Sweet! I am gonna jump right on studying dm-era today and will get back to you guys with any Q.
tnx so much for you help Joe!
johnu
________________________________________
From: dm-devel-bounces@xxxxxxxxxx [dm-devel-bounces@xxxxxxxxxx] on behalf of Joe Thornber [thornber@xxxxxxxxxx]
Sent: Tuesday, May 06, 2014 6:17 AM
To: device-mapper development
Subject: Re: are there usage examples for dm_sm_metadata_{create|open}?
HI John,
On Sat, May 03, 2014 at 02:24:48AM +0000, John Utz wrote:
> So, the stuff in persistent-data sure seems like a good candidate for getting the job done. :-)
It's nice that you're considering using the pd library. Probably the
simplest user of pd is the dm-era target.
> It seems like the first basic action one would want to perform would
> be to create a metadata 'blob' and then at some point in the future
> one would regularly want to open said metadata blob. The
> dm_sm_metadata_create and open functions seem perfect for the job.
> But for some reason, I am unable to find a place in the md directory
> where this is getting used.
Use dm_tm_create_with_sm(), this creates both the transaction manager,
which you *must* have, and the metadata space map. See the comment at
the end of drivers/md/persistent-data/dm-transaction-manager.h
> I would have thought that dm-cache-metadata.c would be using it, but
it doesnt seem to be thinking about this in the same way. It uses
dm_block_manager_create() and __create_persistent_data_objects().
It does, indirectly.
- Joe
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