[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <52498F68.8050200@redhat.com>
Date: Mon, 30 Sep 2013 09:49:12 -0500
From: Ric Wheeler <rwheeler@...hat.com>
To: Miklos Szeredi <miklos@...redi.hu>
CC: "J. Bruce Fields" <bfields@...ldses.org>,
"Myklebust, Trond" <Trond.Myklebust@...app.com>,
Zach Brown <zab@...hat.com>,
Anna Schumaker <schumaker.anna@...il.com>,
Kernel Mailing List <linux-kernel@...r.kernel.org>,
Linux-Fsdevel <linux-fsdevel@...r.kernel.org>,
"linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
"Schumaker, Bryan" <Bryan.Schumaker@...app.com>,
"Martin K. Petersen" <mkp@....net>, Jens Axboe <axboe@...nel.dk>,
Mark Fasheh <mfasheh@...e.com>,
Joel Becker <jlbec@...lplan.org>,
Eric Wong <normalperson@...t.net>
Subject: Re: [RFC] extending splice for copy offloading
On 09/30/2013 10:46 AM, Miklos Szeredi wrote:
> On Mon, Sep 30, 2013 at 4:41 PM, Ric Wheeler <rwheeler@...hat.com> wrote:
>> The way the array based offload (and some software side reflink works) is
>> not a byte by byte copy. We cannot assume that a valid count can be returned
>> or that such a count would be an indication of a sequential segment of good
>> data. The whole thing would normally have to be reissued.
>>
>> To make that a true assumption, you would have to mandate that in each of
>> the specifications (and sw targets)...
> You're missing my point.
>
> - user issues SIZE_MAX splice request
> - fs issues *64M* (or whatever) request to offload
> - when that completes *fully* then we return 64M to userspace
> - if it completes partially, then we return an error to userspace
>
> Again, wouldn't that work?
>
> Thanks,
> Miklos
Yes, if you send a copy offload command and it works, you can assume that it
worked fully. It would be pretty interesting if that were not true :)
If it fails, we cannot assume anything about partial completion.
Ric
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists