fs/zfs/dnode_sync.c

	dnode_sync.c revision a2cdcdd260232b58202b11a9bfc0103c9449ed52
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
 * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
 */

#include <sys/zfs_context.h>
#include <sys/dbuf.h>
#include <sys/dnode.h>
#include <sys/dmu.h>
#include <sys/dmu_tx.h>
#include <sys/dmu_objset.h>
#include <sys/dsl_dataset.h>
#include <sys/spa.h>
#include <sys/range_tree.h>
#include <sys/zfeature.h>

static void
dnode_increase_indirection(dnode_t *dn, dmu_tx_t *tx)
{
    dmu_buf_impl_t *db;
    int txgoff = tx->tx_txg & TXG_MASK;
    int nblkptr = dn->dn_phys->dn_nblkptr;
    int old_toplvl = dn->dn_phys->dn_nlevels - 1;
    int new_level = dn->dn_next_nlevels[txgoff];
    int i;

    rw_enter(&dn->dn_struct_rwlock, RW_WRITER);

    /* this dnode can't be paged out because it's dirty */
    ASSERT(dn->dn_phys->dn_type != DMU_OT_NONE);
    ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
    ASSERT(new_level > 1 && dn->dn_phys->dn_nlevels > 0);

    db = dbuf_hold_level(dn, dn->dn_phys->dn_nlevels, 0, FTAG);
    ASSERT(db != NULL);

    dn->dn_phys->dn_nlevels = new_level;
    dprintf("os=%p obj=%llu, increase to %d\n", dn->dn_objset,
        dn->dn_object, dn->dn_phys->dn_nlevels);

    /* check for existing blkptrs in the dnode */
    for (i = 0; i < nblkptr; i++)
        if (!BP_IS_HOLE(&dn->dn_phys->dn_blkptr[i]))
            break;
    if (i != nblkptr) {
        /* transfer dnode's block pointers to new indirect block */
        (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED|DB_RF_HAVESTRUCT);
        ASSERT(db->db.db_data);
        ASSERT(arc_released(db->db_buf));
        ASSERT3U(sizeof (blkptr_t) * nblkptr, <=, db->db.db_size);
        bcopy(dn->dn_phys->dn_blkptr, db->db.db_data,
            sizeof (blkptr_t) * nblkptr);
        arc_buf_freeze(db->db_buf);
    }

    /* set dbuf's parent pointers to new indirect buf */
    for (i = 0; i < nblkptr; i++) {
        dmu_buf_impl_t *child =
            dbuf_find(dn->dn_objset, dn->dn_object, old_toplvl, i);

        if (child == NULL)
            continue;
#ifdef  DEBUG
        DB_DNODE_ENTER(child);
        ASSERT3P(DB_DNODE(child), ==, dn);
        DB_DNODE_EXIT(child);
#endif  /* DEBUG */
        if (child->db_parent && child->db_parent != dn->dn_dbuf) {
            ASSERT(child->db_parent->db_level == db->db_level);
            ASSERT(child->db_blkptr !=
                &dn->dn_phys->dn_blkptr[child->db_blkid]);
            mutex_exit(&child->db_mtx);
            continue;
        }
        ASSERT(child->db_parent == NULL ||
            child->db_parent == dn->dn_dbuf);

        child->db_parent = db;
        dbuf_add_ref(db, child);
        if (db->db.db_data)
            child->db_blkptr = (blkptr_t *)db->db.db_data + i;
        else
            child->db_blkptr = NULL;
        dprintf_dbuf_bp(child, child->db_blkptr,
            "changed db_blkptr to new indirect %s", "");

        mutex_exit(&child->db_mtx);
    }

    bzero(dn->dn_phys->dn_blkptr, sizeof (blkptr_t) * nblkptr);

    dbuf_rele(db, FTAG);

    rw_exit(&dn->dn_struct_rwlock);
}

static void
free_blocks(dnode_t *dn, blkptr_t *bp, int num, dmu_tx_t *tx)
{
    dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset;
    uint64_t bytesfreed = 0;

    dprintf("ds=%p obj=%llx num=%d\n", ds, dn->dn_object, num);

    for (int i = 0; i < num; i++, bp++) {
        if (BP_IS_HOLE(bp))
            continue;

        bytesfreed += dsl_dataset_block_kill(ds, bp, tx, B_FALSE);
        ASSERT3U(bytesfreed, <=, DN_USED_BYTES(dn->dn_phys));

