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 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
24 * Copyright (c) 2012 by Delphix. All rights reserved.
25 * Copyright (c) 2013, Joyent, Inc. All rights reserved.
26 */
27
28 #include <sys/zfs_context.h>
29 #include <sys/dmu.h>
30 #include <sys/dmu_impl.h>
31 #include <sys/dbuf.h>
32 #include <sys/dmu_objset.h>
33 #include <sys/dsl_dataset.h>
34 #include <sys/dsl_dir.h>
35 #include <sys/dmu_tx.h>
36 #include <sys/spa.h>
37 #include <sys/zio.h>
38 #include <sys/dmu_zfetch.h>
39 #include <sys/sa.h>
40 #include <sys/sa_impl.h>
41
42 static void dbuf_destroy(dmu_buf_impl_t *db);
43 static int dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
44 static void dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx);
45
46 /*
47 * Global data structures and functions for the dbuf cache.
48 */
49 static kmem_cache_t *dbuf_cache;
50
51 /* ARGSUSED */
52 static int
53 dbuf_cons(void *vdb, void *unused, int kmflag)
54 {
55 dmu_buf_impl_t *db = vdb;
56 bzero(db, sizeof (dmu_buf_impl_t));
57
58 mutex_init(&db->db_mtx, NULL, MUTEX_DEFAULT, NULL);
59 cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL);
60 refcount_create(&db->db_holds);
61 return (0);
62 }
63
64 /* ARGSUSED */
65 static void
66 dbuf_dest(void *vdb, void *unused)
67 {
68 dmu_buf_impl_t *db = vdb;
69 mutex_destroy(&db->db_mtx);
70 cv_destroy(&db->db_changed);
71 refcount_destroy(&db->db_holds);
72 }
73
74 /*
75 * dbuf hash table routines
76 */
77 static dbuf_hash_table_t dbuf_hash_table;
78
79 static uint64_t dbuf_hash_count;
80
81 static uint64_t
82 dbuf_hash(void *os, uint64_t obj, uint8_t lvl, uint64_t blkid)
83 {
84 uintptr_t osv = (uintptr_t)os;
85 uint64_t crc = -1ULL;
86
87 ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY);
88 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (lvl)) & 0xFF];
89 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (osv >> 6)) & 0xFF];
90 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 0)) & 0xFF];
91 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 8)) & 0xFF];
92 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 0)) & 0xFF];
93 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 8)) & 0xFF];
94
95 crc ^= (osv>>14) ^ (obj>>16) ^ (blkid>>16);
96
97 return (crc);
98 }
99
100 #define DBUF_HASH(os, obj, level, blkid) dbuf_hash(os, obj, level, blkid);
101
102 #define DBUF_EQUAL(dbuf, os, obj, level, blkid) \
103 ((dbuf)->db.db_object == (obj) && \
104 (dbuf)->db_objset == (os) && \
105 (dbuf)->db_level == (level) && \
106 (dbuf)->db_blkid == (blkid))
107
108 dmu_buf_impl_t *
109 dbuf_find(dnode_t *dn, uint8_t level, uint64_t blkid)
110 {
111 dbuf_hash_table_t *h = &dbuf_hash_table;
112 objset_t *os = dn->dn_objset;
113 uint64_t obj = dn->dn_object;
114 uint64_t hv = DBUF_HASH(os, obj, level, blkid);
115 uint64_t idx = hv & h->hash_table_mask;
116 dmu_buf_impl_t *db;
117
118 mutex_enter(DBUF_HASH_MUTEX(h, idx));
119 for (db = h->hash_table[idx]; db != NULL; db = db->db_hash_next) {
120 if (DBUF_EQUAL(db, os, obj, level, blkid)) {
121 mutex_enter(&db->db_mtx);
122 if (db->db_state != DB_EVICTING) {
123 mutex_exit(DBUF_HASH_MUTEX(h, idx));
124 return (db);
125 }
126 mutex_exit(&db->db_mtx);
127 }
128 }
129 mutex_exit(DBUF_HASH_MUTEX(h, idx));
130 return (NULL);
131 }
132
133 /*
134 * Insert an entry into the hash table. If there is already an element
135 * equal to elem in the hash table, then the already existing element
136 * will be returned and the new element will not be inserted.
137 * Otherwise returns NULL.
138 */
139 static dmu_buf_impl_t *
140 dbuf_hash_insert(dmu_buf_impl_t *db)
141 {
142 dbuf_hash_table_t *h = &dbuf_hash_table;
143 objset_t *os = db->db_objset;
144 uint64_t obj = db->db.db_object;
145 int level = db->db_level;
146 uint64_t blkid = db->db_blkid;
147 uint64_t hv = DBUF_HASH(os, obj, level, blkid);
148 uint64_t idx = hv & h->hash_table_mask;
149 dmu_buf_impl_t *dbf;
150
151 mutex_enter(DBUF_HASH_MUTEX(h, idx));
152 for (dbf = h->hash_table[idx]; dbf != NULL; dbf = dbf->db_hash_next) {
153 if (DBUF_EQUAL(dbf, os, obj, level, blkid)) {
154 mutex_enter(&dbf->db_mtx);
155 if (dbf->db_state != DB_EVICTING) {
156 mutex_exit(DBUF_HASH_MUTEX(h, idx));
157 return (dbf);
158 }
159 mutex_exit(&dbf->db_mtx);
160 }
161 }
162
163 mutex_enter(&db->db_mtx);
164 db->db_hash_next = h->hash_table[idx];
165 h->hash_table[idx] = db;
166 mutex_exit(DBUF_HASH_MUTEX(h, idx));
167 atomic_add_64(&dbuf_hash_count, 1);
168
169 return (NULL);
170 }
171
172 /*
173 * Remove an entry from the hash table. This operation will
174 * fail if there are any existing holds on the db.
175 */
176 static void
177 dbuf_hash_remove(dmu_buf_impl_t *db)
178 {
179 dbuf_hash_table_t *h = &dbuf_hash_table;
180 uint64_t hv = DBUF_HASH(db->db_objset, db->db.db_object,
181 db->db_level, db->db_blkid);
182 uint64_t idx = hv & h->hash_table_mask;
183 dmu_buf_impl_t *dbf, **dbp;
184
185 /*
186 * We musn't hold db_mtx to maintin lock ordering:
187 * DBUF_HASH_MUTEX > db_mtx.
188 */
189 ASSERT(refcount_is_zero(&db->db_holds));
190 ASSERT(db->db_state == DB_EVICTING);
191 ASSERT(!MUTEX_HELD(&db->db_mtx));
192
193 mutex_enter(DBUF_HASH_MUTEX(h, idx));
194 dbp = &h->hash_table[idx];
195 while ((dbf = *dbp) != db) {
196 dbp = &dbf->db_hash_next;
197 ASSERT(dbf != NULL);
198 }
199 *dbp = db->db_hash_next;
200 db->db_hash_next = NULL;
201 mutex_exit(DBUF_HASH_MUTEX(h, idx));
202 atomic_add_64(&dbuf_hash_count, -1);
203 }
204
205 static arc_evict_func_t dbuf_do_evict;
206
207 static void
208 dbuf_evict_user(dmu_buf_impl_t *db)
209 {
210 ASSERT(MUTEX_HELD(&db->db_mtx));
211
212 if (db->db_level != 0 || db->db_evict_func == NULL)
213 return;
214
215 if (db->db_user_data_ptr_ptr)
216 *db->db_user_data_ptr_ptr = db->db.db_data;
217 db->db_evict_func(&db->db, db->db_user_ptr);
218 db->db_user_ptr = NULL;
219 db->db_user_data_ptr_ptr = NULL;
220 db->db_evict_func = NULL;
221 }
222
223 boolean_t
224 dbuf_is_metadata(dmu_buf_impl_t *db)
225 {
226 if (db->db_level > 0) {
227 return (B_TRUE);
228 } else {
229 boolean_t is_metadata;
230
231 DB_DNODE_ENTER(db);
232 is_metadata = DMU_OT_IS_METADATA(DB_DNODE(db)->dn_type);
233 DB_DNODE_EXIT(db);
234
235 return (is_metadata);
236 }
237 }
238
239 void
240 dbuf_evict(dmu_buf_impl_t *db)
241 {
242 ASSERT(MUTEX_HELD(&db->db_mtx));
243 ASSERT(db->db_buf == NULL);
244 ASSERT(db->db_data_pending == NULL);
245
246 dbuf_clear(db);
247 dbuf_destroy(db);
248 }
249
250 void
251 dbuf_init(void)
252 {
253 uint64_t hsize = 1ULL << 16;
254 dbuf_hash_table_t *h = &dbuf_hash_table;
255 int i;
256
257 /*
258 * The hash table is big enough to fill all of physical memory
259 * with an average 4K block size. The table will take up
260 * totalmem*sizeof(void*)/4K (i.e. 2MB/GB with 8-byte pointers).
261 */
262 while (hsize * 4096 < physmem * PAGESIZE)
263 hsize <<= 1;
264
265 retry:
266 h->hash_table_mask = hsize - 1;
267 h->hash_table = kmem_zalloc(hsize * sizeof (void *), KM_NOSLEEP);
268 if (h->hash_table == NULL) {
269 /* XXX - we should really return an error instead of assert */
270 ASSERT(hsize > (1ULL << 10));
271 hsize >>= 1;
272 goto retry;
273 }
274
275 dbuf_cache = kmem_cache_create("dmu_buf_impl_t",
276 sizeof (dmu_buf_impl_t),
277 0, dbuf_cons, dbuf_dest, NULL, NULL, NULL, 0);
278
279 for (i = 0; i < DBUF_MUTEXES; i++)
280 mutex_init(&h->hash_mutexes[i], NULL, MUTEX_DEFAULT, NULL);
281 }
282
283 void
284 dbuf_fini(void)
285 {
286 dbuf_hash_table_t *h = &dbuf_hash_table;
287 int i;
288
289 for (i = 0; i < DBUF_MUTEXES; i++)
290 mutex_destroy(&h->hash_mutexes[i]);
291 kmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *));
292 kmem_cache_destroy(dbuf_cache);
293 }
294
295 /*
296 * Other stuff.
297 */
298
299 #ifdef ZFS_DEBUG
300 static void
301 dbuf_verify(dmu_buf_impl_t *db)
302 {
303 dnode_t *dn;
304 dbuf_dirty_record_t *dr;
305
306 ASSERT(MUTEX_HELD(&db->db_mtx));
307
308 if (!(zfs_flags & ZFS_DEBUG_DBUF_VERIFY))
309 return;
310
311 ASSERT(db->db_objset != NULL);
312 DB_DNODE_ENTER(db);
313 dn = DB_DNODE(db);
314 if (dn == NULL) {
315 ASSERT(db->db_parent == NULL);
316 ASSERT(db->db_blkptr == NULL);
317 } else {
318 ASSERT3U(db->db.db_object, ==, dn->dn_object);
319 ASSERT3P(db->db_objset, ==, dn->dn_objset);
320 ASSERT3U(db->db_level, <, dn->dn_nlevels);
321 ASSERT(db->db_blkid == DMU_BONUS_BLKID ||
322 db->db_blkid == DMU_SPILL_BLKID ||
323 !list_is_empty(&dn->dn_dbufs));
324 }
325 if (db->db_blkid == DMU_BONUS_BLKID) {
326 ASSERT(dn != NULL);
327 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
328 ASSERT3U(db->db.db_offset, ==, DMU_BONUS_BLKID);
329 } else if (db->db_blkid == DMU_SPILL_BLKID) {
330 ASSERT(dn != NULL);
331 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
332 ASSERT0(db->db.db_offset);
333 } else {
334 ASSERT3U(db->db.db_offset, ==, db->db_blkid * db->db.db_size);
335 }
336
337 for (dr = db->db_data_pending; dr != NULL; dr = dr->dr_next)
338 ASSERT(dr->dr_dbuf == db);
339
340 for (dr = db->db_last_dirty; dr != NULL; dr = dr->dr_next)
341 ASSERT(dr->dr_dbuf == db);
342
343 /*
344 * We can't assert that db_size matches dn_datablksz because it
345 * can be momentarily different when another thread is doing
346 * dnode_set_blksz().
347 */
348 if (db->db_level == 0 && db->db.db_object == DMU_META_DNODE_OBJECT) {
349 dr = db->db_data_pending;
350 /*
351 * It should only be modified in syncing context, so
352 * make sure we only have one copy of the data.
353 */
354 ASSERT(dr == NULL || dr->dt.dl.dr_data == db->db_buf);
355 }
356
357 /* verify db->db_blkptr */
358 if (db->db_blkptr) {
359 if (db->db_parent == dn->dn_dbuf) {
360 /* db is pointed to by the dnode */
361 /* ASSERT3U(db->db_blkid, <, dn->dn_nblkptr); */
362 if (DMU_OBJECT_IS_SPECIAL(db->db.db_object))
363 ASSERT(db->db_parent == NULL);
364 else
365 ASSERT(db->db_parent != NULL);
366 if (db->db_blkid != DMU_SPILL_BLKID)
367 ASSERT3P(db->db_blkptr, ==,
368 &dn->dn_phys->dn_blkptr[db->db_blkid]);
369 } else {
370 /* db is pointed to by an indirect block */
371 int epb = db->db_parent->db.db_size >> SPA_BLKPTRSHIFT;
372 ASSERT3U(db->db_parent->db_level, ==, db->db_level+1);
373 ASSERT3U(db->db_parent->db.db_object, ==,
374 db->db.db_object);
375 /*
376 * dnode_grow_indblksz() can make this fail if we don't
377 * have the struct_rwlock. XXX indblksz no longer
378 * grows. safe to do this now?
