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) 2013 by Delphix. All rights reserved.
  24  */
  25 
  26 #include <sys/zfs_context.h>
  27 #include <sys/dbuf.h>
  28 #include <sys/dnode.h>
  29 #include <sys/dmu.h>
  30 #include <sys/dmu_impl.h>
  31 #include <sys/dmu_tx.h>
  32 #include <sys/dmu_objset.h>
  33 #include <sys/dsl_dir.h>
  34 #include <sys/dsl_dataset.h>
  35 #include <sys/spa.h>
  36 #include <sys/zio.h>
  37 #include <sys/dmu_zfetch.h>
  38 
  39 static int free_range_compar(const void *node1, const void *node2);
  40 
  41 static kmem_cache_t *dnode_cache;
  42 /*
  43  * Define DNODE_STATS to turn on statistic gathering. By default, it is only
  44  * turned on when DEBUG is also defined.
  45  */
  46 #ifdef  DEBUG
  47 #define DNODE_STATS
  48 #endif  /* DEBUG */
  49 
  50 #ifdef  DNODE_STATS
  51 #define DNODE_STAT_ADD(stat)                    ((stat)++)
  52 #else
  53 #define DNODE_STAT_ADD(stat)                    /* nothing */
  54 #endif  /* DNODE_STATS */
  55 
  56 static dnode_phys_t dnode_phys_zero;
  57 
  58 int zfs_default_bs = SPA_MINBLOCKSHIFT;
  59 int zfs_default_ibs = DN_MAX_INDBLKSHIFT;
  60 
  61 static kmem_cbrc_t dnode_move(void *, void *, size_t, void *);
  62 
  63 /* ARGSUSED */
  64 static int
  65 dnode_cons(void *arg, void *unused, int kmflag)
  66 {
  67         dnode_t *dn = arg;
  68         int i;
  69 
  70         rw_init(&dn->dn_struct_rwlock, NULL, RW_DEFAULT, NULL);
  71         mutex_init(&dn->dn_mtx, NULL, MUTEX_DEFAULT, NULL);
  72         mutex_init(&dn->dn_dbufs_mtx, NULL, MUTEX_DEFAULT, NULL);
  73         cv_init(&dn->dn_notxholds, NULL, CV_DEFAULT, NULL);
  74 
  75         /*
  76          * Every dbuf has a reference, and dropping a tracked reference is
  77          * O(number of references), so don't track dn_holds.
  78          */
  79         refcount_create_untracked(&dn->dn_holds);
  80         refcount_create(&dn->dn_tx_holds);
  81         list_link_init(&dn->dn_link);
  82 
  83         bzero(&dn->dn_next_nblkptr[0], sizeof (dn->dn_next_nblkptr));
  84         bzero(&dn->dn_next_nlevels[0], sizeof (dn->dn_next_nlevels));
  85         bzero(&dn->dn_next_indblkshift[0], sizeof (dn->dn_next_indblkshift));
  86         bzero(&dn->dn_next_bonustype[0], sizeof (dn->dn_next_bonustype));
  87         bzero(&dn->dn_rm_spillblk[0], sizeof (dn->dn_rm_spillblk));
  88         bzero(&dn->dn_next_bonuslen[0], sizeof (dn->dn_next_bonuslen));
  89         bzero(&dn->dn_next_blksz[0], sizeof (dn->dn_next_blksz));
  90 
  91         for (i = 0; i < TXG_SIZE; i++) {
  92                 list_link_init(&dn->dn_dirty_link[i]);
  93                 avl_create(&dn->dn_ranges[i], free_range_compar,
  94                     sizeof (free_range_t),
  95                     offsetof(struct free_range, fr_node));
  96                 list_create(&dn->dn_dirty_records[i],
  97                     sizeof (dbuf_dirty_record_t),
  98                     offsetof(dbuf_dirty_record_t, dr_dirty_node));
  99         }
 100 
 101         dn->dn_allocated_txg = 0;
 102         dn->dn_free_txg = 0;
 103         dn->dn_assigned_txg = 0;
 104         dn->dn_dirtyctx = 0;
 105         dn->dn_dirtyctx_firstset = NULL;
 106         dn->dn_bonus = NULL;
 107         dn->dn_have_spill = B_FALSE;
 108         dn->dn_zio = NULL;
 109         dn->dn_oldused = 0;
 110         dn->dn_oldflags = 0;
 111         dn->dn_olduid = 0;
 112         dn->dn_oldgid = 0;
 113         dn->dn_newuid = 0;
 114         dn->dn_newgid = 0;
 115         dn->dn_id_flags = 0;
 116 
 117         dn->dn_dbufs_count = 0;
 118         list_create(&dn->dn_dbufs, sizeof (dmu_buf_impl_t),
 119             offsetof(dmu_buf_impl_t, db_link));
 120 
 121         dn->dn_moved = 0;
 122         return (0);
 123 }
 124 
 125 /* ARGSUSED */
 126 static void
 127 dnode_dest(void *arg, void *unused)
 128 {
 129         int i;
 130         dnode_t *dn = arg;
 131 
 132         rw_destroy(&dn->dn_struct_rwlock);
 133         mutex_destroy(&dn->dn_mtx);
 134         mutex_destroy(&dn->dn_dbufs_mtx);
 135         cv_destroy(&dn->dn_notxholds);
 136         refcount_destroy(&dn->dn_holds);
 137         refcount_destroy(&dn->dn_tx_holds);
 138         ASSERT(!list_link_active(&dn->dn_link));
 139 
 140         for (i = 0; i < TXG_SIZE; i++) {
 141                 ASSERT(!list_link_active(&dn->dn_dirty_link[i]));
 142                 avl_destroy(&dn->dn_ranges[i]);
 143                 list_destroy(&dn->dn_dirty_records[i]);
 144                 ASSERT0(dn->dn_next_nblkptr[i]);
 145                 ASSERT0(dn->dn_next_nlevels[i]);
 146                 ASSERT0(dn->dn_next_indblkshift[i]);
 147                 ASSERT0(dn->dn_next_bonustype[i]);
 148                 ASSERT0(dn->dn_rm_spillblk[i]);
 149                 ASSERT0(dn->dn_next_bonuslen[i]);
 150                 ASSERT0(dn->dn_next_blksz[i]);
 151         }
 152 
 153         ASSERT0(dn->dn_allocated_txg);
 154         ASSERT0(dn->dn_free_txg);
 155         ASSERT0(dn->dn_assigned_txg);
 156         ASSERT0(dn->dn_dirtyctx);
 157         ASSERT3P(dn->dn_dirtyctx_firstset, ==, NULL);
 158         ASSERT3P(dn->dn_bonus, ==, NULL);
 159         ASSERT(!dn->dn_have_spill);
 160         ASSERT3P(dn->dn_zio, ==, NULL);
 161         ASSERT0(dn->dn_oldused);
 162         ASSERT0(dn->dn_oldflags);
 163         ASSERT0(dn->dn_olduid);
 164         ASSERT0(dn->dn_oldgid);
 165         ASSERT0(dn->dn_newuid);
 166         ASSERT0(dn->dn_newgid);
 167         ASSERT0(dn->dn_id_flags);
 168 
 169         ASSERT0(dn->dn_dbufs_count);
 170         list_destroy(&dn->dn_dbufs);
 171 }
 172 
 173 void
 174 dnode_init(void)
 175 {
 176         ASSERT(dnode_cache == NULL);
 177         dnode_cache = kmem_cache_create("dnode_t",
 178             sizeof (dnode_t),
 179             0, dnode_cons, dnode_dest, NULL, NULL, NULL, 0);
 180         kmem_cache_set_move(dnode_cache, dnode_move);
 181 }
 182 
 183 void
 184 dnode_fini(void)
 185 {
 186         kmem_cache_destroy(dnode_cache);
 187         dnode_cache = NULL;
 188 }
 189 
 190 
 191 #ifdef ZFS_DEBUG
 192 void
 193 dnode_verify(dnode_t *dn)
 194 {
 195         int drop_struct_lock = FALSE;
 196 
 197         ASSERT(dn->dn_phys);
 198         ASSERT(dn->dn_objset);
 199         ASSERT(dn->dn_handle->dnh_dnode == dn);
 200 
 201         ASSERT(DMU_OT_IS_VALID(dn->dn_phys->dn_type));
 202 
 203         if (!(zfs_flags & ZFS_DEBUG_DNODE_VERIFY))
 204                 return;
 205 
 206         if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
 207                 rw_enter(&dn->dn_struct_rwlock, RW_READER);
 208                 drop_struct_lock = TRUE;
 209         }
 210         if (dn->dn_phys->dn_type != DMU_OT_NONE || dn->dn_allocated_txg != 0) {
 211                 int i;
 212                 ASSERT3U(dn->dn_indblkshift, >=, 0);
 213                 ASSERT3U(dn->dn_indblkshift, <=, SPA_MAXBLOCKSHIFT);
 214                 if (dn->dn_datablkshift) {
 215                         ASSERT3U(dn->dn_datablkshift, >=, SPA_MINBLOCKSHIFT);
 216                         ASSERT3U(dn->dn_datablkshift, <=, SPA_MAXBLOCKSHIFT);
 217                         ASSERT3U(1<<dn->dn_datablkshift, ==, dn->dn_datablksz);
 218                 }
 219                 ASSERT3U(dn->dn_nlevels, <=, 30);
 220                 ASSERT(DMU_OT_IS_VALID(dn->dn_type));
 221                 ASSERT3U(dn->dn_nblkptr, >=, 1);
 222                 ASSERT3U(dn->dn_nblkptr, <=, DN_MAX_NBLKPTR);
 223                 ASSERT3U(dn->dn_bonuslen, <=, DN_MAX_BONUSLEN);
 224                 ASSERT3U(dn->dn_datablksz, ==,
 225                     dn->dn_datablkszsec << SPA_MINBLOCKSHIFT);
 226                 ASSERT3U(ISP2(dn->dn_datablksz), ==, dn->dn_datablkshift != 0);
 227                 ASSERT3U((dn->dn_nblkptr - 1) * sizeof (blkptr_t) +
 228                     dn->dn_bonuslen, <=, DN_MAX_BONUSLEN);
 229                 for (i = 0; i < TXG_SIZE; i++) {
 230                         ASSERT3U(dn->dn_next_nlevels[i], <=, dn->dn_nlevels);
 231                 }
 232         }
 233         if (dn->dn_phys->dn_type != DMU_OT_NONE)
 234                 ASSERT3U(dn->dn_phys->dn_nlevels, <=, dn->dn_nlevels);
 235         ASSERT(DMU_OBJECT_IS_SPECIAL(dn->dn_object) || dn->dn_dbuf != NULL);
 236         if (dn->dn_dbuf != NULL) {
 237                 ASSERT3P(dn->dn_phys, ==,
 238                     (dnode_phys_t *)dn->dn_dbuf->db.db_data +
 239                     (dn->dn_object % (dn->dn_dbuf->db.db_size >> DNODE_SHIFT)));
 240         }
 241         if (drop_struct_lock)
 242                 rw_exit(&dn->dn_struct_rwlock);
 243 }
 244 #endif
 245 
 246 void
 247 dnode_byteswap(dnode_phys_t *dnp)
 248 {
 249         uint64_t *buf64 = (void*)&dnp->dn_blkptr;
 250         int i;
 251 
 252         if (dnp->dn_type == DMU_OT_NONE) {
 253                 bzero(dnp, sizeof (dnode_phys_t));
 254                 return;
 255         }
 256 
 257         dnp->dn_datablkszsec = BSWAP_16(dnp->dn_datablkszsec);
 258         dnp->dn_bonuslen = BSWAP_16(dnp->dn_bonuslen);
 259         dnp->dn_maxblkid = BSWAP_64(dnp->dn_maxblkid);
 260         dnp->dn_used = BSWAP_64(dnp->dn_used);
 261 
 262         /*
 263          * dn_nblkptr is only one byte, so it's OK to read it in either
 264          * byte order.  We can't read dn_bouslen.
