1/*
  2 * linux/fs/lockd/svclock.c
  3 *
  4 * Handling of server-side locks, mostly of the blocked variety.
  5 * This is the ugliest part of lockd because we tread on very thin ice.
  6 * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
  7 * IMNSHO introducing the grant callback into the NLM protocol was one
  8 * of the worst ideas Sun ever had. Except maybe for the idea of doing
  9 * NFS file locking at all.
 10 *
 11 * I'm trying hard to avoid race conditions by protecting most accesses
 12 * to a file's list of blocked locks through a semaphore. The global
 13 * list of blocked locks is not protected in this fashion however.
 14 * Therefore, some functions (such as the RPC callback for the async grant
 15 * call) move blocked locks towards the head of the list *while some other
 16 * process might be traversing it*. This should not be a problem in
 17 * practice, because this will only cause functions traversing the list
 18 * to visit some blocks twice.
 19 *
 20 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
 21 */
 22
 23#include <linux/types.h>
 24#include <linux/slab.h>
 25#include <linux/errno.h>
 26#include <linux/kernel.h>
 27#include <linux/sched.h>
 28#include <linux/sunrpc/clnt.h>
 29#include <linux/sunrpc/svc_xprt.h>
 30#include <linux/lockd/nlm.h>
 31#include <linux/lockd/lockd.h>
 32#include <linux/kthread.h>
 33
 34#define NLMDBG_FACILITY		NLMDBG_SVCLOCK
 35
 36#ifdef CONFIG_LOCKD_V4
 37#define nlm_deadlock	nlm4_deadlock
 38#else
 39#define nlm_deadlock	nlm_lck_denied
 40#endif
 41
 42static void nlmsvc_release_block(struct nlm_block *block);
 43static void	nlmsvc_insert_block(struct nlm_block *block, unsigned long);
 44static void	nlmsvc_remove_block(struct nlm_block *block);
 45
 46static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
 47static void nlmsvc_freegrantargs(struct nlm_rqst *call);
 48static const struct rpc_call_ops nlmsvc_grant_ops;
 
