NLM: Fix reclaim races
[linux-2.6.git] / fs / lockd / clntproc.c
1 /*
2  * linux/fs/lockd/clntproc.c
3  *
4  * RPC procedures for the client side NLM implementation
5  *
6  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
7  */
8
9 #include <linux/config.h>
10 #include <linux/module.h>
11 #include <linux/types.h>
12 #include <linux/errno.h>
13 #include <linux/fs.h>
14 #include <linux/nfs_fs.h>
15 #include <linux/utsname.h>
16 #include <linux/smp_lock.h>
17 #include <linux/sunrpc/clnt.h>
18 #include <linux/sunrpc/svc.h>
19 #include <linux/lockd/lockd.h>
20 #include <linux/lockd/sm_inter.h>
21
22 #define NLMDBG_FACILITY         NLMDBG_CLIENT
23 #define NLMCLNT_GRACE_WAIT      (5*HZ)
24 #define NLMCLNT_POLL_TIMEOUT    (30*HZ)
25 #define NLMCLNT_MAX_RETRIES     3
26
27 static int      nlmclnt_test(struct nlm_rqst *, struct file_lock *);
28 static int      nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
29 static int      nlmclnt_unlock(struct nlm_rqst *, struct file_lock *);
30 static int      nlm_stat_to_errno(u32 stat);
31 static void     nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host);
32 static int      nlmclnt_cancel(struct nlm_host *, int , struct file_lock *);
33
34 static const struct rpc_call_ops nlmclnt_unlock_ops;
35 static const struct rpc_call_ops nlmclnt_cancel_ops;
36
37 /*
38  * Cookie counter for NLM requests
39  */
40 static u32      nlm_cookie = 0x1234;
41
42 static inline void nlmclnt_next_cookie(struct nlm_cookie *c)
43 {
44         memcpy(c->data, &nlm_cookie, 4);
45         memset(c->data+4, 0, 4);
46         c->len=4;
47         nlm_cookie++;
48 }
49
50 static struct nlm_lockowner *nlm_get_lockowner(struct nlm_lockowner *lockowner)
51 {
52         atomic_inc(&lockowner->count);
53         return lockowner;
54 }
55
56 static void nlm_put_lockowner(struct nlm_lockowner *lockowner)
57 {
58         if (!atomic_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
59                 return;
60         list_del(&lockowner->list);
61         spin_unlock(&lockowner->host->h_lock);
62         nlm_release_host(lockowner->host);
63         kfree(lockowner);
64 }
65
66 static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
67 {
68         struct nlm_lockowner *lockowner;
69         list_for_each_entry(lockowner, &host->h_lockowners, list) {
70                 if (lockowner->pid == pid)
71                         return -EBUSY;
72         }
73         return 0;
74 }
75
76 static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
77 {
78         uint32_t res;
79         do {
80                 res = host->h_pidcount++;
81         } while (nlm_pidbusy(host, res) < 0);
82         return res;
83 }
84
85 static struct nlm_lockowner *__nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
86 {
87         struct nlm_lockowner *lockowner;
88         list_for_each_entry(lockowner, &host->h_lockowners, list) {
89                 if (lockowner->owner != owner)
90                         continue;
91                 return nlm_get_lockowner(lockowner);
92         }
93         return NULL;
94 }
95
96 static struct nlm_lockowner *nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
97 {
98         struct nlm_lockowner *res, *new = NULL;
99
100         spin_lock(&host->h_lock);
101         res = __nlm_find_lockowner(host, owner);
102         if (res == NULL) {
103                 spin_unlock(&host->h_lock);
104                 new = (struct nlm_lockowner *)kmalloc(sizeof(*new), GFP_KERNEL);
105                 spin_lock(&host->h_lock);
106                 res = __nlm_find_lockowner(host, owner);
107                 if (res == NULL && new != NULL) {
108                         res = new;
109                         atomic_set(&new->count, 1);
110                         new->owner = owner;
111                         new->pid = __nlm_alloc_pid(host);
112                         new->host = nlm_get_host(host);
113                         list_add(&new->list, &host->h_lockowners);
114                         new = NULL;
115                 }
116         }
117         spin_unlock(&host->h_lock);
118         kfree(new);
119         return res;
120 }
121
122 /*
123  * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
124  */
125 static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
126 {
127         struct nlm_args *argp = &req->a_args;
128         struct nlm_lock *lock = &argp->lock;
129
130         nlmclnt_next_cookie(&argp->cookie);
131         argp->state   = nsm_local_state;
132         memcpy(&lock->fh, NFS_FH(fl->fl_file->f_dentry->d_inode), sizeof(struct nfs_fh));
133         lock->caller  = system_utsname.nodename;
134         lock->oh.data = req->a_owner;
135         lock->oh.len  = snprintf(req->a_owner, sizeof(req->a_owner), "%u@%s",
136                                 (unsigned int)fl->fl_u.nfs_fl.owner->pid,
137                                 system_utsname.nodename);
138         lock->svid = fl->fl_u.nfs_fl.owner->pid;
139         lock->fl.fl_start = fl->fl_start;
140         lock->fl.fl_end = fl->fl_end;
141         lock->fl.fl_type = fl->fl_type;
142 }
143
144 static void nlmclnt_release_lockargs(struct nlm_rqst *req)
145 {
146         BUG_ON(req->a_args.lock.fl.fl_ops != NULL);
147 }
148
149 /*
150  * This is the main entry point for the NLM client.
