how to create file without using extent allocation

[Akshay Nehe]

On 3/22/12, Greg Freemyer <greg.freemyer at gmail.com> wrote:
>> On 3/22/12, Vlad Dogaru <ddvlad at rosedu.org> wrote:
>>> On Thu, Mar 22, 2012 at 3:31 PM, Akshay Nehe <akshaynehe785 at gmail.com>
>>> wrote:
>>>> Hello,
>>>>
>>>> Can we create file on ext4 file system which dose not uses extent
>>>> allocation?
>>>
>>> Man page of mkfs.ext4 suggests using "-O ^feature" to disable an ext4
>>> feature.  This seems to work:
>>>
>>> $ dd if=/dev/zero of=test1 bs=4M count=20
>>> [...]
>>> $ mkfs.ext4 -F test1
>>> [...]
>>> $ file test1
>>> test1: Linux rev 1.0 ext4 filesystem data,
>>> UUID=408f6da2-c4ef-4335-9574-985f3a349ed2 (extents) (huge files)
>>>
>>> $ mkfs -O ^extent -F test1
>>> [...]
>>> $ file test1
>>> test1: Linux rev 1.0 ext4 filesystem data,
>>> UUID=23c046d6-db7a-419d-a1d5-0cba3c5b52d0 (huge files)
>>>
>>> Hope this helps,
>>> Vlad
>>>
>
>
> On Thu, Mar 22, 2012 at 9:59 AM, Akshay Nehe <akshaynehe785 at gmail.com>
> wrote:
>> Thanks for help, i find it useful.
>>
>> --
>> Regards,
>> Akshay Nehe.
>
> Akshay,
>
> 1) If you are going to participate in kernel mailinglists, you need to
> be aware the appropriate netiquette is to bottom post all responses.
> I have moved your reply to the bottom to make this flow better.
>
    Okay I got it, I will follow right method from now onwards.

> 2) I assume you see it is a mkfs option that controls this.  So you
> can't control it on a file by file basis as far as I know.  I don't
> think you can even control it by re-mounting.  Instead you have to
> reformat, so it is a fundamental change.
>
    Actually I want to create files which uses indirect block mapping
on ext4 file-system. I have mounted loop device with ext4 file-system,
can I create files on it using indirect block mapping?
> Greg
>


-- 
Regards,
Akshay Nehe.