/*
 * 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.
 *
 * Portions Copyright 2010 Robert Milkowski
 *
 * Copyright 2017 Nexenta Systems, Inc.  All rights reserved.
 * Copyright (c) 2012, 2020 by Delphix. All rights reserved.
 * Copyright (c) 2014 Integros [integros.com]
 * Copyright 2019 Joyent, Inc.
 */

/*
 * ZFS volume emulation driver.
 *
 * Makes a DMU object look like a volume of arbitrary size, up to 2^64 bytes.
 * Volumes are accessed through the symbolic links named:
 *
 * /dev/zvol/dsk/<pool_name>/<dataset_name>
 * /dev/zvol/rdsk/<pool_name>/<dataset_name>
 *
 * These links are created by the /dev filesystem (sdev_zvolops.c).
 * Volumes are persistent through reboot.  No user command needs to be
 * run before opening and using a device.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/errno.h>
#include <sys/uio.h>
#include <sys/buf.h>
#include <sys/modctl.h>
#include <sys/open.h>
#include <sys/kmem.h>
#include <sys/conf.h>
#include <sys/cmn_err.h>
#include <sys/stat.h>
#include <sys/zap.h>
#include <sys/spa.h>
#include <sys/spa_impl.h>
#include <sys/zio.h>
#include <sys/dmu_traverse.h>
#include <sys/dnode.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_prop.h>
#include <sys/dkio.h>
#include <sys/efi_partition.h>
#include <sys/byteorder.h>
#include <sys/pathname.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#include <sys/crc32.h>
#include <sys/dirent.h>
#include <sys/policy.h>
#include <sys/fs/zfs.h>
#include <sys/zfs_ioctl.h>
#include <sys/mkdev.h>
#include <sys/zil.h>
#include <sys/refcount.h>
#include <sys/zfs_znode.h>
#include <sys/zfs_rlock.h>
#include <sys/vdev_impl.h>
#include <sys/zvol.h>
#include <sys/dumphdr.h>
#include <sys/zil_impl.h>
#include <sys/dbuf.h>
#include <sys/dmu_tx.h>
#include <sys/zfeature.h>
#include <sys/zio_checksum.h>
#include <sys/zil_impl.h>
#include <sys/smt.h>
#include <sys/dkioc_free_util.h>
#include <sys/zfs_rlock.h>

#include "zfs_namecheck.h"

void *zfsdev_state;
static char *zvol_tag = "zvol_tag";

#define ZVOL_DUMPSIZE           "dumpsize"

/*
 * This lock protects the zfsdev_state structure from being modified
 * while it's being used, e.g. an open that comes in before a create
 * finishes.  It also protects temporary opens of the dataset so that,
 * e.g., an open doesn't get a spurious EBUSY.
 */
kmutex_t zfsdev_state_lock;
static uint32_t zvol_minors;

typedef struct zvol_extent {
        list_node_t     ze_node;
        dva_t           ze_dva;         /* dva associated with this extent */
        uint64_t        ze_nblks;       /* number of blocks in extent */
} zvol_extent_t;

/*
 * The in-core state of each volume.
 */
typedef struct zvol_state {
        char            zv_name[MAXPATHLEN]; /* pool/dd name */
        uint64_t        zv_volsize;     /* amount of space we advertise */
        uint64_t        zv_volblocksize; /* volume block size */
        minor_t         zv_minor;       /* minor number */
        uint8_t         zv_min_bs;      /* minimum addressable block shift */
        uint8_t         zv_flags;       /* readonly, dumpified, etc. */
        objset_t        *zv_objset;     /* objset handle */
        uint32_t        zv_open_count[OTYPCNT]; /* open counts */
        uint32_t        zv_total_opens; /* total open count */
        zilog_t         *zv_zilog;      /* ZIL handle */
        list_t          zv_extents;     /* List of extents for dump */
        rangelock_t     zv_rangelock;
        dnode_t         *zv_dn;         /* dnode hold */
} zvol_state_t;

/*
 * zvol specific flags
 */
#define ZVOL_RDONLY     0x1
#define ZVOL_DUMPIFIED  0x2
#define ZVOL_EXCL       0x4
#define ZVOL_WCE        0x8

/*
 * zvol maximum transfer in one DMU tx.
 */
int zvol_maxphys = DMU_MAX_ACCESS/2;

/*
 * Toggle unmap functionality.
 */
boolean_t zvol_unmap_enabled = B_TRUE;

/*
 * If true, unmaps requested as synchronous are executed synchronously,
 * otherwise all unmaps are asynchronous.
 */
boolean_t zvol_unmap_sync_enabled = B_FALSE;

extern int zfs_set_prop_nvlist(const char *, zprop_source_t,
    nvlist_t *, nvlist_t *);
static int zvol_remove_zv(zvol_state_t *);
static int zvol_get_data(void *arg, lr_write_t *lr, char *buf,
    struct lwb *lwb, zio_t *zio);
static int zvol_dumpify(zvol_state_t *zv);
static int zvol_dump_fini(zvol_state_t *zv);
static int zvol_dump_init(zvol_state_t *zv, boolean_t resize);

static void
zvol_size_changed(zvol_state_t *zv, uint64_t volsize)
{
        dev_t dev = makedevice(ddi_driver_major(zfs_dip), zv->zv_minor);

        zv->zv_volsize = volsize;
        VERIFY(ddi_prop_update_int64(dev, zfs_dip,
            "Size", volsize) == DDI_SUCCESS);
        VERIFY(ddi_prop_update_int64(dev, zfs_dip,
            "Nblocks", lbtodb(volsize)) == DDI_SUCCESS);

        /* Notify specfs to invalidate the cached size */
        spec_size_invalidate(dev, VBLK);
        spec_size_invalidate(dev, VCHR);
}

int
zvol_check_volsize(uint64_t volsize, uint64_t blocksize)
{
        if (volsize == 0)
                return (SET_ERROR(EINVAL));

        if (volsize % blocksize != 0)
                return (SET_ERROR(EINVAL));

#ifdef _ILP32
        if (volsize - 1 > SPEC_MAXOFFSET_T)
                return (SET_ERROR(EOVERFLOW));
#endif
        return (0);
}

int
zvol_check_volblocksize(uint64_t volblocksize)
{
        if (volblocksize < SPA_MINBLOCKSIZE ||
            volblocksize > SPA_OLD_MAXBLOCKSIZE ||
            !ISP2(volblocksize))
                return (SET_ERROR(EDOM));

        return (0);
}

int
zvol_get_stats(objset_t *os, nvlist_t *nv)
{
        int error;
        dmu_object_info_t doi;
        uint64_t val;

        error = zap_lookup(os, ZVOL_ZAP_OBJ, "size", 8, 1, &val);
        if (error)
                return (error);

        dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_VOLSIZE, val);

        error = dmu_object_info(os, ZVOL_OBJ, &doi);

        if (error == 0) {
                dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_VOLBLOCKSIZE,
                    doi.doi_data_block_size);
        }

        return (error);
}

static zvol_state_t *
zvol_minor_lookup(const char *name)
{
        minor_t minor;
        zvol_state_t *zv;

        ASSERT(MUTEX_HELD(&zfsdev_state_lock));

        for (minor = 1; minor <= ZFSDEV_MAX_MINOR; minor++) {
                zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
                if (zv == NULL)
                        continue;
                if (strcmp(zv->zv_name, name) == 0)
                        return (zv);
        }

        return (NULL);
}

/* extent mapping arg */
struct maparg {
        zvol_state_t    *ma_zv;
        uint64_t        ma_blks;
};

/*ARGSUSED*/
static int
zvol_map_block(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
    const zbookmark_phys_t *zb, const dnode_phys_t *dnp, void *arg)
{
        struct maparg *ma = arg;
        zvol_extent_t *ze;
        int bs = ma->ma_zv->zv_volblocksize;

        if (bp == NULL || BP_IS_HOLE(bp) ||
            zb->zb_object != ZVOL_OBJ || zb->zb_level != 0)
                return (0);

        VERIFY(!BP_IS_EMBEDDED(bp));

        VERIFY3U(ma->ma_blks, ==, zb->zb_blkid);
        ma->ma_blks++;

        /* Abort immediately if we have encountered gang blocks */
        if (BP_IS_GANG(bp))
                return (SET_ERROR(EFRAGS));

        /*
         * See if the block is at the end of the previous extent.
         */
        ze = list_tail(&ma->ma_zv->zv_extents);
        if (ze &&
            DVA_GET_VDEV(BP_IDENTITY(bp)) == DVA_GET_VDEV(&ze->ze_dva) &&
            DVA_GET_OFFSET(BP_IDENTITY(bp)) ==
            DVA_GET_OFFSET(&ze->ze_dva) + ze->ze_nblks * bs) {
                ze->ze_nblks++;
                return (0);
        }

        dprintf_bp(bp, "%s", "next blkptr:");

        /* start a new extent */
        ze = kmem_zalloc(sizeof (zvol_extent_t), KM_SLEEP);
        ze->ze_dva = bp->blk_dva[0];    /* structure assignment */
        ze->ze_nblks = 1;
        list_insert_tail(&ma->ma_zv->zv_extents, ze);
        return (0);
}

static void
zvol_free_extents(zvol_state_t *zv)
{
        zvol_extent_t *ze;

        while (ze = list_head(&zv->zv_extents)) {
                list_remove(&zv->zv_extents, ze);
                kmem_free(ze, sizeof (zvol_extent_t));
        }
}

static int
zvol_get_lbas(zvol_state_t *zv)
{
        objset_t *os = zv->zv_objset;
        struct maparg   ma;
        int             err;

        ma.ma_zv = zv;
        ma.ma_blks = 0;
        zvol_free_extents(zv);

