On Sun, Aug 15, 2010 at 01:39:06PM -0400, Ted Ts'o wrote: > So after these ordering flush/ordering change that have been proposed, > if the block device layer is free to reorder the discard and a > subsequent write to a discard block, I will need to add a *new* wait > for the discard to complete before I can free the busy extent list. > And this will be true for all file systems that are currently issuing > discards. Again, am I missing something? The above is correct, except for the *new* part. sb_issue_discard at the moment is synchronous, so you're already waiting for it to finish. > So that means we need to add the end-io callbacks to the discard > operations *first*, before we remove the implicit flush/ordering > guarantees. Doing the discard asynchronous and with and end_io callback defintivel is an optimization over waiting for it synchronously, and it's in fact what I'm doing in XFS. It's however unrelated to getting rid of the barriers. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
