locks: add missing memory barrier in break_deleg
break_deleg is subject to the same potential race as break_lease. Add
a memory barrier to prevent it.
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c3f46e4..22ae796 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1914,6 +1914,12 @@
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;