1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
24 * Copyright (c) 2013 by Delphix. All rights reserved.
25 * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
26 * Copyright (c) 2013, Joyent, Inc. All rights reserved.
27 */
28
29 #include <sys/zfs_context.h>
30 #include <sys/dmu.h>
31 #include <sys/dmu_send.h>
32 #include <sys/dmu_impl.h>
33 #include <sys/dbuf.h>
34 #include <sys/dmu_objset.h>
35 #include <sys/dsl_dataset.h>
36 #include <sys/dsl_dir.h>
37 #include <sys/dmu_tx.h>
38 #include <sys/spa.h>
39 #include <sys/zio.h>
40 #include <sys/dmu_zfetch.h>
41 #include <sys/sa.h>
42 #include <sys/sa_impl.h>
43
44 /*
45 * Number of times that zfs_free_range() took the slow path while doing
46 * a zfs receive. A nonzero value indicates a potential performance problem.
47 */
48 uint64_t zfs_free_range_recv_miss;
49
50 static void dbuf_destroy(dmu_buf_impl_t *db);
51 static boolean_t dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
52 static void dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx);
53
54 /*
55 * Global data structures and functions for the dbuf cache.
56 */
57 static kmem_cache_t *dbuf_cache;
58
59 /* ARGSUSED */
60 static int
61 dbuf_cons(void *vdb, void *unused, int kmflag)
62 {
63 dmu_buf_impl_t *db = vdb;
64 bzero(db, sizeof (dmu_buf_impl_t));
65
66 mutex_init(&db->db_mtx, NULL, MUTEX_DEFAULT, NULL);
67 cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL);
68 refcount_create(&db->db_holds);
69 return (0);
70 }
71
72 /* ARGSUSED */
73 static void
74 dbuf_dest(void *vdb, void *unused)
75 {
76 dmu_buf_impl_t *db = vdb;
77 mutex_destroy(&db->db_mtx);
78 cv_destroy(&db->db_changed);
79 refcount_destroy(&db->db_holds);
80 }
81
82 /*
83 * dbuf hash table routines
84 */
85 static dbuf_hash_table_t dbuf_hash_table;
86
87 static uint64_t dbuf_hash_count;
88
89 static uint64_t
90 dbuf_hash(void *os, uint64_t obj, uint8_t lvl, uint64_t blkid)
91 {
92 uintptr_t osv = (uintptr_t)os;
93 uint64_t crc = -1ULL;
94
95 ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY);
96 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (lvl)) & 0xFF];
97 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (osv >> 6)) & 0xFF];
98 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 0)) & 0xFF];
99 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 8)) & 0xFF];
100 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 0)) & 0xFF];
101 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 8)) & 0xFF];
102
103 crc ^= (osv>>14) ^ (obj>>16) ^ (blkid>>16);
104
105 return (crc);
106 }
107
108 #define DBUF_HASH(os, obj, level, blkid) dbuf_hash(os, obj, level, blkid);
109
110 #define DBUF_EQUAL(dbuf, os, obj, level, blkid) \
111 ((dbuf)->db.db_object == (obj) && \
112 (dbuf)->db_objset == (os) && \
113 (dbuf)->db_level == (level) && \
114 (dbuf)->db_blkid == (blkid))
115
116 dmu_buf_impl_t *
117 dbuf_find(dnode_t *dn, uint8_t level, uint64_t blkid)
118 {
119 dbuf_hash_table_t *h = &dbuf_hash_table;
120 objset_t *os = dn->dn_objset;
121 uint64_t obj = dn->dn_object;
122 uint64_t hv = DBUF_HASH(os, obj, level, blkid);
123 uint64_t idx = hv & h->hash_table_mask;
124 dmu_buf_impl_t *db;
125
126 mutex_enter(DBUF_HASH_MUTEX(h, idx));
127 for (db = h->hash_table[idx]; db != NULL; db = db->db_hash_next) {
128 if (DBUF_EQUAL(db, os, obj, level, blkid)) {
129 mutex_enter(&db->db_mtx);
130 if (db->db_state != DB_EVICTING) {
131 mutex_exit(DBUF_HASH_MUTEX(h, idx));
132 return (db);
133 }
134 mutex_exit(&db->db_mtx);
135 }
136 }
137 mutex_exit(DBUF_HASH_MUTEX(h, idx));
138 return (NULL);
139 }
140
141 /*
142 * Insert an entry into the hash table. If there is already an element
143 * equal to elem in the hash table, then the already existing element
144 * will be returned and the new element will not be inserted.
145 * Otherwise returns NULL.
146 */
147 static dmu_buf_impl_t *
148 dbuf_hash_insert(dmu_buf_impl_t *db)
149 {
150 dbuf_hash_table_t *h = &dbuf_hash_table;
151 objset_t *os = db->db_objset;
152 uint64_t obj = db->db.db_object;
153 int level = db->db_level;
154 uint64_t blkid = db->db_blkid;
155 uint64_t hv = DBUF_HASH(os, obj, level, blkid);
156 uint64_t idx = hv & h->hash_table_mask;
157 dmu_buf_impl_t *dbf;
158
159 mutex_enter(DBUF_HASH_MUTEX(h, idx));
160 for (dbf = h->hash_table[idx]; dbf != NULL; dbf = dbf->db_hash_next) {
161 if (DBUF_EQUAL(dbf, os, obj, level, blkid)) {
162 mutex_enter(&dbf->db_mtx);
163 if (dbf->db_state != DB_EVICTING) {
164 mutex_exit(DBUF_HASH_MUTEX(h, idx));
165 return (dbf);
166 }
167 mutex_exit(&dbf->db_mtx);
168 }
169 }
170
171 mutex_enter(&db->db_mtx);
172 db->db_hash_next = h->hash_table[idx];
173 h->hash_table[idx] = db;
174 mutex_exit(DBUF_HASH_MUTEX(h, idx));
175 atomic_add_64(&dbuf_hash_count, 1);
176
177 return (NULL);
178 }
179
180 /*
181 * Remove an entry from the hash table. This operation will
182 * fail if there are any existing holds on the db.
183 */
184 static void
185 dbuf_hash_remove(dmu_buf_impl_t *db)
186 {
187 dbuf_hash_table_t *h = &dbuf_hash_table;
188 uint64_t hv = DBUF_HASH(db->db_objset, db->db.db_object,
189 db->db_level, db->db_blkid);
190 uint64_t idx = hv & h->hash_table_mask;
191 dmu_buf_impl_t *dbf, **dbp;
192
193 /*
194 * We musn't hold db_mtx to maintin lock ordering:
195 * DBUF_HASH_MUTEX > db_mtx.
196 */
197 ASSERT(refcount_is_zero(&db->db_holds));
198 ASSERT(db->db_state == DB_EVICTING);
199 ASSERT(!MUTEX_HELD(&db->db_mtx));
200
201 mutex_enter(DBUF_HASH_MUTEX(h, idx));
202 dbp = &h->hash_table[idx];
203 while ((dbf = *dbp) != db) {
204 dbp = &dbf->db_hash_next;
205 ASSERT(dbf != NULL);
206 }
207 *dbp = db->db_hash_next;
208 db->db_hash_next = NULL;
209 mutex_exit(DBUF_HASH_MUTEX(h, idx));
210 atomic_add_64(&dbuf_hash_count, -1);
211 }
212
213 static arc_evict_func_t dbuf_do_evict;
214
215 static void
216 dbuf_evict_user(dmu_buf_impl_t *db)
217 {
218 ASSERT(MUTEX_HELD(&db->db_mtx));
219
220 if (db->db_level != 0 || db->db_evict_func == NULL)
221 return;
222
223 if (db->db_user_data_ptr_ptr)
224 *db->db_user_data_ptr_ptr = db->db.db_data;
225 db->db_evict_func(&db->db, db->db_user_ptr);
226 db->db_user_ptr = NULL;
227 db->db_user_data_ptr_ptr = NULL;
228 db->db_evict_func = NULL;
229 }
230
231 boolean_t
232 dbuf_is_metadata(dmu_buf_impl_t *db)
233 {
234 if (db->db_level > 0) {
235 return (B_TRUE);
236 } else {
237 boolean_t is_metadata;
238
239 DB_DNODE_ENTER(db);
240 is_metadata = DMU_OT_IS_METADATA(DB_DNODE(db)->dn_type);
241 DB_DNODE_EXIT(db);
242
243 return (is_metadata);
244 }
245 }
246
247 void
248 dbuf_evict(dmu_buf_impl_t *db)
249 {
250 ASSERT(MUTEX_HELD(&db->db_mtx));
251 ASSERT(db->db_buf == NULL);
252 ASSERT(db->db_data_pending == NULL);
253
254 dbuf_clear(db);
255 dbuf_destroy(db);
256 }
257
258 void
259 dbuf_init(void)
260 {
261 uint64_t hsize = 1ULL << 16;
262 dbuf_hash_table_t *h = &dbuf_hash_table;
263 int i;
264
265 /*
266 * The hash table is big enough to fill all of physical memory
267 * with an average 4K block size. The table will take up
268 * totalmem*sizeof(void*)/4K (i.e. 2MB/GB with 8-byte pointers).
269 */
270 while (hsize * 4096 < physmem * PAGESIZE)
271 hsize <<= 1;
272
273 retry:
274 h->hash_table_mask = hsize - 1;
275 h->hash_table = kmem_zalloc(hsize * sizeof (void *), KM_NOSLEEP);
276 if (h->hash_table == NULL) {
277 /* XXX - we should really return an error instead of assert */
278 ASSERT(hsize > (1ULL << 10));
279 hsize >>= 1;
280 goto retry;
281 }
282
283 dbuf_cache = kmem_cache_create("dmu_buf_impl_t",
284 sizeof (dmu_buf_impl_t),
285 0, dbuf_cons, dbuf_dest, NULL, NULL, NULL, 0);
286
287 for (i = 0; i < DBUF_MUTEXES; i++)
288 mutex_init(&h->hash_mutexes[i], NULL, MUTEX_DEFAULT, NULL);
289 }
290
291 void
292 dbuf_fini(void)
293 {
294 dbuf_hash_table_t *h = &dbuf_hash_table;
295 int i;
296
297 for (i = 0; i < DBUF_MUTEXES; i++)
298 mutex_destroy(&h->hash_mutexes[i]);
299 kmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *));
300 kmem_cache_destroy(dbuf_cache);
301 }
302
303 /*
304 * Other stuff.
305 */
306
307 #ifdef ZFS_DEBUG
308 static void
309 dbuf_verify(dmu_buf_impl_t *db)
310 {
311 dnode_t *dn;
312 dbuf_dirty_record_t *dr;
313
314 ASSERT(MUTEX_HELD(&db->db_mtx));
315
316 if (!(zfs_flags & ZFS_DEBUG_DBUF_VERIFY))
317 return;
318
319 ASSERT(db->db_objset != NULL);
320 DB_DNODE_ENTER(db);
321 dn = DB_DNODE(db);
322 if (dn == NULL) {
323 ASSERT(db->db_parent == NULL);
324 ASSERT(db->db_blkptr == NULL);
325 } else {
326 ASSERT3U(db->db.db_object, ==, dn->dn_object);
327 ASSERT3P(db->db_objset, ==, dn->dn_objset);
328 ASSERT3U(db->db_level, <, dn->dn_nlevels);
329 ASSERT(db->db_blkid == DMU_BONUS_BLKID ||
330 db->db_blkid == DMU_SPILL_BLKID ||
331 !list_is_empty(&dn->dn_dbufs));
332 }
333 if (db->db_blkid == DMU_BONUS_BLKID) {
334 ASSERT(dn != NULL);
335 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
336 ASSERT3U(db->db.db_offset, ==, DMU_BONUS_BLKID);
337 } else if (db->db_blkid == DMU_SPILL_BLKID) {
338 ASSERT(dn != NULL);
339 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
340 ASSERT0(db->db.db_offset);
341 } else {
342 ASSERT3U(db->db.db_offset, ==, db->db_blkid * db->db.db_size);
343 }
344
345 for (dr = db->db_data_pending; dr != NULL; dr = dr->dr_next)
346 ASSERT(dr->dr_dbuf == db);
347
348 for (dr = db->db_last_dirty; dr != NULL; dr = dr->dr_next)
349 ASSERT(dr->dr_dbuf == db);
350
351 /*
352 * We can't assert that db_size matches dn_datablksz because it
353 * can be momentarily different when another thread is doing
354 * dnode_set_blksz().
355 */
356 if (db->db_level == 0 && db->db.db_object == DMU_META_DNODE_OBJECT) {
357 dr = db->db_data_pending;
358 /*
359 * It should only be modified in syncing context, so
360 * make sure we only have one copy of the data.
361 */
362 ASSERT(dr == NULL || dr->dt.dl.dr_data == db->db_buf);
363 }
364
365 /* verify db->db_blkptr */
366 if (db->db_blkptr) {
367 if (db->db_parent == dn->dn_dbuf) {
368 /* db is pointed to by the dnode */
369 /* ASSERT3U(db->db_blkid, <, dn->dn_nblkptr); */
370 if (DMU_OBJECT_IS_SPECIAL(db->db.db_object))
371 ASSERT(db->db_parent == NULL);
372 else
373 ASSERT(db->db_parent != NULL);
374 if (db->db_blkid != DMU_SPILL_BLKID)
375 ASSERT3P(db->db_blkptr, ==,
376 &dn->dn_phys->dn_blkptr[db->db_blkid]);
377 } else {
378 /* db is pointed to by an indirect block */
379 int epb = db->db_parent->db.db_size >> SPA_BLKPTRSHIFT;
380 ASSERT3U(db->db_parent->db_level, ==, db->db_level+1);
381 ASSERT3U(db->db_parent->db.db_object, ==,
382 db->db.db_object);
383 /*
384 * dnode_grow_indblksz() can make this fail if we don't
385 * have the struct_rwlock. XXX indblksz no longer
386 * grows. safe to do this now?
