xref: /titanic_51/usr/src/uts/common/fs/zfs/dnode.c (revision 843e19887f64dde75055cf8842fc4db2171eff45)
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 2007 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_impl.h>
33 #include <sys/dmu_tx.h>
34 #include <sys/dmu_objset.h>
35 #include <sys/dsl_dir.h>
36 #include <sys/dsl_dataset.h>
37 #include <sys/spa.h>
38 #include <sys/zio.h>
39 #include <sys/dmu_zfetch.h>
40 
41 static int free_range_compar(const void *node1, const void *node2);
42 
43 static kmem_cache_t *dnode_cache;
44 
45 static dnode_phys_t dnode_phys_zero;
46 
47 int zfs_default_bs = SPA_MINBLOCKSHIFT;
48 int zfs_default_ibs = DN_MAX_INDBLKSHIFT;
49 
50 /* ARGSUSED */
51 static int
52 dnode_cons(void *arg, void *unused, int kmflag)
53 {
54 	int i;
55 	dnode_t *dn = arg;
56 	bzero(dn, sizeof (dnode_t));
57 
58 	rw_init(&dn->dn_struct_rwlock, NULL, RW_DEFAULT, NULL);
59 	mutex_init(&dn->dn_mtx, NULL, MUTEX_DEFAULT, NULL);
60 	mutex_init(&dn->dn_dbufs_mtx, NULL, MUTEX_DEFAULT, NULL);
61 	refcount_create(&dn->dn_holds);
62 	refcount_create(&dn->dn_tx_holds);
63 
64 	for (i = 0; i < TXG_SIZE; i++) {
65 		avl_create(&dn->dn_ranges[i], free_range_compar,
66 		    sizeof (free_range_t),
67 		    offsetof(struct free_range, fr_node));
68 		list_create(&dn->dn_dirty_records[i],
69 		    sizeof (dbuf_dirty_record_t),
70 		    offsetof(dbuf_dirty_record_t, dr_dirty_node));
71 	}
72 
73 	list_create(&dn->dn_dbufs, sizeof (dmu_buf_impl_t),
74 	    offsetof(dmu_buf_impl_t, db_link));
75 
76 	return (0);
77 }
78 
79 /* ARGSUSED */
80 static void
81 dnode_dest(void *arg, void *unused)
82 {
83 	int i;
84 	dnode_t *dn = arg;
85 
86 	rw_destroy(&dn->dn_struct_rwlock);
87 	mutex_destroy(&dn->dn_mtx);
88 	mutex_destroy(&dn->dn_dbufs_mtx);
89 	refcount_destroy(&dn->dn_holds);
90 	refcount_destroy(&dn->dn_tx_holds);
91 
92 	for (i = 0; i < TXG_SIZE; i++) {
93 		avl_destroy(&dn->dn_ranges[i]);
94 		list_destroy(&dn->dn_dirty_records[i]);
95 	}
96 
97 	list_destroy(&dn->dn_dbufs);
98 }
99 
100 void
101 dnode_init(void)
102 {
103 	dnode_cache = kmem_cache_create("dnode_t",
104 	    sizeof (dnode_t),
105 	    0, dnode_cons, dnode_dest, NULL, NULL, NULL, 0);
106 }
107 
108 void
109 dnode_fini(void)
110 {
111 	kmem_cache_destroy(dnode_cache);
112 }
113 
114 
115 #ifdef ZFS_DEBUG
116 void
117 dnode_verify(dnode_t *dn)
118 {
119 	int drop_struct_lock = FALSE;
120 
121 	ASSERT(dn->dn_phys);
122 	ASSERT(dn->dn_objset);
123 
124 	ASSERT(dn->dn_phys->dn_type < DMU_OT_NUMTYPES);
125 
126 	if (!(zfs_flags & ZFS_DEBUG_DNODE_VERIFY))
127 		return;
128 
129 	if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
130 		rw_enter(&dn->dn_struct_rwlock, RW_READER);
131 		drop_struct_lock = TRUE;
132 	}
133 	if (dn->dn_phys->dn_type != DMU_OT_NONE || dn->dn_allocated_txg != 0) {
134 		int i;
135 		ASSERT3U(dn->dn_indblkshift, >=, 0);
136 		ASSERT3U(dn->dn_indblkshift, <=, SPA_MAXBLOCKSHIFT);
137 		if (dn->dn_datablkshift) {
138 			ASSERT3U(dn->dn_datablkshift, >=, SPA_MINBLOCKSHIFT);
139 			ASSERT3U(dn->dn_datablkshift, <=, SPA_MAXBLOCKSHIFT);
140 			ASSERT3U(1<<dn->dn_datablkshift, ==, dn->dn_datablksz);
141 		}
142 		ASSERT3U(dn->dn_nlevels, <=, 30);
143 		ASSERT3U(dn->dn_type, <=, DMU_OT_NUMTYPES);
144 		ASSERT3U(dn->dn_nblkptr, >=, 1);
145 		ASSERT3U(dn->dn_nblkptr, <=, DN_MAX_NBLKPTR);
146 		ASSERT3U(dn->dn_bonuslen, <=, DN_MAX_BONUSLEN);
147 		ASSERT3U(dn->dn_datablksz, ==,
148 		    dn->dn_datablkszsec << SPA_MINBLOCKSHIFT);
149 		ASSERT3U(ISP2(dn->dn_datablksz), ==, dn->dn_datablkshift != 0);
150 		ASSERT3U((dn->dn_nblkptr - 1) * sizeof (blkptr_t) +
151 		    dn->dn_bonuslen, <=, DN_MAX_BONUSLEN);
152 		for (i = 0; i < TXG_SIZE; i++) {
153 			ASSERT3U(dn->dn_next_nlevels[i], <=, dn->dn_nlevels);
154 		}
155 	}
156 	if (dn->dn_phys->dn_type != DMU_OT_NONE)
157 		ASSERT3U(dn->dn_phys->dn_nlevels, <=, dn->dn_nlevels);
158 	ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT || dn->dn_dbuf != NULL);
159 	if (dn->dn_dbuf != NULL) {
160 		ASSERT3P(dn->dn_phys, ==,
161 		    (dnode_phys_t *)dn->dn_dbuf->db.db_data +
162 		    (dn->dn_object % (dn->dn_dbuf->db.db_size >> DNODE_SHIFT)));
163 	}
164 	if (drop_struct_lock)
165 		rw_exit(&dn->dn_struct_rwlock);
166 }
167 #endif
168 
169 void
170 dnode_byteswap(dnode_phys_t *dnp)
171 {
172 	uint64_t *buf64 = (void*)&dnp->dn_blkptr;
173 	int i;
174 
175 	if (dnp->dn_type == DMU_OT_NONE) {
176 		bzero(dnp, sizeof (dnode_phys_t));
177 		return;
178 	}
179 
180 	dnp->dn_datablkszsec = BSWAP_16(dnp->dn_datablkszsec);
181 	dnp->dn_bonuslen = BSWAP_16(dnp->dn_bonuslen);
182 	dnp->dn_maxblkid = BSWAP_64(dnp->dn_maxblkid);
183 	dnp->dn_used = BSWAP_64(dnp->dn_used);
184 
185 	/*
186 	 * dn_nblkptr is only one byte, so it's OK to read it in either
187 	 * byte order.  We can't read dn_bouslen.
