fs/cachefiles/cf-main.c

   1 /* cf-main.c: network filesystem caching backend to use cache files on a
   2  *            premounted filesystem
   3  *
   4  * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version
  10  * 2 of the License, or (at your option) any later version.
  11  */
  12
  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/fs.h>
  19 #include <linux/file.h>
  20 #include <linux/namei.h>
  21 #include <linux/mount.h>
  22 #include <linux/statfs.h>
  23 #include <linux/proc_fs.h>
  24 #include <linux/sysctl.h>
  25 #include "internal.h"
  26
  27 unsigned long cachefiles_debug;
  28
  29 static int cachefiles_init(void);
  30 static void cachefiles_exit(void);
  31
  32 fs_initcall(cachefiles_init);
  33 module_exit(cachefiles_exit);
  34
  35 MODULE_DESCRIPTION("Mounted-filesystem based cache");
  36 MODULE_AUTHOR("Red Hat, Inc.");
  37 MODULE_LICENSE("GPL");
  38
  39 kmem_cache_t *cachefiles_object_jar;
  40
  41 static void cachefiles_object_init_once(void *_object, kmem_cache_t *cachep,
  42                                         unsigned long flags)
  43 {
  44         struct cachefiles_object *object = _object;
  45
  46         switch (flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) {
  47         case SLAB_CTOR_CONSTRUCTOR:
  48                 memset(object, 0, sizeof(*object));
  49                 fscache_object_init(&object->fscache);
  50                 init_rwsem(&object->sem);
  51                 spin_lock_init(&object->work_lock);
  52                 INIT_LIST_HEAD(&object->read_list);
  53                 INIT_LIST_HEAD(&object->read_pend_list);
  54                 INIT_WORK(&object->read_work, &cachefiles_read_copier_work,
  55                           object);
  56                 INIT_LIST_HEAD(&object->write_list);
  57                 INIT_WORK(&object->write_work, &cachefiles_write_work, object);
  58                 break;
  59
  60         default:
  61                 break;
  62         }
  63 }
  64
  65 /*****************************************************************************/
  66 /*
  67  * initialise the fs caching module
  68  */
  69 static int __init cachefiles_init(void)
  70 {
  71         struct proc_dir_entry *pde;
  72         int ret;
  73
  74         /* create a proc entry to use as a handle for the userspace daemon */
  75         ret = -ENOMEM;
  76
  77         pde = create_proc_entry("cachefiles", 0600, proc_root_fs);
  78         if (!pde) {
  79                 kerror("Unable to create /proc/fs/cachefiles");
  80                 goto error_proc;
  81         }
  82
  83         if (cachefiles_sysctl_init() < 0) {
  84                 kerror("Unable to create sysctl parameters");
  85                 goto error_object_jar;
  86         }
  87
  88         pde->owner = THIS_MODULE;
  89         pde->proc_fops = &cachefiles_proc_fops;
  90         cachefiles_proc = pde;
  91
  92         /* create an object jar */
  93         cachefiles_object_jar =
  94                 kmem_cache_create("cachefiles_object_jar",
  95                                   sizeof(struct cachefiles_object),
  96                                   0,
  97                                   SLAB_HWCACHE_ALIGN,
  98                                   cachefiles_object_init_once,
  99                                   NULL);
 100         if (!cachefiles_object_jar) {
 101                 printk(KERN_NOTICE
 102                        "CacheFiles: Failed to allocate an object jar\n");
 103                 goto error_sysctl;
 104         }
 105
 106         printk(KERN_INFO "CacheFiles: Loaded\n");
 107         return 0;
 108
 109 error_sysctl:
 110         cachefiles_sysctl_cleanup();
 111 error_object_jar:
 112         remove_proc_entry("cachefiles", proc_root_fs);
 113 error_proc:
 114         kerror("failed to register: %d", ret);
 115         return ret;
 116 }
 117
 118 /*****************************************************************************/
 119 /*
 120  * clean up on module removal
 121  */
 122 static void __exit cachefiles_exit(void)
 123 {
 124         printk(KERN_INFO "CacheFiles: Unloading\n");
 125
 126         kmem_cache_destroy(cachefiles_object_jar);
 127         remove_proc_entry("cachefiles", proc_root_fs);
 128         cachefiles_sysctl_cleanup();
 129 }