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
912 if (end_blkid > dn->dn_maxblkid && (end_blkid != DMU_SPILL_BLKID))
913 end_blkid = dn->dn_maxblkid;
914 dprintf_dnode(dn, "start=%llu end=%llu\n", start_blkid, end_blkid);
915
916 db_search.db_level = 0;
917 db_search.db_blkid = start_blkid;
918 db_search.db_state = DB_SEARCH;
919
920 mutex_enter(&dn->dn_dbufs_mtx);
921 if (start_blkid >= dn->dn_unlisted_l0_blkid) {
922 /* There can't be any dbufs in this range; no need to search. */
923 #ifdef DEBUG
924 db = avl_find(&dn->dn_dbufs, &db_search, &where);
925 ASSERT3P(db, ==, NULL);
926 db = avl_nearest(&dn->dn_dbufs, where, AVL_AFTER);
927 ASSERT(db == NULL || db->db_level > 0);
928 #endif
929 mutex_exit(&dn->dn_dbufs_mtx);
930 return;
931 } else if (dmu_objset_is_receiving(dn->dn_objset)) {
932 /*
933 * If we are receiving, we expect there to be no dbufs in
934 * the range to be freed, because receive modifies each
935 * block at most once, and in offset order. If this is
936 * not the case, it can lead to performance problems,
937 * so note that we unexpectedly took the slow path.
938 */
939 atomic_inc_64(&zfs_free_range_recv_miss);
940 }
941
942 db = avl_find(&dn->dn_dbufs, &db_search, &where);
943 ASSERT3P(db, ==, NULL);
944 db = avl_nearest(&dn->dn_dbufs, where, AVL_AFTER);
945
946 for (; db != NULL; db = db_next) {
947 db_next = AVL_NEXT(&dn->dn_dbufs, db);
948 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
949
950 if (db->db_level != 0 || db->db_blkid > end_blkid) {
951 break;
952 }
953 ASSERT3U(db->db_blkid, >=, start_blkid);
954
955 /* found a level 0 buffer in the range */
956 mutex_enter(&db->db_mtx);
957 if (dbuf_undirty(db, tx)) {
958 /* mutex has been dropped and dbuf destroyed */
959 continue;
960 }
961
962 if (db->db_state == DB_UNCACHED ||
963 db->db_state == DB_NOFILL ||
964 db->db_state == DB_EVICTING) {
965 ASSERT(db->db.db_data == NULL);
966 mutex_exit(&db->db_mtx);
967 continue;
968 }
969 if (db->db_state == DB_READ || db->db_state == DB_FILL) {
970 /* will be handled in dbuf_read_done or dbuf_rele */
971 db->db_freed_in_flight = TRUE;
972 mutex_exit(&db->db_mtx);
973 continue;
974 }
975 if (refcount_count(&db->db_holds) == 0) {
976 ASSERT(db->db_buf);
977 dbuf_clear(db);
978 continue;
979 }
980 /* The dbuf is referenced */
981
982 if (db->db_last_dirty != NULL) {
983 dbuf_dirty_record_t *dr = db->db_last_dirty;
984
985 if (dr->dr_txg == txg) {
986 /*
987 * This buffer is "in-use", re-adjust the file
988 * size to reflect that this buffer may
989 * contain new data when we sync.
990 */
991 if (db->db_blkid != DMU_SPILL_BLKID &&
992 db->db_blkid > dn->dn_maxblkid)
993 dn->dn_maxblkid = db->db_blkid;
994 dbuf_unoverride(dr);
995 } else {
996 /*
997 * This dbuf is not dirty in the open context.
998 * Either uncache it (if its not referenced in
999 * the open context) or reset its contents to
1000 * empty.
1001 */
1002 dbuf_fix_old_data(db, txg);
1003 }
1004 }
1005 /* clear the contents if its cached */
1006 if (db->db_state == DB_CACHED) {
1007 ASSERT(db->db.db_data != NULL);
1008 arc_release(db->db_buf, db);
1009 bzero(db->db.db_data, db->db.db_size);
1010 arc_buf_freeze(db->db_buf);
1011 }
1012
1013 mutex_exit(&db->db_mtx);
1014 }
1015 mutex_exit(&dn->dn_dbufs_mtx);
1016 }
1017
1018 static int
1019 dbuf_block_freeable(dmu_buf_impl_t *db)
1020 {
1021 dsl_dataset_t *ds = db->db_objset->os_dsl_dataset;
1022 uint64_t birth_txg = 0;
1023
1024 /*
1025 * We don't need any locking to protect db_blkptr:
1026 * If it's syncing, then db_last_dirty will be set
1027 * so we'll ignore db_blkptr.
1028 *
1029 * This logic ensures that only block births for
1030 * filled blocks are considered.
1031 */
1032 ASSERT(MUTEX_HELD(&db->db_mtx));
1033 if (db->db_last_dirty && (db->db_blkptr == NULL ||
1034 !BP_IS_HOLE(db->db_blkptr))) {
1035 birth_txg = db->db_last_dirty->dr_txg;
1036 } else if (db->db_blkptr != NULL && !BP_IS_HOLE(db->db_blkptr)) {
1037 birth_txg = db->db_blkptr->blk_birth;
1038 }
1039
1040 /*
1041 * If this block don't exist or is in a snapshot, it can't be freed.
1042 * Don't pass the bp to dsl_dataset_block_freeable() since we
1043 * are holding the db_mtx lock and might deadlock if we are
1044 * prefetching a dedup-ed block.
1045 */
1046 if (birth_txg != 0)
1047 return (ds == NULL ||
1048 dsl_dataset_block_freeable(ds, NULL, birth_txg));
1049 else
1050 return (B_FALSE);
1051 }
1052
1053 void
1054 dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx)
1055 {
1056 arc_buf_t *buf, *obuf;
1057 int osize = db->db.db_size;
1058 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
1059 dnode_t *dn;
1060
1061 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1062
1063 DB_DNODE_ENTER(db);
1064 dn = DB_DNODE(db);
1065
1066 /* XXX does *this* func really need the lock? */
1067 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
1068
1069 /*
1070 * This call to dmu_buf_will_dirty() with the dn_struct_rwlock held
1071 * is OK, because there can be no other references to the db
1072 * when we are changing its size, so no concurrent DB_FILL can
1073 * be happening.
1074 */
1075 /*
1076 * XXX we should be doing a dbuf_read, checking the return
1077 * value and returning that up to our callers
1078 */
1079 dmu_buf_will_dirty(&db->db, tx);
1080
1081 /* create the data buffer for the new block */
1082 buf = arc_buf_alloc(dn->dn_objset->os_spa, size, db, type);
1083
1084 /* copy old block data to the new block */
1085 obuf = db->db_buf;
1086 bcopy(obuf->b_data, buf->b_data, MIN(osize, size));
1087 /* zero the remainder */
1088 if (size > osize)
1089 bzero((uint8_t *)buf->b_data + osize, size - osize);
1090
1091 mutex_enter(&db->db_mtx);
1092 dbuf_set_data(db, buf);
1093 VERIFY(arc_buf_remove_ref(obuf, db));
1094 db->db.db_size = size;
1095
1096 if (db->db_level == 0) {
1097 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
1098 db->db_last_dirty->dt.dl.dr_data = buf;
1099 }
1100 mutex_exit(&db->db_mtx);
1101
1102 dnode_willuse_space(dn, size-osize, tx);
1103 DB_DNODE_EXIT(db);
1104 }
1105
1106 void
1107 dbuf_release_bp(dmu_buf_impl_t *db)
1108 {
1109 objset_t *os = db->db_objset;
1110
1111 ASSERT(dsl_pool_sync_context(dmu_objset_pool(os)));
1112 ASSERT(arc_released(os->os_phys_buf) ||
1113 list_link_active(&os->os_dsl_dataset->ds_synced_link));
1114 ASSERT(db->db_parent == NULL || arc_released(db->db_parent->db_buf));
1115
1116 (void) arc_release(db->db_buf, db);
1117 }
1118
1119 /*
1120 * We already have a dirty record for this TXG, and we are being
1121 * dirtied again.
1122 */
1123 static void
1124 dbuf_redirty(dbuf_dirty_record_t *dr)
1125 {
1126 dmu_buf_impl_t *db = dr->dr_dbuf;
1127
1128 ASSERT(MUTEX_HELD(&db->db_mtx));
1129
1130 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID) {
1131 /*
1132 * If this buffer has already been written out,
1133 * we now need to reset its state.
1134 */
1135 dbuf_unoverride(dr);
1136 if (db->db.db_object != DMU_META_DNODE_OBJECT &&
1137 db->db_state != DB_NOFILL) {
1138 /* Already released on initial dirty, so just thaw. */
1139 ASSERT(arc_released(db->db_buf));
1140 arc_buf_thaw(db->db_buf);
1141 }
1142 }
1143 }
1144
1145 dbuf_dirty_record_t *
1146 dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1147 {
1148 dnode_t *dn;
1149 objset_t *os;
1150 dbuf_dirty_record_t **drp, *dr;
1151 int drop_struct_lock = FALSE;
1152 boolean_t do_free_accounting = B_FALSE;
1153 int txgoff = tx->tx_txg & TXG_MASK;
1154
1155 ASSERT(tx->tx_txg != 0);
1156 ASSERT(!refcount_is_zero(&db->db_holds));
1157 DMU_TX_DIRTY_BUF(tx, db);
1158
1159 DB_DNODE_ENTER(db);
1160 dn = DB_DNODE(db);
1161 /*
1162 * Shouldn't dirty a regular buffer in syncing context. Private
1163 * objects may be dirtied in syncing context, but only if they
1164 * were already pre-dirtied in open context.
1165 */
1166 ASSERT(!dmu_tx_is_syncing(tx) ||
1167 BP_IS_HOLE(dn->dn_objset->os_rootbp) ||
1168 DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1169 dn->dn_objset->os_dsl_dataset == NULL);
1170 /*
1171 * We make this assert for private objects as well, but after we
1172 * check if we're already dirty. They are allowed to re-dirty
1173 * in syncing context.
1174 */
1175 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1176 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1177 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1178
1179 mutex_enter(&db->db_mtx);
1180 /*
1181 * XXX make this true for indirects too? The problem is that
1182 * transactions created with dmu_tx_create_assigned() from
1183 * syncing context don't bother holding ahead.
1184 */
1185 ASSERT(db->db_level != 0 ||
1186 db->db_state == DB_CACHED || db->db_state == DB_FILL ||
1187 db->db_state == DB_NOFILL);
1188
1189 mutex_enter(&dn->dn_mtx);
1190 /*
1191 * Don't set dirtyctx to SYNC if we're just modifying this as we
1192 * initialize the objset.
1193 */
1194 if (dn->dn_dirtyctx == DN_UNDIRTIED &&
1195 !BP_IS_HOLE(dn->dn_objset->os_rootbp)) {
1196 dn->dn_dirtyctx =
1197 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN);
1198 ASSERT(dn->dn_dirtyctx_firstset == NULL);
1199 dn->dn_dirtyctx_firstset = kmem_alloc(1, KM_SLEEP);
1200 }
1201 mutex_exit(&dn->dn_mtx);
1202
1203 if (db->db_blkid == DMU_SPILL_BLKID)
1204 dn->dn_have_spill = B_TRUE;
1205
1206 /*
1207 * If this buffer is already dirty, we're done.
