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 <trace/events/sunrpc.h>
  36
  37#include "netns.h"
  38#include "fail.h"
  39
  40#define	 RPCDBG_FACILITY RPCDBG_CACHE
  41
  42static bool cache_defer_req(struct cache_req *req, struct cache_head *item);
  43static void cache_revisit_request(struct cache_head *item);
  44
  45static void cache_init(struct cache_head *h, struct cache_detail *detail)
  46{
  47	time64_t now = seconds_since_boot();
  48	INIT_HLIST_NODE(&h->cache_list);
  49	h->flags = 0;
  50	kref_init(&h->ref);
  51	h->expiry_time = now + CACHE_NEW_EXPIRY;
  52	if (now <= detail->flush_time)
  53		/* ensure it isn't already expired */
  54		now = detail->flush_time + 1;
  55	h->last_refresh = now;
  56}
  57
  58static void cache_fresh_unlocked(struct cache_head *head,
  59				struct cache_detail *detail);
  60
  61static struct cache_head *sunrpc_cache_find_rcu(struct cache_detail *detail,
  62						struct cache_head *key,
  63						int hash)
  64{
  65	struct hlist_head *head = &detail->hash_table[hash];
  66	struct cache_head *tmp;
  67
  68	rcu_read_lock();
  69	hlist_for_each_entry_rcu(tmp, head, cache_list) {
  70		if (!detail->match(tmp, key))
  71			continue;
  72		if (test_bit(CACHE_VALID, &tmp->flags) &&
  73		    cache_is_expired(detail, tmp))
  74			continue;
  75		tmp = cache_get_rcu(tmp);
  76		rcu_read_unlock();
  77		return tmp;
  78	}
  79	rcu_read_unlock();
  80	return NULL;
  81}
  82
  83static void sunrpc_begin_cache_remove_entry(struct cache_head *ch,
  84					    struct cache_detail *cd)
  85{
  86	/* Must be called under cd->hash_lock */
  87	hlist_del_init_rcu(&ch->cache_list);
  88	set_bit(CACHE_CLEANED, &ch->flags);
  89	cd->entries --;
  90}
  91
  92static void sunrpc_end_cache_remove_entry(struct cache_head *ch,
  93					  struct cache_detail *cd)
  94{
  95	cache_fresh_unlocked(ch, cd);
  96	cache_put(ch, cd);
  97}
  98
  99static struct cache_head *sunrpc_cache_add_entry(struct cache_detail *detail,
 100						 struct cache_head *key,
 101						 int hash)
 102{
 103	struct cache_head *new, *tmp, *freeme = NULL;
 104	struct hlist_head *head = &detail->hash_table[hash];
 105
 106	new = detail->alloc();
 107	if (!new)
 108		return NULL;
 109	/* must fully initialise 'new', else
 110	 * we might get lose if we need to
 111	 * cache_put it soon.
 112	 */
 113	cache_init(new, detail);
 114	detail->init(new, key);
 115
 116	spin_lock(&detail->hash_lock);
 117
 118	/* check if entry appeared while we slept */
 119	hlist_for_each_entry_rcu(tmp, head, cache_list,
 120				 lockdep_is_held(&detail->hash_lock)) {
 121		if (!detail->match(tmp, key))
 122			continue;
 123		if (test_bit(CACHE_VALID, &tmp->flags) &&
 124		    cache_is_expired(detail, tmp)) {
 125			sunrpc_begin_cache_remove_entry(tmp, detail);
 126			trace_cache_entry_expired(detail, tmp);
 127			freeme = tmp;
 128			break;
 129		}
 130		cache_get(tmp);
 131		spin_unlock(&detail->hash_lock);
 132		cache_put(new, detail);
 133		return tmp;
 134	}
 135
 136	hlist_add_head_rcu(&new->cache_list, head);
 137	detail->entries++;
 138	cache_get(new);
 139	spin_unlock(&detail->hash_lock);
 140
 141	if (freeme)
 142		sunrpc_end_cache_remove_entry(freeme, detail);
 143	return new;
 144}
 145
 146struct cache_head *sunrpc_cache_lookup_rcu(struct cache_detail *detail,
 147					   struct cache_head *key, int hash)
 148{
 149	struct cache_head *ret;
 150
 151	ret = sunrpc_cache_find_rcu(detail, key, hash);
 152	if (ret)
 153		return ret;
 154	/* Didn't find anything, insert an empty entry */
 155	return sunrpc_cache_add_entry(detail, key, hash);
 156}
 157EXPORT_SYMBOL_GPL(sunrpc_cache_lookup_rcu);
 158
 159static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch);
 160
 161static void cache_fresh_locked(struct cache_head *head, time64_t expiry,
 162			       struct cache_detail *detail)
 163{
 164	time64_t now = seconds_since_boot();
 165	if (now <= detail->flush_time)
 166		/* ensure it isn't immediately treated as expired */
 167		now = detail->flush_time + 1;
 168	head->expiry_time = expiry;
 169	head->last_refresh = now;
 170	smp_wmb(); /* paired with smp_rmb() in cache_is_valid() */
 171	set_bit(CACHE_VALID, &head->flags);
 172}
 173
 174static void cache_fresh_unlocked(struct cache_head *head,
 175				 struct cache_detail *detail)
 176{
 177	if (test_and_clear_bit(CACHE_PENDING, &head->flags)) {
 178		cache_revisit_request(head);
 179		cache_dequeue(detail, head);
 180	}
 181}
 182
 183static void cache_make_negative(struct cache_detail *detail,
 184				struct cache_head *h)
 185{
 186	set_bit(CACHE_NEGATIVE, &h->flags);
 187	trace_cache_entry_make_negative(detail, h);
 188}
 189
 190static void cache_entry_update(struct cache_detail *detail,
 191			       struct cache_head *h,
 192			       struct cache_head *new)
 193{
 194	if (!test_bit(CACHE_NEGATIVE, &new->flags)) {
 195		detail->update(h, new);
 196		trace_cache_entry_update(detail, h);
 197	} else {
 198		cache_make_negative(detail, h);
 199	}
 200}
 201
 202struct cache_head *sunrpc_cache_update(struct cache_detail *detail,
 203				       struct cache_head *new, struct cache_head *old, int hash)
 204{
 205	/* The 'old' entry is to be replaced by 'new'.
 206	 * If 'old' is not VALID, we update it directly,
 207	 * otherwise we need to replace it
 208	 */
 209	struct cache_head *tmp;
 210
 211	if (!test_bit(CACHE_VALID, &old->flags)) {
 212		spin_lock(&detail->hash_lock);
 213		if (!test_bit(CACHE_VALID, &old->flags)) {
 214			cache_entry_update(detail, old, new);
 215			cache_fresh_locked(old, new->expiry_time, detail);
 216			spin_unlock(&detail->hash_lock);
 217			cache_fresh_unlocked(old, detail);
 218			return old;
 219		}
 220		spin_unlock(&detail->hash_lock);
 221	}
 222	/* We need to insert a new entry */
 223	tmp = detail->alloc();
 224	if (!tmp) {
 225		cache_put(old, detail);
 226		return NULL;
 227	}
 228	cache_init(tmp, detail);
 229	detail->init(tmp, old);
 230
 231	spin_lock(&detail->hash_lock);
 232	cache_entry_update(detail, tmp, new);
 233	hlist_add_head(&tmp->cache_list, &detail->hash_table[hash]);
 234	detail->entries++;
 235	cache_get(tmp);
 236	cache_fresh_locked(tmp, new->expiry_time, detail);
 237	cache_fresh_locked(old, 0, detail);
 238	spin_unlock(&detail->hash_lock);
 239	cache_fresh_unlocked(tmp, detail);
 240	cache_fresh_unlocked(old, detail);
 241	cache_put(old, detail);
 242	return tmp;
 243}
 244EXPORT_SYMBOL_GPL(sunrpc_cache_update);
 245
 246static inline int cache_is_valid(struct cache_head *h)
 247{
 248	if (!test_bit(CACHE_VALID, &h->flags))
 249		return -EAGAIN;
 250	else {
 251		/* entry is valid */
 252		if (test_bit(CACHE_NEGATIVE, &h->flags))
 253			return -ENOENT;
 254		else {
 255			/*
 256			 * In combination with write barrier in
 257			 * sunrpc_cache_update, ensures that anyone
 258			 * using the cache entry after this sees the
 259			 * updated contents:
 260			 */
 261			smp_rmb();
 262			return 0;
 263		}
 264	}
 265}
 266
 267static int try_to_negate_entry(struct cache_detail *detail, struct cache_head *h)
 268{
 269	int rv;
 270
 271	spin_lock(&detail->hash_lock);
 272	rv = cache_is_valid(h);
 273	if (rv == -EAGAIN) {
 274		cache_make_negative(detail, h);
 275		cache_fresh_locked(h, seconds_since_boot()+CACHE_NEW_EXPIRY,
 276				   detail);
 277		rv = -ENOENT;
 278	}
 279	spin_unlock(&detail->hash_lock);
 280	cache_fresh_unlocked(h, detail);
 281	return rv;
 282}
 283
 284/*
 285 * This is the generic cache management routine for all
 286 * the authentication caches.
