fs/fscache/netfs.c

   1 /* FS-Cache netfs (client) registration
   2  *
   3  * Copyright (C) 2008 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 Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11
  12 #define FSCACHE_DEBUG_LEVEL COOKIE
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15 #include "internal.h"
  16
  17 static LIST_HEAD(fscache_netfs_list);
  18
  19 /*
  20  * register a network filesystem for caching
  21  */
  22 int __fscache_register_netfs(struct fscache_netfs *netfs)
  23 {
  24         struct fscache_netfs *ptr;
  25         struct fscache_cookie *cookie;
  26         int ret;
  27
  28         _enter("{%s}", netfs->name);
  29
  30         INIT_LIST_HEAD(&netfs->link);
  31
  32         /* allocate a cookie for the primary index */
  33         cookie = kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
  34
  35         if (!cookie) {
  36                 _leave(" = -ENOMEM");
  37                 return -ENOMEM;
  38         }
  39
  40         cookie->key_len = strlen(netfs->name);
  41         if (cookie->key_len <= sizeof(cookie->inline_key)) {
  42                 memcpy(cookie->inline_key, netfs->name, strlen(netfs->name));
  43         } else {
  44                 ret = -ENOMEM;
  45                 cookie->key = kmemdup(netfs->name, cookie->key_len, GFP_KERNEL);
  46                 if (!cookie->key)
  47                         goto nomem;
  48         }
  49
  50         cookie->aux_len = sizeof(netfs->version);
  51         memcpy(cookie->inline_aux, &netfs->version, cookie->aux_len);
  52
  53         /* initialise the primary index cookie */
  54         atomic_set(&cookie->usage, 1);
  55         atomic_set(&cookie->n_children, 0);
  56         atomic_set(&cookie->n_active, 1);
  57
  58         cookie->def             = &fscache_fsdef_netfs_def;
  59         cookie->parent          = &fscache_fsdef_index;
  60         cookie->netfs_data      = netfs;
  61         cookie->flags           = 1 << FSCACHE_COOKIE_ENABLED;
  62         cookie->type            = FSCACHE_COOKIE_TYPE_INDEX;
  63
  64         spin_lock_init(&cookie->lock);
  65         spin_lock_init(&cookie->stores_lock);
  66         INIT_HLIST_HEAD(&cookie->backing_objects);
  67
  68         /* check the netfs type is not already present */
  69         down_write(&fscache_addremove_sem);
  70
  71         ret = -EEXIST;
  72         list_for_each_entry(ptr, &fscache_netfs_list, link) {
  73                 if (strcmp(ptr->name, netfs->name) == 0)
  74                         goto already_registered;
  75         }
  76
  77         fscache_cookie_get(cookie->parent, fscache_cookie_get_register_netfs);
  78         atomic_inc(&cookie->parent->n_children);
  79
  80         netfs->primary_index = cookie;
  81         list_add(&netfs->link, &fscache_netfs_list);
  82         ret = 0;
  83
  84         pr_notice("Netfs '%s' registered for caching\n", netfs->name);
  85         trace_fscache_netfs(netfs);
  86
  87 already_registered:
  88         up_write(&fscache_addremove_sem);
  89
  90 nomem:
  91         if (ret < 0)
  92                 kmem_cache_free(fscache_cookie_jar, cookie);
  93
  94         _leave(" = %d", ret);
  95         return ret;
  96 }
  97 EXPORT_SYMBOL(__fscache_register_netfs);
  98
  99 /*
 100  * unregister a network filesystem from the cache
 101  * - all cookies must have been released first
 102  */
 103 void __fscache_unregister_netfs(struct fscache_netfs *netfs)
 104 {
 105         _enter("{%s.%u}", netfs->name, netfs->version);
 106
 107         down_write(&fscache_addremove_sem);
 108
 109         list_del(&netfs->link);
 110         fscache_relinquish_cookie(netfs->primary_index, NULL, false);
 111
 112         up_write(&fscache_addremove_sem);
 113
 114         pr_notice("Netfs '%s' unregistered from caching\n",
 115                   netfs->name);
 116
 117         _leave("");
 118 }
 119 EXPORT_SYMBOL(__fscache_unregister_netfs);