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 2011 Nexenta Systems, Inc.  All rights reserved.
24 * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
25 * Copyright (c) 2014 Integros [integros.com]
26 */
27
28#include <sys/dmu.h>
29#include <sys/dmu_impl.h>
30#include <sys/dbuf.h>
31#include <sys/dmu_tx.h>
32#include <sys/dmu_objset.h>
33#include <sys/dsl_dataset.h>
34#include <sys/dsl_dir.h>
35#include <sys/dsl_pool.h>
36#include <sys/zap_impl.h>
37#include <sys/spa.h>
38#include <sys/sa.h>
39#include <sys/sa_impl.h>
40#include <sys/zfs_context.h>
41#include <sys/varargs.h>
42
43typedef void (*dmu_tx_hold_func_t)(dmu_tx_t *tx, struct dnode *dn,
44    uint64_t arg1, uint64_t arg2);
45
46
47dmu_tx_t *
48dmu_tx_create_dd(dsl_dir_t *dd)
49{
50	dmu_tx_t *tx = kmem_zalloc(sizeof (dmu_tx_t), KM_SLEEP);
51	tx->tx_dir = dd;
52	if (dd != NULL)
53		tx->tx_pool = dd->dd_pool;
54	list_create(&tx->tx_holds, sizeof (dmu_tx_hold_t),
55	    offsetof(dmu_tx_hold_t, txh_node));
56	list_create(&tx->tx_callbacks, sizeof (dmu_tx_callback_t),
57	    offsetof(dmu_tx_callback_t, dcb_node));
58	tx->tx_start = gethrtime();
59	return (tx);
60}
61
62dmu_tx_t *
63dmu_tx_create(objset_t *os)
64{
65	dmu_tx_t *tx = dmu_tx_create_dd(os->os_dsl_dataset->ds_dir);
66	tx->tx_objset = os;
67	return (tx);
68}
69
70dmu_tx_t *
71dmu_tx_create_assigned(struct dsl_pool *dp, uint64_t txg)
72{
73	dmu_tx_t *tx = dmu_tx_create_dd(NULL);
74
75	txg_verify(dp->dp_spa, txg);
76	tx->tx_pool = dp;
77	tx->tx_txg = txg;
78	tx->tx_anyobj = TRUE;
79
80	return (tx);
81}
82
83int
84dmu_tx_is_syncing(dmu_tx_t *tx)
85{
86	return (tx->tx_anyobj);
87}
88
89int
90dmu_tx_private_ok(dmu_tx_t *tx)
91{
92	return (tx->tx_anyobj);
93}
94
95static dmu_tx_hold_t *
96dmu_tx_hold_dnode_impl(dmu_tx_t *tx, dnode_t *dn, enum dmu_tx_hold_type type,
97    uint64_t arg1, uint64_t arg2)
98{
99	dmu_tx_hold_t *txh;
100
101	if (dn != NULL) {
102		(void) zfs_refcount_add(&dn->dn_holds, tx);
103		if (tx->tx_txg != 0) {
104			mutex_enter(&dn->dn_mtx);
105			/*
106			 * dn->dn_assigned_txg == tx->tx_txg doesn't pose a
107			 * problem, but there's no way for it to happen (for
108			 * now, at least).
109			 */
110			ASSERT(dn->dn_assigned_txg == 0);
111			dn->dn_assigned_txg = tx->tx_txg;
112			(void) zfs_refcount_add(&dn->dn_tx_holds, tx);
113			mutex_exit(&dn->dn_mtx);
114		}
115	}
116
117	txh = kmem_zalloc(sizeof (dmu_tx_hold_t), KM_SLEEP);
118	txh->txh_tx = tx;
119	txh->txh_dnode = dn;
120	zfs_refcount_create(&txh->txh_space_towrite);
121	zfs_refcount_create(&txh->txh_memory_tohold);
122	txh->txh_type = type;
123	txh->txh_arg1 = arg1;
124	txh->txh_arg2 = arg2;
125	list_insert_tail(&tx->tx_holds, txh);
126
127	return (txh);
128}
129
130static dmu_tx_hold_t *
131dmu_tx_hold_object_impl(dmu_tx_t *tx, objset_t *os, uint64_t object,
132    enum dmu_tx_hold_type type, uint64_t arg1, uint64_t arg2)
133{
134	dnode_t *dn = NULL;
135	dmu_tx_hold_t *txh;
136	int err;
137
138	if (object != DMU_NEW_OBJECT) {
139		err = dnode_hold(os, object, FTAG, &dn);
140		if (err != 0) {
141			tx->tx_err = err;
142			return (NULL);
143		}
144	}
145	txh = dmu_tx_hold_dnode_impl(tx, dn, type, arg1, arg2);
146	if (dn != NULL)
147		dnode_rele(dn, FTAG);
148	return (txh);
149}
150
151void
152dmu_tx_add_new_object(dmu_tx_t *tx, dnode_t *dn)
153{
154	/*
155	 * If we're syncing, they can manipulate any object anyhow, and
156	 * the hold on the dnode_t can cause problems.
157	 */
158	if (!dmu_tx_is_syncing(tx))
159		(void) dmu_tx_hold_dnode_impl(tx, dn, THT_NEWOBJECT, 0, 0);
160}
161
162/*
163 * This function reads specified data from disk.  The specified data will
164 * be needed to perform the transaction -- i.e, it will be read after
165 * we do dmu_tx_assign().  There are two reasons that we read the data now
166 * (before dmu_tx_assign()):
167 *
168 * 1. Reading it now has potentially better performance.  The transaction
169 * has not yet been assigned, so the TXG is not held open, and also the
170 * caller typically has less locks held when calling dmu_tx_hold_*() than
171 * after the transaction has been assigned.  This reduces the lock (and txg)
172 * hold times, thus reducing lock contention.
173 *
174 * 2. It is easier for callers (primarily the ZPL) to handle i/o errors
175 * that are detected before they start making changes to the DMU state
176 * (i.e. now).  Once the transaction has been assigned, and some DMU
177 * state has been changed, it can be difficult to recover from an i/o
178 * error (e.g. to undo the changes already made in memory at the DMU
179 * layer).  Typically code to do so does not exist in the caller -- it
180 * assumes that the data has already been cached and thus i/o errors are
181 * not possible.
182 *
183 * It has been observed that the i/o initiated here can be a performance
184 * problem, and it appears to be optional, because we don't look at the
185 * data which is read.  However, removing this read would only serve to
186 * move the work elsewhere (after the dmu_tx_assign()), where it may
187 * have a greater impact on performance (in addition to the impact on
188 * fault tolerance noted above).
