On Wed, Oct 09, 2019 at 01:25:26PM -0600, Logan Gunthorpe wrote:

With passthru, the data_len is no longer guaranteed to be set
for all requests. Therefore, we should not check for it to be
non-zero. Instead check if the SGL length is zero and map
when appropriate.

None of the other transports check data_len which is verified
in core code.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>

I think the issue here is deeper.  Yes, this patch is correct, but
nvmet-tcp has another use of req.data_len in
nvmet_tcp_handle_req_failure, which looks completely bogus.  Please
try to audit that as well and send out fixes to the list separately
from this series, as both look like potentially serious bugs.