In corruption cases we could have paths from a block up to no root at all, and thus we'll BUG_ON(!root) in select_one_root. Handle this by adding an ASSERT() for developers, and returning an error for normal users.
Signed-off-by: Josef Bacik <jo...@toxicpanda.com> --- fs/btrfs/relocation.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 8f7760f8fcc3..621c4284d158 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -2209,7 +2209,13 @@ struct btrfs_root *select_one_root(struct btrfs_backref_node *node) cond_resched(); next = walk_up_backref(next, edges, &index); root = next->root; - BUG_ON(!root); + + /* + * This can occur if we have incomplete extent refs leading all + * the way up a particular path, in this case return -EUCLEAN. + */ + if (!root) + return ERR_PTR(-EUCLEAN); /* No other choice for non-shareable tree */ if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) @@ -2599,8 +2605,15 @@ static int relocate_tree_block(struct btrfs_trans_handle *trans, BUG_ON(node->processed); root = select_one_root(node); - if (root == ERR_PTR(-ENOENT)) { - update_processed_blocks(rc, node); + if (IS_ERR(root)) { + ret = PTR_ERR(root); + + /* See explanation in select_one_root for the -EUCLEAN case. */ + ASSERT(ret == -ENOENT); + if (ret == -ENOENT) { + ret = 0; + update_processed_blocks(rc, node); + } goto out; } -- 2.26.2