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 */
27
28 #include <sys/zfs_context.h>
29 #include <sys/dmu.h>
30 #include <sys/dmu_send.h>
31 #include <sys/dmu_impl.h>
32 #include <sys/dbuf.h>
33 #include <sys/dmu_objset.h>
34 #include <sys/dsl_dataset.h>
35 #include <sys/dsl_dir.h>
36 #include <sys/dmu_tx.h>
37 #include <sys/spa.h>
38 #include <sys/zio.h>
39 #include <sys/dmu_zfetch.h>
40 #include <sys/sa.h>
41 #include <sys/sa_impl.h>
42
43 static void dbuf_destroy(dmu_buf_impl_t *db);
44 static boolean_t dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
45 static void dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx);
46
47 /*
48 * Global data structures and functions for the dbuf cache.
49 */
50 static kmem_cache_t *dbuf_cache;
51
52 /* ARGSUSED */
53 static int
54 dbuf_cons(void *vdb, void *unused, int kmflag)
55 {
56 dmu_buf_impl_t *db = vdb;
57 bzero(db, sizeof (dmu_buf_impl_t));
58
59 mutex_init(&db->db_mtx, NULL, MUTEX_DEFAULT, NULL);
60 cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL);
61 refcount_create(&db->db_holds);
62 return (0);
63 }
64
65 /* ARGSUSED */
66 static void
67 dbuf_dest(void *vdb, void *unused)
68 {
69 dmu_buf_impl_t *db = vdb;
70 mutex_destroy(&db->db_mtx);
71 cv_destroy(&db->db_changed);
72 refcount_destroy(&db->db_holds);
73 }
74
75 /*
76 * dbuf hash table routines
77 */
78 static dbuf_hash_table_t dbuf_hash_table;
79
80 static uint64_t dbuf_hash_count;
81
82 static uint64_t
83 dbuf_hash(void *os, uint64_t obj, uint8_t lvl, uint64_t blkid)
84 {
85 uintptr_t osv = (uintptr_t)os;
86 uint64_t crc = -1ULL;
87
88 ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY);
89 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (lvl)) & 0xFF];
90 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (osv >> 6)) & 0xFF];
91 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 0)) & 0xFF];
92 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 8)) & 0xFF];
93 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 0)) & 0xFF];
94 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 8)) & 0xFF];
95
96 crc ^= (osv>>14) ^ (obj>>16) ^ (blkid>>16);
97
98 return (crc);
99 }
100
101 #define DBUF_HASH(os, obj, level, blkid) dbuf_hash(os, obj, level, blkid);
102
103 #define DBUF_EQUAL(dbuf, os, obj, level, blkid) \
104 ((dbuf)->db.db_object == (obj) && \
105 (dbuf)->db_objset == (os) && \
106 (dbuf)->db_level == (level) && \
107 (dbuf)->db_blkid == (blkid))
108
109 dmu_buf_impl_t *
110 dbuf_find(dnode_t *dn, uint8_t level, uint64_t blkid)
111 {
112 dbuf_hash_table_t *h = &dbuf_hash_table;
113 objset_t *os = dn->dn_objset;
114 uint64_t obj = dn->dn_object;
115 uint64_t hv = DBUF_HASH(os, obj, level, blkid);
116 uint64_t idx = hv & h->hash_table_mask;
117 dmu_buf_impl_t *db;
118
119 mutex_enter(DBUF_HASH_MUTEX(h, idx));
120 for (db = h->hash_table[idx]; db != NULL; db = db->db_hash_next) {
121 if (DBUF_EQUAL(db, os, obj, level, blkid)) {
122 mutex_enter(&db->db_mtx);
123 if (db->db_state != DB_EVICTING) {
124 mutex_exit(DBUF_HASH_MUTEX(h, idx));
125 return (db);
126 }
127 mutex_exit(&db->db_mtx);
128 }
129 }
130 mutex_exit(DBUF_HASH_MUTEX(h, idx));
131 return (NULL);
132 }
133
134 /*
135 * Insert an entry into the hash table. If there is already an element
136 * equal to elem in the hash table, then the already existing element
137 * will be returned and the new element will not be inserted.
138 * Otherwise returns NULL.
139 */
140 static dmu_buf_impl_t *
141 dbuf_hash_insert(dmu_buf_impl_t *db)
142 {
143 dbuf_hash_table_t *h = &dbuf_hash_table;
144 objset_t *os = db->db_objset;
145 uint64_t obj = db->db.db_object;
146 int level = db->db_level;
147 uint64_t blkid = db->db_blkid;
148 uint64_t hv = DBUF_HASH(os, obj, level, blkid);
149 uint64_t idx = hv & h->hash_table_mask;
150 dmu_buf_impl_t *dbf;
151
152 mutex_enter(DBUF_HASH_MUTEX(h, idx));
153 for (dbf = h->hash_table[idx]; dbf != NULL; dbf = dbf->db_hash_next) {
154 if (DBUF_EQUAL(dbf, os, obj, level, blkid)) {
155 mutex_enter(&dbf->db_mtx);
156 if (dbf->db_state != DB_EVICTING) {
157 mutex_exit(DBUF_HASH_MUTEX(h, idx));
158 return (dbf);
159 }
160 mutex_exit(&dbf->db_mtx);
161 }
162 }
163
164 mutex_enter(&db->db_mtx);
165 db->db_hash_next = h->hash_table[idx];
166 h->hash_table[idx] = db;
167 mutex_exit(DBUF_HASH_MUTEX(h, idx));
168 atomic_add_64(&dbuf_hash_count, 1);
169
170 return (NULL);
171 }
172
173 /*
174 * Remove an entry from the hash table. This operation will
175 * fail if there are any existing holds on the db.
176 */
177 static void
178 dbuf_hash_remove(dmu_buf_impl_t *db)
179 {
180 dbuf_hash_table_t *h = &dbuf_hash_table;
181 uint64_t hv = DBUF_HASH(db->db_objset, db->db.db_object,
182 db->db_level, db->db_blkid);
183 uint64_t idx = hv & h->hash_table_mask;
184 dmu_buf_impl_t *dbf, **dbp;
185
186 /*
187 * We musn't hold db_mtx to maintin lock ordering:
188 * DBUF_HASH_MUTEX > db_mtx.
189 */
190 ASSERT(refcount_is_zero(&db->db_holds));
191 ASSERT(db->db_state == DB_EVICTING);
192 ASSERT(!MUTEX_HELD(&db->db_mtx));
193
194 mutex_enter(DBUF_HASH_MUTEX(h, idx));
195 dbp = &h->hash_table[idx];
196 while ((dbf = *dbp) != db) {
197 dbp = &dbf->db_hash_next;
198 ASSERT(dbf != NULL);
199 }
200 *dbp = db->db_hash_next;
201 db->db_hash_next = NULL;
202 mutex_exit(DBUF_HASH_MUTEX(h, idx));
203 atomic_add_64(&dbuf_hash_count, -1);
204 }
205
206 static arc_evict_func_t dbuf_do_evict;
207
208 static void
209 dbuf_evict_user(dmu_buf_impl_t *db)
210 {
211 ASSERT(MUTEX_HELD(&db->db_mtx));
212
213 if (db->db_level != 0 || db->db_evict_func == NULL)
214 return;
215
216 if (db->db_user_data_ptr_ptr)
217 *db->db_user_data_ptr_ptr = db->db.db_data;
218 db->db_evict_func(&db->db, db->db_user_ptr);
219 db->db_user_ptr = NULL;
220 db->db_user_data_ptr_ptr = NULL;
221 db->db_evict_func = NULL;
222 }
223
224 boolean_t
225 dbuf_is_metadata(dmu_buf_impl_t *db)
226 {
227 if (db->db_level > 0) {
228 return (B_TRUE);
229 } else {
230 boolean_t is_metadata;
231
232 DB_DNODE_ENTER(db);
233 is_metadata = DMU_OT_IS_METADATA(DB_DNODE(db)->dn_type);
234 DB_DNODE_EXIT(db);
235
236 return (is_metadata);
237 }
238 }
239
240 void
241 dbuf_evict(dmu_buf_impl_t *db)
242 {
243 ASSERT(MUTEX_HELD(&db->db_mtx));
244 ASSERT(db->db_buf == NULL);
245 ASSERT(db->db_data_pending == NULL);
246
247 dbuf_clear(db);
248 dbuf_destroy(db);
249 }
250
251 void
252 dbuf_init(void)
253 {
254 uint64_t hsize = 1ULL << 16;
255 dbuf_hash_table_t *h = &dbuf_hash_table;
256 int i;
257
258 /*
259 * The hash table is big enough to fill all of physical memory
260 * with an average 4K block size. The table will take up
261 * totalmem*sizeof(void*)/4K (i.e. 2MB/GB with 8-byte pointers).
262 */
263 while (hsize * 4096 < physmem * PAGESIZE)
264 hsize <<= 1;
265
266 retry:
267 h->hash_table_mask = hsize - 1;
268 h->hash_table = kmem_zalloc(hsize * sizeof (void *), KM_NOSLEEP);
269 if (h->hash_table == NULL) {
270 /* XXX - we should really return an error instead of assert */
271 ASSERT(hsize > (1ULL << 10));
272 hsize >>= 1;
273 goto retry;
274 }
275
276 dbuf_cache = kmem_cache_create("dmu_buf_impl_t",
277 sizeof (dmu_buf_impl_t),
278 0, dbuf_cons, dbuf_dest, NULL, NULL, NULL, 0);
279
280 for (i = 0; i < DBUF_MUTEXES; i++)
281 mutex_init(&h->hash_mutexes[i], NULL, MUTEX_DEFAULT, NULL);
282 }
283
284 void
285 dbuf_fini(void)
286 {
287 dbuf_hash_table_t *h = &dbuf_hash_table;
288 int i;
289
290 for (i = 0; i < DBUF_MUTEXES; i++)
291 mutex_destroy(&h->hash_mutexes[i]);
292 kmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *));
293 kmem_cache_destroy(dbuf_cache);
294 }
295
296 /*
297 * Other stuff.
298 */
299
300 #ifdef ZFS_DEBUG
301 static void
302 dbuf_verify(dmu_buf_impl_t *db)
303 {
304 dnode_t *dn;
305 dbuf_dirty_record_t *dr;
306
307 ASSERT(MUTEX_HELD(&db->db_mtx));
308
309 if (!(zfs_flags & ZFS_DEBUG_DBUF_VERIFY))
310 return;
311
312 ASSERT(db->db_objset != NULL);
313 DB_DNODE_ENTER(db);
314 dn = DB_DNODE(db);
315 if (dn == NULL) {
316 ASSERT(db->db_parent == NULL);
317 ASSERT(db->db_blkptr == NULL);
318 } else {
319 ASSERT3U(db->db.db_object, ==, dn->dn_object);
320 ASSERT3P(db->db_objset, ==, dn->dn_objset);
321 ASSERT3U(db->db_level, <, dn->dn_nlevels);
322 ASSERT(db->db_blkid == DMU_BONUS_BLKID ||
323 db->db_blkid == DMU_SPILL_BLKID ||
324 !list_is_empty(&dn->dn_dbufs));
325 }
326 if (db->db_blkid == DMU_BONUS_BLKID) {
327 ASSERT(dn != NULL);
328 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
329 ASSERT3U(db->db.db_offset, ==, DMU_BONUS_BLKID);
330 } else if (db->db_blkid == DMU_SPILL_BLKID) {
331 ASSERT(dn != NULL);
332 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
333 ASSERT0(db->db.db_offset);
334 } else {
335 ASSERT3U(db->db.db_offset, ==, db->db_blkid * db->db.db_size);
336 }
337
338 for (dr = db->db_data_pending; dr != NULL; dr = dr->dr_next)
339 ASSERT(dr->dr_dbuf == db);
340
341 for (dr = db->db_last_dirty; dr != NULL; dr = dr->dr_next)
342 ASSERT(dr->dr_dbuf == db);
343
344 /*
345 * We can't assert that db_size matches dn_datablksz because it
346 * can be momentarily different when another thread is doing
347 * dnode_set_blksz().
348 */
349 if (db->db_level == 0 && db->db.db_object == DMU_META_DNODE_OBJECT) {
350 dr = db->db_data_pending;
351 /*
352 * It should only be modified in syncing context, so
353 * make sure we only have one copy of the data.
354 */
355 ASSERT(dr == NULL || dr->dt.dl.dr_data == db->db_buf);
356 }
357
358 /* verify db->db_blkptr */
359 if (db->db_blkptr) {
360 if (db->db_parent == dn->dn_dbuf) {
361 /* db is pointed to by the dnode */
362 /* ASSERT3U(db->db_blkid, <, dn->dn_nblkptr); */
363 if (DMU_OBJECT_IS_SPECIAL(db->db.db_object))
364 ASSERT(db->db_parent == NULL);
365 else
366 ASSERT(db->db_parent != NULL);
367 if (db->db_blkid != DMU_SPILL_BLKID)
368 ASSERT3P(db->db_blkptr, ==,
369 &dn->dn_phys->dn_blkptr[db->db_blkid]);
370 } else {
371 /* db is pointed to by an indirect block */
372 int epb = db->db_parent->db.db_size >> SPA_BLKPTRSHIFT;
373 ASSERT3U(db->db_parent->db_level, ==, db->db_level+1);
374 ASSERT3U(db->db_parent->db.db_object, ==,
375 db->db.db_object);
376 /*
377 * dnode_grow_indblksz() can make this fail if we don't
378 * have the struct_rwlock. XXX indblksz no longer
379 * grows. safe to do this now?
