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

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Date:   Mon, 13 Mar 2017 21:45:08 +0800
From:   Kinglong Mee <kinglongmee@...il.com>
To:     Chao Yu <yuchao0@...wei.com>, jaegeuk@...nel.org
Cc:     chao@...nel.org, linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        Kinglong Mee <kinglongmee@...il.com>
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: restrict write IO alignment condition

On 3/13/2017 21:02, 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;
> +
>  		if (type != DATA && type != NODE)
>  			goto submit_io;

Is the position of checking LFS here right?

I have a plan of change the code order as, 
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 2ab5ca0..698dbf3 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -186,13 +186,12 @@ static inline void __submit_bio(struct f2fs_sb_info *sbi,
        if (!is_read_io(bio_op(bio))) {
                unsigned int start;

-               if (f2fs_sb_mounted_blkzoned(sbi->sb) &&
-                       current->plug && (type == DATA || type == NODE))
-                       blk_finish_plug(current->plug);
-
                if (type != DATA && type != NODE)
                        goto submit_io;

+               if (f2fs_sb_mounted_blkzoned(sbi->sb) && current->plug)
+                       blk_finish_plug(current->plug);
+
                start = bio->bi_iter.bi_size >> F2FS_BLKSIZE_BITS;
                start %= F2FS_IO_SIZE(sbi);

thanks,
Kinglong Mee

>  
> @@ -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) &&
>  				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,
>