 265          */
 266         ASSERT(dnp->dn_indblkshift <= SPA_MAXBLOCKSHIFT);
 267         ASSERT(dnp->dn_nblkptr <= DN_MAX_NBLKPTR);
 268         for (i = 0; i < dnp->dn_nblkptr * sizeof (blkptr_t)/8; i++)
 269                 buf64[i] = BSWAP_64(buf64[i]);
 270 
 271         /*
 272          * OK to check dn_bonuslen for zero, because it won't matter if
 273          * we have the wrong byte order.  This is necessary because the
 274          * dnode dnode is smaller than a regular dnode.
 275          */
 276         if (dnp->dn_bonuslen != 0) {
 277                 /*
 278                  * Note that the bonus length calculated here may be
 279                  * longer than the actual bonus buffer.  This is because
 280                  * we always put the bonus buffer after the last block
 281                  * pointer (instead of packing it against the end of the
 282                  * dnode buffer).
 283                  */
 284                 int off = (dnp->dn_nblkptr-1) * sizeof (blkptr_t);
 285                 size_t len = DN_MAX_BONUSLEN - off;
 286                 ASSERT(DMU_OT_IS_VALID(dnp->dn_bonustype));
 287                 dmu_object_byteswap_t byteswap =
 288                     DMU_OT_BYTESWAP(dnp->dn_bonustype);
 289                 dmu_ot_byteswap[byteswap].ob_func(dnp->dn_bonus + off, len);
 290         }
 291 
 292         /* Swap SPILL block if we have one */
 293         if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR)
 294                 byteswap_uint64_array(&dnp->dn_spill, sizeof (blkptr_t));
 295 
 296 }
 297 
 298 void
 299 dnode_buf_byteswap(void *vbuf, size_t size)
 300 {
 301         dnode_phys_t *buf = vbuf;
 302         int i;
 303 
 304         ASSERT3U(sizeof (dnode_phys_t), ==, (1<<DNODE_SHIFT));
 305         ASSERT((size & (sizeof (dnode_phys_t)-1)) == 0);
 306 
 307         size >>= DNODE_SHIFT;
 308         for (i = 0; i < size; i++) {
 309                 dnode_byteswap(buf);
 310                 buf++;
 311         }
 312 }
 313 
 314 static int
 315 free_range_compar(const void *node1, const void *node2)
 316 {
 317         const free_range_t *rp1 = node1;
 318         const free_range_t *rp2 = node2;
 319 
 320         if (rp1->fr_blkid < rp2->fr_blkid)
 321                 return (-1);
 322         else if (rp1->fr_blkid > rp2->fr_blkid)
 323                 return (1);
 324         else return (0);
 325 }
 326 
 327 void
 328 dnode_setbonuslen(dnode_t *dn, int newsize, dmu_tx_t *tx)
 329 {
 330         ASSERT3U(refcount_count(&dn->dn_holds), >=, 1);
 331 
 332         dnode_setdirty(dn, tx);
 333         rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
 334         ASSERT3U(newsize, <=, DN_MAX_BONUSLEN -
 335             (dn->dn_nblkptr-1) * sizeof (blkptr_t));
 336         dn->dn_bonuslen = newsize;
 337         if (newsize == 0)
 338                 dn->dn_next_bonuslen[tx->tx_txg & TXG_MASK] = DN_ZERO_BONUSLEN;
 339         else
 340                 dn->dn_next_bonuslen[tx->tx_txg & TXG_MASK] = dn->dn_bonuslen;
 341         rw_exit(&dn->dn_struct_rwlock);
 342 }
 343 
 344 void
 345 dnode_setbonus_type(dnode_t *dn, dmu_object_type_t newtype, dmu_tx_t *tx)
 346 {
 347         ASSERT3U(refcount_count(&dn->dn_holds), >=, 1);
 348         dnode_setdirty(dn, tx);
 349         rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
 350         dn->dn_bonustype = newtype;
 351         dn->dn_next_bonustype[tx->tx_txg & TXG_MASK] = dn->dn_bonustype;
 352         rw_exit(&dn->dn_struct_rwlock);
 353 }
 354 
 355 void
 356 dnode_rm_spill(dnode_t *dn, dmu_tx_t *tx)
 357 {
 358         ASSERT3U(refcount_count(&dn->dn_holds), >=, 1);
 359         ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
 360         dnode_setdirty(dn, tx);
 361         dn->dn_rm_spillblk[tx->tx_txg&TXG_MASK] = DN_KILL_SPILLBLK;
 362         dn->dn_have_spill = B_FALSE;
 363 }
 364 
 365 static void
 366 dnode_setdblksz(dnode_t *dn, int size)
 367 {
 368         ASSERT0(P2PHASE(size, SPA_MINBLOCKSIZE));
 369         ASSERT3U(size, <=, SPA_MAXBLOCKSIZE);
 370         ASSERT3U(size, >=, SPA_MINBLOCKSIZE);
 371         ASSERT3U(size >> SPA_MINBLOCKSHIFT, <,
 372             1<<(sizeof (dn->dn_phys->dn_datablkszsec) * 8));
 373         dn->dn_datablksz = size;
 374         dn->dn_datablkszsec = size >> SPA_MINBLOCKSHIFT;
 375         dn->dn_datablkshift = ISP2(size) ? highbit(size - 1) : 0;
 376 }
 377 
 378 static dnode_t *
 379 dnode_create(objset_t *os, dnode_phys_t *dnp, dmu_buf_impl_t *db,
 380     uint64_t object, dnode_handle_t *dnh)
 381 {
 382         dnode_t *dn = kmem_cache_alloc(dnode_cache, KM_SLEEP);
 383 
 384         ASSERT(!POINTER_IS_VALID(dn->dn_objset));
 385         dn->dn_moved = 0;
 386 
 387         /*
 388          * Defer setting dn_objset until the dnode is ready to be a candidate
 389          * for the dnode_move() callback.
 390          */
 391         dn->dn_object = object;
 392         dn->dn_dbuf = db;
 393         dn->dn_handle = dnh;
 394         dn->dn_phys = dnp;
 395 
 396         if (dnp->dn_datablkszsec) {
 397                 dnode_setdblksz(dn, dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT);
 398         } else {
 399                 dn->dn_datablksz = 0;
 400                 dn->dn_datablkszsec = 0;
 401                 dn->dn_datablkshift = 0;
 402         }
 403         dn->dn_indblkshift = dnp->dn_indblkshift;
 404         dn->dn_nlevels = dnp->dn_nlevels;
 405         dn->dn_type = dnp->dn_type;
 406         dn->dn_nblkptr = dnp->dn_nblkptr;
 407         dn->dn_checksum = dnp->dn_checksum;
 408         dn->dn_compress = dnp->dn_compress;
 409         dn->dn_bonustype = dnp->dn_bonustype;
 410         dn->dn_bonuslen = dnp->dn_bonuslen;
 411         dn->dn_maxblkid = dnp->dn_maxblkid;
 412         dn->dn_have_spill = ((dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) != 0);
 413         dn->dn_id_flags = 0;
 414 
 415         dmu_zfetch_init(&dn->dn_zfetch, dn);
 416 
 417         ASSERT(DMU_OT_IS_VALID(dn->dn_phys->dn_type));
 418 
 419         mutex_enter(&os->os_lock);
 420         list_insert_head(&os->os_dnodes, dn);
 421         membar_producer();
 422         /*
 423          * Everything else must be valid before assigning dn_objset makes the
 424          * dnode eligible for dnode_move().
 425          */
 426         dn->dn_objset = os;
 427         mutex_exit(&os->os_lock);
 428 
 429         arc_space_consume(sizeof (dnode_t), ARC_SPACE_OTHER);
 430         return (dn);
 431 }
 432 
 433 /*
 434  * Caller must be holding the dnode handle, which is released upon return.
