask;
 985}
 986
 987static int cache_ioctl(struct inode *ino, struct file *filp,
 988                       unsigned int cmd, unsigned long arg,
 989                       struct cache_detail *cd)
 990{
 991        int len = 0;
 992        struct cache_reader *rp = filp->private_data;
 993        struct cache_queue *cq;
 994
 995        if (cmd != FIONREAD || !rp)
 996                return -EINVAL;
 997
 998        spin_lock(&queue_lock);
 999
1000        /* only find the length remaining in current request,
1001         * or the length of the next request
1002         */
1003        for (cq= &rp->q; &cq->list != &cd->queue;
1004             cq = list_entry(cq->list.next, struct cache_queue, list))
1005                if (!cq->reader) {
1006                        struct cache_request *cr =
1007                                container_of(cq, struct cache_request, q);
1008                        len = cr->len - rp->offset;
1009                        break;
1010                }
1011        spin_unlock(&queue_lock);
1012
1013        return put_user(len, (int __user *)arg);
1014}
1015
1016static int cache_open(struct inode *inode, struct file *filp,
1017                      struct cache_detail *cd)
1018{
1019        struct cache_reader *rp = NULL;
1020
1021        if (!cd || !try_module_get(cd->owner))
1022                return -EACCES;
1023        nonseekable_open(inode, filp);
1024        if (filp->f_mode & FMODE_READ) {
1025                rp = kmalloc(sizeof(*rp), GFP_KERNEL);
1026                if (!rp) {
1027                        module_put(cd->owner);
1028                        return -ENOMEM;
1029                }
1030                rp->offset = 0;
1031                rp->q.reader = 1;
1032                atomic_inc(&cd->readers);
1033                spin_lock(&queue_lock);
1034                list_add(&rp->q.list, &cd->queue);
1035                spin_unlock(&queue_lock);
1036        }
1037        filp->private_data = rp;
1038        return 0;
1039}
1040
1041static int cache_release(struct inode *inode, struct file *filp,
1042                         struct cache_detail *cd)
1043{
1044        struct cache_reader *rp = filp->private_data;
1045
1046        if (rp) {
1047                spin_lock(&queue_lock);
1048                if (rp->offset) {
1049                        struct cache_queue *cq;
1050                        for (cq= &rp->q; &cq->list != &cd->queue;
1051                             cq = list_entry(cq->list.next, struct cache_queue, list))
1052                                if (!cq->reader) {
1053                                        container_of(cq, struct cache_request, q)
1054                                                ->readers--;
1055                                        break;
1056                                }
1057                        rp->offset = 0;
1058                }
1059                list_del(&rp->q.list);
1060                spin_unlock(&queue_lock);
1061
1062                filp->private_data = NULL;
1063                kfree(rp);
1064
1065                cd->last_close = seconds_since_boot();
1066                atomic_dec(&cd->readers);
1067        }
1068        module_put(cd->owner);
1069        return 0;
1070}
1071
1072
1073
1074static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch)
1075{
1076        struct cache_queue *cq, *tmp;
1077        struct cache_request *cr;
1078        struct list_head dequeued;
1079
1080        INIT_LIST_HEAD(&dequeued);
1081        spin_lock(&queue_lock);
1082        list_for_each_entry_safe(cq, tmp, &detail->queue, list)
1083                if (!cq->reader) {
1084                        cr = container_of(cq, struct cache_request, q);
1085                        if (cr->item != ch)
1086                                continue;
1087                        if (test_bit(CACHE_PENDING, &ch->flags))
1088                                /* Lost a race and it is pending again */
1089                                break;
1090                        if (cr->readers != 0)
1091                                continue;
1092                        list_move(&cr->q.list, &dequeued);
1093                }
1094        spin_unlock(&queue_lock);
1095        while (!list_empty(&dequeued)) {
1096                cr = list_entry(dequeued.next, struct cache_request, q.list);
1097                list_del(&cr->q.list);
1098                cache_put(cr->item, detail);
1099                kfree(cr->buf);
1100                kfree(cr);
1101        }
1102}
1103
1104/*
1105 * Support routines for text-based upcalls.
