-
Notifications
You must be signed in to change notification settings - Fork 260
/
vfs_vnode.c
2115 lines (1850 loc) · 53.4 KB
/
vfs_vnode.c
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
/* $NetBSD: vfs_vnode.c,v 1.149 2023/02/24 11:02:27 riastradh Exp $ */
/*-
* Copyright (c) 1997-2011, 2019, 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
* NASA Ames Research Center, by Charles M. Hannum, and by Andrew Doran.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)vfs_subr.c 8.13 (Berkeley) 4/18/94
*/
/*
* The vnode cache subsystem.
*
* Life-cycle
*
* Normally, there are two points where new vnodes are created:
* VOP_CREATE(9) and VOP_LOOKUP(9). The life-cycle of a vnode
* starts in one of the following ways:
*
* - Allocation, via vcache_get(9) or vcache_new(9).
* - Reclamation of inactive vnode, via vcache_vget(9).
*
* Recycle from a free list, via getnewvnode(9) -> getcleanvnode(9)
* was another, traditional way. Currently, only the draining thread
* recycles the vnodes. This behaviour might be revisited.
*
* The life-cycle ends when the last reference is dropped, usually
* in VOP_REMOVE(9). In such case, VOP_INACTIVE(9) is called to inform
* the file system that vnode is inactive. Via this call, file system
* indicates whether vnode can be recycled (usually, it checks its own
* references, e.g. count of links, whether the file was removed).
*
* Depending on indication, vnode can be put into a free list (cache),
* or cleaned via vcache_reclaim, which calls VOP_RECLAIM(9) to
* disassociate underlying file system from the vnode, and finally
* destroyed.
*
* Vnode state
*
* Vnode is always in one of six states:
* - MARKER This is a marker vnode to help list traversal. It
* will never change its state.
* - LOADING Vnode is associating underlying file system and not
* yet ready to use.
* - LOADED Vnode has associated underlying file system and is
* ready to use.
* - BLOCKED Vnode is active but cannot get new references.
* - RECLAIMING Vnode is disassociating from the underlying file
* system.
* - RECLAIMED Vnode has disassociated from underlying file system
* and is dead.
*
* Valid state changes are:
* LOADING -> LOADED
* Vnode has been initialised in vcache_get() or
* vcache_new() and is ready to use.
* BLOCKED -> RECLAIMING
* Vnode starts disassociation from underlying file
* system in vcache_reclaim().
* RECLAIMING -> RECLAIMED
* Vnode finished disassociation from underlying file
* system in vcache_reclaim().
* LOADED -> BLOCKED
* Either vcache_rekey*() is changing the vnode key or
* vrelel() is about to call VOP_INACTIVE().
* BLOCKED -> LOADED
* The block condition is over.
* LOADING -> RECLAIMED
* Either vcache_get() or vcache_new() failed to
* associate the underlying file system or vcache_rekey*()
* drops a vnode used as placeholder.
*
* Of these states LOADING, BLOCKED and RECLAIMING are intermediate
* and it is possible to wait for state change.
*
* State is protected with v_interlock with one exception:
* to change from LOADING both v_interlock and vcache_lock must be held
* so it is possible to check "state == LOADING" without holding
* v_interlock. See vcache_get() for details.
*
* Reference counting
*
* Vnode is considered active, if reference count (vnode_t::v_usecount)
* is non-zero. It is maintained using: vref(9) and vrele(9), as well
* as vput(9), routines. Common points holding references are e.g.
* file openings, current working directory, mount points, etc.
*
* v_usecount is adjusted with atomic operations, however to change
* from a non-zero value to zero the interlock must also be held.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.149 2023/02/24 11:02:27 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_pax.h"
#endif
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/atomic.h>
#include <sys/buf.h>
#include <sys/conf.h>
#include <sys/device.h>
#include <sys/hash.h>
#include <sys/kauth.h>
#include <sys/kmem.h>
#include <sys/kthread.h>
#include <sys/module.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/pax.h>
#include <sys/syscallargs.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/vnode_impl.h>
#include <sys/wapbl.h>
#include <sys/fstrans.h>
#include <miscfs/deadfs/deadfs.h>
#include <miscfs/specfs/specdev.h>
#include <uvm/uvm.h>
#include <uvm/uvm_readahead.h>
#include <uvm/uvm_stat.h>
/* Flags to vrelel. */
#define VRELEL_ASYNC 0x0001 /* Always defer to vrele thread. */
#define LRU_VRELE 0
#define LRU_FREE 1
#define LRU_HOLD 2
#define LRU_COUNT 3
/*
* There are three lru lists: one holds vnodes waiting for async release,
* one is for vnodes which have no buffer/page references and one for those
* which do (i.e. v_holdcnt is non-zero). We put the lists into a single,
* private cache line as vnodes migrate between them while under the same
* lock (vdrain_lock).
