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Linux/fs/lockd/clntproc.c

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

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