I need to build a custom Suse Linux NFS Server that does compression on certain files that are stored on the disk, and decompresses files as they are read from the disk. This needs to be transparent to the remote users of the file system, meaning that if a user saves a 10MB file named XYZZY.tif on /archiveDirectoryOnNFSServer, that when they do a ls -l on that mounted directory, they will see a 10MB file called XYZZY.tif, even though the actual file stored on the disk on the NFS server will be XYZZY.tif.compressed, and it will be 2MB in size.
I'm expecting that I need to build this as a driver that sits below the NFS Server software stack, but, I'm having difficulty finding where to start. Are there existing NFS Servers that provide this level of customization through APIs? Will I need to modify source of an open source NFS Server, and, if so, is there one that would be easiest to start with, and are they modularly structured such that this will be straight forward? I'm having difficult locating relevant content on the internet, and any pointers will be greatly appreciated.
IMO that kind of functionality is absolutely not the NFS server's responsibility (an nfs server should, well, serve files over nfs), but the underlying filesystem's. However, there's not that much choice in Linuxland but you could start by checking out fusecompress and btrfs.