*/
u_int numvnodes __cacheline_aligned;
static vnodelst_t lru_list[LRU_COUNT] __cacheline_aligned;
static kmutex_t vdrain_lock __cacheline_aligned;
static kcondvar_t vdrain_cv;
static int vdrain_gen;
static kcondvar_t vdrain_gen_cv;
static bool vdrain_retry;
static lwp_t * vdrain_lwp;
SLIST_HEAD(hashhead, vnode_impl);
static kmutex_t vcache_lock __cacheline_aligned;
static kcondvar_t vcache_cv;
static u_int vcache_hashsize;
static u_long vcache_hashmask;
static struct hashhead *vcache_hashtab;
static pool_cache_t vcache_pool;
static void lru_requeue(vnode_t *, vnodelst_t *);
static vnodelst_t * lru_which(vnode_t *);
static vnode_impl_t * vcache_alloc(void);
static void vcache_dealloc(vnode_impl_t *);
static void vcache_free(vnode_impl_t *);
static void vcache_init(void);
static void vcache_reinit(void);
static void vcache_reclaim(vnode_t *);
static void vrelel(vnode_t *, int, int);
static void vdrain_thread(void *);
static void vnpanic(vnode_t *, const char *, ...)
__printflike(2, 3);
/* Routines having to do with the management of the vnode table. */
/*
* The high bit of v_usecount is a gate for vcache_tryvget(). It's set
* only when the vnode state is LOADED.
* The next bit of v_usecount is a flag for vrelel(). It's set
* from vcache_vget() and vcache_tryvget() whenever the operation succeeds.
*/
#define VUSECOUNT_MASK 0x3fffffff
#define VUSECOUNT_GATE 0x80000000
#define VUSECOUNT_VGET 0x40000000
/*
* Return the current usecount of a vnode.
*/
inline int
vrefcnt(struct vnode *vp)
{
return atomic_load_relaxed(&vp->v_usecount) & VUSECOUNT_MASK;
}
/* Vnode state operations and diagnostics. */
#if defined(DIAGNOSTIC)
#define VSTATE_VALID(state) \
((state) != VS_ACTIVE && (state) != VS_MARKER)
#define VSTATE_GET(vp) \
vstate_assert_get((vp), __func__, __LINE__)
#define VSTATE_CHANGE(vp, from, to) \
vstate_assert_change((vp), (from), (to), __func__, __LINE__)
#define VSTATE_WAIT_STABLE(vp) \
vstate_assert_wait_stable((vp), __func__, __LINE__)
void
_vstate_assert(vnode_t *vp, enum vnode_state state, const char *func, int line,
bool has_lock)
{
vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
int refcnt = vrefcnt(vp);
if (!has_lock) {
enum vnode_state vstate = atomic_load_relaxed(&vip->vi_state);
if (state == VS_ACTIVE && refcnt > 0 &&
(vstate == VS_LOADED || vstate == VS_BLOCKED))
return;
if (vstate == state)
return;
mutex_enter((vp)->v_interlock);
}
KASSERTMSG(mutex_owned(vp->v_interlock), "at %s:%d", func, line);
if ((state == VS_ACTIVE && refcnt > 0 &&
(vip->vi_state == VS_LOADED || vip->vi_state == VS_BLOCKED)) ||
vip->vi_state == state) {
if (!has_lock)
mutex_exit((vp)->v_interlock);
return;
}
vnpanic(vp, "state is %s, usecount %d, expected %s at %s:%d",
vstate_name(vip->vi_state), refcnt,
vstate_name(state), func, line);
}
static enum vnode_state
vstate_assert_get(vnode_t *vp, const char *func, int line)
{
vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
KASSERTMSG(mutex_owned(vp->v_interlock), "at %s:%d", func, line);
if (! VSTATE_VALID(vip->vi_state))
vnpanic(vp, "state is %s at %s:%d",
vstate_name(vip->vi_state), func, line);
return vip->vi_state;
}
static void
vstate_assert_wait_stable(vnode_t *vp, const char *func, int line)
{
vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
