forked from grate-driver/linux
-
Notifications
You must be signed in to change notification settings - Fork 0
/
dquot.c
2410 lines (2183 loc) · 67.5 KB
/
dquot.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
/*
* Implementation of the diskquota system for the LINUX operating system. QUOTA
* is implemented using the BSD system call interface as the means of
* communication with the user level. This file contains the generic routines
* called by the different filesystems on allocation of an inode or block.
* These routines take care of the administration needed to have a consistent
* diskquota tracking system. The ideas of both user and group quotas are based
* on the Melbourne quota system as used on BSD derived systems. The internal
* implementation is based on one of the several variants of the LINUX
* inode-subsystem with added complexity of the diskquota system.
*
* Author: Marco van Wieringen <mvw@planets.elm.net>
*
* Fixes: Dmitry Gorodchanin <pgmdsg@ibi.com>, 11 Feb 96
*
* Revised list management to avoid races
* -- Bill Hawes, <whawes@star.net>, 9/98
*
* Fixed races in dquot_transfer(), dqget() and dquot_alloc_...().
* As the consequence the locking was moved from dquot_decr_...(),
* dquot_incr_...() to calling functions.
* invalidate_dquots() now writes modified dquots.
* Serialized quota_off() and quota_on() for mount point.
* Fixed a few bugs in grow_dquots().
* Fixed deadlock in write_dquot() - we no longer account quotas on
* quota files
* remove_dquot_ref() moved to inode.c - it now traverses through inodes
* add_dquot_ref() restarts after blocking
* Added check for bogus uid and fixed check for group in quotactl.
* Jan Kara, <jack@suse.cz>, sponsored by SuSE CR, 10-11/99
*
* Used struct list_head instead of own list struct
* Invalidation of referenced dquots is no longer possible
* Improved free_dquots list management
* Quota and i_blocks are now updated in one place to avoid races
* Warnings are now delayed so we won't block in critical section
* Write updated not to require dquot lock
* Jan Kara, <jack@suse.cz>, 9/2000
*
* Added dynamic quota structure allocation
* Jan Kara <jack@suse.cz> 12/2000
*
* Rewritten quota interface. Implemented new quota format and
* formats registering.
* Jan Kara, <jack@suse.cz>, 2001,2002
*
* New SMP locking.
* Jan Kara, <jack@suse.cz>, 10/2002
*
* Added journalled quota support, fix lock inversion problems
* Jan Kara, <jack@suse.cz>, 2003,2004
*
* (C) Copyright 1994 - 1997 Marco van Wieringen
*/
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/mm.h>
#include <linux/time.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/tty.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/security.h>
#include <linux/kmod.h>
#include <linux/namei.h>
#include <linux/buffer_head.h>
#include <linux/capability.h>
#include <linux/quotaops.h>
#include <linux/writeback.h> /* for inode_lock, oddly enough.. */
#ifdef CONFIG_QUOTA_NETLINK_INTERFACE
#include <net/netlink.h>
#include <net/genetlink.h>
#endif
#include <asm/uaccess.h>
#define __DQUOT_PARANOIA
/*
* There are three quota SMP locks. dq_list_lock protects all lists with quotas
* and quota formats, dqstats structure containing statistics about the lists
* dq_data_lock protects data from dq_dqb and also mem_dqinfo structures and
* also guards consistency of dquot->dq_dqb with inode->i_blocks, i_bytes.
* i_blocks and i_bytes updates itself are guarded by i_lock acquired directly
* in inode_add_bytes() and inode_sub_bytes(). dq_state_lock protects
* modifications of quota state (on quotaon and quotaoff) and readers who care
* about latest values take it as well.
*
* The spinlock ordering is hence: dq_data_lock > dq_list_lock > i_lock,
* dq_list_lock > dq_state_lock
*
* Note that some things (eg. sb pointer, type, id) doesn't change during
* the life of the dquot structure and so needn't to be protected by a lock
*
* Any operation working on dquots via inode pointers must hold dqptr_sem. If
* operation is just reading pointers from inode (or not using them at all) the
* read lock is enough. If pointers are altered function must hold write lock
* (these locking rules also apply for S_NOQUOTA flag in the inode - note that
* for altering the flag i_mutex is also needed).
