linux/net/sunrpc/cache.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * net/sunrpc/cache.c
   4 *
   5 * Generic code for various authentication-related caches
   6 * used by sunrpc clients and servers.
   7 *
   8 * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
   9 */
  10
  11#include <linux/types.h>
  12#include <linux/fs.h>
  13#include <linux/file.h>
  14#include <linux/slab.h>
  15#include <linux/signal.h>
  16#include <linux/sched.h>
  17#include <linux/kmod.h>
  18#include <linux/list.h>
  19#include <linux/module.h>
  20#include <linux/ctype.h>
  21#include <linux/string_helpers.h>
  22#include <linux/uaccess.h>
  23#include <linux/poll.h>
  24#include <linux/seq_file.h>
  25#include <linux/proc_fs.h>
  26#include <linux/net.h>
  27#include <linux/workqueue.h>
  28#include <linux/mutex.h>
  29#include <linux/pagemap.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#include <linux/sunrpc/rpc_pipe_fs.h>
  35#include "netns.h"
  36
  37#define  RPCDBG_FACILITY RPCDBG_CACHE
  38
  39static bool cache_defer_req(struct cache_req *req, struct cache_head *item);
  40static void cache_revisit_request(struct cache_head *item);
  41static bool cache_listeners_exist(struct cache_detail *detail);
  42
  43static void cache_init(struct cache_head *h, struct cache_detail *detail)
  44{
  45        time_t now = seconds_since_boot();
  46        INIT_HLIST_NODE(&h->cache_list);
  47        h->flags = 0;
  48        kref_init(&h->ref);
  49        h->expiry_time = now + CACHE_NEW_EXPIRY;
  50        if (now <= detail->flush_time)
  51                /* ensure it isn't already expired */
  52                now = detail->flush_time + 1;
  53        h->last_refresh = now;
  54}
  55
  56static inline int cache_is_valid(struct cache_head *h);
  57static void cache_fresh_locked(struct cache_head *head, time_t expiry,
  58                                struct cache_detail *detail);
  59static void cache_fresh_unlocked(struct cache_head *head,
  60                                struct cache_detail *detail);
  61
  62static struct cache_head *sunrpc_cache_find_rcu(struct cache_detail *detail,
  63                                                struct cache_head *key,
  64                                                int hash)
  65{
  66        struct hlist_head *head = &detail->hash_table[hash];
  67        struct cache_head *tmp;
  68
  69        rcu_read_lock();
  70        hlist_for_each_entry_rcu(tmp, head, cache_list) {
  71                if (detail->match(tmp, key)) {
  72                        if (cache_is_expired(detail, tmp))
  73                                continue;
  74                        tmp = cache_get_rcu(tmp);
  75                        rcu_read_unlock();
  76                        return tmp;
  77                }
  78        }
  79        rcu_read_unlock();
  80        return NULL;
  81}
  82
  83static struct cache_head *sunrpc_cache_add_entry(struct cache_detail *detail,
  84                                                 struct cache_head *key,
  85                                                 int hash)
  86{
  87        struct cache_head *new, *tmp, *freeme = NULL;
  88        struct hlist_head *head = &detail->hash_table[hash];
  89
  90        new = detail->alloc();
  91        if (!new)
  92                return NULL;
  93        /* must fully initialise 'new', else
  94         * we might get lose if we need to
  95         * cache_put it soon.
  96         */
  97        cache_init(new, detail);
  98        detail->init(new, key);
  99
 100        spin_lock(&detail->hash_lock);
 101
 102        /* check if entry appeared while we slept */
 103        hlist_for_each_entry_rcu(tmp, head, cache_list) {
 104                if (detail->match(tmp, key)) {
 105                        if (cache_is_expired(detail, tmp)) {
 106                                hlist_del_init_rcu(&tmp->cache_list);
 107                                detail->entries --;
 108                                if (cache_is_valid(tmp) == -EAGAIN)
 109                                        set_bit(CACHE_NEGATIVE, &tmp->flags);
 110                                cache_fresh_locked(tmp, 0, detail);
 111                                freeme = tmp;
 112                                break;
 113                        }
 114                        cache_get(tmp);
 115                        spin_unlock(&detail->hash_lock);
 116                        cache_put(new, detail);
 117                        return tmp;
 118                }
 119        }
 120
 121        hlist_add_head_rcu(&new->cache_list, head);
 122        detail->entries++;
 123        cache_get(new);
 124        spin_unlock(&detail->hash_lock);
 125
 126        if (freeme) {
 127                cache_fresh_unlocked(freeme, detail);
 128                cache_put(freeme, detail);
 129        }
 130        return new;
 131}
 132
 133struct cache_head *sunrpc_cache_lookup_rcu(struct cache_detail *detail,
 134                                           struct cache_head *key, int hash)
 135{
 136        struct cache_head *ret;
 137
 138        ret = sunrpc_cache_find_rcu(detail, key, hash);
 139        if (ret)
 140                return ret;
 141        /* Didn't find anything, insert an empty entry */
 142        return sunrpc_cache_add_entry(detail, key, hash);
 143}
 144EXPORT_SYMBOL_GPL(sunrpc_cache_lookup_rcu);
 145
 146static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch);
 147
 148static void cache_fresh_locked(struct cache_head *head, time_t expiry,
 149                               struct cache_detail *detail)
 150{
 151        time_t now = seconds_since_boot();
 152        if (now <= detail->flush_time)
 153                /* ensure it isn't immediately treated as expired */
 154                now = detail->flush_time + 1;
 155        head->expiry_time = expiry;
 156        head->last_refresh = now;
 157        smp_wmb(); /* paired with smp_rmb() in cache_is_valid() */
 158        set_bit(CACHE_VALID, &head->flags);
 159}
 160
 161static void cache_fresh_unlocked(struct cache_head *head,
 162                                 struct cache_detail *detail)
 163{
 164        if (test_and_clear_bit(CACHE_PENDING, &head->flags)) {
 165                cache_revisit_request(head);
 166                cache_dequeue(detail, head);
 167        }
 168}
 169
 170struct cache_head *sunrpc_cache_update(struct cache_detail *detail,
 171                                       struct cache_head *new, struct cache_head *old, int hash)
 172{
 173        /* The 'old' entry is to be replaced by 'new'.
