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Subject: Re: [PATCH v2 1/2] io_uring: Merge io_submit_sqes and io_ring_submit
To:     Bob Liu <bob.liu@oracle.com>, Jens Axboe <axboe@kernel.dk>,
        io-uring@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <cover.1572988512.git.asml.silence@gmail.com>
 <09fcce1a50f4d1a399b903e3669ba98ede408d9c.1572988512.git.asml.silence@gmail.com>
 <4654948b-caac-3dc8-904c-ceb0c245d7c3@oracle.com>
From:   Pavel Begunkov <asml.silence@gmail.com>
Message-ID: <62cc24d9-0ace-3a9e-f8ed-9c2b8b920ba0@gmail.com>
Date:   Wed, 6 Nov 2019 12:07:53 +0300
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On 11/6/2019 11:57 AM, Bob Liu wrote:
> On 11/6/19 5:22 AM, Pavel Begunkov wrote:
>> io_submit_sqes() and io_ring_submit() are doing the same stuff with
>> a little difference. Deduplicate them.
>>
>> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
>> ---
>>  fs/io_uring.c | 88 +++++++++++----------------------------------------
>>  1 file changed, 18 insertions(+), 70 deletions(-)
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index 7813bc7d5b61..ebe2a4edd644 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -2681,7 +2681,8 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
>>  }
>>  
>>  static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
>> -			  struct mm_struct **mm)
>> +			  struct file *ring_file, int ring_fd,
>> +			  struct mm_struct **mm, bool async)
>>  {
>>  	struct io_submit_state state, *statep = NULL;
>>  	struct io_kiocb *link = NULL;
>> @@ -2732,10 +2733,12 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
>>  		}
>>  
>>  out:
>> +		s.ring_file = ring_file;
>> +		s.ring_fd = ring_fd;
>>  		s.has_user = *mm != NULL;
>> -		s.in_async = true;
>> -		s.needs_fixed_file = true;
>> -		trace_io_uring_submit_sqe(ctx, s.sqe->user_data, true, true);
>> +		s.in_async = async;
>> +		s.needs_fixed_file = async;
>> +		trace_io_uring_submit_sqe(ctx, s.sqe->user_data, true, async);
>>  		io_submit_sqe(ctx, &s, statep, &link);
>>  		submitted++;
>>  	}
>> @@ -2745,6 +2748,9 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
>>  	if (statep)
>>  		io_submit_state_end(&state);
>>  
>> +	 /* Commit SQ ring head once we've consumed and submitted all SQEs */
>> +	io_commit_sqring(ctx);
>> +
> 
> Then don't need io_commit_sqring() in io_sq_thread any more?
>
Right, thanks! I'll resend with the change.


> Anyway, looks good to me.
> Reviewed-by: Bob Liu <bob.liu@oracle.com>
> 
>>  	return submitted;
>>  }
>>  
>> @@ -2849,7 +2855,8 @@ static int io_sq_thread(void *data)
>>  		}
>>  
>>  		to_submit = min(to_submit, ctx->sq_entries);
>> -		inflight += io_submit_sqes(ctx, to_submit, &cur_mm);
>> +		inflight += io_submit_sqes(ctx, to_submit, NULL, -1, &cur_mm,
>> +					   true);
>>  
>>  		/* Commit SQ ring head once we've consumed all SQEs */
>>  		io_commit_sqring(ctx);
>> @@ -2866,69 +2873,6 @@ static int io_sq_thread(void *data)
>>  	return 0;
>>  }
>>  
>> -static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit,
>> -			  struct file *ring_file, int ring_fd)
>> -{
>> -	struct io_submit_state state, *statep = NULL;
>> -	struct io_kiocb *link = NULL;
>> -	struct io_kiocb *shadow_req = NULL;
>> -	bool prev_was_link = false;
>> -	int i, submit = 0;
>> -
>> -	if (to_submit > IO_PLUG_THRESHOLD) {
>> -		io_submit_state_start(&state, ctx, to_submit);
>> -		statep = &state;
>> -	}
>> -
>> -	for (i = 0; i < to_submit; i++) {
>> -		struct sqe_submit s;
>> -
>> -		if (!io_get_sqring(ctx, &s))
>> -			break;
>> -
>> -		/*
>> -		 * If previous wasn't linked and we have a linked command,
>> -		 * that's the end of the chain. Submit the previous link.
>> -		 */
>> -		if (!prev_was_link && link) {
>> -			io_queue_link_head(ctx, link, &link->submit, shadow_req);
>> -			link = NULL;
>> -			shadow_req = NULL;
>> -		}
>> -		prev_was_link = (s.sqe->flags & IOSQE_IO_LINK) != 0;
>> -
>> -		if (link && (s.sqe->flags & IOSQE_IO_DRAIN)) {
>> -			if (!shadow_req) {
>> -				shadow_req = io_get_req(ctx, NULL);
>> -				if (unlikely(!shadow_req))
>> -					goto out;
>> -				shadow_req->flags |= (REQ_F_IO_DRAIN | REQ_F_SHADOW_DRAIN);
>> -				refcount_dec(&shadow_req->refs);
>> -			}
>> -			shadow_req->sequence = s.sequence;
>> -		}
>> -
>> -out:
>> -		s.ring_file = ring_file;
>> -		s.has_user = true;
>> -		s.in_async = false;
>> -		s.needs_fixed_file = false;
>> -		s.ring_fd = ring_fd;
>> -		submit++;
>> -		trace_io_uring_submit_sqe(ctx, s.sqe->user_data, true, false);
>> -		io_submit_sqe(ctx, &s, statep, &link);
>> -	}
>> -
>> -	if (link)
>> -		io_queue_link_head(ctx, link, &link->submit, shadow_req);
>> -	if (statep)
>> -		io_submit_state_end(statep);
>> -
>> -	io_commit_sqring(ctx);
>> -
>> -	return submit;
>> -}
>> -
>>  struct io_wait_queue {
>>  	struct wait_queue_entry wq;
>>  	struct io_ring_ctx *ctx;
>> @@ -4049,10 +3993,14 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
>>  			wake_up(&ctx->sqo_wait);
>>  		submitted = to_submit;
>>  	} else if (to_submit) {
>> -		to_submit = min(to_submit, ctx->sq_entries);
>> +		struct mm_struct *cur_mm;
>>  
>> +		to_submit = min(to_submit, ctx->sq_entries);
>>  		mutex_lock(&ctx->uring_lock);
>> -		submitted = io_ring_submit(ctx, to_submit, f.file, fd);
>> +		/* already have mm, so io_submit_sqes() won't try to grab it */
>> +		cur_mm = ctx->sqo_mm;
>> +		submitted = io_submit_sqes(ctx, to_submit, f.file, fd,
>> +					   &cur_mm, false);
>>  		mutex_unlock(&ctx->uring_lock);
>>  	}
>>  	if (flags & IORING_ENTER_GETEVENTS) {
>>
>