1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
24 * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
25 * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
26 * Copyright (c) 2013, Joyent, Inc. All rights reserved.
27 * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
28 * Copyright (c) 2014 Integros [integros.com]
29 */
30
31 #include <sys/zfs_context.h>
32 #include <sys/dmu.h>
33 #include <sys/dmu_send.h>
34 #include <sys/dmu_impl.h>
35 #include <sys/dbuf.h>
36 #include <sys/dmu_objset.h>
37 #include <sys/dsl_dataset.h>
38 #include <sys/dsl_dir.h>
39 #include <sys/dmu_tx.h>
40 #include <sys/spa.h>
41 #include <sys/zio.h>
42 #include <sys/dmu_zfetch.h>
43 #include <sys/sa.h>
44 #include <sys/sa_impl.h>
45 #include <sys/zfeature.h>
46 #include <sys/blkptr.h>
47 #include <sys/range_tree.h>
48
49 /*
50 * Number of times that zfs_free_range() took the slow path while doing
51 * a zfs receive. A nonzero value indicates a potential performance problem.
52 */
53 uint64_t zfs_free_range_recv_miss;
54
55 static void dbuf_destroy(dmu_buf_impl_t *db);
56 static boolean_t dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
57 static void dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx);
58
59 #ifndef __lint
60 extern inline void dmu_buf_init_user(dmu_buf_user_t *dbu,
61 dmu_buf_evict_func_t *evict_func, dmu_buf_t **clear_on_evict_dbufp);
62 #endif /* ! __lint */
63
64 /*
65 * Global data structures and functions for the dbuf cache.
66 */
67 static kmem_cache_t *dbuf_cache;
68 static taskq_t *dbu_evict_taskq;
69
70 /* ARGSUSED */
71 static int
72 dbuf_cons(void *vdb, void *unused, int kmflag)
73 {
74 dmu_buf_impl_t *db = vdb;
75 bzero(db, sizeof (dmu_buf_impl_t));
76
77 mutex_init(&db->db_mtx, NULL, MUTEX_DEFAULT, NULL);
78 cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL);
79 refcount_create(&db->db_holds);
80
81 return (0);
82 }
83
84 /* ARGSUSED */
85 static void
86 dbuf_dest(void *vdb, void *unused)
87 {
88 dmu_buf_impl_t *db = vdb;
89 mutex_destroy(&db->db_mtx);
90 cv_destroy(&db->db_changed);
91 refcount_destroy(&db->db_holds);
92 }
93
94 /*
95 * dbuf hash table routines
96 */
97 static dbuf_hash_table_t dbuf_hash_table;
98
99 static uint64_t dbuf_hash_count;
100
101 static uint64_t
102 dbuf_hash(void *os, uint64_t obj, uint8_t lvl, uint64_t blkid)
103 {
104 uintptr_t osv = (uintptr_t)os;
105 uint64_t crc = -1ULL;
106
107 ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY);
108 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (lvl)) & 0xFF];
109 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (osv >> 6)) & 0xFF];
110 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 0)) & 0xFF];
111 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 8)) & 0xFF];
112 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 0)) & 0xFF];
113 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 8)) & 0xFF];
114
115 crc ^= (osv>>14) ^ (obj>>16) ^ (blkid>>16);
116
117 return (crc);
118 }
119
120 #define DBUF_HASH(os, obj, level, blkid) dbuf_hash(os, obj, level, blkid);
121
122 #define DBUF_EQUAL(dbuf, os, obj, level, blkid) \
123 ((dbuf)->db.db_object == (obj) && \
124 (dbuf)->db_objset == (os) && \
125 (dbuf)->db_level == (level) && \
126 (dbuf)->db_blkid == (blkid))
127
128 dmu_buf_impl_t *
129 dbuf_find(objset_t *os, uint64_t obj, uint8_t level, uint64_t blkid)
130 {
131 dbuf_hash_table_t *h = &dbuf_hash_table;
132 uint64_t hv = DBUF_HASH(os, obj, level, blkid);
133 uint64_t idx = hv & h->hash_table_mask;
134 dmu_buf_impl_t *db;
135
136 mutex_enter(DBUF_HASH_MUTEX(h, idx));
137 for (db = h->hash_table[idx]; db != NULL; db = db->db_hash_next) {
138 if (DBUF_EQUAL(db, os, obj, level, blkid)) {
139 mutex_enter(&db->db_mtx);
140 if (db->db_state != DB_EVICTING) {
141 mutex_exit(DBUF_HASH_MUTEX(h, idx));
142 return (db);
143 }
144 mutex_exit(&db->db_mtx);
145 }
146 }
147 mutex_exit(DBUF_HASH_MUTEX(h, idx));
148 return (NULL);
149 }
150
151 static dmu_buf_impl_t *
152 dbuf_find_bonus(objset_t *os, uint64_t object)
153 {
154 dnode_t *dn;
155 dmu_buf_impl_t *db = NULL;
156
157 if (dnode_hold(os, object, FTAG, &dn) == 0) {
158 rw_enter(&dn->dn_struct_rwlock, RW_READER);
159 if (dn->dn_bonus != NULL) {
160 db = dn->dn_bonus;
161 mutex_enter(&db->db_mtx);
162 }
163 rw_exit(&dn->dn_struct_rwlock);
164 dnode_rele(dn, FTAG);
165 }
166 return (db);
167 }
168
169 /*
170 * Insert an entry into the hash table. If there is already an element
171 * equal to elem in the hash table, then the already existing element
172 * will be returned and the new element will not be inserted.
173 * Otherwise returns NULL.
174 */
175 static dmu_buf_impl_t *
176 dbuf_hash_insert(dmu_buf_impl_t *db)
177 {
178 dbuf_hash_table_t *h = &dbuf_hash_table;
179 objset_t *os = db->db_objset;
180 uint64_t obj = db->db.db_object;
181 int level = db->db_level;
182 uint64_t blkid = db->db_blkid;
183 uint64_t hv = DBUF_HASH(os, obj, level, blkid);
184 uint64_t idx = hv & h->hash_table_mask;
185 dmu_buf_impl_t *dbf;
186
187 mutex_enter(DBUF_HASH_MUTEX(h, idx));
188 for (dbf = h->hash_table[idx]; dbf != NULL; dbf = dbf->db_hash_next) {
189 if (DBUF_EQUAL(dbf, os, obj, level, blkid)) {
190 mutex_enter(&dbf->db_mtx);
191 if (dbf->db_state != DB_EVICTING) {
192 mutex_exit(DBUF_HASH_MUTEX(h, idx));
193 return (dbf);
194 }
195 mutex_exit(&dbf->db_mtx);
196 }
197 }
198
199 mutex_enter(&db->db_mtx);
200 db->db_hash_next = h->hash_table[idx];
201 h->hash_table[idx] = db;
202 mutex_exit(DBUF_HASH_MUTEX(h, idx));
203 atomic_inc_64(&dbuf_hash_count);
204
205 return (NULL);
206 }
207
208 /*
209 * Remove an entry from the hash table. It must be in the EVICTING state.
210 */
211 static void
212 dbuf_hash_remove(dmu_buf_impl_t *db)
213 {
214 dbuf_hash_table_t *h = &dbuf_hash_table;
215 uint64_t hv = DBUF_HASH(db->db_objset, db->db.db_object,
216 db->db_level, db->db_blkid);
217 uint64_t idx = hv & h->hash_table_mask;
218 dmu_buf_impl_t *dbf, **dbp;
219
220 /*
221 * We musn't hold db_mtx to maintain lock ordering:
222 * DBUF_HASH_MUTEX > db_mtx.
223 */
224 ASSERT(refcount_is_zero(&db->db_holds));
225 ASSERT(db->db_state == DB_EVICTING);
226 ASSERT(!MUTEX_HELD(&db->db_mtx));
227
228 mutex_enter(DBUF_HASH_MUTEX(h, idx));
229 dbp = &h->hash_table[idx];
230 while ((dbf = *dbp) != db) {
231 dbp = &dbf->db_hash_next;
232 ASSERT(dbf != NULL);
233 }
234 *dbp = db->db_hash_next;
235 db->db_hash_next = NULL;
236 mutex_exit(DBUF_HASH_MUTEX(h, idx));
237 atomic_dec_64(&dbuf_hash_count);
238 }
239
240 static arc_evict_func_t dbuf_do_evict;
241
242 typedef enum {
243 DBVU_EVICTING,
244 DBVU_NOT_EVICTING
245 } dbvu_verify_type_t;
246
247 static void
248 dbuf_verify_user(dmu_buf_impl_t *db, dbvu_verify_type_t verify_type)
249 {
250 #ifdef ZFS_DEBUG
251 int64_t holds;
252
253 if (db->db_user == NULL)
254 return;
255
256 /* Only data blocks support the attachment of user data. */
257 ASSERT(db->db_level == 0);
258
259 /* Clients must resolve a dbuf before attaching user data. */
260 ASSERT(db->db.db_data != NULL);
261 ASSERT3U(db->db_state, ==, DB_CACHED);
262
263 holds = refcount_count(&db->db_holds);
264 if (verify_type == DBVU_EVICTING) {
265 /*
266 * Immediate eviction occurs when holds == dirtycnt.
267 * For normal eviction buffers, holds is zero on
268 * eviction, except when dbuf_fix_old_data() calls
269 * dbuf_clear_data(). However, the hold count can grow
270 * during eviction even though db_mtx is held (see
271 * dmu_bonus_hold() for an example), so we can only
272 * test the generic invariant that holds >= dirtycnt.
273 */
274 ASSERT3U(holds, >=, db->db_dirtycnt);
275 } else {
276 if (db->db_user_immediate_evict == TRUE)
277 ASSERT3U(holds, >=, db->db_dirtycnt);
278 else
279 ASSERT3U(holds, >, 0);
280 }
281 #endif
282 }
283
284 static void
285 dbuf_evict_user(dmu_buf_impl_t *db)
286 {
287 dmu_buf_user_t *dbu = db->db_user;
288
289 ASSERT(MUTEX_HELD(&db->db_mtx));
290
291 if (dbu == NULL)
292 return;
293
294 dbuf_verify_user(db, DBVU_EVICTING);
295 db->db_user = NULL;
296
297 #ifdef ZFS_DEBUG
298 if (dbu->dbu_clear_on_evict_dbufp != NULL)
299 *dbu->dbu_clear_on_evict_dbufp = NULL;
300 #endif
301
302 /*
303 * Invoke the callback from a taskq to avoid lock order reversals
304 * and limit stack depth.
305 */
306 taskq_dispatch_ent(dbu_evict_taskq, dbu->dbu_evict_func, dbu, 0,
307 &dbu->dbu_tqent);
308 }
309
310 boolean_t
311 dbuf_is_metadata(dmu_buf_impl_t *db)
312 {
313 if (db->db_level > 0) {
314 return (B_TRUE);
315 } else {
316 boolean_t is_metadata;
317
318 DB_DNODE_ENTER(db);
319 is_metadata = DMU_OT_IS_METADATA(DB_DNODE(db)->dn_type);
320 DB_DNODE_EXIT(db);
321
322 return (is_metadata);
323 }
324 }
325
326 void
327 dbuf_evict(dmu_buf_impl_t *db)
328 {
329 ASSERT(MUTEX_HELD(&db->db_mtx));
330 ASSERT(db->db_buf == NULL);
331 ASSERT(db->db_data_pending == NULL);
332
333 dbuf_clear(db);
334 dbuf_destroy(db);
335 }
336
337 void
338 dbuf_init(void)
339 {
340 uint64_t hsize = 1ULL << 16;
341 dbuf_hash_table_t *h = &dbuf_hash_table;
342 int i;
343
344 /*
345 * The hash table is big enough to fill all of physical memory
346 * with an average 4K block size. The table will take up
347 * totalmem*sizeof(void*)/4K (i.e. 2MB/GB with 8-byte pointers).
348 */
349 while (hsize * 4096 < physmem * PAGESIZE)
350 hsize <<= 1;
351
352 retry:
353 h->hash_table_mask = hsize - 1;
354 h->hash_table = kmem_zalloc(hsize * sizeof (void *), KM_NOSLEEP);
355 if (h->hash_table == NULL) {
356 /* XXX - we should really return an error instead of assert */
357 ASSERT(hsize > (1ULL << 10));
358 hsize >>= 1;
359 goto retry;
360 }
361
362 dbuf_cache = kmem_cache_create("dmu_buf_impl_t",
363 sizeof (dmu_buf_impl_t),
364 0, dbuf_cons, dbuf_dest, NULL, NULL, NULL, 0);
365
366 for (i = 0; i < DBUF_MUTEXES; i++)
367 mutex_init(&h->hash_mutexes[i], NULL, MUTEX_DEFAULT, NULL);
368
369 /*
370 * All entries are queued via taskq_dispatch_ent(), so min/maxalloc
371 * configuration is not required.
372 */
373 dbu_evict_taskq = taskq_create("dbu_evict", 1, minclsyspri, 0, 0, 0);
374 }
375
376 void
377 dbuf_fini(void)
378 {
379 dbuf_hash_table_t *h = &dbuf_hash_table;
380 int i;
381
382 for (i = 0; i < DBUF_MUTEXES; i++)
383 mutex_destroy(&h->hash_mutexes[i]);
384 kmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *));
385 kmem_cache_destroy(dbuf_cache);
386 taskq_destroy(dbu_evict_taskq);
387 }
388
389 /*
390 * Other stuff.
391 */
392
393 #ifdef ZFS_DEBUG
394 static void
395 dbuf_verify(dmu_buf_impl_t *db)
396 {
397 dnode_t *dn;
398 dbuf_dirty_record_t *dr;
399
400 ASSERT(MUTEX_HELD(&db->db_mtx));
401
402 if (!(zfs_flags & ZFS_DEBUG_DBUF_VERIFY))
403 return;
404
405 ASSERT(db->db_objset != NULL);
406 DB_DNODE_ENTER(db);
407 dn = DB_DNODE(db);
408 if (dn == NULL) {
409 ASSERT(db->db_parent == NULL);
410 ASSERT(db->db_blkptr == NULL);
411 } else {
412 ASSERT3U(db->db.db_object, ==, dn->dn_object);
413 ASSERT3P(db->db_objset, ==, dn->dn_objset);
414 ASSERT3U(db->db_level, <, dn->dn_nlevels);
415 ASSERT(db->db_blkid == DMU_BONUS_BLKID ||
416 db->db_blkid == DMU_SPILL_BLKID ||
417 !avl_is_empty(&dn->dn_dbufs));
418 }
419 if (db->db_blkid == DMU_BONUS_BLKID) {
420 ASSERT(dn != NULL);
421 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
422 ASSERT3U(db->db.db_offset, ==, DMU_BONUS_BLKID);
423 } else if (db->db_blkid == DMU_SPILL_BLKID) {
424 ASSERT(dn != NULL);
425 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
426 ASSERT0(db->db.db_offset);
427 } else {
428 ASSERT3U(db->db.db_offset, ==, db->db_blkid * db->db.db_size);
429 }
430
431 for (dr = db->db_data_pending; dr != NULL; dr = dr->dr_next)
432 ASSERT(dr->dr_dbuf == db);
433
434 for (dr = db->db_last_dirty; dr != NULL; dr = dr->dr_next)
435 ASSERT(dr->dr_dbuf == db);
436
437 /*
438 * We can't assert that db_size matches dn_datablksz because it
439 * can be momentarily different when another thread is doing
440 * dnode_set_blksz().
441 */
442 if (db->db_level == 0 && db->db.db_object == DMU_META_DNODE_OBJECT) {
443 dr = db->db_data_pending;
444 /*
445 * It should only be modified in syncing context, so
446 * make sure we only have one copy of the data.
