xref: /titanic_41/usr/src/uts/common/fs/zfs/dnode_sync.c (revision 159d09a20817016f09b3ea28d1bdada4a336bb91)
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 2008 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 #pragma ident	"%Z%%M%	%I%	%E% SMI"
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 
37 static void
38 dnode_increase_indirection(dnode_t *dn, dmu_tx_t *tx)
39 {
40 	dmu_buf_impl_t *db;
41 	int txgoff = tx->tx_txg & TXG_MASK;
42 	int nblkptr = dn->dn_phys->dn_nblkptr;
43 	int old_toplvl = dn->dn_phys->dn_nlevels - 1;
44 	int new_level = dn->dn_next_nlevels[txgoff];
45 	int i;
46 
47 	rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
48 
49 	/* this dnode can't be paged out because it's dirty */
50 	ASSERT(dn->dn_phys->dn_type != DMU_OT_NONE);
51 	ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
52 	ASSERT(new_level > 1 && dn->dn_phys->dn_nlevels > 0);
53 
54 	db = dbuf_hold_level(dn, dn->dn_phys->dn_nlevels, 0, FTAG);
55 	ASSERT(db != NULL);
56 
57 	dn->dn_phys->dn_nlevels = new_level;
58 	dprintf("os=%p obj=%llu, increase to %d\n", dn->dn_objset,
59 	    dn->dn_object, dn->dn_phys->dn_nlevels);
60 
61 	/* check for existing blkptrs in the dnode */
62 	for (i = 0; i < nblkptr; i++)
63 		if (!BP_IS_HOLE(&dn->dn_phys->dn_blkptr[i]))
64 			break;
65 	if (i != nblkptr) {
66 		/* transfer dnode's block pointers to new indirect block */
67 		(void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED|DB_RF_HAVESTRUCT);
68 		ASSERT(db->db.db_data);
69 		ASSERT(arc_released(db->db_buf));
70 		ASSERT3U(sizeof (blkptr_t) * nblkptr, <=, db->db.db_size);
71 		bcopy(dn->dn_phys->dn_blkptr, db->db.db_data,
72 		    sizeof (blkptr_t) * nblkptr);
73 		arc_buf_freeze(db->db_buf);
74 	}
75 
76 	/* set dbuf's parent pointers to new indirect buf */
77 	for (i = 0; i < nblkptr; i++) {
78 		dmu_buf_impl_t *child = dbuf_find(dn, old_toplvl, i);
79 
80 		if (child == NULL)
81 			continue;
82 		ASSERT3P(child->db_dnode, ==, dn);
83 		if (child->db_parent && child->db_parent != dn->dn_dbuf) {
84 			ASSERT(child->db_parent->db_level == db->db_level);
85 			ASSERT(child->db_blkptr !=
86 			    &dn->dn_phys->dn_blkptr[child->db_blkid]);
87 			mutex_exit(&child->db_mtx);
88 			continue;
89 		}
90 		ASSERT(child->db_parent == NULL ||
91 		    child->db_parent == dn->dn_dbuf);
92 
93 		child->db_parent = db;
94 		dbuf_add_ref(db, child);
95 		if (db->db.db_data)
96 			child->db_blkptr = (blkptr_t *)db->db.db_data + i;
97 		else
98 			child->db_blkptr = NULL;
99 		dprintf_dbuf_bp(child, child->db_blkptr,
100 		    "changed db_blkptr to new indirect %s", "");
101 
102 		mutex_exit(&child->db_mtx);
103 	}
104 
105 	bzero(dn->dn_phys->dn_blkptr, sizeof (blkptr_t) * nblkptr);
106 
107 	dbuf_rele(db, FTAG);
108 
109 	rw_exit(&dn->dn_struct_rwlock);
110 }
111 
112 static int
113 free_blocks(dnode_t *dn, blkptr_t *bp, int num, dmu_tx_t *tx)
114 {
115 	dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset;
116 	uint64_t bytesfreed = 0;
117 	int i, blocks_freed = 0;
118 
119 	dprintf("ds=%p obj=%llx num=%d\n", ds, dn->dn_object, num);
120 
121 	for (i = 0; i < num; i++, bp++) {
122 		if (BP_IS_HOLE(bp))
123 			continue;
124 
