Update ZFS from version 6 to 13 and bring some FreeBSD-specific changes.

This bring huge amount of changes, I'll enumerate only user-visible changes:

- Delegated Administration

	Allows regular users to perform ZFS operations, like file system
	creation, snapshot creation, etc.

- L2ARC

	Level 2 cache for ZFS - allows to use additional disks for cache.
	Huge performance improvements mostly for random read of mostly
	static content.

- slog

	Allow to use additional disks for ZFS Intent Log to speed up
	operations like fsync(2).

- vfs.zfs.super_owner

	Allows regular users to perform privileged operations on files stored
	on ZFS file systems owned by him. Very careful with this one.

- chflags(2)

	Not all the flags are supported. This still needs work.

- ZFSBoot

	Support to boot off of ZFS pool. Not finished, AFAIK.

	Submitted by:	dfr

- Snapshot properties

- New failure modes

	Before if write requested failed, system paniced. Now one
	can select from one of three failure modes:
	- panic - panic on write error
	- wait - wait for disk to reappear
	- continue - serve read requests if possible, block write requests

- Refquota, refreservation properties

	Just quota and reservation properties, but don't count space consumed
	by children file systems, clones and snapshots.

- Sparse volumes

	ZVOLs that don't reserve space in the pool.

- External attributes

	Compatible with extattr(2).

- NFSv4-ACLs

	Not sure about the status, might not be complete yet.

	Submitted by:	trasz

- Creation-time properties

- Regression tests for zpool(8) command.

