close the race in nlmsvc_free_block()
[linux-3.10.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/module.h>
10 #include <linux/slab.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/freezer.h>
17 #include <linux/sunrpc/clnt.h>
18 #include <linux/sunrpc/svc.h>
19 #include <linux/lockd/lockd.h>
20
21 #define NLMDBG_FACILITY         NLMDBG_CLIENT
22 #define NLMCLNT_GRACE_WAIT      (5*HZ)
23 #define NLMCLNT_POLL_TIMEOUT    (30*HZ)
24 #define NLMCLNT_MAX_RETRIES     3
25
26 static int      nlmclnt_test(struct nlm_rqst *, struct file_lock *);
27 static int      nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
28 static int      nlmclnt_unlock(struct nlm_rqst *, struct file_lock *);
29 static int      nlm_stat_to_errno(__be32 stat);
30 static void     nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host);
31 static int      nlmclnt_cancel(struct nlm_host *, int , struct file_lock *);
32
33 static const struct rpc_call_ops nlmclnt_unlock_ops;
34 static const struct rpc_call_ops nlmclnt_cancel_ops;
35
36 /*
37  * Cookie counter for NLM requests
38  */
39 static atomic_t nlm_cookie = ATOMIC_INIT(0x1234);
40
41 void nlmclnt_next_cookie(struct nlm_cookie *c)
42 {
43         u32     cookie = atomic_inc_return(&nlm_cookie);
44
45         memcpy(c->data, &cookie, 4);
46         c->len=4;
47 }
48
49 static struct nlm_lockowner *nlm_get_lockowner(struct nlm_lockowner *lockowner)
50 {
51         atomic_inc(&lockowner->count);
52         return lockowner;
53 }
54
55 static void nlm_put_lockowner(struct nlm_lockowner *lockowner)
56 {
57         if (!atomic_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
58                 return;
59         list_del(&lockowner->list);
60         spin_unlock(&lockowner->host->h_lock);
61         nlmclnt_release_host(lockowner->host);
62         kfree(lockowner);
63 }
64
65 static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
66 {
67         struct nlm_lockowner *lockowner;
68         list_for_each_entry(lockowner, &host->h_lockowners, list) {
69                 if (lockowner->pid == pid)
70                         return -EBUSY;
71         }
72         return 0;
73 }
74
75 static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
76 {
77         uint32_t res;
78         do {
79                 res = host->h_pidcount++;
80         } while (nlm_pidbusy(host, res) < 0);
81         return res;
82 }
83
84 static struct nlm_lockowner *__nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
85 {
86         struct nlm_lockowner *lockowner;
87         list_for_each_entry(lockowner, &host->h_lockowners, list) {
88                 if (lockowner->owner != owner)
89                         continue;
90                 return nlm_get_lockowner(lockowner);
91         }
92         return NULL;
93 }
94
95 static struct nlm_lockowner *nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
96 {
97         struct nlm_lockowner *res, *new = NULL;
98
99         spin_lock(&host->h_lock);
100         res = __nlm_find_lockowner(host, owner);
101         if (res == NULL) {
102                 spin_unlock(&host->h_lock);
103                 new = kmalloc(sizeof(*new), GFP_KERNEL);
104                 spin_lock(&host->h_lock);
105                 res = __nlm_find_lockowner(host, owner);
106                 if (res == NULL && new != NULL) {
107                         res = new;
108                         atomic_set(&new->count, 1);
109                         new->owner = owner;
110                         new->pid = __nlm_alloc_pid(host);
111                         new->host = nlm_get_host(host);
112                         list_add(&new->list, &host->h_lockowners);
113                         new = NULL;
114                 }
115         }
116         spin_unlock(&host->h_lock);
117         kfree(new);
118         return res;
119 }
120
121 /*
122  * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
123  */
124 static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
125 {
126         struct nlm_args *argp = &req->a_args;
127         struct nlm_lock *lock = &argp->lock;
128
129         nlmclnt_next_cookie(&argp->cookie);
130         memcpy(&lock->fh, NFS_FH(fl->fl_file->f_path.dentry->d_inode), sizeof(struct nfs_fh));
131         lock->caller  = utsname()->nodename;
132         lock->oh.data = req->a_owner;
133         lock->oh.len  = snprintf(req->a_owner, sizeof(req->a_owner), "%u@%s",
134                                 (unsigned int)fl->fl_u.nfs_fl.owner->pid,
135                                 utsname()->nodename);
136         lock->svid = fl->fl_u.nfs_fl.owner->pid;
137         lock->fl.fl_start = fl->fl_start;
138         lock->fl.fl_end = fl->fl_end;
139         lock->fl.fl_type = fl->fl_type;
140 }
141
142 static void nlmclnt_release_lockargs(struct nlm_rqst *req)
143 {
144         BUG_ON(req->a_args.lock.fl.fl_ops != NULL);
145 }
146
147 /**
148  * nlmclnt_proc - Perform a single client-side lock request
149  * @host: address of a valid nlm_host context representing the NLM server
