1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
25 */
26
27 #include <sys/zfs_context.h>
28 #include <sys/spa.h>
29 #include <sys/spa_impl.h>
30 #include <sys/zio.h>
31 #include <sys/ddt.h>
32 #include <sys/zap.h>
33 #include <sys/dmu_tx.h>
34 #include <sys/arc.h>
35 #include <sys/dsl_pool.h>
36 #include <sys/zio_checksum.h>
37 #include <sys/zio_compress.h>
38 #include <sys/dsl_scan.h>
39
40 /*
41 * Enable/disable prefetching of dedup-ed blocks which are going to be freed.
42 */
43 int zfs_dedup_prefetch = 1;
44
45 SYSCTL_DECL(_vfs_zfs);
46 SYSCTL_NODE(_vfs_zfs, OID_AUTO, dedup, CTLFLAG_RW, 0, "ZFS DEDUP");
47 SYSCTL_INT(_vfs_zfs_dedup, OID_AUTO, prefetch, CTLFLAG_RWTUN, &zfs_dedup_prefetch,
48 0, "Enable/disable prefetching of dedup-ed blocks which are going to be freed");
49
50 static const ddt_ops_t *ddt_ops[DDT_TYPES] = {
51 &ddt_zap_ops,
52 };
53
54 static const char *ddt_class_name[DDT_CLASSES] = {
55 "ditto",
56 "duplicate",
57 "unique",
58 };
59
60 static void
ddt_object_create(ddt_t * ddt,enum ddt_type type,enum ddt_class class,dmu_tx_t * tx)61 ddt_object_create(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
62 dmu_tx_t *tx)
63 {
64 spa_t *spa = ddt->ddt_spa;
65 objset_t *os = ddt->ddt_os;
66 uint64_t *objectp = &ddt->ddt_object[type][class];
67 boolean_t prehash = zio_checksum_table[ddt->ddt_checksum].ci_flags &
68 ZCHECKSUM_FLAG_DEDUP;
69 char name[DDT_NAMELEN];
70
71 ddt_object_name(ddt, type, class, name);
72
73 ASSERT(*objectp == 0);
74 VERIFY(ddt_ops[type]->ddt_op_create(os, objectp, tx, prehash) == 0);
75 ASSERT(*objectp != 0);
76
77 VERIFY(zap_add(os, DMU_POOL_DIRECTORY_OBJECT, name,
78 sizeof (uint64_t), 1, objectp, tx) == 0);
79
80 VERIFY(zap_add(os, spa->spa_ddt_stat_object, name,
81 sizeof (uint64_t), sizeof (ddt_histogram_t) / sizeof (uint64_t),
82 &ddt->ddt_histogram[type][class], tx) == 0);
83 }
84
85 static void
ddt_object_destroy(ddt_t * ddt,enum ddt_type type,enum ddt_class class,dmu_tx_t * tx)86 ddt_object_destroy(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
87 dmu_tx_t *tx)
88 {
89 spa_t *spa = ddt->ddt_spa;
90 objset_t *os = ddt->ddt_os;
91 uint64_t *objectp = &ddt->ddt_object[type][class];
92 uint64_t count;
93 char name[DDT_NAMELEN];
94
95 ddt_object_name(ddt, type, class, name);
96
97 ASSERT(*objectp != 0);
98 VERIFY(ddt_object_count(ddt, type, class, &count) == 0 && count == 0);
99 ASSERT(ddt_histogram_empty(&ddt->ddt_histogram[type][class]));
100 VERIFY(zap_remove(os, DMU_POOL_DIRECTORY_OBJECT, name, tx) == 0);
101 VERIFY(zap_remove(os, spa->spa_ddt_stat_object, name, tx) == 0);
102 VERIFY(ddt_ops[type]->ddt_op_destroy(os, *objectp, tx) == 0);
103 bzero(&ddt->ddt_object_stats[type][class], sizeof (ddt_object_t));
104
105 *objectp = 0;
106 }
107
108 static int
ddt_object_load(ddt_t * ddt,enum ddt_type type,enum ddt_class class)109 ddt_object_load(ddt_t *ddt, enum ddt_type type, enum ddt_class class)
110 {
111 ddt_object_t *ddo = &ddt->ddt_object_stats[type][class];
112 dmu_object_info_t doi;
113 uint64_t count;
114 char name[DDT_NAMELEN];
115 int error;
116
117 ddt_object_name(ddt, type, class, name);
118
119 error = zap_lookup(ddt->ddt_os, DMU_POOL_DIRECTORY_OBJECT, name,
120 sizeof (uint64_t), 1, &ddt->ddt_object[type][class]);
121
122 if (error != 0)
123 return (error);
124
125 VERIFY0(zap_lookup(ddt->ddt_os, ddt->ddt_spa->spa_ddt_stat_object, name,
126 sizeof (uint64_t), sizeof (ddt_histogram_t) / sizeof (uint64_t),
127 &ddt->ddt_histogram[type][class]));
128
129 /*
130 * Seed the cached statistics.
131 */
132 VERIFY(ddt_object_info(ddt, type, class, &doi) == 0);
133
134 error = ddt_object_count(ddt, type, class, &count);
135 if (error)
136 return error;
137
138 ddo->ddo_count = count;
139 ddo->ddo_dspace = doi.doi_physical_blocks_512 << 9;
140 ddo->ddo_mspace = doi.doi_fill_count * doi.doi_data_block_size;
141
142 return (0);
143 }
144
145 static void
ddt_object_sync(ddt_t * ddt,enum ddt_type type,enum ddt_class class,dmu_tx_t * tx)146 ddt_object_sync(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
147 dmu_tx_t *tx)
148 {
149 ddt_object_t *ddo = &ddt->ddt_object_stats[type][class];
150 dmu_object_info_t doi;
151 uint64_t count;
152 char name[DDT_NAMELEN];
153
154 ddt_object_name(ddt, type, class, name);
155
156 VERIFY(zap_update(ddt->ddt_os, ddt->ddt_spa->spa_ddt_stat_object, name,
157 sizeof (uint64_t), sizeof (ddt_histogram_t) / sizeof (uint64_t),
158 &ddt->ddt_histogram[type][class], tx) == 0);
159
160 /*
161 * Cache DDT statistics; this is the only time they'll change.
