summaryrefslogtreecommitdiff
path: root/fs/dlm/device.c
blob: 99d8b6b07fbafcad3b0178c273060e1f127144ba (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
/******************************************************************************
*******************************************************************************
**
**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
**  Copyright (C) 2004-2005 Red Hat, Inc.  All rights reserved.
**
**  This copyrighted material is made available to anyone wishing to use,
**  modify, copy, or redistribute it subject to the terms and conditions
**  of the GNU General Public License v.2.
**
*******************************************************************************
******************************************************************************/

/*
 * device.c
 *
 * This is the userland interface to the DLM.
 *
 * The locking is done via a misc char device (find the
 * registered minor number in /proc/misc).
 *
 * User code should not use this interface directly but
 * call the library routines in libdlm.a instead.
 *
 */

#include <linux/miscdevice.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/module.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/signal.h>
#include <linux/spinlock.h>
#include <linux/idr.h>

#include <linux/dlm.h>
#include <linux/dlm_device.h>

#include "lvb_table.h"

static struct file_operations _dlm_fops;
static const char *name_prefix="dlm";
static struct list_head user_ls_list;
static struct mutex user_ls_lock;

/* Lock infos are stored in here indexed by lock ID */
static DEFINE_IDR(lockinfo_idr);
static rwlock_t lockinfo_lock;

/* Flags in li_flags */
#define LI_FLAG_COMPLETE   1
#define LI_FLAG_FIRSTLOCK  2
#define LI_FLAG_PERSISTENT 3
#define LI_FLAG_ONLIST     4

/* flags in ls_flags*/
#define LS_FLAG_DELETED   1
#define LS_FLAG_AUTOFREE  2


#define LOCKINFO_MAGIC 0x53595324

struct lock_info {
	uint32_t li_magic;
	uint8_t li_cmd;
	int8_t	li_grmode;
	int8_t  li_rqmode;
	struct dlm_lksb li_lksb;
	wait_queue_head_t li_waitq;
	unsigned long li_flags;
	void __user *li_castparam;
	void __user *li_castaddr;
	void __user *li_bastparam;
	void __user *li_bastaddr;
	void __user *li_pend_bastparam;
	void __user *li_pend_bastaddr;
	struct list_head li_ownerqueue;
	struct file_info *li_file;
	struct dlm_lksb __user *li_user_lksb;
	struct semaphore li_firstlock;
};

/* A queued AST no less */
struct ast_info {
	struct dlm_lock_result result;
	struct list_head list;
	uint32_t lvb_updated;
	uint32_t progress;      /* How much has been read */
};

/* One of these per userland lockspace */
struct user_ls {
	void    *ls_lockspace;
	atomic_t ls_refcnt;
	long     ls_flags;

	/* Passed into misc_register() */
	struct miscdevice ls_miscinfo;
	struct list_head  ls_list;
};

/* misc_device info for the control device */
static struct miscdevice ctl_device;

/*
 * Stuff we hang off the file struct.
 * The first two are to cope with unlocking all the
 * locks help by a process when it dies.
 */
struct file_info {
	struct list_head    fi_li_list;  /* List of active lock_infos */
	spinlock_t          fi_li_lock;
	struct list_head    fi_ast_list; /* Queue of ASTs to be delivered */
	spinlock_t          fi_ast_lock;
	wait_queue_head_t   fi_wait;
	struct user_ls     *fi_ls;
	atomic_t            fi_refcnt;   /* Number of users */
	unsigned long       fi_flags;    /* Bit 1 means the device is open */
};


/* get and put ops for file_info.
   Actually I don't really like "get" and "put", but everyone
   else seems to use them and I can't think of anything
   nicer at the moment */
static void get_file_info(struct file_info *f)
{
	atomic_inc(&f->fi_refcnt);
}

static void put_file_info(struct file_info *f)
{
	if (atomic_dec_and_test(&f->fi_refcnt))
		kfree(f);
}

static void release_lockinfo(struct lock_info *li)
{
	put_file_info(li->li_file);

	write_lock(&lockinfo_lock);
	idr_remove(&lockinfo_idr, li->li_lksb.sb_lkid);
	write_unlock(&lockinfo_lock);

	if (li->li_lksb.sb_lvbptr)
		kfree(li->li_lksb.sb_lvbptr);
	kfree(li);

