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Date:   Wed, 17 Mar 2021 13:47:15 +0000
From:   Christoph Hellwig <hch@infradead.org>
To:     Mikulas Patocka <mpatocka@redhat.com>
Cc:     Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        dm-devel@redhat.com, Zdenek Kabelac <zkabelac@redhat.com>,
        ming.lei@redhat.com
Subject: Re: [PATCH] block: remove the "detected capacity change" message
Message-ID: <20210317134715.GA362913@infradead.org>
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No, it is everything but useless.  It is not needed during device
creation, but that is something that the GENHD_FL_UP check should catch.

You should probably audit the device mapper code why it sets the initial
capacity when the gendisk is up already, as that can cause all kinds of
problems.  If the setting of the initial capacity after add_disk is
indeed intentional you can switch to set_capacity(), but you should
probably document the rationale in a detailed comment.