nfsd: move the confirmed and unconfirmed hlists to a rbtree

The current code requires that we md5 hash the name in order to store
the client in the confirmed and unconfirmed trees. Change it instead
to store the clients in a pair of rbtrees, and simply compare the
cl_names directly instead of hashing them. This also necessitates that
we add a new flag to the clp->cl_flags field to indicate which tree
the client is currently in.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

2 files changed, 95 insertions, 52 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 559ab574d46..99998a1eb42 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -412,10 +412,10 @@ static unsigned int clientstr_hashval(const char *name)
  * reclaim_str_hashtbl[] holds known client info from previous reset/reboot
  * used in reboot/reset lease grace period processing
  *
- * conf_id_hashtbl[], and conf_str_hashtbl[] hold confirmed
+ * conf_id_hashtbl[], and conf_name_tree hold confirmed
  * setclientid_confirmed info. 
  *
- * unconf_str_hastbl[] and unconf_id_hashtbl[] hold unconfirmed 
+ * unconf_id_hashtbl[] and unconf_name_tree hold unconfirmed
  * setclientid info.
  *
  * client_lru holds client queue ordered by nfs4_client.cl_time
@@ -423,13 +423,15 @@ static unsigned int clientstr_hashval(const char *name)
  *
  * close_lru holds (open) stateowner queue ordered by nfs4_stateowner.so_time
  * for last close replay.
+ *
+ * All of the above fields are protected by the client_mutex.
  */
 static struct list_head reclaim_str_hashtbl[CLIENT_HASH_SIZE];
 static int reclaim_str_hashtbl_size = 0;
 static struct list_head conf_id_hashtbl[CLIENT_HASH_SIZE];
-static struct list_head conf_str_hashtbl[CLIENT_HASH_SIZE];
-static struct list_head unconf_str_hashtbl[CLIENT_HASH_SIZE];
 static struct list_head unconf_id_hashtbl[CLIENT_HASH_SIZE];
+static struct rb_root conf_name_tree;
+static struct rb_root unconf_name_tree;
 static struct list_head client_lru;
 static struct list_head close_lru;
 
@@ -1144,7 +1146,10 @@ destroy_client(struct nfs4_client *clp)
         if (clp->cl_cb_conn.cb_xprt)
                 svc_xprt_put(clp->cl_cb_conn.cb_xprt);
         list_del(&clp->cl_idhash);
-        list_del(&clp->cl_strhash);
+        if (test_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags))
+                rb_erase(&clp->cl_namenode, &conf_name_tree);
+        else
+                rb_erase(&clp->cl_namenode, &unconf_name_tree);
         spin_lock(&client_lock);
         unhash_client_locked(clp);
         if (atomic_read(&clp->cl_refcount) == 0)
@@ -1187,6 +1192,17 @@ static int copy_cred(struct svc_cred *target, struct svc_cred *source)
         return 0;
 }
 
+static long long
+compare_blob(const struct xdr_netobj *o1, const struct xdr_netobj *o2)
+{
+        long long res;
+
+        res = o1->len - o2->len;
+        if (res)
+                return res;
+        return (long long)memcmp(o1->data, o2->data, o1->len);
+}
+
 static int same_name(const char *n1, const char *n2)
 {
         return 0 == memcmp(n1, n2, HEXDIR_LEN);
@@ -1307,7 +1323,6 @@ static struct nfs4_client *create_client(struct xdr_netobj name, char *recdir,
         atomic_set(&clp->cl_refcount, 0);
         clp->cl_cb_state = NFSD4_CB_UNKNOWN;
         INIT_LIST_HEAD(&clp->cl_idhash);
-        INIT_LIST_HEAD(&clp->cl_strhash);
         INIT_LIST_HEAD(&clp->cl_openowners);
         INIT_LIST_HEAD(&clp->cl_delegations);
         INIT_LIST_HEAD(&clp->cl_lru);
@@ -1325,11 +1340,52 @@ static struct nfs4_client *create_client(struct xdr_netobj name, char *recdir,
 }
 
