nbd: restore default timeout when setting it to zero

If we configured io timeout of nbd0 to 100s. Later after we
finished using it, we configured nbd0 again and set the io
timeout to 0. We expect it would timeout after 30 seconds
and keep retry. But in fact we could not change the timeout
when we set it to 0. the timeout is still the original 100s.

So change the timeout to default 30s when we set it to zero.
It also behaves same as commit 2da22da57348 ("nbd: fix zero
cmd timeout handling v2").

It becomes more important if we were reconfigure a nbd device
and the io timeout it set to zero. Because it could take 30s
to detect the new socket and thus io could be completed more
quickly compared to 100s.

Signed-off-by: Hou Pu <houpu@bytedance.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 3ff4054d6834d25f2b8afae4e99d5e2db2994f4e..edf8b632e3d27b4b907a52dd55e41e3a6b8a03ef 100644 (file)
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1363,6 +1363,8 @@ static void nbd_set_cmd_timeout(struct nbd_device *nbd, u64 timeout)
        nbd->tag_set.timeout = timeout * HZ;
        if (timeout)
                blk_queue_rq_timeout(nbd->disk->queue, timeout * HZ);
+       else
+               blk_queue_rq_timeout(nbd->disk->queue, 30 * HZ);
 }
 
 /* Must be called with config_lock held */