zfs: Add ZFS filesystem support

U-Boot port is based on sources forked from GRUB-0.97 by Sun in 2004,
which can be found here:
http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/grub/grub-0.97/stage2/zfs-include/zfs.h

Released by Sun for GRUB under the license:
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2 of the License, or
  *  (at your option) any later version.

GRUB official releases include ZFS in version:
ftp://alpha.gnu.org/gnu/grub/grub-1.99~rc1.tar.gz

And patched against GRUB Bazaar repository for ashift fixes (4KB HDDs)
more conveniently found at github:
https://github.com/pendor/grub-zfs/commit/e7b6ef3ac3b9685ac4c394c897b1d4221b7381f1

Signed-off-by: Jorgen Lundman <lundman@lundman.net>

1 files changed, 2395 insertions, 0 deletions

diff --git a/fs/zfs/zfs.c b/fs/zfs/zfs.c
new file mode 100644
index 0000000..360f723
--- /dev/null
+++ b/fs/zfs/zfs.c
@@ -0,0 +1,2395 @@
+/*
+ *
+ * ZFS filesystem ported to u-boot by
+ * Jorgen Lundman <lundman at lundman.net>
+ *
+ *	GRUB  --  GRand Unified Bootloader
+ *	Copyright (C) 1999,2000,2001,2002,2003,2004
+ *	Free Software Foundation, Inc.
+ *	Copyright 2004	Sun Microsystems, Inc.
+ *
+ *	GRUB is free software; you can redistribute it and/or modify
+ *	it under the terms of the GNU General Public License as published by
+ *	the Free Software Foundation; either version 2 of the License, or
+ *	(at your option) any later version.
+ *
+ *	GRUB is distributed in the hope that it will be useful,
+ *	but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *	GNU General Public License for more details.
+ *
+ *	You should have received a copy of the GNU General Public License
+ *	along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <common.h>
+#include <malloc.h>
+#include <linux/stat.h>
+#include <linux/time.h>
+#include <linux/ctype.h>
+#include <asm/byteorder.h>
+#include "zfs_common.h"
+
+block_dev_desc_t *zfs_dev_desc;
+
+/*
+ * The zfs plug-in routines for GRUB are:
+ *
+ * zfs_mount() - locates a valid uberblock of the root pool and reads
+ *		in its MOS at the memory address MOS.
+ *
+ * zfs_open() - locates a plain file object by following the MOS
+ *		and places its dnode at the memory address DNODE.
+ *
+ * zfs_read() - read in the data blocks pointed by the DNODE.
+ *
+ */
+
+#include <zfs/zfs.h>
+#include <zfs/zio.h>
+#include <zfs/dnode.h>
+#include <zfs/uberblock_impl.h>
+#include <zfs/vdev_impl.h>
+#include <zfs/zio_checksum.h>
+#include <zfs/zap_impl.h>
+#include <zfs/zap_leaf.h>
+#include <zfs/zfs_znode.h>
+#include <zfs/dmu.h>
+#include <zfs/dmu_objset.h>
+#include <zfs/sa_impl.h>
+#include <zfs/dsl_dir.h>
+#include <zfs/dsl_dataset.h>
+
+
+#define	ZPOOL_PROP_BOOTFS		"bootfs"
+
+
+/*
+ * For nvlist manipulation. (from nvpair.h)
+ */
+#define	NV_ENCODE_NATIVE	0
+#define	NV_ENCODE_XDR		1
+#define	NV_BIG_ENDIAN			0
+#define	NV_LITTLE_ENDIAN	1
+#define	DATA_TYPE_UINT64	8
+#define	DATA_TYPE_STRING	9
+#define	DATA_TYPE_NVLIST	19
+#define	DATA_TYPE_NVLIST_ARRAY	20
+
+
+/*
+ * Macros to get fields in a bp or DVA.
+ */
+#define	P2PHASE(x, align)		((x) & ((align) - 1))
+#define	DVA_OFFSET_TO_PHYS_SECTOR(offset)					\
+	((offset + VDEV_LABEL_START_SIZE) >> SPA_MINBLOCKSHIFT)
+
+/*
+ * return x rounded down to an align boundary
+ * eg, P2ALIGN(1200, 1024) == 1024 (1*align)
+ * eg, P2ALIGN(1024, 1024) == 1024 (1*align)
+ * eg, P2ALIGN(0x1234, 0x100) == 0x1200 (0x12*align)
+ * eg, P2ALIGN(0x5600, 0x100) == 0x5600 (0x56*align)
+ */
+#define	P2ALIGN(x, align)		((x) & -(align))
+
+/*
+ * FAT ZAP data structures
+ */
+#define	ZFS_CRC64_POLY 0xC96C5795D7870F42ULL	/* ECMA-182, reflected form */
+#define	ZAP_HASH_IDX(hash, n)	(((n) == 0) ? 0 : ((hash) >> (64 - (n))))
+#define	CHAIN_END	0xffff	/* end of the chunk chain */
+
+/*
+ * The amount of space within the chunk available for the array is:
+ * chunk size - space for type (1) - space for next pointer (2)
+ */
+#define	ZAP_LEAF_ARRAY_BYTES (ZAP_LEAF_CHUNKSIZE - 3)
+
+#define	ZAP_LEAF_HASH_SHIFT(bs)	(bs - 5)
+#define	ZAP_LEAF_HASH_NUMENTRIES(bs) (1 << ZAP_LEAF_HASH_SHIFT(bs))
+#define	LEAF_HASH(bs, h)												\
+	((ZAP_LEAF_HASH_NUMENTRIES(bs)-1) &									\
+	 ((h) >> (64 - ZAP_LEAF_HASH_SHIFT(bs)-l->l_hdr.lh_prefix_len)))
+
+/*
+ * The amount of space available for chunks is:
+ * block size shift - hash entry size (2) * number of hash
+ * entries - header space (2*chunksize)
+ */
+#define	ZAP_LEAF_NUMCHUNKS(bs)						\
+	(((1<<bs) - 2*ZAP_LEAF_HASH_NUMENTRIES(bs)) /	\
+	 ZAP_LEAF_CHUNKSIZE - 2)
+
+/*
+ * The chunks start immediately after the hash table.  The end of the
+ * hash table is at l_hash + HASH_NUMENTRIES, which we simply cast to a
+ * chunk_t.
+ */
+#define	ZAP_LEAF_CHUNK(l, bs, idx)										\
+	((zap_leaf_chunk_t *)(l->l_hash + ZAP_LEAF_HASH_NUMENTRIES(bs)))[idx]
+#define	ZAP_LEAF_ENTRY(l, bs, idx) (&ZAP_LEAF_CHUNK(l, bs, idx).l_entry)
+
+
+/*
+ * Decompression Entry - lzjb
+ */
+#ifndef	NBBY
+#define	NBBY	8
+#endif
+
+
+
+typedef int zfs_decomp_func_t(void *s_start, void *d_start,
+							  uint32_t s_len, uint32_t d_len);
+typedef struct decomp_entry {
+	char *name;
+	zfs_decomp_func_t *decomp_func;
+} decomp_entry_t;
+
+typedef struct dnode_end {
+	dnode_phys_t dn;
+	zfs_endian_t endian;
+} dnode_end_t;
+
+struct zfs_data {
+	/* cache for a file block of the currently zfs_open()-ed file */
+	char *file_buf;
+	uint64_t file_start;
+	uint64_t file_end;
+
+	/* XXX: ashift is per vdev, not per pool.  We currently only ever touch
+	 * a single vdev, but when/if raid-z or stripes are supported, this
+	 * may need revision.
+	 */
+	uint64_t vdev_ashift;
+	uint64_t label_txg;
+	uint64_t pool_guid;
+
+	/* cache for a dnode block */
+	dnode_phys_t *dnode_buf;
+	dnode_phys_t *dnode_mdn;
+	uint64_t dnode_start;
+	uint64_t dnode_end;
+	zfs_endian_t dnode_endian;
+
+	uberblock_t current_uberblock;
+
+	dnode_end_t mos;
+	dnode_end_t mdn;
+	dnode_end_t dnode;
+
+	uint64_t vdev_phys_sector;
+
+	int (*userhook)(const char *, const struct zfs_dirhook_info *);
+	struct zfs_dirhook_info *dirinfo;
+
+};
+
+
+
+
+static int
+zlib_decompress(void *s, void *d,
+				uint32_t slen, uint32_t dlen)
+{
+	if (zlib_decompress(s, d, slen, dlen) < 0)
+		return ZFS_ERR_BAD_FS;
+	return ZFS_ERR_NONE;
+}
+
+static decomp_entry_t decomp_table[ZIO_COMPRESS_FUNCTIONS] = {
+	{"inherit", NULL},		/* ZIO_COMPRESS_INHERIT */
+	{"on", lzjb_decompress},	/* ZIO_COMPRESS_ON */
+	{"off", NULL},		/* ZIO_COMPRESS_OFF */
+	{"lzjb", lzjb_decompress},	/* ZIO_COMPRESS_LZJB */
+	{"empty", NULL},		/* ZIO_COMPRESS_EMPTY */
+	{"gzip-1", zlib_decompress},  /* ZIO_COMPRESS_GZIP1 */
+	{"gzip-2", zlib_decompress},  /* ZIO_COMPRESS_GZIP2 */
+	{"gzip-3", zlib_decompress},  /* ZIO_COMPRESS_GZIP3 */
+	{"gzip-4", zlib_decompress},  /* ZIO_COMPRESS_GZIP4 */
+	{"gzip-5", zlib_decompress},  /* ZIO_COMPRESS_GZIP5 */
+	{"gzip-6", zlib_decompress},  /* ZIO_COMPRESS_GZIP6 */
+	{"gzip-7", zlib_decompress},  /* ZIO_COMPRESS_GZIP7 */
+	{"gzip-8", zlib_decompress},  /* ZIO_COMPRESS_GZIP8 */
+	{"gzip-9", zlib_decompress},  /* ZIO_COMPRESS_GZIP9 */
+};
+
+
+
+static int zio_read_data(blkptr_t *bp, zfs_endian_t endian,
+						 void *buf, struct zfs_data *data);
+
+static int
+zio_read(blkptr_t *bp, zfs_endian_t endian, void **buf,
+		 size_t *size, struct zfs_data *data);
+
+/*
+ * Our own version of log2().  Same thing as highbit()-1.
