[SCSI] fcoe: Unable to select the exchangeID from offload pool for storage targets

Problem: When initiator sends write command to target, target tries to
assign new sequence. It allocates new exchangeID (RX_ID)
always from non-offloaded pool (Non-offload EMA)

Fix: Enhanced fcoe_oem_match routine to look at F_CTL flags and if it
is exchange responder and command type is WRITEDATA, then function
returns TRUE instead of FALSE. This function is used to determine
which pool to use (offload pool of exchange is used only if this
function returns TRUE).

Technical Notes: N/A
Signed-off-by: NKiran Patil <kiran.patil@intel.com>
Signed-off-by: NRobert Love <robert.w.love@intel.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

drivers/scsi/fcoe/fcoe.c

@@ -751,12 +751,27 @@ static int fcoe_shost_config(struct fc_lport *lport, struct device *dev)
  * The offload EM that this routine is associated with will handle any
  * packets that are for SCSI read requests.
  *
+ * This has been enhanced to work when FCoE stack is operating in target
+ * mode.
+ *
  * Returns: True for read types I/O, otherwise returns false.
  */
 bool fcoe_oem_match(struct fc_frame *fp)
 {
-	return fc_fcp_is_read(fr_fsp(fp)) &&
-		(fr_fsp(fp)->data_len > fcoe_ddp_min);
+	struct fc_frame_header *fh = fc_frame_header_get(fp);
+	struct fcp_cmnd *fcp;
+
+	if (fc_fcp_is_read(fr_fsp(fp)) &&
+	    (fr_fsp(fp)->data_len > fcoe_ddp_min))
+		return true;
+	else if (!(ntoh24(fh->fh_f_ctl) & FC_FC_EX_CTX)) {
+		fcp = fc_frame_payload_get(fp, sizeof(*fcp));
+		if (ntohs(fh->fh_rx_id) == FC_XID_UNKNOWN &&
+		    fcp && (ntohl(fcp->fc_dl) > fcoe_ddp_min) &&
+		    (fcp->fc_flags & FCP_CFL_WRDATA))
+			return true;
+	}
+	return false;
 }
 
 /**