 435  */
 436 static void
 437 dnode_destroy(dnode_t *dn)
 438 {
 439         objset_t *os = dn->dn_objset;
 440 
 441         ASSERT((dn->dn_id_flags & DN_ID_NEW_EXIST) == 0);
 442 
 443         mutex_enter(&os->os_lock);
 444         POINTER_INVALIDATE(&dn->dn_objset);
 445         list_remove(&os->os_dnodes, dn);
 446         mutex_exit(&os->os_lock);
 447 
 448         /* the dnode can no longer move, so we can release the handle */
 449         zrl_remove(&dn->dn_handle->dnh_zrlock);
 450 
 451         dn->dn_allocated_txg = 0;
 452         dn->dn_free_txg = 0;
 453         dn->dn_assigned_txg = 0;
 454 
 455         dn->dn_dirtyctx = 0;
 456         if (dn->dn_dirtyctx_firstset != NULL) {
 457                 kmem_free(dn->dn_dirtyctx_firstset, 1);
 458                 dn->dn_dirtyctx_firstset = NULL;
 459         }
 460         if (dn->dn_bonus != NULL) {
 461                 mutex_enter(&dn->dn_bonus->db_mtx);
 462                 dbuf_evict(dn->dn_bonus);
 463                 dn->dn_bonus = NULL;
 464         }
 465         dn->dn_zio = NULL;
 466 
 467         dn->dn_have_spill = B_FALSE;
 468         dn->dn_oldused = 0;
 469         dn->dn_oldflags = 0;
 470         dn->dn_olduid = 0;
 471         dn->dn_oldgid = 0;
 472         dn->dn_newuid = 0;
 473         dn->dn_newgid = 0;
 474         dn->dn_id_flags = 0;
 475 
 476         dmu_zfetch_rele(&dn->dn_zfetch);
 477         kmem_cache_free(dnode_cache, dn);
 478         arc_space_return(sizeof (dnode_t), ARC_SPACE_OTHER);
 479 }
 480 
 481 void
 482 dnode_allocate(dnode_t *dn, dmu_object_type_t ot, int blocksize, int ibs,
 483     dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
 484 {
 485         int i;
 486 
 487         if (blocksize == 0)
 488                 blocksize = 1 << zfs_default_bs;
 489         else if (blocksize > SPA_MAXBLOCKSIZE)
 490                 blocksize = SPA_MAXBLOCKSIZE;
 491         else
 492                 blocksize = P2ROUNDUP(blocksize, SPA_MINBLOCKSIZE);
 493 
 494         if (ibs == 0)
 495                 ibs = zfs_default_ibs;
 496 
 497         ibs = MIN(MAX(ibs, DN_MIN_INDBLKSHIFT), DN_MAX_INDBLKSHIFT);
 498 
 499         dprintf("os=%p obj=%llu txg=%llu blocksize=%d ibs=%d\n", dn->dn_objset,
 500             dn->dn_object, tx->tx_txg, blocksize, ibs);
 501 
 502         ASSERT(dn->dn_type == DMU_OT_NONE);
 503         ASSERT(bcmp(dn->dn_phys, &dnode_phys_zero, sizeof (dnode_phys_t)) == 0);
 504         ASSERT(dn->dn_phys->dn_type == DMU_OT_NONE);
 505         ASSERT(ot != DMU_OT_NONE);
 506         ASSERT(DMU_OT_IS_VALID(ot));
 507         ASSERT((bonustype == DMU_OT_NONE && bonuslen == 0) ||
 508             (bonustype == DMU_OT_SA && bonuslen == 0) ||
 509             (bonustype != DMU_OT_NONE && bonuslen != 0));
 510         ASSERT(DMU_OT_IS_VALID(bonustype));
 511         ASSERT3U(bonuslen, <=, DN_MAX_BONUSLEN);
 512         ASSERT(dn->dn_type == DMU_OT_NONE);
 513         ASSERT0(dn->dn_maxblkid);
 514         ASSERT0(dn->dn_allocated_txg);
 515         ASSERT0(dn->dn_assigned_txg);
 516         ASSERT(refcount_is_zero(&dn->dn_tx_holds));
 517         ASSERT3U(refcount_count(&dn->dn_holds), <=, 1);
 518         ASSERT3P(list_head(&dn->dn_dbufs), ==, NULL);
 519 
 520         for (i = 0; i < TXG_SIZE; i++) {
 521                 ASSERT0(dn->dn_next_nblkptr[i]);
 522                 ASSERT0(dn->dn_next_nlevels[i]);
 523                 ASSERT0(dn->dn_next_indblkshift[i]);
 524                 ASSERT0(dn->dn_next_bonuslen[i]);
 525                 ASSERT0(dn->dn_next_bonustype[i]);
 526                 ASSERT0(dn->dn_rm_spillblk[i]);
 527                 ASSERT0(dn->dn_next_blksz[i]);
 528                 ASSERT(!list_link_active(&dn->dn_dirty_link[i]));
 529                 ASSERT3P(list_head(&dn->dn_dirty_records[i]), ==, NULL);
 530                 ASSERT0(avl_numnodes(&dn->dn_ranges[i]));
 531         }
 532 
 533         dn->dn_type = ot;
 534         dnode_setdblksz(dn, blocksize);
 535         dn->dn_indblkshift = ibs;
 536         dn->dn_nlevels = 1;
 537         if (bonustype == DMU_OT_SA) /* Maximize bonus space for SA */
 538                 dn->dn_nblkptr = 1;
 539         else
 540                 dn->dn_nblkptr = 1 +
 541                     ((DN_MAX_BONUSLEN - bonuslen) >> SPA_BLKPTRSHIFT);
 542         dn->dn_bonustype = bonustype;
 543         dn->dn_bonuslen = bonuslen;
 544         dn->dn_checksum = ZIO_CHECKSUM_INHERIT;
 545         dn->dn_compress = ZIO_COMPRESS_INHERIT;
 546         dn->dn_dirtyctx = 0;
 547 
 548         dn->dn_free_txg = 0;
 549         if (dn->dn_dirtyctx_firstset) {
 550                 kmem_free(dn->dn_dirtyctx_firstset, 1);
 551                 dn->dn_dirtyctx_firstset = NULL;
 552         }
 553 
 554         dn->dn_allocated_txg = tx->tx_txg;
 555         dn->dn_id_flags = 0;
 556 
 557         dnode_setdirty(dn, tx);
 558         dn->dn_next_indblkshift[tx->tx_txg & TXG_MASK] = ibs;
 559         dn->dn_next_bonuslen[tx->tx_txg & TXG_MASK] = dn->dn_bonuslen;
 560         dn->dn_next_bonustype[tx->tx_txg & TXG_MASK] = dn->dn_bonustype;
 561         dn->dn_next_blksz[tx->tx_txg & TXG_MASK] = dn->dn_datablksz;
 562 }
 563 
 564 void
 565 dnode_reallocate(dnode_t *dn, dmu_object_type_t ot, int blocksize,
 566     dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
 567 {
 568         int nblkptr;
 569 
 570         ASSERT3U(blocksize, >=, SPA_MINBLOCKSIZE);
 571         ASSERT3U(blocksize, <=, SPA_MAXBLOCKSIZE);
 572         ASSERT0(blocksize % SPA_MINBLOCKSIZE);
 573         ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT || dmu_tx_private_ok(tx));
 574         ASSERT(tx->tx_txg != 0);
 575         ASSERT((bonustype == DMU_OT_NONE && bonuslen == 0) ||
 576             (bonustype != DMU_OT_NONE && bonuslen != 0) ||
 577             (bonustype == DMU_OT_SA && bonuslen == 0));
 578         ASSERT(DMU_OT_IS_VALID(bonustype));
 579         ASSERT3U(bonuslen, <=, DN_MAX_BONUSLEN);
 580 
 581         /* clean up any unreferenced dbufs */
 582         dnode_evict_dbufs(dn);
 583 
 584         dn->dn_id_flags = 0;
 585 
 586         rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
 587         dnode_setdirty(dn, tx);
 588         if (dn->dn_datablksz != blocksize) {
 589                 /* change blocksize */
 590                 ASSERT(dn->dn_maxblkid == 0 &&
 591                     (BP_IS_HOLE(&dn->dn_phys->dn_blkptr[0]) ||
 592                     dnode_block_freed(dn, 0)));
 593                 dnode_setdblksz(dn, blocksize);
 594                 dn->dn_next_blksz[tx->tx_txg&TXG_MASK] = blocksize;
 595         }
 596         if (dn->dn_bonuslen != bonuslen)
 597                 dn->dn_next_bonuslen[tx->tx_txg&TXG_MASK] = bonuslen;
 598 
 599         if (bonustype == DMU_OT_SA) /* Maximize bonus space for SA */
 600                 nblkptr = 1;
 601         else
 602                 nblkptr = 1 + ((DN_MAX_BONUSLEN - bonuslen) >> SPA_BLKPTRSHIFT);
 603         if (dn->dn_bonustype != bonustype)
 604                 dn->dn_next_bonustype[tx->tx_txg&TXG_MASK] = bonustype;
 605         if (dn->dn_nblkptr != nblkptr)
 606                 dn->dn_next_nblkptr[tx->tx_txg&TXG_MASK] = nblkptr;
 607         if (dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
 608                 dbuf_rm_spill(dn, tx);
 609                 dnode_rm_spill(dn, tx);
 610         }
 611         rw_exit(&dn->dn_struct_rwlock);
 612 
 613         /* change type */
 614         dn->dn_type = ot;
 615 
 616         /* change bonus size and type */
 617         mutex_enter(&dn->dn_mtx);
 618         dn->dn_bonustype = bonustype;
 619         dn->dn_bonuslen = bonuslen;
 620         dn->dn_nblkptr = nblkptr;
 621         dn->dn_checksum = ZIO_CHECKSUM_INHERIT;
 622         dn->dn_compress = ZIO_COMPRESS_INHERIT;
 623         ASSERT3U(dn->dn_nblkptr, <=, DN_MAX_NBLKPTR);
 624 
 625         /* fix up the bonus db_size */
 626         if (dn->dn_bonus) {
 627                 dn->dn_bonus->db.db_size =
 628                     DN_MAX_BONUSLEN - (dn->dn_nblkptr-1) * sizeof (blkptr_t);
 629                 ASSERT(dn->dn_bonuslen <= dn->dn_bonus->db.db_size);
 630         }
 631 
 632         dn->dn_allocated_txg = tx->tx_txg;
 633         mutex_exit(&dn->dn_mtx);
 634 }
 635 
 636 #ifdef  DNODE_STATS
 637 static struct {
 638         uint64_t dms_dnode_invalid;
 639         uint64_t dms_dnode_recheck1;
 640         uint64_t dms_dnode_recheck2;
 641         uint64_t dms_dnode_special;
 642         uint64_t dms_dnode_handle;
 643         uint64_t dms_dnode_rwlock;
 644         uint64_t dms_dnode_active;
 645 } dnode_move_stats;
 646 #endif  /* DNODE_STATS */
 647 
 648 static void
 649 dnode_move_impl(dnode_t *odn, dnode_t *ndn)
 650 {
 651         int i;
 652 
 653         ASSERT(!RW_LOCK_HELD(&odn->dn_struct_rwlock));
 654         ASSERT(MUTEX_NOT_HELD(&odn->dn_mtx));
 655         ASSERT(MUTEX_NOT_HELD(&odn->dn_dbufs_mtx));
 656         ASSERT(!RW_LOCK_HELD(&odn->dn_zfetch.zf_rwlock));
 657 
 658         /* Copy fields. */
 659         ndn->dn_objset = odn->dn_objset;
 660         ndn->dn_object = odn->dn_object;
 661         ndn->dn_dbuf = odn->dn_dbuf;
 662         ndn->dn_handle = odn->dn_handle;
 663         ndn->dn_phys = odn->dn_phys;
 664         ndn->dn_type = odn->dn_type;
 665         ndn->dn_bonuslen = odn->dn_bonuslen;
 666         ndn->dn_bonustype = odn->dn_bonustype;
 667         ndn->dn_nblkptr = odn->dn_nblkptr;
 668         ndn->dn_checksum = odn->dn_checksum;
 669         ndn->dn_compress = odn->dn_compress;
 670         ndn->dn_nlevels = odn->dn_nlevels;
 671         ndn->dn_indblkshift = odn->dn_indblkshift;
 672         ndn->dn_datablkshift = odn->dn_datablkshift;
 673         ndn->dn_datablkszsec = odn->dn_datablkszsec;
 674         ndn->dn_datablksz = odn->dn_datablksz;
 675         ndn->dn_maxblkid = odn->dn_maxblkid;
 676         bcopy(&odn->dn_next_nblkptr[0], &ndn->dn_next_nblkptr[0],
 677             sizeof (odn->dn_next_nblkptr));
 678         bcopy(&odn->dn_next_nlevels[0], &ndn->dn_next_nlevels[0],
 679             sizeof (odn->dn_next_nlevels));
 680         bcopy(&odn->dn_next_indblkshift[0], &ndn->dn_next_indblkshift[0],
 681             sizeof (odn->dn_next_indblkshift));
 682         bcopy(&odn->dn_next_bonustype[0], &ndn->dn_next_bonustype[0],
 683             sizeof (odn->dn_next_bonustype));
 684         bcopy(&odn->dn_rm_spillblk[0], &ndn->dn_rm_spillblk[0],
 685             sizeof (odn->dn_rm_spillblk));
 686         bcopy(&odn->dn_next_bonuslen[0], &ndn->dn_next_bonuslen[0],
 687             sizeof (odn->dn_next_bonuslen));
 688         bcopy(&odn->dn_next_blksz[0], &ndn->dn_next_blksz[0],
 689             sizeof (odn->dn_next_blksz));
 690         for (i = 0; i < TXG_SIZE; i++) {
 691                 list_move_tail(&ndn->dn_dirty_records[i],
 692                     &odn->dn_dirty_records[i]);
 693         }
 694         bcopy(&odn->dn_ranges[0], &ndn->dn_ranges[0], sizeof (odn->dn_ranges));
 695         ndn->dn_allocated_txg = odn->dn_allocated_txg;
 696         ndn->dn_free_txg = odn->dn_free_txg;
 697         ndn->dn_assigned_txg = odn->dn_assigned_txg;
 698         ndn->dn_dirtyctx = odn->dn_dirtyctx;
 699         ndn->dn_dirtyctx_firstset = odn->dn_dirtyctx_firstset;
 700         ASSERT(refcount_count(&odn->dn_tx_holds) == 0);
 701         refcount_transfer(&ndn->dn_holds, &odn->dn_holds);
 702         ASSERT(list_is_empty(&ndn->dn_dbufs));
 703         list_move_tail(&ndn->dn_dbufs, &odn->dn_dbufs);
 704         ndn->dn_dbufs_count = odn->dn_dbufs_count;
 705         ndn->dn_bonus = odn->dn_bonus;
 706         ndn->dn_have_spill = odn->dn_have_spill;
 707         ndn->dn_zio = odn->dn_zio;
 708         ndn->dn_oldused = odn->dn_oldused;
 709         ndn->dn_oldflags = odn->dn_oldflags;
 710         ndn->dn_olduid = odn->dn_olduid;
 711         ndn->dn_oldgid = odn->dn_oldgid;
 712         ndn->dn_newuid = odn->dn_newuid;
 713         ndn->dn_newgid = odn->dn_newgid;
 714         ndn->dn_id_flags = odn->dn_id_flags;
 715         dmu_zfetch_init(&ndn->dn_zfetch, NULL);
 716         list_move_tail(&ndn->dn_zfetch.zf_stream, &odn->dn_zfetch.zf_stream);
 717         ndn->dn_zfetch.zf_dnode = odn->dn_zfetch.zf_dnode;
 718         ndn->dn_zfetch.zf_stream_cnt = odn->dn_zfetch.zf_stream_cnt;
 719         ndn->dn_zfetch.zf_alloc_fail = odn->dn_zfetch.zf_alloc_fail;
 720 
 721         /*
 722          * Update back pointers. Updating the handle fixes the back pointer of
 723          * every descendant dbuf as well as the bonus dbuf.