+ */
+static int
+zfs_log2(uint64_t num)
+{
+	int i = 0;
+
+	while (num > 1) {
+		i++;
+		num = num >> 1;
+	}
+
+	return i;
+}
+
+
+/* Checksum Functions */
+static void
+zio_checksum_off(const void *buf __attribute__ ((unused)),
+				 uint64_t size __attribute__ ((unused)),
+				 zfs_endian_t endian __attribute__ ((unused)),
+				 zio_cksum_t *zcp)
+{
+	ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
+}
+
+/* Checksum Table and Values */
+static zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = {
+	{NULL, 0, 0, "inherit"},
+	{NULL, 0, 0, "on"},
+	{zio_checksum_off, 0, 0, "off"},
+	{zio_checksum_SHA256, 1, 1, "label"},
+	{zio_checksum_SHA256, 1, 1, "gang_header"},
+	{NULL, 0, 0, "zilog"},
+	{fletcher_2_endian, 0, 0, "fletcher2"},
+	{fletcher_4_endian, 1, 0, "fletcher4"},
+	{zio_checksum_SHA256, 1, 0, "SHA256"},
+	{NULL, 0, 0, "zilog2"},
+};
+
+/*
+ * zio_checksum_verify: Provides support for checksum verification.
+ *
+ * Fletcher2, Fletcher4, and SHA256 are supported.
+ *
+ */
+static int
+zio_checksum_verify(zio_cksum_t zc, uint32_t checksum,
+					zfs_endian_t endian, char *buf, int size)
+{
+	zio_eck_t *zec = (zio_eck_t *) (buf + size) - 1;
+	zio_checksum_info_t *ci = &zio_checksum_table[checksum];
+	zio_cksum_t actual_cksum, expected_cksum;
+
+	if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func == NULL) {
+		printf("zfs unknown checksum function %d\n", checksum);
+		return ZFS_ERR_NOT_IMPLEMENTED_YET;
+	}
+
+	if (ci->ci_eck) {
+		expected_cksum = zec->zec_cksum;
+		zec->zec_cksum = zc;
+		ci->ci_func(buf, size, endian, &actual_cksum);
+		zec->zec_cksum = expected_cksum;
+		zc = expected_cksum;
+	} else {
+		ci->ci_func(buf, size, endian, &actual_cksum);
+	}
+
+	if ((actual_cksum.zc_word[0] != zc.zc_word[0])
+		|| (actual_cksum.zc_word[1] != zc.zc_word[1])
+		|| (actual_cksum.zc_word[2] != zc.zc_word[2])
+		|| (actual_cksum.zc_word[3] != zc.zc_word[3])) {
+		return ZFS_ERR_BAD_FS;
+	}
+
+	return ZFS_ERR_NONE;
+}
+
+/*
+ * vdev_uberblock_compare takes two uberblock structures and returns an integer
+ * indicating the more recent of the two.
+ *	Return Value = 1 if ub2 is more recent
+ *	Return Value = -1 if ub1 is more recent
+ * The most recent uberblock is determined using its transaction number and
+ * timestamp.  The uberblock with the highest transaction number is
+ * considered "newer".	If the transaction numbers of the two blocks match, the
+ * timestamps are compared to determine the "newer" of the two.
+ */
+static int
+vdev_uberblock_compare(uberblock_t *ub1, uberblock_t *ub2)
+{
+	zfs_endian_t ub1_endian, ub2_endian;
+	if (zfs_to_cpu64(ub1->ub_magic, LITTLE_ENDIAN) == UBERBLOCK_MAGIC)
+		ub1_endian = LITTLE_ENDIAN;
+	else
+		ub1_endian = BIG_ENDIAN;
+	if (zfs_to_cpu64(ub2->ub_magic, LITTLE_ENDIAN) == UBERBLOCK_MAGIC)
+		ub2_endian = LITTLE_ENDIAN;
+	else
+		ub2_endian = BIG_ENDIAN;
+
+	if (zfs_to_cpu64(ub1->ub_txg, ub1_endian)
+		< zfs_to_cpu64(ub2->ub_txg, ub2_endian))
+		return -1;
+	if (zfs_to_cpu64(ub1->ub_txg, ub1_endian)
+		> zfs_to_cpu64(ub2->ub_txg, ub2_endian))
+		return 1;
+
+	if (zfs_to_cpu64(ub1->ub_timestamp, ub1_endian)
+		< zfs_to_cpu64(ub2->ub_timestamp, ub2_endian))
+		return -1;
+	if (zfs_to_cpu64(ub1->ub_timestamp, ub1_endian)
+		> zfs_to_cpu64(ub2->ub_timestamp, ub2_endian))
+		return 1;
+
+	return 0;
+}
+
+/*
+ * Three pieces of information are needed to verify an uberblock: the magic
+ * number, the version number, and the checksum.
+ *
+ * Currently Implemented: version number, magic number, label txg
+ * Need to Implement: checksum
+ *
+ */
+static int
+uberblock_verify(uberblock_t *uber, int offset, struct zfs_data *data)
+{
+	int err;
+	zfs_endian_t endian = UNKNOWN_ENDIAN;
+	zio_cksum_t zc;
+
+	if (uber->ub_txg < data->label_txg) {
+		debug("ignoring partially written label: uber_txg < label_txg %llu %llu\n",
+			  uber->ub_txg, data->label_txg);
+		return ZFS_ERR_BAD_FS;
+	}
+
+	if (zfs_to_cpu64(uber->ub_magic, LITTLE_ENDIAN) == UBERBLOCK_MAGIC
+		&& zfs_to_cpu64(uber->ub_version, LITTLE_ENDIAN) > 0
+		&& zfs_to_cpu64(uber->ub_version, LITTLE_ENDIAN) <= SPA_VERSION)
+		endian = LITTLE_ENDIAN;
+
+	if (zfs_to_cpu64(uber->ub_magic, BIG_ENDIAN) == UBERBLOCK_MAGIC
+		&& zfs_to_cpu64(uber->ub_version, BIG_ENDIAN) > 0
+		&& zfs_to_cpu64(uber->ub_version, BIG_ENDIAN) <= SPA_VERSION)
+		endian = BIG_ENDIAN;
+
+	if (endian == UNKNOWN_ENDIAN) {
+		printf("invalid uberblock magic\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	memset(&zc, 0, sizeof(zc));
+	zc.zc_word[0] = cpu_to_zfs64(offset, endian);
+	err = zio_checksum_verify(zc, ZIO_CHECKSUM_LABEL, endian,
+							  (char *) uber, UBERBLOCK_SIZE(data->vdev_ashift));
+
+	if (!err) {
+		/* Check that the data pointed by the rootbp is usable. */
+		void *osp = NULL;
+		size_t ospsize;
+		err = zio_read(&uber->ub_rootbp, endian, &osp, &ospsize, data);
+		free(osp);
+
+		if (!err && ospsize < OBJSET_PHYS_SIZE_V14) {
+			printf("uberblock rootbp points to invalid data\n");
+			return ZFS_ERR_BAD_FS;
+		}
+	}
+
+	return err;
+}
+
+/*
+ * Find the best uberblock.
+ * Return:
+ *	  Success - Pointer to the best uberblock.
+ *	  Failure - NULL
+ */
+static uberblock_t *find_bestub(char *ub_array, struct zfs_data *data)
+{
+	const uint64_t sector = data->vdev_phys_sector;
+	uberblock_t *ubbest = NULL;
+	uberblock_t *ubnext;
+	unsigned int i, offset, pickedub = 0;
+	int err = ZFS_ERR_NONE;
+
+	const unsigned int UBCOUNT = UBERBLOCK_COUNT(data->vdev_ashift);
+	const uint64_t UBBYTES = UBERBLOCK_SIZE(data->vdev_ashift);
+
+	for (i = 0; i < UBCOUNT; i++) {
+		ubnext = (uberblock_t *) (i * UBBYTES + ub_array);
+		offset = (sector << SPA_MINBLOCKSHIFT) + VDEV_PHYS_SIZE + (i * UBBYTES);
+
+		err = uberblock_verify(ubnext, offset, data);
+		if (err)
+			continue;
+
+		if (ubbest == NULL || vdev_uberblock_compare(ubnext, ubbest) > 0) {
+			ubbest = ubnext;
+			pickedub = i;
+		}
+	}
+
+	if (ubbest)
+		debug("zfs Found best uberblock at idx %d, txg %llu\n",
+			  pickedub, (unsigned long long) ubbest->ub_txg);
+
+	return ubbest;
+}
+
+static inline size_t
+get_psize(blkptr_t *bp, zfs_endian_t endian)
+{
+	return (((zfs_to_cpu64((bp)->blk_prop, endian) >> 16) & 0xffff) + 1)
+			<< SPA_MINBLOCKSHIFT;
+}
+
+static uint64_t
+dva_get_offset(dva_t *dva, zfs_endian_t endian)
+{
+	return zfs_to_cpu64((dva)->dva_word[1],
+							 endian) << SPA_MINBLOCKSHIFT;
+}
+
+/*
+ * Read a block of data based on the gang block address dva,
+ * and put its data in buf.
+ *
+ */
+static int
+zio_read_gang(blkptr_t *bp, zfs_endian_t endian, dva_t *dva, void *buf,
+			  struct zfs_data *data)
+{
+	zio_gbh_phys_t *zio_gb;
+	uint64_t offset, sector;
+	unsigned i;
+	int err;
+	zio_cksum_t zc;
+
+	memset(&zc, 0, sizeof(zc));
+
+	zio_gb = malloc(SPA_GANGBLOCKSIZE);
+	if (!zio_gb)
+		return ZFS_ERR_OUT_OF_MEMORY;
+
+	offset = dva_get_offset(dva, endian);
+	sector = DVA_OFFSET_TO_PHYS_SECTOR(offset);
+
+	/* read in the gang block header */
+	err = zfs_devread(sector, 0, SPA_GANGBLOCKSIZE, (char *) zio_gb);
+
+	if (err) {
+		free(zio_gb);
+		return err;
+	}
+
+	/* XXX */
+	/* self checksuming the gang block header */
+	ZIO_SET_CHECKSUM(&zc, DVA_GET_VDEV(dva),
+					 dva_get_offset(dva, endian), bp->blk_birth, 0);
+	err = zio_checksum_verify(zc, ZIO_CHECKSUM_GANG_HEADER, endian,
+							  (char *) zio_gb, SPA_GANGBLOCKSIZE);
+	if (err) {
+		free(zio_gb);
+		return err;
+	}
+
+	endian = (zfs_to_cpu64(bp->blk_prop, endian) >> 63) & 1;
+
+	for (i = 0; i < SPA_GBH_NBLKPTRS; i++) {
+		if (zio_gb->zg_blkptr[i].blk_birth == 0)
+			continue;
+
+		err = zio_read_data(&zio_gb->zg_blkptr[i], endian, buf, data);
+		if (err) {
+			free(zio_gb);
+			return err;
+		}
+		buf = (char *) buf + get_psize(&zio_gb->zg_blkptr[i], endian);
+	}
+	free(zio_gb);
+	return ZFS_ERR_NONE;
+}
+
+/*
+ * Read in a block of raw data to buf.
