diff --git a/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_powerpc.h b/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_powerpc.h
index 2fd806e1a0b5..cf3c712c6af2 100644
--- a/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_powerpc.h
+++ b/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_powerpc.h
@@ -1,88 +1,86 @@
 /*
  * Copyright (C) 2022 Tino Reichardt <milky-zfs@mcmilk.de>
  * 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 AUTHORS 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 AUTHORS 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.
  *
  * $FreeBSD$
  */
 
 /*
  * SIMD support:
  *
  * Following functions should be called to determine whether CPU feature
  * is supported. All functions are usable in kernel and user space.
  * If a SIMD algorithm is using more than one instruction set
  * all relevant feature test functions should be called.
  *
  * Supported features:
  *   zfs_altivec_available()
  *   zfs_vsx_available()
  *   zfs_isa207_available()
  */
 
 #ifndef _FREEBSD_SIMD_POWERPC_H
 #define	_FREEBSD_SIMD_POWERPC_H
 
 #include <sys/types.h>
 #include <sys/cdefs.h>
 
 #include <machine/pcb.h>
 #include <machine/cpu.h>
 
-/* FreeBSD doesn't support floating point on powerpc kernel yet */
 #define	kfpu_allowed()		0
-
 #define	kfpu_initialize(tsk)	do {} while (0)
 #define	kfpu_begin()		do {} while (0)
 #define	kfpu_end()		do {} while (0)
 #define	kfpu_init()		(0)
 #define	kfpu_fini()		do {} while (0)
 
 /*
  * Check if Altivec is available
  */
 static inline boolean_t
 zfs_altivec_available(void)
 {
 	return ((cpu_features & PPC_FEATURE_HAS_ALTIVEC) != 0);
 }
 
 /*
  * Check if VSX is available
  */
 static inline boolean_t
 zfs_vsx_available(void)
 {
 	return ((cpu_features & PPC_FEATURE_HAS_VSX) != 0);
 }
 
 /*
  * Check if POWER ISA 2.07 is available (SHA2)
  */
 static inline boolean_t
 zfs_isa207_available(void)
 {
 	return ((cpu_features2 & PPC_FEATURE2_ARCH_2_07) != 0);
 }
 
 #endif
diff --git a/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_x86.h b/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_x86.h
index 6b4f4011ee48..8e93b558dfe8 100644
--- a/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_x86.h
+++ b/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_x86.h
@@ -1,315 +1,314 @@
 /*
  * Copyright (c) 2020 iXsystems, Inc.
  * 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 AUTHORS 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 AUTHORS 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.
  *
  * $FreeBSD$
  */
 
 #include <sys/types.h>
 #include <sys/cdefs.h>
 #include <sys/proc.h>
 #include <sys/systm.h>
 
 #include <machine/pcb.h>
 #include <x86/x86_var.h>
 #include <x86/specialreg.h>
 
 #define	kfpu_init()		(0)
 #define	kfpu_fini()		do {} while (0)
 #define	kfpu_allowed()		1
 #define	kfpu_initialize(tsk)	do {} while (0)
 
-
 #define	kfpu_begin() {					\
 	if (__predict_false(!is_fpu_kern_thread(0)))		\
 		fpu_kern_enter(curthread, NULL, FPU_KERN_NOCTX);\
 }
 
 #ifndef PCB_FPUNOSAVE
 #define	PCB_FPUNOSAVE	PCB_NPXNOSAVE
 #endif
 
 #define	kfpu_end()	{			\
 	if (__predict_false(curpcb->pcb_flags & PCB_FPUNOSAVE))	\
 		fpu_kern_leave(curthread, NULL);	\
 }
 
 /*
  * Check if OS supports AVX and AVX2 by checking XCR0
  * Only call this function if CPUID indicates that AVX feature is
  * supported by the CPU, otherwise it might be an illegal instruction.
  */
 static inline uint64_t
 xgetbv(uint32_t index)
 {
 	uint32_t eax, edx;
 	/* xgetbv - instruction byte code */
 	__asm__ __volatile__(".byte 0x0f; .byte 0x01; .byte 0xd0"
 	    : "=a" (eax), "=d" (edx)
 	    : "c" (index));
 
 	return ((((uint64_t)edx)<<32) | (uint64_t)eax);
 }
 
 
 /*
  * Detect register set support
  */
 static inline boolean_t
 __simd_state_enabled(const uint64_t state)
 {
 	boolean_t has_osxsave;
 	uint64_t xcr0;
 
 	has_osxsave = (cpu_feature2 & CPUID2_OSXSAVE) != 0;
 
 	if (!has_osxsave)
 		return (B_FALSE);
 
 	xcr0 = xgetbv(0);
 	return ((xcr0 & state) == state);
 }
 
 #define	_XSTATE_SSE_AVX		(0x2 | 0x4)
 #define	_XSTATE_AVX512		(0xE0 | _XSTATE_SSE_AVX)
 
 #define	__ymm_enabled() __simd_state_enabled(_XSTATE_SSE_AVX)
 #define	__zmm_enabled() __simd_state_enabled(_XSTATE_AVX512)
 
 
 /*
  * Check if SSE instruction set is available
  */
 static inline boolean_t
 zfs_sse_available(void)
 {
 	return ((cpu_feature & CPUID_SSE) != 0);
 }
 
 /*
  * Check if SSE2 instruction set is available
  */
 static inline boolean_t
 zfs_sse2_available(void)
 {
 	return ((cpu_feature & CPUID_SSE2) != 0);
 }
 
 /*
  * Check if SSE3 instruction set is available
  */
 static inline boolean_t
 zfs_sse3_available(void)
 {
 	return ((cpu_feature2 & CPUID2_SSE3) != 0);
 }
 
 /*
  * Check if SSSE3 instruction set is available
  */
 static inline boolean_t
 zfs_ssse3_available(void)
 {
 	return ((cpu_feature2 & CPUID2_SSSE3) != 0);
 }
 
 /*
  * Check if SSE4.1 instruction set is available
  */
 static inline boolean_t
 zfs_sse4_1_available(void)
 {
 	return ((cpu_feature2 & CPUID2_SSE41) != 0);
 }
 
 /*
  * Check if SSE4.2 instruction set is available
  */
 static inline boolean_t
 zfs_sse4_2_available(void)
 {
 	return ((cpu_feature2 & CPUID2_SSE42) != 0);
 }
 
 /*
  * Check if AVX instruction set is available
  */
 static inline boolean_t
 zfs_avx_available(void)
 {
 	boolean_t has_avx;
 
 	has_avx = (cpu_feature2 & CPUID2_AVX) != 0;
 
 	return (has_avx && __ymm_enabled());
 }
 
 /*
  * Check if AVX2 instruction set is available
  */
 static inline boolean_t
 zfs_avx2_available(void)
 {
 	boolean_t has_avx2;
 
 	has_avx2 = (cpu_stdext_feature & CPUID_STDEXT_AVX2) != 0;
 
 	return (has_avx2 && __ymm_enabled());
 }
 
 /*
  * Check if SHA_NI instruction set is available
  */
 static inline boolean_t
 zfs_shani_available(void)
 {
 	boolean_t has_shani;
 
 	has_shani = (cpu_stdext_feature & CPUID_STDEXT_SHA) != 0;
 
 	return (has_shani && __ymm_enabled());
 }
 
 /*
  * AVX-512 family of instruction sets:
  *
  * AVX512F	Foundation
  * AVX512CD	Conflict Detection Instructions
  * AVX512ER	Exponential and Reciprocal Instructions
  * AVX512PF	Prefetch Instructions
  *
  * AVX512BW	Byte and Word Instructions
  * AVX512DQ	Double-word and Quadword Instructions
  * AVX512VL	Vector Length Extensions
  *
  * AVX512IFMA	Integer Fused Multiply Add (Not supported by kernel 4.4)
  * AVX512VBMI	Vector Byte Manipulation Instructions
  */
 
