Commit | Line | Data |
---|---|---|
a6891645 DH |
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 | ||
16 | static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data, | |
17 | void *buffer, uint16_t bufmax); | |
18 | ||
19 | static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data, | |
20 | void *buffer, uint16_t bufmax); | |
21 | ||
22 | static | |
23 | enum fscache_checkaux fscache_fsdef_netfs_check_aux(void *cookie_netfs_data, | |
24 | const void *data, | |
25 | uint16_t datalen); | |
26 | ||
27 | /* | |
28 | * The root index is owned by FS-Cache itself. | |
29 | * | |
30 | * When a netfs requests caching facilities, FS-Cache will, if one doesn't | |
31 | * already exist, create an entry in the root index with the key being the name | |
32 | * of the netfs ("AFS" for example), and the auxiliary data holding the index | |
33 | * structure version supplied by the netfs: | |
34 | * | |
35 | * FSDEF | |
36 | * | | |
37 | * +-----------+ | |
38 | * | | | |
39 | * NFS AFS | |
40 | * [v=1] [v=1] | |
41 | * | |
42 | * If an entry with the appropriate name does already exist, the version is | |
43 | * compared. If the version is different, the entire subtree from that entry | |
44 | * will be discarded and a new entry created. | |
45 | * | |
46 | * The new entry will be an index, and a cookie referring to it will be passed | |
47 | * to the netfs. This is then the root handle by which the netfs accesses the | |
48 | * cache. It can create whatever objects it likes in that index, including | |
49 | * further indices. | |
50 | */ | |
51 | static struct fscache_cookie_def fscache_fsdef_index_def = { | |
52 | .name = ".FS-Cache", | |
53 | .type = FSCACHE_COOKIE_TYPE_INDEX, | |
54 | }; | |
55 | ||
56 | struct fscache_cookie fscache_fsdef_index = { | |
57 | .usage = ATOMIC_INIT(1), | |
1362729b | 58 | .n_active = ATOMIC_INIT(1), |
a6891645 DH |
59 | .lock = __SPIN_LOCK_UNLOCKED(fscache_fsdef_index.lock), |
60 | .backing_objects = HLIST_HEAD_INIT, | |
61 | .def = &fscache_fsdef_index_def, | |
94d30ae9 | 62 | .flags = 1 << FSCACHE_COOKIE_ENABLED, |
a6891645 DH |
63 | }; |
64 | EXPORT_SYMBOL(fscache_fsdef_index); | |
65 | ||
66 | /* | |
67 | * Definition of an entry in the root index. Each entry is an index, keyed to | |
68 | * a specific netfs and only applicable to a particular version of the index | |
69 | * structure used by that netfs. | |
70 | */ | |
71 | struct fscache_cookie_def fscache_fsdef_netfs_def = { | |
72 | .name = "FSDEF.netfs", | |
73 | .type = FSCACHE_COOKIE_TYPE_INDEX, | |
74 | .get_key = fscache_fsdef_netfs_get_key, | |
75 | .get_aux = fscache_fsdef_netfs_get_aux, | |
76 | .check_aux = fscache_fsdef_netfs_check_aux, | |
77 | }; | |
78 | ||
79 | /* | |
80 | * get the key data for an FSDEF index record - this is the name of the netfs | |
81 | * for which this entry is created | |
82 | */ | |
83 | static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data, | |
84 | void *buffer, uint16_t bufmax) | |
85 | { | |
86 | const struct fscache_netfs *netfs = cookie_netfs_data; | |
87 | unsigned klen; | |
88 | ||
89 | _enter("{%s.%u},", netfs->name, netfs->version); | |
90 | ||
91 | klen = strlen(netfs->name); | |
92 | if (klen > bufmax) | |
93 | return 0; | |
94 | ||
95 | memcpy(buffer, netfs->name, klen); | |
96 | return klen; | |
97 | } | |
98 | ||
99 | /* | |
100 | * get the auxiliary data for an FSDEF index record - this is the index | |
101 | * structure version number of the netfs for which this version is created | |
102 | */ | |
103 | static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data, | |
104 | void *buffer, uint16_t bufmax) | |
105 | { | |
106 | const struct fscache_netfs *netfs = cookie_netfs_data; | |
107 | unsigned dlen; | |
108 | ||
109 | _enter("{%s.%u},", netfs->name, netfs->version); | |
110 | ||
111 | dlen = sizeof(uint32_t); | |
112 | if (dlen > bufmax) | |
113 | return 0; | |
114 | ||
115 | memcpy(buffer, &netfs->version, dlen); | |
116 | return dlen; | |
117 | } | |
118 | ||
119 | /* | |
120 | * check that the index structure version number stored in the auxiliary data | |
121 | * matches the one the netfs gave us | |
122 | */ | |
123 | static enum fscache_checkaux fscache_fsdef_netfs_check_aux( | |
124 | void *cookie_netfs_data, | |
125 | const void *data, | |
126 | uint16_t datalen) | |
127 | { | |
128 | struct fscache_netfs *netfs = cookie_netfs_data; | |
129 | uint32_t version; | |
130 | ||
131 | _enter("{%s},,%hu", netfs->name, datalen); | |
132 | ||
133 | if (datalen != sizeof(version)) { | |
134 | _leave(" = OBSOLETE [dl=%d v=%zu]", datalen, sizeof(version)); | |
135 | return FSCACHE_CHECKAUX_OBSOLETE; | |
136 | } | |
137 | ||
138 | memcpy(&version, data, sizeof(version)); | |
139 | if (version != netfs->version) { | |
140 | _leave(" = OBSOLETE [ver=%x net=%x]", version, netfs->version); | |
141 | return FSCACHE_CHECKAUX_OBSOLETE; | |
142 | } | |
143 | ||
144 | _leave(" = OKAY"); | |
145 | return FSCACHE_CHECKAUX_OKAY; | |
146 | } |