380 */
381 if (RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
382 ASSERT3P(db->db_blkptr, ==,
383 ((blkptr_t *)db->db_parent->db.db_data +
384 db->db_blkid % epb));
385 }
386 }
387 }
388 if ((db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr)) &&
389 (db->db_buf == NULL || db->db_buf->b_data) &&
390 db->db.db_data && db->db_blkid != DMU_BONUS_BLKID &&
391 db->db_state != DB_FILL && !dn->dn_free_txg) {
392 /*
393 * If the blkptr isn't set but they have nonzero data,
394 * it had better be dirty, otherwise we'll lose that
395 * data when we evict this buffer.
396 */
397 if (db->db_dirtycnt == 0) {
398 uint64_t *buf = db->db.db_data;
399 int i;
400
401 for (i = 0; i < db->db.db_size >> 3; i++) {
402 ASSERT(buf[i] == 0);
403 }
404 }
405 }
406 DB_DNODE_EXIT(db);
407 }
408 #endif
409
410 static void
411 dbuf_update_data(dmu_buf_impl_t *db)
412 {
413 ASSERT(MUTEX_HELD(&db->db_mtx));
414 if (db->db_level == 0 && db->db_user_data_ptr_ptr) {
415 ASSERT(!refcount_is_zero(&db->db_holds));
416 *db->db_user_data_ptr_ptr = db->db.db_data;
417 }
418 }
419
420 static void
421 dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf)
422 {
423 ASSERT(MUTEX_HELD(&db->db_mtx));
424 ASSERT(db->db_buf == NULL || !arc_has_callback(db->db_buf));
425 db->db_buf = buf;
426 if (buf != NULL) {
427 ASSERT(buf->b_data != NULL);
428 db->db.db_data = buf->b_data;
429 if (!arc_released(buf))
430 arc_set_callback(buf, dbuf_do_evict, db);
431 dbuf_update_data(db);
432 } else {
433 dbuf_evict_user(db);
434 db->db.db_data = NULL;
435 if (db->db_state != DB_NOFILL)
436 db->db_state = DB_UNCACHED;
437 }
438 }
439
440 /*
441 * Loan out an arc_buf for read. Return the loaned arc_buf.
442 */
443 arc_buf_t *
444 dbuf_loan_arcbuf(dmu_buf_impl_t *db)
445 {
446 arc_buf_t *abuf;
447
448 mutex_enter(&db->db_mtx);
449 if (arc_released(db->db_buf) || refcount_count(&db->db_holds) > 1) {
450 int blksz = db->db.db_size;
451 spa_t *spa;
452
453 mutex_exit(&db->db_mtx);
454 DB_GET_SPA(&spa, db);
455 abuf = arc_loan_buf(spa, blksz);
456 bcopy(db->db.db_data, abuf->b_data, blksz);
457 } else {
458 abuf = db->db_buf;
459 arc_loan_inuse_buf(abuf, db);
460 dbuf_set_data(db, NULL);
461 mutex_exit(&db->db_mtx);
462 }
463 return (abuf);
464 }
465
466 uint64_t
467 dbuf_whichblock(dnode_t *dn, uint64_t offset)
468 {
469 if (dn->dn_datablkshift) {
470 return (offset >> dn->dn_datablkshift);
471 } else {
472 ASSERT3U(offset, <, dn->dn_datablksz);
473 return (0);
474 }
475 }
476
477 static void
478 dbuf_read_done(zio_t *zio, arc_buf_t *buf, void *vdb)
479 {
480 dmu_buf_impl_t *db = vdb;
481
482 mutex_enter(&db->db_mtx);
483 ASSERT3U(db->db_state, ==, DB_READ);
484 /*
485 * All reads are synchronous, so we must have a hold on the dbuf
486 */
487 ASSERT(refcount_count(&db->db_holds) > 0);
488 ASSERT(db->db_buf == NULL);
489 ASSERT(db->db.db_data == NULL);
490 if (db->db_level == 0 && db->db_freed_in_flight) {
491 /* we were freed in flight; disregard any error */
492 arc_release(buf, db);
493 bzero(buf->b_data, db->db.db_size);
494 arc_buf_freeze(buf);
495 db->db_freed_in_flight = FALSE;
496 dbuf_set_data(db, buf);
497 db->db_state = DB_CACHED;
498 } else if (zio == NULL || zio->io_error == 0) {
499 dbuf_set_data(db, buf);
500 db->db_state = DB_CACHED;
501 } else {
502 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
503 ASSERT3P(db->db_buf, ==, NULL);
504 VERIFY(arc_buf_remove_ref(buf, db));
505 db->db_state = DB_UNCACHED;
506 }
507 cv_broadcast(&db->db_changed);
508 dbuf_rele_and_unlock(db, NULL);
509 }
510
511 static void
512 dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t *flags)
513 {
514 dnode_t *dn;
515 spa_t *spa;
516 zbookmark_t zb;
517 uint32_t aflags = ARC_NOWAIT;
518
519 DB_DNODE_ENTER(db);
520 dn = DB_DNODE(db);
521 ASSERT(!refcount_is_zero(&db->db_holds));
522 /* We need the struct_rwlock to prevent db_blkptr from changing. */
523 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
524 ASSERT(MUTEX_HELD(&db->db_mtx));
525 ASSERT(db->db_state == DB_UNCACHED);
526 ASSERT(db->db_buf == NULL);
527
528 if (db->db_blkid == DMU_BONUS_BLKID) {
529 int bonuslen = MIN(dn->dn_bonuslen, dn->dn_phys->dn_bonuslen);
530
531 ASSERT3U(bonuslen, <=, db->db.db_size);
532 db->db.db_data = zio_buf_alloc(DN_MAX_BONUSLEN);
533 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
534 if (bonuslen < DN_MAX_BONUSLEN)
535 bzero(db->db.db_data, DN_MAX_BONUSLEN);
536 if (bonuslen)
537 bcopy(DN_BONUS(dn->dn_phys), db->db.db_data, bonuslen);
538 DB_DNODE_EXIT(db);
539 dbuf_update_data(db);
540 db->db_state = DB_CACHED;
541 mutex_exit(&db->db_mtx);
542 return;
543 }
544
545 /*
546 * Recheck BP_IS_HOLE() after dnode_block_freed() in case dnode_sync()
547 * processes the delete record and clears the bp while we are waiting
548 * for the dn_mtx (resulting in a "no" from block_freed).
549 */
550 if (db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr) ||
551 (db->db_level == 0 && (dnode_block_freed(dn, db->db_blkid) ||
552 BP_IS_HOLE(db->db_blkptr)))) {
553 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
554
555 dbuf_set_data(db, arc_buf_alloc(dn->dn_objset->os_spa,
556 db->db.db_size, db, type));
557 DB_DNODE_EXIT(db);
558 bzero(db->db.db_data, db->db.db_size);
559 db->db_state = DB_CACHED;
560 *flags |= DB_RF_CACHED;
561 mutex_exit(&db->db_mtx);
562 return;
563 }
564
565 spa = dn->dn_objset->os_spa;
566 DB_DNODE_EXIT(db);
567
568 db->db_state = DB_READ;
569 mutex_exit(&db->db_mtx);
570
571 if (DBUF_IS_L2CACHEABLE(db))
572 aflags |= ARC_L2CACHE;
573 if (DBUF_IS_L2COMPRESSIBLE(db))
574 aflags |= ARC_L2COMPRESS;
575
576 SET_BOOKMARK(&zb, db->db_objset->os_dsl_dataset ?
577 db->db_objset->os_dsl_dataset->ds_object : DMU_META_OBJSET,
578 db->db.db_object, db->db_level, db->db_blkid);
579
580 dbuf_add_ref(db, NULL);
581
582 (void) arc_read(zio, spa, db->db_blkptr,
583 dbuf_read_done, db, ZIO_PRIORITY_SYNC_READ,
584 (*flags & DB_RF_CANFAIL) ? ZIO_FLAG_CANFAIL : ZIO_FLAG_MUSTSUCCEED,
585 &aflags, &zb);
586 if (aflags & ARC_CACHED)
587 *flags |= DB_RF_CACHED;
588 }
589
590 int
591 dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
592 {
593 int err = 0;
594 int havepzio = (zio != NULL);
595 int prefetch;
596 dnode_t *dn;
597
598 /*
599 * We don't have to hold the mutex to check db_state because it
600 * can't be freed while we have a hold on the buffer.
601 */
602 ASSERT(!refcount_is_zero(&db->db_holds));
603
604 if (db->db_state == DB_NOFILL)
605 return (SET_ERROR(EIO));
606
607 DB_DNODE_ENTER(db);
608 dn = DB_DNODE(db);
609 if ((flags & DB_RF_HAVESTRUCT) == 0)
610 rw_enter(&dn->dn_struct_rwlock, RW_READER);
611
612 prefetch = db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
613 (flags & DB_RF_NOPREFETCH) == 0 && dn != NULL &&
614 DBUF_IS_CACHEABLE(db);
615
616 mutex_enter(&db->db_mtx);
617 if (db->db_state == DB_CACHED) {
618 mutex_exit(&db->db_mtx);
619 if (prefetch)
620 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset,
621 db->db.db_size, TRUE);
622 if ((flags & DB_RF_HAVESTRUCT) == 0)
623 rw_exit(&dn->dn_struct_rwlock);
624 DB_DNODE_EXIT(db);
625 } else if (db->db_state == DB_UNCACHED) {
626 spa_t *spa = dn->dn_objset->os_spa;
627
628 if (zio == NULL)
629 zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL);
630 dbuf_read_impl(db, zio, &flags);
631
632 /* dbuf_read_impl has dropped db_mtx for us */
633
634 if (prefetch)
635 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset,
636 db->db.db_size, flags & DB_RF_CACHED);
637
638 if ((flags & DB_RF_HAVESTRUCT) == 0)
639 rw_exit(&dn->dn_struct_rwlock);
640 DB_DNODE_EXIT(db);
641
642 if (!havepzio)
643 err = zio_wait(zio);
644 } else {
645 /*
646 * Another reader came in while the dbuf was in flight
647 * between UNCACHED and CACHED. Either a writer will finish
648 * writing the buffer (sending the dbuf to CACHED) or the
649 * first reader's request will reach the read_done callback
650 * and send the dbuf to CACHED. Otherwise, a failure
651 * occurred and the dbuf went to UNCACHED.
652 */
653 mutex_exit(&db->db_mtx);
654 if (prefetch)
655 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset,
656 db->db.db_size, TRUE);
657 if ((flags & DB_RF_HAVESTRUCT) == 0)
658 rw_exit(&dn->dn_struct_rwlock);
659 DB_DNODE_EXIT(db);
660
661 /* Skip the wait per the caller's request. */
662 mutex_enter(&db->db_mtx);
663 if ((flags & DB_RF_NEVERWAIT) == 0) {
664 while (db->db_state == DB_READ ||
665 db->db_state == DB_FILL) {
666 ASSERT(db->db_state == DB_READ ||
667 (flags & DB_RF_HAVESTRUCT) == 0);
668 cv_wait(&db->db_changed, &db->db_mtx);
669 }
670 if (db->db_state == DB_UNCACHED)
671 err = SET_ERROR(EIO);
672 }
673 mutex_exit(&db->db_mtx);
674 }
675
676 ASSERT(err || havepzio || db->db_state == DB_CACHED);
677 return (err);
678 }
679
680 static void
681 dbuf_noread(dmu_buf_impl_t *db)
682 {
683 ASSERT(!refcount_is_zero(&db->db_holds));
684 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
685 mutex_enter(&db->db_mtx);
686 while (db->db_state == DB_READ || db->db_state == DB_FILL)
687 cv_wait(&db->db_changed, &db->db_mtx);
688 if (db->db_state == DB_UNCACHED) {
689 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
690 spa_t *spa;
691
692 ASSERT(db->db_buf == NULL);
693 ASSERT(db->db.db_data == NULL);
694 DB_GET_SPA(&spa, db);
695 dbuf_set_data(db, arc_buf_alloc(spa, db->db.db_size, db, type));
696 db->db_state = DB_FILL;
697 } else if (db->db_state == DB_NOFILL) {
698 dbuf_set_data(db, NULL);
699 } else {
700 ASSERT3U(db->db_state, ==, DB_CACHED);
701 }
702 mutex_exit(&db->db_mtx);
703 }
704
705 /*
706 * This is our just-in-time copy function. It makes a copy of
707 * buffers, that have been modified in a previous transaction
708 * group, before we modify them in the current active group.
709 *
710 * This function is used in two places: when we are dirtying a
711 * buffer for the first time in a txg, and when we are freeing
712 * a range in a dnode that includes this buffer.
713 *
714 * Note that when we are called from dbuf_free_range() we do
715 * not put a hold on the buffer, we just traverse the active
716 * dbuf list for the dnode.