 
 /* Check if AVX512F instruction set is available */
 static inline boolean_t
 zfs_avx512f_available(void)
 {
 	boolean_t has_avx512;
 
 	has_avx512 = (cpu_stdext_feature & CPUID_STDEXT_AVX512F) != 0;
 
 	return (has_avx512 && __zmm_enabled());
 }
 
 /* Check if AVX512CD instruction set is available */
 static inline boolean_t
 zfs_avx512cd_available(void)
 {
 	boolean_t has_avx512;
 
 	has_avx512 = (cpu_stdext_feature & CPUID_STDEXT_AVX512F) != 0 &&
 	    (cpu_stdext_feature & CPUID_STDEXT_AVX512CD) != 0;
 
 	return (has_avx512 && __zmm_enabled());
 }
 
 /* Check if AVX512ER instruction set is available */
 static inline boolean_t
 zfs_avx512er_available(void)
 {
 	boolean_t has_avx512;
 
 	has_avx512 = (cpu_stdext_feature & CPUID_STDEXT_AVX512F) != 0 &&
 	    (cpu_stdext_feature & CPUID_STDEXT_AVX512CD) != 0;
 
 	return (has_avx512 && __zmm_enabled());
 }
 
 /* Check if AVX512PF instruction set is available */
 static inline boolean_t
 zfs_avx512pf_available(void)
 {
 	boolean_t has_avx512;
 
 	has_avx512 = (cpu_stdext_feature & CPUID_STDEXT_AVX512F) != 0 &&
 	    (cpu_stdext_feature & CPUID_STDEXT_AVX512PF) != 0;
 
 	return (has_avx512 && __zmm_enabled());
 }
 
 /* Check if AVX512BW instruction set is available */
 static inline boolean_t
 zfs_avx512bw_available(void)
 {
 	boolean_t has_avx512 = B_FALSE;
 
 	has_avx512 = (cpu_stdext_feature & CPUID_STDEXT_AVX512BW) != 0;
 
 	return (has_avx512 && __zmm_enabled());
 }
 
 /* Check if AVX512DQ instruction set is available */
 static inline boolean_t
 zfs_avx512dq_available(void)
 {
 	boolean_t has_avx512;
 
 	has_avx512 = (cpu_stdext_feature & CPUID_STDEXT_AVX512F) != 0 &&
 	    (cpu_stdext_feature & CPUID_STDEXT_AVX512DQ) != 0;
 
 	return (has_avx512 && __zmm_enabled());
 }
 
 /* Check if AVX512VL instruction set is available */
 static inline boolean_t
 zfs_avx512vl_available(void)
 {
 	boolean_t has_avx512;
 
 	has_avx512 = (cpu_stdext_feature & CPUID_STDEXT_AVX512F) != 0 &&
 	    (cpu_stdext_feature & CPUID_STDEXT_AVX512VL) != 0;
 
 	return (has_avx512 && __zmm_enabled());
 }
 
 /* Check if AVX512IFMA instruction set is available */
 static inline boolean_t
 zfs_avx512ifma_available(void)
 {
 	boolean_t has_avx512;
 
 	has_avx512 = (cpu_stdext_feature & CPUID_STDEXT_AVX512F) != 0 &&
 	    (cpu_stdext_feature & CPUID_STDEXT_AVX512IFMA) != 0;
 
 	return (has_avx512 && __zmm_enabled());
 }
 
 /* Check if AVX512VBMI instruction set is available */
 static inline boolean_t
 zfs_avx512vbmi_available(void)
 {
 	boolean_t has_avx512;
 
 	has_avx512 = (cpu_stdext_feature & CPUID_STDEXT_AVX512F) != 0 &&
 	    (cpu_stdext_feature & CPUID_STDEXT_BMI1) != 0;
 
 	return (has_avx512 && __zmm_enabled());
 }
diff --git a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_ctldir.c b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_ctldir.c
index 9e8a4d62f641..4d539461886b 100644
--- a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_ctldir.c
+++ b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_ctldir.c
@@ -1,1379 +1,1379 @@
 /*
  * CDDL HEADER START
  *
  * The contents of this file are subject to the terms of the
  * Common Development and Distribution License (the "License").
  * You may not use this file except in compliance with the License.
  *
  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  * or https://opensource.org/licenses/CDDL-1.0.
  * See the License for the specific language governing permissions
  * and limitations under the License.
  *
  * When distributing Covered Code, include this CDDL HEADER in each
  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  * If applicable, add the following below this CDDL HEADER, with the
  * fields enclosed by brackets "[]" replaced with your own identifying
  * information: Portions Copyright [yyyy] [name of copyright owner]
  *
  * CDDL HEADER END
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
  * Copyright 2015, OmniTI Computer Consulting, Inc. All rights reserved.
  */
 
 /*
  * ZFS control directory (a.k.a. ".zfs")
  *
  * This directory provides a common location for all ZFS meta-objects.
  * Currently, this is only the 'snapshot' directory, but this may expand in the
  * future.  The elements are built using the GFS primitives, as the hierarchy
  * does not actually exist on disk.
  *
  * For 'snapshot', we don't want to have all snapshots always mounted, because
  * this would take up a huge amount of space in /etc/mnttab.  We have three
  * types of objects:
  *
  * 	ctldir ------> snapshotdir -------> snapshot
  *                                             |
  *                                             |
  *                                             V
  *                                         mounted fs
  *
  * The 'snapshot' node contains just enough information to lookup '..' and act
  * as a mountpoint for the snapshot.  Whenever we lookup a specific snapshot, we
  * perform an automount of the underlying filesystem and return the
  * corresponding vnode.
  *
  * All mounts are handled automatically by the kernel, but unmounts are
  * (currently) handled from user land.  The main reason is that there is no
  * reliable way to auto-unmount the filesystem when it's "no longer in use".
  * When the user unmounts a filesystem, we call zfsctl_unmount(), which
  * unmounts any snapshots within the snapshot directory.
  *
  * The '.zfs', '.zfs/snapshot', and all directories created under
  * '.zfs/snapshot' (ie: '.zfs/snapshot/<snapname>') are all GFS nodes and
  * share the same vfs_t as the head filesystem (what '.zfs' lives under).
  *
  * File systems mounted ontop of the GFS nodes '.zfs/snapshot/<snapname>'
  * (ie: snapshots) are ZFS nodes and have their own unique vfs_t.
  * However, vnodes within these mounted on file systems have their v_vfsp
  * fields set to the head filesystem to make NFS happy (see
  * zfsctl_snapdir_lookup()). We VFS_HOLD the head filesystem's vfs_t
  * so that it cannot be freed until all snapshots have been unmounted.
  */
 
 #include <sys/types.h>
 #include <sys/param.h>
 #include <sys/libkern.h>
 #include <sys/dirent.h>
 #include <sys/zfs_context.h>
 #include <sys/zfs_ctldir.h>
 #include <sys/zfs_ioctl.h>
 #include <sys/zfs_vfsops.h>
 #include <sys/namei.h>
 #include <sys/stat.h>
 #include <sys/dmu.h>
 #include <sys/dsl_dataset.h>
 #include <sys/dsl_destroy.h>
 #include <sys/dsl_deleg.h>
 #include <sys/mount.h>
 #include <sys/zap.h>
 #include <sys/sysproto.h>
 
 #include "zfs_namecheck.h"
 
 #include <sys/kernel.h>
 #include <sys/ccompat.h>
 
 /* Common access mode for all virtual directories under the ctldir */
 const uint16_t zfsctl_ctldir_mode = S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP |
     S_IROTH | S_IXOTH;
 
