Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1918 insertions, 0 deletions

diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
new file mode 100644
index 0000000000..95ff747061
--- /dev/null
+++ b/net/sunrpc/cache.c
@@ -0,0 +1,1918 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * net/sunrpc/cache.c
+ *
+ * Generic code for various authentication-related caches
+ * used by sunrpc clients and servers.
+ *
+ * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
+ */
+
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/slab.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kmod.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/ctype.h>
+#include <linux/string_helpers.h>
+#include <linux/uaccess.h>
+#include <linux/poll.h>
+#include <linux/seq_file.h>
+#include <linux/proc_fs.h>
+#include <linux/net.h>
+#include <linux/workqueue.h>
+#include <linux/mutex.h>
+#include <linux/pagemap.h>
+#include <asm/ioctls.h>
+#include <linux/sunrpc/types.h>
+#include <linux/sunrpc/cache.h>
+#include <linux/sunrpc/stats.h>
+#include <linux/sunrpc/rpc_pipe_fs.h>
+#include <trace/events/sunrpc.h>
+
+#include "netns.h"
+#include "fail.h"
+
+#define	 RPCDBG_FACILITY RPCDBG_CACHE
+
+static bool cache_defer_req(struct cache_req *req, struct cache_head *item);
+static void cache_revisit_request(struct cache_head *item);
+
+static void cache_init(struct cache_head *h, struct cache_detail *detail)
+{
+	time64_t now = seconds_since_boot();
+	INIT_HLIST_NODE(&h->cache_list);
+	h->flags = 0;
+	kref_init(&h->ref);
+	h->expiry_time = now + CACHE_NEW_EXPIRY;
+	if (now <= detail->flush_time)
+		/* ensure it isn't already expired */
+		now = detail->flush_time + 1;
+	h->last_refresh = now;
+}
+
+static void cache_fresh_unlocked(struct cache_head *head,
+				struct cache_detail *detail);
+
+static struct cache_head *sunrpc_cache_find_rcu(struct cache_detail *detail,
+						struct cache_head *key,
+						int hash)
+{
+	struct hlist_head *head = &detail->hash_table[hash];
+	struct cache_head *tmp;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(tmp, head, cache_list) {
+		if (!detail->match(tmp, key))
+			continue;
+		if (test_bit(CACHE_VALID, &tmp->flags) &&
+		    cache_is_expired(detail, tmp))
+			continue;
+		tmp = cache_get_rcu(tmp);
+		rcu_read_unlock();
+		return tmp;
+	}
+	rcu_read_unlock();
+	return NULL;
+}
+
+static void sunrpc_begin_cache_remove_entry(struct cache_head *ch,
+					    struct cache_detail *cd)
+{
+	/* Must be called under cd->hash_lock */
+	hlist_del_init_rcu(&ch->cache_list);
+	set_bit(CACHE_CLEANED, &ch->flags);
+	cd->entries --;
+}
+
+static void sunrpc_end_cache_remove_entry(struct cache_head *ch,
+					  struct cache_detail *cd)
+{
+	cache_fresh_unlocked(ch, cd);
+	cache_put(ch, cd);
+}
+
+static struct cache_head *sunrpc_cache_add_entry(struct cache_detail *detail,
+						 struct cache_head *key,
+						 int hash)
+{
+	struct cache_head *new, *tmp, *freeme = NULL;
+	struct hlist_head *head = &detail->hash_table[hash];
+
+	new = detail->alloc();
+	if (!new)
+		return NULL;
+	/* must fully initialise 'new', else
+	 * we might get lose if we need to
+	 * cache_put it soon.
+	 */
+	cache_init(new, detail);
+	detail->init(new, key);
+
+	spin_lock(&detail->hash_lock);
+
+	/* check if entry appeared while we slept */
+	hlist_for_each_entry_rcu(tmp, head, cache_list,
+				 lockdep_is_held(&detail->hash_lock)) {
+		if (!detail->match(tmp, key))
+			continue;
+		if (test_bit(CACHE_VALID, &tmp->flags) &&
+		    cache_is_expired(detail, tmp)) {
+			sunrpc_begin_cache_remove_entry(tmp, detail);
+			trace_cache_entry_expired(detail, tmp);
+			freeme = tmp;
+			break;
+		}
+		cache_get(tmp);
+		spin_unlock(&detail->hash_lock);
+		cache_put(new, detail);
+		return tmp;
+	}
+
+	hlist_add_head_rcu(&new->cache_list, head);
+	detail->entries++;
+	cache_get(new);
+	spin_unlock(&detail->hash_lock);
+
+	if (freeme)
+		sunrpc_end_cache_remove_entry(freeme, detail);
+	return new;
+}
+
+struct cache_head *sunrpc_cache_lookup_rcu(struct cache_detail *detail,
+					   struct cache_head *key, int hash)
+{
+	struct cache_head *ret;
+
+	ret = sunrpc_cache_find_rcu(detail, key, hash);
+	if (ret)
+		return ret;
+	/* Didn't find anything, insert an empty entry */
+	return sunrpc_cache_add_entry(detail, key, hash);
+}
+EXPORT_SYMBOL_GPL(sunrpc_cache_lookup_rcu);
+
+static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch);
+
+static void cache_fresh_locked(struct cache_head *head, time64_t expiry,
+			       struct cache_detail *detail)
+{
+	time64_t now = seconds_since_boot();
+	if (now <= detail->flush_time)
+		/* ensure it isn't immediately treated as expired */
+		now = detail->flush_time + 1;
+	head->expiry_time = expiry;
+	head->last_refresh = now;
+	smp_wmb(); /* paired with smp_rmb() in cache_is_valid() */
+	set_bit(CACHE_VALID, &head->flags);
+}
+
+static void cache_fresh_unlocked(struct cache_head *head,
+				 struct cache_detail *detail)
+{
+	if (test_and_clear_bit(CACHE_PENDING, &head->flags)) {
+		cache_revisit_request(head);
+		cache_dequeue(detail, head);
+	}
+}
+
+static void cache_make_negative(struct cache_detail *detail,
+				struct cache_head *h)
+{
+	set_bit(CACHE_NEGATIVE, &h->flags);
+	trace_cache_entry_make_negative(detail, h);
+}
+
+static void cache_entry_update(struct cache_detail *detail,
+			       struct cache_head *h,
+			       struct cache_head *new)
+{
+	if (!test_bit(CACHE_NEGATIVE, &new->flags)) {
+		detail->update(h, new);
+		trace_cache_entry_update(detail, h);
+	} else {
+		cache_make_negative(detail, h);
+	}
+}
+
+struct cache_head *sunrpc_cache_update(struct cache_detail *detail,
+				       struct cache_head *new, struct cache_head *old, int hash)
+{
+	/* The 'old' entry is to be replaced by 'new'.
