lvconvert: don't return success on degraded -m raid1 conversion

In case "lvconvert -mN RaidLV" was used on a degraded
raid1 LV, success was returned instead of an error.

Provide message to inform about the need to repair first
before changing number of mirrors and exit with error.

Add new lvconvert-m-raid1-degraded.sh test.

Resolves: rhbz1573960

1 files changed, 35 insertions, 1 deletions

diff --git a/lib/metadata/raid_manip.c b/lib/metadata/raid_manip.c
index 7d82a24b8..1b9ebcf94 100644
--- a/lib/metadata/raid_manip.c
+++ b/lib/metadata/raid_manip.c
@@ -3200,6 +3200,27 @@ static int _raid_remove_images(struct logical_volume *lv, int yes,
 	return 1;
 }
 
+/* Check if single SubLV @slv is degraded. */
+static int _sublv_is_degraded(const struct logical_volume *slv)
+{
+	return !slv || lv_is_partial(slv) || lv_is_virtual(slv);
+}
+
+/* Return failed component SubLV count for @lv. */
+static uint32_t _lv_get_nr_failed_components(const struct logical_volume *lv)
+{
+	uint32_t r = 0, s;
+	struct lv_segment *seg = first_seg(lv);
+
+	for (s = 0; s < seg->area_count; s++)
+		if (_sublv_is_degraded(seg_lv(seg, s)) ||
+		    (seg->meta_areas &&
+		     _sublv_is_degraded(seg_metalv(seg, s))))
+			r++;
+
+	return r;
+}
+
 /*
  * _lv_raid_change_image_count
  * new_count: The absolute count of images (e.g. '2' for a 2-way mirror)
@@ -3215,12 +3236,25 @@ static int _lv_raid_change_image_count(struct logical_volume *lv, int yes, uint3
 				       struct dm_list *allocate_pvs, struct dm_list *removal_lvs,
 				       int commit, int use_existing_area_len)
 {
+	int r;
 	uint32_t old_count = lv_raid_image_count(lv);
 
+	/* If there's failed component SubLVs, require repair first! */
+	if (lv_is_raid(lv) &&
+	    _lv_get_nr_failed_components(lv) &&
+	    new_count >= old_count) {
+		log_error("Can't change number of mirrors of degraded %s.",
+			  display_lvname(lv));
+		log_error("Please run \"lvconvert --repair %s\" first.",
+			  display_lvname(lv));
+		r = 0;
+	} else
+		r = 1;
+
 	if (old_count == new_count) {
 		log_warn("WARNING: %s already has image count of %d.",
 			 display_lvname(lv), new_count);
-		return 1;
+		return r;
 	}
 
 	/*