[PATCH v4] nvme: add vectored-io support for user-passthru

[Christoph Hellwig]

On Mon, Feb 28, 2022 at 06:11:39PM +0530, Kanchan Joshi wrote:
> On Mon, Feb 28, 2022 at 5:18 PM Christoph Hellwig <hch at lst.de> wrote:
> >
> > Btw, I noticed this is not wired up for the /dev/ngX character device.
> > Can you send a follow on patch for that?
> 
> Err, do you see that it is not working? I actually tested it over both
> block and char.
> My test utility did write-vectored to /dev/nvme0n1 followed by
> read-vectored from /dev/ng0n1, and did data-comparison. It passed.
> 
> Code wise, the handler for NVME_IOCTL_IO64_CMD_VEC is added insided
> nvme_ns_ioctl().
> - for non-multipath char node:
> nvme_ns_chr_ioctl -> __nvme_ioctl -> nvme_ns_ioctl
> - for multipath char node:
>  nvme_ns_head_chr_ioctl -> nvme_ns_ioctl
> 
> Please let me know how I can produce the failure that you see.

You're right.  We do support it for /dev/ngX, just not the /dev/nvmeX
character devices, which is a good thing.