1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
24 * Copyright (c) 2012, 2014 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 #include <sys/zfeature.h>
44 #include <sys/blkptr.h>
45 #include <sys/range_tree.h>
46
47 /*
48 * Number of times that zfs_free_range() took the slow path while doing
49 * a zfs receive. A nonzero value indicates a potential performance problem.
50 */
51 uint64_t zfs_free_range_recv_miss;
52
53 static void dbuf_destroy(dmu_buf_impl_t *db);
54 static boolean_t dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
55 static void dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx);
56
57 /*
58 * Global data structures and functions for the dbuf cache.
59 */
60 static kmem_cache_t *dbuf_cache;
61
62 /* ARGSUSED */
63 static int
64 dbuf_cons(void *vdb, void *unused, int kmflag)
65 {
66 dmu_buf_impl_t *db = vdb;
67 bzero(db, sizeof (dmu_buf_impl_t));
68
69 mutex_init(&db->db_mtx, NULL, MUTEX_DEFAULT, NULL);
70 cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL);
71 refcount_create(&db->db_holds);
72
73 return (0);
74 }
75
76 /* ARGSUSED */
77 static void
78 dbuf_dest(void *vdb, void *unused)
79 {
80 dmu_buf_impl_t *db = vdb;
81 mutex_destroy(&db->db_mtx);
82 cv_destroy(&db->db_changed);
83 refcount_destroy(&db->db_holds);
84 }
85
86 /*
87 * dbuf hash table routines
88 */
89 static dbuf_hash_table_t dbuf_hash_table;
90
91 static uint64_t dbuf_hash_count;
92
93 static uint64_t
94 dbuf_hash(void *os, uint64_t obj, uint8_t lvl, uint64_t blkid)
95 {
96 uintptr_t osv = (uintptr_t)os;
97 uint64_t crc = -1ULL;
98
99 ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY);
100 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (lvl)) & 0xFF];
101 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (osv >> 6)) & 0xFF];
102 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 0)) & 0xFF];
103 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 8)) & 0xFF];
104 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 0)) & 0xFF];
105 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 8)) & 0xFF];
106
107 crc ^= (osv>>14) ^ (obj>>16) ^ (blkid>>16);
108
109 return (crc);
110 }
111
112 #define DBUF_HASH(os, obj, level, blkid) dbuf_hash(os, obj, level, blkid);
113
114 #define DBUF_EQUAL(dbuf, os, obj, level, blkid) \
115 ((dbuf)->db.db_object == (obj) && \
116 (dbuf)->db_objset == (os) && \
117 (dbuf)->db_level == (level) && \
118 (dbuf)->db_blkid == (blkid))
119
120 dmu_buf_impl_t *
121 dbuf_find(dnode_t *dn, uint8_t level, uint64_t blkid)
122 {
123 dbuf_hash_table_t *h = &dbuf_hash_table;
124 objset_t *os = dn->dn_objset;
125 uint64_t obj = dn->dn_object;
126 uint64_t hv = DBUF_HASH(os, obj, level, blkid);
127 uint64_t idx = hv & h->hash_table_mask;
128 dmu_buf_impl_t *db;
129
130 mutex_enter(DBUF_HASH_MUTEX(h, idx));
131 for (db = h->hash_table[idx]; db != NULL; db = db->db_hash_next) {
132 if (DBUF_EQUAL(db, os, obj, level, blkid)) {
133 mutex_enter(&db->db_mtx);
134 if (db->db_state != DB_EVICTING) {
135 mutex_exit(DBUF_HASH_MUTEX(h, idx));
136 return (db);
137 }
138 mutex_exit(&db->db_mtx);
139 }
140 }
141 mutex_exit(DBUF_HASH_MUTEX(h, idx));
142 return (NULL);
143 }
144
145 /*
146 * Insert an entry into the hash table. If there is already an element
147 * equal to elem in the hash table, then the already existing element
148 * will be returned and the new element will not be inserted.
149 * Otherwise returns NULL.
150 */
151 static dmu_buf_impl_t *
152 dbuf_hash_insert(dmu_buf_impl_t *db)
153 {
154 dbuf_hash_table_t *h = &dbuf_hash_table;
155 objset_t *os = db->db_objset;
156 uint64_t obj = db->db.db_object;
157 int level = db->db_level;
158 uint64_t blkid = db->db_blkid;
159 uint64_t hv = DBUF_HASH(os, obj, level, blkid);
160 uint64_t idx = hv & h->hash_table_mask;
161 dmu_buf_impl_t *dbf;
162
163 mutex_enter(DBUF_HASH_MUTEX(h, idx));
164 for (dbf = h->hash_table[idx]; dbf != NULL; dbf = dbf->db_hash_next) {
165 if (DBUF_EQUAL(dbf, os, obj, level, blkid)) {
166 mutex_enter(&dbf->db_mtx);
167 if (dbf->db_state != DB_EVICTING) {
168 mutex_exit(DBUF_HASH_MUTEX(h, idx));
169 return (dbf);
170 }
171 mutex_exit(&dbf->db_mtx);
172 }
173 }
174
175 mutex_enter(&db->db_mtx);
176 db->db_hash_next = h->hash_table[idx];
177 h->hash_table[idx] = db;
178 mutex_exit(DBUF_HASH_MUTEX(h, idx));
179 atomic_inc_64(&dbuf_hash_count);
180
181 return (NULL);
182 }
183
184 /*
185 * Remove an entry from the hash table. It must be in the EVICTING state.
186 */
187 static void
188 dbuf_hash_remove(dmu_buf_impl_t *db)
189 {
190 dbuf_hash_table_t *h = &dbuf_hash_table;
191 uint64_t hv = DBUF_HASH(db->db_objset, db->db.db_object,
192 db->db_level, db->db_blkid);
193 uint64_t idx = hv & h->hash_table_mask;
194 dmu_buf_impl_t *dbf, **dbp;
195
196 /*
197 * We musn't hold db_mtx to maintain lock ordering:
198 * DBUF_HASH_MUTEX > db_mtx.
199 */
200 ASSERT(refcount_is_zero(&db->db_holds));
201 ASSERT(db->db_state == DB_EVICTING);
202 ASSERT(!MUTEX_HELD(&db->db_mtx));
203
204 mutex_enter(DBUF_HASH_MUTEX(h, idx));
205 dbp = &h->hash_table[idx];
206 while ((dbf = *dbp) != db) {
207 dbp = &dbf->db_hash_next;
208 ASSERT(dbf != NULL);
209 }
210 *dbp = db->db_hash_next;
211 db->db_hash_next = NULL;
212 mutex_exit(DBUF_HASH_MUTEX(h, idx));
213 atomic_dec_64(&dbuf_hash_count);
214 }
215
216 static arc_evict_func_t dbuf_do_evict;
217
218 static void
219 dbuf_evict_user(dmu_buf_impl_t *db)
220 {
221 ASSERT(MUTEX_HELD(&db->db_mtx));
222
223 if (db->db_level != 0 || db->db_evict_func == NULL)
224 return;
225
226 if (db->db_user_data_ptr_ptr)
227 *db->db_user_data_ptr_ptr = db->db.db_data;
228 db->db_evict_func(&db->db, db->db_user_ptr);
229 db->db_user_ptr = NULL;
230 db->db_user_data_ptr_ptr = NULL;
231 db->db_evict_func = NULL;
232 }
233
234 boolean_t
235 dbuf_is_metadata(dmu_buf_impl_t *db)
236 {
237 if (db->db_level > 0) {
238 return (B_TRUE);
239 } else {
240 boolean_t is_metadata;
241
242 DB_DNODE_ENTER(db);
243 is_metadata = DMU_OT_IS_METADATA(DB_DNODE(db)->dn_type);
244 DB_DNODE_EXIT(db);
245
246 return (is_metadata);
247 }
248 }
249
250 void
251 dbuf_evict(dmu_buf_impl_t *db)
252 {
253 ASSERT(MUTEX_HELD(&db->db_mtx));
254 ASSERT(db->db_buf == NULL);
255 ASSERT(db->db_data_pending == NULL);
256
257 dbuf_clear(db);
258 dbuf_destroy(db);
259 }
260
261 void
262 dbuf_init(void)
263 {
264 uint64_t hsize = 1ULL << 16;
265 dbuf_hash_table_t *h = &dbuf_hash_table;
266 int i;
267
268 /*
269 * The hash table is big enough to fill all of physical memory
270 * with an average 4K block size. The table will take up
271 * totalmem*sizeof(void*)/4K (i.e. 2MB/GB with 8-byte pointers).
272 */
273 while (hsize * 4096 < physmem * PAGESIZE)
274 hsize <<= 1;
275
276 retry:
277 h->hash_table_mask = hsize - 1;
278 h->hash_table = kmem_zalloc(hsize * sizeof (void *), KM_NOSLEEP);
279 if (h->hash_table == NULL) {
280 /* XXX - we should really return an error instead of assert */
281 ASSERT(hsize > (1ULL << 10));
282 hsize >>= 1;
283 goto retry;
284 }
285
286 dbuf_cache = kmem_cache_create("dmu_buf_impl_t",
287 sizeof (dmu_buf_impl_t),
288 0, dbuf_cons, dbuf_dest, NULL, NULL, NULL, 0);
289
290 for (i = 0; i < DBUF_MUTEXES; i++)
291 mutex_init(&h->hash_mutexes[i], NULL, MUTEX_DEFAULT, NULL);
292 }
293
294 void
295 dbuf_fini(void)
296 {
297 dbuf_hash_table_t *h = &dbuf_hash_table;
298 int i;
299
300 for (i = 0; i < DBUF_MUTEXES; i++)
301 mutex_destroy(&h->hash_mutexes[i]);
302 kmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *));
303 kmem_cache_destroy(dbuf_cache);
304 }
305
306 /*
307 * Other stuff.
308 */
309
310 #ifdef ZFS_DEBUG
311 static void
312 dbuf_verify(dmu_buf_impl_t *db)
313 {
314 dnode_t *dn;
315 dbuf_dirty_record_t *dr;
316
317 ASSERT(MUTEX_HELD(&db->db_mtx));
318
319 if (!(zfs_flags & ZFS_DEBUG_DBUF_VERIFY))
320 return;
321
322 ASSERT(db->db_objset != NULL);
323 DB_DNODE_ENTER(db);
324 dn = DB_DNODE(db);
325 if (dn == NULL) {
326 ASSERT(db->db_parent == NULL);
327 ASSERT(db->db_blkptr == NULL);
328 } else {
329 ASSERT3U(db->db.db_object, ==, dn->dn_object);
330 ASSERT3P(db->db_objset, ==, dn->dn_objset);
331 ASSERT3U(db->db_level, <, dn->dn_nlevels);
332 ASSERT(db->db_blkid == DMU_BONUS_BLKID ||
333 db->db_blkid == DMU_SPILL_BLKID ||
334 !avl_is_empty(&dn->dn_dbufs));
335 }
336 if (db->db_blkid == DMU_BONUS_BLKID) {
337 ASSERT(dn != NULL);
338 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
339 ASSERT3U(db->db.db_offset, ==, DMU_BONUS_BLKID);
340 } else if (db->db_blkid == DMU_SPILL_BLKID) {
341 ASSERT(dn != NULL);
342 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
343 ASSERT0(db->db.db_offset);
344 } else {
345 ASSERT3U(db->db.db_offset, ==, db->db_blkid * db->db.db_size);
346 }
347
348 for (dr = db->db_data_pending; dr != NULL; dr = dr->dr_next)
349 ASSERT(dr->dr_dbuf == db);
350
351 for (dr = db->db_last_dirty; dr != NULL; dr = dr->dr_next)
352 ASSERT(dr->dr_dbuf == db);
353
354 /*
355 * We can't assert that db_size matches dn_datablksz because it
356 * can be momentarily different when another thread is doing
357 * dnode_set_blksz().
358 */
359 if (db->db_level == 0 && db->db.db_object == DMU_META_DNODE_OBJECT) {
360 dr = db->db_data_pending;
361 /*
362 * It should only be modified in syncing context, so
363 * make sure we only have one copy of the data.
364 */
365 ASSERT(dr == NULL || dr->dt.dl.dr_data == db->db_buf);
366 }
367
368 /* verify db->db_blkptr */
369 if (db->db_blkptr) {
370 if (db->db_parent == dn->dn_dbuf) {
371 /* db is pointed to by the dnode */
372 /* ASSERT3U(db->db_blkid, <, dn->dn_nblkptr); */
373 if (DMU_OBJECT_IS_SPECIAL(db->db.db_object))
374 ASSERT(db->db_parent == NULL);
375 else
376 ASSERT(db->db_parent != NULL);
377 if (db->db_blkid != DMU_SPILL_BLKID)
378 ASSERT3P(db->db_blkptr, ==,
379 &dn->dn_phys->dn_blkptr[db->db_blkid]);
380 } else {
381 /* db is pointed to by an indirect block */
382 int epb = db->db_parent->db.db_size >> SPA_BLKPTRSHIFT;
383 ASSERT3U(db->db_parent->db_level, ==, db->db_level+1);
384 ASSERT3U(db->db_parent->db.db_object, ==,
385 db->db.db_object);
386 /*
387 * dnode_grow_indblksz() can make this fail if we don't
388 * have the struct_rwlock. XXX indblksz no longer
389 * grows. safe to do this now?
390 */
391 if (RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
392 ASSERT3P(db->db_blkptr, ==,
393 ((blkptr_t *)db->db_parent->db.db_data +
394 db->db_blkid % epb));
395 }
396 }
397 }
398 if ((db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr)) &&
399 (db->db_buf == NULL || db->db_buf->b_data) &&
400 db->db.db_data && db->db_blkid != DMU_BONUS_BLKID &&
401 db->db_state != DB_FILL && !dn->dn_free_txg) {
402 /*
403 * If the blkptr isn't set but they have nonzero data,
404 * it had better be dirty, otherwise we'll lose that
405 * data when we evict this buffer.
