2.6.14.4 ide-tape not noticing filemarks

[Richard Kettlewell <rjk@greenend.org.uk>]

I have a Seagate/Certance ATAPI tape drive, reported thus:

ide-tape: hdd <-> ht0: Seagate STT20000A rev 8A51
ide-tape: hdd <-> ht0: 1000KBps, 6*54kB buffer, 9720kB pipeline, 110ms tDSC, DMA

I've been using this with ide-scsi in Linux 2.4.31 for my backups.  It
worked OK.

I upgraded to 2.6.14.4 and it seem to have lost the ability to detect
filemarks.  This happens whether I use it via ide-scsi or use the
ide-tape interface directly.

  sfere# mt -f /dev/nht0 rewind
  sfere# dd if=foo of=/dev/nht0 bs=512 count=1
  1+0 records in
  1+0 records out
  512 bytes transferred in 28.162633 seconds (18 bytes/sec)
  sfere# dd if=foo of=/dev/nht0 bs=512 count=1
  1+0 records in
  1+0 records out
  512 bytes transferred in 5.520161 seconds (93 bytes/sec)
  sfere# mt -f /dev/nht0 rewind
  sfere# dd if=/dev/nht0 of=bar bs=512 count=2
  2+0 records in
  2+0 records out
  1024 bytes transferred in 6.392595 seconds (160 bytes/sec)
  sfere# mt -f /dev/nht0 status
  drive type = Generic SCSI-2 tape
  drive status = 512
  sense key error = 0
  residue count = 0
  file number = 0
  block number = 4
  Tape block size 512 bytes. Density code 0x0 (default).
  Soft error count since last status=0
  General status bits on (0):

Am I doing something wrong somewhere, or has ide-tape stopped noticing
filemarks reliably/at all?

(I see the same problem on tapes written under 2.4.31 but read under
2.6.14.4, which is why I think it's a problem with reading and not
writing.)

ttfn/rjk
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