Commit | Line | Data |
---|---|---|
e571cbf1 TM |
1 | /* |
2 | * linux/fs/nfs/cache_lib.c | |
3 | * | |
4 | * Helper routines for the NFS client caches | |
5 | * | |
6 | * Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com> | |
7 | */ | |
8 | #include <linux/kmod.h> | |
9 | #include <linux/module.h> | |
10 | #include <linux/moduleparam.h> | |
11 | #include <linux/mount.h> | |
12 | #include <linux/namei.h> | |
13 | #include <linux/sunrpc/cache.h> | |
14 | #include <linux/sunrpc/rpc_pipe_fs.h> | |
15 | ||
16 | #include "cache_lib.h" | |
17 | ||
18 | #define NFS_CACHE_UPCALL_PATHLEN 256 | |
19 | #define NFS_CACHE_UPCALL_TIMEOUT 15 | |
20 | ||
21 | static char nfs_cache_getent_prog[NFS_CACHE_UPCALL_PATHLEN] = | |
22 | "/sbin/nfs_cache_getent"; | |
23 | static unsigned long nfs_cache_getent_timeout = NFS_CACHE_UPCALL_TIMEOUT; | |
24 | ||
25 | module_param_string(cache_getent, nfs_cache_getent_prog, | |
26 | sizeof(nfs_cache_getent_prog), 0600); | |
27 | MODULE_PARM_DESC(cache_getent, "Path to the client cache upcall program"); | |
28 | module_param_named(cache_getent_timeout, nfs_cache_getent_timeout, ulong, 0600); | |
29 | MODULE_PARM_DESC(cache_getent_timeout, "Timeout (in seconds) after which " | |
30 | "the cache upcall is assumed to have failed"); | |
31 | ||
32 | int nfs_cache_upcall(struct cache_detail *cd, char *entry_name) | |
33 | { | |
34 | static char *envp[] = { "HOME=/", | |
35 | "TERM=linux", | |
36 | "PATH=/sbin:/usr/sbin:/bin:/usr/bin", | |
37 | NULL | |
38 | }; | |
39 | char *argv[] = { | |
40 | nfs_cache_getent_prog, | |
41 | cd->name, | |
42 | entry_name, | |
43 | NULL | |
44 | }; | |
45 | int ret = -EACCES; | |
46 | ||
47 | if (nfs_cache_getent_prog[0] == '\0') | |
48 | goto out; | |
49 | ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
50 | /* | |
51 | * Disable the upcall mechanism if we're getting an ENOENT or | |
52 | * EACCES error. The admin can re-enable it on the fly by using | |
53 | * sysfs to set the 'cache_getent' parameter once the problem | |
54 | * has been fixed. | |
55 | */ | |
56 | if (ret == -ENOENT || ret == -EACCES) | |
57 | nfs_cache_getent_prog[0] = '\0'; | |
58 | out: | |
59 | return ret > 0 ? 0 : ret; | |
60 | } | |
61 | ||
62 | /* | |
63 | * Deferred request handling | |
64 | */ | |
65 | void nfs_cache_defer_req_put(struct nfs_cache_defer_req *dreq) | |
66 | { | |
67 | if (atomic_dec_and_test(&dreq->count)) | |
68 | kfree(dreq); | |
69 | } | |
70 | ||
71 | static void nfs_dns_cache_revisit(struct cache_deferred_req *d, int toomany) | |
72 | { | |
73 | struct nfs_cache_defer_req *dreq; | |
74 | ||
75 | dreq = container_of(d, struct nfs_cache_defer_req, deferred_req); | |
76 | ||
77 | complete_all(&dreq->completion); | |
78 | nfs_cache_defer_req_put(dreq); | |
79 | } | |
80 | ||
81 | static struct cache_deferred_req *nfs_dns_cache_defer(struct cache_req *req) | |
82 | { | |
83 | struct nfs_cache_defer_req *dreq; | |
84 | ||
85 | dreq = container_of(req, struct nfs_cache_defer_req, req); | |
86 | dreq->deferred_req.revisit = nfs_dns_cache_revisit; | |
87 | atomic_inc(&dreq->count); | |
88 | ||
89 | return &dreq->deferred_req; | |
90 | } | |
91 | ||
92 | struct nfs_cache_defer_req *nfs_cache_defer_req_alloc(void) | |
93 | { | |
94 | struct nfs_cache_defer_req *dreq; | |
95 | ||
96 | dreq = kzalloc(sizeof(*dreq), GFP_KERNEL); | |
97 | if (dreq) { | |
98 | init_completion(&dreq->completion); | |
99 | atomic_set(&dreq->count, 1); | |
100 | dreq->req.defer = nfs_dns_cache_defer; | |
101 | } | |
102 | return dreq; | |
103 | } | |
104 | ||
105 | int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req *dreq) | |
106 | { | |
107 | if (wait_for_completion_timeout(&dreq->completion, | |
108 | nfs_cache_getent_timeout * HZ) == 0) | |
109 | return -ETIMEDOUT; | |
110 | return 0; | |
111 | } | |
112 | ||
113 | int nfs_cache_register(struct cache_detail *cd) | |
114 | { | |
115 | struct nameidata nd; | |
116 | struct vfsmount *mnt; | |
117 | int ret; | |
118 | ||
119 | mnt = rpc_get_mount(); | |
120 | if (IS_ERR(mnt)) | |
121 | return PTR_ERR(mnt); | |
122 | ret = vfs_path_lookup(mnt->mnt_root, mnt, "/cache", 0, &nd); | |
123 | if (ret) | |
124 | goto err; | |
125 | ret = sunrpc_cache_register_pipefs(nd.path.dentry, | |
126 | cd->name, 0600, cd); | |
127 | path_put(&nd.path); | |
128 | if (!ret) | |
129 | return ret; | |
130 | err: | |
131 | rpc_put_mount(); | |
132 | return ret; | |
133 | } | |
134 | ||
135 | void nfs_cache_unregister(struct cache_detail *cd) | |
136 | { | |
137 | sunrpc_cache_unregister_pipefs(cd); | |
138 | rpc_put_mount(); | |
139 | } | |
140 |