Re: [PATCH v5] block: Remove queue freezing from several sysfs store callbacks

[Ming Lei <ming.lei@redhat.com>]

On Mon, Nov 10, 2025 at 08:24:18AM -0800, Bart Van Assche wrote:
> Freezing the request queue from inside sysfs store callbacks may cause a
> deadlock in combination with the dm-multipath driver and the
> queue_if_no_path option. Additionally, freezing the request queue slows
> down system boot on systems where sysfs attributes are set synchronously.
> 
> Fix this by removing the blk_mq_freeze_queue() / blk_mq_unfreeze_queue()
> calls from the store callbacks that do not strictly need these callbacks.
> This patch may cause a small delay in applying the new settings.
> 
> This patch affects the following sysfs attributes:
> * io_poll_delay
> * io_timeout
> * nomerges
> * read_ahead_kb
> * rq_affinity

I'd suggest to add words why freeze isn't needed, such as:

```
Intermediate value isn't possible, and either the old or new value is just fine to take
in io fast path.
```

otherwise this patch is good for me.


Thanks, 
Ming