superblock         11 defs.h         struct superblock;
superblock         38 defs.h         void            readsb(int dev, struct superblock *sb);
superblock         28 fs.c           struct superblock sb; 
superblock         32 fs.c           readsb(int dev, struct superblock *sb)
superblock         59 log.c            struct superblock sb;
superblock         30 mkfs.c         struct superblock sb;