7003 zap_lockdir() should tag hold
[unleashed.git] / usr / src / uts / common / fs / zfs / zap.c
blob674f039fd3113f7086f8877cf02b54d602dfeb1b
1 /*
2 * CDDL HEADER START
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.
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.
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]
19 * CDDL HEADER END
22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright (c) 2012, 2016 by Delphix. All rights reserved.
24 * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
28 * This file contains the top half of the zfs directory structure
29 * implementation. The bottom half is in zap_leaf.c.
31 * The zdir is an extendable hash data structure. There is a table of
32 * pointers to buckets (zap_t->zd_data->zd_leafs). The buckets are
33 * each a constant size and hold a variable number of directory entries.
34 * The buckets (aka "leaf nodes") are implemented in zap_leaf.c.
36 * The pointer table holds a power of 2 number of pointers.
37 * (1<<zap_t->zd_data->zd_phys->zd_prefix_len). The bucket pointed to
38 * by the pointer at index i in the table holds entries whose hash value
39 * has a zd_prefix_len - bit prefix
42 #include <sys/spa.h>
43 #include <sys/dmu.h>
44 #include <sys/zfs_context.h>
45 #include <sys/zfs_znode.h>
46 #include <sys/fs/zfs.h>
47 #include <sys/zap.h>
48 #include <sys/refcount.h>
49 #include <sys/zap_impl.h>
50 #include <sys/zap_leaf.h>
52 int fzap_default_block_shift = 14; /* 16k blocksize */
54 extern inline zap_phys_t *zap_f_phys(zap_t *zap);
56 static uint64_t zap_allocate_blocks(zap_t *zap, int nblocks);
58 void
59 fzap_byteswap(void *vbuf, size_t size)
61 uint64_t block_type;
63 block_type = *(uint64_t *)vbuf;
65 if (block_type == ZBT_LEAF || block_type == BSWAP_64(ZBT_LEAF))
66 zap_leaf_byteswap(vbuf, size);
67 else {
68 /* it's a ptrtbl block */
69 byteswap_uint64_array(vbuf, size);
73 void
74 fzap_upgrade(zap_t *zap, dmu_tx_t *tx, zap_flags_t flags)
76 dmu_buf_t *db;
77 zap_leaf_t *l;
78 int i;
79 zap_phys_t *zp;
81 ASSERT(RW_WRITE_HELD(&zap->zap_rwlock));
82 zap->zap_ismicro = FALSE;
84 zap->zap_dbu.dbu_evict_func = zap_evict;
86 mutex_init(&zap->zap_f.zap_num_entries_mtx, 0, 0, 0);
87 zap->zap_f.zap_block_shift = highbit64(zap->zap_dbuf->db_size) - 1;
89 zp = zap_f_phys(zap);
91 * explicitly zero it since it might be coming from an
92 * initialized microzap
94 bzero(zap->zap_dbuf->db_data, zap->zap_dbuf->db_size);
95 zp->zap_block_type = ZBT_HEADER;
96 zp->zap_magic = ZAP_MAGIC;
98 zp->zap_ptrtbl.zt_shift = ZAP_EMBEDDED_PTRTBL_SHIFT(zap);
100 zp->zap_freeblk = 2; /* block 1 will be the first leaf */
101 zp->zap_num_leafs = 1;
102 zp->zap_num_entries = 0;
103 zp->zap_salt = zap->zap_salt;
104 zp->zap_normflags = zap->zap_normflags;
105 zp->zap_flags = flags;
107 /* block 1 will be the first leaf */
108 for (i = 0; i < (1<<zp->zap_ptrtbl.zt_shift); i++)
109 ZAP_EMBEDDED_PTRTBL_ENT(zap, i) = 1;
112 * set up block 1 - the first leaf
114 VERIFY(0 == dmu_buf_hold(zap->zap_objset, zap->zap_object,
115 1<<FZAP_BLOCK_SHIFT(zap), FTAG, &db, DMU_READ_NO_PREFETCH));
116 dmu_buf_will_dirty(db, tx);
118 l = kmem_zalloc(sizeof (zap_leaf_t), KM_SLEEP);
119 l->l_dbuf = db;
121 zap_leaf_init(l, zp->zap_normflags != 0);
123 kmem_free(l, sizeof (zap_leaf_t));
124 dmu_buf_rele(db, FTAG);
127 static int
128 zap_tryupgradedir(zap_t *zap, dmu_tx_t *tx)
130 if (RW_WRITE_HELD(&zap->zap_rwlock))
131 return (1);
132 if (rw_tryupgrade(&zap->zap_rwlock)) {
133 dmu_buf_will_dirty(zap->zap_dbuf, tx);
134 return (1);
136 return (0);
140 * Generic routines for dealing with the pointer & cookie tables.
143 static int
144 zap_table_grow(zap_t *zap, zap_table_phys_t *tbl,
145 void (*transfer_func)(const uint64_t *src, uint64_t *dst, int n),
146 dmu_tx_t *tx)
148 uint64_t b, newblk;
149 dmu_buf_t *db_old, *db_new;
150 int err;
151 int bs = FZAP_BLOCK_SHIFT(zap);
152 int hepb = 1<<(bs-4);
153 /* hepb = half the number of entries in a block */
155 ASSERT(RW_WRITE_HELD(&zap->zap_rwlock));
156 ASSERT(tbl->zt_blk != 0);
157 ASSERT(tbl->zt_numblks > 0);
159 if (tbl->zt_nextblk != 0) {
160 newblk = tbl->zt_nextblk;
161 } else {
162 newblk = zap_allocate_blocks(zap, tbl->zt_numblks * 2);
163 tbl->zt_nextblk = newblk;
164 ASSERT0(tbl->zt_blks_copied);
165 dmu_prefetch(zap->zap_objset, zap->zap_object, 0,
166 tbl->zt_blk << bs, tbl->zt_numblks << bs,
167 ZIO_PRIORITY_SYNC_READ);
171 * Copy the ptrtbl from the old to new location.
