Re: XFS Writes: IOLOCK_EXCL

[Steve Lord <lord@xxxxxxx>]

Nathan Scott wrote:
> I think its always valid to do this (after auditing the callers),
> but doesn't seem to do "general speedup" - the "usual suspects"
> benchmarks don't show any improvements anyway.  Alex, what was
> your workload?  (you didn't get back to me yet).
>
> cheers.
I missed the i_sem in nfs, did not look high enough up the stack.
Possibly the double flush in there was catching some extra data,
which considering we do this under the i_sem is somewhat unlikely.

The change would however allow reads to proceed across flushes
as the fsync_datawait which matters is now the one in the
fsync caller which is not holding any lock a read cares about.

Steve