xref: /illumos-gate/usr/src/uts/common/fs/zfs/dnode_sync.c (revision 553e44ce7e541a9e1404b1ead92be0753668710a)
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 /*
23  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
24  * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
25  * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
26  */
27 
28 #include <sys/zfs_context.h>
29 #include <sys/dbuf.h>
30 #include <sys/dnode.h>
31 #include <sys/dmu.h>
32 #include <sys/dmu_tx.h>
33 #include <sys/dmu_objset.h>
34 #include <sys/dsl_dataset.h>
35 #include <sys/spa.h>
36 #include <sys/range_tree.h>
37 #include <sys/zfeature.h>
38 
39 static void
40 dnode_increase_indirection(dnode_t *dn, dmu_tx_t *tx)
41 {
42 	dmu_buf_impl_t *db;
43 	int txgoff = tx->tx_txg & TXG_MASK;
44 	int nblkptr = dn->dn_phys->dn_nblkptr;
45 	int old_toplvl = dn->dn_phys->dn_nlevels - 1;
46 	int new_level = dn->dn_next_nlevels[txgoff];
47 	int i;
48 
49 	rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
50 
51 	/* this dnode can't be paged out because it's dirty */
52 	ASSERT(dn->dn_phys->dn_type != DMU_OT_NONE);
53 	ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
54 	ASSERT(new_level > 1 && dn->dn_phys->dn_nlevels > 0);
55 
56 	db = dbuf_hold_level(dn, dn->dn_phys->dn_nlevels, 0, FTAG);
57 	ASSERT(db != NULL);
58 
59 	dn->dn_phys->dn_nlevels = new_level;
60 	dprintf("os=%p obj=%llu, increase to %d\n", dn->dn_objset,
61 	    dn->dn_object, dn->dn_phys->dn_nlevels);
62 
63 	/* transfer dnode's block pointers to new indirect block */
64 	(void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED|DB_RF_HAVESTRUCT);
65 	ASSERT(db->db.db_data);
66 	ASSERT(arc_released(db->db_buf));
67 	ASSERT3U(sizeof (blkptr_t) * nblkptr, <=, db->db.db_size);
68 	bcopy(dn->dn_phys->dn_blkptr, db->db.db_data,
69 	    sizeof (blkptr_t) * nblkptr);
70 	arc_buf_freeze(db->db_buf);
71 
72 	/* set dbuf's parent pointers to new indirect buf */
73 	for (i = 0; i < nblkptr; i++) {
74 		dmu_buf_impl_t *child =
75 		    dbuf_find(dn->dn_objset, dn->dn_object, old_toplvl, i);
76 
77 		if (child == NULL)
78 			continue;
79 #ifdef	DEBUG
80 		DB_DNODE_ENTER(child);
81 		ASSERT3P(DB_DNODE(child), ==, dn);
82 		DB_DNODE_EXIT(child);
83 #endif	/* DEBUG */
84 		if (child->db_parent && child->db_parent != dn->dn_dbuf) {
85 			ASSERT(child->db_parent->db_level == db->db_level);
86 			ASSERT(child->db_blkptr !=
87 			    &dn->dn_phys->dn_blkptr[child->db_blkid]);
88 			mutex_exit(&child->db_mtx);
89 			continue;
90 		}
91 		ASSERT(child->db_parent == NULL ||
92 		    child->db_parent == dn->dn_dbuf);
93 
94 		child->db_parent = db;
95 		dbuf_add_ref(db, child);
96 		if (db->db.db_data)
97 			child->db_blkptr = (blkptr_t *)db->db.db_data + i;
98 		else
99 			child->db_blkptr = NULL;
100 		dprintf_dbuf_bp(child, child->db_blkptr,
101 		    "changed db_blkptr to new indirect %s", "");
102 
103 		mutex_exit(&child->db_mtx);
104 	}
105 
106 	bzero(dn->dn_phys->dn_blkptr, sizeof (blkptr_t) * nblkptr);
107 
108 	dbuf_rele(db, FTAG);
109 
110 	rw_exit(&dn->dn_struct_rwlock);
111 }
112 
113 static void
114 free_blocks(dnode_t *dn, blkptr_t *bp, int num, dmu_tx_t *tx)
115 {
116 	dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset;
117 	uint64_t bytesfreed = 0;
118 
119 	dprintf("ds=%p obj=%llx num=%d\n", ds, dn->dn_object, num);
120 
121 	for (int i = 0; i < num; i++, bp++) {
122 		if (BP_IS_HOLE(bp))
123 			continue;
124 
125 		bytesfreed += dsl_dataset_block_kill(ds, bp, tx, B_FALSE);
126 		ASSERT3U(bytesfreed, <=, DN_USED_BYTES(dn->dn_phys));
127 
128 		/*
129 		 * Save some useful information on the holes being
130 		 * punched, including logical size, type, and indirection
131 		 * level. Retaining birth time enables detection of when
132 		 * holes are punched for reducing the number of free
133 		 * records transmitted during a zfs send.