174 b = tbl->zt_blks_copied;
175 err = dmu_buf_hold(zap->zap_objset, zap->zap_object,
176 (tbl->zt_blk + b) << bs, FTAG, &db_old, DMU_READ_NO_PREFETCH);
177 if (err)
178 return (err);
180 /* first half of entries in old[b] go to new[2*b+0] */
181 VERIFY(0 == dmu_buf_hold(zap->zap_objset, zap->zap_object,
182 (newblk + 2*b+0) << bs, FTAG, &db_new, DMU_READ_NO_PREFETCH));
183 dmu_buf_will_dirty(db_new, tx);
184 transfer_func(db_old->db_data, db_new->db_data, hepb);
185 dmu_buf_rele(db_new, FTAG);
187 /* second half of entries in old[b] go to new[2*b+1] */
188 VERIFY(0 == dmu_buf_hold(zap->zap_objset, zap->zap_object,
189 (newblk + 2*b+1) << bs, FTAG, &db_new, DMU_READ_NO_PREFETCH));
190 dmu_buf_will_dirty(db_new, tx);
191 transfer_func((uint64_t *)db_old->db_data + hepb,
192 db_new->db_data, hepb);
193 dmu_buf_rele(db_new, FTAG);
195 dmu_buf_rele(db_old, FTAG);
197 tbl->zt_blks_copied++;
199 dprintf("copied block %llu of %llu\n",
200 tbl->zt_blks_copied, tbl->zt_numblks);
202 if (tbl->zt_blks_copied == tbl->zt_numblks) {
203 (void) dmu_free_range(zap->zap_objset, zap->zap_object,
204 tbl->zt_blk << bs, tbl->zt_numblks << bs, tx);
206 tbl->zt_blk = newblk;
207 tbl->zt_numblks *= 2;
208 tbl->zt_shift++;
209 tbl->zt_nextblk = 0;
210 tbl->zt_blks_copied = 0;
212 dprintf("finished; numblocks now %llu (%lluk entries)\n",
213 tbl->zt_numblks, 1<<(tbl->zt_shift-10));
216 return (0);
219 static int
220 zap_table_store(zap_t *zap, zap_table_phys_t *tbl, uint64_t idx, uint64_t val,
221 dmu_tx_t *tx)
223 int err;
224 uint64_t blk, off;
225 int bs = FZAP_BLOCK_SHIFT(zap);
226 dmu_buf_t *db;
228 ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
229 ASSERT(tbl->zt_blk != 0);
231 dprintf("storing %llx at index %llx\n", val, idx);
233 blk = idx >> (bs-3);
234 off = idx & ((1<<(bs-3))-1);
236 err = dmu_buf_hold(zap->zap_objset, zap->zap_object,
237 (tbl->zt_blk + blk) << bs, FTAG, &db, DMU_READ_NO_PREFETCH);
238 if (err)
239 return (err);
240 dmu_buf_will_dirty(db, tx);
242 if (tbl->zt_nextblk != 0) {
243 uint64_t idx2 = idx * 2;
244 uint64_t blk2 = idx2 >> (bs-3);
245 uint64_t off2 = idx2 & ((1<<(bs-3))-1);
246 dmu_buf_t *db2;
248 err = dmu_buf_hold(zap->zap_objset, zap->zap_object,
249 (tbl->zt_nextblk + blk2) << bs, FTAG, &db2,
250 DMU_READ_NO_PREFETCH);
251 if (err) {
252 dmu_buf_rele(db, FTAG);
253 return (err);
255 dmu_buf_will_dirty(db2, tx);
256 ((uint64_t *)db2->db_data)[off2] = val;
257 ((uint64_t *)db2->db_data)[off2+1] = val;
258 dmu_buf_rele(db2, FTAG);
261 ((uint64_t *)db->db_data)[off] = val;
262 dmu_buf_rele(db, FTAG);
264 return (0);
267 static int
268 zap_table_load(zap_t *zap, zap_table_phys_t *tbl, uint64_t idx, uint64_t *valp)
270 uint64_t blk, off;
271 int err;
272 dmu_buf_t *db;
273 int bs = FZAP_BLOCK_SHIFT(zap);
275 ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
277 blk = idx >> (bs-3);
278 off = idx & ((1<<(bs-3))-1);
280 err = dmu_buf_hold(zap->zap_objset, zap->zap_object,
281 (tbl->zt_blk + blk) << bs, FTAG, &db, DMU_READ_NO_PREFETCH);
282 if (err)
283 return (err);
284 *valp = ((uint64_t *)db->db_data)[off];
285 dmu_buf_rele(db, FTAG);
287 if (tbl->zt_nextblk != 0) {
289 * read the nextblk for the sake of i/o error checking,
290 * so that zap_table_load() will catch errors for
291 * zap_table_store.
293 blk = (idx*2) >> (bs-3);
295 err = dmu_buf_hold(zap->zap_objset, zap->zap_object,
296 (tbl->zt_nextblk + blk) << bs, FTAG, &db,
297 DMU_READ_NO_PREFETCH);
298 if (err == 0)
299 dmu_buf_rele(db, FTAG);
301 return (err);
305 * Routines for growing the ptrtbl.
308 static void
309 zap_ptrtbl_transfer(const uint64_t *src, uint64_t *dst, int n)
311 int i;
312 for (i = 0; i < n; i++) {
313 uint64_t lb = src[i];
314 dst[2*i+0] = lb;
315 dst[2*i+1] = lb;
319 static int
320 zap_grow_ptrtbl(zap_t *zap, dmu_tx_t *tx)
323 * The pointer table should never use more hash bits than we
324 * have (otherwise we'd be using useless zero bits to index it).
325 * If we are within 2 bits of running out, stop growing, since
326 * this is already an aberrant condition.
328 if (zap_f_phys(zap)->zap_ptrtbl.zt_shift >= zap_hashbits(zap) - 2)
329 return (SET_ERROR(ENOSPC));
331 if (zap_f_phys(zap)->zap_ptrtbl.zt_numblks == 0) {
333 * We are outgrowing the "embedded" ptrtbl (the one
334 * stored in the header block). Give it its own entire
335 * block, which will double the size of the ptrtbl.
