On Sep 10, 2019 / 17:12, Chao Yu wrote:
> On 2019/9/10 16:10, Shinichiro Kawasaki wrote:
> > On Sep 09, 2019 / 15:14, Chao Yu wrote:
> >> On 2019/9/6 16:31, Shinichiro Kawasaki wrote:
> >>> On Sep 05, 2019 / 17:58, Chao Yu wrote:
> >>>> Hi Shinichiro,
> >>>>
> >>>> Sorry for the delay.
> >>>>
> >>>> On 2019/9/3 16:37, Shinichiro Kawasaki wrote:
> >>>>> On Sep 02, 2019 / 15:02, Chao Yu wrote:
> >>>>>> On 2019/8/30 18:19, Shin'ichiro Kawasaki wrote:
> >>>>>>> On sudden f2fs shutdown, zoned block device status and f2fs current
> >>>>>>> segment positions in meta data can be inconsistent. When f2fs shutdown
> >>>>>>> happens before write operations completes, 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, the
> >>>>>>> inconsistency causes write operations not at write pointers and
> >>>>>>> "Unaligned write command" error is reported. This error was observed
> >>>>>>> when
> >>>>>>> xfstests test case generic/388 was run with f2fs on a zoned block
> >>>>>>> device.
> >>>>>>>
> >>>>>>> To avoid the error, have f2fs.fsck check consistency between each
> >>>>>>> current
> >>>>>>> segment's position and the write pointer of the zone the current
> >>>>>>> segment
> >>>>>>> points to. If the write pointer goes advance from the current segment,
> >>>>>>> fix the current segment position setting at same as the write pointer
> >>>>>>> position. If the write pointer goes to the zone end, find a new zone
> >>>>>>> and
> >>>>>>> set the current segment position at the new zone start. In case the
> >>>>>>> write
> >>>>>>> pointer is behind the current segment, write zero data at the write
> >>>>>>> pointer position to make write pointer position at same as the current
> >>>>>>> segment.
> >>>>>>>
> >>>>>>> When inconsistencies are found, turn on c.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
> >>>>>>> position fix is done at the beginning of do_fsck() function so that
> >>>>>>> other
> >>>>>>> checks reflect the current segment modification.
> >>>>>>>
> >>>>>>> Also add GET_SEC_FROM_SEG and GET_SEG_FROM_SEC macros in fsck/fsck.h
> >>>>>>> to
> >>>>>>> simplify the code.
> >>>>>>>
> >>>>>>> Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawas...@wdc.com>
> >>>>>>> ---
> >>>>>>> fsck/f2fs.h | 5 ++
> >>>>>>> fsck/fsck.c | 198
> >>>>>>> ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >>>>>>> fsck/fsck.h | 3 +
> >>>>>>> fsck/main.c | 2 +
> >>>>>>> 4 files changed, 208 insertions(+)
> >>>>>>>
> >>>>>>> diff --git a/fsck/f2fs.h b/fsck/f2fs.h
> >>>>>>> index 4dc6698..2c1c2b3 100644
> >>>>>>> --- a/fsck/f2fs.h
> >>>>>>> +++ b/fsck/f2fs.h
> >>>>>>> @@ -337,6 +337,11 @@ 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 8953ca1..a0f6849 100644
> >>>>>>> --- a/fsck/fsck.c
> >>>>>>> +++ b/fsck/fsck.c
> >>>>>>> @@ -2574,6 +2574,190 @@ out:
> >>>>>>> return cnt;
> >>>>>>> }
> >>>>>>>
> >>>>>>> +/*
> >>>>>>> + * Search a free section in main area. Start search from the section
> >>>>>>> specified
> >>>>>>> + * with segno argument toward main area end. Return first segment of
> >>>>>>> the found
> >>>>>>> + * section in segno argument.
