Move the world out of /zfs/ and seperate out module build tree

1 files changed, 1722 insertions, 0 deletions

diff --git a/module/zfs/zvol.c b/module/zfs/zvol.c
new file mode 100644
index 000000000..4e993060c
--- /dev/null
+++ b/module/zfs/zvol.c
@@ -0,0 +1,1722 @@
+/*
+ * 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 2008 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+/*
+ * 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 ZFS-specific devfsadm link generator.
+ * 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/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_disk.h>
+#include <sys/vdev_impl.h>
+#include <sys/zvol.h>
+#include <sys/dumphdr.h>
+
+#include "zfs_namecheck.h"
+
+static void *zvol_state;
+
+#define	ZVOL_DUMPSIZE		"dumpsize"
+
+/*
+ * This lock protects the zvol_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.
+ */
+static kmutex_t zvol_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 */
+	objset_t	*zv_objset;	/* objset handle */
+	uint32_t	zv_mode;	/* DS_MODE_* flags at open time */
+	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 */
+	uint64_t	zv_txg_assign;	/* txg to assign during ZIL replay */
+	znode_t		zv_znode;	/* for range locking */
+} zvol_state_t;
+
+/*
+ * zvol specific flags
+ */
+#define	ZVOL_RDONLY	0x1
+#define	ZVOL_DUMPIFIED	0x2
+#define	ZVOL_EXCL	0x4
+
+/*
+ * zvol maximum transfer in one DMU tx.
+ */
+int zvol_maxphys = DMU_MAX_ACCESS/2;
+
+extern int zfs_set_prop_nvlist(const char *, nvlist_t *);
+static int zvol_get_data(void *arg, lr_write_t *lr, char *buf, 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, major_t maj)
+{
+	dev_t dev = makedevice(maj, zv->zv_minor);
+
+	VERIFY(ddi_prop_update_int64(dev, zfs_dip,
+	    "Size", zv->zv_volsize) == DDI_SUCCESS);
+	VERIFY(ddi_prop_update_int64(dev, zfs_dip,
+	    "Nblocks", lbtodb(zv->zv_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 (EINVAL);
+
+	if (volsize % blocksize != 0)
+		return (EINVAL);
+
+#ifdef _ILP32
+	if (volsize - 1 > SPEC_MAXOFFSET_T)
+		return (EOVERFLOW);
+#endif
+	return (0);
+}
+
+int
+zvol_check_volblocksize(uint64_t volblocksize)
+{
+	if (volblocksize < SPA_MINBLOCKSIZE ||
+	    volblocksize > SPA_MAXBLOCKSIZE ||
+	    !ISP2(volblocksize))
+		return (EDOM);
+
+	return (0);
+}
+
+static void
+zvol_readonly_changed_cb(void *arg, uint64_t newval)
+{
+	zvol_state_t *zv = arg;
+
+	if (newval)
+		zv->zv_flags |= ZVOL_RDONLY;
+	else
+		zv->zv_flags &= ~ZVOL_RDONLY;
+}
+
+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);
+}
+
+/*
+ * Find a free minor number.
+ */
+static minor_t
+zvol_minor_alloc(void)
+{
+	minor_t minor;
+
+	ASSERT(MUTEX_HELD(&zvol_state_lock));
+
+	for (minor = 1; minor <= ZVOL_MAX_MINOR; minor++)
+		if (ddi_get_soft_state(zvol_state, minor) == NULL)
+			return (minor);
+
+	return (0);
+}
+
+static zvol_state_t *
+zvol_minor_lookup(const char *name)
+{
+	minor_t minor;
+	zvol_state_t *zv;
+
+	ASSERT(MUTEX_HELD(&zvol_state_lock));
+
+	for (minor = 1; minor <= ZVOL_MAX_MINOR; minor++) {
+		zv = ddi_get_soft_state(zvol_state, minor);
+		if (zv == NULL)
+			continue;
+		if (strcmp(zv->zv_name, name) == 0)
+			break;
+	}
+
+	return (zv);
+}
+
+/* extent mapping arg */
+struct maparg {
+	zvol_state_t	*ma_zv;
+	uint64_t	ma_blks;
+};
+
+/*ARGSUSED*/
+static int
+zvol_map_block(spa_t *spa, blkptr_t *bp, const zbookmark_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 || zb->zb_object != ZVOL_OBJ || zb->zb_level != 0)
+		return (0);
+
+	VERIFY3U(ma->ma_blks, ==, zb->zb_blkid);
+	ma->ma_blks++;
+
+	/* Abort immediately if we have encountered gang blocks */
+	if (BP_IS_GANG(bp))
+		return (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)
+{
+	struct maparg	ma;
+	int		err;
+
+	ma.ma_zv = zv;
+	ma.ma_blks = 0;
+	zvol_free_extents(zv);
+
+	err = traverse_dataset(dmu_objset_ds(zv->zv_objset), 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_WRITE ZIL transaction that didn't get committed
+ * after a system failure
+ */
+static int
+zvol_replay_write(zvol_state_t *zv, lr_write_t *lr, boolean_t byteswap)
+{
+	objset_t *os = zv->zv_objset;
+	char *data = (char *)(lr + 1);	/* data follows lr_write_t */
+	uint64_t off = lr->lr_offset;
+	uint64_t len = lr->lr_length;
+	dmu_tx_t *tx;
+	int error;
+
+	if (byteswap)
+		byteswap_uint64_array(lr, sizeof (*lr));
+
+	tx = dmu_tx_create(os);
+	dmu_tx_hold_write(tx, ZVOL_OBJ, off, len);
+	error = dmu_tx_assign(tx, zv->zv_txg_assign);
+	if (error) {
+		dmu_tx_abort(tx);
+	} else {
+		dmu_write(os, ZVOL_OBJ, off, len, data, tx);
+		dmu_tx_commit(tx);
+	}
+
+	return (error);
+}
+
+/* ARGSUSED */
+static int
+zvol_replay_err(zvol_state_t *zv, lr_t *lr, boolean_t byteswap)
+{
+	return (ENOTSUP);
+}
+
+/*
+ * Callback vectors for replaying records.