188 	 */
189 	ASSERT(dnp->dn_indblkshift <= SPA_MAXBLOCKSHIFT);
190 	ASSERT(dnp->dn_nblkptr <= DN_MAX_NBLKPTR);
191 	for (i = 0; i < dnp->dn_nblkptr * sizeof (blkptr_t)/8; i++)
192 		buf64[i] = BSWAP_64(buf64[i]);
193 
194 	/*
195 	 * OK to check dn_bonuslen for zero, because it won't matter if
196 	 * we have the wrong byte order.  This is necessary because the
197 	 * dnode dnode is smaller than a regular dnode.
198 	 */
199 	if (dnp->dn_bonuslen != 0) {
200 		/*
201 		 * Note that the bonus length calculated here may be
202 		 * longer than the actual bonus buffer.  This is because
203 		 * we always put the bonus buffer after the last block
204 		 * pointer (instead of packing it against the end of the
205 		 * dnode buffer).
206 		 */
207 		int off = (dnp->dn_nblkptr-1) * sizeof (blkptr_t);
208 		size_t len = DN_MAX_BONUSLEN - off;
209 		ASSERT3U(dnp->dn_bonustype, <, DMU_OT_NUMTYPES);
210 		dmu_ot[dnp->dn_bonustype].ot_byteswap(dnp->dn_bonus + off, len);
211 	}
212 }
213 
214 void
215 dnode_buf_byteswap(void *vbuf, size_t size)
216 {
217 	dnode_phys_t *buf = vbuf;
218 	int i;
219 
220 	ASSERT3U(sizeof (dnode_phys_t), ==, (1<<DNODE_SHIFT));
221 	ASSERT((size & (sizeof (dnode_phys_t)-1)) == 0);
222 
223 	size >>= DNODE_SHIFT;
224 	for (i = 0; i < size; i++) {
225 		dnode_byteswap(buf);
226 		buf++;
227 	}
228 }
229 
230 static int
231 free_range_compar(const void *node1, const void *node2)
232 {
233 	const free_range_t *rp1 = node1;
234 	const free_range_t *rp2 = node2;
235 
236 	if (rp1->fr_blkid < rp2->fr_blkid)
237 		return (-1);
238 	else if (rp1->fr_blkid > rp2->fr_blkid)
239 		return (1);
240 	else return (0);
241 }
242 
243 void
244 dnode_setbonuslen(dnode_t *dn, int newsize, dmu_tx_t *tx)
245 {
246 	ASSERT3U(refcount_count(&dn->dn_holds), >=, 1);
247 
248 	dnode_setdirty(dn, tx);
249 	rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
250 	ASSERT3U(newsize, <=, DN_MAX_BONUSLEN -
251 	    (dn->dn_nblkptr-1) * sizeof (blkptr_t));
252 	dn->dn_bonuslen = newsize;
253 	if (newsize == 0)
254 		dn->dn_next_bonuslen[tx->tx_txg & TXG_MASK] = DN_ZERO_BONUSLEN;
255 	else
256 		dn->dn_next_bonuslen[tx->tx_txg & TXG_MASK] = dn->dn_bonuslen;
257 	rw_exit(&dn->dn_struct_rwlock);
258 }
259 
260 static void
261 dnode_setdblksz(dnode_t *dn, int size)
262 {
263 	ASSERT3U(P2PHASE(size, SPA_MINBLOCKSIZE), ==, 0);
264 	ASSERT3U(size, <=, SPA_MAXBLOCKSIZE);
265 	ASSERT3U(size, >=, SPA_MINBLOCKSIZE);
266 	ASSERT3U(size >> SPA_MINBLOCKSHIFT, <,
267 	    1<<(sizeof (dn->dn_phys->dn_datablkszsec) * 8));
268 	dn->dn_datablksz = size;
269 	dn->dn_datablkszsec = size >> SPA_MINBLOCKSHIFT;
270 	dn->dn_datablkshift = ISP2(size) ? highbit(size - 1) : 0;
271 }
272 
273 static dnode_t *
274 dnode_create(objset_impl_t *os, dnode_phys_t *dnp, dmu_buf_impl_t *db,
275     uint64_t object)
276 {
277 	dnode_t *dn = kmem_cache_alloc(dnode_cache, KM_SLEEP);
278 	(void) dnode_cons(dn, NULL, 0); /* XXX */
279 
280 	dn->dn_objset = os;
281 	dn->dn_object = object;
282 	dn->dn_dbuf = db;
283 	dn->dn_phys = dnp;
284 
285 	if (dnp->dn_datablkszsec)
286 		dnode_setdblksz(dn, dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT);
287 	dn->dn_indblkshift = dnp->dn_indblkshift;
288 	dn->dn_nlevels = dnp->dn_nlevels;
289 	dn->dn_type = dnp->dn_type;
290 	dn->dn_nblkptr = dnp->dn_nblkptr;
291 	dn->dn_checksum = dnp->dn_checksum;
292 	dn->dn_compress = dnp->dn_compress;
293 	dn->dn_bonustype = dnp->dn_bonustype;
294 	dn->dn_bonuslen = dnp->dn_bonuslen;
295 	dn->dn_maxblkid = dnp->dn_maxblkid;
296 
297 	dmu_zfetch_init(&dn->dn_zfetch, dn);
298 
299 	ASSERT(dn->dn_phys->dn_type < DMU_OT_NUMTYPES);
300 	mutex_enter(&os->os_lock);
301 	list_insert_head(&os->os_dnodes, dn);
302 	mutex_exit(&os->os_lock);
303 
304 	arc_space_consume(sizeof (dnode_t));
305 	return (dn);
306 }
307 
308 static void
309 dnode_destroy(dnode_t *dn)
310 {
311 	objset_impl_t *os = dn->dn_objset;
312 
313 #ifdef ZFS_DEBUG
314 	int i;
315 
316 	for (i = 0; i < TXG_SIZE; i++) {
317 		ASSERT(!list_link_active(&dn->dn_dirty_link[i]));
318 		ASSERT(NULL == list_head(&dn->dn_dirty_records[i]));
319 		ASSERT(0 == avl_numnodes(&dn->dn_ranges[i]));
320 	}
321 	ASSERT(NULL == list_head(&dn->dn_dbufs));
322 #endif
323 
324 	mutex_enter(&os->os_lock);
325 	list_remove(&os->os_dnodes, dn);
326 	mutex_exit(&os->os_lock);
327 
328 	if (dn->dn_dirtyctx_firstset) {
329 		kmem_free(dn->dn_dirtyctx_firstset, 1);
330 		dn->dn_dirtyctx_firstset = NULL;
331 	}
332 	dmu_zfetch_rele(&dn->dn_zfetch);
333 	if (dn->dn_bonus) {
334 		mutex_enter(&dn->dn_bonus->db_mtx);
335 		dbuf_evict(dn->dn_bonus);
336 		dn->dn_bonus = NULL;
337 	}
338 	kmem_cache_free(dnode_cache, dn);
339 	arc_space_return(sizeof (dnode_t));
340 }
341 
342 void
343 dnode_allocate(dnode_t *dn, dmu_object_type_t ot, int blocksize, int ibs,
344     dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
345 {
346 	int i;
347 
348 	if (blocksize == 0)
349 		blocksize = 1 << zfs_default_bs;
350 	else if (blocksize > SPA_MAXBLOCKSIZE)
351 		blocksize = SPA_MAXBLOCKSIZE;
352 	else
353 		blocksize = P2ROUNDUP(blocksize, SPA_MINBLOCKSIZE);
354 
355 	if (ibs == 0)
356 		ibs = zfs_default_ibs;
357 