717 */
718 static void
719 dbuf_fix_old_data(dmu_buf_impl_t *db, uint64_t txg)
720 {
721 dbuf_dirty_record_t *dr = db->db_last_dirty;
722
723 ASSERT(MUTEX_HELD(&db->db_mtx));
724 ASSERT(db->db.db_data != NULL);
725 ASSERT(db->db_level == 0);
726 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT);
727
728 if (dr == NULL ||
729 (dr->dt.dl.dr_data !=
730 ((db->db_blkid == DMU_BONUS_BLKID) ? db->db.db_data : db->db_buf)))
731 return;
732
733 /*
734 * If the last dirty record for this dbuf has not yet synced
735 * and its referencing the dbuf data, either:
736 * reset the reference to point to a new copy,
737 * or (if there a no active holders)
738 * just null out the current db_data pointer.
739 */
740 ASSERT(dr->dr_txg >= txg - 2);
741 if (db->db_blkid == DMU_BONUS_BLKID) {
742 /* Note that the data bufs here are zio_bufs */
743 dr->dt.dl.dr_data = zio_buf_alloc(DN_MAX_BONUSLEN);
744 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
745 bcopy(db->db.db_data, dr->dt.dl.dr_data, DN_MAX_BONUSLEN);
746 } else if (refcount_count(&db->db_holds) > db->db_dirtycnt) {
747 int size = db->db.db_size;
748 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
749 spa_t *spa;
750
751 DB_GET_SPA(&spa, db);
752 dr->dt.dl.dr_data = arc_buf_alloc(spa, size, db, type);
753 bcopy(db->db.db_data, dr->dt.dl.dr_data->b_data, size);
754 } else {
755 dbuf_set_data(db, NULL);
756 }
757 }
758
759 void
760 dbuf_unoverride(dbuf_dirty_record_t *dr)
761 {
762 dmu_buf_impl_t *db = dr->dr_dbuf;
763 blkptr_t *bp = &dr->dt.dl.dr_overridden_by;
764 uint64_t txg = dr->dr_txg;
765
766 ASSERT(MUTEX_HELD(&db->db_mtx));
767 ASSERT(dr->dt.dl.dr_override_state != DR_IN_DMU_SYNC);
768 ASSERT(db->db_level == 0);
769
770 if (db->db_blkid == DMU_BONUS_BLKID ||
771 dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN)
772 return;
773
774 ASSERT(db->db_data_pending != dr);
775
776 /* free this block */
777 if (!BP_IS_HOLE(bp) && !dr->dt.dl.dr_nopwrite) {
778 spa_t *spa;
779
780 DB_GET_SPA(&spa, db);
781 zio_free(spa, txg, bp);
782 }
783 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
784 dr->dt.dl.dr_nopwrite = B_FALSE;
785
786 /*
787 * Release the already-written buffer, so we leave it in
788 * a consistent dirty state. Note that all callers are
789 * modifying the buffer, so they will immediately do
790 * another (redundant) arc_release(). Therefore, leave
791 * the buf thawed to save the effort of freezing &
792 * immediately re-thawing it.
793 */
794 arc_release(dr->dt.dl.dr_data, db);
795 }
796
797 /*
798 * Evict (if its unreferenced) or clear (if its referenced) any level-0
799 * data blocks in the free range, so that any future readers will find
800 * empty blocks. Also, if we happen across any level-1 dbufs in the
801 * range that have not already been marked dirty, mark them dirty so
802 * they stay in memory.
803 *
804 * This is a no-op if the dataset is in the middle of an incremental
805 * receive; see comment below for details.
806 */
807 void
808 dbuf_free_range(dnode_t *dn, uint64_t start, uint64_t end, dmu_tx_t *tx)
809 {
810 dmu_buf_impl_t *db, *db_next;
811 uint64_t txg = tx->tx_txg;
812 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
813 uint64_t first_l1 = start >> epbs;
814 uint64_t last_l1 = end >> epbs;
815
816 if (end > dn->dn_maxblkid && (end != DMU_SPILL_BLKID)) {
817 end = dn->dn_maxblkid;
818 last_l1 = end >> epbs;
819 }
820 dprintf_dnode(dn, "start=%llu end=%llu\n", start, end);
821
822 if (dmu_objset_is_receiving(dn->dn_objset)) {
823 /*
824 * When processing a free record from a zfs receive,
825 * there should have been no previous modifications to the
826 * data in this range. Therefore there should be no dbufs
827 * in the range. Searching dn_dbufs for these non-existent
828 * dbufs can be very expensive, so simply ignore this.
829 */
830 VERIFY3P(dbuf_find(dn, 0, start), ==, NULL);
831 VERIFY3P(dbuf_find(dn, 0, end), ==, NULL);
832 return;
833 }
834
835 mutex_enter(&dn->dn_dbufs_mtx);
836 for (db = list_head(&dn->dn_dbufs); db; db = db_next) {
837 db_next = list_next(&dn->dn_dbufs, db);
838 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
839
840 if (db->db_level == 1 &&
841 db->db_blkid >= first_l1 && db->db_blkid <= last_l1) {
842 mutex_enter(&db->db_mtx);
843 if (db->db_last_dirty &&
844 db->db_last_dirty->dr_txg < txg) {
845 dbuf_add_ref(db, FTAG);
846 mutex_exit(&db->db_mtx);
847 dbuf_will_dirty(db, tx);
848 dbuf_rele(db, FTAG);
849 } else {
850 mutex_exit(&db->db_mtx);
851 }
852 }
853
854 if (db->db_level != 0)
855 continue;
856 dprintf_dbuf(db, "found buf %s\n", "");
857 if (db->db_blkid < start || db->db_blkid > end)
858 continue;
859
860 /* found a level 0 buffer in the range */
861 mutex_enter(&db->db_mtx);
862 if (dbuf_undirty(db, tx)) {
863 /* mutex has been dropped and dbuf destroyed */
864 continue;
865 }
866
867 if (db->db_state == DB_UNCACHED ||
868 db->db_state == DB_NOFILL ||
869 db->db_state == DB_EVICTING) {
870 ASSERT(db->db.db_data == NULL);
871 mutex_exit(&db->db_mtx);
872 continue;
873 }
874 if (db->db_state == DB_READ || db->db_state == DB_FILL) {
875 /* will be handled in dbuf_read_done or dbuf_rele */
876 db->db_freed_in_flight = TRUE;
877 mutex_exit(&db->db_mtx);
878 continue;
879 }
880 if (refcount_count(&db->db_holds) == 0) {
881 ASSERT(db->db_buf);
882 dbuf_clear(db);
883 continue;
884 }
885 /* The dbuf is referenced */
886
887 if (db->db_last_dirty != NULL) {
888 dbuf_dirty_record_t *dr = db->db_last_dirty;
889
890 if (dr->dr_txg == txg) {
891 /*
892 * This buffer is "in-use", re-adjust the file
893 * size to reflect that this buffer may
894 * contain new data when we sync.
895 */
896 if (db->db_blkid != DMU_SPILL_BLKID &&
897 db->db_blkid > dn->dn_maxblkid)
898 dn->dn_maxblkid = db->db_blkid;
899 dbuf_unoverride(dr);
900 } else {
901 /*
902 * This dbuf is not dirty in the open context.
903 * Either uncache it (if its not referenced in
904 * the open context) or reset its contents to
905 * empty.
906 */
907 dbuf_fix_old_data(db, txg);
908 }
909 }
910 /* clear the contents if its cached */
911 if (db->db_state == DB_CACHED) {
912 ASSERT(db->db.db_data != NULL);
913 arc_release(db->db_buf, db);
914 bzero(db->db.db_data, db->db.db_size);
915 arc_buf_freeze(db->db_buf);
916 }
917
918 mutex_exit(&db->db_mtx);
919 }
920 mutex_exit(&dn->dn_dbufs_mtx);
921 }
922
923 static int
924 dbuf_block_freeable(dmu_buf_impl_t *db)
925 {
926 dsl_dataset_t *ds = db->db_objset->os_dsl_dataset;
927 uint64_t birth_txg = 0;
928
929 /*
930 * We don't need any locking to protect db_blkptr:
931 * If it's syncing, then db_last_dirty will be set
932 * so we'll ignore db_blkptr.
933 */
934 ASSERT(MUTEX_HELD(&db->db_mtx));
935 if (db->db_last_dirty)
936 birth_txg = db->db_last_dirty->dr_txg;
937 else if (db->db_blkptr)
938 birth_txg = db->db_blkptr->blk_birth;
939
940 /*
941 * If we don't exist or are in a snapshot, we can't be freed.
942 * Don't pass the bp to dsl_dataset_block_freeable() since we
943 * are holding the db_mtx lock and might deadlock if we are
944 * prefetching a dedup-ed block.
945 */
946 if (birth_txg)
947 return (ds == NULL ||
948 dsl_dataset_block_freeable(ds, NULL, birth_txg));
949 else
950 return (FALSE);
951 }
952
953 void
954 dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx)
955 {
956 arc_buf_t *buf, *obuf;
957 int osize = db->db.db_size;
958 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
959 dnode_t *dn;
960
961 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
962
963 DB_DNODE_ENTER(db);
964 dn = DB_DNODE(db);
965
966 /* XXX does *this* func really need the lock? */
967 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
968
969 /*
970 * This call to dbuf_will_dirty() with the dn_struct_rwlock held
971 * is OK, because there can be no other references to the db
972 * when we are changing its size, so no concurrent DB_FILL can
973 * be happening.
974 */
975 /*
976 * XXX we should be doing a dbuf_read, checking the return
977 * value and returning that up to our callers
978 */
979 dbuf_will_dirty(db, tx);
980
981 /* create the data buffer for the new block */
982 buf = arc_buf_alloc(dn->dn_objset->os_spa, size, db, type);
983
984 /* copy old block data to the new block */
985 obuf = db->db_buf;
986 bcopy(obuf->b_data, buf->b_data, MIN(osize, size));
987 /* zero the remainder */
988 if (size > osize)
989 bzero((uint8_t *)buf->b_data + osize, size - osize);
990
991 mutex_enter(&db->db_mtx);
992 dbuf_set_data(db, buf);
993 VERIFY(arc_buf_remove_ref(obuf, db));
994 db->db.db_size = size;
995
996 if (db->db_level == 0) {
997 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
998 db->db_last_dirty->dt.dl.dr_data = buf;
999 }
1000 mutex_exit(&db->db_mtx);
1001
1002 dnode_willuse_space(dn, size-osize, tx);
1003 DB_DNODE_EXIT(db);
1004 }
1005
1006 void
1007 dbuf_release_bp(dmu_buf_impl_t *db)
1008 {
1009 objset_t *os;
1010
1011 DB_GET_OBJSET(&os, db);
1012 ASSERT(dsl_pool_sync_context(dmu_objset_pool(os)));
1013 ASSERT(arc_released(os->os_phys_buf) ||
1014 list_link_active(&os->os_dsl_dataset->ds_synced_link));
1015 ASSERT(db->db_parent == NULL || arc_released(db->db_parent->db_buf));
1016
1017 (void) arc_release(db->db_buf, db);
1018 }
1019
1020 dbuf_dirty_record_t *
1021 dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1022 {
1023 dnode_t *dn;
1024 objset_t *os;
1025 dbuf_dirty_record_t **drp, *dr;
1026 int drop_struct_lock = FALSE;
1027 boolean_t do_free_accounting = B_FALSE;
1028 int txgoff = tx->tx_txg & TXG_MASK;
1029
1030 ASSERT(tx->tx_txg != 0);
1031 ASSERT(!refcount_is_zero(&db->db_holds));
1032 DMU_TX_DIRTY_BUF(tx, db);
1033
1034 DB_DNODE_ENTER(db);
1035 dn = DB_DNODE(db);
1036 /*
1037 * Shouldn't dirty a regular buffer in syncing context. Private
1038 * objects may be dirtied in syncing context, but only if they
1039 * were already pre-dirtied in open context.
1040 */
1041 ASSERT(!dmu_tx_is_syncing(tx) ||
1042 BP_IS_HOLE(dn->dn_objset->os_rootbp) ||
1043 DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1044 dn->dn_objset->os_dsl_dataset == NULL);
1045 /*
1046 * We make this assert for private objects as well, but after we
1047 * check if we're already dirty. They are allowed to re-dirty
1048 * in syncing context.
1049 */
1050 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1051 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1052 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1053
1054 mutex_enter(&db->db_mtx);
1055 /*
1056 * XXX make this true for indirects too? The problem is that
1057 * transactions created with dmu_tx_create_assigned() from
1058 * syncing context don't bother holding ahead.
1059 */
1060 ASSERT(db->db_level != 0 ||
1061 db->db_state == DB_CACHED || db->db_state == DB_FILL ||
1062 db->db_state == DB_NOFILL);
1063
1064 mutex_enter(&dn->dn_mtx);
1065 /*
1066 * Don't set dirtyctx to SYNC if we're just modifying this as we
1067 * initialize the objset.
1068 */
1069 if (dn->dn_dirtyctx == DN_UNDIRTIED &&
1070 !BP_IS_HOLE(dn->dn_objset->os_rootbp)) {
1071 dn->dn_dirtyctx =
1072 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN);
1073 ASSERT(dn->dn_dirtyctx_firstset == NULL);
1074 dn->dn_dirtyctx_firstset = kmem_alloc(1, KM_SLEEP);
1075 }
1076 mutex_exit(&dn->dn_mtx);
1077
1078 if (db->db_blkid == DMU_SPILL_BLKID)
1079 dn->dn_have_spill = B_TRUE;
1080
1081 /*
1082 * If this buffer is already dirty, we're done.
