[PATCH] block: cleanup the VM accounting in submit_bio

[PATCH] block: cleanup the VM accounting in submit_bio

[Christoph Hellwig]

submit_bio uses some extremely convoluted checks and confusing comments
to only account REQ_OP_READ/REQ_OP_WRITE comments.  Just switch to the
plain obvious checks instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-core.c | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index ee18b6a699bdf..48a58c24d452e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -893,19 +893,11 @@ void submit_bio(struct bio *bio)
 	if (blkcg_punt_bio_submit(bio))
 		return;
 
-	/*
-	 * If it's a regular read/write or a barrier with data attached,
-	 * go through the normal accounting stuff before submission.
-	 */
-	if (bio_has_data(bio)) {
-		unsigned int count = bio_sectors(bio);
-
-		if (op_is_write(bio_op(bio))) {
-			count_vm_events(PGPGOUT, count);
-		} else {
-			task_io_account_read(bio->bi_iter.bi_size);
-			count_vm_events(PGPGIN, count);
-		}
+	if (bio_op(bio) == REQ_OP_READ) {
+		task_io_account_read(bio->bi_iter.bi_size);
+		count_vm_events(PGPGIN, bio_sectors(bio));
+	} else if (bio_op(bio) == WRITE) {
+		count_vm_events(PGPGOUT, bio_sectors(bio));
 	}
 
 	/*
-- 
2.30.2

Re: [PATCH] block: cleanup the VM accounting in submit_bio

[Jens Axboe]

On Mon, 16 May 2022 08:36:54 +0200, Christoph Hellwig wrote:
> submit_bio uses some extremely convoluted checks and confusing comments
> to only account REQ_OP_READ/REQ_OP_WRITE comments.  Just switch to the
> plain obvious checks instead.
> 
> 

Applied, thanks!

[1/1] block: cleanup the VM accounting in submit_bio
      commit: b1ec1bae3b425e145e134fd63347576c478b85db

Best regards,
-- 
Jens Axboe

Re: [PATCH] block: cleanup the VM accounting in submit_bio

[Damien Le Moal]

On 2022/05/16 8:36, Christoph Hellwig wrote:
> submit_bio uses some extremely convoluted checks and confusing comments
> to only account REQ_OP_READ/REQ_OP_WRITE comments.  Just switch to the
> plain obvious checks instead.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  block/blk-core.c | 18 +++++-------------
>  1 file changed, 5 insertions(+), 13 deletions(-)
> 
> diff --git a/block/blk-core.c b/block/blk-core.c
> index ee18b6a699bdf..48a58c24d452e 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -893,19 +893,11 @@ void submit_bio(struct bio *bio)
>  	if (blkcg_punt_bio_submit(bio))
>  		return;
>  
> -	/*
> -	 * If it's a regular read/write or a barrier with data attached,
> -	 * go through the normal accounting stuff before submission.
> -	 */
> -	if (bio_has_data(bio)) {
> -		unsigned int count = bio_sectors(bio);
> -
> -		if (op_is_write(bio_op(bio))) {
> -			count_vm_events(PGPGOUT, count);
> -		} else {
> -			task_io_account_read(bio->bi_iter.bi_size);
> -			count_vm_events(PGPGIN, count);
> -		}
> +	if (bio_op(bio) == REQ_OP_READ) {
> +		task_io_account_read(bio->bi_iter.bi_size);
> +		count_vm_events(PGPGIN, bio_sectors(bio));
> +	} else if (bio_op(bio) == WRITE) {

I know it is the same value, but for consistency, wouldn't it be better to use
REQ_OP_WRITE here ?

> +		count_vm_events(PGPGOUT, bio_sectors(bio));
>  	}
>  
>  	/*


-- 
Damien Le Moal
Western Digital Research

Re: [PATCH] block: cleanup the VM accounting in submit_bio

[Christoph Hellwig]

On Mon, May 16, 2022 at 03:45:08PM +0200, Damien Le Moal wrote:
> I know it is the same value, but for consistency, wouldn't it be better to use
> REQ_OP_WRITE here ?

Yes, it absolutely would.  The use of WRITE wasn't even initentional.

Re: [PATCH] block: cleanup the VM accounting in submit_bio

[Jens Axboe]

On 5/16/22 8:11 AM, Christoph Hellwig wrote:
> On Mon, May 16, 2022 at 03:45:08PM +0200, Damien Le Moal wrote:
>> I know it is the same value, but for consistency, wouldn't it be better to use
>> REQ_OP_WRITE here ?
> 
> Yes, it absolutely would.  The use of WRITE wasn't even initentional.

I'll fix it up.

-- 
Jens Axboe