fuse: do not use iocb after it may have been freed
[firefly-linux-kernel-4.4.55.git] / 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
17 static LIST_HEAD(fscache_netfs_list);
18
19 /*
20  * register a network filesystem for caching
21  */
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  */
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);