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Mon, 13 Jan 2025 07:50:46 +0000 Message-ID: <0e6dbc36-ce6f-46ba-9f35-c76562cbf42d@suse.de> Date: Mon, 13 Jan 2025 08:50:46 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] nvme: Remove namespace when nvme_identify_ns_descs() failed To: Sagi Grimberg , Hannes Reinecke , Christoph Hellwig Cc: Keith Busch , linux-nvme@lists.infradead.org References: <20241129140608.115282-1-hare@kernel.org> <9cdb72d6-291f-46a1-8c80-45ceb75e2b8b@grimberg.me> <77130bd8-5bc9-41f3-b4fc-ab41835850f7@grimberg.me> Content-Language: en-US From: Hannes Reinecke In-Reply-To: <77130bd8-5bc9-41f3-b4fc-ab41835850f7@grimberg.me> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_FIVE(0.00)[5]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:mid,suse.de:email] X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250112_235048_410934_89F07AAB X-CRM114-Status: GOOD ( 16.12 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 1/11/25 00:16, Sagi Grimberg wrote: > > > > On 08/01/2025 17:45, Hannes Reinecke wrote: >> On 1/8/25 11:49, Sagi Grimberg wrote: >>> >>> >>> >>> On 07/01/2025 10:11, Hannes Reinecke wrote: >>>> On 12/25/24 10:58, Sagi Grimberg wrote: >>>>> >>>>> >>>>> >>>>> On 29/11/2024 16:06, Hannes Reinecke wrote: >>>>>> When a namespace gets unmapped on the target during scanning >>>>>> nvme_identify_ns_descs() returns with a non-retryable error. >>>>>> With the currrent code we will ignore that error on the grounds >>>>>> that we failed to get information, and hence cannot make any >>>>>> decisions whether to keep or remove that namespace. >>>>>> But a non-retryable error implies that the namespace is _not_ >>>>>> present as we cannot retry that command and will never get >>>>>> information about that namespace. >>>>>> And we need to remove the namespace during scanning, as otherwise >>>>>> the AEN informing us about a namespace change will find the NSID >>>>>> present, but nvme_validate_ns() will fail, and the namespace >>>>>> will never be updated with the correct information. >>>>> >>>>> Isn't that a bit harsh? >>>>> I would expect to see a specific status line NVME_SC_INVALID_NS or >>>>> equivalent for a full removal of the namespace? >>>> >>>> Does it matter? If we get a DNR status back from >>>> nvme_identify_ns_descs() we _cannot_ resend that command. >>>> Meaning we cannot get the namespace descriptors. As we >>>> rely on these descriptors to properly map the namespace >>>> we cannot correctly work with it, and we're better off >>>> to pretend the namespace is gone and wait for an AEN >>>> indicating that the namespace (or controller) state has changed. >>> >>> I think it does matter. I don't think we should be removing the NS >>> without >>> the controller telling us that it is actually removed. >> >> But what would be the recovery action here? >> If the 'identify ns descs' command cannot be retried, how are >> we going to map the namespace to an ns_head? > > Let's take a step back here. Can you describe the scenario you hit? what > was the error > status that you observed? See my reply to Nilay. Target unmaps the namespace, and we get an AEN for 'namespace changed'. We start a scan, but by the time we retrieve the list of namespaces the NSID has been reassigned to another namespace with a different UUID. Then our stale namespace will be removed in nvme_validate_ns() and not rescanned. Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich