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

From: Luis Henriques
Date: Mon Jun 17 2013 - 06:18:30 EST


Ben Hutchings <ben@xxxxxxxxxxxxxxx> writes:

> 3.2.47-rc1 review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Theodore Ts'o <tytso@xxxxxxx>
>
> commit 721e3eba21e43532e438652dd8f1fcdfce3187e7 upstream.

I'm also queuing this commit as it looks like 3.5 is also missing it.

Cheers,
--
Luis

>
> 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);
> ext4_truncate(inode);
> + mutex_unlock(&inode->i_mutex);
> nr_truncates++;
> } else {
> ext4_msg(sb, KERN_DEBUG,
>
> --
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