[dm-devel] [PATCH V3] blk-mq: introduce BLK_STS_DEV_RESOURCE

[Ming Lei]

On Tue, Jan 30, 2018 at 03:37:38AM +0000, Bart Van Assche wrote:
> On Tue, 2018-01-30 at 11:31 +0800, Ming Lei wrote:
> > Please take a look at drivers, when BLK_STS_RESOURCE is returned, who
> > will call blk_mq_delay_run_hw_queue() for drivers?
> 
> As you know the SCSI and dm drivers in kernel v4.15 already call that function
> whenever necessary.

We have concluded that it is generic issue which need generic solution[1].

[1] https://marc.info/?l=linux-kernel&m=151638176727612&w=2

[ming at ming linux]$ git grep -n BLK_STS_RESOURCE ./drivers/ | wc -l
43

Almost every driver need this kind of change if BLK_STS_RESOURCE is returned
from IO path. And the failure can be caused by kmalloc(GFP_ATOMIC), DMA Mapping,
or what ever.

Thanks,
Ming