[PATCH] knfsd: lockd: introduce nsm_handle
[linux-2.6.git] / fs / lockd / clntlock.c
1 /*
2  * linux/fs/lockd/clntlock.c
3  *
4  * Lock handling for the client side NLM implementation
5  *
6  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
7  */
8
9 #include <linux/module.h>
10 #include <linux/types.h>
11 #include <linux/time.h>
12 #include <linux/nfs_fs.h>
13 #include <linux/sunrpc/clnt.h>
14 #include <linux/sunrpc/svc.h>
15 #include <linux/lockd/lockd.h>
16 #include <linux/smp_lock.h>
17
18 #define NLMDBG_FACILITY         NLMDBG_CLIENT
19
20 /*
21  * Local function prototypes
22  */
23 static int                      reclaimer(void *ptr);
24
25 /*
26  * The following functions handle blocking and granting from the
27  * client perspective.
28  */
29
30 /*
31  * This is the representation of a blocked client lock.
32  */
33 struct nlm_wait {
34         struct list_head        b_list;         /* linked list */
35         wait_queue_head_t       b_wait;         /* where to wait on */
36         struct nlm_host *       b_host;
37         struct file_lock *      b_lock;         /* local file lock */
38         unsigned short          b_reclaim;      /* got to reclaim lock */
39         u32                     b_status;       /* grant callback status */
40 };
41
42 static LIST_HEAD(nlm_blocked);
43
44 /*
45  * Queue up a lock for blocking so that the GRANTED request can see it
46  */
47 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
48 {
49         struct nlm_wait *block;
50
51         block = kmalloc(sizeof(*block), GFP_KERNEL);
52         if (block != NULL) {
53                 block->b_host = host;
54                 block->b_lock = fl;
55                 init_waitqueue_head(&block->b_wait);
56                 block->b_status = NLM_LCK_BLOCKED;
57                 list_add(&block->b_list, &nlm_blocked);
58         }
59         return block;
60 }
61
62 void nlmclnt_finish_block(struct nlm_wait *block)
63 {
64         if (block == NULL)
65                 return;
66         list_del(&block->b_list);
67         kfree(block);
68 }
69
70 /*
71  * Block on a lock
72  */
73 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
74 {
75         long ret;
76
77         /* A borken server might ask us to block even if we didn't
78          * request it. Just say no!
79          */
80         if (block == NULL)
81                 return -EAGAIN;
82
83         /* Go to sleep waiting for GRANT callback. Some servers seem
84          * to lose callbacks, however, so we're going to poll from
85          * time to time just to make sure.
86          *
87          * For now, the retry frequency is pretty high; normally 
88          * a 1 minute timeout would do. See the comment before
89          * nlmclnt_lock for an explanation.
90          */
91         ret = wait_event_interruptible_timeout(block->b_wait,
92                         block->b_status != NLM_LCK_BLOCKED,
93                         timeout);
94         if (ret < 0)
95                 return -ERESTARTSYS;
96         req->a_res.status = block->b_status;
97         return 0;
98 }
99
100 /*
101  * The server lockd has called us back to tell us the lock was granted
102  */
103 u32 nlmclnt_grant(const struct sockaddr_in *addr, const struct nlm_lock *lock)
104 {
105         const struct file_lock *fl = &lock->fl;
106         const struct nfs_fh *fh = &lock->fh;
107         struct nlm_wait *block;
108         u32 res = nlm_lck_denied;
109
110         /*
111          * Look up blocked request based on arguments. 
112          * Warning: must not use cookie to match it!
113          */
114         list_for_each_entry(block, &nlm_blocked, b_list) {
115                 struct file_lock *fl_blocked = block->b_lock;
116
117                 if (fl_blocked->fl_start != fl->fl_start)
118                         continue;
119                 if (fl_blocked->fl_end != fl->fl_end)
120                         continue;
121                 /*
122                  * Careful! The NLM server will return the 32-bit "pid" that
123                  * we put on the wire: in this case the lockowner "pid".