447 */
448 ASSERT(dr == NULL || dr->dt.dl.dr_data == db->db_buf);
449 }
450
451 /* verify db->db_blkptr */
452 if (db->db_blkptr) {
453 if (db->db_parent == dn->dn_dbuf) {
454 /* db is pointed to by the dnode */
455 /* ASSERT3U(db->db_blkid, <, dn->dn_nblkptr); */
456 if (DMU_OBJECT_IS_SPECIAL(db->db.db_object))
457 ASSERT(db->db_parent == NULL);
458 else
459 ASSERT(db->db_parent != NULL);
460 if (db->db_blkid != DMU_SPILL_BLKID)
461 ASSERT3P(db->db_blkptr, ==,
462 &dn->dn_phys->dn_blkptr[db->db_blkid]);
463 } else {
464 /* db is pointed to by an indirect block */
465 int epb = db->db_parent->db.db_size >> SPA_BLKPTRSHIFT;
466 ASSERT3U(db->db_parent->db_level, ==, db->db_level+1);
467 ASSERT3U(db->db_parent->db.db_object, ==,
468 db->db.db_object);
469 /*
470 * dnode_grow_indblksz() can make this fail if we don't
471 * have the struct_rwlock. XXX indblksz no longer
472 * grows. safe to do this now?
473 */
474 if (RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
475 ASSERT3P(db->db_blkptr, ==,
476 ((blkptr_t *)db->db_parent->db.db_data +
477 db->db_blkid % epb));
478 }
479 }
480 }
481 if ((db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr)) &&
482 (db->db_buf == NULL || db->db_buf->b_data) &&
483 db->db.db_data && db->db_blkid != DMU_BONUS_BLKID &&
484 db->db_state != DB_FILL && !dn->dn_free_txg) {
485 /*
486 * If the blkptr isn't set but they have nonzero data,
487 * it had better be dirty, otherwise we'll lose that
488 * data when we evict this buffer.
489 */
490 if (db->db_dirtycnt == 0) {
491 uint64_t *buf = db->db.db_data;
492 int i;
493
494 for (i = 0; i < db->db.db_size >> 3; i++) {
495 ASSERT(buf[i] == 0);
496 }
497 }
498 }
499 DB_DNODE_EXIT(db);
500 }
501 #endif
502
503 static void
504 dbuf_clear_data(dmu_buf_impl_t *db)
505 {
506 ASSERT(MUTEX_HELD(&db->db_mtx));
507 dbuf_evict_user(db);
508 db->db_buf = NULL;
509 db->db.db_data = NULL;
510 if (db->db_state != DB_NOFILL)
511 db->db_state = DB_UNCACHED;
512 }
513
514 static void
515 dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf)
516 {
517 ASSERT(MUTEX_HELD(&db->db_mtx));
518 ASSERT(buf != NULL);
519
520 db->db_buf = buf;
521 ASSERT(buf->b_data != NULL);
522 db->db.db_data = buf->b_data;
523 if (!arc_released(buf))
524 arc_set_callback(buf, dbuf_do_evict, db);
525 }
526
527 /*
528 * Loan out an arc_buf for read. Return the loaned arc_buf.
529 */
530 arc_buf_t *
531 dbuf_loan_arcbuf(dmu_buf_impl_t *db)
532 {
533 arc_buf_t *abuf;
534
535 mutex_enter(&db->db_mtx);
536 if (arc_released(db->db_buf) || refcount_count(&db->db_holds) > 1) {
537 int blksz = db->db.db_size;
538 spa_t *spa = db->db_objset->os_spa;
539
540 mutex_exit(&db->db_mtx);
541 abuf = arc_loan_buf(spa, blksz);
542 bcopy(db->db.db_data, abuf->b_data, blksz);
543 } else {
544 abuf = db->db_buf;
545 arc_loan_inuse_buf(abuf, db);
546 dbuf_clear_data(db);
547 mutex_exit(&db->db_mtx);
548 }
549 return (abuf);
550 }
551
552 /*
553 * Calculate which level n block references the data at the level 0 offset
554 * provided.
555 */
556 uint64_t
557 dbuf_whichblock(dnode_t *dn, int64_t level, uint64_t offset)
558 {
559 if (dn->dn_datablkshift != 0 && dn->dn_indblkshift != 0) {
560 /*
561 * The level n blkid is equal to the level 0 blkid divided by
562 * the number of level 0s in a level n block.
563 *
564 * The level 0 blkid is offset >> datablkshift =
565 * offset / 2^datablkshift.
566 *
567 * The number of level 0s in a level n is the number of block
568 * pointers in an indirect block, raised to the power of level.
569 * This is 2^(indblkshift - SPA_BLKPTRSHIFT)^level =
570 * 2^(level*(indblkshift - SPA_BLKPTRSHIFT)).
571 *
572 * Thus, the level n blkid is: offset /
573 * ((2^datablkshift)*(2^(level*(indblkshift - SPA_BLKPTRSHIFT)))
574 * = offset / 2^(datablkshift + level *
575 * (indblkshift - SPA_BLKPTRSHIFT))
576 * = offset >> (datablkshift + level *
577 * (indblkshift - SPA_BLKPTRSHIFT))
578 */
579 return (offset >> (dn->dn_datablkshift + level *
580 (dn->dn_indblkshift - SPA_BLKPTRSHIFT)));
581 } else {
582 ASSERT3U(offset, <, dn->dn_datablksz);
583 return (0);
584 }
585 }
586
587 static void
588 dbuf_read_done(zio_t *zio, arc_buf_t *buf, void *vdb)
589 {
590 dmu_buf_impl_t *db = vdb;
591
592 mutex_enter(&db->db_mtx);
593 ASSERT3U(db->db_state, ==, DB_READ);
594 /*
595 * All reads are synchronous, so we must have a hold on the dbuf
596 */
597 ASSERT(refcount_count(&db->db_holds) > 0);
598 ASSERT(db->db_buf == NULL);
599 ASSERT(db->db.db_data == NULL);
600 if (db->db_level == 0 && db->db_freed_in_flight) {
601 /* we were freed in flight; disregard any error */
602 arc_release(buf, db);
603 bzero(buf->b_data, db->db.db_size);
604 arc_buf_freeze(buf);
605 db->db_freed_in_flight = FALSE;
606 dbuf_set_data(db, buf);
607 db->db_state = DB_CACHED;
608 } else if (zio == NULL || zio->io_error == 0) {
609 dbuf_set_data(db, buf);
610 db->db_state = DB_CACHED;
611 } else {
612 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
613 ASSERT3P(db->db_buf, ==, NULL);
614 VERIFY(arc_buf_remove_ref(buf, db));
615 db->db_state = DB_UNCACHED;
616 }
617 cv_broadcast(&db->db_changed);
618 dbuf_rele_and_unlock(db, NULL);
619 }
620
621 static void
622 dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
623 {
624 dnode_t *dn;
625 zbookmark_phys_t zb;
626 arc_flags_t aflags = ARC_FLAG_NOWAIT;
627
628 DB_DNODE_ENTER(db);
629 dn = DB_DNODE(db);
630 ASSERT(!refcount_is_zero(&db->db_holds));
631 /* We need the struct_rwlock to prevent db_blkptr from changing. */
632 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
633 ASSERT(MUTEX_HELD(&db->db_mtx));
634 ASSERT(db->db_state == DB_UNCACHED);
635 ASSERT(db->db_buf == NULL);
636
637 if (db->db_blkid == DMU_BONUS_BLKID) {
638 int bonuslen = MIN(dn->dn_bonuslen, dn->dn_phys->dn_bonuslen);
639
640 ASSERT3U(bonuslen, <=, db->db.db_size);
641 db->db.db_data = zio_buf_alloc(DN_MAX_BONUSLEN);
642 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
643 if (bonuslen < DN_MAX_BONUSLEN)
644 bzero(db->db.db_data, DN_MAX_BONUSLEN);
645 if (bonuslen)
646 bcopy(DN_BONUS(dn->dn_phys), db->db.db_data, bonuslen);
647 DB_DNODE_EXIT(db);
648 db->db_state = DB_CACHED;
649 mutex_exit(&db->db_mtx);
650 return;
651 }
652
653 /*
654 * Recheck BP_IS_HOLE() after dnode_block_freed() in case dnode_sync()
655 * processes the delete record and clears the bp while we are waiting
656 * for the dn_mtx (resulting in a "no" from block_freed).
657 */
658 if (db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr) ||
659 (db->db_level == 0 && (dnode_block_freed(dn, db->db_blkid) ||
660 BP_IS_HOLE(db->db_blkptr)))) {
661 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
662
663 DB_DNODE_EXIT(db);
664 dbuf_set_data(db, arc_buf_alloc(db->db_objset->os_spa,
665 db->db.db_size, db, type));
666 bzero(db->db.db_data, db->db.db_size);
667 db->db_state = DB_CACHED;
668 mutex_exit(&db->db_mtx);
669 return;
670 }
671
672 DB_DNODE_EXIT(db);
673
674 db->db_state = DB_READ;
675 mutex_exit(&db->db_mtx);
676
677 if (DBUF_IS_L2CACHEABLE(db))
678 aflags |= ARC_FLAG_L2CACHE;
679 if (DBUF_IS_L2COMPRESSIBLE(db))
680 aflags |= ARC_FLAG_L2COMPRESS;
681
682 SET_BOOKMARK(&zb, db->db_objset->os_dsl_dataset ?
683 db->db_objset->os_dsl_dataset->ds_object : DMU_META_OBJSET,
684 db->db.db_object, db->db_level, db->db_blkid);
685
686 dbuf_add_ref(db, NULL);
687
688 (void) arc_read(zio, db->db_objset->os_spa, db->db_blkptr,
689 dbuf_read_done, db, ZIO_PRIORITY_SYNC_READ,
690 (flags & DB_RF_CANFAIL) ? ZIO_FLAG_CANFAIL : ZIO_FLAG_MUSTSUCCEED,
691 &aflags, &zb);
692 }
693
694 int
695 dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
696 {
697 int err = 0;
698 boolean_t havepzio = (zio != NULL);
699 boolean_t prefetch;
700 dnode_t *dn;
701
702 /*
703 * We don't have to hold the mutex to check db_state because it
704 * can't be freed while we have a hold on the buffer.
705 */
706 ASSERT(!refcount_is_zero(&db->db_holds));
707
708 if (db->db_state == DB_NOFILL)
709 return (SET_ERROR(EIO));
710
711 DB_DNODE_ENTER(db);
712 dn = DB_DNODE(db);
713 if ((flags & DB_RF_HAVESTRUCT) == 0)
714 rw_enter(&dn->dn_struct_rwlock, RW_READER);
715
716 prefetch = db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
717 (flags & DB_RF_NOPREFETCH) == 0 && dn != NULL &&
718 DBUF_IS_CACHEABLE(db);
719
720 mutex_enter(&db->db_mtx);
721 if (db->db_state == DB_CACHED) {
722 mutex_exit(&db->db_mtx);
723 if (prefetch)
724 dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1);
725 if ((flags & DB_RF_HAVESTRUCT) == 0)
726 rw_exit(&dn->dn_struct_rwlock);
727 DB_DNODE_EXIT(db);
728 } else if (db->db_state == DB_UNCACHED) {
729 spa_t *spa = dn->dn_objset->os_spa;
730
731 if (zio == NULL)
732 zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL);
733 dbuf_read_impl(db, zio, flags);
734
735 /* dbuf_read_impl has dropped db_mtx for us */
736
737 if (prefetch)
738 dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1);
739
740 if ((flags & DB_RF_HAVESTRUCT) == 0)
741 rw_exit(&dn->dn_struct_rwlock);
742 DB_DNODE_EXIT(db);
743
744 if (!havepzio)
745 err = zio_wait(zio);
746 } else {
747 /*
748 * Another reader came in while the dbuf was in flight
749 * between UNCACHED and CACHED. Either a writer will finish
750 * writing the buffer (sending the dbuf to CACHED) or the
751 * first reader's request will reach the read_done callback
752 * and send the dbuf to CACHED. Otherwise, a failure
753 * occurred and the dbuf went to UNCACHED.
754 */
755 mutex_exit(&db->db_mtx);
756 if (prefetch)
757 dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1);
758 if ((flags & DB_RF_HAVESTRUCT) == 0)
759 rw_exit(&dn->dn_struct_rwlock);
760 DB_DNODE_EXIT(db);
761
762 /* Skip the wait per the caller's request. */
763 mutex_enter(&db->db_mtx);
764 if ((flags & DB_RF_NEVERWAIT) == 0) {
765 while (db->db_state == DB_READ ||
766 db->db_state == DB_FILL) {
767 ASSERT(db->db_state == DB_READ ||
768 (flags & DB_RF_HAVESTRUCT) == 0);
769 DTRACE_PROBE2(blocked__read, dmu_buf_impl_t *,
770 db, zio_t *, zio);
771 cv_wait(&db->db_changed, &db->db_mtx);
772 }
773 if (db->db_state == DB_UNCACHED)
774 err = SET_ERROR(EIO);
775 }
776 mutex_exit(&db->db_mtx);
777 }
778
779 ASSERT(err || havepzio || db->db_state == DB_CACHED);
780 return (err);
781 }
782
783 static void
784 dbuf_noread(dmu_buf_impl_t *db)
785 {
786 ASSERT(!refcount_is_zero(&db->db_holds));
787 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
788 mutex_enter(&db->db_mtx);
789 while (db->db_state == DB_READ || db->db_state == DB_FILL)
790 cv_wait(&db->db_changed, &db->db_mtx);
791 if (db->db_state == DB_UNCACHED) {
792 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
793 spa_t *spa = db->db_objset->os_spa;
794
795 ASSERT(db->db_buf == NULL);
796 ASSERT(db->db.db_data == NULL);
797 dbuf_set_data(db, arc_buf_alloc(spa, db->db.db_size, db, type));
798 db->db_state = DB_FILL;
799 } else if (db->db_state == DB_NOFILL) {
800 dbuf_clear_data(db);
801 } else {
802 ASSERT3U(db->db_state, ==, DB_CACHED);
803 }
804 mutex_exit(&db->db_mtx);
805 }
806
807 /*
808 * This is our just-in-time copy function. It makes a copy of
809 * buffers, that have been modified in a previous transaction
810 * group, before we modify them in the current active group.
811 *
812 * This function is used in two places: when we are dirtying a
813 * buffer for the first time in a txg, and when we are freeing
814 * a range in a dnode that includes this buffer.
815 *
816 * Note that when we are called from dbuf_free_range() we do
817 * not put a hold on the buffer, we just traverse the active
818 * dbuf list for the dnode.
819 */
820 static void
821 dbuf_fix_old_data(dmu_buf_impl_t *db, uint64_t txg)
822 {
823 dbuf_dirty_record_t *dr = db->db_last_dirty;
824
825 ASSERT(MUTEX_HELD(&db->db_mtx));
826 ASSERT(db->db.db_data != NULL);
827 ASSERT(db->db_level == 0);
828 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT);
829
830 if (dr == NULL ||
831 (dr->dt.dl.dr_data !=
832 ((db->db_blkid == DMU_BONUS_BLKID) ? db->db.db_data : db->db_buf)))
833 return;
834
835 /*
836 * If the last dirty record for this dbuf has not yet synced
837 * and its referencing the dbuf data, either:
838 * reset the reference to point to a new copy,
839 * or (if there a no active holders)
840 * just null out the current db_data pointer.
