ceph: try to dump the msgs when decoding fails

When the msgs are corrupted we need to dump them and then it will
be easier to dig what has happened and where the issue is.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Milind Changire <mchangir@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/mds_client.c

@@ -645,6 +645,7 @@ static int parse_reply_info(struct ceph_mds_session *s, struct ceph_msg *msg,
 	err = -EIO;
 out_bad:
 	pr_err("mds parse_reply err %d\n", err);
+	ceph_msg_dump(msg);
 	return err;
 }
 
@@ -3538,6 +3539,7 @@ static void handle_forward(struct ceph_mds_client *mdsc,
 
 bad:
 	pr_err("mdsc_handle_forward decode error err=%d\n", err);
+	ceph_msg_dump(msg);
 }
 
 static int __decode_session_metadata(void **p, void *end,
@@ -5258,6 +5260,7 @@ void ceph_mdsc_handle_fsmap(struct ceph_mds_client *mdsc, struct ceph_msg *msg)
 bad:
 	pr_err("error decoding fsmap %d. Shutting down mount.\n", err);
 	ceph_umount_begin(mdsc->fsc->sb);
+	ceph_msg_dump(msg);
 err_out:
 	mutex_lock(&mdsc->mutex);
 	mdsc->mdsmap_err = err;
@@ -5326,6 +5329,7 @@ void ceph_mdsc_handle_mdsmap(struct ceph_mds_client *mdsc, struct ceph_msg *msg)
 bad:
 	pr_err("error decoding mdsmap %d. Shutting down mount.\n", err);
 	ceph_umount_begin(mdsc->fsc->sb);
+	ceph_msg_dump(msg);
 	return;
 }