LU-6775 ldlm: reduce mem footprint of ldlm_resource

[fs/lustre-release.git] / lustre / ptlrpc / nodemap_member.c

diff --git a/lustre/ptlrpc/nodemap_member.c b/lustre/ptlrpc/nodemap_member.c
index a4e5063..1216fe7 100644 (file)
--- a/lustre/ptlrpc/nodemap_member.c
+++ b/lustre/ptlrpc/nodemap_member.c
@@ -47,7 +47,7 @@ void nm_member_putref(struct obd_export *exp)
 {
 }
 
-static __u32 nm_member_hashfn(cfs_hash_t *hash_body,
+static __u32 nm_member_hashfn(struct cfs_hash *hash_body,
                           const void *key, unsigned mask)
 {
        return hash_long((unsigned long)key, hash_body->hs_bkt_bits) & mask;
@@ -79,7 +79,7 @@ static void *nm_member_hs_hashobject(struct hlist_node *hnode)
                           exp_target_data.ted_nodemap_member);
 }
 
-static void nm_member_hs_get(cfs_hash_t *hs, struct hlist_node *hnode)
+static void nm_member_hs_get(struct cfs_hash *hs, struct hlist_node *hnode)
 {
        struct obd_export       *exp;
 
@@ -88,7 +88,7 @@ static void nm_member_hs_get(cfs_hash_t *hs, struct hlist_node *hnode)
        nm_member_getref(exp);
 }
 
-static void nm_member_hs_put_locked(cfs_hash_t *hs,
+static void nm_member_hs_put_locked(struct cfs_hash *hs,
                                 struct hlist_node *hnode)
 {
        struct obd_export       *exp;
@@ -116,7 +116,7 @@ void nm_member_del(struct lu_nodemap *nodemap, struct obd_export *exp)
        exp->exp_target_data.ted_nodemap = NULL;
 }
 
-static cfs_hash_ops_t nm_member_hash_operations = {
+static struct cfs_hash_ops nm_member_hash_operations = {
        .hs_hash        = nm_member_hashfn,
        .hs_key         = nm_member_hs_key,
        .hs_keycmp      = nm_member_hs_keycmp,
@@ -154,7 +154,7 @@ int nm_member_init_hash(struct lu_nodemap *nodemap)
 /**
  * Callback from deleting a hash member
  */
-static int nm_member_delete_hash_cb(cfs_hash_t *hs, cfs_hash_bd_t *bd,
+static int nm_member_delete_hash_cb(struct cfs_hash *hs, struct cfs_hash_bd *bd,
                                 struct hlist_node *hnode, void *data)
 {
        struct obd_export       *exp;
@@ -243,7 +243,7 @@ static void nm_member_exp_revoke(struct obd_export *exp)
        ldlm_revoke_export_locks(exp);
 }
 
-static int nm_member_reclassify_cb(cfs_hash_t *hs, cfs_hash_bd_t *bd,
+static int nm_member_reclassify_cb(struct cfs_hash *hs, struct cfs_hash_bd *bd,
                                   struct hlist_node *hnode, void *data)
 {
        struct obd_export       *exp;
@@ -272,14 +272,25 @@ 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
  */
@@ -293,8 +304,9 @@ void nm_member_reclassify_nodemap(struct lu_nodemap *nodemap)
        mutex_unlock(&reclassify_nodemap_lock);
 }
 
-static int nm_member_revoke_locks_cb(cfs_hash_t *hs, cfs_hash_bd_t *bd,
-                                    struct hlist_node *hnode, void *data)
+static int
+nm_member_revoke_locks_cb(struct cfs_hash *hs, struct cfs_hash_bd *bd,
+                         struct hlist_node *hnode, void *data)
 {
        struct obd_export       *exp;
        exp = hlist_entry(hnode, struct obd_export,