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Date:	Tue, 5 May 2015 10:21:45 -0400
From:	Theodore Ts'o <>
To:	"Darrick J. Wong" <>
Subject: Re: [PATCH 12/35] undo-io: use a bitmap to track what we've already

On Wed, Apr 01, 2015 at 07:35:19PM -0700, Darrick J. Wong wrote:
> It's really inefficient to (ab)use the TDB key store as a bitmap to
> find out if we've already written a block to the undo file, because
> the tdb code is reads the database key btree disk blocks for *every*
> query.  Changing that logic to a bitmap reduces overhead by a large
> margin -- the overhead of using undo_io while converting a 2TB FS to
> metadata_csum is reduced from 55 minutes to 45.
> Signed-off-by: Darrick J. Wong <>

Thanks, applied.

					- Ted
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