xref: /titanic_44/usr/src/uts/common/fs/zfs/dmu.c (revision ae0476dbaa01cfe1e3f6783f2a62d23e26d53c7a)
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 2009 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 #include <sys/dmu.h>
27 #include <sys/dmu_impl.h>
28 #include <sys/dmu_tx.h>
29 #include <sys/dbuf.h>
30 #include <sys/dnode.h>
31 #include <sys/zfs_context.h>
32 #include <sys/dmu_objset.h>
33 #include <sys/dmu_traverse.h>
34 #include <sys/dsl_dataset.h>
35 #include <sys/dsl_dir.h>
36 #include <sys/dsl_pool.h>
37 #include <sys/dsl_synctask.h>
38 #include <sys/dsl_prop.h>
39 #include <sys/dmu_zfetch.h>
40 #include <sys/zfs_ioctl.h>
41 #include <sys/zap.h>
42 #include <sys/zio_checksum.h>
43 #ifdef _KERNEL
44 #include <sys/vmsystm.h>
45 #include <sys/zfs_znode.h>
46 #endif
47 
48 const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES] = {
49 	{	byteswap_uint8_array,	TRUE,	"unallocated"		},
50 	{	zap_byteswap,		TRUE,	"object directory"	},
51 	{	byteswap_uint64_array,	TRUE,	"object array"		},
52 	{	byteswap_uint8_array,	TRUE,	"packed nvlist"		},
53 	{	byteswap_uint64_array,	TRUE,	"packed nvlist size"	},
54 	{	byteswap_uint64_array,	TRUE,	"bplist"		},
55 	{	byteswap_uint64_array,	TRUE,	"bplist header"		},
56 	{	byteswap_uint64_array,	TRUE,	"SPA space map header"	},
57 	{	byteswap_uint64_array,	TRUE,	"SPA space map"		},
58 	{	byteswap_uint64_array,	TRUE,	"ZIL intent log"	},
59 	{	dnode_buf_byteswap,	TRUE,	"DMU dnode"		},
60 	{	dmu_objset_byteswap,	TRUE,	"DMU objset"		},
61 	{	byteswap_uint64_array,	TRUE,	"DSL directory"		},
62 	{	zap_byteswap,		TRUE,	"DSL directory child map"},
63 	{	zap_byteswap,		TRUE,	"DSL dataset snap map"	},
64 	{	zap_byteswap,		TRUE,	"DSL props"		},
65 	{	byteswap_uint64_array,	TRUE,	"DSL dataset"		},
66 	{	zfs_znode_byteswap,	TRUE,	"ZFS znode"		},
67 	{	zfs_oldacl_byteswap,	TRUE,	"ZFS V0 ACL"		},
68 	{	byteswap_uint8_array,	FALSE,	"ZFS plain file"	},
69 	{	zap_byteswap,		TRUE,	"ZFS directory"		},
70 	{	zap_byteswap,		TRUE,	"ZFS master node"	},
71 	{	zap_byteswap,		TRUE,	"ZFS delete queue"	},
72 	{	byteswap_uint8_array,	FALSE,	"zvol object"		},
73 	{	zap_byteswap,		TRUE,	"zvol prop"		},
74 	{	byteswap_uint8_array,	FALSE,	"other uint8[]"		},
75 	{	byteswap_uint64_array,	FALSE,	"other uint64[]"	},
76 	{	zap_byteswap,		TRUE,	"other ZAP"		},
77 	{	zap_byteswap,		TRUE,	"persistent error log"	},
78 	{	byteswap_uint8_array,	TRUE,	"SPA history"		},
79 	{	byteswap_uint64_array,	TRUE,	"SPA history offsets"	},
80 	{	zap_byteswap,		TRUE,	"Pool properties"	},
81 	{	zap_byteswap,		TRUE,	"DSL permissions"	},
82 	{	zfs_acl_byteswap,	TRUE,	"ZFS ACL"		},
83 	{	byteswap_uint8_array,	TRUE,	"ZFS SYSACL"		},
84 	{	byteswap_uint8_array,	TRUE,	"FUID table"		},
85 	{	byteswap_uint64_array,	TRUE,	"FUID table size"	},
86 	{	zap_byteswap,		TRUE,	"DSL dataset next clones"},
87 	{	zap_byteswap,		TRUE,	"scrub work queue"	},
88 	{	zap_byteswap,		TRUE,	"ZFS user/group used"	},
89 	{	zap_byteswap,		TRUE,	"ZFS user/group quota"	},
90 	{	zap_byteswap,		TRUE,	"snapshot refcount tags"},
91 	{	zap_byteswap,		TRUE,	"DDT ZAP algorithm"	},
92 	{	zap_byteswap,		TRUE,	"DDT statistics"	},
93 };
94 
95 int
96 dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
97     void *tag, dmu_buf_t **dbp)
98 {
99 	dnode_t *dn;
100 	uint64_t blkid;
101 	dmu_buf_impl_t *db;
102 	int err;
103 
104 	err = dnode_hold(os, object, FTAG, &dn);
105 	if (err)
106 		return (err);
107 	blkid = dbuf_whichblock(dn, offset);
108 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
109 	db = dbuf_hold(dn, blkid, tag);
110 	rw_exit(&dn->dn_struct_rwlock);
111 	if (db == NULL) {
112 		err = EIO;
113 	} else {
114 		err = dbuf_read(db, NULL, DB_RF_CANFAIL);
115 		if (err) {
116 			dbuf_rele(db, tag);
117 			db = NULL;
118 		}
119 	}
120 
121 	dnode_rele(dn, FTAG);
122 	*dbp = &db->db;
123 	return (err);
124 }
125 
126 int
127 dmu_bonus_max(void)
128 {
129 	return (DN_MAX_BONUSLEN);
130 }
131 
132 int
133 dmu_set_bonus(dmu_buf_t *db, int newsize, dmu_tx_t *tx)
134 {
135 	dnode_t *dn = ((dmu_buf_impl_t *)db)->db_dnode;
136 
137 	if (dn->dn_bonus != (dmu_buf_impl_t *)db)
138 		return (EINVAL);
139 	if (newsize < 0 || newsize > db->db_size)
140 		return (EINVAL);
141 	dnode_setbonuslen(dn, newsize, tx);
142 	return (0);
143 }
144 
145 /*
146  * returns ENOENT, EIO, or 0.
