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Mon, 10 Aug 2020 13:22:15 -0400 X-MC-Unique: fhPGPgvDMNSjnkgJuz-B7g-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A601A8005B0; Mon, 10 Aug 2020 17:22:13 +0000 (UTC) Received: from localhost (unknown [10.18.25.174]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7DF366111F; Mon, 10 Aug 2020 17:22:10 +0000 (UTC) Date: Mon, 10 Aug 2020 13:22:09 -0400 From: Mike Snitzer To: Sagi Grimberg Subject: [PATCH] nvme: explicitly use normal NVMe error handling when appropriate Message-ID: <20200810172209.GA19535@redhat.com> References: <729820BC-5F38-4E22-A83A-862E57BAE201@netapp.com> <20200806184057.GA27858@redhat.com> <20200806191943.GA27868@redhat.com> <6B826235-C504-4621-B8F7-34475B200979@netapp.com> <20200807000755.GA28957@redhat.com> <510f5aff-0437-b1ce-f7ab-c812edbea880@grimberg.me> <20200807045015.GA29737@redhat.com> <20200810143620.GA19127@redhat.com> MIME-Version: 1.0 In-Reply-To: <20200810143620.GA19127@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=msnitzer@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200810_132219_402012_AD81DD39 X-CRM114-Status: GOOD ( 27.12 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Hannes Reinecke , "linux-nvme@lists.infradead.org" , Christoph Hellwig , dm-devel@redhat.com, Ewan Milne , Chao Leng , Keith Busch , "Meneghini, John" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Mon, Aug 10 2020 at 10:36am -0400, Mike Snitzer wrote: > On Fri, Aug 07 2020 at 7:35pm -0400, > Sagi Grimberg wrote: > > > > > >>Hey Mike, ... > > >I think NVMe can easily fix this by having an earlier stage of checking, > > >e.g. nvme_local_retry_req(), that shortcircuits ever getting to > > >higher-level multipathing consideration (be it native NVMe or DM > > >multipathing) for cases like NVME_SC_CMD_INTERRUPTED. > > >To be clear: the "default" case of nvme_failover_req() that returns > > >false to fallback to NVMe's "local" normal NVMe error handling -- that > > >can stay.. but a more explicit handling of cases like > > >NVME_SC_CMD_INTERRUPTED should be added to a nvme_local_retry_req() > > >check that happens before nvme_failover_req() in nvme_complete_rq(). > > > > I don't necessarily agree with having a dedicated nvme_local_retry_req(). > > a request that isn't failed over, goes to local error handling (retry or > > not). I actually think that just adding the condition to > > nvme_complete_req and having nvme_failover_req reject it would work. > > > > Keith? > > I think that is basically what I'm thinking too. From: Mike Snitzer Subject: nvme: explicitly use normal NVMe error handling when appropriate Commit 764e9332098c0 ("nvme-multipath: do not reset on unknown status"), among other things, fixed NVME_SC_CMD_INTERRUPTED error handling by changing multipathing's nvme_failover_req() to short-circuit path failover and then fallback to NVMe's normal error handling (which takes care of NVME_SC_CMD_INTERRUPTED). This detour through native NVMe multipathing code is unwelcome because it prevents NVMe core from handling NVME_SC_CMD_INTERRUPTED independent of any multipathing concerns. Introduce nvme_status_needs_local_error_handling() to prioritize non-failover retry, when appropriate, in terms of normal NVMe error handling. nvme_status_needs_local_error_handling() will naturely evolve to include handling of any other errors that normal error handling must be used for. nvme_failover_req()'s ability to fallback to normal NVMe error handling has been preserved because it may be useful for future NVME_SC that nvme_status_needs_local_error_handling() hasn't yet been trained for. Signed-off-by: Mike Snitzer --- drivers/nvme/host/core.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 88cff309d8e4..be749b690af7 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -252,6 +252,16 @@ static inline bool nvme_req_needs_retry(struct request *req) return true; } +static inline bool nvme_status_needs_local_error_handling(u16 status) +{ + switch (status & 0x7ff) { + case NVME_SC_CMD_INTERRUPTED: + return true; + default: + return false; + } +} + static void nvme_retry_req(struct request *req) { struct nvme_ns *ns = req->q->queuedata; @@ -270,7 +280,8 @@ static void nvme_retry_req(struct request *req) void nvme_complete_rq(struct request *req) { - blk_status_t status = nvme_error_status(nvme_req(req)->status); + u16 nvme_status = nvme_req(req)->status; + blk_status_t status = nvme_error_status(nvme_status); trace_nvme_complete_rq(req); @@ -280,7 +291,8 @@ void nvme_complete_rq(struct request *req) nvme_req(req)->ctrl->comp_seen = true; if (unlikely(status != BLK_STS_OK && nvme_req_needs_retry(req))) { - if ((req->cmd_flags & REQ_NVME_MPATH) && nvme_failover_req(req)) + if (!nvme_status_needs_local_error_handling(nvme_status) && + (req->cmd_flags & REQ_NVME_MPATH) && nvme_failover_req(req)) return; if (!blk_queue_dying(req->q)) { -- 2.18.0 _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme