Re: [f2fs-dev] [PATCH v6 7/8] fsck: Check write pointer consistency of open zones

[Chao Yu <yuchao0@huawei.com>]

On 2019/11/6 17:45, Shinichiro Kawasaki wrote:
> On Nov 05, 2019 / 19:06, Chao Yu wrote:
>> On 2019/10/28 14:55, Shin'ichiro Kawasaki wrote:
>>> On sudden f2fs shutdown, write pointers of zoned block devices can go
>>> further but f2fs meta data keeps current segments at positions before the
>>> write operations. After remounting the f2fs, this inconsistency causes
>>> write operations not at write pointers and "Unaligned write command"
>>> error is reported.
>>>
>>> To avoid the error, have f2fs.fsck check consistency of write pointers
>>> of open zones that current segments point to. Compare each current
>>> segment's position and the write pointer position of the open zone. If
>>> inconsistency is found and 'fix_on' flag is set, assign a new zone to the
>>> current segment and check the newly assigned zone has write pointer at
>>> the zone start. Leave the original zone as is to keep data recorded in
>>> it.
>>>
>>> To care about fsync data, refer each seg_entry's ckpt_valid_map to get
>>> the last valid block in the zone. If the last valid block is beyond the
>>> current segments position, fsync data exits in the zone. In case fsync
>>> data exists, do not assign a new zone to the current segment not to lose
>>> the fsync data. It is expected that the kernel replay the fsync data and
>>> fix the write pointer inconsistency at mount time.
>>>
>>> Also check consistency between write pointer of the zone the current
>>> segment points to with valid block maps of the zone. If the last valid
>>> block is beyond the write pointer position, report to indicate f2fs bug.
>>> If 'fix_on' flag is set, assign a new zone to the current segment.
>>>
>>> When inconsistencies are found, turn on 'bug_on' flag in fsck_verify() to
>>> ask users to fix them or not. When inconsistencies get fixed, turn on
>>> 'force' flag in fsck_verify() to enforce fixes in following checks.
>>>
>>> This check and fix is done twice. The first is done at the beginning of
>>> do_fsck() function so that other fixes can reflect the current segment
>>> modification. The second is done in fsck_verify() to reflect updated meta
>>> data by other fixes.
>>>
>>> Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
>>> ---
>>>  fsck/f2fs.h  |   5 ++
>>>  fsck/fsck.c  | 154 +++++++++++++++++++++++++++++++++++++++++++++++++++
>>>  fsck/fsck.h  |   3 +
>>>  fsck/main.c  |   2 +
>>>  fsck/mount.c |  49 +++++++++++++++-
>>>  5 files changed, 212 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/fsck/f2fs.h b/fsck/f2fs.h
>>> index 399c74d..07513cb 100644
>>> --- a/fsck/f2fs.h
>>> +++ b/fsck/f2fs.h
>>> @@ -429,6 +429,11 @@ static inline block_t __end_block_addr(struct f2fs_sb_info *sbi)
>>>  #define GET_BLKOFF_FROM_SEG0(sbi, blk_addr)				\
>>>  	(GET_SEGOFF_FROM_SEG0(sbi, blk_addr) & (sbi->blocks_per_seg - 1))
>>>  
>>> +#define GET_SEC_FROM_SEG(sbi, segno)					\
>>> +	((segno) / (sbi)->segs_per_sec)
>>> +#define GET_SEG_FROM_SEC(sbi, secno)					\
>>> +	((secno) * (sbi)->segs_per_sec)
>>> +
>>>  #define FREE_I_START_SEGNO(sbi)						\
>>>  	GET_SEGNO_FROM_SEG0(sbi, SM_I(sbi)->main_blkaddr)
>>>  #define GET_R2L_SEGNO(sbi, segno)	(segno + FREE_I_START_SEGNO(sbi))
>>> diff --git a/fsck/fsck.c b/fsck/fsck.c
>>> index 2ae3bd5..e0eda4e 100644
>>> --- a/fsck/fsck.c
>>> +++ b/fsck/fsck.c
>>> @@ -2181,6 +2181,125 @@ static void fix_checkpoints(struct f2fs_sb_info *sbi)
>>>  	fix_checkpoint(sbi);
>>>  }
>>>  
>>> +#ifdef HAVE_LINUX_BLKZONED_H
>>> +
>>> +/*
>>> + * Refer valid block map and return offset of the last valid block in the zone.
>>> + * Obtain valid block map from SIT and fsync data.
>>> + * If there is no valid block in the zone, return -1.
>>> + */
>>> +static int last_vblk_off_in_zone(struct f2fs_sb_info *sbi,
>>> +				 unsigned int zone_segno)
>>> +{
>>> +	unsigned int s;
