NBD client relies on lazy reconnection on error. There is a case where
nbd_co_establish_connection() will hand back a channel disconnected by
its peer. This leads to the request running on the dead channel. When
reconnect-delay is set to 0 (the default), this bug prevents the
nbd-connect thread from running on the first operation. This patch set
addresses this specific case.

Found while searching for a way to force client reconnection to simplify
the resize of idle nodes which will be the subject of another patch set.

v1: https://patchew.org/QEMU/20260925155346.357703-1-guillaume.vincke@ovhcloud.com/

v1 -> v2:
- patch 1: Pick up Eric Blake's formatting changes.
- patch 2: Start the connect thread after the NBD server so the test no
longer depends on the 1s connect retry, which made v1 fail in CI. Raise
the connect wait to 1s.

Guillaume Vincke (2):
  nbd/client-connection: Fix client returning a closed channel
  iotests: Add coverage for NBD connect thread start delay

 nbd/client-connection.c                       | 32 ++++++++++
 tests/qemu-iotests/tests/nbd-stale-connection | 60 +++++++++++++++++++
 .../tests/nbd-stale-connection.out            | 17 ++++++
 3 files changed, 109 insertions(+)
 create mode 100755 tests/qemu-iotests/tests/nbd-stale-connection
 create mode 100644 tests/qemu-iotests/tests/nbd-stale-connection.out

-- 
2.43.0