From: Benny Halevy <bhalevy@tonian.com>
To: Fred Isaman <faisaman4@gmail.com>,
"Myklebust, Trond" <Trond.Myklebust@netapp.com>
Cc: "Isaman, Fred" <Fred.Isaman@netapp.com>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH] pnfs: do not reset to mds if wb_offset != wb_pgbase
Date: Wed, 27 Mar 2013 14:19:01 +0200 [thread overview]
Message-ID: <5152E3B5.8080402@tonian.com> (raw)
In-Reply-To: <CADnza46Npnn=GquO8s7TPPSGZq9Cs11JJdj6t8ejDh5gYeeTYg@mail.gmail.com>
On 2013-03-19 22:28, Fred Isaman wrote:
> On Tue, Mar 19, 2013 at 3:35 PM, Benny Halevy <bhalevy@tonian.com> wrote:
>> On 2013-03-18 19:04, Fred Isaman wrote:
>>> A problem case is if the layout ends within the page request, which
>>> can happen due to the misalignment.
>>
>> First, the file layout currently supports only whole file layouts so I don't see
>> how that's a problem.
>> Regardless, I'd rather trim the layout segment to PAGE_SIZE boundaries
>> and get a new layout from the page aligned offset and on with minlength = PAGE_SIZE
>> (as we do today).
>>
>> Benny
>>
>
> Yes, but consider....
>
> let P = PAGE_SIZE
>
> assume you have a layout from 0 to 4P, and you try to do a WRITE from
> 2P to 6P. Now if the buffer is not page aligned, one of the nfs_page
> requests will contain the file's logical 4P offset at a random
> location within the nfs_page. What happens then?
Fred, Can you please provide a test that reproduces this concern
so we can verify the system behavior with and without my patch?
Benny
>
> Fred
> --
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next prev parent reply other threads:[~2013-03-27 12:19 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1363617532-24172-1-git-send-email-bhalevy@tonian.com>
2013-03-18 15:55 ` [PATCH] pnfs: do not reset to mds if wb_offset != wb_pgbase Myklebust, Trond
2013-03-18 16:22 ` Benny Halevy
2013-03-18 16:39 ` Myklebust, Trond
2013-03-18 16:45 ` Benny Halevy
2013-03-18 17:09 ` Myklebust, Trond
2013-03-18 17:04 ` Fred Isaman
2013-03-19 19:35 ` Benny Halevy
2013-03-19 20:28 ` Fred Isaman
2013-03-19 20:38 ` Benny Halevy
2013-03-27 12:19 ` Benny Halevy [this message]
2013-04-28 15:20 ` Benny Halevy
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