+ * Only TX_WRITE is 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_err,	/* TX_TRUNCATE */
+	zvol_replay_err,	/* TX_SETATTR */
+	zvol_replay_err,	/* TX_ACL */
+};
+
+/*
+ * Create a minor node (plus a whole lot more) for the specified volume.
+ */
+int
+zvol_create_minor(const char *name, major_t maj)
+{
+	zvol_state_t *zv;
+	objset_t *os;
+	dmu_object_info_t doi;
+	uint64_t volsize;
+	minor_t minor = 0;
+	struct pathname linkpath;
+	int ds_mode = DS_MODE_OWNER;
+	vnode_t *vp = NULL;
+	char *devpath;
+	size_t devpathlen = strlen(ZVOL_FULL_DEV_DIR) + strlen(name) + 1;
+	char chrbuf[30], blkbuf[30];
+	int error;
+
+	mutex_enter(&zvol_state_lock);
+
+	if ((zv = zvol_minor_lookup(name)) != NULL) {
+		mutex_exit(&zvol_state_lock);
+		return (EEXIST);
+	}
+
+	if (strchr(name, '@') != 0)
+		ds_mode |= DS_MODE_READONLY;
+
+	error = dmu_objset_open(name, DMU_OST_ZVOL, ds_mode, &os);
+
+	if (error) {
+		mutex_exit(&zvol_state_lock);
+		return (error);
+	}
+
+	error = zap_lookup(os, ZVOL_ZAP_OBJ, "size", 8, 1, &volsize);
+
+	if (error) {
+		dmu_objset_close(os);
+		mutex_exit(&zvol_state_lock);
+		return (error);
+	}
+
+	/*
+	 * If there's an existing /dev/zvol symlink, try to use the
+	 * same minor number we used last time.
+	 */
+	devpath = kmem_alloc(devpathlen, KM_SLEEP);
+
+	(void) sprintf(devpath, "%s%s", ZVOL_FULL_DEV_DIR, name);
+
+	error = lookupname(devpath, UIO_SYSSPACE, NO_FOLLOW, NULL, &vp);
+
+	kmem_free(devpath, devpathlen);
+
+	if (error == 0 && vp->v_type != VLNK)
+		error = EINVAL;
+
+	if (error == 0) {
+		pn_alloc(&linkpath);
+		error = pn_getsymlink(vp, &linkpath, kcred);
+		if (error == 0) {
+			char *ms = strstr(linkpath.pn_path, ZVOL_PSEUDO_DEV);
+			if (ms != NULL) {
+				ms += strlen(ZVOL_PSEUDO_DEV);
+				minor = stoi(&ms);
+			}
+		}
+		pn_free(&linkpath);
+	}
+
+	if (vp != NULL)
+		VN_RELE(vp);
+
+	/*
+	 * If we found a minor but it's already in use, we must pick a new one.
