Comment # 1 on bug 971549 from Gang He

sometimes we can see IO error message, even let the file system become
read-only status.
the journal messages likes,
ar 17 16:47:00 tb-node3 iscsid[1360]: iscsid: connection1:0 is operational
after recovery (1 attempts)
Mar 17 16:47:01 tb-node3 kernel: JBD2: Detected IO errors while flushing file
data on dm-0-109
Mar 17 16:47:01 tb-node3 kernel:  connection1:0: detected conn error (1020)
Mar 17 16:47:01 tb-node3 iscsid[1360]: iscsid: Kernel reported iSCSI connection
1:0 error (1020 - ISCSI_ERR_TCP_CONN_CLOSE: TCP connection closed) state (3)
Mar 17 16:47:03 tb-node3 iscsid[1360]: iscsid: connection1:0 is operational
after recovery (1 attempts)
Mar 17 16:47:04 tb-node3 iscsid[1360]: iscsid: Kernel reported iSCSI connection
1:0 error (1020 - ISCSI_ERR_TCP_CONN_CLOSE: TCP connection closed) state (3)
Mar 17 16:47:04 tb-node3 kernel:  connection1:0: detected conn error (1020)
Mar 17 16:47:06 tb-node3 iscsid[1360]: iscsid: connection1:0 is operational
after recovery (1 attempts)
Mar 17 16:47:07 tb-node3 kernel: JBD2: Detected IO errors while flushing file
data on dm-0-109
Mar 17 16:47:07 tb-node3 kernel:  connection1:0: detected conn error (1020)
Mar 17 16:47:07 tb-node3 iscsid[1360]: iscsid: Kernel reported iSCSI connection
1:0 error (1020 - ISCSI_ERR_TCP_CONN_CLOSE: TCP connection closed) state (3)
Mar 17 16:47:09 tb-node3 iscsid[1360]: iscsid: connection1:0 is operational
after recovery (1 attempts)
Mar 17 16:47:10 tb-node3 iscsid[1360]: iscsid: Kernel reported iSCSI connection
1:0 error (1020 - ISCSI_ERR_TCP_CONN_CLOSE: TCP connection closed) state (3)
Mar 17 16:47:10 tb-node3 kernel:  connection1:0: detected conn error (1020)
Mar 17 16:47:12 tb-node3 iscsid[1360]: iscsid: connection1:0 is operational
after recovery (1 attempts)
Mar 17 16:47:13 tb-node3 kernel: JBD2: Detected IO errors while flushing file
data on dm-0-109
Mar 17 16:47:13 tb-node3 kernel:  connection1:0: detected conn error (1020)