VFS: Remove dependency of ->umount_begin() call on MNT_FORCE

Allow filesystems to decide to perform pre-umount processing whether or not
MNT_FORCE is set.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/9p/vfs_super.c b/fs/9p/vfs_super.c
index 61c599b..00c1f6b 100644
--- a/fs/9p/vfs_super.c
+++ b/fs/9p/vfs_super.c
@@ -253,11 +253,12 @@
 }
 
 static void
-v9fs_umount_begin(struct super_block *sb)
+v9fs_umount_begin(struct vfsmount *vfsmnt, int flags)
 {
-	struct v9fs_session_info *v9ses = sb->s_fs_info;
+	struct v9fs_session_info *v9ses = vfsmnt->mnt_sb->s_fs_info;
 
-	v9fs_session_cancel(v9ses);
+	if (flags & MNT_FORCE)
+		v9fs_session_cancel(v9ses);
 }
 
 static struct super_operations v9fs_super_ops = {