*
* Each dquot has its dq_lock mutex. Locked dquots might not be referenced
* from inodes (dquot_alloc_space() and such don't check the dq_lock).
* Currently dquot is locked only when it is being read to memory (or space for
* it is being allocated) on the first dqget() and when it is being released on
* the last dqput(). The allocation and release oparations are serialized by
* the dq_lock and by checking the use count in dquot_release(). Write
* operations on dquots don't hold dq_lock as they copy data under dq_data_lock
* spinlock to internal buffers before writing.
*
* Lock ordering (including related VFS locks) is the following:
* i_mutex > dqonoff_sem > journal_lock > dqptr_sem > dquot->dq_lock >
* dqio_mutex
* The lock ordering of dqptr_sem imposed by quota code is only dqonoff_sem >
* dqptr_sem. But filesystem has to count with the fact that functions such as
* dquot_alloc_space() acquire dqptr_sem and they usually have to be called
* from inside a transaction to keep filesystem consistency after a crash. Also
* filesystems usually want to do some IO on dquot from ->mark_dirty which is
* called with dqptr_sem held.
* i_mutex on quota files is special (it's below dqio_mutex)
*/
static DEFINE_SPINLOCK(dq_list_lock);
static DEFINE_SPINLOCK(dq_state_lock);
DEFINE_SPINLOCK(dq_data_lock);
static char *quotatypes[] = INITQFNAMES;
static struct quota_format_type *quota_formats; /* List of registered formats */
static struct quota_module_name module_names[] = INIT_QUOTA_MODULE_NAMES;
/* SLAB cache for dquot structures */
static struct kmem_cache *dquot_cachep;
int register_quota_format(struct quota_format_type *fmt)
{
spin_lock(&dq_list_lock);
fmt->qf_next = quota_formats;
quota_formats = fmt;
spin_unlock(&dq_list_lock);
return 0;
}
void unregister_quota_format(struct quota_format_type *fmt)
{
struct quota_format_type **actqf;
spin_lock(&dq_list_lock);
for (actqf = "a_formats; *actqf && *actqf != fmt; actqf = &(*actqf)->qf_next);
if (*actqf)
*actqf = (*actqf)->qf_next;
spin_unlock(&dq_list_lock);
}
static struct quota_format_type *find_quota_format(int id)
{
struct quota_format_type *actqf;
spin_lock(&dq_list_lock);
for (actqf = quota_formats; actqf && actqf->qf_fmt_id != id; actqf = actqf->qf_next);
if (!actqf || !try_module_get(actqf->qf_owner)) {
int qm;
spin_unlock(&dq_list_lock);
for (qm = 0; module_names[qm].qm_fmt_id && module_names[qm].qm_fmt_id != id; qm++);
if (!module_names[qm].qm_fmt_id || request_module(module_names[qm].qm_mod_name))
return NULL;
spin_lock(&dq_list_lock);
for (actqf = quota_formats; actqf && actqf->qf_fmt_id != id; actqf = actqf->qf_next);
if (actqf && !try_module_get(actqf->qf_owner))
actqf = NULL;
}
spin_unlock(&dq_list_lock);
return actqf;
}
static void put_quota_format(struct quota_format_type *fmt)
{
module_put(fmt->qf_owner);
}
/*
* Dquot List Management:
* The quota code uses three lists for dquot management: the inuse_list,
* free_dquots, and dquot_hash[] array. A single dquot structure may be
* on all three lists, depending on its current state.
*
* All dquots are placed to the end of inuse_list when first created, and this
* list is used for invalidate operation, which must look at every dquot.
*
* Unused dquots (dq_count == 0) are added to the free_dquots list when freed,
* and this list is searched whenever we need an available dquot. Dquots are
* removed from the list as soon as they are used again, and
* dqstats.free_dquots gives the number of dquots on the list. When
* dquot is invalidated it's completely released from memory.
*
* Dquots with a specific identity (device, type and id) are placed on
* one of the dquot_hash[] hash chains. The provides an efficient search
* mechanism to locate a specific dquot.
