1/* General filesystem local caching manager
2 *
3 * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#define FSCACHE_DEBUG_LEVEL CACHE
13#include <linux/module.h>
14#include <linux/init.h>
15#include <linux/sched.h>
16#include <linux/completion.h>
17#include <linux/slab.h>
18#include <linux/seq_file.h>
19#include "internal.h"
20
21MODULE_DESCRIPTION("FS Cache Manager");
22MODULE_AUTHOR("Red Hat, Inc.");
23MODULE_LICENSE("GPL");
24
25unsigned fscache_defer_lookup = 1;
26module_param_named(defer_lookup, fscache_defer_lookup, uint,
27		   S_IWUSR | S_IRUGO);
28MODULE_PARM_DESC(fscache_defer_lookup,
29		 "Defer cookie lookup to background thread");
30
31unsigned fscache_defer_create = 1;
32module_param_named(defer_create, fscache_defer_create, uint,
33		   S_IWUSR | S_IRUGO);
34MODULE_PARM_DESC(fscache_defer_create,
35		 "Defer cookie creation to background thread");
36
37unsigned fscache_debug;
38module_param_named(debug, fscache_debug, uint,
39		   S_IWUSR | S_IRUGO);
40MODULE_PARM_DESC(fscache_debug,
41		 "FS-Cache debugging mask");
42
43struct kobject *fscache_root;
44struct workqueue_struct *fscache_object_wq;
45struct workqueue_struct *fscache_op_wq;
46
47DEFINE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait);
48
49/* these values serve as lower bounds, will be adjusted in fscache_init() */
50static unsigned fscache_object_max_active = 4;
51static unsigned fscache_op_max_active = 2;
52
53#ifdef CONFIG_SYSCTL
54static struct ctl_table_header *fscache_sysctl_header;
55
56static int fscache_max_active_sysctl(struct ctl_table *table, int write,
57				     void __user *buffer,
58				     size_t *lenp, loff_t *ppos)
59{
60	struct workqueue_struct **wqp = table->extra1;
61	unsigned int *datap = table->data;
62	int ret;
63
64	ret = proc_dointvec(table, write, buffer, lenp, ppos);
65	if (ret == 0)
66		workqueue_set_max_active(*wqp, *datap);
67	return ret;
68}
69
70static struct ctl_table fscache_sysctls[] = {
71	{
72		.procname	= "object_max_active",
73		.data		= &fscache_object_max_active,
74		.maxlen		= sizeof(unsigned),
75		.mode		= 0644,
76		.proc_handler	= fscache_max_active_sysctl,
77		.extra1		= &fscache_object_wq,
78	},
79	{
80		.procname	= "operation_max_active",
81		.data		= &fscache_op_max_active,
82		.maxlen		= sizeof(unsigned),
83		.mode		= 0644,
84		.proc_handler	= fscache_max_active_sysctl,
85		.extra1		= &fscache_op_wq,
86	},
87	{}
88};
89
90static struct ctl_table fscache_sysctls_root[] = {
91	{
92		.procname	= "fscache",
93		.mode		= 0555,
94		.child		= fscache_sysctls,
95	},
96	{}
97};
98#endif
99
100/*
101 * initialise the fs caching module
102 */
103static int __init fscache_init(void)
104{
105	unsigned int nr_cpus = num_possible_cpus();
106	unsigned int cpu;
107	int ret;
108
109	fscache_object_max_active =
110		clamp_val(nr_cpus,
111			  fscache_object_max_active, WQ_UNBOUND_MAX_ACTIVE);
112
113	ret = -ENOMEM;
114	fscache_object_wq = alloc_workqueue("fscache_object", WQ_UNBOUND,
115					    fscache_object_max_active);
116	if (!fscache_object_wq)
117		goto error_object_wq;
118
119	fscache_op_max_active =
120		clamp_val(fscache_object_max_active / 2,
121			  fscache_op_max_active, WQ_UNBOUND_MAX_ACTIVE);
122
123	ret = -ENOMEM;
124	fscache_op_wq = alloc_workqueue("fscache_operation", WQ_UNBOUND,
125					fscache_op_max_active);
126	if (!fscache_op_wq)
127		goto error_op_wq;
128
129	for_each_possible_cpu(cpu)
130		init_waitqueue_head(&per_cpu(fscache_object_cong_wait, cpu));
131
132	ret = fscache_proc_init();
133	if (ret < 0)
134		goto error_proc;
135
136#ifdef CONFIG_SYSCTL
137	ret = -ENOMEM;
138	fscache_sysctl_header = register_sysctl_table(fscache_sysctls_root);
139	if (!fscache_sysctl_header)
140		goto error_sysctl;
141#endif
142
143	fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar",
144					       sizeof(struct fscache_cookie),
145					       0,
146					       0,
147					       fscache_cookie_init_once);
148	if (!fscache_cookie_jar) {
149		pr_notice("Failed to allocate a cookie jar\n");
150		ret = -ENOMEM;
151		goto error_cookie_jar;
152	}
153
154	fscache_root = kobject_create_and_add("fscache", kernel_kobj);
155	if (!fscache_root)
156		goto error_kobj;
157
158	pr_notice("Loaded\n");
159	return 0;
160
161error_kobj:
162	kmem_cache_destroy(fscache_cookie_jar);
163error_cookie_jar:
164#ifdef CONFIG_SYSCTL
165	unregister_sysctl_table(fscache_sysctl_header);
166error_sysctl:
167#endif
168	fscache_proc_cleanup();
169error_proc:
170	destroy_workqueue(fscache_op_wq);
171error_op_wq:
172	destroy_workqueue(fscache_object_wq);
173error_object_wq:
174	return ret;
175}
176
177fs_initcall(fscache_init);
178
179/*
180 * clean up on module removal
181 */
182static void __exit fscache_exit(void)
183{
184	_enter("");
185
186	kobject_put(fscache_root);
187	kmem_cache_destroy(fscache_cookie_jar);
188#ifdef CONFIG_SYSCTL
189	unregister_sysctl_table(fscache_sysctl_header);
190#endif
191	fscache_proc_cleanup();
192	destroy_workqueue(fscache_op_wq);
193	destroy_workqueue(fscache_object_wq);
194	pr_notice("Unloaded\n");
195}
196
197module_exit(fscache_exit);
198
199/*
200 * wait_on_atomic_t() sleep function for uninterruptible waiting
201 */
202int fscache_wait_atomic_t(atomic_t *p)
203{
204	schedule();
205	return 0;
206}
207