Index: sys/kern/vfs_vnops.c
===================================================================
--- sys/kern/vfs_vnops.c
+++ sys/kern/vfs_vnops.c
@@ -3461,11 +3461,18 @@
 	return (error);
 }
 
+#define IO_VOPFCRED (1 << IO_SEQSHIFT)
+
+/*
+ * As this does not accept higher 16-bit in ioflag, the higher part is used
+ * to pass internal flags.
+ */
 static int
 vn_deallocate_impl(struct vnode *vp, off_t *offset, off_t *length, int flags,
     int ioflag, struct ucred *active_cred, struct ucred *file_cred)
 {
 	struct mount *mp;
+	struct ucred *cred;
 	void *rl_cookie;
 	off_t off, len;
 	int error;
@@ -3478,6 +3485,11 @@
 	mp = NULL;
 	off = *offset;
 	len = *length;
+	ioflag &= (1 << IO_SEQSHIFT) - 1;
+	if (file_cred != NOCRED && (ioflag & IO_VOPFCRED) != 0)
+		cred = file_cred;
+	else
+		cred = active_cred;
 
 	if ((ioflag & (IO_NODELOCKED | IO_RANGELOCKED)) == 0)
 		rl_cookie = vn_rangelock_wlock(vp, off, off + len);
@@ -3510,7 +3522,7 @@
 #endif
 		if (error == 0)
 			error = VOP_DEALLOCATE(vp, &off, &len, flags, ioflag,
-			    active_cred);
+			    cred);
 
 		if ((ioflag & IO_NODELOCKED) == 0) {
 			VOP_UNLOCK(vp);
@@ -3530,16 +3542,21 @@
 	return (error);
 }
 
+/*
+ * If file_cred is not NOCRED, it is chosen over active_cred.
+ * Sequential heuristic in ioflag is not accepted.
+ */
 int
 vn_deallocate(struct vnode *vp, off_t *offset, off_t *length, int flags,
     int ioflag, struct ucred *active_cred, struct ucred *file_cred)
 {
 	if (*offset < 0 || *length <= 0 || *length > OFF_MAX - *offset ||
-	    flags != 0)
+	    flags != 0 || (ioflag >> IO_SEQSHIFT) != 0)
 		return (EINVAL);
 	if (vp->v_type != VREG)
 		return (ENODEV);
 
+	ioflag |= IO_VOPFCRED;
 	return (vn_deallocate_impl(vp, offset, length, flags, ioflag,
 	    active_cred, file_cred));
 }