337 uint64_t newblk;
338 dmu_buf_t *db_new;
339 int err;
341 ASSERT3U(zap_f_phys(zap)->zap_ptrtbl.zt_shift, ==,
342 ZAP_EMBEDDED_PTRTBL_SHIFT(zap));
343 ASSERT0(zap_f_phys(zap)->zap_ptrtbl.zt_blk);
345 newblk = zap_allocate_blocks(zap, 1);
346 err = dmu_buf_hold(zap->zap_objset, zap->zap_object,
347 newblk << FZAP_BLOCK_SHIFT(zap), FTAG, &db_new,
348 DMU_READ_NO_PREFETCH);
349 if (err)
350 return (err);
351 dmu_buf_will_dirty(db_new, tx);
352 zap_ptrtbl_transfer(&ZAP_EMBEDDED_PTRTBL_ENT(zap, 0),
353 db_new->db_data, 1 << ZAP_EMBEDDED_PTRTBL_SHIFT(zap));
354 dmu_buf_rele(db_new, FTAG);
356 zap_f_phys(zap)->zap_ptrtbl.zt_blk = newblk;
357 zap_f_phys(zap)->zap_ptrtbl.zt_numblks = 1;
358 zap_f_phys(zap)->zap_ptrtbl.zt_shift++;
360 ASSERT3U(1ULL << zap_f_phys(zap)->zap_ptrtbl.zt_shift, ==,
361 zap_f_phys(zap)->zap_ptrtbl.zt_numblks <<
362 (FZAP_BLOCK_SHIFT(zap)-3));
364 return (0);
365 } else {
366 return (zap_table_grow(zap, &zap_f_phys(zap)->zap_ptrtbl,
367 zap_ptrtbl_transfer, tx));
371 static void
372 zap_increment_num_entries(zap_t *zap, int delta, dmu_tx_t *tx)
374 dmu_buf_will_dirty(zap->zap_dbuf, tx);
375 mutex_enter(&zap->zap_f.zap_num_entries_mtx);
376 ASSERT(delta > 0 || zap_f_phys(zap)->zap_num_entries >= -delta);
377 zap_f_phys(zap)->zap_num_entries += delta;
378 mutex_exit(&zap->zap_f.zap_num_entries_mtx);
381 static uint64_t
382 zap_allocate_blocks(zap_t *zap, int nblocks)
384 uint64_t newblk;
385 ASSERT(RW_WRITE_HELD(&zap->zap_rwlock));
386 newblk = zap_f_phys(zap)->zap_freeblk;
387 zap_f_phys(zap)->zap_freeblk += nblocks;
388 return (newblk);
391 static void
392 zap_leaf_pageout(void *dbu)
394 zap_leaf_t *l = dbu;
396 rw_destroy(&l->l_rwlock);
397 kmem_free(l, sizeof (zap_leaf_t));
400 static zap_leaf_t *
401 zap_create_leaf(zap_t *zap, dmu_tx_t *tx)
403 void *winner;
404 zap_leaf_t *l = kmem_zalloc(sizeof (zap_leaf_t), KM_SLEEP);
406 ASSERT(RW_WRITE_HELD(&zap->zap_rwlock));
408 rw_init(&l->l_rwlock, 0, 0, 0);
409 rw_enter(&l->l_rwlock, RW_WRITER);
410 l->l_blkid = zap_allocate_blocks(zap, 1);
411 l->l_dbuf = NULL;
413 VERIFY(0 == dmu_buf_hold(zap->zap_objset, zap->zap_object,
414 l->l_blkid << FZAP_BLOCK_SHIFT(zap), NULL, &l->l_dbuf,
415 DMU_READ_NO_PREFETCH));
416 dmu_buf_init_user(&l->l_dbu, zap_leaf_pageout, &l->l_dbuf);
417 winner = dmu_buf_set_user(l->l_dbuf, &l->l_dbu);
418 ASSERT(winner == NULL);
419 dmu_buf_will_dirty(l->l_dbuf, tx);
421 zap_leaf_init(l, zap->zap_normflags != 0);
423 zap_f_phys(zap)->zap_num_leafs++;
425 return (l);
429 fzap_count(zap_t *zap, uint64_t *count)
431 ASSERT(!zap->zap_ismicro);
432 mutex_enter(&zap->zap_f.zap_num_entries_mtx); /* unnecessary */
433 *count = zap_f_phys(zap)->zap_num_entries;
434 mutex_exit(&zap->zap_f.zap_num_entries_mtx);
435 return (0);
439 * Routines for obtaining zap_leaf_t's
442 void
443 zap_put_leaf(zap_leaf_t *l)
445 rw_exit(&l->l_rwlock);
446 dmu_buf_rele(l->l_dbuf, NULL);
449 static zap_leaf_t *
450 zap_open_leaf(uint64_t blkid, dmu_buf_t *db)
452 zap_leaf_t *l, *winner;
454 ASSERT(blkid != 0);
456 l = kmem_zalloc(sizeof (zap_leaf_t), KM_SLEEP);
457 rw_init(&l->l_rwlock, 0, 0, 0);
458 rw_enter(&l->l_rwlock, RW_WRITER);
459 l->l_blkid = blkid;
460 l->l_bs = highbit64(db->db_size) - 1;
461 l->l_dbuf = db;
463 dmu_buf_init_user(&l->l_dbu, zap_leaf_pageout, &l->l_dbuf);
464 winner = dmu_buf_set_user(db, &l->l_dbu);
466 rw_exit(&l->l_rwlock);
467 if (winner != NULL) {
468 /* someone else set it first */
469 zap_leaf_pageout(&l->l_dbu);
470 l = winner;
474 * lhr_pad was previously used for the next leaf in the leaf
475 * chain. There should be no chained leafs (as we have removed
476 * support for them).