 static void
-add_to_unconfirmed(struct nfs4_client *clp, unsigned int strhashval)
+add_clp_to_name_tree(struct nfs4_client *new_clp, struct rb_root *root)
+{
+        struct rb_node **new = &(root->rb_node), *parent = NULL;
+        struct nfs4_client *clp;
+
+        while (*new) {
+                clp = rb_entry(*new, struct nfs4_client, cl_namenode);
+                parent = *new;
+
+                if (compare_blob(&clp->cl_name, &new_clp->cl_name) > 0)
+                        new = &((*new)->rb_left);
+                else
+                        new = &((*new)->rb_right);
+        }
+
+        rb_link_node(&new_clp->cl_namenode, parent, new);
+        rb_insert_color(&new_clp->cl_namenode, root);
+}
+
+static struct nfs4_client *
+find_clp_in_name_tree(struct xdr_netobj *name, struct rb_root *root)
+{
+        long long cmp;
+        struct rb_node *node = root->rb_node;
+        struct nfs4_client *clp;
+
+        while (node) {
+                clp = rb_entry(node, struct nfs4_client, cl_namenode);
+                cmp = compare_blob(&clp->cl_name, name);
+                if (cmp > 0)
+                        node = node->rb_left;
+                else if (cmp < 0)
+                        node = node->rb_right;
+                else
+                        return clp;
+        }
+        return NULL;
+}
+
+static void
+add_to_unconfirmed(struct nfs4_client *clp)
 {
         unsigned int idhashval;
 
-        list_add(&clp->cl_strhash, &unconf_str_hashtbl[strhashval]);
+        clear_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags);
+        add_clp_to_name_tree(clp, &unconf_name_tree);
         idhashval = clientid_hashval(clp->cl_clientid.cl_id);
         list_add(&clp->cl_idhash, &unconf_id_hashtbl[idhashval]);
         renew_client(clp);
@@ -1339,12 +1395,12 @@ static void
 move_to_confirmed(struct nfs4_client *clp)
 {
         unsigned int idhashval = clientid_hashval(clp->cl_clientid.cl_id);
-        unsigned int strhashval;
 
         dprintk("NFSD: move_to_confirm nfs4_client %p\n", clp);
         list_move(&clp->cl_idhash, &conf_id_hashtbl[idhashval]);
-        strhashval = clientstr_hashval(clp->cl_recdir);
-        list_move(&clp->cl_strhash, &conf_str_hashtbl[strhashval]);
+        rb_erase(&clp->cl_namenode, &unconf_name_tree);
+        add_clp_to_name_tree(clp, &conf_name_tree);
+        set_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags);
         renew_client(clp);
 }
 
@@ -1387,27 +1443,15 @@ static bool clp_used_exchangeid(struct nfs4_client *clp)
 } 
 
 static struct nfs4_client *
-find_confirmed_client_by_str(const char *dname, unsigned int hashval)
+find_confirmed_client_by_name(struct xdr_netobj *name)
 {
-        struct nfs4_client *clp;
-
-        list_for_each_entry(clp, &conf_str_hashtbl[hashval], cl_strhash) {
-                if (same_name(clp->cl_recdir, dname))
-                        return clp;
-        }
-        return NULL;
+        return find_clp_in_name_tree(name, &conf_name_tree);
 }
 
 static struct nfs4_client *
-find_unconfirmed_client_by_str(const char *dname, unsigned int hashval)
+find_unconfirmed_client_by_name(struct xdr_netobj *name)
 {
-        struct nfs4_client *clp;
-
-        list_for_each_entry(clp, &unconf_str_hashtbl[hashval], cl_strhash) {
-                if (same_name(clp->cl_recdir, dname))
-                        return clp;
-        }
-        return NULL;
+        return find_clp_in_name_tree(name, &unconf_name_tree);
 }
 
 static void
@@ -1572,7 +1616,6 @@ nfsd4_exchange_id(struct svc_rqst *rqstp,
 {
         struct nfs4_client *unconf, *conf, *new;
         __be32 status;
-        unsigned int            strhashval;
         char                    dname[HEXDIR_LEN];
         char                    addr_str[INET6_ADDRSTRLEN];
         nfs4_verifier           verf = exid->verifier;
@@ -1605,11 +1648,9 @@ nfsd4_exchange_id(struct svc_rqst *rqstp,
         if (status)
                 return status;
 
