tree a99a691af5b57da0f323f9e50ecf68be0d97ff01
parent ac7b19a34f332fdf8b13aac8708b14188fd1fbd2
author Tejun Heo <tj@kernel.org> 1432329238 -0400
committer Jens Axboe <axboe@fb.com> 1433255616 -0600

writeback: implement bdi_wait_for_completion()

If the completion of a wb_writeback_work can be waited upon by setting
its ->done to a struct completion and waiting on it; however, for
cgroup writeback support, it's necessary to issue multiple work items
to multiple bdi_writebacks and wait for the completion of all.

This patch implements wb_completion which can wait for multiple work
items and replaces the struct completion with it.  It can be defined
using DEFINE_WB_COMPLETION_ONSTACK(), used for multiple work items and
waited for by wb_wait_for_completion().

Nobody currently issues multiple work items and this patch doesn't
introduce any behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>