162 */
163 VERIFY(ddt_object_info(ddt, type, class, &doi) == 0);
164 VERIFY(ddt_object_count(ddt, type, class, &count) == 0);
165
166 ddo->ddo_count = count;
167 ddo->ddo_dspace = doi.doi_physical_blocks_512 << 9;
168 ddo->ddo_mspace = doi.doi_fill_count * doi.doi_data_block_size;
169 }
170
171 static int
ddt_object_lookup(ddt_t * ddt,enum ddt_type type,enum ddt_class class,ddt_entry_t * dde)172 ddt_object_lookup(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
173 ddt_entry_t *dde)
174 {
175 if (!ddt_object_exists(ddt, type, class))
176 return (SET_ERROR(ENOENT));
177
178 return (ddt_ops[type]->ddt_op_lookup(ddt->ddt_os,
179 ddt->ddt_object[type][class], dde));
180 }
181
182 static void
ddt_object_prefetch(ddt_t * ddt,enum ddt_type type,enum ddt_class class,ddt_entry_t * dde)183 ddt_object_prefetch(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
184 ddt_entry_t *dde)
185 {
186 if (!ddt_object_exists(ddt, type, class))
187 return;
188
189 ddt_ops[type]->ddt_op_prefetch(ddt->ddt_os,
190 ddt->ddt_object[type][class], dde);
191 }
192
193 int
ddt_object_update(ddt_t * ddt,enum ddt_type type,enum ddt_class class,ddt_entry_t * dde,dmu_tx_t * tx)194 ddt_object_update(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
195 ddt_entry_t *dde, dmu_tx_t *tx)
196 {
197 ASSERT(ddt_object_exists(ddt, type, class));
198
199 return (ddt_ops[type]->ddt_op_update(ddt->ddt_os,
200 ddt->ddt_object[type][class], dde, tx));
201 }
202
203 static int
ddt_object_remove(ddt_t * ddt,enum ddt_type type,enum ddt_class class,ddt_entry_t * dde,dmu_tx_t * tx)204 ddt_object_remove(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
205 ddt_entry_t *dde, dmu_tx_t *tx)
206 {
207 ASSERT(ddt_object_exists(ddt, type, class));
208
209 return (ddt_ops[type]->ddt_op_remove(ddt->ddt_os,
210 ddt->ddt_object[type][class], dde, tx));
211 }
212
213 int
ddt_object_walk(ddt_t * ddt,enum ddt_type type,enum ddt_class class,uint64_t * walk,ddt_entry_t * dde)214 ddt_object_walk(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
215 uint64_t *walk, ddt_entry_t *dde)
216 {
217 ASSERT(ddt_object_exists(ddt, type, class));
218
219 return (ddt_ops[type]->ddt_op_walk(ddt->ddt_os,
220 ddt->ddt_object[type][class], dde, walk));
221 }
222
223 int
ddt_object_count(ddt_t * ddt,enum ddt_type type,enum ddt_class class,uint64_t * count)224 ddt_object_count(ddt_t *ddt, enum ddt_type type, enum ddt_class class, uint64_t *count)
225 {
226 ASSERT(ddt_object_exists(ddt, type, class));
227
228 return (ddt_ops[type]->ddt_op_count(ddt->ddt_os,
229 ddt->ddt_object[type][class], count));
230 }
231
232 int
ddt_object_info(ddt_t * ddt,enum ddt_type type,enum ddt_class class,dmu_object_info_t * doi)233 ddt_object_info(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
234 dmu_object_info_t *doi)
235 {
236 if (!ddt_object_exists(ddt, type, class))
237 return (SET_ERROR(ENOENT));
238
239 return (dmu_object_info(ddt->ddt_os, ddt->ddt_object[type][class],
240 doi));
241 }
242
243 boolean_t
ddt_object_exists(ddt_t * ddt,enum ddt_type type,enum ddt_class class)244 ddt_object_exists(ddt_t *ddt, enum ddt_type type, enum ddt_class class)
245 {
246 return (!!ddt->ddt_object[type][class]);
247 }
248
249 void
ddt_object_name(ddt_t * ddt,enum ddt_type type,enum ddt_class class,char * name)250 ddt_object_name(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
251 char *name)
252 {
253 (void) sprintf(name, DMU_POOL_DDT,
254 zio_checksum_table[ddt->ddt_checksum].ci_name,
255 ddt_ops[type]->ddt_op_name, ddt_class_name[class]);
256 }
257
258 void
ddt_bp_fill(const ddt_phys_t * ddp,blkptr_t * bp,uint64_t txg)259 ddt_bp_fill(const ddt_phys_t *ddp, blkptr_t *bp, uint64_t txg)
260 {
261 ASSERT(txg != 0);
262
263 for (int d = 0; d < SPA_DVAS_PER_BP; d++)
264 bp->blk_dva[d] = ddp->ddp_dva[d];
265 BP_SET_BIRTH(bp, txg, ddp->ddp_phys_birth);
266 }
267
268 void
ddt_bp_create(enum zio_checksum checksum,const ddt_key_t * ddk,const ddt_phys_t * ddp,blkptr_t * bp)269 ddt_bp_create(enum zio_checksum checksum,
270 const ddt_key_t *ddk, const ddt_phys_t *ddp, blkptr_t *bp)
271 {
272 BP_ZERO(bp);
273
274 if (ddp != NULL)
275 ddt_bp_fill(ddp, bp, ddp->ddp_phys_birth);
276
277 bp->blk_cksum = ddk->ddk_cksum;
278 bp->blk_fill = 1;
279
280 BP_SET_LSIZE(bp, DDK_GET_LSIZE(ddk));
281 BP_SET_PSIZE(bp, DDK_GET_PSIZE(ddk));
282 BP_SET_COMPRESS(bp, DDK_GET_COMPRESS(ddk));
283 BP_SET_CHECKSUM(bp, checksum);
