On 2018/8/8 18:27, Junling Zheng wrote:
> Now we support crc32 checksum for superblock.
> 
> Signed-off-by: Junling Zheng <zhengjunl...@huawei.com>
> ---
> v2 -> v3:
>  - add sysfs entry for superblock checksum.
>  - move the crc checking to the beginning of sanity_check_raw_super().
>  - fix the NULL pointer dereference as sb->s_fs_info hasn't be set yet in
>    sanity_check_raw_super().
> v1 -> v2:
>  - fix to switch endian of crc.
>  fs/f2fs/f2fs.h          |  2 ++
>  fs/f2fs/super.c         | 29 +++++++++++++++++++++++++++++
>  fs/f2fs/sysfs.c         |  7 +++++++
>  include/linux/f2fs_fs.h |  3 ++-
>  4 files changed, 40 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 4525f4f82af0..d50d6efda96b 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -147,6 +147,7 @@ struct f2fs_mount_info {
>  #define F2FS_FEATURE_INODE_CRTIME    0x0100
>  #define F2FS_FEATURE_LOST_FOUND              0x0200
>  #define F2FS_FEATURE_VERITY          0x0400  /* reserved */
> +#define F2FS_FEATURE_SB_CHKSUM               0x0800
>  
>  #define F2FS_HAS_FEATURE(sb, mask)                                   \
>       ((F2FS_SB(sb)->raw_super->feature & cpu_to_le32(mask)) != 0)
> @@ -3376,6 +3377,7 @@ F2FS_FEATURE_FUNCS(flexible_inline_xattr, 
> FLEXIBLE_INLINE_XATTR);
>  F2FS_FEATURE_FUNCS(quota_ino, QUOTA_INO);
>  F2FS_FEATURE_FUNCS(inode_crtime, INODE_CRTIME);
>  F2FS_FEATURE_FUNCS(lost_found, LOST_FOUND);
> +F2FS_FEATURE_FUNCS(sb_chksum, SB_CHKSUM);
>  
>  #ifdef CONFIG_BLK_DEV_ZONED
>  static inline int get_blkz_type(struct f2fs_sb_info *sbi,
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index bd57be470e23..c3dbafa31613 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -2149,6 +2149,26 @@ static int sanity_check_raw_super(struct f2fs_sb_info 
> *sbi,
>                                       (bh->b_data + F2FS_SUPER_OFFSET);
>       struct super_block *sb = sbi->sb;
>       unsigned int blocksize;
> +     size_t crc_offset = 0;
> +     __u32 crc = 0;
> +
> +     /* Check checksum_offset and crc in superblock */
> +     if (le32_to_cpu(raw_super->feature) & F2FS_FEATURE_SB_CHKSUM) {
> +             crc_offset = le32_to_cpu(raw_super->checksum_offset);
> +             if (crc_offset !=
> +                     offsetof(struct f2fs_super_block, crc)) {
> +                     f2fs_msg(sb, KERN_INFO,
> +                             "Invalid SB checksum offset: %lu",

warning: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument
4 has type ‘size_t’ [-Wformat=]
     crc_offset);

Otherwise, it looks good to me, you can add in next version:

