FreeBSD/sys/kern/vfs_bio.c
/*
 *	bbarrierwrite:
 *
 *	Synchronous barrier write.  Start output on a buffer and wait for
 *	it to complete.  Place a write barrier after this write so that
 *	this buffer and all buffers written before it are committed to 
 *	the disk before any buffers written after this write are committed
 *	to the disk.  The buffer is released when the output completes.
 */
Synchronous barrier write.  Start output on a buffer and wait for
it to complete.  Place a write barrier after this write so that
this buffer and all buffers written before it are committed to
the disk before any buffers written after this write are committed
to the disk.  The buffer is released when the output completes.
Synchronous barrier write . Start output on a buffer and wait for it to complete . Place a write barrier after this write so that this buffer and all buffers written before it are committed to the disk before any buffers written after this write are committed to the disk . The buffer is released when the output completes .
int
bbarrierwrite(struct buf *bp)
{
	bp->b_flags |= B_BARRIER;
	return (bwrite(bp));
}
int bbarrierwrite ( struct buf * bp ) { bp -> b_flags |= B_BARRIER ; return ( bwrite ( bp ) ) ; }
bbarrierwrite:
      Synchronous barrier write.
bbarrierwrite : Synchronous barrier write .