+ */
+static int
+zio_read_data(blkptr_t *bp, zfs_endian_t endian, void *buf,
+			  struct zfs_data *data)
+{
+	int i, psize;
+	int err = ZFS_ERR_NONE;
+
+	psize = get_psize(bp, endian);
+
+	/* pick a good dva from the block pointer */
+	for (i = 0; i < SPA_DVAS_PER_BP; i++) {
+		uint64_t offset, sector;
+
+		if (bp->blk_dva[i].dva_word[0] == 0 && bp->blk_dva[i].dva_word[1] == 0)
+			continue;
+
+		if ((zfs_to_cpu64(bp->blk_dva[i].dva_word[1], endian)>>63) & 1) {
+			err = zio_read_gang(bp, endian, &bp->blk_dva[i], buf, data);
+		} else {
+			/* read in a data block */
+			offset = dva_get_offset(&bp->blk_dva[i], endian);
+			sector = DVA_OFFSET_TO_PHYS_SECTOR(offset);
+
+			err = zfs_devread(sector, 0, psize, buf);
+		}
+
+		if (!err) {
+			/*Check the underlying checksum before we rule this DVA as "good"*/
+			uint32_t checkalgo = (zfs_to_cpu64((bp)->blk_prop, endian) >> 40) & 0xff;
+
+			err = zio_checksum_verify(bp->blk_cksum, checkalgo, endian, buf, psize);
+			if (!err)
+				return ZFS_ERR_NONE;
+		}
+
+		/* If read failed or checksum bad, reset the error.	 Hopefully we've got some more DVA's to try.*/
+	}
+
+	if (!err) {
+		printf("couldn't find a valid DVA\n");
+		err = ZFS_ERR_BAD_FS;
+	}
+
+	return err;
+}
+
+/*
+ * Read in a block of data, verify its checksum, decompress if needed,
+ * and put the uncompressed data in buf.
+ */
+static int
+zio_read(blkptr_t *bp, zfs_endian_t endian, void **buf,
+		 size_t *size, struct zfs_data *data)
+{
+	size_t lsize, psize;
+	unsigned int comp;
+	char *compbuf = NULL;
+	int err;
+
+	*buf = NULL;
+
+	comp = (zfs_to_cpu64((bp)->blk_prop, endian)>>32) & 0xff;
+	lsize = (BP_IS_HOLE(bp) ? 0 :
+			 (((zfs_to_cpu64((bp)->blk_prop, endian) & 0xffff) + 1)
+			  << SPA_MINBLOCKSHIFT));
+	psize = get_psize(bp, endian);
+
+	if (size)
+		*size = lsize;
+
+	if (comp >= ZIO_COMPRESS_FUNCTIONS) {
+		printf("compression algorithm %u not supported\n", (unsigned int) comp);
+		return ZFS_ERR_NOT_IMPLEMENTED_YET;
+	}
+
+	if (comp != ZIO_COMPRESS_OFF && decomp_table[comp].decomp_func == NULL) {
+		printf("compression algorithm %s not supported\n", decomp_table[comp].name);
+		return ZFS_ERR_NOT_IMPLEMENTED_YET;
+	}
+
+	if (comp != ZIO_COMPRESS_OFF) {
+		compbuf = malloc(psize);
+		if (!compbuf)
+			return ZFS_ERR_OUT_OF_MEMORY;
+	} else {
+		compbuf = *buf = malloc(lsize);
+	}
+
+	err = zio_read_data(bp, endian, compbuf, data);
+	if (err) {
+		free(compbuf);
+		*buf = NULL;
+		return err;
+	}
+
+	if (comp != ZIO_COMPRESS_OFF) {
+		*buf = malloc(lsize);
+		if (!*buf) {
+			free(compbuf);
+			return ZFS_ERR_OUT_OF_MEMORY;
+		}
+
+		err = decomp_table[comp].decomp_func(compbuf, *buf, psize, lsize);
+		free(compbuf);
+		if (err) {
+			free(*buf);
+			*buf = NULL;
+			return err;
+		}
+	}
+
+	return ZFS_ERR_NONE;
+}
+
+/*
+ * Get the block from a block id.
+ * push the block onto the stack.
+ *
+ */
+static int
+dmu_read(dnode_end_t *dn, uint64_t blkid, void **buf,
+		 zfs_endian_t *endian_out, struct zfs_data *data)
+{
+	int idx, level;
+	blkptr_t *bp_array = dn->dn.dn_blkptr;
+	int epbs = dn->dn.dn_indblkshift - SPA_BLKPTRSHIFT;
+	blkptr_t *bp;
+	void *tmpbuf = 0;
+	zfs_endian_t endian;
+	int err = ZFS_ERR_NONE;
+
+	bp = malloc(sizeof(blkptr_t));
+	if (!bp)
+		return ZFS_ERR_OUT_OF_MEMORY;
+
+	endian = dn->endian;
+	for (level = dn->dn.dn_nlevels - 1; level >= 0; level--) {
+		idx = (blkid >> (epbs * level)) & ((1 << epbs) - 1);
+		*bp = bp_array[idx];
+		if (bp_array != dn->dn.dn_blkptr) {
+			free(bp_array);
+			bp_array = 0;
+		}
+
+		if (BP_IS_HOLE(bp)) {
+			size_t size = zfs_to_cpu16(dn->dn.dn_datablkszsec,
+											dn->endian)
+				<< SPA_MINBLOCKSHIFT;
+			*buf = malloc(size);
+			if (*buf) {
+				err = ZFS_ERR_OUT_OF_MEMORY;
+				break;
+			}
+			memset(*buf, 0, size);
+			endian = (zfs_to_cpu64(bp->blk_prop, endian) >> 63) & 1;
+			break;
+		}
+		if (level == 0) {
+			err = zio_read(bp, endian, buf, 0, data);
+			endian = (zfs_to_cpu64(bp->blk_prop, endian) >> 63) & 1;
+			break;
+		}
+		err = zio_read(bp, endian, &tmpbuf, 0, data);
+		endian = (zfs_to_cpu64(bp->blk_prop, endian) >> 63) & 1;
+		if (err)
+			break;
+		bp_array = tmpbuf;
+	}
+	if (bp_array != dn->dn.dn_blkptr)
+		free(bp_array);
+	if (endian_out)
+		*endian_out = endian;
+
+	free(bp);
+	return err;
+}
+
+/*
+ * mzap_lookup: Looks up property described by "name" and returns the value
+ * in "value".
+ */
+static int
+mzap_lookup(mzap_phys_t *zapobj, zfs_endian_t endian,
+			int objsize, char *name, uint64_t * value)
+{
+	int i, chunks;
+	mzap_ent_phys_t *mzap_ent = zapobj->mz_chunk;
+
+	chunks = objsize / MZAP_ENT_LEN - 1;
+	for (i = 0; i < chunks; i++) {
+		if (strcmp(mzap_ent[i].mze_name, name) == 0) {
+			*value = zfs_to_cpu64(mzap_ent[i].mze_value, endian);
+			return ZFS_ERR_NONE;
+		}
+	}
+
+	printf("couldn't find '%s'\n", name);
+	return ZFS_ERR_FILE_NOT_FOUND;
+}
+
+static int
+mzap_iterate(mzap_phys_t *zapobj, zfs_endian_t endian, int objsize,
+			 int (*hook)(const char *name,
+						 uint64_t val,
+						 struct zfs_data *data),
+			 struct zfs_data *data)
+{
+	int i, chunks;
+	mzap_ent_phys_t *mzap_ent = zapobj->mz_chunk;
+
+	chunks = objsize / MZAP_ENT_LEN - 1;
+	for (i = 0; i < chunks; i++) {
+		if (hook(mzap_ent[i].mze_name,
+				 zfs_to_cpu64(mzap_ent[i].mze_value, endian),
+				 data))
+			return 1;
+	}
+
+	return 0;
+}
+
+static uint64_t
+zap_hash(uint64_t salt, const char *name)
+{
+	static uint64_t table[256];
+	const uint8_t *cp;
+	uint8_t c;
+	uint64_t crc = salt;
+
+	if (table[128] == 0) {
+		uint64_t *ct;
+		int i, j;
+		for (i = 0; i < 256; i++) {
+			for (ct = table + i, *ct = i, j = 8; j > 0; j--)
+				*ct = (*ct >> 1) ^ (-(*ct & 1) & ZFS_CRC64_POLY);
+		}
+	}
+
+	for (cp = (const uint8_t *) name; (c = *cp) != '\0'; cp++)
+		crc = (crc >> 8) ^ table[(crc ^ c) & 0xFF];
+
+	/*
+	 * Only use 28 bits, since we need 4 bits in the cookie for the
+	 * collision differentiator.  We MUST use the high bits, since
+	 * those are the onces that we first pay attention to when
+	 * chosing the bucket.
+	 */
+	crc &= ~((1ULL << (64 - ZAP_HASHBITS)) - 1);
+
+	return crc;
+}
+
+/*
+ * Only to be used on 8-bit arrays.
+ * array_len is actual len in bytes (not encoded le_value_length).
+ * buf is null-terminated.
+ */
+/* XXX */
+static int
+zap_leaf_array_equal(zap_leaf_phys_t *l, zfs_endian_t endian,
+					 int blksft, int chunk, int array_len, const char *buf)
+{
+	int bseen = 0;
+
+	while (bseen < array_len) {
+		struct zap_leaf_array *la = &ZAP_LEAF_CHUNK(l, blksft, chunk).l_array;
+		int toread = MIN(array_len - bseen, ZAP_LEAF_ARRAY_BYTES);
+
+		if (chunk >= ZAP_LEAF_NUMCHUNKS(blksft))
+			return 0;
+
+		if (memcmp(la->la_array, buf + bseen, toread) != 0)
+			break;
+		chunk = zfs_to_cpu16(la->la_next, endian);
+		bseen += toread;
+	}
+	return (bseen == array_len);
+}
+
+/* XXX */
+static int
+zap_leaf_array_get(zap_leaf_phys_t *l, zfs_endian_t endian, int blksft,
+				   int chunk, int array_len, char *buf)
+{
+	int bseen = 0;
+
+	while (bseen < array_len) {
+		struct zap_leaf_array *la = &ZAP_LEAF_CHUNK(l, blksft, chunk).l_array;
+		int toread = MIN(array_len - bseen, ZAP_LEAF_ARRAY_BYTES);
+
+		if (chunk >= ZAP_LEAF_NUMCHUNKS(blksft))
+			/* Don't use errno because this error is to be ignored.  */
+			return ZFS_ERR_BAD_FS;
+
+		memcpy(buf + bseen, la->la_array,  toread);
+		chunk = zfs_to_cpu16(la->la_next, endian);
+		bseen += toread;
+	}
+	return ZFS_ERR_NONE;
+}
+
+
+/*
+ * Given a zap_leaf_phys_t, walk thru the zap leaf chunks to get the
+ * value for the property "name".