	module_put(THIS_MODULE);
}

static struct lock_info *get_lockinfo(uint32_t lockid)
{
	struct lock_info *li;

	read_lock(&lockinfo_lock);
	li = idr_find(&lockinfo_idr, lockid);
	read_unlock(&lockinfo_lock);

	return li;
}

static int add_lockinfo(struct lock_info *li)
{
	int n;
	int r;
	int ret = -EINVAL;

	write_lock(&lockinfo_lock);

	if (idr_find(&lockinfo_idr, li->li_lksb.sb_lkid))
		goto out_up;

	ret = -ENOMEM;
	r = idr_pre_get(&lockinfo_idr, GFP_KERNEL);
	if (!r)
		goto out_up;

	r = idr_get_new_above(&lockinfo_idr, li, li->li_lksb.sb_lkid, &n);
	if (r)
		goto out_up;

	if (n != li->li_lksb.sb_lkid) {
		idr_remove(&lockinfo_idr, n);
		goto out_up;
	}

	ret = 0;

 out_up:
	write_unlock(&lockinfo_lock);

	return ret;
}


static struct user_ls *__find_lockspace(int minor)
{
	struct user_ls *lsinfo;

	list_for_each_entry(lsinfo, &user_ls_list, ls_list) {
		if (lsinfo->ls_miscinfo.minor == minor)
			return lsinfo;
	}
	return NULL;
}

/* Find a lockspace struct given the device minor number */
static struct user_ls *find_lockspace(int minor)
{
	struct user_ls *lsinfo;

	mutex_lock(&user_ls_lock);
	lsinfo = __find_lockspace(minor);
	mutex_unlock(&user_ls_lock);

	return lsinfo;
}

static void add_lockspace_to_list(struct user_ls *lsinfo)
{
	mutex_lock(&user_ls_lock);
	list_add(&lsinfo->ls_list, &user_ls_list);
	mutex_unlock(&user_ls_lock);
}

/* Register a lockspace with the DLM and create a misc
   device for userland to access it */
static int register_lockspace(char *name, struct user_ls **ls, int flags)
{
	struct user_ls *newls;
	int status;
	int namelen;

	namelen = strlen(name)+strlen(name_prefix)+2;

	newls = kzalloc(sizeof(struct user_ls), GFP_KERNEL);
	if (!newls)
		return -ENOMEM;

	newls->ls_miscinfo.name = kzalloc(namelen, GFP_KERNEL);
	if (!newls->ls_miscinfo.name) {
		kfree(newls);
		return -ENOMEM;
	}

	status = dlm_new_lockspace(name, strlen(name), &newls->ls_lockspace, 0,
				   DLM_USER_LVB_LEN);
	if (status != 0) {
		kfree(newls->ls_miscinfo.name);
		kfree(newls);
		return status;
	}

	snprintf((char*)newls->ls_miscinfo.name, namelen, "%s_%s",
		 name_prefix, name);

	newls->ls_miscinfo.fops = &_dlm_fops;
	newls->ls_miscinfo.minor = MISC_DYNAMIC_MINOR;

	status = misc_register(&newls->ls_miscinfo);
	if (status) {
		printk(KERN_ERR "dlm: misc register failed for %s\n", name);
		dlm_release_lockspace(newls->ls_lockspace, 0);
		kfree(newls->ls_miscinfo.name);
		kfree(newls);
		return status;
	}

	if (flags & DLM_USER_LSFLG_AUTOFREE)
		set_bit(LS_FLAG_AUTOFREE, &newls->ls_flags);

	add_lockspace_to_list(newls);
	*ls = newls;
	return 0;
}

/* Called with the user_ls_lock mutex held */
static int unregister_lockspace(struct user_ls *lsinfo, int force)
{
	int status;

	status = dlm_release_lockspace(lsinfo->ls_lockspace, force);
	if (status)
		return status;

	status = misc_deregister(&lsinfo->ls_miscinfo);
	if (status)
		return status;

	list_del(&lsinfo->ls_list);
	set_bit(LS_FLAG_DELETED, &lsinfo->ls_flags);
	lsinfo->ls_lockspace = NULL;
	if (atomic_read(&lsinfo->ls_refcnt) == 0) {
		kfree(lsinfo->ls_miscinfo.name);
		kfree(lsinfo);
	}

