[PATCH v4 04/11] block: define meta io descriptor

[Christoph Hellwig]

On Mon, Oct 21, 2024 at 10:11:35PM -0400, Martin K. Petersen wrote:
> Glad to see the seed added. In NVMe it can be a 64-bit value so we
> should bump the size of that field in the user API.
> 
> Not sure what to do about the storage tag. For Linux that would probably
> be owned by the filesystem (as opposed to the application). But I guess
> one could envision a userland application acting as a storage target and
> in that case the tag would need to be passed to the kernel.

Right now the series only supports PI on the block device.  In that
case the userspace application can clearly make use of it.  If we
want to support PI on file systems (which I'd really like to do for
XFS) both ownership models might make sense depending on the file
system, although I think just giving it to the application is going
to be the only thing we'll see for a while.  Maybe we need a way
to query if the application can use the app tag?