125 		bytesfreed += dsl_dataset_block_kill(ds, bp, dn->dn_zio, tx);
126 		ASSERT3U(bytesfreed, <=, DN_USED_BYTES(dn->dn_phys));
127 		bzero(bp, sizeof (blkptr_t));
128 		blocks_freed += 1;
129 	}
130 	dnode_diduse_space(dn, -bytesfreed);
131 	return (blocks_freed);
132 }
133 
134 #ifdef ZFS_DEBUG
135 static void
136 free_verify(dmu_buf_impl_t *db, uint64_t start, uint64_t end, dmu_tx_t *tx)
137 {
138 	int off, num;
139 	int i, err, epbs;
140 	uint64_t txg = tx->tx_txg;
141 
142 	epbs = db->db_dnode->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
143 	off = start - (db->db_blkid * 1<<epbs);
144 	num = end - start + 1;
145 
146 	ASSERT3U(off, >=, 0);
147 	ASSERT3U(num, >=, 0);
148 	ASSERT3U(db->db_level, >, 0);
149 	ASSERT3U(db->db.db_size, ==, 1<<db->db_dnode->dn_phys->dn_indblkshift);
150 	ASSERT3U(off+num, <=, db->db.db_size >> SPA_BLKPTRSHIFT);
151 	ASSERT(db->db_blkptr != NULL);
152 
153 	for (i = off; i < off+num; i++) {
154 		uint64_t *buf;
155 		dmu_buf_impl_t *child;
156 		dbuf_dirty_record_t *dr;
157 		int j;
158 
159 		ASSERT(db->db_level == 1);
160 
161 		rw_enter(&db->db_dnode->dn_struct_rwlock, RW_READER);
162 		err = dbuf_hold_impl(db->db_dnode, db->db_level-1,
163 		    (db->db_blkid << epbs) + i, TRUE, FTAG, &child);
164 		rw_exit(&db->db_dnode->dn_struct_rwlock);
165 		if (err == ENOENT)
166 			continue;
167 		ASSERT(err == 0);
168 		ASSERT(child->db_level == 0);
169 		dr = child->db_last_dirty;
170 		while (dr && dr->dr_txg > txg)
171 			dr = dr->dr_next;
172 		ASSERT(dr == NULL || dr->dr_txg == txg);
173 
174 		/* data_old better be zeroed */
175 		if (dr) {
176 			buf = dr->dt.dl.dr_data->b_data;
177 			for (j = 0; j < child->db.db_size >> 3; j++) {
178 				if (buf[j] != 0) {
179 					panic("freed data not zero: "
180 					    "child=%p i=%d off=%d num=%d\n",
181 					    (void *)child, i, off, num);
182 				}
183 			}
184 		}
185 
186 		/*
187 		 * db_data better be zeroed unless it's dirty in a
188 		 * future txg.
189 		 */
190 		mutex_enter(&child->db_mtx);
191 		buf = child->db.db_data;
192 		if (buf != NULL && child->db_state != DB_FILL &&
193 		    child->db_last_dirty == NULL) {
194 			for (j = 0; j < child->db.db_size >> 3; j++) {
195 				if (buf[j] != 0) {
196 					panic("freed data not zero: "
197 					    "child=%p i=%d off=%d num=%d\n",
198 					    (void *)child, i, off, num);
199 				}
200 			}
201 		}
202 		mutex_exit(&child->db_mtx);
203 
204 		dbuf_rele(child, FTAG);
205 	}
206 }
207 #endif
208 
209 #define	ALL -1
210 
211 static int
212 free_children(dmu_buf_impl_t *db, uint64_t blkid, uint64_t nblks, int trunc,
213     dmu_tx_t *tx)
214 {
215 	dnode_t *dn = db->db_dnode;
216 	blkptr_t *bp;
217 	dmu_buf_impl_t *subdb;
218 	uint64_t start, end, dbstart, dbend, i;
219 	int epbs, shift, err;
220 	int all = TRUE;
221 	int blocks_freed = 0;
222 
223 	/*
224 	 * There is a small possibility that this block will not be cached:
225 	 *   1 - if level > 1 and there are no children with level <= 1
226 	 *   2 - if we didn't get a dirty hold (because this block had just
227 	 *	 finished being written -- and so had no holds), and then this
228 	 *	 block got evicted before we got here.
