Re: [PATCH] f2fs: compress: support chksum

From: Jaegeuk Kim
Date: Mon Nov 02 2020 - 11:31:28 EST

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@xxxxxxxxxx>
> ---
> 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