1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * linux/fs/lockd/clntproc.c
4  *
5  * RPC procedures for the client side NLM implementation
6  *
7  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
8  */
9 
10 #include <linux/module.h>
11 #include <linux/slab.h>
12 #include <linux/types.h>
13 #include <linux/errno.h>
14 #include <linux/fs.h>
15 #include <linux/nfs_fs.h>
16 #include <linux/utsname.h>
17 #include <linux/freezer.h>
18 #include <linux/sunrpc/clnt.h>
19 #include <linux/sunrpc/svc.h>
20 #include <linux/lockd/lockd.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(__be32 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 atomic_t	nlm_cookie = ATOMIC_INIT(0x1234);
41 
nlmclnt_next_cookie(struct nlm_cookie * c)42 void nlmclnt_next_cookie(struct nlm_cookie *c)
43 {
44 	u32	cookie = atomic_inc_return(&nlm_cookie);
45 
46 	memcpy(c->data, &cookie, 4);
47 	c->len=4;
48 }
49 
50 static struct nlm_lockowner *
nlmclnt_get_lockowner(struct nlm_lockowner * lockowner)51 nlmclnt_get_lockowner(struct nlm_lockowner *lockowner)
52 {
53 	refcount_inc(&lockowner->count);
54 	return lockowner;
55 }
56 
nlmclnt_put_lockowner(struct nlm_lockowner * lockowner)57 static void nlmclnt_put_lockowner(struct nlm_lockowner *lockowner)
58 {
59 	if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
60 		return;
61 	list_del(&lockowner->list);
62 	spin_unlock(&lockowner->host->h_lock);
63 	nlmclnt_release_host(lockowner->host);
64 	kfree(lockowner);
65 }
66 
nlm_pidbusy(struct nlm_host * host,uint32_t pid)67 static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
68 {
69 	struct nlm_lockowner *lockowner;
70 	list_for_each_entry(lockowner, &host->h_lockowners, list) {
71 		if (lockowner->pid == pid)
72 			return -EBUSY;
73 	}
74 	return 0;
75 }
76 
__nlm_alloc_pid(struct nlm_host * host)77 static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
78 {
79 	uint32_t res;
80 	do {
81 		res = host->h_pidcount++;
82 	} while (nlm_pidbusy(host, res) < 0);
83 	return res;
84 }
85 
__nlmclnt_find_lockowner(struct nlm_host * host,fl_owner_t owner)86 static struct nlm_lockowner *__nlmclnt_find_lockowner(struct nlm_host *host, fl_owner_t owner)
87 {
88 	struct nlm_lockowner *lockowner;
89 	list_for_each_entry(lockowner, &host->h_lockowners, list) {
90 		if (lockowner->owner != owner)
91 			continue;
92 		return nlmclnt_get_lockowner(lockowner);
93 	}
94 	return NULL;
95 }
96 
nlmclnt_find_lockowner(struct nlm_host * host,fl_owner_t owner)97 static struct nlm_lockowner *nlmclnt_find_lockowner(struct nlm_host *host, fl_owner_t owner)
98 {
99 	struct nlm_lockowner *res, *new = NULL;
100 
101 	spin_lock(&host->h_lock);
102 	res = __nlmclnt_find_lockowner(host, owner);
103 	if (res == NULL) {
104 		spin_unlock(&host->h_lock);
105 		new = kmalloc(sizeof(*new), GFP_KERNEL);
106 		spin_lock(&host->h_lock);
107 		res = __nlmclnt_find_lockowner(host, owner);
108 		if (res == NULL && new != NULL) {
109 			res = new;
110 			refcount_set(&new->count, 1);
111 			new->owner = owner;
112 			new->pid = __nlm_alloc_pid(host);
113 			new->host = nlm_get_host(host);
114 			list_add(&new->list, &host->h_lockowners);
115 			new = NULL;
116 		}
117 	}
118 	spin_unlock(&host->h_lock);
119 	kfree(new);
120 	return res;
121 }
122 
123 /*
124  * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
125  */
nlmclnt_setlockargs(struct nlm_rqst * req,struct file_lock * fl)126 static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
127 {
128 	struct nlm_args	*argp = &req->a_args;
129 	struct nlm_lock	*lock = &argp->lock;
130 	char *nodename = req->a_host->h_rpcclnt->cl_nodename;
131 
132 	nlmclnt_next_cookie(&argp->cookie);
133 	memcpy(&lock->fh, NFS_FH(locks_inode(fl->fl_file)), sizeof(struct nfs_fh));
134 	lock->caller  = nodename;
135 	lock->oh.data = req->a_owner;
