Structs starting with 'f' in sys

• fid sys/mount.h:45
• file sys/file.h:45
• filedesc sys/filedesc.h:54
• filedesc0 sys/filedesc.h:70
• fileops sys/file.h:55
• flock sys/fcntl.h:151
• format_op sys/disklabel.h:277