+	 * If 'old' is not VALID, we update it directly,
+	 * otherwise we need to replace it
+	 */
+	struct cache_head *tmp;
+
+	if (!test_bit(CACHE_VALID, &old->flags)) {
+		spin_lock(&detail->hash_lock);
+		if (!test_bit(CACHE_VALID, &old->flags)) {
+			cache_entry_update(detail, old, new);
+			cache_fresh_locked(old, new->expiry_time, detail);
+			spin_unlock(&detail->hash_lock);
+			cache_fresh_unlocked(old, detail);
+			return old;
+		}
+		spin_unlock(&detail->hash_lock);
+	}
+	/* We need to insert a new entry */
+	tmp = detail->alloc();
+	if (!tmp) {
+		cache_put(old, detail);
+		return NULL;
+	}
+	cache_init(tmp, detail);
+	detail->init(tmp, old);
+
+	spin_lock(&detail->hash_lock);
+	cache_entry_update(detail, tmp, new);
+	hlist_add_head(&tmp->cache_list, &detail->hash_table[hash]);
+	detail->entries++;
+	cache_get(tmp);
+	cache_fresh_locked(tmp, new->expiry_time, detail);
+	cache_fresh_locked(old, 0, detail);
+	spin_unlock(&detail->hash_lock);
+	cache_fresh_unlocked(tmp, detail);
+	cache_fresh_unlocked(old, detail);
+	cache_put(old, detail);
+	return tmp;
+}
+EXPORT_SYMBOL_GPL(sunrpc_cache_update);
+
+static inline int cache_is_valid(struct cache_head *h)
+{
+	if (!test_bit(CACHE_VALID, &h->flags))
+		return -EAGAIN;
+	else {
+		/* entry is valid */
+		if (test_bit(CACHE_NEGATIVE, &h->flags))
+			return -ENOENT;
+		else {
+			/*
+			 * In combination with write barrier in
+			 * sunrpc_cache_update, ensures that anyone
+			 * using the cache entry after this sees the
+			 * updated contents:
+			 */
+			smp_rmb();
+			return 0;
+		}
+	}
+}
+
+static int try_to_negate_entry(struct cache_detail *detail, struct cache_head *h)
+{
+	int rv;
+
+	spin_lock(&detail->hash_lock);
+	rv = cache_is_valid(h);
+	if (rv == -EAGAIN) {
+		cache_make_negative(detail, h);
+		cache_fresh_locked(h, seconds_since_boot()+CACHE_NEW_EXPIRY,
+				   detail);
+		rv = -ENOENT;
+	}
+	spin_unlock(&detail->hash_lock);
+	cache_fresh_unlocked(h, detail);
+	return rv;
+}
+
+/*
+ * This is the generic cache management routine for all
+ * the authentication caches.
+ * It checks the currency of a cache item and will (later)
+ * initiate an upcall to fill it if needed.
+ *
+ *
+ * Returns 0 if the cache_head can be used, or cache_puts it and returns
+ * -EAGAIN if upcall is pending and request has been queued
+ * -ETIMEDOUT if upcall failed or request could not be queue or
+ *           upcall completed but item is still invalid (implying that
+ *           the cache item has been replaced with a newer one).
+ * -ENOENT if cache entry was negative
+ */
+int cache_check(struct cache_detail *detail,
+		    struct cache_head *h, struct cache_req *rqstp)
+{
+	int rv;
+	time64_t refresh_age, age;
+
+	/* First decide return status as best we can */
+	rv = cache_is_valid(h);
+
+	/* now see if we want to start an upcall */
+	refresh_age = (h->expiry_time - h->last_refresh);
+	age = seconds_since_boot() - h->last_refresh;
+
+	if (rqstp == NULL) {
+		if (rv == -EAGAIN)
+			rv = -ENOENT;
+	} else if (rv == -EAGAIN ||
+		   (h->expiry_time != 0 && age > refresh_age/2)) {
+		dprintk("RPC:       Want update, refage=%lld, age=%lld\n",
+				refresh_age, age);
+		switch (detail->cache_upcall(detail, h)) {
+		case -EINVAL:
+			rv = try_to_negate_entry(detail, h);
+			break;
+		case -EAGAIN:
+			cache_fresh_unlocked(h, detail);
+			break;
+		}
+	}
+
+	if (rv == -EAGAIN) {
+		if (!cache_defer_req(rqstp, h)) {
+			/*
+			 * Request was not deferred; handle it as best
+			 * we can ourselves:
+			 */
+			rv = cache_is_valid(h);
+			if (rv == -EAGAIN)
+				rv = -ETIMEDOUT;
+		}
+	}
+	if (rv)
+		cache_put(h, detail);
+	return rv;
+}
+EXPORT_SYMBOL_GPL(cache_check);
+
+/*
+ * caches need to be periodically cleaned.
+ * For this we maintain a list of cache_detail and
+ * a current pointer into that list and into the table
+ * for that entry.
+ *
+ * Each time cache_clean is called it finds the next non-empty entry
+ * in the current table and walks the list in that entry
+ * looking for entries that can be removed.
+ *
+ * An entry gets removed if:
+ * - The expiry is before current time
+ * - The last_refresh time is before the flush_time for that cache
+ *
+ * later we might drop old entries with non-NEVER expiry if that table
+ * is getting 'full' for some definition of 'full'
+ *
+ * The question of "how often to scan a table" is an interesting one
+ * and is answered in part by the use of the "nextcheck" field in the
+ * cache_detail.
+ * When a scan of a table begins, the nextcheck field is set to a time
+ * that is well into the future.
+ * While scanning, if an expiry time is found that is earlier than the
+ * current nextcheck time, nextcheck is set to that expiry time.
+ * If the flush_time is ever set to a time earlier than the nextcheck
+ * time, the nextcheck time is then set to that flush_time.
+ *
+ * A table is then only scanned if the current time is at least
+ * the nextcheck time.
+ *
+ */
+
+static LIST_HEAD(cache_list);
+static DEFINE_SPINLOCK(cache_list_lock);
+static struct cache_detail *current_detail;
+static int current_index;
+
+static void do_cache_clean(struct work_struct *work);
+static struct delayed_work cache_cleaner;
+
+void sunrpc_init_cache_detail(struct cache_detail *cd)
+{
+	spin_lock_init(&cd->hash_lock);
+	INIT_LIST_HEAD(&cd->queue);
+	spin_lock(&cache_list_lock);
+	cd->nextcheck = 0;
+	cd->entries = 0;
+	atomic_set(&cd->writers, 0);
+	cd->last_close = 0;
+	cd->last_warn = -1;
+	list_add(&cd->others, &cache_list);
+	spin_unlock(&cache_list_lock);
+
+	/* start the cleaning process */
+	queue_delayed_work(system_power_efficient_wq, &cache_cleaner, 0);
+}
+EXPORT_SYMBOL_GPL(sunrpc_init_cache_detail);
+
+void sunrpc_destroy_cache_detail(struct cache_detail *cd)
+{
+	cache_purge(cd);
+	spin_lock(&cache_list_lock);
+	spin_lock(&cd->hash_lock);
+	if (current_detail == cd)
+		current_detail = NULL;
+	list_del_init(&cd->others);
+	spin_unlock(&cd->hash_lock);
+	spin_unlock(&cache_list_lock);
+	if (list_empty(&cache_list)) {
+		/* module must be being unloaded so its safe to kill the worker */
+		cancel_delayed_work_sync(&cache_cleaner);
+	}
+}
+EXPORT_SYMBOL_GPL(sunrpc_destroy_cache_detail);
+
+/* clean cache tries to find something to clean
+ * and cleans it.
+ * It returns 1 if it cleaned something,
+ *            0 if it didn't find anything this time
+ *           -1 if it fell off the end of the list.
