[libvirt] [PATCH] Add support for disks backed by plain files in LXC

[Daniel P. Berrange]

On Thu, Mar 07, 2013 at 03:55:01PM -0500, John Ferlan wrote:
> On 03/07/2013 06:41 AM, Daniel P. Berrange wrote:
> > From: "Daniel P. Berrange" <berrange at redhat.com>
> > 
> > By using a loopback device, disks backed by plain files can
> > be made available to LXC containers. We make no attempt to
> > auto-detect format if <driver type="raw"/> is not set,
> > instead we unconditionally treat that as meaning raw. This
> > is to avoid the security issues inherant with format
> > auto-detection
> > 
> > Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
> > ---
> >  src/lxc/lxc_controller.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++--
> >  1 file changed, 65 insertions(+), 2 deletions(-)
> > 
> > diff --git a/src/lxc/lxc_controller.c b/src/lxc/lxc_controller.c
> > index a7e715e..176e1be 100644
> > --- a/src/lxc/lxc_controller.c
> > +++ b/src/lxc/lxc_controller.c
> > @@ -356,7 +356,7 @@ static int virLXCControllerValidateConsoles(virLXCControllerPtr ctrl)
> >  }
> >  
> >  
> > -static int virLXCControllerSetupLoopDevice(virDomainFSDefPtr fs)
> > +static int virLXCControllerSetupLoopDeviceFS(virDomainFSDefPtr fs)
> >  {
> >      int lofd;
> >      char *loname = NULL;
> > @@ -377,6 +377,27 @@ static int virLXCControllerSetupLoopDevice(virDomainFSDefPtr fs)
> >  }
> >  
> >  
> > +static int virLXCControllerSetupLoopDeviceDisk(virDomainDiskDefPtr disk)
> > +{
> > +    int lofd;
> > +    char *loname = NULL;
> > +
> > +    if ((lofd = virFileLoopDeviceAssociate(disk->src, &loname)) < 0)
> > +        return -1;
> > +
> > +    /*
> > +     * We now change it into a block device type, so that
> > +     * the rest of container setup 'just works'
> > +     */
> > +    disk->type = VIR_DOMAIN_DISK_TYPE_BLOCK;
> > +    VIR_FREE(disk->src);
> > +    disk->src = loname;
> > +    loname = NULL;
> > +
> > +    return lofd;
> > +}
> > +
> > +
> >  static int virLXCControllerSetupLoopDevices(virLXCControllerPtr ctrl)
> >  {
> >      size_t i;
> > @@ -389,7 +410,7 @@ static int virLXCControllerSetupLoopDevices(virLXCControllerPtr ctrl)
> >          if (fs->type != VIR_DOMAIN_FS_TYPE_FILE)
> >              continue;
> >  
> > -        fd = virLXCControllerSetupLoopDevice(fs);
> > +        fd = virLXCControllerSetupLoopDeviceFS(fs);
> >          if (fd < 0)
> >              goto cleanup;
> >  
> > @@ -402,6 +423,48 @@ static int virLXCControllerSetupLoopDevices(virLXCControllerPtr ctrl)
> >          ctrl->loopDevFds[ctrl->nloopDevs - 1] = fd;
> >      }
> >  
> > +    for (i = 0 ; i < ctrl->def->ndisks ; i++) {
> > +        virDomainDiskDefPtr disk = ctrl->def->disks[i];
> > +        int fd;
> > +
> > +        if (disk->type != VIR_DOMAIN_DISK_TYPE_FILE)
> > +            continue;
> > +
> > +        switch (disk->format) {
> > +            /* We treat 'none' as meaning 'raw' since we
> > +             * don't want to go into the auto-probing
> > +             * business for security reasons
> > +             */
> > +        case VIR_STORAGE_FILE_RAW:
> > +        case VIR_STORAGE_FILE_NONE:
> > +            if (disk->driverName &&
> > +                STRNEQ(disk->driverName, "loop")) {
> > +                virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> > +                               _("disk driver %s is not supported"),
> > +                               disk->driverName);
> > +                goto cleanup;
> > +            }
> > +
> > +            fd = virLXCControllerSetupLoopDeviceDisk(disk);
> > +            if (fd < 0)
> > +                goto cleanup;
> 
> Is there a missing break; here?

Yes, you are right.

Daniel
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