151  */
152 int
153 nlmclnt_proc(struct inode *inode, int cmd, struct file_lock *fl)
154 {
155         struct nlm_host         *host;
156         struct nlm_rqst         *call;
157         sigset_t                oldset;
158         unsigned long           flags;
159         int                     status, proto, vers;
160
161         vers = (NFS_PROTO(inode)->version == 3) ? 4 : 1;
162         if (NFS_PROTO(inode)->version > 3) {
163                 printk(KERN_NOTICE "NFSv4 file locking not implemented!\n");
164                 return -ENOLCK;
165         }
166
167         /* Retrieve transport protocol from NFS client */
168         proto = NFS_CLIENT(inode)->cl_xprt->prot;
169
170         host = nlmclnt_lookup_host(NFS_ADDR(inode), proto, vers);
171         if (host == NULL)
172                 return -ENOLCK;
173
174         call = nlm_alloc_call(host);
175         if (call == NULL)
176                 return -ENOMEM;
177
178         nlmclnt_locks_init_private(fl, host);
179         /* Set up the argument struct */
180         nlmclnt_setlockargs(call, fl);
181
182         /* Keep the old signal mask */
183         spin_lock_irqsave(&current->sighand->siglock, flags);
184         oldset = current->blocked;
185
186         /* If we're cleaning up locks because the process is exiting,
187          * perform the RPC call asynchronously. */
188         if ((IS_SETLK(cmd) || IS_SETLKW(cmd))
189             && fl->fl_type == F_UNLCK
190             && (current->flags & PF_EXITING)) {
191                 sigfillset(&current->blocked);  /* Mask all signals */
192                 recalc_sigpending();
193
194                 call->a_flags = RPC_TASK_ASYNC;
195         }
196         spin_unlock_irqrestore(&current->sighand->siglock, flags);
197
198         if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
199                 if (fl->fl_type != F_UNLCK) {
200                         call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
201                         status = nlmclnt_lock(call, fl);
202                 } else
203                         status = nlmclnt_unlock(call, fl);
204         } else if (IS_GETLK(cmd))
205                 status = nlmclnt_test(call, fl);
206         else
207                 status = -EINVAL;
208
209         fl->fl_ops->fl_release_private(fl);
210         fl->fl_ops = NULL;
211
212         spin_lock_irqsave(&current->sighand->siglock, flags);
213         current->blocked = oldset;
214         recalc_sigpending();
215         spin_unlock_irqrestore(&current->sighand->siglock, flags);
216
217         dprintk("lockd: clnt proc returns %d\n", status);
218         return status;
219 }
220 EXPORT_SYMBOL(nlmclnt_proc);
221
222 /*
223  * Allocate an NLM RPC call struct
224  *
225  * Note: the caller must hold a reference to host. In case of failure,
226  * this reference will be released.
