-
Notifications
You must be signed in to change notification settings - Fork 263
/
plain_store.c
744 lines (619 loc) · 17.6 KB
/
plain_store.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
/*
* Copyright (C) 2012 Nippon Telegraph and Telephone Corporation.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <libgen.h>
#include <linux/falloc.h>
#include "sheep_priv.h"
#ifndef FALLOC_FL_PUNCH_HOLE
#define FALLOC_FL_PUNCH_HOLE 0x02
#endif
#define sector_algined(x) ({ ((x) & (SECTOR_SIZE - 1)) == 0; })
static inline bool iocb_is_aligned(const struct siocb *iocb)
{
return sector_algined(iocb->offset) && sector_algined(iocb->length);
}
static int prepare_iocb(uint64_t oid, const struct siocb *iocb, bool create)
{
int flags = O_DSYNC | O_RDWR;
if (uatomic_is_true(&sys->use_journal) || sys->nosync == true)
flags &= ~O_DSYNC;
if (sys->backend_dio && iocb_is_aligned(iocb)) {
if (!is_aligned_to_pagesize(iocb->buf))
panic("Memory isn't aligned to pagesize %p", iocb->buf);
flags |= O_DIRECT;
}
if (create)
flags |= O_CREAT | O_EXCL;
return flags;
}
int get_store_path(uint64_t oid, uint8_t ec_index, char *path)
{
if (is_erasure_oid(oid)) {
if (unlikely(ec_index >= SD_MAX_COPIES))
panic("invalid ec_index %d", ec_index);
return snprintf(path, PATH_MAX, "%s/%016"PRIx64"_%d",
md_get_object_dir(oid), oid, ec_index);
}
return snprintf(path, PATH_MAX, "%s/%016" PRIx64,
md_get_object_dir(oid), oid);
}
static int get_store_tmp_path(uint64_t oid, uint8_t ec_index, char *path)
{
if (is_erasure_oid(oid)) {
if (unlikely(ec_index >= SD_MAX_COPIES))
panic("invalid ec_index %d", ec_index);
return snprintf(path, PATH_MAX, "%s/%016"PRIx64"_%d.tmp",
md_get_object_dir(oid), oid, ec_index);
}
return snprintf(path, PATH_MAX, "%s/%016" PRIx64".tmp",
md_get_object_dir(oid), oid);
}
static int get_store_stale_path(uint64_t oid, uint32_t epoch, uint8_t ec_index,
char *path)
{
return md_get_stale_path(oid, epoch, ec_index, path);
}
/*
* Check if oid is in this nodes (if oid is in the wrong place, it will be moved
* to the correct one after this call in a MD setup.
*/
bool default_exist(uint64_t oid, uint8_t ec_index)
{
return md_exist(oid, ec_index);
}
static int err_to_sderr(const char *path, uint64_t oid, int err)
{
struct stat s;
char p[PATH_MAX], *dir;
/* Use a temporary buffer since dirname() may modify its argument. */
pstrcpy(p, sizeof(p), path);
dir = dirname(p);
sd_debug("%s", path);
switch (err) {
case ENOENT:
if (stat(dir, &s) < 0) {
sd_err("%s corrupted", dir);
return md_handle_eio(dir);
}
sd_debug("object %016" PRIx64 " not found locally", oid);
return SD_RES_NO_OBJ;
case ENOSPC:
/* TODO: stop automatic recovery */
sd_err("diskfull, oid=%"PRIx64, oid);
return SD_RES_NO_SPACE;
case EMFILE:
case ENFILE:
case EINTR:
case EAGAIN:
case EEXIST:
sd_err("%m, oid=%"PRIx64, oid);
/* make gateway try again */
return SD_RES_NETWORK_ERROR;
default:
sd_err("oid=%"PRIx64", %m", oid);
return md_handle_eio(dir);
}
}
static int discard(int fd, uint64_t start, uint32_t end)
{
int ret = xfallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
start, end - start);
if (ret < 0) {
if (errno == ENOSYS || errno == EOPNOTSUPP)
sd_info("FALLOC_FL_PUNCH_HOLE is not supported "
"on this filesystem");
else
sd_err("failed to discard object, %m");
}
return ret;
}
/* Trim zero blocks of the beginning and end of the object. */
static int default_trim(int fd, uint64_t oid, const struct siocb *iocb,
uint64_t *poffset, uint32_t *plen)
