dmu.c revision 273350
1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright (c) 2011, 2014 by Delphix. All rights reserved.
24 */
25/* Copyright (c) 2013 by Saso Kiselkov. All rights reserved. */
26/* Copyright (c) 2013, Joyent, Inc. All rights reserved. */
27/* Copyright (c) 2014, Nexenta Systems, Inc. All rights reserved. */
28
29#include <sys/dmu.h>
30#include <sys/dmu_impl.h>
31#include <sys/dmu_tx.h>
32#include <sys/dbuf.h>
33#include <sys/dnode.h>
34#include <sys/zfs_context.h>
35#include <sys/dmu_objset.h>
36#include <sys/dmu_traverse.h>
37#include <sys/dsl_dataset.h>
38#include <sys/dsl_dir.h>
39#include <sys/dsl_pool.h>
40#include <sys/dsl_synctask.h>
41#include <sys/dsl_prop.h>
42#include <sys/dmu_zfetch.h>
43#include <sys/zfs_ioctl.h>
44#include <sys/zap.h>
45#include <sys/zio_checksum.h>
46#include <sys/zio_compress.h>
47#include <sys/sa.h>
48#include <sys/zfeature.h>
49#ifdef _KERNEL
50#include <sys/vm.h>
51#include <sys/zfs_znode.h>
52#endif
53
54/*
55 * Enable/disable nopwrite feature.
56 */
57int zfs_nopwrite_enabled = 1;
58SYSCTL_DECL(_vfs_zfs);
59TUNABLE_INT("vfs.zfs.nopwrite_enabled", &zfs_nopwrite_enabled);
60SYSCTL_INT(_vfs_zfs, OID_AUTO, nopwrite_enabled, CTLFLAG_RDTUN,
61    &zfs_nopwrite_enabled, 0, "Enable nopwrite feature");
62
63const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES] = {
64	{	DMU_BSWAP_UINT8,	TRUE,	"unallocated"		},
65	{	DMU_BSWAP_ZAP,		TRUE,	"object directory"	},
66	{	DMU_BSWAP_UINT64,	TRUE,	"object array"		},
67	{	DMU_BSWAP_UINT8,	TRUE,	"packed nvlist"		},
68	{	DMU_BSWAP_UINT64,	TRUE,	"packed nvlist size"	},
69	{	DMU_BSWAP_UINT64,	TRUE,	"bpobj"			},
70	{	DMU_BSWAP_UINT64,	TRUE,	"bpobj header"		},
71	{	DMU_BSWAP_UINT64,	TRUE,	"SPA space map header"	},
72	{	DMU_BSWAP_UINT64,	TRUE,	"SPA space map"		},
73	{	DMU_BSWAP_UINT64,	TRUE,	"ZIL intent log"	},
74	{	DMU_BSWAP_DNODE,	TRUE,	"DMU dnode"		},
75	{	DMU_BSWAP_OBJSET,	TRUE,	"DMU objset"		},
76	{	DMU_BSWAP_UINT64,	TRUE,	"DSL directory"		},
77	{	DMU_BSWAP_ZAP,		TRUE,	"DSL directory child map"},
78	{	DMU_BSWAP_ZAP,		TRUE,	"DSL dataset snap map"	},
79	{	DMU_BSWAP_ZAP,		TRUE,	"DSL props"		},
80	{	DMU_BSWAP_UINT64,	TRUE,	"DSL dataset"		},
81	{	DMU_BSWAP_ZNODE,	TRUE,	"ZFS znode"		},
82	{	DMU_BSWAP_OLDACL,	TRUE,	"ZFS V0 ACL"		},
83	{	DMU_BSWAP_UINT8,	FALSE,	"ZFS plain file"	},
84	{	DMU_BSWAP_ZAP,		TRUE,	"ZFS directory"		},
85	{	DMU_BSWAP_ZAP,		TRUE,	"ZFS master node"	},
86	{	DMU_BSWAP_ZAP,		TRUE,	"ZFS delete queue"	},
87	{	DMU_BSWAP_UINT8,	FALSE,	"zvol object"		},
88	{	DMU_BSWAP_ZAP,		TRUE,	"zvol prop"		},
89	{	DMU_BSWAP_UINT8,	FALSE,	"other uint8[]"		},
90	{	DMU_BSWAP_UINT64,	FALSE,	"other uint64[]"	},
91	{	DMU_BSWAP_ZAP,		TRUE,	"other ZAP"		},
92	{	DMU_BSWAP_ZAP,		TRUE,	"persistent error log"	},
93	{	DMU_BSWAP_UINT8,	TRUE,	"SPA history"		},
94	{	DMU_BSWAP_UINT64,	TRUE,	"SPA history offsets"	},
95	{	DMU_BSWAP_ZAP,		TRUE,	"Pool properties"	},
96	{	DMU_BSWAP_ZAP,		TRUE,	"DSL permissions"	},
97	{	DMU_BSWAP_ACL,		TRUE,	"ZFS ACL"		},
98	{	DMU_BSWAP_UINT8,	TRUE,	"ZFS SYSACL"		},
99	{	DMU_BSWAP_UINT8,	TRUE,	"FUID table"		},
100	{	DMU_BSWAP_UINT64,	TRUE,	"FUID table size"	},
101	{	DMU_BSWAP_ZAP,		TRUE,	"DSL dataset next clones"},
102	{	DMU_BSWAP_ZAP,		TRUE,	"scan work queue"	},
103	{	DMU_BSWAP_ZAP,		TRUE,	"ZFS user/group used"	},
104	{	DMU_BSWAP_ZAP,		TRUE,	"ZFS user/group quota"	},
105	{	DMU_BSWAP_ZAP,		TRUE,	"snapshot refcount tags"},
106	{	DMU_BSWAP_ZAP,		TRUE,	"DDT ZAP algorithm"	},
107	{	DMU_BSWAP_ZAP,		TRUE,	"DDT statistics"	},
108	{	DMU_BSWAP_UINT8,	TRUE,	"System attributes"	},
109	{	DMU_BSWAP_ZAP,		TRUE,	"SA master node"	},
110	{	DMU_BSWAP_ZAP,		TRUE,	"SA attr registration"	},
111	{	DMU_BSWAP_ZAP,		TRUE,	"SA attr layouts"	},
112	{	DMU_BSWAP_ZAP,		TRUE,	"scan translations"	},
113	{	DMU_BSWAP_UINT8,	FALSE,	"deduplicated block"	},
114	{	DMU_BSWAP_ZAP,		TRUE,	"DSL deadlist map"	},
115	{	DMU_BSWAP_UINT64,	TRUE,	"DSL deadlist map hdr"	},
116	{	DMU_BSWAP_ZAP,		TRUE,	"DSL dir clones"	},
117	{	DMU_BSWAP_UINT64,	TRUE,	"bpobj subobj"		}
118};
119
120const dmu_object_byteswap_info_t dmu_ot_byteswap[DMU_BSWAP_NUMFUNCS] = {
121	{	byteswap_uint8_array,	"uint8"		},
122	{	byteswap_uint16_array,	"uint16"	},
123	{	byteswap_uint32_array,	"uint32"	},
124	{	byteswap_uint64_array,	"uint64"	},
125	{	zap_byteswap,		"zap"		},
126	{	dnode_buf_byteswap,	"dnode"		},
127	{	dmu_objset_byteswap,	"objset"	},
128	{	zfs_znode_byteswap,	"znode"		},
129	{	zfs_oldacl_byteswap,	"oldacl"	},
130	{	zfs_acl_byteswap,	"acl"		}
131};
132
133int
134dmu_buf_hold_noread(objset_t *os, uint64_t object, uint64_t offset,
135    void *tag, dmu_buf_t **dbp)
136{
137	dnode_t *dn;
138	uint64_t blkid;
139	dmu_buf_impl_t *db;
140	int err;
141
142	err = dnode_hold(os, object, FTAG, &dn);
143	if (err)
144		return (err);
145	blkid = dbuf_whichblock(dn, offset);
146	rw_enter(&dn->dn_struct_rwlock, RW_READER);
147	db = dbuf_hold(dn, blkid, tag);
148	rw_exit(&dn->dn_struct_rwlock);
149	dnode_rele(dn, FTAG);
150
151	if (db == NULL) {
152		*dbp = NULL;
153		return (SET_ERROR(EIO));
154	}
155
156	*dbp = &db->db;
157	return (err);
158}
159
160int
161dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
162    void *tag, dmu_buf_t **dbp, int flags)
163{
164	int err;
165	int db_flags = DB_RF_CANFAIL;
166
167	if (flags & DMU_READ_NO_PREFETCH)
168		db_flags |= DB_RF_NOPREFETCH;
169
170	err = dmu_buf_hold_noread(os, object, offset, tag, dbp);
171	if (err == 0) {
172		dmu_buf_impl_t *db = (dmu_buf_impl_t *)(*dbp);
173		err = dbuf_read(db, NULL, db_flags);
174		if (err != 0) {
175			dbuf_rele(db, tag);
176			*dbp = NULL;
177		}
178	}
179
180	return (err);
181}
182
183int
184dmu_bonus_max(void)
185{
186	return (DN_MAX_BONUSLEN);
187}
188
189int
190dmu_set_bonus(dmu_buf_t *db_fake, int newsize, dmu_tx_t *tx)
191{
192	dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
193	dnode_t *dn;
194	int error;
195
196	DB_DNODE_ENTER(db);
197	dn = DB_DNODE(db);
198
199	if (dn->dn_bonus != db) {
200		error = SET_ERROR(EINVAL);
201	} else if (newsize < 0 || newsize > db_fake->db_size) {
202		error = SET_ERROR(EINVAL);
203	} else {
204		dnode_setbonuslen(dn, newsize, tx);
205		error = 0;
206	}
207
208	DB_DNODE_EXIT(db);
209	return (error);
210}
211
212int
213dmu_set_bonustype(dmu_buf_t *db_fake, dmu_object_type_t type, dmu_tx_t *tx)
214{
215	dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
216	dnode_t *dn;
217	int error;
218
219	DB_DNODE_ENTER(db);
220	dn = DB_DNODE(db);
221
222	if (!DMU_OT_IS_VALID(type)) {
223		error = SET_ERROR(EINVAL);
224	} else if (dn->dn_bonus != db) {
225		error = SET_ERROR(EINVAL);
226	} else {
227		dnode_setbonus_type(dn, type, tx);
228		error = 0;
229	}
230
231	DB_DNODE_EXIT(db);
232	return (error);
233}
234
235dmu_object_type_t
236dmu_get_bonustype(dmu_buf_t *db_fake)
237{
238	dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
239	dnode_t *dn;
240	dmu_object_type_t type;
241
242	DB_DNODE_ENTER(db);
243	dn = DB_DNODE(db);
244	type = dn->dn_bonustype;
245	DB_DNODE_EXIT(db);
246
247	return (type);
248}
249
250int
251dmu_rm_spill(objset_t *os, uint64_t object, dmu_tx_t *tx)
252{
253	dnode_t *dn;
254	int error;
255
256	error = dnode_hold(os, object, FTAG, &dn);
257	dbuf_rm_spill(dn, tx);
258	rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
259	dnode_rm_spill(dn, tx);
260	rw_exit(&dn->dn_struct_rwlock);
261	dnode_rele(dn, FTAG);
262	return (error);
263}
264
265/*
266 * returns ENOENT, EIO, or 0.