 49
 50/*
 51 * The list of blocked locks to retry
 52 */
 53static LIST_HEAD(nlm_blocked);
 54static DEFINE_SPINLOCK(nlm_blocked_lock);
 55
 56#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 57static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
 58{
 59	/*
 60	 * We can get away with a static buffer because this is only called
 61	 * from lockd, which is single-threaded.
 62	 */
 63	static char buf[2*NLM_MAXCOOKIELEN+1];
 64	unsigned int i, len = sizeof(buf);
 65	char *p = buf;
 66
 67	len--;	/* allow for trailing \0 */
 68	if (len < 3)
 69		return "???";
 70	for (i = 0 ; i < cookie->len ; i++) {
 71		if (len < 2) {
 72			strcpy(p-3, "...");
 73			break;
 74		}
 75		sprintf(p, "%02x", cookie->data[i]);
 76		p += 2;
 77		len -= 2;
 78	}
 79	*p = '\0';
 80
 81	return buf;
 82}
 83#endif
 84
 85/*
 86 * Insert a blocked lock into the global list
 87 */
 88static void
 89nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
 90{
 91	struct nlm_block *b;
 92	struct list_head *pos;
 93
 94	dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
 95	if (list_empty(&block->b_list)) {
 96		kref_get(&block->b_count);
 97	} else {
 98		list_del_init(&block->b_list);
 99	}
100
101	pos = &nlm_blocked;
102	if (when != NLM_NEVER) {
103		if ((when += jiffies) == NLM_NEVER)
104			when ++;
105		list_for_each(pos, &nlm_blocked) {
106			b = list_entry(pos, struct nlm_block, b_list);
107			if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
108				break;
109		}
110		/* On normal exit from the loop, pos == &nlm_blocked,
111		 * so we will be adding to the end of the list - good
112		 */
113	}
114
115	list_add_tail(&block->b_list, pos);
116	block->b_when = when;
117}
118
119static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
120{
121	spin_lock(&nlm_blocked_lock);
122	nlmsvc_insert_block_locked(block, when);
123	spin_unlock(&nlm_blocked_lock);
124}
125
126/*
127 * Remove a block from the global list
128 */
129static inline void
130nlmsvc_remove_block(struct nlm_block *block)
131{
132	if (!list_empty(&block->b_list)) {
133		spin_lock(&nlm_blocked_lock);
134		list_del_init(&block->b_list);
135		spin_unlock(&nlm_blocked_lock);
136		nlmsvc_release_block(block);
137	}
138}
139
140/*
141 * Find a block for a given lock
142 */
143static struct nlm_block *
144nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
145{
146	struct nlm_block	*block;
147	struct file_lock	*fl;
148
149	dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
150				file, lock->fl.fl_pid,
151				(long long)lock->fl.fl_start,
152				(long long)lock->fl.fl_end, lock->fl.fl_type);
153	list_for_each_entry(block, &nlm_blocked, b_list) {
154		fl = &block->b_call->a_args.lock.fl;
155		dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
156				block->b_file, fl->fl_pid,
157				(long long)fl->fl_start,
158				(long long)fl->fl_end, fl->fl_type,
159				nlmdbg_cookie2a(&block->b_call->a_args.cookie));
160		if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
161			kref_get(&block->b_count);
162			return block;
163		}
164	}
165
166	return NULL;
167}
168
169static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
170{
171	if (a->len != b->len)
172		return 0;
173	if (memcmp(a->data, b->data, a->len))
174		return 0;
175	return 1;
176}
177
178/*
179 * Find a block with a given NLM cookie.
180 */
181static inline struct nlm_block *
182nlmsvc_find_block(struct nlm_cookie *cookie)
183{
184	struct nlm_block *block;
185
186	list_for_each_entry(block, &nlm_blocked, b_list) {
187		if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
188			goto found;
189	}
190
191	return NULL;
192
193found:
194	dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
195	kref_get(&block->b_count);
196	return block;
197}
198
199/*
200 * Create a block and initialize it.
201 *
202 * Note: we explicitly set the cookie of the grant reply to that of
203 * the blocked lock request. The spec explicitly mentions that the client
204 * should _not_ rely on the callback containing the same cookie as the
205 * request, but (as I found out later) that's because some implementations
206 * do just this. Never mind the standards comittees, they support our
207 * logging industries.
208 *
209 * 10 years later: I hope we can safely ignore these old and broken
210 * clients by now. Let's fix this so we can uniquely identify an incoming
211 * GRANTED_RES message by cookie, without having to rely on the client's IP
212 * address. --okir
213 */
214static struct nlm_block *
215nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
216		    struct nlm_file *file, struct nlm_lock *lock,
217		    struct nlm_cookie *cookie)
218{
219	struct nlm_block	*block;
220	struct nlm_rqst		*call = NULL;
221
 
222	call = nlm_alloc_call(host);
223	if (call == NULL)
224		return NULL;
225
226	/* Allocate memory for block, and initialize arguments */
227	block = kzalloc(sizeof(*block), GFP_KERNEL);
228	if (block == NULL)
229		goto failed;
230	kref_init(&block->b_count);
231	INIT_LIST_HEAD(&block->b_list);
232	INIT_LIST_HEAD(&block->b_flist);
233
234	if (!nlmsvc_setgrantargs(call, lock))
235		goto failed_free;
236
237	/* Set notifier function for VFS, and init args */
238	call->a_args.lock.fl.fl_flags |= FL_SLEEP;
239	call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
240	nlmclnt_next_cookie(&call->a_args.cookie);
241
242	dprintk("lockd: created block %p...\n", block);
243
244	/* Create and initialize the block */
245	block->b_daemon = rqstp->rq_server;
246	block->b_host   = host;
247	block->b_file   = file;
 
248	file->f_count++;
249
250	/* Add to file's list of blocks */
251	list_add(&block->b_flist, &file->f_blocks);
252
253	/* Set up RPC arguments for callback */
254	block->b_call = call;
255	call->a_flags   = RPC_TASK_ASYNC;
256	call->a_block = block;
257
258	return block;
259
260failed_free:
261	kfree(block);
262failed:
263	nlmsvc_release_call(call);
264	return NULL;
265}
266
267/*
268 * Delete a block.
269 * It is the caller's responsibility to check whether the file
270 * can be closed hereafter.
271 */
272static int nlmsvc_unlink_block(struct nlm_block *block)
273{
274	int status;
275	dprintk("lockd: unlinking block %p...\n", block);
276
277	/* Remove block from list */
278	status = posix_unblock_lock(&block->b_call->a_args.lock.fl);
279	nlmsvc_remove_block(block);
280	return status;
281}
282
283static void nlmsvc_free_block(struct kref *kref)
284{
285	struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
286	struct nlm_file		*file = block->b_file;
287
288	dprintk("lockd: freeing block %p...\n", block);
289
290	/* Remove block from file's list of blocks */
 
