From e0fcbae856454dba9df3f8df800d74fde66731e5 Mon Sep 17 00:00:00 2001

From: Vojtech Trefny <vtrefny@redhat.com>

Date: Tue, 31 Aug 2021 14:07:23 +0200

Subject: [PATCH] lvm: Fix reading statistics for VDO pools with VDO 8

The statistics are no longer available in /sys/kvdo, in the latest

version of kvdo we need to use /sys/block/<pool>/vdo/statistics.

Resolves: rhbz#1994220

---

 src/plugins/vdo_stats.c | 42 +++++++++++++++++++++++++++++++++++++----

 1 file changed, 38 insertions(+), 4 deletions(-)

diff --git a/src/plugins/vdo_stats.c b/src/plugins/vdo_stats.c

index ed04b51..2e244aa 100644

--- a/src/plugins/vdo_stats.c

+++ b/src/plugins/vdo_stats.c

@@ -133,6 +133,23 @@ static void add_computed_stats (GHashTable *stats) {

     add_journal_stats (stats);

 }

+static gchar* _dm_node_from_name (const gchar *map_name, GError **error) {

+    gchar *dev_path = NULL;

+    gchar *ret = NULL;

+    gchar *dev_mapper_path = g_strdup_printf ("/dev/mapper/%s", map_name);

+

+    dev_path = bd_utils_resolve_device (dev_mapper_path, error);

+    g_free (dev_mapper_path);

+    if (!dev_path)

+        /* error is already populated */

+        return NULL;

+

+    ret = g_path_get_basename (dev_path);

+    g_free (dev_path);

+

+    return ret;

+}

+

 GHashTable __attribute__ ((visibility ("hidden")))

 *vdo_get_stats_full (const gchar *name, GError **error) {

     GHashTable *stats;

@@ -141,14 +158,31 @@ GHashTable __attribute__ ((visibility ("hidden")))

     const gchar *direntry;

     gchar *s;

     gchar *val = NULL;

+    g_autofree gchar *dm_node = NULL;

-    /* TODO: does the `name` need to be escaped? */

-    stats_dir = g_build_path (G_DIR_SEPARATOR_S, VDO_SYS_PATH, name, "statistics", NULL);

+    /* try "new" (kvdo >= 8) path first -- /sys/block/dm-X/vdo/statistics */

+    dm_node = _dm_node_from_name (name, error);

+    if (dm_node == NULL) {

+        g_prefix_error (error, "Failed to get DM node for %s: ", name);

+        return NULL;

+    }

+

+    stats_dir = g_build_path (G_DIR_SEPARATOR_S, "/sys/block", dm_node, "vdo/statistics", NULL);

     dir = g_dir_open (stats_dir, 0, error);

     if (dir == NULL) {

-        g_prefix_error (error, "Error reading statistics from %s: ", stats_dir);

+        g_debug ("Failed to read VDO stats using the new API, falling back to %s: %s",

+                 VDO_SYS_PATH, (*error)->message);

         g_free (stats_dir);

-        return NULL;

+        g_clear_error (error);

+

+        /* lets try /sys/kvdo */

+        stats_dir = g_build_path (G_DIR_SEPARATOR_S, VDO_SYS_PATH, name, "statistics", NULL);

+        dir = g_dir_open (stats_dir, 0, error);

+        if (dir == NULL) {

+            g_prefix_error (error, "Error reading statistics from %s: ", stats_dir);

+            g_free (stats_dir);

+            return NULL;

+        }

     }

     stats = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);

-- 

2.31.1