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/filelock.h>
16#include <linux/nfs_fs.h>
17#include <linux/utsname.h>
18#include <linux/freezer.h>
19#include <linux/sunrpc/clnt.h>
20#include <linux/sunrpc/svc.h>
21#include <linux/lockd/lockd.h>
22
23#include "trace.h"
24
25#define NLMDBG_FACILITY NLMDBG_CLIENT
26#define NLMCLNT_GRACE_WAIT (5*HZ)
27#define NLMCLNT_POLL_TIMEOUT (30*HZ)
28#define NLMCLNT_MAX_RETRIES 3
29
30static int nlmclnt_test(struct nlm_rqst *, struct file_lock *);
31static int nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
32static int nlmclnt_unlock(struct nlm_rqst *, struct file_lock *);
33static int nlm_stat_to_errno(__be32 stat);
34static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host);
35static int nlmclnt_cancel(struct nlm_host *, int , struct file_lock *);
36
37static const struct rpc_call_ops nlmclnt_unlock_ops;
38static const struct rpc_call_ops nlmclnt_cancel_ops;
39
40/*
41 * Cookie counter for NLM requests
42 */
43static atomic_t nlm_cookie = ATOMIC_INIT(0x1234);
44
45void nlmclnt_next_cookie(struct nlm_cookie *c)
46{
47 u32 cookie = atomic_inc_return(v: &nlm_cookie);
48
49 memcpy(c->data, &cookie, 4);
50 c->len=4;
51}
52
53static struct nlm_lockowner *
54nlmclnt_get_lockowner(struct nlm_lockowner *lockowner)
55{
56 refcount_inc(r: &lockowner->count);
57 return lockowner;
58}
59
60static void nlmclnt_put_lockowner(struct nlm_lockowner *lockowner)
61{
62 if (!refcount_dec_and_lock(r: &lockowner->count, lock: &lockowner->host->h_lock))
63 return;
64 list_del(entry: &lockowner->list);
65 spin_unlock(lock: &lockowner->host->h_lock);
66 nlmclnt_release_host(lockowner->host);
67 kfree(objp: lockowner);
68}
69
70static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
71{
72 struct nlm_lockowner *lockowner;
73 list_for_each_entry(lockowner, &host->h_lockowners, list) {
74 if (lockowner->pid == pid)
75 return -EBUSY;
76 }
77 return 0;
78}
79
80static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
81{
82 uint32_t res;
83 do {
84 res = host->h_pidcount++;
85 } while (nlm_pidbusy(host, pid: res) < 0);
86 return res;
87}
88
89static struct nlm_lockowner *__nlmclnt_find_lockowner(struct nlm_host *host, fl_owner_t owner)
90{
91 struct nlm_lockowner *lockowner;
92 list_for_each_entry(lockowner, &host->h_lockowners, list) {
93 if (lockowner->owner != owner)
94 continue;
95 return nlmclnt_get_lockowner(lockowner);
96 }
97 return NULL;
98}
99
100static struct nlm_lockowner *nlmclnt_find_lockowner(struct nlm_host *host, fl_owner_t owner)
101{
102 struct nlm_lockowner *res, *new = NULL;
103
104 spin_lock(lock: &host->h_lock);
105 res = __nlmclnt_find_lockowner(host, owner);
106 if (res == NULL) {
107 spin_unlock(lock: &host->h_lock);
108 new = kmalloc(sizeof(*new), GFP_KERNEL);
109 spin_lock(lock: &host->h_lock);
110 res = __nlmclnt_find_lockowner(host, owner);
111 if (res == NULL && new != NULL) {
112 res = new;
113 refcount_set(r: &new->count, n: 1);
114 new->owner = owner;
115 new->pid = __nlm_alloc_pid(host);
116 new->host = nlm_get_host(host);
117 list_add(new: &new->list, head: &host->h_lockowners);
118 new = NULL;
119 }
120 }
121 spin_unlock(lock: &host->h_lock);
122 kfree(objp: new);
123 return res;
124}
125
126/*
127 * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
128 */
129static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
130{
131 struct nlm_args *argp = &req->a_args;
132 struct nlm_lock *lock = &argp->lock;
