2019-09-30 08:30:02

by Pavel Begunkov

[permalink] [raw]
Subject: [PATCH 1/1] blk-mq: reuse code in blk_mq_check_inflight*()

From: Pavel Begunkov <[email protected]>

1. Reuse the same walker callback for both blk_mq_in_flight() and
blk_mq_in_flight_rw().

2. Store inflight counters immediately in struct mq_inflight.
It's type-safer and removes extra indirection.

Signed-off-by: Pavel Begunkov <[email protected]>
---
block/blk-mq.c | 32 ++++++++------------------------
1 file changed, 8 insertions(+), 24 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index c4e5070c2ecd..d97181d9a3ec 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -93,7 +93,7 @@ static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,

struct mq_inflight {
struct hd_struct *part;
- unsigned int *inflight;
+ unsigned int inflight[2];
};

static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
@@ -102,45 +102,29 @@ static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
{
struct mq_inflight *mi = priv;

- /*
- * index[0] counts the specific partition that was asked for.
- */
if (rq->part == mi->part)
- mi->inflight[0]++;
+ mi->inflight[rq_data_dir(rq)]++;

return true;
}

unsigned int blk_mq_in_flight(struct request_queue *q, struct hd_struct *part)
{
- unsigned inflight[2];
- struct mq_inflight mi = { .part = part, .inflight = inflight, };
+ struct mq_inflight mi = { .part = part };

- inflight[0] = inflight[1] = 0;
blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);

- return inflight[0];
-}
-
-static bool blk_mq_check_inflight_rw(struct blk_mq_hw_ctx *hctx,
- struct request *rq, void *priv,
- bool reserved)
-{
- struct mq_inflight *mi = priv;
-
- if (rq->part == mi->part)
- mi->inflight[rq_data_dir(rq)]++;
-
- return true;
+ return mi.inflight[0] + mi.inflight[1];
}

void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
unsigned int inflight[2])
{
- struct mq_inflight mi = { .part = part, .inflight = inflight, };
+ struct mq_inflight mi = { .part = part };

- inflight[0] = inflight[1] = 0;
- blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight_rw, &mi);
+ blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
+ inflight[0] = mi.inflight[0];
+ inflight[1] = mi.inflight[1];
}

void blk_freeze_queue_start(struct request_queue *q)
--
2.23.0


2019-09-30 08:36:44

by Christoph Hellwig

[permalink] [raw]
Subject: Re: [PATCH 1/1] blk-mq: reuse code in blk_mq_check_inflight*()

On Mon, Sep 30, 2019 at 11:27:32AM +0300, Pavel Begunkov (Silence) wrote:
> From: Pavel Begunkov <[email protected]>
>
> 1. Reuse the same walker callback for both blk_mq_in_flight() and
> blk_mq_in_flight_rw().
>
> 2. Store inflight counters immediately in struct mq_inflight.
> It's type-safer and removes extra indirection.

You really want to split this into two patches. Part 2 looks very
sensible to me, but I don't really see how 1 is qn equivalent
transformation right now. Splitting it out and writing a non-trivial
changelog might help understanding it if you think it really is
equivalent as-is.

2019-09-30 09:21:57

by Pavel Begunkov

[permalink] [raw]
Subject: Re: [PATCH 1/1] blk-mq: reuse code in blk_mq_check_inflight*()

On 9/30/2019 11:33 AM, Christoph Hellwig wrote:
> On Mon, Sep 30, 2019 at 11:27:32AM +0300, Pavel Begunkov (Silence) wrote:
>> From: Pavel Begunkov <[email protected]>
>>
>> 1. Reuse the same walker callback for both blk_mq_in_flight() and
>> blk_mq_in_flight_rw().
>>
>> 2. Store inflight counters immediately in struct mq_inflight.
>> It's type-safer and removes extra indirection.
>
> You really want to split this into two patches. Part 2 looks very

Good point, diff is peculiarly aligned indeed. I will resend it.

> sensible to me, but I don't really see how 1 is qn equivalent
> transformation right now. Splitting it out and writing a non-trivial
> changelog might help understanding it if you think it really is
> equivalent as-is.
>

blk_mq_check_inflight() increments only inflight[0].
blk_mq_check_inflight_rw() increments inflight[0] or inflight[1]
depending on a flag, so summing them gives what the first function returns.