{
trim_zero_blocks(iocb->buf, poffset, plen);
if (iocb->offset < *poffset) {
sd_debug("discard between %d, %ld, %" PRIx64, iocb->offset,
*poffset, oid);
if (discard(fd, iocb->offset, *poffset) < 0)
return -1;
}
if (*poffset + *plen < iocb->offset + iocb->length) {
uint64_t end = iocb->offset + iocb->length;
if (end == get_objsize(oid))
/* This is necessary to punch the last block */
end = round_up(end, BLOCK_SIZE);
sd_debug("discard between %ld, %ld, %" PRIx64, *poffset + *plen,
end, oid);
if (discard(fd, *poffset + *plen, end) < 0)
return -1;
}
return 0;
}
int default_write(uint64_t oid, const struct siocb *iocb)
{
int flags = prepare_iocb(oid, iocb, false), fd,
ret = SD_RES_SUCCESS;
char path[PATH_MAX];
ssize_t size;
uint32_t len = iocb->length;
uint64_t offset = iocb->offset;
static bool trim_is_supported = true;
if (iocb->epoch < sys_epoch()) {
sd_debug("%"PRIu32" sys %"PRIu32, iocb->epoch, sys_epoch());
return SD_RES_OLD_NODE_VER;
}
if (uatomic_is_true(&sys->use_journal) &&
unlikely(journal_write_store(oid, iocb->buf, iocb->length,
iocb->offset, false))
!= SD_RES_SUCCESS) {
sd_err("turn off journaling");
uatomic_set_false(&sys->use_journal);
flags |= O_DSYNC;
sync();
}
get_store_path(oid, iocb->ec_index, path);
/*
* Make sure oid is in the right place because oid might be misplaced
* in a wrong place, due to 'shutdown/restart with less/more disks' or
* any bugs. We need call err_to_sderr() to return EIO if disk is broken
*/
if (!default_exist(oid, iocb->ec_index))
return err_to_sderr(path, oid, ENOENT);
fd = open(path, flags, sd_def_fmode);
if (unlikely(fd < 0))
return err_to_sderr(path, oid, errno);
if (trim_is_supported && is_sparse_object(oid)) {
if (default_trim(fd, oid, iocb, &offset, &len) < 0) {
trim_is_supported = false;
offset = iocb->offset;
len = iocb->length;
}
}
size = xpwrite(fd, iocb->buf, len, offset);
if (unlikely(size != len)) {
sd_err("failed to write object %"PRIx64", path=%s, offset=%"
PRId32", size=%"PRId32", result=%zd, %m", oid, path,
iocb->offset, iocb->length, size);
ret = err_to_sderr(path, oid, errno);
goto out;
}
out:
close(fd);
return ret;
}
static int make_stale_dir(const char *path)
{
char p[PATH_MAX];
snprintf(p, PATH_MAX, "%s/.stale", path);
if (xmkdir(p, sd_def_dmode) < 0) {
sd_err("%s failed, %m", p);
return SD_RES_EIO;
}
return SD_RES_SUCCESS;
}
static int purge_dir(const char *path)
{
if (purge_directory(path) < 0)
return SD_RES_EIO;
return SD_RES_SUCCESS;
}
static int purge_stale_dir(const char *path)
{
char p[PATH_MAX];
snprintf(p, PATH_MAX, "%s/.stale", path);
return purge_dir(p);
}
int default_cleanup(void)
{
int ret;
ret = for_each_obj_path(purge_stale_dir);
if (ret != SD_RES_SUCCESS)
return ret;
return SD_RES_SUCCESS;
}
static int init_vdi_state(uint64_t oid, const char *wd, uint32_t epoch)
{
int ret;
struct sd_inode *inode = xzalloc(SD_INODE_HEADER_SIZE);
struct siocb iocb = {
.epoch = epoch,
.buf = inode,
.length = SD_INODE_HEADER_SIZE,
};
ret = default_read(oid, &iocb);
if (ret != SD_RES_SUCCESS) {
sd_err("failed to read inode header %" PRIx64 " %" PRId32
"wat %s", oid, epoch, wd);
goto out;
}
add_vdi_state(oid_to_vid(oid), inode->nr_copies,
vdi_is_snapshot(inode), inode->copy_policy);
atomic_set_bit(oid_to_vid(oid), sys->vdi_inuse);
ret = SD_RES_SUCCESS;
out:
free(inode);
return ret;
}
static int init_objlist_and_vdi_bitmap(uint64_t oid, const char *wd,
uint32_t epoch, uint8_t ec_index,
struct vnode_info *vinfo,