227  */
228 struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
229 {
230         struct nlm_rqst *call;
231
232         for(;;) {
233                 call = kzalloc(sizeof(*call), GFP_KERNEL);
234                 if (call != NULL) {
235                         locks_init_lock(&call->a_args.lock.fl);
236                         locks_init_lock(&call->a_res.lock.fl);
237                         call->a_host = host;
238                         return call;
239                 }
240                 if (signalled())
241                         break;
242                 printk("nlm_alloc_call: failed, waiting for memory\n");
243                 schedule_timeout_interruptible(5*HZ);
244         }
245         nlm_release_host(host);
246         return NULL;
247 }
248
249 void nlm_release_call(struct nlm_rqst *call)
250 {
251         nlm_release_host(call->a_host);
252         nlmclnt_release_lockargs(call);
253         kfree(call);
254 }
255
256 static void nlmclnt_rpc_release(void *data)
257 {
258         return nlm_release_call(data);
259 }
260
261 static int nlm_wait_on_grace(wait_queue_head_t *queue)
262 {
263         DEFINE_WAIT(wait);
264         int status = -EINTR;
265
266         prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
267         if (!signalled ()) {
268                 schedule_timeout(NLMCLNT_GRACE_WAIT);
269                 try_to_freeze();
270                 if (!signalled ())
271                         status = 0;
272         }
273         finish_wait(queue, &wait);
274         return status;
275 }
276
277 /*
278  * Generic NLM call
279  */
280 static int
281 nlmclnt_call(struct nlm_rqst *req, u32 proc)
282 {
283         struct nlm_host *host = req->a_host;
284         struct rpc_clnt *clnt;
285         struct nlm_args *argp = &req->a_args;
286         struct nlm_res  *resp = &req->a_res;
287         struct rpc_message msg = {
288                 .rpc_argp       = argp,
289                 .rpc_resp       = resp,
290         };
291         int             status;
292
293         dprintk("lockd: call procedure %d on %s\n",
294                         (int)proc, host->h_name);
295
296         do {
297                 if (host->h_reclaiming && !argp->reclaim)
298                         goto in_grace_period;
299
300                 /* If we have no RPC client yet, create one. */
301                 if ((clnt = nlm_bind_host(host)) == NULL)
302                         return -ENOLCK;
303                 msg.rpc_proc = &clnt->cl_procinfo[proc];
304
305                 /* Perform the RPC call. If an error occurs, try again */
306                 if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
307                         dprintk("lockd: rpc_call returned error %d\n", -status);
308                         switch (status) {
309                         case -EPROTONOSUPPORT:
310                                 status = -EINVAL;
311                                 break;
312                         case -ECONNREFUSED:
313                         case -ETIMEDOUT:
314                         case -ENOTCONN:
315                                 nlm_rebind_host(host);
316                                 status = -EAGAIN;
317                                 break;
318                         case -ERESTARTSYS:
319                                 return signalled () ? -EINTR : status;
320                         default:
321                                 break;
322                         }
323                         break;
324                 } else
325                 if (resp->status == NLM_LCK_DENIED_GRACE_PERIOD) {
326                         dprintk("lockd: server in grace period\n");
327                         if (argp->reclaim) {
328                                 printk(KERN_WARNING
329                                      "lockd: spurious grace period reject?!\n");
330                                 return -ENOLCK;
331                         }
332                 } else {
333                         if (!argp->reclaim) {
334                                 /* We appear to be out of the grace period */
335                                 wake_up_all(&host->h_gracewait);
336                         }
337                         dprintk("lockd: server returns status %d\n", resp->status);
338                         return 0;       /* Okay, call complete */
339                 }
340
341 in_grace_period:
342                 /*
343                  * The server has rebooted and appears to be in the grace
344                  * period during which locks are only allowed to be
345                  * reclaimed.
346                  * We can only back off and try again later.
347                  */
348                 status = nlm_wait_on_grace(&host->h_gracewait);
349         } while (status == 0);
350
351         return status;
352 }
353
354 /*
355  * Generic NLM call, async version.
