[PATCH v2 0/8] fix possible controller reset hangs in nvme-tcp/nvme-rdma

[Sagi Grimberg]

When a controller reset runs during I/O we may hang if the controller
suddenly becomes unresponsive during the reset and/or the reconnection
stages. This is due to how the timeout handler did not fail inflight
commands properly and also not being able to abort the controller reset
sequence when the controller becomes unresponsive (hence can't ever
recover even if the controller ever becomes responsive again).

This set fixes nvme-tcp and nvme-rdma for exactly the same scenarios.

Patch 1 prevents commands being rejected by a live queue, making
commands mistakenly getting requeued forever while we are either
resetting or connecting to a controller.

Patch 2 lets consumers know if the freeze completed or a timeout
elapsed, will be used in patches 5,8.

Patches 3,4,6,7 fix the timeout handler in nvme-tcp and nvme-rdma
respectively to correctly and safely fail requests that are a
part of a serial (blocking) initialization or teardown sequences.

Patches 5,8 address the case when a controller stops responding when
we are in the middle of a connection establishment stage (tcp and rdma).

James, please have a look as well to see what needs to be addressed
for fc.

Changes from v1:
- added patches 3,6 to protect against possible (but rare) double
  completions for timed out requests.

Sagi Grimberg (8):
  nvme-fabrics: allow to queue requests for live queues
  nvme: have nvme_wait_freeze_timeout return if it timed out
  nvme-tcp: serialize controller teardown double completion
  nvme-tcp: fix timeout handler
  nvme-tcp: fix reset hang if controller died in the middle of a reset
  nvme-rdma: serialize controller teardown sequences
  nvme-rdma: fix timeout handler
  nvme-rdma: fix reset hang if controller died in the middle of a reset

 drivers/nvme/host/core.c    |  3 +-
 drivers/nvme/host/fabrics.c | 13 ++++--
 drivers/nvme/host/nvme.h    |  2 +-
 drivers/nvme/host/rdma.c    | 85 +++++++++++++++++++++++++--------
 drivers/nvme/host/tcp.c     | 93 ++++++++++++++++++++++++++++---------
 5 files changed, 147 insertions(+), 49 deletions(-)

-- 
2.25.1