124                  */
125                 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
126                         continue;
127                 if (!nlm_cmp_addr(&block->b_host->h_addr, addr))
128                         continue;
129                 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_dentry->d_inode) ,fh) != 0)
130                         continue;
131                 /* Alright, we found a lock. Set the return status
132                  * and wake up the caller
133                  */
134                 block->b_status = NLM_LCK_GRANTED;
135                 wake_up(&block->b_wait);
136                 res = nlm_granted;
137         }
138         return res;
139 }
140
141 /*
142  * The following procedures deal with the recovery of locks after a
143  * server crash.
144  */
145
146 /*
147  * Someone has sent us an SM_NOTIFY. Ensure we bind to the new port number,
148  * that we mark locks for reclaiming, and that we bump the pseudo NSM state.
149  */
150 static void nlmclnt_prepare_reclaim(struct nlm_host *host)
151 {
152         down_write(&host->h_rwsem);
153         if (host->h_nsmhandle)
154                 host->h_nsmhandle->sm_monitored = 0;
155         host->h_state++;
156         host->h_nextrebind = 0;
157         nlm_rebind_host(host);
158
159         /*
160          * Mark the locks for reclaiming.
161          */
162         list_splice_init(&host->h_granted, &host->h_reclaim);
163
164         dprintk("NLM: reclaiming locks for host %s\n", host->h_name);
165 }
166
167 static void nlmclnt_finish_reclaim(struct nlm_host *host)
168 {
169         host->h_reclaiming = 0;
170         up_write(&host->h_rwsem);
171         dprintk("NLM: done reclaiming locks for host %s", host->h_name);
172 }
173
174 /*
175  * Reclaim all locks on server host. We do this by spawning a separate
176  * reclaimer thread.
177  */
178 void
179 nlmclnt_recovery(struct nlm_host *host, u32 newstate)
180 {
181         if (host->h_nsmstate == newstate)
182                 return;
183         host->h_nsmstate = newstate;
184         if (!host->h_reclaiming++) {
185                 nlm_get_host(host);
186                 __module_get(THIS_MODULE);
187                 if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0)
188                         module_put(THIS_MODULE);
189         }
190 }
191
192 static int
193 reclaimer(void *ptr)
194 {
195         struct nlm_host   *host = (struct nlm_host *) ptr;
196         struct nlm_wait   *block;
197         struct file_lock *fl, *next;
198         u32 nsmstate;
199
200         daemonize("%s-reclaim", host->h_name);
201         allow_signal(SIGKILL);
202
203         /* This one ensures that our parent doesn't terminate while the
204          * reclaim is in progress */
205         lock_kernel();
206         lockd_up(0); /* note: this cannot fail as lockd is already running */
207
208         nlmclnt_prepare_reclaim(host);
209         /* First, reclaim all locks that have been marked. */
210 restart:
211         nsmstate = host->h_nsmstate;
212         list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
213                 list_del_init(&fl->fl_u.nfs_fl.list);
214
215                 if (signalled())
216                         continue;
217                 if (nlmclnt_reclaim(host, fl) != 0)
218                         continue;
219                 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
220                 if (host->h_nsmstate != nsmstate) {
221                         /* Argh! The server rebooted again! */
222                         list_splice_init(&host->h_granted, &host->h_reclaim);
223                         goto restart;
224                 }
225         }
226         nlmclnt_finish_reclaim(host);
227
228         /* Now, wake up all processes that sleep on a blocked lock */
229         list_for_each_entry(block, &nlm_blocked, b_list) {
230                 if (block->b_host == host) {
231                         block->b_status = NLM_LCK_DENIED_GRACE_PERIOD;
232                         wake_up(&block->b_wait);
233                 }
234         }
235
236         /* Release host handle after use */
237         nlm_release_host(host);
238         lockd_down();
239         unlock_kernel();
240         module_put_and_exit(0);
241 }