s3: Make sure our CLEAR_IF_FIRST optimization works for serverid.tdb

In the child, we fully re-open serverid.tdb, which leads to one fcntl lock for
CLEAR_IF_FIRST detection per smbd. This opens the tdb in the parent and holds
it, so that tdb_reopen_all correctly catches the CLEAR_IF_FIRST bit.

3 files changed, 25 insertions, 0 deletions

diff --git a/source3/include/serverid.h b/source3/include/serverid.h
index 9ef778cdc0..e60fc47afe 100644
--- a/source3/include/serverid.h
+++ b/source3/include/serverid.h
@@ -63,4 +63,9 @@ bool serverid_traverse_read(int (*fn)(const struct server_id *id,
 				      uint32_t msg_flags,
 				      void *private_data),
 			    void *private_data);
+/*
+ * Ensure CLEAR_IF_FIRST works fine, to be called from the parent smbd
+ */
+bool serverid_parent_init(void);
+
 #endif
diff --git a/source3/lib/serverid.c b/source3/lib/serverid.c
index 9842ead103..5401eed974 100644
--- a/source3/lib/serverid.c
+++ b/source3/lib/serverid.c
@@ -27,6 +27,22 @@ struct serverid_key {
 #endif
 };
 
+bool serverid_parent_init(void)
+{
+	struct tdb_wrap *db;
+
+	db = tdb_wrap_open(talloc_autofree_context(),
+			   lock_path("serverid.tdb"),
+			   0, TDB_DEFAULT|TDB_CLEAR_IF_FIRST, O_RDWR|O_CREAT,
+			   0644);
+	if (db == NULL) {
+		DEBUG(1, ("could not open serverid.tdb: %s\n",
+			  strerror(errno)));
+		return false;
+	}
+	return true;
+}
+
 struct serverid_data {
 	uint64_t unique_id;
 	uint32_t msg_flags;
diff --git a/source3/smbd/server.c b/source3/smbd/server.c
index 145dd5f5d5..e5cfc27794 100644
--- a/source3/smbd/server.c
+++ b/source3/smbd/server.c
@@ -1304,6 +1304,10 @@ extern void build_options(bool screen);
 		exit(1);
 	}
 
+	if (!serverid_parent_init()) {
+		exit(1);
+	}
+
 	namecache_enable();
 
 	if (!W_ERROR_IS_OK(registry_init_full()))