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-rw-r--r--drivers/md/dm-io-tracker.h81
1 files changed, 81 insertions, 0 deletions
diff --git a/drivers/md/dm-io-tracker.h b/drivers/md/dm-io-tracker.h
new file mode 100644
index 000000000..bdcc6273e
--- /dev/null
+++ b/drivers/md/dm-io-tracker.h
@@ -0,0 +1,81 @@
+/*
+ * 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 unsigned long dm_iot_idle_time(struct dm_io_tracker *iot)
+{
+ unsigned long r = 0;
+
+ spin_lock_irq(&iot->lock);
+ if (!iot->in_flight)
+ r = jiffies - iot->idle_time;
+ 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