Btrfs: always clear a block group node when removing it from the tree
Always clear a block group's rbnode after removing it from the rbtree to
ensure that any tasks that might be holding a reference on the block group
don't end up accessing stale rbnode left and right child pointers through
next_block_group().
This is a leftover from the change titled:
"Btrfs: fix invalid block group rbtree access after bg is removed"
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 222d6ae..974b3ed 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -8872,6 +8872,7 @@
cache_node);
rb_erase(&block_group->cache_node,
&info->block_group_cache_tree);
+ RB_CLEAR_NODE(&block_group->cache_node);
spin_unlock(&info->block_group_cache_lock);
down_write(&block_group->space_info->groups_sem);
@@ -9130,6 +9131,7 @@
spin_lock(&info->block_group_cache_lock);
rb_erase(&cache->cache_node,
&info->block_group_cache_tree);
+ RB_CLEAR_NODE(&cache->cache_node);
spin_unlock(&info->block_group_cache_lock);
btrfs_put_block_group(cache);
goto error;
@@ -9271,6 +9273,7 @@
spin_lock(&root->fs_info->block_group_cache_lock);
rb_erase(&cache->cache_node,
&root->fs_info->block_group_cache_tree);
+ RB_CLEAR_NODE(&cache->cache_node);
spin_unlock(&root->fs_info->block_group_cache_lock);
btrfs_put_block_group(cache);
return ret;