fs/namespace.c: allow to drop vfsmount references via __free(mntput)

Note that just as path_put, it should never be done in scope of
namespace_sem, be it shared or exclusive.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namespace.c b/fs/namespace.c
index fcea65587ff9146ae296eaa72d2f9cbccf375abd..767ab751ee2a392f51cd7a757144a854d1fb7aae 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -88,6 +88,8 @@ DEFINE_LOCK_GUARD_0(namespace_excl, namespace_lock(), namespace_unlock())
 DEFINE_LOCK_GUARD_0(namespace_shared, down_read(&namespace_sem),
                                      up_read(&namespace_sem))
 
+DEFINE_FREE(mntput, struct vfsmount *, if (!IS_ERR(_T)) mntput(_T))
+
 #ifdef CONFIG_FSNOTIFY
 LIST_HEAD(notify_list); /* protected by namespace_sem */
 #endif