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#include "netns.h"
  37
  38#define	 RPCDBG_FACILITY RPCDBG_CACHE
  39
  40static bool cache_defer_req(struct cache_req *req, struct cache_head *item);
  41static void cache_revisit_request(struct cache_head *item);
  42
  43static void cache_init(struct cache_head *h, struct cache_detail *detail)
  44{
  45	time64_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 void cache_fresh_unlocked(struct cache_head *head,
  57				struct cache_detail *detail);
  58
  59static struct cache_head *sunrpc_cache_find_rcu(struct cache_detail *detail,
  60						struct cache_head *key,
  61						int hash)
  62{
  63	struct hlist_head *head = &detail->hash_table[hash];
  64	struct cache_head *tmp;
  65
  66	rcu_read_lock();
  67	hlist_for_each_entry_rcu(tmp, head, cache_list) {
  68		if (!detail->match(tmp, key))
  69			continue;
  70		if (test_bit(CACHE_VALID, &tmp->flags) &&
  71		    cache_is_expired(detail, tmp))
  72			continue;
  73		tmp = cache_get_rcu(tmp);
  74		rcu_read_unlock();
  75		return tmp;
  76	}
  77	rcu_read_unlock();
  78	return NULL;
  79}
  80
  81static void sunrpc_begin_cache_remove_entry(struct cache_head *ch,
  82					    struct cache_detail *cd)
  83{
  84	/* Must be called under cd->hash_lock */
  85	hlist_del_init_rcu(&ch->cache_list);
  86	set_bit(CACHE_CLEANED, &ch->flags);
  87	cd->entries --;
  88}
  89
  90static void sunrpc_end_cache_remove_entry(struct cache_head *ch,
  91					  struct cache_detail *cd)
  92{
  93	cache_fresh_unlocked(ch, cd);
  94	cache_put(ch, cd);
  95}
  96
  97static struct cache_head *sunrpc_cache_add_entry(struct cache_detail *detail,
  98						 struct cache_head *key,
  99						 int hash)
 100{
 101	struct cache_head *new, *tmp, *freeme = NULL;
 102	struct hlist_head *head = &detail->hash_table[hash];
 
 
 
 
 
 
 
 
 
 103
 104	new = detail->alloc();
 105	if (!new)
 106		return NULL;
 107	/* must fully initialise 'new', else
 108	 * we might get lose if we need to
 109	 * cache_put it soon.
 110	 */
 111	cache_init(new, detail);
 112	detail->init(new, key);
 113
 114	spin_lock(&detail->hash_lock);
 115
 116	/* check if entry appeared while we slept */
 117	hlist_for_each_entry_rcu(tmp, head, cache_list,
 118				 lockdep_is_held(&detail->hash_lock)) {
 119		if (!detail->match(tmp, key))
 120			continue;
 121		if (test_bit(CACHE_VALID, &tmp->flags) &&
 122		    cache_is_expired(detail, tmp)) {
 123			sunrpc_begin_cache_remove_entry(tmp, detail);
 124			trace_cache_entry_expired(detail, tmp);
 125			freeme = tmp;
 126			break;
 
 
 
 
 127		}
 128		cache_get(tmp);
 129		spin_unlock(&detail->hash_lock);
 130		cache_put(new, detail);
 131		return tmp;
 132	}
 133
 134	hlist_add_head_rcu(&new->cache_list, head);
 135	detail->entries++;
 136	cache_get(new);
 137	spin_unlock(&detail->hash_lock);
 138
 139	if (freeme)
 140		sunrpc_end_cache_remove_entry(freeme, detail);
 141	return new;
 142}
 
 143
 144struct cache_head *sunrpc_cache_lookup_rcu(struct cache_detail *detail,
 145					   struct cache_head *key, int hash)
 146{
 147	struct cache_head *ret;
 148
 149	ret = sunrpc_cache_find_rcu(detail, key, hash);
 150	if (ret)
 151		return ret;
 152	/* Didn't find anything, insert an empty entry */
 153	return sunrpc_cache_add_entry(detail, key, hash);
 154}
 155EXPORT_SYMBOL_GPL(sunrpc_cache_lookup_rcu);
 156
 157static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch);
 158
 159static void cache_fresh_locked(struct cache_head *head, time64_t expiry,
 160			       struct cache_detail *detail)
 161{
 162	time64_t now = seconds_since_boot();
 163	if (now <= detail->flush_time)
 164		/* ensure it isn't immediately treated as expired */
 165		now = detail->flush_time + 1;
 166	head->expiry_time = expiry;
 167	head->last_refresh = now;
 168	smp_wmb(); /* paired with smp_rmb() in cache_is_valid() */
 169	set_bit(CACHE_VALID, &head->flags);
 170}
 171
 172static void cache_fresh_unlocked(struct cache_head *head,
 173				 struct cache_detail *detail)
 174{
 175	if (test_and_clear_bit(CACHE_PENDING, &head->flags)) {
 176		cache_revisit_request(head);
 177		cache_dequeue(detail, head);
 178	}
 179}
 180
 181static void cache_make_negative(struct cache_detail *detail,
 182				struct cache_head *h)
 183{
 184	set_bit(CACHE_NEGATIVE, &h->flags);
 185	trace_cache_entry_make_negative(detail, h);
 186}
 187
 188static void cache_entry_update(struct cache_detail *detail,
 189			       struct cache_head *h,
 190			       struct cache_head *new)
 191{
 192	if (!test_bit(CACHE_NEGATIVE, &new->flags)) {
 193		detail->update(h, new);
 194		trace_cache_entry_update(detail, h);
 195	} else {
 196		cache_make_negative(detail, h);
 197	}
 198}
 199
 200struct cache_head *sunrpc_cache_update(struct cache_detail *detail,
 201				       struct cache_head *new, struct cache_head *old, int hash)
 202{
 203	/* The 'old' entry is to be replaced by 'new'.
 204	 * If 'old' is not VALID, we update it directly,
 205	 * otherwise we need to replace it
 206	 */
 
 207	struct cache_head *tmp;
 208
 209	if (!test_bit(CACHE_VALID, &old->flags)) {
 210		spin_lock(&detail->hash_lock);
 211		if (!test_bit(CACHE_VALID, &old->flags)) {
 212			cache_entry_update(detail, old, new);
 213			cache_fresh_locked(old, new->expiry_time, detail);
 214			spin_unlock(&detail->hash_lock);
 
 
 
 215			cache_fresh_unlocked(old, detail);
 216			return old;
 217		}
 218		spin_unlock(&detail->hash_lock);
 219	}
 220	/* We need to insert a new entry */
 221	tmp = detail->alloc();
 222	if (!tmp) {
 223		cache_put(old, detail);
 224		return NULL;
 225	}
 226	cache_init(tmp, detail);
 227	detail->init(tmp, old);
 
 228
 229	spin_lock(&detail->hash_lock);
 230	cache_entry_update(detail, tmp, new);
 231	hlist_add_head(&tmp->cache_list, &detail->hash_table[hash]);
 
 
 
 
 232	detail->entries++;
 233	cache_get(tmp);
 234	cache_fresh_locked(tmp, new->expiry_time, detail);
 235	cache_fresh_locked(old, 0, detail);
 236	spin_unlock(&detail->hash_lock);
 237	cache_fresh_unlocked(tmp, detail);
 238	cache_fresh_unlocked(old, detail);
 239	cache_put(old, detail);
 240	return tmp;
 241}
 242EXPORT_SYMBOL_GPL(sunrpc_cache_update);
 243
 244static inline int cache_is_valid(struct cache_head *h)
 
 
 
 
 
 
 