 724          */
 725         ASSERT(ndn->dn_handle->dnh_dnode == odn);
 726         ndn->dn_handle->dnh_dnode = ndn;
 727         if (ndn->dn_zfetch.zf_dnode == odn) {
 728                 ndn->dn_zfetch.zf_dnode = ndn;
 729         }
 730 
 731         /*
 732          * Invalidate the original dnode by clearing all of its back pointers.
 733          */
 734         odn->dn_dbuf = NULL;
 735         odn->dn_handle = NULL;
 736         list_create(&odn->dn_dbufs, sizeof (dmu_buf_impl_t),
 737             offsetof(dmu_buf_impl_t, db_link));
 738         odn->dn_dbufs_count = 0;
 739         odn->dn_bonus = NULL;
 740         odn->dn_zfetch.zf_dnode = NULL;
 741 
 742         /*
 743          * Set the low bit of the objset pointer to ensure that dnode_move()
 744          * recognizes the dnode as invalid in any subsequent callback.
 745          */
 746         POINTER_INVALIDATE(&odn->dn_objset);
 747 
 748         /*
 749          * Satisfy the destructor.
 750          */
 751         for (i = 0; i < TXG_SIZE; i++) {
 752                 list_create(&odn->dn_dirty_records[i],
 753                     sizeof (dbuf_dirty_record_t),
 754                     offsetof(dbuf_dirty_record_t, dr_dirty_node));
 755                 odn->dn_ranges[i].avl_root = NULL;
 756                 odn->dn_ranges[i].avl_numnodes = 0;
 757                 odn->dn_next_nlevels[i] = 0;
 758                 odn->dn_next_indblkshift[i] = 0;
 759                 odn->dn_next_bonustype[i] = 0;
 760                 odn->dn_rm_spillblk[i] = 0;
 761                 odn->dn_next_bonuslen[i] = 0;
 762                 odn->dn_next_blksz[i] = 0;
 763         }
 764         odn->dn_allocated_txg = 0;
 765         odn->dn_free_txg = 0;
 766         odn->dn_assigned_txg = 0;
 767         odn->dn_dirtyctx = 0;
 768         odn->dn_dirtyctx_firstset = NULL;
 769         odn->dn_have_spill = B_FALSE;
 770         odn->dn_zio = NULL;
 771         odn->dn_oldused = 0;
 772         odn->dn_oldflags = 0;
 773         odn->dn_olduid = 0;
 774         odn->dn_oldgid = 0;
 775         odn->dn_newuid = 0;
 776         odn->dn_newgid = 0;
 777         odn->dn_id_flags = 0;
 778 
 779         /*
 780          * Mark the dnode.
 781          */
 782         ndn->dn_moved = 1;
 783         odn->dn_moved = (uint8_t)-1;
 784 }
 785 
 786 #ifdef  _KERNEL
 787 /*ARGSUSED*/
 788 static kmem_cbrc_t
 789 dnode_move(void *buf, void *newbuf, size_t size, void *arg)
 790 {
 791         dnode_t *odn = buf, *ndn = newbuf;
 792         objset_t *os;
 793         int64_t refcount;
 794         uint32_t dbufs;
 795 
 796         /*
 797          * The dnode is on the objset's list of known dnodes if the objset
 798          * pointer is valid. We set the low bit of the objset pointer when
 799          * freeing the dnode to invalidate it, and the memory patterns written
 800          * by kmem (baddcafe and deadbeef) set at least one of the two low bits.
 801          * A newly created dnode sets the objset pointer last of all to indicate
 802          * that the dnode is known and in a valid state to be moved by this
 803          * function.
 804          */
 805         os = odn->dn_objset;
 806         if (!POINTER_IS_VALID(os)) {
 807                 DNODE_STAT_ADD(dnode_move_stats.dms_dnode_invalid);
 808                 return (KMEM_CBRC_DONT_KNOW);
 809         }
 810 
 811         /*
 812          * Ensure that the objset does not go away during the move.
 813          */
 814         rw_enter(&os_lock, RW_WRITER);
 815         if (os != odn->dn_objset) {
 816                 rw_exit(&os_lock);
 817                 DNODE_STAT_ADD(dnode_move_stats.dms_dnode_recheck1);
 818                 return (KMEM_CBRC_DONT_KNOW);
 819         }
 820 
 821         /*
 822          * If the dnode is still valid, then so is the objset. We know that no
 823          * valid objset can be freed while we hold os_lock, so we can safely
 824          * ensure that the objset remains in use.
 825          */
 826         mutex_enter(&os->os_lock);
 827 
 828         /*
 829          * Recheck the objset pointer in case the dnode was removed just before
 830          * acquiring the lock.
 831          */
 832         if (os != odn->dn_objset) {
 833                 mutex_exit(&os->os_lock);
 834                 rw_exit(&os_lock);
 835                 DNODE_STAT_ADD(dnode_move_stats.dms_dnode_recheck2);
 836                 return (KMEM_CBRC_DONT_KNOW);
 837         }
 838 
 839         /*
 840          * At this point we know that as long as we hold os->os_lock, the dnode
 841          * cannot be freed and fields within the dnode can be safely accessed.
 842          * The objset listing this dnode cannot go away as long as this dnode is
 843          * on its list.
 844          */
 845         rw_exit(&os_lock);
 846         if (DMU_OBJECT_IS_SPECIAL(odn->dn_object)) {
 847                 mutex_exit(&os->os_lock);
 848                 DNODE_STAT_ADD(dnode_move_stats.dms_dnode_special);
 849                 return (KMEM_CBRC_NO);
 850         }
 851         ASSERT(odn->dn_dbuf != NULL); /* only "special" dnodes have no parent */
 852 
 853         /*
 854          * Lock the dnode handle to prevent the dnode from obtaining any new
 855          * holds. This also prevents the descendant dbufs and the bonus dbuf
 856          * from accessing the dnode, so that we can discount their holds. The
 857          * handle is safe to access because we know that while the dnode cannot
 858          * go away, neither can its handle. Once we hold dnh_zrlock, we can
 859          * safely move any dnode referenced only by dbufs.
 860          */
 861         if (!zrl_tryenter(&odn->dn_handle->dnh_zrlock)) {
 862                 mutex_exit(&os->os_lock);
 863                 DNODE_STAT_ADD(dnode_move_stats.dms_dnode_handle);
 864                 return (KMEM_CBRC_LATER);
 865         }
 866 
 867         /*
 868          * Ensure a consistent view of the dnode's holds and the dnode's dbufs.
 869          * We need to guarantee that there is a hold for every dbuf in order to
 870          * determine whether the dnode is actively referenced. Falsely matching
 871          * a dbuf to an active hold would lead to an unsafe move. It's possible
 872          * that a thread already having an active dnode hold is about to add a
 873          * dbuf, and we can't compare hold and dbuf counts while the add is in
 874          * progress.
 875          */
 876         if (!rw_tryenter(&odn->dn_struct_rwlock, RW_WRITER)) {
 877                 zrl_exit(&odn->dn_handle->dnh_zrlock);
 878                 mutex_exit(&os->os_lock);
 879                 DNODE_STAT_ADD(dnode_move_stats.dms_dnode_rwlock);
 880                 return (KMEM_CBRC_LATER);
 881         }
 882 
 883         /*
 884          * A dbuf may be removed (evicted) without an active dnode hold. In that
 885          * case, the dbuf count is decremented under the handle lock before the
 886          * dbuf's hold is released. This order ensures that if we count the hold
 887          * after the dbuf is removed but before its hold is released, we will
 888          * treat the unmatched hold as active and exit safely. If we count the
 889          * hold before the dbuf is removed, the hold is discounted, and the
 890          * removal is blocked until the move completes.
 891          */
 892         refcount = refcount_count(&odn->dn_holds);
 893         ASSERT(refcount >= 0);
 894         dbufs = odn->dn_dbufs_count;
 895 
 896         /* We can't have more dbufs than dnode holds. */
 897         ASSERT3U(dbufs, <=, refcount);
 898         DTRACE_PROBE3(dnode__move, dnode_t *, odn, int64_t, refcount,
 899             uint32_t, dbufs);
 900 
 901         if (refcount > dbufs) {
 902                 rw_exit(&odn->dn_struct_rwlock);
 903                 zrl_exit(&odn->dn_handle->dnh_zrlock);
 904                 mutex_exit(&os->os_lock);
 905                 DNODE_STAT_ADD(dnode_move_stats.dms_dnode_active);
 906                 return (KMEM_CBRC_LATER);
 907         }
 908 
 909         rw_exit(&odn->dn_struct_rwlock);
 910 
 911         /*
 912          * At this point we know that anyone with a hold on the dnode is not
 913          * actively referencing it. The dnode is known and in a valid state to
 914          * move. We're holding the locks needed to execute the critical section.
 915          */
 916         dnode_move_impl(odn, ndn);
 917 
 918         list_link_replace(&odn->dn_link, &ndn->dn_link);
 919         /* If the dnode was safe to move, the refcount cannot have changed. */
 920         ASSERT(refcount == refcount_count(&ndn->dn_holds));
 921         ASSERT(dbufs == ndn->dn_dbufs_count);
 922         zrl_exit(&ndn->dn_handle->dnh_zrlock); /* handle has moved */
 923         mutex_exit(&os->os_lock);
 924 
 925         return (KMEM_CBRC_YES);
 926 }
 927 #endif  /* _KERNEL */
 928 
 929 void
 930 dnode_special_close(dnode_handle_t *dnh)
 931 {
 932         dnode_t *dn = dnh->dnh_dnode;
 933 
 934         /*
 935          * Wait for final references to the dnode to clear.  This can
 936          * only happen if the arc is asyncronously evicting state that
 937          * has a hold on this dnode while we are trying to evict this
 938          * dnode.
