[dm-devel] block: Fix a WRITE SAME BUG_ON

[John Dorminy]

I didn't know such a thing existed... does it work on any block
device? Where do I read more about this?

On Fri, Feb 1, 2019 at 2:35 AM Christoph Hellwig <hch at infradead.org> wrote:
>
> On Thu, Jan 31, 2019 at 02:41:52PM -0500, John Dorminy wrote:
> > > On Wed, Jan 30, 2019 at 09:08:50AM -0500, John Dorminy wrote:
> > > > (I use WRITE_SAME to fill devices with a particular pattern in order
> > > > to catch failures to initialize disk structures appropriately,
> > > > personally, but it's just for convenience/speed.)
> > >
> > > How do you use it?  We don't have a user interface to generate
> > > REQ_OP_WRITE_SAME requests.
> >
> > A not-checked-in test module, similar to Zhang Xiaoxu's reproducer,
> > exposing a sysfs node to trigger filling a block device with a test
> > pattern.
>
> Any reason you don't just use SCSI/NVMe passthrough directly from
> userspace for that?