Re: [MiNT] FreeMiNT & MiNTlib patchset - add new support

[Alan Hourihane <alanh@fairlite.co.uk>]

On Wed, 2008-08-20 at 12:00 +0200, Frank Naumann wrote:
> Hello!
> 
> >>>> This avoid any modification on the xfs, we don't have any compatibility
> >>>> problems and the directories are handled generically inside the kernel.
> >>>
> >>> Without adding a new flag to the XFS module to detect an older XFS, I'm
> >>> not sure how adding additional checks for EISDIR into the kernel
> >>> filesystem layer can help.
> >>
> >> If you can move the two modifications inside the xfs into the upper layer
> >> you don't need to modify the xfs at all. I think that's much better.
> >
> > I still dont understand how you can do this.
> >
> > The kernel is allowing read-only directories through to the XFS.
> >
> > How is the filesystem layer meant to know to refuse that with an older
> > XFS ??
> 
> You don't get my idea. If you don't modify the xfs at all there exist no 
> "old" or "new" xfs, they are untouched and thus no compatibility issue.
> 
> You only need to handle these two things inside Fopen() and Fread().

Actually, now I remembered why I didn't do it this way.

We add additional xfs_getxattr() call on every read/write/lseek/etc to
obtain the attributes to determine whether it's a directory or not,
which I'm not sure how much slowdown that can cause for normal
operations.

By letting it hit the filesystem, that data is already known.

But I'll go with your suggestion.

Alan.