Hello, Joseph. On Thu, Feb 08, 2018 at 10:29:43AM +0800, Joseph Qi wrote: > So you mean checking css->refcnt to prevent the further use of > blkg_get? I think it makes sense. Yes. > IMO, we should use css_tryget_online instead, and rightly after taking Not really. An offline css still can have a vast amount of IO to drain and write out. > queue_lock. Because there may be more use of blkg_get in blk_throtl_bio > in the futher. Actually it already has two now. One is in > blk_throtl_assoc_bio, and the other is in throtl_qnode_add_bio. > What do you think of this? As long as we avoid making the bypass paths expensive, whatever makes the code easier to read and maintain would be better. css ref ops are extremely cheap anyway. Thanks. -- tejun