> >>>>>>> + */
> >>>>>>> +static int find_next_free_section(struct f2fs_sb_info *sbi,
> >>>>>>> + unsigned int *segno)
> >>>>>>> +{
> >>>>>>> + unsigned int i, sec, section_valid_blocks;
> >>>>>>> + unsigned int end_segno = GET_SEGNO(sbi, SM_I(sbi)->main_blkaddr)
> >>>>>>> + + SM_I(sbi)->main_segments;
> >>>>>>> + unsigned int end_sec = GET_SEC_FROM_SEG(sbi, end_segno);
> >>>>>>> + struct seg_entry *se;
> >>>>>>> + struct curseg_info *cs;
> >>>>>>> +
> >>>>>>> + for (sec = GET_SEC_FROM_SEG(sbi, *segno); sec < end_sec; sec++)
> >>>>>>> {
> >>>>>>> + /* find a section without valid blocks */
> >>>>>>> + section_valid_blocks = 0;
> >>>>>>> + for (i = 0; i < sbi->segs_per_sec; i++) {
> >>>>>>> + se = get_seg_entry(sbi, GET_SEG_FROM_SEC(sbi,
> >>>>>>> sec) + i);
> >>>>>>> + section_valid_blocks += se->valid_blocks;
> >>>>>>
> >>>>>> If we want to find a 'real' free section, we'd better to use
> >>>>>> se->ckpt_valid_blocks (wrapped with get_seg_vblocks()) in where we has
> >>>>>> recorded
> >>>>>> fsynced data count.
> >>>>>
> >>>>> Thanks. When I create next patch series, I will use get_seg_vblocks().
> >>>>> I will rebase to dev-test branch in which get_seg_vblocks() is
> >>>>> available.
> >>>>>
> >>>>>>
> >>>>>>> + }
> >>>>>>> + if (section_valid_blocks)
> >>>>>>> + continue;
> >>>>>>> +
> >>>>>>> + /* check the cursegs do not use the section */
> >>>>>>> + for (i = 0; i < NO_CHECK_TYPE; i++) {
> >>>>>>> + cs = &SM_I(sbi)->curseg_array[i];
> >>>>>>> + if (GET_SEC_FROM_SEG(sbi, cs->segno) == sec)
> >>>>>>> + break;
> >>>>>>> + }
> >>>>>>> + if (i >= NR_CURSEG_TYPE) {
> >>>>>>> + *segno = GET_SEG_FROM_SEC(sbi, sec);
> >>>>>>> + return 0;
> >>>>>>> + }
> >>>>>>> + }
> >>>>>>> +
> >>>>>>> + return -1;
> >>>>>>> +}
> >>>>>>> +
> >>>>>>> +struct write_pointer_check_data {
> >>>>>>> + struct f2fs_sb_info *sbi;
> >>>>>>> + struct device_info *dev;
> >>>>>>> +};
> >>>>>>> +
> >>>>>>> +static int fsck_chk_write_pointer(int i, struct blk_zone *blkz, void
> >>>>>>> *opaque)
> >>>>>>> +{
> >>>>>>> + struct write_pointer_check_data *wpd = opaque;
> >>>>>>> + struct f2fs_sb_info *sbi = wpd->sbi;
> >>>>>>> + struct device_info *dev = wpd->dev;
> >>>>>>> + struct f2fs_fsck *fsck = F2FS_FSCK(sbi);
> >>>>>>> + block_t zone_block, wp_block, wp_blkoff, cs_block, b;
> >>>>>>> + unsigned int zone_segno, wp_segno, new_segno;
> >>>>>>> + struct seg_entry *se;
> >>>>>>> + struct curseg_info *cs;
> >>>>>>> + int cs_index, ret;
> >>>>>>> + int log_sectors_per_block = sbi->log_blocksize - SECTOR_SHIFT;
> >>>>>>> + unsigned int segs_per_zone = sbi->segs_per_sec *
> >>>>>>> sbi->secs_per_zone;
> >>>>>>> + void *zero_blk;
> >>>>>>> +
> >>>>>>> + if (blk_zone_conv(blkz))
> >>>>>>> + return 0;
> >>>>>>> +
> >>>>>>> + zone_block = dev->start_blkaddr
> >>>>>>> + + (blk_zone_sector(blkz) >> log_sectors_per_block);