1083 */
1084 drp = &db->db_last_dirty;
1085 ASSERT(*drp == NULL || (*drp)->dr_txg <= tx->tx_txg ||
1086 db->db.db_object == DMU_META_DNODE_OBJECT);
1087 while ((dr = *drp) != NULL && dr->dr_txg > tx->tx_txg)
1088 drp = &dr->dr_next;
1089 if (dr && dr->dr_txg == tx->tx_txg) {
1090 DB_DNODE_EXIT(db);
1091
1092 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID) {
1093 /*
1094 * If this buffer has already been written out,
1095 * we now need to reset its state.
1096 */
1097 dbuf_unoverride(dr);
1098 if (db->db.db_object != DMU_META_DNODE_OBJECT &&
1099 db->db_state != DB_NOFILL)
1100 arc_buf_thaw(db->db_buf);
1101 }
1102 mutex_exit(&db->db_mtx);
1103 return (dr);
1104 }
1105
1106 /*
1107 * Only valid if not already dirty.
1108 */
1109 ASSERT(dn->dn_object == 0 ||
1110 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1111 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1112
1113 ASSERT3U(dn->dn_nlevels, >, db->db_level);
1114 ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) ||
1115 dn->dn_phys->dn_nlevels > db->db_level ||
1116 dn->dn_next_nlevels[txgoff] > db->db_level ||
1117 dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level ||
1118 dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level);
1119
1120 /*
1121 * We should only be dirtying in syncing context if it's the
1122 * mos or we're initializing the os or it's a special object.
1123 * However, we are allowed to dirty in syncing context provided
1124 * we already dirtied it in open context. Hence we must make
1125 * this assertion only if we're not already dirty.
1126 */
1127 os = dn->dn_objset;
1128 ASSERT(!dmu_tx_is_syncing(tx) || DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1129 os->os_dsl_dataset == NULL || BP_IS_HOLE(os->os_rootbp));
1130 ASSERT(db->db.db_size != 0);
1131
1132 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1133
1134 if (db->db_blkid != DMU_BONUS_BLKID) {
1135 /*
1136 * Update the accounting.
1137 * Note: we delay "free accounting" until after we drop
1138 * the db_mtx. This keeps us from grabbing other locks
1139 * (and possibly deadlocking) in bp_get_dsize() while
1140 * also holding the db_mtx.
1141 */
1142 dnode_willuse_space(dn, db->db.db_size, tx);
1143 do_free_accounting = dbuf_block_freeable(db);
1144 }
1145
1146 /*
1147 * If this buffer is dirty in an old transaction group we need
1148 * to make a copy of it so that the changes we make in this
1149 * transaction group won't leak out when we sync the older txg.
1150 */
1151 dr = kmem_zalloc(sizeof (dbuf_dirty_record_t), KM_SLEEP);
1152 if (db->db_level == 0) {
1153 void *data_old = db->db_buf;
1154
1155 if (db->db_state != DB_NOFILL) {
1156 if (db->db_blkid == DMU_BONUS_BLKID) {
1157 dbuf_fix_old_data(db, tx->tx_txg);
1158 data_old = db->db.db_data;
1159 } else if (db->db.db_object != DMU_META_DNODE_OBJECT) {
1160 /*
1161 * Release the data buffer from the cache so
1162 * that we can modify it without impacting
1163 * possible other users of this cached data
1164 * block. Note that indirect blocks and
1165 * private objects are not released until the
1166 * syncing state (since they are only modified
1167 * then).
1168 */
1169 arc_release(db->db_buf, db);
1170 dbuf_fix_old_data(db, tx->tx_txg);
1171 data_old = db->db_buf;
1172 }
1173 ASSERT(data_old != NULL);
1174 }
1175 dr->dt.dl.dr_data = data_old;
1176 } else {
1177 mutex_init(&dr->dt.di.dr_mtx, NULL, MUTEX_DEFAULT, NULL);
1178 list_create(&dr->dt.di.dr_children,
1179 sizeof (dbuf_dirty_record_t),
1180 offsetof(dbuf_dirty_record_t, dr_dirty_node));
1181 }
1182 dr->dr_dbuf = db;
1183 dr->dr_txg = tx->tx_txg;
1184 dr->dr_next = *drp;
1185 *drp = dr;
1186
1187 /*
1188 * We could have been freed_in_flight between the dbuf_noread
1189 * and dbuf_dirty. We win, as though the dbuf_noread() had
1190 * happened after the free.
1191 */
1192 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
1193 db->db_blkid != DMU_SPILL_BLKID) {
1194 mutex_enter(&dn->dn_mtx);
1195 dnode_clear_range(dn, db->db_blkid, 1, tx);
1196 mutex_exit(&dn->dn_mtx);
1197 db->db_freed_in_flight = FALSE;
1198 }
1199
1200 /*
1201 * This buffer is now part of this txg
1202 */
1203 dbuf_add_ref(db, (void *)(uintptr_t)tx->tx_txg);
1204 db->db_dirtycnt += 1;
1205 ASSERT3U(db->db_dirtycnt, <=, 3);
1206
1207 mutex_exit(&db->db_mtx);
1208
1209 if (db->db_blkid == DMU_BONUS_BLKID ||
1210 db->db_blkid == DMU_SPILL_BLKID) {
1211 mutex_enter(&dn->dn_mtx);
1212 ASSERT(!list_link_active(&dr->dr_dirty_node));
1213 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1214 mutex_exit(&dn->dn_mtx);
1215 dnode_setdirty(dn, tx);
1216 DB_DNODE_EXIT(db);
1217 return (dr);
1218 } else if (do_free_accounting) {
1219 blkptr_t *bp = db->db_blkptr;
1220 int64_t willfree = (bp && !BP_IS_HOLE(bp)) ?
1221 bp_get_dsize(os->os_spa, bp) : db->db.db_size;
1222 /*
1223 * This is only a guess -- if the dbuf is dirty
1224 * in a previous txg, we don't know how much
1225 * space it will use on disk yet. We should
1226 * really have the struct_rwlock to access
1227 * db_blkptr, but since this is just a guess,
1228 * it's OK if we get an odd answer.
1229 */
1230 ddt_prefetch(os->os_spa, bp);
1231 dnode_willuse_space(dn, -willfree, tx);
1232 }
1233
1234 if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
1235 rw_enter(&dn->dn_struct_rwlock, RW_READER);
1236 drop_struct_lock = TRUE;
1237 }
1238
1239 if (db->db_level == 0) {
1240 dnode_new_blkid(dn, db->db_blkid, tx, drop_struct_lock);
1241 ASSERT(dn->dn_maxblkid >= db->db_blkid);
1242 }
1243
1244 if (db->db_level+1 < dn->dn_nlevels) {
1245 dmu_buf_impl_t *parent = db->db_parent;
1246 dbuf_dirty_record_t *di;
1247 int parent_held = FALSE;
1248
1249 if (db->db_parent == NULL || db->db_parent == dn->dn_dbuf) {
1250 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1251
1252 parent = dbuf_hold_level(dn, db->db_level+1,
1253 db->db_blkid >> epbs, FTAG);
1254 ASSERT(parent != NULL);
1255 parent_held = TRUE;
1256 }
1257 if (drop_struct_lock)
1258 rw_exit(&dn->dn_struct_rwlock);
1259 ASSERT3U(db->db_level+1, ==, parent->db_level);
1260 di = dbuf_dirty(parent, tx);
1261 if (parent_held)
1262 dbuf_rele(parent, FTAG);
1263
1264 mutex_enter(&db->db_mtx);
1265 /* possible race with dbuf_undirty() */
1266 if (db->db_last_dirty == dr ||
1267 dn->dn_object == DMU_META_DNODE_OBJECT) {
1268 mutex_enter(&di->dt.di.dr_mtx);
1269 ASSERT3U(di->dr_txg, ==, tx->tx_txg);
1270 ASSERT(!list_link_active(&dr->dr_dirty_node));
1271 list_insert_tail(&di->dt.di.dr_children, dr);
1272 mutex_exit(&di->dt.di.dr_mtx);
1273 dr->dr_parent = di;
1274 }
1275 mutex_exit(&db->db_mtx);
1276 } else {
1277 ASSERT(db->db_level+1 == dn->dn_nlevels);
1278 ASSERT(db->db_blkid < dn->dn_nblkptr);
1279 ASSERT(db->db_parent == NULL || db->db_parent == dn->dn_dbuf);
1280 mutex_enter(&dn->dn_mtx);
1281 ASSERT(!list_link_active(&dr->dr_dirty_node));
1282 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1283 mutex_exit(&dn->dn_mtx);
1284 if (drop_struct_lock)
1285 rw_exit(&dn->dn_struct_rwlock);
1286 }
1287
1288 dnode_setdirty(dn, tx);
1289 DB_DNODE_EXIT(db);
1290 return (dr);
1291 }
1292
1293 /*
1294 * Undirty a buffer in the transaction group referenced by the given
1295 * transaction. Return whether this evicted the dbuf.
1296 */
1297 static boolean_t
1298 dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1299 {
1300 dnode_t *dn;
1301 uint64_t txg = tx->tx_txg;
1302 dbuf_dirty_record_t *dr, **drp;
1303
1304 ASSERT(txg != 0);
1305 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1306 ASSERT0(db->db_level);
1307 ASSERT(MUTEX_HELD(&db->db_mtx));
1308
1309 /*
1310 * If this buffer is not dirty, we're done.
1311 */
1312 for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next)
1313 if (dr->dr_txg <= txg)
1314 break;
1315 if (dr == NULL || dr->dr_txg < txg)
1316 return (B_FALSE);
1317 ASSERT(dr->dr_txg == txg);
1318 ASSERT(dr->dr_dbuf == db);
1319
1320 DB_DNODE_ENTER(db);
1321 dn = DB_DNODE(db);
1322
1323 /*
1324 * Note: This code will probably work even if there are concurrent
1325 * holders, but it is untested in that scenerio, as the ZPL and
1326 * ztest have additional locking (the range locks) that prevents
1327 * that type of concurrent access.
1328 */
1329 ASSERT3U(refcount_count(&db->db_holds), ==, db->db_dirtycnt);
1330
1331 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1332
1333 ASSERT(db->db.db_size != 0);
1334
1335 /* XXX would be nice to fix up dn_towrite_space[] */
1336
1337 *drp = dr->dr_next;
1338
1339 /*
1340 * Note that there are three places in dbuf_dirty()
1341 * where this dirty record may be put on a list.
1342 * Make sure to do a list_remove corresponding to
1343 * every one of those list_insert calls.
1344 */
1345 if (dr->dr_parent) {
1346 mutex_enter(&dr->dr_parent->dt.di.dr_mtx);
1347 list_remove(&dr->dr_parent->dt.di.dr_children, dr);
1348 mutex_exit(&dr->dr_parent->dt.di.dr_mtx);
1349 } else if (db->db_blkid == DMU_SPILL_BLKID ||
1350 db->db_level+1 == dn->dn_nlevels) {
1351 ASSERT(db->db_blkptr == NULL || db->db_parent == dn->dn_dbuf);
1352 mutex_enter(&dn->dn_mtx);
1353 list_remove(&dn->dn_dirty_records[txg & TXG_MASK], dr);
1354 mutex_exit(&dn->dn_mtx);
1355 }
1356 DB_DNODE_EXIT(db);
1357
1358 if (db->db_state != DB_NOFILL) {
1359 dbuf_unoverride(dr);
1360
1361 ASSERT(db->db_buf != NULL);
1362 ASSERT(dr->dt.dl.dr_data != NULL);
1363 if (dr->dt.dl.dr_data != db->db_buf)
1364 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data, db));
1365 }
1366 kmem_free(dr, sizeof (dbuf_dirty_record_t));
1367
1368 ASSERT(db->db_dirtycnt > 0);
1369 db->db_dirtycnt -= 1;
1370
1371 if (refcount_remove(&db->db_holds, (void *)(uintptr_t)txg) == 0) {
1372 arc_buf_t *buf = db->db_buf;
1373
1374 ASSERT(db->db_state == DB_NOFILL || arc_released(buf));
1375 dbuf_set_data(db, NULL);
1376 VERIFY(arc_buf_remove_ref(buf, db));
1377 dbuf_evict(db);
1378 return (B_TRUE);
1379 }
1380
1381 return (B_FALSE);
1382 }
1383
1384 #pragma weak dmu_buf_will_dirty = dbuf_will_dirty
1385 void
1386 dbuf_will_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1387 {
1388 int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH;
1389
1390 ASSERT(tx->tx_txg != 0);
1391 ASSERT(!refcount_is_zero(&db->db_holds));
1392
1393 DB_DNODE_ENTER(db);
1394 if (RW_WRITE_HELD(&DB_DNODE(db)->dn_struct_rwlock))
1395 rf |= DB_RF_HAVESTRUCT;
1396 DB_DNODE_EXIT(db);
1397 (void) dbuf_read(db, NULL, rf);
1398 (void) dbuf_dirty(db, tx);
1399 }
1400
1401 void
1402 dmu_buf_will_not_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1403 {
1404 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1405
1406 db->db_state = DB_NOFILL;
1407
1408 dmu_buf_will_fill(db_fake, tx);
1409 }
1410
1411 void
1412 dmu_buf_will_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1413 {
1414 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1415
1416 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1417 ASSERT(tx->tx_txg != 0);
1418 ASSERT(db->db_level == 0);
1419 ASSERT(!refcount_is_zero(&db->db_holds));
1420
1421 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT ||
1422 dmu_tx_private_ok(tx));
1423
1424 dbuf_noread(db);
1425 (void) dbuf_dirty(db, tx);
1426 }
1427
1428 #pragma weak dmu_buf_fill_done = dbuf_fill_done
1429 /* ARGSUSED */
1430 void
1431 dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx)
1432 {
1433 mutex_enter(&db->db_mtx);
1434 DBUF_VERIFY(db);
1435
1436 if (db->db_state == DB_FILL) {
1437 if (db->db_level == 0 && db->db_freed_in_flight) {
1438 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1439 /* we were freed while filling */
1440 /* XXX dbuf_undirty? */
1441 bzero(db->db.db_data, db->db.db_size);
1442 db->db_freed_in_flight = FALSE;
1443 }
1444 db->db_state = DB_CACHED;
1445 cv_broadcast(&db->db_changed);
1446 }
1447 mutex_exit(&db->db_mtx);
1448 }
1449
1450 /*
1451 * Directly assign a provided arc buf to a given dbuf if it's not referenced
1452 * by anybody except our caller. Otherwise copy arcbuf's contents to dbuf.
