bdi: separate out congested state into a separate struct
Currently, a wb's (bdi_writeback) congestion state is carried in its
->state field; however, cgroup writeback support will require multiple
wb's sharing the same congestion state. This patch separates out
congestion state into its own struct - struct bdi_writeback_congested.
A new field wb field, wb_congested, points to its associated congested
struct. The default wb, bdi->wb, always points to bdi->wb_congested.
While this patch adds a layer of indirection, it doesn't introduce any
behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 7857820..bfdaa18 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -167,7 +167,7 @@
{
if (bdi->congested_fn)
return bdi->congested_fn(bdi->congested_data, bdi_bits);
- return (bdi->wb.state & bdi_bits);
+ return (bdi->wb.congested->state & bdi_bits);
}
static inline int bdi_read_congested(struct backing_dev_info *bdi)