 174         * If 'old' is not VALID, we update it directly,
 175         * otherwise we need to replace it
 176         */
 177        struct cache_head *tmp;
 178
 179        if (!test_bit(CACHE_VALID, &old->flags)) {
 180                spin_lock(&detail->hash_lock);
 181                if (!test_bit(CACHE_VALID, &old->flags)) {
 182                        if (test_bit(CACHE_NEGATIVE, &new->flags))
 183                                set_bit(CACHE_NEGATIVE, &old->flags);
 184                        else
 185                                detail->update(old, new);
 186                        cache_fresh_locked(old, new->expiry_time, detail);
 187                        spin_unlock(&detail->hash_lock);
 188                        cache_fresh_unlocked(old, detail);
 189                        return old;
 190                }
 191                spin_unlock(&detail->hash_lock);
 192        }
 193        /* We need to insert a new entry */
 194        tmp = detail->alloc();
 195        if (!tmp) {
 196                cache_put(old, detail);
 197                return NULL;
 198        }
 199        cache_init(tmp, detail);
 200        detail->init(tmp, old);
 201
 202        spin_lock(&detail->hash_lock);
 203        if (test_bit(CACHE_NEGATIVE, &new->flags))
 204                set_bit(CACHE_NEGATIVE, &tmp->flags);
 205        else
 206                detail->update(tmp, new);
 207        hlist_add_head(&tmp->cache_list, &detail->hash_table[hash]);
 208        detail->entries++;
 209        cache_get(tmp);
 210        cache_fresh_locked(tmp, new->expiry_time, detail);
 211        cache_fresh_locked(old, 0, detail);
 212        spin_unlock(&detail->hash_lock);
 213        cache_fresh_unlocked(tmp, detail);
 214        cache_fresh_unlocked(old, detail);
 215        cache_put(old, detail);
 216        return tmp;
 217}
 218EXPORT_SYMBOL_GPL(sunrpc_cache_update);
 219
 220static int cache_make_upcall(struct cache_detail *cd, struct cache_head *h)
 221{
 222        if (cd->cache_upcall)
 223                return cd->cache_upcall(cd, h);
 224        return sunrpc_cache_pipe_upcall(cd, h);
 225}
 226
 227static inline int cache_is_valid(struct cache_head *h)
 228{
 229        if (!test_bit(CACHE_VALID, &h->flags))
 230                return -EAGAIN;
 231        else {
 232                /* entry is valid */
 233                if (test_bit(CACHE_NEGATIVE, &h->flags))
 234                        return -ENOENT;
 235                else {
 236                        /*
 237                         * In combination with write barrier in
 238                         * sunrpc_cache_update, ensures that anyone
 239                         * using the cache entry after this sees the
 240                         * updated contents:
 241                         */
 242                        smp_rmb();
 243                        return 0;
 244                }
 245        }
 246}
 247
 248static int try_to_negate_entry(struct cache_detail *detail, struct cache_head *h)
 249{
 250        int rv;
 251
 252        spin_lock(&detail->hash_lock);
 253        rv = cache_is_valid(h);
 254        if (rv == -EAGAIN) {
 255                set_bit(CACHE_NEGATIVE, &h->flags);
 256                cache_fresh_locked(h, seconds_since_boot()+CACHE_NEW_EXPIRY,
 257                                   detail);
 258                rv = -ENOENT;
 259        }
 260        spin_unlock(&detail->hash_lock);
 261        cache_fresh_unlocked(h, detail);
 262        return rv;
 263}
 264
 265/*
 266 * This is the generic cache management routine for all
 267 * the authentication caches.
 268 * It checks the currency of a cache item and will (later)
 269 * initiate an upcall to fill it if needed.
 270 *
 271 *
 272 * Returns 0 if the cache_head can be used, or cache_puts it and returns
 273 * -EAGAIN if upcall is pending and request has been queued
 274 * -ETIMEDOUT if upcall failed or request could not be queue or
 275 *           upcall completed but item is still invalid (implying that
 276 *           the cache item has been replaced with a newer one).
