title: Read/Write block directly to disk in linux kernel
body: <p>As the title has said, I'm looking for how I can read/write blocks directly to disk in linux kernel space (bypassing the file system) and directly interact with block IO layer. </p>
  
  <p>After reading through some kernel codes, I realize bio is the structure I should be using to achieve such goal in block IO layer. But I don't quite understand the structures of bio and haven't figure out how exactly I can do that. </p>
  
  <p>Any helps? Thank you</p>