841 */
842 ASSERT(dr->dr_txg >= txg - 2);
843 if (db->db_blkid == DMU_BONUS_BLKID) {
844 /* Note that the data bufs here are zio_bufs */
845 dr->dt.dl.dr_data = zio_buf_alloc(DN_MAX_BONUSLEN);
846 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
847 bcopy(db->db.db_data, dr->dt.dl.dr_data, DN_MAX_BONUSLEN);
848 } else if (refcount_count(&db->db_holds) > db->db_dirtycnt) {
849 int size = db->db.db_size;
850 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
851 spa_t *spa = db->db_objset->os_spa;
852
853 dr->dt.dl.dr_data = arc_buf_alloc(spa, size, db, type);
854 bcopy(db->db.db_data, dr->dt.dl.dr_data->b_data, size);
855 } else {
856 dbuf_clear_data(db);
857 }
858 }
859
860 void
861 dbuf_unoverride(dbuf_dirty_record_t *dr)
862 {
863 dmu_buf_impl_t *db = dr->dr_dbuf;
864 blkptr_t *bp = &dr->dt.dl.dr_overridden_by;
865 uint64_t txg = dr->dr_txg;
866
867 ASSERT(MUTEX_HELD(&db->db_mtx));
868 ASSERT(dr->dt.dl.dr_override_state != DR_IN_DMU_SYNC);
869 ASSERT(db->db_level == 0);
870
871 if (db->db_blkid == DMU_BONUS_BLKID ||
872 dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN)
873 return;
874
875 ASSERT(db->db_data_pending != dr);
876
877 /* free this block */
878 if (!BP_IS_HOLE(bp) && !dr->dt.dl.dr_nopwrite)
879 zio_free(db->db_objset->os_spa, txg, bp);
880
881 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
882 dr->dt.dl.dr_nopwrite = B_FALSE;
883
884 /*
885 * Release the already-written buffer, so we leave it in
886 * a consistent dirty state. Note that all callers are
887 * modifying the buffer, so they will immediately do
888 * another (redundant) arc_release(). Therefore, leave
889 * the buf thawed to save the effort of freezing &
890 * immediately re-thawing it.
891 */
892 arc_release(dr->dt.dl.dr_data, db);
893 }
894
895 /*
896 * Evict (if its unreferenced) or clear (if its referenced) any level-0
897 * data blocks in the free range, so that any future readers will find
898 * empty blocks.
899 *
900 * This is a no-op if the dataset is in the middle of an incremental
901 * receive; see comment below for details.
902 */
903 void
904 dbuf_free_range(dnode_t *dn, uint64_t start_blkid, uint64_t end_blkid,
905 dmu_tx_t *tx)
906 {
907 dmu_buf_impl_t db_search;
908 dmu_buf_impl_t *db, *db_next;
909 uint64_t txg = tx->tx_txg;
910 avl_index_t where;
911 boolean_t freespill =
912 (start_blkid == DMU_SPILL_BLKID || end_blkid == DMU_SPILL_BLKID);
913
914 if (end_blkid > dn->dn_maxblkid && !freespill)
915 end_blkid = dn->dn_maxblkid;
916 dprintf_dnode(dn, "start=%llu end=%llu\n", start_blkid, end_blkid);
917
918 db_search.db_level = 0;
919 db_search.db_blkid = start_blkid;
920 db_search.db_state = DB_SEARCH;
921
922 mutex_enter(&dn->dn_dbufs_mtx);
923 if (start_blkid >= dn->dn_unlisted_l0_blkid && !freespill) {
924 /* There can't be any dbufs in this range; no need to search. */
925 #ifdef DEBUG
926 db = avl_find(&dn->dn_dbufs, &db_search, &where);
927 ASSERT3P(db, ==, NULL);
928 db = avl_nearest(&dn->dn_dbufs, where, AVL_AFTER);
929 ASSERT(db == NULL || db->db_level > 0);
930 #endif
931 mutex_exit(&dn->dn_dbufs_mtx);
932 return;
933 } else if (dmu_objset_is_receiving(dn->dn_objset)) {
934 /*
935 * If we are receiving, we expect there to be no dbufs in
936 * the range to be freed, because receive modifies each
937 * block at most once, and in offset order. If this is
938 * not the case, it can lead to performance problems,
939 * so note that we unexpectedly took the slow path.
940 */
941 atomic_inc_64(&zfs_free_range_recv_miss);
942 }
943
944 db = avl_find(&dn->dn_dbufs, &db_search, &where);
945 ASSERT3P(db, ==, NULL);
946 db = avl_nearest(&dn->dn_dbufs, where, AVL_AFTER);
947
948 for (; db != NULL; db = db_next) {
949 db_next = AVL_NEXT(&dn->dn_dbufs, db);
950 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
951
952 if (db->db_level != 0 || db->db_blkid > end_blkid) {
953 break;
954 }
955 ASSERT3U(db->db_blkid, >=, start_blkid);
956
957 /* found a level 0 buffer in the range */
958 mutex_enter(&db->db_mtx);
959 if (dbuf_undirty(db, tx)) {
960 /* mutex has been dropped and dbuf destroyed */
961 continue;
962 }
963
964 if (db->db_state == DB_UNCACHED ||
965 db->db_state == DB_NOFILL ||
966 db->db_state == DB_EVICTING) {
967 ASSERT(db->db.db_data == NULL);
968 mutex_exit(&db->db_mtx);
969 continue;
970 }
971 if (db->db_state == DB_READ || db->db_state == DB_FILL) {
972 /* will be handled in dbuf_read_done or dbuf_rele */
973 db->db_freed_in_flight = TRUE;
974 mutex_exit(&db->db_mtx);
975 continue;
976 }
977 if (refcount_count(&db->db_holds) == 0) {
978 ASSERT(db->db_buf);
979 dbuf_clear(db);
980 continue;
981 }
982 /* The dbuf is referenced */
983
984 if (db->db_last_dirty != NULL) {
985 dbuf_dirty_record_t *dr = db->db_last_dirty;
986
987 if (dr->dr_txg == txg) {
988 /*
989 * This buffer is "in-use", re-adjust the file
990 * size to reflect that this buffer may
991 * contain new data when we sync.
992 */
993 if (db->db_blkid != DMU_SPILL_BLKID &&
994 db->db_blkid > dn->dn_maxblkid)
995 dn->dn_maxblkid = db->db_blkid;
996 dbuf_unoverride(dr);
997 } else {
998 /*
999 * This dbuf is not dirty in the open context.
1000 * Either uncache it (if its not referenced in
1001 * the open context) or reset its contents to
1002 * empty.
1003 */
1004 dbuf_fix_old_data(db, txg);
1005 }
1006 }
1007 /* clear the contents if its cached */
1008 if (db->db_state == DB_CACHED) {
1009 ASSERT(db->db.db_data != NULL);
1010 arc_release(db->db_buf, db);
1011 bzero(db->db.db_data, db->db.db_size);
1012 arc_buf_freeze(db->db_buf);
1013 }
1014
1015 mutex_exit(&db->db_mtx);
1016 }
1017 mutex_exit(&dn->dn_dbufs_mtx);
1018 }
1019
1020 static int
1021 dbuf_block_freeable(dmu_buf_impl_t *db)
1022 {
1023 dsl_dataset_t *ds = db->db_objset->os_dsl_dataset;
1024 uint64_t birth_txg = 0;
1025
1026 /*
1027 * We don't need any locking to protect db_blkptr:
1028 * If it's syncing, then db_last_dirty will be set
1029 * so we'll ignore db_blkptr.
1030 *
1031 * This logic ensures that only block births for
1032 * filled blocks are considered.
1033 */
1034 ASSERT(MUTEX_HELD(&db->db_mtx));
1035 if (db->db_last_dirty && (db->db_blkptr == NULL ||
1036 !BP_IS_HOLE(db->db_blkptr))) {
1037 birth_txg = db->db_last_dirty->dr_txg;
1038 } else if (db->db_blkptr != NULL && !BP_IS_HOLE(db->db_blkptr)) {
1039 birth_txg = db->db_blkptr->blk_birth;
1040 }
1041
1042 /*
1043 * If this block don't exist or is in a snapshot, it can't be freed.
1044 * Don't pass the bp to dsl_dataset_block_freeable() since we
1045 * are holding the db_mtx lock and might deadlock if we are
1046 * prefetching a dedup-ed block.
1047 */
1048 if (birth_txg != 0)
1049 return (ds == NULL ||
1050 dsl_dataset_block_freeable(ds, NULL, birth_txg));
1051 else
1052 return (B_FALSE);
1053 }
1054
1055 void
1056 dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx)
1057 {
1058 arc_buf_t *buf, *obuf;
1059 int osize = db->db.db_size;
1060 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
1061 dnode_t *dn;
1062
1063 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1064
1065 DB_DNODE_ENTER(db);
1066 dn = DB_DNODE(db);
1067
1068 /* XXX does *this* func really need the lock? */
1069 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
1070
1071 /*
1072 * This call to dmu_buf_will_dirty() with the dn_struct_rwlock held
1073 * is OK, because there can be no other references to the db
1074 * when we are changing its size, so no concurrent DB_FILL can
1075 * be happening.
1076 */
1077 /*
1078 * XXX we should be doing a dbuf_read, checking the return
1079 * value and returning that up to our callers
1080 */
1081 dmu_buf_will_dirty(&db->db, tx);
1082
1083 /* create the data buffer for the new block */
1084 buf = arc_buf_alloc(dn->dn_objset->os_spa, size, db, type);
1085
1086 /* copy old block data to the new block */
1087 obuf = db->db_buf;
1088 bcopy(obuf->b_data, buf->b_data, MIN(osize, size));
1089 /* zero the remainder */
1090 if (size > osize)
1091 bzero((uint8_t *)buf->b_data + osize, size - osize);
1092
1093 mutex_enter(&db->db_mtx);
1094 dbuf_set_data(db, buf);
1095 VERIFY(arc_buf_remove_ref(obuf, db));
1096 db->db.db_size = size;
1097
1098 if (db->db_level == 0) {
1099 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
1100 db->db_last_dirty->dt.dl.dr_data = buf;
1101 }
1102 mutex_exit(&db->db_mtx);
1103
1104 dnode_willuse_space(dn, size-osize, tx);
1105 DB_DNODE_EXIT(db);
1106 }
1107
1108 void
1109 dbuf_release_bp(dmu_buf_impl_t *db)
1110 {
1111 objset_t *os = db->db_objset;
1112
1113 ASSERT(dsl_pool_sync_context(dmu_objset_pool(os)));
1114 ASSERT(arc_released(os->os_phys_buf) ||
1115 list_link_active(&os->os_dsl_dataset->ds_synced_link));
1116 ASSERT(db->db_parent == NULL || arc_released(db->db_parent->db_buf));
1117
1118 (void) arc_release(db->db_buf, db);
1119 }
1120
1121 /*
1122 * We already have a dirty record for this TXG, and we are being
1123 * dirtied again.
1124 */
1125 static void
1126 dbuf_redirty(dbuf_dirty_record_t *dr)
1127 {
1128 dmu_buf_impl_t *db = dr->dr_dbuf;
1129
1130 ASSERT(MUTEX_HELD(&db->db_mtx));
1131
1132 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID) {
1133 /*
1134 * If this buffer has already been written out,
1135 * we now need to reset its state.
1136 */
1137 dbuf_unoverride(dr);
1138 if (db->db.db_object != DMU_META_DNODE_OBJECT &&
1139 db->db_state != DB_NOFILL) {
1140 /* Already released on initial dirty, so just thaw. */
1141 ASSERT(arc_released(db->db_buf));
1142 arc_buf_thaw(db->db_buf);
1143 }
1144 }
1145 }
1146
1147 dbuf_dirty_record_t *
1148 dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1149 {
1150 dnode_t *dn;
1151 objset_t *os;
1152 dbuf_dirty_record_t **drp, *dr;
1153 int drop_struct_lock = FALSE;
1154 boolean_t do_free_accounting = B_FALSE;
1155 int txgoff = tx->tx_txg & TXG_MASK;
1156
1157 ASSERT(tx->tx_txg != 0);
1158 ASSERT(!refcount_is_zero(&db->db_holds));
1159 DMU_TX_DIRTY_BUF(tx, db);
1160
1161 DB_DNODE_ENTER(db);
1162 dn = DB_DNODE(db);
1163 /*
1164 * Shouldn't dirty a regular buffer in syncing context. Private
1165 * objects may be dirtied in syncing context, but only if they
1166 * were already pre-dirtied in open context.
1167 */
1168 ASSERT(!dmu_tx_is_syncing(tx) ||
1169 BP_IS_HOLE(dn->dn_objset->os_rootbp) ||
1170 DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1171 dn->dn_objset->os_dsl_dataset == NULL);
1172 /*
1173 * We make this assert for private objects as well, but after we
1174 * check if we're already dirty. They are allowed to re-dirty
1175 * in syncing context.
1176 */
1177 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1178 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1179 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1180
1181 mutex_enter(&db->db_mtx);
1182 /*
1183 * XXX make this true for indirects too? The problem is that
1184 * transactions created with dmu_tx_create_assigned() from
1185 * syncing context don't bother holding ahead.
1186 */
1187 ASSERT(db->db_level != 0 ||
1188 db->db_state == DB_CACHED || db->db_state == DB_FILL ||
1189 db->db_state == DB_NOFILL);
1190
1191 mutex_enter(&dn->dn_mtx);
1192 /*
1193 * Don't set dirtyctx to SYNC if we're just modifying this as we
1194 * initialize the objset.
1195 */
1196 if (dn->dn_dirtyctx == DN_UNDIRTIED &&
1197 !BP_IS_HOLE(dn->dn_objset->os_rootbp)) {
1198 dn->dn_dirtyctx =
1199 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN);
1200 ASSERT(dn->dn_dirtyctx_firstset == NULL);
1201 dn->dn_dirtyctx_firstset = kmem_alloc(1, KM_SLEEP);
1202 }
1203 mutex_exit(&dn->dn_mtx);
1204
1205 if (db->db_blkid == DMU_SPILL_BLKID)
1206 dn->dn_have_spill = B_TRUE;
1207
1208 /*
1209 * If this buffer is already dirty, we're done.
1210 */
1211 drp = &db->db_last_dirty;
1212 ASSERT(*drp == NULL || (*drp)->dr_txg <= tx->tx_txg ||
1213 db->db.db_object == DMU_META_DNODE_OBJECT);
1214 while ((dr = *drp) != NULL && dr->dr_txg > tx->tx_txg)
1215 drp = &dr->dr_next;
1216 if (dr && dr->dr_txg == tx->tx_txg) {
1217 DB_DNODE_EXIT(db);
1218
1219 dbuf_redirty(dr);
1220 mutex_exit(&db->db_mtx);
1221 return (dr);
1222 }
1223
1224 /*
1225 * Only valid if not already dirty.
1226 */
1227 ASSERT(dn->dn_object == 0 ||
1228 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1229 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1230
1231 ASSERT3U(dn->dn_nlevels, >, db->db_level);
1232 ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) ||
1233 dn->dn_phys->dn_nlevels > db->db_level ||
1234 dn->dn_next_nlevels[txgoff] > db->db_level ||
1235 dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level ||
1236 dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level);
1237
1238 /*
1239 * We should only be dirtying in syncing context if it's the
1240 * mos or we're initializing the os or it's a special object.
1241 * However, we are allowed to dirty in syncing context provided
1242 * we already dirtied it in open context. Hence we must make
1243 * this assertion only if we're not already dirty.
1244 */
1245 os = dn->dn_objset;
1246 ASSERT(!dmu_tx_is_syncing(tx) || DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1247 os->os_dsl_dataset == NULL || BP_IS_HOLE(os->os_rootbp));
1248 ASSERT(db->db.db_size != 0);
1249
1250 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1251
1252 if (db->db_blkid != DMU_BONUS_BLKID) {
1253 /*
1254 * Update the accounting.
1255 * Note: we delay "free accounting" until after we drop
1256 * the db_mtx. This keeps us from grabbing other locks
1257 * (and possibly deadlocking) in bp_get_dsize() while
1258 * also holding the db_mtx.