+	 */
+	if (minor != 0 && ddi_get_soft_state(zvol_state, minor) != NULL)
+		minor = 0;
+
+	if (minor == 0)
+		minor = zvol_minor_alloc();
+
+	if (minor == 0) {
+		dmu_objset_close(os);
+		mutex_exit(&zvol_state_lock);
+		return (ENXIO);
+	}
+
+	if (ddi_soft_state_zalloc(zvol_state, minor) != DDI_SUCCESS) {
+		dmu_objset_close(os);
+		mutex_exit(&zvol_state_lock);
+		return (EAGAIN);
+	}
+
+	(void) ddi_prop_update_string(minor, zfs_dip, ZVOL_PROP_NAME,
+	    (char *)name);
+
+	(void) sprintf(chrbuf, "%uc,raw", minor);
+
+	if (ddi_create_minor_node(zfs_dip, chrbuf, S_IFCHR,
+	    minor, DDI_PSEUDO, 0) == DDI_FAILURE) {
+		ddi_soft_state_free(zvol_state, minor);
+		dmu_objset_close(os);
+		mutex_exit(&zvol_state_lock);
+		return (EAGAIN);
+	}
+
+	(void) sprintf(blkbuf, "%uc", 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(zvol_state, minor);
+		dmu_objset_close(os);
+		mutex_exit(&zvol_state_lock);
+		return (EAGAIN);
+	}
+
+	zv = ddi_get_soft_state(zvol_state, minor);
+
+	(void) strcpy(zv->zv_name, name);
+	zv->zv_min_bs = DEV_BSHIFT;
+	zv->zv_minor = minor;
+	zv->zv_volsize = volsize;
+	zv->zv_objset = os;
+	zv->zv_mode = ds_mode;
+	zv->zv_zilog = zil_open(os, zvol_get_data);
+	mutex_init(&zv->zv_znode.z_range_lock, NULL, MUTEX_DEFAULT, NULL);
+	avl_create(&zv->zv_znode.z_range_avl, zfs_range_compare,
+	    sizeof (rl_t), offsetof(rl_t, r_node));
+	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;
+
+	zil_replay(os, zv, &zv->zv_txg_assign, zvol_replay_vector, NULL);
+	zvol_size_changed(zv, maj);
+
+	/* XXX this should handle the possible i/o error */
+	VERIFY(dsl_prop_register(dmu_objset_ds(zv->zv_objset),
+	    "readonly", zvol_readonly_changed_cb, zv) == 0);
+
+	zvol_minors++;
+
+	mutex_exit(&zvol_state_lock);
+
+	return (0);
+}
+
+/*
+ * Remove minor node for the specified volume.
+ */
+int
+zvol_remove_minor(const char *name)
+{
+	zvol_state_t *zv;
+	char namebuf[30];
+
+	mutex_enter(&zvol_state_lock);
+
+	if ((zv = zvol_minor_lookup(name)) == NULL) {
+		mutex_exit(&zvol_state_lock);
+		return (ENXIO);
+	}
+
+	if (zv->zv_total_opens != 0) {
+		mutex_exit(&zvol_state_lock);
+		return (EBUSY);
+	}
+
+	(void) sprintf(namebuf, "%uc,raw", zv->zv_minor);
+	ddi_remove_minor_node(zfs_dip, namebuf);
+
+	(void) sprintf(namebuf, "%uc", zv->zv_minor);
+	ddi_remove_minor_node(zfs_dip, namebuf);
+
+	VERIFY(dsl_prop_unregister(dmu_objset_ds(zv->zv_objset),
+	    "readonly", zvol_readonly_changed_cb, zv) == 0);
+
+	zil_close(zv->zv_zilog);
+	zv->zv_zilog = NULL;
+	dmu_objset_close(zv->zv_objset);
+	zv->zv_objset = NULL;
+	avl_destroy(&zv->zv_znode.z_range_avl);
+	mutex_destroy(&zv->zv_znode.z_range_lock);
+
+	ddi_soft_state_free(zvol_state, zv->zv_minor);
+
+	zvol_minors--;
+
+	mutex_exit(&zvol_state_lock);
+
+	return (0);
+}
+
+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 (ENOSPC);
+
+	/* Free old extents if they exist */
+	zvol_free_extents(zv);
+
+	while (resid != 0) {
+		int error;
+		uint64_t bytes = MIN(resid, SPA_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);
+}
+
+int
+zvol_update_volsize(zvol_state_t *zv, major_t maj, uint64_t volsize)
+{
+	dmu_tx_t *tx;
+	int error;
+
+	ASSERT(MUTEX_HELD(&zvol_state_lock));
+
+	tx = dmu_tx_create(zv->zv_objset);
+	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);
+	}
+
+	error = zap_update(zv->zv_objset, ZVOL_ZAP_OBJ, "size", 8, 1,
+	    &volsize, tx);
+	dmu_tx_commit(tx);
+
+	if (error == 0)
+		error = dmu_free_long_range(zv->zv_objset,
+		    ZVOL_OBJ, volsize, DMU_OBJECT_END);
+
+	/*
+	 * If we are using a faked-up state (zv_minor == 0) then don't
+	 * try to update the in-core zvol state.
