1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
24 * Copyright (c) 2012, 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/zio.h>
42 #include <sys/dmu_zfetch.h>
43 #include <sys/sa.h>
44 #include <sys/sa_impl.h>
45 #include <sys/zfeature.h>
46 #include <sys/blkptr.h>
47 #include <sys/range_tree.h>
48 #include <sys/callb.h>
49 #include <sys/abd.h>
50 #include <sys/vdev.h>
51 #include <sys/cityhash.h>
52
53 uint_t zfs_dbuf_evict_key;
54
55 static boolean_t dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
56 static void dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx);
57
58 #ifndef __lint
59 extern inline void dmu_buf_init_user(dmu_buf_user_t *dbu,
60 dmu_buf_evict_func_t *evict_func_sync,
61 dmu_buf_evict_func_t *evict_func_async,
62 dmu_buf_t **clear_on_evict_dbufp);
63 #endif /* ! __lint */
64
65 /*
66 * Global data structures and functions for the dbuf cache.
67 */
68 static kmem_cache_t *dbuf_kmem_cache;
69 static taskq_t *dbu_evict_taskq;
70
71 static kthread_t *dbuf_cache_evict_thread;
72 static kmutex_t dbuf_evict_lock;
73 static kcondvar_t dbuf_evict_cv;
74 static boolean_t dbuf_evict_thread_exit;
75
76 /*
77 * LRU cache of dbufs. The dbuf cache maintains a list of dbufs that
78 * are not currently held but have been recently released. These dbufs
79 * are not eligible for arc eviction until they are aged out of the cache.
80 * Dbufs are added to the dbuf cache once the last hold is released. If a
81 * dbuf is later accessed and still exists in the dbuf cache, then it will
82 * be removed from the cache and later re-added to the head of the cache.
83 * Dbufs that are aged out of the cache will be immediately destroyed and
84 * become eligible for arc eviction.
85 */
86 static multilist_t *dbuf_cache;
87 static refcount_t dbuf_cache_size;
88 uint64_t dbuf_cache_max_bytes = 100 * 1024 * 1024;
89
90 /* Cap the size of the dbuf cache to log2 fraction of arc size. */
91 int dbuf_cache_max_shift = 5;
92
93 /*
94 * The dbuf cache uses a three-stage eviction policy:
95 * - A low water marker designates when the dbuf eviction thread
96 * should stop evicting from the dbuf cache.
97 * - When we reach the maximum size (aka mid water mark), we
98 * signal the eviction thread to run.
99 * - The high water mark indicates when the eviction thread
100 * is unable to keep up with the incoming load and eviction must
101 * happen in the context of the calling thread.
102 *
103 * The dbuf cache:
104 * (max size)
105 * low water mid water hi water
106 * +----------------------------------------+----------+----------+
107 * | | | |
108 * | | | |
109 * | | | |
110 * | | | |
111 * +----------------------------------------+----------+----------+
112 * stop signal evict
113 * evicting eviction directly
114 * thread
115 *
116 * The high and low water marks indicate the operating range for the eviction
117 * thread. The low water mark is, by default, 90% of the total size of the
118 * cache and the high water mark is at 110% (both of these percentages can be
119 * changed by setting dbuf_cache_lowater_pct and dbuf_cache_hiwater_pct,
120 * respectively). The eviction thread will try to ensure that the cache remains
121 * within this range by waking up every second and checking if the cache is
122 * above the low water mark. The thread can also be woken up by callers adding
123 * elements into the cache if the cache is larger than the mid water (i.e max
124 * cache size). Once the eviction thread is woken up and eviction is required,
125 * it will continue evicting buffers until it's able to reduce the cache size
126 * to the low water mark. If the cache size continues to grow and hits the high
127 * water mark, then callers adding elments to the cache will begin to evict
128 * directly from the cache until the cache is no longer above the high water
129 * mark.
130 */
131
132 /*
133 * The percentage above and below the maximum cache size.
134 */
135 uint_t dbuf_cache_hiwater_pct = 10;
136 uint_t dbuf_cache_lowater_pct = 10;
137
138 /* ARGSUSED */
139 static int
140 dbuf_cons(void *vdb, void *unused, int kmflag)
141 {
142 dmu_buf_impl_t *db = vdb;
143 bzero(db, sizeof (dmu_buf_impl_t));
144
145 mutex_init(&db->db_mtx, NULL, MUTEX_DEFAULT, NULL);
146 cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL);
147 multilist_link_init(&db->db_cache_link);
148 refcount_create(&db->db_holds);
149
150 return (0);
151 }
152
153 /* ARGSUSED */
154 static void
155 dbuf_dest(void *vdb, void *unused)
156 {
157 dmu_buf_impl_t *db = vdb;
158 mutex_destroy(&db->db_mtx);
159 cv_destroy(&db->db_changed);
160 ASSERT(!multilist_link_active(&db->db_cache_link));
161 refcount_destroy(&db->db_holds);
162 }
163
164 /*
165 * dbuf hash table routines
166 */
167 static dbuf_hash_table_t dbuf_hash_table;
168
169 static uint64_t dbuf_hash_count;
170
171 /*
172 * We use Cityhash for this. It's fast, and has good hash properties without
173 * requiring any large static buffers.
174 */
175 static uint64_t
176 dbuf_hash(void *os, uint64_t obj, uint8_t lvl, uint64_t blkid)
177 {
178 return (cityhash4((uintptr_t)os, obj, (uint64_t)lvl, blkid));
179 }
180
181 #define DBUF_EQUAL(dbuf, os, obj, level, blkid) \
182 ((dbuf)->db.db_object == (obj) && \
183 (dbuf)->db_objset == (os) && \
184 (dbuf)->db_level == (level) && \
185 (dbuf)->db_blkid == (blkid))
186
187 dmu_buf_impl_t *
188 dbuf_find(objset_t *os, uint64_t obj, uint8_t level, uint64_t blkid)
189 {
190 dbuf_hash_table_t *h = &dbuf_hash_table;
191 uint64_t hv = dbuf_hash(os, obj, level, blkid);
192 uint64_t idx = hv & h->hash_table_mask;
193 dmu_buf_impl_t *db;
194
195 mutex_enter(DBUF_HASH_MUTEX(h, idx));
196 for (db = h->hash_table[idx]; db != NULL; db = db->db_hash_next) {
197 if (DBUF_EQUAL(db, os, obj, level, blkid)) {
198 mutex_enter(&db->db_mtx);
199 if (db->db_state != DB_EVICTING) {
200 mutex_exit(DBUF_HASH_MUTEX(h, idx));
201 return (db);
202 }
203 mutex_exit(&db->db_mtx);
204 }
205 }
206 mutex_exit(DBUF_HASH_MUTEX(h, idx));
207 return (NULL);
208 }
209
210 static dmu_buf_impl_t *
211 dbuf_find_bonus(objset_t *os, uint64_t object)
212 {
213 dnode_t *dn;
214 dmu_buf_impl_t *db = NULL;
215
216 if (dnode_hold(os, object, FTAG, &dn) == 0) {
217 rw_enter(&dn->dn_struct_rwlock, RW_READER);
218 if (dn->dn_bonus != NULL) {
219 db = dn->dn_bonus;
220 mutex_enter(&db->db_mtx);
221 }
222 rw_exit(&dn->dn_struct_rwlock);
223 dnode_rele(dn, FTAG);
224 }
225 return (db);
226 }
227
228 /*
229 * Insert an entry into the hash table. If there is already an element
230 * equal to elem in the hash table, then the already existing element
231 * will be returned and the new element will not be inserted.
232 * Otherwise returns NULL.
233 */
234 static dmu_buf_impl_t *
235 dbuf_hash_insert(dmu_buf_impl_t *db)
236 {
237 dbuf_hash_table_t *h = &dbuf_hash_table;
238 objset_t *os = db->db_objset;
239 uint64_t obj = db->db.db_object;
240 int level = db->db_level;
241 uint64_t blkid = db->db_blkid;
242 uint64_t hv = dbuf_hash(os, obj, level, blkid);
243 uint64_t idx = hv & h->hash_table_mask;
244 dmu_buf_impl_t *dbf;
245
246 mutex_enter(DBUF_HASH_MUTEX(h, idx));
247 for (dbf = h->hash_table[idx]; dbf != NULL; dbf = dbf->db_hash_next) {
248 if (DBUF_EQUAL(dbf, os, obj, level, blkid)) {
249 mutex_enter(&dbf->db_mtx);
250 if (dbf->db_state != DB_EVICTING) {
251 mutex_exit(DBUF_HASH_MUTEX(h, idx));
252 return (dbf);
253 }
254 mutex_exit(&dbf->db_mtx);
255 }
256 }
257
258 mutex_enter(&db->db_mtx);
259 db->db_hash_next = h->hash_table[idx];
260 h->hash_table[idx] = db;
261 mutex_exit(DBUF_HASH_MUTEX(h, idx));
262 atomic_inc_64(&dbuf_hash_count);
263
264 return (NULL);
265 }
266
267 /*
268 * Remove an entry from the hash table. It must be in the EVICTING state.
269 */
270 static void
271 dbuf_hash_remove(dmu_buf_impl_t *db)
272 {
273 dbuf_hash_table_t *h = &dbuf_hash_table;
274 uint64_t hv = dbuf_hash(db->db_objset, db->db.db_object,
275 db->db_level, db->db_blkid);
276 uint64_t idx = hv & h->hash_table_mask;
277 dmu_buf_impl_t *dbf, **dbp;
278
279 /*
280 * We musn't hold db_mtx to maintain lock ordering:
281 * DBUF_HASH_MUTEX > db_mtx.
282 */
283 ASSERT(refcount_is_zero(&db->db_holds));
284 ASSERT(db->db_state == DB_EVICTING);
285 ASSERT(!MUTEX_HELD(&db->db_mtx));
286
287 mutex_enter(DBUF_HASH_MUTEX(h, idx));
288 dbp = &h->hash_table[idx];
289 while ((dbf = *dbp) != db) {
290 dbp = &dbf->db_hash_next;
291 ASSERT(dbf != NULL);
292 }
293 *dbp = db->db_hash_next;
294 db->db_hash_next = NULL;
295 mutex_exit(DBUF_HASH_MUTEX(h, idx));
296 atomic_dec_64(&dbuf_hash_count);
297 }
298
299 typedef enum {
300 DBVU_EVICTING,
301 DBVU_NOT_EVICTING
302 } dbvu_verify_type_t;
303
304 static void
305 dbuf_verify_user(dmu_buf_impl_t *db, dbvu_verify_type_t verify_type)
306 {
307 #ifdef ZFS_DEBUG
308 int64_t holds;
309
310 if (db->db_user == NULL)
311 return;
312
313 /* Only data blocks support the attachment of user data. */
314 ASSERT(db->db_level == 0);
315
316 /* Clients must resolve a dbuf before attaching user data. */
317 ASSERT(db->db.db_data != NULL);
318 ASSERT3U(db->db_state, ==, DB_CACHED);
319
320 holds = refcount_count(&db->db_holds);
321 if (verify_type == DBVU_EVICTING) {
322 /*
323 * Immediate eviction occurs when holds == dirtycnt.
324 * For normal eviction buffers, holds is zero on
325 * eviction, except when dbuf_fix_old_data() calls
326 * dbuf_clear_data(). However, the hold count can grow
327 * during eviction even though db_mtx is held (see
328 * dmu_bonus_hold() for an example), so we can only
329 * test the generic invariant that holds >= dirtycnt.
330 */
331 ASSERT3U(holds, >=, db->db_dirtycnt);
332 } else {
333 if (db->db_user_immediate_evict == TRUE)
334 ASSERT3U(holds, >=, db->db_dirtycnt);
335 else
336 ASSERT3U(holds, >, 0);
337 }
338 #endif
339 }
340
341 static void
342 dbuf_evict_user(dmu_buf_impl_t *db)
343 {
344 dmu_buf_user_t *dbu = db->db_user;
345
346 ASSERT(MUTEX_HELD(&db->db_mtx));
347
348 if (dbu == NULL)
349 return;
350
351 dbuf_verify_user(db, DBVU_EVICTING);
352 db->db_user = NULL;
353
354 #ifdef ZFS_DEBUG
355 if (dbu->dbu_clear_on_evict_dbufp != NULL)
356 *dbu->dbu_clear_on_evict_dbufp = NULL;
357 #endif
358
359 /*
360 * There are two eviction callbacks - one that we call synchronously
361 * and one that we invoke via a taskq. The async one is useful for
362 * avoiding lock order reversals and limiting stack depth.
363 *
364 * Note that if we have a sync callback but no async callback,
365 * it's likely that the sync callback will free the structure
366 * containing the dbu. In that case we need to take care to not
367 * dereference dbu after calling the sync evict func.
368 */
369 boolean_t has_async = (dbu->dbu_evict_func_async != NULL);
370
371 if (dbu->dbu_evict_func_sync != NULL)
372 dbu->dbu_evict_func_sync(dbu);
373
374 if (has_async) {
375 taskq_dispatch_ent(dbu_evict_taskq, dbu->dbu_evict_func_async,
376 dbu, 0, &dbu->dbu_tqent);
377 }
378 }
379
380 boolean_t
381 dbuf_is_metadata(dmu_buf_impl_t *db)
382 {
383 if (db->db_level > 0) {
384 return (B_TRUE);
385 } else {
386 boolean_t is_metadata;
387
388 DB_DNODE_ENTER(db);
389 is_metadata = DMU_OT_IS_METADATA(DB_DNODE(db)->dn_type);
390 DB_DNODE_EXIT(db);
391
392 return (is_metadata);
393 }
394 }
395
396 /*
397 * This function *must* return indices evenly distributed between all
398 * sublists of the multilist. This is needed due to how the dbuf eviction
399 * code is laid out; dbuf_evict_thread() assumes dbufs are evenly
400 * distributed between all sublists and uses this assumption when
401 * deciding which sublist to evict from and how much to evict from it.
402 */
403 unsigned int
404 dbuf_cache_multilist_index_func(multilist_t *ml, void *obj)
405 {
406 dmu_buf_impl_t *db = obj;
407
408 /*
409 * The assumption here, is the hash value for a given
410 * dmu_buf_impl_t will remain constant throughout it's lifetime
411 * (i.e. it's objset, object, level and blkid fields don't change).
412 * Thus, we don't need to store the dbuf's sublist index
413 * on insertion, as this index can be recalculated on removal.
414 *
415 * Also, the low order bits of the hash value are thought to be
416 * distributed evenly. Otherwise, in the case that the multilist
417 * has a power of two number of sublists, each sublists' usage
418 * would not be evenly distributed.
419 */
420 return (dbuf_hash(db->db_objset, db->db.db_object,
421 db->db_level, db->db_blkid) %
422 multilist_get_num_sublists(ml));
423 }
424
425 static inline boolean_t
426 dbuf_cache_above_hiwater(void)
427 {
428 uint64_t dbuf_cache_hiwater_bytes =
429 (dbuf_cache_max_bytes * dbuf_cache_hiwater_pct) / 100;
430
431 return (refcount_count(&dbuf_cache_size) >
432 dbuf_cache_max_bytes + dbuf_cache_hiwater_bytes);
433 }
434
435 static inline boolean_t
436 dbuf_cache_above_lowater(void)
437 {
438 uint64_t dbuf_cache_lowater_bytes =
439 (dbuf_cache_max_bytes * dbuf_cache_lowater_pct) / 100;
440
441 return (refcount_count(&dbuf_cache_size) >
442 dbuf_cache_max_bytes - dbuf_cache_lowater_bytes);
443 }
444
445 /*
446 * Evict the oldest eligible dbuf from the dbuf cache.
447 */
448 static void
449 dbuf_evict_one(void)
450 {
451 int idx = multilist_get_random_index(dbuf_cache);
452 multilist_sublist_t *mls = multilist_sublist_lock(dbuf_cache, idx);
453
454 ASSERT(!MUTEX_HELD(&dbuf_evict_lock));
455
456 /*
457 * Set the thread's tsd to indicate that it's processing evictions.
458 * Once a thread stops evicting from the dbuf cache it will
459 * reset its tsd to NULL.
460 */
461 ASSERT3P(tsd_get(zfs_dbuf_evict_key), ==, NULL);
462 (void) tsd_set(zfs_dbuf_evict_key, (void *)B_TRUE);
463
464 dmu_buf_impl_t *db = multilist_sublist_tail(mls);
465 while (db != NULL && mutex_tryenter(&db->db_mtx) == 0) {
466 db = multilist_sublist_prev(mls, db);
467 }
468
469 DTRACE_PROBE2(dbuf__evict__one, dmu_buf_impl_t *, db,
470 multilist_sublist_t *, mls);
471
472 if (db != NULL) {
473 multilist_sublist_remove(mls, db);
474 multilist_sublist_unlock(mls);
475 (void) refcount_remove_many(&dbuf_cache_size,
476 db->db.db_size, db);
477 dbuf_destroy(db);
478 } else {
479 multilist_sublist_unlock(mls);
480 }
481 (void) tsd_set(zfs_dbuf_evict_key, NULL);
482 }
483
484 /*
485 * The dbuf evict thread is responsible for aging out dbufs from the
486 * cache. Once the cache has reached it's maximum size, dbufs are removed
487 * and destroyed. The eviction thread will continue running until the size
488 * of the dbuf cache is at or below the maximum size. Once the dbuf is aged
489 * out of the cache it is destroyed and becomes eligible for arc eviction.
490 */
491 /* ARGSUSED */
492 static void
493 dbuf_evict_thread(void *unused)
494 {
495 callb_cpr_t cpr;
496
497 CALLB_CPR_INIT(&cpr, &dbuf_evict_lock, callb_generic_cpr, FTAG);
498
499 mutex_enter(&dbuf_evict_lock);
500 while (!dbuf_evict_thread_exit) {
501 while (!dbuf_cache_above_lowater() && !dbuf_evict_thread_exit) {
502 CALLB_CPR_SAFE_BEGIN(&cpr);
503 (void) cv_timedwait_hires(&dbuf_evict_cv,
504 &dbuf_evict_lock, SEC2NSEC(1), MSEC2NSEC(1), 0);
505 CALLB_CPR_SAFE_END(&cpr, &dbuf_evict_lock);
506 }
507 mutex_exit(&dbuf_evict_lock);
508
509 /*
510 * Keep evicting as long as we're above the low water mark
511 * for the cache. We do this without holding the locks to
512 * minimize lock contention.