147  */
148 int
149 dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **dbp)
150 {
151 	dnode_t *dn;
152 	dmu_buf_impl_t *db;
153 	int error;
154 
155 	error = dnode_hold(os, object, FTAG, &dn);
156 	if (error)
157 		return (error);
158 
159 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
160 	if (dn->dn_bonus == NULL) {
161 		rw_exit(&dn->dn_struct_rwlock);
162 		rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
163 		if (dn->dn_bonus == NULL)
164 			dbuf_create_bonus(dn);
165 	}
166 	db = dn->dn_bonus;
167 	rw_exit(&dn->dn_struct_rwlock);
168 
169 	/* as long as the bonus buf is held, the dnode will be held */
170 	if (refcount_add(&db->db_holds, tag) == 1)
171 		VERIFY(dnode_add_ref(dn, db));
172 
173 	dnode_rele(dn, FTAG);
174 
175 	VERIFY(0 == dbuf_read(db, NULL, DB_RF_MUST_SUCCEED));
176 
177 	*dbp = &db->db;
178 	return (0);
179 }
180 
181 /*
182  * Note: longer-term, we should modify all of the dmu_buf_*() interfaces
183  * to take a held dnode rather than <os, object> -- the lookup is wasteful,
184  * and can induce severe lock contention when writing to several files
185  * whose dnodes are in the same block.
186  */
187 static int
188 dmu_buf_hold_array_by_dnode(dnode_t *dn, uint64_t offset, uint64_t length,
189     int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp, uint32_t flags)
190 {
191 	dsl_pool_t *dp = NULL;
192 	dmu_buf_t **dbp;
193 	uint64_t blkid, nblks, i;
194 	uint32_t dbuf_flags;
195 	int err;
196 	zio_t *zio;
197 	hrtime_t start;
198 
199 	ASSERT(length <= DMU_MAX_ACCESS);
200 
201 	dbuf_flags = DB_RF_CANFAIL | DB_RF_NEVERWAIT | DB_RF_HAVESTRUCT;
202 	if (flags & DMU_READ_NO_PREFETCH || length > zfetch_array_rd_sz)
203 		dbuf_flags |= DB_RF_NOPREFETCH;
204 
205 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
206 	if (dn->dn_datablkshift) {
207 		int blkshift = dn->dn_datablkshift;
208 		nblks = (P2ROUNDUP(offset+length, 1ULL<<blkshift) -
209 		    P2ALIGN(offset, 1ULL<<blkshift)) >> blkshift;
210 	} else {
211 		if (offset + length > dn->dn_datablksz) {
212 			zfs_panic_recover("zfs: accessing past end of object "
213 			    "%llx/%llx (size=%u access=%llu+%llu)",
214 			    (longlong_t)dn->dn_objset->
215 			    os_dsl_dataset->ds_object,
216 			    (longlong_t)dn->dn_object, dn->dn_datablksz,
217 			    (longlong_t)offset, (longlong_t)length);
218 			rw_exit(&dn->dn_struct_rwlock);
219 			return (EIO);
220 		}
221 		nblks = 1;
222 	}
223 	dbp = kmem_zalloc(sizeof (dmu_buf_t *) * nblks, KM_SLEEP);
224 
225 	if (dn->dn_objset->os_dsl_dataset)
226 		dp = dn->dn_objset->os_dsl_dataset->ds_dir->dd_pool;
227 	if (dp && dsl_pool_sync_context(dp))
228 		start = gethrtime();
229 	zio = zio_root(dn->dn_objset->os_spa, NULL, NULL, ZIO_FLAG_CANFAIL);
230 	blkid = dbuf_whichblock(dn, offset);
231 	for (i = 0; i < nblks; i++) {
232 		dmu_buf_impl_t *db = dbuf_hold(dn, blkid+i, tag);
233 		if (db == NULL) {
234 			rw_exit(&dn->dn_struct_rwlock);
235 			dmu_buf_rele_array(dbp, nblks, tag);
236 			zio_nowait(zio);
237 			return (EIO);
238 		}
239 		/* initiate async i/o */
240 		if (read) {
241 			(void) dbuf_read(db, zio, dbuf_flags);
242 		}
243 		dbp[i] = &db->db;
244 	}
245 	rw_exit(&dn->dn_struct_rwlock);
246 
247 	/* wait for async i/o */
248 	err = zio_wait(zio);
249 	/* track read overhead when we are in sync context */
250 	if (dp && dsl_pool_sync_context(dp))
251 		dp->dp_read_overhead += gethrtime() - start;
252 	if (err) {
253 		dmu_buf_rele_array(dbp, nblks, tag);
254 		return (err);
255 	}
256 
257 	/* wait for other io to complete */
258 	if (read) {
259 		for (i = 0; i < nblks; i++) {
260 			dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbp[i];
261 			mutex_enter(&db->db_mtx);
262 			while (db->db_state == DB_READ ||
263 			    db->db_state == DB_FILL)
264 				cv_wait(&db->db_changed, &db->db_mtx);
265 			if (db->db_state == DB_UNCACHED)
266 				err = EIO;
267 			mutex_exit(&db->db_mtx);
268 			if (err) {
269 				dmu_buf_rele_array(dbp, nblks, tag);
270 				return (err);
271 			}
272 		}
273 	}
274 
275 	*numbufsp = nblks;
276 	*dbpp = dbp;
277 	return (0);
278 }
279 
280 static int
281 dmu_buf_hold_array(objset_t *os, uint64_t object, uint64_t offset,
282     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
283 {
284 	dnode_t *dn;
285 	int err;
286 
287 	err = dnode_hold(os, object, FTAG, &dn);
288 	if (err)
289 		return (err);
290 
291 	err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
292 	    numbufsp, dbpp, DMU_READ_PREFETCH);
293 
294 	dnode_rele(dn, FTAG);
295 
296 	return (err);
297 }
298 
299 int
300 dmu_buf_hold_array_by_bonus(dmu_buf_t *db, uint64_t offset,
301     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
302 {
303 	dnode_t *dn = ((dmu_buf_impl_t *)db)->db_dnode;
304 	int err;
305 
306 	err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
307 	    numbufsp, dbpp, DMU_READ_PREFETCH);
308 
309 	return (err);
310 }
311 
312 void
313 dmu_buf_rele_array(dmu_buf_t **dbp_fake, int numbufs, void *tag)
314 {
315 	int i;
316 	dmu_buf_impl_t **dbp = (dmu_buf_impl_t **)dbp_fake;
317 
318 	if (numbufs == 0)
319 		return;
320 
321 	for (i = 0; i < numbufs; i++) {
322 		if (dbp[i])
323 			dbuf_rele(dbp[i], tag);
324 	}
325 
326 	kmem_free(dbp, sizeof (dmu_buf_t *) * numbufs);
327 }
328 
329 void
330 dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset, uint64_t len)
331 {
332 	dnode_t *dn;
333 	uint64_t blkid;
334 	int nblks, i, err;
335 
336 	if (zfs_prefetch_disable)
337 		return;
338 
339 	if (len == 0) {  /* they're interested in the bonus buffer */
340 		dn = os->os_meta_dnode;
341 
342 		if (object == 0 || object >= DN_MAX_OBJECT)
343 			return;
344 
345 		rw_enter(&dn->dn_struct_rwlock, RW_READER);
346 		blkid = dbuf_whichblock(dn, object * sizeof (dnode_phys_t));
347 		dbuf_prefetch(dn, blkid);
348 		rw_exit(&dn->dn_struct_rwlock);
349 		return;
350 	}
351 
352 	/*
353 	 * XXX - Note, if the dnode for the requested object is not
354 	 * already cached, we will do a *synchronous* read in the
355 	 * dnode_hold() call.  The same is true for any indirects.
