Re: [f2fs-dev] [PATCH] f2fs: avoid frequent costly fsck triggers

From: Chao Yu
Date: Thu Nov 29 2018 - 22:10:52 EST

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On 2018/11/30 10:35, Sheng Yong wrote:
> Hi, Jaegeuk and Chao,
>
> On 2018/11/29 1:48, Jaegeuk Kim wrote:
>> On 11/28, Chao Yu wrote:
>>> On 2018/11/28 16:10, Jaegeuk Kim wrote:
>>>> On 11/28, Chao Yu wrote:
>>>>> Hi Jaeguek,
>>>>>
>>>>> On 2018/11/28 15:31, Jaegeuk Kim wrote:
>>>>>> If we want to re-enable nat_bits, we rely on fsck which requires full scan
>>>>>> of directory tree. Let's do that by regular fsck or unclean shutdown.
>>>>>
>>>>> Reviewed-by: Chao Yu <yuchao0@xxxxxxxxxx>
>>>>>
>>>>> BTW, I have patch made some month ago...
>>>>>
>>>>> In order to detect nat_bits disabling, could we introduce one more flag for
>>>>> fsck?
>>>>
>>>> Do we have a way to enable nat_bits very quickly in fsck?
>>>
>>> For image with SBI_NATBIT_NEED_REPAIR flag, can we just check metadata and
>>> rebuild nat_bits based on verified nat blocks/journals?
>>
>> I'm leaning to rely on full scan to enable nat_bits again. We may add a mount
>> count or timer to trigger fsck regularly?
>
> I'm afraid regular full fsck would give us bad experience of booting time.
> FYI, 256GB storage, which is filled with small files, costs almost 10 min
> to do a full fsck. And it seems larger capacity storages are on the way.

Agreed.

> So, is it worth doing that only to enable nat_bits (plus checking f2fs
> consistent not that necessarily)?

In android environment, I think it may be too expensive for adding nat_bits
by triggering full scan by fsck during boot time.

If we can update all nat bitmap in free time after mount, maybe we can
rebuild nat_bits based on full nat bitmap during umount, which can be
cheaper than rebuiding in userspace.