Reviewed-by: Chao Yu <yuch...@huawei.com>

Thanks,

> +                             crc_offset);
> +                     return 1;
> +             }
> +             crc = le32_to_cpu(raw_super->crc);
> +             if (!f2fs_crc_valid(sbi, crc, raw_super, crc_offset)) {
> +                     f2fs_msg(sb, KERN_INFO,
> +                             "Invalid SB checksum value: %u", crc);
> +                     return 1;
> +             }
> +     }
>  
>       if (F2FS_SUPER_MAGIC != le32_to_cpu(raw_super->magic)) {
>               f2fs_msg(sb, KERN_INFO,
> @@ -2568,6 +2588,7 @@ static int read_raw_super_block(struct f2fs_sb_info 
> *sbi,
>  int f2fs_commit_super(struct f2fs_sb_info *sbi, bool recover)
>  {
>       struct buffer_head *bh;
> +     __u32 crc = 0;
>       int err;
>  
>       if ((recover && f2fs_readonly(sbi->sb)) ||
> @@ -2576,6 +2597,14 @@ int f2fs_commit_super(struct f2fs_sb_info *sbi, bool 
> recover)
>               return -EROFS;
>       }
>  
> +     /* we should update superblock crc here */
> +     if (!recover &&
> +             F2FS_HAS_FEATURE(sbi->sb, F2FS_FEATURE_SB_CHKSUM)) {
> +             crc = f2fs_crc32(sbi, F2FS_RAW_SUPER(sbi),
> +                             offsetof(struct f2fs_super_block, crc));
> +             F2FS_RAW_SUPER(sbi)->crc = cpu_to_le32(crc);
> +     }
> +
>       /* write back-up superblock first */
>       bh = sb_bread(sbi->sb, sbi->valid_super_block ? 0 : 1);
>       if (!bh)
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index cd2e030e47b8..c86d91be6c48 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -120,6 +120,9 @@ static ssize_t features_show(struct f2fs_attr *a,
>       if (f2fs_sb_has_lost_found(sb))
>               len += snprintf(buf + len, PAGE_SIZE - len, "%s%s",
>                               len ? ", " : "", "lost_found");
> +     if (f2fs_sb_has_sb_chksum(sb))
> +             len += snprintf(buf + len, PAGE_SIZE - len, "%s%s",
> +                             len ? ", " : "", "sb_checksum");
>       len += snprintf(buf + len, PAGE_SIZE - len, "\n");
>       return len;
>  }
> @@ -337,6 +340,7 @@ enum feat_id {
>       FEAT_QUOTA_INO,
>       FEAT_INODE_CRTIME,
>       FEAT_LOST_FOUND,
> +     FEAT_SB_CHECKSUM,
>  };
>  
>  static ssize_t f2fs_feature_show(struct f2fs_attr *a,
> @@ -353,6 +357,7 @@ static ssize_t f2fs_feature_show(struct f2fs_attr *a,
>       case FEAT_QUOTA_INO:
>       case FEAT_INODE_CRTIME:
>       case FEAT_LOST_FOUND:
> +     case FEAT_SB_CHECKSUM:
>               return snprintf(buf, PAGE_SIZE, "supported\n");
>       }
>       return 0;
> @@ -433,6 +438,7 @@ F2FS_FEATURE_RO_ATTR(flexible_inline_xattr, 
> FEAT_FLEXIBLE_INLINE_XATTR);
>  F2FS_FEATURE_RO_ATTR(quota_ino, FEAT_QUOTA_INO);
>  F2FS_FEATURE_RO_ATTR(inode_crtime, FEAT_INODE_CRTIME);
>  F2FS_FEATURE_RO_ATTR(lost_found, FEAT_LOST_FOUND);
> +F2FS_FEATURE_RO_ATTR(sb_checksum, FEAT_SB_CHECKSUM);
>  
>  #define ATTR_LIST(name) (&f2fs_attr_##name.attr)
>  static struct attribute *f2fs_attrs[] = {
> @@ -489,6 +495,7 @@ static struct attribute *f2fs_feat_attrs[] = {
>       ATTR_LIST(quota_ino),
>       ATTR_LIST(inode_crtime),
>       ATTR_LIST(lost_found),
> +     ATTR_LIST(sb_checksum),
>       NULL,
>  };
>  
> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> index f70f8ac9c4f4..aa4b586569c1 100644
> --- a/include/linux/f2fs_fs.h
> +++ b/include/linux/f2fs_fs.h
> @@ -112,7 +112,8 @@ struct f2fs_super_block {
>       struct f2fs_device devs[MAX_DEVICES];   /* device list */
>       __le32 qf_ino[F2FS_MAX_QUOTAS]; /* quota inode numbers */
>       __u8 hot_ext_count;             /* # of hot file extension */
> -     __u8 reserved[314];             /* valid reserved region */
> +     __u8 reserved[310];             /* valid reserved region */
> +     __le32 crc;                     /* checksum of superblock */
>  } __packed;
>  
>  /*
> 

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