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Lars Ellenberg authored
This fixes ASSERT( mdev->state.disk == D_FAILED ) in drivers/block/drbd/drbd_main.c When we detach from local disk, we let the local refcount hit zero twice. First, we transition to D_FAILED, so we won't give out new references to incoming requests; we still may give out *internal* references, though. Once the refcount hits zero [1] while in D_FAILED, we queue a transition to D_DISKLESS to our worker. We need to queue it, because we may be in atomic context when putting the reference. Once the transition to D_DISKLESS actually happened [2] from worker context, we don't give out new internal references either. Between hitting zero the first time [1] and actually transition to D_DISKLESS [2], there may be a few very short lived internal get/put, so we may hit zero more than once while being in D_FAILED, or even see a race where a an internal get_ldev() happened while D_FAILED, but the corresponding put_ldev() happens just after the transition to D_DISKLESS. That's why we have the additional test_and_set_bit(GO_DISKLESS,); and that's why the assert was placed wrong. Since there was exactly one code path left to drbd_go_diskless(), and that checks already for D_FAILED, drop that assert, and fold in the drbd_queue_work(). Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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