linux-kernel - Re: [PATCH V2 1/2] erofs: use kmemdup_nul in erofs_fill

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Message-ID: <bfcd83f8-87ef-4282-b9e9-700c45fc3302@linux.alibaba.com>
Date: Mon, 2 Sep 2024 15:11:45 +0800
From: Gao Xiang <hsiangkao@...ux.alibaba.com>
To: Yiyang Wu <toolmanp@...p.cc>
Cc: linux-erofs@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
 Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH V2 1/2] erofs: use kmemdup_nul in erofs_fill_symlink



On 2024/9/2 15:00, Yiyang Wu via Linux-erofs wrote:
> Remove open coding in erofs_fill_symlink.
> 
> Suggested-by: Al Viro <viro@...iv.linux.org.uk>
> Link: https://lore.kernel.org/all/20240425222847.GN2118490@ZenIV
> Signed-off-by: Yiyang Wu <toolmanp@...p.cc>
> ---
>   fs/erofs/inode.c | 12 +++++-------
>   1 file changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
> index 419432be3223..d051afe39670 100644
> --- a/fs/erofs/inode.c
> +++ b/fs/erofs/inode.c
> @@ -188,22 +188,20 @@ static int erofs_fill_symlink(struct inode *inode, void *kaddr,
>   		return 0;
>   	}
>   
> -	lnk = kmalloc(inode->i_size + 1, GFP_KERNEL);
> -	if (!lnk)
> -		return -ENOMEM;
> -
>   	m_pofs += vi->xattr_isize;
>   	/* inline symlink data shouldn't cross block boundary */
>   	if (m_pofs + inode->i_size > bsz) {
> -		kfree(lnk);
>   		erofs_err(inode->i_sb,
>   			  "inline data cross block boundary @ nid %llu",
>   			  vi->nid);
>   		DBG_BUGON(1);
>   		return -EFSCORRUPTED;
>   	}
> -	memcpy(lnk, kaddr + m_pofs, inode->i_size);
> -	lnk[inode->i_size] = '\0';
> +
> +	lnk = kmemdup_nul(kaddr + m_pofs, inode->i_size, GFP_KERNEL);
> +

Unnecessary new line.

Also I wonder if it's possible to just
	inode->i_link = kmemdup_nul(kaddr + m_pofs, inode->i_size, GFP_KERNEL);
	if (!inode->i_link)
		return -ENOMEM;

here, and get rid of variable lnk.

Otherwise it looks good to me.

Thanks,
Gao Xiang

> +	if (!lnk)
> +		return -ENOMEM;
>   
>   	inode->i_link = lnk;
>   	inode->i_op = &erofs_fast_symlink_iops;