[libvirt] [PATCH 1/3] storage: add gluster backend initialization support for multiple servers

[Prasanna Kumar Kalever]

This patch adds support for initialization of gluster backend
with multiple servers which acts as gluster volfile servers for
the gluster storage backend.

This will help in achieving high availability of gluster backend
connectivity via libgfapi i.e. when the first volfile server fails,
then other servers specified are used as volfile server to re-establish
the backend gluster connectivity.

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever at redhat.com>
---
 src/storage/storage_backend_gluster.c | 77 +++++++++++++++++++----------------
 1 file changed, 41 insertions(+), 36 deletions(-)

diff --git a/src/storage/storage_backend_gluster.c b/src/storage/storage_backend_gluster.c
index d2e79bc..53474c1 100644
--- a/src/storage/storage_backend_gluster.c
+++ b/src/storage/storage_backend_gluster.c
@@ -32,6 +32,9 @@
 #include "virstring.h"
 #include "viruri.h"
 
+#define QEMU_DEFAULT_GLUSTER_PORT 24007
+#define QEMU_DEFAULT_GLUSTER_TRANSPORT "tcp"
+
 #define VIR_FROM_THIS VIR_FROM_STORAGE
 
 VIR_LOG_INIT("storage.storage_backend_gluster");
@@ -570,62 +573,64 @@ static int
 virStorageFileBackendGlusterInit(virStorageSourcePtr src)
 {
     virStorageFileBackendGlusterPrivPtr priv = NULL;
-    virStorageNetHostDefPtr host = &(src->hosts[0]);
-    const char *hostname;
+    const char *transport = NULL;
     int port = 0;
+    size_t i = 0;
 
-    if (src->nhosts != 1) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                       _("Expected exactly 1 host for the gluster volume"));
-        return -1;
-    }
-
-    hostname = host->name;
-
-    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);
+    VIR_DEBUG("Initializing gluster volume=%s image-path=%s with uid=%u gid=%u",
+            NULLSTR(src->volume), src->path,
+            (unsigned int)src->drv->uid, (unsigned int)src->drv->gid);
 
     if (!src->volume) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
-                       _("missing gluster volume name for path '%s'"),
-                       src->path);
+                _("missing gluster volume name for path '%s'"),
+                src->path);
         return -1;
     }
 
     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;
-
     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 (!src->hosts[i].port) {
+            port = QEMU_DEFAULT_GLUSTER_PORT;
+        } else if (virStrToLong_i(src->hosts[i].port, NULL, 10, &port) < 0) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                    _("failed to parse port number '%s'"), src->hosts[i].port);
+            goto error;
+        }
+
+        if (src->hosts[i].transport == VIR_STORAGE_NET_HOST_TRANS_UNIX) {
+            transport = src->hosts[i].socket;
+        } else if (!src->hosts[i].transport) {
+            transport = QEMU_DEFAULT_GLUSTER_TRANSPORT;
+        } else {
+            transport = virStorageNetHostTransportTypeToString(src->hosts[i].transport);
+        }
+
+        if (glfs_set_volfile_server(priv->vol, transport, src->hosts[i].name,
+                    port) < 0) {
+            virReportSystemError(errno,
+                    _("failed to set gluster volfile server '%s'"),
+                    src->hosts[i].name);
+            goto error;
+        } else {
+            VIR_DEBUG("Successfully set volfile server with server:'%s' "
+                    "port:'%d' transport:'%s'", src->hosts[i].name,
+                    port, transport);
+        }
     }
 
     if (glfs_init(priv->vol) < 0) {
         virReportSystemError(errno,
-                             _("failed to initialize gluster connection to "
-                               "server: '%s'"), hostname);
+                _("failed to initialize gluster connection with given hosts "
+                    "volume : '%s' image-path : '%s'"),
+                NULLSTR(src->volume), src->path);
         goto error;
     }
 
-- 
2.1.0