229 	 */
230 	if (db->db_state != DB_CACHED)
231 		(void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED);
232 
233 	arc_release(db->db_buf, db);
234 	bp = (blkptr_t *)db->db.db_data;
235 
236 	epbs = db->db_dnode->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
237 	shift = (db->db_level - 1) * epbs;
238 	dbstart = db->db_blkid << epbs;
239 	start = blkid >> shift;
240 	if (dbstart < start) {
241 		bp += start - dbstart;
242 		all = FALSE;
243 	} else {
244 		start = dbstart;
245 	}
246 	dbend = ((db->db_blkid + 1) << epbs) - 1;
247 	end = (blkid + nblks - 1) >> shift;
248 	if (dbend <= end)
249 		end = dbend;
250 	else if (all)
251 		all = trunc;
252 	ASSERT3U(start, <=, end);
253 
254 	if (db->db_level == 1) {
255 		FREE_VERIFY(db, start, end, tx);
256 		blocks_freed = free_blocks(dn, bp, end-start+1, tx);
257 		arc_buf_freeze(db->db_buf);
258 		ASSERT(all || blocks_freed == 0 || db->db_last_dirty);
259 		return (all ? ALL : blocks_freed);
260 	}
261 
262 	for (i = start; i <= end; i++, bp++) {
263 		if (BP_IS_HOLE(bp))
264 			continue;
265 		rw_enter(&dn->dn_struct_rwlock, RW_READER);
266 		err = dbuf_hold_impl(dn, db->db_level-1, i, TRUE, FTAG, &subdb);
267 		ASSERT3U(err, ==, 0);
268 		rw_exit(&dn->dn_struct_rwlock);
269 
270 		if (free_children(subdb, blkid, nblks, trunc, tx) == ALL) {
271 			ASSERT3P(subdb->db_blkptr, ==, bp);
272 			blocks_freed += free_blocks(dn, bp, 1, tx);
273 		} else {
274 			all = FALSE;
275 		}
276 		dbuf_rele(subdb, FTAG);
277 	}
278 	arc_buf_freeze(db->db_buf);
279 #ifdef ZFS_DEBUG
280 	bp -= (end-start)+1;
281 	for (i = start; i <= end; i++, bp++) {
282 		if (i == start && blkid != 0)
283 			continue;
284 		else if (i == end && !trunc)
285 			continue;
286 		ASSERT3U(bp->blk_birth, ==, 0);
287 	}
288 #endif
289 	ASSERT(all || blocks_freed == 0 || db->db_last_dirty);
290 	return (all ? ALL : blocks_freed);
291 }
292 
293 /*
294  * free_range: Traverse the indicated range of the provided file
295  * and "free" all the blocks contained there.
296  */
297 static void
298 dnode_sync_free_range(dnode_t *dn, uint64_t blkid, uint64_t nblks, dmu_tx_t *tx)
299 {
300 	blkptr_t *bp = dn->dn_phys->dn_blkptr;
301 	dmu_buf_impl_t *db;
302 	int trunc, start, end, shift, i, err;
303 	int dnlevel = dn->dn_phys->dn_nlevels;
304 
305 	if (blkid > dn->dn_phys->dn_maxblkid)
306 		return;
307 
308 	ASSERT(dn->dn_phys->dn_maxblkid < UINT64_MAX);
309 	trunc = blkid + nblks > dn->dn_phys->dn_maxblkid;
310 	if (trunc)
311 		nblks = dn->dn_phys->dn_maxblkid - blkid + 1;
312 
313 	/* There are no indirect blocks in the object */
314 	if (dnlevel == 1) {
315 		if (blkid >= dn->dn_phys->dn_nblkptr) {
316 			/* this range was never made persistent */
317 			return;
318 		}
319 		ASSERT3U(blkid + nblks, <=, dn->dn_phys->dn_nblkptr);
320 		(void) free_blocks(dn, bp + blkid, nblks, tx);
321 		if (trunc) {
322 			uint64_t off = (dn->dn_phys->dn_maxblkid + 1) *
323 			    (dn->dn_phys->dn_datablkszsec << SPA_MINBLOCKSHIFT);
324 			dn->dn_phys->dn_maxblkid = (blkid ? blkid - 1 : 0);
325 			ASSERT(off < dn->dn_phys->dn_maxblkid ||
326 			    dn->dn_phys->dn_maxblkid == 0 ||
327 			    dnode_next_offset(dn, 0, &off, 1, 1, 0) != 0);
328 		}
329 		return;
330 	}
331 
332 	shift = (dnlevel - 1) * (dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT);
333 	start = blkid >> shift;
334 	ASSERT(start < dn->dn_phys->dn_nblkptr);
335 	end = (blkid + nblks - 1) >> shift;
336 	bp += start;
337 	for (i = start; i <= end; i++, bp++) {
338 		if (BP_IS_HOLE(bp))
339 			continue;
