From c6d119cf1b5a778e9ed60a006e2a434fcc4471a2 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 9 Sep 2014 13:49:46 +1000 Subject: [PATCH] md/raid1: be more cautious where we read-balance during resync. commit 79ef3a8aa1cb1523cc231c9a90a278333c21f761 made it possible for reads to happen concurrently with resync. This means that we need to be more careful where read_balancing is allowed during resync - we can no longer be sure that any resync that has already started will definitely finish. So keep read_balancing to before recovery_cp, which is conservative but safe. This bug makes it possible to read from a device that doesn't have up-to-date data, so it can cause data corruption. So it is suitable for any kernel since 3.11. Fixes: 79ef3a8aa1cb1523cc231c9a90a278333c21f761 cc: stable@vger.kernel.org (v3.13+) Signed-off-by: NeilBrown --- drivers/md/raid1.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 9ebccf624571..ad0468c42d23 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -540,11 +540,7 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect has_nonrot_disk = 0; choose_next_idle = 0; - if (conf->mddev->recovery_cp < MaxSector && - (this_sector + sectors >= conf->next_resync)) - choose_first = 1; - else - choose_first = 0; + choose_first = (conf->mddev->recovery_cp < this_sector + sectors); for (disk = 0 ; disk < conf->raid_disks * 2 ; disk++) { sector_t dist; -- GitLab