KASSERTMSG(mutex_owned(vp->v_interlock), "at %s:%d", func, line);
if (! VSTATE_VALID(vip->vi_state))
vnpanic(vp, "state is %s at %s:%d",
vstate_name(vip->vi_state), func, line);
while (vip->vi_state != VS_LOADED && vip->vi_state != VS_RECLAIMED)
cv_wait(&vp->v_cv, vp->v_interlock);
if (! VSTATE_VALID(vip->vi_state))
vnpanic(vp, "state is %s at %s:%d",
vstate_name(vip->vi_state), func, line);
}
static void
vstate_assert_change(vnode_t *vp, enum vnode_state from, enum vnode_state to,
const char *func, int line)
{
bool gated = (atomic_load_relaxed(&vp->v_usecount) & VUSECOUNT_GATE);
vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
KASSERTMSG(mutex_owned(vp->v_interlock), "at %s:%d", func, line);
if (from == VS_LOADING)
KASSERTMSG(mutex_owned(&vcache_lock), "at %s:%d", func, line);
if (! VSTATE_VALID(from))
vnpanic(vp, "from is %s at %s:%d",
vstate_name(from), func, line);
if (! VSTATE_VALID(to))
vnpanic(vp, "to is %s at %s:%d",
vstate_name(to), func, line);
if (vip->vi_state != from)
vnpanic(vp, "from is %s, expected %s at %s:%d\n",
vstate_name(vip->vi_state), vstate_name(from), func, line);
if ((from == VS_LOADED) != gated)
vnpanic(vp, "state is %s, gate %d does not match at %s:%d\n",
vstate_name(vip->vi_state), gated, func, line);
/* Open/close the gate for vcache_tryvget(). */
if (to == VS_LOADED) {
membar_release();
atomic_or_uint(&vp->v_usecount, VUSECOUNT_GATE);
} else {
atomic_and_uint(&vp->v_usecount, ~VUSECOUNT_GATE);
}
atomic_store_relaxed(&vip->vi_state, to);
if (from == VS_LOADING)
cv_broadcast(&vcache_cv);
if (to == VS_LOADED || to == VS_RECLAIMED)
cv_broadcast(&vp->v_cv);
}
#else /* defined(DIAGNOSTIC) */
#define VSTATE_GET(vp) \
(VNODE_TO_VIMPL((vp))->vi_state)
#define VSTATE_CHANGE(vp, from, to) \
vstate_change((vp), (from), (to))
#define VSTATE_WAIT_STABLE(vp) \
vstate_wait_stable((vp))
void
_vstate_assert(vnode_t *vp, enum vnode_state state, const char *func, int line,
bool has_lock)
{
}
static void
vstate_wait_stable(vnode_t *vp)
{
vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
while (vip->vi_state != VS_LOADED && vip->vi_state != VS_RECLAIMED)
cv_wait(&vp->v_cv, vp->v_interlock);
}
static void
vstate_change(vnode_t *vp, enum vnode_state from, enum vnode_state to)
{
vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
/* Open/close the gate for vcache_tryvget(). */
if (to == VS_LOADED) {
membar_release();
atomic_or_uint(&vp->v_usecount, VUSECOUNT_GATE);
} else {
atomic_and_uint(&vp->v_usecount, ~VUSECOUNT_GATE);
}
atomic_store_relaxed(&vip->vi_state, to);
if (from == VS_LOADING)
cv_broadcast(&vcache_cv);
if (to == VS_LOADED || to == VS_RECLAIMED)
cv_broadcast(&vp->v_cv);
}
#endif /* defined(DIAGNOSTIC) */
void
vfs_vnode_sysinit(void)
{
int error __diagused, i;
dead_rootmount = vfs_mountalloc(&dead_vfsops, NULL);
KASSERT(dead_rootmount != NULL);
dead_rootmount->mnt_iflag |= IMNT_MPSAFE;
mutex_init(&vdrain_lock, MUTEX_DEFAULT, IPL_NONE);
for (i = 0; i < LRU_COUNT; i++) {
TAILQ_INIT(&lru_list[i]);
}
vcache_init();
cv_init(&vdrain_cv, "vdrain");
cv_init(&vdrain_gen_cv, "vdrainwt");
error = kthread_create(PRI_VM, KTHREAD_MPSAFE, NULL, vdrain_thread,
NULL, &vdrain_lwp, "vdrain");
KASSERTMSG((error == 0), "kthread_create(vdrain) failed: %d", error);
}
/*
* Allocate a new marker vnode.
