Hi Chao,

On Sun, Sep 18, 2016 at 11:30:06PM +0800, Chao Yu wrote:
> From: Chao Yu <yuch...@huawei.com>
> 
> This patch introduces spinlock to protect updating process of ckpt_flags
> field in struct f2fs_checkpoint, it avoids incorrectly updating in race
> condition.

So, I'm seeing a race condition between f2fs_stop_checkpoint(),
write_checkpoint(), and f2fs_fill_super().

How about just adding f2fs_lock_op() in f2fs_stop_checkpoint()?

Thanks,

> Signed-off-by: Chao Yu <yuch...@huawei.com>
> ---
>  fs/f2fs/checkpoint.c | 24 ++++++++++++------------
>  fs/f2fs/f2fs.h       | 29 +++++++++++++++++++++--------
>  fs/f2fs/recovery.c   |  2 +-
>  fs/f2fs/segment.c    |  4 ++--
>  fs/f2fs/super.c      |  5 +++--
>  5 files changed, 39 insertions(+), 25 deletions(-)
> 
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index df56a43..0338f8c 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -28,7 +28,7 @@ struct kmem_cache *inode_entry_slab;
>  
>  void f2fs_stop_checkpoint(struct f2fs_sb_info *sbi, bool end_io)
>  {
> -     set_ckpt_flags(sbi->ckpt, CP_ERROR_FLAG);
> +     set_ckpt_flags(sbi, CP_ERROR_FLAG);
>       sbi->sb->s_flags |= MS_RDONLY;
>       if (!end_io)
>               f2fs_flush_merged_bios(sbi);
> @@ -571,7 +571,7 @@ int recover_orphan_inodes(struct f2fs_sb_info *sbi)
>       block_t start_blk, orphan_blocks, i, j;
>       int err;
>  
> -     if (!is_set_ckpt_flags(F2FS_CKPT(sbi), CP_ORPHAN_PRESENT_FLAG))
> +     if (!is_set_ckpt_flags(sbi, CP_ORPHAN_PRESENT_FLAG))
>               return 0;
>  
>       start_blk = __start_cp_addr(sbi) + 1 + __cp_payload(sbi);
> @@ -595,7 +595,7 @@ int recover_orphan_inodes(struct f2fs_sb_info *sbi)
>               f2fs_put_page(page, 1);
>       }
>       /* clear Orphan Flag */
> -     clear_ckpt_flags(F2FS_CKPT(sbi), CP_ORPHAN_PRESENT_FLAG);
> +     clear_ckpt_flags(sbi, CP_ORPHAN_PRESENT_FLAG);
>       return 0;
>  }
>  
> @@ -1054,9 +1054,9 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, 
> struct cp_control *cpc)
>       /* 2 cp  + n data seg summary + orphan inode blocks */
>       data_sum_blocks = npages_for_summary_flush(sbi, false);
>       if (data_sum_blocks < NR_CURSEG_DATA_TYPE)
> -             set_ckpt_flags(ckpt, CP_COMPACT_SUM_FLAG);
> +             set_ckpt_flags(sbi, CP_COMPACT_SUM_FLAG);
>       else
> -             clear_ckpt_flags(ckpt, CP_COMPACT_SUM_FLAG);
> +             clear_ckpt_flags(sbi, CP_COMPACT_SUM_FLAG);
>  
>       orphan_blocks = GET_ORPHAN_BLOCKS(orphan_num);
>       ckpt->cp_pack_start_sum = cpu_to_le32(1 + cp_payload_blks +
> @@ -1072,22 +1072,22 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, 
> struct cp_control *cpc)
>                               orphan_blocks);
>  
>       if (cpc->reason == CP_UMOUNT)
> -             set_ckpt_flags(ckpt, CP_UMOUNT_FLAG);
> +             set_ckpt_flags(sbi, CP_UMOUNT_FLAG);
>       else
> -             clear_ckpt_flags(ckpt, CP_UMOUNT_FLAG);
> +             clear_ckpt_flags(sbi, CP_UMOUNT_FLAG);
>  
>       if (cpc->reason == CP_FASTBOOT)
> -             set_ckpt_flags(ckpt, CP_FASTBOOT_FLAG);
> +             set_ckpt_flags(sbi, CP_FASTBOOT_FLAG);
>       else
> -             clear_ckpt_flags(ckpt, CP_FASTBOOT_FLAG);
