We have seen examples of NFSv4 client reconnections failing due to
client source port reuse combined with stateful TCP state tracking in
middleboxes.
Commit 0f7a622ca616 ("rpc: xs_bind - do not bind when requesting a
random ephemeral port"), commit 4dda9c8a5e34 ("SUNRPC: Set SO_REUSEPORT
socket option for TCP connections"), and commit 1f4c17a03ba7 ("SUNRPC:
Handle EADDRNOTAVAIL on connection failures") had unintended side effects
of making port reuse dependent on whether that client uses reserved or
non-reserved source ports.
This series fixes the observed NFSv4 client reconnect failures by
choosing a new source port regardless of which port range is in use
for RST or FIN terminating the prior connection. This series does
not restore the original always-reuse behavior that existed prior to
commits mentioned above.
Patch 1:
--------
SUNRPC: Need to reuse non-reserved port for reconnect
This patch restores the original behavior of port reuse in all
scenarios.
Patch 2:
--------
SUNRPC: Reconnect with new port on server initiated connection
termination
Client uses a new port only in cases where server has terminated
the connection explicitly using RST or FIN.
Proposed outcome with this patch series:
----------------------------------------
------------------------------------------------------------------
| Port type | Connection termination | Current | With this |
| | type | behavior | patch series |
------------------------------------------------------------------
| Reserved | Network partition-DROP | Reuse port | Reuse port |
------------------------------------------------------------------
| Reserved | FIN from server | Reuse port | New port |
------------------------------------------------------------------
| Reserved | RST from server | Reuse port | New port |
------------------------------------------------------------------
| Non-Resv | Network partition-DROP | New port | Reuse port |
------------------------------------------------------------------
| Non-Resv | FIN from server | New port | New port |
------------------------------------------------------------------
| Non-Resv | RST from server | New port | New port |
------------------------------------------------------------------
net/sunrpc/xprtsock.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
--
2.7.3.AMZN
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