[libvirt] [PATCHv2] gluster: Fix "key" attribute for gluster volumes

[Peter Krempa]

According to our documentation the "key" value has the following
meaning: "Providing an identifier for the volume which identifies a
single volume." The currently used keys for gluster volumes consist of
the gluster volume name and file path. This can't be considered unique
as a different storage server can serve a volume with the same name.

Unfortunately I wasn't able to figure out a way to retrieve the gluster
volume UUID which would avoid the possibility of having two distinct
keys identifying a single volume.

Use the full URI as the key for the volume to avoid the more critical
ambiguity problem and document the possible change to UUID.
---
 docs/storage.html.in                  |  6 ++++--
 src/storage/storage_backend_gluster.c | 10 ++++++++--
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/docs/storage.html.in b/docs/storage.html.in
index 2706bc5..f75996a 100644
--- a/docs/storage.html.in
+++ b/docs/storage.html.in
@@ -711,8 +711,10 @@
       correspond to the files that can be found when mounting the
       gluster volume.  The <code>name</code> is the path relative to
       the effective mount specified for the pool; and
-      the <code>key</code> is a path including the gluster volume
-      name and any subdirectory specified by the pool.</p>
+      the <code>key</code> is a string that identifies a single volume
+      uniquely. Currently the <code>key</code> attribute consists of the
+      URI of the volume but it may be changed to an UUID of the volume
+      in the future.</p>
     <pre>
        <volume>
          <name>myfile</name>
diff --git a/src/storage/storage_backend_gluster.c b/src/storage/storage_backend_gluster.c
index a22b23a..06292fa 100644
--- a/src/storage/storage_backend_gluster.c
+++ b/src/storage/storage_backend_gluster.c
@@ -187,6 +187,7 @@ virStorageBackendGlusterSetMetadata(virStorageBackendGlusterStatePtr state,
                                     const char *name)
 {
     int ret = -1;
+    char *path = NULL;
     char *tmp;

     VIR_FREE(vol->key);
@@ -201,12 +202,12 @@ virStorageBackendGlusterSetMetadata(virStorageBackendGlusterStatePtr state,
             goto cleanup;
     }

-    if (virAsprintf(&vol->key, "%s%s%s", state->volname, state->dir,
+    if (virAsprintf(&path, "%s%s%s", state->volname, state->dir,
                     vol->name) < 0)
         goto cleanup;

     tmp = state->uri->path;
-    if (virAsprintf(&state->uri->path, "/%s", vol->key) < 0) {
+    if (virAsprintf(&state->uri->path, "/%s", path) < 0) {
         state->uri->path = tmp;
         goto cleanup;
     }
@@ -218,9 +219,14 @@ virStorageBackendGlusterSetMetadata(virStorageBackendGlusterStatePtr state,
     VIR_FREE(state->uri->path);
     state->uri->path = tmp;

+    /* the path is unique enough to serve as a volume key */
+    if (VIR_STRDUP(vol->key, vol->target.path) < 0)
+        goto cleanup;
+
     ret = 0;

 cleanup:
+    VIR_FREE(path);
     return ret;
 }

-- 
1.9.0