Re: [Qemu-block] [PATCH 1/2] iotests: 030 TestParallelOps non-shared base node

[Alberto Garcia]

On Thu 21 Feb 2019 04:26:38 PM CET, Andrey Shinkevich wrote:
> The test case TestParallelOps::test_stream_parallel in #030 fails
> if a base node is protected by the block-stream running job that
> includes the base node into the job node list (block_job_add_bdrv)
> without BLK_PERM_GRAPH_MOD shared permission.
> The block-stream job would own the base node not allowing it to go
> away due to the graph modification, e.g. when a filter node is
> inserted above a top node of the parallel job. That's, the base
> node was shared between the two parallel jobs.
> This patch excludes sharing the node by inserting additional nodes
> inbetween.

So what we have now is:

   A <- B <- C <- D <- E <- F <- G <- H <- I

and we can launch four parallel block-stream jobs:

   From C (base) to A
   From E (base) to C
   From G (base) to E
   From I (base) to G

These jobs share nodes (the base node of each one is the active node of
the next), but that's ok. From the base node we only require that the
guest-visible data does not change.

If I understand it correctly your patch blocks the base node for the
stream job, so it's not possible to share it anymore like we are doing
now and you need to insert additional nodes.

This seems unnecessary. I wrote this test to check precisely that very
scenario. It works and I don't see any reason why it shouldn't. As I
said in the e-mail that I sent some minutes ago, if what we want is to
prevent the base node from disappearing it seems that we have better
tools for that now.

Berto