drbd: Disable activity log updates when the whole device is out of sync

When the complete device is marked as out of sync, we can disable
updates of the on disk AL. Currently AL updates are only disabled
if one uses the "invalidate-remote" command on an unconnected,
primary device, or when at attach time all bits in the bitmap are
set.

As of now, AL updated do not get disabled when a all bits becomes
set due to application writes to an unconnected DRBD device.
While this is a missing feature, it is not considered important,
and might get added later.

BTW, after initializing a "one legged" DRBD device
drbdadm create-md resX
drbdadm -- --force primary resX
AL updates also get disabled, until the first connect.

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

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 71c4c261573e..23878ffc43c8 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -963,6 +963,12 @@ static void set_ov_position(struct drbd_conf *mdev, enum drbd_conns cs)
         }
 }
 
+static void drbd_resume_al(struct drbd_conf *mdev)
+{
+        if (test_and_clear_bit(AL_SUSPENDED, &mdev->flags))
+                dev_info(DEV, "Resumed AL updates\n");
+}
+
 /**
  * __drbd_set_state() - Set a new DRBD state
  * @mdev:       DRBD device.
@@ -1160,6 +1166,10 @@ int __drbd_set_state(struct drbd_conf *mdev,
             ns.conn <= C_TEAR_DOWN && ns.conn >= C_TIMEOUT)
                 drbd_thread_restart_nowait(&mdev->receiver);
 
+        /* Resume AL writing if we get a connection */
+        if (os.conn < C_CONNECTED && ns.conn >= C_CONNECTED)
+                drbd_resume_al(mdev);
+
         ascw = kmalloc(sizeof(*ascw), GFP_ATOMIC);
         if (ascw) {
                 ascw->os = os;
@@ -2851,6 +2861,7 @@ void drbd_mdev_cleanup(struct drbd_conf *mdev)
         }
 
         drbd_free_resources(mdev);
+        clear_bit(AL_SUSPENDED, &mdev->flags);
 
         /*
          * currently we drbd_init_ee only on module load, so
@@ -3652,6 +3663,7 @@ int drbd_bmio_clear_n_write(struct drbd_conf *mdev)
 {
         int rv = -EIO;
 
+        drbd_resume_al(mdev);
         if (get_ldev_if_state(mdev, D_ATTACHING)) {
                 drbd_bm_clear_all(mdev);
                 rv = drbd_bm_write(mdev);