        /* commit any in-flight changes before traversing the dataset */
        txg_wait_synced(dmu_objset_pool(os), 0);
        err = traverse_dataset(dmu_objset_ds(os), 0,
            TRAVERSE_PRE | TRAVERSE_PREFETCH_METADATA, zvol_map_block, &ma);
        if (err || ma.ma_blks != (zv->zv_volsize / zv->zv_volblocksize)) {
                zvol_free_extents(zv);
                return (err ? err : EIO);
        }

        return (0);
}

/* ARGSUSED */
void
zvol_create_cb(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx)
{
        zfs_creat_t *zct = arg;
        nvlist_t *nvprops = zct->zct_props;
        int error;
        uint64_t volblocksize, volsize;

        VERIFY(nvlist_lookup_uint64(nvprops,
            zfs_prop_to_name(ZFS_PROP_VOLSIZE), &volsize) == 0);
        if (nvlist_lookup_uint64(nvprops,
            zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), &volblocksize) != 0)
                volblocksize = zfs_prop_default_numeric(ZFS_PROP_VOLBLOCKSIZE);

        /*
         * These properties must be removed from the list so the generic
         * property setting step won't apply to them.
         */
        VERIFY(nvlist_remove_all(nvprops,
            zfs_prop_to_name(ZFS_PROP_VOLSIZE)) == 0);
        (void) nvlist_remove_all(nvprops,
            zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE));

        error = dmu_object_claim(os, ZVOL_OBJ, DMU_OT_ZVOL, volblocksize,
            DMU_OT_NONE, 0, tx);
        ASSERT(error == 0);

        error = zap_create_claim(os, ZVOL_ZAP_OBJ, DMU_OT_ZVOL_PROP,
            DMU_OT_NONE, 0, tx);
        ASSERT(error == 0);

        error = zap_update(os, ZVOL_ZAP_OBJ, "size", 8, 1, &volsize, tx);
        ASSERT(error == 0);
}

/*
 * Replay a TX_TRUNCATE ZIL transaction if asked.  TX_TRUNCATE is how we
 * implement DKIOCFREE/free-long-range.
 */
static int
zvol_replay_truncate(void *arg1, void *arg2, boolean_t byteswap)
{
        zvol_state_t *zv = arg1;
        lr_truncate_t *lr = arg2;
        uint64_t offset, length;

        if (byteswap)
                byteswap_uint64_array(lr, sizeof (*lr));

        offset = lr->lr_offset;
        length = lr->lr_length;

        return (dmu_free_long_range(zv->zv_objset, ZVOL_OBJ, offset, length));
}

/*
 * Replay a TX_WRITE ZIL transaction that didn't get committed
 * after a system failure
 */
/* ARGSUSED */
static int
zvol_replay_write(void *arg1, void *arg2, boolean_t byteswap)
{
        zvol_state_t *zv = arg1;
        lr_write_t *lr = arg2;
        objset_t *os = zv->zv_objset;
        char *data = (char *)(lr + 1);  /* data follows lr_write_t */
        uint64_t offset, length;
        dmu_tx_t *tx;
        int error;

        if (byteswap)
                byteswap_uint64_array(lr, sizeof (*lr));

        offset = lr->lr_offset;
        length = lr->lr_length;

        /* If it's a dmu_sync() block, write the whole block */
        if (lr->lr_common.lrc_reclen == sizeof (lr_write_t)) {
                uint64_t blocksize = BP_GET_LSIZE(&lr->lr_blkptr);
                if (length < blocksize) {
                        offset -= offset % blocksize;
                        length = blocksize;
                }
        }

        tx = dmu_tx_create(os);
        dmu_tx_hold_write(tx, ZVOL_OBJ, offset, length);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
        } else {
                dmu_write(os, ZVOL_OBJ, offset, length, data, tx);
                dmu_tx_commit(tx);
        }

        return (error);
}

/* ARGSUSED */
static int
zvol_replay_err(void *arg1, void *arg2, boolean_t byteswap)
{
        return (SET_ERROR(ENOTSUP));
}

/*
 * Callback vectors for replaying records.
 * Only TX_WRITE and TX_TRUNCATE are needed for zvol.
 */
zil_replay_func_t *zvol_replay_vector[TX_MAX_TYPE] = {
        zvol_replay_err,        /* 0 no such transaction type */
        zvol_replay_err,        /* TX_CREATE */
        zvol_replay_err,        /* TX_MKDIR */
        zvol_replay_err,        /* TX_MKXATTR */
        zvol_replay_err,        /* TX_SYMLINK */
        zvol_replay_err,        /* TX_REMOVE */
        zvol_replay_err,        /* TX_RMDIR */
        zvol_replay_err,        /* TX_LINK */
        zvol_replay_err,        /* TX_RENAME */
        zvol_replay_write,      /* TX_WRITE */
        zvol_replay_truncate,   /* TX_TRUNCATE */
        zvol_replay_err,        /* TX_SETATTR */
        zvol_replay_err,        /* TX_ACL */
        zvol_replay_err,        /* TX_CREATE_ACL */
        zvol_replay_err,        /* TX_CREATE_ATTR */
        zvol_replay_err,        /* TX_CREATE_ACL_ATTR */
        zvol_replay_err,        /* TX_MKDIR_ACL */
        zvol_replay_err,        /* TX_MKDIR_ATTR */
        zvol_replay_err,        /* TX_MKDIR_ACL_ATTR */
        zvol_replay_err,        /* TX_WRITE2 */
};

int
zvol_name2minor(const char *name, minor_t *minor)
{
        zvol_state_t *zv;

        mutex_enter(&zfsdev_state_lock);
        zv = zvol_minor_lookup(name);
        if (minor && zv)
                *minor = zv->zv_minor;
        mutex_exit(&zfsdev_state_lock);
        return (zv ? 0 : -1);
}

/*
 * Create a minor node (plus a whole lot more) for the specified volume.
 */
int
zvol_create_minor(const char *name)
{
        zfs_soft_state_t *zs;
        zvol_state_t *zv;
        objset_t *os;
        dmu_object_info_t doi;
        minor_t minor = 0;
        char chrbuf[30], blkbuf[30];
        int error;

        mutex_enter(&zfsdev_state_lock);

        if (zvol_minor_lookup(name) != NULL) {
                mutex_exit(&zfsdev_state_lock);
                return (SET_ERROR(EEXIST));
        }

        /* lie and say we're read-only */
        error = dmu_objset_own(name, DMU_OST_ZVOL, B_TRUE, B_TRUE, FTAG, &os);

        if (error) {
                mutex_exit(&zfsdev_state_lock);
                return (error);
        }

        if ((minor = zfsdev_minor_alloc()) == 0) {
                dmu_objset_disown(os, 1, FTAG);
                mutex_exit(&zfsdev_state_lock);
                return (SET_ERROR(ENXIO));
        }

        if (ddi_soft_state_zalloc(zfsdev_state, minor) != DDI_SUCCESS) {
                dmu_objset_disown(os, 1, FTAG);
                mutex_exit(&zfsdev_state_lock);
                return (SET_ERROR(EAGAIN));
        }
        (void) ddi_prop_update_string(minor, zfs_dip, ZVOL_PROP_NAME,
            (char *)name);

        (void) snprintf(chrbuf, sizeof (chrbuf), "%u,raw", minor);

        if (ddi_create_minor_node(zfs_dip, chrbuf, S_IFCHR,
            minor, DDI_PSEUDO, 0) == DDI_FAILURE) {
                ddi_soft_state_free(zfsdev_state, minor);
                dmu_objset_disown(os, 1, FTAG);
                mutex_exit(&zfsdev_state_lock);
                return (SET_ERROR(EAGAIN));
        }

        (void) snprintf(blkbuf, sizeof (blkbuf), "%u", minor);

        if (ddi_create_minor_node(zfs_dip, blkbuf, S_IFBLK,
            minor, DDI_PSEUDO, 0) == DDI_FAILURE) {
                ddi_remove_minor_node(zfs_dip, chrbuf);
                ddi_soft_state_free(zfsdev_state, minor);
                dmu_objset_disown(os, 1, FTAG);
                mutex_exit(&zfsdev_state_lock);
                return (SET_ERROR(EAGAIN));
        }

        zs = ddi_get_soft_state(zfsdev_state, minor);
        zs->zss_type = ZSST_ZVOL;
        zv = zs->zss_data = kmem_zalloc(sizeof (zvol_state_t), KM_SLEEP);
        (void) strlcpy(zv->zv_name, name, MAXPATHLEN);
        zv->zv_min_bs = DEV_BSHIFT;
        zv->zv_minor = minor;
        zv->zv_objset = os;
        if (dmu_objset_is_snapshot(os) || !spa_writeable(dmu_objset_spa(os)))
                zv->zv_flags |= ZVOL_RDONLY;
        rangelock_init(&zv->zv_rangelock, NULL, NULL);
        list_create(&zv->zv_extents, sizeof (zvol_extent_t),
            offsetof(zvol_extent_t, ze_node));
        /* get and cache the blocksize */
        error = dmu_object_info(os, ZVOL_OBJ, &doi);
        ASSERT(error == 0);
        zv->zv_volblocksize = doi.doi_data_block_size;

        if (spa_writeable(dmu_objset_spa(os))) {
                if (zil_replay_disable)
                        zil_destroy(dmu_objset_zil(os), B_FALSE);
                else
                        zil_replay(os, zv, zvol_replay_vector);
        }
        dmu_objset_disown(os, 1, FTAG);
        zv->zv_objset = NULL;

        zvol_minors++;

        mutex_exit(&zfsdev_state_lock);

        return (0);
}

/*
 * Remove minor node for the specified volume.
 */
static int
zvol_remove_zv(zvol_state_t *zv)
{
        char nmbuf[20];
        minor_t minor = zv->zv_minor;

