Re: files of size larger than fs size

[Max <relf@unn.ac.ru>]

Thanks for the explanation.
I closed my bugreport as INVALID.

But anyway it's ineteresting why the resulting sparse files have different size on different fs?

Max

Phillip Lougher wrote:
> Max wrote:
> 
>> Hello!
>>
>> I've discovered that it is possible to create files of size much 
>> larger than partition size.
>> I thought that this is JFS bug, so I've filed a bugreport against it 
>> at http://bugzilla.kernel.org/show_bug.cgi?id=4345
>> Detailed info and testcase program are provided there.
>>
>> Later I've found that at least XFS and EXT3 filesystems have the same 
>> problem (though the resulting filesize is different for each fs). So 
>> the problem may be not in fs code but in some other piece of kernel.
>>
>> Could kernel gurus please investigate the problem?
>>
> 
> Your test case isn't writing a full file, it is only writing 4 bytes at 
> various offsets (1^32, 1^40, 1^48, 1^56).
> 
> The filesystems you mention support files with "holes" in them, in 
> otherwords they support gaps between data which don't take up any storage.
> 
> Even though your test case is creating a huge file, only a couple of 
> bytes are written, the rest of the huge file doesn't take up any space.
> 
> The behaviour you're seeing isn't a bug...
> 
> Phillip Lougher
> 
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
>