fs/zfs/dnode.c

	dnode.c revision f65e61c04bc28ffd6bda04619c84330b420450b5
/*
 * 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 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <sys/zfs_context.h>
#include <sys/dbuf.h>
#include <sys/dnode.h>
#include <sys/dmu.h>
#include <sys/dmu_impl.h>
#include <sys/dmu_tx.h>
#include <sys/dmu_objset.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_dataset.h>
#include <sys/spa.h>
#include <sys/zio.h>
#include <sys/dmu_zfetch.h>

static int free_range_compar(const void *node1, const void *node2);

static kmem_cache_t *dnode_cache;

static dnode_phys_t dnode_phys_zero;

int zfs_default_bs = SPA_MINBLOCKSHIFT;
int zfs_default_ibs = DN_MAX_INDBLKSHIFT;

/* ARGSUSED */
static int
dnode_cons(void *arg, void *unused, int kmflag)
{
    int i;
    dnode_t *dn = arg;
    bzero(dn, sizeof (dnode_t));

    rw_init(&dn->dn_struct_rwlock, NULL, RW_DEFAULT, NULL);
    mutex_init(&dn->dn_mtx, NULL, MUTEX_DEFAULT, NULL);
    mutex_init(&dn->dn_dbufs_mtx, NULL, MUTEX_DEFAULT, NULL);
    refcount_create(&dn->dn_holds);
    refcount_create(&dn->dn_tx_holds);

    for (i = 0; i < TXG_SIZE; i++) {
        avl_create(&dn->dn_ranges[i], free_range_compar,
            sizeof (free_range_t),
            offsetof(struct free_range, fr_node));
        list_create(&dn->dn_dirty_dbufs[i],
            sizeof (dmu_buf_impl_t),
            offsetof(dmu_buf_impl_t, db_dirty_node[i]));
    }

    list_create(&dn->dn_dbufs, sizeof (dmu_buf_impl_t),
        offsetof(dmu_buf_impl_t, db_link));

    return (0);
}

/* ARGSUSED */
static void
dnode_dest(void *arg, void *unused)
{
    int i;
    dnode_t *dn = arg;

    rw_destroy(&dn->dn_struct_rwlock);
    mutex_destroy(&dn->dn_mtx);
    mutex_destroy(&dn->dn_dbufs_mtx);
    refcount_destroy(&dn->dn_holds);
    refcount_destroy(&dn->dn_tx_holds);

    for (i = 0; i < TXG_SIZE; i++) {
        avl_destroy(&dn->dn_ranges[i]);
        list_destroy(&dn->dn_dirty_dbufs[i]);
    }

    list_destroy(&dn->dn_dbufs);
}

void
dnode_init(void)
{
    dnode_cache = kmem_cache_create("dnode_t",
        sizeof (dnode_t),
        0, dnode_cons, dnode_dest, NULL, NULL, NULL, 0);
}

void
dnode_fini(void)
{
    kmem_cache_destroy(dnode_cache);
}


#ifdef ZFS_DEBUG
void
dnode_verify(dnode_t *dn)
{
    int drop_struct_lock = FALSE;

    ASSERT(dn->dn_phys);
    ASSERT(dn->dn_objset);

    ASSERT(dn->dn_phys->dn_type < DMU_OT_NUMTYPES);

    if (!(zfs_flags & ZFS_DEBUG_DNODE_VERIFY))
        return;

    if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
        rw_enter(&dn->dn_struct_rwlock, RW_READER);
        drop_struct_lock = TRUE;
    }
    if (dn->dn_phys->dn_type != DMU_OT_NONE || dn->dn_allocated_txg != 0) {
        int i;
        ASSERT3U(dn->dn_indblkshift, >=, 0);
        ASSERT3U(dn->dn_indblkshift, <=, SPA_MAXBLOCKSHIFT);
        if (dn->dn_datablkshift) {
            ASSERT3U(dn->dn_datablkshift, >=, SPA_MINBLOCKSHIFT);
            ASSERT3U(dn->dn_datablkshift, <=, SPA_MAXBLOCKSHIFT);
            ASSERT3U(1<<dn->dn_datablkshift, ==, dn->dn_datablksz);
        }
        ASSERT3U(dn->dn_nlevels, <=, 30);
        ASSERT3U(dn->dn_type, <=, DMU_OT_NUMTYPES);
        ASSERT3U(dn->dn_nblkptr, >=, 1);
        ASSERT3U(dn->dn_nblkptr, <=, DN_MAX_NBLKPTR);
        ASSERT3U(dn->dn_bonuslen, <=, DN_MAX_BONUSLEN);
        ASSERT3U(dn->dn_datablksz, ==,
            dn->dn_datablkszsec << SPA_MINBLOCKSHIFT);
        ASSERT3U(ISP2(dn->dn_datablksz), ==, dn->dn_datablkshift != 0);
        ASSERT3U((dn->dn_nblkptr - 1) * sizeof (blkptr_t) +
            dn->dn_bonuslen, <=, DN_MAX_BONUSLEN);
        for (i = 0; i < TXG_SIZE; i++) {
            ASSERT3U(dn->dn_next_nlevels[i], <=, dn->dn_nlevels);
        }
    }
    if (dn->dn_phys->dn_type != DMU_OT_NONE)
        ASSERT3U(dn->dn_phys->dn_nlevels, <=, dn->dn_nlevels);
    ASSERT(IS_DNODE_DNODE(dn->dn_object) || dn->dn_dbuf);
    if (dn->dn_dbuf != NULL) {
        ASSERT3P(dn->dn_phys, ==,
            (dnode_phys_t *)dn->dn_dbuf->db.db_data +
            (dn->dn_object % (dn->dn_dbuf->db.db_size >> DNODE_SHIFT)));
    }
    if (drop_struct_lock)
        rw_exit(&dn->dn_struct_rwlock);
}
#endif

void
dnode_byteswap(dnode_phys_t *dnp)
{
    uint64_t *buf64 = (void*)&dnp->dn_blkptr;
    int i;