189 */
190static int
191dmu_tx_check_ioerr(zio_t *zio, dnode_t *dn, int level, uint64_t blkid)
192{
193	int err;
194	dmu_buf_impl_t *db;
195
196	rw_enter(&dn->dn_struct_rwlock, RW_READER);
197	db = dbuf_hold_level(dn, level, blkid, FTAG);
198	rw_exit(&dn->dn_struct_rwlock);
199	if (db == NULL)
200		return (SET_ERROR(EIO));
201	err = dbuf_read(db, zio, DB_RF_CANFAIL | DB_RF_NOPREFETCH);
202	dbuf_rele(db, FTAG);
203	return (err);
204}
205
206/* ARGSUSED */
207static void
208dmu_tx_count_write(dmu_tx_hold_t *txh, uint64_t off, uint64_t len)
209{
210	dnode_t *dn = txh->txh_dnode;
211	int err = 0;
212
213	if (len == 0)
214		return;
215
216	(void) zfs_refcount_add_many(&txh->txh_space_towrite, len, FTAG);
217
218	if (zfs_refcount_count(&txh->txh_space_towrite) > 2 * DMU_MAX_ACCESS)
219		err = SET_ERROR(EFBIG);
220
221	if (dn == NULL)
222		return;
223
224	/*
225	 * For i/o error checking, read the blocks that will be needed
226	 * to perform the write: the first and last level-0 blocks (if
227	 * they are not aligned, i.e. if they are partial-block writes),
228	 * and all the level-1 blocks.
229	 */
230	if (dn->dn_maxblkid == 0) {
231		if (off < dn->dn_datablksz &&
232		    (off > 0 || len < dn->dn_datablksz)) {
233			err = dmu_tx_check_ioerr(NULL, dn, 0, 0);
234			if (err != 0) {
235				txh->txh_tx->tx_err = err;
236			}
237		}
238	} else {
239		zio_t *zio = zio_root(dn->dn_objset->os_spa,
240		    NULL, NULL, ZIO_FLAG_CANFAIL);
241
242		/* first level-0 block */
243		uint64_t start = off >> dn->dn_datablkshift;
244		if (P2PHASE(off, dn->dn_datablksz) || len < dn->dn_datablksz) {
245			err = dmu_tx_check_ioerr(zio, dn, 0, start);
246			if (err != 0) {
247				txh->txh_tx->tx_err = err;
248			}
249		}
250
251		/* last level-0 block */
252		uint64_t end = (off + len - 1) >> dn->dn_datablkshift;
253		if (end != start && end <= dn->dn_maxblkid &&
254		    P2PHASE(off + len, dn->dn_datablksz)) {
255			err = dmu_tx_check_ioerr(zio, dn, 0, end);
256			if (err != 0) {
257				txh->txh_tx->tx_err = err;
258			}
259		}
260
261		/* level-1 blocks */
262		if (dn->dn_nlevels > 1) {
263			int shft = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
264			for (uint64_t i = (start >> shft) + 1;
265			    i < end >> shft; i++) {
266				err = dmu_tx_check_ioerr(zio, dn, 1, i);
267				if (err != 0) {
268					txh->txh_tx->tx_err = err;
269				}
270			}
271		}
272
273		err = zio_wait(zio);
274		if (err != 0) {
275			txh->txh_tx->tx_err = err;
276		}
277	}
278}
279
280static void
281dmu_tx_count_dnode(dmu_tx_hold_t *txh)
282{
283	(void) zfs_refcount_add_many(&txh->txh_space_towrite, DNODE_MIN_SIZE,
284	    FTAG);
285}
286
287void
288dmu_tx_hold_write(dmu_tx_t *tx, uint64_t object, uint64_t off, int len)
289{
290	dmu_tx_hold_t *txh;
291
292	ASSERT0(tx->tx_txg);
293	ASSERT3U(len, <=, DMU_MAX_ACCESS);
294	ASSERT(len == 0 || UINT64_MAX - off >= len - 1);
295
296	txh = dmu_tx_hold_object_impl(tx, tx->tx_objset,
297	    object, THT_WRITE, off, len);
298	if (txh != NULL) {
299		dmu_tx_count_write(txh, off, len);
300		dmu_tx_count_dnode(txh);
301	}
302}
303
304void
305dmu_tx_hold_remap_l1indirect(dmu_tx_t *tx, uint64_t object)
306{
307	dmu_tx_hold_t *txh;
308
309	ASSERT(tx->tx_txg == 0);
310	txh = dmu_tx_hold_object_impl(tx, tx->tx_objset,
311	    object, THT_WRITE, 0, 0);
312	if (txh == NULL)
313		return;
314
315	dnode_t *dn = txh->txh_dnode;
316	(void) zfs_refcount_add_many(&txh->txh_space_towrite,
317	    1ULL << dn->dn_indblkshift, FTAG);
318	dmu_tx_count_dnode(txh);
319}
320
321void
322dmu_tx_hold_write_by_dnode(dmu_tx_t *tx, dnode_t *dn, uint64_t off, int len)
323{
324	dmu_tx_hold_t *txh;
325
326	ASSERT0(tx->tx_txg);
327	ASSERT3U(len, <=, DMU_MAX_ACCESS);
328	ASSERT(len == 0 || UINT64_MAX - off >= len - 1);
329
330	txh = dmu_tx_hold_dnode_impl(tx, dn, THT_WRITE, off, len);
331	if (txh != NULL) {
332		dmu_tx_count_write(txh, off, len);
333		dmu_tx_count_dnode(txh);
334	}
335}
336
337/*
338 * This function marks the transaction as being a "net free".  The end
339 * result is that refquotas will be disabled for this transaction, and
340 * this transaction will be able to use half of the pool space overhead
341 * (see dsl_pool_adjustedsize()).  Therefore this function should only
342 * be called for transactions that we expect will not cause a net increase
343 * in the amount of space used (but it's OK if that is occasionally not true).
344 */
345void
346dmu_tx_mark_netfree(dmu_tx_t *tx)
347{
348	tx->tx_netfree = B_TRUE;
349}
350
351static void
352dmu_tx_hold_free_impl(dmu_tx_hold_t *txh, uint64_t off, uint64_t len)
353{
354	dmu_tx_t *tx;
355	dnode_t *dn;
356	int err;
357
358	tx = txh->txh_tx;
359	ASSERT(tx->tx_txg == 0);
360
361	dn = txh->txh_dnode;
362	dmu_tx_count_dnode(txh);
363
364	if (off >= (dn->dn_maxblkid + 1) * dn->dn_datablksz)
365		return;
366	if (len == DMU_OBJECT_END)
367		len = (dn->dn_maxblkid + 1) * dn->dn_datablksz - off;
368
369	/*
370	 * For i/o error checking, we read the first and last level-0
371	 * blocks if they are not aligned, and all the level-1 blocks.