> +             clear_ckpt_flags(sbi, CP_FASTBOOT_FLAG);
>  
>       if (orphan_num)
> -             set_ckpt_flags(ckpt, CP_ORPHAN_PRESENT_FLAG);
> +             set_ckpt_flags(sbi, CP_ORPHAN_PRESENT_FLAG);
>       else
> -             clear_ckpt_flags(ckpt, CP_ORPHAN_PRESENT_FLAG);
> +             clear_ckpt_flags(sbi, CP_ORPHAN_PRESENT_FLAG);
>  
>       if (is_sbi_flag_set(sbi, SBI_NEED_FSCK))
> -             set_ckpt_flags(ckpt, CP_FSCK_FLAG);
> +             set_ckpt_flags(sbi, CP_FSCK_FLAG);
>  
>       /* update SIT/NAT bitmap */
>       get_sit_bitmap(sbi, __bitmap_ptr(sbi, SIT_BITMAP));
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index c30f744b..b615f3f 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -814,6 +814,7 @@ struct f2fs_sb_info {
>  
>       /* for checkpoint */
>       struct f2fs_checkpoint *ckpt;           /* raw checkpoint pointer */
> +     spinlock_t cp_lock;                     /* for flag in ckpt */
>       struct inode *meta_inode;               /* cache meta blocks */
>       struct mutex cp_mutex;                  /* checkpoint procedure lock */
>       struct rw_semaphore cp_rwsem;           /* blocking FS operations */
> @@ -1083,24 +1084,36 @@ static inline unsigned long long 
> cur_cp_version(struct f2fs_checkpoint *cp)
>       return le64_to_cpu(cp->checkpoint_ver);
>  }
>  
> -static inline bool is_set_ckpt_flags(struct f2fs_checkpoint *cp, unsigned 
> int f)
> +static inline bool is_set_ckpt_flags(struct f2fs_sb_info *sbi, unsigned int 
> f)
>  {
> +     struct f2fs_checkpoint *cp = F2FS_CKPT(sbi);
>       unsigned int ckpt_flags = le32_to_cpu(cp->ckpt_flags);
> +
>       return ckpt_flags & f;
>  }
>  
> -static inline void set_ckpt_flags(struct f2fs_checkpoint *cp, unsigned int f)
> +static inline void set_ckpt_flags(struct f2fs_sb_info *sbi, unsigned int f)
>  {
> -     unsigned int ckpt_flags = le32_to_cpu(cp->ckpt_flags);
> +     struct f2fs_checkpoint *cp = F2FS_CKPT(sbi);
> +     unsigned int ckpt_flags;
> +
> +     spin_lock(&sbi->cp_lock);
> +     ckpt_flags = le32_to_cpu(cp->ckpt_flags);
>       ckpt_flags |= f;
>       cp->ckpt_flags = cpu_to_le32(ckpt_flags);
> +     spin_unlock(&sbi->cp_lock);
>  }
>  
> -static inline void clear_ckpt_flags(struct f2fs_checkpoint *cp, unsigned int 
> f)
> +static inline void clear_ckpt_flags(struct f2fs_sb_info *sbi, unsigned int f)
>  {
> -     unsigned int ckpt_flags = le32_to_cpu(cp->ckpt_flags);
> +     struct f2fs_checkpoint *cp = F2FS_CKPT(sbi);
> +     unsigned int ckpt_flags;
> +
> +     spin_lock(&sbi->cp_lock);
> +     ckpt_flags = le32_to_cpu(cp->ckpt_flags);
>       ckpt_flags &= (~f);
>       cp->ckpt_flags = cpu_to_le32(ckpt_flags);
> +     spin_unlock(&sbi->cp_lock);
>  }
>  
>  static inline bool f2fs_discard_en(struct f2fs_sb_info *sbi)
> @@ -1148,8 +1161,8 @@ static inline bool __remain_node_summaries(int reason)
>  
>  static inline bool __exist_node_summaries(struct f2fs_sb_info *sbi)
>  {
> -     return (is_set_ckpt_flags(F2FS_CKPT(sbi), CP_UMOUNT_FLAG) ||
> -                     is_set_ckpt_flags(F2FS_CKPT(sbi), CP_FASTBOOT_FLAG));
> +     return (is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG) ||
> +                     is_set_ckpt_flags(sbi, CP_FASTBOOT_FLAG));
>  }
>  
