[libvirt] [PATCH] Add support for guest bind mounts with LXC

[Daniel Veillard]

On Fri, Jun 22, 2012 at 11:29:59AM +0100, Daniel P. Berrange wrote:
> From: "Daniel P. Berrange" <berrange at redhat.com>
> 
> Currently you can configure LXC to bind a host directory to
> a guest directory, but not to bind a guest directory to a
> guest directory. While the guest container init could do
> this itself, allowing it in the libvirt XML means a stricter
> SELinux policy can be written
> ---
>  src/conf/domain_conf.c  |    7 +++++--
>  src/conf/domain_conf.h  |   11 ++++++-----
>  src/lxc/lxc_container.c |    7 +++++++
>  3 files changed, 18 insertions(+), 7 deletions(-)
> 
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index a653fe6..8ce122e 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -263,7 +263,8 @@ VIR_ENUM_IMPL(virDomainFS, VIR_DOMAIN_FS_TYPE_LAST,
>                "block",
>                "file",
>                "template",
> -              "ram")
> +              "ram",
> +              "bind")
>  
>  VIR_ENUM_IMPL(virDomainFSDriverType, VIR_DOMAIN_FS_DRIVER_TYPE_LAST,
>                "default",
> @@ -4260,7 +4261,8 @@ virDomainFSDefParseXML(xmlNodePtr node,
>              if (!source &&
>                  xmlStrEqual(cur->name, BAD_CAST "source")) {
>  
> -                if (def->type == VIR_DOMAIN_FS_TYPE_MOUNT)
> +                if (def->type == VIR_DOMAIN_FS_TYPE_MOUNT ||
> +                    def->type == VIR_DOMAIN_FS_TYPE_BIND)
>                      source = virXMLPropString(cur, "dir");
>                  else if (def->type == VIR_DOMAIN_FS_TYPE_FILE)
>                      source = virXMLPropString(cur, "file");
> @@ -11335,6 +11337,7 @@ virDomainFSDefFormat(virBufferPtr buf,
>  
>      switch (def->type) {
>      case VIR_DOMAIN_FS_TYPE_MOUNT:
> +    case VIR_DOMAIN_FS_TYPE_BIND:
>          virBufferEscapeString(buf, "      <source dir='%s'/>\n",
>                                def->src);
>          break;
> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> index b8d9c87..bdb1f75 100644
> --- a/src/conf/domain_conf.h
> +++ b/src/conf/domain_conf.h
> @@ -656,11 +656,12 @@ struct _virDomainControllerDef {
>  
>  /* Two types of disk backends */
>  enum virDomainFSType {
> -    VIR_DOMAIN_FS_TYPE_MOUNT,   /* Better named 'bind' */
> -    VIR_DOMAIN_FS_TYPE_BLOCK,
> -    VIR_DOMAIN_FS_TYPE_FILE,
> -    VIR_DOMAIN_FS_TYPE_TEMPLATE,
> -    VIR_DOMAIN_FS_TYPE_RAM,
> +    VIR_DOMAIN_FS_TYPE_MOUNT, /* Mounts (binds) a host dir on a guest dir */
> +    VIR_DOMAIN_FS_TYPE_BLOCK, /* Mounts a host block dev on a guest dir */
> +    VIR_DOMAIN_FS_TYPE_FILE,  /* Loopback mounts a host file on a guest dir */
> +    VIR_DOMAIN_FS_TYPE_TEMPLATE, /* Expands a OS template to a guest dir */
> +    VIR_DOMAIN_FS_TYPE_RAM,   /* Mount a RAM filesystem on a guest dir */
> +    VIR_DOMAIN_FS_TYPE_BIND,  /* Binds a guest dir to another guest dir */
>  
>      VIR_DOMAIN_FS_TYPE_LAST
>  };
> diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c
> index b69255e..bf67ba1 100644
> --- a/src/lxc/lxc_container.c
> +++ b/src/lxc/lxc_container.c
> @@ -1025,7 +1025,14 @@ static int lxcContainerMountFS(virDomainFSDefPtr fs,
>          if (lxcContainerMountFSTmpfs(fs) < 0)
>              return -1;
>          break;
> +    case VIR_DOMAIN_FS_TYPE_BIND:
> +        if (lxcContainerMountFSBind(fs, "") < 0)
> +            return -1;
> +        break;
>      case VIR_DOMAIN_FS_TYPE_FILE:
> +        /* We do actually support this, but the lxc controller
> +         * should have associated the file with a loopback
> +         * device and changed this to TYPE_BLOCK for us */
>          lxcError(VIR_ERR_INTERNAL_ERROR,
>                   _("Unexpected filesystem type %s"),
>                   virDomainFSTypeToString(fs->type));

  ACK to the code in the patch but isn't that user visible so ought to
  be somehow documented ?

Daniel

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel at veillard.com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/