406 */
407 if (db->db_dirtycnt == 0) {
408 uint64_t *buf = db->db.db_data;
409 int i;
410
411 for (i = 0; i < db->db.db_size >> 3; i++) {
412 ASSERT(buf[i] == 0);
413 }
414 }
415 }
416 DB_DNODE_EXIT(db);
417 }
418 #endif
419
420 static void
421 dbuf_update_data(dmu_buf_impl_t *db)
422 {
423 ASSERT(MUTEX_HELD(&db->db_mtx));
424 if (db->db_level == 0 && db->db_user_data_ptr_ptr) {
425 ASSERT(!refcount_is_zero(&db->db_holds));
426 *db->db_user_data_ptr_ptr = db->db.db_data;
427 }
428 }
429
430 static void
431 dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf)
432 {
433 ASSERT(MUTEX_HELD(&db->db_mtx));
434 db->db_buf = buf;
435 if (buf != NULL) {
436 ASSERT(buf->b_data != NULL);
437 db->db.db_data = buf->b_data;
438 if (!arc_released(buf))
439 arc_set_callback(buf, dbuf_do_evict, db);
440 dbuf_update_data(db);
441 } else {
442 dbuf_evict_user(db);
443 db->db.db_data = NULL;
444 if (db->db_state != DB_NOFILL)
445 db->db_state = DB_UNCACHED;
446 }
447 }
448
449 /*
450 * Loan out an arc_buf for read. Return the loaned arc_buf.
451 */
452 arc_buf_t *
453 dbuf_loan_arcbuf(dmu_buf_impl_t *db)
454 {
455 arc_buf_t *abuf;
456
457 mutex_enter(&db->db_mtx);
458 if (arc_released(db->db_buf) || refcount_count(&db->db_holds) > 1) {
459 int blksz = db->db.db_size;
460 spa_t *spa = db->db_objset->os_spa;
461
462 mutex_exit(&db->db_mtx);
463 abuf = arc_loan_buf(spa, blksz);
464 bcopy(db->db.db_data, abuf->b_data, blksz);
465 } else {
466 abuf = db->db_buf;
467 arc_loan_inuse_buf(abuf, db);
468 dbuf_set_data(db, NULL);
469 mutex_exit(&db->db_mtx);
470 }
471 return (abuf);
472 }
473
474 uint64_t
475 dbuf_whichblock(dnode_t *dn, uint64_t offset)
476 {
477 if (dn->dn_datablkshift) {
478 return (offset >> dn->dn_datablkshift);
479 } else {
480 ASSERT3U(offset, <, dn->dn_datablksz);
481 return (0);
482 }
483 }
484
485 static void
486 dbuf_read_done(zio_t *zio, arc_buf_t *buf, void *vdb)
487 {
488 dmu_buf_impl_t *db = vdb;
489
490 mutex_enter(&db->db_mtx);
491 ASSERT3U(db->db_state, ==, DB_READ);
492 /*
493 * All reads are synchronous, so we must have a hold on the dbuf
494 */
495 ASSERT(refcount_count(&db->db_holds) > 0);
496 ASSERT(db->db_buf == NULL);
497 ASSERT(db->db.db_data == NULL);
498 if (db->db_level == 0 && db->db_freed_in_flight) {
499 /* we were freed in flight; disregard any error */
500 arc_release(buf, db);
501 bzero(buf->b_data, db->db.db_size);
502 arc_buf_freeze(buf);
503 db->db_freed_in_flight = FALSE;
504 dbuf_set_data(db, buf);
505 db->db_state = DB_CACHED;
506 } else if (zio == NULL || zio->io_error == 0) {
507 dbuf_set_data(db, buf);
508 db->db_state = DB_CACHED;
509 } else {
510 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
511 ASSERT3P(db->db_buf, ==, NULL);
512 VERIFY(arc_buf_remove_ref(buf, db));
513 db->db_state = DB_UNCACHED;
514 }
515 cv_broadcast(&db->db_changed);
516 dbuf_rele_and_unlock(db, NULL);
517 }
518
519 static void
520 dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t *flags)
521 {
522 dnode_t *dn;
523 zbookmark_phys_t zb;
524 uint32_t aflags = ARC_NOWAIT;
525
526 DB_DNODE_ENTER(db);
527 dn = DB_DNODE(db);
528 ASSERT(!refcount_is_zero(&db->db_holds));
529 /* We need the struct_rwlock to prevent db_blkptr from changing. */
530 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
531 ASSERT(MUTEX_HELD(&db->db_mtx));
532 ASSERT(db->db_state == DB_UNCACHED);
533 ASSERT(db->db_buf == NULL);
534
535 if (db->db_blkid == DMU_BONUS_BLKID) {
536 int bonuslen = MIN(dn->dn_bonuslen, dn->dn_phys->dn_bonuslen);
537
538 ASSERT3U(bonuslen, <=, db->db.db_size);
539 db->db.db_data = zio_buf_alloc(DN_MAX_BONUSLEN);
540 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
541 if (bonuslen < DN_MAX_BONUSLEN)
542 bzero(db->db.db_data, DN_MAX_BONUSLEN);
543 if (bonuslen)
544 bcopy(DN_BONUS(dn->dn_phys), db->db.db_data, bonuslen);
545 DB_DNODE_EXIT(db);
546 dbuf_update_data(db);
547 db->db_state = DB_CACHED;
548 mutex_exit(&db->db_mtx);
549 return;
550 }
551
552 /*
553 * Recheck BP_IS_HOLE() after dnode_block_freed() in case dnode_sync()
554 * processes the delete record and clears the bp while we are waiting
555 * for the dn_mtx (resulting in a "no" from block_freed).
556 */
557 if (db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr) ||
558 (db->db_level == 0 && (dnode_block_freed(dn, db->db_blkid) ||
559 BP_IS_HOLE(db->db_blkptr)))) {
560 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
561
562 DB_DNODE_EXIT(db);
563 dbuf_set_data(db, arc_buf_alloc(db->db_objset->os_spa,
564 db->db.db_size, db, type));
565 bzero(db->db.db_data, db->db.db_size);
566 db->db_state = DB_CACHED;
567 *flags |= DB_RF_CACHED;
568 mutex_exit(&db->db_mtx);
569 return;
570 }
571
572 DB_DNODE_EXIT(db);
573
574 db->db_state = DB_READ;
575 mutex_exit(&db->db_mtx);
576
577 if (DBUF_IS_L2CACHEABLE(db))
578 aflags |= ARC_L2CACHE;
579 if (DBUF_IS_L2COMPRESSIBLE(db))
580 aflags |= ARC_L2COMPRESS;
581
582 SET_BOOKMARK(&zb, db->db_objset->os_dsl_dataset ?
583 db->db_objset->os_dsl_dataset->ds_object : DMU_META_OBJSET,
584 db->db.db_object, db->db_level, db->db_blkid);
585
586 dbuf_add_ref(db, NULL);
587
588 (void) arc_read(zio, db->db_objset->os_spa, db->db_blkptr,
589 dbuf_read_done, db, ZIO_PRIORITY_SYNC_READ,
590 (*flags & DB_RF_CANFAIL) ? ZIO_FLAG_CANFAIL : ZIO_FLAG_MUSTSUCCEED,
591 &aflags, &zb);
592 if (aflags & ARC_CACHED)
593 *flags |= DB_RF_CACHED;
594 }
595
596 int
597 dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
598 {
599 int err = 0;
600 boolean_t havepzio = (zio != NULL);
601 boolean_t prefetch;
602 dnode_t *dn;
603
604 /*
605 * We don't have to hold the mutex to check db_state because it
606 * can't be freed while we have a hold on the buffer.
607 */
608 ASSERT(!refcount_is_zero(&db->db_holds));
609
610 if (db->db_state == DB_NOFILL)
611 return (SET_ERROR(EIO));
612
613 DB_DNODE_ENTER(db);
614 dn = DB_DNODE(db);
615 if ((flags & DB_RF_HAVESTRUCT) == 0)
616 rw_enter(&dn->dn_struct_rwlock, RW_READER);
617
618 prefetch = db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
619 (flags & DB_RF_NOPREFETCH) == 0 && dn != NULL &&
620 DBUF_IS_CACHEABLE(db);
621
622 mutex_enter(&db->db_mtx);
623 if (db->db_state == DB_CACHED) {
624 mutex_exit(&db->db_mtx);
625 if (prefetch)
626 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset,
627 db->db.db_size, TRUE);
628 if ((flags & DB_RF_HAVESTRUCT) == 0)
629 rw_exit(&dn->dn_struct_rwlock);
630 DB_DNODE_EXIT(db);
631 } else if (db->db_state == DB_UNCACHED) {
632 spa_t *spa = dn->dn_objset->os_spa;
633
634 if (zio == NULL)
635 zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL);
636 dbuf_read_impl(db, zio, &flags);
637
638 /* dbuf_read_impl has dropped db_mtx for us */
639
640 if (prefetch)
641 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset,
642 db->db.db_size, flags & DB_RF_CACHED);
643
644 if ((flags & DB_RF_HAVESTRUCT) == 0)
645 rw_exit(&dn->dn_struct_rwlock);
646 DB_DNODE_EXIT(db);
647
648 if (!havepzio)
649 err = zio_wait(zio);
650 } else {
651 /*
652 * Another reader came in while the dbuf was in flight
653 * between UNCACHED and CACHED. Either a writer will finish
654 * writing the buffer (sending the dbuf to CACHED) or the
655 * first reader's request will reach the read_done callback
656 * and send the dbuf to CACHED. Otherwise, a failure
657 * occurred and the dbuf went to UNCACHED.
658 */
659 mutex_exit(&db->db_mtx);
660 if (prefetch)
661 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset,
662 db->db.db_size, TRUE);
663 if ((flags & DB_RF_HAVESTRUCT) == 0)
664 rw_exit(&dn->dn_struct_rwlock);
665 DB_DNODE_EXIT(db);
666
667 /* Skip the wait per the caller's request. */
668 mutex_enter(&db->db_mtx);
669 if ((flags & DB_RF_NEVERWAIT) == 0) {
670 while (db->db_state == DB_READ ||
671 db->db_state == DB_FILL) {
672 ASSERT(db->db_state == DB_READ ||
673 (flags & DB_RF_HAVESTRUCT) == 0);
674 DTRACE_PROBE2(blocked__read, dmu_buf_impl_t *,
675 db, zio_t *, zio);
676 cv_wait(&db->db_changed, &db->db_mtx);
677 }
678 if (db->db_state == DB_UNCACHED)
679 err = SET_ERROR(EIO);
680 }
681 mutex_exit(&db->db_mtx);
682 }
683
684 ASSERT(err || havepzio || db->db_state == DB_CACHED);
685 return (err);
686 }
687
688 static void
689 dbuf_noread(dmu_buf_impl_t *db)
690 {
691 ASSERT(!refcount_is_zero(&db->db_holds));
692 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
693 mutex_enter(&db->db_mtx);
694 while (db->db_state == DB_READ || db->db_state == DB_FILL)
695 cv_wait(&db->db_changed, &db->db_mtx);
696 if (db->db_state == DB_UNCACHED) {
697 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
698 spa_t *spa = db->db_objset->os_spa;
699
700 ASSERT(db->db_buf == NULL);
701 ASSERT(db->db.db_data == NULL);
702 dbuf_set_data(db, arc_buf_alloc(spa, db->db.db_size, db, type));
703 db->db_state = DB_FILL;
704 } else if (db->db_state == DB_NOFILL) {
705 dbuf_set_data(db, NULL);
706 } else {
707 ASSERT3U(db->db_state, ==, DB_CACHED);
708 }
709 mutex_exit(&db->db_mtx);
710 }
711
712 /*
713 * This is our just-in-time copy function. It makes a copy of
714 * buffers, that have been modified in a previous transaction
715 * group, before we modify them in the current active group.
716 *
717 * This function is used in two places: when we are dirtying a
718 * buffer for the first time in a txg, and when we are freeing
719 * a range in a dnode that includes this buffer.
720 *
721 * Note that when we are called from dbuf_free_range() we do
722 * not put a hold on the buffer, we just traverse the active
723 * dbuf list for the dnode.
724 */
725 static void
726 dbuf_fix_old_data(dmu_buf_impl_t *db, uint64_t txg)
727 {
728 dbuf_dirty_record_t *dr = db->db_last_dirty;
729
730 ASSERT(MUTEX_HELD(&db->db_mtx));
731 ASSERT(db->db.db_data != NULL);
732 ASSERT(db->db_level == 0);
733 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT);
734
735 if (dr == NULL ||
736 (dr->dt.dl.dr_data !=
737 ((db->db_blkid == DMU_BONUS_BLKID) ? db->db.db_data : db->db_buf)))
738 return;
739
740 /*
741 * If the last dirty record for this dbuf has not yet synced
742 * and its referencing the dbuf data, either:
743 * reset the reference to point to a new copy,
744 * or (if there a no active holders)
745 * just null out the current db_data pointer.
