diff --git a/sys/ufs/ffs/ffs_alloc.c b/sys/ufs/ffs/ffs_alloc.c
index 7ad39e63bb1c..be93dd16cd0a 100644
--- a/sys/ufs/ffs/ffs_alloc.c
+++ b/sys/ufs/ffs/ffs_alloc.c
@@ -3468,7 +3468,7 @@ sysctl_ffs_fsck(SYSCTL_HANDLER_ARGS)
 			break;
 		}
 		dp = VTOI(dvp);
-		dp->i_offset = 12;	/* XXX mastertemplate.dot_reclen */
+		SET_I_OFFSET(dp, 12);	/* XXX mastertemplate.dot_reclen */
 		error = ufs_dirrewrite(dp, VTOI(fdvp), (ino_t)cmd.size,
 		    DT_DIR, 0);
 		cache_purge(fdvp);
diff --git a/sys/ufs/ffs/ffs_softdep.c b/sys/ufs/ffs/ffs_softdep.c
index 6b9c6c30629f..3afd0323ccda 100644
--- a/sys/ufs/ffs/ffs_softdep.c
+++ b/sys/ufs/ffs/ffs_softdep.c
@@ -8764,11 +8764,11 @@ softdep_change_directoryentry_offset(bp, dp, base, oldloc, newloc, entrysize)
 	if (MOUNTEDSUJ(mp)) {
 		flags = DEPALLOC;
 		jmvref = newjmvref(dp, de->d_ino,
-		    dp->i_offset + (oldloc - base),
-		    dp->i_offset + (newloc - base));
+		    I_OFFSET(dp) + (oldloc - base),
+		    I_OFFSET(dp) + (newloc - base));
 	}
-	lbn = lblkno(ump->um_fs, dp->i_offset);
-	offset = blkoff(ump->um_fs, dp->i_offset);
+	lbn = lblkno(ump->um_fs, I_OFFSET(dp));
+	offset = blkoff(ump->um_fs, I_OFFSET(dp));
 	oldoffset = offset + (oldloc - base);
 	newoffset = offset + (newloc - base);
 	ACQUIRE_LOCK(ump);
@@ -9280,7 +9280,7 @@ newdirrem(bp, dp, ip, isrmdir, prevdirremp)
 	jremref = dotremref = dotdotremref = NULL;
 	if (DOINGSUJ(dvp)) {
 		if (isrmdir) {
-			jremref = newjremref(dirrem, dp, ip, dp->i_offset,
+			jremref = newjremref(dirrem, dp, ip, I_OFFSET(dp),
 			    ip->i_effnlink + 2);
 			dotremref = newjremref(dirrem, ip, ip, DOT_OFFSET,
 			    ip->i_effnlink + 1);
@@ -9288,12 +9288,12 @@ newdirrem(bp, dp, ip, isrmdir, prevdirremp)
 			    dp->i_effnlink + 1);
 			dotdotremref->jr_state |= MKDIR_PARENT;
 		} else
-			jremref = newjremref(dirrem, dp, ip, dp->i_offset,
+			jremref = newjremref(dirrem, dp, ip, I_OFFSET(dp),
 			    ip->i_effnlink + 1);
 	}
 	ACQUIRE_LOCK(ump);
-	lbn = lblkno(ump->um_fs, dp->i_offset);
-	offset = blkoff(ump->um_fs, dp->i_offset);
+	lbn = lblkno(ump->um_fs, I_OFFSET(dp));
+	offset = blkoff(ump->um_fs, I_OFFSET(dp));
 	pagedep_lookup(UFSTOVFS(ump), bp, dp->i_number, lbn, DEPALLOC,
 	    &pagedep);
 	dirrem->dm_pagedep = pagedep;
@@ -9304,7 +9304,7 @@ newdirrem(bp, dp, ip, isrmdir, prevdirremp)
 	 * the jremref is preserved for any potential diradd in this
 	 * location.  This can not coincide with a rmdir.
 	 */
-	if (dp->i_offset == DOTDOT_OFFSET) {
+	if (I_OFFSET(dp) == DOTDOT_OFFSET) {
 		if (isrmdir)
 			panic("newdirrem: .. directory change during remove?");
 		jremref = cancel_mkdir_dotdot(dp, dirrem, jremref);
@@ -9405,7 +9405,7 @@ softdep_setup_directory_change(bp, dp, ip, newinum, isrmdir)
 
 	mp = ITOVFS(dp);
 	ump = VFSTOUFS(mp);
-	offset = blkoff(ump->um_fs, dp->i_offset);
+	offset = blkoff(ump->um_fs, I_OFFSET(dp));
 	KASSERT(MOUNTEDSOFTDEP(mp) != 0,
 	   ("softdep_setup_directory_change called on non-softdep filesystem"));
 
