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Commit 9d1764b9 authored by Xie Yongji's avatar Xie Yongji Committed by Greg Kroah-Hartman
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nbd: Fix hung on disconnect request if socket is closed before 



[ Upstream commit 491bf8f236fdeec698fa6744993f1ecf3fafd1a5 ]

When userspace closes the socket before sending a disconnect
request, the following I/O requests will be blocked in
wait_for_reconnect() until dead timeout. This will cause the
following disconnect request also hung on blk_mq_quiesce_queue().
That means we have no way to disconnect a nbd device if there
are some I/O requests waiting for reconnecting until dead timeout.
It's not expected. So let's wake up the thread waiting for
reconnecting directly when a disconnect request is sent.

Reported-by: default avatarXu Jianhai <zero.xu@bytedance.com>
Signed-off-by: default avatarXie Yongji <xieyongji@bytedance.com>
Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/20220322080639.142-1-xieyongji@bytedance.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent abe7554d

drivers/block/nbd.c

+9 −4
Original line number Diff line number Diff line
@@ -865,11 +865,15 @@ static int wait_for_reconnect(struct nbd_device *nbd) 
	struct nbd_config *config = nbd->config;

	if (!config->dead_conn_timeout)

		return 0;

	if (test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags))

		return 0;

	return wait_event_timeout(config->conn_wait,



	if (!wait_event_timeout(config->conn_wait,

				test_bit(NBD_RT_DISCONNECTED,

					 &config->runtime_flags) ||

				atomic_read(&config->live_connections) > 0,

				  config->dead_conn_timeout) > 0;

				config->dead_conn_timeout))

		return 0;



	return !test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags);

}



static int nbd_handle_cmd(struct nbd_cmd *cmd, int index)
@@ -2014,6 +2018,7 @@ static void nbd_disconnect_and_put(struct nbd_device *nbd) 
	mutex_lock(&nbd->config_lock);

	nbd_disconnect(nbd);

	sock_shutdown(nbd);

	wake_up(&nbd->config->conn_wait);

	/*

	 * Make sure recv thread has finished, so it does not drop the last

	 * config ref and try to destroy the workqueue from inside the work