[PATCH v2 3/8] migration: Drop postcopy_chunk_hostpages()

[Peter Xu <peterx@redhat.com>]

This function calls three functions:

  - postcopy_discard_send_init(ms, block->idstr);
  - postcopy_chunk_hostpages_pass(ms, block);
  - postcopy_discard_send_finish(ms);

However only the 2nd function call is meaningful.  It's major role is to make
sure dirty bits are applied in host-page-size granule, so there will be no
partial dirty bits set for a whole host page if huge pages are used.

The 1st/3rd call are for latter when we want to send the disgard ranges.
They're mostly no-op here besides some tracepoints (which are misleading!).

Drop them, then we can directly drop postcopy_chunk_hostpages() as a whole
because we can call postcopy_chunk_hostpages_pass() directly.

There're still some nice comments above postcopy_chunk_hostpages() that explain
what it does.  Copy it over to the caller's site.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/ram.c | 33 +++++++--------------------------
 1 file changed, 7 insertions(+), 26 deletions(-)

diff --git a/migration/ram.c b/migration/ram.c
index 0ed0f51a09..b22c9e7432 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2571,30 +2571,6 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, RAMBlock *block)
     }
 }
 
-/**
- * postcopy_chunk_hostpages: discard any partially sent host page
- *
- * Utility for the outgoing postcopy code.
- *
- * Discard any partially sent host-page size chunks, mark any partially
- * dirty host-page size chunks as all dirty.  In this case the host-page
- * is the host-page for the particular RAMBlock, i.e. it might be a huge page
- *
- * @ms: current migration state
- * @block: block we want to work with
- */
-static void postcopy_chunk_hostpages(MigrationState *ms, RAMBlock *block)
-{
-    postcopy_discard_send_init(ms, block->idstr);
-
-    /*
-     * Ensure that all partially dirty host pages are made fully dirty.
-     */
-    postcopy_chunk_hostpages_pass(ms, block);
-
-    postcopy_discard_send_finish(ms);
-}
-
 /**
  * ram_postcopy_send_discard_bitmap: transmit the discard bitmap
  *
@@ -2626,8 +2602,13 @@ int ram_postcopy_send_discard_bitmap(MigrationState *ms)
     rs->last_page = 0;
 
     RAMBLOCK_FOREACH_NOT_IGNORED(block) {
-        /* Deal with TPS != HPS and huge pages */
-        postcopy_chunk_hostpages(ms, block);
+        /*
+         * Deal with TPS != HPS and huge pages.  It discard any partially sent
+         * host-page size chunks, mark any partially dirty host-page size
+         * chunks as all dirty.  In this case the host-page is the host-page
+         * for the particular RAMBlock, i.e. it might be a huge page.
+         */
+        postcopy_chunk_hostpages_pass(ms, block);
     }
     trace_ram_postcopy_send_discard_bitmap();
 
-- 
2.32.0