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Date:   Fri, 23 Jun 2023 11:03:49 -0500
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Subject: Re: [PATCH net-next v4 11/15] iscsi: Use sendmsg(MSG_SPLICE_PAGES)
 rather than sendpage
To:     David Howells <dhowells@redhat.com>, netdev@vger.kernel.org
Cc:     Alexander Duyck <alexander.duyck@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
        David Ahern <dsahern@kernel.org>,
        Matthew Wilcox <willy@infradead.org>,
        Jens Axboe <axboe@kernel.dk>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Lee Duncan <lduncan@suse.com>,
        Chris Leech <cleech@redhat.com>,
        Maurizio Lombardi <mlombard@redhat.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Al Viro <viro@zeniv.linux.org.uk>, open-iscsi@googlegroups.com,
        linux-scsi@vger.kernel.org, target-devel@vger.kernel.org,
        Dimitri KRAVTCHUK <dimitri.kravtchuk@oracle.com>
References: <20230623114425.2150536-1-dhowells@redhat.com>
 <20230623114425.2150536-12-dhowells@redhat.com>
Content-Language: en-US
From:   Mike Christie <michael.christie@oracle.com>
In-Reply-To: <20230623114425.2150536-12-dhowells@redhat.com>
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On 6/23/23 6:44 AM, David Howells wrote:
> Use sendmsg() with MSG_SPLICE_PAGES rather than sendpage.  This allows
> multiple pages and multipage folios to be passed through.
> 
> TODO: iscsit_fe_sendpage_sg() should perhaps set up a bio_vec array for the
> entire set of pages it's going to transfer plus two for the header and
> trailer and page fragments to hold the header and trailer - and then call
> sendmsg once for the entire message.
> 
> Signed-off-by: David Howells <dhowells@redhat.com>
> cc: Lee Duncan <lduncan@suse.com>
> cc: Chris Leech <cleech@redhat.com>
> cc: Mike Christie <michael.christie@oracle.com>
> cc: Maurizio Lombardi <mlombard@redhat.com>
> cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
> cc: "Martin K. Petersen" <martin.petersen@oracle.com>
> cc: "David S. Miller" <davem@davemloft.net>
> cc: Eric Dumazet <edumazet@google.com>
> cc: Jakub Kicinski <kuba@kernel.org>
> cc: Paolo Abeni <pabeni@redhat.com>
> cc: Jens Axboe <axboe@kernel.dk>
> cc: Matthew Wilcox <willy@infradead.org>
> cc: Al Viro <viro@zeniv.linux.org.uk>
> cc: open-iscsi@googlegroups.com
> cc: linux-scsi@vger.kernel.org
> cc: target-devel@vger.kernel.org
> cc: netdev@vger.kernel.org
> ---
> 
> Notes:
>     ver #2)
>      - Wrap lines at 80.
> 
>  drivers/scsi/iscsi_tcp.c                 | 26 +++++++++---------------
>  drivers/scsi/iscsi_tcp.h                 |  2 --
>  drivers/target/iscsi/iscsi_target_util.c | 15 ++++++++------

When you send this again can you split it into 2 patches?

drivers/scsi/iscsi_tcp.* is one driver. It's similar to a NFS client and
it has a set of maintainers that you saw in the MAINTAINER file.

drivers/target/iscsi/iscsi_target_util.c is another driver which is similar
to a NFS server. Martin is the overall maintainer but it's a group effort
to review patches.

I've tested and reviewed the iscsi_tcp parts. You can add my:

Reviewed-by: Mike Christie <michael.christie@oracle.com>

For the iscsi_target_util.c part, I'm reviewing it now and hoping Maurizio
and/or Dimitry might review as well.

One question on the target part I had is about the TODO above. Is that
something you were going to do, or is it something you are asking the target
people to do?