Index: projects/fuse2/sys/fs/fuse/fuse_vnops.c
===================================================================
--- projects/fuse2/sys/fs/fuse/fuse_vnops.c	(revision 347216)
+++ projects/fuse2/sys/fs/fuse/fuse_vnops.c	(revision 347217)
@@ -1,2395 +1,2420 @@
 /*-
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * Copyright (c) 2007-2009 Google Inc. and Amit Singh
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  * * Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  * * 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.
  * * Neither the name of Google Inc. nor the names of its
  *   contributors may be used to endorse or promote products derived from
  *   this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
  * OWNER 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.
  *
  * Copyright (C) 2005 Csaba Henk.
  * 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 AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/module.h>
 #include <sys/systm.h>
 #include <sys/errno.h>
 #include <sys/kernel.h>
 #include <sys/conf.h>
 #include <sys/uio.h>
 #include <sys/malloc.h>
 #include <sys/queue.h>
 #include <sys/lock.h>
 #include <sys/rwlock.h>
 #include <sys/sx.h>
 #include <sys/proc.h>
 #include <sys/mount.h>
 #include <sys/vnode.h>
 #include <sys/namei.h>
 #include <sys/extattr.h>
 #include <sys/stat.h>
 #include <sys/unistd.h>
 #include <sys/filedesc.h>
 #include <sys/file.h>
 #include <sys/fcntl.h>
 #include <sys/dirent.h>
 #include <sys/bio.h>
 #include <sys/buf.h>
 #include <sys/sysctl.h>
 #include <sys/vmmeter.h>
 
 #include <vm/vm.h>
 #include <vm/vm_extern.h>
 #include <vm/pmap.h>
 #include <vm/vm_map.h>
 #include <vm/vm_page.h>
 #include <vm/vm_param.h>
 #include <vm/vm_object.h>
 #include <vm/vm_pager.h>
 #include <vm/vnode_pager.h>
 #include <vm/vm_object.h>
 
 #include "fuse.h"
 #include "fuse_file.h"
 #include "fuse_internal.h"
 #include "fuse_ipc.h"
 #include "fuse_node.h"
 #include "fuse_io.h"
 
 #include <sys/priv.h>
 
 /* Maximum number of hardlinks to a single FUSE file */
 #define FUSE_LINK_MAX                      UINT32_MAX
 
 SDT_PROVIDER_DECLARE(fusefs);
 /* 
  * Fuse trace probe:
  * arg0: verbosity.  Higher numbers give more verbose messages
  * arg1: Textual message
  */
 SDT_PROBE_DEFINE2(fusefs, , vnops, trace, "int", "char*");
 
 /* vnode ops */
 static vop_access_t fuse_vnop_access;
 static vop_advlock_t fuse_vnop_advlock;
 static vop_close_t fuse_fifo_close;
 static vop_close_t fuse_vnop_close;
 static vop_create_t fuse_vnop_create;
 static vop_deleteextattr_t fuse_vnop_deleteextattr;
 static vop_fdatasync_t fuse_vnop_fdatasync;
 static vop_fsync_t fuse_vnop_fsync;
 static vop_getattr_t fuse_vnop_getattr;
 static vop_getextattr_t fuse_vnop_getextattr;
 static vop_inactive_t fuse_vnop_inactive;
 static vop_link_t fuse_vnop_link;
 static vop_listextattr_t fuse_vnop_listextattr;
 static vop_lookup_t fuse_vnop_lookup;
 static vop_mkdir_t fuse_vnop_mkdir;
 static vop_mknod_t fuse_vnop_mknod;
 static vop_open_t fuse_vnop_open;
 static vop_pathconf_t fuse_vnop_pathconf;
 static vop_read_t fuse_vnop_read;
 static vop_readdir_t fuse_vnop_readdir;
 static vop_readlink_t fuse_vnop_readlink;
 static vop_reclaim_t fuse_vnop_reclaim;
 static vop_remove_t fuse_vnop_remove;
 static vop_rename_t fuse_vnop_rename;
 static vop_rmdir_t fuse_vnop_rmdir;
 static vop_setattr_t fuse_vnop_setattr;
 static vop_setextattr_t fuse_vnop_setextattr;
 static vop_strategy_t fuse_vnop_strategy;
 static vop_symlink_t fuse_vnop_symlink;
 static vop_write_t fuse_vnop_write;
 static vop_getpages_t fuse_vnop_getpages;
 static vop_putpages_t fuse_vnop_putpages;
 static vop_print_t fuse_vnop_print;
 
 struct vop_vector fuse_fifoops = {
 	.vop_default =		&fifo_specops,
 	.vop_access =		fuse_vnop_access,
 	.vop_close =		fuse_fifo_close,
 	.vop_fsync =		fuse_vnop_fsync,
 	.vop_getattr =		fuse_vnop_getattr,
 	.vop_inactive =		fuse_vnop_inactive,
 	.vop_pathconf =		fuse_vnop_pathconf,
 	.vop_print =		fuse_vnop_print,
 	.vop_read =		VOP_PANIC,
 	.vop_reclaim =		fuse_vnop_reclaim,
 	.vop_setattr =		fuse_vnop_setattr,
 	.vop_write =		VOP_PANIC,
 };
 
 struct vop_vector fuse_vnops = {
 	.vop_allocate =	VOP_EINVAL,
 	.vop_default = &default_vnodeops,
 	.vop_access = fuse_vnop_access,
 	.vop_advlock = fuse_vnop_advlock,
 	.vop_close = fuse_vnop_close,
 	.vop_create = fuse_vnop_create,
 	.vop_deleteextattr = fuse_vnop_deleteextattr,
 	.vop_fsync = fuse_vnop_fsync,
 	.vop_fdatasync = fuse_vnop_fdatasync,
 	.vop_getattr = fuse_vnop_getattr,
 	.vop_getextattr = fuse_vnop_getextattr,
 	.vop_inactive = fuse_vnop_inactive,
 	.vop_link = fuse_vnop_link,
 	.vop_listextattr = fuse_vnop_listextattr,
 	.vop_lookup = fuse_vnop_lookup,
 	.vop_mkdir = fuse_vnop_mkdir,
 	.vop_mknod = fuse_vnop_mknod,
 	.vop_open = fuse_vnop_open,
 	.vop_pathconf = fuse_vnop_pathconf,
 	.vop_read = fuse_vnop_read,
 	.vop_readdir = fuse_vnop_readdir,
 	.vop_readlink = fuse_vnop_readlink,
 	.vop_reclaim = fuse_vnop_reclaim,
 	.vop_remove = fuse_vnop_remove,
 	.vop_rename = fuse_vnop_rename,
 	.vop_rmdir = fuse_vnop_rmdir,
 	.vop_setattr = fuse_vnop_setattr,
 	.vop_setextattr = fuse_vnop_setextattr,
 	.vop_strategy = fuse_vnop_strategy,
 	.vop_symlink = fuse_vnop_symlink,
 	.vop_write = fuse_vnop_write,
 	.vop_getpages = fuse_vnop_getpages,
 	.vop_putpages = fuse_vnop_putpages,
 	.vop_print = fuse_vnop_print,
 };
 
 static u_long fuse_lookup_cache_hits = 0;
 
 SYSCTL_ULONG(_vfs_fusefs, OID_AUTO, lookup_cache_hits, CTLFLAG_RD,
     &fuse_lookup_cache_hits, 0, "number of positive cache hits in lookup");
 
 static u_long fuse_lookup_cache_misses = 0;
 
 SYSCTL_ULONG(_vfs_fusefs, OID_AUTO, lookup_cache_misses, CTLFLAG_RD,
     &fuse_lookup_cache_misses, 0, "number of cache misses in lookup");
 
 /*
  * XXX: This feature is highly experimental and can bring to instabilities,
  * needs revisiting before to be enabled by default.
  */
 static int fuse_reclaim_revoked = 0;
 
 SYSCTL_INT(_vfs_fusefs, OID_AUTO, reclaim_revoked, CTLFLAG_RW,
     &fuse_reclaim_revoked, 0, "");
 
 uma_zone_t fuse_pbuf_zone;
 
 #define fuse_vm_page_lock(m)		vm_page_lock((m));
 #define fuse_vm_page_unlock(m)		vm_page_unlock((m));
 #define fuse_vm_page_lock_queues()	((void)0)
 #define fuse_vm_page_unlock_queues()	((void)0)
 
 /* Check permission for extattr operations, much like extattr_check_cred */
 static int
 fuse_extattr_check_cred(struct vnode *vp, int ns, struct ucred *cred,
 	struct thread *td, accmode_t accmode)
 {
 	struct mount *mp = vnode_mount(vp);
 	struct fuse_data *data = fuse_get_mpdata(mp);
 
 	/*
 	 * Kernel-invoked always succeeds.
 	 */
 	if (cred == NOCRED)
 		return (0);
 
 	/*
 	 * Do not allow privileged processes in jail to directly manipulate
 	 * system attributes.
 	 */
 	switch (ns) {
 	case EXTATTR_NAMESPACE_SYSTEM:
 		if (data->dataflags & FSESS_DEFAULT_PERMISSIONS) {
 			return (priv_check_cred(cred, PRIV_VFS_EXTATTR_SYSTEM));
 		}
 		/* FALLTHROUGH */
 	case EXTATTR_NAMESPACE_USER:
 		return (fuse_internal_access(vp, accmode, td, cred));
 	default:
 		return (EPERM);
 	}
 }
 
 /* Get a filehandle for a directory */
 static int
 fuse_filehandle_get_dir(struct vnode *vp, struct fuse_filehandle **fufhp,
 	struct ucred *cred, pid_t pid)
 {
 	if (fuse_filehandle_get(vp, FREAD, fufhp, cred, pid) == 0)
 		return 0;
 	return fuse_filehandle_get(vp, FEXEC, fufhp, cred, pid);
 }
 
 /* Send FUSE_FLUSH for this vnode */
 static int
 fuse_flush(struct vnode *vp, struct ucred *cred, pid_t pid, int fflag)
 {
 	struct fuse_flush_in *ffi;
 	struct fuse_filehandle *fufh;
 	struct fuse_dispatcher fdi;
 	struct thread *td = curthread;
 	struct mount *mp = vnode_mount(vp);
 	int err;
 
 	if (!fsess_isimpl(vnode_mount(vp), FUSE_FLUSH))
 		return 0;
 
 	err = fuse_filehandle_getrw(vp, fflag, &fufh, cred, pid);
 	if (err)
 		return err;
 
 	fdisp_init(&fdi, sizeof(*ffi));
 	fdisp_make_vp(&fdi, FUSE_FLUSH, vp, td, cred);
 	ffi = fdi.indata;
 	ffi->fh = fufh->fh_id;
 	/* 
 	 * If the file has a POSIX lock then we're supposed to set lock_owner.
 	 * If not, then lock_owner is undefined.  So we may as well always set
 	 * it.
 	 */
 	ffi->lock_owner = td->td_proc->p_pid;
 
 	err = fdisp_wait_answ(&fdi);
 	if (err == ENOSYS) {
 		fsess_set_notimpl(mp, FUSE_FLUSH);
 		err = 0;
 	}
 	fdisp_destroy(&fdi);
 	return err;
 }
 
 /* Close wrapper for fifos.  */
 static int
 fuse_fifo_close(struct vop_close_args *ap)
 {
 	return (fifo_specops.vop_close(ap));
 }
 
 /*
     struct vnop_access_args {
 	struct vnode *a_vp;
 #if VOP_ACCESS_TAKES_ACCMODE_T
 	accmode_t a_accmode;
 #else
 	int a_mode;
 #endif
 	struct ucred *a_cred;
 	struct thread *a_td;
     };
 */
 static int
 fuse_vnop_access(struct vop_access_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	int accmode = ap->a_accmode;
 	struct ucred *cred = ap->a_cred;
 
 	struct fuse_data *data = fuse_get_mpdata(vnode_mount(vp));
 
 	int err;
 
 	if (fuse_isdeadfs(vp)) {
 		if (vnode_isvroot(vp)) {
 			return 0;
 		}
 		return ENXIO;
 	}
 	if (!(data->dataflags & FSESS_INITED)) {
 		if (vnode_isvroot(vp)) {
 			if (priv_check_cred(cred, PRIV_VFS_ADMIN) ||
 			    (fuse_match_cred(data->daemoncred, cred) == 0)) {
 				return 0;
 			}
 		}
 		return EBADF;
 	}
 	if (vnode_islnk(vp)) {
 		return 0;
 	}
 
 	err = fuse_internal_access(vp, accmode, ap->a_td, ap->a_cred);
 	return err;
 }
 
 /*
  * struct vop_advlock_args {
  *	struct vop_generic_args a_gen;
  *	struct vnode *a_vp;
  *	void *a_id;
  *	int a_op;
  *	struct flock *a_fl;
  *	int a_flags;
  * }
  */
 static int
 fuse_vnop_advlock(struct vop_advlock_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct flock *fl = ap->a_fl;
 	struct thread *td = curthread;
 	struct ucred *cred = td->td_ucred;
 	pid_t pid = td->td_proc->p_pid;
 	struct fuse_filehandle *fufh;
 	struct fuse_dispatcher fdi;
 	struct fuse_lk_in *fli;
 	struct fuse_lk_out *flo;
 	enum fuse_opcode op;
 	int dataflags, err;
 
 	dataflags = fuse_get_mpdata(vnode_mount(vp))->dataflags;
 
 	if (fuse_isdeadfs(vp)) {
 		return ENXIO;
 	}
 
 	if (!(dataflags & FSESS_POSIX_LOCKS))
 		return vop_stdadvlock(ap);
 
 	err = fuse_filehandle_get_anyflags(vp, &fufh, cred, pid);
 	if (err)
 		return err;
 
 	fdisp_init(&fdi, sizeof(*fli));
 
 	switch(ap->a_op) {
 	case F_GETLK:
 		op = FUSE_GETLK;
 		break;
 	case F_SETLK:
 		op = FUSE_SETLK;
 		break;
 	case F_SETLKW:
 		op = FUSE_SETLKW;
 		break;
 	default:
 		return EINVAL;
 	}
 
 	fdisp_make_vp(&fdi, op, vp, td, cred);
 	fli = fdi.indata;
 	fli->fh = fufh->fh_id;
 	fli->owner = fl->l_pid;
 	fli->lk.start = fl->l_start;
 	if (fl->l_len != 0)
 		fli->lk.end = fl->l_start + fl->l_len - 1;
 	else
 		fli->lk.end = INT64_MAX;
 	fli->lk.type = fl->l_type;
 	fli->lk.pid = fl->l_pid;
 