513 */
514 while (dbuf_cache_above_lowater() && !dbuf_evict_thread_exit) {
515 dbuf_evict_one();
516 }
517
518 mutex_enter(&dbuf_evict_lock);
519 }
520
521 dbuf_evict_thread_exit = B_FALSE;
522 cv_broadcast(&dbuf_evict_cv);
523 CALLB_CPR_EXIT(&cpr); /* drops dbuf_evict_lock */
524 thread_exit();
525 }
526
527 /*
528 * Wake up the dbuf eviction thread if the dbuf cache is at its max size.
529 * If the dbuf cache is at its high water mark, then evict a dbuf from the
530 * dbuf cache using the callers context.
531 */
532 static void
533 dbuf_evict_notify(void)
534 {
535
536 /*
537 * We use thread specific data to track when a thread has
538 * started processing evictions. This allows us to avoid deeply
539 * nested stacks that would have a call flow similar to this:
540 *
541 * dbuf_rele()-->dbuf_rele_and_unlock()-->dbuf_evict_notify()
542 * ^ |
543 * | |
544 * +-----dbuf_destroy()<--dbuf_evict_one()<--------+
545 *
546 * The dbuf_eviction_thread will always have its tsd set until
547 * that thread exits. All other threads will only set their tsd
548 * if they are participating in the eviction process. This only
549 * happens if the eviction thread is unable to process evictions
550 * fast enough. To keep the dbuf cache size in check, other threads
551 * can evict from the dbuf cache directly. Those threads will set
552 * their tsd values so that we ensure that they only evict one dbuf
553 * from the dbuf cache.
554 */
555 if (tsd_get(zfs_dbuf_evict_key) != NULL)
556 return;
557
558 /*
559 * We check if we should evict without holding the dbuf_evict_lock,
560 * because it's OK to occasionally make the wrong decision here,
561 * and grabbing the lock results in massive lock contention.
562 */
563 if (refcount_count(&dbuf_cache_size) > dbuf_cache_max_bytes) {
564 if (dbuf_cache_above_hiwater())
565 dbuf_evict_one();
566 cv_signal(&dbuf_evict_cv);
567 }
568 }
569
570 void
571 dbuf_init(void)
572 {
573 uint64_t hsize = 1ULL << 16;
574 dbuf_hash_table_t *h = &dbuf_hash_table;
575 int i;
576
577 /*
578 * The hash table is big enough to fill all of physical memory
579 * with an average 4K block size. The table will take up
580 * totalmem*sizeof(void*)/4K (i.e. 2MB/GB with 8-byte pointers).
581 */
582 while (hsize * 4096 < physmem * PAGESIZE)
583 hsize <<= 1;
584
585 retry:
586 h->hash_table_mask = hsize - 1;
587 h->hash_table = kmem_zalloc(hsize * sizeof (void *), KM_NOSLEEP);
588 if (h->hash_table == NULL) {
589 /* XXX - we should really return an error instead of assert */
590 ASSERT(hsize > (1ULL << 10));
591 hsize >>= 1;
592 goto retry;
593 }
594
595 dbuf_kmem_cache = kmem_cache_create("dmu_buf_impl_t",
596 sizeof (dmu_buf_impl_t),
597 0, dbuf_cons, dbuf_dest, NULL, NULL, NULL, 0);
598
599 for (i = 0; i < DBUF_MUTEXES; i++)
600 mutex_init(&h->hash_mutexes[i], NULL, MUTEX_DEFAULT, NULL);
601
602 /*
603 * Setup the parameters for the dbuf cache. We cap the size of the
604 * dbuf cache to 1/32nd (default) of the size of the ARC.
605 */
606 dbuf_cache_max_bytes = MIN(dbuf_cache_max_bytes,
607 arc_max_bytes() >> dbuf_cache_max_shift);
608
609 /*
610 * All entries are queued via taskq_dispatch_ent(), so min/maxalloc
611 * configuration is not required.
612 */
613 dbu_evict_taskq = taskq_create("dbu_evict", 1, minclsyspri, 0, 0, 0);
614
615 dbuf_cache = multilist_create(sizeof (dmu_buf_impl_t),
616 offsetof(dmu_buf_impl_t, db_cache_link),
617 dbuf_cache_multilist_index_func);
618 refcount_create(&dbuf_cache_size);
619
620 tsd_create(&zfs_dbuf_evict_key, NULL);
621 dbuf_evict_thread_exit = B_FALSE;
622 mutex_init(&dbuf_evict_lock, NULL, MUTEX_DEFAULT, NULL);
623 cv_init(&dbuf_evict_cv, NULL, CV_DEFAULT, NULL);
624 dbuf_cache_evict_thread = thread_create(NULL, 0, dbuf_evict_thread,
625 NULL, 0, &p0, TS_RUN, minclsyspri);
626 }
627
628 void
629 dbuf_fini(void)
630 {
631 dbuf_hash_table_t *h = &dbuf_hash_table;
632 int i;
633
634 for (i = 0; i < DBUF_MUTEXES; i++)
635 mutex_destroy(&h->hash_mutexes[i]);
636 kmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *));
637 kmem_cache_destroy(dbuf_kmem_cache);
638 taskq_destroy(dbu_evict_taskq);
639
640 mutex_enter(&dbuf_evict_lock);
641 dbuf_evict_thread_exit = B_TRUE;
642 while (dbuf_evict_thread_exit) {
643 cv_signal(&dbuf_evict_cv);
644 cv_wait(&dbuf_evict_cv, &dbuf_evict_lock);
645 }
646 mutex_exit(&dbuf_evict_lock);
647 tsd_destroy(&zfs_dbuf_evict_key);
648
649 mutex_destroy(&dbuf_evict_lock);
650 cv_destroy(&dbuf_evict_cv);
651
652 refcount_destroy(&dbuf_cache_size);
653 multilist_destroy(dbuf_cache);
654 }
655
656 /*
657 * Other stuff.
658 */
659
660 #ifdef ZFS_DEBUG
661 static void
662 dbuf_verify(dmu_buf_impl_t *db)
663 {
664 dnode_t *dn;
665 dbuf_dirty_record_t *dr;
666
667 ASSERT(MUTEX_HELD(&db->db_mtx));
668
669 if (!(zfs_flags & ZFS_DEBUG_DBUF_VERIFY))
670 return;
671
672 ASSERT(db->db_objset != NULL);
673 DB_DNODE_ENTER(db);
674 dn = DB_DNODE(db);
675 if (dn == NULL) {
676 ASSERT(db->db_parent == NULL);
677 ASSERT(db->db_blkptr == NULL);
678 } else {
679 ASSERT3U(db->db.db_object, ==, dn->dn_object);
680 ASSERT3P(db->db_objset, ==, dn->dn_objset);
681 ASSERT3U(db->db_level, <, dn->dn_nlevels);
682 ASSERT(db->db_blkid == DMU_BONUS_BLKID ||
683 db->db_blkid == DMU_SPILL_BLKID ||
684 !avl_is_empty(&dn->dn_dbufs));
685 }
686 if (db->db_blkid == DMU_BONUS_BLKID) {
687 ASSERT(dn != NULL);
688 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
689 ASSERT3U(db->db.db_offset, ==, DMU_BONUS_BLKID);
690 } else if (db->db_blkid == DMU_SPILL_BLKID) {
691 ASSERT(dn != NULL);
692 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
693 ASSERT0(db->db.db_offset);
694 } else {
695 ASSERT3U(db->db.db_offset, ==, db->db_blkid * db->db.db_size);
696 }
697
698 for (dr = db->db_data_pending; dr != NULL; dr = dr->dr_next)
699 ASSERT(dr->dr_dbuf == db);
700
701 for (dr = db->db_last_dirty; dr != NULL; dr = dr->dr_next)
702 ASSERT(dr->dr_dbuf == db);
703
704 /*
705 * We can't assert that db_size matches dn_datablksz because it
706 * can be momentarily different when another thread is doing
707 * dnode_set_blksz().
708 */
709 if (db->db_level == 0 && db->db.db_object == DMU_META_DNODE_OBJECT) {
710 dr = db->db_data_pending;
711 /*
712 * It should only be modified in syncing context, so
713 * make sure we only have one copy of the data.
714 */
715 ASSERT(dr == NULL || dr->dt.dl.dr_data == db->db_buf);
716 }
717
718 /* verify db->db_blkptr */
719 if (db->db_blkptr) {
720 if (db->db_parent == dn->dn_dbuf) {
721 /* db is pointed to by the dnode */
722 /* ASSERT3U(db->db_blkid, <, dn->dn_nblkptr); */
723 if (DMU_OBJECT_IS_SPECIAL(db->db.db_object))
724 ASSERT(db->db_parent == NULL);
725 else
726 ASSERT(db->db_parent != NULL);
727 if (db->db_blkid != DMU_SPILL_BLKID)
728 ASSERT3P(db->db_blkptr, ==,
729 &dn->dn_phys->dn_blkptr[db->db_blkid]);
730 } else {
731 /* db is pointed to by an indirect block */
732 int epb = db->db_parent->db.db_size >> SPA_BLKPTRSHIFT;
733 ASSERT3U(db->db_parent->db_level, ==, db->db_level+1);
734 ASSERT3U(db->db_parent->db.db_object, ==,
735 db->db.db_object);
736 /*
737 * dnode_grow_indblksz() can make this fail if we don't
738 * have the struct_rwlock. XXX indblksz no longer
739 * grows. safe to do this now?
740 */
741 if (RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
742 ASSERT3P(db->db_blkptr, ==,
743 ((blkptr_t *)db->db_parent->db.db_data +
744 db->db_blkid % epb));
745 }
746 }
747 }
748 if ((db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr)) &&
749 (db->db_buf == NULL || db->db_buf->b_data) &&
750 db->db.db_data && db->db_blkid != DMU_BONUS_BLKID &&
751 db->db_state != DB_FILL && !dn->dn_free_txg) {
752 /*
753 * If the blkptr isn't set but they have nonzero data,
754 * it had better be dirty, otherwise we'll lose that
755 * data when we evict this buffer.
756 *
757 * There is an exception to this rule for indirect blocks; in
758 * this case, if the indirect block is a hole, we fill in a few
759 * fields on each of the child blocks (importantly, birth time)
760 * to prevent hole birth times from being lost when you
761 * partially fill in a hole.
762 */
763 if (db->db_dirtycnt == 0) {
764 if (db->db_level == 0) {
765 uint64_t *buf = db->db.db_data;
766 int i;
767
768 for (i = 0; i < db->db.db_size >> 3; i++) {
769 ASSERT(buf[i] == 0);
770 }
771 } else {
772 blkptr_t *bps = db->db.db_data;
773 ASSERT3U(1 << DB_DNODE(db)->dn_indblkshift, ==,
774 db->db.db_size);
775 /*
776 * We want to verify that all the blkptrs in the
777 * indirect block are holes, but we may have
778 * automatically set up a few fields for them.
779 * We iterate through each blkptr and verify
780 * they only have those fields set.
781 */
782 for (int i = 0;
783 i < db->db.db_size / sizeof (blkptr_t);
784 i++) {
785 blkptr_t *bp = &bps[i];
786 ASSERT(ZIO_CHECKSUM_IS_ZERO(
787 &bp->blk_cksum));
788 ASSERT(
789 DVA_IS_EMPTY(&bp->blk_dva[0]) &&
790 DVA_IS_EMPTY(&bp->blk_dva[1]) &&
791 DVA_IS_EMPTY(&bp->blk_dva[2]));
792 ASSERT0(bp->blk_fill);
793 ASSERT0(bp->blk_pad[0]);
794 ASSERT0(bp->blk_pad[1]);
795 ASSERT(!BP_IS_EMBEDDED(bp));
796 ASSERT(BP_IS_HOLE(bp));
797 ASSERT0(bp->blk_phys_birth);
798 }
799 }
800 }
801 }
802 DB_DNODE_EXIT(db);
803 }
804 #endif
805
806 static void
807 dbuf_clear_data(dmu_buf_impl_t *db)
808 {
809 ASSERT(MUTEX_HELD(&db->db_mtx));
810 dbuf_evict_user(db);
811 ASSERT3P(db->db_buf, ==, NULL);
812 db->db.db_data = NULL;
813 if (db->db_state != DB_NOFILL)
814 db->db_state = DB_UNCACHED;
815 }
816
817 static void
818 dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf)
819 {
820 ASSERT(MUTEX_HELD(&db->db_mtx));
821 ASSERT(buf != NULL);
822
823 db->db_buf = buf;
824 ASSERT(buf->b_data != NULL);
825 db->db.db_data = buf->b_data;
826 }
827
828 /*
829 * Loan out an arc_buf for read. Return the loaned arc_buf.
830 */
831 arc_buf_t *
832 dbuf_loan_arcbuf(dmu_buf_impl_t *db)
833 {
834 arc_buf_t *abuf;
835
836 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
837 mutex_enter(&db->db_mtx);
838 if (arc_released(db->db_buf) || refcount_count(&db->db_holds) > 1) {
839 int blksz = db->db.db_size;
840 spa_t *spa = db->db_objset->os_spa;
841
842 mutex_exit(&db->db_mtx);
843 abuf = arc_loan_buf(spa, B_FALSE, blksz);
844 bcopy(db->db.db_data, abuf->b_data, blksz);
845 } else {
846 abuf = db->db_buf;
847 arc_loan_inuse_buf(abuf, db);
848 db->db_buf = NULL;
849 dbuf_clear_data(db);
850 mutex_exit(&db->db_mtx);
851 }
852 return (abuf);
853 }
854
855 /*
856 * Calculate which level n block references the data at the level 0 offset
857 * provided.
858 */
859 uint64_t
860 dbuf_whichblock(dnode_t *dn, int64_t level, uint64_t offset)
861 {
862 if (dn->dn_datablkshift != 0 && dn->dn_indblkshift != 0) {
863 /*
864 * The level n blkid is equal to the level 0 blkid divided by
865 * the number of level 0s in a level n block.
866 *
867 * The level 0 blkid is offset >> datablkshift =
868 * offset / 2^datablkshift.
869 *
870 * The number of level 0s in a level n is the number of block
871 * pointers in an indirect block, raised to the power of level.
872 * This is 2^(indblkshift - SPA_BLKPTRSHIFT)^level =
873 * 2^(level*(indblkshift - SPA_BLKPTRSHIFT)).
874 *
875 * Thus, the level n blkid is: offset /
876 * ((2^datablkshift)*(2^(level*(indblkshift - SPA_BLKPTRSHIFT)))
877 * = offset / 2^(datablkshift + level *
878 * (indblkshift - SPA_BLKPTRSHIFT))
879 * = offset >> (datablkshift + level *
880 * (indblkshift - SPA_BLKPTRSHIFT))
881 */
882 return (offset >> (dn->dn_datablkshift + level *
883 (dn->dn_indblkshift - SPA_BLKPTRSHIFT)));
884 } else {
885 ASSERT3U(offset, <, dn->dn_datablksz);
886 return (0);
887 }
888 }
889
890 static void
891 dbuf_read_done(zio_t *zio, arc_buf_t *buf, void *vdb)
892 {
893 dmu_buf_impl_t *db = vdb;
894
895 mutex_enter(&db->db_mtx);
896 ASSERT3U(db->db_state, ==, DB_READ);
897 /*
898 * All reads are synchronous, so we must have a hold on the dbuf
899 */
900 ASSERT(refcount_count(&db->db_holds) > 0);
901 ASSERT(db->db_buf == NULL);
902 ASSERT(db->db.db_data == NULL);
903 if (db->db_level == 0 && db->db_freed_in_flight) {
904 /* we were freed in flight; disregard any error */
905 arc_release(buf, db);
906 bzero(buf->b_data, db->db.db_size);
907 arc_buf_freeze(buf);
908 db->db_freed_in_flight = FALSE;
909 dbuf_set_data(db, buf);
910 db->db_state = DB_CACHED;
911 } else if (zio == NULL || zio->io_error == 0) {
912 dbuf_set_data(db, buf);
913 db->db_state = DB_CACHED;
914 } else {
915 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
916 ASSERT3P(db->db_buf, ==, NULL);
917 arc_buf_destroy(buf, db);
918 db->db_state = DB_UNCACHED;
919 }
920 cv_broadcast(&db->db_changed);
921 dbuf_rele_and_unlock(db, NULL);
922 }
923
924 static void
925 dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
926 {
927 dnode_t *dn;
928 zbookmark_phys_t zb;
929 arc_flags_t aflags = ARC_FLAG_NOWAIT;
930
931 DB_DNODE_ENTER(db);
932 dn = DB_DNODE(db);
933 ASSERT(!refcount_is_zero(&db->db_holds));
934 /* We need the struct_rwlock to prevent db_blkptr from changing. */
935 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
936 ASSERT(MUTEX_HELD(&db->db_mtx));
937 ASSERT(db->db_state == DB_UNCACHED);
938 ASSERT(db->db_buf == NULL);
939
940 if (db->db_blkid == DMU_BONUS_BLKID) {
941 int bonuslen = MIN(dn->dn_bonuslen, dn->dn_phys->dn_bonuslen);
942
943 ASSERT3U(bonuslen, <=, db->db.db_size);
944 db->db.db_data = zio_buf_alloc(DN_MAX_BONUSLEN);
945 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
946 if (bonuslen < DN_MAX_BONUSLEN)
947 bzero(db->db.db_data, DN_MAX_BONUSLEN);
948 if (bonuslen)
949 bcopy(DN_BONUS(dn->dn_phys), db->db.db_data, bonuslen);
950 DB_DNODE_EXIT(db);
951 db->db_state = DB_CACHED;
952 mutex_exit(&db->db_mtx);
953 return;
954 }
955
956 /*
957 * Recheck BP_IS_HOLE() after dnode_block_freed() in case dnode_sync()
958 * processes the delete record and clears the bp while we are waiting
959 * for the dn_mtx (resulting in a "no" from block_freed).
