md/raid1: clean up request counts properly in close_sync()

commit 669cc7ba77864e7b1ac39c9f2b2afb8730f341f4 upstream.

If there are outstanding writes when close_sync is called,
the change to ->start_next_window might cause them to
decrement the wrong counter when they complete.  Fix this
by merging the two counters into the one that will be decremented.

Having an incorrect value in a counter can cause raise_barrier()
to hangs, so this is suitable for -stable.

Fixes: 79ef3a8aa1cb1523cc231c9a90a278333c21f761
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index d7690f86fdb9a6202edfa6d8fa5f95517fe8e75b..3aa305f5a9af00e4a172d0b1f22c209f12cb6987 100644 (file)
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1548,8 +1548,13 @@ static void close_sync(struct r1conf *conf)
        mempool_destroy(conf->r1buf_pool);
        conf->r1buf_pool = NULL;
 
+       spin_lock_irq(&conf->resync_lock);
        conf->next_resync = 0;
        conf->start_next_window = MaxSector;
+       conf->current_window_requests +=
+               conf->next_window_requests;
+       conf->next_window_requests = 0;
+       spin_unlock_irq(&conf->resync_lock);
 }
 
 static int raid1_spare_active(struct mddev *mddev)