storage: add ploop volume type

Ploop image consists of directory with two files: ploop image itself,
called root.hds and DiskDescriptor.xml that contains information about
ploop device: https://openvz.org/Ploop/format.
Such volume are difficult to manipulate in terms of existing volume types
because they are neither a single files nor a directory.
This patch introduces new volume type - ploop. This volume type is used
by ploop volume's exclusively.
Signed-off-by: NOlga Krishtal <okrishtal@virtuozzo.com>
Signed-off-by: NJán Tomko <jtomko@redhat.com>

docs/formatstorage.html.in

@@ -494,7 +494,7 @@
       A storage volume will generally be either a file or a device
       node; <span class="since">since 1.2.0</span>, an optional
       output-only attribute <code>type</code> lists the actual type
-      (file, block, dir, network, or netdir), which is also available
+      (file, block, dir, network, netdir or ploop), which is also available
       from <code>virStorageVolGetInfo()</code>.  The storage volume
       XML format is available <span class="since">since 0.4.1</span>
     </p>

include/libvirt/libvirt-storage.h

@@ -122,6 +122,7 @@ typedef enum {
     VIR_STORAGE_VOL_NETWORK = 3,  /* Network volumes like RBD (RADOS Block Device) */
     VIR_STORAGE_VOL_NETDIR = 4,   /* Network accessible directory that can
                                    * contain other network volumes */
+    VIR_STORAGE_VOL_PLOOP = 5,    /* Ploop based volumes */
 
 # ifdef VIR_ENUM_SENTINELS
     VIR_STORAGE_VOL_LAST

src/conf/storage_conf.c

@@ -52,7 +52,8 @@ VIR_LOG_INIT("conf.storage_conf");
 
 VIR_ENUM_IMPL(virStorageVol,
               VIR_STORAGE_VOL_LAST,
-              "file", "block", "dir", "network", "netdir")
+              "file", "block", "dir", "network",
+              "netdir", "ploop")
 
 VIR_ENUM_IMPL(virStoragePool,
               VIR_STORAGE_POOL_LAST,

src/storage/storage_backend_fs.c

@@ -1085,6 +1085,8 @@ virStorageBackendFileSystemVolCreate(virConnectPtr conn ATTRIBUTE_UNUSED,
 
     if (vol->target.format == VIR_STORAGE_FILE_DIR)
         vol->type = VIR_STORAGE_VOL_DIR;
+    else if (vol->target.format == VIR_STORAGE_FILE_PLOOP)
+        vol->type = VIR_STORAGE_VOL_PLOOP;
     else
         vol->type = VIR_STORAGE_VOL_FILE;
 
@@ -1259,6 +1261,7 @@ virStorageBackendFileSystemVolDelete(virConnectPtr conn ATTRIBUTE_UNUSED,
             }
         }
         break;
+    case VIR_STORAGE_VOL_PLOOP:
     case VIR_STORAGE_VOL_BLOCK:
     case VIR_STORAGE_VOL_NETWORK:
     case VIR_STORAGE_VOL_NETDIR:

tools/virsh-volume.c

@@ -965,7 +965,8 @@ VIR_ENUM_IMPL(virshStorageVol,
               N_("block"),
               N_("dir"),
               N_("network"),
-              N_("netdir"))
+              N_("netdir"),
+              N_("ploop"))
 
 static const char *
 virshVolumeTypeToString(int type)