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	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	/* initialise the primary index cookie */
 41	atomic_set(&cookie->usage, 1);
 42	atomic_set(&cookie->n_children, 0);
 43	atomic_set(&cookie->n_active, 1);
 44
 45	cookie->def		= &fscache_fsdef_netfs_def;
 46	cookie->parent		= &fscache_fsdef_index;
 47	cookie->netfs_data	= netfs;
 48	cookie->flags		= 1 << FSCACHE_COOKIE_ENABLED;
 49
 50	spin_lock_init(&cookie->lock);
 51	INIT_HLIST_HEAD(&cookie->backing_objects);
 52
 53	/* check the netfs type is not already present */
 54	down_write(&fscache_addremove_sem);
 55
 56	ret = -EEXIST;
 57	list_for_each_entry(ptr, &fscache_netfs_list, link) {
 58		if (strcmp(ptr->name, netfs->name) == 0)
 59			goto already_registered;
 60	}
 61
 62	atomic_inc(&cookie->parent->usage);
 63	atomic_inc(&cookie->parent->n_children);
 64
 65	netfs->primary_index = cookie;
 66	list_add(&netfs->link, &fscache_netfs_list);
 67	ret = 0;
 68
 69	pr_notice("Netfs '%s' registered for caching\n", netfs->name);
 70
 71already_registered:
 72	up_write(&fscache_addremove_sem);
 73
 74	if (ret < 0)
 75		kmem_cache_free(fscache_cookie_jar, cookie);
 76
 77	_leave(" = %d", ret);
 78	return ret;
 79}
 80EXPORT_SYMBOL(__fscache_register_netfs);
 81
 82/*
 83 * unregister a network filesystem from the cache
 84 * - all cookies must have been released first
 85 */
 86void __fscache_unregister_netfs(struct fscache_netfs *netfs)
 87{
 88	_enter("{%s.%u}", netfs->name, netfs->version);
 89
 90	down_write(&fscache_addremove_sem);
 91
 92	list_del(&netfs->link);
 93	fscache_relinquish_cookie(netfs->primary_index, 0);
 94
 95	up_write(&fscache_addremove_sem);
 96
 97	pr_notice("Netfs '%s' unregistered from caching\n",
 98		  netfs->name);
 99
100	_leave("");
101}
102EXPORT_SYMBOL(__fscache_unregister_netfs);