Obtained from:	OpenSolaris

1 files changed, 1443 insertions, 0 deletions

diff --git a/sys/boot/zfs/zfsimpl.c b/sys/boot/zfs/zfsimpl.c
new file mode 100644
index 0000000..5bbc351
--- /dev/null
+++ b/sys/boot/zfs/zfsimpl.c
@@ -0,0 +1,1443 @@
+/*-
+ * Copyright (c) 2007 Doug Rabson
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+/*
+ *	Stand-alone ZFS file reader.
+ */
+
+#include "zfsimpl.h"
+#include "zfssubr.c"
+
+/*
+ * List of all vdevs, chained through v_alllink.
+ */
+static vdev_list_t zfs_vdevs;
+
+/*
+ * List of all pools, chained through spa_link.
+ */
+static spa_list_t zfs_pools;
+
+static uint64_t zfs_crc64_table[256];
+static char *zfs_decomp_buf;
+static const dnode_phys_t *dnode_cache_obj = 0;
+static uint64_t dnode_cache_bn;
+static char *dnode_cache_buf;
+static char *zap_scratch;
+
+/*
+ * Forward declarations.
+ */
+static int zio_read_phys(vdev_t *vdev, const blkptr_t *bp, void *buf, off_t offset);
+
+static void
+zfs_init(void)
+{
+	STAILQ_INIT(&zfs_vdevs);
+	STAILQ_INIT(&zfs_pools);
+
+	zfs_decomp_buf = malloc(128*1024);
+	dnode_cache_buf = malloc(128*1024);
+	zap_scratch = malloc(128*1024);
+
+	zfs_init_crc();
+}
+
+static int
+xdr_int(const unsigned char **xdr, int *ip)
+{
+	*ip = ((*xdr)[0] << 24)
+		| ((*xdr)[1] << 16)
+		| ((*xdr)[2] << 8)
+		| ((*xdr)[3] << 0);
+	(*xdr) += 4;
+	return (0);
+}
+
+static int
+xdr_u_int(const unsigned char **xdr, u_int *ip)
+{
+	*ip = ((*xdr)[0] << 24)
+		| ((*xdr)[1] << 16)
+		| ((*xdr)[2] << 8)
+		| ((*xdr)[3] << 0);
+	(*xdr) += 4;
+	return (0);
+}
+
+static int
+xdr_uint64_t(const unsigned char **xdr, uint64_t *lp)
+{
+	u_int hi, lo;
+
+	xdr_u_int(xdr, &hi);
+	xdr_u_int(xdr, &lo);
+	*lp = (((uint64_t) hi) << 32) | lo;
+	return (0);
+}
+
+static int
+nvlist_find(const unsigned char *nvlist, const char *name, int type,
+	    int* elementsp, void *valuep)
+{
+	const unsigned char *p, *pair;
+	int junk;
+	int encoded_size, decoded_size;
+
+	p = nvlist;
+	xdr_int(&p, &junk);
+	xdr_int(&p, &junk);
+
+	pair = p;
+	xdr_int(&p, &encoded_size);
+	xdr_int(&p, &decoded_size);
+	while (encoded_size && decoded_size) {
+		int namelen, pairtype, elements;
+		const char *pairname;
+
+		xdr_int(&p, &namelen);
+		pairname = (const char*) p;
+		p += roundup(namelen, 4);
+		xdr_int(&p, &pairtype);
+
+		if (!memcmp(name, pairname, namelen) && type == pairtype) {
+			xdr_int(&p, &elements);
+			if (elementsp)
+				*elementsp = elements;
+			if (type == DATA_TYPE_UINT64) {
+				xdr_uint64_t(&p, (uint64_t *) valuep);
+				return (0);
+			} else if (type == DATA_TYPE_STRING) {
+				int len;
+				xdr_int(&p, &len);
+				(*(const char**) valuep) = (const char*) p;
+				return (0);
+			} else if (type == DATA_TYPE_NVLIST
+				   || type == DATA_TYPE_NVLIST_ARRAY) {
+				(*(const unsigned char**) valuep) =
+					 (const unsigned char*) p;
+				return (0);
+			} else {
+				return (EIO);
+			}
+		} else {
+			/*
+			 * Not the pair we are looking for, skip to the next one.
+			 */
+			p = pair + encoded_size;
+		}
+
+		pair = p;
+		xdr_int(&p, &encoded_size);
+		xdr_int(&p, &decoded_size);
+	}
+
+	return (EIO);
+}
+
+/*
+ * Return the next nvlist in an nvlist array.
+ */
+static const unsigned char *
+nvlist_next(const unsigned char *nvlist)
+{
+	const unsigned char *p, *pair;
+	int junk;
+	int encoded_size, decoded_size;
+
+	p = nvlist;
+	xdr_int(&p, &junk);
+	xdr_int(&p, &junk);
+
+	pair = p;
+	xdr_int(&p, &encoded_size);
+	xdr_int(&p, &decoded_size);
+	while (encoded_size && decoded_size) {
+		p = pair + encoded_size;
+
+		pair = p;
+		xdr_int(&p, &encoded_size);
+		xdr_int(&p, &decoded_size);
+	}
+
+	return p;
+}
+
+#ifdef TEST
+
+static const unsigned char *
+nvlist_print(const unsigned char *nvlist, unsigned int indent)
+{
+	static const char* typenames[] = {
+		"DATA_TYPE_UNKNOWN",
+		"DATA_TYPE_BOOLEAN",
+		"DATA_TYPE_BYTE",
+		"DATA_TYPE_INT16",
+		"DATA_TYPE_UINT16",
+		"DATA_TYPE_INT32",
+		"DATA_TYPE_UINT32",
+		"DATA_TYPE_INT64",
+		"DATA_TYPE_UINT64",
+		"DATA_TYPE_STRING",
+		"DATA_TYPE_BYTE_ARRAY",
+		"DATA_TYPE_INT16_ARRAY",
+		"DATA_TYPE_UINT16_ARRAY",
+		"DATA_TYPE_INT32_ARRAY",
+		"DATA_TYPE_UINT32_ARRAY",
+		"DATA_TYPE_INT64_ARRAY",
+		"DATA_TYPE_UINT64_ARRAY",
+		"DATA_TYPE_STRING_ARRAY",
+		"DATA_TYPE_HRTIME",
+		"DATA_TYPE_NVLIST",
+		"DATA_TYPE_NVLIST_ARRAY",
+		"DATA_TYPE_BOOLEAN_VALUE",
+		"DATA_TYPE_INT8",
+		"DATA_TYPE_UINT8",
+		"DATA_TYPE_BOOLEAN_ARRAY",
+		"DATA_TYPE_INT8_ARRAY",
+		"DATA_TYPE_UINT8_ARRAY"
+	};
+
+	unsigned int i, j;
+	const unsigned char *p, *pair;
+	int junk;
+	int encoded_size, decoded_size;
+
+	p = nvlist;
