[dm-devel] [PATCH] block: trace completion of all bios.

[Christoph Hellwig]

On Wed, Mar 22, 2017 at 01:38:09PM +1100, NeilBrown wrote:
> 
> Currently only dm and md/raid5 bios trigger trace_block_bio_complete().
> Now that we have bio_chain(), it is not possible, in general, for a
> driver to know when the bio is really complete.  Only bio_endio()
> knows that.
> 
> So move the trace_block_bio_complete() call to bio_endio().

This will cause duplicate events for request based drivers.  You'll
need to have a bio_endio_notrace or similar without that the request
completion path can call.