1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * linux/fs/nfs/cache_lib.c |
4 | * |
5 | * Helper routines for the NFS client caches |
6 | * |
7 | * Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com> |
8 | */ |
9 | #include <linux/kmod.h> |
10 | #include <linux/module.h> |
11 | #include <linux/moduleparam.h> |
12 | #include <linux/mount.h> |
13 | #include <linux/namei.h> |
14 | #include <linux/slab.h> |
15 | #include <linux/sunrpc/cache.h> |
16 | #include <linux/sunrpc/rpc_pipe_fs.h> |
17 | #include <net/net_namespace.h> |
18 | |
19 | #include "cache_lib.h" |
20 | |
21 | #define NFS_CACHE_UPCALL_PATHLEN 256 |
22 | #define NFS_CACHE_UPCALL_TIMEOUT 15 |
23 | |
24 | static char nfs_cache_getent_prog[NFS_CACHE_UPCALL_PATHLEN] = |
25 | "/sbin/nfs_cache_getent" ; |
26 | static unsigned long nfs_cache_getent_timeout = NFS_CACHE_UPCALL_TIMEOUT; |
27 | |
28 | module_param_string(cache_getent, nfs_cache_getent_prog, |
29 | sizeof(nfs_cache_getent_prog), 0600); |
30 | MODULE_PARM_DESC(cache_getent, "Path to the client cache upcall program" ); |
31 | module_param_named(cache_getent_timeout, nfs_cache_getent_timeout, ulong, 0600); |
32 | MODULE_PARM_DESC(cache_getent_timeout, "Timeout (in seconds) after which " |
33 | "the cache upcall is assumed to have failed" ); |
34 | |
35 | int nfs_cache_upcall(struct cache_detail *cd, char *entry_name) |
36 | { |
37 | static char *envp[] = { "HOME=/" , |
38 | "TERM=linux" , |
39 | "PATH=/sbin:/usr/sbin:/bin:/usr/bin" , |
40 | NULL |
41 | }; |
42 | char *argv[] = { |
43 | nfs_cache_getent_prog, |
44 | cd->name, |
45 | entry_name, |
46 | NULL |
47 | }; |
48 | int ret = -EACCES; |
49 | |
50 | if (nfs_cache_getent_prog[0] == '\0') |
51 | goto out; |
52 | ret = call_usermodehelper(path: argv[0], argv, envp, UMH_WAIT_EXEC); |
53 | /* |
54 | * Disable the upcall mechanism if we're getting an ENOENT or |
55 | * EACCES error. The admin can re-enable it on the fly by using |
56 | * sysfs to set the 'cache_getent' parameter once the problem |
57 | * has been fixed. |
58 | */ |
59 | if (ret == -ENOENT || ret == -EACCES) |
60 | nfs_cache_getent_prog[0] = '\0'; |
61 | out: |
62 | return ret > 0 ? 0 : ret; |
63 | } |
64 | |
65 | /* |
66 | * Deferred request handling |
67 | */ |
68 | void nfs_cache_defer_req_put(struct nfs_cache_defer_req *dreq) |
69 | { |
70 | if (refcount_dec_and_test(r: &dreq->count)) |
71 | kfree(objp: dreq); |
72 | } |
73 | |
74 | static void nfs_dns_cache_revisit(struct cache_deferred_req *d, int toomany) |
75 | { |
76 | struct nfs_cache_defer_req *dreq; |
77 | |
78 | dreq = container_of(d, struct nfs_cache_defer_req, deferred_req); |
79 | |
80 | complete(&dreq->completion); |
81 | nfs_cache_defer_req_put(dreq); |
82 | } |
83 | |
84 | static struct cache_deferred_req *nfs_dns_cache_defer(struct cache_req *req) |
85 | { |
86 | struct nfs_cache_defer_req *dreq; |
87 | |
88 | dreq = container_of(req, struct nfs_cache_defer_req, req); |
89 | dreq->deferred_req.revisit = nfs_dns_cache_revisit; |
90 | refcount_inc(r: &dreq->count); |
91 | |
92 | return &dreq->deferred_req; |
93 | } |
94 | |
95 | struct nfs_cache_defer_req *nfs_cache_defer_req_alloc(void) |
96 | { |
97 | struct nfs_cache_defer_req *dreq; |
98 | |
99 | dreq = kzalloc(size: sizeof(*dreq), GFP_KERNEL); |
100 | if (dreq) { |
101 | init_completion(x: &dreq->completion); |
102 | refcount_set(r: &dreq->count, n: 1); |
103 | dreq->req.defer = nfs_dns_cache_defer; |
104 | } |
105 | return dreq; |
106 | } |
107 | |
108 | int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req *dreq) |
109 | { |
110 | if (wait_for_completion_timeout(x: &dreq->completion, |
111 | timeout: nfs_cache_getent_timeout * HZ) == 0) |
112 | return -ETIMEDOUT; |
113 | return 0; |
114 | } |
115 | |
116 | int nfs_cache_register_sb(struct super_block *sb, struct cache_detail *cd) |
117 | { |
118 | int ret; |
119 | struct dentry *dir; |
120 | |
121 | dir = rpc_d_lookup_sb(sb, dir_name: "cache" ); |
122 | ret = sunrpc_cache_register_pipefs(parent: dir, cd->name, 0600, cd); |
123 | dput(dir); |
124 | return ret; |
125 | } |
126 | |
127 | int nfs_cache_register_net(struct net *net, struct cache_detail *cd) |
128 | { |
129 | struct super_block *pipefs_sb; |
130 | int ret = 0; |
131 | |
132 | sunrpc_init_cache_detail(cd); |
133 | pipefs_sb = rpc_get_sb_net(net); |
134 | if (pipefs_sb) { |
135 | ret = nfs_cache_register_sb(sb: pipefs_sb, cd); |
136 | rpc_put_sb_net(net); |
137 | if (ret) |
138 | sunrpc_destroy_cache_detail(cd); |
139 | } |
140 | return ret; |
141 | } |
142 | |
143 | void nfs_cache_unregister_sb(struct super_block *sb, struct cache_detail *cd) |
144 | { |
145 | sunrpc_cache_unregister_pipefs(cd); |
146 | } |
147 | |
148 | void nfs_cache_unregister_net(struct net *net, struct cache_detail *cd) |
149 | { |
150 | struct super_block *pipefs_sb; |
151 | |
152 | pipefs_sb = rpc_get_sb_net(net); |
153 | if (pipefs_sb) { |
154 | nfs_cache_unregister_sb(sb: pipefs_sb, cd); |
155 | rpc_put_sb_net(net); |
156 | } |
157 | sunrpc_destroy_cache_detail(cd); |
158 | } |
159 | |