136 	lock->oh.len  = snprintf(req->a_owner, sizeof(req->a_owner), "%u@%s",
137 				(unsigned int)fl->fl_u.nfs_fl.owner->pid,
138 				nodename);
139 	lock->svid = fl->fl_u.nfs_fl.owner->pid;
140 	lock->fl.fl_start = fl->fl_start;
141 	lock->fl.fl_end = fl->fl_end;
142 	lock->fl.fl_type = fl->fl_type;
143 }
144 
nlmclnt_release_lockargs(struct nlm_rqst * req)145 static void nlmclnt_release_lockargs(struct nlm_rqst *req)
146 {
147 	WARN_ON_ONCE(req->a_args.lock.fl.fl_ops != NULL);
148 }
149 
150 /**
151  * nlmclnt_proc - Perform a single client-side lock request
152  * @host: address of a valid nlm_host context representing the NLM server
153  * @cmd: fcntl-style file lock operation to perform
154  * @fl: address of arguments for the lock operation
155  * @data: address of data to be sent to callback operations
156  *
157  */
nlmclnt_proc(struct nlm_host * host,int cmd,struct file_lock * fl,void * data)158 int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl, void *data)
159 {
160 	struct nlm_rqst		*call;
161 	int			status;
162 	const struct nlmclnt_operations *nlmclnt_ops = host->h_nlmclnt_ops;
163 
164 	call = nlm_alloc_call(host);
165 	if (call == NULL)
166 		return -ENOMEM;
167 
168 	if (nlmclnt_ops && nlmclnt_ops->nlmclnt_alloc_call)
169 		nlmclnt_ops->nlmclnt_alloc_call(data);
170 
171 	nlmclnt_locks_init_private(fl, host);
172 	if (!fl->fl_u.nfs_fl.owner) {
173 		/* lockowner allocation has failed */
174 		nlmclnt_release_call(call);
175 		return -ENOMEM;
176 	}
177 	/* Set up the argument struct */
178 	nlmclnt_setlockargs(call, fl);
179 	call->a_callback_data = data;
180 
181 	if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
182 		if (fl->fl_type != F_UNLCK) {
183 			call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
184 			status = nlmclnt_lock(call, fl);
185 		} else
186 			status = nlmclnt_unlock(call, fl);
187 	} else if (IS_GETLK(cmd))
188 		status = nlmclnt_test(call, fl);
189 	else
190 		status = -EINVAL;
191 	fl->fl_ops->fl_release_private(fl);
192 	fl->fl_ops = NULL;
193 
194 	dprintk("lockd: clnt proc returns %d\n", status);
195 	return status;
196 }
197 EXPORT_SYMBOL_GPL(nlmclnt_proc);
198 
199 /*
200  * Allocate an NLM RPC call struct
201  */
nlm_alloc_call(struct nlm_host * host)202 struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
203 {
204 	struct nlm_rqst	*call;
205 
206 	for(;;) {
207 		call = kzalloc(sizeof(*call), GFP_KERNEL);
208 		if (call != NULL) {
209 			refcount_set(&call->a_count, 1);
210 			locks_init_lock(&call->a_args.lock.fl);
211 			locks_init_lock(&call->a_res.lock.fl);
212 			call->a_host = nlm_get_host(host);
213 			return call;
214 		}
215 		if (signalled())
216 			break;
217 		printk("nlm_alloc_call: failed, waiting for memory\n");
218 		schedule_timeout_interruptible(5*HZ);
219 	}
220 	return NULL;
221 }
222 
nlmclnt_release_call(struct nlm_rqst * call)223 void nlmclnt_release_call(struct nlm_rqst *call)
224 {
225 	const struct nlmclnt_operations *nlmclnt_ops = call->a_host->h_nlmclnt_ops;
226 
227 	if (!refcount_dec_and_test(&call->a_count))
228 		return;
229 	if (nlmclnt_ops && nlmclnt_ops->nlmclnt_release_call)
230 		nlmclnt_ops->nlmclnt_release_call(call->a_callback_data);
231 	nlmclnt_release_host(call->a_host);
232 	nlmclnt_release_lockargs(call);
233 	kfree(call);
234 }
235 
nlmclnt_rpc_release(void * data)236 static void nlmclnt_rpc_release(void *data)
237 {
238 	nlmclnt_release_call(data);
239 }
240 
nlm_wait_on_grace(wait_queue_head_t * queue)241 static int nlm_wait_on_grace(wait_queue_head_t *queue)
242 {
243 	DEFINE_WAIT(wait);
244 	int status = -EINTR;
245 
246 	prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
247 	if (!signalled ()) {
248 		schedule_timeout(NLMCLNT_GRACE_WAIT);
249 		try_to_freeze();
250 		if (!signalled ())
