[SPDK] Re: RFC: NVMf namespace masking

Thanks Jonas!

For those that are interested in this topic, please head over to Jonas' RFC patch on Gerrit (https://review.spdk.io/gerrit/c/spdk/spdk/+/7821).  There is already quite a bit of good discussion happening there.

-Jim


On 5/8/21, 6:38 AM, "Jonas Pfefferle" <pepperjo(a)japf.ch> wrote:

    Hi all,

    I would be happy to get some feedback on my NVMf target namespace masking 
    implementation using attach/detach:
    https://review.spdk.io/gerrit/c/spdk/spdk/+/7821

    The patch introduces namespace masking for NVMe-over-fabrics
    targets by allowing to (dynamically) attach and detach
    controllers to/from namespaces, cf. NVMe spec 1.4 - section 6.1.4.
    Since SPDK only supports the dynamic controller model a new
    controller is allocated on every fabric connect command.
    This allows to attach/detach controllers of a specific
    host NQN to/from a namespace. A host can only perform
    operations to an active namespace. Inactive namespaces can
    be listed (not supported by SPDK) but no additional
    information can be retrieved:
    "Unless otherwise noted, specifying an inactive NSID in a
    command that uses the Namespace Identifier (NSID) field shall
    cause the controller to abort the command with status
    Invalid Field in Command" - NVMe spec 1.4 - section 6.1.5
    Note that this patch does not implement the NVMe namespace
    attachment command but allows to attach/detach via RPCs only.
    To preserve current behavior all controllers are auto attached.
    To not not auto attach controllers the nvmf_subsystem_add_ns
    shall be called with "--no-auto-attach". We introduce two new
    RPC calls:
    - nvmf_ns_attach_ctrlr <subsysNQN> <NSID> [--host <hostNQN>]
    - nvmf_ns_detach_ctrlr <subsysNQN> <NSID> [--host <hostNQN>]
    If no host NQN is specified all controllers
    (new and currently connected) will attach/detach to/from the
    namespace specified.
    The list in spdk_nvmf_ns is used to keep track of hostNQNs
    which controllers should be attached on connect.
    The active_ns array in spdk_nvmf_ctrlr is used for fast lookup
    to check whether a NSID is active/inactive on command execution.

    Thanks,
    Jonas
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