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@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
--
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