Re: [PATCH RFC] Btrfs: fix confusing edquot happening case

[Arne Jansen <sensille@gmx.net>]

On 15.04.2013 13:43, Wang Shilong wrote:
> Hello Arne,
> 
>> On 15.04.2013 12:37, Wang Shilong wrote:
>>> Step to reproduce:
>>> 	mkfs.btrfs <disk>
>>> 	mount <disk> <mnt>
>>> 	dd if=/dev/zero of=/<mnt>/data bs=1M count=10
>>> 	sync
>>> 	btrfs quota enable <mnt>
>>> 	btrfs qgroup create 0/5 <mnt>
>>> 	btrfs qgroup limit 5M 0/5 <mnt>
>>> 	rm -f /<mnt>/data
>>> 	sync
>>> 	btrfs qgroup show <mnt>
>>> 	dd if=/dev/zero of=data bs=1M count=1
>>>
>>> From the perspective of users, qgroup's referenced or referenced
>>>
>>> is negative,But user can not continue to write data! a workaround
>>> way is to cast u64 to int64 when doing qgroup reservation.
>>>
>>> Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
>>> ---
>>> This confusing edquot may also happen after Jan's qgroup
>>> rescan has been implemented.
>>> ---
>>> fs/btrfs/qgroup.c |    4 ++--
>>> 1 files changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
>>> index b44124d..0178223 100644
>>> --- a/fs/btrfs/qgroup.c
>>> +++ b/fs/btrfs/qgroup.c
>>> @@ -1523,14 +1523,14 @@ int btrfs_qgroup_reserve(struct btrfs_root *root, u64 num_bytes)
>>> 		qg = (struct btrfs_qgroup *)(uintptr_t)unode->aux;
>>>
>>> 		if ((qg->lim_flags & BTRFS_QGROUP_LIMIT_MAX_RFER) &&
>>> -		    qg->reserved + qg->rfer + num_bytes >
>>> +		    qg->reserved + (signed long long)qg->rfer + num_bytes >
>>
>> why not use s64 instead of signed long long? Otherwise this is the right way to
>> solve this.
> 
> Yeah,V2 is coming. By the way, do you mind that i add Acked-by: Arne Jasen <sensille@gmx.net>?

You can add a Reviewed-by: Arne Jansen <sensille@gmx.net>

Thanks,
Arne

> 
> Thanks,
> Wang
>>
>> Thanks,
>> Arne
>>
>>> 		    qg->max_rfer) {
>>> 			ret = -EDQUOT;
>>> 			goto out;
>>> 		}
>>>
>>> 		if ((qg->lim_flags & BTRFS_QGROUP_LIMIT_MAX_EXCL) &&
>>> -		    qg->reserved + qg->excl + num_bytes >
>>> +		    qg->reserved + (signed long long)qg->excl + num_bytes >
>>> 		    qg->max_excl) {
>>> 			ret = -EDQUOT;
>>> 			goto out;
>>
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