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