nvme-fc: rely on state transitions to handle connectivity loss

It's not possible to call nvme_state_ctrl_state with holding a spin
lock, because nvme_state_ctrl_state calls cancel_delayed_work_sync
when fastfail is enabled.

Instead syncing the ASSOC_FLAG and state transitions using a lock, it's
possible to only rely on the state machine transitions. That means
nvme_fc_ctrl_connectivity_loss should unconditionally call
nvme_reset_ctrl which avoids the read race on the ctrl state variable.
Actually, it's not necessary to test in which state the ctrl is, the
reset work will only scheduled when the state machine is in LIVE state.

In nvme_fc_create_association, the LIVE state can only be entered if it
was previously CONNECTING. If this is not possible then the reset
handler got triggered. Thus just error out here.

Fixes: ee59e382 ("nvme-fc: do not ignore connectivity loss during connecting")
Closes: https://lore.kernel.org/all/denqwui6sl5erqmz2gvrwueyxakl5txzbbiu3fgebryzrfxunm@iwxuthct377m/


Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Daniel Wagner <wagi@kernel.org>
Signed-off-by: Keith Busch <kbusch@kernel.org>