From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: [PATCH 1/5] md/raid1: be more cautious where we read-balance during resync. Date: Wed, 10 Sep 2014 16:20:44 +1000 Message-ID: <20140910062044.26400.79939.stgit@notabene.brown> References: <20140910062039.26400.36745.stgit@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140910062039.26400.36745.stgit@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: Eivind Sarto , Brassow Jonathan Cc: linux-raid@vger.kernel.org, majianpeng List-Id: linux-raid.ids 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 (v3.11+) 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 d7690f86fdb9..f66f67e5a423 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;