 287 * It checks the currency of a cache item and will (later)
 288 * initiate an upcall to fill it if needed.
 289 *
 290 *
 291 * Returns 0 if the cache_head can be used, or cache_puts it and returns
 292 * -EAGAIN if upcall is pending and request has been queued
 293 * -ETIMEDOUT if upcall failed or request could not be queue or
 294 *           upcall completed but item is still invalid (implying that
 295 *           the cache item has been replaced with a newer one).
 296 * -ENOENT if cache entry was negative
 297 */
 298int cache_check(struct cache_detail *detail,
 299		    struct cache_head *h, struct cache_req *rqstp)
 300{
 301	int rv;
 302	time64_t refresh_age, age;
 303
 304	/* First decide return status as best we can */
 305	rv = cache_is_valid(h);
 306
 307	/* now see if we want to start an upcall */
 308	refresh_age = (h->expiry_time - h->last_refresh);
 309	age = seconds_since_boot() - h->last_refresh;
 310
 311	if (rqstp == NULL) {
 312		if (rv == -EAGAIN)
 313			rv = -ENOENT;
 314	} else if (rv == -EAGAIN ||
 315		   (h->expiry_time != 0 && age > refresh_age/2)) {
 316		dprintk("RPC:       Want update, refage=%lld, age=%lld\n",
 317				refresh_age, age);
 318		switch (detail->cache_upcall(detail, h)) {
 319		case -EINVAL:
 320			rv = try_to_negate_entry(detail, h);
 321			break;
 322		case -EAGAIN:
 323			cache_fresh_unlocked(h, detail);
 324			break;
 325		}
 326	}
 327
 328	if (rv == -EAGAIN) {
 329		if (!cache_defer_req(rqstp, h)) {
 330			/*
 331			 * Request was not deferred; handle it as best
 332			 * we can ourselves:
 333			 */
 334			rv = cache_is_valid(h);
 335			if (rv == -EAGAIN)
 336				rv = -ETIMEDOUT;
 337		}
 338	}
 339	if (rv)
 340		cache_put(h, detail);
 341	return rv;
 342}
 343EXPORT_SYMBOL_GPL(cache_check);
 344
 345/*
 346 * caches need to be periodically cleaned.
 347 * For this we maintain a list of cache_detail and
 348 * a current pointer into that list and into the table
 349 * for that entry.
 350 *
 351 * Each time cache_clean is called it finds the next non-empty entry
 352 * in the current table and walks the list in that entry
 353 * looking for entries that can be removed.
 354 *
 355 * An entry gets removed if:
 356 * - The expiry is before current time
 357 * - The last_refresh time is before the flush_time for that cache
 358 *
 359 * later we might drop old entries with non-NEVER expiry if that table
 360 * is getting 'full' for some definition of 'full'
 361 *
 362 * The question of "how often to scan a table" is an interesting one
 363 * and is answered in part by the use of the "nextcheck" field in the
 364 * cache_detail.
 365 * When a scan of a table begins, the nextcheck field is set to a time
 366 * that is well into the future.
 367 * While scanning, if an expiry time is found that is earlier than the
 368 * current nextcheck time, nextcheck is set to that expiry time.
 369 * If the flush_time is ever set to a time earlier than the nextcheck
 370 * time, the nextcheck time is then set to that flush_time.
 371 *
 372 * A table is then only scanned if the current time is at least
 373 * the nextcheck time.
 374 *
 375 */
 376
 377static LIST_HEAD(cache_list);
 378static DEFINE_SPINLOCK(cache_list_lock);
 379static struct cache_detail *current_detail;
 380static int current_index;
 381
 382static void do_cache_clean(struct work_struct *work);
 383static struct delayed_work cache_cleaner;
 384
 385void sunrpc_init_cache_detail(struct cache_detail *cd)
 386{
 387	spin_lock_init(&cd->hash_lock);
 388	INIT_LIST_HEAD(&cd->queue);
 389	spin_lock(&cache_list_lock);
 390	cd->nextcheck = 0;
 391	cd->entries = 0;
 392	atomic_set(&cd->writers, 0);
 393	cd->last_close = 0;
 394	cd->last_warn = -1;
 395	list_add(&cd->others, &cache_list);
 396	spin_unlock(&cache_list_lock);
 397
 398	/* start the cleaning process */
 399	queue_delayed_work(system_power_efficient_wq, &cache_cleaner, 0);
 400}
 401EXPORT_SYMBOL_GPL(sunrpc_init_cache_detail);
 402
 403void sunrpc_destroy_cache_detail(struct cache_detail *cd)
 404{
 405	cache_purge(cd);
 406	spin_lock(&cache_list_lock);
 407	spin_lock(&cd->hash_lock);
 408	if (current_detail == cd)
 409		current_detail = NULL;
 410	list_del_init(&cd->others);
 411	spin_unlock(&cd->hash_lock);
 412	spin_unlock(&cache_list_lock);
 413	if (list_empty(&cache_list)) {
 414		/* module must be being unloaded so its safe to kill the worker */
 415		cancel_delayed_work_sync(&cache_cleaner);
 416	}
 417}
 418EXPORT_SYMBOL_GPL(sunrpc_destroy_cache_detail);
 419
 420/* clean cache tries to find something to clean
 421 * and cleans it.
 422 * It returns 1 if it cleaned something,
 423 *            0 if it didn't find anything this time
 424 *           -1 if it fell off the end of the list.
 425 */
 426static int cache_clean(void)
 427{
 428	int rv = 0;
 429	struct list_head *next;
 430
 431	spin_lock(&cache_list_lock);
 432
 433	/* find a suitable table if we don't already have one */
 434	while (current_detail == NULL ||
 435	    current_index >= current_detail->hash_size) {
 436		if (current_detail)
 437			next = current_detail->others.next;
 438		else
 439			next = cache_list.next;
 440		if (next == &cache_list) {
 441			current_detail = NULL;
 442			spin_unlock(&cache_list_lock);
 443			return -1;
 444		}
 445		current_detail = list_entry(next, struct cache_detail, others);
 446		if (current_detail->nextcheck > seconds_since_boot())
 447			current_index = current_detail->hash_size;
 448		else {
 449			current_index = 0;
 450			current_detail->nextcheck = seconds_since_boot()+30*60;
 451		}
 452	}
 453
 454	/* find a non-empty bucket in the table */
 455	while (current_detail &&
 456	       current_index < current_detail->hash_size &&
 457	       hlist_empty(&current_detail->hash_table[current_index]))
 458		current_index++;
 459
 460	/* find a cleanable entry in the bucket and clean it, or set to next bucket */
 461
 462	if (current_detail && current_index < current_detail->hash_size) {
 463		struct cache_head *ch = NULL;
 464		struct cache_detail *d;
 465		struct hlist_head *head;
 466		struct hlist_node *tmp;
 467
 468		spin_lock(&current_detail->hash_lock);
 469
 470		/* Ok, now to clean this strand */
 471
 472		head = &current_detail->hash_table[current_index];
 473		hlist_for_each_entry_safe(ch, tmp, head, cache_list) {
 474			if (current_detail->nextcheck > ch->expiry_time)
 475				current_detail->nextcheck = ch->expiry_time+1;
 476			if (!cache_is_expired(current_detail, ch))
 477				continue;
 478
 479			sunrpc_begin_cache_remove_entry(ch, current_detail);
 480			trace_cache_entry_expired(current_detail, ch);
 481			rv = 1;
 482			break;
 483		}
 484
 485		spin_unlock(&current_detail->hash_lock);
 486		d = current_detail;
 487		if (!ch)
 488			current_index ++;
 489		spin_unlock(&cache_list_lock);
 490		if (ch)
 491			sunrpc_end_cache_remove_entry(ch, d);
 492	} else
 493		spin_unlock(&cache_list_lock);
 494
 495	return rv;
 496}
 497
 498/*
 499 * We want to regularly clean the cache, so we need to schedule some work ...