@@ -9508,7 +9508,7 @@ softdep_setup_directory_change(bp, dp, ip, newinum, isrmdir)
 		KASSERT(jaddref != NULL && jaddref->ja_parent == dp->i_number,
 		    ("softdep_setup_directory_change: bad jaddref %p",
 		    jaddref));
-		jaddref->ja_diroff = dp->i_offset;
+		jaddref->ja_diroff = I_OFFSET(dp);
 		jaddref->ja_diradd = dap;
 		LIST_INSERT_HEAD(&pagedep->pd_diraddhd[DIRADDHASH(offset)],
 		    dap, da_pdlist);
@@ -9527,7 +9527,7 @@ softdep_setup_directory_change(bp, dp, ip, newinum, isrmdir)
 	 * committed when need to move the dot and dotdot references to
 	 * this new name.
 	 */
-	if (inodedep->id_mkdiradd && dp->i_offset != DOTDOT_OFFSET)
+	if (inodedep->id_mkdiradd && I_OFFSET(dp) != DOTDOT_OFFSET)
 		merge_diradd(inodedep, dap);
 	FREE_LOCK(ump);
 }
diff --git a/sys/ufs/ffs/ffs_vfsops.c b/sys/ufs/ffs/ffs_vfsops.c
index ac61a9617651..0e275c1c5551 100644
--- a/sys/ufs/ffs/ffs_vfsops.c
+++ b/sys/ufs/ffs/ffs_vfsops.c
@@ -2001,6 +2001,9 @@ ffs_vgetf(mp, ino, flags, vpp, ffs_flags)
 	ip->i_nextclustercg = -1;
 	ip->i_flag = fs->fs_magic == FS_UFS1_MAGIC ? 0 : IN_UFS2;
 	ip->i_mode = 0; /* ensure error cases below throw away vnode */
+#ifdef DIAGNOSTIC
+	ufs_init_trackers(ip);
+#endif
 #ifdef QUOTA
 	{
 		int i;
diff --git a/sys/ufs/ffs/ffs_vnops.c b/sys/ufs/ffs/ffs_vnops.c
index b86266aebde0..bb7a6858c863 100644
--- a/sys/ufs/ffs/ffs_vnops.c
+++ b/sys/ufs/ffs/ffs_vnops.c
@@ -434,16 +434,20 @@ ffs_lock(ap)
 	struct vop_lock1_args /* {
 		struct vnode *a_vp;
 		int a_flags;
-		struct thread *a_td;
 		char *file;
 		int line;
 	} */ *ap;
 {
+#if !defined(NO_FFS_SNAPSHOT) || defined(DIAGNOSTIC)
+	struct vnode *vp = ap->a_vp;
+#endif	/* !NO_FFS_SNAPSHOT || DIAGNOSTIC */
+#ifdef DIAGNOSTIC
+	struct inode *ip;
+#endif	/* DIAGNOSTIC */
+	int result;
 #ifndef NO_FFS_SNAPSHOT
-	struct vnode *vp;
 	int flags;
 	struct lock *lkp;
-	int result;
 
 	/*
 	 * Adaptive spinning mixed with SU leads to trouble. use a giant hammer
@@ -456,12 +460,11 @@ ffs_lock(ap)
 	case LK_SHARED:
 	case LK_UPGRADE:
 	case LK_EXCLUSIVE:
-		vp = ap->a_vp;
 		flags = ap->a_flags;
 		for (;;) {
 #ifdef DEBUG_VFS_LOCKS
 			VNPASS(vp->v_holdcnt != 0, vp);
-#endif
+#endif	/* DEBUG_VFS_LOCKS */
 			lkp = vp->v_vnlock;
 			result = lockmgr_lock_flags(lkp, flags,
 			    &VI_MTX(vp)->lock_object, ap->a_file, ap->a_line);
@@ -483,28 +486,67 @@ ffs_lock(ap)
 				flags = (flags & ~LK_TYPE_MASK) | LK_EXCLUSIVE;
 			flags &= ~LK_INTERLOCK;
 		}
+#ifdef DIAGNOSTIC
+		switch (ap->a_flags & LK_TYPE_MASK) {
+		case LK_UPGRADE:
+		case LK_EXCLUSIVE:
+			if (result == 0 && vp->v_vnlock->lk_recurse == 0) {
+				ip = VTOI(vp);
+				if (ip != NULL)
+					ip->i_lock_gen++;
+			}
+		}
+#endif	/* DIAGNOSTIC */
 		break;
 	default:
+#ifdef DIAGNOSTIC
+		if ((ap->a_flags & LK_TYPE_MASK) == LK_DOWNGRADE) {
+			ip = VTOI(vp);
+			if (ip != NULL)
+				ufs_unlock_tracker(ip);
+		}
+#endif	/* DIAGNOSTIC */
 		result = VOP_LOCK1_APV(&ufs_vnodeops, ap);
+		break;
 	}
-	return (result);
-#else
+#else	/* NO_FFS_SNAPSHOT */
 	/*
 	 * See above for an explanation.
 	 */
 	if ((ap->a_flags & LK_NODDLKTREAT) != 0)
 		ap->a_flags |= LK_ADAPTIVE;
-	return (VOP_LOCK1_APV(&ufs_vnodeops, ap));
-#endif
+#ifdef DIAGNOSTIC
+	if ((ap->a_flags & LK_TYPE_MASK) == LK_DOWNGRADE) {
+		ip = VTOI(vp);
+		if (ip != NULL)
+			ufs_unlock_tracker(ip);
+	}
+#endif	/* DIAGNOSTIC */
+	result =  VOP_LOCK1_APV(&ufs_vnodeops, ap);
+#endif	/* NO_FFS_SNAPSHOT */
+#ifdef DIAGNOSTIC
+	switch (ap->a_flags & LK_TYPE_MASK) {
+	case LK_UPGRADE:
+	case LK_EXCLUSIVE:
+		if (result == 0 && vp->v_vnlock->lk_recurse == 0) {
+			ip = VTOI(vp);
+			if (ip != NULL)
+				ip->i_lock_gen++;
+		}
+	}
+#endif	/* DIAGNOSTIC */
+	return (result);
 }
 