478 ASSERT0(zap_leaf_phys(l)->l_hdr.lh_pad1);
481 * There should be more hash entries than there can be
482 * chunks to put in the hash table
484 ASSERT3U(ZAP_LEAF_HASH_NUMENTRIES(l), >, ZAP_LEAF_NUMCHUNKS(l) / 3);
486 /* The chunks should begin at the end of the hash table */
487 ASSERT3P(&ZAP_LEAF_CHUNK(l, 0), ==,
488 &zap_leaf_phys(l)->l_hash[ZAP_LEAF_HASH_NUMENTRIES(l)]);
490 /* The chunks should end at the end of the block */
491 ASSERT3U((uintptr_t)&ZAP_LEAF_CHUNK(l, ZAP_LEAF_NUMCHUNKS(l)) -
492 (uintptr_t)zap_leaf_phys(l), ==, l->l_dbuf->db_size);
494 return (l);
497 static int
498 zap_get_leaf_byblk(zap_t *zap, uint64_t blkid, dmu_tx_t *tx, krw_t lt,
499 zap_leaf_t **lp)
501 dmu_buf_t *db;
502 zap_leaf_t *l;
503 int bs = FZAP_BLOCK_SHIFT(zap);
504 int err;
506 ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
508 err = dmu_buf_hold(zap->zap_objset, zap->zap_object,
509 blkid << bs, NULL, &db, DMU_READ_NO_PREFETCH);
510 if (err)
511 return (err);
513 ASSERT3U(db->db_object, ==, zap->zap_object);
514 ASSERT3U(db->db_offset, ==, blkid << bs);
515 ASSERT3U(db->db_size, ==, 1 << bs);
516 ASSERT(blkid != 0);
518 l = dmu_buf_get_user(db);
520 if (l == NULL)
521 l = zap_open_leaf(blkid, db);
523 rw_enter(&l->l_rwlock, lt);
525 * Must lock before dirtying, otherwise zap_leaf_phys(l) could change,
526 * causing ASSERT below to fail.
528 if (lt == RW_WRITER)
529 dmu_buf_will_dirty(db, tx);
530 ASSERT3U(l->l_blkid, ==, blkid);
531 ASSERT3P(l->l_dbuf, ==, db);
532 ASSERT3U(zap_leaf_phys(l)->l_hdr.lh_block_type, ==, ZBT_LEAF);
533 ASSERT3U(zap_leaf_phys(l)->l_hdr.lh_magic, ==, ZAP_LEAF_MAGIC);
535 *lp = l;
536 return (0);
539 static int
540 zap_idx_to_blk(zap_t *zap, uint64_t idx, uint64_t *valp)
542 ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
544 if (zap_f_phys(zap)->zap_ptrtbl.zt_numblks == 0) {
545 ASSERT3U(idx, <,
546 (1ULL << zap_f_phys(zap)->zap_ptrtbl.zt_shift));
547 *valp = ZAP_EMBEDDED_PTRTBL_ENT(zap, idx);
548 return (0);
549 } else {
550 return (zap_table_load(zap, &zap_f_phys(zap)->zap_ptrtbl,
551 idx, valp));
555 static int
556 zap_set_idx_to_blk(zap_t *zap, uint64_t idx, uint64_t blk, dmu_tx_t *tx)
558 ASSERT(tx != NULL);
559 ASSERT(RW_WRITE_HELD(&zap->zap_rwlock));
561 if (zap_f_phys(zap)->zap_ptrtbl.zt_blk == 0) {
562 ZAP_EMBEDDED_PTRTBL_ENT(zap, idx) = blk;
563 return (0);
564 } else {
565 return (zap_table_store(zap, &zap_f_phys(zap)->zap_ptrtbl,
566 idx, blk, tx));
570 static int
571 zap_deref_leaf(zap_t *zap, uint64_t h, dmu_tx_t *tx, krw_t lt, zap_leaf_t **lp)
573 uint64_t idx, blk;
574 int err;
576 ASSERT(zap->zap_dbuf == NULL ||
577 zap_f_phys(zap) == zap->zap_dbuf->db_data);
579 /* Reality check for corrupt zap objects (leaf or header). */
580 if ((zap_f_phys(zap)->zap_block_type != ZBT_LEAF &&
581 zap_f_phys(zap)->zap_block_type != ZBT_HEADER) ||
582 zap_f_phys(zap)->zap_magic != ZAP_MAGIC) {
583 return (SET_ERROR(EIO));
586 idx = ZAP_HASH_IDX(h, zap_f_phys(zap)->zap_ptrtbl.zt_shift);
587 err = zap_idx_to_blk(zap, idx, &blk);
588 if (err != 0)
589 return (err);
590 err = zap_get_leaf_byblk(zap, blk, tx, lt, lp);
592 ASSERT(err ||
593 ZAP_HASH_IDX(h, zap_leaf_phys(*lp)->l_hdr.lh_prefix_len) ==
594 zap_leaf_phys(*lp)->l_hdr.lh_prefix);
595 return (err);
598 static int
599 zap_expand_leaf(zap_name_t *zn, zap_leaf_t *l,
600 void *tag, dmu_tx_t *tx, zap_leaf_t **lp)
602 zap_t *zap = zn->zn_zap;
603 uint64_t hash = zn->zn_hash;
604 zap_leaf_t *nl;
605 int prefix_diff, i, err;
606 uint64_t sibling;
607 int old_prefix_len = zap_leaf_phys(l)->l_hdr.lh_prefix_len;
609 ASSERT3U(old_prefix_len, <=, zap_f_phys(zap)->zap_ptrtbl.zt_shift);
610 ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
612 ASSERT3U(ZAP_HASH_IDX(hash, old_prefix_len), ==,
613 zap_leaf_phys(l)->l_hdr.lh_prefix);
615 if (zap_tryupgradedir(zap, tx) == 0 ||
616 old_prefix_len == zap_f_phys(zap)->zap_ptrtbl.zt_shift) {
617 /* We failed to upgrade, or need to grow the pointer table */
618 objset_t *os = zap->zap_objset;
619 uint64_t object = zap->zap_object;
621 zap_put_leaf(l);
622 zap_unlockdir(zap, tag);
623 err = zap_lockdir(os, object, tx, RW_WRITER,
624 FALSE, FALSE, tag, &zn->zn_zap);
625 zap = zn->zn_zap;
626 if (err)
627 return (err);
628 ASSERT(!zap->zap_ismicro);
630 while (old_prefix_len ==
631 zap_f_phys(zap)->zap_ptrtbl.zt_shift) {
632 err = zap_grow_ptrtbl(zap, tx);
633 if (err)
634 return (err);
637 err = zap_deref_leaf(zap, hash, tx, RW_WRITER, &l);
638 if (err)
639 return (err);
641 if (zap_leaf_phys(l)->l_hdr.lh_prefix_len != old_prefix_len) {
642 /* it split while our locks were down */
643 *lp = l;
644 return (0);
647 ASSERT(RW_WRITE_HELD(&zap->zap_rwlock));
648 ASSERT3U(old_prefix_len, <, zap_f_phys(zap)->zap_ptrtbl.zt_shift);
