> Hi,
>
>
david@lang.hm writes:
>
>> On Thu, 14 Aug 2008, Arjan van de Ven wrote:
>>
>>> On Thu, 14 Aug 2008 22:04:00 -0400
>>> Theodore Tso <tytso@mit.edu> wrote:
>>>
>>>> On Thu, Aug 14, 2008 at 06:44:33PM -0700,
david@lang.hm wrote:
>>>>> could you do something like defining a namespace inside posix
>>>>> attributes and then setting up a mechanism in the kernel to alert
>>>>> if the attributes change (with the entire namespace getting cleared
>>>>> if the file gets dirtied)?
>>>>
>>>> According to Eric Paris the clean/dirty state is only stored in
>>>> memory. We could use the extended attribute interface as a way of not
>>>> defining a new system call, or some other interface, but I'm not sure
>>>> it's such a great match given that the extended attributes interface
>>>> are designed for persistent data.
>>>>
>>>> I agree that doesn't actually work very well for the tracker use case,
>>>> where you the clean/dirty bit to be persistent (in case the tracker is
>>>> disabled due to the fact you are running on battery, for example, and
>>>> then you reboot).
>>>>
>>>
>>> but we need a "give me all dirty files" solution, not a "is this file
>>> dirty" solution.
>>>
>>> I do not want a virus scanner to constantly have to poll the whole fs
>>> for dirty files ;-)
>>
>> I'm not sure.
>>
>> there are two situations (with the transition between them)
>>
>> 1. unscanned system, we want to do everything. (this happens
>> immediatly after a new signature file is deployed)
>>
>> here you do just want to filter out the files that have been scanned
>> from the list of everything, and you probably want to check at the
>> time of scanning the file in case it was opened (and scanned) in the
>> meantime.
>>
>> 2. mostly scanned system, we only want to scan files that have been
>> dirtied.
>>
>> here you don't need to scan everything, you only need to scan in two cases
>>
>> 2a. the file was dirtied (you learn about it and add it to the queue
>> of files to scan when you get around to it)
>>
>> 2b. an unscanned file is opened (the library detects that the file was
>> not marked approved by all the current scanners, so it invokes the
>> scanners on this file before completing the open, or copy for mmap, or
>> whatever)
>
> 2b could also be used as a general lazy scanning mechanism, no? If
> there is a new signature or the file is dirty or unknown, scan it.
> Always.
>
> So this should all just be one case, no?
