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/reiserfs/ioctl.c b/fs/reiserfs/ioctl.c
index 6ec8a30..036a1fc 100644
--- a/fs/reiserfs/ioctl.c
+++ b/fs/reiserfs/ioctl.c
@@ -224,7 +224,7 @@
 	page_cache_release(page);
 
 out:
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 	reiserfs_write_unlock(inode->i_sb);
 	return retval;
 }