133 char *nodename = req->a_host->h_rpcclnt->cl_nodename;
134
135 nlmclnt_next_cookie(c: &argp->cookie);
136 memcpy(&lock->fh, NFS_FH(file_inode(fl->c.flc_file)),
137 sizeof(struct nfs_fh));
138 lock->caller = nodename;
139 lock->oh.data = req->a_owner;
140 lock->oh.len = snprintf(buf: req->a_owner, size: sizeof(req->a_owner), fmt: "%u@%s",
141 (unsigned int)fl->fl_u.nfs_fl.owner->pid,
142 nodename);
143 lock->svid = fl->fl_u.nfs_fl.owner->pid;
144 lock->fl.fl_start = fl->fl_start;
145 lock->fl.fl_end = fl->fl_end;
146 lock->fl.c.flc_type = fl->c.flc_type;
147}
148
149static void nlmclnt_release_lockargs(struct nlm_rqst *req)
150{
151 WARN_ON_ONCE(req->a_args.lock.fl.fl_ops != NULL);
152}
153
154/**
155 * nlmclnt_proc - Perform a single client-side lock request
156 * @host: address of a valid nlm_host context representing the NLM server
157 * @cmd: fcntl-style file lock operation to perform
158 * @fl: address of arguments for the lock operation
159 * @data: address of data to be sent to callback operations
160 *
161 */
162int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl, void *data)
163{
164 struct nlm_rqst *call;
165 int status;
166 const struct nlmclnt_operations *nlmclnt_ops = host->h_nlmclnt_ops;
167
168 call = nlm_alloc_call(host);
169 if (call == NULL)
170 return -ENOMEM;
171
172 if (nlmclnt_ops && nlmclnt_ops->nlmclnt_alloc_call)
173 nlmclnt_ops->nlmclnt_alloc_call(data);
174
175 nlmclnt_locks_init_private(fl, host);
176 if (!fl->fl_u.nfs_fl.owner) {
177 /* lockowner allocation has failed */
178 nlmclnt_release_call(call);
179 return -ENOMEM;
180 }
181 /* Set up the argument struct */
182 nlmclnt_setlockargs(req: call, fl);
183 call->a_callback_data = data;
184
185 if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
186 if (fl->c.flc_type != F_UNLCK) {
187 call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
188 status = nlmclnt_lock(call, fl);
189 } else
190 status = nlmclnt_unlock(call, fl);
191 } else if (IS_GETLK(cmd))
192 status = nlmclnt_test(call, fl);
193 else
194 status = -EINVAL;
195 fl->fl_ops->fl_release_private(fl);
196 fl->fl_ops = NULL;
197
198 dprintk("lockd: clnt proc returns %d\n", status);
199 return status;
200}
201EXPORT_SYMBOL_GPL(nlmclnt_proc);
202
203/*
204 * Allocate an NLM RPC call struct
205 */
206struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
207{
208 struct nlm_rqst *call;
209
210 for(;;) {
211 call = kzalloc(sizeof(*call), GFP_KERNEL);
212 if (call != NULL) {
213 refcount_set(r: &call->a_count, n: 1);
214 locks_init_lock(&call->a_args.lock.fl);
215 locks_init_lock(&call->a_res.lock.fl);
216 call->a_host = nlm_get_host(host);
217 return call;
218 }
219 if (signalled())
220 break;
221 printk("nlm_alloc_call: failed, waiting for memory\n");
222 schedule_timeout_interruptible(timeout: 5*HZ);
223 }
224 return NULL;
225}
226
227void nlmclnt_release_call(struct nlm_rqst *call)
228{
229 const struct nlmclnt_operations *nlmclnt_ops = call->a_host->h_nlmclnt_ops;
230
231 if (!refcount_dec_and_test(r: &call->a_count))
232 return;
233 if (nlmclnt_ops && nlmclnt_ops->nlmclnt_release_call)
234 nlmclnt_ops->nlmclnt_release_call(call->a_callback_data);
235 nlmclnt_release_host(call->a_host);
236 nlmclnt_release_lockargs(req: call);
237 kfree(objp: call);
238}
239
240static void nlmclnt_rpc_release(void *data)
241{
242 nlmclnt_release_call(call: data);
243}
244
245static int nlm_wait_on_grace(wait_queue_head_t *queue)
246{
247 DEFINE_WAIT(wait);
248 int status = -EINTR;
249