 /*
  * "Synthetic" filesystem implementation.
  */
 
 /*
  * Assert that A implies B.
  */
 #define	KASSERT_IMPLY(A, B, msg)	KASSERT(!(A) || (B), (msg));
 
 static MALLOC_DEFINE(M_SFSNODES, "sfs_nodes", "synthetic-fs nodes");
 
 typedef struct sfs_node {
 	char		sn_name[ZFS_MAX_DATASET_NAME_LEN];
 	uint64_t	sn_parent_id;
 	uint64_t	sn_id;
 } sfs_node_t;
 
 /*
  * Check the parent's ID as well as the node's to account for a chance
  * that IDs originating from different domains (snapshot IDs, artificial
  * IDs, znode IDs) may clash.
  */
 static int
 sfs_compare_ids(struct vnode *vp, void *arg)
 {
 	sfs_node_t *n1 = vp->v_data;
 	sfs_node_t *n2 = arg;
 	bool equal;
 
 	equal = n1->sn_id == n2->sn_id &&
 	    n1->sn_parent_id == n2->sn_parent_id;
 
 	/* Zero means equality. */
 	return (!equal);
 }
 
 static int
 sfs_vnode_get(const struct mount *mp, int flags, uint64_t parent_id,
     uint64_t id, struct vnode **vpp)
 {
 	sfs_node_t search;
 	int err;
 
 	search.sn_id = id;
 	search.sn_parent_id = parent_id;
 	err = vfs_hash_get(mp, (uint32_t)id, flags, curthread, vpp,
 	    sfs_compare_ids, &search);
 	return (err);
 }
 
 static int
 sfs_vnode_insert(struct vnode *vp, int flags, uint64_t parent_id,
     uint64_t id, struct vnode **vpp)
 {
 	int err;
 
 	KASSERT(vp->v_data != NULL, ("sfs_vnode_insert with NULL v_data"));
 	err = vfs_hash_insert(vp, (uint32_t)id, flags, curthread, vpp,
 	    sfs_compare_ids, vp->v_data);
 	return (err);
 }
 
 static void
 sfs_vnode_remove(struct vnode *vp)
 {
 	vfs_hash_remove(vp);
 }
 
 typedef void sfs_vnode_setup_fn(vnode_t *vp, void *arg);
 
 static int
 sfs_vgetx(struct mount *mp, int flags, uint64_t parent_id, uint64_t id,
     const char *tag, struct vop_vector *vops,
     sfs_vnode_setup_fn setup, void *arg,
     struct vnode **vpp)
 {
 	struct vnode *vp;
 	int error;
 
 	error = sfs_vnode_get(mp, flags, parent_id, id, vpp);
 	if (error != 0 || *vpp != NULL) {
 		KASSERT_IMPLY(error == 0, (*vpp)->v_data != NULL,
 		    "sfs vnode with no data");
 		return (error);
 	}
 
 	/* Allocate a new vnode/inode. */
 	error = getnewvnode(tag, mp, vops, &vp);
 	if (error != 0) {
 		*vpp = NULL;
 		return (error);
 	}
 
 	/*
 	 * Exclusively lock the vnode vnode while it's being constructed.
 	 */
 	lockmgr(vp->v_vnlock, LK_EXCLUSIVE, NULL);
 	error = insmntque(vp, mp);
 	if (error != 0) {
 		*vpp = NULL;
 		return (error);
 	}
 
 	setup(vp, arg);
 
 	error = sfs_vnode_insert(vp, flags, parent_id, id, vpp);
 	if (error != 0 || *vpp != NULL) {
 		KASSERT_IMPLY(error == 0, (*vpp)->v_data != NULL,
 		    "sfs vnode with no data");
 		return (error);
 	}
 
 #if __FreeBSD_version >= 1400077
 	vn_set_state(vp, VSTATE_CONSTRUCTED);
 #endif
 
 	*vpp = vp;
 	return (0);
 }
 
 static void
 sfs_print_node(sfs_node_t *node)
 {
 	printf("\tname = %s\n", node->sn_name);
 	printf("\tparent_id = %ju\n", (uintmax_t)node->sn_parent_id);
 	printf("\tid = %ju\n", (uintmax_t)node->sn_id);
 }
 
 static sfs_node_t *
 sfs_alloc_node(size_t size, const char *name, uint64_t parent_id, uint64_t id)
 {
 	struct sfs_node *node;
 
 	KASSERT(strlen(name) < sizeof (node->sn_name),
 	    ("sfs node name is too long"));
 	KASSERT(size >= sizeof (*node), ("sfs node size is too small"));
 	node = malloc(size, M_SFSNODES, M_WAITOK | M_ZERO);
 	strlcpy(node->sn_name, name, sizeof (node->sn_name));
 	node->sn_parent_id = parent_id;
 	node->sn_id = id;
 
 	return (node);
 }
 
 static void
 sfs_destroy_node(sfs_node_t *node)
 {
 	free(node, M_SFSNODES);
 }
 
 static void *
 sfs_reclaim_vnode(vnode_t *vp)
 {
 	void *data;
 
 	sfs_vnode_remove(vp);
 	data = vp->v_data;
 	vp->v_data = NULL;
 	return (data);
 }
 
 static int
 sfs_readdir_common(uint64_t parent_id, uint64_t id, struct vop_readdir_args *ap,
     zfs_uio_t *uio, off_t *offp)
 {
 	struct dirent entry;
 	int error;
 
 	/* Reset ncookies for subsequent use of vfs_read_dirent. */
 	if (ap->a_ncookies != NULL)
 		*ap->a_ncookies = 0;
 
 	if (zfs_uio_resid(uio) < sizeof (entry))
 		return (SET_ERROR(EINVAL));
 
 	if (zfs_uio_offset(uio) < 0)
 		return (SET_ERROR(EINVAL));
 	if (zfs_uio_offset(uio) == 0) {
 		entry.d_fileno = id;
 		entry.d_type = DT_DIR;
 		entry.d_name[0] = '.';
 		entry.d_name[1] = '\0';
 		entry.d_namlen = 1;
 		entry.d_reclen = sizeof (entry);
 		error = vfs_read_dirent(ap, &entry, zfs_uio_offset(uio));
 		if (error != 0)
 			return (SET_ERROR(error));
 	}
 
 	if (zfs_uio_offset(uio) < sizeof (entry))
 		return (SET_ERROR(EINVAL));
 	if (zfs_uio_offset(uio) == sizeof (entry)) {
 		entry.d_fileno = parent_id;
 		entry.d_type = DT_DIR;
 		entry.d_name[0] = '.';
 		entry.d_name[1] = '.';
 		entry.d_name[2] = '\0';
 		entry.d_namlen = 2;
 		entry.d_reclen = sizeof (entry);
 		error = vfs_read_dirent(ap, &entry, zfs_uio_offset(uio));
 		if (error != 0)
 			return (SET_ERROR(error));
 	}
 
 	if (offp != NULL)
 		*offp = 2 * sizeof (entry);
 	return (0);
 }
 
 
 /*
  * .zfs inode namespace
  *
  * We need to generate unique inode numbers for all files and directories
  * within the .zfs pseudo-filesystem.  We use the following scheme:
  *
  * 	ENTRY			ZFSCTL_INODE
  * 	.zfs			1
  * 	.zfs/snapshot		2
  * 	.zfs/snapshot/<snap>	objectid(snap)
  */
 #define	ZFSCTL_INO_SNAP(id)	(id)
 
 static struct vop_vector zfsctl_ops_root;
 static struct vop_vector zfsctl_ops_snapdir;
 static struct vop_vector zfsctl_ops_snapshot;
 
 void
 zfsctl_init(void)
 {
 }
 
 void
 zfsctl_fini(void)
 {
 }
 
 boolean_t
 zfsctl_is_node(vnode_t *vp)
 {
 	return (vn_matchops(vp, zfsctl_ops_root) ||
 	    vn_matchops(vp, zfsctl_ops_snapdir) ||
 	    vn_matchops(vp, zfsctl_ops_snapshot));
 