        ASSERT(MUTEX_HELD(&zfsdev_state_lock));
        if (zv->zv_total_opens != 0)
                return (SET_ERROR(EBUSY));

        (void) snprintf(nmbuf, sizeof (nmbuf), "%u,raw", minor);
        ddi_remove_minor_node(zfs_dip, nmbuf);

        (void) snprintf(nmbuf, sizeof (nmbuf), "%u", minor);
        ddi_remove_minor_node(zfs_dip, nmbuf);

        rangelock_fini(&zv->zv_rangelock);

        kmem_free(zv, sizeof (zvol_state_t));

        ddi_soft_state_free(zfsdev_state, minor);

        zvol_minors--;
        return (0);
}

int
zvol_remove_minor(const char *name)
{
        zvol_state_t *zv;
        int rc;

        mutex_enter(&zfsdev_state_lock);
        if ((zv = zvol_minor_lookup(name)) == NULL) {
                mutex_exit(&zfsdev_state_lock);
                return (SET_ERROR(ENXIO));
        }
        rc = zvol_remove_zv(zv);
        mutex_exit(&zfsdev_state_lock);
        return (rc);
}

int
zvol_first_open(zvol_state_t *zv, boolean_t rdonly)
{
        objset_t *os;
        uint64_t volsize;
        int error;
        uint64_t readonly;
        boolean_t ro;

        ro = (rdonly || (strchr(zv->zv_name, '@') != NULL));
        error = dmu_objset_own(zv->zv_name, DMU_OST_ZVOL, ro, B_TRUE, zv, &os);
        if (error)
                return (error);

        zv->zv_objset = os;
        error = zap_lookup(os, ZVOL_ZAP_OBJ, "size", 8, 1, &volsize);
        if (error) {
                ASSERT(error == 0);
                dmu_objset_disown(os, 1, zv);
                return (error);
        }

        error = dnode_hold(os, ZVOL_OBJ, zvol_tag, &zv->zv_dn);
        if (error) {
                dmu_objset_disown(os, 1, zv);
                return (error);
        }

        zvol_size_changed(zv, volsize);
        zv->zv_zilog = zil_open(os, zvol_get_data);

        VERIFY(dsl_prop_get_integer(zv->zv_name, "readonly", &readonly,
            NULL) == 0);
        if (readonly || dmu_objset_is_snapshot(os) ||
            !spa_writeable(dmu_objset_spa(os)))
                zv->zv_flags |= ZVOL_RDONLY;
        else
                zv->zv_flags &= ~ZVOL_RDONLY;
        return (error);
}

void
zvol_last_close(zvol_state_t *zv)
{
        zil_close(zv->zv_zilog);
        zv->zv_zilog = NULL;

        dnode_rele(zv->zv_dn, zvol_tag);
        zv->zv_dn = NULL;

        /*
         * Evict cached data
         */
        if (dsl_dataset_is_dirty(dmu_objset_ds(zv->zv_objset)) &&
            !(zv->zv_flags & ZVOL_RDONLY))
                txg_wait_synced(dmu_objset_pool(zv->zv_objset), 0);
        dmu_objset_evict_dbufs(zv->zv_objset);

        dmu_objset_disown(zv->zv_objset, 1, zv);
        zv->zv_objset = NULL;
}

int
zvol_prealloc(zvol_state_t *zv)
{
        objset_t *os = zv->zv_objset;
        dmu_tx_t *tx;
        uint64_t refd, avail, usedobjs, availobjs;
        uint64_t resid = zv->zv_volsize;
        uint64_t off = 0;

        /* Check the space usage before attempting to allocate the space */
        dmu_objset_space(os, &refd, &avail, &usedobjs, &availobjs);
        if (avail < zv->zv_volsize)
                return (SET_ERROR(ENOSPC));

        /* Free old extents if they exist */
        zvol_free_extents(zv);

        while (resid != 0) {
                int error;
                uint64_t bytes = MIN(resid, SPA_OLD_MAXBLOCKSIZE);

                tx = dmu_tx_create(os);
                dmu_tx_hold_write(tx, ZVOL_OBJ, off, bytes);
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        dmu_tx_abort(tx);
                        (void) dmu_free_long_range(os, ZVOL_OBJ, 0, off);
                        return (error);
                }
                dmu_prealloc(os, ZVOL_OBJ, off, bytes, tx);
                dmu_tx_commit(tx);
                off += bytes;
                resid -= bytes;
        }
        txg_wait_synced(dmu_objset_pool(os), 0);

        return (0);
}

static int
zvol_update_volsize(objset_t *os, uint64_t volsize)
{
        dmu_tx_t *tx;
        int error;
        uint64_t txg;

        ASSERT(MUTEX_HELD(&zfsdev_state_lock));

        tx = dmu_tx_create(os);
        dmu_tx_hold_zap(tx, ZVOL_ZAP_OBJ, TRUE, NULL);
        dmu_tx_mark_netfree(tx);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                return (error);
        }
        txg = dmu_tx_get_txg(tx);

        error = zap_update(os, ZVOL_ZAP_OBJ, "size", 8, 1,
            &volsize, tx);
        dmu_tx_commit(tx);

        txg_wait_synced(dmu_objset_pool(os), txg);

        if (error == 0)
                error = dmu_free_long_range(os,
                    ZVOL_OBJ, volsize, DMU_OBJECT_END);
        return (error);
}

void
zvol_remove_minors(const char *name)
{
        zvol_state_t *zv;
        char *namebuf;
        minor_t minor;

        namebuf = kmem_zalloc(strlen(name) + 2, KM_SLEEP);
        (void) strncpy(namebuf, name, strlen(name));
        (void) strcat(namebuf, "/");
        mutex_enter(&zfsdev_state_lock);
        for (minor = 1; minor <= ZFSDEV_MAX_MINOR; minor++) {

                zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
                if (zv == NULL)
                        continue;
                if (strncmp(namebuf, zv->zv_name, strlen(namebuf)) == 0)
                        (void) zvol_remove_zv(zv);
        }
        kmem_free(namebuf, strlen(name) + 2);

        mutex_exit(&zfsdev_state_lock);
}

static int
zvol_update_live_volsize(zvol_state_t *zv, uint64_t volsize)
{
        uint64_t old_volsize = 0ULL;
        int error = 0;

        ASSERT(MUTEX_HELD(&zfsdev_state_lock));

        /*
         * Reinitialize the dump area to the new size. If we
         * failed to resize the dump area then restore it back to
         * its original size.  We must set the new volsize prior
         * to calling dumpvp_resize() to ensure that the devices'
         * size(9P) is not visible by the dump subsystem.
         */
        old_volsize = zv->zv_volsize;
        zvol_size_changed(zv, volsize);

        if (zv->zv_flags & ZVOL_DUMPIFIED) {
                if ((error = zvol_dumpify(zv)) != 0 ||
                    (error = dumpvp_resize()) != 0) {
                        int dumpify_error;

                        (void) zvol_update_volsize(zv->zv_objset, old_volsize);
                        zvol_size_changed(zv, old_volsize);
                        dumpify_error = zvol_dumpify(zv);
                        error = dumpify_error ? dumpify_error : error;
                }
        }

        /*
         * Generate a LUN expansion event.
         */
        if (error == 0) {
                char *physpath = kmem_zalloc(MAXPATHLEN, KM_SLEEP);

                (void) snprintf(physpath, MAXPATHLEN, "%s%u", ZVOL_PSEUDO_DEV,
                    zv->zv_minor);

                zfs_post_dle_sysevent(physpath);
                kmem_free(physpath, MAXPATHLEN);
        }
        return (error);
}

int
zvol_set_volsize(const char *name, uint64_t volsize)
{
        zvol_state_t *zv = NULL;
        objset_t *os;
        int error;
        dmu_object_info_t doi;
        uint64_t readonly;
        boolean_t owned = B_FALSE;

        error = dsl_prop_get_integer(name,
            zfs_prop_to_name(ZFS_PROP_READONLY), &readonly, NULL);
        if (error != 0)
                return (error);
        if (readonly)
                return (SET_ERROR(EROFS));

        mutex_enter(&zfsdev_state_lock);
        zv = zvol_minor_lookup(name);

        if (zv == NULL || zv->zv_objset == NULL) {
                if ((error = dmu_objset_own(name, DMU_OST_ZVOL, B_FALSE, B_TRUE,
                    FTAG, &os)) != 0) {
                        mutex_exit(&zfsdev_state_lock);
                        return (error);
                }
                owned = B_TRUE;
                if (zv != NULL)
                        zv->zv_objset = os;
        } else {
                os = zv->zv_objset;
        }

        if ((error = dmu_object_info(os, ZVOL_OBJ, &doi)) != 0 ||
            (error = zvol_check_volsize(volsize, doi.doi_data_block_size)) != 0)
                goto out;

        error = zvol_update_volsize(os, volsize);

        if (error == 0 && zv != NULL)
                error = zvol_update_live_volsize(zv, volsize);
out:
        if (owned) {
                dmu_objset_disown(os, B_TRUE, FTAG);
                if (zv != NULL)
                        zv->zv_objset = NULL;
        }
        mutex_exit(&zfsdev_state_lock);
        return (error);
}