+	 */
+	if (error == 0 && zv->zv_minor) {
+		zv->zv_volsize = volsize;
+		zvol_size_changed(zv, maj);
+	}
+	return (error);
+}
+
+int
+zvol_set_volsize(const char *name, major_t maj, uint64_t volsize)
+{
+	zvol_state_t *zv;
+	int error;
+	dmu_object_info_t doi;
+	uint64_t old_volsize = 0ULL;
+	zvol_state_t state = { 0 };
+
+	mutex_enter(&zvol_state_lock);
+
+	if ((zv = zvol_minor_lookup(name)) == NULL) {
+		/*
+		 * If we are doing a "zfs clone -o volsize=", then the
+		 * minor node won't exist yet.
+		 */
+		error = dmu_objset_open(name, DMU_OST_ZVOL, DS_MODE_OWNER,
+		    &state.zv_objset);
+		if (error != 0)
+			goto out;
+		zv = &state;
+	}
+	old_volsize = zv->zv_volsize;
+
+	if ((error = dmu_object_info(zv->zv_objset, ZVOL_OBJ, &doi)) != 0 ||
+	    (error = zvol_check_volsize(volsize,
+	    doi.doi_data_block_size)) != 0)
+		goto out;
+
+	if (zv->zv_flags & ZVOL_RDONLY || (zv->zv_mode & DS_MODE_READONLY)) {
+		error = EROFS;
+		goto out;
+	}
+
+	error = zvol_update_volsize(zv, maj, volsize);
+
+	/*
+	 * Reinitialize the dump area to the new size. If we
+	 * failed to resize the dump area then restore the it back to
+	 * it's original size.
+	 */
+	if (error == 0 && zv->zv_flags & ZVOL_DUMPIFIED) {
+		if ((error = zvol_dumpify(zv)) != 0 ||
+		    (error = dumpvp_resize()) != 0) {
+			(void) zvol_update_volsize(zv, maj, old_volsize);
+			error = zvol_dumpify(zv);
+		}
+	}
+
+out:
+	if (state.zv_objset)
+		dmu_objset_close(state.zv_objset);
+
+	mutex_exit(&zvol_state_lock);
+
+	return (error);
+}
+
+int
+zvol_set_volblocksize(const char *name, uint64_t volblocksize)
+{
+	zvol_state_t *zv;
+	dmu_tx_t *tx;
+	int error;
+	boolean_t needlock;
+
+	/*
+	 * The lock may already be held if we are being called from
+	 * zvol_dump_init().
+	 */
+	needlock = !MUTEX_HELD(&zvol_state_lock);
+	if (needlock)
+		mutex_enter(&zvol_state_lock);
+
+	if ((zv = zvol_minor_lookup(name)) == NULL) {
+		if (needlock)
+			mutex_exit(&zvol_state_lock);
+		return (ENXIO);
+	}
+	if (zv->zv_flags & ZVOL_RDONLY || (zv->zv_mode & DS_MODE_READONLY)) {
+		if (needlock)
+			mutex_exit(&zvol_state_lock);
+		return (EROFS);
+	}
+
+	tx = dmu_tx_create(zv->zv_objset);
+	dmu_tx_hold_bonus(tx, ZVOL_OBJ);
+	error = dmu_tx_assign(tx, TXG_WAIT);
+	if (error) {
+		dmu_tx_abort(tx);
+	} else {
+		error = dmu_object_set_blocksize(zv->zv_objset, ZVOL_OBJ,
+		    volblocksize, 0, tx);
+		if (error == ENOTSUP)
+			error = EBUSY;
+		dmu_tx_commit(tx);
+		if (error == 0)
+			zv->zv_volblocksize = volblocksize;
+	}
+
+	if (needlock)
+		mutex_exit(&zvol_state_lock);
+
+	return (error);
+}
+
+/*ARGSUSED*/
+int
+zvol_open(dev_t *devp, int flag, int otyp, cred_t *cr)
+{
+	minor_t minor = getminor(*devp);
+	zvol_state_t *zv;
+
+	if (minor == 0)			/* This is the control device */
+		return (0);
+
+	mutex_enter(&zvol_state_lock);
+
+	zv = ddi_get_soft_state(zvol_state, minor);
+	if (zv == NULL) {
+		mutex_exit(&zvol_state_lock);
+		return (ENXIO);
+	}
+
+	ASSERT(zv->zv_objset != NULL);
+
+	if ((flag & FWRITE) &&
+	    (zv->zv_flags & ZVOL_RDONLY || (zv->zv_mode & DS_MODE_READONLY))) {
+		mutex_exit(&zvol_state_lock);
+		return (EROFS);
+	}
+	if (zv->zv_flags & ZVOL_EXCL) {
+		mutex_exit(&zvol_state_lock);
+		return (EBUSY);
+	}
+	if (flag & FEXCL) {
+		if (zv->zv_total_opens != 0) {
+			mutex_exit(&zvol_state_lock);
+			return (EBUSY);
+		}
+		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(&zvol_state_lock);
+
+	return (0);
+}
+
+/*ARGSUSED*/
+int
+zvol_close(dev_t dev, int flag, int otyp, cred_t *cr)
+{