 }
 
 typedef struct zfsctl_root {
 	sfs_node_t	node;
 	sfs_node_t	*snapdir;
 	timestruc_t	cmtime;
 } zfsctl_root_t;
 
 
 /*
  * Create the '.zfs' directory.
  */
 void
 zfsctl_create(zfsvfs_t *zfsvfs)
 {
 	zfsctl_root_t *dot_zfs;
 	sfs_node_t *snapdir;
 	vnode_t *rvp;
 	uint64_t crtime[2];
 
 	ASSERT3P(zfsvfs->z_ctldir, ==, NULL);
 
 	snapdir = sfs_alloc_node(sizeof (*snapdir), "snapshot", ZFSCTL_INO_ROOT,
 	    ZFSCTL_INO_SNAPDIR);
 	dot_zfs = (zfsctl_root_t *)sfs_alloc_node(sizeof (*dot_zfs), ".zfs", 0,
 	    ZFSCTL_INO_ROOT);
 	dot_zfs->snapdir = snapdir;
 
 	VERIFY0(VFS_ROOT(zfsvfs->z_vfs, LK_EXCLUSIVE, &rvp));
 	VERIFY0(sa_lookup(VTOZ(rvp)->z_sa_hdl, SA_ZPL_CRTIME(zfsvfs),
 	    &crtime, sizeof (crtime)));
 	ZFS_TIME_DECODE(&dot_zfs->cmtime, crtime);
 	vput(rvp);
 
 	zfsvfs->z_ctldir = dot_zfs;
 }
 
 /*
  * Destroy the '.zfs' directory.  Only called when the filesystem is unmounted.
  * The nodes must not have any associated vnodes by now as they should be
  * vflush-ed.
  */
 void
 zfsctl_destroy(zfsvfs_t *zfsvfs)
 {
 	sfs_destroy_node(zfsvfs->z_ctldir->snapdir);
 	sfs_destroy_node((sfs_node_t *)zfsvfs->z_ctldir);
 	zfsvfs->z_ctldir = NULL;
 }
 
 static int
 zfsctl_fs_root_vnode(struct mount *mp, void *arg __unused, int flags,
     struct vnode **vpp)
 {
 	return (VFS_ROOT(mp, flags, vpp));
 }
 
 static void
 zfsctl_common_vnode_setup(vnode_t *vp, void *arg)
 {
 	ASSERT_VOP_ELOCKED(vp, __func__);
 
 	/* We support shared locking. */
 	VN_LOCK_ASHARE(vp);
 	vp->v_type = VDIR;
 	vp->v_data = arg;
 }
 
 static int
 zfsctl_root_vnode(struct mount *mp, void *arg __unused, int flags,
     struct vnode **vpp)
 {
 	void *node;
 	int err;
 
 	node = ((zfsvfs_t *)mp->mnt_data)->z_ctldir;
 	err = sfs_vgetx(mp, flags, 0, ZFSCTL_INO_ROOT, "zfs", &zfsctl_ops_root,
 	    zfsctl_common_vnode_setup, node, vpp);
 	return (err);
 }
 
 static int
 zfsctl_snapdir_vnode(struct mount *mp, void *arg __unused, int flags,
     struct vnode **vpp)
 {
 	void *node;
 	int err;
 
 	node = ((zfsvfs_t *)mp->mnt_data)->z_ctldir->snapdir;
 	err = sfs_vgetx(mp, flags, ZFSCTL_INO_ROOT, ZFSCTL_INO_SNAPDIR, "zfs",
 	    &zfsctl_ops_snapdir, zfsctl_common_vnode_setup, node, vpp);
 	return (err);
 }
 
 /*
  * Given a root znode, retrieve the associated .zfs directory.
  * Add a hold to the vnode and return it.
  */
 int
 zfsctl_root(zfsvfs_t *zfsvfs, int flags, vnode_t **vpp)
 {
 	int error;
 
 	error = zfsctl_root_vnode(zfsvfs->z_vfs, NULL, flags, vpp);
 	return (error);
 }
 
 /*
  * Common open routine.  Disallow any write access.
  */
 static int
 zfsctl_common_open(struct vop_open_args *ap)
 {
 	int flags = ap->a_mode;
 
 	if (flags & FWRITE)
 		return (SET_ERROR(EACCES));
 
 	return (0);
 }
 
 /*
  * Common close routine.  Nothing to do here.
  */
 static int
 zfsctl_common_close(struct vop_close_args *ap)
 {
 	(void) ap;
 	return (0);
 }
 
 /*
  * Common access routine.  Disallow writes.
  */
 static int
 zfsctl_common_access(struct vop_access_args *ap)
 {
 	accmode_t accmode = ap->a_accmode;
 
 	if (accmode & VWRITE)
 		return (SET_ERROR(EACCES));
 	return (0);
 }
 
 /*
  * Common getattr function.  Fill in basic information.
  */
 static void
 zfsctl_common_getattr(vnode_t *vp, vattr_t *vap)
 {
 	timestruc_t	now;
 	sfs_node_t *node;
 
 	node = vp->v_data;
 
 	vap->va_uid = 0;
 	vap->va_gid = 0;
 	vap->va_rdev = 0;
 	/*
 	 * We are a purely virtual object, so we have no
 	 * blocksize or allocated blocks.
 	 */
 	vap->va_blksize = 0;
 	vap->va_nblocks = 0;
 	vap->va_gen = 0;
 	vn_fsid(vp, vap);
 	vap->va_mode = zfsctl_ctldir_mode;
 	vap->va_type = VDIR;
 	/*
 	 * We live in the now (for atime).
 	 */
 	gethrestime(&now);
 	vap->va_atime = now;
 	/* FreeBSD: Reset chflags(2) flags. */
 	vap->va_flags = 0;
 
 	vap->va_nodeid = node->sn_id;
 
 	/* At least '.' and '..'. */
 	vap->va_nlink = 2;
 }
 
 #ifndef _OPENSOLARIS_SYS_VNODE_H_
 struct vop_fid_args {
 	struct vnode *a_vp;
 	struct fid *a_fid;
 };
 #endif
 
 static int
 zfsctl_common_fid(struct vop_fid_args *ap)
 {
 	vnode_t		*vp = ap->a_vp;
 	fid_t		*fidp = (void *)ap->a_fid;
 	sfs_node_t	*node = vp->v_data;
 	uint64_t	object = node->sn_id;
 	zfid_short_t	*zfid;
 	int		i;
 
 	zfid = (zfid_short_t *)fidp;
 	zfid->zf_len = SHORT_FID_LEN;
 
 	for (i = 0; i < sizeof (zfid->zf_object); i++)
 		zfid->zf_object[i] = (uint8_t)(object >> (8 * i));
 
 	/* .zfs nodes always have a generation number of 0 */
 	for (i = 0; i < sizeof (zfid->zf_gen); i++)
 		zfid->zf_gen[i] = 0;
 
 	return (0);
 }
 
 #ifndef _SYS_SYSPROTO_H_
 struct vop_reclaim_args {
 	struct vnode *a_vp;
 	struct thread *a_td;
 };
 #endif
 
 static int
 zfsctl_common_reclaim(struct vop_reclaim_args *ap)
 {
 	vnode_t *vp = ap->a_vp;
 
 	(void) sfs_reclaim_vnode(vp);
 	return (0);
 }
 
 #ifndef _SYS_SYSPROTO_H_
 struct vop_print_args {
 	struct vnode *a_vp;
 };
 #endif
 
 static int
 zfsctl_common_print(struct vop_print_args *ap)
 {
 	sfs_print_node(ap->a_vp->v_data);
 	return (0);
 }
 