/*ARGSUSED*/
int
zvol_open(dev_t *devp, int flag, int otyp, cred_t *cr)
{
        zvol_state_t *zv;
        int err = 0;

        mutex_enter(&zfsdev_state_lock);

        zv = zfsdev_get_soft_state(getminor(*devp), ZSST_ZVOL);
        if (zv == NULL) {
                mutex_exit(&zfsdev_state_lock);
                return (SET_ERROR(ENXIO));
        }

        if (zv->zv_total_opens == 0)
                err = zvol_first_open(zv, !(flag & FWRITE));
        if (err) {
                mutex_exit(&zfsdev_state_lock);
                return (err);
        }

        if ((flag & FWRITE) && (zv->zv_flags & ZVOL_RDONLY)) {
                err = SET_ERROR(EROFS);
                goto out;
        }
        if (zv->zv_flags & ZVOL_EXCL) {
                err = SET_ERROR(EBUSY);
                goto out;
        }
        if (flag & FEXCL) {
                if (zv->zv_total_opens != 0) {
                        err = SET_ERROR(EBUSY);
                        goto out;
                }
                zv->zv_flags |= ZVOL_EXCL;
        }

        if (zv->zv_open_count[otyp] == 0 || otyp == OTYP_LYR) {
                zv->zv_open_count[otyp]++;
                zv->zv_total_opens++;
        }
        mutex_exit(&zfsdev_state_lock);

        return (err);
out:
        if (zv->zv_total_opens == 0)
                zvol_last_close(zv);
        mutex_exit(&zfsdev_state_lock);
        return (err);
}

/*ARGSUSED*/
int
zvol_close(dev_t dev, int flag, int otyp, cred_t *cr)
{
        minor_t minor = getminor(dev);
        zvol_state_t *zv;
        int error = 0;

        mutex_enter(&zfsdev_state_lock);

        zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
        if (zv == NULL) {
                mutex_exit(&zfsdev_state_lock);
                return (SET_ERROR(ENXIO));
        }

        if (zv->zv_flags & ZVOL_EXCL) {
                ASSERT(zv->zv_total_opens == 1);
                zv->zv_flags &= ~ZVOL_EXCL;
        }

        /*
         * If the open count is zero, this is a spurious close.
         * That indicates a bug in the kernel / DDI framework.
         */
        ASSERT(zv->zv_open_count[otyp] != 0);
        ASSERT(zv->zv_total_opens != 0);

        /*
         * You may get multiple opens, but only one close.
         */
        zv->zv_open_count[otyp]--;
        zv->zv_total_opens--;

        if (zv->zv_total_opens == 0)
                zvol_last_close(zv);

        mutex_exit(&zfsdev_state_lock);
        return (error);
}

/* ARGSUSED */
static void
zvol_get_done(zgd_t *zgd, int error)
{
        if (zgd->zgd_db)
                dmu_buf_rele(zgd->zgd_db, zgd);

        rangelock_exit(zgd->zgd_lr);

        kmem_free(zgd, sizeof (zgd_t));
}

/*
 * Get data to generate a TX_WRITE intent log record.
 */
static int
zvol_get_data(void *arg, lr_write_t *lr, char *buf, struct lwb *lwb, zio_t *zio)
{
        zvol_state_t *zv = arg;
        uint64_t offset = lr->lr_offset;
        uint64_t size = lr->lr_length;  /* length of user data */
        dmu_buf_t *db;
        zgd_t *zgd;
        int error;

        ASSERT3P(lwb, !=, NULL);
        ASSERT3P(zio, !=, NULL);
        ASSERT3U(size, !=, 0);

        zgd = kmem_zalloc(sizeof (zgd_t), KM_SLEEP);
        zgd->zgd_lwb = lwb;

        /*
         * Write records come in two flavors: immediate and indirect.
         * For small writes it's cheaper to store the data with the
         * log record (immediate); for large writes it's cheaper to
         * sync the data and get a pointer to it (indirect) so that
         * we don't have to write the data twice.
         */
        if (buf != NULL) { /* immediate write */
                zgd->zgd_lr = rangelock_enter(&zv->zv_rangelock, offset, size,
                    RL_READER);
                error = dmu_read_by_dnode(zv->zv_dn, offset, size, buf,
                    DMU_READ_NO_PREFETCH);
        } else { /* indirect write */
                /*
                 * Have to lock the whole block to ensure when it's written out
                 * and its checksum is being calculated that no one can change
                 * the data. Contrarily to zfs_get_data we need not re-check
                 * blocksize after we get the lock because it cannot be changed.
                 */
                size = zv->zv_volblocksize;
                offset = P2ALIGN(offset, size);
                zgd->zgd_lr = rangelock_enter(&zv->zv_rangelock, offset, size,
                    RL_READER);
                error = dmu_buf_hold_by_dnode(zv->zv_dn, offset, zgd, &db,
                    DMU_READ_NO_PREFETCH);
                if (error == 0) {
                        blkptr_t *bp = &lr->lr_blkptr;

                        zgd->zgd_db = db;
                        zgd->zgd_bp = bp;

                        ASSERT(db->db_offset == offset);
                        ASSERT(db->db_size == size);

                        error = dmu_sync(zio, lr->lr_common.lrc_txg,
                            zvol_get_done, zgd);

                        if (error == 0)
                                return (0);
                }
        }

        zvol_get_done(zgd, error);

        return (error);
}

/*
 * zvol_log_write() handles synchronous writes using TX_WRITE ZIL transactions.
 *
 * We store data in the log buffers if it's small enough.
 * Otherwise we will later flush the data out via dmu_sync().
 */
ssize_t zvol_immediate_write_sz = 32768;

static void
zvol_log_write(zvol_state_t *zv, dmu_tx_t *tx, offset_t off, ssize_t resid,
    boolean_t commit)
{
        uint32_t blocksize = zv->zv_volblocksize;
        zilog_t *zilog = zv->zv_zilog;
        itx_wr_state_t write_state;

        if (zil_replaying(zilog, tx))
                return;

        if (zilog->zl_logbias == ZFS_LOGBIAS_THROUGHPUT) {
                write_state = WR_INDIRECT;
        } else if (!spa_has_slogs(zilog->zl_spa) &&
            resid >= blocksize && blocksize > zvol_immediate_write_sz) {
                write_state = WR_INDIRECT;
        } else if (commit) {
                write_state = WR_COPIED;
        } else {
                write_state = WR_NEED_COPY;
        }

        while (resid) {
                itx_t *itx;
                lr_write_t *lr;
                itx_wr_state_t wr_state = write_state;
                ssize_t len = resid;

                if (wr_state == WR_COPIED && resid > ZIL_MAX_COPIED_DATA)
                        wr_state = WR_NEED_COPY;
                else if (wr_state == WR_INDIRECT)
                        len = MIN(blocksize - P2PHASE(off, blocksize), resid);

                itx = zil_itx_create(TX_WRITE, sizeof (*lr) +
                    (wr_state == WR_COPIED ? len : 0));
                lr = (lr_write_t *)&itx->itx_lr;
                if (wr_state == WR_COPIED && dmu_read_by_dnode(zv->zv_dn,
                    off, len, lr + 1, DMU_READ_NO_PREFETCH) != 0) {
                        zil_itx_destroy(itx);
                        itx = zil_itx_create(TX_WRITE, sizeof (*lr));
                        lr = (lr_write_t *)&itx->itx_lr;
                        wr_state = WR_NEED_COPY;
                }

                itx->itx_wr_state = wr_state;
                lr->lr_foid = ZVOL_OBJ;
                lr->lr_offset = off;
                lr->lr_length = len;
                lr->lr_blkoff = 0;
                BP_ZERO(&lr->lr_blkptr);

                itx->itx_private = zv;

                zil_itx_assign(zilog, itx, tx);

                off += len;
                resid -= len;
        }
}

static int
zvol_dumpio_vdev(vdev_t *vd, void *addr, uint64_t offset, uint64_t origoffset,
    uint64_t size, boolean_t doread, boolean_t isdump)
{
        if (doread && !vdev_readable(vd))
                return (SET_ERROR(EIO));
        if (!doread && !vdev_writeable(vd))
                return (SET_ERROR(EIO));
        if (vd->vdev_ops->vdev_op_dumpio == NULL)
                return (SET_ERROR(EIO));

        return (vd->vdev_ops->vdev_op_dumpio(vd, addr, size,
            offset, origoffset, doread, isdump));
}

static int
zvol_dumpio(zvol_state_t *zv, void *addr, uint64_t offset, uint64_t size,
    boolean_t doread, boolean_t isdump)
{
        vdev_t *vd;
        int error;
        zvol_extent_t *ze;
        spa_t *spa = dmu_objset_spa(zv->zv_objset);