 	err = fdisp_wait_answ(&fdi);
 	fdisp_destroy(&fdi);
 
 	if (err == 0 && op == FUSE_GETLK) {
 		flo = fdi.answ;
 		fl->l_type = flo->lk.type;
 		fl->l_pid = flo->lk.pid;
 		if (flo->lk.type != F_UNLCK) {
 			fl->l_start = flo->lk.start;
 			if (flo->lk.end == INT64_MAX)
 				fl->l_len = 0;
 			else
 				fl->l_len = flo->lk.end - flo->lk.start + 1;
 			fl->l_start = flo->lk.start;
 		}
 	}
 
 	return err;
 }
 
 /*
     struct vop_close_args {
 	struct vnode *a_vp;
 	int  a_fflag;
 	struct ucred *a_cred;
 	struct thread *a_td;
     };
 */
 static int
 fuse_vnop_close(struct vop_close_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct ucred *cred = ap->a_cred;
 	int fflag = ap->a_fflag;
 	struct thread *td = ap->a_td;
 	pid_t pid = td->td_proc->p_pid;
 	int err = 0;
 
 	if (fuse_isdeadfs(vp))
 		return 0;
 	if (vnode_isdir(vp))
 		return 0;
 	if (fflag & IO_NDELAY)
 		return 0;
 
 	err = fuse_flush(vp, cred, pid, fflag);
 	/* TODO: close the file handle, if we're sure it's no longer used */
 	if ((VTOFUD(vp)->flag & FN_SIZECHANGE) != 0) {
 		fuse_vnode_savesize(vp, cred, td->td_proc->p_pid);
 	}
 	return err;
 }
 
 static void
 fdisp_make_mknod_for_fallback(
 	struct fuse_dispatcher *fdip,
 	struct componentname *cnp,
 	struct vnode *dvp,
 	uint64_t parentnid,
 	struct thread *td,
 	struct ucred *cred,
 	mode_t mode,
 	enum fuse_opcode *op)
 {
 	struct fuse_mknod_in *fmni;
 
 	fdisp_init(fdip, sizeof(*fmni) + cnp->cn_namelen + 1);
 	*op = FUSE_MKNOD;
 	fdisp_make(fdip, *op, vnode_mount(dvp), parentnid, td, cred);
 	fmni = fdip->indata;
 	fmni->mode = mode;
 	fmni->rdev = 0;
 	memcpy((char *)fdip->indata + sizeof(*fmni), cnp->cn_nameptr,
 	    cnp->cn_namelen);
 	((char *)fdip->indata)[sizeof(*fmni) + cnp->cn_namelen] = '\0';
 }
 /*
     struct vnop_create_args {
 	struct vnode *a_dvp;
 	struct vnode **a_vpp;
 	struct componentname *a_cnp;
 	struct vattr *a_vap;
     };
 */
 static int
 fuse_vnop_create(struct vop_create_args *ap)
 {
 	struct vnode *dvp = ap->a_dvp;
 	struct vnode **vpp = ap->a_vpp;
 	struct componentname *cnp = ap->a_cnp;
 	struct vattr *vap = ap->a_vap;
 	struct thread *td = cnp->cn_thread;
 	struct ucred *cred = cnp->cn_cred;
 
 	struct fuse_open_in *foi;
 	struct fuse_entry_out *feo;
 	struct fuse_open_out *foo;
 	struct fuse_dispatcher fdi, fdi2;
 	struct fuse_dispatcher *fdip = &fdi;
 	struct fuse_dispatcher *fdip2 = NULL;
 
 	int err;
 
 	struct mount *mp = vnode_mount(dvp);
 	uint64_t parentnid = VTOFUD(dvp)->nid;
 	mode_t mode = MAKEIMODE(vap->va_type, vap->va_mode);
 	enum fuse_opcode op;
 	int flags;
 
 	/* 
 	 * VOP_CREATE doesn't tell us the open(2) flags, so we guess.  Only a
 	 * writable mode makes sense, and we might as well include readability
 	 * too.
 	 */
 	flags = O_RDWR;
 
 	if (fuse_isdeadfs(dvp)) {
 		return ENXIO;
 	}
 	bzero(&fdi, sizeof(fdi));
 
 	if ((vap->va_type != VREG && vap->va_type != VSOCK))
 		return (EINVAL);
 
 	if (!fsess_isimpl(mp, FUSE_CREATE)) {
 		/* Fallback to FUSE_MKNOD/FUSE_OPEN */
 		fdisp_make_mknod_for_fallback(fdip, cnp, dvp, parentnid, td,
 			cred, mode, &op);
 	} else {
 		/* Use FUSE_CREATE */
 		op = FUSE_CREATE;
 		fdisp_init(fdip, sizeof(*foi) + cnp->cn_namelen + 1);
 		fdisp_make(fdip, op, vnode_mount(dvp), parentnid, td, cred);
 		foi = fdip->indata;
 		foi->mode = mode;
 		foi->flags = O_CREAT | flags;
 		memcpy((char *)fdip->indata + sizeof(*foi), cnp->cn_nameptr,
 		    cnp->cn_namelen);
 		((char *)fdip->indata)[sizeof(*foi) + cnp->cn_namelen] = '\0';
 	}
 
 	err = fdisp_wait_answ(fdip);
 
 	if (err) {
 		if (err == ENOSYS && op == FUSE_CREATE) {
 			fsess_set_notimpl(mp, FUSE_CREATE);
 			fdisp_make_mknod_for_fallback(fdip, cnp, dvp,
 				parentnid, td, cred, mode, &op);
 			err = fdisp_wait_answ(fdip);
 		}
 		if (err)
 			goto out;
 	}
 
 	feo = fdip->answ;
 
 	if ((err = fuse_internal_checkentry(feo, vap->va_type))) {
 		goto out;
 	}
 
 	if (op == FUSE_CREATE) {
 		foo = (struct fuse_open_out*)(feo + 1);
 	} else {
 		/* Issue a separate FUSE_OPEN */
 		fdip2 = &fdi2;
 		fdisp_init(fdip2, sizeof(*foi));
 		fdisp_make(fdip2, FUSE_OPEN, vnode_mount(dvp), feo->nodeid, td,
 			cred);
 		foi = fdip2->indata;
 		foi->mode = mode;
 		foi->flags = flags;
 		err = fdisp_wait_answ(fdip2);
 		if (err)
 			goto out;
 		foo = fdip2->answ;
 	}
 	err = fuse_vnode_get(mp, feo, feo->nodeid, dvp, vpp, cnp, vap->va_type);
 	if (err) {
 		struct fuse_release_in *fri;
 		uint64_t nodeid = feo->nodeid;
 		uint64_t fh_id = foo->fh;
 
 		fdisp_init(fdip, sizeof(*fri));
 		fdisp_make(fdip, FUSE_RELEASE, mp, nodeid, td, cred);
 		fri = fdip->indata;
 		fri->fh = fh_id;
 		fri->flags = flags;
 		fuse_insert_callback(fdip->tick, fuse_internal_forget_callback);
 		fuse_insert_message(fdip->tick, false);
 		goto out;
 	}
 	ASSERT_VOP_ELOCKED(*vpp, "fuse_vnop_create");
 	fuse_internal_cache_attrs(*vpp, &feo->attr, feo->attr_valid,
 		feo->attr_valid_nsec, NULL);
 
 	fuse_filehandle_init(*vpp, FUFH_RDWR, NULL, td, cred, foo);
 	fuse_vnode_open(*vpp, foo->open_flags, td);
 	cache_purge_negative(dvp);
 
 out:
 	if (fdip2)
 		fdisp_destroy(fdip2);
 	fdisp_destroy(fdip);
 	return err;
 }
 
 /*
     struct vnop_fdatasync_args {
 	struct vop_generic_args a_gen;
 	struct vnode * a_vp;
 	struct thread * a_td;
     };
 */
 static int
 fuse_vnop_fdatasync(struct vop_fdatasync_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct thread *td = ap->a_td;
 	int waitfor = MNT_WAIT;
 
 	int err = 0;
 
 	if (fuse_isdeadfs(vp)) {
 		return 0;
 	}
 	if ((err = vop_stdfdatasync_buf(ap)))
 		return err;
 
 	return fuse_internal_fsync(vp, td, waitfor, true);
 }
 
 /*
     struct vnop_fsync_args {
 	struct vop_generic_args a_gen;
 	struct vnode * a_vp;
 	int  a_waitfor;
 	struct thread * a_td;
     };
 */
 static int
 fuse_vnop_fsync(struct vop_fsync_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct thread *td = ap->a_td;
 	int waitfor = ap->a_waitfor;
 	int err = 0;
 
 	if (fuse_isdeadfs(vp)) {
 		return 0;
 	}
 	if ((err = vop_stdfsync(ap)))
 		return err;
 
 	return fuse_internal_fsync(vp, td, waitfor, false);
 }
 
 /*
     struct vnop_getattr_args {
 	struct vnode *a_vp;
 	struct vattr *a_vap;
 	struct ucred *a_cred;
 	struct thread *a_td;
     };
 */
 static int
 fuse_vnop_getattr(struct vop_getattr_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct vattr *vap = ap->a_vap;
 	struct ucred *cred = ap->a_cred;
 	struct thread *td = curthread;
 
 	int err = 0;
 	int dataflags;
 
 	dataflags = fuse_get_mpdata(vnode_mount(vp))->dataflags;
 
 	/* Note that we are not bailing out on a dead file system just yet. */
 
 	if (!(dataflags & FSESS_INITED)) {
 		if (!vnode_isvroot(vp)) {
 			fdata_set_dead(fuse_get_mpdata(vnode_mount(vp)));
 			err = ENOTCONN;
 			return err;
 		} else {
 			goto fake;
 		}
 	}
 	err = fuse_internal_getattr(vp, vap, cred, td);
 	if (err == ENOTCONN && vnode_isvroot(vp)) {
 		/* see comment in fuse_vfsop_statfs() */
 		goto fake;
 	} else {
 		return err;
 	}
 
 fake:
 	bzero(vap, sizeof(*vap));
 	vap->va_type = vnode_vtype(vp);
 
 	return 0;
 }
 
 /*
     struct vnop_inactive_args {
 	struct vnode *a_vp;
 	struct thread *a_td;
     };
 */
 static int
 fuse_vnop_inactive(struct vop_inactive_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct thread *td = ap->a_td;
 
 	struct fuse_vnode_data *fvdat = VTOFUD(vp);
 	struct fuse_filehandle *fufh, *fufh_tmp;
 
 	int need_flush = 1;
 
 	LIST_FOREACH_SAFE(fufh, &fvdat->handles, next, fufh_tmp) {
 		if (need_flush && vp->v_type == VREG) {
 			if ((VTOFUD(vp)->flag & FN_SIZECHANGE) != 0) {
 				fuse_vnode_savesize(vp, NULL, 0);
 			}
 			if (fuse_data_cache_invalidate ||
 			    (fvdat->flag & FN_REVOKED) != 0)
 				fuse_io_invalbuf(vp, td);
 			else
 				fuse_io_flushbuf(vp, MNT_WAIT, td);
 			need_flush = 0;
 		}
 		fuse_filehandle_close(vp, fufh, td, NULL);
 	}
 
 	if ((fvdat->flag & FN_REVOKED) != 0 && fuse_reclaim_revoked) {
 		vrecycle(vp);
 	}
 	return 0;
 }
 
 /*
     struct vnop_link_args {
 	struct vnode *a_tdvp;
 	struct vnode *a_vp;
 	struct componentname *a_cnp;
     };
 */
 static int
 fuse_vnop_link(struct vop_link_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct vnode *tdvp = ap->a_tdvp;
 	struct componentname *cnp = ap->a_cnp;
 
 	struct vattr *vap = VTOVA(vp);
 
 	struct fuse_dispatcher fdi;
 	struct fuse_entry_out *feo;
 	struct fuse_link_in fli;
 
 	int err;
 
 	if (fuse_isdeadfs(vp)) {
 		return ENXIO;
 	}
 	if (vnode_mount(tdvp) != vnode_mount(vp)) {
 		return EXDEV;
 	}
 
 	/*
 	 * This is a seatbelt check to protect naive userspace filesystems from
 	 * themselves and the limitations of the FUSE IPC protocol.  If a
 	 * filesystem does not allow attribute caching, assume it is capable of
 	 * validating that nlink does not overflow.
 	 */
 	if (vap != NULL && vap->va_nlink >= FUSE_LINK_MAX)
 		return EMLINK;
 	fli.oldnodeid = VTOI(vp);
 
 	fdisp_init(&fdi, 0);
 	fuse_internal_newentry_makerequest(vnode_mount(tdvp), VTOI(tdvp), cnp,
 	    FUSE_LINK, &fli, sizeof(fli), &fdi);
 	if ((err = fdisp_wait_answ(&fdi))) {
 		goto out;
 	}
 	feo = fdi.answ;
 
 	err = fuse_internal_checkentry(feo, vnode_vtype(vp));
 out:
 	fdisp_destroy(&fdi);
 	return err;
 }
 
 struct fuse_lookup_alloc_arg {
 	struct fuse_entry_out *feo;
 	struct componentname *cnp;
 	uint64_t nid;
 	enum vtype vtyp;
 };
 
 /* Callback for vn_get_ino */
 static int
 fuse_lookup_alloc(struct mount *mp, void *arg, int lkflags, struct vnode **vpp)
 {
 	struct fuse_lookup_alloc_arg *flaa = arg;
 
 	return fuse_vnode_get(mp, flaa->feo, flaa->nid, NULL, vpp, flaa->cnp,
 		flaa->vtyp);
 }
 
