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 2018 Nexenta Systems, Inc. All rights reserved.
24 * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
25 * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
26 * Copyright (c) 2013, Joyent, Inc. All rights reserved.
27 * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
28 * Copyright (c) 2014 Integros [integros.com]
29 */
30
31 #include <sys/zfs_context.h>
32 #include <sys/dmu.h>
33 #include <sys/dmu_send.h>
34 #include <sys/dmu_impl.h>
35 #include <sys/dbuf.h>
36 #include <sys/dmu_objset.h>
37 #include <sys/dsl_dataset.h>
38 #include <sys/dsl_dir.h>
39 #include <sys/dmu_tx.h>
40 #include <sys/spa.h>
41 #include <sys/spa_impl.h>
42 #include <sys/zio.h>
43 #include <sys/dmu_zfetch.h>
44 #include <sys/sa.h>
45 #include <sys/sa_impl.h>
46 #include <sys/zfeature.h>
47 #include <sys/blkptr.h>
48 #include <sys/range_tree.h>
49 #include <sys/callb.h>
50 #include <sys/abd.h>
51
52 uint_t zfs_dbuf_evict_key;
53
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 #ifndef __lint
58 extern inline void dmu_buf_init_user(dmu_buf_user_t *dbu,
59 dmu_buf_evict_func_t *evict_func_sync,
60 dmu_buf_evict_func_t *evict_func_async,
61 dmu_buf_t **clear_on_evict_dbufp);
62 #endif /* ! __lint */
63
64 /*
65 * Global data structures and functions for the dbuf cache.
66 */
67 static kmem_cache_t *dbuf_kmem_cache;
68 static taskq_t *dbu_evict_taskq;
69
70 static kthread_t *dbuf_cache_evict_thread;
71 static kmutex_t dbuf_evict_lock;
72 static kcondvar_t dbuf_evict_cv;
73 static boolean_t dbuf_evict_thread_exit;
74
75 /*
76 * There are two dbuf caches; each dbuf can only be in one of them at a time.
77 *
78 * 1. Cache of metadata dbufs, to help make read-heavy administrative commands
79 * from /sbin/zfs run faster. The "metadata cache" specifically stores dbufs
80 * that represent the metadata that describes filesystems/snapshots/
81 * bookmarks/properties/etc. We only evict from this cache when we export a
82 * pool, to short-circuit as much I/O as possible for all administrative
83 * commands that need the metadata. There is no eviction policy for this
84 * cache, because we try to only include types in it which would occupy a
85 * very small amount of space per object but create a large impact on the
86 * performance of these commands. Instead, after it reaches a maximum size
87 * (which should only happen on very small memory systems with a very large
88 * number of filesystem objects), we stop taking new dbufs into the
89 * metadata cache, instead putting them in the normal dbuf cache.
90 *
91 * 2. LRU cache of dbufs. The "dbuf cache" maintains a list of dbufs that
92 * are not currently held but have been recently released. These dbufs
93 * are not eligible for arc eviction until they are aged out of the cache.
94 * Dbufs that are aged out of the cache will be immediately destroyed and
95 * become eligible for arc eviction.
96 *
97 * Dbufs are added to these caches once the last hold is released. If a dbuf is
98 * later accessed and still exists in the dbuf cache, then it will be removed
99 * from the cache and later re-added to the head of the cache.
100 *
101 * If a given dbuf meets the requirements for the metadata cache, it will go
102 * there, otherwise it will be considered for the generic LRU dbuf cache. The
103 * caches and the refcounts tracking their sizes are stored in an array indexed
104 * by those caches' matching enum values (from dbuf_cached_state_t).
105 */
106 typedef struct dbuf_cache {
107 multilist_t *cache;
108 refcount_t size;
109 } dbuf_cache_t;
110 dbuf_cache_t dbuf_caches[DB_CACHE_MAX];
111
112 /* Size limits for the caches */
113 uint64_t dbuf_cache_max_bytes = 0;
114 uint64_t dbuf_metadata_cache_max_bytes = 0;
115 /* Set the default sizes of the caches to log2 fraction of arc size */
116 int dbuf_cache_shift = 5;
117 int dbuf_metadata_cache_shift = 6;
118
119 /*
120 * For diagnostic purposes, this is incremented whenever we can't add
121 * something to the metadata cache because it's full, and instead put
122 * the data in the regular dbuf cache.
123 */
124 uint64_t dbuf_metadata_cache_overflow;
125
126 /*
127 * The LRU dbuf cache uses a three-stage eviction policy:
128 * - A low water marker designates when the dbuf eviction thread
129 * should stop evicting from the dbuf cache.
130 * - When we reach the maximum size (aka mid water mark), we
131 * signal the eviction thread to run.
132 * - The high water mark indicates when the eviction thread
133 * is unable to keep up with the incoming load and eviction must
134 * happen in the context of the calling thread.
135 *
136 * The dbuf cache:
137 * (max size)
138 * low water mid water hi water
139 * +----------------------------------------+----------+----------+
140 * | | | |
141 * | | | |
142 * | | | |
143 * | | | |
144 * +----------------------------------------+----------+----------+
145 * stop signal evict
146 * evicting eviction directly
147 * thread
148 *
149 * The high and low water marks indicate the operating range for the eviction
150 * thread. The low water mark is, by default, 90% of the total size of the
151 * cache and the high water mark is at 110% (both of these percentages can be
152 * changed by setting dbuf_cache_lowater_pct and dbuf_cache_hiwater_pct,
153 * respectively). The eviction thread will try to ensure that the cache remains
154 * within this range by waking up every second and checking if the cache is
155 * above the low water mark. The thread can also be woken up by callers adding
156 * elements into the cache if the cache is larger than the mid water (i.e max
157 * cache size). Once the eviction thread is woken up and eviction is required,
158 * it will continue evicting buffers until it's able to reduce the cache size
159 * to the low water mark. If the cache size continues to grow and hits the high
160 * water mark, then callers adding elments to the cache will begin to evict
161 * directly from the cache until the cache is no longer above the high water
162 * mark.
163 */
164
165 /*
166 * The percentage above and below the maximum cache size.
167 */
168 uint_t dbuf_cache_hiwater_pct = 10;
169 uint_t dbuf_cache_lowater_pct = 10;
170
171 /* ARGSUSED */
172 static int
173 dbuf_cons(void *vdb, void *unused, int kmflag)
174 {
175 dmu_buf_impl_t *db = vdb;
176 bzero(db, sizeof (dmu_buf_impl_t));
177
178 mutex_init(&db->db_mtx, NULL, MUTEX_DEFAULT, NULL);
179 cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL);
180 multilist_link_init(&db->db_cache_link);
181 refcount_create(&db->db_holds);
182
183 return (0);
184 }
185
186 /* ARGSUSED */
187 static void
188 dbuf_dest(void *vdb, void *unused)
189 {
190 dmu_buf_impl_t *db = vdb;
191 mutex_destroy(&db->db_mtx);
192 cv_destroy(&db->db_changed);
193 ASSERT(!multilist_link_active(&db->db_cache_link));
194 refcount_destroy(&db->db_holds);
195 }
196
197 /*
198 * dbuf hash table routines
199 */
200 #pragma align 64(dbuf_hash_table)
201 static dbuf_hash_table_t dbuf_hash_table;
202
203 static uint64_t dbuf_hash_count;
204
205 static uint64_t
206 dbuf_hash(void *os, uint64_t obj, uint8_t lvl, uint64_t blkid)
207 {
208 uintptr_t osv = (uintptr_t)os;
209 uint64_t crc = -1ULL;
210
211 ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY);
212 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (lvl)) & 0xFF];
213 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (osv >> 6)) & 0xFF];
214 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 0)) & 0xFF];
215 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 8)) & 0xFF];
216 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 0)) & 0xFF];
217 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 8)) & 0xFF];
218
219 crc ^= (osv>>14) ^ (obj>>16) ^ (blkid>>16);
220
221 return (crc);
222 }
223
224 #define DBUF_EQUAL(dbuf, os, obj, level, blkid) \
225 ((dbuf)->db.db_object == (obj) && \
226 (dbuf)->db_objset == (os) && \
227 (dbuf)->db_level == (level) && \
228 (dbuf)->db_blkid == (blkid))
229
230 dmu_buf_impl_t *
231 dbuf_find(objset_t *os, uint64_t obj, uint8_t level, uint64_t blkid)
232 {
233 dbuf_hash_table_t *h = &dbuf_hash_table;
234 uint64_t hv = dbuf_hash(os, obj, level, blkid);
235 uint64_t idx = hv & h->hash_table_mask;
236 dmu_buf_impl_t *db;
237
238 mutex_enter(DBUF_HASH_MUTEX(h, idx));
239 for (db = h->hash_table[idx]; db != NULL; db = db->db_hash_next) {
240 if (DBUF_EQUAL(db, os, obj, level, blkid)) {
241 mutex_enter(&db->db_mtx);
242 if (db->db_state != DB_EVICTING) {
243 mutex_exit(DBUF_HASH_MUTEX(h, idx));
244 return (db);
245 }
246 mutex_exit(&db->db_mtx);
247 }
248 }
249 mutex_exit(DBUF_HASH_MUTEX(h, idx));
250 return (NULL);
251 }
252
253 static dmu_buf_impl_t *
254 dbuf_find_bonus(objset_t *os, uint64_t object)
255 {
256 dnode_t *dn;
257 dmu_buf_impl_t *db = NULL;
258
259 if (dnode_hold(os, object, FTAG, &dn) == 0) {
260 rw_enter(&dn->dn_struct_rwlock, RW_READER);
261 if (dn->dn_bonus != NULL) {
262 db = dn->dn_bonus;
263 mutex_enter(&db->db_mtx);
264 }
265 rw_exit(&dn->dn_struct_rwlock);
266 dnode_rele(dn, FTAG);
267 }
268 return (db);
269 }
270
271 /*
272 * Insert an entry into the hash table. If there is already an element
273 * equal to elem in the hash table, then the already existing element
274 * will be returned and the new element will not be inserted.
275 * Otherwise returns NULL.
276 */
277 static dmu_buf_impl_t *
278 dbuf_hash_insert(dmu_buf_impl_t *db)
279 {
280 dbuf_hash_table_t *h = &dbuf_hash_table;
281 objset_t *os = db->db_objset;
282 uint64_t obj = db->db.db_object;
283 int level = db->db_level;
284 uint64_t blkid = db->db_blkid;
285 uint64_t hv = dbuf_hash(os, obj, level, blkid);
286 uint64_t idx = hv & h->hash_table_mask;
287 dmu_buf_impl_t *dbf;
288
289 mutex_enter(DBUF_HASH_MUTEX(h, idx));
290 for (dbf = h->hash_table[idx]; dbf != NULL; dbf = dbf->db_hash_next) {
291 if (DBUF_EQUAL(dbf, os, obj, level, blkid)) {
292 mutex_enter(&dbf->db_mtx);
293 if (dbf->db_state != DB_EVICTING) {
294 mutex_exit(DBUF_HASH_MUTEX(h, idx));
295 return (dbf);
296 }
297 mutex_exit(&dbf->db_mtx);
298 }
299 }
300
301 mutex_enter(&db->db_mtx);
302 db->db_hash_next = h->hash_table[idx];
303 h->hash_table[idx] = db;
304 mutex_exit(DBUF_HASH_MUTEX(h, idx));
305 atomic_inc_64(&dbuf_hash_count);
306
307 return (NULL);
308 }
309
310 /*
311 * Remove an entry from the hash table. It must be in the EVICTING state.
312 */
313 static void
314 dbuf_hash_remove(dmu_buf_impl_t *db)
315 {
316 dbuf_hash_table_t *h = &dbuf_hash_table;
317 uint64_t hv = dbuf_hash(db->db_objset, db->db.db_object,
318 db->db_level, db->db_blkid);
319 uint64_t idx = hv & h->hash_table_mask;
320 dmu_buf_impl_t *dbf, **dbp;
321
322 /*
323 * We musn't hold db_mtx to maintain lock ordering:
324 * DBUF_HASH_MUTEX > db_mtx.
325 */
326 ASSERT(refcount_is_zero(&db->db_holds));
327 ASSERT(db->db_state == DB_EVICTING);
328 ASSERT(!MUTEX_HELD(&db->db_mtx));
329
330 mutex_enter(DBUF_HASH_MUTEX(h, idx));
331 dbp = &h->hash_table[idx];
332 while ((dbf = *dbp) != db) {
333 dbp = &dbf->db_hash_next;
334 ASSERT(dbf != NULL);
335 }
336 *dbp = db->db_hash_next;
337 db->db_hash_next = NULL;
338 mutex_exit(DBUF_HASH_MUTEX(h, idx));
339 atomic_dec_64(&dbuf_hash_count);
340 }
341
342 typedef enum {
343 DBVU_EVICTING,
344 DBVU_NOT_EVICTING
345 } dbvu_verify_type_t;
346
347 static void
348 dbuf_verify_user(dmu_buf_impl_t *db, dbvu_verify_type_t verify_type)
349 {
350 #ifdef ZFS_DEBUG
351 int64_t holds;
352
353 if (db->db_user == NULL)
354 return;
355
356 /* Only data blocks support the attachment of user data. */
357 ASSERT(db->db_level == 0);
358
359 /* Clients must resolve a dbuf before attaching user data. */
360 ASSERT(db->db.db_data != NULL);
361 ASSERT3U(db->db_state, ==, DB_CACHED);
362
363 holds = refcount_count(&db->db_holds);
364 if (verify_type == DBVU_EVICTING) {
365 /*
366 * Immediate eviction occurs when holds == dirtycnt.
367 * For normal eviction buffers, holds is zero on
368 * eviction, except when dbuf_fix_old_data() calls
369 * dbuf_clear_data(). However, the hold count can grow
370 * during eviction even though db_mtx is held (see
371 * dmu_bonus_hold() for an example), so we can only
372 * test the generic invariant that holds >= dirtycnt.
373 */
374 ASSERT3U(holds, >=, db->db_dirtycnt);
375 } else {
376 if (db->db_user_immediate_evict == TRUE)
377 ASSERT3U(holds, >=, db->db_dirtycnt);
378 else
379 ASSERT3U(holds, >, 0);
380 }
381 #endif
382 }
383
384 static void
385 dbuf_evict_user(dmu_buf_impl_t *db)
386 {
387 dmu_buf_user_t *dbu = db->db_user;
388
389 ASSERT(MUTEX_HELD(&db->db_mtx));
390
391 if (dbu == NULL)
392 return;
393
394 dbuf_verify_user(db, DBVU_EVICTING);
395 db->db_user = NULL;
396
397 #ifdef ZFS_DEBUG
398 if (dbu->dbu_clear_on_evict_dbufp != NULL)
399 *dbu->dbu_clear_on_evict_dbufp = NULL;
400 #endif
401
402 /*
403 * There are two eviction callbacks - one that we call synchronously
404 * and one that we invoke via a taskq. The async one is useful for
405 * avoiding lock order reversals and limiting stack depth.
406 *
407 * Note that if we have a sync callback but no async callback,
408 * it's likely that the sync callback will free the structure
409 * containing the dbu. In that case we need to take care to not
410 * dereference dbu after calling the sync evict func.
411 */
412 boolean_t has_async = (dbu->dbu_evict_func_async != NULL);
413
414 if (dbu->dbu_evict_func_sync != NULL)
415 dbu->dbu_evict_func_sync(dbu);
416
417 if (has_async) {
418 taskq_dispatch_ent(dbu_evict_taskq, dbu->dbu_evict_func_async,
419 dbu, 0, &dbu->dbu_tqent);
420 }
421 }
422
423 boolean_t
424 dbuf_is_metadata(dmu_buf_impl_t *db)
425 {
426 if (db->db_level > 0) {
427 return (B_TRUE);
428 } else {
429 boolean_t is_metadata;
430
431 DB_DNODE_ENTER(db);
432 is_metadata = DMU_OT_IS_METADATA(DB_DNODE(db)->dn_type);
433 DB_DNODE_EXIT(db);
434
435 return (is_metadata);
436 }
437 }
438
439 boolean_t
440 dbuf_is_ddt(dmu_buf_impl_t *db)
441 {
442 boolean_t is_ddt;
443
444 DB_DNODE_ENTER(db);
445 is_ddt = (DB_DNODE(db)->dn_type == DMU_OT_DDT_ZAP) ||
446 (DB_DNODE(db)->dn_type == DMU_OT_DDT_STATS);
447 DB_DNODE_EXIT(db);
448
449 return (is_ddt);
450 }
451
452 /*
453 * This returns whether this dbuf should be stored in the metadata cache, which
454 * is based on whether it's from one of the dnode types that store data related
455 * to traversing dataset hierarchies.
456 */
457 static boolean_t
458 dbuf_include_in_metadata_cache(dmu_buf_impl_t *db)
459 {
460 DB_DNODE_ENTER(db);
461 dmu_object_type_t type = DB_DNODE(db)->dn_type;
462 DB_DNODE_EXIT(db);
463
464 /* Check if this dbuf is one of the types we care about */
465 if (DMU_OT_IS_METADATA_CACHED(type)) {
466 /* If we hit this, then we set something up wrong in dmu_ot */
467 ASSERT(DMU_OT_IS_METADATA(type));
468
469 /*
470 * Sanity check for small-memory systems: don't allocate too
471 * much memory for this purpose.
472 */
473 if (refcount_count(&dbuf_caches[DB_DBUF_METADATA_CACHE].size) >
474 dbuf_metadata_cache_max_bytes) {
475 dbuf_metadata_cache_overflow++;
476 DTRACE_PROBE1(dbuf__metadata__cache__overflow,
477 dmu_buf_impl_t *, db);
478 return (B_FALSE);
479 }
480
481 return (B_TRUE);
482 }
483
484 return (B_FALSE);
485 }
486
487 /*
488 * This function *must* return indices evenly distributed between all
489 * sublists of the multilist. This is needed due to how the dbuf eviction
490 * code is laid out; dbuf_evict_thread() assumes dbufs are evenly
491 * distributed between all sublists and uses this assumption when
492 * deciding which sublist to evict from and how much to evict from it.
493 */
494 unsigned int
495 dbuf_cache_multilist_index_func(multilist_t *ml, void *obj)
496 {
497 dmu_buf_impl_t *db = obj;
498
499 /*
500 * The assumption here, is the hash value for a given
501 * dmu_buf_impl_t will remain constant throughout it's lifetime
502 * (i.e. it's objset, object, level and blkid fields don't change).
503 * Thus, we don't need to store the dbuf's sublist index
504 * on insertion, as this index can be recalculated on removal.
505 *
506 * Also, the low order bits of the hash value are thought to be
507 * distributed evenly. Otherwise, in the case that the multilist
508 * has a power of two number of sublists, each sublists' usage
509 * would not be evenly distributed.
