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From: McPacino <mcpacino@gmail.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Daniel Phillips <phillips@phunq.net>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	dm-devel@redhat.com, Andrew Morton <akpm@linux-foundation.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Nick Piggin <npiggin@kernel.dk>
Subject: Re: introduce dm-snap-mv
Date: Fri, 8 Oct 2010 17:14:27 +0800	[thread overview]
Message-ID: <AANLkTim9KFuP1_mrUUsMOEspxkfA=SZW2dmTX4WJbfep@mail.gmail.com> (raw)
In-Reply-To: <20101008082231.GA2054@lst.de>

Hi Christoph,

I have to take care the cache problem If using the bio directly.
BHs can be released by kernel when necessary.

Is there any existing code using bio to read/write metadata
blocks? How do they handle the timing freeing bios? I really
wish to learn something form it.

Regards.

Cong Meng.



On Fri, Oct 8, 2010 at 4:22 PM, Christoph Hellwig <hch@lst.de> wrote:
> On Thu, Oct 07, 2010 at 02:31:14PM -0700, Daniel Phillips wrote:
>> Hi Meng,
>>
>> The patch looks sensible, however the question is: why do you want to
>> do this?  Would it not be better to generalize your metadata format to
>> accomodate the device's native blocksize?
>
> Even if it uses fixed 4k sectors it should just read them in smaller
> chunks OR even better stop using buffer heads and just read them
> manually using submit_bio.  BHs really shouldn't be used outside of
> filesystems, and even there they slowly are on their way out.
>
>

  reply	other threads:[~2010-10-08  9:14 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-06  8:31 introduce dm-snap-mv Cong Meng
2010-10-07 21:31 ` Daniel Phillips
2010-10-08  8:22   ` Christoph Hellwig
2010-10-08  9:14     ` McPacino [this message]
2010-10-08  9:24       ` Christoph Hellwig
2010-10-08  9:28         ` McPacino
2010-10-08 13:22         ` Daniel Phillips
2010-10-13 16:45         ` McPacino
2010-10-08  9:01   ` McPacino
2010-10-19 19:58 ` [dm-devel] " Mikulas Patocka
2010-11-06  3:24   ` Daniel Phillips

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