dm io tracker: factor out IO tracker

Allow other code to use dm_io_tracker.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>

1 files changed, 69 insertions, 0 deletions

diff --git a/drivers/md/dm-io-tracker.h b/drivers/md/dm-io-tracker.h
new file mode 100644
index 000000000000..1dcf01f9f066
--- /dev/null
+++ b/drivers/md/dm-io-tracker.h
@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2021 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef DM_IO_TRACKER_H
+#define DM_IO_TRACKER_H
+
+#include <linux/jiffies.h>
+
+struct dm_io_tracker {
+	spinlock_t lock;
+
+	/*
+	 * Sectors of in-flight IO.
+	 */
+	sector_t in_flight;
+
+	/*
+	 * The time, in jiffies, when this device became idle
+	 * (if it is indeed idle).
+	 */
+	unsigned long idle_time;
+	unsigned long last_update_time;
+};
+
+static inline void dm_iot_init(struct dm_io_tracker *iot)
+{
+	spin_lock_init(&iot->lock);
+	iot->in_flight = 0ul;
+	iot->idle_time = 0ul;
+	iot->last_update_time = jiffies;
+}
+
+static inline bool dm_iot_idle_for(struct dm_io_tracker *iot, unsigned long j)
+{
+	bool r = false;
+
+	spin_lock_irq(&iot->lock);
+	if (!iot->in_flight)
+		r = time_after(jiffies, iot->idle_time + j);
+	spin_unlock_irq(&iot->lock);
+
+	return r;
+}
+
+static inline void dm_iot_io_begin(struct dm_io_tracker *iot, sector_t len)
+{
+	spin_lock_irq(&iot->lock);
+	iot->in_flight += len;
+	spin_unlock_irq(&iot->lock);
+}
+
+static inline void dm_iot_io_end(struct dm_io_tracker *iot, sector_t len)
+{
+	unsigned long flags;
+
+	if (!len)
+		return;
+
+	spin_lock_irqsave(&iot->lock, flags);
+	iot->in_flight -= len;
+	if (!iot->in_flight)
+		iot->idle_time = jiffies;
+	spin_unlock_irqrestore(&iot->lock, flags);
+}
+
+#endif