291	list_del_init(&block->b_flist);
292	mutex_unlock(&file->f_mutex);
293
294	nlmsvc_freegrantargs(block->b_call);
295	nlmsvc_release_call(block->b_call);
296	nlm_release_file(block->b_file);
 
297	kfree(block);
298}
299
300static void nlmsvc_release_block(struct nlm_block *block)
301{
302	if (block != NULL)
303		kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
304}
305
306/*
307 * Loop over all blocks and delete blocks held by
308 * a matching host.
309 */
310void nlmsvc_traverse_blocks(struct nlm_host *host,
311			struct nlm_file *file,
312			nlm_host_match_fn_t match)
313{
314	struct nlm_block *block, *next;
315
316restart:
317	mutex_lock(&file->f_mutex);
318	list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
319		if (!match(block->b_host, host))
320			continue;
321		/* Do not destroy blocks that are not on
322		 * the global retry list - why? */
323		if (list_empty(&block->b_list))
324			continue;
325		kref_get(&block->b_count);
326		mutex_unlock(&file->f_mutex);
327		nlmsvc_unlink_block(block);
328		nlmsvc_release_block(block);
329		goto restart;
330	}
331	mutex_unlock(&file->f_mutex);
332}
333
334/*
335 * Initialize arguments for GRANTED call. The nlm_rqst structure
336 * has been cleared already.
337 */
338static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
339{
340	locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
341	memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
342	call->a_args.lock.caller = utsname()->nodename;
343	call->a_args.lock.oh.len = lock->oh.len;
344
345	/* set default data area */
346	call->a_args.lock.oh.data = call->a_owner;
347	call->a_args.lock.svid = lock->fl.fl_pid;
348
349	if (lock->oh.len > NLMCLNT_OHSIZE) {
350		void *data = kmalloc(lock->oh.len, GFP_KERNEL);
351		if (!data)
352			return 0;
353		call->a_args.lock.oh.data = (u8 *) data;
354	}
355
356	memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
357	return 1;
358}
359
360static void nlmsvc_freegrantargs(struct nlm_rqst *call)
361{
362	if (call->a_args.lock.oh.data != call->a_owner)
363		kfree(call->a_args.lock.oh.data);
364
365	locks_release_private(&call->a_args.lock.fl);
366}
367
368/*
369 * Deferred lock request handling for non-blocking lock
370 */
371static __be32
372nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
373{
374	__be32 status = nlm_lck_denied_nolocks;
375
376	block->b_flags |= B_QUEUED;
377
378	nlmsvc_insert_block(block, NLM_TIMEOUT);
379
380	block->b_cache_req = &rqstp->rq_chandle;
381	if (rqstp->rq_chandle.defer) {
382		block->b_deferred_req =
383			rqstp->rq_chandle.defer(block->b_cache_req);
384		if (block->b_deferred_req != NULL)
385			status = nlm_drop_reply;
386	}
387	dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
388		block, block->b_flags, ntohl(status));
389
390	return status;
391}
392
393/*
394 * Attempt to establish a lock, and if it can't be granted, block it
395 * if required.
396 */
397__be32
398nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
399	    struct nlm_host *host, struct nlm_lock *lock, int wait,
400	    struct nlm_cookie *cookie, int reclaim)
401{
402	struct nlm_block	*block = NULL;
403	int			error;
404	__be32			ret;
405
406	dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
407				file_inode(file->f_file)->i_sb->s_id,
408				file_inode(file->f_file)->i_ino,
409				lock->fl.fl_type, lock->fl.fl_pid,
410				(long long)lock->fl.fl_start,
411				(long long)lock->fl.fl_end,
412				wait);
413
414	/* Lock file against concurrent access */
415	mutex_lock(&file->f_mutex);
416	/* Get existing block (in case client is busy-waiting)
417	 * or create new block
418	 */
419	block = nlmsvc_lookup_block(file, lock);
420	if (block == NULL) {
421		block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
422		ret = nlm_lck_denied_nolocks;
423		if (block == NULL)
424			goto out;
425		lock = &block->b_call->a_args.lock;
426	} else
427		lock->fl.fl_flags &= ~FL_SLEEP;
428
429	if (block->b_flags & B_QUEUED) {
430		dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
431							block, block->b_flags);
432		if (block->b_granted) {
433			nlmsvc_unlink_block(block);
434			ret = nlm_granted;
435			goto out;
436		}
437		if (block->b_flags & B_TIMED_OUT) {
438			nlmsvc_unlink_block(block);
439			ret = nlm_lck_denied;
440			goto out;
441		}
442		ret = nlm_drop_reply;
443		goto out;
444	}
445
446	if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
447		ret = nlm_lck_denied_grace_period;
448		goto out;
449	}
450	if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
451		ret = nlm_lck_denied_grace_period;
452		goto out;
453	}
454
455	if (!wait)
456		lock->fl.fl_flags &= ~FL_SLEEP;
457	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
458	lock->fl.fl_flags &= ~FL_SLEEP;
459
460	dprintk("lockd: vfs_lock_file returned %d\n", error);
461	switch (error) {
462		case 0:
463			ret = nlm_granted;
464			goto out;
465		case -EAGAIN:
466			/*
467			 * If this is a blocking request for an
468			 * already pending lock request then we need
469			 * to put it back on lockd's block list
470			 */
471			if (wait)
472				break;
473			ret = nlm_lck_denied;
474			goto out;
475		case FILE_LOCK_DEFERRED:
476			if (wait)
477				break;
478			/* Filesystem lock operation is in progress
479			   Add it to the queue waiting for callback */
480			ret = nlmsvc_defer_lock_rqst(rqstp, block);
481			goto out;
482		case -EDEADLK:
483			ret = nlm_deadlock;
484			goto out;
485		default:			/* includes ENOLCK */
486			ret = nlm_lck_denied_nolocks;
487			goto out;
488	}
489
490	ret = nlm_lck_blocked;
491
492	/* Append to list of blocked */
493	nlmsvc_insert_block(block, NLM_NEVER);
494out:
495	mutex_unlock(&file->f_mutex);
496	nlmsvc_release_block(block);
497	dprintk("lockd: nlmsvc_lock returned %u\n", ret);
498	return ret;
499}
500
501/*
502 * Test for presence of a conflicting lock.
503 */
504__be32
505nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
506		struct nlm_host *host, struct nlm_lock *lock,
507		struct nlm_lock *conflock, struct nlm_cookie *cookie)
508{
 