387 */
388 if (RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
389 ASSERT3P(db->db_blkptr, ==,
390 ((blkptr_t *)db->db_parent->db.db_data +
391 db->db_blkid % epb));
392 }
393 }
394 }
395 if ((db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr)) &&
396 (db->db_buf == NULL || db->db_buf->b_data) &&
397 db->db.db_data && db->db_blkid != DMU_BONUS_BLKID &&
398 db->db_state != DB_FILL && !dn->dn_free_txg) {
399 /*
400 * If the blkptr isn't set but they have nonzero data,
401 * it had better be dirty, otherwise we'll lose that
402 * data when we evict this buffer.
403 */
404 if (db->db_dirtycnt == 0) {
405 uint64_t *buf = db->db.db_data;
406 int i;
407
408 for (i = 0; i < db->db.db_size >> 3; i++) {
409 ASSERT(buf[i] == 0);
410 }
411 }
412 }
413 DB_DNODE_EXIT(db);
414 }
415 #endif
416
417 static void
418 dbuf_update_data(dmu_buf_impl_t *db)
419 {
420 ASSERT(MUTEX_HELD(&db->db_mtx));
421 if (db->db_level == 0 && db->db_user_data_ptr_ptr) {
422 ASSERT(!refcount_is_zero(&db->db_holds));
423 *db->db_user_data_ptr_ptr = db->db.db_data;
424 }
425 }
426
427 static void
428 dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf)
429 {
430 ASSERT(MUTEX_HELD(&db->db_mtx));
431 ASSERT(db->db_buf == NULL || !arc_has_callback(db->db_buf));
432 db->db_buf = buf;
433 if (buf != NULL) {
434 ASSERT(buf->b_data != NULL);
435 db->db.db_data = buf->b_data;
436 if (!arc_released(buf))
437 arc_set_callback(buf, dbuf_do_evict, db);
438 dbuf_update_data(db);
439 } else {
440 dbuf_evict_user(db);
441 db->db.db_data = NULL;
442 if (db->db_state != DB_NOFILL)
443 db->db_state = DB_UNCACHED;
444 }
445 }
446
447 /*
448 * Loan out an arc_buf for read. Return the loaned arc_buf.
449 */
450 arc_buf_t *
451 dbuf_loan_arcbuf(dmu_buf_impl_t *db)
452 {
453 arc_buf_t *abuf;
454
455 mutex_enter(&db->db_mtx);
456 if (arc_released(db->db_buf) || refcount_count(&db->db_holds) > 1) {
457 int blksz = db->db.db_size;
458 spa_t *spa = db->db_objset->os_spa;
459
460 mutex_exit(&db->db_mtx);
461 abuf = arc_loan_buf(spa, blksz);
462 bcopy(db->db.db_data, abuf->b_data, blksz);
463 } else {
464 abuf = db->db_buf;
465 arc_loan_inuse_buf(abuf, db);
466 dbuf_set_data(db, NULL);
467 mutex_exit(&db->db_mtx);
468 }
469 return (abuf);
470 }
471
472 uint64_t
473 dbuf_whichblock(dnode_t *dn, uint64_t offset)
474 {
475 if (dn->dn_datablkshift) {
476 return (offset >> dn->dn_datablkshift);
477 } else {
478 ASSERT3U(offset, <, dn->dn_datablksz);
479 return (0);
480 }
481 }
482
483 static void
484 dbuf_read_done(zio_t *zio, arc_buf_t *buf, void *vdb)
485 {
486 dmu_buf_impl_t *db = vdb;
487
488 mutex_enter(&db->db_mtx);
489 ASSERT3U(db->db_state, ==, DB_READ);
490 /*
491 * All reads are synchronous, so we must have a hold on the dbuf
492 */
493 ASSERT(refcount_count(&db->db_holds) > 0);
494 ASSERT(db->db_buf == NULL);
495 ASSERT(db->db.db_data == NULL);
496 if (db->db_level == 0 && db->db_freed_in_flight) {
497 /* we were freed in flight; disregard any error */
498 arc_release(buf, db);
499 bzero(buf->b_data, db->db.db_size);
500 arc_buf_freeze(buf);
501 db->db_freed_in_flight = FALSE;
502 dbuf_set_data(db, buf);
503 db->db_state = DB_CACHED;
504 } else if (zio == NULL || zio->io_error == 0) {
505 dbuf_set_data(db, buf);
506 db->db_state = DB_CACHED;
507 } else {
508 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
509 ASSERT3P(db->db_buf, ==, NULL);
510 VERIFY(arc_buf_remove_ref(buf, db));
511 db->db_state = DB_UNCACHED;
512 }
513 cv_broadcast(&db->db_changed);
514 dbuf_rele_and_unlock(db, NULL);
515 }
516
517 static void
518 dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t *flags)
519 {
520 dnode_t *dn;
521 zbookmark_t zb;
522 uint32_t aflags = ARC_NOWAIT;
523
524 DB_DNODE_ENTER(db);
525 dn = DB_DNODE(db);
526 ASSERT(!refcount_is_zero(&db->db_holds));
527 /* We need the struct_rwlock to prevent db_blkptr from changing. */
528 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
529 ASSERT(MUTEX_HELD(&db->db_mtx));
530 ASSERT(db->db_state == DB_UNCACHED);
531 ASSERT(db->db_buf == NULL);
532
533 if (db->db_blkid == DMU_BONUS_BLKID) {
534 int bonuslen = MIN(dn->dn_bonuslen, dn->dn_phys->dn_bonuslen);
535
536 ASSERT3U(bonuslen, <=, db->db.db_size);
537 db->db.db_data = zio_buf_alloc(DN_MAX_BONUSLEN);
538 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
539 if (bonuslen < DN_MAX_BONUSLEN)
540 bzero(db->db.db_data, DN_MAX_BONUSLEN);
541 if (bonuslen)
542 bcopy(DN_BONUS(dn->dn_phys), db->db.db_data, bonuslen);
543 DB_DNODE_EXIT(db);
544 dbuf_update_data(db);
545 db->db_state = DB_CACHED;
546 mutex_exit(&db->db_mtx);
547 return;
548 }
549
550 /*
551 * Recheck BP_IS_HOLE() after dnode_block_freed() in case dnode_sync()
552 * processes the delete record and clears the bp while we are waiting
553 * for the dn_mtx (resulting in a "no" from block_freed).
554 */
555 if (db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr) ||
556 (db->db_level == 0 && (dnode_block_freed(dn, db->db_blkid) ||
557 BP_IS_HOLE(db->db_blkptr)))) {
558 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
559
560 DB_DNODE_EXIT(db);
561 dbuf_set_data(db, arc_buf_alloc(db->db_objset->os_spa,
562 db->db.db_size, db, type));
563 bzero(db->db.db_data, db->db.db_size);
564 db->db_state = DB_CACHED;
565 *flags |= DB_RF_CACHED;
566 mutex_exit(&db->db_mtx);
567 return;
568 }
569
570 DB_DNODE_EXIT(db);
571
572 db->db_state = DB_READ;
573 mutex_exit(&db->db_mtx);
574
575 if (DBUF_IS_L2CACHEABLE(db))
576 aflags |= ARC_L2CACHE;
577 if (DBUF_IS_L2COMPRESSIBLE(db))
578 aflags |= ARC_L2COMPRESS;
579
580 SET_BOOKMARK(&zb, db->db_objset->os_dsl_dataset ?
581 db->db_objset->os_dsl_dataset->ds_object : DMU_META_OBJSET,
582 db->db.db_object, db->db_level, db->db_blkid);
583
584 dbuf_add_ref(db, NULL);
585
586 (void) arc_read(zio, db->db_objset->os_spa, db->db_blkptr,
587 dbuf_read_done, db, ZIO_PRIORITY_SYNC_READ,
588 (*flags & DB_RF_CANFAIL) ? ZIO_FLAG_CANFAIL : ZIO_FLAG_MUSTSUCCEED,
589 &aflags, &zb);
590 if (aflags & ARC_CACHED)
591 *flags |= DB_RF_CACHED;
592 }
593
594 int
595 dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
596 {
597 int err = 0;
598 boolean_t havepzio = (zio != NULL);
599 boolean_t prefetch;
600 dnode_t *dn;
601
602 /*
603 * We don't have to hold the mutex to check db_state because it
604 * can't be freed while we have a hold on the buffer.
605 */
606 ASSERT(!refcount_is_zero(&db->db_holds));
607
608 if (db->db_state == DB_NOFILL)
609 return (SET_ERROR(EIO));
610
611 DB_DNODE_ENTER(db);
612 dn = DB_DNODE(db);
613 if ((flags & DB_RF_HAVESTRUCT) == 0)
614 rw_enter(&dn->dn_struct_rwlock, RW_READER);
615
616 prefetch = db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
617 (flags & DB_RF_NOPREFETCH) == 0 && dn != NULL &&
618 DBUF_IS_CACHEABLE(db);
619
620 mutex_enter(&db->db_mtx);
621 if (db->db_state == DB_CACHED) {
622 mutex_exit(&db->db_mtx);
623 if (prefetch)
624 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset,
625 db->db.db_size, TRUE);
626 if ((flags & DB_RF_HAVESTRUCT) == 0)
627 rw_exit(&dn->dn_struct_rwlock);
628 DB_DNODE_EXIT(db);
629 } else if (db->db_state == DB_UNCACHED) {
630 spa_t *spa = dn->dn_objset->os_spa;
631
632 if (zio == NULL)
633 zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL);
634 dbuf_read_impl(db, zio, &flags);
635
636 /* dbuf_read_impl has dropped db_mtx for us */
637
638 if (prefetch)
639 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset,
640 db->db.db_size, flags & DB_RF_CACHED);
641
642 if ((flags & DB_RF_HAVESTRUCT) == 0)
643 rw_exit(&dn->dn_struct_rwlock);
644 DB_DNODE_EXIT(db);
645
646 if (!havepzio)
647 err = zio_wait(zio);
648 } else {
649 /*
650 * Another reader came in while the dbuf was in flight
651 * between UNCACHED and CACHED. Either a writer will finish
652 * writing the buffer (sending the dbuf to CACHED) or the
653 * first reader's request will reach the read_done callback
654 * and send the dbuf to CACHED. Otherwise, a failure
655 * occurred and the dbuf went to UNCACHED.
656 */
657 mutex_exit(&db->db_mtx);
658 if (prefetch)
659 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset,
660 db->db.db_size, TRUE);
661 if ((flags & DB_RF_HAVESTRUCT) == 0)
662 rw_exit(&dn->dn_struct_rwlock);
663 DB_DNODE_EXIT(db);
664
665 /* Skip the wait per the caller's request. */
666 mutex_enter(&db->db_mtx);
667 if ((flags & DB_RF_NEVERWAIT) == 0) {
668 while (db->db_state == DB_READ ||
669 db->db_state == DB_FILL) {
670 ASSERT(db->db_state == DB_READ ||
671 (flags & DB_RF_HAVESTRUCT) == 0);
672 cv_wait(&db->db_changed, &db->db_mtx);
673 }
674 if (db->db_state == DB_UNCACHED)
675 err = SET_ERROR(EIO);
676 }
677 mutex_exit(&db->db_mtx);
678 }
679
680 ASSERT(err || havepzio || db->db_state == DB_CACHED);
681 return (err);
682 }
683
684 static void
685 dbuf_noread(dmu_buf_impl_t *db)
686 {
687 ASSERT(!refcount_is_zero(&db->db_holds));
688 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
689 mutex_enter(&db->db_mtx);
690 while (db->db_state == DB_READ || db->db_state == DB_FILL)
691 cv_wait(&db->db_changed, &db->db_mtx);
692 if (db->db_state == DB_UNCACHED) {
693 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
694 spa_t *spa = db->db_objset->os_spa;
695
696 ASSERT(db->db_buf == NULL);
697 ASSERT(db->db.db_data == NULL);
698 dbuf_set_data(db, arc_buf_alloc(spa, db->db.db_size, db, type));
699 db->db_state = DB_FILL;
700 } else if (db->db_state == DB_NOFILL) {
701 dbuf_set_data(db, NULL);
702 } else {
703 ASSERT3U(db->db_state, ==, DB_CACHED);
704 }
705 mutex_exit(&db->db_mtx);
706 }
707
708 /*
709 * This is our just-in-time copy function. It makes a copy of
710 * buffers, that have been modified in a previous transaction
711 * group, before we modify them in the current active group.
712 *
713 * This function is used in two places: when we are dirtying a
714 * buffer for the first time in a txg, and when we are freeing
715 * a range in a dnode that includes this buffer.
716 *
717 * Note that when we are called from dbuf_free_range() we do
718 * not put a hold on the buffer, we just traverse the active
719 * dbuf list for the dnode.
