block: remove unused BLOCK_OP_TYPE_DATAPLANE

BLOCK_OP_TYPE_DATAPLANE prevents BlockDriverState from being used by
virtio-blk/virtio-scsi with IOThread. Commit b112a65c52aa ("block:
declare blockjobs and dataplane friends!") eliminated the main reason
for this blocker in 2014.

Nowadays the block layer supports I/O from multiple AioContexts, so
there is even less reason to block IOThread users. Any legitimate
reasons related to interference would probably also apply to
non-IOThread users.

The only remaining users are bdrv_op_unblock(BLOCK_OP_TYPE_DATAPLANE)
calls after bdrv_op_block_all(). If we remove BLOCK_OP_TYPE_DATAPLANE
their behavior doesn't change.

Existing bdrv_op_block_all() callers that don't explicitly unblock
BLOCK_OP_TYPE_DATAPLANE seem to do so simply because no one bothered to
rather than because it is necessary to keep BLOCK_OP_TYPE_DATAPLANE
blocked.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20250203182529.269066-1-stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 0 insertions, 3 deletions

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 23516995dc..7d094e1881 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -1065,9 +1065,6 @@ static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
     int ret;
 
     if (s->ctx && !s->dataplane_fenced) {
-        if (blk_op_is_blocked(sd->conf.blk, BLOCK_OP_TYPE_DATAPLANE, errp)) {
-            return;
-        }
         ret = blk_set_aio_context(sd->conf.blk, s->ctx, errp);
         if (ret < 0) {
             return;