        /* Must be sector aligned, and not stradle a block boundary. */
        if (P2PHASE(offset, DEV_BSIZE) || P2PHASE(size, DEV_BSIZE) ||
            P2BOUNDARY(offset, size, zv->zv_volblocksize)) {
                return (SET_ERROR(EINVAL));
        }
        VERIFY3U(size, <=, zv->zv_volblocksize);

        /* Locate the extent this belongs to */
        for (ze = list_head(&zv->zv_extents);
            ze != NULL && offset >= ze->ze_nblks * zv->zv_volblocksize;
            ze = list_next(&zv->zv_extents, ze)) {
                offset -= ze->ze_nblks * zv->zv_volblocksize;
        }

        if (ze == NULL)
                return (SET_ERROR(EINVAL));

        if (!ddi_in_panic())
                spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);

        vd = vdev_lookup_top(spa, DVA_GET_VDEV(&ze->ze_dva));
        offset += DVA_GET_OFFSET(&ze->ze_dva);
        error = zvol_dumpio_vdev(vd, addr, offset, DVA_GET_OFFSET(&ze->ze_dva),
            size, doread, isdump);

        if (!ddi_in_panic())
                spa_config_exit(spa, SCL_STATE, FTAG);

        return (error);
}

int
zvol_strategy(buf_t *bp)
{
        zfs_soft_state_t *zs = NULL;
        zvol_state_t *zv;
        uint64_t off, volsize;
        size_t resid;
        char *addr;
        objset_t *os;
        int error = 0;
        boolean_t doread = !!(bp->b_flags & B_READ);
        boolean_t is_dumpified;
        boolean_t commit;

        if (getminor(bp->b_edev) == 0) {
                error = SET_ERROR(EINVAL);
        } else {
                zs = ddi_get_soft_state(zfsdev_state, getminor(bp->b_edev));
                if (zs == NULL)
                        error = SET_ERROR(ENXIO);
                else if (zs->zss_type != ZSST_ZVOL)
                        error = SET_ERROR(EINVAL);
        }

        if (error) {
                bioerror(bp, error);
                biodone(bp);
                return (0);
        }

        zv = zs->zss_data;

        if (!(bp->b_flags & B_READ) && (zv->zv_flags & ZVOL_RDONLY)) {
                bioerror(bp, EROFS);
                biodone(bp);
                return (0);
        }

        off = ldbtob(bp->b_blkno);
        volsize = zv->zv_volsize;

        os = zv->zv_objset;
        ASSERT(os != NULL);

        bp_mapin(bp);
        addr = bp->b_un.b_addr;
        resid = bp->b_bcount;

        if (resid > 0 && off >= volsize) {
                bioerror(bp, EIO);
                biodone(bp);
                return (0);
        }

        is_dumpified = zv->zv_flags & ZVOL_DUMPIFIED;
        commit = ((!(bp->b_flags & B_ASYNC) &&
            !(zv->zv_flags & ZVOL_WCE)) ||
            zv->zv_objset->os_sync == ZFS_SYNC_ALWAYS) &&
            !doread && !is_dumpified;

        smt_begin_unsafe();

        /*
         * There must be no buffer changes when doing a dmu_sync() because
         * we can't change the data whilst calculating the checksum.
         */
        locked_range_t *lr = rangelock_enter(&zv->zv_rangelock, off, resid,
            doread ? RL_READER : RL_WRITER);

        while (resid != 0 && off < volsize) {
                size_t size = MIN(resid, zvol_maxphys);
                if (is_dumpified) {
                        size = MIN(size, P2END(off, zv->zv_volblocksize) - off);
                        error = zvol_dumpio(zv, addr, off, size,
                            doread, B_FALSE);
                } else if (doread) {
                        error = dmu_read(os, ZVOL_OBJ, off, size, addr,
                            DMU_READ_PREFETCH);
                } else {
                        dmu_tx_t *tx = dmu_tx_create(os);
                        dmu_tx_hold_write(tx, ZVOL_OBJ, off, size);
                        error = dmu_tx_assign(tx, TXG_WAIT);
                        if (error) {
                                dmu_tx_abort(tx);
                        } else {
                                dmu_write(os, ZVOL_OBJ, off, size, addr, tx);
                                zvol_log_write(zv, tx, off, size, commit);
                                dmu_tx_commit(tx);
                        }
                }
                if (error) {
                        /* convert checksum errors into IO errors */
                        if (error == ECKSUM)
                                error = SET_ERROR(EIO);
                        break;
                }
                off += size;
                addr += size;
                resid -= size;
        }
        rangelock_exit(lr);

        if ((bp->b_resid = resid) == bp->b_bcount)
                bioerror(bp, off > volsize ? EINVAL : error);

        if (commit)
                zil_commit(zv->zv_zilog, ZVOL_OBJ);
        biodone(bp);

        smt_end_unsafe();

        return (0);
}

/*
 * Set the buffer count to the zvol maximum transfer.
 * Using our own routine instead of the default minphys()
 * means that for larger writes we write bigger buffers on X86
 * (128K instead of 56K) and flush the disk write cache less often
 * (every zvol_maxphys - currently 1MB) instead of minphys (currently
 * 56K on X86 and 128K on sparc).
 */
void
zvol_minphys(struct buf *bp)
{
        if (bp->b_bcount > zvol_maxphys)
                bp->b_bcount = zvol_maxphys;
}

int
zvol_dump(dev_t dev, caddr_t addr, daddr_t blkno, int nblocks)
{
        minor_t minor = getminor(dev);
        zvol_state_t *zv;
        int error = 0;
        uint64_t size;
        uint64_t boff;
        uint64_t resid;

        zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
        if (zv == NULL)
                return (SET_ERROR(ENXIO));

        if ((zv->zv_flags & ZVOL_DUMPIFIED) == 0)
                return (SET_ERROR(EINVAL));

        boff = ldbtob(blkno);
        resid = ldbtob(nblocks);

        VERIFY3U(boff + resid, <=, zv->zv_volsize);

        while (resid) {
                size = MIN(resid, P2END(boff, zv->zv_volblocksize) - boff);
                error = zvol_dumpio(zv, addr, boff, size, B_FALSE, B_TRUE);
                if (error)
                        break;
                boff += size;
                addr += size;
                resid -= size;
        }

        return (error);
}

/*ARGSUSED*/
int
zvol_read(dev_t dev, uio_t *uio, cred_t *cr)
{
        minor_t minor = getminor(dev);
        zvol_state_t *zv;
        uint64_t volsize;
        int error = 0;

        zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
        if (zv == NULL)
                return (SET_ERROR(ENXIO));

        volsize = zv->zv_volsize;
        if (uio->uio_resid > 0 &&
            (uio->uio_loffset < 0 || uio->uio_loffset >= volsize))
                return (SET_ERROR(EIO));

        if (zv->zv_flags & ZVOL_DUMPIFIED) {
                error = physio(zvol_strategy, NULL, dev, B_READ,
                    zvol_minphys, uio);
                return (error);
        }

        smt_begin_unsafe();

        locked_range_t *lr = rangelock_enter(&zv->zv_rangelock,
            uio->uio_loffset, uio->uio_resid, RL_READER);
        while (uio->uio_resid > 0 && uio->uio_loffset < volsize) {
                uint64_t bytes = MIN(uio->uio_resid, DMU_MAX_ACCESS >> 1);

                /* don't read past the end */
                if (bytes > volsize - uio->uio_loffset)
                        bytes = volsize - uio->uio_loffset;

                error =  dmu_read_uio(zv->zv_objset, ZVOL_OBJ, uio, bytes);
                if (error) {
                        /* convert checksum errors into IO errors */
                        if (error == ECKSUM)
                                error = SET_ERROR(EIO);
                        break;
                }
        }
        rangelock_exit(lr);

        smt_end_unsafe();

        return (error);
}

/*ARGSUSED*/
int
zvol_write(dev_t dev, uio_t *uio, cred_t *cr)
{
        minor_t minor = getminor(dev);
        zvol_state_t *zv;
        uint64_t volsize;
        int error = 0;
        boolean_t commit;

        zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
        if (zv == NULL)
                return (SET_ERROR(ENXIO));

        volsize = zv->zv_volsize;
        if (uio->uio_resid > 0 &&
            (uio->uio_loffset < 0 || uio->uio_loffset >= volsize))
                return (SET_ERROR(EIO));

        if (zv->zv_flags & ZVOL_DUMPIFIED) {
                error = physio(zvol_strategy, NULL, dev, B_WRITE,
                    zvol_minphys, uio);
                return (error);
        }

        smt_begin_unsafe();

        commit = !(zv->zv_flags & ZVOL_WCE) ||
            zv->zv_objset->os_sync == ZFS_SYNC_ALWAYS;

        locked_range_t *lr = rangelock_enter(&zv->zv_rangelock,
            uio->uio_loffset, uio->uio_resid, RL_WRITER);
        while (uio->uio_resid > 0 && uio->uio_loffset < volsize) {
                uint64_t bytes = MIN(uio->uio_resid, DMU_MAX_ACCESS >> 1);
                uint64_t off = uio->uio_loffset;
                dmu_tx_t *tx = dmu_tx_create(zv->zv_objset);