356  */
357 static int __nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
358 {
359         struct nlm_host *host = req->a_host;
360         struct rpc_clnt *clnt;
361         int status = -ENOLCK;
362
363         dprintk("lockd: call procedure %d on %s (async)\n",
364                         (int)proc, host->h_name);
365
366         /* If we have no RPC client yet, create one. */
367         clnt = nlm_bind_host(host);
368         if (clnt == NULL)
369                 goto out_err;
370         msg->rpc_proc = &clnt->cl_procinfo[proc];
371
372         /* bootstrap and kick off the async RPC call */
373         status = rpc_call_async(clnt, msg, RPC_TASK_ASYNC, tk_ops, req);
374         if (status == 0)
375                 return 0;
376 out_err:
377         nlm_release_call(req);
378         return status;
379 }
380
381 int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
382 {
383         struct rpc_message msg = {
384                 .rpc_argp       = &req->a_args,
385                 .rpc_resp       = &req->a_res,
386         };
387         return __nlm_async_call(req, proc, &msg, tk_ops);
388 }
389
390 int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
391 {
392         struct rpc_message msg = {
393                 .rpc_argp       = &req->a_res,
394         };
395         return __nlm_async_call(req, proc, &msg, tk_ops);
396 }
397
398 /*
399  * TEST for the presence of a conflicting lock
400  */
401 static int
402 nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
403 {
404         int     status;
405
406         status = nlmclnt_call(req, NLMPROC_TEST);
407         if (status < 0)
408                 goto out;
409
410         switch (req->a_res.status) {
411                 case NLM_LCK_GRANTED:
412                         fl->fl_type = F_UNLCK;
413                         break;
414                 case NLM_LCK_DENIED:
415                         /*
416                          * Report the conflicting lock back to the application.
417                          */
418                         fl->fl_start = req->a_res.lock.fl.fl_start;
419                         fl->fl_end = req->a_res.lock.fl.fl_start;
420                         fl->fl_type = req->a_res.lock.fl.fl_type;
421                         fl->fl_pid = 0;
422                         break;
423                 default:
424                         status = nlm_stat_to_errno(req->a_res.status);
425         }
426 out:
427         nlm_release_call(req);
428         return status;
429 }
430
431 static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
432 {
433         new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
434         new->fl_u.nfs_fl.owner = nlm_get_lockowner(fl->fl_u.nfs_fl.owner);
435         list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
436 }
437
438 static void nlmclnt_locks_release_private(struct file_lock *fl)
439 {
440         list_del(&fl->fl_u.nfs_fl.list);
441         nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
442 }
443
444 static struct file_lock_operations nlmclnt_lock_ops = {
445         .fl_copy_lock = nlmclnt_locks_copy_lock,
446         .fl_release_private = nlmclnt_locks_release_private,
447 };
448
449 static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
450 {
451         BUG_ON(fl->fl_ops != NULL);
452         fl->fl_u.nfs_fl.state = 0;
453         fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
454         INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
455         fl->fl_ops = &nlmclnt_lock_ops;
456 }
457
458 static void do_vfs_lock(struct file_lock *fl)
459 {
460         int res = 0;
461         switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
462                 case FL_POSIX:
463                         res = posix_lock_file_wait(fl->fl_file, fl);
464                         break;
465                 case FL_FLOCK:
466                         res = flock_lock_file_wait(fl->fl_file, fl);
467                         break;
468                 default:
469                         BUG();
470         }
471         if (res < 0)
472                 printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n",
473                                 __FUNCTION__);
474 }
475
476 /*
477  * LOCK: Try to create a lock
478  *
479  *                      Programmer Harassment Alert
480  *
481  * When given a blocking lock request in a sync RPC call, the HPUX lockd
482  * will faithfully return LCK_BLOCKED but never cares to notify us when
483  * the lock could be granted. This way, our local process could hang
484  * around forever waiting for the callback.
485  *
486  *  Solution A: Implement busy-waiting
487  *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
488  *
489  * For now I am implementing solution A, because I hate the idea of
490  * re-implementing lockd for a third time in two months. The async
491  * calls shouldn't be too hard to do, however.
492  *
493  * This is one of the lovely things about standards in the NFS area:
494  * they're so soft and squishy you can't really blame HP for doing this.