 500 */
 501static void do_cache_clean(struct work_struct *work)
 502{
 503	int delay;
 504
 505	if (list_empty(&cache_list))
 506		return;
 507
 508	if (cache_clean() == -1)
 509		delay = round_jiffies_relative(30*HZ);
 510	else
 511		delay = 5;
 512
 513	queue_delayed_work(system_power_efficient_wq, &cache_cleaner, delay);
 
 
 
 
 
 514}
 515
 516
 517/*
 518 * Clean all caches promptly.  This just calls cache_clean
 519 * repeatedly until we are sure that every cache has had a chance to
 520 * be fully cleaned
 521 */
 522void cache_flush(void)
 523{
 524	while (cache_clean() != -1)
 525		cond_resched();
 526	while (cache_clean() != -1)
 527		cond_resched();
 528}
 529EXPORT_SYMBOL_GPL(cache_flush);
 530
 531void cache_purge(struct cache_detail *detail)
 532{
 533	struct cache_head *ch = NULL;
 534	struct hlist_head *head = NULL;
 535	int i = 0;
 536
 537	spin_lock(&detail->hash_lock);
 538	if (!detail->entries) {
 539		spin_unlock(&detail->hash_lock);
 540		return;
 541	}
 542
 543	dprintk("RPC: %d entries in %s cache\n", detail->entries, detail->name);
 544	for (i = 0; i < detail->hash_size; i++) {
 545		head = &detail->hash_table[i];
 546		while (!hlist_empty(head)) {
 547			ch = hlist_entry(head->first, struct cache_head,
 548					 cache_list);
 549			sunrpc_begin_cache_remove_entry(ch, detail);
 550			spin_unlock(&detail->hash_lock);
 551			sunrpc_end_cache_remove_entry(ch, detail);
 552			spin_lock(&detail->hash_lock);
 553		}
 554	}
 555	spin_unlock(&detail->hash_lock);
 556}
 557EXPORT_SYMBOL_GPL(cache_purge);
 558
 559
 560/*
 561 * Deferral and Revisiting of Requests.
 562 *
 563 * If a cache lookup finds a pending entry, we
 564 * need to defer the request and revisit it later.
 565 * All deferred requests are stored in a hash table,
 566 * indexed by "struct cache_head *".
 567 * As it may be wasteful to store a whole request
 568 * structure, we allow the request to provide a
 569 * deferred form, which must contain a
 570 * 'struct cache_deferred_req'
 571 * This cache_deferred_req contains a method to allow
 572 * it to be revisited when cache info is available
 573 */
 574
 575#define	DFR_HASHSIZE	(PAGE_SIZE/sizeof(struct list_head))
 576#define	DFR_HASH(item)	((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE)
 577
 578#define	DFR_MAX	300	/* ??? */
 579
 580static DEFINE_SPINLOCK(cache_defer_lock);
 581static LIST_HEAD(cache_defer_list);
 582static struct hlist_head cache_defer_hash[DFR_HASHSIZE];
 583static int cache_defer_cnt;
 584
 585static void __unhash_deferred_req(struct cache_deferred_req *dreq)
 586{
 587	hlist_del_init(&dreq->hash);
 588	if (!list_empty(&dreq->recent)) {
 589		list_del_init(&dreq->recent);
 590		cache_defer_cnt--;
 591	}
 592}
 593
 594static void __hash_deferred_req(struct cache_deferred_req *dreq, struct cache_head *item)
 595{
 596	int hash = DFR_HASH(item);
 597
 598	INIT_LIST_HEAD(&dreq->recent);
 599	hlist_add_head(&dreq->hash, &cache_defer_hash[hash]);
 600}
 601
 602static void setup_deferral(struct cache_deferred_req *dreq,
 603			   struct cache_head *item,
 604			   int count_me)
 605{
 606
 607	dreq->item = item;
 608
 609	spin_lock(&cache_defer_lock);
 610
 611	__hash_deferred_req(dreq, item);
 612
 613	if (count_me) {
 614		cache_defer_cnt++;
 615		list_add(&dreq->recent, &cache_defer_list);
 616	}
 617
 618	spin_unlock(&cache_defer_lock);
 619
 620}
 621
 622struct thread_deferred_req {
 623	struct cache_deferred_req handle;
 624	struct completion completion;
 625};
 626
 627static void cache_restart_thread(struct cache_deferred_req *dreq, int too_many)
 628{
 629	struct thread_deferred_req *dr =
 630		container_of(dreq, struct thread_deferred_req, handle);
 631	complete(&dr->completion);
 632}
 633
 634static void cache_wait_req(struct cache_req *req, struct cache_head *item)
 635{
 636	struct thread_deferred_req sleeper;
 637	struct cache_deferred_req *dreq = &sleeper.handle;
 638
 639	sleeper.completion = COMPLETION_INITIALIZER_ONSTACK(sleeper.completion);
 640	dreq->revisit = cache_restart_thread;
 641
 642	setup_deferral(dreq, item, 0);
 643
 644	if (!test_bit(CACHE_PENDING, &item->flags) ||
 645	    wait_for_completion_interruptible_timeout(
 646		    &sleeper.completion, req->thread_wait) <= 0) {
 647		/* The completion wasn't completed, so we need
 648		 * to clean up
 649		 */
 650		spin_lock(&cache_defer_lock);
 651		if (!hlist_unhashed(&sleeper.handle.hash)) {
 652			__unhash_deferred_req(&sleeper.handle);
 653			spin_unlock(&cache_defer_lock);
 654		} else {
 655			/* cache_revisit_request already removed
 656			 * this from the hash table, but hasn't
 657			 * called ->revisit yet.  It will very soon
 658			 * and we need to wait for it.
 659			 */
 660			spin_unlock(&cache_defer_lock);
 661			wait_for_completion(&sleeper.completion);
 662		}
 663	}
 664}
 665
 666static void cache_limit_defers(void)
 667{
 668	/* Make sure we haven't exceed the limit of allowed deferred
 669	 * requests.