509	int			error;
510	__be32			ret;
511
512	dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
513				file_inode(file->f_file)->i_sb->s_id,
514				file_inode(file->f_file)->i_ino,
515				lock->fl.fl_type,
516				(long long)lock->fl.fl_start,
517				(long long)lock->fl.fl_end);
518
519	if (locks_in_grace(SVC_NET(rqstp))) {
520		ret = nlm_lck_denied_grace_period;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
521		goto out;
522	}
523
 
 
 
 
524	error = vfs_test_lock(file->f_file, &lock->fl);
 
 
 
 
525	if (error) {
526		/* We can't currently deal with deferred test requests */
527		if (error == FILE_LOCK_DEFERRED)
528			WARN_ON_ONCE(1);
529
530		ret = nlm_lck_denied_nolocks;
531		goto out;
532	}
533
534	if (lock->fl.fl_type == F_UNLCK) {
535		ret = nlm_granted;
536		goto out;
537	}
538
 
539	dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
540		lock->fl.fl_type, (long long)lock->fl.fl_start,
541		(long long)lock->fl.fl_end);
542	conflock->caller = "somehost";	/* FIXME */
543	conflock->len = strlen(conflock->caller);
544	conflock->oh.len = 0;		/* don't return OH info */
545	conflock->svid = lock->fl.fl_pid;
546	conflock->fl.fl_type = lock->fl.fl_type;
547	conflock->fl.fl_start = lock->fl.fl_start;
548	conflock->fl.fl_end = lock->fl.fl_end;
549	locks_release_private(&lock->fl);
550	ret = nlm_lck_denied;
551out:
 
