Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933309AbbHXJSl (ORCPT ); Mon, 24 Aug 2015 05:18:41 -0400 Received: from mx2.suse.de ([195.135.220.15]:58318 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932801AbbHXJKM (ORCPT ); Mon, 24 Aug 2015 05:10:12 -0400 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, NeilBrown , Jiri Slaby Subject: [PATCH 3.12 56/82] md/raid1: extend spinlock to protect raid1_end_read_request against inconsistencies Date: Mon, 24 Aug 2015 11:09:16 +0200 Message-Id: <17f52b4a5b8c7995396ed1d0dc7155a31a61dd00.1440407339.git.jslaby@suse.cz> X-Mailer: git-send-email 2.5.0 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3007 Lines: 84 From: NeilBrown 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 423f04d63cf421ea436bcc5be02543d549ce4b28 upstream. raid1_end_read_request() assumes that the In_sync bits are consistent with the ->degaded count. raid1_spare_active updates the In_sync bit before the ->degraded count and so exposes an inconsistency, as does error() So extend the spinlock in raid1_spare_active() and error() to hide those inconsistencies. This should probably be part of Commit: 34cab6f42003 ("md/raid1: fix test for 'was read error from last working device'.") as it addresses the same issue. It fixes the same bug and should go to -stable for same reasons. Fixes: 76073054c95b ("md/raid1: clean up read_balance.") Signed-off-by: NeilBrown Signed-off-by: Jiri Slaby --- drivers/md/raid1.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 14934ac112c3..1cb7642c1ba9 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -1382,6 +1382,7 @@ static void error(struct mddev *mddev, struct md_rdev *rdev) { char b[BDEVNAME_SIZE]; struct r1conf *conf = mddev->private; + unsigned long flags; /* * If it is not operational, then we have already marked it as dead @@ -1401,14 +1402,13 @@ static void error(struct mddev *mddev, struct md_rdev *rdev) return; } set_bit(Blocked, &rdev->flags); + spin_lock_irqsave(&conf->device_lock, flags); if (test_and_clear_bit(In_sync, &rdev->flags)) { - unsigned long flags; - spin_lock_irqsave(&conf->device_lock, flags); mddev->degraded++; set_bit(Faulty, &rdev->flags); - spin_unlock_irqrestore(&conf->device_lock, flags); } else set_bit(Faulty, &rdev->flags); + spin_unlock_irqrestore(&conf->device_lock, flags); /* * if recovery is running, make sure it aborts. */ @@ -1466,7 +1466,10 @@ static int raid1_spare_active(struct mddev *mddev) * Find all failed disks within the RAID1 configuration * and mark them readable. * Called under mddev lock, so rcu protection not needed. + * device_lock used to avoid races with raid1_end_read_request + * which expects 'In_sync' flags and ->degraded to be consistent. */ + spin_lock_irqsave(&conf->device_lock, flags); for (i = 0; i < conf->raid_disks; i++) { struct md_rdev *rdev = conf->mirrors[i].rdev; struct md_rdev *repl = conf->mirrors[conf->raid_disks + i].rdev; @@ -1496,7 +1499,6 @@ static int raid1_spare_active(struct mddev *mddev) sysfs_notify_dirent_safe(rdev->sysfs_state); } } - spin_lock_irqsave(&conf->device_lock, flags); mddev->degraded -= count; spin_unlock_irqrestore(&conf->device_lock, flags); -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/