Commit 8a388c1f authored by Chuck Lever's avatar Chuck Lever
Browse files

NFSD: Skip sending CB_RECALL_ANY when the backchannel isn't up 



NFSD sends CB_RECALL_ANY to clients when the server is low on
memory or that client has a large number of delegations outstanding.

We've seen cases where NFSD attempts to send CB_RECALL_ANY requests
to disconnected clients, and gets confused. These calls never go
anywhere if a backchannel transport to the target client isn't
available. Before the server can send any backchannel operation, the
client has to connect first and then do a BIND_CONN_TO_SESSION.

This patch doesn't address the root cause of the confusion, but
there's no need to queue up these optional operations if they can't
go anywhere.

Fixes: 44df6f43 ("NFSD: add delegation reaper to react to low memory condition")
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 45de52d0

fs/nfsd/nfs4state.c

+12 −7
Original line number Diff line number Diff line
@@ -6861,14 +6861,19 @@ deleg_reaper(struct nfsd_net *nn) 
	spin_lock(&nn->client_lock);

	list_for_each_safe(pos, next, &nn->client_lru) {

		clp = list_entry(pos, struct nfs4_client, cl_lru);

		if (clp->cl_state != NFSD4_ACTIVE ||

			list_empty(&clp->cl_delegations) ||

			atomic_read(&clp->cl_delegs_in_recall) ||

			test_bit(NFSD4_CLIENT_CB_RECALL_ANY, &clp->cl_flags) ||

			(ktime_get_boottime_seconds() -

				clp->cl_ra_time < 5)) {



		if (clp->cl_state != NFSD4_ACTIVE)

			continue;

		if (list_empty(&clp->cl_delegations))

			continue;

		if (atomic_read(&clp->cl_delegs_in_recall))

			continue;

		if (test_bit(NFSD4_CLIENT_CB_RECALL_ANY, &clp->cl_flags))

			continue;

		if (ktime_get_boottime_seconds() - clp->cl_ra_time < 5)

			continue;

		if (clp->cl_cb_state != NFSD4_CB_UP)

			continue;

		}

		list_add(&clp->cl_ra_cblist, &cblist);



		/* release in nfsd4_cb_recall_any_release */