> >>>>>>> + zone_segno = GET_SEGNO(sbi, zone_block);
> >>>>>>> + wp_block = dev->start_blkaddr
> >>>>>>> + + (blk_zone_wp_sector(blkz) >> log_sectors_per_block);
> >>>>>>> + wp_segno = GET_SEGNO(sbi, wp_block);
> >>>>>>> + wp_blkoff = wp_block - START_BLOCK(sbi, wp_segno);
> >>>>>>> +
> >>>>>>> + /* find the curseg which points to the zone */
> >>>>>>> + for (cs_index = 0; cs_index < NO_CHECK_TYPE; cs_index++) {
> >>>>>>> + cs = &SM_I(sbi)->curseg_array[cs_index];
> >>>>>>> + if (zone_segno <= cs->segno &&
> >>>>>>> + cs->segno < zone_segno + segs_per_zone)
> >>>>>>> + break;
> >>>>>>> + }
> >>>>>>> +
> >>>>>>> + if (cs_index >= NR_CURSEG_TYPE)
> >>>>>>> + return 0;
> >>>>>>> +
> >>>>>>> + /* check write pointer consistency with the curseg in the zone
> >>>>>>> */
> >>>>>>> + cs_block = START_BLOCK(sbi, cs->segno) + cs->next_blkoff;
> >>>>>>> + if (wp_block == cs_block)
> >>>>>>> + return 0;
> >>>>>>> +
> >>>>>>> + if (!c.fix_on) {
> >>>>>>> + MSG(0, "Inconsistent write pointer: "
> >>>>>>> + "curseg %d[0x%x,0x%x] wp[0x%x,0x%x]\n",
> >>>>>>> + cs_index, cs->segno, cs->next_blkoff, wp_segno,
> >>>>>>> wp_blkoff);
> >>>>>>> + fsck->chk.wp_inconsistent_zones++;
> >>>>>>> + return 0;
> >>>>>>> + }
> >>>>>>> +
> >>>>>>> + /*
> >>>>>>> + * If the curseg is in advance from the write pointer, write
> >>>>>>> zero to
> >>>>>>> + * move the write pointer forward to the same position as the
> >>>>>>> curseg.
> >>>>>>> + */
> >>>>>>> + if (wp_block < cs_block) {
> >>>>>>> + ret = 0;
> >>>>>>> + zero_blk = calloc(BLOCK_SZ, 1);
> >>>>>>> + if (!zero_blk)
> >>>>>>> + return -EINVAL;
> >>>>>>> +
> >>>>>>> + FIX_MSG("Advance write pointer to match with curseg %d:
> >>>>>>> "
> >>>>>>> + "[0x%x,0x%x]->[0x%x,0x%x]",
> >>>>>>> + cs_index, wp_segno, wp_blkoff,
> >>>>>>> + cs->segno, cs->next_blkoff);
> >>>>>>> + for (b = wp_block; b < cs_block && !ret; b++)
> >>>>>>> + ret = dev_write_block(zero_blk, b);
> >>>>>>> +
> >>>>>>> + fsck->chk.wp_fixed_zones++;
> >>>>>>> + free(zero_blk);
> >>>>>>> + return ret;
> >>>>>>> + }
> >>>>>>> +
> >>>>>>> + if (wp_segno == zone_segno + segs_per_zone) {
> >>>>>>> + /*
> >>>>>>> + * If the write pointer is in advance from the curseg
> >>>>>>> and at
> >>>>>>> + * the zone end (section end), search a new free zone
> >>>>>>> (section)
> >>>>>>> + * between the curseg and main area end.
> >>>>>>> + */
> >>>>>>> + new_segno = wp_segno;
> >>>>>>> + ret = find_next_free_section(sbi, &new_segno);
> >>>>>>> + if (ret) {
> >>>>>>> + /* search again from main area start */
> >>>>>>> + new_segno = GET_SEGNO(sbi,
> >>>>>>> SM_I(sbi)->main_blkaddr);
> >>>>>>> + ret = find_next_free_section(sbi, &new_segno);
> >>>>>>> + }
> >>>>>>
> >>>>>> If curseg's type is warm node, relocating curseg would ruin warm node
> >>>>>> chain,
> >>>>>> result in losing fsynced data for ever as well.