372	 *
373	 * Note:  dbuf_free_range() assumes that we have not instantiated
374	 * any level-0 dbufs that will be completely freed.  Therefore we must
375	 * exercise care to not read or count the first and last blocks
376	 * if they are blocksize-aligned.
377	 */
378	if (dn->dn_datablkshift == 0) {
379		if (off != 0 || len < dn->dn_datablksz)
380			dmu_tx_count_write(txh, 0, dn->dn_datablksz);
381	} else {
382		/* first block will be modified if it is not aligned */
383		if (!IS_P2ALIGNED(off, 1 << dn->dn_datablkshift))
384			dmu_tx_count_write(txh, off, 1);
385		/* last block will be modified if it is not aligned */
386		if (!IS_P2ALIGNED(off + len, 1 << dn->dn_datablkshift))
387			dmu_tx_count_write(txh, off + len, 1);
388	}
389
390	/*
391	 * Check level-1 blocks.
392	 */
393	if (dn->dn_nlevels > 1) {
394		int shift = dn->dn_datablkshift + dn->dn_indblkshift -
395		    SPA_BLKPTRSHIFT;
396		uint64_t start = off >> shift;
397		uint64_t end = (off + len) >> shift;
398
399		ASSERT(dn->dn_indblkshift != 0);
400
401		/*
402		 * dnode_reallocate() can result in an object with indirect
403		 * blocks having an odd data block size.  In this case,
404		 * just check the single block.
405		 */
406		if (dn->dn_datablkshift == 0)
407			start = end = 0;
408
409		zio_t *zio = zio_root(tx->tx_pool->dp_spa,
410		    NULL, NULL, ZIO_FLAG_CANFAIL);
411		for (uint64_t i = start; i <= end; i++) {
412			uint64_t ibyte = i << shift;
413			err = dnode_next_offset(dn, 0, &ibyte, 2, 1, 0);
414			i = ibyte >> shift;
415			if (err == ESRCH || i > end)
416				break;
417			if (err != 0) {
418				tx->tx_err = err;
419				(void) zio_wait(zio);
420				return;
421			}
422
423			(void) zfs_refcount_add_many(&txh->txh_memory_tohold,
424			    1 << dn->dn_indblkshift, FTAG);
425
426			err = dmu_tx_check_ioerr(zio, dn, 1, i);
427			if (err != 0) {
428				tx->tx_err = err;
429				(void) zio_wait(zio);
430				return;
431			}
432		}
433		err = zio_wait(zio);
434		if (err != 0) {
435			tx->tx_err = err;
436			return;
437		}
438	}
439}
440
441void
442dmu_tx_hold_free(dmu_tx_t *tx, uint64_t object, uint64_t off, uint64_t len)
443{
444	dmu_tx_hold_t *txh;
445
446	txh = dmu_tx_hold_object_impl(tx, tx->tx_objset,
447	    object, THT_FREE, off, len);
448	if (txh != NULL)
449		(void) dmu_tx_hold_free_impl(txh, off, len);
450}
451
452void
453dmu_tx_hold_free_by_dnode(dmu_tx_t *tx, dnode_t *dn, uint64_t off, uint64_t len)
454{
455	dmu_tx_hold_t *txh;
456
457	txh = dmu_tx_hold_dnode_impl(tx, dn, THT_FREE, off, len);
458	if (txh != NULL)
459		(void) dmu_tx_hold_free_impl(txh, off, len);
460}
461
462static void
463dmu_tx_hold_zap_impl(dmu_tx_hold_t *txh, const char *name)
464{
465	dmu_tx_t *tx = txh->txh_tx;
466	dnode_t *dn;
467	int err;
468
469	ASSERT(tx->tx_txg == 0);
470
471	dn = txh->txh_dnode;
472
473	dmu_tx_count_dnode(txh);
474
475	/*
476	 * Modifying a almost-full microzap is around the worst case (128KB)
477	 *
478	 * If it is a fat zap, the worst case would be 7*16KB=112KB:
479	 * - 3 blocks overwritten: target leaf, ptrtbl block, header block
480	 * - 4 new blocks written if adding:
481	 *    - 2 blocks for possibly split leaves,
482	 *    - 2 grown ptrtbl blocks
483	 */
484	(void) zfs_refcount_add_many(&txh->txh_space_towrite,
485	    MZAP_MAX_BLKSZ, FTAG);
486
487	if (dn == NULL)
488		return;
489
490	ASSERT3P(DMU_OT_BYTESWAP(dn->dn_type), ==, DMU_BSWAP_ZAP);
491
492	if (dn->dn_maxblkid == 0 || name == NULL) {
493		/*
494		 * This is a microzap (only one block), or we don't know
495		 * the name.  Check the first block for i/o errors.
496		 */
497		err = dmu_tx_check_ioerr(NULL, dn, 0, 0);
498		if (err != 0) {
499			tx->tx_err = err;
500		}
501	} else {
502		/*
503		 * Access the name so that we'll check for i/o errors to
504		 * the leaf blocks, etc.  We ignore ENOENT, as this name
505		 * may not yet exist.
