linux-ext4 - double free of blocks occurred during online defrag

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Message-ID: <49A4E7B8.2040804@sx.jp.nec.com>
Date:	Wed, 25 Feb 2009 15:39:52 +0900
From:	Kazuya Mio <k-mio@...jp.nec.com>
To:	aneesh.kumar@...ux.vnet.ibm.com
CC:	linux-ext4@...r.kernel.org
Subject: double free of blocks occurred during online defrag

Hi Aneesh,

When I remove the file that is running online defrag, the following error occurs
after closing the file descriptor:

Jan 22 17:06:52 G3-OPC-SVR2 kernel: EXT4-fs error (device hda8):
ext4_mb_release_inode_pa: free 2048, pa_free 1562
Jan 22 17:06:52 G3-OPC-SVR2 kernel: EXT4-fs error (device hda8): mb_free_blocks:
double-free of inode 0's block 802817(bit 0 in group 98)
Jan 22 17:06:52 G3-OPC-SVR2 kernel: EXT4-fs error (device hda8): mb_free_blocks:
double-free of inode 0's block 802818(bit 1 in group 98)
Jan 22 17:06:52 G3-OPC-SVR2 kernel: EXT4-fs error (device hda8): mb_free_blocks:
double-free of inode 0's block 802819(bit 2 in group 98)
Jan 22 17:06:52 G3-OPC-SVR2 kernel: EXT4-fs error (device hda8): mb_free_blocks:
double-free of inode 0's block 802820(bit 3 in group 98)
Jan 22 17:06:52 G3-OPC-SVR2 kernel: EXT4-fs error (device hda8): mb_free_blocks:
double-free of inode 0's block 802821(bit 4 in group 98)
Jan 22 17:06:52 G3-OPC-SVR2 kernel: EXT4-fs error (device hda8): mb_free_blocks:
double-free of inode 0's block 802822(bit 5 in group 98)

So, online defrag calls ext4_discard_preallocations() at the end of
ext4_defrag() to avoid double-free error.
However, above error hasn't occurred since applying your patch posted on Nov
6th, 2008 because this error is caused by the same reason of your report.
http://marc.info/?l=linux-ext4&m=122599787406193&w=4

What is the status of this patch?

Regards,
Kazuya Mio
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