On Thu, Aug 17, 2023 at 02:50:08PM +0200, Kevin Wolf wrote: > Instead of taking the writer lock internally, require callers to already > hold it when calling bdrv_replace_child_tran(). These callers will > typically already hold the graph lock once the locking work is > completed, which means that they can't call functions that take it > internally. > > While a graph lock is held, polling is not allowed. Therefore draining > the necessary nodes can no longer be done in bdrv_remove_child() and > bdrv_replace_node_noperm(), but the callers must already make sure that > they are drained. > > Note that the transaction callbacks still take the lock internally, so > tran_finalize() must be called without the lock held. This is because > bdrv_append() also calls bdrv_attach_child_noperm(), which currently > requires to be called unlocked. Once it changes, the transaction > callbacks can be changed, too. > > Signed-off-by: Kevin Wolf <kw...@redhat.com> > --- > block.c | 78 ++++++++++++++++++++++++++++++++++++--------------------- > 1 file changed, 50 insertions(+), 28 deletions(-)
Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
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