lkml.org 
[lkml]   [2018]   [Oct]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH V3 2/4] blk-mq: insert request without involving any io scheduler
Date
When try to issue request directly, if the queue is stopped or
quiesced, 'bypass_insert' will be ignored and return BLK_STS_OK to
caller to avoid it dispatch request again. Then the request will
be inserted with blk_mq_sched_insert_request. This is not correct
for dm-rq case where we should avoid to pass through the underlying
paths' io scheduler.

To fix it, use blk_mq_request_bypass_insert to insert the request
into hctx->dispatch directly.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
---
block/blk-mq.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 0f6328b..e0aa068 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1729,13 +1729,14 @@ static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
}

enum mq_decision {
+ MQ_INSERT_DISPATCH,
MQ_INSERT_QUEUE,
MQ_END_REQUEST,
MQ_DO_NOTHING,
};

static inline enum mq_decision
- blk_mq_make_dicision(blk_status_t ret, bool bypass_insert)
+ blk_mq_make_dicision(blk_status_t ret, bool bypass_insert, bool force)
{
enum mq_decision dec;

@@ -1745,7 +1746,10 @@ static inline enum mq_decision
break;
case BLK_STS_DEV_RESOURCE:
case BLK_STS_RESOURCE:
- dec = bypass_insert ? MQ_DO_NOTHING : MQ_INSERT_QUEUE;
+ if (force)
+ dec = bypass_insert ? MQ_INSERT_DISPATCH : MQ_INSERT_QUEUE;
+ else
+ dec = bypass_insert ? MQ_DO_NOTHING : MQ_INSERT_QUEUE;
break;
default:
dec = bypass_insert ? MQ_DO_NOTHING : MQ_END_REQUEST;
@@ -1761,7 +1765,7 @@ static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
bool bypass_insert)
{
struct request_queue *q = rq->q;
- bool run_queue = true;
+ bool run_queue = true, force = false;
enum mq_decision dec;
blk_status_t ret = BLK_STS_RESOURCE;
int srcu_idx;
@@ -1776,7 +1780,7 @@ static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
*/
if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
run_queue = false;
- bypass_insert = false;
+ force = true;
goto out_unlock;
}

@@ -1795,8 +1799,11 @@ static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
out_unlock:
hctx_unlock(hctx, srcu_idx);

- dec = blk_mq_make_dicision(ret, bypass_insert);
+ dec = blk_mq_make_dicision(ret, bypass_insert, force);
switch(dec) {
+ case MQ_INSERT_DISPATCH:
+ blk_mq_request_bypass_insert(rq, run_queue);
+ break;
case MQ_INSERT_QUEUE:
blk_mq_sched_insert_request(rq, false, run_queue, false);
break;
--
2.7.4
\
 
 \ /
  Last update: 2018-10-29 09:50    [W:0.039 / U:0.284 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site