EXPORT_SYMBOL_GPL - ok. #ifdef CONFIG_BLK_FILTER or IS_ENABLED() - It's a matter of habit. > double blank line Ok, I did. Looks like a candidate for ./scripts/checkpatch.pl. > Separate into multiple patches: one that introduces the filter > functions/ops code and another that changes the block layer where needed. I'll think about it. Personally, it seems to me that this separation does not make it easier to understand the code. It is important for me to know immediately where the function is called, and this determines its behavior. -- Sergei Shtepa Veeam Software developer.