Re: [RFC] vfs: cleanup of permission()

[Herbert Poetzl <herbert@13thfloor.at>]

On Wed, Mar 01, 2006 at 12:45:44AM -0800, Trond Myklebust wrote:
> On Tue, 2006-02-28 at 06:26 +0100, Herbert Poetzl wrote:
> > Hi Andrew! Christoph! Al!
> > 
> > after thinking some time about the oracle words
> > (sent in reply to previous BME submissions) we 
> > (Sam and I) came to the conclusion that it would 
> > be a good idea to remove the nameidata introduced
> > in September 2003 from the inode permission()
> > checks, so that vfs_permission() can take care
> > of them ...
> 
> Why? There may be perfectly legitimate reasons for the filesystem to
> request information about the path. I can think of server failover
> situations in NFSv4 where the client may need to look up the
> filehandle for the file on the new server before it can service the
> ACCESS call.

the second part is actually a hack to help nfs and fuse
to get the 'required' information until there is a proper
interface (at the vfs not inode level) to pass relevant
information (probably dentry/vfsmount/flags)

> > this is in two parts, the first one does the 
> > removal and the second one fixes up nfs and fuse
> > by passing the relevant nd_flags via the mask
> > 
> > Note: this is just a suggestion, so please let
> >       us know what you think 
> 
> Firstly, the fact that the lookup intent flags happen not to collide
> with MAY_* is a complete fluke, not a design. The numerical values of
> either set of flags could change tomorrow for all you know.
>
> Secondly, an intent is _not_ a permissions mask by any stretch of the
> imagination.

see above

> IOW: at the very least make that intent flag a separate parameter.

IMHO it would be good to remove them completely form the
current permission() checks.

best,
Herbert

> Cheers,
>   Trond
> 
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