On Tue, Mar 29, 2022 at 11:19:51AM -0700, dai.ngo@xxxxxxxxxx wrote:
>
> On 3/29/22 9:30 AM, J. Bruce Fields wrote:
> >On Tue, Mar 29, 2022 at 09:20:02AM -0700, dai.ngo@xxxxxxxxxx wrote:
> >>On 3/29/22 8:47 AM, J. Bruce Fields wrote:
> >>>On Thu, Mar 24, 2022 at 09:34:42PM -0700, Dai Ngo wrote:
> >>>>Update nfs4_client to add:
> >>>> . cl_cs_client_state: courtesy client state
> >>>> . cl_cs_lock: spinlock to synchronize access to cl_cs_client_state
> >>>> . cl_cs_list: list used by laundromat to process courtesy clients
> >>>>
> >>>>Modify alloc_client to initialize these fields.
> >>>>
> >>>>Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
> >>>>---
> >>>> fs/nfsd/nfs4state.c | 2 ++
> >>>> fs/nfsd/nfsd.h | 1 +
> >>>> fs/nfsd/state.h | 33 +++++++++++++++++++++++++++++++++
> >>>> 3 files changed, 36 insertions(+)
> >>>>
> >>>>diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> >>>>index 234e852fcdfa..a65d59510681 100644
> >>>>--- a/fs/nfsd/nfs4state.c
> >>>>+++ b/fs/nfsd/nfs4state.c
> >>>>@@ -2009,12 +2009,14 @@ static struct nfs4_client *alloc_client(struct xdr_netobj name)
> >>>> INIT_LIST_HEAD(&clp->cl_delegations);
> >>>> INIT_LIST_HEAD(&clp->cl_lru);
> >>>> INIT_LIST_HEAD(&clp->cl_revoked);
> >>>>+ INIT_LIST_HEAD(&clp->cl_cs_list);
> >>>> #ifdef CONFIG_NFSD_PNFS
> >>>> INIT_LIST_HEAD(&clp->cl_lo_states);
> >>>> #endif
> >>>> INIT_LIST_HEAD(&clp->async_copies);
> >>>> spin_lock_init(&clp->async_lock);
> >>>> spin_lock_init(&clp->cl_lock);
> >>>>+ spin_lock_init(&clp->cl_cs_lock);
> >>>> rpc_init_wait_queue(&clp->cl_cb_waitq, "Backchannel slot table");
> >>>> return clp;
> >>>> err_no_hashtbl:
> >>>>diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> >>>>index 4fc1fd639527..23996c6ca75e 100644
> >>>>--- a/fs/nfsd/nfsd.h
> >>>>+++ b/fs/nfsd/nfsd.h
> >>>>@@ -336,6 +336,7 @@ void nfsd_lockd_shutdown(void);
> >>>> #define COMPOUND_ERR_SLACK_SPACE 16 /* OP_SETATTR */
> >>>> #define NFSD_LAUNDROMAT_MINTIMEOUT 1 /* seconds */
> >>>>+#define NFSD_COURTESY_CLIENT_TIMEOUT (24 * 60 * 60) /* seconds */
> >>>> /*
> >>>> * The following attributes are currently not supported by the NFSv4 server:
> >>>>diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> >>>>index 95457cfd37fc..40e390abc842 100644
> >>>>--- a/fs/nfsd/state.h
> >>>>+++ b/fs/nfsd/state.h
> >>>>@@ -283,6 +283,35 @@ struct nfsd4_sessionid {
> >>>> #define HEXDIR_LEN 33 /* hex version of 16 byte md5 of cl_name plus '\0' */
> >>>> /*
> >>>>+ * CLIENT_ CLIENT_ CLIENT_
> >>>>+ * COURTESY EXPIRED RECONNECTED Meaning Where set
> >>>>+ * -----------------------------------------------------------------------------
> >>>>+ * | false | false | false | Confirmed, active | Default |
> >>>>+ * |---------------------------------------------------------------------------|
> >>>>+ * | true | false | false | Courtesy state. | nfs4_get_client_reaplist |
> >>>>+ * | | | | Lease/lock/share | |
> >>>>+ * | | | | reservation conflict | |
> >>>>+ * | | | | can cause Courtesy | |
> >>>>+ * | | | | client to be expired | |
> >>>>+ * |---------------------------------------------------------------------------|
> >>>>+ * | false | true | false | Courtesy client to be| nfs4_laundromat |
> >>>>+ * | | | | expired by Laundromat| nfsd4_lm_lock_expired |
> >>>>+ * | | | | due to conflict | nfsd4_discard_courtesy_clnt |
> >>>>+ * | | | | | nfsd4_expire_courtesy_clnt |
> >>>>+ * |---------------------------------------------------------------------------|
> >>>>+ * | false | false | true | Courtesy client | nfsd4_courtesy_clnt_expired|
> >>>>+ * | | | | reconnected, | |
> >>>>+ * | | | | becoming active | |
> >>>>+ * -----------------------------------------------------------------------------
> >By the way, where is a client returned to the normal (0) state? That
> >has to happen at some point.
