1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  23  * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
  24  * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
  25  */
  26 
  27 /*
  28  * This file contains the top half of the zfs directory structure
  29  * implementation. The bottom half is in zap_leaf.c.
  30  *
  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.
  35  *
  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
  40  */
  41 
  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>
  51 
  52 int fzap_default_block_shift = 14; /* 16k blocksize */
  53 
  54 extern inline zap_phys_t *zap_f_phys(zap_t *zap);
  55 
  56 static uint64_t zap_allocate_blocks(zap_t *zap, int nblocks);
  57 
  58 void
  59 fzap_byteswap(void *vbuf, size_t size)
  60 {
  61         uint64_t block_type;
  62 
  63         block_type = *(uint64_t *)vbuf;
  64 
  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);
  70         }
  71 }
  72 
  73 void
  74 fzap_upgrade(zap_t *zap, dmu_tx_t *tx, zap_flags_t flags)
  75 {
  76         dmu_buf_t *db;
  77         zap_leaf_t *l;
  78         int i;
  79         zap_phys_t *zp;
  80 
  81         ASSERT(RW_WRITE_HELD(&zap->zap_rwlock));
  82         zap->zap_ismicro = FALSE;
  83 
  84         zap->zap_dbu.dbu_evict_func = zap_evict;
  85 
  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;
  88 
  89         zp = zap_f_phys(zap);
  90         /*
  91          * explicitly zero it since it might be coming from an
  92          * initialized microzap
  93          */
  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;
  97 
  98         zp->zap_ptrtbl.zt_shift = ZAP_EMBEDDED_PTRTBL_SHIFT(zap);
  99 
 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;
 106 
 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;
 110 
 111         /*
 112          * set up block 1 - the first leaf
 113          */
 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);
 117 
 118         l = kmem_zalloc(sizeof (zap_leaf_t), KM_SLEEP);
 119         l->l_dbuf = db;
 120 
 121         zap_leaf_init(l, zp->zap_normflags != 0);
 122 
 123         kmem_free(l, sizeof (zap_leaf_t));
 124         dmu_buf_rele(db, FTAG);
 125 }
 126 
 127 static int
 128 zap_tryupgradedir(zap_t *zap, dmu_tx_t *tx)
 129 {
 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);
 135         }
 136         return (0);
 137 }
 138 
 139 /*
 140  * Generic routines for dealing with the pointer & cookie tables.
 141  */
 142 
 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)
 147 {
 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 */
 154 
 155         ASSERT(RW_WRITE_HELD(&zap->zap_rwlock));
 156         ASSERT(tbl->zt_blk != 0);
 157         ASSERT(tbl->zt_numblks > 0);
 158 
 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);
 168         }
 169 
 170         /*
 171          * Copy the ptrtbl from the old to new location.
 172          */
 173 
 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);
 179 
 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);
 186 
 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);
 194 
 195         dmu_buf_rele(db_old, FTAG);
 196 
 197         tbl->zt_blks_copied++;
 198 
 199         dprintf("copied block %llu of %llu\n",
 200             tbl->zt_blks_copied, tbl->zt_numblks);
 201 
 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);
 205 
 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;
 211 
 212                 dprintf("finished; numblocks now %llu (%lluk entries)\n",
 213                     tbl->zt_numblks, 1<<(tbl->zt_shift-10));
 214         }
 215 
 216         return (0);
 217 }
 218 
 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)
 222 {
 223         int err;
 224         uint64_t blk, off;
 225         int bs = FZAP_BLOCK_SHIFT(zap);
 226         dmu_buf_t *db;
 227 
 228         ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
 229         ASSERT(tbl->zt_blk != 0);
 230 
 231         dprintf("storing %llx at index %llx\n", val, idx);
 232 
 233         blk = idx >> (bs-3);
 234         off = idx & ((1<<(bs-3))-1);
 235 
 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);
 241 
 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;
 247 
 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);
 254                 }
 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);
 259         }
 260 
 261         ((uint64_t *)db->db_data)[off] = val;
 262         dmu_buf_rele(db, FTAG);
 263 
 264         return (0);
 265 }
 266 
 267 static int
 268 zap_table_load(zap_t *zap, zap_table_phys_t *tbl, uint64_t idx, uint64_t *valp)
 269 {
 270         uint64_t blk, off;
 271         int err;
 272         dmu_buf_t *db;
 273         int bs = FZAP_BLOCK_SHIFT(zap);
 274 
 275         ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
 276 
 277         blk = idx >> (bs-3);
 278         off = idx & ((1<<(bs-3))-1);
 279 
 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);
 286 
 287         if (tbl->zt_nextblk != 0) {
 288                 /*
 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.
 292                  */
 293                 blk = (idx*2) >> (bs-3);
 294 
 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);
 300         }
 301         return (err);
 302 }
 303 
 304 /*
 305  * Routines for growing the ptrtbl.
 306  */
 307 
 308 static void
 309 zap_ptrtbl_transfer(const uint64_t *src, uint64_t *dst, int n)
 310 {
 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;
 316         }
 317 }
 318 
 319 static int
 320 zap_grow_ptrtbl(zap_t *zap, dmu_tx_t *tx)
 321 {
 322         /*
 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.