	return 0;
}

/* Add it to userland's AST queue */
static void add_to_astqueue(struct lock_info *li, void *astaddr, void *astparam,
			    int lvb_updated)
{
	struct ast_info *ast = kzalloc(sizeof(struct ast_info), GFP_KERNEL);
	if (!ast)
		return;

	ast->result.user_astparam = astparam;
	ast->result.user_astaddr  = astaddr;
	ast->result.user_lksb     = li->li_user_lksb;
	memcpy(&ast->result.lksb, &li->li_lksb, sizeof(struct dlm_lksb));
	ast->lvb_updated = lvb_updated;

	spin_lock(&li->li_file->fi_ast_lock);
	list_add_tail(&ast->list, &li->li_file->fi_ast_list);
	spin_unlock(&li->li_file->fi_ast_lock);
	wake_up_interruptible(&li->li_file->fi_wait);
}

static void bast_routine(void *param, int mode)
{
	struct lock_info *li = param;

	if (li && li->li_bastaddr)
		add_to_astqueue(li, li->li_bastaddr, li->li_bastparam, 0);
}

/*
 * This is the kernel's AST routine.
 * All lock, unlock & query operations complete here.
 * The only syncronous ops are those done during device close.
 */
static void ast_routine(void *param)
{
	struct lock_info *li = param;

	/* Param may be NULL if a persistent lock is unlocked by someone else */
	if (!li)
		return;

	/* If this is a succesful conversion then activate the blocking ast
	 * args from the conversion request */
	if (!test_bit(LI_FLAG_FIRSTLOCK, &li->li_flags) &&
	    li->li_lksb.sb_status == 0) {

		li->li_bastparam = li->li_pend_bastparam;
		li->li_bastaddr = li->li_pend_bastaddr;
		li->li_pend_bastaddr = NULL;
	}

	/* If it's an async request then post data to the user's AST queue. */
	if (li->li_castaddr) {
		int lvb_updated = 0;

		/* See if the lvb has been updated */
		if (dlm_lvb_operations[li->li_grmode+1][li->li_rqmode+1] == 1)
			lvb_updated = 1;

		if (li->li_lksb.sb_status == 0)
			li->li_grmode = li->li_rqmode;

		/* Only queue AST if the device is still open */
		if (test_bit(1, &li->li_file->fi_flags))
			add_to_astqueue(li, li->li_castaddr, li->li_castparam,
					lvb_updated);

		/* If it's a new lock operation that failed, then
		 * remove it from the owner queue and free the
		 * lock_info.
		 */
		if (test_and_clear_bit(LI_FLAG_FIRSTLOCK, &li->li_flags) &&
		    li->li_lksb.sb_status != 0) {

			/* Wait till dlm_lock() has finished */
			down(&li->li_firstlock);
			up(&li->li_firstlock);

			spin_lock(&li->li_file->fi_li_lock);
			list_del(&li->li_ownerqueue);
			clear_bit(LI_FLAG_ONLIST, &li->li_flags);
			spin_unlock(&li->li_file->fi_li_lock);
			release_lockinfo(li);
			return;
		}
		/* Free unlocks & queries */
		if (li->li_lksb.sb_status == -DLM_EUNLOCK ||
		    li->li_cmd == DLM_USER_QUERY) {
			release_lockinfo(li);
		}
	} else {
		/* Synchronous request, just wake up the caller */
		set_bit(LI_FLAG_COMPLETE, &li->li_flags);
		wake_up_interruptible(&li->li_waitq);
	}
}

/*
 * Wait for the lock op to complete and return the status.
 */
static int wait_for_ast(struct lock_info *li)
{
	/* Wait for the AST routine to complete */
	set_task_state(current, TASK_INTERRUPTIBLE);
	while (!test_bit(LI_FLAG_COMPLETE, &li->li_flags))
		schedule();

	set_task_state(current, TASK_RUNNING);

	return li->li_lksb.sb_status;
}


/* Open on control device */
static int dlm_ctl_open(struct inode *inode, struct file *file)
{
	file->private_data = NULL;
	return 0;
}

/* Close on control device */
static int dlm_ctl_close(struct inode *inode, struct file *file)
{
	return 0;
}