340 		rw_enter(&dn->dn_struct_rwlock, RW_READER);
341 		err = dbuf_hold_impl(dn, dnlevel-1, i, TRUE, FTAG, &db);
342 		ASSERT3U(err, ==, 0);
343 		rw_exit(&dn->dn_struct_rwlock);
344 
345 		if (free_children(db, blkid, nblks, trunc, tx) == ALL) {
346 			ASSERT3P(db->db_blkptr, ==, bp);
347 			(void) free_blocks(dn, bp, 1, tx);
348 		}
349 		dbuf_rele(db, FTAG);
350 	}
351 	if (trunc) {
352 		uint64_t off = (dn->dn_phys->dn_maxblkid + 1) *
353 		    (dn->dn_phys->dn_datablkszsec << SPA_MINBLOCKSHIFT);
354 		dn->dn_phys->dn_maxblkid = (blkid ? blkid - 1 : 0);
355 		ASSERT(off < dn->dn_phys->dn_maxblkid ||
356 		    dn->dn_phys->dn_maxblkid == 0 ||
357 		    dnode_next_offset(dn, 0, &off, 1, 1, 0) != 0);
358 	}
359 }
360 
361 /*
362  * Try to kick all the dnodes dbufs out of the cache...
363  */
364 void
365 dnode_evict_dbufs(dnode_t *dn)
366 {
367 	int progress;
368 	int pass = 0;
369 
370 	do {
371 		dmu_buf_impl_t *db, marker;
372 		int evicting = FALSE;
373 
374 		progress = FALSE;
375 		mutex_enter(&dn->dn_dbufs_mtx);
376 		list_insert_tail(&dn->dn_dbufs, &marker);
377 		db = list_head(&dn->dn_dbufs);
378 		for (; db != &marker; db = list_head(&dn->dn_dbufs)) {
379 			list_remove(&dn->dn_dbufs, db);
380 			list_insert_tail(&dn->dn_dbufs, db);
381 			ASSERT3P(db->db_dnode, ==, dn);
382 
383 			mutex_enter(&db->db_mtx);
384 			if (db->db_state == DB_EVICTING) {
385 				progress = TRUE;
386 				evicting = TRUE;
387 				mutex_exit(&db->db_mtx);
388 			} else if (refcount_is_zero(&db->db_holds)) {
389 				progress = TRUE;
390 				dbuf_clear(db); /* exits db_mtx for us */
391 			} else {
392 				mutex_exit(&db->db_mtx);
393 			}
394 
395 		}
396 		list_remove(&dn->dn_dbufs, &marker);
397 		/*
398 		 * NB: we need to drop dn_dbufs_mtx between passes so
399 		 * that any DB_EVICTING dbufs can make progress.
400 		 * Ideally, we would have some cv we could wait on, but
401 		 * since we don't, just wait a bit to give the other
402 		 * thread a chance to run.
403 		 */
404 		mutex_exit(&dn->dn_dbufs_mtx);
405 		if (evicting)
406 			delay(1);
407 		pass++;
408 		ASSERT(pass < 100); /* sanity check */
409 	} while (progress);
410 
411 	rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
412 	if (dn->dn_bonus && refcount_is_zero(&dn->dn_bonus->db_holds)) {
413 		mutex_enter(&dn->dn_bonus->db_mtx);
414 		dbuf_evict(dn->dn_bonus);
415 		dn->dn_bonus = NULL;
416 	}
417 	rw_exit(&dn->dn_struct_rwlock);
418 }
419 
420 static void
421 dnode_undirty_dbufs(list_t *list)
422 {
423 	dbuf_dirty_record_t *dr;
424 
425 	while (dr = list_head(list)) {
426 		dmu_buf_impl_t *db = dr->dr_dbuf;
427 		uint64_t txg = dr->dr_txg;
428 
429 		mutex_enter(&db->db_mtx);
430 		/* XXX - use dbuf_undirty()? */
431 		list_remove(list, dr);
432 		ASSERT(db->db_last_dirty == dr);
433 		db->db_last_dirty = NULL;
434 		db->db_dirtycnt -= 1;
435 		if (db->db_level == 0) {
436 			ASSERT(db->db_blkid == DB_BONUS_BLKID ||
437 			    dr->dt.dl.dr_data == db->db_buf);
438 			dbuf_unoverride(dr);
439 			mutex_exit(&db->db_mtx);
440 		} else {
441 			mutex_exit(&db->db_mtx);
442 			dnode_undirty_dbufs(&dr->dt.di.dr_children);
443 		}
444 		kmem_free(dr, sizeof (dbuf_dirty_record_t));
445 		dbuf_rele(db, (void *)(uintptr_t)txg);
446 	}
447 }
448 
449 static void
450 dnode_sync_free(dnode_t *dn, dmu_tx_t *tx)
451 {
452 	int txgoff = tx->tx_txg & TXG_MASK;
453 
454 	ASSERT(dmu_tx_is_syncing(tx));
455 
456 	/*
457 	 * Our contents should have been freed in dnode_sync() by the
458 	 * free range record inserted by the caller of dnode_free().
