wrappers for ->i_mutex access

parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/proc/self.c b/fs/proc/self.c
index 67e8db4..b6a8d35 100644
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -50,7 +50,7 @@
 	struct pid_namespace *ns = s->s_fs_info;
 	struct dentry *self;
 	
-	mutex_lock(&root_inode->i_mutex);
+	inode_lock(root_inode);
 	self = d_alloc_name(s->s_root, "self");
 	if (self) {
 		struct inode *inode = new_inode_pseudo(s);
@@ -69,7 +69,7 @@
 	} else {
 		self = ERR_PTR(-ENOMEM);
 	}
-	mutex_unlock(&root_inode->i_mutex);
+	inode_unlock(root_inode);
 	if (IS_ERR(self)) {
 		pr_err("proc_fill_super: can't allocate /proc/self\n");
 		return PTR_ERR(self);