/* Open on lockspace device */
static int dlm_open(struct inode *inode, struct file *file)
{
	struct file_info *f;
	struct user_ls *lsinfo;

	lsinfo = find_lockspace(iminor(inode));
	if (!lsinfo)
		return -ENOENT;

	f = kzalloc(sizeof(struct file_info), GFP_KERNEL);
	if (!f)
		return -ENOMEM;

	atomic_inc(&lsinfo->ls_refcnt);
	INIT_LIST_HEAD(&f->fi_li_list);
	INIT_LIST_HEAD(&f->fi_ast_list);
	spin_lock_init(&f->fi_li_lock);
	spin_lock_init(&f->fi_ast_lock);
	init_waitqueue_head(&f->fi_wait);
	f->fi_ls = lsinfo;
	f->fi_flags = 0;
	get_file_info(f);
	set_bit(1, &f->fi_flags);

	file->private_data = f;

	return 0;
}

/* Check the user's version matches ours */
static int check_version(struct dlm_write_request *req)
{
	if (req->version[0] != DLM_DEVICE_VERSION_MAJOR ||
	    (req->version[0] == DLM_DEVICE_VERSION_MAJOR &&
	     req->version[1] > DLM_DEVICE_VERSION_MINOR)) {

		printk(KERN_DEBUG "dlm: process %s (%d) version mismatch "
		       "user (%d.%d.%d) kernel (%d.%d.%d)\n",
		       current->comm,
		       current->pid,
		       req->version[0],
		       req->version[1],
		       req->version[2],
		       DLM_DEVICE_VERSION_MAJOR,
		       DLM_DEVICE_VERSION_MINOR,
		       DLM_DEVICE_VERSION_PATCH);
		return -EINVAL;
	}
	return 0;
}

/* Close on lockspace device */
static int dlm_close(struct inode *inode, struct file *file)
{
	struct file_info *f = file->private_data;
	struct lock_info li;
	struct lock_info *old_li, *safe;
	sigset_t tmpsig;
	sigset_t allsigs;
	struct user_ls *lsinfo;
	DECLARE_WAITQUEUE(wq, current);

	lsinfo = find_lockspace(iminor(inode));
	if (!lsinfo)
		return -ENOENT;

	/* Mark this closed so that ASTs will not be delivered any more */
	clear_bit(1, &f->fi_flags);

	/* Block signals while we are doing this */
	sigfillset(&allsigs);
	sigprocmask(SIG_BLOCK, &allsigs, &tmpsig);

	/* We use our own lock_info struct here, so that any
	 * outstanding "real" ASTs will be delivered with the
	 * corresponding "real" params, thus freeing the lock_info
	 * that belongs the lock. This catches the corner case where
	 * a lock is BUSY when we try to unlock it here
	 */
	memset(&li, 0, sizeof(li));
	clear_bit(LI_FLAG_COMPLETE, &li.li_flags);
	init_waitqueue_head(&li.li_waitq);
	add_wait_queue(&li.li_waitq, &wq);

	/*
	 * Free any outstanding locks, they are on the
	 * list in LIFO order so there should be no problems
	 * about unlocking parents before children.
	 */
	list_for_each_entry_safe(old_li, safe, &f->fi_li_list, li_ownerqueue) {
		int status;
		int flags = 0;

		/* Don't unlock persistent locks, just mark them orphaned */
		if (test_bit(LI_FLAG_PERSISTENT, &old_li->li_flags)) {
			list_del(&old_li->li_ownerqueue);

			/* Update master copy */
			/* TODO: Check locking core updates the local and
			   remote ORPHAN flags */
			li.li_lksb.sb_lkid = old_li->li_lksb.sb_lkid;
			status = dlm_lock(f->fi_ls->ls_lockspace,
					  old_li->li_grmode, &li.li_lksb,
					  DLM_LKF_CONVERT|DLM_LKF_ORPHAN,
					  NULL, 0, 0, ast_routine, NULL, NULL);
			if (status != 0)
				printk("dlm: Error orphaning lock %x: %d\n",
				       old_li->li_lksb.sb_lkid, status);

			/* But tidy our references in it */
			release_lockinfo(old_li);
			continue;
		}

		clear_bit(LI_FLAG_COMPLETE, &li.li_flags);

		flags = DLM_LKF_FORCEUNLOCK;
		if (old_li->li_grmode >= DLM_LOCK_PW)
			flags |= DLM_LKF_IVVALBLK;

		status = dlm_unlock(f->fi_ls->ls_lockspace,
				    old_li->li_lksb.sb_lkid, flags,
				    &li.li_lksb, &li);

