[Qemu-block] [PATCH v9 16/31] quorum: Make bdrv_dirname() return NULL

[Max Reitz]

While the common implementation for bdrv_dirname() should return NULL
for quorum BDSs already (because they do not have a file node and their
exact_filename field should be empty), there is no reason not to make
that explicit.

Signed-off-by: Max Reitz <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Reviewed-by: Alberto Garcia <address@hidden>
---
 block/quorum.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/block/quorum.c b/block/quorum.c
index 03388590f3..beec8209d1 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -1101,6 +1101,16 @@ static void quorum_refresh_filename(BlockDriverState 
*bs, QDict *options)
     bs->full_open_options = opts;
 }
 
+static char *quorum_dirname(BlockDriverState *bs, Error **errp)
+{
+    /* In general, there are multiple BDSs with different dirnames below this
+     * one; so there is no unique dirname we could return (unless all are equal
+     * by chance, or there is only one). Therefore, to be consistent, just
+     * always return NULL. */
+    error_setg(errp, "Cannot generate a base directory for quorum nodes");
+    return NULL;
+}
+
 static BlockDriver bdrv_quorum = {
     .format_name                        = "quorum",
 
@@ -1109,6 +1119,7 @@ static BlockDriver bdrv_quorum = {
     .bdrv_open                          = quorum_open,
     .bdrv_close                         = quorum_close,
     .bdrv_refresh_filename              = quorum_refresh_filename,
+    .bdrv_dirname                       = quorum_dirname,
 
     .bdrv_co_flush_to_disk              = quorum_co_flush,
 
-- 
2.17.1