                if (bytes > volsize - off)      /* don't write past the end */
                        bytes = volsize - off;

                dmu_tx_hold_write_by_dnode(tx, zv->zv_dn, off, bytes);
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        dmu_tx_abort(tx);
                        break;
                }
                error = dmu_write_uio_dnode(zv->zv_dn, uio, bytes, tx);
                if (error == 0)
                        zvol_log_write(zv, tx, off, bytes, commit);
                dmu_tx_commit(tx);

                if (error)
                        break;
        }
        rangelock_exit(lr);

        if (commit)
                zil_commit(zv->zv_zilog, ZVOL_OBJ);

        smt_end_unsafe();

        return (error);
}

int
zvol_getefi(void *arg, int flag, uint64_t vs, uint8_t bs)
{
        struct uuid uuid = EFI_RESERVED;
        efi_gpe_t gpe = { 0 };
        uint32_t crc;
        dk_efi_t efi;
        int length;
        char *ptr;

        if (ddi_copyin(arg, &efi, sizeof (dk_efi_t), flag))
                return (SET_ERROR(EFAULT));
        ptr = (char *)(uintptr_t)efi.dki_data_64;
        length = efi.dki_length;
        /*
         * Some clients may attempt to request a PMBR for the
         * zvol.  Currently this interface will return EINVAL to
         * such requests.  These requests could be supported by
         * adding a check for lba == 0 and consing up an appropriate
         * PMBR.
         */
        if (efi.dki_lba < 1 || efi.dki_lba > 2 || length <= 0)
                return (SET_ERROR(EINVAL));

        gpe.efi_gpe_StartingLBA = LE_64(34ULL);
        gpe.efi_gpe_EndingLBA = LE_64((vs >> bs) - 1);
        UUID_LE_CONVERT(gpe.efi_gpe_PartitionTypeGUID, uuid);

        if (efi.dki_lba == 1) {
                efi_gpt_t gpt = { 0 };

                gpt.efi_gpt_Signature = LE_64(EFI_SIGNATURE);
                gpt.efi_gpt_Revision = LE_32(EFI_VERSION_CURRENT);
                gpt.efi_gpt_HeaderSize = LE_32(EFI_HEADER_SIZE);
                gpt.efi_gpt_MyLBA = LE_64(1ULL);
                gpt.efi_gpt_FirstUsableLBA = LE_64(34ULL);
                gpt.efi_gpt_LastUsableLBA = LE_64((vs >> bs) - 1);
                gpt.efi_gpt_PartitionEntryLBA = LE_64(2ULL);
                gpt.efi_gpt_NumberOfPartitionEntries = LE_32(1);
                gpt.efi_gpt_SizeOfPartitionEntry =
                    LE_32(sizeof (efi_gpe_t));
                CRC32(crc, &gpe, sizeof (gpe), -1U, crc32_table);
                gpt.efi_gpt_PartitionEntryArrayCRC32 = LE_32(~crc);
                CRC32(crc, &gpt, EFI_HEADER_SIZE, -1U, crc32_table);
                gpt.efi_gpt_HeaderCRC32 = LE_32(~crc);
                if (ddi_copyout(&gpt, ptr, MIN(sizeof (gpt), length),
                    flag))
                        return (SET_ERROR(EFAULT));
                ptr += sizeof (gpt);
                length -= sizeof (gpt);
        }
        if (length > 0 && ddi_copyout(&gpe, ptr, MIN(sizeof (gpe),
            length), flag))
                return (SET_ERROR(EFAULT));
        return (0);
}

/*
 * BEGIN entry points to allow external callers access to the volume.
 */
/*
 * Return the volume parameters needed for access from an external caller.
 * These values are invariant as long as the volume is held open.
 */
int
zvol_get_volume_params(minor_t minor, uint64_t *blksize,
    uint64_t *max_xfer_len, void **minor_hdl, void **objset_hdl, void **zil_hdl,
    void **rl_hdl, void **dnode_hdl)
{
        zvol_state_t *zv;

        zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
        if (zv == NULL)
                return (SET_ERROR(ENXIO));
        if (zv->zv_flags & ZVOL_DUMPIFIED)
                return (SET_ERROR(ENXIO));

        ASSERT(blksize && max_xfer_len && minor_hdl &&
            objset_hdl && zil_hdl && rl_hdl && dnode_hdl);

        *blksize = zv->zv_volblocksize;
        *max_xfer_len = (uint64_t)zvol_maxphys;
        *minor_hdl = zv;
        *objset_hdl = zv->zv_objset;
        *zil_hdl = zv->zv_zilog;
        *rl_hdl = &zv->zv_rangelock;
        *dnode_hdl = zv->zv_dn;
        return (0);
}

/*
 * Return the current volume size to an external caller.
 * The size can change while the volume is open.
 */
uint64_t
zvol_get_volume_size(void *minor_hdl)
{
        zvol_state_t *zv = minor_hdl;

        return (zv->zv_volsize);
}

/*
 * Return the current WCE setting to an external caller.
 * The WCE setting can change while the volume is open.
 */
int
zvol_get_volume_wce(void *minor_hdl)
{
        zvol_state_t *zv = minor_hdl;

        return ((zv->zv_flags & ZVOL_WCE) ? 1 : 0);
}

/*
 * Entry point for external callers to zvol_log_write
 */
void
zvol_log_write_minor(void *minor_hdl, dmu_tx_t *tx, offset_t off, ssize_t resid,
    boolean_t commit)
{
        zvol_state_t *zv = minor_hdl;

        zvol_log_write(zv, tx, off, resid, commit);
}
/*
 * END entry points to allow external callers access to the volume.
 */

/*
 * Log a DKIOCFREE/free-long-range to the ZIL with TX_TRUNCATE.
 */
static void
zvol_log_truncate(zvol_state_t *zv, dmu_tx_t *tx, uint64_t off, uint64_t len)
{
        itx_t *itx;
        lr_truncate_t *lr;
        zilog_t *zilog = zv->zv_zilog;

        if (zil_replaying(zilog, tx))
                return;

        itx = zil_itx_create(TX_TRUNCATE, sizeof (*lr));
        lr = (lr_truncate_t *)&itx->itx_lr;
        lr->lr_foid = ZVOL_OBJ;
        lr->lr_offset = off;
        lr->lr_length = len;

        zil_itx_assign(zilog, itx, tx);
}

/*
 * Dirtbag ioctls to support mkfs(8) for UFS filesystems.  See dkio(4I).
 * Also a dirtbag dkio ioctl for unmap/free-block functionality.
 */
/*ARGSUSED*/
int
zvol_ioctl(dev_t dev, int cmd, intptr_t arg, int flag, cred_t *cr, int *rvalp)
{
        zvol_state_t *zv;
        struct dk_callback *dkc;
        int i, error = 0;
        locked_range_t *lr;

        mutex_enter(&zfsdev_state_lock);

        zv = zfsdev_get_soft_state(getminor(dev), ZSST_ZVOL);

        if (zv == NULL) {
                mutex_exit(&zfsdev_state_lock);
                return (SET_ERROR(ENXIO));
        }
        ASSERT(zv->zv_total_opens > 0);

        switch (cmd) {

        case DKIOCINFO:
        {
                struct dk_cinfo dki;

                bzero(&dki, sizeof (dki));
                (void) strcpy(dki.dki_cname, "zvol");
                (void) strcpy(dki.dki_dname, "zvol");
                dki.dki_ctype = DKC_UNKNOWN;
                dki.dki_unit = getminor(dev);
                dki.dki_maxtransfer =
                    1 << (SPA_OLD_MAXBLOCKSHIFT - zv->zv_min_bs);
                mutex_exit(&zfsdev_state_lock);
                if (ddi_copyout(&dki, (void *)arg, sizeof (dki), flag))
                        error = SET_ERROR(EFAULT);
                return (error);
        }

        case DKIOCGMEDIAINFO:
        {
                struct dk_minfo dkm;

                bzero(&dkm, sizeof (dkm));
                dkm.dki_lbsize = 1U << zv->zv_min_bs;
                dkm.dki_capacity = zv->zv_volsize >> zv->zv_min_bs;
                dkm.dki_media_type = DK_UNKNOWN;
                mutex_exit(&zfsdev_state_lock);
                if (ddi_copyout(&dkm, (void *)arg, sizeof (dkm), flag))
                        error = SET_ERROR(EFAULT);
                return (error);
        }

        case DKIOCGMEDIAINFOEXT:
        {
                struct dk_minfo_ext dkmext;
                size_t len;

                bzero(&dkmext, sizeof (dkmext));
                dkmext.dki_lbsize = 1U << zv->zv_min_bs;
                dkmext.dki_pbsize = zv->zv_volblocksize;
                dkmext.dki_capacity = zv->zv_volsize >> zv->zv_min_bs;
                dkmext.dki_media_type = DK_UNKNOWN;
                mutex_exit(&zfsdev_state_lock);

                switch (ddi_model_convert_from(flag & FMODELS)) {
                case DDI_MODEL_ILP32:
                        len = sizeof (struct dk_minfo_ext32);
                        break;
                default:
                        len = sizeof (struct dk_minfo_ext);
                        break;
                }

