于 2016/4/24 5:37, Jens Axboe 写道:
> On 04/23/2016 02:21 AM, xiakaixu wrote:
>>> diff --git a/block/blk-core.c b/block/blk-core.c
>>> index 40b57bf4852c..d941f69dfb4b 100644
>>> --- a/block/blk-core.c
>>> +++ b/block/blk-core.c
>>> @@ -39,6 +39,7 @@
>>>
>>> #include "blk.h"
>>> #include "blk-mq.h"
>>> +#include "blk-wb.h"
>>>
>>> EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
>>> EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
>>> @@ -880,6 +881,7 @@ blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
>>>
>>> fail:
>>> blk_free_flush_queue(q->fq);
>>> + blk_wb_exit(q);
>>> return NULL;
>>> }
>>> EXPORT_SYMBOL(blk_init_allocated_queue);
>>> @@ -1395,6 +1397,7 @@ void blk_requeue_request(struct request_queue *q, struct request *rq)
>>> blk_delete_timer(rq);
>>> blk_clear_rq_complete(rq);
>>> trace_block_rq_requeue(q, rq);
>>> + blk_wb_requeue(q->rq_wb, rq);
>>>
>>> if (rq->cmd_flags & REQ_QUEUED)
>>> blk_queue_end_tag(q, rq);
>>> @@ -1485,6 +1488,8 @@ void __blk_put_request(struct request_queue *q, struct request *req)
>>> /* this is a bio leak */
>>> WARN_ON(req->bio != NULL);
>>>
>>> + blk_wb_done(q->rq_wb, req);
>>> +
>>> /*
>>> * Request may not have originated from ll_rw_blk. if not,
>>> * it didn't come out of our reserved rq pools
>>> @@ -1714,6 +1719,7 @@ static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
>>> int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT;
>>> struct request *req;
>>> unsigned int request_count = 0;
>>> + bool wb_acct;
>>>
>>> /*
>>> * low level driver can indicate that it wants pages above a
>>> @@ -1766,6 +1772,8 @@ static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
>>> }
>>>
>>> get_rq:
>>> + wb_acct = blk_wb_wait(q->rq_wb, bio, q->queue_lock);
>>> +
>>> /*
>>> * This sync check and mask will be re-done in init_request_from_bio(),
>>> * but we need to set it earlier to expose the sync flag to the
>>> @@ -1781,11 +1789,16 @@ get_rq:
>>> */
>>> req = get_request(q, rw_flags, bio, GFP_NOIO);
>>> if (IS_ERR(req)) {
>>> + if (wb_acct)
>>> + __blk_wb_done(q->rq_wb);
>>> bio->bi_error = PTR_ERR(req);
>>> bio_endio(bio);
>>> goto out_unlock;
>>> }
>>>
>>> + if (wb_acct)
>>> + req->cmd_flags |= REQ_BUF_INFLIGHT;
>>> +
>>> /*
>>> * After dropping the lock and possibly sleeping here, our request
>>> * may now be mergeable after it had proven unmergeable (above).
>>> @@ -2515,6 +2528,7 @@ void blk_start_request(struct request *req)
>>> blk_dequeue_request(req);
>>>
>>> req->issue_time = ktime_to_ns(ktime_get());
>>> + blk_wb_issue(req->q->rq_wb, req);
>>>
>>> /*
>>> * We are now handing the request to the hardware, initialize
>>> @@ -2751,6 +2765,7 @@ void blk_finish_request(struct request *req, int error)
>>> blk_unprep_request(req);
>>>
>>> blk_account_io_done(req);
>>> + blk_wb_done(req->q->rq_wb, req);
>>
>> Hi Jens,
>>
>> Seems the function blk_wb_done() will be executed twice even if the end_io
>> callback is set.
>> Maybe the same thing would happen in blk-mq.c.
>
> Yeah, that was a mistake, the current version has it fixed. It was inadvertently added when I discovered that the flush request didn't work properly. Now it just duplicates the call inside the check for if it has an ->end_io() defined, since we don't use the normal path for that.
>
Hi Jens,
I have checked the wb-buf-throttle branch in your block git repo. I am not sure it is the completed version.
Seems only the problem is fixed in blk-mq.c. The function blk_wb_done() still would be executed twice in blk-core.c.
(the functions blk_finish_request() and __blk_put_request())
Maybe we can add a flag to mark whether blk_wb_done() has been done or not.
--
Regards
Kaixu Xia
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