[Devel] [PATCH] blk-cbt: Enable interrupts when unlocking in blk_cbt_update_size

[Pavel Tikhomirov]

On 01.02.2023 21:22, Nikolay Borisov wrote:
> blk_cbt_update_size uses spin_lock_irq to lock the cbt while pages are
> being copied and the new cbt is published at q->cbt. This lock is used
> to synchronize against blk_cbt_release, which can be called within
> softirq context. This function requires unlocking be done with
> spin_unlock_irq so that interrupts are properly reenabled. Without
> this fix the core on which blk_cbt_update_size run would end up with
> interrupts being disabled.
> 

Reviewed-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
Fixes: e69ca16f4135 ("cbt: introduce changed block tracking")

> Reported-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
> Signed-off-by: Nikolay Borisov <nikolay.borisov at virtuozzo.com>
> ---
>   block/blk-cbt.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/block/blk-cbt.c b/block/blk-cbt.c
> index 32485c793484..083ed5785031 100644
> --- a/block/blk-cbt.c
> +++ b/block/blk-cbt.c
> @@ -607,7 +607,7 @@ void blk_cbt_update_size(struct block_device *bdev)
>   	}
>   	rcu_assign_pointer(q->cbt, new);
>   	in_use = cbt->count;
> -	spin_unlock(&cbt->lock);
> +	spin_unlock_irq(&cbt->lock);
>   	if (!in_use)
>   		call_rcu(&cbt->rcu, &cbt_release_callback);
>   err_mtx:

-- 
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.