*/
vnode_t *
vnalloc_marker(struct mount *mp)
{
vnode_impl_t *vip;
vnode_t *vp;
vip = pool_cache_get(vcache_pool, PR_WAITOK);
memset(vip, 0, sizeof(*vip));
vp = VIMPL_TO_VNODE(vip);
uvm_obj_init(&vp->v_uobj, &uvm_vnodeops, true, 1);
vp->v_mount = mp;
vp->v_type = VBAD;
vp->v_interlock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE);
klist_init(&vip->vi_klist.vk_klist);
vp->v_klist = &vip->vi_klist;
vip->vi_state = VS_MARKER;
return vp;
}
/*
* Free a marker vnode.
*/
void
vnfree_marker(vnode_t *vp)
{
vnode_impl_t *vip;
vip = VNODE_TO_VIMPL(vp);
KASSERT(vip->vi_state == VS_MARKER);
mutex_obj_free(vp->v_interlock);
uvm_obj_destroy(&vp->v_uobj, true);
klist_fini(&vip->vi_klist.vk_klist);
pool_cache_put(vcache_pool, vip);
}
/*
* Test a vnode for being a marker vnode.
*/
bool
vnis_marker(vnode_t *vp)
{
return (VNODE_TO_VIMPL(vp)->vi_state == VS_MARKER);
}
/*
* Return the lru list this node should be on.
*/
static vnodelst_t *
lru_which(vnode_t *vp)
{
KASSERT(mutex_owned(vp->v_interlock));
if (vp->v_holdcnt > 0)
return &lru_list[LRU_HOLD];
else
return &lru_list[LRU_FREE];
}
/*
* Put vnode to end of given list.
* Both the current and the new list may be NULL, used on vnode alloc/free.
* Adjust numvnodes and signal vdrain thread if there is work.
*/
static void
lru_requeue(vnode_t *vp, vnodelst_t *listhd)
{
vnode_impl_t *vip;
int d;
/*
* If the vnode is on the correct list, and was put there recently,
* then leave it be, thus avoiding huge cache and lock contention.
*/
vip = VNODE_TO_VIMPL(vp);
if (listhd == vip->vi_lrulisthd &&
(getticks() - vip->vi_lrulisttm) < hz) {
return;
}
mutex_enter(&vdrain_lock);
d = 0;
if (vip->vi_lrulisthd != NULL)
TAILQ_REMOVE(vip->vi_lrulisthd, vip, vi_lrulist);
else
d++;
vip->vi_lrulisthd = listhd;
vip->vi_lrulisttm = getticks();
if (vip->vi_lrulisthd != NULL)
TAILQ_INSERT_TAIL(vip->vi_lrulisthd, vip, vi_lrulist);
else
d--;
if (d != 0) {
/*
* Looks strange? This is not a bug. Don't store
* numvnodes unless there is a change - avoid false
* sharing on MP.
*/
numvnodes += d;
}
if ((d > 0 && numvnodes > desiredvnodes) ||
listhd == &lru_list[LRU_VRELE])
cv_signal(&vdrain_cv);
mutex_exit(&vdrain_lock);
}
/*
* Release deferred vrele vnodes for this mount.
* Called with file system suspended.
*/
void
vrele_flush(struct mount *mp)
{
vnode_impl_t *vip, *marker;
vnode_t *vp;
int when = 0;
KASSERT(fstrans_is_owner(mp));
marker = VNODE_TO_VIMPL(vnalloc_marker(NULL));
mutex_enter(&vdrain_lock);
TAILQ_INSERT_HEAD(&lru_list[LRU_VRELE], marker, vi_lrulist);
while ((vip = TAILQ_NEXT(marker, vi_lrulist))) {
TAILQ_REMOVE(&lru_list[LRU_VRELE], marker, vi_lrulist);
TAILQ_INSERT_AFTER(&lru_list[LRU_VRELE], vip, marker,
vi_lrulist);
vp = VIMPL_TO_VNODE(vip);
if (vnis_marker(vp))
continue;
KASSERT(vip->vi_lrulisthd == &lru_list[LRU_VRELE]);
TAILQ_REMOVE(vip->vi_lrulisthd, vip, vi_lrulist);
vip->vi_lrulisthd = &lru_list[LRU_HOLD];
vip->vi_lrulisttm = getticks();
TAILQ_INSERT_TAIL(vip->vi_lrulisthd, vip, vi_lrulist);
mutex_exit(&vdrain_lock);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
mutex_enter(vp->v_interlock);
vrelel(vp, 0, LK_EXCLUSIVE);
if (getticks() > when) {
yield();
when = getticks() + hz / 10;
}
mutex_enter(&vdrain_lock);
}
TAILQ_REMOVE(&lru_list[LRU_VRELE], marker, vi_lrulist);
mutex_exit(&vdrain_lock);
vnfree_marker(VIMPL_TO_VNODE(marker));
}
/*
* Reclaim a cached vnode. Used from vdrain_thread only.