1106 * Fields are separated by spaces.
1107 * Fields are either mangled to quote space tab newline slosh with slosh
1108 * or a hexified with a leading \x
1109 * Record is terminated with newline.
1110 *
1111 */
1112
1113void qword_add(char **bpp, int *lp, char *str)
1114{
1115        char *bp = *bpp;
1116        int len = *lp;
1117        int ret;
1118
1119        if (len < 0) return;
1120
1121        ret = string_escape_str(str, bp, len, ESCAPE_OCTAL, "\\ \n\t");
1122        if (ret >= len) {
1123                bp += len;
1124                len = -1;
1125        } else {
1126                bp += ret;
1127                len -= ret;
1128                *bp++ = ' ';
1129                len--;
1130        }
1131        *bpp = bp;
1132        *lp = len;
1133}
1134EXPORT_SYMBOL_GPL(qword_add);
1135
1136void qword_addhex(char **bpp, int *lp, char *buf, int blen)
1137{
1138        char *bp = *bpp;
1139        int len = *lp;
1140
1141        if (len < 0) return;
1142
1143        if (len > 2) {
1144                *bp++ = '\\';
1145                *bp++ = 'x';
1146                len -= 2;
1147                while (blen && len >= 2) {
1148                        bp = hex_byte_pack(bp, *buf++);
1149                        len -= 2;
1150                        blen--;
1151                }
1152        }
1153        if (blen || len<1) len = -1;
1154        else {
1155                *bp++ = ' ';
1156                len--;
1157        }
1158        *bpp = bp;
1159        *lp = len;
1160}
1161EXPORT_SYMBOL_GPL(qword_addhex);
1162
1163static void warn_no_listener(struct cache_detail *detail)
1164{
1165        if (detail->last_warn != detail->last_close) {
1166                detail->last_warn = detail->last_close;
1167                if (detail->warn_no_listener)
1168                        detail->warn_no_listener(detail, detail->last_close != 0);
1169        }
1170}
1171
1172static bool cache_listeners_exist(struct cache_detail *detail)
1173{
1174        if (atomic_read(&detail->readers))
1175                return true;
1176        if (detail->last_close == 0)
1177                /* This cache was never opened */
1178                return false;
1179        if (detail->last_close < seconds_since_boot() - 30)
1180                /*
1181                 * We allow for the possibility that someone might
1182                 * restart a userspace daemon without restarting the
1183                 * server; but after 30 seconds, we give up.
1184                 */
1185                 return false;
1186        return true;
1187}
1188
1189/*
1190 * register an upcall request to user-space and queue it up for read() by the
1191 * upcall daemon.
1192 *
1193 * Each request is at most one page long.
1194 */
1195int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h)
1196{
1197
1198        char *buf;
1199        struct cache_request *crq;
1200        int ret = 0;
1201
1202        if (!detail->cache_request)
1203                return -EINVAL;
1204
1205        if (!cache_listeners_exist(detail)) {
1206                warn_no_listener(detail);
1207                return -EINVAL;
1208        }
1209        if (test_bit(CACHE_CLEANED, &h->flags))
1210                /* Too late to make an upcall */
1211                return -EAGAIN;
1212
1213        buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
1214        if (!buf)
1215                return -EAGAIN;
1216
1217        crq = kmalloc(sizeof (*crq), GFP_KERNEL);
1218        if (!crq) {
1219                kfree(buf);
1220                return -EAGAIN;
1221        }
1222
1223        crq->q.reader = 0;
1224        crq->buf = buf;
1225        crq->len = 0;
1226        crq->readers = 0;
1227        spin_lock(&queue_lock);
1228        if (test_bit(CACHE_PENDING, &h->flags)) {
1229                crq->item = cache_get(h);
1230                list_add_tail(&crq->q.list, &detail->queue);
1231        } else
1232                /* Lost a race, no longer PENDING, so don't enqueue */
1233                ret = -EAGAIN;
1234        spin_unlock(&queue_lock);
1235        wake_up(&queue_wait);
1236        if (ret == -EAGAIN) {
1237                kfree(buf);
1238                kfree(crq);
1239        }
1240        return ret;
1241}
1242EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall);
1243
1244/*
1245 * parse a message from user-space and pass it
1246 * to an appropriate cache
1247 * Messages are, like requests, separated into fields by
1248 * spaces and dequotes as \xHEXSTRING or embedded \nnn octal
1249 *
1250 * Message is
1251 *   reply cachename expiry key ... content....
