Add a cl_use_count atomic counter to struct nfs4_client.
Hold a use count while the client is in use by a compound that begins
with SEQUENCE.
Renew the client when the comound completes.
The laundromat skips clients that have a positive use count.
Otherwise, the laundromat marks the client as expired by setting
cl_use_count to -1.
Note that we don't want to use the state lock to synchronize with nfsd4_sequence
as we want to diminish the state lock scope.
An alternative to using atomic_cmpxchg is to grab the sessionid_lock spin lock
while accessing cl_use_count, but that would cause some contention in the
laundromat if it needs to lock and unlock it for every client.
Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
---
fs/nfsd/nfs4state.c | 40 ++++++++++++++++++++++++++++++++++------
fs/nfsd/nfs4xdr.c | 2 ++
fs/nfsd/state.h | 9 +++++++++
3 files changed, 45 insertions(+), 6 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 50b75af..c95ddca 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -647,6 +647,14 @@ renew_client(struct nfs4_client *clp)
clp->cl_time = get_seconds();
}
+void
+renew_nfs4_client(struct nfs4_client *clp)
+{
+ nfs4_lock_state();
+ renew_client(clp);
+ nfs4_unlock_state();
+}
+
/* SETCLIENTID and SETCLIENTID_CONFIRM Helper functions */
static int
STALE_CLIENTID(clientid_t *clid)
@@ -715,6 +723,24 @@ put_nfs4_client(struct nfs4_client *clp)
free_client(clp);
}
+/*
+ * atomically mark client as used, as long as it's not already expired.
+ * return 0 on success, or a negative value if client already expired.
+ */
+int
+use_nfs4_client(struct nfs4_client *clp)
+{
+ int orig;
+
+ do {
+ orig = atomic_read(&clp->cl_use_count);
+ if (orig < 0)
+ return orig;
+ } while (atomic_cmpxchg(&clp->cl_use_count, orig, orig + 1) != orig);
+
+ return 0;
+}
+
static void
expire_client(struct nfs4_client *clp)
{
@@ -840,6 +866,7 @@ static struct nfs4_client *create_client(struct xdr_netobj name, char *recdir,
memcpy(clp->cl_recdir, recdir, HEXDIR_LEN);
atomic_set(&clp->cl_count, 1);
+ atomic_set(&clp->cl_use_count, 0);
atomic_set(&clp->cl_cb_conn.cb_set, 0);
INIT_LIST_HEAD(&clp->cl_idhash);
INIT_LIST_HEAD(&clp->cl_strhash);
@@ -1423,6 +1450,10 @@ nfsd4_sequence(struct svc_rqst *rqstp,
if (!session)
goto out;
+ /* keep the client from expiring */
+ if (use_nfs4_client(cstate->session->se_client) < 0)
+ goto out;
+
status = nfserr_badslot;
if (seq->slotid >= session->se_fchannel.maxreqs)
goto out;
@@ -1463,12 +1494,6 @@ out:
get_nfs4_client(cstate->session->se_client);
}
spin_unlock(&sessionid_lock);
- /* Renew the clientid on success and on replay */
- if (cstate->session) {
- nfs4_lock_state();
- renew_client(session->se_client);
- nfs4_unlock_state();
- }
dprintk("%s: return %d\n", __func__, ntohl(status));
return status;
}
@@ -2575,6 +2600,9 @@ nfs4_laundromat(void)
nfsd4_end_grace();
list_for_each_safe(pos, next, &client_lru) {
clp = list_entry(pos, struct nfs4_client, cl_lru);
+ /* skip client if in use (cl_use_count is greater than zero) */
+ if (atomic_cmpxchg(&clp->cl_use_count, 0, -1) > 0)
+ continue;
if (time_after((unsigned long)clp->cl_time, (unsigned long)cutoff)) {
t = clp->cl_time - cutoff;
if (clientid_val > t)
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index aed733c..0f0b857 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3313,6 +3313,8 @@ nfs4svc_encode_compoundres(struct svc_rqst *rqstp, __be32 *p, struct nfsd4_compo
dprintk("%s: SET SLOT STATE TO AVAILABLE\n", __func__);
cs->slot->sl_inuse = false;
}
+ renew_nfs4_client(cs->session->se_client);
+ unuse_nfs4_client(cs->session->se_client);
put_nfs4_client(cs->session->se_client);
nfsd4_put_session(cs->session);
}
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index e3c002e..806d9b8 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -214,6 +214,7 @@ struct nfs4_client {
nfs4_verifier cl_confirm; /* generated by server */
struct nfs4_cb_conn cl_cb_conn; /* callback info */
atomic_t cl_count; /* ref count */
+ atomic_t cl_use_count; /* session use count */
u32 cl_firststate; /* recovery dir creation */
/* for nfs41 */
@@ -237,6 +238,12 @@ get_nfs4_client(struct nfs4_client *clp)
atomic_inc(&clp->cl_count);
}
+static inline void
+unuse_nfs4_client(struct nfs4_client *clp)
+{
+ atomic_dec(&clp->cl_use_count);
+}
+
/* struct nfs4_client_reset
* one per old client. Populates reset_str_hashtbl. Filled from conf_id_hashtbl
* upon lease reset, or from upcall to state_daemon (to read in state
@@ -384,6 +391,8 @@ extern void nfs4_unlock_state(void);
extern int nfs4_in_grace(void);
extern __be32 nfs4_check_open_reclaim(clientid_t *clid);
extern void put_nfs4_client(struct nfs4_client *clp);
+extern int use_nfs4_client(struct nfs4_client *clp);
+extern void renew_nfs4_client(struct nfs4_client *clp);
extern void nfs4_free_stateowner(struct kref *kref);
extern int set_callback_cred(void);
extern void nfsd4_probe_callback(struct nfs4_client *clp);
--
1.6.3.3
--
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