+	xdr_int(&p, &junk);
+	xdr_int(&p, &junk);
+
+	pair = p;
+	xdr_int(&p, &encoded_size);
+	xdr_int(&p, &decoded_size);
+	while (encoded_size && decoded_size) {
+		int namelen, pairtype, elements;
+		const char *pairname;
+
+		xdr_int(&p, &namelen);
+		pairname = (const char*) p;
+		p += roundup(namelen, 4);
+		xdr_int(&p, &pairtype);
+
+		for (i = 0; i < indent; i++)
+			printf(" ");
+		printf("%s %s", typenames[pairtype], pairname);
+
+		xdr_int(&p, &elements);
+		switch (pairtype) {
+		case DATA_TYPE_UINT64: {
+			uint64_t val;
+			xdr_uint64_t(&p, &val);
+			printf(" = 0x%llx\n", val);
+			break;
+		}
+
+		case DATA_TYPE_STRING: {
+			int len;
+			xdr_int(&p, &len);
+			printf(" = \"%s\"\n", p);
+			break;
+		}
+
+		case DATA_TYPE_NVLIST:
+			printf("\n");
+			nvlist_print(p, indent + 1);
+			break;
+
+		case DATA_TYPE_NVLIST_ARRAY:
+			for (j = 0; j < elements; j++) {
+				printf("[%d]\n", j);
+				p = nvlist_print(p, indent + 1);
+				if (j != elements - 1) {
+					for (i = 0; i < indent; i++)
+						printf(" ");
+					printf("%s %s", typenames[pairtype], pairname);
+				}
+			}
+			break;
+
+		default:
+			printf("\n");
+		}
+
+		p = pair + encoded_size;
+
+		pair = p;
+		xdr_int(&p, &encoded_size);
+		xdr_int(&p, &decoded_size);
+	}
+
+	return p;
+}
+
+#endif
+
+static int
+vdev_mirror_read(vdev_t *vdev, void *priv, off_t offset, void *buf, size_t size)
+{
+	vdev_t *kid;
+	int rc;
+
+	rc = EIO;
+	STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) {
+		if (kid->v_state != VDEV_STATE_HEALTHY)
+			continue;
+		rc = kid->v_read(kid, kid->v_read_priv, offset, buf, size);
+		if (!rc)
+			return (0);
+	}
+
+	return (rc);
+}
+
+static vdev_t *
+vdev_find(uint64_t guid)
+{
+	vdev_t *vdev;
+
+	STAILQ_FOREACH(vdev, &zfs_vdevs, v_alllink)
+		if (vdev->v_guid == guid)
+			return (vdev);
+
+	return (0);
+}
+
+static vdev_t *
+vdev_create(uint64_t guid, vdev_read_t *read, void *read_priv)
+{
+	vdev_t *vdev;
+
+	vdev = malloc(sizeof(vdev_t));
+	memset(vdev, 0, sizeof(vdev_t));
+	STAILQ_INIT(&vdev->v_children);
+	vdev->v_guid = guid;
+	vdev->v_state = VDEV_STATE_OFFLINE;
+	vdev->v_read = read;
+	vdev->v_read_priv = read_priv;
+	STAILQ_INSERT_TAIL(&zfs_vdevs, vdev, v_alllink);
+
+	return (vdev);
+}
+
+static int
+vdev_init_from_nvlist(const unsigned char *nvlist, vdev_t **vdevp)
+{
+	int rc;
+	uint64_t guid, id;
+	const char *type;
+	const char *path;
+	vdev_t *vdev, *kid;
+	const unsigned char *kids;
+	int nkids, i;
+
+	if (nvlist_find(nvlist, ZPOOL_CONFIG_GUID,
+			DATA_TYPE_UINT64, 0, &guid)
+	    || nvlist_find(nvlist, ZPOOL_CONFIG_ID,
+			   DATA_TYPE_UINT64, 0, &id)
+	    || nvlist_find(nvlist, ZPOOL_CONFIG_TYPE,
+			   DATA_TYPE_STRING, 0, &type)) {
+		printf("ZFS: can't find vdev details\n");
+		return (ENOENT);
+	}
+
+	/*
+	 * Assume that if we've seen this vdev tree before, this one
+	 * will be identical.
+	 */
+	vdev = vdev_find(guid);
+	if (vdev) {
+		if (vdevp)
+			*vdevp = vdev;
+		return (0);
+	}
+
+	if (strcmp(type, VDEV_TYPE_MIRROR)
+	    && strcmp(type, VDEV_TYPE_DISK)) {
+		printf("ZFS: can only boot from disk or mirror vdevs\n");
+		return (EIO);
+	}
+
+	if (!strcmp(type, VDEV_TYPE_MIRROR))
+		vdev = vdev_create(guid, vdev_mirror_read, 0);
+	else
+		vdev = vdev_create(guid, 0, 0);
+
+
+	if (nvlist_find(nvlist, ZPOOL_CONFIG_PATH,
+			DATA_TYPE_STRING, 0, &path) == 0) {
+		if (strlen(path) > 5
+		    && path[0] == '/'
+		    && path[1] == 'd'
+		    && path[2] == 'e'
+		    && path[3] == 'v'
+		    && path[4] == '/')
+			path += 5;
+		vdev->v_name = strdup(path);
+	} else {
+		vdev->v_name = strdup(type);
+	}
+	vdev->v_id = id;
+	rc = nvlist_find(nvlist, ZPOOL_CONFIG_CHILDREN,
+			 DATA_TYPE_NVLIST_ARRAY, &nkids, &kids);
+	/*
+	 * Its ok if we don't have any kids.
+	 */
+	if (rc == 0) {
+		for (i = 0; i < nkids; i++) {
+			rc = vdev_init_from_nvlist(kids, &kid);
+			if (rc)
+				return (rc);
+			STAILQ_INSERT_TAIL(&vdev->v_children, kid, v_childlink);
+			kids = nvlist_next(kids);
+		}
+	}
+
+	if (vdevp)
+		*vdevp = vdev;
+	return (0);
+}
+
+static void
+vdev_set_state(vdev_t *vdev)
+{
+	vdev_t *kid;
+	int good_kids;
+	int bad_kids;
+
+	/*
+	 * We assume that if we have kids, we are a mirror. A mirror
+	 * is healthy if all its kids are healthy. Its degraded (but
+	 * working) if at least one kid is healty.
+	 */
+
+	if (STAILQ_FIRST(&vdev->v_children)) {
+		good_kids = 0;
+		bad_kids = 0;
+		STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) {
+			if (kid->v_state == VDEV_STATE_HEALTHY)
+				good_kids++;
+			else
+				bad_kids++;
+		}
+		if (good_kids) {
+			if (!bad_kids && good_kids)