> >>>>>>
> >>>>>> So I guess we should migrate all dnode blocks chained with
> >>>>>> cs->next_blkoff in
> >>>>>> current section.
> >>>>>>
> >>>>>>> + if (ret) {
> >>>>>>> + MSG(0, "Free section not found\n");
> >>>>>>> + return ret;
> >>>>>>> + }
> >>>>>>> + FIX_MSG("New section for curseg %d:
> >>>>>>> [0x%x,0x%x]->[0x%x,0x%x]",
> >>>>>>> + cs_index, cs->segno, cs->next_blkoff,
> >>>>>>> new_segno, 0);
> >>>>>>> + cs->segno = new_segno;
> >>>>>>> + cs->next_blkoff = 0;
> >>>>>>> + } else {
> >>>>>>> + /*
> >>>>>>> + * If the write pointer is in advance from the curseg
> >>>>>>> within
> >>>>>>> + * the zone, modify the curseg position to be same as
> >>>>>>> the
> >>>>>>> + * write pointer.
> >>>>>>> + */
> >>>>>>> + ASSERT(wp_segno < zone_segno + segs_per_zone);
> >>>>>>> + FIX_MSG("Advance curseg %d: [0x%x,0x%x]->[0x%x,0x%x]",
> >>>>>>> + cs_index, cs->segno, cs->next_blkoff,
> >>>>>>> + wp_segno, wp_blkoff);
> >>>>>>> + cs->segno = wp_segno;
> >>>>>>> + cs->next_blkoff = wp_blkoff;
> >>>>>>
> >>>>>> The same data lose problem here, I guess we'd better handle it with
> >>>>>> the same way
> >>>>>> as above.
> >>>>>>
> >>>>>> Thoughts?
> >>>>>
> >>>>> I created f2fs status with fsync data and warm node chain, and
> >>>>> confirmed the v4
> >>>>> implementation ruins the dnode blocks chain. Hmm.
> >>>>>
> >>>>> My understanding is that when f2fs kernel module recovers the fsync
> >>>>> data, it
> >>>>> sets the warm node curseg position at the start of the fsync data, and
> >>>>> the fsync
> >>>>> data will be overwritten as new nodes created. Is this understanding
> >>>>> correct?
> >>>>
> >>>> Sorry, I'm not sure I've understood you correctly.
> >>>
> >>> Apology is mine, my question was not clear enough.
> >>> And thanks for the explanation below. It helps me to understand better.
> >>>
> >>>> Current recovery flow is:
> >>>> 1) find all valid fsynced dnode in warm node chain
> >>>> 2.a) recover fsynced dnode in memory, and set it dirty
> >>>> 2.b) recover directory entry in memory, and set it dirty
> >>>> 2.c) during regular's dnode recovery, physical blocks indexed by
> >>>> recovered dnode
> >>>> will be revalidated
> >>>> Note: we didn't move any cursegs before 3)
> >>>> 3) relocate all cursegs to new segments
> >>>> 4) trigger checkpoint to persist all recovered data(fs' meta, file's
> >>>> meta/data)
> >>>
> >>> Question, does the step 3) correspond to f2fs_allocate_new_segments(sbi)
> >>> call
> >>> at the end of recover_data()? The f2fs_allocate_new_segments() function
> >>
> >> Yeah, I meant that function.
> >>
> >>> relocates new segments only for DATA cursegs, and it keeps NODE cursegs
> >>> same as
> >>> before the fsync data recovery. Then I thought WARM NODE curseg would not
> >>> change
> >>> by recovery (and still keeps pointing to the fsync recovery data).
> >>
> >> Yes, that's correct. WARM NODE curseg won't change until step 4).