134 		 */
135 
136 		uint64_t lsize = BP_GET_LSIZE(bp);
137 		dmu_object_type_t type = BP_GET_TYPE(bp);
138 		uint64_t lvl = BP_GET_LEVEL(bp);
139 
140 		bzero(bp, sizeof (blkptr_t));
141 
142 		if (spa_feature_is_active(dn->dn_objset->os_spa,
143 		    SPA_FEATURE_HOLE_BIRTH)) {
144 			BP_SET_LSIZE(bp, lsize);
145 			BP_SET_TYPE(bp, type);
146 			BP_SET_LEVEL(bp, lvl);
147 			BP_SET_BIRTH(bp, dmu_tx_get_txg(tx), 0);
148 		}
149 	}
150 	dnode_diduse_space(dn, -bytesfreed);
151 }
152 
153 #ifdef ZFS_DEBUG
154 static void
155 free_verify(dmu_buf_impl_t *db, uint64_t start, uint64_t end, dmu_tx_t *tx)
156 {
157 	int off, num;
158 	int i, err, epbs;
159 	uint64_t txg = tx->tx_txg;
160 	dnode_t *dn;
161 
162 	DB_DNODE_ENTER(db);
163 	dn = DB_DNODE(db);
164 	epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
165 	off = start - (db->db_blkid * 1<<epbs);
166 	num = end - start + 1;
167 
168 	ASSERT3U(off, >=, 0);
169 	ASSERT3U(num, >=, 0);
170 	ASSERT3U(db->db_level, >, 0);
171 	ASSERT3U(db->db.db_size, ==, 1 << dn->dn_phys->dn_indblkshift);
172 	ASSERT3U(off+num, <=, db->db.db_size >> SPA_BLKPTRSHIFT);
173 	ASSERT(db->db_blkptr != NULL);
174 
175 	for (i = off; i < off+num; i++) {
176 		uint64_t *buf;
177 		dmu_buf_impl_t *child;
178 		dbuf_dirty_record_t *dr;
179 		int j;
180 
181 		ASSERT(db->db_level == 1);
182 
183 		rw_enter(&dn->dn_struct_rwlock, RW_READER);
184 		err = dbuf_hold_impl(dn, db->db_level-1,
185 		    (db->db_blkid << epbs) + i, TRUE, FALSE, FTAG, &child);
186 		rw_exit(&dn->dn_struct_rwlock);
187 		if (err == ENOENT)
188 			continue;
189 		ASSERT(err == 0);
190 		ASSERT(child->db_level == 0);
191 		dr = child->db_last_dirty;
192 		while (dr && dr->dr_txg > txg)
193 			dr = dr->dr_next;
194 		ASSERT(dr == NULL || dr->dr_txg == txg);
195 
196 		/* data_old better be zeroed */
197 		if (dr) {
198 			buf = dr->dt.dl.dr_data->b_data;
199 			for (j = 0; j < child->db.db_size >> 3; j++) {
200 				if (buf[j] != 0) {
201 					panic("freed data not zero: "
202 					    "child=%p i=%d off=%d num=%d\n",
203 					    (void *)child, i, off, num);
204 				}
205 			}
206 		}
207 
208 		/*
209 		 * db_data better be zeroed unless it's dirty in a
210 		 * future txg.
