linux-kernel - Re: [PATCH V3 5/6] f2fs: ignore discard return value

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Message-ID: <09e48eba-6f00-455a-8299-8b8bb4122c7e@kernel.org>
Date: Wed, 26 Nov 2025 10:47:35 +0800
From: Chao Yu <chao@...nel.org>
To: Chaitanya Kulkarni <ckulkarnilinux@...il.com>, axboe@...nel.dk,
 agk@...hat.com, snitzer@...nel.org, mpatocka@...hat.com, song@...nel.org,
 yukuai@...as.com, hch@....de, sagi@...mberg.me, kch@...dia.com,
 jaegeuk@...nel.org, cem@...nel.org
Cc: chao@...nel.org, linux-block@...r.kernel.org,
 linux-kernel@...r.kernel.org, dm-devel@...ts.linux.dev,
 linux-raid@...r.kernel.org, linux-nvme@...ts.infradead.org,
 linux-f2fs-devel@...ts.sourceforge.net, linux-xfs@...r.kernel.org,
 bpf@...r.kernel.org, "Martin K . Petersen" <martin.petersen@...cle.com>,
 Johannes Thumshirn <johannes.thumshirn@....com>
Subject: Re: [PATCH V3 5/6] f2fs: ignore discard return value

On 11/25/25 07:48, Chaitanya Kulkarni wrote:
> __blkdev_issue_discard() always returns 0, making the error assignment
> in __submit_discard_cmd() dead code.
> 
> Initialize err to 0 and remove the error assignment from the
> __blkdev_issue_discard() call to err. Move fault injection code into
> already present if branch where err is set to -EIO.
> 
> This preserves the fault injection behavior while removing dead error
> handling.
> 
> Reviewed-by: Martin K. Petersen <martin.petersen@...cle.com>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@....com>
> Reviewed-by: Christoph Hellwig <hch@....de>
> Signed-off-by: Chaitanya Kulkarni <ckulkarnilinux@...il.com>
> ---
>  fs/f2fs/segment.c | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index b45eace879d7..22b736ec9c51 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1343,15 +1343,9 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
>  
>  		dc->di.len += len;
>  
> +		err = 0;
>  		if (time_to_inject(sbi, FAULT_DISCARD)) {
>  			err = -EIO;
> -		} else {
> -			err = __blkdev_issue_discard(bdev,
> -					SECTOR_FROM_BLOCK(start),
> -					SECTOR_FROM_BLOCK(len),
> -					GFP_NOFS, &bio);
> -		}
> -		if (err) {
>  			spin_lock_irqsave(&dc->lock, flags);
>  			if (dc->state == D_PARTIAL)
>  				dc->state = D_SUBMIT;
> @@ -1360,6 +1354,8 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
>  			break;
>  		}
>  
> +		__blkdev_issue_discard(bdev, SECTOR_FROM_BLOCK(start),
> +				SECTOR_FROM_BLOCK(len), GFP_NOFS, &bio);

Oh, wait, bio can be NULL? Then below f2fs_bug_on() will trigger panic or warning.

Thanks,

>  		f2fs_bug_on(sbi, !bio);
>  
>  		/*