It makes a bit more sense to have the zero page handling of xbzrle
right where we save the zero page.

This also makes save_zero_page() follow the same format as
save_compress_page() at the top level of
ram_save_target_page_legacy().

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/ram.c | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/migration/ram.c b/migration/ram.c
index 761f43dc34..a10410a1a5 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1159,11 +1159,12 @@ static int save_zero_page_to_file(PageSearchStatus *pss, RAMBlock *block,
  *
  * Returns the number of pages written.
  *
+ * @rs: current RAM state
  * @pss: current PSS channel
  * @block: block that contains the page we want to send
  * @offset: offset inside the block for the page
  */
-static int save_zero_page(PageSearchStatus *pss, RAMBlock *block,
+static int save_zero_page(RAMState *rs, PageSearchStatus *pss, RAMBlock *block,
                           ram_addr_t offset)
 {
     int len = save_zero_page_to_file(pss, block, offset);
@@ -1171,6 +1172,17 @@ static int save_zero_page(PageSearchStatus *pss, RAMBlock *block,
     if (len) {
         stat64_add(&mig_stats.zero_pages, 1);
         ram_transferred_add(len);
+
+        /*
+         * Must let xbzrle know, otherwise a previous (now 0'd) cached
+         * page would be stale.
+         */
+        if (rs->xbzrle_started) {
+            XBZRLE_cache_lock();
+            xbzrle_cache_zero_page(block->offset + offset);
+            XBZRLE_cache_unlock();
+        }
+
         return 1;
     }
     return -1;
@@ -2141,17 +2153,8 @@ static int ram_save_target_page_legacy(RAMState *rs, PageSearchStatus *pss)
         return 1;
     }
 
-    res = save_zero_page(pss, block, offset);
-    if (res > 0) {
-        /* Must let xbzrle know, otherwise a previous (now 0'd) cached
-         * page would be stale
-         */
-        if (rs->xbzrle_started) {
-            XBZRLE_cache_lock();
-            xbzrle_cache_zero_page(block->offset + offset);
-            XBZRLE_cache_unlock();
-        }
-        return res;
+    if (save_zero_page(rs, pss, block, offset)) {
+        return 1;
     }
 
     /*
-- 
2.35.3

Fabiano Rosas <farosas@suse.de> writes:

> It makes a bit more sense to have the zero page handling of xbzrle
> right where we save the zero page.
>
> This also makes save_zero_page() follow the same format as
> save_compress_page() at the top level of
> ram_save_target_page_legacy().
>
> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> ---
>  migration/ram.c | 27 +++++++++++++++------------
>  1 file changed, 15 insertions(+), 12 deletions(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index 761f43dc34..a10410a1a5 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -1159,11 +1159,12 @@ static int save_zero_page_to_file(PageSearchStatus *pss, RAMBlock *block,
>   *
>   * Returns the number of pages written.
>   *
> + * @rs: current RAM state
>   * @pss: current PSS channel
>   * @block: block that contains the page we want to send
>   * @offset: offset inside the block for the page
>   */
> -static int save_zero_page(PageSearchStatus *pss, RAMBlock *block,
> +static int save_zero_page(RAMState *rs, PageSearchStatus *pss, RAMBlock *block,
>                            ram_addr_t offset)
>  {
>      int len = save_zero_page_to_file(pss, block, offset);
> @@ -1171,6 +1172,17 @@ static int save_zero_page(PageSearchStatus *pss, RAMBlock *block,
>      if (len) {
>          stat64_add(&mig_stats.zero_pages, 1);
>          ram_transferred_add(len);
> +
> +        /*
> +         * Must let xbzrle know, otherwise a previous (now 0'd) cached
> +         * page would be stale.
> +         */
> +        if (rs->xbzrle_started) {
> +            XBZRLE_cache_lock();
> +            xbzrle_cache_zero_page(block->offset + offset);
> +            XBZRLE_cache_unlock();
> +        }
> +
>          return 1;
>      }
>      return -1;
> @@ -2141,17 +2153,8 @@ static int ram_save_target_page_legacy(RAMState *rs, PageSearchStatus *pss)
>          return 1;
>      }
>  
> -    res = save_zero_page(pss, block, offset);
> -    if (res > 0) {

These two subtractions should be in patch 5.

> -        /* Must let xbzrle know, otherwise a previous (now 0'd) cached
> -         * page would be stale
> -         */
> -        if (rs->xbzrle_started) {
> -            XBZRLE_cache_lock();
> -            xbzrle_cache_zero_page(block->offset + offset);
> -            XBZRLE_cache_unlock();
> -        }
> -        return res;
> +    if (save_zero_page(rs, pss, block, offset)) {
> +        return 1;

These two additions should be in patch 5.

>      }
>  
>      /*

On Tue, Aug 15, 2023 at 11:38:26AM -0300, Fabiano Rosas wrote:
> It makes a bit more sense to have the zero page handling of xbzrle
> right where we save the zero page.
> 
> This also makes save_zero_page() follow the same format as
> save_compress_page() at the top level of
> ram_save_target_page_legacy().
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu