Re: [PATCH v3] mdadm/Detail: show correct state for cluster-md array

After kernel md module commit 480523feae581, in md-cluster env,
mddev->in_sync always zero, it will make array.state never set
up MD_SB_CLEAN. it causes "mdadm -D /dev/mdX" show state 'active'
all the time.

bitmap.c: add a new API IsBitmapDirty() to support inquiry bitmap
dirty or clean.

Signed-off-by: Zhao Heming <redacted>
---
v3:
- Detail.c: fix error logic: v2 code didn't check bitmap when dv is null.
v2:
- Detail.c: change to read only one device.
- bitmap.c: modify IsBitmapDirty() to check all bitmap on the selected device.

---
 Detail.c | 20 +++++++++++++++++++-
 bitmap.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 mdadm.h  |  1 +
 3 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/Detail.c b/Detail.c
index 24eeba0..a69e5ac 100644
--- a/Detail.c
+++ b/Detail.c

@@ -495,8 +495,26 @@ int Detail(char *dev, struct context *c)
 							  sra->array_state);
 				else
 					arrayst = "clean";
-			} else
+			} else {
 				arrayst = "active";
+				if (array.state & (1<<MD_SB_CLUSTERED)) {
+					for (d = 0; d < max_disks * 2; d++) {
+						char *dv;
+						mdu_disk_info_t disk = disks[d];
+
+						if (d >= array.raid_disks * 2 &&
+							disk.major == 0 && disk.minor == 0)
+							continue;
+						if ((d & 1) && disk.major == 0 && disk.minor == 0)
+							continue;
+						dv = map_dev_preferred(disk.major, disk.minor, 0,
+												c->prefer);
+						if (!dv) continue;