storage: gluster: Support multiple hosts in backend functions

As gluster natively supports multiple hosts for failover reasons we can
easily add the support to the storage driver code in libvirt.

Extract the code setting an individual host into a separate function and
call them in a loop. The new code also tries to keep the debug log
entries sane.

src/storage/storage_backend_gluster.c

@@ -570,25 +570,55 @@ virStorageFileBackendGlusterDeinit(virStorageSourcePtr src)
 }
 
 static int
-virStorageFileBackendGlusterInit(virStorageSourcePtr src)
+virStorageFileBackendGlusterInitServer(virStorageFileBackendGlusterPrivPtr priv,
+                                       virStorageNetHostDefPtr host)
 {
-    virStorageFileBackendGlusterPrivPtr priv = NULL;
-    virStorageNetHostDefPtr host = &(src->hosts[0]);
-    const char *hostname;
+    const char *transport = virStorageNetHostTransportTypeToString(host->transport);
+    const char *hoststr = NULL;
     int port = 0;
 
-    if (src->nhosts != 1) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                       _("Expected exactly 1 host for the gluster volume"));
+    switch ((virStorageNetHostTransport) host->transport) {
+    case VIR_STORAGE_NET_HOST_TRANS_RDMA:
+    case VIR_STORAGE_NET_HOST_TRANS_TCP:
+        hoststr = host->name;
+
+        if (host->port &&
+            virStrToLong_i(host->port, NULL, 10, &port) < 0) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("failed to parse port number '%s'"),
+                           host->port);
+            return -1;
+        }
+
+        break;
+
+    case VIR_STORAGE_NET_HOST_TRANS_UNIX:
+        hoststr = host->socket;
+        break;
+
+    case VIR_STORAGE_NET_HOST_TRANS_LAST:
+        break;
+    }
+
+    VIR_DEBUG("adding gluster host for %p: transport=%s host=%s port=%d",
+              priv, transport, hoststr, port);
+
+    if (glfs_set_volfile_server(priv->vol, transport, hoststr, port) < 0) {
+        virReportSystemError(errno,
+                             _("failed to set gluster volfile server '%s'"),
+                             hoststr);
         return -1;
     }
 
-    hostname = host->name;
+    return 0;
+}
 
-    VIR_DEBUG("initializing gluster storage file %p (gluster://%s:%s/%s%s)[%u:%u]",
-              src, hostname, host->port ? host->port : "0",
-              NULLSTR(src->volume), src->path,
-              (unsigned int)src->drv->uid, (unsigned int)src->drv->gid);
+
+static int
+virStorageFileBackendGlusterInit(virStorageSourcePtr src)
+{
+    virStorageFileBackendGlusterPrivPtr priv = NULL;
+    size_t i;
 
     if (!src->volume) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
@@ -600,35 +630,25 @@ virStorageFileBackendGlusterInit(virStorageSourcePtr src)
     if (VIR_ALLOC(priv) < 0)
         return -1;
 
-    if (host->port &&
-        virStrToLong_i(host->port, NULL, 10, &port) < 0) {
-        virReportError(VIR_ERR_INTERNAL_ERROR,
-                       _("failed to parse port number '%s'"),
-                       host->port);
-        goto error;
-    }
-
-    if (host->transport == VIR_STORAGE_NET_HOST_TRANS_UNIX)
-        hostname = host->socket;
+    VIR_DEBUG("initializing gluster storage file %p "
+              "(priv='%p' volume='%s' path='%s') as [%u:%u]",
+              src, priv, src->volume, src->path,
+              (unsigned int)src->drv->uid, (unsigned int)src->drv->gid);
 
     if (!(priv->vol = glfs_new(src->volume))) {
         virReportOOMError();
         goto error;
     }
 
-    if (glfs_set_volfile_server(priv->vol,
-                                virStorageNetHostTransportTypeToString(host->transport),
-                                hostname, port) < 0) {
-        virReportSystemError(errno,
-                             _("failed to set gluster volfile server '%s'"),
-                             hostname);
-        goto error;
+    for (i = 0; i < src->nhosts; i++) {
+        if (virStorageFileBackendGlusterInitServer(priv, src->hosts + i) < 0)
+            goto error;
     }
 
     if (glfs_init(priv->vol) < 0) {
         virReportSystemError(errno,
-                             _("failed to initialize gluster connection to "
-                               "server: '%s'"), hostname);
+                             _("failed to initialize gluster connection "
+                               "(src=%p priv=%p)"), src, priv);
         goto error;
     }