 #ifdef INVARIANTS
 static int
 ffs_unlock_debug(struct vop_unlock_args *ap)
 {
-	struct vnode *vp = ap->a_vp;
-	struct inode *ip = VTOI(vp);
+	struct vnode *vp;
+	struct inode *ip;
 
+	vp = ap->a_vp;
+	ip = VTOI(vp);
 	if (ip->i_flag & UFS_INODE_FLAG_LAZY_MASK_ASSERTABLE) {
 		if ((vp->v_mflag & VMP_LAZYLIST) == 0) {
 			VI_LOCK(vp);
@@ -514,6 +556,11 @@ ffs_unlock_debug(struct vop_unlock_args *ap)
 			VI_UNLOCK(vp);
 		}
 	}
+#ifdef DIAGNOSTIC
+	if (VOP_ISLOCKED(vp) == LK_EXCLUSIVE && ip != NULL &&
+	    vp->v_vnlock->lk_recurse == 0)
+		ufs_unlock_tracker(ip);
+#endif
 	return (VOP_UNLOCK_APV(&ufs_vnodeops, ap));
 }
 #endif
diff --git a/sys/ufs/ufs/inode.h b/sys/ufs/ufs/inode.h
index 70f7ab5facf7..16db8d6d5cea 100644
--- a/sys/ufs/ufs/inode.h
+++ b/sys/ufs/ufs/inode.h
@@ -44,12 +44,24 @@
 #include <sys/queue.h>
 #include <ufs/ufs/dinode.h>
 #include <sys/seqc.h>
+#ifdef DIAGNOSTIC
+#include <sys/stack.h>
+#endif
 
 /*
  * This must agree with the definition in <ufs/ufs/dir.h>.
  */
 #define	doff_t		int32_t
 
+#ifdef DIAGNOSTIC
+struct iown_tracker {
+	struct thread	*tr_owner;
+	struct stack	tr_st;
+	struct stack	tr_unlock;
+	int		tr_gen;
+};
+#endif
+
 /*
  * The inode is used to describe each active (or recently active) file in the
  * UFS filesystem. It is composed of two types of information. The first part
@@ -94,6 +106,12 @@ struct inode {
 	doff_t	  i_endoff;	/* End of useful stuff in directory. */
 	doff_t	  i_diroff;	/* Offset in dir, where we found last entry. */
 	doff_t	  i_offset;	/* Offset of free space in directory. */
+#ifdef DIAGNOSTIC
+	int			i_lock_gen;
+	struct iown_tracker	i_count_tracker;
+	struct iown_tracker	i_endoff_tracker;
+	struct iown_tracker	i_offset_tracker;
+#endif
 
