linux-ext4 - Re: [PATCH] libext2fs: reset handle after inserting new extent

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Date:	Tue, 7 Jul 2009 09:35:07 -0400
From:	Theodore Tso <tytso@....edu>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] libext2fs: reset handle after inserting new extent

On Mon, Jul 06, 2009 at 05:15:07PM -0500, Eric Sandeen wrote:
> Commit 53422e8a5644e22ea3f6e0efba82a765b72e4308 moved
> the new extent insertion in ext2fs_extent_set_bmap prior
> to the modification of the original extent, but the
> insert function left the handle pointing a the new
> extent; this left us modifying the -new- extent not
> the original one, and winding up with a corrupt extent
> tree something like:
> 
> BLOCKS:
> (0-1):588791-588792, (0):588791
> 
> We need to move back to the previous extent prior
> to modification, if we inserted a new one.

Hmm, I just thought of something awful; what if the insert resulted in
a node split?  Instead of using ext2fs_extent_get(EXT2_EXTENT_PREV),
we may need to use ext2fs_extent_goto() to seek to the correct logical
block instead.

						- Ted
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