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1 | /* Filesystem index definition |
2 | * | |
3 | * Copyright (C) 2004-2007 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 License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #define FSCACHE_DEBUG_LEVEL CACHE | |
13 | #include <linux/module.h> | |
14 | #include "internal.h" | |
15 | ||
a6891645 DH |
16 | static |
17 | enum fscache_checkaux fscache_fsdef_netfs_check_aux(void *cookie_netfs_data, | |
18 | const void *data, | |
ee1235a9 DH |
19 | uint16_t datalen, |
20 | loff_t object_size); | |
a6891645 DH |
21 | |
22 | /* | |
23 | * The root index is owned by FS-Cache itself. | |
24 | * | |
25 | * When a netfs requests caching facilities, FS-Cache will, if one doesn't | |
26 | * already exist, create an entry in the root index with the key being the name | |
27 | * of the netfs ("AFS" for example), and the auxiliary data holding the index | |
28 | * structure version supplied by the netfs: | |
29 | * | |
30 | * FSDEF | |
31 | * | | |
32 | * +-----------+ | |
33 | * | | | |
34 | * NFS AFS | |
35 | * [v=1] [v=1] | |
36 | * | |
37 | * If an entry with the appropriate name does already exist, the version is | |
38 | * compared. If the version is different, the entire subtree from that entry | |
39 | * will be discarded and a new entry created. | |
40 | * | |
41 | * The new entry will be an index, and a cookie referring to it will be passed | |
42 | * to the netfs. This is then the root handle by which the netfs accesses the | |
43 | * cache. It can create whatever objects it likes in that index, including | |
44 | * further indices. | |
45 | */ | |
46 | static struct fscache_cookie_def fscache_fsdef_index_def = { | |
47 | .name = ".FS-Cache", | |
48 | .type = FSCACHE_COOKIE_TYPE_INDEX, | |
49 | }; | |
50 | ||
51 | struct fscache_cookie fscache_fsdef_index = { | |
52 | .usage = ATOMIC_INIT(1), | |
1362729b | 53 | .n_active = ATOMIC_INIT(1), |
a6891645 DH |
54 | .lock = __SPIN_LOCK_UNLOCKED(fscache_fsdef_index.lock), |
55 | .backing_objects = HLIST_HEAD_INIT, | |
56 | .def = &fscache_fsdef_index_def, | |
94d30ae9 | 57 | .flags = 1 << FSCACHE_COOKIE_ENABLED, |
402cb8dd | 58 | .type = FSCACHE_COOKIE_TYPE_INDEX, |
a6891645 DH |
59 | }; |
60 | EXPORT_SYMBOL(fscache_fsdef_index); | |
61 | ||
62 | /* | |
63 | * Definition of an entry in the root index. Each entry is an index, keyed to | |
64 | * a specific netfs and only applicable to a particular version of the index | |
65 | * structure used by that netfs. | |
66 | */ | |
67 | struct fscache_cookie_def fscache_fsdef_netfs_def = { | |
68 | .name = "FSDEF.netfs", | |
69 | .type = FSCACHE_COOKIE_TYPE_INDEX, | |
a6891645 DH |
70 | .check_aux = fscache_fsdef_netfs_check_aux, |
71 | }; | |
72 | ||
a6891645 DH |
73 | /* |
74 | * check that the index structure version number stored in the auxiliary data | |
75 | * matches the one the netfs gave us | |
76 | */ | |
77 | static enum fscache_checkaux fscache_fsdef_netfs_check_aux( | |
78 | void *cookie_netfs_data, | |
79 | const void *data, | |
ee1235a9 DH |
80 | uint16_t datalen, |
81 | loff_t object_size) | |
a6891645 DH |
82 | { |
83 | struct fscache_netfs *netfs = cookie_netfs_data; | |
84 | uint32_t version; | |
85 | ||
86 | _enter("{%s},,%hu", netfs->name, datalen); | |
87 | ||
88 | if (datalen != sizeof(version)) { | |
89 | _leave(" = OBSOLETE [dl=%d v=%zu]", datalen, sizeof(version)); | |
90 | return FSCACHE_CHECKAUX_OBSOLETE; | |
91 | } | |
92 | ||
93 | memcpy(&version, data, sizeof(version)); | |
94 | if (version != netfs->version) { | |
95 | _leave(" = OBSOLETE [ver=%x net=%x]", version, netfs->version); | |
96 | return FSCACHE_CHECKAUX_OBSOLETE; | |
97 | } | |
98 | ||
99 | _leave(" = OKAY"); | |
100 | return FSCACHE_CHECKAUX_OKAY; | |
101 | } |