 327          */
 328         if (zap_f_phys(zap)->zap_ptrtbl.zt_shift >= zap_hashbits(zap) - 2)
 329                 return (SET_ERROR(ENOSPC));
 330 
 331         if (zap_f_phys(zap)->zap_ptrtbl.zt_numblks == 0) {
 332                 /*
 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.
 336                  */
 337                 uint64_t newblk;
 338                 dmu_buf_t *db_new;
 339                 int err;
 340 
 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);
 344 
 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);
 355 
 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++;
 359 
 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));
 363 
 364                 return (0);
 365         } else {
 366                 return (zap_table_grow(zap, &zap_f_phys(zap)->zap_ptrtbl,
 367                     zap_ptrtbl_transfer, tx));
 368         }
 369 }
 370 
 371 static void
 372 zap_increment_num_entries(zap_t *zap, int delta, dmu_tx_t *tx)
 373 {
 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);
 379 }
 380 
 381 static uint64_t
 382 zap_allocate_blocks(zap_t *zap, int nblocks)
 383 {
 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);
 389 }
 390 
 391 static void
 392 zap_leaf_pageout(void *dbu)
 393 {
 394         zap_leaf_t *l = dbu;
 395 
 396         rw_destroy(&l->l_rwlock);
 397         kmem_free(l, sizeof (zap_leaf_t));
 398 }
 399 
 400 static zap_leaf_t *
 401 zap_create_leaf(zap_t *zap, dmu_tx_t *tx)
 402 {
 403         void *winner;
 404         zap_leaf_t *l = kmem_zalloc(sizeof (zap_leaf_t), KM_SLEEP);
 405 
 406         ASSERT(RW_WRITE_HELD(&zap->zap_rwlock));
 407 
 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;
 412 
 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);
 420 
 421         zap_leaf_init(l, zap->zap_normflags != 0);
 422 
 423         zap_f_phys(zap)->zap_num_leafs++;
 424 
 425         return (l);
 426 }
 427 
 428 int
 429 fzap_count(zap_t *zap, uint64_t *count)
 430 {
 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);
 436 }
 437 
 438 /*
 439  * Routines for obtaining zap_leaf_t's
 440  */
 441 
 442 void
 443 zap_put_leaf(zap_leaf_t *l)
 444 {
 445         rw_exit(&l->l_rwlock);
 446         dmu_buf_rele(l->l_dbuf, NULL);
 447 }
 448 
 449 static zap_leaf_t *
 450 zap_open_leaf(uint64_t blkid, dmu_buf_t *db)
 451 {
 452         zap_leaf_t *l, *winner;
 453 
 454         ASSERT(blkid != 0);
 455 
 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;
 462 
 463         dmu_buf_init_user(&l->l_dbu, zap_leaf_pageout, &l->l_dbuf);
 464         winner = dmu_buf_set_user(db, &l->l_dbu);
 465 
 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;
 471         }
 472 
 473         /*
 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).
 477          */
 478         ASSERT0(zap_leaf_phys(l)->l_hdr.lh_pad1);
 479 
 480         /*
 481          * There should be more hash entries than there can be
 482          * chunks to put in the hash table
 483          */
 484         ASSERT3U(ZAP_LEAF_HASH_NUMENTRIES(l), >, ZAP_LEAF_NUMCHUNKS(l) / 3);
 485 
 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)]);
 489 
 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);
 493 
 494         return (l);
 495 }
 496 
 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)
 500 {
 501         dmu_buf_t *db;
 502         zap_leaf_t *l;
 503         int bs = FZAP_BLOCK_SHIFT(zap);
 504         int err;
 505 
 506         ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
 507 
 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);
 512 
 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);
 517 
 518         l = dmu_buf_get_user(db);
 519 
 520         if (l == NULL)
 521                 l = zap_open_leaf(blkid, db);
 522 
 523         rw_enter(&l->l_rwlock, lt);
 524         /*
 525          * Must lock before dirtying, otherwise zap_leaf_phys(l) could change,
 526          * causing ASSERT below to fail.
