On 07/21/2014 01:29 PM, Christoph Hellwig wrote:
On Mon, Jul 21, 2014 at 10:27:21AM +0200, Hannes Reinecke wrote:
ZBC drives are close to disk devices, so update sd.c to handle
ZBC drives correctly.
While the other patches all look fine with me I strongly disagree with
this one. Devices reporting the ZBC device type must have sequential
required zones, so they are _not_ anywhere close to disk devices,
and writes to them will cause errors that we aren't evenable able to
handle yet.
If it makes some sort of experiment easier for you we can add a way to
force ZBC devices to use sd.c conditionally. Do you have a test device
that this works with?
Yes, I have.
I was actually considering implementing a module option for sd
(eg attach_zbc) to allow zac/zbc devices to be attached to the sd
driver.
Which will be off per default, so your concern should be addressed.
However, zbc devices _are_ similar to normal 'sd' devices; it's only
that some commands might fail unexpectedly.
But all the usual commands from sbc are supported, so I found it a
bit odd having to implement my own device driver (which would be a
clone of 'sd' anyway).
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@xxxxxxx +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
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