960 */
961 if (db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr) ||
962 (db->db_level == 0 && (dnode_block_freed(dn, db->db_blkid) ||
963 BP_IS_HOLE(db->db_blkptr)))) {
964 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
965
966 dbuf_set_data(db, arc_alloc_buf(db->db_objset->os_spa, db, type,
967 db->db.db_size));
968 bzero(db->db.db_data, db->db.db_size);
969
970 if (db->db_blkptr != NULL && db->db_level > 0 &&
971 BP_IS_HOLE(db->db_blkptr) &&
972 db->db_blkptr->blk_birth != 0) {
973 blkptr_t *bps = db->db.db_data;
974 for (int i = 0; i < ((1 <<
975 DB_DNODE(db)->dn_indblkshift) / sizeof (blkptr_t));
976 i++) {
977 blkptr_t *bp = &bps[i];
978 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==,
979 1 << dn->dn_indblkshift);
980 BP_SET_LSIZE(bp,
981 BP_GET_LEVEL(db->db_blkptr) == 1 ?
982 dn->dn_datablksz :
983 BP_GET_LSIZE(db->db_blkptr));
984 BP_SET_TYPE(bp, BP_GET_TYPE(db->db_blkptr));
985 BP_SET_LEVEL(bp,
986 BP_GET_LEVEL(db->db_blkptr) - 1);
987 BP_SET_BIRTH(bp, db->db_blkptr->blk_birth, 0);
988 }
989 }
990 DB_DNODE_EXIT(db);
991 db->db_state = DB_CACHED;
992 mutex_exit(&db->db_mtx);
993 return;
994 }
995
996 DB_DNODE_EXIT(db);
997
998 db->db_state = DB_READ;
999 mutex_exit(&db->db_mtx);
1000
1001 if (DBUF_IS_L2CACHEABLE(db))
1002 aflags |= ARC_FLAG_L2CACHE;
1003
1004 SET_BOOKMARK(&zb, db->db_objset->os_dsl_dataset ?
1005 db->db_objset->os_dsl_dataset->ds_object : DMU_META_OBJSET,
1006 db->db.db_object, db->db_level, db->db_blkid);
1007
1008 dbuf_add_ref(db, NULL);
1009
1010 (void) arc_read(zio, db->db_objset->os_spa, db->db_blkptr,
1011 dbuf_read_done, db, ZIO_PRIORITY_SYNC_READ,
1012 (flags & DB_RF_CANFAIL) ? ZIO_FLAG_CANFAIL : ZIO_FLAG_MUSTSUCCEED,
1013 &aflags, &zb);
1014 }
1015
1016 /*
1017 * This is our just-in-time copy function. It makes a copy of buffers that
1018 * have been modified in a previous transaction group before we access them in
1019 * the current active group.
1020 *
1021 * This function is used in three places: when we are dirtying a buffer for the
1022 * first time in a txg, when we are freeing a range in a dnode that includes
1023 * this buffer, and when we are accessing a buffer which was received compressed
1024 * and later referenced in a WRITE_BYREF record.
1025 *
1026 * Note that when we are called from dbuf_free_range() we do not put a hold on
1027 * the buffer, we just traverse the active dbuf list for the dnode.
1028 */
1029 static void
1030 dbuf_fix_old_data(dmu_buf_impl_t *db, uint64_t txg)
1031 {
1032 dbuf_dirty_record_t *dr = db->db_last_dirty;
1033
1034 ASSERT(MUTEX_HELD(&db->db_mtx));
1035 ASSERT(db->db.db_data != NULL);
1036 ASSERT(db->db_level == 0);
1037 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT);
1038
1039 if (dr == NULL ||
1040 (dr->dt.dl.dr_data !=
1041 ((db->db_blkid == DMU_BONUS_BLKID) ? db->db.db_data : db->db_buf)))
1042 return;
1043
1044 /*
1045 * If the last dirty record for this dbuf has not yet synced
1046 * and its referencing the dbuf data, either:
1047 * reset the reference to point to a new copy,
1048 * or (if there a no active holders)
1049 * just null out the current db_data pointer.
1050 */
1051 ASSERT(dr->dr_txg >= txg - 2);
1052 if (db->db_blkid == DMU_BONUS_BLKID) {
1053 /* Note that the data bufs here are zio_bufs */
1054 dr->dt.dl.dr_data = zio_buf_alloc(DN_MAX_BONUSLEN);
1055 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
1056 bcopy(db->db.db_data, dr->dt.dl.dr_data, DN_MAX_BONUSLEN);
1057 } else if (refcount_count(&db->db_holds) > db->db_dirtycnt) {
1058 int size = arc_buf_size(db->db_buf);
1059 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
1060 spa_t *spa = db->db_objset->os_spa;
1061 enum zio_compress compress_type =
1062 arc_get_compression(db->db_buf);
1063
1064 if (compress_type == ZIO_COMPRESS_OFF) {
1065 dr->dt.dl.dr_data = arc_alloc_buf(spa, db, type, size);
1066 } else {
1067 ASSERT3U(type, ==, ARC_BUFC_DATA);
1068 dr->dt.dl.dr_data = arc_alloc_compressed_buf(spa, db,
1069 size, arc_buf_lsize(db->db_buf), compress_type);
1070 }
1071 bcopy(db->db.db_data, dr->dt.dl.dr_data->b_data, size);
1072 } else {
1073 db->db_buf = NULL;
1074 dbuf_clear_data(db);
1075 }
1076 }
1077
1078 int
1079 dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
1080 {
1081 int err = 0;
1082 boolean_t prefetch;
1083 dnode_t *dn;
1084
1085 /*
1086 * We don't have to hold the mutex to check db_state because it
1087 * can't be freed while we have a hold on the buffer.
1088 */
1089 ASSERT(!refcount_is_zero(&db->db_holds));
1090
1091 if (db->db_state == DB_NOFILL)
1092 return (SET_ERROR(EIO));
1093
1094 DB_DNODE_ENTER(db);
1095 dn = DB_DNODE(db);
1096 if ((flags & DB_RF_HAVESTRUCT) == 0)
1097 rw_enter(&dn->dn_struct_rwlock, RW_READER);
1098
1099 prefetch = db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
1100 (flags & DB_RF_NOPREFETCH) == 0 && dn != NULL &&
1101 DBUF_IS_CACHEABLE(db);
1102
1103 mutex_enter(&db->db_mtx);
1104 if (db->db_state == DB_CACHED) {
1105 /*
1106 * If the arc buf is compressed, we need to decompress it to
1107 * read the data. This could happen during the "zfs receive" of
1108 * a stream which is compressed and deduplicated.
1109 */
1110 if (db->db_buf != NULL &&
1111 arc_get_compression(db->db_buf) != ZIO_COMPRESS_OFF) {
1112 dbuf_fix_old_data(db,
1113 spa_syncing_txg(dmu_objset_spa(db->db_objset)));
1114 err = arc_decompress(db->db_buf);
1115 dbuf_set_data(db, db->db_buf);
1116 }
1117 mutex_exit(&db->db_mtx);
1118 if (prefetch)
1119 dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1, B_TRUE);
1120 if ((flags & DB_RF_HAVESTRUCT) == 0)
1121 rw_exit(&dn->dn_struct_rwlock);
1122 DB_DNODE_EXIT(db);
1123 } else if (db->db_state == DB_UNCACHED) {
1124 spa_t *spa = dn->dn_objset->os_spa;
1125 boolean_t need_wait = B_FALSE;
1126
1127 if (zio == NULL &&
1128 db->db_blkptr != NULL && !BP_IS_HOLE(db->db_blkptr)) {
1129 zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL);
1130 need_wait = B_TRUE;
1131 }
1132 dbuf_read_impl(db, zio, flags);
1133
1134 /* dbuf_read_impl has dropped db_mtx for us */
1135
1136 if (prefetch)
1137 dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1, B_TRUE);
1138
1139 if ((flags & DB_RF_HAVESTRUCT) == 0)
1140 rw_exit(&dn->dn_struct_rwlock);
1141 DB_DNODE_EXIT(db);
1142
1143 if (need_wait)
1144 err = zio_wait(zio);
1145 } else {
1146 /*
1147 * Another reader came in while the dbuf was in flight
1148 * between UNCACHED and CACHED. Either a writer will finish
1149 * writing the buffer (sending the dbuf to CACHED) or the
1150 * first reader's request will reach the read_done callback
1151 * and send the dbuf to CACHED. Otherwise, a failure
1152 * occurred and the dbuf went to UNCACHED.
1153 */
1154 mutex_exit(&db->db_mtx);
1155 if (prefetch)
1156 dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1, B_TRUE);
1157 if ((flags & DB_RF_HAVESTRUCT) == 0)
1158 rw_exit(&dn->dn_struct_rwlock);
1159 DB_DNODE_EXIT(db);
1160
1161 /* Skip the wait per the caller's request. */
1162 mutex_enter(&db->db_mtx);
1163 if ((flags & DB_RF_NEVERWAIT) == 0) {
1164 while (db->db_state == DB_READ ||
1165 db->db_state == DB_FILL) {
1166 ASSERT(db->db_state == DB_READ ||
1167 (flags & DB_RF_HAVESTRUCT) == 0);
1168 DTRACE_PROBE2(blocked__read, dmu_buf_impl_t *,
1169 db, zio_t *, zio);
1170 cv_wait(&db->db_changed, &db->db_mtx);
1171 }
1172 if (db->db_state == DB_UNCACHED)
1173 err = SET_ERROR(EIO);
1174 }
1175 mutex_exit(&db->db_mtx);
1176 }
1177
1178 return (err);
1179 }
1180
1181 static void
1182 dbuf_noread(dmu_buf_impl_t *db)
1183 {
1184 ASSERT(!refcount_is_zero(&db->db_holds));
1185 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1186 mutex_enter(&db->db_mtx);
1187 while (db->db_state == DB_READ || db->db_state == DB_FILL)
1188 cv_wait(&db->db_changed, &db->db_mtx);
1189 if (db->db_state == DB_UNCACHED) {
1190 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
1191 spa_t *spa = db->db_objset->os_spa;
1192
1193 ASSERT(db->db_buf == NULL);
1194 ASSERT(db->db.db_data == NULL);
1195 dbuf_set_data(db, arc_alloc_buf(spa, db, type, db->db.db_size));
1196 db->db_state = DB_FILL;
1197 } else if (db->db_state == DB_NOFILL) {
1198 dbuf_clear_data(db);
1199 } else {
1200 ASSERT3U(db->db_state, ==, DB_CACHED);
1201 }
1202 mutex_exit(&db->db_mtx);
1203 }
1204
1205 void
1206 dbuf_unoverride(dbuf_dirty_record_t *dr)
1207 {
1208 dmu_buf_impl_t *db = dr->dr_dbuf;
1209 blkptr_t *bp = &dr->dt.dl.dr_overridden_by;
1210 uint64_t txg = dr->dr_txg;
1211
1212 ASSERT(MUTEX_HELD(&db->db_mtx));
1213 /*
1214 * This assert is valid because dmu_sync() expects to be called by
1215 * a zilog's get_data while holding a range lock. This call only
1216 * comes from dbuf_dirty() callers who must also hold a range lock.
1217 */
1218 ASSERT(dr->dt.dl.dr_override_state != DR_IN_DMU_SYNC);
1219 ASSERT(db->db_level == 0);
1220
1221 if (db->db_blkid == DMU_BONUS_BLKID ||
1222 dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN)
1223 return;
1224
1225 ASSERT(db->db_data_pending != dr);
1226
1227 /* free this block */
1228 if (!BP_IS_HOLE(bp) && !dr->dt.dl.dr_nopwrite)
1229 zio_free(db->db_objset->os_spa, txg, bp);
1230
1231 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
1232 dr->dt.dl.dr_nopwrite = B_FALSE;
1233
1234 /*
1235 * Release the already-written buffer, so we leave it in
1236 * a consistent dirty state. Note that all callers are
1237 * modifying the buffer, so they will immediately do
1238 * another (redundant) arc_release(). Therefore, leave
1239 * the buf thawed to save the effort of freezing &
1240 * immediately re-thawing it.
1241 */
1242 arc_release(dr->dt.dl.dr_data, db);
1243 }
1244
1245 /*
1246 * Evict (if its unreferenced) or clear (if its referenced) any level-0
1247 * data blocks in the free range, so that any future readers will find
1248 * empty blocks.
1249 */
1250 void
1251 dbuf_free_range(dnode_t *dn, uint64_t start_blkid, uint64_t end_blkid,
1252 dmu_tx_t *tx)
1253 {
1254 dmu_buf_impl_t db_search;
1255 dmu_buf_impl_t *db, *db_next;
1256 uint64_t txg = tx->tx_txg;
1257 avl_index_t where;
1258
1259 if (end_blkid > dn->dn_maxblkid &&
1260 !(start_blkid == DMU_SPILL_BLKID || end_blkid == DMU_SPILL_BLKID))
1261 end_blkid = dn->dn_maxblkid;
1262 dprintf_dnode(dn, "start=%llu end=%llu\n", start_blkid, end_blkid);
1263
1264 db_search.db_level = 0;
1265 db_search.db_blkid = start_blkid;
1266 db_search.db_state = DB_SEARCH;
1267
1268 mutex_enter(&dn->dn_dbufs_mtx);
1269 db = avl_find(&dn->dn_dbufs, &db_search, &where);
1270 ASSERT3P(db, ==, NULL);
1271
1272 db = avl_nearest(&dn->dn_dbufs, where, AVL_AFTER);
1273
1274 for (; db != NULL; db = db_next) {
1275 db_next = AVL_NEXT(&dn->dn_dbufs, db);
1276 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1277
1278 if (db->db_level != 0 || db->db_blkid > end_blkid) {
1279 break;
1280 }
1281 ASSERT3U(db->db_blkid, >=, start_blkid);
1282
1283 /* found a level 0 buffer in the range */
1284 mutex_enter(&db->db_mtx);
1285 if (dbuf_undirty(db, tx)) {
1286 /* mutex has been dropped and dbuf destroyed */
1287 continue;
1288 }
1289
1290 if (db->db_state == DB_UNCACHED ||
1291 db->db_state == DB_NOFILL ||
1292 db->db_state == DB_EVICTING) {
1293 ASSERT(db->db.db_data == NULL);
1294 mutex_exit(&db->db_mtx);
1295 continue;
1296 }
1297 if (db->db_state == DB_READ || db->db_state == DB_FILL) {
1298 /* will be handled in dbuf_read_done or dbuf_rele */
1299 db->db_freed_in_flight = TRUE;
1300 mutex_exit(&db->db_mtx);
1301 continue;
1302 }
1303 if (refcount_count(&db->db_holds) == 0) {
1304 ASSERT(db->db_buf);
1305 dbuf_destroy(db);
1306 continue;
1307 }
1308 /* The dbuf is referenced */
1309
1310 if (db->db_last_dirty != NULL) {
1311 dbuf_dirty_record_t *dr = db->db_last_dirty;
1312
1313 if (dr->dr_txg == txg) {
1314 /*
1315 * This buffer is "in-use", re-adjust the file
1316 * size to reflect that this buffer may
1317 * contain new data when we sync.
1318 */
1319 if (db->db_blkid != DMU_SPILL_BLKID &&
1320 db->db_blkid > dn->dn_maxblkid)
1321 dn->dn_maxblkid = db->db_blkid;
1322 dbuf_unoverride(dr);
1323 } else {
1324 /*
1325 * This dbuf is not dirty in the open context.
1326 * Either uncache it (if its not referenced in
1327 * the open context) or reset its contents to
1328 * empty.
1329 */
1330 dbuf_fix_old_data(db, txg);
1331 }
1332 }
1333 /* clear the contents if its cached */
1334 if (db->db_state == DB_CACHED) {
1335 ASSERT(db->db.db_data != NULL);
1336 arc_release(db->db_buf, db);
1337 bzero(db->db.db_data, db->db.db_size);
1338 arc_buf_freeze(db->db_buf);
1339 }
1340
1341 mutex_exit(&db->db_mtx);
1342 }
1343 mutex_exit(&dn->dn_dbufs_mtx);
1344 }
1345
1346 void
1347 dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx)
1348 {
1349 arc_buf_t *buf, *obuf;
1350 int osize = db->db.db_size;
1351 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
1352 dnode_t *dn;
1353
1354 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1355
1356 DB_DNODE_ENTER(db);
1357 dn = DB_DNODE(db);
1358
1359 /* XXX does *this* func really need the lock? */
1360 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
1361
1362 /*
1363 * This call to dmu_buf_will_dirty() with the dn_struct_rwlock held
1364 * is OK, because there can be no other references to the db
1365 * when we are changing its size, so no concurrent DB_FILL can
1366 * be happening.
1367 */
1368 /*
1369 * XXX we should be doing a dbuf_read, checking the return
1370 * value and returning that up to our callers
1371 */
1372 dmu_buf_will_dirty(&db->db, tx);
1373
1374 /* create the data buffer for the new block */
1375 buf = arc_alloc_buf(dn->dn_objset->os_spa, db, type, size);
1376
1377 /* copy old block data to the new block */
1378 obuf = db->db_buf;
1379 bcopy(obuf->b_data, buf->b_data, MIN(osize, size));
1380 /* zero the remainder */
1381 if (size > osize)
1382 bzero((uint8_t *)buf->b_data + osize, size - osize);
1383
1384 mutex_enter(&db->db_mtx);
1385 dbuf_set_data(db, buf);
1386 arc_buf_destroy(obuf, db);
1387 db->db.db_size = size;
1388
1389 if (db->db_level == 0) {
1390 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
1391 db->db_last_dirty->dt.dl.dr_data = buf;
1392 }
1393 mutex_exit(&db->db_mtx);
1394
1395 dmu_objset_willuse_space(dn->dn_objset, size - osize, tx);
1396 DB_DNODE_EXIT(db);
1397 }
1398
1399 void
1400 dbuf_release_bp(dmu_buf_impl_t *db)
1401 {
1402 objset_t *os = db->db_objset;
1403
1404 ASSERT(dsl_pool_sync_context(dmu_objset_pool(os)));
1405 ASSERT(arc_released(os->os_phys_buf) ||
1406 list_link_active(&os->os_dsl_dataset->ds_synced_link));
1407 ASSERT(db->db_parent == NULL || arc_released(db->db_parent->db_buf));
1408
1409 (void) arc_release(db->db_buf, db);
1410 }
1411
1412 /*
1413 * We already have a dirty record for this TXG, and we are being
1414 * dirtied again.
1415 */
1416 static void
1417 dbuf_redirty(dbuf_dirty_record_t *dr)
1418 {
1419 dmu_buf_impl_t *db = dr->dr_dbuf;
1420
1421 ASSERT(MUTEX_HELD(&db->db_mtx));
1422
1423 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID) {
1424 /*
1425 * If this buffer has already been written out,
1426 * we now need to reset its state.
1427 */
1428 dbuf_unoverride(dr);
1429 if (db->db.db_object != DMU_META_DNODE_OBJECT &&
1430 db->db_state != DB_NOFILL) {
1431 /* Already released on initial dirty, so just thaw. */
1432 ASSERT(arc_released(db->db_buf));
1433 arc_buf_thaw(db->db_buf);
1434 }
1435 }
1436 }
1437
1438 dbuf_dirty_record_t *
1439 dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1440 {
1441 dnode_t *dn;
1442 objset_t *os;
1443 dbuf_dirty_record_t **drp, *dr;
1444 int drop_struct_lock = FALSE;
1445 int txgoff = tx->tx_txg & TXG_MASK;
1446
1447 ASSERT(tx->tx_txg != 0);
1448 ASSERT(!refcount_is_zero(&db->db_holds));
1449 DMU_TX_DIRTY_BUF(tx, db);
1450
1451 DB_DNODE_ENTER(db);
1452 dn = DB_DNODE(db);
1453 /*
1454 * Shouldn't dirty a regular buffer in syncing context. Private
1455 * objects may be dirtied in syncing context, but only if they
1456 * were already pre-dirtied in open context.