+				vdev->v_state = VDEV_STATE_HEALTHY;
+			else
+				vdev->v_state = VDEV_STATE_DEGRADED;
+		} else {
+			vdev->v_state = VDEV_STATE_OFFLINE;
+		}
+	}
+}
+
+static spa_t *
+spa_find_by_guid(uint64_t guid)
+{
+	spa_t *spa;
+
+	STAILQ_FOREACH(spa, &zfs_pools, spa_link)
+		if (spa->spa_guid == guid)
+			return (spa);
+
+	return (0);
+}
+
+#ifdef BOOT2
+
+static spa_t *
+spa_find_by_name(const char *name)
+{
+	spa_t *spa;
+
+	STAILQ_FOREACH(spa, &zfs_pools, spa_link)
+		if (!strcmp(spa->spa_name, name))
+			return (spa);
+
+	return (0);
+}
+
+#endif
+
+static spa_t *
+spa_create(uint64_t guid)
+{
+	spa_t *spa;
+
+	spa = malloc(sizeof(spa_t));
+	memset(spa, 0, sizeof(spa_t));
+	STAILQ_INIT(&spa->spa_vdevs);
+	spa->spa_guid = guid;
+	STAILQ_INSERT_TAIL(&zfs_pools, spa, spa_link);
+
+	return (spa);
+}
+
+static const char *
+state_name(vdev_state_t state)
+{
+	static const char* names[] = {
+		"UNKNOWN",
+		"CLOSED",
+		"OFFLINE",
+		"CANT_OPEN",
+		"DEGRADED",
+		"ONLINE"
+	};
+	return names[state];
+}
+
+#ifdef BOOT2
+
+#define pager_printf printf
+
+#else
+
+static void
+pager_printf(const char *fmt, ...)
+{
+	char line[80];
+	va_list args;
+
+	va_start(args, fmt);
+	vsprintf(line, fmt, args);
+	va_end(args);
+	pager_output(line);
+}
+
+#endif
+
+#define STATUS_FORMAT	"        %-16s %-10s\n"
+
+static void
+print_state(int indent, const char *name, vdev_state_t state)
+{
+	int i;
+	char buf[512];
+
+	buf[0] = 0;
+	for (i = 0; i < indent; i++)
+		strcat(buf, "  ");
+	strcat(buf, name);
+	pager_printf(STATUS_FORMAT, buf, state_name(state));
+	
+}
+
+static void
+vdev_status(vdev_t *vdev, int indent)
+{
+	vdev_t *kid;
+	print_state(indent, vdev->v_name, vdev->v_state);
+
+	STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) {
+		vdev_status(kid, indent + 1);
+	}
+}
+
+static void
+spa_status(spa_t *spa)
+{
+	vdev_t *vdev;
+	int good_kids, bad_kids, degraded_kids;
+	vdev_state_t state;
+
+	pager_printf("  pool: %s\n", spa->spa_name);
+	pager_printf("config:\n\n");
+	pager_printf(STATUS_FORMAT, "NAME", "STATE");
+
+	good_kids = 0;
+	degraded_kids = 0;
+	bad_kids = 0;
+	STAILQ_FOREACH(vdev, &spa->spa_vdevs, v_childlink) {
+		if (vdev->v_state == VDEV_STATE_HEALTHY)
+			good_kids++;
+		else if (vdev->v_state == VDEV_STATE_DEGRADED)
+			degraded_kids++;
+		else
+			bad_kids++;
+	}
+
+	state = VDEV_STATE_CLOSED;
+	if (good_kids > 0 && (degraded_kids + bad_kids) == 0)
+		state = VDEV_STATE_HEALTHY;
+	else if ((good_kids + degraded_kids) > 0)
+		state = VDEV_STATE_DEGRADED;
+
+	print_state(0, spa->spa_name, state);
+	STAILQ_FOREACH(vdev, &spa->spa_vdevs, v_childlink) {
+		vdev_status(vdev, 1);
+	}
+}
+
+static void
+spa_all_status(void)
+{
+	spa_t *spa;
+	int first = 1;
+
+	STAILQ_FOREACH(spa, &zfs_pools, spa_link) {
+		if (!first)
+			pager_printf("\n");
+		first = 0;
+		spa_status(spa);
+	}
+}
+
+static int
+vdev_probe(vdev_read_t *read, void *read_priv, spa_t **spap)
+{
+	vdev_t vtmp;
+	vdev_phys_t *vdev_label = (vdev_phys_t *) zap_scratch;
+	spa_t *spa;
+	vdev_t *vdev, *top_vdev, *pool_vdev;
+	off_t off;
+	blkptr_t bp;
+	const unsigned char *nvlist;
+	uint64_t val;
+	uint64_t guid;
+	uint64_t pool_txg, pool_guid;
+	const char *pool_name;
+	const unsigned char *vdevs;
+	int i;
+	char upbuf[1024];
+	const struct uberblock *up;
+
+	/*
+	 * Load the vdev label and figure out which
+	 * uberblock is most current.
+	 */
+	memset(&vtmp, 0, sizeof(vtmp));
+	vtmp.v_read = read;
+	vtmp.v_read_priv = read_priv;
+	off = offsetof(vdev_label_t, vl_vdev_phys);
+	BP_ZERO(&bp);
+	BP_SET_LSIZE(&bp, sizeof(vdev_phys_t));
+	BP_SET_PSIZE(&bp, sizeof(vdev_phys_t));
+	BP_SET_CHECKSUM(&bp, ZIO_CHECKSUM_LABEL);
+	BP_SET_COMPRESS(&bp, ZIO_COMPRESS_OFF);
+	ZIO_SET_CHECKSUM(&bp.blk_cksum, off, 0, 0, 0);
+	if (zio_read_phys(&vtmp, &bp, vdev_label, off))
+		return (EIO);
+
+	if (vdev_label->vp_nvlist[0] != NV_ENCODE_XDR) {
+		return (EIO);
+	}
+
+	nvlist = (const unsigned char *) vdev_label->vp_nvlist + 4;
+
+	if (nvlist_find(nvlist,
+			ZPOOL_CONFIG_VERSION,
+			DATA_TYPE_UINT64, 0, &val)) {
+		return (EIO);
+	}
+
+	if (val != ZFS_VERSION) {
+		printf("ZFS: unsupported ZFS version %d\n", (int) val);
+		return (EIO);
+	}
+
+	if (nvlist_find(nvlist,
+			ZPOOL_CONFIG_POOL_STATE,
+			DATA_TYPE_UINT64, 0, &val)) {
+		return (EIO);
+	}
+
+	if (val != POOL_STATE_ACTIVE) {
+		/*
+		 * Don't print a message here. If we happen to reboot
+		 * while where is an exported pool around, we don't
+		 * need a cascade of confusing messages during boot.
+		 */
+		/*printf("ZFS: pool is not active\n");*/
+		return (EIO);
+	}
+
+	if (nvlist_find(nvlist,
