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

[Steve French]

On Tue, Feb 3, 2026 at 9:25 AM Stefan Metzmacher <metze at samba.org> wrote:
>
> Am 28.01.26 um 15:11 schrieb Leon Romanovsky:
> > On Wed, Jan 21, 2026 at 09:07:10PM +0100, Stefan Metzmacher wrote:
> >> 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()
> >
> > The approach looks reasonable.
>
> Thanks!
>
> > Do you want me to take it through RDMA
> > tree?
>
> As I also have other smb patches on top changing/using
> it I guess it would be easier if Steve would take them.
>
> Steve, Leon what do you think?

I am ok with taking it via the ksmbd tree (smb3-kernel ksmbd-for-next
branch), unless it is practical to merge the RDMA changes through the
RDMA tree in the first few days of the merge window and merge the
ksmbd-for-next branch a few days later (which sounds potentially
trickier)


-- 
Thanks,

Steve