1252 *
1253 * key and content are both parsed by cache
1254 */
1255
1256int qword_get(char **bpp, char *dest, int bufsize)
1257{
1258        /* return bytes copied, or -1 on error */
1259        char *bp = *bpp;
1260        int len = 0;
1261
1262        while (*bp == ' ') bp++;
1263
1264        if (bp[0] == '\\' && bp[1] == 'x') {
1265                /* HEX STRING */
1266                bp += 2;
1267                while (len < bufsize - 1) {
1268                        int h, l;
1269
1270                        h = hex_to_bin(bp[0]);
1271                        if (h < 0)
1272                                break;
1273
1274                        l = hex_to_bin(bp[1]);
1275                        if (l < 0)
1276                                break;
1277
1278                        *dest++ = (h << 4) | l;
1279                        bp += 2;
1280                        len++;
1281                }
1282        } else {
1283                /* text with \nnn octal quoting */
1284                while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) {
1285                        if (*bp == '\\' &&
1286                            isodigit(bp[1]) && (bp[1] <= '3') &&
1287                            isodigit(bp[2]) &&
1288                            isodigit(bp[3])) {
1289                                int byte = (*++bp -'0');
1290                                bp++;
1291                                byte = (byte << 3) | (*bp++ - '0');
1292                                byte = (byte << 3) | (*bp++ - '0');
1293                                *dest++ = byte;
1294                                len++;
1295                        } else {
1296                                *dest++ = *bp++;
1297                                len++;
1298                        }
1299                }
1300        }
1301
1302        if (*bp != ' ' && *bp != '\n' && *bp != '\0')
1303                return -1;
1304        while (*bp == ' ') bp++;
1305        *bpp = bp;
1306        *dest = '\0';
1307        return len;
1308}
1309EXPORT_SYMBOL_GPL(qword_get);
1310
1311
1312/*
1313 * support /proc/net/rpc/$CACHENAME/content
1314 * as a seqfile.