356 	 */
357 	err = dnode_hold(os, object, FTAG, &dn);
358 	if (err != 0)
359 		return;
360 
361 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
362 	if (dn->dn_datablkshift) {
363 		int blkshift = dn->dn_datablkshift;
364 		nblks = (P2ROUNDUP(offset+len, 1<<blkshift) -
365 		    P2ALIGN(offset, 1<<blkshift)) >> blkshift;
366 	} else {
367 		nblks = (offset < dn->dn_datablksz);
368 	}
369 
370 	if (nblks != 0) {
371 		blkid = dbuf_whichblock(dn, offset);
372 		for (i = 0; i < nblks; i++)
373 			dbuf_prefetch(dn, blkid+i);
374 	}
375 
376 	rw_exit(&dn->dn_struct_rwlock);
377 
378 	dnode_rele(dn, FTAG);
379 }
380 
381 /*
382  * Get the next "chunk" of file data to free.  We traverse the file from
383  * the end so that the file gets shorter over time (if we crashes in the
384  * middle, this will leave us in a better state).  We find allocated file
385  * data by simply searching the allocated level 1 indirects.
386  */
387 static int
388 get_next_chunk(dnode_t *dn, uint64_t *start, uint64_t limit)
389 {
390 	uint64_t len = *start - limit;
391 	uint64_t blkcnt = 0;
392 	uint64_t maxblks = DMU_MAX_ACCESS / (1ULL << (dn->dn_indblkshift + 1));
393 	uint64_t iblkrange =
394 	    dn->dn_datablksz * EPB(dn->dn_indblkshift, SPA_BLKPTRSHIFT);
395 
396 	ASSERT(limit <= *start);
397 
398 	if (len <= iblkrange * maxblks) {
399 		*start = limit;
400 		return (0);
401 	}
402 	ASSERT(ISP2(iblkrange));
403 
404 	while (*start > limit && blkcnt < maxblks) {
405 		int err;
406 
407 		/* find next allocated L1 indirect */
408 		err = dnode_next_offset(dn,
409 		    DNODE_FIND_BACKWARDS, start, 2, 1, 0);
410 
411 		/* if there are no more, then we are done */
412 		if (err == ESRCH) {
413 			*start = limit;
414 			return (0);
415 		} else if (err) {
416 			return (err);
417 		}
418 		blkcnt += 1;
419 
420 		/* reset offset to end of "next" block back */
421 		*start = P2ALIGN(*start, iblkrange);
422 		if (*start <= limit)
423 			*start = limit;
424 		else
425 			*start -= 1;
426 	}
427 	return (0);
428 }
429 
430 static int
431 dmu_free_long_range_impl(objset_t *os, dnode_t *dn, uint64_t offset,
432     uint64_t length, boolean_t free_dnode)
433 {
434 	dmu_tx_t *tx;
435 	uint64_t object_size, start, end, len;
436 	boolean_t trunc = (length == DMU_OBJECT_END);
437 	int align, err;
438 
439 	align = 1 << dn->dn_datablkshift;
440 	ASSERT(align > 0);
441 	object_size = align == 1 ? dn->dn_datablksz :
442 	    (dn->dn_maxblkid + 1) << dn->dn_datablkshift;
443 
444 	end = offset + length;
445 	if (trunc || end > object_size)
446 		end = object_size;
447 	if (end <= offset)
448 		return (0);
449 	length = end - offset;
450 
451 	while (length) {
452 		start = end;
453 		/* assert(offset <= start) */
454 		err = get_next_chunk(dn, &start, offset);
455 		if (err)
456 			return (err);
457 		len = trunc ? DMU_OBJECT_END : end - start;
458 
459 		tx = dmu_tx_create(os);
460 		dmu_tx_hold_free(tx, dn->dn_object, start, len);
461 		err = dmu_tx_assign(tx, TXG_WAIT);
462 		if (err) {
463 			dmu_tx_abort(tx);
464 			return (err);
465 		}
466 
467 		dnode_free_range(dn, start, trunc ? -1 : len, tx);
468 
469 		if (start == 0 && free_dnode) {
470 			ASSERT(trunc);
471 			dnode_free(dn, tx);
472 		}
473 
474 		length -= end - start;
475 
476 		dmu_tx_commit(tx);
477 		end = start;
478 	}
479 	return (0);
480 }
481 
482 int
483 dmu_free_long_range(objset_t *os, uint64_t object,
484     uint64_t offset, uint64_t length)
485 {
486 	dnode_t *dn;
487 	int err;
488 
489 	err = dnode_hold(os, object, FTAG, &dn);
490 	if (err != 0)
491 		return (err);
492 	err = dmu_free_long_range_impl(os, dn, offset, length, FALSE);
493 	dnode_rele(dn, FTAG);
494 	return (err);
495 }
496 
497 int
498 dmu_free_object(objset_t *os, uint64_t object)
499 {
500 	dnode_t *dn;
501 	dmu_tx_t *tx;
502 	int err;
503 
504 	err = dnode_hold_impl(os, object, DNODE_MUST_BE_ALLOCATED,
505 	    FTAG, &dn);
506 	if (err != 0)
507 		return (err);
508 	if (dn->dn_nlevels == 1) {
509 		tx = dmu_tx_create(os);
510 		dmu_tx_hold_bonus(tx, object);
511 		dmu_tx_hold_free(tx, dn->dn_object, 0, DMU_OBJECT_END);
512 		err = dmu_tx_assign(tx, TXG_WAIT);
513 		if (err == 0) {
514 			dnode_free_range(dn, 0, DMU_OBJECT_END, tx);
515 			dnode_free(dn, tx);
516 			dmu_tx_commit(tx);
517 		} else {
518 			dmu_tx_abort(tx);
519 		}
520 	} else {
521 		err = dmu_free_long_range_impl(os, dn, 0, DMU_OBJECT_END, TRUE);
522 	}
523 	dnode_rele(dn, FTAG);
524 	return (err);
525 }
526 
527 int
528 dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
529     uint64_t size, dmu_tx_t *tx)
530 {
531 	dnode_t *dn;
532 	int err = dnode_hold(os, object, FTAG, &dn);
533 	if (err)
534 		return (err);
535 	ASSERT(offset < UINT64_MAX);
536 	ASSERT(size == -1ULL || size <= UINT64_MAX - offset);
537 	dnode_free_range(dn, offset, size, tx);
538 	dnode_rele(dn, FTAG);
539 	return (0);
540 }
541 
542 int
543 dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
544     void *buf, uint32_t flags)
545 {
546 	dnode_t *dn;
547 	dmu_buf_t **dbp;
548 	int numbufs, err;
549 
550 	err = dnode_hold(os, object, FTAG, &dn);
551 	if (err)
552 		return (err);
553 
554 	/*
555 	 * Deal with odd block sizes, where there can't be data past the first
556 	 * block.  If we ever do the tail block optimization, we will need to
557 	 * handle that here as well.
