1// SPDX-License-Identifier: GPL-2.0-or-later
  2/* General filesystem local caching manager
  3 *
  4 * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
  5 * Written by David Howells (dhowells@redhat.com)
  6 */
  7
  8#define FSCACHE_DEBUG_LEVEL CACHE
  9#include <linux/module.h>
 10#include <linux/init.h>
 11#include <linux/sched.h>
 12#include <linux/completion.h>
 13#include <linux/slab.h>
 14#include <linux/seq_file.h>
 15#define CREATE_TRACE_POINTS
 16#include "internal.h"
 17
 18MODULE_DESCRIPTION("FS Cache Manager");
 19MODULE_AUTHOR("Red Hat, Inc.");
 20MODULE_LICENSE("GPL");
 21
 22unsigned fscache_defer_lookup = 1;
 23module_param_named(defer_lookup, fscache_defer_lookup, uint,
 24		   S_IWUSR | S_IRUGO);
 25MODULE_PARM_DESC(fscache_defer_lookup,
 26		 "Defer cookie lookup to background thread");
 27
 28unsigned fscache_defer_create = 1;
 29module_param_named(defer_create, fscache_defer_create, uint,
 30		   S_IWUSR | S_IRUGO);
 31MODULE_PARM_DESC(fscache_defer_create,
 32		 "Defer cookie creation to background thread");
 33
 34unsigned fscache_debug;
 35module_param_named(debug, fscache_debug, uint,
 36		   S_IWUSR | S_IRUGO);
 37MODULE_PARM_DESC(fscache_debug,
 38		 "FS-Cache debugging mask");
 39
 40struct kobject *fscache_root;
 41struct workqueue_struct *fscache_object_wq;
 42struct workqueue_struct *fscache_op_wq;
 43
 44DEFINE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait);
 45
 46/* these values serve as lower bounds, will be adjusted in fscache_init() */
 47static unsigned fscache_object_max_active = 4;
 48static unsigned fscache_op_max_active = 2;
 49
 50#ifdef CONFIG_SYSCTL
 51static struct ctl_table_header *fscache_sysctl_header;
 52
 53static int fscache_max_active_sysctl(struct ctl_table *table, int write,
 54				     void *buffer, size_t *lenp, loff_t *ppos)
 55{
 56	struct workqueue_struct **wqp = table->extra1;
 57	unsigned int *datap = table->data;
 58	int ret;
 59
 60	ret = proc_dointvec(table, write, buffer, lenp, ppos);
 61	if (ret == 0)
 62		workqueue_set_max_active(*wqp, *datap);
 63	return ret;
 64}
 65
 66static struct ctl_table fscache_sysctls[] = {
 67	{
 68		.procname	= "object_max_active",
 69		.data		= &fscache_object_max_active,
 70		.maxlen		= sizeof(unsigned),
 71		.mode		= 0644,
 72		.proc_handler	= fscache_max_active_sysctl,
 73		.extra1		= &fscache_object_wq,
 74	},
 75	{
 76		.procname	= "operation_max_active",
 77		.data		= &fscache_op_max_active,
 78		.maxlen		= sizeof(unsigned),
 79		.mode		= 0644,
 80		.proc_handler	= fscache_max_active_sysctl,
 81		.extra1		= &fscache_op_wq,
 82	},
 83	{}
 84};
 85
 86static struct ctl_table fscache_sysctls_root[] = {
 87	{
 88		.procname	= "fscache",
 89		.mode		= 0555,
 90		.child		= fscache_sysctls,
 91	},
 92	{}
 93};
 94#endif
 95
 96/*
 97 * initialise the fs caching module
 98 */
 99static int __init fscache_init(void)
100{
101	unsigned int nr_cpus = num_possible_cpus();
102	unsigned int cpu;
103	int ret;
104
105	fscache_object_max_active =
106		clamp_val(nr_cpus,
107			  fscache_object_max_active, WQ_UNBOUND_MAX_ACTIVE);
108
109	ret = -ENOMEM;
110	fscache_object_wq = alloc_workqueue("fscache_object", WQ_UNBOUND,
111					    fscache_object_max_active);
112	if (!fscache_object_wq)
113		goto error_object_wq;
114
115	fscache_op_max_active =
116		clamp_val(fscache_object_max_active / 2,
117			  fscache_op_max_active, WQ_UNBOUND_MAX_ACTIVE);
118
119	ret = -ENOMEM;
120	fscache_op_wq = alloc_workqueue("fscache_operation", WQ_UNBOUND,
121					fscache_op_max_active);
122	if (!fscache_op_wq)
123		goto error_op_wq;
124
125	for_each_possible_cpu(cpu)
126		init_waitqueue_head(&per_cpu(fscache_object_cong_wait, cpu));
127
128	ret = fscache_proc_init();
129	if (ret < 0)
130		goto error_proc;
131
132#ifdef CONFIG_SYSCTL
133	ret = -ENOMEM;
134	fscache_sysctl_header = register_sysctl_table(fscache_sysctls_root);
135	if (!fscache_sysctl_header)
136		goto error_sysctl;
137#endif
138
139	fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar",
140					       sizeof(struct fscache_cookie),
141					       0, 0, NULL);
142	if (!fscache_cookie_jar) {
143		pr_notice("Failed to allocate a cookie jar\n");
144		ret = -ENOMEM;
145		goto error_cookie_jar;
146	}
147
148	fscache_root = kobject_create_and_add("fscache", kernel_kobj);
149	if (!fscache_root)
150		goto error_kobj;
151
152	pr_notice("Loaded\n");
153	return 0;
154
155error_kobj:
156	kmem_cache_destroy(fscache_cookie_jar);
157error_cookie_jar:
158#ifdef CONFIG_SYSCTL
159	unregister_sysctl_table(fscache_sysctl_header);
160error_sysctl:
161#endif
162	fscache_proc_cleanup();
163error_proc:
164	destroy_workqueue(fscache_op_wq);
165error_op_wq:
166	destroy_workqueue(fscache_object_wq);
167error_object_wq:
168	return ret;
169}
170
171fs_initcall(fscache_init);
172
173/*
174 * clean up on module removal
175 */
176static void __exit fscache_exit(void)
177{
178	_enter("");
179
180	kobject_put(fscache_root);
181	kmem_cache_destroy(fscache_cookie_jar);
182#ifdef CONFIG_SYSCTL
183	unregister_sysctl_table(fscache_sysctl_header);
184#endif
185	fscache_proc_cleanup();
186	destroy_workqueue(fscache_op_wq);
187	destroy_workqueue(fscache_object_wq);
188	pr_notice("Unloaded\n");
189}
190
191module_exit(fscache_exit);