[PATCH] nvme/pci: Fix HMB size calculation

[Keith Busch]

On Tue, Jul 18, 2017 at 07:39:54PM +0200, Christoph Hellwig wrote:
> On Mon, Jul 17, 2017 at 07:45:39PM -0400, Keith Busch wrote:
> > It's possible the preferred HMB size may not be a multiple of the
> > chunk_size. This patch will set the chunk_size to the descriptor's actual
> > length so the last iteration doesn't cause the total size to exceed the
> > allocated HMB size.
> 
> This looks a little weird, and might do the wrong thing
> if we hit the retry loop after reducing chunk_size.

It may look weird when you consider the retry, but I'm pretty sure it
isn't wrong. The only way you can get to the retry is if the for-loop
breaks before the last interation, which means chunk_size will be
unchanged. That's not immediately obvious, though, so maybe this
implementation was trying to be too clever.
 
> I suspect we just need to change to
> 
> 	for (size = 0; size < preferred; size += len) {
> 
> and move len to function scope.

That's fine too.