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/quota_global.c b/fs/ocfs2/quota_global.c
index fde9ef1..9c9dd30 100644
--- a/fs/ocfs2/quota_global.c
+++ b/fs/ocfs2/quota_global.c
@@ -308,7 +308,7 @@
 		WARN_ON(bh != oinfo->dqi_gqi_bh);
 	spin_unlock(&dq_data_lock);
 	if (ex) {
-		mutex_lock(&oinfo->dqi_gqinode->i_mutex);
+		inode_lock(oinfo->dqi_gqinode);
 		down_write(&OCFS2_I(oinfo->dqi_gqinode)->ip_alloc_sem);
 	} else {
 		down_read(&OCFS2_I(oinfo->dqi_gqinode)->ip_alloc_sem);
@@ -320,7 +320,7 @@
 {
 	if (ex) {
 		up_write(&OCFS2_I(oinfo->dqi_gqinode)->ip_alloc_sem);
-		mutex_unlock(&oinfo->dqi_gqinode->i_mutex);
+		inode_unlock(oinfo->dqi_gqinode);
 	} else {
 		up_read(&OCFS2_I(oinfo->dqi_gqinode)->ip_alloc_sem);
 	}