358 	ibs = MIN(MAX(ibs, DN_MIN_INDBLKSHIFT), DN_MAX_INDBLKSHIFT);
359 
360 	dprintf("os=%p obj=%llu txg=%llu blocksize=%d ibs=%d\n", dn->dn_objset,
361 	    dn->dn_object, tx->tx_txg, blocksize, ibs);
362 
363 	ASSERT(dn->dn_type == DMU_OT_NONE);
364 	ASSERT(bcmp(dn->dn_phys, &dnode_phys_zero, sizeof (dnode_phys_t)) == 0);
365 	ASSERT(dn->dn_phys->dn_type == DMU_OT_NONE);
366 	ASSERT(ot != DMU_OT_NONE);
367 	ASSERT3U(ot, <, DMU_OT_NUMTYPES);
368 	ASSERT((bonustype == DMU_OT_NONE && bonuslen == 0) ||
369 	    (bonustype != DMU_OT_NONE && bonuslen != 0));
370 	ASSERT3U(bonustype, <, DMU_OT_NUMTYPES);
371 	ASSERT3U(bonuslen, <=, DN_MAX_BONUSLEN);
372 	ASSERT(dn->dn_type == DMU_OT_NONE);
373 	ASSERT3U(dn->dn_maxblkid, ==, 0);
374 	ASSERT3U(dn->dn_allocated_txg, ==, 0);
375 	ASSERT3U(dn->dn_assigned_txg, ==, 0);
376 	ASSERT(refcount_is_zero(&dn->dn_tx_holds));
377 	ASSERT3U(refcount_count(&dn->dn_holds), <=, 1);
378 	ASSERT3P(list_head(&dn->dn_dbufs), ==, NULL);
379 
380 	for (i = 0; i < TXG_SIZE; i++) {
381 		ASSERT3U(dn->dn_next_nlevels[i], ==, 0);
382 		ASSERT3U(dn->dn_next_indblkshift[i], ==, 0);
383 		ASSERT3U(dn->dn_next_bonuslen[i], ==, 0);
384 		ASSERT3U(dn->dn_next_blksz[i], ==, 0);
385 		ASSERT(!list_link_active(&dn->dn_dirty_link[i]));
386 		ASSERT3P(list_head(&dn->dn_dirty_records[i]), ==, NULL);
387 		ASSERT3U(avl_numnodes(&dn->dn_ranges[i]), ==, 0);
388 	}
389 
390 	dn->dn_type = ot;
391 	dnode_setdblksz(dn, blocksize);
392 	dn->dn_indblkshift = ibs;
393 	dn->dn_nlevels = 1;
394 	dn->dn_nblkptr = 1 + ((DN_MAX_BONUSLEN - bonuslen) >> SPA_BLKPTRSHIFT);
395 	dn->dn_bonustype = bonustype;
396 	dn->dn_bonuslen = bonuslen;
397 	dn->dn_checksum = ZIO_CHECKSUM_INHERIT;
398 	dn->dn_compress = ZIO_COMPRESS_INHERIT;
399 	dn->dn_dirtyctx = 0;
400 
401 	dn->dn_free_txg = 0;
402 	if (dn->dn_dirtyctx_firstset) {
403 		kmem_free(dn->dn_dirtyctx_firstset, 1);
404 		dn->dn_dirtyctx_firstset = NULL;
405 	}
406 
407 	dn->dn_allocated_txg = tx->tx_txg;
408 
409 	dnode_setdirty(dn, tx);
410 	dn->dn_next_indblkshift[tx->tx_txg & TXG_MASK] = ibs;
411 	dn->dn_next_bonuslen[tx->tx_txg & TXG_MASK] = dn->dn_bonuslen;
412 	dn->dn_next_blksz[tx->tx_txg & TXG_MASK] = dn->dn_datablksz;
413 }
414 
415 void
416 dnode_reallocate(dnode_t *dn, dmu_object_type_t ot, int blocksize,
417     dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
418 {
419 	int i, old_nblkptr;
420 	dmu_buf_impl_t *db = NULL;
421 
422 	ASSERT3U(blocksize, >=, SPA_MINBLOCKSIZE);
423 	ASSERT3U(blocksize, <=, SPA_MAXBLOCKSIZE);
424 	ASSERT3U(blocksize % SPA_MINBLOCKSIZE, ==, 0);
425 	ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT || dmu_tx_private_ok(tx));
426 	ASSERT(tx->tx_txg != 0);
427 	ASSERT((bonustype == DMU_OT_NONE && bonuslen == 0) ||
428 	    (bonustype != DMU_OT_NONE && bonuslen != 0));
429 	ASSERT3U(bonustype, <, DMU_OT_NUMTYPES);
430 	ASSERT3U(bonuslen, <=, DN_MAX_BONUSLEN);
431 
432 	for (i = 0; i < TXG_SIZE; i++)
433 		ASSERT(!list_link_active(&dn->dn_dirty_link[i]));
434 
435 	/* clean up any unreferenced dbufs */
436 	dnode_evict_dbufs(dn);
437 	ASSERT3P(list_head(&dn->dn_dbufs), ==, NULL);
438 
439 	/*
440 	 * XXX I should really have a generation number to tell if we
441 	 * need to do this...
442 	 */
443 	if (blocksize != dn->dn_datablksz ||
444 	    dn->dn_bonustype != bonustype || dn->dn_bonuslen != bonuslen) {
445 		/* free all old data */
446 		dnode_free_range(dn, 0, -1ULL, tx);
447 	}
448 
449 	/* change blocksize */
450 	rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
451 	if (blocksize != dn->dn_datablksz &&
452 	    (!BP_IS_HOLE(&dn->dn_phys->dn_blkptr[0]) ||
453 	    list_head(&dn->dn_dbufs) != NULL)) {
454 		db = dbuf_hold(dn, 0, FTAG);
455 		dbuf_new_size(db, blocksize, tx);
456 	}
457 	dnode_setdblksz(dn, blocksize);
458 	dnode_setdirty(dn, tx);
459 	dn->dn_next_bonuslen[tx->tx_txg&TXG_MASK] = bonuslen;
460 	dn->dn_next_blksz[tx->tx_txg&TXG_MASK] = blocksize;
461 	rw_exit(&dn->dn_struct_rwlock);
462 	if (db)
463 		dbuf_rele(db, FTAG);
464 
465 	/* change type */
466 	dn->dn_type = ot;
467 
468 	/* change bonus size and type */
469 	mutex_enter(&dn->dn_mtx);
470 	old_nblkptr = dn->dn_nblkptr;
471 	dn->dn_bonustype = bonustype;
472 	dn->dn_bonuslen = bonuslen;
473 	dn->dn_nblkptr = 1 + ((DN_MAX_BONUSLEN - bonuslen) >> SPA_BLKPTRSHIFT);
474 	dn->dn_checksum = ZIO_CHECKSUM_INHERIT;
475 	dn->dn_compress = ZIO_COMPRESS_INHERIT;
476 	ASSERT3U(dn->dn_nblkptr, <=, DN_MAX_NBLKPTR);
477 
478 	/* XXX - for now, we can't make nblkptr smaller */
479 	ASSERT3U(dn->dn_nblkptr, >=, old_nblkptr);
480 
481 	/* fix up the bonus db_size if dn_nblkptr has changed */
482 	if (dn->dn_bonus && dn->dn_bonuslen != old_nblkptr) {
483 		dn->dn_bonus->db.db_size =
484 		    DN_MAX_BONUSLEN - (dn->dn_nblkptr-1) * sizeof (blkptr_t);
485 		ASSERT(dn->dn_bonuslen <= dn->dn_bonus->db.db_size);
486 	}
487 
488 	dn->dn_allocated_txg = tx->tx_txg;
489 	mutex_exit(&dn->dn_mtx);
490 }
491 
492 void
493 dnode_special_close(dnode_t *dn)
494 {
495 	/*
496 	 * Wait for final references to the dnode to clear.  This can
497 	 * only happen if the arc is asyncronously evicting state that
498 	 * has a hold on this dnode while we are trying to evict this
499 	 * dnode.
