On 09.12.2019 19:56 Martin Raiber wrote:
> On 07.12.2019 08:28 Qu Wenruo wrote:
>> On 2019/12/7 上午5:26, Martin Raiber wrote:
>>> Hi,
>>>
>>> with kernel 5.4.1 I have the problem that df shows 100% space used. I
>>> can still write to the btrfs volume, but my software looks at the
>>> available space and starts deleting stuff if statfs() says there is a
>>> low amount of available space.
>> If the bug still happens, mind to try the snippet to see why this happened?
>>
>> You will need to:
>> - Apply the patch to your kernel code
>> - Recompile the kernel or btrfs module
>> So this needs some experience in kernel compile.
>> - Reboot to newly compiled kernel or load the debug btrfs module
>>
>> Thanks,
>> Qu
>>
>> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
>> index 23aa630f04c9..cf34c05b16d7 100644
>> --- a/fs/btrfs/relocation.c
>> +++ b/fs/btrfs/relocation.c
>> @@ -523,7 +523,8 @@ static int should_ignore_root(struct btrfs_root *root)
>> {
>> struct btrfs_root *reloc_root;
>>
>> - if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
>> + if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
>> + test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state))
>> return 0;
>>
>> reloc_root = root->reloc_root;
>> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
>> index f452a94abdc3..c2b70d97a63b 100644
>> --- a/fs/btrfs/super.c
>> +++ b/fs/btrfs/super.c
>> @@ -2064,6 +2064,8 @@ static int btrfs_statfs(struct dentry *dentry,
>> struct kstatfs *buf)
>> found->disk_used;
>> }
>>
>> + pr_info("%s: found type=0x%llx disk_used=%llu factor=%d\n",
>> + __func__, found->flags, found->disk_used, factor);
>> total_used += found->disk_used;
>> }
>>
>> @@ -2071,6 +2073,8 @@ static int btrfs_statfs(struct dentry *dentry,
>> struct kstatfs *buf)
>>
>> buf->f_blocks = div_u64(btrfs_super_total_bytes(disk_super),
>> factor);
>> buf->f_blocks >>= bits;
>> + pr_info("%s: super_total_bytes=%llu total_used=%llu
>> factor=%d\n", __func__,
>> + btrfs_super_total_bytes(disk_super), total_used, factor);
>> buf->f_bfree = buf->f_blocks - (div_u64(total_used, factor) >>
>> bits);
>>
>> /* Account global block reserve as used, it's in logical size
>> already */
>>
> Applied. It's currently 100% used directly after reboot, and I am
> getting this log output:
>
> [...]
> [ 241.245150] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 241.904824] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 241.904824] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 241.904824] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 241.904824] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 241.976082] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 241.976082] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 241.976082] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 241.976082] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 241.976083] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 241.976083] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 241.976083] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 241.976083] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 242.245301] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 242.245301] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 242.245301] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 242.245301] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 242.904977] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 242.904977] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 242.904977] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 242.904977] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 242.976105] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 242.976105] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 242.976105] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 242.976105] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 242.977777] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 242.977777] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 242.977777] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 242.977777] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 243.245041] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 243.245041] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 243.245041] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 243.245041] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 243.252079] btrfs_statfs: found type=0x1 disk_used=30026579968 factor=1
> [ 243.252079] btrfs_statfs: found type=0x4 disk_used=957202432 factor=1
> [ 243.252079] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 243.252079] btrfs_statfs: super_total_bytes=49999998976
> total_used=30983798784 factor=1
