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