+			ZPOOL_CONFIG_POOL_TXG,
+			DATA_TYPE_UINT64, 0, &pool_txg)
+	    || nvlist_find(nvlist,
+			   ZPOOL_CONFIG_POOL_GUID,
+			   DATA_TYPE_UINT64, 0, &pool_guid)
+	    || nvlist_find(nvlist,
+			   ZPOOL_CONFIG_POOL_NAME,
+			   DATA_TYPE_STRING, 0, &pool_name)) {
+		printf("ZFS: can't find pool details\n");
+		return (EIO);
+	}
+
+	/*
+	 * Create the pool if this is the first time we've seen it.
+	 */
+	spa = spa_find_by_guid(pool_guid);
+	if (!spa) {
+		spa = spa_create(pool_guid);
+		spa->spa_name = strdup(pool_name);
+	}
+	if (pool_txg > spa->spa_txg)
+		spa->spa_txg = pool_txg;
+
+	/*
+	 * Get the vdev tree and create our in-core copy of it.
+	 * If we already have a healthy vdev with this guid, this must
+	 * be some kind of alias (overlapping slices, dangerously dedicated
+	 * disks etc).
+	 */
+	if (nvlist_find(nvlist,
+			ZPOOL_CONFIG_GUID,
+			DATA_TYPE_UINT64, 0, &guid)) {
+		return (EIO);
+	}
+	vdev = vdev_find(guid);
+	if (vdev && vdev->v_state == VDEV_STATE_HEALTHY) {
+		return (EIO);
+	}
+
+	if (nvlist_find(nvlist,
+			ZPOOL_CONFIG_VDEV_TREE,
+			DATA_TYPE_NVLIST, 0, &vdevs)) {
+		return (EIO);
+	}
+	vdev_init_from_nvlist(vdevs, &top_vdev);
+
+	/*
+	 * Add the toplevel vdev to the pool if its not already there.
+	 */
+	STAILQ_FOREACH(pool_vdev, &spa->spa_vdevs, v_childlink)
+		if (top_vdev == pool_vdev)
+			break;
+	if (!pool_vdev && top_vdev)
+		STAILQ_INSERT_TAIL(&spa->spa_vdevs, top_vdev, v_childlink);
+
+	/*
+	 * We should already have created an incomplete vdev for this
+	 * vdev. Find it and initialise it with our read proc.
+	 */
+	vdev = vdev_find(guid);
+	if (vdev) {
+		vdev->v_read = read;
+		vdev->v_read_priv = read_priv;
+		vdev->v_state = VDEV_STATE_HEALTHY;
+	} else {
+		printf("ZFS: inconsistent nvlist contents\n");
+		return (EIO);
+	}
+
+	/*
+	 * Re-evaluate top-level vdev state.
+	 */
+	vdev_set_state(top_vdev);
+
+	/*
+	 * Ok, we are happy with the pool so far. Lets find
+	 * the best uberblock and then we can actually access
+	 * the contents of the pool.
+	 */
+	for (i = 0;
+	     i < VDEV_UBERBLOCK_RING >> UBERBLOCK_SHIFT;
+	     i++) {
+		off = offsetof(vdev_label_t, vl_uberblock);
+		off += i << UBERBLOCK_SHIFT;
+		BP_ZERO(&bp);
+		DVA_SET_OFFSET(&bp.blk_dva[0], off);
+		BP_SET_LSIZE(&bp, 1 << UBERBLOCK_SHIFT);
+		BP_SET_PSIZE(&bp, 1 << UBERBLOCK_SHIFT);
+		BP_SET_CHECKSUM(&bp, ZIO_CHECKSUM_LABEL);
+		BP_SET_COMPRESS(&bp, ZIO_COMPRESS_OFF);
+		ZIO_SET_CHECKSUM(&bp.blk_cksum, off, 0, 0, 0);
+		if (zio_read_phys(vdev, &bp, upbuf, off))
+			continue;
+
+		up = (const struct uberblock *) upbuf;
+		if (up->ub_magic != UBERBLOCK_MAGIC)
+			continue;
+		if (up->ub_txg < spa->spa_txg)
+			continue;
+		if (up->ub_txg > spa->spa_uberblock.ub_txg) {
+			spa->spa_uberblock = *up;
+		} else if (up->ub_txg == spa->spa_uberblock.ub_txg) {
+			if (up->ub_timestamp > spa->spa_uberblock.ub_timestamp)
+				spa->spa_uberblock = *up;
+		}
+	}
+
+	if (spap)
+		*spap = spa;
+	return (0);
+}
+
+static int
+ilog2(int n)
+{
+	int v;
+
+	for (v = 0; v < 32; v++)
+		if (n == (1 << v))
+			return v;
+	return -1;
+}
+
+static int
+zio_read_phys(vdev_t *vdev, const blkptr_t *bp, void *buf, off_t offset)
+{
+	int cpfunc = BP_GET_COMPRESS(bp);
+	size_t lsize = BP_GET_LSIZE(bp);
+	size_t psize = BP_GET_PSIZE(bp);
+	int rc;
+
+	/*printf("ZFS: reading %d bytes at 0x%llx to %p\n", psize, offset, buf);*/
+	if (cpfunc != ZIO_COMPRESS_OFF) {
+		rc = vdev->v_read(vdev, vdev->v_read_priv, offset, zfs_decomp_buf, psize);
+		if (rc)
+			return (rc);
+		if (zio_checksum_error(bp, zfs_decomp_buf))
+			return (EIO);
+		if (zio_decompress_data(cpfunc, zfs_decomp_buf, psize,
+			buf, lsize))
+			return (EIO);
+	} else {
+		rc = vdev->v_read(vdev, vdev->v_read_priv, offset, buf, psize);
+		if (rc)
+			return (rc);
+					  
+		if (zio_checksum_error(bp, buf))
+			return (EIO);
+	}
+	return (0);
+}
+
+static int
+zio_read(spa_t *spa, const blkptr_t *bp, void *buf)
+{
+	int i;
+
+	for (i = 0; i < SPA_DVAS_PER_BP; i++) {
+		const dva_t *dva = &bp->blk_dva[i];
+		vdev_t *vdev;
+		int vdevid;
+		off_t offset;
+
+		if (!dva->dva_word[0] && !dva->dva_word[1])
+			continue;
+
+		vdevid = DVA_GET_VDEV(dva);
+		offset = DVA_GET_OFFSET(dva) + VDEV_LABEL_START_SIZE;
+		STAILQ_FOREACH(vdev, &spa->spa_vdevs, v_childlink)
+			if (vdev->v_id == vdevid)
+				break;
+		if (!vdev || !vdev->v_read)
+			continue;
+		if (zio_read_phys(vdev, bp, buf, offset))
+			continue;
+
+		return (0);
+	}
+	printf("ZFS: i/o error - all block copies unavailable\n");
+
+	return (EIO);
+}
+
+static int
