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 <c...@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


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