On 5/9/11 10:57 AM, Lukas Czerner wrote:
> We need to take reference to the s_li_request after we take a mutex,
> because it might be freed since then, hence result in accessing old
> already freed memory. Also we should protect the whole
> ext4_remove_li_request() because ext4_li_info might be in the process of
> being freed in ext4_lazyinit_thread().
It'd be really great to have some comments which explain just what
ext4_li_mtx protects, but I'm working on an add-comments patch for
the lazyinit stuff (I commented things a bit as I reviewed your
changes) so I'll send that along later.
in any case, the change looks ok, thanks.
Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx>
> ---
> fs/ext4/super.c | 10 ++++++----
> 1 files changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index c379af6..6a8e48f 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -2721,14 +2721,16 @@ static void ext4_remove_li_request(struct ext4_li_request *elr)
>
> static void ext4_unregister_li_request(struct super_block *sb)
> {
> - struct ext4_li_request *elr = EXT4_SB(sb)->s_li_request;
> -
> - if (!ext4_li_info)
> + mutex_lock(&ext4_li_mtx);
> + if (!ext4_li_info) {
> + mutex_unlock(&ext4_li_mtx);
> return;
> + }
>
> mutex_lock(&ext4_li_info->li_list_mtx);
> - ext4_remove_li_request(elr);
> + ext4_remove_li_request(EXT4_SB(sb)->s_li_request);
> mutex_unlock(&ext4_li_info->li_list_mtx);
> + mutex_unlock(&ext4_li_mtx);
> }
>
> static struct task_struct *ext4_lazyinit_task;
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