250 prepare_to_wait(wq_head: queue, wq_entry: &wait, TASK_INTERRUPTIBLE);
251 if (!signalled ()) {
252 schedule_timeout(NLMCLNT_GRACE_WAIT);
253 try_to_freeze();
254 if (!signalled ())
255 status = 0;
256 }
257 finish_wait(wq_head: queue, wq_entry: &wait);
258 return status;
259}
260
261/*
262 * Generic NLM call
263 */
264static int
265nlmclnt_call(const struct cred *cred, struct nlm_rqst *req, u32 proc)
266{
267 struct nlm_host *host = req->a_host;
268 struct rpc_clnt *clnt;
269 struct nlm_args *argp = &req->a_args;
270 struct nlm_res *resp = &req->a_res;
271 struct rpc_message msg = {
272 .rpc_argp = argp,
273 .rpc_resp = resp,
274 .rpc_cred = cred,
275 };
276 int status;
277
278 dprintk("lockd: call procedure %d on %s\n",
279 (int)proc, host->h_name);
280
281 do {
282 if (host->h_reclaiming && !argp->reclaim)
283 goto in_grace_period;
284
285 /* If we have no RPC client yet, create one. */
286 if ((clnt = nlm_bind_host(host)) == NULL)
287 return -ENOLCK;
288 msg.rpc_proc = &clnt->cl_procinfo[proc];
289
290 /* Perform the RPC call. If an error occurs, try again */
291 if ((status = rpc_call_sync(clnt, msg: &msg, flags: 0)) < 0) {
292 dprintk("lockd: rpc_call returned error %d\n", -status);
293 switch (status) {
294 case -EPROTONOSUPPORT:
295 status = -EINVAL;
296 break;
297 case -ECONNREFUSED:
298 case -ETIMEDOUT:
299 case -ENOTCONN:
300 nlm_rebind_host(host);
301 status = -EAGAIN;
302 break;
303 case -ERESTARTSYS:
304 return signalled () ? -EINTR : status;
305 default:
306 break;
307 }
308 break;
309 } else
310 if (resp->status == nlm_lck_denied_grace_period) {
311 dprintk("lockd: server in grace period\n");
312 if (argp->reclaim) {
313 printk(KERN_WARNING
314 "lockd: spurious grace period reject?!\n");
315 return -ENOLCK;
316 }
317 } else {
318 if (!argp->reclaim) {
319 /* We appear to be out of the grace period */
320 wake_up_all(&host->h_gracewait);
321 }
322 dprintk("lockd: server returns status %d\n",
323 ntohl(resp->status));
324 return 0; /* Okay, call complete */
325 }
326
327in_grace_period:
328 /*
329 * The server has rebooted and appears to be in the grace
330 * period during which locks are only allowed to be
331 * reclaimed.
332 * We can only back off and try again later.
333 */
334 status = nlm_wait_on_grace(queue: &host->h_gracewait);
335 } while (status == 0);
336
337 return status;
338}
339
340/*
341 * Generic NLM call, async version.
342 */
343static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
344{
345 struct nlm_host *host = req->a_host;
346 struct rpc_clnt *clnt;
347 struct rpc_task_setup task_setup_data = {
348 .rpc_message = msg,
349 .callback_ops = tk_ops,
350 .callback_data = req,
351 .flags = RPC_TASK_ASYNC,
352 };
353
354 dprintk("lockd: call procedure %d on %s (async)\n",
355 (int)proc, host->h_name);
356
357 /* If we have no RPC client yet, create one. */
358 clnt = nlm_bind_host(host);
359 if (clnt == NULL)
360 goto out_err;
361 msg->rpc_proc = &clnt->cl_procinfo[proc];
362 task_setup_data.rpc_client = clnt;
363
364 /* bootstrap and kick off the async RPC call */
365 return rpc_run_task(&task_setup_data);
366out_err:
367 tk_ops->rpc_release(req);
368 return ERR_PTR(error: -ENOLCK);
369}
370
371static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
372{
373 struct rpc_task *task;
374
375 task = __nlm_async_call(req, proc, msg, tk_ops);
376 if (IS_ERR(ptr: task))
377 return PTR_ERR(ptr: task);
378 rpc_put_task(task);
379 return 0;
380}
381
382/*
383 * NLM asynchronous call.
