Commit 49bd22bc authored Nov 23, 2009 by Akira Fujita Committed by Theodore Ts'o Nov 23, 2009

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>

parent fc04cb49

fs/ext4/move_extent.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -189,7 +189,7 @@ double_down_write_data_sem(struct inode orig_inode, struct inode donor_inode)
		}

		down_write(&EXT4_I(first)->i_data_sem);
		down_write(&EXT4_I(second)->i_data_sem);
		down_write_nested(&EXT4_I(second)->i_data_sem, SINGLE_DEPTH_NESTING);
		}

		/**

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