211 		 */
212 		mutex_enter(&child->db_mtx);
213 		buf = child->db.db_data;
214 		if (buf != NULL && child->db_state != DB_FILL &&
215 		    child->db_last_dirty == NULL) {
216 			for (j = 0; j < child->db.db_size >> 3; j++) {
217 				if (buf[j] != 0) {
218 					panic("freed data not zero: "
219 					    "child=%p i=%d off=%d num=%d\n",
220 					    (void *)child, i, off, num);
221 				}
222 			}
223 		}
224 		mutex_exit(&child->db_mtx);
225 
226 		dbuf_rele(child, FTAG);
227 	}
228 	DB_DNODE_EXIT(db);
229 }
230 #endif
231 
232 /*
233  * We don't usually free the indirect blocks here.  If in one txg we have a
234  * free_range and a write to the same indirect block, it's important that we
235  * preserve the hole's birth times. Therefore, we don't free any any indirect
236  * blocks in free_children().  If an indirect block happens to turn into all
237  * holes, it will be freed by dbuf_write_children_ready, which happens at a
238  * point in the syncing process where we know for certain the contents of the
239  * indirect block.
240  *
241  * However, if we're freeing a dnode, its space accounting must go to zero
242  * before we actually try to free the dnode, or we will trip an assertion. In
243  * addition, we know the case described above cannot occur, because the dnode is
244  * being freed.  Therefore, we free the indirect blocks immediately in that
245  * case.
246  */
247 static void
248 free_children(dmu_buf_impl_t *db, uint64_t blkid, uint64_t nblks,
249     boolean_t free_indirects, dmu_tx_t *tx)
250 {
251 	dnode_t *dn;
252 	blkptr_t *bp;
253 	dmu_buf_impl_t *subdb;
254 	uint64_t start, end, dbstart, dbend;
255 	unsigned int epbs, shift, i;
256 
257 	/*
258 	 * There is a small possibility that this block will not be cached:
259 	 *   1 - if level > 1 and there are no children with level <= 1
260 	 *   2 - if this block was evicted since we read it from
261 	 *	 dmu_tx_hold_free().
262 	 */
263 	if (db->db_state != DB_CACHED)
264 		(void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED);
265 
266 	/*
267 	 * If we modify this indirect block, and we are not freeing the
268 	 * dnode (!free_indirects), then this indirect block needs to get
269 	 * written to disk by dbuf_write().  If it is dirty, we know it will
270 	 * be written (otherwise, we would have incorrect on-disk state
271 	 * because the space would be freed but still referenced by the BP
272 	 * in this indirect block).  Therefore we VERIFY that it is
273 	 * dirty.
274 	 *
275 	 * Our VERIFY covers some cases that do not actually have to be
276 	 * dirty, but the open-context code happens to dirty.  E.g. if the
277 	 * blocks we are freeing are all holes, because in that case, we
278 	 * are only freeing part of this indirect block, so it is an
279 	 * ancestor of the first or last block to be freed.  The first and
280 	 * last L1 indirect blocks are always dirtied by dnode_free_range().
