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