[PATCH 03/13] writeback: link bdi_writeback to its corresponding bdi_writeback_ctx

[Kundan Kumar <kundan.kumar@xxxxxxxxxxx>]

Introduce a bdi_writeback_ctx field in bdi_writeback. This helps in
fetching the writeback context from the bdi_writeback.

Signed-off-by: Kundan Kumar <kundan.kumar@xxxxxxxxxxx>
Signed-off-by: Anuj Gupta <anuj20.g@xxxxxxxxxxx>
---
 mm/backing-dev.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index adf87b036827..5479e2d34160 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -513,15 +513,16 @@ static void wb_update_bandwidth_workfn(struct work_struct *work)
  */
 #define INIT_BW		(100 << (20 - PAGE_SHIFT))
 
-static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
-		   gfp_t gfp)
+static int wb_init(struct bdi_writeback *wb,
+		   struct bdi_writeback_ctx *bdi_wb_ctx,
+		   struct backing_dev_info *bdi, gfp_t gfp)
 {
 	int err;
 
 	memset(wb, 0, sizeof(*wb));
 
 	wb->bdi = bdi;
-	wb->bdi_wb_ctx = bdi->wb_ctx_arr[0];
+	wb->bdi_wb_ctx = bdi_wb_ctx;
 	wb->last_old_flush = jiffies;
 	INIT_LIST_HEAD(&wb->b_dirty);
 	INIT_LIST_HEAD(&wb->b_io);
@@ -698,7 +699,7 @@ static int cgwb_create(struct backing_dev_info *bdi,
 		goto out_put;
 	}
 
-	ret = wb_init(wb, bdi, gfp);
+	ret = wb_init(wb, bdi_wb_ctx, bdi, gfp);
 	if (ret)
 		goto err_free;
 
@@ -843,7 +844,7 @@ static int cgwb_bdi_init(struct backing_dev_info *bdi)
 		mutex_init(&bdi->cgwb_release_mutex);
 		init_rwsem(&bdi_wb_ctx->wb_switch_rwsem);
 
-		ret = wb_init(&bdi_wb_ctx->wb, bdi, GFP_KERNEL);
+		ret = wb_init(&bdi_wb_ctx->wb, bdi_wb_ctx, bdi, GFP_KERNEL);
 		if (!ret) {
 			bdi_wb_ctx->wb.memcg_css = &root_mem_cgroup->css;
 			bdi_wb_ctx->wb.blkcg_css = blkcg_root_css;
@@ -1000,7 +1001,7 @@ static int cgwb_bdi_init(struct backing_dev_info *bdi)
 	for_each_bdi_wb_ctx(bdi, bdi_wb_ctx) {
 		int ret;
 
-		ret = wb_init(&bdi_wb_ctx->wb, bdi, GFP_KERNEL);
+		ret = wb_init(&bdi_wb_ctx->wb, bdi_wb_ctx, bdi, GFP_KERNEL);
 		if (ret)
 			return ret;
 	}
-- 
2.25.1