267 */
268int
269dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **dbp)
270{
271	dnode_t *dn;
272	dmu_buf_impl_t *db;
273	int error;
274
275	error = dnode_hold(os, object, FTAG, &dn);
276	if (error)
277		return (error);
278
279	rw_enter(&dn->dn_struct_rwlock, RW_READER);
280	if (dn->dn_bonus == NULL) {
281		rw_exit(&dn->dn_struct_rwlock);
282		rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
283		if (dn->dn_bonus == NULL)
284			dbuf_create_bonus(dn);
285	}
286	db = dn->dn_bonus;
287
288	/* as long as the bonus buf is held, the dnode will be held */
289	if (refcount_add(&db->db_holds, tag) == 1) {
290		VERIFY(dnode_add_ref(dn, db));
291		atomic_inc_32(&dn->dn_dbufs_count);
292	}
293
294	/*
295	 * Wait to drop dn_struct_rwlock until after adding the bonus dbuf's
296	 * hold and incrementing the dbuf count to ensure that dnode_move() sees
297	 * a dnode hold for every dbuf.
298	 */
299	rw_exit(&dn->dn_struct_rwlock);
300
301	dnode_rele(dn, FTAG);
302
303	VERIFY(0 == dbuf_read(db, NULL, DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH));
304
305	*dbp = &db->db;
306	return (0);
307}
308
309/*
310 * returns ENOENT, EIO, or 0.
311 *
312 * This interface will allocate a blank spill dbuf when a spill blk
313 * doesn't already exist on the dnode.
314 *
315 * if you only want to find an already existing spill db, then
316 * dmu_spill_hold_existing() should be used.
317 */
318int
319dmu_spill_hold_by_dnode(dnode_t *dn, uint32_t flags, void *tag, dmu_buf_t **dbp)
320{
321	dmu_buf_impl_t *db = NULL;
322	int err;
323
324	if ((flags & DB_RF_HAVESTRUCT) == 0)
325		rw_enter(&dn->dn_struct_rwlock, RW_READER);
326
327	db = dbuf_hold(dn, DMU_SPILL_BLKID, tag);
328
329	if ((flags & DB_RF_HAVESTRUCT) == 0)
330		rw_exit(&dn->dn_struct_rwlock);
331
332	ASSERT(db != NULL);
333	err = dbuf_read(db, NULL, flags);
334	if (err == 0)
335		*dbp = &db->db;
336	else
337		dbuf_rele(db, tag);
338	return (err);
339}
340
341int
342dmu_spill_hold_existing(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp)
343{
344	dmu_buf_impl_t *db = (dmu_buf_impl_t *)bonus;
345	dnode_t *dn;
346	int err;
347
348	DB_DNODE_ENTER(db);
349	dn = DB_DNODE(db);
350
351	if (spa_version(dn->dn_objset->os_spa) < SPA_VERSION_SA) {
352		err = SET_ERROR(EINVAL);
353	} else {
354		rw_enter(&dn->dn_struct_rwlock, RW_READER);
355
356		if (!dn->dn_have_spill) {
357			err = SET_ERROR(ENOENT);
358		} else {
359			err = dmu_spill_hold_by_dnode(dn,
360			    DB_RF_HAVESTRUCT | DB_RF_CANFAIL, tag, dbp);
361		}
362
363		rw_exit(&dn->dn_struct_rwlock);
364	}
365
366	DB_DNODE_EXIT(db);
367	return (err);
368}
369
370int
371dmu_spill_hold_by_bonus(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp)
372{
373	dmu_buf_impl_t *db = (dmu_buf_impl_t *)bonus;
374	dnode_t *dn;
375	int err;
376
377	DB_DNODE_ENTER(db);
378	dn = DB_DNODE(db);
379	err = dmu_spill_hold_by_dnode(dn, DB_RF_CANFAIL, tag, dbp);
380	DB_DNODE_EXIT(db);
381
382	return (err);
383}
384
385/*
386 * Note: longer-term, we should modify all of the dmu_buf_*() interfaces
387 * to take a held dnode rather than <os, object> -- the lookup is wasteful,
388 * and can induce severe lock contention when writing to several files
389 * whose dnodes are in the same block.
390 */
391static int
392dmu_buf_hold_array_by_dnode(dnode_t *dn, uint64_t offset, uint64_t length,
393    int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp, uint32_t flags)
394{
395	dmu_buf_t **dbp;
396	uint64_t blkid, nblks, i;
397	uint32_t dbuf_flags;
398	int err;
399	zio_t *zio;
400
401	ASSERT(length <= DMU_MAX_ACCESS);
402
403	dbuf_flags = DB_RF_CANFAIL | DB_RF_NEVERWAIT | DB_RF_HAVESTRUCT;
404	if (flags & DMU_READ_NO_PREFETCH || length > zfetch_array_rd_sz)
405		dbuf_flags |= DB_RF_NOPREFETCH;
406
407	rw_enter(&dn->dn_struct_rwlock, RW_READER);
408	if (dn->dn_datablkshift) {
409		int blkshift = dn->dn_datablkshift;
410		nblks = (P2ROUNDUP(offset+length, 1ULL<<blkshift) -
411		    P2ALIGN(offset, 1ULL<<blkshift)) >> blkshift;
412	} else {
413		if (offset + length > dn->dn_datablksz) {
414			zfs_panic_recover("zfs: accessing past end of object "
415			    "%llx/%llx (size=%u access=%llu+%llu)",
416			    (longlong_t)dn->dn_objset->
417			    os_dsl_dataset->ds_object,
418			    (longlong_t)dn->dn_object, dn->dn_datablksz,
419			    (longlong_t)offset, (longlong_t)length);
420			rw_exit(&dn->dn_struct_rwlock);
421			return (SET_ERROR(EIO));
422		}
423		nblks = 1;
424	}
425	dbp = kmem_zalloc(sizeof (dmu_buf_t *) * nblks, KM_SLEEP);
426
427	zio = zio_root(dn->dn_objset->os_spa, NULL, NULL, ZIO_FLAG_CANFAIL);
428	blkid = dbuf_whichblock(dn, offset);
429	for (i = 0; i < nblks; i++) {
430		dmu_buf_impl_t *db = dbuf_hold(dn, blkid+i, tag);
431		if (db == NULL) {
432			rw_exit(&dn->dn_struct_rwlock);
433			dmu_buf_rele_array(dbp, nblks, tag);
434			zio_nowait(zio);
435			return (SET_ERROR(EIO));
436		}
437		/* initiate async i/o */
438		if (read)
439			(void) dbuf_read(db, zio, dbuf_flags);
440#ifdef _KERNEL
441		else
442			curthread->td_ru.ru_oublock++;
443#endif
444		dbp[i] = &db->db;
445	}
446	rw_exit(&dn->dn_struct_rwlock);
447
448	/* wait for async i/o */
449	err = zio_wait(zio);
450	if (err) {
451		dmu_buf_rele_array(dbp, nblks, tag);
452		return (err);
453	}
454
455	/* wait for other io to complete */
456	if (read) {
457		for (i = 0; i < nblks; i++) {
458			dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbp[i];
459			mutex_enter(&db->db_mtx);
460			while (db->db_state == DB_READ ||
461			    db->db_state == DB_FILL)
462				cv_wait(&db->db_changed, &db->db_mtx);
463			if (db->db_state == DB_UNCACHED)
464				err = SET_ERROR(EIO);
465			mutex_exit(&db->db_mtx);
466			if (err) {
467				dmu_buf_rele_array(dbp, nblks, tag);
468				return (err);
469			}
470		}
471	}
472
473	*numbufsp = nblks;
474	*dbpp = dbp;
475	return (0);
476}
477
478static int
479dmu_buf_hold_array(objset_t *os, uint64_t object, uint64_t offset,
480    uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
481{
482	dnode_t *dn;
483	int err;
484
485	err = dnode_hold(os, object, FTAG, &dn);
486	if (err)
487		return (err);
488
489	err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
490	    numbufsp, dbpp, DMU_READ_PREFETCH);
491
492	dnode_rele(dn, FTAG);
493
494	return (err);
495}
496
497int
498dmu_buf_hold_array_by_bonus(dmu_buf_t *db_fake, uint64_t offset,
499    uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
500{
501	dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
502	dnode_t *dn;
503	int err;
504
505	DB_DNODE_ENTER(db);
506	dn = DB_DNODE(db);
507	err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
508	    numbufsp, dbpp, DMU_READ_PREFETCH);
509	DB_DNODE_EXIT(db);
510
511	return (err);
512}
513
514void
515dmu_buf_rele_array(dmu_buf_t **dbp_fake, int numbufs, void *tag)
516{
517	int i;
518	dmu_buf_impl_t **dbp = (dmu_buf_impl_t **)dbp_fake;
519
520	if (numbufs == 0)
521		return;
522
523	for (i = 0; i < numbufs; i++) {
524		if (dbp[i])
525			dbuf_rele(dbp[i], tag);
526	}
527
528	kmem_free(dbp, sizeof (dmu_buf_t *) * numbufs);
529}
530
531/*
532 * Issue prefetch i/os for the given blocks.
