drbd: Hold a reference to ldev while doing meta-data IO

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/block/drbd/drbd_actlog.c b/drivers/block/drbd/drbd_actlog.c
index 528342c82ba1..3d7c2153daca 100644
--- a/drivers/block/drbd/drbd_actlog.c
+++ b/drivers/block/drbd/drbd_actlog.c
@@ -118,6 +118,12 @@ static int _drbd_md_sync_page_io(struct drbd_conf *mdev,
         bio->bi_end_io = drbd_md_io_complete;
         bio->bi_rw = rw;
 
+        if (!get_ldev_if_state(mdev, D_ATTACHING)) {  /* Corresponding put_ldev in drbd_md_io_complete() */
+                dev_err(DEV, "ASSERT FAILED: get_ldev_if_state() == 1 in _drbd_md_sync_page_io()\n");
+                ok = 0;
+                goto out;
+        }
+
         bio_get(bio); /* one bio_put() is in the completion handler */
         atomic_inc(&mdev->md_io_in_use); /* drbd_md_put_buffer() is in the completion handler */
         if (drbd_insert_fault(mdev, (rw & WRITE) ? DRBD_FAULT_MD_WR : DRBD_FAULT_MD_RD))