Get tape device lock with interrupts disabled. Otherwise lockdep will issue a
warning similar to:

=================================
[ INFO: inconsistent lock state ]
2.6.27 #1
---------------------------------
inconsistent {in-hardirq-W} -> {hardirq-on-W} usage.
vol_id/2903 [HC0[0]:SC0[0]:HE1:SE1] takes:
 (sch->lock){++..}, at: [<000003e00004c7a2>] tape_open+0x42/0x1a4 [tape]
{in-hardirq-W} state was registered at:
  [<000000000007ce5c>] __lock_acquire+0x894/0xa74
  [<000000000007d0ce>] lock_acquire+0x92/0xb8
  [<0000000000345154>] _spin_lock+0x5c/0x9c
  [<0000000000202264>] do_IRQ+0x124/0x1f0
  [<0000000000026610>] io_return+0x0/0x8

irq event stamp: 847
hardirqs last  enabled at (847): [<000000000007aca6>] trace_hardirqs_on+0x2a/0x38
hardirqs last disabled at (846): [<0000000000076ca2>] trace_hardirqs_off+0x2a/0x38
softirqs last  enabled at (0): [<000000000004909e>] copy_process+0x43e/0x11f4
softirqs last disabled at (0): [<0000000000000000>] 0x0

other info that might help us debug this:
1 lock held by vol_id/2903:
 #0:  (&bdev->bd_mutex){--..}, at: [<000000000010e0f4>] do_open+0x78/0x358

stack backtrace:
CPU: 1 Not tainted 2.6.27 #1},
Process vol_id (pid: 2903, task: 000000003d4c0000, ksp: 000000003d4e3b10)
0400000000000000 000000003d4e3830 0000000000000002 0000000000000000
       000000003d4e38d0 000000003d4e3848 000000003d4e3848 00000000000168a8
       0000000000000000 000000003d4e3b10 0000000000000000 0000000000000000
       000000003d4e3830 000000000000000c 000000003d4e3830 000000003d4e38a0
       000000000034aa98 00000000000168a8 000000003d4e3830 000000003d4e3880
Call Trace:
([<000000000001681c>] show_trace+0x138/0x158)
 [<0000000000016902>] show_stack+0xc6/0xf8
 [<00000000000170d4>] dump_stack+0xb0/0xc0
 [<0000000000078810>] print_usage_bug+0x1e8/0x228
 [<000000000007a71c>] mark_lock+0xb14/0xd24
 [<000000000007cd5a>] __lock_acquire+0x792/0xa74
 [<000000000007d0ce>] lock_acquire+0x92/0xb8
 [<0000000000345154>] _spin_lock+0x5c/0x9c
 [<000003e00004c7a2>] tape_open+0x42/0x1a4 [tape]
 [<000003e00005185c>] tapeblock_open+0x98/0xd0 [tape]
Signed-off-by: Frank Munzert <munzert@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>