RE: status of block-integrity

From: berthiaume, wayne
Date: Tue Dec 31 2013 - 15:06:49 EST


You can add there are SCSI targets out there employing this feature as well. =;^)

-----Original Message-----
From: linux-scsi-owner@xxxxxxxxxxxxxxx [mailto:linux-scsi-owner@xxxxxxxxxxxxxxx] On Behalf Of Martin K. Petersen
Sent: Monday, December 23, 2013 8:35 AM
To: Christoph Hellwig
Cc: Jens Axboe; linux-kernel@xxxxxxxxxxxxxxx; linux-scsi@xxxxxxxxxxxxxxx
Subject: Re: status of block-integrity

>>>>> "Christoph" == Christoph Hellwig <hch@xxxxxxxxxxxxx> writes:

Christoph> We have the block integrity code to support DIF/DIX in the
Christoph> the tree for about 5 and a half years, and we still don't
Christoph> have a single consumer of it.

What do you mean? If you have a DIX-capable HBA (lpfc, qla2xxx, zfcp) then integrity protection is active from the block layer down. The only code that's not currently being exercised are the tag interleaving functions. I was hoping the FS people would use them for back pointers but nobody seemed to bite.


Christoph> Given that we'll have a lot of work to do in this area with
Christoph> block multiqueue I think it's time to either kill it off for
Christoph> good or make sure we can actually use and test it.

I don't understand why multiqueue would require a lot of work? It's just an extra scatterlist per request.

And obviously, if there's anything that needs to be done in this area I'll be happy to do so...

--
Martin K. Petersen Oracle Linux Engineering

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