fs/fscache/main.c

   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
  21 MODULE_DESCRIPTION("FS Cache Manager");
  22 MODULE_AUTHOR("Red Hat, Inc.");
  23 MODULE_LICENSE("GPL");
  24
  25 unsigned fscache_defer_lookup = 1;
  26 module_param_named(defer_lookup, fscache_defer_lookup, uint,
  27                    S_IWUSR | S_IRUGO);
  28 MODULE_PARM_DESC(fscache_defer_lookup,
  29                  "Defer cookie lookup to background thread");
  30
  31 unsigned fscache_defer_create = 1;
  32 module_param_named(defer_create, fscache_defer_create, uint,
  33                    S_IWUSR | S_IRUGO);
  34 MODULE_PARM_DESC(fscache_defer_create,
  35                  "Defer cookie creation to background thread");
  36
  37 unsigned fscache_debug;
  38 module_param_named(debug, fscache_debug, uint,
  39                    S_IWUSR | S_IRUGO);
  40 MODULE_PARM_DESC(fscache_debug,
  41                  "FS-Cache debugging mask");
  42
  43 struct kobject *fscache_root;
  44 struct workqueue_struct *fscache_object_wq;
  45 struct workqueue_struct *fscache_op_wq;
  46
  47 DEFINE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait);
  48
  49 /* these values serve as lower bounds, will be adjusted in fscache_init() */
  50 static unsigned fscache_object_max_active = 4;
  51 static unsigned fscache_op_max_active = 2;
  52
  53 #ifdef CONFIG_SYSCTL
  54 static struct ctl_table_header *fscache_sysctl_header;
  55
  56 static 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
  70 static 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
  90 static 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  */
 103 static 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
 161 error_kobj:
 162         kmem_cache_destroy(fscache_cookie_jar);
 163 error_cookie_jar:
 164 #ifdef CONFIG_SYSCTL
 165         unregister_sysctl_table(fscache_sysctl_header);
 166 error_sysctl:
 167 #endif
 168         fscache_proc_cleanup();
 169 error_proc:
 170         destroy_workqueue(fscache_op_wq);
 171 error_op_wq:
 172         destroy_workqueue(fscache_object_wq);
 173 error_object_wq:
 174         return ret;
 175 }
 176
 177 fs_initcall(fscache_init);
 178
 179 /*
 180  * clean up on module removal
 181  */
 182 static 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
 197 module_exit(fscache_exit);
 198
 199 /*
 200  * wait_on_atomic_t() sleep function for uninterruptible waiting
 201  */
 202 int fscache_wait_atomic_t(atomic_t *p)
 203 {
 204         schedule();
 205         return 0;
 206 }