[RFC PATCHv2] block: set bdi congested when no tag available

[zhaoyang.huang]

From: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>

In previous version, block layer will set bdi to be congested when
get_request fail, which may throttle direct_reclaim. Move them back
under current blk-mq design.

Signed-off-by: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
---
v2: simplify the code
---
---
 block/blk-mq-tag.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 995336a..0cbc445 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -11,6 +11,7 @@
 
 #include <linux/blk-mq.h>
 #include <linux/delay.h>
+#include <linux/backing-dev.h>
 #include "blk.h"
 #include "blk-mq.h"
 #include "blk-mq-sched.h"
@@ -126,6 +127,8 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
 	if (tag != BLK_MQ_NO_TAG)
 		goto found_tag;
 
+	set_bdi_congested(data->q->disk->bdi,BLK_RW_SYNC);
+	set_bdi_congested(data->q->disk->bdi,BLK_RW_ASYNC);
 	if (data->flags & BLK_MQ_REQ_NOWAIT)
 		return BLK_MQ_NO_TAG;
 
@@ -190,6 +193,8 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
 		blk_mq_put_tag(tags, data->ctx, tag + tag_offset);
 		return BLK_MQ_NO_TAG;
 	}
+	clear_bdi_congested(data->q->disk->bdi,BLK_RW_SYNC);
+	clear_bdi_congested(data->q->disk->bdi,BLK_RW_ASYNC);
 	return tag + tag_offset;
 }
 
-- 
1.9.1