 245{
 246	if (!test_bit(CACHE_VALID, &h->flags))
 247		return -EAGAIN;
 248	else {
 249		/* entry is valid */
 250		if (test_bit(CACHE_NEGATIVE, &h->flags))
 251			return -ENOENT;
 252		else {
 253			/*
 254			 * In combination with write barrier in
 255			 * sunrpc_cache_update, ensures that anyone
 256			 * using the cache entry after this sees the
 257			 * updated contents:
 258			 */
 259			smp_rmb();
 260			return 0;
 261		}
 262	}
 263}
 264
 265static int try_to_negate_entry(struct cache_detail *detail, struct cache_head *h)
 266{
 267	int rv;
 268
 269	spin_lock(&detail->hash_lock);
 270	rv = cache_is_valid(h);
 271	if (rv == -EAGAIN) {
 272		cache_make_negative(detail, h);
 273		cache_fresh_locked(h, seconds_since_boot()+CACHE_NEW_EXPIRY,
 274				   detail);
 275		rv = -ENOENT;
 276	}
 277	spin_unlock(&detail->hash_lock);
 
 
 278	cache_fresh_unlocked(h, detail);
 279	return rv;
 280}
 281
 282/*
 283 * This is the generic cache management routine for all
 284 * the authentication caches.
 285 * It checks the currency of a cache item and will (later)
 286 * initiate an upcall to fill it if needed.
 287 *
 288 *
 289 * Returns 0 if the cache_head can be used, or cache_puts it and returns
 290 * -EAGAIN if upcall is pending and request has been queued
 291 * -ETIMEDOUT if upcall failed or request could not be queue or
 292 *           upcall completed but item is still invalid (implying that
 293 *           the cache item has been replaced with a newer one).
 294 * -ENOENT if cache entry was negative
 295 */
 296int cache_check(struct cache_detail *detail,
 297		    struct cache_head *h, struct cache_req *rqstp)
 298{
 299	int rv;
 300	time64_t refresh_age, age;
 301
 302	/* First decide return status as best we can */
 303	rv = cache_is_valid(h);
 304
 305	/* now see if we want to start an upcall */
 306	refresh_age = (h->expiry_time - h->last_refresh);
 307	age = seconds_since_boot() - h->last_refresh;
 308
 309	if (rqstp == NULL) {
 310		if (rv == -EAGAIN)
 311			rv = -ENOENT;
 312	} else if (rv == -EAGAIN ||
 313		   (h->expiry_time != 0 && age > refresh_age/2)) {
 314		dprintk("RPC:       Want update, refage=%lld, age=%lld\n",
 315				refresh_age, age);
 316		switch (detail->cache_upcall(detail, h)) {
 317		case -EINVAL:
 318			rv = try_to_negate_entry(detail, h);
 319			break;
 320		case -EAGAIN:
 321			cache_fresh_unlocked(h, detail);
 322			break;
 
 
 
 
 
 323		}
 324	}
 325
 326	if (rv == -EAGAIN) {
 327		if (!cache_defer_req(rqstp, h)) {
 328			/*
 329			 * Request was not deferred; handle it as best
 330			 * we can ourselves:
 331			 */
 332			rv = cache_is_valid(h);
 333			if (rv == -EAGAIN)
 334				rv = -ETIMEDOUT;
 335		}
 336	}
 337	if (rv)
 338		cache_put(h, detail);
 339	return rv;
 340}
 341EXPORT_SYMBOL_GPL(cache_check);
 342
 343/*
 344 * caches need to be periodically cleaned.
 345 * For this we maintain a list of cache_detail and
 346 * a current pointer into that list and into the table
 347 * for that entry.
 348 *
 349 * Each time cache_clean is called it finds the next non-empty entry
 350 * in the current table and walks the list in that entry
 351 * looking for entries that can be removed.
 352 *
 353 * An entry gets removed if:
 354 * - The expiry is before current time
 355 * - The last_refresh time is before the flush_time for that cache
 356 *
 357 * later we might drop old entries with non-NEVER expiry if that table
 358 * is getting 'full' for some definition of 'full'
 359 *
 360 * The question of "how often to scan a table" is an interesting one
 361 * and is answered in part by the use of the "nextcheck" field in the
 362 * cache_detail.
 363 * When a scan of a table begins, the nextcheck field is set to a time
 364 * that is well into the future.
 365 * While scanning, if an expiry time is found that is earlier than the
 366 * current nextcheck time, nextcheck is set to that expiry time.
 367 * If the flush_time is ever set to a time earlier than the nextcheck
 368 * time, the nextcheck time is then set to that flush_time.
 369 *
 370 * A table is then only scanned if the current time is at least
 371 * the nextcheck time.
 372 *
 373 */
 374
 375static LIST_HEAD(cache_list);
 376static DEFINE_SPINLOCK(cache_list_lock);
 377static struct cache_detail *current_detail;
 378static int current_index;
 379
 380static void do_cache_clean(struct work_struct *work);
 381static struct delayed_work cache_cleaner;
 382
 383void sunrpc_init_cache_detail(struct cache_detail *cd)
 384{
 385	spin_lock_init(&cd->hash_lock);
 386	INIT_LIST_HEAD(&cd->queue);
 387	spin_lock(&cache_list_lock);
 388	cd->nextcheck = 0;
 389	cd->entries = 0;
 390	atomic_set(&cd->writers, 0);
 391	cd->last_close = 0;
 392	cd->last_warn = -1;
 393	list_add(&cd->others, &cache_list);
 394	spin_unlock(&cache_list_lock);
 395
 396	/* start the cleaning process */
 397	queue_delayed_work(system_power_efficient_wq, &cache_cleaner, 0);
 398}
 399EXPORT_SYMBOL_GPL(sunrpc_init_cache_detail);
 400
 401void sunrpc_destroy_cache_detail(struct cache_detail *cd)
 402{
 403	cache_purge(cd);
 404	spin_lock(&cache_list_lock);
 405	spin_lock(&cd->hash_lock);
 
 
 
 
 
 406	if (current_detail == cd)
 407		current_detail = NULL;
 408	list_del_init(&cd->others);
 409	spin_unlock(&cd->hash_lock);
 410	spin_unlock(&cache_list_lock);
 411	if (list_empty(&cache_list)) {
 412		/* module must be being unloaded so its safe to kill the worker */
 413		cancel_delayed_work_sync(&cache_cleaner);
 414	}
 
 
 
 415}
 416EXPORT_SYMBOL_GPL(sunrpc_destroy_cache_detail);
 417
 418/* clean cache tries to find something to clean
 419 * and cleans it.
 420 * It returns 1 if it cleaned something,
 421 *            0 if it didn't find anything this time
 422 *           -1 if it fell off the end of the list.
 423 */
 424static int cache_clean(void)
 425{
 426	int rv = 0;
 427	struct list_head *next;
 428
 429	spin_lock(&cache_list_lock);
 430
 431	/* find a suitable table if we don't already have one */
 432	while (current_detail == NULL ||
 433	    current_index >= current_detail->hash_size) {
 434		if (current_detail)
 435			next = current_detail->others.next;
 436		else
 437			next = cache_list.next;
 438		if (next == &cache_list) {
 439			current_detail = NULL;
 440			spin_unlock(&cache_list_lock);
 441			return -1;
 442		}
 443		current_detail = list_entry(next, struct cache_detail, others);
 444		if (current_detail->nextcheck > seconds_since_boot())
 445			current_index = current_detail->hash_size;
 446		else {
 447			current_index = 0;
 448			current_detail->nextcheck = seconds_since_boot()+30*60;
 449		}
 450	}
 451
 452	/* find a non-empty bucket in the table */
 453	while (current_detail &&
 454	       current_index < current_detail->hash_size &&
 455	       hlist_empty(&current_detail->hash_table[current_index]))
 456		current_index++;
 457
 458	/* find a cleanable entry in the bucket and clean it, or set to next bucket */
 459
 460	if (current_detail && current_index < current_detail->hash_size) {
 461		struct cache_head *ch = NULL;
 462		struct cache_detail *d;
 463		struct hlist_head *head;
 464		struct hlist_node *tmp;
 465
 466		spin_lock(&current_detail->hash_lock);
 467
 468		/* Ok, now to clean this strand */
 469
 470		head = &current_detail->hash_table[current_index];
 471		hlist_for_each_entry_safe(ch, tmp, head, cache_list) {
 472			if (current_detail->nextcheck > ch->expiry_time)
 473				current_detail->nextcheck = ch->expiry_time+1;
 474			if (!cache_is_expired(current_detail, ch))
 475				continue;
 476
 477			sunrpc_begin_cache_remove_entry(ch, current_detail);
 478			trace_cache_entry_expired(current_detail, ch);
 
