xfs: rework xlog_state_do_callback()

Clean it up a bit by factoring and rearranging some of the code.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

fs/xfs/xfs_log.c

@@ -2838,29 +2838,19 @@ xlog_state_iodone_process_iclog(
 	}
 }
 
-STATIC void
-xlog_state_do_callback(
+/*
+ * Loop over all the iclogs, running attached callbacks on them. Return true if
+ * we ran any callbacks, indicating that we dropped the icloglock.
+ */
+static bool
+xlog_state_do_iclog_callbacks(
 	struct xlog		*log)
+		__releases(&log->l_icloglock)
+		__acquires(&log->l_icloglock)
 {
-	struct xlog_in_core	*iclog;
-	struct xlog_in_core	*first_iclog;
-	bool			cycled_icloglock;
-	int			flushcnt = 0;
-	int			repeats = 0;
-
-	spin_lock(&log->l_icloglock);
-	do {
-		/*
-		 * Scan all iclogs starting with the one pointed to by the
-		 * log.  Reset this starting point each time the log is
-		 * unlocked (during callbacks).
-		 *
-		 * Keep looping through iclogs until one full pass is made
-		 * without running any callbacks.
-		 */
-		cycled_icloglock = false;
-		first_iclog = log->l_iclog;
-		iclog = first_iclog;
+	struct xlog_in_core	*first_iclog = log->l_iclog;
+	struct xlog_in_core	*iclog = first_iclog;
+	bool			ran_callback = false;
 
 	do {
 		LIST_HEAD(cb_list);
@@ -2879,7 +2869,7 @@ xlog_state_do_callback(
 		trace_xlog_iclog_callbacks_start(iclog, _RET_IP_);
 		xlog_cil_process_committed(&cb_list);
 		trace_xlog_iclog_callbacks_done(iclog, _RET_IP_);
-			cycled_icloglock = true;
+		ran_callback = true;
 
 		spin_lock(&log->l_icloglock);
 		if (xlog_is_shutdown(log))
@@ -2889,6 +2879,26 @@ xlog_state_do_callback(
 		iclog = iclog->ic_next;
 	} while (iclog != first_iclog);
 
+	return ran_callback;
+}
+
+
+/*
+ * Loop running iclog completion callbacks until there are no more iclogs in a
+ * state that can run callbacks.
+ */
+STATIC void
+xlog_state_do_callback(
+	struct xlog		*log)
+{
+	int			flushcnt = 0;
+	int			repeats = 0;
+
+	spin_lock(&log->l_icloglock);
+	while (xlog_state_do_iclog_callbacks(log)) {
+		if (xlog_is_shutdown(log))
+			break;
+
 		if (++repeats > 5000) {
 			flushcnt += repeats;
 			repeats = 0;
@@ -2896,7 +2906,7 @@ xlog_state_do_callback(
 				"%s: possible infinite loop (%d iterations)",
 				__func__, flushcnt);
 		}
-	} while (!xlog_is_shutdown(log) && cycled_icloglock);
+	}
 
 	if (log->l_iclog->ic_state == XLOG_STATE_ACTIVE ||
 	    xlog_is_shutdown(log))