From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: NeilBrown , Kamal Mostafa Subject: [PATCH 3.13 130/163] md/raid1: be more cautious where we read-balance during resync. Date: Thu, 9 Oct 2014 14:02:35 -0700 Message-Id: <1412888588-26755-131-git-send-email-kamal@canonical.com> In-Reply-To: <1412888588-26755-1-git-send-email-kamal@canonical.com> References: <1412888588-26755-1-git-send-email-kamal@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.13.11.9 -stable review patch. If anyone has any objections, please let me know. ------------------ From: NeilBrown commit c6d119cf1b5a778e9ed60a006e2a434fcc4471a2 upstream. 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 Signed-off-by: NeilBrown Signed-off-by: Kamal Mostafa --- 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 b806da4..e124f01 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -542,11 +542,7 @@ 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; -- 1.9.1