510 */
511 return (dbuf_hash(db->db_objset, db->db.db_object,
512 db->db_level, db->db_blkid) %
513 multilist_get_num_sublists(ml));
514 }
515
516 static inline boolean_t
517 dbuf_cache_above_hiwater(void)
518 {
519 uint64_t dbuf_cache_hiwater_bytes =
520 (dbuf_cache_max_bytes * dbuf_cache_hiwater_pct) / 100;
521
522 return (refcount_count(&dbuf_caches[DB_DBUF_CACHE].size) >
523 dbuf_cache_max_bytes + dbuf_cache_hiwater_bytes);
524 }
525
526 static inline boolean_t
527 dbuf_cache_above_lowater(void)
528 {
529 uint64_t dbuf_cache_lowater_bytes =
530 (dbuf_cache_max_bytes * dbuf_cache_lowater_pct) / 100;
531
532 return (refcount_count(&dbuf_caches[DB_DBUF_CACHE].size) >
533 dbuf_cache_max_bytes - dbuf_cache_lowater_bytes);
534 }
535
536 /*
537 * Evict the oldest eligible dbuf from the dbuf cache.
538 */
539 static void
540 dbuf_evict_one(void)
541 {
542 int idx = multilist_get_random_index(dbuf_caches[DB_DBUF_CACHE].cache);
543 multilist_sublist_t *mls = multilist_sublist_lock(
544 dbuf_caches[DB_DBUF_CACHE].cache, idx);
545
546 ASSERT(!MUTEX_HELD(&dbuf_evict_lock));
547
548 /*
549 * Set the thread's tsd to indicate that it's processing evictions.
550 * Once a thread stops evicting from the dbuf cache it will
551 * reset its tsd to NULL.
552 */
553 ASSERT3P(tsd_get(zfs_dbuf_evict_key), ==, NULL);
554 (void) tsd_set(zfs_dbuf_evict_key, (void *)B_TRUE);
555
556 dmu_buf_impl_t *db = multilist_sublist_tail(mls);
557 while (db != NULL && mutex_tryenter(&db->db_mtx) == 0) {
558 db = multilist_sublist_prev(mls, db);
559 }
560
561 DTRACE_PROBE2(dbuf__evict__one, dmu_buf_impl_t *, db,
562 multilist_sublist_t *, mls);
563
564 if (db != NULL) {
565 multilist_sublist_remove(mls, db);
566 multilist_sublist_unlock(mls);
567 (void) refcount_remove_many(&dbuf_caches[DB_DBUF_CACHE].size,
568 db->db.db_size, db);
569 ASSERT3U(db->db_caching_status, ==, DB_DBUF_CACHE);
570 db->db_caching_status = DB_NO_CACHE;
571 dbuf_destroy(db);
572 } else {
573 multilist_sublist_unlock(mls);
574 }
575 (void) tsd_set(zfs_dbuf_evict_key, NULL);
576 }
577
578 /*
579 * The dbuf evict thread is responsible for aging out dbufs from the
580 * cache. Once the cache has reached it's maximum size, dbufs are removed
581 * and destroyed. The eviction thread will continue running until the size
582 * of the dbuf cache is at or below the maximum size. Once the dbuf is aged
583 * out of the cache it is destroyed and becomes eligible for arc eviction.
584 */
585 /* ARGSUSED */
586 static void
587 dbuf_evict_thread(void *unused)
588 {
589 callb_cpr_t cpr;
590
591 CALLB_CPR_INIT(&cpr, &dbuf_evict_lock, callb_generic_cpr, FTAG);
592
593 mutex_enter(&dbuf_evict_lock);
594 while (!dbuf_evict_thread_exit) {
595 while (!dbuf_cache_above_lowater() && !dbuf_evict_thread_exit) {
596 CALLB_CPR_SAFE_BEGIN(&cpr);
597 (void) cv_timedwait_hires(&dbuf_evict_cv,
598 &dbuf_evict_lock, SEC2NSEC(1), MSEC2NSEC(1), 0);
599 CALLB_CPR_SAFE_END(&cpr, &dbuf_evict_lock);
600 }
601 mutex_exit(&dbuf_evict_lock);
602
603 /*
604 * Keep evicting as long as we're above the low water mark
605 * for the cache. We do this without holding the locks to
606 * minimize lock contention.
607 */
608 while (dbuf_cache_above_lowater() && !dbuf_evict_thread_exit) {
609 dbuf_evict_one();
610 }
611
612 mutex_enter(&dbuf_evict_lock);
613 }
614
615 dbuf_evict_thread_exit = B_FALSE;
616 cv_broadcast(&dbuf_evict_cv);
617 CALLB_CPR_EXIT(&cpr); /* drops dbuf_evict_lock */
618 thread_exit();
619 }
620
621 /*
622 * Wake up the dbuf eviction thread if the dbuf cache is at its max size.
623 *
624 * Direct eviction (dbuf_evict_one()) is not called here, because
625 * the function doesn't care about the selected dbuf, so the following
626 * case is possible which will cause a deadlock-panic:
627 *
628 * Thread A is evicting dbufs that are related to dnodeA
629 * dnode_evict_dbufs(dnoneA) enters dn_dbufs_mtx and after that walks
630 * its own AVL of dbufs and calls dbuf_destroy():
631 * dbuf_destroy() ->...-> dbuf_evict_notify() -> dbuf_evict_one() ->
632 * -> select a dbuf from cache -> dbuf_destroy() ->
633 * -> mutex_enter(dn_dbufs_mtx of dnoneB)
634 *
635 * Thread B is evicting dbufs that are related to dnodeB
636 * dnode_evict_dbufs(dnoneB) enters dn_dbufs_mtx and after that walks
637 * its own AVL of dbufs and calls dbuf_destroy():
638 * dbuf_destroy() ->...-> dbuf_evict_notify() -> dbuf_evict_one() ->
639 * -> select a dbuf from cache -> dbuf_destroy() ->
640 * -> mutex_enter(dn_dbufs_mtx of dnoneA)
641 */
642 static void
643 dbuf_evict_notify(void)
644 {
645
646 /*
647 * We use thread specific data to track when a thread has
648 * started processing evictions. This allows us to avoid deeply
649 * nested stacks that would have a call flow similar to this:
650 *
651 * dbuf_rele()-->dbuf_rele_and_unlock()-->dbuf_evict_notify()
652 * ^ |
653 * | |
654 * +-----dbuf_destroy()<--dbuf_evict_one()<--------+
655 *
656 * The dbuf_eviction_thread will always have its tsd set until
657 * that thread exits. All other threads will only set their tsd
658 * if they are participating in the eviction process. This only
659 * happens if the eviction thread is unable to process evictions
660 * fast enough. To keep the dbuf cache size in check, other threads
661 * can evict from the dbuf cache directly. Those threads will set
662 * their tsd values so that we ensure that they only evict one dbuf
663 * from the dbuf cache.
664 */
665 if (tsd_get(zfs_dbuf_evict_key) != NULL)
666 return;
667
668 /*
669 * We check if we should evict without holding the dbuf_evict_lock,
670 * because it's OK to occasionally make the wrong decision here,
671 * and grabbing the lock results in massive lock contention.
672 */
673 if (refcount_count(&dbuf_caches[DB_DBUF_CACHE].size) >
674 dbuf_cache_max_bytes) {
675 if (dbuf_cache_above_hiwater())
676 dbuf_evict_one();
677 cv_signal(&dbuf_evict_cv);
678 }
679 }
680
681 void
682 dbuf_init(void)
683 {
684 uint64_t hsize = 1ULL << 16;
685 dbuf_hash_table_t *h = &dbuf_hash_table;
686 int i;
687
688 /*
689 * The hash table is big enough to fill all of physical memory
690 * with an average 4K block size. The table will take up
691 * totalmem*sizeof(void*)/4K (i.e. 2MB/GB with 8-byte pointers).
692 */
693 while (hsize * 4096 < physmem * PAGESIZE)
694 hsize <<= 1;
695
696 retry:
697 h->hash_table_mask = hsize - 1;
698 h->hash_table = kmem_zalloc(hsize * sizeof (void *), KM_NOSLEEP);
699 if (h->hash_table == NULL) {
700 /* XXX - we should really return an error instead of assert */
701 ASSERT(hsize > (1ULL << 10));
702 hsize >>= 1;
703 goto retry;
704 }
705
706 dbuf_kmem_cache = kmem_cache_create("dmu_buf_impl_t",
707 sizeof (dmu_buf_impl_t),
708 0, dbuf_cons, dbuf_dest, NULL, NULL, NULL, 0);
709
710 for (i = 0; i < DBUF_MUTEXES; i++)
711 mutex_init(DBUF_HASH_MUTEX(h, i), NULL, MUTEX_DEFAULT, NULL);
712
713
714 /*
715 * Setup the parameters for the dbuf caches. We set the sizes of the
716 * dbuf cache and the metadata cache to 1/32nd and 1/16th (default)
717 * of the size of the ARC, respectively.
718 */
719 if (dbuf_cache_max_bytes == 0 ||
720 dbuf_cache_max_bytes >= arc_max_bytes()) {
721 dbuf_cache_max_bytes = arc_max_bytes() >> dbuf_cache_shift;
722 }
723 if (dbuf_metadata_cache_max_bytes == 0 ||
724 dbuf_metadata_cache_max_bytes >= arc_max_bytes()) {
725 dbuf_metadata_cache_max_bytes =
726 arc_max_bytes() >> dbuf_metadata_cache_shift;
727 }
728
729 /*
730 * The combined size of both caches should be less
731 * the size of ARC, otherwise need to set them to
732 * the default values.
733 *
734 * divide by 2 is a simple overflow protection
735 */
736 if (((dbuf_cache_max_bytes / 2) +
737 (dbuf_metadata_cache_max_bytes / 2)) >= (arc_max_bytes() / 2)) {
738 dbuf_cache_max_bytes = arc_max_bytes() >> dbuf_cache_shift;
739 dbuf_metadata_cache_max_bytes =
740 arc_max_bytes() >> dbuf_metadata_cache_shift;
741 }
742
743
744 /*
745 * All entries are queued via taskq_dispatch_ent(), so min/maxalloc
746 * configuration is not required.
747 */
748 dbu_evict_taskq = taskq_create("dbu_evict", 1, minclsyspri, 0, 0, 0);
749
750 for (dbuf_cached_state_t dcs = 0; dcs < DB_CACHE_MAX; dcs++) {
751 dbuf_caches[dcs].cache =
752 multilist_create(sizeof (dmu_buf_impl_t),
753 offsetof(dmu_buf_impl_t, db_cache_link),
754 dbuf_cache_multilist_index_func);
755 refcount_create(&dbuf_caches[dcs].size);
756 }
757
758 tsd_create(&zfs_dbuf_evict_key, NULL);
759 dbuf_evict_thread_exit = B_FALSE;
760 mutex_init(&dbuf_evict_lock, NULL, MUTEX_DEFAULT, NULL);
761 cv_init(&dbuf_evict_cv, NULL, CV_DEFAULT, NULL);
762 dbuf_cache_evict_thread = thread_create(NULL, 0, dbuf_evict_thread,
763 NULL, 0, &p0, TS_RUN, minclsyspri);
764 }
765
766 void
767 dbuf_fini(void)
768 {
769 dbuf_hash_table_t *h = &dbuf_hash_table;
770 int i;
771
772 for (i = 0; i < DBUF_MUTEXES; i++)
773 mutex_destroy(DBUF_HASH_MUTEX(h, i));
774 kmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *));
775 kmem_cache_destroy(dbuf_kmem_cache);
776 taskq_destroy(dbu_evict_taskq);
777
778 mutex_enter(&dbuf_evict_lock);
779 dbuf_evict_thread_exit = B_TRUE;
780 while (dbuf_evict_thread_exit) {
781 cv_signal(&dbuf_evict_cv);
782 cv_wait(&dbuf_evict_cv, &dbuf_evict_lock);
783 }
784 mutex_exit(&dbuf_evict_lock);
785 tsd_destroy(&zfs_dbuf_evict_key);
786
787 mutex_destroy(&dbuf_evict_lock);
788 cv_destroy(&dbuf_evict_cv);
789
790 for (dbuf_cached_state_t dcs = 0; dcs < DB_CACHE_MAX; dcs++) {
791 refcount_destroy(&dbuf_caches[dcs].size);
792 multilist_destroy(dbuf_caches[dcs].cache);
793 }
794 }
795
796 /*
797 * Other stuff.
798 */
799
800 #ifdef ZFS_DEBUG
801 static void
802 dbuf_verify(dmu_buf_impl_t *db)
803 {
804 dnode_t *dn;
805 dbuf_dirty_record_t *dr;
806
807 ASSERT(MUTEX_HELD(&db->db_mtx));
808
809 if (!(zfs_flags & ZFS_DEBUG_DBUF_VERIFY))
810 return;
811
812 ASSERT(db->db_objset != NULL);
813 DB_DNODE_ENTER(db);
814 dn = DB_DNODE(db);
815 if (dn == NULL) {
816 ASSERT(db->db_parent == NULL);
817 ASSERT(db->db_blkptr == NULL);
818 } else {
819 ASSERT3U(db->db.db_object, ==, dn->dn_object);
820 ASSERT3P(db->db_objset, ==, dn->dn_objset);
821 ASSERT3U(db->db_level, <, dn->dn_nlevels);
822 ASSERT(db->db_blkid == DMU_BONUS_BLKID ||
823 db->db_blkid == DMU_SPILL_BLKID ||
824 !avl_is_empty(&dn->dn_dbufs));
825 }
826 if (db->db_blkid == DMU_BONUS_BLKID) {
827 ASSERT(dn != NULL);
828 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
829 ASSERT3U(db->db.db_offset, ==, DMU_BONUS_BLKID);
830 } else if (db->db_blkid == DMU_SPILL_BLKID) {
831 ASSERT(dn != NULL);
832 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
833 ASSERT0(db->db.db_offset);
834 } else {
835 ASSERT3U(db->db.db_offset, ==, db->db_blkid * db->db.db_size);
836 }
837
838 for (dr = db->db_data_pending; dr != NULL; dr = dr->dr_next)
839 ASSERT(dr->dr_dbuf == db);
840
841 for (dr = db->db_last_dirty; dr != NULL; dr = dr->dr_next)
842 ASSERT(dr->dr_dbuf == db);
843
844 /*
845 * We can't assert that db_size matches dn_datablksz because it
846 * can be momentarily different when another thread is doing
847 * dnode_set_blksz().
848 */
849 if (db->db_level == 0 && db->db.db_object == DMU_META_DNODE_OBJECT) {
850 dr = db->db_data_pending;
851 /*
852 * It should only be modified in syncing context, so
853 * make sure we only have one copy of the data.
854 */
855 ASSERT(dr == NULL || dr->dt.dl.dr_data == db->db_buf);
856 }
857
858 /* verify db->db_blkptr */
859 if (db->db_blkptr) {
860 if (db->db_parent == dn->dn_dbuf) {
861 /* db is pointed to by the dnode */
862 /* ASSERT3U(db->db_blkid, <, dn->dn_nblkptr); */
863 if (DMU_OBJECT_IS_SPECIAL(db->db.db_object))
864 ASSERT(db->db_parent == NULL);
865 else
866 ASSERT(db->db_parent != NULL);
867 if (db->db_blkid != DMU_SPILL_BLKID)
868 ASSERT3P(db->db_blkptr, ==,
869 &dn->dn_phys->dn_blkptr[db->db_blkid]);
870 } else {
871 /* db is pointed to by an indirect block */
872 int epb = db->db_parent->db.db_size >> SPA_BLKPTRSHIFT;
873 ASSERT3U(db->db_parent->db_level, ==, db->db_level+1);
874 ASSERT3U(db->db_parent->db.db_object, ==,
875 db->db.db_object);
876 /*
877 * dnode_grow_indblksz() can make this fail if we don't
878 * have the struct_rwlock. XXX indblksz no longer
879 * grows. safe to do this now?
880 */
881 if (RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
882 ASSERT3P(db->db_blkptr, ==,
883 ((blkptr_t *)db->db_parent->db.db_data +
884 db->db_blkid % epb));
885 }
886 }
887 }
888 if ((db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr)) &&
889 (db->db_buf == NULL || db->db_buf->b_data) &&
890 db->db.db_data && db->db_blkid != DMU_BONUS_BLKID &&
891 db->db_state != DB_FILL && !dn->dn_free_txg) {
892 /*
893 * If the blkptr isn't set but they have nonzero data,
894 * it had better be dirty, otherwise we'll lose that
895 * data when we evict this buffer.
896 *
897 * There is an exception to this rule for indirect blocks; in
898 * this case, if the indirect block is a hole, we fill in a few
899 * fields on each of the child blocks (importantly, birth time)
900 * to prevent hole birth times from being lost when you
901 * partially fill in a hole.
902 */
903 if (db->db_dirtycnt == 0) {
904 if (db->db_level == 0) {
905 uint64_t *buf = db->db.db_data;
906 int i;
907
908 for (i = 0; i < db->db.db_size >> 3; i++) {
909 ASSERT(buf[i] == 0);
910 }
911 } else {
912 blkptr_t *bps = db->db.db_data;
913 ASSERT3U(1 << DB_DNODE(db)->dn_indblkshift, ==,
914 db->db.db_size);
915 /*
916 * We want to verify that all the blkptrs in the
917 * indirect block are holes, but we may have
918 * automatically set up a few fields for them.
919 * We iterate through each blkptr and verify
920 * they only have those fields set.
921 */
922 for (int i = 0;
923 i < db->db.db_size / sizeof (blkptr_t);
924 i++) {
925 blkptr_t *bp = &bps[i];
926 ASSERT(ZIO_CHECKSUM_IS_ZERO(
927 &bp->blk_cksum));
928 ASSERT(
929 DVA_IS_EMPTY(&bp->blk_dva[0]) &&
930 DVA_IS_EMPTY(&bp->blk_dva[1]) &&
931 DVA_IS_EMPTY(&bp->blk_dva[2]));
932 ASSERT0(bp->blk_fill);
933 ASSERT0(bp->blk_pad[0]);
934 ASSERT0(bp->blk_pad[1]);
935 ASSERT(!BP_IS_EMBEDDED(bp));
936 ASSERT(BP_IS_HOLE(bp));
937 ASSERT0(bp->blk_phys_birth);
938 }
939 }
940 }
941 }
942 DB_DNODE_EXIT(db);
943 }
944 #endif
945
946 static void
947 dbuf_clear_data(dmu_buf_impl_t *db)
948 {
949 ASSERT(MUTEX_HELD(&db->db_mtx));
950 dbuf_evict_user(db);
951 ASSERT3P(db->db_buf, ==, NULL);
952 db->db.db_data = NULL;
953 if (db->db_state != DB_NOFILL)
954 db->db_state = DB_UNCACHED;
955 }
956
957 static void
958 dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf)
959 {
960 ASSERT(MUTEX_HELD(&db->db_mtx));
961 ASSERT(buf != NULL);
962
963 db->db_buf = buf;
964 ASSERT(buf->b_data != NULL);
965 db->db.db_data = buf->b_data;
966 }
967
968 /*
969 * Loan out an arc_buf for read. Return the loaned arc_buf.