720 */
721 static void
722 dbuf_fix_old_data(dmu_buf_impl_t *db, uint64_t txg)
723 {
724 dbuf_dirty_record_t *dr = db->db_last_dirty;
725
726 ASSERT(MUTEX_HELD(&db->db_mtx));
727 ASSERT(db->db.db_data != NULL);
728 ASSERT(db->db_level == 0);
729 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT);
730
731 if (dr == NULL ||
732 (dr->dt.dl.dr_data !=
733 ((db->db_blkid == DMU_BONUS_BLKID) ? db->db.db_data : db->db_buf)))
734 return;
735
736 /*
737 * If the last dirty record for this dbuf has not yet synced
738 * and its referencing the dbuf data, either:
739 * reset the reference to point to a new copy,
740 * or (if there a no active holders)
741 * just null out the current db_data pointer.
742 */
743 ASSERT(dr->dr_txg >= txg - 2);
744 if (db->db_blkid == DMU_BONUS_BLKID) {
745 /* Note that the data bufs here are zio_bufs */
746 dr->dt.dl.dr_data = zio_buf_alloc(DN_MAX_BONUSLEN);
747 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
748 bcopy(db->db.db_data, dr->dt.dl.dr_data, DN_MAX_BONUSLEN);
749 } else if (refcount_count(&db->db_holds) > db->db_dirtycnt) {
750 int size = db->db.db_size;
751 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
752 spa_t *spa = db->db_objset->os_spa;
753
754 dr->dt.dl.dr_data = arc_buf_alloc(spa, size, db, type);
755 bcopy(db->db.db_data, dr->dt.dl.dr_data->b_data, size);
756 } else {
757 dbuf_set_data(db, NULL);
758 }
759 }
760
761 void
762 dbuf_unoverride(dbuf_dirty_record_t *dr)
763 {
764 dmu_buf_impl_t *db = dr->dr_dbuf;
765 blkptr_t *bp = &dr->dt.dl.dr_overridden_by;
766 uint64_t txg = dr->dr_txg;
767
768 ASSERT(MUTEX_HELD(&db->db_mtx));
769 ASSERT(dr->dt.dl.dr_override_state != DR_IN_DMU_SYNC);
770 ASSERT(db->db_level == 0);
771
772 if (db->db_blkid == DMU_BONUS_BLKID ||
773 dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN)
774 return;
775
776 ASSERT(db->db_data_pending != dr);
777
778 /* free this block */
779 if (!BP_IS_HOLE(bp) && !dr->dt.dl.dr_nopwrite)
780 zio_free(db->db_objset->os_spa, txg, bp);
781
782 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
783 dr->dt.dl.dr_nopwrite = B_FALSE;
784
785 /*
786 * Release the already-written buffer, so we leave it in
787 * a consistent dirty state. Note that all callers are
788 * modifying the buffer, so they will immediately do
789 * another (redundant) arc_release(). Therefore, leave
790 * the buf thawed to save the effort of freezing &
791 * immediately re-thawing it.
792 */
793 arc_release(dr->dt.dl.dr_data, db);
794 }
795
796 /*
797 * Evict (if its unreferenced) or clear (if its referenced) any level-0
798 * data blocks in the free range, so that any future readers will find
799 * empty blocks.
800 *
801 * This is a no-op if the dataset is in the middle of an incremental
802 * receive; see comment below for details.
803 */
804 void
805 dbuf_free_range(dnode_t *dn, uint64_t start, uint64_t end, dmu_tx_t *tx)
806 {
807 dmu_buf_impl_t *db, *db_next;
808 uint64_t txg = tx->tx_txg;
809
810 if (end > dn->dn_maxblkid && (end != DMU_SPILL_BLKID))
811 end = dn->dn_maxblkid;
812 dprintf_dnode(dn, "start=%llu end=%llu\n", start, end);
813
814 mutex_enter(&dn->dn_dbufs_mtx);
815 if (start >= dn->dn_unlisted_l0_blkid * dn->dn_datablksz) {
816 /* There can't be any dbufs in this range; no need to search. */
817 mutex_exit(&dn->dn_dbufs_mtx);
818 return;
819 } else if (dmu_objset_is_receiving(dn->dn_objset)) {
820 /*
821 * If we are receiving, we expect there to be no dbufs in
822 * the range to be freed, because receive modifies each
823 * block at most once, and in offset order. If this is
824 * not the case, it can lead to performance problems,
825 * so note that we unexpectedly took the slow path.
826 */
827 atomic_inc_64(&zfs_free_range_recv_miss);
828 }
829
830 for (db = list_head(&dn->dn_dbufs); db != NULL; db = db_next) {
831 db_next = list_next(&dn->dn_dbufs, db);
832 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
833
834 if (db->db_level != 0)
835 continue;
836 if (db->db_blkid < start || db->db_blkid > end)
837 continue;
838
839 /* found a level 0 buffer in the range */
840 mutex_enter(&db->db_mtx);
841 if (dbuf_undirty(db, tx)) {
842 /* mutex has been dropped and dbuf destroyed */
843 continue;
844 }
845
846 if (db->db_state == DB_UNCACHED ||
847 db->db_state == DB_NOFILL ||
848 db->db_state == DB_EVICTING) {
849 ASSERT(db->db.db_data == NULL);
850 mutex_exit(&db->db_mtx);
851 continue;
852 }
853 if (db->db_state == DB_READ || db->db_state == DB_FILL) {
854 /* will be handled in dbuf_read_done or dbuf_rele */
855 db->db_freed_in_flight = TRUE;
856 mutex_exit(&db->db_mtx);
857 continue;
858 }
859 if (refcount_count(&db->db_holds) == 0) {
860 ASSERT(db->db_buf);
861 dbuf_clear(db);
862 continue;
863 }
864 /* The dbuf is referenced */
865
866 if (db->db_last_dirty != NULL) {
867 dbuf_dirty_record_t *dr = db->db_last_dirty;
868
869 if (dr->dr_txg == txg) {
870 /*
871 * This buffer is "in-use", re-adjust the file
872 * size to reflect that this buffer may
873 * contain new data when we sync.
874 */
875 if (db->db_blkid != DMU_SPILL_BLKID &&
876 db->db_blkid > dn->dn_maxblkid)
877 dn->dn_maxblkid = db->db_blkid;
878 dbuf_unoverride(dr);
879 } else {
880 /*
881 * This dbuf is not dirty in the open context.
882 * Either uncache it (if its not referenced in
883 * the open context) or reset its contents to
884 * empty.
885 */
886 dbuf_fix_old_data(db, txg);
887 }
888 }
889 /* clear the contents if its cached */
890 if (db->db_state == DB_CACHED) {
891 ASSERT(db->db.db_data != NULL);
892 arc_release(db->db_buf, db);
893 bzero(db->db.db_data, db->db.db_size);
894 arc_buf_freeze(db->db_buf);
895 }
896
897 mutex_exit(&db->db_mtx);
898 }
899 mutex_exit(&dn->dn_dbufs_mtx);
900 }
901
902 static int
903 dbuf_block_freeable(dmu_buf_impl_t *db)
904 {
905 dsl_dataset_t *ds = db->db_objset->os_dsl_dataset;
906 uint64_t birth_txg = 0;
907
908 /*
909 * We don't need any locking to protect db_blkptr:
910 * If it's syncing, then db_last_dirty will be set
911 * so we'll ignore db_blkptr.
912 *
913 * This logic ensures that only block births for
914 * filled blocks are considered.
915 */
916 ASSERT(MUTEX_HELD(&db->db_mtx));
917 if (db->db_last_dirty && (db->db_blkptr == NULL ||
918 !BP_IS_HOLE(db->db_blkptr))) {
919 birth_txg = db->db_last_dirty->dr_txg;
920 } else if (db->db_blkptr != NULL && !BP_IS_HOLE(db->db_blkptr)) {
921 birth_txg = db->db_blkptr->blk_birth;
922 }
923
924 /*
925 * If this block don't exist or is in a snapshot, it can't be freed.
926 * Don't pass the bp to dsl_dataset_block_freeable() since we
927 * are holding the db_mtx lock and might deadlock if we are
928 * prefetching a dedup-ed block.
929 */
930 if (birth_txg != 0)
931 return (ds == NULL ||
932 dsl_dataset_block_freeable(ds, NULL, birth_txg));
933 else
934 return (B_FALSE);
935 }
936
937 void
938 dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx)
939 {
940 arc_buf_t *buf, *obuf;
941 int osize = db->db.db_size;
942 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
943 dnode_t *dn;
944
945 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
946
947 DB_DNODE_ENTER(db);
948 dn = DB_DNODE(db);
949
950 /* XXX does *this* func really need the lock? */
951 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
952
953 /*
954 * This call to dmu_buf_will_dirty() with the dn_struct_rwlock held
955 * is OK, because there can be no other references to the db
956 * when we are changing its size, so no concurrent DB_FILL can
957 * be happening.
958 */
959 /*
960 * XXX we should be doing a dbuf_read, checking the return
961 * value and returning that up to our callers
962 */
963 dmu_buf_will_dirty(&db->db, tx);
964
965 /* create the data buffer for the new block */
966 buf = arc_buf_alloc(dn->dn_objset->os_spa, size, db, type);
967
968 /* copy old block data to the new block */
969 obuf = db->db_buf;
970 bcopy(obuf->b_data, buf->b_data, MIN(osize, size));
971 /* zero the remainder */
972 if (size > osize)
973 bzero((uint8_t *)buf->b_data + osize, size - osize);
974
975 mutex_enter(&db->db_mtx);
976 dbuf_set_data(db, buf);
977 VERIFY(arc_buf_remove_ref(obuf, db));
978 db->db.db_size = size;
979
980 if (db->db_level == 0) {
981 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
982 db->db_last_dirty->dt.dl.dr_data = buf;
983 }
984 mutex_exit(&db->db_mtx);
985
986 dnode_willuse_space(dn, size-osize, tx);
987 DB_DNODE_EXIT(db);
988 }
989
990 void
991 dbuf_release_bp(dmu_buf_impl_t *db)
992 {
993 objset_t *os = db->db_objset;
994
995 ASSERT(dsl_pool_sync_context(dmu_objset_pool(os)));
996 ASSERT(arc_released(os->os_phys_buf) ||
997 list_link_active(&os->os_dsl_dataset->ds_synced_link));
998 ASSERT(db->db_parent == NULL || arc_released(db->db_parent->db_buf));
999
1000 (void) arc_release(db->db_buf, db);
1001 }
1002
1003 dbuf_dirty_record_t *
1004 dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1005 {
1006 dnode_t *dn;
1007 objset_t *os;
1008 dbuf_dirty_record_t **drp, *dr;
1009 int drop_struct_lock = FALSE;
1010 boolean_t do_free_accounting = B_FALSE;
1011 int txgoff = tx->tx_txg & TXG_MASK;
1012
1013 ASSERT(tx->tx_txg != 0);
1014 ASSERT(!refcount_is_zero(&db->db_holds));
1015 DMU_TX_DIRTY_BUF(tx, db);
1016
1017 DB_DNODE_ENTER(db);
1018 dn = DB_DNODE(db);
1019 /*
1020 * Shouldn't dirty a regular buffer in syncing context. Private
1021 * objects may be dirtied in syncing context, but only if they
1022 * were already pre-dirtied in open context.
1023 */
1024 ASSERT(!dmu_tx_is_syncing(tx) ||
1025 BP_IS_HOLE(dn->dn_objset->os_rootbp) ||
1026 DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1027 dn->dn_objset->os_dsl_dataset == NULL);
1028 /*
1029 * We make this assert for private objects as well, but after we
1030 * check if we're already dirty. They are allowed to re-dirty
1031 * in syncing context.
1032 */
1033 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1034 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1035 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1036
1037 mutex_enter(&db->db_mtx);
1038 /*
1039 * XXX make this true for indirects too? The problem is that
1040 * transactions created with dmu_tx_create_assigned() from
1041 * syncing context don't bother holding ahead.
1042 */
1043 ASSERT(db->db_level != 0 ||
1044 db->db_state == DB_CACHED || db->db_state == DB_FILL ||
1045 db->db_state == DB_NOFILL);
1046
1047 mutex_enter(&dn->dn_mtx);
1048 /*
1049 * Don't set dirtyctx to SYNC if we're just modifying this as we
1050 * initialize the objset.
1051 */
1052 if (dn->dn_dirtyctx == DN_UNDIRTIED &&
1053 !BP_IS_HOLE(dn->dn_objset->os_rootbp)) {
1054 dn->dn_dirtyctx =
1055 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN);
1056 ASSERT(dn->dn_dirtyctx_firstset == NULL);
1057 dn->dn_dirtyctx_firstset = kmem_alloc(1, KM_SLEEP);
1058 }
1059 mutex_exit(&dn->dn_mtx);
1060
1061 if (db->db_blkid == DMU_SPILL_BLKID)
1062 dn->dn_have_spill = B_TRUE;
1063
1064 /*
1065 * If this buffer is already dirty, we're done.
1066 */
1067 drp = &db->db_last_dirty;
1068 ASSERT(*drp == NULL || (*drp)->dr_txg <= tx->tx_txg ||
1069 db->db.db_object == DMU_META_DNODE_OBJECT);
1070 while ((dr = *drp) != NULL && dr->dr_txg > tx->tx_txg)
1071 drp = &dr->dr_next;
1072 if (dr && dr->dr_txg == tx->tx_txg) {
1073 DB_DNODE_EXIT(db);
1074
1075 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID) {
1076 /*
1077 * If this buffer has already been written out,
1078 * we now need to reset its state.