1208 */
1209 drp = &db->db_last_dirty;
1210 ASSERT(*drp == NULL || (*drp)->dr_txg <= tx->tx_txg ||
1211 db->db.db_object == DMU_META_DNODE_OBJECT);
1212 while ((dr = *drp) != NULL && dr->dr_txg > tx->tx_txg)
1213 drp = &dr->dr_next;
1214 if (dr && dr->dr_txg == tx->tx_txg) {
1215 DB_DNODE_EXIT(db);
1216
1217 dbuf_redirty(dr);
1218 mutex_exit(&db->db_mtx);
1219 return (dr);
1220 }
1221
1222 /*
1223 * Only valid if not already dirty.
1224 */
1225 ASSERT(dn->dn_object == 0 ||
1226 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1227 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1228
1229 ASSERT3U(dn->dn_nlevels, >, db->db_level);
1230 ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) ||
1231 dn->dn_phys->dn_nlevels > db->db_level ||
1232 dn->dn_next_nlevels[txgoff] > db->db_level ||
1233 dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level ||
1234 dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level);
1235
1236 /*
1237 * We should only be dirtying in syncing context if it's the
1238 * mos or we're initializing the os or it's a special object.
1239 * However, we are allowed to dirty in syncing context provided
1240 * we already dirtied it in open context. Hence we must make
1241 * this assertion only if we're not already dirty.
1242 */
1243 os = dn->dn_objset;
1244 ASSERT(!dmu_tx_is_syncing(tx) || DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1245 os->os_dsl_dataset == NULL || BP_IS_HOLE(os->os_rootbp));
1246 ASSERT(db->db.db_size != 0);
1247
1248 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1249
1250 if (db->db_blkid != DMU_BONUS_BLKID) {
1251 /*
1252 * Update the accounting.
1253 * Note: we delay "free accounting" until after we drop
1254 * the db_mtx. This keeps us from grabbing other locks
1255 * (and possibly deadlocking) in bp_get_dsize() while
1256 * also holding the db_mtx.
1257 */
1258 dnode_willuse_space(dn, db->db.db_size, tx);
1259 do_free_accounting = dbuf_block_freeable(db);
1260 }
1261
1262 /*
1263 * If this buffer is dirty in an old transaction group we need
1264 * to make a copy of it so that the changes we make in this
1265 * transaction group won't leak out when we sync the older txg.
1266 */
1267 dr = kmem_zalloc(sizeof (dbuf_dirty_record_t), KM_SLEEP);
1268 if (db->db_level == 0) {
1269 void *data_old = db->db_buf;
1270
1271 if (db->db_state != DB_NOFILL) {
1272 if (db->db_blkid == DMU_BONUS_BLKID) {
1273 dbuf_fix_old_data(db, tx->tx_txg);
1274 data_old = db->db.db_data;
1275 } else if (db->db.db_object != DMU_META_DNODE_OBJECT) {
1276 /*
1277 * Release the data buffer from the cache so
1278 * that we can modify it without impacting
1279 * possible other users of this cached data
1280 * block. Note that indirect blocks and
1281 * private objects are not released until the
1282 * syncing state (since they are only modified
1283 * then).
1284 */
1285 arc_release(db->db_buf, db);
1286 dbuf_fix_old_data(db, tx->tx_txg);
1287 data_old = db->db_buf;
1288 }
1289 ASSERT(data_old != NULL);
1290 }
1291 dr->dt.dl.dr_data = data_old;
1292 } else {
1293 mutex_init(&dr->dt.di.dr_mtx, NULL, MUTEX_DEFAULT, NULL);
1294 list_create(&dr->dt.di.dr_children,
1295 sizeof (dbuf_dirty_record_t),
1296 offsetof(dbuf_dirty_record_t, dr_dirty_node));
1297 }
1298 if (db->db_blkid != DMU_BONUS_BLKID && os->os_dsl_dataset != NULL)
1299 dr->dr_accounted = db->db.db_size;
1300 dr->dr_dbuf = db;
1301 dr->dr_txg = tx->tx_txg;
1302 dr->dr_next = *drp;
1303 *drp = dr;
1304
1305 /*
1306 * We could have been freed_in_flight between the dbuf_noread
1307 * and dbuf_dirty. We win, as though the dbuf_noread() had
1308 * happened after the free.
1309 */
1310 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
1311 db->db_blkid != DMU_SPILL_BLKID) {
1312 mutex_enter(&dn->dn_mtx);
1313 if (dn->dn_free_ranges[txgoff] != NULL) {
1314 range_tree_clear(dn->dn_free_ranges[txgoff],
1315 db->db_blkid, 1);
1316 }
1317 mutex_exit(&dn->dn_mtx);
1318 db->db_freed_in_flight = FALSE;
1319 }
1320
1321 /*
1322 * This buffer is now part of this txg
1323 */
1324 dbuf_add_ref(db, (void *)(uintptr_t)tx->tx_txg);
1325 db->db_dirtycnt += 1;
1326 ASSERT3U(db->db_dirtycnt, <=, 3);
1327
1328 mutex_exit(&db->db_mtx);
1329
1330 if (db->db_blkid == DMU_BONUS_BLKID ||
1331 db->db_blkid == DMU_SPILL_BLKID) {
1332 mutex_enter(&dn->dn_mtx);
1333 ASSERT(!list_link_active(&dr->dr_dirty_node));
1334 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1335 mutex_exit(&dn->dn_mtx);
1336 dnode_setdirty(dn, tx);
1337 DB_DNODE_EXIT(db);
1338 return (dr);
1339 } else if (do_free_accounting) {
1340 blkptr_t *bp = db->db_blkptr;
1341 int64_t willfree = (bp && !BP_IS_HOLE(bp)) ?
1342 bp_get_dsize(os->os_spa, bp) : db->db.db_size;
1343 /*
1344 * This is only a guess -- if the dbuf is dirty
1345 * in a previous txg, we don't know how much
1346 * space it will use on disk yet. We should
1347 * really have the struct_rwlock to access
1348 * db_blkptr, but since this is just a guess,
1349 * it's OK if we get an odd answer.
1350 */
1351 ddt_prefetch(os->os_spa, bp);
1352 dnode_willuse_space(dn, -willfree, tx);
1353 }
1354
1355 if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
1356 rw_enter(&dn->dn_struct_rwlock, RW_READER);
1357 drop_struct_lock = TRUE;
1358 }
1359
1360 if (db->db_level == 0) {
1361 dnode_new_blkid(dn, db->db_blkid, tx, drop_struct_lock);
1362 ASSERT(dn->dn_maxblkid >= db->db_blkid);
1363 }
1364
1365 if (db->db_level+1 < dn->dn_nlevels) {
1366 dmu_buf_impl_t *parent = db->db_parent;
1367 dbuf_dirty_record_t *di;
1368 int parent_held = FALSE;
1369
1370 if (db->db_parent == NULL || db->db_parent == dn->dn_dbuf) {
1371 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1372
1373 parent = dbuf_hold_level(dn, db->db_level+1,
1374 db->db_blkid >> epbs, FTAG);
1375 ASSERT(parent != NULL);
1376 parent_held = TRUE;
1377 }
1378 if (drop_struct_lock)
1379 rw_exit(&dn->dn_struct_rwlock);
1380 ASSERT3U(db->db_level+1, ==, parent->db_level);
1381 di = dbuf_dirty(parent, tx);
1382 if (parent_held)
1383 dbuf_rele(parent, FTAG);
1384
1385 mutex_enter(&db->db_mtx);
1386 /*
1387 * Since we've dropped the mutex, it's possible that
1388 * dbuf_undirty() might have changed this out from under us.
1389 */
1390 if (db->db_last_dirty == dr ||
1391 dn->dn_object == DMU_META_DNODE_OBJECT) {
1392 mutex_enter(&di->dt.di.dr_mtx);
1393 ASSERT3U(di->dr_txg, ==, tx->tx_txg);
1394 ASSERT(!list_link_active(&dr->dr_dirty_node));
1395 list_insert_tail(&di->dt.di.dr_children, dr);
1396 mutex_exit(&di->dt.di.dr_mtx);
1397 dr->dr_parent = di;
1398 }
1399 mutex_exit(&db->db_mtx);
1400 } else {
1401 ASSERT(db->db_level+1 == dn->dn_nlevels);
1402 ASSERT(db->db_blkid < dn->dn_nblkptr);
1403 ASSERT(db->db_parent == NULL || db->db_parent == dn->dn_dbuf);
1404 mutex_enter(&dn->dn_mtx);
1405 ASSERT(!list_link_active(&dr->dr_dirty_node));
1406 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1407 mutex_exit(&dn->dn_mtx);
1408 if (drop_struct_lock)
1409 rw_exit(&dn->dn_struct_rwlock);
1410 }
1411
1412 dnode_setdirty(dn, tx);
1413 DB_DNODE_EXIT(db);
1414 return (dr);
1415 }
1416
1417 /*
1418 * Undirty a buffer in the transaction group referenced by the given
1419 * transaction. Return whether this evicted the dbuf.
1420 */
1421 static boolean_t
1422 dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1423 {
1424 dnode_t *dn;
1425 uint64_t txg = tx->tx_txg;
1426 dbuf_dirty_record_t *dr, **drp;
1427
1428 ASSERT(txg != 0);
1429
1430 /*
1431 * Due to our use of dn_nlevels below, this can only be called
1432 * in open context, unless we are operating on the MOS.
1433 * From syncing context, dn_nlevels may be different from the
1434 * dn_nlevels used when dbuf was dirtied.
1435 */
1436 ASSERT(db->db_objset ==
1437 dmu_objset_pool(db->db_objset)->dp_meta_objset ||
1438 txg != spa_syncing_txg(dmu_objset_spa(db->db_objset)));
1439 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1440 ASSERT0(db->db_level);
1441 ASSERT(MUTEX_HELD(&db->db_mtx));
1442
1443 /*
1444 * If this buffer is not dirty, we're done.
1445 */
1446 for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next)
1447 if (dr->dr_txg <= txg)
1448 break;
1449 if (dr == NULL || dr->dr_txg < txg)
1450 return (B_FALSE);
1451 ASSERT(dr->dr_txg == txg);
1452 ASSERT(dr->dr_dbuf == db);
1453
1454 DB_DNODE_ENTER(db);
1455 dn = DB_DNODE(db);
1456
1457 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1458
1459 ASSERT(db->db.db_size != 0);
1460
1461 dsl_pool_undirty_space(dmu_objset_pool(dn->dn_objset),
1462 dr->dr_accounted, txg);
1463
1464 *drp = dr->dr_next;
1465
1466 /*
1467 * Note that there are three places in dbuf_dirty()
1468 * where this dirty record may be put on a list.
1469 * Make sure to do a list_remove corresponding to
1470 * every one of those list_insert calls.