 670	 */
 671	struct cache_deferred_req *discard = NULL;
 672
 673	if (cache_defer_cnt <= DFR_MAX)
 674		return;
 675
 676	spin_lock(&cache_defer_lock);
 677
 678	/* Consider removing either the first or the last */
 679	if (cache_defer_cnt > DFR_MAX) {
 680		if (get_random_u32_below(2))
 681			discard = list_entry(cache_defer_list.next,
 682					     struct cache_deferred_req, recent);
 683		else
 684			discard = list_entry(cache_defer_list.prev,
 685					     struct cache_deferred_req, recent);
 686		__unhash_deferred_req(discard);
 687	}
 688	spin_unlock(&cache_defer_lock);
 689	if (discard)
 690		discard->revisit(discard, 1);
 691}
 692
 693#if IS_ENABLED(CONFIG_FAIL_SUNRPC)
 694static inline bool cache_defer_immediately(void)
 695{
 696	return !fail_sunrpc.ignore_cache_wait &&
 697		should_fail(&fail_sunrpc.attr, 1);
 698}
 699#else
 700static inline bool cache_defer_immediately(void)
 701{
 702	return false;
 703}
 704#endif
 705
 706/* Return true if and only if a deferred request is queued. */
 707static bool cache_defer_req(struct cache_req *req, struct cache_head *item)
 708{
 709	struct cache_deferred_req *dreq;
 710
 711	if (!cache_defer_immediately()) {
 712		cache_wait_req(req, item);
 713		if (!test_bit(CACHE_PENDING, &item->flags))
 714			return false;
 715	}
 716
 717	dreq = req->defer(req);
 718	if (dreq == NULL)
 719		return false;
 720	setup_deferral(dreq, item, 1);
 721	if (!test_bit(CACHE_PENDING, &item->flags))
 722		/* Bit could have been cleared before we managed to
 723		 * set up the deferral, so need to revisit just in case
 724		 */
 725		cache_revisit_request(item);
 726
 727	cache_limit_defers();
 728	return true;
 729}
 730
 731static void cache_revisit_request(struct cache_head *item)
 732{
 733	struct cache_deferred_req *dreq;
 734	struct list_head pending;
 735	struct hlist_node *tmp;
 736	int hash = DFR_HASH(item);
 737
 738	INIT_LIST_HEAD(&pending);
 739	spin_lock(&cache_defer_lock);
 740
 741	hlist_for_each_entry_safe(dreq, tmp, &cache_defer_hash[hash], hash)
 742		if (dreq->item == item) {
 743			__unhash_deferred_req(dreq);
 744			list_add(&dreq->recent, &pending);
 745		}
 746
 747	spin_unlock(&cache_defer_lock);
 748
 749	while (!list_empty(&pending)) {
 750		dreq = list_entry(pending.next, struct cache_deferred_req, recent);
 751		list_del_init(&dreq->recent);
 752		dreq->revisit(dreq, 0);
 753	}
 754}
 755
 756void cache_clean_deferred(void *owner)
 757{
 758	struct cache_deferred_req *dreq, *tmp;
 759	struct list_head pending;
 760
 761
 762	INIT_LIST_HEAD(&pending);
 763	spin_lock(&cache_defer_lock);
 764
 765	list_for_each_entry_safe(dreq, tmp, &cache_defer_list, recent) {
 766		if (dreq->owner == owner) {
 767			__unhash_deferred_req(dreq);
 768			list_add(&dreq->recent, &pending);
 769		}
 770	}
 771	spin_unlock(&cache_defer_lock);
 772
 773	while (!list_empty(&pending)) {
 774		dreq = list_entry(pending.next, struct cache_deferred_req, recent);
 775		list_del_init(&dreq->recent);
 776		dreq->revisit(dreq, 1);
 777	}
 778}
 779
 780/*
 781 * communicate with user-space
 782 *
 783 * We have a magic /proc file - /proc/net/rpc/<cachename>/channel.
 784 * On read, you get a full request, or block.
 785 * On write, an update request is processed.
 786 * Poll works if anything to read, and always allows write.
 787 *
 788 * Implemented by linked list of requests.  Each open file has
 789 * a ->private that also exists in this list.  New requests are added
 790 * to the end and may wakeup and preceding readers.
 791 * New readers are added to the head.  If, on read, an item is found with
 792 * CACHE_UPCALLING clear, we free it from the list.
 793 *
 794 */
 795
 796static DEFINE_SPINLOCK(queue_lock);
 
 797
 798struct cache_queue {
 799	struct list_head	list;
 800	int			reader;	/* if 0, then request */
 801};
 802struct cache_request {
 803	struct cache_queue	q;
 804	struct cache_head	*item;
 805	char			* buf;
 806	int			len;
 807	int			readers;
 808};
 809struct cache_reader {
 810	struct cache_queue	q;
 811	int			offset;	/* if non-0, we have a refcnt on next request */
 812};
 813
 814static int cache_request(struct cache_detail *detail,
 815			       struct cache_request *crq)
 816{
 817	char *bp = crq->buf;
 818	int len = PAGE_SIZE;
 819
 820	detail->cache_request(detail, crq->item, &bp, &len);
 821	if (len < 0)
 822		return -E2BIG;
 823	return PAGE_SIZE - len;
 824}
 825
 826static ssize_t cache_read(struct file *filp, char __user *buf, size_t count,
 827			  loff_t *ppos, struct cache_detail *cd)
 828{
 829	struct cache_reader *rp = filp->private_data;
 830	struct cache_request *rq;
 831	struct inode *inode = file_inode(filp);
 832	int err;
 833
 834	if (count == 0)
 835		return 0;
 836
 837	inode_lock(inode); /* protect against multiple concurrent
 838			      * readers on this file */
 839 again:
 840	spin_lock(&queue_lock);
 841	/* need to find next request */
 842	while (rp->q.list.next != &cd->queue &&
 843	       list_entry(rp->q.list.next, struct cache_queue, list)
 844	       ->reader) {
 845		struct list_head *next = rp->q.list.next;
 846		list_move(&rp->q.list, next);
 847	}
 848	if (rp->q.list.next == &cd->queue) {
 849		spin_unlock(&queue_lock);
 850		inode_unlock(inode);
 851		WARN_ON_ONCE(rp->offset);
 852		return 0;
 853	}
 854	rq = container_of(rp->q.list.next, struct cache_request, q.list);
 855	WARN_ON_ONCE(rq->q.reader);
 856	if (rp->offset == 0)
 857		rq->readers++;
 858	spin_unlock(&queue_lock);
 859
 860	if (rq->len == 0) {
 861		err = cache_request(cd, rq);
 862		if (err < 0)
 863			goto out;
 864		rq->len = err;
 865	}
 866
 867	if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) {
 868		err = -EAGAIN;
 869		spin_lock(&queue_lock);
 870		list_move(&rp->q.list, &rq->q.list);
 871		spin_unlock(&queue_lock);
 872	} else {
 873		if (rp->offset + count > rq->len)
 874			count = rq->len - rp->offset;
 875		err = -EFAULT;
 876		if (copy_to_user(buf, rq->buf + rp->offset, count))
 877			goto out;
 878		rp->offset += count;
 879		if (rp->offset >= rq->len) {
 880			rp->offset = 0;
 881			spin_lock(&queue_lock);
 882			list_move(&rp->q.list, &rq->q.list);
 883			spin_unlock(&queue_lock);
 884		}
 885		err = 0;
 886	}
 887 out:
 888	if (rp->offset == 0) {
 889		/* need to release rq */
 890		spin_lock(&queue_lock);
 891		rq->readers--;
 892		if (rq->readers == 0 &&
 893		    !test_bit(CACHE_PENDING, &rq->item->flags)) {
 894			list_del(&rq->q.list);
 895			spin_unlock(&queue_lock);
 896			cache_put(rq->item, cd);
 897			kfree(rq->buf);
 898			kfree(rq);
 899		} else
 900			spin_unlock(&queue_lock);
 901	}
 902	if (err == -EAGAIN)
 903		goto again;
 904	inode_unlock(inode);
 905	return err ? err :  count;
 906}
 907
 908static ssize_t cache_do_downcall(char *kaddr, const char __user *buf,
 909				 size_t count, struct cache_detail *cd)
 910{
 911	ssize_t ret;
 912
 913	if (count == 0)
 914		return -EINVAL;
 915	if (copy_from_user(kaddr, buf, count))
 916		return -EFAULT;
 917	kaddr[count] = '\0';
 918	ret = cd->cache_parse(cd, kaddr, count);
 919	if (!ret)
 920		ret = count;
 921	return ret;
 922}
 923
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 924static ssize_t cache_downcall(struct address_space *mapping,
