On Wed, 15 May 2024, Benjamin Marzinski wrote: > On Tue, May 14, 2024 at 05:04:42PM +0800, Yang Yang wrote: > > Add a list to the struct dm_dev structure to store the associated > > targets, while also allowing differentiation between different target > > types. > > I still think this is more complex than it needs to be. If devices that > support flush_pass_around can guarantee that: > > 1. They will send a flush bio to all of their table devices > 2. They are fine with another target sending the flush bio to their > table devices > > Then I don't see why we need the table devices to keep track of all the > different target types that are using them. Am I missing something here? > > If we don't need to worry about sending a flush bio to a target of each > type that is using a table device, then all we need to do is call > __send_empty_flush_bios() for enough targets to cover all the table > devices. This seems a lot easier to track. We just need another flag in > dm_target, something like sends_pass_around_flush. > > When a target calls dm_get_device(), if it adds a new table device to > t->devices, then it's the first target in this table to use that device. > If flush_pass_around is set for this target, then it also sets > sends_pass_around_flush. In __send_empty_flush() if the table has > flush_pass_around set, when you iterate through the devices, you only > call __send_empty_flush_bios() for the ones with sends_pass_around_flush > set. > > Or am I overlooking something? > > -Ben Yes, I agree that it is complex. I reworked the patch, I'm testing it now and I'll send it when it passes the tests. Mikulas
