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authorMing Lei <ming.lei@redhat.com>2018-01-18 12:06:59 +0800
committerJens Axboe <axboe@kernel.dk>2018-01-17 21:38:52 -0700
commit23d4ee19e789ae3dce3e04bd24e3d1537965475f (patch)
treece2feb7137e252bc89dfcd3c00f2f99ea5e0f15f /block
parentde99a346884f019387230bc549de74456daca248 (diff)
downloadlinux-23d4ee19e789ae3dce3e04bd24e3d1537965475f.tar.bz2
blk-mq: don't dispatch request in blk_mq_request_direct_issue if queue is busy
If we run into blk_mq_request_direct_issue(), when queue is busy, we don't want to dispatch this request into hctx->dispatch_list, and what we need to do is to return the queue busy info to caller, so that caller can deal with it well. Fixes: 396eaf21ee ("blk-mq: improve DM's blk-mq IO merging via blk_insert_cloned_request feedback") Reported-by: Laurence Oberman <loberman@redhat.com> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-mq.c22
1 files changed, 10 insertions, 12 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index c418858a60ef..74a4f237ba91 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1773,15 +1773,6 @@ static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
return ret;
}
-static void __blk_mq_fallback_to_insert(struct request *rq,
- bool run_queue, bool bypass_insert)
-{
- if (!bypass_insert)
- blk_mq_sched_insert_request(rq, false, run_queue, false);
- else
- blk_mq_request_bypass_insert(rq, run_queue);
-}
-
static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
struct request *rq,
blk_qc_t *cookie,
@@ -1790,9 +1781,16 @@ static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
struct request_queue *q = rq->q;
bool run_queue = true;
- /* RCU or SRCU read lock is needed before checking quiesced flag */
+ /*
+ * RCU or SRCU read lock is needed before checking quiesced flag.
+ *
+ * When queue is stopped or quiesced, ignore 'bypass_insert' from
+ * blk_mq_request_direct_issue(), 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)) {
run_queue = false;
+ bypass_insert = false;
goto insert;
}
@@ -1809,10 +1807,10 @@ static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
return __blk_mq_issue_directly(hctx, rq, cookie);
insert:
- __blk_mq_fallback_to_insert(rq, run_queue, bypass_insert);
if (bypass_insert)
return BLK_STS_RESOURCE;
+ blk_mq_sched_insert_request(rq, false, run_queue, false);
return BLK_STS_OK;
}
@@ -1828,7 +1826,7 @@ static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false);
if (ret == BLK_STS_RESOURCE)
- __blk_mq_fallback_to_insert(rq, true, false);
+ blk_mq_sched_insert_request(rq, false, true, false);
else if (ret != BLK_STS_OK)
blk_mq_end_request(rq, ret);