 277 * -ENOENT if cache entry was negative
 278 */
 279int cache_check(struct cache_detail *detail,
 280                    struct cache_head *h, struct cache_req *rqstp)
 281{
 282        int rv;
 283        long refresh_age, age;
 284
 285        /* First decide return status as best we can */
 286        rv = cache_is_valid(h);
 287
 288        /* now see if we want to start an upcall */
 289        refresh_age = (h->expiry_time - h->last_refresh);
 290        age = seconds_since_boot() - h->last_refresh;
 291
 292        if (rqstp == NULL) {
 293                if (rv == -EAGAIN)
 294                        rv = -ENOENT;
 295        } else if (rv == -EAGAIN ||
 296                   (h->expiry_time != 0 && age > refresh_age/2)) {
 297                dprintk("RPC:       Want update, refage=%ld, age=%ld\n",
 298                                refresh_age, age);
 299                if (!test_and_set_bit(CACHE_PENDING, &h->flags)) {
 300                        switch (cache_make_upcall(detail, h)) {
 301                        case -EINVAL:
 302                                rv = try_to_negate_entry(detail, h);
 303                                break;
 304                        case -EAGAIN:
 305                                cache_fresh_unlocked(h, detail);
 306                                break;
 307                        }
 308                } else if (!cache_listeners_exist(detail))
 309                        rv = try_to_negate_entry(detail, h);
 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->writers, 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
1033                spin_lock(&queue_lock);
1034                list_add(&rp->q.list, &cd->queue);
1035                spin_unlock(&queue_lock);
1036        }
1037        if (filp->f_mode & FMODE_WRITE)
1038                atomic_inc(&cd->writers);
1039        filp->private_data = rp;
1040        return 0;
1041}
1042
1043static int cache_release(struct inode *inode, struct file *filp,
1044                         struct cache_detail *cd)
1045{
1046        struct cache_reader *rp = filp->private_data;
1047
1048        if (rp) {
1049                spin_lock(&queue_lock);
1050                if (rp->offset) {
1051                        struct cache_queue *cq;
1052                        for (cq= &rp->q; &cq->list != &cd->queue;
1053                             cq = list_entry(cq->list.next, struct cache_queue, list))
1054                                if (!cq->reader) {
1055                                        container_of(cq, struct cache_request, q)
1056                                                ->readers--;
1057                                        break;
1058                                }
1059                        rp->offset = 0;
1060                }
1061                list_del(&rp->q.list);
1062                spin_unlock(&queue_lock);
1063
1064                filp->private_data = NULL;
1065                kfree(rp);
1066
1067        }
1068        if (filp->f_mode & FMODE_WRITE) {
1069                atomic_dec(&cd->writers);
1070                cd->last_close = seconds_since_boot();
1071        }
1072        module_put(cd->owner);
1073        return 0;
1074}
1075
1076
1077
1078static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch)
1079{
1080        struct cache_queue *cq, *tmp;
1081        struct cache_request *cr;
1082        struct list_head dequeued;
1083
1084        INIT_LIST_HEAD(&dequeued);
1085        spin_lock(&queue_lock);
1086        list_for_each_entry_safe(cq, tmp, &detail->queue, list)
1087                if (!cq->reader) {
1088                        cr = container_of(cq, struct cache_request, q);
1089                        if (cr->item != ch)
1090                                continue;
1091                        if (test_bit(CACHE_PENDING, &ch->flags))
1092                                /* Lost a race and it is pending again */
1093                                break;
1094                        if (cr->readers != 0)
1095                                continue;
1096                        list_move(&cr->q.list, &dequeued);
1097                }
1098        spin_unlock(&queue_lock);
1099        while (!list_empty(&dequeued)) {
1100                cr = list_entry(dequeued.next, struct cache_request, q.list);
1101                list_del(&cr->q.list);
1102                cache_put(cr->item, detail);
1103                kfree(cr->buf);
1104                kfree(cr);
1105        }
1106}
1107
1108/*
1109 * Support routines for text-based upcalls.
1110 * Fields are separated by spaces.
1111 * Fields are either mangled to quote space tab newline slosh with slosh
1112 * or a hexified with a leading \x
1113 * Record is terminated with newline.