*/
static __inline void
vdrain_remove(vnode_t *vp)
{
struct mount *mp;
KASSERT(mutex_owned(&vdrain_lock));
/* Probe usecount (unlocked). */
if (vrefcnt(vp) > 0)
return;
/* Try v_interlock -- we lock the wrong direction! */
if (!mutex_tryenter(vp->v_interlock))
return;
/* Probe usecount and state. */
if (vrefcnt(vp) > 0 || VSTATE_GET(vp) != VS_LOADED) {
mutex_exit(vp->v_interlock);
return;
}
mp = vp->v_mount;
if (fstrans_start_nowait(mp) != 0) {
mutex_exit(vp->v_interlock);
return;
}
vdrain_retry = true;
mutex_exit(&vdrain_lock);
if (vcache_vget(vp) == 0) {
if (!vrecycle(vp)) {
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
mutex_enter(vp->v_interlock);
vrelel(vp, 0, LK_EXCLUSIVE);
}
}
fstrans_done(mp);
mutex_enter(&vdrain_lock);
}
/*
* Release a cached vnode. Used from vdrain_thread only.
*/
static __inline void
vdrain_vrele(vnode_t *vp)
{
vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
struct mount *mp;
KASSERT(mutex_owned(&vdrain_lock));
mp = vp->v_mount;
if (fstrans_start_nowait(mp) != 0)
return;
/*
* First remove the vnode from the vrele list.
* Put it on the last lru list, the last vrele()
* will put it back onto the right list before
* its usecount reaches zero.
*/
KASSERT(vip->vi_lrulisthd == &lru_list[LRU_VRELE]);
TAILQ_REMOVE(vip->vi_lrulisthd, vip, vi_lrulist);
vip->vi_lrulisthd = &lru_list[LRU_HOLD];
vip->vi_lrulisttm = getticks();
TAILQ_INSERT_TAIL(vip->vi_lrulisthd, vip, vi_lrulist);
vdrain_retry = true;
mutex_exit(&vdrain_lock);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
mutex_enter(vp->v_interlock);
vrelel(vp, 0, LK_EXCLUSIVE);
fstrans_done(mp);
mutex_enter(&vdrain_lock);
}
/*
* Helper thread to keep the number of vnodes below desiredvnodes
* and release vnodes from asynchronous vrele.
*/
static void
vdrain_thread(void *cookie)
{
int i;
u_int target;
vnode_impl_t *vip, *marker;
marker = VNODE_TO_VIMPL(vnalloc_marker(NULL));
mutex_enter(&vdrain_lock);
for (;;) {
vdrain_retry = false;
target = desiredvnodes - desiredvnodes/10;
for (i = 0; i < LRU_COUNT; i++) {
TAILQ_INSERT_HEAD(&lru_list[i], marker, vi_lrulist);
while ((vip = TAILQ_NEXT(marker, vi_lrulist))) {
TAILQ_REMOVE(&lru_list[i], marker, vi_lrulist);
TAILQ_INSERT_AFTER(&lru_list[i], vip, marker,
vi_lrulist);
if (vnis_marker(VIMPL_TO_VNODE(vip)))
continue;
if (i == LRU_VRELE)
vdrain_vrele(VIMPL_TO_VNODE(vip));
else if (numvnodes < target)
break;
else
vdrain_remove(VIMPL_TO_VNODE(vip));
}
TAILQ_REMOVE(&lru_list[i], marker, vi_lrulist);
}
if (vdrain_retry) {
kpause("vdrainrt", false, 1, &vdrain_lock);
} else {
vdrain_gen++;
cv_broadcast(&vdrain_gen_cv);
cv_wait(&vdrain_cv, &vdrain_lock);
}
}
}
/*
* Try to drop reference on a vnode. Abort if we are releasing the
* last reference. Note: this _must_ succeed if not the last reference.