746 */
747 ASSERT(dr->dr_txg >= txg - 2);
748 if (db->db_blkid == DMU_BONUS_BLKID) {
749 /* Note that the data bufs here are zio_bufs */
750 dr->dt.dl.dr_data = zio_buf_alloc(DN_MAX_BONUSLEN);
751 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
752 bcopy(db->db.db_data, dr->dt.dl.dr_data, DN_MAX_BONUSLEN);
753 } else if (refcount_count(&db->db_holds) > db->db_dirtycnt) {
754 int size = db->db.db_size;
755 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
756 spa_t *spa = db->db_objset->os_spa;
757
758 dr->dt.dl.dr_data = arc_buf_alloc(spa, size, db, type);
759 bcopy(db->db.db_data, dr->dt.dl.dr_data->b_data, size);
760 } else {
761 dbuf_set_data(db, NULL);
762 }
763 }
764
765 void
766 dbuf_unoverride(dbuf_dirty_record_t *dr)
767 {
768 dmu_buf_impl_t *db = dr->dr_dbuf;
769 blkptr_t *bp = &dr->dt.dl.dr_overridden_by;
770 uint64_t txg = dr->dr_txg;
771
772 ASSERT(MUTEX_HELD(&db->db_mtx));
773 ASSERT(dr->dt.dl.dr_override_state != DR_IN_DMU_SYNC);
774 ASSERT(db->db_level == 0);
775
776 if (db->db_blkid == DMU_BONUS_BLKID ||
777 dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN)
778 return;
779
780 ASSERT(db->db_data_pending != dr);
781
782 /* free this block */
783 if (!BP_IS_HOLE(bp) && !dr->dt.dl.dr_nopwrite)
784 zio_free(db->db_objset->os_spa, txg, bp);
785
786 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
787 dr->dt.dl.dr_nopwrite = B_FALSE;
788
789 /*
790 * Release the already-written buffer, so we leave it in
791 * a consistent dirty state. Note that all callers are
792 * modifying the buffer, so they will immediately do
793 * another (redundant) arc_release(). Therefore, leave
794 * the buf thawed to save the effort of freezing &
795 * immediately re-thawing it.
796 */
797 arc_release(dr->dt.dl.dr_data, db);
798 }
799
800 /*
801 * Evict (if its unreferenced) or clear (if its referenced) any level-0
802 * data blocks in the free range, so that any future readers will find
803 * empty blocks.
804 *
805 * This is a no-op if the dataset is in the middle of an incremental
806 * receive; see comment below for details.
807 */
808 void
809 dbuf_free_range(dnode_t *dn, uint64_t start_blkid, uint64_t end_blkid,
810 dmu_tx_t *tx)
811 {
812 dmu_buf_impl_t *db, *db_next, db_search;
813 uint64_t txg = tx->tx_txg;
814 avl_index_t where;
815
816 if (end_blkid > dn->dn_maxblkid && (end_blkid != DMU_SPILL_BLKID))
817 end_blkid = dn->dn_maxblkid;
818 dprintf_dnode(dn, "start=%llu end=%llu\n", start_blkid, end_blkid);
819
820 db_search.db_level = 0;
821 db_search.db_blkid = start_blkid;
822 db_search.db_state = DB_SEARCH;
823
824 mutex_enter(&dn->dn_dbufs_mtx);
825 if (start_blkid >= dn->dn_unlisted_l0_blkid) {
826 /* There can't be any dbufs in this range; no need to search. */
827 #ifdef DEBUG
828 db = avl_find(&dn->dn_dbufs, &db_search, &where);
829 ASSERT3P(db, ==, NULL);
830 db = avl_nearest(&dn->dn_dbufs, where, AVL_AFTER);
831 ASSERT(db == NULL || db->db_level > 0);
832 #endif
833 mutex_exit(&dn->dn_dbufs_mtx);
834 return;
835 } else if (dmu_objset_is_receiving(dn->dn_objset)) {
836 /*
837 * If we are receiving, we expect there to be no dbufs in
838 * the range to be freed, because receive modifies each
839 * block at most once, and in offset order. If this is
840 * not the case, it can lead to performance problems,
841 * so note that we unexpectedly took the slow path.
842 */
843 atomic_inc_64(&zfs_free_range_recv_miss);
844 }
845
846 db = avl_find(&dn->dn_dbufs, &db_search, &where);
847 ASSERT3P(db, ==, NULL);
848 db = avl_nearest(&dn->dn_dbufs, where, AVL_AFTER);
849
850 for (; db != NULL; db = db_next) {
851 db_next = AVL_NEXT(&dn->dn_dbufs, db);
852 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
853
854 if (db->db_level != 0 || db->db_blkid > end_blkid) {
855 break;
856 }
857 ASSERT3U(db->db_blkid, >=, start_blkid);
858
859 /* found a level 0 buffer in the range */
860 mutex_enter(&db->db_mtx);
861 if (dbuf_undirty(db, tx)) {
862 /* mutex has been dropped and dbuf destroyed */
863 continue;
864 }
865
866 if (db->db_state == DB_UNCACHED ||
867 db->db_state == DB_NOFILL ||
868 db->db_state == DB_EVICTING) {
869 ASSERT(db->db.db_data == NULL);
870 mutex_exit(&db->db_mtx);
871 continue;
872 }
873 if (db->db_state == DB_READ || db->db_state == DB_FILL) {
874 /* will be handled in dbuf_read_done or dbuf_rele */
875 db->db_freed_in_flight = TRUE;
876 mutex_exit(&db->db_mtx);
877 continue;
878 }
879 if (refcount_count(&db->db_holds) == 0) {
880 ASSERT(db->db_buf);
881 dbuf_clear(db);
882 continue;
883 }
884 /* The dbuf is referenced */
885
886 if (db->db_last_dirty != NULL) {
887 dbuf_dirty_record_t *dr = db->db_last_dirty;
888
889 if (dr->dr_txg == txg) {
890 /*
891 * This buffer is "in-use", re-adjust the file
892 * size to reflect that this buffer may
893 * contain new data when we sync.
894 */
895 if (db->db_blkid != DMU_SPILL_BLKID &&
896 db->db_blkid > dn->dn_maxblkid)
897 dn->dn_maxblkid = db->db_blkid;
898 dbuf_unoverride(dr);
899 } else {
900 /*
901 * This dbuf is not dirty in the open context.
902 * Either uncache it (if its not referenced in
903 * the open context) or reset its contents to
904 * empty.
905 */
906 dbuf_fix_old_data(db, txg);
907 }
908 }
909 /* clear the contents if its cached */
910 if (db->db_state == DB_CACHED) {
911 ASSERT(db->db.db_data != NULL);
912 arc_release(db->db_buf, db);
913 bzero(db->db.db_data, db->db.db_size);
914 arc_buf_freeze(db->db_buf);
915 }
916
917 mutex_exit(&db->db_mtx);
918 }
919 mutex_exit(&dn->dn_dbufs_mtx);
920 }
921
922 static int
923 dbuf_block_freeable(dmu_buf_impl_t *db)
924 {
925 dsl_dataset_t *ds = db->db_objset->os_dsl_dataset;
926 uint64_t birth_txg = 0;
927
928 /*
929 * We don't need any locking to protect db_blkptr:
930 * If it's syncing, then db_last_dirty will be set
931 * so we'll ignore db_blkptr.
932 *
933 * This logic ensures that only block births for
934 * filled blocks are considered.
935 */
936 ASSERT(MUTEX_HELD(&db->db_mtx));
937 if (db->db_last_dirty && (db->db_blkptr == NULL ||
938 !BP_IS_HOLE(db->db_blkptr))) {
939 birth_txg = db->db_last_dirty->dr_txg;
940 } else if (db->db_blkptr != NULL && !BP_IS_HOLE(db->db_blkptr)) {
941 birth_txg = db->db_blkptr->blk_birth;
942 }
943
944 /*
945 * If this block don't exist or is in a snapshot, it can't be freed.
946 * Don't pass the bp to dsl_dataset_block_freeable() since we
947 * are holding the db_mtx lock and might deadlock if we are
948 * prefetching a dedup-ed block.
949 */
950 if (birth_txg != 0)
951 return (ds == NULL ||
952 dsl_dataset_block_freeable(ds, NULL, birth_txg));
953 else
954 return (B_FALSE);
955 }
956
957 void
958 dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx)
959 {
960 arc_buf_t *buf, *obuf;
961 int osize = db->db.db_size;
962 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
963 dnode_t *dn;
964
965 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
966
967 DB_DNODE_ENTER(db);
968 dn = DB_DNODE(db);
969
970 /* XXX does *this* func really need the lock? */
971 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
972
973 /*
974 * This call to dmu_buf_will_dirty() with the dn_struct_rwlock held
975 * is OK, because there can be no other references to the db
976 * when we are changing its size, so no concurrent DB_FILL can
977 * be happening.
978 */
979 /*
980 * XXX we should be doing a dbuf_read, checking the return
981 * value and returning that up to our callers
982 */
983 dmu_buf_will_dirty(&db->db, tx);
984
985 /* create the data buffer for the new block */
986 buf = arc_buf_alloc(dn->dn_objset->os_spa, size, db, type);
987
988 /* copy old block data to the new block */
989 obuf = db->db_buf;
990 bcopy(obuf->b_data, buf->b_data, MIN(osize, size));
991 /* zero the remainder */
992 if (size > osize)
993 bzero((uint8_t *)buf->b_data + osize, size - osize);
994
995 mutex_enter(&db->db_mtx);
996 dbuf_set_data(db, buf);
997 VERIFY(arc_buf_remove_ref(obuf, db));
998 db->db.db_size = size;
999
1000 if (db->db_level == 0) {
1001 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
1002 db->db_last_dirty->dt.dl.dr_data = buf;
1003 }
1004 mutex_exit(&db->db_mtx);
1005
1006 dnode_willuse_space(dn, size-osize, tx);
1007 DB_DNODE_EXIT(db);
1008 }
1009
1010 void
1011 dbuf_release_bp(dmu_buf_impl_t *db)
1012 {
1013 objset_t *os = db->db_objset;
1014
1015 ASSERT(dsl_pool_sync_context(dmu_objset_pool(os)));
1016 ASSERT(arc_released(os->os_phys_buf) ||
1017 list_link_active(&os->os_dsl_dataset->ds_synced_link));
1018 ASSERT(db->db_parent == NULL || arc_released(db->db_parent->db_buf));
1019
1020 (void) arc_release(db->db_buf, db);
1021 }
1022
1023 dbuf_dirty_record_t *
1024 dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1025 {
1026 dnode_t *dn;
1027 objset_t *os;
1028 dbuf_dirty_record_t **drp, *dr;
1029 int drop_struct_lock = FALSE;
1030 boolean_t do_free_accounting = B_FALSE;
1031 int txgoff = tx->tx_txg & TXG_MASK;
1032
1033 ASSERT(tx->tx_txg != 0);
1034 ASSERT(!refcount_is_zero(&db->db_holds));
1035 DMU_TX_DIRTY_BUF(tx, db);
1036
1037 DB_DNODE_ENTER(db);
1038 dn = DB_DNODE(db);
1039 /*
1040 * Shouldn't dirty a regular buffer in syncing context. Private
1041 * objects may be dirtied in syncing context, but only if they
1042 * were already pre-dirtied in open context.
1043 */
1044 ASSERT(!dmu_tx_is_syncing(tx) ||
1045 BP_IS_HOLE(dn->dn_objset->os_rootbp) ||
1046 DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1047 dn->dn_objset->os_dsl_dataset == NULL);
1048 /*
1049 * We make this assert for private objects as well, but after we
1050 * check if we're already dirty. They are allowed to re-dirty
1051 * in syncing context.
1052 */
1053 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1054 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1055 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1056
1057 mutex_enter(&db->db_mtx);
1058 /*
1059 * XXX make this true for indirects too? The problem is that
1060 * transactions created with dmu_tx_create_assigned() from
1061 * syncing context don't bother holding ahead.
1062 */
1063 ASSERT(db->db_level != 0 ||
1064 db->db_state == DB_CACHED || db->db_state == DB_FILL ||
1065 db->db_state == DB_NOFILL);
1066
1067 mutex_enter(&dn->dn_mtx);
1068 /*
1069 * Don't set dirtyctx to SYNC if we're just modifying this as we
1070 * initialize the objset.
1071 */
1072 if (dn->dn_dirtyctx == DN_UNDIRTIED &&
1073 !BP_IS_HOLE(dn->dn_objset->os_rootbp)) {
1074 dn->dn_dirtyctx =
1075 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN);
1076 ASSERT(dn->dn_dirtyctx_firstset == NULL);
1077 dn->dn_dirtyctx_firstset = kmem_alloc(1, KM_SLEEP);
1078 }
1079 mutex_exit(&dn->dn_mtx);
1080
1081 if (db->db_blkid == DMU_SPILL_BLKID)
1082 dn->dn_have_spill = B_TRUE;
1083
1084 /*
1085 * If this buffer is already dirty, we're done.
1086 */
1087 drp = &db->db_last_dirty;
1088 ASSERT(*drp == NULL || (*drp)->dr_txg <= tx->tx_txg ||
1089 db->db.db_object == DMU_META_DNODE_OBJECT);
1090 while ((dr = *drp) != NULL && dr->dr_txg > tx->tx_txg)
1091 drp = &dr->dr_next;
1092 if (dr && dr->dr_txg == tx->tx_txg) {
1093 DB_DNODE_EXIT(db);
1094
1095 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID) {
1096 /*
1097 * If this buffer has already been written out,
1098 * we now need to reset its state.
1099 */
1100 dbuf_unoverride(dr);
1101 if (db->db.db_object != DMU_META_DNODE_OBJECT &&
1102 db->db_state != DB_NOFILL)
1103 arc_buf_thaw(db->db_buf);
1104 }
1105 mutex_exit(&db->db_mtx);
1106 return (dr);
1107 }
1108
1109 /*
1110 * Only valid if not already dirty.
1111 */
1112 ASSERT(dn->dn_object == 0 ||
1113 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1114 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1115
1116 ASSERT3U(dn->dn_nlevels, >, db->db_level);
1117 ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) ||
1118 dn->dn_phys->dn_nlevels > db->db_level ||
1119 dn->dn_next_nlevels[txgoff] > db->db_level ||
1120 dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level ||
1121 dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level);
1122
1123 /*
1124 * We should only be dirtying in syncing context if it's the
1125 * mos or we're initializing the os or it's a special object.