*/
static LIST_HEAD(inuse_list);
static LIST_HEAD(free_dquots);
static unsigned int dq_hash_bits, dq_hash_mask;
static struct hlist_head *dquot_hash;
struct dqstats dqstats;
static inline unsigned int
hashfn(const struct super_block *sb, unsigned int id, int type)
{
unsigned long tmp;
tmp = (((unsigned long)sb>>L1_CACHE_SHIFT) ^ id) * (MAXQUOTAS - type);
return (tmp + (tmp >> dq_hash_bits)) & dq_hash_mask;
}
/*
* Following list functions expect dq_list_lock to be held
*/
static inline void insert_dquot_hash(struct dquot *dquot)
{
struct hlist_head *head = dquot_hash + hashfn(dquot->dq_sb, dquot->dq_id, dquot->dq_type);
hlist_add_head(&dquot->dq_hash, head);
}
static inline void remove_dquot_hash(struct dquot *dquot)
{
hlist_del_init(&dquot->dq_hash);
}
static inline struct dquot *find_dquot(unsigned int hashent, struct super_block *sb, unsigned int id, int type)
{
struct hlist_node *node;
struct dquot *dquot;
hlist_for_each (node, dquot_hash+hashent) {
dquot = hlist_entry(node, struct dquot, dq_hash);
if (dquot->dq_sb == sb && dquot->dq_id == id && dquot->dq_type == type)
return dquot;
}
return NODQUOT;
}
/* Add a dquot to the tail of the free list */
static inline void put_dquot_last(struct dquot *dquot)
{
list_add_tail(&dquot->dq_free, &free_dquots);
dqstats.free_dquots++;
}
static inline void remove_free_dquot(struct dquot *dquot)
{
if (list_empty(&dquot->dq_free))
return;
list_del_init(&dquot->dq_free);
dqstats.free_dquots--;
}
static inline void put_inuse(struct dquot *dquot)
{
/* We add to the back of inuse list so we don't have to restart
* when traversing this list and we block */
list_add_tail(&dquot->dq_inuse, &inuse_list);
dqstats.allocated_dquots++;
}
static inline void remove_inuse(struct dquot *dquot)
{
dqstats.allocated_dquots--;
list_del(&dquot->dq_inuse);
}
/*
* End of list functions needing dq_list_lock
*/
static void wait_on_dquot(struct dquot *dquot)
{
mutex_lock(&dquot->dq_lock);
mutex_unlock(&dquot->dq_lock);
}
static inline int dquot_dirty(struct dquot *dquot)
{
return test_bit(DQ_MOD_B, &dquot->dq_flags);
}
static inline int mark_dquot_dirty(struct dquot *dquot)
{
return dquot->dq_sb->dq_op->mark_dirty(dquot);
}
int dquot_mark_dquot_dirty(struct dquot *dquot)
{
spin_lock(&dq_list_lock);
if (!test_and_set_bit(DQ_MOD_B, &dquot->dq_flags))
list_add(&dquot->dq_dirty, &sb_dqopt(dquot->dq_sb)->
info[dquot->dq_type].dqi_dirty_list);
spin_unlock(&dq_list_lock);
return 0;
}
/* This function needs dq_list_lock */
static inline int clear_dquot_dirty(struct dquot *dquot)
{
if (!test_and_clear_bit(DQ_MOD_B, &dquot->dq_flags))
return 0;
list_del_init(&dquot->dq_dirty);
return 1;
}
void mark_info_dirty(struct super_block *sb, int type)
{
set_bit(DQF_INFO_DIRTY_B, &sb_dqopt(sb)->info[type].dqi_flags);
}
EXPORT_SYMBOL(mark_info_dirty);
/*
* Read dquot from disk and alloc space for it
*/
int dquot_acquire(struct dquot *dquot)
{
int ret = 0, ret2 = 0;
struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
mutex_lock(&dquot->dq_lock);
mutex_lock(&dqopt->dqio_mutex);
if (!test_bit(DQ_READ_B, &dquot->dq_flags))
ret = dqopt->ops[dquot->dq_type]->read_dqblk(dquot);
if (ret < 0)
goto out_iolock;
set_bit(DQ_READ_B, &dquot->dq_flags);
/* Instantiate dquot if needed */