 925			      const char __user *buf,
 926			      size_t count, struct cache_detail *cd)
 927{
 928	char *write_buf;
 
 929	ssize_t ret = -ENOMEM;
 930
 931	if (count >= 32768) { /* 32k is max userland buffer, lets check anyway */
 932		ret = -EINVAL;
 933		goto out;
 934	}
 935
 936	write_buf = kvmalloc(count + 1, GFP_KERNEL);
 937	if (!write_buf)
 938		goto out;
 939
 940	ret = cache_do_downcall(write_buf, buf, count, cd);
 941	kvfree(write_buf);
 942out:
 
 
 943	return ret;
 
 
 944}
 945
 946static ssize_t cache_write(struct file *filp, const char __user *buf,
 947			   size_t count, loff_t *ppos,
 948			   struct cache_detail *cd)
 949{
 950	struct address_space *mapping = filp->f_mapping;
 951	struct inode *inode = file_inode(filp);
 952	ssize_t ret = -EINVAL;
 953
 954	if (!cd->cache_parse)
 955		goto out;
 956
 957	inode_lock(inode);
 958	ret = cache_downcall(mapping, buf, count, cd);
 959	inode_unlock(inode);
 960out:
 961	return ret;
 962}
 963
 964static DECLARE_WAIT_QUEUE_HEAD(queue_wait);
 965
 966static __poll_t cache_poll(struct file *filp, poll_table *wait,
 967			       struct cache_detail *cd)
 968{
 969	__poll_t mask;
 970	struct cache_reader *rp = filp->private_data;
 971	struct cache_queue *cq;
 972
 973	poll_wait(filp, &queue_wait, wait);
 974
 975	/* alway allow write */
 976	mask = EPOLLOUT | EPOLLWRNORM;
 977
 978	if (!rp)
 979		return mask;
 980
 981	spin_lock(&queue_lock);
 982
 983	for (cq= &rp->q; &cq->list != &cd->queue;
 984	     cq = list_entry(cq->list.next, struct cache_queue, list))
 985		if (!cq->reader) {
 986			mask |= EPOLLIN | EPOLLRDNORM;
 987			break;
 988		}
 989	spin_unlock(&queue_lock);
 990	return mask;
 991}
 992
 993static int cache_ioctl(struct inode *ino, struct file *filp,
 994		       unsigned int cmd, unsigned long arg,
 995		       struct cache_detail *cd)
 996{
 997	int len = 0;
 998	struct cache_reader *rp = filp->private_data;
 999	struct cache_queue *cq;
1000
1001	if (cmd != FIONREAD || !rp)
1002		return -EINVAL;
1003
1004	spin_lock(&queue_lock);
1005
1006	/* only find the length remaining in current request,
1007	 * or the length of the next request
1008	 */
1009	for (cq= &rp->q; &cq->list != &cd->queue;
1010	     cq = list_entry(cq->list.next, struct cache_queue, list))
1011		if (!cq->reader) {
1012			struct cache_request *cr =
1013				container_of(cq, struct cache_request, q);
1014			len = cr->len - rp->offset;
1015			break;
1016		}
1017	spin_unlock(&queue_lock);
1018
1019	return put_user(len, (int __user *)arg);
1020}
1021
1022static int cache_open(struct inode *inode, struct file *filp,
1023		      struct cache_detail *cd)
1024{
1025	struct cache_reader *rp = NULL;
1026
1027	if (!cd || !try_module_get(cd->owner))
1028		return -EACCES;
1029	nonseekable_open(inode, filp);
1030	if (filp->f_mode & FMODE_READ) {
1031		rp = kmalloc(sizeof(*rp), GFP_KERNEL);
1032		if (!rp) {
1033			module_put(cd->owner);
1034			return -ENOMEM;
1035		}
1036		rp->offset = 0;
1037		rp->q.reader = 1;
1038
1039		spin_lock(&queue_lock);
1040		list_add(&rp->q.list, &cd->queue);
1041		spin_unlock(&queue_lock);
1042	}
1043	if (filp->f_mode & FMODE_WRITE)
1044		atomic_inc(&cd->writers);
1045	filp->private_data = rp;
1046	return 0;
1047}
1048
1049static int cache_release(struct inode *inode, struct file *filp,
1050			 struct cache_detail *cd)
1051{
1052	struct cache_reader *rp = filp->private_data;
1053
1054	if (rp) {
1055		spin_lock(&queue_lock);
1056		if (rp->offset) {
1057			struct cache_queue *cq;
1058			for (cq= &rp->q; &cq->list != &cd->queue;
1059			     cq = list_entry(cq->list.next, struct cache_queue, list))
1060				if (!cq->reader) {
1061					container_of(cq, struct cache_request, q)
1062						->readers--;
1063					break;
1064				}
1065			rp->offset = 0;
1066		}
1067		list_del(&rp->q.list);
1068		spin_unlock(&queue_lock);
1069
1070		filp->private_data = NULL;
1071		kfree(rp);
1072
1073	}
1074	if (filp->f_mode & FMODE_WRITE) {
1075		atomic_dec(&cd->writers);
1076		cd->last_close = seconds_since_boot();
1077	}
1078	module_put(cd->owner);
1079	return 0;
1080}
1081
1082
1083
1084static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch)
1085{
1086	struct cache_queue *cq, *tmp;
1087	struct cache_request *cr;
1088	struct list_head dequeued;
1089
1090	INIT_LIST_HEAD(&dequeued);
1091	spin_lock(&queue_lock);
1092	list_for_each_entry_safe(cq, tmp, &detail->queue, list)
1093		if (!cq->reader) {
1094			cr = container_of(cq, struct cache_request, q);
1095			if (cr->item != ch)
1096				continue;
1097			if (test_bit(CACHE_PENDING, &ch->flags))
1098				/* Lost a race and it is pending again */
1099				break;
1100			if (cr->readers != 0)
1101				continue;
1102			list_move(&cr->q.list, &dequeued);
1103		}
1104	spin_unlock(&queue_lock);
1105	while (!list_empty(&dequeued)) {
1106		cr = list_entry(dequeued.next, struct cache_request, q.list);
1107		list_del(&cr->q.list);
1108		cache_put(cr->item, detail);
1109		kfree(cr->buf);
1110		kfree(cr);
1111	}
1112}
1113
1114/*
1115 * Support routines for text-based upcalls.
1116 * Fields are separated by spaces.
1117 * Fields are either mangled to quote space tab newline slosh with slosh
1118 * or a hexified with a leading \x
1119 * Record is terminated with newline.
1120 *
1121 */
1122
1123void qword_add(char **bpp, int *lp, char *str)
1124{
1125	char *bp = *bpp;
1126	int len = *lp;
1127	int ret;
1128
1129	if (len < 0) return;
1130
1131	ret = string_escape_str(str, bp, len, ESCAPE_OCTAL, "\\ \n\t");
1132	if (ret >= len) {
1133		bp += len;
1134		len = -1;
1135	} else {
1136		bp += ret;
1137		len -= ret;
1138		*bp++ = ' ';
1139		len--;
1140	}
1141	*bpp = bp;
1142	*lp = len;
1143}
1144EXPORT_SYMBOL_GPL(qword_add);
1145
1146void qword_addhex(char **bpp, int *lp, char *buf, int blen)
1147{
1148	char *bp = *bpp;
1149	int len = *lp;
1150
1151	if (len < 0) return;
1152
1153	if (len > 2) {
1154		*bp++ = '\\';
1155		*bp++ = 'x';
1156		len -= 2;
1157		while (blen && len >= 2) {
1158			bp = hex_byte_pack(bp, *buf++);
1159			len -= 2;
1160			blen--;
1161		}
1162	}
1163	if (blen || len<1) len = -1;
1164	else {
1165		*bp++ = ' ';
1166		len--;
1167	}
1168	*bpp = bp;
1169	*lp = len;
1170}
1171EXPORT_SYMBOL_GPL(qword_addhex);
1172
1173static void warn_no_listener(struct cache_detail *detail)
1174{
1175	if (detail->last_warn != detail->last_close) {
1176		detail->last_warn = detail->last_close;
1177		if (detail->warn_no_listener)
1178			detail->warn_no_listener(detail, detail->last_close != 0);
1179	}
1180}
1181
1182static bool cache_listeners_exist(struct cache_detail *detail)
1183{
1184	if (atomic_read(&detail->writers))
1185		return true;
1186	if (detail->last_close == 0)
1187		/* This cache was never opened */
1188		return false;
1189	if (detail->last_close < seconds_since_boot() - 30)
1190		/*
1191		 * We allow for the possibility that someone might
1192		 * restart a userspace daemon without restarting the
1193		 * server; but after 30 seconds, we give up.
1194		 */
1195		 return false;
1196	return true;
1197}
1198
1199/*
1200 * register an upcall request to user-space and queue it up for read() by the
1201 * upcall daemon.