void *arg)
{
int ret;
objlist_cache_insert(oid);
if (is_vdi_obj(oid)) {
sd_debug("found the VDI object %" PRIx64" epoch %"PRIu32
" at %s", oid, epoch, wd);
ret = init_vdi_state(oid, wd, epoch);
if (ret != SD_RES_SUCCESS)
return ret;
}
return SD_RES_SUCCESS;
}
int default_init(void)
{
int ret;
sd_debug("use plain store driver");
ret = for_each_obj_path(make_stale_dir);
if (ret != SD_RES_SUCCESS)
return ret;
for_each_object_in_stale(init_objlist_and_vdi_bitmap, NULL);
return for_each_object_in_wd(init_objlist_and_vdi_bitmap, true, NULL);
}
static int default_read_from_path(uint64_t oid, const char *path,
const struct siocb *iocb)
{
int flags = prepare_iocb(oid, iocb, false), fd,
ret = SD_RES_SUCCESS;
ssize_t size;
/*
* Make sure oid is in the right place because oid might be misplaced
* in a wrong place, due to 'shutdown/restart with less disks' or any
* bugs. We need call err_to_sderr() to return EIO if disk is broken.
*
* For stale path, get_store_stale_path already does default_exist job.
*/
if (!is_stale_path(path) && !default_exist(oid, iocb->ec_index))
return err_to_sderr(path, oid, ENOENT);
fd = open(path, flags);
if (fd < 0)
return err_to_sderr(path, oid, errno);
size = xpread(fd, iocb->buf, iocb->length, iocb->offset);
if (size < 0) {
sd_err("failed to read object %"PRIx64", path=%s, offset=%"
PRId32", size=%"PRId32", result=%zd, %m", oid, path,
iocb->offset, iocb->length, size);
ret = err_to_sderr(path, oid, errno);
}
close(fd);
return ret;
}
int default_read(uint64_t oid, const struct siocb *iocb)
{
int ret;
char path[PATH_MAX];
get_store_path(oid, iocb->ec_index, path);
ret = default_read_from_path(oid, path, iocb);
/*
* If the request is againt the older epoch, try to read from
* the stale directory
*/
if (ret == SD_RES_NO_OBJ && iocb->epoch > 0 &&
iocb->epoch < sys_epoch()) {
get_store_stale_path(oid, iocb->epoch, iocb->ec_index, path);
ret = default_read_from_path(oid, path, iocb);
}
return ret;
}
/* Preallocate the whole object to get a better filesystem layout. */
int prealloc(int fd, uint32_t size)
{
int ret = xfallocate(fd, 0, 0, size);
if (ret < 0) {
if (errno != ENOSYS && errno != EOPNOTSUPP) {
sd_err("failed to preallocate space, %m");
return ret;
}
return xftruncate(fd, size);
}
return 0;
}
size_t get_store_objsize(uint64_t oid)
{
if (is_erasure_oid(oid)) {
uint8_t policy = get_vdi_copy_policy(oid_to_vid(oid));
int d;
ec_policy_to_dp(policy, &d, NULL);
return SD_DATA_OBJ_SIZE / d;
}
return get_objsize(oid);
}
int default_create_and_write(uint64_t oid, const struct siocb *iocb)
{
char path[PATH_MAX], tmp_path[PATH_MAX];
int flags = prepare_iocb(oid, iocb, true);
int ret, fd;
uint32_t len = iocb->length;
size_t obj_size;
uint64_t offset = iocb->offset;
sd_debug("%"PRIx64, oid);
get_store_path(oid, iocb->ec_index, path);
get_store_tmp_path(oid, iocb->ec_index, tmp_path);
if (uatomic_is_true(&sys->use_journal) &&
journal_write_store(oid, iocb->buf, iocb->length,
iocb->offset, true)
!= SD_RES_SUCCESS) {
sd_err("turn off journaling");
uatomic_set_false(&sys->use_journal);
flags |= O_DSYNC;
sync();
}
fd = open(tmp_path, flags, sd_def_fmode);
if (fd < 0) {
if (errno == EEXIST) {
/*
* This happens if node membership changes during object
* creation; while gateway retries a CREATE request,
* recovery process could also recover the object at the
* same time. They should try to write the same date,
* so it is okay to simply return success here.
