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

[Mike Snitzer <snitzer redhat com>]

On Sun, Jun 27 2010 at  8:32am -0400,
FUJITA Tomonori <fujita tomonori lab ntt co jp> wrote:

> On Sun, 27 Jun 2010 13:07:12 +0200
> Christoph Hellwig <hch lst de> wrote:
> 
> > > How about this?
> > 
> > As I tried to explain before this utterly confuses the I/O completion
> > path.  With the patch applied even a simple mkfs.xfs that issues discard
> > just hangs.
> 
> Wired. I just tried mkfs.xfs against scsi_debug with my block patches
> (I saw one discard command). Seemed that it worked fine.

My leak fixes have been tested extensively against all permuations of
devices with discards (ATA trim, SCSI UNMAP, SCSI WRTIE SAME w/ unmap=1).

I think we need to get Christoph's discard payload transformation
complete by fixing the leaks _without_ trying to rework how discard
commands are tagged, etc.  E.g. fix what Jens already has staged in
linux-2.6-block's 'for-next' and 'for-2.6.36'.

With that sorted out we can then look at longer term changes to cleanup
discard request processing.

Regards,
Mike