Am 12.10.2015 um 13:50 hat Fam Zheng geschrieben: > The semantics is that after bdrv_drained_begin(bs), bs will not get new > external > requests until the matching bdrv_drained_end(bs). > > Signed-off-by: Fam Zheng <f...@redhat.com> > --- > block.c | 2 ++ > block/io.c | 18 ++++++++++++++++++ > include/block/block.h | 19 +++++++++++++++++++ > include/block/block_int.h | 2 ++ > 4 files changed, 41 insertions(+) > > diff --git a/block.c b/block.c > index 1f90b47..9b28a07 100644 > --- a/block.c > +++ b/block.c > @@ -2058,6 +2058,8 @@ static void bdrv_move_feature_fields(BlockDriverState > *bs_dest, > bs_dest->device_list = bs_src->device_list; > bs_dest->blk = bs_src->blk; > > + bs_dest->quiesce_counter = bs_src->quiesce_counter; > + > memcpy(bs_dest->op_blockers, bs_src->op_blockers, > sizeof(bs_dest->op_blockers)); > }
This feels wrong. As I understand it, bdrv_drained_begin/end works on specific nodes and not on trees. Including the field in bdrv_move_feature_fields() means that it moves to the top of the tree (i.e. it stays at in the same C object, which however belongs to a different logical node now). What I could imagine is that you did this so you can use bdrv_draind_end() on the same BDS as you called bdrv_drained_start() on. However, that's not the interface of bdrv_swap(), which really means that the BDSes are swapped. So with this hunk you just end up having a bug that cancels out the weirdness of the bdrv_swap() interface. If you rebase on my bdrv_swap() removal series, things become a bit more obvious. If you don't, you should drop this hunk and change some bdrv_drained_end() calls, e.g. in the next patch, you'd have to call bdrv_drained_begin(state->old_bs), but bdrv_drained_end(state->new_bs). The rest of this patch looks good. Kevin