1259 */
1260 dnode_willuse_space(dn, db->db.db_size, tx);
1261 do_free_accounting = dbuf_block_freeable(db);
1262 }
1263
1264 /*
1265 * If this buffer is dirty in an old transaction group we need
1266 * to make a copy of it so that the changes we make in this
1267 * transaction group won't leak out when we sync the older txg.
1268 */
1269 dr = kmem_zalloc(sizeof (dbuf_dirty_record_t), KM_SLEEP);
1270 if (db->db_level == 0) {
1271 void *data_old = db->db_buf;
1272
1273 if (db->db_state != DB_NOFILL) {
1274 if (db->db_blkid == DMU_BONUS_BLKID) {
1275 dbuf_fix_old_data(db, tx->tx_txg);
1276 data_old = db->db.db_data;
1277 } else if (db->db.db_object != DMU_META_DNODE_OBJECT) {
1278 /*
1279 * Release the data buffer from the cache so
1280 * that we can modify it without impacting
1281 * possible other users of this cached data
1282 * block. Note that indirect blocks and
1283 * private objects are not released until the
1284 * syncing state (since they are only modified
1285 * then).
1286 */
1287 arc_release(db->db_buf, db);
1288 dbuf_fix_old_data(db, tx->tx_txg);
1289 data_old = db->db_buf;
1290 }
1291 ASSERT(data_old != NULL);
1292 }
1293 dr->dt.dl.dr_data = data_old;
1294 } else {
1295 mutex_init(&dr->dt.di.dr_mtx, NULL, MUTEX_DEFAULT, NULL);
1296 list_create(&dr->dt.di.dr_children,
1297 sizeof (dbuf_dirty_record_t),
1298 offsetof(dbuf_dirty_record_t, dr_dirty_node));
1299 }
1300 if (db->db_blkid != DMU_BONUS_BLKID && os->os_dsl_dataset != NULL)
1301 dr->dr_accounted = db->db.db_size;
1302 dr->dr_dbuf = db;
1303 dr->dr_txg = tx->tx_txg;
1304 dr->dr_next = *drp;
1305 *drp = dr;
1306
1307 /*
1308 * We could have been freed_in_flight between the dbuf_noread
1309 * and dbuf_dirty. We win, as though the dbuf_noread() had
1310 * happened after the free.
1311 */
1312 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
1313 db->db_blkid != DMU_SPILL_BLKID) {
1314 mutex_enter(&dn->dn_mtx);
1315 if (dn->dn_free_ranges[txgoff] != NULL) {
1316 range_tree_clear(dn->dn_free_ranges[txgoff],
1317 db->db_blkid, 1);
1318 }
1319 mutex_exit(&dn->dn_mtx);
1320 db->db_freed_in_flight = FALSE;
1321 }
1322
1323 /*
1324 * This buffer is now part of this txg
1325 */
1326 dbuf_add_ref(db, (void *)(uintptr_t)tx->tx_txg);
1327 db->db_dirtycnt += 1;
1328 ASSERT3U(db->db_dirtycnt, <=, 3);
1329
1330 mutex_exit(&db->db_mtx);
1331
1332 if (db->db_blkid == DMU_BONUS_BLKID ||
1333 db->db_blkid == DMU_SPILL_BLKID) {
1334 mutex_enter(&dn->dn_mtx);
1335 ASSERT(!list_link_active(&dr->dr_dirty_node));
1336 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1337 mutex_exit(&dn->dn_mtx);
1338 dnode_setdirty(dn, tx);
1339 DB_DNODE_EXIT(db);
1340 return (dr);
1341 } else if (do_free_accounting) {
1342 blkptr_t *bp = db->db_blkptr;
1343 int64_t willfree = (bp && !BP_IS_HOLE(bp)) ?
1344 bp_get_dsize(os->os_spa, bp) : db->db.db_size;
1345 /*
1346 * This is only a guess -- if the dbuf is dirty
1347 * in a previous txg, we don't know how much
1348 * space it will use on disk yet. We should
1349 * really have the struct_rwlock to access
1350 * db_blkptr, but since this is just a guess,
1351 * it's OK if we get an odd answer.
1352 */
1353 ddt_prefetch(os->os_spa, bp);
1354 dnode_willuse_space(dn, -willfree, tx);
1355 }
1356
1357 if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
1358 rw_enter(&dn->dn_struct_rwlock, RW_READER);
1359 drop_struct_lock = TRUE;
1360 }
1361
1362 if (db->db_level == 0) {
1363 dnode_new_blkid(dn, db->db_blkid, tx, drop_struct_lock);
1364 ASSERT(dn->dn_maxblkid >= db->db_blkid);
1365 }
1366
1367 if (db->db_level+1 < dn->dn_nlevels) {
1368 dmu_buf_impl_t *parent = db->db_parent;
1369 dbuf_dirty_record_t *di;
1370 int parent_held = FALSE;
1371
1372 if (db->db_parent == NULL || db->db_parent == dn->dn_dbuf) {
1373 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1374
1375 parent = dbuf_hold_level(dn, db->db_level+1,
1376 db->db_blkid >> epbs, FTAG);
1377 ASSERT(parent != NULL);
1378 parent_held = TRUE;
1379 }
1380 if (drop_struct_lock)
1381 rw_exit(&dn->dn_struct_rwlock);
1382 ASSERT3U(db->db_level+1, ==, parent->db_level);
1383 di = dbuf_dirty(parent, tx);
1384 if (parent_held)
1385 dbuf_rele(parent, FTAG);
1386
1387 mutex_enter(&db->db_mtx);
1388 /*
1389 * Since we've dropped the mutex, it's possible that
1390 * dbuf_undirty() might have changed this out from under us.
1391 */
1392 if (db->db_last_dirty == dr ||
1393 dn->dn_object == DMU_META_DNODE_OBJECT) {
1394 mutex_enter(&di->dt.di.dr_mtx);
1395 ASSERT3U(di->dr_txg, ==, tx->tx_txg);
1396 ASSERT(!list_link_active(&dr->dr_dirty_node));
1397 list_insert_tail(&di->dt.di.dr_children, dr);
1398 mutex_exit(&di->dt.di.dr_mtx);
1399 dr->dr_parent = di;
1400 }
1401 mutex_exit(&db->db_mtx);
1402 } else {
1403 ASSERT(db->db_level+1 == dn->dn_nlevels);
1404 ASSERT(db->db_blkid < dn->dn_nblkptr);
1405 ASSERT(db->db_parent == NULL || db->db_parent == dn->dn_dbuf);
1406 mutex_enter(&dn->dn_mtx);
1407 ASSERT(!list_link_active(&dr->dr_dirty_node));
1408 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1409 mutex_exit(&dn->dn_mtx);
1410 if (drop_struct_lock)
1411 rw_exit(&dn->dn_struct_rwlock);
1412 }
1413
1414 dnode_setdirty(dn, tx);
1415 DB_DNODE_EXIT(db);
1416 return (dr);
1417 }
1418
1419 /*
1420 * Undirty a buffer in the transaction group referenced by the given
1421 * transaction. Return whether this evicted the dbuf.
1422 */
1423 static boolean_t
1424 dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1425 {
1426 dnode_t *dn;
1427 uint64_t txg = tx->tx_txg;
1428 dbuf_dirty_record_t *dr, **drp;
1429
1430 ASSERT(txg != 0);
1431
1432 /*
1433 * Due to our use of dn_nlevels below, this can only be called
1434 * in open context, unless we are operating on the MOS.
1435 * From syncing context, dn_nlevels may be different from the
1436 * dn_nlevels used when dbuf was dirtied.
1437 */
1438 ASSERT(db->db_objset ==
1439 dmu_objset_pool(db->db_objset)->dp_meta_objset ||
1440 txg != spa_syncing_txg(dmu_objset_spa(db->db_objset)));
1441 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1442 ASSERT0(db->db_level);
1443 ASSERT(MUTEX_HELD(&db->db_mtx));
1444
1445 /*
1446 * If this buffer is not dirty, we're done.
1447 */
1448 for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next)
1449 if (dr->dr_txg <= txg)
1450 break;
1451 if (dr == NULL || dr->dr_txg < txg)
1452 return (B_FALSE);
1453 ASSERT(dr->dr_txg == txg);
1454 ASSERT(dr->dr_dbuf == db);
1455
1456 DB_DNODE_ENTER(db);
1457 dn = DB_DNODE(db);
1458
1459 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1460
1461 ASSERT(db->db.db_size != 0);
1462
1463 dsl_pool_undirty_space(dmu_objset_pool(dn->dn_objset),
1464 dr->dr_accounted, txg);
1465
1466 *drp = dr->dr_next;
1467
1468 /*
1469 * Note that there are three places in dbuf_dirty()
1470 * where this dirty record may be put on a list.
1471 * Make sure to do a list_remove corresponding to
1472 * every one of those list_insert calls.
1473 */
1474 if (dr->dr_parent) {
1475 mutex_enter(&dr->dr_parent->dt.di.dr_mtx);
1476 list_remove(&dr->dr_parent->dt.di.dr_children, dr);
1477 mutex_exit(&dr->dr_parent->dt.di.dr_mtx);
1478 } else if (db->db_blkid == DMU_SPILL_BLKID ||
1479 db->db_level + 1 == dn->dn_nlevels) {
1480 ASSERT(db->db_blkptr == NULL || db->db_parent == dn->dn_dbuf);
1481 mutex_enter(&dn->dn_mtx);
1482 list_remove(&dn->dn_dirty_records[txg & TXG_MASK], dr);
1483 mutex_exit(&dn->dn_mtx);
1484 }
1485 DB_DNODE_EXIT(db);
1486
1487 if (db->db_state != DB_NOFILL) {
1488 dbuf_unoverride(dr);
1489
1490 ASSERT(db->db_buf != NULL);
1491 ASSERT(dr->dt.dl.dr_data != NULL);
1492 if (dr->dt.dl.dr_data != db->db_buf)
1493 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data, db));
1494 }
1495
1496 kmem_free(dr, sizeof (dbuf_dirty_record_t));
1497
1498 ASSERT(db->db_dirtycnt > 0);
1499 db->db_dirtycnt -= 1;
1500
1501 if (refcount_remove(&db->db_holds, (void *)(uintptr_t)txg) == 0) {
1502 arc_buf_t *buf = db->db_buf;
1503
1504 ASSERT(db->db_state == DB_NOFILL || arc_released(buf));
1505 dbuf_clear_data(db);
1506 VERIFY(arc_buf_remove_ref(buf, db));
1507 dbuf_evict(db);
1508 return (B_TRUE);
1509 }
1510
1511 return (B_FALSE);
1512 }
1513
1514 void
1515 dmu_buf_will_dirty(dmu_buf_t *db_fake, dmu_tx_t *tx)
1516 {
1517 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1518 int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH;
1519
1520 ASSERT(tx->tx_txg != 0);
1521 ASSERT(!refcount_is_zero(&db->db_holds));
1522
1523 /*
1524 * Quick check for dirtyness. For already dirty blocks, this
1525 * reduces runtime of this function by >90%, and overall performance
1526 * by 50% for some workloads (e.g. file deletion with indirect blocks
1527 * cached).
1528 */
1529 mutex_enter(&db->db_mtx);
1530 dbuf_dirty_record_t *dr;
1531 for (dr = db->db_last_dirty;
1532 dr != NULL && dr->dr_txg >= tx->tx_txg; dr = dr->dr_next) {
1533 /*
1534 * It's possible that it is already dirty but not cached,
1535 * because there are some calls to dbuf_dirty() that don't
1536 * go through dmu_buf_will_dirty().
1537 */
1538 if (dr->dr_txg == tx->tx_txg && db->db_state == DB_CACHED) {
1539 /* This dbuf is already dirty and cached. */
1540 dbuf_redirty(dr);
1541 mutex_exit(&db->db_mtx);
1542 return;
1543 }
1544 }
1545 mutex_exit(&db->db_mtx);
1546
1547 DB_DNODE_ENTER(db);
1548 if (RW_WRITE_HELD(&DB_DNODE(db)->dn_struct_rwlock))
1549 rf |= DB_RF_HAVESTRUCT;
1550 DB_DNODE_EXIT(db);
1551 (void) dbuf_read(db, NULL, rf);
1552 (void) dbuf_dirty(db, tx);
1553 }
1554
1555 void
1556 dmu_buf_will_not_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1557 {
1558 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1559
1560 db->db_state = DB_NOFILL;
1561
1562 dmu_buf_will_fill(db_fake, tx);
1563 }
1564
1565 void
1566 dmu_buf_will_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1567 {
1568 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1569
1570 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1571 ASSERT(tx->tx_txg != 0);
1572 ASSERT(db->db_level == 0);
1573 ASSERT(!refcount_is_zero(&db->db_holds));
1574
1575 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT ||
1576 dmu_tx_private_ok(tx));
1577
1578 dbuf_noread(db);
1579 (void) dbuf_dirty(db, tx);
1580 }
1581
1582 #pragma weak dmu_buf_fill_done = dbuf_fill_done
1583 /* ARGSUSED */
1584 void
1585 dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx)
1586 {
1587 mutex_enter(&db->db_mtx);
1588 DBUF_VERIFY(db);
1589
1590 if (db->db_state == DB_FILL) {
1591 if (db->db_level == 0 && db->db_freed_in_flight) {
1592 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1593 /* we were freed while filling */
1594 /* XXX dbuf_undirty? */
1595 bzero(db->db.db_data, db->db.db_size);
1596 db->db_freed_in_flight = FALSE;
1597 }
1598 db->db_state = DB_CACHED;
1599 cv_broadcast(&db->db_changed);
1600 }
1601 mutex_exit(&db->db_mtx);
1602 }
1603
1604 void
1605 dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
1606 bp_embedded_type_t etype, enum zio_compress comp,
1607 int uncompressed_size, int compressed_size, int byteorder,
1608 dmu_tx_t *tx)
1609 {
1610 dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf;
1611 struct dirty_leaf *dl;
1612 dmu_object_type_t type;
1613
1614 if (etype == BP_EMBEDDED_TYPE_DATA) {
1615 ASSERT(spa_feature_is_active(dmu_objset_spa(db->db_objset),
1616 SPA_FEATURE_EMBEDDED_DATA));
1617 }
1618
1619 DB_DNODE_ENTER(db);
1620 type = DB_DNODE(db)->dn_type;
1621 DB_DNODE_EXIT(db);
1622
1623 ASSERT0(db->db_level);
1624 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1625
1626 dmu_buf_will_not_fill(dbuf, tx);
1627
1628 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
1629 dl = &db->db_last_dirty->dt.dl;
1630 encode_embedded_bp_compressed(&dl->dr_overridden_by,
1631 data, comp, uncompressed_size, compressed_size);
1632 BPE_SET_ETYPE(&dl->dr_overridden_by, etype);
1633 BP_SET_TYPE(&dl->dr_overridden_by, type);
1634 BP_SET_LEVEL(&dl->dr_overridden_by, 0);
1635 BP_SET_BYTEORDER(&dl->dr_overridden_by, byteorder);
1636
1637 dl->dr_override_state = DR_OVERRIDDEN;
1638 dl->dr_overridden_by.blk_birth = db->db_last_dirty->dr_txg;
1639 }
1640
1641 /*
1642 * Directly assign a provided arc buf to a given dbuf if it's not referenced
1643 * by anybody except our caller. Otherwise copy arcbuf's contents to dbuf.