1471 */
1472 if (dr->dr_parent) {
1473 mutex_enter(&dr->dr_parent->dt.di.dr_mtx);
1474 list_remove(&dr->dr_parent->dt.di.dr_children, dr);
1475 mutex_exit(&dr->dr_parent->dt.di.dr_mtx);
1476 } else if (db->db_blkid == DMU_SPILL_BLKID ||
1477 db->db_level + 1 == dn->dn_nlevels) {
1478 ASSERT(db->db_blkptr == NULL || db->db_parent == dn->dn_dbuf);
1479 mutex_enter(&dn->dn_mtx);
1480 list_remove(&dn->dn_dirty_records[txg & TXG_MASK], dr);
1481 mutex_exit(&dn->dn_mtx);
1482 }
1483 DB_DNODE_EXIT(db);
1484
1485 if (db->db_state != DB_NOFILL) {
1486 dbuf_unoverride(dr);
1487
1488 ASSERT(db->db_buf != NULL);
1489 ASSERT(dr->dt.dl.dr_data != NULL);
1490 if (dr->dt.dl.dr_data != db->db_buf)
1491 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data, db));
1492 }
1493
1494 kmem_free(dr, sizeof (dbuf_dirty_record_t));
1495
1496 ASSERT(db->db_dirtycnt > 0);
1497 db->db_dirtycnt -= 1;
1498
1499 if (refcount_remove(&db->db_holds, (void *)(uintptr_t)txg) == 0) {
1500 arc_buf_t *buf = db->db_buf;
1501
1502 ASSERT(db->db_state == DB_NOFILL || arc_released(buf));
1503 dbuf_clear_data(db);
1504 VERIFY(arc_buf_remove_ref(buf, db));
1505 dbuf_evict(db);
1506 return (B_TRUE);
1507 }
1508
1509 return (B_FALSE);
1510 }
1511
1512 void
1513 dmu_buf_will_dirty(dmu_buf_t *db_fake, dmu_tx_t *tx)
1514 {
1515 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1516 int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH;
1517
1518 ASSERT(tx->tx_txg != 0);
1519 ASSERT(!refcount_is_zero(&db->db_holds));
1520
1521 /*
1522 * Quick check for dirtyness. For already dirty blocks, this
1523 * reduces runtime of this function by >90%, and overall performance
1524 * by 50% for some workloads (e.g. file deletion with indirect blocks
1525 * cached).
1526 */
1527 mutex_enter(&db->db_mtx);
1528 dbuf_dirty_record_t *dr;
1529 for (dr = db->db_last_dirty;
1530 dr != NULL && dr->dr_txg >= tx->tx_txg; dr = dr->dr_next) {
1531 /*
1532 * It's possible that it is already dirty but not cached,
1533 * because there are some calls to dbuf_dirty() that don't
1534 * go through dmu_buf_will_dirty().
1535 */
1536 if (dr->dr_txg == tx->tx_txg && db->db_state == DB_CACHED) {
1537 /* This dbuf is already dirty and cached. */
1538 dbuf_redirty(dr);
1539 mutex_exit(&db->db_mtx);
1540 return;
1541 }
1542 }
1543 mutex_exit(&db->db_mtx);
1544
1545 DB_DNODE_ENTER(db);
1546 if (RW_WRITE_HELD(&DB_DNODE(db)->dn_struct_rwlock))
1547 rf |= DB_RF_HAVESTRUCT;
1548 DB_DNODE_EXIT(db);
1549 (void) dbuf_read(db, NULL, rf);
1550 (void) dbuf_dirty(db, tx);
1551 }
1552
1553 void
1554 dmu_buf_will_not_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1555 {
1556 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1557
1558 db->db_state = DB_NOFILL;
1559
1560 dmu_buf_will_fill(db_fake, tx);
1561 }
1562
1563 void
1564 dmu_buf_will_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1565 {
1566 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1567
1568 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1569 ASSERT(tx->tx_txg != 0);
1570 ASSERT(db->db_level == 0);
1571 ASSERT(!refcount_is_zero(&db->db_holds));
1572
1573 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT ||
1574 dmu_tx_private_ok(tx));
1575
1576 dbuf_noread(db);
1577 (void) dbuf_dirty(db, tx);
1578 }
1579
1580 #pragma weak dmu_buf_fill_done = dbuf_fill_done
1581 /* ARGSUSED */
1582 void
1583 dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx)
1584 {
1585 mutex_enter(&db->db_mtx);
1586 DBUF_VERIFY(db);
1587
1588 if (db->db_state == DB_FILL) {
1589 if (db->db_level == 0 && db->db_freed_in_flight) {
1590 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1591 /* we were freed while filling */
1592 /* XXX dbuf_undirty? */
1593 bzero(db->db.db_data, db->db.db_size);
1594 db->db_freed_in_flight = FALSE;
1595 }
1596 db->db_state = DB_CACHED;
1597 cv_broadcast(&db->db_changed);
1598 }
1599 mutex_exit(&db->db_mtx);
1600 }
1601
1602 void
1603 dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
1604 bp_embedded_type_t etype, enum zio_compress comp,
1605 int uncompressed_size, int compressed_size, int byteorder,
1606 dmu_tx_t *tx)
1607 {
1608 dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf;
1609 struct dirty_leaf *dl;
1610 dmu_object_type_t type;
1611
1612 if (etype == BP_EMBEDDED_TYPE_DATA) {
1613 ASSERT(spa_feature_is_active(dmu_objset_spa(db->db_objset),
1614 SPA_FEATURE_EMBEDDED_DATA));
1615 }
1616
1617 DB_DNODE_ENTER(db);
1618 type = DB_DNODE(db)->dn_type;
1619 DB_DNODE_EXIT(db);
1620
1621 ASSERT0(db->db_level);
1622 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1623
1624 dmu_buf_will_not_fill(dbuf, tx);
1625
1626 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
1627 dl = &db->db_last_dirty->dt.dl;
1628 encode_embedded_bp_compressed(&dl->dr_overridden_by,
1629 data, comp, uncompressed_size, compressed_size);
1630 BPE_SET_ETYPE(&dl->dr_overridden_by, etype);
1631 BP_SET_TYPE(&dl->dr_overridden_by, type);
1632 BP_SET_LEVEL(&dl->dr_overridden_by, 0);
1633 BP_SET_BYTEORDER(&dl->dr_overridden_by, byteorder);
1634
1635 dl->dr_override_state = DR_OVERRIDDEN;
1636 dl->dr_overridden_by.blk_birth = db->db_last_dirty->dr_txg;
1637 }
1638
1639 /*
1640 * Directly assign a provided arc buf to a given dbuf if it's not referenced
1641 * by anybody except our caller. Otherwise copy arcbuf's contents to dbuf.
1642 */
1643 void
1644 dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx)
1645 {
1646 ASSERT(!refcount_is_zero(&db->db_holds));
1647 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1648 ASSERT(db->db_level == 0);
1649 ASSERT(DBUF_GET_BUFC_TYPE(db) == ARC_BUFC_DATA);
1650 ASSERT(buf != NULL);
1651 ASSERT(arc_buf_size(buf) == db->db.db_size);
1652 ASSERT(tx->tx_txg != 0);
1653
1654 arc_return_buf(buf, db);
1655 ASSERT(arc_released(buf));
1656
1657 mutex_enter(&db->db_mtx);
1658
1659 while (db->db_state == DB_READ || db->db_state == DB_FILL)
1660 cv_wait(&db->db_changed, &db->db_mtx);
1661
1662 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED);
1663
1664 if (db->db_state == DB_CACHED &&
1665 refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) {
1666 mutex_exit(&db->db_mtx);
1667 (void) dbuf_dirty(db, tx);
1668 bcopy(buf->b_data, db->db.db_data, db->db.db_size);
1669 VERIFY(arc_buf_remove_ref(buf, db));
1670 xuio_stat_wbuf_copied();
1671 return;
1672 }
1673
1674 xuio_stat_wbuf_nocopy();
1675 if (db->db_state == DB_CACHED) {
1676 dbuf_dirty_record_t *dr = db->db_last_dirty;
1677
1678 ASSERT(db->db_buf != NULL);
1679 if (dr != NULL && dr->dr_txg == tx->tx_txg) {
1680 ASSERT(dr->dt.dl.dr_data == db->db_buf);
1681 if (!arc_released(db->db_buf)) {
1682 ASSERT(dr->dt.dl.dr_override_state ==
1683 DR_OVERRIDDEN);
1684 arc_release(db->db_buf, db);
1685 }
1686 dr->dt.dl.dr_data = buf;
1687 VERIFY(arc_buf_remove_ref(db->db_buf, db));
1688 } else if (dr == NULL || dr->dt.dl.dr_data != db->db_buf) {
1689 arc_release(db->db_buf, db);
1690 VERIFY(arc_buf_remove_ref(db->db_buf, db));
1691 }
1692 db->db_buf = NULL;
1693 }
1694 ASSERT(db->db_buf == NULL);
1695 dbuf_set_data(db, buf);
1696 db->db_state = DB_FILL;
1697 mutex_exit(&db->db_mtx);
1698 (void) dbuf_dirty(db, tx);
1699 dmu_buf_fill_done(&db->db, tx);
1700 }
1701
1702 /*
1703 * "Clear" the contents of this dbuf. This will mark the dbuf
1704 * EVICTING and clear *most* of its references. Unfortunately,
1705 * when we are not holding the dn_dbufs_mtx, we can't clear the
1706 * entry in the dn_dbufs list. We have to wait until dbuf_destroy()
1707 * in this case. For callers from the DMU we will usually see:
1708 * dbuf_clear()->arc_clear_callback()->dbuf_do_evict()->dbuf_destroy()
1709 * For the arc callback, we will usually see:
1710 * dbuf_do_evict()->dbuf_clear();dbuf_destroy()
1711 * Sometimes, though, we will get a mix of these two:
1712 * DMU: dbuf_clear()->arc_clear_callback()
1713 * ARC: dbuf_do_evict()->dbuf_destroy()
1714 *
1715 * This routine will dissociate the dbuf from the arc, by calling
1716 * arc_clear_callback(), but will not evict the data from the ARC.
1717 */
1718 void
1719 dbuf_clear(dmu_buf_impl_t *db)
1720 {
1721 dnode_t *dn;
1722 dmu_buf_impl_t *parent = db->db_parent;
1723 dmu_buf_impl_t *dndb;
1724 boolean_t dbuf_gone = B_FALSE;
1725
1726 ASSERT(MUTEX_HELD(&db->db_mtx));
1727 ASSERT(refcount_is_zero(&db->db_holds));
1728
1729 dbuf_evict_user(db);
1730
1731 if (db->db_state == DB_CACHED) {
1732 ASSERT(db->db.db_data != NULL);
1733 if (db->db_blkid == DMU_BONUS_BLKID) {
1734 zio_buf_free(db->db.db_data, DN_MAX_BONUSLEN);
1735 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
1736 }
1737 db->db.db_data = NULL;
1738 db->db_state = DB_UNCACHED;
1739 }
1740
1741 ASSERT(db->db_state == DB_UNCACHED || db->db_state == DB_NOFILL);
1742 ASSERT(db->db_data_pending == NULL);
1743
1744 db->db_state = DB_EVICTING;
1745 db->db_blkptr = NULL;
1746
1747 DB_DNODE_ENTER(db);
1748 dn = DB_DNODE(db);
1749 dndb = dn->dn_dbuf;
1750 if (db->db_blkid != DMU_BONUS_BLKID && MUTEX_HELD(&dn->dn_dbufs_mtx)) {
1751 avl_remove(&dn->dn_dbufs, db);
1752 atomic_dec_32(&dn->dn_dbufs_count);
1753 membar_producer();
1754 DB_DNODE_EXIT(db);
1755 /*
1756 * Decrementing the dbuf count means that the hold corresponding
1757 * to the removed dbuf is no longer discounted in dnode_move(),
1758 * so the dnode cannot be moved until after we release the hold.
1759 * The membar_producer() ensures visibility of the decremented
1760 * value in dnode_move(), since DB_DNODE_EXIT doesn't actually
1761 * release any lock.
1762 */
1763 dnode_rele(dn, db);
1764 db->db_dnode_handle = NULL;
1765 } else {
1766 DB_DNODE_EXIT(db);
1767 }
1768
1769 if (db->db_buf)
1770 dbuf_gone = arc_clear_callback(db->db_buf);
1771
1772 if (!dbuf_gone)
1773 mutex_exit(&db->db_mtx);
1774
1775 /*
1776 * If this dbuf is referenced from an indirect dbuf,
1777 * decrement the ref count on the indirect dbuf.