 527          */
 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);
 534 
 535         *lp = l;
 536         return (0);
 537 }
 538 
 539 static int
 540 zap_idx_to_blk(zap_t *zap, uint64_t idx, uint64_t *valp)
 541 {
 542         ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
 543 
 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));
 552         }
 553 }
 554 
 555 static int
 556 zap_set_idx_to_blk(zap_t *zap, uint64_t idx, uint64_t blk, dmu_tx_t *tx)
 557 {
 558         ASSERT(tx != NULL);
 559         ASSERT(RW_WRITE_HELD(&zap->zap_rwlock));
 560 
 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));
 567         }
 568 }
 569 
 570 static int
 571 zap_deref_leaf(zap_t *zap, uint64_t h, dmu_tx_t *tx, krw_t lt, zap_leaf_t **lp)
 572 {
 573         uint64_t idx, blk;
 574         int err;
 575 
 576         ASSERT(zap->zap_dbuf == NULL ||
 577             zap_f_phys(zap) == zap->zap_dbuf->db_data);
 578 
 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));
 584         }
 585 
 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);
 591 
 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);
 596 }
 597 
 598 static int
 599 zap_expand_leaf(zap_name_t *zn, zap_leaf_t *l, dmu_tx_t *tx, zap_leaf_t **lp)
 600 {
 601         zap_t *zap = zn->zn_zap;
 602         uint64_t hash = zn->zn_hash;
 603         zap_leaf_t *nl;
 604         int prefix_diff, i, err;
 605         uint64_t sibling;
 606         int old_prefix_len = zap_leaf_phys(l)->l_hdr.lh_prefix_len;
 607 
 608         ASSERT3U(old_prefix_len, <=, zap_f_phys(zap)->zap_ptrtbl.zt_shift);
 609         ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
 610 
 611         ASSERT3U(ZAP_HASH_IDX(hash, old_prefix_len), ==,
 612             zap_leaf_phys(l)->l_hdr.lh_prefix);
 613 
 614         if (zap_tryupgradedir(zap, tx) == 0 ||
 615             old_prefix_len == zap_f_phys(zap)->zap_ptrtbl.zt_shift) {
 616                 /* We failed to upgrade, or need to grow the pointer table */
 617                 objset_t *os = zap->zap_objset;
 618                 uint64_t object = zap->zap_object;
 619 
 620                 zap_put_leaf(l);
 621                 zap_unlockdir(zap);
 622                 err = zap_lockdir(os, object, tx, RW_WRITER,
 623                     FALSE, FALSE, &zn->zn_zap);
 624                 zap = zn->zn_zap;
 625                 if (err)
 626                         return (err);
 627                 ASSERT(!zap->zap_ismicro);
 628 
 629                 while (old_prefix_len ==
 630                     zap_f_phys(zap)->zap_ptrtbl.zt_shift) {
 631                         err = zap_grow_ptrtbl(zap, tx);
 632                         if (err)
 633                                 return (err);
 634                 }
 635 
 636                 err = zap_deref_leaf(zap, hash, tx, RW_WRITER, &l);
 637                 if (err)
 638                         return (err);
 639 
 640                 if (zap_leaf_phys(l)->l_hdr.lh_prefix_len != old_prefix_len) {
 641                         /* it split while our locks were down */
 642                         *lp = l;
 643                         return (0);
 644                 }
 645         }
 646         ASSERT(RW_WRITE_HELD(&zap->zap_rwlock));
 647         ASSERT3U(old_prefix_len, <, zap_f_phys(zap)->zap_ptrtbl.zt_shift);
 648         ASSERT3U(ZAP_HASH_IDX(hash, old_prefix_len), ==,
 649             zap_leaf_phys(l)->l_hdr.lh_prefix);
 650 
 651         prefix_diff = zap_f_phys(zap)->zap_ptrtbl.zt_shift -
 652             (old_prefix_len + 1);
 653         sibling = (ZAP_HASH_IDX(hash, old_prefix_len + 1) | 1) << prefix_diff;
 654 
 655         /* check for i/o errors before doing zap_leaf_split */
 656         for (i = 0; i < (1ULL<<prefix_diff); i++) {
 657                 uint64_t blk;
 658                 err = zap_idx_to_blk(zap, sibling+i, &blk);
 659                 if (err)
 660                         return (err);
 661                 ASSERT3U(blk, ==, l->l_blkid);
 662         }
 663 
 664         nl = zap_create_leaf(zap, tx);
 665         zap_leaf_split(l, nl, zap->zap_normflags != 0);
 666 
 667         /* set sibling pointers */
 668         for (i = 0; i < (1ULL << prefix_diff); i++) {
 669                 err = zap_set_idx_to_blk(zap, sibling+i, nl->l_blkid, tx);
 670                 ASSERT0(err); /* we checked for i/o errors above */
 671         }
 672 
 673         if (hash & (1ULL << (64 - zap_leaf_phys(l)->l_hdr.lh_prefix_len))) {
 674                 /* we want the sibling */
 675                 zap_put_leaf(l);
 676                 *lp = nl;
 677         } else {
 678                 zap_put_leaf(nl);
 679                 *lp = l;
 680         }
 681 
 682         return (0);
 683 }
 684 
 685 static void
 686 zap_put_leaf_maybe_grow_ptrtbl(zap_name_t *zn, zap_leaf_t *l, dmu_tx_t *tx)
 687 {
 688         zap_t *zap = zn->zn_zap;
 689         int shift = zap_f_phys(zap)->zap_ptrtbl.zt_shift;
 690         int leaffull = (zap_leaf_phys(l)->l_hdr.lh_prefix_len == shift &&
 691             zap_leaf_phys(l)->l_hdr.lh_nfree < ZAP_LEAF_LOW_WATER);
 692 
 693         zap_put_leaf(l);
 694 
 695         if (leaffull || zap_f_phys(zap)->zap_ptrtbl.zt_nextblk) {
 696                 int err;
 697 
 698                 /*
 699                  * We are in the middle of growing the pointer table, or
 700                  * this leaf will soon make us grow it.
