From mboxrd@z Thu Jan 1 00:00:00 1970 From: Martin Jambor Subject: File and device pages and buffers Date: Mon, 18 Apr 2005 02:09:51 +0200 Message-ID: <8e70aacf05041717093deeb825@mail.gmail.com> Reply-To: Martin Jambor Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: Received: from zproxy.gmail.com ([64.233.162.201]:55920 "EHLO zproxy.gmail.com") by vger.kernel.org with ESMTP id S261577AbVDRAJw convert rfc822-to-8bit (ORCPT ); Sun, 17 Apr 2005 20:09:52 -0400 Received: by zproxy.gmail.com with SMTP id 9so1603861nzo for ; Sun, 17 Apr 2005 17:09:51 -0700 (PDT) To: linux-fsdevel@vger.kernel.org Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org There is one thing about cache pages and buffers that puzzles me and that I have not found in any documenatation and that is not quite obvious from the source. What is the relationship between: a) pages and their buffers associated with the device (tybically bh->bdev->bd_inode and its mapping) and b) pages and their buffers associated with files on that device. I am almost certain they are not the same but at the same time the relationship seems to be quite important, otherwise we wouldn't have such dark functions as unmap_underlying_metadata (why on earth is it called this way? - Does metadata mean, in true kernel naming confusion spirit, device pages/blocks?). Can anyone tell me what the relationship exactly is and what one has to be aware of when manipulating either of these? Thank you very much in advance, Martin Jambor