 	int	i_nextclustercg; /* last cg searched for cluster */
 
@@ -254,6 +272,35 @@ struct ufid {
 	uint32_t  ufid_ino;	/* File number (ino). */
 	uint32_t  ufid_gen;	/* Generation number. */
 };
+
+#ifdef DIAGNOSTIC
+void ufs_init_trackers(struct inode *ip);
+void ufs_unlock_tracker(struct inode *ip);
+
+doff_t ufs_get_i_offset(struct inode *ip, const char *file, int line);
+void ufs_set_i_offset(struct inode *ip, doff_t off, const char *file, int line);
+#define	I_OFFSET(ip)		ufs_get_i_offset(ip, __FILE__, __LINE__)
+#define	SET_I_OFFSET(ip, off)	ufs_set_i_offset(ip, off, __FILE__, __LINE__)
+
+int32_t ufs_get_i_count(struct inode *ip, const char *file, int line);
+void ufs_set_i_count(struct inode *ip, int32_t cnt, const char *file, int line);
+#define	I_COUNT(ip)		ufs_get_i_count(ip, __FILE__, __LINE__)
+#define	SET_I_COUNT(ip, cnt)	ufs_set_i_count(ip, cnt, __FILE__, __LINE__)
+
+doff_t ufs_get_i_endoff(struct inode *ip, const char *file, int line);
+void ufs_set_i_endoff(struct inode *ip, doff_t off, const char *file, int line);
+#define	I_ENDOFF(ip)		ufs_get_i_endoff(ip, __FILE__, __LINE__)
+#define	SET_I_ENDOFF(ip, off)	ufs_set_i_endoff(ip, off, __FILE__, __LINE__)
+
+#else
+#define	I_OFFSET(ip)		((ip)->i_offset)
+#define	SET_I_OFFSET(ip, off)	((ip)->i_offset = (off))
+#define	I_COUNT(ip)		((ip)->i_count)
+#define	SET_I_COUNT(ip, cnt)	((ip)->i_count = cnt)
+#define	I_ENDOFF(ip)		((ip)->i_endoff)
+#define	SET_I_ENDOFF(ip, off)	((ip)->i_endoff = off)
+#endif
+
 #endif /* _KERNEL */
 
 #endif /* !_UFS_UFS_INODE_H_ */
diff --git a/sys/ufs/ufs/ufs_lookup.c b/sys/ufs/ufs/ufs_lookup.c
index ca151037a960..9566e436165c 100644
--- a/sys/ufs/ufs/ufs_lookup.c
+++ b/sys/ufs/ufs/ufs_lookup.c
@@ -66,6 +66,7 @@ __FBSDID("$FreeBSD$");
 #endif
 #include <ufs/ufs/ufsmount.h>
 #include <ufs/ufs/ufs_extern.h>
+#include <ufs/ffs/ffs_extern.h>
 
 #ifdef DIAGNOSTIC
 static int	dirchk = 1;
@@ -504,22 +505,22 @@ ufs_lookup_ino(struct vnode *vdp, struct vnode **vpp, struct componentname *cnp,
 		 * dp->i_offset + dp->i_count.
 		 */
 		if (slotstatus == NONE) {
-			dp->i_offset = roundup2(dp->i_size, DIRBLKSIZ);
-			dp->i_count = 0;
-			enduseful = dp->i_offset;
+			SET_I_OFFSET(dp, roundup2(dp->i_size, DIRBLKSIZ));
+			SET_I_COUNT(dp, 0);
+			enduseful = I_OFFSET(dp);
 		} else if (nameiop == DELETE) {
-			dp->i_offset = slotoffset;
-			if ((dp->i_offset & (DIRBLKSIZ - 1)) == 0)
-				dp->i_count = 0;
+			SET_I_OFFSET(dp, slotoffset);
+			if ((I_OFFSET(dp) & (DIRBLKSIZ - 1)) == 0)
+				SET_I_COUNT(dp, 0);
 			else
-				dp->i_count = dp->i_offset - prevoff;
+				SET_I_COUNT(dp, I_OFFSET(dp) - prevoff);
 		} else {
-			dp->i_offset = slotoffset;
-			dp->i_count = slotsize;
+			SET_I_OFFSET(dp, slotoffset);
+			SET_I_COUNT(dp, slotsize);
 			if (enduseful < slotoffset + slotsize)
 				enduseful = slotoffset + slotsize;
 		}
-		dp->i_endoff = roundup2(enduseful, DIRBLKSIZ);
+		SET_I_ENDOFF(dp, roundup2(enduseful, DIRBLKSIZ));
 		/*
 		 * We return with the directory locked, so that
 		 * the parameters we set up above will still be
@@ -575,24 +576,32 @@ ufs_lookup_ino(struct vnode *vdp, struct vnode **vpp, struct componentname *cnp,
 	if (nameiop == DELETE && (flags & ISLASTCN)) {
 		if (flags & LOCKPARENT)
 			ASSERT_VOP_ELOCKED(vdp, __FUNCTION__);
-		/*
-		 * Return pointer to current entry in dp->i_offset,
-		 * and distance past previous entry (if there
-		 * is a previous entry in this block) in dp->i_count.
-		 * Save directory inode pointer in ndp->ni_dvp for dirremove().
-		 *
-		 * Technically we shouldn't be setting these in the
-		 * WANTPARENT case (first lookup in rename()), but any
-		 * lookups that will result in directory changes will
-		 * overwrite these.
-		 */
-		dp->i_offset = i_offset;
-		if ((dp->i_offset & (DIRBLKSIZ - 1)) == 0)
-			dp->i_count = 0;
-		else
-			dp->i_count = dp->i_offset - prevoff;
+
+		if (VOP_ISLOCKED(vdp) == LK_EXCLUSIVE) {
+			/*
+			 * Return pointer to current entry in
+			 * dp->i_offset, and distance past previous
+			 * entry (if there is a previous entry in this
+			 * block) in dp->i_count.
+			 *
+			 * We shouldn't be setting these in the
+			 * WANTPARENT case (first lookup in rename()), but any
+			 * lookups that will result in directory changes will
+			 * overwrite these.
+			 */
+			SET_I_OFFSET(dp, i_offset);
+			if ((I_OFFSET(dp) & (DIRBLKSIZ - 1)) == 0)
+				SET_I_COUNT(dp, 0);
+			else
+				SET_I_COUNT(dp, I_OFFSET(dp) - prevoff);
+		}
 		if (dd_ino != NULL)
 			return (0);
+
+		/*
+		 * Save directory inode pointer in ndp->ni_dvp for
+		 * dirremove().
+		 */
 		if ((error = VFS_VGET(vdp->v_mount, ino,
 		    LK_EXCLUSIVE, &tdp)) != 0)
 			return (error);
@@ -629,7 +638,7 @@ ufs_lookup_ino(struct vnode *vdp, struct vnode **vpp, struct componentname *cnp,
 		 * Careful about locking second inode.
 		 * This can only occur if the target is ".".
 		 */
-		dp->i_offset = i_offset;
+		SET_I_OFFSET(dp, i_offset);
 		if (dp->i_number == ino)
 			return (EISDIR);
 		if (dd_ino != NULL)
@@ -887,14 +896,14 @@ ufs_direnter(dvp, tvp, dirp, cnp, newdirbp, isrename)
 	dp = VTOI(dvp);
 	newentrysize = DIRSIZ(OFSFMT(dvp), dirp);
 
