Commit 5bded4ef authored Apr 16, 2015 by Lars Ellenberg Committed by Jens Axboe Nov 25, 2015

drbd: don't block forever in disconnect during resync if fencing=r-a-stonith



Disconnect should wait for pending bitmap IO.
But if that bitmap IO is not happening, because it is waiting for
pending application IO, and there is no progress, because the fencing
policy suspended application IO because of the disconnect,
then we deadlock.

The bitmap writeout in this case does not care for concurrent
application IO, so there is no point waiting for it.

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

parent bb649b34

drivers/block/drbd/drbd_main.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -3563,7 +3563,9 @@ void drbd_queue_bitmap_io(struct drbd_device *device,

		spin_lock_irq(&device->resource->req_lock);
		set_bit(BITMAP_IO, &device->flags);
		if (atomic_read(&device->ap_bio_cnt) == 0) {
		/* don't wait for pending application IO if the caller indicates that
		* application IO does not conflict anyways. */
		if (flags == BM_LOCKED_CHANGE_ALLOWED \|\| atomic_read(&device->ap_bio_cnt) == 0) {
		if (!test_and_set_bit(BITMAP_IO_QUEUED, &device->flags))
		drbd_queue_work(&first_peer_device(device)->connection->sender_work,
		&device->bm_io_work.w);