if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && !dquot->dq_off) {
ret = dqopt->ops[dquot->dq_type]->commit_dqblk(dquot);
/* Write the info if needed */
if (info_dirty(&dqopt->info[dquot->dq_type]))
ret2 = dqopt->ops[dquot->dq_type]->write_file_info(dquot->dq_sb, dquot->dq_type);
if (ret < 0)
goto out_iolock;
if (ret2 < 0) {
ret = ret2;
goto out_iolock;
}
}
set_bit(DQ_ACTIVE_B, &dquot->dq_flags);
out_iolock:
mutex_unlock(&dqopt->dqio_mutex);
mutex_unlock(&dquot->dq_lock);
return ret;
}
/*
* Write dquot to disk
*/
int dquot_commit(struct dquot *dquot)
{
int ret = 0, ret2 = 0;
struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
mutex_lock(&dqopt->dqio_mutex);
spin_lock(&dq_list_lock);
if (!clear_dquot_dirty(dquot)) {
spin_unlock(&dq_list_lock);
goto out_sem;
}
spin_unlock(&dq_list_lock);
/* Inactive dquot can be only if there was error during read/init
* => we have better not writing it */
if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
ret = dqopt->ops[dquot->dq_type]->commit_dqblk(dquot);
if (info_dirty(&dqopt->info[dquot->dq_type]))
ret2 = dqopt->ops[dquot->dq_type]->write_file_info(dquot->dq_sb, dquot->dq_type);
if (ret >= 0)
ret = ret2;
}
out_sem:
mutex_unlock(&dqopt->dqio_mutex);
return ret;
}
/*
* Release dquot
*/
int dquot_release(struct dquot *dquot)
{
int ret = 0, ret2 = 0;
struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
mutex_lock(&dquot->dq_lock);
/* Check whether we are not racing with some other dqget() */
if (atomic_read(&dquot->dq_count) > 1)
goto out_dqlock;
mutex_lock(&dqopt->dqio_mutex);
if (dqopt->ops[dquot->dq_type]->release_dqblk) {
ret = dqopt->ops[dquot->dq_type]->release_dqblk(dquot);
/* Write the info */
if (info_dirty(&dqopt->info[dquot->dq_type]))
ret2 = dqopt->ops[dquot->dq_type]->write_file_info(dquot->dq_sb, dquot->dq_type);
if (ret >= 0)
ret = ret2;
}
clear_bit(DQ_ACTIVE_B, &dquot->dq_flags);
mutex_unlock(&dqopt->dqio_mutex);
out_dqlock:
mutex_unlock(&dquot->dq_lock);
return ret;
}
void dquot_destroy(struct dquot *dquot)
{
kmem_cache_free(dquot_cachep, dquot);
}
EXPORT_SYMBOL(dquot_destroy);
static inline void do_destroy_dquot(struct dquot *dquot)
{
dquot->dq_sb->dq_op->destroy_dquot(dquot);
}
/* Invalidate all dquots on the list. Note that this function is called after
* quota is disabled and pointers from inodes removed so there cannot be new
* quota users. There can still be some users of quotas due to inodes being
* just deleted or pruned by prune_icache() (those are not attached to any
* list) or parallel quotactl call. We have to wait for such users.
*/
static void invalidate_dquots(struct super_block *sb, int type)
{
struct dquot *dquot, *tmp;
restart:
spin_lock(&dq_list_lock);
list_for_each_entry_safe(dquot, tmp, &inuse_list, dq_inuse) {
if (dquot->dq_sb != sb)
continue;
if (dquot->dq_type != type)
continue;
/* Wait for dquot users */
if (atomic_read(&dquot->dq_count)) {
DEFINE_WAIT(wait);
atomic_inc(&dquot->dq_count);
prepare_to_wait(&dquot->dq_wait_unused, &wait,
TASK_UNINTERRUPTIBLE);
spin_unlock(&dq_list_lock);
/* Once dqput() wakes us up, we know it's time to free
* the dquot.
* IMPORTANT: we rely on the fact that there is always
* at most one process waiting for dquot to free.
* Otherwise dq_count would be > 1 and we would never
* wake up.