251 			status = 0;
252 	}
253 	finish_wait(queue, &wait);
254 	return status;
255 }
256 
257 /*
258  * Generic NLM call
259  */
260 static int
nlmclnt_call(const struct cred * cred,struct nlm_rqst * req,u32 proc)261 nlmclnt_call(const struct cred *cred, struct nlm_rqst *req, u32 proc)
262 {
263 	struct nlm_host	*host = req->a_host;
264 	struct rpc_clnt	*clnt;
265 	struct nlm_args	*argp = &req->a_args;
266 	struct nlm_res	*resp = &req->a_res;
267 	struct rpc_message msg = {
268 		.rpc_argp	= argp,
269 		.rpc_resp	= resp,
270 		.rpc_cred	= cred,
271 	};
272 	int		status;
273 
274 	dprintk("lockd: call procedure %d on %s\n",
275 			(int)proc, host->h_name);
276 
277 	do {
278 		if (host->h_reclaiming && !argp->reclaim)
279 			goto in_grace_period;
280 
281 		/* If we have no RPC client yet, create one. */
282 		if ((clnt = nlm_bind_host(host)) == NULL)
283 			return -ENOLCK;
284 		msg.rpc_proc = &clnt->cl_procinfo[proc];
285 
286 		/* Perform the RPC call. If an error occurs, try again */
287 		if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
288 			dprintk("lockd: rpc_call returned error %d\n", -status);
289 			switch (status) {
290 			case -EPROTONOSUPPORT:
291 				status = -EINVAL;
292 				break;
293 			case -ECONNREFUSED:
294 			case -ETIMEDOUT:
295 			case -ENOTCONN:
296 				nlm_rebind_host(host);
297 				status = -EAGAIN;
298 				break;
299 			case -ERESTARTSYS:
300 				return signalled () ? -EINTR : status;
301 			default:
302 				break;
303 			}
304 			break;
305 		} else
306 		if (resp->status == nlm_lck_denied_grace_period) {
307 			dprintk("lockd: server in grace period\n");
308 			if (argp->reclaim) {
309 				printk(KERN_WARNING
310 				     "lockd: spurious grace period reject?!\n");
311 				return -ENOLCK;
312 			}
313 		} else {
314 			if (!argp->reclaim) {
315 				/* We appear to be out of the grace period */
316 				wake_up_all(&host->h_gracewait);
317 			}
318 			dprintk("lockd: server returns status %d\n",
319 				ntohl(resp->status));
320 			return 0;	/* Okay, call complete */
321 		}
322 
323 in_grace_period:
324 		/*
325 		 * The server has rebooted and appears to be in the grace
326 		 * period during which locks are only allowed to be
327 		 * reclaimed.
328 		 * We can only back off and try again later.
329 		 */
330 		status = nlm_wait_on_grace(&host->h_gracewait);
331 	} while (status == 0);
332 
333 	return status;
334 }
335 
336 /*
337  * Generic NLM call, async version.
338  */
__nlm_async_call(struct nlm_rqst * req,u32 proc,struct rpc_message * msg,const struct rpc_call_ops * tk_ops)339 static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
340 {
341 	struct nlm_host	*host = req->a_host;
342 	struct rpc_clnt	*clnt;
343 	struct rpc_task_setup task_setup_data = {
344 		.rpc_message = msg,
345 		.callback_ops = tk_ops,
346 		.callback_data = req,
347 		.flags = RPC_TASK_ASYNC,
348 	};
349 
350 	dprintk("lockd: call procedure %d on %s (async)\n",
351 			(int)proc, host->h_name);
352 
353 	/* If we have no RPC client yet, create one. */
354 	clnt = nlm_bind_host(host);
355 	if (clnt == NULL)
356 		goto out_err;
357 	msg->rpc_proc = &clnt->cl_procinfo[proc];
358 	task_setup_data.rpc_client = clnt;
359 
360         /* bootstrap and kick off the async RPC call */
361 	return rpc_run_task(&task_setup_data);
362 out_err:
363 	tk_ops->rpc_release(req);
364 	return ERR_PTR(-ENOLCK);
365 }
366 
nlm_do_async_call(struct nlm_rqst * req,u32 proc,struct rpc_message * msg,const struct rpc_call_ops * tk_ops)367 static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
368 {
369 	struct rpc_task *task;
370 
371 	task = __nlm_async_call(req, proc, msg, tk_ops);
372 	if (IS_ERR(task))
373 		return PTR_ERR(task);
374 	rpc_put_task(task);
375 	return 0;
376 }
377 
378 /*
379  * NLM asynchronous call.
