iscsi-target: Add MaxXmitDataSegmentLength connection recovery check

The iSCSI TMR TASK_REASSIGN completion logic in iscsi_tmr_task_reassign()
does an explict check for MRDSL across task reassignment, so go ahead and
add an explict MaxXmitDataSegmentLength check here as well to be safe.

Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Andy Grover <agrover@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target_core.h

@@ -579,6 +579,7 @@ struct iscsi_conn_recovery {
 	u16			cid;
 	u32			cmd_count;
 	u32			maxrecvdatasegmentlength;
+	u32			maxxmitdatasegmentlength;
 	int			ready_for_reallegiance;
 	struct list_head	conn_recovery_cmd_list;
 	spinlock_t		conn_recovery_cmd_lock;

drivers/target/iscsi/iscsi_target_erl2.c

@@ -421,6 +421,7 @@ int iscsit_prepare_cmds_for_realligance(struct iscsi_conn *conn)
 	cr->cid = conn->cid;
 	cr->cmd_count = cmd_count;
 	cr->maxrecvdatasegmentlength = conn->conn_ops->MaxRecvDataSegmentLength;
+	cr->maxxmitdatasegmentlength = conn->conn_ops->MaxXmitDataSegmentLength;
 	cr->sess = conn->sess;
 
 	iscsit_attach_inactive_connection_recovery_entry(conn->sess, cr);

drivers/target/iscsi/iscsi_target_tmr.c

@@ -146,7 +146,7 @@ u8 iscsit_tmr_task_reassign(
 	}
 	/*
 	 * Temporary check to prevent connection recovery for
-	 * connections with a differing MaxRecvDataSegmentLength.
+	 * connections with a differing Max*DataSegmentLength.
 	 */
 	if (cr->maxrecvdatasegmentlength !=
 	    conn->conn_ops->MaxRecvDataSegmentLength) {
@@ -155,6 +155,13 @@ u8 iscsit_tmr_task_reassign(
 			" TMR TASK_REASSIGN.\n");
 		return ISCSI_TMF_RSP_REJECTED;
 	}
+	if (cr->maxxmitdatasegmentlength !=
+	    conn->conn_ops->MaxXmitDataSegmentLength) {
+		pr_err("Unable to perform connection recovery for"
+			" differing MaxXmitDataSegmentLength, rejecting"
+			" TMR TASK_REASSIGN.\n");
+		return ISCSI_TMF_RSP_REJECTED;
+	}
 
 	ref_lun = scsilun_to_int(&hdr->lun);
 	if (ref_lun != ref_cmd->se_cmd.orig_fe_lun) {