> >
> > Thanks. Following your idea "we can simply adjust to reset all invalid zone
> > and
> > allocate new zone for curseg before data/meta writes" for fix by kernel, I
> > think
> > kernel code change is required to allocate new zones for NODE cursegs also
> > at
> > step 3). WARM NODE curseg should be kept untouched by step 2 completion to
> > refer
> > fsynced dnodes at WARM NODE curseg's next_blkaddr. And at step 4, the fsyced
> > dnodes recovered and set dirty will be written back with one of NODE cursegs
> > (HOT NODE curseg?). At that time, we need to make sure the NODE curseg
> > points to
>
> Directory's dnode goes to hot node area, other file's dnode goes to warm node
> area, the left node goes to cold node area.
>
> > the position consistent with its zone's write pointer.
>
> Yes, before step 4), we should keep f2fs and zoned block device's write
> pointer
> being consistent.
Ok, thanks.
>
> >
> >>>
> >>>>>
> >>>>> If this is the case, I think write pointer inconsistency will happen
> >>>>> even if
> >>>>> fsck does "migrate all dnode blocks" (I assume that the warm node
> >>>>> curseg's next
> >>>>
> >>>> Actually, I notice that scheme's problem is: we've changed zone's write
> >>>> pointer
> >>>> during dnode blocks migration, however if kernel drops recovery, we will
> >>>> still
> >>>> face inconsistent status in between .next_blkaddr and .write_pointer,
> >>>> once we
> >>>> start to write data from .next_blkaddr. So in fsck, after migration, we
> >>>> need to
> >>>> reset .write_pointer to .next_blkaddr.
> >>>>
> >>>> I guess we need to consider four cases:
> >>>>
> >>>> o: support .write_pointer recovery
> >>>> x: not support .write_pointer recovery
> >>>>
> >>>> 1) kernel: o, fsck: x, trigger recovery in kernel
> >>>> 2) kernel: o, fsck: x, not trigger recovery in kernel
> >>>> 3) kernel: x, fsck: o, trigger recovery in kernel
> >>>> 4) kernel: x, fsck: o, not trigger recovery in kernel
> >>>>
> >>>> For 1) and 2), we can simply adjust to reset all invalid zone and
> >>>> allocate new
> >>>> zone for curseg before data/meta writes.
> >>>
> >>> Thanks for the clarification. This approach for case 1) and 2) is simple.
> >>> Let me
> >>> try to create a patch for it.
> >>>
> >>>>
> >>>> For 3) and 4), I haven't figured out a way handling all cases perfectly.
> >>>
> >>> For 3), I suppose fsck cannot fix write pointer inconsistency without
> >>> fsync data
> >>> loss, since recovery is judged and done by kernel. The write pointer
> >>> consistency
> >>> fix after recovery can be done only by kernel.
> >>>
> >>> It is not a good one but one idea is to confirm fsck users to enforce
> >>> fsync data
> >>> loss or not. This could be better than nothing.
> >>>
> >>> For 4), my understanding is that fsync data is not left in the file
> >>> system. I
> >>> think fsck can check fsync data existence and fix write pointer
> >>> consistency, as
> >>> my patch series shows.
> >>
> >> Yeah.
> >>
> >> Let's think about that whether there is a way to cover all cases.
> >>
> >> 1) For non-opened zones, we need to adjust all such zones' write pointer to
> >> zero. I assume that once write pointer is zero, we still can access valid
> >> block
> >> in zone. (recovery may need to revalidate blocks in free segments)
> >
> > When write pointer is reset to zero, all data in the zone gets lost. When we
> > read data in the zone beyond the write pointer, just zero data is read.
> > When any
> > valid block or fsync data is left in a non-opened zone, I think the zone's
> > write
> > pointer should be left as is. Otherwise, if the zone do not have valid
> > block and
> > fsync data, the zone should be reset to avoid unaligned write error.
>
> Okay, if data beyond write pointer is invalid, we should keep write pointer as
> it is if there are fsynced data in that zone.
>
> >
> > One additional check I can think of is to check the last valid block in the
> > zone
> > and write pointer position of the zone. If .write_pointer >=
> > .last_valid_block,
> > , it is ok. If .write_pointer < .last_valid_block, this is a bug of f2fs. In
>
> Sounds reasonable, how can we find last valid block, as you said, content of
> block beyond write pointer is all zero... or you mean curseg's next_blkaddr?
