nvme/tcp: fix bug on double requeue when send fails

When nvme_tcp_io_work() fails to send to socket due to
connection close/reset, error_recovery work is triggered
from nvme_tcp_state_change() socket callback.
This cancels all the active requests in the tagset,
which requeues them.

The failed request, however, was ended and thus requeued
individually as well unless send returned -EPIPE.
Another return code to be treated the same way is -ECONNRESET.

Double requeue caused BUG_ON(blk_queued_rq(rq))
in blk_mq_requeue_request() from either the individual requeue
of the failed request or the bulk requeue from
blk_mq_tagset_busy_iter(, nvme_cancel_request, );
Signed-off-by: Anton Eidelman <anton@lightbitslabs.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/host/tcp.c

@@ -1054,7 +1054,12 @@ static void nvme_tcp_io_work(struct work_struct *w)
 		} else if (unlikely(result < 0)) {
 			dev_err(queue->ctrl->ctrl.device,
 				"failed to send request %d\n", result);
-			if (result != -EPIPE)
+
+			/*
+			 * Fail the request unless peer closed the connection,
+			 * in which case error recovery flow will complete all.
+			 */
+			if ((result != -EPIPE) && (result != -ECONNRESET))
 				nvme_tcp_fail_request(queue->request);
 			nvme_tcp_done_send_req(queue);
 			return;