+ *
+ */
+/* XXX */
+static int
+zap_leaf_lookup(zap_leaf_phys_t *l, zfs_endian_t endian,
+				int blksft, uint64_t h,
+				const char *name, uint64_t *value)
+{
+	uint16_t chunk;
+	struct zap_leaf_entry *le;
+
+	/* Verify if this is a valid leaf block */
+	if (zfs_to_cpu64(l->l_hdr.lh_block_type, endian) != ZBT_LEAF) {
+		printf("invalid leaf type\n");
+		return ZFS_ERR_BAD_FS;
+	}
+	if (zfs_to_cpu32(l->l_hdr.lh_magic, endian) != ZAP_LEAF_MAGIC) {
+		printf("invalid leaf magic\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	for (chunk = zfs_to_cpu16(l->l_hash[LEAF_HASH(blksft, h)], endian);
+		 chunk != CHAIN_END; chunk = le->le_next) {
+
+		if (chunk >= ZAP_LEAF_NUMCHUNKS(blksft)) {
+			printf("invalid chunk number\n");
+			return ZFS_ERR_BAD_FS;
+		}
+
+		le = ZAP_LEAF_ENTRY(l, blksft, chunk);
+
+		/* Verify the chunk entry */
+		if (le->le_type != ZAP_CHUNK_ENTRY) {
+			printf("invalid chunk entry\n");
+			return ZFS_ERR_BAD_FS;
+		}
+
+		if (zfs_to_cpu64(le->le_hash, endian) != h)
+			continue;
+
+		if (zap_leaf_array_equal(l, endian, blksft,
+								 zfs_to_cpu16(le->le_name_chunk, endian),
+								 zfs_to_cpu16(le->le_name_length, endian),
+								 name)) {
+			struct zap_leaf_array *la;
+
+			if (le->le_int_size != 8 || le->le_value_length != 1) {
+				printf("invalid leaf chunk entry\n");
+				return ZFS_ERR_BAD_FS;
+			}
+			/* get the uint64_t property value */
+			la = &ZAP_LEAF_CHUNK(l, blksft, le->le_value_chunk).l_array;
+
+			*value = be64_to_cpu(la->la_array64);
+
+			return ZFS_ERR_NONE;
+		}
+	}
+
+	printf("couldn't find '%s'\n", name);
+	return ZFS_ERR_FILE_NOT_FOUND;
+}
+
+
+/* Verify if this is a fat zap header block */
+static int
+zap_verify(zap_phys_t *zap)
+{
+	if (zap->zap_magic != (uint64_t) ZAP_MAGIC) {
+		printf("bad ZAP magic\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	if (zap->zap_flags != 0) {
+		printf("bad ZAP flags\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	if (zap->zap_salt == 0) {
+		printf("bad ZAP salt\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	return ZFS_ERR_NONE;
+}
+
+/*
+ * Fat ZAP lookup
+ *
+ */
+/* XXX */
+static int
+fzap_lookup(dnode_end_t *zap_dnode, zap_phys_t *zap,
+			char *name, uint64_t *value, struct zfs_data *data)
+{
+	void *l;
+	uint64_t hash, idx, blkid;
+	int blksft = zfs_log2(zfs_to_cpu16(zap_dnode->dn.dn_datablkszsec,
+											zap_dnode->endian) << DNODE_SHIFT);
+	int err;
+	zfs_endian_t leafendian;
+
+	err = zap_verify(zap);
+	if (err)
+		return err;
+
+	hash = zap_hash(zap->zap_salt, name);
+
+	/* get block id from index */
+	if (zap->zap_ptrtbl.zt_numblks != 0) {
+		printf("external pointer tables not supported\n");
+		return ZFS_ERR_NOT_IMPLEMENTED_YET;
+	}
+	idx = ZAP_HASH_IDX(hash, zap->zap_ptrtbl.zt_shift);
+	blkid = ((uint64_t *) zap)[idx + (1 << (blksft - 3 - 1))];
+
+	/* Get the leaf block */
+	if ((1U << blksft) < sizeof(zap_leaf_phys_t)) {
+		printf("ZAP leaf is too small\n");
+		return ZFS_ERR_BAD_FS;
+	}
+	err = dmu_read(zap_dnode, blkid, &l, &leafendian, data);
+	if (err)
+		return err;
+
+	err = zap_leaf_lookup(l, leafendian, blksft, hash, name, value);
+	free(l);
+	return err;
+}
+
+/* XXX */
+static int
+fzap_iterate(dnode_end_t *zap_dnode, zap_phys_t *zap,
+			 int (*hook)(const char *name,
+						 uint64_t val,
+						 struct zfs_data *data),
+			 struct zfs_data *data)
+{
+	zap_leaf_phys_t *l;
+	void *l_in;
+	uint64_t idx, blkid;
+	uint16_t chunk;
+	int blksft = zfs_log2(zfs_to_cpu16(zap_dnode->dn.dn_datablkszsec,
+											zap_dnode->endian) << DNODE_SHIFT);
+	int err;
+	zfs_endian_t endian;
+
+	if (zap_verify(zap))
+		return 0;
+
+	/* get block id from index */
+	if (zap->zap_ptrtbl.zt_numblks != 0) {
+		printf("external pointer tables not supported\n");
+		return 0;
+	}
+	/* Get the leaf block */
+	if ((1U << blksft) < sizeof(zap_leaf_phys_t)) {
+		printf("ZAP leaf is too small\n");
+		return 0;
+	}
+	for (idx = 0; idx < zap->zap_ptrtbl.zt_numblks; idx++) {
+		blkid = ((uint64_t *) zap)[idx + (1 << (blksft - 3 - 1))];
+
+		err = dmu_read(zap_dnode, blkid, &l_in, &endian, data);
+		l = l_in;
+		if (err)
+			continue;
+
+		/* Verify if this is a valid leaf block */
+		if (zfs_to_cpu64(l->l_hdr.lh_block_type, endian) != ZBT_LEAF) {
+			free(l);
+			continue;
+		}
+		if (zfs_to_cpu32(l->l_hdr.lh_magic, endian) != ZAP_LEAF_MAGIC) {
+			free(l);
+			continue;
+		}
+
+		for (chunk = 0; chunk < ZAP_LEAF_NUMCHUNKS(blksft); chunk++) {
+			char *buf;
+			struct zap_leaf_array *la;
+			struct zap_leaf_entry *le;
+			uint64_t val;
+			le = ZAP_LEAF_ENTRY(l, blksft, chunk);
+
+			/* Verify the chunk entry */
+			if (le->le_type != ZAP_CHUNK_ENTRY)
+				continue;
+
+			buf = malloc(zfs_to_cpu16(le->le_name_length, endian)
+						 + 1);
+			if (zap_leaf_array_get(l, endian, blksft, le->le_name_chunk,
+								   le->le_name_length, buf)) {
+				free(buf);
+				continue;
+			}
+			buf[le->le_name_length] = 0;
+
+			if (le->le_int_size != 8
+				|| zfs_to_cpu16(le->le_value_length, endian) != 1)
+				continue;
+
+			/* get the uint64_t property value */
+			la = &ZAP_LEAF_CHUNK(l, blksft, le->le_value_chunk).l_array;
+			val = be64_to_cpu(la->la_array64);
+			if (hook(buf, val, data))
+				return 1;
+			free(buf);
+		}
+	}
+	return 0;
+}
+
+
+/*
+ * Read in the data of a zap object and find the value for a matching
+ * property name.
+ *
+ */
+static int
+zap_lookup(dnode_end_t *zap_dnode, char *name, uint64_t *val,
+		   struct zfs_data *data)
+{
+	uint64_t block_type;
+	int size;
+	void *zapbuf;
+	int err;
+	zfs_endian_t endian;
+
+	/* Read in the first block of the zap object data. */
+	size = zfs_to_cpu16(zap_dnode->dn.dn_datablkszsec,
+							 zap_dnode->endian) << SPA_MINBLOCKSHIFT;
+	err = dmu_read(zap_dnode, 0, &zapbuf, &endian, data);
+	if (err)
+		return err;
+	block_type = zfs_to_cpu64(*((uint64_t *) zapbuf), endian);
+
+	if (block_type == ZBT_MICRO) {
+		err = (mzap_lookup(zapbuf, endian, size, name, val));
+		free(zapbuf);
+		return err;
+	} else if (block_type == ZBT_HEADER) {
+		/* this is a fat zap */
+		err = (fzap_lookup(zap_dnode, zapbuf, name, val, data));
+		free(zapbuf);
+		return err;
+	}
+
+	printf("unknown ZAP type\n");
+	return ZFS_ERR_BAD_FS;
+}
+
+static int
+zap_iterate(dnode_end_t *zap_dnode,
+			int (*hook)(const char *name, uint64_t val,
+						struct zfs_data *data),
+			struct zfs_data *data)
+{
+	uint64_t block_type;
+	int size;
+	void *zapbuf;
+	int err;
+	int ret;
+	zfs_endian_t endian;
+
+	/* Read in the first block of the zap object data. */
+	size = zfs_to_cpu16(zap_dnode->dn.dn_datablkszsec, zap_dnode->endian) << SPA_MINBLOCKSHIFT;
+	err = dmu_read(zap_dnode, 0, &zapbuf, &endian, data);
+	if (err)
+		return 0;
+	block_type = zfs_to_cpu64(*((uint64_t *) zapbuf), endian);
+
+	if (block_type == ZBT_MICRO) {
+		ret = mzap_iterate(zapbuf, endian, size, hook, data);
+		free(zapbuf);
+		return ret;
+	} else if (block_type == ZBT_HEADER) {
+		/* this is a fat zap */
+		ret = fzap_iterate(zap_dnode, zapbuf, hook, data);
+		free(zapbuf);
+		return ret;
+	}
+	printf("unknown ZAP type\n");
+	return 0;
+}
+
+
+/*
+ * Get the dnode of an object number from the metadnode of an object set.