500 	 */
501 	while (refcount_count(&dn->dn_holds) > 0)
502 		delay(1);
503 	dnode_destroy(dn);
504 }
505 
506 dnode_t *
507 dnode_special_open(objset_impl_t *os, dnode_phys_t *dnp, uint64_t object)
508 {
509 	dnode_t *dn = dnode_create(os, dnp, NULL, object);
510 	DNODE_VERIFY(dn);
511 	return (dn);
512 }
513 
514 static void
515 dnode_buf_pageout(dmu_buf_t *db, void *arg)
516 {
517 	dnode_t **children_dnodes = arg;
518 	int i;
519 	int epb = db->db_size >> DNODE_SHIFT;
520 
521 	for (i = 0; i < epb; i++) {
522 		dnode_t *dn = children_dnodes[i];
523 		int n;
524 
525 		if (dn == NULL)
526 			continue;
527 #ifdef ZFS_DEBUG
528 		/*
529 		 * If there are holds on this dnode, then there should
530 		 * be holds on the dnode's containing dbuf as well; thus
531 		 * it wouldn't be eligable for eviction and this function
532 		 * would not have been called.
533 		 */
534 		ASSERT(refcount_is_zero(&dn->dn_holds));
535 		ASSERT(list_head(&dn->dn_dbufs) == NULL);
536 		ASSERT(refcount_is_zero(&dn->dn_tx_holds));
537 
538 		for (n = 0; n < TXG_SIZE; n++)
539 			ASSERT(!list_link_active(&dn->dn_dirty_link[n]));
540 #endif
541 		children_dnodes[i] = NULL;
542 		dnode_destroy(dn);
543 	}
544 	kmem_free(children_dnodes, epb * sizeof (dnode_t *));
545 }
546 
547 /*
548  * errors:
549  * EINVAL - invalid object number.
550  * EIO - i/o error.
551  * succeeds even for free dnodes.
552  */
553 int
554 dnode_hold_impl(objset_impl_t *os, uint64_t object, int flag,
555     void *tag, dnode_t **dnp)
556 {
557 	int epb, idx, err;
558 	int drop_struct_lock = FALSE;
559 	int type;
560 	uint64_t blk;
561 	dnode_t *mdn, *dn;
562 	dmu_buf_impl_t *db;
563 	dnode_t **children_dnodes;
564 
565 	if (object == 0 || object >= DN_MAX_OBJECT)
566 		return (EINVAL);
567 
568 	mdn = os->os_meta_dnode;
569 
570 	DNODE_VERIFY(mdn);
571 
572 	if (!RW_WRITE_HELD(&mdn->dn_struct_rwlock)) {
573 		rw_enter(&mdn->dn_struct_rwlock, RW_READER);
574 		drop_struct_lock = TRUE;
575 	}
576 
577 	blk = dbuf_whichblock(mdn, object * sizeof (dnode_phys_t));
578 
579 	db = dbuf_hold(mdn, blk, FTAG);
580 	if (drop_struct_lock)
581 		rw_exit(&mdn->dn_struct_rwlock);
582 	if (db == NULL)
583 		return (EIO);
584 	err = dbuf_read(db, NULL, DB_RF_CANFAIL);
585 	if (err) {
586 		dbuf_rele(db, FTAG);
587 		return (err);
588 	}
589 
590 	ASSERT3U(db->db.db_size, >=, 1<<DNODE_SHIFT);
591 	epb = db->db.db_size >> DNODE_SHIFT;
592 
593 	idx = object & (epb-1);
594 
595 	children_dnodes = dmu_buf_get_user(&db->db);
596 	if (children_dnodes == NULL) {
597 		dnode_t **winner;
598 		children_dnodes = kmem_zalloc(epb * sizeof (dnode_t *),
599 		    KM_SLEEP);
600 		if (winner = dmu_buf_set_user(&db->db, children_dnodes, NULL,
601 		    dnode_buf_pageout)) {
602 			kmem_free(children_dnodes, epb * sizeof (dnode_t *));
603 			children_dnodes = winner;
604 		}
605 	}
606 
607 	if ((dn = children_dnodes[idx]) == NULL) {
608 		dnode_phys_t *dnp = (dnode_phys_t *)db->db.db_data+idx;
609 		dnode_t *winner;
610 
611 		dn = dnode_create(os, dnp, db, object);
612 		winner = atomic_cas_ptr(&children_dnodes[idx], NULL, dn);
613 		if (winner != NULL) {
614 			dnode_destroy(dn);
615 			dn = winner;
616 		}
617 	}
618 
619 	mutex_enter(&dn->dn_mtx);
620 	type = dn->dn_type;
621 	if (dn->dn_free_txg ||
622 	    ((flag & DNODE_MUST_BE_ALLOCATED) && type == DMU_OT_NONE) ||
623 	    ((flag & DNODE_MUST_BE_FREE) && type != DMU_OT_NONE)) {
624 		mutex_exit(&dn->dn_mtx);
625 		dbuf_rele(db, FTAG);
626 		return (type == DMU_OT_NONE ? ENOENT : EEXIST);
627 	}
628 	mutex_exit(&dn->dn_mtx);
629 
630 	if (refcount_add(&dn->dn_holds, tag) == 1)
631 		dbuf_add_ref(db, dn);
632 
633 	DNODE_VERIFY(dn);
634 	ASSERT3P(dn->dn_dbuf, ==, db);
635 	ASSERT3U(dn->dn_object, ==, object);
636 	dbuf_rele(db, FTAG);
637 
638 	*dnp = dn;
639 	return (0);
640 }
641 
642 /*
643  * Return held dnode if the object is allocated, NULL if not.
644  */
645 int
646 dnode_hold(objset_impl_t *os, uint64_t object, void *tag, dnode_t **dnp)
647 {
648 	return (dnode_hold_impl(os, object, DNODE_MUST_BE_ALLOCATED, tag, dnp));
649 }
650 
651 /*
652  * Can only add a reference if there is already at least one
653  * reference on the dnode.  Returns FALSE if unable to add a
654  * new reference.
