NFS: Allow redirtying of a completed unstable write.
[linux-2.6.git] / 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_serv *serv;
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         nfs_callback_info.task = NULL;
95         svc_exit_thread(rqstp);
96         return 0;
97 }
98
99 /*
100  * Bring up the server process if it is not already up.
101  */
102 int nfs_callback_up(void)
103 {
104         struct svc_serv *serv = NULL;
105         struct svc_rqst *rqstp;
106         int ret = 0;
107
108         lock_kernel();
109         mutex_lock(&nfs_callback_mutex);
110         if (nfs_callback_info.users++ || nfs_callback_info.task != NULL)
111                 goto out;
112         serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
113         ret = -ENOMEM;
114         if (!serv)
115                 goto out_err;
116
117         ret = svc_create_xprt(serv, "tcp", nfs_callback_set_tcpport,
118                               SVC_SOCK_ANONYMOUS);
119         if (ret <= 0)
120                 goto out_err;
121         nfs_callback_tcpport = ret;
122         dprintk("Callback port = 0x%x\n", nfs_callback_tcpport);
123
124         rqstp = svc_prepare_thread(serv, &serv->sv_pools[0]);
125         if (IS_ERR(rqstp)) {
126                 ret = PTR_ERR(rqstp);
127                 goto out_err;
128         }
129
130         svc_sock_update_bufs(serv);
131         nfs_callback_info.serv = serv;
132
133         nfs_callback_info.task = kthread_run(nfs_callback_svc, rqstp,
134                                              "nfsv4-svc");
135         if (IS_ERR(nfs_callback_info.task)) {
136                 ret = PTR_ERR(nfs_callback_info.task);
137                 nfs_callback_info.serv = NULL;
138                 nfs_callback_info.task = NULL;
139                 svc_exit_thread(rqstp);
140                 goto out_err;
141         }
142 out:
143         /*
144          * svc_create creates the svc_serv with sv_nrthreads == 1, and then
145          * svc_prepare_thread increments that. So we need to call svc_destroy
146          * on both success and failure so that the refcount is 1 when the
147          * thread exits.
148          */
149         if (serv)
150                 svc_destroy(serv);
151         mutex_unlock(&nfs_callback_mutex);
152         unlock_kernel();
153         return ret;
154 out_err:
155         dprintk("Couldn't create callback socket or server thread; err = %d\n",
156                 ret);
157         nfs_callback_info.users--;
158         goto out;
159 }
160
161 /*
162  * Kill the server process if it is not already down.
163  */
164 void nfs_callback_down(void)
165 {
166         lock_kernel();
167         mutex_lock(&nfs_callback_mutex);
168         nfs_callback_info.users--;
169         if (nfs_callback_info.users == 0 && nfs_callback_info.task != NULL)
170                 kthread_stop(nfs_callback_info.task);
171         mutex_unlock(&nfs_callback_mutex);
172         unlock_kernel();
173 }
174
175 static int nfs_callback_authenticate(struct svc_rqst *rqstp)
176 {
177         struct nfs_client *clp;
178         RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
179
180         /* Don't talk to strangers */
181         clp = nfs_find_client(svc_addr(rqstp), 4);
182         if (clp == NULL)
183                 return SVC_DROP;
184
185         dprintk("%s: %s NFSv4 callback!\n", __func__,
186                         svc_print_addr(rqstp, buf, sizeof(buf)));
187         nfs_put_client(clp);
188
189         switch (rqstp->rq_authop->flavour) {
190                 case RPC_AUTH_NULL:
191                         if (rqstp->rq_proc != CB_NULL)
192                                 return SVC_DENIED;
193                         break;
194                 case RPC_AUTH_UNIX:
195                         break;
196                 case RPC_AUTH_GSS:
197                         /* FIXME: RPCSEC_GSS handling? */
198                 default:
199                         return SVC_DENIED;
200         }
201         return SVC_OK;
202 }
203
204 /*
205  * Define NFS4 callback program
206  */
207 static struct svc_version *nfs4_callback_version[] = {
208         [1] = &nfs4_callback_version1,
209 };
210
211 static struct svc_stat nfs4_callback_stats;
212
213 static struct svc_program nfs4_callback_program = {
214         .pg_prog = NFS4_CALLBACK,                       /* RPC service number */
215         .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
216         .pg_vers = nfs4_callback_version,               /* version table */
217         .pg_name = "NFSv4 callback",                    /* service name */
218         .pg_class = "nfs",                              /* authentication class */
219         .pg_stats = &nfs4_callback_stats,
220         .pg_authenticate = nfs_callback_authenticate,
221 };