*/
if (atomic_read(&dquot->dq_count) > 1)
schedule();
finish_wait(&dquot->dq_wait_unused, &wait);
dqput(dquot);
/* At this moment dquot() need not exist (it could be
* reclaimed by prune_dqcache(). Hence we must
* restart. */
goto restart;
}
/*
* Quota now has no users and it has been written on last
* dqput()
*/
remove_dquot_hash(dquot);
remove_free_dquot(dquot);
remove_inuse(dquot);
do_destroy_dquot(dquot);
}
spin_unlock(&dq_list_lock);
}
/* Call callback for every active dquot on given filesystem */
int dquot_scan_active(struct super_block *sb,
int (*fn)(struct dquot *dquot, unsigned long priv),
unsigned long priv)
{
struct dquot *dquot, *old_dquot = NULL;
int ret = 0;
mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
spin_lock(&dq_list_lock);
list_for_each_entry(dquot, &inuse_list, dq_inuse) {
if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
continue;
if (dquot->dq_sb != sb)
continue;
/* Now we have active dquot so we can just increase use count */
atomic_inc(&dquot->dq_count);
dqstats.lookups++;
spin_unlock(&dq_list_lock);
dqput(old_dquot);
old_dquot = dquot;
ret = fn(dquot, priv);
if (ret < 0)
goto out;
spin_lock(&dq_list_lock);
/* We are safe to continue now because our dquot could not
* be moved out of the inuse list while we hold the reference */
}
spin_unlock(&dq_list_lock);
out:
dqput(old_dquot);
mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
return ret;
}
int vfs_quota_sync(struct super_block *sb, int type)
{
struct list_head *dirty;
struct dquot *dquot;
struct quota_info *dqopt = sb_dqopt(sb);
int cnt;
mutex_lock(&dqopt->dqonoff_mutex);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (type != -1 && cnt != type)
continue;
if (!sb_has_quota_active(sb, cnt))
continue;
spin_lock(&dq_list_lock);
dirty = &dqopt->info[cnt].dqi_dirty_list;
while (!list_empty(dirty)) {
dquot = list_first_entry(dirty, struct dquot, dq_dirty);
/* Dirty and inactive can be only bad dquot... */
if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
clear_dquot_dirty(dquot);
continue;
}
/* Now we have active dquot from which someone is
* holding reference so we can safely just increase
* use count */
atomic_inc(&dquot->dq_count);
dqstats.lookups++;
spin_unlock(&dq_list_lock);
sb->dq_op->write_dquot(dquot);
dqput(dquot);
spin_lock(&dq_list_lock);
}
spin_unlock(&dq_list_lock);
}
for (cnt = 0; cnt < MAXQUOTAS; cnt++)
if ((cnt == type || type == -1) && sb_has_quota_active(sb, cnt)
&& info_dirty(&dqopt->info[cnt]))
sb->dq_op->write_info(sb, cnt);
spin_lock(&dq_list_lock);
dqstats.syncs++;
spin_unlock(&dq_list_lock);
mutex_unlock(&dqopt->dqonoff_mutex);
return 0;
}
/* Free unused dquots from cache */
static void prune_dqcache(int count)
{
struct list_head *head;
struct dquot *dquot;
head = free_dquots.prev;
while (head != &free_dquots && count) {
dquot = list_entry(head, struct dquot, dq_free);
remove_dquot_hash(dquot);
remove_free_dquot(dquot);
remove_inuse(dquot);
do_destroy_dquot(dquot);
count--;
head = free_dquots.prev;
}
}
/*
* This is called from kswapd when we think we need some
* more memory
*/
static int shrink_dqcache_memory(int nr, gfp_t gfp_mask)
{
if (nr) {
spin_lock(&dq_list_lock);
prune_dqcache(nr);
spin_unlock(&dq_list_lock);
}
return (dqstats.free_dquots / 100) * sysctl_vfs_cache_pressure;
}
static struct shrinker dqcache_shrinker = {
.shrink = shrink_dqcache_memory,
.seeks = DEFAULT_SEEKS,
};
/*
* Put reference to dquot
* NOTE: If you change this function please check whether dqput_blocks() works right...