1126 * However, we are allowed to dirty in syncing context provided
1127 * we already dirtied it in open context. Hence we must make
1128 * this assertion only if we're not already dirty.
1129 */
1130 os = dn->dn_objset;
1131 ASSERT(!dmu_tx_is_syncing(tx) || DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1132 os->os_dsl_dataset == NULL || BP_IS_HOLE(os->os_rootbp));
1133 ASSERT(db->db.db_size != 0);
1134
1135 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1136
1137 if (db->db_blkid != DMU_BONUS_BLKID) {
1138 /*
1139 * Update the accounting.
1140 * Note: we delay "free accounting" until after we drop
1141 * the db_mtx. This keeps us from grabbing other locks
1142 * (and possibly deadlocking) in bp_get_dsize() while
1143 * also holding the db_mtx.
1144 */
1145 dnode_willuse_space(dn, db->db.db_size, tx);
1146 do_free_accounting = dbuf_block_freeable(db);
1147 }
1148
1149 /*
1150 * If this buffer is dirty in an old transaction group we need
1151 * to make a copy of it so that the changes we make in this
1152 * transaction group won't leak out when we sync the older txg.
1153 */
1154 dr = kmem_zalloc(sizeof (dbuf_dirty_record_t), KM_SLEEP);
1155 if (db->db_level == 0) {
1156 void *data_old = db->db_buf;
1157
1158 if (db->db_state != DB_NOFILL) {
1159 if (db->db_blkid == DMU_BONUS_BLKID) {
1160 dbuf_fix_old_data(db, tx->tx_txg);
1161 data_old = db->db.db_data;
1162 } else if (db->db.db_object != DMU_META_DNODE_OBJECT) {
1163 /*
1164 * Release the data buffer from the cache so
1165 * that we can modify it without impacting
1166 * possible other users of this cached data
1167 * block. Note that indirect blocks and
1168 * private objects are not released until the
1169 * syncing state (since they are only modified
1170 * then).
1171 */
1172 arc_release(db->db_buf, db);
1173 dbuf_fix_old_data(db, tx->tx_txg);
1174 data_old = db->db_buf;
1175 }
1176 ASSERT(data_old != NULL);
1177 }
1178 dr->dt.dl.dr_data = data_old;
1179 } else {
1180 mutex_init(&dr->dt.di.dr_mtx, NULL, MUTEX_DEFAULT, NULL);
1181 list_create(&dr->dt.di.dr_children,
1182 sizeof (dbuf_dirty_record_t),
1183 offsetof(dbuf_dirty_record_t, dr_dirty_node));
1184 }
1185 if (db->db_blkid != DMU_BONUS_BLKID && os->os_dsl_dataset != NULL)
1186 dr->dr_accounted = db->db.db_size;
1187 dr->dr_dbuf = db;
1188 dr->dr_txg = tx->tx_txg;
1189 dr->dr_next = *drp;
1190 *drp = dr;
1191
1192 /*
1193 * We could have been freed_in_flight between the dbuf_noread
1194 * and dbuf_dirty. We win, as though the dbuf_noread() had
1195 * happened after the free.
1196 */
1197 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
1198 db->db_blkid != DMU_SPILL_BLKID) {
1199 mutex_enter(&dn->dn_mtx);
1200 if (dn->dn_free_ranges[txgoff] != NULL) {
1201 range_tree_clear(dn->dn_free_ranges[txgoff],
1202 db->db_blkid, 1);
1203 }
1204 mutex_exit(&dn->dn_mtx);
1205 db->db_freed_in_flight = FALSE;
1206 }
1207
1208 /*
1209 * This buffer is now part of this txg
1210 */
1211 dbuf_add_ref(db, (void *)(uintptr_t)tx->tx_txg);
1212 db->db_dirtycnt += 1;
1213 ASSERT3U(db->db_dirtycnt, <=, 3);
1214
1215 mutex_exit(&db->db_mtx);
1216
1217 if (db->db_blkid == DMU_BONUS_BLKID ||
1218 db->db_blkid == DMU_SPILL_BLKID) {
1219 mutex_enter(&dn->dn_mtx);
1220 ASSERT(!list_link_active(&dr->dr_dirty_node));
1221 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1222 mutex_exit(&dn->dn_mtx);
1223 dnode_setdirty(dn, tx);
1224 DB_DNODE_EXIT(db);
1225 return (dr);
1226 } else if (do_free_accounting) {
1227 blkptr_t *bp = db->db_blkptr;
1228 int64_t willfree = (bp && !BP_IS_HOLE(bp)) ?
1229 bp_get_dsize(os->os_spa, bp) : db->db.db_size;
1230 /*
1231 * This is only a guess -- if the dbuf is dirty
1232 * in a previous txg, we don't know how much
1233 * space it will use on disk yet. We should
1234 * really have the struct_rwlock to access
1235 * db_blkptr, but since this is just a guess,
1236 * it's OK if we get an odd answer.
1237 */
1238 ddt_prefetch(os->os_spa, bp);
1239 dnode_willuse_space(dn, -willfree, tx);
1240 }
1241
1242 if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
1243 rw_enter(&dn->dn_struct_rwlock, RW_READER);
1244 drop_struct_lock = TRUE;
1245 }
1246
1247 if (db->db_level == 0) {
1248 dnode_new_blkid(dn, db->db_blkid, tx, drop_struct_lock);
1249 ASSERT(dn->dn_maxblkid >= db->db_blkid);
1250 }
1251
1252 if (db->db_level+1 < dn->dn_nlevels) {
1253 dmu_buf_impl_t *parent = db->db_parent;
1254 dbuf_dirty_record_t *di;
1255 int parent_held = FALSE;
1256
1257 if (db->db_parent == NULL || db->db_parent == dn->dn_dbuf) {
1258 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1259
1260 parent = dbuf_hold_level(dn, db->db_level+1,
1261 db->db_blkid >> epbs, FTAG);
1262 ASSERT(parent != NULL);
1263 parent_held = TRUE;
1264 }
1265 if (drop_struct_lock)
1266 rw_exit(&dn->dn_struct_rwlock);
1267 ASSERT3U(db->db_level+1, ==, parent->db_level);
1268 di = dbuf_dirty(parent, tx);
1269 if (parent_held)
1270 dbuf_rele(parent, FTAG);
1271
1272 mutex_enter(&db->db_mtx);
1273 /*
1274 * Since we've dropped the mutex, it's possible that
1275 * dbuf_undirty() might have changed this out from under us.
1276 */
1277 if (db->db_last_dirty == dr ||
1278 dn->dn_object == DMU_META_DNODE_OBJECT) {
1279 mutex_enter(&di->dt.di.dr_mtx);
1280 ASSERT3U(di->dr_txg, ==, tx->tx_txg);
1281 ASSERT(!list_link_active(&dr->dr_dirty_node));
1282 list_insert_tail(&di->dt.di.dr_children, dr);
1283 mutex_exit(&di->dt.di.dr_mtx);
1284 dr->dr_parent = di;
1285 }
1286 mutex_exit(&db->db_mtx);
1287 } else {
1288 ASSERT(db->db_level+1 == dn->dn_nlevels);
1289 ASSERT(db->db_blkid < dn->dn_nblkptr);
1290 ASSERT(db->db_parent == NULL || db->db_parent == dn->dn_dbuf);
1291 mutex_enter(&dn->dn_mtx);
1292 ASSERT(!list_link_active(&dr->dr_dirty_node));
1293 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1294 mutex_exit(&dn->dn_mtx);
1295 if (drop_struct_lock)
1296 rw_exit(&dn->dn_struct_rwlock);
1297 }
1298
1299 dnode_setdirty(dn, tx);
1300 DB_DNODE_EXIT(db);
1301 return (dr);
1302 }
1303
1304 /*
1305 * Undirty a buffer in the transaction group referenced by the given
1306 * transaction. Return whether this evicted the dbuf.
1307 */
1308 static boolean_t
1309 dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1310 {
1311 dnode_t *dn;
1312 uint64_t txg = tx->tx_txg;
1313 dbuf_dirty_record_t *dr, **drp;
1314
1315 ASSERT(txg != 0);
1316 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1317 ASSERT0(db->db_level);
1318 ASSERT(MUTEX_HELD(&db->db_mtx));
1319
1320 /*
1321 * If this buffer is not dirty, we're done.
1322 */
1323 for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next)
1324 if (dr->dr_txg <= txg)
1325 break;
1326 if (dr == NULL || dr->dr_txg < txg)
1327 return (B_FALSE);
1328 ASSERT(dr->dr_txg == txg);
1329 ASSERT(dr->dr_dbuf == db);
1330
1331 DB_DNODE_ENTER(db);
1332 dn = DB_DNODE(db);
1333
1334 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1335
1336 ASSERT(db->db.db_size != 0);
1337
1338 /*
1339 * Any space we accounted for in dp_dirty_* will be cleaned up by
1340 * dsl_pool_sync(). This is relatively rare so the discrepancy
1341 * is not a big deal.
1342 */
1343
1344 *drp = dr->dr_next;
1345
1346 /*
1347 * Note that there are three places in dbuf_dirty()
1348 * where this dirty record may be put on a list.
1349 * Make sure to do a list_remove corresponding to
1350 * every one of those list_insert calls.
1351 */
1352 if (dr->dr_parent) {
1353 mutex_enter(&dr->dr_parent->dt.di.dr_mtx);
1354 list_remove(&dr->dr_parent->dt.di.dr_children, dr);
1355 mutex_exit(&dr->dr_parent->dt.di.dr_mtx);
1356 } else if (db->db_blkid == DMU_SPILL_BLKID ||
1357 db->db_level+1 == dn->dn_nlevels) {
1358 ASSERT(db->db_blkptr == NULL || db->db_parent == dn->dn_dbuf);
1359 mutex_enter(&dn->dn_mtx);
1360 list_remove(&dn->dn_dirty_records[txg & TXG_MASK], dr);
1361 mutex_exit(&dn->dn_mtx);
1362 }
1363 DB_DNODE_EXIT(db);
1364
1365 if (db->db_state != DB_NOFILL) {
1366 dbuf_unoverride(dr);
1367
1368 ASSERT(db->db_buf != NULL);
1369 ASSERT(dr->dt.dl.dr_data != NULL);
1370 if (dr->dt.dl.dr_data != db->db_buf)
1371 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data, db));
1372 }
1373
1374 if (db->db_level != 0) {
1375 mutex_destroy(&dr->dt.di.dr_mtx);
1376 list_destroy(&dr->dt.di.dr_children);
1377 }
1378
1379 kmem_free(dr, sizeof (dbuf_dirty_record_t));
1380
1381 ASSERT(db->db_dirtycnt > 0);
1382 db->db_dirtycnt -= 1;
1383
1384 if (refcount_remove(&db->db_holds, (void *)(uintptr_t)txg) == 0) {
1385 arc_buf_t *buf = db->db_buf;
1386
1387 ASSERT(db->db_state == DB_NOFILL || arc_released(buf));
1388 dbuf_set_data(db, NULL);
1389 VERIFY(arc_buf_remove_ref(buf, db));
1390 dbuf_evict(db);
1391 return (B_TRUE);
1392 }
1393
1394 return (B_FALSE);
1395 }
1396
1397 void
1398 dmu_buf_will_dirty(dmu_buf_t *db_fake, dmu_tx_t *tx)
1399 {
1400 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1401 int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH;
1402
1403 ASSERT(tx->tx_txg != 0);
1404 ASSERT(!refcount_is_zero(&db->db_holds));
1405
1406 DB_DNODE_ENTER(db);
1407 if (RW_WRITE_HELD(&DB_DNODE(db)->dn_struct_rwlock))
1408 rf |= DB_RF_HAVESTRUCT;
1409 DB_DNODE_EXIT(db);
1410 (void) dbuf_read(db, NULL, rf);
1411 (void) dbuf_dirty(db, tx);
1412 }
1413
1414 void
1415 dmu_buf_will_not_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1416 {
1417 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1418
1419 db->db_state = DB_NOFILL;
1420
1421 dmu_buf_will_fill(db_fake, tx);
1422 }
1423
1424 void
1425 dmu_buf_will_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1426 {
1427 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1428
1429 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1430 ASSERT(tx->tx_txg != 0);
1431 ASSERT(db->db_level == 0);
1432 ASSERT(!refcount_is_zero(&db->db_holds));
1433
1434 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT ||
1435 dmu_tx_private_ok(tx));
1436
1437 dbuf_noread(db);
1438 (void) dbuf_dirty(db, tx);
1439 }
1440
1441 #pragma weak dmu_buf_fill_done = dbuf_fill_done
1442 /* ARGSUSED */
1443 void
1444 dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx)
1445 {
1446 mutex_enter(&db->db_mtx);
1447 DBUF_VERIFY(db);
1448
1449 if (db->db_state == DB_FILL) {
1450 if (db->db_level == 0 && db->db_freed_in_flight) {
1451 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1452 /* we were freed while filling */
1453 /* XXX dbuf_undirty? */
1454 bzero(db->db.db_data, db->db.db_size);
1455 db->db_freed_in_flight = FALSE;
1456 }
1457 db->db_state = DB_CACHED;
1458 cv_broadcast(&db->db_changed);
1459 }
1460 mutex_exit(&db->db_mtx);
1461 }
1462
1463 void
1464 dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
1465 bp_embedded_type_t etype, enum zio_compress comp,
1466 int uncompressed_size, int compressed_size, int byteorder,
1467 dmu_tx_t *tx)
1468 {
1469 dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf;
1470 struct dirty_leaf *dl;
1471 dmu_object_type_t type;
1472
1473 DB_DNODE_ENTER(db);
1474 type = DB_DNODE(db)->dn_type;
1475 DB_DNODE_EXIT(db);
1476
1477 ASSERT0(db->db_level);
1478 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1479
1480 dmu_buf_will_not_fill(dbuf, tx);
1481
1482 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
1483 dl = &db->db_last_dirty->dt.dl;
1484 encode_embedded_bp_compressed(&dl->dr_overridden_by,
1485 data, comp, uncompressed_size, compressed_size);
1486 BPE_SET_ETYPE(&dl->dr_overridden_by, etype);
1487 BP_SET_TYPE(&dl->dr_overridden_by, type);
1488 BP_SET_LEVEL(&dl->dr_overridden_by, 0);
1489 BP_SET_BYTEORDER(&dl->dr_overridden_by, byteorder);
1490
1491 dl->dr_override_state = DR_OVERRIDDEN;
1492 dl->dr_overridden_by.blk_birth = db->db_last_dirty->dr_txg;
1493 }
1494
1495 /*
1496 * Directly assign a provided arc buf to a given dbuf if it's not referenced
1497 * by anybody except our caller. Otherwise copy arcbuf's contents to dbuf.
