[PATCH V2 0/2] nvme: Support for fused NVME_IOCTL_SUBMIT_IO

[Chaitanya Kulkarni]

On 1/26/21 10:17 AM, Clay Mayers wrote:
>> From: Chaitanya Kulkarni <Chaitanya.Kulkarni at wdc.com>
>> Sent: Monday, January 25, 2021 5:43 PM
>> To: Clay Mayers <Clay.Mayers at kioxia.com>; linux-nvme at lists.infradead.org
>> Cc: Keith Busch <kbusch at kernel.org>; Jens Axboe <axboe at fb.com>;
>> Christoph Hellwig <hch at lst.de>; Sagi Grimberg <sagi at grimberg.me>
>> Subject: Re: [PATCH V2 0/2] nvme: Support for fused
>> NVME_IOCTL_SUBMIT_IO
>>
>> On 1/25/21 12:03, clay.mayers at kioxia.com wrote:
>>> Local pci device fused support is also necessary for NVMeOF targets to
>>> support fused operation.
>> Please explain the use case and the application of the NVMeOF fuse
>> command feature.
> NVMeOF devices are used to create disaggregated storage systems
> where compute and storage are connected over a fabric.  Fused
> compare/write can be used to arbitrate shared access to NVMeOF devices
> w/o a central authority.
>
> A specific example of how fused compare/write is used is the clustered
> file system VMFS.  It uses the SCSI version of compare/write to manage
> meta data on shared SAN systems.  File system meta data is updated
> using locks stored on the storage media.  Those locks are grabbed using
> fused compare/write operations as an atomic test & set.  VMFS originally
> used device reserve, which is a courser gained locking mechanism but it
> doesn't scale as well as an atomic test & set.
If I understand correctly VMFS is out of tree filesystem is it ?
Can you please explain the setup in detail ? what kind of interface
file-system is using to issue the command ?


Based on your description it looks like target is connected to the
vmware based system and host is vmware based host and not the linux
host which is present in this series.
Also what are other applications or is this the only one application?
>