        /*
         * Save some useful information on the holes being
         * punched, including logical size, type, and indirection
         * level. Retaining birth time enables detection of when
         * holes are punched for reducing the number of free
         * records transmitted during a zfs send.
         */

        uint64_t lsize = BP_GET_LSIZE(bp);
        dmu_object_type_t type = BP_GET_TYPE(bp);
        uint64_t lvl = BP_GET_LEVEL(bp);

        bzero(bp, sizeof (blkptr_t));

        if (spa_feature_is_active(dn->dn_objset->os_spa,
            SPA_FEATURE_HOLE_BIRTH)) {
            BP_SET_LSIZE(bp, lsize);
            BP_SET_TYPE(bp, type);
            BP_SET_LEVEL(bp, lvl);
            BP_SET_BIRTH(bp, dmu_tx_get_txg(tx), 0);
        }
    }
    dnode_diduse_space(dn, -bytesfreed);
}

#ifdef ZFS_DEBUG
static void
free_verify(dmu_buf_impl_t *db, uint64_t start, uint64_t end, dmu_tx_t *tx)
{
    int off, num;
    int i, err, epbs;
    uint64_t txg = tx->tx_txg;
    dnode_t *dn;

    DB_DNODE_ENTER(db);
    dn = DB_DNODE(db);
    epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
    off = start - (db->db_blkid * 1<<epbs);
    num = end - start + 1;

    ASSERT3U(off, >=, 0);
    ASSERT3U(num, >=, 0);
    ASSERT3U(db->db_level, >, 0);
    ASSERT3U(db->db.db_size, ==, 1 << dn->dn_phys->dn_indblkshift);
    ASSERT3U(off+num, <=, db->db.db_size >> SPA_BLKPTRSHIFT);
    ASSERT(db->db_blkptr != NULL);

    for (i = off; i < off+num; i++) {
        uint64_t *buf;
        dmu_buf_impl_t *child;
        dbuf_dirty_record_t *dr;
        int j;

        ASSERT(db->db_level == 1);

        rw_enter(&dn->dn_struct_rwlock, RW_READER);
        err = dbuf_hold_impl(dn, db->db_level-1,
            (db->db_blkid << epbs) + i, TRUE, FALSE, FTAG, &child);
        rw_exit(&dn->dn_struct_rwlock);
        if (err == ENOENT)
            continue;
        ASSERT(err == 0);
        ASSERT(child->db_level == 0);
        dr = child->db_last_dirty;
        while (dr && dr->dr_txg > txg)
            dr = dr->dr_next;
        ASSERT(dr == NULL || dr->dr_txg == txg);

        /* data_old better be zeroed */
        if (dr) {
            buf = dr->dt.dl.dr_data->b_data;
            for (j = 0; j < child->db.db_size >> 3; j++) {
                if (buf[j] != 0) {
                    panic("freed data not zero: "
                        "child=%p i=%d off=%d num=%d\n",
                        (void *)child, i, off, num);
                }
            }
        }

