NFSv4.1 server support for pNFS block layouts

configname: CONFIG_NFSD_BLOCKLAYOUT

Linux Kernel Configuration
└─>File systems
└─>Network File Systems
└─>NFSv4.1 server support for pNFS block layouts
In linux kernel since version 4.1 (release Date: 2015-06-21)  
This option enables support for the exporting pNFS block layouts
in the kernel's NFS server. The pNFS block layout enables NFS
clients to directly perform I/O to block devices accesible to both
the server and the clients. See RFC 5663 for more details.

If unsure, say N.