379 */
380 if (RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
381 ASSERT3P(db->db_blkptr, ==,
382 ((blkptr_t *)db->db_parent->db.db_data +
383 db->db_blkid % epb));
384 }
385 }
386 }
387 if ((db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr)) &&
388 (db->db_buf == NULL || db->db_buf->b_data) &&
389 db->db.db_data && db->db_blkid != DMU_BONUS_BLKID &&
390 db->db_state != DB_FILL && !dn->dn_free_txg) {
391 /*
392 * If the blkptr isn't set but they have nonzero data,
393 * it had better be dirty, otherwise we'll lose that
394 * data when we evict this buffer.
395 */
396 if (db->db_dirtycnt == 0) {
397 uint64_t *buf = db->db.db_data;
398 int i;
399
400 for (i = 0; i < db->db.db_size >> 3; i++) {
401 ASSERT(buf[i] == 0);
402 }
403 }
404 }
405 DB_DNODE_EXIT(db);
406 }
407 #endif
408
409 static void
410 dbuf_update_data(dmu_buf_impl_t *db)
411 {
412 ASSERT(MUTEX_HELD(&db->db_mtx));
413 if (db->db_level == 0 && db->db_user_data_ptr_ptr) {
414 ASSERT(!refcount_is_zero(&db->db_holds));
415 *db->db_user_data_ptr_ptr = db->db.db_data;
416 }
417 }
418
419 static void
420 dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf)
421 {
422 ASSERT(MUTEX_HELD(&db->db_mtx));
423 ASSERT(db->db_buf == NULL || !arc_has_callback(db->db_buf));
424 db->db_buf = buf;
425 if (buf != NULL) {
426 ASSERT(buf->b_data != NULL);
427 db->db.db_data = buf->b_data;
428 if (!arc_released(buf))
429 arc_set_callback(buf, dbuf_do_evict, db);
430 dbuf_update_data(db);
431 } else {
432 dbuf_evict_user(db);
433 db->db.db_data = NULL;
434 if (db->db_state != DB_NOFILL)
435 db->db_state = DB_UNCACHED;
436 }
437 }
438
439 /*
440 * Loan out an arc_buf for read. Return the loaned arc_buf.
441 */
442 arc_buf_t *
443 dbuf_loan_arcbuf(dmu_buf_impl_t *db)
444 {
445 arc_buf_t *abuf;
446
447 mutex_enter(&db->db_mtx);
448 if (arc_released(db->db_buf) || refcount_count(&db->db_holds) > 1) {
449 int blksz = db->db.db_size;
450 spa_t *spa;
451
452 mutex_exit(&db->db_mtx);
453 DB_GET_SPA(&spa, db);
454 abuf = arc_loan_buf(spa, blksz);
455 bcopy(db->db.db_data, abuf->b_data, blksz);
456 } else {
457 abuf = db->db_buf;
458 arc_loan_inuse_buf(abuf, db);
459 dbuf_set_data(db, NULL);
460 mutex_exit(&db->db_mtx);
461 }
462 return (abuf);
463 }
464
465 uint64_t
466 dbuf_whichblock(dnode_t *dn, uint64_t offset)
467 {
468 if (dn->dn_datablkshift) {
469 return (offset >> dn->dn_datablkshift);
470 } else {
471 ASSERT3U(offset, <, dn->dn_datablksz);
472 return (0);
473 }
474 }
475
476 static void
477 dbuf_read_done(zio_t *zio, arc_buf_t *buf, void *vdb)
478 {
479 dmu_buf_impl_t *db = vdb;
480
481 mutex_enter(&db->db_mtx);
482 ASSERT3U(db->db_state, ==, DB_READ);
483 /*
484 * All reads are synchronous, so we must have a hold on the dbuf
485 */
486 ASSERT(refcount_count(&db->db_holds) > 0);
487 ASSERT(db->db_buf == NULL);
488 ASSERT(db->db.db_data == NULL);
489 if (db->db_level == 0 && db->db_freed_in_flight) {
490 /* we were freed in flight; disregard any error */
491 arc_release(buf, db);
492 bzero(buf->b_data, db->db.db_size);
493 arc_buf_freeze(buf);
494 db->db_freed_in_flight = FALSE;
495 dbuf_set_data(db, buf);
496 db->db_state = DB_CACHED;
497 } else if (zio == NULL || zio->io_error == 0) {
498 dbuf_set_data(db, buf);
499 db->db_state = DB_CACHED;
500 } else {
501 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
502 ASSERT3P(db->db_buf, ==, NULL);
503 VERIFY(arc_buf_remove_ref(buf, db) == 1);
504 db->db_state = DB_UNCACHED;
505 }
506 cv_broadcast(&db->db_changed);
507 dbuf_rele_and_unlock(db, NULL);
508 }
509
510 static void
511 dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t *flags)
512 {
513 dnode_t *dn;
514 spa_t *spa;
515 zbookmark_t zb;
516 uint32_t aflags = ARC_NOWAIT;
517 arc_buf_t *pbuf;
518
519 DB_DNODE_ENTER(db);
520 dn = DB_DNODE(db);
521 ASSERT(!refcount_is_zero(&db->db_holds));
522 /* We need the struct_rwlock to prevent db_blkptr from changing. */
523 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
524 ASSERT(MUTEX_HELD(&db->db_mtx));
525 ASSERT(db->db_state == DB_UNCACHED);
526 ASSERT(db->db_buf == NULL);
527
528 if (db->db_blkid == DMU_BONUS_BLKID) {
529 int bonuslen = MIN(dn->dn_bonuslen, dn->dn_phys->dn_bonuslen);
530
531 ASSERT3U(bonuslen, <=, db->db.db_size);
532 db->db.db_data = zio_buf_alloc(DN_MAX_BONUSLEN);
533 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
534 if (bonuslen < DN_MAX_BONUSLEN)
535 bzero(db->db.db_data, DN_MAX_BONUSLEN);
536
537 if (bonuslen) {
538 /*
539 * Absent byzantine on-disk corruption, we fully expect
540 * our bonuslen to be no more than DN_MAX_BONUSLEN --
541 * but we nonetheless explicitly clamp it on the bcopy()
542 * to prevent any on-disk corruption from becoming
543 * rampant in-kernel corruption.
544 */
545 bcopy(DN_BONUS(dn->dn_phys), db->db.db_data,
546 MIN(bonuslen, DN_MAX_BONUSLEN));
547 }
548
549 DB_DNODE_EXIT(db);
550 dbuf_update_data(db);
551 db->db_state = DB_CACHED;
552 mutex_exit(&db->db_mtx);
553 return;
554 }
555
556 /*
557 * Recheck BP_IS_HOLE() after dnode_block_freed() in case dnode_sync()
558 * processes the delete record and clears the bp while we are waiting
559 * for the dn_mtx (resulting in a "no" from block_freed).
560 */
561 if (db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr) ||
562 (db->db_level == 0 && (dnode_block_freed(dn, db->db_blkid) ||
563 BP_IS_HOLE(db->db_blkptr)))) {
564 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
565
566 dbuf_set_data(db, arc_buf_alloc(dn->dn_objset->os_spa,
567 db->db.db_size, db, type));
568 DB_DNODE_EXIT(db);
569 bzero(db->db.db_data, db->db.db_size);
570 db->db_state = DB_CACHED;
571 *flags |= DB_RF_CACHED;
572 mutex_exit(&db->db_mtx);
573 return;
574 }
575
576 spa = dn->dn_objset->os_spa;
577 DB_DNODE_EXIT(db);
578
579 db->db_state = DB_READ;
580 mutex_exit(&db->db_mtx);
581
582 if (DBUF_IS_L2CACHEABLE(db))
583 aflags |= ARC_L2CACHE;
584
585 SET_BOOKMARK(&zb, db->db_objset->os_dsl_dataset ?
586 db->db_objset->os_dsl_dataset->ds_object : DMU_META_OBJSET,
587 db->db.db_object, db->db_level, db->db_blkid);
588
589 dbuf_add_ref(db, NULL);
590 /* ZIO_FLAG_CANFAIL callers have to check the parent zio's error */
591
592 if (db->db_parent)
593 pbuf = db->db_parent->db_buf;
594 else
595 pbuf = db->db_objset->os_phys_buf;
596
597 (void) dsl_read(zio, spa, db->db_blkptr, pbuf,
598 dbuf_read_done, db, ZIO_PRIORITY_SYNC_READ,
599 (*flags & DB_RF_CANFAIL) ? ZIO_FLAG_CANFAIL : ZIO_FLAG_MUSTSUCCEED,
600 &aflags, &zb);
601 if (aflags & ARC_CACHED)
602 *flags |= DB_RF_CACHED;
603 }
604
605 int
606 dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
607 {
608 int err = 0;
609 int havepzio = (zio != NULL);
610 int prefetch;
611 dnode_t *dn;
612
613 /*
614 * We don't have to hold the mutex to check db_state because it
615 * can't be freed while we have a hold on the buffer.
616 */
617 ASSERT(!refcount_is_zero(&db->db_holds));
618
619 if (db->db_state == DB_NOFILL)
620 return (EIO);
621
622 DB_DNODE_ENTER(db);
623 dn = DB_DNODE(db);
624 if ((flags & DB_RF_HAVESTRUCT) == 0)
625 rw_enter(&dn->dn_struct_rwlock, RW_READER);
626
627 prefetch = db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
628 (flags & DB_RF_NOPREFETCH) == 0 && dn != NULL &&
629 DBUF_IS_CACHEABLE(db);
630
631 mutex_enter(&db->db_mtx);
632 if (db->db_state == DB_CACHED) {
633 mutex_exit(&db->db_mtx);
634 if (prefetch)
635 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset,
636 db->db.db_size, TRUE);
637 if ((flags & DB_RF_HAVESTRUCT) == 0)
638 rw_exit(&dn->dn_struct_rwlock);
639 DB_DNODE_EXIT(db);
640 } else if (db->db_state == DB_UNCACHED) {
641 spa_t *spa = dn->dn_objset->os_spa;
642
643 if (zio == NULL)
644 zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL);
645 dbuf_read_impl(db, zio, &flags);
646
647 /* dbuf_read_impl has dropped db_mtx for us */
648
649 if (prefetch)
650 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset,
651 db->db.db_size, flags & DB_RF_CACHED);
652
653 if ((flags & DB_RF_HAVESTRUCT) == 0)
654 rw_exit(&dn->dn_struct_rwlock);
655 DB_DNODE_EXIT(db);
656
657 if (!havepzio)
658 err = zio_wait(zio);
659 } else {
660 mutex_exit(&db->db_mtx);
661 if (prefetch)
662 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset,
663 db->db.db_size, TRUE);
664 if ((flags & DB_RF_HAVESTRUCT) == 0)
665 rw_exit(&dn->dn_struct_rwlock);
666 DB_DNODE_EXIT(db);
667
668 mutex_enter(&db->db_mtx);
669 if ((flags & DB_RF_NEVERWAIT) == 0) {
670 while (db->db_state == DB_READ ||
671 db->db_state == DB_FILL) {
672 ASSERT(db->db_state == DB_READ ||
673 (flags & DB_RF_HAVESTRUCT) == 0);
674 cv_wait(&db->db_changed, &db->db_mtx);
675 }
676 if (db->db_state == DB_UNCACHED)
677 err = EIO;
678 }
679 mutex_exit(&db->db_mtx);
680 }
681
682 ASSERT(err || havepzio || db->db_state == DB_CACHED);
683 return (err);
684 }
685
686 static void
687 dbuf_noread(dmu_buf_impl_t *db)
688 {
689 ASSERT(!refcount_is_zero(&db->db_holds));
690 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
691 mutex_enter(&db->db_mtx);
692 while (db->db_state == DB_READ || db->db_state == DB_FILL)
693 cv_wait(&db->db_changed, &db->db_mtx);
694 if (db->db_state == DB_UNCACHED) {
695 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
696 spa_t *spa;
697
698 ASSERT(db->db_buf == NULL);
699 ASSERT(db->db.db_data == NULL);
700 DB_GET_SPA(&spa, db);
701 dbuf_set_data(db, arc_buf_alloc(spa, db->db.db_size, db, type));
702 db->db_state = DB_FILL;
703 } else if (db->db_state == DB_NOFILL) {
704 dbuf_set_data(db, NULL);
705 } else {
706 ASSERT3U(db->db_state, ==, DB_CACHED);
707 }
708 mutex_exit(&db->db_mtx);
709 }
710
711 /*
712 * This is our just-in-time copy function. It makes a copy of
713 * buffers, that have been modified in a previous transaction
714 * group, before we modify them in the current active group.
715 *
716 * This function is used in two places: when we are dirtying a
717 * buffer for the first time in a txg, and when we are freeing
718 * a range in a dnode that includes this buffer.
