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Subject[patch 08/47] md: Ensure interrupted recovery completed properly (v1 metadata plus bitmap)
2.6.25-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: Neil Brown <neilb@notabene.brown>
commit 8c2e870a625bd336b2e7a65a97c1836acef07322 upstream

If, while assembling an array, we find a device which is not fully
in-sync with the array, it is important to set the "fullsync" flags.
This is an exact analog to the setting of this flag in hot_add_disk
methods.

Currently, only v1.x metadata supports having devices in an array
which are not fully in-sync (it keep track of how in sync they are).
The 'fullsync' flag only makes a difference when a write-intent bitmap
is being used. In this case it tells recovery to ignore the bitmap
and recovery all blocks.

This fix is already in place for raid1, but not raid5/6 or raid10.

So without this fix, a raid1 ir raid4/5/6 array with version 1.x
metadata and a write intent bitmaps, that is stopped in the middle
of a recovery, will appear to complete the recovery instantly
after it is reassembled, but the recovery will not be correct.

If you might have an array like that, issueing
echo repair > /sys/block/mdXX/md/sync_action
will make sure recovery completes properly.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/md/raid10.c | 2 ++
drivers/md/raid5.c | 4 +++-
2 files changed, 5 insertions(+), 1 deletion(-)
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2102,6 +2102,8 @@ static int run(mddev_t *mddev)
!test_bit(In_sync, &disk->rdev->flags)) {
disk->head_position = 0;
mddev->degraded++;
+ if (disk->rdev)
+ conf->fullsync = 1;
}
}

--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4166,7 +4166,9 @@ static int run(mddev_t *mddev)
" disk %d\n", bdevname(rdev->bdev,b),
raid_disk);
working_disks++;
- }
+ } else
+ /* Cannot rely on bitmap to complete recovery */
+ conf->fullsync = 1;
}

/*
--


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