384 */
385int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
386{
387 struct rpc_message msg = {
388 .rpc_argp = &req->a_args,
389 .rpc_resp = &req->a_res,
390 };
391 return nlm_do_async_call(req, proc, msg: &msg, tk_ops);
392}
393
394int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
395{
396 struct rpc_message msg = {
397 .rpc_argp = &req->a_res,
398 };
399 return nlm_do_async_call(req, proc, msg: &msg, tk_ops);
400}
401
402/*
403 * NLM client asynchronous call.
404 *
405 * Note that although the calls are asynchronous, and are therefore
406 * guaranteed to complete, we still always attempt to wait for
407 * completion in order to be able to correctly track the lock
408 * state.
409 */
410static int nlmclnt_async_call(const struct cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
411{
412 struct rpc_message msg = {
413 .rpc_argp = &req->a_args,
414 .rpc_resp = &req->a_res,
415 .rpc_cred = cred,
416 };
417 struct rpc_task *task;
418 int err;
419
420 task = __nlm_async_call(req, proc, msg: &msg, tk_ops);
421 if (IS_ERR(ptr: task))
422 return PTR_ERR(ptr: task);
423 err = rpc_wait_for_completion_task(task);
424 rpc_put_task(task);
425 return err;
426}
427
428/*
429 * TEST for the presence of a conflicting lock
430 */
431static int
432nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
433{
434 int status;
435
436 status = nlmclnt_call(cred: nfs_file_cred(file: fl->c.flc_file), req,
437 NLMPROC_TEST);
438 if (status < 0)
439 goto out;
440
441 switch (req->a_res.status) {
442 case nlm_granted:
443 fl->c.flc_type = F_UNLCK;
444 break;
445 case nlm_lck_denied:
446 /*
447 * Report the conflicting lock back to the application.
448 */
449 fl->fl_start = req->a_res.lock.fl.fl_start;
450 fl->fl_end = req->a_res.lock.fl.fl_end;
451 fl->c.flc_type = req->a_res.lock.fl.c.flc_type;
452 fl->c.flc_pid = -req->a_res.lock.fl.c.flc_pid;
453 break;
454 default:
455 status = nlm_stat_to_errno(stat: req->a_res.status);
456 }
457out:
458 trace_nlmclnt_test(lock: &req->a_args.lock,
459 addr: (const struct sockaddr *)&req->a_host->h_addr,
460 addrlen: req->a_host->h_addrlen, status: req->a_res.status);
461 nlmclnt_release_call(call: req);
462 return status;
463}
464
465static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
466{
467 spin_lock(lock: &fl->fl_u.nfs_fl.owner->host->h_lock);
468 new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
469 new->fl_u.nfs_fl.owner = nlmclnt_get_lockowner(lockowner: fl->fl_u.nfs_fl.owner);
470 list_add_tail(new: &new->fl_u.nfs_fl.list, head: &fl->fl_u.nfs_fl.owner->host->h_granted);
471 spin_unlock(lock: &fl->fl_u.nfs_fl.owner->host->h_lock);
472}
473
474static void nlmclnt_locks_release_private(struct file_lock *fl)
475{
476 spin_lock(lock: &fl->fl_u.nfs_fl.owner->host->h_lock);
477 list_del(entry: &fl->fl_u.nfs_fl.list);
478 spin_unlock(lock: &fl->fl_u.nfs_fl.owner->host->h_lock);
479 nlmclnt_put_lockowner(lockowner: fl->fl_u.nfs_fl.owner);
480}
481
482static const struct file_lock_operations nlmclnt_lock_ops = {
483 .fl_copy_lock = nlmclnt_locks_copy_lock,
484 .fl_release_private = nlmclnt_locks_release_private,
485};
486
487static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
488{
489 fl->fl_u.nfs_fl.state = 0;
490 fl->fl_u.nfs_fl.owner = nlmclnt_find_lockowner(host,
491 owner: fl->c.flc_owner);
492 INIT_LIST_HEAD(list: &fl->fl_u.nfs_fl.list);
493 fl->fl_ops = &nlmclnt_lock_ops;
494}
495
496static int do_vfs_lock(struct file_lock *fl)
497{
498 return locks_lock_file_wait(filp: fl->c.flc_file, fl);
499}
500
501/*
502 * LOCK: Try to create a lock
503 *
504 * Programmer Harassment Alert
505 *
506 * When given a blocking lock request in a sync RPC call, the HPUX lockd
507 * will faithfully return LCK_BLOCKED but never cares to notify us when
508 * the lock could be granted. This way, our local process could hang
509 * around forever waiting for the callback.