533 *
534 * Note: The assumption is that we *know* these blocks will be needed
535 * almost immediately.  Therefore, the prefetch i/os will be issued at
536 * ZIO_PRIORITY_SYNC_READ
537 *
538 * Note: indirect blocks and other metadata will be read synchronously,
539 * causing this function to block if they are not already cached.
540 */
541void
542dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset, uint64_t len)
543{
544	dnode_t *dn;
545	uint64_t blkid;
546	int nblks, err;
547
548	if (zfs_prefetch_disable)
549		return;
550
551	if (len == 0) {  /* they're interested in the bonus buffer */
552		dn = DMU_META_DNODE(os);
553
554		if (object == 0 || object >= DN_MAX_OBJECT)
555			return;
556
557		rw_enter(&dn->dn_struct_rwlock, RW_READER);
558		blkid = dbuf_whichblock(dn, object * sizeof (dnode_phys_t));
559		dbuf_prefetch(dn, blkid, ZIO_PRIORITY_SYNC_READ);
560		rw_exit(&dn->dn_struct_rwlock);
561		return;
562	}
563
564	/*
565	 * XXX - Note, if the dnode for the requested object is not
566	 * already cached, we will do a *synchronous* read in the
567	 * dnode_hold() call.  The same is true for any indirects.
568	 */
569	err = dnode_hold(os, object, FTAG, &dn);
570	if (err != 0)
571		return;
572
573	rw_enter(&dn->dn_struct_rwlock, RW_READER);
574	if (dn->dn_datablkshift) {
575		int blkshift = dn->dn_datablkshift;
576		nblks = (P2ROUNDUP(offset + len, 1 << blkshift) -
577		    P2ALIGN(offset, 1 << blkshift)) >> blkshift;
578	} else {
579		nblks = (offset < dn->dn_datablksz);
580	}
581
582	if (nblks != 0) {
583		blkid = dbuf_whichblock(dn, offset);
584		for (int i = 0; i < nblks; i++)
585			dbuf_prefetch(dn, blkid + i, ZIO_PRIORITY_SYNC_READ);
586	}
587
588	rw_exit(&dn->dn_struct_rwlock);
589
590	dnode_rele(dn, FTAG);
591}
592
593/*
594 * Get the next "chunk" of file data to free.  We traverse the file from
595 * the end so that the file gets shorter over time (if we crashes in the
596 * middle, this will leave us in a better state).  We find allocated file
597 * data by simply searching the allocated level 1 indirects.
598 *
599 * On input, *start should be the first offset that does not need to be
600 * freed (e.g. "offset + length").  On return, *start will be the first
601 * offset that should be freed.
602 */
603static int
604get_next_chunk(dnode_t *dn, uint64_t *start, uint64_t minimum)
605{
606	uint64_t maxblks = DMU_MAX_ACCESS >> (dn->dn_indblkshift + 1);
607	/* bytes of data covered by a level-1 indirect block */
608	uint64_t iblkrange =
609	    dn->dn_datablksz * EPB(dn->dn_indblkshift, SPA_BLKPTRSHIFT);
610
611	ASSERT3U(minimum, <=, *start);
612
613	if (*start - minimum <= iblkrange * maxblks) {
614		*start = minimum;
615		return (0);
616	}
617	ASSERT(ISP2(iblkrange));
618
619	for (uint64_t blks = 0; *start > minimum && blks < maxblks; blks++) {
620		int err;
621
622		/*
623		 * dnode_next_offset(BACKWARDS) will find an allocated L1
624		 * indirect block at or before the input offset.  We must
625		 * decrement *start so that it is at the end of the region
626		 * to search.
627		 */
628		(*start)--;
629		err = dnode_next_offset(dn,
630		    DNODE_FIND_BACKWARDS, start, 2, 1, 0);
631
632		/* if there are no indirect blocks before start, we are done */
633		if (err == ESRCH) {
634			*start = minimum;
635			break;
636		} else if (err != 0) {
637			return (err);
638		}
639
640		/* set start to the beginning of this L1 indirect */
641		*start = P2ALIGN(*start, iblkrange);
642	}
643	if (*start < minimum)
644		*start = minimum;
645	return (0);
646}
647
648static int
649dmu_free_long_range_impl(objset_t *os, dnode_t *dn, uint64_t offset,
650    uint64_t length)
651{
652	uint64_t object_size = (dn->dn_maxblkid + 1) * dn->dn_datablksz;
653	int err;
654
655	if (offset >= object_size)
656		return (0);
657
658	if (length == DMU_OBJECT_END || offset + length > object_size)
659		length = object_size - offset;
660
661	while (length != 0) {
662		uint64_t chunk_end, chunk_begin;
663
664		chunk_end = chunk_begin = offset + length;
665
666		/* move chunk_begin backwards to the beginning of this chunk */
667		err = get_next_chunk(dn, &chunk_begin, offset);
668		if (err)
669			return (err);
670		ASSERT3U(chunk_begin, >=, offset);
671		ASSERT3U(chunk_begin, <=, chunk_end);
672
673		dmu_tx_t *tx = dmu_tx_create(os);
674		dmu_tx_hold_free(tx, dn->dn_object,
675		    chunk_begin, chunk_end - chunk_begin);
676
677		/*
678		 * Mark this transaction as typically resulting in a net
679		 * reduction in space used.
680		 */
681		dmu_tx_mark_netfree(tx);
682		err = dmu_tx_assign(tx, TXG_WAIT);
683		if (err) {
684			dmu_tx_abort(tx);
685			return (err);
686		}
687		dnode_free_range(dn, chunk_begin, chunk_end - chunk_begin, tx);
688		dmu_tx_commit(tx);
689
690		length -= chunk_end - chunk_begin;
691	}
692	return (0);
693}
694
695int
696dmu_free_long_range(objset_t *os, uint64_t object,
697    uint64_t offset, uint64_t length)
698{
699	dnode_t *dn;
700	int err;
701
702	err = dnode_hold(os, object, FTAG, &dn);
703	if (err != 0)
704		return (err);
705	err = dmu_free_long_range_impl(os, dn, offset, length);
706
707	/*
708	 * It is important to zero out the maxblkid when freeing the entire
709	 * file, so that (a) subsequent calls to dmu_free_long_range_impl()
710	 * will take the fast path, and (b) dnode_reallocate() can verify
711	 * that the entire file has been freed.