655  */
656 boolean_t
657 dnode_add_ref(dnode_t *dn, void *tag)
658 {
659 	mutex_enter(&dn->dn_mtx);
660 	if (refcount_is_zero(&dn->dn_holds)) {
661 		mutex_exit(&dn->dn_mtx);
662 		return (FALSE);
663 	}
664 	VERIFY(1 < refcount_add(&dn->dn_holds, tag));
665 	mutex_exit(&dn->dn_mtx);
666 	return (TRUE);
667 }
668 
669 void
670 dnode_rele(dnode_t *dn, void *tag)
671 {
672 	uint64_t refs;
673 
674 	mutex_enter(&dn->dn_mtx);
675 	refs = refcount_remove(&dn->dn_holds, tag);
676 	mutex_exit(&dn->dn_mtx);
677 	/* NOTE: the DNODE_DNODE does not have a dn_dbuf */
678 	if (refs == 0 && dn->dn_dbuf)
679 		dbuf_rele(dn->dn_dbuf, dn);
680 }
681 
682 void
683 dnode_setdirty(dnode_t *dn, dmu_tx_t *tx)
684 {
685 	objset_impl_t *os = dn->dn_objset;
686 	uint64_t txg = tx->tx_txg;
687 
688 	if (dn->dn_object == DMU_META_DNODE_OBJECT)
689 		return;
690 
691 	DNODE_VERIFY(dn);
692 
693 #ifdef ZFS_DEBUG
694 	mutex_enter(&dn->dn_mtx);
695 	ASSERT(dn->dn_phys->dn_type || dn->dn_allocated_txg);
696 	/* ASSERT(dn->dn_free_txg == 0 || dn->dn_free_txg >= txg); */
697 	mutex_exit(&dn->dn_mtx);
698 #endif
699 
700 	mutex_enter(&os->os_lock);
701 
702 	/*
703 	 * If we are already marked dirty, we're done.
704 	 */
705 	if (list_link_active(&dn->dn_dirty_link[txg & TXG_MASK])) {
706 		mutex_exit(&os->os_lock);
707 		return;
708 	}
709 
710 	ASSERT(!refcount_is_zero(&dn->dn_holds) || list_head(&dn->dn_dbufs));
711 	ASSERT(dn->dn_datablksz != 0);
712 	ASSERT3U(dn->dn_next_bonuslen[txg&TXG_MASK], ==, 0);
713 	ASSERT3U(dn->dn_next_blksz[txg&TXG_MASK], ==, 0);
714 
715 	dprintf_ds(os->os_dsl_dataset, "obj=%llu txg=%llu\n",
716 	    dn->dn_object, txg);
717 
718 	if (dn->dn_free_txg > 0 && dn->dn_free_txg <= txg) {
719 		list_insert_tail(&os->os_free_dnodes[txg&TXG_MASK], dn);
720 	} else {
721 		list_insert_tail(&os->os_dirty_dnodes[txg&TXG_MASK], dn);
722 	}
723 
724 	mutex_exit(&os->os_lock);
725 
726 	/*
727 	 * The dnode maintains a hold on its containing dbuf as
728 	 * long as there are holds on it.  Each instantiated child
729 	 * dbuf maintaines a hold on the dnode.  When the last child
730 	 * drops its hold, the dnode will drop its hold on the
731 	 * containing dbuf. We add a "dirty hold" here so that the
732 	 * dnode will hang around after we finish processing its
733 	 * children.
734 	 */
735 	VERIFY(dnode_add_ref(dn, (void *)(uintptr_t)tx->tx_txg));
736 
737 	(void) dbuf_dirty(dn->dn_dbuf, tx);
738 
739 	dsl_dataset_dirty(os->os_dsl_dataset, tx);
740 }
741 
742 void
743 dnode_free(dnode_t *dn, dmu_tx_t *tx)
744 {
745 	int txgoff = tx->tx_txg & TXG_MASK;
746 
747 	dprintf("dn=%p txg=%llu\n", dn, tx->tx_txg);
748 
749 	/* we should be the only holder... hopefully */
750 	/* ASSERT3U(refcount_count(&dn->dn_holds), ==, 1); */
751 
752 	mutex_enter(&dn->dn_mtx);
753 	if (dn->dn_type == DMU_OT_NONE || dn->dn_free_txg) {
754 		mutex_exit(&dn->dn_mtx);
755 		return;
756 	}
757 	dn->dn_free_txg = tx->tx_txg;
758 	mutex_exit(&dn->dn_mtx);
759 
760 	/*
761 	 * If the dnode is already dirty, it needs to be moved from
762 	 * the dirty list to the free list.
763 	 */
764 	mutex_enter(&dn->dn_objset->os_lock);
765 	if (list_link_active(&dn->dn_dirty_link[txgoff])) {
766 		list_remove(&dn->dn_objset->os_dirty_dnodes[txgoff], dn);
767 		list_insert_tail(&dn->dn_objset->os_free_dnodes[txgoff], dn);
768 		mutex_exit(&dn->dn_objset->os_lock);
769 	} else {
770 		mutex_exit(&dn->dn_objset->os_lock);
771 		dnode_setdirty(dn, tx);
772 	}
773 }
774 
775 /*
776  * Try to change the block size for the indicated dnode.  This can only
777  * succeed if there are no blocks allocated or dirty beyond first block
778  */
779 int
780 dnode_set_blksz(dnode_t *dn, uint64_t size, int ibs, dmu_tx_t *tx)
781 {
782 	dmu_buf_impl_t *db, *db_next;
783 	int have_db0 = FALSE;
784 
785 	if (size == 0)
786 		size = SPA_MINBLOCKSIZE;
787 	if (size > SPA_MAXBLOCKSIZE)
788 		size = SPA_MAXBLOCKSIZE;
789 	else
790 		size = P2ROUNDUP(size, SPA_MINBLOCKSIZE);
791 
792 	if (ibs == dn->dn_indblkshift)
793 		ibs = 0;
794 
795 	if (size >> SPA_MINBLOCKSHIFT == dn->dn_datablkszsec && ibs == 0)
796 		return (0);
797 
798 	rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
799 
800 	/* Check for any allocated blocks beyond the first */
801 	if (dn->dn_phys->dn_maxblkid != 0)
802 		goto fail;
803 
804 	mutex_enter(&dn->dn_dbufs_mtx);
805 	for (db = list_head(&dn->dn_dbufs); db; db = db_next) {
806 		db_next = list_next(&dn->dn_dbufs, db);
807 
808 		if (db->db_blkid == 0) {
809 			have_db0 = TRUE;
810 		} else if (db->db_blkid != DB_BONUS_BLKID) {
811 			mutex_exit(&dn->dn_dbufs_mtx);
812 			goto fail;
813 		}
814 	}
815 	mutex_exit(&dn->dn_dbufs_mtx);
816 
817 	if (ibs && dn->dn_nlevels != 1)
818 		goto fail;
819 
820 	db = NULL;
821 	if (!BP_IS_HOLE(&dn->dn_phys->dn_blkptr[0]) || have_db0) {
822 		/* obtain the old block */
823 		db = dbuf_hold(dn, 0, FTAG);
824 		dbuf_new_size(db, size, tx);
825 	}
826 
827 	dnode_setdblksz(dn, size);
828 	dnode_setdirty(dn, tx);
829 	dn->dn_next_blksz[tx->tx_txg&TXG_MASK] = size;
830 	if (ibs) {
831 		dn->dn_indblkshift = ibs;
832 		dn->dn_next_indblkshift[tx->tx_txg&TXG_MASK] = ibs;
833 	}
834 
835 	if (db)
836 		dbuf_rele(db, FTAG);
837 
838 	rw_exit(&dn->dn_struct_rwlock);
839 	return (0);
840 
841 fail:
842 	rw_exit(&dn->dn_struct_rwlock);
843 	return (ENOTSUP);
844 }
845 
846 void
847 dnode_new_blkid(dnode_t *dn, uint64_t blkid, dmu_tx_t *tx)
848 {
849 	uint64_t txgoff = tx->tx_txg & TXG_MASK;
850 	int drop_struct_lock = FALSE;
851 	int epbs, new_nlevels;
852 	uint64_t sz;
853 
854 	ASSERT(blkid != DB_BONUS_BLKID);
855 
856 	if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
857 		rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
858 		drop_struct_lock = TRUE;
859 	}
860 
861 	if (blkid <= dn->dn_maxblkid)
862 		goto out;
863 
864 	dn->dn_maxblkid = blkid;
865 
866 	/*
867 	 * Compute the number of levels necessary to support the new maxblkid.