510 *
511 * Solution A: Implement busy-waiting
512 * Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
513 *
514 * For now I am implementing solution A, because I hate the idea of
515 * re-implementing lockd for a third time in two months. The async
516 * calls shouldn't be too hard to do, however.
517 *
518 * This is one of the lovely things about standards in the NFS area:
519 * they're so soft and squishy you can't really blame HP for doing this.
520 */
521static int
522nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
523{
524 const struct cred *cred = nfs_file_cred(file: fl->c.flc_file);
525 struct nlm_host *host = req->a_host;
526 struct nlm_res *resp = &req->a_res;
527 struct nlm_wait block;
528 unsigned char flags = fl->c.flc_flags;
529 unsigned char type;
530 __be32 b_status;
531 int status = -ENOLCK;
532
533 if (nsm_monitor(host) < 0)
534 goto out;
535 req->a_args.state = nsm_local_state;
536
537 fl->c.flc_flags |= FL_ACCESS;
538 status = do_vfs_lock(fl);
539 fl->c.flc_flags = flags;
540 if (status < 0)
541 goto out;
542
543 nlmclnt_prepare_block(block: &block, host, fl);
544again:
545 /*
546 * Initialise resp->status to a valid non-zero value,
547 * since 0 == nlm_lck_granted
548 */
549 resp->status = nlm_lck_blocked;
550
551 /*
552 * A GRANTED callback can come at any time -- even before the reply
553 * to the LOCK request arrives, so we queue the wait before
554 * requesting the lock.
555 */
556 nlmclnt_queue_block(block: &block);
557 for (;;) {
558 /* Reboot protection */
559 fl->fl_u.nfs_fl.state = host->h_state;
560 status = nlmclnt_call(cred, req, NLMPROC_LOCK);
561 if (status < 0)
562 break;
563 /* Did a reclaimer thread notify us of a server reboot? */
564 if (resp->status == nlm_lck_denied_grace_period)
565 continue;
566 if (resp->status != nlm_lck_blocked)
567 break;
568 /* Wait on an NLM blocking lock */
569 status = nlmclnt_wait(block: &block, req, NLMCLNT_POLL_TIMEOUT);
570 if (status < 0)
571 break;
572 if (block.b_status != nlm_lck_blocked)
573 break;
574 }
575 b_status = nlmclnt_dequeue_block(block: &block);
576 if (resp->status == nlm_lck_blocked)
577 resp->status = b_status;
578
579 /* if we were interrupted while blocking, then cancel the lock request
580 * and exit
581 */
582 if (resp->status == nlm_lck_blocked) {
583 if (!req->a_args.block)
584 goto out_unlock;
585 if (nlmclnt_cancel(host, req->a_args.block, fl) == 0)
586 goto out;
587 }
588
589 if (resp->status == nlm_granted) {
590 down_read(sem: &host->h_rwsem);
591 /* Check whether or not the server has rebooted */
592 if (fl->fl_u.nfs_fl.state != host->h_state) {
593 up_read(sem: &host->h_rwsem);
594 goto again;
595 }
596 /* Ensure the resulting lock will get added to granted list */
597 fl->c.flc_flags |= FL_SLEEP;
598 if (do_vfs_lock(fl) < 0)
599 printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
600 up_read(sem: &host->h_rwsem);
601 fl->c.flc_flags = flags;
602 status = 0;
603 }
604 if (status < 0)
605 goto out_unlock;
606 /*
607 * EAGAIN doesn't make sense for sleeping locks, and in some
608 * cases NLM_LCK_DENIED is returned for a permanent error. So
609 * turn it into an ENOLCK.