 701                  */
 702                 if (zap_tryupgradedir(zap, tx) == 0) {
 703                         objset_t *os = zap->zap_objset;
 704                         uint64_t zapobj = zap->zap_object;
 705 
 706                         zap_unlockdir(zap);
 707                         err = zap_lockdir(os, zapobj, tx,
 708                             RW_WRITER, FALSE, FALSE, &zn->zn_zap);
 709                         zap = zn->zn_zap;
 710                         if (err)
 711                                 return;
 712                 }
 713 
 714                 /* could have finished growing while our locks were down */
 715                 if (zap_f_phys(zap)->zap_ptrtbl.zt_shift == shift)
 716                         (void) zap_grow_ptrtbl(zap, tx);
 717         }
 718 }
 719 
 720 static int
 721 fzap_checkname(zap_name_t *zn)
 722 {
 723         if (zn->zn_key_orig_numints * zn->zn_key_intlen > ZAP_MAXNAMELEN)
 724                 return (SET_ERROR(ENAMETOOLONG));
 725         return (0);
 726 }
 727 
 728 static int
 729 fzap_checksize(uint64_t integer_size, uint64_t num_integers)
 730 {
 731         /* Only integer sizes supported by C */
 732         switch (integer_size) {
 733         case 1:
 734         case 2:
 735         case 4:
 736         case 8:
 737                 break;
 738         default:
 739                 return (SET_ERROR(EINVAL));
 740         }
 741 
 742         if (integer_size * num_integers > ZAP_MAXVALUELEN)
 743                 return (E2BIG);
 744 
 745         return (0);
 746 }
 747 
 748 static int
 749 fzap_check(zap_name_t *zn, uint64_t integer_size, uint64_t num_integers)
 750 {
 751         int err;
 752 
 753         if ((err = fzap_checkname(zn)) != 0)
 754                 return (err);
 755         return (fzap_checksize(integer_size, num_integers));
 756 }
 757 
 758 /*
 759  * Routines for manipulating attributes.
 760  */
 761 int
 762 fzap_lookup(zap_name_t *zn,
 763     uint64_t integer_size, uint64_t num_integers, void *buf,
 764     char *realname, int rn_len, boolean_t *ncp)
 765 {
 766         zap_leaf_t *l;
 767         int err;
 768         zap_entry_handle_t zeh;
 769 
 770         if ((err = fzap_checkname(zn)) != 0)
 771                 return (err);
 772 
 773         err = zap_deref_leaf(zn->zn_zap, zn->zn_hash, NULL, RW_READER, &l);
 774         if (err != 0)
 775                 return (err);
 776         err = zap_leaf_lookup(l, zn, &zeh);
 777         if (err == 0) {
 778                 if ((err = fzap_checksize(integer_size, num_integers)) != 0) {
 779                         zap_put_leaf(l);
 780                         return (err);
 781                 }
 782 
 783                 err = zap_entry_read(&zeh, integer_size, num_integers, buf);
 784                 (void) zap_entry_read_name(zn->zn_zap, &zeh, rn_len, realname);
 785                 if (ncp) {
 786                         *ncp = zap_entry_normalization_conflict(&zeh,
 787                             zn, NULL, zn->zn_zap);
 788                 }
 789         }
 790 
 791         zap_put_leaf(l);
 792         return (err);
 793 }
 794 
 795 int
 796 fzap_add_cd(zap_name_t *zn,
 797     uint64_t integer_size, uint64_t num_integers,
 798     const void *val, uint32_t cd, dmu_tx_t *tx)
 799 {
 800         zap_leaf_t *l;
 801         int err;
 802         zap_entry_handle_t zeh;
 803         zap_t *zap = zn->zn_zap;
 804 
 805         ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
 806         ASSERT(!zap->zap_ismicro);
 807         ASSERT(fzap_check(zn, integer_size, num_integers) == 0);
 808 
 809         err = zap_deref_leaf(zap, zn->zn_hash, tx, RW_WRITER, &l);
 810         if (err != 0)
 811                 return (err);
 812 retry:
 813         err = zap_leaf_lookup(l, zn, &zeh);
 814         if (err == 0) {
 815                 err = SET_ERROR(EEXIST);
 816                 goto out;
 817         }
 818         if (err != ENOENT)
 819                 goto out;
 820 
 821         err = zap_entry_create(l, zn, cd,
 822             integer_size, num_integers, val, &zeh);
 823 
 824         if (err == 0) {
 825                 zap_increment_num_entries(zap, 1, tx);