+ */
+static int cache_clean(void)
+{
+	int rv = 0;
+	struct list_head *next;
+
+	spin_lock(&cache_list_lock);
+
+	/* find a suitable table if we don't already have one */
+	while (current_detail == NULL ||
+	    current_index >= current_detail->hash_size) {
+		if (current_detail)
+			next = current_detail->others.next;
+		else
+			next = cache_list.next;
+		if (next == &cache_list) {
+			current_detail = NULL;
+			spin_unlock(&cache_list_lock);
+			return -1;
+		}
+		current_detail = list_entry(next, struct cache_detail, others);
+		if (current_detail->nextcheck > seconds_since_boot())
+			current_index = current_detail->hash_size;
+		else {
+			current_index = 0;
+			current_detail->nextcheck = seconds_since_boot()+30*60;
+		}
+	}
+
+	/* find a non-empty bucket in the table */
+	while (current_detail &&
+	       current_index < current_detail->hash_size &&
+	       hlist_empty(&current_detail->hash_table[current_index]))
+		current_index++;
+
+	/* find a cleanable entry in the bucket and clean it, or set to next bucket */
+
+	if (current_detail && current_index < current_detail->hash_size) {
+		struct cache_head *ch = NULL;
+		struct cache_detail *d;
+		struct hlist_head *head;
+		struct hlist_node *tmp;
+
+		spin_lock(&current_detail->hash_lock);
+
+		/* Ok, now to clean this strand */
+
+		head = &current_detail->hash_table[current_index];
+		hlist_for_each_entry_safe(ch, tmp, head, cache_list) {
+			if (current_detail->nextcheck > ch->expiry_time)
+				current_detail->nextcheck = ch->expiry_time+1;
+			if (!cache_is_expired(current_detail, ch))
+				continue;
+
+			sunrpc_begin_cache_remove_entry(ch, current_detail);
+			trace_cache_entry_expired(current_detail, ch);
+			rv = 1;
+			break;
+		}
+
+		spin_unlock(&current_detail->hash_lock);
+		d = current_detail;
+		if (!ch)
+			current_index ++;
+		spin_unlock(&cache_list_lock);
+		if (ch)
+			sunrpc_end_cache_remove_entry(ch, d);
+	} else
+		spin_unlock(&cache_list_lock);
+
+	return rv;
+}
+
+/*
+ * We want to regularly clean the cache, so we need to schedule some work ...
+ */
+static void do_cache_clean(struct work_struct *work)
+{
+	int delay;
+
+	if (list_empty(&cache_list))
+		return;
+
+	if (cache_clean() == -1)
+		delay = round_jiffies_relative(30*HZ);
+	else
+		delay = 5;
+
+	queue_delayed_work(system_power_efficient_wq, &cache_cleaner, delay);
+}
+
+
+/*
+ * Clean all caches promptly.  This just calls cache_clean
+ * repeatedly until we are sure that every cache has had a chance to
+ * be fully cleaned
+ */
+void cache_flush(void)
+{
+	while (cache_clean() != -1)
+		cond_resched();
+	while (cache_clean() != -1)
+		cond_resched();
+}
+EXPORT_SYMBOL_GPL(cache_flush);
+
+void cache_purge(struct cache_detail *detail)
+{
+	struct cache_head *ch = NULL;
+	struct hlist_head *head = NULL;
+	int i = 0;
+
+	spin_lock(&detail->hash_lock);
+	if (!detail->entries) {
+		spin_unlock(&detail->hash_lock);
+		return;
+	}
+
+	dprintk("RPC: %d entries in %s cache\n", detail->entries, detail->name);
+	for (i = 0; i < detail->hash_size; i++) {
+		head = &detail->hash_table[i];
+		while (!hlist_empty(head)) {
+			ch = hlist_entry(head->first, struct cache_head,
+					 cache_list);
+			sunrpc_begin_cache_remove_entry(ch, detail);
+			spin_unlock(&detail->hash_lock);
+			sunrpc_end_cache_remove_entry(ch, detail);
+			spin_lock(&detail->hash_lock);
+		}
+	}
+	spin_unlock(&detail->hash_lock);
+}
+EXPORT_SYMBOL_GPL(cache_purge);
+
+
+/*
+ * Deferral and Revisiting of Requests.
+ *
+ * If a cache lookup finds a pending entry, we
+ * need to defer the request and revisit it later.
+ * All deferred requests are stored in a hash table,
+ * indexed by "struct cache_head *".
+ * As it may be wasteful to store a whole request
+ * structure, we allow the request to provide a
+ * deferred form, which must contain a
+ * 'struct cache_deferred_req'
+ * This cache_deferred_req contains a method to allow
+ * it to be revisited when cache info is available
+ */
+
+#define	DFR_HASHSIZE	(PAGE_SIZE/sizeof(struct list_head))
+#define	DFR_HASH(item)	((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE)
+
+#define	DFR_MAX	300	/* ??? */
+
+static DEFINE_SPINLOCK(cache_defer_lock);
+static LIST_HEAD(cache_defer_list);
+static struct hlist_head cache_defer_hash[DFR_HASHSIZE];
+static int cache_defer_cnt;
+
+static void __unhash_deferred_req(struct cache_deferred_req *dreq)
+{
+	hlist_del_init(&dreq->hash);
+	if (!list_empty(&dreq->recent)) {
+		list_del_init(&dreq->recent);
+		cache_defer_cnt--;
+	}
+}
+
+static void __hash_deferred_req(struct cache_deferred_req *dreq, struct cache_head *item)
+{
+	int hash = DFR_HASH(item);
+
+	INIT_LIST_HEAD(&dreq->recent);
+	hlist_add_head(&dreq->hash, &cache_defer_hash[hash]);
+}
+
+static void setup_deferral(struct cache_deferred_req *dreq,
+			   struct cache_head *item,
+			   int count_me)
+{
+
+	dreq->item = item;
+
+	spin_lock(&cache_defer_lock);
+
+	__hash_deferred_req(dreq, item);
+
+	if (count_me) {
+		cache_defer_cnt++;
+		list_add(&dreq->recent, &cache_defer_list);
+	}
+
+	spin_unlock(&cache_defer_lock);
+
+}
+
+struct thread_deferred_req {
+	struct cache_deferred_req handle;
+	struct completion completion;
+};
+
+static void cache_restart_thread(struct cache_deferred_req *dreq, int too_many)
+{
+	struct thread_deferred_req *dr =
+		container_of(dreq, struct thread_deferred_req, handle);
+	complete(&dr->completion);
+}
+
+static void cache_wait_req(struct cache_req *req, struct cache_head *item)
+{
+	struct thread_deferred_req sleeper;
+	struct cache_deferred_req *dreq = &sleeper.handle;
+
+	sleeper.completion = COMPLETION_INITIALIZER_ONSTACK(sleeper.completion);
+	dreq->revisit = cache_restart_thread;
+
+	setup_deferral(dreq, item, 0);
+
+	if (!test_bit(CACHE_PENDING, &item->flags) ||
+	    wait_for_completion_interruptible_timeout(
+		    &sleeper.completion, req->thread_wait) <= 0) {
+		/* The completion wasn't completed, so we need
+		 * to clean up
+		 */
+		spin_lock(&cache_defer_lock);
+		if (!hlist_unhashed(&sleeper.handle.hash)) {
+			__unhash_deferred_req(&sleeper.handle);
+			spin_unlock(&cache_defer_lock);
+		} else {
+			/* cache_revisit_request already removed
+			 * this from the hash table, but hasn't
+			 * called ->revisit yet.  It will very soon
+			 * and we need to wait for it.
+			 */
+			spin_unlock(&cache_defer_lock);
+			wait_for_completion(&sleeper.completion);
+		}
+	}
+}
+
+static void cache_limit_defers(void)
+{
+	/* Make sure we haven't exceed the limit of allowed deferred
+	 * requests.
