Re: [Xen-devel] [PATCH] libxl: stat the path for all non-qdisk backends (including unknown)

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2013-05-10 at 14:46 +0100, George Dunlap wrote:
> On Fri, Apr 26, 2013 at 3:29 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> > On Fri, 2013-04-26 at 15:17 +0100, Sylvain Munaut wrote:
> >> > Since the intention of that commit was to allow for qdisk backends with 
> >> > no
> >> > explicit file in dom0 (i.e. network remote backend such as ceph) the 
> >> > lowest
> >> > impact fix appears to be to make that explicit. This should probably be
> >> > revisited to rationalize the probing.
> >>
> >> What about the remote disk case of blktap ?  blktap2.5 supports NBD
> >> already AFAIK
> >> and I'm pretty sure I'll hit that same stat issue soon for another
> >> remote blktap case.
> >
> > Right, sounds like I should have gone with my first instinct which was:
> >
> > 8<------------------------------------------------------------
> >
> > From 884beff4a897d785f61705dcfa2f048536982d7c Mon Sep 17 00:00:00 2001
> > From: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Date: Fri, 26 Apr 2013 12:41:43 +0100
> > Subject: [PATCH] libxl: stat the path for all non-qdisk backends (including 
> > unknown)
> >
> > The commit a8a1f236a296 "libxl: Only call stat() when adding a disk if we
> > expect a device to exist." changed things to only stat the file when the phy
> > backend was explicitly requested. This broke the case where we are probing 
> > and
> > would normally be able to decide on the phy option.
> 
> So at the moment qdisk backends aren't checked at all with this --
> which means that if you give a path to a file that doesn't exist via,
> for example, xl cd-insert, things fail in weird ways:
> 
> 1. In qemu-traditional, the command silently completes; the effect is
> that the disk currently in the drive is ejected
> 
> 2. in qemu-upstream, qmp returns an error which is reported.  The disk
> is ejected from the guest, but the xenstore entries are not updated
> (still contain the old values)
> 
> It seems like we should probably also at least check if disk_format is RAW.

A kit if these issues will come back with disk driver domains I think.

> OTOH, I don't seen an option for disk_format to be ceph; is it just
> listed as "raw" as well?  That doesn't seem right...

That might well be the correct answer, but not for 4.3 I suspect?

Ian.


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel