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    SubjectRe: [PATCH 1/2] cdrom: always check_disk_change() on open
    On (Tue) 10 May 2011 [09:44:28], Jens Axboe wrote:
    > On 2011-05-10 08:42, Amit Shah wrote:
    > > On (Fri) 29 Apr 2011 [10:15:50], Jens Axboe wrote:
    > >> On 2011-04-29 08:57, Amit Shah wrote:
    > >>> On (Wed) 06 Apr 2011 [05:20:09], Tejun Heo wrote:
    > >>>> 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.
    > >>>>
    > >>>> Signed-off-by: Tejun Heo <tj@kernel.org>
    > >>>> Reported-by: Amit Shah <amit.shah@redhat.com>
    > >>>> Tested-by: Amit Shah <amit.shah@redhat.com>
    > >>>
    > >>> Ping?
    > >>>
    > >>> Also, please mark this for stable-2.6.38.
    > >>
    > >> Done, added for 2.6.39 and marked stable for 2.6.38.
    > >
    > > Ping again. Don't see this yet in Linus's git tree.
    >
    > It was added for 2.6.40 and marked for stable.

    OK, Thanks.

    Amit


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