Re: ext2/3/4: punch support?
From: Eric Sandeen
Date: Mon Feb 28 2011 - 10:18:05 EST
On 2/28/11 8:29 AM, Dave Young wrote:
> On Mon, Feb 28, 2011 at 9:11 PM, Josef Bacik <josef@xxxxxxxxxx> wrote:
>> On Mon, Feb 28, 2011 at 03:03:40PM +0800, Dave Young wrote:
>>> Hi, josef and ext guys
>>> Do you have any plan with ext4 hole punching support? And the
>>> fallocate for ext2/3?
>>> What's the obstacle to work on this? could someone tell the status of
>>> this issue?
>> There is no obstacle, just nobody has bothered to do it. If you want to do it
>> go for it. Thanks,
> Yes, I want to do some kvm image space discard stuff,
> I use ext4 as my filesystem, but currently only xfs support something
> like trim/discard.
As Lukas said, ext4 & ext3 support various forms of trim/discard already.
But that's different from punch...
And as for fallocate on ext3, you need somewhere to put the metadata to indicate a block is allocated but not written. This was a lot more straightforward for ext4, since it describes a large range of blocks with a single extent structure.
> I know general knowledge about ext filesystem, but nearly new to ext4 code,
> could you give some hint where to start?
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/