Thanks,

>
> Thanks
>>
>>>
>>> Thanks,
>>>
>>>>
>>>>>
>>>>> >From 86e8bdb2faeec904944bb6621073f4f7de51cc2d Mon Sep 17 00:00:00 2001
>>>>> From: Chao Yu <yuchao0@xxxxxxxxxx>
>>>>> Date: Sun, 9 Sep 2018 05:40:20 +0800
>>>>> Subject: [PATCH] f2fs: set specified flag after invalidating nat_bits
>>>>>
>>>>> Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
>>>>> ---
>>>>> fs/f2fs/checkpoint.c | 12 +++++++++++-
>>>>> fs/f2fs/f2fs.h | 3 ++-
>>>>> fs/f2fs/node.c | 3 +++
>>>>> include/linux/f2fs_fs.h | 1 +
>>>>> 4 files changed, 17 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>>>>> index 7e17bb3dfcb1..f7fb14e0f5f9 100644
>>>>> --- a/fs/f2fs/checkpoint.c
>>>>> +++ b/fs/f2fs/checkpoint.c
>>>>> @@ -1226,13 +1226,16 @@ static void update_ckpt_flags(struct f2fs_sb_info
>>>>> *sbi, struct cp_control *cpc)
>>>>> unsigned long orphan_num = sbi->im[ORPHAN_INO].ino_num;
>>>>> struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
>>>>> unsigned long flags;
>>>>> + bool disable_natbits = false;
>>>>>
>>>>> spin_lock_irqsave(&sbi->cp_lock, flags);
>>>>>
>>>>> if ((cpc->reason & CP_UMOUNT) &&
>>>>> le32_to_cpu(ckpt->cp_pack_total_block_count) >
>>>>> - sbi->blocks_per_seg - NM_I(sbi)->nat_bits_blocks)
>>>>> + sbi->blocks_per_seg - NM_I(sbi)->nat_bits_blocks) {
>>>>> disable_nat_bits(sbi, false);
>>>>> + disable_natbits = true;
>>>>> + }
>>>>>
>>>>> if (cpc->reason & CP_TRIMMED)
>>>>> __set_ckpt_flags(ckpt, CP_TRIMMED_FLAG);
>>>>> @@ -1270,11 +1273,18 @@ static void update_ckpt_flags(struct f2fs_sb_info
>>>>> *sbi, struct cp_control *cpc)
>>>>> if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR))
>>>>> __set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG);
>>>>>
>>>>> + if (is_sbi_flag_set(sbi, SBI_NATBIT_NEED_REPAIR))
>>>>> + __set_ckpt_flags(ckpt, CP_NATBIT_NEED_FSCK_FLAG);
>>>>> +
>>>>> /* set this flag to activate crc|cp_ver for recovery */
>>>>> __set_ckpt_flags(ckpt, CP_CRC_RECOVERY_FLAG);
>>>>> __clear_ckpt_flags(ckpt, CP_NOCRC_RECOVERY_FLAG);
>>>>>
>>>>> spin_unlock_irqrestore(&sbi->cp_lock, flags);
>>>>> +
>>>>> + if (disable_natbits)
>>>>> + f2fs_msg(sbi->sb, KERN_NOTICE,
>>>>> + "No enough space in CP area, disable nat_bits.");
>>>>> }
>>>>>
>>>>> static void commit_checkpoint(struct f2fs_sb_info *sbi,
>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>>> index f0cedbe0c536..b55341c269b2 100644
>>>>> --- a/fs/f2fs/f2fs.h
>>>>> +++ b/fs/f2fs/f2fs.h
>>>>> @@ -1107,6 +1107,7 @@ enum {
>>>>> SBI_QUOTA_NEED_FLUSH, /* need to flush quota info in CP */
>>>>> SBI_QUOTA_SKIP_FLUSH, /* skip flushing quota in current CP */
>>>>> SBI_QUOTA_NEED_REPAIR, /* quota file may be corrupted */
>>>>> + SBI_NATBIT_NEED_REPAIR, /* nat full/empty bitmaps need repair */
>>>>> };
>>>>>
>>>>> enum {
>>>>> @@ -1628,7 +1629,7 @@ static inline void disable_nat_bits(struct
>>>>> f2fs_sb_info *sbi, bool lock)
>>>>> {
>>>>> unsigned long flags;
>>>>>
>>>>> - set_sbi_flag(sbi, SBI_NEED_FSCK);
>>>>> + set_sbi_flag(sbi, SBI_NATBIT_NEED_REPAIR);
>>>>>
>>>>> if (lock)
>>>>> spin_lock_irqsave(&sbi->cp_lock, flags);
>>>>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>>>>> index e57add1e8966..0c6f8312a087 100644
>>>>> --- a/fs/f2fs/node.c
>>>>> +++ b/fs/f2fs/node.c
>>>>> @@ -2902,6 +2902,9 @@ static int __get_nat_bitmaps(struct f2fs_sb_info *sbi)
>>>>>
>>>>> cp_ver |= (cur_cp_crc(ckpt) << 32);
>>>>> if (cpu_to_le64(cp_ver) != *(__le64 *)nm_i->nat_bits) {
>>>>> + f2fs_msg(sbi->sb, KERN_NOTICE,
>>>>> + "Disable nat_bits due to incorrect cp_ver (%llu, %llu)",
>>>>> + cp_ver, le64_to_cpu(*(__le64 *)nm_i->nat_bits));
>>>>> disable_nat_bits(sbi, true);
>>>>> return 0;
>>>>> }
>>>>> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
>>>>> index 7196653833fa..1f3ae1504573 100644
>>>>> --- a/include/linux/f2fs_fs.h
>>>>> +++ b/include/linux/f2fs_fs.h
>>>>> @@ -117,6 +117,7 @@ struct f2fs_super_block {
>>>>> /*
>>>>> * For checkpoint
>>>>> */
>>>>> +#define CP_NATBIT_NEED_FSCK_FLAG 0X00002000
>>>>> #define CP_DISABLED_FLAG 0x00001000
>>>>> #define CP_QUOTA_NEED_FSCK_FLAG 0x00000800
>>>>> #define CP_LARGE_NAT_BITMAP_FLAG 0x00000400
>>>>> --
>>>>> 2.18.0.rc1
>>>>>
>>>>>
>>>>>
>>>>>>
>>>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
>>>>>> ---
>>>>>> fs/f2fs/f2fs.h | 6 +++++-
>>>>>> 1 file changed, 5 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>>>> index c28a9d1cb278..aa500239baf2 100644
>>>>>> --- a/fs/f2fs/f2fs.h
>>>>>> +++ b/fs/f2fs/f2fs.h
>>>>>> @@ -1621,7 +1621,11 @@ static inline void disable_nat_bits(struct f2fs_sb_info *sbi, bool lock)
>>>>>> {
>>>>>> unsigned long flags;
>>>>>>
>>>>>> - set_sbi_flag(sbi, SBI_NEED_FSCK);
>>>>>> + /*
>>>>>> + * In order to re-enable nat_bits we need to call fsck.f2fs by
>>>>>> + * set_sbi_flag(sbi, SBI_NEED_FSCK). But it may give huge cost,
>>>>>> + * so let's rely on regular fsck or unclean shutdown.
>>>>>> + */
>>>>>>
>>>>>> if (lock)
>>>>>> spin_lock_irqsave(&sbi->cp_lock, flags);
>>>>>>
>>>>
>>>> .
>>>>
>>
>>
>> _______________________________________________
>> Linux-f2fs-devel mailing list
>> Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
>>
>> .
>>
>
>
> .
>

Next message: Dave Airlie: "[git pull] drm fixes for 4.20-rc5"
Previous message: Ryan Lee: "RE: [PATCH V2] ASoC: max98373: Added max98373_reset for stable amp reset"
In reply to: Sheng Yong: "Re: [f2fs-dev] [PATCH] f2fs: avoid frequent costly fsck triggers"
Next in thread: Jaegeuk Kim: "Re: [f2fs-dev] [PATCH] f2fs: avoid frequent costly fsck triggers"
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