380  */
nlm_async_call(struct nlm_rqst * req,u32 proc,const struct rpc_call_ops * tk_ops)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_do_async_call(req, proc, &msg, tk_ops);
388 }
389 
nlm_async_reply(struct nlm_rqst * req,u32 proc,const struct rpc_call_ops * tk_ops)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_do_async_call(req, proc, &msg, tk_ops);
396 }
397 
398 /*
399  * NLM client asynchronous call.
400  *
401  * Note that although the calls are asynchronous, and are therefore
402  *      guaranteed to complete, we still always attempt to wait for
403  *      completion in order to be able to correctly track the lock
404  *      state.
405  */
nlmclnt_async_call(const struct cred * cred,struct nlm_rqst * req,u32 proc,const struct rpc_call_ops * tk_ops)406 static int nlmclnt_async_call(const struct cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
407 {
408 	struct rpc_message msg = {
409 		.rpc_argp	= &req->a_args,
410 		.rpc_resp	= &req->a_res,
411 		.rpc_cred	= cred,
412 	};
413 	struct rpc_task *task;
414 	int err;
415 
416 	task = __nlm_async_call(req, proc, &msg, tk_ops);
417 	if (IS_ERR(task))
418 		return PTR_ERR(task);
419 	err = rpc_wait_for_completion_task(task);
420 	rpc_put_task(task);
421 	return err;
422 }
423 
424 /*
425  * TEST for the presence of a conflicting lock
426  */
427 static int
nlmclnt_test(struct nlm_rqst * req,struct file_lock * fl)428 nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
429 {
430 	int	status;
431 
432 	status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
433 	if (status < 0)
434 		goto out;
435 
436 	switch (req->a_res.status) {
437 		case nlm_granted:
438 			fl->fl_type = F_UNLCK;
439 			break;
440 		case nlm_lck_denied:
441 			/*
442 			 * Report the conflicting lock back to the application.
443 			 */
444 			fl->fl_start = req->a_res.lock.fl.fl_start;
445 			fl->fl_end = req->a_res.lock.fl.fl_end;
446 			fl->fl_type = req->a_res.lock.fl.fl_type;
447 			fl->fl_pid = -req->a_res.lock.fl.fl_pid;
448 			break;
449 		default:
450 			status = nlm_stat_to_errno(req->a_res.status);
451 	}
452 out:
453 	nlmclnt_release_call(req);
454 	return status;
455 }
456 
nlmclnt_locks_copy_lock(struct file_lock * new,struct file_lock * fl)457 static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
458 {
459 	spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
460 	new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
461 	new->fl_u.nfs_fl.owner = nlmclnt_get_lockowner(fl->fl_u.nfs_fl.owner);
462 	list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
463 	spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
464 }
465 
nlmclnt_locks_release_private(struct file_lock * fl)466 static void nlmclnt_locks_release_private(struct file_lock *fl)
467 {
468 	spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
469 	list_del(&fl->fl_u.nfs_fl.list);
470 	spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
471 	nlmclnt_put_lockowner(fl->fl_u.nfs_fl.owner);
472 }
473 
474 static const struct file_lock_operations nlmclnt_lock_ops = {
475 	.fl_copy_lock = nlmclnt_locks_copy_lock,
476 	.fl_release_private = nlmclnt_locks_release_private,
477 };
478 
nlmclnt_locks_init_private(struct file_lock * fl,struct nlm_host * host)479 static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
480 {
481 	fl->fl_u.nfs_fl.state = 0;
482 	fl->fl_u.nfs_fl.owner = nlmclnt_find_lockowner(host, fl->fl_owner);
483 	INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
484 	fl->fl_ops = &nlmclnt_lock_ops;
485 }
486 
do_vfs_lock(struct file_lock * fl)487 static int do_vfs_lock(struct file_lock *fl)
488 {
489 	return locks_lock_file_wait(fl->fl_file, fl);
490 }
491 
492 /*
493  * LOCK: Try to create a lock
494  *
495  *			Programmer Harassment Alert
496  *
497  * When given a blocking lock request in a sync RPC call, the HPUX lockd
498  * will faithfully return LCK_BLOCKED but never cares to notify us when
499  * the lock could be granted. This way, our local process could hang
500  * around forever waiting for the callback.