1778 */
1779 if (parent && parent != dndb)
1780 dbuf_rele(parent, db);
1781 }
1782
1783 /*
1784 * Note: While bpp will always be updated if the function returns success,
1785 * parentp will not be updated if the dnode does not have dn_dbuf filled in;
1786 * this happens when the dnode is the meta-dnode, or a userused or groupused
1787 * object.
1788 */
1789 static int
1790 dbuf_findbp(dnode_t *dn, int level, uint64_t blkid, int fail_sparse,
1791 dmu_buf_impl_t **parentp, blkptr_t **bpp)
1792 {
1793 int nlevels, epbs;
1794
1795 *parentp = NULL;
1796 *bpp = NULL;
1797
1798 ASSERT(blkid != DMU_BONUS_BLKID);
1799
1800 if (blkid == DMU_SPILL_BLKID) {
1801 mutex_enter(&dn->dn_mtx);
1802 if (dn->dn_have_spill &&
1803 (dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR))
1804 *bpp = &dn->dn_phys->dn_spill;
1805 else
1806 *bpp = NULL;
1807 dbuf_add_ref(dn->dn_dbuf, NULL);
1808 *parentp = dn->dn_dbuf;
1809 mutex_exit(&dn->dn_mtx);
1810 return (0);
1811 }
1812
1813 if (dn->dn_phys->dn_nlevels == 0)
1814 nlevels = 1;
1815 else
1816 nlevels = dn->dn_phys->dn_nlevels;
1817
1818 epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1819
1820 ASSERT3U(level * epbs, <, 64);
1821 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1822 if (level >= nlevels ||
1823 (blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))) {
1824 /* the buffer has no parent yet */
1825 return (SET_ERROR(ENOENT));
1826 } else if (level < nlevels-1) {
1827 /* this block is referenced from an indirect block */
1828 int err = dbuf_hold_impl(dn, level+1,
1829 blkid >> epbs, fail_sparse, FALSE, NULL, parentp);
1830 if (err)
1831 return (err);
1832 err = dbuf_read(*parentp, NULL,
1833 (DB_RF_HAVESTRUCT | DB_RF_NOPREFETCH | DB_RF_CANFAIL));
1834 if (err) {
1835 dbuf_rele(*parentp, NULL);
1836 *parentp = NULL;
1837 return (err);
1838 }
1839 *bpp = ((blkptr_t *)(*parentp)->db.db_data) +
1840 (blkid & ((1ULL << epbs) - 1));
1841 return (0);
1842 } else {
1843 /* the block is referenced from the dnode */
1844 ASSERT3U(level, ==, nlevels-1);
1845 ASSERT(dn->dn_phys->dn_nblkptr == 0 ||
1846 blkid < dn->dn_phys->dn_nblkptr);
1847 if (dn->dn_dbuf) {
1848 dbuf_add_ref(dn->dn_dbuf, NULL);
1849 *parentp = dn->dn_dbuf;
1850 }
1851 *bpp = &dn->dn_phys->dn_blkptr[blkid];
1852 return (0);
1853 }
1854 }
1855
1856 static dmu_buf_impl_t *
1857 dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid,
1858 dmu_buf_impl_t *parent, blkptr_t *blkptr)
1859 {
1860 objset_t *os = dn->dn_objset;
1861 dmu_buf_impl_t *db, *odb;
1862
1863 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1864 ASSERT(dn->dn_type != DMU_OT_NONE);
1865
1866 db = kmem_cache_alloc(dbuf_cache, KM_SLEEP);
1867
1868 db->db_objset = os;
1869 db->db.db_object = dn->dn_object;
1870 db->db_level = level;
1871 db->db_blkid = blkid;
1872 db->db_last_dirty = NULL;
1873 db->db_dirtycnt = 0;
1874 db->db_dnode_handle = dn->dn_handle;
1875 db->db_parent = parent;
1876 db->db_blkptr = blkptr;
1877
1878 db->db_user = NULL;
1879 db->db_user_immediate_evict = FALSE;
1880 db->db_freed_in_flight = FALSE;
1881 db->db_pending_evict = FALSE;
1882
1883 if (blkid == DMU_BONUS_BLKID) {
1884 ASSERT3P(parent, ==, dn->dn_dbuf);
1885 db->db.db_size = DN_MAX_BONUSLEN -
1886 (dn->dn_nblkptr-1) * sizeof (blkptr_t);
1887 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
1888 db->db.db_offset = DMU_BONUS_BLKID;
1889 db->db_state = DB_UNCACHED;
1890 /* the bonus dbuf is not placed in the hash table */
1891 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1892 return (db);
1893 } else if (blkid == DMU_SPILL_BLKID) {
1894 db->db.db_size = (blkptr != NULL) ?
1895 BP_GET_LSIZE(blkptr) : SPA_MINBLOCKSIZE;
1896 db->db.db_offset = 0;
1897 } else {
1898 int blocksize =
1899 db->db_level ? 1 << dn->dn_indblkshift : dn->dn_datablksz;
1900 db->db.db_size = blocksize;
1901 db->db.db_offset = db->db_blkid * blocksize;
1902 }
1903
1904 /*
1905 * Hold the dn_dbufs_mtx while we get the new dbuf
1906 * in the hash table *and* added to the dbufs list.
1907 * This prevents a possible deadlock with someone
1908 * trying to look up this dbuf before its added to the
1909 * dn_dbufs list.
1910 */
1911 mutex_enter(&dn->dn_dbufs_mtx);
1912 db->db_state = DB_EVICTING;
1913 if ((odb = dbuf_hash_insert(db)) != NULL) {
1914 /* someone else inserted it first */
1915 kmem_cache_free(dbuf_cache, db);
1916 mutex_exit(&dn->dn_dbufs_mtx);
1917 return (odb);
1918 }
1919 avl_add(&dn->dn_dbufs, db);
1920 if (db->db_level == 0 && db->db_blkid >=
1921 dn->dn_unlisted_l0_blkid)
1922 dn->dn_unlisted_l0_blkid = db->db_blkid + 1;
1923 db->db_state = DB_UNCACHED;
1924 mutex_exit(&dn->dn_dbufs_mtx);
1925 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1926
1927 if (parent && parent != dn->dn_dbuf)
1928 dbuf_add_ref(parent, db);
1929
1930 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1931 refcount_count(&dn->dn_holds) > 0);
1932 (void) refcount_add(&dn->dn_holds, db);
1933 atomic_inc_32(&dn->dn_dbufs_count);
1934
1935 dprintf_dbuf(db, "db=%p\n", db);
1936
1937 return (db);
1938 }
1939
1940 static int
1941 dbuf_do_evict(void *private)
1942 {
1943 dmu_buf_impl_t *db = private;
1944
1945 if (!MUTEX_HELD(&db->db_mtx))
1946 mutex_enter(&db->db_mtx);
1947
1948 ASSERT(refcount_is_zero(&db->db_holds));
1949
1950 if (db->db_state != DB_EVICTING) {
1951 ASSERT(db->db_state == DB_CACHED);
1952 DBUF_VERIFY(db);
1953 db->db_buf = NULL;
1954 dbuf_evict(db);
1955 } else {
1956 mutex_exit(&db->db_mtx);
1957 dbuf_destroy(db);
1958 }
1959 return (0);
1960 }
1961
1962 static void
1963 dbuf_destroy(dmu_buf_impl_t *db)
1964 {
1965 ASSERT(refcount_is_zero(&db->db_holds));
1966
1967 if (db->db_blkid != DMU_BONUS_BLKID) {
1968 /*
1969 * If this dbuf is still on the dn_dbufs list,
1970 * remove it from that list.
1971 */
1972 if (db->db_dnode_handle != NULL) {
1973 dnode_t *dn;
1974
1975 DB_DNODE_ENTER(db);
1976 dn = DB_DNODE(db);
1977 mutex_enter(&dn->dn_dbufs_mtx);
1978 avl_remove(&dn->dn_dbufs, db);
1979 atomic_dec_32(&dn->dn_dbufs_count);
1980 mutex_exit(&dn->dn_dbufs_mtx);
1981 DB_DNODE_EXIT(db);
1982 /*
1983 * Decrementing the dbuf count means that the hold
1984 * corresponding to the removed dbuf is no longer
1985 * discounted in dnode_move(), so the dnode cannot be
1986 * moved until after we release the hold.
1987 */
1988 dnode_rele(dn, db);
1989 db->db_dnode_handle = NULL;
1990 }
1991 dbuf_hash_remove(db);
1992 }
1993 db->db_parent = NULL;
1994 db->db_buf = NULL;
1995
1996 ASSERT(db->db.db_data == NULL);
1997 ASSERT(db->db_hash_next == NULL);
1998 ASSERT(db->db_blkptr == NULL);
1999 ASSERT(db->db_data_pending == NULL);
2000
2001 kmem_cache_free(dbuf_cache, db);
2002 arc_space_return(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
2003 }
2004
2005 typedef struct dbuf_prefetch_arg {
2006 spa_t *dpa_spa; /* The spa to issue the prefetch in. */
2007 zbookmark_phys_t dpa_zb; /* The target block to prefetch. */
2008 int dpa_epbs; /* Entries (blkptr_t's) Per Block Shift. */
2009 int dpa_curlevel; /* The current level that we're reading */
2010 zio_priority_t dpa_prio; /* The priority I/Os should be issued at. */
2011 zio_t *dpa_zio; /* The parent zio_t for all prefetches. */
2012 arc_flags_t dpa_aflags; /* Flags to pass to the final prefetch. */
2013 } dbuf_prefetch_arg_t;
2014
2015 /*
2016 * Actually issue the prefetch read for the block given.
2017 */
2018 static void
2019 dbuf_issue_final_prefetch(dbuf_prefetch_arg_t *dpa, blkptr_t *bp)
2020 {
2021 if (BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp))
2022 return;
2023
2024 arc_flags_t aflags =
2025 dpa->dpa_aflags | ARC_FLAG_NOWAIT | ARC_FLAG_PREFETCH;
2026
2027 ASSERT3U(dpa->dpa_curlevel, ==, BP_GET_LEVEL(bp));
2028 ASSERT3U(dpa->dpa_curlevel, ==, dpa->dpa_zb.zb_level);
2029 ASSERT(dpa->dpa_zio != NULL);
2030 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa, bp, NULL, NULL,
2031 dpa->dpa_prio, ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
2032 &aflags, &dpa->dpa_zb);
2033 }
2034
2035 /*
2036 * Called when an indirect block above our prefetch target is read in. This
2037 * will either read in the next indirect block down the tree or issue the actual
2038 * prefetch if the next block down is our target.