+dnode_read(spa_t *spa, const dnode_phys_t *dnode, off_t offset, void *buf, size_t buflen)
+{
+	int ibshift = dnode->dn_indblkshift - SPA_BLKPTRSHIFT;
+	int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
+	int nlevels = dnode->dn_nlevels;
+	int i, rc;
+
+	/*
+	 * We truncate the offset to 32bits, mainly so that I don't
+	 * have to find a copy of __divdi3 to put into the bootstrap.
+	 * I don't think the bootstrap needs to access anything bigger
+	 * than 2G anyway. Note that block addresses are still 64bit
+	 * so it doesn't affect the possible size of the media.
+	 * We still use 64bit block numbers so that the bitshifts
+	 * work correctly. Note: bsize may not be a power of two here.
+	 */
+	while (buflen > 0) {
+		uint64_t bn = ((int) offset) / bsize;
+		int boff = ((int) offset) % bsize;
+		int ibn;
+		const blkptr_t *indbp;
+		blkptr_t bp;
+
+		if (bn > dnode->dn_maxblkid)
+			return (EIO);
+
+		if (dnode == dnode_cache_obj && bn == dnode_cache_bn)
+			goto cached;
+
+		indbp = dnode->dn_blkptr;
+		for (i = 0; i < nlevels; i++) {
+			/*
+			 * Copy the bp from the indirect array so that
+			 * we can re-use the scratch buffer for multi-level
+			 * objects.
+			 */
+			ibn = bn >> ((nlevels - i - 1) * ibshift);
+			ibn &= ((1 << ibshift) - 1);
+			bp = indbp[ibn];
+			rc = zio_read(spa, &bp, dnode_cache_buf);
+			if (rc)
+				return (rc);
+			indbp = (const blkptr_t *) dnode_cache_buf;
+		}
+		dnode_cache_obj = dnode;
+		dnode_cache_bn = bn;
+	cached:
+
+		/*
+		 * The buffer contains our data block. Copy what we
+		 * need from it and loop.
+		 */ 
+		i = bsize - boff;
+		if (i > buflen) i = buflen;
+		memcpy(buf, &dnode_cache_buf[boff], i);
+		buf = ((char*) buf) + i;
+		offset += i;
+		buflen -= i;
+	}
+
+	return (0);
+}
+
+/*
+ * Lookup a value in a microzap directory. Assumes that the zap
+ * scratch buffer contains the directory contents.
+ */
+static int
+mzap_lookup(spa_t *spa, const dnode_phys_t *dnode, const char *name, uint64_t *value)
+{
+	const mzap_phys_t *mz;
+	const mzap_ent_phys_t *mze;
+	size_t size;
+	int chunks, i;
+
+	/*
+	 * Microzap objects use exactly one block. Read the whole
+	 * thing.
+	 */
+	size = dnode->dn_datablkszsec * 512;
+
+	mz = (const mzap_phys_t *) zap_scratch;
+	chunks = size / MZAP_ENT_LEN - 1;
+
+	for (i = 0; i < chunks; i++) {
+		mze = &mz->mz_chunk[i];
+		if (!strcmp(mze->mze_name, name)) {
+			*value = mze->mze_value;
+			return (0);
+		}
+	}
+
+	return (ENOENT);
+}
+
+/*
+ * Compare a name with a zap leaf entry. Return non-zero if the name
+ * matches.
+ */
+static int
+fzap_name_equal(const zap_leaf_t *zl, const zap_leaf_chunk_t *zc, const char *name)
+{
+	size_t namelen;
+	const zap_leaf_chunk_t *nc;
+	const char *p;
+
+	namelen = zc->l_entry.le_name_length;
+			
+	nc = &ZAP_LEAF_CHUNK(zl, zc->l_entry.le_name_chunk);
+	p = name;
+	while (namelen > 0) {
+		size_t len;
+		len = namelen;
+		if (len > ZAP_LEAF_ARRAY_BYTES)
+			len = ZAP_LEAF_ARRAY_BYTES;
+		if (memcmp(p, nc->l_array.la_array, len))
+			return (0);
+		p += len;
+		namelen -= len;
+		nc = &ZAP_LEAF_CHUNK(zl, nc->l_array.la_next);
+	}
+
+	return 1;
+}
+
+/*
+ * Extract a uint64_t value from a zap leaf entry.
+ */
+static uint64_t
+fzap_leaf_value(const zap_leaf_t *zl, const zap_leaf_chunk_t *zc)
+{
+	const zap_leaf_chunk_t *vc;
+	int i;
+	uint64_t value;
+	const uint8_t *p;
+
+	vc = &ZAP_LEAF_CHUNK(zl, zc->l_entry.le_value_chunk);
+	for (i = 0, value = 0, p = vc->l_array.la_array; i < 8; i++) {
+		value = (value << 8) | p[i];
+	}
+
+	return value;
+}
+
+/*
+ * Lookup a value in a fatzap directory. Assumes that the zap scratch
+ * buffer contains the directory header.
+ */
+static int
+fzap_lookup(spa_t *spa, const dnode_phys_t *dnode, const char *name, uint64_t *value)
+{
+	int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
+	zap_phys_t zh = *(zap_phys_t *) zap_scratch;
+	fat_zap_t z;
+	uint64_t *ptrtbl;
+	uint64_t hash;
+	int rc;
+
+	if (zh.zap_magic != ZAP_MAGIC)
+		return (EIO);
+
+	z.zap_block_shift = ilog2(bsize);
+	z.zap_phys = (zap_phys_t *) zap_scratch;
+
+	/*
+	 * Figure out where the pointer table is and read it in if necessary.
+	 */
+	if (zh.zap_ptrtbl.zt_blk) {
+		rc = dnode_read(spa, dnode, zh.zap_ptrtbl.zt_blk * bsize,
+			       zap_scratch, bsize);
+		if (rc)
+			return (rc);
+		ptrtbl = (uint64_t *) zap_scratch;
+	} else {
+		ptrtbl = &ZAP_EMBEDDED_PTRTBL_ENT(&z, 0);
+	}
+
+	hash = zap_hash(zh.zap_salt, name);
+
+	zap_leaf_t zl;
+	zl.l_bs = z.zap_block_shift;
+
+	off_t off = ptrtbl[hash >> (64 - zh.zap_ptrtbl.zt_shift)] << zl.l_bs;
+	zap_leaf_chunk_t *zc;
+
+	rc = dnode_read(spa, dnode, off, zap_scratch, bsize);
