From: jim owens <owens6336@gmail.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: linux-btrfs <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH V3 17/18] Btrfs: Full direct I/O and AIO read implementation.
Date: Thu, 25 Mar 2010 18:38:54 -0400 [thread overview]
Message-ID: <4BABE5FE.1000701@gmail.com> (raw)
In-Reply-To: <20100325094119.GJ20695@one.firstfloor.org>
Andi Kleen wrote:
> On Wed, Mar 24, 2010 at 11:08:07PM -0400, jim owens wrote:
>> Agree, so the write design needs to prevent bad checksums.
>
> How? Do you have a plan for that?
Yes... have Josef do it. ;)
The options I considered are:
1 - buffer always for uncompressed, the same as compressed.
2 - checksum before bio_add_page and again before page_cache_release
and fail or do buffering if checksum mismatch.
3 - write protect pages and block them in fault handler.
#3 is done in other operating systems but is painful, so I would
choose #2 because I think we can do more I/O that way at almost
the same cpu cost as #1 and we don't double the memory use.
jim
next prev parent reply other threads:[~2010-03-25 22:38 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-22 3:34 [PATCH V3 17/18] Btrfs: Full direct I/O and AIO read implementation jim owens
2010-03-23 5:49 ` Andi Kleen
2010-03-23 21:40 ` jim owens
2010-03-24 0:57 ` Chris Mason
2010-03-24 2:37 ` Andi Kleen
2010-03-25 3:08 ` jim owens
2010-03-25 9:41 ` Andi Kleen
2010-03-25 22:38 ` jim owens [this message]
2010-03-23 21:44 ` jim owens
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