linux-ext4 - Re: [PATCH 2/2] e2fsck: fix e2fsck -fD directory truncation

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Date:	Mon, 30 Nov 2015 15:29:52 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	Andreas Dilger <andreas.dilger@...el.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 2/2] e2fsck: fix e2fsck -fD directory truncation

On Thu, Nov 19, 2015 at 01:13:19AM -0700, Andreas Dilger wrote:
> When an extent-mapped directory is compacted by "e2fsck -fD" and
> frees enough leaf blocks that it loses an extent tree index block,
> the old e2fsck_rehash_dir->ext2fs_block_iterate3->write_dir_block()
> code would not free the extent block, which would result in the
> extent tree becoming corrupted when it is written out.
> 
>     Pass 1: Checking inodes, blocks, and sizes
>     Inode 17825800, end of extent exceeds allowed value
>             (logical block 710, physical block 570459684, len 1019)
> 
> This results in loss of a whole index block of directory leaf blocks
> and maybe thousands or millions of files in lost+found.
> 
> Fix e2fsck_rehash_dir() to call ext2fs_punch() to free the blocks
> at the end of the directory instead of trying to handle this itself
> while writing out the directory.  That properly handles all of the
> cases of updating the extent tree as well as accounting for blocks
> that are released (both leaf blocks and index blocks).
> 
> Add a test case for compacting the directory to be smaller than the
> index block that originally caused the corruption.
> 
> Signed-off-by: Andreas Dilger <andreas.dilger@...el.com>

Thanks, applied.

						- Ted
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