Date: Fri, 7 Aug 2015 09:48:39 +0200
From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <tom.leiming@gmail.com>
Cc: Hannes Reinecke <hare@suse.de>, Jens Axboe <axboe@fb.com>,
        Alexander Graf <agraf@suse.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/4] loop: enable different physical blocksizes
Message-ID: <20150807074839.GA17851@lst.de>
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On Fri, Aug 07, 2015 at 03:44:58AM -0400, Ming Lei wrote:
> There shouldn't be any problem about looping over DASP which has
> 4k sector size. Also for debugging purpose, we can easily emulate 4k
> sector size disk by QEMU/virtio-blk.
> 
> We can support 4k sector size on loop for debugging purpose too, but
> the side effect is that some images can't be loop mounted any more
> after its secror size is become larger, then people might complain that.

Have you read the patches?

There isn't any change in default behavior, but it allows you to expose
a non-512 byte sector size _optionally_.  So no images will stop being
loop mountable, quite to the contrary - you can now loop mount an image
copied off from the 4k disk which otherwise would have been unusable
because the file system geometry didn't match what's returned by
the block layer as the sector size.
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