1453 */
1454 void
1455 dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx)
1456 {
1457 ASSERT(!refcount_is_zero(&db->db_holds));
1458 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1459 ASSERT(db->db_level == 0);
1460 ASSERT(DBUF_GET_BUFC_TYPE(db) == ARC_BUFC_DATA);
1461 ASSERT(buf != NULL);
1462 ASSERT(arc_buf_size(buf) == db->db.db_size);
1463 ASSERT(tx->tx_txg != 0);
1464
1465 arc_return_buf(buf, db);
1466 ASSERT(arc_released(buf));
1467
1468 mutex_enter(&db->db_mtx);
1469
1470 while (db->db_state == DB_READ || db->db_state == DB_FILL)
1471 cv_wait(&db->db_changed, &db->db_mtx);
1472
1473 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED);
1474
1475 if (db->db_state == DB_CACHED &&
1476 refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) {
1477 mutex_exit(&db->db_mtx);
1478 (void) dbuf_dirty(db, tx);
1479 bcopy(buf->b_data, db->db.db_data, db->db.db_size);
1480 VERIFY(arc_buf_remove_ref(buf, db));
1481 xuio_stat_wbuf_copied();
1482 return;
1483 }
1484
1485 xuio_stat_wbuf_nocopy();
1486 if (db->db_state == DB_CACHED) {
1487 dbuf_dirty_record_t *dr = db->db_last_dirty;
1488
1489 ASSERT(db->db_buf != NULL);
1490 if (dr != NULL && dr->dr_txg == tx->tx_txg) {
1491 ASSERT(dr->dt.dl.dr_data == db->db_buf);
1492 if (!arc_released(db->db_buf)) {
1493 ASSERT(dr->dt.dl.dr_override_state ==
1494 DR_OVERRIDDEN);
1495 arc_release(db->db_buf, db);
1496 }
1497 dr->dt.dl.dr_data = buf;
1498 VERIFY(arc_buf_remove_ref(db->db_buf, db));
1499 } else if (dr == NULL || dr->dt.dl.dr_data != db->db_buf) {
1500 arc_release(db->db_buf, db);
1501 VERIFY(arc_buf_remove_ref(db->db_buf, db));
1502 }
1503 db->db_buf = NULL;
1504 }
1505 ASSERT(db->db_buf == NULL);
1506 dbuf_set_data(db, buf);
1507 db->db_state = DB_FILL;
1508 mutex_exit(&db->db_mtx);
1509 (void) dbuf_dirty(db, tx);
1510 dbuf_fill_done(db, tx);
1511 }
1512
1513 /*
1514 * "Clear" the contents of this dbuf. This will mark the dbuf
1515 * EVICTING and clear *most* of its references. Unfortunetely,
1516 * when we are not holding the dn_dbufs_mtx, we can't clear the
1517 * entry in the dn_dbufs list. We have to wait until dbuf_destroy()
1518 * in this case. For callers from the DMU we will usually see:
1519 * dbuf_clear()->arc_buf_evict()->dbuf_do_evict()->dbuf_destroy()
1520 * For the arc callback, we will usually see:
1521 * dbuf_do_evict()->dbuf_clear();dbuf_destroy()
1522 * Sometimes, though, we will get a mix of these two:
1523 * DMU: dbuf_clear()->arc_buf_evict()
1524 * ARC: dbuf_do_evict()->dbuf_destroy()
1525 */
1526 void
1527 dbuf_clear(dmu_buf_impl_t *db)
1528 {
1529 dnode_t *dn;
1530 dmu_buf_impl_t *parent = db->db_parent;
1531 dmu_buf_impl_t *dndb;
1532 int dbuf_gone = FALSE;
1533
1534 ASSERT(MUTEX_HELD(&db->db_mtx));
1535 ASSERT(refcount_is_zero(&db->db_holds));
1536
1537 dbuf_evict_user(db);
1538
1539 if (db->db_state == DB_CACHED) {
1540 ASSERT(db->db.db_data != NULL);
1541 if (db->db_blkid == DMU_BONUS_BLKID) {
1542 zio_buf_free(db->db.db_data, DN_MAX_BONUSLEN);
1543 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
1544 }
1545 db->db.db_data = NULL;
1546 db->db_state = DB_UNCACHED;
1547 }
1548
1549 ASSERT(db->db_state == DB_UNCACHED || db->db_state == DB_NOFILL);
1550 ASSERT(db->db_data_pending == NULL);
1551
1552 db->db_state = DB_EVICTING;
1553 db->db_blkptr = NULL;
1554
1555 DB_DNODE_ENTER(db);
1556 dn = DB_DNODE(db);
1557 dndb = dn->dn_dbuf;
1558 if (db->db_blkid != DMU_BONUS_BLKID && MUTEX_HELD(&dn->dn_dbufs_mtx)) {
1559 list_remove(&dn->dn_dbufs, db);
1560 (void) atomic_dec_32_nv(&dn->dn_dbufs_count);
1561 membar_producer();
1562 DB_DNODE_EXIT(db);
1563 /*
1564 * Decrementing the dbuf count means that the hold corresponding
1565 * to the removed dbuf is no longer discounted in dnode_move(),
1566 * so the dnode cannot be moved until after we release the hold.
1567 * The membar_producer() ensures visibility of the decremented
1568 * value in dnode_move(), since DB_DNODE_EXIT doesn't actually
1569 * release any lock.
1570 */
1571 dnode_rele(dn, db);
1572 db->db_dnode_handle = NULL;
1573 } else {
1574 DB_DNODE_EXIT(db);
1575 }
1576
1577 if (db->db_buf)
1578 dbuf_gone = arc_buf_evict(db->db_buf);
1579
1580 if (!dbuf_gone)
1581 mutex_exit(&db->db_mtx);
1582
1583 /*
1584 * If this dbuf is referenced from an indirect dbuf,
1585 * decrement the ref count on the indirect dbuf.
1586 */
1587 if (parent && parent != dndb)
1588 dbuf_rele(parent, db);
1589 }
1590
1591 static int
1592 dbuf_findbp(dnode_t *dn, int level, uint64_t blkid, int fail_sparse,
1593 dmu_buf_impl_t **parentp, blkptr_t **bpp)
1594 {
1595 int nlevels, epbs;
1596
1597 *parentp = NULL;
1598 *bpp = NULL;
1599
1600 ASSERT(blkid != DMU_BONUS_BLKID);
1601
1602 if (blkid == DMU_SPILL_BLKID) {
1603 mutex_enter(&dn->dn_mtx);
1604 if (dn->dn_have_spill &&
1605 (dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR))
1606 *bpp = &dn->dn_phys->dn_spill;
1607 else
1608 *bpp = NULL;
1609 dbuf_add_ref(dn->dn_dbuf, NULL);
1610 *parentp = dn->dn_dbuf;
1611 mutex_exit(&dn->dn_mtx);
1612 return (0);
1613 }
1614
1615 if (dn->dn_phys->dn_nlevels == 0)
1616 nlevels = 1;
1617 else
1618 nlevels = dn->dn_phys->dn_nlevels;
1619
1620 epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1621
1622 ASSERT3U(level * epbs, <, 64);
1623 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1624 if (level >= nlevels ||
1625 (blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))) {
1626 /* the buffer has no parent yet */
1627 return (SET_ERROR(ENOENT));
1628 } else if (level < nlevels-1) {
1629 /* this block is referenced from an indirect block */
1630 int err = dbuf_hold_impl(dn, level+1,
1631 blkid >> epbs, fail_sparse, NULL, parentp);
1632 if (err)
1633 return (err);
1634 err = dbuf_read(*parentp, NULL,
1635 (DB_RF_HAVESTRUCT | DB_RF_NOPREFETCH | DB_RF_CANFAIL));
1636 if (err) {
1637 dbuf_rele(*parentp, NULL);
1638 *parentp = NULL;
1639 return (err);
1640 }
1641 *bpp = ((blkptr_t *)(*parentp)->db.db_data) +
1642 (blkid & ((1ULL << epbs) - 1));
1643 return (0);
1644 } else {
1645 /* the block is referenced from the dnode */
1646 ASSERT3U(level, ==, nlevels-1);
1647 ASSERT(dn->dn_phys->dn_nblkptr == 0 ||
1648 blkid < dn->dn_phys->dn_nblkptr);
1649 if (dn->dn_dbuf) {
1650 dbuf_add_ref(dn->dn_dbuf, NULL);
1651 *parentp = dn->dn_dbuf;
1652 }
1653 *bpp = &dn->dn_phys->dn_blkptr[blkid];
1654 return (0);
1655 }
1656 }
1657
1658 static dmu_buf_impl_t *
1659 dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid,
1660 dmu_buf_impl_t *parent, blkptr_t *blkptr)
1661 {
1662 objset_t *os = dn->dn_objset;
1663 dmu_buf_impl_t *db, *odb;
1664
1665 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1666 ASSERT(dn->dn_type != DMU_OT_NONE);
1667
1668 db = kmem_cache_alloc(dbuf_cache, KM_SLEEP);
1669
1670 db->db_objset = os;
1671 db->db.db_object = dn->dn_object;
1672 db->db_level = level;
1673 db->db_blkid = blkid;
1674 db->db_last_dirty = NULL;
1675 db->db_dirtycnt = 0;
1676 db->db_dnode_handle = dn->dn_handle;
1677 db->db_parent = parent;
1678 db->db_blkptr = blkptr;
1679
1680 db->db_user_ptr = NULL;
1681 db->db_user_data_ptr_ptr = NULL;
1682 db->db_evict_func = NULL;
1683 db->db_immediate_evict = 0;
1684 db->db_freed_in_flight = 0;
1685
1686 if (blkid == DMU_BONUS_BLKID) {
1687 ASSERT3P(parent, ==, dn->dn_dbuf);
1688 db->db.db_size = DN_MAX_BONUSLEN -
1689 (dn->dn_nblkptr-1) * sizeof (blkptr_t);
1690 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
1691 db->db.db_offset = DMU_BONUS_BLKID;
1692 db->db_state = DB_UNCACHED;
1693 /* the bonus dbuf is not placed in the hash table */
1694 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1695 return (db);
1696 } else if (blkid == DMU_SPILL_BLKID) {
1697 db->db.db_size = (blkptr != NULL) ?
1698 BP_GET_LSIZE(blkptr) : SPA_MINBLOCKSIZE;
1699 db->db.db_offset = 0;
1700 } else {
1701 int blocksize =
1702 db->db_level ? 1<<dn->dn_indblkshift : dn->dn_datablksz;
1703 db->db.db_size = blocksize;
1704 db->db.db_offset = db->db_blkid * blocksize;
1705 }
1706
1707 /*
1708 * Hold the dn_dbufs_mtx while we get the new dbuf
1709 * in the hash table *and* added to the dbufs list.
1710 * This prevents a possible deadlock with someone
1711 * trying to look up this dbuf before its added to the
1712 * dn_dbufs list.