*/
void dqput(struct dquot *dquot)
{
int ret;
if (!dquot)
return;
#ifdef __DQUOT_PARANOIA
if (!atomic_read(&dquot->dq_count)) {
printk("VFS: dqput: trying to free free dquot\n");
printk("VFS: device %s, dquot of %s %d\n",
dquot->dq_sb->s_id,
quotatypes[dquot->dq_type],
dquot->dq_id);
BUG();
}
#endif
spin_lock(&dq_list_lock);
dqstats.drops++;
spin_unlock(&dq_list_lock);
we_slept:
spin_lock(&dq_list_lock);
if (atomic_read(&dquot->dq_count) > 1) {
/* We have more than one user... nothing to do */
atomic_dec(&dquot->dq_count);
/* Releasing dquot during quotaoff phase? */
if (!sb_has_quota_active(dquot->dq_sb, dquot->dq_type) &&
atomic_read(&dquot->dq_count) == 1)
wake_up(&dquot->dq_wait_unused);
spin_unlock(&dq_list_lock);
return;
}
/* Need to release dquot? */
if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && dquot_dirty(dquot)) {
spin_unlock(&dq_list_lock);
/* Commit dquot before releasing */
ret = dquot->dq_sb->dq_op->write_dquot(dquot);
if (ret < 0) {
printk(KERN_ERR "VFS: cannot write quota structure on "
"device %s (error %d). Quota may get out of "
"sync!\n", dquot->dq_sb->s_id, ret);
/*
* We clear dirty bit anyway, so that we avoid
* infinite loop here
*/
spin_lock(&dq_list_lock);
clear_dquot_dirty(dquot);
spin_unlock(&dq_list_lock);
}
goto we_slept;
}
/* Clear flag in case dquot was inactive (something bad happened) */
clear_dquot_dirty(dquot);
if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
spin_unlock(&dq_list_lock);
dquot->dq_sb->dq_op->release_dquot(dquot);
goto we_slept;
}
atomic_dec(&dquot->dq_count);
#ifdef __DQUOT_PARANOIA
/* sanity check */
BUG_ON(!list_empty(&dquot->dq_free));
#endif
put_dquot_last(dquot);
spin_unlock(&dq_list_lock);
}
struct dquot *dquot_alloc(struct super_block *sb, int type)
{
return kmem_cache_zalloc(dquot_cachep, GFP_NOFS);
}
EXPORT_SYMBOL(dquot_alloc);
static struct dquot *get_empty_dquot(struct super_block *sb, int type)
{
struct dquot *dquot;
dquot = sb->dq_op->alloc_dquot(sb, type);
if(!dquot)
return NODQUOT;
mutex_init(&dquot->dq_lock);
INIT_LIST_HEAD(&dquot->dq_free);
INIT_LIST_HEAD(&dquot->dq_inuse);
INIT_HLIST_NODE(&dquot->dq_hash);
INIT_LIST_HEAD(&dquot->dq_dirty);
init_waitqueue_head(&dquot->dq_wait_unused);
dquot->dq_sb = sb;
dquot->dq_type = type;
atomic_set(&dquot->dq_count, 1);
return dquot;
}
/*
* Get reference to dquot
*
* Locking is slightly tricky here. We are guarded from parallel quotaoff()
* destroying our dquot by:
* a) checking for quota flags under dq_list_lock and
* b) getting a reference to dquot before we release dq_list_lock
*/
struct dquot *dqget(struct super_block *sb, unsigned int id, int type)
{
unsigned int hashent = hashfn(sb, id, type);
struct dquot *dquot = NODQUOT, *empty = NODQUOT;
if (!sb_has_quota_active(sb, type))
return NODQUOT;
we_slept:
spin_lock(&dq_list_lock);
spin_lock(&dq_state_lock);
if (!sb_has_quota_active(sb, type)) {
spin_unlock(&dq_state_lock);
spin_unlock(&dq_list_lock);
goto out;
}
spin_unlock(&dq_state_lock);
if ((dquot = find_dquot(hashent, sb, id, type)) == NODQUOT) {
if (empty == NODQUOT) {
spin_unlock(&dq_list_lock);
if ((empty = get_empty_dquot(sb, type)) == NODQUOT)
schedule(); /* Try to wait for a moment... */
goto we_slept;
}
dquot = empty;
empty = NODQUOT;
dquot->dq_id = id;
/* all dquots go on the inuse_list */
put_inuse(dquot);
/* hash it first so it can be found */
insert_dquot_hash(dquot);
dqstats.lookups++;
spin_unlock(&dq_list_lock);
