Re: [PATCH v2 5/5] dax: handle media errors in dax_do_io

[hch@xxxxxxxxxxxxx]

On Sat, Apr 23, 2016 at 06:08:37PM +0000, Verma, Vishal L wrote:
> direct_IO might fail with -EINVAL due to misalignment, or -ENOMEM due
> to some allocation failing, and I thought we should return the original
> -EIO in such cases so that the application doesn't lose the information
> that the bad block is actually causing the error.

EINVAL is a concern here.  Not due to the right error reported, but
because it means your current scheme is fundamentally broken - we
need to support I/O at any alignment for DAX I/O, and not fail due to
alignbment concernes for a highly specific degraded case.

I think this whole series need to go back to the drawing board as I
don't think it can actually rely on using direct I/O as the EIO
fallback.