+	 */
+	struct cache_deferred_req *discard = NULL;
+
+	if (cache_defer_cnt <= DFR_MAX)
+		return;
+
+	spin_lock(&cache_defer_lock);
+
+	/* Consider removing either the first or the last */
+	if (cache_defer_cnt > DFR_MAX) {
+		if (get_random_u32_below(2))
+			discard = list_entry(cache_defer_list.next,
+					     struct cache_deferred_req, recent);
+		else
+			discard = list_entry(cache_defer_list.prev,
+					     struct cache_deferred_req, recent);
+		__unhash_deferred_req(discard);
+	}
+	spin_unlock(&cache_defer_lock);
+	if (discard)
+		discard->revisit(discard, 1);
+}
+
+#if IS_ENABLED(CONFIG_FAIL_SUNRPC)
+static inline bool cache_defer_immediately(void)
+{
+	return !fail_sunrpc.ignore_cache_wait &&
+		should_fail(&fail_sunrpc.attr, 1);
+}
+#else
+static inline bool cache_defer_immediately(void)
+{
+	return false;
+}
+#endif
+
+/* Return true if and only if a deferred request is queued. */
+static bool cache_defer_req(struct cache_req *req, struct cache_head *item)
+{
+	struct cache_deferred_req *dreq;
+
+	if (!cache_defer_immediately()) {
+		cache_wait_req(req, item);
+		if (!test_bit(CACHE_PENDING, &item->flags))
+			return false;
+	}
+
+	dreq = req->defer(req);
+	if (dreq == NULL)
+		return false;
+	setup_deferral(dreq, item, 1);
+	if (!test_bit(CACHE_PENDING, &item->flags))
+		/* Bit could have been cleared before we managed to
+		 * set up the deferral, so need to revisit just in case
+		 */
+		cache_revisit_request(item);
+
+	cache_limit_defers();
+	return true;
+}
+
+static void cache_revisit_request(struct cache_head *item)
+{
+	struct cache_deferred_req *dreq;
+	struct list_head pending;
+	struct hlist_node *tmp;
+	int hash = DFR_HASH(item);
+
+	INIT_LIST_HEAD(&pending);
+	spin_lock(&cache_defer_lock);
+
+	hlist_for_each_entry_safe(dreq, tmp, &cache_defer_hash[hash], hash)
+		if (dreq->item == item) {
+			__unhash_deferred_req(dreq);
+			list_add(&dreq->recent, &pending);
+		}
+
+	spin_unlock(&cache_defer_lock);
+
+	while (!list_empty(&pending)) {
+		dreq = list_entry(pending.next, struct cache_deferred_req, recent);
+		list_del_init(&dreq->recent);
+		dreq->revisit(dreq, 0);
+	}
+}
+
+void cache_clean_deferred(void *owner)
+{
+	struct cache_deferred_req *dreq, *tmp;
+	struct list_head pending;
+
+
+	INIT_LIST_HEAD(&pending);
+	spin_lock(&cache_defer_lock);
+
+	list_for_each_entry_safe(dreq, tmp, &cache_defer_list, recent) {
+		if (dreq->owner == owner) {
+			__unhash_deferred_req(dreq);
+			list_add(&dreq->recent, &pending);
+		}
+	}
+	spin_unlock(&cache_defer_lock);
+
+	while (!list_empty(&pending)) {
+		dreq = list_entry(pending.next, struct cache_deferred_req, recent);
+		list_del_init(&dreq->recent);
+		dreq->revisit(dreq, 1);
+	}
+}
+
+/*
+ * communicate with user-space
+ *
+ * We have a magic /proc file - /proc/net/rpc/<cachename>/channel.
+ * On read, you get a full request, or block.
+ * On write, an update request is processed.
+ * Poll works if anything to read, and always allows write.
+ *
+ * Implemented by linked list of requests.  Each open file has
+ * a ->private that also exists in this list.  New requests are added
+ * to the end and may wakeup and preceding readers.
+ * New readers are added to the head.  If, on read, an item is found with
+ * CACHE_UPCALLING clear, we free it from the list.
+ *
+ */
+
+static DEFINE_SPINLOCK(queue_lock);
+
+struct cache_queue {
+	struct list_head	list;
+	int			reader;	/* if 0, then request */
+};
+struct cache_request {
+	struct cache_queue	q;
+	struct cache_head	*item;
+	char			* buf;
+	int			len;
+	int			readers;
+};
+struct cache_reader {
+	struct cache_queue	q;
+	int			offset;	/* if non-0, we have a refcnt on next request */
+};
+
+static int cache_request(struct cache_detail *detail,
+			       struct cache_request *crq)
+{
+	char *bp = crq->buf;
+	int len = PAGE_SIZE;
+
+	detail->cache_request(detail, crq->item, &bp, &len);
+	if (len < 0)
+		return -E2BIG;
+	return PAGE_SIZE - len;
+}
+
+static ssize_t cache_read(struct file *filp, char __user *buf, size_t count,
+			  loff_t *ppos, struct cache_detail *cd)
+{
+	struct cache_reader *rp = filp->private_data;
+	struct cache_request *rq;
+	struct inode *inode = file_inode(filp);
+	int err;
+
+	if (count == 0)
+		return 0;
+
+	inode_lock(inode); /* protect against multiple concurrent
+			      * readers on this file */
+ again:
+	spin_lock(&queue_lock);
+	/* need to find next request */
+	while (rp->q.list.next != &cd->queue &&
+	       list_entry(rp->q.list.next, struct cache_queue, list)
+	       ->reader) {
+		struct list_head *next = rp->q.list.next;
+		list_move(&rp->q.list, next);
+	}
+	if (rp->q.list.next == &cd->queue) {
+		spin_unlock(&queue_lock);
+		inode_unlock(inode);
+		WARN_ON_ONCE(rp->offset);
+		return 0;
+	}
+	rq = container_of(rp->q.list.next, struct cache_request, q.list);
+	WARN_ON_ONCE(rq->q.reader);
+	if (rp->offset == 0)
+		rq->readers++;
+	spin_unlock(&queue_lock);
+
+	if (rq->len == 0) {
+		err = cache_request(cd, rq);
+		if (err < 0)
+			goto out;
+		rq->len = err;
+	}
+
+	if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) {
+		err = -EAGAIN;
+		spin_lock(&queue_lock);
+		list_move(&rp->q.list, &rq->q.list);
+		spin_unlock(&queue_lock);
+	} else {
+		if (rp->offset + count > rq->len)
+			count = rq->len - rp->offset;
+		err = -EFAULT;
+		if (copy_to_user(buf, rq->buf + rp->offset, count))
+			goto out;
+		rp->offset += count;
+		if (rp->offset >= rq->len) {
+			rp->offset = 0;
+			spin_lock(&queue_lock);
+			list_move(&rp->q.list, &rq->q.list);
+			spin_unlock(&queue_lock);
+		}
+		err = 0;
+	}
+ out:
+	if (rp->offset == 0) {
+		/* need to release rq */
+		spin_lock(&queue_lock);
+		rq->readers--;
+		if (rq->readers == 0 &&
+		    !test_bit(CACHE_PENDING, &rq->item->flags)) {
+			list_del(&rq->q.list);
+			spin_unlock(&queue_lock);
+			cache_put(rq->item, cd);
+			kfree(rq->buf);
+			kfree(rq);
+		} else
+			spin_unlock(&queue_lock);
+	}
+	if (err == -EAGAIN)
+		goto again;
+	inode_unlock(inode);
+	return err ? err :  count;
+}
+
+static ssize_t cache_do_downcall(char *kaddr, const char __user *buf,
+				 size_t count, struct cache_detail *cd)
+{
+	ssize_t ret;
+
+	if (count == 0)
+		return -EINVAL;
+	if (copy_from_user(kaddr, buf, count))
+		return -EFAULT;
+	kaddr[count] = '\0';
