On 12/6/18 12:25 AM, Jens Axboe wrote:
> On 12/5/18 12:43 AM, Jianchao Wang wrote:
>> We don't allow direct dispatch of anything but regular reads/writes
>> and insert all of non-read-write requests. However, this is not
>> correct for 'bypass_insert == true' case where inserting is ignored
>> and BLK_STS_RESOURCE is returned. The caller will fail forever.
>>
>> Fix it with inserting the non-read-write request to hctx dispatch
>> list to avoid to involve merge and io scheduler when bypass_insert
>> is true.
>>
>> Signed-off-by: Jianchao Wang <[email protected]>
>> ---
>> block/blk-mq.c | 19 +++++++++++++++++--
>> 1 file changed, 17 insertions(+), 2 deletions(-)
>>
>> diff --git a/block/blk-mq.c b/block/blk-mq.c
>> index 9005505..153af90 100644
>> --- a/block/blk-mq.c
>> +++ b/block/blk-mq.c
>> @@ -1822,6 +1822,7 @@ 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;
>> + bool force = false;
>>
>> /*
>> * RCU or SRCU read lock is needed before checking quiesced flag.
>> @@ -1836,9 +1837,19 @@ static blk_status_t
>> __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
>> goto insert;
>> }
>>
>> - if (!blk_rq_can_direct_dispatch(rq) || (q->elevator && !bypass_insert))
>> + if (q->elevator && !bypass_insert)
>> goto insert;
>>
>> + if (!blk_rq_can_direct_dispatch(rq)) {
>> + /*
>> + * For 'bypass_insert == true' case, insert request into hctx
>> + * dispatch list.
>> + */
>> + if (bypass_insert)
>> + force = true;
>> + goto insert;
>> + }
>
> Just do force = bypass_insert, no need for the if.
>
Yes, I will do it.
Thanks
Jianchao
