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/devpts/inode.c b/fs/devpts/inode.c
index c35ffdc..1f107fd 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -255,7 +255,7 @@
 	if (!uid_valid(root_uid) || !gid_valid(root_gid))
 		return -EINVAL;
 
-	mutex_lock(&d_inode(root)->i_mutex);
+	inode_lock(d_inode(root));
 
 	/* If we have already created ptmx node, return */
 	if (fsi->ptmx_dentry) {
@@ -292,7 +292,7 @@
 	fsi->ptmx_dentry = dentry;
 	rc = 0;
 out:
-	mutex_unlock(&d_inode(root)->i_mutex);
+	inode_unlock(d_inode(root));
 	return rc;
 }
 
@@ -615,7 +615,7 @@
 
 	sprintf(s, "%d", index);
 
-	mutex_lock(&d_inode(root)->i_mutex);
+	inode_lock(d_inode(root));
 
 	dentry = d_alloc_name(root, s);
 	if (dentry) {
@@ -626,7 +626,7 @@
 		inode = ERR_PTR(-ENOMEM);
 	}
 
-	mutex_unlock(&d_inode(root)->i_mutex);
+	inode_unlock(d_inode(root));
 
 	return inode;
 }
@@ -671,7 +671,7 @@
 
 	BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
 
-	mutex_lock(&d_inode(root)->i_mutex);
+	inode_lock(d_inode(root));
 
 	dentry = d_find_alias(inode);
 
@@ -680,7 +680,7 @@
 	dput(dentry);	/* d_alloc_name() in devpts_pty_new() */
 	dput(dentry);		/* d_find_alias above */
 
-	mutex_unlock(&d_inode(root)->i_mutex);
+	inode_unlock(d_inode(root));
 }
 
 static int __init init_devpts_fs(void)