} else {
if (!atomic_read(&dquot->dq_count))
remove_free_dquot(dquot);
atomic_inc(&dquot->dq_count);
dqstats.cache_hits++;
dqstats.lookups++;
spin_unlock(&dq_list_lock);
}
/* Wait for dq_lock - after this we know that either dquot_release() is already
* finished or it will be canceled due to dq_count > 1 test */
wait_on_dquot(dquot);
/* Read the dquot and instantiate it (everything done only if needed) */
if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && sb->dq_op->acquire_dquot(dquot) < 0) {
dqput(dquot);
dquot = NODQUOT;
goto out;
}
#ifdef __DQUOT_PARANOIA
BUG_ON(!dquot->dq_sb); /* Has somebody invalidated entry under us? */
#endif
out:
if (empty)
do_destroy_dquot(empty);
return dquot;
}
static int dqinit_needed(struct inode *inode, int type)
{
int cnt;
if (IS_NOQUOTA(inode))
return 0;
if (type != -1)
return inode->i_dquot[type] == NODQUOT;
for (cnt = 0; cnt < MAXQUOTAS; cnt++)
if (inode->i_dquot[cnt] == NODQUOT)
return 1;
return 0;
}
/* This routine is guarded by dqonoff_mutex mutex */
static void add_dquot_ref(struct super_block *sb, int type)
{
struct inode *inode, *old_inode = NULL;
spin_lock(&inode_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
if (!atomic_read(&inode->i_writecount))
continue;
if (!dqinit_needed(inode, type))
continue;
if (inode->i_state & (I_FREEING|I_WILL_FREE))
continue;
__iget(inode);
spin_unlock(&inode_lock);
iput(old_inode);
sb->dq_op->initialize(inode, type);
/* We hold a reference to 'inode' so it couldn't have been
* removed from s_inodes list while we dropped the inode_lock.
* We cannot iput the inode now as we can be holding the last
* reference and we cannot iput it under inode_lock. So we
* keep the reference and iput it later. */
old_inode = inode;
spin_lock(&inode_lock);
}
spin_unlock(&inode_lock);
iput(old_inode);
}
/* Return 0 if dqput() won't block (note that 1 doesn't necessarily mean blocking) */
static inline int dqput_blocks(struct dquot *dquot)
{
if (atomic_read(&dquot->dq_count) <= 1)
return 1;
return 0;
}
/* Remove references to dquots from inode - add dquot to list for freeing if needed */
/* We can't race with anybody because we hold dqptr_sem for writing... */
static int remove_inode_dquot_ref(struct inode *inode, int type,
struct list_head *tofree_head)
{
struct dquot *dquot = inode->i_dquot[type];
inode->i_dquot[type] = NODQUOT;
if (dquot != NODQUOT) {
if (dqput_blocks(dquot)) {
#ifdef __DQUOT_PARANOIA
if (atomic_read(&dquot->dq_count) != 1)
printk(KERN_WARNING "VFS: Adding dquot with dq_count %d to dispose list.\n", atomic_read(&dquot->dq_count));
#endif
spin_lock(&dq_list_lock);
list_add(&dquot->dq_free, tofree_head); /* As dquot must have currently users it can't be on the free list... */
spin_unlock(&dq_list_lock);
return 1;
}
else
dqput(dquot); /* We have guaranteed we won't block */
}
return 0;
}
/* Free list of dquots - called from inode.c */
/* dquots are removed from inodes, no new references can be got so we are the only ones holding reference */
static void put_dquot_list(struct list_head *tofree_head)
{
struct list_head *act_head;
struct dquot *dquot;
act_head = tofree_head->next;
/* So now we have dquots on the list... Just free them */
while (act_head != tofree_head) {
dquot = list_entry(act_head, struct dquot, dq_free);
act_head = act_head->next;
list_del_init(&dquot->dq_free); /* Remove dquot from the list so we won't have problems... */
dqput(dquot);
}
}