1079 */
1080 dbuf_unoverride(dr);
1081 if (db->db.db_object != DMU_META_DNODE_OBJECT &&
1082 db->db_state != DB_NOFILL)
1083 arc_buf_thaw(db->db_buf);
1084 }
1085 mutex_exit(&db->db_mtx);
1086 return (dr);
1087 }
1088
1089 /*
1090 * Only valid if not already dirty.
1091 */
1092 ASSERT(dn->dn_object == 0 ||
1093 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1094 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1095
1096 ASSERT3U(dn->dn_nlevels, >, db->db_level);
1097 ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) ||
1098 dn->dn_phys->dn_nlevels > db->db_level ||
1099 dn->dn_next_nlevels[txgoff] > db->db_level ||
1100 dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level ||
1101 dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level);
1102
1103 /*
1104 * We should only be dirtying in syncing context if it's the
1105 * mos or we're initializing the os or it's a special object.
1106 * However, we are allowed to dirty in syncing context provided
1107 * we already dirtied it in open context. Hence we must make
1108 * this assertion only if we're not already dirty.
1109 */
1110 os = dn->dn_objset;
1111 ASSERT(!dmu_tx_is_syncing(tx) || DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1112 os->os_dsl_dataset == NULL || BP_IS_HOLE(os->os_rootbp));
1113 ASSERT(db->db.db_size != 0);
1114
1115 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1116
1117 if (db->db_blkid != DMU_BONUS_BLKID) {
1118 /*
1119 * Update the accounting.
1120 * Note: we delay "free accounting" until after we drop
1121 * the db_mtx. This keeps us from grabbing other locks
1122 * (and possibly deadlocking) in bp_get_dsize() while
1123 * also holding the db_mtx.
1124 */
1125 dnode_willuse_space(dn, db->db.db_size, tx);
1126 do_free_accounting = dbuf_block_freeable(db);
1127 }
1128
1129 /*
1130 * If this buffer is dirty in an old transaction group we need
1131 * to make a copy of it so that the changes we make in this
1132 * transaction group won't leak out when we sync the older txg.
1133 */
1134 dr = kmem_zalloc(sizeof (dbuf_dirty_record_t), KM_SLEEP);
1135 if (db->db_level == 0) {
1136 void *data_old = db->db_buf;
1137
1138 if (db->db_state != DB_NOFILL) {
1139 if (db->db_blkid == DMU_BONUS_BLKID) {
1140 dbuf_fix_old_data(db, tx->tx_txg);
1141 data_old = db->db.db_data;
1142 } else if (db->db.db_object != DMU_META_DNODE_OBJECT) {
1143 /*
1144 * Release the data buffer from the cache so
1145 * that we can modify it without impacting
1146 * possible other users of this cached data
1147 * block. Note that indirect blocks and
1148 * private objects are not released until the
1149 * syncing state (since they are only modified
1150 * then).
1151 */
1152 arc_release(db->db_buf, db);
1153 dbuf_fix_old_data(db, tx->tx_txg);
1154 data_old = db->db_buf;
1155 }
1156 ASSERT(data_old != NULL);
1157 }
1158 dr->dt.dl.dr_data = data_old;
1159 } else {
1160 mutex_init(&dr->dt.di.dr_mtx, NULL, MUTEX_DEFAULT, NULL);
1161 list_create(&dr->dt.di.dr_children,
1162 sizeof (dbuf_dirty_record_t),
1163 offsetof(dbuf_dirty_record_t, dr_dirty_node));
1164 }
1165 if (db->db_blkid != DMU_BONUS_BLKID && os->os_dsl_dataset != NULL)
1166 dr->dr_accounted = db->db.db_size;
1167 dr->dr_dbuf = db;
1168 dr->dr_txg = tx->tx_txg;
1169 dr->dr_next = *drp;
1170 *drp = dr;
1171
1172 /*
1173 * We could have been freed_in_flight between the dbuf_noread
1174 * and dbuf_dirty. We win, as though the dbuf_noread() had
1175 * happened after the free.
1176 */
1177 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
1178 db->db_blkid != DMU_SPILL_BLKID) {
1179 mutex_enter(&dn->dn_mtx);
1180 dnode_clear_range(dn, db->db_blkid, 1, tx);
1181 mutex_exit(&dn->dn_mtx);
1182 db->db_freed_in_flight = FALSE;
1183 }
1184
1185 /*
1186 * This buffer is now part of this txg
1187 */
1188 dbuf_add_ref(db, (void *)(uintptr_t)tx->tx_txg);
1189 db->db_dirtycnt += 1;
1190 ASSERT3U(db->db_dirtycnt, <=, 3);
1191
1192 mutex_exit(&db->db_mtx);
1193
1194 if (db->db_blkid == DMU_BONUS_BLKID ||
1195 db->db_blkid == DMU_SPILL_BLKID) {
1196 mutex_enter(&dn->dn_mtx);
1197 ASSERT(!list_link_active(&dr->dr_dirty_node));
1198 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1199 mutex_exit(&dn->dn_mtx);
1200 dnode_setdirty(dn, tx);
1201 DB_DNODE_EXIT(db);
1202 return (dr);
1203 } else if (do_free_accounting) {
1204 blkptr_t *bp = db->db_blkptr;
1205 int64_t willfree = (bp && !BP_IS_HOLE(bp)) ?
1206 bp_get_dsize(os->os_spa, bp) : db->db.db_size;
1207 /*
1208 * This is only a guess -- if the dbuf is dirty
1209 * in a previous txg, we don't know how much
1210 * space it will use on disk yet. We should
1211 * really have the struct_rwlock to access
1212 * db_blkptr, but since this is just a guess,
1213 * it's OK if we get an odd answer.
1214 */
1215 ddt_prefetch(os->os_spa, bp);
1216 dnode_willuse_space(dn, -willfree, tx);
1217 }
1218
1219 if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
1220 rw_enter(&dn->dn_struct_rwlock, RW_READER);
1221 drop_struct_lock = TRUE;
1222 }
1223
1224 if (db->db_level == 0) {
1225 dnode_new_blkid(dn, db->db_blkid, tx, drop_struct_lock);
1226 ASSERT(dn->dn_maxblkid >= db->db_blkid);
1227 }
1228
1229 if (db->db_level+1 < dn->dn_nlevels) {
1230 dmu_buf_impl_t *parent = db->db_parent;
1231 dbuf_dirty_record_t *di;
1232 int parent_held = FALSE;
1233
1234 if (db->db_parent == NULL || db->db_parent == dn->dn_dbuf) {
1235 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1236
1237 parent = dbuf_hold_level(dn, db->db_level+1,
1238 db->db_blkid >> epbs, FTAG);
1239 ASSERT(parent != NULL);
1240 parent_held = TRUE;
1241 }
1242 if (drop_struct_lock)
1243 rw_exit(&dn->dn_struct_rwlock);
1244 ASSERT3U(db->db_level+1, ==, parent->db_level);
1245 di = dbuf_dirty(parent, tx);
1246 if (parent_held)
1247 dbuf_rele(parent, FTAG);
1248
1249 mutex_enter(&db->db_mtx);
1250 /*
1251 * Since we've dropped the mutex, it's possible that
1252 * dbuf_undirty() might have changed this out from under us.
1253 */
1254 if (db->db_last_dirty == dr ||
1255 dn->dn_object == DMU_META_DNODE_OBJECT) {
1256 mutex_enter(&di->dt.di.dr_mtx);
1257 ASSERT3U(di->dr_txg, ==, tx->tx_txg);
1258 ASSERT(!list_link_active(&dr->dr_dirty_node));
1259 list_insert_tail(&di->dt.di.dr_children, dr);
1260 mutex_exit(&di->dt.di.dr_mtx);
1261 dr->dr_parent = di;
1262 }
1263 mutex_exit(&db->db_mtx);
1264 } else {
1265 ASSERT(db->db_level+1 == dn->dn_nlevels);
1266 ASSERT(db->db_blkid < dn->dn_nblkptr);
1267 ASSERT(db->db_parent == NULL || db->db_parent == dn->dn_dbuf);
1268 mutex_enter(&dn->dn_mtx);
1269 ASSERT(!list_link_active(&dr->dr_dirty_node));
1270 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1271 mutex_exit(&dn->dn_mtx);
1272 if (drop_struct_lock)
1273 rw_exit(&dn->dn_struct_rwlock);
1274 }
1275
1276 dnode_setdirty(dn, tx);
1277 DB_DNODE_EXIT(db);
1278 return (dr);
1279 }
1280
1281 /*
1282 * Undirty a buffer in the transaction group referenced by the given
1283 * transaction. Return whether this evicted the dbuf.
1284 */
1285 static boolean_t
1286 dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1287 {
1288 dnode_t *dn;
1289 uint64_t txg = tx->tx_txg;
1290 dbuf_dirty_record_t *dr, **drp;
1291
1292 ASSERT(txg != 0);
1293 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1294 ASSERT0(db->db_level);
1295 ASSERT(MUTEX_HELD(&db->db_mtx));
1296
1297 /*
1298 * If this buffer is not dirty, we're done.
1299 */
1300 for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next)
1301 if (dr->dr_txg <= txg)
1302 break;
1303 if (dr == NULL || dr->dr_txg < txg)
1304 return (B_FALSE);
1305 ASSERT(dr->dr_txg == txg);
1306 ASSERT(dr->dr_dbuf == db);
1307
1308 DB_DNODE_ENTER(db);
1309 dn = DB_DNODE(db);
1310
1311 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1312
1313 ASSERT(db->db.db_size != 0);
1314
1315 /*
1316 * Any space we accounted for in dp_dirty_* will be cleaned up by
1317 * dsl_pool_sync(). This is relatively rare so the discrepancy
1318 * is not a big deal.
1319 */
1320
1321 *drp = dr->dr_next;
1322
1323 /*
1324 * Note that there are three places in dbuf_dirty()
1325 * where this dirty record may be put on a list.
1326 * Make sure to do a list_remove corresponding to
1327 * every one of those list_insert calls.
1328 */
1329 if (dr->dr_parent) {
1330 mutex_enter(&dr->dr_parent->dt.di.dr_mtx);
1331 list_remove(&dr->dr_parent->dt.di.dr_children, dr);
1332 mutex_exit(&dr->dr_parent->dt.di.dr_mtx);
1333 } else if (db->db_blkid == DMU_SPILL_BLKID ||
1334 db->db_level+1 == dn->dn_nlevels) {
1335 ASSERT(db->db_blkptr == NULL || db->db_parent == dn->dn_dbuf);
1336 mutex_enter(&dn->dn_mtx);
1337 list_remove(&dn->dn_dirty_records[txg & TXG_MASK], dr);
1338 mutex_exit(&dn->dn_mtx);
1339 }
1340 DB_DNODE_EXIT(db);
1341
1342 if (db->db_state != DB_NOFILL) {
1343 dbuf_unoverride(dr);
1344
1345 ASSERT(db->db_buf != NULL);
1346 ASSERT(dr->dt.dl.dr_data != NULL);
1347 if (dr->dt.dl.dr_data != db->db_buf)
1348 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data, db));
1349 }
1350 kmem_free(dr, sizeof (dbuf_dirty_record_t));
1351
1352 ASSERT(db->db_dirtycnt > 0);
1353 db->db_dirtycnt -= 1;
1354
1355 if (refcount_remove(&db->db_holds, (void *)(uintptr_t)txg) == 0) {
1356 arc_buf_t *buf = db->db_buf;
1357
1358 ASSERT(db->db_state == DB_NOFILL || arc_released(buf));
1359 dbuf_set_data(db, NULL);
1360 VERIFY(arc_buf_remove_ref(buf, db));
1361 dbuf_evict(db);
1362 return (B_TRUE);
1363 }
1364
1365 return (B_FALSE);
1366 }
1367
1368 void
1369 dmu_buf_will_dirty(dmu_buf_t *db_fake, dmu_tx_t *tx)
1370 {
1371 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1372 int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH;
1373
1374 ASSERT(tx->tx_txg != 0);
1375 ASSERT(!refcount_is_zero(&db->db_holds));
1376
1377 DB_DNODE_ENTER(db);
1378 if (RW_WRITE_HELD(&DB_DNODE(db)->dn_struct_rwlock))
1379 rf |= DB_RF_HAVESTRUCT;
1380 DB_DNODE_EXIT(db);
1381 (void) dbuf_read(db, NULL, rf);
1382 (void) dbuf_dirty(db, tx);
1383 }
1384
1385 void
1386 dmu_buf_will_not_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1387 {
1388 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1389
1390 db->db_state = DB_NOFILL;
1391
1392 dmu_buf_will_fill(db_fake, tx);
1393 }
1394
1395 void
1396 dmu_buf_will_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1397 {
1398 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1399
1400 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1401 ASSERT(tx->tx_txg != 0);
1402 ASSERT(db->db_level == 0);
1403 ASSERT(!refcount_is_zero(&db->db_holds));
1404
1405 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT ||
1406 dmu_tx_private_ok(tx));
1407
1408 dbuf_noread(db);
1409 (void) dbuf_dirty(db, tx);
1410 }
1411
1412 #pragma weak dmu_buf_fill_done = dbuf_fill_done
1413 /* ARGSUSED */
1414 void
1415 dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx)
1416 {
1417 mutex_enter(&db->db_mtx);
1418 DBUF_VERIFY(db);
1419
1420 if (db->db_state == DB_FILL) {
1421 if (db->db_level == 0 && db->db_freed_in_flight) {
1422 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1423 /* we were freed while filling */
1424 /* XXX dbuf_undirty? */
1425 bzero(db->db.db_data, db->db.db_size);
1426 db->db_freed_in_flight = FALSE;
1427 }
1428 db->db_state = DB_CACHED;
1429 cv_broadcast(&db->db_changed);
1430 }
1431 mutex_exit(&db->db_mtx);
1432 }
1433
1434 /*
1435 * Directly assign a provided arc buf to a given dbuf if it's not referenced
1436 * by anybody except our caller. Otherwise copy arcbuf's contents to dbuf.