 SDT_PROBE_DEFINE3(fusefs, , vnops, cache_lookup,
 	"int", "struct timespec*", "struct timespec*");
 /*
     struct vnop_lookup_args {
 	struct vnodeop_desc *a_desc;
 	struct vnode *a_dvp;
 	struct vnode **a_vpp;
 	struct componentname *a_cnp;
     };
 */
 int
 fuse_vnop_lookup(struct vop_lookup_args *ap)
 {
 	struct vnode *dvp = ap->a_dvp;
 	struct vnode **vpp = ap->a_vpp;
 	struct componentname *cnp = ap->a_cnp;
 	struct thread *td = cnp->cn_thread;
 	struct ucred *cred = cnp->cn_cred;
 
 	int nameiop = cnp->cn_nameiop;
 	int flags = cnp->cn_flags;
 	int wantparent = flags & (LOCKPARENT | WANTPARENT);
 	int islastcn = flags & ISLASTCN;
 	struct mount *mp = vnode_mount(dvp);
 
 	int err = 0;
 	int lookup_err = 0;
 	struct vnode *vp = NULL;
 
 	struct fuse_dispatcher fdi;
 	bool did_lookup = false;
 	struct fuse_entry_out *feo = NULL;
 	enum vtype vtyp;	/* vnode type of target */
 	off_t filesize;		/* filesize of target */
 
 	uint64_t nid;
 
 	if (fuse_isdeadfs(dvp)) {
 		*vpp = NULL;
 		return ENXIO;
 	}
 	if (!vnode_isdir(dvp))
 		return ENOTDIR;
 
 	if (islastcn && vfs_isrdonly(mp) && (nameiop != LOOKUP))
 		return EROFS;
 
 	if ((err = fuse_internal_access(dvp, VEXEC, td, cred)))
 		return err;
 
 	if (flags & ISDOTDOT) {
 		nid = VTOFUD(dvp)->parent_nid;
 		if (nid == 0)
 			return ENOENT;
 		/* .. is obviously a directory */
 		vtyp = VDIR;
 		filesize = 0;
 	} else if (cnp->cn_namelen == 1 && *(cnp->cn_nameptr) == '.') {
 		nid = VTOI(dvp);
 		/* . is obviously a directory */
 		vtyp = VDIR;
 		filesize = 0;
 	} else {
 		struct timespec now, timeout;
 
 		err = cache_lookup(dvp, vpp, cnp, &timeout, NULL);
 		getnanouptime(&now);
 		SDT_PROBE3(fusefs, , vnops, cache_lookup, err, &timeout, &now);
 		switch (err) {
 		case -1:		/* positive match */
 			if (timespeccmp(&timeout, &now, >)) {
 				atomic_add_acq_long(&fuse_lookup_cache_hits, 1);
 			} else {
 				/* Cache timeout */
 				atomic_add_acq_long(&fuse_lookup_cache_misses,
 					1);
 				cache_purge(*vpp);
 				if (dvp != *vpp)
 					vput(*vpp);
 				else 
 					vrele(*vpp);
 				*vpp = NULL;
 				break;
 			}
 			return 0;
 
 		case 0:		/* no match in cache */
 			atomic_add_acq_long(&fuse_lookup_cache_misses, 1);
 			break;
 
 		case ENOENT:		/* negative match */
 			getnanouptime(&now);
 			if (timespeccmp(&timeout, &now, <=)) {
 				/* Cache timeout */
 				cache_purge_negative(dvp);
 				break;
 			}
 			/* fall through */
 		default:
 			return err;
 		}
 
 		nid = VTOI(dvp);
 		fdisp_init(&fdi, cnp->cn_namelen + 1);
 		fdisp_make(&fdi, FUSE_LOOKUP, mp, nid, td, cred);
 
 		memcpy(fdi.indata, cnp->cn_nameptr, cnp->cn_namelen);
 		((char *)fdi.indata)[cnp->cn_namelen] = '\0';
 		lookup_err = fdisp_wait_answ(&fdi);
 		did_lookup = true;
 
 		if (!lookup_err) {
 			/* lookup call succeeded */
 			nid = ((struct fuse_entry_out *)fdi.answ)->nodeid;
 			feo = (struct fuse_entry_out *)fdi.answ;
 			if (nid == 0) {
 				/* zero nodeid means ENOENT and cache it */
 				struct timespec timeout;
 
 				fdi.answ_stat = ENOENT;
 				lookup_err = ENOENT;
 				if (cnp->cn_flags & MAKEENTRY) {
 					fuse_validity_2_timespec(feo, &timeout);
 					cache_enter_time(dvp, *vpp, cnp,
 						&timeout, NULL);
 				}
 			} else if (nid == FUSE_ROOT_ID) {
 				lookup_err = EINVAL;
 			}
 			vtyp = IFTOVT(feo->attr.mode);
 			filesize = feo->attr.size;
 		}
 		if (lookup_err && (!fdi.answ_stat || lookup_err != ENOENT)) {
 			fdisp_destroy(&fdi);
 			return lookup_err;
 		}
 	}
 	/* lookup_err, if non-zero, must be ENOENT at this point */
 
 	if (lookup_err) {
 		/* Entry not found */
 		if ((nameiop == CREATE || nameiop == RENAME) && islastcn) {
 			err = fuse_internal_access(dvp, VWRITE, td, cred);
 			if (!err) {
 				/*
 				 * Set the SAVENAME flag to hold onto the
 				 * pathname for use later in VOP_CREATE or
 				 * VOP_RENAME.
 				 */
 				cnp->cn_flags |= SAVENAME;
 
 				err = EJUSTRETURN;
 			}
 		} else {
 			err = ENOENT;
 		}
 	} else {
 		/* Entry was found */
 		if (flags & ISDOTDOT) {
 			struct fuse_lookup_alloc_arg flaa;
 
 			flaa.nid = nid;
 			flaa.feo = feo;
 			flaa.cnp = cnp;
 			flaa.vtyp = vtyp;
 			err = vn_vget_ino_gen(dvp, fuse_lookup_alloc, &flaa, 0,
 				&vp);
 			*vpp = vp;
 		} else if (nid == VTOI(dvp)) {
 			vref(dvp);
 			*vpp = dvp;
 		} else {
 			struct fuse_vnode_data *fvdat;
 
 			err = fuse_vnode_get(vnode_mount(dvp), feo, nid, dvp,
 			    &vp, cnp, vtyp);
 			if (err)
 				goto out;
 			*vpp = vp;
 
 			fuse_vnode_setparent(vp, dvp);
 
 			/*
 			 * In the case where we are looking up a FUSE node
 			 * represented by an existing cached vnode, and the
 			 * true size reported by FUSE_LOOKUP doesn't match
 			 * the vnode's cached size, fix the vnode cache to
 			 * match the real object size.
 			 *
 			 * We can get here:
 			 * * following attribute cache expiration, or
 			 * * due a bug in the daemon, or
 			 * * the first time that we looked up the file.
 			 */
 			fvdat = VTOFUD(vp);
 			if (vnode_isreg(vp) &&
 			    filesize != fvdat->filesize) {
 				/*
 				 * The FN_SIZECHANGE flag reflects a dirty
 				 * append.  If userspace lets us know our cache
 				 * is invalid, that write was lost.  (Dirty
 				 * writes that do not cause append are also
 				 * lost, but we don't detect them here.)
 				 *
 				 * XXX: Maybe disable WB caching on this mount.
 				 */
 				if (fvdat->flag & FN_SIZECHANGE)
 					printf("%s: WB cache incoherent on "
 					    "%s!\n", __func__,
 					    vnode_mount(vp)->mnt_stat.f_mntonname);
 
 				(void)fuse_vnode_setsize(vp, cred, filesize);
 				fvdat->flag &= ~FN_SIZECHANGE;
 			}
 
 			MPASS(feo != NULL);
 			fuse_internal_cache_attrs(*vpp, &feo->attr,
 				feo->attr_valid, feo->attr_valid_nsec, NULL);
 
 			if ((nameiop == DELETE || nameiop == RENAME) &&
 				islastcn)
 			{
 				struct vattr dvattr;
 
 				err = fuse_internal_access(dvp, VWRITE, td,
 					cred);
 				if (err != 0)
 					goto out;
 				/* 
 				 * if the parent's sticky bit is set, check
 				 * whether we're allowed to remove the file.
 				 * Need to figure out the vnode locking to make
 				 * this work.
 				 */
 				fuse_internal_getattr(dvp, &dvattr, cred, td);
 				if ((dvattr.va_mode & S_ISTXT) &&
 					fuse_internal_access(dvp, VADMIN, td,
 						cred) &&
 					fuse_internal_access(*vpp, VADMIN, td,
 						cred)) {
 					err = EPERM;
 					goto out;
 				}
 			}
 
 			if (islastcn && (
 				(nameiop == DELETE) ||
 				(nameiop == RENAME && wantparent))) {
 				cnp->cn_flags |= SAVENAME;
 			}
 
 		}
 	}
 out:
 	if (err) {
 		if (vp != NULL && dvp != vp)
 			vput(vp);
 		else if (vp != NULL)
 			vrele(vp);
 		*vpp = NULL;
 	}
 	if (did_lookup)
 		fdisp_destroy(&fdi);
 
 	return err;
 }
 
 /*
     struct vnop_mkdir_args {
 	struct vnode *a_dvp;
 	struct vnode **a_vpp;
 	struct componentname *a_cnp;
 	struct vattr *a_vap;
     };
 */
 static int
 fuse_vnop_mkdir(struct vop_mkdir_args *ap)
 {
 	struct vnode *dvp = ap->a_dvp;
 	struct vnode **vpp = ap->a_vpp;
 	struct componentname *cnp = ap->a_cnp;
 	struct vattr *vap = ap->a_vap;
 
 	struct fuse_mkdir_in fmdi;
 
 	if (fuse_isdeadfs(dvp)) {
 		return ENXIO;
 	}
 	fmdi.mode = MAKEIMODE(vap->va_type, vap->va_mode);
 
 	return (fuse_internal_newentry(dvp, vpp, cnp, FUSE_MKDIR, &fmdi,
 	    sizeof(fmdi), VDIR));
 }
 
 /*
     struct vnop_mknod_args {
 	struct vnode *a_dvp;
 	struct vnode **a_vpp;
 	struct componentname *a_cnp;
 	struct vattr *a_vap;
     };
 */
 static int
 fuse_vnop_mknod(struct vop_mknod_args *ap)
 {
 
 	struct vnode *dvp = ap->a_dvp;
 	struct vnode **vpp = ap->a_vpp;
 	struct componentname *cnp = ap->a_cnp;
 	struct vattr *vap = ap->a_vap;
 	struct fuse_mknod_in fmni;
 
 	if (fuse_isdeadfs(dvp))
 		return ENXIO;
 
 	fmni.mode = MAKEIMODE(vap->va_type, vap->va_mode);
 	fmni.rdev = vap->va_rdev;
 	return (fuse_internal_newentry(dvp, vpp, cnp, FUSE_MKNOD, &fmni,
 	    sizeof(fmni), vap->va_type));
 }
 
 /*
     struct vnop_open_args {
 	struct vnode *a_vp;
 	int  a_mode;
 	struct ucred *a_cred;
 	struct thread *a_td;
 	int a_fdidx; / struct file *a_fp;
     };
 */
 static int
 fuse_vnop_open(struct vop_open_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	int a_mode = ap->a_mode;
 	struct thread *td = ap->a_td;
 	struct ucred *cred = ap->a_cred;
 	pid_t pid = td->td_proc->p_pid;
 	struct fuse_vnode_data *fvdat;
 
 	if (fuse_isdeadfs(vp))
 		return ENXIO;
 	if (vp->v_type == VCHR || vp->v_type == VBLK || vp->v_type == VFIFO)
 		return (EOPNOTSUPP);
 	if ((a_mode & (FREAD | FWRITE | FEXEC)) == 0)
 		return EINVAL;
 
 	fvdat = VTOFUD(vp);
 
 	if (fuse_filehandle_validrw(vp, a_mode, cred, pid)) {
 		fuse_vnode_open(vp, 0, td);
 		return 0;
 	}
 
 	return fuse_filehandle_open(vp, a_mode, NULL, td, cred);
 }
 
 static int
 fuse_vnop_pathconf(struct vop_pathconf_args *ap)
 {
 
 	switch (ap->a_name) {
 	case _PC_FILESIZEBITS:
 		*ap->a_retval = 64;
 		return (0);
 	case _PC_NAME_MAX:
 		*ap->a_retval = NAME_MAX;
 		return (0);
 	case _PC_LINK_MAX:
 		*ap->a_retval = MIN(LONG_MAX, FUSE_LINK_MAX);
 		return (0);
 	case _PC_SYMLINK_MAX:
 		*ap->a_retval = MAXPATHLEN;
 		return (0);
 	case _PC_NO_TRUNC:
 		*ap->a_retval = 1;
 		return (0);
 	default:
 		return (vop_stdpathconf(ap));
 	}
 }
 
 /*
     struct vnop_read_args {
 	struct vnode *a_vp;
 	struct uio *a_uio;
 	int  a_ioflag;
 	struct ucred *a_cred;
     };
 */
 static int
 fuse_vnop_read(struct vop_read_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct uio *uio = ap->a_uio;
 	int ioflag = ap->a_ioflag;
 	struct ucred *cred = ap->a_cred;
 	pid_t pid = curthread->td_proc->p_pid;
 
 	if (fuse_isdeadfs(vp)) {
 		return ENXIO;
 	}
 
 	if (VTOFUD(vp)->flag & FN_DIRECTIO) {
 		ioflag |= IO_DIRECT;
 	}
 
 	return fuse_io_dispatch(vp, uio, ioflag, false, cred, pid);
 }
 
 /*
     struct vnop_readdir_args {
 	struct vnode *a_vp;
 	struct uio *a_uio;
 	struct ucred *a_cred;
 	int *a_eofflag;
 	int *ncookies;
 	u_long **a_cookies;
     };
 */
 static int
 fuse_vnop_readdir(struct vop_readdir_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct uio *uio = ap->a_uio;
 	struct ucred *cred = ap->a_cred;
 	struct fuse_filehandle *fufh = NULL;
 	struct fuse_iov cookediov;
 	int err = 0;
 	pid_t pid = curthread->td_proc->p_pid;
 
 	if (fuse_isdeadfs(vp)) {
 		return ENXIO;
 	}
 	if (				/* XXXIP ((uio_iovcnt(uio) > 1)) || */
 	    (uio_resid(uio) < sizeof(struct dirent))) {
 		return EINVAL;
 	}
 
 	err = fuse_filehandle_get_dir(vp, &fufh, cred, pid);
 	if (err)
 		return (err);
 #define DIRCOOKEDSIZE FUSE_DIRENT_ALIGN(FUSE_NAME_OFFSET + MAXNAMLEN + 1)
 	fiov_init(&cookediov, DIRCOOKEDSIZE);
 
 	err = fuse_internal_readdir(vp, uio, fufh, &cookediov);
 
 	fiov_teardown(&cookediov);
 
 	return err;
 }
 
 /*
     struct vnop_readlink_args {
 	struct vnode *a_vp;
 	struct uio *a_uio;
 	struct ucred *a_cred;
     };
 */
 static int
 fuse_vnop_readlink(struct vop_readlink_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct uio *uio = ap->a_uio;
 	struct ucred *cred = ap->a_cred;
 
 	struct fuse_dispatcher fdi;
 	int err;
 
 	if (fuse_isdeadfs(vp)) {
 		return ENXIO;
 	}
 	if (!vnode_islnk(vp)) {
 		return EINVAL;
 	}
 	fdisp_init(&fdi, 0);
 	err = fdisp_simple_putget_vp(&fdi, FUSE_READLINK, vp, curthread, cred);
 	if (err) {
 		goto out;
 	}
 	if (((char *)fdi.answ)[0] == '/' &&
 	    fuse_get_mpdata(vnode_mount(vp))->dataflags & FSESS_PUSH_SYMLINKS_IN) {
 		char *mpth = vnode_mount(vp)->mnt_stat.f_mntonname;
 
 		err = uiomove(mpth, strlen(mpth), uio);
 	}
 	if (!err) {
 		err = uiomove(fdi.answ, fdi.iosize, uio);
 	}
 out:
 	fdisp_destroy(&fdi);
 	return err;
 }
 
