bcachefs: Fix a KMSAN splat in btree_update_nodes_written()

We may sometimes read from uninitialized memory; we know, and that's ok.

We check if a btree node has been reused before waiting on any
outstanding IO.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2025-03-20 14:54:49 -04:00
commit 1f88c35674