649 ASSERT3U(ZAP_HASH_IDX(hash, old_prefix_len), ==,
650 zap_leaf_phys(l)->l_hdr.lh_prefix);
652 prefix_diff = zap_f_phys(zap)->zap_ptrtbl.zt_shift -
653 (old_prefix_len + 1);
654 sibling = (ZAP_HASH_IDX(hash, old_prefix_len + 1) | 1) << prefix_diff;
656 /* check for i/o errors before doing zap_leaf_split */
657 for (i = 0; i < (1ULL<<prefix_diff); i++) {
658 uint64_t blk;
659 err = zap_idx_to_blk(zap, sibling+i, &blk);
660 if (err)
661 return (err);
662 ASSERT3U(blk, ==, l->l_blkid);
665 nl = zap_create_leaf(zap, tx);
666 zap_leaf_split(l, nl, zap->zap_normflags != 0);
668 /* set sibling pointers */
669 for (i = 0; i < (1ULL << prefix_diff); i++) {
670 err = zap_set_idx_to_blk(zap, sibling+i, nl->l_blkid, tx);
671 ASSERT0(err); /* we checked for i/o errors above */
674 if (hash & (1ULL << (64 - zap_leaf_phys(l)->l_hdr.lh_prefix_len))) {
675 /* we want the sibling */
676 zap_put_leaf(l);
677 *lp = nl;
678 } else {
679 zap_put_leaf(nl);
680 *lp = l;
683 return (0);
686 static void
687 zap_put_leaf_maybe_grow_ptrtbl(zap_name_t *zn, zap_leaf_t *l,
688 void *tag, dmu_tx_t *tx)
690 zap_t *zap = zn->zn_zap;
691 int shift = zap_f_phys(zap)->zap_ptrtbl.zt_shift;
692 int leaffull = (zap_leaf_phys(l)->l_hdr.lh_prefix_len == shift &&
693 zap_leaf_phys(l)->l_hdr.lh_nfree < ZAP_LEAF_LOW_WATER);
695 zap_put_leaf(l);
697 if (leaffull || zap_f_phys(zap)->zap_ptrtbl.zt_nextblk) {
698 int err;
701 * We are in the middle of growing the pointer table, or
702 * this leaf will soon make us grow it.
704 if (zap_tryupgradedir(zap, tx) == 0) {
705 objset_t *os = zap->zap_objset;
706 uint64_t zapobj = zap->zap_object;
708 zap_unlockdir(zap, tag);
709 err = zap_lockdir(os, zapobj, tx,
710 RW_WRITER, FALSE, FALSE, tag, &zn->zn_zap);
711 zap = zn->zn_zap;
712 if (err)
713 return;
716 /* could have finished growing while our locks were down */
717 if (zap_f_phys(zap)->zap_ptrtbl.zt_shift == shift)
718 (void) zap_grow_ptrtbl(zap, tx);
722 static int
723 fzap_checkname(zap_name_t *zn)
725 if (zn->zn_key_orig_numints * zn->zn_key_intlen > ZAP_MAXNAMELEN)
726 return (SET_ERROR(ENAMETOOLONG));
727 return (0);
730 static int
731 fzap_checksize(uint64_t integer_size, uint64_t num_integers)
733 /* Only integer sizes supported by C */
734 switch (integer_size) {
735 case 1:
736 case 2:
737 case 4:
738 case 8:
739 break;
740 default:
741 return (SET_ERROR(EINVAL));
744 if (integer_size * num_integers > ZAP_MAXVALUELEN)
745 return (E2BIG);
747 return (0);
750 static int
751 fzap_check(zap_name_t *zn, uint64_t integer_size, uint64_t num_integers)
753 int err;
755 if ((err = fzap_checkname(zn)) != 0)
756 return (err);
757 return (fzap_checksize(integer_size, num_integers));
761 * Routines for manipulating attributes.
764 fzap_lookup(zap_name_t *zn,
765 uint64_t integer_size, uint64_t num_integers, void *buf,
766 char *realname, int rn_len, boolean_t *ncp)
768 zap_leaf_t *l;
769 int err;
770 zap_entry_handle_t zeh;
772 if ((err = fzap_checkname(zn)) != 0)
773 return (err);
775 err = zap_deref_leaf(zn->zn_zap, zn->zn_hash, NULL, RW_READER, &l);
776 if (err != 0)
777 return (err);
778 err = zap_leaf_lookup(l, zn, &zeh);
779 if (err == 0) {
780 if ((err = fzap_checksize(integer_size, num_integers)) != 0) {
781 zap_put_leaf(l);
782 return (err);
785 err = zap_entry_read(&zeh, integer_size, num_integers, buf);
786 (void) zap_entry_read_name(zn->zn_zap, &zeh, rn_len, realname);
787 if (ncp) {
788 *ncp = zap_entry_normalization_conflict(&zeh,
789 zn, NULL, zn->zn_zap);
793 zap_put_leaf(l);
794 return (err);
798 fzap_add_cd(zap_name_t *zn,
799 uint64_t integer_size, uint64_t num_integers,
800 const void *val, uint32_t cd, void *tag, dmu_tx_t *tx)
802 zap_leaf_t *l;
803 int err;
804 zap_entry_handle_t zeh;
805 zap_t *zap = zn->zn_zap;
807 ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
808 ASSERT(!zap->zap_ismicro);
809 ASSERT(fzap_check(zn, integer_size, num_integers) == 0);
811 err = zap_deref_leaf(zap, zn->zn_hash, tx, RW_WRITER, &l);
812 if (err != 0)
813 return (err);
814 retry:
815 err = zap_leaf_lookup(l, zn, &zeh);
816 if (err == 0) {
817 err = SET_ERROR(EEXIST);
818 goto out;
820 if (err != ENOENT)
821 goto out;
823 err = zap_entry_create(l, zn, cd,
824 integer_size, num_integers, val, &zeh);
826 if (err == 0) {
827 zap_increment_num_entries(zap, 1, tx);
828 } else if (err == EAGAIN) {
829 err = zap_expand_leaf(zn, l, tag, tx, &l);
830 zap = zn->zn_zap; /* zap_expand_leaf() may change zap */
831 if (err == 0)
832 goto retry;
835 out:
836 if (zap != NULL)
837 zap_put_leaf_maybe_grow_ptrtbl(zn, l, tag, tx);
838 return (err);
842 fzap_add(zap_name_t *zn,
843 uint64_t integer_size, uint64_t num_integers,
844 const void *val, void *tag, dmu_tx_t *tx)
846 int err = fzap_check(zn, integer_size, num_integers);
