linux-kernel - Re: [RFC 04/10] Temporary struct vfs_lookup in file

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Date:	Wed, 8 Aug 2007 20:56:20 +0200
From:	Andreas Gruenbacher <agruen@...e.de>
To:	Josef Sipek <jsipek@....cs.sunysb.edu>
Cc:	linux-kernel@...r.kernel.org, John Johansen <jjohansen@...e.de>,
	Jan Blunck <jblunck@...e.de>, Erez Zadok <ezk@...sunysb.edu>,
	"Josef 'Jeff' Sipek" <jsipek@...sunysb.edu>
Subject: Re: [RFC 04/10] Temporary struct vfs_lookup in file_permission

On Wednesday 08 August 2007 19:58, Josef Sipek wrote:
> On Wed, Aug 08, 2007 at 07:16:26PM +0200, Andreas Gruenbacher wrote:
> > Create a temporary struct vfs_lookup in file_permission() instead of
> > passing a NULL value.
> > 
> > Signed-off-by: Andreas Gruenbacher <ag@...tbits.at>
> > 
> > ---
> >  fs/namei.c |   11 ++++++-----
> >  1 file changed, 6 insertions(+), 5 deletions(-)
> > 
> > --- a/fs/namei.c
> > +++ b/fs/namei.c
> > @@ -292,14 +292,15 @@ int vfs_permission(struct vfs_lookup *lo
> >   *
> >   * Used to check for read/write/execute permissions on an already opened
> >   * file.
> > - *
> > - * Note:
> > - *	Do not use this function in new code.  All access checks should
> > - *	be done using vfs_permission().
> 
> Should this comment be removed?

IMO yes. If vfs_permission() works for a piece of code it's the obvious 
preference. If on the other hand you really need to check permissions on a 
file, then why not use this function?

> >   */
> >  int file_permission(struct file *file, int mask)
> >  {
> > -	return permission(file->f_path.dentry->d_inode, mask, NULL);
> > +	struct vfs_lookup lookup;
> > +
> > +	lookup.path = file->f_path;
> > +	lookup.flags = 0;
> 
> I tend to find this little bit cleaner:
> 
> struct vfs_lookup lookup = {
> 	.path	= file->f_path,
> 	.flags	= 0,
> };

I didn't use initializers because they initialize the entire data structure. 
In case of struct vfs_lookup, unless the LOOKUP_OPEN flag is set, then the 
open_intent doesn't need initialization. We could use a DEFINE_... macro; not 
sure this would improve anything though.

> > +
> > +	return permission(file->f_path.dentry->d_inode, mask, &lookup);
> >  }
> >  
> >  /*

Thanks,
Andreas
-
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