 #ifndef _SYS_SYSPROTO_H_
 struct vop_getattr_args {
 	struct vnode *a_vp;
 	struct vattr *a_vap;
 	struct ucred *a_cred;
 };
 #endif
 
 /*
  * Get root directory attributes.
  */
 static int
 zfsctl_root_getattr(struct vop_getattr_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct vattr *vap = ap->a_vap;
 	zfsctl_root_t *node = vp->v_data;
 
 	zfsctl_common_getattr(vp, vap);
 	vap->va_ctime = node->cmtime;
 	vap->va_mtime = vap->va_ctime;
 	vap->va_birthtime = vap->va_ctime;
 	vap->va_nlink += 1; /* snapdir */
 	vap->va_size = vap->va_nlink;
 	return (0);
 }
 
 /*
  * When we lookup "." we still can be asked to lock it
  * differently, can't we?
  */
 static int
 zfsctl_relock_dot(vnode_t *dvp, int ltype)
 {
 	vref(dvp);
 	if (ltype != VOP_ISLOCKED(dvp)) {
 		if (ltype == LK_EXCLUSIVE)
 			vn_lock(dvp, LK_UPGRADE | LK_RETRY);
 		else /* if (ltype == LK_SHARED) */
 			vn_lock(dvp, LK_DOWNGRADE | LK_RETRY);
 
 		/* Relock for the "." case may left us with reclaimed vnode. */
 		if (VN_IS_DOOMED(dvp)) {
 			vrele(dvp);
 			return (SET_ERROR(ENOENT));
 		}
 	}
 	return (0);
 }
 
 /*
  * Special case the handling of "..".
  */
 static int
 zfsctl_root_lookup(struct vop_lookup_args *ap)
 {
 	struct componentname *cnp = ap->a_cnp;
 	vnode_t *dvp = ap->a_dvp;
 	vnode_t **vpp = ap->a_vpp;
 	int flags = ap->a_cnp->cn_flags;
 	int lkflags = ap->a_cnp->cn_lkflags;
 	int nameiop = ap->a_cnp->cn_nameiop;
 	int err;
 
 	ASSERT3S(dvp->v_type, ==, VDIR);
 
 	if ((flags & ISLASTCN) != 0 && nameiop != LOOKUP)
 		return (SET_ERROR(ENOTSUP));
 
 	if (cnp->cn_namelen == 1 && *cnp->cn_nameptr == '.') {
 		err = zfsctl_relock_dot(dvp, lkflags & LK_TYPE_MASK);
 		if (err == 0)
 			*vpp = dvp;
 	} else if ((flags & ISDOTDOT) != 0) {
 		err = vn_vget_ino_gen(dvp, zfsctl_fs_root_vnode, NULL,
 		    lkflags, vpp);
 	} else if (strncmp(cnp->cn_nameptr, "snapshot", cnp->cn_namelen) == 0) {
 		err = zfsctl_snapdir_vnode(dvp->v_mount, NULL, lkflags, vpp);
 	} else {
 		err = SET_ERROR(ENOENT);
 	}
 	if (err != 0)
 		*vpp = NULL;
 	return (err);
 }
 
 static int
 zfsctl_root_readdir(struct vop_readdir_args *ap)
 {
 	struct dirent entry;
 	vnode_t *vp = ap->a_vp;
 	zfsvfs_t *zfsvfs = vp->v_vfsp->vfs_data;
 	zfsctl_root_t *node = vp->v_data;
 	zfs_uio_t uio;
 	int *eofp = ap->a_eofflag;
 	off_t dots_offset;
 	int error;
 
 	zfs_uio_init(&uio, ap->a_uio);
 
 	ASSERT3S(vp->v_type, ==, VDIR);
 
 	/*
 	 * FIXME: this routine only ever emits 3 entries and does not tolerate
 	 * being called with a buffer too small to handle all of them.
 	 *
 	 * The check below facilitates the idiom of repeating calls until the
 	 * count to return is 0.
 	 */
-	if (zfs_uio_offset(&uio) == 3 * sizeof(entry)) {
+	if (zfs_uio_offset(&uio) == 3 * sizeof (entry)) {
 		return (0);
 	}
 
 	error = sfs_readdir_common(zfsvfs->z_root, ZFSCTL_INO_ROOT, ap, &uio,
 	    &dots_offset);
 	if (error != 0) {
 		if (error == ENAMETOOLONG) /* ran out of destination space */
 			error = 0;
 		return (error);
 	}
 	if (zfs_uio_offset(&uio) != dots_offset)
 		return (SET_ERROR(EINVAL));
 
 	_Static_assert(sizeof (node->snapdir->sn_name) <= sizeof (entry.d_name),
 	    "node->snapdir->sn_name too big for entry.d_name");
 	entry.d_fileno = node->snapdir->sn_id;
 	entry.d_type = DT_DIR;
 	strcpy(entry.d_name, node->snapdir->sn_name);
 	entry.d_namlen = strlen(entry.d_name);
 	entry.d_reclen = sizeof (entry);
 	error = vfs_read_dirent(ap, &entry, zfs_uio_offset(&uio));
 	if (error != 0) {
 		if (error == ENAMETOOLONG)
 			error = 0;
 		return (SET_ERROR(error));
 	}
 	if (eofp != NULL)
 		*eofp = 1;
 	return (0);
 }
 
 static int
 zfsctl_root_vptocnp(struct vop_vptocnp_args *ap)
 {
 	static const char dotzfs_name[4] = ".zfs";
 	vnode_t *dvp;
 	int error;
 
 	if (*ap->a_buflen < sizeof (dotzfs_name))
 		return (SET_ERROR(ENOMEM));
 
 	error = vn_vget_ino_gen(ap->a_vp, zfsctl_fs_root_vnode, NULL,
 	    LK_SHARED, &dvp);
 	if (error != 0)
 		return (SET_ERROR(error));
 
 	VOP_UNLOCK(dvp);
 	*ap->a_vpp = dvp;
 	*ap->a_buflen -= sizeof (dotzfs_name);
 	memcpy(ap->a_buf + *ap->a_buflen, dotzfs_name, sizeof (dotzfs_name));
 	return (0);
 }
 
 static int
 zfsctl_common_pathconf(struct vop_pathconf_args *ap)
 {
 	/*
 	 * We care about ACL variables so that user land utilities like ls
 	 * can display them correctly.  Since the ctldir's st_dev is set to be
 	 * the same as the parent dataset, we must support all variables that
 	 * it supports.
 	 */
 	switch (ap->a_name) {
 	case _PC_LINK_MAX:
 		*ap->a_retval = MIN(LONG_MAX, ZFS_LINK_MAX);
 		return (0);
 
 	case _PC_FILESIZEBITS:
 		*ap->a_retval = 64;
 		return (0);
 
 	case _PC_MIN_HOLE_SIZE:
 		*ap->a_retval = (int)SPA_MINBLOCKSIZE;
 		return (0);
 
 	case _PC_ACL_EXTENDED:
 		*ap->a_retval = 0;
 		return (0);
 
 	case _PC_ACL_NFS4:
 		*ap->a_retval = 1;
 		return (0);
 
 	case _PC_ACL_PATH_MAX:
 		*ap->a_retval = ACL_MAX_ENTRIES;
 		return (0);
 
 	case _PC_NAME_MAX:
 		*ap->a_retval = NAME_MAX;
 		return (0);
 
 	default:
 		return (vop_stdpathconf(ap));
 	}
 }
 
 /*
  * Returns a trivial ACL
  */
 static int
 zfsctl_common_getacl(struct vop_getacl_args *ap)
 {
 	int i;
 
 	if (ap->a_type != ACL_TYPE_NFS4)
 		return (EINVAL);
 
