Re: [PATCH] f2fs: compress: don't force buffered io when in COMPR_MODE_USER mode

[Chao Yu]

On 2023/6/9 21:15, Yangtao Li wrote:
> It is observed that when in user compression mode (compress_extension=*),
> even though the file is not compressed, the file is still forced to use
> buffer io, which makes the AndroBench sequential read and write drop
> significantly. In fact, when the file is not compressed, we don't need
> to force it to buffer io.
>
>                   | w/o patch | w/ patch |
> seq read  (MB/s) | 1320.068  | 3696.154 |
> seq write (MB/s) | 617.996   | 2978.478 |
>
> Fixes: 4c8ff7095bef ("f2fs: support data compression")
> Signed-off-by: Qi Han <hanqi@xxxxxxxx>
> Signed-off-by: Yangtao Li <frank.li@xxxxxxxx>
> ---
>   fs/f2fs/f2fs.h | 14 ++++++++++++++
>   fs/f2fs/file.c |  2 +-
>   2 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 1efcfd9e5a99..7f5472525310 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -3168,6 +3168,20 @@ static inline int f2fs_compressed_file(struct inode *inode)
>   		is_inode_flag_set(inode, FI_COMPRESSED_FILE);
>   }
>   
> +static inline bool f2fs_is_compressed_file(struct inode *inode)
> +{
> +	int compress_mode = F2FS_OPTION(F2FS_I_SB(inode)).compress_mode;
> +
> +	if (compress_mode == COMPR_MODE_FS)
> +		return f2fs_compressed_file(inode);
> +	else if (atomic_read(&F2FS_I(inode)->i_compr_blocks) ||

Should check dirty page as well? i_compr_blocks may increase after
data writeback.

Thanks,

> +		is_inode_flag_set(inode, FI_COMPRESS_RELEASED) ||
> +		is_inode_flag_set(inode, FI_ENABLE_COMPRESS))
> +		return true;
> +
> +	return false;
> +}
> +
>   static inline bool f2fs_need_compress_data(struct inode *inode)
>   {
>   	int compress_mode = F2FS_OPTION(F2FS_I_SB(inode)).compress_mode;
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 74ecc9e20619..0698129b2165 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -821,7 +821,7 @@ static bool f2fs_force_buffered_io(struct inode *inode, int rw)
>   		return true;
>   	if (fsverity_active(inode))
>   		return true;
> -	if (f2fs_compressed_file(inode))
> +	if (f2fs_is_compressed_file(inode))
>   		return true;
>   
>   	/* disallow direct IO if any of devices has unaligned blksize */