506		 */
507		err = zap_lookup_by_dnode(dn, name, 8, 0, NULL);
508		if (err == EIO || err == ECKSUM || err == ENXIO) {
509			tx->tx_err = err;
510		}
511	}
512}
513
514void
515dmu_tx_hold_zap(dmu_tx_t *tx, uint64_t object, int add, const char *name)
516{
517	dmu_tx_hold_t *txh;
518
519	ASSERT0(tx->tx_txg);
520
521	txh = dmu_tx_hold_object_impl(tx, tx->tx_objset,
522	    object, THT_ZAP, add, (uintptr_t)name);
523	if (txh != NULL)
524		dmu_tx_hold_zap_impl(txh, name);
525}
526
527void
528dmu_tx_hold_zap_by_dnode(dmu_tx_t *tx, dnode_t *dn, int add, const char *name)
529{
530	dmu_tx_hold_t *txh;
531
532	ASSERT0(tx->tx_txg);
533	ASSERT(dn != NULL);
534
535	txh = dmu_tx_hold_dnode_impl(tx, dn, THT_ZAP, add, (uintptr_t)name);
536	if (txh != NULL)
537		dmu_tx_hold_zap_impl(txh, name);
538}
539
540void
541dmu_tx_hold_bonus(dmu_tx_t *tx, uint64_t object)
542{
543	dmu_tx_hold_t *txh;
544
545	ASSERT(tx->tx_txg == 0);
546
547	txh = dmu_tx_hold_object_impl(tx, tx->tx_objset,
548	    object, THT_BONUS, 0, 0);
549	if (txh)
550		dmu_tx_count_dnode(txh);
551}
552
553void
554dmu_tx_hold_bonus_by_dnode(dmu_tx_t *tx, dnode_t *dn)
555{
556	dmu_tx_hold_t *txh;
557
558	ASSERT0(tx->tx_txg);
559
560	txh = dmu_tx_hold_dnode_impl(tx, dn, THT_BONUS, 0, 0);
561	if (txh)
562		dmu_tx_count_dnode(txh);
563}
564
565void
566dmu_tx_hold_space(dmu_tx_t *tx, uint64_t space)
567{
568	dmu_tx_hold_t *txh;
569	ASSERT(tx->tx_txg == 0);
570
571	txh = dmu_tx_hold_object_impl(tx, tx->tx_objset,
572	    DMU_NEW_OBJECT, THT_SPACE, space, 0);
573
574	(void) zfs_refcount_add_many(&txh->txh_space_towrite, space, FTAG);
575}
576
577#ifdef ZFS_DEBUG
578void
579dmu_tx_dirty_buf(dmu_tx_t *tx, dmu_buf_impl_t *db)
580{
581	boolean_t match_object = B_FALSE;
582	boolean_t match_offset = B_FALSE;
583
584	DB_DNODE_ENTER(db);
585	dnode_t *dn = DB_DNODE(db);
586	ASSERT(tx->tx_txg != 0);
587	ASSERT(tx->tx_objset == NULL || dn->dn_objset == tx->tx_objset);
588	ASSERT3U(dn->dn_object, ==, db->db.db_object);
589
590	if (tx->tx_anyobj) {
591		DB_DNODE_EXIT(db);
592		return;
593	}
594
595	/* XXX No checking on the meta dnode for now */
596	if (db->db.db_object == DMU_META_DNODE_OBJECT) {
597		DB_DNODE_EXIT(db);
598		return;
599	}
600
601	for (dmu_tx_hold_t *txh = list_head(&tx->tx_holds); txh != NULL;
602	    txh = list_next(&tx->tx_holds, txh)) {
603		ASSERT(dn == NULL || dn->dn_assigned_txg == tx->tx_txg);
604		if (txh->txh_dnode == dn && txh->txh_type != THT_NEWOBJECT)
605			match_object = TRUE;
606		if (txh->txh_dnode == NULL || txh->txh_dnode == dn) {
607			int datablkshift = dn->dn_datablkshift ?
608			    dn->dn_datablkshift : SPA_MAXBLOCKSHIFT;
609			int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
610			int shift = datablkshift + epbs * db->db_level;
611			uint64_t beginblk = shift >= 64 ? 0 :
612			    (txh->txh_arg1 >> shift);
613			uint64_t endblk = shift >= 64 ? 0 :
614			    ((txh->txh_arg1 + txh->txh_arg2 - 1) >> shift);
615			uint64_t blkid = db->db_blkid;
616
617			/* XXX txh_arg2 better not be zero... */
618
619			dprintf("found txh type %x beginblk=%llx endblk=%llx\n",
620			    txh->txh_type, beginblk, endblk);
621
622			switch (txh->txh_type) {
623			case THT_WRITE:
624				if (blkid >= beginblk && blkid <= endblk)
625					match_offset = TRUE;
626				/*
627				 * We will let this hold work for the bonus
628				 * or spill buffer so that we don't need to
629				 * hold it when creating a new object.
630				 */
631				if (blkid == DMU_BONUS_BLKID ||
632				    blkid == DMU_SPILL_BLKID)
633					match_offset = TRUE;
634				/*
635				 * They might have to increase nlevels,
636				 * thus dirtying the new TLIBs.  Or the
637				 * might have to change the block size,
638				 * thus dirying the new lvl=0 blk=0.
639				 */
640				if (blkid == 0)
641					match_offset = TRUE;
642				break;
643			case THT_FREE:
644				/*
645				 * We will dirty all the level 1 blocks in
646				 * the free range and perhaps the first and
647				 * last level 0 block.
648				 */
649				if (blkid >= beginblk && (blkid <= endblk ||
650				    txh->txh_arg2 == DMU_OBJECT_END))
651					match_offset = TRUE;
652				break;
653			case THT_SPILL:
654				if (blkid == DMU_SPILL_BLKID)
655					match_offset = TRUE;
656				break;
657			case THT_BONUS:
658				if (blkid == DMU_BONUS_BLKID)
659					match_offset = TRUE;
660				break;
661			case THT_ZAP:
662				match_offset = TRUE;
663				break;
664			case THT_NEWOBJECT:
665				match_object = TRUE;
666				break;
667			default:
668				ASSERT(!"bad txh_type");
669			}
670		}
671		if (match_object && match_offset) {
672			DB_DNODE_EXIT(db);
673			return;
674		}
675	}
676	DB_DNODE_EXIT(db);
677	panic("dirtying dbuf obj=%llx lvl=%u blkid=%llx but not tx_held\n",
678	    (u_longlong_t)db->db.db_object, db->db_level,
679	    (u_longlong_t)db->db_blkid);
680}
681#endif
682
683/*
684 * If we can't do 10 iops, something is wrong.  Let us go ahead
685 * and hit zfs_dirty_data_max.
686 */
687hrtime_t zfs_delay_max_ns = MSEC2NSEC(100);
688int zfs_delay_resolution_ns = 100 * 1000; /* 100 microseconds */
689
690/*
691 * We delay transactions when we've determined that the backend storage
692 * isn't able to accommodate the rate of incoming writes.
693 *
694 * If there is already a transaction waiting, we delay relative to when
695 * that transaction finishes waiting.  This way the calculated min_time
696 * is independent of the number of threads concurrently executing
697 * transactions.
698 *
699 * If we are the only waiter, wait relative to when the transaction
700 * started, rather than the current time.  This credits the transaction for
701 * "time already served", e.g. reading indirect blocks.
702 *
703 * The minimum time for a transaction to take is calculated as:
704 *     min_time = scale * (dirty - min) / (max - dirty)
705 *     min_time is then capped at zfs_delay_max_ns.
706 *
707 * The delay has two degrees of freedom that can be adjusted via tunables.