*/
static bool
vtryrele(vnode_t *vp)
{
u_int use, next;
membar_release();
for (use = atomic_load_relaxed(&vp->v_usecount);; use = next) {
if (__predict_false((use & VUSECOUNT_MASK) == 1)) {
return false;
}
KASSERT((use & VUSECOUNT_MASK) > 1);
next = atomic_cas_uint(&vp->v_usecount, use, use - 1);
if (__predict_true(next == use)) {
return true;
}
}
}
/*
* vput: unlock and release the reference.
*/
void
vput(vnode_t *vp)
{
int lktype;
/*
* Do an unlocked check of the usecount. If it looks like we're not
* about to drop the last reference, then unlock the vnode and try
* to drop the reference. If it ends up being the last reference
* after all, vrelel() can fix it all up. Most of the time this
* will all go to plan.
*/
if (vrefcnt(vp) > 1) {
VOP_UNLOCK(vp);
if (vtryrele(vp)) {
return;
}
lktype = LK_NONE;
} else {
lktype = VOP_ISLOCKED(vp);
KASSERT(lktype != LK_NONE);
}
mutex_enter(vp->v_interlock);
vrelel(vp, 0, lktype);
}
/*
* Vnode release. If reference count drops to zero, call inactive
* routine and either return to freelist or free to the pool.
*/
static void
vrelel(vnode_t *vp, int flags, int lktype)
{
const bool async = ((flags & VRELEL_ASYNC) != 0);
bool recycle, defer, objlock_held;
u_int use, next;
int error;
objlock_held = false;
retry:
KASSERT(mutex_owned(vp->v_interlock));
if (__predict_false(vp->v_op == dead_vnodeop_p &&
VSTATE_GET(vp) != VS_RECLAIMED)) {
vnpanic(vp, "dead but not clean");
}
/*
* If not the last reference, just unlock and drop the reference count.
*
* Otherwise make sure we pass a point in time where we hold the
* last reference with VGET flag unset.
*/
for (use = atomic_load_relaxed(&vp->v_usecount);; use = next) {
if (__predict_false((use & VUSECOUNT_MASK) > 1)) {
if (objlock_held) {
objlock_held = false;
rw_exit(vp->v_uobj.vmobjlock);
}
if (lktype != LK_NONE) {
mutex_exit(vp->v_interlock);
lktype = LK_NONE;
VOP_UNLOCK(vp);
mutex_enter(vp->v_interlock);
}
if (vtryrele(vp)) {
mutex_exit(vp->v_interlock);
return;
}
next = atomic_load_relaxed(&vp->v_usecount);
continue;
}
KASSERT((use & VUSECOUNT_MASK) == 1);
next = use & ~VUSECOUNT_VGET;
if (next != use) {
next = atomic_cas_uint(&vp->v_usecount, use, next);
}
if (__predict_true(next == use)) {
break;
}
}
membar_acquire();
if (vrefcnt(vp) <= 0 || vp->v_writecount != 0) {
vnpanic(vp, "%s: bad ref count", __func__);
}
#ifdef DIAGNOSTIC
if ((vp->v_type == VBLK || vp->v_type == VCHR) &&
vp->v_specnode != NULL && vp->v_specnode->sn_opencnt != 0) {
vprint("vrelel: missing VOP_CLOSE()", vp);
}
#endif
/*
* If already clean there is no need to lock, defer or
* deactivate this node.
*/
if (VSTATE_GET(vp) == VS_RECLAIMED) {
if (objlock_held) {
objlock_held = false;
rw_exit(vp->v_uobj.vmobjlock);
}
if (lktype != LK_NONE) {
mutex_exit(vp->v_interlock);
lktype = LK_NONE;
VOP_UNLOCK(vp);
mutex_enter(vp->v_interlock);
}
goto out;
}
/*
* First try to get the vnode locked for VOP_INACTIVE().
* Defer vnode release to vdrain_thread if caller requests
* it explicitly, is the pagedaemon or the lock failed.
