xfs: ensure that sync updates the log tail correctly
[linux-2.6.git] / fs / xfs / xfs_log.c
index e8fba92..2be0191 100644 (file)
@@ -745,9 +745,16 @@ xfs_log_move_tail(xfs_mount_t      *mp,
 
 /*
  * Determine if we have a transaction that has gone to disk
- * that needs to be covered. Log activity needs to be idle (no AIL and
- * nothing in the iclogs). And, we need to be in the right state indicating
- * something has gone out.
+ * that needs to be covered. To begin the transition to the idle state
+ * firstly the log needs to be idle (no AIL and nothing in the iclogs).
+ * If we are then in a state where covering is needed, the caller is informed
+ * that dummy transactions are required to move the log into the idle state.
+ *
+ * Because this is called as part of the sync process, we should also indicate
+ * that dummy transactions should be issued in anything but the covered or
+ * idle states. This ensures that the log tail is accurately reflected in
+ * the log at the end of the sync, hence if a crash occurrs avoids replay
+ * of transactions where the metadata is already on disk.
  */
 int
 xfs_log_need_covered(xfs_mount_t *mp)
@@ -759,17 +766,24 @@ xfs_log_need_covered(xfs_mount_t *mp)
                return 0;
 
        spin_lock(&log->l_icloglock);
-       if (((log->l_covered_state == XLOG_STATE_COVER_NEED) ||
-               (log->l_covered_state == XLOG_STATE_COVER_NEED2))
-                       && !xfs_trans_ail_tail(log->l_ailp)
-                       && xlog_iclogs_empty(log)) {
-               if (log->l_covered_state == XLOG_STATE_COVER_NEED)
-                       log->l_covered_state = XLOG_STATE_COVER_DONE;
-               else {
-                       ASSERT(log->l_covered_state == XLOG_STATE_COVER_NEED2);
-                       log->l_covered_state = XLOG_STATE_COVER_DONE2;
+       switch (log->l_covered_state) {
+       case XLOG_STATE_COVER_DONE:
+       case XLOG_STATE_COVER_DONE2:
+       case XLOG_STATE_COVER_IDLE:
+               break;
+       case XLOG_STATE_COVER_NEED:
+       case XLOG_STATE_COVER_NEED2:
+               if (!xfs_trans_ail_tail(log->l_ailp) &&
+                   xlog_iclogs_empty(log)) {
+                       if (log->l_covered_state == XLOG_STATE_COVER_NEED)
+                               log->l_covered_state = XLOG_STATE_COVER_DONE;
+                       else
+                               log->l_covered_state = XLOG_STATE_COVER_DONE2;
                }
+               /* FALLTHRU */
+       default:
                needed = 1;
+               break;
        }
        spin_unlock(&log->l_icloglock);
        return needed;