locks: add missing memory barrier in break_deleg

[deliverable/linux.git] / include / linux / fs.h

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 878031227c57a0b41be7cde3070ee90f1921b570..22ae79650b82024c21c9901c15e3c58f3f0376fb 100644 (file)
--- 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;
@@ -2590,6 +2596,7 @@ extern ssize_t simple_read_from_buffer(void __user *to, size_t count,
 extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
                const void __user *from, size_t count);
 
+extern int __generic_file_fsync(struct file *, loff_t, loff_t, int);
 extern int generic_file_fsync(struct file *, loff_t, loff_t, int);
 
 extern int generic_check_addressable(unsigned, u64);