>>> +	unsigned int segs_per_zone = sbi->segs_per_sec * sbi->secs_per_zone;
>>> +	struct seg_entry *se;
>>> +	block_t b;
>>> +	int ret = -1;
>>> +
>>> +	for (s = 0; s < segs_per_zone; s++) {
>>> +		se = get_seg_entry(sbi, zone_segno + s);
>>> +
>>> +		/*
>>> +		 * Refer not cur_valid_map but ckpt_valid_map which reflects
>>> +		 * fsync data.
>>> +		 */
>>> +		ASSERT(se->ckpt_valid_map);
>>> +		for (b = 0; b < sbi->blocks_per_seg; b++)
>>> +			if (f2fs_test_bit(b, (const char*)se->ckpt_valid_map))
>>> +				ret = b + (s << sbi->log_blocks_per_seg);
>>
>> Minor thing, I guess we only need to find last valid block in target zone?
>>
>> int s, b;
>>
>> for (s = segs_per_zone - 1; s >= 0; s--) {
>> 	for (b = sbi->blocks_per_seg - 1; b >= 0; b--)
>> 		if (f2fs_test_bit(b, (const char*)se->ckpt_valid_map)) {
>> 			ret = b + (s << sbi->log_blocks_per_seg);
>> 			break;
>> 		}
>> }
> 
> Yes, reveresed search is the better. Will modify the code as suggested.
> 
>>
>>> +	}
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int check_curseg_write_pointer(struct f2fs_sb_info *sbi, int type)
>>> +{
>>> +	struct curseg_info *curseg = CURSEG_I(sbi, type);
>>> +	struct f2fs_fsck *fsck = F2FS_FSCK(sbi);
>>> +	struct blk_zone blkz;
>>> +	block_t cs_block, wp_block, zone_last_vblock;
>>> +	u_int64_t cs_sector, wp_sector;
>>> +	int i, ret;
>>> +	unsigned int zone_segno;
>>> +	int log_sectors_per_block = sbi->log_blocksize - SECTOR_SHIFT;
>>> +
>>> +	/* get the device the curseg points to */
>>> +	cs_block = START_BLOCK(sbi, curseg->segno) + curseg->next_blkoff;
>>> +	for (i = 0; i < MAX_DEVICES; i++) {
>>> +		if (!c.devices[i].path)
>>> +			break;
>>> +		if (c.devices[i].start_blkaddr <= cs_block &&
>>> +		    cs_block <= c.devices[i].end_blkaddr)
>>> +			break;
>>> +	}
>>> +
>>> +	if (i >= MAX_DEVICES)
>>> +		return -EINVAL;
>>> +
>>> +	/* get write pointer position of the zone the curseg points to */
>>> +	cs_sector = (cs_block - c.devices[i].start_blkaddr)
>>> +		<< log_sectors_per_block;
>>> +	ret = f2fs_report_zone(i, cs_sector, &blkz);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	if (blk_zone_type(&blkz) != BLK_ZONE_TYPE_SEQWRITE_REQ)
>>> +		return 0;
>>> +
>>> +	/* check consistency between the curseg and the write pointer */
>>> +	wp_block = c.devices[i].start_blkaddr +
>>> +		(blk_zone_wp_sector(&blkz) >> log_sectors_per_block);
>>> +	wp_sector = blk_zone_wp_sector(&blkz);
>>> +
>>> +	if (cs_sector == wp_sector)
>>> +		return 0;
>>> +
>>> +	if (cs_sector > wp_sector) {
>>> +		MSG(0, "Inconsistent write pointer with curseg %d: "
>>> +		    "curseg %d[0x%x,0x%x] > wp[0x%x,0x%x]\n",
>>> +		    type, type, curseg->segno, curseg->next_blkoff,
>>> +		    GET_SEGNO(sbi, wp_block), OFFSET_IN_SEG(sbi, wp_block));
>>> +		fsck->chk.wp_inconsistent_zones++;
>>> +		return -EINVAL;
>>> +	}
>>> +
>>> +	MSG(0, "Write pointer goes advance from curseg %d: "
>>> +	    "curseg %d[0x%x,0x%x] wp[0x%x,0x%x]\n",
>>> +	    type, type, curseg->segno, curseg->next_blkoff,
>>> +	    GET_SEGNO(sbi, wp_block), OFFSET_IN_SEG(sbi, wp_block));
>>> +
>>> +	zone_segno = GET_SEG_FROM_SEC(sbi,
>>> +				      GET_SEC_FROM_SEG(sbi, curseg->segno));
>>> +	zone_last_vblock = START_BLOCK(sbi, zone_segno) +
>>> +		last_vblk_off_in_zone(sbi, zone_segno);
>>> +
>>> +	/*
>>> +	 * If fsync data exists between the curseg and the last valid block,
>>> +	 * it is not an error to fix. Leave it for kernel to recover later.
>>> +	 */
>>> +	if (cs_block <= zone_last_vblock) {
>>
>> According to above comments, should condition be?
>>
>> if (cs_block < zone_last_vblock && zone_last_vblock <= wp_block)
>>
> 
> To be precise, cs_block points to curseg->next_blkoff, which is the block
> curseg will write in the next write request. Then, if cs_block equals to
> zone_last_vblock, it means that the block curseg->next_blkoff points to
> already have valid block and fsync data. Then, comparator between cs_block
> and zone_last_vblock should be "<=".

