dm: allow targets to request flushes regardless of underlying device support

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 <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 8bdbbfce759..bdd65e97a12 100644
--- a/include/linux/device-mapper.h
+++ b/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.
 	 */