drbd: describe bitmap locking for bulk operation in finer detail

Now that we do no longer in-place endian-swap the bitmap, we allow
selected bitmap operations (testing bits, sometimes even settting bits)
during some bulk operations.

This caused us to hit a lot of FIXME asserts similar to
	FIXME asender in drbd_bm_count_bits,
	bitmap locked for 'write from resync_finished' by worker
Which now is nonsense: looking at the bitmap is perfectly legal
as long as it is not being resized.

This cosmetic patch defines some flags to describe expectations in finer
detail, so the asserts in e.g. bm_change_bits_to() can be skipped if
appropriate.

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

1 files changed, 12 insertions, 5 deletions

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index e5686a81f42c..e13134f83fae 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -2599,7 +2599,8 @@ static enum drbd_conns drbd_sync_handshake(struct drbd_conf *mdev, enum drbd_rol
 
 	if (abs(hg) >= 2) {
 		dev_info(DEV, "Writing the whole bitmap, full sync required after drbd_sync_handshake.\n");
-		if (drbd_bitmap_io(mdev, &drbd_bmio_set_n_write, "set_n_write from sync_handshake"))
+		if (drbd_bitmap_io(mdev, &drbd_bmio_set_n_write, "set_n_write from sync_handshake",
+					BM_LOCKED_SET_ALLOWED))
 			return C_MASK;
 	}
 
@@ -3053,7 +3054,8 @@ static int receive_uuids(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 		if (skip_initial_sync) {
 			dev_info(DEV, "Accepted new current UUID, preparing to skip initial sync\n");
 			drbd_bitmap_io(mdev, &drbd_bmio_clear_n_write,
-					"clear_n_write from receive_uuids");
+					"clear_n_write from receive_uuids",
+					BM_LOCKED_TEST_ALLOWED);
 			_drbd_uuid_set(mdev, UI_CURRENT, p_uuid[UI_CURRENT]);
 			_drbd_uuid_set(mdev, UI_BITMAP, 0);
 			_drbd_set_state(_NS2(mdev, disk, D_UP_TO_DATE, pdsk, D_UP_TO_DATE),
@@ -3494,7 +3496,9 @@ static int receive_bitmap(struct drbd_conf *mdev, enum drbd_packets cmd, unsigne
 	int ok = false;
 	struct p_header80 *h = &mdev->data.rbuf.header.h80;
 
-	/* drbd_bm_lock(mdev, "receive bitmap"); By intention no bm_lock */
+	drbd_bm_lock(mdev, "receive bitmap", BM_LOCKED_SET_ALLOWED);
+	/* you are supposed to send additional out-of-sync information
+	 * if you actually set bits during this phase */
 
 	/* maybe we should use some per thread scratch page,
 	 * and allocate that during initial device creation? */
@@ -3568,7 +3572,7 @@ static int receive_bitmap(struct drbd_conf *mdev, enum drbd_packets cmd, unsigne
 
 	ok = true;
  out:
-	/* drbd_bm_unlock(mdev); by intention no lock */
+	drbd_bm_unlock(mdev);
 	if (ok && mdev->state.conn == C_WF_BITMAP_S)
 		drbd_start_resync(mdev, C_SYNC_SOURCE);
 	free_page((unsigned long) buffer);
@@ -3817,7 +3821,6 @@ static void drbd_disconnect(struct drbd_conf *mdev)
 
 	fp = FP_DONT_CARE;
 	if (get_ldev(mdev)) {
-		drbd_bitmap_io(mdev, &drbd_bm_write, "write from disconnect");
 		fp = mdev->ldev->dc.fencing;
 		put_ldev(mdev);
 	}
@@ -3846,6 +3849,10 @@ static void drbd_disconnect(struct drbd_conf *mdev)
 		drbd_request_state(mdev, NS(conn, C_STANDALONE));
 	}
 
+	/* serialize with bitmap writeout triggered by the state change,
+	 * if any. */
+	wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));
+
 	/* tcp_close and release of sendpage pages can be deferred.  I don't
 	 * want to use SO_LINGER, because apparently it can be deferred for
 	 * more than 20 seconds (longest time I checked).