1. A method comprising: executing a transactional memory (TM) transaction of an atomic section of code in a first thread within a processor; during the TM transaction, buffering a block of data in a first buffer of a cache memory of the processor responsive to determining that the block of data is sized to fit within the first buffer; and executing a first write barrier operation to acquire a write lock and a write monitor on the block to obtain ownership of the block at an encounter time in which data at a location of the block in the first buffer is updated.