UBIFS: increment commit number earlier

Increment the commit number at the beginnig of the commit, instead
of doing this after the commit. This is needed for further
optimizations.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/fs/ubifs/log.c b/fs/ubifs/log.c
index e14829e..3e0aa73 100644
--- a/fs/ubifs/log.c
+++ b/fs/ubifs/log.c
@@ -412,7 +412,7 @@
 		return -ENOMEM;
 
 	cs->ch.node_type = UBIFS_CS_NODE;
-	cs->cmt_no = cpu_to_le64(c->cmt_no + 1);
+	cs->cmt_no = cpu_to_le64(c->cmt_no);
 	ubifs_prepare_node(c, cs, UBIFS_CS_NODE_SZ, 0);
 
 	/*