diff options
Diffstat (limited to 'drivers/md/raid5.c')
| -rw-r--r-- | drivers/md/raid5.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 86ab6d14d782..ca968c3f25c7 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -3372,9 +3372,20 @@ static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s, BUG_ON(test_bit(R5_Wantcompute, &dev->flags)); BUG_ON(test_bit(R5_Wantread, &dev->flags)); BUG_ON(sh->batch_head); + + /* + * In the raid6 case if the only non-uptodate disk is P + * then we already trusted P to compute the other failed + * drives. It is safe to compute rather than re-read P. + * In other cases we only compute blocks from failed + * devices, otherwise check/repair might fail to detect + * a real inconsistency. + */ + if ((s->uptodate == disks - 1) && + ((sh->qd_idx >= 0 && sh->pd_idx == disk_idx) || (s->failed && (disk_idx == s->failed_num[0] || - disk_idx == s->failed_num[1]))) { + disk_idx == s->failed_num[1])))) { /* have disk failed, and we're requested to fetch it; * do compute it */ |