Re: [PATCH v3] fs: Invalidate the cache for a parent block-deviceif fsync() is called for a partition

From: Andrew Morton
Date: Tue Jan 31 2012 - 14:48:26 EST


On Tue, 31 Jan 2012 14:37:48 -0500
Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:

> 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.

This can be done via an offsetting driver.

> 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,

why? I don't see the problem - supporting /dev/sdaX should be
straightforward. /dev/sda rarely gets used and would need a bit of
special-case handling.

Please provide all the details as you see them and stop making me email
more questions to you.

> at which point
> blkdev_get_block in either form will simply go away.
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