719 *
720 * Note that when we are called from dbuf_free_range() we do
721 * not put a hold on the buffer, we just traverse the active
722 * dbuf list for the dnode.
723 */
724 static void
725 dbuf_fix_old_data(dmu_buf_impl_t *db, uint64_t txg)
726 {
727 dbuf_dirty_record_t *dr = db->db_last_dirty;
728
729 ASSERT(MUTEX_HELD(&db->db_mtx));
730 ASSERT(db->db.db_data != NULL);
731 ASSERT(db->db_level == 0);
732 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT);
733
734 if (dr == NULL ||
735 (dr->dt.dl.dr_data !=
736 ((db->db_blkid == DMU_BONUS_BLKID) ? db->db.db_data : db->db_buf)))
737 return;
738
739 /*
740 * If the last dirty record for this dbuf has not yet synced
741 * and its referencing the dbuf data, either:
742 * reset the reference to point to a new copy,
743 * or (if there a no active holders)
744 * just null out the current db_data pointer.
745 */
746 ASSERT(dr->dr_txg >= txg - 2);
747 if (db->db_blkid == DMU_BONUS_BLKID) {
748 /* Note that the data bufs here are zio_bufs */
749 dr->dt.dl.dr_data = zio_buf_alloc(DN_MAX_BONUSLEN);
750 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
751 bcopy(db->db.db_data, dr->dt.dl.dr_data, DN_MAX_BONUSLEN);
752 } else if (refcount_count(&db->db_holds) > db->db_dirtycnt) {
753 int size = db->db.db_size;
754 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
755 spa_t *spa;
756
757 DB_GET_SPA(&spa, db);
758 dr->dt.dl.dr_data = arc_buf_alloc(spa, size, db, type);
759 bcopy(db->db.db_data, dr->dt.dl.dr_data->b_data, size);
760 } else {
761 dbuf_set_data(db, NULL);
762 }
763 }
764
765 void
766 dbuf_unoverride(dbuf_dirty_record_t *dr)
767 {
768 dmu_buf_impl_t *db = dr->dr_dbuf;
769 blkptr_t *bp = &dr->dt.dl.dr_overridden_by;
770 uint64_t txg = dr->dr_txg;
771
772 ASSERT(MUTEX_HELD(&db->db_mtx));
773 ASSERT(dr->dt.dl.dr_override_state != DR_IN_DMU_SYNC);
774 ASSERT(db->db_level == 0);
775
776 if (db->db_blkid == DMU_BONUS_BLKID ||
777 dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN)
778 return;
779
780 ASSERT(db->db_data_pending != dr);
781
782 /* free this block */
783 if (!BP_IS_HOLE(bp) && !dr->dt.dl.dr_nopwrite) {
784 spa_t *spa;
785
786 DB_GET_SPA(&spa, db);
787 zio_free(spa, txg, bp);
788 }
789 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
790 dr->dt.dl.dr_nopwrite = B_FALSE;
791
792 /*
793 * Release the already-written buffer, so we leave it in
794 * a consistent dirty state. Note that all callers are
795 * modifying the buffer, so they will immediately do
796 * another (redundant) arc_release(). Therefore, leave
797 * the buf thawed to save the effort of freezing &
798 * immediately re-thawing it.
799 */
800 arc_release(dr->dt.dl.dr_data, db);
801 }
802
803 /*
804 * Evict (if its unreferenced) or clear (if its referenced) any level-0
805 * data blocks in the free range, so that any future readers will find
806 * empty blocks. Also, if we happen accross any level-1 dbufs in the
807 * range that have not already been marked dirty, mark them dirty so
808 * they stay in memory.
809 */
810 void
811 dbuf_free_range(dnode_t *dn, uint64_t start, uint64_t end, dmu_tx_t *tx)
812 {
813 dmu_buf_impl_t *db, *db_next;
814 uint64_t txg = tx->tx_txg;
815 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
816 uint64_t first_l1 = start >> epbs;
817 uint64_t last_l1 = end >> epbs;
818
819 if (end > dn->dn_maxblkid && (end != DMU_SPILL_BLKID)) {
820 end = dn->dn_maxblkid;
821 last_l1 = end >> epbs;
822 }
823 dprintf_dnode(dn, "start=%llu end=%llu\n", start, end);
824 mutex_enter(&dn->dn_dbufs_mtx);
825 for (db = list_head(&dn->dn_dbufs); db; db = db_next) {
826 db_next = list_next(&dn->dn_dbufs, db);
827 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
828
829 if (db->db_level == 1 &&
830 db->db_blkid >= first_l1 && db->db_blkid <= last_l1) {
831 mutex_enter(&db->db_mtx);
832 if (db->db_last_dirty &&
833 db->db_last_dirty->dr_txg < txg) {
834 dbuf_add_ref(db, FTAG);
835 mutex_exit(&db->db_mtx);
836 dbuf_will_dirty(db, tx);
837 dbuf_rele(db, FTAG);
838 } else {
839 mutex_exit(&db->db_mtx);
840 }
841 }
842
843 if (db->db_level != 0)
844 continue;
845 dprintf_dbuf(db, "found buf %s\n", "");
846 if (db->db_blkid < start || db->db_blkid > end)
847 continue;
848
849 /* found a level 0 buffer in the range */
850 if (dbuf_undirty(db, tx))
851 continue;
852
853 mutex_enter(&db->db_mtx);
854 if (db->db_state == DB_UNCACHED ||
855 db->db_state == DB_NOFILL ||
856 db->db_state == DB_EVICTING) {
857 ASSERT(db->db.db_data == NULL);
858 mutex_exit(&db->db_mtx);
859 continue;
860 }
861 if (db->db_state == DB_READ || db->db_state == DB_FILL) {
862 /* will be handled in dbuf_read_done or dbuf_rele */
863 db->db_freed_in_flight = TRUE;
864 mutex_exit(&db->db_mtx);
865 continue;
866 }
867 if (refcount_count(&db->db_holds) == 0) {
868 ASSERT(db->db_buf);
869 dbuf_clear(db);
870 continue;
871 }
872 /* The dbuf is referenced */
873
874 if (db->db_last_dirty != NULL) {
875 dbuf_dirty_record_t *dr = db->db_last_dirty;
876
877 if (dr->dr_txg == txg) {
878 /*
879 * This buffer is "in-use", re-adjust the file
880 * size to reflect that this buffer may
881 * contain new data when we sync.
882 */
883 if (db->db_blkid != DMU_SPILL_BLKID &&
884 db->db_blkid > dn->dn_maxblkid)
885 dn->dn_maxblkid = db->db_blkid;
886 dbuf_unoverride(dr);
887 } else {
888 /*
889 * This dbuf is not dirty in the open context.
890 * Either uncache it (if its not referenced in
891 * the open context) or reset its contents to
892 * empty.
893 */
894 dbuf_fix_old_data(db, txg);
895 }
896 }
897 /* clear the contents if its cached */
898 if (db->db_state == DB_CACHED) {
899 ASSERT(db->db.db_data != NULL);
900 arc_release(db->db_buf, db);
901 bzero(db->db.db_data, db->db.db_size);
902 arc_buf_freeze(db->db_buf);
903 }
904
905 mutex_exit(&db->db_mtx);
906 }
907 mutex_exit(&dn->dn_dbufs_mtx);
908 }
909
910 static int
911 dbuf_block_freeable(dmu_buf_impl_t *db)
912 {
913 dsl_dataset_t *ds = db->db_objset->os_dsl_dataset;
914 uint64_t birth_txg = 0;
915
916 /*
917 * We don't need any locking to protect db_blkptr:
918 * If it's syncing, then db_last_dirty will be set
919 * so we'll ignore db_blkptr.
920 */
921 ASSERT(MUTEX_HELD(&db->db_mtx));
922 if (db->db_last_dirty)
923 birth_txg = db->db_last_dirty->dr_txg;
924 else if (db->db_blkptr)
925 birth_txg = db->db_blkptr->blk_birth;
926
927 /*
928 * If we don't exist or are in a snapshot, we can't be freed.
929 * Don't pass the bp to dsl_dataset_block_freeable() since we
930 * are holding the db_mtx lock and might deadlock if we are
931 * prefetching a dedup-ed block.
932 */
933 if (birth_txg)
934 return (ds == NULL ||
935 dsl_dataset_block_freeable(ds, NULL, birth_txg));
936 else
937 return (FALSE);
938 }
939
940 void
941 dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx)
942 {
943 arc_buf_t *buf, *obuf;
944 int osize = db->db.db_size;
945 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
946 dnode_t *dn;
947
948 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
949
950 DB_DNODE_ENTER(db);
951 dn = DB_DNODE(db);
952
953 /* XXX does *this* func really need the lock? */
954 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
955
956 /*
957 * This call to dbuf_will_dirty() with the dn_struct_rwlock held
958 * is OK, because there can be no other references to the db
959 * when we are changing its size, so no concurrent DB_FILL can
960 * be happening.
961 */
962 /*
963 * XXX we should be doing a dbuf_read, checking the return
964 * value and returning that up to our callers
965 */
966 dbuf_will_dirty(db, tx);
967
968 /* create the data buffer for the new block */
969 buf = arc_buf_alloc(dn->dn_objset->os_spa, size, db, type);
970
971 /* copy old block data to the new block */
972 obuf = db->db_buf;
973 bcopy(obuf->b_data, buf->b_data, MIN(osize, size));
974 /* zero the remainder */
975 if (size > osize)
976 bzero((uint8_t *)buf->b_data + osize, size - osize);
977
978 mutex_enter(&db->db_mtx);
979 dbuf_set_data(db, buf);
980 VERIFY(arc_buf_remove_ref(obuf, db) == 1);
981 db->db.db_size = size;
982
983 if (db->db_level == 0) {
984 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
985 db->db_last_dirty->dt.dl.dr_data = buf;
986 }
987 mutex_exit(&db->db_mtx);
988
989 dnode_willuse_space(dn, size-osize, tx);
990 DB_DNODE_EXIT(db);
991 }
992
993 void
994 dbuf_release_bp(dmu_buf_impl_t *db)
995 {
996 objset_t *os;
997 zbookmark_t zb;
998
999 DB_GET_OBJSET(&os, db);
1000 ASSERT(dsl_pool_sync_context(dmu_objset_pool(os)));
1001 ASSERT(arc_released(os->os_phys_buf) ||
1002 list_link_active(&os->os_dsl_dataset->ds_synced_link));
1003 ASSERT(db->db_parent == NULL || arc_released(db->db_parent->db_buf));
1004
1005 zb.zb_objset = os->os_dsl_dataset ?
1006 os->os_dsl_dataset->ds_object : 0;
1007 zb.zb_object = db->db.db_object;
1008 zb.zb_level = db->db_level;
1009 zb.zb_blkid = db->db_blkid;
1010 (void) arc_release_bp(db->db_buf, db,
1011 db->db_blkptr, os->os_spa, &zb);
1012 }
1013
1014 dbuf_dirty_record_t *
1015 dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1016 {
1017 dnode_t *dn;
1018 objset_t *os;
1019 dbuf_dirty_record_t **drp, *dr;
1020 int drop_struct_lock = FALSE;
1021 boolean_t do_free_accounting = B_FALSE;
1022 int txgoff = tx->tx_txg & TXG_MASK;
1023
1024 ASSERT(tx->tx_txg != 0);
1025 ASSERT(!refcount_is_zero(&db->db_holds));
1026 DMU_TX_DIRTY_BUF(tx, db);
1027
1028 DB_DNODE_ENTER(db);
1029 dn = DB_DNODE(db);
1030 /*
1031 * Shouldn't dirty a regular buffer in syncing context. Private
1032 * objects may be dirtied in syncing context, but only if they
1033 * were already pre-dirtied in open context.
1034 */
1035 ASSERT(!dmu_tx_is_syncing(tx) ||
1036 BP_IS_HOLE(dn->dn_objset->os_rootbp) ||
1037 DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1038 dn->dn_objset->os_dsl_dataset == NULL);
1039 /*
1040 * We make this assert for private objects as well, but after we
1041 * check if we're already dirty. They are allowed to re-dirty
1042 * in syncing context.
1043 */
1044 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1045 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1046 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1047
1048 mutex_enter(&db->db_mtx);
1049 /*
1050 * XXX make this true for indirects too? The problem is that
1051 * transactions created with dmu_tx_create_assigned() from
1052 * syncing context don't bother holding ahead.
1053 */
1054 ASSERT(db->db_level != 0 ||
1055 db->db_state == DB_CACHED || db->db_state == DB_FILL ||
1056 db->db_state == DB_NOFILL);
1057
1058 mutex_enter(&dn->dn_mtx);
1059 /*
1060 * Don't set dirtyctx to SYNC if we're just modifying this as we
1061 * initialize the objset.
1062 */
1063 if (dn->dn_dirtyctx == DN_UNDIRTIED &&
1064 !BP_IS_HOLE(dn->dn_objset->os_rootbp)) {
1065 dn->dn_dirtyctx =
1066 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN);
1067 ASSERT(dn->dn_dirtyctx_firstset == NULL);
1068 dn->dn_dirtyctx_firstset = kmem_alloc(1, KM_SLEEP);
1069 }
1070 mutex_exit(&dn->dn_mtx);
1071
1072 if (db->db_blkid == DMU_SPILL_BLKID)
1073 dn->dn_have_spill = B_TRUE;
1074
1075 /*
1076 * If this buffer is already dirty, we're done.
