I"ve just found out, that something went wrong in the upgrading from 9.0 to 9.1.
On 9.0, I could mount enhanced CD-t data track. After upgrading, I cannot.

I've seen all of the problems, written in that old thread:

http://lists.freebsd.org/pipermail/freebsd-current/2009-April/005826.html

Eg: "cdcontrol info" shows the length of the last audio track irreally long:

$ cdcontrol info
Starting track = 1, ending track = 24, TOC size = 202 bytes
track     start  duration   block  length   type
-------------------------------------------------
    1   0:02.00   0:22.49       0    1699  audio
    2   0:24.49   1:44.25    1699    7825  audio
    3   2:08.74   1:30.49    9524    6799  audio
    4   3:39.48   1:00.41   16323    4541  audio
    5   4:40.14   1:39.35   20864    7460  audio
    6   6:19.49   1:32.54   28324    6954  audio
    7   7:52.28   1:41.37   35278    7612  audio
    8   9:33.65   1:36.09   42890    7209  audio
    9  11:09.74   1:41.21   50099    7596  audio
   10  12:51.20   1:38.54   57695    7404  audio
   11  14:29.74   1:43.28   65099    7753  audio
   12  16:13.27   1:27.05   72852    6530  audio
   13  17:40.32   1:38.65   79382    7415  audio
   14  19:19.22   1:45.72   86797    7947  audio
   15  21:05.19   1:47.38   94744    8063  audio
   16  22:52.57   1:22.61  102807    6211  audio
   17  24:15.43   1:55.10  109018    8635  audio
   18  26:10.53   1:51.52  117653    8377  audio
   19  28:02.30   1:44.65  126030    7865  audio
   20  29:47.20   1:14.09  133895    5559  audio
   21  31:01.29   1:46.10  139454    7960  audio
   22  32:47.39   1:32.74  147414    6974  audio
   23  34:20.38   4:23.12  154388   19737  audio
   24  38:43.50   5:46.70  174125   26020   data
  170  44:30.45         -  200145       -      -
$ 

and the same CD from "cdda2wav -info-only" :

$  cdda2wav -info-only
No target specified, trying to find one...
Using dev=1,0,0.
Type: ROM, Vendor 'HL-DT-ST' Model 'DVDRAM GSA-T20L ' Revision 'NC08' MMC+CDDA
307200 bytes buffer memory requested, transfer size 65536 bytes, 4 buffers, 27 sectors
#Cdda2wav version 3.00_freebsd_9.0-release-p3_i386_i386, real time sched., soundcard, libparanoia support
AUDIOtrack pre-emphasis  copy-permitted tracktype channels
      1-23           no              no     audio    2
 DATAtrack recorded      copy-permitted tracktype
     24-24 uninterrupted             no      data
Table of Contents: total tracks:24, (total time 44:28.45)
  1.( 0:22.49),  2.( 1:44.25),  3.( 1:30.49),  4.( 1:00.41),  5.( 1:39.35),
  6.( 1:32.54),  7.( 1:41.37),  8.( 1:36.09),  9.( 1:41.21), 10.( 1:38.54),
 11.( 1:43.28), 12.( 1:27.05), 13.( 1:38.65), 14.( 1:45.72), 15.( 1:47.38),
 16.( 1:22.61), 17.( 1:55.10), 18.( 1:51.52), 19.( 1:44.65), 20.( 1:14.09),
 21.( 1:46.10), 22.( 1:32.74), 23.| 1:51.12|, 24.[ 5:46.70]

Table of Contents: starting sectors
  1.(       0),  2.(    1699),  3.(    9524),  4.(   16323),  5.(   20864),
  6.(   28324),  7.(   35278),  8.(   42890),  9.(   50099), 10.(   57695),
 11.(   65099), 12.(   72852), 13.(   79382), 14.(   86797), 15.(   94744),
 16.(  102807), 17.(  109018), 18.(  117653), 19.(  126030), 20.(  133895),
 21.(  139454), 22.(  147414), 23.(  154388), 24.(  174125), lead-out(  200145)
CDINDEX discid: NXTPFwVidQ4j8hmvd.czc_G9d2o-
CDDB discid: 0x560a6c18
CD-Text: not detected
CD-Extra: not detected
No media catalog number present.
scanning for ISRCs: 23 ...
index scan: 23...

cdparanoia tries to grab the last audio track, but got so many scsi error messages eg:
$ cdparanoia -B 23
cdparanoia III release 9.8 (March 23, 2001)
(C) 2001 Monty <monty@xiph.org> and Xiphophorus
FreeBSD porting (c) 2003
	Simon 'corecode' Schubert <corecode@corecode.ath.cx>

Report bugs to paranoia@xiph.org
http://www.xiph.org/paranoia/

Ripping from sector  154388 (track 23 [0:00.00])
	  to sector  174124 (track 23 [4:23.11])

outputting to track23.cdda.wav

 (== PROGRESS == [                      >       | 169342 00 ] == :-) . ==)   scsi_read error: sector=169475 length=26 retry=0
                 Sense key: 3 ASC: 11 ASCQ: 0
                 Transport error: Medium reading data from medium
                 System error: Input/output error

scsi_read error: sector=169475 length=13 retry=1
                 Sense key: 3 ASC: 10 ASCQ: 0
                 Transport error: Medium reading data from medium
                 System error: Input/output error

(cdda2wav - as reported in that thread - can grab the last audio track without
any error.)

But (my) main problem, is that I cannot mount the data track (actually, I did it with 9.0)

I tested it with some of the Oxford University Press's New English File CD-s. (I used to mount on 9.0, and I can mount them under Linux now.)

How-To-Repeat: Get an enhanced CD, and try to mount the data track.