Re: [PATCH v3] ocfs2: free unused clusters on defrag move errors

[Andrew Morton <akpm@linux-foundation.org>]

On Mon, 20 Jul 2026 22:19:43 +0800 Guangshuo Li <lgs201920130244@gmail.com> wrote:

> ocfs2_defrag_extent() claims new clusters before calling
> __ocfs2_move_extent(). If the move fails before ocfs2_split_extent()
> succeeds, the claimed clusters are not referenced by the inode and must
> be released.
> 
> The current error path only logs the error and continues to
> ocfs2_cow_sync_writeback(), which can overwrite the original error with
> zero and leave the claimed clusters allocated.
> 
> Not every __ocfs2_move_extent() error can free the new clusters. Once
> ocfs2_split_extent() succeeds, the extent tree references them even if
> ocfs2_decrease_refcount() or ocfs2_truncate_log_append() subsequently
> fails. Freeing the clusters in that case would leave the extent tree
> pointing to clusters marked free.
> 
> context->new_phys_cpos is updated immediately after a successful extent
> split. Compare it with the newly claimed physical cluster on error. If
> they differ, the split for the current move did not complete and the
> claimed clusters can be freed. If they match, leave the clusters
> allocated because the extent tree already references them.
> 
> Return move errors through the transaction cleanup path so that the
> original error is preserved instead of being overwritten by writeback.

Thanks.  AI review has flagged a couple of possible issues with this
change.  Please check?

	https://sashiko.dev/#/patchset/20260720141944.485212-1-lgs201920130244@gmail.com