		/* Must wait for it to complete as the next lock could be its
		 * parent */
		if (status == 0)
			wait_for_ast(&li);

		/* Unlock suceeded, free the lock_info struct. */
		if (status == 0)
			release_lockinfo(old_li);
	}

	remove_wait_queue(&li.li_waitq, &wq);

	/*
	 * If this is the last reference to the lockspace
	 * then free the struct. If it's an AUTOFREE lockspace
	 * then free the whole thing.
	 */
	mutex_lock(&user_ls_lock);
	if (atomic_dec_and_test(&lsinfo->ls_refcnt)) {

		if (lsinfo->ls_lockspace) {
			if (test_bit(LS_FLAG_AUTOFREE, &lsinfo->ls_flags)) {
				unregister_lockspace(lsinfo, 1);
			}
		} else {
			kfree(lsinfo->ls_miscinfo.name);
			kfree(lsinfo);
		}
	}
	mutex_unlock(&user_ls_lock);
	put_file_info(f);

	/* Restore signals */
	sigprocmask(SIG_SETMASK, &tmpsig, NULL);
	recalc_sigpending();

	return 0;
}

static int do_user_create_lockspace(struct file_info *fi, uint8_t cmd,
				    struct dlm_lspace_params *kparams)
{
	int status;
	struct user_ls *lsinfo;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	status = register_lockspace(kparams->name, &lsinfo, kparams->flags);

	/* If it succeeded then return the minor number */
	if (status == 0)
		status = lsinfo->ls_miscinfo.minor;

	return status;
}

static int do_user_remove_lockspace(struct file_info *fi, uint8_t cmd,
				    struct dlm_lspace_params *kparams)
{
	int status;
	int force = 1;
	struct user_ls *lsinfo;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	mutex_lock(&user_ls_lock);
	lsinfo = __find_lockspace(kparams->minor);
	if (!lsinfo) {
		mutex_unlock(&user_ls_lock);
		return -EINVAL;
	}

	if (kparams->flags & DLM_USER_LSFLG_FORCEFREE)
		force = 2;

	status = unregister_lockspace(lsinfo, force);
	mutex_unlock(&user_ls_lock);

	return status;
}

/* Read call, might block if no ASTs are waiting.
 * It will only ever return one message at a time, regardless
 * of how many are pending.
 */
static ssize_t dlm_read(struct file *file, char __user *buffer, size_t count,
			loff_t *ppos)
{
	struct file_info *fi = file->private_data;
	struct ast_info *ast;
	int data_size;
	int offset;
	DECLARE_WAITQUEUE(wait, current);

	if (count < sizeof(struct dlm_lock_result))
		return -EINVAL;

	spin_lock(&fi->fi_ast_lock);
	if (list_empty(&fi->fi_ast_list)) {

		/* No waiting ASTs.
		 * Return EOF if the lockspace been deleted.
		 */
		if (test_bit(LS_FLAG_DELETED, &fi->fi_ls->ls_flags))
			return 0;

		if (file->f_flags & O_NONBLOCK) {
			spin_unlock(&fi->fi_ast_lock);
			return -EAGAIN;
		}

		add_wait_queue(&fi->fi_wait, &wait);

	repeat:
		set_current_state(TASK_INTERRUPTIBLE);
		if (list_empty(&fi->fi_ast_list) &&
		    !signal_pending(current)) {

			spin_unlock(&fi->fi_ast_lock);
			schedule();
			spin_lock(&fi->fi_ast_lock);
			goto repeat;
		}

		current->state = TASK_RUNNING;
		remove_wait_queue(&fi->fi_wait, &wait);

		if (signal_pending(current)) {
			spin_unlock(&fi->fi_ast_lock);
			return -ERESTARTSYS;
		}
	}

	ast = list_entry(fi->fi_ast_list.next, struct ast_info, list);
	list_del(&ast->list);
	spin_unlock(&fi->fi_ast_lock);

	/* Work out the size of the returned data */
	data_size = sizeof(struct dlm_lock_result);
	if (ast->lvb_updated && ast->result.lksb.sb_lvbptr)
		data_size += DLM_USER_LVB_LEN;

	offset = sizeof(struct dlm_lock_result);

