FreeBSD/sys/kern/vfs_default.c
/*
 *	vop_nostrategy:
 *
 *	Strategy routine for VFS devices that have none.
 *
 *	BIO_ERROR and B_INVAL must be cleared prior to calling any strategy
 *	routine.  Typically this is done for a BIO_READ strategy call.
 *	Typically B_INVAL is assumed to already be clear prior to a write
 *	and should not be cleared manually unless you just made the buffer
 *	invalid.  BIO_ERROR should be cleared either way.
 */
Strategy routine for VFS devices that have none.

BIO_ERROR and B_INVAL must be cleared prior to calling any strategy
routine.  Typically this is done for a BIO_READ strategy call.
Typically B_INVAL is assumed to already be clear prior to a write
and should not be cleared manually unless you just made the buffer
invalid.  BIO_ERROR should be cleared either way.
Strategy routine for VFS devices that have none . BIO_ERROR and B_INVAL must be cleared prior to calling any strategy routine . Typically this is done for a BIO_READ strategy call . Typically B_INVAL is assumed to already be clear prior to a write and should not be cleared manually unless you just made the buffer invalid . BIO_ERROR should be cleared either way .
static int
vop_nostrategy (struct vop_strategy_args *ap)
{
	printf("No strategy for buffer at %p\n", ap->a_bp);
	vprint("vnode", ap->a_vp);
	ap->a_bp->b_ioflags |= BIO_ERROR;
	ap->a_bp->b_error = EOPNOTSUPP;
	bufdone(ap->a_bp);
	return (EOPNOTSUPP);
}
static int vop_nostrategy ( struct vop_strategy_args * ap ) { printf ( " \n " , ap -> a_bp ) ; vprint ( " " , ap -> a_vp ) ; ap -> a_bp -> b_ioflags |= BIO_ERROR ; ap -> a_bp -> b_error = EOPNOTSUPP ; bufdone ( ap -> a_bp ) ; return ( EOPNOTSUPP ) ; }
vop_nostrategy:
      Strategy routine for VFS devices that have none.
vop_nostrategy : Strategy routine for VFS devices that have none .