From: Xie Yongji xieyongji@bytedance.com
[ 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: Xu Jianhai zero.xu@bytedance.com Signed-off-by: Xie Yongji xieyongji@bytedance.com Reviewed-by: Josef Bacik josef@toxicpanda.com Link: https://lore.kernel.org/r/20220322080639.142-1-xieyongji@bytedance.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/block/nbd.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 59c452fff835..ecde800ba210 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -880,11 +880,15 @@ 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)) + + 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)) return 0; - return wait_event_timeout(config->conn_wait, - atomic_read(&config->live_connections) > 0, - config->dead_conn_timeout) > 0; + + return !test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags); }
static int nbd_handle_cmd(struct nbd_cmd *cmd, int index) @@ -2029,6 +2033,7 @@ 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