 826         } else if (err == EAGAIN) {
 827                 err = zap_expand_leaf(zn, l, tx, &l);
 828                 zap = zn->zn_zap;    /* zap_expand_leaf() may change zap */
 829                 if (err == 0)
 830                         goto retry;
 831         }
 832 
 833 out:
 834         if (zap != NULL)
 835                 zap_put_leaf_maybe_grow_ptrtbl(zn, l, tx);
 836         return (err);
 837 }
 838 
 839 int
 840 fzap_add(zap_name_t *zn,
 841     uint64_t integer_size, uint64_t num_integers,
 842     const void *val, dmu_tx_t *tx)
 843 {
 844         int err = fzap_check(zn, integer_size, num_integers);
 845         if (err != 0)
 846                 return (err);
 847 
 848         return (fzap_add_cd(zn, integer_size, num_integers,
 849             val, ZAP_NEED_CD, tx));
 850 }
 851 
 852 int
 853 fzap_update(zap_name_t *zn,
 854     int integer_size, uint64_t num_integers, const void *val, dmu_tx_t *tx)
 855 {
 856         zap_leaf_t *l;
 857         int err, create;
 858         zap_entry_handle_t zeh;
 859         zap_t *zap = zn->zn_zap;
 860 
 861         ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
 862         err = fzap_check(zn, integer_size, num_integers);
 863         if (err != 0)
 864                 return (err);
 865 
 866         err = zap_deref_leaf(zap, zn->zn_hash, tx, RW_WRITER, &l);
 867         if (err != 0)
 868                 return (err);
 869 retry:
 870         err = zap_leaf_lookup(l, zn, &zeh);
 871         create = (err == ENOENT);
 872         ASSERT(err == 0 || err == ENOENT);
 873 
 874         if (create) {
 875                 err = zap_entry_create(l, zn, ZAP_NEED_CD,
 876                     integer_size, num_integers, val, &zeh);
 877                 if (err == 0)
 878                         zap_increment_num_entries(zap, 1, tx);
 879         } else {
 880                 err = zap_entry_update(&zeh, integer_size, num_integers, val);
 881         }
 882 
 883         if (err == EAGAIN) {
 884                 err = zap_expand_leaf(zn, l, tx, &l);
 885                 zap = zn->zn_zap;    /* zap_expand_leaf() may change zap */
 886                 if (err == 0)
 887                         goto retry;
 888         }
 889 
 890         if (zap != NULL)
 891                 zap_put_leaf_maybe_grow_ptrtbl(zn, l, tx);
 892         return (err);
 893 }
 894 
 895 int
 896 fzap_length(zap_name_t *zn,
 897     uint64_t *integer_size, uint64_t *num_integers)
 898 {
 899         zap_leaf_t *l;
 900         int err;
 901         zap_entry_handle_t zeh;
 902 
 903         err = zap_deref_leaf(zn->zn_zap, zn->zn_hash, NULL, RW_READER, &l);
 904         if (err != 0)
 905                 return (err);
 906         err = zap_leaf_lookup(l, zn, &zeh);
 907         if (err != 0)
 908                 goto out;
 909 
 910         if (integer_size)
 911                 *integer_size = zeh.zeh_integer_size;
 912         if (num_integers)
 913                 *num_integers = zeh.zeh_num_integers;
 914 out:
 915         zap_put_leaf(l);
 916         return (err);
 917 }
 918 
 919 int
 920 fzap_remove(zap_name_t *zn, dmu_tx_t *tx)
 921 {
 922         zap_leaf_t *l;
 923         int err;
 924         zap_entry_handle_t zeh;
 925 
 926         err = zap_deref_leaf(zn->zn_zap, zn->zn_hash, tx, RW_WRITER, &l);
 927         if (err != 0)
 928                 return (err);
 929         err = zap_leaf_lookup(l, zn, &zeh);
 930         if (err == 0) {
 931                 zap_entry_remove(&zeh);
 932                 zap_increment_num_entries(zn->zn_zap, -1, tx);
 933         }
 934         zap_put_leaf(l);
 935         return (err);
 936 }
 937 
 938 void
 939 fzap_prefetch(zap_name_t *zn)
 940 {
 941         uint64_t idx, blk;
 942         zap_t *zap = zn->zn_zap;
 943         int bs;
 944 
 945         idx = ZAP_HASH_IDX(zn->zn_hash,
 946             zap_f_phys(zap)->zap_ptrtbl.zt_shift);
 947         if (zap_idx_to_blk(zap, idx, &blk) != 0)
 948                 return;
 949         bs = FZAP_BLOCK_SHIFT(zap);
 950         dmu_prefetch(zap->zap_objset, zap->zap_object, 0, blk << bs, 1 << bs,
 951             ZIO_PRIORITY_SYNC_READ);
 952 }
 953 
 954 /*
 955  * Helper functions for consumers.
