Re: [f2fs-dev] [PATCH v3 2/2] f2fs: Check write pointer consistency of non-open zones

[Chao Yu <yuchao0@huawei.com>]

On 2019/11/14 16:19, 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. Or when fsync data
> recovery is disabled by mount option, do the check when there is no fsync
> data.
> 
> 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 a 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 | 149 ++++++++++++++++++++++++++++++++++++++++++++++
>  fs/f2fs/super.c   |  16 ++++-
>  3 files changed, 165 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index a2e24718c13b..1bb64950d793 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);
> +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 6ece146dab34..29e3b6f62f8c 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -4333,6 +4333,133 @@ 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 wp_segno, wp_blkoff, zone_secno, zone_segno, segno;
> +	block_t zone_block, wp_block, last_valid_block;
> +	unsigned int log_sectors_per_block = sbi->log_blocksize - SECTOR_SHIFT;
> +	int i, s, b;
> +	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);
> +
> +	if (zone_segno >= MAIN_SEGS(sbi))
> +		return 0;
> +
> +	/*
> +	 * Skip check of zones cursegs point to, since
> +	 * fix_curseg_write_pointer() checks them.
> +	 */
> +	for (i = 0; i < NO_CHECK_TYPE; i++)
> +		if (zone_secno == GET_SEC_FROM_SEG(sbi,
> +						   CURSEG_I(sbi, i)->segno))
> +			return 0;
> +
> +	/*
> +	 * Get last valid block of the zone.
> +	 */
> +	last_valid_block = zone_block - 1;
> +	for (s = sbi->segs_per_sec - 1; s >= 0; s--) {
> +		segno = zone_segno + s;
> +		se = get_seg_entry(sbi, segno);
> +		for (b = sbi->blocks_per_seg - 1; b >= 0; b--)
> +			if (f2fs_test_bit(b, se->cur_valid_map)) {
> +				last_valid_block = START_BLOCK(sbi, segno) + b;
> +				break;
> +			}
> +		if (last_valid_block >= zone_block)
> +			break;
> +	}
> +
> +	/*
> +	 * If last valid block is beyond the write pointer, report the
> +	 * inconsistency. This inconsistency does not cause write error
> +	 * because the zone will not be selected for write operation until
> +	 * it get discarded. Just report it.
> +	 */
> +	if (last_valid_block >= wp_block) {
> +		f2fs_notice(sbi, "Valid block beyond write pointer: "
> +			    "valid block[0x%x,0x%x] wp[0x%x,0x%x]",
> +			    GET_SEGNO(sbi, last_valid_block),
> +			    GET_BLKOFF_FROM_SEG0(sbi, last_valid_block),
> +			    wp_segno, wp_blkoff);
> +		return 0;
> +	}
> +
> +	/*
> +	 * If there is no valid block in the zone and if write pointer is
> +	 * not at zone start, report the error to run fsck.

So we only need to report this as inconsistent status in the condition of
discard has been triggered, right? otherwise, f2fs will trigger discard later
to reset zone->wp before opening this zone?

