On 1/6/06, prasad Musale <prasad.musale@xxxxxxxxx> wrote: > Hello , > Generic_file_read() reads from cached pages. That means the file pages r > already in page cache. But if I want to read file from disk, How these pages > comes in page cache. Ext2 & vfat call this generic_file_read() as their read > operation. I analyzed the sys_read() code but didn't get how file is read > from disk. Can anyone tell me about that? generic_file_read not only reads from the cache but can also do read from the physical medium (in the case of read-ahead, and cache miss) and for this it actually calls filp->mappings->a_ops->readpage or readpages .... which are the function pointers and file systems assigned it with their functions and normal file-systems like ext2 again from this function calls mpage_readpage function of kernel (AFAIR) found in mpage.c ! You can see the code of generic_file_read till calling the a_ops->readpage function and then consult file-system and the function called from it like mpage_readpage code. -- Fawad Lateef -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