    if (dnp->dn_type == DMU_OT_NONE) {
        bzero(dnp, sizeof (dnode_phys_t));
        return;
    }

    dnp->dn_type = BSWAP_8(dnp->dn_type);
    dnp->dn_indblkshift = BSWAP_8(dnp->dn_indblkshift);
    dnp->dn_nlevels = BSWAP_8(dnp->dn_nlevels);
    dnp->dn_nblkptr = BSWAP_8(dnp->dn_nblkptr);
    dnp->dn_bonustype = BSWAP_8(dnp->dn_bonustype);
    dnp->dn_checksum = BSWAP_8(dnp->dn_checksum);
    dnp->dn_compress = BSWAP_8(dnp->dn_compress);
    dnp->dn_datablkszsec = BSWAP_16(dnp->dn_datablkszsec);
    dnp->dn_bonuslen = BSWAP_16(dnp->dn_bonuslen);
    dnp->dn_maxblkid = BSWAP_64(dnp->dn_maxblkid);
    dnp->dn_secphys = BSWAP_64(dnp->dn_secphys);

    /*
     * dn_nblkptr is only one byte, so it's OK to read it in either
     * byte order.  We can't read dn_bouslen.
     */
    ASSERT(dnp->dn_indblkshift <= SPA_MAXBLOCKSHIFT);
    ASSERT(dnp->dn_nblkptr <= DN_MAX_NBLKPTR);
    for (i = 0; i < dnp->dn_nblkptr * sizeof (blkptr_t)/8; i++)
        buf64[i] = BSWAP_64(buf64[i]);

    /*
     * OK to check dn_bonuslen for zero, because it won't matter if
     * we have the wrong byte order.  This is necessary because the
     * dnode dnode is smaller than a regular dnode.
     */
    if (dnp->dn_bonuslen != 0) {
        /*
         * Note that the bonus length calculated here may be
         * longer than the actual bonus buffer.  This is because
         * we always put the bonus buffer after the last block
         * pointer (instead of packing it against the end of the
         * dnode buffer).
         */
        int off = (dnp->dn_nblkptr-1) * sizeof (blkptr_t);
        size_t len = DN_MAX_BONUSLEN - off;
        dmu_ot[dnp->dn_bonustype].ot_byteswap(dnp->dn_bonus + off, len);
    }
}

void
dnode_buf_byteswap(void *vbuf, size_t size)
{
    dnode_phys_t *buf = vbuf;
    int i;

    ASSERT3U(sizeof (dnode_phys_t), ==, (1<<DNODE_SHIFT));
    ASSERT((size & (sizeof (dnode_phys_t)-1)) == 0);

    size >>= DNODE_SHIFT;
    for (i = 0; i < size; i++) {
        dnode_byteswap(buf);
        buf++;
    }
}

static int
free_range_compar(const void *node1, const void *node2)
{
    const free_range_t *rp1 = node1;
    const free_range_t *rp2 = node2;

    if (rp1->fr_blkid < rp2->fr_blkid)
        return (-1);
    else if (rp1->fr_blkid > rp2->fr_blkid)
        return (1);
    else return (0);
}

static void
dnode_setdblksz(dnode_t *dn, int size)
{
    ASSERT3U(P2PHASE(size, SPA_MINBLOCKSIZE), ==, 0);
    ASSERT3U(size, <=, SPA_MAXBLOCKSIZE);
    ASSERT3U(size, >=, SPA_MINBLOCKSIZE);
    ASSERT3U(size >> SPA_MINBLOCKSHIFT, <,
        1<<(sizeof (dn->dn_phys->dn_datablkszsec) * 8));
    dn->dn_datablksz = size;
    dn->dn_datablkszsec = size >> SPA_MINBLOCKSHIFT;
    dn->dn_datablkshift = ISP2(size) ? highbit(size - 1) : 0;
}

static dnode_t *
dnode_create(objset_impl_t *os, dnode_phys_t *dnp, dmu_buf_impl_t *db,
    uint64_t object)
{
    dnode_t *dn = kmem_cache_alloc(dnode_cache, KM_SLEEP);
    (void) dnode_cons(dn, NULL, 0); /* XXX */

    dn->dn_objset = os;
    dn->dn_object = object;
    dn->dn_dbuf = db;
    dn->dn_phys = dnp;

    if (dnp->dn_datablkszsec)
        dnode_setdblksz(dn, dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT);
    dn->dn_indblkshift = dnp->dn_indblkshift;
    dn->dn_nlevels = dnp->dn_nlevels;
    dn->dn_type = dnp->dn_type;
    dn->dn_nblkptr = dnp->dn_nblkptr;
    dn->dn_checksum = dnp->dn_checksum;
    dn->dn_compress = dnp->dn_compress;
    dn->dn_bonustype = dnp->dn_bonustype;
    dn->dn_bonuslen = dnp->dn_bonuslen;
    dn->dn_maxblkid = dnp->dn_maxblkid;

    dmu_zfetch_init(&dn->dn_zfetch, dn);

    ASSERT(dn->dn_phys->dn_type < DMU_OT_NUMTYPES);
    mutex_enter(&os->os_lock);
    list_insert_head(&os->os_dnodes, dn);
    mutex_exit(&os->os_lock);

    return (dn);
}

static void
dnode_destroy(dnode_t *dn)
{
    objset_impl_t *os = dn->dn_objset;

    mutex_enter(&os->os_lock);
    list_remove(&os->os_dnodes, dn);
    mutex_exit(&os->os_lock);

    if (dn->dn_dirtyctx_firstset) {
        kmem_free(dn->dn_dirtyctx_firstset, 1);
        dn->dn_dirtyctx_firstset = NULL;
    }
    dmu_zfetch_rele(&dn->dn_zfetch);
    kmem_cache_free(dnode_cache, dn);
}

void
dnode_allocate(dnode_t *dn, dmu_object_type_t ot, int blocksize, int ibs,
    dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
{
    int i;

    if (blocksize == 0)
        blocksize = 1 << zfs_default_bs;
    else if (blocksize > SPA_MAXBLOCKSIZE)
        blocksize = SPA_MAXBLOCKSIZE;
    else
        blocksize = P2ROUNDUP(blocksize, SPA_MINBLOCKSIZE);

    if (ibs == 0)
        ibs = zfs_default_ibs;

    ibs = MIN(MAX(ibs, DN_MIN_INDBLKSHIFT), DN_MAX_INDBLKSHIFT);

    dprintf("os=%p obj=%llu txg=%llu blocksize=%d ibs=%d\n", dn->dn_objset,
        dn->dn_object, tx->tx_txg, blocksize, ibs);

