migration: Move ram_release_pages() call to save_zero_page_to_file()

We always need to call it when we find a zero page, so put it in a
single place.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>

migration/ram.c

@@ -1158,6 +1158,15 @@ static void migration_bitmap_sync_precopy(RAMState *rs)
     }
 }
 
+static void ram_release_page(const char *rbname, uint64_t offset)
+{
+    if (!migrate_release_ram() || !migration_in_postcopy()) {
+        return;
+    }
+
+    ram_discard_range(rbname, offset, TARGET_PAGE_SIZE);
+}
+
 /**
  * save_zero_page_to_file: send the zero page to the file
  *
@@ -1179,6 +1188,7 @@ static int save_zero_page_to_file(RAMState *rs, QEMUFile *file,
         len += save_page_header(rs, file, block, offset | RAM_SAVE_FLAG_ZERO);
         qemu_put_byte(file, 0);
         len += 1;
+        ram_release_page(block->idstr, offset);
     }
     return len;
 }
@@ -1204,15 +1214,6 @@ static int save_zero_page(RAMState *rs, RAMBlock *block, ram_addr_t offset)
     return -1;
 }
 
-static void ram_release_page(const char *rbname, uint64_t offset)
-{
-    if (!migrate_release_ram() || !migration_in_postcopy()) {
-        return;
-    }
-
-    ram_discard_range(rbname, offset, TARGET_PAGE_SIZE);
-}
-
 /*
  * @pages: the number of pages written by the control path,
  *        < 0 - error
@@ -1344,7 +1345,6 @@ static bool do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block,
     int ret;
 
     if (save_zero_page_to_file(rs, f, block, offset)) {
-        ram_release_page(block->idstr, offset);
         return true;
     }
 
@@ -2148,7 +2148,6 @@ static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss)
             xbzrle_cache_zero_page(rs, block->offset + offset);
             XBZRLE_cache_unlock();
         }
-        ram_release_page(block->idstr, offset);
         return res;
     }