 939          */
 940         while (refcount_count(&dn->dn_holds) > 0)
 941                 delay(1);
 942         zrl_add(&dnh->dnh_zrlock);
 943         dnode_destroy(dn); /* implicit zrl_remove() */
 944         zrl_destroy(&dnh->dnh_zrlock);
 945         dnh->dnh_dnode = NULL;
 946 }
 947 
 948 dnode_t *
 949 dnode_special_open(objset_t *os, dnode_phys_t *dnp, uint64_t object,
 950     dnode_handle_t *dnh)
 951 {
 952         dnode_t *dn = dnode_create(os, dnp, NULL, object, dnh);
 953         dnh->dnh_dnode = dn;
 954         zrl_init(&dnh->dnh_zrlock);
 955         DNODE_VERIFY(dn);
 956         return (dn);
 957 }
 958 
 959 static void
 960 dnode_buf_pageout(dmu_buf_t *db, void *arg)
 961 {
 962         dnode_children_t *children_dnodes = arg;
 963         int i;
 964         int epb = db->db_size >> DNODE_SHIFT;
 965 
 966         ASSERT(epb == children_dnodes->dnc_count);
 967 
 968         for (i = 0; i < epb; i++) {
 969                 dnode_handle_t *dnh = &children_dnodes->dnc_children[i];
 970                 dnode_t *dn;
 971 
 972                 /*
 973                  * The dnode handle lock guards against the dnode moving to
 974                  * another valid address, so there is no need here to guard
 975                  * against changes to or from NULL.
 976                  */
 977                 if (dnh->dnh_dnode == NULL) {
 978                         zrl_destroy(&dnh->dnh_zrlock);
 979                         continue;
 980                 }
 981 
 982                 zrl_add(&dnh->dnh_zrlock);
 983                 dn = dnh->dnh_dnode;
 984                 /*
 985                  * If there are holds on this dnode, then there should
 986                  * be holds on the dnode's containing dbuf as well; thus
 987                  * it wouldn't be eligible for eviction and this function
 988                  * would not have been called.
 989                  */
 990                 ASSERT(refcount_is_zero(&dn->dn_holds));
 991                 ASSERT(refcount_is_zero(&dn->dn_tx_holds));
 992 
 993                 dnode_destroy(dn); /* implicit zrl_remove() */
 994                 zrl_destroy(&dnh->dnh_zrlock);
 995                 dnh->dnh_dnode = NULL;
 996         }
 997         kmem_free(children_dnodes, sizeof (dnode_children_t) +
 998             (epb - 1) * sizeof (dnode_handle_t));
 999 }
1000 
1001 /*
1002  * errors:
1003  * EINVAL - invalid object number.
1004  * EIO - i/o error.
1005  * succeeds even for free dnodes.
1006  */
1007 int
1008 dnode_hold_impl(objset_t *os, uint64_t object, int flag,
1009     void *tag, dnode_t **dnp)
1010 {
1011         int epb, idx, err;
1012         int drop_struct_lock = FALSE;
1013         int type;
1014         uint64_t blk;
1015         dnode_t *mdn, *dn;
1016         dmu_buf_impl_t *db;
1017         dnode_children_t *children_dnodes;
1018         dnode_handle_t *dnh;
1019 
1020         /*
1021          * If you are holding the spa config lock as writer, you shouldn't
1022          * be asking the DMU to do *anything* unless it's the root pool
1023          * which may require us to read from the root filesystem while
1024          * holding some (not all) of the locks as writer.
1025          */
1026         ASSERT(spa_config_held(os->os_spa, SCL_ALL, RW_WRITER) == 0 ||
1027             (spa_is_root(os->os_spa) &&
1028             spa_config_held(os->os_spa, SCL_STATE, RW_WRITER)));
1029 
1030         if (object == DMU_USERUSED_OBJECT || object == DMU_GROUPUSED_OBJECT) {
1031                 dn = (object == DMU_USERUSED_OBJECT) ?
1032                     DMU_USERUSED_DNODE(os) : DMU_GROUPUSED_DNODE(os);
1033                 if (dn == NULL)
1034                         return (SET_ERROR(ENOENT));
1035                 type = dn->dn_type;
1036                 if ((flag & DNODE_MUST_BE_ALLOCATED) && type == DMU_OT_NONE)
1037                         return (SET_ERROR(ENOENT));
1038                 if ((flag & DNODE_MUST_BE_FREE) && type != DMU_OT_NONE)
1039                         return (SET_ERROR(EEXIST));
1040                 DNODE_VERIFY(dn);
1041                 (void) refcount_add(&dn->dn_holds, tag);
1042                 *dnp = dn;
1043                 return (0);
1044         }
1045 
1046         if (object == 0 || object >= DN_MAX_OBJECT)
1047                 return (SET_ERROR(EINVAL));
1048 
1049         mdn = DMU_META_DNODE(os);
1050         ASSERT(mdn->dn_object == DMU_META_DNODE_OBJECT);
1051 
1052         DNODE_VERIFY(mdn);
1053 
1054         if (!RW_WRITE_HELD(&mdn->dn_struct_rwlock)) {
1055                 rw_enter(&mdn->dn_struct_rwlock, RW_READER);
1056                 drop_struct_lock = TRUE;
1057         }
1058 
1059         blk = dbuf_whichblock(mdn, object * sizeof (dnode_phys_t));
1060 
1061         db = dbuf_hold(mdn, blk, FTAG);
1062         if (drop_struct_lock)
1063                 rw_exit(&mdn->dn_struct_rwlock);
1064         if (db == NULL)
1065                 return (SET_ERROR(EIO));
1066         err = dbuf_read(db, NULL, DB_RF_CANFAIL);
1067         if (err) {
1068                 dbuf_rele(db, FTAG);
1069                 return (err);
1070         }
1071 
1072         ASSERT3U(db->db.db_size, >=, 1<<DNODE_SHIFT);
1073         epb = db->db.db_size >> DNODE_SHIFT;
1074 
1075         idx = object & (epb-1);
1076 
1077         ASSERT(DB_DNODE(db)->dn_type == DMU_OT_DNODE);
1078         children_dnodes = dmu_buf_get_user(&db->db);
1079         if (children_dnodes == NULL) {
1080                 int i;
1081                 dnode_children_t *winner;
1082                 children_dnodes = kmem_alloc(sizeof (dnode_children_t) +
1083                     (epb - 1) * sizeof (dnode_handle_t), KM_SLEEP);
1084                 children_dnodes->dnc_count = epb;
1085                 dnh = &children_dnodes->dnc_children[0];
1086                 for (i = 0; i < epb; i++) {
1087                         zrl_init(&dnh[i].dnh_zrlock);
1088                         dnh[i].dnh_dnode = NULL;
1089                 }
1090                 if (winner = dmu_buf_set_user(&db->db, children_dnodes, NULL,
1091                     dnode_buf_pageout)) {
1092                         kmem_free(children_dnodes, sizeof (dnode_children_t) +
1093                             (epb - 1) * sizeof (dnode_handle_t));
1094                         children_dnodes = winner;
1095                 }
1096         }
1097         ASSERT(children_dnodes->dnc_count == epb);
1098 
1099         dnh = &children_dnodes->dnc_children[idx];
1100         zrl_add(&dnh->dnh_zrlock);
1101         if ((dn = dnh->dnh_dnode) == NULL) {
1102                 dnode_phys_t *phys = (dnode_phys_t *)db->db.db_data+idx;
1103                 dnode_t *winner;
1104 
1105                 dn = dnode_create(os, phys, db, object, dnh);
1106                 winner = atomic_cas_ptr(&dnh->dnh_dnode, NULL, dn);
1107                 if (winner != NULL) {
1108                         zrl_add(&dnh->dnh_zrlock);
1109                         dnode_destroy(dn); /* implicit zrl_remove() */
1110                         dn = winner;
1111                 }
1112         }
1113 
1114         mutex_enter(&dn->dn_mtx);
1115         type = dn->dn_type;
1116         if (dn->dn_free_txg ||
1117             ((flag & DNODE_MUST_BE_ALLOCATED) && type == DMU_OT_NONE) ||
1118             ((flag & DNODE_MUST_BE_FREE) &&
1119             (type != DMU_OT_NONE || !refcount_is_zero(&dn->dn_holds)))) {
1120                 mutex_exit(&dn->dn_mtx);
1121                 zrl_remove(&dnh->dnh_zrlock);
1122                 dbuf_rele(db, FTAG);
1123                 return (type == DMU_OT_NONE ? ENOENT : EEXIST);
1124         }
1125         mutex_exit(&dn->dn_mtx);
1126 
1127         if (refcount_add(&dn->dn_holds, tag) == 1)
1128                 dbuf_add_ref(db, dnh);
1129         /* Now we can rely on the hold to prevent the dnode from moving. */
1130         zrl_remove(&dnh->dnh_zrlock);
1131 
1132         DNODE_VERIFY(dn);
1133         ASSERT3P(dn->dn_dbuf, ==, db);
1134         ASSERT3U(dn->dn_object, ==, object);
1135         dbuf_rele(db, FTAG);
1136 
1137         *dnp = dn;
1138         return (0);
1139 }
1140 
1141 /*
1142  * Return held dnode if the object is allocated, NULL if not.
1143  */
1144 int
1145 dnode_hold(objset_t *os, uint64_t object, void *tag, dnode_t **dnp)
1146 {
1147         return (dnode_hold_impl(os, object, DNODE_MUST_BE_ALLOCATED, tag, dnp));
1148 }
1149 
1150 /*
1151  * Can only add a reference if there is already at least one
1152  * reference on the dnode.  Returns FALSE if unable to add a
1153  * new reference.
1154  */
1155 boolean_t
1156 dnode_add_ref(dnode_t *dn, void *tag)
1157 {
1158         mutex_enter(&dn->dn_mtx);
1159         if (refcount_is_zero(&dn->dn_holds)) {
1160                 mutex_exit(&dn->dn_mtx);
1161                 return (FALSE);
1162         }
1163         VERIFY(1 < refcount_add(&dn->dn_holds, tag));
1164         mutex_exit(&dn->dn_mtx);
1165         return (TRUE);
1166 }
1167 
1168 void
1169 dnode_rele(dnode_t *dn, void *tag)
1170 {
1171         uint64_t refs;
1172         /* Get while the hold prevents the dnode from moving. */
1173         dmu_buf_impl_t *db = dn->dn_dbuf;
1174         dnode_handle_t *dnh = dn->dn_handle;
1175 
1176         mutex_enter(&dn->dn_mtx);
1177         refs = refcount_remove(&dn->dn_holds, tag);
1178         mutex_exit(&dn->dn_mtx);
1179 
1180         /*
1181          * It's unsafe to release the last hold on a dnode by dnode_rele() or
1182          * indirectly by dbuf_rele() while relying on the dnode handle to
1183          * prevent the dnode from moving, since releasing the last hold could
1184          * result in the dnode's parent dbuf evicting its dnode handles. For
1185          * that reason anyone calling dnode_rele() or dbuf_rele() without some
1186          * other direct or indirect hold on the dnode must first drop the dnode
1187          * handle.
