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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2013-04-26 at 15:42 +0100, George Dunlap wrote:
> On 26/04/13 15:39, Roger Pau Monne wrote:
> > On 26/04/13 16:29, Ian Campbell 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.
> >>
> >> Since the intention of that commit was to allow for 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. It turns out that tap disk can also
> >> potentially handle such paths.
> >>
> >> The only backend which requires a local file/device is PHY but we need to
> >> handle UNKNOWN too in order for subsequent probing to work. Note that it is
> >> not possible to autoprobe the backend if the path is not a local object, 
> >> so we
> >> don't need to worry about autoprobing ceph etc.
> >>
> >> This should probably be revisited to rationalize the probing.
> >>
> >> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Acked-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
> 
> This is a fix, right?  Assuming it is:
> 
> Acked-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>

Applied, thanks.



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