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 #define CREATE_TRACE_POINTS
  20 #include "internal.h"
  21
  22 MODULE_DESCRIPTION("FS Cache Manager");
  23 MODULE_AUTHOR("Red Hat, Inc.");
  24 MODULE_LICENSE("GPL");
  25
  26 unsigned fscache_defer_lookup = 1;
  27 module_param_named(defer_lookup, fscache_defer_lookup, uint,
  28                    S_IWUSR | S_IRUGO);
  29 MODULE_PARM_DESC(fscache_defer_lookup,
  30                  "Defer cookie lookup to background thread");
  31
  32 unsigned fscache_defer_create = 1;
  33 module_param_named(defer_create, fscache_defer_create, uint,
  34                    S_IWUSR | S_IRUGO);
  35 MODULE_PARM_DESC(fscache_defer_create,
  36                  "Defer cookie creation to background thread");
  37
  38 unsigned fscache_debug;
  39 module_param_named(debug, fscache_debug, uint,
  40                    S_IWUSR | S_IRUGO);
  41 MODULE_PARM_DESC(fscache_debug,
  42                  "FS-Cache debugging mask");
  43
  44 struct kobject *fscache_root;
  45 struct workqueue_struct *fscache_object_wq;
  46 struct workqueue_struct *fscache_op_wq;
  47
  48 DEFINE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait);
  49
  50 /* these values serve as lower bounds, will be adjusted in fscache_init() */
  51 static unsigned fscache_object_max_active = 4;
  52 static unsigned fscache_op_max_active = 2;
  53
  54 #ifdef CONFIG_SYSCTL
  55 static struct ctl_table_header *fscache_sysctl_header;
  56
  57 static 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
  71 static 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
  91 static 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  */
 104 static 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,
 147                                                0,
 148                                                fscache_cookie_init_once);
 149         if (!fscache_cookie_jar) {
 150                 pr_notice("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         pr_notice("Loaded\n");
 160         return 0;
 161
 162 error_kobj:
 163         kmem_cache_destroy(fscache_cookie_jar);
 164 error_cookie_jar:
 165 #ifdef CONFIG_SYSCTL
 166         unregister_sysctl_table(fscache_sysctl_header);
 167 error_sysctl:
 168 #endif
 169         fscache_proc_cleanup();
 170 error_proc:
 171         destroy_workqueue(fscache_op_wq);
 172 error_op_wq:
 173         destroy_workqueue(fscache_object_wq);
 174 error_object_wq:
 175         return ret;
 176 }
 177
 178 fs_initcall(fscache_init);
 179
 180 /*
 181  * clean up on module removal
 182  */
 183 static 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         pr_notice("Unloaded\n");
 196 }
 197
 198 module_exit(fscache_exit);