linux/fs/fscache/main.c
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   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#define CREATE_TRACE_POINTS
  20#include "internal.h"
  21
  22MODULE_DESCRIPTION("FS Cache Manager");
  23MODULE_AUTHOR("Red Hat, Inc.");
  24MODULE_LICENSE("GPL");
  25
  26unsigned fscache_defer_lookup = 1;
  27module_param_named(defer_lookup, fscache_defer_lookup, uint,
  28                   S_IWUSR | S_IRUGO);
  29MODULE_PARM_DESC(fscache_defer_lookup,
  30                 "Defer cookie lookup to background thread");
  31
  32unsigned fscache_defer_create = 1;
  33module_param_named(defer_create, fscache_defer_create, uint,
  34                   S_IWUSR | S_IRUGO);
  35MODULE_PARM_DESC(fscache_defer_create,
  36                 "Defer cookie creation to background thread");
  37
  38unsigned fscache_debug;
  39module_param_named(debug, fscache_debug, uint,
  40                   S_IWUSR | S_IRUGO);
  41MODULE_PARM_DESC(fscache_debug,
  42                 "FS-Cache debugging mask");
  43
  44struct kobject *fscache_root;
  45struct workqueue_struct *fscache_object_wq;
  46struct workqueue_struct *fscache_op_wq;
  47
  48DEFINE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait);
  49
  50/* these values serve as lower bounds, will be adjusted in fscache_init() */
  51static unsigned fscache_object_max_active = 4;
  52static unsigned fscache_op_max_active = 2;
  53
  54#ifdef CONFIG_SYSCTL
  55static struct ctl_table_header *fscache_sysctl_header;
  56
  57static int fscache_max_active_sysctl(struct ctl_table *table, int write,
  58                                     void __user *buffer,
  59                                     size_t *lenp, loff_t *ppos)
  60{
  61        struct workqueue_struct **wqp = table->extra1;
  62        unsigned int *datap = table->data;
  63        int ret;
  64
  65        ret = proc_dointvec(table, write, buffer, lenp, ppos);
  66        if (ret == 0)
  67                workqueue_set_max_active(*wqp, *datap);
  68        return ret;
  69}
  70
  71static struct ctl_table fscache_sysctls[] = {
  72        {
  73                .procname       = "object_max_active",
  74                .data           = &fscache_object_max_active,
  75                .maxlen         = sizeof(unsigned),
  76                .mode           = 0644,
  77                .proc_handler   = fscache_max_active_sysctl,
  78                .extra1         = &fscache_object_wq,
  79        },
  80        {
  81                .procname       = "operation_max_active",
  82                .data           = &fscache_op_max_active,
  83                .maxlen         = sizeof(unsigned),
  84                .mode           = 0644,
  85                .proc_handler   = fscache_max_active_sysctl,
  86                .extra1         = &fscache_op_wq,
  87        },
  88        {}
  89};
  90
  91static struct ctl_table fscache_sysctls_root[] = {
  92        {
  93                .procname       = "fscache",
  94                .mode           = 0555,
  95                .child          = fscache_sysctls,
  96        },
  97        {}
  98};
  99#endif
 100
 101/*
 102 * initialise the fs caching module
 103 */
 104static int __init fscache_init(void)
 105{
 106        unsigned int nr_cpus = num_possible_cpus();
 107        unsigned int cpu;
 108        int ret;
 109
 110        fscache_object_max_active =
 111                clamp_val(nr_cpus,
 112                          fscache_object_max_active, WQ_UNBOUND_MAX_ACTIVE);
 113
 114        ret = -ENOMEM;
 115        fscache_object_wq = alloc_workqueue("fscache_object", WQ_UNBOUND,
 116                                            fscache_object_max_active);
 117        if (!fscache_object_wq)
 118                goto error_object_wq;
 119
 120        fscache_op_max_active =
 121                clamp_val(fscache_object_max_active / 2,
 122                          fscache_op_max_active, WQ_UNBOUND_MAX_ACTIVE);
 123
 124        ret = -ENOMEM;
 125        fscache_op_wq = alloc_workqueue("fscache_operation", WQ_UNBOUND,
 126                                        fscache_op_max_active);
 127        if (!fscache_op_wq)
 128                goto error_op_wq;
 129
 130        for_each_possible_cpu(cpu)
 131                init_waitqueue_head(&per_cpu(fscache_object_cong_wait, cpu));
 132
 133        ret = fscache_proc_init();
 134        if (ret < 0)
 135                goto error_proc;
 136
 137#ifdef CONFIG_SYSCTL
 138        ret = -ENOMEM;
 139        fscache_sysctl_header = register_sysctl_table(fscache_sysctls_root);
 140        if (!fscache_sysctl_header)
 141                goto error_sysctl;
 142#endif
 143
 144        fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar",
 145                                               sizeof(struct fscache_cookie),
 146                                               0, 0, NULL);
 147        if (!fscache_cookie_jar) {
 148                pr_notice("Failed to allocate a cookie jar\n");
 149                ret = -ENOMEM;
 150                goto error_cookie_jar;
 151        }
 152
 153        fscache_root = kobject_create_and_add("fscache", kernel_kobj);
 154        if (!fscache_root)
 155                goto error_kobj;
 156
 157        pr_notice("Loaded\n");
 158        return 0;
 159
 160error_kobj:
 161        kmem_cache_destroy(fscache_cookie_jar);
 162error_cookie_jar:
 163#ifdef CONFIG_SYSCTL
 164        unregister_sysctl_table(fscache_sysctl_header);
 165error_sysctl:
 166#endif
 167        fscache_proc_cleanup();
 168error_proc:
 169        destroy_workqueue(fscache_op_wq);
 170error_op_wq:
 171        destroy_workqueue(fscache_object_wq);
 172error_object_wq:
 173        return ret;
 174}
 175
 176fs_initcall(fscache_init);
 177
 178/*
 179 * clean up on module removal
 180 */
 181static void __exit fscache_exit(void)
 182{
 183        _enter("");
 184
 185        kobject_put(fscache_root);
 186        kmem_cache_destroy(fscache_cookie_jar);
 187#ifdef CONFIG_SYSCTL
 188        unregister_sysctl_table(fscache_sysctl_header);
 189#endif
 190        fscache_proc_cleanup();
 191        destroy_workqueue(fscache_op_wq);
 192        destroy_workqueue(fscache_object_wq);
 193        pr_notice("Unloaded\n");
 194}
 195
 196module_exit(fscache_exit);
 197