712	 */
713	if (err == 0 && offset == 0 && length == DMU_OBJECT_END)
714		dn->dn_maxblkid = 0;
715
716	dnode_rele(dn, FTAG);
717	return (err);
718}
719
720int
721dmu_free_long_object(objset_t *os, uint64_t object)
722{
723	dmu_tx_t *tx;
724	int err;
725
726	err = dmu_free_long_range(os, object, 0, DMU_OBJECT_END);
727	if (err != 0)
728		return (err);
729
730	tx = dmu_tx_create(os);
731	dmu_tx_hold_bonus(tx, object);
732	dmu_tx_hold_free(tx, object, 0, DMU_OBJECT_END);
733	dmu_tx_mark_netfree(tx);
734	err = dmu_tx_assign(tx, TXG_WAIT);
735	if (err == 0) {
736		err = dmu_object_free(os, object, tx);
737		dmu_tx_commit(tx);
738	} else {
739		dmu_tx_abort(tx);
740	}
741
742	return (err);
743}
744
745int
746dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
747    uint64_t size, dmu_tx_t *tx)
748{
749	dnode_t *dn;
750	int err = dnode_hold(os, object, FTAG, &dn);
751	if (err)
752		return (err);
753	ASSERT(offset < UINT64_MAX);
754	ASSERT(size == -1ULL || size <= UINT64_MAX - offset);
755	dnode_free_range(dn, offset, size, tx);
756	dnode_rele(dn, FTAG);
757	return (0);
758}
759
760int
761dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
762    void *buf, uint32_t flags)
763{
764	dnode_t *dn;
765	dmu_buf_t **dbp;
766	int numbufs, err;
767
768	err = dnode_hold(os, object, FTAG, &dn);
769	if (err)
770		return (err);
771
772	/*
773	 * Deal with odd block sizes, where there can't be data past the first
774	 * block.  If we ever do the tail block optimization, we will need to
775	 * handle that here as well.
776	 */
777	if (dn->dn_maxblkid == 0) {
778		int newsz = offset > dn->dn_datablksz ? 0 :
779		    MIN(size, dn->dn_datablksz - offset);
780		bzero((char *)buf + newsz, size - newsz);
781		size = newsz;
782	}
783
784	while (size > 0) {
785		uint64_t mylen = MIN(size, DMU_MAX_ACCESS / 2);
786		int i;
787
788		/*
789		 * NB: we could do this block-at-a-time, but it's nice
790		 * to be reading in parallel.
791		 */
792		err = dmu_buf_hold_array_by_dnode(dn, offset, mylen,
793		    TRUE, FTAG, &numbufs, &dbp, flags);
794		if (err)
795			break;
796
797		for (i = 0; i < numbufs; i++) {
798			int tocpy;
799			int bufoff;
800			dmu_buf_t *db = dbp[i];
801
802			ASSERT(size > 0);
803
804			bufoff = offset - db->db_offset;
805			tocpy = (int)MIN(db->db_size - bufoff, size);
806
807			bcopy((char *)db->db_data + bufoff, buf, tocpy);
808
809			offset += tocpy;
810			size -= tocpy;
811			buf = (char *)buf + tocpy;
812		}
813		dmu_buf_rele_array(dbp, numbufs, FTAG);
814	}
815	dnode_rele(dn, FTAG);
816	return (err);
817}
818
819void
820dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
821    const void *buf, dmu_tx_t *tx)
822{
823	dmu_buf_t **dbp;
824	int numbufs, i;
825
826	if (size == 0)
827		return;
828
829	VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
830	    FALSE, FTAG, &numbufs, &dbp));
831
832	for (i = 0; i < numbufs; i++) {
833		int tocpy;
834		int bufoff;
835		dmu_buf_t *db = dbp[i];
836
837		ASSERT(size > 0);
838
839		bufoff = offset - db->db_offset;
840		tocpy = (int)MIN(db->db_size - bufoff, size);
841
842		ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
843
844		if (tocpy == db->db_size)
845			dmu_buf_will_fill(db, tx);
846		else
847			dmu_buf_will_dirty(db, tx);
848
849		bcopy(buf, (char *)db->db_data + bufoff, tocpy);
850
851		if (tocpy == db->db_size)
852			dmu_buf_fill_done(db, tx);
853
854		offset += tocpy;
855		size -= tocpy;
856		buf = (char *)buf + tocpy;
857	}
858	dmu_buf_rele_array(dbp, numbufs, FTAG);
859}
860
861void
862dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
863    dmu_tx_t *tx)
864{
865	dmu_buf_t **dbp;
866	int numbufs, i;
867
868	if (size == 0)
869		return;
870
871	VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
872	    FALSE, FTAG, &numbufs, &dbp));
873
874	for (i = 0; i < numbufs; i++) {
875		dmu_buf_t *db = dbp[i];
876
877		dmu_buf_will_not_fill(db, tx);
878	}
879	dmu_buf_rele_array(dbp, numbufs, FTAG);
880}
881
882void
883dmu_write_embedded(objset_t *os, uint64_t object, uint64_t offset,
884    void *data, uint8_t etype, uint8_t comp, int uncompressed_size,
885    int compressed_size, int byteorder, dmu_tx_t *tx)
886{
887	dmu_buf_t *db;
888
889	ASSERT3U(etype, <, NUM_BP_EMBEDDED_TYPES);
890	ASSERT3U(comp, <, ZIO_COMPRESS_FUNCTIONS);
891	VERIFY0(dmu_buf_hold_noread(os, object, offset,
892	    FTAG, &db));
893
894	dmu_buf_write_embedded(db,
895	    data, (bp_embedded_type_t)etype, (enum zio_compress)comp,
896	    uncompressed_size, compressed_size, byteorder, tx);
897
898	dmu_buf_rele(db, FTAG);
899}
900
901/*
902 * DMU support for xuio
903 */
904kstat_t *xuio_ksp = NULL;
905
906int
907dmu_xuio_init(xuio_t *xuio, int nblk)
908{
909	dmu_xuio_t *priv;
910	uio_t *uio = &xuio->xu_uio;
911
912	uio->uio_iovcnt = nblk;
913	uio->uio_iov = kmem_zalloc(nblk * sizeof (iovec_t), KM_SLEEP);
914
915	priv = kmem_zalloc(sizeof (dmu_xuio_t), KM_SLEEP);
916	priv->cnt = nblk;
917	priv->bufs = kmem_zalloc(nblk * sizeof (arc_buf_t *), KM_SLEEP);
918	priv->iovp = uio->uio_iov;
919	XUIO_XUZC_PRIV(xuio) = priv;
920
921	if (XUIO_XUZC_RW(xuio) == UIO_READ)
922		XUIOSTAT_INCR(xuiostat_onloan_rbuf, nblk);
923	else
924		XUIOSTAT_INCR(xuiostat_onloan_wbuf, nblk);
925
926	return (0);
927}
928
929void
930dmu_xuio_fini(xuio_t *xuio)
931{
932	dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
933	int nblk = priv->cnt;
934
935	kmem_free(priv->iovp, nblk * sizeof (iovec_t));
936	kmem_free(priv->bufs, nblk * sizeof (arc_buf_t *));
937	kmem_free(priv, sizeof (dmu_xuio_t));
938
939	if (XUIO_XUZC_RW(xuio) == UIO_READ)
940		XUIOSTAT_INCR(xuiostat_onloan_rbuf, -nblk);
941	else
942		XUIOSTAT_INCR(xuiostat_onloan_wbuf, -nblk);
943}
944
945/*
946 * Initialize iov[priv->next] and priv->bufs[priv->next] with { off, n, abuf }
947 * and increase priv->next by 1.
948 */
949int
950dmu_xuio_add(xuio_t *xuio, arc_buf_t *abuf, offset_t off, size_t n)
951{
952	struct iovec *iov;
953	uio_t *uio = &xuio->xu_uio;
954	dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
955	int i = priv->next++;
956
957	ASSERT(i < priv->cnt);
958	ASSERT(off + n <= arc_buf_size(abuf));
959	iov = uio->uio_iov + i;
960	iov->iov_base = (char *)abuf->b_data + off;
961	iov->iov_len = n;
962	priv->bufs[i] = abuf;
963	return (0);
964}
965
966int
967dmu_xuio_cnt(xuio_t *xuio)
968{
969	dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
970	return (priv->cnt);
971}
972
973arc_buf_t *
974dmu_xuio_arcbuf(xuio_t *xuio, int i)
975{
976	dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
977
978	ASSERT(i < priv->cnt);
979	return (priv->bufs[i]);
980}
981
982void
983dmu_xuio_clear(xuio_t *xuio, int i)
984{
985	dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
986
987	ASSERT(i < priv->cnt);
988	priv->bufs[i] = NULL;
989}
990
991static void
992xuio_stat_init(void)
993{
994	xuio_ksp = kstat_create("zfs", 0, "xuio_stats", "misc",
995	    KSTAT_TYPE_NAMED, sizeof (xuio_stats) / sizeof (kstat_named_t),
996	    KSTAT_FLAG_VIRTUAL);
997	if (xuio_ksp != NULL) {
998		xuio_ksp->ks_data = &xuio_stats;
999		kstat_install(xuio_ksp);
1000	}
1001}
1002
1003static void
1004xuio_stat_fini(void)
1005{
1006	if (xuio_ksp != NULL) {
1007		kstat_delete(xuio_ksp);
1008		xuio_ksp = NULL;
1009	}
1010}
1011
1012void
1013xuio_stat_wbuf_copied()
1014{
1015	XUIOSTAT_BUMP(xuiostat_wbuf_copied);
1016}
1017
1018void
1019xuio_stat_wbuf_nocopy()
1020{
1021	XUIOSTAT_BUMP(xuiostat_wbuf_nocopy);
1022}
1023
1024#ifdef _KERNEL
1025int
1026dmu_read_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size)
1027{
1028	dmu_buf_t **dbp;
1029	int numbufs, i, err;
1030	xuio_t *xuio = NULL;
1031
1032	/*
1033	 * NB: we could do this block-at-a-time, but it's nice
1034	 * to be reading in parallel.
