Re: [PATCH v3] nvme: core: shorten duration of multipath namespace rescan

[Christoph Hellwig <hch@lst.de>]

On Tue, Aug 27, 2024 at 05:42:52PM +0200, Martin Wilck wrote:
> Not sure if I understood you correctly, but a single helper for
> unfreezing both the path and the multipath queues won't work.The
> following code block
> 
>         if (blk_queue_is_zoned(ns->queue)) {
>                 ret = blk_revalidate_disk_zones(ns->disk);
>                 if (ret && !nvme_first_scan(ns->disk))
>                         goto out;
>         }
> 
> must be called from nvme_update_ns_info_block() after unfreezing the
> path queue, but its result is used in the code that must run with the
> multipath queue still frozen. So we can freeze both queues at the same
> time, but we must unfreeze them separately.

I don't see what we'd use from blk_revalidate_disk_zones in the
propagation to the multipath node.   I've written up my suggested
prep steps as very lightly tested patches, and they seem to work
fine.  I'll send them out.