Index: stand/efi/boot1/zfs_module.c
===================================================================
--- stand/efi/boot1/zfs_module.c
+++ stand/efi/boot1/zfs_module.c
@@ -50,7 +50,7 @@
 }
 
 static int
-vdev_read(vdev_t *vdev, void *priv, off_t off, void *buf, size_t bytes)
+vdev_read(vdev_t *vdev, void *priv, uint64_t off, void *buf, size_t bytes)
 {
 	dev_info_t *devinfo;
 	uint64_t lba;
Index: stand/geli/geliboot.h
===================================================================
--- stand/geli/geliboot.h
+++ stand/geli/geliboot.h
@@ -51,7 +51,7 @@
 struct dsk;
 
 void geli_init(void);
-int geli_taste(int read_func(void *vdev, void *priv, off_t off,
+int geli_taste(int read_func(void *vdev, void *priv, uint64_t off,
     void *buf, size_t bytes), struct dsk *dsk, daddr_t lastsector);
 int is_geli(struct dsk *dsk);
 int geli_read(struct dsk *dsk, off_t offset, u_char *buf, size_t bytes);
Index: stand/geli/geliboot.c
===================================================================
--- stand/geli/geliboot.c
+++ stand/geli/geliboot.c
@@ -151,7 +151,7 @@
  * if it is GELI encrypted
  */
 int
-geli_taste(int read_func(void *vdev, void *priv, off_t off, void *buf,
+geli_taste(int read_func(void *vdev, void *priv, uint64_t off, void *buf,
     size_t bytes), struct dsk *dskp, daddr_t lastsector)
 {
 	struct g_eli_metadata md;
Index: stand/i386/gptboot/gptboot.c
===================================================================
--- stand/i386/gptboot/gptboot.c
+++ stand/i386/gptboot/gptboot.c
@@ -106,7 +106,7 @@
 static int parse_cmds(char *, int *);
 static int dskread(void *, daddr_t, unsigned);
 #ifdef LOADER_GELI_SUPPORT
-static int vdev_read(void *vdev __unused, void *priv, off_t off, void *buf,
+static int vdev_read(void *vdev __unused, void *priv, uint64_t off, void *buf,
 	size_t bytes);
 #endif
 
@@ -614,7 +614,7 @@
  * Implementation the same for both UFS and ZFS
  */
 static int
-vdev_read(void *vdev __unused, void *priv, off_t off, void *buf, size_t bytes)
+vdev_read(void *vdev __unused, void *priv, uint64_t off, void *buf, size_t bytes)
 {
 	char *p;
 	daddr_t lba;
Index: stand/i386/libi386/biosdisk.c
===================================================================
--- stand/i386/libi386/biosdisk.c
+++ stand/i386/libi386/biosdisk.c
@@ -146,7 +146,7 @@
 };
 static enum isgeli geli_status[MAXBDDEV][MAXTBLENTS];
 
-int bios_read(void *, void *, off_t off, void *buf, size_t bytes);
+int bios_read(void *, void *, uint64_t off, void *buf, size_t bytes);
 #endif /* LOADER_GELI_SUPPORT */
 
 struct devsw biosdisk = {
@@ -846,7 +846,7 @@
 {
 #ifdef LOADER_GELI_SUPPORT
 	struct dsk dskp;
-	off_t p_off, diff;
+	uint64_t p_off, diff;
 	daddr_t alignlba;
 	int err, n, alignblks;
 	char *tmpbuf;
@@ -1009,7 +1009,8 @@
 