>  /*
> @@ -1851,7 +1864,7 @@ static inline int f2fs_readonly(struct super_block *sb)
>  
>  static inline bool f2fs_cp_error(struct f2fs_sb_info *sbi)
>  {
> -     return is_set_ckpt_flags(sbi->ckpt, CP_ERROR_FLAG);
> +     return is_set_ckpt_flags(sbi, CP_ERROR_FLAG);
>  }
>  
>  static inline bool is_dot_dotdot(const struct qstr *str)
> diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
> index ad748e5..37d99d2 100644
> --- a/fs/f2fs/recovery.c
> +++ b/fs/f2fs/recovery.c
> @@ -649,7 +649,7 @@ out:
>                       invalidate_mapping_pages(META_MAPPING(sbi),
>                                                       blkaddr, blkaddr);
>  
> -             set_ckpt_flags(sbi->ckpt, CP_ERROR_FLAG);
> +             set_ckpt_flags(sbi, CP_ERROR_FLAG);
>               mutex_unlock(&sbi->cp_mutex);
>       } else if (need_writecp) {
>               struct cp_control cpc = {
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 101b58f..dc68f30 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1825,7 +1825,7 @@ static int restore_curseg_summaries(struct f2fs_sb_info 
> *sbi)
>       int type = CURSEG_HOT_DATA;
>       int err;
>  
> -     if (is_set_ckpt_flags(F2FS_CKPT(sbi), CP_COMPACT_SUM_FLAG)) {
> +     if (is_set_ckpt_flags(sbi, CP_COMPACT_SUM_FLAG)) {
>               int npages = npages_for_summary_flush(sbi, true);
>  
>               if (npages >= 2)
> @@ -1922,7 +1922,7 @@ static void write_normal_summaries(struct f2fs_sb_info 
> *sbi,
>  
>  void write_data_summaries(struct f2fs_sb_info *sbi, block_t start_blk)
>  {
> -     if (is_set_ckpt_flags(F2FS_CKPT(sbi), CP_COMPACT_SUM_FLAG))
> +     if (is_set_ckpt_flags(sbi, CP_COMPACT_SUM_FLAG))
>               write_compacted_summaries(sbi, start_blk);
>       else
>               write_normal_summaries(sbi, start_blk, CURSEG_HOT_DATA);
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 555217f..f809729 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -735,7 +735,7 @@ static void f2fs_put_super(struct super_block *sb)
>        * clean checkpoint again.
>        */
>       if (is_sbi_flag_set(sbi, SBI_IS_DIRTY) ||
> -                     !is_set_ckpt_flags(F2FS_CKPT(sbi), CP_UMOUNT_FLAG)) {
> +                     !is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) {
>               struct cp_control cpc = {
>                       .reason = CP_UMOUNT,
>               };
> @@ -1477,6 +1477,7 @@ static void init_sb_info(struct f2fs_sb_info *sbi)
>       mutex_init(&sbi->umount_mutex);
>       mutex_init(&sbi->wio_mutex[NODE]);
>       mutex_init(&sbi->wio_mutex[DATA]);
> +     spin_lock_init(&sbi->cp_lock);
>  
>  #ifdef CONFIG_F2FS_FS_ENCRYPTION
>       memcpy(sbi->key_prefix, F2FS_KEY_DESC_PREFIX,
> @@ -1818,7 +1819,7 @@ try_onemore:
>                * previous checkpoint was not done by clean system shutdown.
>                */
>               if (bdev_read_only(sb->s_bdev) &&
> -                             !is_set_ckpt_flags(sbi->ckpt, CP_UMOUNT_FLAG)) {
> +                             !is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) {
>                       err = -EROFS;
>                       goto free_kobj;
>               }
> -- 
> 2.7.2

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