From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Chinner <dgc@sgi.com>
Subject: Re: [RFC] fsblock
Date: Wed, 27 Jun 2007 16:05:31 +1000
Message-ID: <20070627060531.GV31489@sgi.com>
References: <20070624014528.GA17609@wotan.suse.de> <20070626030640.GM989688@sgi.com> <46808E1F.1000509@yahoo.com.au> <20070626092309.GF31489@sgi.com> <20070626123449.GM14224@think.oraclecorp.com> <20070627053245.GA6033@wotan.suse.de>
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Cc: Chris Mason <chris.mason@oracle.com>, David Chinner <dgc@sgi.com>,
	Nick Piggin <nickpiggin@yahoo.com.au>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Memory Management List <linux-mm@kvack.org>,
	linux-fsdevel@vger.kernel.org
To: Nick Piggin <npiggin@suse.de>
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On Wed, Jun 27, 2007 at 07:32:45AM +0200, Nick Piggin wrote:
> I think using fsblock to drive the IO and keep the pagecache flags
> uptodate and using a btree in the filesystem to manage extents of block
> allocations wouldn't be a bad idea though. Do any filesystems actually
> do this?

Yes. XFS. But we still need to hold state in buffer heads (BH_delay,
BH_unwritten) that is needed to determine what type of
allocation/extent conversion is necessary during writeback. i.e.
what we originally mapped the page as during the ->prepare_write
call.

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group