Yeah, but you can't remove the gap at all with start_freeze, that said
the current code has to live with the situation of new mapping change
and old request with old mapping.
Actually I considered to handle this kind of situation before, one approach
is to reuse the bio steal logic taken in nvme mpath:
1) for FS IO, re-submit bios, meantime free request
2) for PT request, simply fail it
It could be a bit violent for 2) even though REQ_FAILFAST_DRIVER is
always set for PT request, but not see any better approach for handling
PT request.
I think that's acceptable for PT requests, or any request that doesn't
have a bio. I tried something similiar a while back that was almost
working, but I neither never posted it, or it's in that window when
infradead lost all the emails. :(
Anyway, for the pci controller, I think I see the problem you're fixing.
When reset_work fails, we used to do the mark dead + unquieces via
"nvme_kill_queues()", which doesn't exist anymore, but I think your
scenario worked back then. Currently a failed nvme_reset_work simply
marks them dead without the unquiesce. Would it be enough to just bring
that unqueisce behavior back?
---
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index b027e5e3f4acb..8eaa954aa6ed4 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2778,6 +2778,7 @@ static void nvme_reset_work(struct work_struct *work)
nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_DELETING);
nvme_dev_disable(dev, true);
nvme_mark_namespaces_dead(&dev->ctrl);
+ nvme_unquiesce_io_queues(&dev->ctrl);
nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_DEAD);
}
--
I think this should work.
