linux-kernel - Re: [PATCH] f2fs: compress: fix to cover f2fs_disable_compressed_file() w/ i

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Date: Tue, 16 Jan 2024 10:29:23 -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] f2fs: compress: fix to cover
 f2fs_disable_compressed_file() w/ i_sem

On 01/11, Chao Yu wrote:
> - f2fs_disable_compressed_file
>   - check inode_has_data
> 					- f2fs_file_mmap
> 					- mkwrite
> 					 - f2fs_get_block_locked
> 					 : update metadata in compressed
> 					   inode's disk layout
>   - fi->i_flags &= ~F2FS_COMPR_FL
>   - clear_inode_flag(inode, FI_COMPRESSED_FILE);
> 
> we should use i_sem lock to prevent above race case.
> 
> Meanwhile, this patch adds i_size check to restrict compress inode
> conversion condition.

Sorry, what was the reason to check i_size?

> 
> Fixes: 4c8ff7095bef ("f2fs: support data compression")
> Signed-off-by: Chao Yu <chao@...nel.org>
> ---
>  fs/f2fs/f2fs.h | 18 ++++++++++++++++--
>  fs/f2fs/file.c |  5 ++---
>  2 files changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 74729db0b381..e2e0ca45f881 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -4406,19 +4406,33 @@ 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))
> +	f2fs_down_write(&F2FS_I(inode)->i_sem);
> +
> +	if (!f2fs_compressed_file(inode)) {
> +		f2fs_up_write(&F2FS_I(inode)->i_sem);
>  		return true;
> -	if (S_ISREG(inode->i_mode) && F2FS_HAS_BLOCKS(inode))
> +	}
> +	if (f2fs_is_mmap_file(inode) || inode_has_data(inode)) {
> +		f2fs_up_write(&F2FS_I(inode)->i_sem);
>  		return false;
> +	}
>  
>  	fi->i_flags &= ~F2FS_COMPR_FL;
>  	stat_dec_compr_inode(inode);
>  	clear_inode_flag(inode, FI_COMPRESSED_FILE);
>  	f2fs_mark_inode_dirty_sync(inode, true);
> +
> +	f2fs_up_write(&F2FS_I(inode)->i_sem);
>  	return true;
>  }
>  
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 0e4c871d6aed..5e5df234eb92 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -1926,8 +1926,7 @@ 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;
>  			}
> @@ -4011,7 +4010,7 @@ 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