On Dec 10, 2023, at 9:55 AM, ditang chen [off-list ref] wrote:

Multiple nfs clients with the same hostname cause session exceptions,
the new client find confirmed nfs4_client by name in the
nfsd4_create_session
and then will release the se_hash list：

old = find_confirmed_client_by_name(&unconf->cl_name, nn);
if (old) {
   status = mark_client_expired_locked(old);
   if (status) {
       old = NULL;
       goto out_free_conn;
   }
   trace_nfsd_clid_replaced(&old->cl_clientid);
}
move_to_confirmed(unconf);

Is there any other option, such as IP instead of host name, which is
usually unique？

Yes.

The NFSv4 protocol needs each client to present a unique identifier
to a server in order for the server to collect open and lock state
belonging to that client. Typically the client's hostname is unique
enough for this purpose.

Sometimes, though, the client's hostname doesn't provide a globally
unique identity. Client implementations usually provide a secondary
way of identifying themselves. I can't give an exact recipe because
each client implementation has its own peculiar administrative
interface for this; and sometimes they have more than one, to deal
with things like containers (Linux) or zones (Solaris).

Look for something on your clients that enables you to set the
nfs4_client_id to something unique. You can use a random string
or "uuid -r" for this purpose. But each client instance needs to
have its own distinct nfs4_client_id.

Here's a general description of how this works on Linux NFS clients:

https://www.kernel.org/doc/html/latest/filesystems/nfs/client-identifier.html

HTH.

Dec  1 22:42:32 dd kernel: nfsd4_exchange_id rqstp=000000006668b520
exid=00000000a44d3b72 clname.len=35 clname.data=000000007b1b5592
ip_addr=192.168.122.130 flags 101, spa_how 0
Dec  1 22:42:32 dd kernel: nfsd4_exchange_id seqid 0 flags 20001
Dec  1 22:42:32 dd kernel: check_slot_seqid enter. seqid 1 slot_seqid 0
Dec  1 22:42:32 dd kernel: alloc_cld_upcall: allocated xid 10
Dec  1 22:42:32 dd rpc.mountd[25713]: v4.2 client attached:
0xe21bb8c66569eeaf from "192.168.122.130:894"
Dec  1 22:42:32 dd rpc.mountd[25713]: v4.2 client detached:
0xe21bb8c56569eeaf from "192.168.122.93:791"
Dec  1 22:42:32 dd kernel: __find_in_sessionid_hashtbl:
1701441199:3793467590:5:0
Dec  1 22:42:32 dd kernel: nfsd4_sequence: slotid 0
Dec  1 22:42:32 dd kernel: check_slot_seqid enter. seqid 1 slot_seqid 0
Dec  1 22:42:32 dd kernel: nfsd: fh_compose(exp 103:08/128 /, ino=128)
Dec  1 22:42:32 dd kernel: --> nfsd4_store_cache_entry slot 000000006ef6f422
Dec  1 22:42:32 dd kernel: __find_in_sessionid_hashtbl:
1701441199:3793467590:5:0
Dec  1 22:42:32 dd kernel: nfsd4_sequence: slotid 0
Dec  1 22:42:32 dd kernel: check_slot_seqid enter. seqid 2 slot_seqid 1
Dec  1 22:42:32 dd kernel: alloc_cld_upcall: allocated xid 11
Dec  1 22:42:32 dd kernel: --> nfsd4_store_cache_entry slot 000000006ef6f422
Dec  1 22:42:36 dd kernel: __find_in_sessionid_hashtbl:
1701441199:3793467589:4:0
Dec  1 22:42:36 dd kernel: __find_in_sessionid_hashtbl: session not found
Dec  1 22:42:36 dd kernel: nfsd4_destroy_session: 1701441199:3793467589:4:0
Dec  1 22:42:36 dd kernel: __find_in_sessionid_hashtbl:
1701441199:3793467589:4:0
Dec  1 22:42:36 dd kernel: __find_in_sessionid_hashtbl: session not found
Dec  1 22:42:36 dd kernel: nfsd4_exchange_id rqstp=000000006668b520
exid=00000000a44d3b72 clname.len=35 clname.data=000000007b1b5592
ip_addr=192.168.122.93 flags 101, spa_how 0
Dec  1 22:42:36 dd kernel: nfsd4_exchange_id seqid 0 flags 20001
Dec  1 22:42:36 dd kernel: check_slot_seqid enter. seqid 1 slot_seqid 0
Dec  1 22:42:36 dd kernel: alloc_cld_upcall: allocated xid 12
Dec  1 22:42:36 dd rpc.mountd[25713]: v4.2 client attached:
0xe21bb8c76569eeaf from "192.168.122.93:791"
Dec  1 22:42:36 dd rpc.mountd[25713]: v4.2 client detached:
0xe21bb8c66569eeaf from "192.168.122.130:894"
Dec  1 22:42:36 dd kernel: __find_in_sessionid_hashtbl:
1701441199:3793467591:6:0
Dec  1 22:42:36 dd kernel: nfsd4_sequence: slotid 0
Dec  1 22:42:36 dd kernel: check_slot_seqid enter. seqid 1 slot_seqid 0
Dec  1 22:42:36 dd kernel: nfsd: fh_compose(exp 103:08/128 /, ino=128)
Dec  1 22:42:36 dd kernel: --> nfsd4_store_cache_entry slot 00000000e1f66c24
Dec  1 22:42:36 dd kernel: __find_in_sessionid_hashtbl:
1701441199:3793467591:6:0
Dec  1 22:42:36 dd kernel: nfsd4_sequence: slotid 0
Dec  1 22:42:36 dd kernel: check_slot_seqid enter. seqid 2 slot_seqid 1
Dec  1 22:42:36 dd kernel: alloc_cld_upcall: allocated xid 13
Dec  1 22:42:36 dd kernel: --> nfsd4_store_cache_entry slot 00000000e1f66c24
Dec  1 22:43:33 dd kernel: __find_in_sessionid_hashtbl:
1701441199:3793467590:5:0
Dec  1 22:43:33 dd kernel: __find_in_sessionid_hashtbl: session not found
Dec  1 22:43:33 dd kernel: nfsd4_destroy_session: 1701441199:3793467590:5:0
Dec  1 22:43:33 dd kernel: __find_in_sessionid_hashtbl:
1701441199:3793467590:5:0
Dec  1 22:43:33 dd kernel: __find_in_sessionid_hashtbl: session not found

--
Chuck Lever