708 * The percentage of dirty data at which we start to delay is defined by
709 * zfs_delay_min_dirty_percent. This should typically be at or above
710 * zfs_vdev_async_write_active_max_dirty_percent so that we only start to
711 * delay after writing at full speed has failed to keep up with the incoming
712 * write rate. The scale of the curve is defined by zfs_delay_scale. Roughly
713 * speaking, this variable determines the amount of delay at the midpoint of
714 * the curve.
715 *
716 * delay
717 *  10ms +-------------------------------------------------------------*+
718 *       |                                                             *|
719 *   9ms +                                                             *+
720 *       |                                                             *|
721 *   8ms +                                                             *+
722 *       |                                                            * |
723 *   7ms +                                                            * +
724 *       |                                                            * |
725 *   6ms +                                                            * +
726 *       |                                                            * |
727 *   5ms +                                                           *  +
728 *       |                                                           *  |
729 *   4ms +                                                           *  +
730 *       |                                                           *  |
731 *   3ms +                                                          *   +
732 *       |                                                          *   |
733 *   2ms +                                              (midpoint) *    +
734 *       |                                                  |    **     |
735 *   1ms +                                                  v ***       +
736 *       |             zfs_delay_scale ---------->     ********         |
737 *     0 +-------------------------------------*********----------------+
738 *       0%                    <- zfs_dirty_data_max ->               100%
739 *
740 * Note that since the delay is added to the outstanding time remaining on the
741 * most recent transaction, the delay is effectively the inverse of IOPS.
742 * Here the midpoint of 500us translates to 2000 IOPS. The shape of the curve
743 * was chosen such that small changes in the amount of accumulated dirty data
744 * in the first 3/4 of the curve yield relatively small differences in the
745 * amount of delay.
746 *
747 * The effects can be easier to understand when the amount of delay is
748 * represented on a log scale:
749 *
750 * delay
751 * 100ms +-------------------------------------------------------------++
752 *       +                                                              +
753 *       |                                                              |
754 *       +                                                             *+
755 *  10ms +                                                             *+
756 *       +                                                           ** +
757 *       |                                              (midpoint)  **  |
758 *       +                                                  |     **    +
759 *   1ms +                                                  v ****      +
760 *       +             zfs_delay_scale ---------->        *****         +
761 *       |                                             ****             |
762 *       +                                          ****                +
763 * 100us +                                        **                    +
764 *       +                                       *                      +
765 *       |                                      *                       |
766 *       +                                     *                        +
767 *  10us +                                     *                        +
768 *       +                                                              +
769 *       |                                                              |
770 *       +                                                              +
771 *       +--------------------------------------------------------------+
772 *       0%                    <- zfs_dirty_data_max ->               100%
773 *
774 * Note here that only as the amount of dirty data approaches its limit does
775 * the delay start to increase rapidly. The goal of a properly tuned system
776 * should be to keep the amount of dirty data out of that range by first
777 * ensuring that the appropriate limits are set for the I/O scheduler to reach
778 * optimal throughput on the backend storage, and then by changing the value
779 * of zfs_delay_scale to increase the steepness of the curve.
780 */
781static void
782dmu_tx_delay(dmu_tx_t *tx, uint64_t dirty)
783{
784	dsl_pool_t *dp = tx->tx_pool;
785	uint64_t delay_min_bytes =
786	    zfs_dirty_data_max * zfs_delay_min_dirty_percent / 100;
787	hrtime_t wakeup, min_tx_time, now;
788
789	if (dirty <= delay_min_bytes)
790		return;
791
792	/*
793	 * The caller has already waited until we are under the max.
794	 * We make them pass us the amount of dirty data so we don't
795	 * have to handle the case of it being >= the max, which could
796	 * cause a divide-by-zero if it's == the max.
797	 */
798	ASSERT3U(dirty, <, zfs_dirty_data_max);
799
800	now = gethrtime();
801	min_tx_time = zfs_delay_scale *
802	    (dirty - delay_min_bytes) / (zfs_dirty_data_max - dirty);
803	if (now > tx->tx_start + min_tx_time)
804		return;
805
806	min_tx_time = MIN(min_tx_time, zfs_delay_max_ns);
807
808	DTRACE_PROBE3(delay__mintime, dmu_tx_t *, tx, uint64_t, dirty,
809	    uint64_t, min_tx_time);
810
811	mutex_enter(&dp->dp_lock);
812	wakeup = MAX(tx->tx_start + min_tx_time,
813	    dp->dp_last_wakeup + min_tx_time);
814	dp->dp_last_wakeup = wakeup;
815	mutex_exit(&dp->dp_lock);
816
817#ifdef _KERNEL
818	mutex_enter(&curthread->t_delay_lock);
819	while (cv_timedwait_hires(&curthread->t_delay_cv,
820	    &curthread->t_delay_lock, wakeup, zfs_delay_resolution_ns,
821	    CALLOUT_FLAG_ABSOLUTE | CALLOUT_FLAG_ROUNDUP) > 0)
822		continue;
823	mutex_exit(&curthread->t_delay_lock);
824#else
825	hrtime_t delta = wakeup - gethrtime();
826	struct timespec ts;
827	ts.tv_sec = delta / NANOSEC;
828	ts.tv_nsec = delta % NANOSEC;
829	(void) nanosleep(&ts, NULL);
830#endif
831}
832
833/*
834 * This routine attempts to assign the transaction to a transaction group.
835 * To do so, we must determine if there is sufficient free space on disk.
836 *
837 * If this is a "netfree" transaction (i.e. we called dmu_tx_mark_netfree()
838 * on it), then it is assumed that there is sufficient free space,
839 * unless there's insufficient slop space in the pool (see the comment
840 * above spa_slop_shift in spa_misc.c).
841 *
842 * If it is not a "netfree" transaction, then if the data already on disk
843 * is over the allowed usage (e.g. quota), this will fail with EDQUOT or
844 * ENOSPC.  Otherwise, if the current rough estimate of pending changes,
845 * plus the rough estimate of this transaction's changes, may exceed the
846 * allowed usage, then this will fail with ERESTART, which will cause the
847 * caller to wait for the pending changes to be written to disk (by waiting
848 * for the next TXG to open), and then check the space usage again.
849 *
850 * The rough estimate of pending changes is comprised of the sum of:
851 *
852 *  - this transaction's holds' txh_space_towrite
853 *
854 *  - dd_tempreserved[], which is the sum of in-flight transactions'
855 *    holds' txh_space_towrite (i.e. those transactions that have called
856 *    dmu_tx_assign() but not yet called dmu_tx_commit()).
857 *
858 *  - dd_space_towrite[], which is the amount of dirtied dbufs.