 479			rv = 1;
 480			break;
 481		}
 482
 483		spin_unlock(&current_detail->hash_lock);
 484		d = current_detail;
 485		if (!ch)
 486			current_index ++;
 487		spin_unlock(&cache_list_lock);
 488		if (ch)
 489			sunrpc_end_cache_remove_entry(ch, d);
 
 
 
 
 490	} else
 491		spin_unlock(&cache_list_lock);
 492
 493	return rv;
 494}
 495
 496/*
 497 * We want to regularly clean the cache, so we need to schedule some work ...
 498 */
 499static void do_cache_clean(struct work_struct *work)
 500{
 501	int delay = 5;
 502	if (cache_clean() == -1)
 503		delay = round_jiffies_relative(30*HZ);
 504
 505	if (list_empty(&cache_list))
 506		delay = 0;
 507
 508	if (delay)
 509		queue_delayed_work(system_power_efficient_wq,
 510				   &cache_cleaner, delay);
 511}
 512
 513
 514/*
 515 * Clean all caches promptly.  This just calls cache_clean
 516 * repeatedly until we are sure that every cache has had a chance to
 517 * be fully cleaned
 518 */
 519void cache_flush(void)
 520{
 521	while (cache_clean() != -1)
 522		cond_resched();
 523	while (cache_clean() != -1)
 524		cond_resched();
 525}
 526EXPORT_SYMBOL_GPL(cache_flush);
 527
 528void cache_purge(struct cache_detail *detail)
 529{
 530	struct cache_head *ch = NULL;
 531	struct hlist_head *head = NULL;
 532	int i = 0;
 533
 534	spin_lock(&detail->hash_lock);
 535	if (!detail->entries) {
 536		spin_unlock(&detail->hash_lock);
 537		return;
 538	}
 539
 540	dprintk("RPC: %d entries in %s cache\n", detail->entries, detail->name);
 541	for (i = 0; i < detail->hash_size; i++) {
 542		head = &detail->hash_table[i];
 543		while (!hlist_empty(head)) {
 544			ch = hlist_entry(head->first, struct cache_head,
 545					 cache_list);
 546			sunrpc_begin_cache_remove_entry(ch, detail);
 547			spin_unlock(&detail->hash_lock);
 548			sunrpc_end_cache_remove_entry(ch, detail);
 549			spin_lock(&detail->hash_lock);
 550		}
 551	}
 552	spin_unlock(&detail->hash_lock);
 553}
 554EXPORT_SYMBOL_GPL(cache_purge);
 555
 556
 557/*
 558 * Deferral and Revisiting of Requests.
 559 *
 560 * If a cache lookup finds a pending entry, we
 561 * need to defer the request and revisit it later.
 562 * All deferred requests are stored in a hash table,
 563 * indexed by "struct cache_head *".
 564 * As it may be wasteful to store a whole request
 565 * structure, we allow the request to provide a
 566 * deferred form, which must contain a
 567 * 'struct cache_deferred_req'
 568 * This cache_deferred_req contains a method to allow
 569 * it to be revisited when cache info is available
 570 */
 571
 572#define	DFR_HASHSIZE	(PAGE_SIZE/sizeof(struct list_head))
 573#define	DFR_HASH(item)	((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE)
 574
 575#define	DFR_MAX	300	/* ??? */
 576
 577static DEFINE_SPINLOCK(cache_defer_lock);
 578static LIST_HEAD(cache_defer_list);
 579static struct hlist_head cache_defer_hash[DFR_HASHSIZE];
 580static int cache_defer_cnt;
 581
 582static void __unhash_deferred_req(struct cache_deferred_req *dreq)
 583{
 584	hlist_del_init(&dreq->hash);
 585	if (!list_empty(&dreq->recent)) {
 586		list_del_init(&dreq->recent);
 587		cache_defer_cnt--;
 588	}
 589}
 590
 591static void __hash_deferred_req(struct cache_deferred_req *dreq, struct cache_head *item)
 592{
 593	int hash = DFR_HASH(item);
 594
 595	INIT_LIST_HEAD(&dreq->recent);
 596	hlist_add_head(&dreq->hash, &cache_defer_hash[hash]);
 597}
 598
 599static void setup_deferral(struct cache_deferred_req *dreq,
 600			   struct cache_head *item,
 601			   int count_me)
 602{
 603
 604	dreq->item = item;
 605
 606	spin_lock(&cache_defer_lock);
 607
 608	__hash_deferred_req(dreq, item);
 609
 610	if (count_me) {
 611		cache_defer_cnt++;
 612		list_add(&dreq->recent, &cache_defer_list);
 613	}
 614
 615	spin_unlock(&cache_defer_lock);
 616
 617}
 618
 619struct thread_deferred_req {
 620	struct cache_deferred_req handle;
 621	struct completion completion;
 622};
 623
 624static void cache_restart_thread(struct cache_deferred_req *dreq, int too_many)
 625{
 626	struct thread_deferred_req *dr =
 627		container_of(dreq, struct thread_deferred_req, handle);
 628	complete(&dr->completion);
 629}
 630
 631static void cache_wait_req(struct cache_req *req, struct cache_head *item)
 632{
 633	struct thread_deferred_req sleeper;
 634	struct cache_deferred_req *dreq = &sleeper.handle;
 635
 636	sleeper.completion = COMPLETION_INITIALIZER_ONSTACK(sleeper.completion);
 637	dreq->revisit = cache_restart_thread;
 638
 639	setup_deferral(dreq, item, 0);
 640
 641	if (!test_bit(CACHE_PENDING, &item->flags) ||
 642	    wait_for_completion_interruptible_timeout(
 643		    &sleeper.completion, req->thread_wait) <= 0) {
 644		/* The completion wasn't completed, so we need
 645		 * to clean up
 646		 */
 647		spin_lock(&cache_defer_lock);
 648		if (!hlist_unhashed(&sleeper.handle.hash)) {
 649			__unhash_deferred_req(&sleeper.handle);
 650			spin_unlock(&cache_defer_lock);
 651		} else {
 652			/* cache_revisit_request already removed
 653			 * this from the hash table, but hasn't
 654			 * called ->revisit yet.  It will very soon
 655			 * and we need to wait for it.
 656			 */
 657			spin_unlock(&cache_defer_lock);
 658			wait_for_completion(&sleeper.completion);
 659		}
 660	}
 661}
 662
 663static void cache_limit_defers(void)
 664{
 665	/* Make sure we haven't exceed the limit of allowed deferred
 666	 * requests.
 667	 */
 668	struct cache_deferred_req *discard = NULL;
 669
 670	if (cache_defer_cnt <= DFR_MAX)
 671		return;
 672
 673	spin_lock(&cache_defer_lock);
 674
 675	/* Consider removing either the first or the last */
 676	if (cache_defer_cnt > DFR_MAX) {
 677		if (prandom_u32() & 1)
 678			discard = list_entry(cache_defer_list.next,
 679					     struct cache_deferred_req, recent);
 680		else
 681			discard = list_entry(cache_defer_list.prev,
 682					     struct cache_deferred_req, recent);
 683		__unhash_deferred_req(discard);
 684	}
 685	spin_unlock(&cache_defer_lock);
 686	if (discard)
 687		discard->revisit(discard, 1);
 688}
 689
 690/* Return true if and only if a deferred request is queued. */
 691static bool cache_defer_req(struct cache_req *req, struct cache_head *item)
 692{
 693	struct cache_deferred_req *dreq;
 694
 695	if (req->thread_wait) {
 696		cache_wait_req(req, item);
 697		if (!test_bit(CACHE_PENDING, &item->flags))
 698			return false;
 699	}
 700	dreq = req->defer(req);
 701	if (dreq == NULL)
 702		return false;
 703	setup_deferral(dreq, item, 1);
 704	if (!test_bit(CACHE_PENDING, &item->flags))
 705		/* Bit could have been cleared before we managed to
 706		 * set up the deferral, so need to revisit just in case
 707		 */
 708		cache_revisit_request(item);
 709
 710	cache_limit_defers();
 711	return true;
 712}
 713
 714static void cache_revisit_request(struct cache_head *item)
 715{
 716	struct cache_deferred_req *dreq;
 717	struct list_head pending;
 718	struct hlist_node *tmp;
 719	int hash = DFR_HASH(item);
 720
 721	INIT_LIST_HEAD(&pending);
 722	spin_lock(&cache_defer_lock);
 723
 724	hlist_for_each_entry_safe(dreq, tmp, &cache_defer_hash[hash], hash)
 725		if (dreq->item == item) {
 726			__unhash_deferred_req(dreq);
 727			list_add(&dreq->recent, &pending);
 728		}
 729
 730	spin_unlock(&cache_defer_lock);
 731
 732	while (!list_empty(&pending)) {
 733		dreq = list_entry(pending.next, struct cache_deferred_req, recent);
 734		list_del_init(&dreq->recent);
 735		dreq->revisit(dreq, 0);
 736	}
 737}
 738
 739void cache_clean_deferred(void *owner)
 740{
 741	struct cache_deferred_req *dreq, *tmp;
 742	struct list_head pending;
 743
 744
 745	INIT_LIST_HEAD(&pending);
 746	spin_lock(&cache_defer_lock);
 747
 748	list_for_each_entry_safe(dreq, tmp, &cache_defer_list, recent) {
 749		if (dreq->owner == owner) {
 750			__unhash_deferred_req(dreq);
 751			list_add(&dreq->recent, &pending);
 752		}
 753	}
 754	spin_unlock(&cache_defer_lock);
 755
 756	while (!list_empty(&pending)) {
 757		dreq = list_entry(pending.next, struct cache_deferred_req, recent);
 758		list_del_init(&dreq->recent);
 759		dreq->revisit(dreq, 1);
 760	}
 761}
 762
 763/*
 764 * communicate with user-space
 765 *
 766 * We have a magic /proc file - /proc/net/rpc/<cachename>/channel.
 767 * On read, you get a full request, or block.
 768 * On write, an update request is processed.
 769 * Poll works if anything to read, and always allows write.
 770 *