        /*
         * db_data better be zeroed unless it's dirty in a
         * future txg.
         */
        mutex_enter(&child->db_mtx);
        buf = child->db.db_data;
        if (buf != NULL && child->db_state != DB_FILL &&
            child->db_last_dirty == NULL) {
            for (j = 0; j < child->db.db_size >> 3; j++) {
                if (buf[j] != 0) {
                    panic("freed data not zero: "
                        "child=%p i=%d off=%d num=%d\n",
                        (void *)child, i, off, num);
                }
            }
        }
        mutex_exit(&child->db_mtx);

        dbuf_rele(child, FTAG);
    }
    DB_DNODE_EXIT(db);
}
#endif

static void
free_children(dmu_buf_impl_t *db, uint64_t blkid, uint64_t nblks,
    dmu_tx_t *tx)
{
    dnode_t *dn;
    blkptr_t *bp;
    dmu_buf_impl_t *subdb;
    uint64_t start, end, dbstart, dbend, i;
    int epbs, shift;

    /*
     * There is a small possibility that this block will not be cached:
     *   1 - if level > 1 and there are no children with level <= 1
     *   2 - if this block was evicted since we read it from
     *   dmu_tx_hold_free().
     */
    if (db->db_state != DB_CACHED)
        (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED);

    dbuf_release_bp(db);
    bp = db->db.db_data;

    DB_DNODE_ENTER(db);
    dn = DB_DNODE(db);
    epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
    shift = (db->db_level - 1) * epbs;
    dbstart = db->db_blkid << epbs;
    start = blkid >> shift;
    if (dbstart < start) {
        bp += start - dbstart;
    } else {
        start = dbstart;
    }
    dbend = ((db->db_blkid + 1) << epbs) - 1;
    end = (blkid + nblks - 1) >> shift;
    if (dbend <= end)
        end = dbend;

    ASSERT3U(start, <=, end);

    if (db->db_level == 1) {
        FREE_VERIFY(db, start, end, tx);
        free_blocks(dn, bp, end-start+1, tx);
    } else {
        for (i = start; i <= end; i++, bp++) {
            if (BP_IS_HOLE(bp))
                continue;
            rw_enter(&dn->dn_struct_rwlock, RW_READER);
            VERIFY0(dbuf_hold_impl(dn, db->db_level - 1,
                i, TRUE, FALSE, FTAG, &subdb));
            rw_exit(&dn->dn_struct_rwlock);
            ASSERT3P(bp, ==, subdb->db_blkptr);

            free_children(subdb, blkid, nblks, tx);
            dbuf_rele(subdb, FTAG);
        }
    }

    /* If this whole block is free, free ourself too. */
    for (i = 0, bp = db->db.db_data; i < 1 << epbs; i++, bp++) {
        if (!BP_IS_HOLE(bp))
            break;
    }
    if (i == 1 << epbs) {
        /* didn't find any non-holes */
        bzero(db->db.db_data, db->db.db_size);
        free_blocks(dn, db->db_blkptr, 1, tx);
    } else {
        /*
         * Partial block free; must be marked dirty so that it
         * will be written out.
         */
        ASSERT(db->db_dirtycnt > 0);
    }

    DB_DNODE_EXIT(db);
    arc_buf_freeze(db->db_buf);
}

/*
 * Traverse the indicated range of the provided file
 * and "free" all the blocks contained there.
 */
static void
dnode_sync_free_range_impl(dnode_t *dn, uint64_t blkid, uint64_t nblks,
    dmu_tx_t *tx)
{
    blkptr_t *bp = dn->dn_phys->dn_blkptr;
    int dnlevel = dn->dn_phys->dn_nlevels;
    boolean_t trunc = B_FALSE;

    if (blkid > dn->dn_phys->dn_maxblkid)
        return;

    ASSERT(dn->dn_phys->dn_maxblkid < UINT64_MAX);
    if (blkid + nblks > dn->dn_phys->dn_maxblkid) {
        nblks = dn->dn_phys->dn_maxblkid - blkid + 1;
        trunc = B_TRUE;
    }

    /* There are no indirect blocks in the object */
    if (dnlevel == 1) {
        if (blkid >= dn->dn_phys->dn_nblkptr) {
            /* this range was never made persistent */
            return;
        }
        ASSERT3U(blkid + nblks, <=, dn->dn_phys->dn_nblkptr);
        free_blocks(dn, bp + blkid, nblks, tx);
    } else {
        int shift = (dnlevel - 1) *
            (dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT);
        int start = blkid >> shift;
        int end = (blkid + nblks - 1) >> shift;
        dmu_buf_impl_t *db;

