linux-kernel - Re: [PROBLEM] nbd requests become stuck when devices watched by inotify emit udev uevent changes

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Date:   Fri, 13 May 2022 09:13:35 -0400
From:   Josef Bacik <josef@...icpanda.com>
To:     Matthew Ruffell <matthew.ruffell@...onical.com>
Cc:     Jens Axboe <axboe@...nel.dk>,
        linux-block <linux-block@...r.kernel.org>,
        nbd <nbd@...er.debian.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>, yukuai3@...wei.com
Subject: Re: [PROBLEM] nbd requests become stuck when devices watched by
 inotify emit udev uevent changes

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@...icpanda.com>
From: Josef Bacik <josef@...icpanda.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);
-- 
2.26.3