1644 */
1645 void
1646 dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx)
1647 {
1648 ASSERT(!refcount_is_zero(&db->db_holds));
1649 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1650 ASSERT(db->db_level == 0);
1651 ASSERT(DBUF_GET_BUFC_TYPE(db) == ARC_BUFC_DATA);
1652 ASSERT(buf != NULL);
1653 ASSERT(arc_buf_size(buf) == db->db.db_size);
1654 ASSERT(tx->tx_txg != 0);
1655
1656 arc_return_buf(buf, db);
1657 ASSERT(arc_released(buf));
1658
1659 mutex_enter(&db->db_mtx);
1660
1661 while (db->db_state == DB_READ || db->db_state == DB_FILL)
1662 cv_wait(&db->db_changed, &db->db_mtx);
1663
1664 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED);
1665
1666 if (db->db_state == DB_CACHED &&
1667 refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) {
1668 mutex_exit(&db->db_mtx);
1669 (void) dbuf_dirty(db, tx);
1670 bcopy(buf->b_data, db->db.db_data, db->db.db_size);
1671 VERIFY(arc_buf_remove_ref(buf, db));
1672 xuio_stat_wbuf_copied();
1673 return;
1674 }
1675
1676 xuio_stat_wbuf_nocopy();
1677 if (db->db_state == DB_CACHED) {
1678 dbuf_dirty_record_t *dr = db->db_last_dirty;
1679
1680 ASSERT(db->db_buf != NULL);
1681 if (dr != NULL && dr->dr_txg == tx->tx_txg) {
1682 ASSERT(dr->dt.dl.dr_data == db->db_buf);
1683 if (!arc_released(db->db_buf)) {
1684 ASSERT(dr->dt.dl.dr_override_state ==
1685 DR_OVERRIDDEN);
1686 arc_release(db->db_buf, db);
1687 }
1688 dr->dt.dl.dr_data = buf;
1689 VERIFY(arc_buf_remove_ref(db->db_buf, db));
1690 } else if (dr == NULL || dr->dt.dl.dr_data != db->db_buf) {
1691 arc_release(db->db_buf, db);
1692 VERIFY(arc_buf_remove_ref(db->db_buf, db));
1693 }
1694 db->db_buf = NULL;
1695 }
1696 ASSERT(db->db_buf == NULL);
1697 dbuf_set_data(db, buf);
1698 db->db_state = DB_FILL;
1699 mutex_exit(&db->db_mtx);
1700 (void) dbuf_dirty(db, tx);
1701 dmu_buf_fill_done(&db->db, tx);
1702 }
1703
1704 /*
1705 * "Clear" the contents of this dbuf. This will mark the dbuf
1706 * EVICTING and clear *most* of its references. Unfortunately,
1707 * when we are not holding the dn_dbufs_mtx, we can't clear the
1708 * entry in the dn_dbufs list. We have to wait until dbuf_destroy()
1709 * in this case. For callers from the DMU we will usually see:
1710 * dbuf_clear()->arc_clear_callback()->dbuf_do_evict()->dbuf_destroy()
1711 * For the arc callback, we will usually see:
1712 * dbuf_do_evict()->dbuf_clear();dbuf_destroy()
1713 * Sometimes, though, we will get a mix of these two:
1714 * DMU: dbuf_clear()->arc_clear_callback()
1715 * ARC: dbuf_do_evict()->dbuf_destroy()
1716 *
1717 * This routine will dissociate the dbuf from the arc, by calling
1718 * arc_clear_callback(), but will not evict the data from the ARC.
1719 */
1720 void
1721 dbuf_clear(dmu_buf_impl_t *db)
1722 {
1723 dnode_t *dn;
1724 dmu_buf_impl_t *parent = db->db_parent;
1725 dmu_buf_impl_t *dndb;
1726 boolean_t dbuf_gone = B_FALSE;
1727
1728 ASSERT(MUTEX_HELD(&db->db_mtx));
1729 ASSERT(refcount_is_zero(&db->db_holds));
1730
1731 dbuf_evict_user(db);
1732
1733 if (db->db_state == DB_CACHED) {
1734 ASSERT(db->db.db_data != NULL);
1735 if (db->db_blkid == DMU_BONUS_BLKID) {
1736 zio_buf_free(db->db.db_data, DN_MAX_BONUSLEN);
1737 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
1738 }
1739 db->db.db_data = NULL;
1740 db->db_state = DB_UNCACHED;
1741 }
1742
1743 ASSERT(db->db_state == DB_UNCACHED || db->db_state == DB_NOFILL);
1744 ASSERT(db->db_data_pending == NULL);
1745
1746 db->db_state = DB_EVICTING;
1747 db->db_blkptr = NULL;
1748
1749 DB_DNODE_ENTER(db);
1750 dn = DB_DNODE(db);
1751 dndb = dn->dn_dbuf;
1752 if (db->db_blkid != DMU_BONUS_BLKID && MUTEX_HELD(&dn->dn_dbufs_mtx)) {
1753 avl_remove(&dn->dn_dbufs, db);
1754 atomic_dec_32(&dn->dn_dbufs_count);
1755 membar_producer();
1756 DB_DNODE_EXIT(db);
1757 /*
1758 * Decrementing the dbuf count means that the hold corresponding
1759 * to the removed dbuf is no longer discounted in dnode_move(),
1760 * so the dnode cannot be moved until after we release the hold.
1761 * The membar_producer() ensures visibility of the decremented
1762 * value in dnode_move(), since DB_DNODE_EXIT doesn't actually
1763 * release any lock.
1764 */
1765 dnode_rele(dn, db);
1766 db->db_dnode_handle = NULL;
1767 } else {
1768 DB_DNODE_EXIT(db);
1769 }
1770
1771 if (db->db_buf)
1772 dbuf_gone = arc_clear_callback(db->db_buf);
1773
1774 if (!dbuf_gone)
1775 mutex_exit(&db->db_mtx);
1776
1777 /*
1778 * If this dbuf is referenced from an indirect dbuf,
1779 * decrement the ref count on the indirect dbuf.
1780 */
1781 if (parent && parent != dndb)
1782 dbuf_rele(parent, db);
1783 }
1784
1785 /*
1786 * Note: While bpp will always be updated if the function returns success,
1787 * parentp will not be updated if the dnode does not have dn_dbuf filled in;
1788 * this happens when the dnode is the meta-dnode, or a userused or groupused
1789 * object.
1790 */
1791 static int
1792 dbuf_findbp(dnode_t *dn, int level, uint64_t blkid, int fail_sparse,
1793 dmu_buf_impl_t **parentp, blkptr_t **bpp)
1794 {
1795 int nlevels, epbs;
1796
1797 *parentp = NULL;
1798 *bpp = NULL;
1799
1800 ASSERT(blkid != DMU_BONUS_BLKID);
1801
1802 if (blkid == DMU_SPILL_BLKID) {
1803 mutex_enter(&dn->dn_mtx);
1804 if (dn->dn_have_spill &&
1805 (dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR))
1806 *bpp = &dn->dn_phys->dn_spill;
1807 else
1808 *bpp = NULL;
1809 dbuf_add_ref(dn->dn_dbuf, NULL);
1810 *parentp = dn->dn_dbuf;
1811 mutex_exit(&dn->dn_mtx);
1812 return (0);
1813 }
1814
1815 if (dn->dn_phys->dn_nlevels == 0)
1816 nlevels = 1;
1817 else
1818 nlevels = dn->dn_phys->dn_nlevels;
1819
1820 epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1821
1822 ASSERT3U(level * epbs, <, 64);
1823 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1824 if (level >= nlevels ||
1825 (blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))) {
1826 /* the buffer has no parent yet */
1827 return (SET_ERROR(ENOENT));
1828 } else if (level < nlevels-1) {
1829 /* this block is referenced from an indirect block */
1830 int err = dbuf_hold_impl(dn, level+1,
1831 blkid >> epbs, fail_sparse, FALSE, NULL, parentp);
1832 if (err)
1833 return (err);
1834 err = dbuf_read(*parentp, NULL,
1835 (DB_RF_HAVESTRUCT | DB_RF_NOPREFETCH | DB_RF_CANFAIL));
1836 if (err) {
1837 dbuf_rele(*parentp, NULL);
1838 *parentp = NULL;
1839 return (err);
1840 }
1841 *bpp = ((blkptr_t *)(*parentp)->db.db_data) +
1842 (blkid & ((1ULL << epbs) - 1));
1843 return (0);
1844 } else {
1845 /* the block is referenced from the dnode */
1846 ASSERT3U(level, ==, nlevels-1);
1847 ASSERT(dn->dn_phys->dn_nblkptr == 0 ||
1848 blkid < dn->dn_phys->dn_nblkptr);
1849 if (dn->dn_dbuf) {
1850 dbuf_add_ref(dn->dn_dbuf, NULL);
1851 *parentp = dn->dn_dbuf;
1852 }
1853 *bpp = &dn->dn_phys->dn_blkptr[blkid];
1854 return (0);
1855 }
1856 }
1857
1858 static dmu_buf_impl_t *
1859 dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid,
1860 dmu_buf_impl_t *parent, blkptr_t *blkptr)
1861 {
1862 objset_t *os = dn->dn_objset;
1863 dmu_buf_impl_t *db, *odb;
1864
1865 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1866 ASSERT(dn->dn_type != DMU_OT_NONE);
1867
1868 db = kmem_cache_alloc(dbuf_cache, KM_SLEEP);
1869
1870 db->db_objset = os;
1871 db->db.db_object = dn->dn_object;
1872 db->db_level = level;
1873 db->db_blkid = blkid;
1874 db->db_last_dirty = NULL;
1875 db->db_dirtycnt = 0;
1876 db->db_dnode_handle = dn->dn_handle;
1877 db->db_parent = parent;
1878 db->db_blkptr = blkptr;
1879
1880 db->db_user = NULL;
1881 db->db_user_immediate_evict = FALSE;
1882 db->db_freed_in_flight = FALSE;
1883 db->db_pending_evict = FALSE;
1884
1885 if (blkid == DMU_BONUS_BLKID) {
1886 ASSERT3P(parent, ==, dn->dn_dbuf);
1887 db->db.db_size = DN_MAX_BONUSLEN -
1888 (dn->dn_nblkptr-1) * sizeof (blkptr_t);
1889 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
1890 db->db.db_offset = DMU_BONUS_BLKID;
1891 db->db_state = DB_UNCACHED;
1892 /* the bonus dbuf is not placed in the hash table */
1893 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1894 return (db);
1895 } else if (blkid == DMU_SPILL_BLKID) {
1896 db->db.db_size = (blkptr != NULL) ?
1897 BP_GET_LSIZE(blkptr) : SPA_MINBLOCKSIZE;
1898 db->db.db_offset = 0;
1899 } else {
1900 int blocksize =
1901 db->db_level ? 1 << dn->dn_indblkshift : dn->dn_datablksz;
1902 db->db.db_size = blocksize;
1903 db->db.db_offset = db->db_blkid * blocksize;
1904 }
1905
1906 /*
1907 * Hold the dn_dbufs_mtx while we get the new dbuf
1908 * in the hash table *and* added to the dbufs list.
1909 * This prevents a possible deadlock with someone
1910 * trying to look up this dbuf before its added to the
1911 * dn_dbufs list.
1912 */
1913 mutex_enter(&dn->dn_dbufs_mtx);
1914 db->db_state = DB_EVICTING;
1915 if ((odb = dbuf_hash_insert(db)) != NULL) {
1916 /* someone else inserted it first */
1917 kmem_cache_free(dbuf_cache, db);
1918 mutex_exit(&dn->dn_dbufs_mtx);
1919 return (odb);
1920 }
1921 avl_add(&dn->dn_dbufs, db);
1922 if (db->db_level == 0 && db->db_blkid >=
1923 dn->dn_unlisted_l0_blkid)
1924 dn->dn_unlisted_l0_blkid = db->db_blkid + 1;
1925 db->db_state = DB_UNCACHED;
1926 mutex_exit(&dn->dn_dbufs_mtx);
1927 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1928
1929 if (parent && parent != dn->dn_dbuf)
1930 dbuf_add_ref(parent, db);
1931
1932 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1933 refcount_count(&dn->dn_holds) > 0);
1934 (void) refcount_add(&dn->dn_holds, db);
1935 atomic_inc_32(&dn->dn_dbufs_count);
1936
1937 dprintf_dbuf(db, "db=%p\n", db);
1938
1939 return (db);
1940 }
1941
1942 static int
1943 dbuf_do_evict(void *private)
1944 {
1945 dmu_buf_impl_t *db = private;
1946
1947 if (!MUTEX_HELD(&db->db_mtx))
1948 mutex_enter(&db->db_mtx);
1949
1950 ASSERT(refcount_is_zero(&db->db_holds));
1951
1952 if (db->db_state != DB_EVICTING) {
1953 ASSERT(db->db_state == DB_CACHED);
1954 DBUF_VERIFY(db);
1955 db->db_buf = NULL;
1956 dbuf_evict(db);
1957 } else {
1958 mutex_exit(&db->db_mtx);
1959 dbuf_destroy(db);
1960 }
1961 return (0);
1962 }
1963
1964 static void
1965 dbuf_destroy(dmu_buf_impl_t *db)
1966 {
1967 ASSERT(refcount_is_zero(&db->db_holds));
1968
1969 if (db->db_blkid != DMU_BONUS_BLKID) {
1970 /*
1971 * If this dbuf is still on the dn_dbufs list,
1972 * remove it from that list.
1973 */
1974 if (db->db_dnode_handle != NULL) {
1975 dnode_t *dn;
1976
1977 DB_DNODE_ENTER(db);
1978 dn = DB_DNODE(db);
1979 mutex_enter(&dn->dn_dbufs_mtx);
1980 avl_remove(&dn->dn_dbufs, db);
1981 atomic_dec_32(&dn->dn_dbufs_count);
1982 mutex_exit(&dn->dn_dbufs_mtx);
1983 DB_DNODE_EXIT(db);
1984 /*
1985 * Decrementing the dbuf count means that the hold
1986 * corresponding to the removed dbuf is no longer
1987 * discounted in dnode_move(), so the dnode cannot be
1988 * moved until after we release the hold.
1989 */
1990 dnode_rele(dn, db);
1991 db->db_dnode_handle = NULL;
1992 }
1993 dbuf_hash_remove(db);
1994 }
1995 db->db_parent = NULL;
1996 db->db_buf = NULL;
1997
1998 ASSERT(db->db.db_data == NULL);
1999 ASSERT(db->db_hash_next == NULL);
2000 ASSERT(db->db_blkptr == NULL);
2001 ASSERT(db->db_data_pending == NULL);
2002
2003 kmem_cache_free(dbuf_cache, db);
2004 arc_space_return(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
2005 }
2006
2007 typedef struct dbuf_prefetch_arg {
2008 spa_t *dpa_spa; /* The spa to issue the prefetch in. */
2009 zbookmark_phys_t dpa_zb; /* The target block to prefetch. */
2010 int dpa_epbs; /* Entries (blkptr_t's) Per Block Shift. */
2011 int dpa_curlevel; /* The current level that we're reading */
2012 zio_priority_t dpa_prio; /* The priority I/Os should be issued at. */
2013 zio_t *dpa_zio; /* The parent zio_t for all prefetches. */
2014 arc_flags_t dpa_aflags; /* Flags to pass to the final prefetch. */
2015 } dbuf_prefetch_arg_t;
2016
2017 /*
2018 * Actually issue the prefetch read for the block given.