 #ifdef LOADER_GELI_SUPPORT
 int
-bios_read(void *vdev __unused, void *xpriv, off_t off, void *buf, size_t bytes)
+bios_read(void *vdev __unused, void *xpriv, uint64_t off, void *buf,
+    size_t bytes)
 {
 	struct disk_devdesc dev;
 	struct dsk *priv = xpriv;
Index: stand/i386/zfsboot/zfsboot.c
===================================================================
--- stand/i386/zfsboot/zfsboot.c
+++ stand/i386/zfsboot/zfsboot.c
@@ -138,7 +138,8 @@
  * Read from a dnode (which must be from a ZPL filesystem).
  */
 static int
-zfs_read(spa_t *spa, const dnode_phys_t *dnode, off_t *offp, void *start, size_t size)
+zfs_read(spa_t *spa, const dnode_phys_t *dnode, uint64_t *offp, void *start,
+    size_t size)
 {
 	const znode_phys_t *zp = (const znode_phys_t *) dnode->dn_bonus;
 	size_t n;
@@ -168,11 +169,11 @@
  * buffer pointer crosses a 64k boundary.
  */
 static int
-vdev_read(void *xvdev, void *priv, off_t off, void *buf, size_t bytes)
+vdev_read(void *xvdev, void *priv, uint64_t off, void *buf, size_t bytes)
 {
 	char *p;
 	daddr_t lba, alignlba;
-	off_t diff;
+	uint64_t diff;
 	unsigned int nb, alignnb;
 	struct dsk *dsk = (struct dsk *) priv;
 
@@ -232,14 +233,14 @@
 }
 /* Match the signature exactly due to signature madness */
 static int
-vdev_read2(vdev_t *vdev, void *priv, off_t off, void *buf, size_t bytes)
+vdev_read2(vdev_t *vdev, void *priv, uint64_t off, void *buf, size_t bytes)
 {
 	return vdev_read(vdev, priv, off, buf, bytes);
 }
 
 
 static int
-vdev_write(vdev_t *vdev, void *priv, off_t off, void *buf, size_t bytes)
+vdev_write(vdev_t *vdev, void *priv, uint64_t off, void *buf, size_t bytes)
 {
 	char *p;
 	daddr_t lba;
@@ -268,7 +269,7 @@
 }
 
 static int
-xfsread(const dnode_phys_t *dnode, off_t *offp, void *buf, size_t nbyte)
+xfsread(const dnode_phys_t *dnode, uint64_t *offp, void *buf, size_t nbyte)
 {
     if ((size_t)zfs_read(spa, dnode, offp, buf, nbyte) != nbyte) {
 	printf("Invalid format\n");
@@ -286,7 +287,7 @@
 {
 	blkptr_t bp;
 	char *tmp = zap_scratch;
-	off_t off = offsetof(vdev_label_t, vl_pad2);
+	uint64_t off = offsetof(vdev_label_t, vl_pad2);
 
 	if (size > VDEV_PAD_SIZE)
 		size = VDEV_PAD_SIZE;
@@ -308,7 +309,7 @@
 {
 	char *zeroes = zap_scratch;
 	uint64_t *end;
-	off_t off = offsetof(vdev_label_t, vl_pad2);
+	uint64_t off = offsetof(vdev_label_t, vl_pad2);
 
 	memset(zeroes, 0, VDEV_PAD_SIZE);
 	end = (uint64_t *)(zeroes + VDEV_PAD_SIZE);
@@ -668,7 +669,7 @@
 main(void)
 {
     dnode_phys_t dn;
-    off_t off;
+    uint64_t off;
     struct dsk *dsk;
     int autoboot, i;
     int nextboot;
@@ -891,7 +892,7 @@
     static Elf32_Shdr es[2];
     caddr_t p;
     dnode_phys_t dn;
-    off_t off;
+    uint64_t off;
     uint32_t addr, x;
     int fmt, i, j;
 
