1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
|
/* Filesystem index definition
*
* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL CACHE
#include <linux/module.h>
#include "internal.h"
static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax);
static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax);
static
enum fscache_checkaux fscache_fsdef_netfs_check_aux(void *cookie_netfs_data,
const void *data,
uint16_t datalen);
/*
* The root index is owned by FS-Cache itself.
*
* When a netfs requests caching facilities, FS-Cache will, if one doesn't
* already exist, create an entry in the root index with the key being the name
* of the netfs ("AFS" for example), and the auxiliary data holding the index
* structure version supplied by the netfs:
*
* FSDEF
* |
* +-----------+
* | |
* NFS AFS
* [v=1] [v=1]
*
* If an entry with the appropriate name does already exist, the version is
* compared. If the version is different, the entire subtree from that entry
* will be discarded and a new entry created.
*
* The new entry will be an index, and a cookie referring to it will be passed
* to the netfs. This is then the root handle by which the netfs accesses the
* cache. It can create whatever objects it likes in that index, including
* further indices.
*/
static struct fscache_cookie_def fscache_fsdef_index_def = {
.name = ".FS-Cache",
.type = FSCACHE_COOKIE_TYPE_INDEX,
};
struct fscache_cookie fscache_fsdef_index = {
.usage = ATOMIC_INIT(1),
.n_active = ATOMIC_INIT(1),
.lock = __SPIN_LOCK_UNLOCKED(fscache_fsdef_index.lock),
.backing_objects = HLIST_HEAD_INIT,
.def = &fscache_fsdef_index_def,
};
EXPORT_SYMBOL(fscache_fsdef_index);
/*
* Definition of an entry in the root index. Each entry is an index, keyed to
* a specific netfs and only applicable to a particular version of the index
* structure used by that netfs.
*/
struct fscache_cookie_def fscache_fsdef_netfs_def = {
.name = "FSDEF.netfs",
.type = FSCACHE_COOKIE_TYPE_INDEX,
.get_key = fscache_fsdef_netfs_get_key,
.get_aux = fscache_fsdef_netfs_get_aux,
.check_aux = fscache_fsdef_netfs_check_aux,
};
/*
* get the key data for an FSDEF index record - this is the name of the netfs
* for which this entry is created
*/
static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct fscache_netfs *netfs = cookie_netfs_data;
unsigned klen;
_enter("{%s.%u},", netfs->name, netfs->version);
klen = strlen(netfs->name);
if (klen > bufmax)
return 0;
memcpy(buffer, netfs->name, klen);
return klen;
}
/*
* get the auxiliary data for an FSDEF index record - this is the index
* structure version number of the netfs for which this version is created
*/
static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct fscache_netfs *netfs = cookie_netfs_data;
unsigned dlen;
_enter("{%s.%u},", netfs->name, netfs->version);
dlen = sizeof(uint32_t);
if (dlen > bufmax)
return 0;
memcpy(buffer, &netfs->version, dlen);
return dlen;
}
/*
* check that the index structure version number stored in the auxiliary data
* matches the one the netfs gave us
*/
static enum fscache_checkaux fscache_fsdef_netfs_check_aux(
void *cookie_netfs_data,
const void *data,
uint16_t datalen)
{
struct fscache_netfs *netfs = cookie_netfs_data;
uint32_t version;
_enter("{%s},,%hu", netfs->name, datalen);
if (datalen != sizeof(version)) {
_leave(" = OBSOLETE [dl=%d v=%zu]", datalen, sizeof(version));
return FSCACHE_CHECKAUX_OBSOLETE;
}
memcpy(&version, data, sizeof(version));
if (version != netfs->version) {
_leave(" = OBSOLETE [ver=%x net=%x]", version, netfs->version);
return FSCACHE_CHECKAUX_OBSOLETE;
}
_leave(" = OKAY");
return FSCACHE_CHECKAUX_OKAY;
}
|
