scsi: lpfc: raise sg count for nvme to use available sg resources

The driver allocates a sg list per io struture based on a fixed maximum
size. When it registers with the protocol transports and indicates the max sg
list size it supports, the driver manipulates the fixed value to report a
lesser amount so that it has reserved space for sg elements that are used for
DIF.

The driver initialization path sets the cfg_sg_seg_cnt field to the
manipulated value for scsi. NVME initialization ran afterward and capped it's
maximum by the manipulated value for SCSI. This erroneously made NVME report
the SCSI-reduce-for-DIF value that reduced the max io size for nvme and wasted
sg elements.

Rework the driver so that cfg_sg_seg_cnt becomes the overall maximum size and
allow the max size to be tunable.  A separate (new) scsi sg count is then
setup with the scsi-modified reduced value. NVME then initializes based off
the overall maximum.

Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/lpfc/lpfc_nvmet.c

@@ -1373,17 +1373,10 @@ lpfc_nvmet_create_targetport(struct lpfc_hba *phba)
 	pinfo.port_name = wwn_to_u64(vport->fc_portname.u.wwn);
 	pinfo.port_id = vport->fc_myDID;
 
-	/* Limit to LPFC_MAX_NVME_SEG_CNT.
-	 * For now need + 1 to get around NVME transport logic.
+	/* We need to tell the transport layer + 1 because it takes page
+	 * alignment into account. When space for the SGL is allocated we
+	 * allocate + 3, one for cmd, one for rsp and one for this alignment
 	 */
-	if (phba->cfg_sg_seg_cnt > LPFC_MAX_NVME_SEG_CNT) {
-		lpfc_printf_log(phba, KERN_INFO, LOG_NVME | LOG_INIT,
-				"6400 Reducing sg segment cnt to %d\n",
-				LPFC_MAX_NVME_SEG_CNT);
-		phba->cfg_nvme_seg_cnt = LPFC_MAX_NVME_SEG_CNT;
-	} else {
-		phba->cfg_nvme_seg_cnt = phba->cfg_sg_seg_cnt;
-	}
 	lpfc_tgttemplate.max_sgl_segments = phba->cfg_nvme_seg_cnt + 1;
 	lpfc_tgttemplate.max_hw_queues = phba->cfg_nvme_io_channel;
 	lpfc_tgttemplate.target_features = NVMET_FCTGTFEAT_READDATA_RSP;