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#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
  70ctl_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
  90ctl_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                printk(KERN_NOTICE
 150                       "FS-Cache: Failed to allocate a cookie jar\n");
 151                ret = -ENOMEM;
 152                goto error_cookie_jar;
 153        }
 154
 155        fscache_root = kobject_create_and_add("fscache", kernel_kobj);
 156        if (!fscache_root)
 157                goto error_kobj;
 158
 159        printk(KERN_NOTICE "FS-Cache: Loaded\n");
 160        return 0;
 161
 162error_kobj:
 163        kmem_cache_destroy(fscache_cookie_jar);
 164error_cookie_jar:
 165#ifdef CONFIG_SYSCTL
 166        unregister_sysctl_table(fscache_sysctl_header);
 167error_sysctl:
 168#endif
 169        fscache_proc_cleanup();
 170error_proc:
 171        destroy_workqueue(fscache_op_wq);
 172error_op_wq:
 173        destroy_workqueue(fscache_object_wq);
 174error_object_wq:
 175        return ret;
 176}
 177
 178fs_initcall(fscache_init);
 179
 180/*
 181 * clean up on module removal
 182 */
 183static void __exit fscache_exit(void)
 184{
 185        _enter("");
 186
 187        kobject_put(fscache_root);
 188        kmem_cache_destroy(fscache_cookie_jar);
 189#ifdef CONFIG_SYSCTL
 190        unregister_sysctl_table(fscache_sysctl_header);
 191#endif
 192        fscache_proc_cleanup();
 193        destroy_workqueue(fscache_op_wq);
 194        destroy_workqueue(fscache_object_wq);
 195        printk(KERN_NOTICE "FS-Cache: Unloaded\n");
 196}
 197
 198module_exit(fscache_exit);
 199
 200/*
 201 * wait_on_bit() sleep function for uninterruptible waiting
 202 */
 203int fscache_wait_bit(void *flags)
 204{
 205        schedule();
 206        return 0;
 207}
 208EXPORT_SYMBOL(fscache_wait_bit);
 209
 210/*
 211 * wait_on_bit() sleep function for interruptible waiting
 212 */
 213int fscache_wait_bit_interruptible(void *flags)
 214{
 215        schedule();
 216        return signal_pending(current);
 217}
 218EXPORT_SYMBOL(fscache_wait_bit_interruptible);
 219
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