1315 * We call ->cache_show passing NULL for the item to
1316 * get a header, then pass each real item in the cache
1317 */
1318
1319static void *__cache_seq_start(struct seq_file *m, loff_t *pos)
1320{
1321        loff_t n = *pos;
1322        unsigned int hash, entry;
1323        struct cache_head *ch;
1324        struct cache_detail *cd = m->private;
1325
1326        if (!n--)
1327                return SEQ_START_TOKEN;
1328        hash = n >> 32;
1329        entry = n & ((1LL<<32) - 1);
1330
1331        hlist_for_each_entry_rcu(ch, &cd->hash_table[hash], cache_list)
1332                if (!entry--)
1333                        return ch;
1334        n &= ~((1LL<<32) - 1);
1335        do {
1336                hash++;
1337                n += 1LL<<32;
1338        } while(hash < cd->hash_size &&
1339                hlist_empty(&cd->hash_table[hash]));
1340        if (hash >= cd->hash_size)
1341                return NULL;
1342        *pos = n+1;
1343        return hlist_entry_safe(rcu_dereference_raw(
1344                                hlist_first_rcu(&cd->hash_table[hash])),
1345                                struct cache_head, cache_list);
1346}
1347
1348static void *cache_seq_next(struct seq_file *m, void *p, loff_t *pos)
1349{
1350        struct cache_head *ch = p;
1351        int hash = (*pos >> 32);
1352        struct cache_detail *cd = m->private;
1353
1354        if (p == SEQ_START_TOKEN)
1355                hash = 0;
1356        else if (ch->cache_list.next == NULL) {
1357                hash++;
1358                *pos += 1LL<<32;
1359        } else {
1360                ++*pos;
1361                return hlist_entry_safe(rcu_dereference_raw(
1362                                        hlist_next_rcu(&ch->cache_list)),
1363                                        struct cache_head, cache_list);
1364        }
1365        *pos &= ~((1LL<<32) - 1);
1366        while (hash < cd->hash_size &&
1367               hlist_empty(&cd->hash_table[hash])) {
1368                hash++;
1369                *pos += 1LL<<32;
1370        }
1371        if (hash >= cd->hash_size)
1372                return NULL;
1373        ++*pos;
1374        return hlist_entry_safe(rcu_dereference_raw(
1375                                hlist_first_rcu(&cd->hash_table[hash])),
1376                                struct cache_head, cache_list);
1377}
1378EXPORT_SYMBOL_GPL(cache_seq_next);
1379
1380void *cache_seq_start_rcu(struct seq_file *m, loff_t *pos)
1381        __acquires(RCU)
1382{
1383        rcu_read_lock();
1384        return __cache_seq_start(m, pos);
1385}
1386EXPORT_SYMBOL_GPL(cache_seq_start_rcu);
1387
1388void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos)
1389{
1390        return cache_seq_next(file, p, pos);
1391}
1392EXPORT_SYMBOL_GPL(cache_seq_next_rcu);
1393
1394void cache_seq_stop_rcu(struct seq_file *m, void *p)
1395        __releases(RCU)
1396{
1397        rcu_read_unlock();
1398}
1399EXPORT_SYMBOL_GPL(cache_seq_stop_rcu);
1400
1401static int c_show(struct seq_file *m, void *p)
1402{
1403        struct cache_head *cp = p;
1404        struct cache_detail *cd = m->private;
1405
1406        if (p == SEQ_START_TOKEN)
1407                return cd->cache_show(m, cd, NULL);
1408
1409        ifdebug(CACHE)
1410                seq_printf(m, "# expiry=%ld refcnt=%d flags=%lx\n",
1411                           convert_to_wallclock(cp->expiry_time),
1412                           kref_read(&cp->ref), cp->flags);
1413        cache_get(cp);
1414        if (cache_check(cd, cp, NULL))
1415                /* cache_check does a cache_put on failure */
1416                seq_printf(m, "# ");
1417        else {
1418                if (cache_is_expired(cd, cp))
1419                        seq_printf(m, "# ");
1420                cache_put(cp, cd);
1421        }
1422
1423        return cd->cache_show(m, cd, cp);
1424}
1425
1426static const struct seq_operations cache_content_op = {
1427        .start  = cache_seq_start_rcu,