 771 * Implemented by linked list of requests.  Each open file has
 772 * a ->private that also exists in this list.  New requests are added
 773 * to the end and may wakeup and preceding readers.
 774 * New readers are added to the head.  If, on read, an item is found with
 775 * CACHE_UPCALLING clear, we free it from the list.
 776 *
 777 */
 778
 779static DEFINE_SPINLOCK(queue_lock);
 780static DEFINE_MUTEX(queue_io_mutex);
 781
 782struct cache_queue {
 783	struct list_head	list;
 784	int			reader;	/* if 0, then request */
 785};
 786struct cache_request {
 787	struct cache_queue	q;
 788	struct cache_head	*item;
 789	char			* buf;
 790	int			len;
 791	int			readers;
 792};
 793struct cache_reader {
 794	struct cache_queue	q;
 795	int			offset;	/* if non-0, we have a refcnt on next request */
 796};
 797
 798static int cache_request(struct cache_detail *detail,
 799			       struct cache_request *crq)
 800{
 801	char *bp = crq->buf;
 802	int len = PAGE_SIZE;
 803
 804	detail->cache_request(detail, crq->item, &bp, &len);
 805	if (len < 0)
 806		return -EAGAIN;
 807	return PAGE_SIZE - len;
 808}
 809
 810static ssize_t cache_read(struct file *filp, char __user *buf, size_t count,
 811			  loff_t *ppos, struct cache_detail *cd)
 812{
 813	struct cache_reader *rp = filp->private_data;
 814	struct cache_request *rq;
 815	struct inode *inode = file_inode(filp);
 816	int err;
 817
 818	if (count == 0)
 819		return 0;
 820
 821	inode_lock(inode); /* protect against multiple concurrent
 822			      * readers on this file */
 823 again:
 824	spin_lock(&queue_lock);
 825	/* need to find next request */
 826	while (rp->q.list.next != &cd->queue &&
 827	       list_entry(rp->q.list.next, struct cache_queue, list)
 828	       ->reader) {
 829		struct list_head *next = rp->q.list.next;
 830		list_move(&rp->q.list, next);
 831	}
 832	if (rp->q.list.next == &cd->queue) {
 833		spin_unlock(&queue_lock);
 834		inode_unlock(inode);
 835		WARN_ON_ONCE(rp->offset);
 836		return 0;
 837	}
 838	rq = container_of(rp->q.list.next, struct cache_request, q.list);
 839	WARN_ON_ONCE(rq->q.reader);
 840	if (rp->offset == 0)
 841		rq->readers++;
 842	spin_unlock(&queue_lock);
 843
 844	if (rq->len == 0) {
 845		err = cache_request(cd, rq);
 846		if (err < 0)
 847			goto out;
 848		rq->len = err;
 849	}
 850
 851	if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) {
 852		err = -EAGAIN;
 853		spin_lock(&queue_lock);
 854		list_move(&rp->q.list, &rq->q.list);
 855		spin_unlock(&queue_lock);
 856	} else {
 857		if (rp->offset + count > rq->len)
 858			count = rq->len - rp->offset;
 859		err = -EFAULT;
 860		if (copy_to_user(buf, rq->buf + rp->offset, count))
 861			goto out;
 862		rp->offset += count;
 863		if (rp->offset >= rq->len) {
 864			rp->offset = 0;
 865			spin_lock(&queue_lock);
 866			list_move(&rp->q.list, &rq->q.list);
 867			spin_unlock(&queue_lock);
 868		}
 869		err = 0;
 870	}
 871 out:
 872	if (rp->offset == 0) {
 873		/* need to release rq */
 874		spin_lock(&queue_lock);
 875		rq->readers--;
 876		if (rq->readers == 0 &&
 877		    !test_bit(CACHE_PENDING, &rq->item->flags)) {
 878			list_del(&rq->q.list);
 879			spin_unlock(&queue_lock);
 880			cache_put(rq->item, cd);
 881			kfree(rq->buf);
 882			kfree(rq);
 883		} else
 884			spin_unlock(&queue_lock);
 885	}
 886	if (err == -EAGAIN)
 887		goto again;
 888	inode_unlock(inode);
 889	return err ? err :  count;
 890}
 891
 892static ssize_t cache_do_downcall(char *kaddr, const char __user *buf,
 893				 size_t count, struct cache_detail *cd)
 894{
 895	ssize_t ret;
 896
 897	if (count == 0)
 898		return -EINVAL;
 899	if (copy_from_user(kaddr, buf, count))
 900		return -EFAULT;
 901	kaddr[count] = '\0';
 902	ret = cd->cache_parse(cd, kaddr, count);
 903	if (!ret)
 904		ret = count;
 905	return ret;
 906}
 907
 908static ssize_t cache_slow_downcall(const char __user *buf,
 909				   size_t count, struct cache_detail *cd)
 910{
 911	static char write_buf[8192]; /* protected by queue_io_mutex */
 912	ssize_t ret = -EINVAL;
 913
 914	if (count >= sizeof(write_buf))
 915		goto out;
 916	mutex_lock(&queue_io_mutex);
 917	ret = cache_do_downcall(write_buf, buf, count, cd);
 918	mutex_unlock(&queue_io_mutex);
 919out:
 920	return ret;
 921}
 922
 923static ssize_t cache_downcall(struct address_space *mapping,
 924			      const char __user *buf,
 925			      size_t count, struct cache_detail *cd)
 926{
 927	struct page *page;
 928	char *kaddr;
 929	ssize_t ret = -ENOMEM;
 930
 931	if (count >= PAGE_SIZE)
 932		goto out_slow;
 933
 934	page = find_or_create_page(mapping, 0, GFP_KERNEL);
 935	if (!page)
 936		goto out_slow;
 937
 938	kaddr = kmap(page);
 939	ret = cache_do_downcall(kaddr, buf, count, cd);
 940	kunmap(page);
 941	unlock_page(page);
 942	put_page(page);
 943	return ret;
 944out_slow:
 945	return cache_slow_downcall(buf, count, cd);
 946}
 947
 948static ssize_t cache_write(struct file *filp, const char __user *buf,
 949			   size_t count, loff_t *ppos,
 950			   struct cache_detail *cd)
 951{
 952	struct address_space *mapping = filp->f_mapping;
 953	struct inode *inode = file_inode(filp);
 954	ssize_t ret = -EINVAL;
 955
 956	if (!cd->cache_parse)
 957		goto out;
 958
 959	inode_lock(inode);
 960	ret = cache_downcall(mapping, buf, count, cd);
 961	inode_unlock(inode);
 962out:
 963	return ret;
 964}
 965
 966static DECLARE_WAIT_QUEUE_HEAD(queue_wait);
 967
 968static __poll_t cache_poll(struct file *filp, poll_table *wait,
 969			       struct cache_detail *cd)
 970{
 971	__poll_t mask;
 972	struct cache_reader *rp = filp->private_data;
 973	struct cache_queue *cq;
 974
 975	poll_wait(filp, &queue_wait, wait);
 976
 977	/* alway allow write */
 978	mask = EPOLLOUT | EPOLLWRNORM;
 979
 980	if (!rp)
 981		return mask;
 982
 983	spin_lock(&queue_lock);
 984
 985	for (cq= &rp->q; &cq->list != &cd->queue;
 986	     cq = list_entry(cq->list.next, struct cache_queue, list))
 987		if (!cq->reader) {
 988			mask |= EPOLLIN | EPOLLRDNORM;
 989			break;
 990		}
 991	spin_unlock(&queue_lock);
 992	return mask;
 993}
 994
 995static int cache_ioctl(struct inode *ino, struct file *filp,
 996		       unsigned int cmd, unsigned long arg,
 997		       struct cache_detail *cd)
 998{
 999	int len = 0;
1000	struct cache_reader *rp = filp->private_data;
1001	struct cache_queue *cq;
1002
1003	if (cmd != FIONREAD || !rp)
1004		return -EINVAL;
1005
1006	spin_lock(&queue_lock);
1007
1008	/* only find the length remaining in current request,
1009	 * or the length of the next request
1010	 */
1011	for (cq= &rp->q; &cq->list != &cd->queue;
1012	     cq = list_entry(cq->list.next, struct cache_queue, list))
1013		if (!cq->reader) {
1014			struct cache_request *cr =
1015				container_of(cq, struct cache_request, q);
1016			len = cr->len - rp->offset;
1017			break;
1018		}
1019	spin_unlock(&queue_lock);
1020
1021	return put_user(len, (int __user *)arg);
1022}
1023
1024static int cache_open(struct inode *inode, struct file *filp,
1025		      struct cache_detail *cd)
1026{
1027	struct cache_reader *rp = NULL;
1028
1029	if (!cd || !try_module_get(cd->owner))
1030		return -EACCES;
1031	nonseekable_open(inode, filp);
1032	if (filp->f_mode & FMODE_READ) {
1033		rp = kmalloc(sizeof(*rp), GFP_KERNEL);
1034		if (!rp) {
1035			module_put(cd->owner);
1036			return -ENOMEM;
1037		}
1038		rp->offset = 0;
1039		rp->q.reader = 1;
1040
1041		spin_lock(&queue_lock);
1042		list_add(&rp->q.list, &cd->queue);
1043		spin_unlock(&queue_lock);
1044	}
1045	if (filp->f_mode & FMODE_WRITE)
1046		atomic_inc(&cd->writers);
1047	filp->private_data = rp;
1048	return 0;
1049}
1050
1051static int cache_release(struct inode *inode, struct file *filp,
1052			 struct cache_detail *cd)
1053{
1054	struct cache_reader *rp = filp->private_data;
1055
1056	if (rp) {
1057		spin_lock(&queue_lock);
1058		if (rp->offset) {
1059			struct cache_queue *cq;
1060			for (cq= &rp->q; &cq->list != &cd->queue;
1061			     cq = list_entry(cq->list.next, struct cache_queue, list))
1062				if (!cq->reader) {
1063					container_of(cq, struct cache_request, q)
1064						->readers--;
1065					break;
1066				}
1067			rp->offset = 0;
1068		}
1069		list_del(&rp->q.list);
1070		spin_unlock(&queue_lock);
1071
1072		filp->private_data = NULL;
1073		kfree(rp);
1074
1075	}
1076	if (filp->f_mode & FMODE_WRITE) {
1077		atomic_dec(&cd->writers);
1078		cd->last_close = seconds_since_boot();
 