1114 *
1115 */
1116
1117void qword_add(char **bpp, int *lp, char *str)
1118{
1119        char *bp = *bpp;
1120        int len = *lp;
1121        int ret;
1122
1123        if (len < 0) return;
1124
1125        ret = string_escape_str(str, bp, len, ESCAPE_OCTAL, "\\ \n\t");
1126        if (ret >= len) {
1127                bp += len;
1128                len = -1;
1129        } else {
1130                bp += ret;
1131                len -= ret;
1132                *bp++ = ' ';
1133                len--;
1134        }
1135        *bpp = bp;
1136        *lp = len;
1137}
1138EXPORT_SYMBOL_GPL(qword_add);
1139
1140void qword_addhex(char **bpp, int *lp, char *buf, int blen)
1141{
1142        char *bp = *bpp;
1143        int len = *lp;
1144
1145        if (len < 0) return;
1146
1147        if (len > 2) {
1148                *bp++ = '\\';
1149                *bp++ = 'x';
1150                len -= 2;
1151                while (blen && len >= 2) {
1152                        bp = hex_byte_pack(bp, *buf++);
1153                        len -= 2;
1154                        blen--;
1155                }
1156        }
1157        if (blen || len<1) len = -1;
1158        else {
1159                *bp++ = ' ';
1160                len--;
1161        }
1162        *bpp = bp;
1163        *lp = len;
1164}
1165EXPORT_SYMBOL_GPL(qword_addhex);
1166
1167static void warn_no_listener(struct cache_detail *detail)
1168{
1169        if (detail->last_warn != detail->last_close) {
1170                detail->last_warn = detail->last_close;
1171                if (detail->warn_no_listener)
1172                        detail->warn_no_listener(detail, detail->last_close != 0);
1173        }
1174}
1175
1176static bool cache_listeners_exist(struct cache_detail *detail)
1177{
1178        if (atomic_read(&detail->writers))
1179                return true;
1180        if (detail->last_close == 0)
1181                /* This cache was never opened */
1182                return false;
1183        if (detail->last_close < seconds_since_boot() - 30)
1184                /*
1185                 * We allow for the possibility that someone might
1186                 * restart a userspace daemon without restarting the
1187                 * server; but after 30 seconds, we give up.
1188                 */
1189                 return false;
1190        return true;
1191}
1192
1193/*
1194 * register an upcall request to user-space and queue it up for read() by the
1195 * upcall daemon.
1196 *
1197 * Each request is at most one page long.
1198 */
1199int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h)
1200{
1201
1202        char *buf;
1203        struct cache_request *crq;
1204        int ret = 0;
1205
1206        if (!detail->cache_request)
1207                return -EINVAL;
1208
1209        if (!cache_listeners_exist(detail)) {
1210                warn_no_listener(detail);
1211                return -EINVAL;
1212        }
1213        if (test_bit(CACHE_CLEANED, &h->flags))
1214                /* Too late to make an upcall */
1215                return -EAGAIN;
1216
1217        buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
1218        if (!buf)
1219                return -EAGAIN;
1220
1221        crq = kmalloc(sizeof (*crq), GFP_KERNEL);
1222        if (!crq) {
1223                kfree(buf);
1224                return -EAGAIN;
1225        }
1226
1227        crq->q.reader = 0;
1228        crq->buf = buf;
1229        crq->len = 0;
1230        crq->readers = 0;
1231        spin_lock(&queue_lock);
1232        if (test_bit(CACHE_PENDING, &h->flags)) {
1233                crq->item = cache_get(h);
1234                list_add_tail(&crq->q.list, &detail->queue);
1235        } else
1236                /* Lost a race, no longer PENDING, so don't enqueue */
1237                ret = -EAGAIN;
1238        spin_unlock(&queue_lock);
1239        wake_up(&queue_wait);
1240        if (ret == -EAGAIN) {
1241                kfree(buf);
1242                kfree(crq);
1243        }
1244        return ret;
1245}
1246EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall);
1247
1248/*
1249 * parse a message from user-space and pass it
1250 * to an appropriate cache
1251 * Messages are, like requests, separated into fields by
1252 * spaces and dequotes as \xHEXSTRING or embedded \nnn octal
1253 *
1254 * Message is
1255 *   reply cachename expiry key ... content....
1256 *
1257 * key and content are both parsed by cache
1258 */
1259
1260int qword_get(char **bpp, char *dest, int bufsize)
1261{
1262        /* return bytes copied, or -1 on error */
1263        char *bp = *bpp;
1264        int len = 0;
1265
1266        while (*bp == ' ') bp++;
1267
1268        if (bp[0] == '\\' && bp[1] == 'x') {
1269                /* HEX STRING */
1270                bp += 2;
1271                while (len < bufsize - 1) {
1272                        int h, l;
1273
1274                        h = hex_to_bin(bp[0]);
1275                        if (h < 0)
1276                                break;
1277
1278                        l = hex_to_bin(bp[1]);
1279                        if (l < 0)
1280                                break;
1281
1282                        *dest++ = (h << 4) | l;
1283                        bp += 2;
1284                        len++;
1285                }
1286        } else {
1287                /* text with \nnn octal quoting */
1288                while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) {
1289                        if (*bp == '\\' &&
1290                            isodigit(bp[1]) && (bp[1] <= '3') &&
1291                            isodigit(bp[2]) &&
1292                            isodigit(bp[3])) {
1293                                int byte = (*++bp -'0');
1294                                bp++;
1295                                byte = (byte << 3) | (*bp++ - '0');
1296                                byte = (byte << 3) | (*bp++ - '0');
1297                                *dest++ = byte;
1298                                len++;
1299                        } else {
1300                                *dest++ = *bp++;
1301                                len++;
1302                        }
1303                }
1304        }
1305
1306        if (*bp != ' ' && *bp != '\n' && *bp != '\0')
1307                return -1;
1308        while (*bp == ' ') bp++;
1309        *bpp = bp;
1310        *dest = '\0';
1311        return len;
1312}
1313EXPORT_SYMBOL_GPL(qword_get);
1314
1315
1316/*
1317 * support /proc/net/rpc/$CACHENAME/content
1318 * as a seqfile.
