disable large folios for shmem file used by xfs xfile

[Christoph Hellwig]

On Wed, Jan 10, 2024 at 12:37:18PM +0000, Matthew Wilcox wrote:
> On Wed, Jan 10, 2024 at 10:21:07AM +0100, Christoph Hellwig wrote:
> > Hi all,
> > 
> > Darrick reported that the fairly new XFS xfile code blows up when force
> > enabling large folio for shmem.  This series fixes this quickly by disabling
> > large folios for this particular shmem file for now until it can be fixed
> > properly, which will be a lot more invasive.
> > 
> > I've added most of you to the CC list as I suspect most other users of
> > shmem_file_setup and friends will have similar issues.
> 
> The graphics users _want_ to use large folios.  I'm pretty sure they've
> been tested with this.  It's just XFS that didn't know about this
> feature of shmem.

At least sgx has all kinds of PAGE_SIZE assumptions.  I haven't audited
(and am probably not qualified to) audit that code, so I wanted to send
a headsup to everyone.