2019 */
2020 static void
2021 dbuf_issue_final_prefetch(dbuf_prefetch_arg_t *dpa, blkptr_t *bp)
2022 {
2023 if (BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp))
2024 return;
2025
2026 arc_flags_t aflags =
2027 dpa->dpa_aflags | ARC_FLAG_NOWAIT | ARC_FLAG_PREFETCH;
2028
2029 ASSERT3U(dpa->dpa_curlevel, ==, BP_GET_LEVEL(bp));
2030 ASSERT3U(dpa->dpa_curlevel, ==, dpa->dpa_zb.zb_level);
2031 ASSERT(dpa->dpa_zio != NULL);
2032 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa, bp, NULL, NULL,
2033 dpa->dpa_prio, ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
2034 &aflags, &dpa->dpa_zb);
2035 }
2036
2037 /*
2038 * Called when an indirect block above our prefetch target is read in. This
2039 * will either read in the next indirect block down the tree or issue the actual
2040 * prefetch if the next block down is our target.
2041 */
2042 static void
2043 dbuf_prefetch_indirect_done(zio_t *zio, arc_buf_t *abuf, void *private)
2044 {
2045 dbuf_prefetch_arg_t *dpa = private;
2046
2047 ASSERT3S(dpa->dpa_zb.zb_level, <, dpa->dpa_curlevel);
2048 ASSERT3S(dpa->dpa_curlevel, >, 0);
2049 if (zio != NULL) {
2050 ASSERT3S(BP_GET_LEVEL(zio->io_bp), ==, dpa->dpa_curlevel);
2051 ASSERT3U(BP_GET_LSIZE(zio->io_bp), ==, zio->io_size);
2052 ASSERT3P(zio->io_spa, ==, dpa->dpa_spa);
2053 }
2054
2055 dpa->dpa_curlevel--;
2056
2057 uint64_t nextblkid = dpa->dpa_zb.zb_blkid >>
2058 (dpa->dpa_epbs * (dpa->dpa_curlevel - dpa->dpa_zb.zb_level));
2059 blkptr_t *bp = ((blkptr_t *)abuf->b_data) +
2060 P2PHASE(nextblkid, 1ULL << dpa->dpa_epbs);
2061 if (BP_IS_HOLE(bp) || (zio != NULL && zio->io_error != 0)) {
2062 kmem_free(dpa, sizeof (*dpa));
2063 } else if (dpa->dpa_curlevel == dpa->dpa_zb.zb_level) {
2064 ASSERT3U(nextblkid, ==, dpa->dpa_zb.zb_blkid);
2065 dbuf_issue_final_prefetch(dpa, bp);
2066 kmem_free(dpa, sizeof (*dpa));
2067 } else {
2068 arc_flags_t iter_aflags = ARC_FLAG_NOWAIT;
2069 zbookmark_phys_t zb;
2070
2071 ASSERT3U(dpa->dpa_curlevel, ==, BP_GET_LEVEL(bp));
2072
2073 SET_BOOKMARK(&zb, dpa->dpa_zb.zb_objset,
2074 dpa->dpa_zb.zb_object, dpa->dpa_curlevel, nextblkid);
2075
2076 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa,
2077 bp, dbuf_prefetch_indirect_done, dpa, dpa->dpa_prio,
2078 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
2079 &iter_aflags, &zb);
2080 }
2081 (void) arc_buf_remove_ref(abuf, private);
2082 }
2083
2084 /*
2085 * Issue prefetch reads for the given block on the given level. If the indirect
2086 * blocks above that block are not in memory, we will read them in
2087 * asynchronously. As a result, this call never blocks waiting for a read to
2088 * complete.
2089 */
2090 void
2091 dbuf_prefetch(dnode_t *dn, int64_t level, uint64_t blkid, zio_priority_t prio,
2092 arc_flags_t aflags)
2093 {
2094 blkptr_t bp;
2095 int epbs, nlevels, curlevel;
2096 uint64_t curblkid;
2097
2098 ASSERT(blkid != DMU_BONUS_BLKID);
2099 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
2100
2101 if (blkid > dn->dn_maxblkid)
2102 return;
2103
2104 if (dnode_block_freed(dn, blkid))
2105 return;
2106
2107 /*
2108 * This dnode hasn't been written to disk yet, so there's nothing to
2109 * prefetch.
2110 */
2111 nlevels = dn->dn_phys->dn_nlevels;
2112 if (level >= nlevels || dn->dn_phys->dn_nblkptr == 0)
2113 return;
2114
2115 epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2116 if (dn->dn_phys->dn_maxblkid < blkid << (epbs * level))
2117 return;
2118
2119 dmu_buf_impl_t *db = dbuf_find(dn->dn_objset, dn->dn_object,
2120 level, blkid);
2121 if (db != NULL) {
2122 mutex_exit(&db->db_mtx);
2123 /*
2124 * This dbuf already exists. It is either CACHED, or
2125 * (we assume) about to be read or filled.
2126 */
2127 return;
2128 }
2129
2130 /*
2131 * Find the closest ancestor (indirect block) of the target block
2132 * that is present in the cache. In this indirect block, we will
2133 * find the bp that is at curlevel, curblkid.
2134 */
2135 curlevel = level;
2136 curblkid = blkid;
2137 while (curlevel < nlevels - 1) {
2138 int parent_level = curlevel + 1;
2139 uint64_t parent_blkid = curblkid >> epbs;
2140 dmu_buf_impl_t *db;
2141
2142 if (dbuf_hold_impl(dn, parent_level, parent_blkid,
2143 FALSE, TRUE, FTAG, &db) == 0) {
2144 blkptr_t *bpp = db->db_buf->b_data;
2145 bp = bpp[P2PHASE(curblkid, 1 << epbs)];
2146 dbuf_rele(db, FTAG);
2147 break;
2148 }
2149
2150 curlevel = parent_level;
2151 curblkid = parent_blkid;
2152 }
2153
2154 if (curlevel == nlevels - 1) {
2155 /* No cached indirect blocks found. */
2156 ASSERT3U(curblkid, <, dn->dn_phys->dn_nblkptr);
2157 bp = dn->dn_phys->dn_blkptr[curblkid];
2158 }
2159 if (BP_IS_HOLE(&bp))
2160 return;
2161
2162 ASSERT3U(curlevel, ==, BP_GET_LEVEL(&bp));
2163
2164 zio_t *pio = zio_root(dmu_objset_spa(dn->dn_objset), NULL, NULL,
2165 ZIO_FLAG_CANFAIL);
2166
2167 dbuf_prefetch_arg_t *dpa = kmem_zalloc(sizeof (*dpa), KM_SLEEP);
2168 dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset;
2169 SET_BOOKMARK(&dpa->dpa_zb, ds != NULL ? ds->ds_object : DMU_META_OBJSET,
2170 dn->dn_object, level, blkid);
2171 dpa->dpa_curlevel = curlevel;
2172 dpa->dpa_prio = prio;
2173 dpa->dpa_aflags = aflags;
2174 dpa->dpa_spa = dn->dn_objset->os_spa;
2175 dpa->dpa_epbs = epbs;
2176 dpa->dpa_zio = pio;
2177
2178 /*
2179 * If we have the indirect just above us, no need to do the asynchronous
2180 * prefetch chain; we'll just run the last step ourselves. If we're at
2181 * a higher level, though, we want to issue the prefetches for all the
2182 * indirect blocks asynchronously, so we can go on with whatever we were
2183 * doing.
2184 */
2185 if (curlevel == level) {
2186 ASSERT3U(curblkid, ==, blkid);
2187 dbuf_issue_final_prefetch(dpa, &bp);
2188 kmem_free(dpa, sizeof (*dpa));
2189 } else {
2190 arc_flags_t iter_aflags = ARC_FLAG_NOWAIT;
2191 zbookmark_phys_t zb;
2192
2193 SET_BOOKMARK(&zb, ds != NULL ? ds->ds_object : DMU_META_OBJSET,
2194 dn->dn_object, curlevel, curblkid);
2195 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa,
2196 &bp, dbuf_prefetch_indirect_done, dpa, prio,
2197 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
2198 &iter_aflags, &zb);
2199 }
2200 /*
2201 * We use pio here instead of dpa_zio since it's possible that
2202 * dpa may have already been freed.
2203 */
2204 zio_nowait(pio);
2205 }
2206
2207 /*
2208 * Returns with db_holds incremented, and db_mtx not held.
2209 * Note: dn_struct_rwlock must be held.
2210 */
2211 int
2212 dbuf_hold_impl(dnode_t *dn, uint8_t level, uint64_t blkid,
2213 boolean_t fail_sparse, boolean_t fail_uncached,
2214 void *tag, dmu_buf_impl_t **dbp)
2215 {
2216 dmu_buf_impl_t *db, *parent = NULL;
2217
2218 ASSERT(blkid != DMU_BONUS_BLKID);
2219 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
2220 ASSERT3U(dn->dn_nlevels, >, level);
2221
2222 *dbp = NULL;
2223 top:
2224 /* dbuf_find() returns with db_mtx held */
2225 db = dbuf_find(dn->dn_objset, dn->dn_object, level, blkid);
2226
2227 if (db == NULL) {
2228 blkptr_t *bp = NULL;
2229 int err;
2230
2231 if (fail_uncached)
2232 return (SET_ERROR(ENOENT));
2233
2234 ASSERT3P(parent, ==, NULL);
2235 err = dbuf_findbp(dn, level, blkid, fail_sparse, &parent, &bp);
2236 if (fail_sparse) {
2237 if (err == 0 && bp && BP_IS_HOLE(bp))
2238 err = SET_ERROR(ENOENT);
2239 if (err) {
2240 if (parent)
2241 dbuf_rele(parent, NULL);
2242 return (err);
2243 }
2244 }
2245 if (err && err != ENOENT)
2246 return (err);
2247 db = dbuf_create(dn, level, blkid, parent, bp);
2248 }
2249
2250 if (fail_uncached && db->db_state != DB_CACHED) {
2251 mutex_exit(&db->db_mtx);
2252 return (SET_ERROR(ENOENT));
2253 }
2254
2255 if (db->db_buf && refcount_is_zero(&db->db_holds)) {
2256 arc_buf_add_ref(db->db_buf, db);
2257 if (db->db_buf->b_data == NULL) {
2258 dbuf_clear(db);
2259 if (parent) {
2260 dbuf_rele(parent, NULL);
2261 parent = NULL;
2262 }
2263 goto top;
2264 }
2265 ASSERT3P(db->db.db_data, ==, db->db_buf->b_data);
2266 }
2267
2268 ASSERT(db->db_buf == NULL || arc_referenced(db->db_buf));
2269
2270 /*
2271 * If this buffer is currently syncing out, and we are are
2272 * still referencing it from db_data, we need to make a copy
2273 * of it in case we decide we want to dirty it again in this txg.
2274 */
2275 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
2276 dn->dn_object != DMU_META_DNODE_OBJECT &&
2277 db->db_state == DB_CACHED && db->db_data_pending) {
2278 dbuf_dirty_record_t *dr = db->db_data_pending;
2279
2280 if (dr->dt.dl.dr_data == db->db_buf) {
2281 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
2282
2283 dbuf_set_data(db,
2284 arc_buf_alloc(dn->dn_objset->os_spa,
2285 db->db.db_size, db, type));
2286 bcopy(dr->dt.dl.dr_data->b_data, db->db.db_data,
2287 db->db.db_size);
2288 }
2289 }
2290
2291 (void) refcount_add(&db->db_holds, tag);
2292 DBUF_VERIFY(db);
2293 mutex_exit(&db->db_mtx);
2294
2295 /* NOTE: we can't rele the parent until after we drop the db_mtx */
2296 if (parent)
2297 dbuf_rele(parent, NULL);
2298
2299 ASSERT3P(DB_DNODE(db), ==, dn);
2300 ASSERT3U(db->db_blkid, ==, blkid);
2301 ASSERT3U(db->db_level, ==, level);
2302 *dbp = db;
2303
2304 return (0);
2305 }
2306
2307 dmu_buf_impl_t *
2308 dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag)
2309 {
2310 return (dbuf_hold_level(dn, 0, blkid, tag));
2311 }
2312
2313 dmu_buf_impl_t *
2314 dbuf_hold_level(dnode_t *dn, int level, uint64_t blkid, void *tag)
2315 {
2316 dmu_buf_impl_t *db;
2317 int err = dbuf_hold_impl(dn, level, blkid, FALSE, FALSE, tag, &db);
2318 return (err ? NULL : db);
2319 }
2320
2321 void
2322 dbuf_create_bonus(dnode_t *dn)
2323 {
2324 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
2325
2326 ASSERT(dn->dn_bonus == NULL);
2327 dn->dn_bonus = dbuf_create(dn, 0, DMU_BONUS_BLKID, dn->dn_dbuf, NULL);
2328 }
2329
2330 int
2331 dbuf_spill_set_blksz(dmu_buf_t *db_fake, uint64_t blksz, dmu_tx_t *tx)
2332 {
2333 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2334 dnode_t *dn;
2335
2336 if (db->db_blkid != DMU_SPILL_BLKID)
2337 return (SET_ERROR(ENOTSUP));
2338 if (blksz == 0)
2339 blksz = SPA_MINBLOCKSIZE;
2340 ASSERT3U(blksz, <=, spa_maxblocksize(dmu_objset_spa(db->db_objset)));
2341 blksz = P2ROUNDUP(blksz, SPA_MINBLOCKSIZE);
2342
2343 DB_DNODE_ENTER(db);
2344 dn = DB_DNODE(db);
2345 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
2346 dbuf_new_size(db, blksz, tx);
2347 rw_exit(&dn->dn_struct_rwlock);
2348 DB_DNODE_EXIT(db);
2349
2350 return (0);
2351 }
2352
2353 void
2354 dbuf_rm_spill(dnode_t *dn, dmu_tx_t *tx)
2355 {
2356 dbuf_free_range(dn, DMU_SPILL_BLKID, DMU_SPILL_BLKID, tx);
2357 }
2358
2359 #pragma weak dmu_buf_add_ref = dbuf_add_ref
2360 void
2361 dbuf_add_ref(dmu_buf_impl_t *db, void *tag)
2362 {
2363 int64_t holds = refcount_add(&db->db_holds, tag);
2364 ASSERT(holds > 1);
2365 }
2366
2367 #pragma weak dmu_buf_try_add_ref = dbuf_try_add_ref
2368 boolean_t
2369 dbuf_try_add_ref(dmu_buf_t *db_fake, objset_t *os, uint64_t obj, uint64_t blkid,
2370 void *tag)
2371 {
2372 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2373 dmu_buf_impl_t *found_db;
2374 boolean_t result = B_FALSE;
2375
2376 if (db->db_blkid == DMU_BONUS_BLKID)
2377 found_db = dbuf_find_bonus(os, obj);
2378 else
2379 found_db = dbuf_find(os, obj, 0, blkid);
2380
2381 if (found_db != NULL) {
2382 if (db == found_db && dbuf_refcount(db) > db->db_dirtycnt) {
2383 (void) refcount_add(&db->db_holds, tag);
2384 result = B_TRUE;
2385 }
2386 mutex_exit(&db->db_mtx);
2387 }
2388 return (result);
2389 }
2390
2391 /*
2392 * If you call dbuf_rele() you had better not be referencing the dnode handle
2393 * unless you have some other direct or indirect hold on the dnode. (An indirect
2394 * hold is a hold on one of the dnode's dbufs, including the bonus buffer.)
2395 * Without that, the dbuf_rele() could lead to a dnode_rele() followed by the
2396 * dnode's parent dbuf evicting its dnode handles.
2397 */
2398 void
2399 dbuf_rele(dmu_buf_impl_t *db, void *tag)
2400 {
2401 mutex_enter(&db->db_mtx);
2402 dbuf_rele_and_unlock(db, tag);
2403 }
2404
2405 void
2406 dmu_buf_rele(dmu_buf_t *db, void *tag)
2407 {
2408 dbuf_rele((dmu_buf_impl_t *)db, tag);
2409 }
2410
2411 /*
2412 * dbuf_rele() for an already-locked dbuf. This is necessary to allow
2413 * db_dirtycnt and db_holds to be updated atomically.