+	if (rc)
+		return (rc);
+
+	zl.l_phys = (zap_leaf_phys_t *) zap_scratch;
+
+	/*
+	 * Make sure this chunk matches our hash.
+	 */
+	if (zl.l_phys->l_hdr.lh_prefix_len > 0
+	    && zl.l_phys->l_hdr.lh_prefix
+	    != hash >> (64 - zl.l_phys->l_hdr.lh_prefix_len))
+		return (ENOENT);
+
+	/*
+	 * Hash within the chunk to find our entry.
+	 */
+	int shift = (64 - ZAP_LEAF_HASH_SHIFT(&zl) - zl.l_phys->l_hdr.lh_prefix_len);
+	int h = (hash >> shift) & ((1 << ZAP_LEAF_HASH_SHIFT(&zl)) - 1);
+	h = zl.l_phys->l_hash[h];
+	if (h == 0xffff)
+		return (ENOENT);
+	zc = &ZAP_LEAF_CHUNK(&zl, h);
+	while (zc->l_entry.le_hash != hash) {
+		if (zc->l_entry.le_next == 0xffff) {
+			zc = 0;
+			break;
+		}
+		zc = &ZAP_LEAF_CHUNK(&zl, zc->l_entry.le_next);
+	}
+	if (fzap_name_equal(&zl, zc, name)) {
+		*value = fzap_leaf_value(&zl, zc);
+		return (0);
+	}
+
+	return (ENOENT);
+}
+
+/*
+ * Lookup a name in a zap object and return its value as a uint64_t.
+ */
+static int
+zap_lookup(spa_t *spa, const dnode_phys_t *dnode, const char *name, uint64_t *value)
+{
+	int rc;
+	uint64_t zap_type;
+	size_t size = dnode->dn_datablkszsec * 512;
+
+	rc = dnode_read(spa, dnode, 0, zap_scratch, size);
+	if (rc)
+		return (rc);
+
+	zap_type = *(uint64_t *) zap_scratch;
+	if (zap_type == ZBT_MICRO)
+		return mzap_lookup(spa, dnode, name, value);
+	else
+		return fzap_lookup(spa, dnode, name, value);
+}
+
+#ifdef BOOT2
+
+/*
+ * List a microzap directory. Assumes that the zap scratch buffer contains
+ * the directory contents.
+ */
+static int
+mzap_list(spa_t *spa, const dnode_phys_t *dnode)
+{
+	const mzap_phys_t *mz;
+	const mzap_ent_phys_t *mze;
+	size_t size;
+	int chunks, i;
+
+	/*
+	 * Microzap objects use exactly one block. Read the whole
+	 * thing.
+	 */
+	size = dnode->dn_datablkszsec * 512;
+	mz = (const mzap_phys_t *) zap_scratch;
+	chunks = size / MZAP_ENT_LEN - 1;
+
+	for (i = 0; i < chunks; i++) {
+		mze = &mz->mz_chunk[i];
+		if (mze->mze_name[0])
+			//printf("%-32s 0x%llx\n", mze->mze_name, mze->mze_value);
+			printf("%s\n", mze->mze_name);
+	}
+
+	return (0);
+}
+
+/*
+ * List a fatzap directory. Assumes that the zap scratch buffer contains
+ * the directory header.
+ */
+static int
+fzap_list(spa_t *spa, const dnode_phys_t *dnode)
+{
+	int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
+	zap_phys_t zh = *(zap_phys_t *) zap_scratch;
+	fat_zap_t z;
+	int i, j;
+
+	if (zh.zap_magic != ZAP_MAGIC)
+		return (EIO);
+
+	z.zap_block_shift = ilog2(bsize);
+	z.zap_phys = (zap_phys_t *) zap_scratch;
+
+	/*
+	 * This assumes that the leaf blocks start at block 1. The
+	 * documentation isn't exactly clear on this.
+	 */
+	zap_leaf_t zl;
+	zl.l_bs = z.zap_block_shift;
+	for (i = 0; i < zh.zap_num_leafs; i++) {
+		off_t off = (i + 1) << zl.l_bs;
+		char name[256], *p;
+		uint64_t value;
+
+		if (dnode_read(spa, dnode, off, zap_scratch, bsize))
+			return (EIO);
+
+		zl.l_phys = (zap_leaf_phys_t *) zap_scratch;
+
+		for (j = 0; j < ZAP_LEAF_NUMCHUNKS(&zl); j++) {
+			zap_leaf_chunk_t *zc, *nc;
+			int namelen;
+
+			zc = &ZAP_LEAF_CHUNK(&zl, j);
+			if (zc->l_entry.le_type != ZAP_CHUNK_ENTRY)
+				continue;
+			namelen = zc->l_entry.le_name_length;
+			if (namelen > sizeof(name))
+				namelen = sizeof(name);
+			
+			/*
+			 * Paste the name back together.
+			 */
+			nc = &ZAP_LEAF_CHUNK(&zl, zc->l_entry.le_name_chunk);
+			p = name;
+			while (namelen > 0) {
+				int len;
+				len = namelen;
+				if (len > ZAP_LEAF_ARRAY_BYTES)
+					len = ZAP_LEAF_ARRAY_BYTES;
+				memcpy(p, nc->l_array.la_array, len);
+				p += len;
+				namelen -= len;
+				nc = &ZAP_LEAF_CHUNK(&zl, nc->l_array.la_next);
+			}
+
+			/*
+			 * Assume the first eight bytes of the value are
+			 * a uint64_t.
+			 */
+			value = fzap_leaf_value(&zl, zc);
+
+			printf("%-32s 0x%llx\n", name, value);
+		}
+	}
+
+	return (0);
+}
+
+/*
+ * List a zap directory.
+ */
+static int
+zap_list(spa_t *spa, const dnode_phys_t *dnode)
+{
+	uint64_t zap_type;
+	size_t size = dnode->dn_datablkszsec * 512;
+
+	if (dnode_read(spa, dnode, 0, zap_scratch, size))
+		return (EIO);
+
+	zap_type = *(uint64_t *) zap_scratch;
+	if (zap_type == ZBT_MICRO)
+		return mzap_list(spa, dnode);
+	else
+		return fzap_list(spa, dnode);
+}
+
+#endif
+
+static int
+objset_get_dnode(spa_t *spa, const objset_phys_t *os, uint64_t objnum, dnode_phys_t *dnode)
+{
+	off_t offset;
+
+	offset = objnum * sizeof(dnode_phys_t);
+	return dnode_read(spa, &os->os_meta_dnode, offset,
+		dnode, sizeof(dnode_phys_t));
+}
+
+/*
+ * Find the object set given the object number of its dataset object