*/
sd_debug("%s exists", tmp_path);
return SD_RES_SUCCESS;
}
sd_err("failed to open %s: %m", tmp_path);
return err_to_sderr(path, oid, errno);
}
obj_size = get_store_objsize(oid);
trim_zero_blocks(iocb->buf, &offset, &len);
if (offset != 0 || len != get_objsize(oid)) {
if (is_sparse_object(oid))
ret = xftruncate(fd, obj_size);
else
ret = prealloc(fd, obj_size);
if (ret < 0) {
ret = err_to_sderr(path, oid, errno);
goto out;
}
}
ret = xpwrite(fd, iocb->buf, len, offset);
if (ret != len) {
sd_err("failed to write object. %m");
ret = err_to_sderr(path, oid, errno);
goto out;
}
ret = rename(tmp_path, path);
if (ret < 0) {
sd_err("failed to rename %s to %s: %m", tmp_path, path);
ret = err_to_sderr(path, oid, errno);
goto out;
}
ret = SD_RES_SUCCESS;
objlist_cache_insert(oid);
out:
if (ret != SD_RES_SUCCESS)
unlink(tmp_path);
close(fd);
return ret;
}
int default_link(uint64_t oid, uint32_t tgt_epoch)
{
char path[PATH_MAX], stale_path[PATH_MAX];
sd_debug("try link %"PRIx64" from snapshot with epoch %d", oid,
tgt_epoch);
snprintf(path, PATH_MAX, "%s/%016"PRIx64, md_get_object_dir(oid), oid);
get_store_stale_path(oid, tgt_epoch, 0, stale_path);
if (link(stale_path, path) < 0) {
/*
* Recovery thread and main thread might try to recover the
* same object and we might get EEXIST in such case.
*/
if (errno == EEXIST)
goto out;
sd_debug("failed to link from %s to %s, %m", stale_path, path);
return err_to_sderr(path, oid, errno);
}
out:
return SD_RES_SUCCESS;
}
/*
* For replicated object, if any of the replica belongs to this node, we
* consider it not stale.
*
* For erasured object, since every copy is unique and if it migrates to other
* node(index gets changed even it has some other copy belongs to it) because
* of hash ring changes, we consider it stale.
*/
static bool oid_stale(uint64_t oid, int ec_index, struct vnode_info *vinfo)
{
uint32_t i, nr_copies;
const struct sd_vnode *v;
bool ret = true;
const struct sd_vnode *obj_vnodes[SD_MAX_COPIES];
nr_copies = get_obj_copy_number(oid, vinfo->nr_zones);
oid_to_vnodes(oid, &vinfo->vroot, nr_copies, obj_vnodes);
for (i = 0; i < nr_copies; i++) {
v = obj_vnodes[i];
if (vnode_is_local(v)) {
if (ec_index < SD_MAX_COPIES) {
if (i == ec_index)
ret = false;
} else {
ret = false;
}
break;
}
}
return ret;
}
static int move_object_to_stale_dir(uint64_t oid, const char *wd,
uint32_t epoch, uint8_t ec_index,
struct vnode_info *vinfo, void *arg)
{
char path[PATH_MAX], stale_path[PATH_MAX];
uint32_t tgt_epoch = *(uint32_t *)arg;
/* ec_index from md.c is reliable so we can directly use it */
if (ec_index < SD_MAX_COPIES) {
snprintf(path, PATH_MAX, "%s/%016"PRIx64"_%d",
md_get_object_dir(oid), oid, ec_index);
snprintf(stale_path, PATH_MAX,
"%s/.stale/%016"PRIx64"_%d.%"PRIu32,
md_get_object_dir(oid), oid, ec_index, tgt_epoch);
} else {
snprintf(path, PATH_MAX, "%s/%016" PRIx64,
md_get_object_dir(oid), oid);
snprintf(stale_path, PATH_MAX, "%s/.stale/%016"PRIx64".%"PRIu32,
md_get_object_dir(oid), oid, tgt_epoch);
}
if (unlikely(rename(path, stale_path)) < 0) {
sd_err("failed to move stale object %" PRIX64 " to %s, %m", oid,
path);
return SD_RES_EIO;
}
sd_debug("moved object %"PRIx64, oid);
return SD_RES_SUCCESS;
}
static int check_stale_objects(uint64_t oid, const char *wd, uint32_t epoch,