                if (ddi_copyout(&dkmext, (void *)arg, len, flag))
                        error = SET_ERROR(EFAULT);
                return (error);
        }

        case DKIOCGETEFI:
        {
                uint64_t vs = zv->zv_volsize;
                uint8_t bs = zv->zv_min_bs;

                mutex_exit(&zfsdev_state_lock);
                error = zvol_getefi((void *)arg, flag, vs, bs);
                return (error);
        }

        case DKIOCFLUSHWRITECACHE:
                dkc = (struct dk_callback *)arg;
                mutex_exit(&zfsdev_state_lock);

                smt_begin_unsafe();

                zil_commit(zv->zv_zilog, ZVOL_OBJ);
                if ((flag & FKIOCTL) && dkc != NULL && dkc->dkc_callback) {
                        (*dkc->dkc_callback)(dkc->dkc_cookie, error);
                        error = 0;
                }

                smt_end_unsafe();

                return (error);

        case DKIOCGETWCE:
        {
                int wce = (zv->zv_flags & ZVOL_WCE) ? 1 : 0;
                if (ddi_copyout(&wce, (void *)arg, sizeof (int),
                    flag))
                        error = SET_ERROR(EFAULT);
                break;
        }
        case DKIOCSETWCE:
        {
                int wce;
                if (ddi_copyin((void *)arg, &wce, sizeof (int),
                    flag)) {
                        error = SET_ERROR(EFAULT);
                        break;
                }
                if (wce) {
                        zv->zv_flags |= ZVOL_WCE;
                        mutex_exit(&zfsdev_state_lock);
                } else {
                        zv->zv_flags &= ~ZVOL_WCE;
                        mutex_exit(&zfsdev_state_lock);
                        smt_begin_unsafe();
                        zil_commit(zv->zv_zilog, ZVOL_OBJ);
                        smt_end_unsafe();
                }
                return (0);
        }

        case DKIOCGGEOM:
        case DKIOCGVTOC:
                /*
                 * commands using these (like prtvtoc) expect ENOTSUP
                 * since we're emulating an EFI label
                 */
                error = SET_ERROR(ENOTSUP);
                break;

        case DKIOCDUMPINIT:
                lr = rangelock_enter(&zv->zv_rangelock, 0, zv->zv_volsize,
                    RL_WRITER);
                error = zvol_dumpify(zv);
                rangelock_exit(lr);
                break;

        case DKIOCDUMPFINI:
                if (!(zv->zv_flags & ZVOL_DUMPIFIED))
                        break;
                lr = rangelock_enter(&zv->zv_rangelock, 0, zv->zv_volsize,
                    RL_WRITER);
                error = zvol_dump_fini(zv);
                rangelock_exit(lr);
                break;

        case DKIOCFREE:
        {
                dkioc_free_list_t *dfl;
                dmu_tx_t *tx;

                if (!zvol_unmap_enabled)
                        break;

                if (!(flag & FKIOCTL)) {
                        error = dfl_copyin((void *)arg, &dfl, flag, KM_SLEEP);
                        if (error != 0)
                                break;
                } else {
                        dfl = (dkioc_free_list_t *)arg;
                        ASSERT3U(dfl->dfl_num_exts, <=, DFL_COPYIN_MAX_EXTS);
                        if (dfl->dfl_num_exts > DFL_COPYIN_MAX_EXTS) {
                                error = SET_ERROR(EINVAL);
                                break;
                        }
                }

                mutex_exit(&zfsdev_state_lock);

                smt_begin_unsafe();

                for (int i = 0; i < dfl->dfl_num_exts; i++) {
                        uint64_t start = dfl->dfl_exts[i].dfle_start,
                            length = dfl->dfl_exts[i].dfle_length,
                            end = start + length;

                        /*
                         * Apply Postel's Law to length-checking.  If they
                         * overshoot, just blank out until the end, if there's
                         * a need to blank out anything.
                         */
                        if (start >= zv->zv_volsize)
                                continue;       /* No need to do anything... */
                        if (end > zv->zv_volsize) {
                                end = DMU_OBJECT_END;
                                length = end - start;
                        }

                        lr = rangelock_enter(&zv->zv_rangelock, start, length,
                            RL_WRITER);
                        tx = dmu_tx_create(zv->zv_objset);
                        error = dmu_tx_assign(tx, TXG_WAIT);
                        if (error != 0) {
                                dmu_tx_abort(tx);
                        } else {
                                zvol_log_truncate(zv, tx, start, length);
                                dmu_tx_commit(tx);
                                error = dmu_free_long_range(zv->zv_objset,
                                    ZVOL_OBJ, start, length);
                        }

                        rangelock_exit(lr);

                        if (error != 0)
                                break;
                }

                /*
                 * If the write-cache is disabled, 'sync' property
                 * is set to 'always', or if the caller is asking for
                 * a synchronous free, commit this operation to the zil.
                 * This will sync any previous uncommitted writes to the
                 * zvol object.
                 * Can be overridden by the zvol_unmap_sync_enabled tunable.
                 */
                if ((error == 0) && zvol_unmap_sync_enabled &&
                    (!(zv->zv_flags & ZVOL_WCE) ||
                    (zv->zv_objset->os_sync == ZFS_SYNC_ALWAYS) ||
                    (dfl->dfl_flags & DF_WAIT_SYNC))) {
                        zil_commit(zv->zv_zilog, ZVOL_OBJ);
                }

                if (!(flag & FKIOCTL))
                        dfl_free(dfl);

                smt_end_unsafe();

                return (error);
        }

        case DKIOC_CANFREE:
                i = zvol_unmap_enabled ? 1 : 0;
                if (ddi_copyout(&i, (void *)arg, sizeof (int), flag) != 0) {
                        error = EFAULT;
                } else {
                        error = 0;
                }
                break;

        default:
                error = SET_ERROR(ENOTTY);
                break;

        }
        mutex_exit(&zfsdev_state_lock);
        return (error);
}

int
zvol_busy(void)
{
        return (zvol_minors != 0);
}

void
zvol_init(void)
{
        VERIFY(ddi_soft_state_init(&zfsdev_state, sizeof (zfs_soft_state_t),
            1) == 0);
        mutex_init(&zfsdev_state_lock, NULL, MUTEX_DEFAULT, NULL);
}

void
zvol_fini(void)
{
        mutex_destroy(&zfsdev_state_lock);
        ddi_soft_state_fini(&zfsdev_state);
}

/*ARGSUSED*/
static int
zfs_mvdev_dump_feature_check(void *arg, dmu_tx_t *tx)
{
        spa_t *spa = dmu_tx_pool(tx)->dp_spa;

        if (spa_feature_is_active(spa, SPA_FEATURE_MULTI_VDEV_CRASH_DUMP))
                return (1);
        return (0);
}

/*ARGSUSED*/
static void
zfs_mvdev_dump_activate_feature_sync(void *arg, dmu_tx_t *tx)
{
        spa_t *spa = dmu_tx_pool(tx)->dp_spa;

        spa_feature_incr(spa, SPA_FEATURE_MULTI_VDEV_CRASH_DUMP, tx);
}

static int
zvol_dump_init(zvol_state_t *zv, boolean_t resize)
{
        dmu_tx_t *tx;
        int error;
        objset_t *os = zv->zv_objset;
        spa_t *spa = dmu_objset_spa(os);
        vdev_t *vd = spa->spa_root_vdev;
        nvlist_t *nv = NULL;
        uint64_t version = spa_version(spa);
        uint64_t checksum, compress, refresrv, vbs, dedup;

        ASSERT(MUTEX_HELD(&zfsdev_state_lock));
        ASSERT(vd->vdev_ops == &vdev_root_ops);

        error = dmu_free_long_range(zv->zv_objset, ZVOL_OBJ, 0,
            DMU_OBJECT_END);
        if (error != 0)
                return (error);
        /* wait for dmu_free_long_range to actually free the blocks */
        txg_wait_synced(dmu_objset_pool(zv->zv_objset), 0);

        /*
         * If the pool on which the dump device is being initialized has more
         * than one child vdev, check that the MULTI_VDEV_CRASH_DUMP feature is
         * enabled.  If so, bump that feature's counter to indicate that the
         * feature is active. We also check the vdev type to handle the
         * following case:
         *   # zpool create test raidz disk1 disk2 disk3
         *   Now have spa_root_vdev->vdev_children == 1 (the raidz vdev),
         *   the raidz vdev itself has 3 children.
         */
        if (vd->vdev_children > 1 || vd->vdev_ops == &vdev_raidz_ops) {
                if (!spa_feature_is_enabled(spa,
                    SPA_FEATURE_MULTI_VDEV_CRASH_DUMP))
                        return (SET_ERROR(ENOTSUP));
                (void) dsl_sync_task(spa_name(spa),
                    zfs_mvdev_dump_feature_check,
                    zfs_mvdev_dump_activate_feature_sync, NULL,
                    2, ZFS_SPACE_CHECK_RESERVED);
        }

        if (!resize) {
                error = dsl_prop_get_integer(zv->zv_name,
                    zfs_prop_to_name(ZFS_PROP_COMPRESSION), &compress, NULL);
                if (error == 0) {
                        error = dsl_prop_get_integer(zv->zv_name,
                            zfs_prop_to_name(ZFS_PROP_CHECKSUM), &checksum,
                            NULL);
                }
                if (error == 0) {
                        error = dsl_prop_get_integer(zv->zv_name,
                            zfs_prop_to_name(ZFS_PROP_REFRESERVATION),
                            &refresrv, NULL);
                }
                if (error == 0) {
                        error = dsl_prop_get_integer(zv->zv_name,
                            zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), &vbs,
                            NULL);
                }
                if (version >= SPA_VERSION_DEDUP && error == 0) {
                        error = dsl_prop_get_integer(zv->zv_name,
                            zfs_prop_to_name(ZFS_PROP_DEDUP), &dedup, NULL);
                }
        }
        if (error != 0)
                return (error);

        tx = dmu_tx_create(os);
        dmu_tx_hold_zap(tx, ZVOL_ZAP_OBJ, TRUE, NULL);
        dmu_tx_hold_bonus(tx, ZVOL_OBJ);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error != 0) {
                dmu_tx_abort(tx);
                return (error);
        }