868 	 */
869 	new_nlevels = 1;
870 	epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
871 	for (sz = dn->dn_nblkptr;
872 	    sz <= blkid && sz >= dn->dn_nblkptr; sz <<= epbs)
873 		new_nlevels++;
874 
875 	if (new_nlevels > dn->dn_nlevels) {
876 		int old_nlevels = dn->dn_nlevels;
877 		dmu_buf_impl_t *db;
878 		list_t *list;
879 		dbuf_dirty_record_t *new, *dr, *dr_next;
880 
881 		dn->dn_nlevels = new_nlevels;
882 
883 		ASSERT3U(new_nlevels, >, dn->dn_next_nlevels[txgoff]);
884 		dn->dn_next_nlevels[txgoff] = new_nlevels;
885 
886 		/* dirty the left indirects */
887 		db = dbuf_hold_level(dn, old_nlevels, 0, FTAG);
888 		new = dbuf_dirty(db, tx);
889 		dbuf_rele(db, FTAG);
890 
891 		/* transfer the dirty records to the new indirect */
892 		mutex_enter(&dn->dn_mtx);
893 		mutex_enter(&new->dt.di.dr_mtx);
894 		list = &dn->dn_dirty_records[txgoff];
895 		for (dr = list_head(list); dr; dr = dr_next) {
896 			dr_next = list_next(&dn->dn_dirty_records[txgoff], dr);
897 			if (dr->dr_dbuf->db_level != new_nlevels-1 &&
898 			    dr->dr_dbuf->db_blkid != DB_BONUS_BLKID) {
899 				ASSERT(dr->dr_dbuf->db_level == old_nlevels-1);
900 				list_remove(&dn->dn_dirty_records[txgoff], dr);
901 				list_insert_tail(&new->dt.di.dr_children, dr);
902 				dr->dr_parent = new;
903 			}
904 		}
905 		mutex_exit(&new->dt.di.dr_mtx);
906 		mutex_exit(&dn->dn_mtx);
907 	}
908 
909 out:
910 	if (drop_struct_lock)
911 		rw_exit(&dn->dn_struct_rwlock);
912 }
913 
914 void
915 dnode_clear_range(dnode_t *dn, uint64_t blkid, uint64_t nblks, dmu_tx_t *tx)
916 {
917 	avl_tree_t *tree = &dn->dn_ranges[tx->tx_txg&TXG_MASK];
918 	avl_index_t where;
919 	free_range_t *rp;
920 	free_range_t rp_tofind;
921 	uint64_t endblk = blkid + nblks;
922 
923 	ASSERT(MUTEX_HELD(&dn->dn_mtx));
924 	ASSERT(nblks <= UINT64_MAX - blkid); /* no overflow */
925 
926 	dprintf_dnode(dn, "blkid=%llu nblks=%llu txg=%llu\n",
927 	    blkid, nblks, tx->tx_txg);
928 	rp_tofind.fr_blkid = blkid;
929 	rp = avl_find(tree, &rp_tofind, &where);
930 	if (rp == NULL)
931 		rp = avl_nearest(tree, where, AVL_BEFORE);
932 	if (rp == NULL)
933 		rp = avl_nearest(tree, where, AVL_AFTER);
934 
935 	while (rp && (rp->fr_blkid <= blkid + nblks)) {
936 		uint64_t fr_endblk = rp->fr_blkid + rp->fr_nblks;
937 		free_range_t *nrp = AVL_NEXT(tree, rp);
938 
939 		if (blkid <= rp->fr_blkid && endblk >= fr_endblk) {
940 			/* clear this entire range */
941 			avl_remove(tree, rp);
942 			kmem_free(rp, sizeof (free_range_t));
943 		} else if (blkid <= rp->fr_blkid &&
944 		    endblk > rp->fr_blkid && endblk < fr_endblk) {
945 			/* clear the beginning of this range */
946 			rp->fr_blkid = endblk;
947 			rp->fr_nblks = fr_endblk - endblk;
948 		} else if (blkid > rp->fr_blkid && blkid < fr_endblk &&
949 		    endblk >= fr_endblk) {
950 			/* clear the end of this range */
951 			rp->fr_nblks = blkid - rp->fr_blkid;
952 		} else if (blkid > rp->fr_blkid && endblk < fr_endblk) {
953 			/* clear a chunk out of this range */
954 			free_range_t *new_rp =
955 			    kmem_alloc(sizeof (free_range_t), KM_SLEEP);
956 
957 			new_rp->fr_blkid = endblk;
958 			new_rp->fr_nblks = fr_endblk - endblk;
959 			avl_insert_here(tree, new_rp, rp, AVL_AFTER);
960 			rp->fr_nblks = blkid - rp->fr_blkid;
961 		}
962 		/* there may be no overlap */
963 		rp = nrp;
964 	}
965 }
966 
967 void
968 dnode_free_range(dnode_t *dn, uint64_t off, uint64_t len, dmu_tx_t *tx)
969 {
970 	dmu_buf_impl_t *db;
971 	uint64_t blkoff, blkid, nblks;
972 	int blksz, head;
973 	int trunc = FALSE;
974 
975 	rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
976 	blksz = dn->dn_datablksz;
977 
978 	/* If the range is past the end of the file, this is a no-op */
979 	if (off >= blksz * (dn->dn_maxblkid+1))
980 		goto out;
981 	if (len == -1ULL) {
982 		len = UINT64_MAX - off;
983 		trunc = TRUE;
984 	}
985 
986 	/*
987 	 * First, block align the region to free:
988 	 */
989 	if (ISP2(blksz)) {
990 		head = P2NPHASE(off, blksz);
991 		blkoff = P2PHASE(off, blksz);
992 	} else {
993 		ASSERT(dn->dn_maxblkid == 0);
994 		if (off == 0 && len >= blksz) {
995 			/* Freeing the whole block; don't do any head. */
996 			head = 0;
997 		} else {
998 			/* Freeing part of the block. */
999 			head = blksz - off;
1000 			ASSERT3U(head, >, 0);
1001 		}
1002 		blkoff = off;
1003 	}
1004 	/* zero out any partial block data at the start of the range */
1005 	if (head) {
1006 		ASSERT3U(blkoff + head, ==, blksz);
1007 		if (len < head)
1008 			head = len;
1009 		if (dbuf_hold_impl(dn, 0, dbuf_whichblock(dn, off), TRUE,
1010 		    FTAG, &db) == 0) {
1011 			caddr_t data;
1012 
1013 			/* don't dirty if it isn't on disk and isn't dirty */
1014 			if (db->db_last_dirty ||
1015 			    (db->db_blkptr && !BP_IS_HOLE(db->db_blkptr))) {
1016 				rw_exit(&dn->dn_struct_rwlock);
1017 				dbuf_will_dirty(db, tx);
1018 				rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
1019 				data = db->db.db_data;
1020 				bzero(data + blkoff, head);
1021 			}
1022 			dbuf_rele(db, FTAG);
1023 		}
1024 		off += head;
1025 		len -= head;
1026 	}
1027 
1028 	/* If the range was less than one block, we're done */
1029 	if (len == 0 || off >= blksz * (dn->dn_maxblkid+1))
1030 		goto out;
1031 
1032 	if (!ISP2(blksz)) {
1033 		/*
1034 		 * They are freeing the whole block of a
1035 		 * non-power-of-two blocksize file.  Skip all the messy
1036 		 * math.
