VMware, Inc.
Efficient handling of block write atomicity

Abstract:

A journal-based process to achieve atomicity in a device driver write operation includes committing a transaction associated with the operation to a journal that include a status indicating the target block is corrupted. Subsequent to committing the transaction, the data is written to the target block. If the write operation is successfully committed, the transaction can be deleted from the journal. If a system crash occurs (e.g., power failure) before the write operation is successfully committed, the transaction remains in the journal and can be used to update block metadata associated with the target block when the system reboots to indicate that it is corrupted; e.g., the target block is a torn write.