[PATCH v1 2/2] nbd: reset the queue/io_timeout to default on disconnect

From: pkalever
Date: Fri Aug 06 2021 - 10:30:07 EST


From: Prasanna Kumar Kalever <prasanna.kalever@xxxxxxxxxx>

Without any changes to NBD_ATTR_TIMEOUT (default is 30 secs),
$ rbd-nbd map rbd-pool/image0 --try-netlink
/dev/nbd0
$ cat /sys/block/nbd0/queue/io_timeout
30000
$ rbd-nbd unmap /dev/nbd0
$ cat /sys/block/nbd0/queue/io_timeout
30000

Now user sets NBD_ATTR_TIMEOUT to 60,
$ rbd-nbd map rbd-pool/image0 --try-netlink --io-timeout 60
/dev/nbd0
$ cat /sys/block/nbd0/queue/io_timeout
60000
$ rbd-nbd unmap /dev/nbd0
$ cat /sys/block/nbd0/queue/io_timeout
60000

Now user doesn't alter NBD_ATTR_TIMEOUT, but sysfs still shows it as 60,
$ rbd-nbd map rbd-pool/image0 --try-netlink
/dev/nbd0
$ cat /sys/block/nbd0/queue/io_timeout
60000
$ rbd-nbd unmap /dev/nbd0
$ cat /sys/block/nbd0/queue/io_timeout
60000

The problem exists with ioctl interface too.

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@xxxxxxxxxx>
---
drivers/block/nbd.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 16a1a14b1fd1..a45aabc4914b 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -158,6 +158,7 @@ static void nbd_connect_reply(struct genl_info *info, int index);
static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info);
static void nbd_dead_link_work(struct work_struct *work);
static void nbd_disconnect_and_put(struct nbd_device *nbd);
+static void nbd_set_cmd_timeout(struct nbd_device *nbd, u64 timeout);

static inline struct device *nbd_to_dev(struct nbd_device *nbd)
{
@@ -1250,7 +1251,7 @@ static void nbd_config_put(struct nbd_device *nbd)
destroy_workqueue(nbd->recv_workq);
nbd->recv_workq = NULL;

- nbd->tag_set.timeout = 0;
+ nbd_set_cmd_timeout(nbd, 0);
nbd->disk->queue->limits.discard_granularity = 0;
nbd->disk->queue->limits.discard_alignment = 0;
blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
@@ -2124,6 +2125,10 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
if (ret)
goto out;

+ /*
+ * On reconfigure, if NBD_ATTR_TIMEOUT is not provided, we will
+ * continue to use the cmd timeout provided with connect initially.
+ */
if (info->attrs[NBD_ATTR_TIMEOUT])
nbd_set_cmd_timeout(nbd,
nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]));
--
2.31.1