150  * @cmd: fcntl-style file lock operation to perform
151  * @fl: address of arguments for the lock operation
152  *
153  */
154 int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl)
155 {
156         struct nlm_rqst         *call;
157         int                     status;
158
159         call = nlm_alloc_call(host);
160         if (call == NULL)
161                 return -ENOMEM;
162
163         nlmclnt_locks_init_private(fl, host);
164         if (!fl->fl_u.nfs_fl.owner) {
165                 /* lockowner allocation has failed */
166                 nlmclnt_release_call(call);
167                 return -ENOMEM;
168         }
169         /* Set up the argument struct */
170         nlmclnt_setlockargs(call, fl);
171
172         if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
173                 if (fl->fl_type != F_UNLCK) {
174                         call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
175                         status = nlmclnt_lock(call, fl);
176                 } else
177                         status = nlmclnt_unlock(call, fl);
178         } else if (IS_GETLK(cmd))
179                 status = nlmclnt_test(call, fl);
180         else
181                 status = -EINVAL;
182         fl->fl_ops->fl_release_private(fl);
183         fl->fl_ops = NULL;
184
185         dprintk("lockd: clnt proc returns %d\n", status);
186         return status;
187 }
188 EXPORT_SYMBOL_GPL(nlmclnt_proc);
189
190 /*
191  * Allocate an NLM RPC call struct
192  */
193 struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
194 {
195         struct nlm_rqst *call;
196
197         for(;;) {
198                 call = kzalloc(sizeof(*call), GFP_KERNEL);
199                 if (call != NULL) {
200                         atomic_set(&call->a_count, 1);
201                         locks_init_lock(&call->a_args.lock.fl);
202                         locks_init_lock(&call->a_res.lock.fl);
203                         call->a_host = nlm_get_host(host);
204                         return call;
205                 }
206                 if (signalled())
207                         break;
208                 printk("nlm_alloc_call: failed, waiting for memory\n");
209                 schedule_timeout_interruptible(5*HZ);
210         }
211         return NULL;
212 }
213
214 void nlmclnt_release_call(struct nlm_rqst *call)
215 {
216         if (!atomic_dec_and_test(&call->a_count))
217                 return;
218         nlmclnt_release_host(call->a_host);
219         nlmclnt_release_lockargs(call);
220         kfree(call);
221 }
222
223 static void nlmclnt_rpc_release(void *data)
224 {
225         nlmclnt_release_call(data);
226 }
227
228 static int nlm_wait_on_grace(wait_queue_head_t *queue)
229 {
230         DEFINE_WAIT(wait);
231         int status = -EINTR;
232
233         prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
234         if (!signalled ()) {
235                 schedule_timeout(NLMCLNT_GRACE_WAIT);
236                 try_to_freeze();
237                 if (!signalled ())
238                         status = 0;
239         }
240         finish_wait(queue, &wait);
241         return status;
242 }
243
244 /*
245  * Generic NLM call
246  */
247 static int
248 nlmclnt_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc)
249 {
250         struct nlm_host *host = req->a_host;
251         struct rpc_clnt *clnt;
252         struct nlm_args *argp = &req->a_args;
253         struct nlm_res  *resp = &req->a_res;
254         struct rpc_message msg = {
255                 .rpc_argp       = argp,
256                 .rpc_resp       = resp,
257                 .rpc_cred       = cred,
258         };
259         int             status;
260
261         dprintk("lockd: call procedure %d on %s\n",
262                         (int)proc, host->h_name);
263
264         do {
265                 if (host->h_reclaiming && !argp->reclaim)
266                         goto in_grace_period;
267
268                 /* If we have no RPC client yet, create one. */
269                 if ((clnt = nlm_bind_host(host)) == NULL)
270                         return -ENOLCK;
271                 msg.rpc_proc = &clnt->cl_procinfo[proc];
272
273                 /* Perform the RPC call. If an error occurs, try again */
274                 if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
275                         dprintk("lockd: rpc_call returned error %d\n", -status);
276                         switch (status) {
277                         case -EPROTONOSUPPORT:
278                                 status = -EINVAL;
279                                 break;
280                         case -ECONNREFUSED:
281                         case -ETIMEDOUT:
282                         case -ENOTCONN:
283                                 nlm_rebind_host(host);
284                                 status = -EAGAIN;
285                                 break;
286                         case -ERESTARTSYS:
287                                 return signalled () ? -EINTR : status;