558 	 */
559 	if (dn->dn_maxblkid == 0) {
560 		int newsz = offset > dn->dn_datablksz ? 0 :
561 		    MIN(size, dn->dn_datablksz - offset);
562 		bzero((char *)buf + newsz, size - newsz);
563 		size = newsz;
564 	}
565 
566 	while (size > 0) {
567 		uint64_t mylen = MIN(size, DMU_MAX_ACCESS / 2);
568 		int i;
569 
570 		/*
571 		 * NB: we could do this block-at-a-time, but it's nice
572 		 * to be reading in parallel.
573 		 */
574 		err = dmu_buf_hold_array_by_dnode(dn, offset, mylen,
575 		    TRUE, FTAG, &numbufs, &dbp, flags);
576 		if (err)
577 			break;
578 
579 		for (i = 0; i < numbufs; i++) {
580 			int tocpy;
581 			int bufoff;
582 			dmu_buf_t *db = dbp[i];
583 
584 			ASSERT(size > 0);
585 
586 			bufoff = offset - db->db_offset;
587 			tocpy = (int)MIN(db->db_size - bufoff, size);
588 
589 			bcopy((char *)db->db_data + bufoff, buf, tocpy);
590 
591 			offset += tocpy;
592 			size -= tocpy;
593 			buf = (char *)buf + tocpy;
594 		}
595 		dmu_buf_rele_array(dbp, numbufs, FTAG);
596 	}
597 	dnode_rele(dn, FTAG);
598 	return (err);
599 }
600 
601 void
602 dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
603     const void *buf, dmu_tx_t *tx)
604 {
605 	dmu_buf_t **dbp;
606 	int numbufs, i;
607 
608 	if (size == 0)
609 		return;
610 
611 	VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
612 	    FALSE, FTAG, &numbufs, &dbp));
613 
614 	for (i = 0; i < numbufs; i++) {
615 		int tocpy;
616 		int bufoff;
617 		dmu_buf_t *db = dbp[i];
618 
619 		ASSERT(size > 0);
620 
621 		bufoff = offset - db->db_offset;
622 		tocpy = (int)MIN(db->db_size - bufoff, size);
623 
624 		ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
625 
626 		if (tocpy == db->db_size)
627 			dmu_buf_will_fill(db, tx);
628 		else
629 			dmu_buf_will_dirty(db, tx);
630 
631 		bcopy(buf, (char *)db->db_data + bufoff, tocpy);
632 
633 		if (tocpy == db->db_size)
634 			dmu_buf_fill_done(db, tx);
635 
636 		offset += tocpy;
637 		size -= tocpy;
638 		buf = (char *)buf + tocpy;
639 	}
640 	dmu_buf_rele_array(dbp, numbufs, FTAG);
641 }
642 
643 void
644 dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
645     dmu_tx_t *tx)
646 {
647 	dmu_buf_t **dbp;
648 	int numbufs, i;
649 
650 	if (size == 0)
651 		return;
652 
653 	VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
654 	    FALSE, FTAG, &numbufs, &dbp));
655 
656 	for (i = 0; i < numbufs; i++) {
657 		dmu_buf_t *db = dbp[i];
658 
659 		dmu_buf_will_not_fill(db, tx);
660 	}
661 	dmu_buf_rele_array(dbp, numbufs, FTAG);
662 }
663 
664 #ifdef _KERNEL
665 int
666 dmu_read_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size)
667 {
668 	dmu_buf_t **dbp;
669 	int numbufs, i, err;
670 
671 	/*
672 	 * NB: we could do this block-at-a-time, but it's nice
673 	 * to be reading in parallel.
674 	 */
675 	err = dmu_buf_hold_array(os, object, uio->uio_loffset, size, TRUE, FTAG,
676 	    &numbufs, &dbp);
677 	if (err)
678 		return (err);
679 
680 	for (i = 0; i < numbufs; i++) {
681 		int tocpy;
682 		int bufoff;
683 		dmu_buf_t *db = dbp[i];
684 
685 		ASSERT(size > 0);
686 
687 		bufoff = uio->uio_loffset - db->db_offset;
688 		tocpy = (int)MIN(db->db_size - bufoff, size);
689 
690 		err = uiomove((char *)db->db_data + bufoff, tocpy,
691 		    UIO_READ, uio);
692 		if (err)
693 			break;
694 
695 		size -= tocpy;
696 	}
697 	dmu_buf_rele_array(dbp, numbufs, FTAG);
698 
699 	return (err);
700 }
701 
702 int
703 dmu_write_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size,
704     dmu_tx_t *tx)
705 {
706 	dmu_buf_t **dbp;
707 	int numbufs, i;
708 	int err = 0;
709 
710 	if (size == 0)
711 		return (0);
712 
713 	err = dmu_buf_hold_array(os, object, uio->uio_loffset, size,
714 	    FALSE, FTAG, &numbufs, &dbp);
715 	if (err)
716 		return (err);
717 
718 	for (i = 0; i < numbufs; i++) {
719 		int tocpy;
720 		int bufoff;
721 		dmu_buf_t *db = dbp[i];
722 
723 		ASSERT(size > 0);
724 
725 		bufoff = uio->uio_loffset - db->db_offset;
726 		tocpy = (int)MIN(db->db_size - bufoff, size);
727 
728 		ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
729 
730 		if (tocpy == db->db_size)
731 			dmu_buf_will_fill(db, tx);
732 		else
733 			dmu_buf_will_dirty(db, tx);
734 
735 		/*
736 		 * XXX uiomove could block forever (eg. nfs-backed
737 		 * pages).  There needs to be a uiolockdown() function
738 		 * to lock the pages in memory, so that uiomove won't
739 		 * block.
