From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@lst.de>
Subject: Re: reiser4 plugins (was: silent semantic changes with reiser4)
Date: Thu, 26 Aug 2004 18:06:01 +0200
Message-ID: <20040826160601.GB4326@lst.de>
References: <20040826124929.GA542@lst.de> <1093525234.9004.55.camel@leto.cs.pocnet.net> <20040826130718.GB820@lst.de> <1093526273.11694.8.camel@leto.cs.pocnet.net> <20040826132439.GA1188@lst.de> <1093527307.11694.23.camel@leto.cs.pocnet.net> <20040826134034.GA1470@lst.de> <1093528683.11694.36.camel@leto.cs.pocnet.net> <20040826153748.GA3700@lst.de> <1093535334.5482.1.camel@leto.cs.pocnet.net>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Christoph Hellwig <hch@lst.de>, Andrew Morton <akpm@osdl.org>,
   Hans Reiser <reiser@namesys.com>, linux-fsdevel@vger.kernel.org,
   linux-kernel@vger.kernel.org, flx@namesys.com, torvalds@osdl.org,
   reiserfs-list@namesys.com
Return-path: <reiserfs-list-return-20710-reiserfs=m.gmane.org@namesys.com>
list-help: <mailto:reiserfs-list-help@namesys.com>
list-unsubscribe: <mailto:reiserfs-list-unsubscribe@namesys.com>
list-post: <mailto:reiserfs-list@namesys.com>
Errors-To: flx@namesys.com
To: Christophe Saout <christophe@saout.de>
Content-Disposition: inline
In-Reply-To: <1093535334.5482.1.camel@leto.cs.pocnet.net>
List-Id: linux-fsdevel.vger.kernel.org

On Thu, Aug 26, 2004 at 05:48:54PM +0200, Christophe Saout wrote:
> > > I don't know, ask Hans. How could the VFS know it a filesystem wants to
> > > do something specific with a file that is completely transparent to the
> > > VFS?
> > 
> > The VFS shouldn't, that the whole point.  That's why it allows the
> > filesystem to register different method tables for each object.
> 
> Only the objects it can distinguish.

Yes, every inode can have different operation vectors.  Which is the
smallest possible object the VFS knows about.

> >         ops->file    = reiser4_file_operations;
> >         ops->symlink = reiser4_symlink_inode_operations;
> >         ops->special = reiser4_special_inode_operations;
> >         ops->dentry  = reiser4_dentry_operations;
> >         ops->as      = reiser4_as_operations;
> 
> How could reiser4 register other operations for files that should be
> stored encrypted or compressed? It's all under reiser4_file_operations.

Again, your confusing upper and lower plugins.  For things happening
below the pagecache you could register different address_space
operations which sometimes makes sense.  But you want e.g. different
inode_operations for directories vs symlinks vs files.

Please read through some linux filesystem code, okay :)