Re: [PATCH] add a FMODE flag to make XFS invisible I/O less hacky

[Christoph Hellwig <hch@lst.de>]

On Sun, Nov 30, 2008 at 10:16:04AM +0100, Christoph Hellwig wrote:
> On Fri, Nov 28, 2008 at 11:30:52AM +0000, Al Viro wrote:
> > On Fri, Nov 28, 2008 at 12:24:02PM +0100, Christoph Hellwig wrote:
> > > XFS has a mode called invisble I/O that doesn't update any of the
> > > timestamps.  It's used for HSM-style applications and exposed through
> > > the nasty open by handle ioctl.
> > > 
> > > Instead of doing directly assignment of file operations that set an
> > > internal flag for it add a new FMODE_INVISIBLE flag that we can check
> > > in the normal file operations.
> > 
> > Seeing that it's similar to O_NOATIME, why not do it in O_... space?
> 
> For now I just want to get rid of the horrible hack in XFS.  Adding this
> as a user-visible feature might be a good idea that those who need it
> can submit.

Taking about that submission, any chance I could just put in this with a
flag allocated high enough to not clash in the XFS tree and then sort
out things once the vfs and xfs trees get merged for 2.6.29?  That's
help making progress on the XFS side a lot, as there would be tons of
merge conflicts there othwerwise.  (compat_ioctl handling just got a big
rework, touch just 2/3s of the hunks of this patch)