2039 */
2040 static void
2041 dbuf_prefetch_indirect_done(zio_t *zio, arc_buf_t *abuf, void *private)
2042 {
2043 dbuf_prefetch_arg_t *dpa = private;
2044
2045 ASSERT3S(dpa->dpa_zb.zb_level, <, dpa->dpa_curlevel);
2046 ASSERT3S(dpa->dpa_curlevel, >, 0);
2047 if (zio != NULL) {
2048 ASSERT3S(BP_GET_LEVEL(zio->io_bp), ==, dpa->dpa_curlevel);
2049 ASSERT3U(BP_GET_LSIZE(zio->io_bp), ==, zio->io_size);
2050 ASSERT3P(zio->io_spa, ==, dpa->dpa_spa);
2051 }
2052
2053 dpa->dpa_curlevel--;
2054
2055 uint64_t nextblkid = dpa->dpa_zb.zb_blkid >>
2056 (dpa->dpa_epbs * (dpa->dpa_curlevel - dpa->dpa_zb.zb_level));
2057 blkptr_t *bp = ((blkptr_t *)abuf->b_data) +
2058 P2PHASE(nextblkid, 1ULL << dpa->dpa_epbs);
2059 if (BP_IS_HOLE(bp) || (zio != NULL && zio->io_error != 0)) {
2060 kmem_free(dpa, sizeof (*dpa));
2061 } else if (dpa->dpa_curlevel == dpa->dpa_zb.zb_level) {
2062 ASSERT3U(nextblkid, ==, dpa->dpa_zb.zb_blkid);
2063 dbuf_issue_final_prefetch(dpa, bp);
2064 kmem_free(dpa, sizeof (*dpa));
2065 } else {
2066 arc_flags_t iter_aflags = ARC_FLAG_NOWAIT;
2067 zbookmark_phys_t zb;
2068
2069 ASSERT3U(dpa->dpa_curlevel, ==, BP_GET_LEVEL(bp));
2070
2071 SET_BOOKMARK(&zb, dpa->dpa_zb.zb_objset,
2072 dpa->dpa_zb.zb_object, dpa->dpa_curlevel, nextblkid);
2073
2074 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa,
2075 bp, dbuf_prefetch_indirect_done, dpa, dpa->dpa_prio,
2076 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
2077 &iter_aflags, &zb);
2078 }
2079 (void) arc_buf_remove_ref(abuf, private);
2080 }
2081
2082 /*
2083 * Issue prefetch reads for the given block on the given level. If the indirect
2084 * blocks above that block are not in memory, we will read them in
2085 * asynchronously. As a result, this call never blocks waiting for a read to
2086 * complete.
2087 */
2088 void
2089 dbuf_prefetch(dnode_t *dn, int64_t level, uint64_t blkid, zio_priority_t prio,
2090 arc_flags_t aflags)
2091 {
2092 blkptr_t bp;
2093 int epbs, nlevels, curlevel;
2094 uint64_t curblkid;
2095
2096 ASSERT(blkid != DMU_BONUS_BLKID);
2097 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
2098
2099 if (blkid > dn->dn_maxblkid)
2100 return;
2101
2102 if (dnode_block_freed(dn, blkid))
2103 return;
2104
2105 /*
2106 * This dnode hasn't been written to disk yet, so there's nothing to
2107 * prefetch.
2108 */
2109 nlevels = dn->dn_phys->dn_nlevels;
2110 if (level >= nlevels || dn->dn_phys->dn_nblkptr == 0)
2111 return;
2112
2113 epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2114 if (dn->dn_phys->dn_maxblkid < blkid << (epbs * level))
2115 return;
2116
2117 dmu_buf_impl_t *db = dbuf_find(dn->dn_objset, dn->dn_object,
2118 level, blkid);
2119 if (db != NULL) {
2120 mutex_exit(&db->db_mtx);
2121 /*
2122 * This dbuf already exists. It is either CACHED, or
2123 * (we assume) about to be read or filled.
2124 */
2125 return;
2126 }
2127
2128 /*
2129 * Find the closest ancestor (indirect block) of the target block
2130 * that is present in the cache. In this indirect block, we will
2131 * find the bp that is at curlevel, curblkid.
2132 */
2133 curlevel = level;
2134 curblkid = blkid;
2135 while (curlevel < nlevels - 1) {
2136 int parent_level = curlevel + 1;
2137 uint64_t parent_blkid = curblkid >> epbs;
2138 dmu_buf_impl_t *db;
2139
2140 if (dbuf_hold_impl(dn, parent_level, parent_blkid,
2141 FALSE, TRUE, FTAG, &db) == 0) {
2142 blkptr_t *bpp = db->db_buf->b_data;
2143 bp = bpp[P2PHASE(curblkid, 1 << epbs)];
2144 dbuf_rele(db, FTAG);
2145 break;
2146 }
2147
2148 curlevel = parent_level;
2149 curblkid = parent_blkid;
2150 }
2151
2152 if (curlevel == nlevels - 1) {
2153 /* No cached indirect blocks found. */
2154 ASSERT3U(curblkid, <, dn->dn_phys->dn_nblkptr);
2155 bp = dn->dn_phys->dn_blkptr[curblkid];
2156 }
2157 if (BP_IS_HOLE(&bp))
2158 return;
2159
2160 ASSERT3U(curlevel, ==, BP_GET_LEVEL(&bp));
2161
2162 zio_t *pio = zio_root(dmu_objset_spa(dn->dn_objset), NULL, NULL,
2163 ZIO_FLAG_CANFAIL);
2164
2165 dbuf_prefetch_arg_t *dpa = kmem_zalloc(sizeof (*dpa), KM_SLEEP);
2166 dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset;
2167 SET_BOOKMARK(&dpa->dpa_zb, ds != NULL ? ds->ds_object : DMU_META_OBJSET,
2168 dn->dn_object, level, blkid);
2169 dpa->dpa_curlevel = curlevel;
2170 dpa->dpa_prio = prio;
2171 dpa->dpa_aflags = aflags;
2172 dpa->dpa_spa = dn->dn_objset->os_spa;
2173 dpa->dpa_epbs = epbs;
2174 dpa->dpa_zio = pio;
2175
2176 /*
2177 * If we have the indirect just above us, no need to do the asynchronous
2178 * prefetch chain; we'll just run the last step ourselves. If we're at
2179 * a higher level, though, we want to issue the prefetches for all the
2180 * indirect blocks asynchronously, so we can go on with whatever we were
2181 * doing.
2182 */
2183 if (curlevel == level) {
2184 ASSERT3U(curblkid, ==, blkid);
2185 dbuf_issue_final_prefetch(dpa, &bp);
2186 kmem_free(dpa, sizeof (*dpa));
2187 } else {
2188 arc_flags_t iter_aflags = ARC_FLAG_NOWAIT;
2189 zbookmark_phys_t zb;
2190
2191 SET_BOOKMARK(&zb, ds != NULL ? ds->ds_object : DMU_META_OBJSET,
2192 dn->dn_object, curlevel, curblkid);
2193 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa,
2194 &bp, dbuf_prefetch_indirect_done, dpa, prio,
2195 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
2196 &iter_aflags, &zb);
2197 }
2198 /*
2199 * We use pio here instead of dpa_zio since it's possible that
2200 * dpa may have already been freed.
2201 */
2202 zio_nowait(pio);
2203 }
2204
2205 /*
2206 * Returns with db_holds incremented, and db_mtx not held.
2207 * Note: dn_struct_rwlock must be held.
2208 */
2209 int
2210 dbuf_hold_impl(dnode_t *dn, uint8_t level, uint64_t blkid,
2211 boolean_t fail_sparse, boolean_t fail_uncached,
2212 void *tag, dmu_buf_impl_t **dbp)
2213 {
2214 dmu_buf_impl_t *db, *parent = NULL;
2215
2216 ASSERT(blkid != DMU_BONUS_BLKID);
2217 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
2218 ASSERT3U(dn->dn_nlevels, >, level);
2219
2220 *dbp = NULL;
2221 top:
2222 /* dbuf_find() returns with db_mtx held */
2223 db = dbuf_find(dn->dn_objset, dn->dn_object, level, blkid);
2224
2225 if (db == NULL) {
2226 blkptr_t *bp = NULL;
2227 int err;
2228
2229 if (fail_uncached)
2230 return (SET_ERROR(ENOENT));
2231
2232 ASSERT3P(parent, ==, NULL);
2233 err = dbuf_findbp(dn, level, blkid, fail_sparse, &parent, &bp);
2234 if (fail_sparse) {
2235 if (err == 0 && bp && BP_IS_HOLE(bp))
2236 err = SET_ERROR(ENOENT);
2237 if (err) {
2238 if (parent)
2239 dbuf_rele(parent, NULL);
2240 return (err);
2241 }
2242 }
2243 if (err && err != ENOENT)
2244 return (err);
2245 db = dbuf_create(dn, level, blkid, parent, bp);
2246 }
2247
2248 if (fail_uncached && db->db_state != DB_CACHED) {
2249 mutex_exit(&db->db_mtx);
2250 return (SET_ERROR(ENOENT));
2251 }
2252
2253 if (db->db_buf && refcount_is_zero(&db->db_holds)) {
2254 arc_buf_add_ref(db->db_buf, db);
2255 if (db->db_buf->b_data == NULL) {
2256 dbuf_clear(db);
2257 if (parent) {
2258 dbuf_rele(parent, NULL);
2259 parent = NULL;
2260 }
2261 goto top;
2262 }
2263 ASSERT3P(db->db.db_data, ==, db->db_buf->b_data);
2264 }
2265
2266 ASSERT(db->db_buf == NULL || arc_referenced(db->db_buf));
2267
2268 /*
2269 * If this buffer is currently syncing out, and we are are
2270 * still referencing it from db_data, we need to make a copy
2271 * of it in case we decide we want to dirty it again in this txg.
2272 */
2273 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
2274 dn->dn_object != DMU_META_DNODE_OBJECT &&
2275 db->db_state == DB_CACHED && db->db_data_pending) {
2276 dbuf_dirty_record_t *dr = db->db_data_pending;
2277
2278 if (dr->dt.dl.dr_data == db->db_buf) {
2279 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
2280
2281 dbuf_set_data(db,
2282 arc_buf_alloc(dn->dn_objset->os_spa,
2283 db->db.db_size, db, type));
2284 bcopy(dr->dt.dl.dr_data->b_data, db->db.db_data,
2285 db->db.db_size);
2286 }
2287 }
2288
2289 (void) refcount_add(&db->db_holds, tag);
2290 DBUF_VERIFY(db);
2291 mutex_exit(&db->db_mtx);
2292
2293 /* NOTE: we can't rele the parent until after we drop the db_mtx */
2294 if (parent)
2295 dbuf_rele(parent, NULL);
2296
2297 ASSERT3P(DB_DNODE(db), ==, dn);
2298 ASSERT3U(db->db_blkid, ==, blkid);
2299 ASSERT3U(db->db_level, ==, level);
2300 *dbp = db;
2301
2302 return (0);
2303 }
2304
2305 dmu_buf_impl_t *
2306 dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag)
2307 {
2308 return (dbuf_hold_level(dn, 0, blkid, tag));
2309 }
2310
2311 dmu_buf_impl_t *
2312 dbuf_hold_level(dnode_t *dn, int level, uint64_t blkid, void *tag)
2313 {
2314 dmu_buf_impl_t *db;
2315 int err = dbuf_hold_impl(dn, level, blkid, FALSE, FALSE, tag, &db);
2316 return (err ? NULL : db);
2317 }
2318
2319 void
2320 dbuf_create_bonus(dnode_t *dn)
2321 {
2322 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
2323
2324 ASSERT(dn->dn_bonus == NULL);
2325 dn->dn_bonus = dbuf_create(dn, 0, DMU_BONUS_BLKID, dn->dn_dbuf, NULL);
2326 }
2327
2328 int
2329 dbuf_spill_set_blksz(dmu_buf_t *db_fake, uint64_t blksz, dmu_tx_t *tx)
2330 {
2331 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2332 dnode_t *dn;
2333
2334 if (db->db_blkid != DMU_SPILL_BLKID)
2335 return (SET_ERROR(ENOTSUP));
2336 if (blksz == 0)
2337 blksz = SPA_MINBLOCKSIZE;
2338 ASSERT3U(blksz, <=, spa_maxblocksize(dmu_objset_spa(db->db_objset)));
2339 blksz = P2ROUNDUP(blksz, SPA_MINBLOCKSIZE);
2340
2341 DB_DNODE_ENTER(db);
2342 dn = DB_DNODE(db);
2343 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
2344 dbuf_new_size(db, blksz, tx);
2345 rw_exit(&dn->dn_struct_rwlock);
2346 DB_DNODE_EXIT(db);
2347
2348 return (0);
2349 }
2350
2351 void
2352 dbuf_rm_spill(dnode_t *dn, dmu_tx_t *tx)
2353 {
2354 dbuf_free_range(dn, DMU_SPILL_BLKID, DMU_SPILL_BLKID, tx);
2355 }
2356
2357 #pragma weak dmu_buf_add_ref = dbuf_add_ref
2358 void
2359 dbuf_add_ref(dmu_buf_impl_t *db, void *tag)
2360 {
2361 int64_t holds = refcount_add(&db->db_holds, tag);
2362 ASSERT(holds > 1);
2363 }
2364
2365 #pragma weak dmu_buf_try_add_ref = dbuf_try_add_ref
2366 boolean_t
2367 dbuf_try_add_ref(dmu_buf_t *db_fake, objset_t *os, uint64_t obj, uint64_t blkid,
2368 void *tag)
2369 {
2370 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2371 dmu_buf_impl_t *found_db;
2372 boolean_t result = B_FALSE;
2373
2374 if (db->db_blkid == DMU_BONUS_BLKID)
2375 found_db = dbuf_find_bonus(os, obj);
2376 else
2377 found_db = dbuf_find(os, obj, 0, blkid);
2378
2379 if (found_db != NULL) {
2380 if (db == found_db && dbuf_refcount(db) > db->db_dirtycnt) {
2381 (void) refcount_add(&db->db_holds, tag);
2382 result = B_TRUE;
2383 }
2384 mutex_exit(&db->db_mtx);
2385 }
2386 return (result);
2387 }
2388
2389 /*
2390 * If you call dbuf_rele() you had better not be referencing the dnode handle
2391 * unless you have some other direct or indirect hold on the dnode. (An indirect
2392 * hold is a hold on one of the dnode's dbufs, including the bonus buffer.)