	/* Room for the extended data ? */
	if (count >= data_size) {

		if (ast->lvb_updated && ast->result.lksb.sb_lvbptr) {
			if (copy_to_user(buffer+offset,
					 ast->result.lksb.sb_lvbptr,
					 DLM_USER_LVB_LEN))
				return -EFAULT;
			ast->result.lvb_offset = offset;
			offset += DLM_USER_LVB_LEN;
		}
	}

	ast->result.length = data_size;
	/* Copy the header now it has all the offsets in it */
	if (copy_to_user(buffer, &ast->result, sizeof(struct dlm_lock_result)))
		offset = -EFAULT;

	/* If we only returned a header and there's more to come then put it
	   back on the list */
	if (count < data_size) {
		spin_lock(&fi->fi_ast_lock);
		list_add(&ast->list, &fi->fi_ast_list);
		spin_unlock(&fi->fi_ast_lock);
	} else
		kfree(ast);
	return offset;
}

static unsigned int dlm_poll(struct file *file, poll_table *wait)
{
	struct file_info *fi = file->private_data;

	poll_wait(file, &fi->fi_wait, wait);

	spin_lock(&fi->fi_ast_lock);
	if (!list_empty(&fi->fi_ast_list)) {
		spin_unlock(&fi->fi_ast_lock);
		return POLLIN | POLLRDNORM;
	}

	spin_unlock(&fi->fi_ast_lock);
	return 0;
}

static struct lock_info *allocate_lockinfo(struct file_info *fi, uint8_t cmd,
					   struct dlm_lock_params *kparams)
{
	struct lock_info *li;

	if (!try_module_get(THIS_MODULE))
		return NULL;

	li = kzalloc(sizeof(struct lock_info), GFP_KERNEL);
	if (li) {
		li->li_magic     = LOCKINFO_MAGIC;
		li->li_file      = fi;
		li->li_cmd       = cmd;
		li->li_flags     = 0;
		li->li_grmode    = -1;
		li->li_rqmode    = -1;
		li->li_pend_bastparam = NULL;
		li->li_pend_bastaddr  = NULL;
		li->li_castaddr   = NULL;
		li->li_castparam  = NULL;
		li->li_lksb.sb_lvbptr = NULL;
		li->li_bastaddr  = kparams->bastaddr;
		li->li_bastparam = kparams->bastparam;

		get_file_info(fi);
	}
	return li;
}

static int do_user_lock(struct file_info *fi, uint8_t cmd,
			struct dlm_lock_params *kparams)
{
	struct lock_info *li;
	int status;

	/*
	 * Validate things that we need to have correct.
	 */
	if (!kparams->castaddr)
		return -EINVAL;

	if (!kparams->lksb)
		return -EINVAL;

	/* Persistent child locks are not available yet */
	if ((kparams->flags & DLM_LKF_PERSISTENT) && kparams->parent)
		return -EINVAL;

        /* For conversions, there should already be a lockinfo struct,
	   unless we are adopting an orphaned persistent lock */
	if (kparams->flags & DLM_LKF_CONVERT) {

		li = get_lockinfo(kparams->lkid);

		/* If this is a persistent lock we will have to create a
		   lockinfo again */
		if (!li && (kparams->flags & DLM_LKF_PERSISTENT)) {
			li = allocate_lockinfo(fi, cmd, kparams);
			if (!li)
				return -ENOMEM;

			li->li_lksb.sb_lkid = kparams->lkid;
			li->li_castaddr  = kparams->castaddr;
			li->li_castparam = kparams->castparam;

			/* OK, this isn;t exactly a FIRSTLOCK but it is the
			   first time we've used this lockinfo, and if things
			   fail we want rid of it */
			init_MUTEX_LOCKED(&li->li_firstlock);
			set_bit(LI_FLAG_FIRSTLOCK, &li->li_flags);
			add_lockinfo(li);

			/* TODO: do a query to get the current state ?? */
		}
		if (!li)
			return -EINVAL;

		if (li->li_magic != LOCKINFO_MAGIC)
			return -EINVAL;