+	ret = cd->cache_parse(cd, kaddr, count);
+	if (!ret)
+		ret = count;
+	return ret;
+}
+
+static ssize_t cache_downcall(struct address_space *mapping,
+			      const char __user *buf,
+			      size_t count, struct cache_detail *cd)
+{
+	char *write_buf;
+	ssize_t ret = -ENOMEM;
+
+	if (count >= 32768) { /* 32k is max userland buffer, lets check anyway */
+		ret = -EINVAL;
+		goto out;
+	}
+
+	write_buf = kvmalloc(count + 1, GFP_KERNEL);
+	if (!write_buf)
+		goto out;
+
+	ret = cache_do_downcall(write_buf, buf, count, cd);
+	kvfree(write_buf);
+out:
+	return ret;
+}
+
+static ssize_t cache_write(struct file *filp, const char __user *buf,
+			   size_t count, loff_t *ppos,
+			   struct cache_detail *cd)
+{
+	struct address_space *mapping = filp->f_mapping;
+	struct inode *inode = file_inode(filp);
+	ssize_t ret = -EINVAL;
+
+	if (!cd->cache_parse)
+		goto out;
+
+	inode_lock(inode);
+	ret = cache_downcall(mapping, buf, count, cd);
+	inode_unlock(inode);
+out:
+	return ret;
+}
+
+static DECLARE_WAIT_QUEUE_HEAD(queue_wait);
+
+static __poll_t cache_poll(struct file *filp, poll_table *wait,
+			       struct cache_detail *cd)
+{
+	__poll_t mask;
+	struct cache_reader *rp = filp->private_data;
+	struct cache_queue *cq;
+
+	poll_wait(filp, &queue_wait, wait);
+
+	/* alway allow write */
+	mask = EPOLLOUT | EPOLLWRNORM;
+
+	if (!rp)
+		return mask;
+
+	spin_lock(&queue_lock);
+
+	for (cq= &rp->q; &cq->list != &cd->queue;
+	     cq = list_entry(cq->list.next, struct cache_queue, list))
+		if (!cq->reader) {
+			mask |= EPOLLIN | EPOLLRDNORM;
+			break;
+		}
+	spin_unlock(&queue_lock);
+	return mask;
+}
+
+static int cache_ioctl(struct inode *ino, struct file *filp,
+		       unsigned int cmd, unsigned long arg,
+		       struct cache_detail *cd)
+{
+	int len = 0;
+	struct cache_reader *rp = filp->private_data;
+	struct cache_queue *cq;
+
+	if (cmd != FIONREAD || !rp)
+		return -EINVAL;
+
+	spin_lock(&queue_lock);
+
+	/* only find the length remaining in current request,
+	 * or the length of the next request
+	 */
+	for (cq= &rp->q; &cq->list != &cd->queue;
+	     cq = list_entry(cq->list.next, struct cache_queue, list))
+		if (!cq->reader) {
+			struct cache_request *cr =
+				container_of(cq, struct cache_request, q);
+			len = cr->len - rp->offset;
+			break;
+		}
+	spin_unlock(&queue_lock);
+
+	return put_user(len, (int __user *)arg);
+}
+
+static int cache_open(struct inode *inode, struct file *filp,
+		      struct cache_detail *cd)
+{
+	struct cache_reader *rp = NULL;
+
+	if (!cd || !try_module_get(cd->owner))
+		return -EACCES;
+	nonseekable_open(inode, filp);
+	if (filp->f_mode & FMODE_READ) {
+		rp = kmalloc(sizeof(*rp), GFP_KERNEL);
+		if (!rp) {
+			module_put(cd->owner);
+			return -ENOMEM;
+		}
+		rp->offset = 0;
+		rp->q.reader = 1;
+
+		spin_lock(&queue_lock);
+		list_add(&rp->q.list, &cd->queue);
+		spin_unlock(&queue_lock);
+	}
+	if (filp->f_mode & FMODE_WRITE)
+		atomic_inc(&cd->writers);
+	filp->private_data = rp;
+	return 0;
+}
+
+static int cache_release(struct inode *inode, struct file *filp,
+			 struct cache_detail *cd)
+{
+	struct cache_reader *rp = filp->private_data;
+
+	if (rp) {
+		spin_lock(&queue_lock);
+		if (rp->offset) {
+			struct cache_queue *cq;
+			for (cq= &rp->q; &cq->list != &cd->queue;
+			     cq = list_entry(cq->list.next, struct cache_queue, list))
+				if (!cq->reader) {
+					container_of(cq, struct cache_request, q)
+						->readers--;
+					break;
+				}
+			rp->offset = 0;
+		}
+		list_del(&rp->q.list);
+		spin_unlock(&queue_lock);
+
+		filp->private_data = NULL;
+		kfree(rp);
+
+	}
+	if (filp->f_mode & FMODE_WRITE) {
+		atomic_dec(&cd->writers);
+		cd->last_close = seconds_since_boot();
+	}
+	module_put(cd->owner);
+	return 0;
+}
+
+
+
+static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch)
+{
+	struct cache_queue *cq, *tmp;
+	struct cache_request *cr;
+	struct list_head dequeued;
+
+	INIT_LIST_HEAD(&dequeued);
+	spin_lock(&queue_lock);
+	list_for_each_entry_safe(cq, tmp, &detail->queue, list)
+		if (!cq->reader) {
+			cr = container_of(cq, struct cache_request, q);
+			if (cr->item != ch)
+				continue;
+			if (test_bit(CACHE_PENDING, &ch->flags))
+				/* Lost a race and it is pending again */
+				break;
+			if (cr->readers != 0)
+				continue;
+			list_move(&cr->q.list, &dequeued);
+		}
+	spin_unlock(&queue_lock);
+	while (!list_empty(&dequeued)) {
+		cr = list_entry(dequeued.next, struct cache_request, q.list);
+		list_del(&cr->q.list);
+		cache_put(cr->item, detail);
+		kfree(cr->buf);
+		kfree(cr);
+	}
+}
+
+/*
+ * Support routines for text-based upcalls.
+ * Fields are separated by spaces.
+ * Fields are either mangled to quote space tab newline slosh with slosh
+ * or a hexified with a leading \x
+ * Record is terminated with newline.
+ *
+ */
+
+void qword_add(char **bpp, int *lp, char *str)
+{
+	char *bp = *bpp;
+	int len = *lp;
+	int ret;
+
+	if (len < 0) return;
+
+	ret = string_escape_str(str, bp, len, ESCAPE_OCTAL, "\\ \n\t");
+	if (ret >= len) {
+		bp += len;
+		len = -1;
+	} else {
+		bp += ret;
+		len -= ret;
+		*bp++ = ' ';
+		len--;
+	}
+	*bpp = bp;
+	*lp = len;
+}
+EXPORT_SYMBOL_GPL(qword_add);
+
+void qword_addhex(char **bpp, int *lp, char *buf, int blen)
+{
+	char *bp = *bpp;
+	int len = *lp;
+
+	if (len < 0) return;
+
+	if (len > 2) {
+		*bp++ = '\\';
+		*bp++ = 'x';
+		len -= 2;
+		while (blen && len >= 2) {
+			bp = hex_byte_pack(bp, *buf++);
+			len -= 2;
+			blen--;
+		}
+	}
+	if (blen || len<1) len = -1;
+	else {
+		*bp++ = ' ';
+		len--;
+	}
+	*bpp = bp;
+	*lp = len;
+}
+EXPORT_SYMBOL_GPL(qword_addhex);
+
+static void warn_no_listener(struct cache_detail *detail)
+{
+	if (detail->last_warn != detail->last_close) {
+		detail->last_warn = detail->last_close;
+		if (detail->warn_no_listener)
+			detail->warn_no_listener(detail, detail->last_close != 0);
+	}
+}
+
+static bool cache_listeners_exist(struct cache_detail *detail)
+{
+	if (atomic_read(&detail->writers))
+		return true;
+	if (detail->last_close == 0)
+		/* This cache was never opened */
+		return false;
+	if (detail->last_close < seconds_since_boot() - 30)
+		/*
+		 * We allow for the possibility that someone might
+		 * restart a userspace daemon without restarting the
+		 * server; but after 30 seconds, we give up.