281 	 */
282 	VERIFY(BP_GET_FILL(db->db_blkptr) == 0 || db->db_dirtycnt > 0);
283 
284 	dbuf_release_bp(db);
285 	bp = db->db.db_data;
286 
287 	DB_DNODE_ENTER(db);
288 	dn = DB_DNODE(db);
289 	epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
290 	ASSERT3U(epbs, <, 31);
291 	shift = (db->db_level - 1) * epbs;
292 	dbstart = db->db_blkid << epbs;
293 	start = blkid >> shift;
294 	if (dbstart < start) {
295 		bp += start - dbstart;
296 	} else {
297 		start = dbstart;
298 	}
299 	dbend = ((db->db_blkid + 1) << epbs) - 1;
300 	end = (blkid + nblks - 1) >> shift;
301 	if (dbend <= end)
302 		end = dbend;
303 
304 	ASSERT3U(start, <=, end);
305 
306 	if (db->db_level == 1) {
307 		FREE_VERIFY(db, start, end, tx);
308 		free_blocks(dn, bp, end-start+1, tx);
309 	} else {
310 		for (uint64_t id = start; id <= end; id++, bp++) {
311 			if (BP_IS_HOLE(bp))
312 				continue;
313 			rw_enter(&dn->dn_struct_rwlock, RW_READER);
314 			VERIFY0(dbuf_hold_impl(dn, db->db_level - 1,
315 			    id, TRUE, FALSE, FTAG, &subdb));
316 			rw_exit(&dn->dn_struct_rwlock);
317 			ASSERT3P(bp, ==, subdb->db_blkptr);
318 
319 			free_children(subdb, blkid, nblks, free_indirects, tx);
320 			dbuf_rele(subdb, FTAG);
321 		}
322 	}
323 
324 	if (free_indirects) {
325 		for (i = 0, bp = db->db.db_data; i < 1 << epbs; i++, bp++)
326 			ASSERT(BP_IS_HOLE(bp));
327 		bzero(db->db.db_data, db->db.db_size);
328 		free_blocks(dn, db->db_blkptr, 1, tx);
329 	}
330 
331 	DB_DNODE_EXIT(db);
332 	arc_buf_freeze(db->db_buf);
333 }
334 
335 /*
336  * Traverse the indicated range of the provided file
337  * and "free" all the blocks contained there.
338  */
339 static void
340 dnode_sync_free_range_impl(dnode_t *dn, uint64_t blkid, uint64_t nblks,
341     boolean_t free_indirects, dmu_tx_t *tx)
342 {
343 	blkptr_t *bp = dn->dn_phys->dn_blkptr;
344 	int dnlevel = dn->dn_phys->dn_nlevels;
345 	boolean_t trunc = B_FALSE;
346 
347 	if (blkid > dn->dn_phys->dn_maxblkid)
348 		return;
349 
350 	ASSERT(dn->dn_phys->dn_maxblkid < UINT64_MAX);
351 	if (blkid + nblks > dn->dn_phys->dn_maxblkid) {
352 		nblks = dn->dn_phys->dn_maxblkid - blkid + 1;
353 		trunc = B_TRUE;
354 	}
355 
356 	/* There are no indirect blocks in the object */
357 	if (dnlevel == 1) {
358 		if (blkid >= dn->dn_phys->dn_nblkptr) {
359 			/* this range was never made persistent */
360 			return;
361 		}
362 		ASSERT3U(blkid + nblks, <=, dn->dn_phys->dn_nblkptr);
363 		free_blocks(dn, bp + blkid, nblks, tx);
364 	} else {
365 		int shift = (dnlevel - 1) *
366 		    (dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT);
367 		int start = blkid >> shift;
368 		int end = (blkid + nblks - 1) >> shift;
369 		dmu_buf_impl_t *db;
370 
371 		ASSERT(start < dn->dn_phys->dn_nblkptr);
372 		bp += start;
373 		for (int i = start; i <= end; i++, bp++) {
374 			if (BP_IS_HOLE(bp))
375 				continue;
376 			rw_enter(&dn->dn_struct_rwlock, RW_READER);
377 			VERIFY0(dbuf_hold_impl(dn, dnlevel - 1, i,
378 			    TRUE, FALSE, FTAG, &db));
379 			rw_exit(&dn->dn_struct_rwlock);
380 
381 			free_children(db, blkid, nblks, free_indirects, tx);
382 			dbuf_rele(db, FTAG);
383 		}
384 	}
385 
386 	if (trunc) {
387 		dn->dn_phys->dn_maxblkid = blkid == 0 ? 0 : blkid - 1;
388 
389 		uint64_t off = (dn->dn_phys->dn_maxblkid + 1) *
390 		    (dn->dn_phys->dn_datablkszsec << SPA_MINBLOCKSHIFT);
391 		ASSERT(off < dn->dn_phys->dn_maxblkid ||
392 		    dn->dn_phys->dn_maxblkid == 0 ||
393 		    dnode_next_offset(dn, 0, &off, 1, 1, 0) != 0);
394 	}
395 }
396 
397 typedef struct dnode_sync_free_range_arg {
398 	dnode_t *dsfra_dnode;
399 	dmu_tx_t *dsfra_tx;
400 	boolean_t dsfra_free_indirects;
401 } dnode_sync_free_range_arg_t;
402 
403 static void
404 dnode_sync_free_range(void *arg, uint64_t blkid, uint64_t nblks)
405 {
406 	dnode_sync_free_range_arg_t *dsfra = arg;
407 	dnode_t *dn = dsfra->dsfra_dnode;
408 
409 	mutex_exit(&dn->dn_mtx);
410 	dnode_sync_free_range_impl(dn, blkid, nblks,
411 	    dsfra->dsfra_free_indirects, dsfra->dsfra_tx);
412 	mutex_enter(&dn->dn_mtx);
413 }
414 
415 /*
416  * Try to kick all the dnode's dbufs out of the cache...