1319 * We call ->cache_show passing NULL for the item to
1320 * get a header, then pass each real item in the cache
1321 */
1322
1323static void *__cache_seq_start(struct seq_file *m, loff_t *pos)
1324{
1325        loff_t n = *pos;
1326        unsigned int hash, entry;
1327        struct cache_head *ch;
1328        struct cache_detail *cd = m->private;
1329
1330        if (!n--)
1331                return SEQ_START_TOKEN;
1332        hash = n >> 32;
1333        entry = n & ((1LL<<32) - 1);
1334
1335        hlist_for_each_entry_rcu(ch, &cd->hash_table[hash], cache_list)
1336                if (!entry--)
1337                        return ch;
1338        n &= ~((1LL<<32) - 1);
1339        do {
1340                hash++;
1341                n += 1LL<<32;
1342        } while(hash < cd->hash_size &&
1343                hlist_empty(&cd->hash_table[hash]));
1344        if (hash >= cd->hash_size)
1345                return NULL;
1346        *pos = n+1;
1347        return hlist_entry_safe(rcu_dereference_raw(
1348                                hlist_first_rcu(&cd->hash_table[hash])),
1349                                struct cache_head, cache_list);
1350}
1351
1352static void *cache_seq_next(struct seq_file *m, void *p, loff_t *pos)
1353{
1354        struct cache_head *ch = p;
1355        int hash = (*pos >> 32);
1356        struct cache_detail *cd = m->private;
1357
1358        if (p == SEQ_START_TOKEN)
1359                hash = 0;
1360        else if (ch->cache_list.next == NULL) {
1361                hash++;
1362                *pos += 1LL<<32;
1363        } else {
1364                ++*pos;
1365                return hlist_entry_safe(rcu_dereference_raw(
1366                                        hlist_next_rcu(&ch->cache_list)),
1367                                        struct cache_head, cache_list);
1368        }
1369        *pos &= ~((1LL<<32) - 1);
1370        while (hash < cd->hash_size &&
1371               hlist_empty(&cd->hash_table[hash])) {
1372                hash++;
1373                *pos += 1LL<<32;
1374        }
1375        if (hash >= cd->hash_size)
1376                return NULL;
1377        ++*pos;
1378        return hlist_entry_safe(rcu_dereference_raw(
1379                                hlist_first_rcu(&cd->hash_table[hash])),
1380                                struct cache_head, cache_list);
1381}
1382
1383void *cache_seq_start_rcu(struct seq_file *m, loff_t *pos)
1384        __acquires(RCU)
1385{
1386        rcu_read_lock();
1387        return __cache_seq_start(m, pos);
1388}
1389EXPORT_SYMBOL_GPL(cache_seq_start_rcu);
1390
1391void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos)
1392{
1393        return cache_seq_next(file, p, pos);
1394}
1395EXPORT_SYMBOL_GPL(cache_seq_next_rcu);
1396
1397void cache_seq_stop_rcu(struct seq_file *m, void *p)
1398        __releases(RCU)
1399{
1400        rcu_read_unlock();
1401}
1402EXPORT_SYMBOL_GPL(cache_seq_stop_rcu);
1403
1404static int c_show(struct seq_file *m, void *p)
1405{
1406        struct cache_head *cp = p;
1407        struct cache_detail *cd = m->private;
1408
1409        if (p == SEQ_START_TOKEN)
1410                return cd->cache_show(m, cd, NULL);
1411
1412        ifdebug(CACHE)
1413                seq_printf(m, "# expiry=%ld refcnt=%d flags=%lx\n",
1414                           convert_to_wallclock(cp->expiry_time),
1415                           kref_read(&cp->ref), cp->flags);
1416        cache_get(cp);
1417        if (cache_check(cd, cp, NULL))
1418                /* cache_check does a cache_put on failure */
1419                seq_printf(m, "# ");
1420        else {
1421                if (cache_is_expired(cd, cp))
1422                        seq_printf(m, "# ");
1423                cache_put(cp, cd);
1424        }
1425
1426        return cd->cache_show(m, cd, cp);
1427}
1428
1429static const struct seq_operations cache_content_op = {
1430        .start  = cache_seq_start_rcu,
1431        .next   = cache_seq_next_rcu,
1432        .stop   = cache_seq_stop_rcu,
1433        .show   = c_show,
1434};
1435
1436static int content_open(struct inode *inode, struct file *file,
1437                        struct cache_detail *cd)
1438{
1439        struct seq_file *seq;
1440        int err;
1441
1442        if (!cd || !try_module_get(cd->owner))
1443                return -EACCES;
1444
1445        err = seq_open(file, &cache_content_op);
1446        if (err) {
1447                module_put(cd->owner);
1448                return err;
1449        }
1450
1451        seq = file->private_data;
1452        seq->private = cd;
1453        return 0;
1454}
1455
1456static int content_release(struct inode *inode, struct file *file,
1457                struct cache_detail *cd)
1458{
1459        int ret = seq_release(inode, file);
1460        module_put(cd->owner);
1461        return ret;
1462}
1463
1464static int open_flush(struct inode *inode, struct file *file,
1465                        struct cache_detail *cd)