 956  */
 957 
 958 uint64_t
 959 zap_create_link(objset_t *os, dmu_object_type_t ot, uint64_t parent_obj,
 960     const char *name, dmu_tx_t *tx)
 961 {
 962         uint64_t new_obj;
 963 
 964         VERIFY((new_obj = zap_create(os, ot, DMU_OT_NONE, 0, tx)) > 0);
 965         VERIFY(zap_add(os, parent_obj, name, sizeof (uint64_t), 1, &new_obj,
 966             tx) == 0);
 967 
 968         return (new_obj);
 969 }
 970 
 971 int
 972 zap_value_search(objset_t *os, uint64_t zapobj, uint64_t value, uint64_t mask,
 973     char *name)
 974 {
 975         zap_cursor_t zc;
 976         zap_attribute_t *za;
 977         int err;
 978 
 979         if (mask == 0)
 980                 mask = -1ULL;
 981 
 982         za = kmem_alloc(sizeof (zap_attribute_t), KM_SLEEP);
 983         for (zap_cursor_init(&zc, os, zapobj);
 984             (err = zap_cursor_retrieve(&zc, za)) == 0;
 985             zap_cursor_advance(&zc)) {
 986                 if ((za->za_first_integer & mask) == (value & mask)) {
 987                         (void) strcpy(name, za->za_name);
 988                         break;
 989                 }
 990         }
 991         zap_cursor_fini(&zc);
 992         kmem_free(za, sizeof (zap_attribute_t));
 993         return (err);
 994 }
 995 
 996 int
 997 zap_join(objset_t *os, uint64_t fromobj, uint64_t intoobj, dmu_tx_t *tx)
 998 {
 999         zap_cursor_t zc;
1000         zap_attribute_t za;
1001         int err;
1002 
1003         err = 0;
1004         for (zap_cursor_init(&zc, os, fromobj);
1005             zap_cursor_retrieve(&zc, &za) == 0;
1006             (void) zap_cursor_advance(&zc)) {
1007                 if (za.za_integer_length != 8 || za.za_num_integers != 1) {
1008                         err = SET_ERROR(EINVAL);
1009                         break;
1010                 }
1011                 err = zap_add(os, intoobj, za.za_name,
1012                     8, 1, &za.za_first_integer, tx);
1013                 if (err)
1014                         break;
1015         }
1016         zap_cursor_fini(&zc);
1017         return (err);
1018 }
1019 
1020 int
1021 zap_join_key(objset_t *os, uint64_t fromobj, uint64_t intoobj,
1022     uint64_t value, dmu_tx_t *tx)
1023 {
1024         zap_cursor_t zc;
1025         zap_attribute_t za;
1026         int err;
1027 
1028         err = 0;
1029         for (zap_cursor_init(&zc, os, fromobj);
1030             zap_cursor_retrieve(&zc, &za) == 0;
1031             (void) zap_cursor_advance(&zc)) {
1032                 if (za.za_integer_length != 8 || za.za_num_integers != 1) {
1033                         err = SET_ERROR(EINVAL);
1034                         break;
1035                 }
1036                 err = zap_add(os, intoobj, za.za_name,
1037                     8, 1, &value, tx);
1038                 if (err)
1039                         break;
1040         }
1041         zap_cursor_fini(&zc);
1042         return (err);
1043 }
1044 
1045 int
1046 zap_join_increment(objset_t *os, uint64_t fromobj, uint64_t intoobj,
1047     dmu_tx_t *tx)
1048 {
1049         zap_cursor_t zc;
1050         zap_attribute_t za;
1051         int err;
1052 
1053         err = 0;
1054         for (zap_cursor_init(&zc, os, fromobj);
1055             zap_cursor_retrieve(&zc, &za) == 0;
1056             (void) zap_cursor_advance(&zc)) {
1057                 uint64_t delta = 0;
1058 
1059                 if (za.za_integer_length != 8 || za.za_num_integers != 1) {
1060                         err = SET_ERROR(EINVAL);
1061                         break;
1062                 }
1063 
1064                 err = zap_lookup(os, intoobj, za.za_name, 8, 1, &delta);
1065                 if (err != 0 && err != ENOENT)
1066                         break;
1067                 delta += za.za_first_integer;
1068                 err = zap_update(os, intoobj, za.za_name, 8, 1, &delta, tx);
1069                 if (err)
1070                         break;
1071         }
1072         zap_cursor_fini(&zc);
1073         return (err);
1074 }
1075 
1076 int
1077 zap_add_int(objset_t *os, uint64_t obj, uint64_t value, dmu_tx_t *tx)
1078 {
1079         char name[20];
1080 
1081         (void) snprintf(name, sizeof (name), "%llx", (longlong_t)value);
1082         return (zap_add(os, obj, name, 8, 1, &value, tx));
1083 }
1084 
1085 int
1086 zap_remove_int(objset_t *os, uint64_t obj, uint64_t value, dmu_tx_t *tx)
1087 {
1088         char name[20];
1089 
1090         (void) snprintf(name, sizeof (name), "%llx", (longlong_t)value);
1091         return (zap_remove(os, obj, name, tx));
1092 }
1093 
1094 int
1095 zap_lookup_int(objset_t *os, uint64_t obj, uint64_t value)
1096 {
1097         char name[20];
1098 
1099         (void) snprintf(name, sizeof (name), "%llx", (longlong_t)value);
1100         return (zap_lookup(os, obj, name, 8, 1, &value));
1101 }
1102 
1103 int
1104 zap_add_int_key(objset_t *os, uint64_t obj,
1105     uint64_t key, uint64_t value, dmu_tx_t *tx)
1106 {
1107         char name[20];
1108 
1109         (void) snprintf(name, sizeof (name), "%llx", (longlong_t)key);
1110         return (zap_add(os, obj, name, 8, 1, &value, tx));
1111 }
1112 
1113 int
1114 zap_update_int_key(objset_t *os, uint64_t obj,
1115     uint64_t key, uint64_t value, dmu_tx_t *tx)
1116 {
1117         char name[20];
1118 
1119         (void) snprintf(name, sizeof (name), "%llx", (longlong_t)key);
1120         return (zap_update(os, obj, name, 8, 1, &value, tx));
1121 }
1122 
1123 int
1124 zap_lookup_int_key(objset_t *os, uint64_t obj, uint64_t key, uint64_t *valuep)
1125 {
1126         char name[20];
1127 
1128         (void) snprintf(name, sizeof (name), "%llx", (longlong_t)key);
1129         return (zap_lookup(os, obj, name, 8, 1, valuep));
1130 }
1131 
1132 int
1133 zap_increment(objset_t *os, uint64_t obj, const char *name, int64_t delta,
1134     dmu_tx_t *tx)
1135 {
1136         uint64_t value = 0;
1137         int err;
1138 
1139         if (delta == 0)
1140                 return (0);
1141 
1142         err = zap_lookup(os, obj, name, 8, 1, &value);
1143         if (err != 0 && err != ENOENT)
1144                 return (err);
1145         value += delta;
1146         if (value == 0)
1147                 err = zap_remove(os, obj, name, tx);
1148         else
1149                 err = zap_update(os, obj, name, 8, 1, &value, tx);
1150         return (err);
1151 }
1152 
1153 int
1154 zap_increment_int(objset_t *os, uint64_t obj, uint64_t key, int64_t delta,
1155     dmu_tx_t *tx)
1156 {
1157         char name[20];
1158 
1159         (void) snprintf(name, sizeof (name), "%llx", (longlong_t)key);
1160         return (zap_increment(os, obj, name, delta, tx));
1161 }
1162 
1163 /*
1164  * Routines for iterating over the attributes.