+ *
+ * Input
+ *	mdn - metadnode to get the object dnode
+ *	objnum - object number for the object dnode
+ *	buf - data buffer that holds the returning dnode
+ */
+static int
+dnode_get(dnode_end_t *mdn, uint64_t objnum, uint8_t type,
+		  dnode_end_t *buf, struct zfs_data *data)
+{
+	uint64_t blkid, blksz;	/* the block id this object dnode is in */
+	int epbs;			/* shift of number of dnodes in a block */
+	int idx;			/* index within a block */
+	void *dnbuf;
+	int err;
+	zfs_endian_t endian;
+
+	blksz = zfs_to_cpu16(mdn->dn.dn_datablkszsec,
+							  mdn->endian) << SPA_MINBLOCKSHIFT;
+
+	epbs = zfs_log2(blksz) - DNODE_SHIFT;
+	blkid = objnum >> epbs;
+	idx = objnum & ((1 << epbs) - 1);
+
+	if (data->dnode_buf != NULL && memcmp(data->dnode_mdn, mdn,
+										  sizeof(*mdn)) == 0
+		&& objnum >= data->dnode_start && objnum < data->dnode_end) {
+		memmove(&(buf->dn), &(data->dnode_buf)[idx], DNODE_SIZE);
+		buf->endian = data->dnode_endian;
+		if (type && buf->dn.dn_type != type)  {
+			printf("incorrect dnode type: %02X != %02x\n", buf->dn.dn_type, type);
+			return ZFS_ERR_BAD_FS;
+		}
+		return ZFS_ERR_NONE;
+	}
+
+	err = dmu_read(mdn, blkid, &dnbuf, &endian, data);
+	if (err)
+		return err;
+
+	free(data->dnode_buf);
+	free(data->dnode_mdn);
+	data->dnode_mdn = malloc(sizeof(*mdn));
+	if (!data->dnode_mdn) {
+		data->dnode_buf = 0;
+	} else {
+		memcpy(data->dnode_mdn, mdn, sizeof(*mdn));
+		data->dnode_buf = dnbuf;
+		data->dnode_start = blkid << epbs;
+		data->dnode_end = (blkid + 1) << epbs;
+		data->dnode_endian = endian;
+	}
+
+	memmove(&(buf->dn), (dnode_phys_t *) dnbuf + idx, DNODE_SIZE);
+	buf->endian = endian;
+	if (type && buf->dn.dn_type != type) {
+		printf("incorrect dnode type\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	return ZFS_ERR_NONE;
+}
+
+/*
+ * Get the file dnode for a given file name where mdn is the meta dnode
+ * for this ZFS object set. When found, place the file dnode in dn.
+ * The 'path' argument will be mangled.
+ *
+ */
+static int
+dnode_get_path(dnode_end_t *mdn, const char *path_in, dnode_end_t *dn,
+			   struct zfs_data *data)
+{
+	uint64_t objnum, version;
+	char *cname, ch;
+	int err = ZFS_ERR_NONE;
+	char *path, *path_buf;
+	struct dnode_chain {
+		struct dnode_chain *next;
+		dnode_end_t dn;
+	};
+	struct dnode_chain *dnode_path = 0, *dn_new, *root;
+
+	dn_new = malloc(sizeof(*dn_new));
+	if (!dn_new)
+		return ZFS_ERR_OUT_OF_MEMORY;
+	dn_new->next = 0;
+	dnode_path = root = dn_new;
+
+	err = dnode_get(mdn, MASTER_NODE_OBJ, DMU_OT_MASTER_NODE,
+					&(dnode_path->dn), data);
+	if (err) {
+		free(dn_new);
+		return err;
+	}
+
+	err = zap_lookup(&(dnode_path->dn), ZPL_VERSION_STR, &version, data);
+	if (err) {
+		free(dn_new);
+		return err;
+	}
+	if (version > ZPL_VERSION) {
+		free(dn_new);
+		printf("too new ZPL version\n");
+		return ZFS_ERR_NOT_IMPLEMENTED_YET;
+	}
+
+	err = zap_lookup(&(dnode_path->dn), ZFS_ROOT_OBJ, &objnum, data);
+	if (err) {
+		free(dn_new);
+		return err;
+	}
+
+	err = dnode_get(mdn, objnum, 0, &(dnode_path->dn), data);
+	if (err) {
+		free(dn_new);
+		return err;
+	}
+
+	path = path_buf = strdup(path_in);
+	if (!path_buf) {
+		free(dn_new);
+		return ZFS_ERR_OUT_OF_MEMORY;
+	}
+
+	while (1) {
+		/* skip leading slashes */
+		while (*path == '/')
+			path++;
+		if (!*path)
+			break;
+		/* get the next component name */
+		cname = path;
+		while (*path && *path != '/')
+			path++;
+		/* Skip dot.  */
+		if (cname + 1 == path && cname[0] == '.')
+			continue;
+		/* Handle double dot.  */
+		if (cname + 2 == path && cname[0] == '.' && cname[1] == '.')  {
+			if (dn_new->next) {
+				dn_new = dnode_path;
+				dnode_path = dn_new->next;
+				free(dn_new);
+			} else {
+				printf("can't resolve ..\n");
+				err = ZFS_ERR_FILE_NOT_FOUND;
+				break;
+			}
+			continue;
+		}
+
+		ch = *path;
+		*path = 0;		/* ensure null termination */
+
+		if (dnode_path->dn.dn.dn_type != DMU_OT_DIRECTORY_CONTENTS) {
+			free(path_buf);
+			printf("not a directory\n");
+			return ZFS_ERR_BAD_FILE_TYPE;
+		}
+		err = zap_lookup(&(dnode_path->dn), cname, &objnum, data);
+		if (err)
+			break;
+
+		dn_new = malloc(sizeof(*dn_new));
+		if (!dn_new) {
+			err = ZFS_ERR_OUT_OF_MEMORY;
+			break;
+		}
+		dn_new->next = dnode_path;
+		dnode_path = dn_new;
+
+		objnum = ZFS_DIRENT_OBJ(objnum);
+		err = dnode_get(mdn, objnum, 0, &(dnode_path->dn), data);
+		if (err)
+			break;
+
+		*path = ch;
+	}
+
+	if (!err)
+		memcpy(dn, &(dnode_path->dn), sizeof(*dn));
+
+	while (dnode_path) {
+		dn_new = dnode_path->next;
+		free(dnode_path);
+		dnode_path = dn_new;
+	}
+	free(path_buf);
+	return err;
+}
+
+
+/*
+ * Given a MOS metadnode, get the metadnode of a given filesystem name (fsname),
+ * e.g. pool/rootfs, or a given object number (obj), e.g. the object number
+ * of pool/rootfs.
+ *
+ * If no fsname and no obj are given, return the DSL_DIR metadnode.
+ * If fsname is given, return its metadnode and its matching object number.
+ * If only obj is given, return the metadnode for this object number.
+ *
+ */
+static int
+get_filesystem_dnode(dnode_end_t *mosmdn, char *fsname,
+					 dnode_end_t *mdn, struct zfs_data *data)
+{
+	uint64_t objnum;
+	int err;
+
+	err = dnode_get(mosmdn, DMU_POOL_DIRECTORY_OBJECT,
+					DMU_OT_OBJECT_DIRECTORY, mdn, data);
+	if (err)
+		return err;
+
+	err = zap_lookup(mdn, DMU_POOL_ROOT_DATASET, &objnum, data);
+	if (err)
+		return err;
+
+	err = dnode_get(mosmdn, objnum, DMU_OT_DSL_DIR, mdn, data);
+	if (err)
+		return err;
+
+	while (*fsname) {
+		uint64_t childobj;
+		char *cname, ch;
+
+		while (*fsname == '/')
+			fsname++;
+
+		if (!*fsname || *fsname == '@')
+			break;
+
+		cname = fsname;
+		while (*fsname && !isspace(*fsname) && *fsname != '/')
+			fsname++;
+		ch = *fsname;
+		*fsname = 0;
+
+		childobj = zfs_to_cpu64((((dsl_dir_phys_t *) DN_BONUS(&mdn->dn)))->dd_child_dir_zapobj, mdn->endian);
+		err = dnode_get(mosmdn, childobj,
+						DMU_OT_DSL_DIR_CHILD_MAP, mdn, data);
+		if (err)
+			return err;
+
+		err = zap_lookup(mdn, cname, &objnum, data);
+		if (err)
+			return err;
+
+		err = dnode_get(mosmdn, objnum, DMU_OT_DSL_DIR, mdn, data);
+		if (err)
+			return err;
+
+		*fsname = ch;
+	}
+	return ZFS_ERR_NONE;
+}
+
+static int
+make_mdn(dnode_end_t *mdn, struct zfs_data *data)
+{
+	void *osp;
+	blkptr_t *bp;
+	size_t ospsize;
+	int err;
+
+	bp = &(((dsl_dataset_phys_t *) DN_BONUS(&mdn->dn))->ds_bp);
+	err = zio_read(bp, mdn->endian, &osp, &ospsize, data);
+	if (err)
+		return err;
+	if (ospsize < OBJSET_PHYS_SIZE_V14) {
+		free(osp);
+		printf("too small osp\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	mdn->endian = (zfs_to_cpu64(bp->blk_prop, mdn->endian)>>63) & 1;
+	memmove((char *) &(mdn->dn),
+			(char *) &((objset_phys_t *) osp)->os_meta_dnode, DNODE_SIZE);
+	free(osp);
+	return ZFS_ERR_NONE;
+}
+
+static int
+dnode_get_fullpath(const char *fullpath, dnode_end_t *mdn,
+				   uint64_t *mdnobj, dnode_end_t *dn, int *isfs,
+				   struct zfs_data *data)
+{
+	char *fsname, *snapname;
+	const char *ptr_at, *filename;
+	uint64_t headobj;
+	int err;
+
+	ptr_at = strchr(fullpath, '@');
+	if (!ptr_at) {
+		*isfs = 1;
+		filename = 0;
+		snapname = 0;
+		fsname = strdup(fullpath);
+	} else {
+		const char *ptr_slash = strchr(ptr_at, '/');
+
+		*isfs = 0;
+		fsname = malloc(ptr_at - fullpath + 1);
+		if (!fsname)
+			return ZFS_ERR_OUT_OF_MEMORY;
+		memcpy(fsname, fullpath, ptr_at - fullpath);
+		fsname[ptr_at - fullpath] = 0;
+		if (ptr_at[1] && ptr_at[1] != '/') {
+			snapname = malloc(ptr_slash - ptr_at);
+			if (!snapname) {
+				free(fsname);
+				return ZFS_ERR_OUT_OF_MEMORY;
+			}
+			memcpy(snapname, ptr_at + 1, ptr_slash - ptr_at - 1);
+			snapname[ptr_slash - ptr_at - 1] = 0;
+		} else {
+			snapname = 0;
+		}
+		if (ptr_slash)
+			filename = ptr_slash;
+		else
+			filename = "/";
+		printf("zfs fsname = '%s' snapname='%s' filename = '%s'\n",
+			   fsname, snapname, filename);
+	}
+
+
+	err = get_filesystem_dnode(&(data->mos), fsname, dn, data);
+
+	if (err) {
+		free(fsname);
+		free(snapname);
+		return err;
+	}
+
+	headobj = zfs_to_cpu64(((dsl_dir_phys_t *) DN_BONUS(&dn->dn))->dd_head_dataset_obj, dn->endian);
+
+	err = dnode_get(&(data->mos), headobj, DMU_OT_DSL_DATASET, mdn, data);
+	if (err) {
+		free(fsname);
+		free(snapname);
+		return err;
+	}
+
+	if (snapname) {
+		uint64_t snapobj;
+
+		snapobj = zfs_to_cpu64(((dsl_dataset_phys_t *) DN_BONUS(&mdn->dn))->ds_snapnames_zapobj, mdn->endian);
+
+		err = dnode_get(&(data->mos), snapobj,
+						DMU_OT_DSL_DS_SNAP_MAP, mdn, data);
+		if (!err)
+			err = zap_lookup(mdn, snapname, &headobj, data);
+		if (!err)
+			err = dnode_get(&(data->mos), headobj, DMU_OT_DSL_DATASET, mdn, data);
+		if (err) {
+			free(fsname);
+			free(snapname);
+			return err;
+		}
+	}
+
+	if (mdnobj)
+		*mdnobj = headobj;
+
+	make_mdn(mdn, data);
+
+	if (*isfs) {
+		free(fsname);
+		free(snapname);
+		return ZFS_ERR_NONE;
+	}
+	err = dnode_get_path(mdn, filename, dn, data);
+	free(fsname);
+	free(snapname);
+	return err;
+}
+
+/*
+ * For a given XDR packed nvlist, verify the first 4 bytes and move on.
