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