+		 */
+		 return false;
+	return true;
+}
+
+/*
+ * register an upcall request to user-space and queue it up for read() by the
+ * upcall daemon.
+ *
+ * Each request is at most one page long.
+ */
+static int cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h)
+{
+	char *buf;
+	struct cache_request *crq;
+	int ret = 0;
+
+	if (test_bit(CACHE_CLEANED, &h->flags))
+		/* Too late to make an upcall */
+		return -EAGAIN;
+
+	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -EAGAIN;
+
+	crq = kmalloc(sizeof (*crq), GFP_KERNEL);
+	if (!crq) {
+		kfree(buf);
+		return -EAGAIN;
+	}
+
+	crq->q.reader = 0;
+	crq->buf = buf;
+	crq->len = 0;
+	crq->readers = 0;
+	spin_lock(&queue_lock);
+	if (test_bit(CACHE_PENDING, &h->flags)) {
+		crq->item = cache_get(h);
+		list_add_tail(&crq->q.list, &detail->queue);
+		trace_cache_entry_upcall(detail, h);
+	} else
+		/* Lost a race, no longer PENDING, so don't enqueue */
+		ret = -EAGAIN;
+	spin_unlock(&queue_lock);
+	wake_up(&queue_wait);
+	if (ret == -EAGAIN) {
+		kfree(buf);
+		kfree(crq);
+	}
+	return ret;
+}
+
+int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h)
+{
+	if (test_and_set_bit(CACHE_PENDING, &h->flags))
+		return 0;
+	return cache_pipe_upcall(detail, h);
+}
+EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall);
+
+int sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
+				     struct cache_head *h)
+{
+	if (!cache_listeners_exist(detail)) {
+		warn_no_listener(detail);
+		trace_cache_entry_no_listener(detail, h);
+		return -EINVAL;
+	}
+	return sunrpc_cache_pipe_upcall(detail, h);
+}
+EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall_timeout);
+
+/*
+ * parse a message from user-space and pass it
+ * to an appropriate cache
+ * Messages are, like requests, separated into fields by
+ * spaces and dequotes as \xHEXSTRING or embedded \nnn octal
+ *
+ * Message is
+ *   reply cachename expiry key ... content....
+ *
+ * key and content are both parsed by cache
+ */
+
+int qword_get(char **bpp, char *dest, int bufsize)
+{
+	/* return bytes copied, or -1 on error */
+	char *bp = *bpp;
+	int len = 0;
+
+	while (*bp == ' ') bp++;
+
+	if (bp[0] == '\\' && bp[1] == 'x') {
+		/* HEX STRING */
+		bp += 2;
+		while (len < bufsize - 1) {
+			int h, l;
+
+			h = hex_to_bin(bp[0]);
+			if (h < 0)
+				break;
+
+			l = hex_to_bin(bp[1]);
+			if (l < 0)
+				break;
+
+			*dest++ = (h << 4) | l;
+			bp += 2;
+			len++;
+		}
+	} else {
+		/* text with \nnn octal quoting */
+		while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) {
+			if (*bp == '\\' &&
+			    isodigit(bp[1]) && (bp[1] <= '3') &&
+			    isodigit(bp[2]) &&
+			    isodigit(bp[3])) {
+				int byte = (*++bp -'0');
+				bp++;
+				byte = (byte << 3) | (*bp++ - '0');
+				byte = (byte << 3) | (*bp++ - '0');
+				*dest++ = byte;
+				len++;
+			} else {
+				*dest++ = *bp++;
+				len++;
+			}
+		}
+	}
+
+	if (*bp != ' ' && *bp != '\n' && *bp != '\0')
+		return -1;
+	while (*bp == ' ') bp++;
+	*bpp = bp;
+	*dest = '\0';
+	return len;
+}
+EXPORT_SYMBOL_GPL(qword_get);
+
+
+/*
+ * support /proc/net/rpc/$CACHENAME/content
+ * as a seqfile.
+ * We call ->cache_show passing NULL for the item to
+ * get a header, then pass each real item in the cache
+ */
+
+static void *__cache_seq_start(struct seq_file *m, loff_t *pos)
+{
+	loff_t n = *pos;
+	unsigned int hash, entry;
+	struct cache_head *ch;
+	struct cache_detail *cd = m->private;
+
+	if (!n--)
+		return SEQ_START_TOKEN;
+	hash = n >> 32;
+	entry = n & ((1LL<<32) - 1);
+
+	hlist_for_each_entry_rcu(ch, &cd->hash_table[hash], cache_list)
+		if (!entry--)
+			return ch;
+	n &= ~((1LL<<32) - 1);
+	do {
+		hash++;
+		n += 1LL<<32;
+	} while(hash < cd->hash_size &&
+		hlist_empty(&cd->hash_table[hash]));
+	if (hash >= cd->hash_size)
+		return NULL;
+	*pos = n+1;
+	return hlist_entry_safe(rcu_dereference_raw(
+				hlist_first_rcu(&cd->hash_table[hash])),
+				struct cache_head, cache_list);
+}
+
+static void *cache_seq_next(struct seq_file *m, void *p, loff_t *pos)
+{
+	struct cache_head *ch = p;
+	int hash = (*pos >> 32);
+	struct cache_detail *cd = m->private;
+
+	if (p == SEQ_START_TOKEN)
+		hash = 0;
+	else if (ch->cache_list.next == NULL) {
+		hash++;
+		*pos += 1LL<<32;
+	} else {
+		++*pos;
+		return hlist_entry_safe(rcu_dereference_raw(
+					hlist_next_rcu(&ch->cache_list)),
+					struct cache_head, cache_list);
+	}
+	*pos &= ~((1LL<<32) - 1);
+	while (hash < cd->hash_size &&
+	       hlist_empty(&cd->hash_table[hash])) {
+		hash++;
+		*pos += 1LL<<32;
+	}
+	if (hash >= cd->hash_size)
+		return NULL;
+	++*pos;
+	return hlist_entry_safe(rcu_dereference_raw(
+				hlist_first_rcu(&cd->hash_table[hash])),
+				struct cache_head, cache_list);
+}
+
+void *cache_seq_start_rcu(struct seq_file *m, loff_t *pos)
+	__acquires(RCU)
+{
+	rcu_read_lock();
+	return __cache_seq_start(m, pos);
+}
+EXPORT_SYMBOL_GPL(cache_seq_start_rcu);
+
+void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos)
+{
+	return cache_seq_next(file, p, pos);
+}
+EXPORT_SYMBOL_GPL(cache_seq_next_rcu);
+
+void cache_seq_stop_rcu(struct seq_file *m, void *p)
+	__releases(RCU)
+{
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(cache_seq_stop_rcu);
+
+static int c_show(struct seq_file *m, void *p)
+{
+	struct cache_head *cp = p;
+	struct cache_detail *cd = m->private;
+
+	if (p == SEQ_START_TOKEN)
+		return cd->cache_show(m, cd, NULL);
+
+	ifdebug(CACHE)
+		seq_printf(m, "# expiry=%lld refcnt=%d flags=%lx\n",
+			   convert_to_wallclock(cp->expiry_time),
+			   kref_read(&cp->ref), cp->flags);
+	cache_get(cp);
+	if (cache_check(cd, cp, NULL))
+		/* cache_check does a cache_put on failure */
+		seq_puts(m, "# ");
+	else {
+		if (cache_is_expired(cd, cp))
+			seq_puts(m, "# ");
+		cache_put(cp, cd);
+	}
+
+	return cd->cache_show(m, cd, cp);
+}
+
+static const struct seq_operations cache_content_op = {
+	.start	= cache_seq_start_rcu,
+	.next	= cache_seq_next_rcu,
+	.stop	= cache_seq_stop_rcu,