1466{
1467        if (!cd || !try_module_get(cd->owner))
1468                return -EACCES;
1469        return nonseekable_open(inode, file);
1470}
1471
1472static int release_flush(struct inode *inode, struct file *file,
1473                        struct cache_detail *cd)
1474{
1475        module_put(cd->owner);
1476        return 0;
1477}
1478
1479static ssize_t read_flush(struct file *file, char __user *buf,
1480                          size_t count, loff_t *ppos,
1481                          struct cache_detail *cd)
1482{
1483        char tbuf[22];
1484        size_t len;
1485
1486        len = snprintf(tbuf, sizeof(tbuf), "%lu\n",
1487                        convert_to_wallclock(cd->flush_time));
1488        return simple_read_from_buffer(buf, count, ppos, tbuf, len);
1489}
1490
1491static ssize_t write_flush(struct file *file, const char __user *buf,
1492                           size_t count, loff_t *ppos,
1493                           struct cache_detail *cd)
1494{
1495        char tbuf[20];
1496        char *ep;
1497        time_t now;
1498
1499        if (*ppos || count > sizeof(tbuf)-1)
1500                return -EINVAL;
1501        if (copy_from_user(tbuf, buf, count))
1502                return -EFAULT;
1503        tbuf[count] = 0;
1504        simple_strtoul(tbuf, &ep, 0);
1505        if (*ep && *ep != '\n')
1506                return -EINVAL;
1507        /* Note that while we check that 'buf' holds a valid number,
1508         * we always ignore the value and just flush everything.
1509         * Making use of the number leads to races.
1510         */
1511
1512        now = seconds_since_boot();
1513        /* Always flush everything, so behave like cache_purge()
1514         * Do this by advancing flush_time to the current time,
1515         * or by one second if it has already reached the current time.
1516         * Newly added cache entries will always have ->last_refresh greater
1517         * that ->flush_time, so they don't get flushed prematurely.
1518         */
1519
1520        if (cd->flush_time >= now)
1521                now = cd->flush_time + 1;
1522
1523        cd->flush_time = now;
1524        cd->nextcheck = now;
1525        cache_flush();
1526
1527        if (cd->flush)
1528                cd->flush();
1529
1530        *ppos += count;
1531        return count;
1532}
1533
1534static ssize_t cache_read_procfs(struct file *filp, char __user *buf,
1535                                 size_t count, loff_t *ppos)
1536{
1537        struct cache_detail *cd = PDE_DATA(file_inode(filp));
1538
1539        return cache_read(filp, buf, count, ppos, cd);
1540}
1541
1542static ssize_t cache_write_procfs(struct file *filp, const char __user *buf,
1543                                  size_t count, loff_t *ppos)
1544{
1545        struct cache_detail *cd = PDE_DATA(file_inode(filp));
1546
1547        return cache_write(filp, buf, count, ppos, cd);
1548}
1549
1550static __poll_t cache_poll_procfs(struct file *filp, poll_table *wait)
1551{
1552        struct cache_detail *cd = PDE_DATA(file_inode(filp));
1553
1554        return cache_poll(filp, wait, cd);
1555}
1556
1557static long cache_ioctl_procfs(struct file *filp,
1558                               unsigned int cmd, unsigned long arg)
1559{
1560        struct inode *inode = file_inode(filp);
1561        struct cache_detail *cd = PDE_DATA(inode);
1562
1563        return cache_ioctl(inode, filp, cmd, arg, cd);
1564}
1565
1566static int cache_open_procfs(struct inode *inode, struct file *filp)
1567{
1568        struct cache_detail *cd = PDE_DATA(inode);
1569
1570        return cache_open(inode, filp, cd);
1571}
1572
1573static int cache_release_procfs(struct inode *inode, struct file *filp)
1574{
1575        struct cache_detail *cd = PDE_DATA(inode);
1576
1577        return cache_release(inode, filp, cd);
1578}
1579
1580static const struct file_operations cache_file_operations_procfs = {
1581        .owner          = THIS_MODULE,
1582        .llseek         = no_llseek,
1583        .read           = cache_read_procfs,
1584        .write          = cache_write_procfs,
1585        .poll           = cache_poll_procfs,
1586        .unlocked_ioctl = cache_ioctl_procfs, /* for FIONREAD */
1587        .open           = cache_open_procfs,
1588        .release        = cache_release_procfs,
1589};
1590
1591static int content_open_procfs(struct inode *inode, struct file *filp)
1592{
1593        struct cache_detail *cd = PDE_DATA(inode);
1594
1595        return content_open(inode, filp, cd);
1596}
1597
1598static int content_release_procfs(struct inode *inode, struct file *filp)
1599{
1600        struct cache_detail *cd = PDE_DATA(inode);
1601
1602        return content_release(inode, filp, cd);
1603}
1604
1605static const struct file_operations content_file_operations_procfs = {
1606        .open           = content_open_procfs,
1607        .read           = seq_read,
1608        .llseek         = seq_lseek,
