vfs, freeze: use ACCESS_ONCE() to guard access to ->mnt_flags

The compiler may optimize the while loop and make the check just be done once, so we should use ACCESS_ONCE() to guard access to ->mnt_flags Signed-off-by: Miao Xie <[email protected]> Signed-off-by: Al Viro <[email protected]>
kyagi · Dec 20, 2012 · 1e75529 · 1e75529
1 parent f01af9f
commit 1e75529
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/fs/namespace.c b/fs/namespace.c
@@ -313,7 +313,7 @@ int __mnt_want_write(struct vfsmount *m)
 	 * incremented count after it has set MNT_WRITE_HOLD.
 	 */
 	smp_mb();
-	while (mnt->mnt.mnt_flags & MNT_WRITE_HOLD)
+	while (ACCESS_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD)
 		cpu_relax();
 	/*
 	 * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will