Disk file system with no journaling, supports next operations:

• create - creates new file
• read - reads bytes from file with specified name
• ls - lists all files in the specified directory
• filestat - shows stat of a file wirh specified file descriptor fd
• open - opens file (adds record that current fd is being used)
• close - closes file (frees fd)
• link - makes hard link
• truncate - changes size of a file
• unlink - deletes hard link
• write - writes bytes in a file
• mkdir - creates a dir by name
• rmdir - removes dir
• pwd - shows current work dir
• cd - changes work dir to the specified one
• symlink - creates soft link