1498 */
1499 void
1500 dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx)
1501 {
1502 ASSERT(!refcount_is_zero(&db->db_holds));
1503 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1504 ASSERT(db->db_level == 0);
1505 ASSERT(DBUF_GET_BUFC_TYPE(db) == ARC_BUFC_DATA);
1506 ASSERT(buf != NULL);
1507 ASSERT(arc_buf_size(buf) == db->db.db_size);
1508 ASSERT(tx->tx_txg != 0);
1509
1510 arc_return_buf(buf, db);
1511 ASSERT(arc_released(buf));
1512
1513 mutex_enter(&db->db_mtx);
1514
1515 while (db->db_state == DB_READ || db->db_state == DB_FILL)
1516 cv_wait(&db->db_changed, &db->db_mtx);
1517
1518 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED);
1519
1520 if (db->db_state == DB_CACHED &&
1521 refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) {
1522 mutex_exit(&db->db_mtx);
1523 (void) dbuf_dirty(db, tx);
1524 bcopy(buf->b_data, db->db.db_data, db->db.db_size);
1525 VERIFY(arc_buf_remove_ref(buf, db));
1526 xuio_stat_wbuf_copied();
1527 return;
1528 }
1529
1530 xuio_stat_wbuf_nocopy();
1531 if (db->db_state == DB_CACHED) {
1532 dbuf_dirty_record_t *dr = db->db_last_dirty;
1533
1534 ASSERT(db->db_buf != NULL);
1535 if (dr != NULL && dr->dr_txg == tx->tx_txg) {
1536 ASSERT(dr->dt.dl.dr_data == db->db_buf);
1537 if (!arc_released(db->db_buf)) {
1538 ASSERT(dr->dt.dl.dr_override_state ==
1539 DR_OVERRIDDEN);
1540 arc_release(db->db_buf, db);
1541 }
1542 dr->dt.dl.dr_data = buf;
1543 VERIFY(arc_buf_remove_ref(db->db_buf, db));
1544 } else if (dr == NULL || dr->dt.dl.dr_data != db->db_buf) {
1545 arc_release(db->db_buf, db);
1546 VERIFY(arc_buf_remove_ref(db->db_buf, db));
1547 }
1548 db->db_buf = NULL;
1549 }
1550 ASSERT(db->db_buf == NULL);
1551 dbuf_set_data(db, buf);
1552 db->db_state = DB_FILL;
1553 mutex_exit(&db->db_mtx);
1554 (void) dbuf_dirty(db, tx);
1555 dmu_buf_fill_done(&db->db, tx);
1556 }
1557
1558 /*
1559 * "Clear" the contents of this dbuf. This will mark the dbuf
1560 * EVICTING and clear *most* of its references. Unfortunately,
1561 * when we are not holding the dn_dbufs_mtx, we can't clear the
1562 * entry in the dn_dbufs list. We have to wait until dbuf_destroy()
1563 * in this case. For callers from the DMU we will usually see:
1564 * dbuf_clear()->arc_clear_callback()->dbuf_do_evict()->dbuf_destroy()
1565 * For the arc callback, we will usually see:
1566 * dbuf_do_evict()->dbuf_clear();dbuf_destroy()
1567 * Sometimes, though, we will get a mix of these two:
1568 * DMU: dbuf_clear()->arc_clear_callback()
1569 * ARC: dbuf_do_evict()->dbuf_destroy()
1570 *
1571 * This routine will dissociate the dbuf from the arc, by calling
1572 * arc_clear_callback(), but will not evict the data from the ARC.
1573 */
1574 void
1575 dbuf_clear(dmu_buf_impl_t *db)
1576 {
1577 dnode_t *dn;
1578 dmu_buf_impl_t *parent = db->db_parent;
1579 dmu_buf_impl_t *dndb;
1580 boolean_t dbuf_gone = B_FALSE;
1581
1582 ASSERT(MUTEX_HELD(&db->db_mtx));
1583 ASSERT(refcount_is_zero(&db->db_holds));
1584
1585 dbuf_evict_user(db);
1586
1587 if (db->db_state == DB_CACHED) {
1588 ASSERT(db->db.db_data != NULL);
1589 if (db->db_blkid == DMU_BONUS_BLKID) {
1590 zio_buf_free(db->db.db_data, DN_MAX_BONUSLEN);
1591 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
1592 }
1593 db->db.db_data = NULL;
1594 db->db_state = DB_UNCACHED;
1595 }
1596
1597 ASSERT(db->db_state == DB_UNCACHED || db->db_state == DB_NOFILL);
1598 ASSERT(db->db_data_pending == NULL);
1599
1600 db->db_state = DB_EVICTING;
1601 db->db_blkptr = NULL;
1602
1603 DB_DNODE_ENTER(db);
1604 dn = DB_DNODE(db);
1605 dndb = dn->dn_dbuf;
1606 if (db->db_blkid != DMU_BONUS_BLKID && MUTEX_HELD(&dn->dn_dbufs_mtx)) {
1607 avl_remove(&dn->dn_dbufs, db);
1608 atomic_dec_32(&dn->dn_dbufs_count);
1609 membar_producer();
1610 DB_DNODE_EXIT(db);
1611 /*
1612 * Decrementing the dbuf count means that the hold corresponding
1613 * to the removed dbuf is no longer discounted in dnode_move(),
1614 * so the dnode cannot be moved until after we release the hold.
1615 * The membar_producer() ensures visibility of the decremented
1616 * value in dnode_move(), since DB_DNODE_EXIT doesn't actually
1617 * release any lock.
1618 */
1619 dnode_rele(dn, db);
1620 db->db_dnode_handle = NULL;
1621 } else {
1622 DB_DNODE_EXIT(db);
1623 }
1624
1625 if (db->db_buf)
1626 dbuf_gone = arc_clear_callback(db->db_buf);
1627
1628 if (!dbuf_gone)
1629 mutex_exit(&db->db_mtx);
1630
1631 /*
1632 * If this dbuf is referenced from an indirect dbuf,
1633 * decrement the ref count on the indirect dbuf.
1634 */
1635 if (parent && parent != dndb)
1636 dbuf_rele(parent, db);
1637 }
1638
1639 static int
1640 dbuf_findbp(dnode_t *dn, int level, uint64_t blkid, int fail_sparse,
1641 dmu_buf_impl_t **parentp, blkptr_t **bpp)
1642 {
1643 int nlevels, epbs;
1644
1645 *parentp = NULL;
1646 *bpp = NULL;
1647
1648 ASSERT(blkid != DMU_BONUS_BLKID);
1649
1650 if (blkid == DMU_SPILL_BLKID) {
1651 mutex_enter(&dn->dn_mtx);
1652 if (dn->dn_have_spill &&
1653 (dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR))
1654 *bpp = &dn->dn_phys->dn_spill;
1655 else
1656 *bpp = NULL;
1657 dbuf_add_ref(dn->dn_dbuf, NULL);
1658 *parentp = dn->dn_dbuf;
1659 mutex_exit(&dn->dn_mtx);
1660 return (0);
1661 }
1662
1663 if (dn->dn_phys->dn_nlevels == 0)
1664 nlevels = 1;
1665 else
1666 nlevels = dn->dn_phys->dn_nlevels;
1667
1668 epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1669
1670 ASSERT3U(level * epbs, <, 64);
1671 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1672 if (level >= nlevels ||
1673 (blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))) {
1674 /* the buffer has no parent yet */
1675 return (SET_ERROR(ENOENT));
1676 } else if (level < nlevels-1) {
1677 /* this block is referenced from an indirect block */
1678 int err = dbuf_hold_impl(dn, level+1,
1679 blkid >> epbs, fail_sparse, NULL, parentp);
1680 if (err)
1681 return (err);
1682 err = dbuf_read(*parentp, NULL,
1683 (DB_RF_HAVESTRUCT | DB_RF_NOPREFETCH | DB_RF_CANFAIL));
1684 if (err) {
1685 dbuf_rele(*parentp, NULL);
1686 *parentp = NULL;
1687 return (err);
1688 }
1689 *bpp = ((blkptr_t *)(*parentp)->db.db_data) +
1690 (blkid & ((1ULL << epbs) - 1));
1691 return (0);
1692 } else {
1693 /* the block is referenced from the dnode */
1694 ASSERT3U(level, ==, nlevels-1);
1695 ASSERT(dn->dn_phys->dn_nblkptr == 0 ||
1696 blkid < dn->dn_phys->dn_nblkptr);
1697 if (dn->dn_dbuf) {
1698 dbuf_add_ref(dn->dn_dbuf, NULL);
1699 *parentp = dn->dn_dbuf;
1700 }
1701 *bpp = &dn->dn_phys->dn_blkptr[blkid];
1702 return (0);
1703 }
1704 }
1705
1706 static dmu_buf_impl_t *
1707 dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid,
1708 dmu_buf_impl_t *parent, blkptr_t *blkptr)
1709 {
1710 objset_t *os = dn->dn_objset;
1711 dmu_buf_impl_t *db, *odb;
1712
1713 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1714 ASSERT(dn->dn_type != DMU_OT_NONE);
1715
1716 db = kmem_cache_alloc(dbuf_cache, KM_SLEEP);
1717
1718 db->db_objset = os;
1719 db->db.db_object = dn->dn_object;
1720 db->db_level = level;
1721 db->db_blkid = blkid;
1722 db->db_last_dirty = NULL;
1723 db->db_dirtycnt = 0;
1724 db->db_dnode_handle = dn->dn_handle;
1725 db->db_parent = parent;
1726 db->db_blkptr = blkptr;
1727
1728 db->db_user_ptr = NULL;
1729 db->db_user_data_ptr_ptr = NULL;
1730 db->db_evict_func = NULL;
1731 db->db_immediate_evict = 0;
1732 db->db_freed_in_flight = 0;
1733
1734 if (blkid == DMU_BONUS_BLKID) {
1735 ASSERT3P(parent, ==, dn->dn_dbuf);
1736 db->db.db_size = DN_MAX_BONUSLEN -
1737 (dn->dn_nblkptr-1) * sizeof (blkptr_t);
1738 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
1739 db->db.db_offset = DMU_BONUS_BLKID;
1740 db->db_state = DB_UNCACHED;
1741 /* the bonus dbuf is not placed in the hash table */
1742 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1743 return (db);
1744 } else if (blkid == DMU_SPILL_BLKID) {
1745 db->db.db_size = (blkptr != NULL) ?
1746 BP_GET_LSIZE(blkptr) : SPA_MINBLOCKSIZE;
1747 db->db.db_offset = 0;
1748 } else {
1749 int blocksize =
1750 db->db_level ? 1 << dn->dn_indblkshift : dn->dn_datablksz;
1751 db->db.db_size = blocksize;
1752 db->db.db_offset = db->db_blkid * blocksize;
1753 }
1754
1755 /*
1756 * Hold the dn_dbufs_mtx while we get the new dbuf
1757 * in the hash table *and* added to the dbufs list.
1758 * This prevents a possible deadlock with someone
1759 * trying to look up this dbuf before its added to the
1760 * dn_dbufs list.
1761 */
1762 mutex_enter(&dn->dn_dbufs_mtx);
1763 db->db_state = DB_EVICTING;
1764 if ((odb = dbuf_hash_insert(db)) != NULL) {
1765 /* someone else inserted it first */
1766 kmem_cache_free(dbuf_cache, db);
1767 mutex_exit(&dn->dn_dbufs_mtx);
1768 return (odb);
1769 }
1770 avl_add(&dn->dn_dbufs, db);
1771 if (db->db_level == 0 && db->db_blkid >=
1772 dn->dn_unlisted_l0_blkid)
1773 dn->dn_unlisted_l0_blkid = db->db_blkid + 1;
1774 db->db_state = DB_UNCACHED;
1775 mutex_exit(&dn->dn_dbufs_mtx);
1776 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1777
1778 if (parent && parent != dn->dn_dbuf)
1779 dbuf_add_ref(parent, db);
1780
1781 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1782 refcount_count(&dn->dn_holds) > 0);
1783 (void) refcount_add(&dn->dn_holds, db);
1784 atomic_inc_32(&dn->dn_dbufs_count);
1785
1786 dprintf_dbuf(db, "db=%p\n", db);
1787
1788 return (db);
1789 }
1790
1791 static int
1792 dbuf_do_evict(void *private)
1793 {
1794 dmu_buf_impl_t *db = private;
1795
1796 if (!MUTEX_HELD(&db->db_mtx))
1797 mutex_enter(&db->db_mtx);
1798
1799 ASSERT(refcount_is_zero(&db->db_holds));
1800
1801 if (db->db_state != DB_EVICTING) {
1802 ASSERT(db->db_state == DB_CACHED);
1803 DBUF_VERIFY(db);
1804 db->db_buf = NULL;
1805 dbuf_evict(db);
1806 } else {
1807 mutex_exit(&db->db_mtx);
1808 dbuf_destroy(db);
1809 }
1810 return (0);
1811 }
1812
1813 static void
1814 dbuf_destroy(dmu_buf_impl_t *db)
1815 {
1816 ASSERT(refcount_is_zero(&db->db_holds));
1817
1818 if (db->db_blkid != DMU_BONUS_BLKID) {
1819 /*
1820 * If this dbuf is still on the dn_dbufs list,
1821 * remove it from that list.
