Messages in this thread | | | Date | Mon, 14 Mar 2022 08:08:08 +0100 | From | "" <> | Subject | Re: [PATCH] driver/nvme/host: Support duplicated nsid for the private |
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On Mon, Mar 14, 2022 at 04:05:05PM +0900, Sungup Moon wrote: > When the multi-controller, managed by a special admin command, has private > namespace with same nsid, current linux driver raise "Duplicate unshared > namespace" error. But, NVMe Specification defines the NSID usage like this: > > If Namespace Management, ANA Reporting, or NVM Sets are supported, the > NSIDs shall be unique within the NVM subsystem. If the Namespace > Management, ANA Reporting, and NVM Sets are not supported, then NSIDs: > a) for shared namespace shall be unique; and > b) for private namespace are not required to be unique. > (reference: 6.1.6 NSID and Namespace Usage; NVM Express 1.4c spec) > > So, if a multi-controller, which is not managed by Namespace Management > function, creates some private namespaces without ANA and NVM Sets, the > duplicated NSID should be allowed because that is not a NVMe specification > violation. > > But, current nvme driver checks only namespace is shared or not, so I > propose following patch: > 1. nvme_ctrl has unique_nsid field to identify that controller should > assign unique nsid. > 2. nvme_init_ns_head function creates new nvme_ns_head instance not only > head is null but controller's unique_nsid is false (no flagged > attribute) and namespace is not shared. > 3. for creating bdev device file, nvme_mpath_set_disk_name will return > false when unique_nsid is false and namespace is not shared. > 4. also, nvme_mpath_alloc_disk alto return 0 with same manner.
From a very quick glance this looks good. But please make sure you don't spill over 80 charactes per line. Also I think instead of adding the unique_nsid field a little helper that checks the relevant flags might be a lіttle nicer. It is not checked in a fast path anywere and the checks are pretty trivial.
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