ref: 692ad10eaf686fa457a6e2e9f81a41c4fd4d3981
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);