1188          */
1189         ASSERT(refs > 0 || dnh->dnh_zrlock.zr_owner != curthread);
1190 
1191         /* NOTE: the DNODE_DNODE does not have a dn_dbuf */
1192         if (refs == 0 && db != NULL) {
1193                 /*
1194                  * Another thread could add a hold to the dnode handle in
1195                  * dnode_hold_impl() while holding the parent dbuf. Since the
1196                  * hold on the parent dbuf prevents the handle from being
1197                  * destroyed, the hold on the handle is OK. We can't yet assert
1198                  * that the handle has zero references, but that will be
1199                  * asserted anyway when the handle gets destroyed.
1200                  */
1201                 dbuf_rele(db, dnh);
1202         }
1203 }
1204 
1205 void
1206 dnode_setdirty(dnode_t *dn, dmu_tx_t *tx)
1207 {
1208         objset_t *os = dn->dn_objset;
1209         uint64_t txg = tx->tx_txg;
1210 
1211         if (DMU_OBJECT_IS_SPECIAL(dn->dn_object)) {
1212                 dsl_dataset_dirty(os->os_dsl_dataset, tx);
1213                 return;
1214         }
1215 
1216         DNODE_VERIFY(dn);
1217 
1218 #ifdef ZFS_DEBUG
1219         mutex_enter(&dn->dn_mtx);
1220         ASSERT(dn->dn_phys->dn_type || dn->dn_allocated_txg);
1221         ASSERT(dn->dn_free_txg == 0 || dn->dn_free_txg >= txg);
1222         mutex_exit(&dn->dn_mtx);
1223 #endif
1224 
1225         /*
1226          * Determine old uid/gid when necessary
1227          */
1228         dmu_objset_userquota_get_ids(dn, B_TRUE, tx);
1229 
1230         mutex_enter(&os->os_lock);
1231 
1232         /*
1233          * If we are already marked dirty, we're done.
1234          */
1235         if (list_link_active(&dn->dn_dirty_link[txg & TXG_MASK])) {
1236                 mutex_exit(&os->os_lock);
1237                 return;
1238         }
1239 
1240         ASSERT(!refcount_is_zero(&dn->dn_holds) || list_head(&dn->dn_dbufs));
1241         ASSERT(dn->dn_datablksz != 0);
1242         ASSERT0(dn->dn_next_bonuslen[txg&TXG_MASK]);
1243         ASSERT0(dn->dn_next_blksz[txg&TXG_MASK]);
1244         ASSERT0(dn->dn_next_bonustype[txg&TXG_MASK]);
1245 
1246         dprintf_ds(os->os_dsl_dataset, "obj=%llu txg=%llu\n",
1247             dn->dn_object, txg);
1248 
1249         if (dn->dn_free_txg > 0 && dn->dn_free_txg <= txg) {
1250                 list_insert_tail(&os->os_free_dnodes[txg&TXG_MASK], dn);
1251         } else {
1252                 list_insert_tail(&os->os_dirty_dnodes[txg&TXG_MASK], dn);
1253         }
1254 
1255         mutex_exit(&os->os_lock);
1256 
1257         /*
1258          * The dnode maintains a hold on its containing dbuf as
1259          * long as there are holds on it.  Each instantiated child
1260          * dbuf maintains a hold on the dnode.  When the last child
1261          * drops its hold, the dnode will drop its hold on the
1262          * containing dbuf. We add a "dirty hold" here so that the
1263          * dnode will hang around after we finish processing its
1264          * children.
1265          */
1266         VERIFY(dnode_add_ref(dn, (void *)(uintptr_t)tx->tx_txg));
1267 
1268         (void) dbuf_dirty(dn->dn_dbuf, tx);
1269 
1270         dsl_dataset_dirty(os->os_dsl_dataset, tx);
1271 }
1272 
1273 void
1274 dnode_free(dnode_t *dn, dmu_tx_t *tx)
1275 {
1276         int txgoff = tx->tx_txg & TXG_MASK;
1277 
1278         dprintf("dn=%p txg=%llu\n", dn, tx->tx_txg);
1279 
1280         /* we should be the only holder... hopefully */
1281         /* ASSERT3U(refcount_count(&dn->dn_holds), ==, 1); */
1282 
1283         mutex_enter(&dn->dn_mtx);
1284         if (dn->dn_type == DMU_OT_NONE || dn->dn_free_txg) {
1285                 mutex_exit(&dn->dn_mtx);
1286                 return;
1287         }
1288         dn->dn_free_txg = tx->tx_txg;
1289         mutex_exit(&dn->dn_mtx);
1290 
1291         /*
1292          * If the dnode is already dirty, it needs to be moved from
1293          * the dirty list to the free list.
1294          */
1295         mutex_enter(&dn->dn_objset->os_lock);
1296         if (list_link_active(&dn->dn_dirty_link[txgoff])) {
1297                 list_remove(&dn->dn_objset->os_dirty_dnodes[txgoff], dn);
1298                 list_insert_tail(&dn->dn_objset->os_free_dnodes[txgoff], dn);
1299                 mutex_exit(&dn->dn_objset->os_lock);
1300         } else {
1301                 mutex_exit(&dn->dn_objset->os_lock);
1302                 dnode_setdirty(dn, tx);
1303         }
1304 }
1305 
1306 /*
1307  * Try to change the block size for the indicated dnode.  This can only
1308  * succeed if there are no blocks allocated or dirty beyond first block
1309  */
1310 int
1311 dnode_set_blksz(dnode_t *dn, uint64_t size, int ibs, dmu_tx_t *tx)
1312 {
1313         dmu_buf_impl_t *db, *db_next;
1314         int err;
1315 
1316         if (size == 0)
1317                 size = SPA_MINBLOCKSIZE;
1318         if (size > SPA_MAXBLOCKSIZE)
1319                 size = SPA_MAXBLOCKSIZE;
1320         else
1321                 size = P2ROUNDUP(size, SPA_MINBLOCKSIZE);
1322 
1323         if (ibs == dn->dn_indblkshift)
1324                 ibs = 0;
1325 
1326         if (size >> SPA_MINBLOCKSHIFT == dn->dn_datablkszsec && ibs == 0)
1327                 return (0);
1328 
1329         rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
1330 
1331         /* Check for any allocated blocks beyond the first */
1332         if (dn->dn_phys->dn_maxblkid != 0)
1333                 goto fail;
1334 
1335         mutex_enter(&dn->dn_dbufs_mtx);
1336         for (db = list_head(&dn->dn_dbufs); db; db = db_next) {
1337                 db_next = list_next(&dn->dn_dbufs, db);
1338 
1339                 if (db->db_blkid != 0 && db->db_blkid != DMU_BONUS_BLKID &&
1340                     db->db_blkid != DMU_SPILL_BLKID) {
1341                         mutex_exit(&dn->dn_dbufs_mtx);
1342                         goto fail;
1343                 }
1344         }
1345         mutex_exit(&dn->dn_dbufs_mtx);
1346 
1347         if (ibs && dn->dn_nlevels != 1)
1348                 goto fail;
1349 
1350         /* resize the old block */
1351         err = dbuf_hold_impl(dn, 0, 0, TRUE, FTAG, &db);
1352         if (err == 0)
1353                 dbuf_new_size(db, size, tx);
1354         else if (err != ENOENT)
1355                 goto fail;
1356 
1357         dnode_setdblksz(dn, size);
1358         dnode_setdirty(dn, tx);
1359         dn->dn_next_blksz[tx->tx_txg&TXG_MASK] = size;
1360         if (ibs) {
1361                 dn->dn_indblkshift = ibs;
1362                 dn->dn_next_indblkshift[tx->tx_txg&TXG_MASK] = ibs;
1363         }
1364         /* rele after we have fixed the blocksize in the dnode */
1365         if (db)
1366                 dbuf_rele(db, FTAG);
1367 
1368         rw_exit(&dn->dn_struct_rwlock);
1369         return (0);
1370 
1371 fail:
1372         rw_exit(&dn->dn_struct_rwlock);
1373         return (SET_ERROR(ENOTSUP));
1374 }
1375 
1376 /* read-holding callers must not rely on the lock being continuously held */
1377 void
1378 dnode_new_blkid(dnode_t *dn, uint64_t blkid, dmu_tx_t *tx, boolean_t have_read)
1379 {
1380         uint64_t txgoff = tx->tx_txg & TXG_MASK;
1381         int epbs, new_nlevels;
1382         uint64_t sz;
1383 
1384         ASSERT(blkid != DMU_BONUS_BLKID);
1385 
1386         ASSERT(have_read ?
1387             RW_READ_HELD(&dn->dn_struct_rwlock) :
1388             RW_WRITE_HELD(&dn->dn_struct_rwlock));
1389 
1390         /*
1391          * if we have a read-lock, check to see if we need to do any work
1392          * before upgrading to a write-lock.
1393          */
1394         if (have_read) {
1395                 if (blkid <= dn->dn_maxblkid)
1396                         return;
1397 
1398                 if (!rw_tryupgrade(&dn->dn_struct_rwlock)) {
1399                         rw_exit(&dn->dn_struct_rwlock);
1400                         rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
1401                 }
1402         }
1403 
1404         if (blkid <= dn->dn_maxblkid)
1405                 goto out;
1406 
1407         dn->dn_maxblkid = blkid;
1408 
1409         /*
1410          * Compute the number of levels necessary to support the new maxblkid.
