[$] SMB/CIFS compounding support

In a filesystem-track session at the 2018 Linux Storage, Filesystem, andMemory-Management Summit (LSFMM), Ronnie Sahlberg talked about some changeshe has made to add support for compounding to the SMB/CIFSimplementation in Linux. Compounding is a way to combine multipleoperations into a single request that can help reduce network round-trips.