 	acl_nfs4_sync_acl_from_mode(ap->a_aclp, zfsctl_ctldir_mode, 0);
 	/*
 	 * acl_nfs4_sync_acl_from_mode assumes that the owner can always modify
 	 * attributes.  That is not the case for the ctldir, so we must clear
 	 * those bits.  We also must clear ACL_READ_NAMED_ATTRS, because xattrs
 	 * aren't supported by the ctldir.
 	 */
 	for (i = 0; i < ap->a_aclp->acl_cnt; i++) {
 		struct acl_entry *entry;
 		entry = &(ap->a_aclp->acl_entry[i]);
 		entry->ae_perm &= ~(ACL_WRITE_ACL | ACL_WRITE_OWNER |
 		    ACL_WRITE_ATTRIBUTES | ACL_WRITE_NAMED_ATTRS |
 		    ACL_READ_NAMED_ATTRS);
 	}
 
 	return (0);
 }
 
 static struct vop_vector zfsctl_ops_root = {
 	.vop_default =	&default_vnodeops,
 	.vop_fplookup_vexec = VOP_EAGAIN,
 	.vop_fplookup_symlink = VOP_EAGAIN,
 	.vop_open =	zfsctl_common_open,
 	.vop_close =	zfsctl_common_close,
 	.vop_ioctl =	VOP_EINVAL,
 	.vop_getattr =	zfsctl_root_getattr,
 	.vop_access =	zfsctl_common_access,
 	.vop_readdir =	zfsctl_root_readdir,
 	.vop_lookup =	zfsctl_root_lookup,
 	.vop_inactive =	VOP_NULL,
 	.vop_reclaim =	zfsctl_common_reclaim,
 	.vop_fid =	zfsctl_common_fid,
 	.vop_print =	zfsctl_common_print,
 	.vop_vptocnp =	zfsctl_root_vptocnp,
 	.vop_pathconf =	zfsctl_common_pathconf,
 	.vop_getacl =	zfsctl_common_getacl,
 #if __FreeBSD_version >= 1400043
 	.vop_add_writecount =	vop_stdadd_writecount_nomsync,
 #endif
 };
 VFS_VOP_VECTOR_REGISTER(zfsctl_ops_root);
 
 static int
 zfsctl_snapshot_zname(vnode_t *vp, const char *name, int len, char *zname)
 {
 	objset_t *os = ((zfsvfs_t *)((vp)->v_vfsp->vfs_data))->z_os;
 
 	dmu_objset_name(os, zname);
 	if (strlen(zname) + 1 + strlen(name) >= len)
 		return (SET_ERROR(ENAMETOOLONG));
 	(void) strcat(zname, "@");
 	(void) strcat(zname, name);
 	return (0);
 }
 
 static int
 zfsctl_snapshot_lookup(vnode_t *vp, const char *name, uint64_t *id)
 {
 	objset_t *os = ((zfsvfs_t *)((vp)->v_vfsp->vfs_data))->z_os;
 	int err;
 
 	err = dsl_dataset_snap_lookup(dmu_objset_ds(os), name, id);
 	return (err);
 }
 
 /*
  * Given a vnode get a root vnode of a filesystem mounted on top of
  * the vnode, if any.  The root vnode is referenced and locked.
  * If no filesystem is mounted then the orinal vnode remains referenced
  * and locked.  If any error happens the orinal vnode is unlocked and
  * released.
  */
 static int
 zfsctl_mounted_here(vnode_t **vpp, int flags)
 {
 	struct mount *mp;
 	int err;
 
 	ASSERT_VOP_LOCKED(*vpp, __func__);
 	ASSERT3S((*vpp)->v_type, ==, VDIR);
 
 	if ((mp = (*vpp)->v_mountedhere) != NULL) {
 		err = vfs_busy(mp, 0);
 		KASSERT(err == 0, ("vfs_busy(mp, 0) failed with %d", err));
 		KASSERT(vrefcnt(*vpp) > 1, ("unreferenced mountpoint"));
 		vput(*vpp);
 		err = VFS_ROOT(mp, flags, vpp);
 		vfs_unbusy(mp);
 		return (err);
 	}
 	return (EJUSTRETURN);
 }
 
 typedef struct {
 	const char *snap_name;
 	uint64_t    snap_id;
 } snapshot_setup_arg_t;
 
 static void
 zfsctl_snapshot_vnode_setup(vnode_t *vp, void *arg)
 {
 	snapshot_setup_arg_t *ssa = arg;
 	sfs_node_t *node;
 
 	ASSERT_VOP_ELOCKED(vp, __func__);
 
 	node = sfs_alloc_node(sizeof (sfs_node_t),
 	    ssa->snap_name, ZFSCTL_INO_SNAPDIR, ssa->snap_id);
 	zfsctl_common_vnode_setup(vp, node);
 
 	/* We have to support recursive locking. */
 	VN_LOCK_AREC(vp);
 }
 
 /*
  * Lookup entry point for the 'snapshot' directory.  Try to open the
  * snapshot if it exist, creating the pseudo filesystem vnode as necessary.
  * Perform a mount of the associated dataset on top of the vnode.
  * There are four possibilities:
  * - the snapshot node and vnode do not exist
  * - the snapshot vnode is covered by the mounted snapshot
  * - the snapshot vnode is not covered yet, the mount operation is in progress
  * - the snapshot vnode is not covered, because the snapshot has been unmounted
  * The last two states are transient and should be relatively short-lived.
  */
 static int
 zfsctl_snapdir_lookup(struct vop_lookup_args *ap)
 {
 	vnode_t *dvp = ap->a_dvp;
 	vnode_t **vpp = ap->a_vpp;
 	struct componentname *cnp = ap->a_cnp;
 	char name[NAME_MAX + 1];
 	char fullname[ZFS_MAX_DATASET_NAME_LEN];
 	char *mountpoint;
 	size_t mountpoint_len;
 	zfsvfs_t *zfsvfs = dvp->v_vfsp->vfs_data;
 	uint64_t snap_id;
 	int nameiop = cnp->cn_nameiop;
 	int lkflags = cnp->cn_lkflags;
 	int flags = cnp->cn_flags;
 	int err;
 
 	ASSERT3S(dvp->v_type, ==, VDIR);
 
 	if ((flags & ISLASTCN) != 0 && nameiop != LOOKUP)
 		return (SET_ERROR(ENOTSUP));
 
 	if (cnp->cn_namelen == 1 && *cnp->cn_nameptr == '.') {
 		err = zfsctl_relock_dot(dvp, lkflags & LK_TYPE_MASK);
 		if (err == 0)
 			*vpp = dvp;
 		return (err);
 	}
 	if (flags & ISDOTDOT) {
 		err = vn_vget_ino_gen(dvp, zfsctl_root_vnode, NULL, lkflags,
 		    vpp);
 		return (err);
 	}
 
 	if (cnp->cn_namelen >= sizeof (name))
 		return (SET_ERROR(ENAMETOOLONG));
 
 	strlcpy(name, ap->a_cnp->cn_nameptr, ap->a_cnp->cn_namelen + 1);
 	err = zfsctl_snapshot_lookup(dvp, name, &snap_id);
 	if (err != 0)
 		return (SET_ERROR(ENOENT));
 
 	for (;;) {
 		snapshot_setup_arg_t ssa;
 
 		ssa.snap_name = name;
 		ssa.snap_id = snap_id;
 		err = sfs_vgetx(dvp->v_mount, LK_SHARED, ZFSCTL_INO_SNAPDIR,
 		    snap_id, "zfs", &zfsctl_ops_snapshot,
 		    zfsctl_snapshot_vnode_setup, &ssa, vpp);
 		if (err != 0)
 			return (err);
 
 		/* Check if a new vnode has just been created. */
 		if (VOP_ISLOCKED(*vpp) == LK_EXCLUSIVE)
 			break;
 