859 *
860 * Note that all of these values are inflated by spa_get_worst_case_asize(),
861 * which means that we may get ERESTART well before we are actually in danger
862 * of running out of space, but this also mitigates any small inaccuracies
863 * in the rough estimate (e.g. txh_space_towrite doesn't take into account
864 * indirect blocks, and dd_space_towrite[] doesn't take into account changes
865 * to the MOS).
866 *
867 * Note that due to this algorithm, it is possible to exceed the allowed
868 * usage by one transaction.  Also, as we approach the allowed usage,
869 * we will allow a very limited amount of changes into each TXG, thus
870 * decreasing performance.
871 */
872static int
873dmu_tx_try_assign(dmu_tx_t *tx, uint64_t txg_how)
874{
875	spa_t *spa = tx->tx_pool->dp_spa;
876
877	ASSERT0(tx->tx_txg);
878
879	if (tx->tx_err)
880		return (tx->tx_err);
881
882	if (spa_suspended(spa)) {
883		/*
884		 * If the user has indicated a blocking failure mode
885		 * then return ERESTART which will block in dmu_tx_wait().
886		 * Otherwise, return EIO so that an error can get
887		 * propagated back to the VOP calls.
888		 *
889		 * Note that we always honor the txg_how flag regardless
890		 * of the failuremode setting.
891		 */
892		if (spa_get_failmode(spa) == ZIO_FAILURE_MODE_CONTINUE &&
893		    !(txg_how & TXG_WAIT))
894			return (SET_ERROR(EIO));
895
896		return (SET_ERROR(ERESTART));
897	}
898
899	if (!tx->tx_dirty_delayed &&
900	    dsl_pool_need_dirty_delay(tx->tx_pool)) {
901		tx->tx_wait_dirty = B_TRUE;
902		return (SET_ERROR(ERESTART));
903	}
904
905	tx->tx_txg = txg_hold_open(tx->tx_pool, &tx->tx_txgh);
906	tx->tx_needassign_txh = NULL;
907
908	/*
909	 * NB: No error returns are allowed after txg_hold_open, but
910	 * before processing the dnode holds, due to the
911	 * dmu_tx_unassign() logic.
912	 */
913
914	uint64_t towrite = 0;
915	uint64_t tohold = 0;
916	for (dmu_tx_hold_t *txh = list_head(&tx->tx_holds); txh != NULL;
917	    txh = list_next(&tx->tx_holds, txh)) {
918		dnode_t *dn = txh->txh_dnode;
919		if (dn != NULL) {
920			mutex_enter(&dn->dn_mtx);
921			if (dn->dn_assigned_txg == tx->tx_txg - 1) {
922				mutex_exit(&dn->dn_mtx);
923				tx->tx_needassign_txh = txh;
924				return (SET_ERROR(ERESTART));
925			}
926			if (dn->dn_assigned_txg == 0)
927				dn->dn_assigned_txg = tx->tx_txg;
928			ASSERT3U(dn->dn_assigned_txg, ==, tx->tx_txg);
929			(void) zfs_refcount_add(&dn->dn_tx_holds, tx);
930			mutex_exit(&dn->dn_mtx);
931		}
932		towrite += zfs_refcount_count(&txh->txh_space_towrite);
933		tohold += zfs_refcount_count(&txh->txh_memory_tohold);
934	}
935
936	/* needed allocation: worst-case estimate of write space */
937	uint64_t asize = spa_get_worst_case_asize(tx->tx_pool->dp_spa, towrite);
938	/* calculate memory footprint estimate */
939	uint64_t memory = towrite + tohold;
940
941	if (tx->tx_dir != NULL && asize != 0) {
942		int err = dsl_dir_tempreserve_space(tx->tx_dir, memory,
943		    asize, tx->tx_netfree, &tx->tx_tempreserve_cookie, tx);
944		if (err != 0)
945			return (err);
946	}
947
948	return (0);
949}
950
951static void
952dmu_tx_unassign(dmu_tx_t *tx)
953{
954	if (tx->tx_txg == 0)
955		return;
956
957	txg_rele_to_quiesce(&tx->tx_txgh);
958
959	/*
960	 * Walk the transaction's hold list, removing the hold on the
961	 * associated dnode, and notifying waiters if the refcount drops to 0.
962	 */
963	for (dmu_tx_hold_t *txh = list_head(&tx->tx_holds);
964	    txh != tx->tx_needassign_txh;
965	    txh = list_next(&tx->tx_holds, txh)) {
966		dnode_t *dn = txh->txh_dnode;
967
968		if (dn == NULL)
969			continue;
970		mutex_enter(&dn->dn_mtx);
971		ASSERT3U(dn->dn_assigned_txg, ==, tx->tx_txg);
972
973		if (zfs_refcount_remove(&dn->dn_tx_holds, tx) == 0) {
974			dn->dn_assigned_txg = 0;
975			cv_broadcast(&dn->dn_notxholds);
976		}
977		mutex_exit(&dn->dn_mtx);
978	}
979
980	txg_rele_to_sync(&tx->tx_txgh);
981
982	tx->tx_lasttried_txg = tx->tx_txg;
983	tx->tx_txg = 0;
984}
985
986/*
987 * Assign tx to a transaction group; txg_how is a bitmask:
988 *
989 * If TXG_WAIT is set and the currently open txg is full, this function
990 * will wait until there's a new txg. This should be used when no locks
991 * are being held. With this bit set, this function will only fail if
992 * we're truly out of space (or over quota).
993 *
994 * If TXG_WAIT is *not* set and we can't assign into the currently open
995 * txg without blocking, this function will return immediately with
996 * ERESTART. This should be used whenever locks are being held.  On an
997 * ERESTART error, the caller should drop all locks, call dmu_tx_wait(),
998 * and try again.
999 *
1000 * If TXG_NOTHROTTLE is set, this indicates that this tx should not be
1001 * delayed due on the ZFS Write Throttle (see comments in dsl_pool.c for
1002 * details on the throttle). This is used by the VFS operations, after
1003 * they have already called dmu_tx_wait() (though most likely on a
1004 * different tx).