740 		 */
741 		err = uiomove((char *)db->db_data + bufoff, tocpy,
742 		    UIO_WRITE, uio);
743 
744 		if (tocpy == db->db_size)
745 			dmu_buf_fill_done(db, tx);
746 
747 		if (err)
748 			break;
749 
750 		size -= tocpy;
751 	}
752 	dmu_buf_rele_array(dbp, numbufs, FTAG);
753 	return (err);
754 }
755 
756 int
757 dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
758     page_t *pp, dmu_tx_t *tx)
759 {
760 	dmu_buf_t **dbp;
761 	int numbufs, i;
762 	int err;
763 
764 	if (size == 0)
765 		return (0);
766 
767 	err = dmu_buf_hold_array(os, object, offset, size,
768 	    FALSE, FTAG, &numbufs, &dbp);
769 	if (err)
770 		return (err);
771 
772 	for (i = 0; i < numbufs; i++) {
773 		int tocpy, copied, thiscpy;
774 		int bufoff;
775 		dmu_buf_t *db = dbp[i];
776 		caddr_t va;
777 
778 		ASSERT(size > 0);
779 		ASSERT3U(db->db_size, >=, PAGESIZE);
780 
781 		bufoff = offset - db->db_offset;
782 		tocpy = (int)MIN(db->db_size - bufoff, size);
783 
784 		ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
785 
786 		if (tocpy == db->db_size)
787 			dmu_buf_will_fill(db, tx);
788 		else
789 			dmu_buf_will_dirty(db, tx);
790 
791 		for (copied = 0; copied < tocpy; copied += PAGESIZE) {
792 			ASSERT3U(pp->p_offset, ==, db->db_offset + bufoff);
793 			thiscpy = MIN(PAGESIZE, tocpy - copied);
794 			va = zfs_map_page(pp, S_READ);
795 			bcopy(va, (char *)db->db_data + bufoff, thiscpy);
796 			zfs_unmap_page(pp, va);
797 			pp = pp->p_next;
798 			bufoff += PAGESIZE;
799 		}
800 
801 		if (tocpy == db->db_size)
802 			dmu_buf_fill_done(db, tx);
803 
804 		offset += tocpy;
805 		size -= tocpy;
806 	}
807 	dmu_buf_rele_array(dbp, numbufs, FTAG);
808 	return (err);
809 }
810 #endif
811 
812 /*
813  * Allocate a loaned anonymous arc buffer.
814  */
815 arc_buf_t *
816 dmu_request_arcbuf(dmu_buf_t *handle, int size)
817 {
818 	dnode_t *dn = ((dmu_buf_impl_t *)handle)->db_dnode;
819 
820 	return (arc_loan_buf(dn->dn_objset->os_spa, size));
821 }
822 
823 /*
824  * Free a loaned arc buffer.
825  */
826 void
827 dmu_return_arcbuf(arc_buf_t *buf)
828 {
829 	arc_return_buf(buf, FTAG);
830 	VERIFY(arc_buf_remove_ref(buf, FTAG) == 1);
831 }
832 
833 /*
834  * When possible directly assign passed loaned arc buffer to a dbuf.
835  * If this is not possible copy the contents of passed arc buf via
836  * dmu_write().
837  */
838 void
839 dmu_assign_arcbuf(dmu_buf_t *handle, uint64_t offset, arc_buf_t *buf,
840     dmu_tx_t *tx)
841 {
842 	dnode_t *dn = ((dmu_buf_impl_t *)handle)->db_dnode;
843 	dmu_buf_impl_t *db;
844 	uint32_t blksz = (uint32_t)arc_buf_size(buf);
845 	uint64_t blkid;
846 
847 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
848 	blkid = dbuf_whichblock(dn, offset);
849 	VERIFY((db = dbuf_hold(dn, blkid, FTAG)) != NULL);
850 	rw_exit(&dn->dn_struct_rwlock);
851 
852 	if (offset == db->db.db_offset && blksz == db->db.db_size) {
853 		dbuf_assign_arcbuf(db, buf, tx);
854 		dbuf_rele(db, FTAG);
855 	} else {
856 		dbuf_rele(db, FTAG);
857 		dmu_write(dn->dn_objset, dn->dn_object, offset, blksz,
858 		    buf->b_data, tx);
859 		dmu_return_arcbuf(buf);
860 	}
861 }
862 
863 typedef struct {
864 	dbuf_dirty_record_t	*dsa_dr;
865 	dmu_sync_cb_t		*dsa_done;
866 	zgd_t			*dsa_zgd;
867 	dmu_tx_t		*dsa_tx;
868 } dmu_sync_arg_t;
869 
870 /* ARGSUSED */
871 static void
872 dmu_sync_ready(zio_t *zio, arc_buf_t *buf, void *varg)
873 {
874 	dmu_sync_arg_t *dsa = varg;
875 	dmu_buf_t *db = dsa->dsa_zgd->zgd_db;
876 	dnode_t *dn = ((dmu_buf_impl_t *)db)->db_dnode;
877 	blkptr_t *bp = zio->io_bp;
878 
879 	if (zio->io_error == 0) {
880 		if (BP_IS_HOLE(bp)) {
881 			/*
882 			 * A block of zeros may compress to a hole, but the
883 			 * block size still needs to be known for replay.