+ * and return its details in *objset
+ */
+static int
+zfs_mount_dataset(spa_t *spa, uint64_t objnum, objset_phys_t *objset)
+{
+	dnode_phys_t dataset;
+	dsl_dataset_phys_t *ds;
+
+	if (objset_get_dnode(spa, &spa->spa_mos, objnum, &dataset)) {
+		printf("ZFS: can't find dataset %lld\n", objnum);
+		return (EIO);
+	}
+
+	ds = (dsl_dataset_phys_t *) &dataset.dn_bonus;
+	if (zio_read(spa, &ds->ds_bp, objset)) {
+		printf("ZFS: can't read object set for dataset %lld\n", objnum);
+		return (EIO);
+	}
+
+	return (0);
+}
+
+/*
+ * Find the object set pointed to by the BOOTFS property or the root
+ * dataset if there is none and return its details in *objset
+ */
+static int
+zfs_mount_root(spa_t *spa, objset_phys_t *objset)
+{
+	dnode_phys_t dir, propdir;
+	uint64_t props, bootfs, root;
+
+	/*
+	 * Start with the MOS directory object.
+	 */
+	if (objset_get_dnode(spa, &spa->spa_mos, DMU_POOL_DIRECTORY_OBJECT, &dir)) {
+		printf("ZFS: can't read MOS object directory\n");
+		return (EIO);
+	}
+
+	/*
+	 * Lookup the pool_props and see if we can find a bootfs.
+	 */
+	if (zap_lookup(spa, &dir, DMU_POOL_PROPS, &props) == 0
+	     && objset_get_dnode(spa, &spa->spa_mos, props, &propdir) == 0
+	     && zap_lookup(spa, &propdir, "bootfs", &bootfs) == 0)
+		return zfs_mount_dataset(spa, bootfs, objset);
+
+	/*
+	 * Lookup the root dataset directory
+	 */
+	if (zap_lookup(spa, &dir, DMU_POOL_ROOT_DATASET, &root)
+	    || objset_get_dnode(spa, &spa->spa_mos, root, &dir)) {
+		printf("ZFS: can't find root dsl_dir\n");
+		return (EIO);
+	}
+
+	/*
+	 * Use the information from the dataset directory's bonus buffer
+	 * to find the dataset object and from that the object set itself.
+	 */
+	dsl_dir_phys_t *dd = (dsl_dir_phys_t *) &dir.dn_bonus;
+	return zfs_mount_dataset(spa, dd->dd_head_dataset_obj, objset);
+}
+
+static int
+zfs_mount_pool(spa_t *spa)
+{
+	/*
+	 * Find the MOS and work our way in from there.
+	 */
+	if (zio_read(spa, &spa->spa_uberblock.ub_rootbp, &spa->spa_mos)) {
+		printf("ZFS: can't read MOS\n");
+		return (EIO);
+	}
+
+	/*
+	 * Find the root object set
+	 */
+	if (zfs_mount_root(spa, &spa->spa_root_objset)) {
+		printf("Can't find root filesystem - giving up\n");
+		return (EIO);
+	}
+
+	return (0);
+}
+
+/*
+ * Lookup a file and return its dnode.
+ */
+static int
+zfs_lookup(spa_t *spa, const char *upath, dnode_phys_t *dnode)
+{
+	int rc;
+	uint64_t objnum, rootnum, parentnum;
+	dnode_phys_t dn;
+	const znode_phys_t *zp = (const znode_phys_t *) dn.dn_bonus;
+	const char *p, *q;
+	char element[256];
+	char path[1024];
+	int symlinks_followed = 0;
+
+	if (spa->spa_root_objset.os_type != DMU_OST_ZFS) {
+		printf("ZFS: unexpected object set type %lld\n",
+		       spa->spa_root_objset.os_type);
+		return (EIO);
+	}
+
+	/*
+	 * Get the root directory dnode.
+	 */
+	rc = objset_get_dnode(spa, &spa->spa_root_objset, MASTER_NODE_OBJ, &dn);
+	if (rc)
+		return (rc);
+
+	rc = zap_lookup(spa, &dn, ZFS_ROOT_OBJ, &rootnum);
+	if (rc)
+		return (rc);
+
+	rc = objset_get_dnode(spa, &spa->spa_root_objset, rootnum, &dn);
+	if (rc)
+		return (rc);
+
+	objnum = rootnum;
+	p = upath;
+	while (p && *p) {
+		while (*p == '/')
+			p++;
+		if (!*p)
+			break;
+		q = strchr(p, '/');
+		if (q) {
+			memcpy(element, p, q - p);
+			element[q - p] = 0;
+			p = q;
+		} else {
+			strcpy(element, p);
+			p = 0;
+		}
+
+		if ((zp->zp_mode >> 12) != 0x4) {
+			return (ENOTDIR);
+		}
+
+		parentnum = objnum;
+		rc = zap_lookup(spa, &dn, element, &objnum);
+		if (rc)
+			return (rc);
+		objnum = ZFS_DIRENT_OBJ(objnum);
+
+		rc = objset_get_dnode(spa, &spa->spa_root_objset, objnum, &dn);
+		if (rc)
+			return (rc);
+
+		/*
+		 * Check for symlink.
+		 */
+		if ((zp->zp_mode >> 12) == 0xa) {
+			if (symlinks_followed > 10)
+				return (EMLINK);
+			symlinks_followed++;
+
+			/*
+			 * Read the link value and copy the tail of our
+			 * current path onto the end.
+			 */
+			if (p)
+				strcpy(&path[zp->zp_size], p);
+			else
+				path[zp->zp_size] = 0;
+			if (zp->zp_size + sizeof(znode_phys_t) <= dn.dn_bonuslen) {
+				memcpy(path, &dn.dn_bonus[sizeof(znode_phys_t)],
+					zp->zp_size);
+			} else {
+				rc = dnode_read(spa, &dn, 0, path, zp->zp_size);
+				if (rc)
+					return (rc);
+			}
+
+			/*
+			 * Restart with the new path, starting either at
+			 * the root or at the parent depending whether or
+			 * not the link is relative.
+			 */
+			p = path;
+			if (*p == '/')
+				objnum = rootnum;
+			else
+				objnum = parentnum;
+			objset_get_dnode(spa, &spa->spa_root_objset, objnum, &dn);
+		}
+	}
+
+	*dnode = dn;
+	return (0);
+}