+ *
+ * An XDR packed nvlist is encoded as (comments from nvs_xdr_create) :
+ *
+ *		encoding method/host endian		(4 bytes)
+ *		nvl_version						(4 bytes)
+ *		nvl_nvflag						(4 bytes)
+ *	encoded nvpairs:
+ *		encoded size of the nvpair		(4 bytes)
+ *		decoded size of the nvpair		(4 bytes)
+ *		name string size				(4 bytes)
+ *		name string data				(sizeof(NV_ALIGN4(string))
+ *		data type						(4 bytes)
+ *		# of elements in the nvpair		(4 bytes)
+ *		data
+ *		2 zero's for the last nvpair
+ *		(end of the entire list)	(8 bytes)
+ *
+ */
+
+static int
+nvlist_find_value(char *nvlist, char *name, int valtype, char **val,
+				  size_t *size_out, size_t *nelm_out)
+{
+	int name_len, type, encode_size;
+	char *nvpair, *nvp_name;
+
+	/* Verify if the 1st and 2nd byte in the nvlist are valid. */
+	/* NOTE: independently of what endianness header announces all
+	   subsequent values are big-endian.  */
+	if (nvlist[0] != NV_ENCODE_XDR || (nvlist[1] != NV_LITTLE_ENDIAN
+									   && nvlist[1] != NV_BIG_ENDIAN)) {
+		printf("zfs incorrect nvlist header\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	/* skip the header, nvl_version, and nvl_nvflag */
+	nvlist = nvlist + 4 * 3;
+	/*
+	 * Loop thru the nvpair list
+	 * The XDR representation of an integer is in big-endian byte order.
+	 */
+	while ((encode_size = be32_to_cpu(*(uint32_t *) nvlist))) {
+		int nelm;
+
+		nvpair = nvlist + 4 * 2;	/* skip the encode/decode size */
+
+		name_len = be32_to_cpu(*(uint32_t *) nvpair);
+		nvpair += 4;
+
+		nvp_name = nvpair;
+		nvpair = nvpair + ((name_len + 3) & ~3);	/* align */
+
+		type = be32_to_cpu(*(uint32_t *) nvpair);
+		nvpair += 4;
+
+		nelm = be32_to_cpu(*(uint32_t *) nvpair);
+		if (nelm < 1) {
+			printf("empty nvpair\n");
+			return ZFS_ERR_BAD_FS;
+		}
+
+		nvpair += 4;
+
+		if ((strncmp(nvp_name, name, name_len) == 0) && type == valtype) {
+			*val = nvpair;
+			*size_out = encode_size;
+			if (nelm_out)
+				*nelm_out = nelm;
+			return 1;
+		}
+
+		nvlist += encode_size;	/* goto the next nvpair */
+	}
+	return 0;
+}
+
+int
+zfs_nvlist_lookup_uint64(char *nvlist, char *name, uint64_t *out)
+{
+	char *nvpair;
+	size_t size;
+	int found;
+
+	found = nvlist_find_value(nvlist, name, DATA_TYPE_UINT64, &nvpair, &size, 0);
+	if (!found)
+		return 0;
+	if (size < sizeof(uint64_t)) {
+		printf("invalid uint64\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	*out = be64_to_cpu(*(uint64_t *) nvpair);
+	return 1;
+}
+
+char *
+zfs_nvlist_lookup_string(char *nvlist, char *name)
+{
+	char *nvpair;
+	char *ret;
+	size_t slen;
+	size_t size;
+	int found;
+
+	found = nvlist_find_value(nvlist, name, DATA_TYPE_STRING, &nvpair, &size, 0);
+	if (!found)
+		return 0;
+	if (size < 4) {
+		printf("invalid string\n");
+		return 0;
+	}
+	slen = be32_to_cpu(*(uint32_t *) nvpair);
+	if (slen > size - 4)
+		slen = size - 4;
+	ret = malloc(slen + 1);
+	if (!ret)
+		return 0;
+	memcpy(ret, nvpair + 4, slen);
+	ret[slen] = 0;
+	return ret;
+}
+
+char *
+zfs_nvlist_lookup_nvlist(char *nvlist, char *name)
+{
+	char *nvpair;
+	char *ret;
+	size_t size;
+	int found;
+
+	found = nvlist_find_value(nvlist, name, DATA_TYPE_NVLIST, &nvpair,
+							  &size, 0);
+	if (!found)
+		return 0;
+	ret = calloc(1, size + 3 * sizeof(uint32_t));
+	if (!ret)
+		return 0;
+	memcpy(ret, nvlist, sizeof(uint32_t));
+
+	memcpy(ret + sizeof(uint32_t), nvpair, size);
+	return ret;
+}
+
+int
+zfs_nvlist_lookup_nvlist_array_get_nelm(char *nvlist, char *name)
+{
+	char *nvpair;
+	size_t nelm, size;
+	int found;
+
+	found = nvlist_find_value(nvlist, name, DATA_TYPE_NVLIST, &nvpair,
+							  &size, &nelm);
+	if (!found)
+		return -1;
+	return nelm;
+}
+
+char *
+zfs_nvlist_lookup_nvlist_array(char *nvlist, char *name,
+									size_t index)
+{
+	char *nvpair, *nvpairptr;
+	int found;
+	char *ret;
+	size_t size;
+	unsigned i;
+	size_t nelm;
+
+	found = nvlist_find_value(nvlist, name, DATA_TYPE_NVLIST, &nvpair,
+							  &size, &nelm);
+	if (!found)
+		return 0;
+	if (index >= nelm) {
+		printf("trying to lookup past nvlist array\n");
+		return 0;
+	}
+
+	nvpairptr = nvpair;
+
+	for (i = 0; i < index; i++) {
+		uint32_t encode_size;
+
+		/* skip the header, nvl_version, and nvl_nvflag */
+		nvpairptr = nvpairptr + 4 * 2;
+
+		while (nvpairptr < nvpair + size
+			   && (encode_size = be32_to_cpu(*(uint32_t *) nvpairptr)))
+			nvlist += encode_size;	/* goto the next nvpair */
+
+		nvlist = nvlist + 4 * 2;	/* skip the ending 2 zeros - 8 bytes */
+	}
+
+	if (nvpairptr >= nvpair + size
+		|| nvpairptr + be32_to_cpu(*(uint32_t *) (nvpairptr + 4 * 2))
+		>= nvpair + size) {
+		printf("incorrect nvlist array\n");
+		return 0;
+	}
+
+	ret = calloc(1, be32_to_cpu(*(uint32_t *) (nvpairptr + 4 * 2))
+				 + 3 * sizeof(uint32_t));
+	if (!ret)
+		return 0;
+	memcpy(ret, nvlist, sizeof(uint32_t));
+
+	memcpy(ret + sizeof(uint32_t), nvpairptr, size);
+	return ret;
+}
+
+static int
+int_zfs_fetch_nvlist(struct zfs_data *data, char **nvlist)
+{
+	int err;
+
+	*nvlist = malloc(VDEV_PHYS_SIZE);
+	/* Read in the vdev name-value pair list (112K). */
+	err = zfs_devread(data->vdev_phys_sector, 0, VDEV_PHYS_SIZE, *nvlist);
+	if (err) {
+		free(*nvlist);
+		*nvlist = 0;
+		return err;
+	}
+	return ZFS_ERR_NONE;
+}
+
+/*
+ * Check the disk label information and retrieve needed vdev name-value pairs.