1005 */
1006int
1007dmu_tx_assign(dmu_tx_t *tx, uint64_t txg_how)
1008{
1009	int err;
1010
1011	ASSERT(tx->tx_txg == 0);
1012	ASSERT0(txg_how & ~(TXG_WAIT | TXG_NOTHROTTLE));
1013	ASSERT(!dsl_pool_sync_context(tx->tx_pool));
1014
1015	/* If we might wait, we must not hold the config lock. */
1016	IMPLY((txg_how & TXG_WAIT), !dsl_pool_config_held(tx->tx_pool));
1017
1018	if ((txg_how & TXG_NOTHROTTLE))
1019		tx->tx_dirty_delayed = B_TRUE;
1020
1021	while ((err = dmu_tx_try_assign(tx, txg_how)) != 0) {
1022		dmu_tx_unassign(tx);
1023
1024		if (err != ERESTART || !(txg_how & TXG_WAIT))
1025			return (err);
1026
1027		dmu_tx_wait(tx);
1028	}
1029
1030	txg_rele_to_quiesce(&tx->tx_txgh);
1031
1032	return (0);
1033}
1034
1035void
1036dmu_tx_wait(dmu_tx_t *tx)
1037{
1038	spa_t *spa = tx->tx_pool->dp_spa;
1039	dsl_pool_t *dp = tx->tx_pool;
1040
1041	ASSERT(tx->tx_txg == 0);
1042	ASSERT(!dsl_pool_config_held(tx->tx_pool));
1043
1044	if (tx->tx_wait_dirty) {
1045		/*
1046		 * dmu_tx_try_assign() has determined that we need to wait
1047		 * because we've consumed much or all of the dirty buffer
1048		 * space.
1049		 */
1050		mutex_enter(&dp->dp_lock);
1051		while (dp->dp_dirty_total >= zfs_dirty_data_max)
1052			cv_wait(&dp->dp_spaceavail_cv, &dp->dp_lock);
1053		uint64_t dirty = dp->dp_dirty_total;
1054		mutex_exit(&dp->dp_lock);
1055
1056		dmu_tx_delay(tx, dirty);
1057
1058		tx->tx_wait_dirty = B_FALSE;
1059
1060		/*
1061		 * Note: setting tx_dirty_delayed only has effect if the
1062		 * caller used TX_WAIT.  Otherwise they are going to
1063		 * destroy this tx and try again.  The common case,
1064		 * zfs_write(), uses TX_WAIT.
1065		 */
1066		tx->tx_dirty_delayed = B_TRUE;
1067	} else if (spa_suspended(spa) || tx->tx_lasttried_txg == 0) {
1068		/*
1069		 * If the pool is suspended we need to wait until it
1070		 * is resumed.  Note that it's possible that the pool
1071		 * has become active after this thread has tried to
1072		 * obtain a tx.  If that's the case then tx_lasttried_txg
1073		 * would not have been set.
1074		 */
1075		txg_wait_synced(dp, spa_last_synced_txg(spa) + 1);
1076	} else if (tx->tx_needassign_txh) {
1077		/*
1078		 * A dnode is assigned to the quiescing txg.  Wait for its
1079		 * transaction to complete.
1080		 */
1081		dnode_t *dn = tx->tx_needassign_txh->txh_dnode;
1082
1083		mutex_enter(&dn->dn_mtx);
1084		while (dn->dn_assigned_txg == tx->tx_lasttried_txg - 1)
1085			cv_wait(&dn->dn_notxholds, &dn->dn_mtx);
1086		mutex_exit(&dn->dn_mtx);
1087		tx->tx_needassign_txh = NULL;
1088	} else {
1089		/*
1090		 * If we have a lot of dirty data just wait until we sync
1091		 * out a TXG at which point we'll hopefully have synced
1092		 * a portion of the changes.
1093		 */
1094		txg_wait_synced(dp, spa_last_synced_txg(spa) + 1);
1095	}
1096}
1097
1098static void
1099dmu_tx_destroy(dmu_tx_t *tx)
1100{
1101	dmu_tx_hold_t *txh;
1102
1103	while ((txh = list_head(&tx->tx_holds)) != NULL) {
1104		dnode_t *dn = txh->txh_dnode;
1105
1106		list_remove(&tx->tx_holds, txh);
1107		zfs_refcount_destroy_many(&txh->txh_space_towrite,
1108		    zfs_refcount_count(&txh->txh_space_towrite));
1109		zfs_refcount_destroy_many(&txh->txh_memory_tohold,
1110		    zfs_refcount_count(&txh->txh_memory_tohold));
1111		kmem_free(txh, sizeof (dmu_tx_hold_t));
1112		if (dn != NULL)
1113			dnode_rele(dn, tx);
1114	}
1115
1116	list_destroy(&tx->tx_callbacks);
1117	list_destroy(&tx->tx_holds);
1118	kmem_free(tx, sizeof (dmu_tx_t));
1119}
1120
1121void
1122dmu_tx_commit(dmu_tx_t *tx)
1123{
1124	ASSERT(tx->tx_txg != 0);
1125
1126	/*
1127	 * Go through the transaction's hold list and remove holds on
1128	 * associated dnodes, notifying waiters if no holds remain.
1129	 */
1130	for (dmu_tx_hold_t *txh = list_head(&tx->tx_holds); txh != NULL;
1131	    txh = list_next(&tx->tx_holds, txh)) {
1132		dnode_t *dn = txh->txh_dnode;
1133
1134		if (dn == NULL)
1135			continue;
1136
1137		mutex_enter(&dn->dn_mtx);
1138		ASSERT3U(dn->dn_assigned_txg, ==, tx->tx_txg);
1139
1140		if (zfs_refcount_remove(&dn->dn_tx_holds, tx) == 0) {
1141			dn->dn_assigned_txg = 0;
1142			cv_broadcast(&dn->dn_notxholds);
1143		}
1144		mutex_exit(&dn->dn_mtx);
1145	}
1146
1147	if (tx->tx_tempreserve_cookie)
1148		dsl_dir_tempreserve_clear(tx->tx_tempreserve_cookie, tx);
1149
1150	if (!list_is_empty(&tx->tx_callbacks))
1151		txg_register_callbacks(&tx->tx_txgh, &tx->tx_callbacks);
1152
1153	if (tx->tx_anyobj == FALSE)
1154		txg_rele_to_sync(&tx->tx_txgh);
1155
1156	dmu_tx_destroy(tx);
1157}
1158
1159void
1160dmu_tx_abort(dmu_tx_t *tx)
1161{
1162	ASSERT(tx->tx_txg == 0);
1163
1164	/*
1165	 * Call any registered callbacks with an error code.
