On Tuesday May 6, snitzer@xxxxxxxxx wrote:
>
> It looks like bitmap_update_sb()'s incrementing of events_cleared (on
> behalf of the local member) could be racing with the fact that the NBD
> member becomes faulty (whereby making the array degraded). This
> allows the events_cleared to reflect a clean->dirty transition last
> occurred before the array became degraded. My reasoning is: If it was
> a clean->dirty transition the bitmap still has the associated dirty
> bit set in the local member's bitmap, so using the bitmap to resync is
> valid.
>
> thanks,
> Mike
Thanks for persisting. I think I understand what is going on now.
How about this patch? It is similar to your, but instead of depending
on the odd/even state of the event counter, it directly checks the
clean/dirty state of the array.
NeilBrown
Signed-off-by: Neil Brown <neilb@xxxxxxx>
### Diffstat output
./drivers/md/md.c | 5 +++++
1 file changed, 5 insertions(+)
diff .prev/drivers/md/md.c ./drivers/md/md.c
--- .prev/drivers/md/md.c 2008-05-02 14:49:05.000000000 +1000
+++ ./drivers/md/md.c 2008-05-08 16:10:48.000000000 +1000
@@ -843,6 +843,8 @@ static int super_90_validate(mddev_t *md
/* if adding to array with a bitmap, then we can accept an
* older device ... but not too old.
*/
+ if (sb->state & (1<<MD_SB_CLEAN))
+ ev1++;
if (ev1 < mddev->bitmap->events_cleared)
return 0;
} else {
@@ -1218,6 +1220,9 @@ static int super_1_validate(mddev_t *mdd
/* If adding to array with a bitmap, then we can accept an
* older device, but not too old.
*/
+ if (mddev->recovery_cp == MaxSector)
+ /* array was clean, so can allow 'next' event */
+ ev1++;
if (ev1 < mddev->bitmap->events_cleared)
return 0;
} else {
--
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