Page migration issue with UBIFS

[Christoph Hellwig]

On Wed, Mar 16, 2016 at 05:21:56PM +0300, Kirill A. Shutemov wrote:
> > FYI, with a dummy ->migratepage() which returns only -EINVAL UBIFS does no
> > longer explode upon page migration.
> > Tomorrow I'll do more tests to make sure.
> 
> Could you check if something like this would fix the issue.
> Completely untested.

We really need to make the default safe for file systems that don't
have a migratepage method.