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 ([email protected])
   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 *buffer, size_t *lenp, loff_t *ppos)
  55 {
  56         struct workqueue_struct **wqp = table->extra1;
  57         unsigned int *datap = table->data;
  58         int ret;
  59
  60         ret = proc_dointvec(table, write, buffer, lenp, ppos);
  61         if (ret == 0)
  62                 workqueue_set_max_active(*wqp, *datap);
  63         return ret;
  64 }
  65
  66 static struct ctl_table fscache_sysctls[] = {
  67         {
  68                 .procname       = "object_max_active",
  69                 .data           = &fscache_object_max_active,
  70                 .maxlen         = sizeof(unsigned),
  71                 .mode           = 0644,
  72                 .proc_handler   = fscache_max_active_sysctl,
  73                 .extra1         = &fscache_object_wq,
  74         },
  75         {
  76                 .procname       = "operation_max_active",
  77                 .data           = &fscache_op_max_active,
  78                 .maxlen         = sizeof(unsigned),
  79                 .mode           = 0644,
  80                 .proc_handler   = fscache_max_active_sysctl,
  81                 .extra1         = &fscache_op_wq,
  82         },
  83         {}
  84 };
  85
  86 static struct ctl_table fscache_sysctls_root[] = {
  87         {
  88                 .procname       = "fscache",
  89                 .mode           = 0555,
  90                 .child          = fscache_sysctls,
  91         },
  92         {}
  93 };
  94 #endif
  95
  96 /*
  97  * initialise the fs caching module
  98  */
  99 static int __init fscache_init(void)
 100 {
 101         unsigned int nr_cpus = num_possible_cpus();
 102         unsigned int cpu;
 103         int ret;
 104
 105         fscache_object_max_active =
 106                 clamp_val(nr_cpus,
 107                           fscache_object_max_active, WQ_UNBOUND_MAX_ACTIVE);
 108
 109         ret = -ENOMEM;
 110         fscache_object_wq = alloc_workqueue("fscache_object", WQ_UNBOUND,
 111                                             fscache_object_max_active);
 112         if (!fscache_object_wq)
 113                 goto error_object_wq;
 114
 115         fscache_op_max_active =
 116                 clamp_val(fscache_object_max_active / 2,
 117                           fscache_op_max_active, WQ_UNBOUND_MAX_ACTIVE);
 118
 119         ret = -ENOMEM;
 120         fscache_op_wq = alloc_workqueue("fscache_operation", WQ_UNBOUND,
 121                                         fscache_op_max_active);
 122         if (!fscache_op_wq)
 123                 goto error_op_wq;
 124
 125         for_each_possible_cpu(cpu)
 126                 init_waitqueue_head(&per_cpu(fscache_object_cong_wait, cpu));
 127
 128         ret = fscache_proc_init();
 129         if (ret < 0)
 130                 goto error_proc;
 131
 132 #ifdef CONFIG_SYSCTL
 133         ret = -ENOMEM;
 134         fscache_sysctl_header = register_sysctl_table(fscache_sysctls_root);
 135         if (!fscache_sysctl_header)
 136                 goto error_sysctl;
 137 #endif
 138
 139         fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar",
 140                                                sizeof(struct fscache_cookie),
 141                                                0, 0, NULL);
 142         if (!fscache_cookie_jar) {
 143                 pr_notice("Failed to allocate a cookie jar\n");
 144                 ret = -ENOMEM;
 145                 goto error_cookie_jar;
 146         }
 147
 148         fscache_root = kobject_create_and_add("fscache", kernel_kobj);
 149         if (!fscache_root)
 150                 goto error_kobj;
 151
 152         pr_notice("Loaded\n");
 153         return 0;
 154
 155 error_kobj:
 156         kmem_cache_destroy(fscache_cookie_jar);
 157 error_cookie_jar:
 158 #ifdef CONFIG_SYSCTL
 159         unregister_sysctl_table(fscache_sysctl_header);
 160 error_sysctl:
 161 #endif
 162         fscache_proc_cleanup();
 163 error_proc:
 164         destroy_workqueue(fscache_op_wq);
 165 error_op_wq:
 166         destroy_workqueue(fscache_object_wq);
 167 error_object_wq:
 168         return ret;
 169 }
 170
 171 fs_initcall(fscache_init);
 172
 173 /*
 174  * clean up on module removal
 175  */
 176 static void __exit fscache_exit(void)
 177 {
 178         _enter("");
 179
 180         kobject_put(fscache_root);
 181         kmem_cache_destroy(fscache_cookie_jar);
 182 #ifdef CONFIG_SYSCTL
 183         unregister_sysctl_table(fscache_sysctl_header);
 184 #endif
 185         fscache_proc_cleanup();
 186         destroy_workqueue(fscache_op_wq);
 187         destroy_workqueue(fscache_object_wq);
 188         pr_notice("Unloaded\n");
 189 }
 190
 191 module_exit(fscache_exit);