blob: b4ffd0146ea61cb2c4ff80fa098d7f1a45200976 [file] [log] [blame]
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001/*
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
21static char nfs_cache_getent_prog[NFS_CACHE_UPCALL_PATHLEN] =
22 "/sbin/nfs_cache_getent";
23static unsigned long nfs_cache_getent_timeout = NFS_CACHE_UPCALL_TIMEOUT;
24
25module_param_string(cache_getent, nfs_cache_getent_prog,
26 sizeof(nfs_cache_getent_prog), 0600);
27MODULE_PARM_DESC(cache_getent, "Path to the client cache upcall program");
28module_param_named(cache_getent_timeout, nfs_cache_getent_timeout, ulong, 0600);
29MODULE_PARM_DESC(cache_getent_timeout, "Timeout (in seconds) after which "
30 "the cache upcall is assumed to have failed");
31
32int 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';
58out:
59 return ret > 0 ? 0 : ret;
60}
61
62/*
63 * Deferred request handling
64 */
65void 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
71static 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
81static 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
92struct 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
105int 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
113int 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;
130err:
131 rpc_put_mount();
132 return ret;
133}
134
135void nfs_cache_unregister(struct cache_detail *cd)
136{
137 sunrpc_cache_unregister_pipefs(cd);
138 rpc_put_mount();
139}
140