dm persistent data: fix nested btree deletion

When deleting nested btrees, the code forgets to delete the innermost
btree.  The thin-metadata code serendipitously compensates for this by
claiming there is one extra layer in the tree.

This patch corrects both problems.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c
index 371f3d49d18..4caf66918cd 100644
--- a/drivers/md/persistent-data/dm-btree.c
+++ b/drivers/md/persistent-data/dm-btree.c
@@ -230,6 +230,11 @@ static void pop_frame(struct del_stack *s)
         dm_tm_unlock(s->tm, f->b);
 }
 
+static bool is_internal_level(struct dm_btree_info *info, struct frame *f)
+{
+        return f->level < (info->levels - 1);
+}
+
 int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
 {
         int r;
@@ -241,7 +246,7 @@ int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
         s->tm = info->tm;
         s->top = -1;
 
-        r = push_frame(s, root, 1);
+        r = push_frame(s, root, 0);
         if (r)
                 goto out;
 
@@ -267,7 +272,7 @@ int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
                         if (r)
                                 goto out;
 
-                } else if (f->level != (info->levels - 1)) {
+                } else if (is_internal_level(info, f)) {
                         b = value64(f->n, f->current_child);
                         f->current_child++;
                         r = push_frame(s, b, f->level + 1);