1077 */
1078 drp = &db->db_last_dirty;
1079 ASSERT(*drp == NULL || (*drp)->dr_txg <= tx->tx_txg ||
1080 db->db.db_object == DMU_META_DNODE_OBJECT);
1081 while ((dr = *drp) != NULL && dr->dr_txg > tx->tx_txg)
1082 drp = &dr->dr_next;
1083 if (dr && dr->dr_txg == tx->tx_txg) {
1084 DB_DNODE_EXIT(db);
1085
1086 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID) {
1087 /*
1088 * If this buffer has already been written out,
1089 * we now need to reset its state.
1090 */
1091 dbuf_unoverride(dr);
1092 if (db->db.db_object != DMU_META_DNODE_OBJECT &&
1093 db->db_state != DB_NOFILL)
1094 arc_buf_thaw(db->db_buf);
1095 }
1096 mutex_exit(&db->db_mtx);
1097 return (dr);
1098 }
1099
1100 /*
1101 * Only valid if not already dirty.
1102 */
1103 ASSERT(dn->dn_object == 0 ||
1104 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1105 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1106
1107 ASSERT3U(dn->dn_nlevels, >, db->db_level);
1108 ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) ||
1109 dn->dn_phys->dn_nlevels > db->db_level ||
1110 dn->dn_next_nlevels[txgoff] > db->db_level ||
1111 dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level ||
1112 dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level);
1113
1114 /*
1115 * We should only be dirtying in syncing context if it's the
1116 * mos or we're initializing the os or it's a special object.
1117 * However, we are allowed to dirty in syncing context provided
1118 * we already dirtied it in open context. Hence we must make
1119 * this assertion only if we're not already dirty.
1120 */
1121 os = dn->dn_objset;
1122 ASSERT(!dmu_tx_is_syncing(tx) || DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1123 os->os_dsl_dataset == NULL || BP_IS_HOLE(os->os_rootbp));
1124 ASSERT(db->db.db_size != 0);
1125
1126 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1127
1128 if (db->db_blkid != DMU_BONUS_BLKID) {
1129 /*
1130 * Update the accounting.
1131 * Note: we delay "free accounting" until after we drop
1132 * the db_mtx. This keeps us from grabbing other locks
1133 * (and possibly deadlocking) in bp_get_dsize() while
1134 * also holding the db_mtx.
1135 */
1136 dnode_willuse_space(dn, db->db.db_size, tx);
1137 do_free_accounting = dbuf_block_freeable(db);
1138 }
1139
1140 /*
1141 * If this buffer is dirty in an old transaction group we need
1142 * to make a copy of it so that the changes we make in this
1143 * transaction group won't leak out when we sync the older txg.
1144 */
1145 dr = kmem_zalloc(sizeof (dbuf_dirty_record_t), KM_SLEEP);
1146 if (db->db_level == 0) {
1147 void *data_old = db->db_buf;
1148
1149 if (db->db_state != DB_NOFILL) {
1150 if (db->db_blkid == DMU_BONUS_BLKID) {
1151 dbuf_fix_old_data(db, tx->tx_txg);
1152 data_old = db->db.db_data;
1153 } else if (db->db.db_object != DMU_META_DNODE_OBJECT) {
1154 /*
1155 * Release the data buffer from the cache so
1156 * that we can modify it without impacting
1157 * possible other users of this cached data
1158 * block. Note that indirect blocks and
1159 * private objects are not released until the
1160 * syncing state (since they are only modified
1161 * then).
1162 */
1163 arc_release(db->db_buf, db);
1164 dbuf_fix_old_data(db, tx->tx_txg);
1165 data_old = db->db_buf;
1166 }
1167 ASSERT(data_old != NULL);
1168 }
1169 dr->dt.dl.dr_data = data_old;
1170 } else {
1171 mutex_init(&dr->dt.di.dr_mtx, NULL, MUTEX_DEFAULT, NULL);
1172 list_create(&dr->dt.di.dr_children,
1173 sizeof (dbuf_dirty_record_t),
1174 offsetof(dbuf_dirty_record_t, dr_dirty_node));
1175 }
1176 dr->dr_dbuf = db;
1177 dr->dr_txg = tx->tx_txg;
1178 dr->dr_next = *drp;
1179 *drp = dr;
1180
1181 /*
1182 * We could have been freed_in_flight between the dbuf_noread
1183 * and dbuf_dirty. We win, as though the dbuf_noread() had
1184 * happened after the free.
1185 */
1186 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
1187 db->db_blkid != DMU_SPILL_BLKID) {
1188 mutex_enter(&dn->dn_mtx);
1189 dnode_clear_range(dn, db->db_blkid, 1, tx);
1190 mutex_exit(&dn->dn_mtx);
1191 db->db_freed_in_flight = FALSE;
1192 }
1193
1194 /*
1195 * This buffer is now part of this txg
1196 */
1197 dbuf_add_ref(db, (void *)(uintptr_t)tx->tx_txg);
1198 db->db_dirtycnt += 1;
1199 ASSERT3U(db->db_dirtycnt, <=, 3);
1200
1201 mutex_exit(&db->db_mtx);
1202
1203 if (db->db_blkid == DMU_BONUS_BLKID ||
1204 db->db_blkid == DMU_SPILL_BLKID) {
1205 mutex_enter(&dn->dn_mtx);
1206 ASSERT(!list_link_active(&dr->dr_dirty_node));
1207 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1208 mutex_exit(&dn->dn_mtx);
1209 dnode_setdirty(dn, tx);
1210 DB_DNODE_EXIT(db);
1211 return (dr);
1212 } else if (do_free_accounting) {
1213 blkptr_t *bp = db->db_blkptr;
1214 int64_t willfree = (bp && !BP_IS_HOLE(bp)) ?
1215 bp_get_dsize(os->os_spa, bp) : db->db.db_size;
1216 /*
1217 * This is only a guess -- if the dbuf is dirty
1218 * in a previous txg, we don't know how much
1219 * space it will use on disk yet. We should
1220 * really have the struct_rwlock to access
1221 * db_blkptr, but since this is just a guess,
1222 * it's OK if we get an odd answer.
1223 */
1224 ddt_prefetch(os->os_spa, bp);
1225 dnode_willuse_space(dn, -willfree, tx);
1226 }
1227
1228 if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
1229 rw_enter(&dn->dn_struct_rwlock, RW_READER);
1230 drop_struct_lock = TRUE;
1231 }
1232
1233 if (db->db_level == 0) {
1234 dnode_new_blkid(dn, db->db_blkid, tx, drop_struct_lock);
1235 ASSERT(dn->dn_maxblkid >= db->db_blkid);
1236 }
1237
1238 if (db->db_level+1 < dn->dn_nlevels) {
1239 dmu_buf_impl_t *parent = db->db_parent;
1240 dbuf_dirty_record_t *di;
1241 int parent_held = FALSE;
1242
1243 if (db->db_parent == NULL || db->db_parent == dn->dn_dbuf) {
1244 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1245
1246 parent = dbuf_hold_level(dn, db->db_level+1,
1247 db->db_blkid >> epbs, FTAG);
1248 ASSERT(parent != NULL);
1249 parent_held = TRUE;
1250 }
1251 if (drop_struct_lock)
1252 rw_exit(&dn->dn_struct_rwlock);
1253 ASSERT3U(db->db_level+1, ==, parent->db_level);
1254 di = dbuf_dirty(parent, tx);
1255 if (parent_held)
1256 dbuf_rele(parent, FTAG);
1257
1258 mutex_enter(&db->db_mtx);
1259 /* possible race with dbuf_undirty() */
1260 if (db->db_last_dirty == dr ||
1261 dn->dn_object == DMU_META_DNODE_OBJECT) {
1262 mutex_enter(&di->dt.di.dr_mtx);
1263 ASSERT3U(di->dr_txg, ==, tx->tx_txg);
1264 ASSERT(!list_link_active(&dr->dr_dirty_node));
1265 list_insert_tail(&di->dt.di.dr_children, dr);
1266 mutex_exit(&di->dt.di.dr_mtx);
1267 dr->dr_parent = di;
1268 }
1269 mutex_exit(&db->db_mtx);
1270 } else {
1271 ASSERT(db->db_level+1 == dn->dn_nlevels);
1272 ASSERT(db->db_blkid < dn->dn_nblkptr);
1273 ASSERT(db->db_parent == NULL || db->db_parent == dn->dn_dbuf);
1274 mutex_enter(&dn->dn_mtx);
1275 ASSERT(!list_link_active(&dr->dr_dirty_node));
1276 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1277 mutex_exit(&dn->dn_mtx);
1278 if (drop_struct_lock)
1279 rw_exit(&dn->dn_struct_rwlock);
1280 }
1281
1282 dnode_setdirty(dn, tx);
1283 DB_DNODE_EXIT(db);
1284 return (dr);
1285 }
1286
1287 static int
1288 dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1289 {
1290 dnode_t *dn;
1291 uint64_t txg = tx->tx_txg;
1292 dbuf_dirty_record_t *dr, **drp;
1293
1294 ASSERT(txg != 0);
1295 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1296
1297 mutex_enter(&db->db_mtx);
1298 /*
1299 * If this buffer is not dirty, we're done.
1300 */
1301 for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next)
1302 if (dr->dr_txg <= txg)
1303 break;
1304 if (dr == NULL || dr->dr_txg < txg) {
1305 mutex_exit(&db->db_mtx);
1306 return (0);
1307 }
1308 ASSERT(dr->dr_txg == txg);
1309 ASSERT(dr->dr_dbuf == db);
1310
1311 DB_DNODE_ENTER(db);
1312 dn = DB_DNODE(db);
1313
1314 /*
1315 * If this buffer is currently held, we cannot undirty
1316 * it, since one of the current holders may be in the
1317 * middle of an update. Note that users of dbuf_undirty()
1318 * should not place a hold on the dbuf before the call.
1319 * Also note: we can get here with a spill block, so
1320 * test for that similar to how dbuf_dirty does.
1321 */
1322 if (refcount_count(&db->db_holds) > db->db_dirtycnt) {
1323 mutex_exit(&db->db_mtx);
1324 /* Make sure we don't toss this buffer at sync phase */
1325 if (db->db_blkid != DMU_SPILL_BLKID) {
1326 mutex_enter(&dn->dn_mtx);
1327 dnode_clear_range(dn, db->db_blkid, 1, tx);
1328 mutex_exit(&dn->dn_mtx);
1329 }
1330 DB_DNODE_EXIT(db);
1331 return (0);
1332 }
1333
1334 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1335
1336 ASSERT(db->db.db_size != 0);
1337
1338 /* XXX would be nice to fix up dn_towrite_space[] */
1339
1340 *drp = dr->dr_next;
1341
1342 /*
1343 * Note that there are three places in dbuf_dirty()
1344 * where this dirty record may be put on a list.
1345 * Make sure to do a list_remove corresponding to
1346 * every one of those list_insert calls.
