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 */
__fscache_register_netfs(struct fscache_netfs * netfs)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 /* 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
71 already_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 }
80 EXPORT_SYMBOL(__fscache_register_netfs);
81
82 /*
83 * unregister a network filesystem from the cache
84 * - all cookies must have been released first
85 */
__fscache_unregister_netfs(struct fscache_netfs * netfs)86 void __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 }
102 EXPORT_SYMBOL(__fscache_unregister_netfs);
103