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Date: Tue, 31 Jan 2012 14:37:48 -0500
From: Christoph Hellwig <hch@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>, Niels de Vos <ndevos@redhat.com>,
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        Mikulas Patocka <mpatocka@redhat.com>, Jeff Moyer <jmoyer@redhat.com>,
        "Bryn M. Reeves" <bmr@redhat.com>
Subject: Re: [PATCH v3] fs: Invalidate the cache for a parent block-device if
 fsync() is called for a partition
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On Tue, Jan 31, 2012 at 11:32:50AM -0800, Andrew Morton wrote:
> I didn't say the kernel would support this as-is.
> 
> If the partitioning scheme requires writing to the individual
> partitions then something would need to be done, such as a simple
> offsetting DM driver.

Writing partition tables requires writing to them main block device.

Seriously - if people want to support block devices nodes > 16TB dealing
with this isn't the problem.  They'll need to find a way to do buffered
I/O without using the pagecache to get it right, at which point
blkdev_get_block in either form will simply go away.