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