        /*
         * If we are resizing the dump device then we only need to
         * update the refreservation to match the newly updated
         * zvolsize. Otherwise, we save off the original state of the
         * zvol so that we can restore them if the zvol is ever undumpified.
         */
        if (resize) {
                error = zap_update(os, ZVOL_ZAP_OBJ,
                    zfs_prop_to_name(ZFS_PROP_REFRESERVATION), 8, 1,
                    &zv->zv_volsize, tx);
        } else {
                error = zap_update(os, ZVOL_ZAP_OBJ,
                    zfs_prop_to_name(ZFS_PROP_COMPRESSION), 8, 1,
                    &compress, tx);
                if (error == 0) {
                        error = zap_update(os, ZVOL_ZAP_OBJ,
                            zfs_prop_to_name(ZFS_PROP_CHECKSUM), 8, 1,
                            &checksum, tx);
                }
                if (error == 0) {
                        error = zap_update(os, ZVOL_ZAP_OBJ,
                            zfs_prop_to_name(ZFS_PROP_REFRESERVATION), 8, 1,
                            &refresrv, tx);
                }
                if (error == 0) {
                        error = zap_update(os, ZVOL_ZAP_OBJ,
                            zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), 8, 1,
                            &vbs, tx);
                }
                if (error == 0) {
                        error = dmu_object_set_blocksize(
                            os, ZVOL_OBJ, SPA_OLD_MAXBLOCKSIZE, 0, tx);
                }
                if (version >= SPA_VERSION_DEDUP && error == 0) {
                        error = zap_update(os, ZVOL_ZAP_OBJ,
                            zfs_prop_to_name(ZFS_PROP_DEDUP), 8, 1,
                            &dedup, tx);
                }
                if (error == 0)
                        zv->zv_volblocksize = SPA_OLD_MAXBLOCKSIZE;
        }
        dmu_tx_commit(tx);

        /*
         * We only need update the zvol's property if we are initializing
         * the dump area for the first time.
         */
        if (error == 0 && !resize) {
                /*
                 * If MULTI_VDEV_CRASH_DUMP is active, use the NOPARITY checksum
                 * function.  Otherwise, use the old default -- OFF.
                 */
                checksum = spa_feature_is_active(spa,
                    SPA_FEATURE_MULTI_VDEV_CRASH_DUMP) ? ZIO_CHECKSUM_NOPARITY :
                    ZIO_CHECKSUM_OFF;

                VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_SLEEP) == 0);
                VERIFY(nvlist_add_uint64(nv,
                    zfs_prop_to_name(ZFS_PROP_REFRESERVATION), 0) == 0);
                VERIFY(nvlist_add_uint64(nv,
                    zfs_prop_to_name(ZFS_PROP_COMPRESSION),
                    ZIO_COMPRESS_OFF) == 0);
                VERIFY(nvlist_add_uint64(nv,
                    zfs_prop_to_name(ZFS_PROP_CHECKSUM),
                    checksum) == 0);
                if (version >= SPA_VERSION_DEDUP) {
                        VERIFY(nvlist_add_uint64(nv,
                            zfs_prop_to_name(ZFS_PROP_DEDUP),
                            ZIO_CHECKSUM_OFF) == 0);
                }

                error = zfs_set_prop_nvlist(zv->zv_name, ZPROP_SRC_LOCAL,
                    nv, NULL);
                nvlist_free(nv);
        }

        /* Allocate the space for the dump */
        if (error == 0)
                error = zvol_prealloc(zv);
        return (error);
}

static int
zvol_dumpify(zvol_state_t *zv)
{
        int error = 0;
        uint64_t dumpsize = 0;
        dmu_tx_t *tx;
        objset_t *os = zv->zv_objset;

        if (zv->zv_flags & ZVOL_RDONLY)
                return (SET_ERROR(EROFS));

        if (os->os_encrypted)
                return (SET_ERROR(ENOTSUP));

        if (zap_lookup(zv->zv_objset, ZVOL_ZAP_OBJ, ZVOL_DUMPSIZE,
            8, 1, &dumpsize) != 0 || dumpsize != zv->zv_volsize) {
                boolean_t resize = (dumpsize > 0);

                if ((error = zvol_dump_init(zv, resize)) != 0) {
                        (void) zvol_dump_fini(zv);
                        return (error);
                }
        }

        /*
         * Build up our lba mapping.
         */
        error = zvol_get_lbas(zv);
        if (error) {
                (void) zvol_dump_fini(zv);
                return (error);
        }

        tx = dmu_tx_create(os);
        dmu_tx_hold_zap(tx, ZVOL_ZAP_OBJ, TRUE, NULL);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                (void) zvol_dump_fini(zv);
                return (error);
        }

        zv->zv_flags |= ZVOL_DUMPIFIED;
        error = zap_update(os, ZVOL_ZAP_OBJ, ZVOL_DUMPSIZE, 8, 1,
            &zv->zv_volsize, tx);
        dmu_tx_commit(tx);

        if (error) {
                (void) zvol_dump_fini(zv);
                return (error);
        }

        txg_wait_synced(dmu_objset_pool(os), 0);
        return (0);
}

static int
zvol_dump_fini(zvol_state_t *zv)
{
        dmu_tx_t *tx;
        objset_t *os = zv->zv_objset;
        nvlist_t *nv;
        int error = 0;
        uint64_t checksum, compress, refresrv, vbs, dedup;
        uint64_t version = spa_version(dmu_objset_spa(zv->zv_objset));

        /*
         * Attempt to restore the zvol back to its pre-dumpified state.
         * This is a best-effort attempt as it's possible that not all
         * of these properties were initialized during the dumpify process
         * (i.e. error during zvol_dump_init).
         */

        tx = dmu_tx_create(os);
        dmu_tx_hold_zap(tx, ZVOL_ZAP_OBJ, TRUE, NULL);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                return (error);
        }
        (void) zap_remove(os, ZVOL_ZAP_OBJ, ZVOL_DUMPSIZE, tx);
        dmu_tx_commit(tx);

        (void) zap_lookup(zv->zv_objset, ZVOL_ZAP_OBJ,
            zfs_prop_to_name(ZFS_PROP_CHECKSUM), 8, 1, &checksum);
        (void) zap_lookup(zv->zv_objset, ZVOL_ZAP_OBJ,
            zfs_prop_to_name(ZFS_PROP_COMPRESSION), 8, 1, &compress);
        (void) zap_lookup(zv->zv_objset, ZVOL_ZAP_OBJ,
            zfs_prop_to_name(ZFS_PROP_REFRESERVATION), 8, 1, &refresrv);
        (void) zap_lookup(zv->zv_objset, ZVOL_ZAP_OBJ,
            zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), 8, 1, &vbs);

        VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_SLEEP) == 0);
        (void) nvlist_add_uint64(nv,
            zfs_prop_to_name(ZFS_PROP_CHECKSUM), checksum);
        (void) nvlist_add_uint64(nv,
            zfs_prop_to_name(ZFS_PROP_COMPRESSION), compress);
        (void) nvlist_add_uint64(nv,
            zfs_prop_to_name(ZFS_PROP_REFRESERVATION), refresrv);
        if (version >= SPA_VERSION_DEDUP &&
            zap_lookup(zv->zv_objset, ZVOL_ZAP_OBJ,
            zfs_prop_to_name(ZFS_PROP_DEDUP), 8, 1, &dedup) == 0) {
                (void) nvlist_add_uint64(nv,
                    zfs_prop_to_name(ZFS_PROP_DEDUP), dedup);
        }
        (void) zfs_set_prop_nvlist(zv->zv_name, ZPROP_SRC_LOCAL,
            nv, NULL);
        nvlist_free(nv);

        zvol_free_extents(zv);
        zv->zv_flags &= ~ZVOL_DUMPIFIED;
        (void) dmu_free_long_range(os, ZVOL_OBJ, 0, DMU_OBJECT_END);
        /* wait for dmu_free_long_range to actually free the blocks */
        txg_wait_synced(dmu_objset_pool(zv->zv_objset), 0);
        tx = dmu_tx_create(os);
        dmu_tx_hold_bonus(tx, ZVOL_OBJ);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                return (error);
        }
        if (dmu_object_set_blocksize(os, ZVOL_OBJ, vbs, 0, tx) == 0)
                zv->zv_volblocksize = vbs;
        dmu_tx_commit(tx);

        return (0);
}