Re: [PATCH 2/2] f2fs: introduce CP_TRIMMED_FLAG to avoid unneeded discard

[Jaegeuk Kim]

Hi Chao,

Could you add this state in print_cp_state() of f2fs-tools as well?

Thanks,

On 04/27, Chao Yu wrote:
> Introduce CP_TRIMMED_FLAG to indicate all invalid block were trimmed
> before umount, so once we do mount with image which contain the flag,
> we don't record invalid blocks as undiscard one, when fstrim is being
> triggered, we can avoid issuing redundant discard commands.
> 
> Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
> ---
>  fs/f2fs/checkpoint.c    |  3 +++
>  fs/f2fs/f2fs.h          |  1 +
>  fs/f2fs/segment.c       | 28 ++++++++++++++++++++--------
>  fs/f2fs/super.c         |  7 +++++++
>  include/linux/f2fs_fs.h |  1 +
>  5 files changed, 32 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 27578903eeb6..ea9c317b5916 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -1059,6 +1059,9 @@ static void update_ckpt_flags(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  			sbi->blocks_per_seg - NM_I(sbi)->nat_bits_blocks)
>  		disable_nat_bits(sbi, false);
>  
> +	if (cpc->reason & CP_TRIMMED)
> +		__set_ckpt_flags(ckpt, CP_TRIMMED_FLAG);
> +
>  	if (cpc->reason & CP_UMOUNT)
>  		__set_ckpt_flags(ckpt, CP_UMOUNT_FLAG);
>  	else
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 453eaa943a21..c6fce1631289 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -130,6 +130,7 @@ enum {
>  #define	CP_SYNC		0x00000004
>  #define	CP_RECOVERY	0x00000008
>  #define	CP_DISCARD	0x00000010
> +#define CP_TRIMMED	0x00000020
>  
>  #define DEF_BATCHED_TRIM_SECTIONS	2048
>  #define BATCHED_TRIM_SEGMENTS(sbi)	\
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index a2cd10cdff60..e4dd1e4a42c9 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -2989,10 +2989,17 @@ static void build_sit_entries(struct f2fs_sb_info *sbi)
>  
>  			/* build discard map only one time */
>  			if (f2fs_discard_en(sbi)) {
> -				memcpy(se->discard_map, se->cur_valid_map,
> -							SIT_VBLOCK_MAP_SIZE);
> -				sbi->discard_blks += sbi->blocks_per_seg -
> -							se->valid_blocks;
> +				if (is_set_ckpt_flags(sbi, CP_TRIMMED_FLAG)) {
> +					memset(se->discard_map, 0xff,
> +						SIT_VBLOCK_MAP_SIZE);
> +				} else {
> +					memcpy(se->discard_map,
> +						se->cur_valid_map,
> +						SIT_VBLOCK_MAP_SIZE);
> +					sbi->discard_blks +=
> +						sbi->blocks_per_seg -
> +						se->valid_blocks;
> +				}
>  			}
>  
>  			if (sbi->segs_per_sec > 1)
> @@ -3016,10 +3023,15 @@ static void build_sit_entries(struct f2fs_sb_info *sbi)
>  		seg_info_from_raw_sit(se, &sit);
>  
>  		if (f2fs_discard_en(sbi)) {
> -			memcpy(se->discard_map, se->cur_valid_map,
> -						SIT_VBLOCK_MAP_SIZE);
> -			sbi->discard_blks += old_valid_blocks -
> -						se->valid_blocks;
> +			if (is_set_ckpt_flags(sbi, CP_TRIMMED_FLAG)) {
> +				memset(se->discard_map, 0xff,
> +							SIT_VBLOCK_MAP_SIZE);
> +			} else {
> +				memcpy(se->discard_map, se->cur_valid_map,
> +							SIT_VBLOCK_MAP_SIZE);
> +				sbi->discard_blks += old_valid_blocks -
> +							se->valid_blocks;
> +			}
>  		}
>  
>  		if (sbi->segs_per_sec > 1)
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 4cd3bee6775f..9a14b2590337 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -797,6 +797,13 @@ static void f2fs_put_super(struct super_block *sb)
>  	/* be sure to wait for any on-going discard commands */
>  	f2fs_wait_discard_bios(sbi);
>  
> +	if (!sbi->discard_blks) {
> +		struct cp_control cpc = {
> +			.reason = CP_UMOUNT | CP_TRIMMED,
> +		};
> +		write_checkpoint(sbi, &cpc);
> +	}
> +
>  	/* write_checkpoint can update stat informaion */
>  	f2fs_destroy_stats(sbi);
>  
> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> index 093549e10ee2..b6feed6547ce 100644
> --- a/include/linux/f2fs_fs.h
> +++ b/include/linux/f2fs_fs.h
> @@ -114,6 +114,7 @@ struct f2fs_super_block {
>  /*
>   * For checkpoint
>   */
> +#define CP_TRIMMED_FLAG		0x00000100
>  #define CP_NAT_BITS_FLAG	0x00000080
>  #define CP_CRC_RECOVERY_FLAG	0x00000040
>  #define CP_FASTBOOT_FLAG	0x00000020
> -- 
> 2.12.2.510.ge1104a5ee539