*/
defer = false;
if ((curlwp == uvm.pagedaemon_lwp) || async) {
defer = true;
} else if (lktype == LK_SHARED) {
/* Excellent chance of getting, if the last ref. */
error = vn_lock(vp, LK_UPGRADE | LK_RETRY | LK_NOWAIT);
if (error != 0) {
defer = true;
} else {
lktype = LK_EXCLUSIVE;
}
} else if (lktype == LK_NONE) {
/* Excellent chance of getting, if the last ref. */
error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY | LK_NOWAIT);
if (error != 0) {
defer = true;
} else {
lktype = LK_EXCLUSIVE;
}
}
KASSERT(mutex_owned(vp->v_interlock));
if (defer) {
/*
* Defer reclaim to the kthread; it's not safe to
* clean it here. We donate it our last reference.
*/
if (lktype != LK_NONE) {
mutex_exit(vp->v_interlock);
VOP_UNLOCK(vp);
mutex_enter(vp->v_interlock);
}
lru_requeue(vp, &lru_list[LRU_VRELE]);
mutex_exit(vp->v_interlock);
return;
}
KASSERT(lktype == LK_EXCLUSIVE);
/* If the node gained another reference, retry. */
use = atomic_load_relaxed(&vp->v_usecount);
if ((use & VUSECOUNT_VGET) != 0) {
goto retry;
}
KASSERT((use & VUSECOUNT_MASK) == 1);
if ((vp->v_iflag & (VI_TEXT|VI_EXECMAP|VI_WRMAP)) != 0 ||
(vp->v_vflag & VV_MAPPED) != 0) {
/* Take care of space accounting. */
if (!objlock_held) {
objlock_held = true;
if (!rw_tryenter(vp->v_uobj.vmobjlock, RW_WRITER)) {
mutex_exit(vp->v_interlock);
rw_enter(vp->v_uobj.vmobjlock, RW_WRITER);
mutex_enter(vp->v_interlock);
goto retry;
}
}
if ((vp->v_iflag & VI_EXECMAP) != 0) {
cpu_count(CPU_COUNT_EXECPAGES, -vp->v_uobj.uo_npages);
}
vp->v_iflag &= ~(VI_TEXT|VI_EXECMAP|VI_WRMAP);
vp->v_vflag &= ~VV_MAPPED;
}
if (objlock_held) {
objlock_held = false;
rw_exit(vp->v_uobj.vmobjlock);
}
/*
* Deactivate the vnode, but preserve our reference across
* the call to VOP_INACTIVE().
*
* If VOP_INACTIVE() indicates that the file has been
* deleted, then recycle the vnode.
*
* Note that VOP_INACTIVE() will not drop the vnode lock.
*/
mutex_exit(vp->v_interlock);
recycle = false;
VOP_INACTIVE(vp, &recycle);
if (!recycle) {
lktype = LK_NONE;
VOP_UNLOCK(vp);
}
mutex_enter(vp->v_interlock);
/*
* Block new references then check again to see if a
* new reference was acquired in the meantime. If
* it was, restore the vnode state and try again.
*/
if (recycle) {
VSTATE_CHANGE(vp, VS_LOADED, VS_BLOCKED);
use = atomic_load_relaxed(&vp->v_usecount);
if ((use & VUSECOUNT_VGET) != 0) {
VSTATE_CHANGE(vp, VS_BLOCKED, VS_LOADED);
goto retry;
}
KASSERT((use & VUSECOUNT_MASK) == 1);
}
/*
* Recycle the vnode if the file is now unused (unlinked).
*/
if (recycle) {
VSTATE_ASSERT(vp, VS_BLOCKED);
KASSERT(lktype == LK_EXCLUSIVE);
/* vcache_reclaim drops the lock. */
lktype = LK_NONE;
vcache_reclaim(vp);
}
KASSERT(vrefcnt(vp) > 0);
KASSERT(lktype == LK_NONE);
out:
for (use = atomic_load_relaxed(&vp->v_usecount);; use = next) {
if (__predict_false((use & VUSECOUNT_VGET) != 0 &&
(use & VUSECOUNT_MASK) == 1)) {
/* Gained and released another reference, retry. */
goto retry;
}
next = atomic_cas_uint(&vp->v_usecount, use, use - 1);
if (__predict_true(next == use)) {
if (__predict_false((use & VUSECOUNT_MASK) != 1)) {
/* Gained another reference. */
mutex_exit(vp->v_interlock);
return;
}
break;
}
}
membar_acquire();
if (VSTATE_GET(vp) == VS_RECLAIMED && vp->v_holdcnt == 0) {
/*
* It's clean so destroy it. It isn't referenced
* anywhere since it has been reclaimed.
*/