[PATCH 12/13] blk: make request able to carry blkcg_gq

[Wang Jianchao]

From: Wang Jianchao <wangjianchao@xxxxxxxxxxxx>

After blk_update_request, the bios can be gone. We cannot track
the req in cgroup fashion in following IO completion path. This
patch add blkcg_gq into request, get it when install bio, put it
before request is released.

Signed-off-by: Wang Jianchao <wangjianchao@xxxxxxxxxxxx>
---
 block/Kconfig          |  3 +++
 block/blk-core.c       |  6 +++++-
 block/blk-merge.c      |  9 +++++++++
 block/blk-mq.c         | 14 ++++++++++++++
 include/linux/blk-mq.h |  4 +++-
 5 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/block/Kconfig b/block/Kconfig
index b3a2c656a64b..ea612cb5c8ee 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -32,6 +32,9 @@ config BLK_BIO_IOCOST
 config BLK_RQ_ALLOC_TIME
 	bool
 
+config BLK_RQ_BLKCG_GQ
+	bool
+
 config BLK_CGROUP_RWSTAT
 	bool
 
diff --git a/block/blk-core.c b/block/blk-core.c
index 2847ab514c1f..083160895125 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1462,7 +1462,11 @@ int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
 	}
 	rq->nr_phys_segments = rq_src->nr_phys_segments;
 	rq->ioprio = rq_src->ioprio;
-
+#ifdef CONFIG_BLK_RQ_BLKCG_GQ
+	if (rq_src->blkg)
+		blkg_get(rq_src->blkg);
+	rq->blkg = rq_src->blkg;
+#endif
 	if (rq->bio && blk_crypto_rq_bio_prep(rq, rq->bio, gfp_mask) < 0)
 		goto free_and_out;
 
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 893c1a60b701..cf5d0e5ce04f 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -793,6 +793,10 @@ static struct request *attempt_merge(struct request_queue *q,
 	if (req->ioprio != next->ioprio)
 		return NULL;
 
+#ifdef CONFIG_BLK_RQ_BLKCG_GQ
+	if (req->blkg != next->blkg)
+		return NULL;
+#endif
 	/*
 	 * If we are allowed to merge, then append bio list
 	 * from next to rq and release next. merge_requests_fn
@@ -930,6 +934,11 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
 	if (rq->ioprio != bio_prio(bio))
 		return false;
 
+#ifdef CONFIG_BLK_RQ_BLKCG_GQ
+	if (rq->blkg != bio->bi_blkg)
+		return false;
+#endif
+
 	return true;
 }
 
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 8874a63ae952..131845bca5de 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -28,6 +28,7 @@
 #include <linux/crash_dump.h>
 #include <linux/prefetch.h>
 #include <linux/blk-crypto.h>
+#include <linux/blk-cgroup.h>
 
 #include <trace/events/block.h>
 
@@ -369,6 +370,9 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
 	rq->nr_phys_segments = 0;
 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 	rq->nr_integrity_segments = 0;
+#endif
+#ifdef CONFIG_BLK_RQ_BLKCG_GQ
+	rq->blkg = NULL;
 #endif
 	rq->end_io = NULL;
 	rq->end_io_data = NULL;
@@ -600,6 +604,10 @@ static void __blk_mq_free_request(struct request *rq)
 	struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
 	const int sched_tag = rq->internal_tag;
 
+#ifdef CONFIG_BLK_RQ_BLKCG_GQ
+	if (rq->blkg)
+		blkg_put(rq->blkg);
+#endif
 	blk_crypto_free_request(rq);
 	blk_pm_mark_last_busy(rq);
 	rq->mq_hctx = NULL;
@@ -2305,6 +2313,12 @@ static void blk_mq_bio_to_request(struct request *rq, struct bio *bio,
 	rq->__sector = bio->bi_iter.bi_sector;
 	rq->write_hint = bio->bi_write_hint;
 	blk_rq_bio_prep(rq, bio, nr_segs);
+#ifdef CONFIG_BLK_RQ_BLKCG_GQ
+	if (bio->bi_blkg) {
+		blkg_get(bio->bi_blkg);
+		rq->blkg = bio->bi_blkg;
+	}
+#endif
 
 	/* This can't fail, since GFP_NOIO includes __GFP_DIRECT_RECLAIM. */
 	err = blk_crypto_rq_bio_prep(rq, bio, GFP_NOIO);
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 2949d9ac7484..f9cc6f6b8d63 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -110,7 +110,9 @@ struct request {
 	u64 start_time_ns;
 	/* Time that I/O was submitted to the device. */
 	u64 io_start_time_ns;
-
+#ifdef CONFIG_BLK_RQ_BLKCG_GQ
+	struct blkcg_gq *blkg;
+#endif
 #ifdef CONFIG_BLK_WBT
 	unsigned short wbt_flags;
 #endif
-- 
2.17.1