mnesia: Avoid deadlock possibility in mnesia:del_table_copy schema

del_table_copy grabs a write lock in a new process in prepare_op/3 to
change 'where_to_read' when a table copy is updated.

When del_table_copy(schema, Node) is called all copies located on Node
are deleted, and thus many locks are taken. Since this was done outside
of the schema-transaction, mnesia's deadlock prevention algorithms
was sidestepped and a deadlock could occur.

Fix by always grabbing write-locks for all changed tabs early and in the same
transaction, this might slow done the operation some but it must be done
and it also cleans up the code.

0 files changed, 0 insertions, 0 deletions