1165  */
1166 
1167 int
1168 fzap_cursor_retrieve(zap_t *zap, zap_cursor_t *zc, zap_attribute_t *za)
1169 {
1170         int err = ENOENT;
1171         zap_entry_handle_t zeh;
1172         zap_leaf_t *l;
1173 
1174         /* retrieve the next entry at or after zc_hash/zc_cd */
1175         /* if no entry, return ENOENT */
1176 
1177         if (zc->zc_leaf &&
1178             (ZAP_HASH_IDX(zc->zc_hash,
1179             zap_leaf_phys(zc->zc_leaf)->l_hdr.lh_prefix_len) !=
1180             zap_leaf_phys(zc->zc_leaf)->l_hdr.lh_prefix)) {
1181                 rw_enter(&zc->zc_leaf->l_rwlock, RW_READER);
1182                 zap_put_leaf(zc->zc_leaf);
1183                 zc->zc_leaf = NULL;
1184         }
1185 
1186 again:
1187         if (zc->zc_leaf == NULL) {
1188                 err = zap_deref_leaf(zap, zc->zc_hash, NULL, RW_READER,
1189                     &zc->zc_leaf);
1190                 if (err != 0)
1191                         return (err);
1192         } else {
1193                 rw_enter(&zc->zc_leaf->l_rwlock, RW_READER);
1194         }
1195         l = zc->zc_leaf;
1196 
1197         err = zap_leaf_lookup_closest(l, zc->zc_hash, zc->zc_cd, &zeh);
1198 
1199         if (err == ENOENT) {
1200                 uint64_t nocare =
1201                     (1ULL << (64 - zap_leaf_phys(l)->l_hdr.lh_prefix_len)) - 1;
1202                 zc->zc_hash = (zc->zc_hash & ~nocare) + nocare + 1;
1203                 zc->zc_cd = 0;
1204                 if (zap_leaf_phys(l)->l_hdr.lh_prefix_len == 0 ||
1205                     zc->zc_hash == 0) {
1206                         zc->zc_hash = -1ULL;
1207                 } else {
1208                         zap_put_leaf(zc->zc_leaf);
1209                         zc->zc_leaf = NULL;
1210                         goto again;
1211                 }
1212         }
1213 
1214         if (err == 0) {
1215                 zc->zc_hash = zeh.zeh_hash;
1216                 zc->zc_cd = zeh.zeh_cd;
1217                 za->za_integer_length = zeh.zeh_integer_size;
1218                 za->za_num_integers = zeh.zeh_num_integers;
1219                 if (zeh.zeh_num_integers == 0) {
1220                         za->za_first_integer = 0;
1221                 } else {
1222                         err = zap_entry_read(&zeh, 8, 1, &za->za_first_integer);
1223                         ASSERT(err == 0 || err == EOVERFLOW);
1224                 }
1225                 err = zap_entry_read_name(zap, &zeh,
1226                     sizeof (za->za_name), za->za_name);
1227                 ASSERT(err == 0);
1228 
1229                 za->za_normalization_conflict =
1230                     zap_entry_normalization_conflict(&zeh,
1231                     NULL, za->za_name, zap);
1232         }
1233         rw_exit(&zc->zc_leaf->l_rwlock);
1234         return (err);
1235 }
1236 
1237 static void
1238 zap_stats_ptrtbl(zap_t *zap, uint64_t *tbl, int len, zap_stats_t *zs)
1239 {
1240         int i, err;
1241         uint64_t lastblk = 0;
1242 
1243         /*
1244          * NB: if a leaf has more pointers than an entire ptrtbl block
1245          * can hold, then it'll be accounted for more than once, since
1246          * we won't have lastblk.
