From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin Jambor" Subject: Re: File System Address Space Operations Date: Sat, 29 Jul 2006 18:30:23 +0200 Message-ID: <9615ac9b0607290930i1aa35776nfbe773c4d8e93b5c@mail.gmail.com> References: <20060729071507.59949.qmail@web37511.mail.mud.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org Return-path: Received: from ug-out-1314.google.com ([66.249.92.172]:24418 "EHLO ug-out-1314.google.com") by vger.kernel.org with ESMTP id S1751306AbWG2QaZ (ORCPT ); Sat, 29 Jul 2006 12:30:25 -0400 Received: by ug-out-1314.google.com with SMTP id m3so160368ugc for ; Sat, 29 Jul 2006 09:30:23 -0700 (PDT) To: "UZAIR LAKHANI" In-Reply-To: <20060729071507.59949.qmail@web37511.mail.mud.yahoo.com> Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On 7/29/06, UZAIR LAKHANI wrote: > Hello All, > > I want to find out the details of the address space > operations. Where can I get the detailed information > about the address space operations. Have a look at a) Documentation/filesystems/vfs.txt b) Documentation/filesystems/Locking and c) some simple fs that uses it (minix?) > In addition I want to find out whether these address space > operations are for performance reasons or are mandatory to > implement. No, I guess you could access the underlying device (or a remote server) each time a filesystem object is read or written to. This approach would be simple but a) it could be very slow (at least a block device based filesystem like that would), b) you basically wouldn't be able to implement mmap unless you wrote an equivalent of the page cache and c) when you use the generic functions to handle the file operations and only code the address space operations, it is not that much more difficult. > In addition do distributed file systems on the client > and server side require to implement address space > operations e.g. nfs (client side) implements these > address space operations. I'm not an expert on network filesystems but it would probably depend on whether and what kind of client caching you want. HTH Martin