284 BP_SET_TYPE(bp, DMU_OT_DEDUP);
285 BP_SET_LEVEL(bp, 0);
286 BP_SET_DEDUP(bp, 0);
287 BP_SET_BYTEORDER(bp, ZFS_HOST_BYTEORDER);
288 }
289
290 void
ddt_key_fill(ddt_key_t * ddk,const blkptr_t * bp)291 ddt_key_fill(ddt_key_t *ddk, const blkptr_t *bp)
292 {
293 ddk->ddk_cksum = bp->blk_cksum;
294 ddk->ddk_prop = 0;
295
296 DDK_SET_LSIZE(ddk, BP_GET_LSIZE(bp));
297 DDK_SET_PSIZE(ddk, BP_GET_PSIZE(bp));
298 DDK_SET_COMPRESS(ddk, BP_GET_COMPRESS(bp));
299 }
300
301 void
ddt_phys_fill(ddt_phys_t * ddp,const blkptr_t * bp)302 ddt_phys_fill(ddt_phys_t *ddp, const blkptr_t *bp)
303 {
304 ASSERT(ddp->ddp_phys_birth == 0);
305
306 for (int d = 0; d < SPA_DVAS_PER_BP; d++)
307 ddp->ddp_dva[d] = bp->blk_dva[d];
308 ddp->ddp_phys_birth = BP_PHYSICAL_BIRTH(bp);
309 }
310
311 void
ddt_phys_clear(ddt_phys_t * ddp)312 ddt_phys_clear(ddt_phys_t *ddp)
313 {
314 bzero(ddp, sizeof (*ddp));
315 }
316
317 void
ddt_phys_addref(ddt_phys_t * ddp)318 ddt_phys_addref(ddt_phys_t *ddp)
319 {
320 ddp->ddp_refcnt++;
321 }
322
323 void
ddt_phys_decref(ddt_phys_t * ddp)324 ddt_phys_decref(ddt_phys_t *ddp)
325 {
326 ASSERT((int64_t)ddp->ddp_refcnt > 0);
327 ddp->ddp_refcnt--;
328 }
329
330 void
ddt_phys_free(ddt_t * ddt,ddt_key_t * ddk,ddt_phys_t * ddp,uint64_t txg)331 ddt_phys_free(ddt_t *ddt, ddt_key_t *ddk, ddt_phys_t *ddp, uint64_t txg)
332 {
333 blkptr_t blk;
334
335 ddt_bp_create(ddt->ddt_checksum, ddk, ddp, &blk);
336 ddt_phys_clear(ddp);
337 zio_free(ddt->ddt_spa, txg, &blk);
338 }
339
340 ddt_phys_t *
ddt_phys_select(const ddt_entry_t * dde,const blkptr_t * bp)341 ddt_phys_select(const ddt_entry_t *dde, const blkptr_t *bp)
342 {
343 ddt_phys_t *ddp = (ddt_phys_t *)dde->dde_phys;
344
345 for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
346 if (DVA_EQUAL(BP_IDENTITY(bp), &ddp->ddp_dva[0]) &&
347 BP_PHYSICAL_BIRTH(bp) == ddp->ddp_phys_birth)
348 return (ddp);
349 }
350 return (NULL);
351 }
352
353 uint64_t
ddt_phys_total_refcnt(const ddt_entry_t * dde)354 ddt_phys_total_refcnt(const ddt_entry_t *dde)
355 {
356 uint64_t refcnt = 0;
357
358 for (int p = DDT_PHYS_SINGLE; p <= DDT_PHYS_TRIPLE; p++)
359 refcnt += dde->dde_phys[p].ddp_refcnt;
360
361 return (refcnt);
362 }
363
364 static void
ddt_stat_generate(ddt_t * ddt,ddt_entry_t * dde,ddt_stat_t * dds)365 ddt_stat_generate(ddt_t *ddt, ddt_entry_t *dde, ddt_stat_t *dds)
366 {
367 spa_t *spa = ddt->ddt_spa;
368 ddt_phys_t *ddp = dde->dde_phys;
369 ddt_key_t *ddk = &dde->dde_key;
370 uint64_t lsize = DDK_GET_LSIZE(ddk);
371 uint64_t psize = DDK_GET_PSIZE(ddk);
372
373 bzero(dds, sizeof (*dds));
374
375 for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
376 uint64_t dsize = 0;
377 uint64_t refcnt = ddp->ddp_refcnt;
378
379 if (ddp->ddp_phys_birth == 0)
380 continue;
381
382 for (int d = 0; d < SPA_DVAS_PER_BP; d++)
383 dsize += dva_get_dsize_sync(spa, &ddp->ddp_dva[d]);
384
385 dds->dds_blocks += 1;
386 dds->dds_lsize += lsize;
387 dds->dds_psize += psize;
388 dds->dds_dsize += dsize;
389
390 dds->dds_ref_blocks += refcnt;
391 dds->dds_ref_lsize += lsize * refcnt;
392 dds->dds_ref_psize += psize * refcnt;
393 dds->dds_ref_dsize += dsize * refcnt;
394 }
395 }
396
397 void
ddt_stat_add(ddt_stat_t * dst,const ddt_stat_t * src,uint64_t neg)398 ddt_stat_add(ddt_stat_t *dst, const ddt_stat_t *src, uint64_t neg)
399 {
400 const uint64_t *s = (const uint64_t *)src;
401 uint64_t *d = (uint64_t *)dst;
402 uint64_t *d_end = (uint64_t *)(dst + 1);
403
404 ASSERT(neg == 0 || neg == -1ULL); /* add or subtract */
405
406 while (d < d_end)
407 *d++ += (*s++ ^ neg) - neg;
408 }
409
410 static void
ddt_stat_update(ddt_t * ddt,ddt_entry_t * dde,uint64_t neg)411 ddt_stat_update(ddt_t *ddt, ddt_entry_t *dde, uint64_t neg)
412 {
413 ddt_stat_t dds;
414 ddt_histogram_t *ddh;
415 int bucket;
416
417 ddt_stat_generate(ddt, dde, &dds);
418
419 bucket = highbit64(dds.dds_ref_blocks) - 1;
420 ASSERT(bucket >= 0);
421
422 ddh = &ddt->ddt_histogram[dde->dde_type][dde->dde_class];
423
424 ddt_stat_add(&ddh->ddh_stat[bucket], &dds, neg);
425 }
426
427 void
ddt_histogram_add(ddt_histogram_t * dst,const ddt_histogram_t * src)428 ddt_histogram_add(ddt_histogram_t *dst, const ddt_histogram_t *src)
429 {
430 for (int h = 0; h < 64; h++)
431 ddt_stat_add(&dst->ddh_stat[h], &src->ddh_stat[h], 0);
432 }
433
434 void
ddt_histogram_stat(ddt_stat_t * dds,const ddt_histogram_t * ddh)435 ddt_histogram_stat(ddt_stat_t *dds, const ddt_histogram_t *ddh)