    ASSERT(dn->dn_type == DMU_OT_NONE);
    ASSERT(bcmp(dn->dn_phys, &dnode_phys_zero, sizeof (dnode_phys_t)) == 0);
    ASSERT(dn->dn_phys->dn_type == DMU_OT_NONE);
    ASSERT(ot != DMU_OT_NONE);
    ASSERT3U(ot, <, DMU_OT_NUMTYPES);
    ASSERT((bonustype == DMU_OT_NONE && bonuslen == 0) ||
        (bonustype != DMU_OT_NONE && bonuslen != 0));
    ASSERT3U(bonustype, <, DMU_OT_NUMTYPES);
    ASSERT3U(bonuslen, <=, DN_MAX_BONUSLEN);
    ASSERT(dn->dn_type == DMU_OT_NONE);
    ASSERT3U(dn->dn_maxblkid, ==, 0);
    ASSERT3U(dn->dn_allocated_txg, ==, 0);
    ASSERT3U(dn->dn_assigned_txg, ==, 0);
    ASSERT(refcount_is_zero(&dn->dn_tx_holds));
    ASSERT3U(refcount_count(&dn->dn_holds), <=, 1);
    ASSERT3P(list_head(&dn->dn_dbufs), ==, NULL);

    for (i = 0; i < TXG_SIZE; i++) {
        ASSERT3U(dn->dn_next_nlevels[i], ==, 0);
        ASSERT3U(dn->dn_next_indblkshift[i], ==, 0);
        ASSERT3U(dn->dn_dirtyblksz[i], ==, 0);
        ASSERT3P(list_head(&dn->dn_dirty_dbufs[i]), ==, NULL);
        ASSERT3U(avl_numnodes(&dn->dn_ranges[i]), ==, 0);
    }

    dn->dn_type = ot;
    dnode_setdblksz(dn, blocksize);
    dn->dn_indblkshift = ibs;
    dn->dn_nlevels = 1;
    dn->dn_nblkptr = 1 + ((DN_MAX_BONUSLEN - bonuslen) >> SPA_BLKPTRSHIFT);
    dn->dn_bonustype = bonustype;
    dn->dn_bonuslen = bonuslen;
    dn->dn_checksum = ZIO_CHECKSUM_INHERIT;
    dn->dn_compress = ZIO_COMPRESS_INHERIT;
    dn->dn_dirtyctx = 0;

    dn->dn_free_txg = 0;
    if (dn->dn_dirtyctx_firstset) {
        kmem_free(dn->dn_dirtyctx_firstset, 1);
        dn->dn_dirtyctx_firstset = NULL;
    }

    dn->dn_allocated_txg = tx->tx_txg;
    dnode_setdirty(dn, tx);
}

void
dnode_reallocate(dnode_t *dn, dmu_object_type_t ot, int blocksize,
    dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
{
    dmu_buf_impl_t *db = NULL;

    ASSERT3U(blocksize, >=, SPA_MINBLOCKSIZE);
    ASSERT3U(blocksize, <=, SPA_MAXBLOCKSIZE);
    ASSERT3U(blocksize % SPA_MINBLOCKSIZE, ==, 0);
    ASSERT3P(list_head(&dn->dn_dbufs), ==, NULL);
    ASSERT(!(dn->dn_object & DMU_PRIVATE_OBJECT) || dmu_tx_private_ok(tx));
    ASSERT(tx->tx_txg != 0);
    ASSERT((bonustype == DMU_OT_NONE && bonuslen == 0) ||
        (bonustype != DMU_OT_NONE && bonuslen != 0));
    ASSERT3U(bonustype, <, DMU_OT_NUMTYPES);
    ASSERT3U(bonuslen, <=, DN_MAX_BONUSLEN);
    ASSERT(dn->dn_dirtyblksz[0] == 0);
    ASSERT(dn->dn_dirtyblksz[1] == 0);
    ASSERT(dn->dn_dirtyblksz[2] == 0);
    ASSERT(dn->dn_dirtyblksz[3] == 0);

    /*
     * XXX I should really have a generation number to tell if we
     * need to do this...
     */
    if (blocksize != dn->dn_datablksz ||
        dn->dn_bonustype != bonustype || dn->dn_bonuslen != bonuslen) {
        /* free all old data */
        dnode_free_range(dn, 0, -1ULL, tx);
    }

    /* change blocksize */
    rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
    dnode_setdblksz(dn, blocksize);
    dnode_setdirty(dn, tx);
    /* don't need dd_dirty_mtx, dnode is already dirty */
    ASSERT(dn->dn_dirtyblksz[tx->tx_txg&TXG_MASK] != 0);
    dn->dn_dirtyblksz[tx->tx_txg&TXG_MASK] = blocksize;
    rw_exit(&dn->dn_struct_rwlock);

    /* change type */
    dn->dn_type = ot;

    if (dn->dn_bonuslen != bonuslen) {
        /* change bonus size */
        if (bonuslen == 0)
            bonuslen = 1; /* XXX */
        db = dbuf_hold_bonus(dn, FTAG);
        dbuf_read(db);
        mutex_enter(&db->db_mtx);
        ASSERT3U(db->db.db_size, ==, dn->dn_bonuslen);
        ASSERT(db->db.db_data != NULL);
        db->db.db_size = bonuslen;
        mutex_exit(&db->db_mtx);
        dbuf_dirty(db, tx);
    }

