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From: Yao Liu <yotta.liu@ucloud.cn>
To: Josef Bacik <josef@toxicpanda.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>
Subject: Re: Re: [PATCH 1/3] nbd: fix connection timed out error after reconnecting to server
Date: Tue, 28 May 2019 02:07:43 +0800	[thread overview]
Message-ID: <20190527180743.GA20702@192-168-150-246.7~> (raw)
In-Reply-To: <20190524130740.zfypc2j3q5e3gryr@MacBook-Pro-91.local.dhcp.thefacebook.com>

On Fri, May 24, 2019 at 09:07:42AM -0400, Josef Bacik wrote:
> On Fri, May 24, 2019 at 05:43:54PM +0800, Yao Liu wrote:
> > Some I/O requests that have been sent succussfully but have not yet been
> > replied won't be resubmitted after reconnecting because of server restart,
> > so we add a list to track them.
> > 
> > Signed-off-by: Yao Liu <yotta.liu@ucloud.cn>
> 
> Nack, this is what the timeout stuff is supposed to handle.  The commands will
> timeout and we'll resubmit them if we have alive sockets.  Thanks,
> 
> Josef
> 

On the one hand, if num_connections == 1 and the only sock has dead,
then we do nbd_genl_reconfigure to reconnect within dead_conn_timeout,
nbd_xmit_timeout will not resubmit commands that have been sent
succussfully but have not yet been replied. The log is as follows:
 
[270551.108746] block nbd0: Receive control failed (result -104)
[270551.108747] block nbd0: Send control failed (result -32)
[270551.108750] block nbd0: Request send failed, requeueing
[270551.116207] block nbd0: Attempted send on invalid socket
[270556.119584] block nbd0: reconnected socket
[270581.161751] block nbd0: Connection timed out
[270581.165038] block nbd0: shutting down sockets
[270581.165041] print_req_error: I/O error, dev nbd0, sector 5123224 flags 8801
[270581.165149] print_req_error: I/O error, dev nbd0, sector 5123232 flags 8801
[270581.165580] block nbd0: Connection timed out
[270581.165587] print_req_error: I/O error, dev nbd0, sector 844680 flags 8801
[270581.166184] print_req_error: I/O error, dev nbd0, sector 5123240 flags 8801
[270581.166554] block nbd0: Connection timed out
[270581.166576] print_req_error: I/O error, dev nbd0, sector 844688 flags 8801
[270581.167124] print_req_error: I/O error, dev nbd0, sector 5123248 flags 8801
[270581.167590] block nbd0: Connection timed out
[270581.167597] print_req_error: I/O error, dev nbd0, sector 844696 flags 8801
[270581.168021] print_req_error: I/O error, dev nbd0, sector 5123256 flags 8801
[270581.168487] block nbd0: Connection timed out
[270581.168493] print_req_error: I/O error, dev nbd0, sector 844704 flags 8801
[270581.170183] print_req_error: I/O error, dev nbd0, sector 5123264 flags 8801
[270581.170540] block nbd0: Connection timed out
[270581.173333] block nbd0: Connection timed out
[270581.173728] block nbd0: Connection timed out
[270581.174135] block nbd0: Connection timed out
 
On the other hand, if we wait nbd_xmit_timeout to handle resubmission,
the I/O requests will have a big delay. For example, if timeout time is 30s,
and from sock dead to nbd_genl_reconfigure returned OK we only spend
2s, the I/O requests will still be handled by nbd_xmit_timeout after 30s.

  reply	other threads:[~2019-05-28  8:34 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-24  9:43 Yao Liu
2019-05-24  9:43 ` [PATCH 2/3] nbd: notify userland even if nbd has already disconnected Yao Liu
2019-05-24 13:08   ` Josef Bacik
2019-05-27 18:23     ` Yao Liu
2019-05-28 16:36       ` Mike Christie
2019-05-28 20:05         ` Yao Liu
2019-05-28 16:54       ` Josef Bacik
2019-05-24  9:43 ` [PATCH 3/3] nbd: mark sock as dead even if it's the last one Yao Liu
2019-05-24 13:17   ` Josef Bacik
2019-05-27 18:29     ` Yao Liu
2019-05-24 13:07 ` [PATCH 1/3] nbd: fix connection timed out error after reconnecting to server Josef Bacik
2019-05-27 18:07   ` Yao Liu [this message]
2019-05-28 16:57     ` Josef Bacik
2019-05-28 19:04       ` Yao Liu
2019-05-29 13:49         ` Josef Bacik

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