-        strhashval = clientstr_hashval(dname);
-
         /* Cases below refer to rfc 5661 section 18.35.4: */
         nfs4_lock_state();
-        conf = find_confirmed_client_by_str(dname, strhashval);
+        conf = find_confirmed_client_by_name(&exid->clname);
         if (conf) {
                 bool creds_match = same_creds(&conf->cl_cred, &rqstp->rq_cred);
                 bool verfs_match = same_verf(&verf, &conf->cl_verifier);
@@ -1654,7 +1695,7 @@ nfsd4_exchange_id(struct svc_rqst *rqstp,
                 goto out;
         }
 
-        unconf  = find_unconfirmed_client_by_str(dname, strhashval);
+        unconf  = find_unconfirmed_client_by_name(&exid->clname);
         if (unconf) /* case 4, possible retry or client restart */
                 expire_client(unconf);
 
@@ -1668,7 +1709,7 @@ out_new:
         new->cl_minorversion = 1;
 
         gen_clid(new);
-        add_to_unconfirmed(new, strhashval);
+        add_to_unconfirmed(new);
 out_copy:
         exid->clientid.cl_boot = new->cl_clientid.cl_boot;
         exid->clientid.cl_id = new->cl_clientid.cl_id;
@@ -1789,7 +1830,6 @@ nfsd4_create_session(struct svc_rqst *rqstp,
                         goto out_free_conn;
                 }
         } else if (unconf) {
-                unsigned int hash;
                 struct nfs4_client *old;
                 if (!same_creds(&unconf->cl_cred, &rqstp->rq_cred) ||
                     !rpc_cmp_addr(sa, (struct sockaddr *) &unconf->cl_addr)) {
@@ -1803,8 +1843,7 @@ nfsd4_create_session(struct svc_rqst *rqstp,
                         status = nfserr_seq_misordered;
                         goto out_free_conn;
                 }
-                hash = clientstr_hashval(unconf->cl_recdir);
-                old = find_confirmed_client_by_str(unconf->cl_recdir, hash);
+                old = find_confirmed_client_by_name(&unconf->cl_name);
                 if (old)
                         expire_client(old);
                 move_to_confirmed(unconf);
@@ -2195,7 +2234,6 @@ nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 {
         struct xdr_netobj       clname = setclid->se_name;
         nfs4_verifier           clverifier = setclid->se_verf;
-        unsigned int            strhashval;
         struct nfs4_client      *conf, *unconf, *new;
         __be32                  status;
         char                    dname[HEXDIR_LEN];
@@ -2204,11 +2242,9 @@ nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
         if (status)
                 return status;
 
-        strhashval = clientstr_hashval(dname);
-
         /* Cases below refer to rfc 3530 section 14.2.33: */
         nfs4_lock_state();
-        conf = find_confirmed_client_by_str(dname, strhashval);
+        conf = find_confirmed_client_by_name(&clname);
         if (conf) {
                 /* case 0: */
                 status = nfserr_clid_inuse;
@@ -2223,7 +2259,7 @@ nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                         goto out;
                 }
         }
-        unconf = find_unconfirmed_client_by_str(dname, strhashval);
+        unconf = find_unconfirmed_client_by_name(&clname);
         if (unconf)
                 expire_client(unconf);
         status = nfserr_jukebox;
@@ -2237,7 +2273,7 @@ nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                 gen_clid(new);
         new->cl_minorversion = 0;
         gen_callback(new, setclid, rqstp);
-        add_to_unconfirmed(new, strhashval);
+        add_to_unconfirmed(new);
         setclid->se_clientid.cl_boot = new->cl_clientid.cl_boot;
         setclid->se_clientid.cl_id = new->cl_clientid.cl_id;
         memcpy(setclid->se_confirm.data, new->cl_confirm.data, sizeof(setclid->se_confirm.data));
@@ -2290,9 +2326,7 @@ nfsd4_setclientid_confirm(struct svc_rqst *rqstp,
                 nfsd4_probe_callback(conf);
                 expire_client(unconf);
         } else { /* case 3: normal case; new or rebooted client */
-                unsigned int hash = clientstr_hashval(unconf->cl_recdir);
-
-                conf = find_confirmed_client_by_str(unconf->cl_recdir, hash);
+                conf = find_confirmed_client_by_name(&unconf->cl_name);
                 if (conf)
                         expire_client(conf);
                 move_to_confirmed(unconf);
@@ -4706,11 +4740,11 @@ nfs4_state_init(void)
 
