btrfs: fix folio refcount in __alloc_dummy_extent_buffer()

Another improper use of __folio_put() in an error path after freshly
allocating pages/folios which returns them with the refcount initialized
to 1. The refactor from __free_pages() -> __folio_put() (instead of
folio_put) removed a refcount decrement found in __free_pages() and
folio_put but absent from __folio_put().

Fixes: 13df377 ("btrfs: cleanup metadata page pointer usage")
CC: stable@vger.kernel.org # 6.8+
Tested-by: Ed Tomlinson <edtoml@gmail.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: boryas

fs/btrfs/extent_io.c

@@ -3553,7 +3553,7 @@ struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
 	for (int i = 0; i < num_folios; i++) {
 		if (eb->folios[i]) {
 			detach_extent_buffer_folio(eb, eb->folios[i]);
-			__folio_put(eb->folios[i]);
+			folio_put(eb->folios[i]);
 		}
 	}
 	__free_extent_buffer(eb);