Unexpected issues with 2 NVME initiators using the same target

[Sagi Grimberg]

> Go back and browse the end of the thread: there's no need to change
> xprtrdma, and maybe no need to change the others either.

I think there is, even with inline, xprtrdma dma maps the immediate
buffers, also the message head and tail so unmapping these buffers
without waiting for the send completion would trigger a IOMMU access
error (the HCA (re)tries to access an already unmapped buffer).