From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Neil Brown <neilb@suse.de>
Cc: Chris Mason <chris.mason@oracle.com>,
Nick Piggin <npiggin@suse.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>,
linux-fsdevel@vger.kernel.org
Subject: Re: [patch 1/3] add the fsblock layer
Date: Tue, 26 Jun 2007 13:07:43 +1000 [thread overview]
Message-ID: <468082FF.6090704@yahoo.com.au> (raw)
In-Reply-To: <18048.32372.40011.10896@notabene.brown>
Neil Brown wrote:
> On Tuesday June 26, nickpiggin@yahoo.com.au wrote:
>
>>Chris Mason wrote:
>>
>>>The block device pagecache isn't special, and certainly isn't that much
>>>code. I would suggest keeping it buffer head specific and making a
>>>second variant that does only fsblocks. This is mostly to keep the
>>>semantics of PagePrivate sane, lets not fuzz the line.
>>
>>That would require a new inode and address_space for the fsblock
>>type blockdev pagecache, wouldn't it? I just can't think of a
>>better non-intrusive way of allowing a buffer_head filesystem and
>>an fsblock filesystem to live on the same blkdev together.
>
>
> I don't think they would ever try to. Both filesystems would bd_claim
> the blkdev, and only one would win.
Hmm OK, I might have confused myself thinking about partitions...
> The issue is more of a filesystem sharing a blockdev with the
> block-special device (i.e. open("/dev/sda1"), read) isn't it?
>
> If a filesystem wants to attach information to the blockdev pagecache
> that is different to what blockdev want to attach, then I think "Yes"
> - a new inode and address space is what it needs to create.
>
> Then you get into consistency issues between the metadata and direct
> blockdevice access. Do we care about those?
Yeah that issue is definitely a real one. The problem is not just
consistency, but "how do the block device aops even know that the
PG_private page they have has buffer heads or fsblocks", so it is
an oopsable condition rather than just a plain consistency issue
(consistency is already not guaranteed).
--
SUSE Labs, Novell Inc.
next prev parent reply other threads:[~2007-06-26 3:07 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-24 1:45 [RFC] fsblock Nick Piggin
2007-06-24 1:46 ` [patch 1/3] add the fsblock layer Nick Piggin
2007-06-24 15:28 ` Andi Kleen
2007-06-24 20:18 ` Arjan van de Ven
2007-06-25 8:58 ` Andi Kleen
2007-06-25 7:19 ` Nick Piggin
2007-06-24 23:01 ` Neil Brown
2007-06-25 7:41 ` Nick Piggin
2007-06-25 12:29 ` Chris Mason
2007-06-26 2:34 ` Nick Piggin
2007-06-26 2:48 ` Neil Brown
2007-06-26 3:07 ` Nick Piggin [this message]
2007-06-26 12:26 ` Chris Mason
2007-06-30 10:40 ` Christoph Hellwig
2007-06-30 10:40 ` Christoph Hellwig
2007-06-25 13:19 ` Chris Mason
2007-06-26 2:42 ` Nick Piggin
2007-06-24 1:46 ` [patch 2/3] block_dev: convert to fsblock Nick Piggin
2007-06-24 1:47 ` [patch 3/3] minix: " Nick Piggin
2007-06-24 1:53 ` [RFC] fsblock Nick Piggin
2007-06-24 3:07 ` Jeff Garzik
2007-06-24 3:47 ` Nick Piggin
2007-06-24 13:51 ` Chris Mason
2007-06-25 6:58 ` Nick Piggin
2007-06-25 12:25 ` Chris Mason
2007-06-30 10:44 ` Christoph Hellwig
2007-06-30 10:42 ` Christoph Hellwig
2007-06-30 11:10 ` Jeff Garzik
2007-06-30 11:13 ` Christoph Hellwig
2007-06-24 4:19 ` William Lee Irwin III
2007-06-24 14:16 ` Andi Kleen
2007-06-25 7:16 ` Nick Piggin
2007-06-26 3:06 ` David Chinner
2007-06-26 3:55 ` Nick Piggin
2007-06-26 9:23 ` David Chinner
2007-06-26 11:14 ` Nick Piggin
2007-06-27 12:39 ` Kyle Moffett
2007-06-26 12:34 ` Chris Mason
2007-06-27 5:32 ` Nick Piggin
2007-06-27 6:05 ` David Chinner
2007-06-27 11:50 ` Chris Mason
2007-06-27 15:18 ` Anton Altaparmakov
2007-06-27 22:35 ` David Chinner
2007-06-28 2:44 ` Nick Piggin
2007-06-28 12:20 ` Chris Mason
2007-06-29 2:08 ` David Chinner
2007-06-29 2:33 ` Nick Piggin
2007-06-30 11:05 ` Christoph Hellwig
2007-07-09 17:14 ` Christoph Lameter
2007-07-10 0:54 ` Nick Piggin
2007-07-10 0:59 ` Christoph Lameter
2007-07-10 1:07 ` Nick Piggin
2007-07-10 1:37 ` Dave McCracken
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