On 2018/7/27 4:54, Weichao Guo wrote:
> We may encounter both checkpoints invalid in such a case:
> 1. write checkpoint A, B, C;
> 2. sudden power-cut during write checkpoint D;
> 3. fsck changes the total block count of checkpoint C;
> 4. sudden power-cut during fsck write checkpoint C in place
>
> --------- ---------
> | ver C | | ver D |
> | ... | | ... |
> | content | | content |
> | ... | | ... |
> | ver C | | |
> | ver A | | ver B |
> --------- ---------
>
> As the total # of checkpoint C is changed, an old cp block
> like ver A or an invalid cp block may be referenced.
> To avoid both checkpoints invalid, and considering fsck should
> not update the checkpoint version, fsck could write checkpoint
> out of place first and then write checkpoint in place. This
> makes sure the file system is fixed by fsck and at least one
> of the two checkpoints is valid.
>
> Signed-off-by: Weichao Guo <[email protected]>
> ---
> fsck/defrag.c | 2 +-
> fsck/fsck.c | 14 +++++++++++++-
> fsck/fsck.h | 1 +
> fsck/mount.c | 16 ++++++++++++++--
> fsck/sload.c | 2 +-
> 5 files changed, 30 insertions(+), 5 deletions(-)
>
> diff --git a/fsck/defrag.c b/fsck/defrag.c
> index bea0293..9fc932f 100644
> --- a/fsck/defrag.c
> +++ b/fsck/defrag.c
> @@ -96,7 +96,7 @@ int f2fs_defragment(struct f2fs_sb_info *sbi, u64 from, u64
> len, u64 to, int lef
> /* flush dirty sit entries */
> flush_sit_entries(sbi);
>
> - write_checkpoint(sbi);
> + __write_checkpoint(sbi);
>
> return 0;
> }
> diff --git a/fsck/fsck.c b/fsck/fsck.c
> index 91c8529..f2ff4bc 100644
> --- a/fsck/fsck.c
> +++ b/fsck/fsck.c
> @@ -1943,7 +1943,7 @@ static void flush_curseg_sit_entries(struct
> f2fs_sb_info *sbi)
> free(sit_blk);
> }
>
> -static void fix_checkpoint(struct f2fs_sb_info *sbi)
> +static void __fix_checkpoint(struct f2fs_sb_info *sbi)
> {
> struct f2fs_fsck *fsck = F2FS_FSCK(sbi);
> struct f2fs_super_block *sb = F2FS_RAW_SUPER(sbi);
> @@ -2004,6 +2004,18 @@ static void fix_checkpoint(struct f2fs_sb_info *sbi)
> write_nat_bits(sbi, sb, cp, sbi->cur_cp);
> }
>
> +static void fix_checkpoint(struct f2fs_sb_info *sbi)
> +{
> + int i = 0;
> +
> + for (i = 0; i < 2; i++) {
> + /* write checkpoint out of place first */
> + sbi->cur_cp = sbi->cur_cp % 2 + 1;
> + __fix_checkpoint(sbi);
> + f2fs_fsync_device();
It needs to check return value here.
We can add below codes in the end of __fix_checkpoint()?
ret = f2fs_fsync_device();
ASSERT(ret >= 0);
> + }
> +}
> +
> int check_curseg_offset(struct f2fs_sb_info *sbi)
> {
> int i;
> diff --git a/fsck/fsck.h b/fsck/fsck.h
> index 8e133fa..068dd34 100644
> --- a/fsck/fsck.h
> +++ b/fsck/fsck.h
> @@ -175,6 +175,7 @@ extern void flush_sit_entries(struct f2fs_sb_info *);
> extern void move_curseg_info(struct f2fs_sb_info *, u64);
> extern void write_curseg_info(struct f2fs_sb_info *);
> extern int find_next_free_block(struct f2fs_sb_info *, u64 *, int, int);
> +extern void __write_checkpoint(struct f2fs_sb_info *);
> extern void write_checkpoint(struct f2fs_sb_info *);
> extern void update_data_blkaddr(struct f2fs_sb_info *, nid_t, u16, block_t);
> extern void update_nat_blkaddr(struct f2fs_sb_info *, nid_t, nid_t, block_t);
> diff --git a/fsck/mount.c b/fsck/mount.c
> index e5574c5..8a29421 100644
> --- a/fsck/mount.c
> +++ b/fsck/mount.c
> @@ -1856,7 +1856,7 @@ void flush_journal_entries(struct f2fs_sb_info *sbi)
> int n_sits = flush_sit_journal_entries(sbi);
>
> if (n_nats || n_sits)
> - write_checkpoint(sbi);
> + __write_checkpoint(sbi);
> }
>
> void flush_sit_entries(struct f2fs_sb_info *sbi)
> @@ -2079,7 +2079,7 @@ void nullify_nat_entry(struct f2fs_sb_info *sbi, u32
> nid)
> free(nat_block);
> }
>
> -void write_checkpoint(struct f2fs_sb_info *sbi)
> +void __write_checkpoint(struct f2fs_sb_info *sbi)
> {
> struct f2fs_checkpoint *cp = F2FS_CKPT(sbi);
> struct f2fs_super_block *sb = F2FS_RAW_SUPER(sbi);
> @@ -2144,6 +2144,18 @@ void write_checkpoint(struct f2fs_sb_info *sbi)
> ASSERT(ret >= 0);
> }
>
> +void write_checkpoint(struct f2fs_sb_info *sbi)
> +{
> + int i = 0;
> +
> + for (i = 0; i < 2; i++) {
> + /* write checkpoint out of place first */
> + sbi->cur_cp = sbi->cur_cp % 2 + 1;
> + __write_checkpoint(sbi);
> + f2fs_fsync_device();
Ditto.
Thanks,
> + }
> +}
> +
> void build_nat_area_bitmap(struct f2fs_sb_info *sbi)
> {
> struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
> diff --git a/fsck/sload.c b/fsck/sload.c
> index 2842f2c..53d80fa 100644
> --- a/fsck/sload.c
> +++ b/fsck/sload.c
> @@ -325,6 +325,6 @@ int f2fs_sload(struct f2fs_sb_info *sbi)
> /* flush dirty sit entries */
> flush_sit_entries(sbi);
>
> - write_checkpoint(sbi);
> + __write_checkpoint(sbi);
> return 0;
> }
>
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