417  */
418 void
419 dnode_evict_dbufs(dnode_t *dn)
420 {
421 	dmu_buf_impl_t db_marker;
422 	dmu_buf_impl_t *db, *db_next;
423 
424 	mutex_enter(&dn->dn_dbufs_mtx);
425 	for (db = avl_first(&dn->dn_dbufs); db != NULL; db = db_next) {
426 
427 #ifdef	DEBUG
428 		DB_DNODE_ENTER(db);
429 		ASSERT3P(DB_DNODE(db), ==, dn);
430 		DB_DNODE_EXIT(db);
431 #endif	/* DEBUG */
432 
433 		mutex_enter(&db->db_mtx);
434 		if (db->db_state != DB_EVICTING &&
435 		    refcount_is_zero(&db->db_holds)) {
436 			db_marker.db_level = db->db_level;
437 			db_marker.db_blkid = db->db_blkid;
438 			db_marker.db_state = DB_SEARCH;
439 			avl_insert_here(&dn->dn_dbufs, &db_marker, db,
440 			    AVL_BEFORE);
441 
442 			dbuf_destroy(db);
443 
444 			db_next = AVL_NEXT(&dn->dn_dbufs, &db_marker);
445 			avl_remove(&dn->dn_dbufs, &db_marker);
446 		} else {
447 			db->db_pending_evict = TRUE;
448 			mutex_exit(&db->db_mtx);
449 			db_next = AVL_NEXT(&dn->dn_dbufs, db);
450 		}
451 	}
452 	mutex_exit(&dn->dn_dbufs_mtx);
453 
454 	dnode_evict_bonus(dn);
455 }
456 
457 void
458 dnode_evict_bonus(dnode_t *dn)
459 {
460 	rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
461 	if (dn->dn_bonus != NULL) {
462 		if (refcount_is_zero(&dn->dn_bonus->db_holds)) {
463 			mutex_enter(&dn->dn_bonus->db_mtx);
464 			dbuf_destroy(dn->dn_bonus);
465 			dn->dn_bonus = NULL;
466 		} else {
467 			dn->dn_bonus->db_pending_evict = TRUE;
468 		}
469 	}
470 	rw_exit(&dn->dn_struct_rwlock);
471 }
472 
473 static void
474 dnode_undirty_dbufs(list_t *list)
475 {
476 	dbuf_dirty_record_t *dr;
477 
478 	while (dr = list_head(list)) {
479 		dmu_buf_impl_t *db = dr->dr_dbuf;
480 		uint64_t txg = dr->dr_txg;
481 
482 		if (db->db_level != 0)
483 			dnode_undirty_dbufs(&dr->dt.di.dr_children);
484 
485 		mutex_enter(&db->db_mtx);
486 		/* XXX - use dbuf_undirty()? */
487 		list_remove(list, dr);
488 		ASSERT(db->db_last_dirty == dr);
489 		db->db_last_dirty = NULL;
490 		db->db_dirtycnt -= 1;
491 		if (db->db_level == 0) {
492 			ASSERT(db->db_blkid == DMU_BONUS_BLKID ||
493 			    dr->dt.dl.dr_data == db->db_buf);
494 			dbuf_unoverride(dr);
495 		} else {
496 			mutex_destroy(&dr->dt.di.dr_mtx);
497 			list_destroy(&dr->dt.di.dr_children);
498 		}
499 		kmem_free(dr, sizeof (dbuf_dirty_record_t));
500 		dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg);
501 	}
502 }
503 
504 static void
505 dnode_sync_free(dnode_t *dn, dmu_tx_t *tx)
506 {
507 	int txgoff = tx->tx_txg & TXG_MASK;
508 
509 	ASSERT(dmu_tx_is_syncing(tx));
510 
511 	/*
512 	 * Our contents should have been freed in dnode_sync() by the
513 	 * free range record inserted by the caller of dnode_free().