436 {
437 bzero(dds, sizeof (*dds));
438
439 for (int h = 0; h < 64; h++)
440 ddt_stat_add(dds, &ddh->ddh_stat[h], 0);
441 }
442
443 boolean_t
ddt_histogram_empty(const ddt_histogram_t * ddh)444 ddt_histogram_empty(const ddt_histogram_t *ddh)
445 {
446 const uint64_t *s = (const uint64_t *)ddh;
447 const uint64_t *s_end = (const uint64_t *)(ddh + 1);
448
449 while (s < s_end)
450 if (*s++ != 0)
451 return (B_FALSE);
452
453 return (B_TRUE);
454 }
455
456 void
ddt_get_dedup_object_stats(spa_t * spa,ddt_object_t * ddo_total)457 ddt_get_dedup_object_stats(spa_t *spa, ddt_object_t *ddo_total)
458 {
459 /* Sum the statistics we cached in ddt_object_sync(). */
460 for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
461 ddt_t *ddt = spa->spa_ddt[c];
462 for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
463 for (enum ddt_class class = 0; class < DDT_CLASSES;
464 class++) {
465 ddt_object_t *ddo =
466 &ddt->ddt_object_stats[type][class];
467 ddo_total->ddo_count += ddo->ddo_count;
468 ddo_total->ddo_dspace += ddo->ddo_dspace;
469 ddo_total->ddo_mspace += ddo->ddo_mspace;
470 }
471 }
472 }
473
474 /* ... and compute the averages. */
475 if (ddo_total->ddo_count != 0) {
476 ddo_total->ddo_dspace /= ddo_total->ddo_count;
477 ddo_total->ddo_mspace /= ddo_total->ddo_count;
478 }
479 }
480
481 void
ddt_get_dedup_histogram(spa_t * spa,ddt_histogram_t * ddh)482 ddt_get_dedup_histogram(spa_t *spa, ddt_histogram_t *ddh)
483 {
484 for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
485 ddt_t *ddt = spa->spa_ddt[c];
486 for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
487 for (enum ddt_class class = 0; class < DDT_CLASSES;
488 class++) {
489 ddt_histogram_add(ddh,
490 &ddt->ddt_histogram_cache[type][class]);
491 }
492 }
493 }
494 }
495
496 void
ddt_get_dedup_stats(spa_t * spa,ddt_stat_t * dds_total)497 ddt_get_dedup_stats(spa_t *spa, ddt_stat_t *dds_total)
498 {
499 ddt_histogram_t *ddh_total;
500
501 ddh_total = kmem_zalloc(sizeof (ddt_histogram_t), KM_SLEEP);
502 ddt_get_dedup_histogram(spa, ddh_total);
503 ddt_histogram_stat(dds_total, ddh_total);
504 kmem_free(ddh_total, sizeof (ddt_histogram_t));
505 }
506
507 uint64_t
ddt_get_dedup_dspace(spa_t * spa)508 ddt_get_dedup_dspace(spa_t *spa)
509 {
510 ddt_stat_t dds_total = { 0 };
511
512 ddt_get_dedup_stats(spa, &dds_total);
513 return (dds_total.dds_ref_dsize - dds_total.dds_dsize);
514 }
515
516 uint64_t
ddt_get_pool_dedup_ratio(spa_t * spa)517 ddt_get_pool_dedup_ratio(spa_t *spa)
518 {
519 ddt_stat_t dds_total = { 0 };
520
521 ddt_get_dedup_stats(spa, &dds_total);
522 if (dds_total.dds_dsize == 0)
523 return (100);
524
525 return (dds_total.dds_ref_dsize * 100 / dds_total.dds_dsize);
526 }
527
528 int
ddt_ditto_copies_needed(ddt_t * ddt,ddt_entry_t * dde,ddt_phys_t * ddp_willref)529 ddt_ditto_copies_needed(ddt_t *ddt, ddt_entry_t *dde, ddt_phys_t *ddp_willref)
530 {
531 spa_t *spa = ddt->ddt_spa;
532 uint64_t total_refcnt = 0;
533 uint64_t ditto = spa->spa_dedup_ditto;
534 int total_copies = 0;
535 int desired_copies = 0;
536
537 for (int p = DDT_PHYS_SINGLE; p <= DDT_PHYS_TRIPLE; p++) {
538 ddt_phys_t *ddp = &dde->dde_phys[p];
539 zio_t *zio = dde->dde_lead_zio[p];
540 uint64_t refcnt = ddp->ddp_refcnt; /* committed refs */
541 if (zio != NULL)
542 refcnt += zio->io_parent_count; /* pending refs */
543 if (ddp == ddp_willref)
544 refcnt++; /* caller's ref */
545 if (refcnt != 0) {
546 total_refcnt += refcnt;
547 total_copies += p;
548 }
549 }
550
551 if (ditto == 0 || ditto > UINT32_MAX)
552 ditto = UINT32_MAX;
553
554 if (total_refcnt >= 1)
555 desired_copies++;
556 if (total_refcnt >= ditto)
557 desired_copies++;
558 if (total_refcnt >= ditto * ditto)
559 desired_copies++;
560
561 return (MAX(desired_copies, total_copies) - total_copies);
562 }
563
564 int
ddt_ditto_copies_present(ddt_entry_t * dde)565 ddt_ditto_copies_present(ddt_entry_t *dde)
566 {
567 ddt_phys_t *ddp = &dde->dde_phys[DDT_PHYS_DITTO];
568 dva_t *dva = ddp->ddp_dva;
569 int copies = 0 - DVA_GET_GANG(dva);
570
571 for (int d = 0; d < SPA_DVAS_PER_BP; d++, dva++)
572 if (DVA_IS_VALID(dva))
573 copies++;
574
575 ASSERT(copies >= 0 && copies < SPA_DVAS_PER_BP);
576
577 return (copies);
578 }
579
580 size_t
ddt_compress(void * src,uchar_t * dst,size_t s_len,size_t d_len)581 ddt_compress(void *src, uchar_t *dst, size_t s_len, size_t d_len)
582 {
583 uchar_t *version = dst++;