1411          */
1412         new_nlevels = 1;
1413         epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1414         for (sz = dn->dn_nblkptr;
1415             sz <= blkid && sz >= dn->dn_nblkptr; sz <<= epbs)
1416                 new_nlevels++;
1417 
1418         if (new_nlevels > dn->dn_nlevels) {
1419                 int old_nlevels = dn->dn_nlevels;
1420                 dmu_buf_impl_t *db;
1421                 list_t *list;
1422                 dbuf_dirty_record_t *new, *dr, *dr_next;
1423 
1424                 dn->dn_nlevels = new_nlevels;
1425 
1426                 ASSERT3U(new_nlevels, >, dn->dn_next_nlevels[txgoff]);
1427                 dn->dn_next_nlevels[txgoff] = new_nlevels;
1428 
1429                 /* dirty the left indirects */
1430                 db = dbuf_hold_level(dn, old_nlevels, 0, FTAG);
1431                 ASSERT(db != NULL);
1432                 new = dbuf_dirty(db, tx);
1433                 dbuf_rele(db, FTAG);
1434 
1435                 /* transfer the dirty records to the new indirect */
1436                 mutex_enter(&dn->dn_mtx);
1437                 mutex_enter(&new->dt.di.dr_mtx);
1438                 list = &dn->dn_dirty_records[txgoff];
1439                 for (dr = list_head(list); dr; dr = dr_next) {
1440                         dr_next = list_next(&dn->dn_dirty_records[txgoff], dr);
1441                         if (dr->dr_dbuf->db_level != new_nlevels-1 &&
1442                             dr->dr_dbuf->db_blkid != DMU_BONUS_BLKID &&
1443                             dr->dr_dbuf->db_blkid != DMU_SPILL_BLKID) {
1444                                 ASSERT(dr->dr_dbuf->db_level == old_nlevels-1);
1445                                 list_remove(&dn->dn_dirty_records[txgoff], dr);
1446                                 list_insert_tail(&new->dt.di.dr_children, dr);
1447                                 dr->dr_parent = new;
1448                         }
1449                 }
1450                 mutex_exit(&new->dt.di.dr_mtx);
1451                 mutex_exit(&dn->dn_mtx);
1452         }
1453 
1454 out:
1455         if (have_read)
1456                 rw_downgrade(&dn->dn_struct_rwlock);
1457 }
1458 
1459 void
1460 dnode_clear_range(dnode_t *dn, uint64_t blkid, uint64_t nblks, dmu_tx_t *tx)
1461 {
1462         avl_tree_t *tree = &dn->dn_ranges[tx->tx_txg&TXG_MASK];
1463         avl_index_t where;
1464         free_range_t *rp;
1465         free_range_t rp_tofind;
1466         uint64_t endblk = blkid + nblks;
1467 
1468         ASSERT(MUTEX_HELD(&dn->dn_mtx));
1469         ASSERT(nblks <= UINT64_MAX - blkid); /* no overflow */
1470 
1471         dprintf_dnode(dn, "blkid=%llu nblks=%llu txg=%llu\n",
1472             blkid, nblks, tx->tx_txg);
1473         rp_tofind.fr_blkid = blkid;
1474         rp = avl_find(tree, &rp_tofind, &where);
1475         if (rp == NULL)
1476                 rp = avl_nearest(tree, where, AVL_BEFORE);
1477         if (rp == NULL)
1478                 rp = avl_nearest(tree, where, AVL_AFTER);
1479 
1480         while (rp && (rp->fr_blkid <= blkid + nblks)) {
1481                 uint64_t fr_endblk = rp->fr_blkid + rp->fr_nblks;
1482                 free_range_t *nrp = AVL_NEXT(tree, rp);
1483 
1484                 if (blkid <= rp->fr_blkid && endblk >= fr_endblk) {
1485                         /* clear this entire range */
1486                         avl_remove(tree, rp);
1487                         kmem_free(rp, sizeof (free_range_t));
1488                 } else if (blkid <= rp->fr_blkid &&
1489                     endblk > rp->fr_blkid && endblk < fr_endblk) {
1490                         /* clear the beginning of this range */
1491                         rp->fr_blkid = endblk;
1492                         rp->fr_nblks = fr_endblk - endblk;
1493                 } else if (blkid > rp->fr_blkid && blkid < fr_endblk &&
1494                     endblk >= fr_endblk) {
1495                         /* clear the end of this range */
1496                         rp->fr_nblks = blkid - rp->fr_blkid;
1497                 } else if (blkid > rp->fr_blkid && endblk < fr_endblk) {
1498                         /* clear a chunk out of this range */
1499                         free_range_t *new_rp =
1500                             kmem_alloc(sizeof (free_range_t), KM_SLEEP);
1501 
1502                         new_rp->fr_blkid = endblk;
1503                         new_rp->fr_nblks = fr_endblk - endblk;
1504                         avl_insert_here(tree, new_rp, rp, AVL_AFTER);
1505                         rp->fr_nblks = blkid - rp->fr_blkid;
1506                 }
1507                 /* there may be no overlap */
1508                 rp = nrp;
1509         }
1510 }
1511 
1512 void
1513 dnode_free_range(dnode_t *dn, uint64_t off, uint64_t len, dmu_tx_t *tx)
1514 {
1515         dmu_buf_impl_t *db;
1516         uint64_t blkoff, blkid, nblks;
1517         int blksz, blkshift, head, tail;
1518         int trunc = FALSE;
1519         int epbs;
1520 
1521         rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
1522         blksz = dn->dn_datablksz;
1523         blkshift = dn->dn_datablkshift;
1524         epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1525 
1526         if (len == -1ULL) {
1527                 len = UINT64_MAX - off;
1528                 trunc = TRUE;
1529         }
1530 
1531         /*
1532          * First, block align the region to free:
1533          */
1534         if (ISP2(blksz)) {
1535                 head = P2NPHASE(off, blksz);
1536                 blkoff = P2PHASE(off, blksz);
1537                 if ((off >> blkshift) > dn->dn_maxblkid)
1538                         goto out;
1539         } else {
1540                 ASSERT(dn->dn_maxblkid == 0);
1541                 if (off == 0 && len >= blksz) {
1542                         /* Freeing the whole block; fast-track this request */
1543                         blkid = 0;
1544                         nblks = 1;
1545                         goto done;
1546                 } else if (off >= blksz) {
1547                         /* Freeing past end-of-data */
1548                         goto out;
1549                 } else {
1550                         /* Freeing part of the block. */
1551                         head = blksz - off;
1552                         ASSERT3U(head, >, 0);
1553                 }
1554                 blkoff = off;
1555         }
1556         /* zero out any partial block data at the start of the range */
1557         if (head) {
1558                 ASSERT3U(blkoff + head, ==, blksz);
1559                 if (len < head)
1560                         head = len;
1561                 if (dbuf_hold_impl(dn, 0, dbuf_whichblock(dn, off), TRUE,
1562                     FTAG, &db) == 0) {
1563                         caddr_t data;
1564 
1565                         /* don't dirty if it isn't on disk and isn't dirty */
1566                         if (db->db_last_dirty ||
1567                             (db->db_blkptr && !BP_IS_HOLE(db->db_blkptr))) {
1568                                 rw_exit(&dn->dn_struct_rwlock);
1569                                 dbuf_will_dirty(db, tx);
1570                                 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
1571                                 data = db->db.db_data;
1572                                 bzero(data + blkoff, head);
1573                         }
1574                         dbuf_rele(db, FTAG);
1575                 }
1576                 off += head;
1577                 len -= head;
1578         }
1579 
1580         /* If the range was less than one block, we're done */
1581         if (len == 0)
1582                 goto out;
1583 
1584         /* If the remaining range is past end of file, we're done */
1585         if ((off >> blkshift) > dn->dn_maxblkid)
1586                 goto out;
1587 
1588         ASSERT(ISP2(blksz));
1589         if (trunc)
1590                 tail = 0;
1591         else
1592                 tail = P2PHASE(len, blksz);
1593 
1594         ASSERT0(P2PHASE(off, blksz));
1595         /* zero out any partial block data at the end of the range */
1596         if (tail) {
1597                 if (len < tail)
1598                         tail = len;
1599                 if (dbuf_hold_impl(dn, 0, dbuf_whichblock(dn, off+len),
1600                     TRUE, FTAG, &db) == 0) {
1601                         /* don't dirty if not on disk and not dirty */
1602                         if (db->db_last_dirty ||
1603                             (db->db_blkptr && !BP_IS_HOLE(db->db_blkptr))) {
1604                                 rw_exit(&dn->dn_struct_rwlock);
1605                                 dbuf_will_dirty(db, tx);
1606                                 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
1607                                 bzero(db->db.db_data, tail);
1608                         }
1609                         dbuf_rele(db, FTAG);
1610                 }
1611                 len -= tail;
1612         }
1613 
1614         /* If the range did not include a full block, we are done */
1615         if (len == 0)
1616                 goto out;
1617 
1618         ASSERT(IS_P2ALIGNED(off, blksz));
1619         ASSERT(trunc || IS_P2ALIGNED(len, blksz));
1620         blkid = off >> blkshift;
1621         nblks = len >> blkshift;
1622         if (trunc)
1623                 nblks += 1;
1624 
1625         /*
1626          * Read in and mark all the level-1 indirects dirty,
1627          * so that they will stay in memory until syncing phase.
1628          * Always dirty the first and last indirect to make sure
1629          * we dirty all the partial indirects.
1630          */
1631         if (dn->dn_nlevels > 1) {
1632                 uint64_t i, first, last;
1633                 int shift = epbs + dn->dn_datablkshift;
1634 
1635                 first = blkid >> epbs;
1636                 if (db = dbuf_hold_level(dn, 1, first, FTAG)) {
1637                         dbuf_will_dirty(db, tx);
1638                         dbuf_rele(db, FTAG);
1639                 }
1640                 if (trunc)
1641                         last = dn->dn_maxblkid >> epbs;
1642                 else
1643                         last = (blkid + nblks - 1) >> epbs;
1644                 if (last > first && (db = dbuf_hold_level(dn, 1, last, FTAG))) {
1645                         dbuf_will_dirty(db, tx);
1646                         dbuf_rele(db, FTAG);
1647                 }
1648                 for (i = first + 1; i < last; i++) {
1649                         uint64_t ibyte = i << shift;
1650                         int err;
1651 
1652                         err = dnode_next_offset(dn,
1653                             DNODE_FIND_HAVELOCK, &ibyte, 1, 1, 0);
1654                         i = ibyte >> shift;
1655                         if (err == ESRCH || i >= last)
1656                                 break;
1657                         ASSERT(err == 0);
1658                         db = dbuf_hold_level(dn, 1, i, FTAG);
1659                         if (db) {
1660                                 dbuf_will_dirty(db, tx);
1661                                 dbuf_rele(db, FTAG);
1662                         }
1663                 }
1664         }
1665 done:
1666         /*
1667          * Add this range to the dnode range list.
1668          * We will finish up this free operation in the syncing phase.
1669          */
1670         mutex_enter(&dn->dn_mtx);
1671         dnode_clear_range(dn, blkid, nblks, tx);
1672         {
1673                 free_range_t *rp, *found;
1674                 avl_index_t where;
1675                 avl_tree_t *tree = &dn->dn_ranges[tx->tx_txg&TXG_MASK];
1676 
1677                 /* Add new range to dn_ranges */
1678                 rp = kmem_alloc(sizeof (free_range_t), KM_SLEEP);
1679                 rp->fr_blkid = blkid;
1680                 rp->fr_nblks = nblks;
1681                 found = avl_find(tree, rp, &where);
1682                 ASSERT(found == NULL);
1683                 avl_insert(tree, rp, where);
1684                 dprintf_dnode(dn, "blkid=%llu nblks=%llu txg=%llu\n",
1685                     blkid, nblks, tx->tx_txg);
1686         }
1687         mutex_exit(&dn->dn_mtx);
1688 
1689         dbuf_free_range(dn, blkid, blkid + nblks - 1, tx);
1690         dnode_setdirty(dn, tx);
1691 out:
1692         if (trunc && dn->dn_maxblkid >= (off >> blkshift))
1693                 dn->dn_maxblkid = (off >> blkshift ? (off >> blkshift) - 1 : 0);
1694 
1695         rw_exit(&dn->dn_struct_rwlock);
1696 }
1697 
1698 static boolean_t
1699 dnode_spill_freed(dnode_t *dn)
1700 {
1701         int i;
1702 
1703         mutex_enter(&dn->dn_mtx);
1704         for (i = 0; i < TXG_SIZE; i++) {
1705                 if (dn->dn_rm_spillblk[i] == DN_KILL_SPILLBLK)
1706                         break;
1707         }
1708         mutex_exit(&dn->dn_mtx);
1709         return (i < TXG_SIZE);
1710 }
1711 
1712 /* return TRUE if this blkid was freed in a recent txg, or FALSE if it wasn't */
1713 uint64_t
1714 dnode_block_freed(dnode_t *dn, uint64_t blkid)
1715 {
1716         free_range_t range_tofind;
1717         void *dp = spa_get_dsl(dn->dn_objset->os_spa);
1718         int i;
1719 
1720         if (blkid == DMU_BONUS_BLKID)
1721                 return (FALSE);
1722 
1723         /*
1724          * If we're in the process of opening the pool, dp will not be
1725          * set yet, but there shouldn't be anything dirty.
