On Sun, Feb 26, 2017 at 2:23 AM, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > On Fri, Feb 24, 2017 at 11:42:39PM +0800, Ming Lei wrote: >> MD need this helper to remove the last added page, so introduce >> it. > > If MD really has a valid use case for this it should open code the > operation. The semantics look deeply fishy to me. Thinking about MD's case further, and looks bio_add_page() won't fail at all in case that queue's limit isn't applied in bio_add_page() in future. So I will change MD's handling in this case and avoid to introduce bio_remove_last_page() in V2. Thanks, Ming Lei