-	if (dp->i_count == 0) {
+	if (I_COUNT(dp) == 0) {
 		/*
 		 * If dp->i_count is 0, then namei could find no
 		 * space in the directory. Here, dp->i_offset will
 		 * be on a directory block boundary and we will write the
 		 * new entry into a fresh block.
 		 */
-		if (dp->i_offset & (DIRBLKSIZ - 1))
+		if (I_OFFSET(dp) & (DIRBLKSIZ - 1))
 			panic("ufs_direnter: newblk");
 		flags = BA_CLRBUF;
 		if (!DOINGSOFTDEP(dvp) && !DOINGASYNC(dvp))
@@ -907,28 +916,28 @@ ufs_direnter(dvp, tvp, dirp, cnp, newdirbp, isrename)
 		}
 #endif
 		old_isize = dp->i_size;
-		vnode_pager_setsize(dvp, (u_long)dp->i_offset + DIRBLKSIZ);
-		if ((error = UFS_BALLOC(dvp, (off_t)dp->i_offset, DIRBLKSIZ,
+		vnode_pager_setsize(dvp, (u_long)I_OFFSET(dp) + DIRBLKSIZ);
+		if ((error = UFS_BALLOC(dvp, (off_t)I_OFFSET(dp), DIRBLKSIZ,
 		    cr, flags, &bp)) != 0) {
 			if (DOINGSOFTDEP(dvp) && newdirbp != NULL)
 				bdwrite(newdirbp);
 			vnode_pager_setsize(dvp, (u_long)old_isize);
 			return (error);
 		}
-		dp->i_size = dp->i_offset + DIRBLKSIZ;
+		dp->i_size = I_OFFSET(dp) + DIRBLKSIZ;
 		DIP_SET(dp, i_size, dp->i_size);
-		dp->i_endoff = dp->i_size;
+		SET_I_ENDOFF(dp, dp->i_size);
 		UFS_INODE_SET_FLAG(dp, IN_SIZEMOD | IN_CHANGE | IN_UPDATE);
 		dirp->d_reclen = DIRBLKSIZ;
-		blkoff = dp->i_offset &
+		blkoff = I_OFFSET(dp) &
 		    (VFSTOUFS(dvp->v_mount)->um_mountp->mnt_stat.f_iosize - 1);
 		bcopy((caddr_t)dirp, (caddr_t)bp->b_data + blkoff,newentrysize);
 #ifdef UFS_DIRHASH
 		if (dp->i_dirhash != NULL) {
-			ufsdirhash_newblk(dp, dp->i_offset);
-			ufsdirhash_add(dp, dirp, dp->i_offset);
+			ufsdirhash_newblk(dp, I_OFFSET(dp));
+			ufsdirhash_add(dp, dirp, I_OFFSET(dp));
 			ufsdirhash_checkblock(dp, (char *)bp->b_data + blkoff,
-			    dp->i_offset);
+			    I_OFFSET(dp));
 		}
 #endif
 		if (DOINGSOFTDEP(dvp)) {
@@ -944,7 +953,7 @@ ufs_direnter(dvp, tvp, dirp, cnp, newdirbp, isrename)
 				   (bp->b_data + blkoff))->d_reclen = DIRBLKSIZ;
 				blkoff += DIRBLKSIZ;
 			}
-			if (softdep_setup_directory_add(bp, dp, dp->i_offset,
+			if (softdep_setup_directory_add(bp, dp, I_OFFSET(dp),
 			    dirp->d_ino, newdirbp, 1))
 				UFS_INODE_SET_FLAG(dp, IN_NEEDSYNC);
 			if (newdirbp)
@@ -1001,15 +1010,15 @@ ufs_direnter(dvp, tvp, dirp, cnp, newdirbp, isrename)
 	 *
 	 * N.B. - THIS IS AN ARTIFACT OF 4.2 AND SHOULD NEVER HAPPEN.
 	 */
-	if (dp->i_offset + dp->i_count > dp->i_size) {
-		dp->i_size = dp->i_offset + dp->i_count;
+	if (I_OFFSET(dp) + I_COUNT(dp) > dp->i_size) {
+		dp->i_size = I_OFFSET(dp) + I_COUNT(dp);
 		DIP_SET(dp, i_size, dp->i_size);
 		UFS_INODE_SET_FLAG(dp, IN_SIZEMOD | IN_MODIFIED);
 	}
 	/*
 	 * Get the block containing the space for the new directory entry.
 	 */
-	error = UFS_BLKATOFF(dvp, (off_t)dp->i_offset, &dirbuf, &bp);
+	error = UFS_BLKATOFF(dvp, (off_t)I_OFFSET(dp), &dirbuf, &bp);
 	if (error) {
 		if (DOINGSOFTDEP(dvp) && newdirbp != NULL)
 			bdwrite(newdirbp);
@@ -1024,7 +1033,7 @@ ufs_direnter(dvp, tvp, dirp, cnp, newdirbp, isrename)
 	ep = (struct direct *)dirbuf;
 	dsize = ep->d_ino ? DIRSIZ(OFSFMT(dvp), ep) : 0;
 	spacefree = ep->d_reclen - dsize;
-	for (loc = ep->d_reclen; loc < dp->i_count; ) {
+	for (loc = ep->d_reclen; loc < I_COUNT(dp); ) {
 		nep = (struct direct *)(dirbuf + loc);
 
