1 files changed, 96 insertions, 0 deletions
diff --git a/fs/xfs/xfs_drain.c b/fs/xfs/xfs_drain.c
new file mode 100644
index 000000000000..e8fced914f88
--- /dev/null
+++ b/fs/xfs/xfs_drain.c
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2022 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_ag.h"
+#include "xfs_trace.h"
+
+void
+xfs_drain_init(
+	struct xfs_drain	*dr)
+{
+	atomic_set(&dr->dr_count, 0);
+	init_waitqueue_head(&dr->dr_waiters);
+}
+
+void
+xfs_drain_free(struct xfs_drain	*dr)
+{
+	ASSERT(atomic_read(&dr->dr_count) == 0);
+}
+
+/* Increase the pending intent count. */
+static inline void xfs_drain_bump(struct xfs_drain *dr)
+{
+	atomic_inc(&dr->dr_count);
+}
+
+/* Decrease the pending intent count, and wake any waiters, if appropriate. */
+static inline void xfs_drain_drop(struct xfs_drain *dr)
+{
+	if (atomic_dec_and_test(&dr->dr_count) &&
+	    wq_has_sleeper(&dr->dr_waiters))
+		wake_up(&dr->dr_waiters);
+}
+
+/* Are there work items pending? */
+static inline bool xfs_drain_busy(struct xfs_drain *dr)
+{
+	return atomic_read(&dr->dr_count) > 0;
+}
+
+/*
+ * Wait for the pending intent count for a drain to hit zero.
+ *
+ * Callers must not hold any locks that would prevent intents from being
+ * finished.
+ */
+static inline int xfs_drain_wait(struct xfs_drain *dr)
+{
+	return wait_event_killable(dr->dr_waiters, !xfs_drain_busy(dr));
+}
+
+/* Add an item to the pending count. */
+void
+xfs_perag_bump_intents(
+	struct xfs_perag	*pag)
+{
+	trace_xfs_perag_bump_intents(pag, __return_address);
+	xfs_drain_bump(&pag->pag_intents);
+}
+
+/* Remove an item from the pending count. */
+void
+xfs_perag_drop_intents(
+	struct xfs_perag	*pag)
+{
+	trace_xfs_perag_drop_intents(pag, __return_address);
+	xfs_drain_drop(&pag->pag_intents);
+}
+
+/*
+ * Wait for the pending intent count for AG metadata to hit zero.
+ * Callers must not hold any AG header buffers.
+ */
+int
+xfs_perag_drain_intents(
+	struct xfs_perag	*pag)
+{
+	trace_xfs_perag_wait_intents(pag, __return_address);
+	return xfs_drain_wait(&pag->pag_intents);
+}
+
+/* Might someone else be processing intents for this AG? */
+bool
+xfs_perag_intents_busy(
+	struct xfs_perag	*pag)
+{
+	return xfs_drain_busy(&pag->pag_intents);
+}