2414 */
2415 void
2416 dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag)
2417 {
2418 int64_t holds;
2419
2420 ASSERT(MUTEX_HELD(&db->db_mtx));
2421 DBUF_VERIFY(db);
2422
2423 /*
2424 * Remove the reference to the dbuf before removing its hold on the
2425 * dnode so we can guarantee in dnode_move() that a referenced bonus
2426 * buffer has a corresponding dnode hold.
2427 */
2428 holds = refcount_remove(&db->db_holds, tag);
2429 ASSERT(holds >= 0);
2430
2431 /*
2432 * We can't freeze indirects if there is a possibility that they
2433 * may be modified in the current syncing context.
2434 */
2435 if (db->db_buf && holds == (db->db_level == 0 ? db->db_dirtycnt : 0))
2436 arc_buf_freeze(db->db_buf);
2437
2438 if (holds == db->db_dirtycnt &&
2439 db->db_level == 0 && db->db_user_immediate_evict)
2440 dbuf_evict_user(db);
2441
2442 if (holds == 0) {
2443 if (db->db_blkid == DMU_BONUS_BLKID) {
2444 dnode_t *dn;
2445 boolean_t evict_dbuf = db->db_pending_evict;
2446
2447 /*
2448 * If the dnode moves here, we cannot cross this
2449 * barrier until the move completes.
2450 */
2451 DB_DNODE_ENTER(db);
2452
2453 dn = DB_DNODE(db);
2454 atomic_dec_32(&dn->dn_dbufs_count);
2455
2456 /*
2457 * Decrementing the dbuf count means that the bonus
2458 * buffer's dnode hold is no longer discounted in
2459 * dnode_move(). The dnode cannot move until after
2460 * the dnode_rele() below.
2461 */
2462 DB_DNODE_EXIT(db);
2463
2464 /*
2465 * Do not reference db after its lock is dropped.
2466 * Another thread may evict it.
2467 */
2468 mutex_exit(&db->db_mtx);
2469
2470 if (evict_dbuf)
2471 dnode_evict_bonus(dn);
2472
2473 dnode_rele(dn, db);
2474 } else if (db->db_buf == NULL) {
2475 /*
2476 * This is a special case: we never associated this
2477 * dbuf with any data allocated from the ARC.
2478 */
2479 ASSERT(db->db_state == DB_UNCACHED ||
2480 db->db_state == DB_NOFILL);
2481 dbuf_evict(db);
2482 } else if (arc_released(db->db_buf)) {
2483 arc_buf_t *buf = db->db_buf;
2484 /*
2485 * This dbuf has anonymous data associated with it.
2486 */
2487 dbuf_clear_data(db);
2488 VERIFY(arc_buf_remove_ref(buf, db));
2489 dbuf_evict(db);
2490 } else {
2491 VERIFY(!arc_buf_remove_ref(db->db_buf, db));
2492
2493 /*
2494 * A dbuf will be eligible for eviction if either the
2495 * 'primarycache' property is set or a duplicate
2496 * copy of this buffer is already cached in the arc.
2497 *
2498 * In the case of the 'primarycache' a buffer
2499 * is considered for eviction if it matches the
2500 * criteria set in the property.
2501 *
2502 * To decide if our buffer is considered a
2503 * duplicate, we must call into the arc to determine
2504 * if multiple buffers are referencing the same
2505 * block on-disk. If so, then we simply evict
2506 * ourselves.
2507 */
2508 if (!DBUF_IS_CACHEABLE(db)) {
2509 if (db->db_blkptr != NULL &&
2510 !BP_IS_HOLE(db->db_blkptr) &&
2511 !BP_IS_EMBEDDED(db->db_blkptr)) {
2512 spa_t *spa =
2513 dmu_objset_spa(db->db_objset);
2514 blkptr_t bp = *db->db_blkptr;
2515 dbuf_clear(db);
2516 arc_freed(spa, &bp);
2517 } else {
2518 dbuf_clear(db);
2519 }
2520 } else if (db->db_pending_evict ||
2521 arc_buf_eviction_needed(db->db_buf)) {
2522 dbuf_clear(db);
2523 } else {
2524 mutex_exit(&db->db_mtx);
2525 }
2526 }
2527 } else {
2528 mutex_exit(&db->db_mtx);
2529 }
2530 }
2531
2532 #pragma weak dmu_buf_refcount = dbuf_refcount
2533 uint64_t
2534 dbuf_refcount(dmu_buf_impl_t *db)
2535 {
2536 return (refcount_count(&db->db_holds));
2537 }
2538
2539 void *
2540 dmu_buf_replace_user(dmu_buf_t *db_fake, dmu_buf_user_t *old_user,
2541 dmu_buf_user_t *new_user)
2542 {
2543 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2544
2545 mutex_enter(&db->db_mtx);
2546 dbuf_verify_user(db, DBVU_NOT_EVICTING);
2547 if (db->db_user == old_user)
2548 db->db_user = new_user;
2549 else
2550 old_user = db->db_user;
2551 dbuf_verify_user(db, DBVU_NOT_EVICTING);
2552 mutex_exit(&db->db_mtx);
2553
2554 return (old_user);
2555 }
2556
2557 void *
2558 dmu_buf_set_user(dmu_buf_t *db_fake, dmu_buf_user_t *user)
2559 {
2560 return (dmu_buf_replace_user(db_fake, NULL, user));
2561 }
2562
2563 void *
2564 dmu_buf_set_user_ie(dmu_buf_t *db_fake, dmu_buf_user_t *user)
2565 {
2566 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2567
2568 db->db_user_immediate_evict = TRUE;
2569 return (dmu_buf_set_user(db_fake, user));
2570 }
2571
2572 void *
2573 dmu_buf_remove_user(dmu_buf_t *db_fake, dmu_buf_user_t *user)
2574 {
2575 return (dmu_buf_replace_user(db_fake, user, NULL));
2576 }
2577
2578 void *
2579 dmu_buf_get_user(dmu_buf_t *db_fake)
2580 {
2581 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2582
2583 dbuf_verify_user(db, DBVU_NOT_EVICTING);
2584 return (db->db_user);
2585 }
2586
2587 void
2588 dmu_buf_user_evict_wait()
2589 {
2590 taskq_wait(dbu_evict_taskq);
2591 }
2592
2593 boolean_t
2594 dmu_buf_freeable(dmu_buf_t *dbuf)
2595 {
2596 boolean_t res = B_FALSE;
2597 dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf;
2598
2599 if (db->db_blkptr)
2600 res = dsl_dataset_block_freeable(db->db_objset->os_dsl_dataset,
2601 db->db_blkptr, db->db_blkptr->blk_birth);
2602
2603 return (res);
2604 }
2605
2606 blkptr_t *
2607 dmu_buf_get_blkptr(dmu_buf_t *db)
2608 {
2609 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
2610 return (dbi->db_blkptr);
2611 }
2612
2613 static void
2614 dbuf_check_blkptr(dnode_t *dn, dmu_buf_impl_t *db)
2615 {
2616 /* ASSERT(dmu_tx_is_syncing(tx) */
2617 ASSERT(MUTEX_HELD(&db->db_mtx));
2618
2619 if (db->db_blkptr != NULL)
2620 return;
2621
2622 if (db->db_blkid == DMU_SPILL_BLKID) {
2623 db->db_blkptr = &dn->dn_phys->dn_spill;
2624 BP_ZERO(db->db_blkptr);
2625 return;
2626 }
2627 if (db->db_level == dn->dn_phys->dn_nlevels-1) {
2628 /*
2629 * This buffer was allocated at a time when there was
2630 * no available blkptrs from the dnode, or it was
2631 * inappropriate to hook it in (i.e., nlevels mis-match).
2632 */
2633 ASSERT(db->db_blkid < dn->dn_phys->dn_nblkptr);
2634 ASSERT(db->db_parent == NULL);
2635 db->db_parent = dn->dn_dbuf;
2636 db->db_blkptr = &dn->dn_phys->dn_blkptr[db->db_blkid];
2637 DBUF_VERIFY(db);
2638 } else {
2639 dmu_buf_impl_t *parent = db->db_parent;
2640 int epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2641
2642 ASSERT(dn->dn_phys->dn_nlevels > 1);
2643 if (parent == NULL) {
2644 mutex_exit(&db->db_mtx);
2645 rw_enter(&dn->dn_struct_rwlock, RW_READER);
2646 parent = dbuf_hold_level(dn, db->db_level + 1,
2647 db->db_blkid >> epbs, db);
2648 rw_exit(&dn->dn_struct_rwlock);
2649 mutex_enter(&db->db_mtx);
2650 db->db_parent = parent;
2651 }
2652 db->db_blkptr = (blkptr_t *)parent->db.db_data +
2653 (db->db_blkid & ((1ULL << epbs) - 1));
2654 DBUF_VERIFY(db);
2655 }
2656 }
2657
2658 static void
2659 dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
2660 {
2661 dmu_buf_impl_t *db = dr->dr_dbuf;
2662 dnode_t *dn;
2663 zio_t *zio;
2664
2665 ASSERT(dmu_tx_is_syncing(tx));
2666
2667 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
2668
2669 mutex_enter(&db->db_mtx);
2670
2671 ASSERT(db->db_level > 0);
2672 DBUF_VERIFY(db);
2673
2674 /* Read the block if it hasn't been read yet. */
2675 if (db->db_buf == NULL) {
2676 mutex_exit(&db->db_mtx);
2677 (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED);
2678 mutex_enter(&db->db_mtx);
2679 }
2680 ASSERT3U(db->db_state, ==, DB_CACHED);
2681 ASSERT(db->db_buf != NULL);
2682
2683 DB_DNODE_ENTER(db);
2684 dn = DB_DNODE(db);
2685 /* Indirect block size must match what the dnode thinks it is. */
2686 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2687 dbuf_check_blkptr(dn, db);
2688 DB_DNODE_EXIT(db);
2689
2690 /* Provide the pending dirty record to child dbufs */
2691 db->db_data_pending = dr;
2692
2693 mutex_exit(&db->db_mtx);
2694 dbuf_write(dr, db->db_buf, tx);
2695
2696 zio = dr->dr_zio;
2697 mutex_enter(&dr->dt.di.dr_mtx);
2698 dbuf_sync_list(&dr->dt.di.dr_children, db->db_level - 1, tx);
2699 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
2700 mutex_exit(&dr->dt.di.dr_mtx);
2701 zio_nowait(zio);
2702 }
2703
2704 static void
2705 dbuf_sync_leaf(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
2706 {
2707 arc_buf_t **datap = &dr->dt.dl.dr_data;
2708 dmu_buf_impl_t *db = dr->dr_dbuf;
2709 dnode_t *dn;
2710 objset_t *os;
2711 uint64_t txg = tx->tx_txg;
2712
2713 ASSERT(dmu_tx_is_syncing(tx));
2714
2715 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
2716
2717 mutex_enter(&db->db_mtx);
2718 /*
2719 * To be synced, we must be dirtied. But we
2720 * might have been freed after the dirty.
2721 */
2722 if (db->db_state == DB_UNCACHED) {
2723 /* This buffer has been freed since it was dirtied */
2724 ASSERT(db->db.db_data == NULL);
2725 } else if (db->db_state == DB_FILL) {
2726 /* This buffer was freed and is now being re-filled */
2727 ASSERT(db->db.db_data != dr->dt.dl.dr_data);
2728 } else {
2729 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_NOFILL);
2730 }
2731 DBUF_VERIFY(db);
2732
2733 DB_DNODE_ENTER(db);
2734 dn = DB_DNODE(db);
2735
2736 if (db->db_blkid == DMU_SPILL_BLKID) {
2737 mutex_enter(&dn->dn_mtx);
2738 dn->dn_phys->dn_flags |= DNODE_FLAG_SPILL_BLKPTR;
2739 mutex_exit(&dn->dn_mtx);
2740 }
2741
2742 /*
2743 * If this is a bonus buffer, simply copy the bonus data into the
2744 * dnode. It will be written out when the dnode is synced (and it
2745 * will be synced, since it must have been dirty for dbuf_sync to
2746 * be called).
2747 */
2748 if (db->db_blkid == DMU_BONUS_BLKID) {
2749 dbuf_dirty_record_t **drp;
2750
2751 ASSERT(*datap != NULL);
2752 ASSERT0(db->db_level);
2753 ASSERT3U(dn->dn_phys->dn_bonuslen, <=, DN_MAX_BONUSLEN);
2754 bcopy(*datap, DN_BONUS(dn->dn_phys), dn->dn_phys->dn_bonuslen);
2755 DB_DNODE_EXIT(db);
2756
2757 if (*datap != db->db.db_data) {
2758 zio_buf_free(*datap, DN_MAX_BONUSLEN);
2759 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
2760 }
2761 db->db_data_pending = NULL;
2762 drp = &db->db_last_dirty;
2763 while (*drp != dr)
2764 drp = &(*drp)->dr_next;
2765 ASSERT(dr->dr_next == NULL);
2766 ASSERT(dr->dr_dbuf == db);
2767 *drp = dr->dr_next;
2768 kmem_free(dr, sizeof (dbuf_dirty_record_t));
2769 ASSERT(db->db_dirtycnt > 0);
2770 db->db_dirtycnt -= 1;
2771 dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg);
2772 return;
2773 }
2774
2775 os = dn->dn_objset;
2776
2777 /*
2778 * This function may have dropped the db_mtx lock allowing a dmu_sync
2779 * operation to sneak in. As a result, we need to ensure that we
2780 * don't check the dr_override_state until we have returned from
2781 * dbuf_check_blkptr.
2782 */
2783 dbuf_check_blkptr(dn, db);
2784
2785 /*
2786 * If this buffer is in the middle of an immediate write,
2787 * wait for the synchronous IO to complete.
2788 */
2789 while (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC) {
2790 ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
2791 cv_wait(&db->db_changed, &db->db_mtx);
2792 ASSERT(dr->dt.dl.dr_override_state != DR_NOT_OVERRIDDEN);
2793 }
2794
2795 if (db->db_state != DB_NOFILL &&
2796 dn->dn_object != DMU_META_DNODE_OBJECT &&
2797 refcount_count(&db->db_holds) > 1 &&
2798 dr->dt.dl.dr_override_state != DR_OVERRIDDEN &&
2799 *datap == db->db_buf) {
2800 /*
2801 * If this buffer is currently "in use" (i.e., there
2802 * are active holds and db_data still references it),
2803 * then make a copy before we start the write so that
2804 * any modifications from the open txg will not leak
2805 * into this write.
2806 *
2807 * NOTE: this copy does not need to be made for
2808 * objects only modified in the syncing context (e.g.
2809 * DNONE_DNODE blocks).
2810 */
2811 int blksz = arc_buf_size(*datap);
2812 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
2813 *datap = arc_buf_alloc(os->os_spa, blksz, db, type);
2814 bcopy(db->db.db_data, (*datap)->b_data, blksz);
2815 }
2816 db->db_data_pending = dr;
2817
2818 mutex_exit(&db->db_mtx);
2819
2820 dbuf_write(dr, *datap, tx);
2821
2822 ASSERT(!list_link_active(&dr->dr_dirty_node));
2823 if (dn->dn_object == DMU_META_DNODE_OBJECT) {
2824 list_insert_tail(&dn->dn_dirty_records[txg&TXG_MASK], dr);
2825 DB_DNODE_EXIT(db);
2826 } else {
2827 /*
2828 * Although zio_nowait() does not "wait for an IO", it does
2829 * initiate the IO. If this is an empty write it seems plausible
2830 * that the IO could actually be completed before the nowait
2831 * returns. We need to DB_DNODE_EXIT() first in case
2832 * zio_nowait() invalidates the dbuf.