847 if (err != 0)
848 return (err);
850 return (fzap_add_cd(zn, integer_size, num_integers,
851 val, ZAP_NEED_CD, tag, tx));
855 fzap_update(zap_name_t *zn,
856 int integer_size, uint64_t num_integers, const void *val,
857 void *tag, dmu_tx_t *tx)
859 zap_leaf_t *l;
860 int err, create;
861 zap_entry_handle_t zeh;
862 zap_t *zap = zn->zn_zap;
864 ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
865 err = fzap_check(zn, integer_size, num_integers);
866 if (err != 0)
867 return (err);
869 err = zap_deref_leaf(zap, zn->zn_hash, tx, RW_WRITER, &l);
870 if (err != 0)
871 return (err);
872 retry:
873 err = zap_leaf_lookup(l, zn, &zeh);
874 create = (err == ENOENT);
875 ASSERT(err == 0 || err == ENOENT);
877 if (create) {
878 err = zap_entry_create(l, zn, ZAP_NEED_CD,
879 integer_size, num_integers, val, &zeh);
880 if (err == 0)
881 zap_increment_num_entries(zap, 1, tx);
882 } else {
883 err = zap_entry_update(&zeh, integer_size, num_integers, val);
886 if (err == EAGAIN) {
887 err = zap_expand_leaf(zn, l, tag, tx, &l);
888 zap = zn->zn_zap; /* zap_expand_leaf() may change zap */
889 if (err == 0)
890 goto retry;
893 if (zap != NULL)
894 zap_put_leaf_maybe_grow_ptrtbl(zn, l, tag, tx);
895 return (err);
899 fzap_length(zap_name_t *zn,
900 uint64_t *integer_size, uint64_t *num_integers)
902 zap_leaf_t *l;
903 int err;
904 zap_entry_handle_t zeh;
906 err = zap_deref_leaf(zn->zn_zap, zn->zn_hash, NULL, RW_READER, &l);
907 if (err != 0)
908 return (err);
909 err = zap_leaf_lookup(l, zn, &zeh);
910 if (err != 0)
911 goto out;
913 if (integer_size)
914 *integer_size = zeh.zeh_integer_size;
915 if (num_integers)
916 *num_integers = zeh.zeh_num_integers;
917 out:
918 zap_put_leaf(l);
919 return (err);
923 fzap_remove(zap_name_t *zn, dmu_tx_t *tx)
925 zap_leaf_t *l;
926 int err;
927 zap_entry_handle_t zeh;
929 err = zap_deref_leaf(zn->zn_zap, zn->zn_hash, tx, RW_WRITER, &l);
930 if (err != 0)
931 return (err);
932 err = zap_leaf_lookup(l, zn, &zeh);
933 if (err == 0) {
934 zap_entry_remove(&zeh);
935 zap_increment_num_entries(zn->zn_zap, -1, tx);
937 zap_put_leaf(l);
938 return (err);
941 void
942 fzap_prefetch(zap_name_t *zn)
944 uint64_t idx, blk;
945 zap_t *zap = zn->zn_zap;
946 int bs;
948 idx = ZAP_HASH_IDX(zn->zn_hash,
949 zap_f_phys(zap)->zap_ptrtbl.zt_shift);
950 if (zap_idx_to_blk(zap, idx, &blk) != 0)
951 return;
952 bs = FZAP_BLOCK_SHIFT(zap);
953 dmu_prefetch(zap->zap_objset, zap->zap_object, 0, blk << bs, 1 << bs,
954 ZIO_PRIORITY_SYNC_READ);
958 * Helper functions for consumers.
961 uint64_t
962 zap_create_link(objset_t *os, dmu_object_type_t ot, uint64_t parent_obj,
963 const char *name, dmu_tx_t *tx)
965 uint64_t new_obj;
967 VERIFY((new_obj = zap_create(os, ot, DMU_OT_NONE, 0, tx)) > 0);
968 VERIFY0(zap_add(os, parent_obj, name, sizeof (uint64_t), 1, &new_obj,
969 tx));
971 return (new_obj);
975 zap_value_search(objset_t *os, uint64_t zapobj, uint64_t value, uint64_t mask,
976 char *name)
978 zap_cursor_t zc;
979 zap_attribute_t *za;
980 int err;
982 if (mask == 0)
983 mask = -1ULL;
985 za = kmem_alloc(sizeof (zap_attribute_t), KM_SLEEP);
986 for (zap_cursor_init(&zc, os, zapobj);
987 (err = zap_cursor_retrieve(&zc, za)) == 0;
988 zap_cursor_advance(&zc)) {
989 if ((za->za_first_integer & mask) == (value & mask)) {
990 (void) strcpy(name, za->za_name);
991 break;
994 zap_cursor_fini(&zc);
995 kmem_free(za, sizeof (zap_attribute_t));
996 return (err);
1000 zap_join(objset_t *os, uint64_t fromobj, uint64_t intoobj, dmu_tx_t *tx)
1002 zap_cursor_t zc;
1003 zap_attribute_t za;
1004 int err;
1006 err = 0;
1007 for (zap_cursor_init(&zc, os, fromobj);
1008 zap_cursor_retrieve(&zc, &za) == 0;
1009 (void) zap_cursor_advance(&zc)) {
1010 if (za.za_integer_length != 8 || za.za_num_integers != 1) {
1011 err = SET_ERROR(EINVAL);
1012 break;
1014 err = zap_add(os, intoobj, za.za_name,
1015 8, 1, &za.za_first_integer, tx);
1016 if (err)
1017 break;
1019 zap_cursor_fini(&zc);
1020 return (err);
1024 zap_join_key(objset_t *os, uint64_t fromobj, uint64_t intoobj,
1025 uint64_t value, dmu_tx_t *tx)
1027 zap_cursor_t zc;
1028 zap_attribute_t za;
1029 int err;
1031 err = 0;
1032 for (zap_cursor_init(&zc, os, fromobj);
1033 zap_cursor_retrieve(&zc, &za) == 0;
1034 (void) zap_cursor_advance(&zc)) {
1035 if (za.za_integer_length != 8 || za.za_num_integers != 1) {
1036 err = SET_ERROR(EINVAL);
1037 break;
1039 err = zap_add(os, intoobj, za.za_name,
1040 8, 1, &value, tx);
1041 if (err)
1042 break;
1044 zap_cursor_fini(&zc);
1045 return (err);
1049 zap_join_increment(objset_t *os, uint64_t fromobj, uint64_t intoobj,
1050 dmu_tx_t *tx)
1052 zap_cursor_t zc;
1053 zap_attribute_t za;
1054 int err;
1056 err = 0;
1057 for (zap_cursor_init(&zc, os, fromobj);
1058 zap_cursor_retrieve(&zc, &za) == 0;