1437 */
1438 void
1439 dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx)
1440 {
1441 ASSERT(!refcount_is_zero(&db->db_holds));
1442 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1443 ASSERT(db->db_level == 0);
1444 ASSERT(DBUF_GET_BUFC_TYPE(db) == ARC_BUFC_DATA);
1445 ASSERT(buf != NULL);
1446 ASSERT(arc_buf_size(buf) == db->db.db_size);
1447 ASSERT(tx->tx_txg != 0);
1448
1449 arc_return_buf(buf, db);
1450 ASSERT(arc_released(buf));
1451
1452 mutex_enter(&db->db_mtx);
1453
1454 while (db->db_state == DB_READ || db->db_state == DB_FILL)
1455 cv_wait(&db->db_changed, &db->db_mtx);
1456
1457 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED);
1458
1459 if (db->db_state == DB_CACHED &&
1460 refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) {
1461 mutex_exit(&db->db_mtx);
1462 (void) dbuf_dirty(db, tx);
1463 bcopy(buf->b_data, db->db.db_data, db->db.db_size);
1464 VERIFY(arc_buf_remove_ref(buf, db));
1465 xuio_stat_wbuf_copied();
1466 return;
1467 }
1468
1469 xuio_stat_wbuf_nocopy();
1470 if (db->db_state == DB_CACHED) {
1471 dbuf_dirty_record_t *dr = db->db_last_dirty;
1472
1473 ASSERT(db->db_buf != NULL);
1474 if (dr != NULL && dr->dr_txg == tx->tx_txg) {
1475 ASSERT(dr->dt.dl.dr_data == db->db_buf);
1476 if (!arc_released(db->db_buf)) {
1477 ASSERT(dr->dt.dl.dr_override_state ==
1478 DR_OVERRIDDEN);
1479 arc_release(db->db_buf, db);
1480 }
1481 dr->dt.dl.dr_data = buf;
1482 VERIFY(arc_buf_remove_ref(db->db_buf, db));
1483 } else if (dr == NULL || dr->dt.dl.dr_data != db->db_buf) {
1484 arc_release(db->db_buf, db);
1485 VERIFY(arc_buf_remove_ref(db->db_buf, db));
1486 }
1487 db->db_buf = NULL;
1488 }
1489 ASSERT(db->db_buf == NULL);
1490 dbuf_set_data(db, buf);
1491 db->db_state = DB_FILL;
1492 mutex_exit(&db->db_mtx);
1493 (void) dbuf_dirty(db, tx);
1494 dmu_buf_fill_done(&db->db, tx);
1495 }
1496
1497 /*
1498 * "Clear" the contents of this dbuf. This will mark the dbuf
1499 * EVICTING and clear *most* of its references. Unfortunately,
1500 * when we are not holding the dn_dbufs_mtx, we can't clear the
1501 * entry in the dn_dbufs list. We have to wait until dbuf_destroy()
1502 * in this case. For callers from the DMU we will usually see:
1503 * dbuf_clear()->arc_buf_evict()->dbuf_do_evict()->dbuf_destroy()
1504 * For the arc callback, we will usually see:
1505 * dbuf_do_evict()->dbuf_clear();dbuf_destroy()
1506 * Sometimes, though, we will get a mix of these two:
1507 * DMU: dbuf_clear()->arc_buf_evict()
1508 * ARC: dbuf_do_evict()->dbuf_destroy()
1509 */
1510 void
1511 dbuf_clear(dmu_buf_impl_t *db)
1512 {
1513 dnode_t *dn;
1514 dmu_buf_impl_t *parent = db->db_parent;
1515 dmu_buf_impl_t *dndb;
1516 int dbuf_gone = FALSE;
1517
1518 ASSERT(MUTEX_HELD(&db->db_mtx));
1519 ASSERT(refcount_is_zero(&db->db_holds));
1520
1521 dbuf_evict_user(db);
1522
1523 if (db->db_state == DB_CACHED) {
1524 ASSERT(db->db.db_data != NULL);
1525 if (db->db_blkid == DMU_BONUS_BLKID) {
1526 zio_buf_free(db->db.db_data, DN_MAX_BONUSLEN);
1527 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
1528 }
1529 db->db.db_data = NULL;
1530 db->db_state = DB_UNCACHED;
1531 }
1532
1533 ASSERT(db->db_state == DB_UNCACHED || db->db_state == DB_NOFILL);
1534 ASSERT(db->db_data_pending == NULL);
1535
1536 db->db_state = DB_EVICTING;
1537 db->db_blkptr = NULL;
1538
1539 DB_DNODE_ENTER(db);
1540 dn = DB_DNODE(db);
1541 dndb = dn->dn_dbuf;
1542 if (db->db_blkid != DMU_BONUS_BLKID && MUTEX_HELD(&dn->dn_dbufs_mtx)) {
1543 list_remove(&dn->dn_dbufs, db);
1544 (void) atomic_dec_32_nv(&dn->dn_dbufs_count);
1545 membar_producer();
1546 DB_DNODE_EXIT(db);
1547 /*
1548 * Decrementing the dbuf count means that the hold corresponding
1549 * to the removed dbuf is no longer discounted in dnode_move(),
1550 * so the dnode cannot be moved until after we release the hold.
1551 * The membar_producer() ensures visibility of the decremented
1552 * value in dnode_move(), since DB_DNODE_EXIT doesn't actually
1553 * release any lock.
1554 */
1555 dnode_rele(dn, db);
1556 db->db_dnode_handle = NULL;
1557 } else {
1558 DB_DNODE_EXIT(db);
1559 }
1560
1561 if (db->db_buf)
1562 dbuf_gone = arc_buf_evict(db->db_buf);
1563
1564 if (!dbuf_gone)
1565 mutex_exit(&db->db_mtx);
1566
1567 /*
1568 * If this dbuf is referenced from an indirect dbuf,
1569 * decrement the ref count on the indirect dbuf.
1570 */
1571 if (parent && parent != dndb)
1572 dbuf_rele(parent, db);
1573 }
1574
1575 static int
1576 dbuf_findbp(dnode_t *dn, int level, uint64_t blkid, int fail_sparse,
1577 dmu_buf_impl_t **parentp, blkptr_t **bpp)
1578 {
1579 int nlevels, epbs;
1580
1581 *parentp = NULL;
1582 *bpp = NULL;
1583
1584 ASSERT(blkid != DMU_BONUS_BLKID);
1585
1586 if (blkid == DMU_SPILL_BLKID) {
1587 mutex_enter(&dn->dn_mtx);
1588 if (dn->dn_have_spill &&
1589 (dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR))
1590 *bpp = &dn->dn_phys->dn_spill;
1591 else
1592 *bpp = NULL;
1593 dbuf_add_ref(dn->dn_dbuf, NULL);
1594 *parentp = dn->dn_dbuf;
1595 mutex_exit(&dn->dn_mtx);
1596 return (0);
1597 }
1598
1599 if (dn->dn_phys->dn_nlevels == 0)
1600 nlevels = 1;
1601 else
1602 nlevels = dn->dn_phys->dn_nlevels;
1603
1604 epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1605
1606 ASSERT3U(level * epbs, <, 64);
1607 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1608 if (level >= nlevels ||
1609 (blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))) {
1610 /* the buffer has no parent yet */
1611 return (SET_ERROR(ENOENT));
1612 } else if (level < nlevels-1) {
1613 /* this block is referenced from an indirect block */
1614 int err = dbuf_hold_impl(dn, level+1,
1615 blkid >> epbs, fail_sparse, NULL, parentp);
1616 if (err)
1617 return (err);
1618 err = dbuf_read(*parentp, NULL,
1619 (DB_RF_HAVESTRUCT | DB_RF_NOPREFETCH | DB_RF_CANFAIL));
1620 if (err) {
1621 dbuf_rele(*parentp, NULL);
1622 *parentp = NULL;
1623 return (err);
1624 }
1625 *bpp = ((blkptr_t *)(*parentp)->db.db_data) +
1626 (blkid & ((1ULL << epbs) - 1));
1627 return (0);
1628 } else {
1629 /* the block is referenced from the dnode */
1630 ASSERT3U(level, ==, nlevels-1);
1631 ASSERT(dn->dn_phys->dn_nblkptr == 0 ||
1632 blkid < dn->dn_phys->dn_nblkptr);
1633 if (dn->dn_dbuf) {
1634 dbuf_add_ref(dn->dn_dbuf, NULL);
1635 *parentp = dn->dn_dbuf;
1636 }
1637 *bpp = &dn->dn_phys->dn_blkptr[blkid];
1638 return (0);
1639 }
1640 }
1641
1642 static dmu_buf_impl_t *
1643 dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid,
1644 dmu_buf_impl_t *parent, blkptr_t *blkptr)
1645 {
1646 objset_t *os = dn->dn_objset;
1647 dmu_buf_impl_t *db, *odb;
1648
1649 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1650 ASSERT(dn->dn_type != DMU_OT_NONE);
1651
1652 db = kmem_cache_alloc(dbuf_cache, KM_SLEEP);
1653
1654 db->db_objset = os;
1655 db->db.db_object = dn->dn_object;
1656 db->db_level = level;
1657 db->db_blkid = blkid;
1658 db->db_last_dirty = NULL;
1659 db->db_dirtycnt = 0;
1660 db->db_dnode_handle = dn->dn_handle;
1661 db->db_parent = parent;
1662 db->db_blkptr = blkptr;
1663
1664 db->db_user_ptr = NULL;
1665 db->db_user_data_ptr_ptr = NULL;
1666 db->db_evict_func = NULL;
1667 db->db_immediate_evict = 0;
1668 db->db_freed_in_flight = 0;
1669
1670 if (blkid == DMU_BONUS_BLKID) {
1671 ASSERT3P(parent, ==, dn->dn_dbuf);
1672 db->db.db_size = DN_MAX_BONUSLEN -
1673 (dn->dn_nblkptr-1) * sizeof (blkptr_t);
1674 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
1675 db->db.db_offset = DMU_BONUS_BLKID;
1676 db->db_state = DB_UNCACHED;
1677 /* the bonus dbuf is not placed in the hash table */
1678 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1679 return (db);
1680 } else if (blkid == DMU_SPILL_BLKID) {
1681 db->db.db_size = (blkptr != NULL) ?
1682 BP_GET_LSIZE(blkptr) : SPA_MINBLOCKSIZE;
1683 db->db.db_offset = 0;
1684 } else {
1685 int blocksize =
1686 db->db_level ? 1 << dn->dn_indblkshift : dn->dn_datablksz;
1687 db->db.db_size = blocksize;
1688 db->db.db_offset = db->db_blkid * blocksize;
1689 }
1690
1691 /*
1692 * Hold the dn_dbufs_mtx while we get the new dbuf
1693 * in the hash table *and* added to the dbufs list.
1694 * This prevents a possible deadlock with someone
1695 * trying to look up this dbuf before its added to the
1696 * dn_dbufs list.
1697 */
1698 mutex_enter(&dn->dn_dbufs_mtx);
1699 db->db_state = DB_EVICTING;
1700 if ((odb = dbuf_hash_insert(db)) != NULL) {
1701 /* someone else inserted it first */
1702 kmem_cache_free(dbuf_cache, db);
1703 mutex_exit(&dn->dn_dbufs_mtx);
1704 return (odb);
1705 }
1706 list_insert_head(&dn->dn_dbufs, db);
1707 if (db->db_level == 0 && db->db_blkid >=
1708 dn->dn_unlisted_l0_blkid)
1709 dn->dn_unlisted_l0_blkid = db->db_blkid + 1;
1710 db->db_state = DB_UNCACHED;
1711 mutex_exit(&dn->dn_dbufs_mtx);
1712 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1713
1714 if (parent && parent != dn->dn_dbuf)
1715 dbuf_add_ref(parent, db);
1716
1717 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1718 refcount_count(&dn->dn_holds) > 0);
1719 (void) refcount_add(&dn->dn_holds, db);
1720 (void) atomic_inc_32_nv(&dn->dn_dbufs_count);
1721
1722 dprintf_dbuf(db, "db=%p\n", db);
1723
1724 return (db);
1725 }
1726
1727 static int
1728 dbuf_do_evict(void *private)
1729 {
1730 arc_buf_t *buf = private;
1731 dmu_buf_impl_t *db = buf->b_private;
1732
1733 if (!MUTEX_HELD(&db->db_mtx))
1734 mutex_enter(&db->db_mtx);
1735
1736 ASSERT(refcount_is_zero(&db->db_holds));
1737
1738 if (db->db_state != DB_EVICTING) {
1739 ASSERT(db->db_state == DB_CACHED);
1740 DBUF_VERIFY(db);
1741 db->db_buf = NULL;
1742 dbuf_evict(db);
1743 } else {
1744 mutex_exit(&db->db_mtx);
1745 dbuf_destroy(db);
1746 }
1747 return (0);
1748 }
1749
1750 static void
1751 dbuf_destroy(dmu_buf_impl_t *db)
1752 {
1753 ASSERT(refcount_is_zero(&db->db_holds));
1754
1755 if (db->db_blkid != DMU_BONUS_BLKID) {
1756 /*
1757 * If this dbuf is still on the dn_dbufs list,
1758 * remove it from that list.
