[PATCH 1/4] blk-mq: add API of blk_mq_unfreeze_queue_force

[Ming Lei]

On Thu, Jun 15, 2023 at 09:16:27AM -0600, Keith Busch wrote:
> On Thu, Jun 15, 2023 at 10:32:33PM +0800, Ming Lei wrote:
> > NVMe calls freeze/unfreeze in different contexts, and controller removal
> > may break in-progress error recovery, then leave queues in frozen state.
> > So cause IO hang in del_gendisk() because pending writeback IOs are
> > still waited in bio_queue_enter().
> 
> Shouldn't those writebacks be unblocked by the existing check in
> bio_queue_enter, test_bit(GD_DEAD, &disk->state))? Or are we missing a
> disk state update or wakeup on this condition?

GD_DEAD is only set if the device is really dead, then all pending IO
will be failed.

We need to try to handle these IOs first if device isn't set as dead by
calling blk_mark_disk_dead().

Thanks,
Ming