        ASSERT(start < dn->dn_phys->dn_nblkptr);
        bp += start;
        for (int i = start; i <= end; i++, bp++) {
            if (BP_IS_HOLE(bp))
                continue;
            rw_enter(&dn->dn_struct_rwlock, RW_READER);
            VERIFY0(dbuf_hold_impl(dn, dnlevel - 1, i,
                TRUE, FALSE, FTAG, &db));
            rw_exit(&dn->dn_struct_rwlock);

            free_children(db, blkid, nblks, tx);
            dbuf_rele(db, FTAG);
        }
    }

    if (trunc) {
        dn->dn_phys->dn_maxblkid = blkid == 0 ? 0 : blkid - 1;

        uint64_t off = (dn->dn_phys->dn_maxblkid + 1) *
            (dn->dn_phys->dn_datablkszsec << SPA_MINBLOCKSHIFT);
        ASSERT(off < dn->dn_phys->dn_maxblkid ||
            dn->dn_phys->dn_maxblkid == 0 ||
            dnode_next_offset(dn, 0, &off, 1, 1, 0) != 0);
    }
}

typedef struct dnode_sync_free_range_arg {
    dnode_t *dsfra_dnode;
    dmu_tx_t *dsfra_tx;
} dnode_sync_free_range_arg_t;

static void
dnode_sync_free_range(void *arg, uint64_t blkid, uint64_t nblks)
{
    dnode_sync_free_range_arg_t *dsfra = arg;
    dnode_t *dn = dsfra->dsfra_dnode;

    mutex_exit(&dn->dn_mtx);
    dnode_sync_free_range_impl(dn, blkid, nblks, dsfra->dsfra_tx);
    mutex_enter(&dn->dn_mtx);
}

/*
 * Try to kick all the dnode's dbufs out of the cache...
 */
void
dnode_evict_dbufs(dnode_t *dn)
{
    dmu_buf_impl_t db_marker;
    dmu_buf_impl_t *db, *db_next;

    mutex_enter(&dn->dn_dbufs_mtx);
    for (db = avl_first(&dn->dn_dbufs); db != NULL; db = db_next) {

#ifdef  DEBUG
        DB_DNODE_ENTER(db);
        ASSERT3P(DB_DNODE(db), ==, dn);
        DB_DNODE_EXIT(db);
#endif  /* DEBUG */

        mutex_enter(&db->db_mtx);
        if (db->db_state != DB_EVICTING &&
            refcount_is_zero(&db->db_holds)) {
            db_marker.db_level = db->db_level;
            db_marker.db_blkid = db->db_blkid;
            db_marker.db_state = DB_SEARCH;
            avl_insert_here(&dn->dn_dbufs, &db_marker, db,
                AVL_BEFORE);

            dbuf_clear(db);

            db_next = AVL_NEXT(&dn->dn_dbufs, &db_marker);
            avl_remove(&dn->dn_dbufs, &db_marker);
        } else {
            mutex_exit(&db->db_mtx);
            db_next = AVL_NEXT(&dn->dn_dbufs, db);
        }
    }
    mutex_exit(&dn->dn_dbufs_mtx);

    dnode_evict_bonus(dn);
}

void
dnode_evict_bonus(dnode_t *dn)
{
    rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
    if (dn->dn_bonus && refcount_is_zero(&dn->dn_bonus->db_holds)) {
        mutex_enter(&dn->dn_bonus->db_mtx);
        dbuf_evict(dn->dn_bonus);
        dn->dn_bonus = NULL;
    }
    rw_exit(&dn->dn_struct_rwlock);
}

static void
dnode_undirty_dbufs(list_t *list)
{
    dbuf_dirty_record_t *dr;