501  *
502  *  Solution A:	Implement busy-waiting
503  *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
504  *
505  * For now I am implementing solution A, because I hate the idea of
506  * re-implementing lockd for a third time in two months. The async
507  * calls shouldn't be too hard to do, however.
508  *
509  * This is one of the lovely things about standards in the NFS area:
510  * they're so soft and squishy you can't really blame HP for doing this.
511  */
512 static int
nlmclnt_lock(struct nlm_rqst * req,struct file_lock * fl)513 nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
514 {
515 	const struct cred *cred = nfs_file_cred(fl->fl_file);
516 	struct nlm_host	*host = req->a_host;
517 	struct nlm_res	*resp = &req->a_res;
518 	struct nlm_wait *block = NULL;
519 	unsigned char fl_flags = fl->fl_flags;
520 	unsigned char fl_type;
521 	int status = -ENOLCK;
522 
523 	if (nsm_monitor(host) < 0)
524 		goto out;
525 	req->a_args.state = nsm_local_state;
526 
527 	fl->fl_flags |= FL_ACCESS;
528 	status = do_vfs_lock(fl);
529 	fl->fl_flags = fl_flags;
530 	if (status < 0)
531 		goto out;
532 
533 	block = nlmclnt_prepare_block(host, fl);
534 again:
535 	/*
536 	 * Initialise resp->status to a valid non-zero value,
537 	 * since 0 == nlm_lck_granted
538 	 */
539 	resp->status = nlm_lck_blocked;
540 	for(;;) {
541 		/* Reboot protection */
542 		fl->fl_u.nfs_fl.state = host->h_state;
543 		status = nlmclnt_call(cred, req, NLMPROC_LOCK);
544 		if (status < 0)
545 			break;
546 		/* Did a reclaimer thread notify us of a server reboot? */
547 		if (resp->status ==  nlm_lck_denied_grace_period)
548 			continue;
549 		if (resp->status != nlm_lck_blocked)
550 			break;
551 		/* Wait on an NLM blocking lock */
552 		status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
553 		if (status < 0)
554 			break;
555 		if (resp->status != nlm_lck_blocked)
556 			break;
557 	}
558 
559 	/* if we were interrupted while blocking, then cancel the lock request
560 	 * and exit
561 	 */
562 	if (resp->status == nlm_lck_blocked) {
563 		if (!req->a_args.block)
564 			goto out_unlock;
565 		if (nlmclnt_cancel(host, req->a_args.block, fl) == 0)
566 			goto out_unblock;
567 	}
568 
569 	if (resp->status == nlm_granted) {
570 		down_read(&host->h_rwsem);
571 		/* Check whether or not the server has rebooted */
572 		if (fl->fl_u.nfs_fl.state != host->h_state) {
573 			up_read(&host->h_rwsem);
574 			goto again;
575 		}
576 		/* Ensure the resulting lock will get added to granted list */
577 		fl->fl_flags |= FL_SLEEP;
578 		if (do_vfs_lock(fl) < 0)
579 			printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
580 		up_read(&host->h_rwsem);
581 		fl->fl_flags = fl_flags;
582 		status = 0;
583 	}
584 	if (status < 0)
585 		goto out_unlock;
586 	/*
587 	 * EAGAIN doesn't make sense for sleeping locks, and in some
588 	 * cases NLM_LCK_DENIED is returned for a permanent error.  So
589 	 * turn it into an ENOLCK.