1822 */
1823 if (db->db_dnode_handle != NULL) {
1824 dnode_t *dn;
1825
1826 DB_DNODE_ENTER(db);
1827 dn = DB_DNODE(db);
1828 mutex_enter(&dn->dn_dbufs_mtx);
1829 avl_remove(&dn->dn_dbufs, db);
1830 atomic_dec_32(&dn->dn_dbufs_count);
1831 mutex_exit(&dn->dn_dbufs_mtx);
1832 DB_DNODE_EXIT(db);
1833 /*
1834 * Decrementing the dbuf count means that the hold
1835 * corresponding to the removed dbuf is no longer
1836 * discounted in dnode_move(), so the dnode cannot be
1837 * moved until after we release the hold.
1838 */
1839 dnode_rele(dn, db);
1840 db->db_dnode_handle = NULL;
1841 }
1842 dbuf_hash_remove(db);
1843 }
1844 db->db_parent = NULL;
1845 db->db_buf = NULL;
1846
1847 ASSERT(db->db.db_data == NULL);
1848 ASSERT(db->db_hash_next == NULL);
1849 ASSERT(db->db_blkptr == NULL);
1850 ASSERT(db->db_data_pending == NULL);
1851
1852 kmem_cache_free(dbuf_cache, db);
1853 arc_space_return(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
1854 }
1855
1856 void
1857 dbuf_prefetch(dnode_t *dn, uint64_t blkid, zio_priority_t prio)
1858 {
1859 dmu_buf_impl_t *db = NULL;
1860 blkptr_t *bp = NULL;
1861
1862 ASSERT(blkid != DMU_BONUS_BLKID);
1863 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1864
1865 if (dnode_block_freed(dn, blkid))
1866 return;
1867
1868 /* dbuf_find() returns with db_mtx held */
1869 if (db = dbuf_find(dn, 0, blkid)) {
1870 /*
1871 * This dbuf is already in the cache. We assume that
1872 * it is already CACHED, or else about to be either
1873 * read or filled.
1874 */
1875 mutex_exit(&db->db_mtx);
1876 return;
1877 }
1878
1879 if (dbuf_findbp(dn, 0, blkid, TRUE, &db, &bp) == 0) {
1880 if (bp && !BP_IS_HOLE(bp) && !BP_IS_EMBEDDED(bp)) {
1881 dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset;
1882 uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH;
1883 zbookmark_phys_t zb;
1884
1885 SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
1886 dn->dn_object, 0, blkid);
1887
1888 (void) arc_read(NULL, dn->dn_objset->os_spa,
1889 bp, NULL, NULL, prio,
1890 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
1891 &aflags, &zb);
1892 }
1893 if (db)
1894 dbuf_rele(db, NULL);
1895 }
1896 }
1897
1898 /*
1899 * Returns with db_holds incremented, and db_mtx not held.
1900 * Note: dn_struct_rwlock must be held.
1901 */
1902 int
1903 dbuf_hold_impl(dnode_t *dn, uint8_t level, uint64_t blkid, int fail_sparse,
1904 void *tag, dmu_buf_impl_t **dbp)
1905 {
1906 dmu_buf_impl_t *db, *parent = NULL;
1907
1908 ASSERT(blkid != DMU_BONUS_BLKID);
1909 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1910 ASSERT3U(dn->dn_nlevels, >, level);
1911
1912 *dbp = NULL;
1913 top:
1914 /* dbuf_find() returns with db_mtx held */
1915 db = dbuf_find(dn, level, blkid);
1916
1917 if (db == NULL) {
1918 blkptr_t *bp = NULL;
1919 int err;
1920
1921 ASSERT3P(parent, ==, NULL);
1922 err = dbuf_findbp(dn, level, blkid, fail_sparse, &parent, &bp);
1923 if (fail_sparse) {
1924 if (err == 0 && bp && BP_IS_HOLE(bp))
1925 err = SET_ERROR(ENOENT);
1926 if (err) {
1927 if (parent)
1928 dbuf_rele(parent, NULL);
1929 return (err);
1930 }
1931 }
1932 if (err && err != ENOENT)
1933 return (err);
1934 db = dbuf_create(dn, level, blkid, parent, bp);
1935 }
1936
1937 if (db->db_buf && refcount_is_zero(&db->db_holds)) {
1938 arc_buf_add_ref(db->db_buf, db);
1939 if (db->db_buf->b_data == NULL) {
1940 dbuf_clear(db);
1941 if (parent) {
1942 dbuf_rele(parent, NULL);
1943 parent = NULL;
1944 }
1945 goto top;
1946 }
1947 ASSERT3P(db->db.db_data, ==, db->db_buf->b_data);
1948 }
1949
1950 ASSERT(db->db_buf == NULL || arc_referenced(db->db_buf));
1951
1952 /*
1953 * If this buffer is currently syncing out, and we are are
1954 * still referencing it from db_data, we need to make a copy
1955 * of it in case we decide we want to dirty it again in this txg.
1956 */
1957 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
1958 dn->dn_object != DMU_META_DNODE_OBJECT &&
1959 db->db_state == DB_CACHED && db->db_data_pending) {
1960 dbuf_dirty_record_t *dr = db->db_data_pending;
1961
1962 if (dr->dt.dl.dr_data == db->db_buf) {
1963 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
1964
1965 dbuf_set_data(db,
1966 arc_buf_alloc(dn->dn_objset->os_spa,
1967 db->db.db_size, db, type));
1968 bcopy(dr->dt.dl.dr_data->b_data, db->db.db_data,
1969 db->db.db_size);
1970 }
1971 }
1972
1973 (void) refcount_add(&db->db_holds, tag);
1974 dbuf_update_data(db);
1975 DBUF_VERIFY(db);
1976 mutex_exit(&db->db_mtx);
1977
1978 /* NOTE: we can't rele the parent until after we drop the db_mtx */
1979 if (parent)
1980 dbuf_rele(parent, NULL);
1981
1982 ASSERT3P(DB_DNODE(db), ==, dn);
1983 ASSERT3U(db->db_blkid, ==, blkid);
1984 ASSERT3U(db->db_level, ==, level);
1985 *dbp = db;
1986
1987 return (0);
1988 }
1989
1990 dmu_buf_impl_t *
1991 dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag)
1992 {
1993 dmu_buf_impl_t *db;
1994 int err = dbuf_hold_impl(dn, 0, blkid, FALSE, tag, &db);
1995 return (err ? NULL : db);
1996 }
1997
1998 dmu_buf_impl_t *
1999 dbuf_hold_level(dnode_t *dn, int level, uint64_t blkid, void *tag)
2000 {
2001 dmu_buf_impl_t *db;
2002 int err = dbuf_hold_impl(dn, level, blkid, FALSE, tag, &db);
2003 return (err ? NULL : db);
2004 }
2005
2006 void
2007 dbuf_create_bonus(dnode_t *dn)
2008 {
2009 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
2010
2011 ASSERT(dn->dn_bonus == NULL);
2012 dn->dn_bonus = dbuf_create(dn, 0, DMU_BONUS_BLKID, dn->dn_dbuf, NULL);
2013 }
2014
2015 int
2016 dbuf_spill_set_blksz(dmu_buf_t *db_fake, uint64_t blksz, dmu_tx_t *tx)
2017 {
2018 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2019 dnode_t *dn;
2020
2021 if (db->db_blkid != DMU_SPILL_BLKID)
2022 return (SET_ERROR(ENOTSUP));
2023 if (blksz == 0)
2024 blksz = SPA_MINBLOCKSIZE;
2025 if (blksz > SPA_MAXBLOCKSIZE)
2026 blksz = SPA_MAXBLOCKSIZE;
2027 else
2028 blksz = P2ROUNDUP(blksz, SPA_MINBLOCKSIZE);
2029
2030 DB_DNODE_ENTER(db);
2031 dn = DB_DNODE(db);
2032 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
2033 dbuf_new_size(db, blksz, tx);
2034 rw_exit(&dn->dn_struct_rwlock);
2035 DB_DNODE_EXIT(db);
2036
2037 return (0);
2038 }
2039
2040 void
2041 dbuf_rm_spill(dnode_t *dn, dmu_tx_t *tx)
2042 {
2043 dbuf_free_range(dn, DMU_SPILL_BLKID, DMU_SPILL_BLKID, tx);
2044 }
2045
2046 #pragma weak dmu_buf_add_ref = dbuf_add_ref
2047 void
2048 dbuf_add_ref(dmu_buf_impl_t *db, void *tag)
2049 {
2050 int64_t holds = refcount_add(&db->db_holds, tag);
2051 ASSERT(holds > 1);
2052 }
2053
2054 /*
2055 * If you call dbuf_rele() you had better not be referencing the dnode handle
2056 * unless you have some other direct or indirect hold on the dnode. (An indirect
2057 * hold is a hold on one of the dnode's dbufs, including the bonus buffer.)
2058 * Without that, the dbuf_rele() could lead to a dnode_rele() followed by the
2059 * dnode's parent dbuf evicting its dnode handles.
2060 */
2061 void
2062 dbuf_rele(dmu_buf_impl_t *db, void *tag)
2063 {
2064 mutex_enter(&db->db_mtx);
2065 dbuf_rele_and_unlock(db, tag);
2066 }
2067
2068 void
2069 dmu_buf_rele(dmu_buf_t *db, void *tag)
2070 {
2071 dbuf_rele((dmu_buf_impl_t *)db, tag);
2072 }
2073
2074 /*
2075 * dbuf_rele() for an already-locked dbuf. This is necessary to allow
2076 * db_dirtycnt and db_holds to be updated atomically.
2077 */
2078 void
2079 dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag)
2080 {
2081 int64_t holds;
2082
2083 ASSERT(MUTEX_HELD(&db->db_mtx));
2084 DBUF_VERIFY(db);
2085
2086 /*
2087 * Remove the reference to the dbuf before removing its hold on the
2088 * dnode so we can guarantee in dnode_move() that a referenced bonus
2089 * buffer has a corresponding dnode hold.
2090 */
2091 holds = refcount_remove(&db->db_holds, tag);
2092 ASSERT(holds >= 0);
2093
2094 /*
2095 * We can't freeze indirects if there is a possibility that they
2096 * may be modified in the current syncing context.
2097 */
2098 if (db->db_buf && holds == (db->db_level == 0 ? db->db_dirtycnt : 0))
2099 arc_buf_freeze(db->db_buf);
2100
2101 if (holds == db->db_dirtycnt &&
2102 db->db_level == 0 && db->db_immediate_evict)
2103 dbuf_evict_user(db);
2104
2105 if (holds == 0) {
2106 if (db->db_blkid == DMU_BONUS_BLKID) {
2107 mutex_exit(&db->db_mtx);
2108
2109 /*
2110 * If the dnode moves here, we cannot cross this barrier
2111 * until the move completes.
2112 */
2113 DB_DNODE_ENTER(db);
2114 atomic_dec_32(&DB_DNODE(db)->dn_dbufs_count);
2115 DB_DNODE_EXIT(db);
2116 /*
2117 * The bonus buffer's dnode hold is no longer discounted
2118 * in dnode_move(). The dnode cannot move until after
2119 * the dnode_rele().
2120 */
2121 dnode_rele(DB_DNODE(db), db);
2122 } else if (db->db_buf == NULL) {
2123 /*
2124 * This is a special case: we never associated this
2125 * dbuf with any data allocated from the ARC.
2126 */
2127 ASSERT(db->db_state == DB_UNCACHED ||
2128 db->db_state == DB_NOFILL);
2129 dbuf_evict(db);
2130 } else if (arc_released(db->db_buf)) {
2131 arc_buf_t *buf = db->db_buf;
2132 /*
2133 * This dbuf has anonymous data associated with it.
2134 */
2135 dbuf_set_data(db, NULL);
2136 VERIFY(arc_buf_remove_ref(buf, db));
2137 dbuf_evict(db);
2138 } else {
2139 VERIFY(!arc_buf_remove_ref(db->db_buf, db));
2140
2141 /*
2142 * A dbuf will be eligible for eviction if either the
2143 * 'primarycache' property is set or a duplicate
2144 * copy of this buffer is already cached in the arc.
2145 *
2146 * In the case of the 'primarycache' a buffer
2147 * is considered for eviction if it matches the
2148 * criteria set in the property.
2149 *
2150 * To decide if our buffer is considered a
2151 * duplicate, we must call into the arc to determine
2152 * if multiple buffers are referencing the same
2153 * block on-disk. If so, then we simply evict
2154 * ourselves.
