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
>
>> # 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
>>