970 */
971 arc_buf_t *
972 dbuf_loan_arcbuf(dmu_buf_impl_t *db)
973 {
974 arc_buf_t *abuf;
975
976 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
977 mutex_enter(&db->db_mtx);
978 if (arc_released(db->db_buf) || refcount_count(&db->db_holds) > 1) {
979 int blksz = db->db.db_size;
980 spa_t *spa = db->db_objset->os_spa;
981
982 mutex_exit(&db->db_mtx);
983 abuf = arc_loan_buf(spa, B_FALSE, blksz);
984 bcopy(db->db.db_data, abuf->b_data, blksz);
985 } else {
986 abuf = db->db_buf;
987 arc_loan_inuse_buf(abuf, db);
988 db->db_buf = NULL;
989 dbuf_clear_data(db);
990 mutex_exit(&db->db_mtx);
991 }
992 return (abuf);
993 }
994
995 /*
996 * Calculate which level n block references the data at the level 0 offset
997 * provided.
998 */
999 uint64_t
1000 dbuf_whichblock(dnode_t *dn, int64_t level, uint64_t offset)
1001 {
1002 if (dn->dn_datablkshift != 0 && dn->dn_indblkshift != 0) {
1003 /*
1004 * The level n blkid is equal to the level 0 blkid divided by
1005 * the number of level 0s in a level n block.
1006 *
1007 * The level 0 blkid is offset >> datablkshift =
1008 * offset / 2^datablkshift.
1009 *
1010 * The number of level 0s in a level n is the number of block
1011 * pointers in an indirect block, raised to the power of level.
1012 * This is 2^(indblkshift - SPA_BLKPTRSHIFT)^level =
1013 * 2^(level*(indblkshift - SPA_BLKPTRSHIFT)).
1014 *
1015 * Thus, the level n blkid is: offset /
1016 * ((2^datablkshift)*(2^(level*(indblkshift - SPA_BLKPTRSHIFT)))
1017 * = offset / 2^(datablkshift + level *
1018 * (indblkshift - SPA_BLKPTRSHIFT))
1019 * = offset >> (datablkshift + level *
1020 * (indblkshift - SPA_BLKPTRSHIFT))
1021 */
1022 return (offset >> (dn->dn_datablkshift + level *
1023 (dn->dn_indblkshift - SPA_BLKPTRSHIFT)));
1024 } else {
1025 ASSERT3U(offset, <, dn->dn_datablksz);
1026 return (0);
1027 }
1028 }
1029
1030 static void
1031 dbuf_read_done(zio_t *zio, arc_buf_t *buf, void *vdb)
1032 {
1033 dmu_buf_impl_t *db = vdb;
1034
1035 mutex_enter(&db->db_mtx);
1036 ASSERT3U(db->db_state, ==, DB_READ);
1037 /*
1038 * All reads are synchronous, so we must have a hold on the dbuf
1039 */
1040 ASSERT(refcount_count(&db->db_holds) > 0);
1041 ASSERT(db->db_buf == NULL);
1042 ASSERT(db->db.db_data == NULL);
1043 if (db->db_level == 0 && db->db_freed_in_flight) {
1044 /* we were freed in flight; disregard any error */
1045 arc_release(buf, db);
1046 bzero(buf->b_data, db->db.db_size);
1047 arc_buf_freeze(buf);
1048 db->db_freed_in_flight = FALSE;
1049 dbuf_set_data(db, buf);
1050 db->db_state = DB_CACHED;
1051 } else if (zio == NULL || zio->io_error == 0) {
1052 dbuf_set_data(db, buf);
1053 db->db_state = DB_CACHED;
1054 } else {
1055 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1056 ASSERT3P(db->db_buf, ==, NULL);
1057 arc_buf_destroy(buf, db);
1058 db->db_state = DB_UNCACHED;
1059 }
1060 cv_broadcast(&db->db_changed);
1061 dbuf_rele_and_unlock(db, NULL);
1062 }
1063
1064 static void
1065 dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
1066 {
1067 dnode_t *dn;
1068 zbookmark_phys_t zb;
1069 arc_flags_t aflags = ARC_FLAG_NOWAIT;
1070
1071 DB_DNODE_ENTER(db);
1072 dn = DB_DNODE(db);
1073 ASSERT(!refcount_is_zero(&db->db_holds));
1074 /* We need the struct_rwlock to prevent db_blkptr from changing. */
1075 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1076 ASSERT(MUTEX_HELD(&db->db_mtx));
1077 ASSERT(db->db_state == DB_UNCACHED);
1078 ASSERT(db->db_buf == NULL);
1079
1080 if (db->db_blkid == DMU_BONUS_BLKID) {
1081 int bonuslen = MIN(dn->dn_bonuslen, dn->dn_phys->dn_bonuslen);
1082
1083 ASSERT3U(bonuslen, <=, db->db.db_size);
1084 db->db.db_data = zio_buf_alloc(DN_MAX_BONUSLEN);
1085 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
1086 if (bonuslen < DN_MAX_BONUSLEN)
1087 bzero(db->db.db_data, DN_MAX_BONUSLEN);
1088 if (bonuslen)
1089 bcopy(DN_BONUS(dn->dn_phys), db->db.db_data, bonuslen);
1090 DB_DNODE_EXIT(db);
1091 db->db_state = DB_CACHED;
1092 mutex_exit(&db->db_mtx);
1093 return;
1094 }
1095
1096 /*
1097 * Recheck BP_IS_HOLE() after dnode_block_freed() in case dnode_sync()
1098 * processes the delete record and clears the bp while we are waiting
1099 * for the dn_mtx (resulting in a "no" from block_freed).
1100 */
1101 if (db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr) ||
1102 (db->db_level == 0 && (dnode_block_freed(dn, db->db_blkid) ||
1103 BP_IS_HOLE(db->db_blkptr)))) {
1104 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
1105
1106 dbuf_set_data(db, arc_alloc_buf(db->db_objset->os_spa, db, type,
1107 db->db.db_size));
1108 bzero(db->db.db_data, db->db.db_size);
1109
1110 if (db->db_blkptr != NULL && db->db_level > 0 &&
1111 BP_IS_HOLE(db->db_blkptr) &&
1112 db->db_blkptr->blk_birth != 0) {
1113 blkptr_t *bps = db->db.db_data;
1114 for (int i = 0; i < ((1 <<
1115 DB_DNODE(db)->dn_indblkshift) / sizeof (blkptr_t));
1116 i++) {
1117 blkptr_t *bp = &bps[i];
1118 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==,
1119 1 << dn->dn_indblkshift);
1120 BP_SET_LSIZE(bp,
1121 BP_GET_LEVEL(db->db_blkptr) == 1 ?
1122 dn->dn_datablksz :
1123 BP_GET_LSIZE(db->db_blkptr));
1124 BP_SET_TYPE(bp, BP_GET_TYPE(db->db_blkptr));
1125 BP_SET_LEVEL(bp,
1126 BP_GET_LEVEL(db->db_blkptr) - 1);
1127 BP_SET_BIRTH(bp, db->db_blkptr->blk_birth, 0);
1128 }
1129 }
1130 DB_DNODE_EXIT(db);
1131 db->db_state = DB_CACHED;
1132 mutex_exit(&db->db_mtx);
1133 return;
1134 }
1135
1136 DB_DNODE_EXIT(db);
1137
1138 db->db_state = DB_READ;
1139 mutex_exit(&db->db_mtx);
1140
1141 if (DBUF_IS_L2CACHEABLE(db))
1142 aflags |= ARC_FLAG_L2CACHE;
1143
1144 SET_BOOKMARK(&zb, db->db_objset->os_dsl_dataset ?
1145 db->db_objset->os_dsl_dataset->ds_object : DMU_META_OBJSET,
1146 db->db.db_object, db->db_level, db->db_blkid);
1147
1148 dbuf_add_ref(db, NULL);
1149
1150 (void) arc_read(zio, db->db_objset->os_spa, db->db_blkptr,
1151 dbuf_read_done, db, ZIO_PRIORITY_SYNC_READ,
1152 (flags & DB_RF_CANFAIL) ? ZIO_FLAG_CANFAIL : ZIO_FLAG_MUSTSUCCEED,
1153 &aflags, &zb);
1154 }
1155
1156 /*
1157 * This is our just-in-time copy function. It makes a copy of buffers that
1158 * have been modified in a previous transaction group before we access them in
1159 * the current active group.
1160 *
1161 * This function is used in three places: when we are dirtying a buffer for the
1162 * first time in a txg, when we are freeing a range in a dnode that includes
1163 * this buffer, and when we are accessing a buffer which was received compressed
1164 * and later referenced in a WRITE_BYREF record.
1165 *
1166 * Note that when we are called from dbuf_free_range() we do not put a hold on
1167 * the buffer, we just traverse the active dbuf list for the dnode.
1168 */
1169 static void
1170 dbuf_fix_old_data(dmu_buf_impl_t *db, uint64_t txg)
1171 {
1172 dbuf_dirty_record_t *dr = db->db_last_dirty;
1173
1174 ASSERT(MUTEX_HELD(&db->db_mtx));
1175 ASSERT(db->db.db_data != NULL);
1176 ASSERT(db->db_level == 0);
1177 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT);
1178
1179 if (dr == NULL ||
1180 (dr->dt.dl.dr_data !=
1181 ((db->db_blkid == DMU_BONUS_BLKID) ? db->db.db_data : db->db_buf)))
1182 return;
1183
1184 /*
1185 * If the last dirty record for this dbuf has not yet synced
1186 * and its referencing the dbuf data, either:
1187 * reset the reference to point to a new copy,
1188 * or (if there a no active holders)
1189 * just null out the current db_data pointer.
1190 */
1191 ASSERT(dr->dr_txg >= txg - 2);
1192 if (db->db_blkid == DMU_BONUS_BLKID) {
1193 /* Note that the data bufs here are zio_bufs */
1194 dr->dt.dl.dr_data = zio_buf_alloc(DN_MAX_BONUSLEN);
1195 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
1196 bcopy(db->db.db_data, dr->dt.dl.dr_data, DN_MAX_BONUSLEN);
1197 } else if (refcount_count(&db->db_holds) > db->db_dirtycnt) {
1198 int size = arc_buf_size(db->db_buf);
1199 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
1200 spa_t *spa = db->db_objset->os_spa;
1201 enum zio_compress compress_type =
1202 arc_get_compression(db->db_buf);
1203
1204 if (compress_type == ZIO_COMPRESS_OFF) {
1205 dr->dt.dl.dr_data = arc_alloc_buf(spa, db, type, size);
1206 } else {
1207 ASSERT3U(type, ==, ARC_BUFC_DATA);
1208 dr->dt.dl.dr_data = arc_alloc_compressed_buf(spa, db,
1209 size, arc_buf_lsize(db->db_buf), compress_type);
1210 }
1211 bcopy(db->db.db_data, dr->dt.dl.dr_data->b_data, size);
1212 } else {
1213 db->db_buf = NULL;
1214 dbuf_clear_data(db);
1215 }
1216 }
1217
1218 int
1219 dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
1220 {
1221 int err = 0;
1222 boolean_t prefetch;
1223 dnode_t *dn;
1224
1225 /*
1226 * We don't have to hold the mutex to check db_state because it
1227 * can't be freed while we have a hold on the buffer.
1228 */
1229 ASSERT(!refcount_is_zero(&db->db_holds));
1230
1231 if (db->db_state == DB_NOFILL)
1232 return (SET_ERROR(EIO));
1233
1234 DB_DNODE_ENTER(db);
1235 dn = DB_DNODE(db);
1236 if ((flags & DB_RF_HAVESTRUCT) == 0)
1237 rw_enter(&dn->dn_struct_rwlock, RW_READER);
1238
1239 prefetch = db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
1240 (flags & DB_RF_NOPREFETCH) == 0 && dn != NULL &&
1241 DBUF_IS_CACHEABLE(db);
1242
1243 mutex_enter(&db->db_mtx);
1244 if (db->db_state == DB_CACHED) {
1245 /*
1246 * If the arc buf is compressed, we need to decompress it to
1247 * read the data. This could happen during the "zfs receive" of
1248 * a stream which is compressed and deduplicated.
1249 */
1250 if (db->db_buf != NULL &&
1251 arc_get_compression(db->db_buf) != ZIO_COMPRESS_OFF) {
1252 dbuf_fix_old_data(db,
1253 spa_syncing_txg(dmu_objset_spa(db->db_objset)));
1254 err = arc_decompress(db->db_buf);
1255 dbuf_set_data(db, db->db_buf);
1256 }
1257 mutex_exit(&db->db_mtx);
1258 if (prefetch)
1259 dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1, B_TRUE);
1260 if ((flags & DB_RF_HAVESTRUCT) == 0)
1261 rw_exit(&dn->dn_struct_rwlock);
1262 DB_DNODE_EXIT(db);
1263 } else if (db->db_state == DB_UNCACHED) {
1264 spa_t *spa = dn->dn_objset->os_spa;
1265 boolean_t need_wait = B_FALSE;
1266
1267 if (zio == NULL &&
1268 db->db_blkptr != NULL && !BP_IS_HOLE(db->db_blkptr)) {
1269 zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL);
1270 need_wait = B_TRUE;
1271 }
1272 dbuf_read_impl(db, zio, flags);
1273
1274 /* dbuf_read_impl has dropped db_mtx for us */
1275
1276 if (prefetch)
1277 dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1, B_TRUE);
1278
1279 if ((flags & DB_RF_HAVESTRUCT) == 0)
1280 rw_exit(&dn->dn_struct_rwlock);
1281 DB_DNODE_EXIT(db);
1282
1283 if (need_wait)
1284 err = zio_wait(zio);
1285 } else {
1286 /*
1287 * Another reader came in while the dbuf was in flight
1288 * between UNCACHED and CACHED. Either a writer will finish
1289 * writing the buffer (sending the dbuf to CACHED) or the
1290 * first reader's request will reach the read_done callback
1291 * and send the dbuf to CACHED. Otherwise, a failure
1292 * occurred and the dbuf went to UNCACHED.
1293 */
1294 mutex_exit(&db->db_mtx);
1295 if (prefetch)
1296 dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1, B_TRUE);
1297 if ((flags & DB_RF_HAVESTRUCT) == 0)
1298 rw_exit(&dn->dn_struct_rwlock);
1299 DB_DNODE_EXIT(db);
1300
1301 /* Skip the wait per the caller's request. */
1302 mutex_enter(&db->db_mtx);
1303 if ((flags & DB_RF_NEVERWAIT) == 0) {
1304 while (db->db_state == DB_READ ||
1305 db->db_state == DB_FILL) {
1306 ASSERT(db->db_state == DB_READ ||
1307 (flags & DB_RF_HAVESTRUCT) == 0);
1308 DTRACE_PROBE2(blocked__read, dmu_buf_impl_t *,
1309 db, zio_t *, zio);
1310 cv_wait(&db->db_changed, &db->db_mtx);
1311 }
1312 if (db->db_state == DB_UNCACHED)
1313 err = SET_ERROR(EIO);
1314 }
1315 mutex_exit(&db->db_mtx);
1316 }
1317
1318 return (err);
1319 }
1320
1321 static void
1322 dbuf_noread(dmu_buf_impl_t *db)
1323 {
1324 ASSERT(!refcount_is_zero(&db->db_holds));
1325 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1326 mutex_enter(&db->db_mtx);
1327 while (db->db_state == DB_READ || db->db_state == DB_FILL)
1328 cv_wait(&db->db_changed, &db->db_mtx);
1329 if (db->db_state == DB_UNCACHED) {
1330 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
1331 spa_t *spa = db->db_objset->os_spa;
1332
1333 ASSERT(db->db_buf == NULL);
1334 ASSERT(db->db.db_data == NULL);
1335 dbuf_set_data(db, arc_alloc_buf(spa, db, type, db->db.db_size));
1336 db->db_state = DB_FILL;
1337 } else if (db->db_state == DB_NOFILL) {
1338 dbuf_clear_data(db);
1339 } else {
1340 ASSERT3U(db->db_state, ==, DB_CACHED);
1341 }
1342 mutex_exit(&db->db_mtx);
1343 }
1344
1345 void
1346 dbuf_unoverride(dbuf_dirty_record_t *dr)
1347 {
1348 dmu_buf_impl_t *db = dr->dr_dbuf;
1349 blkptr_t *bp = &dr->dt.dl.dr_overridden_by;
1350 uint64_t txg = dr->dr_txg;
1351
1352 ASSERT(MUTEX_HELD(&db->db_mtx));
1353 /*
1354 * This assert is valid because dmu_sync() expects to be called by
1355 * a zilog's get_data while holding a range lock. This call only
1356 * comes from dbuf_dirty() callers who must also hold a range lock.
1357 */
1358 ASSERT(dr->dt.dl.dr_override_state != DR_IN_DMU_SYNC);
1359 ASSERT(db->db_level == 0);
1360
1361 if (db->db_blkid == DMU_BONUS_BLKID ||
1362 dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN)
1363 return;
1364
1365 ASSERT(db->db_data_pending != dr);
1366
1367 /* free this block */
1368 if (!BP_IS_HOLE(bp) && !dr->dt.dl.dr_nopwrite)
1369 zio_free(db->db_objset->os_spa, txg, bp);
1370
1371 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
1372 dr->dt.dl.dr_nopwrite = B_FALSE;
1373
1374 /*
1375 * Release the already-written buffer, so we leave it in
1376 * a consistent dirty state. Note that all callers are
1377 * modifying the buffer, so they will immediately do
1378 * another (redundant) arc_release(). Therefore, leave
1379 * the buf thawed to save the effort of freezing &
1380 * immediately re-thawing it.
1381 */
1382 arc_release(dr->dt.dl.dr_data, db);
1383 }
1384
1385 /*
1386 * Evict (if its unreferenced) or clear (if its referenced) any level-0
1387 * data blocks in the free range, so that any future readers will find
1388 * empty blocks.
1389 */
1390 void
1391 dbuf_free_range(dnode_t *dn, uint64_t start_blkid, uint64_t end_blkid,
1392 dmu_tx_t *tx)
1393 {
1394 dmu_buf_impl_t db_search;
1395 dmu_buf_impl_t *db, *db_next;
1396 uint64_t txg = tx->tx_txg;
1397 avl_index_t where;
1398
1399 if (end_blkid > dn->dn_maxblkid &&
1400 !(start_blkid == DMU_SPILL_BLKID || end_blkid == DMU_SPILL_BLKID))
1401 end_blkid = dn->dn_maxblkid;
1402 dprintf_dnode(dn, "start=%llu end=%llu\n", start_blkid, end_blkid);
1403
1404 db_search.db_level = 0;
1405 db_search.db_blkid = start_blkid;
1406 db_search.db_state = DB_SEARCH;
1407
1408 mutex_enter(&dn->dn_dbufs_mtx);
1409 db = avl_find(&dn->dn_dbufs, &db_search, &where);
1410 ASSERT3P(db, ==, NULL);
1411
1412 db = avl_nearest(&dn->dn_dbufs, where, AVL_AFTER);
1413
1414 for (; db != NULL; db = db_next) {
1415 db_next = AVL_NEXT(&dn->dn_dbufs, db);
1416 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1417
1418 if (db->db_level != 0 || db->db_blkid > end_blkid) {
1419 break;
1420 }
1421 ASSERT3U(db->db_blkid, >=, start_blkid);
1422
1423 /* found a level 0 buffer in the range */
1424 mutex_enter(&db->db_mtx);
1425 if (dbuf_undirty(db, tx)) {
1426 /* mutex has been dropped and dbuf destroyed */
1427 continue;
1428 }
1429
1430 if (db->db_state == DB_UNCACHED ||
1431 db->db_state == DB_NOFILL ||
1432 db->db_state == DB_EVICTING) {
1433 ASSERT(db->db.db_data == NULL);
1434 mutex_exit(&db->db_mtx);
1435 continue;
1436 }
1437 if (db->db_state == DB_READ || db->db_state == DB_FILL) {
1438 /* will be handled in dbuf_read_done or dbuf_rele */
1439 db->db_freed_in_flight = TRUE;
1440 mutex_exit(&db->db_mtx);
1441 continue;
1442 }
1443 if (refcount_count(&db->db_holds) == 0) {
1444 ASSERT(db->db_buf);
1445 dbuf_destroy(db);
1446 continue;
1447 }
1448 /* The dbuf is referenced */
1449
1450 if (db->db_last_dirty != NULL) {
1451 dbuf_dirty_record_t *dr = db->db_last_dirty;
1452
1453 if (dr->dr_txg == txg) {
1454 /*
1455 * This buffer is "in-use", re-adjust the file
1456 * size to reflect that this buffer may
1457 * contain new data when we sync.