+ *
+ */
+static int
+check_pool_label(struct zfs_data *data)
+{
+	uint64_t pool_state;
+	char *nvlist;			/* for the pool */
+	char *vdevnvlist;		/* for the vdev */
+	uint64_t diskguid;
+	uint64_t version;
+	int found;
+	int err;
+
+	err = int_zfs_fetch_nvlist(data, &nvlist);
+	if (err)
+		return err;
+
+	found = zfs_nvlist_lookup_uint64(nvlist, ZPOOL_CONFIG_POOL_STATE,
+										  &pool_state);
+	if (!found) {
+		free(nvlist);
+		printf("zfs pool state not found\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	if (pool_state == POOL_STATE_DESTROYED) {
+		free(nvlist);
+		printf("zpool is marked as destroyed\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	data->label_txg = 0;
+	found = zfs_nvlist_lookup_uint64(nvlist, ZPOOL_CONFIG_POOL_TXG,
+										  &data->label_txg);
+	if (!found) {
+		free(nvlist);
+		printf("zfs pool txg not found\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	/* not an active device */
+	if (data->label_txg == 0) {
+		free(nvlist);
+		printf("zpool is not active\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	found = zfs_nvlist_lookup_uint64(nvlist, ZPOOL_CONFIG_VERSION,
+										  &version);
+	if (!found) {
+		free(nvlist);
+		printf("zpool config version not found\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	if (version > SPA_VERSION) {
+		free(nvlist);
+		printf("SPA version too new %llu > %llu\n",
+			   (unsigned long long) version,
+			   (unsigned long long) SPA_VERSION);
+		return ZFS_ERR_NOT_IMPLEMENTED_YET;
+	}
+
+	vdevnvlist = zfs_nvlist_lookup_nvlist(nvlist, ZPOOL_CONFIG_VDEV_TREE);
+	if (!vdevnvlist) {
+		free(nvlist);
+		printf("ZFS config vdev tree not found\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	found = zfs_nvlist_lookup_uint64(vdevnvlist, ZPOOL_CONFIG_ASHIFT,
+										  &data->vdev_ashift);
+	free(vdevnvlist);
+	if (!found) {
+		free(nvlist);
+		printf("ZPOOL config ashift not found\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	found = zfs_nvlist_lookup_uint64(nvlist, ZPOOL_CONFIG_GUID, &diskguid);
+	if (!found) {
+		free(nvlist);
+		printf("ZPOOL config guid not found\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	found = zfs_nvlist_lookup_uint64(nvlist, ZPOOL_CONFIG_POOL_GUID, &data->pool_guid);
+	if (!found) {
+		free(nvlist);
+		printf("ZPOOL config pool guid not found\n");
+		return ZFS_ERR_BAD_FS;
+	}
+
+	free(nvlist);
+
+	printf("ZFS Pool GUID: %llu (%016llx) Label: GUID: %llu (%016llx), txg: %llu, SPA v%llu, ashift: %llu\n",
+		   (unsigned long long) data->pool_guid,
+		   (unsigned long long) data->pool_guid,
+		   (unsigned long long) diskguid,
+		   (unsigned long long) diskguid,
+		   (unsigned long long) data->label_txg,
+		   (unsigned long long) version,
+		   (unsigned long long) data->vdev_ashift);
+
+	return ZFS_ERR_NONE;
+}
+
+/*
+ * vdev_label_start returns the physical disk offset (in bytes) of
+ * label "l".
+ */
+static uint64_t vdev_label_start(uint64_t psize, int l)
+{
+	return (l * sizeof(vdev_label_t) + (l < VDEV_LABELS / 2 ?
+										0 : psize -
+										VDEV_LABELS * sizeof(vdev_label_t)));
+}
+
+void
+zfs_unmount(struct zfs_data *data)
+{
+	free(data->dnode_buf);
+	free(data->dnode_mdn);
+	free(data->file_buf);
+	free(data);
+}
+
+/*
+ * zfs_mount() locates a valid uberblock of the root pool and read in its MOS
+ * to the memory address MOS.
+ *
+ */
+struct zfs_data *
+zfs_mount(device_t dev)
+{
+	struct zfs_data *data = 0;
+	int label = 0, bestlabel = -1;
+	char *ub_array;
+	uberblock_t *ubbest;
+	uberblock_t *ubcur = NULL;
+	void *osp = 0;
+	size_t ospsize;
+	int err;
+
+	data = malloc(sizeof(*data));
+	if (!data)
+		return 0;
+	memset(data, 0, sizeof(*data));
+
+	ub_array = malloc(VDEV_UBERBLOCK_RING);
+	if (!ub_array) {
+		zfs_unmount(data);
+		return 0;
+	}
+
+	ubbest = malloc(sizeof(*ubbest));
+	if (!ubbest) {
+		zfs_unmount(data);
+		return 0;
+	}
+	memset(ubbest, 0, sizeof(*ubbest));
+
+	/*
+	 * some eltorito stacks don't give us a size and
+	 * we end up setting the size to MAXUINT, further
+	 * some of these devices stop working once a single
+	 * read past the end has been issued. Checking
+	 * for a maximum part_length and skipping the backup
+	 * labels at the end of the slice/partition/device
+	 * avoids breaking down on such devices.
+	 */
+	const int vdevnum =
+		dev->part_length == 0 ?
+		VDEV_LABELS / 2 : VDEV_LABELS;
+
+	/* Size in bytes of the device (disk or partition) aligned to label size*/
+	uint64_t device_size =
+		dev->part_length << SECTOR_BITS;
+
+	const uint64_t alignedbytes =
+		P2ALIGN(device_size, (uint64_t) sizeof(vdev_label_t));
+
+	for (label = 0; label < vdevnum; label++) {
+		uint64_t labelstartbytes = vdev_label_start(alignedbytes, label);
+		uint64_t labelstart = labelstartbytes >> SECTOR_BITS;
+
+		debug("zfs reading label %d at sector %llu (byte %llu)\n",
+			  label, (unsigned long long) labelstart,
+			  (unsigned long long) labelstartbytes);
+
+		data->vdev_phys_sector = labelstart +
+			((VDEV_SKIP_SIZE + VDEV_BOOT_HEADER_SIZE) >> SECTOR_BITS);
+
+		err = check_pool_label(data);
+		if (err) {
+			printf("zfs error checking label %d\n", label);
+			continue;
+		}
+
+		/* Read in the uberblock ring (128K). */
+		err = zfs_devread(data->vdev_phys_sector  +
+						  (VDEV_PHYS_SIZE >> SECTOR_BITS),
+						  0, VDEV_UBERBLOCK_RING, ub_array);
+		if (err) {
+			printf("zfs error reading uberblock ring for label %d\n", label);
+			continue;
+		}
+
+		ubcur = find_bestub(ub_array, data);
+		if (!ubcur) {
+			printf("zfs No good uberblocks found in label %d\n", label);
+			continue;
+		}
+
+		if (vdev_uberblock_compare(ubcur, ubbest) > 0) {
+			/* Looks like the block is good, so use it.*/
+			memcpy(ubbest, ubcur, sizeof(*ubbest));
+			bestlabel = label;
+			debug("zfs Current best uberblock found in label %d\n", label);
+		}
+	}
+	free(ub_array);
+
+	/* We zero'd the structure to begin with.  If we never assigned to it,
+	   magic will still be zero. */
+	if (!ubbest->ub_magic) {
+		printf("couldn't find a valid ZFS label\n");
+		zfs_unmount(data);
+		free(ubbest);
+		return 0;
+	}
+
+	debug("zfs ubbest %p in label %d\n", ubbest, bestlabel);
+
+	zfs_endian_t ub_endian =
+		zfs_to_cpu64(ubbest->ub_magic, LITTLE_ENDIAN) == UBERBLOCK_MAGIC
+		? LITTLE_ENDIAN : BIG_ENDIAN;
+
+	debug("zfs endian set to %s\n", !ub_endian ? "big" : "little");
+
+	err = zio_read(&ubbest->ub_rootbp, ub_endian, &osp, &ospsize, data);
+
+	if (err) {
+		printf("couldn't zio_read object directory\n");
+		zfs_unmount(data);
+		free(ubbest);
+		return 0;
+	}
+
+	if (ospsize < OBJSET_PHYS_SIZE_V14) {
+		printf("osp too small\n");
+		zfs_unmount(data);
+		free(osp);
+		free(ubbest);
+		return 0;
+	}
+
+	/* Got the MOS. Save it at the memory addr MOS. */
+	memmove(&(data->mos.dn), &((objset_phys_t *) osp)->os_meta_dnode, DNODE_SIZE);
+	data->mos.endian =
+		(zfs_to_cpu64(ubbest->ub_rootbp.blk_prop, ub_endian) >> 63) & 1;
+	memmove(&(data->current_uberblock), ubbest, sizeof(uberblock_t));
+
+	free(osp);
+	free(ubbest);
+
+	return data;
+}
+
+int
+zfs_fetch_nvlist(device_t dev, char **nvlist)
+{
+	struct zfs_data *zfs;
+	int err;
+
+	zfs = zfs_mount(dev);
+	if (!zfs)
+		return ZFS_ERR_BAD_FS;
+	err = int_zfs_fetch_nvlist(zfs, nvlist);
+	zfs_unmount(zfs);
+	return err;
+}
+
+static int
+zfs_label(device_t device, char **label)
+{
+	char *nvlist;
+	int err;
+	struct zfs_data *data;
+
+	data = zfs_mount(device);
+	if (!data)
+		return ZFS_ERR_BAD_FS;
+
+	err = int_zfs_fetch_nvlist(data, &nvlist);
+	if (err) {
+		zfs_unmount(data);
+		return err;
+	}
+
+	*label = zfs_nvlist_lookup_string(nvlist, ZPOOL_CONFIG_POOL_NAME);
+	free(nvlist);
+	zfs_unmount(data);
+	return ZFS_ERR_NONE;
+}
+
+static int
+zfs_uuid(device_t device, char **uuid)
+{
+	struct zfs_data *data;
+
+	data = zfs_mount(device);
+	if (!data)
+		return ZFS_ERR_BAD_FS;
+
+	*uuid = malloc(17); /* %016llx + nil */
+	if (!*uuid)
+		return ZFS_ERR_OUT_OF_MEMORY;
+
+	/* *uuid = xasprintf ("%016llx", (long long unsigned) data->pool_guid);*/
+	snprintf(*uuid, 17, "%016llx", (long long unsigned) data->pool_guid);
+	zfs_unmount(data);
+
+	return ZFS_ERR_NONE;
+}
+
+/*
+ * zfs_open() locates a file in the rootpool by following the
+ * MOS and places the dnode of the file in the memory address DNODE.
+ */
+int
+zfs_open(struct zfs_file *file, const char *fsfilename)
+{
+	struct zfs_data *data;
+	int err;
+	int isfs;
+
+	data = zfs_mount(file->device);
+	if (!data)
+		return ZFS_ERR_BAD_FS;
+
+	err = dnode_get_fullpath(fsfilename, &(data->mdn), 0,
+							 &(data->dnode), &isfs, data);
+	if (err) {
+		zfs_unmount(data);
+		return err;
+	}
+
+	if (isfs) {
+		zfs_unmount(data);
+		printf("Missing @ or / separator\n");
+		return ZFS_ERR_FILE_NOT_FOUND;
+	}
+
+	/* We found the dnode for this file. Verify if it is a plain file. */
+	if (data->dnode.dn.dn_type != DMU_OT_PLAIN_FILE_CONTENTS) {
+		zfs_unmount(data);
+		printf("not a file\n");
+		return ZFS_ERR_BAD_FILE_TYPE;
+	}
+
+	/* get the file size and set the file position to 0 */
+
+	/*
+	 * For DMU_OT_SA we will need to locate the SIZE attribute
+	 * attribute, which could be either in the bonus buffer
+	 * or the "spill" block.
