LXR linux/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
  17static LIST_HEAD(fscache_netfs_list);
  18
  19/*
  20 * register a network filesystem for caching
  21 */
  22int __fscache_register_netfs(struct fscache_netfs *netfs)
  23{
  24        struct fscache_netfs *ptr;
  25        int ret;
  26
  27        _enter("{%s}", netfs->name);
  28
  29        INIT_LIST_HEAD(&netfs->link);
  30
  31        /* allocate a cookie for the primary index */
  32        netfs->primary_index =
  33                kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
  34
  35        if (!netfs->primary_index) {
  36                _leave(" = -ENOMEM");
  37                return -ENOMEM;
  38        }
  39
  40        /* initialise the primary index cookie */
  41        atomic_set(&netfs->primary_index->usage, 1);
  42        atomic_set(&netfs->primary_index->n_children, 0);
  43        atomic_set(&netfs->primary_index->n_active, 1);
  44
  45        netfs->primary_index->def               = &fscache_fsdef_netfs_def;
  46        netfs->primary_index->parent            = &fscache_fsdef_index;
  47        netfs->primary_index->netfs_data        = netfs;
  48        netfs->primary_index->flags             = 1 << FSCACHE_COOKIE_ENABLED;
  49
  50        atomic_inc(&netfs->primary_index->parent->usage);
  51        atomic_inc(&netfs->primary_index->parent->n_children);
  52
  53        spin_lock_init(&netfs->primary_index->lock);
  54        INIT_HLIST_HEAD(&netfs->primary_index->backing_objects);
  55
  56        /* check the netfs type is not already present */
  57        down_write(&fscache_addremove_sem);
  58
  59        ret = -EEXIST;
  60        list_for_each_entry(ptr, &fscache_netfs_list, link) {
  61                if (strcmp(ptr->name, netfs->name) == 0)
  62                        goto already_registered;
  63        }
  64
  65        list_add(&netfs->link, &fscache_netfs_list);
  66        ret = 0;
  67
  68        pr_notice("Netfs '%s' registered for caching\n", netfs->name);
  69
  70already_registered:
  71        up_write(&fscache_addremove_sem);
  72
  73        if (ret < 0) {
  74                netfs->primary_index->parent = NULL;
  75                __fscache_cookie_put(netfs->primary_index);
  76                netfs->primary_index = NULL;
  77        }
  78
  79        _leave(" = %d", ret);
  80        return ret;
  81}
  82EXPORT_SYMBOL(__fscache_register_netfs);
  83
  84/*
  85 * unregister a network filesystem from the cache
  86 * - all cookies must have been released first
  87 */
  88void __fscache_unregister_netfs(struct fscache_netfs *netfs)
  89{
  90        _enter("{%s.%u}", netfs->name, netfs->version);
  91
  92        down_write(&fscache_addremove_sem);
  93
  94        list_del(&netfs->link);
  95        fscache_relinquish_cookie(netfs->primary_index, 0);
  96
  97        up_write(&fscache_addremove_sem);
  98
  99        pr_notice("Netfs '%s' unregistered from caching\n",
 100                  netfs->name);
 101
 102        _leave("");
 103}
 104EXPORT_SYMBOL(__fscache_unregister_netfs);
 105