1347 */
1348 if (dr->dr_parent) {
1349 mutex_enter(&dr->dr_parent->dt.di.dr_mtx);
1350 list_remove(&dr->dr_parent->dt.di.dr_children, dr);
1351 mutex_exit(&dr->dr_parent->dt.di.dr_mtx);
1352 } else if (db->db_blkid == DMU_SPILL_BLKID ||
1353 db->db_level+1 == dn->dn_nlevels) {
1354 ASSERT(db->db_blkptr == NULL || db->db_parent == dn->dn_dbuf);
1355 mutex_enter(&dn->dn_mtx);
1356 list_remove(&dn->dn_dirty_records[txg & TXG_MASK], dr);
1357 mutex_exit(&dn->dn_mtx);
1358 }
1359 DB_DNODE_EXIT(db);
1360
1361 if (db->db_level == 0) {
1362 if (db->db_state != DB_NOFILL) {
1363 dbuf_unoverride(dr);
1364
1365 ASSERT(db->db_buf != NULL);
1366 ASSERT(dr->dt.dl.dr_data != NULL);
1367 if (dr->dt.dl.dr_data != db->db_buf)
1368 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data,
1369 db) == 1);
1370 }
1371 } else {
1372 ASSERT(db->db_buf != NULL);
1373 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
1374 mutex_destroy(&dr->dt.di.dr_mtx);
1375 list_destroy(&dr->dt.di.dr_children);
1376 }
1377 kmem_free(dr, sizeof (dbuf_dirty_record_t));
1378
1379 ASSERT(db->db_dirtycnt > 0);
1380 db->db_dirtycnt -= 1;
1381
1382 if (refcount_remove(&db->db_holds, (void *)(uintptr_t)txg) == 0) {
1383 arc_buf_t *buf = db->db_buf;
1384
1385 ASSERT(db->db_state == DB_NOFILL || arc_released(buf));
1386 dbuf_set_data(db, NULL);
1387 VERIFY(arc_buf_remove_ref(buf, db) == 1);
1388 dbuf_evict(db);
1389 return (1);
1390 }
1391
1392 mutex_exit(&db->db_mtx);
1393 return (0);
1394 }
1395
1396 #pragma weak dmu_buf_will_dirty = dbuf_will_dirty
1397 void
1398 dbuf_will_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1399 {
1400 int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH;
1401
1402 ASSERT(tx->tx_txg != 0);
1403 ASSERT(!refcount_is_zero(&db->db_holds));
1404
1405 DB_DNODE_ENTER(db);
1406 if (RW_WRITE_HELD(&DB_DNODE(db)->dn_struct_rwlock))
1407 rf |= DB_RF_HAVESTRUCT;
1408 DB_DNODE_EXIT(db);
1409 (void) dbuf_read(db, NULL, rf);
1410 (void) dbuf_dirty(db, tx);
1411 }
1412
1413 void
1414 dmu_buf_will_not_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1415 {
1416 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1417
1418 db->db_state = DB_NOFILL;
1419
1420 dmu_buf_will_fill(db_fake, tx);
1421 }
1422
1423 void
1424 dmu_buf_will_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1425 {
1426 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1427
1428 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1429 ASSERT(tx->tx_txg != 0);
1430 ASSERT(db->db_level == 0);
1431 ASSERT(!refcount_is_zero(&db->db_holds));
1432
1433 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT ||
1434 dmu_tx_private_ok(tx));
1435
1436 dbuf_noread(db);
1437 (void) dbuf_dirty(db, tx);
1438 }
1439
1440 #pragma weak dmu_buf_fill_done = dbuf_fill_done
1441 /* ARGSUSED */
1442 void
1443 dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx)
1444 {
1445 mutex_enter(&db->db_mtx);
1446 DBUF_VERIFY(db);
1447
1448 if (db->db_state == DB_FILL) {
1449 if (db->db_level == 0 && db->db_freed_in_flight) {
1450 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1451 /* we were freed while filling */
1452 /* XXX dbuf_undirty? */
1453 bzero(db->db.db_data, db->db.db_size);
1454 db->db_freed_in_flight = FALSE;
1455 }
1456 db->db_state = DB_CACHED;
1457 cv_broadcast(&db->db_changed);
1458 }
1459 mutex_exit(&db->db_mtx);
1460 }
1461
1462 /*
1463 * Directly assign a provided arc buf to a given dbuf if it's not referenced
1464 * by anybody except our caller. Otherwise copy arcbuf's contents to dbuf.
1465 */
1466 void
1467 dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx)
1468 {
1469 ASSERT(!refcount_is_zero(&db->db_holds));
1470 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1471 ASSERT(db->db_level == 0);
1472 ASSERT(DBUF_GET_BUFC_TYPE(db) == ARC_BUFC_DATA);
1473 ASSERT(buf != NULL);
1474 ASSERT(arc_buf_size(buf) == db->db.db_size);
1475 ASSERT(tx->tx_txg != 0);
1476
1477 arc_return_buf(buf, db);
1478 ASSERT(arc_released(buf));
1479
1480 mutex_enter(&db->db_mtx);
1481
1482 while (db->db_state == DB_READ || db->db_state == DB_FILL)
1483 cv_wait(&db->db_changed, &db->db_mtx);
1484
1485 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED);
1486
1487 if (db->db_state == DB_CACHED &&
1488 refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) {
1489 mutex_exit(&db->db_mtx);
1490 (void) dbuf_dirty(db, tx);
1491 bcopy(buf->b_data, db->db.db_data, db->db.db_size);
1492 VERIFY(arc_buf_remove_ref(buf, db) == 1);
1493 xuio_stat_wbuf_copied();
1494 return;
1495 }
1496
1497 xuio_stat_wbuf_nocopy();
1498 if (db->db_state == DB_CACHED) {
1499 dbuf_dirty_record_t *dr = db->db_last_dirty;
1500
1501 ASSERT(db->db_buf != NULL);
1502 if (dr != NULL && dr->dr_txg == tx->tx_txg) {
1503 ASSERT(dr->dt.dl.dr_data == db->db_buf);
1504 if (!arc_released(db->db_buf)) {
1505 ASSERT(dr->dt.dl.dr_override_state ==
1506 DR_OVERRIDDEN);
1507 arc_release(db->db_buf, db);
1508 }
1509 dr->dt.dl.dr_data = buf;
1510 VERIFY(arc_buf_remove_ref(db->db_buf, db) == 1);
1511 } else if (dr == NULL || dr->dt.dl.dr_data != db->db_buf) {
1512 arc_release(db->db_buf, db);
1513 VERIFY(arc_buf_remove_ref(db->db_buf, db) == 1);
1514 }
1515 db->db_buf = NULL;
1516 }
1517 ASSERT(db->db_buf == NULL);
1518 dbuf_set_data(db, buf);
1519 db->db_state = DB_FILL;
1520 mutex_exit(&db->db_mtx);
1521 (void) dbuf_dirty(db, tx);
1522 dbuf_fill_done(db, tx);
1523 }
1524
1525 /*
1526 * "Clear" the contents of this dbuf. This will mark the dbuf
1527 * EVICTING and clear *most* of its references. Unfortunetely,
1528 * when we are not holding the dn_dbufs_mtx, we can't clear the
1529 * entry in the dn_dbufs list. We have to wait until dbuf_destroy()
1530 * in this case. For callers from the DMU we will usually see:
1531 * dbuf_clear()->arc_buf_evict()->dbuf_do_evict()->dbuf_destroy()
1532 * For the arc callback, we will usually see:
1533 * dbuf_do_evict()->dbuf_clear();dbuf_destroy()
1534 * Sometimes, though, we will get a mix of these two:
1535 * DMU: dbuf_clear()->arc_buf_evict()
1536 * ARC: dbuf_do_evict()->dbuf_destroy()
1537 */
1538 void
1539 dbuf_clear(dmu_buf_impl_t *db)
1540 {
1541 dnode_t *dn;
1542 dmu_buf_impl_t *parent = db->db_parent;
1543 dmu_buf_impl_t *dndb;
1544 int dbuf_gone = FALSE;
1545
1546 ASSERT(MUTEX_HELD(&db->db_mtx));
1547 ASSERT(refcount_is_zero(&db->db_holds));
1548
1549 dbuf_evict_user(db);
1550
1551 if (db->db_state == DB_CACHED) {
1552 ASSERT(db->db.db_data != NULL);
1553 if (db->db_blkid == DMU_BONUS_BLKID) {
1554 zio_buf_free(db->db.db_data, DN_MAX_BONUSLEN);
1555 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
1556 }
1557 db->db.db_data = NULL;
1558 db->db_state = DB_UNCACHED;
1559 }
1560
1561 ASSERT(db->db_state == DB_UNCACHED || db->db_state == DB_NOFILL);
1562 ASSERT(db->db_data_pending == NULL);
1563
1564 db->db_state = DB_EVICTING;
1565 db->db_blkptr = NULL;
1566
1567 DB_DNODE_ENTER(db);
1568 dn = DB_DNODE(db);
1569 dndb = dn->dn_dbuf;
1570 if (db->db_blkid != DMU_BONUS_BLKID && MUTEX_HELD(&dn->dn_dbufs_mtx)) {
1571 list_remove(&dn->dn_dbufs, db);
1572 (void) atomic_dec_32_nv(&dn->dn_dbufs_count);
1573 membar_producer();
1574 DB_DNODE_EXIT(db);
1575 /*
1576 * Decrementing the dbuf count means that the hold corresponding
1577 * to the removed dbuf is no longer discounted in dnode_move(),
1578 * so the dnode cannot be moved until after we release the hold.
1579 * The membar_producer() ensures visibility of the decremented
1580 * value in dnode_move(), since DB_DNODE_EXIT doesn't actually
1581 * release any lock.
1582 */
1583 dnode_rele(dn, db);
1584 db->db_dnode_handle = NULL;
1585 } else {
1586 DB_DNODE_EXIT(db);
1587 }
1588
1589 if (db->db_buf)
1590 dbuf_gone = arc_buf_evict(db->db_buf);
1591
1592 if (!dbuf_gone)
1593 mutex_exit(&db->db_mtx);
1594
1595 /*
1596 * If this dbuf is referenced from an indirect dbuf,
1597 * decrement the ref count on the indirect dbuf.
1598 */
1599 if (parent && parent != dndb)
1600 dbuf_rele(parent, db);
1601 }
1602
1603 static int
1604 dbuf_findbp(dnode_t *dn, int level, uint64_t blkid, int fail_sparse,
1605 dmu_buf_impl_t **parentp, blkptr_t **bpp)
1606 {
1607 int nlevels, epbs;
1608
1609 *parentp = NULL;
1610 *bpp = NULL;
1611
1612 ASSERT(blkid != DMU_BONUS_BLKID);
1613
1614 if (blkid == DMU_SPILL_BLKID) {
1615 mutex_enter(&dn->dn_mtx);
1616 if (dn->dn_have_spill &&
1617 (dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR))
1618 *bpp = &dn->dn_phys->dn_spill;
1619 else
1620 *bpp = NULL;
1621 dbuf_add_ref(dn->dn_dbuf, NULL);
1622 *parentp = dn->dn_dbuf;
1623 mutex_exit(&dn->dn_mtx);
1624 return (0);
1625 }
1626
1627 if (dn->dn_phys->dn_nlevels == 0)
1628 nlevels = 1;
1629 else
1630 nlevels = dn->dn_phys->dn_nlevels;
1631
1632 epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1633
1634 ASSERT3U(level * epbs, <, 64);
1635 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1636 if (level >= nlevels ||
1637 (blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))) {
1638 /* the buffer has no parent yet */
1639 return (ENOENT);
1640 } else if (level < nlevels-1) {
1641 /* this block is referenced from an indirect block */
1642 int err = dbuf_hold_impl(dn, level+1,
1643 blkid >> epbs, fail_sparse, NULL, parentp);
1644 if (err)
1645 return (err);
1646 err = dbuf_read(*parentp, NULL,
1647 (DB_RF_HAVESTRUCT | DB_RF_NOPREFETCH | DB_RF_CANFAIL));
1648 if (err) {
1649 dbuf_rele(*parentp, NULL);
1650 *parentp = NULL;
1651 return (err);
1652 }
1653 *bpp = ((blkptr_t *)(*parentp)->db.db_data) +
1654 (blkid & ((1ULL << epbs) - 1));
1655 return (0);
1656 } else {
1657 /* the block is referenced from the dnode */
1658 ASSERT3U(level, ==, nlevels-1);
1659 ASSERT(dn->dn_phys->dn_nblkptr == 0 ||
1660 blkid < dn->dn_phys->dn_nblkptr);
1661 if (dn->dn_dbuf) {
1662 dbuf_add_ref(dn->dn_dbuf, NULL);
1663 *parentp = dn->dn_dbuf;
1664 }
1665 *bpp = &dn->dn_phys->dn_blkptr[blkid];
1666 return (0);
1667 }
1668 }
1669
1670 static dmu_buf_impl_t *
1671 dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid,
1672 dmu_buf_impl_t *parent, blkptr_t *blkptr)
1673 {
1674 objset_t *os = dn->dn_objset;
1675 dmu_buf_impl_t *db, *odb;
1676
1677 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1678 ASSERT(dn->dn_type != DMU_OT_NONE);
1679
1680 db = kmem_cache_alloc(dbuf_cache, KM_SLEEP);
1681
1682 db->db_objset = os;
1683 db->db.db_object = dn->dn_object;
1684 db->db_level = level;
1685 db->db_blkid = blkid;
1686 db->db_last_dirty = NULL;
1687 db->db_dirtycnt = 0;
1688 db->db_dnode_handle = dn->dn_handle;
1689 db->db_parent = parent;
1690 db->db_blkptr = blkptr;
1691
1692 db->db_user_ptr = NULL;
1693 db->db_user_data_ptr_ptr = NULL;
1694 db->db_evict_func = NULL;
1695 db->db_immediate_evict = 0;
1696 db->db_freed_in_flight = 0;
1697
1698 if (blkid == DMU_BONUS_BLKID) {
1699 ASSERT3P(parent, ==, dn->dn_dbuf);
1700 db->db.db_size = DN_MAX_BONUSLEN -
1701 (dn->dn_nblkptr-1) * sizeof (blkptr_t);
1702 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
1703 db->db.db_offset = DMU_BONUS_BLKID;
1704 db->db_state = DB_UNCACHED;
1705 /* the bonus dbuf is not placed in the hash table */
1706 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1707 return (db);
1708 } else if (blkid == DMU_SPILL_BLKID) {
1709 db->db.db_size = (blkptr != NULL) ?
1710 BP_GET_LSIZE(blkptr) : SPA_MINBLOCKSIZE;
1711 db->db.db_offset = 0;
1712 } else {
1713 int blocksize =
1714 db->db_level ? 1<<dn->dn_indblkshift : dn->dn_datablksz;
1715 db->db.db_size = blocksize;
1716 db->db.db_offset = db->db_blkid * blocksize;
1717 }
1718
1719 /*
1720 * Hold the dn_dbufs_mtx while we get the new dbuf
1721 * in the hash table *and* added to the dbufs list.
1722 * This prevents a possible deadlock with someone
1723 * trying to look up this dbuf before its added to the
1724 * dn_dbufs list.