584 int cpfunc = ZIO_COMPRESS_ZLE;
585 zio_compress_info_t *ci = &zio_compress_table[cpfunc];
586 size_t c_len;
587
588 ASSERT(d_len >= s_len + 1); /* no compression plus version byte */
589
590 c_len = ci->ci_compress(src, dst, s_len, d_len - 1, ci->ci_level);
591
592 if (c_len == s_len) {
593 cpfunc = ZIO_COMPRESS_OFF;
594 bcopy(src, dst, s_len);
595 }
596
597 *version = cpfunc;
598 /* CONSTCOND */
599 if (ZFS_HOST_BYTEORDER)
600 *version |= DDT_COMPRESS_BYTEORDER_MASK;
601
602 return (c_len + 1);
603 }
604
605 void
ddt_decompress(uchar_t * src,void * dst,size_t s_len,size_t d_len)606 ddt_decompress(uchar_t *src, void *dst, size_t s_len, size_t d_len)
607 {
608 uchar_t version = *src++;
609 int cpfunc = version & DDT_COMPRESS_FUNCTION_MASK;
610 zio_compress_info_t *ci = &zio_compress_table[cpfunc];
611
612 if (ci->ci_decompress != NULL)
613 (void) ci->ci_decompress(src, dst, s_len, d_len, ci->ci_level);
614 else
615 bcopy(src, dst, d_len);
616
617 if (((version & DDT_COMPRESS_BYTEORDER_MASK) != 0) !=
618 (ZFS_HOST_BYTEORDER != 0))
619 byteswap_uint64_array(dst, d_len);
620 }
621
622 ddt_t *
ddt_select_by_checksum(spa_t * spa,enum zio_checksum c)623 ddt_select_by_checksum(spa_t *spa, enum zio_checksum c)
624 {
625 return (spa->spa_ddt[c]);
626 }
627
628 ddt_t *
ddt_select(spa_t * spa,const blkptr_t * bp)629 ddt_select(spa_t *spa, const blkptr_t *bp)
630 {
631 return (spa->spa_ddt[BP_GET_CHECKSUM(bp)]);
632 }
633
634 void
ddt_enter(ddt_t * ddt)635 ddt_enter(ddt_t *ddt)
636 {
637 mutex_enter(&ddt->ddt_lock);
638 }
639
640 void
ddt_exit(ddt_t * ddt)641 ddt_exit(ddt_t *ddt)
642 {
643 mutex_exit(&ddt->ddt_lock);
644 }
645
646 static ddt_entry_t *
ddt_alloc(const ddt_key_t * ddk)647 ddt_alloc(const ddt_key_t *ddk)
648 {
649 ddt_entry_t *dde;
650
651 dde = kmem_zalloc(sizeof (ddt_entry_t), KM_SLEEP);
652 cv_init(&dde->dde_cv, NULL, CV_DEFAULT, NULL);
653
654 dde->dde_key = *ddk;
655
656 return (dde);
657 }
658
659 static void
ddt_free(ddt_entry_t * dde)660 ddt_free(ddt_entry_t *dde)
661 {
662 ASSERT(!dde->dde_loading);
663
664 for (int p = 0; p < DDT_PHYS_TYPES; p++)
665 ASSERT(dde->dde_lead_zio[p] == NULL);
666
667 if (dde->dde_repair_data != NULL)
668 zio_buf_free(dde->dde_repair_data,
669 DDK_GET_PSIZE(&dde->dde_key));
670
671 cv_destroy(&dde->dde_cv);
672 kmem_free(dde, sizeof (*dde));
673 }
674
675 void
ddt_remove(ddt_t * ddt,ddt_entry_t * dde)676 ddt_remove(ddt_t *ddt, ddt_entry_t *dde)
677 {
678 ASSERT(MUTEX_HELD(&ddt->ddt_lock));
679
680 avl_remove(&ddt->ddt_tree, dde);
681 ddt_free(dde);
682 }
683
684 ddt_entry_t *
ddt_lookup(ddt_t * ddt,const blkptr_t * bp,boolean_t add)685 ddt_lookup(ddt_t *ddt, const blkptr_t *bp, boolean_t add)
686 {
687 ddt_entry_t *dde, dde_search;
688 enum ddt_type type;
689 enum ddt_class class;
690 avl_index_t where;
691 int error;
692
693 ASSERT(MUTEX_HELD(&ddt->ddt_lock));
694
695 ddt_key_fill(&dde_search.dde_key, bp);
696
697 dde = avl_find(&ddt->ddt_tree, &dde_search, &where);
698 if (dde == NULL) {
699 if (!add)
700 return (NULL);
701 dde = ddt_alloc(&dde_search.dde_key);
702 avl_insert(&ddt->ddt_tree, dde, where);
703 }
704
705 while (dde->dde_loading)
706 cv_wait(&dde->dde_cv, &ddt->ddt_lock);
707
708 if (dde->dde_loaded)
709 return (dde);
710
711 dde->dde_loading = B_TRUE;
712
713 ddt_exit(ddt);
714
715 error = ENOENT;
716
717 for (type = 0; type < DDT_TYPES; type++) {
718 for (class = 0; class < DDT_CLASSES; class++) {
719 error = ddt_object_lookup(ddt, type, class, dde);
720 if (error != ENOENT)
721 break;
722 }
723 if (error != ENOENT)
724 break;
725 }
726
727 ASSERT(error == 0 || error == ENOENT);
728
729 ddt_enter(ddt);
730
731 ASSERT(dde->dde_loaded == B_FALSE);
732 ASSERT(dde->dde_loading == B_TRUE);
733
734 dde->dde_type = type; /* will be DDT_TYPES if no entry found */
735 dde->dde_class = class; /* will be DDT_CLASSES if no entry found */
736 dde->dde_loaded = B_TRUE;
737 dde->dde_loading = B_FALSE;
738
739 if (error == 0)
740 ddt_stat_update(ddt, dde, -1ULL);
741
742 cv_broadcast(&dde->dde_cv);
743
744 return (dde);
745 }
746
747 void
ddt_prefetch(spa_t * spa,const blkptr_t * bp)748 ddt_prefetch(spa_t *spa, const blkptr_t *bp)
749 {
750 ddt_t *ddt;
751 ddt_entry_t dde;
752
753 if (!zfs_dedup_prefetch || bp == NULL || !BP_GET_DEDUP(bp))
754 return;
755
756 /*
757 * We only remove the DDT once all tables are empty and only
758 * prefetch dedup blocks when there are entries in the DDT.