    /* change bonus size and type */
    mutex_enter(&dn->dn_mtx);
    dn->dn_bonustype = bonustype;
    dn->dn_bonuslen = bonuslen;
    dn->dn_nblkptr = 1 + ((DN_MAX_BONUSLEN - bonuslen) >> SPA_BLKPTRSHIFT);
    dn->dn_checksum = ZIO_CHECKSUM_INHERIT;
    dn->dn_compress = ZIO_COMPRESS_INHERIT;
    ASSERT3U(dn->dn_nblkptr, <=, DN_MAX_NBLKPTR);

    dn->dn_allocated_txg = tx->tx_txg;
    mutex_exit(&dn->dn_mtx);

    if (db)
        dbuf_remove_ref(db, FTAG);
}

void
dnode_special_close(dnode_t *dn)
{
    dnode_destroy(dn);
}

dnode_t *
dnode_special_open(objset_impl_t *os, dnode_phys_t *dnp, uint64_t object)
{
    dnode_t *dn = dnode_create(os, dnp, NULL, object);
    DNODE_VERIFY(dn);
    return (dn);
}

static void
dnode_buf_pageout(dmu_buf_t *db, void *arg)
{
    dnode_t **children_dnodes = arg;
    int i;
    int epb = db->db_size >> DNODE_SHIFT;

    for (i = 0; i < epb; i++) {
        dnode_t *dn = children_dnodes[i];
        int n;

        if (dn == NULL)
            continue;
#ifdef ZFS_DEBUG
        /*
         * If there are holds on this dnode, then there should
         * be holds on the dnode's containing dbuf as well; thus
         * it wouldn't be eligable for eviction and this function
         * would not have been called.
         */
        ASSERT(refcount_is_zero(&dn->dn_holds));
        ASSERT(list_head(&dn->dn_dbufs) == NULL);
        ASSERT(refcount_is_zero(&dn->dn_tx_holds));

        for (n = 0; n < TXG_SIZE; n++)
            ASSERT(dn->dn_dirtyblksz[n] == 0);
#endif
        children_dnodes[i] = NULL;
        dnode_destroy(dn);
    }
    kmem_free(children_dnodes, epb * sizeof (dnode_t *));
}

/*
 * Returns held dnode if the object number is valid, NULL if not.
 * Note that this will succeed even for free dnodes.
 */
dnode_t *
dnode_hold_impl(objset_impl_t *os, uint64_t object, int flag, void *ref)
{
    int epb, idx;
    int drop_struct_lock = FALSE;
    uint64_t blk;
    dnode_t *mdn, *dn;
    dmu_buf_impl_t *db;
    dnode_t **children_dnodes;

    if (object == 0 || object >= DN_MAX_OBJECT)
        return (NULL);

    mdn = os->os_meta_dnode;

    DNODE_VERIFY(mdn);

    if (!RW_WRITE_HELD(&mdn->dn_struct_rwlock)) {
        rw_enter(&mdn->dn_struct_rwlock, RW_READER);
        drop_struct_lock = TRUE;
    }

    blk = dbuf_whichblock(mdn, object * sizeof (dnode_phys_t));

    db = dbuf_hold(mdn, blk);
    if (drop_struct_lock)
        rw_exit(&mdn->dn_struct_rwlock);
    dbuf_read(db);

    ASSERT3U(db->db.db_size, >=, 1<<DNODE_SHIFT);
    epb = db->db.db_size >> DNODE_SHIFT;

    idx = object & (epb-1);

    children_dnodes = dmu_buf_get_user(&db->db);
    if (children_dnodes == NULL) {
        dnode_t **winner;
        children_dnodes = kmem_zalloc(epb * sizeof (dnode_t *),
            KM_SLEEP);
        if (winner = dmu_buf_set_user(&db->db, children_dnodes, NULL,
            dnode_buf_pageout)) {
            kmem_free(children_dnodes, epb * sizeof (dnode_t *));
            children_dnodes = winner;
        }
    }

    if ((dn = children_dnodes[idx]) == NULL) {
        dnode_t *winner;
        dn = dnode_create(os, (dnode_phys_t *)db->db.db_data+idx,
            db, object);
        winner = atomic_cas_ptr(&children_dnodes[idx], NULL, dn);
        if (winner != NULL) {
            dnode_destroy(dn);
            dn = winner;
        }
    }

    mutex_enter(&dn->dn_mtx);
    if (dn->dn_free_txg ||
        ((flag & DNODE_MUST_BE_ALLOCATED) && dn->dn_type == DMU_OT_NONE) ||
        ((flag & DNODE_MUST_BE_FREE) && dn->dn_type != DMU_OT_NONE)) {
        mutex_exit(&dn->dn_mtx);
        dbuf_rele(db);
        return (NULL);
    }
    mutex_exit(&dn->dn_mtx);

    if (refcount_add(&dn->dn_holds, ref) == 1)
        dbuf_add_ref(db, dn);

    DNODE_VERIFY(dn);
    ASSERT3P(dn->dn_dbuf, ==, db);
    ASSERT3U(dn->dn_object, ==, object);
    dbuf_rele(db);

    return (dn);
}

/*
 * Return held dnode if the object is allocated, NULL if not.
 */
dnode_t *
dnode_hold(objset_impl_t *os, uint64_t object, void *ref)
{
    return (dnode_hold_impl(os, object, DNODE_MUST_BE_ALLOCATED, ref));
}

void
dnode_add_ref(dnode_t *dn, void *ref)
{
    ASSERT(refcount_count(&dn->dn_holds) > 0);
    (void) refcount_add(&dn->dn_holds, ref);
}

void
dnode_rele(dnode_t *dn, void *ref)
{
    uint64_t refs;

    refs = refcount_remove(&dn->dn_holds, ref);
    /* NOTE: the DNODE_DNODE does not have a dn_dbuf */
    if (refs == 0 && dn->dn_dbuf)
        dbuf_remove_ref(dn->dn_dbuf, dn);
}

void
dnode_setdirty(dnode_t *dn, dmu_tx_t *tx)
{
    objset_impl_t *os = dn->dn_objset;
    uint64_t txg = tx->tx_txg;

    if (IS_DNODE_DNODE(dn->dn_object))
        return;