uint8_t ec_index, struct vnode_info *vinfo,
void *arg)
{
if (oid_stale(oid, ec_index, vinfo))
return move_object_to_stale_dir(oid, wd, 0, ec_index,
NULL, arg);
return SD_RES_SUCCESS;
}
int default_update_epoch(uint32_t epoch)
{
assert(epoch);
return for_each_object_in_wd(check_stale_objects, false, &epoch);
}
int default_format(void)
{
unsigned ret;
sd_debug("try get a clean store");
ret = for_each_obj_path(purge_dir);
if (ret != SD_RES_SUCCESS)
return ret;
if (sys->enable_object_cache)
object_cache_format();
return SD_RES_SUCCESS;
}
int default_remove_object(uint64_t oid, uint8_t ec_index)
{
char path[PATH_MAX];
if (uatomic_is_true(&sys->use_journal))
journal_remove_object(oid);
get_store_path(oid, ec_index, path);
if (unlink(path) < 0) {
if (errno == ENOENT)
return SD_RES_NO_OBJ;
sd_err("failed, %s, %m", path);
return SD_RES_EIO;
}
return SD_RES_SUCCESS;
}
#define SHA1NAME "user.obj.sha1"
static int get_object_sha1(const char *path, uint8_t *sha1)
{
if (getxattr(path, SHA1NAME, sha1, SHA1_DIGEST_SIZE)
!= SHA1_DIGEST_SIZE) {
if (errno == ENODATA)
sd_debug("sha1 is not cached yet, %s", path);
else
sd_err("fail to get xattr, %s", path);
return -1;
}
return 0;
}
static int set_object_sha1(const char *path, const uint8_t *sha1)
{
int ret;
ret = setxattr(path, SHA1NAME, sha1, SHA1_DIGEST_SIZE, 0);
if (ret < 0)
sd_err("fail to set sha1, %s", path);
return ret;
}
static int get_object_path(uint64_t oid, uint32_t epoch, char *path,
size_t size)
{
if (default_exist(oid, 0)) {
snprintf(path, PATH_MAX, "%s/%016"PRIx64,
md_get_object_dir(oid), oid);
} else {
get_store_stale_path(oid, epoch, 0, path);
if (access(path, F_OK) < 0) {
if (errno == ENOENT)
return SD_RES_NO_OBJ;
return SD_RES_EIO;
}
}
return SD_RES_SUCCESS;
}
int default_get_hash(uint64_t oid, uint32_t epoch, uint8_t *sha1)
{
int ret;
void *buf;
struct siocb iocb = {};
uint32_t length;
bool is_readonly_obj = oid_is_readonly(oid);
char path[PATH_MAX];
ret = get_object_path(oid, epoch, path, sizeof(path));
if (ret != SD_RES_SUCCESS)
return ret;
if (is_readonly_obj) {
if (get_object_sha1(path, sha1) == 0) {
sd_debug("use cached sha1 digest %s",
sha1_to_hex(sha1));
return SD_RES_SUCCESS;
}
}
length = get_store_objsize(oid);
buf = valloc(length);
if (buf == NULL)
return SD_RES_NO_MEM;
iocb.epoch = epoch;
iocb.buf = buf;
iocb.length = length;
ret = default_read_from_path(oid, path, &iocb);
if (ret != SD_RES_SUCCESS) {
free(buf);
return ret;
}
get_buffer_sha1(buf, length, sha1);
free(buf);
sd_debug("the message digest of %"PRIx64" at epoch %d is %s", oid,
epoch, sha1_to_hex(sha1));
if (is_readonly_obj)
set_object_sha1(path, sha1);
return ret;
}
int default_purge_obj(void)
{
uint32_t tgt_epoch = get_latest_epoch();
return for_each_object_in_wd(move_object_to_stale_dir, true,
&tgt_epoch);
}
static struct store_driver plain_store = {
.name = "plain",
.init = default_init,
.exist = default_exist,
.create_and_write = default_create_and_write,
.write = default_write,
.read = default_read,
.link = default_link,
.update_epoch = default_update_epoch,
.cleanup = default_cleanup,
.format = default_format,
.remove_object = default_remove_object,
.get_hash = default_get_hash,
.purge_obj = default_purge_obj,
};
add_store_driver(plain_store);