2393 * Without that, the dbuf_rele() could lead to a dnode_rele() followed by the
2394 * dnode's parent dbuf evicting its dnode handles.
2395 */
2396 void
2397 dbuf_rele(dmu_buf_impl_t *db, void *tag)
2398 {
2399 mutex_enter(&db->db_mtx);
2400 dbuf_rele_and_unlock(db, tag);
2401 }
2402
2403 void
2404 dmu_buf_rele(dmu_buf_t *db, void *tag)
2405 {
2406 dbuf_rele((dmu_buf_impl_t *)db, tag);
2407 }
2408
2409 /*
2410 * dbuf_rele() for an already-locked dbuf. This is necessary to allow
2411 * db_dirtycnt and db_holds to be updated atomically.
2412 */
2413 void
2414 dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag)
2415 {
2416 int64_t holds;
2417
2418 ASSERT(MUTEX_HELD(&db->db_mtx));
2419 DBUF_VERIFY(db);
2420
2421 /*
2422 * Remove the reference to the dbuf before removing its hold on the
2423 * dnode so we can guarantee in dnode_move() that a referenced bonus
2424 * buffer has a corresponding dnode hold.
2425 */
2426 holds = refcount_remove(&db->db_holds, tag);
2427 ASSERT(holds >= 0);
2428
2429 /*
2430 * We can't freeze indirects if there is a possibility that they
2431 * may be modified in the current syncing context.
2432 */
2433 if (db->db_buf && holds == (db->db_level == 0 ? db->db_dirtycnt : 0))
2434 arc_buf_freeze(db->db_buf);
2435
2436 if (holds == db->db_dirtycnt &&
2437 db->db_level == 0 && db->db_user_immediate_evict)
2438 dbuf_evict_user(db);
2439
2440 if (holds == 0) {
2441 if (db->db_blkid == DMU_BONUS_BLKID) {
2442 dnode_t *dn;
2443 boolean_t evict_dbuf = db->db_pending_evict;
2444
2445 /*
2446 * If the dnode moves here, we cannot cross this
2447 * barrier until the move completes.
2448 */
2449 DB_DNODE_ENTER(db);
2450
2451 dn = DB_DNODE(db);
2452 atomic_dec_32(&dn->dn_dbufs_count);
2453
2454 /*
2455 * Decrementing the dbuf count means that the bonus
2456 * buffer's dnode hold is no longer discounted in
2457 * dnode_move(). The dnode cannot move until after
2458 * the dnode_rele() below.
2459 */
2460 DB_DNODE_EXIT(db);
2461
2462 /*
2463 * Do not reference db after its lock is dropped.
2464 * Another thread may evict it.
2465 */
2466 mutex_exit(&db->db_mtx);
2467
2468 if (evict_dbuf)
2469 dnode_evict_bonus(dn);
2470
2471 dnode_rele(dn, db);
2472 } else if (db->db_buf == NULL) {
2473 /*
2474 * This is a special case: we never associated this
2475 * dbuf with any data allocated from the ARC.
2476 */
2477 ASSERT(db->db_state == DB_UNCACHED ||
2478 db->db_state == DB_NOFILL);
2479 dbuf_evict(db);
2480 } else if (arc_released(db->db_buf)) {
2481 arc_buf_t *buf = db->db_buf;
2482 /*
2483 * This dbuf has anonymous data associated with it.
2484 */
2485 dbuf_clear_data(db);
2486 VERIFY(arc_buf_remove_ref(buf, db));
2487 dbuf_evict(db);
2488 } else {
2489 VERIFY(!arc_buf_remove_ref(db->db_buf, db));
2490
2491 /*
2492 * A dbuf will be eligible for eviction if either the
2493 * 'primarycache' property is set or a duplicate
2494 * copy of this buffer is already cached in the arc.
2495 *
2496 * In the case of the 'primarycache' a buffer
2497 * is considered for eviction if it matches the
2498 * criteria set in the property.
2499 *
2500 * To decide if our buffer is considered a
2501 * duplicate, we must call into the arc to determine
2502 * if multiple buffers are referencing the same
2503 * block on-disk. If so, then we simply evict
2504 * ourselves.
2505 */
2506 if (!DBUF_IS_CACHEABLE(db)) {
2507 if (db->db_blkptr != NULL &&
2508 !BP_IS_HOLE(db->db_blkptr) &&
2509 !BP_IS_EMBEDDED(db->db_blkptr)) {
2510 spa_t *spa =
2511 dmu_objset_spa(db->db_objset);
2512 blkptr_t bp = *db->db_blkptr;
2513 dbuf_clear(db);
2514 arc_freed(spa, &bp);
2515 } else {
2516 dbuf_clear(db);
2517 }
2518 } else if (db->db_pending_evict ||
2519 arc_buf_eviction_needed(db->db_buf)) {
2520 dbuf_clear(db);
2521 } else {
2522 mutex_exit(&db->db_mtx);
2523 }
2524 }
2525 } else {
2526 mutex_exit(&db->db_mtx);
2527 }
2528 }
2529
2530 #pragma weak dmu_buf_refcount = dbuf_refcount
2531 uint64_t
2532 dbuf_refcount(dmu_buf_impl_t *db)
2533 {
2534 return (refcount_count(&db->db_holds));
2535 }
2536
2537 void *
2538 dmu_buf_replace_user(dmu_buf_t *db_fake, dmu_buf_user_t *old_user,
2539 dmu_buf_user_t *new_user)
2540 {
2541 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2542
2543 mutex_enter(&db->db_mtx);
2544 dbuf_verify_user(db, DBVU_NOT_EVICTING);
2545 if (db->db_user == old_user)
2546 db->db_user = new_user;
2547 else
2548 old_user = db->db_user;
2549 dbuf_verify_user(db, DBVU_NOT_EVICTING);
2550 mutex_exit(&db->db_mtx);
2551
2552 return (old_user);
2553 }
2554
2555 void *
2556 dmu_buf_set_user(dmu_buf_t *db_fake, dmu_buf_user_t *user)
2557 {
2558 return (dmu_buf_replace_user(db_fake, NULL, user));
2559 }
2560
2561 void *
2562 dmu_buf_set_user_ie(dmu_buf_t *db_fake, dmu_buf_user_t *user)
2563 {
2564 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2565
2566 db->db_user_immediate_evict = TRUE;
2567 return (dmu_buf_set_user(db_fake, user));
2568 }
2569
2570 void *
2571 dmu_buf_remove_user(dmu_buf_t *db_fake, dmu_buf_user_t *user)
2572 {
2573 return (dmu_buf_replace_user(db_fake, user, NULL));
2574 }
2575
2576 void *
2577 dmu_buf_get_user(dmu_buf_t *db_fake)
2578 {
2579 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2580
2581 dbuf_verify_user(db, DBVU_NOT_EVICTING);
2582 return (db->db_user);
2583 }
2584
2585 void
2586 dmu_buf_user_evict_wait()
2587 {
2588 taskq_wait(dbu_evict_taskq);
2589 }
2590
2591 boolean_t
2592 dmu_buf_freeable(dmu_buf_t *dbuf)
2593 {
2594 boolean_t res = B_FALSE;
2595 dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf;
2596
2597 if (db->db_blkptr)
2598 res = dsl_dataset_block_freeable(db->db_objset->os_dsl_dataset,
2599 db->db_blkptr, db->db_blkptr->blk_birth);
2600
2601 return (res);
2602 }
2603
2604 blkptr_t *
2605 dmu_buf_get_blkptr(dmu_buf_t *db)
2606 {
2607 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
2608 return (dbi->db_blkptr);
2609 }
2610
2611 static void
2612 dbuf_check_blkptr(dnode_t *dn, dmu_buf_impl_t *db)
2613 {
2614 /* ASSERT(dmu_tx_is_syncing(tx) */
2615 ASSERT(MUTEX_HELD(&db->db_mtx));
2616
2617 if (db->db_blkptr != NULL)
2618 return;
2619
2620 if (db->db_blkid == DMU_SPILL_BLKID) {
2621 db->db_blkptr = &dn->dn_phys->dn_spill;
2622 BP_ZERO(db->db_blkptr);
2623 return;
2624 }
2625 if (db->db_level == dn->dn_phys->dn_nlevels-1) {
2626 /*
2627 * This buffer was allocated at a time when there was
2628 * no available blkptrs from the dnode, or it was
2629 * inappropriate to hook it in (i.e., nlevels mis-match).