 /*
     struct vnop_reclaim_args {
 	struct vnode *a_vp;
 	struct thread *a_td;
     };
 */
 static int
 fuse_vnop_reclaim(struct vop_reclaim_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct thread *td = ap->a_td;
 	struct fuse_vnode_data *fvdat = VTOFUD(vp);
 	struct fuse_filehandle *fufh, *fufh_tmp;
 
 	if (!fvdat) {
 		panic("FUSE: no vnode data during recycling");
 	}
 	LIST_FOREACH_SAFE(fufh, &fvdat->handles, next, fufh_tmp) {
 		printf("FUSE: vnode being reclaimed with open fufh "
 			"(type=%#x)", fufh->fufh_type);
 		fuse_filehandle_close(vp, fufh, td, NULL);
 	}
 
 	if ((!fuse_isdeadfs(vp)) && (fvdat->nlookup)) {
 		fuse_internal_forget_send(vnode_mount(vp), td, NULL, VTOI(vp),
 		    fvdat->nlookup);
 	}
 	fuse_vnode_setparent(vp, NULL);
 	cache_purge(vp);
 	vfs_hash_remove(vp);
 	vnode_destroy_vobject(vp);
 	fuse_vnode_destroy(vp);
 
 	return 0;
 }
 
 /*
     struct vnop_remove_args {
 	struct vnode *a_dvp;
 	struct vnode *a_vp;
 	struct componentname *a_cnp;
     };
 */
 static int
 fuse_vnop_remove(struct vop_remove_args *ap)
 {
 	struct vnode *dvp = ap->a_dvp;
 	struct vnode *vp = ap->a_vp;
 	struct componentname *cnp = ap->a_cnp;
 
 	int err;
 
 	if (fuse_isdeadfs(vp)) {
 		return ENXIO;
 	}
 	if (vnode_isdir(vp)) {
 		return EPERM;
 	}
 	cache_purge(vp);
 
 	err = fuse_internal_remove(dvp, vp, cnp, FUSE_UNLINK);
 
 	if (err == 0)
 		fuse_internal_vnode_disappear(vp);
 	return err;
 }
 
 /*
     struct vnop_rename_args {
 	struct vnode *a_fdvp;
 	struct vnode *a_fvp;
 	struct componentname *a_fcnp;
 	struct vnode *a_tdvp;
 	struct vnode *a_tvp;
 	struct componentname *a_tcnp;
     };
 */
 static int
 fuse_vnop_rename(struct vop_rename_args *ap)
 {
 	struct vnode *fdvp = ap->a_fdvp;
 	struct vnode *fvp = ap->a_fvp;
 	struct componentname *fcnp = ap->a_fcnp;
 	struct vnode *tdvp = ap->a_tdvp;
 	struct vnode *tvp = ap->a_tvp;
 	struct componentname *tcnp = ap->a_tcnp;
 	struct fuse_data *data;
 
 	int err = 0;
 
 	if (fuse_isdeadfs(fdvp)) {
 		return ENXIO;
 	}
 	if (fvp->v_mount != tdvp->v_mount ||
 	    (tvp && fvp->v_mount != tvp->v_mount)) {
 		SDT_PROBE2(fusefs, , vnops, trace, 1, "cross-device rename");
 		err = EXDEV;
 		goto out;
 	}
 	cache_purge(fvp);
 
 	/*
 	 * FUSE library is expected to check if target directory is not
 	 * under the source directory in the file system tree.
 	 * Linux performs this check at VFS level.
 	 */
 	data = fuse_get_mpdata(vnode_mount(tdvp));
 	sx_xlock(&data->rename_lock);
 	err = fuse_internal_rename(fdvp, fcnp, tdvp, tcnp);
 	if (err == 0) {
 		if (tdvp != fdvp)
 			fuse_vnode_setparent(fvp, tdvp);
 		if (tvp != NULL)
 			fuse_vnode_setparent(tvp, NULL);
 	}
 	sx_unlock(&data->rename_lock);
 
 	if (tvp != NULL && tvp != fvp) {
 		cache_purge(tvp);
 	}
 	if (vnode_isdir(fvp)) {
 		if ((tvp != NULL) && vnode_isdir(tvp)) {
 			cache_purge(tdvp);
 		}
 		cache_purge(fdvp);
 	}
 out:
 	if (tdvp == tvp) {
 		vrele(tdvp);
 	} else {
 		vput(tdvp);
 	}
 	if (tvp != NULL) {
 		vput(tvp);
 	}
 	vrele(fdvp);
 	vrele(fvp);
 
 	return err;
 }
 
 /*
     struct vnop_rmdir_args {
 	    struct vnode *a_dvp;
 	    struct vnode *a_vp;
 	    struct componentname *a_cnp;
     } *ap;
 */
 static int
 fuse_vnop_rmdir(struct vop_rmdir_args *ap)
 {
 	struct vnode *dvp = ap->a_dvp;
 	struct vnode *vp = ap->a_vp;
 
 	int err;
 
 	if (fuse_isdeadfs(vp)) {
 		return ENXIO;
 	}
 	if (VTOFUD(vp) == VTOFUD(dvp)) {
 		return EINVAL;
 	}
 	err = fuse_internal_remove(dvp, vp, ap->a_cnp, FUSE_RMDIR);
 
 	if (err == 0)
 		fuse_internal_vnode_disappear(vp);
 	return err;
 }
 
 /*
     struct vnop_setattr_args {
 	struct vnode *a_vp;
 	struct vattr *a_vap;
 	struct ucred *a_cred;
 	struct thread *a_td;
     };
 */
 static int
 fuse_vnop_setattr(struct vop_setattr_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct vattr *vap = ap->a_vap;
 	struct ucred *cred = ap->a_cred;
 	struct thread *td = curthread;
 	struct mount *mp;
 	struct fuse_data *data;
+	struct vattr old_va;
 	int dataflags;
-	int err = 0;
+	int err = 0, err2;
 	accmode_t accmode = 0;
 	bool checkperm;
+	gid_t cr_gid;
 
 	mp = vnode_mount(vp);
 	data = fuse_get_mpdata(mp);
 	dataflags = data->dataflags;
 	checkperm = dataflags & FSESS_DEFAULT_PERMISSIONS;
+	if (cred->cr_ngroups > 0)
+		cr_gid = cred->cr_groups[0];
+	else
+		cr_gid = 0;
 
 	if (fuse_isdeadfs(vp)) {
 		return ENXIO;
 	}
 
 	if (vap->va_uid != (uid_t)VNOVAL) {
 		if (checkperm) {
 			/* Only root may change a file's owner */
 			err = priv_check_cred(cred, PRIV_VFS_CHOWN);
-			if (err)
-				return err;;
-		}
-		accmode |= VADMIN;
+			if (err) {
+				/* As a special case, allow the null chown */
+				err2 = fuse_internal_getattr(vp, &old_va, cred,
+					td);
+				if (err2)
+					return (err2);
+				if (vap->va_uid != old_va.va_uid)
+					return err;
+				else
+					accmode |= VADMIN;
+			} else
+				accmode |= VADMIN;
+		} else
+			accmode |= VADMIN;
 	}
 	if (vap->va_gid != (gid_t)VNOVAL) {
 		if (checkperm && !groupmember(vap->va_gid, cred))
 		{
 			/*
 			 * Non-root users may only chgrp to one of their own
 			 * groups 
 			 */
 			err = priv_check_cred(cred, PRIV_VFS_CHOWN);
-			if (err)
-				return err;
-		}
-		accmode |= VADMIN;
+			if (err) {
+				/* As a special case, allow the null chgrp */
+				err2 = fuse_internal_getattr(vp, &old_va, cred,
+					td);
+				if (err2)
+					return (err2);
+				if (vap->va_gid != old_va.va_gid)
+					return err;
+				else
+					accmode |= VADMIN;
+			} else
+				accmode |= VADMIN;
+		} else
+			accmode |= VADMIN;
 	}
 	if (vap->va_size != VNOVAL) {
 		switch (vp->v_type) {
 		case VDIR:
 			return (EISDIR);
 		case VLNK:
 		case VREG:
 			if (vfs_isrdonly(mp))
 				return (EROFS);
 			break;
 		default:
 			/*
 			 * According to POSIX, the result is unspecified
 			 * for file types other than regular files,
 			 * directories and shared memory objects.  We
 			 * don't support shared memory objects in the file
 			 * system, and have dubious support for truncating
 			 * symlinks.  Just ignore the request in other cases.
 			 */
 			return (0);
 		}
 		/* Don't set accmode.  Permission to trunc is checked upstack */
 	}
 	/*
 	 * TODO: for atime and mtime, only require VWRITE if UTIMENS_NULL is
 	 * set. PR 237181
 	 */
 	if (vap->va_atime.tv_sec != VNOVAL)
 		accmode |= VADMIN;
 	if (vap->va_mtime.tv_sec != VNOVAL)
 		accmode |= VADMIN;
 	if (vap->va_mode != (mode_t)VNOVAL) {
 		/* Only root may set the sticky bit on non-directories */
 		if (checkperm && vp->v_type != VDIR && (vap->va_mode & S_ISTXT)
 		    && priv_check_cred(cred, PRIV_VFS_STICKYFILE))
 			return EFTYPE;
 		if (checkperm && (vap->va_mode & S_ISGID)) {
-			struct vattr old_va;
 			err = fuse_internal_getattr(vp, &old_va, cred, td);
 			if (err)
 				return (err);
 			if (!groupmember(old_va.va_gid, cred)) {
 				err = priv_check_cred(cred, PRIV_VFS_SETGID);
 				if (err)
 					return (err);
 			}
 		}
 		accmode |= VADMIN;
 	}
 
 	if (vfs_isrdonly(mp))
 		return EROFS;
 
 	err = fuse_internal_access(vp, accmode, td, cred);
 	if (err)
 		return err;
 	else
 		return fuse_internal_setattr(vp, vap, td, cred);
 }
 
 /*
     struct vnop_strategy_args {
 	struct vnode *a_vp;
 	struct buf *a_bp;
     };
 */
 static int
 fuse_vnop_strategy(struct vop_strategy_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct buf *bp = ap->a_bp;
 
 	if (!vp || fuse_isdeadfs(vp)) {
 		bp->b_ioflags |= BIO_ERROR;
 		bp->b_error = ENXIO;
 		bufdone(bp);
 		return 0;
 	}
 	if (bp->b_iocmd == BIO_WRITE) {
 		int err;
 
 		err = fuse_vnode_refreshsize(vp, NOCRED);
 		if (err) {
 			bp->b_ioflags |= BIO_ERROR;
 			bp->b_error = err;
 			bufdone(bp);
 			return 0;
 		}
 	}
 
 	/*
 	 * VOP_STRATEGY always returns zero and signals error via bp->b_ioflags.
 	 * fuse_io_strategy sets bp's error fields
 	 */
 	(void)fuse_io_strategy(vp, bp);
 
 	return 0;
 }
 
 
 /*
     struct vnop_symlink_args {
 	struct vnode *a_dvp;
 	struct vnode **a_vpp;
 	struct componentname *a_cnp;
 	struct vattr *a_vap;
 	char *a_target;
     };
 */
 static int
 fuse_vnop_symlink(struct vop_symlink_args *ap)
 {
 	struct vnode *dvp = ap->a_dvp;
 	struct vnode **vpp = ap->a_vpp;
 	struct componentname *cnp = ap->a_cnp;
 	const char *target = ap->a_target;
 
 	struct fuse_dispatcher fdi;
 
 	int err;
 	size_t len;
 
 	if (fuse_isdeadfs(dvp)) {
 		return ENXIO;
 	}
 	/*
 	 * Unlike the other creator type calls, here we have to create a message
 	 * where the name of the new entry comes first, and the data describing
 	 * the entry comes second.
 	 * Hence we can't rely on our handy fuse_internal_newentry() routine,
 	 * but put together the message manually and just call the core part.
 	 */
 
 	len = strlen(target) + 1;
 	fdisp_init(&fdi, len + cnp->cn_namelen + 1);
 	fdisp_make_vp(&fdi, FUSE_SYMLINK, dvp, curthread, NULL);
 
 	memcpy(fdi.indata, cnp->cn_nameptr, cnp->cn_namelen);
 	((char *)fdi.indata)[cnp->cn_namelen] = '\0';
 	memcpy((char *)fdi.indata + cnp->cn_namelen + 1, target, len);
 
 	err = fuse_internal_newentry_core(dvp, vpp, cnp, VLNK, &fdi);
 	fdisp_destroy(&fdi);
 	return err;
 }
 