2155 */
2156 if (!DBUF_IS_CACHEABLE(db)) {
2157 if (db->db_blkptr != NULL &&
2158 !BP_IS_HOLE(db->db_blkptr) &&
2159 !BP_IS_EMBEDDED(db->db_blkptr)) {
2160 spa_t *spa =
2161 dmu_objset_spa(db->db_objset);
2162 blkptr_t bp = *db->db_blkptr;
2163 dbuf_clear(db);
2164 arc_freed(spa, &bp);
2165 } else {
2166 dbuf_clear(db);
2167 }
2168 } else if (arc_buf_eviction_needed(db->db_buf)) {
2169 dbuf_clear(db);
2170 } else {
2171 mutex_exit(&db->db_mtx);
2172 }
2173 }
2174 } else {
2175 mutex_exit(&db->db_mtx);
2176 }
2177 }
2178
2179 #pragma weak dmu_buf_refcount = dbuf_refcount
2180 uint64_t
2181 dbuf_refcount(dmu_buf_impl_t *db)
2182 {
2183 return (refcount_count(&db->db_holds));
2184 }
2185
2186 void *
2187 dmu_buf_set_user(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr,
2188 dmu_buf_evict_func_t *evict_func)
2189 {
2190 return (dmu_buf_update_user(db_fake, NULL, user_ptr,
2191 user_data_ptr_ptr, evict_func));
2192 }
2193
2194 void *
2195 dmu_buf_set_user_ie(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr,
2196 dmu_buf_evict_func_t *evict_func)
2197 {
2198 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2199
2200 db->db_immediate_evict = TRUE;
2201 return (dmu_buf_update_user(db_fake, NULL, user_ptr,
2202 user_data_ptr_ptr, evict_func));
2203 }
2204
2205 void *
2206 dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr, void *user_ptr,
2207 void *user_data_ptr_ptr, dmu_buf_evict_func_t *evict_func)
2208 {
2209 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2210 ASSERT(db->db_level == 0);
2211
2212 ASSERT((user_ptr == NULL) == (evict_func == NULL));
2213
2214 mutex_enter(&db->db_mtx);
2215
2216 if (db->db_user_ptr == old_user_ptr) {
2217 db->db_user_ptr = user_ptr;
2218 db->db_user_data_ptr_ptr = user_data_ptr_ptr;
2219 db->db_evict_func = evict_func;
2220
2221 dbuf_update_data(db);
2222 } else {
2223 old_user_ptr = db->db_user_ptr;
2224 }
2225
2226 mutex_exit(&db->db_mtx);
2227 return (old_user_ptr);
2228 }
2229
2230 void *
2231 dmu_buf_get_user(dmu_buf_t *db_fake)
2232 {
2233 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2234 ASSERT(!refcount_is_zero(&db->db_holds));
2235
2236 return (db->db_user_ptr);
2237 }
2238
2239 boolean_t
2240 dmu_buf_freeable(dmu_buf_t *dbuf)
2241 {
2242 boolean_t res = B_FALSE;
2243 dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf;
2244
2245 if (db->db_blkptr)
2246 res = dsl_dataset_block_freeable(db->db_objset->os_dsl_dataset,
2247 db->db_blkptr, db->db_blkptr->blk_birth);
2248
2249 return (res);
2250 }
2251
2252 blkptr_t *
2253 dmu_buf_get_blkptr(dmu_buf_t *db)
2254 {
2255 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
2256 return (dbi->db_blkptr);
2257 }
2258
2259 static void
2260 dbuf_check_blkptr(dnode_t *dn, dmu_buf_impl_t *db)
2261 {
2262 /* ASSERT(dmu_tx_is_syncing(tx) */
2263 ASSERT(MUTEX_HELD(&db->db_mtx));
2264
2265 if (db->db_blkptr != NULL)
2266 return;
2267
2268 if (db->db_blkid == DMU_SPILL_BLKID) {
2269 db->db_blkptr = &dn->dn_phys->dn_spill;
2270 BP_ZERO(db->db_blkptr);
2271 return;
2272 }
2273 if (db->db_level == dn->dn_phys->dn_nlevels-1) {
2274 /*
2275 * This buffer was allocated at a time when there was
2276 * no available blkptrs from the dnode, or it was
2277 * inappropriate to hook it in (i.e., nlevels mis-match).
2278 */
2279 ASSERT(db->db_blkid < dn->dn_phys->dn_nblkptr);
2280 ASSERT(db->db_parent == NULL);
2281 db->db_parent = dn->dn_dbuf;
2282 db->db_blkptr = &dn->dn_phys->dn_blkptr[db->db_blkid];
2283 DBUF_VERIFY(db);
2284 } else {
2285 dmu_buf_impl_t *parent = db->db_parent;
2286 int epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2287
2288 ASSERT(dn->dn_phys->dn_nlevels > 1);
2289 if (parent == NULL) {
2290 mutex_exit(&db->db_mtx);
2291 rw_enter(&dn->dn_struct_rwlock, RW_READER);
2292 (void) dbuf_hold_impl(dn, db->db_level+1,
2293 db->db_blkid >> epbs, FALSE, db, &parent);
2294 rw_exit(&dn->dn_struct_rwlock);
2295 mutex_enter(&db->db_mtx);
2296 db->db_parent = parent;
2297 }
2298 db->db_blkptr = (blkptr_t *)parent->db.db_data +
2299 (db->db_blkid & ((1ULL << epbs) - 1));
2300 DBUF_VERIFY(db);
2301 }
2302 }
2303
2304 static void
2305 dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
2306 {
2307 dmu_buf_impl_t *db = dr->dr_dbuf;
2308 dnode_t *dn;
2309 zio_t *zio;
2310
2311 ASSERT(dmu_tx_is_syncing(tx));
2312
2313 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
2314
2315 mutex_enter(&db->db_mtx);
2316
2317 ASSERT(db->db_level > 0);
2318 DBUF_VERIFY(db);
2319
2320 /* Read the block if it hasn't been read yet. */
2321 if (db->db_buf == NULL) {
2322 mutex_exit(&db->db_mtx);
2323 (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED);
2324 mutex_enter(&db->db_mtx);
2325 }
2326 ASSERT3U(db->db_state, ==, DB_CACHED);
2327 ASSERT(db->db_buf != NULL);
2328
2329 DB_DNODE_ENTER(db);
2330 dn = DB_DNODE(db);
2331 /* Indirect block size must match what the dnode thinks it is. */
2332 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2333 dbuf_check_blkptr(dn, db);
2334 DB_DNODE_EXIT(db);
2335
2336 /* Provide the pending dirty record to child dbufs */
2337 db->db_data_pending = dr;
2338
2339 mutex_exit(&db->db_mtx);
2340 dbuf_write(dr, db->db_buf, tx);
2341
2342 zio = dr->dr_zio;
2343 mutex_enter(&dr->dt.di.dr_mtx);
2344 dbuf_sync_list(&dr->dt.di.dr_children, tx);
2345 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
2346 mutex_exit(&dr->dt.di.dr_mtx);
2347 zio_nowait(zio);
2348 }
2349
2350 static void
2351 dbuf_sync_leaf(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
2352 {
2353 arc_buf_t **datap = &dr->dt.dl.dr_data;
2354 dmu_buf_impl_t *db = dr->dr_dbuf;
2355 dnode_t *dn;
2356 objset_t *os;
2357 uint64_t txg = tx->tx_txg;
2358
2359 ASSERT(dmu_tx_is_syncing(tx));
2360
2361 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
2362
2363 mutex_enter(&db->db_mtx);
2364 /*
2365 * To be synced, we must be dirtied. But we
2366 * might have been freed after the dirty.
2367 */
2368 if (db->db_state == DB_UNCACHED) {
2369 /* This buffer has been freed since it was dirtied */
2370 ASSERT(db->db.db_data == NULL);
2371 } else if (db->db_state == DB_FILL) {
2372 /* This buffer was freed and is now being re-filled */
2373 ASSERT(db->db.db_data != dr->dt.dl.dr_data);
2374 } else {
2375 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_NOFILL);
2376 }
2377 DBUF_VERIFY(db);
2378
2379 DB_DNODE_ENTER(db);
2380 dn = DB_DNODE(db);
2381
2382 if (db->db_blkid == DMU_SPILL_BLKID) {
2383 mutex_enter(&dn->dn_mtx);
2384 dn->dn_phys->dn_flags |= DNODE_FLAG_SPILL_BLKPTR;
2385 mutex_exit(&dn->dn_mtx);
2386 }
2387
2388 /*
2389 * If this is a bonus buffer, simply copy the bonus data into the
2390 * dnode. It will be written out when the dnode is synced (and it
2391 * will be synced, since it must have been dirty for dbuf_sync to
2392 * be called).
2393 */
2394 if (db->db_blkid == DMU_BONUS_BLKID) {
2395 dbuf_dirty_record_t **drp;
2396
2397 ASSERT(*datap != NULL);
2398 ASSERT0(db->db_level);
2399 ASSERT3U(dn->dn_phys->dn_bonuslen, <=, DN_MAX_BONUSLEN);
2400 bcopy(*datap, DN_BONUS(dn->dn_phys), dn->dn_phys->dn_bonuslen);
2401 DB_DNODE_EXIT(db);
2402
2403 if (*datap != db->db.db_data) {
2404 zio_buf_free(*datap, DN_MAX_BONUSLEN);
2405 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
2406 }
2407 db->db_data_pending = NULL;
2408 drp = &db->db_last_dirty;
2409 while (*drp != dr)
2410 drp = &(*drp)->dr_next;
2411 ASSERT(dr->dr_next == NULL);
2412 ASSERT(dr->dr_dbuf == db);
2413 *drp = dr->dr_next;
2414 kmem_free(dr, sizeof (dbuf_dirty_record_t));
2415 ASSERT(db->db_dirtycnt > 0);
2416 db->db_dirtycnt -= 1;
2417 dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg);
2418 return;
2419 }
2420
2421 os = dn->dn_objset;
2422
2423 /*
2424 * This function may have dropped the db_mtx lock allowing a dmu_sync
2425 * operation to sneak in. As a result, we need to ensure that we
2426 * don't check the dr_override_state until we have returned from
2427 * dbuf_check_blkptr.
2428 */
2429 dbuf_check_blkptr(dn, db);
2430
2431 /*
2432 * If this buffer is in the middle of an immediate write,
2433 * wait for the synchronous IO to complete.
2434 */
2435 while (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC) {
2436 ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
2437 cv_wait(&db->db_changed, &db->db_mtx);
2438 ASSERT(dr->dt.dl.dr_override_state != DR_NOT_OVERRIDDEN);
2439 }
2440
2441 if (db->db_state != DB_NOFILL &&
2442 dn->dn_object != DMU_META_DNODE_OBJECT &&
2443 refcount_count(&db->db_holds) > 1 &&
2444 dr->dt.dl.dr_override_state != DR_OVERRIDDEN &&
2445 *datap == db->db_buf) {
2446 /*
2447 * If this buffer is currently "in use" (i.e., there
2448 * are active holds and db_data still references it),
2449 * then make a copy before we start the write so that
2450 * any modifications from the open txg will not leak
2451 * into this write.
2452 *
2453 * NOTE: this copy does not need to be made for
2454 * objects only modified in the syncing context (e.g.
2455 * DNONE_DNODE blocks).
2456 */
2457 int blksz = arc_buf_size(*datap);
2458 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
2459 *datap = arc_buf_alloc(os->os_spa, blksz, db, type);
2460 bcopy(db->db.db_data, (*datap)->b_data, blksz);
2461 }
2462 db->db_data_pending = dr;
2463
2464 mutex_exit(&db->db_mtx);
2465
2466 dbuf_write(dr, *datap, tx);
2467
2468 ASSERT(!list_link_active(&dr->dr_dirty_node));
2469 if (dn->dn_object == DMU_META_DNODE_OBJECT) {
2470 list_insert_tail(&dn->dn_dirty_records[txg&TXG_MASK], dr);
2471 DB_DNODE_EXIT(db);
2472 } else {
2473 /*
2474 * Although zio_nowait() does not "wait for an IO", it does
2475 * initiate the IO. If this is an empty write it seems plausible
2476 * that the IO could actually be completed before the nowait
2477 * returns. We need to DB_DNODE_EXIT() first in case
2478 * zio_nowait() invalidates the dbuf.
2479 */
2480 DB_DNODE_EXIT(db);
2481 zio_nowait(dr->dr_zio);
2482 }
2483 }
2484
2485 void
2486 dbuf_sync_list(list_t *list, dmu_tx_t *tx)
2487 {
2488 dbuf_dirty_record_t *dr;
2489
2490 while (dr = list_head(list)) {
2491 if (dr->dr_zio != NULL) {
2492 /*
2493 * If we find an already initialized zio then we
2494 * are processing the meta-dnode, and we have finished.
2495 * The dbufs for all dnodes are put back on the list
2496 * during processing, so that we can zio_wait()
2497 * these IOs after initiating all child IOs.
