md: make sure metadata is updated when spares are activated or removed.

commit 6dafab6b1383e912cd252fa809570b484eb6e0dc upstream.

It isn't always necessary to update the metadata when spares are
removed as the presence-or-not of a spare isn't really important to
the integrity of an array.
Also activating a spare doesn't always require updating the metadata
as the update on 'recovery-completed' is usually sufficient.

However the introduction of 'replacement' devices have made these
transitions sometimes more important.  For example the 'Replacement'
flag isn't cleared until the original device is removed, so we need
to ensure a metadata update after that 'spare' is removed.

So set MD_CHANGE_DEVS whenever a spare is activated or removed, to
complement the current situation where it is set when a spare is added
or a device is failed (or a number of other less common situations).

This is suitable for -stable as out-of-data metadata could lead
to data corruption.
This is only relevant for 3.3 and later 9when 'replacement' as
introduced.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 52cfeb21f568da393170cd7b9685328345ff50ea..6fc0c26ecb763cea08bd04078e9bab0e2bb14242 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -7672,6 +7672,8 @@ static int remove_and_add_spares(struct mddev *mddev)
                        }
                }
        }
+       if (removed)
+               set_bit(MD_CHANGE_DEVS, &mddev->flags);
        return spares;
 }
 
@@ -7685,9 +7687,11 @@ static void reap_sync_thread(struct mddev *mddev)
            !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
                /* success...*/
                /* activate any spares */
-               if (mddev->pers->spare_active(mddev))
+               if (mddev->pers->spare_active(mddev)) {
                        sysfs_notify(&mddev->kobj, NULL,
                                     "degraded");
+                       set_bit(MD_CHANGE_DEVS, &mddev->flags);
+               }
        }
        if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
            mddev->pers->finish_reshape)