Re: [PATCH] Return short read or 0 at end of a raw device, not EIO

Christoph Hellwig
2014-09-30T15:28:45Z

On Mon, Sep 29, 2014 at 06:08:11PM -0400, David Jeffery wrote:
> On 09/29/2014 03:05 PM, Christoph Hellwig wrote:
> > Seems like this should be changed in the generic code, or is there some
> > reason why it would return EIO only for devices, but not for regular
> > files in this case?
> >
>
> Regular files shouldn't be returning EIO and don't in my tests. The file
> systems manage direct I/O EOF handling in their own block or direct_IO
> callbacks. Block devices do not and instead do the size checks up
> front. Raw devices were bypassing the block device check, so only the
> raw driver should be having this issue.

So I guess the problem is commit

"blkdev_aio_read(): switch to generic_file_read_iter(), get rid of iov_shorten()"

which removes the iov_shorten call in blkdev_aio_read? This should be
mentioned in the changelog.

But maybe we should instead make block devices behave more similar to
regular files in this respect?

Also did you make sure to add your regression test somewhere, e.g. ltp?