Thanks,

> +	 */
> +	if (last_valid_block + 1 == zone_block && zone->wp != zone->start) {
> +		f2fs_notice(sbi,
> +			    "Zone without valid block has non-zero write "
> +			    "pointer, run fsck to fix: wp[0x%x,0x%x]",
> +			    wp_segno, wp_blkoff);
> +		f2fs_stop_checkpoint(sbi, true);
> +		set_sbi_flag(sbi, SBI_NEED_FSCK);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int check_dev_write_pointer(struct f2fs_sb_info *sbi,
> +				   struct f2fs_dev_info *fdev) {
> +	sector_t nr_sectors = fdev->bdev->bd_part->nr_sects;
> +	sector_t sector = 0;
> +	struct blk_zone *zones;
> +	unsigned int i, nr_zones;
> +	unsigned int n = 0;
> +	int err = -EIO;
> +
> +	if (!bdev_is_zoned(fdev->bdev))
> +		return 0;
> +
> +	zones = f2fs_kzalloc(sbi,
> +			     array_size(F2FS_REPORT_NR_ZONES,
> +					sizeof(struct blk_zone)),
> +			     GFP_KERNEL);
> +	if (!zones)
> +		return -ENOMEM;
> +
> +	/* Get block zones type */
> +	while (zones && sector < nr_sectors) {
> +
> +		nr_zones = F2FS_REPORT_NR_ZONES;
> +		err = blkdev_report_zones(fdev->bdev, sector, zones, &nr_zones);
> +		if (err)
> +			break;
> +		if (!nr_zones) {
> +			err = -EIO;
> +			break;
> +		}
> +
> +		for (i = 0; i < nr_zones; i++) {
> +			if (zones[i].type == BLK_ZONE_TYPE_SEQWRITE_REQ) {
> +				err = check_zone_write_pointer(sbi, fdev,
> +							       &zones[i]);
> +				if (err)
> +					break;
> +			}
> +			sector += zones[i].len;
> +			n++;
> +		}
> +		if (err)
> +			break;
> +	}
> +
> +	kvfree(zones);
> +
> +	return err;
> +}
> +
>  static struct f2fs_dev_info *get_target_zoned_dev(struct f2fs_sb_info *sbi,
>  						  block_t zone_blkaddr)
>  {
> @@ -4399,6 +4526,10 @@ static int fix_curseg_write_pointer(struct f2fs_sb_info *sbi, int type)
>  		    "curseg[0x%x,0x%x]", type, cs->segno, cs->next_blkoff);
>  	allocate_segment_by_default(sbi, type, true);
>  
> +	/* check consistency of the zone curseg pointed to */
> +	if (check_zone_write_pointer(sbi, zbd, &zone))
> +		return -EIO;
> +
>  	/* check newly assigned zone */
>  	cs_section = GET_SEC_FROM_SEG(sbi, cs->segno);
>  	cs_zone_block = START_BLOCK(sbi, GET_SEG_FROM_SEC(sbi, cs_section));
> @@ -4444,11 +4575,29 @@ int f2fs_fix_curseg_write_pointer(struct f2fs_sb_info *sbi)
>  
>  	return 0;
>  }
> +
> +int f2fs_check_write_pointer(struct f2fs_sb_info *sbi)
> +{
> +	int i, ret;
> +
> +	for (i = 0; i < sbi->s_ndevs; i++) {
> +		ret = check_dev_write_pointer(sbi, &FDEV(i));
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
>  #else
>  int f2fs_fix_curseg_write_pointer(struct f2fs_sb_info *sbi)
>  {
>  	return 0;
>  }
> +
> +int f2fs_check_write_pointer(struct f2fs_sb_info *sbi)
> +{
> +	return 0;
> +}
>  #endif
>  
>  /*
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 1443cee15863..8ca772670c67 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -2890,8 +2890,6 @@ static int init_blkz_info(struct f2fs_sb_info *sbi, int devi)
>  	if (!FDEV(devi).blkz_seq)
>  		return -ENOMEM;
>  
> -#define F2FS_REPORT_NR_ZONES   4096
> -
>  	zones = f2fs_kzalloc(sbi,
>  			     array_size(F2FS_REPORT_NR_ZONES,
>  					sizeof(struct blk_zone)),
> @@ -3509,7 +3507,8 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>  
>  		err = f2fs_recover_fsync_data(sbi, false);
>  		if (err < 0) {
> -			if (err != -ENOMEM)
> +			if (err != -ENOMEM &&
> +			    !is_sbi_flag_set(sbi, SBI_NEED_FSCK))
>  				skip_recovery = true;
>  			need_fsck = true;
>  			f2fs_err(sbi, "Cannot recover all fsync data errno=%d",
> @@ -3525,6 +3524,17 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>  			goto free_meta;
>  		}
>  	}
> +
> +	/*
> +	 * If the f2fs is not readonly and fsync data recovery succeeds,
> +	 * check zoned block devices' write pointer consistency.
> +	 */
> +	if (!err && !f2fs_readonly(sb) && f2fs_sb_has_blkzoned(sbi)) {
> +		err = f2fs_check_write_pointer(sbi);
> +		if (err)
> +			goto free_meta;
> +	}
> +
>  reset_checkpoint:
>  	/* f2fs_recover_fsync_data() cleared this already */
>  	clear_sbi_flag(sbi, SBI_POR_DOING);
> 


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