Fix for bugs: 612248 & 612291 Split mirror issues

The main problem with these bugs was that the newly split
off LV was not being suspended properly.  This meant that
the memlock count was not being balanced, the DM devices
were not being renamed, and some DM devices which should
have been removed were not.

I've also renamed some of the variables and added comments
to make things clearer as to what is going on.  (I can break
this patch in two if it means easier review.)

diff --git a/WHATS_NEW b/WHATS_NEW
index f7cfce98410dfc4a7bffea5e39888225984e0440..a9b894cf2aaac24e549a1dfaaee08f43a4bcb32c 100644 (file)
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,5 +1,6 @@
 Version 2.02.71 -
 ===============================
+  Fix suspend/resume logic for LVs resulting from splitting a mirror.
   Switch cmirrord and clvmd to use dm_create_lockfile.
   Allow clvmd pidfile to be configurable.
   Update comments about memory handling in lvm2app.h.

diff --git a/lib/metadata/mirror.c b/lib/metadata/mirror.c
index 7bfb744af227a717992b8596e6949f7152e55213..0c4494b60912c6b68f9f6c431aba6edc446421b3 100644 (file)
--- a/lib/metadata/mirror.c
+++ b/lib/metadata/mirror.c
@@ -553,9 +553,9 @@ static int _split_mirror_images(struct logical_volume *lv,
                                struct dm_list *removable_pvs)
 {
        uint32_t i;
-       struct logical_volume *sub_lv, *new_lv = NULL;
+       struct logical_volume *sub_lv = NULL;
+       struct logical_volume *new_lv = NULL;
        struct logical_volume *detached_log_lv = NULL;
-       struct logical_volume *lv1 = NULL;
        struct lv_segment *mirrored_seg = first_seg(lv);
        struct dm_list split_images;
        struct lv_list *lvl;
@@ -597,6 +597,8 @@ static int _split_mirror_images(struct logical_volume *lv,
                release_lv_segment_area(mirrored_seg, mirrored_seg->area_count,
                                        mirrored_seg->area_len);
 
+               log_very_verbose("%s assigned to be split", sub_lv->name);
+
                if (!new_lv) {
                        new_lv = sub_lv;
                        new_lv->name = dm_pool_strdup(lv->vg->cmd->mem,
@@ -662,13 +664,19 @@ static int _split_mirror_images(struct logical_volume *lv,
                init_mirror_in_sync(1);
        }
 
-       /* If no more mirrors, remove mirror layer */
+       sub_lv = NULL;
+
+       /*
+        * If no more mirrors, remove mirror layer.
+        * The sub_lv is removed entirely later - leaving
+        * only the top-level (now linear) LV.
+        */
        if (mirrored_seg->area_count == 1) {
-               lv1 = seg_lv(mirrored_seg, 0);
-               lv1->status &= ~MIRROR_IMAGE;
-               lv_set_visible(lv1);
+               sub_lv = seg_lv(mirrored_seg, 0);
+               sub_lv->status &= ~MIRROR_IMAGE;
+               lv_set_visible(sub_lv);
                detached_log_lv = detach_mirror_log(mirrored_seg);
-               if (!remove_layer_from_lv(lv, lv1))
+               if (!remove_layer_from_lv(lv, sub_lv))
                        return_0;
                lv->status &= ~MIRRORED;
                lv->status &= ~MIRROR_NOTSYNCED;
@@ -679,6 +687,9 @@ static int _split_mirror_images(struct logical_volume *lv,
                return 0;
        }
 
+       /*
+        * Suspend the original device and all its sub devices
+        */
        if (!suspend_lv(mirrored_seg->lv->vg->cmd, mirrored_seg->lv)) {
                log_error("Failed to lock %s", mirrored_seg->lv->name);
                vg_revert(mirrored_seg->lv->vg);
@@ -690,35 +701,32 @@ static int _split_mirror_images(struct logical_volume *lv,
                return 0;
        }
 
-       log_very_verbose("Updating \"%s\" in kernel", mirrored_seg->lv->name);
-
        /*
-        * If we have split off a mirror instead of linear (i.e. the
-        * split_images list is not empty), then we must perform a
-        * resume to get the mirror started.
+        * Suspend the newly split-off LV (balance memlock count
+        * and prepare for DM automated renaming via resume).
         */
-       if (!dm_list_empty(&split_images) && !resume_lv(lv->vg->cmd, new_lv)) {
-               log_error("Failed to resume newly split LV, %s", new_lv->name);
+       if (!suspend_lv(lv->vg->cmd, new_lv)) {
+               log_error("Failed to lock newly split LV, %s", new_lv->name);
+               vg_revert(lv->vg);
                return 0;
        }
 
-       /*
-        * Avoid having same mirror target loaded twice simultaneously by first
-        * resuming the removed LV which now contains an error segment.
-        * As it's now detached from mirrored_seg->lv we must resume it
-        * explicitly.
-        */
-       if (lv1 && !resume_lv(lv1->vg->cmd, lv1)) {
-               log_error("Problem resuming temporary LV, %s", lv1->name);
+       /* Bring newly split-off LV into existence */
+       log_very_verbose("Creating %s", new_lv->name);
+       if (!resume_lv(lv->vg->cmd, new_lv)) {
+               log_error("Failed to activate newly split LV, %s",
+                         new_lv->name);
                return 0;
        }
 
+       /* Resume altered original LV */
+       log_very_verbose("Updating \"%s\" in kernel", mirrored_seg->lv->name);
        if (!resume_lv(mirrored_seg->lv->vg->cmd, mirrored_seg->lv)) {
                log_error("Problem reactivating %s", mirrored_seg->lv->name);
                return 0;
        }
 
-       if (lv1 && !_delete_lv(lv, lv1))
+       if (sub_lv && !_delete_lv(lv, sub_lv))
                return_0;
 
        if (detached_log_lv && !_delete_lv(lv, detached_log_lv))