linux-kernel - Re: [PATCH v2] f2fs: restrict write IO alignment condition

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Date:   Mon, 13 Mar 2017 13:05:44 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, chao@...nel.org
Subject: Re: [PATCH v2] f2fs: restrict write IO alignment condition

On 03/13, Chao Yu wrote:
> We should only align start offset of bio with defined IO_SIZE for below
> conditions:
> a. mode=lfs mount option
> b. write IOs
> c. Out-place-update
> d. non-meta pages
> 
> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> ---
>  fs/f2fs/data.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 1375fef11146..53fe79c70406 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -190,6 +190,9 @@ static inline void __submit_bio(struct f2fs_sb_info *sbi,
>  			current->plug && (type == DATA || type == NODE))
>  			blk_finish_plug(current->plug);
>  
> +		if (!test_opt(sbi, LFS))
> +			goto submit_io;

The parse_options in fill_super checks this.

> +
>  		if (type != DATA && type != NODE)
>  			goto submit_io;
>  
> @@ -395,11 +398,12 @@ int f2fs_submit_page_mbio(struct f2fs_io_info *fio)
>  		__submit_merged_bio(io);
>  alloc_new:
>  	if (io->bio == NULL) {
> -		if ((fio->type == DATA || fio->type == NODE) &&
> +		if (test_opt(sbi, LFS) &&
> +			!is_read && (fio->type == DATA || fio->type == NODE) &&

The missing case is !is_read, here?
But, actually, DATA and NODE don't issue any read commands at all.

Thanks,

>  				fio->new_blkaddr & F2FS_IO_SIZE_MASK(sbi)) {
>  			err = -EAGAIN;
> -			if (!is_read)
> -				dec_page_count(sbi, WB_DATA_TYPE(bio_page));
> +			f2fs_bug_on(sbi, fio->new_blkaddr == fio->old_blkaddr);
> +			dec_page_count(sbi, WB_DATA_TYPE(bio_page));
>  			goto out_fail;
>  		}
>  		io->bio = __bio_alloc(sbi, fio->new_blkaddr,
> -- 
> 2.8.2.295.g3f1c1d0