Re: [PATCH 1/2] f2fs: fix a missing discard prefree segments

[Jaegeuk Kim <jaegeuk@kernel.org>]

Hi Yunlei,

On 12/16, Yunlei He wrote:
> If userspace issue a fstrim with a range not involve prefree segments,
> it will reuse these segments without discard. This patch fix it.
> 
> Signed-off-by: Yunlei He <heyunlei@huawei.com>
> ---
>  fs/f2fs/segment.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index d7d5727..5b4468f 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -899,6 +899,9 @@ void clear_prefree_segments(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  	unsigned int secno, start_segno;
>  	bool force = (cpc->reason == CP_DISCARD);
>  
> +	if (!test_opt(sbi, DISCARD))
> +		return;

We need to clear the prefree bits, even if discard option was not set.

> +
>  	blk_start_plug(&plug);
>  
>  	mutex_lock(&dirty_i->seglist_lock);
> @@ -910,15 +913,15 @@ void clear_prefree_segments(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  			break;
>  		end = find_next_zero_bit(prefree_map, MAIN_SEGS(sbi),
>  								start + 1);
> +		if (force && start * sbi->blocks_per_seg >= cpc->trim_start &&
> +					end * sbi->blocks_per_seg <= cpc->trim_end)
> +			continue;

ditto.

>  
>  		for (i = start; i < end; i++)
>  			clear_bit(i, prefree_map);
>  
>  		dirty_i->nr_dirty[PRE] -= end - start;
>  
> -		if (force || !test_opt(sbi, DISCARD))
> -			continue;

Why not just adding that condition here?

Thanks,

> -
>  		if (!test_opt(sbi, LFS) || sbi->segs_per_sec == 1) {
>  			f2fs_issue_discard(sbi, START_BLOCK(sbi, start),
>  				(end - start) << sbi->log_blocks_per_seg);
> -- 
> 2.10.1
> 
> 
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