On Sat, Oct 29, 2022 at 04:10:47PM -0700, Bart Van Assche wrote: > On 10/28/22 19:58, Yu Kuai wrote: > > This reverts commit 84f7a9de0602704bbec774a6c7f7c8c4994bee9c. > > > > Because it introduces a problem that rq->__data_len is set to the wrong > > value. > > > > before this patch: > > 1) nr_bytes = rq->__data_len > > 2) rq->__data_len = sdp->sector_size > > 3) scsi_init_io() > > 4) rq->__data_len = nr_bytes > > > > after this patch: > > 1) rq->__data_len = sdp->sector_size > > 2) scsi_init_io() > > 3) rq->__data_len = rq->__data_len -> __data_len is wrong > > > > It will cause that io can only complete one segment each time, and the io > > will requeue in scsi_io_completion_action(), which will cause severe > > performance degradation. > > It's probably worth mentioning that the code affected by this patch has been > removed from the master branch and hence that this patch is only needed for > stable kernels. Anyway: Yes, that needs to be in the changelog in lots of detail. Yu, please fix this up and resend. thanks, greg k-h
