[PATCH] FIX: Raid0 expansion cannot be restarted

[PATCH] FIX: Raid0 expansion cannot be restarted

[Adam Kwolek]

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 <adam.kwolek@intel.com>
---

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

diff --git a/Grow.c b/Grow.c
index d6ecde2..21531e0 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;

Re: [PATCH] FIX: Raid0 expansion cannot be restarted

[NeilBrown]

On Fri, 08 Apr 2011 12:05:45 +0200 Adam Kwolek <adam.kwolek@intel.com> wrote:

> 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 <adam.kwolek@intel.com>
> ---
> 
>  Grow.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/Grow.c b/Grow.c
> index d6ecde2..21531e0 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;

Thank,.
I changed this to simply remove that 'if' and 'return 1'.
There really is no way we should ever see level changes at this point - if we
think we do they are pending level changes for after a reshape so we don't
want to give them any special attention.

I have applied and pushed this out.

NeilBrown