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
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU General Public License version 2.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/kmod.h>
#include <linux/fs.h>
#include <linux/delay.h>
#include "lm_interface.h"
struct lmh_wrapper {
struct list_head lw_list;
struct lm_lockops *lw_ops;
};
/* List of registered low-level locking protocols. A file system selects one
of them by name at mount time, e.g. lock_nolock, lock_dlm. */
static LIST_HEAD(lmh_list);
static DEFINE_MUTEX(lmh_lock);
/**
* gfs2_register_lockproto - Register a low-level locking protocol
* @proto: the protocol definition
*
* Returns: 0 on success, -EXXX on failure
*/
int gfs2_register_lockproto(struct lm_lockops *proto)
{
struct lmh_wrapper *lw;
mutex_lock(&lmh_lock);
list_for_each_entry(lw, &lmh_list, lw_list) {
if (!strcmp(lw->lw_ops->lm_proto_name, proto->lm_proto_name)) {
mutex_unlock(&lmh_lock);
printk(KERN_INFO "GFS2: protocol %s already exists\n",
proto->lm_proto_name);
return -EEXIST;
}
}
lw = kzalloc(sizeof(struct lmh_wrapper), GFP_KERNEL);
if (!lw) {
mutex_unlock(&lmh_lock);
return -ENOMEM;
}
lw->lw_ops = proto;
list_add(&lw->lw_list, &lmh_list);
mutex_unlock(&lmh_lock);
return 0;
}
/**
* gfs2_unregister_lockproto - Unregister a low-level locking protocol
* @proto: the protocol definition
*
*/
void gfs2_unregister_lockproto(struct lm_lockops *proto)
{
struct lmh_wrapper *lw;
mutex_lock(&lmh_lock);
list_for_each_entry(lw, &lmh_list, lw_list) {
if (!strcmp(lw->lw_ops->lm_proto_name, proto->lm_proto_name)) {
list_del(&lw->lw_list);
mutex_unlock(&lmh_lock);
kfree(lw);
return;
}
}
mutex_unlock(&lmh_lock);
printk(KERN_WARNING "GFS2: can't unregister lock protocol %s\n",
proto->lm_proto_name);
}
/**
* gfs2_mount_lockproto - Mount a lock protocol
* @proto_name - the name of the protocol
* @table_name - the name of the lock space
* @host_data - data specific to this host
* @cb - the callback to the code using the lock module
* @fsdata - data to pass back with the callback
* @min_lvb_size - the mininum LVB size that the caller can deal with
* @flags - LM_MFLAG_*
* @lockstruct - a structure returned describing the mount
*
* Returns: 0 on success, -EXXX on failure
*/
int gfs2_mount_lockproto(char *proto_name, char *table_name, char *host_data,
lm_callback_t cb, lm_fsdata_t *fsdata,
unsigned int min_lvb_size, int flags,
struct lm_lockstruct *lockstruct,
struct kobject *fskobj)
{
struct lmh_wrapper *lw = NULL;
int try = 0;
int error, found;
retry:
mutex_lock(&lmh_lock);
found = 0;
list_for_each_entry(lw, &lmh_list, lw_list) {
if (!strcmp(lw->lw_ops->lm_proto_name, proto_name)) {
found = 1;
break;
}
}
if (!found) {
if (!try && capable(CAP_SYS_MODULE)) {
try = 1;
mutex_unlock(&lmh_lock);
request_module(proto_name);
goto retry;
}
printk(KERN_INFO "GFS2: can't find protocol %s\n", proto_name);
error = -ENOENT;
goto out;
}
if (!try_module_get(lw->lw_ops->lm_owner)) {
try = 0;
mutex_unlock(&lmh_lock);
msleep(1000);
goto retry;
}
error = lw->lw_ops->lm_mount(table_name, host_data, cb, fsdata,
min_lvb_size, flags, lockstruct, fskobj);
if (error)
module_put(lw->lw_ops->lm_owner);
out:
mutex_unlock(&lmh_lock);
return error;
}
void gfs2_unmount_lockproto(struct lm_lockstruct *lockstruct)
{
mutex_lock(&lmh_lock);
lockstruct->ls_ops->lm_unmount(lockstruct->ls_lockspace);
if (lockstruct->ls_ops->lm_owner)
module_put(lockstruct->ls_ops->lm_owner);
mutex_unlock(&lmh_lock);
}
/**
* gfs2_withdraw_lockproto - abnormally unmount a lock module
* @lockstruct: the lockstruct passed into mount
*
*/
void gfs2_withdraw_lockproto(struct lm_lockstruct *lockstruct)
{
mutex_lock(&lmh_lock);
lockstruct->ls_ops->lm_withdraw(lockstruct->ls_lockspace);
if (lockstruct->ls_ops->lm_owner)
module_put(lockstruct->ls_ops->lm_owner);
mutex_unlock(&lmh_lock);
}
EXPORT_SYMBOL_GPL(gfs2_register_lockproto);
EXPORT_SYMBOL_GPL(gfs2_unregister_lockproto);
|