610 */
611 if (resp->status == nlm_lck_denied && (flags & FL_SLEEP))
612 status = -ENOLCK;
613 else
614 status = nlm_stat_to_errno(stat: resp->status);
615out:
616 trace_nlmclnt_lock(lock: &req->a_args.lock,
617 addr: (const struct sockaddr *)&req->a_host->h_addr,
618 addrlen: req->a_host->h_addrlen, status: req->a_res.status);
619 nlmclnt_release_call(call: req);
620 return status;
621out_unlock:
622 /* Fatal error: ensure that we remove the lock altogether */
623 trace_nlmclnt_lock(lock: &req->a_args.lock,
624 addr: (const struct sockaddr *)&req->a_host->h_addr,
625 addrlen: req->a_host->h_addrlen, status: req->a_res.status);
626 dprintk("lockd: lock attempt ended in fatal error.\n"
627 " Attempting to unlock.\n");
628 type = fl->c.flc_type;
629 fl->c.flc_type = F_UNLCK;
630 down_read(sem: &host->h_rwsem);
631 do_vfs_lock(fl);
632 up_read(sem: &host->h_rwsem);
633 fl->c.flc_type = type;
634 fl->c.flc_flags = flags;
635 nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, tk_ops: &nlmclnt_unlock_ops);
636 return status;
637}
638
639/*
640 * RECLAIM: Try to reclaim a lock
641 */
642int
643nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl,
644 struct nlm_rqst *req)
645{
646 int status;
647
648 memset(req, 0, sizeof(*req));
649 locks_init_lock(&req->a_args.lock.fl);
650 locks_init_lock(&req->a_res.lock.fl);
651 req->a_host = host;
652
653 /* Set up the argument struct */
654 nlmclnt_setlockargs(req, fl);
655 req->a_args.reclaim = 1;
656
657 status = nlmclnt_call(cred: nfs_file_cred(file: fl->c.flc_file), req,
658 NLMPROC_LOCK);
659 if (status >= 0 && req->a_res.status == nlm_granted)
660 return 0;
661
662 printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
663 "(errno %d, status %d)\n",
664 fl->c.flc_pid,
665 status, ntohl(req->a_res.status));
666
667 /*
668 * FIXME: This is a serious failure. We can
669 *
670 * a. Ignore the problem
671 * b. Send the owning process some signal (Linux doesn't have
672 * SIGLOST, though...)
673 * c. Retry the operation
674 *
675 * Until someone comes up with a simple implementation
676 * for b or c, I'll choose option a.
677 */
678
679 return -ENOLCK;
680}
681
682/*
683 * UNLOCK: remove an existing lock
684 */
685static int
686nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
687{
688 struct nlm_host *host = req->a_host;
689 struct nlm_res *resp = &req->a_res;
690 int status;
691 unsigned char flags = fl->c.flc_flags;
692
693 /*
694 * Note: the server is supposed to either grant us the unlock
695 * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
696 * case, we want to unlock.
697 */
698 fl->c.flc_flags |= FL_EXISTS;
699 down_read(sem: &host->h_rwsem);
700 status = do_vfs_lock(fl);
701 up_read(sem: &host->h_rwsem);
702 fl->c.flc_flags = flags;
703 if (status == -ENOENT) {
704 status = 0;
705 goto out;
706 }
707
708 refcount_inc(r: &req->a_count);
709 status = nlmclnt_async_call(cred: nfs_file_cred(file: fl->c.flc_file), req,
710 NLMPROC_UNLOCK, tk_ops: &nlmclnt_unlock_ops);
711 if (status < 0)
712 goto out;
713
714 if (resp->status == nlm_granted)
715 goto out;
716
717 if (resp->status != nlm_lck_denied_nolocks)
718 printk("lockd: unexpected unlock status: %d\n",
719 ntohl(resp->status));
720 /* What to do now? I'm out of my depth... */
721 status = -ENOLCK;
722out:
723 trace_nlmclnt_unlock(lock: &req->a_args.lock,
724 addr: (const struct sockaddr *)&req->a_host->h_addr,
725 addrlen: req->a_host->h_addrlen, status: req->a_res.status);
726 nlmclnt_release_call(call: req);
727 return status;
728}
729
730static void nlmclnt_unlock_prepare(struct rpc_task *task, void *data)
731{
732 struct nlm_rqst *req = data;
733 const struct nlmclnt_operations *nlmclnt_ops = req->a_host->h_nlmclnt_ops;
734 bool defer_call = false;
735
736 if (nlmclnt_ops && nlmclnt_ops->nlmclnt_unlock_prepare)
737 defer_call = nlmclnt_ops->nlmclnt_unlock_prepare(task, req->a_callback_data);
738
739 if (!defer_call)
740 rpc_call_start(task);
741}
742
743static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
744{
745 struct nlm_rqst *req = data;
746 u32 status = ntohl(req->a_res.status);
747
748 if (RPC_SIGNALLED(task))
749 goto die;
750
751 if (task->tk_status < 0) {
752 dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
753 switch (task->tk_status) {
754 case -EACCES:
755 case -EIO:
756 goto die;
757 default:
758 goto retry_rebind;
759 }
760 }
761 if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
762 rpc_delay(task, NLMCLNT_GRACE_WAIT);
763 goto retry_unlock;
764 }
765 if (status != NLM_LCK_GRANTED)
766 printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
767die:
768 return;
769 retry_rebind:
770 nlm_rebind_host(req->a_host);
771 retry_unlock:
772 rpc_restart_call(task);
773}
774
775static const struct rpc_call_ops nlmclnt_unlock_ops = {
776 .rpc_call_prepare = nlmclnt_unlock_prepare,
777 .rpc_call_done = nlmclnt_unlock_callback,
778 .rpc_release = nlmclnt_rpc_release,
779};
780
781/*
782 * Cancel a blocked lock request.