 
552	return ret;
553}
554
555/*
556 * Remove a lock.
557 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
558 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
559 * afterwards. In this case the block will still be there, and hence
560 * must be removed.
561 */
562__be32
563nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
564{
565	int	error;
566
567	dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
568				file_inode(file->f_file)->i_sb->s_id,
569				file_inode(file->f_file)->i_ino,
570				lock->fl.fl_pid,
571				(long long)lock->fl.fl_start,
572				(long long)lock->fl.fl_end);
573
574	/* First, cancel any lock that might be there */
575	nlmsvc_cancel_blocked(net, file, lock);
576
577	lock->fl.fl_type = F_UNLCK;
578	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
579
580	return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
581}
582
583/*
584 * Cancel a previously blocked request.
585 *
586 * A cancel request always overrides any grant that may currently
587 * be in progress.
588 * The calling procedure must check whether the file can be closed.
589 */
590__be32
591nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
592{
593	struct nlm_block	*block;
594	int status = 0;
595
596	dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
597				file_inode(file->f_file)->i_sb->s_id,
598				file_inode(file->f_file)->i_ino,
599				lock->fl.fl_pid,
600				(long long)lock->fl.fl_start,
601				(long long)lock->fl.fl_end);
602
603	if (locks_in_grace(net))
604		return nlm_lck_denied_grace_period;
605
606	mutex_lock(&file->f_mutex);
607	block = nlmsvc_lookup_block(file, lock);
608	mutex_unlock(&file->f_mutex);
609	if (block != NULL) {
610		vfs_cancel_lock(block->b_file->f_file,
611				&block->b_call->a_args.lock.fl);
612		status = nlmsvc_unlink_block(block);
613		nlmsvc_release_block(block);
614	}
615	return status ? nlm_lck_denied : nlm_granted;
616}
617
618/*
619 * This is a callback from the filesystem for VFS file lock requests.
620 * It will be used if lm_grant is defined and the filesystem can not
621 * respond to the request immediately.
 
622 * For SETLK or SETLKW request it will get the local posix lock.
623 * In all cases it will move the block to the head of nlm_blocked q where
624 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
625 * deferred rpc for GETLK and SETLK.
626 */
627static void
628nlmsvc_update_deferred_block(struct nlm_block *block, int result)
 
629{
630	block->b_flags |= B_GOT_CALLBACK;
631	if (result == 0)
632		block->b_granted = 1;
633	else
634		block->b_flags |= B_TIMED_OUT;
 
 
 