2833 */
2834 DB_DNODE_EXIT(db);
2835 zio_nowait(dr->dr_zio);
2836 }
2837 }
2838
2839 void
2840 dbuf_sync_list(list_t *list, int level, dmu_tx_t *tx)
2841 {
2842 dbuf_dirty_record_t *dr;
2843
2844 while (dr = list_head(list)) {
2845 if (dr->dr_zio != NULL) {
2846 /*
2847 * If we find an already initialized zio then we
2848 * are processing the meta-dnode, and we have finished.
2849 * The dbufs for all dnodes are put back on the list
2850 * during processing, so that we can zio_wait()
2851 * these IOs after initiating all child IOs.
2852 */
2853 ASSERT3U(dr->dr_dbuf->db.db_object, ==,
2854 DMU_META_DNODE_OBJECT);
2855 break;
2856 }
2857 if (dr->dr_dbuf->db_blkid != DMU_BONUS_BLKID &&
2858 dr->dr_dbuf->db_blkid != DMU_SPILL_BLKID) {
2859 VERIFY3U(dr->dr_dbuf->db_level, ==, level);
2860 }
2861 list_remove(list, dr);
2862 if (dr->dr_dbuf->db_level > 0)
2863 dbuf_sync_indirect(dr, tx);
2864 else
2865 dbuf_sync_leaf(dr, tx);
2866 }
2867 }
2868
2869 /* ARGSUSED */
2870 static void
2871 dbuf_write_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
2872 {
2873 dmu_buf_impl_t *db = vdb;
2874 dnode_t *dn;
2875 blkptr_t *bp = zio->io_bp;
2876 blkptr_t *bp_orig = &zio->io_bp_orig;
2877 spa_t *spa = zio->io_spa;
2878 int64_t delta;
2879 uint64_t fill = 0;
2880 int i;
2881
2882 ASSERT3P(db->db_blkptr, ==, bp);
2883
2884 DB_DNODE_ENTER(db);
2885 dn = DB_DNODE(db);
2886 delta = bp_get_dsize_sync(spa, bp) - bp_get_dsize_sync(spa, bp_orig);
2887 dnode_diduse_space(dn, delta - zio->io_prev_space_delta);
2888 zio->io_prev_space_delta = delta;
2889
2890 if (bp->blk_birth != 0) {
2891 ASSERT((db->db_blkid != DMU_SPILL_BLKID &&
2892 BP_GET_TYPE(bp) == dn->dn_type) ||
2893 (db->db_blkid == DMU_SPILL_BLKID &&
2894 BP_GET_TYPE(bp) == dn->dn_bonustype) ||
2895 BP_IS_EMBEDDED(bp));
2896 ASSERT(BP_GET_LEVEL(bp) == db->db_level);
2897 }
2898
2899 mutex_enter(&db->db_mtx);
2900
2901 #ifdef ZFS_DEBUG
2902 if (db->db_blkid == DMU_SPILL_BLKID) {
2903 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
2904 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
2905 db->db_blkptr == &dn->dn_phys->dn_spill);
2906 }
2907 #endif
2908
2909 if (db->db_level == 0) {
2910 mutex_enter(&dn->dn_mtx);
2911 if (db->db_blkid > dn->dn_phys->dn_maxblkid &&
2912 db->db_blkid != DMU_SPILL_BLKID)
2913 dn->dn_phys->dn_maxblkid = db->db_blkid;
2914 mutex_exit(&dn->dn_mtx);
2915
2916 if (dn->dn_type == DMU_OT_DNODE) {
2917 dnode_phys_t *dnp = db->db.db_data;
2918 for (i = db->db.db_size >> DNODE_SHIFT; i > 0;
2919 i--, dnp++) {
2920 if (dnp->dn_type != DMU_OT_NONE)
2921 fill++;
2922 }
2923 } else {
2924 if (BP_IS_HOLE(bp)) {
2925 fill = 0;
2926 } else {
2927 fill = 1;
2928 }
2929 }
2930 } else {
2931 blkptr_t *ibp = db->db.db_data;
2932 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2933 for (i = db->db.db_size >> SPA_BLKPTRSHIFT; i > 0; i--, ibp++) {
2934 if (BP_IS_HOLE(ibp))
2935 continue;
2936 fill += BP_GET_FILL(ibp);
2937 }
2938 }
2939 DB_DNODE_EXIT(db);
2940
2941 if (!BP_IS_EMBEDDED(bp))
2942 bp->blk_fill = fill;
2943
2944 mutex_exit(&db->db_mtx);
2945 }
2946
2947 /*
2948 * The SPA will call this callback several times for each zio - once
2949 * for every physical child i/o (zio->io_phys_children times). This
2950 * allows the DMU to monitor the progress of each logical i/o. For example,
2951 * there may be 2 copies of an indirect block, or many fragments of a RAID-Z
2952 * block. There may be a long delay before all copies/fragments are completed,
2953 * so this callback allows us to retire dirty space gradually, as the physical
2954 * i/os complete.
2955 */
2956 /* ARGSUSED */
2957 static void
2958 dbuf_write_physdone(zio_t *zio, arc_buf_t *buf, void *arg)
2959 {
2960 dmu_buf_impl_t *db = arg;
2961 objset_t *os = db->db_objset;
2962 dsl_pool_t *dp = dmu_objset_pool(os);
2963 dbuf_dirty_record_t *dr;
2964 int delta = 0;
2965
2966 dr = db->db_data_pending;
2967 ASSERT3U(dr->dr_txg, ==, zio->io_txg);
2968
2969 /*
2970 * The callback will be called io_phys_children times. Retire one
2971 * portion of our dirty space each time we are called. Any rounding
2972 * error will be cleaned up by dsl_pool_sync()'s call to
2973 * dsl_pool_undirty_space().
2974 */
2975 delta = dr->dr_accounted / zio->io_phys_children;
2976 dsl_pool_undirty_space(dp, delta, zio->io_txg);
2977 }
2978
2979 /* ARGSUSED */
2980 static void
2981 dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb)
2982 {
2983 dmu_buf_impl_t *db = vdb;
2984 blkptr_t *bp_orig = &zio->io_bp_orig;
2985 blkptr_t *bp = db->db_blkptr;
2986 objset_t *os = db->db_objset;
2987 dmu_tx_t *tx = os->os_synctx;
2988 dbuf_dirty_record_t **drp, *dr;
2989
2990 ASSERT0(zio->io_error);
2991 ASSERT(db->db_blkptr == bp);
2992
2993 /*
2994 * For nopwrites and rewrites we ensure that the bp matches our
2995 * original and bypass all the accounting.
2996 */
2997 if (zio->io_flags & (ZIO_FLAG_IO_REWRITE | ZIO_FLAG_NOPWRITE)) {
2998 ASSERT(BP_EQUAL(bp, bp_orig));
2999 } else {
3000 dsl_dataset_t *ds = os->os_dsl_dataset;
3001 (void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE);
3002 dsl_dataset_block_born(ds, bp, tx);
3003 }
3004
3005 mutex_enter(&db->db_mtx);
3006
3007 DBUF_VERIFY(db);
3008
3009 drp = &db->db_last_dirty;
3010 while ((dr = *drp) != db->db_data_pending)
3011 drp = &dr->dr_next;
3012 ASSERT(!list_link_active(&dr->dr_dirty_node));
3013 ASSERT(dr->dr_dbuf == db);
3014 ASSERT(dr->dr_next == NULL);
3015 *drp = dr->dr_next;
3016
3017 #ifdef ZFS_DEBUG
3018 if (db->db_blkid == DMU_SPILL_BLKID) {
3019 dnode_t *dn;
3020
3021 DB_DNODE_ENTER(db);
3022 dn = DB_DNODE(db);
3023 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
3024 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
3025 db->db_blkptr == &dn->dn_phys->dn_spill);
3026 DB_DNODE_EXIT(db);
3027 }
3028 #endif
3029
3030 if (db->db_level == 0) {
3031 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
3032 ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
3033 if (db->db_state != DB_NOFILL) {
3034 if (dr->dt.dl.dr_data != db->db_buf)
3035 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data,
3036 db));
3037 else if (!arc_released(db->db_buf))
3038 arc_set_callback(db->db_buf, dbuf_do_evict, db);
3039 }
3040 } else {
3041 dnode_t *dn;
3042
3043 DB_DNODE_ENTER(db);
3044 dn = DB_DNODE(db);
3045 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
3046 ASSERT3U(db->db.db_size, ==, 1 << dn->dn_phys->dn_indblkshift);
3047 if (!BP_IS_HOLE(db->db_blkptr)) {
3048 int epbs =
3049 dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
3050 ASSERT3U(db->db_blkid, <=,
3051 dn->dn_phys->dn_maxblkid >> (db->db_level * epbs));
3052 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==,
3053 db->db.db_size);
3054 if (!arc_released(db->db_buf))
3055 arc_set_callback(db->db_buf, dbuf_do_evict, db);
3056 }
3057 DB_DNODE_EXIT(db);
3058 mutex_destroy(&dr->dt.di.dr_mtx);
3059 list_destroy(&dr->dt.di.dr_children);
3060 }
3061 kmem_free(dr, sizeof (dbuf_dirty_record_t));
3062
3063 cv_broadcast(&db->db_changed);
3064 ASSERT(db->db_dirtycnt > 0);
3065 db->db_dirtycnt -= 1;
3066 db->db_data_pending = NULL;
3067 dbuf_rele_and_unlock(db, (void *)(uintptr_t)tx->tx_txg);
3068 }
3069
3070 static void
3071 dbuf_write_nofill_ready(zio_t *zio)
3072 {
3073 dbuf_write_ready(zio, NULL, zio->io_private);
3074 }
3075
3076 static void
3077 dbuf_write_nofill_done(zio_t *zio)
3078 {
3079 dbuf_write_done(zio, NULL, zio->io_private);
3080 }
3081
3082 static void
3083 dbuf_write_override_ready(zio_t *zio)
3084 {
3085 dbuf_dirty_record_t *dr = zio->io_private;
3086 dmu_buf_impl_t *db = dr->dr_dbuf;
3087
3088 dbuf_write_ready(zio, NULL, db);
3089 }
3090
3091 static void
3092 dbuf_write_override_done(zio_t *zio)
3093 {
3094 dbuf_dirty_record_t *dr = zio->io_private;
3095 dmu_buf_impl_t *db = dr->dr_dbuf;
3096 blkptr_t *obp = &dr->dt.dl.dr_overridden_by;
3097
3098 mutex_enter(&db->db_mtx);
3099 if (!BP_EQUAL(zio->io_bp, obp)) {
3100 if (!BP_IS_HOLE(obp))
3101 dsl_free(spa_get_dsl(zio->io_spa), zio->io_txg, obp);
3102 arc_release(dr->dt.dl.dr_data, db);
3103 }
3104 mutex_exit(&db->db_mtx);
3105
3106 dbuf_write_done(zio, NULL, db);
3107 }
3108
3109 /* Issue I/O to commit a dirty buffer to disk. */
3110 static void
3111 dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx)
3112 {
3113 dmu_buf_impl_t *db = dr->dr_dbuf;
3114 dnode_t *dn;
3115 objset_t *os;
3116 dmu_buf_impl_t *parent = db->db_parent;
3117 uint64_t txg = tx->tx_txg;
3118 zbookmark_phys_t zb;
3119 zio_prop_t zp;
3120 zio_t *zio;
3121 int wp_flag = 0;
3122
3123 DB_DNODE_ENTER(db);
3124 dn = DB_DNODE(db);
3125 os = dn->dn_objset;
3126
3127 if (db->db_state != DB_NOFILL) {
3128 if (db->db_level > 0 || dn->dn_type == DMU_OT_DNODE) {
3129 /*
3130 * Private object buffers are released here rather
3131 * than in dbuf_dirty() since they are only modified
3132 * in the syncing context and we don't want the
3133 * overhead of making multiple copies of the data.
3134 */
3135 if (BP_IS_HOLE(db->db_blkptr)) {
3136 arc_buf_thaw(data);
3137 } else {
3138 dbuf_release_bp(db);
3139 }
3140 }
3141 }
3142
3143 if (parent != dn->dn_dbuf) {
3144 /* Our parent is an indirect block. */
3145 /* We have a dirty parent that has been scheduled for write. */
3146 ASSERT(parent && parent->db_data_pending);
3147 /* Our parent's buffer is one level closer to the dnode. */
3148 ASSERT(db->db_level == parent->db_level-1);
3149 /*
3150 * We're about to modify our parent's db_data by modifying
3151 * our block pointer, so the parent must be released.
3152 */
3153 ASSERT(arc_released(parent->db_buf));
3154 zio = parent->db_data_pending->dr_zio;
3155 } else {
3156 /* Our parent is the dnode itself. */
3157 ASSERT((db->db_level == dn->dn_phys->dn_nlevels-1 &&
3158 db->db_blkid != DMU_SPILL_BLKID) ||
3159 (db->db_blkid == DMU_SPILL_BLKID && db->db_level == 0));
3160 if (db->db_blkid != DMU_SPILL_BLKID)
3161 ASSERT3P(db->db_blkptr, ==,
3162 &dn->dn_phys->dn_blkptr[db->db_blkid]);
3163 zio = dn->dn_zio;
3164 }
3165
3166 ASSERT(db->db_level == 0 || data == db->db_buf);
3167 ASSERT3U(db->db_blkptr->blk_birth, <=, txg);
3168 ASSERT(zio);
3169
3170 SET_BOOKMARK(&zb, os->os_dsl_dataset ?
3171 os->os_dsl_dataset->ds_object : DMU_META_OBJSET,
3172 db->db.db_object, db->db_level, db->db_blkid);
3173
3174 if (db->db_blkid == DMU_SPILL_BLKID)
3175 wp_flag = WP_SPILL;
3176 wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0;
3177
3178 dmu_write_policy(os, dn, db->db_level, wp_flag, &zp);
3179 DB_DNODE_EXIT(db);
3180
3181 if (db->db_level == 0 &&
3182 dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
3183 /*
3184 * The BP for this block has been provided by open context
3185 * (by dmu_sync() or dmu_buf_write_embedded()).
3186 */
3187 void *contents = (data != NULL) ? data->b_data : NULL;
3188
3189 dr->dr_zio = zio_write(zio, os->os_spa, txg,
3190 db->db_blkptr, contents, db->db.db_size, &zp,
3191 dbuf_write_override_ready, NULL, dbuf_write_override_done,
3192 dr, ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
3193 mutex_enter(&db->db_mtx);
3194 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
3195 zio_write_override(dr->dr_zio, &dr->dt.dl.dr_overridden_by,
3196 dr->dt.dl.dr_copies, dr->dt.dl.dr_nopwrite);
3197 mutex_exit(&db->db_mtx);
3198 } else if (db->db_state == DB_NOFILL) {
3199 ASSERT(zp.zp_checksum == ZIO_CHECKSUM_OFF ||
3200 zp.zp_checksum == ZIO_CHECKSUM_NOPARITY);
3201 dr->dr_zio = zio_write(zio, os->os_spa, txg,
3202 db->db_blkptr, NULL, db->db.db_size, &zp,
3203 dbuf_write_nofill_ready, NULL, dbuf_write_nofill_done, db,
3204 ZIO_PRIORITY_ASYNC_WRITE,
3205 ZIO_FLAG_MUSTSUCCEED | ZIO_FLAG_NODATA, &zb);
3206 } else {
3207 ASSERT(arc_released(data));
3208 dr->dr_zio = arc_write(zio, os->os_spa, txg,
3209 db->db_blkptr, data, DBUF_IS_L2CACHEABLE(db),
3210 DBUF_IS_L2COMPRESSIBLE(db), &zp, dbuf_write_ready,
3211 dbuf_write_physdone, dbuf_write_done, db,
3212 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
3213 }
3214 }