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-rw-r--r--block/blk-mq.c103
1 files changed, 54 insertions, 49 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 9690f4f8de7e..af4dc8227954 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1792,78 +1792,83 @@ static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
return ret;
}
-static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
+static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
struct request *rq,
blk_qc_t *cookie,
- bool bypass_insert, bool last)
+ bool bypass, bool last)
{
struct request_queue *q = rq->q;
bool run_queue = true;
+ blk_status_t ret = BLK_STS_RESOURCE;
+ int srcu_idx;
+ bool force = false;
+ hctx_lock(hctx, &srcu_idx);
/*
- * RCU or SRCU read lock is needed before checking quiesced flag.
+ * hctx_lock is needed before checking quiesced flag.
*
- * When queue is stopped or quiesced, ignore 'bypass_insert' from
- * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
- * and avoid driver to try to dispatch again.
+ * When queue is stopped or quiesced, ignore 'bypass', insert
+ * and return BLK_STS_OK to caller, and avoid driver to try to
+ * dispatch again.
*/
- if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
+ if (unlikely(blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q))) {
run_queue = false;
- bypass_insert = false;
- goto insert;
+ bypass = false;
+ goto out_unlock;
}
- if (q->elevator && !bypass_insert)
- goto insert;
+ if (unlikely(q->elevator && !bypass))
+ goto out_unlock;
if (!blk_mq_get_dispatch_budget(hctx))
- goto insert;
+ goto out_unlock;
if (!blk_mq_get_driver_tag(rq)) {
blk_mq_put_dispatch_budget(hctx);
- goto insert;
+ goto out_unlock;
}
- return __blk_mq_issue_directly(hctx, rq, cookie, last);
-insert:
- if (bypass_insert)
- return BLK_STS_RESOURCE;
-
- blk_mq_request_bypass_insert(rq, run_queue);
- return BLK_STS_OK;
-}
-
-static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
- struct request *rq, blk_qc_t *cookie)
-{
- blk_status_t ret;
- int srcu_idx;
-
- might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
-
- hctx_lock(hctx, &srcu_idx);
-
- ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false, true);
- if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
- blk_mq_request_bypass_insert(rq, true);
- else if (ret != BLK_STS_OK)
- blk_mq_end_request(rq, ret);
-
+ /*
+ * Always add a request that has been through
+ *.queue_rq() to the hardware dispatch list.
+ */
+ force = true;
+ ret = __blk_mq_issue_directly(hctx, rq, cookie, last);
+out_unlock:
hctx_unlock(hctx, srcu_idx);
+ switch (ret) {
+ case BLK_STS_OK:
+ break;
+ case BLK_STS_DEV_RESOURCE:
+ case BLK_STS_RESOURCE:
+ if (force) {
+ blk_mq_request_bypass_insert(rq, run_queue);
+ /*
+ * We have to return BLK_STS_OK for the DM
+ * to avoid livelock. Otherwise, we return
+ * the real result to indicate whether the
+ * request is direct-issued successfully.
+ */
+ ret = bypass ? BLK_STS_OK : ret;
+ } else if (!bypass) {
+ blk_mq_sched_insert_request(rq, false,
+ run_queue, false);
+ }
+ break;
+ default:
+ if (!bypass)
+ blk_mq_end_request(rq, ret);
+ break;
+ }
+
+ return ret;
}
blk_status_t blk_mq_request_issue_directly(struct request *rq, bool last)
{
- blk_status_t ret;
- int srcu_idx;
- blk_qc_t unused_cookie;
- struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
+ blk_qc_t unused;
- hctx_lock(hctx, &srcu_idx);
- ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true, last);
- hctx_unlock(hctx, srcu_idx);
-
- return ret;
+ return blk_mq_try_issue_directly(rq->mq_hctx, rq, &unused, true, last);
}
void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
@@ -2004,13 +2009,13 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
if (same_queue_rq) {
data.hctx = same_queue_rq->mq_hctx;
blk_mq_try_issue_directly(data.hctx, same_queue_rq,
- &cookie);
+ &cookie, false, true);
}
} else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator &&
!data.hctx->dispatch_busy)) {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
- blk_mq_try_issue_directly(data.hctx, rq, &cookie);
+ blk_mq_try_issue_directly(data.hctx, rq, &cookie, false, true);
} else {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);