On Wed, 09 Mar 2011 14:46:02 +0100 Adam Kwolek <adam.kwolek@xxxxxxxxx> wrote:
> Smaller checkpoint can be stored when metadata is not in migration state
> (this means when there is no second map).
> Without this additional condition it can occur that during array start/stop
> sequence checkpoint was roll back to 0.
>
> Signed-off-by: Adam Kwolek <adam.kwolek@xxxxxxxxx>
> ---
>
> super-intel.c | 12 +++++++++---
> 1 files changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/super-intel.c b/super-intel.c
> index cd409e9..4e3de8a 100644
> --- a/super-intel.c
> +++ b/super-intel.c
> @@ -5335,9 +5335,15 @@ mark_checkpoint:
> */
> if (units32 == units &&
> __le32_to_cpu(dev->vol.curr_migr_unit) != units32) {
> - dprintf("imsm: mark checkpoint (%u)\n", units32);
> - dev->vol.curr_migr_unit = __cpu_to_le32(units32);
> - super->updates_pending++;
> + struct imsm_map *map2 = get_imsm_map(dev, 1);
> + if ((__le32_to_cpu(dev->vol.curr_migr_unit) < units32)
> + || (map2 == NULL)) {
> + dprintf("imsm: mark checkpoint (%u)\n",
> + units32);
> + dev->vol.curr_migr_unit =
> + __cpu_to_le32(units32);
> + super->updates_pending++;
> + }
> }
> }
>
>
Not applied.
I don't really understand the change you are making here.
As it seems to me that:
- before the patch, we only update the 'curr_migr_unit' when
units32 is different
- after the patch, we only update it if units32 is bigger, or if
map2==NULL (meaning this isn't a migration?).
So when would units32 be smaller?? What is the important case that this
fixes?
>From the comment, it seems to be to avoid 'roll back to 0'. I don't see
how it does that, and I don't see why that is a problem.
If some reshape has happened but curr_migr_unit is 0, that just means
that we need to replay the backed-up data and set curr_migr_unit
accordingly (or reflect that the backed-up data has been migrated).
So after Grow_restart has run, curr_migr_unit should never be zero.
You will need to get update_super_imsm to understand '_reshape_progress'
for this to work properly.
NeilBrown
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