1428        .next   = cache_seq_next_rcu,
1429        .stop   = cache_seq_stop_rcu,
1430        .show   = c_show,
1431};
1432
1433static int content_open(struct inode *inode, struct file *file,
1434                        struct cache_detail *cd)
1435{
1436        struct seq_file *seq;
1437        int err;
1438
1439        if (!cd || !try_module_get(cd->owner))
1440                return -EACCES;
1441
1442        err = seq_open(file, &cache_content_op);
1443        if (err) {
1444                module_put(cd->owner);
1445                return err;
1446        }
1447
1448        seq = file->private_data;
1449        seq->private = cd;
1450        return 0;
1451}
1452
1453static int content_release(struct inode *inode, struct file *file,
1454                struct cache_detail *cd)
1455{
1456        int ret = seq_release(inode, file);
1457        module_put(cd->owner);
1458        return ret;
1459}
1460
1461static int open_flush(struct inode *inode, struct file *file,
1462                        struct cache_detail *cd)
1463{
1464        if (!cd || !try_module_get(cd->owner))
1465                return -EACCES;
1466        return nonseekable_open(inode, file);
1467}
1468
1469static int release_flush(struct inode *inode, struct file *file,
1470                        struct cache_detail *cd)
1471{
1472        module_put(cd->owner);
1473        return 0;
1474}
1475
1476static ssize_t read_flush(struct file *file, char __user *buf,
1477                          size_t count, loff_t *ppos,
1478                          struct cache_detail *cd)
1479{
1480        char tbuf[22];
1481        size_t len;
1482
1483        len = snprintf(tbuf, sizeof(tbuf), "%lu\n",
1484                        convert_to_wallclock(cd->flush_time));
1485        return simple_read_from_buffer(buf, count, ppos, tbuf, len);
1486}
1487
1488static ssize_t write_flush(struct file *file, const char __user *buf,
1489                           size_t count, loff_t *ppos,
1490                           struct cache_detail *cd)
1491{
1492        char tbuf[20];
1493        char *ep;
1494        time_t now;
1495
1496        if (*ppos || count > sizeof(tbuf)-1)
1497                return -EINVAL;
1498        if (copy_from_user(tbuf, buf, count))
1499                return -EFAULT;
1500        tbuf[count] = 0;
1501        simple_strtoul(tbuf, &ep, 0);
1502        if (*ep && *ep != '\n')
1503                return -EINVAL;
1504        /* Note that while we check that 'buf' holds a valid number,
1505         * we always ignore the value and just flush everything.
1506         * Making use of the number leads to races.
1507         */
1508
1509        now = seconds_since_boot();
1510        /* Always flush everything, so behave like cache_purge()
1511         * Do this by advancing flush_time to the current time,
1512         * or by one second if it has already reached the current time.
1513         * Newly added cache entries will always have ->last_refresh greater
1514         * that ->flush_time, so they don't get flushed prematurely.
1515         */
1516
1517        if (cd->flush_time >= now)
1518                now = cd->flush_time + 1;
1519
1520        cd->flush_time = now;
1521        cd->nextcheck = now;
1522        cache_flush();
1523
1524        *ppos += count;
1525        return count;
1526}
1527
1528static ssize_t cache_read_procfs(struct file *filp, char __user *buf,
1529                                 size_t count, loff_t *ppos)
1530{
1531        struct cache_detail *cd = PDE_DATA(file_inode(filp));
1532
1533        return cache_read(filp, buf, count, ppos, cd);
1534}
1535
1536static ssize_t cache_write_procfs(struct file *filp, const char __user *buf,
1537                                  size_t count, loff_t *ppos)
1538{
1539        struct cache_detail *cd = PDE_DATA(file_inode(filp));
1540
1541        return cache_write(filp, buf, count, ppos, cd);
1542}
1543
1544static __poll_t cache_poll_procfs(struct file *filp, poll_table *wait)