1457 */
1458 #ifdef DEBUG
1459 if (dn->dn_objset->os_dsl_dataset != NULL) {
1460 rrw_enter(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock,
1461 RW_READER, FTAG);
1462 }
1463 ASSERT(!dmu_tx_is_syncing(tx) ||
1464 BP_IS_HOLE(dn->dn_objset->os_rootbp) ||
1465 DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1466 dn->dn_objset->os_dsl_dataset == NULL);
1467 if (dn->dn_objset->os_dsl_dataset != NULL)
1468 rrw_exit(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock, FTAG);
1469 #endif
1470 /*
1471 * We make this assert for private objects as well, but after we
1472 * check if we're already dirty. They are allowed to re-dirty
1473 * in syncing context.
1474 */
1475 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1476 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1477 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1478
1479 mutex_enter(&db->db_mtx);
1480 /*
1481 * XXX make this true for indirects too? The problem is that
1482 * transactions created with dmu_tx_create_assigned() from
1483 * syncing context don't bother holding ahead.
1484 */
1485 ASSERT(db->db_level != 0 ||
1486 db->db_state == DB_CACHED || db->db_state == DB_FILL ||
1487 db->db_state == DB_NOFILL);
1488
1489 mutex_enter(&dn->dn_mtx);
1490 /*
1491 * Don't set dirtyctx to SYNC if we're just modifying this as we
1492 * initialize the objset.
1493 */
1494 if (dn->dn_dirtyctx == DN_UNDIRTIED) {
1495 if (dn->dn_objset->os_dsl_dataset != NULL) {
1496 rrw_enter(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock,
1497 RW_READER, FTAG);
1498 }
1499 if (!BP_IS_HOLE(dn->dn_objset->os_rootbp)) {
1500 dn->dn_dirtyctx = (dmu_tx_is_syncing(tx) ?
1501 DN_DIRTY_SYNC : DN_DIRTY_OPEN);
1502 ASSERT(dn->dn_dirtyctx_firstset == NULL);
1503 dn->dn_dirtyctx_firstset = kmem_alloc(1, KM_SLEEP);
1504 }
1505 if (dn->dn_objset->os_dsl_dataset != NULL) {
1506 rrw_exit(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock,
1507 FTAG);
1508 }
1509 }
1510 mutex_exit(&dn->dn_mtx);
1511
1512 if (db->db_blkid == DMU_SPILL_BLKID)
1513 dn->dn_have_spill = B_TRUE;
1514
1515 /*
1516 * If this buffer is already dirty, we're done.
1517 */
1518 drp = &db->db_last_dirty;
1519 ASSERT(*drp == NULL || (*drp)->dr_txg <= tx->tx_txg ||
1520 db->db.db_object == DMU_META_DNODE_OBJECT);
1521 while ((dr = *drp) != NULL && dr->dr_txg > tx->tx_txg)
1522 drp = &dr->dr_next;
1523 if (dr && dr->dr_txg == tx->tx_txg) {
1524 DB_DNODE_EXIT(db);
1525
1526 dbuf_redirty(dr);
1527 mutex_exit(&db->db_mtx);
1528 return (dr);
1529 }
1530
1531 /*
1532 * Only valid if not already dirty.
1533 */
1534 ASSERT(dn->dn_object == 0 ||
1535 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
1536 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
1537
1538 ASSERT3U(dn->dn_nlevels, >, db->db_level);
1539
1540 /*
1541 * We should only be dirtying in syncing context if it's the
1542 * mos or we're initializing the os or it's a special object.
1543 * However, we are allowed to dirty in syncing context provided
1544 * we already dirtied it in open context. Hence we must make
1545 * this assertion only if we're not already dirty.
1546 */
1547 os = dn->dn_objset;
1548 VERIFY3U(tx->tx_txg, <=, spa_final_dirty_txg(os->os_spa));
1549 #ifdef DEBUG
1550 if (dn->dn_objset->os_dsl_dataset != NULL)
1551 rrw_enter(&os->os_dsl_dataset->ds_bp_rwlock, RW_READER, FTAG);
1552 ASSERT(!dmu_tx_is_syncing(tx) || DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
1553 os->os_dsl_dataset == NULL || BP_IS_HOLE(os->os_rootbp));
1554 if (dn->dn_objset->os_dsl_dataset != NULL)
1555 rrw_exit(&os->os_dsl_dataset->ds_bp_rwlock, FTAG);
1556 #endif
1557 ASSERT(db->db.db_size != 0);
1558
1559 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1560
1561 if (db->db_blkid != DMU_BONUS_BLKID) {
1562 dmu_objset_willuse_space(os, db->db.db_size, tx);
1563 }
1564
1565 /*
1566 * If this buffer is dirty in an old transaction group we need
1567 * to make a copy of it so that the changes we make in this
1568 * transaction group won't leak out when we sync the older txg.
1569 */
1570 dr = kmem_zalloc(sizeof (dbuf_dirty_record_t), KM_SLEEP);
1571 if (db->db_level == 0) {
1572 void *data_old = db->db_buf;
1573
1574 if (db->db_state != DB_NOFILL) {
1575 if (db->db_blkid == DMU_BONUS_BLKID) {
1576 dbuf_fix_old_data(db, tx->tx_txg);
1577 data_old = db->db.db_data;
1578 } else if (db->db.db_object != DMU_META_DNODE_OBJECT) {
1579 /*
1580 * Release the data buffer from the cache so
1581 * that we can modify it without impacting
1582 * possible other users of this cached data
1583 * block. Note that indirect blocks and
1584 * private objects are not released until the
1585 * syncing state (since they are only modified
1586 * then).
1587 */
1588 arc_release(db->db_buf, db);
1589 dbuf_fix_old_data(db, tx->tx_txg);
1590 data_old = db->db_buf;
1591 }
1592 ASSERT(data_old != NULL);
1593 }
1594 dr->dt.dl.dr_data = data_old;
1595 } else {
1596 mutex_init(&dr->dt.di.dr_mtx, NULL, MUTEX_DEFAULT, NULL);
1597 list_create(&dr->dt.di.dr_children,
1598 sizeof (dbuf_dirty_record_t),
1599 offsetof(dbuf_dirty_record_t, dr_dirty_node));
1600 }
1601 if (db->db_blkid != DMU_BONUS_BLKID && os->os_dsl_dataset != NULL)
1602 dr->dr_accounted = db->db.db_size;
1603 dr->dr_dbuf = db;
1604 dr->dr_txg = tx->tx_txg;
1605 dr->dr_next = *drp;
1606 *drp = dr;
1607
1608 /*
1609 * We could have been freed_in_flight between the dbuf_noread
1610 * and dbuf_dirty. We win, as though the dbuf_noread() had
1611 * happened after the free.
1612 */
1613 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
1614 db->db_blkid != DMU_SPILL_BLKID) {
1615 mutex_enter(&dn->dn_mtx);
1616 if (dn->dn_free_ranges[txgoff] != NULL) {
1617 range_tree_clear(dn->dn_free_ranges[txgoff],
1618 db->db_blkid, 1);
1619 }
1620 mutex_exit(&dn->dn_mtx);
1621 db->db_freed_in_flight = FALSE;
1622 }
1623
1624 /*
1625 * This buffer is now part of this txg
1626 */
1627 dbuf_add_ref(db, (void *)(uintptr_t)tx->tx_txg);
1628 db->db_dirtycnt += 1;
1629 ASSERT3U(db->db_dirtycnt, <=, 3);
1630
1631 mutex_exit(&db->db_mtx);
1632
1633 if (db->db_blkid == DMU_BONUS_BLKID ||
1634 db->db_blkid == DMU_SPILL_BLKID) {
1635 mutex_enter(&dn->dn_mtx);
1636 ASSERT(!list_link_active(&dr->dr_dirty_node));
1637 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1638 mutex_exit(&dn->dn_mtx);
1639 dnode_setdirty(dn, tx);
1640 DB_DNODE_EXIT(db);
1641 return (dr);
1642 }
1643
1644 /*
1645 * The dn_struct_rwlock prevents db_blkptr from changing
1646 * due to a write from syncing context completing
1647 * while we are running, so we want to acquire it before
1648 * looking at db_blkptr.
1649 */
1650 if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
1651 rw_enter(&dn->dn_struct_rwlock, RW_READER);
1652 drop_struct_lock = TRUE;
1653 }
1654
1655 /*
1656 * We need to hold the dn_struct_rwlock to make this assertion,
1657 * because it protects dn_phys / dn_next_nlevels from changing.
1658 */
1659 ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) ||
1660 dn->dn_phys->dn_nlevels > db->db_level ||
1661 dn->dn_next_nlevels[txgoff] > db->db_level ||
1662 dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level ||
1663 dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level);
1664
1665 /*
1666 * If we are overwriting a dedup BP, then unless it is snapshotted,
1667 * when we get to syncing context we will need to decrement its
1668 * refcount in the DDT. Prefetch the relevant DDT block so that
1669 * syncing context won't have to wait for the i/o.
1670 */
1671 ddt_prefetch(os->os_spa, db->db_blkptr);
1672
1673 if (db->db_level == 0) {
1674 dnode_new_blkid(dn, db->db_blkid, tx, drop_struct_lock);
1675 ASSERT(dn->dn_maxblkid >= db->db_blkid);
1676 }
1677
1678 if (db->db_level+1 < dn->dn_nlevels) {
1679 dmu_buf_impl_t *parent = db->db_parent;
1680 dbuf_dirty_record_t *di;
1681 int parent_held = FALSE;
1682
1683 if (db->db_parent == NULL || db->db_parent == dn->dn_dbuf) {
1684 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1685
1686 parent = dbuf_hold_level(dn, db->db_level+1,
1687 db->db_blkid >> epbs, FTAG);
1688 ASSERT(parent != NULL);
1689 parent_held = TRUE;
1690 }
1691 if (drop_struct_lock)
1692 rw_exit(&dn->dn_struct_rwlock);
1693 ASSERT3U(db->db_level+1, ==, parent->db_level);
1694 di = dbuf_dirty(parent, tx);
1695 if (parent_held)
1696 dbuf_rele(parent, FTAG);
1697
1698 mutex_enter(&db->db_mtx);
1699 /*
1700 * Since we've dropped the mutex, it's possible that
1701 * dbuf_undirty() might have changed this out from under us.
1702 */
1703 if (db->db_last_dirty == dr ||
1704 dn->dn_object == DMU_META_DNODE_OBJECT) {
1705 mutex_enter(&di->dt.di.dr_mtx);
1706 ASSERT3U(di->dr_txg, ==, tx->tx_txg);
1707 ASSERT(!list_link_active(&dr->dr_dirty_node));
1708 list_insert_tail(&di->dt.di.dr_children, dr);
1709 mutex_exit(&di->dt.di.dr_mtx);
1710 dr->dr_parent = di;
1711 }
1712 mutex_exit(&db->db_mtx);
1713 } else {
1714 ASSERT(db->db_level+1 == dn->dn_nlevels);
1715 ASSERT(db->db_blkid < dn->dn_nblkptr);
1716 ASSERT(db->db_parent == NULL || db->db_parent == dn->dn_dbuf);
1717 mutex_enter(&dn->dn_mtx);
1718 ASSERT(!list_link_active(&dr->dr_dirty_node));
1719 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1720 mutex_exit(&dn->dn_mtx);
1721 if (drop_struct_lock)
1722 rw_exit(&dn->dn_struct_rwlock);
1723 }
1724
1725 dnode_setdirty(dn, tx);
1726 DB_DNODE_EXIT(db);
1727 return (dr);
1728 }
1729
1730 /*
1731 * Undirty a buffer in the transaction group referenced by the given
1732 * transaction. Return whether this evicted the dbuf.
1733 */
1734 static boolean_t
1735 dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1736 {
1737 dnode_t *dn;
1738 uint64_t txg = tx->tx_txg;
1739 dbuf_dirty_record_t *dr, **drp;
1740
1741 ASSERT(txg != 0);
1742
1743 /*
1744 * Due to our use of dn_nlevels below, this can only be called
1745 * in open context, unless we are operating on the MOS.
1746 * From syncing context, dn_nlevels may be different from the
1747 * dn_nlevels used when dbuf was dirtied.
1748 */
1749 ASSERT(db->db_objset ==
1750 dmu_objset_pool(db->db_objset)->dp_meta_objset ||
1751 txg != spa_syncing_txg(dmu_objset_spa(db->db_objset)));
1752 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1753 ASSERT0(db->db_level);
1754 ASSERT(MUTEX_HELD(&db->db_mtx));
1755
1756 /*
1757 * If this buffer is not dirty, we're done.
1758 */
1759 for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next)
1760 if (dr->dr_txg <= txg)
1761 break;
1762 if (dr == NULL || dr->dr_txg < txg)
1763 return (B_FALSE);
1764 ASSERT(dr->dr_txg == txg);
1765 ASSERT(dr->dr_dbuf == db);
1766
1767 DB_DNODE_ENTER(db);
1768 dn = DB_DNODE(db);
1769
1770 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1771
1772 ASSERT(db->db.db_size != 0);
1773
1774 dsl_pool_undirty_space(dmu_objset_pool(dn->dn_objset),
1775 dr->dr_accounted, txg);
1776
1777 *drp = dr->dr_next;
1778
1779 /*
1780 * Note that there are three places in dbuf_dirty()
1781 * where this dirty record may be put on a list.
1782 * Make sure to do a list_remove corresponding to
1783 * every one of those list_insert calls.
1784 */
1785 if (dr->dr_parent) {
1786 mutex_enter(&dr->dr_parent->dt.di.dr_mtx);
1787 list_remove(&dr->dr_parent->dt.di.dr_children, dr);
1788 mutex_exit(&dr->dr_parent->dt.di.dr_mtx);
1789 } else if (db->db_blkid == DMU_SPILL_BLKID ||
1790 db->db_level + 1 == dn->dn_nlevels) {
1791 ASSERT(db->db_blkptr == NULL || db->db_parent == dn->dn_dbuf);
1792 mutex_enter(&dn->dn_mtx);
1793 list_remove(&dn->dn_dirty_records[txg & TXG_MASK], dr);
1794 mutex_exit(&dn->dn_mtx);
1795 }
1796 DB_DNODE_EXIT(db);
1797
1798 if (db->db_state != DB_NOFILL) {
1799 dbuf_unoverride(dr);
1800
1801 ASSERT(db->db_buf != NULL);
1802 ASSERT(dr->dt.dl.dr_data != NULL);
1803 if (dr->dt.dl.dr_data != db->db_buf)
1804 arc_buf_destroy(dr->dt.dl.dr_data, db);
1805 }
1806
1807 kmem_free(dr, sizeof (dbuf_dirty_record_t));
1808
1809 ASSERT(db->db_dirtycnt > 0);
1810 db->db_dirtycnt -= 1;
1811
1812 if (refcount_remove(&db->db_holds, (void *)(uintptr_t)txg) == 0) {
1813 ASSERT(db->db_state == DB_NOFILL || arc_released(db->db_buf));
1814 dbuf_destroy(db);
1815 return (B_TRUE);
1816 }
1817
1818 return (B_FALSE);
1819 }
1820
1821 void
1822 dmu_buf_will_dirty(dmu_buf_t *db_fake, dmu_tx_t *tx)
1823 {
1824 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1825 int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH;
1826
1827 ASSERT(tx->tx_txg != 0);
1828 ASSERT(!refcount_is_zero(&db->db_holds));
1829
1830 /*
1831 * Quick check for dirtyness. For already dirty blocks, this
1832 * reduces runtime of this function by >90%, and overall performance
1833 * by 50% for some workloads (e.g. file deletion with indirect blocks
1834 * cached).
1835 */
1836 mutex_enter(&db->db_mtx);
1837 dbuf_dirty_record_t *dr;
1838 for (dr = db->db_last_dirty;
1839 dr != NULL && dr->dr_txg >= tx->tx_txg; dr = dr->dr_next) {
1840 /*
1841 * It's possible that it is already dirty but not cached,
1842 * because there are some calls to dbuf_dirty() that don't
1843 * go through dmu_buf_will_dirty().
1844 */
1845 if (dr->dr_txg == tx->tx_txg && db->db_state == DB_CACHED) {
1846 /* This dbuf is already dirty and cached. */
1847 dbuf_redirty(dr);
1848 mutex_exit(&db->db_mtx);
1849 return;
1850 }
1851 }
1852 mutex_exit(&db->db_mtx);
1853
1854 DB_DNODE_ENTER(db);
1855 if (RW_WRITE_HELD(&DB_DNODE(db)->dn_struct_rwlock))
1856 rf |= DB_RF_HAVESTRUCT;
1857 DB_DNODE_EXIT(db);
1858 (void) dbuf_read(db, NULL, rf);
1859 (void) dbuf_dirty(db, tx);
1860 }
1861
1862 void
1863 dmu_buf_will_not_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1864 {
1865 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1866
1867 db->db_state = DB_NOFILL;
1868
1869 dmu_buf_will_fill(db_fake, tx);
1870 }
1871
1872 void
1873 dmu_buf_will_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1874 {
1875 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1876
1877 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1878 ASSERT(tx->tx_txg != 0);
1879 ASSERT(db->db_level == 0);
1880 ASSERT(!refcount_is_zero(&db->db_holds));
1881
1882 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT ||
1883 dmu_tx_private_ok(tx));
1884
1885 dbuf_noread(db);
1886 (void) dbuf_dirty(db, tx);
1887 }
1888
1889 #pragma weak dmu_buf_fill_done = dbuf_fill_done
1890 /* ARGSUSED */
1891 void
1892 dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx)
1893 {
1894 mutex_enter(&db->db_mtx);
1895 DBUF_VERIFY(db);
1896
1897 if (db->db_state == DB_FILL) {
1898 if (db->db_level == 0 && db->db_freed_in_flight) {
1899 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1900 /* we were freed while filling */
1901 /* XXX dbuf_undirty? */
1902 bzero(db->db.db_data, db->db.db_size);
1903 db->db_freed_in_flight = FALSE;
1904 }
1905 db->db_state = DB_CACHED;
1906 cv_broadcast(&db->db_changed);
1907 }
1908 mutex_exit(&db->db_mtx);
1909 }
1910
1911 void
1912 dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
1913 bp_embedded_type_t etype, enum zio_compress comp,
1914 int uncompressed_size, int compressed_size, int byteorder,
1915 dmu_tx_t *tx)
1916 {
1917 dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf;
1918 struct dirty_leaf *dl;
1919 dmu_object_type_t type;
1920
1921 if (etype == BP_EMBEDDED_TYPE_DATA) {
1922 ASSERT(spa_feature_is_active(dmu_objset_spa(db->db_objset),
1923 SPA_FEATURE_EMBEDDED_DATA));
1924 }
1925
1926 DB_DNODE_ENTER(db);
1927 type = DB_DNODE(db)->dn_type;
1928 DB_DNODE_EXIT(db);
1929
1930 ASSERT0(db->db_level);
1931 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1932
1933 dmu_buf_will_not_fill(dbuf, tx);
1934
1935 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
1936 dl = &db->db_last_dirty->dt.dl;
1937 encode_embedded_bp_compressed(&dl->dr_overridden_by,
1938 data, comp, uncompressed_size, compressed_size);
1939 BPE_SET_ETYPE(&dl->dr_overridden_by, etype);
1940 BP_SET_TYPE(&dl->dr_overridden_by, type);
1941 BP_SET_LEVEL(&dl->dr_overridden_by, 0);
1942 BP_SET_BYTEORDER(&dl->dr_overridden_by, byteorder);
1943
1944 dl->dr_override_state = DR_OVERRIDDEN;
1945 dl->dr_overridden_by.blk_birth = db->db_last_dirty->dr_txg;
1946 }
1947
1948 /*
1949 * Directly assign a provided arc buf to a given dbuf if it's not referenced
1950 * by anybody except our caller. Otherwise copy arcbuf's contents to dbuf.
