Commits
Konrad Rzeszutek Wilk committed 0faa8cca883
xen/blkback: remove per-queue plugging
commit 7eaceaccab5f40bbfda044629a6298616aeaed50 ("block: remove per-queue plugging")
added two new interfaces to plug and unplug: blk_start_plug
and blk_finish_plug. Lets use those.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>