RDMA/srp: Propagate ib_post_send() failures to the SCSI mid-layer

This patch avoids that the SCSI mid-layer keeps retrying forever if
ib_post_send() fails. This was discovered while testing immediate
data support and passing a too large num_sge value to ib_post_send().

Cc: Sergey Gorenko <sergeygo@mellanox.com>
Cc: Max Gurtovoy <maxg@mellanox.com>
Cc: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/srp/ib_srp.c

@@ -2358,6 +2358,7 @@ static int srp_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *scmnd)
 
 	if (srp_post_send(ch, iu, len)) {
 		shost_printk(KERN_ERR, target->scsi_host, PFX "Send failed\n");
+		scmnd->result = DID_ERROR << 16;
 		goto err_unmap;
 	}