btrfs_rebuild_free_space_tree() sets
BTRFS_FS_CREATING_FREE_SPACE_TREE before rebuilding the free space tree.
Several error paths return without clearing this flag.

The transaction restart failure path can leave the flag set on a live
filesystem, causing delayed reference processing to be skipped. Clear it
on all free space tree rebuild failure paths. Keep
BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED set, since a failed rebuild leaves the
free space tree untrusted. Callers must fall back to extent-tree caching.

Fixes: 882af9f13e83 ("btrfs: handle free space tree rebuild in multiple transactions")
Cc: stable@vger.kernel.org # 6.14+
Assisted-by: Codex:gpt-5
Tested: make -j$(nproc) fs/btrfs/free-space-tree.o
Signed-off-by: Guanghui Yang <3497809730@qq.com>
---
 fs/btrfs/free-space-tree.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/free-space-tree.c b/fs/btrfs/free-space-tree.c
index 1b3d82ae3de8..b7a4a6ade30f 100644
--- a/fs/btrfs/free-space-tree.c
+++ b/fs/btrfs/free-space-tree.c
@@ -1353,7 +1353,7 @@ int btrfs_rebuild_free_space_tree(struct btrfs_fs_info *fs_info)
 	if (unlikely(ret)) {
 		btrfs_abort_transaction(trans, ret);
 		btrfs_end_transaction(trans);
-		return ret;
+		goto out_clear;
 	}
 
 	node = rb_first_cached(&fs_info->block_group_cache_tree);
@@ -1371,14 +1371,16 @@ int btrfs_rebuild_free_space_tree(struct btrfs_fs_info *fs_info)
 		if (unlikely(ret)) {
 			btrfs_abort_transaction(trans, ret);
 			btrfs_end_transaction(trans);
-			return ret;
+			goto out_clear;
 		}
 next:
 		if (btrfs_should_end_transaction(trans)) {
 			btrfs_end_transaction(trans);
 			trans = btrfs_start_transaction(free_space_root, 1);
-			if (IS_ERR(trans))
-				return PTR_ERR(trans);
+			if (IS_ERR(trans)) {
+				ret = PTR_ERR(trans);
+				goto out_clear;
+			}
 		}
 		node = rb_next(node);
 	}
@@ -1390,6 +1392,10 @@ int btrfs_rebuild_free_space_tree(struct btrfs_fs_info *fs_info)
 	ret = btrfs_commit_transaction(trans);
 	clear_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
 	return ret;
+
+out_clear:
+	clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
+	return ret;
 }
 
 static int __add_block_group_free_space(struct btrfs_trans_handle *trans,

base-commit: 587858367581b9c55c3690f4e63382ad622719d4
-- 
2.34.1