    DNODE_VERIFY(dn);

#ifdef ZFS_DEBUG
    mutex_enter(&dn->dn_mtx);
    ASSERT(dn->dn_phys->dn_type || dn->dn_allocated_txg);
    /* ASSERT(dn->dn_free_txg == 0 || dn->dn_free_txg >= txg); */
    mutex_exit(&dn->dn_mtx);
#endif

    mutex_enter(&os->os_lock);

    /*
     * If we are already marked dirty, we're done.
     */
    if (dn->dn_dirtyblksz[txg&TXG_MASK] > 0) {
        mutex_exit(&os->os_lock);
        return;
    }

    ASSERT(!refcount_is_zero(&dn->dn_holds) || list_head(&dn->dn_dbufs));
    ASSERT(dn->dn_datablksz != 0);
    dn->dn_dirtyblksz[txg&TXG_MASK] = dn->dn_datablksz;

    dprintf_ds(os->os_dsl_dataset, "obj=%llu txg=%llu\n",
        dn->dn_object, txg);

    if (dn->dn_free_txg > 0 && dn->dn_free_txg <= txg) {
        list_insert_tail(&os->os_free_dnodes[txg&TXG_MASK], dn);
    } else {
        list_insert_tail(&os->os_dirty_dnodes[txg&TXG_MASK], dn);
    }

    mutex_exit(&os->os_lock);

    /*
     * The dnode maintains a hold on its containing dbuf as
     * long as there are holds on it.  Each instantiated child
     * dbuf maintaines a hold on the dnode.  When the last child
     * drops its hold, the dnode will drop its hold on the
     * containing dbuf. We add a "dirty hold" here so that the
     * dnode will hang around after we finish processing its
     * children.
     */
    (void) refcount_add(&dn->dn_holds, (void *)(uintptr_t)tx->tx_txg);

    dbuf_dirty(dn->dn_dbuf, tx);

    dsl_dataset_dirty(os->os_dsl_dataset, tx);
}

void
dnode_free(dnode_t *dn, dmu_tx_t *tx)
{
    dprintf("dn=%p txg=%llu\n", dn, tx->tx_txg);

    /* we should be the only holder... hopefully */
    /* ASSERT3U(refcount_count(&dn->dn_holds), ==, 1); */

    mutex_enter(&dn->dn_mtx);
    if (dn->dn_type == DMU_OT_NONE || dn->dn_free_txg) {
        mutex_exit(&dn->dn_mtx);
        return;
    }
    dn->dn_free_txg = tx->tx_txg;
    mutex_exit(&dn->dn_mtx);

    /*
     * If the dnode is already dirty, it needs to be moved from
     * the dirty list to the free list.
     */
    mutex_enter(&dn->dn_objset->os_lock);
    if (dn->dn_dirtyblksz[tx->tx_txg&TXG_MASK] > 0) {
        list_remove(
            &dn->dn_objset->os_dirty_dnodes[tx->tx_txg&TXG_MASK], dn);
        list_insert_tail(
            &dn->dn_objset->os_free_dnodes[tx->tx_txg&TXG_MASK], dn);
        mutex_exit(&dn->dn_objset->os_lock);
    } else {
        mutex_exit(&dn->dn_objset->os_lock);
        dnode_setdirty(dn, tx);
    }
}

/*
 * Try to change the block size for the indicated dnode.  This can only
 * succeed if there are no blocks allocated or dirty beyond first block
 */
int
dnode_set_blksz(dnode_t *dn, uint64_t size, int ibs, dmu_tx_t *tx)
{
    dmu_buf_impl_t *db, *db_next;
    int have_db0 = FALSE;
    int err = ENOTSUP;

    if (size == 0)
        size = SPA_MINBLOCKSIZE;
    if (size > SPA_MAXBLOCKSIZE)
        size = SPA_MAXBLOCKSIZE;
    else
        size = P2ROUNDUP(size, SPA_MINBLOCKSIZE);

    if (ibs == 0)
        ibs = dn->dn_indblkshift;

    if (size >> SPA_MINBLOCKSHIFT == dn->dn_datablkszsec &&
        ibs == dn->dn_indblkshift)
        return (0);

    rw_enter(&dn->dn_struct_rwlock, RW_WRITER);

    /* Check for any allocated blocks beyond the first */
    if (dn->dn_phys->dn_maxblkid != 0)
        goto end;

    /*
     * Any buffers allocated for blocks beyond the first
     * must be evictable/evicted, because they're the wrong size.
     */
    mutex_enter(&dn->dn_dbufs_mtx);
    /*
     * Since we have the dn_dbufs_mtx, nothing can be
     * removed from dn_dbufs.  Since we have dn_struct_rwlock/w,
     * nothing can be added to dn_dbufs.
     */
    for (db = list_head(&dn->dn_dbufs); db; db = db_next) {
        db_next = list_next(&dn->dn_dbufs, db);

        if (db->db_blkid == 0) {
            have_db0 = TRUE;
        } else if (db->db_blkid != DB_BONUS_BLKID) {
            mutex_exit(&dn->dn_dbufs_mtx);
            goto end;
        }
    }
    mutex_exit(&dn->dn_dbufs_mtx);

    /* Fast-track if there is no data in the file */
    if (BP_IS_HOLE(&dn->dn_phys->dn_blkptr[0]) && !have_db0) {
        dnode_setdblksz(dn, size);
        dn->dn_indblkshift = ibs;
        dnode_setdirty(dn, tx);
        /* don't need dd_dirty_mtx, dnode is already dirty */
        dn->dn_dirtyblksz[tx->tx_txg&TXG_MASK] = size;
        dn->dn_next_indblkshift[tx->tx_txg&TXG_MASK] = ibs;
        rw_exit(&dn->dn_struct_rwlock);
        return (0);
    }

