tree b1a8d6b5be2ff4a72f2274bf01c15922ad9a0e65
parent fc04cb49a898c372a22b21fffc47f299d8710801
author Akira Fujita <a-fujita@rs.jp.nec.com> 1258979081 -0500
committer Theodore Ts'o <tytso@mit.edu> 1258979081 -0500

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>