+	minor_t minor = getminor(dev);
+	zvol_state_t *zv;
+
+	if (minor == 0)		/* This is the control device */
+		return (0);
+
+	mutex_enter(&zvol_state_lock);
+
+	zv = ddi_get_soft_state(zvol_state, minor);
+	if (zv == NULL) {
+		mutex_exit(&zvol_state_lock);
+		return (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--;
+
+	mutex_exit(&zvol_state_lock);
+
+	return (0);
+}
+
+static void
+zvol_get_done(dmu_buf_t *db, void *vzgd)
+{
+	zgd_t *zgd = (zgd_t *)vzgd;
+	rl_t *rl = zgd->zgd_rl;
+
+	dmu_buf_rele(db, vzgd);
+	zfs_range_unlock(rl);
+	zil_add_block(zgd->zgd_zilog, zgd->zgd_bp);
+	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, zio_t *zio)
+{
+	zvol_state_t *zv = arg;
+	objset_t *os = zv->zv_objset;
+	dmu_buf_t *db;
+	rl_t *rl;
+	zgd_t *zgd;
+	uint64_t boff; 			/* block starting offset */
+	int dlen = lr->lr_length;	/* length of user data */
+	int error;
+
+	ASSERT(zio);
+	ASSERT(dlen != 0);
+
+	/*
+	 * 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 */
+		return (dmu_read(os, ZVOL_OBJ, lr->lr_offset, dlen, buf));
+
+	zgd = (zgd_t *)kmem_alloc(sizeof (zgd_t), KM_SLEEP);
+	zgd->zgd_zilog = zv->zv_zilog;
+	zgd->zgd_bp = &lr->lr_blkptr;
+
+	/*
+	 * Lock the range of the block to ensure that when the data is
+	 * written out and its checksum is being calculated that no other
+	 * thread can change the block.
+	 */
+	boff = P2ALIGN_TYPED(lr->lr_offset, zv->zv_volblocksize, uint64_t);
+	rl = zfs_range_lock(&zv->zv_znode, boff, zv->zv_volblocksize,
+	    RL_READER);
+	zgd->zgd_rl = rl;
+
+	VERIFY(0 == dmu_buf_hold(os, ZVOL_OBJ, lr->lr_offset, zgd, &db));
+	error = dmu_sync(zio, db, &lr->lr_blkptr,
+	    lr->lr_common.lrc_txg, zvol_get_done, zgd);
+	if (error == 0)
+		zil_add_block(zv->zv_zilog, &lr->lr_blkptr);
+	/*
+	 * If we get EINPROGRESS, then we need to wait for a
+	 * write IO initiated by dmu_sync() to complete before
+	 * we can release this dbuf.  We will finish everything
+	 * up in the zvol_get_done() callback.
+	 */
+	if (error == EINPROGRESS)
+		return (0);
+	dmu_buf_rele(db, zgd);
+	zfs_range_unlock(rl);
+	kmem_free(zgd, sizeof (zgd_t));
+	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 len)
+{
+	uint32_t blocksize = zv->zv_volblocksize;
+	lr_write_t *lr;
+
+	while (len) {
+		ssize_t nbytes = MIN(len, blocksize - P2PHASE(off, blocksize));
+		itx_t *itx = zil_itx_create(TX_WRITE, sizeof (*lr));
+
+		itx->itx_wr_state =
+		    len > zvol_immediate_write_sz ?  WR_INDIRECT : WR_NEED_COPY;
+		itx->itx_private = zv;
+		lr = (lr_write_t *)&itx->itx_lr;
+		lr->lr_foid = ZVOL_OBJ;
+		lr->lr_offset = off;
+		lr->lr_length = nbytes;
+		lr->lr_blkoff = off - P2ALIGN_TYPED(off, blocksize, uint64_t);
+		BP_ZERO(&lr->lr_blkptr);
+
+		(void) zil_itx_assign(zv->zv_zilog, itx, tx);
+		len -= nbytes;
+		off += nbytes;
+	}
+}
+
+static int
+zvol_dumpio_vdev(vdev_t *vd, void *addr, uint64_t offset, uint64_t size,
+    boolean_t doread, boolean_t isdump)
+{
+	vdev_disk_t *dvd;
+	int c;
+	int numerrors = 0;
+
+	for (c = 0; c < vd->vdev_children; c++) {
+		ASSERT(vd->vdev_ops == &vdev_mirror_ops);
+		int err = zvol_dumpio_vdev(vd->vdev_child[c],
+		    addr, offset, size, doread, isdump);
+		if (err != 0) {
+			numerrors++;
+		} else if (doread) {
+			break;
+		}
+	}
+
+	if (!vd->vdev_ops->vdev_op_leaf)
+		return (numerrors < vd->vdev_children ? 0 : EIO);
+
+	if (doread && !vdev_readable(vd))
+		return (EIO);
+	else if (!doread && !vdev_writeable(vd))
+		return (EIO);
+
+	dvd = vd->vdev_tsd;
+	ASSERT3P(dvd, !=, NULL);
+	offset += VDEV_LABEL_START_SIZE;
+