		/* For conversions don't overwrite the current blocking AST
		   info so that:
		   a) if a blocking AST fires before the conversion is queued
		      it runs the current handler
		   b) if the conversion is cancelled, the original blocking AST
		      declaration is active
		   The pend_ info is made active when the conversion
		   completes.
		*/
		li->li_pend_bastaddr  = kparams->bastaddr;
		li->li_pend_bastparam = kparams->bastparam;
	} else {
		li = allocate_lockinfo(fi, cmd, kparams);
		if (!li)
			return -ENOMEM;

		/* semaphore to allow us to complete our work before
  		   the AST routine runs. In fact we only need (and use) this
		   when the initial lock fails */
		init_MUTEX_LOCKED(&li->li_firstlock);
		set_bit(LI_FLAG_FIRSTLOCK, &li->li_flags);
	}

	li->li_user_lksb = kparams->lksb;
	li->li_castaddr  = kparams->castaddr;
	li->li_castparam = kparams->castparam;
	li->li_lksb.sb_lkid = kparams->lkid;
	li->li_rqmode    = kparams->mode;
	if (kparams->flags & DLM_LKF_PERSISTENT)
		set_bit(LI_FLAG_PERSISTENT, &li->li_flags);

	/* Copy in the value block */
	if (kparams->flags & DLM_LKF_VALBLK) {
		if (!li->li_lksb.sb_lvbptr) {
			li->li_lksb.sb_lvbptr = kmalloc(DLM_USER_LVB_LEN,
							GFP_KERNEL);
			if (!li->li_lksb.sb_lvbptr) {
				status = -ENOMEM;
				goto out_err;
			}
		}

		memcpy(li->li_lksb.sb_lvbptr, kparams->lvb, DLM_USER_LVB_LEN);
	}

	/* Lock it ... */
	status = dlm_lock(fi->fi_ls->ls_lockspace,
			  kparams->mode, &li->li_lksb,
			  kparams->flags,
			  kparams->name, kparams->namelen,
			  kparams->parent,
			  ast_routine,
			  li,
			  (li->li_pend_bastaddr || li->li_bastaddr) ?
			   bast_routine : NULL);
	if (status)
		goto out_err;

	/* If it succeeded (this far) with a new lock then keep track of
	   it on the file's lockinfo list */
	if (!status && test_bit(LI_FLAG_FIRSTLOCK, &li->li_flags)) {

		spin_lock(&fi->fi_li_lock);
		list_add(&li->li_ownerqueue, &fi->fi_li_list);
		set_bit(LI_FLAG_ONLIST, &li->li_flags);
		spin_unlock(&fi->fi_li_lock);
		if (add_lockinfo(li))
			printk(KERN_WARNING "Add lockinfo failed\n");

		up(&li->li_firstlock);
	}

	/* Return the lockid as the user needs it /now/ */
	return li->li_lksb.sb_lkid;

 out_err:
	if (test_bit(LI_FLAG_FIRSTLOCK, &li->li_flags))
		release_lockinfo(li);
	return status;

}

static int do_user_unlock(struct file_info *fi, uint8_t cmd,
			  struct dlm_lock_params *kparams)
{
	struct lock_info *li;
	int status;
	int convert_cancel = 0;

	li = get_lockinfo(kparams->lkid);
	if (!li) {
		li = allocate_lockinfo(fi, cmd, kparams);
		if (!li)
			return -ENOMEM;
		spin_lock(&fi->fi_li_lock);
		list_add(&li->li_ownerqueue, &fi->fi_li_list);
		set_bit(LI_FLAG_ONLIST, &li->li_flags);
		spin_unlock(&fi->fi_li_lock);
	}

	if (li->li_magic != LOCKINFO_MAGIC)
		return -EINVAL;

	li->li_user_lksb = kparams->lksb;
	li->li_castparam = kparams->castparam;
	li->li_cmd       = cmd;

	/* Cancelling a conversion doesn't remove the lock...*/
	if (kparams->flags & DLM_LKF_CANCEL && li->li_grmode != -1)
		convert_cancel = 1;

	/* Wait until dlm_lock() has completed */
	if (!test_bit(LI_FLAG_ONLIST, &li->li_flags)) {
		down(&li->li_firstlock);
		up(&li->li_firstlock);
	}