783 * We always use an async RPC call for this in order not to hang a
784 * process that has been Ctrl-C'ed.
785 */
786static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
787{
788 struct nlm_rqst *req;
789 int status;
790
791 dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
792 " Attempting to cancel lock.\n");
793
794 req = nlm_alloc_call(host);
795 if (!req)
796 return -ENOMEM;
797 req->a_flags = RPC_TASK_ASYNC;
798
799 nlmclnt_setlockargs(req, fl);
800 req->a_args.block = block;
801
802 refcount_inc(r: &req->a_count);
803 status = nlmclnt_async_call(cred: nfs_file_cred(file: fl->c.flc_file), req,
804 NLMPROC_CANCEL, tk_ops: &nlmclnt_cancel_ops);
805 if (status == 0 && req->a_res.status == nlm_lck_denied)
806 status = -ENOLCK;
807 nlmclnt_release_call(call: req);
808 return status;
809}
810
811static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
812{
813 struct nlm_rqst *req = data;
814 u32 status = ntohl(req->a_res.status);
815
816 if (RPC_SIGNALLED(task))
817 goto die;
818
819 if (task->tk_status < 0) {
820 dprintk("lockd: CANCEL call error %d, retrying.\n",
821 task->tk_status);
822 goto retry_cancel;
823 }
824
825 switch (status) {
826 case NLM_LCK_GRANTED:
827 case NLM_LCK_DENIED_GRACE_PERIOD:
828 case NLM_LCK_DENIED:
829 /* Everything's good */
830 break;
831 case NLM_LCK_DENIED_NOLOCKS:
832 dprintk("lockd: CANCEL failed (server has no locks)\n");
833 goto retry_cancel;
834 default:
835 printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
836 status);
837 }
838
839die:
840 return;
841
842retry_cancel:
843 /* Don't ever retry more than 3 times */
844 if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
845 goto die;
846 nlm_rebind_host(req->a_host);
847 rpc_restart_call(task);
848 rpc_delay(task, 30 * HZ);
849}
850
851static const struct rpc_call_ops nlmclnt_cancel_ops = {
852 .rpc_call_done = nlmclnt_cancel_callback,
853 .rpc_release = nlmclnt_rpc_release,
854};
855
856/*
857 * Convert an NLM status code to a generic kernel errno
858 */
859static int
860nlm_stat_to_errno(__be32 status)
861{
862 switch(ntohl(status)) {
863 case NLM_LCK_GRANTED:
864 return 0;
865 case NLM_LCK_DENIED:
866 return -EAGAIN;
867 case NLM_LCK_DENIED_NOLOCKS:
868 case NLM_LCK_DENIED_GRACE_PERIOD:
869 return -ENOLCK;
870 case NLM_LCK_BLOCKED:
871 printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
872 return -ENOLCK;
873#ifdef CONFIG_LOCKD_V4
874 case NLM_DEADLCK:
875 return -EDEADLK;
876 case NLM_ROFS:
877 return -EROFS;
878 case NLM_STALE_FH:
879 return -ESTALE;
880 case NLM_FBIG:
881 return -EOVERFLOW;
882 case NLM_FAILED:
883 return -ENOLCK;
884#endif
885 }
886 printk(KERN_NOTICE "lockd: unexpected server status %d\n",
887 ntohl(status));
888 return -ENOLCK;
889}
890

source code of linux/fs/lockd/clntproc.c