NFS: Remove BKL usage from the write path
[linux-2.6] / fs / nfs / callback.c
1 /*
2  * linux/fs/nfs/callback.c
3  *
4  * Copyright (C) 2004 Trond Myklebust
5  *
6  * NFSv4 callback handling
7  */
8
9 #include <linux/completion.h>
10 #include <linux/ip.h>
11 #include <linux/module.h>
12 #include <linux/smp_lock.h>
13 #include <linux/sunrpc/svc.h>
14 #include <linux/sunrpc/svcsock.h>
15 #include <linux/nfs_fs.h>
16 #include <linux/mutex.h>
17 #include <linux/freezer.h>
18 #include <linux/kthread.h>
19
20 #include <net/inet_sock.h>
21
22 #include "nfs4_fs.h"
23 #include "callback.h"
24 #include "internal.h"
25
26 #define NFSDBG_FACILITY NFSDBG_CALLBACK
27
28 struct nfs_callback_data {
29         unsigned int users;
30         struct svc_rqst *rqst;
31         struct task_struct *task;
32 };
33
34 static struct nfs_callback_data nfs_callback_info;
35 static DEFINE_MUTEX(nfs_callback_mutex);
36 static struct svc_program nfs4_callback_program;
37
38 unsigned int nfs_callback_set_tcpport;
39 unsigned short nfs_callback_tcpport;
40 static const int nfs_set_port_min = 0;
41 static const int nfs_set_port_max = 65535;
42
43 static int param_set_port(const char *val, struct kernel_param *kp)
44 {
45         char *endp;
46         int num = simple_strtol(val, &endp, 0);
47         if (endp == val || *endp || num < nfs_set_port_min || num > nfs_set_port_max)
48                 return -EINVAL;
49         *((int *)kp->arg) = num;
50         return 0;
51 }
52
53 module_param_call(callback_tcpport, param_set_port, param_get_int,
54                  &nfs_callback_set_tcpport, 0644);
55
56 /*
57  * This is the callback kernel thread.
58  */
59 static int
60 nfs_callback_svc(void *vrqstp)
61 {
62         int err, preverr = 0;
63         struct svc_rqst *rqstp = vrqstp;
64
65         set_freezable();
66
67         /*
68          * FIXME: do we really need to run this under the BKL? If so, please
69          * add a comment about what it's intended to protect.
70          */
71         lock_kernel();
72         while (!kthread_should_stop()) {
73                 /*
74                  * Listen for a request on the socket
75                  */
76                 err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
77                 if (err == -EAGAIN || err == -EINTR) {
78                         preverr = err;
79                         continue;
80                 }
81                 if (err < 0) {
82                         if (err != preverr) {
83                                 printk(KERN_WARNING "%s: unexpected error "
84                                         "from svc_recv (%d)\n", __func__, err);
85                                 preverr = err;
86                         }
87                         schedule_timeout_uninterruptible(HZ);
88                         continue;
89                 }
90                 preverr = err;
91                 svc_process(rqstp);
92         }
93         unlock_kernel();
94         return 0;
95 }
96
97 /*
98  * Bring up the callback thread if it is not already up.
99  */
100 int nfs_callback_up(void)
101 {
102         struct svc_serv *serv = NULL;
103         int ret = 0;
104
105         mutex_lock(&nfs_callback_mutex);
106         if (nfs_callback_info.users++ || nfs_callback_info.task != NULL)
107                 goto out;
108         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
109         ret = -ENOMEM;
110         if (!serv)
111                 goto out_err;
112
113         ret = svc_create_xprt(serv, "tcp", nfs_callback_set_tcpport,
114                               SVC_SOCK_ANONYMOUS);
115         if (ret <= 0)
116                 goto out_err;
117         nfs_callback_tcpport = ret;
118         dprintk("Callback port = 0x%x\n", nfs_callback_tcpport);
119
120         nfs_callback_info.rqst = svc_prepare_thread(serv, &serv->sv_pools[0]);
121         if (IS_ERR(nfs_callback_info.rqst)) {
122                 ret = PTR_ERR(nfs_callback_info.rqst);
123                 nfs_callback_info.rqst = NULL;
124                 goto out_err;
125         }
126
127         svc_sock_update_bufs(serv);
128
129         nfs_callback_info.task = kthread_run(nfs_callback_svc,
130                                              nfs_callback_info.rqst,
131                                              "nfsv4-svc");
132         if (IS_ERR(nfs_callback_info.task)) {
133                 ret = PTR_ERR(nfs_callback_info.task);
134                 svc_exit_thread(nfs_callback_info.rqst);
135                 nfs_callback_info.rqst = NULL;
136                 nfs_callback_info.task = NULL;
137                 goto out_err;
138         }
139 out:
140         /*
141          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
142          * svc_prepare_thread increments that. So we need to call svc_destroy
143          * on both success and failure so that the refcount is 1 when the
144          * thread exits.
145          */
146         if (serv)
147                 svc_destroy(serv);
148         mutex_unlock(&nfs_callback_mutex);
149         return ret;
150 out_err:
151         dprintk("Couldn't create callback socket or server thread; err = %d\n",
152                 ret);
153         nfs_callback_info.users--;
154         goto out;
155 }
156
157 /*
158  * Kill the callback thread if it's no longer being used.
159  */
160 void nfs_callback_down(void)
161 {
162         mutex_lock(&nfs_callback_mutex);
163         nfs_callback_info.users--;
164         if (nfs_callback_info.users == 0 && nfs_callback_info.task != NULL) {
165                 kthread_stop(nfs_callback_info.task);
166                 svc_exit_thread(nfs_callback_info.rqst);
167                 nfs_callback_info.rqst = NULL;
168                 nfs_callback_info.task = NULL;
169         }
170         mutex_unlock(&nfs_callback_mutex);
171 }
172
173 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
174 {
175         struct nfs_client *clp;
176         RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
177
178         /* Don't talk to strangers */
179         clp = nfs_find_client(svc_addr(rqstp), 4);
180         if (clp == NULL)
181                 return SVC_DROP;
182
183         dprintk("%s: %s NFSv4 callback!\n", __func__,
184                         svc_print_addr(rqstp, buf, sizeof(buf)));
185         nfs_put_client(clp);
186
187         switch (rqstp->rq_authop->flavour) {
188                 case RPC_AUTH_NULL:
189                         if (rqstp->rq_proc != CB_NULL)
190                                 return SVC_DENIED;
191                         break;
192                 case RPC_AUTH_UNIX:
193                         break;
194                 case RPC_AUTH_GSS:
195                         /* FIXME: RPCSEC_GSS handling? */
196                 default:
197                         return SVC_DENIED;
198         }
199         return SVC_OK;
200 }
201
202 /*
203  * Define NFS4 callback program
204  */
205 static struct svc_version *nfs4_callback_version[] = {
206         [1] = &nfs4_callback_version1,
207 };
208
209 static struct svc_stat nfs4_callback_stats;
210
211 static struct svc_program nfs4_callback_program = {
212         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
213         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
214         .pg_vers = nfs4_callback_version,               /* version table */
215         .pg_name = "NFSv4 callback",                    /* service name */
216         .pg_class = "nfs",                              /* authentication class */
217         .pg_stats = &nfs4_callback_stats,
218         .pg_authenticate = nfs_callback_authenticate,
219 };