+	.show	= c_show,
+};
+
+static int content_open(struct inode *inode, struct file *file,
+			struct cache_detail *cd)
+{
+	struct seq_file *seq;
+	int err;
+
+	if (!cd || !try_module_get(cd->owner))
+		return -EACCES;
+
+	err = seq_open(file, &cache_content_op);
+	if (err) {
+		module_put(cd->owner);
+		return err;
+	}
+
+	seq = file->private_data;
+	seq->private = cd;
+	return 0;
+}
+
+static int content_release(struct inode *inode, struct file *file,
+		struct cache_detail *cd)
+{
+	int ret = seq_release(inode, file);
+	module_put(cd->owner);
+	return ret;
+}
+
+static int open_flush(struct inode *inode, struct file *file,
+			struct cache_detail *cd)
+{
+	if (!cd || !try_module_get(cd->owner))
+		return -EACCES;
+	return nonseekable_open(inode, file);
+}
+
+static int release_flush(struct inode *inode, struct file *file,
+			struct cache_detail *cd)
+{
+	module_put(cd->owner);
+	return 0;
+}
+
+static ssize_t read_flush(struct file *file, char __user *buf,
+			  size_t count, loff_t *ppos,
+			  struct cache_detail *cd)
+{
+	char tbuf[22];
+	size_t len;
+
+	len = snprintf(tbuf, sizeof(tbuf), "%llu\n",
+			convert_to_wallclock(cd->flush_time));
+	return simple_read_from_buffer(buf, count, ppos, tbuf, len);
+}
+
+static ssize_t write_flush(struct file *file, const char __user *buf,
+			   size_t count, loff_t *ppos,
+			   struct cache_detail *cd)
+{
+	char tbuf[20];
+	char *ep;
+	time64_t now;
+
+	if (*ppos || count > sizeof(tbuf)-1)
+		return -EINVAL;
+	if (copy_from_user(tbuf, buf, count))
+		return -EFAULT;
+	tbuf[count] = 0;
+	simple_strtoul(tbuf, &ep, 0);
+	if (*ep && *ep != '\n')
+		return -EINVAL;
+	/* Note that while we check that 'buf' holds a valid number,
+	 * we always ignore the value and just flush everything.
+	 * Making use of the number leads to races.
+	 */
+
+	now = seconds_since_boot();
+	/* Always flush everything, so behave like cache_purge()
+	 * Do this by advancing flush_time to the current time,
+	 * or by one second if it has already reached the current time.
+	 * Newly added cache entries will always have ->last_refresh greater
+	 * that ->flush_time, so they don't get flushed prematurely.
+	 */
+
+	if (cd->flush_time >= now)
+		now = cd->flush_time + 1;
+
+	cd->flush_time = now;
+	cd->nextcheck = now;
+	cache_flush();
+
+	if (cd->flush)
+		cd->flush();
+
+	*ppos += count;
+	return count;
+}
+
+static ssize_t cache_read_procfs(struct file *filp, char __user *buf,
+				 size_t count, loff_t *ppos)
+{
+	struct cache_detail *cd = pde_data(file_inode(filp));
+
+	return cache_read(filp, buf, count, ppos, cd);
+}
+
+static ssize_t cache_write_procfs(struct file *filp, const char __user *buf,
+				  size_t count, loff_t *ppos)
+{
+	struct cache_detail *cd = pde_data(file_inode(filp));
+
+	return cache_write(filp, buf, count, ppos, cd);
+}
+
+static __poll_t cache_poll_procfs(struct file *filp, poll_table *wait)
+{
+	struct cache_detail *cd = pde_data(file_inode(filp));
+
+	return cache_poll(filp, wait, cd);
+}
+
+static long cache_ioctl_procfs(struct file *filp,
+			       unsigned int cmd, unsigned long arg)
+{
+	struct inode *inode = file_inode(filp);
+	struct cache_detail *cd = pde_data(inode);
+
+	return cache_ioctl(inode, filp, cmd, arg, cd);
+}
+
+static int cache_open_procfs(struct inode *inode, struct file *filp)
+{
+	struct cache_detail *cd = pde_data(inode);
+
+	return cache_open(inode, filp, cd);
+}
+
+static int cache_release_procfs(struct inode *inode, struct file *filp)
+{
+	struct cache_detail *cd = pde_data(inode);
+
+	return cache_release(inode, filp, cd);
+}
+
+static const struct proc_ops cache_channel_proc_ops = {
+	.proc_lseek	= no_llseek,
+	.proc_read	= cache_read_procfs,
+	.proc_write	= cache_write_procfs,
+	.proc_poll	= cache_poll_procfs,
+	.proc_ioctl	= cache_ioctl_procfs, /* for FIONREAD */
+	.proc_open	= cache_open_procfs,
+	.proc_release	= cache_release_procfs,
+};
+
+static int content_open_procfs(struct inode *inode, struct file *filp)
+{
+	struct cache_detail *cd = pde_data(inode);
+
+	return content_open(inode, filp, cd);
+}
+
+static int content_release_procfs(struct inode *inode, struct file *filp)
+{
+	struct cache_detail *cd = pde_data(inode);
+
+	return content_release(inode, filp, cd);
+}
+
+static const struct proc_ops content_proc_ops = {
+	.proc_open	= content_open_procfs,
+	.proc_read	= seq_read,
+	.proc_lseek	= seq_lseek,
+	.proc_release	= content_release_procfs,
+};
+
+static int open_flush_procfs(struct inode *inode, struct file *filp)
+{
+	struct cache_detail *cd = pde_data(inode);
+
+	return open_flush(inode, filp, cd);
+}
+
+static int release_flush_procfs(struct inode *inode, struct file *filp)
+{
+	struct cache_detail *cd = pde_data(inode);
+
+	return release_flush(inode, filp, cd);
+}
+
+static ssize_t read_flush_procfs(struct file *filp, char __user *buf,
+			    size_t count, loff_t *ppos)
+{
+	struct cache_detail *cd = pde_data(file_inode(filp));
+
+	return read_flush(filp, buf, count, ppos, cd);
+}
+
+static ssize_t write_flush_procfs(struct file *filp,
+				  const char __user *buf,
+				  size_t count, loff_t *ppos)
+{
+	struct cache_detail *cd = pde_data(file_inode(filp));
+
+	return write_flush(filp, buf, count, ppos, cd);
+}
+
+static const struct proc_ops cache_flush_proc_ops = {
+	.proc_open	= open_flush_procfs,
+	.proc_read	= read_flush_procfs,
+	.proc_write	= write_flush_procfs,
+	.proc_release	= release_flush_procfs,
+	.proc_lseek	= no_llseek,
+};
+
+static void remove_cache_proc_entries(struct cache_detail *cd)
+{
+	if (cd->procfs) {
+		proc_remove(cd->procfs);
+		cd->procfs = NULL;
+	}
+}
+
+#ifdef CONFIG_PROC_FS
+static int create_cache_proc_entries(struct cache_detail *cd, struct net *net)
+{
+	struct proc_dir_entry *p;
+	struct sunrpc_net *sn;
+
+	sn = net_generic(net, sunrpc_net_id);
+	cd->procfs = proc_mkdir(cd->name, sn->proc_net_rpc);
+	if (cd->procfs == NULL)
+		goto out_nomem;
+
+	p = proc_create_data("flush", S_IFREG | 0600,
