Re: [RFC PATCH v2] f2fs: record need_fsck in super_block

Jaegeuk Kim
2022-09-20T00:56:54Z

On 09/13, Chao Yu wrote:
> Once CP_ERROR_FLAG is set, checkpoint is disallowed to be triggered to
> persist CP_FSCK_FLAG, fsck won't repair the image due to lack of
> CP_FSCK_FLAG.
>
> This patch proposes to persist newly introduced SB_NEED_FSCK flag into
> super block if CP_ERROR_FLAG and SBI_NEED_FSCK is set, later, once fsck
> detect this flag, it can check and repair corrupted image in time.
>
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
> v2:
> - remove unneeded codes.
> fs/f2fs/checkpoint.c | 6 +++++-
> fs/f2fs/f2fs.h | 1 +
> fs/f2fs/super.c | 26 ++++++++++++++++++++++++++
> include/linux/f2fs_fs.h | 5 ++++-
> 4 files changed, 36 insertions(+), 2 deletions(-)
>
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index c3119e4c890c..0836fce40394 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -30,8 +30,12 @@ void f2fs_stop_checkpoint(struct f2fs_sb_info *sbi, bool end_io)
> {
> f2fs_build_fault_attr(sbi, 0, 0);
> set_ckpt_flags(sbi, CP_ERROR_FLAG);
> - if (!end_io)
> + if (!end_io) {
> f2fs_flush_merged_writes(sbi);
> +
> + if (is_sbi_flag_set(sbi, SBI_NEED_FSCK))
> + f2fs_update_sb_flags(sbi, SB_NEED_FSCK);

Let's think of putting some more context in superblock, if we want to overwrite
it. E.g., a reason to stop checkpoint?

> + }
> }
>
> /*
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index dee7b67a17a6..1960a98c7555 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -3556,6 +3556,7 @@ int f2fs_enable_quota_files(struct f2fs_sb_info *sbi, bool rdonly);
> int f2fs_quota_sync(struct super_block *sb, int type);
> loff_t max_file_blocks(struct inode *inode);
> void f2fs_quota_off_umount(struct super_block *sb);
> +void f2fs_update_sb_flags(struct f2fs_sb_info *sbi, unsigned int flag);
> int f2fs_commit_super(struct f2fs_sb_info *sbi, bool recover);
> int f2fs_sync_fs(struct super_block *sb, int sync);
> int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi);
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index b8e5fe244596..c99ba840593d 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -3846,6 +3846,32 @@ int f2fs_commit_super(struct f2fs_sb_info *sbi, bool recover)
> return err;
> }
>
> +void f2fs_update_sb_flags(struct f2fs_sb_info *sbi, unsigned int flag)
> +{
> + unsigned short s_flags;
> + int err;
> +
> + if (le16_to_cpu(F2FS_RAW_SUPER(sbi)->s_flags) & SB_NEED_FSCK)
> + return;
> +
> + f2fs_down_write(&sbi->sb_lock);
> +
> + s_flags = le16_to_cpu(F2FS_RAW_SUPER(sbi)->s_flags);
> +
> + if (s_flags & SB_NEED_FSCK)
> + goto out_unlock;
> +
> + F2FS_RAW_SUPER(sbi)->s_flags = cpu_to_le16(s_flags | SB_NEED_FSCK);
> +
> + err = f2fs_commit_super(sbi, false);
> + if (err) {
> + f2fs_warn(sbi, "f2fs_commit_super fails to persist flag: %u, err:%d", flag, err);
> + F2FS_RAW_SUPER(sbi)->s_flags = s_flags;
> + }
> +out_unlock:
> + f2fs_up_write(&sbi->sb_lock);
> +}
> +
> static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
> {
> struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> index d445150c5350..124176e2a42c 100644
> --- a/include/linux/f2fs_fs.h
> +++ b/include/linux/f2fs_fs.h
> @@ -73,6 +73,8 @@ struct f2fs_device {
> __le32 total_segments;
> } __packed;
>
> +#define SB_NEED_FSCK 0x00000001 /* need fsck */
> +
> struct f2fs_super_block {
> __le32 magic; /* Magic Number */
> __le16 major_ver; /* Major Version */
> @@ -116,7 +118,8 @@ struct f2fs_super_block {
> __u8 hot_ext_count; /* # of hot file extension */
> __le16 s_encoding; /* Filename charset encoding */
> __le16 s_encoding_flags; /* Filename charset encoding flags */
> - __u8 reserved[306]; /* valid reserved region */
> + __le16 s_flags; /* super block flags */
> + __u8 reserved[304]; /* valid reserved region */
> __le32 crc; /* checksum of superblock */
> } __packed;
>
> --
> 2.25.1