Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Subject: Re: [PROBLEM] nbd requests become stuck when devices watched by
 inotify emit udev uevent changes
To:     Josef Bacik <josef@toxicpanda.com>,
        Matthew Ruffell <matthew.ruffell@canonical.com>
CC:     Jens Axboe <axboe@kernel.dk>,
        linux-block <linux-block@vger.kernel.org>,
        nbd <nbd@other.debian.org>,
        Linux Kernel <linux-kernel@vger.kernel.org>
References: <20220422054224.19527-1-matthew.ruffell@canonical.com>
 <CAEzrpqe=LD3DQcEeLXmmFuq7cX_dAQ6DOCuJYWBoZWKKTmoTzA@mail.gmail.com>
 <CAKAwkKt3yMOOW3NXcE91WkGr+8xj050CYP2pLoQVHt_2wXq=-w@mail.gmail.com>
 <CAKAwkKvfFn18RjupuqGpx4QeAiMYKSq7QUTd3wEL=pkZ+BENpQ@mail.gmail.com>
 <Yn5Zf6lONff1AoOA@localhost.localdomain>
From:   "yukuai (C)" <yukuai3@huawei.com>
Message-ID: <6efae367-12fa-1a58-7438-1b39dc0d6ef8@huawei.com>
Date:   Sat, 14 May 2022 11:39:25 +0800
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101
 Thunderbird/60.8.0
MIME-Version: 1.0
In-Reply-To: <Yn5Zf6lONff1AoOA@localhost.localdomain>
Content-Type: text/plain; charset="gbk"; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk

?? 2022/05/13 21:13, Josef Bacik д??:
> On Fri, May 13, 2022 at 02:56:18PM +1200, Matthew Ruffell wrote:
>> Hi Josef,
>>
>> Just a friendly ping, I am more than happy to test a patch, if you send it
>> inline in the email, since the pastebin you used expired after 1 day, and I
>> couldn't access it.
>>
>> I came across and tested Yu Kuai's patches [1][2] which are for the same issue,
>> and they indeed fix the hang. Thank you Yu.
>>
>> [1] nbd: don't clear 'NBD_CMD_INFLIGHT' flag if request is not completed
>> https://lists.debian.org/nbd/2022/04/msg00212.html
>>
>> [2] nbd: fix io hung while disconnecting device
>> https://lists.debian.org/nbd/2022/04/msg00207.html
>>
>> I am also happy to test any patches to fix the I/O errors.
>>
> 
> Sorry, you caught me on vacation before and I forgot to reply.  Here's part one
> of the patch I wanted you to try which fixes the io hung part.  Thanks,
> 
> Josef
> 
>   
>>From 0a6123520380cb84de8ccefcccc5f112bce5efb6 Mon Sep 17 00:00:00 2001
> Message-Id: <0a6123520380cb84de8ccefcccc5f112bce5efb6.1652447517.git.josef@toxicpanda.com>
> From: Josef Bacik <josef@toxicpanda.com>
> Date: Sat, 23 Apr 2022 23:51:23 -0400
> Subject: [PATCH] timeout thing
> 
> ---
>   drivers/block/nbd.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> index 526389351784..ab365c0e9c04 100644
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -1314,7 +1314,10 @@ static void nbd_config_put(struct nbd_device *nbd)
>   		kfree(nbd->config);
>   		nbd->config = NULL;
>   
> -		nbd->tag_set.timeout = 0;
> +		/* Reset our timeout to something sane. */
> +		nbd->tag_set.timeout = 30 * HZ;
> +		blk_queue_rq_timeout(nbd->disk->queue, 30 * HZ);
> +
>   		nbd->disk->queue->limits.discard_granularity = 0;
>   		nbd->disk->queue->limits.discard_alignment = 0;
>   		blk_queue_max_discard_sectors(nbd->disk->queue, 0);
> 
Hi, Josef

This seems to try to fix the same problem that I described here:

nbd: fix io hung while disconnecting device
https://lists.debian.org/nbd/2022/04/msg00207.html

There are still some io that are stuck, which means the devcie is
probably still opened. Thus nbd_config_put() can't reach here.
I'm afraid this patch can't fix the io hung.

Matthew, can you try a test with this patch together with my patch below
to comfirm my thought?

nbd: don't clear 'NBD_CMD_INFLIGHT' flag if request is not completed
https://lists.debian.org/nbd/2022/04/msg00212.html.

Thanks,
Kuai