Re: [f2fs-dev] [PATCH] f2fs: write the directory inode in fsync before checkpoint

[Daeho Jeong]

On Fri, Oct 9, 2026 at 2:03 AM Chao Yu <chao@xxxxxxxxxx> wrote:
>
> On 10/8/26 06:36, Daeho Jeong wrote:
> > From: Daeho Jeong <daehojeong@xxxxxxxxxx>
> >
> > fsync() on a directory is done by a checkpoint, but the checkpoint
> > does not write timestamp-only inode updates. Since commit 7c45729a4d6d
> > ("f2fs: keep dirty inodes selectively for checkpoint"), such updates
> > are marked with sync=false and left to inode writeback on purpose.
> >
> > fsync() on a regular file calls f2fs_write_inode() first when the
> > inode is dirty, but fsync() on a directory goes to the checkpoint
> > directly and misses it. So if the last change to a directory only
> > updated its timestamps, e.g. unlinking a file in it, the new mtime is
> > lost after a sudden power off even though fsync() returned. generic/547
> > fails sometimes because of this.
>
> Has 9ec09d5f4b31 ("f2fs: dirty directory inodes on mtime/ctime update") fixed
> this issue?
>
> Thanks,

Oh, yes, it does. I missed that commit since I tested on a tree
without it. Please drop this patch.

Thanks,

Thanks,

>
> >
> > Call f2fs_write_inode() for a directory before the checkpoint, as the
> > regular file path does. The inode block becomes dirty and is written by
> > the same checkpoint, so no extra checkpoint or flush is added.
> > Timestamp-only updates without fsync() are still not written by the
> > checkpoint.
> >
> > Fixes: 7c45729a4d6d ("f2fs: keep dirty inodes selectively for checkpoint")
> > Signed-off-by: Daeho Jeong <daehojeong@xxxxxxxxxx>
> > ---
> >  fs/f2fs/file.c | 9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 56c686b8580..b012cc22307 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -351,8 +351,15 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
> >
> >       trace_f2fs_sync_file_enter(inode);
> >
> > -     if (S_ISDIR(inode->i_mode))
> > +     if (S_ISDIR(inode->i_mode)) {
> > +             /*
> > +              * Checkpoint writes only the inodes on the dirty meta list.
> > +              * Timestamp updates of a directory, e.g. by unlinking a file
> > +              * in it, do not put it on the list, so write it here.
> > +              */
> > +             f2fs_write_inode(inode, NULL);
> >               goto go_write;
> > +     }
> >
> >       /* if fdatasync is triggered, let's do in-place-update */
> >       if (datasync || get_dirty_pages(inode) <= SM_I(sbi)->min_fsync_blocks)
>