2498 */
2499 ASSERT3U(dr->dr_dbuf->db.db_object, ==,
2500 DMU_META_DNODE_OBJECT);
2501 break;
2502 }
2503 list_remove(list, dr);
2504 if (dr->dr_dbuf->db_level > 0)
2505 dbuf_sync_indirect(dr, tx);
2506 else
2507 dbuf_sync_leaf(dr, tx);
2508 }
2509 }
2510
2511 /* ARGSUSED */
2512 static void
2513 dbuf_write_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
2514 {
2515 dmu_buf_impl_t *db = vdb;
2516 dnode_t *dn;
2517 blkptr_t *bp = zio->io_bp;
2518 blkptr_t *bp_orig = &zio->io_bp_orig;
2519 spa_t *spa = zio->io_spa;
2520 int64_t delta;
2521 uint64_t fill = 0;
2522 int i;
2523
2524 ASSERT3P(db->db_blkptr, ==, bp);
2525
2526 DB_DNODE_ENTER(db);
2527 dn = DB_DNODE(db);
2528 delta = bp_get_dsize_sync(spa, bp) - bp_get_dsize_sync(spa, bp_orig);
2529 dnode_diduse_space(dn, delta - zio->io_prev_space_delta);
2530 zio->io_prev_space_delta = delta;
2531
2532 if (bp->blk_birth != 0) {
2533 ASSERT((db->db_blkid != DMU_SPILL_BLKID &&
2534 BP_GET_TYPE(bp) == dn->dn_type) ||
2535 (db->db_blkid == DMU_SPILL_BLKID &&
2536 BP_GET_TYPE(bp) == dn->dn_bonustype) ||
2537 BP_IS_EMBEDDED(bp));
2538 ASSERT(BP_GET_LEVEL(bp) == db->db_level);
2539 }
2540
2541 mutex_enter(&db->db_mtx);
2542
2543 #ifdef ZFS_DEBUG
2544 if (db->db_blkid == DMU_SPILL_BLKID) {
2545 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
2546 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
2547 db->db_blkptr == &dn->dn_phys->dn_spill);
2548 }
2549 #endif
2550
2551 if (db->db_level == 0) {
2552 mutex_enter(&dn->dn_mtx);
2553 if (db->db_blkid > dn->dn_phys->dn_maxblkid &&
2554 db->db_blkid != DMU_SPILL_BLKID)
2555 dn->dn_phys->dn_maxblkid = db->db_blkid;
2556 mutex_exit(&dn->dn_mtx);
2557
2558 if (dn->dn_type == DMU_OT_DNODE) {
2559 dnode_phys_t *dnp = db->db.db_data;
2560 for (i = db->db.db_size >> DNODE_SHIFT; i > 0;
2561 i--, dnp++) {
2562 if (dnp->dn_type != DMU_OT_NONE)
2563 fill++;
2564 }
2565 } else {
2566 if (BP_IS_HOLE(bp)) {
2567 fill = 0;
2568 } else {
2569 fill = 1;
2570 }
2571 }
2572 } else {
2573 blkptr_t *ibp = db->db.db_data;
2574 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2575 for (i = db->db.db_size >> SPA_BLKPTRSHIFT; i > 0; i--, ibp++) {
2576 if (BP_IS_HOLE(ibp))
2577 continue;
2578 fill += BP_GET_FILL(ibp);
2579 }
2580 }
2581 DB_DNODE_EXIT(db);
2582
2583 if (!BP_IS_EMBEDDED(bp))
2584 bp->blk_fill = fill;
2585
2586 mutex_exit(&db->db_mtx);
2587 }
2588
2589 /*
2590 * The SPA will call this callback several times for each zio - once
2591 * for every physical child i/o (zio->io_phys_children times). This
2592 * allows the DMU to monitor the progress of each logical i/o. For example,
2593 * there may be 2 copies of an indirect block, or many fragments of a RAID-Z
2594 * block. There may be a long delay before all copies/fragments are completed,
2595 * so this callback allows us to retire dirty space gradually, as the physical
2596 * i/os complete.
2597 */
2598 /* ARGSUSED */
2599 static void
2600 dbuf_write_physdone(zio_t *zio, arc_buf_t *buf, void *arg)
2601 {
2602 dmu_buf_impl_t *db = arg;
2603 objset_t *os = db->db_objset;
2604 dsl_pool_t *dp = dmu_objset_pool(os);
2605 dbuf_dirty_record_t *dr;
2606 int delta = 0;
2607
2608 dr = db->db_data_pending;
2609 ASSERT3U(dr->dr_txg, ==, zio->io_txg);
2610
2611 /*
2612 * The callback will be called io_phys_children times. Retire one
2613 * portion of our dirty space each time we are called. Any rounding
2614 * error will be cleaned up by dsl_pool_sync()'s call to
2615 * dsl_pool_undirty_space().
2616 */
2617 delta = dr->dr_accounted / zio->io_phys_children;
2618 dsl_pool_undirty_space(dp, delta, zio->io_txg);
2619 }
2620
2621 /* ARGSUSED */
2622 static void
2623 dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb)
2624 {
2625 dmu_buf_impl_t *db = vdb;
2626 blkptr_t *bp_orig = &zio->io_bp_orig;
2627 blkptr_t *bp = db->db_blkptr;
2628 objset_t *os = db->db_objset;
2629 dmu_tx_t *tx = os->os_synctx;
2630 dbuf_dirty_record_t **drp, *dr;
2631
2632 ASSERT0(zio->io_error);
2633 ASSERT(db->db_blkptr == bp);
2634
2635 /*
2636 * For nopwrites and rewrites we ensure that the bp matches our
2637 * original and bypass all the accounting.
2638 */
2639 if (zio->io_flags & (ZIO_FLAG_IO_REWRITE | ZIO_FLAG_NOPWRITE)) {
2640 ASSERT(BP_EQUAL(bp, bp_orig));
2641 } else {
2642 dsl_dataset_t *ds = os->os_dsl_dataset;
2643 (void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE);
2644 dsl_dataset_block_born(ds, bp, tx);
2645 }
2646
2647 mutex_enter(&db->db_mtx);
2648
2649 DBUF_VERIFY(db);
2650
2651 drp = &db->db_last_dirty;
2652 while ((dr = *drp) != db->db_data_pending)
2653 drp = &dr->dr_next;
2654 ASSERT(!list_link_active(&dr->dr_dirty_node));
2655 ASSERT(dr->dr_dbuf == db);
2656 ASSERT(dr->dr_next == NULL);
2657 *drp = dr->dr_next;
2658
2659 #ifdef ZFS_DEBUG
2660 if (db->db_blkid == DMU_SPILL_BLKID) {
2661 dnode_t *dn;
2662
2663 DB_DNODE_ENTER(db);
2664 dn = DB_DNODE(db);
2665 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
2666 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
2667 db->db_blkptr == &dn->dn_phys->dn_spill);
2668 DB_DNODE_EXIT(db);
2669 }
2670 #endif
2671
2672 if (db->db_level == 0) {
2673 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
2674 ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
2675 if (db->db_state != DB_NOFILL) {
2676 if (dr->dt.dl.dr_data != db->db_buf)
2677 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data,
2678 db));
2679 else if (!arc_released(db->db_buf))
2680 arc_set_callback(db->db_buf, dbuf_do_evict, db);
2681 }
2682 } else {
2683 dnode_t *dn;
2684
2685 DB_DNODE_ENTER(db);
2686 dn = DB_DNODE(db);
2687 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
2688 ASSERT3U(db->db.db_size, ==, 1 << dn->dn_phys->dn_indblkshift);
2689 if (!BP_IS_HOLE(db->db_blkptr)) {
2690 int epbs =
2691 dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2692 ASSERT3U(db->db_blkid, <=,
2693 dn->dn_phys->dn_maxblkid >> (db->db_level * epbs));
2694 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==,
2695 db->db.db_size);
2696 if (!arc_released(db->db_buf))
2697 arc_set_callback(db->db_buf, dbuf_do_evict, db);
2698 }
2699 DB_DNODE_EXIT(db);
2700 mutex_destroy(&dr->dt.di.dr_mtx);
2701 list_destroy(&dr->dt.di.dr_children);
2702 }
2703 kmem_free(dr, sizeof (dbuf_dirty_record_t));
2704
2705 cv_broadcast(&db->db_changed);
2706 ASSERT(db->db_dirtycnt > 0);
2707 db->db_dirtycnt -= 1;
2708 db->db_data_pending = NULL;
2709 dbuf_rele_and_unlock(db, (void *)(uintptr_t)tx->tx_txg);
2710 }
2711
2712 static void
2713 dbuf_write_nofill_ready(zio_t *zio)
2714 {
2715 dbuf_write_ready(zio, NULL, zio->io_private);
2716 }
2717
2718 static void
2719 dbuf_write_nofill_done(zio_t *zio)
2720 {
2721 dbuf_write_done(zio, NULL, zio->io_private);
2722 }
2723
2724 static void
2725 dbuf_write_override_ready(zio_t *zio)
2726 {
2727 dbuf_dirty_record_t *dr = zio->io_private;
2728 dmu_buf_impl_t *db = dr->dr_dbuf;
2729
2730 dbuf_write_ready(zio, NULL, db);
2731 }
2732
2733 static void
2734 dbuf_write_override_done(zio_t *zio)
2735 {
2736 dbuf_dirty_record_t *dr = zio->io_private;
2737 dmu_buf_impl_t *db = dr->dr_dbuf;
2738 blkptr_t *obp = &dr->dt.dl.dr_overridden_by;
2739
2740 mutex_enter(&db->db_mtx);
2741 if (!BP_EQUAL(zio->io_bp, obp)) {
2742 if (!BP_IS_HOLE(obp))
2743 dsl_free(spa_get_dsl(zio->io_spa), zio->io_txg, obp);
2744 arc_release(dr->dt.dl.dr_data, db);
2745 }
2746 mutex_exit(&db->db_mtx);
2747
2748 dbuf_write_done(zio, NULL, db);
2749 }
2750
2751 /* Issue I/O to commit a dirty buffer to disk. */
2752 static void
2753 dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx)
2754 {
2755 dmu_buf_impl_t *db = dr->dr_dbuf;
2756 dnode_t *dn;
2757 objset_t *os;
2758 dmu_buf_impl_t *parent = db->db_parent;
2759 uint64_t txg = tx->tx_txg;
2760 zbookmark_phys_t zb;
2761 zio_prop_t zp;
2762 zio_t *zio;
2763 int wp_flag = 0;
2764
2765 DB_DNODE_ENTER(db);
2766 dn = DB_DNODE(db);
2767 os = dn->dn_objset;
2768
2769 if (db->db_state != DB_NOFILL) {
2770 if (db->db_level > 0 || dn->dn_type == DMU_OT_DNODE) {
2771 /*
2772 * Private object buffers are released here rather
2773 * than in dbuf_dirty() since they are only modified
2774 * in the syncing context and we don't want the
2775 * overhead of making multiple copies of the data.
2776 */
2777 if (BP_IS_HOLE(db->db_blkptr)) {
2778 arc_buf_thaw(data);
2779 } else {
2780 dbuf_release_bp(db);
2781 }
2782 }
2783 }
2784
2785 if (parent != dn->dn_dbuf) {
2786 /* Our parent is an indirect block. */
2787 /* We have a dirty parent that has been scheduled for write. */
2788 ASSERT(parent && parent->db_data_pending);
2789 /* Our parent's buffer is one level closer to the dnode. */
2790 ASSERT(db->db_level == parent->db_level-1);
2791 /*
2792 * We're about to modify our parent's db_data by modifying
2793 * our block pointer, so the parent must be released.
2794 */
2795 ASSERT(arc_released(parent->db_buf));
2796 zio = parent->db_data_pending->dr_zio;
2797 } else {
2798 /* Our parent is the dnode itself. */
2799 ASSERT((db->db_level == dn->dn_phys->dn_nlevels-1 &&
2800 db->db_blkid != DMU_SPILL_BLKID) ||
2801 (db->db_blkid == DMU_SPILL_BLKID && db->db_level == 0));
2802 if (db->db_blkid != DMU_SPILL_BLKID)
2803 ASSERT3P(db->db_blkptr, ==,
2804 &dn->dn_phys->dn_blkptr[db->db_blkid]);
2805 zio = dn->dn_zio;
2806 }
2807
2808 ASSERT(db->db_level == 0 || data == db->db_buf);
2809 ASSERT3U(db->db_blkptr->blk_birth, <=, txg);
2810 ASSERT(zio);
2811
2812 SET_BOOKMARK(&zb, os->os_dsl_dataset ?
2813 os->os_dsl_dataset->ds_object : DMU_META_OBJSET,
2814 db->db.db_object, db->db_level, db->db_blkid);
2815
2816 if (db->db_blkid == DMU_SPILL_BLKID)
2817 wp_flag = WP_SPILL;
2818 wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0;
2819
2820 dmu_write_policy(os, dn, db->db_level, wp_flag, &zp);
2821 DB_DNODE_EXIT(db);
2822
2823 if (db->db_level == 0 &&
2824 dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
2825 /*
2826 * The BP for this block has been provided by open context
2827 * (by dmu_sync() or dmu_buf_write_embedded()).
2828 */
2829 void *contents = (data != NULL) ? data->b_data : NULL;
2830
2831 dr->dr_zio = zio_write(zio, os->os_spa, txg,
2832 db->db_blkptr, contents, db->db.db_size, &zp,
2833 dbuf_write_override_ready, NULL, dbuf_write_override_done,
2834 dr, ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
2835 mutex_enter(&db->db_mtx);
2836 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
2837 zio_write_override(dr->dr_zio, &dr->dt.dl.dr_overridden_by,
2838 dr->dt.dl.dr_copies, dr->dt.dl.dr_nopwrite);
2839 mutex_exit(&db->db_mtx);
2840 } else if (db->db_state == DB_NOFILL) {
2841 ASSERT(zp.zp_checksum == ZIO_CHECKSUM_OFF ||
2842 zp.zp_checksum == ZIO_CHECKSUM_NOPARITY);
2843 dr->dr_zio = zio_write(zio, os->os_spa, txg,
2844 db->db_blkptr, NULL, db->db.db_size, &zp,
2845 dbuf_write_nofill_ready, NULL, dbuf_write_nofill_done, db,
2846 ZIO_PRIORITY_ASYNC_WRITE,
2847 ZIO_FLAG_MUSTSUCCEED | ZIO_FLAG_NODATA, &zb);
2848 } else {
2849 ASSERT(arc_released(data));
2850 dr->dr_zio = arc_write(zio, os->os_spa, txg,
2851 db->db_blkptr, data, DBUF_IS_L2CACHEABLE(db),
2852 DBUF_IS_L2COMPRESSIBLE(db), &zp, dbuf_write_ready,
2853 dbuf_write_physdone, dbuf_write_done, db,
2854 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
2855 }
2856 }