Re: [Xen-devel] qemu xen_disk mis-accounting?

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 10 May 2012, Jan Beulich wrote:
> ioreq_release() gets called from two places, yet only in the
> blk_send_response_all() case does it appear appropriate to decrement
> blkdev->requests_finished. In the error handling path of
> blk_handle_requests() I would think it should decrement
> blkdev->requests_inflight instead.
>
> While blkdev->requests_finished isn't being used anywhere,
> blkdev->requests_inflight serves blk_handle_requests() to tell
> whether to call qemu_bh_schedule(), so this isn't a purely cosmetic
> mistake afaics (and the error path in question is actually being
> consistently exercised by our frontends probing for the packet
> command extension - yes, it should have been implemented via
> xenstore node presence, but the author failed to do so back then).

The error handling path of blk_handle_requests() should definitely
decrement blkdev->requests_inflight for the reasons you mentioned, but
it should also call ioreq_release(), because otherwise
blk_send_response_all could call blk_send_response_one on the ioreq that
wasn't parsed correctly.

Could you please submit a patch to add blkdev->requests_inflight-- in
the right place?

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