fs/fscache/main.c

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