path: root/fs/netfs/fscache_cookie.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* netfs cookie management
 *
 * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * See Documentation/filesystems/caching/netfs-api.rst for more information on
 * the netfs API.
 */

#define FSCACHE_DEBUG_LEVEL COOKIE
#include <linux/module.h>
#include <linux/slab.h>
#include "internal.h"

struct kmem_cache *fscache_cookie_jar;

static void fscache_cookie_lru_timed_out(struct timer_list *timer);
static void fscache_cookie_lru_worker(struct work_struct *work);
static void fscache_cookie_worker(struct work_struct *work);
static void fscache_unhash_cookie(struct fscache_cookie *cookie);
static void fscache_perform_invalidation(struct fscache_cookie *cookie);

#define fscache_cookie_hash_shift 15
static struct hlist_bl_head fscache_cookie_hash[1 << fscache_cookie_hash_shift];
static LIST_HEAD(fscache_cookies);
static DEFINE_RWLOCK(fscache_cookies_lock);
static LIST_HEAD(fscache_cookie_lru);
static DEFINE_SPINLOCK(fscache_cookie_lru_lock);
DEFINE_TIMER(fscache_cookie_lru_timer, fscache_cookie_lru_timed_out);
static DECLARE_WORK(fscache_cookie_lru_work, fscache_cookie_lru_worker);
static const char fscache_cookie_states[FSCACHE_COOKIE_STATE__NR] = "-LCAIFUWRD";
static unsigned int fscache_lru_cookie_timeout = 10 * HZ;

void fscache_print_cookie(struct fscache_cookie *cookie, char prefix)
{
	const u8 *k;

	pr_err("%c-cookie c=%08x [fl=%lx na=%u nA=%u s=%c]\n",
	       prefix,
	       cookie->debug_id,
	       cookie->flags,
	       atomic_read(&cookie->n_active),
	       atomic_read(&cookie->n_accesses),
	       fscache_cookie_states[cookie->state]);
	pr_err("%c-cookie V=%08x [%s]\n",
	       prefix,
	       cookie->volume->debug_id,
	       cookie->volume->key);

	k = (cookie->key_len <= sizeof(cookie->inline_key)) ?
		cookie->inline_key : cookie->key;
	pr_err("%c-key=[%u] '%*phN'\n", prefix, cookie->key_len, cookie->key_len, k);
}

static void fscache_free_cookie(struct fscache_cookie *cookie)
{
	if (WARN_ON_ONCE(!list_empty(&cookie->commit_link))) {
		spin_lock(&fscache_cookie_lru_lock);
		list_del_init(&cookie->commit_link);
		spin_unlock(&fscache_cookie_lru_lock);
		fscache_stat_d(&fscache_n_cookies_lru);
		fscache_stat(&fscache_n_cookies_lru_removed);
	}

	if (WARN_ON_ONCE(test_bit(FSCACHE_COOKIE_IS_HASHED, &cookie->flags))) {
		fscache_print_cookie(cookie, 'F');
		return;
	}

	write_lock(&fscache_cookies_lock);
	list_del(&cookie->proc_link);
	write_unlock(&fscache_cookies_lock);
	if (cookie->aux_len > sizeof(cookie->inline_aux))
		kfree(cookie->aux);
	if (cookie->key_len > sizeof(cookie->inline_key))
		kfree(cookie->key);
	fscache_stat_d(&fscache_n_cookies);
	kmem_cache_free(fscache_cookie_jar, cookie);
}

static void __fscache_queue_cookie(struct fscache_cookie *cookie)
{
	if (!queue_work(fscache_wq, &cookie->work))
		fscache_put_cookie(cookie, fscache_cookie_put_over_queued);
}

static void fscache_queue_cookie(struct fscache_cookie *cookie,
				 enum fscache_cookie_trace where)
{
	fscache_get_cookie(cookie, where);
	__fscache_queue_cookie(cookie);
}

/*
 * Initialise the access gate on a cookie by setting a flag to prevent the
 * state machine from being queued when the access counter transitions to 0.
 * We're only interested in this when we withdraw caching services from the
 * cookie.
 */
static void fscache_init_access_gate(struct fscache_cookie *cookie)
{
	int n_accesses;

	n_accesses = atomic_read(&cookie->n_accesses);
	trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref),
			     n_accesses, fscache_access_cache_pin);
	set_bit(FSCACHE_COOKIE_NO_ACCESS_WAKE, &cookie->flags);
}

/**
 * fscache_end_cookie_access - Unpin a cache at the end of an access.
 * @cookie: A data file cookie
 * @why: An indication of the circumstances of the access for tracing
 *
 * Unpin a cache cookie after we've accessed it and bring a deferred
 * relinquishment or withdrawal state into effect.
 *
 * The @why indicator is provided for tracing purposes.
 */
void fscache_end_cookie_access(struct fscache_cookie *cookie,
			       enum fscache_access_trace why)
{
	int