+	if (ddi_in_panic() || isdump) {
+		ASSERT(!doread);
+		if (doread)
+			return (EIO);
+		return (ldi_dump(dvd->vd_lh, addr, lbtodb(offset),
+		    lbtodb(size)));
+	} else {
+		return (vdev_disk_physio(dvd->vd_lh, addr, size, offset,
+		    doread ? B_READ : B_WRITE));
+	}
+}
+
+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 (EINVAL);
+	}
+	ASSERT(size <= zv->zv_volblocksize);
+
+	/* Locate the extent this belongs to */
+	ze = list_head(&zv->zv_extents);
+	while (offset >= ze->ze_nblks * zv->zv_volblocksize) {
+		offset -= ze->ze_nblks * zv->zv_volblocksize;
+		ze = list_next(&zv->zv_extents, ze);
+	}
+	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, size, doread, isdump);
+	spa_config_exit(spa, SCL_STATE, FTAG);
+	return (error);
+}
+
+int
+zvol_strategy(buf_t *bp)
+{
+	zvol_state_t *zv = ddi_get_soft_state(zvol_state, getminor(bp->b_edev));
+	uint64_t off, volsize;
+	size_t resid;
+	char *addr;
+	objset_t *os;
+	rl_t *rl;
+	int error = 0;
+	boolean_t doread = bp->b_flags & B_READ;
+	boolean_t is_dump = zv->zv_flags & ZVOL_DUMPIFIED;
+
+	if (zv == NULL) {
+		bioerror(bp, ENXIO);
+		biodone(bp);
+		return (0);
+	}
+
+	if (getminor(bp->b_edev) == 0) {
+		bioerror(bp, EINVAL);
+		biodone(bp);
+		return (0);
+	}
+
+	if (!(bp->b_flags & B_READ) &&
+	    (zv->zv_flags & ZVOL_RDONLY ||
+	    zv->zv_mode & DS_MODE_READONLY)) {
+		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 < 0 || off >= volsize)) {
+		bioerror(bp, EIO);
+		biodone(bp);
+		return (0);
+	}
+
+	/*
+	 * There must be no buffer changes when doing a dmu_sync() because
+	 * we can't change the data whilst calculating the checksum.
+	 */
+	rl = zfs_range_lock(&zv->zv_znode, off, resid,
+	    doread ? RL_READER : RL_WRITER);
+
+	while (resid != 0 && off < volsize) {
+		size_t size = MIN(resid, zvol_maxphys);
+		if (is_dump) {
+			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);
+		} 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);
+				dmu_tx_commit(tx);
+			}
+		}
+		if (error) {
+			/* convert checksum errors into IO errors */
+			if (error == ECKSUM)
+				error = EIO;
+			break;
+		}
+		off += size;
+		addr += size;
+		resid -= size;
+	}
+	zfs_range_unlock(rl);
+
+	if ((bp->b_resid = resid) == bp->b_bcount)
+		bioerror(bp, off > volsize ? EINVAL : error);
+
+	if (!(bp->b_flags & B_ASYNC) && !doread && !zil_disable && !is_dump)
+		zil_commit(zv->zv_zilog, UINT64_MAX, ZVOL_OBJ);
+	biodone(bp);
+
+	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;
+
+	if (minor == 0)			/* This is the control device */
+		return (ENXIO);
+
+	zv = ddi_get_soft_state(zvol_state, minor);
+	if (zv == NULL)
+		return (ENXIO);
+
+	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;
+	rl_t *rl;
+	int error = 0;
+
+	if (minor == 0)			/* This is the control device */
+		return (ENXIO);
+
+	zv = ddi_get_soft_state(zvol_state, minor);
+	if (zv == NULL)
+		return (ENXIO);
+
+	volsize = zv->zv_volsize;
+	if (uio->uio_resid > 0 &&
+	    (uio->uio_loffset < 0 || uio->uio_loffset >= volsize))
+		return (EIO);
+
+	if (zv->zv_flags & ZVOL_DUMPIFIED) {
+		error = physio(zvol_strategy, NULL, dev, B_READ,
+		    zvol_minphys, uio);
+		return (error);
+	}
+
+	rl = zfs_range_lock(&zv->zv_znode, 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 = EIO;
+			break;
+		}
+	}
+	zfs_range_unlock(rl);
+	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;
+	rl_t *rl;
+	int error = 0;
+
+	if (minor == 0)			/* This is the control device */
+		return (ENXIO);
+
+	zv = ddi_get_soft_state(zvol_state, minor);
+	if (zv == NULL)