--
Yours sincerely,
Pavel Begunkov

2019-09-30 20:44:41

by Pavel Begunkov

[permalink] [raw]
Subject: [PATCH v2 0/2] Simplify blk_mq_in_flight*

From: Pavel Begunkov <[email protected]>

Clean up inflight counting code. Deduplicate it and fortify with types.

v2: splitting the patch in two by Christoph suggestion

Pavel Begunkov (2):
blk-mq: Reuse callback in blk_mq_in_flight*()
blk-mq: Embed counters into struct mq_inflight

block/blk-mq.c | 32 ++++++++------------------------
1 file changed, 8 insertions(+), 24 deletions(-)

--
2.23.0

2019-09-30 20:45:07

by Pavel Begunkov

[permalink] [raw]
Subject: [PATCH v2 1/2] blk-mq: Reuse callback in blk_mq_in_flight*()

From: Pavel Begunkov <[email protected]>

Reuse a more generic callback in both blk_mq_in_flight() and
blk_mq_in_flight_rw().

Signed-off-by: Pavel Begunkov <[email protected]>
---
block/blk-mq.c | 21 +++------------------
1 file changed, 3 insertions(+), 18 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index c4e5070c2ecd..3359a0b6c398 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -102,11 +102,8 @@ static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
{
struct mq_inflight *mi = priv;

- /*
- * index[0] counts the specific partition that was asked for.
- */
if (rq->part == mi->part)
- mi->inflight[0]++;
+ mi->inflight[rq_data_dir(rq)]++;

return true;
}
@@ -119,19 +116,7 @@ unsigned int blk_mq_in_flight(struct request_queue *q, struct hd_struct *part)
inflight[0] = inflight[1] = 0;
blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);

- return inflight[0];
-}
-
-static bool blk_mq_check_inflight_rw(struct blk_mq_hw_ctx *hctx,
- struct request *rq, void *priv,
- bool reserved)
-{
- struct mq_inflight *mi = priv;
-
- if (rq->part == mi->part)
- mi->inflight[rq_data_dir(rq)]++;
-
- return true;
+ return inflight[0] + inflight[1];
}

void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
@@ -140,7 +125,7 @@ void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
struct mq_inflight mi = { .part = part, .inflight = inflight, };

inflight[0] = inflight[1] = 0;
- blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight_rw, &mi);
+ blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
}

void blk_freeze_queue_start(struct request_queue *q)
--
2.23.0

2019-09-30 20:57:05

by Pavel Begunkov

[permalink] [raw]
Subject: [PATCH v2 2/2] blk-mq: Embed counters into struct mq_inflight

From: Pavel Begunkov <[email protected]>

Store inflight counters immediately in struct mq_inflight.
That's type-safer and removes extra indirection.

Signed-off-by: Pavel Begunkov <[email protected]>
---
block/blk-mq.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 3359a0b6c398..d97181d9a3ec 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -93,7 +93,7 @@ static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,

struct mq_inflight {
struct hd_struct *part;
- unsigned int *inflight;
+ unsigned int inflight[2];
};

static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
@@ -110,22 +110,21 @@ static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,

unsigned int blk_mq_in_flight(struct request_queue *q, struct hd_struct *part)
{
- unsigned inflight[2];
- struct mq_inflight mi = { .part = part, .inflight = inflight, };
+ struct mq_inflight mi = { .part = part };

- inflight[0] = inflight[1] = 0;
blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);

- return inflight[0] + inflight[1];
+ return mi.inflight[0] + mi.inflight[1];
}

void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
unsigned int inflight[2])
{
- struct mq_inflight mi = { .part = part, .inflight = inflight, };
+ struct mq_inflight mi = { .part = part };

- inflight[0] = inflight[1] = 0;
blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
+ inflight[0] = mi.inflight[0];
+ inflight[1] = mi.inflight[1];
}

void blk_freeze_queue_start(struct request_queue *q)
--
2.23.0

2019-10-02 06:34:39

by Jens Axboe

[permalink] [raw]
Subject: Re: [PATCH v2 0/2] Simplify blk_mq_in_flight*

On 9/30/19 12:55 PM, Pavel Begunkov (Silence) wrote:
> From: Pavel Begunkov <[email protected]>
>
> Clean up inflight counting code. Deduplicate it and fortify with types.
>
> v2: splitting the patch in two by Christoph suggestion

Looks good, applied, thanks.

--
Jens Axboe