[RFC PATCH 0/3] RDMA/smbdirect: introduce and use rdma_restrict_node_type()

[Stefan Metzmacher <metze@samba.org>]

Hi,

for smbdirect it required to use different ports depending
on the RDMA protocol. E.g. for iWarp 5445 is needed
(as tcp port 445 already used by the raw tcp transport for SMB),
while InfiniBand, RoCEv1 and RoCEv2 use port 445, as they
use an independent port range (even for RoCEv2, which uses udp
port 4791 itself).

Currently ksmbd is not able to function correctly at
all if the system has iWarp (RDMA_NODE_RNIC) interface(s)
and any InfiniBand, RoCEv1 and/or RoCEv2 interface(s)
at the same time.

And cifs.ko uses 5445 with a fallback to 445, which
means depending on the available interfaces, it tries
5445 in the RoCE range or may tries iWarp with 445
as a fallback. This leads to strange error messages
and strange network captures.

To avoid these problems they will be able to
use rdma_restrict_node_type(RDMA_NODE_RNIC) before
trying port 5445 and rdma_restrict_node_type(RDMA_NODE_IB_CA)
before trying port 445. It means we'll get early
-ENODEV early from rdma_resolve_addr() without any
network traffic and timeouts.

This is marked as RFC as I want to get feedback
if the rdma_restrict_node_type() function is acceptable
for the RDMA layer. And because the current form of
the smb patches are not tested, I only tested the
rdma part with my branch the prepares IPPROTO_SMBDIRECT
sockets.

I'm not sure if this would be acceptable for 6.19
in order to avoid the smb layer problems, if the
RDMA layer change is only acceptable for 7.0 that's
also fine.

This is based on the following fix applied:
smb: server: reset smb_direct_port = SMB_DIRECT_PORT_INFINIBAND on init
https://lore.kernel.org/linux-cifs/20251208154919.934760-1-metze@samba.org/
It's not yet in Linus' tree, so if this gets ready
before it's merged we can squash it.

Stefan Metzmacher (3):
  RDMA/core: introduce rdma_restrict_node_type()
  smb: client: make use of rdma_restrict_node_type()
  smb: server: make use of rdma_restrict_node_type()

 drivers/infiniband/core/cma.c      |  30 ++++++++
 drivers/infiniband/core/cma_priv.h |   1 +
 fs/smb/client/smbdirect.c          |  26 +++++++
 fs/smb/server/transport_rdma.c     | 108 +++++++++++++++++++++--------
 include/rdma/rdma_cm.h             |  17 +++++
 5 files changed, 154 insertions(+), 28 deletions(-)

-- 
2.43.0