1079	}
1080	module_put(cd->owner);
1081	return 0;
1082}
1083
1084
1085
1086static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch)
1087{
1088	struct cache_queue *cq, *tmp;
1089	struct cache_request *cr;
1090	struct list_head dequeued;
1091
1092	INIT_LIST_HEAD(&dequeued);
1093	spin_lock(&queue_lock);
1094	list_for_each_entry_safe(cq, tmp, &detail->queue, list)
1095		if (!cq->reader) {
1096			cr = container_of(cq, struct cache_request, q);
1097			if (cr->item != ch)
1098				continue;
1099			if (test_bit(CACHE_PENDING, &ch->flags))
1100				/* Lost a race and it is pending again */
1101				break;
1102			if (cr->readers != 0)
1103				continue;
1104			list_move(&cr->q.list, &dequeued);
 
 
 
 
 
1105		}
1106	spin_unlock(&queue_lock);
1107	while (!list_empty(&dequeued)) {
1108		cr = list_entry(dequeued.next, struct cache_request, q.list);
1109		list_del(&cr->q.list);
1110		cache_put(cr->item, detail);
1111		kfree(cr->buf);
1112		kfree(cr);
1113	}
1114}
1115
1116/*
1117 * Support routines for text-based upcalls.
1118 * Fields are separated by spaces.
1119 * Fields are either mangled to quote space tab newline slosh with slosh
1120 * or a hexified with a leading \x
1121 * Record is terminated with newline.
1122 *
1123 */
1124
1125void qword_add(char **bpp, int *lp, char *str)
1126{
1127	char *bp = *bpp;
1128	int len = *lp;
1129	int ret;
1130
1131	if (len < 0) return;
1132
1133	ret = string_escape_str(str, bp, len, ESCAPE_OCTAL, "\\ \n\t");
1134	if (ret >= len) {
1135		bp += len;
1136		len = -1;
1137	} else {
1138		bp += ret;
1139		len -= ret;
 
 
 
 
 
 
 
 
 
 
 
 
 
1140		*bp++ = ' ';
1141		len--;
1142	}
1143	*bpp = bp;
1144	*lp = len;
1145}
1146EXPORT_SYMBOL_GPL(qword_add);
1147
1148void qword_addhex(char **bpp, int *lp, char *buf, int blen)
1149{
1150	char *bp = *bpp;
1151	int len = *lp;
1152
1153	if (len < 0) return;
1154
1155	if (len > 2) {
1156		*bp++ = '\\';
1157		*bp++ = 'x';
1158		len -= 2;
1159		while (blen && len >= 2) {
1160			bp = hex_byte_pack(bp, *buf++);
 
 
1161			len -= 2;
1162			blen--;
1163		}
1164	}
1165	if (blen || len<1) len = -1;
1166	else {
1167		*bp++ = ' ';
1168		len--;
1169	}
1170	*bpp = bp;
1171	*lp = len;
1172}
1173EXPORT_SYMBOL_GPL(qword_addhex);
1174
1175static void warn_no_listener(struct cache_detail *detail)
1176{
1177	if (detail->last_warn != detail->last_close) {
1178		detail->last_warn = detail->last_close;
1179		if (detail->warn_no_listener)
1180			detail->warn_no_listener(detail, detail->last_close != 0);
1181	}
1182}
1183
1184static bool cache_listeners_exist(struct cache_detail *detail)
1185{
1186	if (atomic_read(&detail->writers))
1187		return true;
1188	if (detail->last_close == 0)
1189		/* This cache was never opened */
1190		return false;
1191	if (detail->last_close < seconds_since_boot() - 30)
1192		/*
1193		 * We allow for the possibility that someone might
1194		 * restart a userspace daemon without restarting the
1195		 * server; but after 30 seconds, we give up.
1196		 */
1197		 return false;
1198	return true;
1199}
1200
1201/*
1202 * register an upcall request to user-space and queue it up for read() by the
1203 * upcall daemon.
1204 *
1205 * Each request is at most one page long.
1206 */
1207static int cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h)
 
