routine file_getfh (
    file: file_t;
    RPT
    out filehandle: data_t, dealloc);

Return a file handle for this file. This can be used by NFS and such. It is not guaranteed that this call will work; if it doesn't, then this filesystem cannot be NFS mounted.

Currently file handles are only used by nfsd with the purpose of having some stable representation of nodes (TODO: Add references). The only translator library that implements file_getfh and the complementary fsys getfile is libdiskfs, so if you are linking against a different library you should expect that the filesystem exported by your translator will not be supported by nfsd by default.

If you would like your non-libdiskfs translator to be supported by nfsd, you should implement these two RPCs on your own. The idea is that to each node exported by your translator you should put in correspondence a unique file handle. A file handle is a 28-byte value. The first 4 bytes are not used. Then comes a 4-byte number which should identify your node somehow (libdiskfs uses the index into the internally maintained node cache). After it there comes a 4-byte number which should bear a similar function to the st_gen field of a stat structure. Following this specification, you should be able to implement file_getfh and fsys_getfile in a proper way to get nfsd support.