1726          */
1727         if (dp == NULL)
1728                 return (FALSE);
1729 
1730         if (dn->dn_free_txg)
1731                 return (TRUE);
1732 
1733         if (blkid == DMU_SPILL_BLKID)
1734                 return (dnode_spill_freed(dn));
1735 
1736         range_tofind.fr_blkid = blkid;
1737         mutex_enter(&dn->dn_mtx);
1738         for (i = 0; i < TXG_SIZE; i++) {
1739                 free_range_t *range_found;
1740                 avl_index_t idx;
1741 
1742                 range_found = avl_find(&dn->dn_ranges[i], &range_tofind, &idx);
1743                 if (range_found) {
1744                         ASSERT(range_found->fr_nblks > 0);
1745                         break;
1746                 }
1747                 range_found = avl_nearest(&dn->dn_ranges[i], idx, AVL_BEFORE);
1748                 if (range_found &&
1749                     range_found->fr_blkid + range_found->fr_nblks > blkid)
1750                         break;
1751         }
1752         mutex_exit(&dn->dn_mtx);
1753         return (i < TXG_SIZE);
1754 }
1755 
1756 /* call from syncing context when we actually write/free space for this dnode */
1757 void
1758 dnode_diduse_space(dnode_t *dn, int64_t delta)
1759 {
1760         uint64_t space;
1761         dprintf_dnode(dn, "dn=%p dnp=%p used=%llu delta=%lld\n",
1762             dn, dn->dn_phys,
1763             (u_longlong_t)dn->dn_phys->dn_used,
1764             (longlong_t)delta);
1765 
1766         mutex_enter(&dn->dn_mtx);
1767         space = DN_USED_BYTES(dn->dn_phys);
1768         if (delta > 0) {
1769                 ASSERT3U(space + delta, >=, space); /* no overflow */
1770         } else {
1771                 ASSERT3U(space, >=, -delta); /* no underflow */
1772         }
1773         space += delta;
1774         if (spa_version(dn->dn_objset->os_spa) < SPA_VERSION_DNODE_BYTES) {
1775                 ASSERT((dn->dn_phys->dn_flags & DNODE_FLAG_USED_BYTES) == 0);
1776                 ASSERT0(P2PHASE(space, 1<<DEV_BSHIFT));
1777                 dn->dn_phys->dn_used = space >> DEV_BSHIFT;
1778         } else {
1779                 dn->dn_phys->dn_used = space;
1780                 dn->dn_phys->dn_flags |= DNODE_FLAG_USED_BYTES;
1781         }
1782         mutex_exit(&dn->dn_mtx);
1783 }
1784 
1785 /*
1786  * Call when we think we're going to write/free space in open context.
1787  * Be conservative (ie. OK to write less than this or free more than
1788  * this, but don't write more or free less).
1789  */
1790 void
1791 dnode_willuse_space(dnode_t *dn, int64_t space, dmu_tx_t *tx)
1792 {
1793         objset_t *os = dn->dn_objset;
1794         dsl_dataset_t *ds = os->os_dsl_dataset;
1795 
1796         if (space > 0)
1797                 space = spa_get_asize(os->os_spa, space);
1798 
1799         if (ds)
1800                 dsl_dir_willuse_space(ds->ds_dir, space, tx);
1801 
1802         dmu_tx_willuse_space(tx, space);
1803 }
1804 
1805 /*
1806  * This function scans a block at the indicated "level" looking for
1807  * a hole or data (depending on 'flags').  If level > 0, then we are
1808  * scanning an indirect block looking at its pointers.  If level == 0,
1809  * then we are looking at a block of dnodes.  If we don't find what we
1810  * are looking for in the block, we return ESRCH.  Otherwise, return
1811  * with *offset pointing to the beginning (if searching forwards) or
1812  * end (if searching backwards) of the range covered by the block
1813  * pointer we matched on (or dnode).
1814  *
1815  * The basic search algorithm used below by dnode_next_offset() is to
1816  * use this function to search up the block tree (widen the search) until
1817  * we find something (i.e., we don't return ESRCH) and then search back
1818  * down the tree (narrow the search) until we reach our original search
1819  * level.
1820  */
1821 static int
1822 dnode_next_offset_level(dnode_t *dn, int flags, uint64_t *offset,
1823         int lvl, uint64_t blkfill, uint64_t txg)
1824 {
1825         dmu_buf_impl_t *db = NULL;
1826         void *data = NULL;
1827         uint64_t epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
1828         uint64_t epb = 1ULL << epbs;
1829         uint64_t minfill, maxfill;
1830         boolean_t hole;
1831         int i, inc, error, span;
1832 
1833         dprintf("probing object %llu offset %llx level %d of %u\n",
1834             dn->dn_object, *offset, lvl, dn->dn_phys->dn_nlevels);
1835 
1836         hole = ((flags & DNODE_FIND_HOLE) != 0);
1837         inc = (flags & DNODE_FIND_BACKWARDS) ? -1 : 1;
1838         ASSERT(txg == 0 || !hole);
1839 
1840         if (lvl == dn->dn_phys->dn_nlevels) {
1841                 error = 0;
1842                 epb = dn->dn_phys->dn_nblkptr;
1843                 data = dn->dn_phys->dn_blkptr;
1844         } else {
1845                 uint64_t blkid = dbuf_whichblock(dn, *offset) >> (epbs * lvl);
1846                 error = dbuf_hold_impl(dn, lvl, blkid, TRUE, FTAG, &db);
1847                 if (error) {
1848                         if (error != ENOENT)
1849                                 return (error);
1850                         if (hole)
1851                                 return (0);
1852                         /*
1853                          * This can only happen when we are searching up
1854                          * the block tree for data.  We don't really need to
1855                          * adjust the offset, as we will just end up looking
1856                          * at the pointer to this block in its parent, and its
1857                          * going to be unallocated, so we will skip over it.
1858                          */
1859                         return (SET_ERROR(ESRCH));
1860                 }
1861                 error = dbuf_read(db, NULL, DB_RF_CANFAIL | DB_RF_HAVESTRUCT);
1862                 if (error) {
1863                         dbuf_rele(db, FTAG);
1864                         return (error);
1865                 }
1866                 data = db->db.db_data;
1867         }
1868 
1869         if (db && txg &&
1870             (db->db_blkptr == NULL || db->db_blkptr->blk_birth <= txg)) {
1871                 /*
1872                  * This can only happen when we are searching up the tree
1873                  * and these conditions mean that we need to keep climbing.
1874                  */
1875                 error = SET_ERROR(ESRCH);
1876         } else if (lvl == 0) {
1877                 dnode_phys_t *dnp = data;
1878                 span = DNODE_SHIFT;
1879                 ASSERT(dn->dn_type == DMU_OT_DNODE);
1880 
1881                 for (i = (*offset >> span) & (blkfill - 1);
1882                     i >= 0 && i < blkfill; i += inc) {
1883                         if ((dnp[i].dn_type == DMU_OT_NONE) == hole)
1884                                 break;
1885                         *offset += (1ULL << span) * inc;
1886                 }
1887                 if (i < 0 || i == blkfill)
1888                         error = SET_ERROR(ESRCH);
1889         } else {
1890                 blkptr_t *bp = data;
1891                 uint64_t start = *offset;
1892                 span = (lvl - 1) * epbs + dn->dn_datablkshift;
1893                 minfill = 0;
1894                 maxfill = blkfill << ((lvl - 1) * epbs);
1895 
1896                 if (hole)
1897                         maxfill--;
1898                 else
1899                         minfill++;
1900 
1901                 *offset = *offset >> span;
1902                 for (i = BF64_GET(*offset, 0, epbs);
1903                     i >= 0 && i < epb; i += inc) {
1904                         if (bp[i].blk_fill >= minfill &&
1905                             bp[i].blk_fill <= maxfill &&
1906                             (hole || bp[i].blk_birth > txg))
1907                                 break;
1908                         if (inc > 0 || *offset > 0)
1909                                 *offset += inc;
1910                 }
1911                 *offset = *offset << span;
1912                 if (inc < 0) {
1913                         /* traversing backwards; position offset at the end */
1914                         ASSERT3U(*offset, <=, start);
1915                         *offset = MIN(*offset + (1ULL << span) - 1, start);
1916                 } else if (*offset < start) {
1917                         *offset = start;
1918                 }
1919                 if (i < 0 || i >= epb)
1920                         error = SET_ERROR(ESRCH);
1921         }
1922 
1923         if (db)
1924                 dbuf_rele(db, FTAG);
1925 
1926         return (error);
1927 }
1928 
1929 /*
1930  * Find the next hole, data, or sparse region at or after *offset.
1931  * The value 'blkfill' tells us how many items we expect to find
1932  * in an L0 data block; this value is 1 for normal objects,
1933  * DNODES_PER_BLOCK for the meta dnode, and some fraction of
1934  * DNODES_PER_BLOCK when searching for sparse regions thereof.
1935  *
1936  * Examples:
1937  *
1938  * dnode_next_offset(dn, flags, offset, 1, 1, 0);
1939  *      Finds the next/previous hole/data in a file.
1940  *      Used in dmu_offset_next().
1941  *
1942  * dnode_next_offset(mdn, flags, offset, 0, DNODES_PER_BLOCK, txg);
1943  *      Finds the next free/allocated dnode an objset's meta-dnode.
1944  *      Only finds objects that have new contents since txg (ie.
1945  *      bonus buffer changes and content removal are ignored).
1946  *      Used in dmu_object_next().
1947  *
1948  * dnode_next_offset(mdn, DNODE_FIND_HOLE, offset, 2, DNODES_PER_BLOCK >> 2, 0);
1949  *      Finds the next L2 meta-dnode bp that's at most 1/4 full.
1950  *      Used in dmu_object_alloc().
1951  */
1952 int
1953 dnode_next_offset(dnode_t *dn, int flags, uint64_t *offset,
1954     int minlvl, uint64_t blkfill, uint64_t txg)
1955 {
1956         uint64_t initial_offset = *offset;
1957         int lvl, maxlvl;
1958         int error = 0;
1959 
1960         if (!(flags & DNODE_FIND_HAVELOCK))
1961                 rw_enter(&dn->dn_struct_rwlock, RW_READER);
1962 
1963         if (dn->dn_phys->dn_nlevels == 0) {
1964                 error = SET_ERROR(ESRCH);
1965                 goto out;
1966         }
1967 
1968         if (dn->dn_datablkshift == 0) {
1969                 if (*offset < dn->dn_datablksz) {
1970                         if (flags & DNODE_FIND_HOLE)
1971                                 *offset = dn->dn_datablksz;
1972                 } else {
1973                         error = SET_ERROR(ESRCH);
1974                 }
1975                 goto out;
1976         }
1977 
1978         maxlvl = dn->dn_phys->dn_nlevels;
1979 
1980         for (lvl = minlvl; lvl <= maxlvl; lvl++) {
1981                 error = dnode_next_offset_level(dn,
1982                     flags, offset, lvl, blkfill, txg);
1983                 if (error != ESRCH)
1984                         break;
1985         }
1986 
1987         while (error == 0 && --lvl >= minlvl) {
1988                 error = dnode_next_offset_level(dn,
1989                     flags, offset, lvl, blkfill, txg);
1990         }
1991 
1992         if (error == 0 && (flags & DNODE_FIND_BACKWARDS ?
1993             initial_offset < *offset : initial_offset > *offset))
1994                 error = SET_ERROR(ESRCH);
1995 out:
1996         if (!(flags & DNODE_FIND_HAVELOCK))
1997                 rw_exit(&dn->dn_struct_rwlock);
1998 
1999         return (error);
2000 }