1037 		 */
1038 		ASSERT3U(off, ==, 0);
1039 		ASSERT3U(len, >=, blksz);
1040 		blkid = 0;
1041 		nblks = 1;
1042 	} else {
1043 		int tail;
1044 		int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1045 		int blkshift = dn->dn_datablkshift;
1046 
1047 		/* If the remaining range is past end of file, we're done */
1048 		if (off > dn->dn_maxblkid << blkshift)
1049 			goto out;
1050 
1051 		if (off + len == UINT64_MAX)
1052 			tail = 0;
1053 		else
1054 			tail = P2PHASE(len, blksz);
1055 
1056 		ASSERT3U(P2PHASE(off, blksz), ==, 0);
1057 		/* zero out any partial block data at the end of the range */
1058 		if (tail) {
1059 			if (len < tail)
1060 				tail = len;
1061 			if (dbuf_hold_impl(dn, 0, dbuf_whichblock(dn, off+len),
1062 			    TRUE, FTAG, &db) == 0) {
1063 				/* don't dirty if not on disk and not dirty */
1064 				if (db->db_last_dirty ||
1065 				    (db->db_blkptr &&
1066 				    !BP_IS_HOLE(db->db_blkptr))) {
1067 					rw_exit(&dn->dn_struct_rwlock);
1068 					dbuf_will_dirty(db, tx);
1069 					rw_enter(&dn->dn_struct_rwlock,
1070 					    RW_WRITER);
1071 					bzero(db->db.db_data, tail);
1072 				}
1073 				dbuf_rele(db, FTAG);
1074 			}
1075 			len -= tail;
1076 		}
1077 		/* If the range did not include a full block, we are done */
1078 		if (len == 0)
1079 			goto out;
1080 
1081 		/* dirty the left indirects */
1082 		if (dn->dn_nlevels > 1 && off != 0) {
1083 			db = dbuf_hold_level(dn, 1,
1084 			    (off - head) >> (blkshift + epbs), FTAG);
1085 			dbuf_will_dirty(db, tx);
1086 			dbuf_rele(db, FTAG);
1087 		}
1088 
1089 		/* dirty the right indirects */
1090 		if (dn->dn_nlevels > 1 && !trunc) {
1091 			db = dbuf_hold_level(dn, 1,
1092 			    (off + len + tail - 1) >> (blkshift + epbs), FTAG);
1093 			dbuf_will_dirty(db, tx);
1094 			dbuf_rele(db, FTAG);
1095 		}
1096 
1097 		/*
1098 		 * Finally, add this range to the dnode range list, we
1099 		 * will finish up this free operation in the syncing phase.
1100 		 */
1101 		ASSERT(IS_P2ALIGNED(off, 1<<blkshift));
1102 		ASSERT(off + len == UINT64_MAX ||
1103 		    IS_P2ALIGNED(len, 1<<blkshift));
1104 		blkid = off >> blkshift;
1105 		nblks = len >> blkshift;
1106 
1107 		if (trunc)
1108 			dn->dn_maxblkid = (blkid ? blkid - 1 : 0);
1109 	}
1110 
1111 	mutex_enter(&dn->dn_mtx);
1112 	dnode_clear_range(dn, blkid, nblks, tx);
1113 	{
1114 		free_range_t *rp, *found;
1115 		avl_index_t where;
1116 		avl_tree_t *tree = &dn->dn_ranges[tx->tx_txg&TXG_MASK];
1117 
1118 		/* Add new range to dn_ranges */
1119 		rp = kmem_alloc(sizeof (free_range_t), KM_SLEEP);
1120 		rp->fr_blkid = blkid;
1121 		rp->fr_nblks = nblks;
1122 		found = avl_find(tree, rp, &where);
1123 		ASSERT(found == NULL);
1124 		avl_insert(tree, rp, where);
1125 		dprintf_dnode(dn, "blkid=%llu nblks=%llu txg=%llu\n",
1126 		    blkid, nblks, tx->tx_txg);
1127 	}
1128 	mutex_exit(&dn->dn_mtx);
1129 
1130 	dbuf_free_range(dn, blkid, nblks, tx);
1131 	dnode_setdirty(dn, tx);
1132 out:
1133 	rw_exit(&dn->dn_struct_rwlock);
1134 }
1135 
1136 /* return TRUE if this blkid was freed in a recent txg, or FALSE if it wasn't */
1137 uint64_t
1138 dnode_block_freed(dnode_t *dn, uint64_t blkid)
1139 {
1140 	free_range_t range_tofind;
1141 	void *dp = spa_get_dsl(dn->dn_objset->os_spa);
1142 	int i;
1143 
1144 	if (blkid == DB_BONUS_BLKID)
1145 		return (FALSE);
1146 
1147 	/*
1148 	 * If we're in the process of opening the pool, dp will not be
1149 	 * set yet, but there shouldn't be anything dirty.
1150 	 */
1151 	if (dp == NULL)
1152 		return (FALSE);
1153 
1154 	if (dn->dn_free_txg)
1155 		return (TRUE);
1156 
1157 	/*
1158 	 * If dn_datablkshift is not set, then there's only a single
1159 	 * block, in which case there will never be a free range so it
1160 	 * won't matter.
1161 	 */
1162 	range_tofind.fr_blkid = blkid;
1163 	mutex_enter(&dn->dn_mtx);
1164 	for (i = 0; i < TXG_SIZE; i++) {
1165 		free_range_t *range_found;
1166 		avl_index_t idx;
1167 
1168 		range_found = avl_find(&dn->dn_ranges[i], &range_tofind, &idx);
1169 		if (range_found) {
1170 			ASSERT(range_found->fr_nblks > 0);
1171 			break;
1172 		}
1173 		range_found = avl_nearest(&dn->dn_ranges[i], idx, AVL_BEFORE);
1174 		if (range_found &&
1175 		    range_found->fr_blkid + range_found->fr_nblks > blkid)
1176 			break;
1177 	}
1178 	mutex_exit(&dn->dn_mtx);
1179 	return (i < TXG_SIZE);
1180 }
1181 
1182 /* call from syncing context when we actually write/free space for this dnode */
1183 void
1184 dnode_diduse_space(dnode_t *dn, int64_t delta)
1185 {
1186 	uint64_t space;
1187 	dprintf_dnode(dn, "dn=%p dnp=%p used=%llu delta=%lld\n",
1188 	    dn, dn->dn_phys,
1189 	    (u_longlong_t)dn->dn_phys->dn_used,
1190 	    (longlong_t)delta);
1191 
1192 	mutex_enter(&dn->dn_mtx);
1193 	space = DN_USED_BYTES(dn->dn_phys);
1194 	if (delta > 0) {
1195 		ASSERT3U(space + delta, >=, space); /* no overflow */
1196 	} else {
1197 		ASSERT3U(space, >=, -delta); /* no underflow */
1198 	}
1199 	space += delta;
1200 	if (spa_version(dn->dn_objset->os_spa) < SPA_VERSION_DNODE_BYTES) {
1201 		ASSERT((dn->dn_phys->dn_flags & DNODE_FLAG_USED_BYTES) == 0);
1202 		ASSERT3U(P2PHASE(space, 1<<DEV_BSHIFT), ==, 0);
1203 		dn->dn_phys->dn_used = space >> DEV_BSHIFT;
1204 	} else {
1205 		dn->dn_phys->dn_used = space;
1206 		dn->dn_phys->dn_flags |= DNODE_FLAG_USED_BYTES;
1207 	}
1208 	mutex_exit(&dn->dn_mtx);
1209 }
1210 
1211 /*
1212  * Call when we think we're going to write/free space in open context.