    while (dr = list_head(list)) {
        dmu_buf_impl_t *db = dr->dr_dbuf;
        uint64_t txg = dr->dr_txg;

        if (db->db_level != 0)
            dnode_undirty_dbufs(&dr->dt.di.dr_children);

        mutex_enter(&db->db_mtx);
        /* XXX - use dbuf_undirty()? */
        list_remove(list, dr);
        ASSERT(db->db_last_dirty == dr);
        db->db_last_dirty = NULL;
        db->db_dirtycnt -= 1;
        if (db->db_level == 0) {
            ASSERT(db->db_blkid == DMU_BONUS_BLKID ||
                dr->dt.dl.dr_data == db->db_buf);
            dbuf_unoverride(dr);
        } else {
            mutex_destroy(&dr->dt.di.dr_mtx);
            list_destroy(&dr->dt.di.dr_children);
        }
        kmem_free(dr, sizeof (dbuf_dirty_record_t));
        dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg);
    }
}

static void
dnode_sync_free(dnode_t *dn, dmu_tx_t *tx)
{
    int txgoff = tx->tx_txg & TXG_MASK;

    ASSERT(dmu_tx_is_syncing(tx));

    /*
     * Our contents should have been freed in dnode_sync() by the
     * free range record inserted by the caller of dnode_free().
     */
    ASSERT0(DN_USED_BYTES(dn->dn_phys));
    ASSERT(BP_IS_HOLE(dn->dn_phys->dn_blkptr));

    dnode_undirty_dbufs(&dn->dn_dirty_records[txgoff]);
    dnode_evict_dbufs(dn);
    ASSERT(avl_is_empty(&dn->dn_dbufs));

    /*
     * XXX - It would be nice to assert this, but we may still
     * have residual holds from async evictions from the arc...
     *
     * zfs_obj_to_path() also depends on this being
     * commented out.
     *
     * ASSERT3U(refcount_count(&dn->dn_holds), ==, 1);
     */

    /* Undirty next bits */
    dn->dn_next_nlevels[txgoff] = 0;
    dn->dn_next_indblkshift[txgoff] = 0;
    dn->dn_next_blksz[txgoff] = 0;

    /* ASSERT(blkptrs are zero); */
    ASSERT(dn->dn_phys->dn_type != DMU_OT_NONE);
    ASSERT(dn->dn_type != DMU_OT_NONE);

    ASSERT(dn->dn_free_txg > 0);
    if (dn->dn_allocated_txg != dn->dn_free_txg)
        dmu_buf_will_dirty(&dn->dn_dbuf->db, tx);
    bzero(dn->dn_phys, sizeof (dnode_phys_t));

    mutex_enter(&dn->dn_mtx);
    dn->dn_type = DMU_OT_NONE;
    dn->dn_maxblkid = 0;
    dn->dn_allocated_txg = 0;
    dn->dn_free_txg = 0;
    dn->dn_have_spill = B_FALSE;
    mutex_exit(&dn->dn_mtx);

    ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);

    dnode_rele(dn, (void *)(uintptr_t)tx->tx_txg);
    /*
     * Now that we've released our hold, the dnode may
     * be evicted, so we musn't access it.
     */
}

/*
 * Write out the dnode's dirty buffers.
 */
void
dnode_sync(dnode_t *dn, dmu_tx_t *tx)
{
    dnode_phys_t *dnp = dn->dn_phys;
    int txgoff = tx->tx_txg & TXG_MASK;
    list_t *list = &dn->dn_dirty_records[txgoff];
    static const dnode_phys_t zerodn = { 0 };
    boolean_t kill_spill = B_FALSE;

    ASSERT(dmu_tx_is_syncing(tx));
    ASSERT(dnp->dn_type != DMU_OT_NONE || dn->dn_allocated_txg);
    ASSERT(dnp->dn_type != DMU_OT_NONE ||
        bcmp(dnp, &zerodn, DNODE_SIZE) == 0);
    DNODE_VERIFY(dn);