1713 */
1714 mutex_enter(&dn->dn_dbufs_mtx);
1715 db->db_state = DB_EVICTING;
1716 if ((odb = dbuf_hash_insert(db)) != NULL) {
1717 /* someone else inserted it first */
1718 kmem_cache_free(dbuf_cache, db);
1719 mutex_exit(&dn->dn_dbufs_mtx);
1720 return (odb);
1721 }
1722 list_insert_head(&dn->dn_dbufs, db);
1723 db->db_state = DB_UNCACHED;
1724 mutex_exit(&dn->dn_dbufs_mtx);
1725 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1726
1727 if (parent && parent != dn->dn_dbuf)
1728 dbuf_add_ref(parent, db);
1729
1730 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1731 refcount_count(&dn->dn_holds) > 0);
1732 (void) refcount_add(&dn->dn_holds, db);
1733 (void) atomic_inc_32_nv(&dn->dn_dbufs_count);
1734
1735 dprintf_dbuf(db, "db=%p\n", db);
1736
1737 return (db);
1738 }
1739
1740 static int
1741 dbuf_do_evict(void *private)
1742 {
1743 arc_buf_t *buf = private;
1744 dmu_buf_impl_t *db = buf->b_private;
1745
1746 if (!MUTEX_HELD(&db->db_mtx))
1747 mutex_enter(&db->db_mtx);
1748
1749 ASSERT(refcount_is_zero(&db->db_holds));
1750
1751 if (db->db_state != DB_EVICTING) {
1752 ASSERT(db->db_state == DB_CACHED);
1753 DBUF_VERIFY(db);
1754 db->db_buf = NULL;
1755 dbuf_evict(db);
1756 } else {
1757 mutex_exit(&db->db_mtx);
1758 dbuf_destroy(db);
1759 }
1760 return (0);
1761 }
1762
1763 static void
1764 dbuf_destroy(dmu_buf_impl_t *db)
1765 {
1766 ASSERT(refcount_is_zero(&db->db_holds));
1767
1768 if (db->db_blkid != DMU_BONUS_BLKID) {
1769 /*
1770 * If this dbuf is still on the dn_dbufs list,
1771 * remove it from that list.
1772 */
1773 if (db->db_dnode_handle != NULL) {
1774 dnode_t *dn;
1775
1776 DB_DNODE_ENTER(db);
1777 dn = DB_DNODE(db);
1778 mutex_enter(&dn->dn_dbufs_mtx);
1779 list_remove(&dn->dn_dbufs, db);
1780 (void) atomic_dec_32_nv(&dn->dn_dbufs_count);
1781 mutex_exit(&dn->dn_dbufs_mtx);
1782 DB_DNODE_EXIT(db);
1783 /*
1784 * Decrementing the dbuf count means that the hold
1785 * corresponding to the removed dbuf is no longer
1786 * discounted in dnode_move(), so the dnode cannot be
1787 * moved until after we release the hold.
1788 */
1789 dnode_rele(dn, db);
1790 db->db_dnode_handle = NULL;
1791 }
1792 dbuf_hash_remove(db);
1793 }
1794 db->db_parent = NULL;
1795 db->db_buf = NULL;
1796
1797 ASSERT(!list_link_active(&db->db_link));
1798 ASSERT(db->db.db_data == NULL);
1799 ASSERT(db->db_hash_next == NULL);
1800 ASSERT(db->db_blkptr == NULL);
1801 ASSERT(db->db_data_pending == NULL);
1802
1803 kmem_cache_free(dbuf_cache, db);
1804 arc_space_return(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1805 }
1806
1807 void
1808 dbuf_prefetch(dnode_t *dn, uint64_t blkid)
1809 {
1810 dmu_buf_impl_t *db = NULL;
1811 blkptr_t *bp = NULL;
1812
1813 ASSERT(blkid != DMU_BONUS_BLKID);
1814 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1815
1816 if (dnode_block_freed(dn, blkid))
1817 return;
1818
1819 /* dbuf_find() returns with db_mtx held */
1820 if (db = dbuf_find(dn, 0, blkid)) {
1821 /*
1822 * This dbuf is already in the cache. We assume that
1823 * it is already CACHED, or else about to be either
1824 * read or filled.
1825 */
1826 mutex_exit(&db->db_mtx);
1827 return;
1828 }
1829
1830 if (dbuf_findbp(dn, 0, blkid, TRUE, &db, &bp) == 0) {
1831 if (bp && !BP_IS_HOLE(bp)) {
1832 int priority = dn->dn_type == DMU_OT_DDT_ZAP ?
1833 ZIO_PRIORITY_DDT_PREFETCH : ZIO_PRIORITY_ASYNC_READ;
1834 dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset;
1835 uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH;
1836 zbookmark_t zb;
1837
1838 SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
1839 dn->dn_object, 0, blkid);
1840
1841 (void) arc_read(NULL, dn->dn_objset->os_spa,
1842 bp, NULL, NULL, priority,
1843 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
1844 &aflags, &zb);
1845 }
1846 if (db)
1847 dbuf_rele(db, NULL);
1848 }
1849 }
1850
1851 /*
1852 * Returns with db_holds incremented, and db_mtx not held.
1853 * Note: dn_struct_rwlock must be held.
1854 */
1855 int
1856 dbuf_hold_impl(dnode_t *dn, uint8_t level, uint64_t blkid, int fail_sparse,
1857 void *tag, dmu_buf_impl_t **dbp)
1858 {
1859 dmu_buf_impl_t *db, *parent = NULL;
1860
1861 ASSERT(blkid != DMU_BONUS_BLKID);
1862 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1863 ASSERT3U(dn->dn_nlevels, >, level);
1864
1865 *dbp = NULL;
1866 top:
1867 /* dbuf_find() returns with db_mtx held */
1868 db = dbuf_find(dn, level, blkid);
1869
1870 if (db == NULL) {
1871 blkptr_t *bp = NULL;
1872 int err;
1873
1874 ASSERT3P(parent, ==, NULL);
1875 err = dbuf_findbp(dn, level, blkid, fail_sparse, &parent, &bp);
1876 if (fail_sparse) {
1877 if (err == 0 && bp && BP_IS_HOLE(bp))
1878 err = SET_ERROR(ENOENT);
1879 if (err) {
1880 if (parent)
1881 dbuf_rele(parent, NULL);
1882 return (err);
1883 }
1884 }
1885 if (err && err != ENOENT)
1886 return (err);
1887 db = dbuf_create(dn, level, blkid, parent, bp);
1888 }
1889
1890 if (db->db_buf && refcount_is_zero(&db->db_holds)) {
1891 arc_buf_add_ref(db->db_buf, db);
1892 if (db->db_buf->b_data == NULL) {
1893 dbuf_clear(db);
1894 if (parent) {
1895 dbuf_rele(parent, NULL);
1896 parent = NULL;
1897 }
1898 goto top;
1899 }
1900 ASSERT3P(db->db.db_data, ==, db->db_buf->b_data);
1901 }
1902
1903 ASSERT(db->db_buf == NULL || arc_referenced(db->db_buf));
1904
1905 /*
1906 * If this buffer is currently syncing out, and we are are
1907 * still referencing it from db_data, we need to make a copy
1908 * of it in case we decide we want to dirty it again in this txg.
1909 */
1910 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
1911 dn->dn_object != DMU_META_DNODE_OBJECT &&
1912 db->db_state == DB_CACHED && db->db_data_pending) {
1913 dbuf_dirty_record_t *dr = db->db_data_pending;
1914
1915 if (dr->dt.dl.dr_data == db->db_buf) {
1916 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
1917
1918 dbuf_set_data(db,
1919 arc_buf_alloc(dn->dn_objset->os_spa,
1920 db->db.db_size, db, type));
1921 bcopy(dr->dt.dl.dr_data->b_data, db->db.db_data,
1922 db->db.db_size);
1923 }
1924 }
1925
1926 (void) refcount_add(&db->db_holds, tag);
1927 dbuf_update_data(db);
1928 DBUF_VERIFY(db);
1929 mutex_exit(&db->db_mtx);
1930
1931 /* NOTE: we can't rele the parent until after we drop the db_mtx */
1932 if (parent)
1933 dbuf_rele(parent, NULL);
1934
1935 ASSERT3P(DB_DNODE(db), ==, dn);
1936 ASSERT3U(db->db_blkid, ==, blkid);
1937 ASSERT3U(db->db_level, ==, level);
1938 *dbp = db;
1939
1940 return (0);
1941 }
1942
1943 dmu_buf_impl_t *
1944 dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag)
1945 {
1946 dmu_buf_impl_t *db;
1947 int err = dbuf_hold_impl(dn, 0, blkid, FALSE, tag, &db);
1948 return (err ? NULL : db);
1949 }
1950
1951 dmu_buf_impl_t *
1952 dbuf_hold_level(dnode_t *dn, int level, uint64_t blkid, void *tag)
1953 {
1954 dmu_buf_impl_t *db;
1955 int err = dbuf_hold_impl(dn, level, blkid, FALSE, tag, &db);
1956 return (err ? NULL : db);
1957 }
1958
1959 void
1960 dbuf_create_bonus(dnode_t *dn)
1961 {
1962 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
1963
1964 ASSERT(dn->dn_bonus == NULL);
1965 dn->dn_bonus = dbuf_create(dn, 0, DMU_BONUS_BLKID, dn->dn_dbuf, NULL);
1966 }
1967
1968 int
1969 dbuf_spill_set_blksz(dmu_buf_t *db_fake, uint64_t blksz, dmu_tx_t *tx)
1970 {
1971 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1972 dnode_t *dn;
1973
1974 if (db->db_blkid != DMU_SPILL_BLKID)
1975 return (SET_ERROR(ENOTSUP));
1976 if (blksz == 0)
1977 blksz = SPA_MINBLOCKSIZE;
1978 if (blksz > SPA_MAXBLOCKSIZE)
1979 blksz = SPA_MAXBLOCKSIZE;
1980 else
1981 blksz = P2ROUNDUP(blksz, SPA_MINBLOCKSIZE);
1982
1983 DB_DNODE_ENTER(db);
1984 dn = DB_DNODE(db);
1985 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
1986 dbuf_new_size(db, blksz, tx);
1987 rw_exit(&dn->dn_struct_rwlock);
1988 DB_DNODE_EXIT(db);
1989
1990 return (0);
1991 }
1992
1993 void
1994 dbuf_rm_spill(dnode_t *dn, dmu_tx_t *tx)
1995 {
1996 dbuf_free_range(dn, DMU_SPILL_BLKID, DMU_SPILL_BLKID, tx);
1997 }
1998
1999 #pragma weak dmu_buf_add_ref = dbuf_add_ref
2000 void
2001 dbuf_add_ref(dmu_buf_impl_t *db, void *tag)
2002 {
2003 int64_t holds = refcount_add(&db->db_holds, tag);
2004 ASSERT(holds > 1);
2005 }
2006
2007 /*
2008 * If you call dbuf_rele() you had better not be referencing the dnode handle
2009 * unless you have some other direct or indirect hold on the dnode. (An indirect
2010 * hold is a hold on one of the dnode's dbufs, including the bonus buffer.)
2011 * Without that, the dbuf_rele() could lead to a dnode_rele() followed by the
2012 * dnode's parent dbuf evicting its dnode handles.
2013 */
2014 #pragma weak dmu_buf_rele = dbuf_rele
2015 void
2016 dbuf_rele(dmu_buf_impl_t *db, void *tag)
2017 {
2018 mutex_enter(&db->db_mtx);
2019 dbuf_rele_and_unlock(db, tag);
2020 }
2021
2022 /*
2023 * dbuf_rele() for an already-locked dbuf. This is necessary to allow
2024 * db_dirtycnt and db_holds to be updated atomically.
2025 */
2026 void
2027 dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag)
2028 {
2029 int64_t holds;
2030
2031 ASSERT(MUTEX_HELD(&db->db_mtx));
2032 DBUF_VERIFY(db);
2033
2034 /*
2035 * Remove the reference to the dbuf before removing its hold on the
2036 * dnode so we can guarantee in dnode_move() that a referenced bonus
2037 * buffer has a corresponding dnode hold.
2038 */
2039 holds = refcount_remove(&db->db_holds, tag);
2040 ASSERT(holds >= 0);
2041
2042 /*
2043 * We can't freeze indirects if there is a possibility that they
2044 * may be modified in the current syncing context.
2045 */
2046 if (db->db_buf && holds == (db->db_level == 0 ? db->db_dirtycnt : 0))
2047 arc_buf_freeze(db->db_buf);
2048
2049 if (holds == db->db_dirtycnt &&
2050 db->db_level == 0 && db->db_immediate_evict)
2051 dbuf_evict_user(db);
2052
2053 if (holds == 0) {
2054 if (db->db_blkid == DMU_BONUS_BLKID) {
2055 mutex_exit(&db->db_mtx);
2056
2057 /*
2058 * If the dnode moves here, we cannot cross this barrier
2059 * until the move completes.
2060 */
2061 DB_DNODE_ENTER(db);
2062 (void) atomic_dec_32_nv(&DB_DNODE(db)->dn_dbufs_count);
2063 DB_DNODE_EXIT(db);
2064 /*
2065 * The bonus buffer's dnode hold is no longer discounted
2066 * in dnode_move(). The dnode cannot move until after
2067 * the dnode_rele().
2068 */
2069 dnode_rele(DB_DNODE(db), db);
2070 } else if (db->db_buf == NULL) {
2071 /*
2072 * This is a special case: we never associated this
2073 * dbuf with any data allocated from the ARC.
2074 */
2075 ASSERT(db->db_state == DB_UNCACHED ||
2076 db->db_state == DB_NOFILL);
2077 dbuf_evict(db);
2078 } else if (arc_released(db->db_buf)) {
2079 arc_buf_t *buf = db->db_buf;
2080 /*
2081 * This dbuf has anonymous data associated with it.