1759 */
1760 if (db->db_dnode_handle != NULL) {
1761 dnode_t *dn;
1762
1763 DB_DNODE_ENTER(db);
1764 dn = DB_DNODE(db);
1765 mutex_enter(&dn->dn_dbufs_mtx);
1766 list_remove(&dn->dn_dbufs, db);
1767 (void) atomic_dec_32_nv(&dn->dn_dbufs_count);
1768 mutex_exit(&dn->dn_dbufs_mtx);
1769 DB_DNODE_EXIT(db);
1770 /*
1771 * Decrementing the dbuf count means that the hold
1772 * corresponding to the removed dbuf is no longer
1773 * discounted in dnode_move(), so the dnode cannot be
1774 * moved until after we release the hold.
1775 */
1776 dnode_rele(dn, db);
1777 db->db_dnode_handle = NULL;
1778 }
1779 dbuf_hash_remove(db);
1780 }
1781 db->db_parent = NULL;
1782 db->db_buf = NULL;
1783
1784 ASSERT(!list_link_active(&db->db_link));
1785 ASSERT(db->db.db_data == NULL);
1786 ASSERT(db->db_hash_next == NULL);
1787 ASSERT(db->db_blkptr == NULL);
1788 ASSERT(db->db_data_pending == NULL);
1789
1790 kmem_cache_free(dbuf_cache, db);
1791 arc_space_return(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1792 }
1793
1794 void
1795 dbuf_prefetch(dnode_t *dn, uint64_t blkid, zio_priority_t prio)
1796 {
1797 dmu_buf_impl_t *db = NULL;
1798 blkptr_t *bp = NULL;
1799
1800 ASSERT(blkid != DMU_BONUS_BLKID);
1801 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1802
1803 if (dnode_block_freed(dn, blkid))
1804 return;
1805
1806 /* dbuf_find() returns with db_mtx held */
1807 if (db = dbuf_find(dn, 0, blkid)) {
1808 /*
1809 * This dbuf is already in the cache. We assume that
1810 * it is already CACHED, or else about to be either
1811 * read or filled.
1812 */
1813 mutex_exit(&db->db_mtx);
1814 return;
1815 }
1816
1817 if (dbuf_findbp(dn, 0, blkid, TRUE, &db, &bp) == 0) {
1818 if (bp && !BP_IS_HOLE(bp)) {
1819 dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset;
1820 uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH;
1821 zbookmark_t zb;
1822
1823 SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
1824 dn->dn_object, 0, blkid);
1825
1826 (void) arc_read(NULL, dn->dn_objset->os_spa,
1827 bp, NULL, NULL, prio,
1828 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
1829 &aflags, &zb);
1830 }
1831 if (db)
1832 dbuf_rele(db, NULL);
1833 }
1834 }
1835
1836 /*
1837 * Returns with db_holds incremented, and db_mtx not held.
1838 * Note: dn_struct_rwlock must be held.
1839 */
1840 int
1841 dbuf_hold_impl(dnode_t *dn, uint8_t level, uint64_t blkid, int fail_sparse,
1842 void *tag, dmu_buf_impl_t **dbp)
1843 {
1844 dmu_buf_impl_t *db, *parent = NULL;
1845
1846 ASSERT(blkid != DMU_BONUS_BLKID);
1847 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1848 ASSERT3U(dn->dn_nlevels, >, level);
1849
1850 *dbp = NULL;
1851 top:
1852 /* dbuf_find() returns with db_mtx held */
1853 db = dbuf_find(dn, level, blkid);
1854
1855 if (db == NULL) {
1856 blkptr_t *bp = NULL;
1857 int err;
1858
1859 ASSERT3P(parent, ==, NULL);
1860 err = dbuf_findbp(dn, level, blkid, fail_sparse, &parent, &bp);
1861 if (fail_sparse) {
1862 if (err == 0 && bp && BP_IS_HOLE(bp))
1863 err = SET_ERROR(ENOENT);
1864 if (err) {
1865 if (parent)
1866 dbuf_rele(parent, NULL);
1867 return (err);
1868 }
1869 }
1870 if (err && err != ENOENT)
1871 return (err);
1872 db = dbuf_create(dn, level, blkid, parent, bp);
1873 }
1874
1875 if (db->db_buf && refcount_is_zero(&db->db_holds)) {
1876 arc_buf_add_ref(db->db_buf, db);
1877 if (db->db_buf->b_data == NULL) {
1878 dbuf_clear(db);
1879 if (parent) {
1880 dbuf_rele(parent, NULL);
1881 parent = NULL;
1882 }
1883 goto top;
1884 }
1885 ASSERT3P(db->db.db_data, ==, db->db_buf->b_data);
1886 }
1887
1888 ASSERT(db->db_buf == NULL || arc_referenced(db->db_buf));
1889
1890 /*
1891 * If this buffer is currently syncing out, and we are are
1892 * still referencing it from db_data, we need to make a copy
1893 * of it in case we decide we want to dirty it again in this txg.
1894 */
1895 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
1896 dn->dn_object != DMU_META_DNODE_OBJECT &&
1897 db->db_state == DB_CACHED && db->db_data_pending) {
1898 dbuf_dirty_record_t *dr = db->db_data_pending;
1899
1900 if (dr->dt.dl.dr_data == db->db_buf) {
1901 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
1902
1903 dbuf_set_data(db,
1904 arc_buf_alloc(dn->dn_objset->os_spa,
1905 db->db.db_size, db, type));
1906 bcopy(dr->dt.dl.dr_data->b_data, db->db.db_data,
1907 db->db.db_size);
1908 }
1909 }
1910
1911 (void) refcount_add(&db->db_holds, tag);
1912 dbuf_update_data(db);
1913 DBUF_VERIFY(db);
1914 mutex_exit(&db->db_mtx);
1915
1916 /* NOTE: we can't rele the parent until after we drop the db_mtx */
1917 if (parent)
1918 dbuf_rele(parent, NULL);
1919
1920 ASSERT3P(DB_DNODE(db), ==, dn);
1921 ASSERT3U(db->db_blkid, ==, blkid);
1922 ASSERT3U(db->db_level, ==, level);
1923 *dbp = db;
1924
1925 return (0);
1926 }
1927
1928 dmu_buf_impl_t *
1929 dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag)
1930 {
1931 dmu_buf_impl_t *db;
1932 int err = dbuf_hold_impl(dn, 0, blkid, FALSE, tag, &db);
1933 return (err ? NULL : db);
1934 }
1935
1936 dmu_buf_impl_t *
1937 dbuf_hold_level(dnode_t *dn, int level, uint64_t blkid, void *tag)
1938 {
1939 dmu_buf_impl_t *db;
1940 int err = dbuf_hold_impl(dn, level, blkid, FALSE, tag, &db);
1941 return (err ? NULL : db);
1942 }
1943
1944 void
1945 dbuf_create_bonus(dnode_t *dn)
1946 {
1947 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
1948
1949 ASSERT(dn->dn_bonus == NULL);
1950 dn->dn_bonus = dbuf_create(dn, 0, DMU_BONUS_BLKID, dn->dn_dbuf, NULL);
1951 }
1952
1953 int
1954 dbuf_spill_set_blksz(dmu_buf_t *db_fake, uint64_t blksz, dmu_tx_t *tx)
1955 {
1956 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1957 dnode_t *dn;
1958
1959 if (db->db_blkid != DMU_SPILL_BLKID)
1960 return (SET_ERROR(ENOTSUP));
1961 if (blksz == 0)
1962 blksz = SPA_MINBLOCKSIZE;
1963 if (blksz > SPA_MAXBLOCKSIZE)
1964 blksz = SPA_MAXBLOCKSIZE;
1965 else
1966 blksz = P2ROUNDUP(blksz, SPA_MINBLOCKSIZE);
1967
1968 DB_DNODE_ENTER(db);
1969 dn = DB_DNODE(db);
1970 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
1971 dbuf_new_size(db, blksz, tx);
1972 rw_exit(&dn->dn_struct_rwlock);
1973 DB_DNODE_EXIT(db);
1974
1975 return (0);
1976 }
1977
1978 void
1979 dbuf_rm_spill(dnode_t *dn, dmu_tx_t *tx)
1980 {
1981 dbuf_free_range(dn, DMU_SPILL_BLKID, DMU_SPILL_BLKID, tx);
1982 }
1983
1984 #pragma weak dmu_buf_add_ref = dbuf_add_ref
1985 void
1986 dbuf_add_ref(dmu_buf_impl_t *db, void *tag)
1987 {
1988 int64_t holds = refcount_add(&db->db_holds, tag);
1989 ASSERT(holds > 1);
1990 }
1991
1992 /*
1993 * If you call dbuf_rele() you had better not be referencing the dnode handle
1994 * unless you have some other direct or indirect hold on the dnode. (An indirect
1995 * hold is a hold on one of the dnode's dbufs, including the bonus buffer.)
1996 * Without that, the dbuf_rele() could lead to a dnode_rele() followed by the
1997 * dnode's parent dbuf evicting its dnode handles.
1998 */
1999 void
2000 dbuf_rele(dmu_buf_impl_t *db, void *tag)
2001 {
2002 mutex_enter(&db->db_mtx);
2003 dbuf_rele_and_unlock(db, tag);
2004 }
2005
2006 void
2007 dmu_buf_rele(dmu_buf_t *db, void *tag)
2008 {
2009 dbuf_rele((dmu_buf_impl_t *)db, tag);
2010 }
2011
2012 /*
2013 * dbuf_rele() for an already-locked dbuf. This is necessary to allow
2014 * db_dirtycnt and db_holds to be updated atomically.
2015 */
2016 void
2017 dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag)
2018 {
2019 int64_t holds;
2020
2021 ASSERT(MUTEX_HELD(&db->db_mtx));
2022 DBUF_VERIFY(db);
2023
2024 /*
2025 * Remove the reference to the dbuf before removing its hold on the
2026 * dnode so we can guarantee in dnode_move() that a referenced bonus
2027 * buffer has a corresponding dnode hold.
2028 */
2029 holds = refcount_remove(&db->db_holds, tag);
2030 ASSERT(holds >= 0);
2031
2032 /*
2033 * We can't freeze indirects if there is a possibility that they
2034 * may be modified in the current syncing context.
2035 */
2036 if (db->db_buf && holds == (db->db_level == 0 ? db->db_dirtycnt : 0))
2037 arc_buf_freeze(db->db_buf);
2038
2039 if (holds == db->db_dirtycnt &&
2040 db->db_level == 0 && db->db_immediate_evict)
2041 dbuf_evict_user(db);
2042
2043 if (holds == 0) {
2044 if (db->db_blkid == DMU_BONUS_BLKID) {
2045 mutex_exit(&db->db_mtx);
2046
2047 /*
2048 * If the dnode moves here, we cannot cross this barrier
2049 * until the move completes.
2050 */
2051 DB_DNODE_ENTER(db);
2052 (void) atomic_dec_32_nv(&DB_DNODE(db)->dn_dbufs_count);
2053 DB_DNODE_EXIT(db);
2054 /*
2055 * The bonus buffer's dnode hold is no longer discounted
2056 * in dnode_move(). The dnode cannot move until after
2057 * the dnode_rele().
2058 */
2059 dnode_rele(DB_DNODE(db), db);
2060 } else if (db->db_buf == NULL) {
2061 /*
2062 * This is a special case: we never associated this
2063 * dbuf with any data allocated from the ARC.
2064 */
2065 ASSERT(db->db_state == DB_UNCACHED ||
2066 db->db_state == DB_NOFILL);
2067 dbuf_evict(db);
2068 } else if (arc_released(db->db_buf)) {
2069 arc_buf_t *buf = db->db_buf;
2070 /*
2071 * This dbuf has anonymous data associated with it.
2072 */
2073 dbuf_set_data(db, NULL);
2074 VERIFY(arc_buf_remove_ref(buf, db));
2075 dbuf_evict(db);
2076 } else {
2077 VERIFY(!arc_buf_remove_ref(db->db_buf, db));
2078
2079 /*
2080 * A dbuf will be eligible for eviction if either the
2081 * 'primarycache' property is set or a duplicate
2082 * copy of this buffer is already cached in the arc.
2083 *
2084 * In the case of the 'primarycache' a buffer
2085 * is considered for eviction if it matches the
2086 * criteria set in the property.
2087 *
2088 * To decide if our buffer is considered a
2089 * duplicate, we must call into the arc to determine
2090 * if multiple buffers are referencing the same
2091 * block on-disk. If so, then we simply evict
2092 * ourselves.