1545{
1546        struct cache_detail *cd = PDE_DATA(file_inode(filp));
1547
1548        return cache_poll(filp, wait, cd);
1549}
1550
1551static long cache_ioctl_procfs(struct file *filp,
1552                               unsigned int cmd, unsigned long arg)
1553{
1554        struct inode *inode = file_inode(filp);
1555        struct cache_detail *cd = PDE_DATA(inode);
1556
1557        return cache_ioctl(inode, filp, cmd, arg, cd);
1558}
1559
1560static int cache_open_procfs(struct inode *inode, struct file *filp)
1561{
1562        struct cache_detail *cd = PDE_DATA(inode);
1563
1564        return cache_open(inode, filp, cd);
1565}
1566
1567static int cache_release_procfs(struct inode *inode, struct file *filp)
1568{
1569        struct cache_detail *cd = PDE_DATA(inode);
1570
1571        return cache_release(inode, filp, cd);
1572}
1573
1574static const struct file_operations cache_file_operations_procfs = {
1575        .owner          = THIS_MODULE,
1576        .llseek         = no_llseek,
1577        .read           = cache_read_procfs,
1578        .write          = cache_write_procfs,
1579        .poll           = cache_poll_procfs,
1580        .unlocked_ioctl = cache_ioctl_procfs, /* for FIONREAD */
1581        .open           = cache_open_procfs,
1582        .release        = cache_release_procfs,
1583};
1584
1585static int content_open_procfs(struct inode *inode, struct file *filp)
1586{
1587        struct cache_detail *cd = PDE_DATA(inode);
1588
1589        return content_open(inode, filp, cd);
1590}
1591
1592static int content_release_procfs(struct inode *inode, struct file *filp)
1593{
1594        struct cache_detail *cd = PDE_DATA(inode);
1595
1596        return content_release(inode, filp, cd);
1597}
1598
1599static const struct file_operations content_file_operations_procfs = {
1600        .open           = content_open_procfs,
1601        .read           = seq_read,
1602        .llseek         = seq_lseek,
1603        .release        = content_release_procfs,
1604};
1605
1606static int open_flush_procfs(struct inode *inode, struct file *filp)
1607{
1608        struct cache_detail *cd = PDE_DATA(inode);
1609
1610        return open_flush(inode, filp, cd);
1611}
1612
1613static int release_flush_procfs(struct inode *inode, struct file *filp)
1614{
1615        struct cache_detail *cd = PDE_DATA(inode);
1616
1617        return release_flush(inode, filp, cd);
1618}
1619
1620static ssize_t read_flush_procfs(struct file *filp, char __user *buf,
1621                            size_t count, loff_t *ppos)
1622{
1623        struct cache_detail *cd = PDE_DATA(file_inode(filp));
1624
1625        return read_flush(filp, buf, count, ppos, cd);
1626}
1627
1628static ssize_t write_flush_procfs(struct file *filp,
1629                                  const char __user *buf,
1630                                  size_t count, loff_t *ppos)
1631{
1632        struct cache_detail *cd = PDE_DATA(file_inode(filp));
1633
1634        return write_flush(filp, buf, count, ppos, cd);
1635}
1636
1637static const struct file_operations cache_flush_operations_procfs = {
1638        .open           = open_flush_procfs,
1639        .read           = read_flush_procfs,
1640        .write          = write_flush_procfs,
1641        .release        = release_flush_procfs,
1642        .llseek         = no_llseek,
1643};
1644
1645static void remove_cache_proc_entries(struct cache_detail *cd)
1646{
1647        if (cd->procfs) {
1648                proc_remove(cd->procfs);
1649                cd->procfs = NULL;
1650        }
1651}
1652
1653#ifdef CONFIG_PROC_FS
1654static int create_cache_proc_entries(struct cache_detail *cd, struct net *net)
1655{
1656        struct proc_dir_entry *p;
1657        struct sunrpc_net *sn;
1658
1659        sn = net_generic(net, sunrpc_net_id);
1660        cd->procfs = proc_mkdir(cd->name, sn->proc_net_rpc);
1661        if (cd->procfs == NULL)
1662                goto out_nomem;
1663