884 			 */
885 			BP_SET_LSIZE(bp, db->db_size);
886 		} else {
887 			ASSERT(BP_GET_TYPE(bp) == dn->dn_type);
888 			ASSERT(BP_GET_LEVEL(bp) == 0);
889 			bp->blk_fill = 1;
890 		}
891 	}
892 }
893 
894 static void
895 dmu_sync_late_arrival_ready(zio_t *zio)
896 {
897 	dmu_sync_ready(zio, NULL, zio->io_private);
898 }
899 
900 /* ARGSUSED */
901 static void
902 dmu_sync_done(zio_t *zio, arc_buf_t *buf, void *varg)
903 {
904 	dmu_sync_arg_t *dsa = varg;
905 	dbuf_dirty_record_t *dr = dsa->dsa_dr;
906 	dmu_buf_impl_t *db = dr->dr_dbuf;
907 
908 	mutex_enter(&db->db_mtx);
909 	ASSERT(dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC);
910 	if (zio->io_error == 0) {
911 		dr->dt.dl.dr_overridden_by = *zio->io_bp;
912 		dr->dt.dl.dr_override_state = DR_OVERRIDDEN;
913 		dr->dt.dl.dr_copies = zio->io_prop.zp_copies;
914 		if (BP_IS_HOLE(&dr->dt.dl.dr_overridden_by))
915 			BP_ZERO(&dr->dt.dl.dr_overridden_by);
916 	} else {
917 		dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
918 	}
919 	cv_broadcast(&db->db_changed);
920 	mutex_exit(&db->db_mtx);
921 
922 	dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
923 
924 	kmem_free(dsa, sizeof (*dsa));
925 }
926 
927 static void
928 dmu_sync_late_arrival_done(zio_t *zio)
929 {
930 	blkptr_t *bp = zio->io_bp;
931 	dmu_sync_arg_t *dsa = zio->io_private;
932 
933 	if (zio->io_error == 0 && !BP_IS_HOLE(bp)) {
934 		ASSERT(zio->io_bp->blk_birth == zio->io_txg);
935 		ASSERT(zio->io_txg > spa_syncing_txg(zio->io_spa));
936 		zio_free(zio->io_spa, zio->io_txg, zio->io_bp);
937 	}
938 
939 	dmu_tx_commit(dsa->dsa_tx);
940 
941 	dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
942 
943 	kmem_free(dsa, sizeof (*dsa));
944 }
945 
946 static int
947 dmu_sync_late_arrival(zio_t *pio, objset_t *os, dmu_sync_cb_t *done, zgd_t *zgd,
948     zio_prop_t *zp, zbookmark_t *zb)
949 {
950 	dmu_sync_arg_t *dsa;
951 	dmu_tx_t *tx;
952 
953 	tx = dmu_tx_create(os);
954 	dmu_tx_hold_space(tx, zgd->zgd_db->db_size);
955 	if (dmu_tx_assign(tx, TXG_NOWAIT) != 0) {
956 		dmu_tx_abort(tx);
957 		return (EIO);	/* Make zl_get_data do txg_waited_synced() */
958 	}
959 
960 	dsa = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
961 	dsa->dsa_dr = NULL;
962 	dsa->dsa_done = done;
963 	dsa->dsa_zgd = zgd;
964 	dsa->dsa_tx = tx;
965 
966 	zio_nowait(zio_write(pio, os->os_spa, dmu_tx_get_txg(tx), zgd->zgd_bp,
967 	    zgd->zgd_db->db_data, zgd->zgd_db->db_size, zp,
968 	    dmu_sync_late_arrival_ready, dmu_sync_late_arrival_done, dsa,
969 	    ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_CANFAIL, zb));
970 
971 	return (0);
972 }
973 
974 /*
975  * Intent log support: sync the block associated with db to disk.
976  * N.B. and XXX: the caller is responsible for making sure that the
977  * data isn't changing while dmu_sync() is writing it.
978  *
979  * Return values:
980  *
981  *	EEXIST: this txg has already been synced, so there's nothing to to.
982  *		The caller should not log the write.
983  *
984  *	ENOENT: the block was dbuf_free_range()'d, so there's nothing to do.
985  *		The caller should not log the write.
986  *
987  *	EALREADY: this block is already in the process of being synced.
988  *		The caller should track its progress (somehow).
989  *
990  *	EIO: could not do the I/O.
991  *		The caller should do a txg_wait_synced().
992  *
993  *	0: the I/O has been initiated.
994  *		The caller should log this blkptr in the done callback.
995  *		It is possible that the I/O will fail, in which case
996  *		the error will be reported to the done callback and
997  *		propagated to pio from zio_done().
998  */
999 int
1000 dmu_sync(zio_t *pio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd)
1001 {
1002 	blkptr_t *bp = zgd->zgd_bp;
1003 	dmu_buf_impl_t *db = (dmu_buf_impl_t *)zgd->zgd_db;
1004 	objset_t *os = db->db_objset;
1005 	dsl_dataset_t *ds = os->os_dsl_dataset;
1006 	dbuf_dirty_record_t *dr;
1007 	dmu_sync_arg_t *dsa;
1008 	zbookmark_t zb;
1009 	zio_prop_t zp;
1010 
1011 	ASSERT(pio != NULL);
1012 	ASSERT(BP_IS_HOLE(bp));
1013 	ASSERT(txg != 0);
1014 
1015 	SET_BOOKMARK(&zb, ds->ds_object,
1016 	    db->db.db_object, db->db_level, db->db_blkid);
1017 
1018 	dmu_write_policy(os, db->db_dnode, db->db_level, WP_DMU_SYNC, &zp);
1019 
1020 	/*
1021 	 * If we're frozen (running ziltest), we always need to generate a bp.
1022 	 */
1023 	if (txg > spa_freeze_txg(os->os_spa))
1024 		return (dmu_sync_late_arrival(pio, os, done, zgd, &zp, &zb));
1025 
1026 	/*
1027 	 * Grabbing db_mtx now provides a barrier between dbuf_sync_leaf()
1028 	 * and us.  If we determine that this txg is not yet syncing,
1029 	 * but it begins to sync a moment later, that's OK because the
1030 	 * sync thread will block in dbuf_sync_leaf() until we drop db_mtx.
1031 	 */
1032 	mutex_enter(&db->db_mtx);
1033 
1034 	if (txg <= spa_last_synced_txg(os->os_spa)) {
1035 		/*
1036 		 * This txg has already synced.  There's nothing to do.
1037 		 */
1038 		mutex_exit(&db->db_mtx);
1039 		return (EEXIST);
1040 	}
1041 
1042 	if (txg <= spa_syncing_txg(os->os_spa)) {
1043 		/*
1044 		 * This txg is currently syncing, so we can't mess with
1045 		 * the dirty record anymore; just write a new log block.
