1 files changed, 25 insertions, 1 deletions

diff --git a/mm/z3fold.c b/mm/z3fold.c
index 98ab01f910bc..be8b56e21c2d 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -268,6 +268,7 @@ static inline void *mchunk_memmove(struct z3fold_header *zhdr,
                        zhdr->middle_chunks << CHUNK_SHIFT);
 }
 
+#define BIG_CHUNK_GAP   3
 /* Has to be called with lock held */
 static int z3fold_compact_page(struct z3fold_header *zhdr)
 {
@@ -286,8 +287,31 @@ static int z3fold_compact_page(struct z3fold_header *zhdr)
                 zhdr->middle_chunks = 0;
                 zhdr->start_middle = 0;
                 zhdr->first_num++;
+                return 1;
         }
-        return 1;
+
+        /*
+         * moving data is expensive, so let's only do that if
+         * there's substantial gain (at least BIG_CHUNK_GAP chunks)
+         */
+        if (zhdr->first_chunks != 0 && zhdr->last_chunks == 0 &&
+            zhdr->start_middle - (zhdr->first_chunks + ZHDR_CHUNKS) >=
+                        BIG_CHUNK_GAP) {
+                mchunk_memmove(zhdr, zhdr->first_chunks + ZHDR_CHUNKS);
+                zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
+                return 1;
+        } else if (zhdr->last_chunks != 0 && zhdr->first_chunks == 0 &&
+                   TOTAL_CHUNKS - (zhdr->last_chunks + zhdr->start_middle
+                                        + zhdr->middle_chunks) >=
+                        BIG_CHUNK_GAP) {
+                unsigned short new_start = TOTAL_CHUNKS - zhdr->last_chunks -
+                        zhdr->middle_chunks;
+                mchunk_memmove(zhdr, new_start);
+                zhdr->start_middle = new_start;
+                return 1;
+        }
+
+        return 0;
 }
 
 /**