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