cdrom_open() called check_disk_change() after the rest of open path
succeeded which leads to the following bizarre behavior.
* After media change, if the device opened without O_NONBLOCK,
open_for_data() naturally fails with -ENOMEDIA and
check_disk_change() is never called. The media is known to be gone
and the open failure makes it obvious to the userland but device
invalidation never happens.
* But if the device is opened with O_NONBLOCK, all the checks are
bypassed and cdrom_open() doesn't notice that the media is not there
and check_disk_change() is called and invalidation happens.
There's nothing to be gained by avoiding calling check_disk_change()
on open failure. Common cases end up calling check_disk_change()
anyway. All we get is inconsistent behavior.
Fix it by moving check_disk_change() invocation to the top of
cdrom_open() so that it always gets called regardless of how the rest
of open proceeds.
Stable: 2.6.38
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Amit Shah <amit.shah@redhat.com>
Tested-by: Amit Shah <amit.shah@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Tejun Heo