[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH 03/24] nvme: let set_capacity_revalidate_and_notify update the bdev size
On 11/10/20 12:28 AM, Sagi Grimberg wrote: But that's precisely my point; there won't be an AEN for _all_ paths, but rather one AEN per path. Which will be processed separately, leading to the issue described above.[ .. ]Okay, then: What would be the correct way of handling a size update for NVMe multipath?Originally nvme multipath would update/change the size of the multipath device according to the underlying path devices.With this patch the size of the multipath device will _not_ change if thereis a change on the underlying devices.Yes, it will. Take a close look at nvme_update_disk_info and how it is called.Assuming we're getting an AEN for each path signalling the size change (or a controller reset leading to a size change).So if we're updating the size of the multipath device together with the path device at the first AEN/reset we'll end up with the other paths having a different size than the multipath device (and the path we've just been updating).- Do we care, or cross fingers and hope for the best?- Shouldn't we detect the case where we won't get a size update for the other paths, or, indeed, we have a genuine device size mismatch due to a misconfiguration on the target?IE shouldn't we have a flag 'size update pending' for the other paths,, to take them out ouf use temporarily until the other AENs/resets have been processed?the mpath device will take the minimum size from all the paths, that is what blk_stack_limits does. When the AEN for all the paths will arrive the mpath size will update. Not sure how this is different than what we have today... Oh, that is a problem even today. So we should probably move it to a different thread... Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@xxxxxxx +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
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