2093 */
2094 if (!DBUF_IS_CACHEABLE(db) ||
2095 arc_buf_eviction_needed(db->db_buf))
2096 dbuf_clear(db);
2097 else
2098 mutex_exit(&db->db_mtx);
2099 }
2100 } else {
2101 mutex_exit(&db->db_mtx);
2102 }
2103 }
2104
2105 #pragma weak dmu_buf_refcount = dbuf_refcount
2106 uint64_t
2107 dbuf_refcount(dmu_buf_impl_t *db)
2108 {
2109 return (refcount_count(&db->db_holds));
2110 }
2111
2112 void *
2113 dmu_buf_set_user(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr,
2114 dmu_buf_evict_func_t *evict_func)
2115 {
2116 return (dmu_buf_update_user(db_fake, NULL, user_ptr,
2117 user_data_ptr_ptr, evict_func));
2118 }
2119
2120 void *
2121 dmu_buf_set_user_ie(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr,
2122 dmu_buf_evict_func_t *evict_func)
2123 {
2124 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2125
2126 db->db_immediate_evict = TRUE;
2127 return (dmu_buf_update_user(db_fake, NULL, user_ptr,
2128 user_data_ptr_ptr, evict_func));
2129 }
2130
2131 void *
2132 dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr, void *user_ptr,
2133 void *user_data_ptr_ptr, dmu_buf_evict_func_t *evict_func)
2134 {
2135 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2136 ASSERT(db->db_level == 0);
2137
2138 ASSERT((user_ptr == NULL) == (evict_func == NULL));
2139
2140 mutex_enter(&db->db_mtx);
2141
2142 if (db->db_user_ptr == old_user_ptr) {
2143 db->db_user_ptr = user_ptr;
2144 db->db_user_data_ptr_ptr = user_data_ptr_ptr;
2145 db->db_evict_func = evict_func;
2146
2147 dbuf_update_data(db);
2148 } else {
2149 old_user_ptr = db->db_user_ptr;
2150 }
2151
2152 mutex_exit(&db->db_mtx);
2153 return (old_user_ptr);
2154 }
2155
2156 void *
2157 dmu_buf_get_user(dmu_buf_t *db_fake)
2158 {
2159 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2160 ASSERT(!refcount_is_zero(&db->db_holds));
2161
2162 return (db->db_user_ptr);
2163 }
2164
2165 boolean_t
2166 dmu_buf_freeable(dmu_buf_t *dbuf)
2167 {
2168 boolean_t res = B_FALSE;
2169 dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf;
2170
2171 if (db->db_blkptr)
2172 res = dsl_dataset_block_freeable(db->db_objset->os_dsl_dataset,
2173 db->db_blkptr, db->db_blkptr->blk_birth);
2174
2175 return (res);
2176 }
2177
2178 blkptr_t *
2179 dmu_buf_get_blkptr(dmu_buf_t *db)
2180 {
2181 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
2182 return (dbi->db_blkptr);
2183 }
2184
2185 static void
2186 dbuf_check_blkptr(dnode_t *dn, dmu_buf_impl_t *db)
2187 {
2188 /* ASSERT(dmu_tx_is_syncing(tx) */
2189 ASSERT(MUTEX_HELD(&db->db_mtx));
2190
2191 if (db->db_blkptr != NULL)
2192 return;
2193
2194 if (db->db_blkid == DMU_SPILL_BLKID) {
2195 db->db_blkptr = &dn->dn_phys->dn_spill;
2196 BP_ZERO(db->db_blkptr);
2197 return;
2198 }
2199 if (db->db_level == dn->dn_phys->dn_nlevels-1) {
2200 /*
2201 * This buffer was allocated at a time when there was
2202 * no available blkptrs from the dnode, or it was
2203 * inappropriate to hook it in (i.e., nlevels mis-match).
2204 */
2205 ASSERT(db->db_blkid < dn->dn_phys->dn_nblkptr);
2206 ASSERT(db->db_parent == NULL);
2207 db->db_parent = dn->dn_dbuf;
2208 db->db_blkptr = &dn->dn_phys->dn_blkptr[db->db_blkid];
2209 DBUF_VERIFY(db);
2210 } else {
2211 dmu_buf_impl_t *parent = db->db_parent;
2212 int epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2213
2214 ASSERT(dn->dn_phys->dn_nlevels > 1);
2215 if (parent == NULL) {
2216 mutex_exit(&db->db_mtx);
2217 rw_enter(&dn->dn_struct_rwlock, RW_READER);
2218 (void) dbuf_hold_impl(dn, db->db_level+1,
2219 db->db_blkid >> epbs, FALSE, db, &parent);
2220 rw_exit(&dn->dn_struct_rwlock);
2221 mutex_enter(&db->db_mtx);
2222 db->db_parent = parent;
2223 }
2224 db->db_blkptr = (blkptr_t *)parent->db.db_data +
2225 (db->db_blkid & ((1ULL << epbs) - 1));
2226 DBUF_VERIFY(db);
2227 }
2228 }
2229
2230 static void
2231 dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
2232 {
2233 dmu_buf_impl_t *db = dr->dr_dbuf;
2234 dnode_t *dn;
2235 zio_t *zio;
2236
2237 ASSERT(dmu_tx_is_syncing(tx));
2238
2239 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
2240
2241 mutex_enter(&db->db_mtx);
2242
2243 ASSERT(db->db_level > 0);
2244 DBUF_VERIFY(db);
2245
2246 /* Read the block if it hasn't been read yet. */
2247 if (db->db_buf == NULL) {
2248 mutex_exit(&db->db_mtx);
2249 (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED);
2250 mutex_enter(&db->db_mtx);
2251 }
2252 ASSERT3U(db->db_state, ==, DB_CACHED);
2253 ASSERT(db->db_buf != NULL);
2254
2255 DB_DNODE_ENTER(db);
2256 dn = DB_DNODE(db);
2257 /* Indirect block size must match what the dnode thinks it is. */
2258 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2259 dbuf_check_blkptr(dn, db);
2260 DB_DNODE_EXIT(db);
2261
2262 /* Provide the pending dirty record to child dbufs */
2263 db->db_data_pending = dr;
2264
2265 mutex_exit(&db->db_mtx);
2266 dbuf_write(dr, db->db_buf, tx);
2267
2268 zio = dr->dr_zio;
2269 mutex_enter(&dr->dt.di.dr_mtx);
2270 dbuf_sync_list(&dr->dt.di.dr_children, tx);
2271 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
2272 mutex_exit(&dr->dt.di.dr_mtx);
2273 zio_nowait(zio);
2274 }
2275
2276 static void
2277 dbuf_sync_leaf(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
2278 {
2279 arc_buf_t **datap = &dr->dt.dl.dr_data;
2280 dmu_buf_impl_t *db = dr->dr_dbuf;
2281 dnode_t *dn;
2282 objset_t *os;
2283 uint64_t txg = tx->tx_txg;
2284
2285 ASSERT(dmu_tx_is_syncing(tx));
2286
2287 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
2288
2289 mutex_enter(&db->db_mtx);
2290 /*
2291 * To be synced, we must be dirtied. But we
2292 * might have been freed after the dirty.
2293 */
2294 if (db->db_state == DB_UNCACHED) {
2295 /* This buffer has been freed since it was dirtied */
2296 ASSERT(db->db.db_data == NULL);
2297 } else if (db->db_state == DB_FILL) {
2298 /* This buffer was freed and is now being re-filled */
2299 ASSERT(db->db.db_data != dr->dt.dl.dr_data);
2300 } else {
2301 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_NOFILL);
2302 }
2303 DBUF_VERIFY(db);
2304
2305 DB_DNODE_ENTER(db);
2306 dn = DB_DNODE(db);
2307
2308 if (db->db_blkid == DMU_SPILL_BLKID) {
2309 mutex_enter(&dn->dn_mtx);
2310 dn->dn_phys->dn_flags |= DNODE_FLAG_SPILL_BLKPTR;
2311 mutex_exit(&dn->dn_mtx);
2312 }
2313
2314 /*
2315 * If this is a bonus buffer, simply copy the bonus data into the
2316 * dnode. It will be written out when the dnode is synced (and it
2317 * will be synced, since it must have been dirty for dbuf_sync to
2318 * be called).
2319 */
2320 if (db->db_blkid == DMU_BONUS_BLKID) {
2321 dbuf_dirty_record_t **drp;
2322
2323 ASSERT(*datap != NULL);
2324 ASSERT0(db->db_level);
2325 ASSERT3U(dn->dn_phys->dn_bonuslen, <=, DN_MAX_BONUSLEN);
2326 bcopy(*datap, DN_BONUS(dn->dn_phys), dn->dn_phys->dn_bonuslen);
2327 DB_DNODE_EXIT(db);
2328
2329 if (*datap != db->db.db_data) {
2330 zio_buf_free(*datap, DN_MAX_BONUSLEN);
2331 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
2332 }
2333 db->db_data_pending = NULL;
2334 drp = &db->db_last_dirty;
2335 while (*drp != dr)
2336 drp = &(*drp)->dr_next;
2337 ASSERT(dr->dr_next == NULL);
2338 ASSERT(dr->dr_dbuf == db);
2339 *drp = dr->dr_next;
2340 kmem_free(dr, sizeof (dbuf_dirty_record_t));
2341 ASSERT(db->db_dirtycnt > 0);
2342 db->db_dirtycnt -= 1;
2343 dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg);
2344 return;
2345 }
2346
2347 os = dn->dn_objset;
2348
2349 /*
2350 * This function may have dropped the db_mtx lock allowing a dmu_sync
2351 * operation to sneak in. As a result, we need to ensure that we
2352 * don't check the dr_override_state until we have returned from
2353 * dbuf_check_blkptr.
2354 */
2355 dbuf_check_blkptr(dn, db);
2356
2357 /*
2358 * If this buffer is in the middle of an immediate write,
2359 * wait for the synchronous IO to complete.
2360 */
2361 while (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC) {
2362 ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
2363 cv_wait(&db->db_changed, &db->db_mtx);
2364 ASSERT(dr->dt.dl.dr_override_state != DR_NOT_OVERRIDDEN);
2365 }
2366
2367 if (db->db_state != DB_NOFILL &&
2368 dn->dn_object != DMU_META_DNODE_OBJECT &&
2369 refcount_count(&db->db_holds) > 1 &&
2370 dr->dt.dl.dr_override_state != DR_OVERRIDDEN &&
2371 *datap == db->db_buf) {
2372 /*
2373 * If this buffer is currently "in use" (i.e., there
2374 * are active holds and db_data still references it),
2375 * then make a copy before we start the write so that
2376 * any modifications from the open txg will not leak
2377 * into this write.
2378 *
2379 * NOTE: this copy does not need to be made for
2380 * objects only modified in the syncing context (e.g.
2381 * DNONE_DNODE blocks).
2382 */
2383 int blksz = arc_buf_size(*datap);
2384 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
2385 *datap = arc_buf_alloc(os->os_spa, blksz, db, type);
2386 bcopy(db->db.db_data, (*datap)->b_data, blksz);
2387 }
2388 db->db_data_pending = dr;
2389
2390 mutex_exit(&db->db_mtx);
2391
2392 dbuf_write(dr, *datap, tx);
2393
2394 ASSERT(!list_link_active(&dr->dr_dirty_node));
2395 if (dn->dn_object == DMU_META_DNODE_OBJECT) {
2396 list_insert_tail(&dn->dn_dirty_records[txg&TXG_MASK], dr);
2397 DB_DNODE_EXIT(db);
2398 } else {
2399 /*
2400 * Although zio_nowait() does not "wait for an IO", it does
2401 * initiate the IO. If this is an empty write it seems plausible
2402 * that the IO could actually be completed before the nowait
2403 * returns. We need to DB_DNODE_EXIT() first in case
2404 * zio_nowait() invalidates the dbuf.
2405 */
2406 DB_DNODE_EXIT(db);
2407 zio_nowait(dr->dr_zio);
2408 }
2409 }
2410
2411 void
2412 dbuf_sync_list(list_t *list, dmu_tx_t *tx)
2413 {
2414 dbuf_dirty_record_t *dr;
2415
2416 while (dr = list_head(list)) {
2417 if (dr->dr_zio != NULL) {
2418 /*
2419 * If we find an already initialized zio then we
2420 * are processing the meta-dnode, and we have finished.
2421 * The dbufs for all dnodes are put back on the list
2422 * during processing, so that we can zio_wait()
2423 * these IOs after initiating all child IOs.
