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/ocfs2/dir.c b/fs/ocfs2/dir.c
index ffecf89..e1adf28 100644
--- a/fs/ocfs2/dir.c
+++ b/fs/ocfs2/dir.c
@@ -4361,7 +4361,7 @@
 		mlog_errno(ret);
 		goto out;
 	}
-	mutex_lock(&dx_alloc_inode->i_mutex);
+	inode_lock(dx_alloc_inode);
 
 	ret = ocfs2_inode_lock(dx_alloc_inode, &dx_alloc_bh, 1);
 	if (ret) {
@@ -4410,7 +4410,7 @@
 	ocfs2_inode_unlock(dx_alloc_inode, 1);
 
 out_mutex:
-	mutex_unlock(&dx_alloc_inode->i_mutex);
+	inode_unlock(dx_alloc_inode);
 	brelse(dx_alloc_bh);
 out:
 	iput(dx_alloc_inode);