[OpenIndiana-discuss] access to partition table inside zvol

[Andrew Gabriel]

Evgenii Lepikhin wrote:
> 2011/12/23 Evgenii Lepikhin <johnlepikhin at gmail.com>:
>
>   
>>> Looping back through iSCSI is the way.
>>>       
>> But it's a bit complicated. No other way?
>>     
>
> I have patched lofi subsystem to support offsets. If somebody
> interested, patch is attached.
>   

There's been a long standing RFE outstanding for lofi to become aware of 
disk labeling, so it can give device access to individual FDISK 
partitions and slices (SunOS or GPT/EFI). Now that the driver disk 
labeling code has been commoned up 
(http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/common/io/cmlb.c), 
this should be significantly easier to do than it was originally when 
this code was sprinkled all over the various target drivers. I talked 
about this at a LOSUG meeting probably a couple of years ago when 
someone asked a question about doing something similar to what you want 
to do. Proper label support would enable you do to access your EFI/GPT 
slices using device nodes possibly something like:
/dev/lofi/1.d/s0, /dev/lofi/1.d/s1, etc

IIRC, the suggestion which was floated at the LOSUG discussion for a 
labeled loopback block device was to have something like:
/dev/lofi/1 -> 1.d/p0
/dev/lofi/1.d/p0
/dev/lofi/1.d/p1
/dev/lofi/1.d/p2
/dev/lofi/1.d/p3
/dev/lofi/1.d/p4
/dev/lofi/1.d/s0
/dev/lofi/1.d/s1
/dev/lofi/1.d/s2
/dev/lofi/1.d/s3
...etc
and likewise for /dev/rlofi/...

Offset support in lofi might be a good idea too for other reasons, but 
in my view, something more automatic like the above should be used to 
handle the more common cases of partitions/slices.

-- 
Andrew Gabriel