On Thu, May 09, 2019 at 02:34:06PM +0200, Christoph Hellwig wrote: > On Thu, May 09, 2019 at 07:24:12PM +0800, Ming Lei wrote: > > I'd suggest to fix block layer instead of working around the issue here, > > then any driver may benefit from the fix. > > That is my plan, and I started on it. But the fix isn't trivial, and > will probably take a while and be invasive. > > > Especially checking bio->bi_vcnt is just a hack, and drivers should > > never use .bi_vcnt. > > That is why it is explicitly commented as a hack. But a good enough > one to still speed up typical 4K I/Os - one a bio has been cloned > chances are very high we don't care about the fast path any more. NVMe hasn't max segment size limit, so fair enough for typical 4K IO workload: Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx> Thanks, Ming
