From: Joe Thornber <[email-masked]>

Allow targets to override the 'supports flush' calculation.

Set 'flush_supported' if a target needs to receive flushes regardless of
whether or not its underlying devices have support.

Signed-off-by: Joe Thornber <[email-masked]>
Signed-off-by: Mike Snitzer <[email-masked]>
Signed-off-by: Alasdair G Kergon <[email-masked]>

---
 drivers/md/dm-table.c         |    3 +++
 include/linux/device-mapper.h |    6 ++++++
 2 files changed, 9 insertions(+)

Index: linux/drivers/md/dm-table.c
===================================================================
--- linux.orig/drivers/md/dm-table.c
+++ linux/drivers/md/dm-table.c
@@ -1319,6 +1319,9 @@ static bool dm_table_supports_flush(stru
 		if (!ti->num_flush_requests)
 			continue;
 
+		if (ti->flush_supported)
+			return 1;
+
 		if (ti->type->iterate_devices &&
 		    ti->type->iterate_devices(ti, device_flush_capable, &flush))
 			return 1;
Index: linux/include/linux/device-mapper.h
===================================================================
--- linux.orig/include/linux/device-mapper.h
+++ linux/include/linux/device-mapper.h
@@ -212,6 +212,12 @@ struct dm_target {
 	char *error;
 
 	/*
+	 * Set if this target needs to receive flushes regardless of
+	 * whether or not its underlying devices have support.
+	 */
+	bool flush_supported:1;
+
+	/*
 	 * Set if this target needs to receive discards regardless of
 	 * whether or not its underlying devices have support.
 	 */