f2fs: fix to avoid atomicity corruption of atomic file

In the case of the following call stack for an atomic file,
FI_DIRTY_INODE is set, but FI_ATOMIC_DIRTIED is not subsequently set.

f2fs_file_write_iter
  f2fs_map_blocks
    f2fs_reserve_new_blocks
      inc_valid_block_count
        __mark_inode_dirty(dquot)
          f2fs_dirty_inode

If FI_ATOMIC_DIRTIED is not set, atomic file can encounter corruption
due to a mismatch between old file size and new data.

To resolve this issue, I changed to set FI_ATOMIC_DIRTIED when
FI_DIRTY_INODE is set. This ensures that FI_DIRTY_INODE, which was
previously cleared by the Writeback thread during the commit atomic, is
set and i_size is updated.

Cc: <stable@vger.kernel.org>
Fixes: fccaa81d ("f2fs: prevent atomic file from being dirtied before commit")
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Reviewed-by: Sunmin Jeong <s_min.jeong@samsung.com>
Signed-off-by: Yeongjin Gil <youngjin.gil@samsung.com>
Reviewed-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>