1059 (void) zap_cursor_advance(&zc)) {
1060 uint64_t delta = 0;
1062 if (za.za_integer_length != 8 || za.za_num_integers != 1) {
1063 err = SET_ERROR(EINVAL);
1064 break;
1067 err = zap_lookup(os, intoobj, za.za_name, 8, 1, &delta);
1068 if (err != 0 && err != ENOENT)
1069 break;
1070 delta += za.za_first_integer;
1071 err = zap_update(os, intoobj, za.za_name, 8, 1, &delta, tx);
1072 if (err)
1073 break;
1075 zap_cursor_fini(&zc);
1076 return (err);
1080 zap_add_int(objset_t *os, uint64_t obj, uint64_t value, dmu_tx_t *tx)
1082 char name[20];
1084 (void) snprintf(name, sizeof (name), "%llx", (longlong_t)value);
1085 return (zap_add(os, obj, name, 8, 1, &value, tx));
1089 zap_remove_int(objset_t *os, uint64_t obj, uint64_t value, dmu_tx_t *tx)
1091 char name[20];
1093 (void) snprintf(name, sizeof (name), "%llx", (longlong_t)value);
1094 return (zap_remove(os, obj, name, tx));
1098 zap_lookup_int(objset_t *os, uint64_t obj, uint64_t value)
1100 char name[20];
1102 (void) snprintf(name, sizeof (name), "%llx", (longlong_t)value);
1103 return (zap_lookup(os, obj, name, 8, 1, &value));
1107 zap_add_int_key(objset_t *os, uint64_t obj,
1108 uint64_t key, uint64_t value, dmu_tx_t *tx)
1110 char name[20];
1112 (void) snprintf(name, sizeof (name), "%llx", (longlong_t)key);
1113 return (zap_add(os, obj, name, 8, 1, &value, tx));
1117 zap_update_int_key(objset_t *os, uint64_t obj,
1118 uint64_t key, uint64_t value, dmu_tx_t *tx)
1120 char name[20];
1122 (void) snprintf(name, sizeof (name), "%llx", (longlong_t)key);
1123 return (zap_update(os, obj, name, 8, 1, &value, tx));
1127 zap_lookup_int_key(objset_t *os, uint64_t obj, uint64_t key, uint64_t *valuep)
1129 char name[20];
1131 (void) snprintf(name, sizeof (name), "%llx", (longlong_t)key);
1132 return (zap_lookup(os, obj, name, 8, 1, valuep));
1136 zap_increment(objset_t *os, uint64_t obj, const char *name, int64_t delta,
1137 dmu_tx_t *tx)
1139 uint64_t value = 0;
1140 int err;
1142 if (delta == 0)
1143 return (0);
1145 err = zap_lookup(os, obj, name, 8, 1, &value);
1146 if (err != 0 && err != ENOENT)
1147 return (err);
1148 value += delta;
1149 if (value == 0)
1150 err = zap_remove(os, obj, name, tx);
1151 else
1152 err = zap_update(os, obj, name, 8, 1, &value, tx);
1153 return (err);
1157 zap_increment_int(objset_t *os, uint64_t obj, uint64_t key, int64_t delta,
1158 dmu_tx_t *tx)
1160 char name[20];
1162 (void) snprintf(name, sizeof (name), "%llx", (longlong_t)key);
1163 return (zap_increment(os, obj, name, delta, tx));
1167 * Routines for iterating over the attributes.
1171 fzap_cursor_retrieve(zap_t *zap, zap_cursor_t *zc, zap_attribute_t *za)
1173 int err = ENOENT;
1174 zap_entry_handle_t zeh;
1175 zap_leaf_t *l;
1177 /* retrieve the next entry at or after zc_hash/zc_cd */
1178 /* if no entry, return ENOENT */
1180 if (zc->zc_leaf &&
1181 (ZAP_HASH_IDX(zc->zc_hash,
1182 zap_leaf_phys(zc->zc_leaf)->l_hdr.lh_prefix_len) !=
1183 zap_leaf_phys(zc->zc_leaf)->l_hdr.lh_prefix)) {
1184 rw_enter(&zc->zc_leaf->l_rwlock, RW_READER);
1185 zap_put_leaf(zc->zc_leaf);
1186 zc->zc_leaf = NULL;
1189 again:
1190 if (zc->zc_leaf == NULL) {
1191 err = zap_deref_leaf(zap, zc->zc_hash, NULL, RW_READER,
1192 &zc->zc_leaf);
1193 if (err != 0)
1194 return (err);
1195 } else {
1196 rw_enter(&zc->zc_leaf->l_rwlock, RW_READER);
1198 l = zc->zc_leaf;
1200 err = zap_leaf_lookup_closest(l, zc->zc_hash, zc->zc_cd, &zeh);
1202 if (err == ENOENT) {
1203 uint64_t nocare =
1204 (1ULL << (64 - zap_leaf_phys(l)->l_hdr.lh_prefix_len)) - 1;
1205 zc->zc_hash = (zc->zc_hash & ~nocare) + nocare + 1;
1206 zc->zc_cd = 0;
1207 if (zap_leaf_phys(l)->l_hdr.lh_prefix_len == 0 ||
1208 zc->zc_hash == 0) {
1209 zc->zc_hash = -1ULL;
1210 } else {
1211 zap_put_leaf(zc->zc_leaf);
1212 zc->zc_leaf = NULL;
1213 goto again;
1217 if (err == 0) {
1218 zc->zc_hash = zeh.zeh_hash;
1219 zc->zc_cd = zeh.zeh_cd;
1220 za->za_integer_length = zeh.zeh_integer_size;
1221 za->za_num_integers = zeh.zeh_num_integers;
1222 if (zeh.zeh_num_integers == 0) {
1223 za->za_first_integer = 0;
1224 } else {
1225 err = zap_entry_read(&zeh, 8, 1, &za->za_first_integer);
1226 ASSERT(err == 0 || err == EOVERFLOW);
1228 err = zap_entry_read_name(zap, &zeh,
1229 sizeof (za->za_name), za->za_name);
1230 ASSERT(err == 0);
1232 za->za_normalization_conflict =
1233 zap_entry_normalization_conflict(&zeh,
1234 NULL, za->za_name, zap);
1236 rw_exit(&zc->zc_leaf->l_rwlock);
1237 return (err);
1240 static void
1241 zap_stats_ptrtbl(zap_t *zap, uint64_t *tbl, int len, zap_stats_t *zs)
1243 int i, err;
1244 uint64_t lastblk = 0;
1247 * NB: if a leaf has more pointers than an entire ptrtbl block
1248 * can hold, then it'll be accounted for more than once, since
1249 * we won't have lastblk.
