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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> | |
5a0e3ad6 | 13 | #include <linux/slab.h> |
e571cbf1 TM |
14 | #include <linux/sunrpc/cache.h> |
15 | #include <linux/sunrpc/rpc_pipe_fs.h> | |
16 | ||
17 | #include "cache_lib.h" | |
18 | ||
19 | #define NFS_CACHE_UPCALL_PATHLEN 256 | |
20 | #define NFS_CACHE_UPCALL_TIMEOUT 15 | |
21 | ||
22 | static char nfs_cache_getent_prog[NFS_CACHE_UPCALL_PATHLEN] = | |
23 | "/sbin/nfs_cache_getent"; | |
24 | static unsigned long nfs_cache_getent_timeout = NFS_CACHE_UPCALL_TIMEOUT; | |
25 | ||
26 | module_param_string(cache_getent, nfs_cache_getent_prog, | |
27 | sizeof(nfs_cache_getent_prog), 0600); | |
28 | MODULE_PARM_DESC(cache_getent, "Path to the client cache upcall program"); | |
29 | module_param_named(cache_getent_timeout, nfs_cache_getent_timeout, ulong, 0600); | |
30 | MODULE_PARM_DESC(cache_getent_timeout, "Timeout (in seconds) after which " | |
31 | "the cache upcall is assumed to have failed"); | |
32 | ||
33 | int nfs_cache_upcall(struct cache_detail *cd, char *entry_name) | |
34 | { | |
35 | static char *envp[] = { "HOME=/", | |
36 | "TERM=linux", | |
37 | "PATH=/sbin:/usr/sbin:/bin:/usr/bin", | |
38 | NULL | |
39 | }; | |
40 | char *argv[] = { | |
41 | nfs_cache_getent_prog, | |
42 | cd->name, | |
43 | entry_name, | |
44 | NULL | |
45 | }; | |
46 | int ret = -EACCES; | |
47 | ||
48 | if (nfs_cache_getent_prog[0] == '\0') | |
49 | goto out; | |
50 | ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
51 | /* | |
52 | * Disable the upcall mechanism if we're getting an ENOENT or | |
53 | * EACCES error. The admin can re-enable it on the fly by using | |
54 | * sysfs to set the 'cache_getent' parameter once the problem | |
55 | * has been fixed. | |
56 | */ | |
57 | if (ret == -ENOENT || ret == -EACCES) | |
58 | nfs_cache_getent_prog[0] = '\0'; | |
59 | out: | |
60 | return ret > 0 ? 0 : ret; | |
61 | } | |
62 | ||
63 | /* | |
64 | * Deferred request handling | |
65 | */ | |
66 | void nfs_cache_defer_req_put(struct nfs_cache_defer_req *dreq) | |
67 | { | |
68 | if (atomic_dec_and_test(&dreq->count)) | |
69 | kfree(dreq); | |
70 | } | |
71 | ||
72 | static void nfs_dns_cache_revisit(struct cache_deferred_req *d, int toomany) | |
73 | { | |
74 | struct nfs_cache_defer_req *dreq; | |
75 | ||
76 | dreq = container_of(d, struct nfs_cache_defer_req, deferred_req); | |
77 | ||
78 | complete_all(&dreq->completion); | |
79 | nfs_cache_defer_req_put(dreq); | |
80 | } | |
81 | ||
82 | static struct cache_deferred_req *nfs_dns_cache_defer(struct cache_req *req) | |
83 | { | |
84 | struct nfs_cache_defer_req *dreq; | |
85 | ||
86 | dreq = container_of(req, struct nfs_cache_defer_req, req); | |
87 | dreq->deferred_req.revisit = nfs_dns_cache_revisit; | |
88 | atomic_inc(&dreq->count); | |
89 | ||
90 | return &dreq->deferred_req; | |
91 | } | |
92 | ||
93 | struct nfs_cache_defer_req *nfs_cache_defer_req_alloc(void) | |
94 | { | |
95 | struct nfs_cache_defer_req *dreq; | |
96 | ||
97 | dreq = kzalloc(sizeof(*dreq), GFP_KERNEL); | |
98 | if (dreq) { | |
99 | init_completion(&dreq->completion); | |
100 | atomic_set(&dreq->count, 1); | |
101 | dreq->req.defer = nfs_dns_cache_defer; | |
102 | } | |
103 | return dreq; | |
104 | } | |
105 | ||
106 | int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req *dreq) | |
107 | { | |
108 | if (wait_for_completion_timeout(&dreq->completion, | |
109 | nfs_cache_getent_timeout * HZ) == 0) | |
110 | return -ETIMEDOUT; | |
111 | return 0; | |
112 | } | |
113 | ||
114 | int nfs_cache_register(struct cache_detail *cd) | |
115 | { | |
116 | struct nameidata nd; | |
117 | struct vfsmount *mnt; | |
118 | int ret; | |
119 | ||
120 | mnt = rpc_get_mount(); | |
121 | if (IS_ERR(mnt)) | |
122 | return PTR_ERR(mnt); | |
123 | ret = vfs_path_lookup(mnt->mnt_root, mnt, "/cache", 0, &nd); | |
124 | if (ret) | |
125 | goto err; | |
126 | ret = sunrpc_cache_register_pipefs(nd.path.dentry, | |
127 | cd->name, 0600, cd); | |
128 | path_put(&nd.path); | |
129 | if (!ret) | |
130 | return ret; | |
131 | err: | |
132 | rpc_put_mount(); | |
133 | return ret; | |
134 | } | |
135 | ||
136 | void nfs_cache_unregister(struct cache_detail *cd) | |
137 | { | |
138 | sunrpc_cache_unregister_pipefs(cd); | |
139 | rpc_put_mount(); | |
140 | } | |
141 |