[PATCH 1/1] mdadm/Detail: Can't show container name correctly when unpluging disks

The test case is:
1. create one imsm container
2. create a raid5 device from the container
3. unplug two disks
4. mdadm --detail /dev/md126
[root@rhel85 ~]# mdadm -D /dev/md126
/dev/md126:
         Container : ��, member 0

The Detail function first gets container name by function
map_dev_preferred. Then it tries to find which disks are
available. In patch db5377883fef(It should be FAILED..)
uses map_dev_preferred to find which disks are under /dev.

But now, the major/minor information comes from kernel space.
map_dev_preferred malloc memory and init a device list when
first be called by Detail. It can't find the device in the
list by the major/minor. It free the memory and reinit the
list.

The container name now points to an area tha has been freed.
So the containt is a mess.

This patch replaces map_dev_preferred with devid2kname. If
the name is NULL, it means the disk is unplug.

Fixes: db5377883fef (It should be FAILED when raid has)
Signed-off-by: Xiao Ni <redacted>
Reported-by: Fine Fan <redacted>
---
 Detail.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/Detail.c b/Detail.c
index d3af0ab..2164de3 100644
--- a/Detail.c
+++ b/Detail.c

@@ -351,11 +351,13 @@ int Detail(char *dev, struct context *c)
 	avail = xcalloc(array.raid_disks, 1);
 
 	for (d = 0; d < array.raid_disks; d++) {
-		char *dv, *dv_rep;
-		dv = map_dev_preferred(disks[d*2].major,
-				disks[d*2].minor, 0, c->prefer);
-		dv_rep = map_dev_preferred(disks[d*2+1].major,
-				disks[d*2+1].minor, 0, c->prefer);
+		char *dv, *dv_rep = NULL;
+
+		if (!disks[d*2].major && !disks[d*2].minor)
+			continue;
+
+		dv = devid2kname(makedev(disks[d*2].major, disks[d*2].minor));
+		dv_rep = devid2kname(makedev(disks[d*2+1].major, disks[d*2+1].minor));
 
 		if ((dv && (disks[d*2].state & (1<<MD_DISK_SYNC))) ||
 		    (dv_rep && (disks[d*2+1].state & (1<<MD_DISK_SYNC)))) {

-- 
2.7.5