2424 */
2425 ASSERT3U(dr->dr_dbuf->db.db_object, ==,
2426 DMU_META_DNODE_OBJECT);
2427 break;
2428 }
2429 list_remove(list, dr);
2430 if (dr->dr_dbuf->db_level > 0)
2431 dbuf_sync_indirect(dr, tx);
2432 else
2433 dbuf_sync_leaf(dr, tx);
2434 }
2435 }
2436
2437 /* ARGSUSED */
2438 static void
2439 dbuf_write_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
2440 {
2441 dmu_buf_impl_t *db = vdb;
2442 dnode_t *dn;
2443 blkptr_t *bp = zio->io_bp;
2444 blkptr_t *bp_orig = &zio->io_bp_orig;
2445 spa_t *spa = zio->io_spa;
2446 int64_t delta;
2447 uint64_t fill = 0;
2448 int i;
2449
2450 ASSERT(db->db_blkptr == bp);
2451
2452 DB_DNODE_ENTER(db);
2453 dn = DB_DNODE(db);
2454 delta = bp_get_dsize_sync(spa, bp) - bp_get_dsize_sync(spa, bp_orig);
2455 dnode_diduse_space(dn, delta - zio->io_prev_space_delta);
2456 zio->io_prev_space_delta = delta;
2457
2458 if (bp->blk_birth != 0) {
2459 ASSERT((db->db_blkid != DMU_SPILL_BLKID &&
2460 BP_GET_TYPE(bp) == dn->dn_type) ||
2461 (db->db_blkid == DMU_SPILL_BLKID &&
2462 BP_GET_TYPE(bp) == dn->dn_bonustype));
2463 ASSERT(BP_GET_LEVEL(bp) == db->db_level);
2464 }
2465
2466 mutex_enter(&db->db_mtx);
2467
2468 #ifdef ZFS_DEBUG
2469 if (db->db_blkid == DMU_SPILL_BLKID) {
2470 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
2471 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
2472 db->db_blkptr == &dn->dn_phys->dn_spill);
2473 }
2474 #endif
2475
2476 if (db->db_level == 0) {
2477 mutex_enter(&dn->dn_mtx);
2478 if (db->db_blkid > dn->dn_phys->dn_maxblkid &&
2479 db->db_blkid != DMU_SPILL_BLKID)
2480 dn->dn_phys->dn_maxblkid = db->db_blkid;
2481 mutex_exit(&dn->dn_mtx);
2482
2483 if (dn->dn_type == DMU_OT_DNODE) {
2484 dnode_phys_t *dnp = db->db.db_data;
2485 for (i = db->db.db_size >> DNODE_SHIFT; i > 0;
2486 i--, dnp++) {
2487 if (dnp->dn_type != DMU_OT_NONE)
2488 fill++;
2489 }
2490 } else {
2491 if (BP_IS_HOLE(bp)) {
2492 fill = 0;
2493 } else {
2494 fill = 1;
2495 }
2496 }
2497 } else {
2498 blkptr_t *ibp = db->db.db_data;
2499 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2500 for (i = db->db.db_size >> SPA_BLKPTRSHIFT; i > 0; i--, ibp++) {
2501 if (BP_IS_HOLE(ibp))
2502 continue;
2503 fill += ibp->blk_fill;
2504 }
2505 }
2506 DB_DNODE_EXIT(db);
2507
2508 bp->blk_fill = fill;
2509
2510 mutex_exit(&db->db_mtx);
2511 }
2512
2513 /*
2514 * The SPA will call this callback several times for each zio - once
2515 * for every physical child i/o (zio->io_phys_children times). This
2516 * allows the DMU to monitor the progress of each logical i/o. For example,
2517 * there may be 2 copies of an indirect block, or many fragments of a RAID-Z
2518 * block. There may be a long delay before all copies/fragments are completed,
2519 * so this callback allows us to retire dirty space gradually, as the physical
2520 * i/os complete.
2521 */
2522 /* ARGSUSED */
2523 static void
2524 dbuf_write_physdone(zio_t *zio, arc_buf_t *buf, void *arg)
2525 {
2526 dmu_buf_impl_t *db = arg;
2527 objset_t *os = db->db_objset;
2528 dsl_pool_t *dp = dmu_objset_pool(os);
2529 dbuf_dirty_record_t *dr;
2530 int delta = 0;
2531
2532 dr = db->db_data_pending;
2533 ASSERT3U(dr->dr_txg, ==, zio->io_txg);
2534
2535 /*
2536 * The callback will be called io_phys_children times. Retire one
2537 * portion of our dirty space each time we are called. Any rounding
2538 * error will be cleaned up by dsl_pool_sync()'s call to
2539 * dsl_pool_undirty_space().
2540 */
2541 delta = dr->dr_accounted / zio->io_phys_children;
2542 dsl_pool_undirty_space(dp, delta, zio->io_txg);
2543 }
2544
2545 /* ARGSUSED */
2546 static void
2547 dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb)
2548 {
2549 dmu_buf_impl_t *db = vdb;
2550 blkptr_t *bp_orig = &zio->io_bp_orig;
2551 blkptr_t *bp = db->db_blkptr;
2552 objset_t *os = db->db_objset;
2553 dmu_tx_t *tx = os->os_synctx;
2554 dbuf_dirty_record_t **drp, *dr;
2555
2556 ASSERT0(zio->io_error);
2557 ASSERT(db->db_blkptr == bp);
2558
2559 /*
2560 * For nopwrites and rewrites we ensure that the bp matches our
2561 * original and bypass all the accounting.
2562 */
2563 if (zio->io_flags & (ZIO_FLAG_IO_REWRITE | ZIO_FLAG_NOPWRITE)) {
2564 ASSERT(BP_EQUAL(bp, bp_orig));
2565 } else {
2566 dsl_dataset_t *ds = os->os_dsl_dataset;
2567 (void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE);
2568 dsl_dataset_block_born(ds, bp, tx);
2569 }
2570
2571 mutex_enter(&db->db_mtx);
2572
2573 DBUF_VERIFY(db);
2574
2575 drp = &db->db_last_dirty;
2576 while ((dr = *drp) != db->db_data_pending)
2577 drp = &dr->dr_next;
2578 ASSERT(!list_link_active(&dr->dr_dirty_node));
2579 ASSERT(dr->dr_dbuf == db);
2580 ASSERT(dr->dr_next == NULL);
2581 *drp = dr->dr_next;
2582
2583 #ifdef ZFS_DEBUG
2584 if (db->db_blkid == DMU_SPILL_BLKID) {
2585 dnode_t *dn;
2586
2587 DB_DNODE_ENTER(db);
2588 dn = DB_DNODE(db);
2589 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
2590 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
2591 db->db_blkptr == &dn->dn_phys->dn_spill);
2592 DB_DNODE_EXIT(db);
2593 }
2594 #endif
2595
2596 if (db->db_level == 0) {
2597 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
2598 ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
2599 if (db->db_state != DB_NOFILL) {
2600 if (dr->dt.dl.dr_data != db->db_buf)
2601 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data,
2602 db));
2603 else if (!arc_released(db->db_buf))
2604 arc_set_callback(db->db_buf, dbuf_do_evict, db);
2605 }
2606 } else {
2607 dnode_t *dn;
2608
2609 DB_DNODE_ENTER(db);
2610 dn = DB_DNODE(db);
2611 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
2612 ASSERT3U(db->db.db_size, ==, 1 << dn->dn_phys->dn_indblkshift);
2613 if (!BP_IS_HOLE(db->db_blkptr)) {
2614 int epbs =
2615 dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2616 ASSERT3U(db->db_blkid, <=,
2617 dn->dn_phys->dn_maxblkid >> (db->db_level * epbs));
2618 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==,
2619 db->db.db_size);
2620 arc_set_callback(db->db_buf, dbuf_do_evict, db);
2621 }
2622 DB_DNODE_EXIT(db);
2623 mutex_destroy(&dr->dt.di.dr_mtx);
2624 list_destroy(&dr->dt.di.dr_children);
2625 }
2626 kmem_free(dr, sizeof (dbuf_dirty_record_t));
2627
2628 cv_broadcast(&db->db_changed);
2629 ASSERT(db->db_dirtycnt > 0);
2630 db->db_dirtycnt -= 1;
2631 db->db_data_pending = NULL;
2632 dbuf_rele_and_unlock(db, (void *)(uintptr_t)tx->tx_txg);
2633 }
2634
2635 static void
2636 dbuf_write_nofill_ready(zio_t *zio)
2637 {
2638 dbuf_write_ready(zio, NULL, zio->io_private);
2639 }
2640
2641 static void
2642 dbuf_write_nofill_done(zio_t *zio)
2643 {
2644 dbuf_write_done(zio, NULL, zio->io_private);
2645 }
2646
2647 static void
2648 dbuf_write_override_ready(zio_t *zio)
2649 {
2650 dbuf_dirty_record_t *dr = zio->io_private;
2651 dmu_buf_impl_t *db = dr->dr_dbuf;
2652
2653 dbuf_write_ready(zio, NULL, db);
2654 }
2655
2656 static void
2657 dbuf_write_override_done(zio_t *zio)
2658 {
2659 dbuf_dirty_record_t *dr = zio->io_private;
2660 dmu_buf_impl_t *db = dr->dr_dbuf;
2661 blkptr_t *obp = &dr->dt.dl.dr_overridden_by;
2662
2663 mutex_enter(&db->db_mtx);
2664 if (!BP_EQUAL(zio->io_bp, obp)) {
2665 if (!BP_IS_HOLE(obp))
2666 dsl_free(spa_get_dsl(zio->io_spa), zio->io_txg, obp);
2667 arc_release(dr->dt.dl.dr_data, db);
2668 }
2669 mutex_exit(&db->db_mtx);
2670
2671 dbuf_write_done(zio, NULL, db);
2672 }
2673
2674 /* Issue I/O to commit a dirty buffer to disk. */
2675 static void
2676 dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx)
2677 {
2678 dmu_buf_impl_t *db = dr->dr_dbuf;
2679 dnode_t *dn;
2680 objset_t *os;
2681 dmu_buf_impl_t *parent = db->db_parent;
2682 uint64_t txg = tx->tx_txg;
2683 zbookmark_t zb;
2684 zio_prop_t zp;
2685 zio_t *zio;
2686 int wp_flag = 0;
2687
2688 DB_DNODE_ENTER(db);
2689 dn = DB_DNODE(db);
2690 os = dn->dn_objset;
2691
2692 if (db->db_state != DB_NOFILL) {
2693 if (db->db_level > 0 || dn->dn_type == DMU_OT_DNODE) {
2694 /*
2695 * Private object buffers are released here rather
2696 * than in dbuf_dirty() since they are only modified
2697 * in the syncing context and we don't want the
2698 * overhead of making multiple copies of the data.
2699 */
2700 if (BP_IS_HOLE(db->db_blkptr)) {
2701 arc_buf_thaw(data);
2702 } else {
2703 dbuf_release_bp(db);
2704 }
2705 }
2706 }
2707
2708 if (parent != dn->dn_dbuf) {
2709 /* Our parent is an indirect block. */
2710 /* We have a dirty parent that has been scheduled for write. */
2711 ASSERT(parent && parent->db_data_pending);
2712 /* Our parent's buffer is one level closer to the dnode. */
2713 ASSERT(db->db_level == parent->db_level-1);
2714 /*
2715 * We're about to modify our parent's db_data by modifying
2716 * our block pointer, so the parent must be released.
2717 */
2718 ASSERT(arc_released(parent->db_buf));
2719 zio = parent->db_data_pending->dr_zio;
2720 } else {
2721 /* Our parent is the dnode itself. */
2722 ASSERT((db->db_level == dn->dn_phys->dn_nlevels-1 &&
2723 db->db_blkid != DMU_SPILL_BLKID) ||
2724 (db->db_blkid == DMU_SPILL_BLKID && db->db_level == 0));
2725 if (db->db_blkid != DMU_SPILL_BLKID)
2726 ASSERT3P(db->db_blkptr, ==,
2727 &dn->dn_phys->dn_blkptr[db->db_blkid]);
2728 zio = dn->dn_zio;
2729 }
2730
2731 ASSERT(db->db_level == 0 || data == db->db_buf);
2732 ASSERT3U(db->db_blkptr->blk_birth, <=, txg);
2733 ASSERT(zio);
2734
2735 SET_BOOKMARK(&zb, os->os_dsl_dataset ?
2736 os->os_dsl_dataset->ds_object : DMU_META_OBJSET,
2737 db->db.db_object, db->db_level, db->db_blkid);
2738
2739 if (db->db_blkid == DMU_SPILL_BLKID)
2740 wp_flag = WP_SPILL;
2741 wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0;
2742
2743 dmu_write_policy(os, dn, db->db_level, wp_flag, &zp);
2744 DB_DNODE_EXIT(db);
2745
2746 if (db->db_level == 0 && dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
2747 ASSERT(db->db_state != DB_NOFILL);
2748 dr->dr_zio = zio_write(zio, os->os_spa, txg,
2749 db->db_blkptr, data->b_data, arc_buf_size(data), &zp,
2750 dbuf_write_override_ready, NULL, dbuf_write_override_done,
2751 dr, ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
2752 mutex_enter(&db->db_mtx);
2753 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
2754 zio_write_override(dr->dr_zio, &dr->dt.dl.dr_overridden_by,
2755 dr->dt.dl.dr_copies, dr->dt.dl.dr_nopwrite);
2756 mutex_exit(&db->db_mtx);
2757 } else if (db->db_state == DB_NOFILL) {
2758 ASSERT(zp.zp_checksum == ZIO_CHECKSUM_OFF ||
2759 zp.zp_checksum == ZIO_CHECKSUM_NOPARITY);
2760 dr->dr_zio = zio_write(zio, os->os_spa, txg,
2761 db->db_blkptr, NULL, db->db.db_size, &zp,
2762 dbuf_write_nofill_ready, NULL, dbuf_write_nofill_done, db,
2763 ZIO_PRIORITY_ASYNC_WRITE,
2764 ZIO_FLAG_MUSTSUCCEED | ZIO_FLAG_NODATA, &zb);
2765 } else {
2766 ASSERT(arc_released(data));
2767 dr->dr_zio = arc_write(zio, os->os_spa, txg,
2768 db->db_blkptr, data, DBUF_IS_L2CACHEABLE(db),
2769 DBUF_IS_L2COMPRESSIBLE(db), &zp, dbuf_write_ready,
2770 dbuf_write_physdone, dbuf_write_done, db,
2771 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
2772 }
2773 }