Re: [PATCH v4 4/5] cramfs: add mmap support

[Christoph Hellwig]

On Tue, Oct 03, 2017 at 11:30:50AM -0400, Nicolas Pitre wrote:
> Unless you have a better scheme altogether  to suggest of course, given 
> the existing constraints.

I still can't understand why this convoluted fault path that finds
vma, attempts with all kinds of races and then tries to update things
like vm_ops is even nessecary.

We have direct mappings of physical address perfectly working in the
DAX code (even with write support!) or in drivers using remap_pfn_range
so a really good explanation why neither scheme can be used is needed
first.