I'm looking for the source code of both NFS client and NFS server, in order to do so change inside the code, but unfortunately I was not able to find the source code.
Can anyone help, to locate their source codes? Are they located inside the linux kernel or they are external modules?
They are in the kernel source tree in directory "fs/nfs"
You can browse the latest code here (link updated 2020/11/13 as old one dead)