Re: [f2fs-dev] [PATCH 2/2] f2fs: Check write pointer consistency of non-open zones

[Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>]

On Oct 18, 2019 / 15:38, Shin'ichiro Kawasaki wrote:
> To catch f2fs bugs in write pointer handling code for zoned block
> devices, check write pointers of non-open zones that current segments do
> not point to. Do this check at mount time, after the fsync data recovery
> and current segments' write pointer consistency fix. Check two items
> comparing write pointers with valid block maps in SIT.
> 
> The first item is check for zones with no valid blocks. When there is no
> valid blocks in a zone, the write pointer should be at the start of the
> zone. If not, next write operation to the zone will cause unaligned write
> error. If write pointer is not at the zone start, make mount fail and ask
> users to run fsck.
> 
> The second item is check between the write pointer position and the last
> valid block in the zone. It is unexpected that the last valid block
> position is beyond the write pointer. In such a case, report as the bug.
> Fix is not required for such zone, because the zone is not selected for
> next write operation until the zone get discarded.
> 
> Also move a constant F2FS_REPORT_ZONE from super.c to f2fs.h to use it
> in segment.c also.
> 
> Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
> ---
>  fs/f2fs/f2fs.h    |   3 +
>  fs/f2fs/segment.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++
>  fs/f2fs/super.c   |  11 ++--
>  3 files changed, 154 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 0216282c5b80..e8524be17852 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -3137,6 +3137,7 @@ int f2fs_lookup_journal_in_cursum(struct f2fs_journal *journal, int type,
>  			unsigned int val, int alloc);
>  void f2fs_flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc);
>  int f2fs_fix_curseg_write_pointer(struct f2fs_sb_info *sbi, bool check_only);
> +int f2fs_check_write_pointer(struct f2fs_sb_info *sbi);
>  int f2fs_build_segment_manager(struct f2fs_sb_info *sbi);
>  void f2fs_destroy_segment_manager(struct f2fs_sb_info *sbi);
>  int __init f2fs_create_segment_manager_caches(void);
> @@ -3610,6 +3611,8 @@ static inline bool f2fs_blkz_is_seq(struct f2fs_sb_info *sbi, int devi,
>  
>  	return test_bit(zno, FDEV(devi).blkz_seq);
>  }
> +
> +#define F2FS_REPORT_NR_ZONES   4096
>  #endif
>  
>  static inline bool f2fs_hw_should_discard(struct f2fs_sb_info *sbi)
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 2b6e637dd6d3..d00d3f16b750 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -4333,6 +4333,128 @@ static int sanity_check_curseg(struct f2fs_sb_info *sbi)
>  
>  #ifdef CONFIG_BLK_DEV_ZONED
>  
> +static int check_zone_write_pointer(struct f2fs_sb_info *sbi,
> +				    struct f2fs_dev_info *fdev,
> +				    struct blk_zone *zone)
> +{
> +	unsigned int s, wp_segno, wp_blkoff, zone_secno, zone_segno, segno;
> +	block_t zone_block, wp_block, last_valid_block, b;
> +	unsigned int log_sectors_per_block = sbi->log_blocksize - SECTOR_SHIFT;
> +	int i;
> +	struct seg_entry *se;
> +
> +	wp_block = fdev->start_blk + (zone->wp >> log_sectors_per_block);
> +	wp_segno = GET_SEGNO(sbi, wp_block);
> +	wp_blkoff = wp_block - START_BLOCK(sbi, wp_segno);
> +	zone_block = fdev->start_blk + (zone->start >> log_sectors_per_block);
> +	zone_segno = GET_SEGNO(sbi, zone_block);
> +	zone_secno = GET_SEC_FROM_SEG(sbi, zone_segno);

In same manner as I commnted for fsck patch, the zones of this function can be
out of main segment range when size parameter is provided. Will add check to
ensure the zone is within the main segment range.

Will post next version soon, reflectin my comment above.

--
Best Regards,
Shin'ichiro Kawasaki

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