1725 */
1726 mutex_enter(&dn->dn_dbufs_mtx);
1727 db->db_state = DB_EVICTING;
1728 if ((odb = dbuf_hash_insert(db)) != NULL) {
1729 /* someone else inserted it first */
1730 kmem_cache_free(dbuf_cache, db);
1731 mutex_exit(&dn->dn_dbufs_mtx);
1732 return (odb);
1733 }
1734 list_insert_head(&dn->dn_dbufs, db);
1735 db->db_state = DB_UNCACHED;
1736 mutex_exit(&dn->dn_dbufs_mtx);
1737 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1738
1739 if (parent && parent != dn->dn_dbuf)
1740 dbuf_add_ref(parent, db);
1741
1742 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1743 refcount_count(&dn->dn_holds) > 0);
1744 (void) refcount_add(&dn->dn_holds, db);
1745 (void) atomic_inc_32_nv(&dn->dn_dbufs_count);
1746
1747 dprintf_dbuf(db, "db=%p\n", db);
1748
1749 return (db);
1750 }
1751
1752 static int
1753 dbuf_do_evict(void *private)
1754 {
1755 arc_buf_t *buf = private;
1756 dmu_buf_impl_t *db = buf->b_private;
1757
1758 if (!MUTEX_HELD(&db->db_mtx))
1759 mutex_enter(&db->db_mtx);
1760
1761 ASSERT(refcount_is_zero(&db->db_holds));
1762
1763 if (db->db_state != DB_EVICTING) {
1764 ASSERT(db->db_state == DB_CACHED);
1765 DBUF_VERIFY(db);
1766 db->db_buf = NULL;
1767 dbuf_evict(db);
1768 } else {
1769 mutex_exit(&db->db_mtx);
1770 dbuf_destroy(db);
1771 }
1772 return (0);
1773 }
1774
1775 static void
1776 dbuf_destroy(dmu_buf_impl_t *db)
1777 {
1778 ASSERT(refcount_is_zero(&db->db_holds));
1779
1780 if (db->db_blkid != DMU_BONUS_BLKID) {
1781 /*
1782 * If this dbuf is still on the dn_dbufs list,
1783 * remove it from that list.
1784 */
1785 if (db->db_dnode_handle != NULL) {
1786 dnode_t *dn;
1787
1788 DB_DNODE_ENTER(db);
1789 dn = DB_DNODE(db);
1790 mutex_enter(&dn->dn_dbufs_mtx);
1791 list_remove(&dn->dn_dbufs, db);
1792 (void) atomic_dec_32_nv(&dn->dn_dbufs_count);
1793 mutex_exit(&dn->dn_dbufs_mtx);
1794 DB_DNODE_EXIT(db);
1795 /*
1796 * Decrementing the dbuf count means that the hold
1797 * corresponding to the removed dbuf is no longer
1798 * discounted in dnode_move(), so the dnode cannot be
1799 * moved until after we release the hold.
1800 */
1801 dnode_rele(dn, db);
1802 db->db_dnode_handle = NULL;
1803 }
1804 dbuf_hash_remove(db);
1805 }
1806 db->db_parent = NULL;
1807 db->db_buf = NULL;
1808
1809 ASSERT(!list_link_active(&db->db_link));
1810 ASSERT(db->db.db_data == NULL);
1811 ASSERT(db->db_hash_next == NULL);
1812 ASSERT(db->db_blkptr == NULL);
1813 ASSERT(db->db_data_pending == NULL);
1814
1815 kmem_cache_free(dbuf_cache, db);
1816 arc_space_return(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1817 }
1818
1819 void
1820 dbuf_prefetch(dnode_t *dn, uint64_t blkid)
1821 {
1822 dmu_buf_impl_t *db = NULL;
1823 blkptr_t *bp = NULL;
1824
1825 ASSERT(blkid != DMU_BONUS_BLKID);
1826 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1827
1828 if (dnode_block_freed(dn, blkid))
1829 return;
1830
1831 /* dbuf_find() returns with db_mtx held */
1832 if (db = dbuf_find(dn, 0, blkid)) {
1833 /*
1834 * This dbuf is already in the cache. We assume that
1835 * it is already CACHED, or else about to be either
1836 * read or filled.
1837 */
1838 mutex_exit(&db->db_mtx);
1839 return;
1840 }
1841
1842 if (dbuf_findbp(dn, 0, blkid, TRUE, &db, &bp) == 0) {
1843 if (bp && !BP_IS_HOLE(bp)) {
1844 int priority = dn->dn_type == DMU_OT_DDT_ZAP ?
1845 ZIO_PRIORITY_DDT_PREFETCH : ZIO_PRIORITY_ASYNC_READ;
1846 arc_buf_t *pbuf;
1847 dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset;
1848 uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH;
1849 zbookmark_t zb;
1850
1851 SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
1852 dn->dn_object, 0, blkid);
1853
1854 if (db)
1855 pbuf = db->db_buf;
1856 else
1857 pbuf = dn->dn_objset->os_phys_buf;
1858
1859 (void) dsl_read(NULL, dn->dn_objset->os_spa,
1860 bp, pbuf, NULL, NULL, priority,
1861 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
1862 &aflags, &zb);
1863 }
1864 if (db)
1865 dbuf_rele(db, NULL);
1866 }
1867 }
1868
1869 /*
1870 * Returns with db_holds incremented, and db_mtx not held.
1871 * Note: dn_struct_rwlock must be held.
1872 */
1873 int
1874 dbuf_hold_impl(dnode_t *dn, uint8_t level, uint64_t blkid, int fail_sparse,
1875 void *tag, dmu_buf_impl_t **dbp)
1876 {
1877 dmu_buf_impl_t *db, *parent = NULL;
1878
1879 ASSERT(blkid != DMU_BONUS_BLKID);
1880 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1881 ASSERT3U(dn->dn_nlevels, >, level);
1882
1883 *dbp = NULL;
1884 top:
1885 /* dbuf_find() returns with db_mtx held */
1886 db = dbuf_find(dn, level, blkid);
1887
1888 if (db == NULL) {
1889 blkptr_t *bp = NULL;
1890 int err;
1891
1892 ASSERT3P(parent, ==, NULL);
1893 err = dbuf_findbp(dn, level, blkid, fail_sparse, &parent, &bp);
1894 if (fail_sparse) {
1895 if (err == 0 && bp && BP_IS_HOLE(bp))
1896 err = ENOENT;
1897 if (err) {
1898 if (parent)
1899 dbuf_rele(parent, NULL);
1900 return (err);
1901 }
1902 }
1903 if (err && err != ENOENT)
1904 return (err);
1905 db = dbuf_create(dn, level, blkid, parent, bp);
1906 }
1907
1908 if (db->db_buf && refcount_is_zero(&db->db_holds)) {
1909 arc_buf_add_ref(db->db_buf, db);
1910 if (db->db_buf->b_data == NULL) {
1911 dbuf_clear(db);
1912 if (parent) {
1913 dbuf_rele(parent, NULL);
1914 parent = NULL;
1915 }
1916 goto top;
1917 }
1918 ASSERT3P(db->db.db_data, ==, db->db_buf->b_data);
1919 }
1920
1921 ASSERT(db->db_buf == NULL || arc_referenced(db->db_buf));
1922
1923 /*
1924 * If this buffer is currently syncing out, and we are are
1925 * still referencing it from db_data, we need to make a copy
1926 * of it in case we decide we want to dirty it again in this txg.
1927 */
1928 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
1929 dn->dn_object != DMU_META_DNODE_OBJECT &&
1930 db->db_state == DB_CACHED && db->db_data_pending) {
1931 dbuf_dirty_record_t *dr = db->db_data_pending;
1932
1933 if (dr->dt.dl.dr_data == db->db_buf) {
1934 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
1935
1936 dbuf_set_data(db,
1937 arc_buf_alloc(dn->dn_objset->os_spa,
1938 db->db.db_size, db, type));
1939 bcopy(dr->dt.dl.dr_data->b_data, db->db.db_data,
1940 db->db.db_size);
1941 }
1942 }
1943
1944 (void) refcount_add(&db->db_holds, tag);
1945 dbuf_update_data(db);
1946 DBUF_VERIFY(db);
1947 mutex_exit(&db->db_mtx);
1948
1949 /* NOTE: we can't rele the parent until after we drop the db_mtx */
1950 if (parent)
1951 dbuf_rele(parent, NULL);
1952
1953 ASSERT3P(DB_DNODE(db), ==, dn);
1954 ASSERT3U(db->db_blkid, ==, blkid);
1955 ASSERT3U(db->db_level, ==, level);
1956 *dbp = db;
1957
1958 return (0);
1959 }
1960
1961 dmu_buf_impl_t *
1962 dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag)
1963 {
1964 dmu_buf_impl_t *db;
1965 int err = dbuf_hold_impl(dn, 0, blkid, FALSE, tag, &db);
1966 return (err ? NULL : db);
1967 }
1968
1969 dmu_buf_impl_t *
1970 dbuf_hold_level(dnode_t *dn, int level, uint64_t blkid, void *tag)
1971 {
1972 dmu_buf_impl_t *db;
1973 int err = dbuf_hold_impl(dn, level, blkid, FALSE, tag, &db);
1974 return (err ? NULL : db);
1975 }
1976
1977 void
1978 dbuf_create_bonus(dnode_t *dn)
1979 {
1980 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
1981
1982 ASSERT(dn->dn_bonus == NULL);
1983 dn->dn_bonus = dbuf_create(dn, 0, DMU_BONUS_BLKID, dn->dn_dbuf, NULL);
1984 }
1985
1986 int
1987 dbuf_spill_set_blksz(dmu_buf_t *db_fake, uint64_t blksz, dmu_tx_t *tx)
1988 {
1989 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1990 dnode_t *dn;
1991
1992 if (db->db_blkid != DMU_SPILL_BLKID)
1993 return (ENOTSUP);
1994 if (blksz == 0)
1995 blksz = SPA_MINBLOCKSIZE;
1996 if (blksz > SPA_MAXBLOCKSIZE)
1997 blksz = SPA_MAXBLOCKSIZE;
1998 else
1999 blksz = P2ROUNDUP(blksz, SPA_MINBLOCKSIZE);
2000
2001 DB_DNODE_ENTER(db);
2002 dn = DB_DNODE(db);
2003 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
2004 dbuf_new_size(db, blksz, tx);
2005 rw_exit(&dn->dn_struct_rwlock);
2006 DB_DNODE_EXIT(db);
2007
2008 return (0);
2009 }
2010
2011 void
2012 dbuf_rm_spill(dnode_t *dn, dmu_tx_t *tx)
2013 {
2014 dbuf_free_range(dn, DMU_SPILL_BLKID, DMU_SPILL_BLKID, tx);
2015 }
2016
2017 #pragma weak dmu_buf_add_ref = dbuf_add_ref
2018 void
2019 dbuf_add_ref(dmu_buf_impl_t *db, void *tag)
2020 {
2021 int64_t holds = refcount_add(&db->db_holds, tag);
2022 ASSERT(holds > 1);
2023 }
2024
2025 /*
2026 * If you call dbuf_rele() you had better not be referencing the dnode handle
2027 * unless you have some other direct or indirect hold on the dnode. (An indirect
2028 * hold is a hold on one of the dnode's dbufs, including the bonus buffer.)
2029 * Without that, the dbuf_rele() could lead to a dnode_rele() followed by the
2030 * dnode's parent dbuf evicting its dnode handles.
2031 */
2032 #pragma weak dmu_buf_rele = dbuf_rele
2033 void
2034 dbuf_rele(dmu_buf_impl_t *db, void *tag)
2035 {
2036 mutex_enter(&db->db_mtx);
2037 dbuf_rele_and_unlock(db, tag);
2038 }
2039
2040 /*
2041 * dbuf_rele() for an already-locked dbuf. This is necessary to allow
2042 * db_dirtycnt and db_holds to be updated atomically.
2043 */
2044 void
2045 dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag)
2046 {
2047 int64_t holds;
2048
2049 ASSERT(MUTEX_HELD(&db->db_mtx));
2050 DBUF_VERIFY(db);
2051
2052 /*
2053 * Remove the reference to the dbuf before removing its hold on the
2054 * dnode so we can guarantee in dnode_move() that a referenced bonus
2055 * buffer has a corresponding dnode hold.
2056 */
2057 holds = refcount_remove(&db->db_holds, tag);
2058 ASSERT(holds >= 0);
2059
2060 /*
2061 * We can't freeze indirects if there is a possibility that they
2062 * may be modified in the current syncing context.
2063 */
2064 if (db->db_buf && holds == (db->db_level == 0 ? db->db_dirtycnt : 0))
2065 arc_buf_freeze(db->db_buf);
2066
2067 if (holds == db->db_dirtycnt &&
2068 db->db_level == 0 && db->db_immediate_evict)
2069 dbuf_evict_user(db);
2070
2071 if (holds == 0) {
2072 if (db->db_blkid == DMU_BONUS_BLKID) {
2073 mutex_exit(&db->db_mtx);
2074
2075 /*
2076 * If the dnode moves here, we cannot cross this barrier
2077 * until the move completes.
