[ 113/221] ext4: lock i_mutex when truncating orphan inodes

Greg Kroah-Hartman
2013-01-15T22:31:48Z

From: Theodore Ts'o <tytso@mit.edu>

commit 721e3eba21e43532e438652dd8f1fcdfce3187e7 upstream.

Commit c278531d39 added a warning when ext4_flush_unwritten_io() is
called without i_mutex being taken. It had previously not been taken
during orphan cleanup since races weren't possible at that point in
the mount process, but as a result of this c278531d39, we will now see
a kernel WARN_ON in this case. Take the i_mutex in
ext4_orphan_cleanup() to suppress this warning.

Reported-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ext4/super.c | 2 ++
1 file changed, 2 insertions(+)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2225,7 +2225,9 @@ static void ext4_orphan_cleanup(struct s
__func__, inode->i_ino, inode->i_size);
jbd_debug(2, "truncating inode %lu to %lld bytes\n",
inode->i_ino, inode->i_size);
+ mutex_lock(&inode->i_mutex);
ext4_truncate(inode);
+ mutex_unlock(&inode->i_mutex);
nr_truncates++;
} else {
ext4_msg(sb, KERN_DEBUG,