288                         default:
289                                 break;
290                         }
291                         break;
292                 } else
293                 if (resp->status == nlm_lck_denied_grace_period) {
294                         dprintk("lockd: server in grace period\n");
295                         if (argp->reclaim) {
296                                 printk(KERN_WARNING
297                                      "lockd: spurious grace period reject?!\n");
298                                 return -ENOLCK;
299                         }
300                 } else {
301                         if (!argp->reclaim) {
302                                 /* We appear to be out of the grace period */
303                                 wake_up_all(&host->h_gracewait);
304                         }
305                         dprintk("lockd: server returns status %d\n",
306                                 ntohl(resp->status));
307                         return 0;       /* Okay, call complete */
308                 }
309
310 in_grace_period:
311                 /*
312                  * The server has rebooted and appears to be in the grace
313                  * period during which locks are only allowed to be
314                  * reclaimed.
315                  * We can only back off and try again later.
316                  */
317                 status = nlm_wait_on_grace(&host->h_gracewait);
318         } while (status == 0);
319
320         return status;
321 }
322
323 /*
324  * Generic NLM call, async version.
325  */
326 static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
327 {
328         struct nlm_host *host = req->a_host;
329         struct rpc_clnt *clnt;
330         struct rpc_task_setup task_setup_data = {
331                 .rpc_message = msg,
332                 .callback_ops = tk_ops,
333                 .callback_data = req,
334                 .flags = RPC_TASK_ASYNC,
335         };
336
337         dprintk("lockd: call procedure %d on %s (async)\n",
338                         (int)proc, host->h_name);
339
340         /* If we have no RPC client yet, create one. */
341         clnt = nlm_bind_host(host);
342         if (clnt == NULL)
343                 goto out_err;
344         msg->rpc_proc = &clnt->cl_procinfo[proc];
345         task_setup_data.rpc_client = clnt;
346
347         /* bootstrap and kick off the async RPC call */
348         return rpc_run_task(&task_setup_data);
349 out_err:
350         tk_ops->rpc_release(req);
351         return ERR_PTR(-ENOLCK);
352 }
353
354 static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
355 {
356         struct rpc_task *task;
357
358         task = __nlm_async_call(req, proc, msg, tk_ops);
359         if (IS_ERR(task))
360                 return PTR_ERR(task);
361         rpc_put_task(task);
362         return 0;
363 }
364
365 /*
366  * NLM asynchronous call.
367  */
368 int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
369 {
370         struct rpc_message msg = {
371                 .rpc_argp       = &req->a_args,
372                 .rpc_resp       = &req->a_res,
373         };
374         return nlm_do_async_call(req, proc, &msg, tk_ops);
375 }
376
377 int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
378 {
379         struct rpc_message msg = {
380                 .rpc_argp       = &req->a_res,
381         };
382         return nlm_do_async_call(req, proc, &msg, tk_ops);
383 }
384
385 /*
386  * NLM client asynchronous call.
387  *
388  * Note that although the calls are asynchronous, and are therefore
389  *      guaranteed to complete, we still always attempt to wait for
390  *      completion in order to be able to correctly track the lock
391  *      state.
392  */
393 static int nlmclnt_async_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
394 {
395         struct rpc_message msg = {
396                 .rpc_argp       = &req->a_args,
397                 .rpc_resp       = &req->a_res,
398                 .rpc_cred       = cred,
399         };
400         struct rpc_task *task;
401         int err;
402
403         task = __nlm_async_call(req, proc, &msg, tk_ops);
404         if (IS_ERR(task))
405                 return PTR_ERR(task);
406         err = rpc_wait_for_completion_task(task);
407         rpc_put_task(task);
408         return err;
409 }
410
411 /*
412  * TEST for the presence of a conflicting lock
413  */
414 static int
415 nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
416 {
417         int     status;
418
419         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
420         if (status < 0)
421                 goto out;
422
423         switch (req->a_res.status) {
424                 case nlm_granted:
425                         fl->fl_type = F_UNLCK;
426                         break;
427                 case nlm_lck_denied:
428                         /*
429                          * Report the conflicting lock back to the application.
