nfsd: Protect adding/removing open state owners using client_lock

Once we remove client mutex protection, we'll need to ensure that
stateowner lookup and creation are atomic between concurrent compounds.
Ensure that alloc_init_open_stateowner checks the hashtable under the
client_lock before adding a new element.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 6d26d26..c4bb7f2 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -239,6 +239,53 @@ static void nfsd4_put_session(struct nfsd4_session *ses)
        spin_unlock(&nn->client_lock);
 }
 
+static int
+same_owner_str(struct nfs4_stateowner *sop, struct xdr_netobj *owner,
+                                                       clientid_t *clid)
+{
+       return (sop->so_owner.len == owner->len) &&
+               0 == memcmp(sop->so_owner.data, owner->data, owner->len) &&
+               (sop->so_client->cl_clientid.cl_id == clid->cl_id);
+}
+
+static struct nfs4_openowner *
+find_openstateowner_str_locked(unsigned int hashval, struct nfsd4_open *open,
+                       bool sessions, struct nfsd_net *nn)
+{
+       struct nfs4_stateowner *so;
+       struct nfs4_openowner *oo;
+       struct nfs4_client *clp;
+
+       lockdep_assert_held(&nn->client_lock);
+
+       list_for_each_entry(so, &nn->ownerstr_hashtbl[hashval], so_strhash) {
+               if (!so->so_is_open_owner)
+                       continue;
+               if (same_owner_str(so, &open->op_owner, &open->op_clientid)) {
+                       oo = openowner(so);
+                       clp = oo->oo_owner.so_client;
+                       if ((bool)clp->cl_minorversion != sessions)
+                               break;
+                       renew_client_locked(clp);
+                       atomic_inc(&so->so_count);
+                       return oo;
+               }
+       }
+       return NULL;
+}
+
+static struct nfs4_openowner *
+find_openstateowner_str(unsigned int hashval, struct nfsd4_open *open,
+                       bool sessions, struct nfsd_net *nn)
+{
+       struct nfs4_openowner *oo;
+
+       spin_lock(&nn->client_lock);
+       oo = find_openstateowner_str_locked(hashval, open, sessions, nn);
+       spin_unlock(&nn->client_lock);
+       return oo;
+}
+
 
 static inline u32
 opaque_hashval(const void *ptr, int nbytes)
@@ -1005,8 +1052,13 @@ static void release_open_stateid(struct nfs4_ol_stateid *stp)
        nfs4_put_stid(&stp->st_stid);
 }
 
-static void unhash_openowner(struct nfs4_openowner *oo)
+static void unhash_openowner_locked(struct nfs4_openowner *oo)
 {
+       struct nfsd_net *nn = net_generic(oo->oo_owner.so_client->net,
+                                               nfsd_net_id);
+
+       lockdep_assert_held(&nn->client_lock);
+
        list_del_init(&oo->oo_owner.so_strhash);
        list_del_init(&oo->oo_perclient);
 }
@@ -1025,18 +1077,29 @@ static void release_last_closed_stateid(struct nfs4_openowner *oo)
 static void release_openowner_stateids(struct nfs4_openowner *oo)
 {
        struct nfs4_ol_stateid *stp;
+       struct nfsd_net *nn = net_generic(oo->oo_owner.so_client->net,
+                                               nfsd_net_id);
+
+       lockdep_assert_held(&nn->client_lock);
 
        while (!list_empty(&oo->oo_owner.so_stateids)) {
                stp = list_first_entry(&oo->oo_owner.so_stateids,
                                struct nfs4_ol_stateid, st_perstateowner);
+               spin_unlock(&nn->client_lock);
                release_open_stateid(stp);
+               spin_lock(&nn->client_lock);
        }
 }
 
 static void release_openowner(struct nfs4_openowner *oo)
 {
-       unhash_openowner(oo);
+       struct nfsd_net *nn = net_generic(oo->oo_owner.so_client->net,
+                                               nfsd_net_id);
+
+       spin_lock(&nn->client_lock);
+       unhash_openowner_locked(oo);
        release_openowner_stateids(oo);
+       spin_unlock(&nn->client_lock);
        release_last_closed_stateid(oo);
        nfs4_put_stateowner(&oo->oo_owner);
 }
@@ -3004,8 +3067,11 @@ static void hash_openowner(struct nfs4_openowner *oo, struct nfs4_client *clp, u
 static void nfs4_unhash_openowner(struct nfs4_stateowner *so)
 {
        struct nfs4_openowner *oo = openowner(so);
+       struct nfsd_net *nn = net_generic(so->so_client->net, nfsd_net_id);
 
-       unhash_openowner(oo);
+       spin_lock(&nn->client_lock);
+       unhash_openowner_locked(oo);
+       spin_unlock(&nn->client_lock);
 }
 
 static void nfs4_free_openowner(struct nfs4_stateowner *so)
@@ -3025,7 +3091,8 @@ alloc_init_open_stateowner(unsigned int strhashval, struct nfsd4_open *open,
                           struct nfsd4_compound_state *cstate)
 {
        struct nfs4_client *clp = cstate->clp;
-       struct nfs4_openowner *oo;
+       struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
+       struct nfs4_openowner *oo, *ret;
 
        oo = alloc_stateowner(openowner_slab, &open->op_owner, clp);
        if (!oo)
@@ -3039,7 +3106,15 @@ alloc_init_open_stateowner(unsigned int strhashval, struct nfsd4_open *open,
        oo->oo_time = 0;
        oo->oo_last_closed_stid = NULL;
        INIT_LIST_HEAD(&oo->oo_close_lru);
-       hash_openowner(oo, clp, strhashval);
+       spin_lock(&nn->client_lock);
+       ret = find_openstateowner_str_locked(strhashval,
+                       open, clp->cl_minorversion, nn);
+       if (ret == NULL) {
+               hash_openowner(oo, clp, strhashval);
+               ret = oo;
+       } else
+               nfs4_free_openowner(&oo->oo_owner);
+       spin_unlock(&nn->client_lock);
        return oo;
 }
 
@@ -3100,39 +3175,6 @@ move_to_close_lru(struct nfs4_ol_stateid *s, struct net *net)
        oo->oo_time = get_seconds();
 }
 
-static int
-same_owner_str(struct nfs4_stateowner *sop, struct xdr_netobj *owner,
-                                                       clientid_t *clid)
-{
-       return (sop->so_owner.len == owner->len) &&
-               0 == memcmp(sop->so_owner.data, owner->data, owner->len) &&
-               (sop->so_client->cl_clientid.cl_id == clid->cl_id);
-}
-
-static struct nfs4_openowner *
-find_openstateowner_str(unsigned int hashval, struct nfsd4_open *open,
-                       bool sessions, struct nfsd_net *nn)
-{
-       struct nfs4_stateowner *so;
-       struct nfs4_openowner *oo;
-       struct nfs4_client *clp;
-
-       list_for_each_entry(so, &nn->ownerstr_hashtbl[hashval], so_strhash) {
-               if (!so->so_is_open_owner)
-                       continue;
-               if (same_owner_str(so, &open->op_owner, &open->op_clientid)) {
-                       oo = openowner(so);
-                       clp = oo->oo_owner.so_client;
-                       if ((bool)clp->cl_minorversion != sessions)
-                               return NULL;
-                       renew_client(oo->oo_owner.so_client);
-                       atomic_inc(&oo->oo_owner.so_count);
-                       return oo;
-               }
-       }
-       return NULL;
-}
-
 /* search file_hashtbl[] for file */
 static struct nfs4_file *
 find_file_locked(struct knfsd_fh *fh)