1458 */
1459 if (db->db_blkid != DMU_SPILL_BLKID &&
1460 db->db_blkid > dn->dn_maxblkid)
1461 dn->dn_maxblkid = db->db_blkid;
1462 dbuf_unoverride(dr);
1463 } else {
1464 /*
1465 * This dbuf is not dirty in the open context.
1466 * Either uncache it (if its not referenced in
1467 * the open context) or reset its contents to
1468 * empty.
1469 */
1470 dbuf_fix_old_data(db, txg);
1471 }
1472 }
1473 /* clear the contents if its cached */
1474 if (db->db_state == DB_CACHED) {
1475 ASSERT(db->db.db_data != NULL);
1476 arc_release(db->db_buf, db);
1477 bzero(db->db.db_data, db->db.db_size);
1478 arc_buf_freeze(db->db_buf);
1479 }
1480
1481 mutex_exit(&db->db_mtx);
1482 }
1483 mutex_exit(&dn->dn_dbufs_mtx);
1484 }
1485
1486 void
1487 dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx)
1488 {
1489 arc_buf_t *buf, *obuf;
1490 int osize = db->db.db_size;
1491 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
1492 dnode_t *dn;
1493
1494 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1495
1496 DB_DNODE_ENTER(db);
1497 dn = DB_DNODE(db);
1498
1499 /* XXX does *this* func really need the lock? */
1500 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
1501
1502 /*
1503 * This call to dmu_buf_will_dirty() with the dn_struct_rwlock held
1504 * is OK, because there can be no other references to the db
1505 * when we are changing its size, so no concurrent DB_FILL can
1506 * be happening.
1507 */
1508 /*
1509 * XXX we should be doing a dbuf_read, checking the return
1510 * value and returning that up to our callers
1511 */
1512 dmu_buf_will_dirty(&db->db, tx);
1513
1514 /* create the data buffer for the new block */
1515 buf = arc_alloc_buf(dn->dn_objset->os_spa, db, type, size);
1516
1517 /* copy old block data to the new block */
1518 obuf = db->db_buf;
1519 bcopy(obuf->b_data, buf->b_data, MIN(osize, size));
1520 /* zero the remainder */
1521 if (size > osize)
1522 bzero((uint8_t *)buf->b_data + osize, size - osize);
1523
1524 mutex_enter(&db->db_mtx);
1525 dbuf_set_data(db, buf);
1526 arc_buf_destroy(obuf, db);
1527 db->db.db_size = size;
1528
1529 if (db->db_level == 0) {
1530 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
1531 db->db_last_dirty->dt.dl.dr_data = buf;
1532 }
1533 mutex_exit(&db->db_mtx);
1534
1535 dmu_objset_willuse_space(dn->dn_objset, size - osize, tx);
1536 DB_DNODE_EXIT(db);
1537 }
1538
1539 void
1540 dbuf_release_bp(dmu_buf_impl_t *db)
1541 {
1542 objset_t *os = db->db_objset;
1543
1544 ASSERT(dsl_pool_sync_context(dmu_objset_pool(os)));
1545 ASSERT(arc_released(os->os_phys_buf) ||
1546 list_link_active(&os->os_dsl_dataset->ds_synced_link));
1547 ASSERT(db->db_parent == NULL || arc_released(db->db_parent->db_buf));
1548
1549 (void) arc_release(db->db_buf, db);
1550 }
1551
1552 /*
1553 * We already have a dirty record for this TXG, and we are being
1554 * dirtied again.
1555 */
1556 static void
1557 dbuf_redirty(dbuf_dirty_record_t *dr, boolean_t usesc)
1558 {
1559 dmu_buf_impl_t *db = dr->dr_dbuf;
1560
1561 ASSERT(MUTEX_HELD(&db->db_mtx));
1562
1563 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID) {
1564 /*
1565 * If this buffer has already been written out,
1566 * we now need to reset its state.
1567 */
1568 dbuf_unoverride(dr);
1569 if (db->db.db_object != DMU_META_DNODE_OBJECT &&
1570 db->db_state != DB_NOFILL) {
1571 /* Already released on initial dirty, so just thaw. */
1572 ASSERT(arc_released(db->db_buf));
1573 arc_buf_thaw(db->db_buf);
1574 }
1575 }
1576 /*
1577 * Special class usage of dirty dbuf could be changed,
1578 * update the dirty entry.
1579 */
1580 dr->dr_usesc = usesc;
1581 }
1582
1583 dbuf_dirty_record_t *
1584 dbuf_dirty_sc(dmu_buf_impl_t *db, dmu_tx_t *tx, boolean_t usesc)
1585 {
1586 dnode_t *dn;
1587 objset_t *os;
1588 dbuf_dirty_record_t **drp, *dr;
1589 int drop_struct_lock = FALSE;
1590 int txgoff = tx->tx_txg & TXG_MASK;
1591
1592 ASSERT(tx->tx_txg != 0);
1593 ASSERT(!refcount_is_zero(&db->db_holds));
1594 DMU_TX_DIRTY_BUF(tx, db);
1595
1596 DB_DNODE_ENTER(db);
1597 dn = DB_DNODE(db);
1598 /*
1599 * Shouldn't dirty a regular buffer in syncing context. Private
1600 * objects may be dirtied in syncing context, but only if they
1601 * were already pre-dirtied in open context.
1602 */
1603 #ifdef DEBUG
1604 if (dn->dn_objset->os_dsl_dataset != NULL) {
1605 rrw_enter(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock,
1606 RW_READER, FTAG);
1607 }
1608 ASSERT(!dmu_tx_is_syncing(tx) ||
1609 BP_IS_HOLE(dn->dn_objset->os_rootbp) ||
1610 DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1611 dn->dn_objset->os_dsl_dataset == NULL);
1612 if (dn->dn_objset->os_dsl_dataset != NULL)
1613 rrw_exit(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock, FTAG);
1614 #endif
1615 /*
1616 * We make this assert for private objects as well, but after we
1617 * check if we're already dirty. They are allowed to re-dirty
1618 * in syncing context.
1619 */
1620 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1621 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1622 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1623
1624 mutex_enter(&db->db_mtx);
1625 /*
1626 * XXX make this true for indirects too? The problem is that
1627 * transactions created with dmu_tx_create_assigned() from
1628 * syncing context don't bother holding ahead.
1629 */
1630 ASSERT(db->db_level != 0 ||
1631 db->db_state == DB_CACHED || db->db_state == DB_FILL ||
1632 db->db_state == DB_NOFILL);
1633
1634 mutex_enter(&dn->dn_mtx);
1635 /*
1636 * Don't set dirtyctx to SYNC if we're just modifying this as we
1637 * initialize the objset.
1638 */
1639 if (dn->dn_dirtyctx == DN_UNDIRTIED) {
1640 if (dn->dn_objset->os_dsl_dataset != NULL) {
1641 rrw_enter(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock,
1642 RW_READER, FTAG);
1643 }
1644 if (!BP_IS_HOLE(dn->dn_objset->os_rootbp)) {
1645 dn->dn_dirtyctx = (dmu_tx_is_syncing(tx) ?
1646 DN_DIRTY_SYNC : DN_DIRTY_OPEN);
1647 ASSERT(dn->dn_dirtyctx_firstset == NULL);
1648 dn->dn_dirtyctx_firstset = kmem_alloc(1, KM_SLEEP);
1649 }
1650 if (dn->dn_objset->os_dsl_dataset != NULL) {
1651 rrw_exit(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock,
1652 FTAG);
1653 }
1654 }
1655 mutex_exit(&dn->dn_mtx);
1656
1657 if (db->db_blkid == DMU_SPILL_BLKID)
1658 dn->dn_have_spill = B_TRUE;
1659
1660 /*
1661 * If this buffer is already dirty, we're done.
1662 */
1663 drp = &db->db_last_dirty;
1664 ASSERT(*drp == NULL || (*drp)->dr_txg <= tx->tx_txg ||
1665 db->db.db_object == DMU_META_DNODE_OBJECT);
1666 while ((dr = *drp) != NULL && dr->dr_txg > tx->tx_txg)
1667 drp = &dr->dr_next;
1668 if (dr && dr->dr_txg == tx->tx_txg) {
1669 DB_DNODE_EXIT(db);
1670
1671 dbuf_redirty(dr, usesc);
1672 mutex_exit(&db->db_mtx);
1673 return (dr);
1674 }
1675
1676 /*
1677 * Only valid if not already dirty.
1678 */
1679 ASSERT(dn->dn_object == 0 ||
1680 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1681 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1682
1683 ASSERT3U(dn->dn_nlevels, >, db->db_level);
1684
1685 /*
1686 * We should only be dirtying in syncing context if it's the
1687 * mos or we're initializing the os or it's a special object.
1688 * However, we are allowed to dirty in syncing context provided
1689 * we already dirtied it in open context. Hence we must make
1690 * this assertion only if we're not already dirty.
1691 */
1692 os = dn->dn_objset;
1693 VERIFY3U(tx->tx_txg, <=, spa_final_dirty_txg(os->os_spa));
1694 #ifdef DEBUG
1695 if (dn->dn_objset->os_dsl_dataset != NULL)
1696 rrw_enter(&os->os_dsl_dataset->ds_bp_rwlock, RW_READER, FTAG);
1697 ASSERT(!dmu_tx_is_syncing(tx) || DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1698 os->os_dsl_dataset == NULL || BP_IS_HOLE(os->os_rootbp));
1699 if (dn->dn_objset->os_dsl_dataset != NULL)
1700 rrw_exit(&os->os_dsl_dataset->ds_bp_rwlock, FTAG);
1701 #endif
1702 ASSERT(db->db.db_size != 0);
1703
1704 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1705
1706 if (db->db_blkid != DMU_BONUS_BLKID) {
1707 dmu_objset_willuse_space(os, db->db.db_size, tx);
1708 }
1709
1710 /*
1711 * If this buffer is dirty in an old transaction group we need
1712 * to make a copy of it so that the changes we make in this
1713 * transaction group won't leak out when we sync the older txg.
1714 */
1715 dr = kmem_zalloc(sizeof (dbuf_dirty_record_t), KM_SLEEP);
1716 if (db->db_level == 0) {
1717 void *data_old = db->db_buf;
1718
1719 if (db->db_state != DB_NOFILL) {
1720 if (db->db_blkid == DMU_BONUS_BLKID) {
1721 dbuf_fix_old_data(db, tx->tx_txg);
1722 data_old = db->db.db_data;
1723 } else if (db->db.db_object != DMU_META_DNODE_OBJECT) {
1724 /*
1725 * Release the data buffer from the cache so
1726 * that we can modify it without impacting
1727 * possible other users of this cached data
1728 * block. Note that indirect blocks and
1729 * private objects are not released until the
1730 * syncing state (since they are only modified
1731 * then).
1732 */
1733 arc_release(db->db_buf, db);
1734 dbuf_fix_old_data(db, tx->tx_txg);
1735 data_old = db->db_buf;
1736 }
1737 ASSERT(data_old != NULL);
1738 }
1739 dr->dt.dl.dr_data = data_old;
1740 } else {
1741 mutex_init(&dr->dt.di.dr_mtx, NULL, MUTEX_DEFAULT, NULL);
1742 list_create(&dr->dt.di.dr_children,
1743 sizeof (dbuf_dirty_record_t),
1744 offsetof(dbuf_dirty_record_t, dr_dirty_node));
1745 }
1746 if (db->db_blkid != DMU_BONUS_BLKID && os->os_dsl_dataset != NULL)
1747 dr->dr_accounted = db->db.db_size;
1748 dr->dr_dbuf = db;
1749 dr->dr_txg = tx->tx_txg;
1750 dr->dr_next = *drp;
1751 dr->dr_usesc = usesc;
1752 *drp = dr;
1753
1754 /*
1755 * We could have been freed_in_flight between the dbuf_noread
1756 * and dbuf_dirty. We win, as though the dbuf_noread() had
1757 * happened after the free.
1758 */
1759 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
1760 db->db_blkid != DMU_SPILL_BLKID) {
1761 mutex_enter(&dn->dn_mtx);
1762 if (dn->dn_free_ranges[txgoff] != NULL) {
1763 range_tree_clear(dn->dn_free_ranges[txgoff],
1764 db->db_blkid, 1);
1765 }
1766 mutex_exit(&dn->dn_mtx);
1767 db->db_freed_in_flight = FALSE;
1768 }
1769
1770 /*
1771 * This buffer is now part of this txg
1772 */
1773 dbuf_add_ref(db, (void *)(uintptr_t)tx->tx_txg);
1774 db->db_dirtycnt += 1;
1775 ASSERT3U(db->db_dirtycnt, <=, 3);
1776
1777 mutex_exit(&db->db_mtx);
1778
1779 if (db->db_blkid == DMU_BONUS_BLKID ||
1780 db->db_blkid == DMU_SPILL_BLKID) {
1781 mutex_enter(&dn->dn_mtx);
1782 ASSERT(!list_link_active(&dr->dr_dirty_node));
1783 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1784 mutex_exit(&dn->dn_mtx);
1785 dnode_setdirty_sc(dn, tx, usesc);
1786 DB_DNODE_EXIT(db);
1787 return (dr);
1788 }
1789
1790 /*
1791 * The dn_struct_rwlock prevents db_blkptr from changing
1792 * due to a write from syncing context completing
1793 * while we are running, so we want to acquire it before
1794 * looking at db_blkptr.
1795 */
1796 if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
1797 rw_enter(&dn->dn_struct_rwlock, RW_READER);
1798 drop_struct_lock = TRUE;
1799 }
1800
1801 /*
1802 * We need to hold the dn_struct_rwlock to make this assertion,
1803 * because it protects dn_phys / dn_next_nlevels from changing.
1804 */
1805 ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) ||
1806 dn->dn_phys->dn_nlevels > db->db_level ||
1807 dn->dn_next_nlevels[txgoff] > db->db_level ||
1808 dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level ||
1809 dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level);
1810
1811 /*
1812 * If we are overwriting a dedup BP, then unless it is snapshotted,
1813 * when we get to syncing context we will need to decrement its
1814 * refcount in the DDT. Prefetch the relevant DDT block so that
1815 * syncing context won't have to wait for the i/o.
1816 */
1817 ddt_prefetch(os->os_spa, db->db_blkptr);
1818
1819 if (db->db_level == 0) {
1820 dnode_new_blkid(dn, db->db_blkid, tx, usesc, drop_struct_lock);
1821 ASSERT(dn->dn_maxblkid >= db->db_blkid);
1822 }
1823
1824 if (db->db_level+1 < dn->dn_nlevels) {
1825 dmu_buf_impl_t *parent = db->db_parent;
1826 dbuf_dirty_record_t *di;
1827 int parent_held = FALSE;
1828
1829 if (db->db_parent == NULL || db->db_parent == dn->dn_dbuf) {
1830 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1831
1832 parent = dbuf_hold_level(dn, db->db_level+1,
1833 db->db_blkid >> epbs, FTAG);
1834 ASSERT(parent != NULL);
1835 parent_held = TRUE;
1836 }
1837 if (drop_struct_lock)
1838 rw_exit(&dn->dn_struct_rwlock);
1839 ASSERT3U(db->db_level+1, ==, parent->db_level);
1840 di = dbuf_dirty_sc(parent, tx, usesc);
1841 if (parent_held)
1842 dbuf_rele(parent, FTAG);
1843
1844 mutex_enter(&db->db_mtx);
1845 /*
1846 * Since we've dropped the mutex, it's possible that
1847 * dbuf_undirty() might have changed this out from under us.
1848 */
1849 if (db->db_last_dirty == dr ||
1850 dn->dn_object == DMU_META_DNODE_OBJECT) {
1851 mutex_enter(&di->dt.di.dr_mtx);
1852 ASSERT3U(di->dr_txg, ==, tx->tx_txg);
1853 ASSERT(!list_link_active(&dr->dr_dirty_node));
1854 list_insert_tail(&di->dt.di.dr_children, dr);
1855 mutex_exit(&di->dt.di.dr_mtx);
1856 dr->dr_parent = di;
1857 }
1858
1859 /*
1860 * Special class usage of dirty dbuf could be changed,
1861 * update the dirty entry.
1862 */
1863 dr->dr_usesc = usesc;
1864 mutex_exit(&db->db_mtx);
1865 } else {
1866 ASSERT(db->db_level+1 == dn->dn_nlevels);
1867 ASSERT(db->db_blkid < dn->dn_nblkptr);
1868 ASSERT(db->db_parent == NULL || db->db_parent == dn->dn_dbuf);
1869 mutex_enter(&dn->dn_mtx);
1870 ASSERT(!list_link_active(&dr->dr_dirty_node));
1871 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1872 mutex_exit(&dn->dn_mtx);
1873 if (drop_struct_lock)
1874 rw_exit(&dn->dn_struct_rwlock);
1875 }
1876
1877 dnode_setdirty_sc(dn, tx, usesc);
1878 DB_DNODE_EXIT(db);
1879 return (dr);
1880 }
1881
1882 dbuf_dirty_record_t *
1883 dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1884 {
1885 spa_t *spa;
1886
1887 ASSERT(db->db_objset != NULL);
1888 spa = db->db_objset->os_spa;
1889
1890 return (dbuf_dirty_sc(db, tx, spa->spa_usesc));
1891 }
1892
1893 /*
1894 * Undirty a buffer in the transaction group referenced by the given
1895 * transaction. Return whether this evicted the dbuf.
1896 */
1897 static boolean_t
1898 dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1899 {
1900 dnode_t *dn;
1901 uint64_t txg = tx->tx_txg;
1902 dbuf_dirty_record_t *dr, **drp;
1903
1904 ASSERT(txg != 0);
1905
1906 /*
1907 * Due to our use of dn_nlevels below, this can only be called
1908 * in open context, unless we are operating on the MOS.
1909 * From syncing context, dn_nlevels may be different from the
1910 * dn_nlevels used when dbuf was dirtied.