1951 */
1952 void
1953 dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx)
1954 {
1955 ASSERT(!refcount_is_zero(&db->db_holds));
1956 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
1957 ASSERT(db->db_level == 0);
1958 ASSERT3U(dbuf_is_metadata(db), ==, arc_is_metadata(buf));
1959 ASSERT(buf != NULL);
1960 ASSERT(arc_buf_lsize(buf) == db->db.db_size);
1961 ASSERT(tx->tx_txg != 0);
1962
1963 arc_return_buf(buf, db);
1964 ASSERT(arc_released(buf));
1965
1966 mutex_enter(&db->db_mtx);
1967
1968 while (db->db_state == DB_READ || db->db_state == DB_FILL)
1969 cv_wait(&db->db_changed, &db->db_mtx);
1970
1971 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED);
1972
1973 if (db->db_state == DB_CACHED &&
1974 refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) {
1975 mutex_exit(&db->db_mtx);
1976 (void) dbuf_dirty(db, tx);
1977 bcopy(buf->b_data, db->db.db_data, db->db.db_size);
1978 arc_buf_destroy(buf, db);
1979 xuio_stat_wbuf_copied();
1980 return;
1981 }
1982
1983 xuio_stat_wbuf_nocopy();
1984 if (db->db_state == DB_CACHED) {
1985 dbuf_dirty_record_t *dr = db->db_last_dirty;
1986
1987 ASSERT(db->db_buf != NULL);
1988 if (dr != NULL && dr->dr_txg == tx->tx_txg) {
1989 ASSERT(dr->dt.dl.dr_data == db->db_buf);
1990 if (!arc_released(db->db_buf)) {
1991 ASSERT(dr->dt.dl.dr_override_state ==
1992 DR_OVERRIDDEN);
1993 arc_release(db->db_buf, db);
1994 }
1995 dr->dt.dl.dr_data = buf;
1996 arc_buf_destroy(db->db_buf, db);
1997 } else if (dr == NULL || dr->dt.dl.dr_data != db->db_buf) {
1998 arc_release(db->db_buf, db);
1999 arc_buf_destroy(db->db_buf, db);
2000 }
2001 db->db_buf = NULL;
2002 }
2003 ASSERT(db->db_buf == NULL);
2004 dbuf_set_data(db, buf);
2005 db->db_state = DB_FILL;
2006 mutex_exit(&db->db_mtx);
2007 (void) dbuf_dirty(db, tx);
2008 dmu_buf_fill_done(&db->db, tx);
2009 }
2010
2011 void
2012 dbuf_destroy(dmu_buf_impl_t *db)
2013 {
2014 dnode_t *dn;
2015 dmu_buf_impl_t *parent = db->db_parent;
2016 dmu_buf_impl_t *dndb;
2017
2018 ASSERT(MUTEX_HELD(&db->db_mtx));
2019 ASSERT(refcount_is_zero(&db->db_holds));
2020
2021 if (db->db_buf != NULL) {
2022 arc_buf_destroy(db->db_buf, db);
2023 db->db_buf = NULL;
2024 }
2025
2026 if (db->db_blkid == DMU_BONUS_BLKID) {
2027 ASSERT(db->db.db_data != NULL);
2028 zio_buf_free(db->db.db_data, DN_MAX_BONUSLEN);
2029 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
2030 db->db_state = DB_UNCACHED;
2031 }
2032
2033 dbuf_clear_data(db);
2034
2035 if (multilist_link_active(&db->db_cache_link)) {
2036 multilist_remove(dbuf_cache, db);
2037 (void) refcount_remove_many(&dbuf_cache_size,
2038 db->db.db_size, db);
2039 }
2040
2041 ASSERT(db->db_state == DB_UNCACHED || db->db_state == DB_NOFILL);
2042 ASSERT(db->db_data_pending == NULL);
2043
2044 db->db_state = DB_EVICTING;
2045 db->db_blkptr = NULL;
2046
2047 /*
2048 * Now that db_state is DB_EVICTING, nobody else can find this via
2049 * the hash table. We can now drop db_mtx, which allows us to
2050 * acquire the dn_dbufs_mtx.
2051 */
2052 mutex_exit(&db->db_mtx);
2053
2054 DB_DNODE_ENTER(db);
2055 dn = DB_DNODE(db);
2056 dndb = dn->dn_dbuf;
2057 if (db->db_blkid != DMU_BONUS_BLKID) {
2058 boolean_t needlock = !MUTEX_HELD(&dn->dn_dbufs_mtx);
2059 if (needlock)
2060 mutex_enter(&dn->dn_dbufs_mtx);
2061 avl_remove(&dn->dn_dbufs, db);
2062 atomic_dec_32(&dn->dn_dbufs_count);
2063 membar_producer();
2064 DB_DNODE_EXIT(db);
2065 if (needlock)
2066 mutex_exit(&dn->dn_dbufs_mtx);
2067 /*
2068 * Decrementing the dbuf count means that the hold corresponding
2069 * to the removed dbuf is no longer discounted in dnode_move(),
2070 * so the dnode cannot be moved until after we release the hold.
2071 * The membar_producer() ensures visibility of the decremented
2072 * value in dnode_move(), since DB_DNODE_EXIT doesn't actually
2073 * release any lock.
2074 */
2075 dnode_rele(dn, db);
2076 db->db_dnode_handle = NULL;
2077
2078 dbuf_hash_remove(db);
2079 } else {
2080 DB_DNODE_EXIT(db);
2081 }
2082
2083 ASSERT(refcount_is_zero(&db->db_holds));
2084
2085 db->db_parent = NULL;
2086
2087 ASSERT(db->db_buf == NULL);
2088 ASSERT(db->db.db_data == NULL);
2089 ASSERT(db->db_hash_next == NULL);
2090 ASSERT(db->db_blkptr == NULL);
2091 ASSERT(db->db_data_pending == NULL);
2092 ASSERT(!multilist_link_active(&db->db_cache_link));
2093
2094 kmem_cache_free(dbuf_kmem_cache, db);
2095 arc_space_return(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
2096
2097 /*
2098 * If this dbuf is referenced from an indirect dbuf,
2099 * decrement the ref count on the indirect dbuf.
2100 */
2101 if (parent && parent != dndb)
2102 dbuf_rele(parent, db);
2103 }
2104
2105 /*
2106 * Note: While bpp will always be updated if the function returns success,
2107 * parentp will not be updated if the dnode does not have dn_dbuf filled in;
2108 * this happens when the dnode is the meta-dnode, or a userused or groupused
2109 * object.
2110 */
2111 static int
2112 dbuf_findbp(dnode_t *dn, int level, uint64_t blkid, int fail_sparse,
2113 dmu_buf_impl_t **parentp, blkptr_t **bpp)
2114 {
2115 *parentp = NULL;
2116 *bpp = NULL;
2117
2118 ASSERT(blkid != DMU_BONUS_BLKID);
2119
2120 if (blkid == DMU_SPILL_BLKID) {
2121 mutex_enter(&dn->dn_mtx);
2122 if (dn->dn_have_spill &&
2123 (dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR))
2124 *bpp = &dn->dn_phys->dn_spill;
2125 else
2126 *bpp = NULL;
2127 dbuf_add_ref(dn->dn_dbuf, NULL);
2128 *parentp = dn->dn_dbuf;
2129 mutex_exit(&dn->dn_mtx);
2130 return (0);
2131 }
2132
2133 int nlevels =
2134 (dn->dn_phys->dn_nlevels == 0) ? 1 : dn->dn_phys->dn_nlevels;
2135 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
2136
2137 ASSERT3U(level * epbs, <, 64);
2138 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
2139 /*
2140 * This assertion shouldn't trip as long as the max indirect block size
2141 * is less than 1M. The reason for this is that up to that point,
2142 * the number of levels required to address an entire object with blocks
2143 * of size SPA_MINBLOCKSIZE satisfies nlevels * epbs + 1 <= 64. In
2144 * other words, if N * epbs + 1 > 64, then if (N-1) * epbs + 1 > 55
2145 * (i.e. we can address the entire object), objects will all use at most
2146 * N-1 levels and the assertion won't overflow. However, once epbs is
2147 * 13, 4 * 13 + 1 = 53, but 5 * 13 + 1 = 66. Then, 4 levels will not be
2148 * enough to address an entire object, so objects will have 5 levels,
2149 * but then this assertion will overflow.
2150 *
2151 * All this is to say that if we ever increase DN_MAX_INDBLKSHIFT, we
2152 * need to redo this logic to handle overflows.
2153 */
2154 ASSERT(level >= nlevels ||
2155 ((nlevels - level - 1) * epbs) +
2156 highbit64(dn->dn_phys->dn_nblkptr) <= 64);
2157 if (level >= nlevels ||
2158 blkid >= ((uint64_t)dn->dn_phys->dn_nblkptr <<
2159 ((nlevels - level - 1) * epbs)) ||
2160 (fail_sparse &&
2161 blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))) {
2162 /* the buffer has no parent yet */
2163 return (SET_ERROR(ENOENT));
2164 } else if (level < nlevels-1) {
2165 /* this block is referenced from an indirect block */
2166 int err = dbuf_hold_impl(dn, level+1,
2167 blkid >> epbs, fail_sparse, FALSE, NULL, parentp);
2168 if (err)
2169 return (err);
2170 err = dbuf_read(*parentp, NULL,
2171 (DB_RF_HAVESTRUCT | DB_RF_NOPREFETCH | DB_RF_CANFAIL));
2172 if (err) {
2173 dbuf_rele(*parentp, NULL);
2174 *parentp = NULL;
2175 return (err);
2176 }
2177 *bpp = ((blkptr_t *)(*parentp)->db.db_data) +
2178 (blkid & ((1ULL << epbs) - 1));
2179 if (blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))
2180 ASSERT(BP_IS_HOLE(*bpp));
2181 return (0);
2182 } else {
2183 /* the block is referenced from the dnode */
2184 ASSERT3U(level, ==, nlevels-1);
2185 ASSERT(dn->dn_phys->dn_nblkptr == 0 ||
2186 blkid < dn->dn_phys->dn_nblkptr);
2187 if (dn->dn_dbuf) {
2188 dbuf_add_ref(dn->dn_dbuf, NULL);
2189 *parentp = dn->dn_dbuf;
2190 }
2191 *bpp = &dn->dn_phys->dn_blkptr[blkid];
2192 return (0);
2193 }
2194 }
2195
2196 static dmu_buf_impl_t *
2197 dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid,
2198 dmu_buf_impl_t *parent, blkptr_t *blkptr)
2199 {
2200 objset_t *os = dn->dn_objset;
2201 dmu_buf_impl_t *db, *odb;
2202
2203 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
2204 ASSERT(dn->dn_type != DMU_OT_NONE);
2205
2206 db = kmem_cache_alloc(dbuf_kmem_cache, KM_SLEEP);
2207
2208 db->db_objset = os;
2209 db->db.db_object = dn->dn_object;
2210 db->db_level = level;
2211 db->db_blkid = blkid;
2212 db->db_last_dirty = NULL;
2213 db->db_dirtycnt = 0;
2214 db->db_dnode_handle = dn->dn_handle;
2215 db->db_parent = parent;
2216 db->db_blkptr = blkptr;
2217
2218 db->db_user = NULL;
2219 db->db_user_immediate_evict = FALSE;
2220 db->db_freed_in_flight = FALSE;
2221 db->db_pending_evict = FALSE;
2222
2223 if (blkid == DMU_BONUS_BLKID) {
2224 ASSERT3P(parent, ==, dn->dn_dbuf);
2225 db->db.db_size = DN_MAX_BONUSLEN -
2226 (dn->dn_nblkptr-1) * sizeof (blkptr_t);
2227 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
2228 db->db.db_offset = DMU_BONUS_BLKID;
2229 db->db_state = DB_UNCACHED;
2230 /* the bonus dbuf is not placed in the hash table */
2231 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
2232 return (db);
2233 } else if (blkid == DMU_SPILL_BLKID) {
2234 db->db.db_size = (blkptr != NULL) ?
2235 BP_GET_LSIZE(blkptr) : SPA_MINBLOCKSIZE;
2236 db->db.db_offset = 0;
2237 } else {
2238 int blocksize =
2239 db->db_level ? 1 << dn->dn_indblkshift : dn->dn_datablksz;
2240 db->db.db_size = blocksize;
2241 db->db.db_offset = db->db_blkid * blocksize;
2242 }
2243
2244 /*
2245 * Hold the dn_dbufs_mtx while we get the new dbuf
2246 * in the hash table *and* added to the dbufs list.
2247 * This prevents a possible deadlock with someone
2248 * trying to look up this dbuf before its added to the
2249 * dn_dbufs list.
2250 */
2251 mutex_enter(&dn->dn_dbufs_mtx);
2252 db->db_state = DB_EVICTING;
2253 if ((odb = dbuf_hash_insert(db)) != NULL) {
2254 /* someone else inserted it first */
2255 kmem_cache_free(dbuf_kmem_cache, db);
2256 mutex_exit(&dn->dn_dbufs_mtx);
2257 return (odb);
2258 }
2259 avl_add(&dn->dn_dbufs, db);
2260
2261 db->db_state = DB_UNCACHED;
2262 mutex_exit(&dn->dn_dbufs_mtx);
2263 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);
2264
2265 if (parent && parent != dn->dn_dbuf)
2266 dbuf_add_ref(parent, db);
2267
2268 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
2269 refcount_count(&dn->dn_holds) > 0);
2270 (void) refcount_add(&dn->dn_holds, db);
2271 atomic_inc_32(&dn->dn_dbufs_count);
2272
2273 dprintf_dbuf(db, "db=%p\n", db);
2274
2275 return (db);
2276 }
2277
2278 typedef struct dbuf_prefetch_arg {
2279 spa_t *dpa_spa; /* The spa to issue the prefetch in. */
2280 zbookmark_phys_t dpa_zb; /* The target block to prefetch. */
2281 int dpa_epbs; /* Entries (blkptr_t's) Per Block Shift. */
2282 int dpa_curlevel; /* The current level that we're reading */
2283 dnode_t *dpa_dnode; /* The dnode associated with the prefetch */
2284 zio_priority_t dpa_prio; /* The priority I/Os should be issued at. */
2285 zio_t *dpa_zio; /* The parent zio_t for all prefetches. */
2286 arc_flags_t dpa_aflags; /* Flags to pass to the final prefetch. */
2287 } dbuf_prefetch_arg_t;
2288
2289 /*
2290 * Actually issue the prefetch read for the block given.
2291 */
2292 static void
2293 dbuf_issue_final_prefetch(dbuf_prefetch_arg_t *dpa, blkptr_t *bp)
2294 {
2295 if (BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp))
2296 return;
2297
2298 arc_flags_t aflags =
2299 dpa->dpa_aflags | ARC_FLAG_NOWAIT | ARC_FLAG_PREFETCH;
2300
2301 ASSERT3U(dpa->dpa_curlevel, ==, BP_GET_LEVEL(bp));
2302 ASSERT3U(dpa->dpa_curlevel, ==, dpa->dpa_zb.zb_level);
2303 ASSERT(dpa->dpa_zio != NULL);
2304 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa, bp, NULL, NULL,
2305 dpa->dpa_prio, ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
2306 &aflags, &dpa->dpa_zb);
2307 }
2308
2309 /*
2310 * Called when an indirect block above our prefetch target is read in. This
2311 * will either read in the next indirect block down the tree or issue the actual
2312 * prefetch if the next block down is our target.
2313 */
2314 static void
2315 dbuf_prefetch_indirect_done(zio_t *zio, arc_buf_t *abuf, void *private)
2316 {
2317 dbuf_prefetch_arg_t *dpa = private;
2318
2319 ASSERT3S(dpa->dpa_zb.zb_level, <, dpa->dpa_curlevel);
2320 ASSERT3S(dpa->dpa_curlevel, >, 0);
2321
2322 /*
2323 * The dpa_dnode is only valid if we are called with a NULL
2324 * zio. This indicates that the arc_read() returned without
2325 * first calling zio_read() to issue a physical read. Once
2326 * a physical read is made the dpa_dnode must be invalidated
2327 * as the locks guarding it may have been dropped. If the
2328 * dpa_dnode is still valid, then we want to add it to the dbuf
2329 * cache. To do so, we must hold the dbuf associated with the block
2330 * we just prefetched, read its contents so that we associate it
2331 * with an arc_buf_t, and then release it.
