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

Chao Yu
2022-09-20T15:43:57Z

On 2022/9/20 8:56, Jaegeuk Kim wrote:
> 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?

Good idea, maybe:
Bit Value max number of type
[0] need fsck flag 1
[1-5] reason to stop checkpoint 32
[6-13] reason to fsck 256

Thanks

>
>> + }
>> }
>>
>> /*
>> 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