1035	 */
1036	err = dmu_buf_hold_array(os, object, uio->uio_loffset, size, TRUE, FTAG,
1037	    &numbufs, &dbp);
1038	if (err)
1039		return (err);
1040
1041#ifdef UIO_XUIO
1042	if (uio->uio_extflg == UIO_XUIO)
1043		xuio = (xuio_t *)uio;
1044#endif
1045
1046	for (i = 0; i < numbufs; i++) {
1047		int tocpy;
1048		int bufoff;
1049		dmu_buf_t *db = dbp[i];
1050
1051		ASSERT(size > 0);
1052
1053		bufoff = uio->uio_loffset - db->db_offset;
1054		tocpy = (int)MIN(db->db_size - bufoff, size);
1055
1056		if (xuio) {
1057			dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
1058			arc_buf_t *dbuf_abuf = dbi->db_buf;
1059			arc_buf_t *abuf = dbuf_loan_arcbuf(dbi);
1060			err = dmu_xuio_add(xuio, abuf, bufoff, tocpy);
1061			if (!err) {
1062				uio->uio_resid -= tocpy;
1063				uio->uio_loffset += tocpy;
1064			}
1065
1066			if (abuf == dbuf_abuf)
1067				XUIOSTAT_BUMP(xuiostat_rbuf_nocopy);
1068			else
1069				XUIOSTAT_BUMP(xuiostat_rbuf_copied);
1070		} else {
1071			err = uiomove((char *)db->db_data + bufoff, tocpy,
1072			    UIO_READ, uio);
1073		}
1074		if (err)
1075			break;
1076
1077		size -= tocpy;
1078	}
1079	dmu_buf_rele_array(dbp, numbufs, FTAG);
1080
1081	return (err);
1082}
1083
1084static int
1085dmu_write_uio_dnode(dnode_t *dn, uio_t *uio, uint64_t size, dmu_tx_t *tx)
1086{
1087	dmu_buf_t **dbp;
1088	int numbufs;
1089	int err = 0;
1090	int i;
1091
1092	err = dmu_buf_hold_array_by_dnode(dn, uio->uio_loffset, size,
1093	    FALSE, FTAG, &numbufs, &dbp, DMU_READ_PREFETCH);
1094	if (err)
1095		return (err);
1096
1097	for (i = 0; i < numbufs; i++) {
1098		int tocpy;
1099		int bufoff;
1100		dmu_buf_t *db = dbp[i];
1101
1102		ASSERT(size > 0);
1103
1104		bufoff = uio->uio_loffset - db->db_offset;
1105		tocpy = (int)MIN(db->db_size - bufoff, size);
1106
1107		ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
1108
1109		if (tocpy == db->db_size)
1110			dmu_buf_will_fill(db, tx);
1111		else
1112			dmu_buf_will_dirty(db, tx);
1113
1114		/*
1115		 * XXX uiomove could block forever (eg. nfs-backed
1116		 * pages).  There needs to be a uiolockdown() function
1117		 * to lock the pages in memory, so that uiomove won't
1118		 * block.
1119		 */
1120		err = uiomove((char *)db->db_data + bufoff, tocpy,
1121		    UIO_WRITE, uio);
1122
1123		if (tocpy == db->db_size)
1124			dmu_buf_fill_done(db, tx);
1125
1126		if (err)
1127			break;
1128
1129		size -= tocpy;
1130	}
1131
1132	dmu_buf_rele_array(dbp, numbufs, FTAG);
1133	return (err);
1134}
1135
1136int
1137dmu_write_uio_dbuf(dmu_buf_t *zdb, uio_t *uio, uint64_t size,
1138    dmu_tx_t *tx)
1139{
1140	dmu_buf_impl_t *db = (dmu_buf_impl_t *)zdb;
1141	dnode_t *dn;
1142	int err;
1143
1144	if (size == 0)
1145		return (0);
1146
1147	DB_DNODE_ENTER(db);
1148	dn = DB_DNODE(db);
1149	err = dmu_write_uio_dnode(dn, uio, size, tx);
1150	DB_DNODE_EXIT(db);
1151
1152	return (err);
1153}
1154
1155int
1156dmu_write_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size,
1157    dmu_tx_t *tx)
1158{
1159	dnode_t *dn;
1160	int err;
1161
1162	if (size == 0)
1163		return (0);
1164
1165	err = dnode_hold(os, object, FTAG, &dn);
1166	if (err)
1167		return (err);
1168
1169	err = dmu_write_uio_dnode(dn, uio, size, tx);
1170
1171	dnode_rele(dn, FTAG);
1172
1173	return (err);
1174}
1175
1176#ifdef sun
1177int
1178dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
1179    page_t *pp, dmu_tx_t *tx)
1180{
1181	dmu_buf_t **dbp;
1182	int numbufs, i;
1183	int err;
1184
1185	if (size == 0)
1186		return (0);
1187
1188	err = dmu_buf_hold_array(os, object, offset, size,
1189	    FALSE, FTAG, &numbufs, &dbp);
1190	if (err)
1191		return (err);
1192
1193	for (i = 0; i < numbufs; i++) {
1194		int tocpy, copied, thiscpy;
1195		int bufoff;
1196		dmu_buf_t *db = dbp[i];
1197		caddr_t va;
1198
1199		ASSERT(size > 0);
1200		ASSERT3U(db->db_size, >=, PAGESIZE);
1201
1202		bufoff = offset - db->db_offset;
1203		tocpy = (int)MIN(db->db_size - bufoff, size);
1204
1205		ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
1206
1207		if (tocpy == db->db_size)
1208			dmu_buf_will_fill(db, tx);
1209		else
1210			dmu_buf_will_dirty(db, tx);
1211
1212		for (copied = 0; copied < tocpy; copied += PAGESIZE) {
1213			ASSERT3U(pp->p_offset, ==, db->db_offset + bufoff);
1214			thiscpy = MIN(PAGESIZE, tocpy - copied);
1215			va = zfs_map_page(pp, S_READ);
1216			bcopy(va, (char *)db->db_data + bufoff, thiscpy);
1217			zfs_unmap_page(pp, va);
1218			pp = pp->p_next;
1219			bufoff += PAGESIZE;
1220		}
1221
1222		if (tocpy == db->db_size)
1223			dmu_buf_fill_done(db, tx);
1224
1225		offset += tocpy;
1226		size -= tocpy;
1227	}
1228	dmu_buf_rele_array(dbp, numbufs, FTAG);
1229	return (err);
1230}
1231
1232#else
1233
1234int
1235dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
1236    vm_page_t *ma, dmu_tx_t *tx)
1237{
1238	dmu_buf_t **dbp;
1239	struct sf_buf *sf;
1240	int numbufs, i;
1241	int err;
1242
1243	if (size == 0)
1244		return (0);
1245
1246	err = dmu_buf_hold_array(os, object, offset, size,
1247	    FALSE, FTAG, &numbufs, &dbp);
1248	if (err)
1249		return (err);
1250
1251	for (i = 0; i < numbufs; i++) {
1252		int tocpy, copied, thiscpy;
1253		int bufoff;
1254		dmu_buf_t *db = dbp[i];
1255		caddr_t va;
1256
1257		ASSERT(size > 0);
1258		ASSERT3U(db->db_size, >=, PAGESIZE);
1259
1260		bufoff = offset - db->db_offset;
1261		tocpy = (int)MIN(db->db_size - bufoff, size);
1262
1263		ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
1264
1265		if (tocpy == db->db_size)
1266			dmu_buf_will_fill(db, tx);
1267		else
1268			dmu_buf_will_dirty(db, tx);
1269
1270		for (copied = 0; copied < tocpy; copied += PAGESIZE) {
1271			ASSERT3U(ptoa((*ma)->pindex), ==, db->db_offset + bufoff);
1272			thiscpy = MIN(PAGESIZE, tocpy - copied);
1273			va = zfs_map_page(*ma, &sf);
1274			bcopy(va, (char *)db->db_data + bufoff, thiscpy);
1275			zfs_unmap_page(sf);
1276			ma += 1;
1277			bufoff += PAGESIZE;
1278		}
1279
1280		if (tocpy == db->db_size)
1281			dmu_buf_fill_done(db, tx);
1282
1283		offset += tocpy;
1284		size -= tocpy;
1285	}
1286	dmu_buf_rele_array(dbp, numbufs, FTAG);
1287	return (err);
1288}
1289#endif	/* sun */
1290#endif
1291
1292/*
1293 * Allocate a loaned anonymous arc buffer.
1294 */
1295arc_buf_t *
1296dmu_request_arcbuf(dmu_buf_t *handle, int size)
1297{
1298	dmu_buf_impl_t *db = (dmu_buf_impl_t *)handle;
1299
1300	return (arc_loan_buf(db->db_objset->os_spa, size));
1301}
1302
1303/*
1304 * Free a loaned arc buffer.