    /* obtain the old block */
    db = dbuf_hold(dn, 0);

    dbuf_new_size(db, size, tx);

    dnode_setdblksz(dn, size);
    dn->dn_indblkshift = ibs;
    /* don't need dd_dirty_mtx, dnode is already dirty */
    dn->dn_dirtyblksz[tx->tx_txg&TXG_MASK] = size;
    dn->dn_next_indblkshift[tx->tx_txg&TXG_MASK] = ibs;
    dbuf_rele(db);

    err = 0;
end:
    rw_exit(&dn->dn_struct_rwlock);
    return (err);
}

uint64_t
dnode_max_nonzero_offset(dnode_t *dn)
{
    if (dn->dn_phys->dn_maxblkid == 0 &&
        BP_IS_HOLE(&dn->dn_phys->dn_blkptr[0]))
        return (0);
    else
        return ((dn->dn_phys->dn_maxblkid+1) * dn->dn_datablksz);
}

void
dnode_new_blkid(dnode_t *dn, uint64_t blkid, dmu_tx_t *tx)
{
    uint64_t txgoff = tx->tx_txg & TXG_MASK;
    int drop_struct_lock = FALSE;
    int epbs, old_nlevels, new_nlevels;
    uint64_t sz;

    if (blkid == DB_BONUS_BLKID)
        return;

    if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
        rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
        drop_struct_lock = TRUE;
    }

    if (blkid > dn->dn_maxblkid)
        dn->dn_maxblkid = blkid;

    /*
     * Compute the number of levels necessary to support the
     * new blkid.
     */
    new_nlevels = 1;
    epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;

    for (sz = dn->dn_nblkptr; sz <= blkid && sz >= dn->dn_nblkptr;
        sz <<= epbs)
        new_nlevels++;
    old_nlevels = dn->dn_nlevels;

    if (new_nlevels > dn->dn_next_nlevels[txgoff])
        dn->dn_next_nlevels[txgoff] = new_nlevels;

    if (new_nlevels > old_nlevels) {
        dprintf("dn %p increasing nlevels from %u to %u\n",
            dn, dn->dn_nlevels, new_nlevels);
        dn->dn_nlevels = new_nlevels;
    }

    /*
     * Dirty the left indirects.
     * Note: the caller should have just dnode_use_space()'d one
     * data block's worth, so we could subtract that out of
     * dn_inflight_data to determine if there is any dirty data
     * besides this block.
     * We don't strictly need to dirty them unless there's
     * *something* in the object (eg. on disk or dirty)...
     */
    if (new_nlevels > old_nlevels) {
        dmu_buf_impl_t *db = dbuf_hold_level(dn, old_nlevels, 0, FTAG);
        dprintf("dn %p dirtying left indirects\n", dn);
        dbuf_dirty(db, tx);
        dbuf_remove_ref(db, FTAG);
    }
#ifdef ZFS_DEBUG
    else if (old_nlevels > 1 && new_nlevels > old_nlevels) {
        dmu_buf_impl_t *db;
        int i;

        for (i = 0; i < dn->dn_nblkptr; i++) {
            db = dbuf_hold_level(dn, old_nlevels-1, i, FTAG);
            ASSERT(!
                list_link_active(&db->db_dirty_node[txgoff]));
            dbuf_remove_ref(db, FTAG);
        }
    }
#endif

    dprintf("dn %p done\n", dn);

out:
    if (drop_struct_lock)
        rw_exit(&dn->dn_struct_rwlock);
}

void
dnode_clear_range(dnode_t *dn, uint64_t blkid, uint64_t nblks, dmu_tx_t *tx)
{
    avl_tree_t *tree = &dn->dn_ranges[tx->tx_txg&TXG_MASK];
    avl_index_t where;
    free_range_t *rp;
    free_range_t rp_tofind;
    uint64_t endblk = blkid + nblks;

    ASSERT(MUTEX_HELD(&dn->dn_mtx));
    ASSERT(nblks <= UINT64_MAX - blkid); /* no overflow */

    dprintf_dnode(dn, "blkid=%llu nblks=%llu txg=%llu\n",
        blkid, nblks, tx->tx_txg);
    rp_tofind.fr_blkid = blkid;
    rp = avl_find(tree, &rp_tofind, &where);
    if (rp == NULL)
        rp = avl_nearest(tree, where, AVL_BEFORE);
    if (rp == NULL)
        rp = avl_nearest(tree, where, AVL_AFTER);

    while (rp && (rp->fr_blkid <= blkid + nblks)) {
        uint64_t fr_endblk = rp->fr_blkid + rp->fr_nblks;
        free_range_t *nrp = AVL_NEXT(tree, rp);

        if (blkid <= rp->fr_blkid && endblk >= fr_endblk) {
            /* clear this entire range */
            avl_remove(tree, rp);
            kmem_free(rp, sizeof (free_range_t));
        } else if (blkid <= rp->fr_blkid &&
            endblk > rp->fr_blkid && endblk < fr_endblk) {
            /* clear the beginning of this range */
            rp->fr_blkid = endblk;
            rp->fr_nblks = fr_endblk - endblk;
        } else if (blkid > rp->fr_blkid && blkid < fr_endblk &&
            endblk >= fr_endblk) {
            /* clear the end of this range */
            rp->fr_nblks = blkid - rp->fr_blkid;
        } else if (blkid > rp->fr_blkid && endblk < fr_endblk) {
            /* clear a chunk out of this range */
            free_range_t *new_rp =
                kmem_alloc(sizeof (free_range_t), KM_SLEEP);

            new_rp->fr_blkid = endblk;
            new_rp->fr_nblks = fr_endblk - endblk;
            avl_insert_here(tree, new_rp, rp, AVL_AFTER);
            rp->fr_nblks = blkid - rp->fr_blkid;
        }
        /* there may be no overlap */
        rp = nrp;
    }
}

void
dnode_free_range(dnode_t *dn, uint64_t off, uint64_t len, dmu_tx_t *tx)
{
    dmu_buf_impl_t *db;
    uint64_t start, objsize, blkid, nblks;
    int blkshift, blksz, tail, head, epbs;
    int trunc = FALSE;

    rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
    blksz = dn->dn_datablksz;
    blkshift = dn->dn_datablkshift;
    epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;