 		/*
 		 * Check if a snapshot is already mounted on top of the vnode.
 		 */
 		err = zfsctl_mounted_here(vpp, lkflags);
 		if (err != EJUSTRETURN)
 			return (err);
 
 		/*
 		 * If the vnode is not covered, then either the mount operation
 		 * is in progress or the snapshot has already been unmounted
 		 * but the vnode hasn't been inactivated and reclaimed yet.
 		 * We can try to re-use the vnode in the latter case.
 		 */
 		VI_LOCK(*vpp);
 		if (((*vpp)->v_iflag & VI_MOUNT) == 0) {
 			VI_UNLOCK(*vpp);
 			/*
 			 * Upgrade to exclusive lock in order to:
 			 * - avoid race conditions
 			 * - satisfy the contract of mount_snapshot()
 			 */
 			err = VOP_LOCK(*vpp, LK_TRYUPGRADE);
 			if (err == 0)
 				break;
 		} else {
 			VI_UNLOCK(*vpp);
 		}
 
 		/*
 		 * In this state we can loop on uncontested locks and starve
 		 * the thread doing the lengthy, non-trivial mount operation.
 		 * So, yield to prevent that from happening.
 		 */
 		vput(*vpp);
 		kern_yield(PRI_USER);
 	}
 
 	VERIFY0(zfsctl_snapshot_zname(dvp, name, sizeof (fullname), fullname));
 
 	mountpoint_len = strlen(dvp->v_vfsp->mnt_stat.f_mntonname) +
 	    strlen("/" ZFS_CTLDIR_NAME "/snapshot/") + strlen(name) + 1;
 	mountpoint = kmem_alloc(mountpoint_len, KM_SLEEP);
 	(void) snprintf(mountpoint, mountpoint_len,
 	    "%s/" ZFS_CTLDIR_NAME "/snapshot/%s",
 	    dvp->v_vfsp->mnt_stat.f_mntonname, name);
 
 	err = mount_snapshot(curthread, vpp, "zfs", mountpoint, fullname, 0,
 	    dvp->v_vfsp);
 	kmem_free(mountpoint, mountpoint_len);
 	if (err == 0) {
 		/*
 		 * Fix up the root vnode mounted on .zfs/snapshot/<snapname>.
 		 *
 		 * This is where we lie about our v_vfsp in order to
 		 * make .zfs/snapshot/<snapname> accessible over NFS
 		 * without requiring manual mounts of <snapname>.
 		 */
 		ASSERT3P(VTOZ(*vpp)->z_zfsvfs, !=, zfsvfs);
 		VTOZ(*vpp)->z_zfsvfs->z_parent = zfsvfs;
 
 		/* Clear the root flag (set via VFS_ROOT) as well. */
 		(*vpp)->v_vflag &= ~VV_ROOT;
 	}
 
 	if (err != 0)
 		*vpp = NULL;
 	return (err);
 }
 
 static int
 zfsctl_snapdir_readdir(struct vop_readdir_args *ap)
 {
 	char snapname[ZFS_MAX_DATASET_NAME_LEN];
 	struct dirent entry;
 	vnode_t *vp = ap->a_vp;
 	zfsvfs_t *zfsvfs = vp->v_vfsp->vfs_data;
 	zfs_uio_t uio;
 	int *eofp = ap->a_eofflag;
 	off_t dots_offset;
 	int error;
 
 	zfs_uio_init(&uio, ap->a_uio);
 
 	ASSERT3S(vp->v_type, ==, VDIR);
 
 	error = sfs_readdir_common(ZFSCTL_INO_ROOT, ZFSCTL_INO_SNAPDIR, ap,
 	    &uio, &dots_offset);
 	if (error != 0) {
 		if (error == ENAMETOOLONG) /* ran out of destination space */
 			error = 0;
 		return (error);
 	}
 
 	if ((error = zfs_enter(zfsvfs, FTAG)) != 0)
 		return (error);
 	for (;;) {
 		uint64_t cookie;
 		uint64_t id;
 
 		cookie = zfs_uio_offset(&uio) - dots_offset;
 
 		dsl_pool_config_enter(dmu_objset_pool(zfsvfs->z_os), FTAG);
 		error = dmu_snapshot_list_next(zfsvfs->z_os, sizeof (snapname),
 		    snapname, &id, &cookie, NULL);
 		dsl_pool_config_exit(dmu_objset_pool(zfsvfs->z_os), FTAG);
 		if (error != 0) {
 			if (error == ENOENT) {
 				if (eofp != NULL)
 					*eofp = 1;
 				error = 0;
 			}
 			zfs_exit(zfsvfs, FTAG);
 			return (error);
 		}
 
 		entry.d_fileno = id;
 		entry.d_type = DT_DIR;
 		strcpy(entry.d_name, snapname);
 		entry.d_namlen = strlen(entry.d_name);
 		entry.d_reclen = sizeof (entry);
 		error = vfs_read_dirent(ap, &entry, zfs_uio_offset(&uio));
 		if (error != 0) {
 			if (error == ENAMETOOLONG)
 				error = 0;
 			zfs_exit(zfsvfs, FTAG);
 			return (SET_ERROR(error));
 		}
 		zfs_uio_setoffset(&uio, cookie + dots_offset);
 	}
 	__builtin_unreachable();
 }
 
 static int
 zfsctl_snapdir_getattr(struct vop_getattr_args *ap)
 {
 	vnode_t *vp = ap->a_vp;
 	vattr_t *vap = ap->a_vap;
 	zfsvfs_t *zfsvfs = vp->v_vfsp->vfs_data;
 	dsl_dataset_t *ds;
 	uint64_t snap_count;
 	int err;
 
 	if ((err = zfs_enter(zfsvfs, FTAG)) != 0)
 		return (err);
 	ds = dmu_objset_ds(zfsvfs->z_os);
 	zfsctl_common_getattr(vp, vap);
 	vap->va_ctime = dmu_objset_snap_cmtime(zfsvfs->z_os);
 	vap->va_mtime = vap->va_ctime;
 	vap->va_birthtime = vap->va_ctime;
 	if (dsl_dataset_phys(ds)->ds_snapnames_zapobj != 0) {
 		err = zap_count(dmu_objset_pool(ds->ds_objset)->dp_meta_objset,
 		    dsl_dataset_phys(ds)->ds_snapnames_zapobj, &snap_count);
 		if (err != 0) {
 			zfs_exit(zfsvfs, FTAG);
 			return (err);
 		}
 		vap->va_nlink += snap_count;
 	}
 	vap->va_size = vap->va_nlink;
 
 	zfs_exit(zfsvfs, FTAG);
 	return (0);
 }
 
 static struct vop_vector zfsctl_ops_snapdir = {
 	.vop_default =	&default_vnodeops,
 	.vop_fplookup_vexec = VOP_EAGAIN,
 	.vop_fplookup_symlink = VOP_EAGAIN,
 	.vop_open =	zfsctl_common_open,
 	.vop_close =	zfsctl_common_close,
 	.vop_getattr =	zfsctl_snapdir_getattr,
 	.vop_access =	zfsctl_common_access,
 	.vop_readdir =	zfsctl_snapdir_readdir,
 	.vop_lookup =	zfsctl_snapdir_lookup,
 	.vop_reclaim =	zfsctl_common_reclaim,
 	.vop_fid =	zfsctl_common_fid,
 	.vop_print =	zfsctl_common_print,
 	.vop_pathconf =	zfsctl_common_pathconf,
 	.vop_getacl =	zfsctl_common_getacl,
 #if __FreeBSD_version >= 1400043
 	.vop_add_writecount =	vop_stdadd_writecount_nomsync,
 #endif
 };
 VFS_VOP_VECTOR_REGISTER(zfsctl_ops_snapdir);
 
 
 static int
 zfsctl_snapshot_inactive(struct vop_inactive_args *ap)
 {
 	vnode_t *vp = ap->a_vp;
 
 	vrecycle(vp);
 	return (0);
 }
 
 static int
 zfsctl_snapshot_reclaim(struct vop_reclaim_args *ap)
 {
 	vnode_t *vp = ap->a_vp;
 	void *data = vp->v_data;
 
 	sfs_reclaim_vnode(vp);
 	sfs_destroy_node(data);
 	return (0);
 }
 
 static int
 zfsctl_snapshot_vptocnp(struct vop_vptocnp_args *ap)
 {
 	struct mount *mp;
 	vnode_t *dvp;
 	vnode_t *vp;
 	sfs_node_t *node;
 	size_t len;
 	int locked;
 	int error;
 
 	vp = ap->a_vp;
 	node = vp->v_data;
 	len = strlen(node->sn_name);
 	if (*ap->a_buflen < len)
 		return (SET_ERROR(ENOMEM));
 
