If the driver does not support .bdrv_co_flush() so bdrv_co_flush()
itself has to flush the children of the given node, it should not flush
just bs->file->bs, but in fact all children that might have been written
to (judging from the permissions taken on them).
This is a bug fix for qcow2 images with an external data file, as they
so far did not flush that data_file node.
In any case, the BLKDBG_EVENT() should be emitted on the primary child,
because that is where a blkdebug node would be if there is any.
Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
block/io.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
@@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
/* Now flush the underlying protocol. It will also have BDRV_O_NO_FLUSH
* in the case of cache=unsafe, so there are no useless flushes.
*/
-flush_parent:
- ret = bs->file ? bdrv_co_flush(bs->file->bs) : 0;
+flush_children:
+ ret = 0;
+ QLIST_FOREACH(child, &bs->children, next) {
+ if (child->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) {
+ int this_child_ret = bdrv_co_flush(child->bs);
+ if (!ret) {
+ ret = this_child_ret;
+ }
+ }
+ }
+
out:
/* Notify any pending flushes that we have completed */
if (ret == 0) {