On Mon, Jul 23, 2018 at 09:04:07AM -0400, Brian Foster wrote: > The dfops structure used by multi-transaction operations is > typically stored on the stack and carried around by the associated > transaction. The lifecycle of dfops does not quite match that of the > transaction, but they are tightly related in that the former depends > on the latter. > > The relationship of these objects is tight enough that we can avoid > the cumbersome boilerplate code required in most cases to manage > them separately by just embedding an xfs_defer_ops in the > transaction itself. This means that a transaction allocation returns > with an initialized dfops, a transaction commit finishes pending > deferred items before the tx commit, a transaction cancel cancels > the dfops before the transaction and a transaction dup operation > transfers the current dfops state to the new transaction. > > The dup operation is slightly complicated by the fact that we can no > longer just copy a dfops pointer from the old transaction to the new > transaction. This is solved through a dfops move helper that > transfers the pending items and other dfops state across the > transactions. This also requires that transaction rolling code > always refer to the transaction for the current dfops reference. > > Finally, to facilitate incremental conversion to the internal dfops > and continue to support the current external dfops mode of > operation, create the new ->t_dfops_internal field with a layer of > indirection. On allocation, ->t_dfops points to the internal dfops. > This state is overridden by callers who re-init a local dfops on the > transaction. Once ->t_dfops is overridden, the external dfops > reference is maintained as the transaction rolls. > > This patch adds the fundamental ability to support an internal > dfops. All codepaths that perform deferred processing continue to > override the internal dfops until they are converted over in > subsequent patches. > > Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx> Looks good, Reviewed-by: Christoph Hellwig <hch@xxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
