This case tries to allow raid5 reshape to use backwards direction.
It changes chunksize after reshape and stops the raid. Then starts
the raid again.

Signed-off-by: Xiao Ni <redacted>
Suggested-by:  Jes Sorensen <jes.sorensen@gmail.com>
Suggested-by:  Zhilong Liu <redacted>
Suggested-by:  Paul Menzel <redacted>
---
  test           |  7 +++++++
  tests/02r5grow | 17 +++++++++++++++++
  2 files changed, 24 insertions(+)

diff --git a/test b/test
index 87e2df2..98e2981 100755
--- a/test
+++ b/test

@@ -320,6 +320,13 @@ check() {
  		grep -sq "inactive" /proc/mdstat ||
  			die "array is not inactive!"
  		;;
+	# It only can be used when there is only one raid
+	chunk )
+		chunk_size=`awk -F',' '/chunk/{print $2}' /proc/mdstat | awk -F'[a-z]' '{print $1}'`
+		if [ "$chunk_size" -ne "$2" ] ; then
+			die "chunksize should be $2, but it's $chunk_size"
+		fi
+		;;
  	* )
  		die "unknown check $1"
  		;;

diff --git a/tests/02r5grow b/tests/02r5grow
index 386e82e..ea3101b 100644
--- a/tests/02r5grow
+++ b/tests/02r5grow

@@ -34,3 +34,20 @@ check nosync
  sh tests/testdev $md0 3 $[size/2] 128
  
  mdadm -S $md0
+
+# create a raid5 array and change the chunk
+mdadm -CR $md0 --level raid5 --metadata=1.1 --chunk=32 --raid-disks 3 --size $[size/2] $dev1 $dev2 $dev3
+check wait
+check state UUU
+check chunk 32
+
+mdadm $md0 --grow --chunk=64
+check reshape
+check wait
+check chunk 64
+
+mdadm -S $md0
+mdadm -As
+check state UUU
+check chunk 64
+mdadm -Ss