+		return (ENXIO);
+
+	volsize = zv->zv_volsize;
+	if (uio->uio_resid > 0 &&
+	    (uio->uio_loffset < 0 || uio->uio_loffset >= volsize))
+		return (EIO);
+
+	if (zv->zv_flags & ZVOL_DUMPIFIED) {
+		error = physio(zvol_strategy, NULL, dev, B_WRITE,
+		    zvol_minphys, uio);
+		return (error);
+	}
+
+	rl = zfs_range_lock(&zv->zv_znode, 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(tx, ZVOL_OBJ, off, bytes);
+		error = dmu_tx_assign(tx, TXG_WAIT);
+		if (error) {
+			dmu_tx_abort(tx);
+			break;
+		}
+		error = dmu_write_uio(zv->zv_objset, ZVOL_OBJ, uio, bytes, tx);
+		if (error == 0)
+			zvol_log_write(zv, tx, off, bytes);
+		dmu_tx_commit(tx);
+
+		if (error)
+			break;
+	}
+	zfs_range_unlock(rl);
+	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 (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 (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(sizeof (gpt));
+		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, sizeof (gpt), -1U, crc32_table);
+		gpt.efi_gpt_HeaderCRC32 = LE_32(~crc);
+		if (ddi_copyout(&gpt, ptr, MIN(sizeof (gpt), length),
+		    flag))
+			return (EFAULT);
+		ptr += sizeof (gpt);
+		length -= sizeof (gpt);
+	}
+	if (length > 0 && ddi_copyout(&gpe, ptr, MIN(sizeof (gpe),
+	    length), flag))
+		return (EFAULT);
+	return (0);
+}
+
+/*
+ * Dirtbag ioctls to support mkfs(1M) for UFS filesystems.  See dkio(7I).
+ */
+/*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_cinfo dki;
+	struct dk_minfo dkm;
+	struct dk_callback *dkc;
+	int error = 0;
+	rl_t *rl;
+
+	mutex_enter(&zvol_state_lock);
+
+	zv = ddi_get_soft_state(zvol_state, getminor(dev));
+
+	if (zv == NULL) {
+		mutex_exit(&zvol_state_lock);
+		return (ENXIO);
+	}
+
+	switch (cmd) {
+
+	case DKIOCINFO:
+		bzero(&dki, sizeof (dki));
+		(void) strcpy(dki.dki_cname, "zvol");
+		(void) strcpy(dki.dki_dname, "zvol");
+		dki.dki_ctype = DKC_UNKNOWN;
+		dki.dki_maxtransfer = 1 << (SPA_MAXBLOCKSHIFT - zv->zv_min_bs);
+		mutex_exit(&zvol_state_lock);
+		if (ddi_copyout(&dki, (void *)arg, sizeof (dki), flag))
+			error = EFAULT;
+		return (error);
+
+	case DKIOCGMEDIAINFO:
+		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(&zvol_state_lock);
+		if (ddi_copyout(&dkm, (void *)arg, sizeof (dkm), flag))
+			error = EFAULT;
+		return (error);
+
+	case DKIOCGETEFI:
+		{
+			uint64_t vs = zv->zv_volsize;
+			uint8_t bs = zv->zv_min_bs;
+
+			mutex_exit(&zvol_state_lock);
+			error = zvol_getefi((void *)arg, flag, vs, bs);
+			return (error);
+		}
+
+	case DKIOCFLUSHWRITECACHE:
+		dkc = (struct dk_callback *)arg;
+		zil_commit(zv->zv_zilog, UINT64_MAX, ZVOL_OBJ);
+		if ((flag & FKIOCTL) && dkc != NULL && dkc->dkc_callback) {
+			(*dkc->dkc_callback)(dkc->dkc_cookie, error);
+			error = 0;
+		}
+		break;
+
+	case DKIOCGGEOM:
+	case DKIOCGVTOC:
+		/*
+		 * commands using these (like prtvtoc) expect ENOTSUP
+		 * since we're emulating an EFI label
+		 */
+		error = ENOTSUP;
+		break;
+
+	case DKIOCDUMPINIT:
+		rl = zfs_range_lock(&zv->zv_znode, 0, zv->zv_volsize,
+		    RL_WRITER);
+		error = zvol_dumpify(zv);
+		zfs_range_unlock(rl);
+		break;
+
+	case DKIOCDUMPFINI:
+		rl = zfs_range_lock(&zv->zv_znode, 0, zv->zv_volsize,
+		    RL_WRITER);
+		error = zvol_dump_fini(zv);
+		zfs_range_unlock(rl);
+		break;
+
+	default:
+		error = ENOTTY;
+		break;
+
+	}
+	mutex_exit(&zvol_state_lock);
+	return (error);
+}
+
+int
+zvol_busy(void)
+{
+	return (zvol_minors != 0);
+}
+
+void
+zvol_init(void)
+{
+	VERIFY(ddi_soft_state_init(&zvol_state, sizeof (zvol_state_t), 1) == 0);
