The only thing about the file not included in the inode is the name of the file. This is important, both to the concept of links and to disentangle it from directory management. Finally, directories bring the organization to a close, providing the linked list, referred to above. Thus, the superblock provides the mapping to the root directory, and from there one can find any other file on the filesystem. Data are not actually read from disk for every read request made by a user, and they are not written to disk for every write request made by a user.
Data pass through buffers on their way to and from disks.
When a user program opens and reads from a file, more data are actually read from disk than were requested, and the extra data are stored in a buffer. Subsequent read requests are fulfilled from the buffer until the buffer is empty. Then, the buffer is filled by another read from the disk. When writing to files, data are written into a buffer until the buffer fills, and then, the contents of the buffer is written to disk. Most Unix systems run a daemon that regularly flushes buffers.