590 	 */
591 	if (resp->status == nlm_lck_denied && (fl_flags & FL_SLEEP))
592 		status = -ENOLCK;
593 	else
594 		status = nlm_stat_to_errno(resp->status);
595 out_unblock:
596 	nlmclnt_finish_block(block);
597 out:
598 	nlmclnt_release_call(req);
599 	return status;
600 out_unlock:
601 	/* Fatal error: ensure that we remove the lock altogether */
602 	dprintk("lockd: lock attempt ended in fatal error.\n"
603 		"       Attempting to unlock.\n");
604 	nlmclnt_finish_block(block);
605 	fl_type = fl->fl_type;
606 	fl->fl_type = F_UNLCK;
607 	down_read(&host->h_rwsem);
608 	do_vfs_lock(fl);
609 	up_read(&host->h_rwsem);
610 	fl->fl_type = fl_type;
611 	fl->fl_flags = fl_flags;
612 	nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
613 	return status;
614 }
615 
616 /*
617  * RECLAIM: Try to reclaim a lock
618  */
619 int
nlmclnt_reclaim(struct nlm_host * host,struct file_lock * fl,struct nlm_rqst * req)620 nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl,
621 		struct nlm_rqst *req)
622 {
623 	int		status;
624 
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 
630 	/* Set up the argument struct */
631 	nlmclnt_setlockargs(req, fl);
632 	req->a_args.reclaim = 1;
633 
634 	status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK);
635 	if (status >= 0 && req->a_res.status == nlm_granted)
636 		return 0;
637 
638 	printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
639 				"(errno %d, status %d)\n", fl->fl_pid,
640 				status, ntohl(req->a_res.status));
641 
642 	/*
643 	 * FIXME: This is a serious failure. We can
644 	 *
645 	 *  a.	Ignore the problem
646 	 *  b.	Send the owning process some signal (Linux doesn't have
647 	 *	SIGLOST, though...)
648 	 *  c.	Retry the operation
649 	 *
650 	 * Until someone comes up with a simple implementation
651 	 * for b or c, I'll choose option a.
652 	 */
653 
654 	return -ENOLCK;
655 }
656 
657 /*
658  * UNLOCK: remove an existing lock
659  */
660 static int
nlmclnt_unlock(struct nlm_rqst * req,struct file_lock * fl)661 nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
662 {
663 	struct nlm_host	*host = req->a_host;
664 	struct nlm_res	*resp = &req->a_res;
665 	int status;
666 	unsigned char fl_flags = fl->fl_flags;
667 
668 	/*
669 	 * Note: the server is supposed to either grant us the unlock
670 	 * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
671 	 * case, we want to unlock.
672 	 */
673 	fl->fl_flags |= FL_EXISTS;
674 	down_read(&host->h_rwsem);
675 	status = do_vfs_lock(fl);
676 	up_read(&host->h_rwsem);
677 	fl->fl_flags = fl_flags;
678 	if (status == -ENOENT) {
679 		status = 0;
680 		goto out;
681 	}
682 
683 	refcount_inc(&req->a_count);
684 	status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
685 			NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
686 	if (status < 0)
687 		goto out;
688 
689 	if (resp->status == nlm_granted)
690 		goto out;
691 
692 	if (resp->status != nlm_lck_denied_nolocks)
693 		printk("lockd: unexpected unlock status: %d\n",
694 			ntohl(resp->status));
695 	/* What to do now? I'm out of my depth... */
696 	status = -ENOLCK;
697 out:
698 	nlmclnt_release_call(req);
699 	return status;
700 }
701 
nlmclnt_unlock_prepare(struct rpc_task * task,void * data)702 static void nlmclnt_unlock_prepare(struct rpc_task *task, void *data)
703 {
704 	struct nlm_rqst	*req = data;
705 	const struct nlmclnt_operations *nlmclnt_ops = req->a_host->h_nlmclnt_ops;
706 	bool defer_call = false;
707 
708 	if (nlmclnt_ops && nlmclnt_ops->nlmclnt_unlock_prepare)
709 		defer_call = nlmclnt_ops->nlmclnt_unlock_prepare(task, req->a_callback_data);
710 
711 	if (!defer_call)
712 		rpc_call_start(task);
713 }
714 
nlmclnt_unlock_callback(struct rpc_task * task,void * data)715 static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
716 {
717 	struct nlm_rqst	*req = data;
718 	u32 status = ntohl(req->a_res.status);
719 
720 	if (RPC_SIGNALLED(task))
721 		goto die;
722 
723 	if (task->tk_status < 0) {
724 		dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
725 		switch (task->tk_status) {
726 		case -EACCES:
727 		case -EIO:
728 			goto die;
729 		default:
730 			goto retry_rebind;
731 		}
732 	}
733 	if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
734 		rpc_delay(task, NLMCLNT_GRACE_WAIT);
735 		goto retry_unlock;
736 	}
737 	if (status != NLM_LCK_GRANTED)
738 		printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
739 die:
740 	return;
741  retry_rebind:
742 	nlm_rebind_host(req->a_host);
743  retry_unlock:
744 	rpc_restart_call(task);
745 }
746 
747 static const struct rpc_call_ops nlmclnt_unlock_ops = {
748 	.rpc_call_prepare = nlmclnt_unlock_prepare,
749 	.rpc_call_done = nlmclnt_unlock_callback,
750 	.rpc_release = nlmclnt_rpc_release,
751 };
752 
753 /*
754  * Cancel a blocked lock request.