 
635}
636
637static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
 
638{
639	struct nlm_block *block;
640	int rc = -ENOENT;
641
642	spin_lock(&nlm_blocked_lock);
643	list_for_each_entry(block, &nlm_blocked, b_list) {
644		if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
645			dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
646							block, block->b_flags);
647			if (block->b_flags & B_QUEUED) {
648				if (block->b_flags & B_TIMED_OUT) {
649					rc = -ENOLCK;
650					break;
651				}
652				nlmsvc_update_deferred_block(block, result);
653			} else if (result == 0)
654				block->b_granted = 1;
655
656			nlmsvc_insert_block_locked(block, 0);
657			svc_wake_up(block->b_daemon);
658			rc = 0;
659			break;
660		}
661	}
662	spin_unlock(&nlm_blocked_lock);
663	if (rc == -ENOENT)
664		printk(KERN_WARNING "lockd: grant for unknown block\n");
665	return rc;
666}
667
668/*
669 * Unblock a blocked lock request. This is a callback invoked from the
670 * VFS layer when a lock on which we blocked is removed.
671 *
672 * This function doesn't grant the blocked lock instantly, but rather moves
673 * the block to the head of nlm_blocked where it can be picked up by lockd.
674 */
675static void
676nlmsvc_notify_blocked(struct file_lock *fl)
677{
678	struct nlm_block	*block;
679
680	dprintk("lockd: VFS unblock notification for block %p\n", fl);
681	spin_lock(&nlm_blocked_lock);
682	list_for_each_entry(block, &nlm_blocked, b_list) {
683		if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
684			nlmsvc_insert_block_locked(block, 0);
685			spin_unlock(&nlm_blocked_lock);
686			svc_wake_up(block->b_daemon);
687			return;
688		}
689	}
690	spin_unlock(&nlm_blocked_lock);
691	printk(KERN_WARNING "lockd: notification for unknown block!\n");
692}
693
694static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
695{
696	return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
697}
698
699/*
700 * Since NLM uses two "keys" for tracking locks, we need to hash them down
701 * to one for the blocked_hash. Here, we're just xor'ing the host address
702 * with the pid in order to create a key value for picking a hash bucket.
703 */
704static unsigned long
705nlmsvc_owner_key(struct file_lock *fl)
706{
707	return (unsigned long)fl->fl_owner ^ (unsigned long)fl->fl_pid;
708}
709
710const struct lock_manager_operations nlmsvc_lock_operations = {
711	.lm_compare_owner = nlmsvc_same_owner,
712	.lm_owner_key = nlmsvc_owner_key,
713	.lm_notify = nlmsvc_notify_blocked,
714	.lm_grant = nlmsvc_grant_deferred,
715};
716
717/*
718 * Try to claim a lock that was previously blocked.
719 *
720 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
721 * RPC thread when notifying the client. This seems like overkill...
722 * Here's why:
723 *  -	we don't want to use a synchronous RPC thread, otherwise
724 *	we might find ourselves hanging on a dead portmapper.
725 *  -	Some lockd implementations (e.g. HP) don't react to
726 *	RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
727 */
728static void
729nlmsvc_grant_blocked(struct nlm_block *block)
730{
731	struct nlm_file		*file = block->b_file;
732	struct nlm_lock		*lock = &block->b_call->a_args.lock;
733	int			error;
734	loff_t			fl_start, fl_end;
735
736	dprintk("lockd: grant blocked lock %p\n", block);
737
738	kref_get(&block->b_count);
739
740	/* Unlink block request from list */
741	nlmsvc_unlink_block(block);
742
743	/* If b_granted is true this means we've been here before.
744	 * Just retry the grant callback, possibly refreshing the RPC
745	 * binding */
746	if (block->b_granted) {
747		nlm_rebind_host(block->b_host);
748		goto callback;
749	}
750
751	/* Try the lock operation again */
752	/* vfs_lock_file() can mangle fl_start and fl_end, but we need
753	 * them unchanged for the GRANT_MSG
754	 */
755	lock->fl.fl_flags |= FL_SLEEP;
756	fl_start = lock->fl.fl_start;
757	fl_end = lock->fl.fl_end;
758	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
759	lock->fl.fl_flags &= ~FL_SLEEP;
760	lock->fl.fl_start = fl_start;
761	lock->fl.fl_end = fl_end;
762
763	switch (error) {
764	case 0:
765		break;
766	case FILE_LOCK_DEFERRED:
767		dprintk("lockd: lock still blocked error %d\n", error);
768		nlmsvc_insert_block(block, NLM_NEVER);
769		nlmsvc_release_block(block);
770		return;
771	default:
772		printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
773				-error, __func__);
774		nlmsvc_insert_block(block, 10 * HZ);
775		nlmsvc_release_block(block);
776		return;
777	}
778
779callback:
780	/* Lock was granted by VFS. */
781	dprintk("lockd: GRANTing blocked lock.\n");
782	block->b_granted = 1;
783
784	/* keep block on the list, but don't reattempt until the RPC
785	 * completes or the submission fails
786	 */
787	nlmsvc_insert_block(block, NLM_NEVER);
788