1046 		 */
1047 		mutex_exit(&db->db_mtx);
1048 		return (dmu_sync_late_arrival(pio, os, done, zgd, &zp, &zb));
1049 	}
1050 
1051 	dr = db->db_last_dirty;
1052 	while (dr && dr->dr_txg != txg)
1053 		dr = dr->dr_next;
1054 
1055 	if (dr == NULL) {
1056 		/*
1057 		 * There's no dr for this dbuf, so it must have been freed.
1058 		 * There's no need to log writes to freed blocks, so we're done.
1059 		 */
1060 		mutex_exit(&db->db_mtx);
1061 		return (ENOENT);
1062 	}
1063 
1064 	ASSERT(dr->dr_txg == txg);
1065 	if (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC ||
1066 	    dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
1067 		/*
1068 		 * We have already issued a sync write for this buffer,
1069 		 * or this buffer has already been synced.  It could not
1070 		 * have been dirtied since, or we would have cleared the state.
1071 		 */
1072 		mutex_exit(&db->db_mtx);
1073 		return (EALREADY);
1074 	}
1075 
1076 	ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
1077 	dr->dt.dl.dr_override_state = DR_IN_DMU_SYNC;
1078 	mutex_exit(&db->db_mtx);
1079 
1080 	dsa = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
1081 	dsa->dsa_dr = dr;
1082 	dsa->dsa_done = done;
1083 	dsa->dsa_zgd = zgd;
1084 	dsa->dsa_tx = NULL;
1085 
1086 	zio_nowait(arc_write(pio, os->os_spa, txg,
1087 	    bp, dr->dt.dl.dr_data, DBUF_IS_L2CACHEABLE(db), &zp,
1088 	    dmu_sync_ready, dmu_sync_done, dsa,
1089 	    ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_CANFAIL, &zb));
1090 
1091 	return (0);
1092 }
1093 
1094 int
1095 dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size, int ibs,
1096 	dmu_tx_t *tx)
1097 {
1098 	dnode_t *dn;
1099 	int err;
1100 
1101 	err = dnode_hold(os, object, FTAG, &dn);
1102 	if (err)
1103 		return (err);
1104 	err = dnode_set_blksz(dn, size, ibs, tx);
1105 	dnode_rele(dn, FTAG);
1106 	return (err);
1107 }
1108 
1109 void
1110 dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
1111 	dmu_tx_t *tx)
1112 {
1113 	dnode_t *dn;
1114 
1115 	/* XXX assumes dnode_hold will not get an i/o error */
1116 	(void) dnode_hold(os, object, FTAG, &dn);
1117 	ASSERT(checksum < ZIO_CHECKSUM_FUNCTIONS);
1118 	dn->dn_checksum = checksum;
1119 	dnode_setdirty(dn, tx);
1120 	dnode_rele(dn, FTAG);
1121 }
1122 
1123 void
1124 dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
1125 	dmu_tx_t *tx)
1126 {
1127 	dnode_t *dn;
1128 
1129 	/* XXX assumes dnode_hold will not get an i/o error */
1130 	(void) dnode_hold(os, object, FTAG, &dn);
1131 	ASSERT(compress < ZIO_COMPRESS_FUNCTIONS);
1132 	dn->dn_compress = compress;
1133 	dnode_setdirty(dn, tx);
1134 	dnode_rele(dn, FTAG);
1135 }
1136 
1137 int zfs_mdcomp_disable = 0;
1138 
1139 void
1140 dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp, zio_prop_t *zp)
1141 {
1142 	dmu_object_type_t type = dn ? dn->dn_type : DMU_OT_OBJSET;
1143 	boolean_t ismd = (level > 0 || dmu_ot[type].ot_metadata);
1144 	enum zio_checksum checksum = os->os_checksum;
1145 	enum zio_compress compress = os->os_compress;
1146 	enum zio_checksum dedup_checksum = os->os_dedup_checksum;
1147 	boolean_t dedup;
1148 	boolean_t dedup_verify = os->os_dedup_verify;
1149 	int copies = os->os_copies;
1150 
1151 	/*
1152 	 * Determine checksum setting.
1153 	 */
1154 	if (ismd) {
1155 		/*
1156 		 * Metadata always gets checksummed.  If the data
1157 		 * checksum is multi-bit correctable, and it's not a
1158 		 * ZBT-style checksum, then it's suitable for metadata
1159 		 * as well.  Otherwise, the metadata checksum defaults
1160 		 * to fletcher4.
1161 		 */
1162 		if (zio_checksum_table[checksum].ci_correctable < 1 ||
1163 		    zio_checksum_table[checksum].ci_zbt)
1164 			checksum = ZIO_CHECKSUM_FLETCHER_4;
1165 	} else {
1166 		checksum = zio_checksum_select(dn->dn_checksum, checksum);
1167 	}
1168 
1169 	/*
1170 	 * Determine compression setting.
1171 	 */
1172 	if (ismd) {
1173 		/*
1174 		 * XXX -- we should design a compression algorithm
1175 		 * that specializes in arrays of bps.
1176 		 */
1177 		compress = zfs_mdcomp_disable ? ZIO_COMPRESS_EMPTY :
1178 		    ZIO_COMPRESS_LZJB;
1179 	} else {
1180 		compress = zio_compress_select(dn->dn_compress, compress);
1181 	}
1182 
1183 	/*
1184 	 * Determine dedup setting.  If we are in dmu_sync(), we won't
1185 	 * actually dedup now because that's all done in syncing context;
1186 	 * but we do want to use the dedup checkum.  If the checksum is not
1187 	 * strong enough to ensure unique signatures, force dedup_verify.