1202 *
1203 * Each request is at most one page long.
1204 */
1205static int cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h)
1206{
1207	char *buf;
1208	struct cache_request *crq;
1209	int ret = 0;
1210
1211	if (test_bit(CACHE_CLEANED, &h->flags))
1212		/* Too late to make an upcall */
1213		return -EAGAIN;
1214
1215	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
1216	if (!buf)
1217		return -EAGAIN;
1218
1219	crq = kmalloc(sizeof (*crq), GFP_KERNEL);
1220	if (!crq) {
1221		kfree(buf);
1222		return -EAGAIN;
1223	}
1224
1225	crq->q.reader = 0;
1226	crq->buf = buf;
1227	crq->len = 0;
1228	crq->readers = 0;
1229	spin_lock(&queue_lock);
1230	if (test_bit(CACHE_PENDING, &h->flags)) {
1231		crq->item = cache_get(h);
1232		list_add_tail(&crq->q.list, &detail->queue);
1233		trace_cache_entry_upcall(detail, h);
1234	} else
1235		/* Lost a race, no longer PENDING, so don't enqueue */
1236		ret = -EAGAIN;
1237	spin_unlock(&queue_lock);
1238	wake_up(&queue_wait);
1239	if (ret == -EAGAIN) {
1240		kfree(buf);
1241		kfree(crq);
1242	}
1243	return ret;
1244}
1245
1246int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h)
1247{
1248	if (test_and_set_bit(CACHE_PENDING, &h->flags))
1249		return 0;
1250	return cache_pipe_upcall(detail, h);
1251}
1252EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall);
1253
1254int sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
1255				     struct cache_head *h)
1256{
1257	if (!cache_listeners_exist(detail)) {
1258		warn_no_listener(detail);
1259		trace_cache_entry_no_listener(detail, h);
1260		return -EINVAL;
1261	}
1262	return sunrpc_cache_pipe_upcall(detail, h);
1263}
1264EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall_timeout);
1265
1266/*
1267 * parse a message from user-space and pass it
1268 * to an appropriate cache
1269 * Messages are, like requests, separated into fields by
1270 * spaces and dequotes as \xHEXSTRING or embedded \nnn octal
1271 *
1272 * Message is
1273 *   reply cachename expiry key ... content....
1274 *
1275 * key and content are both parsed by cache
1276 */
1277
1278int qword_get(char **bpp, char *dest, int bufsize)
1279{
1280	/* return bytes copied, or -1 on error */
1281	char *bp = *bpp;
1282	int len = 0;
1283
1284	while (*bp == ' ') bp++;
1285
1286	if (bp[0] == '\\' && bp[1] == 'x') {
1287		/* HEX STRING */
1288		bp += 2;
1289		while (len < bufsize - 1) {
1290			int h, l;
1291
1292			h = hex_to_bin(bp[0]);
1293			if (h < 0)
1294				break;
1295
1296			l = hex_to_bin(bp[1]);
1297			if (l < 0)
1298				break;
1299
1300			*dest++ = (h << 4) | l;
1301			bp += 2;
1302			len++;
1303		}
1304	} else {
1305		/* text with \nnn octal quoting */
1306		while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) {
1307			if (*bp == '\\' &&
1308			    isodigit(bp[1]) && (bp[1] <= '3') &&
1309			    isodigit(bp[2]) &&
1310			    isodigit(bp[3])) {
1311				int byte = (*++bp -'0');
1312				bp++;
1313				byte = (byte << 3) | (*bp++ - '0');
1314				byte = (byte << 3) | (*bp++ - '0');
1315				*dest++ = byte;
1316				len++;
1317			} else {
1318				*dest++ = *bp++;
1319				len++;
1320			}
1321		}
1322	}
1323
1324	if (*bp != ' ' && *bp != '\n' && *bp != '\0')
1325		return -1;
1326	while (*bp == ' ') bp++;
1327	*bpp = bp;
1328	*dest = '\0';
1329	return len;
1330}
1331EXPORT_SYMBOL_GPL(qword_get);
1332
1333
1334/*
1335 * support /proc/net/rpc/$CACHENAME/content
1336 * as a seqfile.
1337 * We call ->cache_show passing NULL for the item to
1338 * get a header, then pass each real item in the cache
1339 */
1340
1341static void *__cache_seq_start(struct seq_file *m, loff_t *pos)
1342{
1343	loff_t n = *pos;
1344	unsigned int hash, entry;
1345	struct cache_head *ch;
1346	struct cache_detail *cd = m->private;
1347
1348	if (!n--)
1349		return SEQ_START_TOKEN;
1350	hash = n >> 32;
1351	entry = n & ((1LL<<32) - 1);
1352
1353	hlist_for_each_entry_rcu(ch, &cd->hash_table[hash], cache_list)
1354		if (!entry--)
1355			return ch;
1356	n &= ~((1LL<<32) - 1);
1357	do {
1358		hash++;
1359		n += 1LL<<32;
1360	} while(hash < cd->hash_size &&
1361		hlist_empty(&cd->hash_table[hash]));
1362	if (hash >= cd->hash_size)
1363		return NULL;
1364	*pos = n+1;
1365	return hlist_entry_safe(rcu_dereference_raw(
1366				hlist_first_rcu(&cd->hash_table[hash])),
1367				struct cache_head, cache_list);
1368}
1369
1370static void *cache_seq_next(struct seq_file *m, void *p, loff_t *pos)
1371{
1372	struct cache_head *ch = p;
1373	int hash = (*pos >> 32);
1374	struct cache_detail *cd = m->private;
1375
1376	if (p == SEQ_START_TOKEN)
1377		hash = 0;
1378	else if (ch->cache_list.next == NULL) {
1379		hash++;
1380		*pos += 1LL<<32;
1381	} else {
1382		++*pos;
1383		return hlist_entry_safe(rcu_dereference_raw(
1384					hlist_next_rcu(&ch->cache_list)),
1385					struct cache_head, cache_list);
1386	}
1387	*pos &= ~((1LL<<32) - 1);
1388	while (hash < cd->hash_size &&
1389	       hlist_empty(&cd->hash_table[hash])) {
1390		hash++;
1391		*pos += 1LL<<32;
1392	}
1393	if (hash >= cd->hash_size)
1394		return NULL;
1395	++*pos;
1396	return hlist_entry_safe(rcu_dereference_raw(
1397				hlist_first_rcu(&cd->hash_table[hash])),
1398				struct cache_head, cache_list);
1399}
1400
1401void *cache_seq_start_rcu(struct seq_file *m, loff_t *pos)
1402	__acquires(RCU)
1403{
1404	rcu_read_lock();
1405	return __cache_seq_start(m, pos);
1406}
1407EXPORT_SYMBOL_GPL(cache_seq_start_rcu);
1408
1409void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos)
1410{
1411	return cache_seq_next(file, p, pos);
1412}
1413EXPORT_SYMBOL_GPL(cache_seq_next_rcu);
1414
1415void cache_seq_stop_rcu(struct seq_file *m, void *p)
1416	__releases(RCU)
1417{
1418	rcu_read_unlock();
1419}
1420EXPORT_SYMBOL_GPL(cache_seq_stop_rcu);
1421
1422static int c_show(struct seq_file *m, void *p)
1423{
1424	struct cache_head *cp = p;
1425	struct cache_detail *cd = m->private;
1426
1427	if (p == SEQ_START_TOKEN)
1428		return cd->cache_show(m, cd, NULL);
1429
1430	ifdebug(CACHE)
1431		seq_printf(m, "# expiry=%lld refcnt=%d flags=%lx\n",
1432			   convert_to_wallclock(cp->expiry_time),
1433			   kref_read(&cp->ref), cp->flags);
1434	cache_get(cp);
1435	if (cache_check(cd, cp, NULL))
1436		/* cache_check does a cache_put on failure */
1437		seq_puts(m, "# ");
1438	else {
1439		if (cache_is_expired(cd, cp))
1440			seq_puts(m, "# ");
1441		cache_put(cp, cd);
1442	}
1443
1444	return cd->cache_show(m, cd, cp);
1445}
1446
1447static const struct seq_operations cache_content_op = {
1448	.start	= cache_seq_start_rcu,
1449	.next	= cache_seq_next_rcu,
1450	.stop	= cache_seq_stop_rcu,
1451	.show	= c_show,
1452};
1453