 /*
     struct vnop_write_args {
 	struct vnode *a_vp;
 	struct uio *a_uio;
 	int  a_ioflag;
 	struct ucred *a_cred;
     };
 */
 static int
 fuse_vnop_write(struct vop_write_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct uio *uio = ap->a_uio;
 	int ioflag = ap->a_ioflag;
 	struct ucred *cred = ap->a_cred;
 	pid_t pid = curthread->td_proc->p_pid;
 	int err;
 
 	if (fuse_isdeadfs(vp)) {
 		return ENXIO;
 	}
 	err = fuse_vnode_refreshsize(vp, cred);
 	if (err)
 		return err;
 
 	if (VTOFUD(vp)->flag & FN_DIRECTIO) {
 		ioflag |= IO_DIRECT;
 	}
 
 	return fuse_io_dispatch(vp, uio, ioflag, false, cred, pid);
 }
 
 SDT_PROBE_DEFINE1(fusefs, , vnops, vnop_getpages_error, "int");
 /*
     struct vnop_getpages_args {
 	struct vnode *a_vp;
 	vm_page_t *a_m;
 	int a_count;
 	int a_reqpage;
     };
 */
 static int
 fuse_vnop_getpages(struct vop_getpages_args *ap)
 {
 	int i, error, nextoff, size, toff, count, npages;
 	struct uio uio;
 	struct iovec iov;
 	vm_offset_t kva;
 	struct buf *bp;
 	struct vnode *vp;
 	struct thread *td;
 	struct ucred *cred;
 	vm_page_t *pages;
 	pid_t pid = curthread->td_proc->p_pid;
 
 	vp = ap->a_vp;
 	KASSERT(vp->v_object, ("objectless vp passed to getpages"));
 	td = curthread;			/* XXX */
 	cred = curthread->td_ucred;	/* XXX */
 	pages = ap->a_m;
 	npages = ap->a_count;
 
 	if (!fsess_opt_mmap(vnode_mount(vp))) {
 		SDT_PROBE2(fusefs, , vnops, trace, 1,
 			"called on non-cacheable vnode??\n");
 		return (VM_PAGER_ERROR);
 	}
 
 	/*
 	 * If the last page is partially valid, just return it and allow
 	 * the pager to zero-out the blanks.  Partially valid pages can
 	 * only occur at the file EOF.
 	 *
 	 * XXXGL: is that true for FUSE, which is a local filesystem,
 	 * but still somewhat disconnected from the kernel?
 	 */
 	VM_OBJECT_WLOCK(vp->v_object);
 	if (pages[npages - 1]->valid != 0 && --npages == 0)
 		goto out;
 	VM_OBJECT_WUNLOCK(vp->v_object);
 
 	/*
 	 * We use only the kva address for the buffer, but this is extremely
 	 * convenient and fast.
 	 */
 	bp = uma_zalloc(fuse_pbuf_zone, M_WAITOK);
 
 	kva = (vm_offset_t)bp->b_data;
 	pmap_qenter(kva, pages, npages);
 	VM_CNT_INC(v_vnodein);
 	VM_CNT_ADD(v_vnodepgsin, npages);
 
 	count = npages << PAGE_SHIFT;
 	iov.iov_base = (caddr_t)kva;
 	iov.iov_len = count;
 	uio.uio_iov = &iov;
 	uio.uio_iovcnt = 1;
 	uio.uio_offset = IDX_TO_OFF(pages[0]->pindex);
 	uio.uio_resid = count;
 	uio.uio_segflg = UIO_SYSSPACE;
 	uio.uio_rw = UIO_READ;
 	uio.uio_td = td;
 
 	error = fuse_io_dispatch(vp, &uio, IO_DIRECT, true, cred, pid);
 	pmap_qremove(kva, npages);
 
 	uma_zfree(fuse_pbuf_zone, bp);
 
 	if (error && (uio.uio_resid == count)) {
 		SDT_PROBE1(fusefs, , vnops, vnop_getpages_error, error);
 		return VM_PAGER_ERROR;
 	}
 	/*
 	 * Calculate the number of bytes read and validate only that number
 	 * of bytes.  Note that due to pending writes, size may be 0.  This
 	 * does not mean that the remaining data is invalid!
 	 */
 
 	size = count - uio.uio_resid;
 	VM_OBJECT_WLOCK(vp->v_object);
 	fuse_vm_page_lock_queues();
 	for (i = 0, toff = 0; i < npages; i++, toff = nextoff) {
 		vm_page_t m;
 
 		nextoff = toff + PAGE_SIZE;
 		m = pages[i];
 
 		if (nextoff <= size) {
 			/*
 			 * Read operation filled an entire page
 			 */
 			m->valid = VM_PAGE_BITS_ALL;
 			KASSERT(m->dirty == 0,
 			    ("fuse_getpages: page %p is dirty", m));
 		} else if (size > toff) {
 			/*
 			 * Read operation filled a partial page.
 			 */
 			m->valid = 0;
 			vm_page_set_valid_range(m, 0, size - toff);
 			KASSERT(m->dirty == 0,
 			    ("fuse_getpages: page %p is dirty", m));
 		} else {
 			/*
 			 * Read operation was short.  If no error occurred
 			 * we may have hit a zero-fill section.   We simply
 			 * leave valid set to 0.
 			 */
 			;
 		}
 	}
 	fuse_vm_page_unlock_queues();
 out:
 	VM_OBJECT_WUNLOCK(vp->v_object);
 	if (ap->a_rbehind)
 		*ap->a_rbehind = 0;
 	if (ap->a_rahead)
 		*ap->a_rahead = 0;
 	return (VM_PAGER_OK);
 }
 
 /*
     struct vnop_putpages_args {
 	struct vnode *a_vp;
 	vm_page_t *a_m;
 	int a_count;
 	int a_sync;
 	int *a_rtvals;
 	vm_ooffset_t a_offset;
     };
 */
 static int
 fuse_vnop_putpages(struct vop_putpages_args *ap)
 {
 	struct uio uio;
 	struct iovec iov;
 	vm_offset_t kva;
 	struct buf *bp;
 	int i, error, npages, count;
 	off_t offset;
 	int *rtvals;
 	struct vnode *vp;
 	struct thread *td;
 	struct ucred *cred;
 	vm_page_t *pages;
 	vm_ooffset_t fsize;
 	pid_t pid = curthread->td_proc->p_pid;
 
 	vp = ap->a_vp;
 	KASSERT(vp->v_object, ("objectless vp passed to putpages"));
 	fsize = vp->v_object->un_pager.vnp.vnp_size;
 	td = curthread;			/* XXX */
 	cred = curthread->td_ucred;	/* XXX */
 	pages = ap->a_m;
 	count = ap->a_count;
 	rtvals = ap->a_rtvals;
 	npages = btoc(count);
 	offset = IDX_TO_OFF(pages[0]->pindex);
 
 	if (!fsess_opt_mmap(vnode_mount(vp))) {
 		SDT_PROBE2(fusefs, , vnops, trace, 1,
 			"called on non-cacheable vnode??\n");
 	}
 	for (i = 0; i < npages; i++)
 		rtvals[i] = VM_PAGER_AGAIN;
 
 	/*
 	 * When putting pages, do not extend file past EOF.
 	 */
 
 	if (offset + count > fsize) {
 		count = fsize - offset;
 		if (count < 0)
 			count = 0;
 	}
 	/*
 	 * We use only the kva address for the buffer, but this is extremely
 	 * convenient and fast.
 	 */
 	bp = uma_zalloc(fuse_pbuf_zone, M_WAITOK);
 
 	kva = (vm_offset_t)bp->b_data;
 	pmap_qenter(kva, pages, npages);
 	VM_CNT_INC(v_vnodeout);
 	VM_CNT_ADD(v_vnodepgsout, count);
 
 	iov.iov_base = (caddr_t)kva;
 	iov.iov_len = count;
 	uio.uio_iov = &iov;
 	uio.uio_iovcnt = 1;
 	uio.uio_offset = offset;
 	uio.uio_resid = count;
 	uio.uio_segflg = UIO_SYSSPACE;
 	uio.uio_rw = UIO_WRITE;
 	uio.uio_td = td;
 
 	error = fuse_io_dispatch(vp, &uio, IO_DIRECT, true, cred, pid);
 
 	pmap_qremove(kva, npages);
 	uma_zfree(fuse_pbuf_zone, bp);
 
 	if (!error) {
 		int nwritten = round_page(count - uio.uio_resid) / PAGE_SIZE;
 
 		for (i = 0; i < nwritten; i++) {
 			rtvals[i] = VM_PAGER_OK;
 			VM_OBJECT_WLOCK(pages[i]->object);
 			vm_page_undirty(pages[i]);
 			VM_OBJECT_WUNLOCK(pages[i]->object);
 		}
 	}
 	return rtvals[0];
 }
 
 static const char extattr_namespace_separator = '.';
 
 /*
     struct vop_getextattr_args {
 	struct vop_generic_args a_gen;
 	struct vnode *a_vp;
 	int a_attrnamespace;
 	const char *a_name;
 	struct uio *a_uio;
 	size_t *a_size;
 	struct ucred *a_cred;
 	struct thread *a_td;
     };
 */
 static int
 fuse_vnop_getextattr(struct vop_getextattr_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct uio *uio = ap->a_uio;
 	struct fuse_dispatcher fdi;
 	struct fuse_getxattr_in *get_xattr_in;
 	struct fuse_getxattr_out *get_xattr_out;
 	struct mount *mp = vnode_mount(vp);
 	struct thread *td = ap->a_td;
 	struct ucred *cred = ap->a_cred;
 	char *prefix;
 	char *attr_str;
 	size_t len;
 	int err;
 
 	if (fuse_isdeadfs(vp))
 		return (ENXIO);
 
 	if (!fsess_isimpl(mp, FUSE_GETXATTR))
 		return EOPNOTSUPP;
 
 	err = fuse_extattr_check_cred(vp, ap->a_attrnamespace, cred, td, VREAD);
 	if (err)
 		return err;
 
 	/* Default to looking for user attributes. */
 	if (ap->a_attrnamespace == EXTATTR_NAMESPACE_SYSTEM)
 		prefix = EXTATTR_NAMESPACE_SYSTEM_STRING;
 	else
 		prefix = EXTATTR_NAMESPACE_USER_STRING;
 
 	len = strlen(prefix) + sizeof(extattr_namespace_separator) +
 	    strlen(ap->a_name) + 1;
 
 	fdisp_init(&fdi, len + sizeof(*get_xattr_in));
 	fdisp_make_vp(&fdi, FUSE_GETXATTR, vp, td, cred);
 
 	get_xattr_in = fdi.indata;
 	/*
 	 * Check to see whether we're querying the available size or
 	 * issuing the actual request.  If we pass in 0, we get back struct
 	 * fuse_getxattr_out.  If we pass in a non-zero size, we get back
 	 * that much data, without the struct fuse_getxattr_out header.
 	 */
 	if (uio == NULL)
 		get_xattr_in->size = 0;
 	else
 		get_xattr_in->size = uio->uio_resid;
 
 	attr_str = (char *)fdi.indata + sizeof(*get_xattr_in);
 	snprintf(attr_str, len, "%s%c%s", prefix, extattr_namespace_separator,
 	    ap->a_name);
 
 	err = fdisp_wait_answ(&fdi);
 	if (err != 0) {
 		if (err == ENOSYS) {
 			fsess_set_notimpl(mp, FUSE_GETXATTR);
 			err = EOPNOTSUPP;
 		}
 		goto out;
 	}
 
 	get_xattr_out = fdi.answ;
 
 	if (ap->a_size != NULL)
 		*ap->a_size = get_xattr_out->size;
 
 	if (uio != NULL)
 		err = uiomove(fdi.answ, fdi.iosize, uio);
 
 out:
 	fdisp_destroy(&fdi);
 	return (err);
 }
 
 /*
     struct vop_setextattr_args {
 	struct vop_generic_args a_gen;
 	struct vnode *a_vp;
 	int a_attrnamespace;
 	const char *a_name;
 	struct uio *a_uio;
 	struct ucred *a_cred;
 	struct thread *a_td;
     };
 */
 static int
 fuse_vnop_setextattr(struct vop_setextattr_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct uio *uio = ap->a_uio;
 	struct fuse_dispatcher fdi;
 	struct fuse_setxattr_in *set_xattr_in;
 	struct mount *mp = vnode_mount(vp);
 	struct thread *td = ap->a_td;
 	struct ucred *cred = ap->a_cred;
 	char *prefix;
 	size_t len;
 	char *attr_str;
 	int err;
 	
 	if (fuse_isdeadfs(vp))
 		return (ENXIO);
 
 	if (!fsess_isimpl(mp, FUSE_SETXATTR))
 		return EOPNOTSUPP;
 
 	if (vfs_isrdonly(mp))
 		return EROFS;
 
 	/* Deleting xattrs must use VOP_DELETEEXTATTR instead */
 	if (ap->a_uio == NULL) {
 		/*
 		 * If we got here as fallback from VOP_DELETEEXTATTR, then
 		 * return EOPNOTSUPP.
 		 */
 		if (!fsess_isimpl(mp, FUSE_REMOVEXATTR))
 			return (EOPNOTSUPP);
 		else
 			return (EINVAL);
 	}
 
 	err = fuse_extattr_check_cred(vp, ap->a_attrnamespace, cred, td,
 		VWRITE);
 	if (err)
 		return err;
 
 	/* Default to looking for user attributes. */
 	if (ap->a_attrnamespace == EXTATTR_NAMESPACE_SYSTEM)
 		prefix = EXTATTR_NAMESPACE_SYSTEM_STRING;
 	else
 		prefix = EXTATTR_NAMESPACE_USER_STRING;
 
 	len = strlen(prefix) + sizeof(extattr_namespace_separator) +
 	    strlen(ap->a_name) + 1;
 
 	fdisp_init(&fdi, len + sizeof(*set_xattr_in) + uio->uio_resid);
 	fdisp_make_vp(&fdi, FUSE_SETXATTR, vp, td, cred);
 
 	set_xattr_in = fdi.indata;
 	set_xattr_in->size = uio->uio_resid;
 
 	attr_str = (char *)fdi.indata + sizeof(*set_xattr_in);
 	snprintf(attr_str, len, "%s%c%s", prefix, extattr_namespace_separator,
 	    ap->a_name);
 
 	err = uiomove((char *)fdi.indata + sizeof(*set_xattr_in) + len,
 	    uio->uio_resid, uio);
 	if (err != 0) {
 		goto out;
 	}
 
 	err = fdisp_wait_answ(&fdi);
 
 	if (err == ENOSYS) {
 		fsess_set_notimpl(mp, FUSE_SETXATTR);
 		err = EOPNOTSUPP;
 	}
 	if (err == ERESTART) {
 		/* Can't restart after calling uiomove */
 		err = EINTR;
 	}
 
 out:
 	fdisp_destroy(&fdi);
 	return (err);
 }
 
 /*
  * The Linux / FUSE extended attribute list is simply a collection of
  * NUL-terminated strings.  The FreeBSD extended attribute list is a single
  * byte length followed by a non-NUL terminated string.  So, this allows
  * conversion of the Linux / FUSE format to the FreeBSD format in place.
  * Linux attribute names are reported with the namespace as a prefix (e.g.
  * "user.attribute_name"), but in FreeBSD they are reported without the
  * namespace prefix (e.g. "attribute_name").  So, we're going from:
  *
  * user.attr_name1\0user.attr_name2\0
  *
  * to:
  *
  * <num>attr_name1<num>attr_name2
  *
  * Where "<num>" is a single byte number of characters in the attribute name.
  * 
  * Args:
  * prefix - exattr namespace prefix string
  * list, list_len - input list with namespace prefixes
  * bsd_list, bsd_list_len - output list compatible with bsd vfs
  */
 static int
 fuse_xattrlist_convert(char *prefix, const char *list, int list_len,
     char *bsd_list, int *bsd_list_len)
 {
 	int len, pos, dist_to_next, prefix_len;
 
 	pos = 0;
 	*bsd_list_len = 0;
 	prefix_len = strlen(prefix);
 
 	while (pos < list_len && list[pos] != '\0') {
 		dist_to_next = strlen(&list[pos]) + 1;
 		if (bcmp(&list[pos], prefix, prefix_len) == 0 &&
 		    list[pos + prefix_len] == extattr_namespace_separator) {
 			len = dist_to_next -
 			    (prefix_len + sizeof(extattr_namespace_separator)) - 1;
 			if (len >= EXTATTR_MAXNAMELEN)
 				return (ENAMETOOLONG);
 
 			bsd_list[*bsd_list_len] = len;
 			memcpy(&bsd_list[*bsd_list_len + 1],
 			    &list[pos + prefix_len +
 			    sizeof(extattr_namespace_separator)], len);
 