1911 */
1912 ASSERT(db->db_objset ==
1913 dmu_objset_pool(db->db_objset)->dp_meta_objset ||
1914 txg != spa_syncing_txg(dmu_objset_spa(db->db_objset)));
1915 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1916 ASSERT0(db->db_level);
1917 ASSERT(MUTEX_HELD(&db->db_mtx));
1918
1919 /*
1920 * If this buffer is not dirty, we're done.
1921 */
1922 for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next)
1923 if (dr->dr_txg <= txg)
1924 break;
1925 if (dr == NULL || dr->dr_txg < txg)
1926 return (B_FALSE);
1927 ASSERT(dr->dr_txg == txg);
1928 ASSERT(dr->dr_dbuf == db);
1929
1930 DB_DNODE_ENTER(db);
1931 dn = DB_DNODE(db);
1932
1933 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1934
1935 ASSERT(db->db.db_size != 0);
1936
1937 dsl_pool_undirty_space(dmu_objset_pool(dn->dn_objset),
1938 dr->dr_accounted, txg);
1939
1940 *drp = dr->dr_next;
1941
1942 /*
1943 * Note that there are three places in dbuf_dirty()
1944 * where this dirty record may be put on a list.
1945 * Make sure to do a list_remove corresponding to
1946 * every one of those list_insert calls.
1947 */
1948 if (dr->dr_parent) {
1949 mutex_enter(&dr->dr_parent->dt.di.dr_mtx);
1950 list_remove(&dr->dr_parent->dt.di.dr_children, dr);
1951 mutex_exit(&dr->dr_parent->dt.di.dr_mtx);
1952 } else if (db->db_blkid == DMU_SPILL_BLKID ||
1953 db->db_level + 1 == dn->dn_nlevels) {
1954 ASSERT(db->db_blkptr == NULL || db->db_parent == dn->dn_dbuf);
1955 mutex_enter(&dn->dn_mtx);
1956 list_remove(&dn->dn_dirty_records[txg & TXG_MASK], dr);
1957 mutex_exit(&dn->dn_mtx);
1958 }
1959 DB_DNODE_EXIT(db);
1960
1961 if (db->db_state != DB_NOFILL) {
1962 dbuf_unoverride(dr);
1963
1964 ASSERT(db->db_buf != NULL);
1965 ASSERT(dr->dt.dl.dr_data != NULL);
1966 if (dr->dt.dl.dr_data != db->db_buf)
1967 arc_buf_destroy(dr->dt.dl.dr_data, db);
1968 }
1969
1970 kmem_free(dr, sizeof (dbuf_dirty_record_t));
1971
1972 ASSERT(db->db_dirtycnt > 0);
1973 db->db_dirtycnt -= 1;
1974
1975 if (refcount_remove(&db->db_holds, (void *)(uintptr_t)txg) == 0) {
1976 ASSERT(db->db_state == DB_NOFILL || arc_released(db->db_buf));
1977 dbuf_destroy(db);
1978 return (B_TRUE);
1979 }
1980
1981 return (B_FALSE);
1982 }
1983
1984 void
1985 dmu_buf_will_dirty(dmu_buf_t *db_fake, dmu_tx_t *tx)
1986 {
1987 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1988 spa_t *spa = db->db_objset->os_spa;
1989 dmu_buf_will_dirty_sc(db_fake, tx, spa->spa_usesc);
1990 }
1991
1992 void
1993 dmu_buf_will_dirty_sc(dmu_buf_t *db_fake, dmu_tx_t *tx, boolean_t usesc)
1994 {
1995 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1996 int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH;
1997
1998 ASSERT(tx->tx_txg != 0);
1999 ASSERT(!refcount_is_zero(&db->db_holds));
2000
2001 /*
2002 * Quick check for dirtyness. For already dirty blocks, this
2003 * reduces runtime of this function by >90%, and overall performance
2004 * by 50% for some workloads (e.g. file deletion with indirect blocks
2005 * cached).
2006 */
2007 mutex_enter(&db->db_mtx);
2008 dbuf_dirty_record_t *dr;
2009 for (dr = db->db_last_dirty;
2010 dr != NULL && dr->dr_txg >= tx->tx_txg; dr = dr->dr_next) {
2011 /*
2012 * It's possible that it is already dirty but not cached,
2013 * because there are some calls to dbuf_dirty() that don't
2014 * go through dmu_buf_will_dirty().
2015 */
2016 if (dr->dr_txg == tx->tx_txg && db->db_state == DB_CACHED) {
2017 /* This dbuf is already dirty and cached. */
2018 dbuf_redirty(dr, usesc);
2019 mutex_exit(&db->db_mtx);
2020 return;
2021 }
2022 }
2023 mutex_exit(&db->db_mtx);
2024
2025 DB_DNODE_ENTER(db);
2026 if (RW_WRITE_HELD(&DB_DNODE(db)->dn_struct_rwlock))
2027 rf |= DB_RF_HAVESTRUCT;
2028 DB_DNODE_EXIT(db);
2029 (void) dbuf_read(db, NULL, rf);
2030 (void) dbuf_dirty_sc(db, tx, usesc);
2031 }
2032
2033
2034 void
2035 dmu_buf_will_not_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
2036 {
2037 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2038
2039 db->db_state = DB_NOFILL;
2040
2041 dmu_buf_will_fill(db_fake, tx);
2042 }
2043
2044 void
2045 dmu_buf_will_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
2046 {
2047 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2048
2049 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
2050 ASSERT(tx->tx_txg != 0);
2051 ASSERT(db->db_level == 0);
2052 ASSERT(!refcount_is_zero(&db->db_holds));
2053
2054 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT ||
2055 dmu_tx_private_ok(tx));
2056
2057 dbuf_noread(db);
2058 (void) dbuf_dirty(db, tx);
2059 }
2060
2061 #pragma weak dmu_buf_fill_done = dbuf_fill_done
2062 /* ARGSUSED */
2063 void
2064 dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx)
2065 {
2066 mutex_enter(&db->db_mtx);
2067 DBUF_VERIFY(db);
2068
2069 if (db->db_state == DB_FILL) {
2070 if (db->db_level == 0 && db->db_freed_in_flight) {
2071 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
2072 /* we were freed while filling */
2073 /* XXX dbuf_undirty? */
2074 bzero(db->db.db_data, db->db.db_size);
2075 db->db_freed_in_flight = FALSE;
2076 }
2077 db->db_state = DB_CACHED;
2078 cv_broadcast(&db->db_changed);
2079 }
2080 mutex_exit(&db->db_mtx);
2081 }
2082
2083 void
2084 dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
2085 bp_embedded_type_t etype, enum zio_compress comp,
2086 int uncompressed_size, int compressed_size, int byteorder,
2087 dmu_tx_t *tx)
2088 {
2089 dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf;
2090 struct dirty_leaf *dl;
2091 dmu_object_type_t type;
2092
2093 if (etype == BP_EMBEDDED_TYPE_DATA) {
2094 ASSERT(spa_feature_is_active(dmu_objset_spa(db->db_objset),
2095 SPA_FEATURE_EMBEDDED_DATA));
2096 }
2097
2098 DB_DNODE_ENTER(db);
2099 type = DB_DNODE(db)->dn_type;
2100 DB_DNODE_EXIT(db);
2101
2102 ASSERT0(db->db_level);
2103 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
2104
2105 dmu_buf_will_not_fill(dbuf, tx);
2106
2107 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
2108 dl = &db->db_last_dirty->dt.dl;
2109 encode_embedded_bp_compressed(&dl->dr_overridden_by,
2110 data, comp, uncompressed_size, compressed_size);
2111 BPE_SET_ETYPE(&dl->dr_overridden_by, etype);
2112 BP_SET_TYPE(&dl->dr_overridden_by, type);
2113 BP_SET_LEVEL(&dl->dr_overridden_by, 0);
2114 BP_SET_BYTEORDER(&dl->dr_overridden_by, byteorder);
2115
2116 dl->dr_override_state = DR_OVERRIDDEN;
2117 dl->dr_overridden_by.blk_birth = db->db_last_dirty->dr_txg;
2118 }
2119
2120 /*
2121 * Directly assign a provided arc buf to a given dbuf if it's not referenced
2122 * by anybody except our caller. Otherwise copy arcbuf's contents to dbuf.
2123 */
2124 void
2125 dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx)
2126 {
2127 ASSERT(!refcount_is_zero(&db->db_holds));
2128 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
2129 ASSERT(db->db_level == 0);
2130 ASSERT3U(dbuf_is_metadata(db), ==, arc_is_metadata(buf));
2131 ASSERT(buf != NULL);
2132 ASSERT(arc_buf_lsize(buf) == db->db.db_size);
2133 ASSERT(tx->tx_txg != 0);
2134
2135 arc_return_buf(buf, db);
2136 ASSERT(arc_released(buf));
2137
2138 mutex_enter(&db->db_mtx);
2139
2140 while (db->db_state == DB_READ || db->db_state == DB_FILL)
2141 cv_wait(&db->db_changed, &db->db_mtx);
2142
2143 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED);
2144
2145 if (db->db_state == DB_CACHED &&
2146 refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) {
2147 mutex_exit(&db->db_mtx);
2148 (void) dbuf_dirty(db, tx);
2149 bcopy(buf->b_data, db->db.db_data, db->db.db_size);
2150 arc_buf_destroy(buf, db);
2151 xuio_stat_wbuf_copied();
2152 return;
2153 }
2154
2155 xuio_stat_wbuf_nocopy();
2156 if (db->db_state == DB_CACHED) {
2157 dbuf_dirty_record_t *dr = db->db_last_dirty;
2158
2159 ASSERT(db->db_buf != NULL);
2160 if (dr != NULL && dr->dr_txg == tx->tx_txg) {
2161 ASSERT(dr->dt.dl.dr_data == db->db_buf);
2162 if (!arc_released(db->db_buf)) {
2163 ASSERT(dr->dt.dl.dr_override_state ==
2164 DR_OVERRIDDEN);
2165 arc_release(db->db_buf, db);
2166 }
2167 dr->dt.dl.dr_data = buf;
2168 arc_buf_destroy(db->db_buf, db);
2169 } else if (dr == NULL || dr->dt.dl.dr_data != db->db_buf) {
2170 arc_release(db->db_buf, db);
2171 arc_buf_destroy(db->db_buf, db);
2172 }
2173 db->db_buf = NULL;
2174 }
2175 ASSERT(db->db_buf == NULL);
2176 dbuf_set_data(db, buf);
2177 db->db_state = DB_FILL;
2178 mutex_exit(&db->db_mtx);
2179 (void) dbuf_dirty(db, tx);
2180 dmu_buf_fill_done(&db->db, tx);
2181 }
2182
2183 void
2184 dbuf_destroy(dmu_buf_impl_t *db)
2185 {
2186 dnode_t *dn;
2187 dmu_buf_impl_t *parent = db->db_parent;
2188 dmu_buf_impl_t *dndb;
2189
2190 ASSERT(MUTEX_HELD(&db->db_mtx));
2191 ASSERT(refcount_is_zero(&db->db_holds));
2192
2193 if (db->db_buf != NULL) {
2194 arc_buf_destroy(db->db_buf, db);
2195 db->db_buf = NULL;
2196 }
2197
2198 if (db->db_blkid == DMU_BONUS_BLKID) {
2199 ASSERT(db->db.db_data != NULL);
2200 zio_buf_free(db->db.db_data, DN_MAX_BONUSLEN);
2201 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
2202 db->db_state = DB_UNCACHED;
2203 }
2204
2205 dbuf_clear_data(db);
2206
2207 if (multilist_link_active(&db->db_cache_link)) {
2208 ASSERT(db->db_caching_status == DB_DBUF_CACHE ||
2209 db->db_caching_status == DB_DBUF_METADATA_CACHE);
2210
2211 multilist_remove(dbuf_caches[db->db_caching_status].cache, db);
2212 (void) refcount_remove_many(
2213 &dbuf_caches[db->db_caching_status].size,
2214 db->db.db_size, db);
2215
2216 db->db_caching_status = DB_NO_CACHE;
2217 }
2218
2219 ASSERT(db->db_state == DB_UNCACHED || db->db_state == DB_NOFILL);
2220 ASSERT(db->db_data_pending == NULL);
2221
2222 db->db_state = DB_EVICTING;
2223 db->db_blkptr = NULL;
2224
2225 /*
2226 * Now that db_state is DB_EVICTING, nobody else can find this via
2227 * the hash table. We can now drop db_mtx, which allows us to
2228 * acquire the dn_dbufs_mtx.
2229 */
2230 mutex_exit(&db->db_mtx);
2231
2232 DB_DNODE_ENTER(db);
2233 dn = DB_DNODE(db);
2234 dndb = dn->dn_dbuf;
2235 if (db->db_blkid != DMU_BONUS_BLKID) {
2236 boolean_t needlock = !MUTEX_HELD(&dn->dn_dbufs_mtx);
2237 if (needlock)
2238 mutex_enter(&dn->dn_dbufs_mtx);
2239 avl_remove(&dn->dn_dbufs, db);
2240 atomic_dec_32(&dn->dn_dbufs_count);
2241 membar_producer();
2242 DB_DNODE_EXIT(db);
2243 if (needlock)
2244 mutex_exit(&dn->dn_dbufs_mtx);
2245 /*
2246 * Decrementing the dbuf count means that the hold corresponding
2247 * to the removed dbuf is no longer discounted in dnode_move(),
2248 * so the dnode cannot be moved until after we release the hold.
2249 * The membar_producer() ensures visibility of the decremented
2250 * value in dnode_move(), since DB_DNODE_EXIT doesn't actually
2251 * release any lock.
2252 */
2253 dnode_rele(dn, db);
2254 db->db_dnode_handle = NULL;
2255
2256 dbuf_hash_remove(db);
2257 } else {
2258 DB_DNODE_EXIT(db);
2259 }
2260
2261 ASSERT(refcount_is_zero(&db->db_holds));
2262
2263 db->db_parent = NULL;
2264
2265 ASSERT(db->db_buf == NULL);
2266 ASSERT(db->db.db_data == NULL);
2267 ASSERT(db->db_hash_next == NULL);
2268 ASSERT(db->db_blkptr == NULL);
2269 ASSERT(db->db_data_pending == NULL);
2270 ASSERT3U(db->db_caching_status, ==, DB_NO_CACHE);
2271 ASSERT(!multilist_link_active(&db->db_cache_link));
2272
2273 kmem_cache_free(dbuf_kmem_cache, db);
2274 arc_space_return(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
2275
2276 /*
2277 * If this dbuf is referenced from an indirect dbuf,
2278 * decrement the ref count on the indirect dbuf.
2279 */
2280 if (parent && parent != dndb)
2281 dbuf_rele(parent, db);
2282 }
2283
2284 /*
2285 * Note: While bpp will always be updated if the function returns success,
2286 * parentp will not be updated if the dnode does not have dn_dbuf filled in;
2287 * this happens when the dnode is the meta-dnode, or a userused or groupused
2288 * object.
2289 */
2290 static int
2291 dbuf_findbp(dnode_t *dn, int level, uint64_t blkid, int fail_sparse,
2292 dmu_buf_impl_t **parentp, blkptr_t **bpp)
2293 {
2294 *parentp = NULL;
2295 *bpp = NULL;
2296
2297 ASSERT(blkid != DMU_BONUS_BLKID);
2298
2299 if (blkid == DMU_SPILL_BLKID) {
2300 mutex_enter(&dn->dn_mtx);
2301 if (dn->dn_have_spill &&
2302 (dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR))
2303 *bpp = &dn->dn_phys->dn_spill;
2304 else
2305 *bpp = NULL;
2306 dbuf_add_ref(dn->dn_dbuf, NULL);
2307 *parentp = dn->dn_dbuf;
2308 mutex_exit(&dn->dn_mtx);
2309 return (0);
2310 }
2311
2312 int nlevels =
2313 (dn->dn_phys->dn_nlevels == 0) ? 1 : dn->dn_phys->dn_nlevels;
2314 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
2315
2316 ASSERT3U(level * epbs, <, 64);
2317 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
2318 /*
2319 * This assertion shouldn't trip as long as the max indirect block size
2320 * is less than 1M. The reason for this is that up to that point,
2321 * the number of levels required to address an entire object with blocks
2322 * of size SPA_MINBLOCKSIZE satisfies nlevels * epbs + 1 <= 64. In
2323 * other words, if N * epbs + 1 > 64, then if (N-1) * epbs + 1 > 55
2324 * (i.e. we can address the entire object), objects will all use at most
2325 * N-1 levels and the assertion won't overflow. However, once epbs is
2326 * 13, 4 * 13 + 1 = 53, but 5 * 13 + 1 = 66. Then, 4 levels will not be
2327 * enough to address an entire object, so objects will have 5 levels,
2328 * but then this assertion will overflow.
2329 *
2330 * All this is to say that if we ever increase DN_MAX_INDBLKSHIFT, we
2331 * need to redo this logic to handle overflows.
2332 */
2333 ASSERT(level >= nlevels ||
2334 ((nlevels - level - 1) * epbs) +
2335 highbit64(dn->dn_phys->dn_nblkptr) <= 64);
2336 if (level >= nlevels ||
2337 blkid >= ((uint64_t)dn->dn_phys->dn_nblkptr <<
2338 ((nlevels - level - 1) * epbs)) ||
2339 (fail_sparse &&
2340 blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))) {
2341 /* the buffer has no parent yet */
2342 return (SET_ERROR(ENOENT));
2343 } else if (level < nlevels-1) {
2344 /* this block is referenced from an indirect block */
2345 int err = dbuf_hold_impl(dn, level+1,
2346 blkid >> epbs, fail_sparse, FALSE, NULL, parentp);
2347 if (err)
2348 return (err);
2349 err = dbuf_read(*parentp, NULL,
2350 (DB_RF_HAVESTRUCT | DB_RF_NOPREFETCH | DB_RF_CANFAIL));
2351 if (err) {
2352 dbuf_rele(*parentp, NULL);
2353 *parentp = NULL;
2354 return (err);
2355 }
2356 *bpp = ((blkptr_t *)(*parentp)->db.db_data) +
2357 (blkid & ((1ULL << epbs) - 1));
2358 if (blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))
2359 ASSERT(BP_IS_HOLE(*bpp));
2360 return (0);
2361 } else {
2362 /* the block is referenced from the dnode */
2363 ASSERT3U(level, ==, nlevels-1);
2364 ASSERT(dn->dn_phys->dn_nblkptr == 0 ||
2365 blkid < dn->dn_phys->dn_nblkptr);
2366 if (dn->dn_dbuf) {
2367 dbuf_add_ref(dn->dn_dbuf, NULL);
2368 *parentp = dn->dn_dbuf;
2369 }
2370 *bpp = &dn->dn_phys->dn_blkptr[blkid];
2371 return (0);
2372 }
2373 }
2374
2375 static dmu_buf_impl_t *
2376 dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid,
2377 dmu_buf_impl_t *parent, blkptr_t *blkptr)
2378 {
2379 objset_t *os = dn->dn_objset;
2380 dmu_buf_impl_t *db, *odb;
2381
2382 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
2383 ASSERT(dn->dn_type != DMU_OT_NONE);
2384
2385 db = kmem_cache_alloc(dbuf_kmem_cache, KM_SLEEP);
2386
2387 db->db_objset = os;
2388 db->db.db_object = dn->dn_object;
2389 db->db_level = level;
2390 db->db_blkid = blkid;
2391 db->db_last_dirty = NULL;
2392 db->db_dirtycnt = 0;
2393 db->db_dnode_handle = dn->dn_handle;
2394 db->db_parent = parent;
2395 db->db_blkptr = blkptr;
2396
2397 db->db_user = NULL;
2398 db->db_user_immediate_evict = FALSE;
2399 db->db_freed_in_flight = FALSE;
2400 db->db_pending_evict = FALSE;
2401
2402 if (blkid == DMU_BONUS_BLKID) {
2403 ASSERT3P(parent, ==, dn->dn_dbuf);
2404 db->db.db_size = DN_MAX_BONUSLEN -
2405 (dn->dn_nblkptr-1) * sizeof (blkptr_t);
2406 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
2407 db->db.db_offset = DMU_BONUS_BLKID;
2408 db->db_state = DB_UNCACHED;
2409 db->db_caching_status = DB_NO_CACHE;
2410 /* the bonus dbuf is not placed in the hash table */
2411 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
2412 return (db);
2413 } else if (blkid == DMU_SPILL_BLKID) {
2414 db->db.db_size = (blkptr != NULL) ?