 
 
 
1208{
 
1209	char *buf;
1210	struct cache_request *crq;
1211	int ret = 0;
 
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		trace_cache_entry_upcall(detail, h);
1236	} else
1237		/* Lost a race, no longer PENDING, so don't enqueue */
1238		ret = -EAGAIN;
1239	spin_unlock(&queue_lock);
1240	wake_up(&queue_wait);
1241	if (ret == -EAGAIN) {
1242		kfree(buf);
1243		kfree(crq);
1244	}
1245	return ret;
1246}
1247
1248int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h)
1249{
1250	if (test_and_set_bit(CACHE_PENDING, &h->flags))
1251		return 0;
1252	return cache_pipe_upcall(detail, h);
1253}
1254EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall);
1255
1256int sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
1257				     struct cache_head *h)
1258{
1259	if (!cache_listeners_exist(detail)) {
1260		warn_no_listener(detail);
1261		trace_cache_entry_no_listener(detail, h);
1262		return -EINVAL;
1263	}
1264	return sunrpc_cache_pipe_upcall(detail, h);
1265}
1266EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall_timeout);
1267
1268/*
1269 * parse a message from user-space and pass it
1270 * to an appropriate cache
1271 * Messages are, like requests, separated into fields by
1272 * spaces and dequotes as \xHEXSTRING or embedded \nnn octal
1273 *
1274 * Message is
1275 *   reply cachename expiry key ... content....
1276 *
1277 * key and content are both parsed by cache
1278 */
1279
 
1280int qword_get(char **bpp, char *dest, int bufsize)
1281{
1282	/* return bytes copied, or -1 on error */
1283	char *bp = *bpp;
1284	int len = 0;
1285
1286	while (*bp == ' ') bp++;
1287
1288	if (bp[0] == '\\' && bp[1] == 'x') {
1289		/* HEX STRING */
1290		bp += 2;
1291		while (len < bufsize - 1) {
1292			int h, l;
1293
1294			h = hex_to_bin(bp[0]);
1295			if (h < 0)
1296				break;
1297
1298			l = hex_to_bin(bp[1]);
1299			if (l < 0)
1300				break;
1301
1302			*dest++ = (h << 4) | l;
1303			bp += 2;
1304			len++;
1305		}
1306	} else {
1307		/* text with \nnn octal quoting */
1308		while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) {
1309			if (*bp == '\\' &&
1310			    isodigit(bp[1]) && (bp[1] <= '3') &&
1311			    isodigit(bp[2]) &&
1312			    isodigit(bp[3])) {
1313				int byte = (*++bp -'0');
1314				bp++;
1315				byte = (byte << 3) | (*bp++ - '0');
1316				byte = (byte << 3) | (*bp++ - '0');
1317				*dest++ = byte;
1318				len++;
1319			} else {
1320				*dest++ = *bp++;
1321				len++;
1322			}
1323		}
1324	}
1325
1326	if (*bp != ' ' && *bp != '\n' && *bp != '\0')
1327		return -1;
1328	while (*bp == ' ') bp++;
1329	*bpp = bp;
1330	*dest = '\0';
1331	return len;
1332}
1333EXPORT_SYMBOL_GPL(qword_get);
1334
1335
1336/*
1337 * support /proc/net/rpc/$CACHENAME/content
1338 * as a seqfile.
1339 * We call ->cache_show passing NULL for the item to
1340 * get a header, then pass each real item in the cache
1341 */
1342
1343static void *__cache_seq_start(struct seq_file *m, loff_t *pos)
 
 
 
 
 
1344{
1345	loff_t n = *pos;
1346	unsigned int hash, entry;
1347	struct cache_head *ch;
1348	struct cache_detail *cd = m->private;
 
1349
 
1350	if (!n--)
1351		return SEQ_START_TOKEN;
1352	hash = n >> 32;
1353	entry = n & ((1LL<<32) - 1);
1354
1355	hlist_for_each_entry_rcu(ch, &cd->hash_table[hash], cache_list)
1356		if (!entry--)
1357			return ch;
1358	n &= ~((1LL<<32) - 1);
1359	do {
1360		hash++;
1361		n += 1LL<<32;
1362	} while(hash < cd->hash_size &&
1363		hlist_empty(&cd->hash_table[hash]));
1364	if (hash >= cd->hash_size)
1365		return NULL;
1366	*pos = n+1;
1367	return hlist_entry_safe(rcu_dereference_raw(
1368				hlist_first_rcu(&cd->hash_table[hash])),
1369				struct cache_head, cache_list);
1370}
1371
1372static void *cache_seq_next(struct seq_file *m, void *p, loff_t *pos)
1373{
1374	struct cache_head *ch = p;
1375	int hash = (*pos >> 32);
1376	struct cache_detail *cd = m->private;
1377
1378	if (p == SEQ_START_TOKEN)
1379		hash = 0;
1380	else if (ch->cache_list.next == NULL) {
1381		hash++;
1382		*pos += 1LL<<32;
1383	} else {
1384		++*pos;
1385		return hlist_entry_safe(rcu_dereference_raw(
1386					hlist_next_rcu(&ch->cache_list)),
1387					struct cache_head, cache_list);
1388	}
1389	*pos &= ~((1LL<<32) - 1);
1390	while (hash < cd->hash_size &&
1391	       hlist_empty(&cd->hash_table[hash])) {
1392		hash++;
1393		*pos += 1LL<<32;
1394	}
1395	if (hash >= cd->hash_size)
1396		return NULL;
1397	++*pos;
1398	return hlist_entry_safe(rcu_dereference_raw(
1399				hlist_first_rcu(&cd->hash_table[hash])),
1400				struct cache_head, cache_list);
1401}
1402
1403void *cache_seq_start_rcu(struct seq_file *m, loff_t *pos)
1404	__acquires(RCU)
1405{
1406	rcu_read_lock();
1407	return __cache_seq_start(m, pos);
1408}
1409EXPORT_SYMBOL_GPL(cache_seq_start_rcu);
1410
1411void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos)
1412{
1413	return cache_seq_next(file, p, pos);
1414}
1415EXPORT_SYMBOL_GPL(cache_seq_next_rcu);
1416
1417void cache_seq_stop_rcu(struct seq_file *m, void *p)
1418	__releases(RCU)
1419{
1420	rcu_read_unlock();
1421}
1422EXPORT_SYMBOL_GPL(cache_seq_stop_rcu);
1423
1424static int c_show(struct seq_file *m, void *p)
1425{
1426	struct cache_head *cp = p;
1427	struct cache_detail *cd = m->private;
1428
1429	if (p == SEQ_START_TOKEN)
1430		return cd->cache_show(m, cd, NULL);
1431
1432	ifdebug(CACHE)
1433		seq_printf(m, "# expiry=%lld refcnt=%d flags=%lx\n",
1434			   convert_to_wallclock(cp->expiry_time),
1435			   kref_read(&cp->ref), cp->flags);
1436	cache_get(cp);
1437	if (cache_check(cd, cp, NULL))
1438		/* cache_check does a cache_put on failure */
1439		seq_printf(m, "# ");
1440	else {
1441		if (cache_is_expired(cd, cp))
1442			seq_printf(m, "# ");
1443		cache_put(cp, cd);
1444	}
1445
1446	return cd->cache_show(m, cd, cp);
1447}
1448
1449static const struct seq_operations cache_content_op = {
1450	.start	= cache_seq_start_rcu,
1451	.next	= cache_seq_next_rcu,
1452	.stop	= cache_seq_stop_rcu,
1453	.show	= c_show,
1454};
1455
1456static int content_open(struct inode *inode, struct file *file,
1457			struct cache_detail *cd)
1458{
1459	struct seq_file *seq;
1460	int err;
1461
1462	if (!cd || !try_module_get(cd->owner))
1463		return -EACCES;
1464
1465	err = seq_open(file, &cache_content_op);
1466	if (err) {
1467		module_put(cd->owner);
1468		return err;
1469	}
1470
1471	seq = file->private_data;
1472	seq->private = cd;
1473	return 0;
1474}
1475
1476static int content_release(struct inode *inode, struct file *file,
1477		struct cache_detail *cd)
1478{
1479	int ret = seq_release(inode, file);
1480	module_put(cd->owner);
1481	return ret;
1482}
1483
1484static int open_flush(struct inode *inode, struct file *file,
1485			struct cache_detail *cd)
1486{
1487	if (!cd || !try_module_get(cd->owner))
1488		return -EACCES;
1489	return nonseekable_open(inode, file);
1490}
1491
1492static int release_flush(struct inode *inode, struct file *file,
1493			struct cache_detail *cd)
1494{
1495	module_put(cd->owner);
1496	return 0;
1497}
1498
1499static ssize_t read_flush(struct file *file, char __user *buf,
1500			  size_t count, loff_t *ppos,
1501			  struct cache_detail *cd)
1502{
1503	char tbuf[22];
 