    /* If the range is past the end of the file, this is a no-op */
    objsize = blksz * (dn->dn_maxblkid+1);
    if (off >= objsize)
        goto out;
    if (len == -1ULL) {
        len = UINT64_MAX - off;
        trunc = TRUE;
    }

    /*
     * First, block align the region to free:
     */
    if (dn->dn_maxblkid == 0) {
        if (off == 0) {
            head = 0;
        } else {
            head = blksz - off;
            ASSERT3U(head, >, 0);
        }
        start = off;
    } else {
        ASSERT(ISP2(blksz));
        head = P2NPHASE(off, blksz);
        start = P2PHASE(off, blksz);
    }
    /* zero out any partial block data at the start of the range */
    if (head) {
        ASSERT3U(start + head, ==, blksz);
        if (len < head)
            head = len;
        if (dbuf_hold_impl(dn, 0, dbuf_whichblock(dn, off), TRUE,
            FTAG, &db) == 0) {
            caddr_t data;

            /* don't dirty if it isn't on disk and isn't dirty */
            if (db->db_dirtied ||
                (db->db_blkptr && !BP_IS_HOLE(db->db_blkptr))) {
                rw_exit(&dn->dn_struct_rwlock);
                dbuf_will_dirty(db, tx);
                rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
                data = db->db.db_data;
                bzero(data + start, head);
            }
            dbuf_remove_ref(db, FTAG);
        }
        off += head;
        len -= head;
    }
    /* If the range was less than one block, we are done */
    if (len == 0)
        goto out;

    /* If the remaining range is past the end of the file, we are done */
    if (off > dn->dn_maxblkid << blkshift)
        goto out;

    if (off + len == UINT64_MAX)
        tail = 0;
    else
        tail = P2PHASE(len, blksz);

    ASSERT3U(P2PHASE(off, blksz), ==, 0);
    /* zero out any partial block data at the end of the range */
    if (tail) {
        if (len < tail)
            tail = len;
        if (dbuf_hold_impl(dn, 0, dbuf_whichblock(dn, off+len),
            TRUE, FTAG, &db) == 0) {
            /* don't dirty if it isn't on disk and isn't dirty */
            if (db->db_dirtied ||
                (db->db_blkptr && !BP_IS_HOLE(db->db_blkptr))) {
                rw_exit(&dn->dn_struct_rwlock);
                dbuf_will_dirty(db, tx);
                rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
                bzero(db->db.db_data, tail);
            }
            dbuf_remove_ref(db, FTAG);
        }
        len -= tail;
    }
    /* If the range did not include a full block, we are done */
    if (len == 0)
        goto out;

    /* dirty the left indirects */
    if (dn->dn_nlevels > 1 && off != 0) {
        db = dbuf_hold_level(dn, 1,
            (off - head) >> (blkshift + epbs), FTAG);
        dbuf_will_dirty(db, tx);
        dbuf_remove_ref(db, FTAG);
    }

    /* dirty the right indirects */
    if (dn->dn_nlevels > 1 && !trunc) {
        db = dbuf_hold_level(dn, 1,
            (off + len + tail - 1) >> (blkshift + epbs), FTAG);
        dbuf_will_dirty(db, tx);
        dbuf_remove_ref(db, FTAG);
    }

    /*
     * Finally, add this range to the dnode range list, we
     * will finish up this free operation in the syncing phase.
     */
    ASSERT(IS_P2ALIGNED(off, 1<<blkshift));
    ASSERT(off + len == UINT64_MAX || IS_P2ALIGNED(len, 1<<blkshift));
    blkid = off >> blkshift;
    nblks = len >> blkshift;

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

    mutex_enter(&dn->dn_mtx);
    dnode_clear_range(dn, blkid, nblks, tx);
    {
        free_range_t *rp, *found;
        avl_index_t where;
        avl_tree_t *tree = &dn->dn_ranges[tx->tx_txg&TXG_MASK];

        /* Add new range to dn_ranges */
        rp = kmem_alloc(sizeof (free_range_t), KM_SLEEP);
        rp->fr_blkid = blkid;
        rp->fr_nblks = nblks;
        found = avl_find(tree, rp, &where);
        ASSERT(found == NULL);
        avl_insert(tree, rp, where);
        dprintf_dnode(dn, "blkid=%llu nblks=%llu txg=%llu\n",
            blkid, nblks, tx->tx_txg);
    }
    mutex_exit(&dn->dn_mtx);

    dbuf_free_range(dn, blkid, nblks, tx);
    dnode_setdirty(dn, tx);
out:
    rw_exit(&dn->dn_struct_rwlock);
}

/* return TRUE if this blkid was freed in a recent txg, or FALSE if it wasn't */
uint64_t
dnode_block_freed(dnode_t *dn, uint64_t blkid)
{
    free_range_t range_tofind;
    void *dp = spa_get_dsl(dn->dn_objset->os_spa);
    int i;

    if (blkid == DB_BONUS_BLKID)
        return (FALSE);

    /*
     * If we're in the process of opening the pool, dp will not be
     * set yet, but there shouldn't be anything dirty.
     */
    if (dp == NULL)
        return (FALSE);

    if (dn->dn_free_txg)
        return (TRUE);

    /*
     * If dn_datablkshift is not set, then there's only a single
     * block, in which case there will never be a free range so it
     * won't matter.
     */
    range_tofind.fr_blkid = blkid;
    mutex_enter(&dn->dn_mtx);
    for (i = 0; i < TXG_SIZE; i++) {
        free_range_t *range_found;
        avl_index_t idx;

        range_found = avl_find(&dn->dn_ranges[i], &range_tofind, &idx);
        if (range_found) {
            ASSERT(range_found->fr_nblks > 0);
            break;
        }
        range_found = avl_nearest(&dn->dn_ranges[i], idx, AVL_BEFORE);
        if (range_found &&
            range_found->fr_blkid + range_found->fr_nblks > blkid)
            break;
    }
    mutex_exit(&dn->dn_mtx);
    return (i < TXG_SIZE);
}

