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

[Christoph Hellwig]

On Fri, Jun 16, 2023 at 03:20:38PM +0800, Ming Lei wrote:
> > > GD_DEAD is only set if the device is really dead, then all pending IO
> > > will be failed.
> > 
> > del_gendisk also sets GD_DEAD early on.
> 
> No.
> 
> The hang happens in fsync_bdev() of del_gendisk(), and there are IOs pending on
> bio_queue_enter().

IFF we know we can't do I/O by the time del_gendisk is called, we
need to call mark_disk_dead first and not paper over the problem.

An API that force unfreezes is just broken and will leaves us with
freezecount mismatches.