1166	 */
1167	if (!list_is_empty(&tx->tx_callbacks))
1168		dmu_tx_do_callbacks(&tx->tx_callbacks, ECANCELED);
1169
1170	dmu_tx_destroy(tx);
1171}
1172
1173uint64_t
1174dmu_tx_get_txg(dmu_tx_t *tx)
1175{
1176	ASSERT(tx->tx_txg != 0);
1177	return (tx->tx_txg);
1178}
1179
1180dsl_pool_t *
1181dmu_tx_pool(dmu_tx_t *tx)
1182{
1183	ASSERT(tx->tx_pool != NULL);
1184	return (tx->tx_pool);
1185}
1186
1187void
1188dmu_tx_callback_register(dmu_tx_t *tx, dmu_tx_callback_func_t *func, void *data)
1189{
1190	dmu_tx_callback_t *dcb;
1191
1192	dcb = kmem_alloc(sizeof (dmu_tx_callback_t), KM_SLEEP);
1193
1194	dcb->dcb_func = func;
1195	dcb->dcb_data = data;
1196
1197	list_insert_tail(&tx->tx_callbacks, dcb);
1198}
1199
1200/*
1201 * Call all the commit callbacks on a list, with a given error code.
1202 */
1203void
1204dmu_tx_do_callbacks(list_t *cb_list, int error)
1205{
1206	dmu_tx_callback_t *dcb;
1207
1208	while ((dcb = list_head(cb_list)) != NULL) {
1209		list_remove(cb_list, dcb);
1210		dcb->dcb_func(dcb->dcb_data, error);
1211		kmem_free(dcb, sizeof (dmu_tx_callback_t));
1212	}
1213}
1214
1215/*
1216 * Interface to hold a bunch of attributes.
1217 * used for creating new files.
1218 * attrsize is the total size of all attributes
1219 * to be added during object creation
1220 *
1221 * For updating/adding a single attribute dmu_tx_hold_sa() should be used.
1222 */
1223
1224/*
1225 * hold necessary attribute name for attribute registration.
1226 * should be a very rare case where this is needed.  If it does
1227 * happen it would only happen on the first write to the file system.
1228 */
1229static void
1230dmu_tx_sa_registration_hold(sa_os_t *sa, dmu_tx_t *tx)
1231{
1232	if (!sa->sa_need_attr_registration)
1233		return;
1234
1235	for (int i = 0; i != sa->sa_num_attrs; i++) {
1236		if (!sa->sa_attr_table[i].sa_registered) {
1237			if (sa->sa_reg_attr_obj)
1238				dmu_tx_hold_zap(tx, sa->sa_reg_attr_obj,
1239				    B_TRUE, sa->sa_attr_table[i].sa_name);
1240			else
1241				dmu_tx_hold_zap(tx, DMU_NEW_OBJECT,
1242				    B_TRUE, sa->sa_attr_table[i].sa_name);
1243		}
1244	}
1245}
1246
1247void
1248dmu_tx_hold_spill(dmu_tx_t *tx, uint64_t object)
1249{
1250	dmu_tx_hold_t *txh;
1251
1252	txh = dmu_tx_hold_object_impl(tx, tx->tx_objset, object,
1253	    THT_SPILL, 0, 0);
1254	if (txh != NULL)
1255		(void) zfs_refcount_add_many(&txh->txh_space_towrite,
1256		    SPA_OLD_MAXBLOCKSIZE, FTAG);
1257}
1258
1259void
1260dmu_tx_hold_sa_create(dmu_tx_t *tx, int attrsize)
1261{
1262	sa_os_t *sa = tx->tx_objset->os_sa;
1263
1264	dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
1265
1266	if (tx->tx_objset->os_sa->sa_master_obj == 0)
1267		return;
1268
1269	if (tx->tx_objset->os_sa->sa_layout_attr_obj) {
1270		dmu_tx_hold_zap(tx, sa->sa_layout_attr_obj, B_TRUE, NULL);
1271	} else {
1272		dmu_tx_hold_zap(tx, sa->sa_master_obj, B_TRUE, SA_LAYOUTS);
1273		dmu_tx_hold_zap(tx, sa->sa_master_obj, B_TRUE, SA_REGISTRY);
1274		dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, B_TRUE, NULL);
1275		dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, B_TRUE, NULL);
1276	}
1277
1278	dmu_tx_sa_registration_hold(sa, tx);
1279
1280	if (attrsize <= DN_OLD_MAX_BONUSLEN && !sa->sa_force_spill)
1281		return;
1282
1283	(void) dmu_tx_hold_object_impl(tx, tx->tx_objset, DMU_NEW_OBJECT,
1284	    THT_SPILL, 0, 0);
1285}
1286
1287/*
1288 * Hold SA attribute
1289 *
1290 * dmu_tx_hold_sa(dmu_tx_t *tx, sa_handle_t *, attribute, add, size)
1291 *
1292 * variable_size is the total size of all variable sized attributes
1293 * passed to this function.  It is not the total size of all
1294 * variable size attributes that *may* exist on this object.
1295 */
1296void
1297dmu_tx_hold_sa(dmu_tx_t *tx, sa_handle_t *hdl, boolean_t may_grow)
1298{
1299	uint64_t object;
1300	sa_os_t *sa = tx->tx_objset->os_sa;
1301
1302	ASSERT(hdl != NULL);
1303
1304	object = sa_handle_object(hdl);
1305
1306	dmu_tx_hold_bonus(tx, object);
1307
1308	if (tx->tx_objset->os_sa->sa_master_obj == 0)
1309		return;
1310
1311	if (tx->tx_objset->os_sa->sa_reg_attr_obj == 0 ||
1312	    tx->tx_objset->os_sa->sa_layout_attr_obj == 0) {
1313		dmu_tx_hold_zap(tx, sa->sa_master_obj, B_TRUE, SA_LAYOUTS);
1314		dmu_tx_hold_zap(tx, sa->sa_master_obj, B_TRUE, SA_REGISTRY);
1315		dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, B_TRUE, NULL);
1316		dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, B_TRUE, NULL);
1317	}
1318
1319	dmu_tx_sa_registration_hold(sa, tx);
1320
1321	if (may_grow && tx->tx_objset->os_sa->sa_layout_attr_obj)
1322		dmu_tx_hold_zap(tx, sa->sa_layout_attr_obj, B_TRUE, NULL);
1323
1324	if (sa->sa_force_spill || may_grow || hdl->sa_spill) {
1325		ASSERT(tx->tx_txg == 0);
1326		dmu_tx_hold_spill(tx, object);
1327	} else {
1328		dmu_buf_impl_t *db = (dmu_buf_impl_t *)hdl->sa_bonus;
1329		dnode_t *dn;
1330
1331		DB_DNODE_ENTER(db);
1332		dn = DB_DNODE(db);
1333		if (dn->dn_have_spill) {
1334			ASSERT(tx->tx_txg == 0);
1335			dmu_tx_hold_spill(tx, object);
1336		}
1337		DB_DNODE_EXIT(db);
1338	}
1339}
1340