459 	 */
460 	ASSERT3U(DN_USED_BYTES(dn->dn_phys), ==, 0);
461 	ASSERT(BP_IS_HOLE(dn->dn_phys->dn_blkptr));
462 
463 	dnode_undirty_dbufs(&dn->dn_dirty_records[txgoff]);
464 	dnode_evict_dbufs(dn);
465 	ASSERT3P(list_head(&dn->dn_dbufs), ==, NULL);
466 
467 	/*
468 	 * XXX - It would be nice to assert this, but we may still
469 	 * have residual holds from async evictions from the arc...
470 	 *
471 	 * zfs_obj_to_path() also depends on this being
472 	 * commented out.
473 	 *
474 	 * ASSERT3U(refcount_count(&dn->dn_holds), ==, 1);
475 	 */
476 
477 	/* Undirty next bits */
478 	dn->dn_next_nlevels[txgoff] = 0;
479 	dn->dn_next_indblkshift[txgoff] = 0;
480 	dn->dn_next_blksz[txgoff] = 0;
481 
482 	/* ASSERT(blkptrs are zero); */
483 	ASSERT(dn->dn_phys->dn_type != DMU_OT_NONE);
484 	ASSERT(dn->dn_type != DMU_OT_NONE);
485 
486 	ASSERT(dn->dn_free_txg > 0);
487 	if (dn->dn_allocated_txg != dn->dn_free_txg)
488 		dbuf_will_dirty(dn->dn_dbuf, tx);
489 	bzero(dn->dn_phys, sizeof (dnode_phys_t));
490 
491 	mutex_enter(&dn->dn_mtx);
492 	dn->dn_type = DMU_OT_NONE;
493 	dn->dn_maxblkid = 0;
494 	dn->dn_allocated_txg = 0;
495 	dn->dn_free_txg = 0;
496 	mutex_exit(&dn->dn_mtx);
497 
498 	ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
499 
500 	dnode_rele(dn, (void *)(uintptr_t)tx->tx_txg);
501 	/*
502 	 * Now that we've released our hold, the dnode may
503 	 * be evicted, so we musn't access it.
504 	 */
505 }
506 
507 /*
508  * Write out the dnode's dirty buffers.
509  *
510  * NOTE: The dnode is kept in memory by being dirty.  Once the
511  * dirty bit is cleared, it may be evicted.  Beware of this!