    ASSERT(dn->dn_dbuf == NULL || arc_released(dn->dn_dbuf->db_buf));

    if (dmu_objset_userused_enabled(dn->dn_objset) &&
        !DMU_OBJECT_IS_SPECIAL(dn->dn_object)) {
        mutex_enter(&dn->dn_mtx);
        dn->dn_oldused = DN_USED_BYTES(dn->dn_phys);
        dn->dn_oldflags = dn->dn_phys->dn_flags;
        dn->dn_phys->dn_flags |= DNODE_FLAG_USERUSED_ACCOUNTED;
        mutex_exit(&dn->dn_mtx);
        dmu_objset_userquota_get_ids(dn, B_FALSE, tx);
    } else {
        /* Once we account for it, we should always account for it. */
        ASSERT(!(dn->dn_phys->dn_flags &
            DNODE_FLAG_USERUSED_ACCOUNTED));
    }

    mutex_enter(&dn->dn_mtx);
    if (dn->dn_allocated_txg == tx->tx_txg) {
        /* The dnode is newly allocated or reallocated */
        if (dnp->dn_type == DMU_OT_NONE) {
            /* this is a first alloc, not a realloc */
            dnp->dn_nlevels = 1;
            dnp->dn_nblkptr = dn->dn_nblkptr;
        }

        dnp->dn_type = dn->dn_type;
        dnp->dn_bonustype = dn->dn_bonustype;
        dnp->dn_bonuslen = dn->dn_bonuslen;
    }
    ASSERT(dnp->dn_nlevels > 1 ||
        BP_IS_HOLE(&dnp->dn_blkptr[0]) ||
        BP_IS_EMBEDDED(&dnp->dn_blkptr[0]) ||
        BP_GET_LSIZE(&dnp->dn_blkptr[0]) ==
        dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT);
    ASSERT(dnp->dn_nlevels < 2 ||
        BP_IS_HOLE(&dnp->dn_blkptr[0]) ||
        BP_GET_LSIZE(&dnp->dn_blkptr[0]) == 1 << dnp->dn_indblkshift);

    if (dn->dn_next_type[txgoff] != 0) {
        dnp->dn_type = dn->dn_type;
        dn->dn_next_type[txgoff] = 0;
    }

    if (dn->dn_next_blksz[txgoff] != 0) {
        ASSERT(P2PHASE(dn->dn_next_blksz[txgoff],
            SPA_MINBLOCKSIZE) == 0);
        ASSERT(BP_IS_HOLE(&dnp->dn_blkptr[0]) ||
            dn->dn_maxblkid == 0 || list_head(list) != NULL ||
            dn->dn_next_blksz[txgoff] >> SPA_MINBLOCKSHIFT ==
            dnp->dn_datablkszsec ||
            range_tree_space(dn->dn_free_ranges[txgoff]) != 0);
        dnp->dn_datablkszsec =
            dn->dn_next_blksz[txgoff] >> SPA_MINBLOCKSHIFT;
        dn->dn_next_blksz[txgoff] = 0;
    }

    if (dn->dn_next_bonuslen[txgoff] != 0) {
        if (dn->dn_next_bonuslen[txgoff] == DN_ZERO_BONUSLEN)
            dnp->dn_bonuslen = 0;
        else
            dnp->dn_bonuslen = dn->dn_next_bonuslen[txgoff];
        ASSERT(dnp->dn_bonuslen <= DN_MAX_BONUSLEN);
        dn->dn_next_bonuslen[txgoff] = 0;
    }

    if (dn->dn_next_bonustype[txgoff] != 0) {
        ASSERT(DMU_OT_IS_VALID(dn->dn_next_bonustype[txgoff]));
        dnp->dn_bonustype = dn->dn_next_bonustype[txgoff];
        dn->dn_next_bonustype[txgoff] = 0;
    }

    boolean_t freeing_dnode = dn->dn_free_txg > 0 &&
        dn->dn_free_txg <= tx->tx_txg;

