ref: 82362507f758da7cd9e31eb4b5befbb76535a596
dir: /sys/src/cmd/cfs/file.h/
void fmerge(Dptr*, char*, char*, int, int); int fbwrite(Icache*, Ibuf*, char*, ulong, int); long fwrite(Icache*, Ibuf*, char*, ulong, long); Dptr* fpget(Icache*, Ibuf*, ulong); long fread(Icache*, Ibuf*, char*, ulong, long);