1251 for (i = 0; i < len; i++) {
1252 zap_leaf_t *l;
1254 if (tbl[i] == lastblk)
1255 continue;
1256 lastblk = tbl[i];
1258 err = zap_get_leaf_byblk(zap, tbl[i], NULL, RW_READER, &l);
1259 if (err == 0) {
1260 zap_leaf_stats(zap, l, zs);
1261 zap_put_leaf(l);
1266 void
1267 fzap_get_stats(zap_t *zap, zap_stats_t *zs)
1269 int bs = FZAP_BLOCK_SHIFT(zap);
1270 zs->zs_blocksize = 1ULL << bs;
1273 * Set zap_phys_t fields
1275 zs->zs_num_leafs = zap_f_phys(zap)->zap_num_leafs;
1276 zs->zs_num_entries = zap_f_phys(zap)->zap_num_entries;
1277 zs->zs_num_blocks = zap_f_phys(zap)->zap_freeblk;
1278 zs->zs_block_type = zap_f_phys(zap)->zap_block_type;
1279 zs->zs_magic = zap_f_phys(zap)->zap_magic;
1280 zs->zs_salt = zap_f_phys(zap)->zap_salt;
1283 * Set zap_ptrtbl fields
1285 zs->zs_ptrtbl_len = 1ULL << zap_f_phys(zap)->zap_ptrtbl.zt_shift;
1286 zs->zs_ptrtbl_nextblk = zap_f_phys(zap)->zap_ptrtbl.zt_nextblk;
1287 zs->zs_ptrtbl_blks_copied =
1288 zap_f_phys(zap)->zap_ptrtbl.zt_blks_copied;
1289 zs->zs_ptrtbl_zt_blk = zap_f_phys(zap)->zap_ptrtbl.zt_blk;
1290 zs->zs_ptrtbl_zt_numblks = zap_f_phys(zap)->zap_ptrtbl.zt_numblks;
1291 zs->zs_ptrtbl_zt_shift = zap_f_phys(zap)->zap_ptrtbl.zt_shift;
1293 if (zap_f_phys(zap)->zap_ptrtbl.zt_numblks == 0) {
1294 /* the ptrtbl is entirely in the header block. */
1295 zap_stats_ptrtbl(zap, &ZAP_EMBEDDED_PTRTBL_ENT(zap, 0),
1296 1 << ZAP_EMBEDDED_PTRTBL_SHIFT(zap), zs);
1297 } else {
1298 int b;
1300 dmu_prefetch(zap->zap_objset, zap->zap_object, 0,
1301 zap_f_phys(zap)->zap_ptrtbl.zt_blk << bs,
1302 zap_f_phys(zap)->zap_ptrtbl.zt_numblks << bs,
1303 ZIO_PRIORITY_SYNC_READ);
1305 for (b = 0; b < zap_f_phys(zap)->zap_ptrtbl.zt_numblks;
1306 b++) {
1307 dmu_buf_t *db;
1308 int err;
1310 err = dmu_buf_hold(zap->zap_objset, zap->zap_object,
1311 (zap_f_phys(zap)->zap_ptrtbl.zt_blk + b) << bs,
1312 FTAG, &db, DMU_READ_NO_PREFETCH);
1313 if (err == 0) {
1314 zap_stats_ptrtbl(zap, db->db_data,
1315 1<<(bs-3), zs);
1316 dmu_buf_rele(db, FTAG);
1323 fzap_count_write(zap_name_t *zn, int add, refcount_t *towrite,
1324 refcount_t *tooverwrite)
1326 zap_t *zap = zn->zn_zap;
1327 zap_leaf_t *l;
1328 int err;
1331 * Account for the header block of the fatzap.
1333 if (!add && dmu_buf_freeable(zap->zap_dbuf)) {
1334 (void) refcount_add_many(tooverwrite,
1335 zap->zap_dbuf->db_size, FTAG);
1336 } else {
1337 (void) refcount_add_many(towrite,
1338 zap->zap_dbuf->db_size, FTAG);
1342 * Account for the pointer table blocks.
1343 * If we are adding we need to account for the following cases :
1344 * - If the pointer table is embedded, this operation could force an
1345 * external pointer table.
1346 * - If this already has an external pointer table this operation
1347 * could extend the table.
1349 if (add) {
1350 if (zap_f_phys(zap)->zap_ptrtbl.zt_blk == 0) {
1351 (void) refcount_add_many(towrite,
1352 zap->zap_dbuf->db_size, FTAG);
1353 } else {
1354 (void) refcount_add_many(towrite,
1355 zap->zap_dbuf->db_size * 3, FTAG);
1360 * Now, check if the block containing leaf is freeable
1361 * and account accordingly.
1363 err = zap_deref_leaf(zap, zn->zn_hash, NULL, RW_READER, &l);
1364 if (err != 0) {
1365 return (err);
1368 if (!add && dmu_buf_freeable(l->l_dbuf)) {
1369 (void) refcount_add_many(tooverwrite, l->l_dbuf->db_size, FTAG);
1370 } else {
1372 * If this an add operation, the leaf block could split.
1373 * Hence, we need to account for an additional leaf block.
1375 (void) refcount_add_many(towrite,
1376 (add ? 2 : 1) * l->l_dbuf->db_size, FTAG);
1379 zap_put_leaf(l);
1380 return (0);