Patch "Raid5 should update rdev->sectors after reshape" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

    Raid5 should update rdev->sectors after reshape

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
raid5-should-update-rdev-sectors-after-reshape.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Xiao Ni <[email protected]>
Date: Wed, 5 Jul 2017 17:34:04 +0800
Subject: Raid5 should update rdev->sectors after reshape

From: Xiao Ni <[email protected]>

commit b5d27718f38843a74552e9a93d32e2391fd3999f upstream.

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. rdev->sectors is updated in md_finish_reshape. Then sb->data_size is set in super_1_sync based on rdev->sectors. So add md_finish_reshape in end_reshape.

---
 drivers/md/raid5.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

@@ -7560,12 +7560,10 @@ static void end_reshape(struct r5conf *c
 {
 
 	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;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/raid5-should-update-rdev-sectors-after-reshape.patch