 		/* Trim the existing slot (NB: dsize may be zero). */
@@ -1052,8 +1061,8 @@ ufs_direnter(dvp, tvp, dirp, cnp, newdirbp, isrename)
 #ifdef UFS_DIRHASH
 		if (dp->i_dirhash != NULL)
 			ufsdirhash_move(dp, nep,
-			    dp->i_offset + ((char *)nep - dirbuf),
-			    dp->i_offset + ((char *)ep - dirbuf));
+			    I_OFFSET(dp) + ((char *)nep - dirbuf),
+			    I_OFFSET(dp) + ((char *)ep - dirbuf));
 #endif
 		if (DOINGSOFTDEP(dvp))
 			softdep_change_directoryentry_offset(bp, dp, dirbuf,
@@ -1094,19 +1103,19 @@ ufs_direnter(dvp, tvp, dirp, cnp, newdirbp, isrename)
 #ifdef UFS_DIRHASH
 	if (dp->i_dirhash != NULL && (ep->d_ino == 0 ||
 	    dirp->d_reclen == spacefree))
-		ufsdirhash_add(dp, dirp, dp->i_offset + ((char *)ep - dirbuf));
+		ufsdirhash_add(dp, dirp, I_OFFSET(dp) + ((char *)ep - dirbuf));
 #endif
 	bcopy((caddr_t)dirp, (caddr_t)ep, (u_int)newentrysize);
 #ifdef UFS_DIRHASH
 	if (dp->i_dirhash != NULL)
 		ufsdirhash_checkblock(dp, dirbuf -
-		    (dp->i_offset & (DIRBLKSIZ - 1)),
-		    rounddown2(dp->i_offset, DIRBLKSIZ));
+		    (I_OFFSET(dp) & (DIRBLKSIZ - 1)),
+		    rounddown2(I_OFFSET(dp), DIRBLKSIZ));
 #endif
 
