linux-kernel - Re: XFS status update for January 2011

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Date:	Mon, 14 Feb 2011 08:20:18 -0700
From:	tm@....ma
To:	"Dave Chinner" <david@...morbit.com>
Cc:	"Tao Ma" <tm@....ma>, "Christoph Hellwig" <hch@...radead.org>,
	xfs@....sgi.com, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: XFS status update for January 2011

Hi Dave,
> On Mon, Feb 14, 2011 at 10:17:26AM +0800, Tao Ma wrote:
>> Hi Christoph,
>> On 02/14/2011 02:42 AM, Christoph Hellwig wrote:
>> >On the 4th of January we saw the release of Linux 2.6.37, which
>> contains a
>> >large XFS update:
>> >
>> >     67 files changed, 1424 insertions(+), 1524 deletions(-)
>> >
>> >User visible changes are the new XFS_IOC_ZERO_RANGE ioctl which allows
>> >to convert already allocated space into unwritten extents that return
>> >zeros on a read,
>> would you mind describing some scenario that this ioctl can be used. I
>> am
>> just wondering whether ocfs2 can implement it as well.
>
> Zeroing a file without doing IO or having to punch out the blocks
> already allocated to the file.
>
> In this case, we had a couple of different people in cloud storage
> land asking for such functionality to optimise record deletion
> be avoiding disruption of their preallocated file layouts as a
> punch-then-preallocate operation does.
Thanks for the info. yeah, ocfs2 is also used to host images in some cloud
computing environment. So It looks helpful for us too.
>
> If you you have some kind of use for it in ocfs2, then implementing
> the XFS ioctl is not the correct thing to do - using the fallocate
> patch I've had sitting around (since about 15min after creating the
> XFS ioctl) is most likely the right way to proceed....
yeah, Josef has added the punching hole in fallocate, so I guess another
parameter for keeping the blocks during hole punching should be enough for
us. :)

Regards,
Tao

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