From: Akira Fujita <a-fujita@rs.jp.nec.com>
Date: Mon, 23 Nov 2009 12:24:41 +0000 (-0500)
Subject: ext4: fix possible recursive locking warning in EXT4_IOC_MOVE_EXT
X-Git-Tag: v2.6.33-rc1~330^2~42
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=49bd22bc4d603a2a4fc2a6a60e156cbea52eb494;p=pandora-kernel.git

ext4: fix possible recursive locking warning in EXT4_IOC_MOVE_EXT

If CONFIG_PROVE_LOCKING is enabled, the double_down_write_data_sem()
will trigger a false-positive warning of a recursive lock.  Since we
take i_data_sem for the two inodes ordered by their inode numbers,
this isn't a problem.  Use of down_write_nested() will notify the lock
dependency checker machinery that there is no problem here.

This problem was reported by Brian Rogers:

	http://marc.info/?l=linux-ext4&m=125115356928011&w=1

Reported-by: Brian Rogers <brian@xyzw.org>
Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

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