2630 */
2631 ASSERT(db->db_blkid < dn->dn_phys->dn_nblkptr);
2632 ASSERT(db->db_parent == NULL);
2633 db->db_parent = dn->dn_dbuf;
2634 db->db_blkptr = &dn->dn_phys->dn_blkptr[db->db_blkid];
2635 DBUF_VERIFY(db);
2636 } else {
2637 dmu_buf_impl_t *parent = db->db_parent;
2638 int epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2639
2640 ASSERT(dn->dn_phys->dn_nlevels > 1);
2641 if (parent == NULL) {
2642 mutex_exit(&db->db_mtx);
2643 rw_enter(&dn->dn_struct_rwlock, RW_READER);
2644 parent = dbuf_hold_level(dn, db->db_level + 1,
2645 db->db_blkid >> epbs, db);
2646 rw_exit(&dn->dn_struct_rwlock);
2647 mutex_enter(&db->db_mtx);
2648 db->db_parent = parent;
2649 }
2650 db->db_blkptr = (blkptr_t *)parent->db.db_data +
2651 (db->db_blkid & ((1ULL << epbs) - 1));
2652 DBUF_VERIFY(db);
2653 }
2654 }
2655
2656 static void
2657 dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
2658 {
2659 dmu_buf_impl_t *db = dr->dr_dbuf;
2660 dnode_t *dn;
2661 zio_t *zio;
2662
2663 ASSERT(dmu_tx_is_syncing(tx));
2664
2665 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
2666
2667 mutex_enter(&db->db_mtx);
2668
2669 ASSERT(db->db_level > 0);
2670 DBUF_VERIFY(db);
2671
2672 /* Read the block if it hasn't been read yet. */
2673 if (db->db_buf == NULL) {
2674 mutex_exit(&db->db_mtx);
2675 (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED);
2676 mutex_enter(&db->db_mtx);
2677 }
2678 ASSERT3U(db->db_state, ==, DB_CACHED);
2679 ASSERT(db->db_buf != NULL);
2680
2681 DB_DNODE_ENTER(db);
2682 dn = DB_DNODE(db);
2683 /* Indirect block size must match what the dnode thinks it is. */
2684 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2685 dbuf_check_blkptr(dn, db);
2686 DB_DNODE_EXIT(db);
2687
2688 /* Provide the pending dirty record to child dbufs */
2689 db->db_data_pending = dr;
2690
2691 mutex_exit(&db->db_mtx);
2692 dbuf_write(dr, db->db_buf, tx);
2693
2694 zio = dr->dr_zio;
2695 mutex_enter(&dr->dt.di.dr_mtx);
2696 dbuf_sync_list(&dr->dt.di.dr_children, db->db_level - 1, tx);
2697 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
2698 mutex_exit(&dr->dt.di.dr_mtx);
2699 zio_nowait(zio);
2700 }
2701
2702 static void
2703 dbuf_sync_leaf(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
2704 {
2705 arc_buf_t **datap = &dr->dt.dl.dr_data;
2706 dmu_buf_impl_t *db = dr->dr_dbuf;
2707 dnode_t *dn;
2708 objset_t *os;
2709 uint64_t txg = tx->tx_txg;
2710
2711 ASSERT(dmu_tx_is_syncing(tx));
2712
2713 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
2714
2715 mutex_enter(&db->db_mtx);
2716 /*
2717 * To be synced, we must be dirtied. But we
2718 * might have been freed after the dirty.
2719 */
2720 if (db->db_state == DB_UNCACHED) {
2721 /* This buffer has been freed since it was dirtied */
2722 ASSERT(db->db.db_data == NULL);
2723 } else if (db->db_state == DB_FILL) {
2724 /* This buffer was freed and is now being re-filled */
2725 ASSERT(db->db.db_data != dr->dt.dl.dr_data);
2726 } else {
2727 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_NOFILL);
2728 }
2729 DBUF_VERIFY(db);
2730
2731 DB_DNODE_ENTER(db);
2732 dn = DB_DNODE(db);
2733
2734 if (db->db_blkid == DMU_SPILL_BLKID) {
2735 mutex_enter(&dn->dn_mtx);
2736 dn->dn_phys->dn_flags |= DNODE_FLAG_SPILL_BLKPTR;
2737 mutex_exit(&dn->dn_mtx);
2738 }
2739
2740 /*
2741 * If this is a bonus buffer, simply copy the bonus data into the
2742 * dnode. It will be written out when the dnode is synced (and it
2743 * will be synced, since it must have been dirty for dbuf_sync to
2744 * be called).
2745 */
2746 if (db->db_blkid == DMU_BONUS_BLKID) {
2747 dbuf_dirty_record_t **drp;
2748
2749 ASSERT(*datap != NULL);
2750 ASSERT0(db->db_level);
2751 ASSERT3U(dn->dn_phys->dn_bonuslen, <=, DN_MAX_BONUSLEN);
2752 bcopy(*datap, DN_BONUS(dn->dn_phys), dn->dn_phys->dn_bonuslen);
2753 DB_DNODE_EXIT(db);
2754
2755 if (*datap != db->db.db_data) {
2756 zio_buf_free(*datap, DN_MAX_BONUSLEN);
2757 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
2758 }
2759 db->db_data_pending = NULL;
2760 drp = &db->db_last_dirty;
2761 while (*drp != dr)
2762 drp = &(*drp)->dr_next;
2763 ASSERT(dr->dr_next == NULL);
2764 ASSERT(dr->dr_dbuf == db);
2765 *drp = dr->dr_next;
2766 kmem_free(dr, sizeof (dbuf_dirty_record_t));
2767 ASSERT(db->db_dirtycnt > 0);
2768 db->db_dirtycnt -= 1;
2769 dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg);
2770 return;
2771 }
2772
2773 os = dn->dn_objset;
2774
2775 /*
2776 * This function may have dropped the db_mtx lock allowing a dmu_sync
2777 * operation to sneak in. As a result, we need to ensure that we
2778 * don't check the dr_override_state until we have returned from
2779 * dbuf_check_blkptr.
2780 */
2781 dbuf_check_blkptr(dn, db);
2782
2783 /*
2784 * If this buffer is in the middle of an immediate write,
2785 * wait for the synchronous IO to complete.
2786 */
2787 while (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC) {
2788 ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
2789 cv_wait(&db->db_changed, &db->db_mtx);
2790 ASSERT(dr->dt.dl.dr_override_state != DR_NOT_OVERRIDDEN);
2791 }
2792
2793 if (db->db_state != DB_NOFILL &&
2794 dn->dn_object != DMU_META_DNODE_OBJECT &&
2795 refcount_count(&db->db_holds) > 1 &&
2796 dr->dt.dl.dr_override_state != DR_OVERRIDDEN &&
2797 *datap == db->db_buf) {
2798 /*
2799 * If this buffer is currently "in use" (i.e., there
2800 * are active holds and db_data still references it),
2801 * then make a copy before we start the write so that
2802 * any modifications from the open txg will not leak
2803 * into this write.
2804 *
2805 * NOTE: this copy does not need to be made for
2806 * objects only modified in the syncing context (e.g.
2807 * DNONE_DNODE blocks).
2808 */
2809 int blksz = arc_buf_size(*datap);
2810 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
2811 *datap = arc_buf_alloc(os->os_spa, blksz, db, type);
2812 bcopy(db->db.db_data, (*datap)->b_data, blksz);
2813 }
2814 db->db_data_pending = dr;
2815
2816 mutex_exit(&db->db_mtx);
2817
2818 dbuf_write(dr, *datap, tx);
2819
2820 ASSERT(!list_link_active(&dr->dr_dirty_node));
2821 if (dn->dn_object == DMU_META_DNODE_OBJECT) {
2822 list_insert_tail(&dn->dn_dirty_records[txg&TXG_MASK], dr);
2823 DB_DNODE_EXIT(db);
2824 } else {
2825 /*
2826 * Although zio_nowait() does not "wait for an IO", it does
2827 * initiate the IO. If this is an empty write it seems plausible
2828 * that the IO could actually be completed before the nowait
2829 * returns. We need to DB_DNODE_EXIT() first in case
2830 * zio_nowait() invalidates the dbuf.
2831 */
2832 DB_DNODE_EXIT(db);
2833 zio_nowait(dr->dr_zio);
2834 }
2835 }
2836
2837 void
2838 dbuf_sync_list(list_t *list, int level, dmu_tx_t *tx)
2839 {
2840 dbuf_dirty_record_t *dr;
2841
2842 while (dr = list_head(list)) {
2843 if (dr->dr_zio != NULL) {
2844 /*
2845 * If we find an already initialized zio then we
2846 * are processing the meta-dnode, and we have finished.
2847 * The dbufs for all dnodes are put back on the list
2848 * during processing, so that we can zio_wait()
2849 * these IOs after initiating all child IOs.
2850 */
2851 ASSERT3U(dr->dr_dbuf->db.db_object, ==,
2852 DMU_META_DNODE_OBJECT);
2853 break;
2854 }
2855 if (dr->dr_dbuf->db_blkid != DMU_BONUS_BLKID &&
2856 dr->dr_dbuf->db_blkid != DMU_SPILL_BLKID) {
2857 VERIFY3U(dr->dr_dbuf->db_level, ==, level);
2858 }
2859 list_remove(list, dr);
2860 if (dr->dr_dbuf->db_level > 0)
2861 dbuf_sync_indirect(dr, tx);
2862 else
2863 dbuf_sync_leaf(dr, tx);
2864 }
2865 }
2866
2867 /* ARGSUSED */
2868 static void
2869 dbuf_write_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
2870 {
2871 dmu_buf_impl_t *db = vdb;
2872 dnode_t *dn;
2873 blkptr_t *bp = zio->io_bp;
2874 blkptr_t *bp_orig = &zio->io_bp_orig;
2875 spa_t *spa = zio->io_spa;
2876 int64_t delta;
2877 uint64_t fill = 0;
2878 int i;
2879
2880 ASSERT3P(db->db_blkptr, ==, bp);
2881
2882 DB_DNODE_ENTER(db);
2883 dn = DB_DNODE(db);
2884 delta = bp_get_dsize_sync(spa, bp) - bp_get_dsize_sync(spa, bp_orig);
2885 dnode_diduse_space(dn, delta - zio->io_prev_space_delta);
2886 zio->io_prev_space_delta = delta;
2887
2888 if (bp->blk_birth != 0) {
2889 ASSERT((db->db_blkid != DMU_SPILL_BLKID &&
2890 BP_GET_TYPE(bp) == dn->dn_type) ||
2891 (db->db_blkid == DMU_SPILL_BLKID &&
2892 BP_GET_TYPE(bp) == dn->dn_bonustype) ||
2893 BP_IS_EMBEDDED(bp));
2894 ASSERT(BP_GET_LEVEL(bp) == db->db_level);
2895 }
2896
2897 mutex_enter(&db->db_mtx);
2898
2899 #ifdef ZFS_DEBUG
2900 if (db->db_blkid == DMU_SPILL_BLKID) {
2901 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
2902 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
2903 db->db_blkptr == &dn->dn_phys->dn_spill);
2904 }
2905 #endif
2906
2907 if (db->db_level == 0) {
2908 mutex_enter(&dn->dn_mtx);
2909 if (db->db_blkid > dn->dn_phys->dn_maxblkid &&
2910 db->db_blkid != DMU_SPILL_BLKID)
2911 dn->dn_phys->dn_maxblkid = db->db_blkid;
2912 mutex_exit(&dn->dn_mtx);
2913
2914 if (dn->dn_type == DMU_OT_DNODE) {
2915 dnode_phys_t *dnp = db->db.db_data;
2916 for (i = db->db.db_size >> DNODE_SHIFT; i > 0;
2917 i--, dnp++) {
2918 if (dnp->dn_type != DMU_OT_NONE)
2919 fill++;
2920 }
2921 } else {
2922 if (BP_IS_HOLE(bp)) {
2923 fill = 0;
2924 } else {
2925 fill = 1;
2926 }
2927 }
2928 } else {
2929 blkptr_t *ibp = db->db.db_data;
2930 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2931 for (i = db->db.db_size >> SPA_BLKPTRSHIFT; i > 0; i--, ibp++) {
2932 if (BP_IS_HOLE(ibp))
2933 continue;
2934 fill += BP_GET_FILL(ibp);
2935 }
2936 }
2937 DB_DNODE_EXIT(db);
2938
2939 if (!BP_IS_EMBEDDED(bp))
2940 bp->blk_fill = fill;
2941
2942 mutex_exit(&db->db_mtx);
2943 }
2944
2945 /*
2946 * The SPA will call this callback several times for each zio - once
2947 * for every physical child i/o (zio->io_phys_children times). This
2948 * allows the DMU to monitor the progress of each logical i/o. For example,
2949 * there may be 2 copies of an indirect block, or many fragments of a RAID-Z
2950 * block. There may be a long delay before all copies/fragments are completed,
2951 * so this callback allows us to retire dirty space gradually, as the physical
2952 * i/os complete.