430                          */
431                         fl->fl_start = req->a_res.lock.fl.fl_start;
432                         fl->fl_end = req->a_res.lock.fl.fl_end;
433                         fl->fl_type = req->a_res.lock.fl.fl_type;
434                         fl->fl_pid = 0;
435                         break;
436                 default:
437                         status = nlm_stat_to_errno(req->a_res.status);
438         }
439 out:
440         nlmclnt_release_call(req);
441         return status;
442 }
443
444 static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
445 {
446         spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
447         new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
448         new->fl_u.nfs_fl.owner = nlm_get_lockowner(fl->fl_u.nfs_fl.owner);
449         list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
450         spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
451 }
452
453 static void nlmclnt_locks_release_private(struct file_lock *fl)
454 {
455         spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
456         list_del(&fl->fl_u.nfs_fl.list);
457         spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
458         nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
459 }
460
461 static const struct file_lock_operations nlmclnt_lock_ops = {
462         .fl_copy_lock = nlmclnt_locks_copy_lock,
463         .fl_release_private = nlmclnt_locks_release_private,
464 };
465
466 static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
467 {
468         BUG_ON(fl->fl_ops != NULL);
469         fl->fl_u.nfs_fl.state = 0;
470         fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
471         INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
472         fl->fl_ops = &nlmclnt_lock_ops;
473 }
474
475 static int do_vfs_lock(struct file_lock *fl)
476 {
477         int res = 0;
478         switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
479                 case FL_POSIX:
480                         res = posix_lock_file_wait(fl->fl_file, fl);
481                         break;
482                 case FL_FLOCK:
483                         res = flock_lock_file_wait(fl->fl_file, fl);
484                         break;
485                 default:
486                         BUG();
487         }
488         return res;
489 }
490
491 /*
492  * LOCK: Try to create a lock
493  *
494  *                      Programmer Harassment Alert
495  *
496  * When given a blocking lock request in a sync RPC call, the HPUX lockd
497  * will faithfully return LCK_BLOCKED but never cares to notify us when
498  * the lock could be granted. This way, our local process could hang
499  * around forever waiting for the callback.
500  *
501  *  Solution A: Implement busy-waiting
502  *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
503  *
504  * For now I am implementing solution A, because I hate the idea of
505  * re-implementing lockd for a third time in two months. The async
506  * calls shouldn't be too hard to do, however.
507  *
508  * This is one of the lovely things about standards in the NFS area:
509  * they're so soft and squishy you can't really blame HP for doing this.
510  */
511 static int
512 nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
513 {
514         struct rpc_cred *cred = nfs_file_cred(fl->fl_file);
515         struct nlm_host *host = req->a_host;
516         struct nlm_res  *resp = &req->a_res;
517         struct nlm_wait *block = NULL;
518         unsigned char fl_flags = fl->fl_flags;
519         unsigned char fl_type;
520         int status = -ENOLCK;
521
522         if (nsm_monitor(host) < 0)
523                 goto out;
524         req->a_args.state = nsm_local_state;
525
526         fl->fl_flags |= FL_ACCESS;
527         status = do_vfs_lock(fl);
528         fl->fl_flags = fl_flags;
529         if (status < 0)
530                 goto out;
531
532         block = nlmclnt_prepare_block(host, fl);
533 again:
534         /*
535          * Initialise resp->status to a valid non-zero value,
536          * since 0 == nlm_lck_granted
537          */
538         resp->status = nlm_lck_blocked;
539         for(;;) {
540                 /* Reboot protection */
541                 fl->fl_u.nfs_fl.state = host->h_state;
542                 status = nlmclnt_call(cred, req, NLMPROC_LOCK);
543                 if (status < 0)
544                         break;
545                 /* Did a reclaimer thread notify us of a server reboot? */
546                 if (resp->status ==  nlm_lck_denied_grace_period)
547                         continue;
548                 if (resp->status != nlm_lck_blocked)
549                         break;
550                 /* Wait on an NLM blocking lock */
551                 status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
552                 if (status < 0)
553                         break;
554                 if (resp->status != nlm_lck_blocked)
555                         break;
556         }
557
558         /* if we were interrupted while blocking, then cancel the lock request
559          * and exit
560          */
561         if (resp->status == nlm_lck_blocked) {
562                 if (!req->a_args.block)
563                         goto out_unlock;
564                 if (nlmclnt_cancel(host, req->a_args.block, fl) == 0)
565                         goto out_unblock;
566         }
567
568         if (resp->status == nlm_granted) {
569                 down_read(&host->h_rwsem);
570                 /* Check whether or not the server has rebooted */
571                 if (fl->fl_u.nfs_fl.state != host->h_state) {
572                         up_read(&host->h_rwsem);
573                         goto again;
574                 }
575                 /* Ensure the resulting lock will get added to granted list */
576                 fl->fl_flags |= FL_SLEEP;
577                 if (do_vfs_lock(fl) < 0)
578                         printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
579                 up_read(&host->h_rwsem);
580                 fl->fl_flags = fl_flags;
581                 status = 0;
582         }
583         if (status < 0)
584                 goto out_unlock;
585         /*
586          * EAGAIN doesn't make sense for sleeping locks, and in some
587          * cases NLM_LCK_DENIED is returned for a permanent error.  So
588          * turn it into an ENOLCK.
