cache_lib.c
3.83 KB
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
/*
* linux/fs/nfs/cache_lib.c
*
* Helper routines for the NFS client caches
*
* Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
*/
#include <linux/kmod.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/slab.h>
#include <linux/sunrpc/cache.h>
#include <linux/sunrpc/rpc_pipe_fs.h>
#include <net/net_namespace.h>
#include "cache_lib.h"
#define NFS_CACHE_UPCALL_PATHLEN 256
#define NFS_CACHE_UPCALL_TIMEOUT 15
static char nfs_cache_getent_prog[NFS_CACHE_UPCALL_PATHLEN] =
"/sbin/nfs_cache_getent";
static unsigned long nfs_cache_getent_timeout = NFS_CACHE_UPCALL_TIMEOUT;
module_param_string(cache_getent, nfs_cache_getent_prog,
sizeof(nfs_cache_getent_prog), 0600);
MODULE_PARM_DESC(cache_getent, "Path to the client cache upcall program");
module_param_named(cache_getent_timeout, nfs_cache_getent_timeout, ulong, 0600);
MODULE_PARM_DESC(cache_getent_timeout, "Timeout (in seconds) after which "
"the cache upcall is assumed to have failed");
int nfs_cache_upcall(struct cache_detail *cd, char *entry_name)
{
static char *envp[] = { "HOME=/",
"TERM=linux",
"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
NULL
};
char *argv[] = {
nfs_cache_getent_prog,
cd->name,
entry_name,
NULL
};
int ret = -EACCES;
if (nfs_cache_getent_prog[0] == '\0')
goto out;
ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
/*
* Disable the upcall mechanism if we're getting an ENOENT or
* EACCES error. The admin can re-enable it on the fly by using
* sysfs to set the 'cache_getent' parameter once the problem
* has been fixed.
*/
if (ret == -ENOENT || ret == -EACCES)
nfs_cache_getent_prog[0] = '\0';
out:
return ret > 0 ? 0 : ret;
}
/*
* Deferred request handling
*/
void nfs_cache_defer_req_put(struct nfs_cache_defer_req *dreq)
{
if (atomic_dec_and_test(&dreq->count))
kfree(dreq);
}
static void nfs_dns_cache_revisit(struct cache_deferred_req *d, int toomany)
{
struct nfs_cache_defer_req *dreq;
dreq = container_of(d, struct nfs_cache_defer_req, deferred_req);
complete_all(&dreq->completion);
nfs_cache_defer_req_put(dreq);
}
static struct cache_deferred_req *nfs_dns_cache_defer(struct cache_req *req)
{
struct nfs_cache_defer_req *dreq;
dreq = container_of(req, struct nfs_cache_defer_req, req);
dreq->deferred_req.revisit = nfs_dns_cache_revisit;
atomic_inc(&dreq->count);
return &dreq->deferred_req;
}
struct nfs_cache_defer_req *nfs_cache_defer_req_alloc(void)
{
struct nfs_cache_defer_req *dreq;
dreq = kzalloc(sizeof(*dreq), GFP_KERNEL);
if (dreq) {
init_completion(&dreq->completion);
atomic_set(&dreq->count, 1);
dreq->req.defer = nfs_dns_cache_defer;
}
return dreq;
}
int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req *dreq)
{
if (wait_for_completion_timeout(&dreq->completion,
nfs_cache_getent_timeout * HZ) == 0)
return -ETIMEDOUT;
return 0;
}
int nfs_cache_register_sb(struct super_block *sb, struct cache_detail *cd)
{
int ret;
struct dentry *dir;
dir = rpc_d_lookup_sb(sb, "cache");
ret = sunrpc_cache_register_pipefs(dir, cd->name, 0600, cd);
dput(dir);
return ret;
}
int nfs_cache_register_net(struct net *net, struct cache_detail *cd)
{
struct super_block *pipefs_sb;
int ret = 0;
sunrpc_init_cache_detail(cd);
pipefs_sb = rpc_get_sb_net(net);
if (pipefs_sb) {
ret = nfs_cache_register_sb(pipefs_sb, cd);
rpc_put_sb_net(net);
if (ret)
sunrpc_destroy_cache_detail(cd);
}
return ret;
}
void nfs_cache_unregister_sb(struct super_block *sb, struct cache_detail *cd)
{
if (cd->u.pipefs.dir)
sunrpc_cache_unregister_pipefs(cd);
}
void nfs_cache_unregister_net(struct net *net, struct cache_detail *cd)
{
struct super_block *pipefs_sb;
pipefs_sb = rpc_get_sb_net(net);
if (pipefs_sb) {
nfs_cache_unregister_sb(pipefs_sb, cd);
rpc_put_sb_net(net);
}
sunrpc_destroy_cache_detail(cd);
}