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From:   pkalever@redhat.com
To:     linux-kernel@vger.kernel.org
Cc:     linux-block@vger.kernel.org, nbd@other.debian.org,
        josef@toxicpanda.com, axboe@kernel.dk, idryomov@redhat.com,
        xiubli@redhat.com,
        Prasanna Kumar Kalever <prasanna.kalever@redhat.com>
Subject: [PATCH v1 2/2] nbd: reset the queue/io_timeout to default on disconnect
Date:   Fri,  6 Aug 2021 19:59:14 +0530
Message-Id: <20210806142914.70556-3-pkalever@redhat.com>
In-Reply-To: <20210806142914.70556-1-pkalever@redhat.com>
References: <20210806142914.70556-1-pkalever@redhat.com>
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From: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>

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@redhat.com>
---
 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