On Mon, Sep 27, 2021 at 01:15:54PM +0900, Naohiro Aota wrote:

We need to use direct-IO for zoned devices to preserve the write ordering.
Instead of detecting if the device is zoned or not, we simply use direct-IO
for any kind of device (even if emulated zoned mode on a regular device).

I think this should be ok, we don't want to mix direct io and buffered
writes and both main device opening wrappers do that. As long as it's
abstracted like that we don't need any special detection or flags in the
callers. I was thinking about adding one to open_ctree_flags but that
does not seem necessary.