nbd: add missing config put

Fix bug added with the patch:

commit 8f3ea35929a0806ad1397db99a89ffee0140822a
Author: Josef Bacik <josef@toxicpanda.com>
Date:   Mon Jul 16 12:11:35 2018 -0400

    nbd: handle unexpected replies better

where if the timeout handler runs when the completion path is and we fail
to grab the mutex in the timeout handler we will leave a config reference
and cannot free the config later.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index c6ff8f922fd7e0b806626f1f1bf8fc02d58bcf42..ebc98cf76365bba8d851f76cfaf90ec59f0281ed 100644 (file)
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -373,8 +373,10 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
        }
        config = nbd->config;
 
-       if (!mutex_trylock(&cmd->lock))
+       if (!mutex_trylock(&cmd->lock)) {
+               nbd_config_put(nbd);
                return BLK_EH_RESET_TIMER;
+       }
 
        if (config->num_connections > 1) {
                dev_err_ratelimited(nbd_to_dev(nbd),