From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 24 Jun 2001 23:01:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 24 Jun 2001 23:01:39 -0400 Received: from imo-m03.mx.aol.com ([64.12.136.6]:8147 "EHLO imo-m03.mx.aol.com") by vger.kernel.org with ESMTP id ; Sun, 24 Jun 2001 23:01:31 -0400 Date: Sun, 24 Jun 2001 23:01:23 -0400 From: hunghochak@netscape.net (Ho Chak Hung) To: linux-kernel@vger.kernel.org Subject: Re: How does ramfs actually fills the page cache with data? Mime-Version: 1.0 Message-ID: <2E88A0D1.6C921C1E.0F76C228@netscape.net> X-Mailer: Franklin Webmailer 1.0 Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org thanks a lot for your reply But is it at all possible to put data into page cache without going through the inodes or files? I mean, for example, if you are given a string "abcde", and you want to allocate a page to store this "abcde" into that page and add that page to the page cache, what would you do? 2)The ramfs uses the generic file operation Ingo Oeser wrote: > > On Fri, Jun 22, 2001 at 05:45:27PM -0400, Ho Chak Hung wrote: > > In fs/ramfs/inode.c, how does ramfs actually fills the page > > cache with data? In the readpage operation, it only zero-fill > > the page if it didn't already exist in the page cache. However, > > how do I actually fill the page with data? > > The page cache does it itself. > > "readpage" is to move pages from the backing store into the page > cache. > > "writepage" and friends is for updating the backing store with > the contents of the page cache. > > There is no real backing store of ramfs, since ramfs data lives > completly in page cache. > > But we cannot give the user random memory contents, so we zero it > out on readpage and prepare_write. > > The data is copied with copy_{from,to}_user in the generic file > operations (look how ramfs_file_operations is defined and look at > the functions referenced), which read/write through page cache. > > Regards > > Ingo Oeser > -- > Use ReiserFS to get a faster fsck and Ext2 to fsck slowly and gently. > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > __________________________________________________________________ __________________________________________________________________ Get your own FREE, personal Netscape Webmail account today at http://webmail.netscape.com/