 	/*
 	 * Prevent unmounting of the snapshot while the vnode lock
 	 * is not held.  That is not strictly required, but allows
 	 * us to assert that an uncovered snapshot vnode is never
 	 * "leaked".
 	 */
 	mp = vp->v_mountedhere;
 	if (mp == NULL)
 		return (SET_ERROR(ENOENT));
 	error = vfs_busy(mp, 0);
 	KASSERT(error == 0, ("vfs_busy(mp, 0) failed with %d", error));
 
 	/*
 	 * We can vput the vnode as we can now depend on the reference owned
 	 * by the busied mp.  But we also need to hold the vnode, because
 	 * the reference may go after vfs_unbusy() which has to be called
 	 * before we can lock the vnode again.
 	 */
 	locked = VOP_ISLOCKED(vp);
 	enum vgetstate vs = vget_prep(vp);
 	vput(vp);
 
 	/* Look up .zfs/snapshot, our parent. */
 	error = zfsctl_snapdir_vnode(vp->v_mount, NULL, LK_SHARED, &dvp);
 	if (error == 0) {
 		VOP_UNLOCK(dvp);
 		*ap->a_vpp = dvp;
 		*ap->a_buflen -= len;
 		memcpy(ap->a_buf + *ap->a_buflen, node->sn_name, len);
 	}
 	vfs_unbusy(mp);
 	vget_finish(vp, locked | LK_RETRY, vs);
 	return (error);
 }
 
 /*
  * These VP's should never see the light of day.  They should always
  * be covered.
  */
 static struct vop_vector zfsctl_ops_snapshot = {
 	.vop_default =		NULL, /* ensure very restricted access */
 	.vop_fplookup_vexec =	VOP_EAGAIN,
 	.vop_fplookup_symlink = VOP_EAGAIN,
 	.vop_open =		zfsctl_common_open,
 	.vop_close =		zfsctl_common_close,
 	.vop_inactive =		zfsctl_snapshot_inactive,
 	.vop_need_inactive =	vop_stdneed_inactive,
 	.vop_reclaim =		zfsctl_snapshot_reclaim,
 	.vop_vptocnp =		zfsctl_snapshot_vptocnp,
 	.vop_lock1 =		vop_stdlock,
 	.vop_unlock =		vop_stdunlock,
 	.vop_islocked =		vop_stdislocked,
 	.vop_advlockpurge =	vop_stdadvlockpurge, /* called by vgone */
 	.vop_print =		zfsctl_common_print,
 #if __FreeBSD_version >= 1400043
 	.vop_add_writecount =	vop_stdadd_writecount_nomsync,
 #endif
 };
 VFS_VOP_VECTOR_REGISTER(zfsctl_ops_snapshot);
 
 int
 zfsctl_lookup_objset(vfs_t *vfsp, uint64_t objsetid, zfsvfs_t **zfsvfsp)
 {
 	zfsvfs_t *zfsvfs __unused = vfsp->vfs_data;
 	vnode_t *vp;
 	int error;
 
 	ASSERT3P(zfsvfs->z_ctldir, !=, NULL);
 	*zfsvfsp = NULL;
 	error = sfs_vnode_get(vfsp, LK_EXCLUSIVE,
 	    ZFSCTL_INO_SNAPDIR, objsetid, &vp);
 	if (error == 0 && vp != NULL) {
 		/*
 		 * XXX Probably need to at least reference, if not busy, the mp.
 		 */
 		if (vp->v_mountedhere != NULL)
 			*zfsvfsp = vp->v_mountedhere->mnt_data;
 		vput(vp);
 	}
 	if (*zfsvfsp == NULL)
 		return (SET_ERROR(EINVAL));
 	return (0);
 }
 
 /*
  * Unmount any snapshots for the given filesystem.  This is called from
  * zfs_umount() - if we have a ctldir, then go through and unmount all the
  * snapshots.
  */
 int
 zfsctl_umount_snapshots(vfs_t *vfsp, int fflags, cred_t *cr)
 {
 	char snapname[ZFS_MAX_DATASET_NAME_LEN];
 	zfsvfs_t *zfsvfs = vfsp->vfs_data;
 	struct mount *mp;
 	vnode_t *vp;
 	uint64_t cookie;
 	int error;
 
 	ASSERT3P(zfsvfs->z_ctldir, !=, NULL);
 
 	cookie = 0;
 	for (;;) {
 		uint64_t id;
 
 		dsl_pool_config_enter(dmu_objset_pool(zfsvfs->z_os), FTAG);
 		error = dmu_snapshot_list_next(zfsvfs->z_os, sizeof (snapname),
 		    snapname, &id, &cookie, NULL);
 		dsl_pool_config_exit(dmu_objset_pool(zfsvfs->z_os), FTAG);
 		if (error != 0) {
 			if (error == ENOENT)
 				error = 0;
 			break;
 		}
 
 		for (;;) {
 			error = sfs_vnode_get(vfsp, LK_EXCLUSIVE,
 			    ZFSCTL_INO_SNAPDIR, id, &vp);
 			if (error != 0 || vp == NULL)
 				break;
 
 			mp = vp->v_mountedhere;
 
 			/*
 			 * v_mountedhere being NULL means that the
 			 * (uncovered) vnode is in a transient state
 			 * (mounting or unmounting), so loop until it
 			 * settles down.
 			 */
 			if (mp != NULL)
 				break;
 			vput(vp);
 		}
 		if (error != 0)
 			break;
 		if (vp == NULL)
 			continue;	/* no mountpoint, nothing to do */
 
 		/*
 		 * The mount-point vnode is kept locked to avoid spurious EBUSY
 		 * from a concurrent umount.
 		 * The vnode lock must have recursive locking enabled.
 		 */
 		vfs_ref(mp);
 		error = dounmount(mp, fflags, curthread);
 		KASSERT_IMPLY(error == 0, vrefcnt(vp) == 1,
 		    ("extra references after unmount"));
 		vput(vp);
 		if (error != 0)
 			break;
 	}
 	KASSERT_IMPLY((fflags & MS_FORCE) != 0, error == 0,
 	    ("force unmounting failed"));
 	return (error);
 }
 
 int
 zfsctl_snapshot_unmount(const char *snapname, int flags __unused)
 {
 	vfs_t *vfsp = NULL;
 	zfsvfs_t *zfsvfs = NULL;
 
 	if (strchr(snapname, '@') == NULL)
 		return (0);
 
 	int err = getzfsvfs(snapname, &zfsvfs);
 	if (err != 0) {
 		ASSERT3P(zfsvfs, ==, NULL);
 		return (0);
 	}
 	vfsp = zfsvfs->z_vfs;
 
 	ASSERT(!dsl_pool_config_held(dmu_objset_pool(zfsvfs->z_os)));
 
 	vfs_ref(vfsp);
 	vfs_unbusy(vfsp);
 	return (dounmount(vfsp, MS_FORCE, curthread));
 }