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-rw-r--r--block/blk-merge.c11
-rw-r--r--include/linux/blk-cgroup.h17
2 files changed, 28 insertions, 0 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 4b022f0c49d2..a62692d13566 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -7,6 +7,7 @@
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/scatterlist.h>
+#include <linux/blk-cgroup.h>
#include <trace/events/block.h>
@@ -571,6 +572,9 @@ static inline unsigned int blk_rq_get_max_segments(struct request *rq)
static inline int ll_new_hw_segment(struct request *req, struct bio *bio,
unsigned int nr_phys_segs)
{
+ if (!blk_cgroup_mergeable(req, bio))
+ goto no_merge;
+
if (blk_integrity_merge_bio(req->q, req, bio) == false)
goto no_merge;
@@ -662,6 +666,9 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
if (total_phys_segments > blk_rq_get_max_segments(req))
return 0;
+ if (!blk_cgroup_mergeable(req, next->bio))
+ return 0;
+
if (blk_integrity_merge_rq(q, req, next) == false)
return 0;
@@ -885,6 +892,10 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
if (rq->rq_disk != bio->bi_disk)
return false;
+ /* don't merge across cgroup boundaries */
+ if (!blk_cgroup_mergeable(rq, bio))
+ return false;
+
/* only merge integrity protected bio into ditto rq */
if (blk_integrity_merge_bio(rq->q, rq, bio) == false)
return false;
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index bed9e43f9426..46139c0f510f 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -22,6 +22,7 @@
#include <linux/atomic.h>
#include <linux/kthread.h>
#include <linux/fs.h>
+#include <linux/blkdev.h>
/* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */
#define BLKG_STAT_CPU_BATCH (INT_MAX / 2)
@@ -768,6 +769,21 @@ static inline void blkcg_use_delay(struct blkcg_gq *blkg)
atomic_inc(&blkg->blkcg->css.cgroup->congestion_count);
}
+/**
+ * blk_cgroup_mergeable - Determine whether to allow or disallow merges
+ * @rq: request to merge into
+ * @bio: bio to merge
+ *
+ * @bio and @rq should belong to the same cgroup and their issue_as_root should
+ * match. The latter is necessary as we don't want to throttle e.g. a metadata
+ * update because it happens to be next to a regular IO.
+ */
+static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio)
+{
+ return rq->bio->bi_blkg == bio->bi_blkg &&
+ bio_issue_as_root_blkg(rq->bio) == bio_issue_as_root_blkg(bio);
+}
+
static inline int blkcg_unuse_delay(struct blkcg_gq *blkg)
{
int old = atomic_read(&blkg->use_delay);
@@ -868,6 +884,7 @@ static inline bool blkcg_punt_bio_submit(struct bio *bio) { return false; }
static inline void blkcg_bio_issue_init(struct bio *bio) { }
static inline bool blkcg_bio_issue_check(struct request_queue *q,
struct bio *bio) { return true; }
+static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio) { return true; }
#define blk_queue_for_each_rl(rl, q) \
for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)