[Libguestfs] guestmount failing to mount a qcow image

[Richard W.M. Jones]

On Fri, Dec 09, 2011 at 12:08:06AM +0000, Pádraig Brady wrote:
> On 12/08/2011 05:43 PM, Richard W.M. Jones wrote:
> > On Thu, Dec 08, 2011 at 04:49:08PM +0000, Pádraig Brady wrote:
> >> # guestmount --rw -a /tmp/disk -i /tmp/tmplFlBCc
> >> libguestfs: error: mount_options: mount_options_stub: /dev/root: No
> >> such file or directory
> > 
> > This image works OK with libguestfs 1.14/1.15.  I suspect the commit
> > you need to make it work is:
> > 
> >   commit 917f947590c92318fee2545ba88245d0de012e31
> >   Author: Richard W.M. Jones <rjones at redhat.com>
> >   Date:   Fri Sep 16 15:26:20 2011 +0100
> > 
> >     inspection: Handle /dev/root in /etc/fstab.
> >     
> >     This means "the device that holds /etc/fstab", so map it correctly.
> >     
> >     This fixes support for ttylinux and also some other guests that use
> >     /dev/root instead of a real device name.
> > 
> > The bigger issue here for OpenStack is how to recover gracefully when
> > inspection fails.  Even though guestmount -i doesn't work on the older
> > libguestfs, you could still have used explicit -m option(s).
> 
> Yep that works:  `guestmount -a annoying.qcow2 -m /dev/sda mount_dir/`
> 
> The awkward thing about the failure mode is that it warns,
> but returns EXIT_SUCCESS, leaving the dir "half mounted"
> (and then fusermount -u gives an EBUSY error (hmm I might use -z))
> I'm tempted to assume an error if there is any output to stderr.

Please file a bug about this:
http://libguestfs.org/ -> Bug reports -> Enter a new bug report

> > You would have to know somehow which filesystem(s) are available and which
> > you want to modify.  That is information you can get from the API
> > (g.list_filesystems) or using virt-filesystems.  It's reasonable, if
> > there is only one filesystem in the image, to just mount that one.
> > What's less clear is what should happen if there are multiple
> > filesystems: that information would have to be passed down from the
> > user through OpenStack.
> 
> There is a 'partition' variable passed through the api,
> I guess it could be 0 = /dev/sda, 1..N = /dev/sdaN, -1 => -i
> 
> I'll sort something out.

Yes, I saw that, but I don't think it is enough.  For one thing most
*nix-like OSes have multiple filesystems, and guestmount lets you
specify multiple -m options.

Rich.

-- 
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