         for (i = 0; i < CLIENT_HASH_SIZE; i++) {
                 INIT_LIST_HEAD(&conf_id_hashtbl[i]);
-                INIT_LIST_HEAD(&conf_str_hashtbl[i]);
-                INIT_LIST_HEAD(&unconf_str_hashtbl[i]);
                 INIT_LIST_HEAD(&unconf_id_hashtbl[i]);
                 INIT_LIST_HEAD(&reclaim_str_hashtbl[i]);
         }
+        conf_name_tree = RB_ROOT;
+        unconf_name_tree = RB_ROOT;
         for (i = 0; i < SESSION_HASH_SIZE; i++)
                 INIT_LIST_HEAD(&sessionid_hashtbl[i]);
         for (i = 0; i < FILE_HASH_SIZE; i++) {
@@ -4795,6 +4829,7 @@ out_recovery:
         return ret;
 }
 
+/* should be called with the state lock held */
 static void
 __nfs4_state_shutdown(void)
 {
@@ -4802,17 +4837,24 @@ __nfs4_state_shutdown(void)
         struct nfs4_client *clp = NULL;
         struct nfs4_delegation *dp = NULL;
         struct list_head *pos, *next, reaplist;
+        struct rb_node *node, *tmp;
 
         for (i = 0; i < CLIENT_HASH_SIZE; i++) {
                 while (!list_empty(&conf_id_hashtbl[i])) {
                         clp = list_entry(conf_id_hashtbl[i].next, struct nfs4_client, cl_idhash);
                         destroy_client(clp);
                 }
-                while (!list_empty(&unconf_str_hashtbl[i])) {
-                        clp = list_entry(unconf_str_hashtbl[i].next, struct nfs4_client, cl_strhash);
-                        destroy_client(clp);
-                }
         }
+
+        node = rb_first(&unconf_name_tree);
+        while (node != NULL) {
+                tmp = node;
+                node = rb_next(tmp);
+                clp = rb_entry(tmp, struct nfs4_client, cl_namenode);
+                rb_erase(tmp, &unconf_name_tree);
+                destroy_client(clp);
+        }
+
         INIT_LIST_HEAD(&reaplist);
         spin_lock(&recall_lock);
         list_for_each_safe(pos, next, &del_recall_lru) {
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index cf9f7ba4df8..6c342bd806e 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -232,7 +232,7 @@ struct nfsd4_sessionid {
  */
 struct nfs4_client {
         struct list_head        cl_idhash;      /* hash by cl_clientid.id */
-        struct list_head        cl_strhash;     /* hash by cl_name */
+        struct rb_node          cl_namenode;    /* link into by-name trees */
         struct list_head        cl_openowners;
         struct idr              cl_stateids;    /* stateid lookup */
         struct list_head        cl_delegations;
@@ -253,6 +253,7 @@ struct nfs4_client {
 #define NFSD4_CLIENT_CB_KILL            (1)
 #define NFSD4_CLIENT_STABLE             (2)     /* client on stable storage */
 #define NFSD4_CLIENT_RECLAIM_COMPLETE   (3)     /* reclaim_complete done */
+#define NFSD4_CLIENT_CONFIRMED          (4)     /* client is confirmed */
 #define NFSD4_CLIENT_CB_FLAG_MASK       (1 << NFSD4_CLIENT_CB_UPDATE | \
                                          1 << NFSD4_CLIENT_CB_KILL)
         unsigned long           cl_flags;