md: Fix skipping recovery for read-only arrays.

commit 61e4947c99c4494336254ec540c50186d186150b upstream.

Since:
        commit 7ceb17e87bde79d285a8b988cfed9eaeebe60b86
        md: Allow devices to be re-added to a read-only array.

spares are activated on a read-only array. In case of raid1 and raid10
personalities it causes that not-in-sync devices are marked in-sync
without checking if recovery has been finished.

If a read-only array is degraded and one of its devices is not in-sync
(because the array has been only partially recovered) recovery will be skipped.

This patch adds checking if recovery has been finished before marking a device
in-sync for raid1 and raid10 personalities. In case of raid5 personality
such condition is already present (at raid5.c:6029).

Bug was introduced in 3.10 and causes data corruption.

Signed-off-by: Pawel Baldysiak <pawel.baldysiak@intel.com>
Signed-off-by: Lukasz Dorau <lukasz.dorau@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 2 insertions, 0 deletions

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 6f4824426e86..afaa5d425e9a 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1479,6 +1479,7 @@ static int raid1_spare_active(struct mddev *mddev)
                         }
                 }
                 if (rdev
+                    && rdev->recovery_offset == MaxSector
                     && !test_bit(Faulty, &rdev->flags)
                     && !test_and_set_bit(In_sync, &rdev->flags)) {
                         count++;
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 081bb3345353..0add86821755 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1762,6 +1762,7 @@ static int raid10_spare_active(struct mddev *mddev)
                         }
                         sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
                 } else if (tmp->rdev
+                           && tmp->rdev->recovery_offset == MaxSector
                            && !test_bit(Faulty, &tmp->rdev->flags)
                            && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
                         count++;