Re: [Qemu-devel] [PATCH 12/16] scsi-generic: use plain ioctl

[adq <adq@lidskialf.net>]

On 20 November 2010 08:23, Nicholas A. Bellinger <nab@linux-iscsi.org> wrote:
> On Sat, 2010-11-20 at 01:25 +0000, adq wrote:
>> On 20 November 2010 00:41, Nicholas A. Bellinger <nab@linux-iscsi.org> wrote:
>> > On Fri, 2010-11-19 at 19:39 +0100, Christoph Hellwig wrote:
>> >> On Thu, Nov 18, 2010 at 03:47:36PM +0100, Hannes Reinecke wrote:
>> >> >
>> >> > aio_ioctl is emulated anyway and currently broken.
>> >>
>> >> What's broken about it currently?
>> >
>> > Mmmmmm, I do not recall this being broken in the first place..?  There
>> > was a single issue with megasas+bdrv_aio_ioctl() with WinXP (that did
>> > not appear with lsi53c895a) that was mentioned on the list earlier in
>> > the year that required a patch to use bdev_ioctl(), but last I recall
>> > Hannes had already fixed this in recent megasas.c code w/ 32-bit MSFT
>> > guests.  Also, this is what I have been with scsi_generic.c and
>> > scsi_bsg.c into TCM_loop in my v0.12.5 megasas tree, and I am not
>> > observing any obvious issues with AIO IOCTLs for SG_IO/BSG into Linux
>> > guests.
>> >
>> > I will give AIO IOCTL ops a run with these on v2.6.37-rc2 lock-less KVM
>> > host mode <-> TCM_Loop to verify against the v0.12.5 megasas tree.
>>
>> Could this AIO ioctl breakage perhaps be the one I fixed here?
>> http://web.archiveorange.com/archive/v/1XS1vROmfC7dN9wYxsmt
>>
>> The patch is defintely in the latest git... it works fine for me with
>> my scsi-generic MMC command patches.
>>
>
> Interesting read, and thanks for the heads up on this bit..   I do not
> personally recall running into any issues with TYPE_DISK w/ lsi53c895a
> and AIO SG_IO into WinXP guests on v0.12.5 code.   After a quick double
> check in the v0.12.5 megasas tree, the proper get_async_context_id() is
> still present:
>
> http://git.kernel.org/?p=virt/kvm/nab/qemu-kvm.git;a=blob;f=posix-aio-compat.c;h=ccdbf9a16d0ef1d7e57c87dbe43f318d4c7a5967;hb=HEAD#l560
>
> So it appears this acb->async_context_id was incorrectly dropped during
> v0.13 development, and with your fix commited into v0.13 mainline code
> that Hannes should be able to safetly drop this the megasas series,
> yes..?
>
> Thank you for your comments!

No problem. Oh, that bug was /definitely/ in the released 0.12.x
series code; I spotted it when trying to get scsi-generic to work on
arch linux, which was using 0.12.x.