Re: 2.6.32-rc5: surprise removal of USB mass storage, and whole system goes to hell

[Heinz Diehl <htd@fancy-poultry.org>]

On 29.10.2009, Jens Axboe wrote: 

I had the same problem which has been discussed in this thread, 
and can confirm that this patch from Jens Axboe (which is already merged into 2.6.32-rc7) 
fixes it for me.

> diff --git a/mm/backing-dev.c b/mm/backing-dev.c
> index 4f53a6d..756c31b 100644
> --- a/mm/backing-dev.c
> +++ b/mm/backing-dev.c
> @@ -614,6 +616,18 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
>  		kthread_stop(wb->task);
>  }
>  
> +static void bdi_prune_sb(struct backing_dev_info *bdi)
> +{
> +	struct super_block *sb;
> +
> +	spin_lock(&sb_lock);
> +	list_for_each_entry(sb, &super_blocks, s_list) {
> +		if (sb->s_bdi == bdi)
> +			sb->s_bdi = NULL;
> +	}
> +	spin_unlock(&sb_lock);
> +}
> +
>  void bdi_unregister(struct backing_dev_info *bdi)
>  {
>  	if (bdi->dev) {
> @@ -624,6 +638,8 @@ void bdi_unregister(struct backing_dev_info *bdi)
>  		device_unregister(bdi->dev);
>  		bdi->dev = NULL;
>  	}
> +
> +	bdi_prune_sb(bdi);
>  }
>  EXPORT_SYMBOL(bdi_unregister);