[JFFS2] Correct handling of JFFS2_FEATURE_RWCOMPAT_COPY nodes.

We should preserve these when we come to garbage collect them, not let
them get erased. Use jffs2_garbage_collect_pristine() for this, and make
sure the summary code copes -- just refrain from writing a summary for any
block which contains a node we don't understand.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
diff --git a/fs/jffs2/nodelist.h b/fs/jffs2/nodelist.h
index bac4ec3..1f5d5b0 100644
--- a/fs/jffs2/nodelist.h
+++ b/fs/jffs2/nodelist.h
@@ -97,6 +97,11 @@
 #define ref_obsolete(ref)	(((ref)->flash_offset & 3) == REF_OBSOLETE)
 #define mark_ref_normal(ref)    do { (ref)->flash_offset = ref_offset(ref) | REF_NORMAL; } while(0)
 
+/* NB: REF_PRISTINE for an inode-less node (ref->next_in_ino == NULL) indicates
+   it is an unknown node of type JFFS2_NODETYPE_RWCOMPAT_COPY, so it'll get
+   copied. If you need to do anything different to GC inode-less nodes, then
+   you need to modify gc.c accordingly. */
+
 /* For each inode in the filesystem, we need to keep a record of
    nlink, because it would be a PITA to scan the whole directory tree
    at read_inode() time to calculate it, and to keep sufficient information