You're right.

> 
> I agree that it is the better to check zone_last_vblock with wp_block.
> wp_block corresponds to the write pointer position that next write will be
> made. It wp_block equals to zone_last_vblock, it means that unexpected data
> is written beyond the write pointer. Then, comparator should be "<" between
> zone_last_vblock and wp_block.

Oh, so wp has almost the same meaning to .next_blkoff in f2fs, it points to next
free block/sector. I will keep that in mind.

> 
> In short, I suggest the condition check below as the good one.
> 
> if (cs_block <= zone_last_vblock && zone_last_vblock < wp_block)

It's fine to me. :)

Thanks,

> 
>>> +		MSG(0, "Curseg has fsync data: curseg %d[0x%x,0x%x] "
>>> +		    "last valid block in zone[0x%x,0x%x]\n",
>>> +		    type, curseg->segno, curseg->next_blkoff,
>>> +		    GET_SEGNO(sbi, zone_last_vblock),
>>> +		    OFFSET_IN_SEG(sbi, zone_last_vblock));
>>> +		return 0;
>>> +	}
>>> +
>>> +	fsck->chk.wp_inconsistent_zones++;
>>> +	return -EINVAL;
>>> +}
>>> +
>>> +#else
>>> +
>>> +static int check_curseg_write_pointer(struct f2fs_sb_info *sbi, int type)
>>> +{
>>> +	return 0;
>>> +}
>>> +
>>> +#endif
>>> +
>>>  int check_curseg_offset(struct f2fs_sb_info *sbi, int type)
>>>  {
>>>  	struct curseg_info *curseg = CURSEG_I(sbi, type);
>>> @@ -2209,6 +2328,10 @@ int check_curseg_offset(struct f2fs_sb_info *sbi, int type)
>>>  			return -EINVAL;
>>>  		}
>>>  	}
>>> +
>>> +	if (c.zoned_model == F2FS_ZONED_HM)
>>> +		return check_curseg_write_pointer(sbi, type);
>>> +
>>>  	return 0;
>>>  }
>>>  
>>> @@ -2628,6 +2751,23 @@ out:
>>>  	return cnt;
>>>  }
>>>  
>>> +/*
>>> + * Check and fix consistency with write pointers at the beginning of
>>> + * fsck so that following writes by fsck do not fail.
>>> + */
>>> +void fsck_chk_and_fix_write_pointers(struct f2fs_sb_info *sbi)
>>> +{
>>> +	struct f2fs_fsck *fsck = F2FS_FSCK(sbi);
>>> +
>>> +	if (c.zoned_model != F2FS_ZONED_HM)
>>> +		return;
>>> +
>>> +	if (check_curseg_offsets(sbi) && c.fix_on) {
>>> +		fix_curseg_info(sbi);
>>> +		fsck->chk.wp_fixed = 1;
>>> +	}
>>> +}
>>> +
>>>  int fsck_chk_curseg_info(struct f2fs_sb_info *sbi)
>>>  {
>>>  	struct curseg_info *curseg;
>>> @@ -2678,6 +2818,20 @@ int fsck_verify(struct f2fs_sb_info *sbi)
>>>  
>>>  	printf("\n");
>>>  
>>> +	if (c.zoned_model == F2FS_ZONED_HM) {
>>> +		printf("[FSCK] Write pointers consistency                    ");
>>> +		if (fsck->chk.wp_inconsistent_zones == 0x0) {
>>> +			printf(" [Ok..]\n");
>>> +		} else {
>>> +			printf(" [Fail] [0x%x]\n",
>>> +			       fsck->chk.wp_inconsistent_zones);
>>> +			c.bug_on = 1;
>>> +		}
>>> +
>>> +		if (fsck->chk.wp_fixed && c.fix_on)
>>> +			force = 1;
>>> +	}
>>> +
>>>  	if (c.feature & cpu_to_le32(F2FS_FEATURE_LOST_FOUND)) {
>>>  		for (i = 0; i < fsck->nr_nat_entries; i++)
>>>  			if (f2fs_test_bit(i, fsck->nat_area_bitmap) != 0)
>>> diff --git a/fsck/fsck.h b/fsck/fsck.h
>>> index 75052d8..c4432e8 100644
>>> --- a/fsck/fsck.h
>>> +++ b/fsck/fsck.h
>>> @@ -80,6 +80,8 @@ struct f2fs_fsck {
>>>  		u32 multi_hard_link_files;
