linux-kernel - Re: [f2fs-dev] [PATCH 2/2] f2fs: keep io_flags to avoid IO split due to different op

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Date:   Sun, 17 Apr 2022 14:55:12 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 2/2] f2fs: keep io_flags to avoid IO split due
 to different op_flags in two fio holders

On 2022/4/13 23:49, Jaegeuk Kim wrote:
> Let's attach io_flags to bio only, so that we can merge IOs given original
> io_flags only.
> 
> Fixes: 64bf0eef0171 ("f2fs: pass the bio operation to bio_alloc_bioset")

Nice catch.

Wasn't this bug introduced by:

commit da9953b729c1 ("f2fs: introduce sysfs/data_io_flag to attach REQ_META/FUA")

static void __attach_data_io_flag(struct f2fs_io_info *fio)
{
...
        if ((1 << fio->temp) & meta_flag)
                fio->op_flags |= REQ_META;
        if ((1 << fio->temp) & fua_flag)
                fio->op_flags |= REQ_FUA;
...

Thanks,

> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> ---
>   fs/f2fs/data.c | 33 +++++++++++++++++++++------------
>   1 file changed, 21 insertions(+), 12 deletions(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index acc523f893ba..fcf0daa386de 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -387,11 +387,23 @@ int f2fs_target_device_index(struct f2fs_sb_info *sbi, block_t blkaddr)
>   	return 0;
>   }
>   
> -static void __attach_io_flag(struct f2fs_io_info *fio, unsigned int io_flag)
> +static unsigned int f2fs_io_flags(struct f2fs_io_info *fio)
>   {
>   	unsigned int temp_mask = (1 << NR_TEMP_TYPE) - 1;
> -	unsigned int fua_flag = io_flag & temp_mask;
> -	unsigned int meta_flag = (io_flag >> NR_TEMP_TYPE) & temp_mask;
> +	unsigned int fua_flag, meta_flag, io_flag;
> +	unsigned int op_flags = 0;
> +
> +	if (fio->op != REQ_OP_WRITE)
> +		return 0;
> +	if (fio->type == DATA)
> +		io_flag = fio->sbi->data_io_flag;
> +	else if (fio->type == NODE)
> +		io_flag = fio->sbi->node_io_flag;
> +	else
> +		return 0;
> +
> +	fua_flag = io_flag & temp_mask;
> +	meta_flag = (io_flag >> NR_TEMP_TYPE) & temp_mask;
>   
>   	/*
>   	 * data/node io flag bits per temp:
> @@ -400,9 +412,10 @@ static void __attach_io_flag(struct f2fs_io_info *fio, unsigned int io_flag)
>   	 * Cold | Warm | Hot | Cold | Warm | Hot |
>   	 */
>   	if ((1 << fio->temp) & meta_flag)
> -		fio->op_flags |= REQ_META;
> +		op_flags |= REQ_META;
>   	if ((1 << fio->temp) & fua_flag)
> -		fio->op_flags |= REQ_FUA;
> +		op_flags |= REQ_FUA;
> +	return op_flags;
>   }
>   
>   static struct bio *__bio_alloc(struct f2fs_io_info *fio, int npages)
> @@ -412,14 +425,10 @@ static struct bio *__bio_alloc(struct f2fs_io_info *fio, int npages)
>   	sector_t sector;
>   	struct bio *bio;
>   
> -	if (fio->type == DATA)
> -		__attach_io_flag(fio, sbi->data_io_flag);
> -	else if (fio->type == NODE)
> -		__attach_io_flag(fio, sbi->node_io_flag);
> -
>   	bdev = f2fs_target_device(sbi, fio->new_blkaddr, &sector);
> -	bio = bio_alloc_bioset(bdev, npages, fio->op | fio->op_flags, GFP_NOIO,
> -			       &f2fs_bioset);
> +	bio = bio_alloc_bioset(bdev, npages,
> +				fio->op | fio->op_flags | f2fs_io_flags(fio),
> +				GFP_NOIO, &f2fs_bioset);
>   	bio->bi_iter.bi_sector = sector;
>   	if (is_read_io(fio->op)) {
>   		bio->bi_end_io = f2fs_read_end_io;