1305 */
1306void
1307dmu_return_arcbuf(arc_buf_t *buf)
1308{
1309	arc_return_buf(buf, FTAG);
1310	VERIFY(arc_buf_remove_ref(buf, FTAG));
1311}
1312
1313/*
1314 * When possible directly assign passed loaned arc buffer to a dbuf.
1315 * If this is not possible copy the contents of passed arc buf via
1316 * dmu_write().
1317 */
1318void
1319dmu_assign_arcbuf(dmu_buf_t *handle, uint64_t offset, arc_buf_t *buf,
1320    dmu_tx_t *tx)
1321{
1322	dmu_buf_impl_t *dbuf = (dmu_buf_impl_t *)handle;
1323	dnode_t *dn;
1324	dmu_buf_impl_t *db;
1325	uint32_t blksz = (uint32_t)arc_buf_size(buf);
1326	uint64_t blkid;
1327
1328	DB_DNODE_ENTER(dbuf);
1329	dn = DB_DNODE(dbuf);
1330	rw_enter(&dn->dn_struct_rwlock, RW_READER);
1331	blkid = dbuf_whichblock(dn, offset);
1332	VERIFY((db = dbuf_hold(dn, blkid, FTAG)) != NULL);
1333	rw_exit(&dn->dn_struct_rwlock);
1334	DB_DNODE_EXIT(dbuf);
1335
1336	/*
1337	 * We can only assign if the offset is aligned, the arc buf is the
1338	 * same size as the dbuf, and the dbuf is not metadata.  It
1339	 * can't be metadata because the loaned arc buf comes from the
1340	 * user-data kmem arena.
1341	 */
1342	if (offset == db->db.db_offset && blksz == db->db.db_size &&
1343	    DBUF_GET_BUFC_TYPE(db) == ARC_BUFC_DATA) {
1344		dbuf_assign_arcbuf(db, buf, tx);
1345		dbuf_rele(db, FTAG);
1346	} else {
1347		objset_t *os;
1348		uint64_t object;
1349
1350		DB_DNODE_ENTER(dbuf);
1351		dn = DB_DNODE(dbuf);
1352		os = dn->dn_objset;
1353		object = dn->dn_object;
1354		DB_DNODE_EXIT(dbuf);
1355
1356		dbuf_rele(db, FTAG);
1357		dmu_write(os, object, offset, blksz, buf->b_data, tx);
1358		dmu_return_arcbuf(buf);
1359		XUIOSTAT_BUMP(xuiostat_wbuf_copied);
1360	}
1361}
1362
1363typedef struct {
1364	dbuf_dirty_record_t	*dsa_dr;
1365	dmu_sync_cb_t		*dsa_done;
1366	zgd_t			*dsa_zgd;
1367	dmu_tx_t		*dsa_tx;
1368} dmu_sync_arg_t;
1369
1370/* ARGSUSED */
1371static void
1372dmu_sync_ready(zio_t *zio, arc_buf_t *buf, void *varg)
1373{
1374	dmu_sync_arg_t *dsa = varg;
1375	dmu_buf_t *db = dsa->dsa_zgd->zgd_db;
1376	blkptr_t *bp = zio->io_bp;
1377
1378	if (zio->io_error == 0) {
1379		if (BP_IS_HOLE(bp)) {
1380			/*
1381			 * A block of zeros may compress to a hole, but the
1382			 * block size still needs to be known for replay.
1383			 */
1384			BP_SET_LSIZE(bp, db->db_size);
1385		} else if (!BP_IS_EMBEDDED(bp)) {
1386			ASSERT(BP_GET_LEVEL(bp) == 0);
1387			bp->blk_fill = 1;
1388		}
1389	}
1390}
1391
1392static void
1393dmu_sync_late_arrival_ready(zio_t *zio)
1394{
1395	dmu_sync_ready(zio, NULL, zio->io_private);
1396}
1397
1398/* ARGSUSED */
1399static void
1400dmu_sync_done(zio_t *zio, arc_buf_t *buf, void *varg)
1401{
1402	dmu_sync_arg_t *dsa = varg;
1403	dbuf_dirty_record_t *dr = dsa->dsa_dr;
1404	dmu_buf_impl_t *db = dr->dr_dbuf;
1405
1406	mutex_enter(&db->db_mtx);
1407	ASSERT(dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC);
1408	if (zio->io_error == 0) {
1409		dr->dt.dl.dr_nopwrite = !!(zio->io_flags & ZIO_FLAG_NOPWRITE);
1410		if (dr->dt.dl.dr_nopwrite) {
1411			blkptr_t *bp = zio->io_bp;
1412			blkptr_t *bp_orig = &zio->io_bp_orig;
1413			uint8_t chksum = BP_GET_CHECKSUM(bp_orig);
1414
1415			ASSERT(BP_EQUAL(bp, bp_orig));
1416			ASSERT(zio->io_prop.zp_compress != ZIO_COMPRESS_OFF);
1417			ASSERT(zio_checksum_table[chksum].ci_dedup);
1418		}
1419		dr->dt.dl.dr_overridden_by = *zio->io_bp;
1420		dr->dt.dl.dr_override_state = DR_OVERRIDDEN;
1421		dr->dt.dl.dr_copies = zio->io_prop.zp_copies;
1422		if (BP_IS_HOLE(&dr->dt.dl.dr_overridden_by))
1423			BP_ZERO(&dr->dt.dl.dr_overridden_by);
1424	} else {
1425		dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
1426	}
1427	cv_broadcast(&db->db_changed);
1428	mutex_exit(&db->db_mtx);
1429
1430	dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
1431
1432	kmem_free(dsa, sizeof (*dsa));
1433}
1434
1435static void
1436dmu_sync_late_arrival_done(zio_t *zio)
1437{
1438	blkptr_t *bp = zio->io_bp;
1439	dmu_sync_arg_t *dsa = zio->io_private;
1440	blkptr_t *bp_orig = &zio->io_bp_orig;
1441
1442	if (zio->io_error == 0 && !BP_IS_HOLE(bp)) {
1443		/*
1444		 * If we didn't allocate a new block (i.e. ZIO_FLAG_NOPWRITE)
1445		 * then there is nothing to do here. Otherwise, free the
1446		 * newly allocated block in this txg.
1447		 */
1448		if (zio->io_flags & ZIO_FLAG_NOPWRITE) {
1449			ASSERT(BP_EQUAL(bp, bp_orig));
1450		} else {
1451			ASSERT(BP_IS_HOLE(bp_orig) || !BP_EQUAL(bp, bp_orig));
1452			ASSERT(zio->io_bp->blk_birth == zio->io_txg);
1453			ASSERT(zio->io_txg > spa_syncing_txg(zio->io_spa));
1454			zio_free(zio->io_spa, zio->io_txg, zio->io_bp);
1455		}
1456	}
1457
1458	dmu_tx_commit(dsa->dsa_tx);
1459
1460	dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
1461
1462	kmem_free(dsa, sizeof (*dsa));
1463}
1464
1465static int
1466dmu_sync_late_arrival(zio_t *pio, objset_t *os, dmu_sync_cb_t *done, zgd_t *zgd,
1467    zio_prop_t *zp, zbookmark_phys_t *zb)
1468{
1469	dmu_sync_arg_t *dsa;
1470	dmu_tx_t *tx;
1471
1472	tx = dmu_tx_create(os);
1473	dmu_tx_hold_space(tx, zgd->zgd_db->db_size);
1474	if (dmu_tx_assign(tx, TXG_WAIT) != 0) {
1475		dmu_tx_abort(tx);
1476		/* Make zl_get_data do txg_waited_synced() */
1477		return (SET_ERROR(EIO));
1478	}
1479
1480	dsa = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
1481	dsa->dsa_dr = NULL;
1482	dsa->dsa_done = done;
1483	dsa->dsa_zgd = zgd;
1484	dsa->dsa_tx = tx;
1485
1486	zio_nowait(zio_write(pio, os->os_spa, dmu_tx_get_txg(tx), zgd->zgd_bp,
1487	    zgd->zgd_db->db_data, zgd->zgd_db->db_size, zp,
1488	    dmu_sync_late_arrival_ready, NULL, dmu_sync_late_arrival_done, dsa,
1489	    ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_CANFAIL, zb));
1490
1491	return (0);
1492}
1493
1494/*
1495 * Intent log support: sync the block associated with db to disk.
1496 * N.B. and XXX: the caller is responsible for making sure that the
1497 * data isn't changing while dmu_sync() is writing it.
1498 *
1499 * Return values:
1500 *
1501 *	EEXIST: this txg has already been synced, so there's nothing to do.
1502 *		The caller should not log the write.
1503 *
1504 *	ENOENT: the block was dbuf_free_range()'d, so there's nothing to do.
1505 *		The caller should not log the write.
1506 *
1507 *	EALREADY: this block is already in the process of being synced.
1508 *		The caller should track its progress (somehow).
1509 *
1510 *	EIO: could not do the I/O.
1511 *		The caller should do a txg_wait_synced().
1512 *
1513 *	0: the I/O has been initiated.
1514 *		The caller should log this blkptr in the done callback.
1515 *		It is possible that the I/O will fail, in which case
1516 *		the error will be reported to the done callback and
1517 *		propagated to pio from zio_done().
