blob: 10a2ade0bdf8c1ff390be0e82c5dd2e161732054 [file] [log] [blame]
David Howellsa6891642009-04-03 16:42:37 +01001/* 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
16static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data,
17 void *buffer, uint16_t bufmax);
18
19static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data,
20 void *buffer, uint16_t bufmax);
21
22static
23enum 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 */
51static struct fscache_cookie_def fscache_fsdef_index_def = {
52 .name = ".FS-Cache",
53 .type = FSCACHE_COOKIE_TYPE_INDEX,
54};
55
56struct fscache_cookie fscache_fsdef_index = {
57 .usage = ATOMIC_INIT(1),
David Howells13627292013-05-10 19:50:26 +010058 .n_active = ATOMIC_INIT(1),
David Howellsa6891642009-04-03 16:42:37 +010059 .lock = __SPIN_LOCK_UNLOCKED(fscache_fsdef_index.lock),
60 .backing_objects = HLIST_HEAD_INIT,
61 .def = &fscache_fsdef_index_def,
62};
63EXPORT_SYMBOL(fscache_fsdef_index);
64
65/*
66 * Definition of an entry in the root index. Each entry is an index, keyed to
67 * a specific netfs and only applicable to a particular version of the index
68 * structure used by that netfs.
69 */
70struct fscache_cookie_def fscache_fsdef_netfs_def = {
71 .name = "FSDEF.netfs",
72 .type = FSCACHE_COOKIE_TYPE_INDEX,
73 .get_key = fscache_fsdef_netfs_get_key,
74 .get_aux = fscache_fsdef_netfs_get_aux,
75 .check_aux = fscache_fsdef_netfs_check_aux,
76};
77
78/*
79 * get the key data for an FSDEF index record - this is the name of the netfs
80 * for which this entry is created
81 */
82static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data,
83 void *buffer, uint16_t bufmax)
84{
85 const struct fscache_netfs *netfs = cookie_netfs_data;
86 unsigned klen;
87
88 _enter("{%s.%u},", netfs->name, netfs->version);
89
90 klen = strlen(netfs->name);
91 if (klen > bufmax)
92 return 0;
93
94 memcpy(buffer, netfs->name, klen);
95 return klen;
96}
97
98/*
99 * get the auxiliary data for an FSDEF index record - this is the index
100 * structure version number of the netfs for which this version is created
101 */
102static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data,
103 void *buffer, uint16_t bufmax)
104{
105 const struct fscache_netfs *netfs = cookie_netfs_data;
106 unsigned dlen;
107
108 _enter("{%s.%u},", netfs->name, netfs->version);
109
110 dlen = sizeof(uint32_t);
111 if (dlen > bufmax)
112 return 0;
113
114 memcpy(buffer, &netfs->version, dlen);
115 return dlen;
116}
117
118/*
119 * check that the index structure version number stored in the auxiliary data
120 * matches the one the netfs gave us
121 */
122static enum fscache_checkaux fscache_fsdef_netfs_check_aux(
123 void *cookie_netfs_data,
124 const void *data,
125 uint16_t datalen)
126{
127 struct fscache_netfs *netfs = cookie_netfs_data;
128 uint32_t version;
129
130 _enter("{%s},,%hu", netfs->name, datalen);
131
132 if (datalen != sizeof(version)) {
133 _leave(" = OBSOLETE [dl=%d v=%zu]", datalen, sizeof(version));
134 return FSCACHE_CHECKAUX_OBSOLETE;
135 }
136
137 memcpy(&version, data, sizeof(version));
138 if (version != netfs->version) {
139 _leave(" = OBSOLETE [ver=%x net=%x]", version, netfs->version);
140 return FSCACHE_CHECKAUX_OBSOLETE;
141 }
142
143 _leave(" = OKAY");
144 return FSCACHE_CHECKAUX_OKAY;
145}