1 files changed, 15 insertions, 0 deletions
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 82b2195efaca..3611b230d0aa 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -397,6 +397,21 @@ struct dm_target {
 	 * bio_set_dev(). NOTE: ideally a target should _not_ need this.
 	 */
 	bool needs_bio_set_dev:1;
+
+	/*
+	 * Set if the target supports flush optimization. If all the targets in
+	 * a table have flush_bypasses_map set, the dm core will not send
+	 * flushes to the targets via a ->map method. It will iterate over
+	 * dm_table->devices and send flushes to the devices directly. This
+	 * optimization reduces the number of flushes being sent when multiple
+	 * targets in a table use the same underlying device.
+	 *
+	 * This optimization may be enabled on targets that just pass the
+	 * flushes to the underlying devices without performing any other
+	 * actions on the flush request. Currently, dm-linear and dm-stripe
+	 * support it.
+	 */
+	bool flush_bypasses_map:1;
 };
 
 void *dm_per_bio_data(struct bio *bio, size_t data_size);