Index: stand/zfs/zfs.c
===================================================================
--- stand/zfs/zfs.c
+++ stand/zfs/zfs.c
@@ -359,12 +359,12 @@
 }
 
 static int
-vdev_read(vdev_t *vdev, void *priv, off_t offset, void *buf, size_t bytes)
+vdev_read(vdev_t *vdev, void *priv, uint64_t offset, void *buf, size_t bytes)
 {
 	int fd, ret;
 	size_t res, size, remainder, rb_size, blksz;
 	unsigned secsz;
-	off_t off;
+	uint64_t off;
 	char *bouncebuf, *rb_buf;
 
 	fd = (uintptr_t) priv;
Index: stand/zfs/zfsimpl.c
===================================================================
--- stand/zfs/zfsimpl.c
+++ stand/zfs/zfsimpl.c
@@ -408,7 +408,7 @@
 
 static int
 vdev_read_phys(vdev_t *vdev, const blkptr_t *bp, void *buf,
-    off_t offset, size_t size)
+    uint64_t offset, size_t size)
 {
 	size_t psize;
 	int rc;
@@ -434,7 +434,7 @@
 
 static int
 vdev_disk_read(vdev_t *vdev, const blkptr_t *bp, void *buf,
-    off_t offset, size_t bytes)
+    uint64_t offset, size_t bytes)
 {
 
 	return (vdev_read_phys(vdev, bp, buf,
@@ -444,7 +444,7 @@
 
 static int
 vdev_mirror_read(vdev_t *vdev, const blkptr_t *bp, void *buf,
-    off_t offset, size_t bytes)
+    uint64_t offset, size_t bytes)
 {
 	vdev_t *kid;
 	int rc;
@@ -463,7 +463,7 @@
 
 static int
 vdev_replacing_read(vdev_t *vdev, const blkptr_t *bp, void *buf,
-    off_t offset, size_t bytes)
+    uint64_t offset, size_t bytes)
 {
 	vdev_t *kid;
 
@@ -935,7 +935,7 @@
 	vdev_phys_t *tmp_label;
 	spa_t *spa;
 	vdev_t *vdev, *top_vdev, *pool_vdev;
-	off_t off;
+	uint64_t off;
 	blkptr_t bp;
 	const unsigned char *nvlist = NULL;
 	uint64_t val;
@@ -1253,7 +1253,7 @@
 		const dva_t *dva = &bp->blk_dva[i];
 		vdev_t *vdev;
 		int vdevid;
-		off_t offset;
+		uint64_t offset;
 
 		if (!dva->dva_word[0] && !dva->dva_word[1])
 			continue;
@@ -1300,7 +1300,8 @@
 }
 
 static int
-dnode_read(const spa_t *spa, const dnode_phys_t *dnode, off_t offset, void *buf, size_t buflen)
+dnode_read(const spa_t *spa, const dnode_phys_t *dnode, uint64_t offset,
+    void *buf, size_t buflen)
 {
 	int ibshift = dnode->dn_indblkshift - SPA_BLKPTRSHIFT;
 	int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
@@ -1519,10 +1520,11 @@
 {
 	int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
 	zap_phys_t zh = *(zap_phys_t *) zap_scratch;
+	zap_leaf_chunk_t *zc;
 	fat_zap_t z;
 	uint64_t *ptrtbl;
-	uint64_t hash;
-	int rc;
+	uint64_t hash, off;
+	int shift, h, rc;
 
 	if (zh.zap_magic != ZAP_MAGIC)
 		return (EIO);
@@ -1548,8 +1550,7 @@
 	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;
+	off = ptrtbl[hash >> (64 - zh.zap_ptrtbl.zt_shift)] << zl.l_bs;
 
 	rc = dnode_read(spa, dnode, off, zap_scratch, bsize);
 	if (rc)
@@ -1568,8 +1569,8 @@
 	/*
 	 * 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);
+	shift = 64 - ZAP_LEAF_HASH_SHIFT(&zl) - zl.l_phys->l_hdr.lh_prefix_len;
+	h = (hash >> shift) & ((1 << ZAP_LEAF_HASH_SHIFT(&zl)) - 1);
 	h = zl.l_phys->l_hash[h];
 	if (h == 0xffff)
 		return (ENOENT);
@@ -1675,7 +1676,7 @@
 	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;
+		uint64_t off = (i + 1) << zl.l_bs;
 		char name[256], *p;
 		uint64_t value;
 