2415 BP_GET_LSIZE(blkptr) : SPA_MINBLOCKSIZE;
2416 db->db.db_offset = 0;
2417 } else {
2418 int blocksize =
2419 db->db_level ? 1 << dn->dn_indblkshift : dn->dn_datablksz;
2420 db->db.db_size = blocksize;
2421 db->db.db_offset = db->db_blkid * blocksize;
2422 }
2423
2424 /*
2425 * Hold the dn_dbufs_mtx while we get the new dbuf
2426 * in the hash table *and* added to the dbufs list.
2427 * This prevents a possible deadlock with someone
2428 * trying to look up this dbuf before its added to the
2429 * dn_dbufs list.
2430 */
2431 mutex_enter(&dn->dn_dbufs_mtx);
2432 db->db_state = DB_EVICTING;
2433 if ((odb = dbuf_hash_insert(db)) != NULL) {
2434 /* someone else inserted it first */
2435 kmem_cache_free(dbuf_kmem_cache, db);
2436 mutex_exit(&dn->dn_dbufs_mtx);
2437 return (odb);
2438 }
2439 avl_add(&dn->dn_dbufs, db);
2440
2441 db->db_state = DB_UNCACHED;
2442 db->db_caching_status = DB_NO_CACHE;
2443 mutex_exit(&dn->dn_dbufs_mtx);
2444 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
2445
2446 if (parent && parent != dn->dn_dbuf)
2447 dbuf_add_ref(parent, db);
2448
2449 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
2450 refcount_count(&dn->dn_holds) > 0);
2451 (void) refcount_add(&dn->dn_holds, db);
2452 atomic_inc_32(&dn->dn_dbufs_count);
2453
2454 dprintf_dbuf(db, "db=%p\n", db);
2455
2456 return (db);
2457 }
2458
2459 typedef struct dbuf_prefetch_arg {
2460 spa_t *dpa_spa; /* The spa to issue the prefetch in. */
2461 zbookmark_phys_t dpa_zb; /* The target block to prefetch. */
2462 int dpa_epbs; /* Entries (blkptr_t's) Per Block Shift. */
2463 int dpa_curlevel; /* The current level that we're reading */
2464 dnode_t *dpa_dnode; /* The dnode associated with the prefetch */
2465 zio_priority_t dpa_prio; /* The priority I/Os should be issued at. */
2466 zio_t *dpa_zio; /* The parent zio_t for all prefetches. */
2467 arc_flags_t dpa_aflags; /* Flags to pass to the final prefetch. */
2468 } dbuf_prefetch_arg_t;
2469
2470 /*
2471 * Actually issue the prefetch read for the block given.
2472 */
2473 static void
2474 dbuf_issue_final_prefetch(dbuf_prefetch_arg_t *dpa, blkptr_t *bp)
2475 {
2476 if (BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp))
2477 return;
2478
2479 arc_flags_t aflags =
2480 dpa->dpa_aflags | ARC_FLAG_NOWAIT | ARC_FLAG_PREFETCH;
2481
2482 ASSERT3U(dpa->dpa_curlevel, ==, BP_GET_LEVEL(bp));
2483 ASSERT3U(dpa->dpa_curlevel, ==, dpa->dpa_zb.zb_level);
2484 ASSERT(dpa->dpa_zio != NULL);
2485 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa, bp, NULL, NULL,
2486 dpa->dpa_prio, ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
2487 &aflags, &dpa->dpa_zb);
2488 }
2489
2490 /*
2491 * Called when an indirect block above our prefetch target is read in. This
2492 * will either read in the next indirect block down the tree or issue the actual
2493 * prefetch if the next block down is our target.
2494 */
2495 static void
2496 dbuf_prefetch_indirect_done(zio_t *zio, arc_buf_t *abuf, void *private)
2497 {
2498 dbuf_prefetch_arg_t *dpa = private;
2499
2500 ASSERT3S(dpa->dpa_zb.zb_level, <, dpa->dpa_curlevel);
2501 ASSERT3S(dpa->dpa_curlevel, >, 0);
2502
2503 /*
2504 * The dpa_dnode is only valid if we are called with a NULL
2505 * zio. This indicates that the arc_read() returned without
2506 * first calling zio_read() to issue a physical read. Once
2507 * a physical read is made the dpa_dnode must be invalidated
2508 * as the locks guarding it may have been dropped. If the
2509 * dpa_dnode is still valid, then we want to add it to the dbuf
2510 * cache. To do so, we must hold the dbuf associated with the block
2511 * we just prefetched, read its contents so that we associate it
2512 * with an arc_buf_t, and then release it.
2513 */
2514 if (zio != NULL) {
2515 ASSERT3S(BP_GET_LEVEL(zio->io_bp), ==, dpa->dpa_curlevel);
2516 if (zio->io_flags & ZIO_FLAG_RAW) {
2517 ASSERT3U(BP_GET_PSIZE(zio->io_bp), ==, zio->io_size);
2518 } else {
2519 ASSERT3U(BP_GET_LSIZE(zio->io_bp), ==, zio->io_size);
2520 }
2521 ASSERT3P(zio->io_spa, ==, dpa->dpa_spa);
2522
2523 dpa->dpa_dnode = NULL;
2524 } else if (dpa->dpa_dnode != NULL) {
2525 uint64_t curblkid = dpa->dpa_zb.zb_blkid >>
2526 (dpa->dpa_epbs * (dpa->dpa_curlevel -
2527 dpa->dpa_zb.zb_level));
2528 dmu_buf_impl_t *db = dbuf_hold_level(dpa->dpa_dnode,
2529 dpa->dpa_curlevel, curblkid, FTAG);
2530 (void) dbuf_read(db, NULL,
2531 DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH | DB_RF_HAVESTRUCT);
2532 dbuf_rele(db, FTAG);
2533 }
2534
2535 dpa->dpa_curlevel--;
2536
2537 uint64_t nextblkid = dpa->dpa_zb.zb_blkid >>
2538 (dpa->dpa_epbs * (dpa->dpa_curlevel - dpa->dpa_zb.zb_level));
2539 blkptr_t *bp = ((blkptr_t *)abuf->b_data) +
2540 P2PHASE(nextblkid, 1ULL << dpa->dpa_epbs);
2541 if (BP_IS_HOLE(bp) || (zio != NULL && zio->io_error != 0)) {
2542 kmem_free(dpa, sizeof (*dpa));
2543 } else if (dpa->dpa_curlevel == dpa->dpa_zb.zb_level) {
2544 ASSERT3U(nextblkid, ==, dpa->dpa_zb.zb_blkid);
2545 dbuf_issue_final_prefetch(dpa, bp);
2546 kmem_free(dpa, sizeof (*dpa));
2547 } else {
2548 arc_flags_t iter_aflags = ARC_FLAG_NOWAIT;
2549 zbookmark_phys_t zb;
2550
2551 /* flag if L2ARC eligible, l2arc_noprefetch then decides */
2552 if (dpa->dpa_aflags & ARC_FLAG_L2CACHE)
2553 iter_aflags |= ARC_FLAG_L2CACHE;
2554
2555 ASSERT3U(dpa->dpa_curlevel, ==, BP_GET_LEVEL(bp));
2556
2557 SET_BOOKMARK(&zb, dpa->dpa_zb.zb_objset,
2558 dpa->dpa_zb.zb_object, dpa->dpa_curlevel, nextblkid);
2559
2560 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa,
2561 bp, dbuf_prefetch_indirect_done, dpa, dpa->dpa_prio,
2562 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
2563 &iter_aflags, &zb);
2564 }
2565
2566 arc_buf_destroy(abuf, private);
2567 }
2568
2569 /*
2570 * Issue prefetch reads for the given block on the given level. If the indirect
2571 * blocks above that block are not in memory, we will read them in
2572 * asynchronously. As a result, this call never blocks waiting for a read to
2573 * complete.
2574 */
2575 void
2576 dbuf_prefetch(dnode_t *dn, int64_t level, uint64_t blkid, zio_priority_t prio,
2577 arc_flags_t aflags)
2578 {
2579 blkptr_t bp;
2580 int epbs, nlevels, curlevel;
2581 uint64_t curblkid;
2582
2583 ASSERT(blkid != DMU_BONUS_BLKID);
2584 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
2585
2586 if (blkid > dn->dn_maxblkid)
2587 return;
2588
2589 if (dnode_block_freed(dn, blkid))
2590 return;
2591
2592 /*
2593 * This dnode hasn't been written to disk yet, so there's nothing to
2594 * prefetch.
2595 */
2596 nlevels = dn->dn_phys->dn_nlevels;
2597 if (level >= nlevels || dn->dn_phys->dn_nblkptr == 0)
2598 return;
2599
2600 epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2601 if (dn->dn_phys->dn_maxblkid < blkid << (epbs * level))
2602 return;
2603
2604 dmu_buf_impl_t *db = dbuf_find(dn->dn_objset, dn->dn_object,
2605 level, blkid);
2606 if (db != NULL) {
2607 mutex_exit(&db->db_mtx);
2608 /*
2609 * This dbuf already exists. It is either CACHED, or
2610 * (we assume) about to be read or filled.
2611 */
2612 return;
2613 }
2614
2615 /*
2616 * Find the closest ancestor (indirect block) of the target block
2617 * that is present in the cache. In this indirect block, we will
2618 * find the bp that is at curlevel, curblkid.
2619 */
2620 curlevel = level;
2621 curblkid = blkid;
2622 while (curlevel < nlevels - 1) {
2623 int parent_level = curlevel + 1;
2624 uint64_t parent_blkid = curblkid >> epbs;
2625 dmu_buf_impl_t *db;
2626
2627 if (dbuf_hold_impl(dn, parent_level, parent_blkid,
2628 FALSE, TRUE, FTAG, &db) == 0) {
2629 blkptr_t *bpp = db->db_buf->b_data;
2630 bp = bpp[P2PHASE(curblkid, 1 << epbs)];
2631 dbuf_rele(db, FTAG);
2632 break;
2633 }
2634
2635 curlevel = parent_level;
2636 curblkid = parent_blkid;
2637 }
2638
2639 if (curlevel == nlevels - 1) {
2640 /* No cached indirect blocks found. */
2641 ASSERT3U(curblkid, <, dn->dn_phys->dn_nblkptr);
2642 bp = dn->dn_phys->dn_blkptr[curblkid];
2643 }
2644 if (BP_IS_HOLE(&bp))
2645 return;
2646
2647 ASSERT3U(curlevel, ==, BP_GET_LEVEL(&bp));
2648
2649 zio_t *pio = zio_root(dmu_objset_spa(dn->dn_objset), NULL, NULL,
2650 ZIO_FLAG_CANFAIL);
2651
2652 dbuf_prefetch_arg_t *dpa = kmem_zalloc(sizeof (*dpa), KM_SLEEP);
2653 dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset;
2654 SET_BOOKMARK(&dpa->dpa_zb, ds != NULL ? ds->ds_object : DMU_META_OBJSET,
2655 dn->dn_object, level, blkid);
2656 dpa->dpa_curlevel = curlevel;
2657 dpa->dpa_prio = prio;
2658 dpa->dpa_aflags = aflags;
2659 dpa->dpa_spa = dn->dn_objset->os_spa;
2660 dpa->dpa_dnode = dn;
2661 dpa->dpa_epbs = epbs;
2662 dpa->dpa_zio = pio;
2663
2664 /* flag if L2ARC eligible, l2arc_noprefetch then decides */
2665 if (DNODE_LEVEL_IS_L2CACHEABLE(dn, level))
2666 dpa->dpa_aflags |= ARC_FLAG_L2CACHE;
2667
2668 /*
2669 * If we have the indirect just above us, no need to do the asynchronous
2670 * prefetch chain; we'll just run the last step ourselves. If we're at
2671 * a higher level, though, we want to issue the prefetches for all the
2672 * indirect blocks asynchronously, so we can go on with whatever we were
2673 * doing.
2674 */
2675 if (curlevel == level) {
2676 ASSERT3U(curblkid, ==, blkid);
2677 dbuf_issue_final_prefetch(dpa, &bp);
2678 kmem_free(dpa, sizeof (*dpa));
2679 } else {
2680 arc_flags_t iter_aflags = ARC_FLAG_NOWAIT;
2681 zbookmark_phys_t zb;
2682
2683 /* flag if L2ARC eligible, l2arc_noprefetch then decides */
2684 if (DNODE_LEVEL_IS_L2CACHEABLE(dn, level))
2685 iter_aflags |= ARC_FLAG_L2CACHE;
2686
2687 SET_BOOKMARK(&zb, ds != NULL ? ds->ds_object : DMU_META_OBJSET,
2688 dn->dn_object, curlevel, curblkid);
2689 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa,
2690 &bp, dbuf_prefetch_indirect_done, dpa, prio,
2691 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
2692 &iter_aflags, &zb);
2693 }
2694 /*
2695 * We use pio here instead of dpa_zio since it's possible that
2696 * dpa may have already been freed.
2697 */
2698 zio_nowait(pio);
2699 }
2700
2701 /*
2702 * Returns with db_holds incremented, and db_mtx not held.
2703 * Note: dn_struct_rwlock must be held.
2704 */
2705 int
2706 dbuf_hold_impl(dnode_t *dn, uint8_t level, uint64_t blkid,
2707 boolean_t fail_sparse, boolean_t fail_uncached,
2708 void *tag, dmu_buf_impl_t **dbp)
2709 {
2710 dmu_buf_impl_t *db, *parent = NULL;
2711
2712 ASSERT(blkid != DMU_BONUS_BLKID);
2713 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
2714 ASSERT3U(dn->dn_nlevels, >, level);
2715
2716 *dbp = NULL;
2717 top:
2718 /* dbuf_find() returns with db_mtx held */
2719 db = dbuf_find(dn->dn_objset, dn->dn_object, level, blkid);
2720
2721 if (db == NULL) {
2722 blkptr_t *bp = NULL;
2723 int err;
2724
2725 if (fail_uncached)
2726 return (SET_ERROR(ENOENT));
2727
2728 ASSERT3P(parent, ==, NULL);
2729 err = dbuf_findbp(dn, level, blkid, fail_sparse, &parent, &bp);
2730 if (fail_sparse) {
2731 if (err == 0 && bp && BP_IS_HOLE(bp))
2732 err = SET_ERROR(ENOENT);
2733 if (err) {
2734 if (parent)
2735 dbuf_rele(parent, NULL);
2736 return (err);
2737 }
2738 }
2739 if (err && err != ENOENT)
2740 return (err);
2741 db = dbuf_create(dn, level, blkid, parent, bp);
2742 }
2743
2744 if (fail_uncached && db->db_state != DB_CACHED) {
2745 mutex_exit(&db->db_mtx);
2746 return (SET_ERROR(ENOENT));
2747 }
2748
2749 if (db->db_buf != NULL) {
2750 arc_buf_access(db->db_buf);
2751 ASSERT3P(db->db.db_data, ==, db->db_buf->b_data);
2752 }
2753
2754 ASSERT(db->db_buf == NULL || arc_referenced(db->db_buf));
2755
2756 /*
2757 * If this buffer is currently syncing out, and we are are
2758 * still referencing it from db_data, we need to make a copy
2759 * of it in case we decide we want to dirty it again in this txg.
