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From:   Trond Myklebust <trondmy@hammerspace.com>
To:     David Howells <dhowells@redhat.com>
CC:     Matthew Wilcox <willy@infradead.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
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        Jens Axboe <axboe@kernel.dk>,
        Jeffrey Layton <jlayton@kernel.org>,
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Subject: Re: [RFC PATCH] iov_iter: Add an iterator-of-iterators
Thread-Topic: [RFC PATCH] iov_iter: Add an iterator-of-iterators
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Date:   Wed, 22 Mar 2023 18:47:09 +0000
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> On Mar 22, 2023, at 14:15, David Howells <dhowells@redhat.com> wrote:
>=20
> Trond Myklebust <trondmy@hammerspace.com> wrote:
>=20
>> Add an enum iter_type for ITER_ITER ? :-)
>=20
> Well, you asked for it...  It's actually fairly straightforward once
> ITER_PIPE is removed.
>=20
> ---
> iov_iter: Add an iterator-of-iterators
>=20
> Provide an I/O iterator that takes an array of iterators and iterates ove=
r
> them in turn.  Then make the sunrpc service code (and thus nfsd) use it.
>=20
> In this particular instance, the svc_tcp_sendmsg() sets up an array of
> three iterators: once for the marker+header, one for the body and one
> optional one for the tail, then sets msg_iter to be an
> iterator-of-iterators across them.

Cool! This is something that can be used on the receive side as well, so ve=
ry useful. I can imagine it might also open up a few more use cases for ITE=
R_XARRAY.

Thanks!
  Trond

_________________________________
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com