Re: [Xen-devel] [PATCH 0 of 4] aio event fd support to blktap2

["David P. Quigley" <dpquigl@xxxxxxxxxxxxx>]

On Tue, 2010-02-02 at 15:10 -0800, Daniel Stodden wrote:
> On Tue, 2010-02-02 at 17:53 -0500, David P. Quigley wrote:
> > Is this patch set related to the AIO poll support that blocktap2 keeps
> > complaining about when I use tap:tapdisk:aio as the disk type? 
> 
> On pvops, yes.
> 
> > I found
> > the code that changes io_setup in the Novell Xen patches but its part of
> > a reasonably large patch.
> 
> Shouldn't depend on the disktype. As long as it's blktap, not blkback on
> a raw vdi, all disk drivers depend on this.
> 
> The io_setup change you're referring might rather be the old way of
> doing things. It made io_setup return an fd to poll, if the io_setup
> caller calls with a 'magic' (1, actually) aio_ctx value.
> 
> Daniel
> 
I believe that is the case. The error message below is what I'm getting
from tapdisk2. The ioctl successfully completes and the devices are
created. However it just can't grab the fd to use so it then uses a
second ioctl to remove the device shortly after.

Dave

Feb  1 17:29:20 localhost tapdisk2[2798]: Created /dev/xen/blktap-2/control 
device
Feb  1 17:29:20 localhost tapdisk2[2798]: Created /dev/xen/blktap-2/blktap0 
device
Feb  1 17:29:20 localhost tapdisk2[2798]: Created /dev/xen/blktap-2/tapdev0 
device
Feb  1 17:29:20 localhost tapdisk2[2798]: new interface: ring: 251, device: 
253, minor: 0
Feb  1 17:29:20 localhost tapdisk2[2798]: Couldn't get fd for AIO poll support. 
 This is probably because your kernel does not have the aio-poll patch applied.




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