 			*bsd_list_len += len + 1;
 		}
 
 		pos += dist_to_next;
 	}
 
 	return (0);
 }
 
 /*
     struct vop_listextattr_args {
 	struct vop_generic_args a_gen;
 	struct vnode *a_vp;
 	int a_attrnamespace;
 	struct uio *a_uio;
 	size_t *a_size;
 	struct ucred *a_cred;
 	struct thread *a_td;
     };
 */
 static int
 fuse_vnop_listextattr(struct vop_listextattr_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct uio *uio = ap->a_uio;
 	struct fuse_dispatcher fdi;
 	struct fuse_listxattr_in *list_xattr_in;
 	struct fuse_listxattr_out *list_xattr_out;
 	struct mount *mp = vnode_mount(vp);
 	struct thread *td = ap->a_td;
 	struct ucred *cred = ap->a_cred;
 	size_t len;
 	char *prefix;
 	char *attr_str;
 	char *bsd_list = NULL;
 	char *linux_list;
 	int bsd_list_len;
 	int linux_list_len;
 	int err;
 
 	if (fuse_isdeadfs(vp))
 		return (ENXIO);
 
 	if (!fsess_isimpl(mp, FUSE_LISTXATTR))
 		return EOPNOTSUPP;
 
 	err = fuse_extattr_check_cred(vp, ap->a_attrnamespace, cred, td, VREAD);
 	if (err)
 		return err;
 
 	/*
 	 * Add space for a NUL and the period separator if enabled.
 	 * Default to looking for user attributes.
 	 */
 	if (ap->a_attrnamespace == EXTATTR_NAMESPACE_SYSTEM)
 		prefix = EXTATTR_NAMESPACE_SYSTEM_STRING;
 	else
 		prefix = EXTATTR_NAMESPACE_USER_STRING;
 
 	len = strlen(prefix) + sizeof(extattr_namespace_separator) + 1;
 
 	fdisp_init(&fdi, sizeof(*list_xattr_in) + len);
 	fdisp_make_vp(&fdi, FUSE_LISTXATTR, vp, td, cred);
 
 	/*
 	 * Retrieve Linux / FUSE compatible list size.
 	 */
 	list_xattr_in = fdi.indata;
 	list_xattr_in->size = 0;
 	attr_str = (char *)fdi.indata + sizeof(*list_xattr_in);
 	snprintf(attr_str, len, "%s%c", prefix, extattr_namespace_separator);
 
 	err = fdisp_wait_answ(&fdi);
 	if (err != 0) {
 		if (err == ENOSYS) {
 			fsess_set_notimpl(mp, FUSE_LISTXATTR);
 			err = EOPNOTSUPP;
 		}
 		goto out;
 	}
 
 	list_xattr_out = fdi.answ;
 	linux_list_len = list_xattr_out->size;
 	if (linux_list_len == 0) {
 		if (ap->a_size != NULL)
 			*ap->a_size = linux_list_len;
 		goto out;
 	}
 
 	/*
 	 * Retrieve Linux / FUSE compatible list values.
 	 */
 	fdisp_refresh_vp(&fdi, FUSE_LISTXATTR, vp, td, cred);
 	list_xattr_in = fdi.indata;
 	list_xattr_in->size = linux_list_len + sizeof(*list_xattr_out);
 	list_xattr_in->flags = 0;
 	attr_str = (char *)fdi.indata + sizeof(*list_xattr_in);
 	snprintf(attr_str, len, "%s%c", prefix, extattr_namespace_separator);
 
 	err = fdisp_wait_answ(&fdi);
 	if (err != 0)
 		goto out;
 
 	linux_list = fdi.answ;
 	linux_list_len = fdi.iosize;
 
 	/*
 	 * Retrieve the BSD compatible list values.
 	 * The Linux / FUSE attribute list format isn't the same
 	 * as FreeBSD's format. So we need to transform it into
 	 * FreeBSD's format before giving it to the user.
 	 */
 	bsd_list = malloc(linux_list_len, M_TEMP, M_WAITOK);
 	err = fuse_xattrlist_convert(prefix, linux_list, linux_list_len,
 	    bsd_list, &bsd_list_len);
 	if (err != 0)
 		goto out;
 
 	if (ap->a_size != NULL)
 		*ap->a_size = bsd_list_len;
 
 	if (uio != NULL)
 		err = uiomove(bsd_list, bsd_list_len, uio);
 
 out:
 	free(bsd_list, M_TEMP);
 	fdisp_destroy(&fdi);
 	return (err);
 }
 
 /*
     struct vop_deleteextattr_args {
 	struct vop_generic_args a_gen;
 	struct vnode *a_vp;
 	int a_attrnamespace;
 	const char *a_name;
 	struct ucred *a_cred;
 	struct thread *a_td;
     };
 */
 static int
 fuse_vnop_deleteextattr(struct vop_deleteextattr_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct fuse_dispatcher fdi;
 	struct mount *mp = vnode_mount(vp);
 	struct thread *td = ap->a_td;
 	struct ucred *cred = ap->a_cred;
 	char *prefix;
 	size_t len;
 	char *attr_str;
 	int err;
 
 	if (fuse_isdeadfs(vp))
 		return (ENXIO);
 
 	if (!fsess_isimpl(mp, FUSE_REMOVEXATTR))
 		return EOPNOTSUPP;
 
 	if (vfs_isrdonly(mp))
 		return EROFS;
 
 	err = fuse_extattr_check_cred(vp, ap->a_attrnamespace, cred, td,
 		VWRITE);
 	if (err)
 		return err;
 
 	/* Default to looking for user attributes. */
 	if (ap->a_attrnamespace == EXTATTR_NAMESPACE_SYSTEM)
 		prefix = EXTATTR_NAMESPACE_SYSTEM_STRING;
 	else
 		prefix = EXTATTR_NAMESPACE_USER_STRING;
 
 	len = strlen(prefix) + sizeof(extattr_namespace_separator) +
 	    strlen(ap->a_name) + 1;
 
 	fdisp_init(&fdi, len);
 	fdisp_make_vp(&fdi, FUSE_REMOVEXATTR, vp, td, cred);
 
 	attr_str = fdi.indata;
 	snprintf(attr_str, len, "%s%c%s", prefix, extattr_namespace_separator,
 	    ap->a_name);
 
 	err = fdisp_wait_answ(&fdi);
 	if (err == ENOSYS) {
 		fsess_set_notimpl(mp, FUSE_REMOVEXATTR);
 		err = EOPNOTSUPP;
 	}
 
 	fdisp_destroy(&fdi);
 	return (err);
 }
 
 /*
     struct vnop_print_args {
 	struct vnode *a_vp;
     };
 */
 static int
 fuse_vnop_print(struct vop_print_args *ap)
 {
 	struct fuse_vnode_data *fvdat = VTOFUD(ap->a_vp);
 
 	printf("nodeid: %ju, parent nodeid: %ju, nlookup: %ju, flag: %#x\n",
 	    (uintmax_t)VTOILLU(ap->a_vp), (uintmax_t)fvdat->parent_nid,
 	    (uintmax_t)fvdat->nlookup,
 	    fvdat->flag);
 
 	return 0;
 }
Index: projects/fuse2/tests/sys/fs/fusefs/default_permissions.cc
===================================================================
--- projects/fuse2/tests/sys/fs/fusefs/default_permissions.cc	(revision 347216)
+++ projects/fuse2/tests/sys/fs/fusefs/default_permissions.cc	(revision 347217)
@@ -1,1075 +1,1098 @@
 /*-
  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
  *
  * Copyright (c) 2019 The FreeBSD Foundation
  *
  * This software was developed by BFF Storage Systems, LLC under sponsorship
  * from the FreeBSD Foundation.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
 
 /*
  * Tests for the "default_permissions" mount option.  They must be in their own
  * file so they can be run as an unprivileged user
  */
 
 extern "C" {
 #include <sys/types.h>
 #include <sys/extattr.h>
 
 #include <fcntl.h>
 #include <unistd.h>
 }
 
 #include "mockfs.hh"
 #include "utils.hh"
 
 using namespace testing;
 
 class DefaultPermissions: public FuseTest {
 
 virtual void SetUp() {
 	m_default_permissions = true;
 	FuseTest::SetUp();
 	if (HasFatalFailure() || IsSkipped())
 		return;
 
 	if (geteuid() == 0) {
 		GTEST_SKIP() << "This test requires an unprivileged user";
 	}
 	
 	/* With -o default_permissions, FUSE_ACCESS should never be called */
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([=](auto in) {
 			return (in->header.opcode == FUSE_ACCESS);
 		}, Eq(true)),
 		_)
 	).Times(0);
 }
 
 public:
 void expect_chmod(uint64_t ino, mode_t mode)
 {
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([=](auto in) {
 			return (in->header.opcode == FUSE_SETATTR &&
 				in->header.nodeid == ino &&
 				in->body.setattr.valid == FATTR_MODE &&
 				in->body.setattr.mode == mode);
 		}, Eq(true)),
 		_)
 	).WillOnce(Invoke(ReturnImmediate([=](auto in __unused, auto out) {
 		SET_OUT_HEADER_LEN(out, attr);
 		out->body.attr.attr.ino = ino;	// Must match nodeid
 		out->body.attr.attr.mode = S_IFREG | mode;
 		out->body.attr.attr_valid = UINT64_MAX;
 	})));
 }
 
 void expect_create(const char *relpath, uint64_t ino)
 {
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([=](auto in) {
 			const char *name = (const char*)in->body.bytes +
 				sizeof(fuse_open_in);
 			return (in->header.opcode == FUSE_CREATE &&
 				(0 == strcmp(relpath, name)));
 		}, Eq(true)),
 		_)
 	).WillOnce(Invoke(ReturnImmediate([=](auto in __unused, auto out) {
 		SET_OUT_HEADER_LEN(out, create);
 		out->body.create.entry.attr.mode = S_IFREG | 0644;
 		out->body.create.entry.nodeid = ino;
 		out->body.create.entry.entry_valid = UINT64_MAX;
 		out->body.create.entry.attr_valid = UINT64_MAX;
 	})));
 }
 
 void expect_getattr(uint64_t ino, mode_t mode, uint64_t attr_valid, int times,
 	uid_t uid = 0, gid_t gid = 0)
 {
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([=](auto in) {
 			return (in->header.opcode == FUSE_GETATTR &&
 				in->header.nodeid == ino);
 		}, Eq(true)),
 		_)
 	).Times(times)
 	.WillRepeatedly(Invoke(ReturnImmediate([=](auto i __unused, auto out) {
 		SET_OUT_HEADER_LEN(out, attr);
 		out->body.attr.attr.ino = ino;	// Must match nodeid
 		out->body.attr.attr.mode = mode;
 		out->body.attr.attr.size = 0;
 		out->body.attr.attr.uid = uid;
 		out->body.attr.attr.uid = gid;
 		out->body.attr.attr_valid = attr_valid;
 	})));
 }
 
 void expect_lookup(const char *relpath, uint64_t ino, mode_t mode,
 	uint64_t attr_valid, uid_t uid = 0, gid_t gid = 0)
 {
 	FuseTest::expect_lookup(relpath, ino, mode, 0, 1, attr_valid, uid, gid);
 }
 
 };
 
 class Access: public DefaultPermissions {};
 class Chown: public DefaultPermissions {};
 class Chgrp: public DefaultPermissions {};
 class Lookup: public DefaultPermissions {};
 class Open: public DefaultPermissions {};
 class Setattr: public DefaultPermissions {};
 class Unlink: public DefaultPermissions {};
 class Write: public DefaultPermissions {};
 
 /* 
  * Test permission handling during create, mkdir, mknod, link, symlink, and
  * rename vops (they all share a common path for permission checks in
  * VOP_LOOKUP)
  */
 class Create: public DefaultPermissions {};
 
 class Deleteextattr: public DefaultPermissions {
 public:
 void expect_removexattr()
 {
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([=](auto in) {
 			return (in->header.opcode == FUSE_REMOVEXATTR);
 		}, Eq(true)),
 		_)
 	).WillOnce(Invoke(ReturnErrno(0)));
 }
 };
 
 class Getextattr: public DefaultPermissions {
 public:
 void expect_getxattr(ProcessMockerT r)
 {
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([=](auto in) {
 			return (in->header.opcode == FUSE_GETXATTR);
 		}, Eq(true)),
 		_)
 	).WillOnce(Invoke(r));
 }
 };
 
 class Listextattr: public DefaultPermissions {
 public:
 void expect_listxattr()
 {
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([=](auto in) {
 			return (in->header.opcode == FUSE_LISTXATTR);
 		}, Eq(true)),
 		_)
 	).WillOnce(Invoke(ReturnImmediate([](auto i __unused, auto out) {
 		out->body.listxattr.size = 0;
 		SET_OUT_HEADER_LEN(out, listxattr);
 	})));
 }
 };
 
 class Rename: public DefaultPermissions {
 public:
 	/* 
 	 * Expect a rename and respond with the given error.  Don't both to
 	 * validate arguments; the tests in rename.cc do that.
 	 */
 	void expect_rename(int error)
 	{
 		EXPECT_CALL(*m_mock, process(
 			ResultOf([=](auto in) {
 				return (in->header.opcode == FUSE_RENAME);
 			}, Eq(true)),
 			_)
 		).WillOnce(Invoke(ReturnErrno(error)));
 	}
 };
 
 class Setextattr: public DefaultPermissions {
 public:
 void expect_setxattr(int error)
 {
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([=](auto in) {
 			return (in->header.opcode == FUSE_SETXATTR);
 		}, Eq(true)),
 		_)
 	).WillOnce(Invoke(ReturnErrno(error)));
 }
 };
 