1504	size_t len;
1505
1506	len = snprintf(tbuf, sizeof(tbuf), "%llu\n",
1507			convert_to_wallclock(cd->flush_time));
1508	return simple_read_from_buffer(buf, count, ppos, tbuf, len);
 
 
 
 
 
 
 
 
1509}
1510
1511static ssize_t write_flush(struct file *file, const char __user *buf,
1512			   size_t count, loff_t *ppos,
1513			   struct cache_detail *cd)
1514{
1515	char tbuf[20];
1516	char *ep;
1517	time64_t now;
1518
1519	if (*ppos || count > sizeof(tbuf)-1)
1520		return -EINVAL;
1521	if (copy_from_user(tbuf, buf, count))
1522		return -EFAULT;
1523	tbuf[count] = 0;
1524	simple_strtoul(tbuf, &ep, 0);
1525	if (*ep && *ep != '\n')
1526		return -EINVAL;
1527	/* Note that while we check that 'buf' holds a valid number,
1528	 * we always ignore the value and just flush everything.
1529	 * Making use of the number leads to races.
1530	 */
1531
1532	now = seconds_since_boot();
1533	/* Always flush everything, so behave like cache_purge()
1534	 * Do this by advancing flush_time to the current time,
1535	 * or by one second if it has already reached the current time.
1536	 * Newly added cache entries will always have ->last_refresh greater
1537	 * that ->flush_time, so they don't get flushed prematurely.
1538	 */
1539
1540	if (cd->flush_time >= now)
1541		now = cd->flush_time + 1;
1542
1543	cd->flush_time = now;
1544	cd->nextcheck = now;
1545	cache_flush();
1546
1547	if (cd->flush)
1548		cd->flush();
1549
1550	*ppos += count;
1551	return count;
1552}
1553
1554static ssize_t cache_read_procfs(struct file *filp, char __user *buf,
1555				 size_t count, loff_t *ppos)
1556{
1557	struct cache_detail *cd = PDE_DATA(file_inode(filp));
1558
1559	return cache_read(filp, buf, count, ppos, cd);
1560}
1561
1562static ssize_t cache_write_procfs(struct file *filp, const char __user *buf,
1563				  size_t count, loff_t *ppos)
1564{
1565	struct cache_detail *cd = PDE_DATA(file_inode(filp));
1566
1567	return cache_write(filp, buf, count, ppos, cd);
1568}
1569
1570static __poll_t cache_poll_procfs(struct file *filp, poll_table *wait)
1571{
1572	struct cache_detail *cd = PDE_DATA(file_inode(filp));
1573
1574	return cache_poll(filp, wait, cd);
1575}
1576
1577static long cache_ioctl_procfs(struct file *filp,
1578			       unsigned int cmd, unsigned long arg)
1579{
1580	struct inode *inode = file_inode(filp);
1581	struct cache_detail *cd = PDE_DATA(inode);
1582
1583	return cache_ioctl(inode, filp, cmd, arg, cd);
1584}
1585
1586static int cache_open_procfs(struct inode *inode, struct file *filp)
1587{
1588	struct cache_detail *cd = PDE_DATA(inode);
1589
1590	return cache_open(inode, filp, cd);
1591}
1592
1593static int cache_release_procfs(struct inode *inode, struct file *filp)
1594{
1595	struct cache_detail *cd = PDE_DATA(inode);
1596
1597	return cache_release(inode, filp, cd);
1598}
1599
1600static const struct proc_ops cache_channel_proc_ops = {
1601	.proc_lseek	= no_llseek,
1602	.proc_read	= cache_read_procfs,
1603	.proc_write	= cache_write_procfs,
1604	.proc_poll	= cache_poll_procfs,
1605	.proc_ioctl	= cache_ioctl_procfs, /* for FIONREAD */
1606	.proc_open	= cache_open_procfs,
1607	.proc_release	= cache_release_procfs,
 
1608};
1609
1610static int content_open_procfs(struct inode *inode, struct file *filp)
1611{
1612	struct cache_detail *cd = PDE_DATA(inode);
1613
1614	return content_open(inode, filp, cd);
1615}
1616
1617static int content_release_procfs(struct inode *inode, struct file *filp)
1618{
1619	struct cache_detail *cd = PDE_DATA(inode);
1620
1621	return content_release(inode, filp, cd);
1622}
1623
1624static const struct proc_ops content_proc_ops = {
1625	.proc_open	= content_open_procfs,
1626	.proc_read	= seq_read,
1627	.proc_lseek	= seq_lseek,
1628	.proc_release	= content_release_procfs,
1629};
1630
1631static int open_flush_procfs(struct inode *inode, struct file *filp)
1632{
1633	struct cache_detail *cd = PDE_DATA(inode);
1634
1635	return open_flush(inode, filp, cd);
1636}
1637
1638static int release_flush_procfs(struct inode *inode, struct file *filp)
1639{
1640	struct cache_detail *cd = PDE_DATA(inode);
1641
1642	return release_flush(inode, filp, cd);
1643}
1644
1645static ssize_t read_flush_procfs(struct file *filp, char __user *buf,
1646			    size_t count, loff_t *ppos)
1647{
1648	struct cache_detail *cd = PDE_DATA(file_inode(filp));
1649
1650	return read_flush(filp, buf, count, ppos, cd);
1651}
1652
1653static ssize_t write_flush_procfs(struct file *filp,
1654				  const char __user *buf,
1655				  size_t count, loff_t *ppos)
1656{
1657	struct cache_detail *cd = PDE_DATA(file_inode(filp));
1658
1659	return write_flush(filp, buf, count, ppos, cd);
1660}
1661
1662static const struct proc_ops cache_flush_proc_ops = {
1663	.proc_open	= open_flush_procfs,
1664	.proc_read	= read_flush_procfs,
1665	.proc_write	= write_flush_procfs,
1666	.proc_release	= release_flush_procfs,
1667	.proc_lseek	= no_llseek,
1668};
1669
1670static void remove_cache_proc_entries(struct cache_detail *cd)
1671{
1672	if (cd->procfs) {
1673		proc_remove(cd->procfs);
1674		cd->procfs = NULL;
1675	}
 
 
 
 
 
 
 
 
 
1676}
1677
1678#ifdef CONFIG_PROC_FS
1679static int create_cache_proc_entries(struct cache_detail *cd, struct net *net)
1680{
1681	struct proc_dir_entry *p;
1682	struct sunrpc_net *sn;
1683
1684	sn = net_generic(net, sunrpc_net_id);
1685	cd->procfs = proc_mkdir(cd->name, sn->proc_net_rpc);
1686	if (cd->procfs == NULL)
1687		goto out_nomem;
 
 
1688
1689	p = proc_create_data("flush", S_IFREG | 0600,
1690			     cd->procfs, &cache_flush_proc_ops, cd);
 