2078 */
2079 DB_DNODE_ENTER(db);
2080 (void) atomic_dec_32_nv(&DB_DNODE(db)->dn_dbufs_count);
2081 DB_DNODE_EXIT(db);
2082 /*
2083 * The bonus buffer's dnode hold is no longer discounted
2084 * in dnode_move(). The dnode cannot move until after
2085 * the dnode_rele().
2086 */
2087 dnode_rele(DB_DNODE(db), db);
2088 } else if (db->db_buf == NULL) {
2089 /*
2090 * This is a special case: we never associated this
2091 * dbuf with any data allocated from the ARC.
2092 */
2093 ASSERT(db->db_state == DB_UNCACHED ||
2094 db->db_state == DB_NOFILL);
2095 dbuf_evict(db);
2096 } else if (arc_released(db->db_buf)) {
2097 arc_buf_t *buf = db->db_buf;
2098 /*
2099 * This dbuf has anonymous data associated with it.
2100 */
2101 dbuf_set_data(db, NULL);
2102 VERIFY(arc_buf_remove_ref(buf, db) == 1);
2103 dbuf_evict(db);
2104 } else {
2105 VERIFY(arc_buf_remove_ref(db->db_buf, db) == 0);
2106
2107 /*
2108 * A dbuf will be eligible for eviction if either the
2109 * 'primarycache' property is set or a duplicate
2110 * copy of this buffer is already cached in the arc.
2111 *
2112 * In the case of the 'primarycache' a buffer
2113 * is considered for eviction if it matches the
2114 * criteria set in the property.
2115 *
2116 * To decide if our buffer is considered a
2117 * duplicate, we must call into the arc to determine
2118 * if multiple buffers are referencing the same
2119 * block on-disk. If so, then we simply evict
2120 * ourselves.
2121 */
2122 if (!DBUF_IS_CACHEABLE(db) ||
2123 arc_buf_eviction_needed(db->db_buf))
2124 dbuf_clear(db);
2125 else
2126 mutex_exit(&db->db_mtx);
2127 }
2128 } else {
2129 mutex_exit(&db->db_mtx);
2130 }
2131 }
2132
2133 #pragma weak dmu_buf_refcount = dbuf_refcount
2134 uint64_t
2135 dbuf_refcount(dmu_buf_impl_t *db)
2136 {
2137 return (refcount_count(&db->db_holds));
2138 }
2139
2140 void *
2141 dmu_buf_set_user(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr,
2142 dmu_buf_evict_func_t *evict_func)
2143 {
2144 return (dmu_buf_update_user(db_fake, NULL, user_ptr,
2145 user_data_ptr_ptr, evict_func));
2146 }
2147
2148 void *
2149 dmu_buf_set_user_ie(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr,
2150 dmu_buf_evict_func_t *evict_func)
2151 {
2152 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2153
2154 db->db_immediate_evict = TRUE;
2155 return (dmu_buf_update_user(db_fake, NULL, user_ptr,
2156 user_data_ptr_ptr, evict_func));
2157 }
2158
2159 void *
2160 dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr, void *user_ptr,
2161 void *user_data_ptr_ptr, dmu_buf_evict_func_t *evict_func)
2162 {
2163 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2164 ASSERT(db->db_level == 0);
2165
2166 ASSERT((user_ptr == NULL) == (evict_func == NULL));
2167
2168 mutex_enter(&db->db_mtx);
2169
2170 if (db->db_user_ptr == old_user_ptr) {
2171 db->db_user_ptr = user_ptr;
2172 db->db_user_data_ptr_ptr = user_data_ptr_ptr;
2173 db->db_evict_func = evict_func;
2174
2175 dbuf_update_data(db);
2176 } else {
2177 old_user_ptr = db->db_user_ptr;
2178 }
2179
2180 mutex_exit(&db->db_mtx);
2181 return (old_user_ptr);
2182 }
2183
2184 void *
2185 dmu_buf_get_user(dmu_buf_t *db_fake)
2186 {
2187 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2188 ASSERT(!refcount_is_zero(&db->db_holds));
2189
2190 return (db->db_user_ptr);
2191 }
2192
2193 boolean_t
2194 dmu_buf_freeable(dmu_buf_t *dbuf)
2195 {
2196 boolean_t res = B_FALSE;
2197 dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf;
2198
2199 if (db->db_blkptr)
2200 res = dsl_dataset_block_freeable(db->db_objset->os_dsl_dataset,
2201 db->db_blkptr, db->db_blkptr->blk_birth);
2202
2203 return (res);
2204 }
2205
2206 blkptr_t *
2207 dmu_buf_get_blkptr(dmu_buf_t *db)
2208 {
2209 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
2210 return (dbi->db_blkptr);
2211 }
2212
2213 static void
2214 dbuf_check_blkptr(dnode_t *dn, dmu_buf_impl_t *db)
2215 {
2216 /* ASSERT(dmu_tx_is_syncing(tx) */
2217 ASSERT(MUTEX_HELD(&db->db_mtx));
2218
2219 if (db->db_blkptr != NULL)
2220 return;
2221
2222 if (db->db_blkid == DMU_SPILL_BLKID) {
2223 db->db_blkptr = &dn->dn_phys->dn_spill;
2224 BP_ZERO(db->db_blkptr);
2225 return;
2226 }
2227 if (db->db_level == dn->dn_phys->dn_nlevels-1) {
2228 /*
2229 * This buffer was allocated at a time when there was
2230 * no available blkptrs from the dnode, or it was
2231 * inappropriate to hook it in (i.e., nlevels mis-match).
2232 */
2233 ASSERT(db->db_blkid < dn->dn_phys->dn_nblkptr);
2234 ASSERT(db->db_parent == NULL);
2235 db->db_parent = dn->dn_dbuf;
2236 db->db_blkptr = &dn->dn_phys->dn_blkptr[db->db_blkid];
2237 DBUF_VERIFY(db);
2238 } else {
2239 dmu_buf_impl_t *parent = db->db_parent;
2240 int epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2241
2242 ASSERT(dn->dn_phys->dn_nlevels > 1);
2243 if (parent == NULL) {
2244 mutex_exit(&db->db_mtx);
2245 rw_enter(&dn->dn_struct_rwlock, RW_READER);
2246 (void) dbuf_hold_impl(dn, db->db_level+1,
2247 db->db_blkid >> epbs, FALSE, db, &parent);
2248 rw_exit(&dn->dn_struct_rwlock);
2249 mutex_enter(&db->db_mtx);
2250 db->db_parent = parent;
2251 }
2252 db->db_blkptr = (blkptr_t *)parent->db.db_data +
2253 (db->db_blkid & ((1ULL << epbs) - 1));
2254 DBUF_VERIFY(db);
2255 }
2256 }
2257
2258 static void
2259 dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
2260 {
2261 dmu_buf_impl_t *db = dr->dr_dbuf;
2262 dnode_t *dn;
2263 zio_t *zio;
2264
2265 ASSERT(dmu_tx_is_syncing(tx));
2266
2267 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
2268
2269 mutex_enter(&db->db_mtx);
2270
2271 ASSERT(db->db_level > 0);
2272 DBUF_VERIFY(db);
2273
2274 if (db->db_buf == NULL) {
2275 mutex_exit(&db->db_mtx);
2276 (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED);
2277 mutex_enter(&db->db_mtx);
2278 }
2279 ASSERT3U(db->db_state, ==, DB_CACHED);
2280 ASSERT(db->db_buf != NULL);
2281
2282 DB_DNODE_ENTER(db);
2283 dn = DB_DNODE(db);
2284 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2285 dbuf_check_blkptr(dn, db);
2286 DB_DNODE_EXIT(db);
2287
2288 db->db_data_pending = dr;
2289
2290 mutex_exit(&db->db_mtx);
2291 dbuf_write(dr, db->db_buf, tx);
2292
2293 zio = dr->dr_zio;
2294 mutex_enter(&dr->dt.di.dr_mtx);
2295 dbuf_sync_list(&dr->dt.di.dr_children, tx);
2296 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
2297 mutex_exit(&dr->dt.di.dr_mtx);
2298 zio_nowait(zio);
2299 }
2300
2301 static void
2302 dbuf_sync_leaf(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
2303 {
2304 arc_buf_t **datap = &dr->dt.dl.dr_data;
2305 dmu_buf_impl_t *db = dr->dr_dbuf;
2306 dnode_t *dn;
2307 objset_t *os;
2308 uint64_t txg = tx->tx_txg;
2309
2310 ASSERT(dmu_tx_is_syncing(tx));
2311
2312 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
2313
2314 mutex_enter(&db->db_mtx);
2315 /*
2316 * To be synced, we must be dirtied. But we
2317 * might have been freed after the dirty.
2318 */
2319 if (db->db_state == DB_UNCACHED) {
2320 /* This buffer has been freed since it was dirtied */
2321 ASSERT(db->db.db_data == NULL);
2322 } else if (db->db_state == DB_FILL) {
2323 /* This buffer was freed and is now being re-filled */
2324 ASSERT(db->db.db_data != dr->dt.dl.dr_data);
2325 } else {
2326 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_NOFILL);
2327 }
2328 DBUF_VERIFY(db);
2329
2330 DB_DNODE_ENTER(db);
2331 dn = DB_DNODE(db);
2332
2333 if (db->db_blkid == DMU_SPILL_BLKID) {
2334 mutex_enter(&dn->dn_mtx);
2335 dn->dn_phys->dn_flags |= DNODE_FLAG_SPILL_BLKPTR;
2336 mutex_exit(&dn->dn_mtx);
2337 }
2338
2339 /*
2340 * If this is a bonus buffer, simply copy the bonus data into the
2341 * dnode. It will be written out when the dnode is synced (and it
2342 * will be synced, since it must have been dirty for dbuf_sync to
2343 * be called).
2344 */
2345 if (db->db_blkid == DMU_BONUS_BLKID) {
2346 dbuf_dirty_record_t **drp;
2347
2348 ASSERT(*datap != NULL);
2349 ASSERT0(db->db_level);
2350 ASSERT3U(dn->dn_phys->dn_bonuslen, <=, DN_MAX_BONUSLEN);
2351 bcopy(*datap, DN_BONUS(dn->dn_phys), dn->dn_phys->dn_bonuslen);
2352 DB_DNODE_EXIT(db);
2353
2354 if (*datap != db->db.db_data) {
2355 zio_buf_free(*datap, DN_MAX_BONUSLEN);
2356 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
2357 }
2358 db->db_data_pending = NULL;
2359 drp = &db->db_last_dirty;
2360 while (*drp != dr)
2361 drp = &(*drp)->dr_next;
2362 ASSERT(dr->dr_next == NULL);
2363 ASSERT(dr->dr_dbuf == db);
2364 *drp = dr->dr_next;
2365 kmem_free(dr, sizeof (dbuf_dirty_record_t));
2366 ASSERT(db->db_dirtycnt > 0);
2367 db->db_dirtycnt -= 1;
2368 dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg);
2369 return;
2370 }
2371
2372 os = dn->dn_objset;
2373
2374 /*
2375 * This function may have dropped the db_mtx lock allowing a dmu_sync
2376 * operation to sneak in. As a result, we need to ensure that we
2377 * don't check the dr_override_state until we have returned from
2378 * dbuf_check_blkptr.
2379 */
2380 dbuf_check_blkptr(dn, db);
2381
2382 /*
2383 * If this buffer is in the middle of an immediate write,
2384 * wait for the synchronous IO to complete.
2385 */
2386 while (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC) {
2387 ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
2388 cv_wait(&db->db_changed, &db->db_mtx);
2389 ASSERT(dr->dt.dl.dr_override_state != DR_NOT_OVERRIDDEN);
2390 }
2391
2392 if (db->db_state != DB_NOFILL &&
2393 dn->dn_object != DMU_META_DNODE_OBJECT &&
2394 refcount_count(&db->db_holds) > 1 &&
2395 dr->dt.dl.dr_override_state != DR_OVERRIDDEN &&
2396 *datap == db->db_buf) {
2397 /*
2398 * If this buffer is currently "in use" (i.e., there
2399 * are active holds and db_data still references it),
2400 * then make a copy before we start the write so that
2401 * any modifications from the open txg will not leak
2402 * into this write.
2403 *
2404 * NOTE: this copy does not need to be made for
2405 * objects only modified in the syncing context (e.g.
2406 * DNONE_DNODE blocks).
2407 */
2408 int blksz = arc_buf_size(*datap);
2409 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
2410 *datap = arc_buf_alloc(os->os_spa, blksz, db, type);
2411 bcopy(db->db.db_data, (*datap)->b_data, blksz);
2412 }
2413 db->db_data_pending = dr;
2414
2415 mutex_exit(&db->db_mtx);
2416
2417 dbuf_write(dr, *datap, tx);
2418
2419 ASSERT(!list_link_active(&dr->dr_dirty_node));
2420 if (dn->dn_object == DMU_META_DNODE_OBJECT) {
2421 list_insert_tail(&dn->dn_dirty_records[txg&TXG_MASK], dr);
2422 DB_DNODE_EXIT(db);
2423 } else {
2424 /*
2425 * Although zio_nowait() does not "wait for an IO", it does
2426 * initiate the IO. If this is an empty write it seems plausible
2427 * that the IO could actually be completed before the nowait
2428 * returns. We need to DB_DNODE_EXIT() first in case
2429 * zio_nowait() invalidates the dbuf.