514 	 */
515 	ASSERT0(DN_USED_BYTES(dn->dn_phys));
516 	ASSERT(BP_IS_HOLE(dn->dn_phys->dn_blkptr));
517 
518 	dnode_undirty_dbufs(&dn->dn_dirty_records[txgoff]);
519 	dnode_evict_dbufs(dn);
520 
521 	/*
522 	 * XXX - It would be nice to assert this, but we may still
523 	 * have residual holds from async evictions from the arc...
524 	 *
525 	 * zfs_obj_to_path() also depends on this being
526 	 * commented out.
527 	 *
528 	 * ASSERT3U(refcount_count(&dn->dn_holds), ==, 1);
529 	 */
530 
531 	/* Undirty next bits */
532 	dn->dn_next_nlevels[txgoff] = 0;
533 	dn->dn_next_indblkshift[txgoff] = 0;
534 	dn->dn_next_blksz[txgoff] = 0;
535 
536 	/* ASSERT(blkptrs are zero); */
537 	ASSERT(dn->dn_phys->dn_type != DMU_OT_NONE);
538 	ASSERT(dn->dn_type != DMU_OT_NONE);
539 
540 	ASSERT(dn->dn_free_txg > 0);
541 	if (dn->dn_allocated_txg != dn->dn_free_txg)
542 		dmu_buf_will_dirty(&dn->dn_dbuf->db, tx);
543 	bzero(dn->dn_phys, sizeof (dnode_phys_t));
544 
545 	mutex_enter(&dn->dn_mtx);
546 	dn->dn_type = DMU_OT_NONE;
547 	dn->dn_maxblkid = 0;
548 	dn->dn_allocated_txg = 0;
549 	dn->dn_free_txg = 0;
550 	dn->dn_have_spill = B_FALSE;
551 	mutex_exit(&dn->dn_mtx);
552 
553 	ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
554 
555 	dnode_rele(dn, (void *)(uintptr_t)tx->tx_txg);
556 	/*
557 	 * Now that we've released our hold, the dnode may
558 	 * be evicted, so we musn't access it.
559 	 */
560 }
561 
562 /*
563  * Write out the dnode's dirty buffers.
564  */
565 void
566 dnode_sync(dnode_t *dn, dmu_tx_t *tx)
567 {
568 	dnode_phys_t *dnp = dn->dn_phys;
569 	int txgoff = tx->tx_txg & TXG_MASK;
570 	list_t *list = &dn->dn_dirty_records[txgoff];
571 	static const dnode_phys_t zerodn = { 0 };
572 	boolean_t kill_spill = B_FALSE;
573 
574 	ASSERT(dmu_tx_is_syncing(tx));
575 	ASSERT(dnp->dn_type != DMU_OT_NONE || dn->dn_allocated_txg);
576 	ASSERT(dnp->dn_type != DMU_OT_NONE ||
577 	    bcmp(dnp, &zerodn, DNODE_SIZE) == 0);
578 	DNODE_VERIFY(dn);
579 
580 	ASSERT(dn->dn_dbuf == NULL || arc_released(dn->dn_dbuf->db_buf));
581 
582 	if (dmu_objset_userused_enabled(dn->dn_objset) &&
583 	    !DMU_OBJECT_IS_SPECIAL(dn->dn_object)) {
584 		mutex_enter(&dn->dn_mtx);
585 		dn->dn_oldused = DN_USED_BYTES(dn->dn_phys);
586 		dn->dn_oldflags = dn->dn_phys->dn_flags;
587 		dn->dn_phys->dn_flags |= DNODE_FLAG_USERUSED_ACCOUNTED;
588 		mutex_exit(&dn->dn_mtx);
589 		dmu_objset_userquota_get_ids(dn, B_FALSE, tx);
590 	} else {
591 		/* Once we account for it, we should always account for it. */
592 		ASSERT(!(dn->dn_phys->dn_flags &
593 		    DNODE_FLAG_USERUSED_ACCOUNTED));
594 	}
595 
596 	mutex_enter(&dn->dn_mtx);