789	/* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
790	 * will queue up a new one if this one times out
791	 */
792	error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
793				&nlmsvc_grant_ops);
794
795	/* RPC submission failed, wait a bit and retry */
796	if (error < 0)
797		nlmsvc_insert_block(block, 10 * HZ);
798}
799
800/*
801 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
802 * RPC call has succeeded or timed out.
803 * Like all RPC callbacks, it is invoked by the rpciod process, so it
804 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
805 * chain once more in order to have it removed by lockd itself (which can
806 * then sleep on the file semaphore without disrupting e.g. the nfs client).
807 */
808static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
809{
810	struct nlm_rqst		*call = data;
811	struct nlm_block	*block = call->a_block;
812	unsigned long		timeout;
813
814	dprintk("lockd: GRANT_MSG RPC callback\n");
815
816	spin_lock(&nlm_blocked_lock);
817	/* if the block is not on a list at this point then it has
818	 * been invalidated. Don't try to requeue it.
819	 *
820	 * FIXME: it's possible that the block is removed from the list
821	 * after this check but before the nlmsvc_insert_block. In that
822	 * case it will be added back. Perhaps we need better locking
823	 * for nlm_blocked?
824	 */
825	if (list_empty(&block->b_list))
826		goto out;
827
828	/* Technically, we should down the file semaphore here. Since we
829	 * move the block towards the head of the queue only, no harm
830	 * can be done, though. */
831	if (task->tk_status < 0) {
832		/* RPC error: Re-insert for retransmission */
833		timeout = 10 * HZ;
834	} else {
835		/* Call was successful, now wait for client callback */
836		timeout = 60 * HZ;
837	}
838	nlmsvc_insert_block_locked(block, timeout);
839	svc_wake_up(block->b_daemon);
840out:
841	spin_unlock(&nlm_blocked_lock);
842}
843
844/*
845 * FIXME: nlmsvc_release_block() grabs a mutex.  This is not allowed for an
846 * .rpc_release rpc_call_op
847 */
848static void nlmsvc_grant_release(void *data)
849{
850	struct nlm_rqst		*call = data;
851	nlmsvc_release_block(call->a_block);
852}
853
854static const struct rpc_call_ops nlmsvc_grant_ops = {
855	.rpc_call_done = nlmsvc_grant_callback,
856	.rpc_release = nlmsvc_grant_release,
857};
858
859/*
860 * We received a GRANT_RES callback. Try to find the corresponding
861 * block.
862 */
863void
864nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
865{
866	struct nlm_block	*block;
867
868	dprintk("grant_reply: looking for cookie %x, s=%d \n",
869		*(unsigned int *)(cookie->data), status);
870	if (!(block = nlmsvc_find_block(cookie)))
871		return;
872
873	if (block) {
874		if (status == nlm_lck_denied_grace_period) {
875			/* Try again in a couple of seconds */
876			nlmsvc_insert_block(block, 10 * HZ);
877		} else {
878			/* Lock is now held by client, or has been rejected.
879			 * In both cases, the block should be removed. */
880			nlmsvc_unlink_block(block);
881		}
882	}
883	nlmsvc_release_block(block);
884}
885
886/* Helper function to handle retry of a deferred block.
887 * If it is a blocking lock, call grant_blocked.
888 * For a non-blocking lock or test lock, revisit the request.
889 */
890static void
891retry_deferred_block(struct nlm_block *block)
892{
893	if (!(block->b_flags & B_GOT_CALLBACK))
894		block->b_flags |= B_TIMED_OUT;
895	nlmsvc_insert_block(block, NLM_TIMEOUT);
896	dprintk("revisit block %p flags %d\n",	block, block->b_flags);
897	if (block->b_deferred_req) {
898		block->b_deferred_req->revisit(block->b_deferred_req, 0);
899		block->b_deferred_req = NULL;
900	}
901}
902
903/*
904 * Retry all blocked locks that have been notified. This is where lockd
905 * picks up locks that can be granted, or grant notifications that must
906 * be retransmitted.
907 */
908unsigned long
909nlmsvc_retry_blocked(void)
910{
911	unsigned long	timeout = MAX_SCHEDULE_TIMEOUT;
912	struct nlm_block *block;
913
914	spin_lock(&nlm_blocked_lock);
915	while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
916		block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
917
918		if (block->b_when == NLM_NEVER)
919			break;
920		if (time_after(block->b_when, jiffies)) {
921			timeout = block->b_when - jiffies;
922			break;
923		}
924		spin_unlock(&nlm_blocked_lock);
925
926		dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
927			block, block->b_when);
928		if (block->b_flags & B_QUEUED) {
929			dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
930				block, block->b_granted, block->b_flags);
931			retry_deferred_block(block);
932		} else
933			nlmsvc_grant_blocked(block);
934		spin_lock(&nlm_blocked_lock);
935	}
936	spin_unlock(&nlm_blocked_lock);
937
938	return timeout;
939}