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/* General filesystem local caching manager
*
* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL CACHE
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/completion.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#define CREATE_TRACE_POINTS
#include "internal.h"
MODULE_DESCRIPTION("FS Cache Manager");
MODULE_AUTHOR("Red Hat, Inc.");
MODULE_LICENSE("GPL");
unsigned fscache_defer_lookup = 1;
module_param_named(defer_lookup, fscache_defer_lookup, uint,
S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(fscache_defer_lookup,
"Defer cookie lookup to background thread");
unsigned fscache_defer_create = 1;
module_param_named(defer_create, fscache_defer_create, uint,
S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(fscache_defer_create,
"Defer cookie creation to background thread");
unsigned fscache_debug;
module_param_named(debug, fscache_debug, uint,
S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(fscache_debug,
"FS-Cache debugging mask");
struct kobject *fscache_root;
struct workqueue_struct *fscache_object_wq;
struct workqueue_struct *fscache_op_wq;
DEFINE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait);
/* these values serve as lower bounds, will be adjusted in fscache_init() */
static unsigned fscache_object_max_active = 4;
static unsigned fscache_op_max_active = 2;
#ifdef CONFIG_SYSCTL
static struct ctl_table_header *fscache_sysctl_header;
static int fscache_max_active_sysctl(struct ctl_table *table, int write,
void __user *buffer,
size_t *lenp, loff_t *ppos)
{
struct workqueue_struct **wqp = table->extra1;
unsigned int *datap = table->data;
int ret;
ret = proc_dointvec(table, write, buffer, lenp, ppos);
if (ret == 0)
workqueue_set_max_active(*wqp, *datap);
return ret;
}
static struct ctl_table fscache_sysctls[] = {
{
.procname = "object_max_active",
.data = &fscache_object_max_active,
.maxlen = sizeof(unsigned),
.mode = 0644,
.proc_handler = fscache_max_active_sysctl,
.extra1 = &fscache_object_wq,
},
{
.procname = "operation_max_active",
.data = &fscache_op_max_active,
.maxlen = sizeof(unsigned),
.mode = 0644,
.proc_handler = fscache_max_active_sysctl,
.extra1 = &fscache_op_wq,
},
{}
};
static struct ctl_table fscache_sysctls_root[] = {
{
.procname = "fscache",
.mode = 0555,
.child = fscache_sysctls,
},
{}
};
#endif
/*
* Mixing scores (in bits) for (7,20):
* Input delta: 1-bit 2-bit
* 1 round: 330.3 9201.6
* 2 rounds: 1246.4 25475.4
* 3 rounds: 1907.1 31295.1
* 4 rounds: 2042.3 31718.6
* Perfect: 2048 31744
* (32*64) (32*31/2 * 64)
*/
#define HASH_MIX(x, y, a) \
( x ^= (a), \
y ^= x, x = rol32(x, 7),\
x += y, y = rol32(y,20),\
y *= 9 )
static inline unsigned int fold_hash(unsigned long x, unsigned long y)
{
/* Use arch-optimized multiply if one exists */
return __hash_32(y ^ __hash_32(x));
}
/*
* Generate a hash. This is derived from full_name_hash(), but we want to be
* sure it is arch independent and that it doesn't change as bits of the
* computed hash value might appear on disk. The caller also guarantees that
* the hashed data will be a series of aligned 32-bit words.
*/
unsigned int fscache_hash(unsigned int salt, unsigned int *data, unsigned int n)
{
unsigned int a, x = 0, y = salt;
for (; n; n--) {
a = *data++;
HASH_MIX(x, y, a);
}
return fold_hash(x, y);
}
/*
* initialise the fs caching module
*/
static int __init fscache_init(void)
{
unsigned int nr_cpus = num_possible_cpus();
unsigned int cpu;
int ret;
fscache_object_max_active =
clamp_val(nr_cpus,
fscache_object_max_active, WQ_UNBOUND_MAX_ACTIVE);
ret = -ENOMEM;
fscache_object_wq = alloc_workqueue("fscache_object", WQ_UNBOUND,
fscache_object_max_active);
if (!fscache_object_wq)
goto error_object_wq;
fscache_op_max_active =
clamp_val(fscache_object_max_active / 2,
fscache_op_max_active, WQ_UNBOUND_MAX_ACTIVE);
ret = -ENOMEM;
fscache_op_wq = alloc_workqueue("fscache_operation", WQ_UNBOUND,
fscache_op_max_active);
if (!fscache_op_wq)
goto error_op_wq;
for_each_possible_cpu(cpu)
init_waitqueue_head(&per_cpu(fscache_object_cong_wait, cpu));
ret = fscache_proc_init();
if (ret < 0)
goto error_proc;
#ifdef CONFIG_SYSCTL
ret = -ENOMEM;
fscache_sysctl_header = register_sysctl_table(fscache_sysctls_root);
if (!fscache_sysctl_header)
goto error_sysctl;
#endif
fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar",
sizeof(struct fscache_cookie),
0, 0, NULL);
if (!fscache_cookie_jar) {
pr_notice("Failed to allocate a cookie jar\n");
ret = -ENOMEM;
goto error_cookie_jar;
}
fscache_root = kobject_create_and_add("fscache", kernel_kobj);
if (!fscache_root)
goto error_kobj;
pr_notice("Loaded\n");
return 0;
error_kobj:
kmem_cache_destroy(fscache_cookie_jar);
error_cookie_jar:
#ifdef CONFIG_SYSCTL
unregister_sysctl_table(fscache_sysctl_header);
error_sysctl:
#endif
fscache_proc_cleanup();
error_proc:
destroy_workqueue(fscache_op_wq);
error_op_wq:
destroy_workqueue(fscache_object_wq);
error_object_wq:
return ret;
}
fs_initcall(fscache_init);
/*
* clean up on module removal
*/
static void __exit fscache_exit(void)
{
_enter("");
kobject_put(fscache_root);
kmem_cache_destroy(fscache_cookie_jar);
#ifdef CONFIG_SYSCTL
unregister_sysctl_table(fscache_sysctl_header);
#endif
fscache_proc_cleanup();
destroy_workqueue(fscache_op_wq);
destroy_workqueue(fscache_object_wq);
pr_notice("Unloaded\n");
}
module_exit(fscache_exit);
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