Re: [PATCH 4/6] f2fs: introduce cp_lock to protect updating of ckpt_flags

From: Jaegeuk Kim
Date: Mon Sep 19 2016 - 17:49:11 EST

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In reply to: Chao Yu: "[PATCH 4/6] f2fs: introduce cp_lock to protect updating of ckpt_flags"
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Hi Chao,

On Sun, Sep 18, 2016 at 11:30:06PM +0800, Chao Yu wrote:
> From: Chao Yu <yuchao0@xxxxxxxxxx>
>
> 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 <yuchao0@xxxxxxxxxx>
> ---
> 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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In reply to: Chao Yu: "[PATCH 4/6] f2fs: introduce cp_lock to protect updating of ckpt_flags"
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