1664        p = proc_create_data("flush", S_IFREG | 0600,
1665                             cd->procfs, &cache_flush_operations_procfs, cd);
1666        if (p == NULL)
1667                goto out_nomem;
1668
1669        if (cd->cache_request || cd->cache_parse) {
1670                p = proc_create_data("channel", S_IFREG | 0600, cd->procfs,
1671                                     &cache_file_operations_procfs, cd);
1672                if (p == NULL)
1673                        goto out_nomem;
1674        }
1675        if (cd->cache_show) {
1676                p = proc_create_data("content", S_IFREG | 0400, cd->procfs,
1677                                     &content_file_operations_procfs, cd);
1678                if (p == NULL)
1679                        goto out_nomem;
1680        }
1681        return 0;
1682out_nomem:
1683        remove_cache_proc_entries(cd);
1684        return -ENOMEM;
1685}
1686#else /* CONFIG_PROC_FS */
1687static int create_cache_proc_entries(struct cache_detail *cd, struct net *net)
1688{
1689        return 0;
1690}
1691#endif
1692
1693void __init cache_initialize(void)
1694{
1695        INIT_DEFERRABLE_WORK(&cache_cleaner, do_cache_clean);
1696}
1697
1698int cache_register_net(struct cache_detail *cd, struct net *net)
1699{
1700        int ret;
1701
1702        sunrpc_init_cache_detail(cd);
1703        ret = create_cache_proc_entries(cd, net);
1704        if (ret)
1705                sunrpc_destroy_cache_detail(cd);
1706        return ret;
1707}
1708EXPORT_SYMBOL_GPL(cache_register_net);
1709
1710void cache_unregister_net(struct cache_detail *cd, struct net *net)
1711{
1712        remove_cache_proc_entries(cd);
1713        sunrpc_destroy_cache_detail(cd);
1714}
1715EXPORT_SYMBOL_GPL(cache_unregister_net);
1716
1717struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net)
1718{
1719        struct cache_detail *cd;
1720        int i;
1721
1722        cd = kmemdup(tmpl, sizeof(struct cache_detail), GFP_KERNEL);
1723        if (cd == NULL)
1724                return ERR_PTR(-ENOMEM);
1725
1726        cd->hash_table = kcalloc(cd->hash_size, sizeof(struct hlist_head),
1727                                 GFP_KERNEL);
1728        if (cd->hash_table == NULL) {
1729                kfree(cd);
1730                return ERR_PTR(-ENOMEM);
1731        }
1732
1733        for (i = 0; i < cd->hash_size; i++)
1734                INIT_HLIST_HEAD(&cd->hash_table[i]);
1735        cd->net = net;
1736        return cd;
1737}
1738EXPORT_SYMBOL_GPL(cache_create_net);
1739
1740void cache_destroy_net(struct cache_detail *cd, struct net *net)
1741{
1742        kfree(cd->hash_table);
1743        kfree(cd);
1744}
1745EXPORT_SYMBOL_GPL(cache_destroy_net);
1746
1747static ssize_t cache_read_pipefs(struct file *filp, char __user *buf,
1748                                 size_t count, loff_t *ppos)
1749{
1750        struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1751
1752        return cache_read(filp, buf, count, ppos, cd);
1753}
1754
1755static ssize_t cache_write_pipefs(struct file *filp, const char __user *buf,
1756                                  size_t count, loff_t *ppos)
1757{
1758        struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1759
1760        return cache_write(filp, buf, count, ppos, cd);
1761}
1762
1763static __poll_t cache_poll_pipefs(struct file *filp, poll_table *wait)
1764{
1765        struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1766
1767        return cache_poll(filp, wait, cd);
1768}
1769
1770static long cache_ioctl_pipefs(struct file *filp,
1771                              unsigned int cmd, unsigned long arg)
1772{
1773        struct inode *inode = file_inode(filp);
1774        struct cache_detail *cd = RPC_I(inode)->private;
1775
1776        return cache_ioctl(inode, filp, cmd, arg, cd);
1777}
1778
1779static int cache_open_pipefs(struct inode *inode, struct file *filp)
1780{
1781        struct cache_detail *cd = RPC_I(inode)->private;
1782
