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Btrfs: always clear a block group node when removing it from the tree

Message ID 1417718310-13230-1-git-send-email-fdmanana@suse.com (mailing list archive)
State Accepted
Headers show

Commit Message

Filipe Manana Dec. 4, 2014, 6:38 p.m. UTC 
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>
---
 fs/btrfs/extent-tree.c | 3 +++
 1 file changed, 3 insertions(+)
diff mbox

Patch

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a7b81b4..c2fc261 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -8886,6 +8886,7 @@  int btrfs_free_block_groups(struct btrfs_fs_info *info)
 				       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);
@@ -9143,6 +9144,7 @@  int btrfs_read_block_groups(struct btrfs_root *root)
 			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;
@@ -9284,6 +9286,7 @@  int btrfs_make_block_group(struct btrfs_trans_handle *trans,
 		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;