1518 */
1519int
1520dmu_sync(zio_t *pio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd)
1521{
1522	blkptr_t *bp = zgd->zgd_bp;
1523	dmu_buf_impl_t *db = (dmu_buf_impl_t *)zgd->zgd_db;
1524	objset_t *os = db->db_objset;
1525	dsl_dataset_t *ds = os->os_dsl_dataset;
1526	dbuf_dirty_record_t *dr;
1527	dmu_sync_arg_t *dsa;
1528	zbookmark_phys_t zb;
1529	zio_prop_t zp;
1530	dnode_t *dn;
1531
1532	ASSERT(pio != NULL);
1533	ASSERT(txg != 0);
1534
1535	SET_BOOKMARK(&zb, ds->ds_object,
1536	    db->db.db_object, db->db_level, db->db_blkid);
1537
1538	DB_DNODE_ENTER(db);
1539	dn = DB_DNODE(db);
1540	dmu_write_policy(os, dn, db->db_level, WP_DMU_SYNC, &zp);
1541	DB_DNODE_EXIT(db);
1542
1543	/*
1544	 * If we're frozen (running ziltest), we always need to generate a bp.
1545	 */
1546	if (txg > spa_freeze_txg(os->os_spa))
1547		return (dmu_sync_late_arrival(pio, os, done, zgd, &zp, &zb));
1548
1549	/*
1550	 * Grabbing db_mtx now provides a barrier between dbuf_sync_leaf()
1551	 * and us.  If we determine that this txg is not yet syncing,
1552	 * but it begins to sync a moment later, that's OK because the
1553	 * sync thread will block in dbuf_sync_leaf() until we drop db_mtx.
1554	 */
1555	mutex_enter(&db->db_mtx);
1556
1557	if (txg <= spa_last_synced_txg(os->os_spa)) {
1558		/*
1559		 * This txg has already synced.  There's nothing to do.
1560		 */
1561		mutex_exit(&db->db_mtx);
1562		return (SET_ERROR(EEXIST));
1563	}
1564
1565	if (txg <= spa_syncing_txg(os->os_spa)) {
1566		/*
1567		 * This txg is currently syncing, so we can't mess with
1568		 * the dirty record anymore; just write a new log block.
1569		 */
1570		mutex_exit(&db->db_mtx);
1571		return (dmu_sync_late_arrival(pio, os, done, zgd, &zp, &zb));
1572	}
1573
1574	dr = db->db_last_dirty;
1575	while (dr && dr->dr_txg != txg)
1576		dr = dr->dr_next;
1577
1578	if (dr == NULL) {
1579		/*
1580		 * There's no dr for this dbuf, so it must have been freed.
1581		 * There's no need to log writes to freed blocks, so we're done.
1582		 */
1583		mutex_exit(&db->db_mtx);
1584		return (SET_ERROR(ENOENT));
1585	}
1586
1587	ASSERT(dr->dr_next == NULL || dr->dr_next->dr_txg < txg);
1588
1589	/*
1590	 * Assume the on-disk data is X, the current syncing data is Y,
1591	 * and the current in-memory data is Z (currently in dmu_sync).
1592	 * X and Z are identical but Y is has been modified. Normally,
1593	 * when X and Z are the same we will perform a nopwrite but if Y
1594	 * is different we must disable nopwrite since the resulting write
1595	 * of Y to disk can free the block containing X. If we allowed a
1596	 * nopwrite to occur the block pointing to Z would reference a freed
1597	 * block. Since this is a rare case we simplify this by disabling
1598	 * nopwrite if the current dmu_sync-ing dbuf has been modified in
1599	 * a previous transaction.
1600	 */
1601	if (dr->dr_next)
1602		zp.zp_nopwrite = B_FALSE;
1603
1604	ASSERT(dr->dr_txg == txg);
1605	if (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC ||
1606	    dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
1607		/*
1608		 * We have already issued a sync write for this buffer,
1609		 * or this buffer has already been synced.  It could not
1610		 * have been dirtied since, or we would have cleared the state.
1611		 */
1612		mutex_exit(&db->db_mtx);
1613		return (SET_ERROR(EALREADY));
1614	}
1615
1616	ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
1617	dr->dt.dl.dr_override_state = DR_IN_DMU_SYNC;
1618	mutex_exit(&db->db_mtx);
1619
1620	dsa = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
1621	dsa->dsa_dr = dr;
1622	dsa->dsa_done = done;
1623	dsa->dsa_zgd = zgd;
1624	dsa->dsa_tx = NULL;
1625
1626	zio_nowait(arc_write(pio, os->os_spa, txg,
1627	    bp, dr->dt.dl.dr_data, DBUF_IS_L2CACHEABLE(db),
1628	    DBUF_IS_L2COMPRESSIBLE(db), &zp, dmu_sync_ready,
1629	    NULL, dmu_sync_done, dsa, ZIO_PRIORITY_SYNC_WRITE,
1630	    ZIO_FLAG_CANFAIL, &zb));
1631
1632	return (0);
1633}
1634
1635int
1636dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size, int ibs,
1637	dmu_tx_t *tx)
1638{
1639	dnode_t *dn;
1640	int err;
1641
1642	err = dnode_hold(os, object, FTAG, &dn);
1643	if (err)
1644		return (err);
1645	err = dnode_set_blksz(dn, size, ibs, tx);
1646	dnode_rele(dn, FTAG);
1647	return (err);
1648}
1649
1650void
1651dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
1652	dmu_tx_t *tx)
1653{
1654	dnode_t *dn;
1655
1656	/*
1657	 * Send streams include each object's checksum function.  This
1658	 * check ensures that the receiving system can understand the
1659	 * checksum function transmitted.
1660	 */
1661	ASSERT3U(checksum, <, ZIO_CHECKSUM_LEGACY_FUNCTIONS);
1662
1663	VERIFY0(dnode_hold(os, object, FTAG, &dn));
1664	ASSERT3U(checksum, <, ZIO_CHECKSUM_FUNCTIONS);
1665	dn->dn_checksum = checksum;
1666	dnode_setdirty(dn, tx);
1667	dnode_rele(dn, FTAG);
1668}
1669
1670void
1671dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
1672	dmu_tx_t *tx)
1673{
1674	dnode_t *dn;
1675
1676	/*
1677	 * Send streams include each object's compression function.  This
1678	 * check ensures that the receiving system can understand the
1679	 * compression function transmitted.
1680	 */
1681	ASSERT3U(compress, <, ZIO_COMPRESS_LEGACY_FUNCTIONS);
1682
1683	VERIFY0(dnode_hold(os, object, FTAG, &dn));
1684	dn->dn_compress = compress;
1685	dnode_setdirty(dn, tx);
1686	dnode_rele(dn, FTAG);
1687}
1688
1689int zfs_mdcomp_disable = 0;
1690TUNABLE_INT("vfs.zfs.mdcomp_disable", &zfs_mdcomp_disable);
1691SYSCTL_INT(_vfs_zfs, OID_AUTO, mdcomp_disable, CTLFLAG_RW,
1692    &zfs_mdcomp_disable, 0, "Disable metadata compression");
1693
1694/*
1695 * When the "redundant_metadata" property is set to "most", only indirect
1696 * blocks of this level and higher will have an additional ditto block.
1697 */
1698int zfs_redundant_metadata_most_ditto_level = 2;
1699
1700void
1701dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp, zio_prop_t *zp)
1702{
1703	dmu_object_type_t type = dn ? dn->dn_type : DMU_OT_OBJSET;
1704	boolean_t ismd = (level > 0 || DMU_OT_IS_METADATA(type) ||
1705	    (wp & WP_SPILL));
1706	enum zio_checksum checksum = os->os_checksum;
1707	enum zio_compress compress = os->os_compress;
1708	enum zio_checksum dedup_checksum = os->os_dedup_checksum;
1709	boolean_t dedup = B_FALSE;
1710	boolean_t nopwrite = B_FALSE;
1711	boolean_t dedup_verify = os->os_dedup_verify;
1712	int copies = os->os_copies;
1713
1714	/*
1715	 * We maintain different write policies for each of the following
1716	 * types of data:
1717	 *	 1. metadata
1718	 *	 2. preallocated blocks (i.e. level-0 blocks of a dump device)
1719	 *	 3. all other level 0 blocks
1720	 */
1721	if (ismd) {
1722		/*
1723		 * XXX -- we should design a compression algorithm
1724		 * that specializes in arrays of bps.
1725		 */
1726		boolean_t lz4_ac = spa_feature_is_active(os->os_spa,
1727		    SPA_FEATURE_LZ4_COMPRESS);
1728
1729		if (zfs_mdcomp_disable) {
1730			compress = ZIO_COMPRESS_EMPTY;
1731		} else if (lz4_ac) {
1732			compress = ZIO_COMPRESS_LZ4;
1733		} else {
1734			compress = ZIO_COMPRESS_LZJB;
1735		}
1736
1737		/*
1738		 * Metadata always gets checksummed.  If the data
1739		 * checksum is multi-bit correctable, and it's not a
1740		 * ZBT-style checksum, then it's suitable for metadata
1741		 * as well.  Otherwise, the metadata checksum defaults
1742		 * to fletcher4.
