XFS support for TRIM / blkdev_issue_discard?

[Eric Sandeen]

Dave Chinner wrote:
> On Tue, Apr 14, 2009 at 01:32:35PM -0500, Felix Blyakher wrote:
>> On Apr 14, 2009, at 9:44 AM, Peter Niemayer wrote:
>>
>>> Dear Felix Blyakher,
>> Hi Peter,
>>
>>> do you know whether there are plans to support the ATA TRIM command /
>>> blkdev_issue_discard() call in XFS for Linux anytime soon?
>> This topic was indeed brought up in xfs discussions.
>> Though, we don't have any definite plans on supporting it yet.
> 
> I did some initial work on tracking extents being freed, but then
> the TRIM request morphed into a "tell the largest free space around
> the area just freed" and that is much harder to do than simply to
> issue a "we just freed this bit" command.

FWIW, ext[34] is still doing it block by block.  At least for SSDs, I
think that's fine, isn't it?  For think provisioning it might be
different.  I  think (?) the simply block-by-block free is still
relevant, no?

-Eric