On 2020/03/26 18:30, hch@infradead.org wrote:

On Thu, Mar 26, 2020 at 08:23:34AM +0000, Damien Le Moal wrote:

quoted

Open & Close all zones are indeed not super useful, at least on SMR drives. But
finishing all zones does have some benefit, namely the ability to quickly change
all incompletely written zones into "read-only" full zones. For drives with low
zone resources (open or active zones), this can be useful to recover zone
resources. Again, not so much on SMR drives, but this could come in handy for
ZNS drives with low zone resources (max open zones etc).

What quantifies the "some benefit"?  If you have an application that
micro-manages the zone state it better knows what zones are open.  But
even if we want to add a finish all I'd rather wait for ZNS support
to land and real use cases, as it sounds all rather dubious.

OK. Sure, we can delay this until ZNS. The use case are indeed not super clear yet.

In any case, I think that the patch has value as a nice cleanup of the reset vs
reset all request operations (the latter going away). The side effect of it
being that open/close/finish all come for free with it. I would like to get it
in just for this nice cleanup.


-- 
Damien Le Moal
Western Digital Research