block: Avoid bs->blk in bdrv_next()

We need to introduce a separate BdrvNextIterator struct that can keep
more state than just the current BDS in order to avoid using the bs->blk
pointer.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/migration/block.c b/migration/block.c
index 1743317288..a7a76a0fb9 100644
--- a/migration/block.c
+++ b/migration/block.c
@@ -383,6 +383,7 @@ static void init_blk_migration(QEMUFile *f)
     BlockDriverState *bs;
     BlkMigDevState *bmds;
     int64_t sectors;
+    BdrvNextIterator *it = NULL;
 
     block_mig_state.submitted = 0;
     block_mig_state.read_done = 0;
@@ -392,7 +393,8 @@ static void init_blk_migration(QEMUFile *f)
     block_mig_state.bulk_completed = 0;
     block_mig_state.zero_blocks = migrate_zero_blocks();
 
-    for (bs = bdrv_next(NULL); bs; bs = bdrv_next(bs)) {
+
+    while ((it = bdrv_next(it, &bs))) {
         if (bdrv_is_read_only(bs)) {
             continue;
         }