759 * Thus no locking is required as the DDT can't disappear on us.
760 */
761 ddt = ddt_select(spa, bp);
762 ddt_key_fill(&dde.dde_key, bp);
763
764 for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
765 for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
766 ddt_object_prefetch(ddt, type, class, &dde);
767 }
768 }
769 }
770
771 int
ddt_entry_compare(const void * x1,const void * x2)772 ddt_entry_compare(const void *x1, const void *x2)
773 {
774 const ddt_entry_t *dde1 = x1;
775 const ddt_entry_t *dde2 = x2;
776 const uint64_t *u1 = (const uint64_t *)&dde1->dde_key;
777 const uint64_t *u2 = (const uint64_t *)&dde2->dde_key;
778
779 for (int i = 0; i < DDT_KEY_WORDS; i++) {
780 if (u1[i] < u2[i])
781 return (-1);
782 if (u1[i] > u2[i])
783 return (1);
784 }
785
786 return (0);
787 }
788
789 static ddt_t *
ddt_table_alloc(spa_t * spa,enum zio_checksum c)790 ddt_table_alloc(spa_t *spa, enum zio_checksum c)
791 {
792 ddt_t *ddt;
793
794 ddt = kmem_zalloc(sizeof (*ddt), KM_SLEEP);
795
796 mutex_init(&ddt->ddt_lock, NULL, MUTEX_DEFAULT, NULL);
797 avl_create(&ddt->ddt_tree, ddt_entry_compare,
798 sizeof (ddt_entry_t), offsetof(ddt_entry_t, dde_node));
799 avl_create(&ddt->ddt_repair_tree, ddt_entry_compare,
800 sizeof (ddt_entry_t), offsetof(ddt_entry_t, dde_node));
801 ddt->ddt_checksum = c;
802 ddt->ddt_spa = spa;
803 ddt->ddt_os = spa->spa_meta_objset;
804
805 return (ddt);
806 }
807
808 static void
ddt_table_free(ddt_t * ddt)809 ddt_table_free(ddt_t *ddt)
810 {
811 ASSERT(avl_numnodes(&ddt->ddt_tree) == 0);
812 ASSERT(avl_numnodes(&ddt->ddt_repair_tree) == 0);
813 avl_destroy(&ddt->ddt_tree);
814 avl_destroy(&ddt->ddt_repair_tree);
815 mutex_destroy(&ddt->ddt_lock);
816 kmem_free(ddt, sizeof (*ddt));
817 }
818
819 void
ddt_create(spa_t * spa)820 ddt_create(spa_t *spa)
821 {
822 spa->spa_dedup_checksum = ZIO_DEDUPCHECKSUM;
823
824 for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++)
825 spa->spa_ddt[c] = ddt_table_alloc(spa, c);
826 }
827
828 int
ddt_load(spa_t * spa)829 ddt_load(spa_t *spa)
830 {
831 int error;
832
833 ddt_create(spa);
834
835 error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
836 DMU_POOL_DDT_STATS, sizeof (uint64_t), 1,
837 &spa->spa_ddt_stat_object);
838
839 if (error)
840 return (error == ENOENT ? 0 : error);
841
842 for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
843 ddt_t *ddt = spa->spa_ddt[c];
844 for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
845 for (enum ddt_class class = 0; class < DDT_CLASSES;
846 class++) {
847 error = ddt_object_load(ddt, type, class);
848 if (error != 0 && error != ENOENT)
849 return (error);
850 }
851 }
852
853 /*
854 * Seed the cached histograms.