+			     cd->procfs, &cache_flush_proc_ops, cd);
+	if (p == NULL)
+		goto out_nomem;
+
+	if (cd->cache_request || cd->cache_parse) {
+		p = proc_create_data("channel", S_IFREG | 0600, cd->procfs,
+				     &cache_channel_proc_ops, cd);
+		if (p == NULL)
+			goto out_nomem;
+	}
+	if (cd->cache_show) {
+		p = proc_create_data("content", S_IFREG | 0400, cd->procfs,
+				     &content_proc_ops, cd);
+		if (p == NULL)
+			goto out_nomem;
+	}
+	return 0;
+out_nomem:
+	remove_cache_proc_entries(cd);
+	return -ENOMEM;
+}
+#else /* CONFIG_PROC_FS */
+static int create_cache_proc_entries(struct cache_detail *cd, struct net *net)
+{
+	return 0;
+}
+#endif
+
+void __init cache_initialize(void)
+{
+	INIT_DEFERRABLE_WORK(&cache_cleaner, do_cache_clean);
+}
+
+int cache_register_net(struct cache_detail *cd, struct net *net)
+{
+	int ret;
+
+	sunrpc_init_cache_detail(cd);
+	ret = create_cache_proc_entries(cd, net);
+	if (ret)
+		sunrpc_destroy_cache_detail(cd);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cache_register_net);
+
+void cache_unregister_net(struct cache_detail *cd, struct net *net)
+{
+	remove_cache_proc_entries(cd);
+	sunrpc_destroy_cache_detail(cd);
+}
+EXPORT_SYMBOL_GPL(cache_unregister_net);
+
+struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net)
+{
+	struct cache_detail *cd;
+	int i;
+
+	cd = kmemdup(tmpl, sizeof(struct cache_detail), GFP_KERNEL);
+	if (cd == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	cd->hash_table = kcalloc(cd->hash_size, sizeof(struct hlist_head),
+				 GFP_KERNEL);
+	if (cd->hash_table == NULL) {
+		kfree(cd);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	for (i = 0; i < cd->hash_size; i++)
+		INIT_HLIST_HEAD(&cd->hash_table[i]);
+	cd->net = net;
+	return cd;
+}
+EXPORT_SYMBOL_GPL(cache_create_net);
+
+void cache_destroy_net(struct cache_detail *cd, struct net *net)
+{
+	kfree(cd->hash_table);
+	kfree(cd);
+}
+EXPORT_SYMBOL_GPL(cache_destroy_net);
+
+static ssize_t cache_read_pipefs(struct file *filp, char __user *buf,
+				 size_t count, loff_t *ppos)
+{
+	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
+
+	return cache_read(filp, buf, count, ppos, cd);
+}
+
+static ssize_t cache_write_pipefs(struct file *filp, const char __user *buf,
+				  size_t count, loff_t *ppos)
+{
+	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
+
+	return cache_write(filp, buf, count, ppos, cd);
+}
+
+static __poll_t cache_poll_pipefs(struct file *filp, poll_table *wait)
+{
+	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
+
+	return cache_poll(filp, wait, cd);
+}
+
+static long cache_ioctl_pipefs(struct file *filp,
+			      unsigned int cmd, unsigned long arg)
+{
+	struct inode *inode = file_inode(filp);
+	struct cache_detail *cd = RPC_I(inode)->private;
+
+	return cache_ioctl(inode, filp, cmd, arg, cd);
+}
+
+static int cache_open_pipefs(struct inode *inode, struct file *filp)
+{
+	struct cache_detail *cd = RPC_I(inode)->private;
+
+	return cache_open(inode, filp, cd);
+}
+
+static int cache_release_pipefs(struct inode *inode, struct file *filp)
+{
+	struct cache_detail *cd = RPC_I(inode)->private;
+
+	return cache_release(inode, filp, cd);
+}
+
+const struct file_operations cache_file_operations_pipefs = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.read		= cache_read_pipefs,
+	.write		= cache_write_pipefs,
+	.poll		= cache_poll_pipefs,
+	.unlocked_ioctl	= cache_ioctl_pipefs, /* for FIONREAD */
+	.open		= cache_open_pipefs,
+	.release	= cache_release_pipefs,
+};
+
+static int content_open_pipefs(struct inode *inode, struct file *filp)
+{
+	struct cache_detail *cd = RPC_I(inode)->private;
+
+	return content_open(inode, filp, cd);
+}
+
+static int content_release_pipefs(struct inode *inode, struct file *filp)
+{
+	struct cache_detail *cd = RPC_I(inode)->private;
+
+	return content_release(inode, filp, cd);
+}
+
+const struct file_operations content_file_operations_pipefs = {
+	.open		= content_open_pipefs,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= content_release_pipefs,
+};
+
+static int open_flush_pipefs(struct inode *inode, struct file *filp)
+{
+	struct cache_detail *cd = RPC_I(inode)->private;
+
+	return open_flush(inode, filp, cd);
+}
+
+static int release_flush_pipefs(struct inode *inode, struct file *filp)
+{
+	struct cache_detail *cd = RPC_I(inode)->private;
+
+	return release_flush(inode, filp, cd);
+}
+
+static ssize_t read_flush_pipefs(struct file *filp, char __user *buf,
+			    size_t count, loff_t *ppos)
+{
+	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
+
+	return read_flush(filp, buf, count, ppos, cd);
+}
+
+static ssize_t write_flush_pipefs(struct file *filp,
+				  const char __user *buf,
+				  size_t count, loff_t *ppos)
+{
+	struct cache_detail *cd = RPC_I(file_inode(filp))->private;
+
+	return write_flush(filp, buf, count, ppos, cd);
+}
+
+const struct file_operations cache_flush_operations_pipefs = {
+	.open		= open_flush_pipefs,
+	.read		= read_flush_pipefs,
+	.write		= write_flush_pipefs,
+	.release	= release_flush_pipefs,
+	.llseek		= no_llseek,
+};
+
+int sunrpc_cache_register_pipefs(struct dentry *parent,
+				 const char *name, umode_t umode,
+				 struct cache_detail *cd)
+{
+	struct dentry *dir = rpc_create_cache_dir(parent, name, umode, cd);
+	if (IS_ERR(dir))
+		return PTR_ERR(dir);
+	cd->pipefs = dir;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(sunrpc_cache_register_pipefs);
+
+void sunrpc_cache_unregister_pipefs(struct cache_detail *cd)
+{
+	if (cd->pipefs) {
+		rpc_remove_cache_dir(cd->pipefs);
+		cd->pipefs = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(sunrpc_cache_unregister_pipefs);
+
+void sunrpc_cache_unhash(struct cache_detail *cd, struct cache_head *h)
+{
+	spin_lock(&cd->hash_lock);
+	if (!hlist_unhashed(&h->cache_list)){
+		sunrpc_begin_cache_remove_entry(h, cd);
+		spin_unlock(&cd->hash_lock);
+		sunrpc_end_cache_remove_entry(h, cd);
+	} else
+		spin_unlock(&cd->hash_lock);
+}
+EXPORT_SYMBOL_GPL(sunrpc_cache_unhash);