Mastering Linux Kernel Development

File read and write operations

When user applications initiate read on a file with appropriate arguments, the underlying filesystem's read routine is invoked. Operations begin with a lookup into the file's data block map to locate the appropriate data disk sector to be read; it then allocates a page from the page cache and schedules disk I/O. On completion of I/O transfer, the filesystem moves requested data into the application's buffer and updates the file offset position in the caller's file descriptor structure.

Similarly, the write operation of the filesystem retrieves data passed from user buffer and writes it into the appropriate offset of file buffer in the page cache, and marks the page with the PG_dirty flag. However, when the ...