1609        .release        = content_release_procfs,
1610};
1611
1612static int open_flush_procfs(struct inode *inode, struct file *filp)
1613{
1614        struct cache_detail *cd = PDE_DATA(inode);
1615
1616        return open_flush(inode, filp, cd);
1617}
1618
1619static int release_flush_procfs(struct inode *inode, struct file *filp)
1620{
1621        struct cache_detail *cd = PDE_DATA(inode);
1622
1623        return release_flush(inode, filp, cd);
1624}
1625
1626static ssize_t read_flush_procfs(struct file *filp, char __user *buf,
1627                            size_t count, loff_t *ppos)
1628{
1629        struct cache_detail *cd = PDE_DATA(file_inode(filp));
1630
1631        return read_flush(filp, buf, count, ppos, cd);
1632}
1633
1634static ssize_t write_flush_procfs(struct file *filp,
1635                                  const char __user *buf,
1636                                  size_t count, loff_t *ppos)
1637{
1638        struct cache_detail *cd = PDE_DATA(file_inode(filp));
1639
1640        return write_flush(filp, buf, count, ppos, cd);
1641}
1642
1643static const struct file_operations cache_flush_operations_procfs = {
1644        .open           = open_flush_procfs,
1645        .read           = read_flush_procfs,
1646        .write          = write_flush_procfs,
1647        .release        = release_flush_procfs,
1648        .llseek         = no_llseek,
1649};
1650
1651static void remove_cache_proc_entries(struct cache_detail *cd)
1652{
1653        if (cd->procfs) {
1654                proc_remove(cd->procfs);
1655                cd->procfs = NULL;
1656        }
1657}
1658
1659#ifdef CONFIG_PROC_FS
1660static int create_cache_proc_entries(struct cache_detail *cd, struct net *net)
1661{
1662        struct proc_dir_entry *p;
1663        struct sunrpc_net *sn;
1664
1665        sn = net_generic(net, sunrpc_net_id);
1666        cd->procfs = proc_mkdir(cd->name, sn->proc_net_rpc);
1667        if (cd->procfs == NULL)
1668                goto out_nomem;
1669
1670        p = proc_create_data("flush", S_IFREG | 0600,
1671                             cd->procfs, &cache_flush_operations_procfs, cd);
1672        if (p == NULL)
1673                goto out_nomem;
1674
1675        if (cd->cache_request || cd->cache_parse) {
1676                p = proc_create_data("channel", S_IFREG | 0600, cd->procfs,
1677                                     &cache_file_operations_procfs, cd);
1678                if (p == NULL)
1679                        goto out_nomem;
1680        }
1681        if (cd->cache_show) {
1682                p = proc_create_data("content", S_IFREG | 0400, cd->procfs,
1683                                     &content_file_operations_procfs, cd);
1684                if (p == NULL)
1685                        goto out_nomem;
1686        }
1687        return 0;
1688out_nomem:
1689        remove_cache_proc_entries(cd);
1690        return -ENOMEM;
1691}
1692#else /* CONFIG_PROC_FS */
1693static int create_cache_proc_entries(struct cache_detail *cd, struct net *net)
1694{
1695        return 0;
1696}
1697#endif
1698
1699void __init cache_initialize(void)
1700{
1701        INIT_DEFERRABLE_WORK(&cache_cleaner, do_cache_clean);
1702}
1703
1704int cache_register_net(struct cache_detail *cd, struct net *net)
1705{
1706        int ret;
1707
1708        sunrpc_init_cache_detail(cd);
1709        ret = create_cache_proc_entries(cd, net);
1710        if (ret)
1711                sunrpc_destroy_cache_detail(cd);
1712        return ret;
1713}
1714EXPORT_SYMBOL_GPL(cache_register_net);
1715
1716void cache_unregister_net(struct cache_detail *cd, struct net *net)
1717{
1718        remove_cache_proc_entries(cd);
1719        sunrpc_destroy_cache_detail(cd);
1720}
1721EXPORT_SYMBOL_GPL(cache_unregister_net);
1722
1723struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net)
1724{
1725        struct cache_detail *cd;
1726        int i;
1727
1728        cd = kmemdup(tmpl, sizeof(struct cache_detail), GFP_KERNEL);
1729        if (cd == NULL)
1730                return ERR_PTR(-ENOMEM);
1731
1732        cd->hash_table = kcalloc(cd->hash_size, sizeof(struct hlist_head),
1733                                 GFP_KERNEL);
1734        if (cd->hash_table == NULL) {
1735                kfree(cd);
1736                return ERR_PTR(-ENOMEM);
1737        }
1738
1739        for (i = 0; i < cd->hash_size; i++)
1740                INIT_HLIST_HEAD(&cd->hash_table[i]);
1741        cd->net = net;
1742        return cd;
1743}
1744EXPORT_SYMBOL_GPL(cache_create_net);
1745
1746void cache_destroy_net(struct cache_detail *cd, struct net *net)
1747{
1748        kfree(cd->hash_table);
1749        kfree(cd);
1750}
1751EXPORT_SYMBOL_GPL(cache_destroy_net);
1752
1753static ssize_t cache_read_pipefs(struct file *filp, char __user *buf,
1754                                 size_t count, loff_t *ppos)
1755{
1756        struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1757
1758        return cache_read(filp, buf, count, ppos, cd);
1759}