+	mutex_init(&zvol_state_lock, NULL, MUTEX_DEFAULT, NULL);
+}
+
+void
+zvol_fini(void)
+{
+	mutex_destroy(&zvol_state_lock);
+	ddi_soft_state_fini(&zvol_state);
+}
+
+static boolean_t
+zvol_is_swap(zvol_state_t *zv)
+{
+	vnode_t *vp;
+	boolean_t ret = B_FALSE;
+	char *devpath;
+	size_t devpathlen;
+	int error;
+
+	devpathlen = strlen(ZVOL_FULL_DEV_DIR) + strlen(zv->zv_name) + 1;
+	devpath = kmem_alloc(devpathlen, KM_SLEEP);
+	(void) sprintf(devpath, "%s%s", ZVOL_FULL_DEV_DIR, zv->zv_name);
+	error = lookupname(devpath, UIO_SYSSPACE, FOLLOW, NULLVPP, &vp);
+	kmem_free(devpath, devpathlen);
+
+	ret = !error && IS_SWAPVP(common_specvp(vp));
+
+	if (vp != NULL)
+		VN_RELE(vp);
+
+	return (ret);
+}
+
+static int
+zvol_dump_init(zvol_state_t *zv, boolean_t resize)
+{
+	dmu_tx_t *tx;
+	int error = 0;
+	objset_t *os = zv->zv_objset;
+	nvlist_t *nv = NULL;
+
+	ASSERT(MUTEX_HELD(&zvol_state_lock));
+
+	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);
+	}
+
+	/*
+	 * 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 {
+		uint64_t checksum, compress, refresrv, vbs;
+
+		error = dsl_prop_get_integer(zv->zv_name,
+		    zfs_prop_to_name(ZFS_PROP_COMPRESSION), &compress, NULL);
+		error = error ? error : dsl_prop_get_integer(zv->zv_name,
+		    zfs_prop_to_name(ZFS_PROP_CHECKSUM), &checksum, NULL);
+		error = error ? error : dsl_prop_get_integer(zv->zv_name,
+		    zfs_prop_to_name(ZFS_PROP_REFRESERVATION), &refresrv, NULL);
+		error = error ? error : dsl_prop_get_integer(zv->zv_name,
+		    zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), &vbs, NULL);
+
+		error = error ? error : zap_update(os, ZVOL_ZAP_OBJ,
+		    zfs_prop_to_name(ZFS_PROP_COMPRESSION), 8, 1,
+		    &compress, tx);
+		error = error ? error : zap_update(os, ZVOL_ZAP_OBJ,
+		    zfs_prop_to_name(ZFS_PROP_CHECKSUM), 8, 1, &checksum, tx);
+		error = error ? error : zap_update(os, ZVOL_ZAP_OBJ,
+		    zfs_prop_to_name(ZFS_PROP_REFRESERVATION), 8, 1,
+		    &refresrv, tx);
+		error = error ? error : zap_update(os, ZVOL_ZAP_OBJ,
+		    zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), 8, 1,
+		    &vbs, tx);
+	}
+	dmu_tx_commit(tx);
+
+	/* Truncate the file */
+	if (!error)
+		error = dmu_free_long_range(zv->zv_objset,
+		    ZVOL_OBJ, 0, DMU_OBJECT_END);
+
+	if (error)
+		return (error);
+
+	/*
+	 * We only need update the zvol's property if we are initializing
+	 * the dump area for the first time.
+	 */
+	if (!resize) {
+		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),
+		    ZIO_CHECKSUM_OFF) == 0);
+		VERIFY(nvlist_add_uint64(nv,
+		    zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE),
+		    SPA_MAXBLOCKSIZE) == 0);
+
+		error = zfs_set_prop_nvlist(zv->zv_name, nv);
+		nvlist_free(nv);
+
+		if (error)
+			return (error);
+	}
+
+	/* Allocate the space for the dump */
+	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 || (zv->zv_mode & DS_MODE_READONLY))
+		return (EROFS);
+
+	/*
+	 * We do not support swap devices acting as dump devices.
+	 */
+	if (zvol_is_swap(zv))
+		return (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) ? B_TRUE : B_FALSE;
+
+		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;
+
+	/*
+	 * 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);
+	(void) nvlist_add_uint64(nv,
+	    zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), vbs);
+	(void) zfs_set_prop_nvlist(zv->zv_name, nv);
+	nvlist_free(nv);
+
+	zvol_free_extents(zv);
+	zv->zv_flags &= ~ZVOL_DUMPIFIED;
+	(void) dmu_free_long_range(os, ZVOL_OBJ, 0, DMU_OBJECT_END);
+
+	return (0);
+}