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
 44	netfs->primary_index->def		= &fscache_fsdef_netfs_def;
 45	netfs->primary_index->parent		= &fscache_fsdef_index;
 46	netfs->primary_index->netfs_data	= netfs;
 47
 48	atomic_inc(&netfs->primary_index->parent->usage);
 49	atomic_inc(&netfs->primary_index->parent->n_children);
 50
 51	spin_lock_init(&netfs->primary_index->lock);
 52	INIT_HLIST_HEAD(&netfs->primary_index->backing_objects);
 53
 54	/* check the netfs type is not already present */
 55	down_write(&fscache_addremove_sem);
 56
 57	ret = -EEXIST;
 58	list_for_each_entry(ptr, &fscache_netfs_list, link) {
 59		if (strcmp(ptr->name, netfs->name) == 0)
 60			goto already_registered;
 61	}
 62
 63	list_add(&netfs->link, &fscache_netfs_list);
 64	ret = 0;
 65
 66	printk(KERN_NOTICE "FS-Cache: Netfs '%s' registered for caching\n",
 67	       netfs->name);
 68
 69already_registered:
 70	up_write(&fscache_addremove_sem);
 71
 72	if (ret < 0) {
 73		netfs->primary_index->parent = NULL;
 74		__fscache_cookie_put(netfs->primary_index);
 75		netfs->primary_index = NULL;
 76	}
 77
 78	_leave(" = %d", ret);
 79	return ret;
 80}
 81EXPORT_SYMBOL(__fscache_register_netfs);
 82
 83/*
 84 * unregister a network filesystem from the cache
 85 * - all cookies must have been released first
 86 */
 87void __fscache_unregister_netfs(struct fscache_netfs *netfs)
 88{
 89	_enter("{%s.%u}", netfs->name, netfs->version);
 90
 91	down_write(&fscache_addremove_sem);
 92
 93	list_del(&netfs->link);
 94	fscache_relinquish_cookie(netfs->primary_index, 0);
 95
 96	up_write(&fscache_addremove_sem);
 97
 98	printk(KERN_NOTICE "FS-Cache: Netfs '%s' unregistered from caching\n",
 99	       netfs->name);
100
101	_leave("");
102}
103EXPORT_SYMBOL(__fscache_unregister_netfs);