[MD PATCH 1/1] Raid5 should update rdev->sectors after reshape

[Xiao Ni <xni@redhat.com>]

The raid5 md device is created by the disks which we don't use the total size. For example,
the size of the device is 5G and it just uses 3G of the devices to create one raid5 device.
Then change the chunksize and wait reshape to finish. After reshape finishing stop the raid
and assemble it again. It fails.
mdadm -CR /dev/md0 -l5 -n3 /dev/loop[0-2] --size=3G --chunk=32 --assume-clean
mdadm /dev/md0 --grow --chunk=64
wait reshape to finish
mdadm -S /dev/md0
mdadm -As
The error messages:
[197519.814302] md: loop1 does not have a valid v1.2 superblock, not importing!
[197519.821686] md: md_import_device returned -22

After reshape the data offset is changed. It selects backwards direction in this condition.
In function super_1_load it compares the available space of the underlying device with
sb->data_size. The new data offset gets bigger after reshape. So super_1_load returns -EINVAL.
sb->data_size is updated in md_finish_reshape. So add md_finish_reshape in end_reshape.

Signed-off-by: Xiao Ni <xni@redhat.com>
---
 drivers/md/raid5.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index ec0f951..e7f527c 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7947,12 +7947,10 @@ static void end_reshape(struct r5conf *conf)
 {
 
 	if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
-		struct md_rdev *rdev;
 
 		spin_lock_irq(&conf->device_lock);
 		conf->previous_raid_disks = conf->raid_disks;
-		rdev_for_each(rdev, conf->mddev)
-			rdev->data_offset = rdev->new_data_offset;
+		md_finish_reshape(conf->mddev);
 		smp_wmb();
 		conf->reshape_progress = MaxSector;
 		conf->mddev->reshape_position = MaxSector;
-- 
2.7.4