 /* Return a group to which this user does not belong */
 static gid_t excluded_group()
 {
 	int i, ngroups = 64;
 	gid_t newgid, groups[ngroups];
 
 	getgrouplist(getlogin(), getegid(), groups, &ngroups);
 	for (newgid = 0; newgid >= 0; newgid++) {
 		bool belongs = false;
 
 		for (i = 0; i < ngroups; i++) {
 			if (groups[i] == newgid)
 				belongs = true;
 		}
 		if (!belongs)
 			break;
 	}
 	/* newgid is now a group to which the current user does not belong */
 	return newgid;
 }
 
 TEST_F(Access, eacces)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	mode_t	access_mode = X_OK;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0644, UINT64_MAX);
 
 	ASSERT_NE(0, access(FULLPATH, access_mode));
 	ASSERT_EQ(EACCES, errno);
 }
 
 TEST_F(Access, eacces_no_cached_attrs)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	mode_t	access_mode = X_OK;
 
 	expect_getattr(1, S_IFDIR | 0755, 0, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0644, 0);
 	expect_getattr(ino, S_IFREG | 0644, 0, 1);
 	/* 
 	 * Once default_permissions is properly implemented, there might be
 	 * another FUSE_GETATTR or something in here.  But there should not be
 	 * a FUSE_ACCESS
 	 */
 
 	ASSERT_NE(0, access(FULLPATH, access_mode));
 	ASSERT_EQ(EACCES, errno);
 }
 
 TEST_F(Access, ok)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	mode_t	access_mode = R_OK;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0644, UINT64_MAX);
 	/* 
 	 * Once default_permissions is properly implemented, there might be
 	 * another FUSE_GETATTR or something in here.
 	 */
 
 	ASSERT_EQ(0, access(FULLPATH, access_mode)) << strerror(errno);
 }
 
+/* Unprivileged users may chown a file to their own uid */
+TEST_F(Chown, chown_to_self)
+{
+	const char FULLPATH[] = "mountpoint/some_file.txt";
+	const char RELPATH[] = "some_file.txt";
+	const uint64_t ino = 42;
+	const mode_t mode = 0755;
+	uid_t uid;
+
+	uid = geteuid();
+
+	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1, uid);
+	expect_lookup(RELPATH, ino, S_IFREG | mode, UINT64_MAX, uid);
+	/* The OS may optimize chown by omitting the redundant setattr */
+	EXPECT_CALL(*m_mock, process(
+		ResultOf([](auto in) {
+			return (in->header.opcode == FUSE_SETATTR);
+		}, Eq(true)),
+		_)
+	).WillRepeatedly(Invoke(ReturnImmediate([=](auto in __unused, auto out){
+		SET_OUT_HEADER_LEN(out, attr);
+		out->body.attr.attr.mode = S_IFREG | mode;
+		out->body.attr.attr.uid = uid;
+	})));
+
+	EXPECT_EQ(0, chown(FULLPATH, uid, -1)) << strerror(errno);
+}
+
 /* Only root may change a file's owner */
 TEST_F(Chown, eperm)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	const uint64_t ino = 42;
 	const mode_t mode = 0755;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1, geteuid());
 	expect_lookup(RELPATH, ino, S_IFREG | mode, UINT64_MAX, geteuid());
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([](auto in) {
 			return (in->header.opcode == FUSE_SETATTR);
 		}, Eq(true)),
 		_)
 	).Times(0);
 
 	EXPECT_NE(0, chown(FULLPATH, 0, -1));
 	EXPECT_EQ(EPERM, errno);
 }
 
 /* non-root users may only chgrp a file to a group they belong to */
 TEST_F(Chgrp, eperm)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	const uint64_t ino = 42;
 	const mode_t mode = 0755;
 	uid_t uid;
 	gid_t gid, newgid;
 
 	uid = geteuid();
 	gid = getegid();
 	newgid = excluded_group();
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1, uid, gid);
 	expect_lookup(RELPATH, ino, S_IFREG | mode, UINT64_MAX, uid, gid);
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([](auto in) {
 			return (in->header.opcode == FUSE_SETATTR);
 		}, Eq(true)),
 		_)
 	).Times(0);
 
 	EXPECT_NE(0, chown(FULLPATH, -1, newgid));
 	EXPECT_EQ(EPERM, errno);
 }
 
 TEST_F(Chgrp, ok)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	const uint64_t ino = 42;
 	const mode_t mode = 0755;
 	uid_t uid;
 	gid_t gid, newgid;
 
 	uid = geteuid();
 	gid = 0;
 	newgid = getegid();
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1, uid, gid);
 	expect_lookup(RELPATH, ino, S_IFREG | mode, UINT64_MAX, uid, gid);
+	/* The OS may optimize chgrp by omitting the redundant setattr */
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([](auto in) {
-			return (in->header.opcode == FUSE_SETATTR);
-		}, Eq(true)),
-		_)
-	).Times(0);
-	EXPECT_CALL(*m_mock, process(
-		ResultOf([](auto in) {
 			return (in->header.opcode == FUSE_SETATTR &&
 				in->header.nodeid == ino);
 		}, Eq(true)),
 		_)
-	).WillOnce(Invoke(ReturnImmediate([=](auto in __unused, auto out) {
+	).WillRepeatedly(Invoke(ReturnImmediate([=](auto in __unused, auto out){
 		SET_OUT_HEADER_LEN(out, attr);
 		out->body.attr.attr.mode = S_IFREG | mode;
 		out->body.attr.attr.uid = uid;
 		out->body.attr.attr.gid = newgid;
 	})));
 
 	EXPECT_EQ(0, chown(FULLPATH, -1, newgid)) << strerror(errno);
 }
 
 TEST_F(Create, ok)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	int fd;
 
 	expect_getattr(1, S_IFDIR | 0777, UINT64_MAX, 1);
 	EXPECT_LOOKUP(1, RELPATH).WillOnce(Invoke(ReturnErrno(ENOENT)));
 	expect_create(RELPATH, ino);
 
 	fd = open(FULLPATH, O_CREAT | O_EXCL, 0644);
 	EXPECT_LE(0, fd) << strerror(errno);
 	/* Deliberately leak fd.  close(2) will be tested in release.cc */
 }
 
 TEST_F(Create, eacces)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	EXPECT_LOOKUP(1, RELPATH).WillOnce(Invoke(ReturnErrno(ENOENT)));
 
 	EXPECT_EQ(-1, open(FULLPATH, O_CREAT | O_EXCL, 0644));
 	EXPECT_EQ(EACCES, errno);
 }
 
 TEST_F(Deleteextattr, eacces)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	int ns = EXTATTR_NAMESPACE_USER;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0644, UINT64_MAX, 0);
 
 	ASSERT_EQ(-1, extattr_delete_file(FULLPATH, ns, "foo"));
 	ASSERT_EQ(EACCES, errno);
 }
 
 TEST_F(Deleteextattr, ok)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	int ns = EXTATTR_NAMESPACE_USER;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0644, UINT64_MAX, geteuid());
 	expect_removexattr();
 
 	ASSERT_EQ(0, extattr_delete_file(FULLPATH, ns, "foo"))
 		<< strerror(errno);
 }
 
 /* Delete system attributes requires superuser privilege */
 TEST_F(Deleteextattr, system)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	int ns = EXTATTR_NAMESPACE_SYSTEM;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0666, UINT64_MAX, geteuid());
 
 	ASSERT_EQ(-1, extattr_delete_file(FULLPATH, ns, "foo"));
 	ASSERT_EQ(EPERM, errno);
 }
 
 /* Deleting user attributes merely requires WRITE privilege */
 TEST_F(Deleteextattr, user)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	int ns = EXTATTR_NAMESPACE_USER;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0666, UINT64_MAX, 0);
 	expect_removexattr();
 
 	ASSERT_EQ(0, extattr_delete_file(FULLPATH, ns, "foo"))
 		<< strerror(errno);
 }
 
 TEST_F(Getextattr, eacces)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	char data[80];
 	int ns = EXTATTR_NAMESPACE_USER;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0600, UINT64_MAX, 0);
 
 	ASSERT_EQ(-1,
 		extattr_get_file(FULLPATH, ns, "foo", data, sizeof(data)));
 	ASSERT_EQ(EACCES, errno);
 }
 
 TEST_F(Getextattr, ok)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	char data[80];
 	const char value[] = "whatever";
 	ssize_t value_len = strlen(value) + 1;
 	int ns = EXTATTR_NAMESPACE_USER;
 	ssize_t r;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	/* Getting user attributes only requires read access */
 	expect_lookup(RELPATH, ino, S_IFREG | 0444, UINT64_MAX, 0);
 	expect_getxattr(
 		ReturnImmediate([&](auto in __unused, auto out) {
 			memcpy((void*)out->body.bytes, value, value_len);
 			out->header.len = sizeof(out->header) + value_len;
 		})
 	);
 
 	r = extattr_get_file(FULLPATH, ns, "foo", data, sizeof(data));
 	ASSERT_EQ(value_len, r)  << strerror(errno);
 	EXPECT_STREQ(value, data);
 }
 
 /* Getting system attributes requires superuser privileges */
 TEST_F(Getextattr, system)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	char data[80];
 	int ns = EXTATTR_NAMESPACE_SYSTEM;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0666, UINT64_MAX, geteuid());
 
 	ASSERT_EQ(-1,
 		extattr_get_file(FULLPATH, ns, "foo", data, sizeof(data)));
 	ASSERT_EQ(EPERM, errno);
 }
 
 TEST_F(Listextattr, eacces)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	int ns = EXTATTR_NAMESPACE_USER;
 
 	expect_getattr(1, S_IFDIR | 0777, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0600, UINT64_MAX, 0);
 
 	ASSERT_EQ(-1, extattr_list_file(FULLPATH, ns, NULL, 0));
 	ASSERT_EQ(EACCES, errno);
 }
 
 TEST_F(Listextattr, ok)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	int ns = EXTATTR_NAMESPACE_USER;
 
 	expect_getattr(1, S_IFDIR | 0777, UINT64_MAX, 1);
 	/* Listing user extended attributes merely requires read access */
 	expect_lookup(RELPATH, ino, S_IFREG | 0644, UINT64_MAX, 0);
 	expect_listxattr();
 
 	ASSERT_EQ(0, extattr_list_file(FULLPATH, ns, NULL, 0))
 		<< strerror(errno);
 }
 
 /* Listing system xattrs requires superuser privileges */
 TEST_F(Listextattr, system)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	int ns = EXTATTR_NAMESPACE_SYSTEM;
 
 	expect_getattr(1, S_IFDIR | 0777, UINT64_MAX, 1);
 	/* Listing user extended attributes merely requires read access */
 	expect_lookup(RELPATH, ino, S_IFREG | 0644, UINT64_MAX, geteuid());
 
 	ASSERT_EQ(-1, extattr_list_file(FULLPATH, ns, NULL, 0));
 	ASSERT_EQ(EPERM, errno);
 }
 
 /* A component of the search path lacks execute permissions */
 TEST_F(Lookup, eacces)
 {
 	const char FULLPATH[] = "mountpoint/some_dir/some_file.txt";
 	const char RELDIRPATH[] = "some_dir";
 	uint64_t dir_ino = 42;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELDIRPATH, dir_ino, S_IFDIR | 0700, UINT64_MAX, 0);
 
 	EXPECT_EQ(-1, access(FULLPATH, F_OK));
 	EXPECT_EQ(EACCES, errno);
 }
 
 TEST_F(Open, eacces)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0644, UINT64_MAX);
 
 	EXPECT_NE(0, open(FULLPATH, O_RDWR));
 	EXPECT_EQ(EACCES, errno);
 }
 
 TEST_F(Open, ok)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	int fd;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0644, UINT64_MAX);
 	expect_open(ino, 0, 1);
 
 	fd = open(FULLPATH, O_RDONLY);
 	EXPECT_LE(0, fd) << strerror(errno);
 	/* Deliberately leak fd.  close(2) will be tested in release.cc */
 }
 
 TEST_F(Rename, eacces_on_srcdir)
 {
 	const char FULLDST[] = "mountpoint/d/dst";
 	const char RELDST[] = "d/dst";
 	const char FULLSRC[] = "mountpoint/src";
 	const char RELSRC[] = "src";
 	uint64_t ino = 42;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1, 0);
 	expect_lookup(RELSRC, ino, S_IFREG | 0644, UINT64_MAX);
 	EXPECT_LOOKUP(1, RELDST)
 		.Times(AnyNumber())
 		.WillRepeatedly(Invoke(ReturnErrno(ENOENT)));
 
 	ASSERT_EQ(-1, rename(FULLSRC, FULLDST));
 	ASSERT_EQ(EACCES, errno);
 }
 
 TEST_F(Rename, eacces_on_dstdir_for_creating)
 {
 	const char FULLDST[] = "mountpoint/d/dst";
 	const char RELDSTDIR[] = "d";
 	const char RELDST[] = "dst";
 	const char FULLSRC[] = "mountpoint/src";
 	const char RELSRC[] = "src";
 	uint64_t src_ino = 42;
 	uint64_t dstdir_ino = 43;
 
 	expect_getattr(1, S_IFDIR | 0777, UINT64_MAX, 1, 0);
 	expect_lookup(RELSRC, src_ino, S_IFREG | 0644, UINT64_MAX);
 	expect_lookup(RELDSTDIR, dstdir_ino, S_IFDIR | 0755, UINT64_MAX);
 	EXPECT_LOOKUP(dstdir_ino, RELDST).WillOnce(Invoke(ReturnErrno(ENOENT)));
 
