linux-kernel - Re: [PATCH 5/6] f2fs: fix to restrict condition of compress inode conversion

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Message-ID: <ZXeJKCNrxcit0eTC@google.com>
Date:   Mon, 11 Dec 2023 14:11:52 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <chao@...nel.org>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/6] f2fs: fix to restrict condition of compress inode
 conversion

On 12/10, Chao Yu wrote:
> This patch adds i_size check during compress inode conversion in order
> to avoid .page_mkwrite races w/ conversion.

Which race condition do you see?

> 
> Fixes: 4c8ff7095bef ("f2fs: support data compression")
> Signed-off-by: Chao Yu <chao@...nel.org>
> ---
>  fs/f2fs/f2fs.h | 8 +++++++-
>  fs/f2fs/file.c | 5 ++---
>  2 files changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 65294e3b0bef..c9b8a1953913 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -4397,13 +4397,19 @@ static inline int set_compress_context(struct inode *inode)
>  #endif
>  }
>  
> +static inline bool inode_has_data(struct inode *inode)
> +{
> +	return (S_ISREG(inode->i_mode) &&
> +		(F2FS_HAS_BLOCKS(inode) || i_size_read(inode)));
> +}
> +
>  static inline bool f2fs_disable_compressed_file(struct inode *inode)
>  {
>  	struct f2fs_inode_info *fi = F2FS_I(inode);
>  
>  	if (!f2fs_compressed_file(inode))
>  		return true;
> -	if (S_ISREG(inode->i_mode) && F2FS_HAS_BLOCKS(inode))
> +	if (inode_has_data(inode))
>  		return false;
>  
>  	fi->i_flags &= ~F2FS_COMPR_FL;
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 1a3c29a9a6a0..8af4b29c3e1a 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -1922,8 +1922,7 @@ static int f2fs_setflags_common(struct inode *inode, u32 iflags, u32 mask)
>  
>  			f2fs_down_write(&F2FS_I(inode)->i_sem);
>  			if (!f2fs_may_compress(inode) ||
> -					(S_ISREG(inode->i_mode) &&
> -					F2FS_HAS_BLOCKS(inode))) {
> +					inode_has_data(inode)) {
>  				f2fs_up_write(&F2FS_I(inode)->i_sem);
>  				return -EINVAL;
>  			}
> @@ -3996,7 +3995,7 @@ static int f2fs_ioc_set_compress_option(struct file *filp, unsigned long arg)
>  		goto out;
>  	}
>  
> -	if (F2FS_HAS_BLOCKS(inode)) {
> +	if (inode_has_data(inode)) {
>  		ret = -EFBIG;
>  		goto out;
>  	}
> -- 
> 2.40.1