2332 */
2333 if (zio != NULL) {
2334 ASSERT3S(BP_GET_LEVEL(zio->io_bp), ==, dpa->dpa_curlevel);
2335 if (zio->io_flags & ZIO_FLAG_RAW) {
2336 ASSERT3U(BP_GET_PSIZE(zio->io_bp), ==, zio->io_size);
2337 } else {
2338 ASSERT3U(BP_GET_LSIZE(zio->io_bp), ==, zio->io_size);
2339 }
2340 ASSERT3P(zio->io_spa, ==, dpa->dpa_spa);
2341
2342 dpa->dpa_dnode = NULL;
2343 } else if (dpa->dpa_dnode != NULL) {
2344 uint64_t curblkid = dpa->dpa_zb.zb_blkid >>
2345 (dpa->dpa_epbs * (dpa->dpa_curlevel -
2346 dpa->dpa_zb.zb_level));
2347 dmu_buf_impl_t *db = dbuf_hold_level(dpa->dpa_dnode,
2348 dpa->dpa_curlevel, curblkid, FTAG);
2349 (void) dbuf_read(db, NULL,
2350 DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH | DB_RF_HAVESTRUCT);
2351 dbuf_rele(db, FTAG);
2352 }
2353
2354 dpa->dpa_curlevel--;
2355
2356 uint64_t nextblkid = dpa->dpa_zb.zb_blkid >>
2357 (dpa->dpa_epbs * (dpa->dpa_curlevel - dpa->dpa_zb.zb_level));
2358 blkptr_t *bp = ((blkptr_t *)abuf->b_data) +
2359 P2PHASE(nextblkid, 1ULL << dpa->dpa_epbs);
2360 if (BP_IS_HOLE(bp) || (zio != NULL && zio->io_error != 0)) {
2361 kmem_free(dpa, sizeof (*dpa));
2362 } else if (dpa->dpa_curlevel == dpa->dpa_zb.zb_level) {
2363 ASSERT3U(nextblkid, ==, dpa->dpa_zb.zb_blkid);
2364 dbuf_issue_final_prefetch(dpa, bp);
2365 kmem_free(dpa, sizeof (*dpa));
2366 } else {
2367 arc_flags_t iter_aflags = ARC_FLAG_NOWAIT;
2368 zbookmark_phys_t zb;
2369
2370 /* flag if L2ARC eligible, l2arc_noprefetch then decides */
2371 if (dpa->dpa_aflags & ARC_FLAG_L2CACHE)
2372 iter_aflags |= ARC_FLAG_L2CACHE;
2373
2374 ASSERT3U(dpa->dpa_curlevel, ==, BP_GET_LEVEL(bp));
2375
2376 SET_BOOKMARK(&zb, dpa->dpa_zb.zb_objset,
2377 dpa->dpa_zb.zb_object, dpa->dpa_curlevel, nextblkid);
2378
2379 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa,
2380 bp, dbuf_prefetch_indirect_done, dpa, dpa->dpa_prio,
2381 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
2382 &iter_aflags, &zb);
2383 }
2384
2385 arc_buf_destroy(abuf, private);
2386 }
2387
2388 /*
2389 * Issue prefetch reads for the given block on the given level. If the indirect
2390 * blocks above that block are not in memory, we will read them in
2391 * asynchronously. As a result, this call never blocks waiting for a read to
2392 * complete.
2393 */
2394 void
2395 dbuf_prefetch(dnode_t *dn, int64_t level, uint64_t blkid, zio_priority_t prio,
2396 arc_flags_t aflags)
2397 {
2398 blkptr_t bp;
2399 int epbs, nlevels, curlevel;
2400 uint64_t curblkid;
2401
2402 ASSERT(blkid != DMU_BONUS_BLKID);
2403 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
2404
2405 if (blkid > dn->dn_maxblkid)
2406 return;
2407
2408 if (dnode_block_freed(dn, blkid))
2409 return;
2410
2411 /*
2412 * This dnode hasn't been written to disk yet, so there's nothing to
2413 * prefetch.
2414 */
2415 nlevels = dn->dn_phys->dn_nlevels;
2416 if (level >= nlevels || dn->dn_phys->dn_nblkptr == 0)
2417 return;
2418
2419 epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2420 if (dn->dn_phys->dn_maxblkid < blkid << (epbs * level))
2421 return;
2422
2423 dmu_buf_impl_t *db = dbuf_find(dn->dn_objset, dn->dn_object,
2424 level, blkid);
2425 if (db != NULL) {
2426 mutex_exit(&db->db_mtx);
2427 /*
2428 * This dbuf already exists. It is either CACHED, or
2429 * (we assume) about to be read or filled.
2430 */
2431 return;
2432 }
2433
2434 /*
2435 * Find the closest ancestor (indirect block) of the target block
2436 * that is present in the cache. In this indirect block, we will
2437 * find the bp that is at curlevel, curblkid.
2438 */
2439 curlevel = level;
2440 curblkid = blkid;
2441 while (curlevel < nlevels - 1) {
2442 int parent_level = curlevel + 1;
2443 uint64_t parent_blkid = curblkid >> epbs;
2444 dmu_buf_impl_t *db;
2445
2446 if (dbuf_hold_impl(dn, parent_level, parent_blkid,
2447 FALSE, TRUE, FTAG, &db) == 0) {
2448 blkptr_t *bpp = db->db_buf->b_data;
2449 bp = bpp[P2PHASE(curblkid, 1 << epbs)];
2450 dbuf_rele(db, FTAG);
2451 break;
2452 }
2453
2454 curlevel = parent_level;
2455 curblkid = parent_blkid;
2456 }
2457
2458 if (curlevel == nlevels - 1) {
2459 /* No cached indirect blocks found. */
2460 ASSERT3U(curblkid, <, dn->dn_phys->dn_nblkptr);
2461 bp = dn->dn_phys->dn_blkptr[curblkid];
2462 }
2463 if (BP_IS_HOLE(&bp))
2464 return;
2465
2466 ASSERT3U(curlevel, ==, BP_GET_LEVEL(&bp));
2467
2468 zio_t *pio = zio_root(dmu_objset_spa(dn->dn_objset), NULL, NULL,
2469 ZIO_FLAG_CANFAIL);
2470
2471 dbuf_prefetch_arg_t *dpa = kmem_zalloc(sizeof (*dpa), KM_SLEEP);
2472 dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset;
2473 SET_BOOKMARK(&dpa->dpa_zb, ds != NULL ? ds->ds_object : DMU_META_OBJSET,
2474 dn->dn_object, level, blkid);
2475 dpa->dpa_curlevel = curlevel;
2476 dpa->dpa_prio = prio;
2477 dpa->dpa_aflags = aflags;
2478 dpa->dpa_spa = dn->dn_objset->os_spa;
2479 dpa->dpa_dnode = dn;
2480 dpa->dpa_epbs = epbs;
2481 dpa->dpa_zio = pio;
2482
2483 /* flag if L2ARC eligible, l2arc_noprefetch then decides */
2484 if (DNODE_LEVEL_IS_L2CACHEABLE(dn, level))
2485 dpa->dpa_aflags |= ARC_FLAG_L2CACHE;
2486
2487 /*
2488 * If we have the indirect just above us, no need to do the asynchronous
2489 * prefetch chain; we'll just run the last step ourselves. If we're at
2490 * a higher level, though, we want to issue the prefetches for all the
2491 * indirect blocks asynchronously, so we can go on with whatever we were
2492 * doing.
2493 */
2494 if (curlevel == level) {
2495 ASSERT3U(curblkid, ==, blkid);
2496 dbuf_issue_final_prefetch(dpa, &bp);
2497 kmem_free(dpa, sizeof (*dpa));
2498 } else {
2499 arc_flags_t iter_aflags = ARC_FLAG_NOWAIT;
2500 zbookmark_phys_t zb;
2501
2502 /* flag if L2ARC eligible, l2arc_noprefetch then decides */
2503 if (DNODE_LEVEL_IS_L2CACHEABLE(dn, level))
2504 iter_aflags |= ARC_FLAG_L2CACHE;
2505
2506 SET_BOOKMARK(&zb, ds != NULL ? ds->ds_object : DMU_META_OBJSET,
2507 dn->dn_object, curlevel, curblkid);
2508 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa,
2509 &bp, dbuf_prefetch_indirect_done, dpa, prio,
2510 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
2511 &iter_aflags, &zb);
2512 }
2513 /*
2514 * We use pio here instead of dpa_zio since it's possible that
2515 * dpa may have already been freed.
2516 */
2517 zio_nowait(pio);
2518 }
2519
2520 /*
2521 * Returns with db_holds incremented, and db_mtx not held.
2522 * Note: dn_struct_rwlock must be held.
2523 */
2524 int
2525 dbuf_hold_impl(dnode_t *dn, uint8_t level, uint64_t blkid,
2526 boolean_t fail_sparse, boolean_t fail_uncached,
2527 void *tag, dmu_buf_impl_t **dbp)
2528 {
2529 dmu_buf_impl_t *db, *parent = NULL;
2530
2531 ASSERT(blkid != DMU_BONUS_BLKID);
2532 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
2533 ASSERT3U(dn->dn_nlevels, >, level);
2534
2535 *dbp = NULL;
2536 top:
2537 /* dbuf_find() returns with db_mtx held */
2538 db = dbuf_find(dn->dn_objset, dn->dn_object, level, blkid);
2539
2540 if (db == NULL) {
2541 blkptr_t *bp = NULL;
2542 int err;
2543
2544 if (fail_uncached)
2545 return (SET_ERROR(ENOENT));
2546
2547 ASSERT3P(parent, ==, NULL);
2548 err = dbuf_findbp(dn, level, blkid, fail_sparse, &parent, &bp);
2549 if (fail_sparse) {
2550 if (err == 0 && bp && BP_IS_HOLE(bp))
2551 err = SET_ERROR(ENOENT);
2552 if (err) {
2553 if (parent)
2554 dbuf_rele(parent, NULL);
2555 return (err);
2556 }
2557 }
2558 if (err && err != ENOENT)
2559 return (err);
2560 db = dbuf_create(dn, level, blkid, parent, bp);
2561 }
2562
2563 if (fail_uncached && db->db_state != DB_CACHED) {
2564 mutex_exit(&db->db_mtx);
2565 return (SET_ERROR(ENOENT));
2566 }
2567
2568 if (db->db_buf != NULL)
2569 ASSERT3P(db->db.db_data, ==, db->db_buf->b_data);
2570
2571 ASSERT(db->db_buf == NULL || arc_referenced(db->db_buf));
2572
2573 /*
2574 * If this buffer is currently syncing out, and we are are
2575 * still referencing it from db_data, we need to make a copy
2576 * of it in case we decide we want to dirty it again in this txg.
2577 */
2578 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
2579 dn->dn_object != DMU_META_DNODE_OBJECT &&
2580 db->db_state == DB_CACHED && db->db_data_pending) {
2581 dbuf_dirty_record_t *dr = db->db_data_pending;
2582
2583 if (dr->dt.dl.dr_data == db->db_buf) {
2584 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
2585
2586 dbuf_set_data(db,
2587 arc_alloc_buf(dn->dn_objset->os_spa, db, type,
2588 db->db.db_size));
2589 bcopy(dr->dt.dl.dr_data->b_data, db->db.db_data,
2590 db->db.db_size);
2591 }
2592 }
2593
2594 if (multilist_link_active(&db->db_cache_link)) {
2595 ASSERT(refcount_is_zero(&db->db_holds));
2596 multilist_remove(dbuf_cache, db);
2597 (void) refcount_remove_many(&dbuf_cache_size,
2598 db->db.db_size, db);
2599 }
2600 (void) refcount_add(&db->db_holds, tag);
2601 DBUF_VERIFY(db);
2602 mutex_exit(&db->db_mtx);
2603
2604 /* NOTE: we can't rele the parent until after we drop the db_mtx */
2605 if (parent)
2606 dbuf_rele(parent, NULL);
2607
2608 ASSERT3P(DB_DNODE(db), ==, dn);
2609 ASSERT3U(db->db_blkid, ==, blkid);
2610 ASSERT3U(db->db_level, ==, level);
2611 *dbp = db;
2612
2613 return (0);
2614 }
2615
2616 dmu_buf_impl_t *
2617 dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag)
2618 {
2619 return (dbuf_hold_level(dn, 0, blkid, tag));
2620 }
2621
2622 dmu_buf_impl_t *
2623 dbuf_hold_level(dnode_t *dn, int level, uint64_t blkid, void *tag)
2624 {
2625 dmu_buf_impl_t *db;
2626 int err = dbuf_hold_impl(dn, level, blkid, FALSE, FALSE, tag, &db);
2627 return (err ? NULL : db);
2628 }
2629
2630 void
2631 dbuf_create_bonus(dnode_t *dn)
2632 {
2633 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
2634
2635 ASSERT(dn->dn_bonus == NULL);
2636 dn->dn_bonus = dbuf_create(dn, 0, DMU_BONUS_BLKID, dn->dn_dbuf, NULL);
2637 }
2638
2639 int
2640 dbuf_spill_set_blksz(dmu_buf_t *db_fake, uint64_t blksz, dmu_tx_t *tx)
2641 {
2642 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2643 dnode_t *dn;
2644
2645 if (db->db_blkid != DMU_SPILL_BLKID)
2646 return (SET_ERROR(ENOTSUP));
2647 if (blksz == 0)
2648 blksz = SPA_MINBLOCKSIZE;
2649 ASSERT3U(blksz, <=, spa_maxblocksize(dmu_objset_spa(db->db_objset)));
2650 blksz = P2ROUNDUP(blksz, SPA_MINBLOCKSIZE);
2651
2652 DB_DNODE_ENTER(db);
2653 dn = DB_DNODE(db);
2654 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
2655 dbuf_new_size(db, blksz, tx);
2656 rw_exit(&dn->dn_struct_rwlock);
2657 DB_DNODE_EXIT(db);
2658
2659 return (0);
2660 }
2661
2662 void
2663 dbuf_rm_spill(dnode_t *dn, dmu_tx_t *tx)
2664 {
2665 dbuf_free_range(dn, DMU_SPILL_BLKID, DMU_SPILL_BLKID, tx);
2666 }
2667
2668 #pragma weak dmu_buf_add_ref = dbuf_add_ref
2669 void
2670 dbuf_add_ref(dmu_buf_impl_t *db, void *tag)
2671 {
2672 int64_t holds = refcount_add(&db->db_holds, tag);
2673 ASSERT3S(holds, >, 1);
2674 }
2675
2676 #pragma weak dmu_buf_try_add_ref = dbuf_try_add_ref
2677 boolean_t
2678 dbuf_try_add_ref(dmu_buf_t *db_fake, objset_t *os, uint64_t obj, uint64_t blkid,
2679 void *tag)
2680 {
2681 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2682 dmu_buf_impl_t *found_db;
2683 boolean_t result = B_FALSE;
2684
2685 if (db->db_blkid == DMU_BONUS_BLKID)
2686 found_db = dbuf_find_bonus(os, obj);
2687 else
2688 found_db = dbuf_find(os, obj, 0, blkid);
2689
2690 if (found_db != NULL) {
2691 if (db == found_db && dbuf_refcount(db) > db->db_dirtycnt) {
2692 (void) refcount_add(&db->db_holds, tag);
2693 result = B_TRUE;
2694 }
2695 mutex_exit(&db->db_mtx);
2696 }
2697 return (result);
2698 }
2699
2700 /*
2701 * If you call dbuf_rele() you had better not be referencing the dnode handle
2702 * unless you have some other direct or indirect hold on the dnode. (An indirect
2703 * hold is a hold on one of the dnode's dbufs, including the bonus buffer.)
2704 * Without that, the dbuf_rele() could lead to a dnode_rele() followed by the
2705 * dnode's parent dbuf evicting its dnode handles.
2706 */
2707 void
2708 dbuf_rele(dmu_buf_impl_t *db, void *tag)
2709 {
2710 mutex_enter(&db->db_mtx);
2711 dbuf_rele_and_unlock(db, tag);
2712 }
2713
2714 void
2715 dmu_buf_rele(dmu_buf_t *db, void *tag)
2716 {
2717 dbuf_rele((dmu_buf_impl_t *)db, tag);
2718 }
2719
2720 /*
2721 * dbuf_rele() for an already-locked dbuf. This is necessary to allow
2722 * db_dirtycnt and db_holds to be updated atomically.
2723 */
2724 void
2725 dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag)
2726 {
2727 int64_t holds;
2728
2729 ASSERT(MUTEX_HELD(&db->db_mtx));
2730 DBUF_VERIFY(db);
2731
2732 /*
2733 * Remove the reference to the dbuf before removing its hold on the
2734 * dnode so we can guarantee in dnode_move() that a referenced bonus
2735 * buffer has a corresponding dnode hold.
2736 */
2737 holds = refcount_remove(&db->db_holds, tag);
2738 ASSERT(holds >= 0);
2739
2740 /*
2741 * We can't freeze indirects if there is a possibility that they
2742 * may be modified in the current syncing context.
2743 */
2744 if (db->db_buf != NULL &&
2745 holds == (db->db_level == 0 ? db->db_dirtycnt : 0)) {
2746 arc_buf_freeze(db->db_buf);
2747 }
2748
2749 if (holds == db->db_dirtycnt &&
2750 db->db_level == 0 && db->db_user_immediate_evict)
2751 dbuf_evict_user(db);
2752
2753 if (holds == 0) {
2754 if (db->db_blkid == DMU_BONUS_BLKID) {
2755 dnode_t *dn;
2756 boolean_t evict_dbuf = db->db_pending_evict;
2757
2758 /*
2759 * If the dnode moves here, we cannot cross this
2760 * barrier until the move completes.
2761 */
2762 DB_DNODE_ENTER(db);
2763
2764 dn = DB_DNODE(db);
2765 atomic_dec_32(&dn->dn_dbufs_count);
2766
2767 /*
2768 * Decrementing the dbuf count means that the bonus
2769 * buffer's dnode hold is no longer discounted in
2770 * dnode_move(). The dnode cannot move until after
2771 * the dnode_rele() below.
2772 */
2773 DB_DNODE_EXIT(db);
2774
2775 /*
2776 * Do not reference db after its lock is dropped.
2777 * Another thread may evict it.
2778 */
2779 mutex_exit(&db->db_mtx);
2780
2781 if (evict_dbuf)
2782 dnode_evict_bonus(dn);
2783
2784 dnode_rele(dn, db);
2785 } else if (db->db_buf == NULL) {
2786 /*
2787 * This is a special case: we never associated this
2788 * dbuf with any data allocated from the ARC.
2789 */
2790 ASSERT(db->db_state == DB_UNCACHED ||
2791 db->db_state == DB_NOFILL);
2792 dbuf_destroy(db);
2793 } else if (arc_released(db->db_buf)) {
2794 /*
2795 * This dbuf has anonymous data associated with it.
