On 2019/12/10 上午2:56, 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:
Thank you a lot for the debug 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
This proves the on-disk numbers are all correct, so far so good.
The remaining problem is the block_rsv part. Which matches with the new
ticket system introduced in v5.4.
Mind to test the new debug snippet?
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index f452a94abdc3..516969534095 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2076,6 +2076,8 @@ static int btrfs_statfs(struct dentry *dentry,
struct kstatfs *buf)
/* Account global block reserve as used, it's in logical size
already */
spin_lock(&block_rsv->lock);
/* Mixed block groups accounting is not byte-accurate, avoid
overflow */
+ pr_info("%s: block_rsv->size=%llu block_rsv->reserved=%llu\n",
__func__,
+ block_rsv->size, block_rsv->reserved);
if (buf->f_bfree >= block_rsv->size >> bits)
buf->f_bfree -= block_rsv->size >> bits;
else
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