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Commit d7d94d48 authored by Josef Bacik's avatar Josef Bacik Committed by Jens Axboe
Browse files

nbd: don't requeue the same request twice. 



We can race with the snd timeout and the per-request timeout and end up
requeuing the same request twice.  We can't use the send_complete
completion to tell if everything is ok because we hold the tx_lock
during send, so the timeout stuff will block waiting to mark the socket
dead, and we could be marked complete and still requeue.  Instead add a
flag to the socket so we know whether we've been requeued yet.

Signed-off-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 70dbcc22

drivers/block/nbd.c

+18 −3
Original line number Diff line number Diff line
@@ -112,12 +112,15 @@ struct nbd_device { 
	struct task_struct *task_setup;

};



#define NBD_CMD_REQUEUED	1



struct nbd_cmd {

	struct nbd_device *nbd;

	int index;

	int cookie;

	struct completion send_complete;

	blk_status_t status;

	unsigned long flags;

};



#if IS_ENABLED(CONFIG_DEBUG_FS)
@@ -146,6 +149,14 @@ static inline struct device *nbd_to_dev(struct nbd_device *nbd) 
	return disk_to_dev(nbd->disk);

}



static void nbd_requeue_cmd(struct nbd_cmd *cmd)

{

	struct request *req = blk_mq_rq_from_pdu(cmd);



	if (!test_and_set_bit(NBD_CMD_REQUEUED, &cmd->flags))

		blk_mq_requeue_request(req, true);

}



static const char *nbdcmd_to_ascii(int cmd)

{

	switch (cmd) {
@@ -343,7 +354,7 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req, 
					nbd_mark_nsock_dead(nbd, nsock, 1);

				mutex_unlock(&nsock->tx_lock);

			}

			blk_mq_requeue_request(req, true);

			nbd_requeue_cmd(cmd);

			nbd_config_put(nbd);

			return BLK_EH_DONE;

		}
@@ -500,6 +511,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) 
				nsock->pending = req;

				nsock->sent = sent;

			}

			set_bit(NBD_CMD_REQUEUED, &cmd->flags);

			return BLK_STS_RESOURCE;

		}

		dev_err_ratelimited(disk_to_dev(nbd->disk),
@@ -541,6 +553,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) 
					 */

					nsock->pending = req;

					nsock->sent = sent;

					set_bit(NBD_CMD_REQUEUED, &cmd->flags);

					return BLK_STS_RESOURCE;

				}

				dev_err(disk_to_dev(nbd->disk),
@@ -805,7 +818,7 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index) 
	 */

	blk_mq_start_request(req);

	if (unlikely(nsock->pending && nsock->pending != req)) {

		blk_mq_requeue_request(req, true);

		nbd_requeue_cmd(cmd);

		ret = 0;

		goto out;

	}
@@ -818,7 +831,7 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index) 
		dev_err_ratelimited(disk_to_dev(nbd->disk),

				    "Request send failed, requeueing\n");

		nbd_mark_nsock_dead(nbd, nsock, 1);

		blk_mq_requeue_request(req, true);

		nbd_requeue_cmd(cmd);

		ret = 0;

	}

out:
@@ -843,6 +856,7 @@ static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx, 
	 * done sending everything over the wire.

	 */

	init_completion(&cmd->send_complete);

	clear_bit(NBD_CMD_REQUEUED, &cmd->flags);



	/* We can be called directly from the user space process, which means we

	 * could possibly have signals pending so our sendmsg will fail.  In
@@ -1460,6 +1474,7 @@ static int nbd_init_request(struct blk_mq_tag_set *set, struct request *rq, 
{

	struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq);

	cmd->nbd = set->driver_data;

	cmd->flags = 0;

	return 0;

}