[pacman-dev] Diskspace checking thought- free space cushion

[Allan McRae]

On 15/12/10 11:54, Dan McGee wrote:
> On Tue, Dec 14, 2010 at 7:51 PM, Allan McRae<allan at archlinux.org>  wrote:
>> On 15/12/10 10:01, Dan McGee wrote:
>>>
>>> Code in question is diskspace.c, line ~300:
>>>
>>>    for(i = mount_points; i; i = alpm_list_next(i)) {
>>>      alpm_mountpoint_t *data = i->data;
>>>      if(data->used == 1) {
>>>        _alpm_log(PM_LOG_DEBUG, "partition %s, needed %ld, free %ld\n",
>>>            data->mount_dir, data->max_blocks_needed,
>>>            (unsigned long)data->fsp.f_bfree);
>>>        if(data->max_blocks_needed>    data->fsp.f_bfree) {
>>>          abort = 1;
>>>        }
>>>      }
>>>    }
>>>
>>> This does a strict check of max_blocks_needed>    fsp.f_bfree. do we
>>> want to cushion this somehow, as having 1 block free could still spell
>>> disaster given logging, post-install scripts, etc.? And if so, how
>>> much? I don't want to make this something that has loads and loads of
>>> configuration- we hardcode max delta ratio at 0.7, for instance. Is 5%
>>> of total blocks, capped at something like 10 MB (in 4K blocks that
>>> would be 2560 blocks) enough?
>>>
>>
>> I thought about that, especially given there is some handwaving about blocks
>> taken for directories, database entries etc.  I did not using a percentage
>> or a fixed size, but the combination might be good. max(5%,10M) sounds fine
>> although maybe a bit more than 10MB would be good.
>
> max, or min? 5% will be huge on big drives. I meant min without
> actually saying it.

Yes...   I meant min while saying max.

Allan