 
1691	if (p == NULL)
1692		goto out_nomem;
1693
1694	if (cd->cache_request || cd->cache_parse) {
1695		p = proc_create_data("channel", S_IFREG | 0600, cd->procfs,
1696				     &cache_channel_proc_ops, cd);
 
 
1697		if (p == NULL)
1698			goto out_nomem;
1699	}
1700	if (cd->cache_show) {
1701		p = proc_create_data("content", S_IFREG | 0400, cd->procfs,
1702				     &content_proc_ops, cd);
 
 
1703		if (p == NULL)
1704			goto out_nomem;
1705	}
1706	return 0;
1707out_nomem:
1708	remove_cache_proc_entries(cd);
1709	return -ENOMEM;
1710}
1711#else /* CONFIG_PROC_FS */
1712static int create_cache_proc_entries(struct cache_detail *cd, struct net *net)
1713{
1714	return 0;
1715}
1716#endif
1717
1718void __init cache_initialize(void)
1719{
1720	INIT_DEFERRABLE_WORK(&cache_cleaner, do_cache_clean);
1721}
1722
1723int cache_register_net(struct cache_detail *cd, struct net *net)
1724{
1725	int ret;
1726
1727	sunrpc_init_cache_detail(cd);
1728	ret = create_cache_proc_entries(cd, net);
1729	if (ret)
1730		sunrpc_destroy_cache_detail(cd);
1731	return ret;
1732}
1733EXPORT_SYMBOL_GPL(cache_register_net);
1734
1735void cache_unregister_net(struct cache_detail *cd, struct net *net)
1736{
1737	remove_cache_proc_entries(cd);
1738	sunrpc_destroy_cache_detail(cd);
1739}
1740EXPORT_SYMBOL_GPL(cache_unregister_net);
1741
1742struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net)
1743{
1744	struct cache_detail *cd;
1745	int i;
1746
1747	cd = kmemdup(tmpl, sizeof(struct cache_detail), GFP_KERNEL);
1748	if (cd == NULL)
1749		return ERR_PTR(-ENOMEM);
1750
1751	cd->hash_table = kcalloc(cd->hash_size, sizeof(struct hlist_head),
1752				 GFP_KERNEL);
1753	if (cd->hash_table == NULL) {
1754		kfree(cd);
1755		return ERR_PTR(-ENOMEM);
1756	}
1757
1758	for (i = 0; i < cd->hash_size; i++)
1759		INIT_HLIST_HEAD(&cd->hash_table[i]);
1760	cd->net = net;
1761	return cd;
1762}
1763EXPORT_SYMBOL_GPL(cache_create_net);
1764
1765void cache_destroy_net(struct cache_detail *cd, struct net *net)
1766{
1767	kfree(cd->hash_table);
1768	kfree(cd);
1769}
1770EXPORT_SYMBOL_GPL(cache_destroy_net);
1771
1772static ssize_t cache_read_pipefs(struct file *filp, char __user *buf,
1773				 size_t count, loff_t *ppos)
1774{
1775	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1776
1777	return cache_read(filp, buf, count, ppos, cd);
1778}
1779
1780static ssize_t cache_write_pipefs(struct file *filp, const char __user *buf,
1781				  size_t count, loff_t *ppos)
1782{
1783	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1784
1785	return cache_write(filp, buf, count, ppos, cd);
1786}
1787
1788static __poll_t cache_poll_pipefs(struct file *filp, poll_table *wait)
1789{
1790	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1791
1792	return cache_poll(filp, wait, cd);
1793}
1794
1795static long cache_ioctl_pipefs(struct file *filp,
1796			      unsigned int cmd, unsigned long arg)
1797{
1798	struct inode *inode = file_inode(filp);
1799	struct cache_detail *cd = RPC_I(inode)->private;
1800
1801	return cache_ioctl(inode, filp, cmd, arg, cd);
1802}
1803
1804static int cache_open_pipefs(struct inode *inode, struct file *filp)
1805{
1806	struct cache_detail *cd = RPC_I(inode)->private;
1807
1808	return cache_open(inode, filp, cd);
1809}
1810
1811static int cache_release_pipefs(struct inode *inode, struct file *filp)
1812{
1813	struct cache_detail *cd = RPC_I(inode)->private;
1814
1815	return cache_release(inode, filp, cd);
1816}
1817
1818const struct file_operations cache_file_operations_pipefs = {
1819	.owner		= THIS_MODULE,
1820	.llseek		= no_llseek,
1821	.read		= cache_read_pipefs,
1822	.write		= cache_write_pipefs,
1823	.poll		= cache_poll_pipefs,
1824	.unlocked_ioctl	= cache_ioctl_pipefs, /* for FIONREAD */
1825	.open		= cache_open_pipefs,
1826	.release	= cache_release_pipefs,
1827};
1828
1829static int content_open_pipefs(struct inode *inode, struct file *filp)
1830{
1831	struct cache_detail *cd = RPC_I(inode)->private;
1832
1833	return content_open(inode, filp, cd);
1834}
1835
1836static int content_release_pipefs(struct inode *inode, struct file *filp)
1837{
1838	struct cache_detail *cd = RPC_I(inode)->private;
1839
1840	return content_release(inode, filp, cd);
1841}
1842
1843const struct file_operations content_file_operations_pipefs = {
1844	.open		= content_open_pipefs,
1845	.read		= seq_read,
1846	.llseek		= seq_lseek,
1847	.release	= content_release_pipefs,
1848};
1849
1850static int open_flush_pipefs(struct inode *inode, struct file *filp)
1851{
1852	struct cache_detail *cd = RPC_I(inode)->private;
1853
1854	return open_flush(inode, filp, cd);
1855}
1856
1857static int release_flush_pipefs(struct inode *inode, struct file *filp)
1858{
1859	struct cache_detail *cd = RPC_I(inode)->private;
1860
1861	return release_flush(inode, filp, cd);
1862}
1863
1864static ssize_t read_flush_pipefs(struct file *filp, char __user *buf,
1865			    size_t count, loff_t *ppos)
1866{
1867	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1868
1869	return read_flush(filp, buf, count, ppos, cd);
1870}
1871
1872static ssize_t write_flush_pipefs(struct file *filp,
1873				  const char __user *buf,
1874				  size_t count, loff_t *ppos)
1875{
1876	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
1877
1878	return write_flush(filp, buf, count, ppos, cd);
1879}
1880
1881const struct file_operations cache_flush_operations_pipefs = {
1882	.open		= open_flush_pipefs,
1883	.read		= read_flush_pipefs,
1884	.write		= write_flush_pipefs,
1885	.release	= release_flush_pipefs,
1886	.llseek		= no_llseek,
1887};
1888
1889int sunrpc_cache_register_pipefs(struct dentry *parent,
1890				 const char *name, umode_t umode,
1891				 struct cache_detail *cd)
1892{
1893	struct dentry *dir = rpc_create_cache_dir(parent, name, umode, cd);
1894	if (IS_ERR(dir))
1895		return PTR_ERR(dir);
1896	cd->pipefs = dir;
1897	return 0;
 
 
 
 
 
 
 
 
 
 
 
1898}
1899EXPORT_SYMBOL_GPL(sunrpc_cache_register_pipefs);
1900
1901void sunrpc_cache_unregister_pipefs(struct cache_detail *cd)
1902{
1903	if (cd->pipefs) {
1904		rpc_remove_cache_dir(cd->pipefs);
1905		cd->pipefs = NULL;
1906	}
1907}
1908EXPORT_SYMBOL_GPL(sunrpc_cache_unregister_pipefs);
1909
1910void sunrpc_cache_unhash(struct cache_detail *cd, struct cache_head *h)
1911{
1912	spin_lock(&cd->hash_lock);
1913	if (!hlist_unhashed(&h->cache_list)){
1914		sunrpc_begin_cache_remove_entry(h, cd);
1915		spin_unlock(&cd->hash_lock);
1916		sunrpc_end_cache_remove_entry(h, cd);
1917	} else
1918		spin_unlock(&cd->hash_lock);
1919}
1920EXPORT_SYMBOL_GPL(sunrpc_cache_unhash);