855 */
856 bcopy(ddt->ddt_histogram, &ddt->ddt_histogram_cache,
857 sizeof (ddt->ddt_histogram));
858 }
859
860 return (0);
861 }
862
863 void
ddt_unload(spa_t * spa)864 ddt_unload(spa_t *spa)
865 {
866 for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
867 if (spa->spa_ddt[c]) {
868 ddt_table_free(spa->spa_ddt[c]);
869 spa->spa_ddt[c] = NULL;
870 }
871 }
872 }
873
874 boolean_t
ddt_class_contains(spa_t * spa,enum ddt_class max_class,const blkptr_t * bp)875 ddt_class_contains(spa_t *spa, enum ddt_class max_class, const blkptr_t *bp)
876 {
877 ddt_t *ddt;
878 ddt_entry_t dde;
879
880 if (!BP_GET_DEDUP(bp))
881 return (B_FALSE);
882
883 if (max_class == DDT_CLASS_UNIQUE)
884 return (B_TRUE);
885
886 ddt = spa->spa_ddt[BP_GET_CHECKSUM(bp)];
887
888 ddt_key_fill(&dde.dde_key, bp);
889
890 for (enum ddt_type type = 0; type < DDT_TYPES; type++)
891 for (enum ddt_class class = 0; class <= max_class; class++)
892 if (ddt_object_lookup(ddt, type, class, &dde) == 0)
893 return (B_TRUE);
894
895 return (B_FALSE);
896 }
897
898 ddt_entry_t *
ddt_repair_start(ddt_t * ddt,const blkptr_t * bp)899 ddt_repair_start(ddt_t *ddt, const blkptr_t *bp)
900 {
901 ddt_key_t ddk;
902 ddt_entry_t *dde;
903
904 ddt_key_fill(&ddk, bp);
905
906 dde = ddt_alloc(&ddk);
907
908 for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
909 for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
910 /*
911 * We can only do repair if there are multiple copies
912 * of the block. For anything in the UNIQUE class,
913 * there's definitely only one copy, so don't even try.
914 */
915 if (class != DDT_CLASS_UNIQUE &&
916 ddt_object_lookup(ddt, type, class, dde) == 0)
917 return (dde);
918 }
919 }
920
921 bzero(dde->dde_phys, sizeof (dde->dde_phys));
922
923 return (dde);
924 }
925
926 void
ddt_repair_done(ddt_t * ddt,ddt_entry_t * dde)927 ddt_repair_done(ddt_t *ddt, ddt_entry_t *dde)
928 {
929 avl_index_t where;
930
931 ddt_enter(ddt);
932
933 if (dde->dde_repair_data != NULL && spa_writeable(ddt->ddt_spa) &&
934 avl_find(&ddt->ddt_repair_tree, dde, &where) == NULL)
935 avl_insert(&ddt->ddt_repair_tree, dde, where);
936 else
937 ddt_free(dde);
938
939 ddt_exit(ddt);
940 }
941
942 static void
ddt_repair_entry_done(zio_t * zio)943 ddt_repair_entry_done(zio_t *zio)
944 {
945 ddt_entry_t *rdde = zio->io_private;
946
947 ddt_free(rdde);
948 }
949
950 static void
ddt_repair_entry(ddt_t * ddt,ddt_entry_t * dde,ddt_entry_t * rdde,zio_t * rio)951 ddt_repair_entry(ddt_t *ddt, ddt_entry_t *dde, ddt_entry_t *rdde, zio_t *rio)
952 {
953 ddt_phys_t *ddp = dde->dde_phys;
954 ddt_phys_t *rddp = rdde->dde_phys;
955 ddt_key_t *ddk = &dde->dde_key;
956 ddt_key_t *rddk = &rdde->dde_key;
957 zio_t *zio;
958 blkptr_t blk;
959
960 zio = zio_null(rio, rio->io_spa, NULL,
961 ddt_repair_entry_done, rdde, rio->io_flags);
962
963 for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++, rddp++) {
964 if (ddp->ddp_phys_birth == 0 ||
965 ddp->ddp_phys_birth != rddp->ddp_phys_birth ||
966 bcmp(ddp->ddp_dva, rddp->ddp_dva, sizeof (ddp->ddp_dva)))
967 continue;
968 ddt_bp_create(ddt->ddt_checksum, ddk, ddp, &blk);
969 zio_nowait(zio_rewrite(zio, zio->io_spa, 0, &blk,
970 rdde->dde_repair_data, DDK_GET_PSIZE(rddk), NULL, NULL,
971 ZIO_PRIORITY_SYNC_WRITE, ZIO_DDT_CHILD_FLAGS(zio), NULL));
972 }
973
974 zio_nowait(zio);
975 }
976
977 static void
ddt_repair_table(ddt_t * ddt,zio_t * rio)978 ddt_repair_table(ddt_t *ddt, zio_t *rio)
979 {
980 spa_t *spa = ddt->ddt_spa;
981 ddt_entry_t *dde, *rdde_next, *rdde;
982 avl_tree_t *t = &ddt->ddt_repair_tree;
983 blkptr_t blk;
984
985 if (spa_sync_pass(spa) > 1)
986 return;
987
988 ddt_enter(ddt);
989 for (rdde = avl_first(t); rdde != NULL; rdde = rdde_next) {
990 rdde_next = AVL_NEXT(t, rdde);
991 avl_remove(&ddt->ddt_repair_tree, rdde);
992 ddt_exit(ddt);
993 ddt_bp_create(ddt->ddt_checksum, &rdde->dde_key, NULL, &blk);
994 dde = ddt_repair_start(ddt, &blk);
995 ddt_repair_entry(ddt, dde, rdde, rio);
996 ddt_repair_done(ddt, dde);
997 ddt_enter(ddt);
998 }
999 ddt_exit(ddt);
1000 }
1001
1002 static void
ddt_sync_entry(ddt_t * ddt,ddt_entry_t * dde,dmu_tx_t * tx,uint64_t txg)1003 ddt_sync_entry(ddt_t *ddt, ddt_entry_t *dde, dmu_tx_t *tx, uint64_t txg)
1004 {
1005 dsl_pool_t *dp = ddt->ddt_spa->spa_dsl_pool;
1006 ddt_phys_t *ddp = dde->dde_phys;
1007 ddt_key_t *ddk = &dde->dde_key;
1008 enum ddt_type otype = dde->dde_type;
1009 enum ddt_type ntype = DDT_TYPE_CURRENT;
1010 enum ddt_class oclass = dde->dde_class;
1011 enum ddt_class nclass;
1012 uint64_t total_refcnt = 0;