1760
1761static ssize_t cache_write_pipefs(struct file *filp, const char __user *buf,
1762                                  size_t count, loff_t *ppos)
1763{
1764        struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1765
1766        return cache_write(filp, buf, count, ppos, cd);
1767}
1768
1769static __poll_t cache_poll_pipefs(struct file *filp, poll_table *wait)
1770{
1771        struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1772
1773        return cache_poll(filp, wait, cd);
1774}
1775
1776static long cache_ioctl_pipefs(struct file *filp,
1777                              unsigned int cmd, unsigned long arg)
1778{
1779        struct inode *inode = file_inode(filp);
1780        struct cache_detail *cd = RPC_I(inode)->private;
1781
1782        return cache_ioctl(inode, filp, cmd, arg, cd);
1783}
1784
1785static int cache_open_pipefs(struct inode *inode, struct file *filp)
1786{
1787        struct cache_detail *cd = RPC_I(inode)->private;
1788
1789        return cache_open(inode, filp, cd);
1790}
1791
1792static int cache_release_pipefs(struct inode *inode, struct file *filp)
1793{
1794        struct cache_detail *cd = RPC_I(inode)->private;
1795
1796        return cache_release(inode, filp, cd);
1797}
1798
1799const struct file_operations cache_file_operations_pipefs = {
1800        .owner          = THIS_MODULE,
1801        .llseek         = no_llseek,
1802        .read           = cache_read_pipefs,
1803        .write          = cache_write_pipefs,
1804        .poll           = cache_poll_pipefs,
1805        .unlocked_ioctl = cache_ioctl_pipefs, /* for FIONREAD */
1806        .open           = cache_open_pipefs,
1807        .release        = cache_release_pipefs,
1808};
1809
1810static int content_open_pipefs(struct inode *inode, struct file *filp)
1811{
1812        struct cache_detail *cd = RPC_I(inode)->private;
1813
1814        return content_open(inode, filp, cd);
1815}
1816
1817static int content_release_pipefs(struct inode *inode, struct file *filp)
1818{
1819        struct cache_detail *cd = RPC_I(inode)->private;
1820
1821        return content_release(inode, filp, cd);
1822}
1823
1824const struct file_operations content_file_operations_pipefs = {
1825        .open           = content_open_pipefs,
1826        .read           = seq_read,
1827        .llseek         = seq_lseek,
1828        .release        = content_release_pipefs,
1829};
1830
1831static int open_flush_pipefs(struct inode *inode, struct file *filp)
1832{
1833        struct cache_detail *cd = RPC_I(inode)->private;
1834
1835        return open_flush(inode, filp, cd);
1836}
1837
1838static int release_flush_pipefs(struct inode *inode, struct file *filp)
1839{
1840        struct cache_detail *cd = RPC_I(inode)->private;
1841
1842        return release_flush(inode, filp, cd);
1843}
1844
1845static ssize_t read_flush_pipefs(struct file *filp, char __user *buf,
1846                            size_t count, loff_t *ppos)
1847{
1848        struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1849
1850        return read_flush(filp, buf, count, ppos, cd);
1851}
1852
1853static ssize_t write_flush_pipefs(struct file *filp,
1854                                  const char __user *buf,
1855                                  size_t count, loff_t *ppos)
1856{
1857        struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1858
1859        return write_flush(filp, buf, count, ppos, cd);
1860}
1861
1862const struct file_operations cache_flush_operations_pipefs = {
1863        .open           = open_flush_pipefs,
1864        .read           = read_flush_pipefs,
1865        .write          = write_flush_pipefs,
1866        .release        = release_flush_pipefs,
1867        .llseek         = no_llseek,
1868};
1869
1870int sunrpc_cache_register_pipefs(struct dentry *parent,
1871                                 const char *name, umode_t umode,
1872                                 struct cache_detail *cd)
1873{
1874        struct dentry *dir = rpc_create_cache_dir(parent, name, umode, cd);
1875        if (IS_ERR(dir))
1876                return PTR_ERR(dir);
1877        cd->pipefs = dir;
1878        return 0;
1879}
1880EXPORT_SYMBOL_GPL(sunrpc_cache_register_pipefs);
1881
1882void sunrpc_cache_unregister_pipefs(struct cache_detail *cd)
1883{
1884        if (cd->pipefs) {
1885                rpc_remove_cache_dir(cd->pipefs);
1886                cd->pipefs = NULL;
1887        }
1888}
1889EXPORT_SYMBOL_GPL(sunrpc_cache_unregister_pipefs);
1890
1891void sunrpc_cache_unhash(struct cache_detail *cd, struct cache_head *h)
1892{
1893        spin_lock(&cd->hash_lock);
1894        if (!hlist_unhashed(&h->cache_list)){
1895                hlist_del_init_rcu(&h->cache_list);
1896                cd->entries--;
1897                spin_unlock(&cd->hash_lock);
1898                cache_put(h, cd);
1899        } else
1900                spin_unlock(&cd->hash_lock);
1901}
1902EXPORT_SYMBOL_GPL(sunrpc_cache_unhash);
1903