> like the condition 2.c) described?
I think we can get each zone's last valid block referring each segment's valid
block bitmap in SIT. In other words, this is a consistency check between write
pointer and SIT. Is this feasible approach?
>
> > this case, the data in the valid blocks beyond write pointer is just lost,
> > and
> > there is no way to recover this. I think this zone will not be selected for
> > cursegs for further data write in the zone until the zone get discarded. No
> > need to fix write pointer position to avoid unaligned write errors. I wonder
>
> Yes,
>
> > if fsck or kernel should detect and report this case, because users still
> > use
> > the f2fs partition without any action. May I ask your opinion?
>
> If we can detect that, I think it should be reported.
I see, thanks for the comment.
>
> >
> >>
> >> 2) For opened zones (cursegs point to)
> >> 2.a) .write_pointer == .next_blkaddr, no need to handle
> >> 2.b) .write_pointer > .next_blkaddr, that should be the common state in
> >> sudden
> >> power-off case. It needs to reset .write_pointer to .next_blkaddr.
Sorry but let me amend. I have just noticed that the fix above is not possible.
We cannot set .write_pointer at .next_blkaddr, because write pointers cannot be
reset to desired position. It only can be reset to zero (at the zone start).
Instead of resetting .write_pointer, how about to fix by allocating a new zone
to
the curseg for 2.b) in same manner as 2.c)?
> >
> > Agreed. To be more precise, if fsync data is recorded after .next_blkaddr,
> > we
> > need to allocate a new zone to the curseg after fsync data recovery.
> >
> >> 2.c) .write_pointer < .next_blkaddr, should be a bug of f2fs, we should
> >> have
> >> lost datas in the range of [.write_pointer, .next_blkaddr] at least, if
> >> we're
> >> sure about that there is no valid data existed out side of .write_pointer?
> >> can we?
> >
> > As you note, this is a bug and we lost the data in the range of
> > [.write_pointer,
> > .next_blkaddr]. We should leave the write pointer as is to keep the data in
> > the
> > zone, and allocate a new zone to the curseg to avoid unaligned write errors.
>
> Okay.
>
> >
> >>
> >> 3) f2fs_allocate_new_segments() may reset data type cursegs' position, I'd
> >> like
> >> to know what's the value of -z option we configured, if we configured as
> >> one
> >> zone contains one section, no matter kernel triggers recovery or not (via
> >> set
> >> disable_roll_forward option), the write pointer consistency should has
> >> been kept
> >> in all cases. Otherwise (one zone contains multiple sections), if kernel
> >> doesn't
> >> support .write_pointer recovery, f2fs_allocate_new_segments() can make
> >> .next_blkaddr larger than .write_pointer in the same zone.
> >
> > "Single section per zone" is a key design of the f2fs zoned block device
> > support. For zoned block devices, mkfs.f2fs requires -m option. When -m
> > options is set, mkfs sets '1' to c.secs_per_zone regardless of the -z option
> > (refer f2fs_get_device_info() in lib/libf2fs.c). With this prerequisite,
>
> Oh, correct, thanks for noticing that. I did miss that we only use -m option
> for
> zoned block device.
>
> > I think new zones are allocated for DATA cursegs in
> > f2fs_allocate_new_segment() and its sub-function call path.
> >
> >>
> >> Let me know, if I'm missing sth.
> >
> > Assuming fsync data is the only one exceptional data which is read beyond
> > the
> > cursegs' next_blkoff, this discussion looks comprehensive for me:
> >
> > - with and without kernel write pointer fix
> > - with and without fsync data recovery
> > - open/non-open zones (zones cursegs point to, zones cursegs do not point
> > to)
> >
> > All fs meta data in front of main segments are stored in conventional zones
> > which do not have write pointers (refer f2fs_prepare_super_block() in mkfs/
> > f2fs_format.c). Just we need to care about write pointer consistency for the
> > main data area.
>
> Agreed,
--
Best Regards,
Shin'ichiro Kawasaki
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