X-Git-Url: https://git.whamcloud.com/?a=blobdiff_plain;f=lustre%2Fptlrpc%2Fnodemap_member.c;h=9871f8d285ffdd980b15a3ea454ae0a285df1f21;hb=512f2ff1b17db4d03979a1caa86f94defc6653b4;hp=08b269b2a8d467c32f709875dfbb845dfd4b5fbd;hpb=83f04354ff68a14d7492e35a9576c91492a1206c;p=fs%2Flustre-release.git

diff --git a/lustre/ptlrpc/nodemap_member.c b/lustre/ptlrpc/nodemap_member.c
index 08b269b..9871f8d 100644
--- a/lustre/ptlrpc/nodemap_member.c
+++ b/lustre/ptlrpc/nodemap_member.c
@@ -50,7 +50,7 @@ void nm_member_putref(struct obd_export *exp)
 static __u32 nm_member_hashfn(cfs_hash_t *hash_body,
 			   const void *key, unsigned mask)
 {
-	return cfs_hash_djb2_hash(key, strlen(key), mask);
+	return hash_long((unsigned long)key, hash_body->hs_bkt_bits) & mask;
 }
 
 static void *nm_member_hs_key(struct hlist_node *hnode)
@@ -106,13 +106,14 @@ static void nm_member_hs_put_locked(cfs_hash_t *hs,
  */
 void nm_member_del(struct lu_nodemap *nodemap, struct obd_export *exp)
 {
+	struct obd_export *exp1;
 
-	exp->exp_target_data.ted_nodemap = NULL;
-	exp = cfs_hash_del_key(nodemap->nm_member_hash, exp);
-	if (exp == NULL)
-		return;
+	exp1 = cfs_hash_del_key(nodemap->nm_member_hash, exp);
+	if (exp1 != NULL)
+		class_export_put(exp1);
 
-	class_export_put(exp);
+	LASSERT(hlist_unhashed(&exp->exp_target_data.ted_nodemap_member));
+	exp->exp_target_data.ted_nodemap = NULL;
 }
 
 static cfs_hash_ops_t nm_member_hash_operations = {
@@ -219,7 +220,7 @@ int nm_member_add(struct lu_nodemap *nodemap, struct obd_export *exp)
 	rc = cfs_hash_add_unique(nodemap->nm_member_hash, exp,
 				 &exp->exp_target_data.ted_nodemap_member);
 
-	if (rc == 0 )
+	if (rc == 0)
 		class_export_get(exp);
 	/* else -EALREADY - exp already in nodemap hash */
 
@@ -246,39 +247,61 @@ static int nm_member_reclassify_cb(cfs_hash_t *hs, cfs_hash_bd_t *bd,
 				   struct hlist_node *hnode, void *data)
 {
 	struct obd_export	*exp;
+	struct lu_nodemap	*nodemap;
 
 	exp = hlist_entry(hnode, struct obd_export,
 			  exp_target_data.ted_nodemap_member);
 	if (exp == NULL)
 		goto out;
 
-	/* Call member add before del so exp->nodemap is never NULL. Must use
-	 * bd_del_locked inside a cfs_hash callback. For those reasons, can't
-	 * use member_del.
+	/* Must use bd_del_locked inside a cfs_hash callback, and exp->nodemap
+	 * should never be NULL. For those reasons, can't use member_del.
 	 */
-	nodemap_add_member(exp->exp_connection->c_peer.nid, exp);
-	cfs_hash_bd_del_locked(hs, bd, hnode);
-	class_export_put(exp);
+	read_lock(&nm_range_tree_lock);
+	nodemap = nodemap_classify_nid(exp->exp_connection->c_peer.nid);
+	if (exp->exp_target_data.ted_nodemap != nodemap) {
+		cfs_hash_bd_del_locked(hs, bd, hnode);
+		exp->exp_target_data.ted_nodemap = nodemap;
+		cfs_hash_add_unique(nodemap->nm_member_hash, exp,
+				&exp->exp_target_data.ted_nodemap_member);
+	}
+	read_unlock(&nm_range_tree_lock);
 
 	nm_member_exp_revoke(exp);
 out:
 	return 0;
 }
 
+/* Mutex used to serialize calls to reclassify_nodemap_lock */
+DEFINE_MUTEX(reclassify_nodemap_lock);
+
 /**
- * Reclassify the members of a nodemap after range changes or activation,
- * based on the member export's NID and the nodemap's new NID ranges. Exports
- * that are no longer classified as being part of this nodemap are moved to the
- * nodemap whose NID ranges contain the export's NID, and their locks are
- * revoked.
+ * Reclassify the members of a nodemap after range changes or activation.
+ * This function reclassifies the members of a nodemap based on the member
+ * export's NID and the nodemap's new NID ranges. Exports that are no longer
+ * classified as being part of this nodemap are moved to the nodemap whose
+ * NID ranges contain the export's NID, and their locks are revoked.
+ *
+ * Calls to this function are serialized due to a potential deadlock: Say there
+ * is a nodemap A and a nodemap B that both need to reclassify their members.
+ * If there is a member in nodemap A that should be in nodemap B, reclassify
+ * will attempt to add the member to nodemap B. If nodemap B is also
+ * reclassifying its members, then its hash is locked and nodemap A's attempt
+ * to add will block and wait for nodemap B's reclassify to finish. If
+ * nodemap B's reclassify then attempts to reclassify a member that should be
+ * in nodemap A, it will also try add the member to nodemap A's locked hash,
+ * causing a deadlock.
  *
  * \param	nodemap		nodemap with members to reclassify
  */
 void nm_member_reclassify_nodemap(struct lu_nodemap *nodemap)
 {
+	/* reclassify only one nodemap at a time to avoid deadlock */
+	mutex_lock(&reclassify_nodemap_lock);
 	cfs_hash_for_each_safe(nodemap->nm_member_hash,
 			       nm_member_reclassify_cb,
 			       NULL);
+	mutex_unlock(&reclassify_nodemap_lock);
 }
 
 static int nm_member_revoke_locks_cb(cfs_hash_t *hs, cfs_hash_bd_t *bd,