1454static int content_open(struct inode *inode, struct file *file,
1455			struct cache_detail *cd)
1456{
1457	struct seq_file *seq;
1458	int err;
1459
1460	if (!cd || !try_module_get(cd->owner))
1461		return -EACCES;
1462
1463	err = seq_open(file, &cache_content_op);
1464	if (err) {
1465		module_put(cd->owner);
1466		return err;
1467	}
1468
1469	seq = file->private_data;
1470	seq->private = cd;
1471	return 0;
1472}
1473
1474static int content_release(struct inode *inode, struct file *file,
1475		struct cache_detail *cd)
1476{
1477	int ret = seq_release(inode, file);
1478	module_put(cd->owner);
1479	return ret;
1480}
1481
1482static int open_flush(struct inode *inode, struct file *file,
1483			struct cache_detail *cd)
1484{
1485	if (!cd || !try_module_get(cd->owner))
1486		return -EACCES;
1487	return nonseekable_open(inode, file);
1488}
1489
1490static int release_flush(struct inode *inode, struct file *file,
1491			struct cache_detail *cd)
1492{
1493	module_put(cd->owner);
1494	return 0;
1495}
1496
1497static ssize_t read_flush(struct file *file, char __user *buf,
1498			  size_t count, loff_t *ppos,
1499			  struct cache_detail *cd)
1500{
1501	char tbuf[22];
1502	size_t len;
1503
1504	len = snprintf(tbuf, sizeof(tbuf), "%llu\n",
1505			convert_to_wallclock(cd->flush_time));
1506	return simple_read_from_buffer(buf, count, ppos, tbuf, len);
1507}
1508
1509static ssize_t write_flush(struct file *file, const char __user *buf,
1510			   size_t count, loff_t *ppos,
1511			   struct cache_detail *cd)
1512{
1513	char tbuf[20];
1514	char *ep;
1515	time64_t now;
1516
1517	if (*ppos || count > sizeof(tbuf)-1)
1518		return -EINVAL;
1519	if (copy_from_user(tbuf, buf, count))
1520		return -EFAULT;
1521	tbuf[count] = 0;
1522	simple_strtoul(tbuf, &ep, 0);
1523	if (*ep && *ep != '\n')
1524		return -EINVAL;
1525	/* Note that while we check that 'buf' holds a valid number,
1526	 * we always ignore the value and just flush everything.
1527	 * Making use of the number leads to races.
1528	 */
1529
1530	now = seconds_since_boot();
1531	/* Always flush everything, so behave like cache_purge()
1532	 * Do this by advancing flush_time to the current time,
1533	 * or by one second if it has already reached the current time.
1534	 * Newly added cache entries will always have ->last_refresh greater
1535	 * that ->flush_time, so they don't get flushed prematurely.
1536	 */
1537
1538	if (cd->flush_time >= now)
1539		now = cd->flush_time + 1;
1540
1541	cd->flush_time = now;
1542	cd->nextcheck = now;
1543	cache_flush();
1544
1545	if (cd->flush)
1546		cd->flush();
1547
1548	*ppos += count;
1549	return count;
1550}
1551
1552static ssize_t cache_read_procfs(struct file *filp, char __user *buf,
1553				 size_t count, loff_t *ppos)
1554{
1555	struct cache_detail *cd = pde_data(file_inode(filp));
1556
1557	return cache_read(filp, buf, count, ppos, cd);
1558}
1559
1560static ssize_t cache_write_procfs(struct file *filp, const char __user *buf,
1561				  size_t count, loff_t *ppos)
1562{
1563	struct cache_detail *cd = pde_data(file_inode(filp));
1564
1565	return cache_write(filp, buf, count, ppos, cd);
1566}
1567
1568static __poll_t cache_poll_procfs(struct file *filp, poll_table *wait)
1569{
1570	struct cache_detail *cd = pde_data(file_inode(filp));
1571
1572	return cache_poll(filp, wait, cd);
1573}
1574
1575static long cache_ioctl_procfs(struct file *filp,
1576			       unsigned int cmd, unsigned long arg)
1577{
1578	struct inode *inode = file_inode(filp);
1579	struct cache_detail *cd = pde_data(inode);
1580
1581	return cache_ioctl(inode, filp, cmd, arg, cd);
1582}
1583
1584static int cache_open_procfs(struct inode *inode, struct file *filp)
1585{
1586	struct cache_detail *cd = pde_data(inode);
1587
1588	return cache_open(inode, filp, cd);
1589}
1590
1591static int cache_release_procfs(struct inode *inode, struct file *filp)
1592{
1593	struct cache_detail *cd = pde_data(inode);
1594
1595	return cache_release(inode, filp, cd);
1596}
1597
1598static const struct proc_ops cache_channel_proc_ops = {
1599	.proc_lseek	= no_llseek,
1600	.proc_read	= cache_read_procfs,
1601	.proc_write	= cache_write_procfs,
1602	.proc_poll	= cache_poll_procfs,
1603	.proc_ioctl	= cache_ioctl_procfs, /* for FIONREAD */
1604	.proc_open	= cache_open_procfs,
1605	.proc_release	= cache_release_procfs,
1606};
1607
1608static int content_open_procfs(struct inode *inode, struct file *filp)
1609{
1610	struct cache_detail *cd = pde_data(inode);
1611
1612	return content_open(inode, filp, cd);
1613}
1614
1615static int content_release_procfs(struct inode *inode, struct file *filp)
1616{
1617	struct cache_detail *cd = pde_data(inode);
1618
1619	return content_release(inode, filp, cd);
1620}
1621
1622static const struct proc_ops content_proc_ops = {
1623	.proc_open	= content_open_procfs,
1624	.proc_read	= seq_read,
1625	.proc_lseek	= seq_lseek,
1626	.proc_release	= content_release_procfs,
1627};
1628
1629static int open_flush_procfs(struct inode *inode, struct file *filp)
1630{
1631	struct cache_detail *cd = pde_data(inode);
1632
1633	return open_flush(inode, filp, cd);
1634}
1635
1636static int release_flush_procfs(struct inode *inode, struct file *filp)
1637{
1638	struct cache_detail *cd = pde_data(inode);
1639
1640	return release_flush(inode, filp, cd);
1641}
1642
1643static ssize_t read_flush_procfs(struct file *filp, char __user *buf,
1644			    size_t count, loff_t *ppos)
1645{
1646	struct cache_detail *cd = pde_data(file_inode(filp));
1647
1648	return read_flush(filp, buf, count, ppos, cd);
1649}
1650
1651static ssize_t write_flush_procfs(struct file *filp,
1652				  const char __user *buf,
1653				  size_t count, loff_t *ppos)
1654{
1655	struct cache_detail *cd = pde_data(file_inode(filp));
1656
1657	return write_flush(filp, buf, count, ppos, cd);
1658}
1659
1660static const struct proc_ops cache_flush_proc_ops = {
1661	.proc_open	= open_flush_procfs,
1662	.proc_read	= read_flush_procfs,
1663	.proc_write	= write_flush_procfs,
1664	.proc_release	= release_flush_procfs,
1665	.proc_lseek	= no_llseek,
1666};
1667
1668static void remove_cache_proc_entries(struct cache_detail *cd)
1669{
1670	if (cd->procfs) {
1671		proc_remove(cd->procfs);
1672		cd->procfs = NULL;
1673	}
1674}
1675
1676#ifdef CONFIG_PROC_FS
1677static int create_cache_proc_entries(struct cache_detail *cd, struct net *net)
1678{
1679	struct proc_dir_entry *p;
1680	struct sunrpc_net *sn;
1681
1682	sn = net_generic(net, sunrpc_net_id);
1683	cd->procfs = proc_mkdir(cd->name, sn->proc_net_rpc);
1684	if (cd->procfs == NULL)
1685		goto out_nomem;
1686
1687	p = proc_create_data("flush", S_IFREG | 0600,