	/* dlm_unlock() passes a 0 for castaddr which means don't overwrite
	   the existing li_castaddr as that's the completion routine for
	   unlocks. dlm_unlock_wait() specifies a new AST routine to be
	   executed when the unlock completes. */
	if (kparams->castaddr)
		li->li_castaddr = kparams->castaddr;

	/* Use existing lksb & astparams */
	status = dlm_unlock(fi->fi_ls->ls_lockspace,
			     kparams->lkid,
			     kparams->flags, &li->li_lksb, li);

	if (!status && !convert_cancel) {
		spin_lock(&fi->fi_li_lock);
		list_del(&li->li_ownerqueue);
		clear_bit(LI_FLAG_ONLIST, &li->li_flags);
		spin_unlock(&fi->fi_li_lock);
	}

	return status;
}

/* Write call, submit a locking request */
static ssize_t dlm_write(struct file *file, const char __user *buffer,
			 size_t count, loff_t *ppos)
{
	struct file_info *fi = file->private_data;
	struct dlm_write_request *kparams;
	sigset_t tmpsig;
	sigset_t allsigs;
	int status;

	/* -1 because lock name is optional */
	if (count < sizeof(struct dlm_write_request)-1)
		return -EINVAL;

	/* Has the lockspace been deleted */
	if (fi && test_bit(LS_FLAG_DELETED, &fi->fi_ls->ls_flags))
		return -ENOENT;

	kparams = kmalloc(count, GFP_KERNEL);
	if (!kparams)
		return -ENOMEM;

	status = -EFAULT;
	/* Get the command info */
	if (copy_from_user(kparams, buffer, count))
		goto out_free;

	status = -EBADE;
	if (check_version(kparams))
		goto out_free;

	/* Block signals while we are doing this */
	sigfillset(&allsigs);
	sigprocmask(SIG_BLOCK, &allsigs, &tmpsig);

	status = -EINVAL;
	switch (kparams->cmd)
	{
	case DLM_USER_LOCK:
		if (!fi) goto out_sig;
		status = do_user_lock(fi, kparams->cmd, &kparams->i.lock);
		break;

	case DLM_USER_UNLOCK:
		if (!fi) goto out_sig;
		status = do_user_unlock(fi, kparams->cmd, &kparams->i.lock);
		break;

	case DLM_USER_CREATE_LOCKSPACE:
		if (fi) goto out_sig;
		status = do_user_create_lockspace(fi, kparams->cmd,
						  &kparams->i.lspace);
		break;

	case DLM_USER_REMOVE_LOCKSPACE:
		if (fi) goto out_sig;
		status = do_user_remove_lockspace(fi, kparams->cmd,
						  &kparams->i.lspace);
		break;
	default:
		printk("Unknown command passed to DLM device : %d\n",
			kparams->cmd);
		break;
	}

 out_sig:
	/* Restore signals */
	sigprocmask(SIG_SETMASK, &tmpsig, NULL);
	recalc_sigpending();

 out_free:
	kfree(kparams);
	if (status == 0)
		return count;
	else
		return status;
}

static struct file_operations _dlm_fops = {
      .open    = dlm_open,
      .release = dlm_close,
      .read    = dlm_read,
      .write   = dlm_write,
      .poll    = dlm_poll,
      .owner   = THIS_MODULE,
};

static struct file_operations _dlm_ctl_fops = {
      .open    = dlm_ctl_open,
      .release = dlm_ctl_close,
      .write   = dlm_write,
      .owner   = THIS_MODULE,
};

/*
 * Create control device
 */
static int __init dlm_device_init(void)
{
	int r;

	INIT_LIST_HEAD(&user_ls_list);
	mutex_init(&user_ls_lock);
	rwlock_init(&lockinfo_lock);

	ctl_device.name = "dlm-control";
	ctl_device.fops = &_dlm_ctl_fops;
	ctl_device.minor = MISC_DYNAMIC_MINOR;

	r = misc_register(&ctl_device);
	if (r) {
		printk(KERN_ERR "dlm: misc_register failed for control dev\n");
		return r;
	}

	return 0;
}

static void __exit dlm_device_exit(void)
{
	misc_deregister(&ctl_device);
}

MODULE_DESCRIPTION("Distributed Lock Manager device interface");
MODULE_AUTHOR("Red Hat, Inc.");
MODULE_LICENSE("GPL");

module_init(dlm_device_init);
module_exit(dlm_device_exit);