Messages in this thread Patch in this message | | | Date | Thu, 10 Dec 2009 21:23:21 -0800 | From | Greg KH <> | Subject | [09/34] ext4: fix possible recursive locking warning in EXT4_IOC_MOVE_EXT |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
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(cherry picked from commit 49bd22bc4d603a2a4fc2a6a60e156cbea52eb494)
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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- fs/ext4/move_extent.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/ext4/move_extent.c +++ b/fs/ext4/move_extent.c @@ -189,7 +189,7 @@ double_down_write_data_sem(struct 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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