static void remove_dquot_ref(struct super_block *sb, int type,
struct list_head *tofree_head)
{
struct inode *inode;
spin_lock(&inode_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
if (!IS_NOQUOTA(inode))
remove_inode_dquot_ref(inode, type, tofree_head);
}
spin_unlock(&inode_lock);
}
/* Gather all references from inodes and drop them */
static void drop_dquot_ref(struct super_block *sb, int type)
{
LIST_HEAD(tofree_head);
if (sb->dq_op) {
down_write(&sb_dqopt(sb)->dqptr_sem);
remove_dquot_ref(sb, type, &tofree_head);
up_write(&sb_dqopt(sb)->dqptr_sem);
put_dquot_list(&tofree_head);
}
}
static inline void dquot_incr_inodes(struct dquot *dquot, qsize_t number)
{
dquot->dq_dqb.dqb_curinodes += number;
}
static inline void dquot_incr_space(struct dquot *dquot, qsize_t number)
{
dquot->dq_dqb.dqb_curspace += number;
}
static inline void dquot_decr_inodes(struct dquot *dquot, qsize_t number)
{
if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NEGATIVE_USAGE ||
dquot->dq_dqb.dqb_curinodes >= number)
dquot->dq_dqb.dqb_curinodes -= number;
else
dquot->dq_dqb.dqb_curinodes = 0;
if (dquot->dq_dqb.dqb_curinodes <= dquot->dq_dqb.dqb_isoftlimit)
dquot->dq_dqb.dqb_itime = (time_t) 0;
clear_bit(DQ_INODES_B, &dquot->dq_flags);
}
static inline void dquot_decr_space(struct dquot *dquot, qsize_t number)
{
if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NEGATIVE_USAGE ||
dquot->dq_dqb.dqb_curspace >= number)
dquot->dq_dqb.dqb_curspace -= number;
else
dquot->dq_dqb.dqb_curspace = 0;
if (dquot->dq_dqb.dqb_curspace <= dquot->dq_dqb.dqb_bsoftlimit)
dquot->dq_dqb.dqb_btime = (time_t) 0;
clear_bit(DQ_BLKS_B, &dquot->dq_flags);
}
static int warning_issued(struct dquot *dquot, const int warntype)
{
int flag = (warntype == QUOTA_NL_BHARDWARN ||
warntype == QUOTA_NL_BSOFTLONGWARN) ? DQ_BLKS_B :
((warntype == QUOTA_NL_IHARDWARN ||
warntype == QUOTA_NL_ISOFTLONGWARN) ? DQ_INODES_B : 0);
if (!flag)
return 0;
return test_and_set_bit(flag, &dquot->dq_flags);
}
#ifdef CONFIG_PRINT_QUOTA_WARNING
static int flag_print_warnings = 1;
static inline int need_print_warning(struct dquot *dquot)
{
if (!flag_print_warnings)
return 0;
switch (dquot->dq_type) {
case USRQUOTA:
return current_fsuid() == dquot->dq_id;
case GRPQUOTA:
return in_group_p(dquot->dq_id);
}
return 0;
}
/* Print warning to user which exceeded quota */
static void print_warning(struct dquot *dquot, const int warntype)
{
char *msg = NULL;
struct tty_struct *tty;
if (warntype == QUOTA_NL_IHARDBELOW ||
warntype == QUOTA_NL_ISOFTBELOW ||
warntype == QUOTA_NL_BHARDBELOW ||
warntype == QUOTA_NL_BSOFTBELOW || !need_print_warning(dquot))
return;
tty = get_current_tty();
if (!tty)
return;
tty_write_message(tty, dquot->dq_sb->s_id);
if (warntype == QUOTA_NL_ISOFTWARN || warntype == QUOTA_NL_BSOFTWARN)
tty_write_message(tty, ": warning, ");
else
tty_write_message(tty, ": write failed, ");
tty_write_message(tty, quotatypes[dquot->dq_type]);
switch (warntype) {
case QUOTA_NL_IHARDWARN:
msg = " file limit reached.\r\n";
break;
case QUOTA_NL_ISOFTLONGWARN:
msg = " file quota exceeded too long.\r\n";
break;
case QUOTA_NL_ISOFTWARN:
msg = " file quota exceeded.\r\n";
break;
case QUOTA_NL_BHARDWARN:
msg = " block limit reached.\r\n";
break;
case QUOTA_NL_BSOFTLONGWARN:
msg = " block quota exceeded too long.\r\n";
break;
case QUOTA_NL_BSOFTWARN:
msg = " block quota exceeded.\r\n";
break;
}
tty_write_message(tty, msg);
tty_kref_put(tty);
}
#endif