The function row_upd_clust_step() is invoking several static functions,
some of which used to commit the mini-transaction in some cases.
If innobase_get_computed_value() would fail due to some reason,
we would fail to invoke mtr_t::commit() and release buffer pool
page latches. This would likely lead to a hanging server later.
This regression was introduced in
commit 97db6c15ea (MDEV-20618).
row_upd_index_is_referenced(), row_upd_sec_index_entry(),
row_upd_sec_index_entry(): Cleanup: Replace some ibool with bool.
row_upd_clust_rec_by_insert(), row_upd_clust_rec(): Guarantee that
the mini-transaction will always remain in active state.
row_upd_del_mark_clust_rec(): Guarantee that
the mini-transaction will always remain in active state.
This fixes one "leak" of mini-transaction on DB_COMPUTE_VALUE_FAILED.
row_upd_clust_step(): Use only one return path, which will always
invoke mtr.commit(). After a failed row_upd_store_row() call, we
will no longer "leak" the mini-transaction.
This fix was verified by RQG on 10.6 (depending on MDEV-371 that
was introduced in 10.4). Unfortunately, it is challenging to
create a regression test for this, and a test case could soon become
invalid as more bugs in virtual column evaluation are fixed.