[PATCH 1/3] mm: Don't blindly assign fallback_migrate_page()

[Andrew Morton]

On Thu, 16 Jun 2016 23:26:13 +0200 Richard Weinberger <richard at nod.at> wrote:

> While block oriented filesystems use buffer_migrate_page()
> as page migration function other filesystems which don't
> implement ->migratepage() will automatically get fallback_migrate_page()
> assigned. fallback_migrate_page() is not as generic as is should
> be. Page migration is filesystem specific and a one-fits-all function
> is hard to achieve. UBIFS leaned this lection the hard way.
> It uses various page flags and fallback_migrate_page() does not
> handle these flags as UBIFS expected.
> 
> To make sure that no further filesystem will get confused by
> fallback_migrate_page() disable the automatic assignment and
> allow filesystems to use this function explicitly if it is
> really suitable.

hm, is there really much point in doing this?  I assume it doesn't
actually affect any current filesystems?

[2/3] is of course OK - please add it to the UBIFS tree.