linux-kernel - Re: [PATCH 2/2] f2fs: fix missing small discard in fstrim

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Message-ID: <e73ac805-b51e-4457-9f7d-7d3feaff32d8@kernel.org>
Date: Thu, 22 May 2025 19:11:14 +0800
From: Chao Yu <chao@...nel.org>
To: Chunhai Guo <guochunhai@...o.com>, jaegeuk@...nel.org
Cc: chao@...nel.org, linux-f2fs-devel@...ts.sourceforge.net,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] f2fs: fix missing small discard in fstrim

On 1/2/25 18:13, Chunhai Guo wrote:
> If userspace issues an fstrim with a range that does not include all
> segments with small discards, these segments will be reused without being
> discarded. This patch fixes this issue.
> This patch is somewhat similar to commit 650d3c4e56e1 ("f2fs: fix a missing
> discard prefree segments").

I guess it's better to update commit message as we discussed?

> 
> Fixes: d7bc2484b8d4 ("f2fs: fix small discards not to issue redundantly")
> Signed-off-by: Chunhai Guo <guochunhai@...o.com>
> ---
>  fs/f2fs/segment.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 8fe9f794b581..af9a62591c49 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -4552,6 +4552,8 @@ void f2fs_flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  	struct list_head *head = &SM_I(sbi)->sit_entry_set;
>  	bool to_journal = !is_sbi_flag_set(sbi, SBI_IS_RESIZEFS);
>  	struct seg_entry *se;
> +	bool force = (cpc->reason & CP_DISCARD);
> +	__u64 trim_start = cpc->trim_start;
>  
>  	down_write(&sit_i->sentry_lock);
>  
> @@ -4609,7 +4611,9 @@ void f2fs_flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  #endif
>  
>  			/* add discard candidates */
> -			if (!(cpc->reason & CP_DISCARD)) {
> +			if (!force || (force &&

if (!force || (f2fs_realtime_discard_enable() &&
		(segno < trim_start || segno > trim_end)))

Thanks,

> +					(segno < trim_start ||
> +					 segno > cpc->trim_end))) {
>  				cpc->trim_start = segno;
>  				add_discard_addrs(sbi, cpc, false, false);
>  			}
> @@ -4649,8 +4653,8 @@ void f2fs_flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  	f2fs_bug_on(sbi, !list_empty(head));
>  	f2fs_bug_on(sbi, sit_i->dirty_sentries);
>  out:
> -	if (cpc->reason & CP_DISCARD) {
> -		__u64 trim_start = cpc->trim_start;
> +	if (force) {
> +		cpc->trim_start = trim_start;
>  
>  		for (; cpc->trim_start <= cpc->trim_end; cpc->trim_start++)
>  			add_discard_addrs(sbi, cpc, true, false);