1688			     cd->procfs, &cache_flush_proc_ops, cd);
1689	if (p == NULL)
1690		goto out_nomem;
1691
1692	if (cd->cache_request || cd->cache_parse) {
1693		p = proc_create_data("channel", S_IFREG | 0600, cd->procfs,
1694				     &cache_channel_proc_ops, cd);
1695		if (p == NULL)
1696			goto out_nomem;
1697	}
1698	if (cd->cache_show) {
1699		p = proc_create_data("content", S_IFREG | 0400, cd->procfs,
1700				     &content_proc_ops, cd);
1701		if (p == NULL)
1702			goto out_nomem;
1703	}
1704	return 0;
1705out_nomem:
1706	remove_cache_proc_entries(cd);
1707	return -ENOMEM;
1708}
1709#else /* CONFIG_PROC_FS */
1710static int create_cache_proc_entries(struct cache_detail *cd, struct net *net)
1711{
1712	return 0;
1713}
1714#endif
1715
1716void __init cache_initialize(void)
1717{
1718	INIT_DEFERRABLE_WORK(&cache_cleaner, do_cache_clean);
1719}
1720
1721int cache_register_net(struct cache_detail *cd, struct net *net)
1722{
1723	int ret;
1724
1725	sunrpc_init_cache_detail(cd);
1726	ret = create_cache_proc_entries(cd, net);
1727	if (ret)
1728		sunrpc_destroy_cache_detail(cd);
1729	return ret;
1730}
1731EXPORT_SYMBOL_GPL(cache_register_net);
1732
1733void cache_unregister_net(struct cache_detail *cd, struct net *net)
1734{
1735	remove_cache_proc_entries(cd);
1736	sunrpc_destroy_cache_detail(cd);
1737}
1738EXPORT_SYMBOL_GPL(cache_unregister_net);
1739
1740struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net)
1741{
1742	struct cache_detail *cd;
1743	int i;
1744
1745	cd = kmemdup(tmpl, sizeof(struct cache_detail), GFP_KERNEL);
1746	if (cd == NULL)
1747		return ERR_PTR(-ENOMEM);
1748
1749	cd->hash_table = kcalloc(cd->hash_size, sizeof(struct hlist_head),
1750				 GFP_KERNEL);
1751	if (cd->hash_table == NULL) {
1752		kfree(cd);
1753		return ERR_PTR(-ENOMEM);
1754	}
1755
1756	for (i = 0; i < cd->hash_size; i++)
1757		INIT_HLIST_HEAD(&cd->hash_table[i]);
1758	cd->net = net;
1759	return cd;
1760}
1761EXPORT_SYMBOL_GPL(cache_create_net);
1762
1763void cache_destroy_net(struct cache_detail *cd, struct net *net)
1764{
1765	kfree(cd->hash_table);
1766	kfree(cd);
1767}
1768EXPORT_SYMBOL_GPL(cache_destroy_net);
1769
1770static ssize_t cache_read_pipefs(struct file *filp, char __user *buf,
1771				 size_t count, loff_t *ppos)
1772{
1773	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1774
1775	return cache_read(filp, buf, count, ppos, cd);
1776}
1777
1778static ssize_t cache_write_pipefs(struct file *filp, const char __user *buf,
1779				  size_t count, loff_t *ppos)
1780{
1781	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1782
1783	return cache_write(filp, buf, count, ppos, cd);
1784}
1785
1786static __poll_t cache_poll_pipefs(struct file *filp, poll_table *wait)
1787{
1788	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1789
1790	return cache_poll(filp, wait, cd);
1791}
1792
1793static long cache_ioctl_pipefs(struct file *filp,
1794			      unsigned int cmd, unsigned long arg)
1795{
1796	struct inode *inode = file_inode(filp);
1797	struct cache_detail *cd = RPC_I(inode)->private;
1798
1799	return cache_ioctl(inode, filp, cmd, arg, cd);
1800}
1801
1802static int cache_open_pipefs(struct inode *inode, struct file *filp)
1803{
1804	struct cache_detail *cd = RPC_I(inode)->private;
1805
1806	return cache_open(inode, filp, cd);
1807}
1808
1809static int cache_release_pipefs(struct inode *inode, struct file *filp)
1810{
1811	struct cache_detail *cd = RPC_I(inode)->private;
1812
1813	return cache_release(inode, filp, cd);
1814}
1815
1816const struct file_operations cache_file_operations_pipefs = {
1817	.owner		= THIS_MODULE,
1818	.llseek		= no_llseek,
1819	.read		= cache_read_pipefs,
1820	.write		= cache_write_pipefs,
1821	.poll		= cache_poll_pipefs,
1822	.unlocked_ioctl	= cache_ioctl_pipefs, /* for FIONREAD */
1823	.open		= cache_open_pipefs,
1824	.release	= cache_release_pipefs,
1825};
1826
1827static int content_open_pipefs(struct inode *inode, struct file *filp)
1828{
1829	struct cache_detail *cd = RPC_I(inode)->private;
1830
1831	return content_open(inode, filp, cd);
1832}
1833
1834static int content_release_pipefs(struct inode *inode, struct file *filp)
1835{
1836	struct cache_detail *cd = RPC_I(inode)->private;
1837
1838	return content_release(inode, filp, cd);
1839}
1840
1841const struct file_operations content_file_operations_pipefs = {
1842	.open		= content_open_pipefs,
1843	.read		= seq_read,
1844	.llseek		= seq_lseek,
1845	.release	= content_release_pipefs,
1846};
1847
1848static int open_flush_pipefs(struct inode *inode, struct file *filp)
1849{
1850	struct cache_detail *cd = RPC_I(inode)->private;
1851
1852	return open_flush(inode, filp, cd);
1853}
1854
1855static int release_flush_pipefs(struct inode *inode, struct file *filp)
1856{
1857	struct cache_detail *cd = RPC_I(inode)->private;
1858
1859	return release_flush(inode, filp, cd);
1860}
1861
1862static ssize_t read_flush_pipefs(struct file *filp, char __user *buf,
1863			    size_t count, loff_t *ppos)
1864{
1865	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1866
1867	return read_flush(filp, buf, count, ppos, cd);
1868}
1869
1870static ssize_t write_flush_pipefs(struct file *filp,
1871				  const char __user *buf,
1872				  size_t count, loff_t *ppos)
1873{
1874	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1875
1876	return write_flush(filp, buf, count, ppos, cd);
1877}
1878
1879const struct file_operations cache_flush_operations_pipefs = {
1880	.open		= open_flush_pipefs,
1881	.read		= read_flush_pipefs,
1882	.write		= write_flush_pipefs,
1883	.release	= release_flush_pipefs,
1884	.llseek		= no_llseek,
1885};
1886
1887int sunrpc_cache_register_pipefs(struct dentry *parent,
1888				 const char *name, umode_t umode,
1889				 struct cache_detail *cd)
1890{
1891	struct dentry *dir = rpc_create_cache_dir(parent, name, umode, cd);
1892	if (IS_ERR(dir))
1893		return PTR_ERR(dir);
1894	cd->pipefs = dir;
1895	return 0;
1896}
1897EXPORT_SYMBOL_GPL(sunrpc_cache_register_pipefs);
1898
1899void sunrpc_cache_unregister_pipefs(struct cache_detail *cd)
1900{
1901	if (cd->pipefs) {
1902		rpc_remove_cache_dir(cd->pipefs);
1903		cd->pipefs = NULL;
1904	}
1905}
1906EXPORT_SYMBOL_GPL(sunrpc_cache_unregister_pipefs);
1907
1908void sunrpc_cache_unhash(struct cache_detail *cd, struct cache_head *h)
1909{
1910	spin_lock(&cd->hash_lock);
1911	if (!hlist_unhashed(&h->cache_list)){
1912		sunrpc_begin_cache_remove_entry(h, cd);
1913		spin_unlock(&cd->hash_lock);
1914		sunrpc_end_cache_remove_entry(h, cd);
1915	} else
1916		spin_unlock(&cd->hash_lock);
1917}
1918EXPORT_SYMBOL_GPL(sunrpc_cache_unhash);