linux-kernel - RE: [PATCH 1/2 v2] exfat: write multiple sectors at once

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Date:   Tue, 9 Jun 2020 17:49:37 +0900
From:   "Namjae Jeon" <namjae.jeon@...sung.com>
To:     "'Tetsuhiro Kohada'" <kohada.t2@...il.com>
Cc:     <kohada.tetsuhiro@...mitsubishielectric.co.jp>,
        <mori.takahiro@...mitsubishielectric.co.jp>,
        <motai.hirotaka@...mitsubishielectric.co.jp>,
        "'Namjae Jeon'" <linkinjeon@...nel.org>,
        "'Sungjong Seo'" <sj1557.seo@...sung.com>,
        <linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/2 v2] exfat: write multiple sectors at once

> Write multiple sectors at once when updating dir-entries.
> Add exfat_update_bhs() for that. It wait for write completion once instead of sector by sector.
> It's only effective if sync enabled.
> 
> Suggested-by: Namjae Jeon <linkinjeon@...nel.org>
> Signed-off-by: Tetsuhiro Kohada <kohada.t2@...il.com>
> ---
> Changes in v2:
>  - Split into 'write multiple sectors at once'
>    and 'add error check when updating dir-entries'
> 
>  fs/exfat/dir.c      | 12 +++++++-----
>  fs/exfat/exfat_fs.h |  1 +
>  fs/exfat/misc.c     | 19 +++++++++++++++++++
>  3 files changed, 27 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c index de43534aa299..495884ccb352 100644
> --- a/fs/exfat/dir.c
> +++ b/fs/exfat/dir.c
> @@ -604,13 +604,15 @@ void exfat_update_dir_chksum_with_entry_set(struct exfat_entry_set_cache *es)
> 
>  void exfat_free_dentry_set(struct exfat_entry_set_cache *es, int sync)  {
> -	int i;
> +	int i, err = 0;
> 
> -	for (i = 0; i < es->num_bh; i++) {
> -		if (es->modified)
> -			exfat_update_bh(es->sb, es->bh[i], sync);
> -		brelse(es->bh[i]);
> +	if (es->modified) {
> +		set_bit(EXFAT_SB_DIRTY, &EXFAT_SB(es->sb)->s_state);
I pointed out that setting EXFAT_SB_DIRTY can be merged into exfat_update_bhs() on previous thread.
Is it unnecessary?
> +		err = exfat_update_bhs(es->bh, es->num_bh, sync);
>  	}
> +
> +	for (i = 0; i < es->num_bh; i++)
> +		err ? bforget(es->bh[i]):brelse(es->bh[i]);
>  	kfree(es);
>  }
> 
> diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h index 595f3117f492..935954da2e54 100644
> --- a/fs/exfat/exfat_fs.h
> +++ b/fs/exfat/exfat_fs.h
> @@ -515,6 +515,7 @@ void exfat_set_entry_time(struct exfat_sb_info *sbi, struct timespec64 *ts,
>  u16 exfat_calc_chksum16(void *data, int len, u16 chksum, int type);
>  u32 exfat_calc_chksum32(void *data, int len, u32 chksum, int type);  void exfat_update_bh(struct
> super_block *sb, struct buffer_head *bh, int sync);
> +int exfat_update_bhs(struct buffer_head **bhs, int nr_bhs, int sync);
>  void exfat_chain_set(struct exfat_chain *ec, unsigned int dir,
>  		unsigned int size, unsigned char flags);  void exfat_chain_dup(struct exfat_chain *dup,
> struct exfat_chain *ec); diff --git a/fs/exfat/misc.c b/fs/exfat/misc.c index
> 17d41f3d3709..dc34968e99d3 100644
> --- a/fs/exfat/misc.c
> +++ b/fs/exfat/misc.c
> @@ -173,6 +173,25 @@ void exfat_update_bh(struct super_block *sb, struct buffer_head *bh, int sync)
>  		sync_dirty_buffer(bh);
>  }
> 
> +int exfat_update_bhs(struct buffer_head **bhs, int nr_bhs, int sync) {
> +	int i, err = 0;
> +
> +	for (i = 0; i < nr_bhs; i++) {
> +		set_buffer_uptodate(bhs[i]);
> +		mark_buffer_dirty(bhs[i]);
> +		if (sync)
> +			write_dirty_buffer(bhs[i], 0);
> +	}
> +
> +	for (i = 0; i < nr_bhs && sync; i++) {
> +		wait_on_buffer(bhs[i]);
> +		if (!buffer_uptodate(bhs[i]))
> +			err = -EIO;
> +	}
> +	return err;
> +}
> +
>  void exfat_chain_set(struct exfat_chain *ec, unsigned int dir,
>  		unsigned int size, unsigned char flags)  {
> --
> 2.25.1