[PATCH v2 05/15] writeback: modify bdi_writeback search logic to search across all wb ctxs

[Kundan Kumar <kundan.kumar@samsung.com>]

Since we have multiple cgwb per bdi, embedded in writeback_ctx now, we
iterate over all of them to find the associated writeback.

Signed-off-by: Kundan Kumar <kundan.kumar@samsung.com>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
---
 fs/fs-writeback.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index e065cd606b80..60c7c912c7f3 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1090,7 +1090,8 @@ int cgroup_writeback_by_id(u64 bdi_id, int memcg_id,
 {
 	struct backing_dev_info *bdi;
 	struct cgroup_subsys_state *memcg_css;
-	struct bdi_writeback *wb;
+	struct bdi_writeback *wb = NULL;
+	struct bdi_writeback_ctx *bdi_wb_ctx;
 	struct wb_writeback_work *work;
 	unsigned long dirty;
 	int ret;
@@ -1114,7 +1115,11 @@ int cgroup_writeback_by_id(u64 bdi_id, int memcg_id,
 	 * And find the associated wb.  If the wb isn't there already
 	 * there's nothing to flush, don't create one.
 	 */
-	wb = wb_get_lookup(bdi->wb_ctx[0], memcg_css);
+	for_each_bdi_wb_ctx(bdi, bdi_wb_ctx) {
+		wb = wb_get_lookup(bdi_wb_ctx, memcg_css);
+		if (wb)
+			break;
+	}
 	if (!wb) {
 		ret = -ENOENT;
 		goto out_css_put;
-- 
2.25.1