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Date:   Mon, 2 Nov 2020 08:31:23 -0800
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <yuchao0@huawei.com>
Cc:     linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, chao@kernel.org
Subject: Re: [PATCH] f2fs: compress: support chksum
Message-ID: <20201102163123.GD529594@google.com>
References: <20201102122333.76667-1-yuchao0@huawei.com>
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In-Reply-To: <20201102122333.76667-1-yuchao0@huawei.com>
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On 11/02, Chao Yu wrote:
> This patch supports to store chksum value with compressed
> data, and verify the integrality of compressed data while
> reading the data.
> 
> The feature can be enabled through specifying mount option
> 'compress_chksum'.
> 
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> ---
>  Documentation/filesystems/f2fs.rst |  1 +
>  fs/f2fs/compress.c                 | 20 ++++++++++++++++++++
>  fs/f2fs/f2fs.h                     | 13 ++++++++++++-
>  fs/f2fs/inode.c                    |  3 +++
>  fs/f2fs/super.c                    |  9 +++++++++
>  include/linux/f2fs_fs.h            |  2 +-
>  6 files changed, 46 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
> index b8ee761c9922..985ae7d35066 100644
> --- a/Documentation/filesystems/f2fs.rst
> +++ b/Documentation/filesystems/f2fs.rst
> @@ -260,6 +260,7 @@ compress_extension=%s	 Support adding specified extension, so that f2fs can enab
>  			 For other files, we can still enable compression via ioctl.
>  			 Note that, there is one reserved special extension '*', it
>  			 can be set to enable compression for all files.
> +compress_chksum		 Support verifying chksum of raw data in compressed cluster.
>  inlinecrypt		 When possible, encrypt/decrypt the contents of encrypted
>  			 files using the blk-crypto framework rather than
>  			 filesystem-layer encryption. This allows the use of
> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
> index 14262e0f1cd6..a4e0d2c745b6 100644
> --- a/fs/f2fs/compress.c
> +++ b/fs/f2fs/compress.c
> @@ -602,6 +602,7 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
>  				f2fs_cops[fi->i_compress_algorithm];
>  	unsigned int max_len, new_nr_cpages;
>  	struct page **new_cpages;
> +	u32 chksum = 0;
>  	int i, ret;
>  
>  	trace_f2fs_compress_pages_start(cc->inode, cc->cluster_idx,
> @@ -655,6 +656,11 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
>  
>  	cc->cbuf->clen = cpu_to_le32(cc->clen);
>  
> +	if (fi->i_compress_flag & 1 << COMPRESS_CHKSUM)
> +		chksum = f2fs_crc32(F2FS_I_SB(cc->inode),
> +					cc->cbuf->cdata, cc->clen);
> +	cc->cbuf->chksum = cpu_to_le32(chksum);
> +
>  	for (i = 0; i < COMPRESS_DATA_RESERVED_SIZE; i++)
>  		cc->cbuf->reserved[i] = cpu_to_le32(0);
>  
> @@ -721,6 +727,7 @@ void f2fs_decompress_pages(struct bio *bio, struct page *page, bool verity)
>  			(struct decompress_io_ctx *)page_private(page);
>  	struct f2fs_sb_info *sbi = F2FS_I_SB(dic->inode);
>  	struct f2fs_inode_info *fi= F2FS_I(dic->inode);
> +	struct f2fs_sb_info *sbi = F2FS_I_SB(dic->inode);
>  	const struct f2fs_compress_ops *cops =
>  			f2fs_cops[fi->i_compress_algorithm];
>  	int ret;
> @@ -790,6 +797,19 @@ void f2fs_decompress_pages(struct bio *bio, struct page *page, bool verity)
>  
>  	ret = cops->decompress_pages(dic);
>  
> +	if (!ret && fi->i_compress_flag & 1 << COMPRESS_CHKSUM) {
> +		u32 provided = le32_to_cpu(dic->cbuf->chksum);
> +		u32 calculated = f2fs_crc32(sbi, dic->cbuf->cdata, dic->clen);
> +
> +		if (provided != calculated) {
> +			printk_ratelimited(
> +				"%sF2FS-fs (%s): checksum invalid, nid = %lu, %x vs %x",
> +				KERN_INFO, sbi->sb->s_id, dic->inode->i_ino,
> +				provided, calculated);
> +			ret = -EFSCORRUPTED;

Do we need to change fsck.f2fs to recover this?