2082 */
2083 dbuf_set_data(db, NULL);
2084 VERIFY(arc_buf_remove_ref(buf, db));
2085 dbuf_evict(db);
2086 } else {
2087 VERIFY(!arc_buf_remove_ref(db->db_buf, db));
2088
2089 /*
2090 * A dbuf will be eligible for eviction if either the
2091 * 'primarycache' property is set or a duplicate
2092 * copy of this buffer is already cached in the arc.
2093 *
2094 * In the case of the 'primarycache' a buffer
2095 * is considered for eviction if it matches the
2096 * criteria set in the property.
2097 *
2098 * To decide if our buffer is considered a
2099 * duplicate, we must call into the arc to determine
2100 * if multiple buffers are referencing the same
2101 * block on-disk. If so, then we simply evict
2102 * ourselves.
2103 */
2104 if (!DBUF_IS_CACHEABLE(db) ||
2105 arc_buf_eviction_needed(db->db_buf))
2106 dbuf_clear(db);
2107 else
2108 mutex_exit(&db->db_mtx);
2109 }
2110 } else {
2111 mutex_exit(&db->db_mtx);
2112 }
2113 }
2114
2115 #pragma weak dmu_buf_refcount = dbuf_refcount
2116 uint64_t
2117 dbuf_refcount(dmu_buf_impl_t *db)
2118 {
2119 return (refcount_count(&db->db_holds));
2120 }
2121
2122 void *
2123 dmu_buf_set_user(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr,
2124 dmu_buf_evict_func_t *evict_func)
2125 {
2126 return (dmu_buf_update_user(db_fake, NULL, user_ptr,
2127 user_data_ptr_ptr, evict_func));
2128 }
2129
2130 void *
2131 dmu_buf_set_user_ie(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr,
2132 dmu_buf_evict_func_t *evict_func)
2133 {
2134 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2135
2136 db->db_immediate_evict = TRUE;
2137 return (dmu_buf_update_user(db_fake, NULL, user_ptr,
2138 user_data_ptr_ptr, evict_func));
2139 }
2140
2141 void *
2142 dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr, void *user_ptr,
2143 void *user_data_ptr_ptr, dmu_buf_evict_func_t *evict_func)
2144 {
2145 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2146 ASSERT(db->db_level == 0);
2147
2148 ASSERT((user_ptr == NULL) == (evict_func == NULL));
2149
2150 mutex_enter(&db->db_mtx);
2151
2152 if (db->db_user_ptr == old_user_ptr) {
2153 db->db_user_ptr = user_ptr;
2154 db->db_user_data_ptr_ptr = user_data_ptr_ptr;
2155 db->db_evict_func = evict_func;
2156
2157 dbuf_update_data(db);
2158 } else {
2159 old_user_ptr = db->db_user_ptr;
2160 }
2161
2162 mutex_exit(&db->db_mtx);
2163 return (old_user_ptr);
2164 }
2165
2166 void *
2167 dmu_buf_get_user(dmu_buf_t *db_fake)
2168 {
2169 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2170 ASSERT(!refcount_is_zero(&db->db_holds));
2171
2172 return (db->db_user_ptr);
2173 }
2174
2175 boolean_t
2176 dmu_buf_freeable(dmu_buf_t *dbuf)
2177 {
2178 boolean_t res = B_FALSE;
2179 dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf;
2180
2181 if (db->db_blkptr)
2182 res = dsl_dataset_block_freeable(db->db_objset->os_dsl_dataset,
2183 db->db_blkptr, db->db_blkptr->blk_birth);
2184
2185 return (res);
2186 }
2187
2188 blkptr_t *
2189 dmu_buf_get_blkptr(dmu_buf_t *db)
2190 {
2191 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
2192 return (dbi->db_blkptr);
2193 }
2194
2195 static void
2196 dbuf_check_blkptr(dnode_t *dn, dmu_buf_impl_t *db)
2197 {
2198 /* ASSERT(dmu_tx_is_syncing(tx) */
2199 ASSERT(MUTEX_HELD(&db->db_mtx));
2200
2201 if (db->db_blkptr != NULL)
2202 return;
2203
2204 if (db->db_blkid == DMU_SPILL_BLKID) {
2205 db->db_blkptr = &dn->dn_phys->dn_spill;
2206 BP_ZERO(db->db_blkptr);
2207 return;
2208 }
2209 if (db->db_level == dn->dn_phys->dn_nlevels-1) {
2210 /*
2211 * This buffer was allocated at a time when there was
2212 * no available blkptrs from the dnode, or it was
2213 * inappropriate to hook it in (i.e., nlevels mis-match).
2214 */
2215 ASSERT(db->db_blkid < dn->dn_phys->dn_nblkptr);
2216 ASSERT(db->db_parent == NULL);
2217 db->db_parent = dn->dn_dbuf;
2218 db->db_blkptr = &dn->dn_phys->dn_blkptr[db->db_blkid];
2219 DBUF_VERIFY(db);
2220 } else {
2221 dmu_buf_impl_t *parent = db->db_parent;
2222 int epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2223
2224 ASSERT(dn->dn_phys->dn_nlevels > 1);
2225 if (parent == NULL) {
2226 mutex_exit(&db->db_mtx);
2227 rw_enter(&dn->dn_struct_rwlock, RW_READER);
2228 (void) dbuf_hold_impl(dn, db->db_level+1,
2229 db->db_blkid >> epbs, FALSE, db, &parent);
2230 rw_exit(&dn->dn_struct_rwlock);
2231 mutex_enter(&db->db_mtx);
2232 db->db_parent = parent;
2233 }
2234 db->db_blkptr = (blkptr_t *)parent->db.db_data +
2235 (db->db_blkid & ((1ULL << epbs) - 1));
2236 DBUF_VERIFY(db);
2237 }
2238 }
2239
2240 static void
2241 dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
2242 {
2243 dmu_buf_impl_t *db = dr->dr_dbuf;
2244 dnode_t *dn;
2245 zio_t *zio;
2246
2247 ASSERT(dmu_tx_is_syncing(tx));
2248
2249 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
2250
2251 mutex_enter(&db->db_mtx);
2252
2253 ASSERT(db->db_level > 0);
2254 DBUF_VERIFY(db);
2255
2256 /* Read the block if it hasn't been read yet. */
2257 if (db->db_buf == NULL) {
2258 mutex_exit(&db->db_mtx);
2259 (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED);
2260 mutex_enter(&db->db_mtx);
2261 }
2262 ASSERT3U(db->db_state, ==, DB_CACHED);
2263 ASSERT(db->db_buf != NULL);
2264
2265 DB_DNODE_ENTER(db);
2266 dn = DB_DNODE(db);
2267 /* Indirect block size must match what the dnode thinks it is. */
2268 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2269 dbuf_check_blkptr(dn, db);
2270 DB_DNODE_EXIT(db);
2271
2272 /* Provide the pending dirty record to child dbufs */
2273 db->db_data_pending = dr;
2274
2275 mutex_exit(&db->db_mtx);
2276 dbuf_write(dr, db->db_buf, tx);
2277
2278 zio = dr->dr_zio;
2279 mutex_enter(&dr->dt.di.dr_mtx);
2280 dbuf_sync_list(&dr->dt.di.dr_children, tx);
2281 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
2282 mutex_exit(&dr->dt.di.dr_mtx);
2283 zio_nowait(zio);
2284 }
2285
2286 static void
2287 dbuf_sync_leaf(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
2288 {
2289 arc_buf_t **datap = &dr->dt.dl.dr_data;
2290 dmu_buf_impl_t *db = dr->dr_dbuf;
2291 dnode_t *dn;
2292 objset_t *os;
2293 uint64_t txg = tx->tx_txg;
2294
2295 ASSERT(dmu_tx_is_syncing(tx));
2296
2297 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
2298
2299 mutex_enter(&db->db_mtx);
2300 /*
2301 * To be synced, we must be dirtied. But we
2302 * might have been freed after the dirty.
2303 */
2304 if (db->db_state == DB_UNCACHED) {
2305 /* This buffer has been freed since it was dirtied */
2306 ASSERT(db->db.db_data == NULL);
2307 } else if (db->db_state == DB_FILL) {
2308 /* This buffer was freed and is now being re-filled */
2309 ASSERT(db->db.db_data != dr->dt.dl.dr_data);
2310 } else {
2311 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_NOFILL);
2312 }
2313 DBUF_VERIFY(db);
2314
2315 DB_DNODE_ENTER(db);
2316 dn = DB_DNODE(db);
2317
2318 if (db->db_blkid == DMU_SPILL_BLKID) {
2319 mutex_enter(&dn->dn_mtx);
2320 dn->dn_phys->dn_flags |= DNODE_FLAG_SPILL_BLKPTR;
2321 mutex_exit(&dn->dn_mtx);
2322 }
2323
2324 /*
2325 * If this is a bonus buffer, simply copy the bonus data into the
2326 * dnode. It will be written out when the dnode is synced (and it
2327 * will be synced, since it must have been dirty for dbuf_sync to
2328 * be called).
2329 */
2330 if (db->db_blkid == DMU_BONUS_BLKID) {
2331 dbuf_dirty_record_t **drp;
2332
2333 ASSERT(*datap != NULL);
2334 ASSERT0(db->db_level);
2335 ASSERT3U(dn->dn_phys->dn_bonuslen, <=, DN_MAX_BONUSLEN);
2336 bcopy(*datap, DN_BONUS(dn->dn_phys), dn->dn_phys->dn_bonuslen);
2337 DB_DNODE_EXIT(db);
2338
2339 if (*datap != db->db.db_data) {
2340 zio_buf_free(*datap, DN_MAX_BONUSLEN);
2341 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
2342 }
2343 db->db_data_pending = NULL;
2344 drp = &db->db_last_dirty;
2345 while (*drp != dr)
2346 drp = &(*drp)->dr_next;
2347 ASSERT(dr->dr_next == NULL);
2348 ASSERT(dr->dr_dbuf == db);
2349 *drp = dr->dr_next;
2350 kmem_free(dr, sizeof (dbuf_dirty_record_t));
2351 ASSERT(db->db_dirtycnt > 0);
2352 db->db_dirtycnt -= 1;
2353 dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg);
2354 return;
2355 }
2356
2357 os = dn->dn_objset;
2358
2359 /*
2360 * This function may have dropped the db_mtx lock allowing a dmu_sync
2361 * operation to sneak in. As a result, we need to ensure that we
2362 * don't check the dr_override_state until we have returned from
2363 * dbuf_check_blkptr.
2364 */
2365 dbuf_check_blkptr(dn, db);
2366
2367 /*
2368 * If this buffer is in the middle of an immediate write,
2369 * wait for the synchronous IO to complete.
2370 */
2371 while (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC) {
2372 ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
2373 cv_wait(&db->db_changed, &db->db_mtx);
2374 ASSERT(dr->dt.dl.dr_override_state != DR_NOT_OVERRIDDEN);
2375 }
2376
2377 if (db->db_state != DB_NOFILL &&
2378 dn->dn_object != DMU_META_DNODE_OBJECT &&
2379 refcount_count(&db->db_holds) > 1 &&
2380 dr->dt.dl.dr_override_state != DR_OVERRIDDEN &&
2381 *datap == db->db_buf) {
2382 /*
2383 * If this buffer is currently "in use" (i.e., there
2384 * are active holds and db_data still references it),
2385 * then make a copy before we start the write so that
2386 * any modifications from the open txg will not leak
2387 * into this write.
2388 *
2389 * NOTE: this copy does not need to be made for
2390 * objects only modified in the syncing context (e.g.
2391 * DNONE_DNODE blocks).
2392 */
2393 int blksz = arc_buf_size(*datap);
2394 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
2395 *datap = arc_buf_alloc(os->os_spa, blksz, db, type);
2396 bcopy(db->db.db_data, (*datap)->b_data, blksz);
2397 }
2398 db->db_data_pending = dr;
2399
2400 mutex_exit(&db->db_mtx);
2401
2402 dbuf_write(dr, *datap, tx);
2403
2404 ASSERT(!list_link_active(&dr->dr_dirty_node));
2405 if (dn->dn_object == DMU_META_DNODE_OBJECT) {
2406 list_insert_tail(&dn->dn_dirty_records[txg&TXG_MASK], dr);
2407 DB_DNODE_EXIT(db);
2408 } else {
2409 /*
2410 * Although zio_nowait() does not "wait for an IO", it does
2411 * initiate the IO. If this is an empty write it seems plausible
2412 * that the IO could actually be completed before the nowait
2413 * returns. We need to DB_DNODE_EXIT() first in case
2414 * zio_nowait() invalidates the dbuf.
2415 */
2416 DB_DNODE_EXIT(db);
2417 zio_nowait(dr->dr_zio);
2418 }
2419 }
2420
2421 void
2422 dbuf_sync_list(list_t *list, dmu_tx_t *tx)
2423 {
2424 dbuf_dirty_record_t *dr;
2425
2426 while (dr = list_head(list)) {
2427 if (dr->dr_zio != NULL) {
2428 /*
2429 * If we find an already initialized zio then we
2430 * are processing the meta-dnode, and we have finished.
2431 * The dbufs for all dnodes are put back on the list
2432 * during processing, so that we can zio_wait()
2433 * these IOs after initiating all child IOs.
