fs/smartfs: Add logic needed to ftruncate to shrink a file to any arbitrary size.
fs/smartfs: Repartition some functionality to better fit in new ftruncate features.
fs/nxffs: Add partial implementation of the truncate method: It extend files, but cannot yet shrink them.
fs/smartfs: Add partial implementation of the truncate method: It extend files, but cannot yet shrink them.
fs/fat: Add partial implementation of the truncate method: It extend files, but no yet shrink them.
fs/nfs: Add support for the truncate method to the NFS file system.