2760 */
2761 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
2762 dn->dn_object != DMU_META_DNODE_OBJECT &&
2763 db->db_state == DB_CACHED && db->db_data_pending) {
2764 dbuf_dirty_record_t *dr = db->db_data_pending;
2765
2766 if (dr->dt.dl.dr_data == db->db_buf) {
2767 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
2768
2769 dbuf_set_data(db,
2770 arc_alloc_buf(dn->dn_objset->os_spa, db, type,
2771 db->db.db_size));
2772 bcopy(dr->dt.dl.dr_data->b_data, db->db.db_data,
2773 db->db.db_size);
2774 }
2775 }
2776
2777 if (multilist_link_active(&db->db_cache_link)) {
2778 ASSERT(refcount_is_zero(&db->db_holds));
2779 ASSERT(db->db_caching_status == DB_DBUF_CACHE ||
2780 db->db_caching_status == DB_DBUF_METADATA_CACHE);
2781
2782 multilist_remove(dbuf_caches[db->db_caching_status].cache, db);
2783 (void) refcount_remove_many(
2784 &dbuf_caches[db->db_caching_status].size,
2785 db->db.db_size, db);
2786
2787 db->db_caching_status = DB_NO_CACHE;
2788 }
2789 (void) refcount_add(&db->db_holds, tag);
2790 DBUF_VERIFY(db);
2791 mutex_exit(&db->db_mtx);
2792
2793 /* NOTE: we can't rele the parent until after we drop the db_mtx */
2794 if (parent)
2795 dbuf_rele(parent, NULL);
2796
2797 ASSERT3P(DB_DNODE(db), ==, dn);
2798 ASSERT3U(db->db_blkid, ==, blkid);
2799 ASSERT3U(db->db_level, ==, level);
2800 *dbp = db;
2801
2802 return (0);
2803 }
2804
2805 dmu_buf_impl_t *
2806 dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag)
2807 {
2808 return (dbuf_hold_level(dn, 0, blkid, tag));
2809 }
2810
2811 dmu_buf_impl_t *
2812 dbuf_hold_level(dnode_t *dn, int level, uint64_t blkid, void *tag)
2813 {
2814 dmu_buf_impl_t *db;
2815 int err = dbuf_hold_impl(dn, level, blkid, FALSE, FALSE, tag, &db);
2816 return (err ? NULL : db);
2817 }
2818
2819 void
2820 dbuf_create_bonus(dnode_t *dn)
2821 {
2822 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
2823
2824 ASSERT(dn->dn_bonus == NULL);
2825 dn->dn_bonus = dbuf_create(dn, 0, DMU_BONUS_BLKID, dn->dn_dbuf, NULL);
2826 }
2827
2828 int
2829 dbuf_spill_set_blksz(dmu_buf_t *db_fake, uint64_t blksz, dmu_tx_t *tx)
2830 {
2831 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2832 dnode_t *dn;
2833
2834 if (db->db_blkid != DMU_SPILL_BLKID)
2835 return (SET_ERROR(ENOTSUP));
2836 if (blksz == 0)
2837 blksz = SPA_MINBLOCKSIZE;
2838 ASSERT3U(blksz, <=, spa_maxblocksize(dmu_objset_spa(db->db_objset)));
2839 blksz = P2ROUNDUP(blksz, SPA_MINBLOCKSIZE);
2840
2841 DB_DNODE_ENTER(db);
2842 dn = DB_DNODE(db);
2843 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
2844 dbuf_new_size(db, blksz, tx);
2845 rw_exit(&dn->dn_struct_rwlock);
2846 DB_DNODE_EXIT(db);
2847
2848 return (0);
2849 }
2850
2851 void
2852 dbuf_rm_spill(dnode_t *dn, dmu_tx_t *tx)
2853 {
2854 dbuf_free_range(dn, DMU_SPILL_BLKID, DMU_SPILL_BLKID, tx);
2855 }
2856
2857 #pragma weak dmu_buf_add_ref = dbuf_add_ref
2858 void
2859 dbuf_add_ref(dmu_buf_impl_t *db, void *tag)
2860 {
2861 int64_t holds = refcount_add(&db->db_holds, tag);
2862 ASSERT3S(holds, >, 1);
2863 }
2864
2865 #pragma weak dmu_buf_try_add_ref = dbuf_try_add_ref
2866 boolean_t
2867 dbuf_try_add_ref(dmu_buf_t *db_fake, objset_t *os, uint64_t obj, uint64_t blkid,
2868 void *tag)
2869 {
2870 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2871 dmu_buf_impl_t *found_db;
2872 boolean_t result = B_FALSE;
2873
2874 if (db->db_blkid == DMU_BONUS_BLKID)
2875 found_db = dbuf_find_bonus(os, obj);
2876 else
2877 found_db = dbuf_find(os, obj, 0, blkid);
2878
2879 if (found_db != NULL) {
2880 if (db == found_db && dbuf_refcount(db) > db->db_dirtycnt) {
2881 (void) refcount_add(&db->db_holds, tag);
2882 result = B_TRUE;
2883 }
2884 mutex_exit(&db->db_mtx);
2885 }
2886 return (result);
2887 }
2888
2889 /*
2890 * If you call dbuf_rele() you had better not be referencing the dnode handle
2891 * unless you have some other direct or indirect hold on the dnode. (An indirect
2892 * hold is a hold on one of the dnode's dbufs, including the bonus buffer.)
2893 * Without that, the dbuf_rele() could lead to a dnode_rele() followed by the
2894 * dnode's parent dbuf evicting its dnode handles.
2895 */
2896 void
2897 dbuf_rele(dmu_buf_impl_t *db, void *tag)
2898 {
2899 mutex_enter(&db->db_mtx);
2900 dbuf_rele_and_unlock(db, tag);
2901 }
2902
2903 void
2904 dmu_buf_rele(dmu_buf_t *db, void *tag)
2905 {
2906 dbuf_rele((dmu_buf_impl_t *)db, tag);
2907 }
2908
2909 /*
2910 * dbuf_rele() for an already-locked dbuf. This is necessary to allow
2911 * db_dirtycnt and db_holds to be updated atomically.
2912 */
2913 void
2914 dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag)
2915 {
2916 int64_t holds;
2917
2918 ASSERT(MUTEX_HELD(&db->db_mtx));
2919 DBUF_VERIFY(db);
2920
2921 /*
2922 * Remove the reference to the dbuf before removing its hold on the
2923 * dnode so we can guarantee in dnode_move() that a referenced bonus
2924 * buffer has a corresponding dnode hold.
2925 */
2926 holds = refcount_remove(&db->db_holds, tag);
2927 ASSERT(holds >= 0);
2928
2929 /*
2930 * We can't freeze indirects if there is a possibility that they
2931 * may be modified in the current syncing context.
2932 */
2933 if (db->db_buf != NULL &&
2934 holds == (db->db_level == 0 ? db->db_dirtycnt : 0)) {
2935 arc_buf_freeze(db->db_buf);
2936 }
2937
2938 if (holds == db->db_dirtycnt &&
2939 db->db_level == 0 && db->db_user_immediate_evict)
2940 dbuf_evict_user(db);
2941
2942 if (holds == 0) {
2943 if (db->db_blkid == DMU_BONUS_BLKID) {
2944 dnode_t *dn;
2945 boolean_t evict_dbuf = db->db_pending_evict;
2946
2947 /*
2948 * If the dnode moves here, we cannot cross this
2949 * barrier until the move completes.
2950 */
2951 DB_DNODE_ENTER(db);
2952
2953 dn = DB_DNODE(db);
2954 atomic_dec_32(&dn->dn_dbufs_count);
2955
2956 /*
2957 * Decrementing the dbuf count means that the bonus
2958 * buffer's dnode hold is no longer discounted in
2959 * dnode_move(). The dnode cannot move until after
2960 * the dnode_rele() below.
2961 */
2962 DB_DNODE_EXIT(db);
2963
2964 /*
2965 * Do not reference db after its lock is dropped.
2966 * Another thread may evict it.
2967 */
2968 mutex_exit(&db->db_mtx);
2969
2970 if (evict_dbuf)
2971 dnode_evict_bonus(dn);
2972
2973 dnode_rele(dn, db);
2974 } else if (db->db_buf == NULL) {
2975 /*
2976 * This is a special case: we never associated this
2977 * dbuf with any data allocated from the ARC.
2978 */
2979 ASSERT(db->db_state == DB_UNCACHED ||
2980 db->db_state == DB_NOFILL);
2981 dbuf_destroy(db);
2982 } else if (arc_released(db->db_buf)) {
2983 /*
2984 * This dbuf has anonymous data associated with it.
2985 */
2986 dbuf_destroy(db);
2987 } else {
2988 boolean_t do_arc_evict = B_FALSE;
2989 blkptr_t bp;
2990 spa_t *spa = dmu_objset_spa(db->db_objset);
2991
2992 if (!DBUF_IS_CACHEABLE(db) &&
2993 db->db_blkptr != NULL &&
2994 !BP_IS_HOLE(db->db_blkptr) &&
2995 !BP_IS_EMBEDDED(db->db_blkptr)) {
2996 do_arc_evict = B_TRUE;
2997 bp = *db->db_blkptr;
2998 }
2999
3000 if (!DBUF_IS_CACHEABLE(db) ||
3001 db->db_pending_evict) {
3002 dbuf_destroy(db);
3003 } else if (!multilist_link_active(&db->db_cache_link)) {
3004 ASSERT3U(db->db_caching_status, ==,
3005 DB_NO_CACHE);
3006
3007 dbuf_cached_state_t dcs =
3008 dbuf_include_in_metadata_cache(db) ?
3009 DB_DBUF_METADATA_CACHE : DB_DBUF_CACHE;
3010 db->db_caching_status = dcs;
3011
3012 multilist_insert(dbuf_caches[dcs].cache, db);
3013 (void) refcount_add_many(&dbuf_caches[dcs].size,
3014 db->db.db_size, db);
3015 mutex_exit(&db->db_mtx);
3016
3017 if (db->db_caching_status == DB_DBUF_CACHE) {
3018 dbuf_evict_notify();
3019 }
3020 }
3021
3022 if (do_arc_evict)
3023 arc_freed(spa, &bp);
3024 }
3025 } else {
3026 mutex_exit(&db->db_mtx);
3027 }
3028
3029 }
3030
3031 #pragma weak dmu_buf_refcount = dbuf_refcount
3032 uint64_t
3033 dbuf_refcount(dmu_buf_impl_t *db)
3034 {
3035 return (refcount_count(&db->db_holds));
3036 }
3037
3038 void *
3039 dmu_buf_replace_user(dmu_buf_t *db_fake, dmu_buf_user_t *old_user,
3040 dmu_buf_user_t *new_user)
3041 {
3042 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
3043
3044 mutex_enter(&db->db_mtx);
3045 dbuf_verify_user(db, DBVU_NOT_EVICTING);
3046 if (db->db_user == old_user)
3047 db->db_user = new_user;
3048 else
3049 old_user = db->db_user;
3050 dbuf_verify_user(db, DBVU_NOT_EVICTING);
3051 mutex_exit(&db->db_mtx);
3052
3053 return (old_user);
3054 }
3055
3056 void *
3057 dmu_buf_set_user(dmu_buf_t *db_fake, dmu_buf_user_t *user)
3058 {
3059 return (dmu_buf_replace_user(db_fake, NULL, user));
3060 }
3061
3062 void *
3063 dmu_buf_set_user_ie(dmu_buf_t *db_fake, dmu_buf_user_t *user)
3064 {
3065 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
3066
3067 db->db_user_immediate_evict = TRUE;
3068 return (dmu_buf_set_user(db_fake, user));
3069 }
3070
3071 void *
3072 dmu_buf_remove_user(dmu_buf_t *db_fake, dmu_buf_user_t *user)
3073 {
3074 return (dmu_buf_replace_user(db_fake, user, NULL));
3075 }
3076
3077 void *
3078 dmu_buf_get_user(dmu_buf_t *db_fake)
3079 {
3080 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
3081
3082 dbuf_verify_user(db, DBVU_NOT_EVICTING);
3083 return (db->db_user);
3084 }
3085
3086 void
3087 dmu_buf_user_evict_wait()
3088 {
3089 taskq_wait(dbu_evict_taskq);
3090 }
3091
3092 blkptr_t *
3093 dmu_buf_get_blkptr(dmu_buf_t *db)
3094 {
3095 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
3096 return (dbi->db_blkptr);
3097 }
3098
3099 objset_t *
3100 dmu_buf_get_objset(dmu_buf_t *db)
3101 {
3102 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
3103 return (dbi->db_objset);
3104 }
3105
3106 dnode_t *
3107 dmu_buf_dnode_enter(dmu_buf_t *db)
3108 {
3109 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
3110 DB_DNODE_ENTER(dbi);
3111 return (DB_DNODE(dbi));
3112 }
3113
3114 void
3115 dmu_buf_dnode_exit(dmu_buf_t *db)
3116 {
3117 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
3118 DB_DNODE_EXIT(dbi);
3119 }
3120
3121 static void
3122 dbuf_check_blkptr(dnode_t *dn, dmu_buf_impl_t *db)
3123 {
3124 /* ASSERT(dmu_tx_is_syncing(tx) */
3125 ASSERT(MUTEX_HELD(&db->db_mtx));
3126
3127 if (db->db_blkptr != NULL)
3128 return;
3129
3130 if (db->db_blkid == DMU_SPILL_BLKID) {
3131 db->db_blkptr = &dn->dn_phys->dn_spill;
3132 BP_ZERO(db->db_blkptr);
3133 return;
3134 }
3135 if (db->db_level == dn->dn_phys->dn_nlevels-1) {
3136 /*
3137 * This buffer was allocated at a time when there was
3138 * no available blkptrs from the dnode, or it was
3139 * inappropriate to hook it in (i.e., nlevels mis-match).
3140 */
3141 ASSERT(db->db_blkid < dn->dn_phys->dn_nblkptr);
3142 ASSERT(db->db_parent == NULL);
3143 db->db_parent = dn->dn_dbuf;
3144 db->db_blkptr = &dn->dn_phys->dn_blkptr[db->db_blkid];
3145 DBUF_VERIFY(db);
3146 } else {
3147 dmu_buf_impl_t *parent = db->db_parent;
3148 int epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
3149
3150 ASSERT(dn->dn_phys->dn_nlevels > 1);
3151 if (parent == NULL) {
3152 mutex_exit(&db->db_mtx);
3153 rw_enter(&dn->dn_struct_rwlock, RW_READER);
3154 parent = dbuf_hold_level(dn, db->db_level + 1,
3155 db->db_blkid >> epbs, db);
3156 rw_exit(&dn->dn_struct_rwlock);
3157 mutex_enter(&db->db_mtx);
3158 db->db_parent = parent;
3159 }
3160 db->db_blkptr = (blkptr_t *)parent->db.db_data +
3161 (db->db_blkid & ((1ULL << epbs) - 1));
3162 DBUF_VERIFY(db);
3163 }
3164 }
3165
3166 static void
3167 dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
3168 {
3169 dmu_buf_impl_t *db = dr->dr_dbuf;
3170 dnode_t *dn;
3171 zio_t *zio;
3172
3173 ASSERT(dmu_tx_is_syncing(tx));
3174
3175 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
3176
3177 mutex_enter(&db->db_mtx);
3178
3179 ASSERT(db->db_level > 0);
3180 DBUF_VERIFY(db);
3181
3182 /* Read the block if it hasn't been read yet. */
3183 if (db->db_buf == NULL) {
3184 mutex_exit(&db->db_mtx);
3185 (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED);
3186 mutex_enter(&db->db_mtx);
3187 }
3188 ASSERT3U(db->db_state, ==, DB_CACHED);
3189 ASSERT(db->db_buf != NULL);
3190
3191 DB_DNODE_ENTER(db);
3192 dn = DB_DNODE(db);
3193 /* Indirect block size must match what the dnode thinks it is. */
3194 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
3195 dbuf_check_blkptr(dn, db);
3196 DB_DNODE_EXIT(db);
3197
3198 /* Provide the pending dirty record to child dbufs */
3199 db->db_data_pending = dr;
3200
3201 mutex_exit(&db->db_mtx);
3202 dbuf_write(dr, db->db_buf, tx);
3203
3204 zio = dr->dr_zio;
3205 mutex_enter(&dr->dt.di.dr_mtx);
3206 dbuf_sync_list(&dr->dt.di.dr_children, db->db_level - 1, tx);
3207 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
3208 mutex_exit(&dr->dt.di.dr_mtx);
3209 zio_nowait(zio);
3210 }
3211
3212 static void
3213 dbuf_sync_leaf(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
3214 {
3215 arc_buf_t **datap = &dr->dt.dl.dr_data;
3216 dmu_buf_impl_t *db = dr->dr_dbuf;
3217 dnode_t *dn;
3218 objset_t *os;
3219 uint64_t txg = tx->tx_txg;
3220
3221 ASSERT(dmu_tx_is_syncing(tx));
3222
3223 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
3224
3225 mutex_enter(&db->db_mtx);
3226 /*
3227 * To be synced, we must be dirtied. But we
3228 * might have been freed after the dirty.
3229 */
3230 if (db->db_state == DB_UNCACHED) {
3231 /* This buffer has been freed since it was dirtied */
3232 ASSERT(db->db.db_data == NULL);
3233 } else if (db->db_state == DB_FILL) {
3234 /* This buffer was freed and is now being re-filled */
3235 ASSERT(db->db.db_data != dr->dt.dl.dr_data);
3236 } else {
3237 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_NOFILL);
3238 }
3239 DBUF_VERIFY(db);
3240
3241 DB_DNODE_ENTER(db);
3242 dn = DB_DNODE(db);
3243
3244 if (db->db_blkid == DMU_SPILL_BLKID) {
3245 mutex_enter(&dn->dn_mtx);
3246 dn->dn_phys->dn_flags |= DNODE_FLAG_SPILL_BLKPTR;
3247 mutex_exit(&dn->dn_mtx);
3248 }
3249
3250 /*
3251 * If this is a bonus buffer, simply copy the bonus data into the
3252 * dnode. It will be written out when the dnode is synced (and it
3253 * will be synced, since it must have been dirty for dbuf_sync to
3254 * be called).
3255 */
3256 if (db->db_blkid == DMU_BONUS_BLKID) {
3257 dbuf_dirty_record_t **drp;
3258
3259 ASSERT(*datap != NULL);
3260 ASSERT0(db->db_level);
3261 ASSERT3U(dn->dn_phys->dn_bonuslen, <=, DN_MAX_BONUSLEN);
3262 bcopy(*datap, DN_BONUS(dn->dn_phys), dn->dn_phys->dn_bonuslen);
3263 DB_DNODE_EXIT(db);
3264
3265 if (*datap != db->db.db_data) {
3266 zio_buf_free(*datap, DN_MAX_BONUSLEN);
3267 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
3268 }
3269 db->db_data_pending = NULL;
3270 drp = &db->db_last_dirty;
3271 while (*drp != dr)
3272 drp = &(*drp)->dr_next;
3273 ASSERT(dr->dr_next == NULL);
3274 ASSERT(dr->dr_dbuf == db);
3275 *drp = dr->dr_next;
3276 kmem_free(dr, sizeof (dbuf_dirty_record_t));
3277 ASSERT(db->db_dirtycnt > 0);
3278 db->db_dirtycnt -= 1;
3279 dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg);
3280 return;
3281 }
3282
3283 os = dn->dn_objset;
3284
3285 /*
3286 * This function may have dropped the db_mtx lock allowing a dmu_sync
3287 * operation to sneak in. As a result, we need to ensure that we
3288 * don't check the dr_override_state until we have returned from
3289 * dbuf_check_blkptr.
3290 */
3291 dbuf_check_blkptr(dn, db);
3292
3293 /*
3294 * If this buffer is in the middle of an immediate write,
3295 * wait for the synchronous IO to complete.
3296 */
3297 while (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC) {
3298 ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
3299 cv_wait(&db->db_changed, &db->db_mtx);
3300 ASSERT(dr->dt.dl.dr_override_state != DR_NOT_OVERRIDDEN);
3301 }
3302
3303 if (db->db_state != DB_NOFILL &&
3304 dn->dn_object != DMU_META_DNODE_OBJECT &&
3305 refcount_count(&db->db_holds) > 1 &&
3306 dr->dt.dl.dr_override_state != DR_OVERRIDDEN &&
3307 *datap == db->db_buf) {
3308 /*
3309 * If this buffer is currently "in use" (i.e., there
3310 * are active holds and db_data still references it),
3311 * then make a copy before we start the write so that
3312 * any modifications from the open txg will not leak
3313 * into this write.
3314 *
3315 * NOTE: this copy does not need to be made for
3316 * objects only modified in the syncing context (e.g.
3317 * DNONE_DNODE blocks).
3318 */
3319 int psize = arc_buf_size(*datap);
3320 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
3321 enum zio_compress compress_type = arc_get_compression(*datap);
3322
3323 if (compress_type == ZIO_COMPRESS_OFF) {
3324 *datap = arc_alloc_buf(os->os_spa, db, type, psize);
3325 } else {
3326 ASSERT3U(type, ==, ARC_BUFC_DATA);
3327 int lsize = arc_buf_lsize(*datap);
3328 *datap = arc_alloc_compressed_buf(os->os_spa, db,
3329 psize, lsize, compress_type);
3330 }
3331 bcopy(db->db.db_data, (*datap)->b_data, psize);
3332 }
3333 db->db_data_pending = dr;
3334
3335 mutex_exit(&db->db_mtx);
3336
3337 dbuf_write(dr, *datap, tx);
3338
3339 ASSERT(!list_link_active(&dr->dr_dirty_node));
3340 if (dn->dn_object == DMU_META_DNODE_OBJECT) {
3341 list_insert_tail(&dn->dn_dirty_records[txg&TXG_MASK], dr);
3342 DB_DNODE_EXIT(db);
3343 } else {
3344 /*
3345 * Although zio_nowait() does not "wait for an IO", it does
3346 * initiate the IO. If this is an empty write it seems plausible
3347 * that the IO could actually be completed before the nowait
3348 * returns. We need to DB_DNODE_EXIT() first in case
3349 * zio_nowait() invalidates the dbuf.
