[PATCH 6.1.y] btrfs: abort transaction on unexpected eb generation at btrfs_copy_root()

[Sasha Levin <sashal@kernel.org>]

From: Filipe Manana <fdmanana@suse.com>

[ Upstream commit 33e8f24b52d2796b8cfb28c19a1a7dd6476323a8 ]

If we find an unexpected generation for the extent buffer we are cloning
at btrfs_copy_root(), we just WARN_ON() and don't error out and abort the
transaction, meaning we allow to persist metadata with an unexpected
generation. Instead of warning only, abort the transaction and return
-EUCLEAN.

CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Daniel Vacek <neelx@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/btrfs/ctree.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index c7171b286de7..9620bf289f78 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -237,7 +237,14 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
 
 	write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
 
-	WARN_ON(btrfs_header_generation(buf) > trans->transid);
+	if (unlikely(btrfs_header_generation(buf) > trans->transid)) {
+		btrfs_tree_unlock(cow);
+		free_extent_buffer(cow);
+		ret = -EUCLEAN;
+		btrfs_abort_transaction(trans, ret);
+		return ret;
+	}
+
 	if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 		ret = btrfs_inc_ref(trans, root, cow, 1);
 	else
-- 
2.50.1