2430 */
2431 DB_DNODE_EXIT(db);
2432 zio_nowait(dr->dr_zio);
2433 }
2434 }
2435
2436 void
2437 dbuf_sync_list(list_t *list, dmu_tx_t *tx)
2438 {
2439 dbuf_dirty_record_t *dr;
2440
2441 while (dr = list_head(list)) {
2442 if (dr->dr_zio != NULL) {
2443 /*
2444 * If we find an already initialized zio then we
2445 * are processing the meta-dnode, and we have finished.
2446 * The dbufs for all dnodes are put back on the list
2447 * during processing, so that we can zio_wait()
2448 * these IOs after initiating all child IOs.
2449 */
2450 ASSERT3U(dr->dr_dbuf->db.db_object, ==,
2451 DMU_META_DNODE_OBJECT);
2452 break;
2453 }
2454 list_remove(list, dr);
2455 if (dr->dr_dbuf->db_level > 0)
2456 dbuf_sync_indirect(dr, tx);
2457 else
2458 dbuf_sync_leaf(dr, tx);
2459 }
2460 }
2461
2462 /* ARGSUSED */
2463 static void
2464 dbuf_write_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
2465 {
2466 dmu_buf_impl_t *db = vdb;
2467 dnode_t *dn;
2468 blkptr_t *bp = zio->io_bp;
2469 blkptr_t *bp_orig = &zio->io_bp_orig;
2470 spa_t *spa = zio->io_spa;
2471 int64_t delta;
2472 uint64_t fill = 0;
2473 int i;
2474
2475 ASSERT(db->db_blkptr == bp);
2476
2477 DB_DNODE_ENTER(db);
2478 dn = DB_DNODE(db);
2479 delta = bp_get_dsize_sync(spa, bp) - bp_get_dsize_sync(spa, bp_orig);
2480 dnode_diduse_space(dn, delta - zio->io_prev_space_delta);
2481 zio->io_prev_space_delta = delta;
2482
2483 if (BP_IS_HOLE(bp)) {
2484 ASSERT(bp->blk_fill == 0);
2485 DB_DNODE_EXIT(db);
2486 return;
2487 }
2488
2489 ASSERT((db->db_blkid != DMU_SPILL_BLKID &&
2490 BP_GET_TYPE(bp) == dn->dn_type) ||
2491 (db->db_blkid == DMU_SPILL_BLKID &&
2492 BP_GET_TYPE(bp) == dn->dn_bonustype));
2493 ASSERT(BP_GET_LEVEL(bp) == db->db_level);
2494
2495 mutex_enter(&db->db_mtx);
2496
2497 #ifdef ZFS_DEBUG
2498 if (db->db_blkid == DMU_SPILL_BLKID) {
2499 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
2500 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
2501 db->db_blkptr == &dn->dn_phys->dn_spill);
2502 }
2503 #endif
2504
2505 if (db->db_level == 0) {
2506 mutex_enter(&dn->dn_mtx);
2507 if (db->db_blkid > dn->dn_phys->dn_maxblkid &&
2508 db->db_blkid != DMU_SPILL_BLKID)
2509 dn->dn_phys->dn_maxblkid = db->db_blkid;
2510 mutex_exit(&dn->dn_mtx);
2511
2512 if (dn->dn_type == DMU_OT_DNODE) {
2513 dnode_phys_t *dnp = db->db.db_data;
2514 for (i = db->db.db_size >> DNODE_SHIFT; i > 0;
2515 i--, dnp++) {
2516 if (dnp->dn_type != DMU_OT_NONE)
2517 fill++;
2518 }
2519 } else {
2520 fill = 1;
2521 }
2522 } else {
2523 blkptr_t *ibp = db->db.db_data;
2524 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2525 for (i = db->db.db_size >> SPA_BLKPTRSHIFT; i > 0; i--, ibp++) {
2526 if (BP_IS_HOLE(ibp))
2527 continue;
2528 fill += ibp->blk_fill;
2529 }
2530 }
2531 DB_DNODE_EXIT(db);
2532
2533 bp->blk_fill = fill;
2534
2535 mutex_exit(&db->db_mtx);
2536 }
2537
2538 /* ARGSUSED */
2539 static void
2540 dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb)
2541 {
2542 dmu_buf_impl_t *db = vdb;
2543 blkptr_t *bp = zio->io_bp;
2544 blkptr_t *bp_orig = &zio->io_bp_orig;
2545 uint64_t txg = zio->io_txg;
2546 dbuf_dirty_record_t **drp, *dr;
2547
2548 ASSERT0(zio->io_error);
2549 ASSERT(db->db_blkptr == bp);
2550
2551 /*
2552 * For nopwrites and rewrites we ensure that the bp matches our
2553 * original and bypass all the accounting.
2554 */
2555 if (zio->io_flags & (ZIO_FLAG_IO_REWRITE | ZIO_FLAG_NOPWRITE)) {
2556 ASSERT(BP_EQUAL(bp, bp_orig));
2557 } else {
2558 objset_t *os;
2559 dsl_dataset_t *ds;
2560 dmu_tx_t *tx;
2561
2562 DB_GET_OBJSET(&os, db);
2563 ds = os->os_dsl_dataset;
2564 tx = os->os_synctx;
2565
2566 (void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE);
2567 dsl_dataset_block_born(ds, bp, tx);
2568 }
2569
2570 mutex_enter(&db->db_mtx);
2571
2572 DBUF_VERIFY(db);
2573
2574 drp = &db->db_last_dirty;
2575 while ((dr = *drp) != db->db_data_pending)
2576 drp = &dr->dr_next;
2577 ASSERT(!list_link_active(&dr->dr_dirty_node));
2578 ASSERT(dr->dr_txg == txg);
2579 ASSERT(dr->dr_dbuf == db);
2580 ASSERT(dr->dr_next == NULL);
2581 *drp = dr->dr_next;
2582
2583 #ifdef ZFS_DEBUG
2584 if (db->db_blkid == DMU_SPILL_BLKID) {
2585 dnode_t *dn;
2586
2587 DB_DNODE_ENTER(db);
2588 dn = DB_DNODE(db);
2589 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
2590 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
2591 db->db_blkptr == &dn->dn_phys->dn_spill);
2592 DB_DNODE_EXIT(db);
2593 }
2594 #endif
2595
2596 if (db->db_level == 0) {
2597 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
2598 ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
2599 if (db->db_state != DB_NOFILL) {
2600 if (dr->dt.dl.dr_data != db->db_buf)
2601 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data,
2602 db) == 1);
2603 else if (!arc_released(db->db_buf))
2604 arc_set_callback(db->db_buf, dbuf_do_evict, db);
2605 }
2606 } else {
2607 dnode_t *dn;
2608
2609 DB_DNODE_ENTER(db);
2610 dn = DB_DNODE(db);
2611 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
2612 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2613 if (!BP_IS_HOLE(db->db_blkptr)) {
2614 int epbs =
2615 dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2616 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==,
2617 db->db.db_size);
2618 ASSERT3U(dn->dn_phys->dn_maxblkid
2619 >> (db->db_level * epbs), >=, db->db_blkid);
2620 arc_set_callback(db->db_buf, dbuf_do_evict, db);
2621 }
2622 DB_DNODE_EXIT(db);
2623 mutex_destroy(&dr->dt.di.dr_mtx);
2624 list_destroy(&dr->dt.di.dr_children);
2625 }
2626 kmem_free(dr, sizeof (dbuf_dirty_record_t));
2627
2628 cv_broadcast(&db->db_changed);
2629 ASSERT(db->db_dirtycnt > 0);
2630 db->db_dirtycnt -= 1;
2631 db->db_data_pending = NULL;
2632 dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg);
2633 }
2634
2635 static void
2636 dbuf_write_nofill_ready(zio_t *zio)
2637 {
2638 dbuf_write_ready(zio, NULL, zio->io_private);
2639 }
2640
2641 static void
2642 dbuf_write_nofill_done(zio_t *zio)
2643 {
2644 dbuf_write_done(zio, NULL, zio->io_private);
2645 }
2646
2647 static void
2648 dbuf_write_override_ready(zio_t *zio)
2649 {
2650 dbuf_dirty_record_t *dr = zio->io_private;
2651 dmu_buf_impl_t *db = dr->dr_dbuf;
2652
2653 dbuf_write_ready(zio, NULL, db);
2654 }
2655
2656 static void
2657 dbuf_write_override_done(zio_t *zio)
2658 {
2659 dbuf_dirty_record_t *dr = zio->io_private;
2660 dmu_buf_impl_t *db = dr->dr_dbuf;
2661 blkptr_t *obp = &dr->dt.dl.dr_overridden_by;
2662
2663 mutex_enter(&db->db_mtx);
2664 if (!BP_EQUAL(zio->io_bp, obp)) {
2665 if (!BP_IS_HOLE(obp))
2666 dsl_free(spa_get_dsl(zio->io_spa), zio->io_txg, obp);
2667 arc_release(dr->dt.dl.dr_data, db);
2668 }
2669 mutex_exit(&db->db_mtx);
2670
2671 dbuf_write_done(zio, NULL, db);
2672 }
2673
2674 static void
2675 dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx)
2676 {
2677 dmu_buf_impl_t *db = dr->dr_dbuf;
2678 dnode_t *dn;
2679 objset_t *os;
2680 dmu_buf_impl_t *parent = db->db_parent;
2681 uint64_t txg = tx->tx_txg;
2682 zbookmark_t zb;
2683 zio_prop_t zp;
2684 zio_t *zio;
2685 int wp_flag = 0;
2686
2687 DB_DNODE_ENTER(db);
2688 dn = DB_DNODE(db);
2689 os = dn->dn_objset;
2690
2691 if (db->db_state != DB_NOFILL) {
2692 if (db->db_level > 0 || dn->dn_type == DMU_OT_DNODE) {
2693 /*
2694 * Private object buffers are released here rather
2695 * than in dbuf_dirty() since they are only modified
2696 * in the syncing context and we don't want the
2697 * overhead of making multiple copies of the data.
2698 */
2699 if (BP_IS_HOLE(db->db_blkptr)) {
2700 arc_buf_thaw(data);
2701 } else {
2702 dbuf_release_bp(db);
2703 }
2704 }
2705 }
2706
2707 if (parent != dn->dn_dbuf) {
2708 ASSERT(parent && parent->db_data_pending);
2709 ASSERT(db->db_level == parent->db_level-1);
2710 ASSERT(arc_released(parent->db_buf));
2711 zio = parent->db_data_pending->dr_zio;
2712 } else {
2713 ASSERT((db->db_level == dn->dn_phys->dn_nlevels-1 &&
2714 db->db_blkid != DMU_SPILL_BLKID) ||
2715 (db->db_blkid == DMU_SPILL_BLKID && db->db_level == 0));
2716 if (db->db_blkid != DMU_SPILL_BLKID)
2717 ASSERT3P(db->db_blkptr, ==,
2718 &dn->dn_phys->dn_blkptr[db->db_blkid]);
2719 zio = dn->dn_zio;
2720 }
2721
2722 ASSERT(db->db_level == 0 || data == db->db_buf);
2723 ASSERT3U(db->db_blkptr->blk_birth, <=, txg);
2724 ASSERT(zio);
2725
2726 SET_BOOKMARK(&zb, os->os_dsl_dataset ?
2727 os->os_dsl_dataset->ds_object : DMU_META_OBJSET,
2728 db->db.db_object, db->db_level, db->db_blkid);
2729
2730 if (db->db_blkid == DMU_SPILL_BLKID)
2731 wp_flag = WP_SPILL;
2732 wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0;
2733
2734 dmu_write_policy(os, dn, db->db_level, wp_flag, &zp);
2735 DB_DNODE_EXIT(db);
2736
2737 if (db->db_level == 0 && dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
2738 ASSERT(db->db_state != DB_NOFILL);
2739 dr->dr_zio = zio_write(zio, os->os_spa, txg,
2740 db->db_blkptr, data->b_data, arc_buf_size(data), &zp,
2741 dbuf_write_override_ready, dbuf_write_override_done, dr,
2742 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
2743 mutex_enter(&db->db_mtx);
2744 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
2745 zio_write_override(dr->dr_zio, &dr->dt.dl.dr_overridden_by,
2746 dr->dt.dl.dr_copies, dr->dt.dl.dr_nopwrite);
2747 mutex_exit(&db->db_mtx);
2748 } else if (db->db_state == DB_NOFILL) {
2749 ASSERT(zp.zp_checksum == ZIO_CHECKSUM_OFF);
2750 dr->dr_zio = zio_write(zio, os->os_spa, txg,
2751 db->db_blkptr, NULL, db->db.db_size, &zp,
2752 dbuf_write_nofill_ready, dbuf_write_nofill_done, db,
2753 ZIO_PRIORITY_ASYNC_WRITE,
2754 ZIO_FLAG_MUSTSUCCEED | ZIO_FLAG_NODATA, &zb);
2755 } else {
2756 ASSERT(arc_released(data));
2757 dr->dr_zio = arc_write(zio, os->os_spa, txg,
2758 db->db_blkptr, data, DBUF_IS_L2CACHEABLE(db), &zp,
2759 dbuf_write_ready, dbuf_write_done, db,
2760 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
2761 }
2762 }