migration: introduce control_save_page()

Abstract the common function control_save_page() to cleanup the code,
no logic is changed

Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
Message-Id: <20180330075128.26919-6-xiaoguangrong@tencent.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

migration/ram.c

@@ -974,6 +974,44 @@ static void ram_release_pages(const char *rbname, uint64_t offset, int pages)
     ram_discard_range(rbname, offset, pages << TARGET_PAGE_BITS);
 }
 
+/*
+ * @pages: the number of pages written by the control path,
+ *        < 0 - error
+ *        > 0 - number of pages written
+ *
+ * Return true if the pages has been saved, otherwise false is returned.
+ */
+static bool control_save_page(RAMState *rs, RAMBlock *block, ram_addr_t offset,
+                              int *pages)
+{
+    uint64_t bytes_xmit = 0;
+    int ret;
+
+    *pages = -1;
+    ret = ram_control_save_page(rs->f, block->offset, offset, TARGET_PAGE_SIZE,
+                                &bytes_xmit);
+    if (ret == RAM_SAVE_CONTROL_NOT_SUPP) {
+        return false;
+    }
+
+    if (bytes_xmit) {
+        ram_counters.transferred += bytes_xmit;
+        *pages = 1;
+    }
+
+    if (ret == RAM_SAVE_CONTROL_DELAYED) {
+        return true;
+    }
+
+    if (bytes_xmit > 0) {
+        ram_counters.normal++;
+    } else if (bytes_xmit == 0) {
+        ram_counters.duplicate++;
+    }
+
+    return true;
+}
+
 /**
  * ram_save_page: send the given page to the stream
  *
@@ -990,39 +1028,20 @@ static void ram_release_pages(const char *rbname, uint64_t offset, int pages)
 static int ram_save_page(RAMState *rs, PageSearchStatus *pss, bool last_stage)
 {
     int pages = -1;
-    uint64_t bytes_xmit;
-    ram_addr_t current_addr;
     uint8_t *p;
-    int ret;
     bool send_async = true;
     RAMBlock *block = pss->block;
     ram_addr_t offset = pss->page << TARGET_PAGE_BITS;
+    ram_addr_t current_addr = block->offset + offset;
 
     p = block->host + offset;
     trace_ram_save_page(block->idstr, (uint64_t)offset, p);
 
-    /* In doubt sent page as normal */
+    if (control_save_page(rs, block, offset, &pages)) {
-    bytes_xmit = 0;
+        return pages;
-    ret = ram_control_save_page(rs->f, block->offset,
-                           offset, TARGET_PAGE_SIZE, &bytes_xmit);
-    if (bytes_xmit) {
-        ram_counters.transferred += bytes_xmit;
-        pages = 1;
     }
 
     XBZRLE_cache_lock();
-
-    current_addr = block->offset + offset;
-
-    if (ret != RAM_SAVE_CONTROL_NOT_SUPP) {
-        if (ret != RAM_SAVE_CONTROL_DELAYED) {
-            if (bytes_xmit > 0) {
-                ram_counters.normal++;
-            } else if (bytes_xmit == 0) {
-                ram_counters.duplicate++;
-            }
-        }
-    } else {
     pages = save_zero_page(rs, block, offset);
     if (pages > 0) {
         /* Must let xbzrle know, otherwise a previous (now 0'd) cached
@@ -1041,7 +1060,6 @@ static int ram_save_page(RAMState *rs, PageSearchStatus *pss, bool last_stage)
             send_async = false;
         }
     }
-    }
 
     /* XBZRLE overflow or normal page */
     if (pages == -1) {
@@ -1174,29 +1192,16 @@ static int ram_save_compressed_page(RAMState *rs, PageSearchStatus *pss,
                                     bool last_stage)
 {
     int pages = -1;
-    uint64_t bytes_xmit = 0;
     uint8_t *p;
-    int ret;
     RAMBlock *block = pss->block;
     ram_addr_t offset = pss->page << TARGET_PAGE_BITS;
 
     p = block->host + offset;
 
-    ret = ram_control_save_page(rs->f, block->offset,
+    if (control_save_page(rs, block, offset, &pages)) {
-                                offset, TARGET_PAGE_SIZE, &bytes_xmit);
+        return pages;
-    if (bytes_xmit) {
-        ram_counters.transferred += bytes_xmit;
-        pages = 1;
     }
-    if (ret != RAM_SAVE_CONTROL_NOT_SUPP) {
+
-        if (ret != RAM_SAVE_CONTROL_DELAYED) {
-            if (bytes_xmit > 0) {
-                ram_counters.normal++;
-            } else if (bytes_xmit == 0) {
-                ram_counters.duplicate++;
-            }
-        }
-    } else {
     /* When starting the process of a new block, the first page of
      * the block should be sent out before other pages in the same
      * block, and all the pages in last block should have been sent
@@ -1232,7 +1237,6 @@ static int ram_save_compressed_page(RAMState *rs, PageSearchStatus *pss,
             ram_release_pages(block->idstr, offset, pages);
         }
     }
-    }
 
     return pages;
 }