> [ 243.252080] btrfs_statfs: found type=0x1 disk_used=30026579968 factor=1
> [ 243.252080] btrfs_statfs: found type=0x4 disk_used=957202432 factor=1
> [ 243.252080] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 243.252080] btrfs_statfs: super_total_bytes=49999998976
> total_used=30983798784 factor=1
> [ 243.904085] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 243.904086] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 243.904086] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 243.904086] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 243.976096] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 243.976096] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 243.976096] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 243.976096] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 243.976257] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 243.976257] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 243.976257] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 243.976258] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 244.081959] btrfs_statfs: found type=0x1 disk_used=665652932608 factor=1
> [ 244.081959] btrfs_statfs: found type=0x4 disk_used=4902944768 factor=1
> [ 244.081959] btrfs_statfs: found type=0x2 disk_used=98304 factor=1
> [ 244.081959] btrfs_statfs: super_total_bytes=8133881348096
> total_used=670555975680 factor=1
> [ 244.084110] btrfs_statfs: found type=0x1 disk_used=665652932608 factor=1
> [ 244.084110] btrfs_statfs: found type=0x4 disk_used=4902944768 factor=1
> [ 244.084110] btrfs_statfs: found type=0x2 disk_used=98304 factor=1
> [ 244.084110] btrfs_statfs: super_total_bytes=8133881348096
> total_used=670555975680 factor=1
> [ 244.245470] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 244.245470] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 244.245470] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 244.245470] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 244.904170] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 244.904170] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 244.904170] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 244.904170] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 244.977624] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 244.977624] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 244.977624] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 244.977624] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 244.977387] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 244.977387] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 244.977387] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 244.977387] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
> [ 245.244089] btrfs_statfs: found type=0x1 disk_used=93464006656 factor=1
> [ 245.244089] btrfs_statfs: found type=0x4 disk_used=314818560 factor=1
> [ 245.244089] btrfs_statfs: found type=0x2 disk_used=16384 factor=1
> [ 245.244089] btrfs_statfs: super_total_bytes=128835387392
> total_used=93778841600 factor=1
It went back to 9% afterwards (without reboot, sync() perhaps?). I hope
it didn't go back while the above was logged. I'll keep an eye on it.
>>> # df -h
>>> Filesystem Size Used Avail
>>> Use% Mounted on
>>> ...
>>> /dev/loop0 7.4T 623G 0
>>> 100% /media/backup
>>> ...
>>>
>>> statfs("/media/backup", {f_type=BTRFS_SUPER_MAGIC, f_bsize=4096,
>>> f_blocks=1985810876, f_bfree=1822074245, f_bavail=0, f_files=0,
>>> f_ffree=0, f_fsid={val=[3667078581, 2813298474]}, f_namelen=255,
>>> f_frsize=4096, f_flags=ST_VALID|ST_NOATIME}) = 0
>>>
>>> # btrfs fi usage /media/backup
>>> Overall:
>>> Device size: 7.40TiB
>>> Device allocated: 671.02GiB
>>> Device unallocated: 6.74TiB
>>> Device missing: 0.00B
>>> Used: 622.49GiB
>>> Free (estimated): 6.79TiB (min: 6.79TiB)
>>> Data ratio: 1.00
>>> Metadata ratio: 1.00
>>> Global reserve: 512.00MiB (used: 0.00B)
>>>
>>> Data,single: Size:666.01GiB, Used:617.95GiB
>>> /dev/loop0 666.01GiB
>>>
>>> Metadata,single: Size:5.01GiB, Used:4.54GiB
>>> /dev/loop0 5.01GiB
>>>
>>> System,single: Size:4.00MiB, Used:96.00KiB
>>> /dev/loop0 4.00MiB
>>>
>>> Unallocated:
>>> /dev/loop0 6.74TiB
>>>
>>> # btrfs fi df /media/backup
>>> Data, single: total=666.01GiB, used=617.95GiB
>>> System, single: total=4.00MiB, used=96.00KiB
>>> Metadata, single: total=5.01GiB, used=4.54GiB
>>> GlobalReserve, single: total=512.00MiB, used=0.00B
>>>
>>> # mount
>>>
>>> ...
>>> /dev/loop0 on /media/backup type btrfs
>>> (rw,noatime,nossd,discard,space_cache=v2,enospc_debug,skip_balance,commit=86400,subvolid=5,subvol=/)
>>> ...
>>>
>>> (I remounted with enospc_debug and the available space did not change...)
>>>
>>> Regards,
>>> Martin Raiber
>>>
