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Subject: Re: [f2fs-dev] [PATCH] f2fs: ignore when len of range in
 f2fs_sec_trim_file is zero
To:     Daeho Jeong <daeho43@gmail.com>, <linux-kernel@vger.kernel.org>,
        <linux-f2fs-devel@lists.sourceforge.net>, <kernel-team@android.com>
CC:     Daeho Jeong <daehojeong@google.com>
References: <20200709015739.1653668-1-daeho43@gmail.com>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <619af72b-2f8a-4a84-f73e-ac49989ba79f@huawei.com>
Date:   Thu, 9 Jul 2020 11:05:15 +0800
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On 2020/7/9 9:57, Daeho Jeong wrote:
> From: Daeho Jeong <daehojeong@google.com>
> 
> When end_addr comes to zero, it'll trigger different behaviour.
> To prevent this, we need to ignore the case of that range.len is
> zero in the function.
> 
> Signed-off-by: Daeho Jeong <daehojeong@google.com>
> ---
>  fs/f2fs/file.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 368c80f8e2a1..98b0a8dbf669 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -3813,15 +3813,14 @@ static int f2fs_sec_trim_file(struct file *filp, unsigned long arg)
>  	file_start_write(filp);
>  	inode_lock(inode);
>  
> -	if (f2fs_is_atomic_file(inode) || f2fs_compressed_file(inode)) {
> +	if (f2fs_is_atomic_file(inode) || f2fs_compressed_file(inode) ||
> +			range.start >= inode->i_size) {
>  		ret = -EINVAL;
>  		goto err;
>  	}
>  
> -	if (range.start >= inode->i_size) {
> -		ret = -EINVAL;
> +	if (range.len == 0)
>  		goto err;
> -	}
>  
>  	if (inode->i_size - range.start < range.len) {
>  		ret = -E2BIG;

How about the case trimming last partial written block?

i_size = 8000
range.start = 4096
range.len = 4096

Do we need to roundup(isize, PAGE_SIZE) before comparison?

Thanks,

>