[SPDK] Re: NVMf namespace masking 2nd

Hi Jonas,

This is looking in pretty good shape.  I added some comments in the Gerrit review.

Thanks,

Jim


On 10/5/21, 12:34 AM, "Jonas Pfefferle" <pepperjo(a)japf.ch> wrote:

    Hi all,

    I updated the NVMf namespace masking PR:
    https://review.spdk.io/gerrit/c/spdk/spdk/+/7821

    Changes to RFC:
    - Address concerns of overhead of checking on IO path.
       If a namepsace is active is only checked where needed and
       validity checks for NSID is only done once.
    - Allow to hot and cold attach/detach
    - It is no longer possible to call the new RPCs without
       hostNQN. The auto attach bevahior cannot be changed
       after add_ns. We might add an additional RPC for this
       later.
    - identify ns now correctly response with zeros for
       inactive namespace
    - Address concurrency concerns: attaching/detaching
       now pauses the subsystem for changes
    - ns change log is updated on attach/detach
    - tests

    I would be happy to get some feeedback.

    Thanks,
    Jonas

      On Sat, 08 May 2021 15:37:09 +0200
      "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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