597 	if (dn->dn_allocated_txg == tx->tx_txg) {
598 		/* The dnode is newly allocated or reallocated */
599 		if (dnp->dn_type == DMU_OT_NONE) {
600 			/* this is a first alloc, not a realloc */
601 			dnp->dn_nlevels = 1;
602 			dnp->dn_nblkptr = dn->dn_nblkptr;
603 		}
604 
605 		dnp->dn_type = dn->dn_type;
606 		dnp->dn_bonustype = dn->dn_bonustype;
607 		dnp->dn_bonuslen = dn->dn_bonuslen;
608 	}
609 	ASSERT(dnp->dn_nlevels > 1 ||
610 	    BP_IS_HOLE(&dnp->dn_blkptr[0]) ||
611 	    BP_IS_EMBEDDED(&dnp->dn_blkptr[0]) ||
612 	    BP_GET_LSIZE(&dnp->dn_blkptr[0]) ==
613 	    dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT);
614 	ASSERT(dnp->dn_nlevels < 2 ||
615 	    BP_IS_HOLE(&dnp->dn_blkptr[0]) ||
616 	    BP_GET_LSIZE(&dnp->dn_blkptr[0]) == 1 << dnp->dn_indblkshift);
617 
618 	if (dn->dn_next_type[txgoff] != 0) {
619 		dnp->dn_type = dn->dn_type;
620 		dn->dn_next_type[txgoff] = 0;
621 	}
622 
623 	if (dn->dn_next_blksz[txgoff] != 0) {
624 		ASSERT(P2PHASE(dn->dn_next_blksz[txgoff],
625 		    SPA_MINBLOCKSIZE) == 0);
626 		ASSERT(BP_IS_HOLE(&dnp->dn_blkptr[0]) ||
627 		    dn->dn_maxblkid == 0 || list_head(list) != NULL ||
628 		    dn->dn_next_blksz[txgoff] >> SPA_MINBLOCKSHIFT ==
629 		    dnp->dn_datablkszsec ||
630 		    !range_tree_is_empty(dn->dn_free_ranges[txgoff]));
631 		dnp->dn_datablkszsec =
632 		    dn->dn_next_blksz[txgoff] >> SPA_MINBLOCKSHIFT;
633 		dn->dn_next_blksz[txgoff] = 0;
634 	}
635 
636 	if (dn->dn_next_bonuslen[txgoff] != 0) {
637 		if (dn->dn_next_bonuslen[txgoff] == DN_ZERO_BONUSLEN)
638 			dnp->dn_bonuslen = 0;
639 		else
640 			dnp->dn_bonuslen = dn->dn_next_bonuslen[txgoff];
641 		ASSERT(dnp->dn_bonuslen <= DN_MAX_BONUSLEN);
642 		dn->dn_next_bonuslen[txgoff] = 0;
643 	}
644 
645 	if (dn->dn_next_bonustype[txgoff] != 0) {
646 		ASSERT(DMU_OT_IS_VALID(dn->dn_next_bonustype[txgoff]));
647 		dnp->dn_bonustype = dn->dn_next_bonustype[txgoff];
648 		dn->dn_next_bonustype[txgoff] = 0;
649 	}
650 
651 	boolean_t freeing_dnode = dn->dn_free_txg > 0 &&
652 	    dn->dn_free_txg <= tx->tx_txg;
653 
654 	/*
655 	 * Remove the spill block if we have been explicitly asked to
656 	 * remove it, or if the object is being removed.
657 	 */
658 	if (dn->dn_rm_spillblk[txgoff] || freeing_dnode) {
659 		if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR)
660 			kill_spill = B_TRUE;
661 		dn->dn_rm_spillblk[txgoff] = 0;
662 	}
663 
664 	if (dn->dn_next_indblkshift[txgoff] != 0) {
665 		ASSERT(dnp->dn_nlevels == 1);
666 		dnp->dn_indblkshift = dn->dn_next_indblkshift[txgoff];
667 		dn->dn_next_indblkshift[txgoff] = 0;
668 	}
669 
670 	/*
671 	 * Just take the live (open-context) values for checksum and compress.
