scsi: target: pscsi: Set SCF_TREAT_READ_AS_NORMAL flag only if there is valid data

With tape devices, the SCF_TREAT_READ_AS_NORMAL flag is used by the target
subsystem to mark commands which have both data to return as well as sense
data. But with pscsi, SCF_TREAT_READ_AS_NORMAL can be set even if there is
no data to return. The SCF_TREAT_READ_AS_NORMAL flag causes the target core
to call iscsit data-in callbacks even if there is no data, which iscsit
does not support. This results in iscsit going into an error state
requiring recovery and being unable to complete the command to the
initiator.

This issue can be resolved by fixing pscsi to only set
SCF_TREAT_READ_AS_NORMAL if there is valid data to return alongside the
sense data.

Link: https://lore.kernel.org/r/20220427183250.291881-1-djeffery@redhat.com


Fixes: bd813720 ("scsi: target: transport should handle st FM/EOM/ILI reads")
Reported-by: Scott Hamilton <scott.hamilton@atos.net>
Tested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: David Jeffery <djeffery@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>