> +		}
> +	}
> +
>  out_vunmap_cbuf:
>  	vm_unmap_ram(dic->cbuf, dic->nr_cpages);
>  out_vunmap_rbuf:
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 99bcf4b44a9c..2ae254ab7b7d 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -147,7 +147,8 @@ struct f2fs_mount_info {
>  
>  	/* For compression */
>  	unsigned char compress_algorithm;	/* algorithm type */
> -	unsigned compress_log_size;		/* cluster log size */
> +	unsigned char compress_log_size;	/* cluster log size */
> +	bool compress_chksum;			/* compressed data chksum */
>  	unsigned char compress_ext_cnt;		/* extension count */
>  	unsigned char extensions[COMPRESS_EXT_NUM][F2FS_EXTENSION_LEN];	/* extensions */
>  };
> @@ -731,6 +732,7 @@ struct f2fs_inode_info {
>  	atomic_t i_compr_blocks;		/* # of compressed blocks */
>  	unsigned char i_compress_algorithm;	/* algorithm type */
>  	unsigned char i_log_cluster_size;	/* log of cluster size */
> +	unsigned short i_compress_flag;		/* compress flag */
>  	unsigned int i_cluster_size;		/* cluster size */
>  };
>  
> @@ -1270,9 +1272,15 @@ enum compress_algorithm_type {
>  	COMPRESS_MAX,
>  };
>  
> +enum compress_flag {
> +	COMPRESS_CHKSUM,
> +	COMPRESS_MAX_FLAG,
> +};
> +
>  #define COMPRESS_DATA_RESERVED_SIZE		5
>  struct compress_data {
>  	__le32 clen;			/* compressed data size */
> +	__le32 chksum;			/* compressed data chksum */
>  	__le32 reserved[COMPRESS_DATA_RESERVED_SIZE];	/* reserved */
>  	u8 cdata[];			/* compressed data */
>  };
> @@ -3882,6 +3890,9 @@ static inline void set_compress_context(struct inode *inode)
>  			F2FS_OPTION(sbi).compress_algorithm;
>  	F2FS_I(inode)->i_log_cluster_size =
>  			F2FS_OPTION(sbi).compress_log_size;
> +	F2FS_I(inode)->i_compress_flag =
> +			F2FS_OPTION(sbi).compress_chksum ?
> +				1 << COMPRESS_CHKSUM : 0;
>  	F2FS_I(inode)->i_cluster_size =
>  			1 << F2FS_I(inode)->i_log_cluster_size;
>  	F2FS_I(inode)->i_flags |= F2FS_COMPR_FL;
> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> index 657db2fb6739..de8f7fc89efa 100644
> --- a/fs/f2fs/inode.c
> +++ b/fs/f2fs/inode.c
> @@ -456,6 +456,7 @@ static int do_read_inode(struct inode *inode)
>  					le64_to_cpu(ri->i_compr_blocks));
>  			fi->i_compress_algorithm = ri->i_compress_algorithm;
>  			fi->i_log_cluster_size = ri->i_log_cluster_size;
> +			fi->i_compress_flag = ri->i_compress_flag;
>  			fi->i_cluster_size = 1 << fi->i_log_cluster_size;
>  			set_inode_flag(inode, FI_COMPRESSED_FILE);
>  		}
> @@ -634,6 +635,8 @@ void f2fs_update_inode(struct inode *inode, struct page *node_page)
>  					&F2FS_I(inode)->i_compr_blocks));
>  			ri->i_compress_algorithm =
>  				F2FS_I(inode)->i_compress_algorithm;
> +			ri->i_compress_flag =
> +				cpu_to_le16(F2FS_I(inode)->i_compress_flag);
>  			ri->i_log_cluster_size =
>  				F2FS_I(inode)->i_log_cluster_size;
>  		}
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 00eff2f51807..f8de4d83a5be 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -146,6 +146,7 @@ enum {
>  	Opt_compress_algorithm,
>  	Opt_compress_log_size,
>  	Opt_compress_extension,
> +	Opt_compress_chksum,
>  	Opt_atgc,
>  	Opt_err,
>  };
> @@ -214,6 +215,7 @@ static match_table_t f2fs_tokens = {
>  	{Opt_compress_algorithm, "compress_algorithm=%s"},
>  	{Opt_compress_log_size, "compress_log_size=%u"},
>  	{Opt_compress_extension, "compress_extension=%s"},
> +	{Opt_compress_chksum, "compress_chksum"},
>  	{Opt_atgc, "atgc"},
>  	{Opt_err, NULL},
>  };
> @@ -934,10 +936,14 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
>  			F2FS_OPTION(sbi).compress_ext_cnt++;
>  			kfree(name);
>  			break;
> +		case Opt_compress_chksum:
> +			F2FS_OPTION(sbi).compress_chksum = true;
> +			break;
>  #else
>  		case Opt_compress_algorithm:
>  		case Opt_compress_log_size:
>  		case Opt_compress_extension:
> +		case Opt_compress_chksum:
>  			f2fs_info(sbi, "compression options not supported");
>  			break;
>  #endif
> @@ -1523,6 +1529,9 @@ static inline void f2fs_show_compress_options(struct seq_file *seq,
>  		seq_printf(seq, ",compress_extension=%s",
>  			F2FS_OPTION(sbi).extensions[i]);
>  	}
> +
> +	if (F2FS_OPTION(sbi).compress_chksum)
> +		seq_puts(seq, ",compress_chksum");
>  }
>  
>  static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> index a5dbb57a687f..7dc2a06cf19a 100644
> --- a/include/linux/f2fs_fs.h
> +++ b/include/linux/f2fs_fs.h
> @@ -273,7 +273,7 @@ struct f2fs_inode {
>  			__le64 i_compr_blocks;	/* # of compressed blocks */
>  			__u8 i_compress_algorithm;	/* compress algorithm */
>  			__u8 i_log_cluster_size;	/* log of cluster size */
> -			__le16 i_padding;		/* padding */
> +			__le16 i_compress_flag;		/* compress flag */
>  			__le32 i_extra_end[0];	/* for attribute size calculation */
>  		} __packed;
>  		__le32 i_addr[DEF_ADDRS_PER_INODE];	/* Pointers to data blocks */
> -- 
> 2.26.2