 	if (DOINGSOFTDEP(dvp)) {
 		(void) softdep_setup_directory_add(bp, dp,
-		    dp->i_offset + (caddr_t)ep - dirbuf,
+		    I_OFFSET(dp) + (caddr_t)ep - dirbuf,
 		    dirp->d_ino, newdirbp, 0);
 		if (newdirbp != NULL)
 			bdwrite(newdirbp);
@@ -1128,10 +1137,10 @@ ufs_direnter(dvp, tvp, dirp, cnp, newdirbp, isrename)
 	 * lock on the newly entered node.
 	 */
 	if (isrename == 0 && error == 0 &&
-	    dp->i_endoff && dp->i_endoff < dp->i_size) {
+	    I_ENDOFF(dp) != 0 && I_ENDOFF(dp) < dp->i_size) {
 		if (tvp != NULL)
 			VOP_UNLOCK(tvp);
-		error = UFS_TRUNCATE(dvp, (off_t)dp->i_endoff,
+		error = UFS_TRUNCATE(dvp, (off_t)I_ENDOFF(dp),
 		    IO_NORMAL | (DOINGASYNC(dvp) ? 0 : IO_SYNC), cr);
 		if (error != 0)
 			vn_printf(dvp,
@@ -1139,7 +1148,7 @@ ufs_direnter(dvp, tvp, dirp, cnp, newdirbp, isrename)
 			    error);
 #ifdef UFS_DIRHASH
 		if (error == 0 && dp->i_dirhash != NULL)
-			ufsdirhash_dirtrunc(dp, dp->i_endoff);
+			ufsdirhash_dirtrunc(dp, I_ENDOFF(dp));
 #endif
 		error = 0;
 		if (tvp != NULL)
@@ -1190,9 +1199,9 @@ ufs_dirremove(dvp, ip, flags, isrmdir)
 		}
 	}
 	if (flags & DOWHITEOUT)
-		offset = dp->i_offset;
+		offset = I_OFFSET(dp);
 	else
-		offset = dp->i_offset - dp->i_count;
+		offset = I_OFFSET(dp) - I_COUNT(dp);
 	if ((error = UFS_BLKATOFF(dvp, offset, (char **)&ep, &bp)) != 0) {
 		if (ip) {
 			ip->i_effnlink++;
@@ -1216,7 +1225,7 @@ ufs_dirremove(dvp, ip, flags, isrmdir)
 		goto out;
 	}
 	/* Set 'rep' to the entry being removed. */
-	if (dp->i_count == 0)
+	if (I_COUNT(dp) == 0)
 		rep = ep;
 	else
 		rep = (struct direct *)((char *)ep + ep->d_reclen);
@@ -1226,7 +1235,7 @@ ufs_dirremove(dvp, ip, flags, isrmdir)
 	 * that `ep' is the previous entry when dp->i_count != 0.
 	 */
 	if (dp->i_dirhash != NULL)
-		ufsdirhash_remove(dp, rep, dp->i_offset);
+		ufsdirhash_remove(dp, rep, I_OFFSET(dp));
 #endif
 	if (ip && rep->d_ino != ip->i_number)
 		panic("ufs_dirremove: ip %ju does not match dirent ino %ju\n",
@@ -1240,7 +1249,7 @@ ufs_dirremove(dvp, ip, flags, isrmdir)
 	rep->d_type = 0;
 	rep->d_ino = 0;
 
-	if (dp->i_count != 0) {
+	if (I_COUNT(dp) != 0) {
 		/*
 		 * Collapse new free space into previous entry.
 		 */
@@ -1250,8 +1259,8 @@ ufs_dirremove(dvp, ip, flags, isrmdir)
 #ifdef UFS_DIRHASH
 	if (dp->i_dirhash != NULL)
 		ufsdirhash_checkblock(dp, (char *)ep -
-		    ((dp->i_offset - dp->i_count) & (DIRBLKSIZ - 1)),
-		    rounddown2(dp->i_offset, DIRBLKSIZ));
+		    ((I_OFFSET(dp) - I_COUNT(dp)) & (DIRBLKSIZ - 1)),
+		    rounddown2(I_OFFSET(dp), DIRBLKSIZ));
 #endif
 out:
 	error = 0;
@@ -1313,7 +1322,7 @@ ufs_dirrewrite(dp, oip, newinum, newtype, isrmdir)
 		UFS_INODE_SET_FLAG(oip, IN_CHANGE);
 	}
 