589          */
590         if (resp->status == nlm_lck_denied && (fl_flags & FL_SLEEP))
591                 status = -ENOLCK;
592         else
593                 status = nlm_stat_to_errno(resp->status);
594 out_unblock:
595         nlmclnt_finish_block(block);
596 out:
597         nlmclnt_release_call(req);
598         return status;
599 out_unlock:
600         /* Fatal error: ensure that we remove the lock altogether */
601         dprintk("lockd: lock attempt ended in fatal error.\n"
602                 "       Attempting to unlock.\n");
603         nlmclnt_finish_block(block);
604         fl_type = fl->fl_type;
605         fl->fl_type = F_UNLCK;
606         down_read(&host->h_rwsem);
607         do_vfs_lock(fl);
608         up_read(&host->h_rwsem);
609         fl->fl_type = fl_type;
610         fl->fl_flags = fl_flags;
611         nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
612         return status;
613 }
614
615 /*
616  * RECLAIM: Try to reclaim a lock
617  */
618 int
619 nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl)
620 {
621         struct nlm_rqst reqst, *req;
622         int             status;
623
624         req = &reqst;
625         memset(req, 0, sizeof(*req));
626         locks_init_lock(&req->a_args.lock.fl);
627         locks_init_lock(&req->a_res.lock.fl);
628         req->a_host  = host;
629         req->a_flags = 0;
630
631         /* Set up the argument struct */
632         nlmclnt_setlockargs(req, fl);
633         req->a_args.reclaim = 1;
634
635         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK);
636         if (status >= 0 && req->a_res.status == nlm_granted)
637                 return 0;
638
639         printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
640                                 "(errno %d, status %d)\n", fl->fl_pid,
641                                 status, ntohl(req->a_res.status));
642
643         /*
644          * FIXME: This is a serious failure. We can
645          *
646          *  a.  Ignore the problem
647          *  b.  Send the owning process some signal (Linux doesn't have
648          *      SIGLOST, though...)
649          *  c.  Retry the operation
650          *
651          * Until someone comes up with a simple implementation
652          * for b or c, I'll choose option a.
653          */
654
655         return -ENOLCK;
656 }
657
658 /*
659  * UNLOCK: remove an existing lock
660  */
661 static int
662 nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
663 {
664         struct nlm_host *host = req->a_host;
665         struct nlm_res  *resp = &req->a_res;
666         int status;
667         unsigned char fl_flags = fl->fl_flags;
668
669         /*
670          * Note: the server is supposed to either grant us the unlock
671          * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
672          * case, we want to unlock.
