md/raid1: fix potential data inconsistency issue with write behind device
For write-behind mode, we think write IO is complete once it has reached all the non-writemostly devices. It works fine for single queue devices. But for multiqueue device, if there are lots of IOs come from upper layer, then the write-behind device could issue those IOs to different queues, depends on the each queue's delay, so there is no guarantee that those IOs can arrive in order. To address the issue, we need to check the collision among write behind IOs, we can only continue without collision, otherwise wait for the completion of previous collisioned IO. And WBCollision is introduced for multiqueue device which is worked under write-behind mode. But this patch doesn't handle below cases which could have the data inconsistency issue as well, these cases will be handled in later patches. 1. modify max_write_behind by write backlog node. 2. add or remove array's bitmap dynamically. 3. the change of member disk. Reviewed-by: NNeilBrown <neilb@suse.com> Signed-off-by: NGuoqing Jiang <gqjiang@suse.com> Signed-off-by: NSong Liu <songliubraving@fb.com>
Showing
想要评论请 注册 或 登录