1 files changed, 12 insertions, 6 deletions

diff --git a/fs/jffs2/nodelist.c b/fs/jffs2/nodelist.c
index ac2a4c422e32..4bf86088b3ae 100644
--- a/fs/jffs2/nodelist.c
+++ b/fs/jffs2/nodelist.c
@@ -52,7 +52,7 @@ void jffs2_add_fd_to_list(struct jffs2_sb_info *c, struct jffs2_full_dirent *new
         *prev = new;
 }
 
-void jffs2_truncate_fragtree(struct jffs2_sb_info *c, struct rb_root *list, uint32_t size)
+uint32_t jffs2_truncate_fragtree(struct jffs2_sb_info *c, struct rb_root *list, uint32_t size)
 {
         struct jffs2_node_frag *frag = jffs2_lookup_node_frag(list, size);
 
@@ -74,18 +74,24 @@ void jffs2_truncate_fragtree(struct jffs2_sb_info *c, struct rb_root *list, uint
         }
 
         if (size == 0)
-                return;
+                return 0;
 
-        /*
-         * If the last fragment starts at the RAM page boundary, it is
-         * REF_PRISTINE irrespective of its size.
-         */
         frag = frag_last(list);
+
+        /* Sanity check for truncation to longer than we started with... */
+        if (!frag)
+                return 0;
+        if (frag->ofs + frag->size < size)
+                return frag->ofs + frag->size;
+
+        /* If the last fragment starts at the RAM page boundary, it is
+         * REF_PRISTINE irrespective of its size. */
         if (frag->node && (frag->ofs & (PAGE_CACHE_SIZE - 1)) == 0) {
                 dbg_fragtree2("marking the last fragment 0x%08x-0x%08x REF_PRISTINE.\n",
                         frag->ofs, frag->ofs + frag->size);
                 frag->node->raw->flash_offset = ref_offset(frag->node->raw) | REF_PRISTINE;
         }
+        return size;
 }
 
 static void jffs2_obsolete_node_frag(struct jffs2_sb_info *c,