On Tue, Jun 10, 2014 at 04:14:35PM -0400, Jeff Layton wrote:
> break_deleg is subject to the same potential race as break_lease. Add
> a memory barrier to prevent it.
Acked-by: J. Bruce Fields <bfields@xxxxxxxxxx>
Though we might now just move the comment, smp_mb(), and inode->i_flock
calls into __break_lease?
--b.
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
> ---
> include/linux/fs.h | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index c3f46e499dd0..22ae79650b82 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1914,6 +1914,12 @@ static inline int break_lease(struct inode *inode, unsigned int mode)
>
> static inline int break_deleg(struct inode *inode, unsigned int mode)
> {
> + /*
> + * Since this check is lockless, we must ensure that any refcounts
> + * taken are done before checking inode->i_flock. Otherwise, we could
> + * end up racing with tasks trying to set a new lease on this file.
> + */
> + smp_mb();
> if (inode->i_flock)
> return __break_lease(inode, mode, FL_DELEG);
> return 0;
> --
> 1.9.3
>
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