1013
1014 ASSERT(dde->dde_loaded);
1015 ASSERT(!dde->dde_loading);
1016
1017 for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
1018 ASSERT(dde->dde_lead_zio[p] == NULL);
1019 ASSERT((int64_t)ddp->ddp_refcnt >= 0);
1020 if (ddp->ddp_phys_birth == 0) {
1021 ASSERT(ddp->ddp_refcnt == 0);
1022 continue;
1023 }
1024 if (p == DDT_PHYS_DITTO) {
1025 if (ddt_ditto_copies_needed(ddt, dde, NULL) == 0)
1026 ddt_phys_free(ddt, ddk, ddp, txg);
1027 continue;
1028 }
1029 if (ddp->ddp_refcnt == 0)
1030 ddt_phys_free(ddt, ddk, ddp, txg);
1031 total_refcnt += ddp->ddp_refcnt;
1032 }
1033
1034 if (dde->dde_phys[DDT_PHYS_DITTO].ddp_phys_birth != 0)
1035 nclass = DDT_CLASS_DITTO;
1036 else if (total_refcnt > 1)
1037 nclass = DDT_CLASS_DUPLICATE;
1038 else
1039 nclass = DDT_CLASS_UNIQUE;
1040
1041 if (otype != DDT_TYPES &&
1042 (otype != ntype || oclass != nclass || total_refcnt == 0)) {
1043 VERIFY(ddt_object_remove(ddt, otype, oclass, dde, tx) == 0);
1044 ASSERT(ddt_object_lookup(ddt, otype, oclass, dde) == ENOENT);
1045 }
1046
1047 if (total_refcnt != 0) {
1048 dde->dde_type = ntype;
1049 dde->dde_class = nclass;
1050 ddt_stat_update(ddt, dde, 0);
1051 if (!ddt_object_exists(ddt, ntype, nclass))
1052 ddt_object_create(ddt, ntype, nclass, tx);
1053 VERIFY(ddt_object_update(ddt, ntype, nclass, dde, tx) == 0);
1054
1055 /*
1056 * If the class changes, the order that we scan this bp
1057 * changes. If it decreases, we could miss it, so
1058 * scan it right now. (This covers both class changing
1059 * while we are doing ddt_walk(), and when we are
1060 * traversing.)
1061 */
1062 if (nclass < oclass) {
1063 dsl_scan_ddt_entry(dp->dp_scan,
1064 ddt->ddt_checksum, dde, tx);
1065 }
1066 }
1067 }
1068
1069 static void
ddt_sync_table(ddt_t * ddt,dmu_tx_t * tx,uint64_t txg)1070 ddt_sync_table(ddt_t *ddt, dmu_tx_t *tx, uint64_t txg)
1071 {
1072 spa_t *spa = ddt->ddt_spa;
1073 ddt_entry_t *dde;
1074 void *cookie = NULL;
1075
1076 if (avl_numnodes(&ddt->ddt_tree) == 0)
1077 return;
1078
1079 ASSERT(spa->spa_uberblock.ub_version >= SPA_VERSION_DEDUP);
1080
1081 if (spa->spa_ddt_stat_object == 0) {
1082 spa->spa_ddt_stat_object = zap_create_link(ddt->ddt_os,
1083 DMU_OT_DDT_STATS, DMU_POOL_DIRECTORY_OBJECT,
1084 DMU_POOL_DDT_STATS, tx);
1085 }
1086
1087 while ((dde = avl_destroy_nodes(&ddt->ddt_tree, &cookie)) != NULL) {
1088 ddt_sync_entry(ddt, dde, tx, txg);
1089 ddt_free(dde);
1090 }
1091
1092 for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
1093 uint64_t add, count = 0;
1094 for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
1095 if (ddt_object_exists(ddt, type, class)) {
1096 ddt_object_sync(ddt, type, class, tx);
1097 VERIFY(ddt_object_count(ddt, type, class,
1098 &add) == 0);
1099 count += add;
1100 }
1101 }
1102 for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
1103 if (count == 0 && ddt_object_exists(ddt, type, class))
1104 ddt_object_destroy(ddt, type, class, tx);
1105 }
1106 }
1107
1108 bcopy(ddt->ddt_histogram, &ddt->ddt_histogram_cache,
1109 sizeof (ddt->ddt_histogram));
1110 }
1111
1112 void
ddt_sync(spa_t * spa,uint64_t txg)1113 ddt_sync(spa_t *spa, uint64_t txg)
1114 {
1115 dmu_tx_t *tx;
1116 zio_t *rio = zio_root(spa, NULL, NULL,
1117 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE);
1118
1119 ASSERT(spa_syncing_txg(spa) == txg);
1120
1121 tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
1122
1123 for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
1124 ddt_t *ddt = spa->spa_ddt[c];
1125 if (ddt == NULL)
1126 continue;
1127 ddt_sync_table(ddt, tx, txg);
1128 ddt_repair_table(ddt, rio);
1129 }
1130
1131 (void) zio_wait(rio);
1132
1133 dmu_tx_commit(tx);
1134 }
1135
1136 int
ddt_walk(spa_t * spa,ddt_bookmark_t * ddb,ddt_entry_t * dde)1137 ddt_walk(spa_t *spa, ddt_bookmark_t *ddb, ddt_entry_t *dde)
1138 {
1139 do {
1140 do {
1141 do {
1142 ddt_t *ddt = spa->spa_ddt[ddb->ddb_checksum];
1143 int error = ENOENT;
1144 if (ddt_object_exists(ddt, ddb->ddb_type,
1145 ddb->ddb_class)) {
1146 error = ddt_object_walk(ddt,
1147 ddb->ddb_type, ddb->ddb_class,
1148 &ddb->ddb_cursor, dde);
1149 }
1150 dde->dde_type = ddb->ddb_type;
1151 dde->dde_class = ddb->ddb_class;
1152 if (error == 0)
1153 return (0);
1154 if (error != ENOENT)
1155 return (error);
1156 ddb->ddb_cursor = 0;
1157 } while (++ddb->ddb_checksum < ZIO_CHECKSUM_FUNCTIONS);
1158 ddb->ddb_checksum = 0;
1159 } while (++ddb->ddb_type < DDT_TYPES);
1160 ddb->ddb_type = 0;
1161 } while (++ddb->ddb_class < DDT_CLASSES);
1162
1163 return (SET_ERROR(ENOENT));
1164 }
1165