md/raid10: avoid fullsync when not necessary.

This is the raid10 equivalent of

commit 4f0a5e012cf41321d611e7cad63e1017d143d138
    MD RAID1: Further conditionalize 'fullsync'

If a device in a newly assembled array is not fully recovered we
currently do a fully resync by don't need to.

Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 06eeb99ea6fc..8d39d63281b9 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3747,7 +3747,8 @@ static int run(struct mddev *mddev)
                     !test_bit(In_sync, &disk->rdev->flags)) {
                         disk->head_position = 0;
                         mddev->degraded++;
-                        if (disk->rdev)
+                        if (disk->rdev &&
+                            disk->rdev->saved_raid_disk < 0)
                                 conf->fullsync = 1;
                 }
                 disk->recovery_disabled = mddev->recovery_disabled - 1;