2953 */
2954 /* ARGSUSED */
2955 static void
2956 dbuf_write_physdone(zio_t *zio, arc_buf_t *buf, void *arg)
2957 {
2958 dmu_buf_impl_t *db = arg;
2959 objset_t *os = db->db_objset;
2960 dsl_pool_t *dp = dmu_objset_pool(os);
2961 dbuf_dirty_record_t *dr;
2962 int delta = 0;
2963
2964 dr = db->db_data_pending;
2965 ASSERT3U(dr->dr_txg, ==, zio->io_txg);
2966
2967 /*
2968 * The callback will be called io_phys_children times. Retire one
2969 * portion of our dirty space each time we are called. Any rounding
2970 * error will be cleaned up by dsl_pool_sync()'s call to
2971 * dsl_pool_undirty_space().
2972 */
2973 delta = dr->dr_accounted / zio->io_phys_children;
2974 dsl_pool_undirty_space(dp, delta, zio->io_txg);
2975 }
2976
2977 /* ARGSUSED */
2978 static void
2979 dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb)
2980 {
2981 dmu_buf_impl_t *db = vdb;
2982 blkptr_t *bp_orig = &zio->io_bp_orig;
2983 blkptr_t *bp = db->db_blkptr;
2984 objset_t *os = db->db_objset;
2985 dmu_tx_t *tx = os->os_synctx;
2986 dbuf_dirty_record_t **drp, *dr;
2987
2988 ASSERT0(zio->io_error);
2989 ASSERT(db->db_blkptr == bp);
2990
2991 /*
2992 * For nopwrites and rewrites we ensure that the bp matches our
2993 * original and bypass all the accounting.
2994 */
2995 if (zio->io_flags & (ZIO_FLAG_IO_REWRITE | ZIO_FLAG_NOPWRITE)) {
2996 ASSERT(BP_EQUAL(bp, bp_orig));
2997 } else {
2998 dsl_dataset_t *ds = os->os_dsl_dataset;
2999 (void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE);
3000 dsl_dataset_block_born(ds, bp, tx);
3001 }
3002
3003 mutex_enter(&db->db_mtx);
3004
3005 DBUF_VERIFY(db);
3006
3007 drp = &db->db_last_dirty;
3008 while ((dr = *drp) != db->db_data_pending)
3009 drp = &dr->dr_next;
3010 ASSERT(!list_link_active(&dr->dr_dirty_node));
3011 ASSERT(dr->dr_dbuf == db);
3012 ASSERT(dr->dr_next == NULL);
3013 *drp = dr->dr_next;
3014
3015 #ifdef ZFS_DEBUG
3016 if (db->db_blkid == DMU_SPILL_BLKID) {
3017 dnode_t *dn;
3018
3019 DB_DNODE_ENTER(db);
3020 dn = DB_DNODE(db);
3021 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
3022 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
3023 db->db_blkptr == &dn->dn_phys->dn_spill);
3024 DB_DNODE_EXIT(db);
3025 }
3026 #endif
3027
3028 if (db->db_level == 0) {
3029 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
3030 ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
3031 if (db->db_state != DB_NOFILL) {
3032 if (dr->dt.dl.dr_data != db->db_buf)
3033 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data,
3034 db));
3035 else if (!arc_released(db->db_buf))
3036 arc_set_callback(db->db_buf, dbuf_do_evict, db);
3037 }
3038 } else {
3039 dnode_t *dn;
3040
3041 DB_DNODE_ENTER(db);
3042 dn = DB_DNODE(db);
3043 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
3044 ASSERT3U(db->db.db_size, ==, 1 << dn->dn_phys->dn_indblkshift);
3045 if (!BP_IS_HOLE(db->db_blkptr)) {
3046 int epbs =
3047 dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
3048 ASSERT3U(db->db_blkid, <=,
3049 dn->dn_phys->dn_maxblkid >> (db->db_level * epbs));
3050 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==,
3051 db->db.db_size);
3052 if (!arc_released(db->db_buf))
3053 arc_set_callback(db->db_buf, dbuf_do_evict, db);
3054 }
3055 DB_DNODE_EXIT(db);
3056 mutex_destroy(&dr->dt.di.dr_mtx);
3057 list_destroy(&dr->dt.di.dr_children);
3058 }
3059 kmem_free(dr, sizeof (dbuf_dirty_record_t));
3060
3061 cv_broadcast(&db->db_changed);
3062 ASSERT(db->db_dirtycnt > 0);
3063 db->db_dirtycnt -= 1;
3064 db->db_data_pending = NULL;
3065 dbuf_rele_and_unlock(db, (void *)(uintptr_t)tx->tx_txg);
3066 }
3067
3068 static void
3069 dbuf_write_nofill_ready(zio_t *zio)
3070 {
3071 dbuf_write_ready(zio, NULL, zio->io_private);
3072 }
3073
3074 static void
3075 dbuf_write_nofill_done(zio_t *zio)
3076 {
3077 dbuf_write_done(zio, NULL, zio->io_private);
3078 }
3079
3080 static void
3081 dbuf_write_override_ready(zio_t *zio)
3082 {
3083 dbuf_dirty_record_t *dr = zio->io_private;
3084 dmu_buf_impl_t *db = dr->dr_dbuf;
3085
3086 dbuf_write_ready(zio, NULL, db);
3087 }
3088
3089 static void
3090 dbuf_write_override_done(zio_t *zio)
3091 {
3092 dbuf_dirty_record_t *dr = zio->io_private;
3093 dmu_buf_impl_t *db = dr->dr_dbuf;
3094 blkptr_t *obp = &dr->dt.dl.dr_overridden_by;
3095
3096 mutex_enter(&db->db_mtx);
3097 if (!BP_EQUAL(zio->io_bp, obp)) {
3098 if (!BP_IS_HOLE(obp))
3099 dsl_free(spa_get_dsl(zio->io_spa), zio->io_txg, obp);
3100 arc_release(dr->dt.dl.dr_data, db);
3101 }
3102 mutex_exit(&db->db_mtx);
3103
3104 dbuf_write_done(zio, NULL, db);
3105 }
3106
3107 /* Issue I/O to commit a dirty buffer to disk. */
3108 static void
3109 dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx)
3110 {
3111 dmu_buf_impl_t *db = dr->dr_dbuf;
3112 dnode_t *dn;
3113 objset_t *os;
3114 dmu_buf_impl_t *parent = db->db_parent;
3115 uint64_t txg = tx->tx_txg;
3116 zbookmark_phys_t zb;
3117 zio_prop_t zp;
3118 zio_t *zio;
3119 int wp_flag = 0;
3120
3121 DB_DNODE_ENTER(db);
3122 dn = DB_DNODE(db);
3123 os = dn->dn_objset;
3124
3125 if (db->db_state != DB_NOFILL) {
3126 if (db->db_level > 0 || dn->dn_type == DMU_OT_DNODE) {
3127 /*
3128 * Private object buffers are released here rather
3129 * than in dbuf_dirty() since they are only modified
3130 * in the syncing context and we don't want the
3131 * overhead of making multiple copies of the data.
3132 */
3133 if (BP_IS_HOLE(db->db_blkptr)) {
3134 arc_buf_thaw(data);
3135 } else {
3136 dbuf_release_bp(db);
3137 }
3138 }
3139 }
3140
3141 if (parent != dn->dn_dbuf) {
3142 /* Our parent is an indirect block. */
3143 /* We have a dirty parent that has been scheduled for write. */
3144 ASSERT(parent && parent->db_data_pending);
3145 /* Our parent's buffer is one level closer to the dnode. */
3146 ASSERT(db->db_level == parent->db_level-1);
3147 /*
3148 * We're about to modify our parent's db_data by modifying
3149 * our block pointer, so the parent must be released.
3150 */
3151 ASSERT(arc_released(parent->db_buf));
3152 zio = parent->db_data_pending->dr_zio;
3153 } else {
3154 /* Our parent is the dnode itself. */
3155 ASSERT((db->db_level == dn->dn_phys->dn_nlevels-1 &&
3156 db->db_blkid != DMU_SPILL_BLKID) ||
3157 (db->db_blkid == DMU_SPILL_BLKID && db->db_level == 0));
3158 if (db->db_blkid != DMU_SPILL_BLKID)
3159 ASSERT3P(db->db_blkptr, ==,
3160 &dn->dn_phys->dn_blkptr[db->db_blkid]);
3161 zio = dn->dn_zio;
3162 }
3163
3164 ASSERT(db->db_level == 0 || data == db->db_buf);
3165 ASSERT3U(db->db_blkptr->blk_birth, <=, txg);
3166 ASSERT(zio);
3167
3168 SET_BOOKMARK(&zb, os->os_dsl_dataset ?
3169 os->os_dsl_dataset->ds_object : DMU_META_OBJSET,
3170 db->db.db_object, db->db_level, db->db_blkid);
3171
3172 if (db->db_blkid == DMU_SPILL_BLKID)
3173 wp_flag = WP_SPILL;
3174 wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0;
3175
3176 dmu_write_policy(os, dn, db->db_level, wp_flag, &zp);
3177 DB_DNODE_EXIT(db);
3178
3179 if (db->db_level == 0 &&
3180 dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
3181 /*
3182 * The BP for this block has been provided by open context
3183 * (by dmu_sync() or dmu_buf_write_embedded()).
3184 */
3185 void *contents = (data != NULL) ? data->b_data : NULL;
3186
3187 dr->dr_zio = zio_write(zio, os->os_spa, txg,
3188 db->db_blkptr, contents, db->db.db_size, &zp,
3189 dbuf_write_override_ready, NULL, dbuf_write_override_done,
3190 dr, ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
3191 mutex_enter(&db->db_mtx);
3192 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
3193 zio_write_override(dr->dr_zio, &dr->dt.dl.dr_overridden_by,
3194 dr->dt.dl.dr_copies, dr->dt.dl.dr_nopwrite);
3195 mutex_exit(&db->db_mtx);
3196 } else if (db->db_state == DB_NOFILL) {
3197 ASSERT(zp.zp_checksum == ZIO_CHECKSUM_OFF ||
3198 zp.zp_checksum == ZIO_CHECKSUM_NOPARITY);
3199 dr->dr_zio = zio_write(zio, os->os_spa, txg,
3200 db->db_blkptr, NULL, db->db.db_size, &zp,
3201 dbuf_write_nofill_ready, NULL, dbuf_write_nofill_done, db,
3202 ZIO_PRIORITY_ASYNC_WRITE,
3203 ZIO_FLAG_MUSTSUCCEED | ZIO_FLAG_NODATA, &zb);
3204 } else {
3205 ASSERT(arc_released(data));
3206 dr->dr_zio = arc_write(zio, os->os_spa, txg,
3207 db->db_blkptr, data, DBUF_IS_L2CACHEABLE(db),
3208 DBUF_IS_L2COMPRESSIBLE(db), &zp, dbuf_write_ready,
3209 dbuf_write_physdone, dbuf_write_done, db,
3210 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
3211 }
3212 }