[Qemu-block] [PATCH v2] migration/dirty-bitmaps: change bitmap enumeration method

[John Snow]

Shift from looking at every root BDS to *every* BDS. This will migrate
bitmaps that are attached to blockdev created nodes instead of just ones
attached to emulated storage devices.

Note that this will not migrate anonymous or internal-use bitmaps, as
those are defined as having no name.

This will also fix the Coverity issues Peter Maydell has been asking
about for the past several releases, as well as fixing a real bug.

Reported-by: Peter Maydell <address@hidden>
Reported-by: Coverity 😅
Reported-by: aihua liang <address@hidden>
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1652490
Fixes: Coverity CID 1390625
CC: Stefan Hajnoczi <address@hidden>
Signed-off-by: John Snow <address@hidden>
---
 migration/block-dirty-bitmap.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index d1bb863cb6..4a896a09eb 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -273,7 +273,6 @@ static int init_dirty_bitmap_migration(void)
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;
     DirtyBitmapMigBitmapState *dbms;
-    BdrvNextIterator it;
     Error *local_err = NULL;
 
     dirty_bitmap_mig_state.bulk_completed = false;
@@ -281,13 +280,8 @@ static int init_dirty_bitmap_migration(void)
     dirty_bitmap_mig_state.prev_bitmap = NULL;
     dirty_bitmap_mig_state.no_bitmaps = false;
 
-    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
-        const char *drive_name = bdrv_get_device_or_node_name(bs);
-
-        /* skip automatically inserted nodes */
-        while (bs && bs->drv && bs->implicit) {
-            bs = backing_bs(bs);
-        }
+    for (bs = bdrv_next_all_states(NULL); bs; bs = bdrv_next_all_states(bs)) {
+        const char *name = bdrv_get_device_or_node_name(bs);
 
         for (bitmap = bdrv_dirty_bitmap_next(bs, NULL); bitmap;
              bitmap = bdrv_dirty_bitmap_next(bs, bitmap))
@@ -296,7 +290,7 @@ static int init_dirty_bitmap_migration(void)
                 continue;
             }
 
-            if (drive_name == NULL) {
+            if (!name || strcmp(name, "") == 0) {
                 error_report("Found bitmap '%s' in unnamed node %p. It can't "
                              "be migrated", bdrv_dirty_bitmap_name(bitmap), 
bs);
                 goto fail;
@@ -313,7 +307,7 @@ static int init_dirty_bitmap_migration(void)
 
             dbms = g_new0(DirtyBitmapMigBitmapState, 1);
             dbms->bs = bs;
-            dbms->node_name = drive_name;
+            dbms->node_name = name;
             dbms->bitmap = bitmap;
             dbms->total_sectors = bdrv_nb_sectors(bs);
             dbms->sectors_per_chunk = CHUNK_SIZE * 8 *
-- 
2.20.1