673          */
674         fl->fl_flags |= FL_EXISTS;
675         down_read(&host->h_rwsem);
676         status = do_vfs_lock(fl);
677         up_read(&host->h_rwsem);
678         fl->fl_flags = fl_flags;
679         if (status == -ENOENT) {
680                 status = 0;
681                 goto out;
682         }
683
684         atomic_inc(&req->a_count);
685         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
686                         NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
687         if (status < 0)
688                 goto out;
689
690         if (resp->status == nlm_granted)
691                 goto out;
692
693         if (resp->status != nlm_lck_denied_nolocks)
694                 printk("lockd: unexpected unlock status: %d\n",
695                         ntohl(resp->status));
696         /* What to do now? I'm out of my depth... */
697         status = -ENOLCK;
698 out:
699         nlmclnt_release_call(req);
700         return status;
701 }
702
703 static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
704 {
705         struct nlm_rqst *req = data;
706         u32 status = ntohl(req->a_res.status);
707
708         if (RPC_ASSASSINATED(task))
709                 goto die;
710
711         if (task->tk_status < 0) {
712                 dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
713                 switch (task->tk_status) {
714                 case -EACCES:
715                 case -EIO:
716                         goto die;
717                 default:
718                         goto retry_rebind;
719                 }
720         }
721         if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
722                 rpc_delay(task, NLMCLNT_GRACE_WAIT);
723                 goto retry_unlock;
724         }
725         if (status != NLM_LCK_GRANTED)
726                 printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
727 die:
728         return;
729  retry_rebind:
730         nlm_rebind_host(req->a_host);
731  retry_unlock:
732         rpc_restart_call(task);
733 }
734
735 static const struct rpc_call_ops nlmclnt_unlock_ops = {
736         .rpc_call_done = nlmclnt_unlock_callback,
737         .rpc_release = nlmclnt_rpc_release,
738 };
739
740 /*
741  * Cancel a blocked lock request.
742  * We always use an async RPC call for this in order not to hang a
743  * process that has been Ctrl-C'ed.
744  */
745 static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
746 {
747         struct nlm_rqst *req;
748         int status;
749
750         dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
751                 "       Attempting to cancel lock.\n");
752
753         req = nlm_alloc_call(host);
754         if (!req)
755                 return -ENOMEM;
756         req->a_flags = RPC_TASK_ASYNC;
757
758         nlmclnt_setlockargs(req, fl);
759         req->a_args.block = block;
760
761         atomic_inc(&req->a_count);
762         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
763                         NLMPROC_CANCEL, &nlmclnt_cancel_ops);
764         if (status == 0 && req->a_res.status == nlm_lck_denied)
765                 status = -ENOLCK;
766         nlmclnt_release_call(req);
767         return status;
768 }
769
770 static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
771 {
772         struct nlm_rqst *req = data;
773         u32 status = ntohl(req->a_res.status);
774
775         if (RPC_ASSASSINATED(task))
776                 goto die;
777
778         if (task->tk_status < 0) {
779                 dprintk("lockd: CANCEL call error %d, retrying.\n",
780                                         task->tk_status);
781                 goto retry_cancel;
782         }
783
784         dprintk("lockd: cancel status %u (task %u)\n",
785                         status, task->tk_pid);
786
787         switch (status) {
788         case NLM_LCK_GRANTED:
789         case NLM_LCK_DENIED_GRACE_PERIOD:
790         case NLM_LCK_DENIED:
791                 /* Everything's good */
792                 break;
793         case NLM_LCK_DENIED_NOLOCKS:
794                 dprintk("lockd: CANCEL failed (server has no locks)\n");
795                 goto retry_cancel;
796         default:
797                 printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
798                         status);
799         }
800
801 die:
802         return;
803
804 retry_cancel:
805         /* Don't ever retry more than 3 times */
806         if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
807                 goto die;
808         nlm_rebind_host(req->a_host);
809         rpc_restart_call(task);
810         rpc_delay(task, 30 * HZ);
811 }
812
813 static const struct rpc_call_ops nlmclnt_cancel_ops = {
814         .rpc_call_done = nlmclnt_cancel_callback,
815         .rpc_release = nlmclnt_rpc_release,
816 };
817
818 /*
819  * Convert an NLM status code to a generic kernel errno
820  */
821 static int
822 nlm_stat_to_errno(__be32 status)
823 {
824         switch(ntohl(status)) {
825         case NLM_LCK_GRANTED:
826                 return 0;
827         case NLM_LCK_DENIED:
828                 return -EAGAIN;
829         case NLM_LCK_DENIED_NOLOCKS:
830         case NLM_LCK_DENIED_GRACE_PERIOD:
831                 return -ENOLCK;
832         case NLM_LCK_BLOCKED:
833                 printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
834                 return -ENOLCK;
835 #ifdef CONFIG_LOCKD_V4
836         case NLM_DEADLCK:
837                 return -EDEADLK;
838         case NLM_ROFS:
839                 return -EROFS;
840         case NLM_STALE_FH:
841                 return -ESTALE;
842         case NLM_FBIG:
843                 return -EOVERFLOW;
844         case NLM_FAILED:
845                 return -ENOLCK;
846 #endif
847         }
848         printk(KERN_NOTICE "lockd: unexpected server status %d\n",
849                  ntohl(status));
850         return -ENOLCK;
851 }