672 	 * Strictly speaking it's a future leak, but nothing bad happens if we
673 	 * start using the new checksum or compress algorithm a little early.
674 	 */
675 	dnp->dn_checksum = dn->dn_checksum;
676 	dnp->dn_compress = dn->dn_compress;
677 
678 	mutex_exit(&dn->dn_mtx);
679 
680 	if (kill_spill) {
681 		free_blocks(dn, &dn->dn_phys->dn_spill, 1, tx);
682 		mutex_enter(&dn->dn_mtx);
683 		dnp->dn_flags &= ~DNODE_FLAG_SPILL_BLKPTR;
684 		mutex_exit(&dn->dn_mtx);
685 	}
686 
687 	/* process all the "freed" ranges in the file */
688 	if (dn->dn_free_ranges[txgoff] != NULL) {
689 		dnode_sync_free_range_arg_t dsfra;
690 		dsfra.dsfra_dnode = dn;
691 		dsfra.dsfra_tx = tx;
692 		dsfra.dsfra_free_indirects = freeing_dnode;
693 		if (freeing_dnode) {
694 			ASSERT(range_tree_contains(dn->dn_free_ranges[txgoff],
695 			    0, dn->dn_maxblkid + 1));
696 		}
697 		mutex_enter(&dn->dn_mtx);
698 		range_tree_vacate(dn->dn_free_ranges[txgoff],
699 		    dnode_sync_free_range, &dsfra);
700 		range_tree_destroy(dn->dn_free_ranges[txgoff]);
701 		dn->dn_free_ranges[txgoff] = NULL;
702 		mutex_exit(&dn->dn_mtx);
703 	}
704 
705 	if (freeing_dnode) {
706 		dn->dn_objset->os_freed_dnodes++;
707 		dnode_sync_free(dn, tx);
708 		return;
709 	}
710 
711 	if (dn->dn_next_nlevels[txgoff]) {
712 		dnode_increase_indirection(dn, tx);
713 		dn->dn_next_nlevels[txgoff] = 0;
714 	}
715 
716 	if (dn->dn_next_nblkptr[txgoff]) {
717 		/* this should only happen on a realloc */
718 		ASSERT(dn->dn_allocated_txg == tx->tx_txg);
719 		if (dn->dn_next_nblkptr[txgoff] > dnp->dn_nblkptr) {
720 			/* zero the new blkptrs we are gaining */
721 			bzero(dnp->dn_blkptr + dnp->dn_nblkptr,
722 			    sizeof (blkptr_t) *
723 			    (dn->dn_next_nblkptr[txgoff] - dnp->dn_nblkptr));
724 #ifdef ZFS_DEBUG
725 		} else {
726 			int i;
727 			ASSERT(dn->dn_next_nblkptr[txgoff] < dnp->dn_nblkptr);
728 			/* the blkptrs we are losing better be unallocated */
729 			for (i = dn->dn_next_nblkptr[txgoff];
730 			    i < dnp->dn_nblkptr; i++)
731 				ASSERT(BP_IS_HOLE(&dnp->dn_blkptr[i]));
732 #endif
733 		}
734 		mutex_enter(&dn->dn_mtx);
735 		dnp->dn_nblkptr = dn->dn_next_nblkptr[txgoff];
736 		dn->dn_next_nblkptr[txgoff] = 0;
737 		mutex_exit(&dn->dn_mtx);
738 	}
739 
740 	dbuf_sync_list(list, dn->dn_phys->dn_nlevels - 1, tx);
741 
742 	if (!DMU_OBJECT_IS_SPECIAL(dn->dn_object)) {
743 		ASSERT3P(list_head(list), ==, NULL);
744 		dnode_rele(dn, (void *)(uintptr_t)tx->tx_txg);
745 	}
746 
747 	/*
748 	 * Although we have dropped our reference to the dnode, it
749 	 * can't be evicted until its written, and we haven't yet
750 	 * initiated the IO for the dnode's dbuf.
751 	 */
752 }
753