2796 */
2797 dbuf_destroy(db);
2798 } else {
2799 boolean_t do_arc_evict = B_FALSE;
2800 blkptr_t bp;
2801 spa_t *spa = dmu_objset_spa(db->db_objset);
2802
2803 if (!DBUF_IS_CACHEABLE(db) &&
2804 db->db_blkptr != NULL &&
2805 !BP_IS_HOLE(db->db_blkptr) &&
2806 !BP_IS_EMBEDDED(db->db_blkptr)) {
2807 do_arc_evict = B_TRUE;
2808 bp = *db->db_blkptr;
2809 }
2810
2811 if (!DBUF_IS_CACHEABLE(db) ||
2812 db->db_pending_evict) {
2813 dbuf_destroy(db);
2814 } else if (!multilist_link_active(&db->db_cache_link)) {
2815 multilist_insert(dbuf_cache, db);
2816 (void) refcount_add_many(&dbuf_cache_size,
2817 db->db.db_size, db);
2818 mutex_exit(&db->db_mtx);
2819
2820 dbuf_evict_notify();
2821 }
2822
2823 if (do_arc_evict)
2824 arc_freed(spa, &bp);
2825 }
2826 } else {
2827 mutex_exit(&db->db_mtx);
2828 }
2829
2830 }
2831
2832 #pragma weak dmu_buf_refcount = dbuf_refcount
2833 uint64_t
2834 dbuf_refcount(dmu_buf_impl_t *db)
2835 {
2836 return (refcount_count(&db->db_holds));
2837 }
2838
2839 void *
2840 dmu_buf_replace_user(dmu_buf_t *db_fake, dmu_buf_user_t *old_user,
2841 dmu_buf_user_t *new_user)
2842 {
2843 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2844
2845 mutex_enter(&db->db_mtx);
2846 dbuf_verify_user(db, DBVU_NOT_EVICTING);
2847 if (db->db_user == old_user)
2848 db->db_user = new_user;
2849 else
2850 old_user = db->db_user;
2851 dbuf_verify_user(db, DBVU_NOT_EVICTING);
2852 mutex_exit(&db->db_mtx);
2853
2854 return (old_user);
2855 }
2856
2857 void *
2858 dmu_buf_set_user(dmu_buf_t *db_fake, dmu_buf_user_t *user)
2859 {
2860 return (dmu_buf_replace_user(db_fake, NULL, user));
2861 }
2862
2863 void *
2864 dmu_buf_set_user_ie(dmu_buf_t *db_fake, dmu_buf_user_t *user)
2865 {
2866 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2867
2868 db->db_user_immediate_evict = TRUE;
2869 return (dmu_buf_set_user(db_fake, user));
2870 }
2871
2872 void *
2873 dmu_buf_remove_user(dmu_buf_t *db_fake, dmu_buf_user_t *user)
2874 {
2875 return (dmu_buf_replace_user(db_fake, user, NULL));
2876 }
2877
2878 void *
2879 dmu_buf_get_user(dmu_buf_t *db_fake)
2880 {
2881 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2882
2883 dbuf_verify_user(db, DBVU_NOT_EVICTING);
2884 return (db->db_user);
2885 }
2886
2887 void
2888 dmu_buf_user_evict_wait()
2889 {
2890 taskq_wait(dbu_evict_taskq);
2891 }
2892
2893 blkptr_t *
2894 dmu_buf_get_blkptr(dmu_buf_t *db)
2895 {
2896 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
2897 return (dbi->db_blkptr);
2898 }
2899
2900 objset_t *
2901 dmu_buf_get_objset(dmu_buf_t *db)
2902 {
2903 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
2904 return (dbi->db_objset);
2905 }
2906
2907 dnode_t *
2908 dmu_buf_dnode_enter(dmu_buf_t *db)
2909 {
2910 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
2911 DB_DNODE_ENTER(dbi);
2912 return (DB_DNODE(dbi));
2913 }
2914
2915 void
2916 dmu_buf_dnode_exit(dmu_buf_t *db)
2917 {
2918 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
2919 DB_DNODE_EXIT(dbi);
2920 }
2921
2922 static void
2923 dbuf_check_blkptr(dnode_t *dn, dmu_buf_impl_t *db)
2924 {
2925 /* ASSERT(dmu_tx_is_syncing(tx) */
2926 ASSERT(MUTEX_HELD(&db->db_mtx));
2927
2928 if (db->db_blkptr != NULL)
2929 return;
2930
2931 if (db->db_blkid == DMU_SPILL_BLKID) {
2932 db->db_blkptr = &dn->dn_phys->dn_spill;
2933 BP_ZERO(db->db_blkptr);
2934 return;
2935 }
2936 if (db->db_level == dn->dn_phys->dn_nlevels-1) {
2937 /*
2938 * This buffer was allocated at a time when there was
2939 * no available blkptrs from the dnode, or it was
2940 * inappropriate to hook it in (i.e., nlevels mis-match).
2941 */
2942 ASSERT(db->db_blkid < dn->dn_phys->dn_nblkptr);
2943 ASSERT(db->db_parent == NULL);
2944 db->db_parent = dn->dn_dbuf;
2945 db->db_blkptr = &dn->dn_phys->dn_blkptr[db->db_blkid];
2946 DBUF_VERIFY(db);
2947 } else {
2948 dmu_buf_impl_t *parent = db->db_parent;
2949 int epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2950
2951 ASSERT(dn->dn_phys->dn_nlevels > 1);
2952 if (parent == NULL) {
2953 mutex_exit(&db->db_mtx);
2954 rw_enter(&dn->dn_struct_rwlock, RW_READER);
2955 parent = dbuf_hold_level(dn, db->db_level + 1,
2956 db->db_blkid >> epbs, db);
2957 rw_exit(&dn->dn_struct_rwlock);
2958 mutex_enter(&db->db_mtx);
2959 db->db_parent = parent;
2960 }
2961 db->db_blkptr = (blkptr_t *)parent->db.db_data +
2962 (db->db_blkid & ((1ULL << epbs) - 1));
2963 DBUF_VERIFY(db);
2964 }
2965 }
2966
2967 static void
2968 dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
2969 {
2970 dmu_buf_impl_t *db = dr->dr_dbuf;
2971 dnode_t *dn;
2972 zio_t *zio;
2973
2974 ASSERT(dmu_tx_is_syncing(tx));
2975
2976 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
2977
2978 mutex_enter(&db->db_mtx);
2979
2980 ASSERT(db->db_level > 0);
2981 DBUF_VERIFY(db);
2982
2983 /* Read the block if it hasn't been read yet. */
2984 if (db->db_buf == NULL) {
2985 mutex_exit(&db->db_mtx);
2986 (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED);
2987 mutex_enter(&db->db_mtx);
2988 }
2989 ASSERT3U(db->db_state, ==, DB_CACHED);
2990 ASSERT(db->db_buf != NULL);
2991
2992 DB_DNODE_ENTER(db);
2993 dn = DB_DNODE(db);
2994 /* Indirect block size must match what the dnode thinks it is. */
2995 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2996 dbuf_check_blkptr(dn, db);
2997 DB_DNODE_EXIT(db);
2998
2999 /* Provide the pending dirty record to child dbufs */
3000 db->db_data_pending = dr;
3001
3002 mutex_exit(&db->db_mtx);
3003
3004 dbuf_write(dr, db->db_buf, tx);
3005
3006 zio = dr->dr_zio;
3007 mutex_enter(&dr->dt.di.dr_mtx);
3008 dbuf_sync_list(&dr->dt.di.dr_children, db->db_level - 1, tx);
3009 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
3010 mutex_exit(&dr->dt.di.dr_mtx);
3011 zio_nowait(zio);
3012 }
3013
3014 static void
3015 dbuf_sync_leaf(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
3016 {
3017 arc_buf_t **datap = &dr->dt.dl.dr_data;
3018 dmu_buf_impl_t *db = dr->dr_dbuf;
3019 dnode_t *dn;
3020 objset_t *os;
3021 uint64_t txg = tx->tx_txg;
3022
3023 ASSERT(dmu_tx_is_syncing(tx));
3024
3025 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
3026
3027 mutex_enter(&db->db_mtx);
3028 /*
3029 * To be synced, we must be dirtied. But we
3030 * might have been freed after the dirty.
3031 */
3032 if (db->db_state == DB_UNCACHED) {
3033 /* This buffer has been freed since it was dirtied */
3034 ASSERT(db->db.db_data == NULL);
3035 } else if (db->db_state == DB_FILL) {
3036 /* This buffer was freed and is now being re-filled */
3037 ASSERT(db->db.db_data != dr->dt.dl.dr_data);
3038 } else {
3039 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_NOFILL);
3040 }
3041 DBUF_VERIFY(db);
3042
3043 DB_DNODE_ENTER(db);
3044 dn = DB_DNODE(db);
3045
3046 if (db->db_blkid == DMU_SPILL_BLKID) {
3047 mutex_enter(&dn->dn_mtx);
3048 dn->dn_phys->dn_flags |= DNODE_FLAG_SPILL_BLKPTR;
3049 mutex_exit(&dn->dn_mtx);
3050 }
3051
3052 /*
3053 * If this is a bonus buffer, simply copy the bonus data into the
3054 * dnode. It will be written out when the dnode is synced (and it
3055 * will be synced, since it must have been dirty for dbuf_sync to
3056 * be called).
3057 */
3058 if (db->db_blkid == DMU_BONUS_BLKID) {
3059 dbuf_dirty_record_t **drp;
3060
3061 ASSERT(*datap != NULL);
3062 ASSERT0(db->db_level);
3063 ASSERT3U(dn->dn_phys->dn_bonuslen, <=, DN_MAX_BONUSLEN);
3064 bcopy(*datap, DN_BONUS(dn->dn_phys), dn->dn_phys->dn_bonuslen);
3065 DB_DNODE_EXIT(db);
3066
3067 if (*datap != db->db.db_data) {
3068 zio_buf_free(*datap, DN_MAX_BONUSLEN);
3069 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
3070 }
3071 db->db_data_pending = NULL;
3072 drp = &db->db_last_dirty;
3073 while (*drp != dr)
3074 drp = &(*drp)->dr_next;
3075 ASSERT(dr->dr_next == NULL);
3076 ASSERT(dr->dr_dbuf == db);
3077 *drp = dr->dr_next;
3078 kmem_free(dr, sizeof (dbuf_dirty_record_t));
3079 ASSERT(db->db_dirtycnt > 0);
3080 db->db_dirtycnt -= 1;
3081 dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg);
3082 return;
3083 }
3084
3085 os = dn->dn_objset;
3086
3087 /*
3088 * This function may have dropped the db_mtx lock allowing a dmu_sync
3089 * operation to sneak in. As a result, we need to ensure that we
3090 * don't check the dr_override_state until we have returned from
3091 * dbuf_check_blkptr.
3092 */
3093 dbuf_check_blkptr(dn, db);
3094
3095 /*
3096 * If this buffer is in the middle of an immediate write,
3097 * wait for the synchronous IO to complete.
3098 */
3099 while (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC) {
3100 ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
3101 cv_wait(&db->db_changed, &db->db_mtx);
3102 ASSERT(dr->dt.dl.dr_override_state != DR_NOT_OVERRIDDEN);
3103 }
3104
3105 if (db->db_state != DB_NOFILL &&
3106 dn->dn_object != DMU_META_DNODE_OBJECT &&
3107 refcount_count(&db->db_holds) > 1 &&
3108 dr->dt.dl.dr_override_state != DR_OVERRIDDEN &&
3109 *datap == db->db_buf) {
3110 /*
3111 * If this buffer is currently "in use" (i.e., there
3112 * are active holds and db_data still references it),
3113 * then make a copy before we start the write so that
3114 * any modifications from the open txg will not leak
3115 * into this write.
3116 *
3117 * NOTE: this copy does not need to be made for
3118 * objects only modified in the syncing context (e.g.
3119 * DNONE_DNODE blocks).
3120 */
3121 int psize = arc_buf_size(*datap);
3122 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
3123 enum zio_compress compress_type = arc_get_compression(*datap);
3124
3125 if (compress_type == ZIO_COMPRESS_OFF) {
3126 *datap = arc_alloc_buf(os->os_spa, db, type, psize);
3127 } else {
3128 ASSERT3U(type, ==, ARC_BUFC_DATA);
3129 int lsize = arc_buf_lsize(*datap);
3130 *datap = arc_alloc_compressed_buf(os->os_spa, db,
3131 psize, lsize, compress_type);
3132 }
3133 bcopy(db->db.db_data, (*datap)->b_data, psize);
3134 }
3135 db->db_data_pending = dr;
3136
3137 mutex_exit(&db->db_mtx);
3138
3139 dbuf_write(dr, *datap, tx);
3140
3141 ASSERT(!list_link_active(&dr->dr_dirty_node));
3142 if (dn->dn_object == DMU_META_DNODE_OBJECT) {
3143 list_insert_tail(&dn->dn_dirty_records[txg&TXG_MASK], dr);
3144 DB_DNODE_EXIT(db);
3145 } else {
3146 /*
3147 * Although zio_nowait() does not "wait for an IO", it does
3148 * initiate the IO. If this is an empty write it seems plausible
3149 * that the IO could actually be completed before the nowait
3150 * returns. We need to DB_DNODE_EXIT() first in case
3151 * zio_nowait() invalidates the dbuf.
3152 */
3153 DB_DNODE_EXIT(db);
3154 zio_nowait(dr->dr_zio);
3155 }
3156 }
3157
3158 void
3159 dbuf_sync_list(list_t *list, int level, dmu_tx_t *tx)
3160 {
3161 dbuf_dirty_record_t *dr;
3162
3163 while (dr = list_head(list)) {
3164 if (dr->dr_zio != NULL) {
3165 /*
3166 * If we find an already initialized zio then we
3167 * are processing the meta-dnode, and we have finished.
3168 * The dbufs for all dnodes are put back on the list
3169 * during processing, so that we can zio_wait()
3170 * these IOs after initiating all child IOs.
3171 */
3172 ASSERT3U(dr->dr_dbuf->db.db_object, ==,
3173 DMU_META_DNODE_OBJECT);
3174 break;
3175 }
3176 if (dr->dr_dbuf->db_blkid != DMU_BONUS_BLKID &&
3177 dr->dr_dbuf->db_blkid != DMU_SPILL_BLKID) {
3178 VERIFY3U(dr->dr_dbuf->db_level, ==, level);
3179 }
3180 list_remove(list, dr);
3181 if (dr->dr_dbuf->db_level > 0)
3182 dbuf_sync_indirect(dr, tx);
3183 else
3184 dbuf_sync_leaf(dr, tx);
3185 }
3186 }
3187
3188 /* ARGSUSED */
3189 static void
3190 dbuf_write_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
3191 {
3192 dmu_buf_impl_t *db = vdb;
3193 dnode_t *dn;
3194 blkptr_t *bp = zio->io_bp;
3195 blkptr_t *bp_orig = &zio->io_bp_orig;
3196 spa_t *spa = zio->io_spa;
3197 int64_t delta;
3198 uint64_t fill = 0;
3199 int i;
3200
3201 ASSERT3P(db->db_blkptr, !=, NULL);
3202 ASSERT3P(&db->db_data_pending->dr_bp_copy, ==, bp);
3203
3204 DB_DNODE_ENTER(db);
3205 dn = DB_DNODE(db);
3206 delta = bp_get_dsize_sync(spa, bp) - bp_get_dsize_sync(spa, bp_orig);
3207 dnode_diduse_space(dn, delta - zio->io_prev_space_delta);
3208 zio->io_prev_space_delta = delta;
3209
3210 if (bp->blk_birth != 0) {
3211 ASSERT((db->db_blkid != DMU_SPILL_BLKID &&
3212 BP_GET_TYPE(bp) == dn->dn_type) ||
3213 (db->db_blkid == DMU_SPILL_BLKID &&
3214 BP_GET_TYPE(bp) == dn->dn_bonustype) ||
3215 BP_IS_EMBEDDED(bp));
3216 ASSERT(BP_GET_LEVEL(bp) == db->db_level);
3217 }
3218
3219 mutex_enter(&db->db_mtx);
3220
3221 #ifdef ZFS_DEBUG
3222 if (db->db_blkid == DMU_SPILL_BLKID) {
3223 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
3224 ASSERT(!(BP_IS_HOLE(bp)) &&
3225 db->db_blkptr == &dn->dn_phys->dn_spill);
3226 }
3227 #endif
3228
3229 if (db->db_level == 0) {
3230 mutex_enter(&dn->dn_mtx);
3231 if (db->db_blkid > dn->dn_phys->dn_maxblkid &&
3232 db->db_blkid != DMU_SPILL_BLKID)
3233 dn->dn_phys->dn_maxblkid = db->db_blkid;
3234 mutex_exit(&dn->dn_mtx);
3235
3236 if (dn->dn_type == DMU_OT_DNODE) {
3237 dnode_phys_t *dnp = db->db.db_data;
3238 for (i = db->db.db_size >> DNODE_SHIFT; i > 0;
3239 i--, dnp++) {
3240 if (dnp->dn_type != DMU_OT_NONE)
3241 fill++;
3242 }
3243 } else {
3244 if (BP_IS_HOLE(bp)) {
3245 fill = 0;
3246 } else {
3247 fill = 1;
3248 }
3249 }
3250 } else {
3251 blkptr_t *ibp = db->db.db_data;
3252 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
3253 for (i = db->db.db_size >> SPA_BLKPTRSHIFT; i > 0; i--, ibp++) {
3254 if (BP_IS_HOLE(ibp))
3255 continue;
3256 fill += BP_GET_FILL(ibp);
3257 }
3258 }
3259 DB_DNODE_EXIT(db);
3260
3261 if (!BP_IS_EMBEDDED(bp))
3262 bp->blk_fill = fill;
3263
3264 mutex_exit(&db->db_mtx);
3265
3266 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
3267 *db->db_blkptr = *bp;
3268 rw_exit(&dn->dn_struct_rwlock);
3269 }
3270
3271 /* ARGSUSED */
3272 /*
3273 * This function gets called just prior to running through the compression
3274 * stage of the zio pipeline. If we're an indirect block comprised of only
3275 * holes, then we want this indirect to be compressed away to a hole. In
3276 * order to do that we must zero out any information about the holes that
3277 * this indirect points to prior to before we try to compress it.
3278 */
3279 static void
3280 dbuf_write_children_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
3281 {
3282 dmu_buf_impl_t *db = vdb;
3283 dnode_t *dn;
3284 blkptr_t *bp;
3285 unsigned int epbs, i;
3286
3287 ASSERT3U(db->db_level, >, 0);
3288 DB_DNODE_ENTER(db);
3289 dn = DB_DNODE(db);
3290 epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
3291 ASSERT3U(epbs, <, 31);
3292
3293 /* Determine if all our children are holes */
3294 for (i = 0, bp = db->db.db_data; i < 1 << epbs; i++, bp++) {
3295 if (!BP_IS_HOLE(bp))
3296 break;
3297 }
3298
3299 /*
3300 * If all the children are holes, then zero them all out so that
3301 * we may get compressed away.
