[PATCH] FIX: Raid0 expansion cannot be restarted (v2)

When raid0 expansion is restarted, mdadm refuses to correctly assemble
array because critical section cannot be restored from backup file.
mdadm exits with information:
mdadm: Failed to restore critical section for reshape - sorry.

For raid0 new level is 0, current array level is 4.
Function Grow_restart() doesn't allow for level change.
It should be allowed for raid0, while raid4 is reshape mid-point only.
'Native' raid0 reshape is not possible, because md doesn't support it.

Signed-off-by: Adam Kwolek
---

Grow.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/Grow.c b/Grow.c
index d6ecde2..53d0a68 100644
--- a/Grow.c
+++ b/Grow.c
@@ -3102,7 +3102,8 @@ int Grow_restart(struct supertype *st, struct mdinfo *info, int *fdlist, int cnt
unsigned long long nstripe, ostripe;
int ndata, odata;

- if (info->new_level != info->array.level)
+ if ((info->new_level != info->array.level) &&
+ !((info->new_level == 0) && (info->array.level == 4)))
return 1; /* Cannot handle level changes (they are instantaneous) */

odata = info->array.raid_disks - info->delta_disks - 1;

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