+	 */
+	if (data->dnode.dn.dn_bonustype == DMU_OT_SA) {
+		void *sahdrp;
+		int hdrsize;
+
+		if (data->dnode.dn.dn_bonuslen != 0) {
+			sahdrp = (sa_hdr_phys_t *) DN_BONUS(&data->dnode.dn);
+		} else if (data->dnode.dn.dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
+			blkptr_t *bp = &data->dnode.dn.dn_spill;
+
+			err = zio_read(bp, data->dnode.endian, &sahdrp, NULL, data);
+			if (err)
+				return err;
+		} else {
+			printf("filesystem is corrupt :(\n");
+			return ZFS_ERR_BAD_FS;
+		}
+
+		hdrsize = SA_HDR_SIZE(((sa_hdr_phys_t *) sahdrp));
+		file->size = *(uint64_t *) ((char *) sahdrp + hdrsize + SA_SIZE_OFFSET);
+	} else {
+		file->size = zfs_to_cpu64(((znode_phys_t *) DN_BONUS(&data->dnode.dn))->zp_size, data->dnode.endian);
+	}
+
+	file->data = data;
+	file->offset = 0;
+
+	return ZFS_ERR_NONE;
+}
+
+uint64_t
+zfs_read(zfs_file_t file, char *buf, uint64_t len)
+{
+	struct zfs_data *data = (struct zfs_data *) file->data;
+	int blksz, movesize;
+	uint64_t length;
+	int64_t red;
+	int err;
+
+	if (data->file_buf == NULL) {
+		data->file_buf = malloc(SPA_MAXBLOCKSIZE);
+		if (!data->file_buf)
+			return -1;
+		data->file_start = data->file_end = 0;
+	}
+
+	/*
+	 * If offset is in memory, move it into the buffer provided and return.
+	 */
+	if (file->offset >= data->file_start
+		&& file->offset + len <= data->file_end) {
+		memmove(buf, data->file_buf + file->offset - data->file_start,
+				len);
+		return len;
+	}
+
+	blksz = zfs_to_cpu16(data->dnode.dn.dn_datablkszsec,
+							  data->dnode.endian) << SPA_MINBLOCKSHIFT;
+
+	/*
+	 * Entire Dnode is too big to fit into the space available.	 We
+	 * will need to read it in chunks.	This could be optimized to
+	 * read in as large a chunk as there is space available, but for
+	 * now, this only reads in one data block at a time.
+	 */
+	length = len;
+	red = 0;
+	while (length) {
+		void *t;
+		/*
+		 * Find requested blkid and the offset within that block.
+		 */
+		uint64_t blkid = (file->offset + red) /	 blksz;
+		free(data->file_buf);
+		data->file_buf = 0;
+
+		err = dmu_read(&(data->dnode), blkid, &t,
+					   0, data);
+		data->file_buf = t;
+		if (err)
+			return -1;
+
+		data->file_start = blkid * blksz;
+		data->file_end = data->file_start + blksz;
+
+		movesize = MIN(length, data->file_end - (int) file->offset - red);
+
+		memmove(buf, data->file_buf + file->offset + red
+				- data->file_start, movesize);
+		buf += movesize;
+		length -= movesize;
+		red += movesize;
+	}
+
+	return len;
+}
+
+int
+zfs_close(zfs_file_t file)
+{
+	zfs_unmount((struct zfs_data *) file->data);
+	return ZFS_ERR_NONE;
+}
+
+int
+zfs_getmdnobj(device_t dev, const char *fsfilename,
+				   uint64_t *mdnobj)
+{
+	struct zfs_data *data;
+	int err;
+	int isfs;
+
+	data = zfs_mount(dev);
+	if (!data)
+		return ZFS_ERR_BAD_FS;
+
+	err = dnode_get_fullpath(fsfilename, &(data->mdn), mdnobj,
+							 &(data->dnode), &isfs, data);
+	zfs_unmount(data);
+	return err;
+}
+
+static void
+fill_fs_info(struct zfs_dirhook_info *info,
+			 dnode_end_t mdn, struct zfs_data *data)
+{
+	int err;
+	dnode_end_t dn;
+	uint64_t objnum;
+	uint64_t headobj;
+
+	memset(info, 0, sizeof(*info));
+
+	info->dir = 1;
+
+	if (mdn.dn.dn_type == DMU_OT_DSL_DIR) {
+		headobj = zfs_to_cpu64(((dsl_dir_phys_t *) DN_BONUS(&mdn.dn))->dd_head_dataset_obj, mdn.endian);
+
+		err = dnode_get(&(data->mos), headobj, DMU_OT_DSL_DATASET, &mdn, data);
+		if (err) {
+			printf("zfs failed here 1\n");
+			return;
+		}
+	}
+	make_mdn(&mdn, data);
+	err = dnode_get(&mdn, MASTER_NODE_OBJ, DMU_OT_MASTER_NODE,
+					&dn, data);
+	if (err) {
+		printf("zfs failed here 2\n");
+		return;
+	}
+
+	err = zap_lookup(&dn, ZFS_ROOT_OBJ, &objnum, data);
+	if (err) {
+		printf("zfs failed here 3\n");
+		return;
+	}
+
+	err = dnode_get(&mdn, objnum, 0, &dn, data);
+	if (err) {
+		printf("zfs failed here 4\n");
+		return;
+	}
+
+	info->mtimeset = 1;
+	info->mtime = zfs_to_cpu64(((znode_phys_t *) DN_BONUS(&dn.dn))->zp_mtime[0], dn.endian);
+
+	return;
+}
+
+static int iterate_zap(const char *name, uint64_t val, struct zfs_data *data)
+{
+	struct zfs_dirhook_info info;
+	dnode_end_t dn;
+
+	memset(&info, 0, sizeof(info));
+
+	dnode_get(&(data->mdn), val, 0, &dn, data);
+	info.mtimeset = 1;
+	info.mtime = zfs_to_cpu64(((znode_phys_t *) DN_BONUS(&dn.dn))->zp_mtime[0], dn.endian);
+	info.dir = (dn.dn.dn_type == DMU_OT_DIRECTORY_CONTENTS);
+	debug("zfs type=%d, name=%s\n",
+		  (int)dn.dn.dn_type, (char *)name);
+	if (!data->userhook)
+		return 0;
+	return data->userhook(name, &info);
+}
+
+static int iterate_zap_fs(const char *name, uint64_t val, struct zfs_data *data)
+{
+	struct zfs_dirhook_info info;
+	dnode_end_t mdn;
+	int err;
+	err = dnode_get(&(data->mos), val, 0, &mdn, data);
+	if (err)
+		return 0;
+	if (mdn.dn.dn_type != DMU_OT_DSL_DIR)
+		return 0;
+
+	fill_fs_info(&info, mdn, data);
+
+	if (!data->userhook)
+		return 0;
+	return data->userhook(name, &info);
+}
+
+static int iterate_zap_snap(const char *name, uint64_t val, struct zfs_data *data)
+{
+	struct zfs_dirhook_info info;
+	char *name2;
+	int ret = 0;
+	dnode_end_t mdn;
+	int err;
+
+	err = dnode_get(&(data->mos), val, 0, &mdn, data);
+	if (err)
+		return 0;
+
+	if (mdn.dn.dn_type != DMU_OT_DSL_DATASET)
+		return 0;
+
+	fill_fs_info(&info, mdn, data);
+
+	name2 = malloc(strlen(name) + 2);
+	name2[0] = '@';
+	memcpy(name2 + 1, name, strlen(name) + 1);
+	if (data->userhook)
+		ret = data->userhook(name2, &info);
+	free(name2);
+	return ret;
+}
+
+int
+zfs_ls(device_t device, const char *path,
+	   int (*hook)(const char *, const struct zfs_dirhook_info *))
+{
+	struct zfs_data *data;
+	int err;
+	int isfs;
+#if 0
+	char *label = NULL;
+
+	zfs_label(device, &label);
+	if (label)
+		printf("ZPOOL label '%s'\n",
+			   label);
+#endif
+
+	data = zfs_mount(device);
+	if (!data)
+		return ZFS_ERR_BAD_FS;
+
+	data->userhook = hook;
+
+	err = dnode_get_fullpath(path, &(data->mdn), 0, &(data->dnode), &isfs, data);
+	if (err) {
+		zfs_unmount(data);
+		return err;
+	}
+	if (isfs) {
+		uint64_t childobj, headobj;
+		uint64_t snapobj;
+		dnode_end_t dn;
+		struct zfs_dirhook_info info;
+
+		fill_fs_info(&info, data->dnode, data);
+		hook("@", &info);
+
+		childobj = zfs_to_cpu64(((dsl_dir_phys_t *) DN_BONUS(&data->dnode.dn))->dd_child_dir_zapobj, data->dnode.endian);
+		headobj = zfs_to_cpu64(((dsl_dir_phys_t *) DN_BONUS(&data->dnode.dn))->dd_head_dataset_obj, data->dnode.endian);
+		err = dnode_get(&(data->mos), childobj,
+						DMU_OT_DSL_DIR_CHILD_MAP, &dn, data);
+		if (err) {
+			zfs_unmount(data);
+			return err;
+		}
+
+
+		zap_iterate(&dn, iterate_zap_fs, data);
+
+		err = dnode_get(&(data->mos), headobj, DMU_OT_DSL_DATASET, &dn, data);
+		if (err) {
+			zfs_unmount(data);
+			return err;
+		}
+
+		snapobj = zfs_to_cpu64(((dsl_dataset_phys_t *) DN_BONUS(&dn.dn))->ds_snapnames_zapobj, dn.endian);
+
+		err = dnode_get(&(data->mos), snapobj,
+						DMU_OT_DSL_DS_SNAP_MAP, &dn, data);
+		if (err) {
+			zfs_unmount(data);
+			return err;
+		}
+
+		zap_iterate(&dn, iterate_zap_snap, data);
+	} else {
+		if (data->dnode.dn.dn_type != DMU_OT_DIRECTORY_CONTENTS) {
+			zfs_unmount(data);
+			printf("not a directory\n");
+			return ZFS_ERR_BAD_FILE_TYPE;
+		}
+		zap_iterate(&(data->dnode), iterate_zap, data);
+	}
+	zfs_unmount(data);
+	return ZFS_ERR_NONE;
+}