1188 	 */
1189 	dedup = (!ismd && dedup_checksum != ZIO_CHECKSUM_OFF);
1190 	if (dedup) {
1191 		checksum = dedup_checksum;
1192 		if (!zio_checksum_table[checksum].ci_dedup)
1193 			dedup_verify = 1;
1194 	}
1195 
1196 	if (wp & WP_DMU_SYNC)
1197 		dedup = 0;
1198 
1199 	if (wp & WP_NOFILL) {
1200 		ASSERT(!ismd && level == 0);
1201 		checksum = ZIO_CHECKSUM_OFF;
1202 		compress = ZIO_COMPRESS_OFF;
1203 		dedup = B_FALSE;
1204 	}
1205 
1206 	zp->zp_checksum = checksum;
1207 	zp->zp_compress = compress;
1208 	zp->zp_type = type;
1209 	zp->zp_level = level;
1210 	zp->zp_copies = MIN(copies + ismd, spa_max_replication(os->os_spa));
1211 	zp->zp_dedup = dedup;
1212 	zp->zp_dedup_verify = dedup && dedup_verify;
1213 }
1214 
1215 int
1216 dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole, uint64_t *off)
1217 {
1218 	dnode_t *dn;
1219 	int i, err;
1220 
1221 	err = dnode_hold(os, object, FTAG, &dn);
1222 	if (err)
1223 		return (err);
1224 	/*
1225 	 * Sync any current changes before
1226 	 * we go trundling through the block pointers.
1227 	 */
1228 	for (i = 0; i < TXG_SIZE; i++) {
1229 		if (list_link_active(&dn->dn_dirty_link[i]))
1230 			break;
1231 	}
1232 	if (i != TXG_SIZE) {
1233 		dnode_rele(dn, FTAG);
1234 		txg_wait_synced(dmu_objset_pool(os), 0);
1235 		err = dnode_hold(os, object, FTAG, &dn);
1236 		if (err)
1237 			return (err);
1238 	}
1239 
1240 	err = dnode_next_offset(dn, (hole ? DNODE_FIND_HOLE : 0), off, 1, 1, 0);
1241 	dnode_rele(dn, FTAG);
1242 
1243 	return (err);
1244 }
1245 
1246 void
1247 dmu_object_info_from_dnode(dnode_t *dn, dmu_object_info_t *doi)
1248 {
1249 	dnode_phys_t *dnp;
1250 
1251 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
1252 	mutex_enter(&dn->dn_mtx);
1253 
1254 	dnp = dn->dn_phys;
1255 
1256 	doi->doi_data_block_size = dn->dn_datablksz;
1257 	doi->doi_metadata_block_size = dn->dn_indblkshift ?
1258 	    1ULL << dn->dn_indblkshift : 0;
1259 	doi->doi_type = dn->dn_type;
1260 	doi->doi_bonus_type = dn->dn_bonustype;
1261 	doi->doi_bonus_size = dn->dn_bonuslen;
1262 	doi->doi_indirection = dn->dn_nlevels;
1263 	doi->doi_checksum = dn->dn_checksum;
1264 	doi->doi_compress = dn->dn_compress;
1265 	doi->doi_physical_blocks_512 = (DN_USED_BYTES(dnp) + 256) >> 9;
1266 	doi->doi_max_offset = (dnp->dn_maxblkid + 1) * dn->dn_datablksz;
1267 	doi->doi_fill_count = 0;
1268 	for (int i = 0; i < dnp->dn_nblkptr; i++)
1269 		doi->doi_fill_count += dnp->dn_blkptr[i].blk_fill;
1270 
1271 	mutex_exit(&dn->dn_mtx);
1272 	rw_exit(&dn->dn_struct_rwlock);
1273 }
1274 
1275 /*
1276  * Get information on a DMU object.
1277  * If doi is NULL, just indicates whether the object exists.
1278  */
1279 int
1280 dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi)
1281 {
1282 	dnode_t *dn;
1283 	int err = dnode_hold(os, object, FTAG, &dn);
1284 
1285 	if (err)
1286 		return (err);
1287 
1288 	if (doi != NULL)
1289 		dmu_object_info_from_dnode(dn, doi);
1290 
1291 	dnode_rele(dn, FTAG);
1292 	return (0);
1293 }
1294 
1295 /*
1296  * As above, but faster; can be used when you have a held dbuf in hand.
1297  */
1298 void
1299 dmu_object_info_from_db(dmu_buf_t *db, dmu_object_info_t *doi)
1300 {
1301 	dmu_object_info_from_dnode(((dmu_buf_impl_t *)db)->db_dnode, doi);
1302 }
1303 
1304 /*
1305  * Faster still when you only care about the size.
1306  * This is specifically optimized for zfs_getattr().
1307  */
1308 void
1309 dmu_object_size_from_db(dmu_buf_t *db, uint32_t *blksize, u_longlong_t *nblk512)
1310 {
1311 	dnode_t *dn = ((dmu_buf_impl_t *)db)->db_dnode;
1312 
1313 	*blksize = dn->dn_datablksz;
1314 	/* add 1 for dnode space */
1315 	*nblk512 = ((DN_USED_BYTES(dn->dn_phys) + SPA_MINBLOCKSIZE/2) >>
1316 	    SPA_MINBLOCKSHIFT) + 1;
1317 }
1318 
1319 void
1320 byteswap_uint64_array(void *vbuf, size_t size)
1321 {
1322 	uint64_t *buf = vbuf;
1323 	size_t count = size >> 3;
1324 	int i;
1325 
1326 	ASSERT((size & 7) == 0);
1327 
1328 	for (i = 0; i < count; i++)
1329 		buf[i] = BSWAP_64(buf[i]);
1330 }
1331 
1332 void
1333 byteswap_uint32_array(void *vbuf, size_t size)
1334 {
1335 	uint32_t *buf = vbuf;
1336 	size_t count = size >> 2;
1337 	int i;
1338 
1339 	ASSERT((size & 3) == 0);
1340 
1341 	for (i = 0; i < count; i++)
1342 		buf[i] = BSWAP_32(buf[i]);
1343 }
1344 
1345 void
1346 byteswap_uint16_array(void *vbuf, size_t size)
1347 {
1348 	uint16_t *buf = vbuf;
1349 	size_t count = size >> 1;
1350 	int i;
1351 
1352 	ASSERT((size & 1) == 0);
1353 
1354 	for (i = 0; i < count; i++)
1355 		buf[i] = BSWAP_16(buf[i]);
1356 }
1357 
1358 /* ARGSUSED */
1359 void
1360 byteswap_uint8_array(void *vbuf, size_t size)
1361 {
1362 }
1363 
1364 void
1365 dmu_init(void)
1366 {
1367 	dbuf_init();
1368 	dnode_init();
1369 	zfetch_init();
1370 	arc_init();
1371 	l2arc_init();
1372 }
1373 
1374 void
1375 dmu_fini(void)
1376 {
1377 	arc_fini();
1378 	zfetch_fini();
1379 	dnode_fini();
1380 	dbuf_fini();
1381 	l2arc_fini();
1382 }
1383