On Tue, 2022-08-30 at 12:14 -0700, Dai Ngo wrote:
> Add counter nfs4_courtesy_client_count to nfsd_net to keep track
> of the number of courtesy clients in the system.
>
> Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
> ---
> fs/nfsd/netns.h | 2 ++
> fs/nfsd/nfs4state.c | 14 +++++++++++---
> 2 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
> index ffe17743cc74..2695dff1378a 100644
> --- a/fs/nfsd/netns.h
> +++ b/fs/nfsd/netns.h
> @@ -192,6 +192,8 @@ struct nfsd_net {
>
> atomic_t nfs4_client_count;
> int nfs4_max_clients;
> +
> + atomic_t nfsd_courtesy_client_count;
> };
>
> /* Simple check to find out if a given net was properly initialized */
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index c5d199d7e6b4..9675b5d8f408 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -169,7 +169,8 @@ static __be32 get_client_locked(struct nfs4_client *clp)
> if (is_client_expired(clp))
> return nfserr_expired;
> atomic_inc(&clp->cl_rpc_users);
> - clp->cl_state = NFSD4_ACTIVE;
> + if (xchg(&clp->cl_state, NFSD4_ACTIVE) != NFSD4_ACTIVE)
> + atomic_add_unless(&nn->nfsd_courtesy_client_count, -1, 0);
I'd prefer this:
if (clp->cl_state != NFSD4_ACTIVE)
atomic_add_unless(...
clp->cl_state = NFSD4_ACTIVE;
It's more lines, but it's easier to read. It's may also be more
efficient since you're protected by a spinlock anyway.
I think it's also less deceptive when reading the code. When I see
xchg() operations being used like that, my immediate thought is that
they must be needed for synchronization purposes. It's not in this case.
> return nfs_ok;
> }
>
> @@ -190,7 +191,8 @@ renew_client_locked(struct nfs4_client *clp)
>
> list_move_tail(&clp->cl_lru, &nn->client_lru);
> clp->cl_time = ktime_get_boottime_seconds();
> - clp->cl_state = NFSD4_ACTIVE;
> + if (xchg(&clp->cl_state, NFSD4_ACTIVE) != NFSD4_ACTIVE)
> + atomic_add_unless(&nn->nfsd_courtesy_client_count, -1, 0);
> }
>
> static void put_client_renew_locked(struct nfs4_client *clp)
> @@ -2233,6 +2235,8 @@ __destroy_client(struct nfs4_client *clp)
> if (clp->cl_cb_conn.cb_xprt)
> svc_xprt_put(clp->cl_cb_conn.cb_xprt);
> atomic_add_unless(&nn->nfs4_client_count, -1, 0);
> + if (clp->cl_state != NFSD4_ACTIVE)
> + atomic_add_unless(&nn->nfsd_courtesy_client_count, -1, 0);
> free_client(clp);
> wake_up_all(&expiry_wq);
> }
> @@ -4356,6 +4360,8 @@ void nfsd4_init_leases_net(struct nfsd_net *nn)
> max_clients = (u64)si.totalram * si.mem_unit / (1024 * 1024 * 1024);
> max_clients *= NFS4_CLIENTS_PER_GB;
> nn->nfs4_max_clients = max_t(int, max_clients, NFS4_CLIENTS_PER_GB);
> +
> + atomic_set(&nn->nfsd_courtesy_client_count, 0);
> }
>
> static void init_nfs4_replay(struct nfs4_replay *rp)
> @@ -5879,7 +5885,9 @@ nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist,
> if (!state_expired(lt, clp->cl_time))
> break;
> if (!atomic_read(&clp->cl_rpc_users))
> - clp->cl_state = NFSD4_COURTESY;
> + if (xchg(&clp->cl_state, NFSD4_COURTESY) ==
> + NFSD4_ACTIVE)
> + atomic_inc(&nn->nfsd_courtesy_client_count);
> if (!client_has_state(clp))
> goto exp_client;
> if (!nfs4_anylock_blockers(clp))
--
Jeff Layton <jlayton@xxxxxxxxxx>
