Re: [dm-devel] [PATCH 1/2] block: fix leaks associated with discard request payload

[Christoph Hellwig <hch lst de>]

On Wed, Jun 30, 2010 at 01:25:01PM +0300, Boaz Harrosh wrote:
> OK, Thanks, I see. Is it one of these operations, (like we have in OSD) where
> the CDB information spills into the payload? like the scatter-gather and extent
> lists and such.

For UNMAP the payload is a list of block number / length pairs, while
the CDB itself doesn't contain any information like that.  It's a rather
awkward command.

> Do we actually use a WRITE_SAME which is not zero? for what use?

The kernel doesn't issue any WRITE SAME without the unmap bit set.