1247          */
1248         for (i = 0; i < len; i++) {
1249                 zap_leaf_t *l;
1250 
1251                 if (tbl[i] == lastblk)
1252                         continue;
1253                 lastblk = tbl[i];
1254 
1255                 err = zap_get_leaf_byblk(zap, tbl[i], NULL, RW_READER, &l);
1256                 if (err == 0) {
1257                         zap_leaf_stats(zap, l, zs);
1258                         zap_put_leaf(l);
1259                 }
1260         }
1261 }
1262 
1263 void
1264 fzap_get_stats(zap_t *zap, zap_stats_t *zs)
1265 {
1266         int bs = FZAP_BLOCK_SHIFT(zap);
1267         zs->zs_blocksize = 1ULL << bs;
1268 
1269         /*
1270          * Set zap_phys_t fields
1271          */
1272         zs->zs_num_leafs = zap_f_phys(zap)->zap_num_leafs;
1273         zs->zs_num_entries = zap_f_phys(zap)->zap_num_entries;
1274         zs->zs_num_blocks = zap_f_phys(zap)->zap_freeblk;
1275         zs->zs_block_type = zap_f_phys(zap)->zap_block_type;
1276         zs->zs_magic = zap_f_phys(zap)->zap_magic;
1277         zs->zs_salt = zap_f_phys(zap)->zap_salt;
1278 
1279         /*
1280          * Set zap_ptrtbl fields
1281          */
1282         zs->zs_ptrtbl_len = 1ULL << zap_f_phys(zap)->zap_ptrtbl.zt_shift;
1283         zs->zs_ptrtbl_nextblk = zap_f_phys(zap)->zap_ptrtbl.zt_nextblk;
1284         zs->zs_ptrtbl_blks_copied =
1285             zap_f_phys(zap)->zap_ptrtbl.zt_blks_copied;
1286         zs->zs_ptrtbl_zt_blk = zap_f_phys(zap)->zap_ptrtbl.zt_blk;
1287         zs->zs_ptrtbl_zt_numblks = zap_f_phys(zap)->zap_ptrtbl.zt_numblks;
1288         zs->zs_ptrtbl_zt_shift = zap_f_phys(zap)->zap_ptrtbl.zt_shift;
1289 
1290         if (zap_f_phys(zap)->zap_ptrtbl.zt_numblks == 0) {
1291                 /* the ptrtbl is entirely in the header block. */
1292                 zap_stats_ptrtbl(zap, &ZAP_EMBEDDED_PTRTBL_ENT(zap, 0),
1293                     1 << ZAP_EMBEDDED_PTRTBL_SHIFT(zap), zs);
1294         } else {
1295                 int b;
1296 
1297                 dmu_prefetch(zap->zap_objset, zap->zap_object, 0,
1298                     zap_f_phys(zap)->zap_ptrtbl.zt_blk << bs,
1299                     zap_f_phys(zap)->zap_ptrtbl.zt_numblks << bs,
1300                     ZIO_PRIORITY_SYNC_READ);
1301 
1302                 for (b = 0; b < zap_f_phys(zap)->zap_ptrtbl.zt_numblks;
1303                     b++) {
1304                         dmu_buf_t *db;
1305                         int err;
1306 
1307                         err = dmu_buf_hold(zap->zap_objset, zap->zap_object,
1308                             (zap_f_phys(zap)->zap_ptrtbl.zt_blk + b) << bs,
1309                             FTAG, &db, DMU_READ_NO_PREFETCH);
1310                         if (err == 0) {
1311                                 zap_stats_ptrtbl(zap, db->db_data,
1312                                     1<<(bs-3), zs);
1313                                 dmu_buf_rele(db, FTAG);
1314                         }
1315                 }
1316         }
1317 }
1318 
1319 int
1320 fzap_count_write(zap_name_t *zn, int add, uint64_t *towrite,
1321     uint64_t *tooverwrite)
1322 {
1323         zap_t *zap = zn->zn_zap;
1324         zap_leaf_t *l;
1325         int err;
1326 
1327         /*
1328          * Account for the header block of the fatzap.
1329          */
1330         if (!add && dmu_buf_freeable(zap->zap_dbuf)) {
1331                 *tooverwrite += zap->zap_dbuf->db_size;
1332         } else {
1333                 *towrite += zap->zap_dbuf->db_size;
1334         }
1335 
1336         /*
1337          * Account for the pointer table blocks.
1338          * If we are adding we need to account for the following cases :
1339          * - If the pointer table is embedded, this operation could force an
1340          *   external pointer table.
1341          * - If this already has an external pointer table this operation
1342          *   could extend the table.
1343          */
1344         if (add) {
1345                 if (zap_f_phys(zap)->zap_ptrtbl.zt_blk == 0)
1346                         *towrite += zap->zap_dbuf->db_size;
1347                 else
1348                         *towrite += (zap->zap_dbuf->db_size * 3);
1349         }
1350 
1351         /*
1352          * Now, check if the block containing leaf is freeable
1353          * and account accordingly.
1354          */
1355         err = zap_deref_leaf(zap, zn->zn_hash, NULL, RW_READER, &l);
1356         if (err != 0) {
1357                 return (err);
1358         }
1359 
1360         if (!add && dmu_buf_freeable(l->l_dbuf)) {
1361                 *tooverwrite += l->l_dbuf->db_size;
1362         } else {
1363                 /*
1364                  * If this an add operation, the leaf block could split.
1365                  * Hence, we need to account for an additional leaf block.
1366                  */
1367                 *towrite += (add ? 2 : 1) * l->l_dbuf->db_size;
1368         }
1369 
1370         zap_put_leaf(l);
1371         return (0);
1372 }