495  */
496 static int
497 nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
498 {
499         struct nlm_host *host = req->a_host;
500         struct nlm_res  *resp = &req->a_res;
501         struct nlm_wait *block = NULL;
502         int status = -ENOLCK;
503
504         if (!host->h_monitored && nsm_monitor(host) < 0) {
505                 printk(KERN_NOTICE "lockd: failed to monitor %s\n",
506                                         host->h_name);
507                 goto out;
508         }
509
510         block = nlmclnt_prepare_block(host, fl);
511 again:
512         for(;;) {
513                 /* Reboot protection */
514                 fl->fl_u.nfs_fl.state = host->h_state;
515                 status = nlmclnt_call(req, NLMPROC_LOCK);
516                 if (status < 0)
517                         goto out_unblock;
518                 if (!req->a_args.block)
519                         break;
520                 /* Did a reclaimer thread notify us of a server reboot? */
521                 if (resp->status ==  NLM_LCK_DENIED_GRACE_PERIOD)
522                         continue;
523                 if (resp->status != NLM_LCK_BLOCKED)
524                         break;
525                 /* Wait on an NLM blocking lock */
526                 status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
527                 /* if we were interrupted. Send a CANCEL request to the server
528                  * and exit
529                  */
530                 if (status < 0)
531                         goto out_unblock;
532                 if (resp->status != NLM_LCK_BLOCKED)
533                         break;
534         }
535
536         if (resp->status == NLM_LCK_GRANTED) {
537                 down_read(&host->h_rwsem);
538                 /* Check whether or not the server has rebooted */
539                 if (fl->fl_u.nfs_fl.state != host->h_state) {
540                         up_read(&host->h_rwsem);
541                         goto again;
542                 }
543                 fl->fl_flags |= FL_SLEEP;
544                 /* Ensure the resulting lock will get added to granted list */
545                 do_vfs_lock(fl);
546                 up_read(&host->h_rwsem);
547         }
548         status = nlm_stat_to_errno(resp->status);
549 out_unblock:
550         nlmclnt_finish_block(block);
551         /* Cancel the blocked request if it is still pending */
552         if (resp->status == NLM_LCK_BLOCKED)
553                 nlmclnt_cancel(host, req->a_args.block, fl);
554 out:
555         nlm_release_call(req);
556         return status;
557 }
558
559 /*
560  * RECLAIM: Try to reclaim a lock
561  */
562 int
563 nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl)
564 {
565         struct nlm_rqst reqst, *req;
566         int             status;
567
568         req = &reqst;
569         memset(req, 0, sizeof(*req));
570         locks_init_lock(&req->a_args.lock.fl);
571         locks_init_lock(&req->a_res.lock.fl);
572         req->a_host  = host;
573         req->a_flags = 0;
574
575         /* Set up the argument struct */
576         nlmclnt_setlockargs(req, fl);
577         req->a_args.reclaim = 1;
578
579         if ((status = nlmclnt_call(req, NLMPROC_LOCK)) >= 0
580          && req->a_res.status == NLM_LCK_GRANTED)
581                 return 0;
582
583         printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
584                                 "(errno %d, status %d)\n", fl->fl_pid,
585                                 status, req->a_res.status);
586
587         /*
588          * FIXME: This is a serious failure. We can
589          *
590          *  a.  Ignore the problem
591          *  b.  Send the owning process some signal (Linux doesn't have
592          *      SIGLOST, though...)
593          *  c.  Retry the operation
594          *
595          * Until someone comes up with a simple implementation
596          * for b or c, I'll choose option a.
597          */
598
599         return -ENOLCK;
600 }
601
602 /*
603  * UNLOCK: remove an existing lock
604  */
605 static int
606 nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
607 {
608         struct nlm_host *host = req->a_host;
609         struct nlm_res  *resp = &req->a_res;
610         int             status;
611
612         /*
613          * Note: the server is supposed to either grant us the unlock
614          * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
615          * case, we want to unlock.
616          */
617         down_read(&host->h_rwsem);
618         do_vfs_lock(fl);
619         up_read(&host->h_rwsem);
620
621         if (req->a_flags & RPC_TASK_ASYNC)
622                 return nlm_async_call(req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
623
624         status = nlmclnt_call(req, NLMPROC_UNLOCK);
625         if (status < 0)
626                 goto out;
627
628         status = 0;
629         if (resp->status == NLM_LCK_GRANTED)
630                 goto out;
631
632         if (resp->status != NLM_LCK_DENIED_NOLOCKS)
633                 printk("lockd: unexpected unlock status: %d\n", resp->status);
634         /* What to do now? I'm out of my depth... */
635         status = -ENOLCK;
636 out:
637         nlm_release_call(req);
638         return status;
639 }
640
641 static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
642 {
643         struct nlm_rqst *req = data;
644         int             status = req->a_res.status;
645
646         if (RPC_ASSASSINATED(task))
647                 goto die;
648
649         if (task->tk_status < 0) {
650                 dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
651                 goto retry_rebind;
652         }
653         if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
654                 rpc_delay(task, NLMCLNT_GRACE_WAIT);
655                 goto retry_unlock;
656         }
657         if (status != NLM_LCK_GRANTED)
658                 printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
659 die:
660         return;
661  retry_rebind:
662         nlm_rebind_host(req->a_host);
663  retry_unlock:
664         rpc_restart_call(task);
665 }
666
667 static const struct rpc_call_ops nlmclnt_unlock_ops = {
668         .rpc_call_done = nlmclnt_unlock_callback,
669         .rpc_release = nlmclnt_rpc_release,
670 };
671
672 /*
673  * Cancel a blocked lock request.