-	error = UFS_BLKATOFF(vdp, (off_t)dp->i_offset, (char **)&ep, &bp);
+	error = UFS_BLKATOFF(vdp, (off_t)I_OFFSET(dp), (char **)&ep, &bp);
 	if (error == 0 && ep->d_namlen == 2 && ep->d_name[1] == '.' &&
 	    ep->d_name[0] == '.' && ep->d_ino != oip->i_number) {
 		brelse(bp);
@@ -1522,3 +1531,115 @@ ufs_checkpath(ino_t source_ino, ino_t parent_ino, struct inode *target, struct u
 		vput(vp);
 	return (error);
 }
+
+#ifdef DIAGNOSTIC
+static void
+ufs_assert_inode_offset_owner(struct inode *ip, struct iown_tracker *tr,
+    const char *name, const char *file, int line)
+{
+	char msg[128];
+
+	snprintf(msg, sizeof(msg), "at %s@%d", file, line);
+	ASSERT_VOP_ELOCKED(ITOV(ip), msg);
+	MPASS((ip->i_mode & IFMT) == IFDIR);
+	if (curthread == tr->tr_owner && ip->i_lock_gen == tr->tr_gen)
+		return;
+	printf("locked at\n");
+	stack_print(&tr->tr_st);
+	printf("unlocked at\n");
+	stack_print(&tr->tr_unlock);
+	panic("%s ip %p %jd offset owner %p %d gen %d "
+	    "curthread %p %d gen %d at %s@%d\n",
+	    name, ip, (uintmax_t)ip->i_number, tr->tr_owner,
+	    tr->tr_owner->td_tid, tr->tr_gen,
+	    curthread, curthread->td_tid, ip->i_lock_gen,
+	    file, line);
+}
+
+static void
+ufs_set_inode_offset_owner(struct inode *ip, struct iown_tracker *tr,
+    const char *file, int line)
+{
+	char msg[128];
+
+	snprintf(msg, sizeof(msg), "at %s@%d", file, line);
+	ASSERT_VOP_ELOCKED(ITOV(ip), msg);
+	MPASS((ip->i_mode & IFMT) == IFDIR);
+	tr->tr_owner = curthread;
+	tr->tr_gen = ip->i_lock_gen;
+	stack_save(&tr->tr_st);
+}
+
+static void
+ufs_init_one_tracker(struct iown_tracker *tr)
+{
+	tr->tr_owner = NULL;
+	stack_zero(&tr->tr_st);
+}
+
+void
+ufs_init_trackers(struct inode *ip)
+{
+	ufs_init_one_tracker(&ip->i_offset_tracker);
+	ufs_init_one_tracker(&ip->i_count_tracker);
+	ufs_init_one_tracker(&ip->i_endoff_tracker);
+}
+
+void
+ufs_unlock_tracker(struct inode *ip)
+{
+	if (ip->i_count_tracker.tr_gen == ip->i_lock_gen)
+		stack_save(&ip->i_count_tracker.tr_unlock);
+	if (ip->i_offset_tracker.tr_gen == ip->i_lock_gen)
+		stack_save(&ip->i_offset_tracker.tr_unlock);
+	if (ip->i_endoff_tracker.tr_gen == ip->i_lock_gen)
+		stack_save(&ip->i_endoff_tracker.tr_unlock);
+	ip->i_lock_gen++;
+}
+
+doff_t
+ufs_get_i_offset(struct inode *ip, const char *file, int line)
+{
+	ufs_assert_inode_offset_owner(ip, &ip->i_offset_tracker, "i_offset",
+	    file, line);
+	return (ip->i_offset);
+}
+
+void
+ufs_set_i_offset(struct inode *ip, doff_t off, const char *file, int line)
+{
+	ufs_set_inode_offset_owner(ip, &ip->i_offset_tracker, file, line);
+	ip->i_offset = off;
+}
+
+int32_t
+ufs_get_i_count(struct inode *ip, const char *file, int line)
+{
+	ufs_assert_inode_offset_owner(ip, &ip->i_count_tracker, "i_count",
+	    file, line);
+	return (ip->i_count);
+}
+
+void
+ufs_set_i_count(struct inode *ip, int32_t cnt, const char *file, int line)
+{
+	ufs_set_inode_offset_owner(ip, &ip->i_count_tracker, file, line);
+	ip->i_count = cnt;
+}
+
+doff_t
+ufs_get_i_endoff(struct inode *ip, const char *file, int line)
+{
+	ufs_assert_inode_offset_owner(ip, &ip->i_endoff_tracker, "i_endoff",
+	    file, line);
+	return (ip->i_endoff);
+}
+
+void
+ufs_set_i_endoff(struct inode *ip, doff_t off, const char *file, int line)
+{
+	ufs_set_inode_offset_owner(ip, &ip->i_endoff_tracker, file, line);
+	ip->i_endoff = off;
+}
+
+#endif
diff --git a/sys/ufs/ufs/ufs_vnops.c b/sys/ufs/ufs/ufs_vnops.c
index 3034cbd24077..4d241bd53eea 100644
--- a/sys/ufs/ufs/ufs_vnops.c
+++ b/sys/ufs/ufs/ufs_vnops.c
@@ -1481,9 +1481,9 @@ ufs_rename(ap)
 		if (error)
 			goto bad;
 		/* Setup tdvp for directory compaction if needed. */
-		if (tdp->i_count && tdp->i_endoff &&
-		    tdp->i_endoff < tdp->i_size)
-			endoff = tdp->i_endoff;
+		if (I_COUNT(tdp) != 0 && I_ENDOFF(tdp) != 0 &&
+		    I_ENDOFF(tdp) < tdp->i_size)
+			endoff = I_ENDOFF(tdp);
 	} else {
 		if (ITODEV(tip) != ITODEV(tdp) || ITODEV(tip) != ITODEV(fip))
 			panic("ufs_rename: EXDEV");
@@ -1611,7 +1611,7 @@ ufs_rename(ap)
 		} else if (DOINGSUJ(tdvp))
 			/* Journal must account for each new link. */
 			softdep_setup_dotdot_link(tdp, fip);
-		fip->i_offset = mastertemplate.dot_reclen;
+		SET_I_OFFSET(fip, mastertemplate.dot_reclen);
 		ufs_dirrewrite(fip, fdp, newparent, DT_DIR, 0);
 		cache_purge(fdvp);
 	}