On Fri, Apr 04, 2025 at 08:06:05PM +0800, Ming Lei wrote: > On Fri, Apr 04, 2025 at 11:11:49AM +0200, Christoph Hellwig wrote: > > On Thu, Apr 03, 2025 at 06:54:14PM +0800, Ming Lei wrote: > > > freeze queue should be used for changing block layer generic setting, such > > > as logical block size, PI, ..., and it is enough to quiesce queue for > > > changing loop specific setting. > > > > Why? A queue should generally be frozen for any setting affecting the > > I/O path. Nothing about generic or internal. > > For any driver specific setting, quiesce is enough, because these settings > are only visible in driver IO code path, quiesce does provide the > required protection exactly. What are "internal settings" please? If you change the loop backing file outstanding I/O is relevant. If you change NVMe ANA or retry policies are relevant as they are checked in the I/O completion handler. > > This also misses an explanation of what setting this protects and why > > you think this is safe and the sound fix. > > 1) it is typical queue quiesce use case What is the typical queue quiesce use case? Why is it "typical" and why is it safe. > > 2) loop specific setting is only visible in loop queue_rq() & workfn, and > quiesce does provide the sync for queue_rq() _What_ loop specific setting. > 3) for driver, quiesce is always preferred over freeze, and freeze is > easily mis-used by driver, you know we have bad driver uses for freeze. I am actually much more worried about quiesce. It is much less well defined.