1743		 */
1744		if (zio_checksum_table[checksum].ci_correctable < 1 ||
1745		    zio_checksum_table[checksum].ci_eck)
1746			checksum = ZIO_CHECKSUM_FLETCHER_4;
1747
1748		if (os->os_redundant_metadata == ZFS_REDUNDANT_METADATA_ALL ||
1749		    (os->os_redundant_metadata ==
1750		    ZFS_REDUNDANT_METADATA_MOST &&
1751		    (level >= zfs_redundant_metadata_most_ditto_level ||
1752		    DMU_OT_IS_METADATA(type) || (wp & WP_SPILL))))
1753			copies++;
1754	} else if (wp & WP_NOFILL) {
1755		ASSERT(level == 0);
1756
1757		/*
1758		 * If we're writing preallocated blocks, we aren't actually
1759		 * writing them so don't set any policy properties.  These
1760		 * blocks are currently only used by an external subsystem
1761		 * outside of zfs (i.e. dump) and not written by the zio
1762		 * pipeline.
1763		 */
1764		compress = ZIO_COMPRESS_OFF;
1765		checksum = ZIO_CHECKSUM_NOPARITY;
1766	} else {
1767		compress = zio_compress_select(dn->dn_compress, compress);
1768
1769		checksum = (dedup_checksum == ZIO_CHECKSUM_OFF) ?
1770		    zio_checksum_select(dn->dn_checksum, checksum) :
1771		    dedup_checksum;
1772
1773		/*
1774		 * Determine dedup setting.  If we are in dmu_sync(),
1775		 * we won't actually dedup now because that's all
1776		 * done in syncing context; but we do want to use the
1777		 * dedup checkum.  If the checksum is not strong
1778		 * enough to ensure unique signatures, force
1779		 * dedup_verify.
1780		 */
1781		if (dedup_checksum != ZIO_CHECKSUM_OFF) {
1782			dedup = (wp & WP_DMU_SYNC) ? B_FALSE : B_TRUE;
1783			if (!zio_checksum_table[checksum].ci_dedup)
1784				dedup_verify = B_TRUE;
1785		}
1786
1787		/*
1788		 * Enable nopwrite if we have a cryptographically secure
1789		 * checksum that has no known collisions (i.e. SHA-256)
1790		 * and compression is enabled.  We don't enable nopwrite if
1791		 * dedup is enabled as the two features are mutually exclusive.
1792		 */
1793		nopwrite = (!dedup && zio_checksum_table[checksum].ci_dedup &&
1794		    compress != ZIO_COMPRESS_OFF && zfs_nopwrite_enabled);
1795	}
1796
1797	zp->zp_checksum = checksum;
1798	zp->zp_compress = compress;
1799	zp->zp_type = (wp & WP_SPILL) ? dn->dn_bonustype : type;
1800	zp->zp_level = level;
1801	zp->zp_copies = MIN(copies, spa_max_replication(os->os_spa));
1802	zp->zp_dedup = dedup;
1803	zp->zp_dedup_verify = dedup && dedup_verify;
1804	zp->zp_nopwrite = nopwrite;
1805}
1806
1807int
1808dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole, uint64_t *off)
1809{
1810	dnode_t *dn;
1811	int i, err;
1812
1813	err = dnode_hold(os, object, FTAG, &dn);
1814	if (err)
1815		return (err);
1816	/*
1817	 * Sync any current changes before
1818	 * we go trundling through the block pointers.
1819	 */
1820	for (i = 0; i < TXG_SIZE; i++) {
1821		if (list_link_active(&dn->dn_dirty_link[i]))
1822			break;
1823	}
1824	if (i != TXG_SIZE) {
1825		dnode_rele(dn, FTAG);
1826		txg_wait_synced(dmu_objset_pool(os), 0);
1827		err = dnode_hold(os, object, FTAG, &dn);
1828		if (err)
1829			return (err);
1830	}
1831
1832	err = dnode_next_offset(dn, (hole ? DNODE_FIND_HOLE : 0), off, 1, 1, 0);
1833	dnode_rele(dn, FTAG);
1834
1835	return (err);
1836}
1837
1838void
1839dmu_object_info_from_dnode(dnode_t *dn, dmu_object_info_t *doi)
1840{
1841	dnode_phys_t *dnp;
1842
1843	rw_enter(&dn->dn_struct_rwlock, RW_READER);
1844	mutex_enter(&dn->dn_mtx);
1845
1846	dnp = dn->dn_phys;
1847
1848	doi->doi_data_block_size = dn->dn_datablksz;
1849	doi->doi_metadata_block_size = dn->dn_indblkshift ?
1850	    1ULL << dn->dn_indblkshift : 0;
1851	doi->doi_type = dn->dn_type;
1852	doi->doi_bonus_type = dn->dn_bonustype;
1853	doi->doi_bonus_size = dn->dn_bonuslen;
1854	doi->doi_indirection = dn->dn_nlevels;
1855	doi->doi_checksum = dn->dn_checksum;
1856	doi->doi_compress = dn->dn_compress;
1857	doi->doi_physical_blocks_512 = (DN_USED_BYTES(dnp) + 256) >> 9;
1858	doi->doi_max_offset = (dn->dn_maxblkid + 1) * dn->dn_datablksz;
1859	doi->doi_fill_count = 0;
1860	for (int i = 0; i < dnp->dn_nblkptr; i++)
1861		doi->doi_fill_count += BP_GET_FILL(&dnp->dn_blkptr[i]);
1862
1863	mutex_exit(&dn->dn_mtx);
1864	rw_exit(&dn->dn_struct_rwlock);
1865}
1866
1867/*
1868 * Get information on a DMU object.
1869 * If doi is NULL, just indicates whether the object exists.
1870 */
1871int
1872dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi)
1873{
1874	dnode_t *dn;
1875	int err = dnode_hold(os, object, FTAG, &dn);
1876
1877	if (err)
1878		return (err);
1879
1880	if (doi != NULL)
1881		dmu_object_info_from_dnode(dn, doi);
1882
1883	dnode_rele(dn, FTAG);
1884	return (0);
1885}
1886
1887/*
1888 * As above, but faster; can be used when you have a held dbuf in hand.
1889 */
1890void
1891dmu_object_info_from_db(dmu_buf_t *db_fake, dmu_object_info_t *doi)
1892{
1893	dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1894
1895	DB_DNODE_ENTER(db);
1896	dmu_object_info_from_dnode(DB_DNODE(db), doi);
1897	DB_DNODE_EXIT(db);
1898}
1899
1900/*
1901 * Faster still when you only care about the size.
1902 * This is specifically optimized for zfs_getattr().
1903 */
1904void
1905dmu_object_size_from_db(dmu_buf_t *db_fake, uint32_t *blksize,
1906    u_longlong_t *nblk512)
1907{
1908	dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1909	dnode_t *dn;
1910
1911	DB_DNODE_ENTER(db);
1912	dn = DB_DNODE(db);
1913
1914	*blksize = dn->dn_datablksz;
1915	/* add 1 for dnode space */
1916	*nblk512 = ((DN_USED_BYTES(dn->dn_phys) + SPA_MINBLOCKSIZE/2) >>
1917	    SPA_MINBLOCKSHIFT) + 1;
1918	DB_DNODE_EXIT(db);
1919}
1920
1921void
1922byteswap_uint64_array(void *vbuf, size_t size)
1923{
1924	uint64_t *buf = vbuf;
1925	size_t count = size >> 3;
1926	int i;
1927
1928	ASSERT((size & 7) == 0);
1929
1930	for (i = 0; i < count; i++)
1931		buf[i] = BSWAP_64(buf[i]);
1932}
1933
1934void
1935byteswap_uint32_array(void *vbuf, size_t size)
1936{
1937	uint32_t *buf = vbuf;
1938	size_t count = size >> 2;
1939	int i;
1940
1941	ASSERT((size & 3) == 0);
1942
1943	for (i = 0; i < count; i++)
1944		buf[i] = BSWAP_32(buf[i]);
1945}
1946
1947void
1948byteswap_uint16_array(void *vbuf, size_t size)
1949{
1950	uint16_t *buf = vbuf;
1951	size_t count = size >> 1;
1952	int i;
1953
1954	ASSERT((size & 1) == 0);
1955
1956	for (i = 0; i < count; i++)
1957		buf[i] = BSWAP_16(buf[i]);
1958}
1959
1960/* ARGSUSED */
1961void
1962byteswap_uint8_array(void *vbuf, size_t size)
1963{
1964}
1965
1966void
1967dmu_init(void)
1968{
1969	zfs_dbgmsg_init();
1970	sa_cache_init();
1971	xuio_stat_init();
1972	dmu_objset_init();
1973	dnode_init();
1974	dbuf_init();
1975	zfetch_init();
1976	zio_compress_init();
1977	l2arc_init();
1978	arc_init();
1979}
1980
1981void
1982dmu_fini(void)
1983{
1984	arc_fini(); /* arc depends on l2arc, so arc must go first */
1985	l2arc_fini();
1986	zfetch_fini();
1987	zio_compress_fini();
1988	dbuf_fini();
1989	dnode_fini();
1990	dmu_objset_fini();
1991	xuio_stat_fini();
1992	sa_cache_fini();
1993	zfs_dbgmsg_fini();
1994}
1995