Re: [PATCH RFC] block: Revert 615939a2ae73

[Chengming Zhou <zhouchengming@bytedance.com>]

On 2023/8/10 05:49, Christoph Hellwig wrote:
> Oh well.  I don't feel like we're going to find the root cause
> given that its late in the merge window and I'm running out of
> time I have to work due to the annual summer vacation.  Unless
> someone like Chengming who knows the flush code pretty well
> feels like working with chuck on a few more iterations we'll

Hi,

No problem, I can work with Chuck to find the root cause if Chuck
has time too, since I still can't reproduce it by myself.

Maybe we should first find what's the status of the hang request?
I can write a Drgn script to find if any request hang in the queue.

Christoph, it would be very helpful if you share some thoughts
and directions.


> have to revert it.  Which is going to be a very painful merge
> with Chengming's work in the for-6.6 branch.
> 

Maybe we can revert it manually if we still fail since that commit
just let postflushes go to the normal I/O path, instead of going to
the flush state machine.

So I think it should be fine if we just delete that case?

Chuck, could you please help to check this change on block/for-next?

Thanks!

diff --git a/block/blk-flush.c b/block/blk-flush.c
index e73dc22d05c1..7ea3c00f40ce 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -442,17 +442,6 @@ bool blk_insert_flush(struct request *rq)
                 * Queue for normal execution.
                 */
                return false;
-       case REQ_FSEQ_DATA | REQ_FSEQ_POSTFLUSH:
-               /*
-                * Initialize the flush fields and completion handler to trigger
-                * the post flush, and then just pass the command on.
-                */
-               blk_rq_init_flush(rq);
-               rq->flush.seq |= REQ_FSEQ_PREFLUSH;
-               spin_lock_irq(&fq->mq_flush_lock);
-               fq->flush_data_in_flight++;
-               spin_unlock_irq(&fq->mq_flush_lock);
-               return false;
        default:
                /*
                 * Mark the request as part of a flush sequence and submit it