[28/83] ext4: lock i_mutex when truncating orphan inodes

From: Ben Hutchings
Date: Sun Jun 16 2013 - 18:21:16 EST

3.2.47-rc1 review patch. If anyone has any objections, please let me know.


From: Theodore Ts'o <tytso@xxxxxxx>

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@xxxxxxxxx>
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
Reviewed-by: Zheng Liu <wenqing.lz@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
fs/ext4/super.c | 2 ++
1 file changed, 2 insertions(+)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2260,7 +2260,9 @@ 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);
+ mutex_unlock(&inode->i_mutex);
} else {
ext4_msg(sb, KERN_DEBUG,

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