qemu: block: Add support for VIR_STORAGE_NET_PROTOCOL_NFS

Implement support for the 'nfs' native protocol driver in the qemu
driver.

QEMU accepts numeric UID/GID for 'nfs' protocol file driver thus libvirt
needs to perform the lookup prior to passing it to qemu.

Signed-off-by: Ryan Gahagan <rgahagan@cs.utexas.edu>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>

src/qemu/qemu_block.c

@@ -574,6 +574,29 @@ qemuBlockStorageSourceBuildJSONInetSocketAddress(virStorageNetHostDefPtr host)
 }
 
 
+/**
+ * qemuBlockStorageSourceBuildJSONNFSServer(virStorageNetHostDefPtr host)
+ * @host: the virStorageNetHostDefPtr definition to build
+ *
+ * Formats @hosts into a json object conforming to the 'NFSServer' type
+ * in qemu.
+ *
+ * Returns a virJSONValuePtr for a single server.
+ */
+static virJSONValuePtr
+qemuBlockStorageSourceBuildJSONNFSServer(virStorageNetHostDefPtr host)
+{
+    virJSONValuePtr ret = NULL;
+
+    ignore_value(virJSONValueObjectCreate(&ret,
+                                          "s:host", host->name,
+                                          "s:type", "inet",
+                                          NULL));
+
+    return ret;
+}
+
+
 /**
  * qemuBlockStorageSourceBuildHostsJSONInetSocketAddress:
  * @src: disk storage source
@@ -674,6 +697,39 @@ qemuBlockStorageSourceGetVxHSProps(virStorageSourcePtr src,
 }
 
 
+static virJSONValuePtr
+qemuBlockStorageSourceGetNFSProps(virStorageSourcePtr src)
+{
+    g_autoptr(virJSONValue) server = NULL;
+    virJSONValuePtr ret = NULL;
+
+    if (!(server = qemuBlockStorageSourceBuildJSONNFSServer(&src->hosts[0])))
+        return NULL;
+
+    /* NFS disk specification example:
+     * { driver:"nfs",
+     *   user: "0",
+     *   group: "0",
+     *   path: "/foo/bar/baz",
+     *   server: {type:"tcp", host:"1.2.3.4"}}
+     */
+    if (virJSONValueObjectCreate(&ret,
+                                 "a:server", &server,
+                                 "S:path", src->path, NULL) < 0)
+        return NULL;
+
+    if (src->nfs_uid != -1 &&
+        virJSONValueObjectAdd(ret, "i:user", src->nfs_uid, NULL) < 0)
+        return NULL;
+
+    if (src->nfs_gid != -1 &&
+        virJSONValueObjectAdd(ret, "i:group", src->nfs_gid, NULL) < 0)
+        return NULL;
+
+    return ret;
+}
+
+
 static virJSONValuePtr
 qemuBlockStorageSourceGetCURLProps(virStorageSourcePtr src,
                                    bool onlytarget)
@@ -1181,6 +1237,11 @@ qemuBlockStorageSourceGetBackendProps(virStorageSourcePtr src,
             break;
 
         case VIR_STORAGE_NET_PROTOCOL_NFS:
+            driver = "nfs";
+            if (!(fileprops = qemuBlockStorageSourceGetNFSProps(src)))
+                return NULL;
+            break;
+
         case VIR_STORAGE_NET_PROTOCOL_NONE:
         case VIR_STORAGE_NET_PROTOCOL_LAST:
             virReportEnumRangeError(virStorageNetProtocol, src->protocol);
@@ -2500,11 +2561,16 @@ qemuBlockStorageSourceCreateGetStorageProps(virStorageSourcePtr src,
                 return -1;
             break;
 
+        case VIR_STORAGE_NET_PROTOCOL_NFS:
+            driver = "nfs";
+            if (!(location = qemuBlockStorageSourceGetNFSProps(src)))
+                return -1;
+            break;
+
             /* unsupported/impossible */
         case VIR_STORAGE_NET_PROTOCOL_NBD:
         case VIR_STORAGE_NET_PROTOCOL_ISCSI:
         case VIR_STORAGE_NET_PROTOCOL_VXHS:
-        case VIR_STORAGE_NET_PROTOCOL_NFS:
         case VIR_STORAGE_NET_PROTOCOL_HTTP:
         case VIR_STORAGE_NET_PROTOCOL_HTTPS:
         case VIR_STORAGE_NET_PROTOCOL_FTP:

src/qemu/qemu_domain.c

@@ -4626,6 +4626,37 @@ qemuDomainValidateStorageSource(virStorageSourcePtr src,
         return -1;
     }
 
+    if (actualType == VIR_STORAGE_TYPE_NETWORK &&
+        src->protocol == VIR_STORAGE_NET_PROTOCOL_NFS) {
+        /* NFS protocol may only be used if current QEMU supports blockdev */
+        if (!blockdev) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("'nfs' protocol is not supported with this QEMU binary"));
+            return -1;
+        }
+
+        /* NFS protocol must have exactly one host */
+        if (src->nhosts != 1) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("'nfs' protocol requires the usage of exactly one host"));
+            return -1;
+        }
+
+        /* NFS can only use a TCP protocol */
+        if (src->hosts[0].transport != VIR_STORAGE_NET_HOST_TRANS_TCP) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("'nfs' host must use TCP protocol"));
+            return -1;
+        }
+
+        /* NFS host cannot have a port */
+        if (src->hosts[0].port != 0) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("port cannot be specified in 'nfs' protocol host"));
+            return -1;
+        }
+    }
+
     return 0;
 }
 
@@ -9590,6 +9621,42 @@ qemuProcessPrepareStorageSourceTLSNBD(virStorageSourcePtr src,
 }
 
 
+/* qemuPrepareStorageSourceNFS:
+ * @src: source for a disk
+ *
+ * If src is an NFS source, translate nfs_user and nfs_group
+ * into a uid and gid field. If these strings are empty (ie "")
+ * then provide the hypervisor default uid and gid.
+ */
+static int
+qemuDomainPrepareStorageSourceNFS(virStorageSourcePtr src)
+{
+    if (virStorageSourceGetActualType(src) != VIR_STORAGE_TYPE_NETWORK)
+        return 0;
+
+    if (src->protocol != VIR_STORAGE_NET_PROTOCOL_NFS)
+        return 0;
+
+    if (src->nfs_user) {
+        if (virGetUserID(src->nfs_user, &src->nfs_uid) < 0)
+            return -1;
+    } else {
+        /* -1 indicates default UID */
+        src->nfs_uid = -1;
+    }
+
+    if (src->nfs_group) {
+        if (virGetGroupID(src->nfs_group, &src->nfs_gid) < 0)
+            return -1;
+    } else {
+        /* -1 indicates default GID */
+        src->nfs_gid = -1;
+    }
+
+    return 0;
+}
+
+
 /* qemuProcessPrepareStorageSourceTLS:
  * @source: source for a disk
  * @cfg: driver configuration
@@ -10401,6 +10468,9 @@ qemuDomainPrepareStorageSourceBlockdev(virDomainDiskDefPtr disk,
                                           priv) < 0)
         return -1;
 
+    if (qemuDomainPrepareStorageSourceNFS(src) < 0)
+        return -1;
+
     return 0;
 }