cannot mount later cdrom sessions with 2.4.x

[David Wragg <dpw@doc.ic.ac.uk>]

Is multisession CDROM support broken in 2.4.x?

I have an "Enhanced CD" which has a bunch of audio tracks followed by
a data track (is this the same as CD-XA? I can't remember).  Under
2.2, I can mount the iso9660 filesystem on the data track without
trouble, using the session option:

# mount -o session=19 /mnt/cdrom

But under 2.4.2, the mount fails with this in the kernel log:

Session 20 start 230045 type 4
attempt to access beyond end of device
16:00: rw=0, want=460123, limit=61884
isofs_read_super: bread failed, dev=16:00, iso_blknum=230061, block=460122

It looks like the blk_size entry doesn't get updated to reflect the
fact that isofs has issued an ioctl to switch to a later session on
the disc.

The drive I'm using is:
hdc: MATSHITADVD-ROM SR-8174, ATAPI CD/DVD-ROM drive

Dave Wragg
(hoping that the QuickTime movies on the data track use an xanim
supported codec, but not optimistic)