    /*
     * Remove the spill block if we have been explicitly asked to
     * remove it, or if the object is being removed.
     */
    if (dn->dn_rm_spillblk[txgoff] || freeing_dnode) {
        if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR)
            kill_spill = B_TRUE;
        dn->dn_rm_spillblk[txgoff] = 0;
    }

    if (dn->dn_next_indblkshift[txgoff] != 0) {
        ASSERT(dnp->dn_nlevels == 1);
        dnp->dn_indblkshift = dn->dn_next_indblkshift[txgoff];
        dn->dn_next_indblkshift[txgoff] = 0;
    }

    /*
     * Just take the live (open-context) values for checksum and compress.
     * Strictly speaking it's a future leak, but nothing bad happens if we
     * start using the new checksum or compress algorithm a little early.
     */
    dnp->dn_checksum = dn->dn_checksum;
    dnp->dn_compress = dn->dn_compress;

    mutex_exit(&dn->dn_mtx);

    if (kill_spill) {
        free_blocks(dn, &dn->dn_phys->dn_spill, 1, tx);
        mutex_enter(&dn->dn_mtx);
        dnp->dn_flags &= ~DNODE_FLAG_SPILL_BLKPTR;
        mutex_exit(&dn->dn_mtx);
    }

    /* process all the "freed" ranges in the file */
    if (dn->dn_free_ranges[txgoff] != NULL) {
        dnode_sync_free_range_arg_t dsfra;
        dsfra.dsfra_dnode = dn;
        dsfra.dsfra_tx = tx;
        mutex_enter(&dn->dn_mtx);
        range_tree_vacate(dn->dn_free_ranges[txgoff],
            dnode_sync_free_range, &dsfra);
        range_tree_destroy(dn->dn_free_ranges[txgoff]);
        dn->dn_free_ranges[txgoff] = NULL;
        mutex_exit(&dn->dn_mtx);
    }

    if (freeing_dnode) {
        dnode_sync_free(dn, tx);
        return;
    }

    if (dn->dn_next_nlevels[txgoff]) {
        dnode_increase_indirection(dn, tx);
        dn->dn_next_nlevels[txgoff] = 0;
    }

    if (dn->dn_next_nblkptr[txgoff]) {
        /* this should only happen on a realloc */
        ASSERT(dn->dn_allocated_txg == tx->tx_txg);
        if (dn->dn_next_nblkptr[txgoff] > dnp->dn_nblkptr) {
            /* zero the new blkptrs we are gaining */
            bzero(dnp->dn_blkptr + dnp->dn_nblkptr,
                sizeof (blkptr_t) *
                (dn->dn_next_nblkptr[txgoff] - dnp->dn_nblkptr));
#ifdef ZFS_DEBUG
        } else {
            int i;
            ASSERT(dn->dn_next_nblkptr[txgoff] < dnp->dn_nblkptr);
            /* the blkptrs we are losing better be unallocated */
            for (i = dn->dn_next_nblkptr[txgoff];
                i < dnp->dn_nblkptr; i++)
                ASSERT(BP_IS_HOLE(&dnp->dn_blkptr[i]));
#endif
        }
        mutex_enter(&dn->dn_mtx);
        dnp->dn_nblkptr = dn->dn_next_nblkptr[txgoff];
        dn->dn_next_nblkptr[txgoff] = 0;
        mutex_exit(&dn->dn_mtx);
    }

    dbuf_sync_list(list, dn->dn_phys->dn_nlevels - 1, tx);

    if (!DMU_OBJECT_IS_SPECIAL(dn->dn_object)) {
        ASSERT3P(list_head(list), ==, NULL);
        dnode_rele(dn, (void *)(uintptr_t)tx->tx_txg);
    }

    /*
     * Although we have dropped our reference to the dnode, it
     * can't be evicted until its written, and we haven't yet
     * initiated the IO for the dnode's dbuf.
     */
}