/* * Create a writable copy of the mbuf chain. While doing this * we compact the chain with a goal of producing a chain with * at most two mbufs. The second mbuf in this chain is likely * to be a cluster. The primary purpose of this work is to create * a writable packet for encryption, compression, etc. The * secondary goal is to linearize the data so the data can be * passed to crypto hardware in the most efficient manner possible. */