 	ASSERT_EQ(-1, rename(FULLSRC, FULLDST));
 	ASSERT_EQ(EACCES, errno);
 }
 
 TEST_F(Rename, eacces_on_dstdir_for_removing)
 {
 	const char FULLDST[] = "mountpoint/d/dst";
 	const char RELDSTDIR[] = "d";
 	const char RELDST[] = "dst";
 	const char FULLSRC[] = "mountpoint/src";
 	const char RELSRC[] = "src";
 	uint64_t src_ino = 42;
 	uint64_t dstdir_ino = 43;
 
 	expect_getattr(1, S_IFDIR | 0777, UINT64_MAX, 1, 0);
 	expect_lookup(RELSRC, src_ino, S_IFREG | 0644, UINT64_MAX);
 	expect_lookup(RELDSTDIR, dstdir_ino, S_IFDIR | 0755, UINT64_MAX);
 	EXPECT_LOOKUP(dstdir_ino, RELDST).WillOnce(Invoke(ReturnErrno(ENOENT)));
 
 	ASSERT_EQ(-1, rename(FULLSRC, FULLDST));
 	ASSERT_EQ(EACCES, errno);
 }
 
 TEST_F(Rename, eperm_on_sticky_srcdir)
 {
 	const char FULLDST[] = "mountpoint/d/dst";
 	const char FULLSRC[] = "mountpoint/src";
 	const char RELSRC[] = "src";
 	uint64_t ino = 42;
 
 	expect_getattr(1, S_IFDIR | 01777, UINT64_MAX, 1, 0);
 	expect_lookup(RELSRC, ino, S_IFREG | 0644, UINT64_MAX);
 
 	ASSERT_EQ(-1, rename(FULLSRC, FULLDST));
 	ASSERT_EQ(EPERM, errno);
 }
 
 TEST_F(Rename, eperm_on_sticky_dstdir)
 {
 	const char FULLDST[] = "mountpoint/d/dst";
 	const char RELDSTDIR[] = "d";
 	const char RELDST[] = "dst";
 	const char FULLSRC[] = "mountpoint/src";
 	const char RELSRC[] = "src";
 	uint64_t src_ino = 42;
 	uint64_t dstdir_ino = 43;
 	uint64_t dst_ino = 44;
 
 	expect_getattr(1, S_IFDIR | 0777, UINT64_MAX, 1, 0);
 	expect_lookup(RELSRC, src_ino, S_IFREG | 0644, UINT64_MAX);
 	expect_lookup(RELDSTDIR, dstdir_ino, S_IFDIR | 01777, UINT64_MAX);
 	EXPECT_LOOKUP(dstdir_ino, RELDST)
 	.WillOnce(Invoke(ReturnImmediate([=](auto in __unused, auto out) {
 		SET_OUT_HEADER_LEN(out, entry);
 		out->body.entry.attr.mode = S_IFREG | 0644;
 		out->body.entry.nodeid = dst_ino;
 		out->body.entry.attr_valid = UINT64_MAX;
 		out->body.entry.entry_valid = UINT64_MAX;
 		out->body.entry.attr.uid = 0;
 	})));
 
 	ASSERT_EQ(-1, rename(FULLSRC, FULLDST));
 	ASSERT_EQ(EPERM, errno);
 }
 
 /* Successfully rename a file, overwriting the destination */
 TEST_F(Rename, ok)
 {
 	const char FULLDST[] = "mountpoint/dst";
 	const char RELDST[] = "dst";
 	const char FULLSRC[] = "mountpoint/src";
 	const char RELSRC[] = "src";
 	// The inode of the already-existing destination file
 	uint64_t dst_ino = 2;
 	uint64_t ino = 42;
 
 	expect_getattr(1, S_IFDIR | 0777, UINT64_MAX, 1, geteuid());
 	expect_lookup(RELSRC, ino, S_IFREG | 0644, UINT64_MAX);
 	expect_lookup(RELDST, dst_ino, S_IFREG | 0644, UINT64_MAX);
 	expect_rename(0);
 
 	ASSERT_EQ(0, rename(FULLSRC, FULLDST)) << strerror(errno);
 }
 
 TEST_F(Rename, ok_to_remove_src_because_of_stickiness)
 {
 	const char FULLDST[] = "mountpoint/dst";
 	const char RELDST[] = "dst";
 	const char FULLSRC[] = "mountpoint/src";
 	const char RELSRC[] = "src";
 	uint64_t ino = 42;
 
 	expect_getattr(1, S_IFDIR | 01777, UINT64_MAX, 1, 0);
 	expect_lookup(RELSRC, ino, S_IFREG | 0644, UINT64_MAX, geteuid());
 	EXPECT_LOOKUP(1, RELDST).WillOnce(Invoke(ReturnErrno(ENOENT)));
 	expect_rename(0);
 
 	ASSERT_EQ(0, rename(FULLSRC, FULLDST)) << strerror(errno);
 }
 
 TEST_F(Setattr, ok)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	const uint64_t ino = 42;
 	const mode_t oldmode = 0755;
 	const mode_t newmode = 0644;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | oldmode, UINT64_MAX, geteuid());
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([](auto in) {
 			return (in->header.opcode == FUSE_SETATTR &&
 				in->header.nodeid == ino &&
 				in->body.setattr.mode == newmode);
 		}, Eq(true)),
 		_)
 	).WillOnce(Invoke(ReturnImmediate([](auto in __unused, auto out) {
 		SET_OUT_HEADER_LEN(out, attr);
 		out->body.attr.attr.mode = S_IFREG | newmode;
 	})));
 
 	EXPECT_EQ(0, chmod(FULLPATH, newmode)) << strerror(errno);
 }
 
 TEST_F(Setattr, eacces)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	const uint64_t ino = 42;
 	const mode_t oldmode = 0755;
 	const mode_t newmode = 0644;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | oldmode, UINT64_MAX, 0);
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([](auto in) {
 			return (in->header.opcode == FUSE_SETATTR);
 		}, Eq(true)),
 		_)
 	).Times(0);
 
 	EXPECT_NE(0, chmod(FULLPATH, newmode));
 	EXPECT_EQ(EPERM, errno);
 }
 
 /*
  * ftruncate() of a file without writable permissions should succeed as long as
  * the file descriptor is writable.  This is important when combined with
  * O_CREAT
  */
 TEST_F(Setattr, ftruncate_of_newly_created_file)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	const uint64_t ino = 42;
 	const mode_t mode = 0000;
 	int fd;
 
 	expect_getattr(1, S_IFDIR | 0777, UINT64_MAX, 1);
 	EXPECT_LOOKUP(1, RELPATH).WillOnce(Invoke(ReturnErrno(ENOENT)));
 	expect_create(RELPATH, ino);
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([](auto in) {
 			return (in->header.opcode == FUSE_SETATTR &&
 				in->header.nodeid == ino &&
 				(in->body.setattr.valid & FATTR_SIZE));
 		}, Eq(true)),
 		_)
 	).WillOnce(Invoke(ReturnImmediate([=](auto in __unused, auto out) {
 		SET_OUT_HEADER_LEN(out, attr);
 		out->body.attr.attr.ino = ino;
 		out->body.attr.attr.mode = S_IFREG | mode;
 		out->body.attr.attr_valid = UINT64_MAX;
 	})));
 
 	fd = open(FULLPATH, O_CREAT | O_RDWR, 0);
 	ASSERT_LE(0, fd) << strerror(errno);
 	ASSERT_EQ(0, ftruncate(fd, 100)) << strerror(errno);
 	/* Deliberately leak fd */
 }
 
 /* 
  * Setting the sgid bit should fail for an unprivileged user who doesn't belong
  * to the file's group
  */
 TEST_F(Setattr, sgid_by_non_group_member)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	const uint64_t ino = 42;
 	const mode_t oldmode = 0755;
 	const mode_t newmode = 02755;
 	uid_t uid = geteuid();
 	gid_t gid = excluded_group();
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | oldmode, UINT64_MAX, uid, gid);
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([](auto in) {
 			return (in->header.opcode == FUSE_SETATTR);
 		}, Eq(true)),
 		_)
 	).Times(0);
 
 	EXPECT_NE(0, chmod(FULLPATH, newmode));
 	EXPECT_EQ(EPERM, errno);
 }
 
 /* Only the superuser may set the sticky bit on a non-directory */
 TEST_F(Setattr, sticky_regular_file)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	const uint64_t ino = 42;
 	const mode_t oldmode = 0644;
 	const mode_t newmode = 01644;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | oldmode, UINT64_MAX, geteuid());
 	EXPECT_CALL(*m_mock, process(
 		ResultOf([](auto in) {
 			return (in->header.opcode == FUSE_SETATTR);
 		}, Eq(true)),
 		_)
 	).Times(0);
 
 	EXPECT_NE(0, chmod(FULLPATH, newmode));
 	EXPECT_EQ(EFTYPE, errno);
 }
 
 TEST_F(Setextattr, ok)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	const char value[] = "whatever";
 	ssize_t value_len = strlen(value) + 1;
 	int ns = EXTATTR_NAMESPACE_USER;
 	ssize_t r;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0644, UINT64_MAX, geteuid());
 	expect_setxattr(0);
 
 	r = extattr_set_file(FULLPATH, ns, "foo", (void*)value, value_len);
 	ASSERT_EQ(value_len, r) << strerror(errno);
 }
 
 TEST_F(Setextattr, eacces)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	const char value[] = "whatever";
 	ssize_t value_len = strlen(value) + 1;
 	int ns = EXTATTR_NAMESPACE_USER;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0644, UINT64_MAX, 0);
 
 	ASSERT_EQ(-1,
 		extattr_set_file(FULLPATH, ns, "foo", (void*)value, value_len));
 	ASSERT_EQ(EACCES, errno);
 }
 
 // Setting system attributes requires superuser privileges
 TEST_F(Setextattr, system)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	const char value[] = "whatever";
 	ssize_t value_len = strlen(value) + 1;
 	int ns = EXTATTR_NAMESPACE_SYSTEM;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0666, UINT64_MAX, geteuid());
 
 	ASSERT_EQ(-1,
 		extattr_set_file(FULLPATH, ns, "foo", (void*)value, value_len));
 	ASSERT_EQ(EPERM, errno);
 }
 
 // Setting user attributes merely requires write privileges
 TEST_F(Setextattr, user)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 	const char value[] = "whatever";
 	ssize_t value_len = strlen(value) + 1;
 	int ns = EXTATTR_NAMESPACE_USER;
 	ssize_t r;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0666, UINT64_MAX, 0);
 	expect_setxattr(0);
 
 	r = extattr_set_file(FULLPATH, ns, "foo", (void*)value, value_len);
 	ASSERT_EQ(value_len, r) << strerror(errno);
 }
 
 TEST_F(Unlink, ok)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 
 	expect_getattr(1, S_IFDIR | 0777, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0644, UINT64_MAX, geteuid());
 	expect_unlink(1, RELPATH, 0);
 
 	ASSERT_EQ(0, unlink(FULLPATH)) << strerror(errno);
 }
 
 /*
  * Ensure that a cached name doesn't cause unlink to bypass permission checks
  * in VOP_LOOKUP.
  *
  * This test should pass because lookup(9) purges the namecache entry by doing
  * a vfs_cache_lookup with ~MAKEENTRY when nameiop == DELETE.
  */
 TEST_F(Unlink, cached_unwritable_directory)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	EXPECT_LOOKUP(1, RELPATH)
 	.Times(AnyNumber())
 	.WillRepeatedly(Invoke(
 		ReturnImmediate([=](auto i __unused, auto out) {
 			SET_OUT_HEADER_LEN(out, entry);
 			out->body.entry.attr.mode = S_IFREG | 0644;
 			out->body.entry.nodeid = ino;
 			out->body.entry.entry_valid = UINT64_MAX;
 		}))
 	);
 
 	/* Fill name cache */
 	ASSERT_EQ(0, access(FULLPATH, F_OK)) << strerror(errno);
 	/* Despite cached name , unlink should fail */
 	ASSERT_EQ(-1, unlink(FULLPATH));
 	ASSERT_EQ(EACCES, errno);
 }
 
 TEST_F(Unlink, unwritable_directory)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0644, UINT64_MAX, geteuid());
 
 	ASSERT_EQ(-1, unlink(FULLPATH));
 	ASSERT_EQ(EACCES, errno);
 }
 
 TEST_F(Unlink, sticky_directory)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	uint64_t ino = 42;
 
 	expect_getattr(1, S_IFDIR | 01777, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | 0644, UINT64_MAX, 0);
 
 	ASSERT_EQ(-1, unlink(FULLPATH));
 	ASSERT_EQ(EPERM, errno);
 }
 
 /* A write by a non-owner should clear a file's SUID bit */
 TEST_F(Write, clear_suid)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	struct stat sb;
 	uint64_t ino = 42;
 	mode_t oldmode = 04777;
 	mode_t newmode = 0777;
 	char wbuf[1] = {'x'};
 	int fd;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | oldmode, UINT64_MAX);
 	expect_open(ino, 0, 1);
 	expect_write(ino, 0, sizeof(wbuf), sizeof(wbuf), 0, wbuf);
 	expect_chmod(ino, newmode);
 
 	fd = open(FULLPATH, O_WRONLY);
 	ASSERT_LE(0, fd) << strerror(errno);
 	ASSERT_EQ(1, write(fd, wbuf, sizeof(wbuf))) << strerror(errno);
 	ASSERT_EQ(0, fstat(fd, &sb)) << strerror(errno);
 	EXPECT_EQ(S_IFREG | newmode, sb.st_mode);
 	/* Deliberately leak fd.  close(2) will be tested in release.cc */
 }
 
 /* A write by a non-owner should clear a file's SGID bit */
 TEST_F(Write, clear_sgid)
 {
 	const char FULLPATH[] = "mountpoint/some_file.txt";
 	const char RELPATH[] = "some_file.txt";
 	struct stat sb;
 	uint64_t ino = 42;
 	mode_t oldmode = 02777;
 	mode_t newmode = 0777;
 	char wbuf[1] = {'x'};
 	int fd;
 
 	expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1);
 	expect_lookup(RELPATH, ino, S_IFREG | oldmode, UINT64_MAX);
 	expect_open(ino, 0, 1);
 	expect_write(ino, 0, sizeof(wbuf), sizeof(wbuf), 0, wbuf);
 	expect_chmod(ino, newmode);
 
 	fd = open(FULLPATH, O_WRONLY);
 	ASSERT_LE(0, fd) << strerror(errno);
 	ASSERT_EQ(1, write(fd, wbuf, sizeof(wbuf))) << strerror(errno);
 	ASSERT_EQ(0, fstat(fd, &sb)) << strerror(errno);
 	EXPECT_EQ(S_IFREG | newmode, sb.st_mode);
 	/* Deliberately leak fd.  close(2) will be tested in release.cc */
 }