pvscan: repopulate and reenable disabled lvmetad

Other commands ignore lvmetad when it's disabled,
but pvscan --cache is an exception since it is populating
the lvmetad cache, not using the lvmetad cache.

Have 'pvscan --cache' clear the disabled flag in lvmetad
if, after scanning all devices, it found no lvm1 metadata
and found no duplicate PVs.

3 files changed, 47 insertions, 1 deletions

diff --git a/lib/cache/lvmetad.c b/lib/cache/lvmetad.c
index 45b591193..c1ccdc340 100644
--- a/lib/cache/lvmetad.c
+++ b/lib/cache/lvmetad.c
@@ -35,6 +35,8 @@ static char *_lvmetad_token = NULL;
 static const char *_lvmetad_socket = NULL;
 static struct cmd_context *_lvmetad_cmd = NULL;
 
+static int _found_lvm1_metadata = 0;
+
 static struct volume_group *lvmetad_pvscan_vg(struct cmd_context *cmd, struct volume_group *vg);
 
 static int _log_debug_inequality(const char *name, struct dm_config_node *a, struct dm_config_node *b)
@@ -1381,6 +1383,7 @@ static struct volume_group *lvmetad_pvscan_vg(struct cmd_context *cmd, struct vo
 			lvmcache_fmt(info)->ops->destroy_instance(baton.fid);
 			log_warn("WARNING: Disabling lvmetad cache which does not support obsolete metadata.");
 			lvmetad_set_disabled(cmd, "LVM1");
+			_found_lvm1_metadata = 1;
 			return NULL;
 		}
 
@@ -1497,6 +1500,7 @@ int lvmetad_pvscan_single(struct cmd_context *cmd, struct device *dev,
 
 		log_warn("WARNING: Disabling lvmetad cache which does not support obsolete metadata.");
 		lvmetad_set_disabled(cmd, "LVM1");
+		_found_lvm1_metadata = 1;
 
 		if (ignore_obsolete)
 			return 1;
@@ -1551,6 +1555,7 @@ static int _lvmetad_pvscan_all_devs(struct cmd_context *cmd, activation_handler
 	daemon_reply reply;
 	int r = 1;
 	char *future_token;
+	const char *reason;
 	int was_silent;
 
 	if (!lvmetad_active()) {
@@ -1600,6 +1605,16 @@ static int _lvmetad_pvscan_all_devs(struct cmd_context *cmd, activation_handler
 	if (!_token_update())
 		return 0;
 
+	/*
+	 * If lvmetad is disabled, and no lvm1 metadata was seen and no
+	 * duplicate PVs were seen, then re-enable lvmetad.
+	 */
+	if (lvmetad_is_disabled(cmd, &reason) &&
+	    !lvmcache_found_duplicate_pvs() && !_found_lvm1_metadata) {
+		log_debug_lvmetad("Enabling lvmetad which was previously disabled.");
+		lvmetad_clear_disabled(cmd);
+	}
+
 	return r;
 }
 
@@ -1996,6 +2011,28 @@ void lvmetad_set_disabled(struct cmd_context *cmd, const char *reason)
 	daemon_reply_destroy(reply);
 }
 
+void lvmetad_clear_disabled(struct cmd_context *cmd)
+{
+	daemon_reply reply;
+
+	if (!_lvmetad_use)
+		return;
+
+	log_debug_lvmetad("lvmetad send disabled 0");
+
+	reply = daemon_send_simple(_lvmetad, "set_global_info",
+				   "token = %s", "skip",
+				   "global_disable = " FMTd64, (int64_t)0,
+				   NULL);
+	if (reply.error)
+		log_error("Failed to send message to lvmetad %d", reply.error);
+
+	if (strcmp(daemon_reply_str(reply, "response", ""), "OK"))
+		log_error("Failed response from lvmetad.");
+
+	daemon_reply_destroy(reply);
+}
+
 int lvmetad_is_disabled(struct cmd_context *cmd, const char **reason)
 {
 	daemon_reply reply;
diff --git a/lib/cache/lvmetad.h b/lib/cache/lvmetad.h
index 6345d9551..9e0f51a6f 100644
--- a/lib/cache/lvmetad.h
+++ b/lib/cache/lvmetad.h
@@ -180,6 +180,7 @@ int lvmetad_vg_is_foreign(struct cmd_context *cmd, const char *vgname, const cha
 
 int lvmetad_is_disabled(struct cmd_context *cmd, const char **reason);
 void lvmetad_set_disabled(struct cmd_context *cmd, const char *reason);
+void lvmetad_clear_disabled(struct cmd_context *cmd);
 
 #  else		/* LVMETAD_SUPPORT */
 
@@ -214,6 +215,7 @@ void lvmetad_set_disabled(struct cmd_context *cmd, const char *reason);
 #    define lvmetad_is_connected() (0)
 #    define lvmetad_is_disabled(cmd, reason) (0)
 #    define lvmetad_set_disabled(cmd, reason) do { } while (0)
+#    define lvmetad_clear_disabled(cmd) do { } while (0)
 
 #  endif	/* LVMETAD_SUPPORT */
 
diff --git a/tools/lvmcmdline.c b/tools/lvmcmdline.c
index d3d99f940..d21c4cf17 100644
--- a/tools/lvmcmdline.c
+++ b/tools/lvmcmdline.c
@@ -1643,7 +1643,14 @@ int lvm_run_command(struct cmd_context *cmd, int argc, char **argv)
 		goto_out;
 	}
 
-	if (lvmetad_is_connected() && lvmetad_is_disabled(cmd, &reason)) {
+	/*
+	 * If lvmetad is disabled, don't use it and revert to scanning.
+	 * The exception is pvscan which is explicitly repopulating
+	 * lvmetad, and may be able to clear the disabled setting.
+	 */
+	if (lvmetad_is_connected() &&
+	    !(cmd->command->flags & DISABLE_BUILTIN_PVSCAN) &&
+	    lvmetad_is_disabled(cmd, &reason)) {
 		log_warn("WARNING: Disabling use of lvmetad because %s.", reason);
 		lvmetad_set_active(cmd, 0);
 	}