Internals of ext2fs

ext2fs Superblock

ext2_read_super actually reads the superblock data into memory:

     struct super_block * ext2_read_super (struct super_block * sb, void * data,
                                           int silent)
        unsigned long logic_sb_block = 1;

        ...   
        if (!(bh = bread (dev, logic_sb_block, blocksize))) {
                   printk ("EXT2-fs: unable to read superblock\n");
                   return NULL;
           }
        ...

bread here actually reads the disk
- (It too is dispatched through a method table for the particular physical device)
dev identifies the device
logic_sb_block is the block number to read---normally 1
- Because the superblock is normally the first block on the disk