3350 */
3351 DB_DNODE_EXIT(db);
3352 zio_nowait(dr->dr_zio);
3353 }
3354 }
3355
3356 void
3357 dbuf_sync_list(list_t *list, int level, dmu_tx_t *tx)
3358 {
3359 dbuf_dirty_record_t *dr;
3360
3361 while (dr = list_head(list)) {
3362 if (dr->dr_zio != NULL) {
3363 /*
3364 * If we find an already initialized zio then we
3365 * are processing the meta-dnode, and we have finished.
3366 * The dbufs for all dnodes are put back on the list
3367 * during processing, so that we can zio_wait()
3368 * these IOs after initiating all child IOs.
3369 */
3370 ASSERT3U(dr->dr_dbuf->db.db_object, ==,
3371 DMU_META_DNODE_OBJECT);
3372 break;
3373 }
3374 if (dr->dr_dbuf->db_blkid != DMU_BONUS_BLKID &&
3375 dr->dr_dbuf->db_blkid != DMU_SPILL_BLKID) {
3376 VERIFY3U(dr->dr_dbuf->db_level, ==, level);
3377 }
3378 list_remove(list, dr);
3379 if (dr->dr_dbuf->db_level > 0)
3380 dbuf_sync_indirect(dr, tx);
3381 else
3382 dbuf_sync_leaf(dr, tx);
3383 }
3384 }
3385
3386 /* ARGSUSED */
3387 static void
3388 dbuf_write_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
3389 {
3390 dmu_buf_impl_t *db = vdb;
3391 dnode_t *dn;
3392 blkptr_t *bp = zio->io_bp;
3393 blkptr_t *bp_orig = &zio->io_bp_orig;
3394 spa_t *spa = zio->io_spa;
3395 int64_t delta;
3396 uint64_t fill = 0;
3397 int i;
3398
3399 ASSERT3P(db->db_blkptr, !=, NULL);
3400 ASSERT3P(&db->db_data_pending->dr_bp_copy, ==, bp);
3401
3402 DB_DNODE_ENTER(db);
3403 dn = DB_DNODE(db);
3404 delta = bp_get_dsize_sync(spa, bp) - bp_get_dsize_sync(spa, bp_orig);
3405 dnode_diduse_space(dn, delta - zio->io_prev_space_delta);
3406 zio->io_prev_space_delta = delta;
3407
3408 if (bp->blk_birth != 0) {
3409 ASSERT((db->db_blkid != DMU_SPILL_BLKID &&
3410 BP_GET_TYPE(bp) == dn->dn_type) ||
3411 (db->db_blkid == DMU_SPILL_BLKID &&
3412 BP_GET_TYPE(bp) == dn->dn_bonustype) ||
3413 BP_IS_EMBEDDED(bp));
3414 ASSERT(BP_GET_LEVEL(bp) == db->db_level);
3415 }
3416
3417 mutex_enter(&db->db_mtx);
3418
3419 #ifdef ZFS_DEBUG
3420 if (db->db_blkid == DMU_SPILL_BLKID) {
3421 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
3422 ASSERT(!(BP_IS_HOLE(bp)) &&
3423 db->db_blkptr == &dn->dn_phys->dn_spill);
3424 }
3425 #endif
3426
3427 if (db->db_level == 0) {
3428 mutex_enter(&dn->dn_mtx);
3429 if (db->db_blkid > dn->dn_phys->dn_maxblkid &&
3430 db->db_blkid != DMU_SPILL_BLKID)
3431 dn->dn_phys->dn_maxblkid = db->db_blkid;
3432 mutex_exit(&dn->dn_mtx);
3433
3434 if (dn->dn_type == DMU_OT_DNODE) {
3435 dnode_phys_t *dnp = db->db.db_data;
3436 for (i = db->db.db_size >> DNODE_SHIFT; i > 0;
3437 i--, dnp++) {
3438 if (dnp->dn_type != DMU_OT_NONE)
3439 fill++;
3440 }
3441 } else {
3442 if (BP_IS_HOLE(bp)) {
3443 fill = 0;
3444 } else {
3445 fill = 1;
3446 }
3447 }
3448 } else {
3449 blkptr_t *ibp = db->db.db_data;
3450 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
3451 for (i = db->db.db_size >> SPA_BLKPTRSHIFT; i > 0; i--, ibp++) {
3452 if (BP_IS_HOLE(ibp))
3453 continue;
3454 fill += BP_GET_FILL(ibp);
3455 }
3456 }
3457 DB_DNODE_EXIT(db);
3458
3459 if (!BP_IS_EMBEDDED(bp))
3460 bp->blk_fill = fill;
3461
3462 mutex_exit(&db->db_mtx);
3463
3464 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
3465 *db->db_blkptr = *bp;
3466 rw_exit(&dn->dn_struct_rwlock);
3467 }
3468
3469 /* ARGSUSED */
3470 /*
3471 * This function gets called just prior to running through the compression
3472 * stage of the zio pipeline. If we're an indirect block comprised of only
3473 * holes, then we want this indirect to be compressed away to a hole. In
3474 * order to do that we must zero out any information about the holes that
3475 * this indirect points to prior to before we try to compress it.
3476 */
3477 static void
3478 dbuf_write_children_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
3479 {
3480 dmu_buf_impl_t *db = vdb;
3481 dnode_t *dn;
3482 blkptr_t *bp;
3483 unsigned int epbs, i;
3484
3485 ASSERT3U(db->db_level, >, 0);
3486 DB_DNODE_ENTER(db);
3487 dn = DB_DNODE(db);
3488 epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
3489 ASSERT3U(epbs, <, 31);
3490
3491 /* Determine if all our children are holes */
3492 for (i = 0, bp = db->db.db_data; i < 1 << epbs; i++, bp++) {
3493 if (!BP_IS_HOLE(bp))
3494 break;
3495 }
3496
3497 /*
3498 * If all the children are holes, then zero them all out so that
3499 * we may get compressed away.
3500 */
3501 if (i == 1 << epbs) {
3502 /*
3503 * We only found holes. Grab the rwlock to prevent
3504 * anybody from reading the blocks we're about to
3505 * zero out.
3506 */
3507 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
3508 bzero(db->db.db_data, db->db.db_size);
3509 rw_exit(&dn->dn_struct_rwlock);
3510 }
3511 DB_DNODE_EXIT(db);
3512 }
3513
3514 /*
3515 * The SPA will call this callback several times for each zio - once
3516 * for every physical child i/o (zio->io_phys_children times). This
3517 * allows the DMU to monitor the progress of each logical i/o. For example,
3518 * there may be 2 copies of an indirect block, or many fragments of a RAID-Z
3519 * block. There may be a long delay before all copies/fragments are completed,
3520 * so this callback allows us to retire dirty space gradually, as the physical
3521 * i/os complete.
3522 */
3523 /* ARGSUSED */
3524 static void
3525 dbuf_write_physdone(zio_t *zio, arc_buf_t *buf, void *arg)
3526 {
3527 dmu_buf_impl_t *db = arg;
3528 objset_t *os = db->db_objset;
3529 dsl_pool_t *dp = dmu_objset_pool(os);
3530 dbuf_dirty_record_t *dr;
3531 int delta = 0;
3532
3533 dr = db->db_data_pending;
3534 ASSERT3U(dr->dr_txg, ==, zio->io_txg);
3535
3536 /*
3537 * The callback will be called io_phys_children times. Retire one
3538 * portion of our dirty space each time we are called. Any rounding
3539 * error will be cleaned up by dsl_pool_sync()'s call to
3540 * dsl_pool_undirty_space().
3541 */
3542 delta = dr->dr_accounted / zio->io_phys_children;
3543 dsl_pool_undirty_space(dp, delta, zio->io_txg);
3544 }
3545
3546 /* ARGSUSED */
3547 static void
3548 dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb)
3549 {
3550 dmu_buf_impl_t *db = vdb;
3551 blkptr_t *bp_orig = &zio->io_bp_orig;
3552 blkptr_t *bp = db->db_blkptr;
3553 objset_t *os = db->db_objset;
3554 dmu_tx_t *tx = os->os_synctx;
3555 dbuf_dirty_record_t **drp, *dr;
3556
3557 ASSERT0(zio->io_error);
3558 ASSERT(db->db_blkptr == bp);
3559
3560 /*
3561 * For nopwrites and rewrites we ensure that the bp matches our
3562 * original and bypass all the accounting.
3563 */
3564 if (zio->io_flags & (ZIO_FLAG_IO_REWRITE | ZIO_FLAG_NOPWRITE)) {
3565 ASSERT(BP_EQUAL(bp, bp_orig));
3566 } else {
3567 dsl_dataset_t *ds = os->os_dsl_dataset;
3568 (void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE);
3569 dsl_dataset_block_born(ds, bp, tx);
3570 }
3571
3572 mutex_enter(&db->db_mtx);
3573
3574 DBUF_VERIFY(db);
3575
3576 drp = &db->db_last_dirty;
3577 while ((dr = *drp) != db->db_data_pending)
3578 drp = &dr->dr_next;
3579 ASSERT(!list_link_active(&dr->dr_dirty_node));
3580 ASSERT(dr->dr_dbuf == db);
3581 ASSERT(dr->dr_next == NULL);
3582 *drp = dr->dr_next;
3583
3584 #ifdef ZFS_DEBUG
3585 if (db->db_blkid == DMU_SPILL_BLKID) {
3586 dnode_t *dn;
3587
3588 DB_DNODE_ENTER(db);
3589 dn = DB_DNODE(db);
3590 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
3591 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
3592 db->db_blkptr == &dn->dn_phys->dn_spill);
3593 DB_DNODE_EXIT(db);
3594 }
3595 #endif
3596
3597 if (db->db_level == 0) {
3598 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
3599 ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
3600 if (db->db_state != DB_NOFILL) {
3601 if (dr->dt.dl.dr_data != db->db_buf)
3602 arc_buf_destroy(dr->dt.dl.dr_data, db);
3603 }
3604 } else {
3605 dnode_t *dn;
3606
3607 DB_DNODE_ENTER(db);
3608 dn = DB_DNODE(db);
3609 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
3610 ASSERT3U(db->db.db_size, ==, 1 << dn->dn_phys->dn_indblkshift);
3611 if (!BP_IS_HOLE(db->db_blkptr)) {
3612 int epbs =
3613 dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
3614 ASSERT3U(db->db_blkid, <=,
3615 dn->dn_phys->dn_maxblkid >> (db->db_level * epbs));
3616 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==,
3617 db->db.db_size);
3618 }
3619 DB_DNODE_EXIT(db);
3620 mutex_destroy(&dr->dt.di.dr_mtx);
3621 list_destroy(&dr->dt.di.dr_children);
3622 }
3623 kmem_free(dr, sizeof (dbuf_dirty_record_t));
3624
3625 cv_broadcast(&db->db_changed);
3626 ASSERT(db->db_dirtycnt > 0);
3627 db->db_dirtycnt -= 1;
3628 db->db_data_pending = NULL;
3629 dbuf_rele_and_unlock(db, (void *)(uintptr_t)tx->tx_txg);
3630 }
3631
3632 static void
3633 dbuf_write_nofill_ready(zio_t *zio)
3634 {
3635 dbuf_write_ready(zio, NULL, zio->io_private);
3636 }
3637
3638 static void
3639 dbuf_write_nofill_done(zio_t *zio)
3640 {
3641 dbuf_write_done(zio, NULL, zio->io_private);
3642 }
3643
3644 static void
3645 dbuf_write_override_ready(zio_t *zio)
3646 {
3647 dbuf_dirty_record_t *dr = zio->io_private;
3648 dmu_buf_impl_t *db = dr->dr_dbuf;
3649
3650 dbuf_write_ready(zio, NULL, db);
3651 }
3652
3653 static void
3654 dbuf_write_override_done(zio_t *zio)
3655 {
3656 dbuf_dirty_record_t *dr = zio->io_private;
3657 dmu_buf_impl_t *db = dr->dr_dbuf;
3658 blkptr_t *obp = &dr->dt.dl.dr_overridden_by;
3659
3660 mutex_enter(&db->db_mtx);
3661 if (!BP_EQUAL(zio->io_bp, obp)) {
3662 if (!BP_IS_HOLE(obp))
3663 dsl_free(spa_get_dsl(zio->io_spa), zio->io_txg, obp);
3664 arc_release(dr->dt.dl.dr_data, db);
3665 }
3666 mutex_exit(&db->db_mtx);
3667 dbuf_write_done(zio, NULL, db);
3668
3669 if (zio->io_abd != NULL)
3670 abd_put(zio->io_abd);
3671 }
3672
3673 /* Issue I/O to commit a dirty buffer to disk. */
3674 static void
3675 dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx)
3676 {
3677 dmu_buf_impl_t *db = dr->dr_dbuf;
3678 dnode_t *dn;
3679 objset_t *os;
3680 dmu_buf_impl_t *parent = db->db_parent;
3681 uint64_t txg = tx->tx_txg;
3682 zbookmark_phys_t zb;
3683 zio_prop_t zp;
3684 zio_t *zio;
3685 int wp_flag = 0;
3686 zio_smartcomp_info_t sc;
3687
3688 ASSERT(dmu_tx_is_syncing(tx));
3689
3690 DB_DNODE_ENTER(db);
3691 dn = DB_DNODE(db);
3692 os = dn->dn_objset;
3693
3694 dnode_setup_zio_smartcomp(db, &sc);
3695
3696 if (db->db_state != DB_NOFILL) {
3697 if (db->db_level > 0 || dn->dn_type == DMU_OT_DNODE) {
3698 /*
3699 * Private object buffers are released here rather
3700 * than in dbuf_dirty() since they are only modified
3701 * in the syncing context and we don't want the
3702 * overhead of making multiple copies of the data.
3703 */
3704 if (BP_IS_HOLE(db->db_blkptr)) {
3705 arc_buf_thaw(data);
3706 } else {
3707 dbuf_release_bp(db);
3708 }
3709 }
3710 }
3711
3712 if (parent != dn->dn_dbuf) {
3713 /* Our parent is an indirect block. */
3714 /* We have a dirty parent that has been scheduled for write. */
3715 ASSERT(parent && parent->db_data_pending);
3716 /* Our parent's buffer is one level closer to the dnode. */
3717 ASSERT(db->db_level == parent->db_level-1);
3718 /*
3719 * We're about to modify our parent's db_data by modifying
3720 * our block pointer, so the parent must be released.
3721 */
3722 ASSERT(arc_released(parent->db_buf));
3723 zio = parent->db_data_pending->dr_zio;
3724 } else {
3725 /* Our parent is the dnode itself. */
3726 ASSERT((db->db_level == dn->dn_phys->dn_nlevels-1 &&
3727 db->db_blkid != DMU_SPILL_BLKID) ||
3728 (db->db_blkid == DMU_SPILL_BLKID && db->db_level == 0));
3729 if (db->db_blkid != DMU_SPILL_BLKID)
3730 ASSERT3P(db->db_blkptr, ==,
3731 &dn->dn_phys->dn_blkptr[db->db_blkid]);
3732 zio = dn->dn_zio;
3733 }
3734
3735 ASSERT(db->db_level == 0 || data == db->db_buf);
3736 ASSERT3U(db->db_blkptr->blk_birth, <=, txg);
3737 ASSERT(zio);
3738
3739 SET_BOOKMARK(&zb, os->os_dsl_dataset ?
3740 os->os_dsl_dataset->ds_object : DMU_META_OBJSET,
3741 db->db.db_object, db->db_level, db->db_blkid);
3742
3743 if (db->db_blkid == DMU_SPILL_BLKID)
3744 wp_flag = WP_SPILL;
3745 wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0;
3746 WP_SET_SPECIALCLASS(wp_flag, dr->dr_usesc);
3747
3748 dmu_write_policy(os, dn, db->db_level, wp_flag, &zp);
3749 DB_DNODE_EXIT(db);
3750
3751 /*
3752 * We copy the blkptr now (rather than when we instantiate the dirty
3753 * record), because its value can change between open context and
3754 * syncing context. We do not need to hold dn_struct_rwlock to read
3755 * db_blkptr because we are in syncing context.
3756 */
3757 dr->dr_bp_copy = *db->db_blkptr;
3758
3759 if (db->db_level == 0 &&
3760 dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
3761 /*
3762 * The BP for this block has been provided by open context
3763 * (by dmu_sync() or dmu_buf_write_embedded()).
3764 */
3765 abd_t *contents = (data != NULL) ?
3766 abd_get_from_buf(data->b_data, arc_buf_size(data)) : NULL;
3767
3768 dr->dr_zio = zio_write(zio, os->os_spa, txg, &dr->dr_bp_copy,
3769 contents, db->db.db_size, db->db.db_size, &zp,
3770 dbuf_write_override_ready, NULL, NULL,
3771 dbuf_write_override_done,
3772 dr, ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb,
3773 &sc);
3774 mutex_enter(&db->db_mtx);
3775 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
3776 zio_write_override(dr->dr_zio, &dr->dt.dl.dr_overridden_by,
3777 dr->dt.dl.dr_copies, dr->dt.dl.dr_nopwrite);
3778 mutex_exit(&db->db_mtx);
3779 } else if (db->db_state == DB_NOFILL) {
3780 ASSERT(zp.zp_checksum == ZIO_CHECKSUM_OFF ||
3781 zp.zp_checksum == ZIO_CHECKSUM_NOPARITY);
3782 dr->dr_zio = zio_write(zio, os->os_spa, txg,
3783 &dr->dr_bp_copy, NULL, db->db.db_size, db->db.db_size, &zp,
3784 dbuf_write_nofill_ready, NULL, NULL,
3785 dbuf_write_nofill_done, db,
3786 ZIO_PRIORITY_ASYNC_WRITE,
3787 ZIO_FLAG_MUSTSUCCEED | ZIO_FLAG_NODATA, &zb, &sc);
3788 } else {
3789 ASSERT(arc_released(data));
3790
3791 /*
3792 * For indirect blocks, we want to setup the children
3793 * ready callback so that we can properly handle an indirect
3794 * block that only contains holes.
3795 */
3796 arc_done_func_t *children_ready_cb = NULL;
3797 if (db->db_level != 0)
3798 children_ready_cb = dbuf_write_children_ready;
3799
3800 dr->dr_zio = arc_write(zio, os->os_spa, txg,
3801 &dr->dr_bp_copy, data, DBUF_IS_L2CACHEABLE(db),
3802 &zp, dbuf_write_ready, children_ready_cb,
3803 dbuf_write_physdone, dbuf_write_done, db,
3804 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb, &sc);
3805 }
3806 }