1213  * Be conservative (ie. OK to write less than this or free more than
1214  * this, but don't write more or free less).
1215  */
1216 void
1217 dnode_willuse_space(dnode_t *dn, int64_t space, dmu_tx_t *tx)
1218 {
1219 	objset_impl_t *os = dn->dn_objset;
1220 	dsl_dataset_t *ds = os->os_dsl_dataset;
1221 
1222 	if (space > 0)
1223 		space = spa_get_asize(os->os_spa, space);
1224 
1225 	if (ds)
1226 		dsl_dir_willuse_space(ds->ds_dir, space, tx);
1227 
1228 	dmu_tx_willuse_space(tx, space);
1229 }
1230 
1231 static int
1232 dnode_next_offset_level(dnode_t *dn, boolean_t hole, uint64_t *offset,
1233 	int lvl, uint64_t blkfill, uint64_t txg)
1234 {
1235 	dmu_buf_impl_t *db = NULL;
1236 	void *data = NULL;
1237 	uint64_t epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
1238 	uint64_t epb = 1ULL << epbs;
1239 	uint64_t minfill, maxfill;
1240 	int i, error, span;
1241 
1242 	dprintf("probing object %llu offset %llx level %d of %u\n",
1243 	    dn->dn_object, *offset, lvl, dn->dn_phys->dn_nlevels);
1244 
1245 	if (lvl == dn->dn_phys->dn_nlevels) {
1246 		error = 0;
1247 		epb = dn->dn_phys->dn_nblkptr;
1248 		data = dn->dn_phys->dn_blkptr;
1249 	} else {
1250 		uint64_t blkid = dbuf_whichblock(dn, *offset) >> (epbs * lvl);
1251 		error = dbuf_hold_impl(dn, lvl, blkid, TRUE, FTAG, &db);
1252 		if (error) {
1253 			if (error == ENOENT)
1254 				return (hole ? 0 : ESRCH);
1255 			return (error);
1256 		}
1257 		error = dbuf_read(db, NULL, DB_RF_CANFAIL | DB_RF_HAVESTRUCT);
1258 		if (error) {
1259 			dbuf_rele(db, FTAG);
1260 			return (error);
1261 		}
1262 		data = db->db.db_data;
1263 	}
1264 
1265 	if (db && txg &&
1266 	    (db->db_blkptr == NULL || db->db_blkptr->blk_birth <= txg)) {
1267 		error = ESRCH;
1268 	} else if (lvl == 0) {
1269 		dnode_phys_t *dnp = data;
1270 		span = DNODE_SHIFT;
1271 		ASSERT(dn->dn_type == DMU_OT_DNODE);
1272 
1273 		for (i = (*offset >> span) & (blkfill - 1); i < blkfill; i++) {
1274 			boolean_t newcontents = B_TRUE;
1275 			if (txg) {
1276 				int j;
1277 				newcontents = B_FALSE;
1278 				for (j = 0; j < dnp[i].dn_nblkptr; j++) {
1279 					if (dnp[i].dn_blkptr[j].blk_birth > txg)
1280 						newcontents = B_TRUE;
1281 				}
1282 			}
1283 			if (!dnp[i].dn_type == hole && newcontents)
1284 				break;
1285 			*offset += 1ULL << span;
1286 		}
1287 		if (i == blkfill)
1288 			error = ESRCH;
1289 	} else {
1290 		blkptr_t *bp = data;
1291 		span = (lvl - 1) * epbs + dn->dn_datablkshift;
1292 		minfill = 0;
1293 		maxfill = blkfill << ((lvl - 1) * epbs);
1294 
1295 		if (hole)
1296 			maxfill--;
1297 		else
1298 			minfill++;
1299 
1300 		for (i = (*offset >> span) & ((1ULL << epbs) - 1);
1301 		    i < epb; i++) {
1302 			if (bp[i].blk_fill >= minfill &&
1303 			    bp[i].blk_fill <= maxfill &&
1304 			    bp[i].blk_birth > txg)
1305 				break;
1306 			*offset += 1ULL << span;
1307 		}
1308 		if (i >= epb)
1309 			error = ESRCH;
1310 	}
1311 
1312 	if (db)
1313 		dbuf_rele(db, FTAG);
1314 
1315 	return (error);
1316 }
1317 
1318 /*
1319  * Find the next hole, data, or sparse region at or after *offset.
1320  * The value 'blkfill' tells us how many items we expect to find
1321  * in an L0 data block; this value is 1 for normal objects,
1322  * DNODES_PER_BLOCK for the meta dnode, and some fraction of
1323  * DNODES_PER_BLOCK when searching for sparse regions thereof.
1324  *
1325  * Examples:
1326  *
1327  * dnode_next_offset(dn, hole, offset, 1, 1, 0);
1328  *	Finds the next hole/data in a file.
1329  *	Used in dmu_offset_next().
1330  *
1331  * dnode_next_offset(mdn, hole, offset, 0, DNODES_PER_BLOCK, txg);
1332  *	Finds the next free/allocated dnode an objset's meta-dnode.
1333  *	Only finds objects that have new contents since txg (ie.
1334  *	bonus buffer changes and content removal are ignored).
1335  *	Used in dmu_object_next().
1336  *
1337  * dnode_next_offset(mdn, TRUE, offset, 2, DNODES_PER_BLOCK >> 2, 0);
1338  *	Finds the next L2 meta-dnode bp that's at most 1/4 full.
1339  *	Used in dmu_object_alloc().
1340  */
1341 int
1342 dnode_next_offset(dnode_t *dn, boolean_t hole, uint64_t *offset,
1343     int minlvl, uint64_t blkfill, uint64_t txg)
1344 {
1345 	int lvl, maxlvl;
1346 	int error = 0;
1347 	uint64_t initial_offset = *offset;
1348 
1349 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
1350 
1351 	if (dn->dn_phys->dn_nlevels == 0) {
1352 		rw_exit(&dn->dn_struct_rwlock);
1353 		return (ESRCH);
1354 	}
1355 
1356 	if (dn->dn_datablkshift == 0) {
1357 		if (*offset < dn->dn_datablksz) {
1358 			if (hole)
1359 				*offset = dn->dn_datablksz;
1360 		} else {
1361 			error = ESRCH;
1362 		}
1363 		rw_exit(&dn->dn_struct_rwlock);
1364 		return (error);
1365 	}
1366 
1367 	maxlvl = dn->dn_phys->dn_nlevels;
1368 
1369 	for (lvl = minlvl; lvl <= maxlvl; lvl++) {
1370 		error = dnode_next_offset_level(dn,
1371 		    hole, offset, lvl, blkfill, txg);
1372 		if (error != ESRCH)
1373 			break;
1374 	}
1375 
1376 	while (--lvl >= minlvl && error == 0) {
1377 		error = dnode_next_offset_level(dn,
1378 		    hole, offset, lvl, blkfill, txg);
1379 	}
1380 
1381 	rw_exit(&dn->dn_struct_rwlock);
1382 
1383 	if (error == 0 && initial_offset > *offset)
1384 		error = ESRCH;
1385 
1386 	return (error);
1387 }
1388