1783        return cache_open(inode, filp, cd);
1784}
1785
1786static int cache_release_pipefs(struct inode *inode, struct file *filp)
1787{
1788        struct cache_detail *cd = RPC_I(inode)->private;
1789
1790        return cache_release(inode, filp, cd);
1791}
1792
1793const struct file_operations cache_file_operations_pipefs = {
1794        .owner          = THIS_MODULE,
1795        .llseek         = no_llseek,
1796        .read           = cache_read_pipefs,
1797        .write          = cache_write_pipefs,
1798        .poll           = cache_poll_pipefs,
1799        .unlocked_ioctl = cache_ioctl_pipefs, /* for FIONREAD */
1800        .open           = cache_open_pipefs,
1801        .release        = cache_release_pipefs,
1802};
1803
1804static int content_open_pipefs(struct inode *inode, struct file *filp)
1805{
1806        struct cache_detail *cd = RPC_I(inode)->private;
1807
1808        return content_open(inode, filp, cd);
1809}
1810
1811static int content_release_pipefs(struct inode *inode, struct file *filp)
1812{
1813        struct cache_detail *cd = RPC_I(inode)->private;
1814
1815        return content_release(inode, filp, cd);
1816}
1817
1818const struct file_operations content_file_operations_pipefs = {
1819        .open           = content_open_pipefs,
1820        .read           = seq_read,
1821        .llseek         = seq_lseek,
1822        .release        = content_release_pipefs,
1823};
1824
1825static int open_flush_pipefs(struct inode *inode, struct file *filp)
1826{
1827        struct cache_detail *cd = RPC_I(inode)->private;
1828
1829        return open_flush(inode, filp, cd);
1830}
1831
1832static int release_flush_pipefs(struct inode *inode, struct file *filp)
1833{
1834        struct cache_detail *cd = RPC_I(inode)->private;
1835
1836        return release_flush(inode, filp, cd);
1837}
1838
1839static ssize_t read_flush_pipefs(struct file *filp, char __user *buf,
1840                            size_t count, loff_t *ppos)
1841{
1842        struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1843
1844        return read_flush(filp, buf, count, ppos, cd);
1845}
1846
1847static ssize_t write_flush_pipefs(struct file *filp,
1848                                  const char __user *buf,
1849                                  size_t count, loff_t *ppos)
1850{
1851        struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1852
1853        return write_flush(filp, buf, count, ppos, cd);
1854}
1855
1856const struct file_operations cache_flush_operations_pipefs = {
1857        .open           = open_flush_pipefs,
1858        .read           = read_flush_pipefs,
1859        .write          = write_flush_pipefs,
1860        .release        = release_flush_pipefs,
1861        .llseek         = no_llseek,
1862};
1863
1864int sunrpc_cache_register_pipefs(struct dentry *parent,
1865                                 const char *name, umode_t umode,
1866                                 struct cache_detail *cd)
1867{
1868        struct dentry *dir = rpc_create_cache_dir(parent, name, umode, cd);
1869        if (IS_ERR(dir))
1870                return PTR_ERR(dir);
1871        cd->pipefs = dir;
1872        return 0;
1873}
1874EXPORT_SYMBOL_GPL(sunrpc_cache_register_pipefs);
1875
1876void sunrpc_cache_unregister_pipefs(struct cache_detail *cd)
1877{
1878        if (cd->pipefs) {
1879                rpc_remove_cache_dir(cd->pipefs);
1880                cd->pipefs = NULL;
1881        }
1882}
1883EXPORT_SYMBOL_GPL(sunrpc_cache_unregister_pipefs);
1884
1885void sunrpc_cache_unhash(struct cache_detail *cd, struct cache_head *h)
1886{
1887        spin_lock(&cd->hash_lock);
1888        if (!hlist_unhashed(&h->cache_list)){
1889                hlist_del_init_rcu(&h->cache_list);
1890                cd->entries--;
1891                spin_unlock(&cd->hash_lock);
1892                cache_put(h, cd);
1893        } else
1894                spin_unlock(&cd->hash_lock);
1895}
1896EXPORT_SYMBOL_GPL(sunrpc_cache_unhash);
1897