From: Sagi Grimberg <sagi@grimberg.me>
To: James Smart <james.smart@broadcom.com>,
Chao Leng <lengchao@huawei.com>,
linux-nvme@lists.infradead.org
Cc: kbusch@kernel.org, axboe@fb.com, hch@lst.de
Subject: Re: [PATCH] nvme-rdma: fix deadlock when delete ctrl due to reconnect fail
Date: Tue, 28 Jul 2020 09:27:26 -0700 [thread overview]
Message-ID: <f10304ea-3955-8692-9324-62901e729115@grimberg.me> (raw)
In-Reply-To: <1288e338-9e92-eeeb-6f7b-86590c6e1a4c@broadcom.com>
>>> The io will do not fail. If work with native multipath or dm-multipath,
>>> nvme_rdma_queue_rq will return io error, and then multipath will
>>> fail over to other path and retry io, this is we expected. If work
>>> without multipath, nvme_rdma_queue_rq will return BLK_STS_RESOURCE,
>>> and then the upper layer will requeue and retry. Surely there is a
>>> weakness:the io will retry repeated every BLK_MQ_RESOURCE_DELAY(3ms)
>>> while reconnecting. Because controller reset may need long time,
>>> and nvme over roce is mainly used with multipath software, so when
>>> controller reset we expect fail over to other path and retry io,, just
>>> like error recovery. If work without multipath, we tolerate repeated
>>> I/O retries during error recovery or controller reset.
>>
>> I/O should not fail during reset, mpath or not, period.
>
> except when marked as an internal io (one used for reconnect, or maybe
> an ioctl) or marked for mpath.
I meant normal fs I/O, from the user perspective.
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prev parent reply other threads:[~2020-07-28 16:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-27 8:09 [PATCH] nvme-rdma: fix deadlock when delete ctrl due to reconnect fail Chao Leng
2020-07-27 18:44 ` Sagi Grimberg
2020-07-27 23:31 ` Sagi Grimberg
2020-07-28 3:06 ` Chao Leng
2020-07-28 3:32 ` Sagi Grimberg
[not found] ` <1288e338-9e92-eeeb-6f7b-86590c6e1a4c@broadcom.com>
2020-07-28 16:27 ` Sagi Grimberg [this message]
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