[PATCH RFC 4/4] nfsd: keep a tally of RECLAIM_COMPLETE operations when using nfsdcld

Scott Mayhew
2018-11-06T18:35:14Z

When using nfsdcld for NFSv4 client tracking, track the number of
RECLAIM_COMPLETE operations we receive from "known" clients to help in
deciding if we can lift the grace period early (or whether we need to
start a v4 grace period at all).

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
---
fs/nfsd/netns.h | 3 +++
fs/nfsd/nfs4recover.c | 5 +++++
fs/nfsd/nfs4state.c | 52 +++++++++++++++++++++++++++++++++++++++++++
fs/nfsd/nfsctl.c | 1 +
4 files changed, 61 insertions(+)

diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index 32cb8c027483..b42aaa22fba2 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -104,6 +104,9 @@ struct nfsd_net {
time_t nfsd4_grace;
bool somebody_reclaimed;

+ bool track_reclaim_completes;
+ atomic_t nr_reclaim_complete;
+
bool nfsd_net_up;
bool lockd_up;

diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index 10887fdce8c2..171c013d63ba 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -1235,6 +1235,7 @@ nfsd4_cld_grace_done(struct nfsd_net *nn)
free_cld_upcall(cup);
out_err:
nfs4_release_reclaim(nn);
+ atomic_set(&nn->nr_reclaim_complete, 0);
if (ret)
printk(KERN_ERR "NFSD: Unable to end grace period: %d\n", ret);
}
@@ -1254,6 +1255,8 @@ nfs4_cld_state_init(struct net *net)
for (i = 0; i < CLIENT_HASH_SIZE; i++)
INIT_LIST_HEAD(&nn->reclaim_str_hashtbl[i]);
nn->reclaim_str_hashtbl_size = 0;
+ nn->track_reclaim_completes = true;
+ atomic_set(&nn->nr_reclaim_complete, 0);

return 0;
}
@@ -1263,6 +1266,7 @@ nfs4_cld_state_shutdown(struct net *net)
{
struct nfsd_net *nn = net_generic(net, nfsd_net_id);

+ nn->track_reclaim_completes = false;
kfree(nn->reclaim_str_hashtbl);
}

@@ -1302,6 +1306,7 @@ nfsd4_cld_tracking_exit(struct net *net)
struct nfsd_net *nn = net_generic(net, nfsd_net_id);

nfs4_release_reclaim(nn);
+ atomic_set(&nn->nr_reclaim_complete, 0);
nfsd4_remove_cld_pipe(net);
nfs4_cld_state_shutdown(net);
}
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 777fbb0d2761..5dfc3cd51d08 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -77,6 +77,7 @@ static u64 current_sessionid = 1;
/* forward declarations */
static bool check_for_locks(struct nfs4_file *fp, struct nfs4_lockowner *lowner);
static void nfs4_free_ol_stateid(struct nfs4_stid *stid);
+void nfsd4_end_grace(struct nfsd_net *nn);

/* Locking: */

@@ -1988,10 +1989,41 @@ destroy_client(struct nfs4_client *clp)
__destroy_client(clp);
}

+static void inc_reclaim_complete(struct nfs4_client *clp)
+{
+ struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
+
+ if (!nn->track_reclaim_completes)
+ return;
+ if (!test_bit(NFSD4_CLIENT_RECLAIM_COMPLETE, &clp->cl_flags))
+ return;
+ if (!nfsd4_find_reclaim_client(clp->cl_name, nn))
+ return;
+ if (atomic_inc_return(&nn->nr_reclaim_complete) ==
+ nn->reclaim_str_hashtbl_size) {
+ printk(KERN_INFO "NFSD: all clients done reclaiming, ending NFSv4 grace period (net %x)\n",
+ clp->net->ns.inum);
+ nfsd4_end_grace(nn);
+ }
+}
+
+static void dec_reclaim_complete(struct nfs4_client *clp)
+{
+ struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
+
+ if (!nn->track_reclaim_completes)
+ return;
+ if (!test_bit(NFSD4_CLIENT_RECLAIM_COMPLETE, &clp->cl_flags))
+ return;
+ if (nfsd4_find_reclaim_client(clp->cl_name, nn))
+ atomic_dec(&nn->nr_reclaim_complete);
+}
+
static void expire_client(struct nfs4_client *clp)
{
unhash_client(clp);
nfsd4_client_record_remove(clp);
+ dec_reclaim_complete(clp);
__destroy_client(clp);
}

@@ -3339,6 +3371,7 @@ nfsd4_reclaim_complete(struct svc_rqst *rqstp,

status = nfs_ok;
nfsd4_client_record_create(cstate->session->se_client);
+ inc_reclaim_complete(cstate->session->se_client);
out:
return status;
}
@@ -4734,6 +4767,10 @@ static bool clients_still_reclaiming(struct nfsd_net *nn)
unsigned long double_grace_period_end = nn->boot_time +
2 * nn->nfsd4_lease;

+ if (nn->track_reclaim_completes &&
+ atomic_read(&nn->nr_reclaim_complete) ==
+ nn->reclaim_str_hashtbl_size)
+ return false;
if (!nn->somebody_reclaimed)
return false;
nn->somebody_reclaimed = false;
@@ -7253,10 +7290,25 @@ nfs4_state_start_net(struct net *net)
return ret;
locks_start_grace(net, &nn->nfsd4_manager);
nfsd4_client_tracking_init(net);
+ if (nn->track_reclaim_completes && nn->reclaim_str_hashtbl_size == 0)
+ goto skip_grace;
printk(KERN_INFO "NFSD: starting %ld-second grace period (net %x)\n",
nn->nfsd4_grace, net->ns.inum);
queue_delayed_work(laundry_wq, &nn->laundromat_work, nn->nfsd4_grace * HZ);
return 0;
+
+skip_grace:
+ printk(KERN_INFO "NFSD: no clients to reclaim, skipping NFSv4 grace period (net %x)\n",
+ net->ns.inum);
+ queue_delayed_work(laundry_wq, &nn->laundromat_work, nn->nfsd4_lease * HZ);
+ /*
+ * we could call nfsd4_end_grace() here, but it has a dprintk()
+ * that would be confusing if debug logging is enabled
+ */
+ nn->grace_ended = true;
+ nfsd4_record_grace_done(nn);
+ locks_end_grace(&nn->nfsd4_manager);
+ return 0;
}

/* initialization to perform when the nfsd service is started: */
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 6384c9b94898..950ac6683be9 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1240,6 +1240,7 @@ static __net_init int nfsd_init_net(struct net *net)
nn->nfsd4_lease = 45; /* default lease time */
nn->nfsd4_grace = 45;
nn->somebody_reclaimed = false;
+ nn->track_reclaim_completes = false;
nn->clverifier_counter = prandom_u32();
nn->clientid_counter = prandom_u32();
nn->s2s_cp_cl_id = nn->clientid_counter++;
--
2.17.1