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)
*/
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 = {
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 */
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,