resolve race between obd_disconnect and class_disconnect_exports

Branch b1_8
b=19528
i=tappro
i=rread

diff --git a/lustre/ChangeLog b/lustre/ChangeLog
index 884de7b..88c7bdf 100644 (file)
--- a/lustre/ChangeLog
+++ b/lustre/ChangeLog
@@ -63,6 +63,12 @@ tbd Sun Microsystems, Inc.
          of Lustre filesystem with 4K stack may cause a stack overflow. For
          more information, please refer to bugzilla 17630.
 
+Severity   : normal
+Bugzilla   : 19528
+Description: resolve race between obd_disconnect and class_disconnect_exports
+Details    : if obd_disconnect will be called to already disconnected export he
+             forget release one reference and osc module can't unloaded.
+
 Severity   : enhancement
 Bugzilla   : 19293
 Description: move AT tunable parameters for more consistent usage

diff --git a/lustre/ldlm/ldlm_lib.c b/lustre/ldlm/ldlm_lib.c
index 158cf8f..100e0ec 100644 (file)
--- a/lustre/ldlm/ldlm_lib.c
+++ b/lustre/ldlm/ldlm_lib.c
@@ -464,12 +464,12 @@ int client_disconnect_export(struct obd_export *exp)
         if (!cli->cl_conn_count) {
                 CERROR("disconnecting disconnected device (%s)\n",
                        obd->obd_name);
-                GOTO(out_sem, rc = -EINVAL);
+                GOTO(out_disconnect, rc = -EINVAL);
         }
 
         cli->cl_conn_count--;
         if (cli->cl_conn_count)
-                GOTO(out_no_disconnect, rc = 0);
+                GOTO(out_disconnect, rc = 0);
 
         /* Mark import deactivated now, so we don't try to reconnect if any
          * of the cleanup RPCs fails (e.g. ldlm cancel, etc).  We don't
@@ -509,11 +509,14 @@ int client_disconnect_export(struct obd_export *exp)
         cli->cl_import = NULL;
 
         EXIT;
- out_no_disconnect:
+
+ out_disconnect:
+        /* use server style - class_disconnect should be always called for
+         * o_disconnect */
         err = class_disconnect(exp);
         if (!rc && err)
                 rc = err;
- out_sem:
+
         up_write(&cli->cl_sem);
         if (to_be_freed)
                 ldlm_namespace_free_post(to_be_freed);

diff --git a/lustre/obdclass/genops.c b/lustre/obdclass/genops.c
index fe78085..d291f40 100644 (file)
--- a/lustre/obdclass/genops.c
+++ b/lustre/obdclass/genops.c
@@ -940,10 +940,12 @@ int class_connect(struct lustre_handle *conn, struct obd_device *obd,
 }
 EXPORT_SYMBOL(class_connect);
 
-/* This function removes two references from the export: one for the
- * hash entry and one for the export pointer passed in.  The export
- * pointer passed to this function is destroyed should not be used
- * again. */
+/* This function removes 1-3 references from the export:
+ * 1 - for export pointer passed
+ * and if disconnect really need
+ * 2 - removing from hash
+ * 3 - in client_unlink_export
+ * The export pointer passed to this function can destroyed */
 int class_disconnect(struct obd_export *export)
 {
         int already_disconnected;
@@ -958,24 +960,27 @@ int class_disconnect(struct obd_export *export)
         spin_lock(&export->exp_lock);
         already_disconnected = export->exp_disconnected;
         export->exp_disconnected = 1;
-
-        if (!hlist_unhashed(&export->exp_nid_hash))
-                lustre_hash_del(export->exp_obd->obd_nid_hash,
-                                &export->exp_connection->c_peer.nid,
-                                &export->exp_nid_hash);
-
         spin_unlock(&export->exp_lock);
 
+
         /* class_cleanup(), abort_recovery(), and class_fail_export()
          * all end up in here, and if any of them race we shouldn't
          * call extra class_export_puts(). */
         if (already_disconnected)
-                RETURN(0);
+                GOTO(no_disconn, already_disconnected);
 
         CDEBUG(D_IOCTL, "disconnect: cookie "LPX64"\n",
                export->exp_handle.h_cookie);
 
+
+        if (!hlist_unhashed(&export->exp_nid_hash))
+                lustre_hash_del(export->exp_obd->obd_nid_hash,
+                                &export->exp_connection->c_peer.nid,
+                                &export->exp_nid_hash);
+
         class_unlink_export(export);
+
+no_disconn:
         class_export_put(export);
         RETURN(0);
 }
@@ -984,14 +989,14 @@ static void class_disconnect_export_list(struct list_head *list,
                                          enum obd_option flags)
 {
         int rc;
-        struct lustre_handle fake_conn;
-        struct obd_export *fake_exp, *exp;
+        struct obd_export *exp;
         ENTRY;
 
         /* It's possible that an export may disconnect itself, but
          * nothing else will be added to this list. */
         while (!list_empty(list)) {
                 exp = list_entry(list->next, struct obd_export, exp_obd_chain);
+                /* need for safe call CDEBUG after obd_disconnect */
                 class_export_get(exp);
 
                 spin_lock(&exp->exp_lock);
@@ -1010,22 +1015,14 @@ static void class_disconnect_export_list(struct list_head *list,
                         continue;
                 }
 
-                fake_conn.cookie = exp->exp_handle.h_cookie;
-                fake_exp = class_conn2export(&fake_conn);
-                if (!fake_exp) {
-                        class_export_put(exp);
-                        continue;
-                }
-
-                spin_lock(&fake_exp->exp_lock);
-                fake_exp->exp_flags = flags;
-                spin_unlock(&fake_exp->exp_lock);
-
+                class_export_get(exp);
                 CDEBUG(D_HA, "%s: disconnecting export at %s (%p), "
                        "last request at %ld\n",
                        exp->exp_obd->obd_name, obd_export_nid2str(exp),
                        exp, exp->exp_last_request_time);
-                rc = obd_disconnect(fake_exp);
+
+                /* release one export reference anyway */
+                rc = obd_disconnect(exp);
                 CDEBUG(D_HA, "disconnected export at %s (%p): rc %d\n",
                        obd_export_nid2str(exp), exp, rc);
                 class_export_put(exp);