512  */
513 void
514 dnode_sync(dnode_t *dn, dmu_tx_t *tx)
515 {
516 	free_range_t *rp;
517 	dnode_phys_t *dnp = dn->dn_phys;
518 	int txgoff = tx->tx_txg & TXG_MASK;
519 	list_t *list = &dn->dn_dirty_records[txgoff];
520 
521 	ASSERT(dmu_tx_is_syncing(tx));
522 	ASSERT(dnp->dn_type != DMU_OT_NONE || dn->dn_allocated_txg);
523 	DNODE_VERIFY(dn);
524 
525 	ASSERT(dn->dn_dbuf == NULL || arc_released(dn->dn_dbuf->db_buf));
526 
527 	mutex_enter(&dn->dn_mtx);
528 	if (dn->dn_allocated_txg == tx->tx_txg) {
529 		/* The dnode is newly allocated or reallocated */
530 		if (dnp->dn_type == DMU_OT_NONE) {
531 			/* this is a first alloc, not a realloc */
532 			/* XXX shouldn't the phys already be zeroed? */
533 			bzero(dnp, DNODE_CORE_SIZE);
534 			dnp->dn_nlevels = 1;
535 		}
536 
537 		if (dn->dn_nblkptr > dnp->dn_nblkptr) {
538 			/* zero the new blkptrs we are gaining */
539 			bzero(dnp->dn_blkptr + dnp->dn_nblkptr,
540 			    sizeof (blkptr_t) *
541 			    (dn->dn_nblkptr - dnp->dn_nblkptr));
542 		}
543 		dnp->dn_type = dn->dn_type;
544 		dnp->dn_bonustype = dn->dn_bonustype;
545 		dnp->dn_bonuslen = dn->dn_bonuslen;
546 		dnp->dn_nblkptr = dn->dn_nblkptr;
547 	}
548 
549 	ASSERT(dnp->dn_nlevels > 1 ||
550 	    BP_IS_HOLE(&dnp->dn_blkptr[0]) ||
551 	    BP_GET_LSIZE(&dnp->dn_blkptr[0]) ==
552 	    dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT);
553 
554 	if (dn->dn_next_blksz[txgoff]) {
555 		ASSERT(P2PHASE(dn->dn_next_blksz[txgoff],
556 		    SPA_MINBLOCKSIZE) == 0);
557 		ASSERT(BP_IS_HOLE(&dnp->dn_blkptr[0]) ||
558 		    dn->dn_maxblkid == 0 || list_head(list) != NULL ||
559 		    dn->dn_next_blksz[txgoff] >> SPA_MINBLOCKSHIFT ==
560 		    dnp->dn_datablkszsec);
561 		dnp->dn_datablkszsec =
562 		    dn->dn_next_blksz[txgoff] >> SPA_MINBLOCKSHIFT;
563 		dn->dn_next_blksz[txgoff] = 0;
564 	}
565 
566 	if (dn->dn_next_bonuslen[txgoff]) {
567 		if (dn->dn_next_bonuslen[txgoff] == DN_ZERO_BONUSLEN)
568 			dnp->dn_bonuslen = 0;
569 		else
570 			dnp->dn_bonuslen = dn->dn_next_bonuslen[txgoff];
571 		ASSERT(dnp->dn_bonuslen <= DN_MAX_BONUSLEN);
572 		dn->dn_next_bonuslen[txgoff] = 0;
573 	}
574 
575 	if (dn->dn_next_indblkshift[txgoff]) {
576 		ASSERT(dnp->dn_nlevels == 1);
577 		dnp->dn_indblkshift = dn->dn_next_indblkshift[txgoff];
578 		dn->dn_next_indblkshift[txgoff] = 0;
579 	}
580 
581 	/*
582 	 * Just take the live (open-context) values for checksum and compress.
583 	 * Strictly speaking it's a future leak, but nothing bad happens if we
584 	 * start using the new checksum or compress algorithm a little early.
585 	 */
586 	dnp->dn_checksum = dn->dn_checksum;
587 	dnp->dn_compress = dn->dn_compress;
588 
589 	mutex_exit(&dn->dn_mtx);
590 
591 	/* process all the "freed" ranges in the file */
592 	while (rp = avl_last(&dn->dn_ranges[txgoff])) {
593 		dnode_sync_free_range(dn, rp->fr_blkid, rp->fr_nblks, tx);
594 		/* grab the mutex so we don't race with dnode_block_freed() */
595 		mutex_enter(&dn->dn_mtx);
596 		avl_remove(&dn->dn_ranges[txgoff], rp);
597 		mutex_exit(&dn->dn_mtx);
598 		kmem_free(rp, sizeof (free_range_t));
599 	}
600 
601 	if (dn->dn_free_txg > 0 && dn->dn_free_txg <= tx->tx_txg) {
602 		dnode_sync_free(dn, tx);
603 		return;
604 	}
605 
606 	if (dn->dn_next_nlevels[txgoff]) {
607 		dnode_increase_indirection(dn, tx);
608 		dn->dn_next_nlevels[txgoff] = 0;
609 	}
610 
611 	dbuf_sync_list(list, tx);
612 
613 	if (dn->dn_object != DMU_META_DNODE_OBJECT) {
614 		ASSERT3P(list_head(list), ==, NULL);
615 		dnode_rele(dn, (void *)(uintptr_t)tx->tx_txg);
616 	}
617 
618 	/*
619 	 * Although we have dropped our reference to the dnode, it
620 	 * can't be evicted until its written, and we haven't yet
621 	 * initiated the IO for the dnode's dbuf.
622 	 */
623 }
624