3302 */
3303 if (i == 1 << epbs) {
3304 /*
3305 * We only found holes. Grab the rwlock to prevent
3306 * anybody from reading the blocks we're about to
3307 * zero out.
3308 */
3309 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
3310 bzero(db->db.db_data, db->db.db_size);
3311 rw_exit(&dn->dn_struct_rwlock);
3312 }
3313 DB_DNODE_EXIT(db);
3314 }
3315
3316 /*
3317 * The SPA will call this callback several times for each zio - once
3318 * for every physical child i/o (zio->io_phys_children times). This
3319 * allows the DMU to monitor the progress of each logical i/o. For example,
3320 * there may be 2 copies of an indirect block, or many fragments of a RAID-Z
3321 * block. There may be a long delay before all copies/fragments are completed,
3322 * so this callback allows us to retire dirty space gradually, as the physical
3323 * i/os complete.
3324 */
3325 /* ARGSUSED */
3326 static void
3327 dbuf_write_physdone(zio_t *zio, arc_buf_t *buf, void *arg)
3328 {
3329 dmu_buf_impl_t *db = arg;
3330 objset_t *os = db->db_objset;
3331 dsl_pool_t *dp = dmu_objset_pool(os);
3332 dbuf_dirty_record_t *dr;
3333 int delta = 0;
3334
3335 dr = db->db_data_pending;
3336 ASSERT3U(dr->dr_txg, ==, zio->io_txg);
3337
3338 /*
3339 * The callback will be called io_phys_children times. Retire one
3340 * portion of our dirty space each time we are called. Any rounding
3341 * error will be cleaned up by dsl_pool_sync()'s call to
3342 * dsl_pool_undirty_space().
3343 */
3344 delta = dr->dr_accounted / zio->io_phys_children;
3345 dsl_pool_undirty_space(dp, delta, zio->io_txg);
3346 }
3347
3348 /* ARGSUSED */
3349 static void
3350 dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb)
3351 {
3352 dmu_buf_impl_t *db = vdb;
3353 blkptr_t *bp_orig = &zio->io_bp_orig;
3354 blkptr_t *bp = db->db_blkptr;
3355 objset_t *os = db->db_objset;
3356 dmu_tx_t *tx = os->os_synctx;
3357 dbuf_dirty_record_t **drp, *dr;
3358
3359 ASSERT0(zio->io_error);
3360 ASSERT(db->db_blkptr == bp);
3361
3362 /*
3363 * For nopwrites and rewrites we ensure that the bp matches our
3364 * original and bypass all the accounting.
3365 */
3366 if (zio->io_flags & (ZIO_FLAG_IO_REWRITE | ZIO_FLAG_NOPWRITE)) {
3367 ASSERT(BP_EQUAL(bp, bp_orig));
3368 } else {
3369 dsl_dataset_t *ds = os->os_dsl_dataset;
3370 (void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE);
3371 dsl_dataset_block_born(ds, bp, tx);
3372 }
3373
3374 mutex_enter(&db->db_mtx);
3375
3376 DBUF_VERIFY(db);
3377
3378 drp = &db->db_last_dirty;
3379 while ((dr = *drp) != db->db_data_pending)
3380 drp = &dr->dr_next;
3381 ASSERT(!list_link_active(&dr->dr_dirty_node));
3382 ASSERT(dr->dr_dbuf == db);
3383 ASSERT(dr->dr_next == NULL);
3384 *drp = dr->dr_next;
3385
3386 #ifdef ZFS_DEBUG
3387 if (db->db_blkid == DMU_SPILL_BLKID) {
3388 dnode_t *dn;
3389
3390 DB_DNODE_ENTER(db);
3391 dn = DB_DNODE(db);
3392 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
3393 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
3394 db->db_blkptr == &dn->dn_phys->dn_spill);
3395 DB_DNODE_EXIT(db);
3396 }
3397 #endif
3398
3399 if (db->db_level == 0) {
3400 ASSERT(db->db_blkid != DMU_BONUS_BLKID);
3401 ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
3402 if (db->db_state != DB_NOFILL) {
3403 if (dr->dt.dl.dr_data != db->db_buf)
3404 arc_buf_destroy(dr->dt.dl.dr_data, db);
3405 }
3406 } else {
3407 dnode_t *dn;
3408
3409 DB_DNODE_ENTER(db);
3410 dn = DB_DNODE(db);
3411 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
3412 ASSERT3U(db->db.db_size, ==, 1 << dn->dn_phys->dn_indblkshift);
3413 if (!BP_IS_HOLE(db->db_blkptr)) {
3414 int epbs =
3415 dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
3416 ASSERT3U(db->db_blkid, <=,
3417 dn->dn_phys->dn_maxblkid >> (db->db_level * epbs));
3418 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==,
3419 db->db.db_size);
3420 }
3421 DB_DNODE_EXIT(db);
3422 mutex_destroy(&dr->dt.di.dr_mtx);
3423 list_destroy(&dr->dt.di.dr_children);
3424 }
3425 kmem_free(dr, sizeof (dbuf_dirty_record_t));
3426
3427 cv_broadcast(&db->db_changed);
3428 ASSERT(db->db_dirtycnt > 0);
3429 db->db_dirtycnt -= 1;
3430 db->db_data_pending = NULL;
3431 dbuf_rele_and_unlock(db, (void *)(uintptr_t)tx->tx_txg);
3432 }
3433
3434 static void
3435 dbuf_write_nofill_ready(zio_t *zio)
3436 {
3437 dbuf_write_ready(zio, NULL, zio->io_private);
3438 }
3439
3440 static void
3441 dbuf_write_nofill_done(zio_t *zio)
3442 {
3443 dbuf_write_done(zio, NULL, zio->io_private);
3444 }
3445
3446 static void
3447 dbuf_write_override_ready(zio_t *zio)
3448 {
3449 dbuf_dirty_record_t *dr = zio->io_private;
3450 dmu_buf_impl_t *db = dr->dr_dbuf;
3451
3452 dbuf_write_ready(zio, NULL, db);
3453 }
3454
3455 static void
3456 dbuf_write_override_done(zio_t *zio)
3457 {
3458 dbuf_dirty_record_t *dr = zio->io_private;
3459 dmu_buf_impl_t *db = dr->dr_dbuf;
3460 blkptr_t *obp = &dr->dt.dl.dr_overridden_by;
3461
3462 mutex_enter(&db->db_mtx);
3463 if (!BP_EQUAL(zio->io_bp, obp)) {
3464 if (!BP_IS_HOLE(obp))
3465 dsl_free(spa_get_dsl(zio->io_spa), zio->io_txg, obp);
3466 arc_release(dr->dt.dl.dr_data, db);
3467 }
3468 mutex_exit(&db->db_mtx);
3469 dbuf_write_done(zio, NULL, db);
3470
3471 if (zio->io_abd != NULL)
3472 abd_put(zio->io_abd);
3473 }
3474
3475 typedef struct dbuf_remap_impl_callback_arg {
3476 objset_t *drica_os;
3477 uint64_t drica_blk_birth;
3478 dmu_tx_t *drica_tx;
3479 } dbuf_remap_impl_callback_arg_t;
3480
3481 static void
3482 dbuf_remap_impl_callback(uint64_t vdev, uint64_t offset, uint64_t size,
3483 void *arg)
3484 {
3485 dbuf_remap_impl_callback_arg_t *drica = arg;
3486 objset_t *os = drica->drica_os;
3487 spa_t *spa = dmu_objset_spa(os);
3488 dmu_tx_t *tx = drica->drica_tx;
3489
3490 ASSERT(dsl_pool_sync_context(spa_get_dsl(spa)));
3491
3492 if (os == spa_meta_objset(spa)) {
3493 spa_vdev_indirect_mark_obsolete(spa, vdev, offset, size, tx);
3494 } else {
3495 dsl_dataset_block_remapped(dmu_objset_ds(os), vdev, offset,
3496 size, drica->drica_blk_birth, tx);
3497 }
3498 }
3499
3500 static void
3501 dbuf_remap_impl(dnode_t *dn, blkptr_t *bp, dmu_tx_t *tx)
3502 {
3503 blkptr_t bp_copy = *bp;
3504 spa_t *spa = dmu_objset_spa(dn->dn_objset);
3505 dbuf_remap_impl_callback_arg_t drica;
3506
3507 ASSERT(dsl_pool_sync_context(spa_get_dsl(spa)));
3508
3509 drica.drica_os = dn->dn_objset;
3510 drica.drica_blk_birth = bp->blk_birth;
3511 drica.drica_tx = tx;
3512 if (spa_remap_blkptr(spa, &bp_copy, dbuf_remap_impl_callback,
3513 &drica)) {
3514 /*
3515 * The struct_rwlock prevents dbuf_read_impl() from
3516 * dereferencing the BP while we are changing it. To
3517 * avoid lock contention, only grab it when we are actually
3518 * changing the BP.
3519 */
3520 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
3521 *bp = bp_copy;
3522 rw_exit(&dn->dn_struct_rwlock);
3523 }
3524 }
3525
3526 /*
3527 * Returns true if a dbuf_remap would modify the dbuf. We do this by attempting
3528 * to remap a copy of every bp in the dbuf.
3529 */
3530 boolean_t
3531 dbuf_can_remap(const dmu_buf_impl_t *db)
3532 {
3533 spa_t *spa = dmu_objset_spa(db->db_objset);
3534 blkptr_t *bp = db->db.db_data;
3535 boolean_t ret = B_FALSE;
3536
3537 ASSERT3U(db->db_level, >, 0);
3538 ASSERT3S(db->db_state, ==, DB_CACHED);
3539
3540 ASSERT(spa_feature_is_active(spa, SPA_FEATURE_DEVICE_REMOVAL));
3541
3542 spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);
3543 for (int i = 0; i < db->db.db_size >> SPA_BLKPTRSHIFT; i++) {
3544 blkptr_t bp_copy = bp[i];
3545 if (spa_remap_blkptr(spa, &bp_copy, NULL, NULL)) {
3546 ret = B_TRUE;
3547 break;
3548 }
3549 }
3550 spa_config_exit(spa, SCL_VDEV, FTAG);
3551
3552 return (ret);
3553 }
3554
3555 boolean_t
3556 dnode_needs_remap(const dnode_t *dn)
3557 {
3558 spa_t *spa = dmu_objset_spa(dn->dn_objset);
3559 boolean_t ret = B_FALSE;
3560
3561 if (dn->dn_phys->dn_nlevels == 0) {
3562 return (B_FALSE);
3563 }
3564
3565 ASSERT(spa_feature_is_active(spa, SPA_FEATURE_DEVICE_REMOVAL));
3566
3567 spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);
3568 for (int j = 0; j < dn->dn_phys->dn_nblkptr; j++) {
3569 blkptr_t bp_copy = dn->dn_phys->dn_blkptr[j];
3570 if (spa_remap_blkptr(spa, &bp_copy, NULL, NULL)) {
3571 ret = B_TRUE;
3572 break;
3573 }
3574 }
3575 spa_config_exit(spa, SCL_VDEV, FTAG);
3576
3577 return (ret);
3578 }
3579
3580 /*
3581 * Remap any existing BP's to concrete vdevs, if possible.
3582 */
3583 static void
3584 dbuf_remap(dnode_t *dn, dmu_buf_impl_t *db, dmu_tx_t *tx)
3585 {
3586 spa_t *spa = dmu_objset_spa(db->db_objset);
3587 ASSERT(dsl_pool_sync_context(spa_get_dsl(spa)));
3588
3589 if (!spa_feature_is_active(spa, SPA_FEATURE_DEVICE_REMOVAL))
3590 return;
3591
3592 if (db->db_level > 0) {
3593 blkptr_t *bp = db->db.db_data;
3594 for (int i = 0; i < db->db.db_size >> SPA_BLKPTRSHIFT; i++) {
3595 dbuf_remap_impl(dn, &bp[i], tx);
3596 }
3597 } else if (db->db.db_object == DMU_META_DNODE_OBJECT) {
3598 dnode_phys_t *dnp = db->db.db_data;
3599 ASSERT3U(db->db_dnode_handle->dnh_dnode->dn_type, ==,
3600 DMU_OT_DNODE);
3601 for (int i = 0; i < db->db.db_size >> DNODE_SHIFT; i++) {
3602 for (int j = 0; j < dnp[i].dn_nblkptr; j++) {
3603 dbuf_remap_impl(dn, &dnp[i].dn_blkptr[j], tx);
3604 }
3605 }
3606 }
3607 }
3608
3609
3610 /* Issue I/O to commit a dirty buffer to disk. */
3611 static void
3612 dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx)
3613 {
3614 dmu_buf_impl_t *db = dr->dr_dbuf;
3615 dnode_t *dn;
3616 objset_t *os;
3617 dmu_buf_impl_t *parent = db->db_parent;
3618 uint64_t txg = tx->tx_txg;
3619 zbookmark_phys_t zb;
3620 zio_prop_t zp;
3621 zio_t *zio;
3622 int wp_flag = 0;
3623
3624 ASSERT(dmu_tx_is_syncing(tx));
3625
3626 DB_DNODE_ENTER(db);
3627 dn = DB_DNODE(db);
3628 os = dn->dn_objset;
3629
3630 if (db->db_state != DB_NOFILL) {
3631 if (db->db_level > 0 || dn->dn_type == DMU_OT_DNODE) {
3632 /*
3633 * Private object buffers are released here rather
3634 * than in dbuf_dirty() since they are only modified
3635 * in the syncing context and we don't want the
3636 * overhead of making multiple copies of the data.
3637 */
3638 if (BP_IS_HOLE(db->db_blkptr)) {
3639 arc_buf_thaw(data);
3640 } else {
3641 dbuf_release_bp(db);
3642 }
3643 dbuf_remap(dn, db, tx);
3644 }
3645 }
3646
3647 if (parent != dn->dn_dbuf) {
3648 /* Our parent is an indirect block. */
3649 /* We have a dirty parent that has been scheduled for write. */
3650 ASSERT(parent && parent->db_data_pending);
3651 /* Our parent's buffer is one level closer to the dnode. */
3652 ASSERT(db->db_level == parent->db_level-1);
3653 /*
3654 * We're about to modify our parent's db_data by modifying
3655 * our block pointer, so the parent must be released.
3656 */
3657 ASSERT(arc_released(parent->db_buf));
3658 zio = parent->db_data_pending->dr_zio;
3659 } else {
3660 /* Our parent is the dnode itself. */
3661 ASSERT((db->db_level == dn->dn_phys->dn_nlevels-1 &&
3662 db->db_blkid != DMU_SPILL_BLKID) ||
3663 (db->db_blkid == DMU_SPILL_BLKID && db->db_level == 0));
3664 if (db->db_blkid != DMU_SPILL_BLKID)
3665 ASSERT3P(db->db_blkptr, ==,
3666 &dn->dn_phys->dn_blkptr[db->db_blkid]);
3667 zio = dn->dn_zio;
3668 }
3669
3670 ASSERT(db->db_level == 0 || data == db->db_buf);
3671 ASSERT3U(db->db_blkptr->blk_birth, <=, txg);
3672 ASSERT(zio);
3673
3674 SET_BOOKMARK(&zb, os->os_dsl_dataset ?
3675 os->os_dsl_dataset->ds_object : DMU_META_OBJSET,
3676 db->db.db_object, db->db_level, db->db_blkid);
3677
3678 if (db->db_blkid == DMU_SPILL_BLKID)
3679 wp_flag = WP_SPILL;
3680 wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0;
3681
3682 dmu_write_policy(os, dn, db->db_level, wp_flag, &zp);
3683 DB_DNODE_EXIT(db);
3684
3685 /*
3686 * We copy the blkptr now (rather than when we instantiate the dirty
3687 * record), because its value can change between open context and
3688 * syncing context. We do not need to hold dn_struct_rwlock to read
3689 * db_blkptr because we are in syncing context.
3690 */
3691 dr->dr_bp_copy = *db->db_blkptr;
3692
3693 if (db->db_level == 0 &&
3694 dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
3695 /*
3696 * The BP for this block has been provided by open context
3697 * (by dmu_sync() or dmu_buf_write_embedded()).
3698 */
3699 abd_t *contents = (data != NULL) ?
3700 abd_get_from_buf(data->b_data, arc_buf_size(data)) : NULL;
3701
3702 dr->dr_zio = zio_write(zio, os->os_spa, txg, &dr->dr_bp_copy,
3703 contents, db->db.db_size, db->db.db_size, &zp,
3704 dbuf_write_override_ready, NULL, NULL,
3705 dbuf_write_override_done,
3706 dr, ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
3707 mutex_enter(&db->db_mtx);
3708 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
3709 zio_write_override(dr->dr_zio, &dr->dt.dl.dr_overridden_by,
3710 dr->dt.dl.dr_copies, dr->dt.dl.dr_nopwrite);
3711 mutex_exit(&db->db_mtx);
3712 } else if (db->db_state == DB_NOFILL) {
3713 ASSERT(zp.zp_checksum == ZIO_CHECKSUM_OFF ||
3714 zp.zp_checksum == ZIO_CHECKSUM_NOPARITY);
3715 dr->dr_zio = zio_write(zio, os->os_spa, txg,
3716 &dr->dr_bp_copy, NULL, db->db.db_size, db->db.db_size, &zp,
3717 dbuf_write_nofill_ready, NULL, NULL,
3718 dbuf_write_nofill_done, db,
3719 ZIO_PRIORITY_ASYNC_WRITE,
3720 ZIO_FLAG_MUSTSUCCEED | ZIO_FLAG_NODATA, &zb);
3721 } else {
3722 ASSERT(arc_released(data));
3723
3724 /*
3725 * For indirect blocks, we want to setup the children
3726 * ready callback so that we can properly handle an indirect
3727 * block that only contains holes.
3728 */
3729 arc_done_func_t *children_ready_cb = NULL;
3730 if (db->db_level != 0)
3731 children_ready_cb = dbuf_write_children_ready;
3732
3733 dr->dr_zio = arc_write(zio, os->os_spa, txg,
3734 &dr->dr_bp_copy, data, DBUF_IS_L2CACHEABLE(db),
3735 &zp, dbuf_write_ready, children_ready_cb,
3736 dbuf_write_physdone, dbuf_write_done, db,
3737 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
3738 }
3739 }