Re: [RFC PATCH DONOTMERGE v2 0/6] userspace PI passthrough via AIO/DIO

[Zach Brown <zab@redhat.com>]

On Mon, Mar 24, 2014 at 09:22:31AM -0700, Darrick J. Wong wrote:
> This RFC provides a rough implementation of a mechanism to allow
> userspace to attach protection information (e.g. T10 DIF) data to a
> disk write and to receive the information alongside a disk read.

I have some comments for you! :)  Mostly about the interface up in aio.
I don't have all that much to say about the bio/pi bits.

> Patch #2 implements a generic IO extension interface so that we can
> receive a struct io_extension from userspace containing the structure
> size, a flag telling us which extensions we'd like to use (ie_has),
> and (eventually) extension data.  There's a small framework for
> mapping ie_has bits to actual extensions.

I still really don't think that we should be thinking of these as
generic extensions.  We're talking about arguments to syscalls.  's a
small number of them with strong semantics because they're a part of the
syscall ABI.  I don't think we should implement them by iterating over
per-field ops structs.

Anyway, more in reply to the patches.

- z

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