>>>  		u64 sit_valid_blocks;
>>>  		u32 sit_free_segs;
>>> +		u32 wp_fixed;
>>> +		u32 wp_inconsistent_zones;
>>>  	} chk;
>>>  
>>>  	struct hard_link_node *hard_link_list_head;
>>> @@ -162,6 +164,7 @@ int fsck_chk_inline_dentries(struct f2fs_sb_info *, struct f2fs_node *,
>>>  		struct child_info *);
>>>  void fsck_chk_checkpoint(struct f2fs_sb_info *sbi);
>>>  int fsck_chk_meta(struct f2fs_sb_info *sbi);
>>> +void fsck_chk_and_fix_write_pointers(struct f2fs_sb_info *);
>>>  int fsck_chk_curseg_info(struct f2fs_sb_info *);
>>>  void pretty_print_filename(const u8 *raw_name, u32 len,
>>>  			   char out[F2FS_PRINT_NAMELEN], int enc_name);
>>> diff --git a/fsck/main.c b/fsck/main.c
>>> index 8c62a14..9a7d499 100644
>>> --- a/fsck/main.c
>>> +++ b/fsck/main.c
>>> @@ -602,6 +602,8 @@ static void do_fsck(struct f2fs_sb_info *sbi)
>>>  
>>>  	print_cp_state(flag);
>>>  
>>> +	fsck_chk_and_fix_write_pointers(sbi);
>>> +
>>>  	fsck_chk_curseg_info(sbi);
>>>  
>>>  	if (!c.fix_on && !c.bug_on) {
>>> diff --git a/fsck/mount.c b/fsck/mount.c
>>> index 2979865..5085e6c 100644
>>> --- a/fsck/mount.c
>>> +++ b/fsck/mount.c
>>> @@ -2465,6 +2465,52 @@ void set_section_type(struct f2fs_sb_info *sbi, unsigned int segno, int type)
>>>  	}
>>>  }
>>>  
>>> +#ifdef HAVE_LINUX_BLKZONED_H
>>> +
>>> +static bool write_pointer_at_zone_start(struct f2fs_sb_info *sbi,
>>> +					unsigned int zone_segno)
>>> +{
>>> +	u_int64_t sector;
>>> +	struct blk_zone blkz;
>>> +	block_t block = START_BLOCK(sbi, zone_segno);
>>> +	int log_sectors_per_block = sbi->log_blocksize - SECTOR_SHIFT;
>>> +	int ret, j;
>>> +
>>> +	if (c.zoned_model != F2FS_ZONED_HM)
>>> +		return true;
>>> +
>>> +	for (j = 0; j < MAX_DEVICES; j++) {
>>> +		if (!c.devices[j].path)
>>> +			break;
>>> +		if (c.devices[j].start_blkaddr <= block &&
>>> +		    block <= c.devices[j].end_blkaddr)
>>> +			break;
>>> +	}
>>> +
>>> +	if (j >= MAX_DEVICES)
>>> +		return false;
>>> +
>>> +	sector = (block - c.devices[j].start_blkaddr) << log_sectors_per_block;
>>> +	ret = f2fs_report_zone(j, sector, &blkz);
>>> +	if (ret)
>>> +		return false;
>>> +
>>> +	if (blk_zone_type(&blkz) != BLK_ZONE_TYPE_SEQWRITE_REQ)
>>> +		return true;
>>> +
>>> +	return blk_zone_sector(&blkz) == blk_zone_wp_sector(&blkz);
>>> +}
>>> +
>>> +#else
>>> +
>>> +static bool write_pointer_at_zone_start(struct f2fs_sb_info *sbi,
>>> +					unsigned int zone_segno)
>>> +{
>>> +	return true;
>>> +}
>>> +
>>> +#endif
>>> +
>>>  int find_next_free_block(struct f2fs_sb_info *sbi, u64 *to, int left, int want_type, bool new_sec)
>>>  {
>>>  	struct f2fs_super_block *sb = F2FS_RAW_SUPER(sbi);
>>> @@ -2517,7 +2563,8 @@ int find_next_free_block(struct f2fs_sb_info *sbi, u64 *to, int left, int want_t
>>>  					break;
>>>  			}
>>>  
>>> -			if (i == sbi->segs_per_sec) {
>>> +			if (i == sbi->segs_per_sec &&
>>> +			    write_pointer_at_zone_start(sbi, segno)) {
>>>  				set_section_type(sbi, segno, want_type);
>>>  				return 0;
>>>  			}
>>>
> 
> --
> Best Regards,
> Shin'ichiro Kawasaki.
> 


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