>
> For 4.1 courtesy client reconnects is detected in nfsd4_sequence,
> nfsd4_bind_conn_to_session.
Those are the places where NFSD54_CLIENT_RECONNECTED is set, which isn't
the question I asked.
> >Why are RECONNECTED clients discarded in so many cases? (E.g. whenever
> >a bind_conn_to_session fails).
>
> find_in_sessionid_hashtbl: we discard the courtesy client when it
> reconnects and there is error from nfsd4_get_session_locked. This
> should be a rare condition so rather than reverting the client
> state back to courtesy, it is simpler just to discard it.
That may be a rare situation, but I don't believe the behavior of
discarding the client in this case is correct.
> nfsd4_create_session/find_confirmed_client: I think the only time
> the courtesy client sends CREATE_SESSION, before sending the SEQUENCE
> to reconnect after missing its leases, is when it wants to do clientid
> trunking. This should be a rare condition so instead of dealing
> with it we just do not allow it and discard the client for now.
We can't wave away incorrect behavior with "but it's rare". Users with
heavy and/or unusual workloads hit rare conditions. Clients may change
their behavior over time. (E.g., trunking may become more common.)
--b.
> nfsd4_destroy_clientid/find_confirmed_client: instead of destroy
> the courtesy client here we just let the laundromat destroy it
> as if the client already expired.
>
> nfsd4_setclientid_confirm/find_confirmed_client: there should not
> be any courtesy client found from nfsd4_setclientid_confirm, it
> should be detected and discarded in nfsd4_setclientid.
>
> -Dai
>
> >>>These are mutually exclusive values, not bits that may set to 0 or 1, so
> >>>the three boolean columns are confusing. I'd just structure the table
> >>>like:
> >>>
> >>> client state meaning where set
> >>> 0 Confirmed, active Default
> >>> CLIENT_COURTESY Courtesy state.... nfs4_get_client_reaplist
> >>> CLIENT_EXPIRED Courtesy client to be.. nfs4_laundromat
> >>>
> >>>etc.
> >>will fix in v19.
> >>
> >>Thanks,
> >>-Dai
> >>
> >>>--b.
> >>>
> >>>>+ */
> >>>>+
> >>>>+enum courtesy_client_state {
> >>>>+ NFSD4_CLIENT_COURTESY = 1,
> >>>>+ NFSD4_CLIENT_EXPIRED,
> >>>>+ NFSD4_CLIENT_RECONNECTED,
> >>>>+};
> >>>>+
> >>>>+/*
> >>>> * struct nfs4_client - one per client. Clientids live here.
> >>>> *
> >>>> * The initial object created by an NFS client using SETCLIENTID (for NFSv4.0)
> >>>>@@ -385,6 +414,10 @@ struct nfs4_client {
> >>>> struct list_head async_copies; /* list of async copies */
> >>>> spinlock_t async_lock; /* lock for async copies */
> >>>> atomic_t cl_cb_inflight; /* Outstanding callbacks */
> >>>>+
> >>>>+ enum courtesy_client_state cl_cs_client_state;
> >>>>+ spinlock_t cl_cs_lock;
> >>>>+ struct list_head cl_cs_list;
> >>>> };
> >>>> /* struct nfs4_client_reset
> >>>>--
> >>>>2.9.5
