From: Akira Fujita <a-fujita@rs.jp.nec.com>
Date: Wed, 16 Sep 2009 18:25:39 +0000 (-0400)
Subject: ext4: Fix different block exchange issue in EXT4_IOC_MOVE_EXT
X-Git-Tag: v2.6.32-rc1~633^2~6
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c40ce3c9ea97425a12d7e44031a98fe50add6fc1;p=pandora-kernel.git

ext4: Fix different block exchange issue in EXT4_IOC_MOVE_EXT

If logical block offset of original file which is passed to
EXT4_IOC_MOVE_EXT is different from donor file's,
a calculation error occurs in ext4_calc_swap_extents(),
therefore wrong block is exchanged between original file and donor file.
As a result, we hit ext4_error() in check_block_validity().
To detect the logical offset difference in EXT4_IOC_MOVE_EXT,
add checks to mext_calc_swap_extents() and handle it as error,
since data exchange must be done between the same blocks in EXT4_IOC_MOVE_EXT.

Reported-by: Peng Tao <bergwolf@gmail.com>
Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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