@@ -1755,9 +1756,10 @@
 }
 
 static int
-objset_get_dnode(const spa_t *spa, const objset_phys_t *os, uint64_t objnum, dnode_phys_t *dnode)
+objset_get_dnode(const spa_t *spa, const objset_phys_t *os, uint64_t objnum,
+    dnode_phys_t *dnode)
 {
-	off_t offset;
+	uint64_t offset;
 
 	offset = objnum * sizeof(dnode_phys_t);
 	return dnode_read(spa, &os->os_meta_dnode, offset,
@@ -1818,7 +1820,8 @@
 }
 
 static int
-fzap_rlookup(const spa_t *spa, const dnode_phys_t *dnode, char *name, uint64_t value)
+fzap_rlookup(const spa_t *spa, const dnode_phys_t *dnode, char *name,
+    uint64_t value)
 {
 	int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
 	zap_phys_t zh = *(zap_phys_t *) zap_scratch;
@@ -1838,7 +1841,7 @@
 	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;
+		uint64_t off = (i + 1) << zl.l_bs;
 
 		if (dnode_read(spa, dnode, off, zap_scratch, bsize))
 			return (EIO);
@@ -1866,7 +1869,8 @@
 }
 
 static int
-zap_rlookup(const spa_t *spa, const dnode_phys_t *dnode, char *name, uint64_t value)
+zap_rlookup(const spa_t *spa, const dnode_phys_t *dnode, char *name,
+    uint64_t value)
 {
 	int rc;
 	uint64_t zap_type;
Index: sys/cddl/boot/zfs/zfsimpl.h
===================================================================
--- sys/cddl/boot/zfs/zfsimpl.h
+++ sys/cddl/boot/zfs/zfsimpl.h
@@ -1515,9 +1515,9 @@
 struct vdev;
 struct spa;
 typedef int vdev_phys_read_t(struct vdev *vdev, void *priv,
-    off_t offset, void *buf, size_t bytes);
+    uint64_t offset, void *buf, size_t bytes);
 typedef int vdev_read_t(struct vdev *vdev, const blkptr_t *bp,
-    void *buf, off_t offset, size_t bytes);
+    void *buf, uint64_t offset, size_t bytes);
 
 typedef STAILQ_HEAD(vdev_list, vdev) vdev_list_t;
 
Index: sys/cddl/boot/zfs/zfssubr.c
===================================================================
--- sys/cddl/boot/zfs/zfssubr.c
+++ sys/cddl/boot/zfs/zfssubr.c
@@ -1187,8 +1187,8 @@
 }
 
 static raidz_map_t *
-vdev_raidz_map_alloc(void *data, off_t offset, size_t size, uint64_t unit_shift,
-    uint64_t dcols, uint64_t nparity)
+vdev_raidz_map_alloc(void *data, uint64_t offset, size_t size,
+    uint64_t unit_shift, uint64_t dcols, uint64_t nparity)
 {
 	raidz_map_t *rm;
 	uint64_t b = offset >> unit_shift;
@@ -1386,7 +1386,8 @@
  */
 static int
 vdev_raidz_combrec(const spa_t *spa, raidz_map_t *rm, const blkptr_t *bp,
-    void *data, off_t offset, uint64_t bytes, int total_errors, int data_errors)
+    void *data, uint64_t offset, uint64_t bytes, int total_errors,
+    int data_errors)
 {
 	raidz_col_t *rc;
 	void *orig[VDEV_RAIDZ_MAXPARITY];
@@ -1529,7 +1530,7 @@
 
 static int
 vdev_raidz_read(vdev_t *vd, const blkptr_t *bp, void *data,
-    off_t offset, size_t bytes)
+    uint64_t offset, size_t bytes)
 {
 	vdev_t *tvd = vd->v_top;
 	vdev_t *cvd;