/* call from syncing context when we actually write/free space for this dnode */
void
dnode_diduse_space(dnode_t *dn, int64_t space)
{
    uint64_t sectors;

    dprintf_dnode(dn, "dn=%p dnp=%p secphys=%llu space=%lld\n",
        dn, dn->dn_phys,
        (u_longlong_t)dn->dn_phys->dn_secphys,
        (longlong_t)space);

    ASSERT(P2PHASE(space, 1<<DEV_BSHIFT) == 0);

    mutex_enter(&dn->dn_mtx);
    if (space > 0) {
        sectors = space >> DEV_BSHIFT;
        ASSERT3U(dn->dn_phys->dn_secphys + sectors, >=,
            dn->dn_phys->dn_secphys);
        dn->dn_phys->dn_secphys += sectors;
    } else {
        sectors = -space >> DEV_BSHIFT;
        ASSERT3U(dn->dn_phys->dn_secphys, >=, sectors);
        dn->dn_phys->dn_secphys -= sectors;
    }
    mutex_exit(&dn->dn_mtx);
}

/*
 * Call when we think we're going to write/free space in open context.
 * Be conservative (ie. OK to write less than this or free more than
 * this, but don't write more or free less).
 */
void
dnode_willuse_space(dnode_t *dn, int64_t space, dmu_tx_t *tx)
{
    objset_impl_t *os = dn->dn_objset;
    dsl_dataset_t *ds = os->os_dsl_dataset;

    if (space > 0)
        space = spa_get_asize(os->os_spa, space);

    if (ds)
        dsl_dir_willuse_space(ds->ds_dir, space, tx);

    dmu_tx_willuse_space(tx, space);
}

static int
dnode_next_offset_level(dnode_t *dn, boolean_t hole, uint64_t *offset,
    int lvl, uint64_t blkfill)
{
    dmu_buf_impl_t *db = NULL;
    void *data = NULL;
    uint64_t epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
    uint64_t epb = 1ULL << epbs;
    uint64_t minfill, maxfill;
    int i, error, span;

    dprintf("probing object %llu offset %llx level %d of %u\n",
        dn->dn_object, *offset, lvl, dn->dn_phys->dn_nlevels);

    if (lvl == dn->dn_phys->dn_nlevels) {
        error = 0;
        epb = dn->dn_phys->dn_nblkptr;
        data = dn->dn_phys->dn_blkptr;
    } else {
        uint64_t blkid = dbuf_whichblock(dn, *offset) >> (epbs * lvl);
        error = dbuf_hold_impl(dn, lvl, blkid, TRUE, FTAG, &db);
        if (error) {
            if (error == ENOENT)
                return (hole ? 0 : ESRCH);
            return (error);
        }
        dbuf_read_havestruct(db);
        data = db->db.db_data;
    }

    if (lvl == 0) {
        dnode_phys_t *dnp = data;
        span = DNODE_SHIFT;
        ASSERT(dn->dn_type == DMU_OT_DNODE);

        for (i = (*offset >> span) & (blkfill - 1); i < blkfill; i++) {
            if (!dnp[i].dn_type == hole)
                break;
            *offset += 1ULL << span;
        }
        if (i == blkfill)
            error = ESRCH;
    } else {
        blkptr_t *bp = data;
        span = (lvl - 1) * epbs + dn->dn_datablkshift;
        minfill = 0;
        maxfill = blkfill << ((lvl - 1) * epbs);

        if (hole)
            maxfill--;
        else
            minfill++;

        for (i = (*offset >> span) & ((1ULL << epbs) - 1);
            i < epb; i++) {
            if (bp[i].blk_fill >= minfill &&
                bp[i].blk_fill <= maxfill)
                break;
            *offset += 1ULL << span;
        }
        if (i >= epb)
            error = ESRCH;
    }

    if (db)
        dbuf_remove_ref(db, FTAG);

    return (error);
}

/*
 * Find the next hole, data, or sparse region at or after *offset.
 * The value 'blkfill' tells us how many items we expect to find
 * in an L0 data block; this value is 1 for normal objects,
 * DNODES_PER_BLOCK for the meta dnode, and some fraction of
 * DNODES_PER_BLOCK when searching for sparse regions thereof.
 * Examples:
 *
 * dnode_next_offset(dn, hole, offset, 1, 1);
 *  Finds the next hole/data in a file.
 *  Used in dmu_offset_next().
 *
 * dnode_next_offset(mdn, hole, offset, 0, DNODES_PER_BLOCK);
 *  Finds the next free/allocated dnode an objset's meta-dnode.
 *  Used in dmu_object_next().
 *
 * dnode_next_offset(mdn, TRUE, offset, 2, DNODES_PER_BLOCK >> 2);
 *  Finds the next L2 meta-dnode bp that's at most 1/4 full.
 *  Used in dmu_object_alloc().
 */
int
dnode_next_offset(dnode_t *dn, boolean_t hole, uint64_t *offset,
    int minlvl, uint64_t blkfill)
{
    int lvl, maxlvl;
    int error = 0;
    uint64_t initial_offset = *offset;

    rw_enter(&dn->dn_struct_rwlock, RW_READER);

    if (dn->dn_phys->dn_nlevels == 0) {
        rw_exit(&dn->dn_struct_rwlock);
        return (ESRCH);
    }

    if (dn->dn_datablkshift == 0) {
        if (*offset < dn->dn_datablksz) {
            if (hole)
                *offset = dn->dn_datablksz;
        } else {
            error = ESRCH;
        }
        rw_exit(&dn->dn_struct_rwlock);
        return (error);
    }

    maxlvl = dn->dn_phys->dn_nlevels;

    for (lvl = minlvl; lvl <= maxlvl; lvl++) {
        error = dnode_next_offset_level(dn, hole, offset, lvl, blkfill);
        if (error == 0)
            break;
    }

    while (--lvl >= minlvl && error == 0)
        error = dnode_next_offset_level(dn, hole, offset, lvl, blkfill);

    rw_exit(&dn->dn_struct_rwlock);

    if (initial_offset > *offset)
        return (ESRCH);

    return (error);
}