2434 */
2435 ASSERT3U(dr->dr_dbuf->db.db_object, ==,
2436 DMU_META_DNODE_OBJECT);
2437 break;
2438 }
2439 list_remove(list, dr);
2440 if (dr->dr_dbuf->db_level > 0)
2441 dbuf_sync_indirect(dr, tx);
2442 else
2443 dbuf_sync_leaf(dr, tx);
2444 }
2445 }
2446
2447 /* ARGSUSED */
2448 static void
2449 dbuf_write_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
2450 {
2451 dmu_buf_impl_t *db = vdb;
2452 dnode_t *dn;
2453 blkptr_t *bp = zio->io_bp;
2454 blkptr_t *bp_orig = &zio->io_bp_orig;
2455 spa_t *spa = zio->io_spa;
2456 int64_t delta;
2457 uint64_t fill = 0;
2458 int i;
2459
2460 ASSERT(db->db_blkptr == bp);
2461
2462 DB_DNODE_ENTER(db);
2463 dn = DB_DNODE(db);
2464 delta = bp_get_dsize_sync(spa, bp) - bp_get_dsize_sync(spa, bp_orig);
2465 dnode_diduse_space(dn, delta - zio->io_prev_space_delta);
2466 zio->io_prev_space_delta = delta;
2467
2468 if (BP_IS_HOLE(bp)) {
2469 ASSERT(bp->blk_fill == 0);
2470 DB_DNODE_EXIT(db);
2471 return;
2472 }
2473
2474 ASSERT((db->db_blkid != DMU_SPILL_BLKID &&
2475 BP_GET_TYPE(bp) == dn->dn_type) ||
2476 (db->db_blkid == DMU_SPILL_BLKID &&
2477 BP_GET_TYPE(bp) == dn->dn_bonustype));
2478 ASSERT(BP_GET_LEVEL(bp) == db->db_level);
2479
2480 mutex_enter(&db->db_mtx);
2481
2482 #ifdef ZFS_DEBUG
2483 if (db->db_blkid == DMU_SPILL_BLKID) {
2484 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
2485 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
2486 db->db_blkptr == &dn->dn_phys->dn_spill);
2487 }
2488 #endif
2489
2490 if (db->db_level == 0) {
2491 mutex_enter(&dn->dn_mtx);
2492 if (db->db_blkid > dn->dn_phys->dn_maxblkid &&
2493 db->db_blkid != DMU_SPILL_BLKID)
2494 dn->dn_phys->dn_maxblkid = db->db_blkid;
2495 mutex_exit(&dn->dn_mtx);
2496
2497 if (dn->dn_type == DMU_OT_DNODE) {
2498 dnode_phys_t *dnp = db->db.db_data;
2499 for (i = db->db.db_size >> DNODE_SHIFT; i > 0;
2500 i--, dnp++) {
2501 if (dnp->dn_type != DMU_OT_NONE)
2502 fill++;
2503 }
2504 } else {
2505 fill = 1;
2506 }
2507 } else {
2508 blkptr_t *ibp = db->db.db_data;
2509 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2510 for (i = db->db.db_size >> SPA_BLKPTRSHIFT; i > 0; i--, ibp++) {
2511 if (BP_IS_HOLE(ibp))
2512 continue;
2513 fill += ibp->blk_fill;
2514 }
2515 }
2516 DB_DNODE_EXIT(db);
2517
2518 bp->blk_fill = fill;
2519
2520 mutex_exit(&db->db_mtx);
2521 }
2522
2523 /* ARGSUSED */
2524 static void
2525 dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb)
2526 {
2527 dmu_buf_impl_t *db = vdb;
2528 blkptr_t *bp = zio->io_bp;
2529 blkptr_t *bp_orig = &zio->io_bp_orig;
2530 uint64_t txg = zio->io_txg;
2531 dbuf_dirty_record_t **drp, *dr;
2532
2533 ASSERT0(zio->io_error);
2534 ASSERT(db->db_blkptr == bp);
2535
2536 /*
2537 * For nopwrites and rewrites we ensure that the bp matches our
2538 * original and bypass all the accounting.
2539 */
2540 if (zio->io_flags & (ZIO_FLAG_IO_REWRITE | ZIO_FLAG_NOPWRITE)) {
2541 ASSERT(BP_EQUAL(bp, bp_orig));
2542 } else {
2543 objset_t *os;
2544 dsl_dataset_t *ds;
2545 dmu_tx_t *tx;
2546
2547 DB_GET_OBJSET(&os, db);
2548 ds = os->os_dsl_dataset;
2549 tx = os->os_synctx;
2550
2551 (void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE);
2552 dsl_dataset_block_born(ds, bp, tx);
2553 }
2554
2555 mutex_enter(&db->db_mtx);
2556
2557 DBUF_VERIFY(db);
2558
2559 drp = &db->db_last_dirty;
2560 while ((dr = *drp) != db->db_data_pending)
2561 drp = &dr->dr_next;
2562 ASSERT(!list_link_active(&dr->dr_dirty_node));
2563 ASSERT(dr->dr_txg == txg);
2564 ASSERT(dr->dr_dbuf == db);
2565 ASSERT(dr->dr_next == NULL);
2566 *drp = dr->dr_next;
2567
2568 #ifdef ZFS_DEBUG
2569 if (db->db_blkid == DMU_SPILL_BLKID) {
2570 dnode_t *dn;
2571
2572 DB_DNODE_ENTER(db);
2573 dn = DB_DNODE(db);
2574 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
2575 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
2576 db->db_blkptr == &dn->dn_phys->dn_spill);
2577 DB_DNODE_EXIT(db);
2578 }
2579 #endif
2580
2581 if (db->db_level == 0) {
2582 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
2583 ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
2584 if (db->db_state != DB_NOFILL) {
2585 if (dr->dt.dl.dr_data != db->db_buf)
2586 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data,
2587 db));
2588 else if (!arc_released(db->db_buf))
2589 arc_set_callback(db->db_buf, dbuf_do_evict, db);
2590 }
2591 } else {
2592 dnode_t *dn;
2593
2594 DB_DNODE_ENTER(db);
2595 dn = DB_DNODE(db);
2596 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
2597 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2598 if (!BP_IS_HOLE(db->db_blkptr)) {
2599 int epbs =
2600 dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2601 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==,
2602 db->db.db_size);
2603 ASSERT3U(dn->dn_phys->dn_maxblkid
2604 >> (db->db_level * epbs), >=, db->db_blkid);
2605 arc_set_callback(db->db_buf, dbuf_do_evict, db);
2606 }
2607 DB_DNODE_EXIT(db);
2608 mutex_destroy(&dr->dt.di.dr_mtx);
2609 list_destroy(&dr->dt.di.dr_children);
2610 }
2611 kmem_free(dr, sizeof (dbuf_dirty_record_t));
2612
2613 cv_broadcast(&db->db_changed);
2614 ASSERT(db->db_dirtycnt > 0);
2615 db->db_dirtycnt -= 1;
2616 db->db_data_pending = NULL;
2617 dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg);
2618 }
2619
2620 static void
2621 dbuf_write_nofill_ready(zio_t *zio)
2622 {
2623 dbuf_write_ready(zio, NULL, zio->io_private);
2624 }
2625
2626 static void
2627 dbuf_write_nofill_done(zio_t *zio)
2628 {
2629 dbuf_write_done(zio, NULL, zio->io_private);
2630 }
2631
2632 static void
2633 dbuf_write_override_ready(zio_t *zio)
2634 {
2635 dbuf_dirty_record_t *dr = zio->io_private;
2636 dmu_buf_impl_t *db = dr->dr_dbuf;
2637
2638 dbuf_write_ready(zio, NULL, db);
2639 }
2640
2641 static void
2642 dbuf_write_override_done(zio_t *zio)
2643 {
2644 dbuf_dirty_record_t *dr = zio->io_private;
2645 dmu_buf_impl_t *db = dr->dr_dbuf;
2646 blkptr_t *obp = &dr->dt.dl.dr_overridden_by;
2647
2648 mutex_enter(&db->db_mtx);
2649 if (!BP_EQUAL(zio->io_bp, obp)) {
2650 if (!BP_IS_HOLE(obp))
2651 dsl_free(spa_get_dsl(zio->io_spa), zio->io_txg, obp);
2652 arc_release(dr->dt.dl.dr_data, db);
2653 }
2654 mutex_exit(&db->db_mtx);
2655
2656 dbuf_write_done(zio, NULL, db);
2657 }
2658
2659 /* Issue I/O to commit a dirty buffer to disk. */
2660 static void
2661 dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx)
2662 {
2663 dmu_buf_impl_t *db = dr->dr_dbuf;
2664 dnode_t *dn;
2665 objset_t *os;
2666 dmu_buf_impl_t *parent = db->db_parent;
2667 uint64_t txg = tx->tx_txg;
2668 zbookmark_t zb;
2669 zio_prop_t zp;
2670 zio_t *zio;
2671 int wp_flag = 0;
2672
2673 DB_DNODE_ENTER(db);
2674 dn = DB_DNODE(db);
2675 os = dn->dn_objset;
2676
2677 if (db->db_state != DB_NOFILL) {
2678 if (db->db_level > 0 || dn->dn_type == DMU_OT_DNODE) {
2679 /*
2680 * Private object buffers are released here rather
2681 * than in dbuf_dirty() since they are only modified
2682 * in the syncing context and we don't want the
2683 * overhead of making multiple copies of the data.
2684 */
2685 if (BP_IS_HOLE(db->db_blkptr)) {
2686 arc_buf_thaw(data);
2687 } else {
2688 dbuf_release_bp(db);
2689 }
2690 }
2691 }
2692
2693 if (parent != dn->dn_dbuf) {
2694 /* Our parent is an indirect block. */
2695 /* We have a dirty parent that has been scheduled for write. */
2696 ASSERT(parent && parent->db_data_pending);
2697 /* Our parent's buffer is one level closer to the dnode. */
2698 ASSERT(db->db_level == parent->db_level-1);
2699 /*
2700 * We're about to modify our parent's db_data by modifying
2701 * our block pointer, so the parent must be released.
2702 */
2703 ASSERT(arc_released(parent->db_buf));
2704 zio = parent->db_data_pending->dr_zio;
2705 } else {
2706 /* Our parent is the dnode itself. */
2707 ASSERT((db->db_level == dn->dn_phys->dn_nlevels-1 &&
2708 db->db_blkid != DMU_SPILL_BLKID) ||
2709 (db->db_blkid == DMU_SPILL_BLKID && db->db_level == 0));
2710 if (db->db_blkid != DMU_SPILL_BLKID)
2711 ASSERT3P(db->db_blkptr, ==,
2712 &dn->dn_phys->dn_blkptr[db->db_blkid]);
2713 zio = dn->dn_zio;
2714 }
2715
2716 ASSERT(db->db_level == 0 || data == db->db_buf);
2717 ASSERT3U(db->db_blkptr->blk_birth, <=, txg);
2718 ASSERT(zio);
2719
2720 SET_BOOKMARK(&zb, os->os_dsl_dataset ?
2721 os->os_dsl_dataset->ds_object : DMU_META_OBJSET,
2722 db->db.db_object, db->db_level, db->db_blkid);
2723
2724 if (db->db_blkid == DMU_SPILL_BLKID)
2725 wp_flag = WP_SPILL;
2726 wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0;
2727
2728 dmu_write_policy(os, dn, db->db_level, wp_flag, &zp);
2729 DB_DNODE_EXIT(db);
2730
2731 if (db->db_level == 0 && dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
2732 ASSERT(db->db_state != DB_NOFILL);
2733 dr->dr_zio = zio_write(zio, os->os_spa, txg,
2734 db->db_blkptr, data->b_data, arc_buf_size(data), &zp,
2735 dbuf_write_override_ready, dbuf_write_override_done, dr,
2736 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
2737 mutex_enter(&db->db_mtx);
2738 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
2739 zio_write_override(dr->dr_zio, &dr->dt.dl.dr_overridden_by,
2740 dr->dt.dl.dr_copies, dr->dt.dl.dr_nopwrite);
2741 mutex_exit(&db->db_mtx);
2742 } else if (db->db_state == DB_NOFILL) {
2743 ASSERT(zp.zp_checksum == ZIO_CHECKSUM_OFF);
2744 dr->dr_zio = zio_write(zio, os->os_spa, txg,
2745 db->db_blkptr, NULL, db->db.db_size, &zp,
2746 dbuf_write_nofill_ready, dbuf_write_nofill_done, db,
2747 ZIO_PRIORITY_ASYNC_WRITE,
2748 ZIO_FLAG_MUSTSUCCEED | ZIO_FLAG_NODATA, &zb);
2749 } else {
2750 ASSERT(arc_released(data));
2751 dr->dr_zio = arc_write(zio, os->os_spa, txg,
2752 db->db_blkptr, data, DBUF_IS_L2CACHEABLE(db),
2753 DBUF_IS_L2COMPRESSIBLE(db), &zp, dbuf_write_ready,
2754 dbuf_write_done, db, ZIO_PRIORITY_ASYNC_WRITE,
2755 ZIO_FLAG_MUSTSUCCEED, &zb);
2756 }
2757 }