755  * We always use an async RPC call for this in order not to hang a
756  * process that has been Ctrl-C'ed.
757  */
nlmclnt_cancel(struct nlm_host * host,int block,struct file_lock * fl)758 static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
759 {
760 	struct nlm_rqst	*req;
761 	int status;
762 
763 	dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
764 		"       Attempting to cancel lock.\n");
765 
766 	req = nlm_alloc_call(host);
767 	if (!req)
768 		return -ENOMEM;
769 	req->a_flags = RPC_TASK_ASYNC;
770 
771 	nlmclnt_setlockargs(req, fl);
772 	req->a_args.block = block;
773 
774 	refcount_inc(&req->a_count);
775 	status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
776 			NLMPROC_CANCEL, &nlmclnt_cancel_ops);
777 	if (status == 0 && req->a_res.status == nlm_lck_denied)
778 		status = -ENOLCK;
779 	nlmclnt_release_call(req);
780 	return status;
781 }
782 
nlmclnt_cancel_callback(struct rpc_task * task,void * data)783 static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
784 {
785 	struct nlm_rqst	*req = data;
786 	u32 status = ntohl(req->a_res.status);
787 
788 	if (RPC_SIGNALLED(task))
789 		goto die;
790 
791 	if (task->tk_status < 0) {
792 		dprintk("lockd: CANCEL call error %d, retrying.\n",
793 					task->tk_status);
794 		goto retry_cancel;
795 	}
796 
797 	switch (status) {
798 	case NLM_LCK_GRANTED:
799 	case NLM_LCK_DENIED_GRACE_PERIOD:
800 	case NLM_LCK_DENIED:
801 		/* Everything's good */
802 		break;
803 	case NLM_LCK_DENIED_NOLOCKS:
804 		dprintk("lockd: CANCEL failed (server has no locks)\n");
805 		goto retry_cancel;
806 	default:
807 		printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
808 			status);
809 	}
810 
811 die:
812 	return;
813 
814 retry_cancel:
815 	/* Don't ever retry more than 3 times */
816 	if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
817 		goto die;
818 	nlm_rebind_host(req->a_host);
819 	rpc_restart_call(task);
820 	rpc_delay(task, 30 * HZ);
821 }
822 
823 static const struct rpc_call_ops nlmclnt_cancel_ops = {
824 	.rpc_call_done = nlmclnt_cancel_callback,
825 	.rpc_release = nlmclnt_rpc_release,
826 };
827 
828 /*
829  * Convert an NLM status code to a generic kernel errno
830  */
831 static int
nlm_stat_to_errno(__be32 status)832 nlm_stat_to_errno(__be32 status)
833 {
834 	switch(ntohl(status)) {
835 	case NLM_LCK_GRANTED:
836 		return 0;
837 	case NLM_LCK_DENIED:
838 		return -EAGAIN;
839 	case NLM_LCK_DENIED_NOLOCKS:
840 	case NLM_LCK_DENIED_GRACE_PERIOD:
841 		return -ENOLCK;
842 	case NLM_LCK_BLOCKED:
843 		printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
844 		return -ENOLCK;
845 #ifdef CONFIG_LOCKD_V4
846 	case NLM_DEADLCK:
847 		return -EDEADLK;
848 	case NLM_ROFS:
849 		return -EROFS;
850 	case NLM_STALE_FH:
851 		return -ESTALE;
852 	case NLM_FBIG:
853 		return -EOVERFLOW;
854 	case NLM_FAILED:
855 		return -ENOLCK;
856 #endif
857 	}
858 	printk(KERN_NOTICE "lockd: unexpected server status %d\n",
859 		 ntohl(status));
860 	return -ENOLCK;
861 }
862