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 <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h
index aa18c4bd..9e9eafa 100644
--- a/include/linux/backing-dev-defs.h
+++ b/include/linux/backing-dev-defs.h
@@ -16,12 +16,15 @@
* Bits in bdi_writeback.state
*/
enum wb_state {
- WB_async_congested, /* The async (write) queue is getting full */
- WB_sync_congested, /* The sync queue is getting full */
WB_registered, /* bdi_register() was done */
WB_writeback_running, /* Writeback is in progress */
};
+enum wb_congested_state {
+ WB_async_congested, /* The async (write) queue is getting full */
+ WB_sync_congested, /* The sync queue is getting full */
+};
+
typedef int (congested_fn)(void *, int);
enum wb_stat_item {
@@ -34,6 +37,10 @@
#define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
+struct bdi_writeback_congested {
+ unsigned long state; /* WB_[a]sync_congested flags */
+};
+
struct bdi_writeback {
struct backing_dev_info *bdi; /* our parent bdi */
@@ -48,6 +55,8 @@
struct percpu_counter stat[NR_WB_STAT_ITEMS];
+ struct bdi_writeback_congested *congested;
+
unsigned long bw_time_stamp; /* last time write bw is updated */
unsigned long dirtied_stamp;
unsigned long written_stamp; /* pages written at bw_time_stamp */
@@ -84,6 +93,7 @@
unsigned int max_ratio, max_prop_frac;
struct bdi_writeback wb; /* default writeback info for this bdi */
+ struct bdi_writeback_congested wb_congested;
struct device *dev;
