[RFC PATCH v13 12/20] dm verity: set DM_TARGET_SINGLETON feature flag

[Fan Wu]

The device-mapper has a flag to mark targets as singleton, which is a
required flag for immutable targets. Without this flag, multiple
dm-verity targets can be added to a mapped device, which has no
practical use cases. Also from dm_table_get_immutable_target(),
it documented that "Immutable target is implicitly a singleton".

This patch adds the missing flag, restricting only one
dm-verity target per mapped device.

Signed-off-by: Fan Wu <wufan at linux.microsoft.com>

---
v1-v10:
  + Not present

v11:
  + Introduced

v12:
  + No changes

v13:
  + No changes
---
 drivers/md/dm-verity-target.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index 1b591bfa90d5..a99ef30e45ca 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -1559,7 +1559,7 @@ int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned i
 
 static struct target_type verity_target = {
 	.name		= "verity",
-	.features	= DM_TARGET_IMMUTABLE,
+	.features	= DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
 	.version	= {1, 10, 0},
 	.module		= THIS_MODULE,
 	.ctr		= verity_ctr,
-- 
2.43.1