674  * We always use an async RPC call for this in order not to hang a
675  * process that has been Ctrl-C'ed.
676  */
677 static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
678 {
679         struct nlm_rqst *req;
680         unsigned long   flags;
681         sigset_t        oldset;
682         int             status;
683
684         /* Block all signals while setting up call */
685         spin_lock_irqsave(&current->sighand->siglock, flags);
686         oldset = current->blocked;
687         sigfillset(&current->blocked);
688         recalc_sigpending();
689         spin_unlock_irqrestore(&current->sighand->siglock, flags);
690
691         req = nlm_alloc_call(nlm_get_host(host));
692         if (!req)
693                 return -ENOMEM;
694         req->a_flags = RPC_TASK_ASYNC;
695
696         nlmclnt_setlockargs(req, fl);
697         req->a_args.block = block;
698
699         status = nlm_async_call(req, NLMPROC_CANCEL, &nlmclnt_cancel_ops);
700
701         spin_lock_irqsave(&current->sighand->siglock, flags);
702         current->blocked = oldset;
703         recalc_sigpending();
704         spin_unlock_irqrestore(&current->sighand->siglock, flags);
705
706         return status;
707 }
708
709 static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
710 {
711         struct nlm_rqst *req = data;
712
713         if (RPC_ASSASSINATED(task))
714                 goto die;
715
716         if (task->tk_status < 0) {
717                 dprintk("lockd: CANCEL call error %d, retrying.\n",
718                                         task->tk_status);
719                 goto retry_cancel;
720         }
721
722         dprintk("lockd: cancel status %d (task %d)\n",
723                         req->a_res.status, task->tk_pid);
724
725         switch (req->a_res.status) {
726         case NLM_LCK_GRANTED:
727         case NLM_LCK_DENIED_GRACE_PERIOD:
728         case NLM_LCK_DENIED:
729                 /* Everything's good */
730                 break;
731         case NLM_LCK_DENIED_NOLOCKS:
732                 dprintk("lockd: CANCEL failed (server has no locks)\n");
733                 goto retry_cancel;
734         default:
735                 printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
736                         req->a_res.status);
737         }
738
739 die:
740         return;
741
742 retry_cancel:
743         /* Don't ever retry more than 3 times */
744         if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
745                 goto die;
746         nlm_rebind_host(req->a_host);
747         rpc_restart_call(task);
748         rpc_delay(task, 30 * HZ);
749 }
750
751 static const struct rpc_call_ops nlmclnt_cancel_ops = {
752         .rpc_call_done = nlmclnt_cancel_callback,
753         .rpc_release = nlmclnt_rpc_release,
754 };
755
756 /*
757  * Convert an NLM status code to a generic kernel errno
758  */
759 static int
760 nlm_stat_to_errno(u32 status)
761 {
762         switch(status) {
763         case NLM_LCK_GRANTED:
764                 return 0;
765         case NLM_LCK_DENIED:
766                 return -EAGAIN;
767         case NLM_LCK_DENIED_NOLOCKS:
768         case NLM_LCK_DENIED_GRACE_PERIOD:
769                 return -ENOLCK;
770         case NLM_LCK_BLOCKED:
771                 printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
772                 return -ENOLCK;
773 #ifdef CONFIG_LOCKD_V4
774         case NLM_DEADLCK:
775                 return -EDEADLK;
776         case NLM_ROFS:
777                 return -EROFS;
778         case NLM_STALE_FH:
779                 return -ESTALE;
780         case NLM_FBIG:
781                 return -EOVERFLOW;
782         case NLM_FAILED:
783                 return -ENOLCK;
784 #endif
785         }
786         printk(KERN_NOTICE "lockd: unexpected server status %d\n", status);
787         return -ENOLCK;
788 }