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-rw-r--r--block/blk-mq.c82
1 files changed, 59 insertions, 23 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index f13d0de..902c2eb 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1224,6 +1224,38 @@ static struct request *blk_mq_map_request(struct request_queue *q,
return rq;
}
+static int blk_mq_direct_issue_request(struct request *rq)
+{
+ int ret;
+ struct request_queue *q = rq->q;
+ struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q,
+ rq->mq_ctx->cpu);
+ struct blk_mq_queue_data bd = {
+ .rq = rq,
+ .list = NULL,
+ .last = 1
+ };
+
+ /*
+ * For OK queue, we are done. For error, kill it. Any other
+ * error (busy), just add it to our list as we previously
+ * would have done
+ */
+ ret = q->mq_ops->queue_rq(hctx, &bd);
+ if (ret == BLK_MQ_RQ_QUEUE_OK)
+ return 0;
+ else {
+ __blk_mq_requeue_request(rq);
+
+ if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
+ rq->errors = -EIO;
+ blk_mq_end_request(rq, rq->errors);
+ return 0;
+ }
+ return -1;
+ }
+}
+
/*
* Multiple hardware queue variant. This will not use per-process plugs,
* but will attempt to bypass the hctx queueing if we can go straight to
@@ -1235,6 +1267,8 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
struct blk_map_ctx data;
struct request *rq;
+ unsigned int request_count = 0;
+ struct blk_plug *plug;
blk_queue_bounce(q, &bio);
@@ -1243,6 +1277,10 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
return;
}
+ if (!is_flush_fua && !blk_queue_nomerges(q) &&
+ blk_attempt_plug_merge(q, bio, &request_count))
+ return;
+
rq = blk_mq_map_request(q, bio, &data);
if (unlikely(!rq))
return;
@@ -1253,40 +1291,39 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
goto run_queue;
}
+ plug = current->plug;
/*
* If the driver supports defer issued based on 'last', then
* queue it up like normal since we can potentially save some
* CPU this way.
*/
- if (is_sync && !(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
- struct blk_mq_queue_data bd = {
- .rq = rq,
- .list = NULL,
- .last = 1
- };
- int ret;
+ if (((plug && !blk_queue_nomerges(q)) || is_sync) &&
+ !(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
+ struct request *old_rq = NULL;
blk_mq_bio_to_request(rq, bio);
/*
- * For OK queue, we are done. For error, kill it. Any other
- * error (busy), just add it to our list as we previously
- * would have done
+ * we do limited pluging. If bio can be merged, do merge.
+ * Otherwise the existing request in the plug list will be
+ * issued. So the plug list will have one request at most
*/
- ret = q->mq_ops->queue_rq(data.hctx, &bd);
- if (ret == BLK_MQ_RQ_QUEUE_OK)
- goto done;
- else {
- __blk_mq_requeue_request(rq);
-
- if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
- rq->errors = -EIO;
- blk_mq_end_request(rq, rq->errors);
- goto done;
+ if (plug) {
+ if (!list_empty(&plug->mq_list)) {
+ old_rq = list_first_entry(&plug->mq_list,
+ struct request, queuelist);
+ list_del_init(&old_rq->queuelist);
}
- blk_mq_insert_request(rq, false, true, true);
+ list_add_tail(&rq->queuelist, &plug->mq_list);
+ } else /* is_sync */
+ old_rq = rq;
+ blk_mq_put_ctx(data.ctx);
+ if (!old_rq)
return;
- }
+ if (!blk_mq_direct_issue_request(old_rq))
+ return;
+ blk_mq_insert_request(old_rq, false, true, true);
+ return;
}
if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
@@ -1299,7 +1336,6 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
run_queue:
blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
}
-done:
blk_mq_put_ctx(data.ctx);
}
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