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Date: Mon, 9 Nov 2020 09:53:40 +0100
From: Christoph Hellwig <hch@lst.de>
To: Hannes Reinecke <hare@suse.de>
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Cc: Justin Sanders <justin@coraid.com>, Mike Snitzer <snitzer@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>, linux-nvme@lists.infradead.org,
	Song Liu <song@kernel.org>, dm-devel@redhat.com,
	Christoph Hellwig <hch@lst.de>, drbd-dev@lists.linbit.com,
	linux-scsi@vger.kernel.org, xen-devel@lists.xenproject.org,
	Ilya Dryomov <idryomov@gmail.com>, Jack Wang <jinpu.wang@cloud.ionos.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Josef Bacik <josef@toxicpanda.com>, nbd@other.debian.org,
	linux-block@vger.kernel.org, Stefan Hajnoczi <stefanha@redhat.com>,
	ceph-devel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
	linux-raid@vger.kernel.org,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Minchan Kim <minchan@kernel.org>, linux-fsdevel@vger.kernel.org,
	Paolo Bonzini <pbonzini@redhat.com>,
	Roger Pau =?iso-8859-1?Q?Monn=E9?= <roger.pau@citrix.com>
Subject: Re: [Drbd-dev] [PATCH 03/24] nvme: let
 set_capacity_revalidate_and_notify update the bdev size
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On Mon, Nov 09, 2020 at 08:53:58AM +0100, Hannes Reinecke wrote:
>> index 376096bfc54a83..4e86c9aafd88a7 100644
>> --- a/drivers/nvme/host/core.c
>> +++ b/drivers/nvme/host/core.c
>> @@ -2053,7 +2053,7 @@ static void nvme_update_disk_info(struct gendisk *disk,
>>   			capacity = 0;
>>   	}
>>   -	set_capacity_revalidate_and_notify(disk, capacity, false);
>> +	set_capacity_revalidate_and_notify(disk, capacity, true);
>>     	nvme_config_discard(disk, ns);
>>   	nvme_config_write_zeroes(disk, ns);
>> @@ -2136,7 +2136,6 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_id_ns *id)
>>   		blk_stack_limits(&ns->head->disk->queue->limits,
>>   				 &ns->queue->limits, 0);
>>   		blk_queue_update_readahead(ns->head->disk->queue);
>> -		nvme_update_bdev_size(ns->head->disk);
>>   		blk_mq_unfreeze_queue(ns->head->disk->queue);
>>   	}
>>   #endif
>
> Hold on.
> This, at the very least, should be a separate patch.
> With this you are changing the behaviour of 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 there 
> is a change on the underlying devices.

Yes, it will.  Take a close look at nvme_update_disk_info and how it is
called.